Radially controlled support assembly for rack systems in vehicle steering systems

Abstract

A vehicle steering system includes a rack housing. The vehicle steering system also includes a linear translation member disposed within the rack housing. The vehicle steering system further includes a support assembly. The support assembly includes an inner race. The support assembly also includes an outer race having a radially outer surface disposed adjacent to the inner wall of the rack housing, extending from a first axial end to a second axial end, and having a radially outwardly extending flange. The support assembly also includes a sleeve radially disposed between the radially outer surface of the outer race and the inner wall of the rack housing.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 726,739, filed December 2, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This application relates to vehicle steering systems, and more particularly to a radially controlled bearing assembly for a rack system in a vehicle steering system. Background Technology

[0004] Vehicle steering systems typically include a rack extending between tie rods to control the position of the vehicle's wheels, thereby performing steering operations. The rack is housed within a rack housing. One or more support assemblies may be required at one or more locations along the rack to maintain its desired position and performance.

[0005] Various electric power steering (EPS) systems have been developed to assist operators in steering vehicles. One type of EPS system is called rack and pinion electric power steering (REPS), which utilizes an electric motor that drives a ball nut and a rack. The rack teeth engage with a pinion that complements a drive feature that rotates in response to rotation of a portion of the steering column caused by the operator, wherein the drive feature provides steering input to the rack. The drive feature can be integrated with the steering column (i.e., a single-pinion electric power steering system), or it can be, for example, a drive pinion (i.e., a dual-pinion electric power steering system).

[0006] The aforementioned support assemblies can directly contact the rack or the ball nut that electromechanically actuates the rack's movement. For example, some ball nut support assemblies include isolation mechanisms used in REPS systems. Some support assemblies use a small-clearance sliding fit between the bearing race flange and the housing bore to constrain the elastomeric isolators within their glands, thus preventing elastomeric extrusion; however, they allow axial movement of the bearing within the housing during high axial rack load events. This axial movement is controlled by the compression and decompression of the elastomeric isolators within their respective glands. When a radial load is applied, the bearing race flange can contact the housing bore because the isolators do not completely restrict the bearing's radial travel. This metal-to-metal contact causes NVH problems, especially when the REPS system is heated / cooled, causing dimensional changes in the sliding fit between the bearing race flange and the housing bore due to differences in the coefficients of thermal expansion of the components. This ball nut bearing isolation design may not meet some OEMs' NVH performance requirements associated with temperature profile overlay. Summary of the Invention

[0007] According to one aspect of this disclosure, a vehicle steering system includes a rack housing. The vehicle steering system also includes a linear translational member disposed within the rack housing. The vehicle steering system further includes a support assembly. The support assembly includes an inner race. The support assembly also includes an outer race having a radially outer surface disposed adjacent to the inner wall of the rack housing, extending from a first axial end to a second axial end, and having a radially outwardly extending flange. The support assembly also includes a sleeve radially disposed between the radially outer surface of the outer race and the inner wall of the rack housing.

[0008] According to another aspect of this disclosure, a support assembly disposed within a housing of a vehicle steering system. The support assembly includes an inner race. The support assembly also includes an outer race having a radially outer surface disposed adjacent to the inner wall of the rack housing, extending from a first axial end to a second axial end, and having a radially outwardly extending flange. The support assembly also includes a first isolator adjacent to a first axial edge of the flange. The support assembly also includes a second isolator adjacent to a second axial edge of the flange, wherein the first and second isolators are formed of a deformable material. The support assembly also includes a sleeve radially disposed between the flange of the outer race and the inner wall of the rack housing.

[0009] These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings. Attached Figure Description

[0010] The subject matter of this disclosure is specifically pointed out and expressly claimed in the claims at the end of this specification. The foregoing and other features and advantages of this disclosure will be apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein: Figure 1 The diagram illustrates the vehicle's steering system.

[0011] Figure 2 This is a front view of the rack assembly of a vehicle's steering system.

[0012] Figure 3 This is a cross-sectional view of a support assembly for a rack assembly according to one aspect of this disclosure.

