Axial and radially controlled support components 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, the radially outer surface 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, wherein the sleeve includes a radially inwardly extending tab disposed between adjacent components of the support assembly.

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, and U.S. Provisional Patent Application No. 63 / 751,341, filed January 30, 2025, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This application relates to vehicle steering systems, and more particularly to an axially and radially controlled support 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 assembly can be in direct contact with the rack or the ball nut that electromechanically actuates the rack's movement. For example, some ball nut support assemblies include an isolating mechanism used in REPS systems. The ball nut support assembly requires an isolator that is constrained within a gland on the outer race of the ball nut bearing. The isolating gland space is defined by features on several different components, including the rack housing, the bearing outer race, and retaining components such as threaded retainers or combinations of washers and snap rings.

[0007] In the mounting configuration, two separate glands of equal volume are formed on the axially opposite sides of the flange on the outer bearing race. Isolators (two per REPS system) are assembled into each gland and have a volume associated with their geometry. The net build (static) axial compression height and / or width of each isolator gland is the result of the superposition of the housing bore depth and the bearing outer race flange thickness. As the temperature of the environment in which the REPS system resides changes, the components of the REPS system also change. These temperature variations cause dimensional changes in the components based on the coefficients of thermal expansion / contraction of the materials used in each component. Since the housing is aluminum and the bearing outer race is steel, their coefficients of thermal expansion / contraction are different. Due to these different coefficients, the net build (static) axial compression height and / or width of each isolator gland varies with ambient temperature. These variations in the axial height and / or width of the isolator gland cause different amounts of compression / preload / central stiffness in the isolator design, and thus result in different performance characteristics. Summary of the Invention

[0008] 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 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 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, wherein the sleeve includes a radially inwardly extending tab disposed between adjacent components of the support assembly.

[0009] According to another aspect of this disclosure, a support assembly disposed within a housing of a vehicle steering system includes an inner race. The support assembly also includes an outer race having a radially outer surface disposed adjacent to an inner wall of a 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 radially outer surface of the outer race and the inner wall of the rack housing, wherein the sleeve includes radially inwardly extending tabs disposed between adjacent components of the support assembly.

[0010] These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings. Attached Figure Description

[0011] 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.

[0012] Figure 2 This is a front view of the rack assembly of a vehicle's steering system.

[0013] Figure 3 This is a cross-sectional view of a support assembly for a rack assembly according to one aspect of this disclosure.

[0014] 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

[0015] 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.

[0016] 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 solutions. The axially controlled support assembly disclosed herein can be beneficial to several types of vehicle steering systems. For example, the axially 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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 a position is shown in... Figure 2 The character A is used to refer to it.

[0022] 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. However, in other embodiments, the support assembly is in direct contact with the linear translation member 40.

[0023] 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.

[0024] 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 to directly contact the intermediate component (i.e., the sleeve 150) located between the outer race 104 and the rack housing 50. The outer race flange and sleeve can be designed as a clearance fit or an interference fit. In the clearance fit state, the bearing can move radially within the bore, allowing contact to occur between the bearing flange and the sleeve 150. The flange 114 provides a pair of contact areas along the radially outer surface of the outer race 104. Specifically, the first contact area 116 extends from the first axial end 110 of the outer race 104 to the first axial edge 118 of the flange 114, and the second contact area 120 extends from the second axial end 112 of the outer race 104 to the opposite, second axial edge 122 of the flange 114.

[0025] 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.

[0026] A first axial edge 118 of the flange 114 of the outer race 104 and a threaded retainer 128 define a first axial space. A second axial edge 122 and a 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 the entire space is difficult to fill in the desired manner due to design tolerances and manufacturing processes. The support assembly 100 disclosed herein provides excellent steering feel and thermal performance.

[0027] 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.

[0028] exist Figure 3 In this embodiment, the outer diameter of the sleeve 150 is press-fitted (i.e., interference fit) 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 the outer race 104 to move relative to the sleeve 150.

