The present invention relates to a sealing structure for a fitting portion, for example, to a sealing structure for a fitting portion of a slinger constituting an oil seal and a rotary side member of a bearing device.
For example, in an automotive bearing device, a slinger of which section is in the shape of the letter “L”, having a cylindrical part and a flange part extending from one end of the cylindrical part, is fitted to a rotary side member (an inner ring member, a drive shaft, and the like) from the other end of the cylindrical part in such a manner that the cylindrical part is fitted; and an oil seal (a bearing seal) is incorporated, the oil seal being constructed in such a manner that a seal lip of a seal lip member fitted to the stationary side member (an outer ring member) via a core member elastically contacts the surface of the cylindrical part opposite to the fitting portion and one surface of the extending flange part. In such a case, ingress of dirty water and the like into the bearing is prevented by elastic contact of the seal lip to the slinger, or leakage of lubricant agent filled in the bearing is prevented. However, the fitting portion of the slinger and the rotary side member and the fitting portion of the core member holding the seal lip member and the stationary side member adopt metal-to-metal fitting, so that dirty water may enter the bearing because of processing accuracy of metal members and minute scratch on the surface. When dirty water enters the bearing, the orbit surface of the bearing and the surface of a rolling element are scratched and the bearing performance is remarkably deteriorated. Patent Literatures 1 to 4 disclose that a seal member is provided for the slinger or a rotary shaft for preventing ingress of dirty water and the like through the fitting portion of the slinger, a drive shaft (the rotary shaft) or an inner ring.
PTL 1 relates to an oil seal provided for a rotary shaft projecting a housing and discloses a packing, corresponding to the above-mentioned seal member, for sealing a fitting gap between a slinger and a rotary shaft. However, PTL 1 does not show clearly how the packing is mounted to the slinger or the rotary shaft. It is understood that the packing is mounted on the forward part in the fitting direction of the slinger to the rotary shaft because a seal ring having a seal lip is positioned on the atmospheric side. Therefore, when the slinger is fitted to the rotary shaft, it is forecasted that the fitting resistance increases by the packing and fitting is not executed smoothly or a part of the packing enters a compression-fitting portion of the slinger and the rotary shaft to be broken.
PTL 2 relates to a seal for a wheel bearing device and discloses a shielding lip, corresponding to the above-mentioned seal member, provided for a rising plate part (flange part) of a slinger. This shielding lip is made of an elastic member such as rubber and so on and is integrally adhered by vulcanizing to the rising plate part. The shielding lip elastically contacts the end surface of the inner ring so as to prevent rain water and so on from entering the bearing or prevent rust at an exposed part of the inner ring from proceeding to a magnetic encoder attached to the slinger. It is understood that the slinger is provided in a molding and the shielding lip is formed by vulcanization molding in which adhesive agent is applied to a predetermined part and rubber and the like are injected thereon because the shielding lip is integrated to the slinger by vulcanization adhesion. In case of vulcanization molding, the device becomes large, an application procedure of adhesive agent is required so that molding procedures become complex, and process cost increases. In addition, the shielding lip inevitably has a certain thickness and a certain size, so that it may be broken by the shear stress at the time of fitting when being interposed in the fitting portion between the slinger and the inner ring, thereby its sealing function cannot be adequately exerted.
PTL 3 relates to a bearing seal for a wheel bearing device and discloses an O-ring, corresponding to the above-mentioned seal member, which is interposed between a cylindrical part of a core member fixedly holding a cylindrical part of a slinger and a seal lip, and inner ring (rotary side member) or an outer ring (stationary side member). In such a case, an O-ring is easily obtained as a seal packing in the market and the sealing structure of the fitting portion can be easily constituted; however, a circumferential groove for fitting is required to be provided on the inner ring and the outer ring because the O-ring is easily removed from the fitting portion. Even when the O-ring is fitted in the circumferential groove, if it is mounted to a part to which fitting pressure is largely operated, it may cause buckle by the shear stress.
