Radially regulated bearing arrangement for a rack and pinion system of a vehicle steering system

Abstract

A vehicle steering system comprises a rack housing. The vehicle steering system also comprises a linear translation component arranged within the rack housing. The vehicle steering system further comprises a bearing assembly. The bearing assembly comprises an inner ring. The bearing assembly also comprises an outer ring having a radially outer surface located adjacent to an inner wall of the rack housing, the radially outer surface extending from a first axial end to a second axial end, the radially outer surface having a flange extending radially outward. The bearing assembly further comprises a sleeve located radially between the radially outer surface of the outer ring and the inner wall of the rack housing.

Description

CROSS-REFERENCE TO THE RELATED REGISTRATION

[0001] This application claims the benefits of priority of provisional US patent application No. 63 / 726,739, filed on December 2, 2024, the disclosure of which is incorporated herein by reference in its entirety. AREA OF INVENTION

[0002] This application relates to vehicle steering systems and in particular to a radially regulated bearing arrangement for a rack and pinion system of a vehicle steering system. BACKGROUND OF THE REVELATION

[0003] Vehicle steering systems typically include a rack and pinion extending between tie rods to control the position of the vehicle's road wheels and thus execute steering maneuvers. The rack is housed within a rack housing. One or more bearing assemblies may be required at one or more points along the rack to maintain the desired position and performance of the rack.

[0004] Several electric power steering (EPS) systems have been developed to assist an operator in steering a vehicle. One type of EPS system is called a rack and pinion electric power steering (REPS) system, which uses an electric motor to drive a ball nut and rack. The rack teeth mesh with a pinion that complements a drive feature. This drive feature rotates in response to the operator rotating a section of the steering column, providing steering input at the rack. The drive feature may be integrated into the steering column (i.e., a single-pinion electric power steering system) or it may be a drive pinion (i.e., a double-pinion electric power steering system).

[0005] The bearing assembly described above can be in direct contact with the rack or with a ball nut that electromechanically actuates the rack's movement. For example, some ball nut bearing assemblies incorporate an isolation mechanism, as used in REPS systems. Some bearing assemblies employ low-clearance sliding fits between the outer ring flange and the housing bore to confine elastomer isolators within their bushings—thus preventing elastomer extrusion—but also to allow the bearing to move axially within the housing during high axial rack loading events. This axial movement is regulated by compression and decompression of the elastomer isolators within their respective bushings.The outer ring flange can contact the housing bore when a radial load is applied because the insulators do not completely restrict the bearing travel in the radial direction. This metal-to-metal contact causes NVH (noise, vibration, and harshness) problems, especially when REPS systems are heated / cooled. The difference in the coefficients of thermal expansion of the components leads to a change in the sliding fit between the outer ring flange and the housing bore. Such ball nut bearing isolation concepts may not meet some OEMs' NVH performance requirements with temperature profile overlay. SUMMARY

[0006] According to one aspect of the disclosure, a vehicle steering system comprises a rack housing. The vehicle steering system also comprises a linear translation component arranged within the rack housing. The vehicle steering system further comprises a bearing arrangement. The bearing arrangement comprises an inner ring. The bearing arrangement also comprises an outer ring having a radially outer surface arranged adjacent to an inner wall of the rack housing, the radially outer surface extending from a first axial end to a second axial end, the radially outer surface having a flange extending radially outward. The bearing arrangement further comprises a sleeve arranged radially between the radially outer surface of the outer ring and the inner wall of the rack housing.

[0007] According to another aspect of the disclosure, a bearing arrangement is arranged within a housing of a vehicle steering system. The bearing arrangement comprises an inner ring. The bearing arrangement also comprises an outer ring with a radially outer surface located adjacent to an inner wall of the rack housing, the radially outer surface extending from a first axial end to a second axial end, the radially outer surface having a flange extending radially outward. The bearing arrangement further comprises a first insulator adjacent to a first axial edge of the flange. The bearing arrangement further comprises a second insulator adjacent to a second axial edge of the flange, the first insulator and the second insulator being formed from a deformable material.The bearing arrangement also includes a sleeve that is arranged radially between the flange of the outer ring and the inner wall of the rack housing.

