Vehicle electric steering gear assembly, vehicle steering system and vehicle

Abstract

The invention discloses a vehicle electric steering gear assembly, a vehicle steering system and a vehicle, and relates to the technical field of vehicle electric steering, and the vehicle electric steering gear assembly comprises a shell, an input assembly, a power assisting assembly, a gear set transmission pair and a lead screw pair; the input end of the input assembly is used for being connected with an external steering transmission mechanism. The power assisting assembly comprises a double-winding motor, a planetary gear transmission pair and a double-loop controller. The output end of the double-winding motor is in transmission connection with the input end of the planetary gear transmission pair, and the double-loop controller is used for receiving an instruction of a vehicle center control so as to control the double-winding motor to drive; the input end of the gear set transmission pair is in transmission connection with the output end of the input assembly and the output end of the planetary gear transmission pair. The input end of the lead screw pair is in transmission connection with the output end of the gear set transmission pair, and the output end of the lead screw pair is in transmission connection with the steering straight pull rod. According to the vehicle electric steering gear assembly, the steering efficiency can be improved, the service life can be prolonged, and the safety level can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile electric power steering, in particular to a vehicle electric power steering assembly, a vehicle steering system and a vehicle. BACKGROUND

[0002] With the development of science and technology, the automobile technology gradually develops towards intelligence, and the auxiliary driving functions such as automatic driving, automatic emergency avoidance and automatic parking of intelligent vehicles must be based on electric control steering; the electric control steering currently mainly includes electro-hydraulic hybrid steering and electric power steering; the electro-hydraulic hybrid steering system also needs to be equipped with a steering oil tank, a steering oil pump, a steering oil pipe and other hydraulic accessories, the overall cost is high and is not conducive to energy saving, environmental protection and the like; the electric power steering currently includes gear rack type electric power steering, circulating ball type electric power steering, synchronous belt ball screw straight pull rod type electric power steering and planetary gear electric power steering, among which the gear rack type electric power steering is mainly used for passenger cars with light front axle load and cannot be applied to commercial vehicle field with heavy front axle load; the circulating ball type electric power steering and the synchronous belt ball screw straight pull rod type electric power steering are limited by the structural strength of the circulating ball transmission pair and the output torque is limited, and can only meet the needs of small commercial vehicles, and the transmission gap is difficult to guarantee when the synchronous belt structure is used; the planetary gear electric power steering has a large reduction transmission ratio, and has no emergency steering function after the electric control part fails, and has low safety. SUMMARY

[0003] The present application aims to provide a vehicle electric power steering assembly, a vehicle steering system and a vehicle to solve the problems of the prior art and improve steering efficiency, service life and safety level.

[0004] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0005] The present application provides a vehicle electric power steering assembly, comprising a body, the body comprising a shell, an input assembly, a power-assisted assembly, a gear set transmission pair and a screw pair; the input assembly is arranged on the shell, and an input end of the input assembly is used for connecting an external steering transmission mechanism; the power-assisted assembly is arranged on the shell and comprises a double-winding motor, a planetary gear transmission pair and a double-loop controller; an output end of the double-winding motor is in transmission connection with an input end of the planetary gear transmission pair, the double-loop controller is in communication connection with the double-winding motor, and the double-loop controller is used for receiving an instruction of a vehicle central control unit to control the double-winding motor to drive; the gear set transmission pair is arranged in the shell, an output end of the input assembly and an output end of the planetary gear transmission pair are in transmission connection with an input end of the gear set transmission pair; the screw pair is arranged on the shell, an output end of the gear set transmission pair is in transmission connection with an input end of the screw pair, and an output end of the screw pair is in transmission connection with a steering straight pull rod.

[0006] Preferably, the input assembly comprises an input shaft, a torsion bar, and an input bevel gear and an output bevel gear, the input shaft is in driving connection with the input bevel gear through the torsion bar, an input end of the input shaft is used for connecting an external steering transmission mechanism; the output bevel gear is in meshing driving connection with the input bevel gear; the output bevel gear is coaxially fixedly connected with an output shaft of the planetary gear transmission pair, and the output shaft of the planetary gear transmission pair is in driving connection with an input end of the gear set transmission pair.

[0007] Preferably, the input assembly further comprises a monitoring member arranged in the housing, the monitoring member is used for monitoring angle torque information of the torsion bar and can be sent to the double-loop controller.

[0008] Preferably, the gear set transmission pair is arranged as a cylindrical gear set transmission pair.

