Rear wheel steering gear and vehicle

Abstract

The rear wheel steering gear comprises a steering motor, a transmission mechanism and a lead screw, the steering motor is used for driving a screw rod of the lead screw to move axially through the transmission mechanism, and one end of the screw rod is used for driving a rear wheel on one side of the vehicle to steer through a steering tie rod. The other end of the screw rod is used for receiving driving of the transmission mechanism through a nut of the lead screw, and the central axis of a motor shaft of the steering motor is used for being parallel to the central axis of the screw rod; the distance between the central axis of the motor shaft and the central axis of the screw in the arrangement direction of the screw and the steering motor is larger than the radius of a stator outer ring of the steering motor. According to the rear wheel steering gear, the steering motor and the lead screw are arranged in the radial direction of the lead screw, when the two rear wheel steering gears are installed on the frame of the vehicle to drive the two rear wheels respectively, the transverse occupied space of the rear wheel steering gears in the vehicle can be reduced, the structure is compact, and the installation space is saved.

Description

Technical Field

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

[0002] During vehicle operation, the wheel steering system plays a crucial role in vehicle handling, stability, and safety. Currently, rear-wheel steering systems are typically centralized, using a single steering mechanism to synchronously control the steering angles of both rear wheels. This structure has numerous limitations, including slow response speed and difficulty in accurately adjusting the rear-wheel steering angle based on the vehicle's driving state and the driver's intended operation. Summary of the Invention

[0003] The present application provides a rear-wheel steering gear and a vehicle, wherein the steering motor and the lead screw of the rear-wheel steering gear are arranged radially along the lead screw. When two rear-wheel steering gears are installed on the vehicle frame to drive the two rear wheels respectively, the lateral space occupied by the rear-wheel steering gear in the vehicle can be reduced, the structure is compact, and installation space is saved.

[0004] In the first aspect, the present application provides a rear-wheel steering gear, which includes a steering motor, a transmission mechanism and a lead screw, wherein the steering motor is used to drive the screw of the lead screw to move axially through the transmission mechanism, one end of the screw is used to drive the steering of one side of the vehicle through the steering tie rod, and the other end of the screw is used to receive the drive of the transmission mechanism through the nut of the lead screw, wherein: the central axis of the motor shaft of the steering motor is used to be arranged parallel to the central axis of the screw, and the distance between the central axis of the motor shaft and the central axis of the screw along the arrangement direction of the screw and the steering motor is greater than the radius of the stator outer ring of the steering motor.

[0005] The present application provides a distributed rear-wheel steering gear for driving the two rear wheels of a vehicle to steer separately, forming a distributed rear-wheel steering gear, realizing steering decoupling of the two rear wheels, and realizing steering modes such as outward-facing or inward-facing steering in response to different driving environments of the vehicle, enabling the vehicle to make better steering choices to match the current environment; and; the steering motor and the lead screw of the rear-wheel steering gear are arranged along the radial direction of the lead screw. When two rear-wheel steering gears are installed on the frame of the vehicle to drive the two rear wheels separately, the lateral space occupied by the rear-wheel steering gear in the vehicle can be reduced, the structure is compact, and installation space is saved; the two rear-wheel steering gears can be arranged at intervals along the line connecting the two rear wheels, thereby improving the force balance of the frame after the rear-wheel steering gear is installed in the vehicle, and also improving the symmetry of the installation of various components in the vehicle. The axis of the steering motor is parallel to the axis of the screw of the lead screw. The steering motor and the lead screw can be driven by a transmission mechanism, allowing the steering motor to extend in a direction parallel to the screw. This prevents the rear-wheel steering gear from occupying too much space in a direction perpendicular to the axis of the lead screw, thereby forming an irregular shape. This facilitates spatial coordination between the rear-wheel steering gear and other structures after installation within the vehicle. Furthermore, the radial spacing between the central axis of the motor shaft and the central axis of the screw is greater than the radius of the outer ring of the steering motor's stator, ensuring that no installation interference occurs between the steering motor and the screw. The rotation of the motor shaft drives the screw nut to rotate via the transmission mechanism, and the rotation of the nut drives the axial displacement of the screw to drive rear-wheel steering.

[0006] In one possible implementation, the transmission mechanism includes two transmission wheels and a belt, the motor shaft of the steering motor is used to drive one of the two transmission wheels to rotate, the one transmission wheel is used to drive the other of the two transmission wheels to rotate through the belt, and the other transmission wheel is used to drive the nut to rotate.

[0007] This application transmits the rotation of the steering motor to the nut of the screw through a belt, and the motor shaft drives the nut to rotate through the belt transmission to drive the two rear wheels to steer. The transmission is stable, the noise generated during transmission is small, and the structural setting is simple. The axial and radial volume occupied is small, which can match the radial spacing between the steering motor and the screw, reducing the space occupied by the rear wheel steering gear in the vehicle.

[0008] In one possible implementation, the rear wheel steering gear includes a bearing, the inner ring of the bearing is fixedly connected to the nut, the outer ring of the bearing is used to fix the housing of the rear wheel steering gear, the other transmission wheel is sleeved on the outer periphery of the nut, and the bearing is used to be coaxially arranged in sequence with the other transmission wheel along the axial direction of the screw.

[0009] Sleeving another transmission wheel ring around the outer circumference of the nut can increase the connection area between the other transmission wheel and the nut, maintain a force balance between the transmission wheel and the nut at the contact surface, and ensure the stability of the other transmission wheel in driving the nut's rotation. Bearings provided on the outer circumference of the nut support the nut and the housing, ensuring the stability of the nut's rotation within the housing, and preventing the nut's rotation axis from deviating. Furthermore, the nut requires a certain axial length to accommodate the screw for transmission. Sleeving another transmission wheel ring around the outer circumference of the nut utilizes the axial space of the nut without further increasing the total axial length of the nut and the other transmission wheel, thereby reducing the axial length of the rear wheel steering gear.

[0010] In a possible implementation, the other transmission wheel and the bearing are arranged along the direction of the one transmission wheel toward the motor shaft, and the projection of the motor shaft and the bearing at least partially overlap along the direction of the motor shaft toward the screw.

[0011] In this embodiment, the bearing and the motor shaft are arranged on the same axial side of the transmission mechanism, and the projection of the motor shaft in the direction toward the screw at least partially overlaps with the bearing. The concave structure formed by the motor shaft between the transmission mechanism and the stator is used to accommodate the protruding bearing, which can reasonably utilize the various spaces of the rear wheel steering gear, reduce the size of the rear wheel steering gear in the direction toward the screw of the motor shaft, and reduce the space occupied by the rear wheel steering gear in the vehicle.

[0012] In one possible implementation, the lead screw is a trapezoidal lead screw, and the thread lead angle of the screw of the trapezoidal lead screw is less than or equal to 4.5 degrees.

[0013] The nut and screw of the trapezoidal screw are directly engaged through threads, without complex structures such as complex balls and circulation devices. The manufacturing process is relatively easy, the production cost is low, and it is also easy to install and maintain. In addition, the thread lead angle of the screw of the trapezoidal screw can be designed so that the trapezoidal screw can be designed to meet the load-bearing capacity and self-locking requirements required in the current rear wheel steering gear. In addition, the thread lead angle of the screw of the trapezoidal screw is less than or equal to 4.5 degrees. The trapezoidal screw has a locking function: when the vehicle is parked, the locking mechanism of the trapezoidal screw is locked to prevent accidental steering of the rear wheels, providing additional parking protection. When the steering of a single rear wheel fails, the locking mechanism of the trapezoidal screw is locked and the screw is locked in the current position, which helps to maintain the stability of the direction of the rear wheel and prevent deviation from affecting the driving safety of the vehicle.

[0014] In a possible implementation, the screw is a ball screw, and the balls of the ball screw are accommodated between the nut and the screw.

[0015] The space between the nut and the screw of a ball screw is filled with balls. As the nut and screw rotate relative to each other, the balls roll between them, improving lubrication between the two and reducing friction loss. This results in high transmission efficiency. The motor shaft drives the nut via a belt and two drive pulleys. The other drive pulley is coaxially fixed to the ball screw nut. The motor shaft drives one drive pulley, which in turn rotates the other drive pulley via a belt, which in turn drives the ball screw nut. The ball screw nut precisely converts the steering motor's rotation into linear motion, driving the rear wheel and enabling precise adjustment of the rear wheel steering angle. Furthermore, the ball screw efficiently converts the steering motor's torque into linear thrust, transmitting it to the steering tie rods. This ensures rapid response to steering commands, especially in situations requiring rapid changes in vehicle direction, such as emergency avoidance maneuvers. This ensures sufficient steering force output and timely steering action, making it highly effective in distributed rear-wheel steering mechanisms.

[0016] In one possible implementation, the rear wheel steering gear includes a locking mechanism, the steering motor is used to connect to the transmission mechanism through the locking mechanism, the transmission mechanism is used to drive the nut of the screw to rotate, and the locking mechanism is used to limit the rotation of the transmission mechanism when the steering motor stops rotating.

[0017] By designing a distributed rear-wheel drive, two rear-wheel steering gears control the two rear wheels separately, and each rear-wheel steering gear is independently equipped with a corresponding locking mechanism. This allows the two rear-wheel steering gears to drive and lock the steering angles of the two rear wheels separately under the distributed drive design. This decouples the steering of the left and right rear wheels while also controlling the steering angles of both wheels to prevent a single rear wheel from accidentally turning too far and reducing the vehicle's driving stability. Therefore, locking mechanisms are provided for both rear wheels to provide protection. In addition, having different locking mechanisms for the two rear wheels also makes it easier to coordinate the two. The controller can coordinate the rotation angles of the two locking mechanisms, and in conjunction with the corresponding control methods, prevent excessive deviation in the steering angles of the two rear wheels from affecting driving safety and the life of the vehicle's structure. Furthermore, when the lead screw is a trapezoidal lead screw, it forms a double locking structure in conjunction with the locking mechanism, providing dual protection for the steering accuracy of the vehicle's two rear wheels.

[0018] In one possible implementation, the locking mechanism includes a movable member and an output shaft, the output shaft being configured to drive the connection between the motor shaft and the transmission mechanism, and the movable member being configured to move closer to or further away from the output shaft to lock or release the output shaft from rotation. The movable member and the output shaft are locked by approaching each other. The movable member drives the connection between the motor shaft and the output shaft to transmit rotation of the motor shaft, thereby driving rotation of the output shaft, and thereby driving rotation of the transmission mechanism. When the movable member moves away from the output shaft, it restricts rotation of the output shaft, thereby limiting axial displacement of the lead screw.

[0019] In one possible implementation, the screw includes a planetary roller screw, and the thread lead angle of the screw of the planetary roller screw is less than 7 degrees.

[0020] The planetary roller screw used in this embodiment has a screw shaft with a small lead angle non-circular arc thread and can be made of high-friction material, which is conducive to achieving higher lead accuracy, realizing precise micro-feeding, and has a self-locking function. During the long-term use of the vehicle's rear-wheel steering system, the planetary roller screw can always maintain high-precision steering control and reduce the problem of reduced steering accuracy due to wear; the thread lead angle of the screw of the planetary roller screw is less than 7 degrees, and no external locking mechanism is required, thereby reducing the axial size of the rear-wheel steering gear.

