Patent Application
20110002568
This application is based on and claims Convention priority to Japanese patent applications No. 2008-72930, filed Mar. 21, 2008; No. 2008-74964, filed Mar. 24, 2008; No. 2008-181163, filed Jul. 11, 2008; No. 2008-181164, filed Jul. 11, 2008; No. 2008-212744, filed Aug. 21, 2008; No. 2008-212745, filed Aug. 21, 2008; No. 2008-212746, filed Aug. 21, 2008; and No. 2009-37447, filed Feb. 20, 2009, the entire disclosures of which are herein incorporated by reference as a part of this application.
The present invention relates to a snap cage in and for a ball bearing assembly and a ball bearing assembly having such cage assembled therein.
A sealed ball bearing assembly that is used in various rotary apparatuses and equipments, particularly automobile auxiliary equipments is generally required to have a resistance to high temperature, a resistance to high speed, a resistance to muddy water, a dust controllability, a resistance to grease leakage, a long servicing life and a low torque characteristic and, particularly in order to meet with the resistance to muddy water and the dust controllability, contact sealing members are employed at opposite ends of a bearing space delimited between inner and outer rings of the bearing assembly.
In the sealed ball bearing assembly of the structure described above, if the bearing temperature increases while grease is present in a sealing lip segment of any of those sealing members, the pressure inside the bearing assembly increases as a result of expansion of air inside the bearing assembly, thus bringing about a difference in pressure between inside and outside of the bearing assembly to such an extent as to result in opening of the sealing lip segment. Once the sealing lip segment opens by the effect of the pressure difference, the phenomenon occurs, in which the grease and air both present inside the bearing assembly leak (hereinafter referred to as “breath”) to the outside of the bearing assembly. (See the Patent Document 1 listed below.)
To avoid the breathing phenomenon discussed above, suggestion has been made, in which a ventilating cutout is defined in a portion of the sealing lip segment referred to above. (See the Patent Document 1 listed below.) It has, however, been found that if the grease deposits on the cutout so employed, grease leakage tends to occur in a manner similar to that occurring in the previously described ball bearing assembly. (See the Patent Document 2 listed below.)
It may be contemplated that in, for example, a ball bearing assembly of an inner ring rotating type in which no cutout referred to above is employed, the pressure of urging the seal lip segment against a seal groove, which is defined in an outer diametric surface of an inner ring (which pressure is hereinafter referred to as “tensing force”), is increased to accomplish the countermeasure against the breathing phenomenon. It has, however, been found that this countermeasure tends to merely brings about an increase of the bearing torque and is incapable of avoiding the grease leakage particularly in the event of a large temperature rise enough to result in the internal pressure of a value higher than the tensing force. Also, in the event of a decrease of the bearing temperature, the internal pressure decreases as a result of shrinkage of the air inside the bearing assembly and, therefore, an attachment phenomenon, in which the tip of the sealing lip segment is sucked, will occur, resulting in a further increase of the bearing torque. (See, for example, the Patent Document 3 listed below.)
For this reason, even though any of the various structures as the contact sealing member is employed, the grease leakage will be hardly avoided once the grease deposits in the inner ring seal groove.
In view of the foregoing, the cage for ball bearing assemblies has been suggested, in which the shape of a steel ribbon cage is altered to avoid the grease leakage. (This type of cage is hereinafter referred to as an “improved steel ribbon cage”.) (See the Patent Document 4 listed below.) In this cage, the radius of a circumferential portion of the inner diameter, where pockets for accommodating respective bearing balls are defined, as measured from the center of the cage, is made greater than the radius of a circumferential portion of the inner diameter, which lies between the neighboring pockets, as measured from the center of the cage. With this structure an excessive grease, depositing on balls at that circumferential portion having a large inner diameter, can be scraped off from the balls to thereby prevent the grease from depositing on an inner ring shoulder.
It has, however, been found that if the structure employed in the improved steel ribbon cage for avoiding the grease leakage is adopted in the standard snap cage, an intermediate portion of the cage between the neighboring pockets, at which the minimum sectional surface area is attained in the snap cage, will further be reduced, and therefore, application of such structure to the snap cage is difficult to achieve.
Another attempt has also been made, in which each of bridge portions of the resinous snap cage positioned between the neighboring pockets has its rear surface (a surface opposite to the direction in which each of the pockets is open) is opened as a countermeasure for the grease leakage. (See the Patent Document 5 listed below.) Thus, in this cage, the volume of each of the bridge portions between the neighboring pockets is reduced to increase the space capacity in the bearing space to thereby improve the grease leakproof. The resinous snap cage employed in this case has a shape similar to the grease leak-proofing structure employed in the improved steel ribbon cage referred to previously.
However, in order to adopt such a grease leak-proofing structure of a kind described above in the snap cage utilizing a resin generally considered to have a strength lower than that of iron, the axial length thereof need be increased, but increase of the axial length results in increase of the surface area of an inner diametric surface as compared with that in the steel ribbon cage. Once the surface area of the inner diametric surface increases, the grease is correspondingly apt to deposit, leading to an undesirable possibility of grease leakage. Accordingly, a large effect of suppressing the grease leakage can be hardly anticipated.
In view of the recent orientation towards the high performance of the automobile auxiliary machines and equipments, the various rotary component parts are desired to have a high speed feature. Particularly where in designing such a high speed feature, the crown shaped resinous cage is utilized, the strength of the cage is controversial. Accordingly, a method of enhancing the strength of the crown shaped resinous cage against a delay and an advance of rolling elements has been suggested, in which a groove for separating an inner diametric side wall portion and an outer diametric side wall portion from each other is provided in an axial end face of the cage in a direction circumferentially thereof. (See the Patent Document 6 listed below.) In this example, since the cage has the inner diametric side wall portion and the outer diametric side wall portion separated from each other by the groove, the inner diametric side wall portion tends to resiliently tilted radially inwardly and the outer diametric side wall portion tends to resiliently tilt radially outwardly, in correspondence with the delay and the advance of rolling elements, to accommodate the delay-advance of the rolling elements. By so doing, the stress imposed on the cage is dispersed.
Also, in order to increase the strength of the resinous cage, incorporation of a reinforcement member into the cage has been suggested. (See the Patent Document 7 listed below.)
As discussed above, as the countermeasure for the grease leakage in the sealed ball bearing assembly, the tensing force of the sealing lip segment, the shape of the sealing lip segment and the cutout have been tailored as disclosed in the Patent Documents 1 to 3 referred to previously, but those countermeasures pose such a problem that if grease exists in the seal groove and/or an inner ring outer diametric portion as a result of rotation, the temperature inside the bearing assembly increases, accompanied by the occurrence of a grease leakage.
Also, although the improved steel ribbon cage disclosed in the Patent Document 4 referred to above is effective in avoiding the grease leakage, application of this grease leak-proofing structure to the snap cage is limited in terms of strength and, therefore, such application is difficult to achieve. In addition, since the resinous material often used in the snap cage has a strength lower than that of iron, application of that grease leak-proofing structure to the snap cage requires the axial thickness of the snap cage to be increased and as mentioned above, this has been found involving an increase of the amount of grease deposited on the cage inner diametric surface, hence making it difficult to avoid the grease leakage.
In the resinous snap cage disclosed in the Patent Document 6 referred to above, the cage tends to be further tilted towards an outer diametric side by the effect of a centrifugal force when it is rotated at high speed, and therefore, there is the possibility that the cage outer diametric side may undesirably contact the outer ring inner diametric side.
By way of example, in the cage in which the reinforcement member is incorporated as disclosed in the Patent Document 7 referred to above, an injection molding or the like must be carried out by supplying a resinous material into a mold assembly while a metal element has been set inside the mold assembly. Accordingly, this results in increase of the number of manufacturing process steps, accompanied by increase of the cost and the weight.
No cage having a resistance to grease leakage and capable of being rotated at high speed have yet been made available.
An object of the present invention is to provide a snap cage in a ball bearing assembly, in which the amount of grease tending to deposit inside the cage inner diametric portion is reduced to thereby avoid an undesirable leakage of the grease and also to provide such ball bearing assembly having such cage assembled therein.
Another important object of the present invention is to provide the snap cage in the ball bearing assembly, which has a resistance to grease leakage and is capable of withstanding a high speed rotation as compared with the conventional cage, and also to provide such ball bearing assembly.
In order to accomplish those objects, the present invention provides a snap cage in and for a ball bearing assembly, which includes an annular body having one side face opened at a plurality of circumferential locations to define respective pockets each retaining a ball and having an inner face, a recessed area defined in the inner face of the respective pocket so as to extend from a pocket open edge on a cage inner diametric side towards a cage outer diametric side.
According to the cage of the structure described above, since the inner side face of each of the pockets is provided with the recessed area so as to extend from the pocket open edge on the cage inner diametric side towards the cage outer diametric side, the amount of grease sticking to each of the balls and scraped by an inner diametric surface of the cage decreases. Accordingly, since the deposition of the grease onto the inner ring outer diametric portion is avoided, flow of the grease towards a seal groove in the inner ring is avoided and, as a result, the leakage of the grease from the ball bearing assembly can be avoided.
In the present invention, an axial position of the recessed area in each of the pockets may be a position substantially coinciding with a shoulder portion of a raceway surface of an inner ring. That is because the grease is carried up by the contact of the balls with the inner ring raceway to the raceway shoulder portion to accumulate on a portion of the cage inner diametric surface which portion lies in the vicinity of the axial position that substantially coincide with the raceway shoulder portion.
In the present invention, the recessed area may be provided at a plurality of locations while positioned on respective sides of a center of the pocket in a cage circumferential direction at the open edge of each of the pockets and the inner face of each of the recessed areas may be of a substantially cylindrical surface shape following a surface of the imaginary cylinder having its center lying in a direction radially of the cage and be of such a shape that each of the recessed areas extends from the open edge on the cage inner diametric side towards a pitch circle of arrangement of a row of the balls and has a width gradually getting shallow and narrow from a cage inner diametric edge to the pitch circle of the row of the balls.
In the present invention, the recessed area may be provided at two locations on respective sides of a center of the pocket in a cage circumferential direction at the open edge of each of the pockets so as to extend to a position proximate to a cage outer diametric edge and the inner face of each of the two recessed areas may be of a shape substantially following a surface of the imaginary ring, the imaginary ring having a sectional shape at any arbitrarily chosen circumferential position representing a round shape, a ring center being inclined relative to a cage center axis.
In the present invention, the recessed area may be provided at one location while spreading from a center of the pocket in a cage circumferential direction at the open edge of the pockets towards respective sides of the cage circumferential direction and has a width greater than half the width of the pocket in the cage circumferential direction; in which the inner face of the recessed area may represent a substantially cylindrical surface shape following a surface of the imaginary cylinder having its center aligned with a straight line extending in a radial direction of the cage, and in which the recessed area may extend from the open edge on the cage inner diametric side towards a location adjacent a pitch circle of a row of the balls and may have a width gradually getting shallow and narrow from a cage inner diametric edge to the pitch circle of the row of the balls.
In the present invention, the inner face of the pocket may represent a concaved spherical surface shape and a bridge portion may be provided between the neighboring pockets. The bridge portion may have an end point on a side opposite to a pocket open side on a cage inner diametric surface in a section at a center position of the cage circumferential direction with an axial position of such end point lying at a position adjacent a center side of a raceway surface and remote from a shoulder of a raceway surface of an inner ring. By so doing, the leakage of the grease from the inner diametric surface of the bridge portion to the bearing outside can be avoided.
In the present invention, the pocket has a pocket bottom wall, and a portion of the pocket bottom wall at a center of the pocket in the cage circumferential direction may be of such a shape that the wall thickness of the pocket bottom wall portion is greater at an inner diametric side than at an outer diametric side. In a ball bearing assembly having a sealing plate fitted thereto, the distance between a cage, employed therein, and the sealing plate is large on the outer diametric side and small on the inner diametric side. In such case, it is difficult to expand the cage as a whole in the axial direction. In view of this, the wall thickness of the pocket bottom wall portion on the outer diametric side is chosen to be greater than the wall thickness on the inner diametric side so that the maximum stress imposed on the cage and the amount of displacement can be reduced without allowing the sealing plate and the cage contacting with each other. Accordingly, the above described object to enable a high speed operation can be accomplished.
In the present invention, a pair of pawls opposed to each other in a circumferential direction are preferably employed, in which case the pair of pawls are to be provided on the open side of the pocket so as to protrude in an axial direction. According to this construction, the ball can be stably retained within the respective pocket by the pawls.
