Rear wheel electric power steering gear assembly and vehicle

Abstract

The rear wheel electric power steering gear assembly comprises a shell, a linear reciprocating motion mechanism and an electric drive assembly, a first containing cavity and a second containing cavity are formed in the shell, and the first containing cavity is formed in the first direction and externally penetrates through the first containing cavity to form two shaft holes; the second accommodating cavity is annularly arranged and communicated with the circumferential direction of the first accommodating cavity; the linear reciprocating motion mechanism comprises a nut, a rolling bearing assembly, a threaded rod and two transmission shafts, and the two transmission shafts are slidably connected to the two shaft holes respectively; the nut is supported in the second containing cavity through the rolling bearing assembly. The threaded rod penetrates through the first containing cavity and the second containing cavity, one end of the threaded rod is connected with a transmission shaft, and the other end of the threaded rod penetrates through the nut and is connected with the other transmission shaft. The threaded rod is in threaded engagement with the nut, and the thread is configured to be a trapezoidal thread; the driving end of the electric driving assembly extends into the second containing cavity from the outside of the shell to be in transmission connection with the nut so as to drive the nut to rotate forwards or backwards. According to the invention, steering assistance can be provided for the rear wheels, and mechanical self-locking is realized.

Description

Technical Field

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

[0002] Electric power steering is a vehicle steering assistance mechanism that uses electric drive to provide power to assist the movement of the tie rod to achieve steering knuckle deflection and wheel steering, thereby improving steering efficiency and meeting the steering assistance needs of mid-to-high-end models and new energy vehicles.

[0003] Electric power steering (EPS) systems are typically used for front-wheel steering. Their large turning radius at low speeds makes parking and U-turns difficult, especially in confined urban spaces. This issue has led to the development of rear-wheel steering technology. However, from a safety perspective, when EPS is used in rear-wheel steering systems, the rear steering unit needs to have a locking capability to ensure the rear wheels' tracking characteristics at high speeds and prevent affecting vehicle handling stability and driving safety when steering is not needed. However, related non-rear-wheel EPS assemblies cannot achieve a self-locking function, requiring additional braking devices to prevent the steering axis from deviating during straight-line driving. This not only results in a bulky and complex rear-wheel steering system structure but also poses a significant safety hazard due to brake failure. Utility Model Content

[0004] In view of the above problems, this application provides a rear wheel electric power steering assembly and a vehicle that can provide steering assistance to the rear wheels and realize the mechanical self-locking of the rear wheel steering system.

[0005] According to one aspect of the embodiments of this application, a rear wheel electric power steering assembly is provided, comprising: a housing, the interior of which has a first accommodating cavity and a second accommodating cavity, the first accommodating cavity being disposed through a first direction and having shaft holes forming externally communicating at both ends of the first direction; the second accommodating cavity being circumferentially disposed around the first accommodating cavity and communicating with the first accommodating cavity; a linear reciprocating motion mechanism, the linear reciprocating motion mechanism including a nut, a rolling bearing assembly, a threaded rod, and two drive shafts, the two drive shafts being slidably connected to the two shaft holes respectively, to be adapted for externally connecting to a wheel steering assembly; the nut being rotatably connected via the rolling bearing assembly. Supported in the second accommodating cavity; a threaded rod passes through the first accommodating cavity and the second accommodating cavity along the first direction, one end of the threaded rod is connected to one of the drive shafts, and the other end passes through the nut and is connected to the other drive shaft; wherein, the outer surface of the threaded rod has an external thread that meshes with the internal thread of the nut, and the internal thread and the external thread are configured to be mutually mating trapezoidal threads; and an electric drive assembly is disposed outside the housing, the housing having a mounting hole communicating with the second accommodating cavity, the drive end of the electric drive assembly extending into the second accommodating cavity through the mounting hole and being connected to the nut for transmission, and the electric drive assembly is configured to be able to drive the nut to rotate forward or backward around the first direction.

[0006] In one exemplary embodiment of this application, the electric drive assembly includes: a motor, the drive end of which extends from a mounting hole into a second receiving cavity and is connected to a nut for transmission; and a controller, which is electrically connected to the motor to control the motor to rotate forward or in reverse.

