Bearing cage with limited skew
By introducing a cage design with a Rayleigh step array into the bearing assembly, hydrodynamics is used to counteract the skewness of the rolling elements, thus solving the friction and heat problems of the bearing assembly at high speeds and improving the high-speed operation performance of the bearing assembly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- THE TIMKEN CO(US)
- Filing Date
- 2022-04-15
- Publication Date
- 2026-05-19
AI Technical Summary
Existing bearing assemblies lack effective devices to control the orientation of rolling elements under high-speed operation, leading to misalignment, increased friction, and heat generation, which damages the bearing assembly.
The cage design employs a Rayleigh step array, which generates hydrodynamic force to counteract the skewness of the rolling elements by interacting with the lubricant through the Rayleigh step array within the roller housing. The cage includes a first axial end ring, a second axial end ring, and a bridge portion, the surface of which is provided with a Rayleigh step array to generate hydrodynamic force within the fluid.
It effectively counteracts the misalignment of rolling elements, reduces friction and heat, and improves the high-speed operating performance of bearing assemblies, making it suitable for high-speed rotating environments such as electric vehicle power systems.
Smart Images
Figure CN117157467B_ABST
Abstract
Description
[0001] Cross-references to related applications
[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 175,886, filed April 16, 2021, the entire contents of which are incorporated herein by reference. Technical Field
[0003] This invention relates to bearing assemblies, and more particularly to bearing assemblies including bearing cages that restrict the skewness of rolling elements. Background Technology
[0004] Most bearing assemblies lack a mechanism to control the orientation of the rolling elements during operation. In some cases, high-speed operation can cause bearing misalignment, generating excessive friction and heat, which can damage the bearing assembly. Summary of the Invention
[0005] In one aspect, the present invention provides a rolling element bearing assembly cage for spaced out a plurality of rolling elements during operation of the rolling element bearing assembly about a central axis of rotation. The cage includes a first axial end ring, a second axial end ring, and a plurality of bridge portions extending between the first and second axial end rings. The plurality of bridge portions define a roller receiving portion therebetween. At least one of the plurality of bridge portions includes a Rayleigh step array disposed on its surface. This surface faces the interior of the roller receiving portion.
[0006] In another aspect, the present invention provides a cage for spaced-apart rolling elements in a rolling element bearing assembly containing a working fluid. The cage includes a first axial end ring, a second axial end ring, a central axis of rotation extending centrally through the first and second axial end rings, and a plurality of roller receptacles circumferentially spaced around the cage. Each of the plurality of roller receptacles is configured to receive a rolling element therein. At least one of the plurality of roller receptacles includes a Rayleigh step array configured to selectively generate hydrodynamic forces within the working fluid in response to a skew angle between the axis of rotation of the rolling element within the roller receptacle and the central axis of rotation.
[0007] In another aspect, the present invention provides a rolling element bearing assembly including an inner ring, an outer ring, a plurality of rolling elements disposed between the inner and outer rings, and a cage disposed between the inner and outer rings. The cage includes a plurality of roller receptacles in which the rolling elements are located. The plurality of roller receptacles are configured to circumferentially space the rolling elements around the rolling element bearing assembly. The roller receptacles include an array of Rayleigh steps configured to align the rolling elements within the roller receptacles.
[0008] In another aspect, the present invention provides a method of operating a rolling element bearing assembly. The method includes: providing an inner ring, an outer ring, a plurality of rolling elements disposed between the inner and outer rings, and a cage configured to circumferentially space the plurality of rolling elements around the rolling element bearing assembly. The cage includes a plurality of roller receptacles in which the rolling elements are located. Each roller receptacle includes a Rayleigh step array. The method further includes: rotating the outer ring relative to the inner ring while the rolling elements are in rolling contact with the outer and inner rings, and generating hydrodynamic forces on the rolling elements using the Rayleigh step array in response to skewness of the rolling elements relative to the axis of rotation of the rolling element bearing assembly.
[0009] Other features and aspects of the invention will become apparent from the following detailed description and accompanying drawings. Attached Figure Description
[0010] Figure 1 This is a perspective view of the bearing assembly.
[0011] Figure 2 This is a schematic diagram showing a bearing assembly with skewed rolling elements.
