Bearing unit with cage
By introducing movable sectors and annular elastic elements into the bearing unit, the ball rolling element disengagement caused by axial loads and misalignment in high-speed and high-vibration bearing units is solved, and higher stability and reliability are achieved. And provide flexible maintenance solutions.
Patent Information
- Application Number
- CN202410881880.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-07-07
- Filing Date
- 2024-07-03
- Publication Date
- 2025-01-07
AI Technical Summary
In high-speed and high-vibration bearing units, when there is a high axial load or the shaft is not aligned with the bearing unit, the traditional cage may deform, causing the ball rolling element to be disassembled, causing the bearing unit to be disassembled.
Design a cage with movable sectors, through dovetail joints and annular elastic elements, allowing sectors to slide in the axial direction to cope with loads and misalignment, prevent deformation, and control the movement of sectors through mechanical end stroke components, ensuring The ball rolling element is maintained in its cavity position.
Effectively prevents ball rolling elements from being disengaged, improves the stability and reliability of the bearing unit, allows individual replacement of worn sectors without the need to replace the entire cage, and returns to position when misalignment and load effects disappear.
Smart Images
Figure CN119267441A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a bearing unit with a retaining cage. Background Art
[0002] Known bearing units with cages include:
[0003] - radial outer ring,
[0004] - radial inner ring,
[0005] - a plurality of rolling elements, in particular balls, are interposed between the two inner rings and the outer ring so that the inner rings and the outer rings can rotate relative to each other, and
[0006] - a retaining cage, which holds the balls in respective circumferential positions and further comprises a circular base frame and a plurality of tenons integral with the frame, the plurality of tenons being circumferentially spaced apart and in pairs defining a plurality of cavities for holding respective balls.
[0007] The base frame is a continuous structural element that extends circumferentially, forms a solid base, and provides the entire cage with the rigidity required to keep the balls equally spaced from each other. On the other hand, the tongues that receive the balls and hold them together must exhibit a substantially elastic behavior so as to spread apart to allow the balls to be inserted, and then substantially close around the balls to hold them inside the associated cavities.
[0008] These cages are typically used in high-speed, high-vibration bearing units, which are used both in the automotive industry, such as for power trains, and in the industrial industry, such as for machine tool spindles, and are typically made by injection molding polymer materials, including to compensate for poor lubrication conditions.
[0009] When bearing units with a cage, such as the known types described above, are used in applications where high axial loads are present or where there are misalignments between the shaft and the bearing unit, the cage may not deform significantly during relative rotation between the rings of the bearing unit to such an extent that the tongue is no longer able to retain the ball inside the cavity, resulting in an absolutely undesirable disassembly of the bearing unit. Summary of the invention
[0010] It is an object of the present invention to provide a bearing unit with a cage which does not have the above-mentioned disadvantages.
[0011] The invention therefore describes a bearing unit with a cage having movable sectors, the bearing unit having the features set out in the independent claim appended to this description.
[0012] Further preferred and / or particularly advantageous embodiments of the invention are described according to the features set out in the attached dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention is described below with reference to the accompanying drawings, which show non-limiting example embodiments of the invention, in which:
[0014] - Figure 1 is a partial cross section of a first preferred embodiment of a bearing unit according to the present invention,
[0015] - Figure 2 yes Figure 1 Axonometric view of the retaining cage of the bearing unit in
[0016] - Figure 3 yes Figure 2 A partial isometric bottom view of the cage in
[0017] - Figure 4 yes Figure 2 Enlarged isometric bottom view of the active sector of the cage in
[0018] - Figure 5 yes Figure 4 an enlarged isometric side view of the active sector in
[0019] - Figure 6 yes Figure 4 Different enlarged isometric side views of the active sector in . DETAILED DESCRIPTION
[0020] exist Figure 1 In the drawings, reference numeral 30 denotes as a whole a bearing unit according to a preferred embodiment of the present invention.
[0021] The bearing unit 30 has a central axis of rotation X and comprises:
[0022] - a radial outer ring 31 , preferably but not necessarily, the radial outer ring 31 is stationary,
[0023] - a radially inner ring 33, preferably but not necessarily, the radially inner ring 33 is rotating,
[0024] - a row 32 of rolling elements 34 between a radially outer ring 31 and a radially inner ring 33, and
[0025] A cage 40 for holding the rolling bodies 34 in position in the row 32 of rolling bodies.
[0026] Throughout the present specification and claims, unless otherwise stated, terms and expressions indicating positions and orientations such as "radial" and "axial" are to be understood with reference to the central rotation axis X of the bearing unit 30. For simplicity, the term "ball" may be used by way of example in the present specification and drawings instead of the more generic term "rolling element", and the same reference numerals will be used.