Preferably, the distance between respective tip portions of the pair of the pawls in the pocket on the cage outer diametric side is smaller than the distance between the tip portions of the pair of the pawls in the pocket on the cage inner diametric side. According to this construction, since the distance between respective tip portions of the pair of the pawls in the pocket on the cage outer diametric side is smaller than the distance between the tip portions of the pair of the pawls in the pocket on the cage inner diametric side, the grease adhering to the balls is not permitted to approach from the outer ring side towards the outer diametric portion of the inner ring. On the other hand, the grease from the inner ring side can be scraped by the cage inner diametric side of the pawls distant from the outer diametric portion of the inner ring. Consequently, the leakage of the grease from the ball bearing assembly can be avoided.
Preferably, respective tip portions of the pair of the pawls in the pocket on the cage inner diametric side are opened, but respective tip portions of the pair of the pawls in the pocket on the cage outer diametric side are connected together. According to this construction, since the respective tip portions of the pair of the pawls in the pocket on the cage inner diametric side are opened, but respective tip portions of the pair of the pawls in the pocket on the cage outer diametric side are connected together, the grease adhering to the balls is not permitted to approach from the outer ring side towards the outer diametric portion of the inner ring. On the other hand, the grease from the inner ring side can be scraped by the cage inner diametric side of the pawls distant from the outer diametric portion of the inner ring. Consequently, the leakage of the grease from the ball bearing assembly can be avoided.
Also, in order to increase the grease leakage preventive effect, it is preferred that the pair of pawls are provided on the cage inner and outer diametric sides, respectively, and assuming that the total width of the pawl, when projected onto a straight line extending a cage radial direction across the center of each of the pockets in a cage circumferential direction, is expressed by It, the width Ie of a pawl portion of the pawl on a cage outer diametric side, when projected onto the straight line, is of a value not greater than ⅔ It.
In addition, in order to increase the grease leakage preventive effect, it is also preferred that the angle in a cage circumferential direction from a pocket center equivalent position in the section, taken along the cage circumferential direction, to a pawl tip portion on a cage outer diametric side is chosen to be of a value not smaller than 1.5 times the corresponding angle of the pawl tip portion on a cage inner diametric side.
The ball bearing assembly of the present invention is a ball bearing assembly having incorporated therein the cage designed and constructed in accordance with the present invention.
In a single row ball bearing assembly, the behavior of the grease towards the pocket opened side makes no difference from that exhibited in the ball bearing assembly having the standard snap cage incorporated therein and no grease leakage preventive effect can therefore be expected. However, the ball bearing assembly is often utilized in a pair and, hence, in most cases leakage of the grease towards both end sides of the pair of the ball bearing assemblies are not called for. In such case, if the back face side of the cage of the present invention is incorporated while being oriented towards the side where a countermeasure to avoid the grease leakage is taken, the grease sealing function of the final pair product can be maintained.
In the ball bearing assembly of the present invention, a plurality of balls interposed between inner and outer rings are retained by the cage; a grease composition is filled in a bearing space delimited between the inner and outer rings; and a sealing member provided in the outer ring or the inner ring for closing the bearing space; and in which the grease composition is filled in the bearing space; the grease composition is prepared by blending an additive to a base grease containing a base oil and a thickener; the additive is at least an aluminum series additive selected from the group consisting of an aluminum powder and an aluminum compound; and the aluminum series additive is blended in a quantity within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the base grease.
According to the above described construction, since the snap cage is adopted in the ball bearing assembly and the inner face of each of the pockets in the cage is provided with the recessed area extending from the pocket open edge on the cage inner diametric side towards the cage outer diametric side, the amount of the grease sticking to the balls and scraped by the inner diametric surface of the cage is reduced. Accordingly, the grease leakage from the cage pocket back face side is suppressed and the deposition of the grease on the inner ring outer diametric portion can be avoided. Therefore, the flow of the grease into the seal groove can be avoided and, hence, the grease leakage from the ball bearing assembly can be avoided.
Also, since the grease composition filled in this bearing space is of a composition including the additive mixed in the base grease prepared by mixing the base oil and the thickener, which additive contains at least one aluminum series additive selected from the group consisting of the aluminum powder and the aluminum compound and since the amount of the aluminum series additive added is within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the base grease, the occurrence of the peculiar exfoliation caused by the hydrogen brittleness can be suppressed. Accordingly, the service lifetime of the ball bearing assembly filled with this grease composition can be increased.
Since the grease leakage can be avoided owning to the above described cage, there is no need to change the design and the shape of the seal groove in the inner ring and, also, to axially arrange, for example, a slinger or the like in the bearing assembly. Accordingly, without the number of component parts being increased, space saving can be accomplished.
Since by adopting the cage of the type described above and the grease composition of the kind described above, the bearing assembly can be operated under a feasible condition without the hydrogen brittleness and there is no grease leakage occurring, the lubricating duration characteristic possessed by the grease filled in the bearing space can be sufficiently exhibited. Also, contamination of the external environment resulting from the grease leakage and obnoxious noises generated as a result of corrosion and/or slippage of, for example, an engine auxiliary machine belt or the like can be avoided. Also, as compared with the conventional case, the manufacturing cost reduction can be achieved as a result of reduction in number of component parts.
The aluminum compound may include at least one compound selected from the group consisting of aluminum carbonate and aluminum nitrate.
The ball bearing assembly of the present invention may be a ball bearing assembly dedicated to a rotary encoder equipped motor for supporting a rotary shaft of a rotary encoder equipped motor, which includes a plurality of balls interposed between an inner ring and an outer ring and retained by a cage, and a sealing member fitted to the outer ring or the inner ring for sealing a bearing space.
According to the construction described above, since the inner face of each of the pockets in the snap cage is provided with the recessed area extending from the pocket open edge on the cage inner diametric side towards the cage outer diametric side, the flow of the grease towards a sensor of the rotary encoder or the seal groove in the inner ring can be avoided and, hence, the grease leakage from the ball bearing assembly for the rotary encoder equipped motor can be avoided.
Accordingly, deposition of the grease on the sensor or the like of the rotary encoder is avoided and the rotational condition can be accurately detected. Also, since the grease leakage can be avoided, the non-contact sealing member can be adopted and, hence, a low torque can be achieved. Even when this non-contact sealing member is adopted, the dust proofing property can be increased by the cage of the construction referred to above.
The ball bearing assembly of the present invention may include a plurality of balls interposed between inner and outer rings and retained by the cage and a sealing member provided in the outer ring for closing the bearing space; in which a seal groove is formed in an outer diametric surface of the inner ring in a circumferential direction; the sealing member having an outer peripheral edge fixed to an outer ring inner diametric surface opposed to the seal groove; the sealing member also having an inner peripheral portion provided with primary and auxiliary sealing lips, the primary sealing lip being held in contact with the seal groove to thereby form a contact seal whereas the auxiliary sealing lip being held proximate to the seal groove or its neighborhood to thereby form a labyrinth seal, and in which a branched portion is provided at a position of the sealing member proximate to a level of the inner ring outer diametric surface; the primary sealing lip being formed by a portion protruding from the branched portion in an inner diametric direction and having a tip portion held in contact with an outer side groove wall of the seal groove to thereby form the contact seal; and the auxiliary sealing lip is formed by a portion protruding from the branched portion in the axially inward direction, the labyrinth seal being formed between a tip portion of the auxiliary sealing lip and an inner side groove wall of the seal groove.
According to the construction described above, since the snap cage is provided with the recessed area, the grease leakage from the cage back face side can be suppressed. Accordingly, deposition of the grease onto the inner ring outer diametric portion can be avoided. Also, in the sealing member, the labyrinth seal, formed by the auxiliary sealing lip, and the contact seal formed by the primary sealing lip are sealed to avoid an undesirable leakage to the outside. Intrusion of foreign matters from the outside can also be avoided by the contact seal and the labyrinth seal.
Since the outer diametric surface of the auxiliary sealing lip spreads axially at the height about equal to that of the inner ring outer diametric surface neighboring the seal groove, the grease purged from the raceway groove side smoothly move towards the outer diametric surface of the auxiliary sealing lip. Therefore, the amount of grease passing through the labyrinth seal can be reduced. Since the internal pressure of the bearing assembly is relieved by the auxiliary sealing lip, the internal pressure acting on the primary sealing lip is reduced. Therefore, the tightening allowance of the contact seal formed by the primary sealing lip can be reduced to achieve the low bearing torque. Thus, when the sealing member is used in this way, a low torque and a high sealing characteristic can be realized owing to the labyrinth structure. In such case, the necessity of a space for installation of a slinger or the like is eliminated and the manufacturing cost can be reduced with no number of component parts increased.
The ball bearing assembly of the present invention may also include a plurality of balls interposed between inner and outer raceway rings and retained by the cage and a sealing member provided in the outer ring or the inner raceway ring for closing the bearing space; in which the sealing member has circumferential edges opposite to each other, one of the circumferential edges of the sealing member being slidingly engaged in a seal groove formed in an end of one of the raceway rings and the other of the circumferential edges of the sealing member being fixed to an end of the other of the raceway rings; and in which the peripheral edge of the sealing member slidingly engaged in the seal groove is rendered to be a sealing lip and has an inner side face formed with a projection, the projection being capable of displacing between a first condition, in which when as a result of development of a pressure difference occurring in the inside of the bearing assembly and the outside of the bearing assembly that are divided by the sealing member, the projection contacts the inner side face of the seal groove and, as a result of this contact of the projection, the sealing lip in proximity to the contact is partially elastically deformed to form an air passage that communicate between the inside of the bearing assembly and the outside of the bearing assembly, and a second condition, in which in the absence of the pressure difference referred to above, the projection is held in a non-contact with the inner side face of the seal groove.
According to the construction described above, since the snap cage is provided with the recessed area, the grease leakage from the cage back face side can be suppressed. Accordingly, deposition of the grease onto the inner ring outer diametric portion can be suppressed. Also, in the sealing member, although occurrence of the suction or attachment phenomenon makes the sealing lip urged inwardly, the projection on the inner face of the sealing lip is urged against the seal groove inner side face simultaneously with the sealing lip being so urged. At this time, due to the presence of the projection, the sealing lip at a location in the vicinity of the position of contact of the projection with the seal groove inner side face is elastically partially deformed relative to the other portion. In other words, the sealing lip in the vicinity of the position of contact of the projection is incapable of contacting the inner side face of the seal groove and, due to its non-contact, the air passage is formed for communicating the bearing inside and the bearing outside.
In a condition, in which the projection and the sealing lip tip portions are held in contact with the inner side face of the seal groove, the sliding resistance of the projection tip portion becomes higher than that of the tip portion of the sealing lip, depending on the difference in contact pressure between the projection and the sealing lip tip portion. When the bearing assembly is rotated under this condition, the sealing lip tip portion will be twisted, having been undulated in a wavy fashion, resulting in formation of the air passage. For this reason, the suction phenomenon of the sealing member can be avoided with the balance in pressure between the bearing inside and outside instantly maintained uniformly. The air passage necessary to maintain this pressure balance is immediately closed if the balance in pressure between the bearing inside and outside is maintained, that is, no pressure difference is developed, and the sealing lip assumes a normal condition. At this time, the projection is in non-contact with the inner side face of the seal groove. Accordingly, intrusion of foreign matters from the bearing outside is minimized and, since the air passage therefor is narrow, there is no possibility that the grease within the bearing assembly leaks.
The ball bearing assembly of the present invention may include a plurality of balls interposed between inner and outer rings and retained by the cage and a sealing member provided in the outer ring for closing the bearing space; in which a shoulder portion is formed between a seal groove, formed at a location laterally of a raceway in the inner ring; the sealing member is mounted on an inner peripheral surface of the outer ring opposed to the seal groove and has an inner periphery side tip portion provided with the primary sealing lip and a labyrinth seal protruding upwardly of the shoulder portion; and the primary sealing lip is provided with an inner peripheral face opposed to the seal groove; and the labyrinth seal is provided with an inclined face having its diameter gradually increasing towards a tip portion of the labyrinth seal.
According to the construction described above, since the snap cage is provided with the previously described recessed areas, the grease leakage from the cage back face side can be suppressed. Accordingly, deposition of the grease onto the cage outer diametric portion or the like can be avoided. Also, since the inner peripheral portion of the sealing member is provided with the primary sealing lip and the labyrinth lip and since the primary sealing lip is provided with an inner peripheral face held in opposition to the seal groove and the inner periphery of the labyrinth lip is formed with an inclined face, the tip portion of the primary sealing lip, which is a contact seal, can be caused to contact the raceway side groove wall of the seal groove at a contact position lower than the upper end position of the shoulder portion side groove wall opposed to the raceway side groove wall of the seal groove. Accordingly, muddy water then scattered will not directly reach the tip portion of the sealing lip. Therefore, even when this bearing assembly is used under the environment in which muddy water or the like scatters, the tip portion of the sealing lip can be brought into stable contact with the raceway side groove wall of the seal groove, allowing the sealing property of the contact seal to be exhibited sufficiently. Thus, not only can the grease leakage within the bearing assembly be prevented, but the resistance to muddy water can also be obtained. Therefore, since there is no need to increase the tightening force of the sealing lip or the like, the low bearing torque can be accomplished.
