Rear wheel steering gear and vehicle

Abstract

The invention provides a rear wheel steering gear and a vehicle. The rear wheel steering gear comprises a steering motor, a transmission mechanism and a lead screw, the steering motor is used for driving the lead screw to drive rear wheels of the vehicle to steer after changing the rotating speed through the transmission mechanism, and the distance between the central axis of a motor shaft of the steering motor and the central axis of a screw rod of the lead screw is smaller than the shell radius of the steering motor in the radial direction of the screw rod of the lead screw. According to the rear wheel steering gear, by limiting the radial distance between the steering motor and the lead screw, the size of the rear wheel steering gear is reduced so as to increase the internal space of a vehicle.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle steering, and in particular to a rear wheel steering device and a vehicle. Background Art

[0002] The rear wheel steering gear is used to control the rear wheel steering of the vehicle to reduce the turning radius of the vehicle and improve the stability and comfort of the vehicle. If the rear wheel steering gear is too large, it will occupy the interior space of the vehicle, so it is necessary to reduce the size of the rear wheel steering gear to save the interior space of the vehicle. Summary of the invention

[0003] The present application provides a rear wheel steering gear and a vehicle. The rear wheel steering gear reduces the volume of the rear wheel steering gear to increase the interior space of the vehicle by limiting the radial spacing between the steering motor and the lead screw.

[0004] In the first aspect, the present application provides a rear-wheel steering gear, which includes a steering motor, a transmission mechanism and a screw. The steering motor is used to drive the screw to steer the rear wheels of the vehicle after changing the rotation speed through the transmission mechanism. The distance between the central axis of the motor shaft of the steering motor and the central axis of the screw of the screw along the radial direction of the screw is smaller than the shell radius of the steering motor.

[0005] The steering motor of the rear wheel steering device provided by the present application drives the screw of the lead screw to rotate through a transmission mechanism, thereby driving the rear wheels of the vehicle to steer. The transmission mechanism is used to reduce the rotation speed output by the steering motor to increase the torque, thereby ensuring that the lead screw reliably drives the rear wheels to steer. The radial dimension of the steering motor along the screw is relatively large. The rear wheel steering device of the present application utilizes the cooperation of the transmission mechanism and the lead screw so that the screw of the lead screw at least partially overlaps with the housing of the steering motor along the radial direction, thereby compressing the radial dimension of the rear wheel steering device along the screw, thereby reducing the volume of the rear wheel steering device and increasing the internal space of the vehicle.

[0006] In one implementation, the transmission mechanism includes a planetary gear transmission mechanism, the sun gear of the planetary gear transmission mechanism is used to receive the driving rotation of the steering motor, the planetary gears of the planetary gear transmission mechanism are used to mesh with the sun gear and output the driving rotation through the planetary gear support of the planetary gear transmission mechanism, and the outer ring gear of the planetary gear transmission mechanism is used to be fixed to the housing of the rear wheel steering gear and mesh with the planetary gears.

[0007] In this implementation, the sun gear and planetary gear bracket of the planetary gear transmission mechanism rotate around the same central axis. Under the premise of ensuring the reduction ratio of the transmission mechanism, the radial distance between the central axis of the motor shaft of the steering motor and the central axis of the screw can be reduced, thereby compressing the overall size of the rear wheel steering gear of this application along the radial direction of the screw.

[0008] In one implementation, along the axial direction of the screw, the central axis of the motor shaft of the steering motor, the central axis of the sun gear, and the central axis of the screw of the lead screw coincide in sequence.

[0009] In this implementation, the steering motor, planetary gear transmission mechanism and screw of the rear wheel steering gear are arranged coaxially, the central axis of the screw coincides with the central axis of the steering motor, and the size of the rear wheel steering gear along the radial direction of the screw is roughly equal to the shell size of the steering motor, which can better limit the overall size of the rear wheel steering gear.

[0010] In one implementation, along the axial direction of the screw, the center axis of the sun wheel coincides with the center axis of the screw of the lead screw; along the radial direction of the screw, the distance between the center axis of the sun wheel and the center axis of the motor shaft of the steering motor is greater than the radius of the motor shaft.

[0011] In this implementation, the planetary gear transmission mechanism is arranged coaxially with the lead screw. Along the radial direction of the screw, the distance between the center axis of the screw and the center axis of the steering motor is relatively small. The size of the rear wheel steering gear is roughly equal to the housing size of the steering motor, which can also better limit the overall size of the rear wheel steering gear.

[0012] In one implementation, the transmission mechanism includes a parallel axis gear transmission mechanism, the input wheel of the parallel axis gear transmission mechanism is used to receive the driving rotation of the steering motor, the output wheel of the parallel axis gear transmission mechanism is used to mesh with the input wheel and drive the sun wheel to rotate by being coaxially fixed with the sun wheel, and the diameter of the input wheel is smaller than the diameter of the output wheel.

[0013] In this implementation, the transmission mechanism increases the reduction ratio through the parallel axis gear transmission mechanism, which can reduce the volume of the planetary gear transmission mechanism, thereby controlling the overall volume of the transmission mechanism, so that the radial dimension of the transmission mechanism along the screw is smaller than the dimension of the steering motor housing, and taking into account the spacing between the central axis of the lead screw and the central axis of the motor shaft, the overall radial dimension of the rear wheel steering gear along the screw is controlled under the premise of satisfying the torque output by the rear wheel steering gear. The parallel axis gear transmission mechanism also has a high transmission efficiency, which can improve the overall transmission efficiency of the rear wheel steering gear.

[0014] In one implementation, the transmission mechanism includes a transmission wheel and a belt, and the motor shaft drives the transmission wheel to rotate and drives the belt to drive the sun wheel through the transmission wheel. The structure of the transmission wheel and the belt is relatively simple, which is conducive to the internal structure arrangement of the rear wheel steering gear.

[0015] In one implementation method, the planetary wheel bracket is fixedly connected to the screw of the lead screw, the nut of the lead screw is engaged with the periphery of the screw, the nut along the axial direction of the screw is used to fix the steering rod connected to the rear wheel steering gear, and the lead screw is used to receive the driving rotation of the planetary gear transmission mechanism and to drive the rear wheels of the vehicle to steer through the steering rod.

[0016] In this implementation, the nut and the screw of the lead screw are fixedly connected to the vehicle's steering tie rod and the transmission mechanism of the rear wheel steering gear respectively. The steering motor of the rear wheel steering gear drives the screw to rotate through the transmission mechanism, so as to drive the nut to drive the steering tie rod to move along the central axis of the screw, so that the rear wheel steering gear can drive the rear wheels of the vehicle to steer through the steering tie rod.

[0017] In one implementation method, the planetary wheel bracket is fixedly connected to the nut of the lead screw, the nut of the lead screw is engaged with the periphery of the screw, the screw is used to fix the steering rod connected to the rear wheel steering gear along the axial direction of the screw, and the lead screw is used to receive the driving rotation of the planetary gear transmission mechanism and to drive the rear wheels of the vehicle to steer through the steering rod.

[0018] In this implementation, the nut and the screw of the lead screw are fixedly connected to the transmission mechanism of the rear wheel steering gear and the steering tie rod of the vehicle respectively. The steering motor of the rear wheel steering gear drives the nut to rotate through the transmission mechanism to drive the screw to drive the steering tie rod to move axially, so that the rear wheel steering gear can drive the rear wheels of the vehicle to steer through the steering tie rod.

[0019] In one implementation, the steering tie rod includes two opposite ends along the axial direction of the screw rod, one of the two ends is used to be embedded in the housing of the transmission mechanism and used to transmit the connecting screw, and the other end is used to drive a rear wheel of the vehicle.

[0020] In one implementation, the steering tie rod includes a receiving groove, the notch of which faces the sun gear along the axial direction of the screw, and the receiving groove is used to receive a section of the screw.

[0021] In one implementation, the nut is fixed to the groove wall of the accommodating groove, and the nut is used to receive the drive of the screw rod and to move along the axial direction of the screw rod to drive the steering rod.

[0022] In one implementation, a nut is fixed to a motor shaft, and the nut is used to rotate with the motor shaft to drive the screw rod to move axially and drive the steering rod.

[0023] In one implementation, the planetary gear transmission mechanism includes three planetary gears, and may also be configured to include four or five planetary gears as required.

[0024] In this implementation, when the planetary gear transmission mechanism includes three planetary wheels, the transmission mechanism can balance the reduction ratio, torque carrying capacity, NVH noise, and installation convenience, and improve the overall performance of the rear wheel steering gear. When the planetary gear transmission mechanism includes five planetary wheels, the torque carrying capacity of the transmission mechanism is large, which can improve the reliability of the rear wheel steering gear. When the planetary gear transmission mechanism includes four planetary wheels, the rear wheel steering gear can take into account the reduction ratio, torque carrying capacity, NVH noise, and installation convenience.

[0025] In one implementation, the lead screw is a planetary roller lead screw, which includes a plurality of planetary rollers. The plurality of planetary rollers surround the screw at intervals along the circumference of the screw and are respectively engaged with the screw. The lead screw nut is transmission-connected to the screw via the plurality of planetary rollers.

[0026] In this implementation, the planetary roller screw has high transmission efficiency and good self-locking ability. It can drive the screw to rotate and ensure transmission efficiency when driven by the steering motor, and can limit the rotation of the screw when the steering motor stops driving, thereby preventing the rear wheels of the vehicle from turning unexpectedly after being impacted.

[0027] In one implementation, the planetary roller screw includes 10 planetary rollers.

[0028] In this implementation, when the planetary roller screw includes 10 planetary rollers, the locking ability and installation convenience of the screw can be balanced, avoiding unexpected steering of the rear wheels due to a small number of planetary rollers, and avoiding inconvenient installation of the planetary roller screw due to a large number of planetary rollers.

[0029] In one implementation, the nut is fixed to the groove wall of the accommodating groove, the screw is used to rotate with the transmission mechanism and drive multiple planetary rollers to move axially along the screw, and the multiple planetary rollers are used to drive the nut to move synchronously.