[0009] Preferably, the cylindrical gear set transmission pair comprises a first pinion, a second pinion, a first gear and a second gear; the first pinion is coaxially fixedly sleeved on the output shaft of the planetary gear transmission pair, the first gear is in meshing driving connection with the first pinion, the second pinion is coaxially fixedly connected with the first gear, and the second gear is in meshing driving connection with the second pinion; the second gear is in driving connection with an input end of the screw pair.

[0010] Preferably, the screw pair is arranged as a roller screw transmission pair.

[0011] Preferably, an output end of the screw pair is in driving connection with a steering tie rod through a spherical joint.

[0012] Preferably, the body is symmetrically arranged about a central section.

[0013] The application further provides a vehicle steering system, comprising an external steering transmission mechanism, a steering tie rod, and a vehicle electric power steering assembly as above; the external steering transmission mechanism is in driving connection with an input end of an input assembly of the vehicle electric power steering assembly, and an output end of a screw pair of the vehicle electric power steering assembly is in driving connection with the steering tie rod, which is used for rotating a wheel assembly through a knuckle arm and a steering tie rod.

[0014] The application further provides a vehicle, comprising a wheel assembly, a vehicle central control, and a vehicle steering system as above.

[0015] The application has the following technical effects relative to the prior art:

[0016] The vehicle electric power steering gear assembly, the vehicle steering system and the vehicle provided by the application transmit steering power to an input assembly through an external steering transmission mechanism such as a steering wheel assembly, and can transmit the steering power to a screw rod pair through a gear set transmission pair under the electric power assistance of a power assistance assembly, convert the rotary power into push-pull power of the screw rod pair, and then drive the steering straight pull rod to act, thereby realizing subsequent steering operation. The use of the planetary gear transmission pair, the gear set transmission pair and the screw rod pair can improve the service life, the output torque and the steering efficiency. In addition, the use of the double-winding motor and the double-loop controller has double safety protection, and when winding short circuit, open circuit or controller failure occurs, there is a safety hazard of sudden loss of steering assistance. Through the double-winding motor, the two independent windings can be redundant backups, and when a main winding fault is detected, the double-loop controller can realize seamless switching of the standby winding, thereby ensuring continuous steering assistance without interruption. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0018] Figure 1 The shaft side view of the vehicle electric power steering gear assembly provided by the first embodiment of the application is shown in the figure.

[0019] Figure 2 The cross-sectional view of the vehicle electric power steering gear assembly provided by the first embodiment of the application is shown in the figure.

[0020] Figure 3 The enlarged view of I in the figure. Figure 2 The enlarged view of I in the figure.

[0021] Figure 4 The enlarged view of II in the figure. Figure 2 The enlarged view of II in the figure.

[0022] Figure 5 The enlarged view of III in the figure. Figure 2 The enlarged view of III in the figure.

[0023] Figure 6 The enlarged view of IV in the figure. Figure 2 The enlarged view of IV in the figure.

[0024] Figure 7 The enlarged view of V in the figure. Figure 2 The enlarged view of V in the figure.

[0025] Figure 8 The shell view outside the screw rod pair provided by the first embodiment of the application is shown in the figure.

[0026] Figure 9 The control framework schematic diagram of the double-loop controller provided for the first embodiment of the present application;

[0027] Figure 10 The structural schematic diagram of the vehicle steering system provided for the second embodiment of the present application.

[0028] In the figure: 1 - housing; 2 - input assembly; 21 - input shaft; 22 - torsion bar; 23 - input bevel gear; 24 - output bevel gear; 25 - monitoring member; 3 - external steering transmission mechanism; 4 - assist assembly; 41 - double-winding motor; 42 - planetary gear transmission pair; 421 - sun gear input shaft; 422 - sun gear; 423 - planetary gear; 424 - fixed inner ring; 425 - planetary carrier output shaft; 43 - double-loop controller; 5 - vehicle central control; 6 - gear set transmission pair; 61 - first pinion; 62 - second pinion; 63 - first gear; 64 - second gear; 7 - screw pair; 71 - threaded screw; 72 - roller screw; 73 - roller cage; 74 - threaded screw nut output shaft; 75 - double-row tapered roller bearing; 8 - spherical joint; 9 - steering tie rod; 10 - steering knuckle arm; 11 - steering tie rod; 12 - wheel assembly. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] The purpose of the present application is to provide a vehicle electric steering gear assembly, a vehicle steering system and a vehicle to solve the problems existing in the prior art and improve steering efficiency, service life and safety level.