[0021] In one possible implementation, the planetary roller screw includes 8-14 rollers, which are radially located between the nut and the screw. The rollers are spaced circumferentially along the screw. The rollers are evenly distributed between the nut and the screw and spaced circumferentially. Any two adjacent rollers are threadedly engaged, and each roller is threadedly engaged with both the nut and the screw. This improves the stability and accuracy of the planetary roller screw transmission, prevents roller misalignment or even deviation during rotation, and enhances the stability of the self-locking function.

[0022] In one possible implementation, the transmission mechanism includes two gears, and the motor shaft drives the nut to rotate by meshing the two gears. The two gears can have different diameters, thereby forming a specific transmission ratio. This gear transmission provides a more precise transmission ratio, a more compact gear structure, high transmission efficiency, and a wide range of power and speed transmission.

[0023] In one possible implementation, the rear wheel steering gear includes a locking mechanism, the steering motor is used to connect one of the gears through the locking mechanism, and the locking mechanism is used to limit the rotation of the two gears when the steering motor stops rotating.

[0024] By designing a distributed rear-wheel drive, the two rear-wheel steering gears control the two rear wheels respectively, and the two rear-wheel steering gears are independently provided with corresponding locking mechanisms. In this way, under the distributed drive design, the two rear-wheel steering gears drive and lock the steering angles of the two rear wheels respectively, achieving the steering decoupling of the left and right rear wheels while also controlling the steering angles of the two wheels to prevent the accidental steering angle of a single rear wheel from being too large, thereby reducing the stability of the vehicle. Therefore, locking mechanisms are provided for protection of both rear wheels. In addition, the different locking mechanisms corresponding to the two rear wheels also make it easier to achieve coordination between the two. The rotation angles of the two locking mechanisms can be coordinated through the controller to cooperate with the corresponding control method to prevent the steering angles of the two rear wheels from deviating too much, affecting driving safety and the life of the vehicle structure.

[0025] In one possible implementation, the rear wheel steering gear includes a controller, which is used to control the operation of the steering motor. The housing of the steering motor includes a accommodating cavity and a partition, the accommodating cavity is used to accommodate the controller of the steering motor, and the partition is used to separate the stator and the controller.

[0026] In one possible implementation, the rear-wheel steering system includes a linear displacement sensor for detecting the axial displacement of the lead screw. The linear displacement sensor is a magnetoelectric displacement sensor. A magnetoelectric displacement sensor, also known as an electromagnetic induction displacement sensor, uses changes in electromagnetic coupling caused by changes in the distance between the sensor and the lead screw to infer the distance the lead screw has moved relative to the sensor. The magnetoelectric displacement sensor allows for a measurement method that avoids direct contact with the lead screw, resulting in high detection sensitivity and accuracy, and prevents the sensor from interfering with the movement of the lead screw.

[0027] In the second aspect, the present application provides a vehicle comprising two rear wheels and at least two rear wheel steering gears, wherein the two rear wheel steering gears are respectively used to drive the steering of the rear wheels on both sides of the vehicle, and the vehicle realizes the outward or inward turning of the two rear wheels through the rear wheel steering gears.

[0028] The vehicle includes two rear wheels and at least two rear wheel steering gears, the two rear wheel steering gears are fixed to the frame and arranged between the two rear wheels, each of the two rear wheel steering gears is used to drive one of the two rear wheels to steer; each rear wheel steering gear includes a steering motor and a screw, and the steering motor, the screw and the rear wheel are arranged in sequence along the arrangement direction of the rear wheel steering gear and the rear wheel correspondingly connected to it, and the steering motor drives the rear wheel to steer through the screw. The present application provides a vehicle with distributed rear wheel steering drive, and the two rear wheel steering gears respectively control the two rear wheels to achieve distributed drive. The axis of the driving motor and the axis of the screw of the screw are parallel, and the steering motor and the screw can be transmitted through a transmission mechanism so that the steering motor can extend in a direction parallel to the screw, preventing the rear wheel steering gear from occupying too much space in the direction perpendicular to the axis of the screw, causing the rear wheel steering gear to form an irregular shape, which is beneficial to the spatial coordination of the rear wheel steering gear with other structures after installation in the vehicle.

[0029] In one possible implementation, along the height of the vehicle, the distance between the central axis of the motor shaft and the axis of the rear wheel is equal to the distance between the central axis of the screw and the axis of the rear wheel. In the horizontal direction of the vehicle during normal driving, the steering motor and the screw of the lead screw of the rear-wheel steering gear are also arranged horizontally, and the axes of the steering motor and the screw are parallel to the line connecting the two rear wheels of the vehicle. This can reduce the height space occupied by the rear-wheel steering gear within the vehicle, thereby reducing the height of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of an electric vehicle provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a distributed rear-wheel drive provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of the rear wheels turning inward in an embodiment of the present application;

[0033] Figure 4 A schematic diagram of the rear wheels turning outward in an outward-facing direction provided in an embodiment of the present application;

[0034] Figure 5 A schematic diagram of the steering structure provided in an embodiment of the present application;

[0035] Figure 6 A cross-sectional schematic diagram of a steering gear provided in an embodiment of the present application;

[0036] Figure 7 This is a schematic diagram of the connection between the steering motor, locking mechanism, transmission mechanism and lead screw in the embodiment of the present application;

[0037] Figure 8 This is an exploded schematic diagram of the nut and the transmission wheel provided in the embodiment of the present application;

[0038] Figure 9 This is a schematic structural diagram of a trapezoidal lead screw in an embodiment of the present application;

[0039] Figure 10 This is a schematic structural diagram of a planetary roller screw in an embodiment of the present application;

[0040] Figure 11 This is a schematic diagram of the exploded structure of the locking mechanism provided in an embodiment of the present application;

[0041] Figure 12 This is a schematic diagram of the assembly structure of the locking mechanism provided in an embodiment of the present application;

[0042] Figure 13 A schematic structural diagram of a rear wheel steering gear provided in an embodiment of the present application;

[0043] Figure 14 An exploded schematic diagram of the end cover and the housing provided in an embodiment of the present application;

[0044] Figure 15 A schematic cross-sectional view of a housing and an end cover provided in an embodiment of the present application;

[0045] Figure 16 For this application Figure 6 A magnified view of a part of the area;

[0046] Figure 17 This is a schematic diagram of the arrangement of two rear wheel steering gears in an embodiment of the present application;

[0047] Figure 18 Schematic diagram of the lead screw and steering yoke. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0049] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of this application are explained and described below.

[0050] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0051] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" mentioned in this application includes direct and indirect connections unless otherwise specified. In the description of this application, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "front", "back", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0052] During vehicle operation, the wheel steering system plays a vital role in vehicle handling, stability, and safety. Currently, rear-wheel steering systems are typically centralized, with a single steering mechanism typically used to synchronously control the steering angles of both rear wheels. This structure has numerous limitations, including slow response times, making it difficult to accurately and quickly adjust the rear-wheel steering angle based on the vehicle's driving state and the driver's intended operation. Furthermore, under complex road conditions, the centralized structure limits the flexibility required to independently control each rear wheel, compromising the vehicle's maneuverability and stability. Furthermore, if the centralized steering mechanism fails, the entire rear-wheel steering function will be severely impacted or even rendered inoperable, significantly reducing vehicle reliability. With the continuous advancement of automotive technology, demands for vehicle handling performance and intelligence are becoming increasingly stringent. The existing centralized rear-wheel steering structure is no longer able to meet these requirements. Migrating from a centralized to a distributed rear-wheel steering structure presents numerous challenges, including steering efficiency, safety, and overall vehicle layout.

[0053] The present application provides a rear-wheel steering gear, which is used to be fixed in pairs on the frame of a vehicle to drive the steering of the rear wheels on both sides of the vehicle respectively. The rear-wheel steering gear includes a steering motor, a transmission mechanism and a lead screw. The steering motor is used to drive the axial movement of the screw of the lead screw through the transmission mechanism. One end of the screw is used to drive the steering of one side of the rear wheel of the vehicle through the steering tie rod, and the other end of the screw is used to receive the drive of the transmission mechanism through the nut of the lead screw, wherein: the central axis of the motor shaft of the steering motor is used to be arranged parallel to the central axis of the screw, and the distance between the central axis of the motor shaft and the central axis of the screw along the arrangement direction of the screw and the steering motor is greater than the radius of the outer ring of the stator of the steering motor. The present application provides a distributed rear-wheel steering gear for driving the two rear wheels of a vehicle to steer separately, forming a distributed rear-wheel steering gear, realizing steering decoupling of the two rear wheels, and realizing steering modes such as outward-facing or inward-facing steering in response to different driving environments of the vehicle, enabling the vehicle to make better steering choices to match the current environment; and; the steering motor and the lead screw of the rear-wheel steering gear are arranged along the radial direction of the lead screw. When two rear-wheel steering gears are installed on the frame of the vehicle to drive the two rear wheels separately, the lateral space occupied by the rear-wheel steering gear in the vehicle can be reduced, the structure is compact, and installation space is saved; the two rear-wheel steering gears can be arranged at intervals along the line connecting the two rear wheels, thereby improving the force balance of the frame after the rear-wheel steering gear is installed in the vehicle, and also improving the symmetry of the installation of various components in the vehicle. The axis of the steering motor is parallel to the axis of the screw of the lead screw. The steering motor and the lead screw can be driven by a transmission mechanism, allowing the steering motor to extend in a direction parallel to the screw. This prevents the rear-wheel steering gear from occupying too much space in a direction perpendicular to the axis of the lead screw, thereby forming an irregular shape. This facilitates spatial coordination between the rear-wheel steering gear and other structures after installation within the vehicle. Furthermore, the radial spacing between the central axis of the motor shaft and the central axis of the screw is greater than the radius of the outer ring of the steering motor's stator, ensuring that no installation interference occurs between the steering motor and the screw. The rotation of the motor shaft drives the screw nut to rotate via the transmission mechanism, and the rotation of the nut drives the axial displacement of the screw to drive rear-wheel steering.

[0054] The present application provides a vehicle, including a two-wheeled, three-wheeled, or four-wheeled vehicle. In one embodiment, the vehicle includes an electric vehicle, which includes a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), and a range-extended electric vehicle (REEV).

[0055] Figure 1 Schematic diagram of an electric vehicle provided in an embodiment of the present application. Figure 1As shown, electric vehicle 1 includes a powertrain 10, a frame 20, and a power battery 30. Frame 20 is used to secure the power battery 30 and powertrain 10. Frame 20 serves as the structural framework of the electric vehicle, supporting and securely connecting the powertrain 10 and the power battery 30, and withstanding the loads of the vehicle's internal and external systems. Powertrain 10 receives electrical energy from the power battery 30 and converts it into mechanical energy to drive wheels 40 for steering.

