Device for supporting and fixing steering screw for steer-by-wire system

Abstract

The utility model discloses a device for supporting and fixing a steering screw rod of a steer-by-wire system. The servo end supporting mechanism is composed of a ball screw nut and a ball bearing, the ball screw nut drives a ball screw to move axially through the rotating motion of the ball screw nut, and the ball screw nut is supported on the steering machine shell through the bearing; the non-servo end supporting mechanism is connected with the steering machine shell to support the steering lead screw, meanwhile, it is guaranteed that the steering lead screw only moves in the axial direction, and circumferential rotation of the steering lead screw is limited. The utility model has the advantages of low cost, high reliability and excellent friction performance.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of automobile, concretely relates to a device for supporting and fixing steering screw rod for steer-by-wire system. BACKGROUND

[0002] Parallel axis type electric power assisted steering system is one of the typical forms of electric power assisted steering system favored by the market at present, which usually adopts two-stage mechanical reduction mechanism combined with belt transmission and ball screw transmission to convert the torque and rotary motion of electric motor into rack force and linear motion of steering rack (steering screw rod), as shown in the figure: steering wheel 3 is mechanically connected to input shaft 7-1 of steering engine through steering column 26 and intermediate connecting shaft 4, output shaft 7-2 drives rack to move linearly along its axis direction in the form of gear cooperation with rack area 5-2 of steering rack 5; torque and angle sensing unit 6 is integrated on input shaft 7-1 for detecting torque and angle signal of driver rotating steering wheel, and the signal is transmitted to electronic control unit 9 of driving motor 8 through wire harness 10; electronic control unit 9 processes and calculates according to the input signal in a defined logic method, and outputs current control driving motor 8 to rotate in a certain size and direction; a group of belt transmission mechanism 11 transmits output torque of driving motor 8 to circulating ball nut 12 of ball screw, and the circulating ball nut is fixed in steering engine housing 18 through ball bearing 13; circulating ball nut 12 rotates to drive steering screw rod 5 to move along the axial direction of circulating ball nut 12, and steering drag link 14 connected with the both ends of steering screw rod in the form of spherical joint thus realizes spatial motion, drives tire to rotate around a certain axis, and finally completes steering function. Figure 3

[0003] The expected behavior of steering rack 5 is linear motion along its axis without rotation in the circumferential direction, so the steering system needs to be provided with a device for supporting and fixing steering rack. In the above electric power assisted steering system, the supporting and fixing of steering rack 5 in steering engine housing 18 is realized as follows: one end is supported and fixed through ball screw nut 12 and ball bearing 13 outside the ball screw nut, and ball bearing 13 is fixedly connected with steering engine housing 18; the other end is supported and fixed through the cooperation of output shaft 7-2 gear with rack area 5-2 of steering rack 5, and pressing block device arranged on the back surface of the rack area 5-2. The pressing block device is composed of pressing block assembly 16 and lining plate 17, as shown in the figure. Thus, the combination of output shaft 7-2 and pressing block device can completely restrict the rotational motion freedom degree of rack along its axis. Figure 4

[0004] ​​However, on the one hand, the large-area sliding friction contact between the lining 17 of the pressing block device and the rack 5 increases the resistance of the axial movement of the steering rack, which reduces the mechanical transmission efficiency of the system; on the other hand, the meshing gap between the output shaft 7-2 gear and the steering rack 5 is generally ensured by adjusting the axial position of the pressing block device in its mounting hole, and the gap adjustment and improper fit here are an important source of unexpected noise generated by the steering machine. Moreover, the pressing block device may to some extent over-constrain the movement of the steering rack 5, limiting the flexible operation of the rack.

[0005] With the development of the automobile industry and the iteration and upgrading of technology, users pay more and more attention to the performance of driving a car, such as control, comfort, safety and intelligence. In the current wave of development of new energy vehicles, software-defined vehicles and multi-system intelligent collaboration have become a trend, and the key to multi-system intelligent collaboration lies in the drive-by-wire technology. The chassis is the core executive mechanism of vehicle motion control, so the drive-by-wire chassis is the basis for realizing software-defined vehicles. As an important part of the drive-by-wire chassis, drive-by-wire steering emerges as the times require. Figure 1 The main difference between the drive-by-wire steering system shown in FIG. 1 and the traditional electric power steering system in structure is that the drive-by-wire steering system cancels the mechanical connection part between the steering column 26 and the steering rack 5 of the steering machine, including the intermediate connecting shaft 4, the input shaft 7-1 and the output shaft 7-2 and other parts; and the torque and angle sensing unit 15 is installed below the steering wheel, and is directly connected to the electronic control unit 9 of the steering actuator through a wire harness.

