Improved electric power steering gear arrangement with anti-rotation feature

Abstract

An improved electric power steering gear arrangement having an anti-rotation feature is provided. The steering assembly includes a housing. An inner wall of the cylindrical portion of the housing defines a groove extending in an axial direction, the groove having an inwardly tapering wall. A ball screw disposed in the housing defines a bore in a radial direction. An anti-rotation pin having a tapered end is disposed in the bore, the tapered end corresponding to the inwardly tapered wall. A spring disposed in the bore biases the anti-rotation pin such that the tapered end of the anti-rotation pin engages the groove and limits rotation of the ball screw. A support bushing disposed between the ball screw and the housing is fixedly coupled to the ball screw and defines a through hole between the groove and the bore of the ball screw, the through hole receiving the anti-rotation pin. The support bush absorbs a radial load applied to the ball screw and supports the anti-rotation pin.

Description

Technical Field

[0001] The present disclosure relates to a steering gear arrangement for a vehicle having an anti-rotation feature. Background Art

[0002] Commercial vehicles use electric power steering (EPS). Electric power steering is implemented using an electric steering gear. The electric steering gear utilizes a ball nut to provide linear translation to a ball screw. This linear translation motion of the ball screw turns the tires to steer the vehicle's path. To prevent the ball screw from rotating with the ball nut, an anti-rotation feature engages the gear housing to rotationally secure the ball screw relative to the housing. Current anti-rotation methods include male splines on the ball screw and female splines secured to the gear housing. One such example is a pin extending through a hole in the ball screw that engages an axial groove in the gear housing, allowing it to slide along the axial groove while inhibiting rotation relative to the gear housing. However, conventional methods do not prevent undesirable free rotational movement (known as lash) caused by manufacturing tolerances and normal wear due to use. Summary of the Invention

[0003] Current anti-rotation features allow for a small amount of play, also known as backlash, between the ball screw and the housing of the steering mechanism due to normal wear and manufacturing tolerances.

[0004] In a first aspect, an embodiment of the present disclosure provides an electric steering assembly for a commercial vehicle, comprising: a housing, the housing including a cylindrical portion extending in an axial direction, the inner wall of the cylindrical portion defining a groove and extending in the axial direction, the groove having at least two inwardly tapering walls; a ball screw disposed in the housing and extending in the axial direction, the ball screw defining a hole extending in a radial direction; a ball nut disposed in the housing and surrounding the ball screw, the ball nut being configured to rotate relative to the housing; an anti-rotation pin having a tapered end disposed in the hole, the tapered end having at least two tapered surfaces, each tapered surface corresponding to at least and a plurality of springs disposed in the housing to engage with the guide rails and guide rails and configured to extend the life of the bearing. The plurality of springs are connected to the housing to form a plurality of springs, each of which is connected to a plurality of bearing rails and guide rails. The plurality of springs are connected to the housing to form a plurality of springs. The plurality of springs are connected to the housing to form a plurality of springs.

[0005] According to an embodiment of the first aspect, the inner wall of the cylindrical portion defines a second groove and extends in the axial direction, the second groove having at least two inwardly tapered walls; the ball screw is placed in the housing and extends in the axial direction, and the ball screw defines a second hole extending in the radial direction; a second anti-rotation pin, the second anti-rotation pin has a tapered end placed in the second hole, the tapered end has at least two tapered surfaces, each tapered surface corresponding to a corresponding one of the at least two inwardly tapered walls of the second groove; and a second spring, the second spring is placed in the second hole, and the second spring is configured to bias the second anti-rotation pin toward the second groove in a radially outward direction, so that at least one tapered end of the second anti-rotation pin engages the second groove, thereby limiting the rotation of the ball screw relative to the housing.

[0006] According to an embodiment of the first aspect, the at least two tapered walls of the groove taper inwardly at a first angle.

[0007] According to an embodiment of the first aspect, the at least two tapered surfaces of the tapered end of the anti-rotation pin taper at the first angle to match the taper of the groove.

[0008] According to an embodiment of the first aspect, the ball nut is configured to rotate on the ball screw and engage the threads of the ball screw.

[0009] According to an embodiment of the first aspect, the rotation of the ball nut on the ball screw causes the ball screw to translate axially in a left direction or a right direction based on the rotation direction of the ball nut.

[0010] According to an embodiment of the first aspect, engaging the groove with the anti-rotation pin limits rotation of the ball screw relative to the ball nut.

[0011] According to an embodiment of the first aspect, the support bushing is fixedly coupled to the ball screw using a plurality of bolts evenly distributed on the support bushing.

[0012] According to an embodiment of the first aspect, the support bushing is made of smooth steel or bronze.

[0013] According to an embodiment of the first aspect, a coating is applied to the support bushing.

[0014] According to an embodiment of the first aspect, the coating is composed of polytetrafluoroethylene (PTFE).