[0056] In one embodiment, the powertrain 10 includes a steering motor and a steering motor controller. The steering motor controller is used to control the power output of the steering motor and drive the steering motor to rotate, thereby driving the lead screw and tie rod to steer the vehicle's rear wheels 41. The powertrain 10 provided in this application can provide driving force to steer the rear wheels 41 while also having low power consumption and a long service life.

[0057] In one embodiment, the wheels 40 include two rear wheels 41 and the aforementioned rear wheel steering mechanism. Each rear wheel steering mechanism is used to steer one rear wheel 41. Alternatively, the present application provides a vehicle including two rear wheels 41 and the aforementioned powertrain 10, which is used to output power and steer one or more rear wheels 41.

[0058] The present application provides a vehicle with a rear wheel 41 steering function. When the vehicle turns at low speed, such as when turning left, the front wheel deflects to the left under the influence of the steering wheel, and the right rear wheel 41 deflects in the opposite direction of the front wheel, that is, to the right. This can effectively reduce the turning radius and adapt to turning scenarios with limited space, such as turning on the road or parking in a parking lot. When the vehicle changes lanes at high speed, such as when changing lanes to the left, the rear wheel 41 will turn to the left in the same direction as the front wheel, which can reduce the body roll during lane changes or turns and enhance the stability of the vehicle. In one embodiment, the rear wheel 41 steering function can improve the steering speed and stability of the vehicle, and can also improve the stability of the vehicle's driving, and has low power consumption and a long service life.

[0059] Figure 2 Schematic diagram of distributed rear-wheel drive provided in an embodiment of the present application.

[0060] See Figure 1 and Figure 2 As shown, the present application provides a vehicle with a distributed rear-wheel steering device 100 , and the vehicle includes two rear wheels 41 and at least two rear-wheel steering devices 100 .

[0061] The vehicle includes a frame 20, which can serve as the structural framework of the vehicle. The frame 20 can be used to support two rear wheels 41 and can fix two rear wheel steering gears 100. The two rear wheels 41 are located on the left and right sides of the frame 20. The left and right sides of the frame 20 each have at least one rear wheel 41, forming at least one left rear wheel 41 and at least one right rear wheel 41 of the vehicle. In one embodiment, the number of left rear wheels 41 and right rear wheels 41 can be two or more to accommodate vehicles with heavier weights. In one embodiment, the various embodiments of the present application are described using one left rear wheel 41 and one right rear wheel 41 as an example.

[0062] In one embodiment, the frame 20 and the two rear wheels 41 are connected via an axle and a suspension. The frame 20 serves as the vehicle's loading base, connecting the various components of the vehicle into a whole and bearing the loads inside and outside the vehicle. The axle is a component that connects the left and right wheels 40 and is connected to the frame 20 via a suspension. The wheels 40 are mounted at both ends of the axle. The axle transmits the forces acting in all directions between the frame 20 and the wheels 40, as well as the bending moments and torques generated therefrom. The suspension is a general term for all force-transmitting connection devices between the frame 20 and the axle, and is typically composed of elastic elements, guide mechanisms, and shock absorbers. Its function is to transmit the forces and torques acting between the wheels 40 and the frame 20, and to cushion the impact forces transmitted to the frame 20 or the vehicle body from uneven road surfaces, and to attenuate the vibrations caused thereby, thereby ensuring smooth vehicle travel. The wheel 40 includes a hub and a tire. The hub serves as a rigid body for connection and support. The outer ring of the hub surrounds the tire. The wheel 40 can support the weight of the car and alleviate the impact and vibration caused by uneven roads, and generate driving force and braking force through the adhesion between the tire and the road.

[0063] In one embodiment, two rear-wheel steering gears 100 are fixed to the vehicle frame 20 and arranged between the two rear wheels 41. Each of the two rear-wheel steering gears 100 is used to drive one of the two rear wheels 41 to steer. The vehicle frame 20 is used to fix the housings of the two rear-wheel steering gears 100 to secure the rear-wheel steering gears 100. When in operation, the rear-wheel steering gears 100 can apply force to the rear wheels 41 to drive the rear wheels 41 to steer relative to the vehicle frame 20, thereby assisting the vehicle in turning left and rearward. Among them, two rear wheel steering gears 100 are arranged between the left rear wheel 41 and the right rear wheel 41, one rear wheel steering gear 100 is used to drive the left rear wheel 41 to steer, and the other rear wheel steering gear 100 is used to drive the right rear wheel 41 to steer. The two rear wheel steering gears 100 respectively control the steering of the left rear wheel 41 and the right rear wheel 41, realizing the steering decoupling of the left rear wheel 41 and the right rear wheel 41, forming the left rear wheel 41 turning left - the right rear wheel 41 turning left, the left rear wheel 41 turning left - the right rear wheel 41 turning left, and the left rear wheel 41 turning right. There are at least nine coordination ways of steering the left and right rear wheels 41, including left rear wheel 41 turns left - right rear wheel 41 does not turn, left rear wheel 41 turns left - right rear wheel 41 turns right, left rear wheel 41 does not turn - right rear wheel 41 turns left, left rear wheel 41 does not turn - right rear wheel 41 does not turn, left rear wheel 41 does not turn - right rear wheel 41 turns right, left rear wheel 41 turns right - right rear wheel 41 turns left, left rear wheel 41 turns right - right rear wheel 41 does not turn, and left rear wheel 41 turns right - right rear wheel 41 turns right.

[0064] The vehicle provided in this embodiment is suitable for a distributed rear wheel 41 steering system structure of a rear wheel 41 steering system of an electric vehicle system. Under the distributed rear wheel 41 steering system structure, the left and right rear wheels 41 of the electric vehicle can be steered independently. This unique design enables the vehicle's control flexibility under various driving conditions to reach a new level.

[0065] Figure 3 This is a schematic diagram of the rear wheels turning inward in an embodiment of the present application. Figure 4 A schematic diagram of the rear wheels turning outward in a toe-shaped manner provided in an embodiment of the present application.

[0066] See Figure 3 and Figure 4As shown, in one embodiment, the vehicle provided by the embodiment of the present application can realize the inward and outward eight-shaped steering of the left and right rear wheels 41. For example, the distributed rear-wheel steering system structure can enable the rear wheels 41 to realize inward eight-shaped steering, that is, the left rear wheel 41 turns right and the right rear wheel 41 turns left; or realize outward eight-shaped steering, that is, the left rear wheel 41 turns left and the right rear wheel 41 turns right. When the vehicle is traveling at a low speed and needs to turn at a large angle, such as making a U-turn in a narrow parking lot, the system can control the left rear wheel 41 to turn right by a certain angle and the right rear wheel 41 to turn left by a certain angle, forming a steering posture similar to an inward eight-shaped steering. At this time, the turning radius of the vehicle is greatly reduced, and it can easily complete the steering action that was difficult to achieve with the traditional steering system in the past, greatly improving the vehicle's handling performance in complex and narrow environments, and bringing a more convenient driving experience to users.

[0067] In one embodiment, the vehicle provided by the embodiment of the present application can improve the stability of the vehicle when a single wheel has a flat tire. The core advantage of the distributed rear wheel 41 steering drive structure lies in its high degree of independence. The steering execution unit of each rear wheel 41 is an independent individual. When a single rear wheel 41 has a flat tire, the central control system of the vehicle will immediately detect the abnormality of the flat tire rear wheel 41 and quickly adjust the control strategy. By precisely controlling the steering angle of the other rear wheel 41, combined with other dynamic parameters of the vehicle, such as vehicle speed and center of gravity position, the vehicle is guided to decelerate smoothly, and skidding and rollover are prevented as much as possible, ultimately achieving controlled parking. The ability to ensure basic driving safety of the vehicle even in the event of steering failure of some wheels 40 greatly improves the reliability and safety of the vehicle, and provides users with solid protection in complex and changing traffic environments.

[0068] Figure 5 A schematic diagram of the steering structure provided in an embodiment of the present application, Figure 6 A schematic cross-sectional view of a steering gear provided in an embodiment of the present application.

[0069] In one embodiment, the rear wheel steering gear includes a steering motor, a transmission mechanism and a screw. The steering motor is used to drive the screw of the screw to move axially through the transmission mechanism. One end of the screw is used to drive the rear wheel on one side of the vehicle to steer through the steering tie rod, and the other end of the screw is used to receive the drive of the transmission mechanism through the nut of the screw.

[0070] In one embodiment, see Figure 5 and Figure 6As shown, the rear wheel steering gear 100 includes a steering motor 110, a transmission mechanism 170, and a screw 130. The screw 130 includes a nut 131 and a screw 132. The nut 131 includes a threaded hole, the internal threads of which mate with the external threads of the screw 132. Since the screw 132 is restricted from rotating, the nut 131 can drive the screw 132 to move axially when it rotates. The axial movement of the screw 132 can drive the rear wheel 41 to steer via the steering tie rod 140. In one embodiment, the axial direction of the screw 132 is the central axis of the screw 132. The central axis coincides with the extension direction of the screw 132, and the central axis of the screw 132 passes through the center of the cross section of the screw 132. In one embodiment, the center of the nut 131 is the center of the cross section of the threaded hole of the nut 131. The nut 131 can rotate about the central axis of the nut 131, and the central axis passing through the center of the nut 131 coincides with the central axis of the screw 132.

[0071] The steering motor 110 includes a stator 111 and a motor shaft 112. When energized, the stator 111 generates magnetic force to rotate the motor shaft 112. Rotation of the motor shaft 112 drives the transmission mechanism 170, which in turn rotates the nut 131 of the lead screw 130. Rotation of the nut 131 drives the axial movement of the screw 132, which in turn drives the rear wheels 41 to steer via the tie rods 140.

[0072] In one embodiment, the steering motor 110 is located on one radial side of the screw rod 130 along the radial direction of the screw rod 132. The radial direction of the screw rod 132 is perpendicular to the central axis of the screw rod 132.

[0073] In one embodiment, the transmission mechanism 170 is connected between the steering motor 110 and the nut 131 of the lead screw 130. The rotation axis of the motor shaft 112 of the steering motor 110 and the rotation axis of the nut 131 do not coincide. The rotation of the motor shaft 112 is transmitted to the rotation of the nut 131 on a different axis via the transmission mechanism 170. In one embodiment, the steering tie rod 140 and the nut 131 are connected to the axial ends of the screw 132. The steering tie rod 140 is connected to one end of the screw 132, and the one end of the screw 132 is used to drive the rear wheel 41 of one side of the vehicle to steer through the steering tie rod 140. The other end of the screw 132 is connected to the transmission mechanism 170 via the nut 131, and the other end of the screw 132 is used to receive the drive of the transmission mechanism 170 through the nut 131 of the lead screw 130. The motor shaft 112 drives the nut 131 to rotate through the transmission mechanism 170, which can fully utilize the entire axial screw 132 and reduce the axial length of the screw 132, thereby reducing the axial length of the rear wheel steering gear 100 and reducing the axial space of the rear wheel steering gear 100 in the vehicle.