PTL 4 relates to a sealing device for a wheel bearing (a bearing seal) and discloses a second seal layer, corresponding to the above-mentioned seal member, fowled on a corner part from a cylindrical part to a flange part of a slinger for sealing between a cylindrical part of a second seal annular body (slinger) and an outer circumference of an inner ring. Although the second seal layer is disclosed to be formed by baking an elastic body such as rubber and the like to the slinger, a specific method is not described. A stepped part is formed at a formative part of the second seal layer in the cylindrical part of the slinger so as to accommodate the second seal layer therein. Therefore, it is understood that the second seal layer interposed between the cylindrical part of the slinger and the inner ring does not become a compressed state and it is not clear that how much sealing performance is achieved between the slinger and the inner ring.
The present invention is proposed in view of the above-mentioned problems and has an object to provide a sealing structure for a fitting portion in which the structure is simplified, the sealing performance is superior, a sealing part hardly breaks at fitting, and the sealing performance is kept for a long time.
According to the present invention, a sealing structure for a fitting portion where a cylindrical part of an annular member is concentrically fitted to a cylindrical member to be fitted is characterized in that an elastic annular seal layer is integrally formed on a backward end part of the annular member or the cylindrical member in fitting direction by applying elastomeric agent to the backward end part and hardening it; and that the elastic annular seal layer is formed such that it has layer thickness of 5 μm to 1 mm and is interposed in a compressed state between the annular member and the cylindrical member when the annular member is fitted to the cylindrical member.
According to the present invention, elastomeric agent with viscosity equal to or over 20 Pa·S in application process can be used as the elastomeric agent for forming the elastic annular seal layer. The annular seal layer can have a convex sectional shape, a plane chamfered sectional shape, a concave sectional shape, or a stepped cut sectional shape in its formative part.
Furthermore, according to the present invention, the annular member can be a slinger of a seal member and can comprise the cylindrical part and a flange part extending from one end of the cylindrical part, and an elastic contacting surface for a seal lip of the seal member can be formed at a surface of the annular member opposite to the fitting portion and at one surface of the flange part extending therefrom. In this case, the annular seal layer can be formed on the backward end part of the annular member in the fitting direction and a surface area which the seal lip does not contact can be formed at a surface opposite to an area where the annular seal layer is formed.
According to the sealing structure for a fitting portion of the present invention, the cylindrical part of the annular member is concentrically fitted to the cylindrical member to be fitted. At the backward end part of the annular member in the fitting direction when the annular member is fitted, the elastic annular seal layer formed by applying and hardening the elastomeric agent is integrally formed, the annular seal layer is interposed in a compressed state between the annular member and the cylindrical member in such a fitting state, thereby the fitting portion of the annular member and the cylindrical member is sealed. In particular, when the annular member and the cylindrical member are made of metal, superior sealing performance can be exerted without being adversely affected by processing accuracy and minute scratch on the fitting surface.
At the backward end part of the annular member or the cylindrical member in the fitting direction, the elastic annular seal layer formed by applying and hardening the elastomeric agent is integrally formed, so that the shear stress applied to the elastic annular seal layer between the fitting members at the time of fitting becomes small and fracture of the elastic annular seal layer at the time of fitting is reduced. In addition, the annular seal layer is designed to have layer thickness of 5 μm to 1 mm, so that preferable sealing performance can be obtained and there is no fear of such fracture at the time of fitting. When the layer thickness is less than 5 μm, the sealing performance tends to be deteriorated by being affected by processing accuracy and minute scratch on the surface of the fitting members. When the layer thickness is over 1 mm, the shear stress at the time of fitting strongly operates and fracture is easily caused.
Because the annular seal layer is formed by applying and hardening the elastomeric agent, the layer thickness can be easily made thin as mentioned above. A large-scale molding device and application of adhesive agent, which are required for adhesion by vulcanizing, are not required, therefore, an annular member can be obtained easily without increasing process cost. When the viscosity of the elastomeric agent for forming the elastic annular seal layer is 20 Pa·S or over at the time of application, the elastic annular seal layer can be accurately formed in desired shape. When the elastomeric agent is applied and hardened by a dispenser method and the viscosity of the elastomeric agent is less than 20 Pa·S, the elastomeric agent may flow (drop) before being hardened, or the elastomeric agent may cause sticky-string phenomenon when the application is stopped and a nozzle is removed from an applied part, as a result the hardened elastic annular seal layer sometimes does not become a desired shape.
