Patent Application
20080247692
This invention pertains to sliding bearings for shafts and the like, and more particularly to sliding bearings incorporating snap-in polymer inserts.
It is known to utilize a sliding bearing apparatus, including a bearing housing having a cylindrical opening extending longitudinally therethrough, in combination with a polymer bearing insert inserted into the cylindrical opening in the bearing housing, in conjunction with a shaft extending longitudinally through the bearing insert. Sliding bearing apparatuses of this type are disclosed in U.S. Pat. No. 6,113,275, to Blase, titled “Plain Bearing.”
Prior bearing apparatuses, such as the ones disclosed by Blase, include a bearing body having a slit extending along the entire length of its axis, and at least deformable zone, likewise extending along the entire length of the axis, to thereby allow the slit to be open so that the bearing body can be fitted to the shaft and removed from the shaft in a radial direction. Blase discloses bearing insert configurations having a plurality of projections which lock into an annular groove in a bearing housing, to secure the insert against axial movement within the housing, in combination with another projection, which engages a through-hole in the housing to secure the bearing body against radial movement within the housing.
Experience has shown that prior bearing arrangements, and polymer bearing inserts used therein, are undesirably complex to manufacture and install. For example, the bearing inserts disclosed in Blase are more difficult than is desirable to manufacture, due to the necessity for providing multiple protrusions which act individually for locking the insert against axial and radial movement respectively within the housing. Installation of the insert of Blase is also complicated by the necessity for using a two-step process, in which the protrusions which prevent axial movement within the housing are first engaged, and then, sequentially, the protrusion precluding radial motion is engaged with the housing.
The precise requirements for shape, and location of features such as the protrusions of Blase, have significantly limited the options available for molding or otherwise fabricating prior polymer sliding bearing inserts. Also, in the past, it has typically been necessary for manufactures and service organizations to carry a large inventory of differently shaped and sized bearing inserts which could typically be used only in a single application, such as a completely closed, or an open bearing arrangement.
In a commonly assigned patent application, filed concurrently herewith, under Attorney Docket No. 505948, the Applicant disclosed bearing inserts, apparatuses and methods providing considerable improvement over prior approaches, such as those disclosed by Blase, through use of a bearing insert having a single outwardly extending protrusion configured for retaining the bearing insert within a cylindrical opening in a bearing housing against movement in both the radial and axial directions simultaneously. Although the Applicant's co-pending patent application (Attorney Docket No. 505948) provides significant improvement over prior art approaches, such as the one disclosed in Blase, and has been shown to work well in a number of bearing applications, further improvement is desirable.
What is needed, therefore, is an improved sliding bearing apparatus and/or polymer bearing insert, and improved methods for constructing and using sliding bearing apparatuses or polymer bearing inserts of the type typically used therein.
The invention provides an improved bearing insert, apparatus, and method, through use of a bearing insert of polymer material defining a longitudinal axis along which the bearing insert may be net-shape-formed by extrusion. The invention further provides for retaining such an extrudable bearing insert within either open or closed bearing housings.
The term “extrudable,” as used with regard to the invention, is intended to mean that an insert, according to the invention, must be configured in such a manner that the insert can be net-shape-formed by extrusion along a longitudinal axis of the insert. It is contemplated, however, that, in some forms of the invention, an extrudable insert, according to the invention, may be formed through the use of some other process such as molding.
Through use of the extrudable bearing insert of the invention, excess complexity, cost, and difficulty of use experienced in prior bearing apparatuses, having bearing inserts including outwardly extending protrusions which could not be net-shape-formed by extrusion, are eliminated or significantly reduced.
In one form of the invention, an extrudable polymer bearing insert is provided, for a sliding bearing. The extrudable bearing insert is adapted for insertion into a substantially cylindrical, longitudinally oriented, opening in a bearing housing, for use with a shaft extending longitudinally through the cylindrical opening in the bearing housing, with the shaft having a radius, an outer diameter, and a corresponding circumference thereof. The bearing insert includes a body of polymer material defining a longitudinal axis of the insert along which the insert may be net-shape-formed by extrusion. The body also defines first and second spaced longitudinal edges of the insert, extending substantially parallel to the longitudinal axis of the insert. The body further defines a plurality of longitudinally extending bearing segments, joined to one another by flexible webs.
The bearing segments each define inner and outer substantially longitudinally extending surfaces thereof. The inner surface of each of the bearing segments has a longitudinally extending radiused recess therein, with the radius of the radiused recesses substantially matching the radius of the shaft, and formed for bearing against a portion of the circumference of the shaft. The outer surface of each of the bearing segments is formed in such a manner that, when the insert is disposed within the cylindrical opening in the bearing housing, the inner surfaces of the bearing segments, in combination with one another, substantially define a circumferentially interrupted bore having an internal radius substantially matching the radius of the shaft, and such that the longitudinal edges of the insert form a longitudinally extending opening therebetween.