[0007] In one exemplary embodiment of this application, the motor is fixed to the outside of the housing along a first direction, and the drive end of the motor is connected to the nut via a transmission mechanism. The transmission mechanism is disposed in the second accommodating cavity. The transmission mechanism includes: a drive wheel, which is coaxially connected to the drive end of the motor; a driven wheel, which is sleeved on the outer periphery of the nut and has an interference fit with the nut; and a synchronous belt, which is wrapped around the circumference of the drive wheel and the driven wheel to drive the driven wheel to move synchronously with the drive wheel.

[0008] In one exemplary embodiment of this application, the outer diameter of the driven wheel is larger than the outer diameter of the driving wheel.

[0009] In one exemplary embodiment of this application, the sidewall of the first accommodating cavity is further provided with a groove extending along a first direction, and a slider is slidably connected in the groove, and a threaded rod or one of the drive shafts is connected to the slider.

[0010] In one exemplary embodiment of this application, a displacement sensor is further included. The displacement sensor is electrically connected to the electric drive assembly and is disposed on the housing corresponding to the slide groove. The detection end of the displacement sensor is connected to the slider.

[0011] In one exemplary embodiment of this application, the housing includes a first housing and a second housing disposed opposite to each other along a first direction. The interior of the first housing defines a first chamber extending along the first direction and a second chamber surrounding and communicating with one end of the first chamber. One shaft hole is formed in the side wall of the first chamber away from the end of the second chamber. The interior of the second housing defines a third chamber extending along the first direction and a fourth chamber surrounding and communicating with one end of the third chamber. Another shaft hole is formed in the side wall of the third chamber away from the end of the fourth chamber and corresponds to the shaft hole located in the first chamber in the first direction. The first housing and the second housing are flanged together, and the second chamber and the fourth chamber are enclosed at the flange connection to form a second receiving cavity.

[0012] In one exemplary embodiment of this application, the length of the second housing in the first direction is greater than that of the first housing, and a mounting base for connecting the power supply drive assembly is provided at one end of the second housing near the first housing. The mounting base is provided corresponding to the fourth chamber, and a mounting hole is formed in the mounting base.

[0013] In one exemplary embodiment of this application, the rolling bearing assembly and the electric drive assembly are disposed on the same side in a first direction, and the corresponding mounting base is fixed in the fourth chamber of the second housing.

[0014] According to a second aspect of the embodiments of this application, a vehicle is provided, including any of the above-described rear-wheel electric power steering assemblies.

[0015] This application utilizes the first accommodating cavity of the housing to provide linear motion space for the linear reciprocating motion mechanism, and the second accommodating cavity to provide transmission connection space between the electric drive assembly and the linear reciprocating motion mechanism. This allows the nut to rotate around the first direction under the drive of the electric drive assembly, thereby driving the threaded rod that meshes with the nut through the trapezoidal thread to move axially along the first direction. The linear movement of the threaded rod drives the drive shafts at both ends to perform external work, thereby achieving steering assistance for the rear wheels. At the same time, the threaded rod is locked axially by the threaded engagement of the nut, and can only move axially when the nut rotates, thereby preventing unintended steering actions and ensuring the straight-line stability of the vehicle.

[0016] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the rear wheel electric power steering assembly according to an embodiment of this application is shown;

[0019] Figure 2 A schematic diagram of the internal structure of the rear wheel electric power steering assembly according to an embodiment of this application is shown;

[0020] Figure 3 A cross-sectional view of the rear wheel electric power steering assembly described in an embodiment of this application is shown. Figure 1 ;

[0021] Figure 4 A cross-sectional view of the rear wheel electric power steering assembly described in an embodiment of this application is shown. Figure 2 .

[0022] Explanation of icon numbers:

[0023] 1-Outer shell, 11-First accommodating cavity, 111 / 111'-Shaft hole, 12-Second accommodating cavity, 121-Mounting hole, 13-First housing, 131-First chamber, 132-Second chamber, 14-Second housing, 141-Third chamber, 142-Fourth chamber, 15-Slide groove, 16-Slider, 17-Mounting base

[0024] 2-Linear reciprocating motion mechanism, 21-Nut, 22-Rolling bearing assembly, 23-Threaded rod, 24 / 24'-Drive shaft, 25-Sliding bearing assembly,

[0025] 3-Electric drive assembly, 31-Motor, 32-Controller,

[0026] 4-Transmission mechanism, 41-Driving pulley, 42-Driven pulley, 43-Synchronous belt

[0027] 5-Displacement sensor, 51-Detection end,

[0028] 6 / 6' - Wheel steering assembly.