[0030] In one implementation, a nut is fixed to a transmission mechanism, and the nut is used to rotate with the transmission mechanism to drive a plurality of planetary rollers to rotate around a screw rod, and the plurality of planetary rollers are used to drive the screw rod to move along its own axial direction.

[0031] In one implementation, the outer peripheral surface of the screw includes radial protrusions, which are arranged at intervals along the axial direction of the screw on the side of the nut away from the sun gear, and the diameter of the radial protrusions is larger than the inner diameter of the nut; or, the radial protrusions are used to be embedded in the groove wall of the accommodating groove.

[0032] In one implementation, in response to a first control signal, the steering motor is used to continuously output a first preset torque toward the planetary roller screw, and the first control signal is used to instruct the rear wheel steering gear to drive the rear wheels of the vehicle to turn to a preset angle.

[0033] In this implementation, after the rear-wheel steering gear provided in the present application drives the rear wheels of the vehicle to turn to a preset angle, the steering motor is also used to continuously output a first preset torque to fix the planetary roller screw through a transmission mechanism, thereby increasing the support torque for the rear wheels to limit the rear wheels from producing unwanted steering.

[0034] In one implementation, the first preset torque is equal to the stall torque of the steering motor, or the difference between the first preset torque and the stall torque of the steering motor is less than the first preset difference.

[0035] In one implementation, the screw is a ball screw, and the rear wheel steering gear includes a locking mechanism, which is used to transmit and connect the motor shaft and the ball screw. The locking mechanism is used to receive the drive of the motor shaft to drive the ball screw to move when the steering motor is working, and the locking mechanism is also used to limit the movement of the ball screw when the steering motor stops working.

[0036] In this implementation, the ball screw has a high transmission efficiency, and can drive the screw to rotate when driven by the steering motor and improve the overall transmission efficiency of the rear wheel steering gear. The locking mechanism is used to achieve self-locking of the rear wheel steering gear to prevent the rear wheels of the vehicle from unexpectedly turning after being impacted.

[0037] In one implementation, the locking mechanism includes a driving member, a one-way clutch and a driven member, wherein the driving member is used to be fixedly connected to the motor shaft, the driven member is used to be connected to the ball screw transmission, and the one-way clutch is used to limit the movement of the driven member and to receive the drive of the driving member and drive the driven member.

[0038] In this implementation, the locking mechanism fixedly connects the motor shaft and the ball screw through the driving member and the driven member respectively, and realizes the self-locking function of the rear wheel steering gear by the driving member driving the rotation of the driven member through the one-way clutch and limiting the rotation of the driven member relative to the driving member through the one-way clutch.

[0039] In one implementation, in response to a second control signal, the steering motor is used to continuously output a second preset torque toward the ball screw, and the second control signal is used to instruct the rear wheel steering gear to drive the rear wheels of the vehicle to turn to a preset angle.

[0040] In this implementation, after the rear-wheel steering gear provided in the present application drives the rear wheels of the vehicle to turn to a preset angle, the steering motor is also used to continuously output a second preset torque to fix the transmission mechanism and the ball screw through a locking mechanism, thereby increasing the support torque for the rear wheels to limit the rear wheels from producing unwanted steering.

[0041] In one implementation, the second preset torque is less than the first preset torque. Because the locking ability of the locking mechanism is stronger than that of the planetary roller screw, the steering motor can reduce the output torque to limit the undesired steering of the rear wheels and save energy consumption of the rear wheel steering gear.

[0042] In one implementation, the rear wheel steering gear includes a displacement sensor, and the displacement sensor is used to detect the displacement of the lead screw.

[0043] In this implementation, the rear wheel steering gear detects the displacement of the lead screw to indirectly detect the steering angle of the rear wheel, thereby ensuring reliable steering of the rear wheel.

[0044] In one implementation, the detection component included in the displacement sensor is fixed to the housing of the rear wheel steering gear, and the moving component of the displacement sensor is fixed to the steering rod of the rear wheel and moves along the axial direction of the steering rod.

[0045] In one implementation, the rear wheel steering gear includes two steering motors, two transmission mechanisms and two lead screws, and each steering motor is used to drive a lead screw through a transmission mechanism to drive the rear wheel on one side of the vehicle.

[0046] In one implementation, the rear wheel steering gear includes two transmission mechanisms and two lead screws, the steering motor includes two motor shafts, the two motor shafts are arranged on both sides of the motor stator of the steering motor, and each motor shaft is used to drive a lead screw through a transmission mechanism to drive the rear wheel on one side of the vehicle.

[0047] In one implementation, the rear wheel steering gear includes two transmission mechanisms and two lead screws, and the motor shaft of the steering motor is used to pass through the inner hole of the motor rotor and to drive the two transmission mechanisms respectively.

[0048] In one implementation, the rear wheel steering gear includes two locking mechanisms.

[0049] In one implementation, the screw threads of the two lead screws have the same rotation direction, and the two rear wheels have the same direction of rotation.

[0050] In one implementation, the screw threads of the two lead screws rotate in opposite directions, and the two rear wheels rotate in opposite directions.

[0051] In a second aspect, the present application provides a vehicle, the vehicle comprising one or more rear wheels, and a rear wheel steering device provided by any of the above implementations, the rear wheel steering device being used to drive the one or more rear wheels to steer. The vehicle of the present application has a larger internal space based on the rear wheel steering function, which is conducive to the arrangement of other components of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the implementation manner will be briefly introduced below. Obviously, the drawings described below are only some implementation manners of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 A schematic diagram of the structure of a vehicle provided in one embodiment of the present application;

[0054] Figure 2 A schematic diagram of a partial structure of a vehicle provided in one embodiment of the present application;

[0055] Figure 3 This is a schematic structural diagram of a rear wheel steering device provided in one embodiment of the present application;

[0056] Figure 4 This is a schematic diagram of the exploded structure of a rear wheel steering gear provided in one embodiment of the present application;

[0057] Figure 5 A schematic cross-sectional structure diagram of a rear wheel steering gear provided in one embodiment of the present application;

[0058] Figure 6 A schematic diagram of a partial structure of a rear wheel steering device provided in one embodiment of the present application;

[0059] Figure 7 A schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application;

[0060] Figure 8 A schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application;

[0061] Fig. 9 A partial cross-sectional structural schematic diagram of a rear wheel steering device provided in an embodiment of the present application;

[0062] Fig.10 A schematic diagram of the transmission structure of a rear wheel steering gear provided in one embodiment of the present application;

[0063] Fig.11 A schematic diagram of the transmission structure of a rear wheel steering gear provided in one embodiment of the present application;

[0064] Fig.12 A schematic diagram of a partial structure of a rear wheel steering device provided in one embodiment of the present application;

[0065] Fig.13 A schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application;

[0066] Fig.14 A partial cross-sectional structural schematic diagram of a rear wheel steering device provided in an embodiment of the present application;

[0067] Fig.15 A schematic diagram of a partial structure of a rear wheel steering device provided in one embodiment of the present application;

[0068] Fig.16 A schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application;

[0069] Fig.17 A schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application;

[0070] Fig.18A partial cross-sectional structural schematic diagram of a rear wheel steering device provided in an embodiment of the present application;

[0071] Fig.19 A schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application;

[0072] Fig. 20 A schematic cross-sectional structure diagram of a rear wheel steering gear provided in one embodiment of the present application;

[0073] Fig.21 A schematic diagram of a partial structure of a rear wheel steering device provided in one embodiment of the present application;

[0074] Fig. 22 A partial cross-sectional structural schematic diagram of a rear wheel steering device provided in an embodiment of the present application;

[0075] Fig.23 A partial cross-sectional structural schematic diagram of a rear wheel steering device provided in an embodiment of the present application;

[0076] Fig.24 A schematic diagram of the structure of a vehicle provided in one embodiment of the present application.

[0077] Figure numbers: 1000-vehicle; 1001-frame; 1002-rear wheel; 1003-front wheel; 100-rear wheel steering gear; 10-steering motor; 11-motor shaft; 12-motor stator; 13-motor rotor; 20-transmission mechanism; 21-planetary gear transmission mechanism; 211-sun gear; 212-planetary gear; 213-planetary gear bracket; 2131-shaft hole; 2132-receiving groove; 214-external gear ring; 22-parallel axis gear transmission mechanism; 221-input wheel; 222-output wheel; 30-screw; 30a-planetary roller screw Lever; 30b-ball screw; 31-screw; 311-radial protrusion; 32-nut; 33-planetary roller; 331-first threaded segment; 332-second threaded segment; 34-ball; 40-housing; 41-first housing; 42-second housing; 43-first receiving groove; 50-steering rod; 51-first end; 52-second end; 53-second receiving groove; 60-sensor; 61-displacement sensor; 611-detection component; 612-moving component; 70-locking mechanism; 71-driving member; 72-one-way clutch; 73-driven member. DETAILED DESCRIPTION

[0078] The following will describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of this application.

[0079] The present application provides a rear wheel steering device, which includes a steering motor, a transmission mechanism and a lead screw. The steering motor is used to drive the lead screw to drive the rear wheel steering of the vehicle after the rotation speed is changed by the transmission mechanism. The distance between the motor shaft center axis of the steering motor and the screw center axis of the lead screw along the radial direction of the screw of the lead screw is smaller than the housing radius of the steering motor. The rear wheel steering device of the present application compresses the spatial dimension of the rear wheel steering device along the radial direction of the screw, thereby reducing the volume of the rear wheel steering device and increasing the internal space of the vehicle.

[0080] The present application provides a vehicle, the vehicle includes one or more rear wheels, and a rear wheel steering device provided by the present application, the rear wheel steering device is used to drive the one or more rear wheels to steer. The vehicle of the present application has a larger internal space on the basis of having a rear wheel steering function, which is conducive to the arrangement of other components of the vehicle.

[0081] See also Figure 1 , Figure 1 Schematic diagram of the architecture of a vehicle 1000 provided in one embodiment of the present application.