A method of making a cage of the present invention for a ball bearing assembly may include the steps of forming a pawl component separately from and independent of a cage body, the pawl component having pawl tip portions of pawls protruding at least from pawl portions on a cage inner diametric side of respective pawl portions on a cage outer diametric side; and bonding, fusion bonding or mounting the pawl component on the cage body after the cage body has been assembled in inner and outer rings and balls of the ball bearing assembly.
According to the method described above, at the time of incorporation of the cage, occurrence of the blanching and/or the fracture at the root of the pawls can be avoided.
A method of manufacturing the cage of a different construction according to the present invention for a ball bearing assembly may include the steps of manufacturing a half-finished cage component, in which pawl tip portions of pawls protruding at least from pawl portions on a cage inner diametric side of respective pawl portions on a cage outer diametric side are spaced from a center of each of pockets an extent larger than those assumed when completed, to assume an opened posture; and effecting a thermal deformation or a secondary processing to allow the pawl tip portions to assume a closed posture to follow a corresponding ball surface after the cage body has been assembled in inner and outer rings and balls of the ball bearing assembly.
According to the method described above, during incorporation of the cage, occurrence of the blanching and/or fracture at the root of the pawls can be avoided.
In any event, the present invention will become more clearly understood from the following description of preferred embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and:
1: Ball bearing assembly
2: Inner ring
2
a: Raceway surface
2D: Inner ring outer diametric surface
3: Outer ring
4: Ball
5: Cage
5A: Cage body
5B: Half-finished cage
6: Sealing member (Contact sealing member)
8Ab: Branched portion
8Ac: Primary sealing lip
8Ad: Auxiliary sealing lip
10: Seal groove
11: Pocket
12: Annular cage body
14: Tip portion (Pawl) of the pocket
14
a: Pawl on a cage inner diametric side
14
b: Pawl on a cage outer diametric side
14
ba: Pawl component (Pawl tip portion)
14A: Pawl component
16: Recessed area
Ln: Labyrinth lip
Lna: Inclined face
Lm: Primary sealing lip
Lmb: Inner peripheral surface
Ls: Labyrinth seal
S1: Contact sealing member
SL: Sealing lip segment
Tk: Projection
V1: Bearing space
A first preferred embodiment of the present invention will be described in detail with particular reference to some of the accompanying drawings.
As best shown in
A portion of the cage 5 is shown in a perspective view in
Each of the recessed areas 16 has an inner face of such a shape that the sectional shape taken along the direction circumferentially of the cage 5 (that is, the sectional shape in a plane perpendicular to the cage center axis) represents an arcuate shape of a radius of curvature Rb, which is smaller than the radius of curvature Ra of the concave spherical surface defining the inner face of each of the pockets 11 and, more specifically, represents, as best shown in
That pair of the recessed areas 16 are positioned symmetrically relative to each other at respective positions so selected that the angle of orientation in the circumferential direction of the cage 5 relative to the center OW11 of the cage circumferential direction at the open edge of each pocket 11 is within the range of 40°±15°. Each of those recessed areas 16 has a depth so selected that the distance Rc from the center O11 of the spherical surface depicted by each of the pocket inner faces to the deepest position of each of the recessed areas 16 is preferably equal to or greater than 1.05 times of the radius of each of the bearing balls 4.
It is to be noted that although in the illustrated embodiment reference has been made to the use of the pair of the recessed areas 16, three or more recessed areas may be employed.
It is to be noted that in the practice of the present invention, the sectional shape of each of the recessed areas 16 along the cage circumferential direction may not be necessarily limited to that described in connection with any one of the respective examples shown in and described with reference to
It is to be noted that although in the embodiment shown in
In avoiding the grease leakage, it is important that the axial position of one end on the back face side of the inner diametric surface of each of the bridge portions 13, which is left unremoved, should lie on an intermediate side of the raceway surface 2a of the inner ring 2, rather than a shoulder of the raceway surface 2a of the inner ring 2, as viewed in the section at the intermediate position in the circumferential direction of the bridge portions 13 each defined between the neighboring pockets 11 and 11. This is shown in
Also, the position of Yb in that figure is the position on the back face side where the inner diametric surface of the bridge portion 13 may exist, and an outer wall face extending to the same position as the axial position on the back face side at the center of each pocket 11 may exist on an outer diametric side thereof. Similarly, it may be so shaped that the axial thickness of each bridge portion 13 as measured from the position of Yb to the outer diametric side may gradually or stepwise increase towards the back face side.
It is to be noted that in order to reduce the surface area of the inner diametric surface of the cage 5, each of the recessed areas 16 employed in the inner surface of the corresponding pocket 11 may be increased as shown in
It is also to be noted that as shown in
A sixth preferred embodiment of the present invention is shown in
The results of the tests shown respectively in
As can readily be understood from the results of those tests, in the cage 5 for the ball bearing assembly according to this embodiment, as a result that the recessed areas 16 extending from the pocket open edge on the cage inner diametric side towards the cage outer diametric side are provided on the inner faces of the pockets 11, the amount of grease deposited on the balls 4 and scraped therefrom by the inner diametric surface of the cage 5 decreases. Accordingly, it is possible to avoid the grease deposition onto the outer diametric portion of the inner ring 2. Absent the grease deposition onto the outer diametric portion of the inner ring 2, flow of the grease into the seal groove 10 (
If in the snap cage is adopted the grease leakage preventive structure of the prior art cage (disclosed in the Patent Document 4 referred to previously), in which the radius of the inner diameter of a circumferential portion, where each of the pockets is defined, as measured from the cage center is chosen to be greater than the radius of a circumferential portion, which is delimited between the neighboring pockets, as measured from the cage center, the shape of a circumferential intermediate bottom portion of each of the pockets need be removed partially. For this reason, the strength of the cage is considerably lowered, making it possible to be placed on practical use. More specifically, when the centrifugal force brought about by rotation of the cage works, the strain at the intermediate bottom portion of some of the pockets will become large, resulting in fracture of that portion or an increase of the amount of displacement towards the outer diametric side of the corresponding bridge portion between the neighboring pockets, to such an extent as to result in an undesirable contact with the outer ring. In contrast thereto, the recessed areas 16 employed in the cage 5 according to this embodiment are effective to minimize the decrease of the strength of the cage 5 since they do not exist at the bottoms of the pockets 11, and, therefore, it can withstand the practical use.
In each of the various embodiments hereinabove described, the preferred position where the recessed areas 16 are defined in the inner face of each of the pocket 11 is that indicated by the symbol P in
The inner face shape of the recessed area 16 is represented by a cylindrical surface extending substantially along the imaginary cylinder VC having its center lying on the straight line LC extending radially of the cage 5 as best shown in
The recessed area 16 preferably has such a depth that the distance RCc from the center O11 of the spherical surface defining the pocket inner face to the deepest position of the recessed area 16 is of a value equal to or greater than 1.05 times the radius of each of the balls 4. The radius of curvature Ra of the spherical surface defining the inner face of each of the pocket 11 is slightly greater than the radius of each of the balls 4 and is not greater than 1.05 times the radius of each of the balls 4.
In a single row deep groove ball bearing assembly 1 (
According to this double row ball bearing assembly 31, since the cage 5 according to the embodiment of the present invention is incorporated therein with the rear side having the grease leakage preventive function oriented towards the contact sealing member 6, it is possible to suppress the leakage of the grease from both sides of the ball bearing assembly 31.
Hereinafter, the cage for the ball bearing assembly of a type, which can be used under a higher speed rotation than that of the conventional case while the grease leakage is suppressed, will be discussed. In the description that follows, component parts similar to those described in connection with any one of the foregoing embodiments described hereinbefore are designated by like reference numeral and the details thereof are not reiterated for the sake of brevity. In the case that only a part of structures is explained, other structural features are similar to those of the forgoing embodiments. Not only can a combination of the component parts specifically described in connection with any one of the foregoing embodiments described hereinbefore be employed, but also a combination of some of the foregoing embodiments described hereinbefore can be partially employed provided that such combination poses no problem.
The snap cage according to an eighth preferred embodiment of the present invention shown in
The snap cage according to a ninth preferred embodiment of the present invention shown in
The snap cage according to a tenth preferred embodiment of the present invention shown in
The snap cage shown in
The snap cage according to an eleventh preferred embodiment of the present invention shown in
As shown in
The snap cage shown in
Here, a sectional view of the ball bearing assembly provided with the standard sealing members is shown in
In order to further reduce the stress concentration and the displacement, as shown in
In the meantime, with the shape shown in
In the cage shown in and described with particular reference to
In the case of the cage shown in and described with reference to
In the case of the cage shown in and described with reference to
In the next place, the analysis on the rolling element delayed advance will be discussed.
The configuration of the cage capable of a high speed rotation is effective to relieve the stress concentration even when the delayed advance of the rolling elements occurs.
Also, the increased wall thickness of the pocket bottom face and the use of the reinforcement portion lead to reduction of the maximum value of the stress concentration, accompanied by reduction of the displacement amount. Since the stress occurring in the pawl portion shown in
As shown in
The ball bearing assembly of the present invention may be adopted in an automobile auxiliary equipment.
The ball bearing assembly of the present invention may also be adopted in a motorcycle gear reduction unit.
For example, as shown in
A planetary gear mechanism 60, shown on an enlarged scale in
Also, as shown in
The following summarizes the various preferred embodiments of the present invention which have been shown in and described with reference to
The cage for the ball bearing assembly, which forms a basic construction in each of the following modes, is of such a design that in the snap cage for the ball bearing assembly including the annular cage body having one side face opened partly for holding the balls within the respective pockets, the inner face of each of those pockets is provided with the recessed areas each extending from the pocket open edge on the cage inner diametric side towards the cage outer diametric side.
In the basic construction described above, the inner face of each of the pockets represents a concaved spherical shape and the sectional shape of the inner face of each of the recessed areas sectioned in the cage circumferential direction may be an arcuate shape of a radius of curvature smaller than the radius of curvature of the concaved spherical surface defining the inner face of each of the pocket is.
In the basic construction described above, the sectional shape of the inner face of each of the recessed areas sectioned in the cage circumferential direction may be a polygonal shape.
In the basic construction described above, the inner face of each of the pockets may represent a concaved spherical shape and each of the recessed areas may have a depth so chosen that the distance from the center of the concaved spherical surface of the pocket inner face to the deepest position of the respective recessed area may be equal to or greater than 1.05 times the radius of each of the balls.
In the basic construction described above, the axial thickness of each of the bridge portions on the cage outer diametric side in the section at the position intermediate of the cage circumferential direction may be so chosen as to be greater than the axial thickness on the cage inner diametric side. By so doing, it is possible to secure the strength of the cage while the surface area of the inner diametric surface of each of the bridge portions is reduced.
In the construction described above, there may be provided the recessed areas in the rear face of each of the pockets, each area extending from the cage inner diametric edge to the cage outer diametric side. By so doing, the surface area of the inner diametric surface in each of the pockets can be reduced to increase the effect of avoiding the grease leakage.
In the basic construction described above, the axial thickness of each of the pocket shells at the cage outer diametric side may be greater than the axial thickness at the cage inner diametric side. By so doing, while the surface area of the inner diametric surface at each of the pocket shells is reduced, the strength of the cage can be secured.
In the basic construction described above, the amount of projection of the cage outer diametric side tip portion at the open edge tip portion of each of the pockets in the axial direction may be shorter than the amount of projection of the cage inner diametric tip portion in the axial direction. By so doing, the cage can have a reduced weight and, when the ball bearing assembly is used at the high speed rotation, the stress of the cage caused by the centrifugal force can be reduced. During the high speed rotation, the tip portion of the cage tends to be deformed so as to tilt towards the outer diametric side relative to the center portion of each of the pockets and thus, the balls are guided at the inner diametric side of the tip portion and, therefore, the bearing functionality will not be adversely affected even when the outer diametric side of the tip portion is partly removed.
The cage with the basic construction described above may be used in a ball bearing assembly that is employed in an automobile auxiliary equipment.
In the case of the single row ball bearing assembly, the behavior of the grease towards the pocket open edge side makes no difference with that observed in the ball bearing assembly of the type employing the standard snap cage and, therefore, the effect of avoiding the grease leakage cannot be expected. However, it is quite often that the ball bearing assembly is generally employed in a pair and the grease leakage towards the opposite end side of the pair of the ball bearing assemblies is often disliked. In such case, if the cage of the above described invention for use in the ball bearing assembly is incorporated with the back face side thereof oriented towards the side where the grease countermeasure is desired to be applied, the grease sealing function of the final product can be maintained.