The sectional shape of the part where the annular seal layer is formed can be convex, planely chamfered, concave or in the shape of step by cutting. Because of such configuration, the application area on the annular seal layer is effectively secured. When it is concave or in the shape of step by cutting, the application stability of the annular seal layer increases. Even if the layer thickness increases, the shear stress is not strongly operated and fear of fracture of the annular seal layer can be more reduced at the time of fitting. In particular, when the annular seal layer is in the shape of step by cutting, relief of the annular seal layer at the time of fitting is secured and fracture of the annular seal layer is reduced.
The annular member can be the slinger comprising the cylindrical part and the flange part extending from one end of the cylindrical part and the surface of the annular member opposite to the fitting portion and one side of the flange part extending therefrom can be formed as the elastic contacting surface of the seal lip constituting the seal member. In such an embodiment, for example, when the slinger is fitted to the rotary side member and the core member integrally holding the seal lip is fitted to the stationary side member, an oil sealing structure for preventing leakage of oil can be constructed. In addition, when the annular seal layer is formed at the backward end part of the annular member, namely a slinger, in the fitting direction, a preferable sealing state can be kept at the fitting portion with the rotary side member and ingress of dirty water and the like to the fitting portion can be accurately prevented. In such a case, the surface opposite to the part, where the annular seal layer is provided, of the annular member is formed as a surface area which the seal lip does not elastically contact, release of friction heat by elastic sliding contact of the seal lip is not hindered and deterioration of the seal lip by the friction heat can be controlled.
a and
a and
a is an enlarged view of “C” in
a,
b and
a corresponds to the enlarged view in
Embodiments of the present invention are explained referring to the attached drawings.
The bearing seals 10, 11 as mentioned above are designed to be a pack seal type and their basic structures are similar, However, a magnetic encoder 12 is provided at the outer end surface of the automotive body side bearing seal 11 (surface on the automotive body side) and the magnetic encoder 12 and a magnetic sensor 13 correspondingly provided on the body side constitute a rotation detection device of a tire wheel. The magnetic encoder 12 is a multi-polar magnetic ring constituted of a rubber ring which is molded by mixing magnetic powder in rubber material and S-poles and N-poles are alternately provided along the circumferential direction so as to be magnetized.
The structure of the bearing seal 11 is explained referring to
An annular seal layer 14d formed by applying and hardening elastomeric agent is provided at an external corner part 14c of one end of the cylindrical part 14a of the slinger 14 and the extending base part of the outward flange part 14b extending from the one end of the cylindrical part 14a as shown in
While the slinger 14 and the inner ring member 6 are fitted, a part of the annular seal layer 14d is interposed in a compressed state in the fitting portion at the backward end part in the fitting direction, so that the space between both fitting surfaces in the fitting portion is sealed and outside dirty water and the like are prevented from entering the space. Accordingly, even if there is processing tolerance or the fitting surfaces have minute scratch when metal members are fitted, ingress of dirty water and the like into the fitting portion is prevented by the annular seal layer 14d, thereby reducing rust of the fitting surfaces. In addition, when the slinger 14 and the core member 15 are combined as shown in the figure, the seal lips 16a, 16b, 16c of the elastic seal lip member 16 integrally fixed to the core member 15 elastically contact the surface on the bearing space side of the slinger 14, namely the outer circumference of the cylindrical part 14a and the surface of the flange part 14b opposite to the encoder 12. When the drive shaft 3 axially rotates, the seal lips 16a, 16b, 16c slidably and relatively contact the elastic contacting surfaces. Therefore, dirty water is prevented from entering the bearing space 1a by interaction effects of dirty water prevention function of the annular seal layer 14d and the elastically contacting seal function of the seal lips 16a, 16b, 16c to the slinger 14, thereby achieving long life of the bearing device 1. The surface of the slinger 14 opposite to the formative part of the annular seal layer 14d (surface on the bearing space 1a side) is an area which any one of the seal lips 16a, 16b, 16c does not elastically contact, so that deterioration of seal lip is not advanced without accumulating friction heat caused by elastic contact.