[0082] like Figure 1 As shown, the vehicle 1000 provided by the present application includes a rear wheel steering gear 100, which is used to be fixed to a vehicle frame 1001 and is drivingly connected to one or more rear wheels 1002 of the vehicle 1000. The rear wheel steering gear 100 is used to drive the one or more rear wheels 1002 of the vehicle 1000 to steer, thereby increasing the steering angle control range of the vehicle 1000 and reducing the phenomenon of understeering or oversteering of the vehicle 1000.

[0083] For example, in some scenarios, when the vehicle 1000 needs to turn or make a U-turn with a smaller turning radius, the front wheels 1003 and the rear wheels 1002 of the vehicle 1000 can be controlled to rotate in opposite directions, thereby reducing the turning radius and improving the flexibility of the vehicle 1000. In other scenarios, when the vehicle 1000 needs to turn at a certain speed, the front wheels 1003 and the rear wheels 1002 of the vehicle 1000 can be controlled to rotate in the same direction, thereby reducing the center of mass side slip angle of the vehicle 1000, reducing the steady-state overshoot of the yaw rate of the vehicle 1000, and thus enhancing the handling stability of the vehicle 1000.

[0084] In one embodiment, the number of the front wheels 1003 and the rear wheels 1002 of the vehicle 1000 provided by the present application are two respectively, the two front wheels 1003 are arranged on both sides of the vehicle 1000, and the two rear wheels 1002 are arranged on both sides of the vehicle 1000. The rear wheel steering device 100 of the present application is used for transmission connection with the two rear wheels 1002 of the vehicle 1000, and is used to drive the two rear wheels 1002 of the vehicle 1000 to change the direction. It should be noted that the number of the front wheels 1003 and the rear wheels 1002 of the vehicle 1000 provided by the present application includes but is not limited to two. For example, in another embodiment, the vehicle 1000 provided by the present application may have multiple front wheels 1003 and multiple rear wheels 1002, and the rear wheel steering device 100 is transmission connected with some of the multiple rear wheels 1002, and is used to drive some of the rear wheels 1002 to change the direction.

[0085] Please see Figures 2 to 5 ,in Figure 2 A schematic diagram of a partial structure of a vehicle 1000 provided in one embodiment of the present application; Figure 3 This is a schematic structural diagram of a rear wheel steering device 100 provided in one embodiment of the present application; Figure 4 This is a schematic diagram of the exploded structure of a rear wheel steering device 100 provided in one embodiment of the present application; Figure 5 It is a schematic cross-sectional structure diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0086] like Figures 2 to 5 As shown, the rear wheel steering device 100 provided by the present application includes a steering motor 10, a transmission mechanism 20 and a lead screw 30. The steering motor 10 is used to drive the lead screw 30 to drive one or more rear wheels 1002 of the vehicle 1000 to steer after the rotation speed is changed by the transmission mechanism 20. That is, the steering motor 10 is used to provide a driving force to change the steering direction of one or more rear wheels 1002. The transmission mechanism 20 is used to drive and connect the motor shaft 11 of the steering motor 10 and the lead screw 30. The transmission mechanism 20 is also used to adjust the speed and torque of the driving force output by the steering motor 10, and transmit the adjusted driving force to the lead screw 30. The lead screw 30 is used to convert the rotational motion of the motor shaft 11 of the steering motor 10 into a linear displacement along the axial direction of the lead screw 30 and output it to one or more rear wheels 1002, so as to drive one or more rear wheels 1002 to deflect relative to the frame 1001, thereby realizing the steering of the rear wheels 1002.

[0087] In one embodiment, the rear wheel steering gear 100 provided in the present application includes a housing 40, which is used to be fixed to the frame 1001. The housing 40 is also used to accommodate the steering motor 10, the transmission mechanism 20, and at least partially accommodate the lead screw 30.

[0088] In one embodiment, the housing 40 includes a first housing 41, and the first housing 41 is fixed relative to the vehicle frame 1001. The steering motor 10 also includes a motor stator 12 and a motor rotor 13. The motor stator 12 and the motor rotor 13 are both accommodated in the first housing 41, and the motor shaft 11 partially extends out of the first housing 41. That is, the first housing 41 is the housing of the steering motor 10. The motor rotor 13 is used to be coaxially fixed to the motor shaft 11. Along the circumference of the motor shaft 11, the motor stator 12 is used to be sleeved on the periphery of the motor rotor 13, and the motor stator 12 is energized to drive the motor rotor 13 to rotate, thereby driving the motor shaft 11 to rotate to output a driving force.

[0089] In one embodiment, the motor shaft 11 of the steering motor 10 is parallel to the axial direction of the rear wheel 1002 .

[0090] In one embodiment, the lead screw 30 extends in an axial direction parallel to the rear wheel 1002, and the lead screw 30 includes an input end and an output end. The transmission mechanism 20 is used to transmit and connect the motor shaft 11 of the steering motor 10 and the input end of the lead screw 30. The input end of the lead screw 30 is used to receive the drive of the steering motor 10 through the transmission mechanism 20, and the output end of the lead screw 30 is used to transmit and connect to the rear wheel 1002 of the vehicle 1000. The lead screw 30 is used to convert the rotational motion of the motor shaft 11 of the steering motor 10 into a linear displacement along the axial direction of the lead screw 30 and output it to the rear wheel 1002 through the output end to drive the rear wheel 1002 to steer.

[0091] In one embodiment, the transmission mechanism 20 is used to reduce the rotation speed output by the steering motor 10 to increase the torque, thereby ensuring the displacement of the lead screw 30 along its own axial direction, and further ensuring that the lead screw 30 can reliably drive the rear wheel 1002 to achieve steering.

[0092] The lead screw 30 includes a screw rod 31 and a nut 32. The screw rod 31 extends in an axial direction parallel to the rear wheel 1002. The nut 32 is sleeved on the outer peripheral surface of the screw rod 31. The thread of the inner peripheral surface of the nut 32 is meshed with the outer peripheral surface of the screw rod 31. In one embodiment, the screw rod 31 serves as the input end of the lead screw 30, and the nut 32 serves as the output end of the lead screw 30. That is, the screw rod 31 is used to receive the drive of the steering motor 10 through the transmission mechanism 20, and the nut 32 is connected to the rear wheel 1002 of the vehicle 1000. In the process of driving the rear wheel 1002 to steer, the screw rod 31 rotates with the rotation of the motor shaft 11 to drive the nut 32 to move along the axial direction of the screw rod 31, thereby driving the rear wheel 1002 of the vehicle 1000 to steer.

[0093] In another embodiment, the nut 32 serves as the input end of the screw 30, and the screw 31 serves as the output end of the screw 30. That is, the nut 32 is used to receive the drive of the steering motor 10 through the transmission mechanism 20, and the screw 31 is connected to the rear wheel 1002 of the vehicle 1000. In the process of driving the rear wheel 1002 to steer, the nut 32 rotates with the rotation of the motor shaft 11 to drive the screw 31 to move along its own axial direction, thereby driving the rear wheel 1002 of the wheel to steer.

[0094] In one embodiment, the rear wheel steering device 100 provided by the present application includes a steering rod 50, and the steering rod 50 is used to drive and connect the lead screw 30 and the rear wheel 1002. That is, the output end of the lead screw 30 is connected to the rear wheel 1002 of the vehicle 1000 through the steering rod 50. When the rear wheel 1002 of the vehicle 1000 provided by the present application needs to be steered, the motor shaft 11 of the steering motor 10 rotates, and the rear wheel steering device 100 of the present application transmits the driving force of the motor shaft 11 toward the lead screw 30 through the transmission mechanism 20, so that the lead screw 30 is displaced along its own axial direction and pulls the steering rod 50 to move, thereby driving the rear wheel 1002 to deflect relative to the frame 1001, and realizing the steering of the rear wheel 1002.

[0095] In one embodiment, the steering rod 50 is coaxially arranged with the screw 31 of the lead screw 30. Thus, the rear wheel steering device 100 of the present application drives the lead screw 30 to move along its own axial direction and drives the steering rod 50 to move along the axial direction of the lead screw 30, thereby driving the rear wheel 1002 to steer.

[0096] Along the radial direction of the screw 31 of the lead screw 30, the distance between the central axis of the motor shaft 11 of the steering motor 10 and the central axis of the screw 31 of the lead screw 30 is smaller than the radius of the first housing 41 of the steering motor 10. The first housing 41 of the steering motor 10 is a rotating body structure, and the radius of the first housing 41 of the steering motor 10 can be understood as the distance between the central axis of the motor shaft 11 of the steering motor 10 and the outer wall of the first housing 41. For ease of understanding, the distance between the central axis of the motor shaft 11 of the steering motor 10 and the central axis of the screw 31 of the lead screw 30 is defined as d, and the radius of the first housing 41 of the steering motor 10 is defined as r, 0≤d<r. As a result, the screw 31 of the lead screw 30 at least partially overlaps with the first housing 41 of the steering motor 10 along its own radial direction.

[0097] The steering motor 10 of the rear wheel steering device 100 provided in the present application drives the lead screw 30 to rotate through the transmission mechanism 20, thereby driving the rear wheel 1002 of the vehicle 1000 to steer. The transmission mechanism 20 is used to reduce the rotation speed output by the steering motor 10 to increase the torque, thereby ensuring that the lead screw 30 reliably drives the rear wheel 1002 to steer. In order to ensure that the driving force provided by the steering motor 10 can reliably drive the rear wheel 1002 to steer, the radial dimension of the steering motor 10 along the lead screw 30 is relatively large. In the prior art, the radial steering motor 10 and the screw 31 of the lead screw 30 are spaced apart along the lead screw 30, so that the radial dimension of the rear wheel steering device 100 is large. The rear-wheel steering gear 100 provided in the present application utilizes the cooperation between the transmission mechanism 20 and the lead screw 30 to ensure that the rear-wheel steering gear 100 can realize the function of driving the rear wheel 1002 to steer, while at the same time making the screw 31 of the lead screw 30 at least partially overlap with the first housing 41 of the steering motor 10 in the radial direction, thereby compressing the radial spatial dimensions of the rear-wheel steering gear 100 along the lead screw 30, thereby reducing the volume of the rear-wheel steering gear 100 and increasing the internal space of the vehicle 1000.

