TENSIONER HAVING A ROLLER ASSEMBLY WITH A BEARING AND A ROLLER HAVING FEATURES FOR AXIALLY SECURING AN OUTER BEARING RACE OF THE BEARING TO THE ROLLER

A tensioner with a pivoting arm and a roller assembly having a bearing and a roller. The bearing supports the roller relative to the arm for rotation about a roller axis that is parallel to but offset from the pivot axis. The roller has a bearing socket and one or more locking tabs. The bearing socket has an annular bearing surface and a stop that is disposed radially inwardly from the annular bearing surface. Each of the locking tabs is resiliently coupled to an adjacent portion of the roller. The bearing is received in the bearing socket such that the outer bearing race of the bearing is disposed axially between the stop and the distal ends of each of the locking tabs. The locking tabs limit axial movement of the outer bearing race along the roller axis in a direction away from the stop.

FIELD

The present disclosure relates to tensioner having a roller assembly with a bearing and a roller having features for axially securing an outer bearing race of the bearing to the roller.

BACKGROUND

Tensioners of the type that are employed to tension belts commonly have a pivoting arm to which a roller assembly is rotatably mounted. The roller assembly is employed to engage the belt and commonly includes a roller and a bearing that supports the roller for rotation. The roller and the outer bearing race of the bearing can be coupled in various different manners. For example, the outer bearing race can be press-fit into the roller. As another example, the roller can be formed of a plastic material and can be overmolded onto the outer bearing race. In instances where the roller is formed out of a sheet metal, as when the roller is manufactured in a drawing operation, other more costly means of retention, such as snap rings or adhesives have been used. In the case of adhesives, care must also be taken to ensure that the adhesive is fully cured before axially directed loads can be applied to the roller assembly. Moreover, the aforementioned means of retaining the bearing to the roller are relatively sensitive to axially directed loads that can be applied to the roller assembly by the belt in some instances. In such cases, it is possible for the bearing to separate and move axially relative to the roller.

In view of the above drawbacks, there is a need in the art for a tensioner with an improved roller assembly that is easy to manufacture and assemble and is resistant to axially directed forces.

SUMMARY

In one form, the present disclosure provides a tensioner for tensioning a belt. The tensioner includes a base, an arm, which is coupled to the base for movement relative to a movement axis, and a roller assembly having a bearing and a roller. The bearing supports the roller relative to the arm for rotation about a roller axis that is spaced apart from the movement axis. The bearing has an outer bearing race, an inner bearing race, and a plurality of bearing elements that are disposed radially between the outer and inner bearing races. The roller has a wall member that defines a roller member, a bearing socket and one or more locking tabs. The roller member has an annular roller surface that is disposed concentrically about the roller axis and is configured to engage the belt. The bearing socket has an annular bearing surface, which is disposed concentrically within the annular roller surface, and a stop that is disposed radially inwardly from the annular bearing surface. Each of the locking tabs has a proximal end, which is resiliently coupled to an adjacent portion of the wall member, and a distal end that projects radially inward from the proximal end and the annular bearing surface. The bearing is received in the bearing socket such that the outer bearing race is disposed axially between the stop and the distal ends of each of the locking tabs. The one or more locking tabs limit axial movement of the outer bearing race along the roller axis in a direction away from the stop.

In another form, the present teachings provide a method for assembling a tensioner. The method includes: providing a bearing with an outer bearing race; inserting the bearing into a bearing socket in a roller along a roller axis such that distal ends of a plurality of locking tabs formed on the roller are urged in a radially outward direction by an outer circumferential surface of the outer bearing race; seating the bearing in the bearing socket such that the distal ends of the locking tabs release the outer circumferential surface of the outer bearing race and move radially inwardly to limit movement of the outer bearing race axially along the roller axis in a direction toward the distal ends of the locking tabs; securing the bearing to an arm member such that an annular roller surface of the roller is rotatable about the roller axis relative to the arm member; and coupling the arm member to a base for pivoting motion about a pivot axis.

DETAILED DESCRIPTION

With reference toFIGS. 1 and 2, a tensioner constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral10. The tensioner10can include a base12, an arm14and a roller assembly16. The base12is configured to be fixedly coupled to a suitable structure, such as the block of an internal combustion engine (not shown). The base12includes a pivot pin18that defines a pivot axis20. The pivot pin18defines a pin aperture22that is configured to receive a fastener (not shown) therethrough to permit the base12to be fixedly but removably coupled to the suitable structure. The arm14can be coupled to the base12for pivoting motion about a pivot axis20. A suitable biasing mechanism, such as a torsion spring24, can be employed to exert a force or torque onto the arm14to bias the arm14about the pivot axis20in a predetermined direction. In the particular example shown, the torsion spring24is disposed in a load path between (and directly engages) the base12and the arm14, but it will be appreciated that the torsion spring24could have been disposed between the arm14and another structure, such as a second arm (not shown) that is pivotably mounted on the pivot pin18.