[0013] Figure 4 This is a cross-sectional view of a support assembly for a rack assembly according to another aspect of this disclosure. Detailed Implementation

[0014] The present disclosure will now be described with reference to the accompanying drawings, in which specific embodiments will be illustrated, and not to be construed as limiting. It should be understood that the disclosed embodiments are merely illustrative, and the disclosure may be embodied in various alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but are merely a representative basis for teaching those skilled in the art to employ the disclosure in various ways.

[0015] The embodiments described herein are used in conjunction with steering components of vehicles such as automobiles, trucks, SUVs, crossovers, minivans, ships, aircraft, all-terrain vehicles, SUVs, or other suitable vehicles including various steering system options. The radially controlled support assembly disclosed herein can be beneficial to several types of vehicle steering systems. For example, the radially controlled support assembly can be used in any type of steering system to control the position and movement of the rack itself. Furthermore, the support assembly can be incorporated into any type of electric power steering (EPS) system, such as systems with rack-and-pinion electric steering (REPS), column-and-pinion electric steering (CEPS), and pinion-and-pinion electric steering (PEPS). Additionally, the support assembly can be incorporated into steer-by-wire systems where there is no continuous physical connection between the steering wheel and the rack, including systems without a pinion connected to the rack to counteract the forces caused by actuation of the electric system.

[0016] At a basic level, a rack is any linear translational component, which may also be referred to as a rack or ball screw, for example. In some embodiments, the support assembly is the ball nut itself and is rotated to actuate the translation of the linear translational component. In this embodiment, the inner race of the support assembly is in threaded contact with the ball screw. In other embodiments, the inner race is in contact with the outer diameter of a separate ball nut that performs the translation of the ball screw.

[0017] First refer to Figure 1 The diagram 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 allowing both driver-interface and autonomous steering. The steering system may include an input device 22, such as a steering wheel, through which the driver mechanically provides 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 for steering systems in which the output assembly 28 is operatively connected to an actuator 34 coupled to a linear translation member 40 (e.g., steer-by-wire, autonomous system, etc.). The output assembly 28 has a wired electrical communication 36 with the actuator 34. The actuator 34 drives the linear translation member 40 to provide steering control of the vehicle.

[0018] The linear translation component 40 is any component having a generally cylindrical cross-section along at least a portion of its length and being driven in a substantially linear manner to achieve adjustment of the vehicle wheel 49. In some embodiments, the linear translation component 40 is a ball screw. In other embodiments, the linear translation component 40 is a lead screw. The foregoing examples do not limit the linear translation component 40.

[0019] Reference Figure 2 The rack housing 50 is shown having a pair of sealing members 52, such as sealing sleeves, operatively coupled to the ends of the rack housing 50. The rack housing 50 houses a linear translation member 40. A pair of levers 53 are shown located at the ends of the linear translation member 40 and extending from the sealing members 52. A pinion 54 is positioned to extend through an opening in the rack housing 50 to contact the linear translation member 40 (not shown) to provide steering input from the vehicle operator.

[0020] The illustrated embodiment is a rack and pinion electric steering (REPS) system, which has an electric motor 60 that actuates the movement of a linear translation member 40 to assist the vehicle operator in steering operations. However, as mentioned above, the support assembly disclosed herein can be used in several different types of steering systems. Also as mentioned above, the position of the support assembly can vary depending on the specific type of steering system in which it is used. An example of one position is shown in... Figure 2 The character A is used to refer to it.

[0021] Figure 3 This is a cross-sectional view of the support assembly 100 disclosed herein. The support assembly 100 is located at the inner wall 102 of the rack housing 50. The support assembly 100 is located within the internal space defined by the rack housing 50 and between the rack housing 50 and the linear translation member 40 (e.g., rack, ball screw, lead screw, etc.). As described above, in some embodiments, the support assembly 100 is the ball nut itself and is rotated to actuate the translation of the linear translation member, while in other embodiments, the inner race contacts the outer diameter of the individual ball nut that performs the translation of the ball screw. In other embodiments, the support assembly is in direct contact with the linear translation member 40.

