Patent Application
20240352971
The present disclosure is directed to a rolling-element bearing cage, a rolling-element bearing, a vehicle, and a method for assembling a rolling-element bearing cage.
There are conventional cages that are one-part and snap into the bearing. They are comprised structurally of a lateral ring with cantilevered crosspieces attached thereto that delimit the cage pockets. In radial bearings, the cantilevered crosspieces are subjected to a centrifugal force due to the rotational speed. At high rotational speeds, the crosspieces bend radially outward. The pocket geometry thereby changes, and a rubbing of the cage on the outer ring of the bearing can result. In the industry, this is known as umbrella effect or “umbrella effect,” and limits the bearing rotational speed.
One solution is to optimize a one-part conventional cage by minimizing the mass subjected to the centrifugal force and simultaneously maximizing the rigidity of the lateral ring. An example thereof is a cage that is used for vehicles with electric propulsion
Another solution is two cage halves that are manufactured from brass or fabric-reinforced phenolic resin and riveted together.
The publication WO 2007/135305 A1 (family member of U.S. Pat. No. 8,157,449) further discloses a cage without a second lateral ring.
Furthermore, in known roller bearings, the cantilevered crosspieces that delimit cage pockets are provided on the ends with snap arms that snap into a lateral ring. Here in the individual snap connections, snap arms are disposed on a radially upper side and a radially lower side.
An aspect of the disclosure is in particular to provide a rolling-element bearing cage of the above-described type that is designed for high rotational speeds and that has a design that is also suitable for relatively small bearings.
Disclosed is a rolling-element bearing cage with a first cage ring that includes an axial extension and at least one snap arm disposed directly on the projection and at least one second cage ring having at least one attachment portion to which the at least one snap arm is snapped to form a snap connection.
In the disclosed embodiments there is a section extending in the axial direction of the rolling-element bearing cage in which each snap arm of the first cage ring disposed directly on the extension has a smaller distance from a central axis of the rolling-element bearing cage extending in the axial direction of the roller-element bearing cage than the attachment region. An “axial” extension shall be understood in particular to mean an extension in the axial direction of the rolling-element bearing cage. Further, that “a section extending in the axial direction of the rolling-element bearing cage in which each snap arm of the first cage ring disposed directly on the extension has a smaller distance from a central axis of the rolling-element bearing cage extending in the axial direction of the roller-element bearing cage than the attachment region” shall be understood in particular to mean that in the geometric sense there is an imaginary line that is part of the central axis, extending in the axial direction of the rolling-element bearing cage, of the rolling-element bearing cage, so that the part disposed directly on the extension of the snap arm of the first cage ring, which part lies between a first imaginary plane that is cut vertically from the central axis and which includes a first end point of the line and a second imaginary plane which is cut vertically from the central axis and which includes a second end point of the line, has a shorter distance from the central axis than the part of the attachment region that is disposed between the first plane and the second plane. By a “central axis” of the rolling bearing cage extending in the axial direction of the rolling bearing cage is to be understood in particular a straight line extending in the axial direction of the rolling bearing cage and having a center of mass of the rolling bearing cage. It can thereby be achieved that the rolling-element bearing cage is designed for high rotational speeds and has a design that is also suitable for relatively small bearings. In particular, it can be achieved that the snap arm and the extension experience only a very small deflection away from the central axis in the radial direction when the rolling-element bearing cage rotates quickly. Furthermore, in particular a compact design in the radial direction can be achieved.
In particular, the extension can form a part of a boundary of a pocket of the rolling-element bearing cage.
Furthermore, with respect to a circumferential direction of the rolling-element bearing cage, the snap arm is disposed between two pockets of the rolling-element bearing cage disposed adjacent in the circumferential direction, and a first of the pockets is delimited by a lateral ring of the first cage ring and a lateral ring of the second cage ring and a first crosspiece of the rolling-element bearing cage and a second crosspiece of the rolling-element bearing cage, wherein the second crosspiece has a greater distance from the snap arm than the first crosspiece, wherein the snap arm and/or the extension are or is disposed spaced from the first crosspiece. It can thereby be achieved that the extension can be fully designable according to optimal functional requirements of the snap connection.