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment one

[0033] The present embodiment provides a vehicle electric steering gear assembly, please see Figures 1-10, including a body, the body comprising a housing 1, an input assembly 2, an assist assembly 4, a gear set transmission pair 6 and a lead screw pair 7; the input assembly 2 is arranged on the housing 1, and an input end of the input assembly 2 is used for connecting an external steering transmission mechanism 3; the assist assembly 4 is arranged on the housing 1 and comprises a double-winding motor 41, a planetary gear transmission pair 42 and a double-loop controller 43; an output end of the double-winding motor 41 is in transmission connection with an input end of the planetary gear transmission pair 42, the double-loop controller 43 is in communication connection with the double-winding motor 41, and the double-loop controller 43 is used for receiving an instruction of a vehicle central control 5 to be able to control the double-winding motor 41 to drive; the gear set transmission pair 6 is arranged in the housing 1, an output end of the gear set transmission pair 6 is in transmission connection with an output end of the input assembly 2 and an output end of the planetary gear transmission pair 42; the lead screw pair 7 is arranged on the housing 1, an input end of the lead screw pair 7 is in transmission connection with an output end of the gear set transmission pair 6, and an output end of the lead screw pair 7 is in transmission connection with a steering straight pull rod 9.

[0034] The external steering transmission mechanism 3 such as a steering wheel assembly transmits steering power to the input assembly 2 and can transmit the steering power to the lead screw pair 7 through the gear set transmission pair 6 under the electric power assist of the assist assembly 4, converts the rotary power into the push-pull power of the lead screw pair 7, and further can drive the steering straight pull rod 9 to act, realizing subsequent steering operation; wherein the use of the planetary gear transmission pair 42, the gear set transmission pair 6 and the lead screw pair 7 can improve the service life, the output torque and the steering efficiency; in addition, the use of the double-winding motor 41 and the double-loop controller 43 has double safety protection, when winding short circuit, open circuit or controller failure occurs, there is a safety hazard of sudden loss of steering assist; through the double-winding motor 41, two independent windings can be redundant backup, when the main winding fault is detected, the double-loop controller 43 can realize seamless switching of the standby winding, ensuring continuous steering assist without interruption; in this way, the vehicle electric power steering assembly provided by the embodiment can be applied to vehicles with large load such as large commercial vehicles and the like.

[0035] In an optional solution of the embodiment, more preferably, referring to Figure 2 and Figure 3 , the input assembly 2 comprises an input shaft 21, a torsion bar 22, an input bevel gear 23 and an output bevel gear 24, the input shaft 21 is in transmission connection with the input bevel gear 23 through the torsion bar 22, and an input end of the input shaft 21 is used for connecting the external steering transmission mechanism 3; the output bevel gear 24 is in meshing transmission connection with the input bevel gear 23; the output bevel gear 24 is coaxially fixedly connected with an output shaft of the planetary gear transmission pair 42, and the output shaft of the planetary gear transmission pair 42 is in transmission connection with an input end of the gear set transmission pair 6.

[0036] The input shaft 21 is connected with the input bevel gear 23 through the elastic element torsion bar 22. Specifically, one end of the torsion bar 22 is fixed with the input shaft 21 by radial pinning, and the other end of the torsion bar 22 is fixedly connected with the input bevel gear 23. The input bevel gear 23 is in gear engagement with the output bevel gear 24, and the output bevel gear 24 is coaxially fixedly connected with the output shaft of the planetary gear transmission pair 42. Under the assistance of the double-winding motor 41, the double-winding motor 41 outputs the steering assistance to the gear set transmission pair 6 through the output shaft by the speed reduction and torque increasing effect of the planetary gear transmission pair 42.

[0037] In an optional solution of the embodiment, preferably, the input assembly 2 further comprises a monitoring member 25 arranged in the housing 1. The monitoring member 25 is used for monitoring the angle torque information of the torsion bar 22 and can send the information to the double-loop controller 43.

[0038] The monitoring member 25 is arranged as an angle torque sensor. During the steering process, as the steering resistance increases, the elastic element torsion bar 22 generates corresponding torsional deformation. The angle torque sensor converts the torsional deformation into an electrical signal and sends the signal to the double-loop controller 43. The double-loop controller 43 controls the double-winding motor 41 to output corresponding torsion force for power-assisted steering through the planetary gear transmission pair 41.

[0039] In an optional solution of the embodiment, preferably, the gear set transmission pair 6 is arranged as a cylindrical gear set transmission pair.

