Rear wheel steering gear and vehicle

Abstract

The utility model provides a rear wheel steering gear and a vehicle. The rear wheel steering gear comprises a driving device, a nut, a lead screw, a displacement sensor, an induction piece and a shaft sleeve. A shell of the rear wheel steering gear is used for containing a nut and a lead screw, the lead screw is assembled in the nut, a driving device is used for driving the nut to rotate, the nut drives the lead screw to generate displacement in the axial direction of the lead screw, and the lead screw is used for driving wheels of a vehicle to deflect. The shell is used for containing the induction piece, the induction piece is fixed to the lead screw through a screw, the displacement sensor is fixed to the upper portion of the induction piece in the radial direction of the lead screw, and the displacement sensor is used for detecting the displacement amount of the lead screw through the induction piece. A shaft sleeve is arranged between the lead screw and the shell in the radial direction of the lead screw and comprises a limiting structure, and the limiting structure is used for limiting the lead screw to rotate when the lead screw moves in the axial direction of the lead screw and driving the induction piece to rotate. According to the rear wheel steering gear, the shaft sleeve with the limiting structure is used for limiting rotation of the lead screw relative to the rear wheel steering gear shell, internal interference is avoided, and noise is reduced.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, specifically to a rear-wheel steering system and a vehicle. Background Technology

[0002] The rear-wheel steering system is used to control the steering of the vehicle's rear wheels, thereby reducing the vehicle's turning radius and improving stability. To save interior space, the size of the rear-wheel steering system needs to be controlled. Due to its complex internal structure, the rear-wheel steering system may generate friction and noise during operation, affecting the overall vehicle noise, vibration, and harshness (NVH) performance. Utility Model Content

[0003] This application provides a rear-wheel steering system and a vehicle. A bushing with a limiting structure restricts the rotation of the lead screw relative to the rear-wheel steering system housing during axial movement of the lead screw, thereby preventing internal interference of the rear-wheel steering system and reducing noise.

[0004] In a first aspect, this application provides a rear-wheel steering system, comprising a drive unit, a nut, a lead screw, a displacement sensor, a sensing element, and a bushing. The housing of the rear-wheel steering system accommodates the nut and the lead screw, with the lead screw mounted within the nut. The drive unit drives the nut to rotate, causing the nut to displace the lead screw axially. The lead screw then deflects the vehicle's wheels. The housing also accommodates the sensing element, which is fixed to the lead screw by a screw. The displacement sensor is fixed radially above the sensing element and detects the amount of displacement of the lead screw through the sensing element. A bushing is located radially between the lead screw and the housing. The bushing includes a limiting structure that restricts rotation of the lead screw during axial movement and also restricts the rotation of the sensing element caused by the lead screw.

[0005] The rear-wheel steering system provided in this application uses a drive unit to rotate a nut, which in turn causes the lead screw to move axially along the lead screw and thus deflect the vehicle's wheels. The rear-wheel steering system also uses a displacement sensor to monitor a sensing element that moves synchronously with the lead screw, thereby detecting the amount of axial displacement of the lead screw and forming a closed-loop control of the wheel deflection.

[0006] The lead screw is rotatably connected to the rear wheel steering gear housing via a bushing. The bushing, through a limiting structure, restricts the rotation of the lead screw relative to the housing during axial displacement, thereby limiting the synchronous rotation of the sensor fixed to the lead screw within the housing. The position of the sensor relative to the housing along the axial direction of the lead screw is relatively fixed, thus avoiding noise generated by the sensor rubbing against the housing during axial displacement with the lead screw. The rear wheel steering gear provided in this application improves the vehicle's NVH performance by reducing internal friction.

[0007] In one implementation, the limiting structure includes a first limiting surface and a second limiting surface, both of which are planes. The first limiting surface is located on the inner circumferential surface of the bushing, and the second limiting surface is located on the outer circumferential surface of the bushing. Along the circumferential direction of the lead screw, the first limiting surface abuts against the lead screw and the second limiting surface abuts against the housing. The first and second limiting surfaces are used to limit the rotation of the lead screw when it moves along the axial direction of the lead screw.

[0008] In this implementation, when the lead screw moves axially, the first limiting surface abuts against the lead screw circumferentially to restrict the bushing from rotating relative to the lead screw. The second limiting surface abuts against the housing circumferentially to restrict the bushing from rotating relative to the housing. Thus, the bushing, through the limiting structure, restricts the lead screw from rotating relative to the housing during axial displacement.

[0009] In one implementation, along the radial direction of the lead screw, the distance between the first limiting surface and the center surface of the lead screw is less than the inner circumferential radius of the bushing, and the distance between the second limiting surface and the center surface of the lead screw is less than the outer circumferential radius of the bushing.

[0010] In this implementation, the first limiting surface is used to embed into the outer circumferential surface of the lead screw in the radial direction to form a circumferential abutment, and the housing is used to embed into the outer circumferential surface of the bushing in the radial direction to form a circumferential abutment. The contact area between the first limiting surface and the outer circumferential surface of the lead screw, and the contact area between the second limiting surface and the housing are relatively large, which improves the reliability of the limiting structure.

[0011] One implementation method involves the first limiting surface being parallel to the second limiting surface.

[0012] In this implementation, the inner and outer circumferential surfaces of the bushing are parallel, and the first and second limiting surfaces are parallel. The thickness of the bushing is relatively uniform along the circumferential direction of the lead screw, which facilitates the one-time stamping of the bushing and reduces costs, and also facilitates installation.

[0013] One implementation includes a limiting structure comprising a third limiting surface and a fourth limiting surface, wherein the third limiting surface and the first limiting surface are symmetrically arranged with respect to the central plane of the lead screw, and the fourth limiting surface and the second limiting surface are symmetrically arranged with respect to the central plane of the lead screw.

[0014] In this implementation, the third and first limiting surfaces abut against the outer circumferential surface of the lead screw from both sides, improving the reliability of the circumferential contact between the bushing and the lead screw. The fourth and second limiting surfaces abut against the housing from both sides of the lead screw, further improving the reliability of the circumferential contact between the bushing and the housing.

[0015] In one implementation, the lengths of the first and second limiting surfaces along the axial direction of the lead screw are respectively less than or equal to the length of the bushing.

[0016] In this implementation, the bushing is fixed relative to the housing, and the lead screw undergoes axial displacement within the bushing. The axial length of either the first or second limiting surface being less than the axial length of the bushing does not affect the limiting effect of the limiting structure. If the axial length of either the first or second limiting surface is equal to the axial length of the bushing, the contact area between the limiting structure and the lead screw and the housing can be increased, thereby improving the reliability of the limiting structure. By limiting the axial length of the first and second limiting surfaces to be less than or equal to the length of the bushing, it is possible to effectively ensure that the bushing restricts the rotation of the lead screw relative to the housing, while also reducing processing and lowering costs. In one implementation, the limiting structure includes a first limiting structure and a second limiting structure, which extend radially along the lead screw. The first limiting structure is located on the inner circumferential surface of the bushing, and the second limiting structure is located on the outer circumferential surface of the bushing. Along the circumferential direction of the lead screw, the first limiting structure abuts against the lead screw, and the second limiting structure abuts against the housing. The first and second limiting structures are used to restrict the rotation of the lead screw when it moves axially along the lead screw.

[0017] In this implementation, the first limiting structure and the second limiting structure extending radially along the lead screw can be respectively engaged with the lead screw and the housing in the circumferential direction, which can also limit the rotation of the lead screw relative to the housing during the axial displacement process.

[0018] In one implementation, a first limiting structure includes a first protrusion, and a second limiting structure includes a second protrusion. The first protrusion protrudes radially from the lead screw towards a direction close to the center plane of the lead screw, and the second protrusion protrudes radially from the lead screw away from the center plane of the lead screw. The first protrusion is used to embed into the lead screw and abut against the lead screw circumferentially, and the second protrusion is used to embed into the housing and abut against the housing circumferentially.

[0019] In one implementation, a first limiting structure includes a first groove, and a second limiting structure includes a second groove. The first groove is recessed radially away from the center plane of the lead screw, and the second groove is recessed radially towards the center plane of the lead screw. The lead screw is used to engage with the first groove and abut against the bushing circumferentially, and the housing is used to engage with the second groove and abut against the bushing circumferentially.