[0098] Please see Figure 6 , Figure 6 It is a schematic diagram of the partial structure of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0099] In one embodiment, the housing 40 includes a second housing 42 , the transmission mechanism 20 includes a planetary gear transmission mechanism 21 , and the second housing 42 is fixed relative to the vehicle frame 1001 and is used to accommodate the planetary gear transmission mechanism 21 . That is, the second housing 42 is the housing of the transmission mechanism 20 .

[0100] Please see Figures 7 to 9 , Figure 7 This is a schematic diagram of a partially exploded structure of a rear wheel steering device 100 provided in one embodiment of the present application; Figure 8 This is a schematic diagram of a partially exploded structure of a rear wheel steering device provided in one embodiment of the present application; Fig. 9 It is a partial cross-sectional structural schematic diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0101] In one embodiment, the planetary gear transmission mechanism 21 includes a sun gear 211, a planetary gear 212, a planetary gear support 213 and an outer gear ring 214. The number of the planetary gears 212 is multiple, and the multiple planetary gears 212 are arranged around the periphery of the sun gear 211 at intervals along the circumference of the sun gear 211, and are used to mesh with the sun gear 211 for transmission. The sun gear 211 is used to receive the driving rotation of the steering motor 10, that is, the sun gear 211 is used to be connected to the motor shaft 11 of the steering motor 10. The sun gear 211 is also used to drive the planetary gear 212 to rotate. The planetary gear 212 is used to be fixed to the planetary gear support 213, so as to drive the planetary gear support 213 to rotate synchronously under the drive of the sun gear 211. The planetary gear support 213 is used to be connected to the lead screw 30 for transmission, so as to output a driving force to the lead screw 30 to drive the lead screw 30 to rotate. The rear wheel steering device 100 provided in the present application realizes the transmission effect between the steering motor 10 and the lead screw 30 through the planetary gear transmission mechanism 21.

[0102] In one embodiment, the planetary gear support 213 includes an axial hole 2131 and a plurality of receiving grooves 2132, wherein the plurality of receiving grooves 2132 are arranged around the periphery of the axial hole 2131 at intervals along the circumference of the axial hole 2131. The axial hole 2131 is used to accommodate the sun gear 211, and each receiving groove 2132 is used to accommodate a planetary gear 212. The planetary gear support 213 is used to be fixed with the plurality of planetary gears 212 so as to rotate with the rotation of the planetary gears 212.

[0103] The outer ring gear 214 is used to be fixed in the second housing 42 of the rear wheel steering gear 100 of the present application. The outer ring gear 214 is used to be sleeved on the periphery of the multiple planetary gears 212 and the planetary gear bracket 213, and is used to engage with the multiple planetary gears 212 to facilitate supporting the multiple planetary gears 212.

[0104] During the rotation of the motor shaft 11 of the steering motor 10 of the present application, the rotation of the motor shaft 11 drives the sun gear 211 to rotate and drives the multiple planetary gears 212 to rotate. The rotation of the multiple planetary gears 212 synchronously drives the planetary gear bracket 213 to rotate, so as to drive the lead screw 30 to rotate. Corresponding to the embodiment in which the screw 31 of the lead screw 30 is used as the input end of the lead screw 30, the planetary gear bracket 213 is connected to the screw 31 of the lead screw 30 by transmission, and the rotation of the planetary gear bracket 213 drives the screw 31 to rotate, so that the nut 32 is displaced along the axial direction of the screw 31 relative to the screw 31, thereby driving the rear wheel 1002 to turn. Corresponding to the embodiment in which the nut 32 of the lead screw 30 is used as the input end, the planetary gear bracket 213 is connected to the nut 32 of the lead screw 30 by transmission, and the rotation of the planetary gear bracket 213 drives the nut 32 to rotate, so that the screw 31 is displaced along its own axial direction relative to the nut 32, thereby driving the rear wheel 1002 to turn.

[0105] In the embodiment of the present application, the planetary gear transmission mechanism 21 receives the drive of the motor shaft 11 through the sun gear 211 with a smaller radius, and outputs the driving force to the lead screw 30 through the planetary gear support 213 arranged on the periphery of the sun gear 211, thereby enabling the planetary gear transmission mechanism 21 to achieve the effect of deceleration and torque increase, and ensure the reduction ratio of the planetary gear transmission mechanism 21. In addition, since the sun gear 211 and the planetary gear support 213 of the planetary gear transmission mechanism 21 rotate around the same central axis, that is, both rotate around the central axis of the sun gear 211, the input axis and the output axis of the planetary gear transmission mechanism 21 coincide, which can reduce the radial spacing between the central axis of the motor shaft 11 of the steering motor 10 and the central axis of the screw 31. That is, the rear wheel steering device 100 provided in the present application can reduce the radial spacing between the central axis of the motor shaft 11 of the steering motor 10 and the central axis of the screw 31 under the premise of ensuring the reduction ratio of the planetary gear transmission mechanism 21, thereby compressing the overall size of the rear wheel steering device 100 of the present application along the radial direction of the screw 31.

[0106] In one embodiment, the planetary gear transmission mechanism 21 includes three planetary gears 212, which are evenly arranged around the periphery of the sun gear 211 along the circumference of the sun gear 211 and are used for meshing and transmission with the sun gear 211. By setting the number of planetary gears 212 to three, the transmission mechanism 20 can balance the reduction ratio, torque carrying capacity, NVH noise, and installation convenience, thereby improving the overall performance of the rear wheel steering device 100 of the present application.

[0107] It should be noted that the number of planetary wheels 212 in the above-mentioned embodiment is only an exemplary introduction and does not represent the specific number of planetary wheels 212 in other embodiments of the present application. That is, the number of planetary wheels 212 in the present application can be adaptively adjusted according to the actual application scenario. For example, in another embodiment, the number of planetary wheels 212 is four or five. When the planetary gear transmission mechanism 21 includes four planetary wheels 212, the rear-wheel steering gear 100 of the present application can take into account the reduction ratio, torque carrying capacity, NVH noise and installation convenience. When the planetary gear transmission mechanism 21 includes five planetary wheels 212, the torque carrying capacity of the transmission mechanism 20 is larger, which can improve the reliability of the rear-wheel steering gear 100 of the present application.

[0108] Please see Fig.10 , Fig.10 This is a simplified diagram of the transmission structure of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0109] In one embodiment, along the axial direction of the screw 31, the central axis of the motor shaft 11 of the steering motor 10, the central axis of the sun gear 211, and the central axis of the screw 31 of the lead screw 30 coincide in sequence. That is, the steering motor 10, the planetary gear transmission mechanism 21 and the lead screw 30 are coaxially arranged, so that the central axis of the lead screw 30 coincides with the central axis of the steering motor 10. Along the radial direction of the screw 31, the maximum size of the rear wheel steering device 100 of the present application is roughly equal to the size of the first housing 41 of the steering motor 10, which can better limit the overall size of the rear wheel steering device 100 provided by the present application.

[0110] In one embodiment, the motor shaft 11 of the steering motor 10 and the gear shaft of the sun gear 211 are an integrated structure, that is, the motor shaft 11 of the steering motor 10 and the gear shaft of the sun gear 211 are coaxially arranged.

[0111] In one embodiment, the motor shaft 11 of the steering motor 10 is connected to the gear shaft of the sun gear 211 by interference fitting.

[0112] Please see Fig.11 , Fig.11 This is a simplified diagram of the transmission structure of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0113] In one embodiment, along the axial direction of the screw 31, the central axis of the sun gear 211 coincides with the central axis of the screw 31 of the lead screw 30, that is, the planetary gear transmission mechanism 21 is coaxially arranged with the lead screw 30. Along the radial direction of the screw 31, the distance between the central axis of the sun gear 211 and the central axis of the motor shaft 11 of the steering motor 10 is greater than the radius of the motor shaft 11. That is, along the radial direction of the screw 31, the gear shaft of the sun gear 211 and the motor shaft 11 of the steering motor 10 are spaced apart. As a result, the distance between the central axis of the screw 31 and the central axis of the steering motor 10 along the radial direction of the screw 31 is relatively small, and the maximum size of the rear wheel steering gear 100 provided in the present application along the radial direction of the screw 31 is roughly equal to the size of the first housing 41 of the steering motor 10, which can also better limit the overall size of the rear wheel steering gear 100 provided in the present application.

[0114] In one embodiment, the transmission mechanism 20 includes a parallel axis gear transmission mechanism 22, and the parallel axis gear transmission mechanism 22 includes an input wheel 221 and an output wheel 222. The input wheel 221 is used to receive the driving rotation of the steering motor 10, and the input wheel 221 is also used to mesh with the output wheel 222, and the output wheel 222 is used to output the driving force to the sun gear 211 of the planetary gear transmission mechanism 21. In one embodiment, the input wheel 221 is used to be sleeved and fixed on the motor shaft 11, so as to rotate with the motor shaft 11 when the motor shaft 11 rotates. The output wheel 222 is coaxially fixed with the sun gear 211. When the steering motor 10 is working, the input wheel 221 rotates with the rotation of the motor shaft 11, and drives the output wheel 222 to rotate, so as to drive the sun gear 211 to rotate, thereby achieving the effect of outputting the driving force of the steering motor 10 toward the sun gear 211 of the planetary gear transmission mechanism 21.

[0115] In one embodiment, the diameter of the input wheel 221 is smaller than the diameter of the output wheel 222. The parallel axis gear transmission mechanism 22 can form a deceleration effect from the direction of the input wheel 221 to the output wheel 222. Thus, the motor shaft 11 of the steering motor 10 and the sun gear 211 of the planetary gear transmission mechanism 21 can form a first stage of transmission through the parallel axis gear transmission mechanism 22, thereby realizing a first stage of deceleration and torque increase. The planetary wheel support 213 of the planetary gear transmission mechanism 21 and the lead screw 30 can form a second stage of transmission, thereby realizing a second stage of deceleration and torque increase.