[0022] The support assembly 100 includes an outer race 104 and an inner race 106. The outer race 104 and the inner race 106 define space therein for the movement of the balls 108 supporting the assembly 100. In the illustrated embodiment, a double-row bearing is shown to accommodate two rows of balls 108. However, it should be understood that more or fewer rows may be present in other embodiments.

[0023] The outer race 104 extends from the first axial end 110 (in Figure 3 (in the left direction) extends to the second axial end 112 (in Figure 3 (To the right). The flange 114 extends radially outward along the outer race 104, which contacts an intermediate component located between the outer race 104 and the rack housing 50. The flange 114 provides a pair of contact areas along the radially outer surface of the outer race 104. Specifically, a first contact area 116 extends from a first axial end 110 of the outer race 104 to a first axial edge 118 of the flange 114, and a second contact area 120 extends from a second axial end 112 of the outer race 104 to the opposite, second axial edge 122 of the flange 114.

[0024] As shown in the figure, the outer race 104 of the support assembly 100 is positioned axially on the inner wall 102 of the rack housing. The flange 114 of the outer race 104 is located between the first shoulder 124 and the second shoulder 126 of the inner wall 102 of the rack housing 50. The first shoulder 124 (in Figure 3 A threaded retainer 128 is positioned to accommodate the axial position of the fixed support assembly 100 (on the left side). A first shoulder 124 can also provide a hard stop for the threaded retainer 128. A second shoulder 126 (on the left side) of the rack housing inner wall 102... Figure 3 (to the right) is located on the other side of the flange 114 of the outer seat ring 104.

[0025] The first axial edge 118 of the flange 114 of the outer race 104 and the threaded retainer 128 define a first axial space. The second axial edge 122 and the second shoulder 126 of the flange 114 of the outer race 104 define a second axial space. A first isolator 130 is positioned within the first axial space, and a second isolator 132 is positioned within the second axial space. Each isolator 130, 132 is formed of a deformable material, such as an elastomer in some embodiments. The isolators 130, 132 fill a portion of the entire axial space, but due to design tolerances and manufacturing processes, the entire space is difficult to fill in the desired manner. The support assembly 100 disclosed herein provides excellent steering feel and thermal performance. Even tightening tolerances on some or all dimensional specifications related to the isolator gland fill percentage will leave some axial space, causing undesirable clicking sounds (i.e., NVH problems) in the components.

[0026] The sleeve 150 is positioned between the outer diameter of the flange 114 of the outer race 104 and the inner wall 102 of the rack housing. Furthermore, in Figure 3 In the illustrated embodiment, sleeve 150 is radially positioned between the inner wall 102 of rack housing 50 and the first isolator 130 and the second isolator 132. Specifically, sleeve 150 extends axially from the first axial sleeve end 152 to the second axial sleeve end 154, wherein sleeve 150 axially overlaps the entire outer diameter of the outer race flange and at least a portion of the first isolator 130 and the second isolator 132. In the illustrated embodiment, the first axial sleeve end 152 and the threaded retainer 128 define a small gap between them, while the second end of the sleeve contacts the second shoulder of the rack housing. It is contemplated that in other embodiments, the first axial sleeve end 152 may directly contact the threaded retainer 128. In any embodiment disclosed herein, a chamfer 170 may be present radially outward along the second axial sleeve end 154.

[0027] exist Figure 3 In this embodiment, the outer diameter of the sleeve 150 is press-fitted to 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 race 104 are positioned in a small-clearance sliding fit assembly to allow movement of the outer race 104 relative to the sleeve 150. The bearing outer race 104 and the inner diameter of the sleeve can be a sliding fit or an interference fit.

[0028] Another aspect of this disclosure is Figure 4 As shown in the diagram, the sleeve 150 is radially disposed between the outer diameter of the flange 114 and the inner diameter of the rack housing 50, as... Figure 3The embodiment, however, has a smaller axial coverage area of ​​the sleeve 150 within the gland than... Figure 3 The axial coverage area of ​​the embodiment. Specifically, the sleeve 150 is not radially disposed between the first isolator 130 and the second isolator 132 and the inner diameter of the rack housing. The first axial end 152 of the sleeve 150 abuts the axial surface of the first isolator 130, and the second axial end 154 of the sleeve 150 abuts the axial surface of the second isolator 132. In other words, the first isolator 130 is axially located between the threaded retainer 128 and the sleeve 150, and the second isolator 132 is axially located between the sleeve 150 and the second shoulder 126 of the inner wall 102 of the rack housing 50.