Advantageously, the fastening area has a surface area of the rolling bearing cage that is on the outside with respect to a radial direction of the rolling bearing cage. As a result, a low expansion of the rolling bearing cage in the radial direction can be achieved.
Advantageously, the axial portion is an entire axial extent portion of the fastening portion. Through this, a simple design of the snap connection can be achieved.
Furthermore, the first cage ring and the second cage ring may be configured identical. In this way, a cost-effective manufacturability of the rolling-element bearing cage can be achieved. In particular, the cage rings can be produced using a single injection mold.
The second cage ring is advantageously free of snap arms. A simple assembling can thereby be achieved. In particular, the first cage ring and the second cage ring can be attached to each other by snapping when the rolling-element bearing cage includes an odd number of pockets.
The snap arm preferably tapers with increasing distance to the extension. It can thereby be achieved that the snap arm is manufacturable by injection molding. In particular, a simple removing can be achieved of the snap arm from an injection mold after the injection molding.
The snap arm and a further snap arm of the rolling-element bearing cage are advantageously disposed between two pockets adjacent in the circumferential direction of the rolling-element bearing cage. A stable attaching of the two cage rings to each other can thereby be achieved.
Furthermore, a rolling-element bearing is disclosed, in particular a ball bearing with a rolling-element bearing cage as described above.
Furthermore, a vehicle is disclosed with electric propulsion and with the rolling-element bearing, wherein the rolling-element bearing supports a shaft of an electric motor of the vehicle, which shaft (drive shaft) is provided to at least contribute to the propulsion of the motor vehicle. Even with a relatively small design of the rolling-element bearing, high rotational speeds of the shaft or high rotational speeds in the transmission can thereby be achieved.
In addition, a method is disclosed for assembling a rolling-element bearing cage, in particular a rolling-element bearing cage as described above, in which a first cage ring is attached to a second cage ring by a snap connection, wherein all snap arms of the first cage ring that are provided for realizing the snap connection are deflected radially inward during a producing of the snap connection as compared to an unassembled state in which the first cage ring is disposed spaced from the second cage ring. It can thereby be achieved that the rolling-element bearing cage is designed for high rotational speeds and has a design that is also suitable for relatively small bearings. In particular, it can be achieved that the snap arms and cage pocket boundaries experience only a very small deflection away from the central axis in the radial direction when the rolling-element bearing cage rotates quickly. Furthermore, in particular a compact design in the radial direction can be achieved.
When producing the snap connection, partial regions of a lateral ring, which is part of the first cage ring and in an assembled state of the rolling-element bearing cage is disposed on an axial end of the rolling-element bearing cage, are deflected relative to other partial regions of the lateral ring at least in an axial direction of the first cage ring. A large radial displacement of the snap arms can thereby be achieved during a producing of the snap connection. In particular, the deflecting can occur such that the first-mentioned partial regions each perform a rotational movement.
Further advantages arise from the following description of the drawings. Exemplary embodiments of the invention are depicted in the drawings. The drawings, the description, and the claims contain numerous features in combination. The person skilled in the art will also advantageously consider the features individually and combine them into further meaningful combinations.
The first cage ring 12 and the second cage ring 22 are identically formed. The second cage ring includes a recess 48 into which the snap arm 20 is introduced and snapped during a producing of the snap connection. A snap arm 34 of the second cage ring 22 is directly adjacent to the recess 48. During the producing of the snap connection, the snap arm 34 is introduced and snapped into a recess (not depicted) of the first cage ring 12; the recess is directly adjacent to the snap arm 20. The two snap arms 20, 34 are thus disposed between the pocket 18 and a pocket 36, which are disposed adjacent in the circumferential direction of the rolling-element bearing cage and are thus directly consecutive. Between all adjacent pockets of the rolling-element bearing cage, two snap arms are disposed that form a snap connection as described for the snap arm 20. All snap arms are formed identically.