[0015] A second aspect of the present disclosure provides a method for providing a clearance-free electric steering gear device for a commercial vehicle, the method comprising: providing a housing, the housing including a cylindrical portion extending in an axial direction, an inner wall of the cylindrical portion defining a groove and extending in the axial direction, the groove having at least two inwardly tapering walls; providing a ball screw disposed in the housing and extending in the axial direction, the ball screw defining a hole extending in a radial direction; providing a ball nut disposed in the housing and surrounding the ball screw, the ball nut being configured to rotate relative to the housing; providing an anti-rotation pin, the anti-rotation pin having a tapered end disposed in the hole, the tapered end having at least two tapered surfaces, Each tapered surface corresponds to a corresponding one of the at least two inwardly tapered walls; using a spring disposed in the hole to bias the anti-rotation pin in a radially outward direction toward the groove so that at least one tapered end of the anti-rotation pin engages the groove, thereby limiting the rotation of the ball screw relative to the housing; providing a support bushing, which is disposed in the housing between the ball screw and the housing, the support bushing being fixedly connected to the ball screw and defining a through hole, which is disposed between the groove and the hole of the ball screw, wherein the through hole is configured to receive the anti-rotation pin; and using the support bushing to absorb radial loads applied to the ball screw by the electric steering assembly and support the anti-rotation pin.

[0016] According to an embodiment of the second aspect, the method also includes: providing the inner wall of the cylindrical portion defining a second groove and extending in the axial direction, the second groove having at least two inwardly tapered walls; providing the ball screw disposed in the housing, the ball screw extending in the axial direction, and the ball screw defining a second hole extending in the radial direction; providing a second anti-rotation pin, the second anti-rotation pin having a tapered end disposed in the second hole, the tapered end having at least two tapered surfaces, each tapered surface corresponding to a corresponding one of the at least two inwardly tapered walls of the second groove; and providing a second spring, the second spring disposed in the second hole and being configured to bias the second anti-rotation pin toward the second groove in a radially outward direction, so that at least one tapered end of the second anti-rotation pin engages the second groove, thereby limiting the rotation of the ball screw relative to the housing.

[0017] According to an embodiment of the second aspect, the at least two tapered walls of the groove taper inwardly at a first angle, and wherein the at least two tapered surfaces of the tapered end of the anti-rotation pin taper at the first angle to match the taper of the groove.

[0018] According to an embodiment of the second aspect, the ball nut is configured to rotate on the ball screw and engage the threads of the ball screw.

[0019] According to an embodiment of the second aspect, the rotation of the ball nut on the ball screw causes the ball screw to translate axially in a left direction or a right direction based on the rotation direction of the ball nut.

[0020] According to an embodiment of the second aspect, engaging the groove with the anti-rotation pin limits rotation of the ball screw relative to the ball nut.

[0021] According to an embodiment of the second aspect, the support bushing is fixedly coupled to the ball screw using a plurality of bolts evenly distributed on the support bushing.

[0022] According to an embodiment of the second aspect, the support bushing is made of smooth steel or bronze.

[0023] According to an embodiment of the second aspect, a coating is applied to the support bushing, and wherein the coating consists of polytetrafluoroethylene (PTFE). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following will describe embodiments of the present disclosure in more detail based on the exemplary drawings. The present disclosure is not limited to the exemplary embodiments. In the embodiments of the present disclosure, all features described and / or shown herein may be used alone or in various combinations. The features and advantages of various embodiments of the present disclosure will become apparent by reading the following detailed description with reference to the accompanying drawings showing the following:

[0025] Figure 1 An overview of a gear assembly of a vehicle according to one or more examples of the present disclosure is shown;

[0026] Figure 2 A side cross-sectional view illustrating a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure;

[0027] Figure 3 A front cross-sectional view illustrating a housing of a gear assembly of a vehicle according to one or more examples of the present disclosure;

[0028] Figure 4 Another front cross-sectional view of a housing of a gear assembly of a vehicle is shown according to one or more examples of the present disclosure;

[0029] Figure 5 A perspective view showing a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure;

[0030] Figure 6 A perspective view showing a cross section of a housing of a gear assembly of a vehicle according to one or more examples of the present disclosure;

[0031] Figure 7 A view illustrating an anti-rotation pin according to one or more examples of the present disclosure;

[0032] Figure 8A Another view illustrating an anti-rotation pin according to one or more examples of the present disclosure;

[0033] Figure 8B Another view illustrating an anti-rotation pin according to one or more examples of the present disclosure;

[0034] Figure 8C A perspective view showing a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure;

[0035] Figure 9 Another overview of a gear assembly of a vehicle according to one or more examples of the present disclosure is shown;

[0036] Figure 10 Another side cross-sectional view showing a portion of a complete gear assembly of a vehicle according to one or more examples of the present disclosure;

[0037] Figure 11A Another cross-sectional view of a housing of a gear assembly of a vehicle is shown according to one or more examples of the present disclosure;

[0038] Figure 11B A partial cross-sectional view showing a housing of a gear assembly of a vehicle according to one or more examples of the present disclosure; and

[0039] Figure 12 A support bushing associated with a gear assembly of a vehicle is shown according to one or more examples of the present disclosure. DETAILED DESCRIPTION

[0040] Examples of the presented applications will now be described more fully below with reference to the accompanying drawings, in which some, but not all, examples of the applications are shown. In practice, the applications may be illustrated in different forms and should not be construed as limited to the examples set forth herein; rather, these examples are provided so that the applications will satisfy applicable legal requirements. Where possible, any term expressed herein in the singular is intended to also include the plural form, and vice versa, unless expressly indicated otherwise. Furthermore, as used herein, the terms "a" and / or "an" shall mean "one or more", even though the phrase "one or more" is also used herein. Furthermore, when something is said to be "based on" something else, it may also be based on one or more other things. In other words, unless expressly indicated otherwise, as used herein, "based on" means "based at least in part on" or "based at least in part on".