[0008] These and other advantages and features will become clearer from the following description in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The subject matter of this disclosure is specifically highlighted and clearly claimed in the claims at the end of the description. The foregoing and other features and advantages of this disclosure will become apparent from the following detailed description in conjunction with the accompanying drawings. Fig. Figure 1 schematically illustrates a vehicle steering system. Fig. Figure 2 is a top-down view of a rack and pinion assembly of the vehicle steering system. Fig. Figure 3 is a cross-sectional view of a bearing arrangement for the rack arrangement according to one aspect of the disclosure. Fig. Figure 4 is a cross-sectional view of the bearing arrangement for the rack arrangement according to another aspect of the disclosure. DETAILED DESCRIPTION

[0010] With reference to the figures, which describe the present disclosure with reference to specific embodiments without limiting them, it is understood that the disclosed embodiments merely illustrate the present disclosure, which may be implemented in various and alternative forms. The figures are not necessarily to scale; some features may be enlarged or reduced to show details of certain components. Therefore, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching a person skilled in the art how to use the present disclosure in various ways.

[0011] The embodiments described herein are used in conjunction with a steering assembly of a vehicle, such as a car, truck, sport utility vehicle (SUV), crossover, minivan, personal watercraft, aircraft, all-terrain vehicle, motorhome, or other suitable vehicles, which incorporate various steering system schemes. The radially regulated bearing arrangement disclosed herein can be advantageous for several types of vehicle steering systems. For example, the radially regulated bearing arrangement can be used in any type of steering system to regulate the position and movement of a rack itself. Additionally, the bearing arrangement can be provided in any type of electric power steering system (EPS system), such as rack-and-pinion electric power steering (REPS), column electric power steering (CEPS), and pinion electric power steering (PEPS) systems.Additionally, the bearing arrangement can be provided in steer-by-wire systems without a continuous physical connection between the steering wheel and the rack, including systems without pinions connected to the rack to counteract forces induced by actuation with an electric servo system.

[0012] At a basic level, a rack is any linear translation component, which can also be called a rack or ball screw, for example. In some embodiments, the bearing assembly is a ball nut itself and is rotated to effect the translation of the linear translation component. In such an embodiment, the inner ring of the bearing assembly is in contact with threads of the ball screw. In other embodiments, the inner ring is in contact with the outer diameter of a separate ball nut, which performs the translation of the ball screw.

[0013] Initially referring to Fig. Figure 1 generally illustrates a power steering system 20. The power steering system 20 can be configured as a driver interface steering system, an autonomous driving system, or a system that enables both a driver interface and autonomous steering. The steering system can include an input device 22, such as a steering wheel, wherein a driver can mechanically provide steering input by turning the steering wheel. A steering column 26 extends along an axis from the input device 22 to an output assembly 28. The embodiments disclosed herein are used in steering systems in which the output assembly 28 is operatively connected (e.g., steer-by-wire, autonomous system, etc.) to an actuator 34, which is coupled to a linear translation component 40. The output assembly 28 has a wired electrical connection 36 to the actuator 34.The actuator 34 drives the linear translation component 40 to provide steering control of the vehicle.

[0014] The linear translation component 40 is any component having a generally cylindrical cross-section along at least a portion of its length and is driven in a substantially linear manner to effect an adjustment of vehicle road wheels 49. In some embodiments, the linear translation component 40 is a ball screw. In other embodiments, the linear translation component 40 is a leadscrew. The preceding examples do not restrict the linear translation component 40.

[0015] With reference to Fig. Figure 2 is a rack housing 50 with a pair of sealing components 52, such as sealing sleeves, shown, which are functionally coupled to the ends of the rack housing 50. The rack housing 50 accommodates the linear translation component 40. A pair of tie rods 53 are shown at the ends of the linear translation component 40 and extend from the sealing components 52. A pinion 54 is positioned to extend through an opening in the rack housing 50 so that it is in contact with the linear translation component 40 (not shown) to provide steering inputs from a vehicle operator.

[0016] The illustrated embodiment is an electric rack and pinion power steering system (REPS system) with an electric motor 60 that causes the movement of the linear translation component 40 to assist the vehicle operator in steering maneuvers. However, as described above, the bearing arrangement disclosed here can be used in several different types of steering systems. As also described above, the position of the bearing arrangement can vary depending on the specific type of steering system in which it is used. An example of a position is shown in Fig. 2, labeled with the letter A.

[0017] Fig. Figure 3 is a cross-sectional view of the bearing arrangement 100 disclosed herein. The bearing arrangement 100 is located on an inner wall 102 of the rack housing 50. The bearing arrangement 100 is located within the interior space defined by the rack housing 50 and between the rack housing 50 and the linear translation component 40 (e.g., rack, ball screw, leadscrew, etc.). As described above, in some embodiments the bearing arrangement 100 is itself a ball nut and is rotated to effect translation of the linear translation component, while in other embodiments the inner ring is in contact with the outer diameter of a separate ball nut that performs the translation of the ball screw. In still other embodiments the bearing arrangement is in direct contact with the linear translation component 40.