[0029] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0031] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0032] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present application, and should not be construed as limiting the present application.

[0033] like Figures 1 to 4As shown, this embodiment provides a rear wheel electric power steering assembly, including a housing 1, a linear reciprocating motion mechanism 2, and an electric drive assembly 3. The housing 1 has a first accommodating cavity 11 and a second accommodating cavity 12 inside. The first accommodating cavity 11 is disposed through along a first direction S1, and shaft holes 111 / 111' are formed at both ends of the first direction S1 respectively, communicating with the outside. The second accommodating cavity 12 is circumferentially disposed around the first accommodating cavity 11 and communicates with the first accommodating cavity 11. The radial dimension of the second accommodating cavity 12 is larger than the radial dimension of the first accommodating cavity 11. The housing 1 and its internal accommodating cavities can provide support and movement space for the linear reciprocating motion mechanism 2 and the electric drive assembly 3. The linear reciprocating motion mechanism 2 includes a nut 21, a rolling bearing assembly 22, a threaded rod 23, and two drive shafts 24 / 24'. The two drive shafts 24 / 24' are slidably connected to the two shaft holes 111 / 111' respectively, so as to be suitable for external connection of the wheel steering assembly. Part 6 / 6'; Nut 21 is supported in the second accommodating cavity 12 by a rolling bearing assembly 22 and can rotate about the first direction S1; Threaded rod 23 passes through the first accommodating cavity 11 and the second accommodating cavity 12 along the first direction S1, one end of threaded rod 23 is connected to one of the drive shafts 24, and the other end passes through nut 21 and is connected to the other drive shaft 24'; wherein, the middle part of threaded rod 23 has an external thread that meshes with the internal thread of nut 21, and the internal thread and external thread are configured to be mutually mating trapezoidal threads, and when threaded rod 23 passes through nut 21, the internal and external threads of the two mesh with each other; Electric drive assembly 3 can be fixed to the outside of housing 1 by bolts, housing 1 has a mounting hole 121 that communicates with the second accommodating cavity 12, the drive end of electric drive assembly 3 extends into the second accommodating cavity 12 from the mounting hole 121 and is connected to nut 21 for transmission, and electric drive assembly 3 is configured to drive nut 21 to rotate forward or backward about the first direction S1. In this way, driven by the electric drive assembly 3, the nut 21 can rotate around the first direction S1 in the second accommodating cavity 12, thereby driving the threaded rod 23, which is engaged with it by the trapezoidal thread, to move axially along the first direction S1. The linear movement of the threaded rod 23 drives the drive shafts 24 / 24' at both ends to do work externally, thereby realizing steering assistance for the rear wheels. At the same time, the threaded rod 23 is locked axially by the threaded engagement of the nut 21, and can only move axially when the nut 21 rotates, thereby preventing unexpected steering actions and ensuring the straight-line stability of the vehicle.

[0034] It is understandable that the sliding connection of the aforementioned drive shaft 24 / 24' at the shaft hole 111 / 111' can be achieved by providing a sliding bearing assembly 25 on the inner wall of the shaft hole 111 / 111'. The aforementioned wheel steering assembly 6 / 6' can be a steering tie rod assembly or a fork linkage assembly connected to the rear wheel steering knuckle. When the threaded rod 23 moves axially, it pushes the wheel steering assemblies 6 / 6' at both ends to move synchronously, thereby driving the rear wheel steering knuckle to rotate and realizing the steering of the vehicle's rear wheels.

[0035] In some embodiments, such as Figures 1 to 3 As shown, the electric drive assembly 3 includes a motor 31 and a controller 32. The drive end of the motor 31 extends from the outside of the housing 1 through the mounting hole 121 into the second accommodating cavity 12 and is connected to the nut 21. The controller 32 is electrically connected to the motor 31 to control the motor 31 to rotate forward or backward, thereby driving the nut 21 to rotate clockwise or counterclockwise around the axis of the threaded rod 23, i.e., the first direction S1, and causing the threaded rod 23 to move left or right along the axis, so as to realize the left or right turn of the vehicle's rear wheels. At the same time, the controller 32 can precisely control the speed and steering angle of the motor 31 to realize the precise steering of the vehicle's rear wheels. The controller 32 can also realize the synchronous steering of the rear wheels and the front wheels in the same direction, which helps to improve the vehicle's turning performance at low speeds and tracking characteristics at high speeds.