[0012] Figure 3 yes Figure 1 A side view of a roller housing of a bearing assembly.
[0013] Figure 4 It is along Figure 3 The cross-sectional view taken from section line 4-4 in the figure.
[0014] Figure 5A A schematic side view of a rolling element undergoing deflection in a first direction is shown.
[0015] Figure 5B A schematic side view of a rolling element undergoing deflection in a second direction is shown.
[0016] Figure 6 This is a perspective view of a bearing cage including a single rolling element according to an embodiment of the present disclosure.
[0017] Before explaining any embodiments of the invention in detail, it should be understood that the invention is not limited in its application to the details of the construction and arrangement of the components set forth in the following description or shown in the following drawings. The invention can have other embodiments and can be practiced or performed in various ways. Moreover, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. Detailed Implementation
[0018] Figure 1A bearing assembly 4 is shown, comprising an inner ring 8, an outer ring (not shown), and a plurality of circumferentially distributed rolling elements 12 positioned between the inner and outer rings. The inner and outer rings share a common bearing axis A, which is the central axis of rotation of the bearing assembly 4. Although various applications are possible, the bearing assembly 4 provides low-friction (i.e., rolling) support for a first component (e.g., a rotating shaft) within a second component (e.g., a fixed housing). The inner ring 8 includes a radially inner surface fixed to the first component (not shown), and the outer ring includes a radially outer surface fixed to the second component (not shown). Each of the rolling elements 12 defines a rolling surface 16 that contacts the raceway surfaces of the inner and outer rings, respectively. Figure 4 The raceway surface 20 of the inner ring 8 is... Figure 2 The example shown is illustrated. In the illustrated embodiment, the rolling element 12 has a tapered rolling surface 16, but other structures (i.e., cylindrical) are optional. Figure 1 As shown, the cage 24 extends circumferentially about the bearing axis A at a radial position located between the inner ring 8 and the outer ring, such that the cage 24 and the plurality of rolling elements 12 occupy a common radial position. The cage 24 includes a pair of opposing axial rings 28, 32 and a plurality of bridge portions 36 extending generally axially between the two axial rings 28, 32. In some embodiments, one or both axial rings 28, 32 may include flanges (e.g., bent or rolled portions). Roller receptacles 40 are defined between each pair of adjacent bridge portions 36, and thus the cage 24 maintains a predetermined interval between adjacent pairs of rolling elements 12 by positioning the rolling elements 12 within the roller receptacles 40. Figure 6 ).
[0019] One or both of the inner and outer rings may include one or two ribs to retain the rolling element 12 therein. For example, as Figure 2 As shown, the inner ring 8 includes two ribs 44, 46 that extend radially outward beyond the raceway surface 20 to overlap with the axial end faces 48 of a plurality of rolling elements 12 at the two axial ends of the bearing assembly 4. The first rib 44 is referred to as the large rib because it is located at the larger diameter end of the bearing assembly 4. The second rib 46 is referred to as the small rib because it is located at the smaller diameter end of the bearing assembly 4. Those skilled in the art will recognize that various different rib configurations are optional. Regardless of the presence of the rib-roller interface, there is a possibility of wear (e.g., metal-to-metal) when the bearing assembly 4 is in operation and the rolling elements 12 travel circumferentially relative to the inner and outer rings. The interface between the large rib 44 and the rolling elements 12 experiences both rolling and sliding motions. The traction force generated at the rib-roller interface due to the combination of rolling and sliding motions can cause a deflection angle θ on the rolling elements 12 relative to the vertex center A of the geometry of the rolling elements 12 and the raceway 20. Figure 2A misalignment angle θ of the rolling element 12 can lead to a lack of lubrication at the interface between the large rib 44 and the rolling element 12, thereby significantly increasing the friction associated with the interface. Conventional applications of tapered roller bearings typically operate under conditions where the effect of the rolling element 12 misalignment is not a concern. In high-speed operation, such as shaft positions in electric vehicle powertrains, the required rotational speeds for the bearing assembly can exceed 15,000 RPM. At high rotational speeds, the traction force at the rib-roller interface can be large enough to cause the rolling element 12 to misalign, resulting in a lack of lubrication of the rolling element 12 and damage to the bearing assembly 4. However, the cage 24 according to this disclosure is provided with geometry to counteract the misalignment of the rolling element 12, as described in further detail below.