[0020] In one implementation, the first and second limiting structures extend in the same direction along the radial direction of the lead screw. The thickness of the circumferential bushing along the lead screw is relatively uniform, which facilitates the machining and forming of the bushing and reduces costs.

[0021] In one implementation, the length of the bushing along the axial direction of the lead screw is greater than the diameter of the inner circumferential surface of the bushing along the radial direction of the lead screw.

[0022] In this implementation, the axial length of the bushing is larger than the outer diameter of the lead screw, which can improve the guiding effect of the bushing on the lead screw and ensure that the lead screw moves smoothly along the axial direction.

[0023] In one implementation, the rear wheel steering gear includes two bushings, which are respectively sleeved on both ends of the lead screw along the axial direction of the lead screw, and the limiting structures of the two bushings do not overlap along the axial direction of the lead screw.

[0024] In this implementation, the housing reliably supports the lead screw via two bushings. The projections of the limiting structures of the two bushings onto the axial direction of the lead screw do not coincide, the directions of the gaps between the two limiting structures and the lead screw are different, and the directions of the gaps between the two limiting structures and the housing are also different. This helps to improve the stress on the lead screw and enhance the reliability of the limiting structures.

[0025] In one implementation, the housing includes a receiving groove for accommodating a portion of a lead screw, a displacement sensor, a screw, and a sensing element. Along the circumference of the lead screw, a first gap is included between the limiting structure and the lead screw, and a second gap is included between the limiting structure and the housing. The sum of the first and second gaps is used to limit contact between the sensing element and the wall of the receiving groove.

[0026] In this implementation, the first clearance ensures that the lead screw does not interfere with the sliding within the housing, while the second clearance allows the shaft sleeve to be fitted into the housing. The lead screw can rotate slightly within the range of the sum of the first and second clearances during axial sliding. By limiting the sum of the first and second clearances, the rotation angle of the lead screw can be limited, preventing the sensing element from contacting and rubbing against the wall of the receiving groove.

[0027] In one implementation, the screw along the arrangement direction of the displacement sensor and the sensing element includes a section extending into the lead screw, and the section of the screw extending into the lead screw along the radial direction does not extend beyond the surface of the lead screw.

[0028] In this implementation, one end of the screw is completely contained within the lead screw, preventing the end of the screw from contacting the bottom or wall of the receiving groove and causing friction.

[0029] In one implementation, a screw extends radially into a portion of the lead screw beyond the surface of the lead screw, and the sum of a first gap and a second gap is used to limit contact between the portion of the screw extending into the lead screw beyond the surface of the lead screw and the wall of the receiving groove.

[0030] In this implementation, one end of the screw extends beyond the lead screw, and the mating dimension between the screw and the lead screw is longer to improve reliability. By limiting the sum of the first clearance and the second clearance, the rotation angle of the screw with the lead screw can be limited, preventing the end of the screw from contacting and rubbing against the wall of the receiving groove after it extends beyond the lead screw.

[0031] In one implementation, the sensing element includes a plastic part, the other end of a screw for fixing the plastic part, the plastic part for supporting the sensing plate of the sensing element, and a displacement sensor for detecting the axial displacement of the lead screw through the sensing plate.

[0032] In this implementation, the plastic component can reduce the weight of the sensing component and ensure that the sensing element slides synchronously with the lead screw, thereby improving the detection accuracy of the displacement sensor.

[0033] In one implementation, the circumferential plastic part along the lead screw includes two opposite sidewalls, each sidewall for fixing a film layer, the film layer being made of at least one of nitrile rubber, polysulfide rubber, or butyl rubber.

[0034] In this implementation, the friction coefficient of the material is relatively small. If the rotation angle is too large during the axial displacement of the lead screw, the film layer can abut against the plastic part and the wall of the receiving groove and reduce the noise generated by friction.

[0035] In one implementation, the sidewall includes multiple grooves for receiving grease.

[0036] In this implementation, if the rotation angle is unexpectedly too large during the axial displacement of the lead screw, the grease in the groove can reduce the noise generated by friction.

[0037] One implementation involves circular groove openings, with the grooves arranged at intervals.

[0038] One implementation involves a rhomboid groove opening, with each groove connected sequentially.

[0039] One implementation involves arranging the grooves at intervals or sequentially connecting them along the axial direction of the lead screw.

[0040] Secondly, this application provides a vehicle comprising two rear wheels and a rear-wheel steering system provided in any of the above implementations. The two rear wheels are located on opposite sides of the vehicle, and each rear-wheel steering system is used to drive the rear wheel on one side of the vehicle to deflect. Because the vehicle provided in this application employs the aforementioned rear-wheel steering system, its interior space is relatively large and its NVH performance is better.

[0041] In one implementation, the vehicle includes front wheels and a front wheel steering unit, the housing of the front wheel steering unit for accommodating another lead screw, the other lead screw for receiving drive and generating displacement along the axial direction of the other lead screw, the other lead screw for driving the front wheels to deflect, and another bushing between the other lead screw and the housing of the front wheel steering unit, the limiting structure of the other bushing for limiting the rotation generated when the other lead screw moves axially.

[0042] In this implementation, the front wheel steering gear of the vehicle includes another bushing, which also limits the rotation of the lead screw of the front wheel steering gear relative to the housing of the front wheel steering gear, thereby further improving the NVH performance of the vehicle's front wheel steering gear. Attached Figure Description

[0043] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the vehicle architecture provided in one embodiment of this application;

[0045] Figure 2 This is a schematic diagram of the vehicle architecture provided in one embodiment of this application;

[0046] Figure 3 This is a schematic diagram of the structure of a rear wheel steering system provided in one embodiment of this application;

[0047] Figure 4 This is an exploded view of the rear wheel steering system provided in one embodiment of this application;

[0048] Figure 5 This is a cross-sectional structural schematic diagram of a rear wheel steering system provided in one embodiment of this application;

[0049] Figure 6 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0050] Figure 7 This is a partially exploded structural diagram of the rear wheel steering system provided in one embodiment of this application;

[0051] Figure 8 This is a partial cross-sectional structural diagram of the rear wheel steering system provided in one embodiment of this application;

[0052] Figure 9 This is a partial cross-sectional structural diagram of the rear wheel steering system provided in one embodiment of this application;

[0053] Figure 10 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0054] Figure 11 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0055] Figure 12 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0056] Figure 13 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0057] Figure 14 This is a cross-sectional structural schematic diagram of a rear wheel steering system provided in one embodiment of this application;

[0058] Figure 15 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0059] Figure 16 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0060] Figure 17 This is a partial cross-sectional structural diagram of the rear wheel steering system provided in one embodiment of this application;

[0061] Figure 18 This is a partial cross-sectional structural diagram of the rear wheel steering system provided in one embodiment of this application;

[0062] Figure 19 This is a cross-sectional view of one side of the rear wheel steering system provided in one embodiment of this application;

[0063] Figure 20 This is a cross-sectional structural diagram of the rear wheel steering system provided in one embodiment of this application from another side view.

[0064] Figure 21 This is a cross-sectional structural schematic diagram of a rear wheel steering system provided in one embodiment of this application;

[0065] Figure 22 A cross-sectional structural schematic diagram of a rear wheel steering system provided in one embodiment of this application;

[0066] Figure 23 This is a partially exploded structural diagram of the rear wheel steering system provided in one embodiment of this application;

[0067] Figure 24 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0068] Figure 25 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0069] Figure 26 This is a partial cross-sectional structural diagram of a vehicle provided in one embodiment of this application;

[0070] Figure 27 This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0071] Figure 28This is a partial structural schematic diagram of the rear wheel steering system provided in one embodiment of this application;

[0072] Figure 29 This is a partially enlarged schematic diagram of a rear wheel steering system provided in one embodiment of this application.