[0074] In one embodiment, the central axis 112a of the motor shaft 112 of the steering motor 110 is arranged parallel to the central axis 132a of the screw 132, and the distance between the central axis 112a of the motor shaft 112 and the central axis 132a of the screw 132 along the arrangement direction of the screw 132 and the steering motor 110 is greater than the outer ring radius R1 of the stator 111 of the steering motor 110.

[0075] In one embodiment, the central axis 112a of the motor shaft 112 is parallel to the central axis 132a of the screw 132. It should be noted that during actual design, processing, and assembly, the central axis 112a of the motor shaft 112 and the central axis 132a of the screw 132 may have an error of, for example, within 30 degrees. In order to reduce the radial dimension of the rear wheel steering gear 100 along the screw 132, the motor shaft 112 drives the nut 131 of the lead screw 130 on one radial side to rotate through a separate transmission mechanism 170, which also falls within the definition of the central axis 112a of the motor shaft 112 and the central axis 132a of the screw 132 being parallel as defined in this application.

[0076] In one embodiment, along the arrangement direction of the screw 132 and the steering motor 110, that is, along the direction perpendicular to the central axis 112a of the screw 132 toward the central axis 112a of the motor shaft 112, the distance L1 between the central axis 112a of the motor shaft 112 and the central axis 132a of the screw 132 is greater than the outer radius R1 of the stator 111 of the steering motor 110. In one embodiment, the stator 111 is an annular structure wound with a coil. The outer diameter of the stator 111 is close to the maximum outer diameter of the steering motor 110. Generally, the difference between the outer diameter of the stator 111 and the maximum outer diameter of the steering motor 110 is equal to the thickness of the housing of the steering motor 110. The maximum outer diameter of the steering motor 110 is directly related to the outer diameter of the stator 111.

[0077] In one embodiment, the distance between the central axis 112a of the motor shaft 112 and the central axis 132a of the screw 132 along the arrangement direction of the screw 132 and the steering motor 110 is greater than the sum of the outer ring radius R1 of the stator 111 of the steering motor 110 and the radius R2 of the screw 132. The radius of the screw 132 refers to the distance between the center of the cross section and the outermost edge of the cross section along a cross section perpendicular to the central axis of the screw 132. In one embodiment, the outer peripheral surface of the screw 132 is provided with an external thread, and the radius of the screw 132 is the vertical distance between the outermost end of the external thread and the central axis 132a of the screw 132.

[0078] The present application provides a distributed rear-wheel steering gear for driving the two rear wheels of a vehicle to steer separately, forming a distributed rear-wheel steering gear, realizing steering decoupling of the two rear wheels, and realizing steering modes such as outward-facing or inward-facing steering in response to different driving environments of the vehicle, enabling the vehicle to make better steering choices to match the current environment; and; the steering motor and the lead screw of the rear-wheel steering gear are arranged along the radial direction of the lead screw. When two rear-wheel steering gears are installed on the frame of the vehicle to drive the two rear wheels separately, the lateral space occupied by the rear-wheel steering gear in the vehicle can be reduced, the structure is compact, and installation space is saved; the two rear-wheel steering gears can be arranged at intervals along the line connecting the two rear wheels, thereby improving the force balance of the frame after the rear-wheel steering gear is installed in the vehicle, and also improving the symmetry of the installation of various components in the vehicle. The axis of the steering motor is parallel to the axis of the screw of the lead screw. The steering motor and the lead screw can be driven by a transmission mechanism, allowing the steering motor to extend in a direction parallel to the screw. This prevents the rear-wheel steering gear from occupying too much space in a direction perpendicular to the axis of the lead screw, thereby forming an irregular shape. This facilitates spatial coordination between the rear-wheel steering gear and other structures after installation within the vehicle. Furthermore, the radial spacing between the central axis of the motor shaft and the central axis of the screw is greater than the radius of the outer ring of the steering motor's stator, ensuring that no installation interference occurs between the steering motor and the screw. The rotation of the motor shaft drives the screw nut to rotate via the transmission mechanism, and the rotation of the nut drives the axial displacement of the screw to drive rear-wheel steering.

[0079] Figure 7 This is a schematic diagram of the connection between the steering motor, locking mechanism, transmission mechanism and screw in the embodiment of the present application. Figure 8 This is an exploded schematic diagram of the nut and transmission wheel provided in the embodiment of the present application.

[0080] In some possible embodiments, see Figure 6 、 Figure 7 and Figure 8 As shown, the transmission mechanism 170 includes two transmission wheels 171 and a belt 172. The belt 172 is looped around the two transmission wheels 171. The motor shaft 112 of the steering motor 110 is used to drive one of the two transmission wheels 171a to rotate. One transmission wheel 171a is used to drive the other transmission wheel 171b of the two transmission wheels 171 to rotate through the belt 172, and the other transmission wheel 171b is used to drive the nut 131 to rotate.

[0081] In one embodiment, a transmission wheel 171a is coaxially fixed to the motor shaft 112, and the central axis of the transmission wheel 171a coincides with the central axis of the motor shaft 112. The transmission wheel 171a and the motor shaft 112 can rotate about the same rotation axis, and the motor shaft 112 can drive the transmission wheel 171a to rotate. In one embodiment, the transmission wheel 171a and the motor shaft 112 can be an integral structure, such as a transmission wheel 171a that is annularly mounted and fixed to the motor shaft 112 to form an integral structure, or the motor shaft 112 has a gear or other structure on its outer circumference that can cooperate with a belt, so that the motor shaft 112 and the transmission wheel 171a are integrally injection molded.

[0082] In one embodiment, the other transmission wheel 171b and the nut 131 of the screw 130 are coaxially fixed, the central axis of the other transmission wheel 171b coincides with the central axis of the nut 131, and the other transmission wheel 171b and the screw 132 can rotate around the same rotation axis.

[0083] One transmission wheel 171a and the other transmission wheel 171b can be arranged opposite each other along the radial direction of the screw rod 132, with the projection of one transmission wheel 171a along the radial direction of the screw rod 132 at least partially overlapping with the projection of the other transmission wheel 171b. A belt 172 is looped around one transmission wheel 171a and the other transmission wheel 171b, and the belt 172 can be tightly attached to the outer circumferences of the one transmission wheel 171a and the other transmission wheel 171b via a tensioning pulley 171c located outside the belt 172. The tensioning pulley 171c can move radially along the one transmission wheel 171a to move closer to or further away from the belt, thereby adjusting the tightness of the belt 172 and ensuring that the belt 172 can smoothly and safely transmit the rotation of the one transmission wheel 171a and the other transmission wheel 171b.

[0084] In one embodiment, the motor shaft 112 of the steering motor 110 drives a transmission wheel 171a fixed thereto to rotate, and the transmission wheel 171a drives another transmission wheel 171b on the radial side to rotate through a belt 172. The rotation directions of the transmission wheel 171a and the other transmission wheel 171b are the same. When the other transmission wheel 171b rotates, it drives the nut 131 to rotate. The nut 131 rotates to drive the screw 132 to move axially, and the screw 132 moves axially to pull the rear wheel 41 of the vehicle to steer.

[0085] In some possible embodiments, see Figure 6 、 Figure 7 and Figure 8As shown, the rear-wheel steering gear 100 includes a bearing 133, the inner race of which is fixedly connected to a nut 131. In one embodiment, the inner race 1331 of the bearing 133 is encircled and fixed to the outer circumference of the nut 131. The outer race 1332 of the bearing 133 is used to fix the housing 150 of the rear-wheel steering gear 100. Along the axial direction of the screw 132, the bearing 133 is coaxial with and spaced apart from another transmission wheel 171b. Along the direction from the motor shaft 112 toward the screw 132, the projection of the motor shaft 112 and the bearing 133 at least partially overlap.

[0086] In one embodiment, the bearing 133 includes an inner ring 1331 and an outer ring 1332, the central axis of the inner ring 1331 coincides with the central axis of the outer ring 1332, the outer ring 1332 is sleeved on the circumferential outside of the inner ring 1331, a plurality of balls are arranged between the outer ring 1332 and the inner ring 1331, and the plurality of balls are spaced between the inner ring 1331 and the outer ring 1332 to reduce the friction of relative rotation between the inner ring 1331 and the outer ring 1332.

[0087] In one embodiment, the housing 150 of the rear wheel steering gear 100 includes a bearing groove 154, which can be located on the inner wall of the housing 150 for accommodating the screw 130. The outer ring 1332 can be accommodated and fixed in the bearing groove 154, for example, by a fixed connection with screws.

[0088] In one embodiment, the inner ring 1331 is sleeved on a portion of the outer circumference of the nut 131 and is fixedly connected to the nut 131. When the nut 131 rotates, it can drive the inner ring 1331 to rotate. The bearing 133 can support the nut 131 and the housing 150 in the radial direction of the nut 131, so that the rotation axis of the nut 131 will not be offset during rotation, thereby preventing the nut 131 from running off course during rotation.

[0089] In one embodiment, along the axial direction of the nut 131, the bearing 133 and the other transmission wheel 171b are spaced apart, and the central axis of the bearing 133 coincides with the central axis of the other transmission wheel 171b, and the other transmission wheel 171b, the nut 131, the screw 132 and the inner ring 1331 all rotate along the same axis.

[0090] In one embodiment, along the axial direction of the screw 132, the bearing 133 faces the other transmission wheel 171b, which is consistent with the direction of the motor shaft 112 toward the one transmission wheel 171a. The outer diameter of the motor shaft 112 of the steering motor 110 is smaller than the outer diameter of the stator 111 of the steering motor 110. In embodiments where the motor shaft 112 is connected to the transmission mechanism 170 via the locking mechanism 120, the outer diameter of the locking mechanism 120 is also smaller than the outer diameter of the stator 111, thereby forming an annular concave structure between the transmission mechanism 170 and the stator 111.

[0091] The outer diameter of the other transmission wheel 171 b is smaller than the outer diameter of the bearing 133 , and the outer diameter of the bearing 133 is larger than the outer diameter of the screw 132 , so that the bearing 133 forms an annular protrusion structure on one side of the other transmission wheel 171 b .

[0092] In this embodiment, the bearing 133 and the motor shaft 112 are arranged on the same axial side of the transmission mechanism 170, and the projection of the motor shaft 112 and the bearing 133 along the direction of the motor shaft 112 toward the screw 132 at least partially overlap. The concave structure formed by the motor shaft 112 between the transmission mechanism 170 and the stator 111 is used to accommodate the protruding bearing 133, which can reasonably utilize the various spaces of the rear wheel steering gear, reduce the size of the rear wheel steering gear in the direction of the motor shaft 112 toward the screw 132, and reduce the space occupied by the rear wheel steering gear in the vehicle.