The annular seal layer 14d is formed by applying the elastomeric agent and hardening it. Two-component-hardening type silicone elastomer, one-component-hardenable type silicone elastomer, or one-component-hardening type phlorosilicone elastomer are used as the elastomeric agent. These elastomeric agent is liquid and is discharged and applied to a predetermined portion, namely the external corner 14c, by a dispenser and the like while the slinger 14 as a work axially rotates, and is hardened according to predetermined hardening conditions, thereby obtaining the annular seal layer 14d. The two-component-hardening type silicone elastomer can be hardened at room temperature in a short time and is superior in operation performance. The one-component-hardening type silicone is required to be hardened by heat or by moisture, so that the operation performance is inferior than the two-component-hardening type silicone elastomer; however, the usable time is long and the one-component-hardening type silicone is advantageous in storage. In addition, the one-component-hardening type phlorosilicone elastomer is required to be hardened by heat or moisture, is inferior in the operation performance to the two-component-hardening the silicone elastomer and is expensive; however, the usable time is long and the one-component-hardening type phlorosilicone elastomer is advantageous in storage, in addition it is superior in heat resistance and oil resistance.
In addition to the above-mentioned elastomeric agent, any component which can form the elastic seal layer 14d by applying and hardening can be appropriately and selectively applied considering the availability such as property and so on. The above-mentioned elastomeric agent is appropriately and selectively applied considering the application operationability, performance, cost, and so on generally. More specifically, the preferable hardened elastomer has; the hardness of ShoreA: 20 to 90 (preferably 20 to 70), the tensile strength of 0.3 MPa or over, and stretch of 100% or over. In the present invention, elastomeric agent is selected in view of performance such as heat resistance, low-temperature resistance, water resistance, ozone resistance, chemical resistance, thermal shock resistance, and so on.
When the above-mentioned elastomeric agent is applied and hardened, the layer thickness (film thickness), the size (width) and the like of the elastic seal layer 14d are controlled by changing the nozzle diameter and discharge amount of the dispenser and the rotary speed of the slinger 14. When the elastomeric agent is baked and hardened by heating, the deformation shape is changed by drip of applied elastomeric agent by changing the time from application to baking of the agent, so that the layer thickness “d”, the size and the like of the elastic seal layer 14d are controlled by changing the time.
The metal slinger 14 and the inner ring member 6 which were fitted as shown in
The same slinger 14 and the inner ring member 6 as the experimental example were prepared, the slinger 14 without having the annular seal layer 14d was fitted to the inner ring 6 without having scratch on the outer circumference, and to the inner ring member 6 with the same scratch as in the experimental example, and the same air-leak experiment was executed. In case of the inner ring member 6 without scratch, air leak was shown around the inner pressure of 0.3 MPa, and in case of one with scratch, air leak was shown at the inner pressure of 0.1 MPa or less.
As shown in the results of Experimental Example and Comparison Example, it is understood that the sealing performance in the fitting portion between the slinger 14 and the inner ring member 6 is remarkably superior when the annular seal layer 14d is formed. It is found by repeating the air leak experiments that the layer thickness “d” is preferably 6 μm to 1 mm. When it is less than 5 μm, the sealing performance tends to be deteriorated by the effect of the processing accuracy of the fitting member and minute scratch on the surface thereof. When it exceeds 1 mm, the shear stress at the time of fitting strongly acts and fracture was easily caused.
Elastomeric agents with different viscosity were prepared, discharged and applied on an experimental piece by a dispenser, and the evaluation test was executed on the moldability of the annular seal layer in the process of hardening.