[0116] The rear wheel steering gear 100 provided in the present application can achieve two-stage deceleration, thereby significantly reducing the rotation speed of the driving force output by the steering motor 10 and significantly increasing the torque of the driving force output by the steering motor 10. Or it can be understood that the transmission mechanism 20 can increase the reduction ratio through the parallel shaft gear transmission mechanism 22. Thus, on the premise of ensuring that the transmission mechanism 20 has a reliable reduction ratio, the volume of the planetary gear transmission mechanism 21 can be reduced, thereby controlling the overall volume of the transmission mechanism 20, so that the radial dimension of the transmission mechanism 20 along the screw 31 is smaller than the dimension of the first housing 41 of the steering motor 10. The rear wheel steering gear 100 provided in the present application can reduce the overall dimension of the rear wheel steering gear 100 along the radial direction of the screw 31 on the premise of meeting the required output torque. In addition, the parallel shaft gear transmission mechanism 22 also has a higher transmission efficiency, which can improve the overall transmission efficiency of the rear wheel steering gear 100 of the present application.

[0117] It should be noted that, in the above-mentioned embodiment, the transmission mode between the motor shaft 11 of the steering motor 10 and the sun gear 211 in the planetary gear transmission mechanism 21 is only used as an exemplary introduction, that is, the transmission mode between the motor shaft 11 of the steering motor 10 and the sun gear 211 in the planetary gear transmission mechanism 21 of the present application includes but is not limited to parallel shaft gear transmission. For example, in another embodiment, the transmission mechanism 20 includes a transmission wheel and a belt (not shown in the figure), and the transmission wheel is used to receive the driving rotation of the steering motor 10, that is, the transmission wheel is sleeved and fixed on the motor shaft 11. The belt is used to drive and connect the transmission wheel and the sun gear 211 to transmit the driving force of the steering motor 10 to the sun gear 211. When the steering motor 10 is working, the motor shaft 11 drives the transmission wheel to rotate and drives the belt to drive the sun gear 211 to rotate through the transmission wheel, and the effect of outputting the driving force of the steering motor 10 toward the sun gear 211 of the planetary gear transmission mechanism 21 can also be achieved. It can be understood that the structure of the transmission wheel and the belt is relatively simple, which is conducive to the internal structure arrangement of the rear wheel steering device 100 of the present application.

[0118] In one embodiment, the diameter of the transmission wheel is smaller than the diameter of the sun wheel 211 .

[0119] Please see Figure 12 to Figure 14 ,in Fig.12 A schematic diagram of a partial structure of a rear wheel steering device 100 provided in an embodiment of the present application; Fig.13 This is a schematic diagram of a partially exploded structure of a rear wheel steering device 100 provided in one embodiment of the present application; Fig.14 It is a partial cross-sectional structural schematic diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0120] In one embodiment, the planetary wheel bracket 213 is fixedly connected to the screw 31 of the lead screw 30, the nut 32 of the lead screw 30 is meshed with the periphery of the screw 31, and the nut 32 along the axial direction of the screw 31 is used to fix the connection with the steering rod 50 of the rear wheel steering device 100, and the lead screw 30 is used to receive the driving rotation of the planetary gear transmission mechanism 21, and is used to drive the rear wheel 1002 of the vehicle 1000 to steer through the steering rod 50. That is, the screw 31 serves as the input end of the lead screw 30, and the nut 32 serves as the output end of the lead screw 30. In the embodiment of the present application, the nut 32 and the screw 31 of the lead screw 30 are fixedly connected to the steering rod 50 of the vehicle 1000 and the transmission mechanism 20 of the rear wheel steering device 100, respectively. The steering motor 10 of the rear wheel steering gear 100 of the present application drives the screw 31 to rotate through the transmission mechanism 20, so as to drive the nut 32 to drive the steering rod 50 to move along the central axis of the screw 31, so that the rear wheel steering gear 100 can drive the rear wheel 1002 of the vehicle 1000 to steer through the steering rod 50.

[0121] In one embodiment, the planetary gear support 213 includes a sleeve, and along the axial direction of the screw rod 31, the sleeve is located on the side of the planetary gear support 213 away from the steering motor 10. Along the axial direction of the screw rod 31, one end of the screw rod 31 away from the rear wheel 1002 is embedded in the sleeve, so that the planetary gear support 213 and the screw rod 31 are fixedly connected.

[0122] In one embodiment, the planetary wheel bracket 213 is fixedly connected to the nut 32 of the lead screw 30, the nut 32 of the lead screw 30 is meshed with the periphery of the screw 31, and the screw 31 is used to be fixedly connected to the steering tie rod 50 of the rear wheel steering device 100 along the axial direction of the screw 31, and the lead screw 30 is used to receive the driving rotation of the planetary gear transmission mechanism 21, and is used to drive the rear wheel 1002 of the vehicle 1000 to steer through the steering tie rod 50. That is, the nut 32 serves as the input end of the lead screw 30, and the screw 31 serves as the output end of the lead screw 30. In the embodiment of the present application, the nut 32 and the screw 31 of the lead screw 30 are fixedly connected to the transmission mechanism 20 of the rear wheel steering device 100 and the steering tie rod 50 of the vehicle 1000, respectively. The steering motor 10 of the rear wheel steering gear 100 of the present application drives the nut 32 to rotate through the transmission mechanism 20 to drive the screw 31 to drive the steering rod 50 to move axially along the screw 31, so that the rear wheel steering gear 100 can drive the rear wheel 1002 of the vehicle 1000 to steer through the steering rod 50.

[0123] In one embodiment, the second housing 42 is used to accommodate the planetary gear transmission mechanism 21 and to at least partially accommodate the lead screw 30 .

[0124] In one embodiment, the steering rod 50 includes two opposite ends along the axial direction of the screw rod 31. For ease of introduction, the two ends of the steering rod 50 are defined as a first end 51 and a second end 52, respectively. Along the axial direction of the screw rod 31, the first end 51 is located between the transmission mechanism 20 and the second end 52. The first end 51 is used to be embedded in the second housing 42 of the transmission mechanism 20 and is used for transmission connection with the screw rod 30. The second end 52 is used for transmission connection with a rear wheel 1002 of the vehicle 1000, and is used to drive the rear wheel 1002 of the vehicle 1000 to steer.

[0125] That is, the second housing 42 of the transmission mechanism 20 includes a receiving groove. For the sake of convenience, the receiving groove of the second housing 42 is defined as the first receiving groove 43. The planetary gear transmission mechanism 21 and part of the lead screw 30 are received in the first receiving groove 43. Along the axial direction of the screw 31, the notch of the first receiving groove 43 faces the side away from the sun gear 211, and the first end 51 of the steering rod 50 extends into the first receiving groove 43 through the notch of the first receiving groove 43 and is connected to the lead screw 30. In the embodiment of the present application, by partially accommodating the steering rod 50 in the second housing 42 of the transmission mechanism 20, the overall size of the rear wheel steering device 100 of the present application along the axial direction of the screw 31 can be reduced, which is conducive to the miniaturized design of the rear wheel steering device 100 of the present application.

[0126] In one embodiment, the first end 51 of the steering rod 50 is slidably connected to the groove wall of the first accommodating groove 43 along the axial direction of the screw rod 31. That is, the second housing 42 of the transmission mechanism 20 can be used to limit the radial displacement of the steering rod 50 along the screw rod 31 to improve the steering accuracy of the rear wheel steering device 100 of the present application.

[0127] In one embodiment, the steering tie rod 50 includes a receiving groove. For the sake of convenience, the receiving groove of the steering tie rod 50 is defined as a second receiving groove 53. Along the axial direction of the screw rod 31, the notch of the second receiving groove 53 faces the sun gear 211, and the second receiving groove 53 is used to receive a section of the lead screw 30. That is, the first end 51 of the steering tie rod 50 includes the second receiving groove 53, and along the axial direction of the screw rod 31, the end of the lead screw 30 away from the sun gear 211 extends into the second receiving groove 53 through the notch portion of the second receiving groove 53. In the embodiment of the present application, by using the second receiving groove 53 of the steering tie rod 50 to partially receive the lead screw 30, the overall size of the rear wheel steering gear 100 of the present application along the axial direction of the screw rod 31 can be reduced, which is conducive to the miniaturized design of the rear wheel steering gear 100 of the present application.

[0128] In one embodiment, the nut 32 of the lead screw 30 is fixed to the groove wall of the second accommodating groove 53, and the nut 32 is used to receive the drive of the screw rod 31 and to move along the axial direction of the screw rod 31 to drive the steering rod 50. That is, the screw rod 31 serves as the input end of the lead screw 30, and is used to be connected to the planetary gear transmission mechanism 21 to receive the driving rotation of the steering motor 10. The nut 32 serves as the output end of the lead screw 30, and is used to be fixedly connected to the steering rod 50, and is used to receive the drive of the screw rod 31, and moves along the axial direction of the screw rod 31 with the rotation of the screw rod 31 to drive the steering rod 50 to move, thereby driving the rear wheel 1002 to steer.

[0129] In another embodiment, the nut 32 of the lead screw 30 is fixed to the motor shaft 11, and the nut 32 is used to drive the screw 31 to move along its own axial direction with the rotation of the motor shaft 11 and drive the steering rod 50. That is, the nut 32 serves as the input end of the lead screw 30, and is used to be fixedly connected to the motor shaft 11 to receive the driving rotation of the steering motor 10. The screw 31 serves as the output end of the lead screw 30, and is used to be fixedly connected to the steering rod 50, and is used to receive the drive of the nut 32, and moves along its own axial direction with the rotation of the nut 32 to drive the steering rod 50 to move, thereby driving the rear wheel 1002 to steer.