[0073] Reference numerals: 1000-Vehicle; 1001-Frame; 1002-Rear wheel; 1003-Front wheel; 1004-Fork; 500-Front wheel steering gear; 100-Rear wheel steering gear; 10-Drive unit; 20-Nut; 30-Lead screw; 31-First limiting mating surface; 32-Third limiting mating surface; 33-First limiting groove; 34-First limiting protrusion; 40-Housing; 41-Receiving groove; 411-Axial groove wall; 4111-Positioning hole; 412-Radial groove wall; 42-Cover plate; 43-Second limiting mating surface; 44-Fourth limiting mating surface; 47-Radial protrusion; 48-Ventilation groove; 50-Displacement Sensor; 60-Sensing element; 61-Plastic part; 62-Sensing sheet; 63-Side wall; 64-Film layer; 65-Groove; 70-Screw; 71-First segment; 72-Second segment; 80-Busset; 81-First arc surface; 82-First plane; 83-Second arc surface; 84-Second plane; 90-Limiting structure; 91-First limiting surface; 92-Second limiting surface; 93-Third limiting surface; 94-Fourth limiting surface; 95-First protrusion; 96-Second protrusion; 97-First groove; 98-Second groove; 001-First radial direction; 002-Second radial direction; 003-First gap; 004-Second gap. Detailed Implementation

[0074] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0075] This application provides a rear-wheel steering system, which includes a drive unit, a nut, a lead screw, a displacement sensor, a sensing element, and a bushing. The housing of the rear-wheel steering system accommodates the nut and the lead screw, with the lead screw mounted within the nut. The drive unit drives the nut to rotate, causing the nut to displace the lead screw along its axial direction. The lead screw then deflects the vehicle's wheels. The housing also accommodates the sensing element, which is fixed to the lead screw by a screw. The displacement sensor is fixed radially above the sensing element and detects the amount of displacement of the lead screw through the sensing element. A bushing is located radially between the lead screw and the housing. The bushing includes a limiting structure to restrict the rotation of the lead screw during axial movement, thus limiting the rotation of the sensing element.

[0076] The rear-wheel steering system provided in this application restricts the rotation of the lead screw relative to the housing during axial displacement through a bushing limiting structure, thereby preventing noise generated by the sensing element due to friction with the housing during the axial displacement of the lead screw. In other words, it improves the vehicle's NVH performance by reducing internal friction.

[0077] This application provides a vehicle comprising two rear wheels and the aforementioned rear-wheel steering system. The two rear wheels are located on opposite sides of the vehicle, and each rear-wheel steering system is used to drive the rear wheel on one side of the vehicle to turn. Because the vehicle provided in this application employs the aforementioned rear-wheel steering system, its interior space is relatively large and its NVH performance is better.

[0078] Please see Figure 1 , Figure 1 This is a schematic diagram of the architecture of a vehicle 1000 provided in one embodiment of this application.

[0079] like Figure 1 As shown, the vehicle 1000 provided in this application includes a rear-wheel steering unit 100, which is fixed to the frame 1001 and is throttle-connected to one or more rear wheels 1002 of the vehicle 1000. The rear-wheel steering unit 100 is used to drive one or more rear wheels 1002 of the vehicle 1000 to turn, thereby increasing the range of steering angle control of the vehicle 1000 and reducing the occurrence of understeer or oversteer of the vehicle 1000.

[0080] In one embodiment, the vehicle 1000 provided in this application includes a front wheel steering unit 500, which is fixed to the frame 1001 and is connected in transmission to one or more front wheels 1003 of the vehicle 1000. The front wheel steering unit 500 is used to drive one or more front wheels 1003 of the vehicle 1000 to turn, thereby realizing the steering function of the vehicle 1000.

[0081] For example, in some scenarios where vehicle 1000 needs to turn or make a U-turn with a small turning radius, the front wheels 1003 and rear wheels 1002 of vehicle 1000 can be controlled to turn in opposite directions by the front wheel steering unit 500 and the rear wheel steering unit 100, thereby reducing the turning radius and improving the agility of vehicle 1000. In other scenarios where vehicle 1000 needs to corner at a certain speed, the front wheels 1003 and rear wheels 1002 of vehicle 1000 can be controlled to turn in the same direction by the front wheel steering unit 500 and the rear wheel steering unit 100, thereby reducing the sideslip angle of vehicle 1000, reducing the steady-state overshoot of vehicle 1000's yaw rate, and thus enhancing the handling stability of vehicle 1000.

[0082] In one embodiment, the vehicle 1000 provided in this application has two rear wheels 1002 and two rear wheel steering units 100, with the two rear wheels 1002 positioned on either side of the vehicle 1000. Each rear wheel steering unit 100 is used for transmission connection with one rear wheel 1002 of the vehicle 1000 and for driving one rear wheel 1002 of the vehicle 1000 to change steering. It should be noted that the number of rear wheels 1002 and rear wheel steering units 100 of the vehicle 1000 provided in this application includes, but is not limited to, two. For example, please refer to... Figure 2 , Figure 2 This is a schematic diagram of the architecture of a vehicle 1000 provided in one embodiment of this application. In another embodiment, the vehicle 1000 provided in this application includes two rear wheels 1002 and a rear wheel steering unit 100, with the two rear wheels 1002 positioned on both sides of the vehicle 1000. The rear wheel steering unit 100 is used for transmission connection with the two rear wheels 1002 on both sides of the vehicle 1000 and for driving the two rear wheels 1002 to change direction.

[0083] Please refer to the above. Figures 3 to 5 ,in Figure 3 This is a schematic diagram of the structure of the rear wheel steering system 100 provided in one embodiment of this application; Figure 4 This is an exploded structural diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 5 This is a cross-sectional structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0084] like Figures 3 to 5 As shown, the rear wheel steering system 100 provided in this application includes a drive unit 10, a nut 20, and a lead screw 30. The drive unit 10 is used to drive the nut 20 and provide driving force to rotate the nut 20. The nut 20 is sleeved on the outer circumferential surface of the lead screw 30 and is used for meshing and driving with the lead screw 30. That is, the outer circumferential surface of the nut 20 is used for driving the drive unit 10, and the inner circumferential surface of the nut 20 is used for meshing with the outer circumferential surface of the lead screw 30. The nut 20 is used to receive the driving rotation of the drive unit 10 and drive the lead screw 30 to produce displacement along the axial direction of the lead screw 30. The lead screw 30 is used to be assembled in the nut 20 and is used to receive the drive from the drive unit 10 through the nut 20. The lead screw 30 extends along an axial direction parallel to the rear wheel 1002 and is used for driving the rear wheel 1002 of the vehicle 1000. The lead screw 30 is used to convert the rotational motion of the nut 20 into a linear displacement along the axis of the lead screw 30 and output it to the rear wheel 1002, so as to drive the rear wheel 1002 of the vehicle 1000 to deflect relative to the frame 1001, thereby realizing the steering of the rear wheel 1002.

[0085] In one embodiment, the rear wheel steering gear 100 provided in this application further includes a reducer (not shown in the figure). The reducer is used to drive the drive device 10 and the nut 20. The reducer is also used to adjust the driving force and torque output by the drive device 10 and transmit the adjusted driving force to the nut 20. For example, the reducer is used to reduce the rotational speed of the screw sleeve and amplify the driving force output by the drive device 10 to ensure that the lead screw 30 can generate a lateral displacement under the drive of the screw sleeve, thereby ensuring that the lead screw 30 can reliably drive the rear wheel 1002 to deflect and achieve steering.

[0086] In one embodiment, the rear wheel steering system 100 provided in this application further includes a fork 1004, which is used to drive the lead screw 30 and the rear wheel 1002. That is, the output end of the lead screw 30 is driven to the rear wheel 1002 of the vehicle 1000 through the fork 1004. When the rear wheel 1002 of the vehicle 1000 provided in this application needs to turn, the drive device 10 drives the threaded sleeve to rotate, and drives the lead screw 30 to move along its own axial direction, so as to move the fork 1004, thereby causing the rear wheel 1002 to deflect relative to the frame 1001, thus realizing the steering of the rear wheel 1002.

[0087] In one embodiment, a plurality of balls (not shown) are also included between the inner circumferential surface of the nut 20 and the outer circumferential surface of the lead screw 30. The plurality of balls are used to reduce the friction between the screw sleeve and the lead screw 30, so as to improve the transmission efficiency of the rear wheel steering gear 100 of this application.

[0088] The rear wheel steering system 100 of this application also includes a housing 40, a displacement sensor 50, and a sensing element 60. The housing 40 is used to fix itself to the vehicle frame 1001 and also to house the nut 20, the lead screw 30, and the sensing element 60. The lead screw 30 is rotatably connected to the housing 40 of the rear wheel steering system 100 via a bushing 80. Specifically, along the radial direction of the lead screw 30, a bushing 80 is included between the lead screw 30 and the housing 40. The bushing 80 is sleeved on the outer circumferential surface of the lead screw 30 and fits within the positioning hole 4111 of the housing 40. The lead screw 30 is supported on the housing 40 by the bushing 80 and is movable relative to the housing 40.