In comparison to a radially outer surface of the extension 14, the snap arm 20 is disposed radially inward. A tip of the snap arm 20 forms a part of an end surface of the second cage ring 22.
In the
Overall, the first cage ring 12 is attached to the second cage ring 22 by a snap connection, which is realized by the individual snap connection of the individual snap arms of the rolling-element bearing cage. An assembling of the rolling-element bearing cage consists in attaching the cage ring 12 to the cage ring 22 by the snap connection. During the producing of this snap connection, the cage ring 12 is pressed against the cage ring 22 such that in comparison to an unassembled state in which the first cage ring is disposed spaced from the second cage ring, all snap arms of the first cage ring and all snap arms of the second cage ring 22 are deflected radially inward, and, with a further pressing of the cage ring 12 against the cage ring 22, snap in.
During the assembling of the rolling-element bearing cage 10, partial regions of the lateral ring 40, which is part of the first cage ring 12 and in an assembled state of the rolling-element bearing cage is disposed on an axial end 41 of the rolling-element bearing cage, are deflected during a producing of the snap connection relative to other partial regions 42 of the lateral ring 40 at least in an axial direction of the first cage ring 12. A larger deflection of the snap arms radially inward is thereby made possible. A force that is required for the producing of the snap connection thus depends on a rigidity of the lateral ring 40. The deflecting of the partial regions 38 is effected by them each performing a rotational movement.
In an installed state, the rolling-element bearing cage is part of a ball bearing. The ball bearing is in turn part of a vehicle with electric propulsion and supports there a shaft of an electric motor, which is provided to provide at least a contribution to a propulsion of the vehicle. Alternatively, the ball bearing can also be part of a transmission of the vehicle, which transmits a propulsion from the electric motor to a differential of the vehicle.
The cage ring 12 and the cage ring 22 are each configured one-piece. Each of the two cage rings can be produced in a single injection molding process, which is cost-effective, or by 3D printing. In the injection molding processes, molds without movable parts can be used, whereby a particularly cost-effective production is possible. Furthermore, after the injection molding processes, rods can be introduced into the injection molds, whereby a simple demolding is possible.
The rolling-element bearing cage can in particular be formed from polyamide 66 or polyetheretherketone. Here a reinforcing by fibers can be present, and specifically in particular a reinforcing by glass fibers and/or carbon fibers. Furthermore, the rolling-element bearing cage can also be comprised of a metallic material, such as in particular brass or aluminum. The rolling-element bearing cage can be homogeneously constructed from a single material.
Due to the fact that the two cage rings are attached to each other by snapping, a simple, fast, and cost-effective assembling of the rolling-element bearing cage is possible.
The rolling-element bearing cage is in particular robust in comparison to a one-part cage because a suitability for high rotational speeds is present. Further, when the cage is rotated, the snap arms 20,34 are forced radially outward, increasing a circumferential attachment of the snap arms and thus the cage ring 12 to the cage ring 22 by improving a frictional connection between the snap arms and the cage ring 22 through an increased force. Furthermore, during the rotation the snap connection becomes tighter.
The snap arm 20 tapers with increasing distance from the extension 14 in an alternative embodiment according to
In the rolling-element bearing cage 10 there is no umbrella effect. Furthermore, the design of the rolling-element bearing cage 10 is suitable when the rolling-element bearing cage must be small, because there is no snap arm arranged on a radially outer side of the mounting portion 24, which is attached to the extension 14. Installation space is thereby saved in the radial direction.
The rolling-element bearing cage 10 is comprised of the cage rings 12, 22.
After a final assembly, the rolling-element bearing cage 10 can be part of any device in which it enables rotation at high speed. Here the rolling-element bearing cage can have comparatively small dimensions. For example, the rolling-element bearing cage can be used in a supporting of a shaft of a motor, or in special vacuum pumps.
Alternative exemplary embodiments are depicted in
Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved rolling element bearing cages and assemblies including such cages.
Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.
All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.