[0041] Commercial vehicles use electric power steering (EPS) gearing for steering. The EPS gearing consists of a ball screw, oriented transversely to the vehicle and housed in a gearing housing, and a ball nut surrounding the ball screw within the housing. Upon receiving a steering command from the driver, the vehicle's EPS gearing, including the ball nut and ball screw, is configured to transmit the driver's steering command to the vehicle's wheels. For example, upon receiving a steering command from the driver, the ball nut is configured to rotate around the ball screw. Due to the threads of the ball screw and ball nut, rotation of the ball nut causes the ball screw to translate left or right, depending on the direction of rotation of the ball nut. This translation of the ball screw causes the vehicle's wheels to rotate, thereby steering the vehicle. To facilitate translation of the ball screw, the ball screw has an anti-rotation feature that prevents it from rotating relative to the housing. However, due to manufacturing tolerances and normal wear, conventional anti-rotation features allow for a small amount of play, also known as clearance, between the ball screw and the housing.

[0042] One possible way to avoid clearance in an electric steering gear arrangement is to use anti-rotation pins with tapered ends with the ball screw. In some embodiments, two anti-rotation pins with tapered ends are placed in a common through hole extending radially through the ball screw so that their tapered ends face in a radially outward direction from the center of the ball screw. The inner cylindrical wall of the housing includes two axially extending grooves, which are configured to receive the tapered ends of the two anti-rotation pins. The groove includes tapered groove walls corresponding to the tapered ends of the anti-rotation pins. The tapering angle in the groove is the same as the tapering angle on the two anti-rotation pins. A spring is placed between the two anti-rotation pins in the ball screw to bias the two anti-rotation pins in a radially outward direction, keep the anti-rotation pins in contact with the groove, and ensure a tight fit between the pins and the groove. This arrangement of the anti-rotation pins prevents the ball screw from rotating relative to the housing and eliminates clearance, while allowing the ball screw to move axially relative to the housing. About Figures 1 to 5 This embodiment is discussed in more detail.

[0043] In another embodiment, any number of anti-rotation pins can be used to avoid play in the electric steering gear. The inner cylindrical wall of the housing can be modified to include the same number of grooves extending in the axial direction as the number of anti-rotation pins used. In this embodiment, instead of through holes, the ball screw has a hole for each anti-rotation pin and a corresponding spring to bias the anti-rotation pin in the radially outward direction toward the corresponding groove. Figures 6 to 12 Discussed in more detail in .

[0044] Figure 1 An overview of a gear assembly of a vehicle is shown, according to one or more examples of the present disclosure. Figure 1 The gear assembly 100 depicted in FIG. 1 is responsible for providing the steering function to the vehicle. Figure 1 The section 102 of the gear assembly 100 shown includes a ball screw and a ball nut, which are Figures 2 to 5 Discussed in more detail in .

[0045] Figure 2 A side cross-sectional view of a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure is shown. Portion 102 of the gear assembly 100 includes a housing 104 of the gear assembly that is cylindrical and extends transversely to the vehicle. The ball screw and ball nut (in Figure 3 and Figure 5 106) resides within housing 104. The ball nut and ball screw are configured to transmit steering commands received from the driver to the vehicle's wheels to steer the vehicle. To ground the ball screw to housing 104, housing 104 includes two tapered grooves to receive corresponding anti-rotation pins. The grooves of housing 104 taper at the same angle as the taper of anti-rotation pins 108 and 106 and extend the length of housing 104. Anti-rotation pins 106 and 108 are positioned within through-holes extending radially through the ball screw. A spring 110 is positioned between the two anti-rotation pins 106 and 108 to bias them radially outward, causing them to engage corresponding grooves in housing 104. By engaging the grooves, anti-rotation pins 106 and 108 prevent the ball screw from rotating relative to the housing when the ball nut rotates, but allow the ball screw to translate axially within the housing. When the ball nut rotates and the ball screw is held stationary using anti-rotation pins 106 and 108, the relative rotation between the ball nut and the ball screw causes the ball screw to translate in the axial direction relative to the housing. Because the tapered end of each anti-rotation pin is biased toward a groove with a corresponding tapered side, a constant tight fit is ensured, thereby eliminating play in the ball screw relative to the housing.