[0006] For the aforementioned drive-by-wire steering system, there is no mechanical coupling between the steering wheel 3 and the steering actuator, and the steering intention of the driver is transmitted through electrical signals, and the steering power comes entirely from the driving motor 8, so the input shaft 7-1, the output shaft 7-2, the toothed area 5-2 of the steering rack 5 and the pressing block device in the traditional electric power steering system 1 are no longer applicable, and other structural schemes must be considered to support and fix the non-servo end 5-3 of the steering screw 5. The design purpose of this structure is to provide support for the axial movement of the steering screw 5, and to overcome the torque load on the steering screw 5 due to the rotational drive of the circulating ball nut 12, i.e. to circumferentially fix the steering screw 5 and limit its rotational movement degree of freedom. At the same time, this structure needs to have appropriate stiffness and damping characteristics to reduce the influence of external impact forces. In addition, friction and noise should be reduced as much as possible. SUMMARY

[0007] The purpose of the utility model is to provide a device for supporting and fixing a steering screw for a drive-by-wire steering system, which has low cost, high reliability and excellent friction performance.

[0008] To solve the above technical problems, the utility model provides a device for supporting and fixing steering screw rod for steer -by -wire system, include: steering casing, servo end support mechanism: constitute by ball screw nut and ball bearing, the ball screw nut passes through its rotary motion drive ball screw shaft to move, ball screw nut is supported on steering casing through bearing, non servo end support mechanism: give the steering screw rod with the connection of steering casing to support, guarantee the steering screw rod only makes axial movement simultaneously, limit the circumferential rotation of steering screw rod.

[0009] Preferably, the non-servo end support mechanism comprises a retaining element, a rolling element and a sleeve element, the rolling element is freely rotatably embedded in the retaining element, the distal axial end of the rolling element is freely rotatably supported on the sleeve element, the proximal axial end is freely rotatably supported on the circumferal surface of the steering screw rod, and the outer sleeve surface of the sleeve element is supported and connected with the steering casing.

[0010] Preferably, the retaining element comprises a plurality of holes for accommodating the rolling element, which are uniformly distributed in the circumferal direction and arranged in at least one column in the axial direction, an inner circumferal surface boss, a flange edge and a protrusion which are in contact with the end surface step of the sleeve element, openings located on both sides of the protrusion, and an outer circumferal surface boss.

[0011] Preferably, the rolling element is uniformly distributed in multiple groups in the circumferal direction, and cooperates with the arc-shaped cross-section groove of the steering screw rod; at the same time, the rolling element is limited in the groove of the sleeve element and the groove of the steering screw rod.

[0012] Preferably, the sleeve element has a circular arc triangular outer circumferal surface which is matched with the mounting hole of the casing to circumferally fix the steering screw rod and limit the rotation of the steering screw rod.

[0013] Preferably, the sleeve element comprises an end surface step, an inner circumferal surface axial groove and an outer circumferal surface plane, wherein the end surface step is in contact with the flange edge and the protrusion of the retaining element respectively to realize the axial positioning of the retaining element in the sleeve, the inner circumferal surface axial groove is used for accommodating the rolling element, and the outer circumferal surface plane is in contact with the casing to limit the rotary motion of the sleeve element relative to the casing.

[0014] Preferably, the sleeve element further comprises a circumferal groove on the outer circumferal surface, and an O-ring is installed in the circumferal groove to compensate for the assembly gap between the outer circumferal surface of the sleeve element and the casing.

[0015] Preferably, the material of the retaining element is nylon.

[0016] Preferably, the support area of the non-servo end of the steering screw is designed with multiple sets of circumferentially uniformly distributed axial grooves with circular arc cross-sections for accommodating the rolling elements, the shape of the groove cross-section is adapted to the rolling elements, and the length of the groove can cover the stroke range of the steering screw, and the depth of the groove is designed to cover one third of the cross-sectional width of the rolling elements.

[0017] Preferably, the sleeve element and the rolling element are made of bearing steel.

[0018] The technical effects of the utility model are:

[0019] The support mechanism 19 can realize the axial movement of the steering screw and the circumferential positioning and rotation limiting of the steering screw in the steer-by-wire system without the input shaft and the traditional lining type pressure block.