[0089] For example, a bushing 80 is fitted onto the end of the lead screw 30 that is relatively close to the rear wheel 1002. The end of the lead screw 30 that is relatively close to the rear wheel 1002 passes through the bushing 80 and is drively connected to the rear wheel 1002. A sensor 60 is fixed to the lead screw 30 by a screw 70 and is used to move relative to the housing 40 along the axial direction of the lead screw 30 as the lead screw 30 moves. A displacement sensor 50 is fixed to the housing 40 and is fixed radially above the sensor 60 along the lead screw 30. The displacement sensor 50 is used to detect the amount of displacement of the lead screw 30 relative to the housing 40 by detecting the movement of the sensor 60. The rear wheel steering system 100 provided in this application detects the amount of axial displacement of the lead screw 30 by detecting the sensor 60 that moves synchronously with the lead screw 30 through the displacement sensor 50, thereby forming a closed-loop control of the wheel deflection.

[0090] The bushing 80 includes a limiting structure 90, which restricts the rotation of the lead screw 30 during axial movement and also restricts the rotation of the sensing element 60 driven by the lead screw 30. In the prior art, during the process where the drive device 10 drives the nut 20 to rotate, and the nut 20 drives the lead screw 30 to move axially, the lead screw 30 may generate a certain circumferential force with the rotation of the nut 20. This can cause the lead screw 30 to move circumferentially relative to the housing 40, and consequently, the sensing element 60 may move circumferentially relative to the housing 40, making it easy for the sensing element 60 to interfere with the housing 40. The bushing 80 of this application, through the limiting structure 90, restricts the rotation of the lead screw 30 relative to the housing 40 during axial displacement, thereby limiting the synchronous rotation of the sensing element 60 fixed to the lead screw 30 within the housing 40. Along the axial direction of the lead screw 30, the position of the sensing element 60 relative to the housing 40 is relatively fixed, thus avoiding noise generated by the sensing element 60 rubbing against the housing 40 during axial displacement with the lead screw 30. The rear-wheel steering system 100 provided in this application improves the NVH performance of the vehicle 1000 by reducing internal friction.

[0091] Please refer to the above. Figures 6 to 8 ,in Figure 6 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 7 This is a partially exploded structural diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 8 This is a partial cross-sectional structural diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0092] In one embodiment, the housing 40 includes a receiving groove 41, which includes a pair of axial groove walls 411 and a pair of radial groove walls 412. The pair of axial groove walls 411 are arranged opposite each other along the axial direction of the lead screw 30, and the pair of radial groove walls 412 are arranged opposite each other along the radial direction of the lead screw 30. Each axial groove wall 411 includes a positioning hole 4111, the axis of which coincides with the axial direction of the lead screw 30. A bushing 80 is fixed within the positioning hole 4111. The lead screw 30 is partially received within the receiving groove 41, and along the axial direction of the lead screw 30, its opposite ends are respectively used to pass through a positioning hole 4111. Exemplarily, the end of the lead screw 30 closest to the rear wheel 1002 extends into the bushing 80, and the lead screw 30 is supported on the housing 40 by the bushing 80 and is movable relative to the housing 40. In other embodiments, the end of the lead screw 30 closest to the drive device 10 may extend into the bushing 80, which is not particularly limited in this application. The sensing element 60 is fixed to the lead screw 30 by screws 70 and moves relative to the housing 40 with the lead screw 30. The displacement sensor 50 is fixed to the housing 40 and spaced apart from the lead screw 30. The displacement sensor 50 and the sensing element 60 are arranged radially opposite each other along the lead screw 30, and the arrangement direction of the displacement sensor 50 and the sensing element 60 is perpendicular to the arrangement direction of a pair of radial groove walls 412. The sensing element 60 extends towards the displacement sensor 50 through the gap between the pair of radial groove walls 412. That is, the gap between the pair of radial groove walls 412 is used to accommodate the sensing element 60 and allow the sensing element 60 to move with the lead screw 30. The limiting structure 90 of the bushing 80 is used to limit the relative rotation between the lead screw 30 and the housing 40, thereby limiting the relative displacement between the sensing element 60 and the radial groove wall 412, avoiding the sensing element 60 from contacting the radial groove wall 412 and generating noise during the axial displacement of the lead screw 30, thus improving the NVH performance of the entire vehicle.

[0093] In one embodiment, the housing 40 includes a cover plate 42 for covering the opening of the receiving groove 41, and the displacement sensor 50 is fixed to the inner wall of the cover plate 42 facing the lead screw 30.

[0094] In one embodiment, the central axis of the bushing 80 coincides with the central axis of the lead screw 30.

[0095] In one embodiment, the central axis of the bushing 80, the central axis of the lead screw 30, and the central axis of the positioning hole 4111 coincide.

[0096] In one embodiment, the limiting structure 90 includes two limiting surfaces. The two limiting surfaces are respectively used to abut against the outer peripheral surface of the lead screw 30 and the inner wall of the positioning hole 4111 of the housing 40 to limit the rotation of the lead screw 30 relative to the housing 40.

[0097] Please refer to the above. Figures 9 to 12 ,in Figure 9 This is a partial cross-sectional structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 10 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 11 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 12 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0098] For ease of explanation, this application defines the two limiting surfaces as a first limiting surface 91 and a second limiting surface 92, respectively. The first limiting surface 91 is located on the inner circumferential surface of the bushing 80, and the second limiting surface 92 is located on the outer circumferential surface of the bushing 80. Along the circumferential direction of the lead screw 30, the first limiting surface 91 is used to abut against the lead screw 30, and the second limiting surface 92 is used to abut against the housing 40. The first limiting surface 91 and the second limiting surface 92 are used to restrict the lead screw 30 from rotating when it moves along the axial direction of the lead screw 30. Exemplarily, the outer circumferential surface of the lead screw 30 includes a first limiting mating surface 31, and the inner wall of the positioning hole 4111 of the housing 40 includes a second limiting mating surface 43. The first limiting mating surface 31 is used to abut against the first limiting surface 91, and the second limiting mating surface 43 is used to abut against the second limiting surface 92. That is, the first limiting mating surface 31 and the first limiting surface 91 cooperate with each other to constrain the circumferential movement of the lead screw 30 relative to the bushing 80; the second limiting mating surface 43 and the second limiting surface 92 cooperate with each other to constrain the circumferential movement of the bushing 80 relative to the housing 40.

[0099] In this embodiment, when the lead screw 30 moves along its own axial direction, the first limiting surface 91 abuts against the lead screw 30 along the circumferential direction to restrict the rotation of the bushing 80 relative to the lead screw 30; the second limiting surface 92 abuts against the inner wall of the positioning hole 4111 of the housing 40 along the circumferential direction to restrict the rotation of the bushing 80 relative to the housing 40. Thus, the bushing 80 is restricted by the limiting structure 90 to prevent the lead screw 30 from rotating relative to the housing 40 during its axial displacement. Furthermore, the bushing 80 is limited by surface-to-surface interaction with the lead screw 30 and the housing 40, effectively preventing the lead screw 30 from rotating relative to the housing 40 while also reducing the machining and assembly difficulties of the lead screw 30, bushing 80, and housing 40.

[0100] It should be noted that in the above embodiments, the number of limiting surfaces is only an example, that is, the limiting structure 90 of this application includes, but is not limited to, two limiting surfaces. For example, in another embodiment, the number of limiting surfaces can be multiple, with some of the limiting surfaces located on the inner circumferential surface of the bushing 80 and arranged at intervals along the circumference of the lead screw 30; another portion of the limiting surfaces are located on the outer circumferential surface of the bushing 80 and arranged at intervals along the circumferential direction of the lead screw 30. The cooperation of multiple limiting surfaces can also restrict the rotation of the lead screw 30 relative to the housing 40.

[0101] In one embodiment, both the first limiting surface 91 and the second limiting surface 92 are planar.

[0102] In one embodiment, both the first limiting mating surface 31 and the second limiting mating surface 43 are planar.

[0103] In the above embodiments, by setting the first limiting surface 91, the second limiting surface 92, the first limiting mating surface 31 and the second limiting mating surface 43 as planes, it is beneficial to process and assemble the lead screw 30, the bushing 80 and the housing 40.

[0104] It should be noted that the first limiting surface 91 and the second limiting surface 92 in the above embodiments are both planar and are only used as an example. That is, the shape of the first limiting surface 91 and the second limiting surface 92 in this application includes but is not limited to a planar surface. For example, they can also be curved surfaces or irregular surfaces.