[0130] Please see Figure 15 to Figure 16 ,in Fig.15 A schematic diagram of a partial structure of a rear wheel steering device 100 provided in an embodiment of the present application; Fig.16 It is a schematic diagram of a partially exploded structure of a rear wheel steering gear 100 provided in an embodiment of the present application.

[0131] In one embodiment, the lead screw 30 is a planetary roller lead screw 30a, and the planetary roller lead screw 30a includes a plurality of planetary rollers 33. Along the circumference of the screw 31, the plurality of planetary roller lead screws 30a are spaced around the outer periphery of the screw 31 and are respectively engaged with the screw 31. The nut 32 of the lead screw 30 is transmission-connected to the screw 31 through the plurality of planetary rollers 33.

[0132] That is, each planetary roller 33 includes a first thread segment 331 along the axial direction of the screw 31, and the first thread segment 331 is used to mesh with the thread of the outer peripheral surface of the screw 31, so that the screw 31 can rotate under the drive of the steering motor 10 and drive each planetary roller 33 to rotate, and at the same time drive each planetary roller 33 to move along the axial direction of the screw 31. The nut 32 is sleeved on the outer periphery of the plurality of planetary rollers 33, and the inner wall of the nut 32 along the radial direction of the lead screw 30 is spaced from the first thread segment 331. The plurality of planetary rollers 33 are respectively used to be rotatably connected with the nut 32. That is, each planetary roller 33 can roll around the central axis of the screw 31 in the nut 32, and drive the nut 32 to move along the axial direction of the screw 31.

[0133] In the embodiment of the present application, the first thread segment 331 of the planetary roller 33 cooperates with the thread of the outer peripheral surface of the screw 31, so that the planetary roller 33 and the screw 31 generate line contact rolling friction, which can increase the contact surface and force surface of the planetary roller 33 and the screw 31 during the transmission process. On the one hand, when the steering motor 10 is working, the design can improve the transmission efficiency. On the other hand, when the steering motor 10 stops working, the friction between the planetary roller 33 and the screw 31 is large, which can improve the self-locking ability of the screw 30. When the rear wheel 1002 is impacted by the ground and generates an unexpected turn, the rear wheel 1002 may reversely drive the steering rod 50 to drive the screw 30 to move axially along the screw 31. The rear wheel steering device 100 of the present application can limit the rotation angle of the screw 30 through the self-locking function of the planetary roller screw 30a to limit the axial displacement of the steering rod 50, thereby limiting the angle of the rear wheel 1002 to generate an unexpected turn.

[0134] That is, the rear wheel steering gear 100 provided in the present application can drive the screw 30 to rotate and ensure the transmission efficiency when driven by the steering motor 10 because the planetary roller screw 30a has high transmission efficiency and good self-locking ability, and can limit the rotation of the screw 30 when the steering motor 10 stops driving, thereby preventing the rear wheels 1002 of the vehicle 1000 from making unexpected turns after being impacted.

[0135] In one embodiment, each planetary roller 33 includes two second thread segments 332, and the two second thread segments 332 are arranged on both sides of the first thread segment 331 along the axial direction of the screw rod 31. Each second thread segment 332 is used for threaded engagement transmission with the nut 32. Thus, the threaded engagement between the second thread segments 332 of each planetary roller 33 and the nut 32 can limit the radial displacement of the planetary roller 33 and the nut 32 along the screw rod 31, and avoid radial offset of the planetary roller 33 during the axial movement along the screw rod 31, thereby improving the steering accuracy.

[0136] In one embodiment, the planetary roller screw 30 a includes six planetary rollers 33 .

[0137] In one embodiment, the planetary roller screw 30a includes 10 planetary rollers 33. In the embodiment of the present application, when the planetary roller screw 30a includes 10 planetary rollers 33, the locking ability and installation convenience of the screw 30 can be balanced, and the rear wheel 1002 can be prevented from making an undesired turn due to a small number of planetary rollers 33, and the planetary roller screw 30a can be prevented from being inconvenient to install due to a large number of planetary rollers 33.

[0138] It should be noted that the number of planetary rollers 33 in the above embodiment is only used as an exemplary introduction. The number of planetary rollers 33 in the rear wheel steering gear 100 of the present application can be adaptively adjusted according to the actual application scenario.

[0139] In one embodiment, the nut 32 is fixed to the groove wall of the second accommodating groove 53, and the screw 31 is used to rotate with the transmission mechanism 20 and drive the multiple planetary rollers 33 to move along the axial direction of the screw 31, and the multiple planetary rollers 33 are used to drive the nut 32 to move synchronously. That is, the screw 31 serves as the input end of the lead screw 30 and is used to be connected to the transmission mechanism 20. The nut 32 serves as the output end of the lead screw 30, and the input end and the output end are driven by the multiple planetary rollers 33. The motor shaft 11 of the steering motor 10 is driven to rotate through the transmission mechanism 20 output to drive the screw 31 to rotate around its own axis, thereby driving the multiple planetary rollers 33 to move along the axial direction of the screw 31, and then driving the nut 32 to move synchronously.

[0140] In another embodiment, the nut 32 is fixed to the transmission mechanism 20, and the nut 32 is used to rotate with the transmission mechanism 20 to drive the multiple planetary rollers 33 to rotate around the screw 31, and the multiple planetary rollers 33 are used to drive the screw 31 to move along its own axial direction. That is, the nut 32 serves as the input end of the screw 30, and is used to be connected to the transmission mechanism 20 for transmission. The screw 31 serves as the output end of the screw 30, and the input end and the output end are driven by the multiple planetary rollers 33. The motor shaft 11 of the steering motor 10 is driven to rotate through the transmission mechanism 20 output, so as to drive the nut 32 to rotate around the axis of the screw 31, thereby driving the multiple planetary rollers 33 to rotate around the axis of the screw 31, and then driving the screw 31 to move along its own axial direction.

[0141] In one embodiment, the outer peripheral surface of the screw 31 includes a radial protrusion 311, that is, along the radial direction of the screw 31, the radial protrusion 311 extends from the outer peripheral surface of the screw 31 in a direction away from the screw 31. Along the axial direction of the screw 31, the radial protrusions 311 are arranged at intervals on the side of the nut 32 away from the sun gear 211. It can be understood that when the steering motor 10 is working, the lead screw 30 receives the driving force of the steering motor 10 output through the transmission mechanism 20, so that the nut 32 and the screw 31 are relatively displaced along the axial direction of the screw 31, so as to drive the steering tie rod 50 to move and drive the rear wheel 1002 to steer. In the present application, by radially protruding 311 at the end of the nut 32 away from the sun gear 211 along the radial direction of the screw 31, the radial protrusion 311 can be used to limit the relative displacement of the nut 32 and the screw 31 along the axial direction of the screw 31, so as to prevent the nut 32 and the screw 31 from falling off due to excessive relative displacement between the nut 32 and the screw 31.

[0142] In one embodiment, the diameter of the radial protrusion 311 is greater than the inner diameter of the nut 32, that is, along the radial direction of the screw 31, the distance from the outer wall of the radial protrusion 311 to the central axis of the screw 31 is greater than the radius of the nut 32. In the present application, by setting the diameter of the radial protrusion 311 to be greater than the inner diameter of the nut 32, the radial protrusion 311 can be used to limit the relative displacement between the planetary roller 33 and the nut 32, thereby preventing the planetary roller 33 from falling off from the nut 32 due to excessive relative displacement between the planetary roller 33 and the nut 32.

[0143] In one embodiment, the radial protrusion 311 is used to be embedded in the groove wall of the second receiving groove 53. That is, the radial protrusion 311 is received in the second receiving groove 53 and embedded in the groove wall of the second receiving groove 53 to be fixedly connected with the steering rod 50. Thus, the screw rod 31 can serve as the output end of the lead screw 30, and the screw rod 31 can drive the steering rod 50 to move when the screw rod 31 is displaced relative to the nut 32 along the axial direction of the screw rod 31, thereby driving the rear wheel 1002 to steer. In addition, the groove wall of the second receiving groove 53 can limit the displacement of the screw rod 31 in the radial direction of the screw rod 31 through the radial protrusion 31, thereby preventing the screw rod 31 from deviating, thereby improving the steering accuracy.

[0144] In one embodiment, the rear wheel steering device 100 provided by the present application includes a controller (not shown), which is used to communicate with the steering motor 10. When the rear wheel 1002 of the vehicle 1000 needs to be steered, the controller is used to control the rotation of the motor shaft 11 of the steering motor 10 to drive the transmission mechanism 20 to drive the lead screw 30 to rotate a certain angle, thereby controlling the rear wheel 1002 to rotate a preset angle.

[0145] In one embodiment, after the rear wheel 1002 of the vehicle 1000 completes steering, the controller is also used to drive the motor shaft 11 of the steering motor 10 to continuously rotate, so as to drive the transmission mechanism 20 to hold the screw 30, thereby increasing the supporting torque for the rear wheel 1002 and limiting the rear wheel 1002 from producing unexpected steering.

[0146] In one embodiment, the rear wheel steering device 100 provided in the present application includes a sensor 60, which is fixed on the second housing 42 of the rear wheel steering device 100 of the present application and is used to detect the axial displacement of the lead screw 30. It should be noted that the axial displacement of the lead screw 30 can be the axial displacement of the screw 31, or the displacement of the nut 32 along the axial direction of the screw 31. The steering motor 10 rotates the shaft 11 of the steering motor 10 by a certain angle according to the detection signal of the sensor 60 to control the steering angle of the rear wheel 1002. In the embodiment of the present application, the steering angle of the rear wheel 1002 can be indirectly detected by detecting the displacement of the lead screw 30 through the sensor 60, which is conducive to controlling the rotation angle of the motor shaft 11 of the steering motor 10, thereby ensuring reliable steering of the rear wheel 1002.

[0147] In one embodiment, the sensor 60 is used to transmit the detection signal to the controller, and the controller is used to receive the detection signal output by the sensor 60 and indirectly obtain the steering angle of the rear wheel 1002 through calculation.