[0018] The bearing arrangement 100 comprises an outer ring 104 and an inner ring 106. The outer ring 104 and the inner ring 106 define a space within which the balls 108 of the bearing arrangement 100 can move. In the illustrated embodiment, a double-row bearing is shown to accommodate two rows of balls 108. However, it is understood that other embodiments may have more or fewer rows.

[0019] The outer ring 104 extends from a first axial end 110 (in the orientation of Fig. 3 to the left) to a second axial end 112 (in the orientation of Fig. 3 to the right). A flange 114 extends radially outward along the outer ring 104 in contact with an intermediate component located between the outer ring 104 and the rack housing 50. The flange 114 provides a pair of web areas along the radially outer surface of the outer ring 104. Specifically, a first web area 116 extends from the first axial end 110 of the outer ring 104 to a first axial edge 118 of the flange 114, and a second web area 120 extends from the second axial end 112 of the outer ring 104 to an opposite, second axial edge 122 of the flange 114.

[0020] As shown, the outer ring 104 of the bearing assembly 100 is positioned at an axial position on the inner wall 102 of the rack housing. The flange 114 of the outer ring 104 is located between a first shoulder 124 and a second shoulder 126 of the inner wall 102 of the rack housing 50. The first shoulder 124 (in the orientation of Fig. 3 on the left) is positioned to receive a threaded holder 128, which fixes the axial position of the bearing assembly 100. The first shoulder 124 can also provide a hard stop for the threaded holder 128. The second shoulder 126 of the inner wall 102 of the rack housing (in the orientation of Fig. 3 right) is located on the other side of the flange 114 of the outer ring 104.

[0021] The first axial edge 118 of the flange 114 of the outer ring 104 and the threaded holder 128 define a first axial space. The second axial edge 122 of the flange 114 of the outer ring 104 and the second shoulder 126 define a second axial space. A first insulator 130 is positioned within the first axial space, and a second insulator 132 is positioned within the second axial space. Each insulator 130, 132 is formed from a deformable material, such as an elastomer in some embodiments. The insulators 130, 132 fill a portion of the total axial space, but this entire space is difficult to fill in a desired manner due to design tolerances and manufacturing processes. The bearing arrangement 100 disclosed here provides excellent steering feel and thermal behavior.Even tightening tolerances in some or all specification dimensions with respect to the insulation bushing fill percentage leave some axial space, which leads to undesirable component chatter (i.e., NVH problems).

[0022] A sleeve 150 is positioned between the outer diameter of the flange 114 of the outer ring 104 and the inner wall 102 of the rack housing. Additionally, in the illustrated embodiment of Fig. 3. The sleeve 150 is positioned radially between the inner wall 102 of the rack housing 50 and the first and second insulators 130, 132. In particular, the sleeve 150 extends axially from a first axial sleeve end 152 to a second axial sleeve end 154, the sleeve 150 axially overlapping an entirety of the outer diameter of the outer ring flange as well as at least a portion of the first and second insulators 130, 132. In the illustrated embodiment, the first axial sleeve end 152 and the threaded holder 128 define a small gap between them, while the second end of the sleeve is in contact with the second shoulder of the rack housing. It is considered that in other embodiments, the first axial sleeve end 152 is in direct contact with the threaded holder 128. A chamfer 170 can be present in each of the embodiments disclosed herein along the radially outer section of the second axial sleeve end 154.

[0023] The outer diameter of the sleeve 150 is, in the embodiment of Fig. The sleeve is press-fitted onto the inner wall 102 of the rack housing 50. Therefore, the sleeve is fixed in position relative to the rack housing 50. The inner diameter of the sleeve 150 and the outer diameter of the flange 114 of the outer ring 104 are positioned in a sliding fit with minimal clearance to allow the outer ring 104 to move relative to the sleeve 150. The bearing outer ring 104 to the sleeve inner diameter can be a sliding fit or an interference fit.

[0024] Another aspect of the revelation is in Fig. 4 shown. The sleeve 150 is arranged radially between the outer diameter of the flange 114 and the inner diameter of the rack housing 50, as in the embodiment of Fig. 3, but the axial base area of ​​the sleeve 150 inside the bushing is smaller than that of the embodiment of Fig.3. In particular, the sleeve 150 is not arranged radially between the first and second insulators 130, 132 and the inner diameter of the rack housing. The first axial end 152 of the sleeve 150 rests against an axial surface of the first insulator 130, and the second axial end 154 of the sleeve 150 rests against an axial surface of the second insulator 132. In other words, the first insulator 130 is located axially between the threaded holder 128 and the sleeve 150, and the second insulator 132 is located axially between the sleeve 150 and the second shoulder 126 of the inner wall 102 of the rack housing 50.