[0093] In one embodiment, the steering motor 110 is connected to the transmission mechanism 170 via a locking mechanism 120. One end of the locking mechanism 120 is connected to the motor shaft 112, and the other end is connected to the transmission mechanism 170. The outer diameter of the locking mechanism 120 is smaller than the outer diameter of the stator 111, and the locking mechanism 120 also forms an annular concave structure between the transmission mechanism 170 and the stator 111. In this embodiment, along the direction of the motor shaft 112 toward the screw 132, the projection of at least one of the motor shaft 112 and the locking mechanism 120 and the bearing 133 at least partially overlap. The concave structure between the transmission mechanism 170 and the stator 111 can accommodate the protruding bearing, which can reasonably utilize the various spaces of the rear wheel steering gear, reduce the size of the rear wheel steering gear in the direction of the motor shaft 112 toward the screw 132, and reduce the space occupied by the rear wheel steering gear in the vehicle.

[0094] In one embodiment, the steering motor 110 and the bearing 133 are both located along the axial direction of the screw 132 on the side of the transmission mechanism 170 toward the rear wheel 41 driven by it, so that the rear wheel steering gear 100 can achieve structural and external matching of each component in both the axial and radial directions, thereby reducing the axial and radial dimensions.

[0095] This application transmits the rotation of the steering motor to the nut of the screw through a belt, and the motor shaft drives the nut to rotate through the belt transmission to drive the two rear wheels to steer. The transmission is stable, the noise generated during transmission is small, and the structural setting is simple. The axial and radial volume occupied is small, which can match the radial spacing between the steering motor and the screw, reducing the space occupied by the rear wheel steering gear in the vehicle.

[0096] In some possible embodiments, see Figure 8 As shown, another transmission wheel ring is sleeved on the outer circumference of the nut, the inner diameter of the other transmission wheel is equal to the outer diameter of the outer circumference, and the inner threads of the other transmission wheel and the nut are used to be spaced apart along the radial direction of the nut.

[0097] In one embodiment, another transmission wheel 171b is sleeved on the outer peripheral surface of the nut 131. The outer peripheral surface of the nut 131 can be a smooth arc surface, and the inner diameter of the through-hole of the other transmission wheel 171b is equal to the outer diameter of the outer peripheral surface of the nut 131. The other transmission wheel 171b can be interference fit with the nut 131 to achieve a fixed connection between the other transmission wheel 171b and the nut 131. In one embodiment, the outer peripheral surface of the nut 131 can be provided with some raised structures, such as axially extending convex strips or axially extending waves. The through-hole of the other transmission wheel 171b cooperates with the outer peripheral surface of the nut 131 to limit the circumferential relative movement between the other transmission wheel 171b and the nut 131, and the other transmission wheel 171b can drive the nut 131 to rotate.

[0098] In one embodiment, an annular groove can be provided on the outer peripheral surface of the nut 131, and a portion of the other transmission wheel 171b can be accommodated in the annular groove. The inner walls on both sides of the annular groove along the axial direction of the nut 131 abut against a portion of the outer wall of the other transmission wheel 171b. The annular groove can limit the relative movement between the other transmission wheel 171b and the nut 131 along the axial direction of the nut 131, thereby ensuring the safety and stability of the other transmission wheel 171b driving the nut 131 to rotate.

[0099] In one embodiment, the other transmission wheel 171b and the nut 131 can be an integral structure, such as the other transmission wheel 171b is looped and fixed on the nut 131 to form an integral structure; or the nut 131 forms a gear or other structure on the outer peripheral surface that can cooperate with the belt 172, so that the nut 131 and the other transmission wheel 171b are injection molded as a whole.

[0100] Slipping the other transmission wheel ring onto the outer circumference of the nut increases the connection area between the other transmission wheel and the nut, maintains a force balance between the transmission wheel and the nut at the contact surface, and ensures the stability of the other transmission wheel in driving the nut's rotation. Furthermore, since the nut requires a certain axial length to accommodate the screw for transmission, slipping the other transmission wheel ring onto the outer circumference of the nut utilizes the axial space within the nut without further increasing the combined axial length of the nut and the other transmission wheel, thereby reducing the axial length of the rear wheel steering gear.

[0101] In some possible embodiments, see Figure 6 and Figure 7 As shown, the screw 130 includes a ball screw, and the motor shaft 112 drives the nut 131 to rotate through the belt 172 and two transmission wheels 171. The nut 131 is used to drive the screw 132 to move axially, and the screw 132 is used to drive the rear wheels 41 of the vehicle to steer through the steering tie rod 140.

[0102] In one embodiment, balls are filled between the nut 131 and the screw 132 of the ball screw. When the nut 131 and the screw 132 rotate relative to each other, the balls roll between the nut 131 and the screw 132 to improve the lubrication between the nut 131 and the screw 132, reduce friction loss, and the ball screw has high transmission efficiency.

[0103] The motor shaft 112 drives the nut 131 to rotate through the belt 172 and two transmission wheels 171, and the other transmission wheel 171b is coaxially fixed to the nut 131 of the ball screw. The motor shaft 112 drives one transmission wheel 171a to rotate, and one transmission wheel 171a drives the other transmission wheel 171b to rotate through the belt 172, and the other transmission wheel 171b drives the nut of the ball screw to rotate. The nut of the ball screw is used to accurately convert the rotation of the steering motor 110 into the linear motion of the screw, thereby driving a rear wheel steering to achieve precise adjustment of the rear wheel steering angle; and the ball screw can efficiently convert the torque output by the steering motor into linear thrust and transmit it to the steering tie rod 140, ensuring that the rear wheel 41 can quickly respond to steering commands, especially in situations where the vehicle's driving direction needs to be changed quickly, such as emergency avoidance, to ensure sufficient steering force output and complete the steering action in time, playing a greater role in the distributed rear wheel steering mechanism.

[0104] Figure 9 This is a schematic structural diagram of the trapezoidal lead screw in an embodiment of the present application.

[0105] In some possible embodiments, see Figure 7 、 Figure 8 and Figure 9 As shown, the screw 130 includes a trapezoidal screw, and the motor shaft drives the nut 131 of the screw 130 to rotate through a belt 172 and two transmission wheels 171. The nut 131 is used to drive the screw 132 to move axially, and the screw 132 is used to drive the rear wheels 41 of the vehicle to steer through the steering tie rod 140.

[0106] In one embodiment, the nut 131 and the screw 132 of the trapezoidal screw are directly engaged by threads, without complex structures such as complex balls and circulation devices. The manufacturing process is relatively easy, the production cost is low, and it is also easy to install and maintain. In addition, the lead angle of the screw of the trapezoidal screw can be designed so that the trapezoidal screw can be designed to meet the load-bearing capacity and self-locking requirements required in the current rear wheel steering gear. In one embodiment, the lead angle of the screw refers to the angle between the helix of the external thread of the screw and the axis.

[0107] In one embodiment, the motor shaft 112 drives the nut 131 to rotate through a belt 172 and two transmission wheels 171, and another transmission wheel 171b is coaxially fixed to the nut 131 of the trapezoidal screw. The motor shaft 112 drives one transmission wheel 171a to rotate, and one transmission wheel 171a drives another transmission wheel 171b to rotate through a belt 172, and the other transmission wheel 171b drives the nut of the trapezoidal screw to rotate. The nut of the trapezoidal screw is used to accurately convert the rotation of the steering motor 110 into the linear motion of the screw, thereby driving a rear wheel steering and realizing precise adjustment of the rear wheel steering angle.

[0108] In some possible embodiments, the lead angle of the thread of the screw 132 of the trapezoidal screw is less than or equal to 4.5 degrees, and the trapezoidal screw has a locking function: when the vehicle is parked, the locking mechanism of the trapezoidal screw is locked to prevent accidental steering of the rear wheels, providing additional parking protection. When the steering of a single rear wheel fails, the locking mechanism of the trapezoidal screw is locked and the screw is locked in the current position, which helps to maintain the stability of the direction of the rear wheel and prevent deviation from affecting the driving safety of the vehicle. In one embodiment, when the lead angle of the thread is less than or equal to the equivalent friction angle, for example, when the lead angle of the trapezoidal screw thread is 4 degrees, the locking mechanism of the trapezoidal screw can achieve self-locking to prevent the rear wheel 41 from accidentally steering under the action of external force when the steering motor stops rotating.

[0109] In some possible embodiments, see Figure 5 、 Figure 6 and Figure 7 As shown, the rear wheel steering gear 100 includes a steering motor 110, a locking mechanism 120 and a screw 130. Along the arrangement direction of the rear wheel steering gear 100 and the rear wheel 41 correspondingly connected thereto, the steering motor 110, the locking mechanism 120, the screw 130 and the rear wheel 41 are arranged in sequence. The steering motor 110 drives the rear wheel 41 to steer through the screw 130. The steering motor 110 also limits the vibration of the screw 130 relative to the frame 20 through the locking mechanism 120.

[0110] In one embodiment, each rear-wheel steering system 100 provided herein includes a steering motor 110, a locking mechanism 120, and a lead screw 130. The steering motor 110 is configured to convert electrical energy transmitted from the power battery 30 into mechanical energy to cause the motor shaft of the steering motor to rotate. The motor shaft of the steering motor is connected to the lead screw 130 via the locking mechanism 120. The locking mechanism 120 drives the lead screw 130 to rotate, which then converts the rotation into linear motion along the axial direction to drive the rear wheels 41 to steer.

[0111] In one embodiment, the steering motor 110 is fixed to the vehicle frame 20, and the motor shaft of the steering motor 110 is parallel to the axial direction of the rear wheel 41. The lead screw 130 is slidably connected to the vehicle frame 20 along an axial direction parallel to the rear wheel 41. The lead screw 130 extends along an axial direction parallel to the rear wheel 41, and at least one axial end of the lead screw 130 is connected to one rear wheel 41 via a steering tie rod 140. In one embodiment, the steering motor 110 and the lead screw 130 are both fixed within a housing 150 of the rear wheel steering gear 100 of the wheel 40, and are fixed to the vehicle frame 20 through the housing 150.

[0112] In one embodiment, one axial end of the lead screw 130 is connected to a rear wheel 41 via a tie rod 140. Driven by the steering motor 110, the lead screw 130 is displaced axially, thereby driving the tie rod 140 to displace axially along the lead screw 130. The tie rod 140 can rotate relative to the wheel 40 along the axis of its rotating shaft structure, thereby steering the wheel 40 by pushing or pulling it. In one embodiment, of the two rear wheel steering gears 100, one rear wheel steering gear 100 steers the left wheel 40 via the tie rod 140 disposed therein, and the other rear wheel steering gear 100 steers the right wheel 40 via the tie rod 140 disposed therein.