[0148] In one embodiment, the sensor 60 includes a displacement sensor, which is fixed to the second housing 42 and is used to directly detect the axial displacement of the lead screw 30 .

[0149] In one embodiment, in response to a first control signal, the steering motor 10 is used to continuously output a first preset torque toward the planetary roller screw 30a, and the first control signal is used to instruct the rear wheel steering gear 100 to drive the rear wheel 1002 of the vehicle 1000 to turn to a preset angle. That is, the sensor 60 is used to detect the axial displacement of the planetary roller screw 30a and output a detection signal to the controller. The controller determines whether to generate the first control signal based on the detection signal of the sensor 60. The first control signal is used to instruct the rear wheel steering gear 100 to drive the rear wheel 1002 of the vehicle 1000 to turn to a preset angle. The controller is also used to drive the steering motor 10 to continuously output a driving force in response to the first control signal, so that the transmission mechanism 20 can hold the planetary roller screw 30a, thereby increasing the support torque on the rear wheel 1002, thereby limiting the rear wheel 1002 from making an unexpected turn. That is, after the rear wheel steering device 100 of the present application drives the rear wheel 1002 to rotate to a preset angle, the steering motor 10 continues to output torque to assist the planetary roller screw 30a to lock the steering rod 50 to prevent the rear wheel 1002 from making an unexpected turn.

[0150] In one embodiment, the first preset torque is equal to the stall torque of the steering motor 10 .

[0151] In one embodiment, the difference between the first preset torque and the stall torque of the steering motor 10 is smaller than the first preset difference.

[0152] Please see Fig.17 and Fig.18 , Fig.17 This is a schematic diagram of a partially exploded structure of a rear wheel steering device 100 provided in one embodiment of the present application; Fig.18 It is a partial cross-sectional structural schematic diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0153] In one embodiment, the screw 30 is a ball screw 30b. That is, the ball screw 30b includes a plurality of balls 34. Along the circumference of the screw 31, a plurality of balls 34 are spaced around the periphery of the screw 31, and the plurality of balls 34 are located between the inner circumference of the nut 32 and the outer circumference of the screw 31, and abut against the inner circumference of the nut 32 and the outer circumference of the screw 31. In the embodiment of the present application, the plurality of balls 34 can reduce the friction between the nut 32 and the screw 31, thereby improving the transmission efficiency of the rear wheel steering device 100 of the present application.

[0154] Please see Fig.19 and Fig. 20 ,in Fig.19 This is a schematic diagram of a partially exploded structure of a rear wheel steering device 100 provided in one embodiment of the present application; Fig. 20 It is a schematic cross-sectional structure diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0155] In one embodiment, the rear wheel steering gear 100 provided in the present application includes a locking mechanism 70. The locking mechanism 70 is used to transmit and connect the motor shaft 11 and the ball screw 30b. The locking mechanism 70 is used to receive the drive of the motor shaft 11 when the steering motor 10 is working to drive the ball screw 30b to move, thereby driving the rear wheel 1002 to turn. The locking mechanism 70 is also used to limit the movement of the ball screw 30b when the steering motor 10 stops working. That is, when the motor shaft 11 of the steering motor 10 rotates, the locking mechanism 70 receives the drive of the motor shaft 11 and drives the ball screw 30b to rotate to generate axial displacement, thereby driving the rear wheel 1002 to turn. When the motor shaft 11 of the steering motor 10 does not rotate, the locking mechanism 70 is used to limit the rotation angle of the ball screw 30b, thereby playing the effect of limiting the axial displacement of the ball screw 30b, so as to limit the angle of unexpected steering caused by the impact of the ground on the rear wheel 1002.

[0156] In the embodiment of the present application, the ball screw 30b has a high transmission efficiency, can rotate and generate axial displacement when driven by the steering motor 10, and improve the overall transmission efficiency of the rear wheel steering device 100 of the present application. The locking mechanism 70 is used to achieve self-locking of the rear wheel steering device 100 to prevent the rear wheel 1002 of the vehicle 1000 from unexpectedly turning after being impacted by the ground.

[0157] In one embodiment, the locking mechanism 70 is used to drive the sun gear 211 connecting the motor shaft 11 and the planetary gear transmission mechanism 21. When the steering motor 10 is working, the locking mechanism 70 is used to receive the drive of the motor shaft 11 and drive the sun gear 211 to rotate, so as to drive the ball screw 30b to rotate and generate axial displacement, thereby driving the rear wheel 1002 to steer. When the steering motor 10 stops working, the locking mechanism 70 is also used to limit the rotation of the sun gear 211 to limit the rotation of the ball screw 30b, thereby limiting the axial displacement of the ball screw 30b, and further limiting the angle of the rear wheel 1002 to generate an unexpected steering.

[0158] Please see Fig.21 and Fig. 22 ,in Fig.21 A schematic diagram of a partial structure of a rear wheel steering device 100 provided in an embodiment of the present application; Fig. 22 It is a partial cross-sectional structural schematic diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0159] In one embodiment, the locking mechanism 70 includes a driving member 71, a one-way clutch 72 and a driven member 73. The driving member 71 is used to be fixedly connected to the motor shaft 11 and is used to receive the driving rotation of the steering motor 10. The one-way clutch 72 is used to drive the driving member 71 and the driven member 73. The one-way clutch 72 is used to link the driving member 71 and the driven member 73, or to release the linkage between the driving member 71 and the driven member 73 and to limit the rotation of the driven member 73 relative to the driving member 71. The driven member 73 is used to drive the ball screw 30b and output the driving force of the steering motor 10 to the ball screw 30b.

[0160] When the rear wheel 1002 of the vehicle 1000 needs to turn, the motor shaft 11 of the steering motor 10 rotates, driving the driving member 71 to rotate synchronously. The one-way clutch 72 links the driving member 71 and the driven member 73, and transmits the drive of the driving member 71 to the driven member 73, so as to drive the driven member 73 to rotate, and then drive the ball screw 30b to rotate to produce axial displacement, thereby driving the rear wheel 1002 to turn. When the vehicle 1000 travels on an uneven road surface and causes the rear wheel 1002 to be impacted by the ground and produce unexpected steering, the rear wheel 1002 will reversely drive the ball screw 30b to displace along its own axial direction, and thereby drive the driven member 73 to rotate. The one-way clutch 72 can release the linkage between the driving member 71 and the driven member 73, and can limit the rotation angle of the driven member 73, so as to apply a locking force to the screw 30, realize the self-locking function of the rear wheel steering device 100, thereby limiting the axial displacement of the screw 30, and then limiting the angle of the rear wheel 1002 to produce unexpected steering.

[0161] In one embodiment, the driven member 73 is used for transmission connection with the ball screw 30b through the transmission mechanism 20. That is, the driven member 73 is used for transmission connection with the sun gear 211, so as to realize the transmission connection effect between the locking mechanism 70 and the ball screw 30b.

[0162] In one embodiment, in response to a second control signal, the steering motor 10 is used to continuously output a second preset torque toward the ball screw 30b, and the second control signal is used to instruct the rear wheel steering device 100 to drive the rear wheel 1002 of the vehicle 1000 to turn to a preset angle. That is, the sensor 60 is used to detect the axial displacement of the ball screw 30b and output a detection signal to the controller. The controller determines whether to generate a first control signal based on the detection signal of the sensor 60. The first control signal is used to instruct the rear wheel steering device 100 to drive the rear wheel 1002 of the vehicle 1000 to turn to a preset angle. The controller is also used to drive the steering motor 10 to continuously output a driving force in response to the first control signal, so that the locking mechanism 70 can hold the transmission mechanism 20 and the ball screw 30b, thereby increasing the support torque for the rear wheel 1002, thereby limiting the rear wheel 1002 from making an unexpected turn. That is, after the rear wheel steering device 100 of the present application drives the rear wheel 1002 to rotate to a preset angle, the steering motor 10 continues to output torque to assist the planetary roller screw 30a to lock the steering rod 50 to prevent the rear wheel 1002 from making an unexpected turn.

[0163] In one embodiment, the second preset torque is less than the first preset torque. Because the locking ability of the locking mechanism 70 is stronger than that of the planetary roller screw 30a, in the embodiment of the present application, the locking mechanism 70 is used to lock the transmission mechanism 20 and the ball screw 30b, so that the frequency of the intervention of the steering motor 10 to limit the unexpected steering of the rear wheel 1002 can be reduced. That is, the steering motor 10 can limit the unexpected steering of the rear wheel 1002 with a smaller output torque. Avoid the phenomenon of limiting the unexpected steering of the rear wheel 1002 by driving the steering motor 10 to work in a locked state for a long time. Thereby extending the service life of the steering motor 10 and saving the energy consumption of the rear wheel steering device 100 provided in the present application.

[0164] Please see Fig.23 , Fig.23 It is a partial cross-sectional structural schematic diagram of a rear wheel steering gear 100 provided in one embodiment of the present application.

[0165] In one embodiment, the rear wheel steering device 100 provided in the present application includes a displacement sensor 61, which is used to detect the displacement of the lead screw 30, and the displacement sensor 61 includes a detection component 611 and a moving component 612. The detection component 611 is fixed to the second housing 42 of the rear wheel steering device 100, and the moving component 612 is fixed to the steering rod 50 of the rear wheel 1002 and moves along the axial direction of the steering rod 50 with the steering rod 50.

[0166] like Fig.23As shown, the detection component 611 of the displacement sensor 61 is fixed on the second housing 42 of the rear wheel steering gear 100 near the end of the steering rod 50, and the moving component 612 of the displacement sensor 61 is fixed at the end of the steering rod 50 of the rear wheel 1002. The displacement sensor 61 can be a magneto-electric induction type or a voltage and current type sensor. This application takes the magneto-electric induction type displacement sensor as an example. When the moving component 612 and the steering rod 50 of the rear wheel 1002 move along the axial direction of the steering rod 50, the detection component 611 can measure the displacement of the moving component 612 through electromagnetic induction, that is, measure the displacement of the steering rod 50, and transmit it to the rear wheel controller for controlling the steering of the rear wheel 1002.