[0036] It is understandable that the controller 32 can use two sets of electronic control units to perform control, one set of electronic control units as the main electronic control unit and the other set as a backup redundancy auxiliary electronic control unit. When the main electronic control unit fails, the auxiliary electronic control unit can be activated to participate in the control of the motor 31, thereby reducing the failure rate of the rear wheel electric power steering assembly.

[0037] Specifically, such as Figure 1 and Figure 3 As shown, the motor 31 can be fixed to the outside of the housing 1 along the first direction S1, so that the rotation axis of the drive end of the motor 31 is parallel to the first direction S1. Then, the drive end of the motor 31 is connected to the nut 21 through the transmission mechanism 4. The transmission mechanism 4 is set in the second accommodating cavity 12 and includes a drive wheel 41, a driven wheel 42 and a synchronous belt 43. The drive wheel 41 is coaxially connected to the drive end of the motor 31. The driven wheel 42 is sleeved on the outer periphery of the nut 21 and is interference-fitted with the nut 21. The synchronous belt 43 is wrapped around the circumference of the drive wheel 41 and the driven wheel 42 to drive the driven wheel 42 to move synchronously with the drive wheel 41. Through the above-mentioned transmission mechanism 4, the electric drive assembly 3 can be set in the same direction as the extension direction of the housing in the overall direction. This not only allows for reasonable allocation of space and makes the overall structure compact, reducing space occupation, but also provides a fast response speed and effectively improves the vehicle's handling performance.

[0038] Furthermore, such as Figure 3 As shown, the outer diameter of the driven wheel 42 is set to be larger than that of the driving wheel 41. This reduces the rotational speed of the driven wheel 42 and increases the torque, thereby improving steering flexibility and helping the driver to better control the vehicle and reduce the risk of skidding and loss of control.

[0039] In some embodiments, such as Figure 2As shown, the side wall of the first accommodating cavity 11 is also provided with a sliding groove 15 extending along the first direction S1. A slider 16 is slidably connected in the sliding groove 15. The threaded rod 23 or one of the drive shafts 24 or 24' is connected to the slider 16, which can prevent the drive shaft 24 / 24' and the threaded rod 23 from rotating around the first direction S1, and does not affect the movement of the threaded rod 23 and the drive shaft 24 / 24' in the first direction S1, thereby avoiding unexpected steering actions of the rear wheels of the vehicle and ensuring the straight-line stability of the vehicle.

[0040] For example, such as Figure 2 As shown, on the side where the electric drive assembly 3 is located, a slide groove 15 extending along the first direction S1 is opened on the side wall of the first accommodating cavity 11, and a slider 16 that can slide along the length direction of the slide groove 15 is provided in the slide groove 15. A threaded hole is opened in the middle of the drive shaft 24' corresponding to the position of the slide groove 15. A screw is used to fix the slider 16 to the threaded hole, so that the drive shaft 24' is slidably connected to the slide groove 15 through the slider 16. This avoids the drive shaft 24' and its connected threaded rod 23 from rotating around the first direction S1 without affecting the movement of the drive shaft 24' and its connected threaded rod 23 in the first direction S1.

[0041] Furthermore, such as Figure 1 and Figure 2 As shown, the rear wheel electric power steering assembly is also equipped with a displacement sensor 5. The displacement sensor 5 is electrically connected to the controller 32 of the electric drive assembly 3 and is disposed on the housing 1 corresponding to the slide groove 15. The detection end 51 of the displacement sensor 5 is connected to the slider 16. When the detection end 51 moves along the slide groove 15 with the slider 16, it can detect the displacement distance of the drive shaft 24 / 24' and its connected threaded rod 23 in the first direction S1. In this way, the steering angle of the rear wheel of the vehicle can be obtained based on the detected displacement data, which helps to improve the handling performance of the vehicle and help the driver to better control the vehicle. During straight driving, the controller 32 can also control the electric drive assembly 3 to drive the linear reciprocating motion mechanism 2 to reset based on the obtained displacement data, thereby improving the tracking characteristics and straight-line stability of the vehicle at high speeds.