In the ball bearing assembly equipped with the cage of the basic construction described above, where a double rows are employed, the cage for the ball bearing is preferably incorporated in the plural row ball bearing assembly in such a manner that the back face side having the grease leakage preventive function may be oriented towards the bearing outer side. By so doing, the grease leakage from the opposite sides of the double row ball bearing assembly can be suppressed.
In the ball bearing assembly including the cage of the basic construction described above, the grease filling percentage may not greater than 100% relative to the space bound by a sealed plate inner side of the ball bearing assembly and the inner and outer rings thereof. Assuming that the space bound by the sealed plate inner side and the inner and outer rings of the ball bearing assembly is the total spatial capacity, a space represented by the total spatial capacity excluding the space, within which the balls and the cage undergo rotation during rotation of the ball bearing assembly, is referred to as a “stationary space”. If the grease filling percentage is not greater than 100% relative to the stationary space between the inner and outer rings, the possibility of the filled grease undesirably leaking from the radial gap delimited between the sealed plate inner diametric surface and the outer ring inner diametric surface can be suppressed.
The amount of projection of each of the first pawl portions 14a on the cage inner diametric side is chosen to be equal to the amount of projection of the pawl found in the standard snap cage, but the amount of projection of the respective second pawl portion 14b on the cage outer diametric side is chosen to be longer than that of each first pawl portion 14a on the cage inner diametric side. More specifically, as shown in
Also, the width of the second pawl portion 14b on the cage outer diametric side in the cage radial direction is preferably so chosen as shown in
In general, assemblage of the ball bearing assembly utilizing the standard snap cage is carried out by incorporating the cage into the ball bearing assembly after the balls have been positioned between the inner and outer rings. Where the snap cage is made of a resinous material, and if the distance between the respective tips of the pair of the pawls in each of the pockets is equal to or smaller than 90% of the radius of each of the balls, a contorted force will act on the pawls during assemblage of the balls into the cage and, therefore, there is a high possibility that blanching and/or fracture will occur at respective roots of the pawls. In this embodiment, the distance between the respective tips of the second pawl portions 14b on the cage outer diametric side will become narrower than 90% of the radius of each of the balls 4. For this reason, it will be difficult to incorporate the cage 5, as completed, after the balls 4 have been assembled into the ball bearing assembly 1.
In view of the above, in this embodiment, the cage 5 for use in the ball bearing assembly is manufactured by means of process steps shown in any one of
The manufacturing method shown in
The behavior of the grease in the ball bearing assembly utilizing the cage 5 for the ball bearing assembly according to this embodiment will now be described with particular reference to
Referring now to
Referring to
From the foregoing results of the tests, it is preferred that as the shape of the pawl 14 effective to exert an effect of suppressing the grease leakage, the angle θb of the second pawl portion 14b on the cage outer diametric side as shown in
From the results of those tests shown respectively in
As can readily be understood from those results of the tests, with the cage 5 designed according to the twelfth embodiment of the present invention, in view of the fact that the distance between the tips of the respective second pawl portions 14b of the pair of the pawls 14 of each of the pockets 11 on the cage outer diametric side was chosen to be smaller than the distance between the tips of the respective first pawls 14a of the pair of the pawls 14 of each of the pockets 11 on the cage inner diametric side, the grease deposited on the corresponding ball 4 was not allowed to flow from the outer ring side towards the outer diametric portion of the inner ring and even the grease from the inner ring side could be scraped by the second pawl portions 14b on the cage outer diametric sides that are distant from the outer diametric portion of the inner ring and, as a result, the grease leakage from the ball bearing assembly 1 could be avoided.
In the twelfth embodiment described hereinabove, as the shape of each of the pawls 14, reference has been to the amount of projection of the first pawl portion 14a on the cage inner diametric side and that of the second pawl portion 14b on the cage outer diametric side, which progressively change. If, however, the amount of projection of the pawl tip portion on the cage outer diametric side is longer than that of the pawl tip portion on the cage inner diametric side, the shape of each of the pawls 14 may be of any suitable shape, provided that it is held in non-contact relation with the inner and outer rings 2 and 3 and the contact sealing members 6 (
Then, after the cage body 5A has been assembled in the inner and outer rings 2 and 3 and the balls 4 of the ball bearing assembly 1, as shown in
Unlike any one of the embodiments shown in and described with particular reference to
In the manufacturing method shown in and described with reference to
In the manufacturing method of the kind discussed above, the pawl component may be a component of a toric shape straddling continuously over the plural pockets. In the case of this construction, with component parts of a number smaller than the number of the pockets, a portion on the cage outer diametric side can be afforded, facilitating the assemblage along with reduction in manufacturing cost.
In the next place, the composition of grease filled in the bearing space V1 (
As a result of a surface analysis conducted on a bearing rolling surface, it has been revealed that addition of the additive of the aluminum series allows an aluminum compound to react in a frictionally worn surface or a newly existing surface of a metal that is exposed as a result of frictional wear to thereby generate an aluminum coating on a bearing rolling surface together with an ferric oxide. It appears that the ferric oxide and the aluminum coating, formed on the bearing rolling surface, are effective to suppress generation of hydrogen resulting from decomposition of the grease composition to thereby avoid a peculiar exfoliation, which would be caused by hydrogen brittleness and, therefore, the service lifetime of the rolling bearing assembly can be prolonged.
The aluminum series additive to be added to the grease composition is at least one selected from the group consisting of an aluminum powder and an aluminum compound. For the aluminum compound, examples include inorganic aluminum such as, for example, aluminum carbonate, aluminum sulfide, aluminum chloride, aluminum nitrate and hydrates thereof, aluminum sulfate, aluminum fluoride, aluminum bromide, aluminum iodide, aluminum oxide and hydrates thereof, aluminum hydroxide, aluminum selenide, aluminum telluride, aluminum phosphate, aluminum phosphide, lithium aluminate, magnesium aluminate, aluminum selenate, aluminum titanate, aluminum zirconate and so on; and organic aluminum such as, for example, aluminum benzoate, aluminum citrate and so on. One or two of those aluminum series additives may be mixed and then added to the grease. In the practice of the present invention, the use of the aluminum powder having a high extreme pressure effect is preferred because it has a high heat resistance and a high durability and is hard to be thermally decomposed.
The amount of the aluminum series additive to be added is within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the base grease. Specifically, (1) where the aluminum series additive is solely the aluminum powder, the aluminum powder is added in an amount within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the base grease; (2) where the aluminum series additive is solely the aluminum compound, the aluminum compound is added in an amount within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the base grease; and (3) where the aluminum series additive is a mixture of the aluminum powder and the aluminum compound, the total amount of the aluminum powder and the aluminum compound that are added is within the range of 0.05 to 10 parts by weight relative to the 100 parts by weight of the base grease. If the mixing proportion of the aluminum series additive is smaller than the lower limit referred to above, exfoliation, which would occur at the raceway surface as a result of the hydrogen brittleness, cannot be effectively avoided. On the other hand, no further effect of avoiding the exfoliation can be expected if the mixing proportion thereof exceeds the upper limit referred to above.
For a base oil of the above mentioned grease composition that can be employed in the practice of the present invention, examples include mineral oil such as, for example, a spindle oil, a refrigerator oil, a turbine oil, a machine oil, a dynamo oil and so on; a synthesized oil of the hydrocarbon series such as, for example, a high refined mineral oil, liquid paraffin, polybutene, a GTL oil synthesized by means of the Fisher-Tropsch process, a poly-α-olefin oil, alkylnaphthalene, alicyclic compounds and so on; and a synthesized oil of the non-hydrocarbon series such as, for example, natural fat and oil, a polyol ester oil, a phosphate ester oil, a polymer ester oil, an aromatic ester oil, a carbonic acid ester oil, a diester oil, a polyglycol oil, a silicone oil, a polyphenylether oil, an alkyl diphenylether oil, alkyl benzene oil, fluorinated oil and so on. Of them, the use of the alkyl diphenylether oil or the poly-α-olefin oil is preferred because it has an excellent heat resistance and an excellent lubricity.
Of the grease composition referred to above, the thickener that can be employed in the practice of the present invention includes benton; silica gel; fluorine compounds; soaps such as, for example, lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, aluminum complex soap and so on; and compounds of the urea series such as, for example, diurea compounds, a polyurea compounds and so on. Of those thickeners, the use of the compounds of the urea series is preferred in terms of the heat resistance and the cost. The compounds of the urea series can be obtained by reacting an isocyanate compound with an amine compound. In order to avoid leftover of an reactive free radical, it is preferred that the isocyanate group of the isocyanate compound and the amino group of the amine compound are blended in substantially equivalent weight.
The diurea compound referred to above can be obtained by reacting, for example, diisocyanate and monoamine with each other. For the diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate and others can be enumerated. For the monoamine, octyl amine, dodecyl amine, hexadecyl amine, stearyl amine, oleyl amine, aniline, p-toluidine, cyclohexylamine and others can be enumerated. The polyurea compound can be obtained by reacting, for example, diisocyanate, monoamine and diamine with each other. For the diisocyanate and monoamine, compounds similar to those used in preparing the diurea compound can be enumerated, and for the diamine, ethylene diamine, propane diamine, butane diamine, hexane diamine, octane diamine, phenylene diamine, tolylene diamine, xylene diamine, diamino diphenylmethane and others can be enumerated.
When the thickener such as, for example, the compound of the urea series is blended in the base oil, the base grease necessary to blend the additive of the aluminum series referred to above can be obtained. The base grease of a kind, in which the compound of the urea series is used as the thickener, is prepared by reacting the isocyanate compound and the amine compound with each other in the base oil. The mixing proportion of the thickener in 100 parts by weight of the base grease is preferably within the range of 1 to 40 parts by weight and, more preferably, within the range of 3 to 25 parts by weight. If the amount of the thickener contained therein is smaller than the lower limit of 1 part by weight referred to above, the recruiting effect will be lowered and formation of the grease will become difficult, but if it exceeds the upper limit of 40 parts by weight, the resultant base grease will become hard and no expected effect can be obtained.
Also, in addition to the aluminum series additive, any known additive for use with the grease may be employed as necessary. For this additive, for example, organic zinc compounds, antioxidants such as, for example, compounds of the amine series or of the phenol series, a metal inert agent such as, for example, benzotriazole, a viscosity index increasing agent such as, for example, polymethacrylate or polystyrene, a solid lubricant such as, for example, molybdenum disulfide or graphite, antirust agent such as, for example, metal sulfonate or polyol ester, a friction reducing agent such as, for example, organic molybdenum, an oily agent such as, for example, ester or alcohol, and/or a frictional wear preventing agent such as, for example, compounds of the phosphorous series. Those additives may be employed singly or in combination of two or more of them. The grease composition of the present invention is effective to avoid an undesirable occurrence of the peculiar exfoliation caused by the hydrogen brittleness and, therefore, the service lifetime of the grease filled bearing assembly can be increased.
4,4-diphenyl methane diisocyanate (tradenamed “MILLIONATE MT” manufactured by and available from Nippon Polyurethane Industry Co., Ltd.) (hereinafter referred to as “MDI”) was dissolved in a quantity, listed in Table 2 below, into half the amount of the base oil listed also in Table 2, and a quantity of monoamine which is twice equivalent to MDI, was dissolved into the remaining amount of the base oil. Their blending proportions and types are as tabulated in Table 2. After a solution of monoamine dissolved therein had been added while the solution containing MDI dissolved therein was stirred, the resultant solution was reacted at a temperature within the range of 100 to 120° C. for 30 minutes while being stirred, to form the diurea compound in the base oil. Respective proportions of the aluminum series additive and the antioxidant, as shown in Table 2, were then added to the base oil containing the diurea compound and stirred at a temperature within the range of 100 to 120° C. for 10 minutes. The resultant solution was then cooled and homogenized with the use of three rolls to thereby provide the grease composition.
In Table 2, the synthetic hydrocarbon oil used as the base oil utilized “SYNFLUID 601” (manufactured by and available from Nippon Steel Chemical Co., Ltd.) having a dynamic viscosity of 30 mm2/sec. at 40° C. and the alkyl diphenyl ether oil utilized “MORESCOHIGHLUB LB 100” (manufactured by and available from Matsumura Sekiyu Kabushiki Kaisha) having a dynamic viscosity of 97 mm2/sec. at 40° C. Also, the antioxidant was employed in the form of “HINDERED PHENOL” (manufactured by and available from Sumitomo Chemical Co., Ltd. A rapid acceleration and deceleration test was conducted on the resultant grease composition. The test method and test conditions are discussed below. Results are shown in Table 2.