[0167] In the embodiment of the present application, the displacement sensor 61 is installed at the second housing 42 and the end of the steering rod 50, which can effectively reduce the influence of the rotation of the screw 31 and the nut 32 of the screw 30 on the displacement measurement of the steering rod 50, ensure the accuracy of the measurement, and at the same time be more conducive to the installation and maintenance of the sensor 60.

[0168] In one embodiment, the detection component 611 and the moving component 612 of the displacement sensor 61 are spaced apart from each other along the radial direction of the screw rod 31. This can prevent the moving component 612 from generating friction with the detection component 611 during the movement of the steering tie rod 50, thereby ensuring the detection accuracy of the displacement sensor 61 and extending its service life.

[0169] In one embodiment, the rear wheel steering device 100 provided in the present application includes two transmission mechanisms 20 and two lead screws 30. The central axes of the two lead screws 30 coincide, and the two lead screws are arranged on both sides of the steering motor 10 along their own axial direction. The two transmission mechanisms 20 are arranged on both sides of the steering motor 10 along the axial direction of the lead screw 30. The steering motor 10 includes two motor shafts 11, and the two motor shafts 11 are arranged on both sides of the motor stator 12 of the steering motor 10, and each motor shaft 11 is used to drive a lead screw 30 through a transmission mechanism 20 to drive the rear wheel 1002 on one side of the vehicle 1000 to achieve steering.

[0170] It should be noted that the number of motor shafts 11 of the steering motor 10 in the above-mentioned embodiment is only introduced as an example. For example, in another embodiment, the steering motor 10 of the present application includes a motor shaft 11, and the rear wheel steering gear 100 of the present application includes two transmission mechanisms 20 and two screws 30. The motor shaft 11 of the steering motor 10 is used to pass through the inner hole of the motor rotor 13 and to drive the two transmission mechanisms 20 respectively. The two transmission mechanisms 20 respectively transmit the driving force to a corresponding screw 30, thereby driving the rear wheel 1002 on the corresponding side to steer.

[0171] Please see Fig.24 , Fig.24 Schematic diagram of the architecture of a vehicle 1000 provided in one embodiment of the present application.

[0172] In one embodiment, the rear wheel steering device 100 provided in the present application includes two steering motors 10, two transmission mechanisms 20 and two lead screws 30. The two steering motors 10 are arranged in an axially spaced relationship along the lead screws 30, and each steering motor 10 is used to drive a lead screw 30 through a transmission mechanism 20 to drive the rear wheel 1002 on one side of the vehicle 1000 to steer.

[0173] In one implementation, the rear wheel steering gear 100 provided in the present application includes two locking mechanisms 70. Along the axial direction of the lead screw 30, the two locking mechanisms 70 are arranged on both sides of the steering motor 10. Each locking mechanism 70 is used to drive the steering motor 10 and a lead screw 30, and each locking mechanism 70 is used to receive the drive of the motor shaft 11 when the steering motor 10 is working to drive a lead screw 30 on the corresponding side to move, thereby driving the rear wheel 1002 on the corresponding side to steer. Each locking mechanism 70 is also used to limit the movement of a lead screw 30 on the corresponding side when the steering motor 10 stops working.

[0174] In one implementation, the screws 31 of the two lead screws 30 have the same thread rotation direction, and the two rear wheels 1002 have the same rotation direction.

[0175] In one implementation, the screws 31 of the two lead screws 30 have opposite thread rotation directions, and the two rear wheels 1002 turn in opposite directions. That is, along the axial direction of the rear wheel 1002, the screws 31 of the two lead screws 30 have opposite thread rotation directions, so that when the steering motor 10 is working, the steering motor 10 can drive the lead screws 30 on both sides of the steering motor 10 to rotate in opposite directions, so that the two rear wheels 1002 on both sides of the vehicle 1000 turn in opposite directions, so as to adjust the relative shape of the two rear wheels 1002, so that the vehicle 1000 can be suitable for different application scenarios.

[0176] In one embodiment, the steering motor 10 drives the lead screws 30 on both sides of the steering motor 10 to rotate in opposite directions, and causes the two rear wheels 1002 on both sides of the vehicle 1000 to deflect relative to each other to form an "outward eight" shape. This shape can reduce the turning radius of the vehicle 1000 and improve the flexibility of the vehicle 1000.

[0177] In one embodiment, the steering motor 10 drives the lead screws 30 on both sides of the steering motor 10 to rotate in opposite directions, and the two rear wheels 1002 on both sides of the vehicle 1000 are relatively deflected to form an "inward eight" shape. This shape can improve the vehicle 1000's ability to resist lateral disturbances, increase the vehicle 1000's stability, and reduce the braking distance.

[0178] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of protection of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A rear wheel steering gear, characterized in that: The rear wheel steering gear includes a steering motor, a transmission mechanism and a lead screw. The steering motor is used to drive the lead screw to steer the rear wheels of the vehicle after the rotation speed is changed by the transmission mechanism. The distance between the central axis of the motor shaft of the steering motor and the central axis of the screw of the lead screw along the radial direction of the screw of the lead screw is smaller than the housing radius of the steering motor.

2. The rear wheel steering gear according to claim 1, characterized in that: The transmission mechanism includes a planetary gear transmission mechanism, the sun gear of the planetary gear transmission mechanism is used to receive the driving rotation of the steering motor, the planetary gears of the planetary gear transmission mechanism are used to mesh with the sun gear and output the driving rotation through the planetary gear support of the planetary gear transmission mechanism, and the outer ring gear of the planetary gear transmission mechanism is used to be fixed to the housing of the rear wheel steering gear and mesh with the planetary gears.

3. The rear wheel steering gear according to claim 2, characterized in that: Along the axial direction of the screw, the central axis of the motor shaft of the steering motor, the central axis of the sun gear, and the central axis of the screw of the lead screw coincide in sequence.

4. The rear wheel steering gear according to claim 2, characterized in that: Along the axial direction of the screw, the central axis of the sun gear coincides with the central axis of the screw of the lead screw; along the radial direction of the screw, the distance between the central axis of the sun gear and the central axis of the motor shaft of the steering motor is greater than the radius of the motor shaft.

5. The rear wheel steering gear according to claim 4, characterized in that: The transmission mechanism includes a parallel axis gear transmission mechanism, the input wheel of the parallel axis gear transmission mechanism is used to receive the driving rotation of the steering motor, the output wheel of the parallel axis gear transmission mechanism is used to mesh with the input wheel and drive the sun wheel to rotate by being coaxially fixed with the sun wheel, and the diameter of the input wheel is smaller than the diameter of the output wheel.

6. The rear wheel steering gear according to any one of claims 2 to 5, characterized in that: The planetary wheel bracket is fixedly connected to the screw of the lead screw, and the nut of the lead screw is engaged with the periphery of the screw. The nut is used to fix the steering rod of the rear wheel steering gear along the axial direction of the screw. The lead screw is used to accept the driving rotation of the planetary gear transmission mechanism and to drive the rear wheels of the vehicle to steer through the steering rod.

7. The rear wheel steering gear according to any one of claims 2 to 5, characterized in that: The planetary wheel bracket is fixedly connected to the nut of the lead screw, and the nut of the lead screw is engaged with the periphery of the screw. The screw is used to fix the steering rod of the rear wheel steering gear along the axial direction of the screw. The lead screw is used to accept the driving rotation of the planetary gear transmission mechanism and to drive the rear wheels of the vehicle to steer through the steering rod.

8. The rear wheel steering gear according to any one of claims 2 to 7, characterized in that: The planetary gear transmission mechanism includes three planetary gears.

9. The rear wheel steering gear according to any one of claims 1 to 8, characterized in that: The lead screw is a planetary roller lead screw, which includes a plurality of planetary rollers, which surround the screw at intervals along the circumference of the screw and are respectively engaged with the screw, and the nut of the lead screw is drivingly connected to the screw through the plurality of planetary rollers, wherein: The planetary roller screw includes 10 planetary rollers.

10. The rear wheel steering gear according to claim 9, characterized in that: In response to a first control signal, the steering motor is used to continuously output a first preset torque toward the planetary roller screw, and the first control signal is used to instruct the rear wheel steering gear to drive the rear wheels of the vehicle to turn to a preset angle.

11. The rear wheel steering gear according to any one of claims 1 to 8, characterized in that: The screw is a ball screw, and the rear wheel steering gear includes a locking mechanism, which is used to transmit and connect the motor shaft and the ball screw. The locking mechanism is used to accept the drive of the motor shaft to drive the ball screw to move when the steering motor is working. The locking mechanism is also used to limit the movement of the roller screw when the steering motor stops working.

12. The rear wheel steering gear according to claim 11, characterized in that: The locking mechanism includes a driving member, a one-way clutch and a driven member, wherein the driving member is used to be fixedly connected to the motor shaft, the driven member is used to be connected to the ball screw transmission, and the one-way clutch is used to limit the movement of the driven member and to accept the drive of the driving member and drive the driven member.

13. The rear wheel steering gear according to claim 11 or 12, characterized in that: In response to a second control signal, the steering motor is used to continuously output a second preset torque toward the ball screw, and the second control signal is used to instruct the rear wheel steering gear to drive the rear wheels of the vehicle to turn to a preset angle.

14. The rear wheel steering gear according to any one of claims 1 to 13, characterized in that: The rear wheel steering gear includes a displacement sensor, which is used to detect the displacement of the lead screw, wherein: The detection component of the displacement sensor is fixed to the housing of the rear wheel steering gear, and the moving component of the displacement sensor is fixed to the steering rod of the rear wheel and moves along the axial direction of the steering rod.

15. A vehicle, characterized in that: The vehicle comprises: one or more rear wheels; The rear wheel steering gear according to any one of claims 1 to 14, wherein the rear wheel steering gear is used to drive the steering of the one or more rear wheels.

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