[0046] Figure 3 A front cross-sectional view of a housing of a gear assembly of a vehicle according to one or more examples of the present disclosure is shown. Figure 2 As disclosed, the housing 104 includes a ball screw 310 and a ball nut 312. The housing 104 of the gear assembly includes two tapered grooves on opposite ends. The tapered angle of the grooves in the housing 104 of the gear assembly matches the tapered angle on the anti-rotation pins 106 and 108. The two anti-rotation pins 106 and 108 are placed in the through holes of the ball screw 310 and inserted into the two tapered grooves of the housing 104. A spring 110 is placed between the two anti-rotation pins 106 and 108 to provide a radially outward force to keep the anti-rotation pins 106 and 108 in constant contact with the housing 104 of the gear assembly. The force applied to the anti-rotation pins 106 and 108, the ball screw 310 and the ball nut 312 is Figure 4 Discussed in more detail in .

[0047] Figure 4 Another front cross-sectional view of a housing of a gear assembly of a vehicle is shown, according to one or more examples of the present disclosure. Figure 4 Similar to Figure 3 ,but Figure 4 Discussed how Figure 3 The forces acting at the clearance between the anti-rotation pins 106 and 108, ball screw 310, ball nut 312, and housing 104 of the gear assembly are shown. Arrow 402 highlights the tapered angles of the anti-rotation pins 106 and 108 and the corresponding grooves in housing 104. The tapered angles of the anti-rotation pins 106 and 108 are similar to the tapered angles of the corresponding grooves in housing 104. A spring 110 positioned between the anti-rotation pins 106 and 108 provides a radial force, highlighted by arrow 404, that ensures that the anti-rotation pins 106 and 108 are constantly in contact with the grooves formed in housing 104. Because the ends of the grooves are slightly narrower than the ends of the anti-rotation pins, the spring ensures a constant, tight fit between the tapered surface of each pin and the tapered walls of each groove. Arrow 406 depicts the direction of rotation of the ball nut 312, which can be in either direction. As the ball nut 312 rotates relative to the ball screw, the threads of the ball nut and ball screw cause the ball screw to translate in an axial direction.

[0048] Figure 5A perspective view of a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure is shown. Perspective view 500 depicts the housing 104 of the gear assembly. The housing 104 of the gear assembly is cylindrical and extends in an axial direction. A ball screw 310 extends axially within the housing 104. A ball nut 312 is configured to rotate relative to the ball screw 310 and engage the threads of the ball screw 310. In some embodiments, the ball nut 312 may be housed in a portion of the housing 104 that allows rotation of the ball nut 312 while limiting translation. Anti-rotation pins 106 and 108 are positioned in through-holes extending radially through the ball screw 310. A spring 110 positioned between the anti-rotation pins 106 and 108 provides an outward radial force that ensures that the anti-rotation pins 106 and 108 maintain close contact with axially extending grooves 502 and 504 in the inner wall of the housing 104. Grooves 502 and 504 are formed on opposite sides of the ball screw 310 from the open end of the through-hole in the ball screw and have tapered sidewalls that taper at the same angle as the tapered surfaces of the anti-rotation pins 106 and 108. Grooves 502 and 504 extend axially along the length of the cylindrical portion of the housing 104. The anti-rotation pins 106 and 108, engaged with the grooves 502 and 504 of the housing 104, restrict any rotation of the ball screw 310 relative to the housing. Therefore, since the rotation of the ball screw 310 is restricted, circumferential rotation of the ball nut 312 causes the ball screw to translate in the axial direction.

[0049] In some embodiments, any number of anti-rotation pins can be used to avoid backlash in the electric steering gear. The inner cylindrical wall of the housing can be modified to include the same number of axially extending grooves as the number of anti-rotation pins used. In this embodiment, instead of through-holes, the ball screw has a hole for each anti-rotation pin and a corresponding spring to bias the anti-rotation pin radially outward toward the corresponding groove.

[0050] Figure 6 Another cross-sectional view of a housing of a gear assembly of a vehicle according to one or more examples of the present disclosure is shown. Figure 3 As disclosed, the housing 104 includes a ball screw 310 and a ball nut 312 . Figure 6 The cross-sectional view 600 is similar to Figure 3 300, but the cross-sectional view 600 has four tapered grooves 602, 604, 606 and 608 distributed in the housing 104 instead of Figure 3, two are shown in . In some embodiments, the number of tapered grooves in the housing 104 can be selected based on the number of anti-rotation pins used to prevent play in the electric steering gear arrangement. Instead of a through hole, the ball screw can include four separate holes, where each hole of the ball screw 310 corresponds to a corresponding tapered groove 602, 604, 606, or 608 in the housing 104. The anti-rotation pins 106, 108, 610, and 612 are placed in the holes of the ball screw 310, and a spring is placed in each hole at the first end of the anti-rotation pin to bias the tapered end of each anti-rotation pin in a radially outward direction to engage with the four tapered grooves 602, 604, 606, and 608 of the housing 104. For example, Figure 6 Springs 110, 614, 616, and 618 are shown at the ends of anti-rotation pins 106, 108, 610, and 612 inserted into ball screw 310. As previously described, springs 110, 614, 616, and 618 provide a radially outward force to keep anti-rotation pins 106, 108, 610, and 612 in constant contact with housing 104 of the gearing assembly.

[0051] The durability and performance of the anti-rotation pins 106, 108, 610, and 612 can be extended by modifying the anti-rotation pins by applying a coating or attaching a bearing material to the tapered ends of the anti-rotation pins. Figure 7 and Figures 8A to 8C The details of the coating applied to the anti-rotation pin and the bearing material attached to the anti-rotation pin are discussed in more detail in.