The rapid acceleration and deceleration test was conducted by imitating an alternator, which is one example of auxiliary equipments for an electric appliance, and filling the grease composition in a deep groove ball bearing assembly 6303 of an inner ring rotating type used to support a rotary shaft. This test was conducted under test conditions in which the load loaded to a pulley fitted to a rotary shaft tip was 1960 N, the rotational speed was set to a value within the range of 0 to 18,000 rpm. while an electric current of 0.1 A flowed inside the bearing assembly tested. Also, the length of time (exfoliation occurrence lifetime, h) during which a power generator halted as a result those vibrations in a vibration detector attained a value higher than a preset value subsequent to occurrence of an abnormal exfoliation within the bearing assembly, was measured. It is to be noted that the test was interrupted upon elapse of 500 hours.
In a manner similar to the method in Example 1 above, using the blending proportions shown in Table 2, the base grease was adjusted by selecting the thickener and the base oil, followed by addition of the additive to obtain the grease composition. The resultant grease composition was tested and evaluated in a manner similar to that in Example 1 above. Results thereof are shown in Table 2.
(1) SYNFLUID 601 (of Nippon Steel Chemical Co., Ltd. and having a dynamic viscosity of 30 mm2/sec. at 40° C.).
(2) MORESCOHIGHLUB LB100 (of Matsumura Sekiyu Kabushiki Kaisha and having a dynamic viscosity of 97 mm2/sec. at 40° C.
(3) MILLIONATE MT (of Nippon Polyurethane Industry Co., Ltd.)
(4) HINDERED PHENOL (of Sumitomo Chemical Co., Ltd.)
(5)~(7) Reagent
As shown in Table 2, each of the Examples discussed above exhibited excellent test results (of the rapid acceleration and deceleration test), that is, 400 hours or more (exfoliation occurrence lifetime). This appears to have resulted from the fact that thanks to the addition of the predetermined amount of the aluminum series additive, the peculiar exfoliation accompanying a change in whitened texture occurring on the raceway surface could be avoided effectively.
According to the ball bearing assembly 1 having the grease composition filled in the previously described bearing space V1 (
Since with the cage of the type provided with the recessed areas 16 the leakage of the grease can be avoided, there is no need to change the shape of the seal groove 10 in the inner ring 2 and there is also no need to provide, for example, a slinger or the like in the axial direction of the bearing assembly. Accordingly, the space saving can be realized with no need to increase the number of component parts. Since by adopting the cage 5 of the type described above and the grease composition of the kind described above, the bearing assembly can be operated under a feasible condition without the hydrogen brittleness and there is no grease leakage occurring, the lubricating duration characteristic possessed by the grease filled in the bearing space V1 can be sufficiently exhibited. Also, contamination of the external environment resulting from the grease leakage and obnoxious noises generated as a result of corrosion and/or slippage of, for example, an engine auxiliary machine belt or the like can be avoided. In addition, as compared with that in the conventional case, reduction in manufacturing cost brought about by reduction in number of component parts can be expected.
The following summarizes various preferred modes of the ball bearing assembly having the grease composition filled in the previously described bearing space V1 (
The ball bearing assembly, which forms a basic construction in each of the following modes, is of a structure including the cage of the present invention, a plurality of balls retained by this cage and interposed between the inner and outer rings, the grease composition being filled in the bearing space between the inner and outer rings, and sealing members provided in the outer ring or the inner ring for sealing the bearing space, in which the grease composition is filled in the bearing space and is prepared by blending an additive in a base grease containing a base oil and a thickener, the additive containing at least one aluminum series additive which is selected from the group consisting of an aluminum powder and an aluminum compound, with the amount of the aluminum series additive being within the range of 0.05 to 10 parts by weight relative to 100 parts by weight of the base grease.
In the basic construction described above, as the thickener, a urea series thickener can be enumerated.
In the basic construction described above, the base oil referred to above is selected from the group consisting of an alkyldiphenyl ether oil and a poly-α-olefin oil.
The ball bearing assembly of the basic construction described above may be a double row angular contact ball bearing assembly including an outer ring having an inner periphery formed with double rows of raceway surfaces, an inner ring having raceway surfaces formed in an outer periphery thereof in face-to-face relation with the above described raceway surfaces, double rows of balls interposed between the raceway surfaces in the inner ring and the raceway surfaces in the outer ring, a cage for retaining the balls for each row, and sealing members provided in the outer ring or the inner ring for closing a bearing space delimited between the inner ring and the outer ring.
A thirteenth preferred embodiment of the present invention will now be described with particular reference to
A counterbore portion forming an inner ring outer diametric surface on the left side of
The sealing member 6 will be described in detail.
As shown in
A portion is so formed as to extend straight from the constricted area 8Aa in the inner diametric direction and a branched portion 8Ad is provided at a location partway thereof. A portion extending from the branched portion 8Ab in the inner diametric direction forms a primary sealing lip 8Ac and a portion parting therefrom in an inwardly oriented axial direction forms an auxiliary sealing lip 8Ad. The primary and auxiliary sealing lips 8Ac and 8Ad are continued to each other at the branched portion 8Ab so as to represent a shape similar to the inverted shape of a figure “L”. The branched portion 8Ab referred to above lies within the range, in which a line of extension of the thickness of the primary sealing lip 8Ac and a line of extension of the auxiliary sealing lip 8Ad intersect with each other and is defined by a portion encompassed by the single dotted circle line in
The step referred to above does not pose an obstruction to the grease then moving from the side of the inner ring outer diametric surface 2D towards the side of the auxiliary sealing lip 8Ad as shown by the arrow a in
As shown in
While the primary and auxiliary sealing lips 8Ac and 8Ad in
In the case of this invention, by the following reasons, the interference of the contact seal S1 can be further reduced. The first reason is that a portion of the grease purged from the raceway surface 2a towards the outside through the inner ring outer diametric surface 2D moves on the outer diametric surface of the auxiliary sealing lip 8Ad as shown by the arrow in
Another reason is that the grease reservoir Gd is formed by the primary and auxiliary sealing lips 8Ac and 8Ad, which are continued to each other through the branched portion 8Ab so as to represent a shape similar to the inverted shape of a figure “L” as hereinbefore described, and the inner groove wall 10b of the seal groove 10 opposed thereto and has a relatively large capacity. Accordingly, the internal pressure of the grease reservoir Gd can be further reduced.
In order to ascertain the function and effect described above, a test was conducted to compare the article of the present invention according to the thirteenth embodiment (an article having opposite seals) and the currently available article of the structure described subsequently.
The primary and auxiliary sealing lips are so designed and so shaped as to occupy respective arms formed by ramifying the tip portion of a synthetic rubber forming a sealing member. The currently available article is structured by positioning the primary sealing lip, which is defined by one of the ramified arms, on an inner side and positioning the auxiliary sealing lip, which is defined by the other of the ramified arms, on an outer side. (The article having opposite seals)
Using the article of the present invention and the currently available article of the structure described above, the torque value was measured under the axial loading of 4 kgf. Actually measured values are shown in
Regarding the torque values shown in
According to the ball bearing assembly 1 designed in accordance with the thirteenth embodiment of the present invention, the recessed areas 16 are provided in the snap cage 5 and the amount of grease sticking to the balls 4 and scraped therefrom by the inner diametric surface 5d of the cage 5 can be reduced. Accordingly, deposition of the grease onto the outer diametric portion 2D of the inner ring 2 can be avoided. Therefore, deposition of the grease onto the seal groove 10 in the inner ring 2 can be avoided. There is no need to change the design and the shape of the seal groove 10 and, also, to secure a space for installation of a slinger or the like. Accordingly, the manufacturing cost can be reduced with the number of component parts reduced as compared with the conventional example.
Also, in the sealing member 6, the grease is sealed by the labyrinth seal Ls, formed by the auxiliary sealing lip 8Ad, and the contact seal S1 formed by the primary sealing lip 8Ac, and leakage thereof to the outside is prevented. Since the outer diametric surface of the auxiliary sealing lip 8Ad spreads axially to a height about equal to the inner ring outer diametric surface 2D, the grease thrust from the side of the raceway surface 2a smoothly move towards the outer diametric surface side thereof. Therefore, the amount of the grease passing through the labyrinth seal Ls can be reduced. The internal pressure of the bearing assembly is relieved by the auxiliary sealing lip 8Ad and the internal pressure acting on the primary sealing lip 8Ac is reduced. Therefore, the interference of the contact seal S1 formed by the primary sealing lip 8Ac can be reduced to achieve the low torque.
Because of the recessed areas 16, the amount of the grease sticking to the balls 4 and scraped therefrom by the cage inner diametric surface 5d is reduced. By the recessed areas 16, the grease tending to pile up in the vicinity of the pocket open edge of the cage 5 can be caused to smoothly flow onto the inner surface of each of the pocket 11, thus contributing to the lubrication.
The sealing member 6 forms the grease reservoir Gd, which is surrounded by the primary and auxiliary sealing lips 8Ac and 8Ad, which are shaped to represent the inverted L shape through the branched portion 8Ab, and the inner side wall 10b of the seal groove 10, and which is communicated with the bearing interior through the labyrinth seal Ls and is closed at the contact seal S1. Since this grease reservoir Gd function to further relieve the internal pressure of the bearing assembly, the interference of the primary sealing lip 8Ac can be reduced to achieve a low torque and, at the same time, a high sealing can be achieved.
The counterbore portion forming the inner ring outer diametric surface on the left side of
In the single row angular contact ball bearing assembly according to the fourteenth preferred embodiment of the present invention shown in
According to the construction shown in and described with reference to
As is the case with the single row angular contact ball bearing assembly according to a fifteenth preferred embodiment of the present invention shown in
The ball bearing assembly according to a sixteenth preferred embodiment of the present invention shown in
According to this double row angular contact ball bearing assembly, since the recessed areas 16 are provided in each of the snap cages 5 and the respective pocket front surfaces of those two cages 5 and 5 are arranged so as to confront with each other, the leakage of the grease from the cage back face side is suppressed. Accordingly, the grease can be prevented from sticking to the outer diametric portion 2D of the inner ring 2. Therefore, not only can the deposition of the grease in the seal groove 10 of the inner ring 2 be avoided, but also there is no need to change the design and the shape of the seal groove 10 and also to use a space for installation of a slinger or the like. Accordingly, the manufacturing cost can be lowered with the number of component parts reduced to a small number as compared with those in the conventional example.
Also, in the sealing member 6, the grease is sealed by the labyrinth seal Ls, formed by the auxiliary sealing lip 8Ad, and the contact seal S1 formed by the primary sealing lip 8Ac, and leakage thereof to the outside is prevented. Since the outer diametric surface of the auxiliary sealing lip 8Ad spreads axially to a height about equal to the inner ring outer diametric surface 2D, the grease thrust from the side of the raceway surface 2a smoothly move towards the outer diametric surface side thereof. Therefore, the amount of the grease passing through the labyrinth seal Ls can be reduced. The internal pressure of the bearing assembly is relieved by the auxiliary sealing lip 8Ad and the internal pressure acting on the primary sealing lip 8Ac is reduced.
In the double row angular ball bearing assembly, due to the cage shape, the deposition of the grease on the inner ring outer diametric portion 2D is suppressed and the leakage of the grease from the cage back face side, that is, from a counter-pocket side can be suppressed. In addition, by the use of the above described sealing members 6, the low torque and the high sealability can be realized, which are brought about by the labyrinth structure.
The rolling bearing assembly according to a seventeenth preferred embodiment shown in
The seventeenth preferred embodiment of the present invention will now be described in detail with reference to
The sealing structure according to the seventh embodiment best shown in
The auxiliary sealing lip 8Ad has an inner diametric face inclined at a predetermined angle α (for example, within the range of 5° to 10°) relative to the inner ring outer diametric surface 2D, and a labyrinth seal Ls is formed between the inclined face 8Adb and the inner groove wall 10b of the seal groove 10.
A tapered face 8Acc is also formed in the tip portion inner face of the primary sealing lip 8Ac, and the angle defined between the tapered face 8Acc and the outer groove wall 10c of the seal groove 10 is so formed as to be of a value equal to or larger than 90°. In the presence of such a large angle β, as compared with the case of the narrow angle β′ of not greater than 90° as shown in
In the sealing structure according to the seventeenth embodiment shown in and described with reference to
Examples of the present invention suggested for reference purpose will now be described with particular reference to
As shown in
The example suggested for reference purpose shown in
The above described example suggested for reference purpose differs considerably from the previously described embodiment in that the auxiliary sealing lips 8Ad1 to 8Ad3 (i.e., labyrinth seals Lsa to Lsc) exist at the respective positions; the capacity of the grease reservoir defined between the auxiliary sealing lips 8Ad1 to 8Ad3 and the groove wall of the seal groove 10 opposed thereto and between the primary sealing lip 8Ac and the groove wall of the seal groove 10 opposed thereto is small; and the amount of projection of the auxiliary sealing lip 8Ad1 in the axial direction is so small and the base of the auxiliary sealing lip 8Ad1 is continued to the inner face of the synthetic rubber 8A inclined inwardly.