[0020] Figure 3 A rolling element 12 within a roller housing 40 of a bearing assembly cage 24 is shown. The roller housing 40 is divided into four quadrants Q1, Q2, Q3, and Q4 by an axis B equidistant and parallel to the cage bridge 36 and an axis C equidistant and parallel to the opposing axial rings 28, 32 of the cage 24. The two axes B and C intersect at a point on the rolling element 12 about which the rolling element 12 rotates during skew. Within each of the four quadrants Q1, Q2, Q3, and Q4 is a Rayleigh step array 52 disposed on the inner surface 56 of the bridge 36 facing and selectively interacting with the rolling element 12. The Rayleigh step array 52 is spaced apart from the axis C. In other words, the cage bridge 36 has a Rayleigh step array 52 at each end of the inner surface 56 and close to the corresponding opposing axial rings 28, 32.
[0021] The Rayleigh step array 52 is a grouping of one or more Rayleigh step geometries positioned together and oriented such that they are simultaneously activated. In this disclosure, the Rayleigh step geometry follows the general shape of a conventional Rayleigh step and is used to generate hydrodynamic force F on the rolling element 12. The dimensions of each feature of the Rayleigh step geometry can be adjusted for a specific application. In the illustrated embodiment, each quadrant Q1, Q2, Q3, Q4 has a Rayleigh step array 52, and each array contains multiple Rayleigh step geometries. Figure 6A perspective view of a bearing cage 24 including a Rayleigh step array 52 on the cage bridge portion 36 is shown. In other embodiments, some quadrants may be provided without the Rayleigh step array, or the Rayleigh step array 52 may contain different numbers or arrangements of step geometries. For example, a bearing assembly that will rotate in only one direction may have a Rayleigh step array 52 located in only one diagonal quadrant group (e.g., the first and third quadrants Q1, Q3, but not in the second and fourth quadrants Q2, Q4), since the bearing assembly will only need to counteract skew in one direction. Similarly, the roller housing 40 may have a Rayleigh step array in only one quadrant if deemed effective for a suitable application. Within each quadrant containing the Rayleigh step array 52, the step geometry is positioned such that the synthetic hydrodynamic forces generated when the array is activated act effectively on the rolling element 12. The specific location of each Rayleigh step in the array 52 may vary based on available manufacturing techniques and the desired direction of the synthetic hydrodynamic forces from the array 52. The illustrated embodiment shows a Rayleigh step array 52 used on a single-row tapered roller bearing assembly. However, the described Rayleigh step array 52 can be used on other bearing assemblies that utilize a cage and contain lubricant between the cage and the rolling element surfaces. For example, cylindrical roller bearing assemblies, multi-row tapered roller bearing assemblies, and multi-row cylindrical roller bearing assemblies can all have cages with Rayleigh step arrays according to aspects of this disclosure.
[0022] Regarding the rolling element 12 disposed within the roller housing 40, the Rayleigh step array 52 is located on the bridge portion 36 at four quadrants Q1', Q2', Q3', and Q4' corresponding to the surface of the rolling element 12. The four rolling element quadrants Q1', Q2', Q3', and Q4' are separated by the rotation center line D of the rolling element 12 and an axis E parallel to and equidistant from the axial end face 48 of the rolling element 12. Each quadrant Q1', Q2', Q3', and Q4' is configured to interface with the Rayleigh step array 52 located in the corresponding quadrants Q1-Q4 of the roller housing 40 to selectively receive the hydrodynamic force F from the Rayleigh step array 52. When the rolling element 12 is not skewed, the roller quadrants Q1'-Q4' are aligned with the roller housing quadrants Q1-Q4, and the gap between the rolling element 12 and the surface 56 having the Rayleigh step array 52 is equal to or greater than a threshold. When the rolling element 12 experiences a skew angle θ (… Figure 5A and 5B When the quadrants Q1-Q4 are misaligned with quadrants Q1'-Q4', and within one diagonal quadrant pair, the gap between the rolling element 12 and the cage surface 56 is below a threshold. Below the threshold, the Rayleigh step array 52 transitions from hydrodynamic dormancy to hydrodynamic activation, as further described below.