[0020] The support mechanism 19 can make the rolling element 23 and the steering screw groove 20 cooperate in the form of rolling friction, thereby realizing low-noise, stable and flexible screw movement, improving the noise performance and durability of the steering machine, reducing the system friction, and improving the system efficiency.

[0021] The specifications of the rolling element 23 and the O-ring stiffness 25 of the support mechanism 19 can be adjusted according to requirements to meet different product requirements.

[0022] The support mechanism 19 can realize flexible arrangement of the position in the steering machine, can ensure that the steering machine is compatible with the structure arrangement of different vehicle requirements, and improves the universality of the product. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a schematic diagram for the utility model used in the steer-by-wire system.

[0024] Figure 2 It is a space layout of the screw support structure for the utility model used in the steer-by-wire system.

[0025] Figure 3 It is a parallel shaft type electric power steering system in the prior art.

[0026] Figure 4 It is the support of the output shaft and the pressure block assembly on the toothed screw in the prior art.

[0027] Figure 5 It is an exploded view of the device for supporting and fixing the screw for the utility model used in the steer-by-wire system.

[0028] Figure 6 It is a schematic diagram of the sleeve element in the device for supporting and fixing the steering screw for the utility model used in the steer-by-wire system.

[0029] Figure 7 This is a schematic diagram of the retaining element in the device for supporting and fixing the steering screw in the steer-by-wire system of this utility model.

[0030] Figure 8 This is an axial cross-sectional view of the lead screw support and fixing structure of this utility model.

[0031] Figure 9 for Figure 8 AA section diagram. Detailed Implementation

[0032] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can fully understand other advantages and technical effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through different specific embodiments, and the details in this specification can also be applied based on different viewpoints, with various modifications or changes made without departing from the overall design concept of the invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. The following exemplary embodiments of this utility model can be implemented in many different forms and should not be construed as being limited to the specific embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of this utility model thorough and complete, and to fully convey the technical solutions of these exemplary embodiments to those skilled in the art.

[0033] Example 1

[0034] like Figure 1 As shown, the device for supporting and fixing the steering screw in the steer-by-wire system is used in the steer-by-wire system. The principle of the steer-by-wire system is as follows: the torque and angle sensing unit 15 installed under the steering wheel 3 measures the torque and angle of the driver's rotation of the steering wheel, and then transmits the signal directly to the electronic control unit 9 in the steering system through the wiring harness 10; the electronic control unit 9 processes and calculates the input signal according to the defined logic method, and outputs a current of a certain magnitude and direction to control the rotation of the drive motor 8; a set of belt drive mechanism 11 transmits the output torque of the drive motor 8 to the recirculating ball nut 12 of the ball screw, which is fixed in the steering gear housing 18 by ball bearing 13; the rotation of the recirculating ball nut 12 drives the steering screw 5 to move axially along the recirculating ball nut 12, and the steering tie rod 14 connected to the two ends of the steering screw with ball joints realizes spatial movement, drives the tire to rotate around a certain axis, and finally completes the steering function.

[0035] Device 19 for supporting and fixing the steering screw 5 in the steer-by-wire system, such as Figure 2As shown, the device 19 is arranged at the non-servo end support area 5-3 of the steering screw 5, coaxially arranged along the axial outer side of the steering screw 5, and fixed through the shell 18 and the damping element 21. The device 19 is composed of the retaining element 22, the rolling element 23, the sleeve element 24, and the O-ring 25. Through the cooperation of the plurality of rolling elements 23 uniformly distributed in the circumferential direction and the circular arc cross-section groove 20 of the screw, the function of supporting the axial movement of the steering screw is realized; at the same time, the rolling element 23 is limited in the groove 24-3 of the sleeve element 24 and the groove 20 of the steering screw, and the outer circumferential surface 24-4 of the sleeve element 24 is adapted to the mounting hole of the shell 18, so that the function of circumferentially fixing the steering screw 5 and limiting the rotation of the steering screw 5 is realized.