[0042] In some embodiments, such as Figures 1 to 4As shown, the outer casing 1 includes a first housing 13 and a second housing 14 disposed opposite to each other along a first direction S1. The interior of the first housing 13 defines a first chamber 131 extending along the first direction S1 and a second chamber 132 surrounding one end of the first chamber 131 and communicating with the first chamber 131. A shaft hole 111 is formed in the side wall of the first chamber 131 away from the end of the second chamber 132. The interior of the second housing 14 defines a third chamber 141 extending along the first direction S1 and a second chamber 142 surrounding one end of the third chamber 141. The fourth chamber 142, which is connected to the third chamber 141, has another shaft hole 111' opened on the side wall of the third chamber 141 away from the fourth chamber 142, and corresponds to the shaft hole 111 located in the first chamber 131 in the first direction S1; the first housing 13 and the second housing 14 are connected by a flange on opposite inner sides in the first direction S1. At this time, the second chamber 132 and the fourth chamber 142 are enclosed at the flange connection to form the second accommodating cavity 12, and the first chamber 131 and the third chamber 141 are also connected to form the first accommodating cavity 11. Since the second accommodating cavity 12 needs to accommodate the transmission mechanism 4, the nut 21, and the rolling bearing assembly 22, and its radial dimension is relatively large, the outer shell 1 is designed as a split type with the first shell 13 and the second shell 14 at the second accommodating cavity 12, which can effectively meet the installation requirements of the various components inside the accommodating cavity; at the same time, by connecting the first shell 13 and the second shell 14 into one unit through the flange connection, the first shell 13 and the second shell 14 can be firmly connected, ensuring the structural stability and sealing effectiveness of the second accommodating cavity 12.

[0043] In some embodiments, such as Figures 2 to 4As shown, to achieve a compact overall structure, the electric drive assembly 3 is positioned in the same direction as the extension direction of the housing. Simultaneously, to ensure balanced force distribution on the rear wheel electric power steering assembly in the first direction S1, the electric drive assembly 3 needs to be positioned near the center of the housing 1 in the first direction S1. Since the drive end of the motor 31 is located at the end of the electric drive assembly 3, and the second accommodating cavity 12 needs to be designed to correspond to the orientation of the drive end of the motor 31, the orientation of the second accommodating cavity 12 in the first direction S1 is offset from the center of the housing 1. Therefore, the split-design housing 1 is divided into a first housing 13 and a second housing 14 of different lengths at the second accommodating cavity 12. In this embodiment, the length of the second housing 14 in the first direction S1 is greater than that of the first housing 13. A mounting base 17 for connecting the electric drive assembly 3 is provided at the end of the second housing 14 near the first housing 13. The mounting base 17 corresponds to the fourth chamber 142, and a mounting hole 121 is formed in the mounting base 17. Thus, the electric drive assembly 3 can be mounted on the larger second housing 14, and the drive end of the motor 31 can extend from the mounting hole 121 into the second receiving cavity 12 and be connected to the nut 21. This satisfies the goal of balancing the force on the rear wheel electric power steering assembly in the first direction S1, and also optimizes the torque transmission direction by utilizing the larger structural size of the second housing 14, improving the load-bearing capacity of the mounting base 17 to ensure the connection stability of the electric drive assembly 3 to the outside of the housing.

[0044] Furthermore, such as Figure 3 As shown, the rolling bearing assembly 22 and the electric drive assembly 3 are arranged on the same side in the first direction S1, and the corresponding mounting base 17 is fixed in the fourth chamber 142 of the second housing 14. At this time, the rotating and fixed ends of the motor 31 and the nut 21 are both located in the same housing with a larger size, namely the second housing 14. The fixed end of the rolling bearing assembly 22 on the outer shell 1 and the driving end of the motor 31 on the fixed end of the outer shell 1 can be radially aligned, thereby optimizing the torque transmission direction, reducing the radial shear force of the motor 31 and the nut 21 on the outer shell 1 during rotation, and improving the structural stability of the outer shell 1.

[0045] In another embodiment, a vehicle is also provided, including the rear-wheel electric power steering assembly described above. For other structures and working principles of the rear-wheel electric power steering assembly, please refer to the above description of the embodiments of the rear-wheel electric power steering assembly. Since the rear-wheel electric power steering assembly has the aforementioned technical effects, a vehicle having this rear-wheel electric power steering assembly should also have the corresponding technical effects, which will not be repeated here.

[0046] It is understood that, unless otherwise expressly specified and limited, the terms "assembly," "connection," etc., in this application should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified. The terms "some embodiments," "exemplarily," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application.

[0048] The illustrative expressions of the terms used above do not necessarily refer to the same embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples, without contradiction.