With reference toFIGS. 2 through 4, the roller assembly16can include a bearing30and a roller32. The bearing30can be a conventional type of bearing, such as a rolling element bearing having an outer bearing race34, an inner bearing race36and a plurality of bearing elements38that are disposed between the outer and inner bearing races34and36. The bearing elements38can be sized and shaped in a desired manner, but are shown as spherical balls in the example provided. Optionally, the bearing30can be configured to provide axial as well as radial support and may take the form of an angular contact bearing.

InFIGS. 5 and 6, the roller32can have a wall member40that defines a roller member44, a bearing socket46and one or more locking tabs48. The roller32can be unitarily and integrally formed in a casting, rolling, pressing (e.g., stamping, drawing) or molding operation and can be formed from any desired metal or plastic material. The roller member44can have an annular roller surface50that can be disposed concentrically about the roller axis—and which is configured to engage the belt. In the example shown, the annular roller surface50is a flat cylindrical surface, but it will be appreciated that the annular roller surface50could be shaped differently. For example, the annular roller surface50could define a plurality of V-shaped peaks (not shown) that are spaced apart from one another across the annular roller surface50. Alternatively, the annular roller surface50could be configured in a sprocket-like manner to engage a chain or could have teeth that can be configured to engage a toothed belt.

The bearing socket46can have an annular wall56and a stop58. The annular wall56can have an annular bearing surface60that can be disposed concentrically within the annular roller surface50. The stop58can be disposed radially inwardly from the annular bearing surface60. In the example shown, the stop58is formed by a segment of the wall member40that extends radially inward from the annular bearing surface60.

The bearing socket46can be fixedly coupled to the roller member44in any desired manner. In the example shown, a transition section64of the wall member40fixedly couples the bearing socket46to the roller member44. A portion66of the transition section64is frustoconical in shape and diverges outwardly from a roller axis68with increasing radial distance from the annular wall56. In the example provided, the transition section64includes fillet radii70at the radially outer and inner ends of the frustoconical portion66that couple the frustoconical portion66to the roller member44and the bearing socket46respectively. Configuration of the roller32in this manner permits the roller32to be fabricated in a deep drawing operation.

With reference toFIGS. 7 and 8, each of the locking tabs48can have a proximal end80, which is resiliently coupled to an adjacent portion of the wall member40, and a distal end82that projects radially inward from the proximal end80and the annular bearing surface60. In the example shown, a slotted aperture86is formed in the wall member40about a perimeter of each of the locking tabs48. The slotted aperture86can be formed when the wall member40is pierced or cut to form the locking tabs48, or when the roller32is cast or molded.

With reference toFIGS. 6 through 8, the bearing30is received into the bearing socket46such that the outer bearing race34is non-rotatably coupled to the annular wall56of the bearing socket46and the outer bearing race34is disposed axially between the stop58and the distal ends82of each of the locking tabs48. An outer circumferential surface90of the outer bearing race34can optionally be engaged to the annular bearing surface60in a press-fit manner. Additionally or alternatively, an adhesive material can be employed to fixedly couple the outer bearing race34to the annular bearing surface60.

The locking tabs48are configured to limit axial movement of the outer bearing race34along the roller axis68in a direction away from the stop58, while the stop58similarly limits axial movement of the outer bearing race34along the roller axis68in a direction away from the distal ends82of the locking tabs48. Optionally, the distal ends82of the locking tabs48can abut an axial end of the outer bearing race34that is opposite the axial end of the outer bearing race34that abuts the stop58. Alternatively, one or more spacing elements (not shown) can be disposed axially between the stop58and the outer bearing race34and/or between the distal ends82and the outer bearing race34.

Returning toFIG. 2, a threaded fastener100can be received through the inner bearing race36and can be secured to the arm14to fixedly couple the inner bearing race36to the arm14. It will be appreciated that the bearing30supports the roller32relative to the arm14for rotation about the roller axis68, which is parallel to but offset from the pivot axis20.

Returning toFIG. 6, a belt B is configured to contact the annular roller surface50in a contact zone Z. The annular roller surface50has an area that is greater than an area of the contact zone Z. The contact zone Z is centered along the roller axis68about the bearing elements38of the bearing30.

With reference toFIGS. 6 and 8, a method for assembling a tensioner can include: providing a bearing30with an outer bearing race34; inserting the bearing30into a bearing socket46in a roller32along a roller axis68such that distal ends82of a plurality of locking tabs48formed on the roller32are urged in a radially outward direction by an outer circumferential surface90of the outer bearing race34; seating the bearing30in the bearing socket46such that the distal ends82of the locking tabs48release the outer circumferential surface90of the outer bearing race34and move radially inwardly to thereby limit movement of the outer bearing race34axially along the roller axis68in a direction toward the distal ends82of the locking tabs48; securing the bearing30to an arm14such that an annular roller surface50of the roller32is rotatable about the roller axis68relative to the arm14; and coupling the arm14to a base12for pivoting motion about a pivot axis20.