[0029] In some embodiments, the sleeve 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] According to any of the embodiments disclosed herein, sleeve 150 includes a tab 160 extending radially inward to abut one of isolators 130, 132. In some embodiments, for example Figure 3 In one embodiment, the tab 160 of the sleeve 150 is located at the second axial sleeve end 154. In this embodiment, the tab 160 is positioned between the second isolator 132 and the second shoulder 126 of the rack housing 50. However, in other embodiments, the tab 160 of the sleeve 150 may be located at other axial positions along the sleeve 150, such as... Figure 4 As shown. In Figure 4 In the middle, the tab 160 is located between the first isolator 130 and the first axial edge 118 of the flange 114.

[0032] The thickness of tab 160 is added to the dimensional stack. Because the plastic material of sleeve 150 has a different coefficient of thermal expansion / contraction than both housing 50 and bearing outer race 104, it can accommodate dimensional changes in these components at different temperatures, which causes a constant amount of axial compression on isolators 130, 132 at any temperature. The thickness and material can be adjusted to appropriately accommodate dimensional changes in housing 50 and bearing outer race 104 due to temperature variations.

[0033] In some embodiments, plastic overmold washers may be added to the opposite sides of the axially stacked spacers adjacent to the retainer, for the same purpose as tabs 160 on plastic sleeves 150 within rack housing 50.

[0034] The sleeve 150 can be overmolded within the housing 50 (and / or retainer) and machined using forming tools to reduce the amount of dimensional tolerances of the precision-machined overmolded sleeve.

[0035] In some embodiments, to increase the fill percentage of the isolator gland, partitioned washers are placed between adjacent components to reduce the aforementioned NVH issues associated with unfilled axial space in the gland region. To adjust the axial compression on the isolator, washers of the correct thickness are added to the rack housing bore before the support assembly 100 and the threaded retainer 128 are installed into the rack housing 50. To determine the required washer thickness, two measurements of the actual component dimensions are performed. First, the axial depth of the housing bore is measured. This axial distance is within... Figure 3 L1 is used to denote this distance, and since the tab 160 is included within the axial stacking path, this axial distance extends from the first shoulder 124 to the inner edge of the sleeve tab 160. Figure 4 In this embodiment, the axial distance is to the second shoulder 126. Next, the axial distance of the bearing outer race flange is measured. This axial distance is... Figure 3 and Figure 4 L2 is used to denote this value, and it is derived from the first axial edge of the flange 114 of the outer bearing ring 104 to the second axial edge of the flange 114. Figure 4 In this context, the L2 dimension includes the thickness of the tab 160 on the left side of the bearing flange 114. The results of these two measurements are compared with a table or other database to see which predetermined "area" corresponds to the gasket thickness "area" to achieve the desired amount of isolation gland fill percentage.

[0036] In some embodiments, the reduced tolerance, combined with the “zone” gasket, causes a smaller change in the isolation gland fill percentage, thereby providing an increase in the nominal stacked gland fill percentage while avoiding gland fill exceeding 100% in stacked conditions.

[0037] 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, wherein the sleeve includes radially inwardly extending tabs disposed between adjacent components of the support assembly.

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 of claim 2, further comprising a washer adjacent to one of the first isolator and the second isolator.

6. The vehicle steering system according to claim 5, wherein, The axial thickness of the washer is selected based on a first measurement and a second measurement, wherein the first measurement is the actual axial length obtained from a first shoulder and a second shoulder of the inner wall of the rack housing and / or a radially extending tab of the sleeve, and wherein the second measurement is the actual axial length obtained from the first axial edge of the flange to the second axial edge of the flange.

7. The vehicle steering system according to claim 2, wherein, The radially inwardly extending tab is disposed between the second isolator and the shoulder of the rack housing.

8. The vehicle steering system according to claim 2, wherein, The radially inwardly extending tab is disposed between the first isolator and the first axial edge of the flange of the outer race.

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

10. The vehicle steering system according to claim 1, wherein, The sleeve is press-fitted to the inner wall of the rack housing.

11. 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 radially outer surface of the outer race and the inner wall of the rack housing, wherein the sleeve includes radially inwardly extending tabs disposed between adjacent components of the support assembly.

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

13. The support assembly according to claim 11, wherein, The radially inwardly extending tab is disposed between the second isolator and the shoulder of the rack housing.

14. The support assembly according to claim 11, wherein, The radially inwardly extending tab is disposed between the first isolator and the first axial edge of the flange of the outer race.

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

16. The support assembly according to claim 11, wherein, The sleeve is press-fitted to the inner wall of the rack housing.

Images