a,
b,
a and
The sectional shape of the external corner part 14c where the annular seal layer 14d is formed is planely chamfered in the embodiment of
In the embodiment shown in
a is an enlarged view of “C” in
In
The annular seal layer 14d of predetermined layer thickness “d” is formed on the external corner part 14c constituting an extending base part of the flange part 14b of the slinger 14. A part of the annular seal layer 14d is interposed in a compressed state in the fitting portion between the protecting cover 17 and the slinger 14 when they are fitted. An annular seal layer 17d is formed by applying the elastomeric agent and hardening it as mentioned above at an external corner part 17c of one end of the cylindrical part 17a of the protective cover 17 and the extending base part of an outward flange part 17b extending from the one end. In such a case, the annular seal layer 17d is formed, the sectional shape is convex in the figure, and the annular seal layer 17d is formed on the external corner part 17c on the external corner part 17c so as to have a predetermined layer thickness “d”. The cylindrical part 17a is fitted to the outer circumference of the inner ring member 6 as the member to be fitted and a part of the annular seal layer 17d (two-dotted line) is interposed in the fitting portion thereof in a compressed state. Accordingly, the fitting portion of the inner ring member 6 and the protective cover 17 is sealed and dirty water and the like are prevented from entering the bearing space 1a through the fitting portion. The fitting portion of the protective over 17 and the slinger 14 is sealed by the annular seal layer 14d, so that dirty water and the like are also prevented from entering the bearing space 1a through the fitting portion.
The annular seal layers 14d, 17d in this embodiment can be formed like the embodiment in
The inner ring member 24 is fitted to the wheel hub 23 from the automotive body side, and removal prevention and pre-compression as a bearing are exerted by enlarging and caulking the automotive body side end part 23b of the wheel hub 23. For this purpose, the automotive body side end part of the outer ring 21 is opened, the cap member 27 is fitted and attached to the opening (inner circumference) 21a of the outer ring 21 after fitting and attaching the inner ring member 24, and ingress of dust and dirty water is prevented from entering the fitting portion of the outer ring 21 and the inner ring 25. The cap member 27 comprises a cylindrical part 27a fitted to the inner circumference 21a of the outer ring 21 and a cover plate part 27h which extends from one end of the cylindrical part 27a (the backward end part in the fitting direction along the outlined arrow) and closes the opening of the cylindrical part 27a. In the fitting relation of the cap member 27 and the outer ring 21, the former corresponds to the annular member of the present invention, and the latter corresponds to the member to be fitted in the present invention.
A ring 28 with an “L” shaped section for supporting the encoder is fitted to the outer circumference of the inner ring member 24 and the same magnetic encoder 12 as mentioned above is adhered and integrated to the automotive body side of the ring 28. The cap 27 is fitted to the outer ring 21 so as to cover the magnetic encoder 12. A magnetic sensor, not shown, is provided adjacent to the magnetic encoder 12 outside the cap 27 and a rotation detection device for wheels is constituted as mentioned above. The cap 27 has a cover function for protecting the magnetic encoder 12 and prevents damage of the magnetic encoder 12 by dust and so on.
On the external corner part 27c of the cap member 27 at the extending base part of one end of the cylindrical part 27a and the cover plate part 27b, an annular seal layer 27d is formed with predetermined layer thickness “d” by applying the elastomeric agent and hardening it as mentioned above. The annular seal layer 27d is formed on the external corner part 27c which has planely chamfered sectional shape in the figure. When the cap member 27 is fitted and attached to the opening 21a of the outer ring 21, a part of the annular seal layer 27d (two-dotted line) is interposed in a compressed state at the fitting portion thereof, thereby the fitting portion is sealed and ingress prevention function of dust and dirty water by the cap 27 is ensured.
a,
b and
The inside corner 21e and the outside corner 21f of the wheel side end surface 21d of the outer ring 21 are planely chamfered and are provided with annular seal layers 21g, 21h formed with predetermined layer thickness “d” by applying the elastomeric agent and hardening it as mentioned above. When the core member 29 of the bearing seal 26 is fitted to the outer ring 21 along the direction of the outlined arrow, the annular seal layers 21g, 21h are interposed in a compressed state between the core member 29 and the outer ring 21. Therefore, the fitting portion of the core member 29 and the outer ring 21 is sealed and dirty water and the like which have reached the outer circumference 21i of the outer ring 21 are prevented from entering the bearing space 20a through the fitting portion.