In some forms of the invention, each of the bearing segments defines side walls thereof, with one of the side walls of each of a first and a second one of the bearing segments defining the first and second longitudinally extending edges of the insert. The bearing insert is further configured to be longitudinally trimmable along a side edge of another one or more bearing segments for forming an insert for an open bearing.
A bearing insert, according to the invention, may be configured to assume a substantially cylindrical form, in a free-standing state, when not inserted into the cylindrical opening of the bearing housing. Alternatively, a bearing insert, according to the invention, may be configured to assume a substantially non-cylindrical form in a free-standing state, when not inserted into the cylindrical opening in the bearing housing. In other forms of the invention, a bearing insert, according to the invention, may be configured to assume a substantially flat, planar form in a free-standing state, when not inserted into the cylindrical opening in the bearing housing.
Where the invention is practiced with an open bearing in which the bearing housing defines a longitudinally extending slot therein, opening outward from the cylindrical opening in the housing and defining first and second longitudinally extending edges of the slot in the housing, a bearing insert, according to the invention, may further include longitudinally extending locating flanges for securing the bearing insert within the housing of the open bearing. The bearing insert may include longitudinally extending first and second locating flanges, having backsides thereof extending outward from the first and second longitudinally extending edges of the insert to a point beyond the outer surface of the bearing segments, with the backsides of the locating flanges being adapted for substantially faying contact with the first and second longitudinally extending edges of the slot in the bearing housing of the open bearing.
In forms of the invention including locating flanges, for use with an open bearing arrangement, except for the locating flanges, the bearing insert may take a variety of alternative forms, in a free-standing state, including a substantially cylindrical form, a substantially non-cylindrical form, and a substantially flat planar form, when the bearing insert is not inserted into the cylindrical opening in the bearing housing.
In one form of a method, according to the invention, an extrudable bearing insert, in accordance with the invention, is formed by extruding the bearing insert along the longitudinal axis of the bearing insert. The method may further include extruding a body having an initial length greater than a desired axial length of the bearing insert, and cutting the body to the desired axial length of the bearing insert. In some forms of the invention, a body having a length several times greater than the desired axial length of the bearing insert may be formed by extrusion, molding, or any other appropriate process, and the method may further include cutting the bearing insert to length from the elongated body. In this manner, a single elongated body of polymer material may be utilized for forming a number of individual bearing inserts, with the individual bearing inserts having the same or differing axial lengths from one another. In this manner, inventory requirements may be reduced by producing standardized elongated bodies of material, and cutting bearing inserts of a desired length from the blanks to fulfill requirements for bearing inserts of various lengths.
In some forms of the invention, each of the bearing segments of the extrudable bearing insert defines sidewalls thereof, with one of the sidewalls of each of a first and a second one of the bearing segments defining the first and second longitudinally extending edges of the insert. The bearing insert is further configured to be longitudinally trimmable along a side edge of another one or more bearing segments for forming an insert of an open bearing.
A method, according to the invention, may include longitudinally trimming the bearing insert along a side edge of the another one of the another one or more bearing inserts. In this manner, an extrudable bearing insert, according to the invention, which was initially configured for use in a closed bearing, may be converted for use in an open bearing. This capability to convert a bearing insert initially formed for use in a closed bearing into an open bearing provides significant advantages in reduction of inventory, through practice of the invention.
The invention may also take the form of a bearing apparatus, including a bearing housing having a cylindrical opening extending substantially longitudinally therethrough, and an extrudable bearing insert adapted for insertion into the substantially cylindrically oriented opening in the bearing housing, for use with a shaft extending longitudinally through the cylindrical opening in the bearing housing, where the shaft has a radius, an outer diameter, and a corresponding circumference thereof. The bearing insert includes a unitary body of polymer material, defining a longitudinal axis of the insert along which the insert may be net-shape-formed by extrusion. The body also defines first and second spaced longitudinal ends of the insert, extending substantially parallel to the longitudinal axis of the insert. The body further defines a plurality of longitudinally extending bearing segments joined to one another by flexible webs.
The bearing segments each define inner and outer substantially longitudinally extending surfaces thereof. The inner surface of each of the bearing segments has a longitudinally extending radiused recess therein, with the radius of the radiused recess substantially matching the radius of the shaft, and configured for bearing against the portion of the circumference of the shaft. The outer surface of each of the bearing segments is formed in such a manner that, when the insert is disposed in the cylindrical opening in the bearing housing, the inner surfaces of the bearing segments, in combination with one another, substantially define a circumferentially interrupted bore having an internal radius substantially matching the radius of the shaft, and such that the longitudinal edges of the insert form a longitudinally extending opening therebetween.