[0029] In some embodiments, the sleeve 150 disclosed herein is made of plastic, but it should be understood that other suitable materials with a high coefficient of thermal expansion may be used.

[0030] In the embodiments disclosed herein, sleeve 150 is mounted into the rack housing isolating bearing bore to serve as a radial damper at the interface between the housing bore surface (i.e., inner wall 102) and the bearing outer race flange 114. Sleeve 150 also serves as a thermal expansion / contraction compensator at the interface between the bearing outer race 104 and the inner diameter of the mounted sleeve. Sleeve 150 also serves as a restraining sealing wall for isolators 130, 132. Sleeve 150 further serves as a thermal expansion / contraction compensator to minimize the extrusion gap size of the elastomeric isolator within the temperature range necessary for isolator durability.

[0031] While this disclosure has been described in detail with reference to only a limited number of embodiments, it should be readily understood that this disclosure is not limited to these disclosed embodiments. Rather, this disclosure can be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not previously described but commensurate with the scope of this disclosure. Furthermore, although various embodiments of this disclosure have been described, it should be understood that aspects of this disclosure may include only some embodiments or combinations of various embodiments described. Therefore, this disclosure should not be considered as limited to the foregoing description.

Claims

1. A vehicle steering system, comprising: rack housing; A linear translation component is disposed within the rack housing; as well as Support assembly, including: Inner seat ring; The outer race has a radially outer surface disposed adjacent to the 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 radially outwardly extending flange; and A sleeve is radially disposed between the radially outer surface of the outer race and the inner wall of the rack housing.

2. The vehicle steering system according to claim 1, further comprising: The first isolator is located adjacent to the first axial edge of the flange; as well as The second isolator is located adjacent to the second axial edge of the flange.

3. The vehicle steering system according to claim 2, wherein, The first isolator and the second isolator are formed of deformable material.

4. The vehicle steering system according to claim 3, wherein, The first isolator and the second isolator are formed of an elastomer.

5. The vehicle steering system according to claim 1, wherein, The sleeve is made of plastic.

6. The vehicle steering system according to claim 2, wherein, The sleeve is located radially between the first isolator 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 isolator and the inner wall of the rack housing.

7. The vehicle steering system according to claim 6, wherein, The sleeve is press-fitted into the inner wall of the rack housing.

8. The vehicle steering system according to claim 2, wherein, The sleeve is axially located between the first isolator and the second isolator, wherein the sleeve is radially located between the flange and the inner surface of the rack housing.

9. The vehicle steering system according to claim 8, wherein, The sleeve is press-fitted to the radial outer surface of the flange of the outer bearing ring.

10. A support assembly disposed within a housing of a vehicle steering system, the support assembly comprising: Inner seat ring; The outer race has a radially outer surface disposed adjacent to the inner wall of the rack housing, the radially outer surface extending from a first axial end to a second axial end, and the radially outer surface having a radially outwardly extending flange; The first isolator is located adjacent to the first axial edge of the flange; A second isolator, adjacent to the second axial edge of the flange, wherein the first and second isolators are formed of a deformable material; and A sleeve is radially disposed between the flange of the outer race and the inner wall of the rack housing.

11. The support assembly according to claim 10, wherein, The first isolator and the second isolator are formed of an elastomer.

12. The support assembly according to claim 11, wherein, The sleeve is made of plastic.

13. The vehicle steering system according to claim 10, wherein, The sleeve is located radially between the first isolator 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 isolator and the inner wall of the rack housing.

14. The vehicle steering system according to claim 13, wherein, The sleeve is press-fitted into the inner wall of the rack housing.

15. The vehicle steering system according to claim 10, wherein, The sleeve is axially located between the first isolator and the second isolator, wherein the sleeve is radially located between the flange and the inner surface of the rack housing.

16. The vehicle steering system according to claim 15, wherein, The sleeve is press-fitted to the radial outer surface of the flange of the outer bearing ring.

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