The bearing seal 26 in
The inside corner 21e and the outside corner 21f of the wheel side end surface 21d of the outer ring 21 are planely chamfered and are provided with the annular seal layers 21g, 21h formed with predetermined layer thickness “d” by applying the elastomeric agent and hardening it as mentioned above. When the core member 31 of the bearing seal 26 is fitted to the outer ring 21 along the direction of the outlined arrow, the annular seal layers 21g, 21h in a compressed state are interposed between the core member 31 and the outer ring 21. Therefore, the fitting portion of the core member 31 and the outer ring 21 is sealed and dirty water and the like which have reached the outer circumference 21i of the outer ring 21 is prevented from entering the bearing space 20a through the fitting portion.
The exterior seal 33 comprises a core member 34 fitted to the outer circumference 21i of the outer ring 21 along the direction of the outlined arrow, and a seal lip member 35 having a seal lip 35a which elastically contacts or is close to a hub flange of the wheel hub 23 and being integrally fixed to the core member 34. The core member 34 comprises a cylindrical part 34a fitted to the outer circumference 21i of the outer ring 21, and an inward flange part 34b extending from the backward end part of the cylindrical part 34a in the fitting direction. The inward flange part 34b is formed so as to abut or to be close to the automotive wheel side end surface 21b of the outer ring 21 when the core member 34 is fitted to the outer ring 21. In the fitting relation of the core member 34 and the outer ring 21, the former corresponds to the annular member of the present invention and the latter corresponds to the member to be fitted of the present invention.
The inside corner 21e and the outside corner 21f of the wheel side end surface 21d of the outer ring 21 are planely chamfered and are provided with the annular seal layers 21g, 21h formed with predetermined layer thickness “d” by applying the elastomeric agent and hardening it as mentioned above. When the core member 34 of the exterior seal 33 is fitted to the outer ring 21 along the direction of the outlined arrow, the annular seal layers 21g, 21h in a compressed state are interposed between the core member 34 and the outer ring 21. Therefore, the fitting portion of the core member 34 and the outer ring 21 is sealed and dirty water and the like which have reached the outer circumference 21i of the outer ring 21 are prevented from entering the bearing space 20a through the fitting portion.
a and
An inside corner 21j and an outside corner 21k of the automotive body side end surface 21b of the outer ring 21 are planely chamfered and are provided with annular seal layers 21m, 21n formed with predetermined layer thickness “d” by applying the elastomeric agent and hardening it as mentioned above. When the cylindrical parts 27a, 27g of the cap member 27 are fitted to the outer ring 21 along the direction of the outlined arrow, the annular seal layers 21m, 21n are interposed in a compressed state between the cap member 27 and the outer ring 21. Therefore, the fitting portion of the cap member 27 and the outer ring 21 is sealed and dust, dirty water and the like are surely prevented from entering by the cap member 27. In this case, double cylindrical parts 27a, 27g of the cap member 27 are fitted to the outer ring 21 so as to sandwich the outer ring 21 from outside and inside, so that a sealing structure with outstanding sealing performance is obtained by the synergetic effect of the fitting state and the sealing function of the annular seal layers 21m, 21n.
In the embodiment shown in
The inside corner 21j and the outside corner 21k of the automotive body side end surface 21b of the outer ring 21 are planely chamfered and are provided with the annular seal layers 21m, 21n formed with predetermined layer thickness “d” by applying the elastomeric agent and hardening it as mentioned above. When the cylindrical part 27g of the cap member 27 is fitted to the outer ring 21 along the direction of the outlined arrow, the annular seal layers 21m, 21n are interposed in a fitted state between the cap member 27 and the outer ring 21. Therefore, the fitting portion of the cap member 27 and the outer ring 21 is sealed and dust and dirty water are surely prevented from entering by the cap member 27.
The sealing structure for a fitting portion of the present invention is not limited to the exemplified embodiments. The sealing structure for a fitting portion of the present invention can be applied to fitting members which require sealing performance between the annular member and the member to be fitted. For example, the present invention can be applied to such a case that the member to be fitted is a shaft and a slinger as the annular member is directly fitted to the shaft. Although the embodiment in
Number | Date | Country | Kind |
---|---|---|---|
2009-157395 | Jul 2009 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2010/060773 | 6/24/2010 | WO | 00 | 12/19/2011 |