In some forms of a bearing apparatus, according to the invention, an adhesive is disposed between the bearing insert and the housing, for attaching the bearing insert to the housing, to thereby retain the bearing insert within the cylindrical opening in the bearing housing.
In other forms of a bearing apparatus, according to the invention, the bearing insert further defines a longitudinal length thereof extending between first and second axial ends of the bearing insert, and the bearing housing has a longitudinal length, extending between first and second axial ends of the bearing housing. The bearing housing further includes at least one insert retaining feature extending substantially radially into the cylindrical opening in the bearing housing for engaging one of the axial ends of the bearing insert, to thereby preclude axial movement of the insert with respect to the bearing housing when the bearing insert is disposed within the cylindrical bore. In some forms of the invention, the insert retaining feature may include an annular flange disposed within the cylindrical opening in the bearing housing adjacent one of the axial ends of the bearing housing. The bearing housing may further include annular flanges disposed within the cylindrical opening in the bearing housing adjacent both axial ends of the bearing housing.
Where the bearing apparatus is an open bearing, the bearing housing may further define a longitudinally extending slot therein opening outward from the cylindrical opening in the housing, and defining first and second longitudinally extending edges of the slot in the housing. The bearing insert may further include longitudinally extending first and second locating flanges, having backsides thereof extending outward from the first and second longitudinally extending edges of the insert, to a point beyond the outer surface of the bearing segments, with the backsides of the locating flanges being adapted for substantially faying contact with the first and second longitudinally extending edges of the slot in the bearing housing. The first and second longitudinally extending edges of the housing may each include one or more depressions therein, and the locating flanges may include corresponding deformations therein configured for engaging the depressions on the longitudinally extending edges of the slot in the bearing housing. In a method, according to the invention, the deformations in the locating flanges in the bearing insert may be formed by application of ultrasonic energy to the locating flange at a position opposite from the corresponding depression in the edges of the slot in the bearing housing, to thereby cause a portion of the locating flange to deform into its corresponding depression in the longitudinally extending flange of the housing.
In some forms of the invention, an extrudable bearing insert for an open bearing does not include locating flanges. In such forms of the invention, a bearing housing, according to the invention, may further include one or more inwardly extending retaining elements, disposed adjacent the first and second edges of the longitudinally extending slot in the bearing housing, and adapted for operatively engaging the first and second longitudinal edges of the bearing insert, to thereby preclude radial movement of the insert within the cylindrical opening in the housing. These inwardly extending retaining elements may include longitudinally extending flanges. In some forms of the invention, for open bearings, the bearing housing includes one or more inwardly extending annular flanges at opposite axial ends of the cylindrical bore, in combination with longitudinally extending flanges adjacent the edges of the longitudinally extending slot in the housing, to thereby preclude both axial and radial movement of the extrudable bearing insert with respect to the bearing housing.
In some forms of the invention, a bearing housing, according to the invention, may include at least one insert retaining feature extending substantially radially into the cylindrical opening in the bearing housing for engaging the bearing insert, to thereby preclude movement of the insert with respect to the bearing housing when the bearing insert is disposed within the cylindrical bore. The bearing insert may further include a retaining recess therein cooperatively configured for operatively engaging the insert retaining feature extending form the housing. In embodiments of the invention where the extrudable bearing insert is otherwise net-shape-formed by extrusion, a secondary operation is performed on the extruded bearing insert to form the retaining recess therein. In embodiments of the invention where the extrudable bearing insert is molded, for example, it is contemplated that the retaining recess may be molded into the insert.
The invention may also take the form of a method for constructing, utilizing or replacing a bearing insert or bearing housing, according to the invention, or a method for constructing, utilizing or repairing a bearing insert, a bearing housing, or a bearing apparatus, according to the invention.
Other aspects, objectives and advantages of the invention will be apparent from the following detailed description and accompanying drawings of exemplary embodiment of the invention.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
The bearing insert 106 is adapted for insertion into the substantially cylindrical longitudinally oriented opening 104 in the bearing housing 102, and is configured for use with a shaft (not shown) extending longitudinally through the bearing insert 106 and the cylindrical opening 104 in the bearing housing 102, with the shaft having a radius, an outer diameter, and a corresponding circumference thereof, with the radius outer diameter and circumference of the shaft not being shown in the drawings for the sake of clarity of illustration.
As best seen in
As best seen in
The bearing segments 124 each define radially inner and radially outer surfaces 128, 130 thereof. The radially inner surface 128 of each of the bearing segments 124 has a longitudinally extending radiused recess 132 therein, with each of the radiused recesses 132 having a radius 134 substantially matching the radius of the shaft, and configured for bearing against a portion of the circumference of the shaft.