[0036] As shown in the drawings, Figure 5 As shown, the device 19 for supporting and fixing the steering screw of the steer-by-wire system is designed at the non-servo end 5-3 support area of the steering screw 5: coaxially arranged along the axial outer side of the steering screw 5, and fixed through the shell 18 mounting hole stepped surface and the damping element 21. The device 19 is composed of the retaining element 22, the rolling element 23, the sleeve element 24, and the O-ring 25. Through the cooperation of the plurality of rolling elements 23 uniformly distributed in the circumferential direction and the circular arc cross-section groove 20 of the steering screw 5, the function of supporting the axial movement of the steering screw 5 is realized; at the same time, the rolling element 23 is limited in the groove 24-3 of the sleeve element 24 and the groove 20 of the steering screw, and the outer circumferential surface 24-4 of the sleeve element 24 is adapted to the mounting hole of the shell 18, so that the function of circumferentially fixing the steering screw 5 and limiting the rotation of the steering screw 5 is realized.

[0037] As shown in the drawings, Figure 6 As shown, the sleeve element 24 includes the outer circumferential groove 24-1, the end face step 24-2, the inner circumferential axial groove 24-3, and the outer circumferential plane 24-4. Among them, the outer circumferential groove 24-1 is used to accommodate the O-ring 25; the end face step 24-2 is in contact with the flange edge 22-3 and the protrusion 22-4 of the retaining element 22 respectively to realize the axial positioning of the retaining element in the sleeve; the inner circumferential axial groove 24-3 is used to accommodate the rolling element 23; and the outer circumferential plane 24-4 is in contact with the shell 18 to limit the rotational movement of the sleeve element 24 relative to the shell.

[0038] As shown in the drawings, Figure 7 As shown, the retaining element 22 includes the holes 22-1 for accommodating the rolling elements 23, which are uniformly distributed in the circumferential direction and arranged in at least one column in the axial direction, the inner circumferential boss 22-2, the flange edge 22-3 and the protrusion 22-4 in contact with the end face step 24-2 of the sleeve element 24, the openings 22-5 located on both sides of the protrusion, and the outer circumferential boss 22-6.

[0039] AsFigure 2 As shown, the steering screw 5 is designed with a plurality of circumferentially uniformly distributed axial grooves 20 in the support area of the non-servo end 5-3, which are circular arc in cross section and used to accommodate the rolling elements 23. The cross section of the groove 20 is adapted to the rolling elements 23, and the length thereof can cover the stroke range of the steering screw 5. The depth of the groove 20 is designed to cover one third of the cross section width of the rolling elements 23, so that the strength of the steering screw will not be excessively weakened, and on the basis of realizing the functions of supporting and circumferentially fixing the steering screw, sufficient strength of the screw is ensured, and meanwhile the manufacturing difficulty of the groove is relatively low.

[0040] As shown in Figure 8 and Figure 9 The rolling elements 23 are held in the circumferentially uniformly distributed holes 22-1 of the holding elements 22 arranged in at least one column in the axial direction, and one end of the rolling elements 23 is accommodated in the circular arc groove 24-3 of the sleeve element 24, and the other end is accommodated in the circular arc groove 20 of the steering screw 5 arranged opposite the circular arc groove 24-3 of the sleeve element 24 in the support area of the non-servo end 5-3. Therefore, the rolling elements are limited in the raceway composed of the groove 24-3 and the groove 20 by the sleeve element, the holding element and the steering screw, and rotate around the spherical center of the rolling elements. At the same time, the groove 24-3 and the groove 20 also provide support for the movement of the rolling elements 24.

[0041] The O-ring 25 is installed in the circumferential groove 24-1 of the outer circumferential surface of the sleeve element 24, which is used to compensate the assembly gap between the outer circumferential surface of the sleeve element 24 and the housing 18, so that the sleeve element 24 will not produce friction noise when it is moved or impacted under force. At the same time, it has a certain motion damping effect, which makes the steering screw 5 quickly recover smoothly and slow down the impact when it is impacted.

[0042] In order to realize the above structure, the materials of the sleeve element 24 and the rolling elements 23 are preferably bearing steel, and the preferred material of the holding element 22 is nylon.

[0043] The support forms of the two ends of the steering screw 5 are designed as one end is the support structure composed of the ball screw nut 12 and the ball bearing 13, and the other end is the support structure 19 composed of the holding element 22, the rolling element 23, the sleeve element 24 and the O-ring 25, and the two groups of support structures are fixedly matched with the steering housing. At the same time, the ball screw nut 12 can drive the screw 5 to move in the axial direction, and theoretically the contact area between the rolling elements 23 and the screw is small, which will not excessively constrain the screw.