[0025] In some embodiments, the sleeve 150 disclosed herein is made of plastic, but it is understood that other suitable materials with a high coefficient of thermal expansion may be used.

[0026] In the embodiments disclosed herein, the sleeve 150 is installed in the bearing bore to insulate the rack housing and to act as a radial damper at the interface between the housing bore surface (i.e., the inner wall 102) and the bearing outer ring flange 114. The sleeve 150 also acts as a thermal expansion / contraction compensator at the interface between the bearing outer ring 104 and the inner diameter of the installed sleeve. The sleeve 150 also acts as a limiting bushing wall for the insulators 130 and 132. Furthermore, the sleeve 150 acts as a thermal expansion / contraction compensator to minimize the elastomer insulator extrusion gap size within a temperature range relevant to the insulator's durability.

[0027] Although the present disclosure has been described in detail in connection with only a limited number of embodiments, it is readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to include any number of variations, changes, substitutions, or equivalent arrangements not previously described, but which fall within the scope of the present disclosure. Furthermore, it is understood that, although various embodiments of the present disclosure have been described, aspects of the present disclosure may only encompass some of the described embodiments or combinations of the various embodiments. Accordingly, the present disclosure is not to be considered as limited by the foregoing description. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 726,739

[0001]

Claims

[1] Vehicle steering system, comprising: a rack housing; a linear translation component located inside the rack housing; and a storage arrangement, comprising: an inner ring; an outer ring with a radially outer surface arranged adjacent to an inner wall of the rack housing, the radially outer surface extending from a first axial end to a second axial end, the radially outer surface having a flange extending radially outwards; and a sleeve that is arranged radially between the radially outer surface of the outer ring and the inner wall of the rack housing. [2] Vehicle steering system according to claim 1, further comprising: a first insulator adjacent to a first axial edge of the flange; and a second insulator adjacent to a second axial edge of the flange. [3] Vehicle steering system according to claim 2, wherein the first insulator and the second insulator are formed from a deformable material. [4] Vehicle steering system according to claim 3, wherein the first insulator and the second insulator are formed from an elastomer. [5] Vehicle steering system according to claim 1, wherein the sleeve is made of plastic. [6] Vehicle steering system according to claim 2, wherein the sleeve is located radially between the first insulator and the inner wall of the rack housing, radially between the flange and the inner wall of the rack housing and radially between the second insulator and the inner wall of the rack housing. [7] Vehicle steering system according to claim 6, wherein the sleeve is press-fitted onto the inner wall of the rack housing. [8] Vehicle steering system according to claim 2, wherein the sleeve is located axially between the first insulator and the second insulator, wherein the sleeve is located radially between the flange and the inner surface of the rack housing. [9] Vehicle steering system according to claim 8, wherein the sleeve is press-fitted onto the radially outer surface of the flange of the outer ring. [10] Bearing arrangement arranged within a housing of a vehicle steering system, the bearing arrangement comprising: an inner ring; an outer ring with a radially outer surface arranged adjacent to an inner wall of the rack housing, wherein the radially outer surface extends from a first axial end to a second axial end, wherein the radially outer surface has a flange extending radially outwards; a first insulator adjacent to a first axial edge of the flange; a second insulator adjacent to a second axial edge of the flange, wherein the first insulator and the second insulator are formed from a deformable material; and a sleeve that is arranged radially between the flange of the outer ring and the inner wall of the rack housing. [11] Bearing arrangement according to claim 10, wherein the first insulator and the second insulator are formed from an elastomer. [12] Bearing arrangement according to claim 11, wherein the sleeve is made of plastic. [13] Vehicle steering system according to claim 10, wherein the sleeve is located radially between the first insulator and the inner wall of the rack housing, radially between the flange and the inner wall of the rack housing and radially between the second insulator and the inner wall of the rack housing. [14] Vehicle steering system according to claim 13, wherein the sleeve is press-fitted onto the inner wall of the rack housing. [15] Vehicle steering system according to claim 10, wherein the sleeve is located axially between the first insulator and the second insulator, wherein the sleeve is located radially between the flange and the inner surface of the rack housing. [16] Vehicle steering system according to claim 15, wherein the sleeve is press-fitted onto the radially outer surface of the flange of the outer ring.

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