The radially outer surfaces 130 of each of the bearing segments 124, is formed in such a manner that, when the insert 106 is disposed within the cylindrical opening 104 in the bearing housing 102, the radially inner surfaces 128 of the bearing segments 124, in combination with one another, substantially define a circumferentially interrupted bore 136, having an internal radius 134 substantially matching the radius of the shaft, and such that the longitudinal edges 118, 120 of the insert 106 form the longitudinally extending slot 122 therebetween.
In
In some embodiments of the invention, the insert 106 may be configured to substantially assume a non-cylindrical form in a free-standing state, when not inserted into the cylindrical opening 104 in the bearing housing 102. Such a non-cylindrical shape may be more advantageously formed, or provide a greater snap-fit force for retaining the insert 106 within the housing 102.
With particular regard to ease of manufacturing, and to provide a substantial advantage in the form of a reduction in the space required for handling inventory, in addition to providing a form which is more readily shippable, as a spare part, for example,
Prior to inserting the embodiment of the insert 106 shown in
The first exemplary embodiment of the bearing apparatus 100, according to the invention, also includes an adhesive (not shown) disposed between the bearing insert 106 and the housing 102, for attaching the bearing insert 106 to the housing 102 for retaining the bearing insert 106 within the cylindrical opening 104 in the bearing housing 102.
The bearing housing 202 further includes a pair of insert retaining features, in the form of a pair of annular flanges 222 (only one of which is visible in
The bearing insert 206 is configured to include a longitudinally extending slot 224 therein, in the same manner as described above with regard to the slot 122 in the first exemplary embodiment of the extrudable bearing insert 106. To insert the bearing insert 206 into the cylindrical opening 204 in the bearing housing 202 of the second exemplary embodiment 200 of the invention, the edges of the longitudinally extending slot 224 in the bearing insert 206 are radially offset slightly from one another, and the bearing is constricted slightly about the longitudinal axis 214, so that the bearing insert 206 may slide past the annular flange 222 at one end of the bearing housing 202 and into the interior of the bearing housing 202. Once inside the bearing housing 202, the bearing insert 206 is released and expands outward into contact with the interior wall of the housing 202 defining the cylindrical opening 204.
In embodiments of the invention subjected primarily to axial motion of the shaft through the bearing insert, the bearing insert 206 may not need to be further attached to the bearing housing 202. The annular flanges 222 at the ends of the cylindrical opening 204, will bear against the ends 210, 212 of the bearing insert 206, to thereby preclude axial movement of the bearing insert 206 out of the housing 202.
Alternatively, in other embodiments of the invention, and in particular where it is desirable to preclude radial movement of the bearing insert 206 inside of the housing 202, the bearing apparatus 200 may further include an adhesive disposed between the bearing insert 206 and the housing 202.
From a comparison of
Close inspection of the insert 304 of the second embodiment, as shown in
Those having skill in the art will recognize, therefore, that the second exemplary embodiment of the insert 304 may be alternatively formed, in various embodiments, either as shown in
The third exemplary embodiment of the bearing apparatus 300, according to the invention, may also include an adhesive (not shown), disposed between the bearing insert 304 and the bearing housing 302, for attaching the bearing insert to the interior wall of the housing 302 defining the cylindrical opening 306. Alternatively, the third exemplary embodiment of the invention may incorporate annular flanges (not shown) at opposite ends of the cylindrical opening 306, similar to those flanges 222 described above in relation to the second exemplary embodiment 200 of the invention, for axially retaining the bearing insert 304, in combination with the adhesive (not shown) disposed between the bearing insert 304 and the bearing housing 302.
As illustrated in
The bearing insert 512, is generally similar to the bearing insert 304, described above in relation to the third exemplary embodiment 300 of the invention, with the exception that the bearing insert 512 of the fifth exemplary embodiment of the invention 500 also includes longitudinally extending first and second locating flanges 514, 516 having backsides 518, 520 thereof, extending outward from the first and second longitudinally extending edges of the insert 512 beyond the outer surface of the bearing segments of the insert 512, with the backsides 518, 520 of the locating flanges 514, 516 adapted for substantially faying contact with the first and second longitudinally extending edges 508, 510 of the slot 504 in the bearing housing 502, in the manner best illustrated in
As shown in
As indicated in
As will be understood, from an examination of
In forms of the invention including locating flanges, such as the flanges 514, 516 of the fifth exemplary embodiment 500 of the invention, it will be further understood that various combinations of features described hereinabove, when utilizes separately or in various combinations thereof, for retaining the insert 512 within the housing 502. For example, the bearing insert 512 may be secured within the housing 502 by use of an adhesive rather than the engagement of the deformations 524 with the depressions 522. The housing 502 may include annular flanges at opposite ends of the cylindrical opening, in some embodiments of the invention.
As shown in
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventor for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventor intends for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