[0105] Please refer to the above. Figure 13 , Figure 13 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0106] In one embodiment, along the radial direction of the lead screw 30, the distance between the first limiting surface 91 and the center surface of the lead screw 30 is less than the inner circumferential radius of the bushing 80, and the distance between the second limiting surface 92 and the center surface of the lead screw 30 is less than the outer circumferential radius of the bushing 80. The center surface of the lead screw 30 is a plane passing through the central axis of the lead screw 30. For ease of explanation, this application defines the inner circumferential radius of the bushing 80 as r1, the outer circumferential radius of the bushing 80 as r2; the distance between the first limiting surface 91 and the center surface of the lead screw 30 as d1, and the distance between the second limiting surface 92 and the center surface of the lead screw 30 as d2. Where d1 < r1; d2 < r2.

[0107] Specifically, the first limiting surface 91 is closer to the center plane of the lead screw 30 relative to the inner circumferential surface of the bushing 80, and the first limiting surface 91 is used to radially embed into the outer circumferential surface of the lead screw 30 to form a circumferential abutment. The second limiting surface 92 is closer to the center plane of the lead screw 30 relative to the outer circumferential surface of the bushing 80, and the housing 40 is used to radially embed into the outer circumferential surface of the bushing 80 to form a circumferential abutment. In this embodiment, the contact area between the first limiting surface 91 and the outer circumferential surface of the lead screw 30, and the contact area between the second limiting surface 92 and the housing 40 are relatively large, which is beneficial to improving the reliability of the limiting.

[0108] In one embodiment, along the radial direction of the lead screw 30, the first limiting surface 91 and the second limiting surface 92 are located on the same side of the central plane of the lead screw 30. The first limiting surface 91 and the second limiting surface 92 are parallel. In this embodiment, the inner circumferential surface of the bushing 80 is parallel to the outer circumferential surface of the bushing 80, and the first limiting surface 91 and the second limiting surface 92 are parallel. That is, the inner contour formed by the inner circumferential surface of the bushing 80 and the first limiting surface 91 is the same as the outer contour formed by the outer circumferential surface of the bushing 80 and the second limiting surface 92, but the distances from the inner contour and the outer contour to the central axis of the lead screw 30 are different. Thus, the thickness of the bushing 80 is relatively uniform along the circumference of the lead screw 30, which facilitates the one-time stamping forming of the bushing 80 and reduces costs, and also facilitates installation.

[0109] It should be noted that the fact that the first limiting surface 91 and the second limiting surface 92 are located on the same side of the center plane of the lead screw 30 in the above embodiment is only an example. That is, in other embodiments of this application, the first limiting surface 91 and the second limiting surface 92 may include other arrangements. For example, the first limiting surface 91 and the second limiting surface 92 are arranged at intervals along the circumference of the lead screw 30, and the first limiting surface 91 and the second limiting surface 92 are located on different sides of the lead screw 30, which can also achieve the effect of restricting the rotation of the lead screw 30 relative to the housing 40.

[0110] Please refer to the above. Figures 14 to 16 ,in Figure 14 This is a cross-sectional structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 15 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 16 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0111] In one embodiment, the limiting structure 90 has four limiting surfaces. Two of these limiting surfaces are the first limiting surface 91 and the second limiting surface 92. For ease of explanation, the other two limiting surfaces are defined as the third limiting surface 93 and the fourth limiting surface 94. The third limiting surface 93 is located on the inner circumferential surface of the bushing 80, and the fourth limiting surface 94 is located on the outer circumferential surface of the bushing 80. Along the circumferential direction of the lead screw 30, the third limiting surface 93 is used to abut against the lead screw 30, and the fourth limiting surface 94 is used to abut against the housing 40. The third limiting surface 93 and the fourth limiting surface 94 are used to cooperate with the first limiting surface 91 and the second limiting surface 92 to restrict the lead screw 30 from rotating when it moves along the axis of the lead screw 30. Exemplarily, the outer circumferential surface of the lead screw 30 includes the third limiting mating surface 32, and the inner wall of the positioning hole 4111 of the housing 40 includes the fourth limiting mating surface 44. The third limiting mating surface 32 is used to abut against the third limiting surface 93, and the fourth limiting mating surface 44 is used to abut against the fourth limiting surface 94. That is, the third limiting mating surface 32 and the third limiting surface 93 cooperate with each other to further constrain the circumferential movement of the lead screw 30 relative to the housing 40; the fourth limiting mating surface 44 and the fourth limiting surface 94 cooperate with each other to further constrain the circumferential movement of the bushing 80 relative to the housing 40.

[0112] In this embodiment, when the lead screw 30 moves along its own axial direction, the third limiting surface 93 abuts against the lead screw 30 along the circumferential direction, in conjunction with the first limiting surface 91 to further restrict the rotation of the bushing 80 relative to the lead screw 30; the fourth limiting surface 94 abuts against the inner wall of the positioning hole 4111 of the housing 40 along the circumferential direction, in conjunction with the second limiting surface 92 to further restrict the rotation of the bushing 80 relative to the housing 40. That is, the third limiting surface 93 and the first limiting surface 91 abut against the outer circumferential surface of the lead screw 30 from both sides, improving the reliability of the bushing 80 abutting against the lead screw 30 along the circumferential direction; the fourth limiting surface 94 and the second limiting surface 92 abut against the housing 40 from both sides of the lead screw 30, improving the reliability of the bushing 80 abutting against the housing 40 along the circumferential direction. Thus, the bushing 80, through each limiting surface, can improve the reliability of preventing the lead screw 30 from rotating relative to the housing 40.

[0113] In one embodiment, the third limiting surface 93 and the first limiting surface 91 are symmetrically arranged with respect to the central plane of the lead screw 30, and the fourth limiting surface 94 and the second limiting surface 92 are symmetrically arranged with respect to the central plane of the lead screw 30. This facilitates the one-time stamping forming of the bushing 80 and reduces costs, and also facilitates installation.

[0114] In one embodiment, the third limiting surface 93 and the first limiting surface 91, and the fourth limiting surface 94 and the second limiting surface 92 are symmetrically arranged with respect to the same central plane. That is, along the radial direction of the lead screw 30, the third limiting surface 93 and the fourth limiting surface 94 are located on the same side of the central axis of the lead screw 30, and the second limiting surface 92 and the first limiting surface 91 are located on the same side of the central axis of the lead screw 30, and the third limiting surface 93 and the first limiting surface 91, and the fourth limiting surface 94 and the second limiting surface 92 are symmetrical with respect to the central plane of the lead screw 30. This facilitates the one-time stamping forming of the bushing 80 and reduces costs, and also facilitates installation.

[0115] In one embodiment, the first limiting surface 91, the second limiting surface 92, the third limiting surface 93, and the fourth limiting surface 94 are all planar and parallel to each other. Along the radial direction of the lead screw 30, the first limiting surface 91 and the third limiting surface 93 are located on the same side of the central plane of the lead screw 30, and the second limiting surface 92 and the fourth limiting surface 94 are also located on the same side of the central plane of the lead screw 30. Furthermore, along the radial direction of the lead screw 30, the first limiting surface 91 and the third limiting surface 93 are located on opposite sides of the central plane of the lead screw 30. Thus, the first limiting surface 91, the third limiting surface 93, and the inner circumferential surface of the bushing 80 together form a racetrack-shaped inner contour, and the second limiting surface 92, the fourth limiting surface 94, and the outer circumferential surface of the bushing 80 together form a racetrack-shaped outer contour. This further improves the reliability of the bushing 80 in restricting the rotation of the lead screw 30 relative to the housing 40 and further improves the machinability of the bushing 80.