In this example suggested for reference purpose, the torque value D measured when the interference of the primary sealing lip 8Ac is set to be about equal to that in the previously described embodiment, has been ascertained to be about equal to the torque value A exhibited by the article of the present invention as shown in
The following summarizes the various embodiments shown in and described with reference to
The ball bearing assembly, which forms a basic construction in each of the following modes, is of a structure including the cage of the present invention, a plurality of balls retained by this cage and interposed between the to inner and outer rings, and a sealing member for closing the bearing space between the inner and outer rings, in which a seal groove is formed in the outer diametric surface of the inner ring in a direction circumferentially thereof; the sealing member has an outer peripheral edge fixed to the outer ring inner diametric surface opposed to the seal groove and also has an inner peripheral edge provided with a primary sealing lip and an auxiliary sealing lip, the primary sealing lip being held in contact with the seal groove to form a contact seal whereas the auxiliary sealing lip is brought to or proximate to the seal groove to form a labyrinth seal; a branched portion is provided in the sealing member at a position proximate to the height of an inner ring outer diametric surface, the primary sealing lip being formed by a portion of the branched portion protruding in an inner diametric direction; the primary sealing lip has a tip portion held in contact with an outer groove wall of the seal groove to form the contact seal whereas the auxiliary sealing lip is formed by another portion of the branched portion protruding in the axial direction; and a labyrinth seal is formed between the tip portion of the auxiliary sealing lip and the inner groove wall of the seal groove.
The ball bearing assembly of the above described basic construction is a double row angular contact ball bearing assembly of a structure, which is provided with the sealing member and the two snap cages each having a plurality of pockets, the pockets in one of the cages and the pockets in the other of the cages being so arranged as to oppose to each other.
According to this construction, since each of the snap cages is provided with a recessed area and the pockets in one of the cages and the pockets in the other of the cages being so arranged as to oppose to each other, the leakage of grease from the cage back face side is suppressed. Accordingly, deposition of the grease onto the inner ring outer diametric portion can be avoided and, also, prevention of the deposition of the grease in the seal groove in the inner ring can be expected.
In the basic construction described above, the sealing member may have the primary sealing lip and the auxiliary sealing lip, which are formed in an inverted L shape through the branched portion. A grease reservoir is surrounded by those lips and an inner side wall of the seal groove, which groove is opposed to the primary and auxiliary sealing lips, and is communicated with the inside of the bearing assembly via the labyrinth seal in one side and closed by the contact seal in another side. Since the grease reservoir functions to further relieve the internal pressure of the bearing assembly, the interference of the primary sealing lip can be reduced to achieve a low torque and, at the same time, a high sealing characteristic.
In the basic construction described above, the sealing member may be of such a design in which the radial of the maximum diametric portion of the auxiliary sealing lip is greater than the radial of the inner ring outer diametric, in which case a tip portion of this auxiliary sealing lip is formed with a tapered face inclined at an angle equal to or greater than 90° relative to the inner ring outer diametric surface. The provision of the tapered face is effective to shift the grease smoothly towards an outer diametric surface of the auxiliary sealing lip.
In the basic construction described above, the inner diametric surface of the auxiliary sealing lip may be inclined at a predetermined angle relative to the inner ring outer diametric surface so that a labyrinth seal can be formed between the inclined inner diametric surface of the auxiliary sealing lip and the inner side wall of the seal groove. In this way, the labyrinth seal can be easily formed by inclining the inner diametric surface of the auxiliary sealing lip and the grease leak pressure can be reduced thanks to the labyrinth seal so formed.
An eighteenth preferred embodiment of the present invention will be described with particular reference to
In this angular ball bearing assembly, the use of the sealing member 6, as will be detailed later, and the cage 5 of the present invention makes it possible to achieve a low torque, a resistance to the grease leakage, dust proofing and space saving and, at the same time, a low cost.
The details of the sealing member 6 will now be described.
As shown in
The sealing member 6 is in the form of an elastic body 8 made of a synthetic rubber and reinforced by a core metal 7 and is formed with a sealing lip SL at a portion of the elastic body 8 so as to extend radially inwardly. For the synthetic rubber used to form the elastic body 8, a hydrogen added nitryl rubber or ester resistant acrylic rubber can be employed. Since the hydrogen added nitryl rubber is excellent in heat resistance as compared with nitryl rubber generally used as a sealing member and it has no problem in respect of the chemical resistance thereof, not only can stabilized characteristics be maintained, but also it can be used at higher temperature. Since the ester resistant acrylic rubber is excellent in heat resistance as compared with the nitryl rubber as is the case with the hydrogen added nitryl rubber and the chemical resistance against chemicals such as, for example, an ester oil of the acrylic rubber and a compressor oil used in an air conditioner is increased, not only can stabilized characteristics be maintained, but also it can be used at higher temperature.
The sealing lip SL includes a lumber portion La at which the wall thickness of the elastic body 8 is small, a dust sealing lip Lb extending from one end portion of the lumber portion La in a direction axially outwardly, and a primary sealing lip Lc extending from that end portion of the lumber portion La in a direction inwardly therefrom and having its tip portion slidingly engageable with an inner side face 10b of the seal groove 10. As best shown in
The sealing member 6 so structured as hereinabove described is such that, when the sealing member 6 is engaged in the sealing member anchoring groove 9 in the outer ring 3, the tip portion of the primary sealing lip Lc is held in contact with the inner side face 10b of the seal groove 10 as shown in
In this condition, since an air passage Kt communicating the interior of the bearing assembly to the outside thereof is formed around the projection Tk and the difference in pressure between the inside and outside of the bearing assembly is removed, a suction phenomenon of the bearing assembly can therefore be avoided. Since the air passage Kt is formed only around the projection Tk, a portion of the tip portion of the primary sealing lip Lc, where no projection Tk exist, keeps contacting with the inner side face 10b of the seal groove 10 and, therefore, the sealability is secured. When the pressure difference between the inside and the outside of the bearing assembly is removed, the sealing lip SL immediately resume a normal condition, with reduction in sealability being minimized consequently.
If the contact between the projection Tk and the inner side face 10b of the seal groove 10 is lost because of the large pressure difference between the inside and the outside of the bearing assembly or the pressure difference between the inside and the outside of the bearing assembly is very small, as shown in
Because of the difference in contact pressure, the sliding resistance of the tip portion of the projection Tk becomes higher than that of the tip portion of the primary sealing lip Lc and, when under this sucked condition the bearing assembly is rotated, the projection Tk maintains the condition, in which it is in contact with the inner side face 10b of the seal groove 10 as shown in
According to the angular contact ball bearing assembly according to the above described eighteenth embodiment of the present invention, since the snap cage 5 is provided with the recessed areas 16, the amount of grease sticking to the balls 4 and scraped therefrom by the inner diametric surface of the cage 5 can be reduced. Accordingly, the grease deposition onto the outer diametric portion 2D of the inner ring 2 can be avoided. Therefore, deposition of the grease onto the seal groove 10 in the inner ring 2 can be avoided. There is no need to change the design and the shape of the seal groove 10 and, also, to secure a space for installation of a slinger or the like. Accordingly, the manufacturing cost can be reduced with the number of component parts reduced as compared with the conventional example.
Also, since in the sealing member 6, the previously described projection Tk is provided in the inner face of the sealing lip SL, once the suction phenomenon occurs, the sealing lip SL is urged in a direction axially inwardly of the bearing assembly as shown in
Further, as shown in
For this reason, the suction phenomenon can be avoided with the balance in pressure between the bearing inside and outside instantly maintained uniformly. The air passage Kta necessary to maintain this pressure balance is immediately closed if the balance in pressure between the bearing inside and outside is uniform, that is, no pressure difference is developed, and the sealing lip SL assumes a normal condition as shown in
Since the counterbore portion forming the inner ring outer diametric surface on the left side of
In the single row angular contact ball bearing assembly according to a nineteenth preferred embodiment of the present invention shown in
As is the case with the single row angular contact ball bearing assembly according to a twentieth preferred embodiment of the present invention, the sealing members 6 and 6 shown in
According to this double row angular contact ball bearing assembly, since the recessed areas 16 as the grease scraping suppressing section is provided in each of the snap cages 5 and the two cages 5 and 5 are so arranged with their pocket surfaces opposed to each other, the grease leakage from the cage rear surface is suppressed. Accordingly, the grease deposition onto the outer diametric portion 2D of the inner ring 2 can be avoided. Therefore, the grease can be prevented from depositing in the seal groove 10 of the inner ring 2 and there is no need to change the design and the shape of the seal groove 10 and also to secure a space for installation of a slinger. Accordingly, the manufacturing cost can be reduced with the number of component parts reduced to a value smaller than those in the previously described Patent Documents.
In addition, when the suction phenomenon occurs in the sealing member 6, as shown in
As shown in
For this reason, the suction phenomenon can be avoided with the balance in pressure between the bearing inside and outside instantly maintained uniformly. The air passage Kta necessary to maintain this pressure balance is immediately closed if the balance in pressure between the bearing inside and outside is uniform, that is, no pressure difference is developed, and the sealing lip SL assumes a normal condition as shown in
In the double row angular contact ball bearing assembly, because of the unique shape of each of the cages, grease deposition on the inner ring outer diametric portion 2D is suppressed and the grease leakage from the cage back face side, that is, the counter-pocket side can be suppressed. Also, by the use of the sealing members 6 of the type described hereinbefore, not only can the leakage of the grease within the bearing assembly be avoided, but also intrusion of foreign matters from the bearing outside can be minimized.
A twenty second preferred embodiment of the present invention will now be described with particular reference to
The embodiment in this case differs from the previously described eighteenth embodiment in that as shown in
Due to the temperature change during the transportation of the angular contact ball bearing assembly, generation of a frictional heat caused by the rotation of the angular contact ball assembly and/or cooling the bearing assembly, the pressure difference is developed between the inside and the outside of the bearing assembly and, hence, when the sealing lip SL is urged inwardly, the projection Tj provided in the primary sealing lip Lc is brought into contact with the inner side face 10b of the seal groove as best shown in
In this condition, since an air passage Ktb communicating the bearing inside and the bearing outside is formed by the projection Tj, the difference in pressure between the bearing inside and the bearing outside is removed and a suction phenomenon of the bearing assembly can therefore be avoided. In addition, since the projection Tj protruding along the tip portion of the primary sealing lip Lc over the entire circumference is held in contact with the inner side face 10b of the seal groove 10, the sealing characteristic can be secured. If the projection Tj is collapsed as a result of its contact with the inner side face 10b of the seal groove 10 because of the large pressure difference between the bearing inside and the bearing outside and/or such pressure difference between the bearing inside and the bearing outside is very small, the suction phenomenon, in which the projection Tj and the tip portion of the primary sealing lip Lc are held in contact with the inner side face 10b of the seal groove 10, occurs as shown in
Because of the difference in contact pressure, the sliding resistance of the tip portion of the projection Tj becomes higher than that of the tip portion of the primary sealing lip Lc and, when under this sucked condition the bearing assembly is rotated, the projection Tj maintains the condition, in which it is in contact with the inner side face 10b of the seal groove 10 as shown in
The following summarizes the various preferred embodiments of the present invention which have been shown in and described with reference to
The ball bearing assembly, which forms a basic construction in each of the following modes, is of a structure including the cage of the present invention, a plurality of balls retained by this cage and interposed between the inner and outer rings, and sealing members provided in the outer ring or the inner ring for sealing the bearing space, in which one of the sealing members has one of peripheral edge portions, which is slidingly engaged in a seal groove formed in one end of one of raceways, and the other of the peripheral edge portions fixed to the other of the raceways, and
in which a peripheral edge of the sealing member slidingly engaged with the seal groove is rendered to be a sealing lip and, at the same time, this sealing lip has an inner face provided with a projection, the projection being displaceable between a first condition, in which when as a result of development of the pressure difference occurring in the bearing inside and the bearing outside that are divided by the sealing member, the sealing lip is urged inwardly, contacts an inner side face of the seal groove and, as a result of this contact of the projection, the sealing lip in the vicinity of the contact is partially elastically deformed to form an air passage that communicate between the bearing inside and the bearing outside, and a second condition, in which in the absence of the pressure difference referred to above, the projection is held in a non-contact with the inner side face of the seal groove.