[0044] The rolling element 23 has a rolling rotation movement characteristic, which realizes the purpose of rolling friction movement when cooperating with the screw groove 20, so as to greatly reduce the resistance of the screw movement, and compared with the traditional lining type support structure, the movement noise and the wear amount after long time operation are greatly reduced, so the noise performance and the durability of the steering machine are optimized.

[0045] Meanwhile, the support structure 19 can be flexibly arranged at a certain axial position on the steering machine according to the needs, which can ensure that the steering machine is compatible with the structure arrangement of different vehicle models, and improves the universality of the product.

[0046] Since the plurality of rolling elements 23 are distributed at the same axial position on the circumference of the steering screw, and the rolling element 23 is limited in the groove 24-3 of the sleeve element 24 and the steering screw groove 20, and the circular arc triangular outer circumferential surface 24-4 of the sleeve element 24 is matched with the mounting hole of the shell 18, the rotating movement trend of the screw 5 can be completely limited, so as to ensure that the steering screw 5 can only move linearly along the axis when the ball screw nut 12 drives the steering screw 5 to move, and the steering screw 5 does not rotate, thereby ensuring that the steering machine can accurately perform the required screw movement.

[0047] The utility model is described in detail through the specific embodiment and the example, but these do not constitute the limitation to the utility model. In the case where the principle of the utility model is not departed from, the person skilled in the art can also make many deformation and improvement, and these also should be regarded as the protection range of the utility model.

Claims

1. A device for supporting and securing a steering screw for a steer-by-wire system, characterized in that, The application relates to a steering gear housing and a servo end support mechanism. The servo end support mechanism comprises a ball screw nut and a ball bearing, the ball screw nut drives the ball screw shaft to move axially through the rotation of the ball screw nut, and the ball screw nut is supported on the steering gear housing through the bearing. The non-servo end support mechanism comprises a retaining element, a rolling element and a sleeve element, the rolling element is freely rotatably embedded in the retaining element, the distal axial end of the rolling element is freely rotatably supported on the sleeve element, the proximal axial end of the rolling element is freely rotatably supported on the circumferential surface of the steering screw, and the outer sleeve surface of the sleeve element is supported and connected with the steering gear housing. The retaining element comprises a plurality of holes for accommodating the rolling elements which are uniformly distributed in the circumferential direction and arranged in at least one column in the axial direction, an inner circumferential surface boss, a flange edge and a protrusion which are in contact with the end surface step of the sleeve element, openings located on both sides of the protrusion and an outer circumferential surface boss.

2. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 1, characterized in that The rolling elements are uniformly distributed in multiple groups in the circumferential direction and are in contact with the arc-shaped groove of the steering screw; meanwhile, the rolling elements are limited in the groove of the sleeve element and the groove of the steering screw.

3. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 2, characterized in that The sleeve element has an arc-triangle-shaped outer circumferential surface which is matched with the mounting hole of the housing to fix the steering screw in the circumferential direction and limit the rotation of the steering screw.

4. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 2, characterized in that The sleeve element comprises an end surface step, an inner circumferential surface axial groove and an outer circumferential surface plane, wherein the end surface step is in contact with the flange edge and the protrusion of the retaining element to realize the axial positioning of the retaining element in the sleeve, the inner circumferential surface axial groove is used for accommodating the rolling element, and the outer circumferential surface plane is in contact with the housing to limit the rotation of the sleeve element relative to the housing.

5. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 2, characterized in that The sleeve element further comprises an outer circumferential surface circumferential groove, and an O-ring is installed in the outer circumferential surface circumferential groove to compensate for the assembly gap between the outer circumferential surface of the sleeve element and the housing.

6. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 2, characterized in that The material of the retaining element is nylon.

7. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 6, characterized in that The steering screw is designed with a plurality of circumferentially uniformly distributed axial grooves with arc-shaped cross sections in the support area of the non-servo end, the axial grooves are used for accommodating the rolling elements, the shape of the groove cross section is matched with the rolling element, the length of the groove can cover the stroke range of the steering screw, and the depth of the groove is designed to cover one third of the cross-sectional width of the rolling element.

8. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 7, characterized in that The materials of the sleeve element and the rolling element are bearing steel.

9. A device for supporting and securing a steering screw for a steer-by-wire system according to claim 4, characterized in that ​ 10. A device for supporting and securing a steering screw for a steer-by-wire system according to one of claims 2 to 9, characterized in that ​

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