[0052] Figure 7Illustrations of anti-rotation pins according to one or more examples of the present disclosure are shown. Illustration 700 shows a view of anti-rotation pin 106 with a low-friction coating 702 applied to the tapered end of anti-rotation pin 106, which contacts the tapered groove of housing 104. In some embodiments, the low-friction coating enhances the life of anti-rotation pin 106 by reducing friction between the tapered end of anti-rotation pin 106 and the tapered groove of housing 104. For example, the coefficient of friction between the low-friction coating 702 applied to the tapered end of anti-rotation pin 106 and the tapered walls of the groove of housing 104 is less than the coefficient of friction between the tapered end of anti-rotation pin 106 and the tapered walls of the groove of housing 104. The low-friction coating 702 applied to the tapered end of anti-rotation pin 702 can have a thickness in the range of 0.0001 inches to 0.0005 inches. In some other examples, the coating can have a thickness of approximately 50 microns. In some cases, the low-friction coating 702 can include polytetrafluoroethylene (PTFE). Additionally and / or alternatively, the low-friction coating may be diaspore (a combination of acetal and TFE), polyetheretherketone (PEEK), ultra-high molecular weight polyethylene, a non-ferrous material such as aluminized bronze, or polyphenylene sulfide (PPS). The low-friction coating 702 may be applied to the anti-rotation pin 106 by spraying, electroplating, hot-dip galvanizing (galvanizing), vacuum deposition, and / or baking. In some embodiments, the low-friction coating of the same material may also be applied to the tapered groove of the housing 104 to reduce friction between the tapered end of the anti-rotation pin 106 and the tapered walls of the groove, thereby extending the life of the anti-rotation pin 106.

[0053] Figure 8A Another view of an anti-rotation pin according to one or more examples of the present disclosure is shown. Illustration 800 shows a view of the anti-rotation pin 106 in which the tapered end of the anti-rotation pin 106 is covered with a bearing material 802. In some embodiments, the bearing material enhances the life of the anti-rotation pin 106 by reducing the friction between the tapered end of the anti-rotation pin 106 and the tapered groove of the housing 104. For example, the coefficient of friction between the bearing surface 802 applied on the tapered end of the anti-rotation pin 106 and the tapered wall of the groove of the housing 104 is less than the coefficient of friction between the tapered end of the anti-rotation pin 106 and the tapered wall of the groove of the housing 104. In some embodiments, the coating 802 can be attached to the anti-rotation pin 106 using screws 804. As shown in FIG. Figure 8AAs shown, screw 804 can be attached to anti-rotation pin 106 on one side of anti-rotation pin 804, between the tapered ends and adjacent to the smaller side of the tapered ends. In some cases, a second screw (not shown) can be used on the opposite side to securely attach bearing material to the tapered ends of anti-rotation pin 106. In some embodiments, the bearing material can be attached to the tapered ends of anti-rotation pin 106 using an adhesive. In some embodiments, the bearing material can be retained in a recessed "pocket" machined into the face of the tapered end of the anti-rotation pin. In such embodiments, the depth of the pocket is designed to "capture" the bearing material. In some embodiments, two "L-shaped" pieces of bearing material 802 can be attached to cover each tapered surface of the tapered end of anti-rotation pin 106.

[0054] Additionally and / or alternatively, bearing material may also be applied to the tapered groove of housing 104 to reduce friction between the tapered end of anti-rotation pin 106 and the tapered walls of the groove and extend the life of anti-rotation pin 106. In some embodiments, the bearing material may be retained in a recessed "pocket" machined into the face of the tapered groove of housing 104. The depth of the pocket is designed to "capture" the bearing material.

[0055] Figure 8B Another view of an anti-rotation pin according to one or more examples of the present disclosure is shown. Figure 8B The view 850 of the anti-rotation pin 106 is shown to depict an alternative way of attaching the bearing material to the surface of the tapered end of the anti-rotation pin 106. Figure 8B As shown in view 850 of the embodiment of the present invention, a recess may be formed on the surface 852 of the tapered end to expose a second tapered surface 854. The bearing material 802 is configured to abut the second tapered surface 854 and fit within the recess of the tapered surface 852 of the anti-rotation pin 106. To securely retain the bearing material 802 within the anti-rotation pin 106, the bearing material 802 may have the same dimensions as the recess. The bearing material 802 may also have the same thickness as the recess. In some embodiments, the bearing material 802 is retained in place by being captured between the recess and a corresponding tapered groove in the housing 104.

[0056] Figure 8CA perspective view of a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure is shown. Perspective view 875 depicts the housing 104 of the gear assembly, which is cylindrical and extends in an axial direction. The ball screw 310 extends axially within the housing 104. Anti-rotation pins 106, 610, and 612 are positioned within bores in the ball screw 310. Springs 110, 616, and 618 (not shown) are positioned between the anti-rotation pins 106, 610, and 612 and the bores, providing an outward radial force that ensures constant, close contact between the anti-rotation pins 106, 610, and 612 and corresponding axially extending grooves in the inner wall of the housing 104. As shown in perspective view 875, bearing material 802 is attached to the tapered surfaces of the anti-rotation pins 106, 610, and 612.