[0023] Figure 4 A portion of one of the rolling elements 12 is shown as viewed along the bearing axis A. This view shows that the Rayleigh step array 52 is positioned such that the resulting hydrodynamic force F acts approximately tangentially to the raceway 20 at the roller centerline D. In the illustrated embodiment, the tangential component of the hydrodynamic force F generated by the Rayleigh steps 52 is responsible for counteracting rolling element skew.
[0024] The bearing assembly 4 of this disclosure uses a running lubricant. Conventionally, lubricants are used within bearing assemblies to limit operational frictional forces. The lubricant in the bearing assembly 4 of this disclosure also acts as a working fluid, interacting with the Rayleigh step array 52, where a hydrodynamic force F is generated in response to the skewness of the rolling elements. The Rayleigh step array 52 described herein is a passive geometry included on the bridge portion 36 of the cage 24, which interacts with the lubricant and a second surface (i.e., the rolling element surface 16) to generate the hydrodynamic force F. The presence of the hydrodynamic force F depends on the lubricant disposed between the rolling element 12 and the cage bridge portion surface 56 containing the Rayleigh step array 52, and the relative velocity between the rolling element 12 and the Rayleigh step array 52. An increased relative velocity between the rolling element 12 and the Rayleigh step array 52 results in a larger hydrodynamic force F.
[0025] In operation, a Rayleigh step array 52 located within each roller housing 40 serves to prevent the rolling element 12 within the housing 40 from experiencing prolonged skewness. Furthermore, the Rayleigh step array 52 is configured to be activated by roller skewness, and once activated, the skewness is counteracted by the hydrodynamic force generated in the lubricant at the Rayleigh step array 52. Figures 5A-5B Two possible skew angles θ and θ' of the rolling element 12 are schematically shown. A third rolling element position corresponds to a zero skew angle and is not shown. The skew angles θ and θ' of the rolling element 12 are determined based on the rotation direction of the bearing assembly 4. The relative motion between the Rayleigh step array 52 and the rolling element 12 in only one direction generates the hydrodynamic force F. To compensate for the two potential directions of the skew angle (i.e., angles θ and θ'), diagonally opposite Rayleigh step arrays 52 have the same geometric step orientation, while adjacent Rayleigh step arrays 52 have opposite geometric step orientations. Therefore, two adjacent Rayleigh step arrays 52 cannot be activated simultaneously—this would simply result in the cancellation of the hydrodynamic force F and the skew angles θ and θ' would not be compensated. With a first skew angle θ ( Figure 5AThe rolling element 12 activates the Rayleigh step arrays 52 in the second and fourth quadrants Q2 and Q4, while deactivating the Rayleigh step arrays 52 in the first and third quadrants Q1 and Q3. The hydrodynamic F from the Rayleigh step arrays 52 in the second and fourth quadrants combines to generate a force couple acting on the rolling element 12 to counteract the skew angle θ. The activated Rayleigh step arrays 52 can reduce the skew angle to an acceptable amount or completely eliminate the skew angle θ. If the rotation direction of the bearing assembly 4 is reversed, causing the rolling element 12 to experience a skew angle θ' ( Figure 5B If the rolling element 12 experiences a small skew or no skew, the Rayleigh step arrays 52 in the second and fourth quadrants Q2 and Q4 remain deactivated, while the Rayleigh step arrays 52 in the first and third quadrants Q1 and Q3 remain activated. If the rolling element 12 experiences a small skew or no skew, the Rayleigh step arrays 52 in all four quadrants Q1, Q2, Q3, and Q4 simply remain deactivated, and the bridging portion 36 continues to function in the conventional manner to maintain the spacing of the rolling elements 12. The hydrodynamic force F generated by the Rayleigh step arrays 52 is a function of the relative velocity between the rolling elements 12 and the Rayleigh step arrays 52. As the relative velocity increases, the Rayleigh step arrays 52 generate a larger hydrodynamic force F due to the greater rotational speed of the bearing assembly 4. This effect allows the Rayleigh step arrays 52 to compensate for different degrees of skew of the rolling elements based on the rotational speed of the bearing assembly 4. A bearing assembly with a high rotational speed will cause a greater skew on the rolling element 12. At the same time, a higher rotational speed will generate a greater hydrodynamic force from the active Rayleigh step arrays 52. Therefore, the design of the cage 24 with at least one Rayleigh step array can make bearing assemblies that were originally unsuitable or unable to be rated for high-speed operation now suitable or rated for high-speed operation. One such example is the use of tapered rolling element bearings in electric vehicle powertrains.