The ball bearing assembly according to the above described basic construction is a double angular contact ball bearing assembly, which includes an outer ring having an inner periphery formed with double rows of raceway surface, an inner ring having an outer periphery formed with double rows of raceway surface that are opposed to the above mentioned raceway surfaces, double rows of balls interposed between the raceway surfaces in the inner ring and the raceway surfaces in the outer ring, a cage provided in the outer ring or the inner ring and employed for each of the rows of the balls for retaining the balls of the respective row, and opposite sealing members for closing an bearing space delimited between the inner ring and outer ring, in which there are provided the sealing members and two snap cages having respective pocket surfaces arranged so as to oppose to each other.
According to this construction, in the sealing members, if the suction phenomenon occurs, the sealing lip is urged inwardly, but simultaneously with the sealing lip being so urged, the projection in the inner face of the sealing lip is brought into contact with the inner side face of the seal groove. At this time, due to the presence of the projection the sealing lip in the vicinity of the position with the seal groove inner side face is partially elastically deformed relative to the other portion thereof. The primary sealing lip in the vicinity of the position of contact of the projection is incapable of contacting the inner side face of the seal groove and, due to the non-contact thereof, the air passage communicating between the bearing inside and the bearing outside is formed.
In the double row angular contact ball bearing assembly, because of the cage of the shape discussed above, deposition of the grease on the inner ring outer diametric portion is suppressed and the grease leakage from the cage back face side, that is, the counter-pocket side can be suppressed. Also, the use of the sealing members of the kind discussed above, not only can the grease leakage from inside of the bearing assembly be avoided, but also intrusion of foreign matters from the bearing outside is minimized to achieve a low torque.
In the above described basic construction, the projection may be formed a predetermined distance on the inner face of the sealing lip along the slidable tip portion thereof. When the suction phenomenon occurs, the projection referred to above is urged against the inner side face of the seal groove and, at the same time, the sealing lip in the vicinity of the projection is elastically deformed. For this reason, the slidable tip portion of the sealing lip and the inner side face of the seal groove separate from each other and the air passage for communicating between the bearing inside and the bearing outside is formed around the projection.
In the above described construction, the projection referred to above may be formed in the inner face of the sealing lip so as to protrude along the slidable tip portion thereof over the entire circumference and a cutout groove may be provided in a direction traversing the projection. In such case, when the suction phenomenon occurs, the projection is urged against the inner side face of the seal groove and, at the same time, the seal lip in the vicinity of this projection is elastically deformed. For this reason, the slidable tip portion of the sealing lip and the inner side face of the seal groove separate from each other and as a result, the air passage for communicating between the bearing inside and the bearing outside is formed in this cutout groove in the projection.
A twenty third preferred embodiment of the present invention will be described in detail with reference to
In this angular contact ball bearing assembly, the use of the sealing member 6, as will be detailed later, and the cage 5 of the present invention makes it possible to achieve a low torque, a resistance to the grease leakage, dust proofing and space saving and, at the same time, a low cost. As shown in
The details of the sealing member 6 will now be described.
As shown in
The sealing member 6 is of a structure, in which a portion of the elastic member 8 in an inner peripheral portion thereof is formed with a thin constricted area 8b having a small wall thickness. The constricted area 8b is formed so as to extend in constricted form from a primary sealing lip Lm or a labyrinth lip Ln or the both including the boundary therebetween, as will be described later, towards an outer diametric side. A tip portion on the inner peripheral side of the constricted area 8b is provided with a sealing lip 6a. The sealing lip 6a includes the primary sealing lip Lm contacting the raceway side groove wall 10b of the seal groove 10 and the labyrinth lip Ln protruding above the shoulder portion 2b.
The primary sealing lip Lm has an inclined wall face Lma spreading outwardly while opposed to the raceway side groove wall 10b of the seal groove 10, an inner peripheral face Lmb positioned radially inwardly of the inclined wall face Lma and opposed to the bottom surface 10a of the seal groove 10 and a tip portion Lmc continuously straddling between the inclined wall face Lma and the inner peripheral face Lmb. As shown in
The labyrinth lip Ln confronts a region ranging from the shoulder portion 2b to the shoulder portion side groove wall 10c of the seal groove 10, forming a labyrinth seal Ls. As shown in
The labyrinth lip Ln is has its tip portion provided adjacent the shoulder portion side wall 10c of the seal groove 10. Accordingly, the distance of travel of the muddy water, sticking to the labyrinth lip Ln, along the inclined face Lna by the effect of the centrifugal force resulting from the rotation of the sealing member 6 decreases and, hence, the muddy water pooled within the seal groove 10 is apt to be discharged. A step Ds is provided between the inner peripheral surface Lmb of the primary sealing lip Lm and the inclined face Lna of the labyrinth lip Ln. This step Ds is so provided as to protrude towards the shoulder portion side groove wall 10c of the seal groove 10. Accordingly, the inner peripheral surface Lmb of the primary sealing lip Lm is so formed as to be continued to the inclined face Lna of the labyrinth lip Ln through the step Ds and, therefore, the muddy water pooled within the seal groove 10 is apt to be discharged to the bearing outside along the inclined face Lna of the labyrinth lip Ln by the effect of the centrifugal force resulting from the rotation of the sealing member 6.
Also, if the step Ds is so provided as to protrude, a constricted portion is formed between an outer peripheral edge of the inner peripheral surface Lmb of the primary sealing lip Lm and the shoulder portion side groove wall 10c of the seal groove 10. By this constricted portion, the sealability by the labyrinth seal Ls can be secured. Since another constricted portion is formed also between a hill portion Yd at the boundary between the seal groove 10 and the shoulder portion 2b and the inclined face Lna of the labyrinth lip Ln, the sealability by the labyrinth seal Ls cal be further secured.
As shown in
An example of enforcement of the twenty third embodiment is as follows. A foreign matter intrusion test was conducted, in which the angular contact ball bearing assembly equipped with the sealing member 6 was fitted to a rotary testing machine under the environment, in which foreign matter such as a mixture of water and mud scattered continually, and the amount of intrusion of the foreign matter into the bearing space when the contact height position 63 of the tip portion Lmc into the raceway side groove wall 10b of the seal groove 10 was varied was then investigated. The contact height position 63 was varied to −0.1 mm and −0.05 (Embodiments), which were lower than the upper end position of the shoulder portion side groove wall 10c in the radial direction, and to 0.0 mm, 0.05 mm and 0.1 mm (Comparative Examples), which were equal to or higher than the upper end position of the shoulder portion side wall 10c. The amount of intrusion of the foreign matter was determined by measuring the amount of the mass of the bearing assembly before and after the test. Test conditions were as follows:
Results of the foreign matter intrusion test are shown in
According to the angular contact ball bearing assembly 1 according to the twenty third embodiment of the present invention as hereinabove described, since the snap cage 5 is provided with the recessed areas 16, the amount of grease sticking to the balls and scraped therefrom by the inner diametric surface 5d of the cage 5 can be reduced. Accordingly, the grease deposition onto the outer diametric portion 2D of the inner ring 2 can be avoided. Therefore, deposition of the grease onto the seal groove 10 in the inner ring 2 can be avoided. There is no need to change the design and the shape of the seal groove 10 and, also, to secure a space for installation of a slinger or the like. Accordingly, the manufacturing cost can be reduced with the number of component parts reduced as compared with those in the previously described Patent Documents. In addition, in the sealing member 6, the tip portion Lmc of the sealing lip 6a can be brought into engagement with the raceway side groove wall 10b at a location lower than the upper end position of the shoulder portion side groove wall 10c, which is opposed to the raceway side groove wall 10b of the seal groove 10. Accordingly, muddy water being scattered will not directly contact the tip portion Lmc of the contact sealing lip 6a. Therefore, the tip portion of the sealing lip 6a can be stably engaged with the raceway side groove wall 10b to allow the sealing member 6 to exhibit a sufficient sealing characteristic.
The counterbore portion forming the inner ring outer diametric surface on the left side of
In the single row angular contact ball bearing assembly according to a twenty fourth preferred embodiment of the present invention shown in
As is the case with the single row angular contact ball bearing assembly according to a twenty fifth preferred embodiment of the present invention shown in
In this double row angular contact ball bearing assembly, the use of the sealing members 6 and the cages 5 make it possible to achieve the low torque, resistance to grease leakage, dust proofing and space saving simultaneously and at a low cost. As shown in
According to the double row angular contact ball bearing assembly according to the twenty sixth embodiment, since the recessed areas 16 as the grease scraping suppressing section is provided in each of the snap cages 5 and the two cages 5 and 5 are so arranged with their pocket surfaces opposed to each other, the grease leakage from the cage rear surface is suppressed. Accordingly, the grease deposition onto the outer diametric portion 2D of the inner ring 2 can be avoided. Therefore, the grease can be prevented from depositing in the seal groove 10 of the inner ring 2 and there is no need to change the design and the shape of the seal groove 10 and also to secure a space for installation of a slinger. Accordingly, the manufacturing cost can be reduced with the number of component parts reduced to a value smaller than those in the previously described Patent Documents.
In addition, in the sealing member 6, the tip portion Lmc of the sealing lip 6a can be brought into engagement with the raceway side groove wall 10b at a location lower than the upper end position of the shoulder portion side groove wall 10c, which is opposed to the raceway side groove wall 10b of the seal groove. Accordingly, muddy water being scattered will not directly contact the tip portion Lmc of the contact sealing lip 6a. Therefore, the tip portion of the sealing lip 6a can be stably engaged with the raceway side groove wall 10b to allow the sealing member 6 to exhibit a sufficient sealing characteristic.
In this double row angular contact ball bearing assembly, thanks to the unique shape of the previously described cages, deposition of the grease on the inner ring outer diametric portion 2D is avoided and the grease leakage from the cage back face side, that is, the counter-pocket side can be suppressed. Also, the use of the sealing members 6 of the type referred to above, the leakage of the grease within the bearing assembly can be avoided and the resistance to muddy water can be obtained. Therefore, since there is no increase the tightening force of the lip or the like, the low torque can be achieved.
The following summarizes modes of the various preferred embodiments of the present invention which have been shown in and described with reference to
The ball bearing assembly, which forms a basic construction in each of the following modes, is of a structure including the cage of the present invention, a plurality of balls retained by this cage and interposed between the inner and outer rings, and a sealing member provided in the outer ring or the inner ring for closing the bearing space between the inner and outer rings, one of opposite peripheral edge portions of the sealing member being held in sliding contact in a seal groove defined in one end of one raceway whereas the other of the peripheral edge portion is fixed to one end of the other raceway,
in which the peripheral edge of the sealing member slidingly engageable in the seal groove is rendered to be a sealing lip and an inner face of this sealing lip is formed with a projection, which projection is operable to contact an inner side face of the seal groove in the event that the difference in pressure between a bearing inside and a bearing outside that are divided by the sealing member occurs with the sealing lip consequently urged inwardly, the projection being displaceable between a first condition, in which as a result of this contact of the projection, the sealing lip in the vicinity of the contact is partially elastically deformed to form an air passage that communicate between the bearing inside and the bearing outside with each other, and a second condition, in which in the absence of the pressure difference referred to above, the projection is held in a non-contact with the inner side face of the seal groove.
The ball bearing assembly of the basic construction described above is a double row angular contact ball bearing assembly of a structure, in which respective pocket surfaces of the two cages are so arranged as to oppose to each other.
According to the above construction, since the primary sealing lip and the labyrinth lip are provided in the inner peripheral portion of the sealing member, the primary sealing lip is provided with an inner peripheral surface opposed to the seal groove, and the labyrinth lip has an inner periphery formed with an inclined face, the tip portion of the primary sealing lip can be brought into contact with the raceway side groove wall of the seal groove at a contact position lower than the upper end position of the shoulder side groove wall opposed to the raceway side groove wall of the seal groove.
In the double row angular contact ball bearing assembly, thanks to the unique shape of the previously described cage, deposition of the grease on the inner ring outer diametric portion is suppressed and the grease leakage from the cage back face side, that is, the counter-pocket side can be suppressed. Also, the use of the sealing member of the kind described above makes it possible to avoid the grease leakage within the bearing assembly and also to secure the resistance to muddy water.
In the basic construction described above, the angle of inclination of the inclined face of the labyrinth lip referred to above may be so set as to be within the range of 10 to 40° relative to the outer peripheral surface of the shoulder portion. Once this angle of inclination is set, muddy water pooled within the seal groove moves axially outwardly along the inclined face of the labyrinth lip under the influence of the centrifugal force developed as a result of rotation of the sealing member and is subsequently easily discharged to the bearing outside.