[0027] Reference Figure 2 According to the present invention, the retaining frame 40 includes a plurality of movable sectors 50, which are made of polymer material, are identical to each other and are arranged adjacent to each other in the circumferential direction. Each mobile sector has a first engagement portion 51 and a second engagement portion 52 at the end. The two engagement portions are shaped to define a dovetail joint, so that the first engagement portion 51 of the first movable sector 50' can be connected to the second engagement portion 52 of the second movable sector 50" adjacent to the first movable sector 50' in the circumferential direction to define a circumferential and radial constraint between the two movable sectors 50', 50". The same connection is reproduced for each pair of adjacent movable sectors to define a single retaining frame 40 made of polymer material, such as Figure 2 In the cage indicated in FIG. 4 , in a single cage 40 , all active sectors 50 are bound together both circumferentially and radially.
[0028] Each active sector 50 also has:
[0029] - a base rib 41 , defined by a flat annular structural member extending around the axis X,
[0030] - a pair of tenons 42, spaced apart in the circumferential direction and having an arcuate shape. The two tenons 42 have respective concave surfaces 42' facing each other,
[0031] A cavity 43 for holding a respective ball 34 . The cavity 43 is defined by a pair of tenons 42 .
[0032] Once all active sectors 50 have been connected circumferentially, the cage 40 has:
[0033] a base frame 44 which extends through 360° and is formed by the base ribs 41 of each active sector 50 ,
[0034] - a plurality of pairs of tenons 42, each pair of tenons belonging to an active sector 50, and
[0035] a plurality of cavities 43 , each defined by a respective pair of tenons 42 , the cavities 43 retaining all respective balls 34 in the row 32 of balls.
[0036] As described above, the dovetail joint between the two engaging portions 51, 53 of two circumferentially adjacent active sectors 50', 50" defines a circumferential and radial constraint between the two adjacent active sectors. However, such a joint provides the two adjacent sectors with a degree of freedom in the axial direction (within certain limits, as explained below), so that the active sectors can slide axially relative to each other in response to the different axial loads and / or misalignments that they may be subjected to during operation.
[0037] As in the present invention, a cage 40 with active sectors 50 that are independent of one another in the axial direction offers clear advantages in applications where there is misalignment of the shaft on which the bearing unit is mounted or where there are high axial loads that are not uniformly distributed in the circumferential direction. In fact, such a cage enables a single active sector to move in the axial direction to follow the movements caused by the misalignment and / or the axial loads, while the other active sectors remain in place. This prevents the cage 40 from deforming, eliminating the risk of the balls coming out of the corresponding cavities.
[0038] Advantageously, when the effects of misalignment and / or axial load no longer exist, the active sector 50 subjected to these effects can return to its original position. Figure 3 The cage 40 may include a metal annular elastic element 60 (eg an annular metal spring) which helps to hold the mobile sector in place and to return it to the proper position after an axial movement.
[0039] Reference Figure 4 , an annular elastic element 60 extends circumferentially inside a seat 53 formed in the base rib 41 of each active sector 50 .
[0040] Reference Figure 5 and Figure 6The first joint portion 51 of the dovetail joint between two adjacent active sectors comprises two shaped columns 51' which face each other radially and define an end space 54 and an intermediate space 54', wherein the radial width of the intermediate space 54' is greater than the radial width of the end space 54.
[0041] On the other hand, the second joint portion 52 of the dovetail joint includes an end edge 55 and a middle core 55 ′, wherein the radial width of the end edge 55 is greater than the radial width of the middle core 55 ′.
[0042] The radial width of the end edge 55 of the second engagement portion 52 is almost the same as the radial width of the middle space 54' of the first engagement portion 51, but a small radial gap is allowed. Similarly, the radial width of the middle core 55' of the second engagement portion 52 is almost the same as the radial width of the end space 54 of the first engagement portion 51, but a small radial gap is allowed.
[0043] A dovetail joint is formed by joining the following features:
[0044] - engaging the end edge 55 of the second engaging portion 52 in the intermediate space 54 ′ of the first engaging portion 51 , and
[0045] - Engage the middle core 55 ′ of the second engagement part 52 in the end space 54 of the first engagement part 51 .
[0046] This means that two adjacent sectors are joined together in the circumferential direction, since the end edge 55 of the active sector cannot escape from the end space 54 having the smaller radial width.
[0047] On the other hand, and as mentioned above, adjacent active sectors 50', 50" have a mutual freedom of movement. However, this movement will be limited and this is achieved by defining an abutment in the axial direction between a first stop surface 56 of the first engaging part 51 and a second stop surface 57 of the second engaging part 52. Despite the presence of the annular elastic element 60, this avoids the risk of the active sector detaching from the remaining "pack" of active sectors forming the cage.