[0116] Alternatively, it can be understood that the inner hole of bushing 80 is a racetrack-shaped hole, or an oblong hole. Please refer to [reference needed]. Figure 27 , Figure 27This is a partial structural schematic diagram of a rear wheel steering system 100 provided in one embodiment of this application. The inner wall surface of the bushing 80 includes two first arcuate surfaces 81 and two first planes 82. The two first arcuate surfaces 81 are arranged opposite each other along one radial direction of the lead screw 30, and the two first planes 82 are arranged opposite each other along the other radial direction of the lead screw 30. For ease of explanation, one radial direction of the lead screw 30 is defined as the first radial direction 001, and the other radial direction of the lead screw 30 is defined as the second radial direction 002, with the first radial direction 001 perpendicular to the second radial direction 002. The two first arcuate surfaces 81 are arranged opposite each other along the first radial direction 001 of the lead screw 30, and the two first planes 82 are arranged opposite each other along the second radial direction 002 of the lead screw 30. The two first arcuate surfaces 81 are connected by a first plane 82. The lead screw 30 is sleeved within the bushing 80. Along the first radial direction 001, the bushing 80 provides the lead screw 30 with a linear degree of freedom to allow the lead screw 30 to move axially. Along the second radial direction 002, the bushing 80 abuts against the lead screw 30 via two first planes 82, forming a rigid constraint that restricts the rotation of the lead screw 30 relative to the bushing 80. Similarly, the outer wall surface of the bushing 80 includes two second arcuate surfaces 83 and two second planes 84. The two second arcuate surfaces 83 are arranged opposite each other along the first radial direction 001 of the lead screw 30, and the two second planes 84 are arranged opposite each other along the second radial direction 002 of the lead screw 30. The two second arcuate surfaces 83 are connected by a second plane 84. The bushing 80 is disposed within the positioning hole 4111 of the housing 40. Along the first radial direction 001, the positioning hole 4111 provides the bushing 80 with a linear degree of freedom, allowing the bushing 80 to move axially along the lead screw 30. Along the second radial direction 002, the inner wall of the positioning hole 4111 abuts against the two second planes 84 of the bushing 80, forming a rigid constraint that restricts the rotation of the bushing 80 relative to the housing 40.

[0117] In one embodiment, the length of the bushing 80 along the axial direction of the lead screw 30 is greater than the diameter of the inner circumferential surface of the bushing 80 along the radial direction of the lead screw 30. (See also...) Figure 28 , Figure 28 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application. For ease of explanation, the length of the bushing 80 along the axial direction of the lead screw 30 is defined as l, and the radial diameter of the bushing 80 along the lead screw 30 is defined as d, where l > d. In this embodiment, the axial length of the bushing 80 is larger than the outer circumferential diameter of the lead screw 30, which can improve the guiding effect of the bushing 80 on the lead screw 30 and ensure that the lead screw 30 moves smoothly along the axial direction of the lead screw 30 under the drive of the bushing.

[0118] In one embodiment, along the axial direction of the lead screw 30, the length of the first limiting surface 91 is less than or equal to the length of the bushing 80, and the length of the second limiting surface 92 is less than or equal to the length of the bushing 80. In this embodiment, the bushing 80 is fixed relative to the housing 40, and the lead screw 30 forms an axial displacement within the bushing 80. The fact that the axial length of the first limiting surface 91 or the second limiting surface 92 is less than the axial length of the bushing 80 does not affect the limiting effect of the limiting structure 90. The fact that the axial length of the first limiting surface 91 or the second limiting surface 92 is equal to the axial length of the bushing 80 increases the contact area between the limiting structure 90 and the lead screw 30 and the housing 40, respectively, thereby improving the reliability of the limiting structure 90. By limiting the axial length of the first limiting surface 91 and the second limiting surface 92 to be less than or equal to the length of the bushing 80, it is possible to effectively ensure that the bushing 80 restricts the rotation of the lead screw 30 relative to the housing 40, while also reducing processing and lowering costs.

[0119] In one embodiment, the limiting structure 90 includes a first limiting structure and a second limiting structure, which extend radially along the lead screw 30. The first limiting structure is located on the inner circumferential surface of the bushing 80, and the second limiting structure is located on the outer circumferential surface of the bushing 80. Along the circumferential direction of the lead screw 30, the first limiting structure abuts against the lead screw 30, and the second limiting structure abuts against the housing 40. The first and second limiting structures are used to limit the rotation of the lead screw 30 during axial movement. In this embodiment, the first and second limiting structures extending radially along the lead screw 30 can be respectively engaged with the lead screw 30 and the housing 40 circumferentially, similarly limiting the rotation of the lead screw 30 relative to the housing 40 during axial displacement.

[0120] Please refer to the above. Figure 17 , Figure 17 This is a partial cross-sectional structural diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0121] In one embodiment, the first limiting structure includes a first protrusion 95, and the second limiting structure includes a second protrusion 96. The first protrusion 95 extends radially from the inner circumferential surface of the bushing 80 toward a plane close to the center of the lead screw 30, and the second protrusion 96 extends radially from the outer circumferential surface of the bushing 80 toward a plane away from the center of the lead screw 30. The first protrusion 95 is used to be embedded in the lead screw 30 and abuts against the lead screw 30 circumferentially, and the second protrusion 96 is used to be embedded in the housing 40 and abuts against the housing 40 circumferentially. Exemplarily, the outer circumferential surface of the lead screw 30 includes a first limiting groove 33, which is recessed radially from the outer surface of the lead screw 30 toward the central axis of the lead screw 30. The inner wall of the positioning hole 4111 of the housing 40 includes a second limiting groove (not shown), which is recessed radially from the inner wall of the positioning hole 4111 toward a plane away from the central axis of the lead screw 30. The first protrusion 95 is used to embed into the first limiting groove 33 and abut against the groove wall of the first limiting groove 33, thereby restricting the rotation of the lead screw 30 relative to the bushing 80. The second protrusion 96 is used to embed into the second limiting groove and abut against the groove wall of the second limiting groove, thereby restricting the rotation of the bushing 80 relative to the housing 40.

[0122] This application provides a first protrusion 95 and a second protrusion 96 on the inner and outer circumferential surfaces of the bushing 80, respectively, allowing the bushing 80 to abut against the lead screw 30 and the housing 40 via the first and second limiting structures, thereby restricting the rotation of the lead screw 30 relative to the housing 40. Furthermore, the cooperation between the protrusions and the limiting grooves further improves the reliability of the limiting of the lead screw 30.

[0123] Please refer to the above. Figure 18 , Figure 18 This is a partial cross-sectional structural diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0124] In one embodiment, the first limiting structure includes a first groove 97, and the second limiting structure includes a second groove 98. The first groove 97 is recessed radially from the inner circumferential surface of the bushing 80 toward a plane away from the center of the lead screw 30, and the second protrusion 96 is recessed radially from the outer circumferential surface of the bushing 80 toward a plane close to the center of the lead screw 30. The lead screw 30 is used to be embedded in the first groove 97 and abuts against the bushing 80 circumferentially, and the housing 40 is used to be embedded in the second groove 98 and abuts against the bushing 80 circumferentially. Exemplarily, the outer circumferential surface of the lead screw 30 includes a first limiting protrusion 34, which extends radially from the outer surface of the lead screw 30 toward a central axis away from the lead screw 30. The inner wall of the positioning hole 4111 of the housing 40 includes a second limiting protrusion (not shown), which extends radially from the inner wall of the positioning hole 4111 toward a plane close to the center axis of the lead screw 30. The first limiting protrusion 34 is used to embed into the first groove 97 and abut against the groove wall of the first groove 97, thereby limiting the rotation of the lead screw 30 relative to the bushing 80. The second limiting protrusion is used to embed into the second groove 98 and abut against the groove wall of the second groove 98, thereby limiting the rotation of the bushing 80 relative to the housing 40.

[0125] This application provides a first groove 97 and a second groove 98 on the inner and outer circumferential surfaces of the bushing 80, respectively, allowing the bushing 80 to abut against the lead screw 30 and the housing 40 via the first and second limiting structures, thereby restricting the rotation of the lead screw 30 relative to the housing 40. Furthermore, the combination of the grooves and the limiting protrusions further enhances the reliability of the limiting of the lead screw 30.

[0126] In one embodiment, the first limiting structure and the second limiting structure extend in the same direction along the radial direction of the lead screw 30. This results in a relatively uniform thickness of the circumferential bushing 80 along the lead screw 30, facilitating the machining and forming of the bushing 80 and reducing costs.

[0127] It should be noted that the number, positional arrangement, and form of the first and second limiting structures in the above embodiments are merely illustrative examples. That is, in other embodiments of this application, the number of the first and second limiting structures may include, but is not limited to, one; it can be two, three, or four, etc. The first and second limiting structures can extend in the same direction or in different directions, as long as one is located on the inner circumferential surface of the bushing 80 and the other on the outer circumferential surface of the bushing 80. One of the first and second limiting structures may include a groove, and the other may include a protrusion, which can also achieve the limiting of the lead screw 30. This application does not impose any particular limitations on these aspects.