[0057] The bearing material can be a steel backing sheet with bronze and polymer fillers. In some embodiments, the bearing material can be provided as a steel sheet with a bronze layer. The bronze layer may have holes therein, which are filled with a filler material such as graphite or PTFE. These layers are then rolled into a bushing and used as the material to create the bearing surface. Additionally and / or alternatively, the bearing material 802 can include polytetrafluoroethylene (PTFE) or other suitable materials.

[0058] In some embodiments, a support bushing can be used to support and stabilize the ball screw. The support bushing is an improvement that can absorb external radial loads applied to the ball screw and, in doing so, reduce radial movement of the ball screw and anti-rotation pin, which reduces stress on the anti-rotation pin.

[0059] Figure 9 Another overview of a gear assembly of a vehicle is shown, according to one or more examples of the present disclosure. Figure 9 The gear assembly 900 is similar to Figure 1 The gear assembly 100 shown. Figure 1 As discussed, Figure 1The gear assembly 900 depicted in FIG is responsible for providing steering functionality to the vehicle. When a steering command is received at the gear assembly 900, the steering command is transmitted to the wheels connected to the gear assembly 900 via the tie rods 902 of the gear assembly 900. In some embodiments, the steering of the vehicle's wheels imposes an external load on the ball screw 310 via the tie rods 902. For example, the movement of the wheels in response to the steering command causes an arcuate motion in the tie rod 902. The arcuate motion of the tie rod 902 may change the connection angle between the tie rod 902 and the ball joint connecting the tie rod to the ball screw 310. The change in the connection angle of the ball joint may impose a load on the ball screw 310. Additionally, the vehicle's suspension, which is also attached to the vehicle's wheels, may impose an external load on the ball screw 310. External loads originating from the tie rods 902 or suspension of the vehicle may appear as radial loads on the ball screw 310. This is in Figures 10 to 12 Discussed in more detail in .

[0060] Figure 10 Another side cross-sectional view of a portion of a complete gear assembly for a vehicle according to one or more examples of the present disclosure is shown. Portion 1000 of the gear assembly 900 includes a housing 104 of the gear assembly that is cylindrical and extends transversely to the vehicle. The ball screw and ball nut (in Figure 3 and Figure 5106) resides within housing 104. The ball nut and ball screw are configured to transmit steering commands received from the driver to the vehicle's wheels to steer the vehicle. To ground the ball screw to housing 104, housing 104 includes tapered grooves to receive corresponding anti-rotation pins 108 and 106. The grooves of housing 104 taper at the same angle as the taper of anti-rotation pins 108 and 106 and extend the length of housing 104. Anti-rotation pins 106 and 108 are positioned within separate bores extending in a radial direction. Springs 614 and 110 are positioned between anti-rotation pins 106 and 108 and the surfaces of the corresponding bores to bias the anti-rotation pins 106 and 108 radially outward, causing them to engage with corresponding grooves in housing 104. By engaging the grooves, anti-rotation pins 106 and 108 prevent rotation of the ball screw relative to the housing when the ball nut rotates, but allow the ball screw to translate axially within the housing. As the ball nut rotates and the ball screw is held stationary using anti-rotation pins 106 and 108, the relative rotation between the ball nut and the ball screw causes the ball screw to translate in an axial direction relative to the housing. Because the tapered end of each anti-rotation pin is biased toward a groove having a corresponding tapered side, a constant tight fit is ensured, thereby eliminating play in the ball screw relative to the housing. In some embodiments, a radial load is applied to the ball screw 310 based on the arcuate motion of the tie rod 902, which causes a change in the connection angle between the tie rod 902 and the ball joint connecting the tie rod to the ball screw 310. Additionally, the radial load can be applied to the ball screw 310 by a suspension of a vehicle connected to the gear assembly (not shown).

[0061] Without the support bushings, external loads applied to the ball screw may be applied to the anti-rotation pins 106 and 108. The external loads applied to the ball screw may cause radial motion of the ball screw, which in turn causes radial displacement of the anti-rotation pins 106 and 108, which may increase wear on the anti-rotation pins 106 and 108, thereby reducing the effectiveness of the anti-rotation pins 106 and 108 in preventing backlash during steering.

[0062] The support bushing 1004 mounted around the anti-rotation pin can absorb radial loads applied to the ball screw 310. By absorbing the radial loads, the support bushing 1004 reduces radial movement of the ball screw 310 and stabilizes the ball screw. By stabilizing the ball screw, the support bushing 1004 can reduce radial movement of the anti-rotation pins 106 and 108. Once the radial movement of the anti-rotation pins 106 and 108 is reduced, the anti-rotation pins 106 and 108 can only respond to the torque applied to the ball screw 310 in response to the steering command received from the electric steering gear device, thereby effectively working to hold the ball screw 310 relative to the ball nut 312.