[0113] In one embodiment, the locking mechanism 120 is used to transmit and connect the steering motor 110 and the lead screw 130. The steering motor 110 also limits the jumping of the lead screw 130 relative to the frame 20 through the locking mechanism 120. The locking mechanism 120 can lock the rear wheel 41, so that the steering motor 110 compensates for the locking torque, prevents the rear wheel 41 from turning unexpectedly, and ensures the steering reliability of the entire vehicle. In one embodiment, the locking mechanism 120 is used to transmit and connect the motor shaft of the steering motor 110 and the lead screw 130. During the rotation of the steering motor 110, the locking mechanism of the locking mechanism 120 is opened to drive the lead screw 130 to move axially, thereby driving the rear wheel 41 to turn. Before the steering motor 110 rotates, the locking mechanism of the locking mechanism 120 is closed, locking and limiting the sudden displacement of the lead screw 130 along its own axis, thereby limiting the axial movement of the lead screw 130 relative to the vehicle frame, so that the lead screw 130 can only move axially under the drive of the steering motor 110, limiting the axial displacement of the lead screw 130 caused by the external force acting on the rear wheels, thereby protecting the rear wheels from uncontrollable steering and protecting the safe operation of the vehicle. The steering motor 110 is used to drive the lead screw nut through the locking mechanism 120 to achieve steering of at least two rear wheels 41 of the vehicle. The vehicle controller is used to output a first control signal to instruct the steering motor 110 to rotate to limit the rotation angle of the locking mechanism 120 to less than a preset angle; the first control signal is used to indicate that the reaction force of the at least two rear wheels 41 on the locking mechanism 120 exceeds the locking force of the locking mechanism 120 on the lead screw 130.

[0114] For details, please refer to Figure 7 、 Figure 11 and Figure 12 As shown, Figure 11 This is a schematic diagram of the exploded structure of the locking mechanism provided in the embodiment of the present application. Figure 12 Schematic diagram of the assembly structure of the locking mechanism provided in the embodiment of the present application.

[0115] like Figure 11 and Figure 12 As shown, the locking mechanism includes a movable part and an output shaft, the output shaft is used to transmit and connect the motor shaft and the transmission mechanism, and the movable part is used to move closer to or farther away from the output shaft to lock or release the output shaft from rotating.

[0116] In one embodiment, the locking mechanism 120 includes a drive shaft 121, a movable member 122, an output shaft 123, and a housing 124. The axis of the drive shaft 121 is parallel to the axis of the lead screw 130. The movable member 122 is used to connect to the motor shaft of the steering motor 110 through the drive shaft 121. The housing 124 is annular, and the movable member 122 is sleeved within the housing. The output shaft 123 is located on the side of the movable member 122 facing away from the steering motor 110. The axis of the output shaft 123 is parallel to the axis of a transmission wheel of the transmission mechanism. The movable member 122 can move radially toward or away from the output shaft 123 to lock or release the output shaft 123. During rotation of the motor shaft of the steering motor, the drive shaft 121, driven by the motor shaft, drives the movable member 122 radially toward and abuts the output shaft 123, thereby rotating the output shaft 123 and, in turn, the nut of the lead screw 130. Before the steering motor 110 rotates, the movable member 122 moves away from the output shaft 123 in the radial direction of the output shaft 123 to release the output shaft 123 and restrict the rotation of the output shaft 123 , thereby restricting the axial displacement of the lead screw.

[0117] In the embodiment of the present application, a distributed rear wheel 41 drive is designed, with two rear wheel steering gears 100 controlling the two rear wheels 41, respectively. Each rear wheel steering gear 100 is independently provided with a corresponding locking mechanism 120. This allows the two rear wheel steering gears 100 to drive and lock the steering angles of the two rear wheels 41, respectively, under the distributed drive design. This decouples the steering of the left and right rear wheels 41 while also controlling the steering angles of both wheels 40, preventing a single rear wheel 41 from accidentally turning too far and thus reducing vehicle stability. Therefore, locking mechanisms 120 are provided for both rear wheels 41 to provide protection. Furthermore, having different locking mechanisms 120 for each rear wheel 41 also facilitates coordination between the two. The controller can coordinate the rotation angles of the two locking mechanisms 120, in conjunction with corresponding control methods, to prevent excessive steering angle deviations of the two rear wheels 41, impacting driving safety and the life of the vehicle structure.

[0118] In one embodiment, the lead screw 130 is a trapezoidal lead screw, and the steering motor 110 is connected to the transmission mechanism 170 through the locking mechanism 120. The trapezoidal lead screw and the locking mechanism 120 cooperate to form a double locking structure, providing double protection for the steering accuracy of the two rear wheels of the vehicle.

[0119] Figure 10 Schematic diagram of the structure of the planetary roller screw in the embodiment of the present application.

[0120] In some possible embodiments, see Figure 7 、 Figure 8 and Figure 10 As shown, the screw 130 includes a planetary roller screw, and the motor shaft 112 drives the nut 131 of the screw 130 to rotate through the belt 172 and two transmission wheels 171. The nut 131 is used to drive the screw 132 to move axially, and the screw 132 is used to drive the rear wheels 41 of the vehicle to steer through the steering tie rod 140.

[0121] In one embodiment, rollers are filled between the nut 131 and the screw 132 of the planetary roller screw, and the central axis of the roller is parallel to the central axis of the screw 132. The outer peripheral surface of the roller includes an external thread, and the external thread of the outer peripheral surface of the roller cooperates with the internal thread of the nut and the external thread of the screw 132 respectively. The roller can be supported between the nut 131 and the screw 132. When the nut 131 rotates, it can drive the roller to rotate. The roller transmits the rotation of the nut 131 to the inner screw 132 to drive the screw 132 to rotate. Since the nut 131 is axially fixed to the housing 150 of the rear wheel steering gear, the nut 131 is axially stationary relative to the housing 150. When the screw 132 rotates, it will move axially relative to the housing 150 to pull the rear wheel 41 to steer through the steering tie rod 140.

[0122] In one embodiment, the lead angle of the screw thread of the planetary roller screw is less than 7 degrees. The planetary roller screw used in this embodiment has a screw shaft with a small lead angle, a non-circular arc thread, and can be made of a high-friction material. This facilitates achieving high lead accuracy, enabling precise micro-feeding, and possesses a self-locking function. During long-term use of the vehicle's rear-wheel steering system, the planetary roller screw can consistently maintain high-precision steering control, reducing the problem of reduced steering accuracy due to wear. Furthermore, the planetary roller screw of this embodiment is used in the rear-wheel steering gear, eliminating the need for an external locking mechanism, thereby reducing the axial dimensions of the rear-wheel steering gear.

[0123] In one embodiment, the planetary roller screw includes 8-14 rollers, including 8 and 14. The rollers are located between the nut and the screw along the radial direction of the screw, and the plurality of rollers are used to be spaced apart along the circumference of the screw. Among them, there can be 10 rollers or 12 rollers. The plurality of rollers are evenly distributed between the nut and the screw and spaced apart along the circumference. Any two adjacent rollers are threadedly matched, and each roller is threadedly matched with the nut and the screw to improve the stability and accuracy of the planetary roller screw transmission, prevent the rollers from being misaligned or even deviating during rotation, and improve the stability of the self-locking function.

[0124] In some possible embodiments, the transmission mechanism 170 includes two gears, which are meshed with each other. The screw 130 includes a ball screw 130. One of the two gears is used to be coaxial with the motor shaft 112, and the other gear is used to be coaxial with the nut 131 of the screw 130. The motor shaft 112 drives the driving nut 131 to rotate by driving the meshing transmission of the two gears. The nut 131 is used to drive the screw 132 to move axially, and the screw 132 is used to drive the wheel to steer through the steering tie rod 140.

[0125] In one embodiment, both transmission wheels of the transmission mechanism 170 are gears that mesh with each other. One gear, similar to the transmission wheel 171a, can be coaxial with and fixedly connected to the motor shaft 112. Rotation of the motor shaft 112 drives the coaxial rotation of the one gear, which in turn drives the meshed gear to rotate. The other gear, similar to the transmission wheel 171b, can be coaxial with and fixedly connected to the nut 131. Rotation of the other gear drives the nut 131, thereby driving axial movement of the screw 132 to steer the rear wheel 41.

[0126] In one embodiment, the diameters of the two gears may be different, thereby forming a certain transmission ratio. The transmission ratio of the gear transmission is more precise, and the gear matching structure is more compact, the transmission efficiency is high, and the power and speed range that can be transmitted is larger.

[0127] In one embodiment, regardless of whether the transmission mechanism 170 adopts a belt or gear transmission method, it can be applied to screw structures such as ball screws, trapezoidal screws and planetary roller screws. This embodiment only takes the ball screw as an example, but it is not limited to being applied only to ball screws under gear transmission.

[0128] In one embodiment, the rear wheel steering gear includes a locking mechanism, the steering motor is used to connect one of the gears through the locking mechanism, and the locking mechanism is used to limit the rotation of the two gears when the steering motor stops rotating.

[0129] The locking mechanism 120 is used to transmit and connect the steering motor 110 and the lead screw 130. The locking mechanism 120 transmits and connects the motor shaft 112 and one of the gears. The steering motor 110 limits the rotation of one gear through the locking mechanism 120, thereby limiting the jumping of the lead screw 130 relative to the frame 20. The locking mechanism 120 can lock the rear wheel 41, so that the steering motor 110 compensates for the locking torque, prevents the rear wheel 41 from turning accidentally, and ensures the steering reliability of the entire vehicle. In one embodiment, the locking mechanism 120 is used to transmit and connect the motor shaft of the steering motor 110 and one of the gears. During the rotation of the steering motor 110, the locking mechanism of the locking mechanism 120 is opened to drive the lead screw 130 to move axially, thereby driving the rear wheel 41 to turn. Before the steering motor 110 rotates, the locking mechanism of the locking mechanism 120 is closed. The locking mechanism 120 locks and restricts the rotation of the two gears to limit the sudden displacement of the lead screw 130 along its own axis and to limit the axial jump of the lead screw 130 relative to the vehicle frame. This allows the lead screw 130 to move axially only when driven by the steering motor 110. This limits the axial displacement of the lead screw 130 caused by external forces acting on the rear wheels to protect the rear wheels from uncontrollable steering and to ensure the safe operation of the vehicle. The steering motor 110 is used to drive the lead screw nut through the locking mechanism 120 to achieve steering of at least two rear wheels 41 of the vehicle. The vehicle controller is used to output a first control signal to instruct the steering motor 110 to rotate to limit the rotation angle of the locking mechanism 120 to less than a preset angle. The first control signal is used to indicate that the reaction force of the at least two rear wheels 41 on the locking mechanism 120 exceeds the locking force of the locking mechanism 120 on the lead screw 130.

[0130] It should be noted that the locking mechanism 120 may also include a drive shaft 121, a movable member 122, an output shaft 123, and a housing 124. The axis of the drive shaft 121 is parallel to the axis of the lead screw 130, and the movable member 122 is used to transmit the motor shaft of the steering motor 110 through the drive shaft 121. The housing 124 is annular, and the movable member 122 is sleeved within the housing. The output shaft 123 is located on the side of the movable member 122 facing away from the steering motor 110. The axis of the output shaft 123 is connected in parallel to a transmission gear, thereby achieving transmission gear locking when the steering motor stops operating, thereby locking the rear wheel steering gear.