If the angle of inclination of the inclined face of the labyrinth lip is smaller than the lower limit of 10°, the centrifugal force resulting from the rotation of the sealing member becomes small and, therefore, the muddy water will be hardly discharged. On the other hand, if the angle of inclination is greater than the upper limit of 40°, the gap between the outer peripheral surface of the shoulder portion and the inclined face of the labyrinth seal expands, resulting in reduction in sealability exhibited by the labyrinth seal.
In the basic construction described above, the inclined face of the labyrinth lip may be provided at its axially inner end portion with a step protruding towards the shoulder portion side groove wall of the seal groove and be continued to the inner peripheral surface of the primary sealing lip through this step. Since the step protrudes towards the shoulder portion side groove wall of the seal groove, a constricted portion is formed in the labyrinth seal formed by the labyrinth lip and the sealing characteristic brought about by this labyrinth seal can be secured.
In the basic construction described above, the sealing member may be rendered to be of a type in which an elastic body is reinforced by a core metal. In such case, the rigidity of the sealing member is increased so that it can be stably held in contact with the inner side wall of the seal groove without allowing the tip portion of the sealing lip to be undesirably deformed elastically.
In the basic construction described above, the elastic body of the sealing member may be a hydrogen added nitryl rubber or ester resistant acrylic rubber. Since the hydrogen added nitryl rubber is excellent in heat resistance as compared with nitryl rubber generally used as a sealing member and, since it has no problem in respect of the chemical resistance thereof, not only can stabilized characteristics be maintained, but also it can be used at higher temperature, particularly where the hydrogen added nitryl rubber is employed as the elastic body of the sealing member.
The ester resistant acrylic rubber is excellent in heat resistance as compared with the nitryl rubber as is the case with the hydrogen added nitryl rubber and the chemical resistance against chemicals such as, for example, an ester oil of the acrylic rubber and a compressor oil used in an air conditioner is increased/For this reason, particularly where the ester resistant acrylic rubber is employed as the elastic body of the sealing member, not only can stabilized characteristics be maintained, but also it can be used at higher temperature.
A twenty seventh preferred embodiment of the present invention will now be described with particular reference to
The sealing member 6 includes an annular core metal 7 and a rubber member 8 integrated with this core metal 7 and has its outer peripheral portion mounted on a seal anchoring groove 9 defined in an inner peripheral surface of the outer ring 3. The rubber member 8 is made of a synthetic rubber and the core metal 7 is rendered to be in the form of a product of a steel plate. The inner ring 2 is formed with a seal groove 10 at a location corresponding to an inner diametric portion of each of the sealing members 6 and a labyrinth seal gap 62 is formed between an inner diametric side end of the sealing member 6 and the seal groove 10 in the inner ring 2 The seal fitting groove 9 and the seal groove 10 are finished by a turning process.
As shown in
An inner diametric portion of the metal-coreless rubber portion 8a is formed to have two sealing lips, that is, a center sealing lip 8ad and a dust sealing lip 8ae extending towards the inner diametric side and the bearing outside, respectively. The dust sealing lip 8ae extends towards the bearing outside with the center sealing lip 8ad serving as a base end. The center sealing lip 8ad extends towards the bearing inside and keeps in a non-contact relation with the seal groove inner side wall 10b. Thus, with the center sealing lip 8ad extending towards the bearing inside, the axial position of the center of gravity of the metal-coreless rubber portion 8a is offset towards the bearing inside from the center of the section of the constricted area 8ab, more specifically from the center of the section of a groove bottom portion of the constricted area 8ab.
The labyrinth seal gap δ2 defined between the inner diametric end side of the sealing member 6 and the outer diametric surface of the inner ring 2 is formed, at a plurality of locations arranged in inner and outer directions, with respective constricted areas δ2a to δ2c of predetermined gap dimensions according to respective shapes of sealing lips 8ad and 8ae formed in the inner diametric portion of the metal-coreless rubber portion 8a. More specifically, the first constricted area δ2a is formed between the dust sealing lip 8ae and the outer diametric surface of the inner ring 2; the second constricted area δ2b is formed between the center sealing lip 8ad and the seal groove outer side wall 10c of the inner ring; and the third constricted area δ2c is formed between the center sealing lip 8ad and the seal groove inner side wall 10b of the inner ring 2. The outermost constricted area δ2a is so formed as to be narrower than the other constricted areas δ2b and δ2c. Accordingly, the labyrinth seal gap δ2 has three large and narrow varying portions, each comprises of a set of narrow and wide locations.
At two locations arranged in a radial direction, a side face on the inner side of the sealing member 6 is formed with grease reservoir 6A and 6B each in the form of an annular groove. Of those grease reservoirs 6A and 6B, the grease reservoir 6A on the outer diametric side has an outer diametric dimension, which is so selected as to be smaller than the inner diametric dimension of the outer ring 3. Since the sectional shape of the inner diametric side end of the sealing member 6 is so designed that the constricted areas δ2a to δ2c each being of a gap dimension are formed, and arranged in the inner and outer direction, in the labyrinth seal gap δ2 formed between the sealing member inner diametric end and the outer diametric surface of the inner ring 2, a plurality of (for example, three in the illustrated instance,) three large and narrow varying portions, each comprises of a set of narrow and wide locations, are formed in the labyrinth seal gap δ2. Since as described above the labyrinth seal gap δ2 varies wide and narrow, the capability of avoiding the grease leakage from the labyrinth seal gap δ2 can be enhanced. Accordingly, contamination of the surrounding due to the grease leakage can be avoided.
Also, since the axial position of the center of gravity of the metal-coreless rubber portion 8a in the sealing member 6 is offset towards the bearing inside from the center of the section of the constricted area 8ab, waggling of an inner diametric portion tip portion of the sealing member 6 towards the bearing outside during, for example, the rotation of the outer ring can be suppressed. For this reason, the pumping effect, which arises when due to the waggling the gap δ2 between the sealing member 6 inner diametric end and the seal groove 10, can be reduced to thereby suppress promotion of the grease leakage which would result from the pumping effect.
With respect to the side face on the inner side of the sealing member 6, since the grease reservoirs 6A and 6B each in the form of an annular groove are employed and arranged in the radial direction and since the outer diametric dimension of the grease reservoir 6A on the outer diametric side is so chosen to be smaller than the inner diametric dimension of the outer ring 3, the grease within the grease reservoirs 6A and 6B can be supplied gradually towards the raceway surface 3a by the effect of the centrifugal force developed during the outer ring rotation. For this reason, it is possible to cause the grease within the grease reservoirs 6A and 6B to participate in lubrication of the raceway surfaces 2a and 3a.
Hereinafter, the rotary encoder RE will be described.
The rotary encoder RE includes a magnetic encoder EC and sensors E4 and E5. Of them, the magnetic encoder EC is provided with an inner ring side core metal E1. At the end opposite to the side where the sealing member 6 is provided, the annular inner ring side core metal E1 is fixedly mounted on the outer diametric surface of the inner ring 2. An outer ring side core metal E2 is fixed to the inner diametric surface of the outer ring 3 The inner ring side core metal E1 and the outer ring side core metal E2 are opposed to each other in the radial direction. The inner ring side core metal E1 is provided with an L-sectioned inner ring side mounting portion E1b, which is bent at an outer end of an annular inner ring side fixing portion E1a in a direction in which diametric expansion takes place, and a magnetic encoder body is fixedly mounted on an outer diametric surface of this inner ring side mounting portion E1b. This magnetic encoder body is of a type having an array of magnetic poles of a predetermined width magnetized alternately at a predetermined pitch in a direction circumferentially thereof over the entire circumference thereof.
The outer ring side core metal E2 is of a type provided with an outer ring side mounting portion E2b of an L-sectioned configuration at the outer end of the annular outer ring side anchoring portion E2a, and this outer ring side mounting portion E2b protrudes in the axial direction a distance greater than the inner ring side mounting portion E1b. Also, the outer ring side anchoring portion E2a has an inner diametric surface formed with a sealing portion E2c protruding over the entire circumference in a direction towards the inner ring side anchoring portion E1a. In the outer ring side core metal E2, a sensor holder Hd is mounted on an inner surface of the outer ring side mounting portion E2b of the L-sectioned configuration and an electric circuit substrate E3 and others are integrally fixed in a portion of this sensor holder Hd. A portion on a small diametric side of the sensor holder Hd has the electric circuit substrate E3 embedded therein over a required range in the circumferential direction. This electric circuit substrate E3 has an inner surface an A phase sensor E4 in the form of, for example, a Hall IC and a B phase sensor E5 provided thereon, having been spaced a predetermined space in the circumferential direction, so as to protrude inwardly therefrom. Each of the sensors E4 and E5 are exposed at an inner diametric surface of a large diameter in the sensor holder Hd and confronts the magnetic poles of the magnetic encoder EC.
In the bearing assembly for the rotary encoder equipped motor according to this embodiment, any of the cages 5 according to the respective embodiments of the present invention can be employed. Accordingly, not only can the grease leakage towards the inner ring outer diametric portion be avoided and, hence, the flow of the grease towards the sensors E4 and E5 of the rotary encoder RE or the seal groove 10 in the inner ring 2 can be avoided to thereby prevent the grease from leaking from the bearing assembly for the rotary encoder equipped motor.
Also, since the provision of the cage 5 of the type hereinbefore described the grease leakage can be prevented, there is no need to change the design and the shape of the seal groove 10 of the inner ring 2 and, also, there is no need to provide a slinger or the like in the axial direction of the bearing assembly. Accordingly, space saving can be accomplished with no need to increase the number of component parts. Therefore, the grease deposition on the sensors E4 and E5 of the rotary encoder RE is also prevented and it is possible to accurate detect the rotating condition. In addition, since the grease leakage is prevented, the sealing member 6 comprised of the non-contact seal can be adopted and, hence, a low torque characteristic can be accomplished. Even when the sealing member 6 comprises of the non-contact seal is adopted, the use of the cage of the structure hereinbefore described makes it possible to increase the dust proofing characteristic.
The following applied examples are contemplated, in which the structural feature of the use of the “recessed areas formed in the inner face of each of the pockets so as to extend from the pocket open edge on the cage inner diametric side towards the cage outer diametric side” is not employed.
The cage for the ball bearing assembly according to the first applied example is a snap cage including an annular body formed in one side face of the annular body with partially opened pockets at a plurality of circumferential locations of the annular body, and a pair of pawls provided on the open side of each the pockets so as to protrude axially and opposed to each other in the circumferential direction, in which the distance between respective tip portions of the pair of the pawls of each of the pockets on the cage outer diametric side is chosen to be smaller than the distance between the tip portions on the cage inner diametric side.
According to the first applied example described above, since the distance between respective tip portions of the pair of the pawls of each of the pockets on the cage outer diametric side is chosen to be smaller than the distance between the tip portions on the cage inner diametric side, the grease adhering to the balls will not be permitted to approach the outer diametric portion of the inner ring from the outer ring side and even the grease from the inner ring side can be scraped by the cage outer diametric side of the pawls distant from the outer diametric portion of the inner ring and, as a result, the grease leakage from the ball bearing assembly can be avoided.
The cage for the ball bearing assembly according to the second applied example is a snap cage including an annular body formed in one side face of the annular body with partially opened pockets at a plurality of circumferential locations of the annular body, and a pair of pawls provided on the open side of each the pockets so as to protrude axially and opposed to each other in the circumferential direction, in which a space between the respective tip portions on the cage inner diametric side of the pair of the pawls of each of the pocket is opened and the respective tip portion on the cage outer diametric side are connected together.
According to the second applied example, since the space between the respective tip portions on the cage inner diametric side of the pair of the pawls of each of the pocket is opened and the respective tip portion on the cage outer diametric side are connected together, the grease adhering to the balls will not be permitted to approach the outer diametric portion of the inner ring from the outer ring side and even the grease from the inner ring side can be scraped by the cage outer diametric side of the pawls distant from the outer diametric portion of the inner ring and, as a result, the grease leakage from the ball bearing assembly can be avoided.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings which are used only for the purpose of illustration, those skilled in the art will readily conceive numerous changes and ‘ modifications within the framework of obviousness upon the reading of the specification herein presented of the present invention. Accordingly, such changes and modifications are, unless they depart from the scope of the present invention as delivered from the claims annexed hereto, to be construed as included therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-072930 | Mar 2008 | JP | national |
| 2008-074964 | Mar 2008 | JP | national |
| 2008-181163 | Jul 2008 | JP | national |
| 2008-191164 | Jul 2008 | JP | national |
| 2008-212744 | Aug 2008 | JP | national |
| 2008-212745 | Aug 2008 | JP | national |
| 2008-212746 | Aug 2008 | JP | national |
| 2009-037447 | Feb 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/001236 | 3/19/2009 | WO | 00 | 9/17/2010 |