[0048] Advantageously, the radially inner surface 58 of the second engagement portion 52 may be sized to absorb any radial loads transmitted between the first engagement portion and the second engagement portion.
[0049] In short, a bearing unit according to the present invention provided with a polymer retaining cage connecting a plurality of axially movable sectors together in the circumferential direction substantially reduces the risk of the bearing unit coming out of the polymer retaining cage when the bearing unit is subjected to high axial loads or when there is misalignment between the shaft and the bearing unit.
[0050] Furthermore, the disclosed solution does not require any modifications to the process of assembling the cage in the bearing unit and does not change the dimensions of the cage's frame compared to those of standard polymer cages.
[0051] On the other hand, the present solution offers the additional advantage of being able to replace individual worn active sectors instead of replacing the entire cage.
[0052] Finally, the axial movement of the active sectors of the cage is kept under control by simple mechanical end-of-travel means, and annular elastic elements facilitate the return of each individual sector affected by the axial movement to its original position.
[0053] In addition to the embodiments of the invention described above, there are many other variations. The embodiments are provided by way of example only and do not limit the scope of the invention, the application of the invention, or the possible configurations of the invention. In fact, although the description provided above enables those skilled in the art to implement the invention according to at least one exemplary configuration of the invention, many variations of the described components may be used without thereby departing from the scope of the invention as defined in the appended claims, literally and / or interpreted according to their legal equivalents.
Claims
1. A bearing unit (30) having a central axis of rotation (X) and comprising: - a radial outer ring (31), - a radial inner ring (33), - a row (32) of rolling elements (34) placed between the radially outer ring (31) and the radially inner ring (33), and - a cage (40) for retaining the rolling elements, The bearing unit (30) is characterized in that the retaining frame (40) includes a plurality of active sectors (50), which are equal to each other and are arranged adjacent to each other in the circumferential direction around the central rotation axis (X), and each active sector (50) has a corresponding first joining portion (51) and a corresponding second joining portion (52) for assembling itself with the corresponding second joining portion (52) and the corresponding first joining portion (51) of two circumferentially adjacent active sectors (50); each first joining portion (51) and each second joining portion (52) of each active sector (50) form corresponding circumferential constraints, corresponding radial constraints and corresponding axial degrees of freedom with each second joining portion (52) and each first joining portion (51) of the circumferentially adjacent active sectors (50).
2. The bearing unit (30) according to claim 1, characterized in that Each active sector (50) has: - a base rib (41) defined by a flat annular structural member extending around the axis (X), - a pair of tenons (42) spaced circumferentially apart and having an arcuate shape, and - a recess (43) defined by the pair of tenons (42) to retain the corresponding rolling element (34).
3. The bearing unit (30) according to claim 1 or 2, characterized in that: The cage (40) comprises a metallic annular elastic element (60) for maintaining the plurality of mobile sectors (50) in position and for restoring the axial position of each mobile sector (50) in the event of an axial movement.
4. The bearing unit (30) according to claim 3, characterized in that The annular elastic element (60) extends circumferentially inside a seat (53) obtained in each active sector (50) corresponding to the base rib (41).
5. The bearing unit (30) according to any one of the preceding claims, characterized in that The first engaging portion (51) comprises two shaped columns (51') facing each other in radial direction and defining an end space (54) and an intermediate space (54'), wherein the radial width of the intermediate space (54') is greater than the radial width of the end space (54).
6. The bearing unit (30) according to any one of the preceding claims, characterized in that The second engaging portion (52) includes an end edge (55) and a middle core (55'), wherein the radial width of the end edge (55) is greater than the radial width of the middle core (55').
7. Bearing unit (30) according to claims 5 and 6, characterized in that The radial width of the end edge (55) of the second joining portion (52) is substantially equal to the radial width of the middle space (54') of the first joining portion (51), and the radial width of the middle core (55') of the second joining portion (52) is substantially equal to the radial width of the end space (54) of the first joining portion (51).
8. The bearing unit (30) according to any one of the preceding claims, characterized in that The engagement portions (51, 52) define abutment between a first stop surface (56) of the first engagement portion (51) and a second stop surface (57) of the second engagement portion (52) in an axial direction.
9. The bearing unit (30) according to any one of the preceding claims, characterized in that The second engagement portion (52) has a radial inner surface (58) for absorbing radial loads transmitted between the first engagement portion (51) of the first active sector (50') and the second engagement portion (52) of the second active sector (50") circumferentially adjacent to the first active sector (50').