[0049] Although embodiments of this application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can modify, substitute, and vary the above embodiments within the scope of this application. Therefore, any changes or modifications made in accordance with the claims and description of this application should fall within the scope of this patent application.

Claims

1. A rear-wheel electric power steering assembly, characterized in that, include: The outer casing has a first accommodating cavity and a second accommodating cavity inside. The first accommodating cavity is disposed through a first direction and has shaft holes that communicate with the outside formed at both ends of the first direction. The second accommodating cavity is disposed around the first accommodating cavity in the circumferential direction and communicates with the first accommodating cavity. A linear reciprocating motion mechanism includes a nut, a rolling bearing assembly, a threaded rod, and two drive shafts. The two drive shafts are slidably connected to two shaft holes for external connection to a wheel steering assembly. The nut is rotatably supported in a second accommodating cavity via the rolling bearing assembly. The threaded rod passes through the first and second accommodating cavities along a first direction. One end of the threaded rod is connected to one of the drive shafts, and the other end passes through the nut and is connected to the other drive shaft. The outer surface of the threaded rod has an external thread that meshes with the internal thread of the nut, and the internal and external threads are configured as mutually mating trapezoidal threads. An electric drive assembly is disposed outside the housing. The housing has a mounting hole that communicates with the second accommodating cavity. The drive end of the electric drive assembly extends into the second accommodating cavity through the mounting hole and is connected to the nut in a transmission manner. The electric drive assembly is configured to drive the nut to rotate clockwise or counterclockwise around the first direction.

2. The rear wheel electric power steering assembly according to claim 1, characterized in that, The electric drive assembly includes: A motor, the drive end of which extends into the second accommodating cavity through the mounting hole and is connected to the nut for transmission; and A controller, which is electrically connected to the motor, is used to control the motor to rotate forward or in reverse.

3. The rear wheel electric power steering assembly according to claim 2, characterized in that, The motor is fixed to the outside of the housing along the first direction. The drive end of the motor is connected to the nut via a transmission mechanism. The transmission mechanism is disposed within the second accommodating cavity. The transmission mechanism includes: A drive wheel, which is coaxially connected to the drive end of the motor; Driven wheel, the driven wheel is sleeved on the outer periphery of the nut and is interference-fitted with the nut; and A timing belt is provided around the circumference of the driving wheel and the driven wheel to drive the driven wheel to move synchronously with the driving wheel.

4. A rear-wheel electric power steering assembly according to claim 3, characterized in that, The outer diameter of the driven wheel is larger than the outer diameter of the driving wheel.

5. A rear-wheel electric power steering assembly according to claim 1, characterized in that, The side wall of the first accommodating cavity is also provided with a sliding groove extending along a first direction, and a slider is slidably connected in the sliding groove. The threaded rod or one of the drive shafts is connected to the slider.

6. A rear-wheel electric power steering assembly according to claim 5, characterized in that, It also includes a displacement sensor, which is electrically connected to the electric drive assembly and is disposed on the housing corresponding to the slide groove, and the detection end of the displacement sensor is connected to the slider.

7. A rear-wheel electric power steering assembly according to any one of claims 1-6, characterized in that, The outer casing includes a first housing and a second housing disposed opposite to each other along the first direction. The interior of the first housing defines a first chamber extending along the first direction and a second chamber surrounding and communicating with one end of the first chamber. One of the shaft holes is formed in the side wall of the first chamber away from the end of the second chamber. The interior of the second housing defines a third chamber extending along the first direction and a fourth chamber surrounding and communicating with one end of the third chamber. Another shaft hole is formed in the side wall of the third chamber away from the end of the fourth chamber and corresponds to the shaft hole located in the first chamber in the first direction. The first housing is flanged to the second housing, and the second chamber and the fourth chamber are enclosed at the flange connection to form the second receiving cavity.

8. A rear-wheel electric power steering assembly according to claim 7, characterized in that, The second housing is longer than the first housing in the first direction. A mounting base for connecting the electric drive assembly is provided at one end of the second housing near the first housing. The mounting base is provided corresponding to the fourth chamber. The mounting hole is opened in the mounting base.

9. A rear-wheel electric power steering assembly according to claim 8, characterized in that, The rolling bearing assembly and the electric drive assembly are disposed on the same side in the first direction, and are fixed in the fourth chamber of the second housing corresponding to the mounting base.

10. A vehicle, characterized in that, Includes the rear wheel electric power steering assembly as described in any one of claims 1-9.

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