[0063] Figure 11A Another cross-sectional view of a housing of a gear assembly of a vehicle is shown, according to one or more examples of the present disclosure. Figure 11A The view 1100 shows the support bushing 1004 in the gear assembly 900 ( Figure 9 ) in the housing 104. View 1100 depicts the housing 104 housing the ball nut 312 ( Figure 11A Not shown), ball screw 312 ( Figure 11A ), anti-rotation pins 106, 108, 610, and 612 placed in the tapered grooves of the housing 104, and corresponding anti-rotation pins 108, 106, 610, and 612 ( Figure 11A 610 and 612) of each of the springs 110, 614, 616 and 618 (not shown in FIG. Figure 11A 616 and 618 are not shown in FIG). The support bushing 1004 is placed between the housing 104 and the ball screw 310. In some embodiments, the support bushing 1004 may include a hole corresponding to the tapered groove of the housing 104 and the hole in the ball screw 310. Figure 11A As shown in view 1100 of , the bore of support bushing 1004 receives anti-rotation pins 106 , 108 , 610 , and 612 .

[0064] Figure 11B A partial cross-sectional view of a housing of a gear assembly of a vehicle is shown, according to one or more examples of the present disclosure. Figure 11B View 1150 of FIG. 1 provides a three-dimensional (3D) view of the support bushing 1004 without the housing 104 . As seen in view 1150 , the support bushing 1004 is attached to the ball screw 310 using a plurality of bolts 1102 . Figure 11B View 1150 also shows the tapered ends of anti-rotation pins 106 and 610 inserted through the holes of support bushing 1004 into ball screw 310. The tapered ends of anti-rotation pins 106 and 610 are biased against the tapered walls of corresponding grooves of housing 104 (not shown in view 1150).

[0065] Figure 12 A support bushing associated with a gear assembly of a vehicle is shown according to one or more examples of the present disclosure. Figure 12The support bushing 1004 shown is circular and is designed to surround the ball screw 310. The support bushing 1004 may include holes 1202 and 1204 of different shapes. The holes 1202 of the support bushing 1004 are configured to receive anti-rotation pins. In some embodiments, the number of holes 1202 provided in the support bushing 1004 may depend on the number of anti-rotation pins installed on the ball screw 310. In some embodiments, the holes 1202 have sliding contacts to accommodate the tapered ends ( Figure 12 310). The holes 1204 of the support bushing 1004 are configured to receive the bolts 1102 that attach the support bushing 1004 to the ball screw 310. Regarding the number of holes 1202, the number of holes 1204 that can be provided in the support bushing 1004 can depend on the number of bolts 1102 used to secure the support bushing 1004 to the ball screw 310. Additionally and / or alternatively, the support bushing 1004 can be attached to the ball screw 310 using a pin, a retaining ring, a machined shoulder, or other mechanism.

[0066] The support bushing 1004 may be constructed of smooth steel, bearing metal (eg, bronze), or bearing material, as described with respect to FIG. Figure 8A In some embodiments, a coating may be applied to the support bushing 1004. Figure 7 The coating may be applied as discussed in detail herein. The application of the coating may enhance the durability of the support bushing by reducing the coefficient of friction between the support bushing 1004 and the ball screw 310.

[0067] Although the subject matter of the present disclosure has been shown and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary rather than restrictive. Any statements made herein characterizing the invention are also to be considered illustrative or exemplary rather than restrictive, as the invention is defined by the claims. It should be understood that changes and modifications may be made by one of ordinary skill in the art within the scope of the appended claims, which may include any combination of features from the different embodiments described above.

[0068] The terms used in the claims should be interpreted as having the broadest reasonable interpretation consistent with the preceding description. For example, the use of the article "a" or "the" when introducing an element should not be interpreted as excluding a plurality of elements. Similarly, the statement of "or" should be interpreted as inclusive, so that the statement of "A or B" does not exclude "A and B" unless it is clear from the context or the preceding description that only one of A and B is intended. In addition, the statement of "at least one of A, B, and C" should be interpreted as one or more of a group of elements consisting of A, B, and C, and should not be interpreted as requiring at least one of each of the listed elements A, B, and C, regardless of whether A, B, and C are related as categories or in other ways. In addition, the statement of "A, B, and / or C" or "at least one of A, B, or C" should be interpreted as including any singular entity from the listed elements (e.g., A), any subset from the listed elements (e.g., A and B), or the entire list of elements A, B, and C.

Claims

1. An electric power steering assembly for a commercial vehicle, comprising: a housing including a cylindrical portion extending in an axial direction, an inner wall of the cylindrical portion defining a groove extending in the axial direction, the groove having at least two inwardly tapering walls; a ball screw disposed in the housing, extending in the axial direction and defining a hole extending in the radial direction; a ball nut disposed in the housing, surrounding the ball screw, and configured to rotate relative to the housing; an anti-rotation pin having a tapered end disposed in the bore, the tapered end having at least two tapered surfaces, each tapered surface corresponding to a respective one of the at least two inwardly tapered walls; a spring disposed in the bore and configured to bias the anti-rotation pin in a radially outward direction toward the groove such that at least one tapered end of the anti-rotation pin engages the groove and thereby limits rotation of the ball screw relative to the housing, and a support bushing disposed in the housing between the ball screw and the housing, the support bushing being fixedly coupled to the ball screw and defining a through hole disposed between the groove and the bore of the ball screw, The through hole is configured to receive the anti-rotation pin, The support bushing absorbs a radial load applied to the ball screw by the electric power steering assembly and supports the anti-rotation pin.