[0026] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention described.
Claims
1. A cage for spacing a plurality of rolling elements in a rolling element bearing assembly containing a working fluid, the cage comprising: First axial end ring; Second axial end ring; A central axis of rotation extends centrally through the first axial end ring and the second axial end ring; as well as Multiple bridge sections extending between the first axial end ring and the second axial end ring; as well as A plurality of roller receptacles are defined between the plurality of bridge portions, the plurality of roller receptacles being circumferentially spaced around the cage, each of the plurality of roller receptacles being configured to receive a rolling element therein. At least one of the plurality of roller receptacles includes a Rayleigh step array configured to selectively generate hydrodynamics within the working fluid in response to an skew angle between the axis of rotation of the rolling element within the roller receptacle and the central axis of rotation.
2. The cage according to claim 1, wherein, The roller receiving portion having the Rayleigh step array includes four quadrants, wherein the roller receiving portion is divided into the four quadrants by an axis equidistant and parallel to the bridge portion and an axis equidistant and parallel to the first axial end ring and the second axial end ring, and wherein each of the four quadrants includes the Rayleigh step array.
3. The cage according to claim 2, wherein, The Rayleigh step arrays in adjacent quadrants have opposite geometric step orientations.
4. The cage according to claim 3, wherein, Each Rayleigh step array comprises multiple different Rayleigh step geometries.
5. The cage according to claim 4, wherein, Each Rayleigh step geometry within the Rayleigh step array has the same geometric step orientation.
6. The cage according to claim 1, wherein, Each of the plurality of roller receptacles includes a Rayleigh step array.
7. A rolling element bearing assembly including a cage according to claim 1, the rolling element bearing assembly further comprising: Inner circle; Outer ring; as well as A plurality of rolling elements are disposed within a plurality of roller receptacles, the plurality of rolling elements being configured to facilitate relative rotation between the inner ring and the outer ring.
8. The rolling element bearing assembly according to claim 7, wherein, The plurality of rolling elements are tapered rolling elements, and wherein the plurality of roller receptacles are tapered roller receptacles.
9. The rolling element bearing assembly according to claim 7, wherein, Each of the plurality of roller receptacles includes a Rayleigh step array.
10. The rolling element bearing assembly according to claim 9, wherein, The Rayleigh step array is configured to generate a first hydrodynamic force on the plurality of rolling elements when the outer ring rotates relative to the inner ring in a first direction, and wherein the Rayleigh step array is configured to generate a second hydrodynamic force on the plurality of rolling elements when the outer ring rotates relative to the inner ring in a second direction opposite to the first direction, the second hydrodynamic force acting in a direction different from the first hydrodynamic force.
11. The rolling element bearing assembly according to claim 10, wherein, The first fluid dynamic acts on the plurality of rolling elements at a location different from that of the second fluid dynamic.
12. A method of operating a rolling element bearing assembly, the method comprising: The system provides an inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and a cage, the cage causing the plurality of rolling elements to be circumferentially spaced around the rolling element bearing assembly, the cage including a plurality of roller receptacles in which the plurality of rolling elements are located, at least one of the plurality of roller receptacles including a Rayleigh step array; A relative rotation is applied between the outer ring and the inner ring to position the plurality of rolling elements in rolling contact with the outer ring and the inner ring, the rotation applying a deflection to at least one of the plurality of rolling elements; as well as In response to the skewing of at least one of the plurality of rolling elements, the Rayleigh step array generates hydrodynamic forces on at least one of the plurality of rolling elements to counteract the skewing.
13. The method according to claim 12, wherein, Each of the plurality of roller receptacles includes a Rayleigh step array, each of the Rayleigh step arrays generating anti-skew hydrodynamics on the plurality of rolling elements in response to skewness of the plurality of rolling elements.
14. The method according to claim 12, wherein, The outer ring includes ribs configured to secure the plurality of rolling elements between the outer ring and the inner ring, the ribs applying the skew to the plurality of rolling elements during rotation.