[0128] In one embodiment, the rear wheel steering gear 100 provided in this application includes two bushings 80, which are respectively sleeved on both ends of the lead screw 30 along the axial direction. That is, the two positioning holes 4111 of the housing 40 are used to fix one bushing 80, and the two bushings 80 are used to jointly support the lead screw 30. Along the axial direction of the lead screw 30, the projections of the limiting structures 90 of the two bushings 80 do not coincide. That is, the orthographic projections of the limiting structures 90 of the two bushings 80 along the axial direction of the lead screw 30 on the same plane are spaced apart. Alternatively, it can be understood that the extending directions of the limiting structures 90 of the two bushings 80 are different. Therefore, the directions of the gaps between the limiting structures 90 of the two bushings 80 and the lead screw 30 are different, and the directions of the gaps between the limiting structures 90 of the two bushings 80 and the housing 40 are also different. That is, the limiting structure 90 of the two bushings 80 has different abutting positions with the lead screw 30 and the housing 40, which helps to improve the force on the lead screw 30 and improve the reliability of the limiting structure 90.

[0129] Please refer to the above. Figure 19 and Figure 20 ,in Figure 19 A cross-sectional view of one side of the rear wheel steering system 100 provided in one embodiment of this application; Figure 20 This is a cross-sectional structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application from another side.

[0130] In one embodiment, a first gap 003 is included between the limiting structure 90 of the bushing 80 and the lead screw 30 along the circumferential direction of the lead screw 30. The first gap 003 is used to ensure that the lead screw 30 does not interfere when sliding within the housing 40. That is, a clearance fit is adopted between the bushing 80 and the lead screw 30. Thus, during the steering process of the rear wheel 100 of this application driving the rear wheel 1002, the first gap 003 can provide linear freedom to the lead screw 30, ensuring that the bushing can smoothly drive the lead screw 30 to move axially relative to the housing 40, avoiding interference from the housing 40 to the axial displacement of the lead screw 30. A second gap 004 is included between the limiting structure 90 and the housing 40, which allows the bushing 80 to be installed within the housing 40. That is, a clearance fit is adopted between the bushing 80 and the lead screw 30, which facilitates the assembly between the bushing 80 and the housing 40 of this application.

[0131] The sum of the first gap 003 and the second gap 004 is used to limit contact between the sensing element 60 and the groove wall of the receiving groove 41. In this embodiment, the lead screw 30 may rotate slightly within the range of the superposition of the first gap 003 and the second gap 004 during axial sliding. By limiting the sum of the first gap 003 and the second gap 004, the rotation angle of the lead screw 30 can be limited, thereby avoiding contact friction between the sensing element 60 and the groove wall of the receiving groove 41, and thus improving the NVH performance of the entire vehicle.

[0132] In one embodiment, the bushing 80 and the lead screw 30 are clearance-fitted.

[0133] In one embodiment, the bushing 80 and the locating hole 4111 of the housing 40 are interference-fitted.

[0134] In one embodiment, the positioning hole 4111 of the housing 40 is provided with a radial protrusion 47. Please refer to [reference needed]. Figure 29 , Figure 29 This is a partially enlarged schematic diagram of a rear wheel steering system 100 provided in one embodiment of this application. A radial protrusion 47 is located on the side of the bushing 80 near the sensor 60 along the axial direction of the lead screw 30. The radial protrusion 47 extends from the inner wall of the positioning hole 4111 toward the surface of the lead screw 30 along the radial direction of the lead screw 30. The radial protrusion 47 abuts against the end face of the bushing 80 along the axial direction of the lead screw 30. The radial protrusion 47 restricts the displacement of the bushing 80 relative to the housing 40 along the axial direction of the lead screw 30, ensuring that the bushing 80 is reliably installed within the positioning hole 4111 of the housing 40.

[0135] Please refer to the above. Figure 21 , Figure 21 This is a cross-sectional structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0136] In one embodiment, along the arrangement direction of the displacement sensor 50 and the sensing element 60, the screw 70 includes a section extending into the lead screw 30. Along the radial direction of the lead screw 30, the section of the screw 70 extending into the lead screw 30 does not protrude beyond the surface of the lead screw 30. For ease of description, this application defines the section of the screw 70 extending into the lead screw 30 as the first section 71. Along the radial direction of the lead screw 30, the first section 71 extends into the lead screw 30, and the first section 71 does not protrude beyond the outer surface of the lead screw 30. That is, along the arrangement direction of the displacement sensor 50 and the sensing element 60, the length of the first section 71 is less than or equal to the outer diameter of the lead screw 30. Thus, the first section 71 of the screw 70 is completely accommodated within the lead screw 30, preventing the first section 71 of the screw 70 from contacting the bottom or wall of the receiving groove 41 and causing friction, thereby improving the overall NVH performance of the vehicle.

[0137] Please refer to the above. Figure 22 , Figure 22 This is a cross-sectional structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0138] In one embodiment, along the radial direction of the lead screw 30, a portion of the screw 70 extends into the surface of the lead screw 30 beyond its outer edge. The sum of a first gap 003 and a second gap 004 restricts contact between the portion of the screw 70 extending into the lead screw 30 beyond its outer edge and the wall of the receiving groove 41. Specifically, along the arrangement direction of the displacement sensor 50 and the sensing element 60, the length of the first portion 71 is greater than the outer diameter of the lead screw 30. Along the radial direction of the lead screw 30, the first portion 71 protrudes from the outer surface of the lead screw 30 in a direction away from the sensing element 60. The sum of the first gap 003 and the second gap 004 restricts contact between the portion of the first portion 71 protruding from the outer surface of the lead screw 30 and the wall of the receiving groove 41. More specifically, the sum of the first gap 003 and the second gap 004 restricts contact between the portion of the first portion 71 protruding from the outer surface of the lead screw 30 and the radial wall 412 of the receiving groove 41.

[0139] In this embodiment, the first segment 71 of the screw 70 extends out of the lead screw 30, resulting in a longer mating dimension between the screw 70 and the lead screw 30 to improve reliability. By limiting the sum of the first gap 003 and the second gap 004, the rotation angle of the screw 70 with the lead screw 30 can be limited, preventing the first segment 71 of the screw 70 from contacting and rubbing against the radial groove wall 412 of the receiving groove 41 after extending out of the lead screw 30, thereby improving the overall NVH performance of the vehicle.

[0140] Please cooperate. Figure 23 and Figure 24 ,in Figure 23 This is a partially exploded structural diagram of the rear wheel steering system 100 provided in one embodiment of this application; Figure 24 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0141] In one embodiment, the sensing element 60 includes a plastic part 61 and a sensing plate 62. The plastic part 61 supports the sensing plate 62, and another section of the screw 70 is used to fix the plastic part 61. For ease of description, this application defines the other section of the screw 70 as the second section 72. Exemplarily, the second section 72 is used to connect with the first section 71, and the second section 72 passes through the plastic part 61 and engages with the first section 71 to fix the plastic part 61 to the lead screw 30. Along the radial direction of the lead screw 30, the sensing plate 62 is located at the end of the plastic part 61 away from the lead screw 30 and is supported by the plastic part 61. During the axial displacement of the lead screw 30, the plastic part 61 and the sensing plate 62 are axially displaced with the lead screw 30. The displacement sensor 50 is fixed to the cover plate 42 and is used to detect the axial displacement of the lead screw 30 relative to the housing 40 through the sensing plate 62.

[0142] In this embodiment, a plastic part 61 is used to support the sensing plate 62. The plastic part 61 can reduce the weight of the sensing element 60 while ensuring that the sensing plate 62 slides synchronously with the lead screw 30 to improve the detection accuracy of the displacement sensor 50.

[0143] In one embodiment, along the circumference of the lead screw 30, the plastic part 61 includes two opposing sidewalls 63. The arrangement direction of the two sidewalls 63 is the same as the arrangement direction of the two radial groove walls 412. Each sidewall 63 is used to fix a film layer 64, the material of which includes at least one of nitrile rubber, polysulfide rubber, or butyl rubber. Due to the low coefficient of friction of the above materials, if an excessive rotation angle occurs unexpectedly during the axial displacement of the lead screw 30, the film layer 64 can abut against the groove wall of the plastic part 61 and reduce the noise generated by friction, thereby improving the overall NVH performance of the vehicle.