[0131] By designing a distributed rear-wheel drive, the two rear-wheel steering gears control the two rear wheels respectively, and the two rear-wheel steering gears are independently provided with corresponding locking mechanisms. In this way, under the distributed drive design, the two rear-wheel steering gears drive and lock the steering angles of the two rear wheels respectively, achieving the steering decoupling of the left and right rear wheels while also controlling the steering angles of the two wheels to prevent the accidental steering angle of a single rear wheel from being too large, thereby reducing the stability of the vehicle. Therefore, locking mechanisms are provided for protection of both rear wheels. In addition, the different locking mechanisms corresponding to the two rear wheels also make it easier to achieve coordination between the two. The rotation angles of the two locking mechanisms can be coordinated through the controller to cooperate with the corresponding control method to prevent the steering angles of the two rear wheels from deviating too much, affecting driving safety and the life of the vehicle structure.

[0132] In some possible embodiments, see Figure 17 As shown, the vehicle includes a controller 180, which is used to drive the steering motor 110 of each rear wheel steering gear 100 to rotate independently, and to independently drive the two steering motors 110 to rotate and output torque after the steering of the rear wheels 41 is completed to limit the rotation angle of each locking mechanism 120 to less than a preset angle.

[0133] The rear-wheel steering gear 100 provided in this application includes a controller 180, which is a steering motor controller. The controller 180 is in communication with the steering motor 110. The controller 180 is used to drive the steering motor 110 to rotate and drive the lead screw 130 through the locking mechanism 120 to steer the two rear wheels 41 of the vehicle. In one embodiment, the controller 180 is further used to drive the output torque of the steering motor 110 in response to a control signal to limit the rotation angle of the locking mechanism 120 to less than a preset angle. The control signal is used to indicate that the reaction force of any of the two rear wheels 41 on the locking mechanism 120 exceeds the locking force of the locking mechanism 120 on the lead screw 130.

[0134] In the embodiment of the present application, the controller 180 is used to realize the independent rotation of the two steering motors 110, so that the two rear wheels 41 can be steered independently, forming the vehicle states under different working conditions such as "outward-facing" and "inward-facing", and at the same time, the controller 180 is used to limit the reaction force of the two rear wheels 41 on the locking mechanism 120 to be too large, thereby protecting the rear wheels 41 from uncontrollable jumping relative to the frame 20.

[0135] In one embodiment, see Figure 17 As shown, there are at least two controllers 180 , and the housing 150 of each rear wheel steering gear 100 is used to fix one controller 180 , and each controller 180 is used to drive the steering motor 110 located on the same housing 150 to rotate.

[0136] In one embodiment, two rear wheel steering gears 100 are equipped with two controllers 180 , and each rear wheel steering gear 100 has its corresponding controller 180 , which facilitates structural arrangement and wiring.

[0137] In some possible embodiments, see Figure 17 As shown, each rear wheel steering gear 100 includes a linear displacement sensor 190, which is used to detect the axial displacement of the screw 130. The controller 180 is used to control the rotation angle of the steering motor 110 corresponding to the screw 130 according to the axial displacement.

[0138] In one embodiment, the linear displacement sensor 190 is used to monitor the axial displacement distance of the screw, and determine the steering angle of the rear wheel 41 through precise calculation, and feed the steering angle back to the controller 180. The controller 180 analyzes the steering angle to control the rotation angle and rotation speed of the steering motor 110.

[0139] In one embodiment, the linear displacement sensor is a magnetoelectric displacement sensor, also known as an electromagnetic induction displacement sensor. This sensor uses the distance between the sensor and the screw to cause changes in electromagnetic coupling, thereby inferring the distance the screw 132 has moved relative to the sensor. This magnetoelectric displacement sensor provides a measurement method that does not directly contact the screw 130, resulting in high sensitivity and accuracy. It also prevents the sensor from interfering with the movement of the screw 132. Relying on electromagnetic induction for distance measurement facilitates installation and maintenance.

[0140] Figure 13 This is a schematic diagram of the structure of the rear wheel steering device provided in an embodiment of the present application. Figure 14 This is an exploded schematic diagram of the end cover and the housing provided in the embodiment of the present application. Figure 15 A schematic cross-sectional view of the housing and end cover provided in an embodiment of the present application.

[0141] In one embodiment, see Figure 13 、 Figure 14 and Figure 15 As shown, each rear wheel steering gear 100 includes a shell 150 and an end cover 160, the shell 150 is used to fix the frame 20 and to enclose an accommodating cavity 151 with the end cover 160, the accommodating cavity 151 is used to accommodate the screw 130, and along the axial direction of the screw 130, the end cover 160, the screw 130 and the rear wheel 41 correspondingly connected thereto are arranged in sequence.

[0142] The shell 150 is a hollow structure, and the end cover 160 is located at the end of the shell 150 away from the rear wheel to which it is connected, and is used to enclose an accommodating cavity 151 with the inner wall of the hollow cavity of the shell 150. The accommodating cavity 151 is used to accommodate the screw 130, and the inner wall of the accommodating cavity 151 is used to fix the screw 130.

[0143] In one embodiment, an end cap 160, a screw rod 132 of the screw rod 130, and a rear wheel 41 connected thereto are arranged in sequence along the axial direction of the lead screw 130, with the rear wheel 41 and the end cap 160 located at both axial ends of the screw rod 132. The end cap 160 encloses one end of an accommodating cavity 151 along the axial direction of the screw rod 132. The ends of the two rear wheel steering gears 100 that are close to each other are both enclosed by the end cap 160. The screw rods 132 of the two rear wheel steering gears 100 are isolated by the end cap 160 to prevent interference between the lead screws 130 of the two rear wheel steering gears 100.

[0144] In one embodiment, an accommodating cavity 151 has an opening at one end of the screw 130 axially away from the end cover 160, the screw 130 passes through the opening and is connected to a steering tie rod 140, and is connected to a rear wheel 41 through the steering tie rod 140; or, one end of a steering tie rod 140 passes through the opening into an accommodating cavity 151 and is connected to the screw 132, and the screw 132 is connected to a rear wheel 41 through the steering tie rod 140.

[0145] In one embodiment, see Figure 14 and Figure 15 As shown, the housing 150 is used to enclose another accommodating cavity 152 , and the other accommodating cavity 152 is used to accommodate the locking mechanism 120 . The one accommodating cavity 151 and the other accommodating cavity 152 are used to be arranged at intervals along the radial direction of the screw rod 132 .

[0146] The shell 150 is provided with two accommodating chambers along the radial direction of the screw 132, namely, one accommodating chamber 151 and the other accommodating chamber 152. The one accommodating chamber 151 and the other accommodating chamber 152 are radially separated by a part of the shell 150, so that the screw 132 in one accommodating chamber 151 and the locking mechanism 120 in the other accommodating chamber 152 are separated along the radial direction of the locking mechanism 120.

[0147] Another accommodating cavity 152 extends through the housing 150 along the axial direction of the steering motor 110. The motor shaft of the steering motor 110 can be inserted into the other accommodating cavity 152 to connect with the locking mechanism 120, thereby driving the locking mechanism 120 to rotate. The edge of the other accommodating cavity 152 on the side facing away from the end cover 160 is used to secure the housing of the steering motor 110. A sealing ring can be added between them to seal the locking mechanism 120 within the other accommodating cavity 152.

[0148] In the embodiment of the present application, two rear wheel steering gears 100 are arranged between the two rear wheels 41. The steering motor 110 and the screw 132 of each rear wheel steering gear 100 are arranged radially, which can reduce the axial length of the rear wheel steering gear 100 along the screw 132, so that two rear wheel steering gears 100 can be arranged between the two rear wheels 41, and the two rear wheel steering gears 100 can be arranged along the direction of the line connecting the two rear wheels 41. When the rear wheel steering gear 100 drives the rear wheels 41 to steer, the forces applied to the frame are symmetrical and balanced, thereby preventing asymmetric forces from being formed on the frame and causing deformation of part of the frame structure.

[0149] In one embodiment, the radially arranged locking mechanism 120 and the lead screw 130 can be connected by a transmission mechanism 170. The locking mechanism 120 drives the transmission mechanism 170 to rotate, and the transmission mechanism 170 drives the nut of the lead screw 130 to rotate. In one embodiment, the transmission mechanism 170 includes a structure such as a belt or a gear.

[0150] In one embodiment, see Figure 14 and Figure 15 As shown, along the axial direction of the screw of the lead screw 130, the end cover 160 is used to enclose a connecting cavity 153 with one end of the shell 150, and the end cover 160, the shell 150 and the rear wheel 41 to be connected thereto are arranged in sequence; the connecting cavity 153 is used to connect one accommodating cavity and another accommodating cavity 152 along the radial direction of the screw 132, and to accommodate a belt drive or a gear drive, and the belt drive or the gear drive is used to connect the locking mechanism 120 and the screw 132.

[0151] In one embodiment, end cap 160 is a bowl-shaped structure, including a recess 161. Recess 161 is buckled into one end of housing 150. Along the axial direction of screw 132, end cap 160, housing 150, and rear wheel 41 to which it is connected are arranged in sequence. The inner wall of recess 161 and a portion of the interior of housing 150 enclose a connecting cavity 153. The projection of connecting cavity 153 along the axial direction of screw 132 covers one accommodating cavity 151 and the other accommodating cavity 152, and connecting cavity 153 is used to connect one accommodating cavity 151 with the other accommodating cavity 152.

[0152] The connecting cavity 153 is used to accommodate a transmission mechanism 170, such as a belt drive or gear drive. The transmission mechanism 170 is used to connect the locking mechanism 120 and the nut 131. The steering motor 110 is used to drive the locking mechanism 120 to rotate. When the locking mechanism 120 rotates, the nut 131 on the radial side rotates via the belt or gear. The lead screw 130 converts the rotation into axial displacement to drive the steering of the rear wheel 41.

[0153] In this embodiment, the locking mechanism 120 and the lead screw 130 are relatively fixed within the housing 150 through the cooperation between the end cap 160 and the housing 150, and the housing 150 is sealed from the side of the housing 150 away from the rear wheel to which it is connected. During installation, the end cap 160 and the housing 150 are separated, and the sides of the housing 150 away from the rear wheel to which they are connected are both open. The locking mechanism 120, the lead screw 130, and the transmission mechanism 170 are installed within the housing 150, and the locking mechanism 120, the lead screw 130, and the transmission mechanism 170 are then fixed and sealed by covering the end cap 160.

[0154] Figure 16 For this application Figure 6 A magnified view of a portion of the area.

[0155] In one embodiment, see Figure 6 and Figure 16 Along the axial direction of the screw 132 of the lead screw 130, the end cover 160 includes a groove 161, and there is a gap between the bottom of the groove 161 and the screw 132. The gap distance L2 between the bottom of the groove 161 and the screw 132 is smaller than the depth H1 of the groove.

[0156] The groove 161 is buckled at one end of the housing 150 , and the end cover 160 , the housing 150 and the rear wheel 41 to be connected thereto are arranged in sequence along the axial direction of the screw rod 132 .

[0157] A gap 162 is provided between one end of the screw rod 132 and the bottom wall of the groove 161. The axial length of the gap 162 is less than the depth of the groove 161. One end of the screw rod 132 is inserted deeply into the groove 161, and the end of the screw rod 132 and the bottom wall of the groove 161 are spaced apart and do not contact each other.