2. The electric power steering assembly according to claim 1, further comprising: The inner wall of the cylindrical portion defines a second groove and extends in the axial direction, the second groove having at least two inwardly tapering walls; The ball screw is disposed in the housing, extends in the axial direction, and defines a second hole extending in the radial direction; a second anti-rotation pin having a tapered end disposed in the second hole, the tapered end having at least two tapered surfaces, each tapered surface corresponding to a respective one of the at least two inwardly tapered walls of the second groove; as well as A second spring is disposed in the second hole and is configured to bias the second anti-rotation pin in a radially outward direction toward the second groove so that at least one tapered end of the second anti-rotation pin engages the second groove and thereby limits rotation of the ball screw relative to the housing.

3. The electric power steering gear device according to claim 1, wherein: The at least two tapered walls of the groove taper inwardly at a first angle.

4. The electric power steering gear device according to claim 3, wherein: The at least two tapered surfaces of the tapered end of the anti-rotation pin taper at the first angle to match the taper of the groove.

5. The electric power steering gear device according to claim 1, wherein: The ball nut is configured to rotate on the ball screw and engage threads of the ball screw.

6. The electric power steering gear device according to claim 5, wherein: The rotation of the ball nut on the ball screw causes the ball screw to translate axially in a left or right direction based on the direction of rotation of the ball nut.

7. The electric power steering gear device according to claim 1, wherein: Engaging the groove with the anti-rotation pin limits rotation of the ball screw relative to the ball nut.

8. The electric power steering gear device according to claim 1, wherein: The support bushing is fixedly coupled to the ball screw using a plurality of bolts evenly distributed on the support bushing.

9. The electric power steering gear device according to claim 1, wherein: The support bushings are constructed from smooth steel or bronze. 10 . The electric steering gear apparatus of claim 1 , further comprising applying a coating on the support bushing.

11. The electric power steering gear device according to claim 1, wherein: The coating consists of polytetrafluoroethylene (PTFE).

12. A method of providing a backlash-free electric steering gear arrangement for a commercial vehicle, the method comprising: providing a housing including a cylindrical portion extending in an axial direction, an inner wall of the cylindrical portion defining a groove extending in the axial direction, the groove having at least two inwardly tapering walls; providing a ball screw disposed in the housing, extending in the axial direction and defining a bore extending in the radial direction; providing a ball nut disposed in the housing, surrounding the ball screw, and configured to rotate relative to the housing; providing an anti-rotation pin having a tapered end disposed in the bore, the tapered end having at least two tapered surfaces, each tapered surface corresponding to a respective one of the at least two inwardly tapered walls; biasing the anti-rotation pin in a radially outward direction toward the groove using a spring disposed in the bore such that at least one tapered end of the anti-rotation pin engages the groove and thereby restricts rotation of the ball screw relative to the housing; providing a support bushing disposed in the housing between the ball screw and the housing, the support bushing being fixedly coupled to the ball screw and defining a throughbore disposed between the groove and the bore of the ball screw, wherein the throughbore is configured to receive the anti-rotation pin; as well as The support bushing is used to absorb radial loads applied to the ball screw by the electric power steering assembly and to support the anti-rotation pin.

13. The method according to claim 12, further comprising: providing the inner wall of the cylindrical portion defining a second groove and extending in the axial direction, the second groove having at least two inwardly tapering walls; providing the ball screw disposed in the housing, extending in the axial direction and defining a second hole extending in the radial direction; providing a second anti-rotation pin having a tapered end disposed in the second aperture, the tapered end having at least two tapered surfaces, each tapered surface corresponding to a respective one of the at least two inwardly tapered walls of the second recess; as well as A second spring is provided, which is disposed in the second hole and is configured to bias the second anti-rotation pin in a radially outward direction toward the second groove so that at least one tapered end of the second anti-rotation pin engages the second groove and thereby limits rotation of the ball screw relative to the housing.

14. The method according to claim 12, wherein: The at least two tapered walls of the groove taper inwardly at a first angle, and The at least two tapered surfaces of the tapered end of the anti-rotation pin are tapered at the first angle to match the tapering of the groove.

15. The method according to claim 12, wherein: The ball nut is configured to rotate on the ball screw and engage threads of the ball screw.

16. The method according to claim 15, wherein The rotation of the ball nut on the ball screw causes the ball screw to translate axially in a left direction or a right direction based on the direction of rotation of the ball nut.

17. The method according to claim 1, wherein Engaging the groove with the anti-rotation pin limits rotation of the ball screw relative to the ball nut.

18. The method according to claim 1, wherein The support bushing is fixedly coupled to the ball screw using a plurality of bolts evenly distributed on the support bushing.

19. The method according to claim 1, wherein The support bushings are constructed from smooth steel or bronze.

20. The method of claim 1 further comprising applying a coating to the support bushing, and wherein The coating consists of polytetrafluoroethylene (PTFE).

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