[0144] In one embodiment, the sidewall 63 includes a plurality of grooves 65, with each groove 65 recessed towards the other sidewall 63 along the arrangement direction of the two sidewalls 63. That is, the opening of the groove 65 on each sidewall 63 faces the radial groove wall 412 on the same side. The plurality of grooves 65 are used to accommodate grease. Thus, if an excessive rotation angle occurs unexpectedly during the axial displacement of the lead screw 30, the grease in the grooves 65 can reduce the noise generated by friction, thereby improving the overall NVH performance of the vehicle.

[0145] In one embodiment, the opening of the groove 65 is circular, and the grooves 65 are arranged at intervals.

[0146] Please refer to the above. Figure 25 , Figure 25 This is a partial structural schematic diagram of the rear wheel steering system 100 provided in one embodiment of this application. In one embodiment, the groove 65 has a rhomboid opening, and the grooves 65 are connected sequentially.

[0147] In one embodiment, the grooves 65 are arranged at intervals or connected sequentially along the axial direction of the lead screw 30.

[0148] Please refer to the above. Figure 26 , Figure 26 This is a partial cross-sectional structural diagram of the rear wheel steering system 100 provided in one embodiment of this application.

[0149] In one embodiment, the inner wall of the positioning hole 4111 of the housing 40 includes a vent groove 48, which extends axially along the lead screw 30. Radially along the lead screw 30, the vent groove 48 is recessed from the surface of the inner wall of the positioning hole 4111 in a direction away from the lead screw 30. The vent groove 48 helps balance the air pressure within the positioning hole 4111, facilitating the insertion of the bushing 80 into the positioning hole 4111.

[0150] In one embodiment, the vehicle 1000 provided in this application further includes a front wheel steering unit 500. The housing 40 of the front wheel steering unit 500 is used to accommodate another lead screw 30, which receives drive and generates displacement along its axial direction. The other lead screw 30 is used to deflect the front wheel 1003. Another bushing 80 is included between the other lead screw 30 and the housing 40 of the front wheel steering unit 500. A limiting structure 90 of the other bushing 80 is used to restrict rotation when the other lead screw 30 moves axially.

[0151] That is, the rear wheel steering unit 100 provided in this application can be configured to correspond to the front wheel 1003 as a front wheel steering unit 500, and can be used to control the deflection angle of the front wheel 1003 relative to the frame 1001. In the embodiment of this application, the limiting structure 90 of the bushing 80 of the front wheel steering unit 500 is used to limit the rotation of the lead screw 30 of the front wheel steering unit 500 relative to the housing 40 of the front wheel steering unit 500, which can further improve the NVH performance of the front wheel steering unit 500 of the vehicle 1000.

[0152] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A rear-wheel steering system, characterized in that, The rear wheel steering system includes a drive unit, a nut, a lead screw, a displacement sensor, a sensing element, and a bushing, wherein: The housing of the rear wheel steering gear is used to accommodate the nut and the lead screw, the lead screw is assembled in the nut, the drive device is used to drive the nut to rotate, the nut drives the lead screw to produce displacement along the lead screw axis, and the lead screw is used to drive the vehicle wheels to deflect. The housing of the rear wheel steering gear is used to house the sensor, which is fixed to the lead screw by a screw. The displacement sensor is fixed above the sensor along the radial direction of the lead screw, and the displacement sensor is used to detect the displacement of the lead screw through the sensor. Along the radial direction of the lead screw, a bushing is included between the lead screw and the housing. The bushing includes a limiting structure for limiting the rotation of the lead screw when it moves along the axial direction of the lead screw, and for limiting the rotation of the sensing element caused by the lead screw.

2. The rear wheel steering system according to claim 1, characterized in that, The limiting structure includes a first limiting surface and a second limiting surface, both of which are planes. The first limiting surface is located on the inner circumferential surface of the bushing, and the second limiting surface is located on the outer circumferential surface of the bushing. Along the circumferential direction of the lead screw, the first limiting surface abuts against the lead screw, and the second limiting surface abuts against the housing. The first limiting surface and the second limiting surface are used to limit the rotation of the lead screw when it moves along the axial direction of the lead screw.

3. The rear wheel steering system according to claim 2, characterized in that, The first limiting surface and the second limiting surface are parallel to each other along the radial direction of the lead screw. The first limiting surface and the second limiting surface are located on the same side of the center plane of the lead screw. The distance between the first limiting surface and the center plane of the lead screw is less than the inner circumferential radius of the bushing, and the distance between the second limiting surface and the center plane of the lead screw is less than the outer circumferential radius of the bushing.

4. The rear wheel steering system according to claim 2, characterized in that, The limiting structure includes a third limiting surface and a fourth limiting surface. The third limiting surface and the first limiting surface are symmetrically arranged with respect to the central plane of the lead screw, and the fourth limiting surface and the second limiting surface are symmetrically arranged with respect to the central plane of the lead screw.

5. The rear wheel steering system according to claim 2, characterized in that, The lengths of the first limiting surface and the second limiting surface along the axial direction of the lead screw are respectively less than or equal to the length of the bushing.

6. The rear wheel steering system according to claim 1, characterized in that, The limiting structure includes a first limiting structure and a second limiting structure, which extend radially along the lead screw. The first limiting structure is located on the inner circumferential surface of the bushing, and the second limiting structure is located on the outer circumferential surface of the bushing. Along the circumferential direction of the lead screw, the first limiting structure abuts against the lead screw and the second limiting structure abuts against the housing. The first limiting structure and the second limiting structure are used to restrict the lead screw from rotating when it moves axially along the lead screw.

7. The rear wheel steering system according to any one of claims 1-6, characterized in that, The length of the bushing along the axial direction of the lead screw is greater than the diameter of the inner circumferential surface of the bushing along the radial direction of the lead screw.

8. The rear wheel steering system according to any one of claims 1-6, characterized in that, The rear wheel steering gear includes two bushings, which are respectively sleeved on both ends of the lead screw along the axial direction of the lead screw, and the projections of the limiting structures of the two bushings along the axial direction of the lead screw do not coincide.

9. The rear wheel steering system according to any one of claims 1-6, characterized in that, The housing includes a receiving groove for accommodating a portion of the lead screw, the displacement sensor, the screw, and the sensing element, wherein: Along the circumference of the lead screw, there is a first gap between the limiting structure and the lead screw, and a second gap between the limiting structure and the housing. The sum of the first gap and the second gap is used to limit the contact between the sensing element and the wall of the receiving groove.

10. The rear wheel steering system according to claim 9, characterized in that, Along the alignment direction of the displacement sensor and the sensing element, the screw includes a section extending into the lead screw, wherein: The portion of the screw extending radially into the lead screw does not protrude beyond the surface of the lead screw; or, The screw extends radially into the section of the lead screw beyond the surface of the lead screw, and the sum of the first gap and the second gap is used to limit the portion of the screw extending into the lead screw beyond the surface of the lead screw from contacting the groove wall of the receiving groove.

11. The rear wheel steering system according to claim 10, characterized in that, The sensing element includes a plastic part, the other end of the screw is used to fix the plastic part, the plastic part is used to support the sensing plate of the sensing element, and the displacement sensor is used to detect the axial displacement of the lead screw through the sensing plate.

12. The rear wheel steering system according to claim 11, characterized in that, The plastic part along the circumference of the lead screw includes two opposite sidewalls, each sidewall for fixing a film layer, the film layer being made of at least one of nitrile rubber, polysulfide rubber, or butyl rubber.

13. The rear wheel steering system according to claim 12, characterized in that, The sidewall includes a plurality of grooves for receiving grease, wherein: The groove opening is circular, and the grooves are arranged at intervals; or, The groove opening is rhomboid, and all the grooves are connected in sequence.

14. A vehicle, characterized in that, The vehicles include: Two rear wheels, each located on one side of the vehicle; Two rear wheel steering systems as described in any one of claims 1-13, each of the rear wheel steering systems being used to drive the deflection of the rear wheels on one side of the vehicle.

15. The vehicle according to claim 14, characterized in that, The vehicle includes front wheels and a front wheel steering unit. The housing of the front wheel steering unit is used to accommodate another lead screw, which is used to receive drive and generate displacement along the axial direction of the other lead screw. The other lead screw is used to drive the front wheels to deflect. Another bushing is included between the other lead screw and the housing of the front wheel steering unit. The limiting structure of the other bushing is used to limit the rotation generated when the other lead screw moves axially.

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