[0158] In the embodiment of the present application, a gap is left between the end cover 160 and the screw 132 by design to prevent the screw 132 from rotating and axially displacing and causing structural interference with the end cover 160. In addition, the screw 132 needs to protrude from the transmission mechanism 170 on the side of the transmission mechanism 170 close to the end cover 160 to form a connection with the transmission mechanism 170. The end cover 160 is designed as a groove-shaped structure, and a groove 161 can be formed only at the position for accommodating the screw 132. The outer surface of the end cover 160 is in a protruding shape at the part accommodating the screw 132, and the end cover 160 is in a protruding shape at the part accommodating the locking mechanism 120, so as to release part of the space on the outer surface of the end cover 160. The structural design is more compact, and structural avoidance is made for other structures of the vehicle.

[0159] Figure 18 Schematic diagram of the lead screw and steering yoke.

[0160] In one embodiment, see Figure 18As shown, the vehicle includes a steering yoke 141 , and the planetary roller screw is used to connect the wheel 40 through the steering yoke 141 .

[0161] The present application provides a possible implementation of a vehicle, wherein the vehicle includes the rear wheel steering device provided by any of the above embodiments, and the vehicle includes two rear wheel steering devices 100, both of which are fixed to the vehicle frame, and the two rear wheel steering devices 100 are respectively used to drive one rear wheel 41 of the vehicle to rotate. Figure 3 As shown, the two rear wheel steering gears 100 are respectively used to drive the rear wheels 41 on both sides of the vehicle to steer. The vehicle realizes the outward or inward turning of the two rear wheels 41 through the rear wheel steering gears 100.

[0162] In one embodiment, along the height direction of the vehicle, refer to Figure 1 In the Z direction, the distance between the central axis of the motor shaft 112 and the axis of the rear wheel 41 is equal to the distance between the central axis of the screw 132 and the axis of the rear wheel 41. In the horizontal direction of the vehicle during normal driving, the steering motor 110 of the rear-wheel steering system 100 and the screw 132 of the screw rod 130 are also arranged horizontally, and the axes of the steering motor 110 and the screw 132 are parallel to the line connecting the two rear wheels 41 of the vehicle. This can reduce the height space occupied by the rear-wheel steering system 100 within the vehicle, thereby reducing the height of the vehicle.

[0163] In one embodiment, the steering motor 110 and the screw 132 of the rear wheel steering device 100 can be arranged along the height direction of the vehicle, and the distance between the central axis of the motor shaft 112 of the steering motor 110 and the axis of the rear wheel 41 is greater than the distance between the central axis of the screw 132 and the axis of the rear wheel 41. In one embodiment, the steering motor 110 may not be located directly above the screw 132, and the steering motor 110 may be tilted relative to the screw 132 in the forward or backward direction of the vehicle. In one embodiment, the steering motor 110 may be located directly above the screw 132, and the plane where the central axis of the motor shaft 112 and the central axis of the screw 132 lie is perpendicular to the forward or backward direction of the vehicle.

[0164] In this embodiment, the steering motor 110 is placed above the screw 132, which can improve the safety of the steering motor 110 and prevent the steering motor 110 from being damaged in structure or electrical connection due to collision, thereby affecting the safety and life of the rear wheel steering gear 100.

[0165] Figure 17 This is a schematic diagram of the arrangement of two rear wheel steering gears in an embodiment of the present application.

[0166] In one embodiment, see Figure 17As shown, the axes of the screw rods 132 of the two rear wheel steering gears 100 coincide with each other, and the screw rods 132 are used to be arranged parallel to the arrangement direction of the two rear wheels 41 along their axial directions.

[0167] In one embodiment, the two rear wheels 41 are arranged along the width direction of the vehicle, and the arrangement direction of the two rear wheels 41 refers to the direction of the line connecting the steering centers of the two rear wheels 41 .

[0168] The axial directions of the screw rods 132 of the two rear wheel steering gears 100 coincide with each other, so that the forces exerted by the two screw rods 132 on the two rear wheels 41 are distributed along the axes of the two screw rods 132, and the forces exerted by the two screw rods 132 on the frame 20 through the housing 150 are all extended in the same direction, which is conducive to optimizing the structure of the frame 20 so that the frame 20 can support and balance the forces exerted by the rear wheel steering gears 100 on the rear wheels 41.

[0169] In one embodiment, see Figure 17 As shown, the two rear-wheel steering gears 100 are configured to be mirror-symmetrical along a plane perpendicular to the axis of the screw 132. In one embodiment, the two rear-wheel steering gears 100 are mirror-symmetrical, with the mirror-symmetrical plane perpendicular to the axis of the screw 132. This allows the two rear-wheel steering gears 100 to be mirror-symmetrically arranged on the vehicle frame along the width direction of the frame, facilitating the installation and structural arrangement of the two rear-wheel steering gears 100 on the vehicle frame 20 and improving the neatness and aesthetics of the assembly of the rear-wheel steering gears 100 on the vehicle frame 20.

[0170] In one embodiment, see Figure 17 As shown, along the axial direction of the screw rod 132 , the distances between the screw rods 132 of the two rear wheel steering gears 100 and the rear wheels 41 connected thereto are the same.

[0171] The two rear wheel steering gears 100 are mirror-symmetrical with respect to the central axis of the vehicle, which can improve the balance of the force exerted on the frame 20 by the two rear wheel steering gears 100 and is beneficial to the arrangement of various components on the frame 20.

[0172] The present application provides a vehicle with a distributed rear wheel locking steering gear, the vehicle includes two rear wheels and at least two rear wheel steering gears, the two rear wheel steering gears are fixed to the frame and arranged between the two rear wheels, each of the two rear wheel steering gears is used to drive one of the two rear wheels to steer; each rear wheel steering gear includes a steering motor, a locking mechanism and a lead screw, along the arrangement direction of the rear wheel steering gear and its corresponding connected rear wheel, the steering motor, the locking mechanism, the lead screw and the rear wheel are arranged in sequence, the steering motor drives the rear wheel to steer through the lead screw, and the steering motor also limits the jumping of the lead screw relative to the frame through the locking mechanism. The present application provides a vehicle with a distributed rear wheel steering drive, the two rear wheel steering gears respectively control the two rear wheels, and the two rear wheel steering gears are respectively provided with a locking mechanism to realize that under distributed drive, the two rear wheel steering gears respectively lock the steering angles of the two rear wheels. Compared with the centralized type, the steering angle change of a single wheel under the distributed drive is more difficult to control, and the harm caused by the different angle offsets of the two rear wheels is greater. The present application sets a locking mechanism on both rear wheel steering gears for protection, and the two locking mechanisms are also easier to achieve coordination between the two. The controller can coordinate the rotation angle of the two locking mechanisms to cooperate with the corresponding control method to prevent the steering angle deviation of the two wheels from being too large, affecting driving safety and the life of the vehicle structure.

[0173] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

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 screw of the lead screw to move axially through the transmission mechanism. One end of the screw is used to drive the rear wheel of one side of the vehicle to steer through the steering tie rod, and the other end of the screw is used to receive the drive of the transmission mechanism through the nut of the lead screw, wherein: The central axis of the motor shaft of the steering motor is used to be arranged parallel to the central axis of the screw, and the distance between the central axis of the motor shaft and the central axis of the screw along the arrangement direction of the screw and the steering motor is greater than the outer ring radius of the stator of the steering motor.

2. The rear wheel steering gear according to claim 1, characterized in that: The transmission mechanism includes two transmission wheels and a belt. The motor shaft is used to drive one of the two transmission wheels to rotate. The one transmission wheel is used to drive the other of the two transmission wheels to rotate through the belt. The other transmission wheel is used to drive the nut to rotate.

3. The rear wheel steering gear according to claim 2, characterized in that: The rear wheel steering gear includes a bearing, the inner ring of the bearing is fixedly connected to the nut, the outer ring of the bearing is used to fix the housing of the rear wheel steering gear, the other transmission wheel is sleeved on the outer periphery of the nut, and the bearing is used to be coaxially arranged in sequence with the other transmission wheel along the axial direction of the screw.

4. The rear wheel steering gear according to claim 3, characterized in that: A projection of the motor shaft along an arrangement direction of the motor shaft and the screw rod at least partially overlaps with the bearing.

5. The rear wheel steering gear according to any one of claims 1 to 4, characterized in that: The lead screw is a trapezoidal lead screw, and the thread lead angle of the screw of the trapezoidal lead screw is less than or equal to 4.5 degrees.

6. The rear wheel steering gear according to any one of claims 1 to 4, characterized in that: The screw is a ball screw, and the balls of the ball screw are accommodated between the nut and the screw.

7. The rear wheel steering gear according to claim 5 or 6, characterized in that: The rear wheel steering gear includes a locking mechanism, the steering motor is used to connect to the transmission mechanism through the locking mechanism, the transmission mechanism is used to drive the nut of the screw to rotate, and the locking mechanism is used to limit the rotation of the transmission mechanism when the steering motor stops rotating.

8. The rear wheel steering gear according to claim 7, characterized in that: The locking mechanism includes a movable part and an output shaft, the output shaft is used to transmit and connect the motor shaft and the transmission mechanism, and the movable part is used to move closer to or farther away from the output shaft to lock or release the output shaft from rotating.

9. The rear wheel steering gear according to any one of claims 1 to 4, characterized in that: The screw comprises a planetary roller screw, and the thread lead angle of the screw of the planetary roller screw is less than 7 degrees.

10. The rear wheel steering gear according to claim 1, characterized in that: The transmission mechanism includes two gears, and the motor shaft drives the nut to rotate by driving the meshing transmission of the two gears.

11. The rear wheel steering gear according to claim 10, characterized in that: The rear wheel steering gear includes a locking mechanism, the steering motor is used to connect one of the gears via the locking mechanism, and the locking mechanism is used to limit the rotation of the two gears when the steering motor stops rotating.

12. The rear wheel steering gear according to any one of claims 1 to 11, characterized in that: The rear wheel steering gear includes a controller, which is used to control the operation of the steering motor. The housing of the steering motor includes a accommodating cavity and a partition, the accommodating cavity is used to accommodate the controller of the steering motor, and the partition is used to separate the stator and the controller.

13. The rear wheel steering gear according to any one of claims 1 to 12, characterized in that: The rear wheel steering gear includes a linear displacement sensor, which is used to detect the axial displacement of the screw of the screw. The linear displacement sensor is a magnetoelectric displacement sensor.

14. A vehicle, characterized in that: The vehicle includes two rear wheel steering gears according to any one of claims 1 to 13, and the two rear wheel steering gears are respectively used to drive the steering of the rear wheels on both sides of the vehicle. The vehicle realizes the outward or inward turning of the two rear wheels through the rear wheel steering gears.

15. The vehicle according to claim 14, characterized in that Along the height direction of the vehicle, the distance between the central axis of the motor shaft and the axis of the rear wheel is equal to the distance between the central axis of the screw and the axis of the rear wheel.

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