[0040] The cylindrical gear set transmission pair can further improve the service life, transmission efficiency and output torque. The steering force transmitted from the input assembly 2 or the double-winding motor 41 through the planetary gear transmission pair 42 is further speed-reduced and torque-increased and output to the next-stage screw pair 7.

[0041] In an optional solution of the embodiment, preferably, please refer to Figure 2 and Figure 5 The cylindrical gear set transmission pair comprises a first pinion 61, a second pinion 62, a first gear 63 and a second gear 64. The first pinion 61 is coaxially fixedly arranged on the output shaft of the planetary gear transmission pair 42. The first gear 63 is in gear engagement with the first pinion 61. The second pinion 62 is coaxially fixedly connected with the first gear 63. The second gear 64 is in gear engagement with the second pinion 62. The second gear 64 is in transmission connection with the input end of the screw pair 7.

[0042] The first pinion 61, the second pinion 62, the first gear 63 and the second gear 64 together form a cylindrical gear set transmission pair, the first pinion 61 directly receives the input torque, which is transmitted to the first gear 63, the first gear 63 is coaxially fixedly connected with the second pinion 62 through a connecting shaft, the second pinion 62 rotates synchronously, and the torque is transmitted to the second gear 64, and the second gear 64 transmits the output torque to the screw pair 7; in this way, the steering force transmitted by the input assembly 2 or the double-winding motor 41 through the planetary gear transmission pair 42 can be further decelerated and increased in torque and output to the next screw pair 7; it should be noted that the above-mentioned "large" and "small" are comparative relationships between a plurality of gears included in the cylindrical gear set transmission pair.

[0043] In an optional embodiment of the present embodiment, preferably, the screw pair 7 is a roller screw transmission pair.

[0044] The roller screw transmission pair can further improve transmission efficiency, transmission accuracy and service life. Figure 2 Figure 6 and Figure 7 , specifically including a threaded screw rod 71, a roller screw rod 72, a roller retainer 73, a threaded screw nut output shaft 74 and a double-row tapered roller bearing 75, wherein the threaded screw rod 71 is radially supported by the double-row tapered roller bearing 75 and only rotates, the threaded screw rod 71 and the threaded screw nut output shaft 74 are uniformly distributed with the roller screw rod 72, the three are engaged through threads, and the roller retainer 73 ensures the uniform distribution gap of the roller screw rod 72; one end of the threaded screw rod 71 is coaxially fixedly connected with the second gear 64, and the threaded screw rod 71 converts the low-speed large-torque rotation of the second gear 64 into linear motion of the threaded screw nut output shaft 17, and acts on the steering linkage of the vehicle.

[0045] In an optional embodiment of the present embodiment, preferably, the output end of the screw pair 7 is drivingly connected with the steering straight rod 9 through the spherical joint 8; wherein the spherical joint 8 helps to improve the flexibility and stability of the arrangement.

[0046] In an optional embodiment of the present embodiment, preferably, the body is symmetrically arranged about a central section; specifically, it is symmetrically arranged about a central vertical section, which can adapt to left and right rudder vehicle arrangement, improve flexibility and applicability.

[0047] In an optional embodiment of the present embodiment, preferably, please refer to Figure 2 and Figure 4 ​, the structure of the planetary gear pair 42 can adopt a conventional structure, specifically including a sun gear input shaft 421, a sun gear 422, a planetary gear 423, a fixed inner ring gear 424, and a planetary carrier output shaft 425, the sun gear input shaft 421 is drivingly connected with the double-winding motor 41 to realize power input, the planetary carrier output shaft 425 is coaxially fixedly connected with the output bevel gear 24, and the first pinion 61 is sleeved outside the planetary carrier output shaft 425, and the planetary carrier output shaft 425 realizes power output; the driving engagement action of the planetary gear pair 42 is as follows: the sun gear input shaft 421 rotates under the driving of the double-winding motor 41, the sun gear input shaft 421 is connected with the sun gear 422 by means of a key, the planetary gear 423 rotates around the sun gear 422 under the driving of the sun gear 422 and the meshing fixing of the fixed inner ring gear 424, and the planetary rotation of the planetary gear 423 finally forms the rotational output of the planetary carrier output shaft 425.

[0048] The vehicle electric power steering assembly provided by the embodiment has two steering control modes:

[0049] The power-assisted mode: the driver inputs steering power through the external steering transmission mechanism, and the steering power is converted into linear output through the input shaft 21, the torsion bar 22, the input bevel gear 23, the output bevel gear 24, the cylindrical gear pair, and finally the lead screw pair 7, and then the linear output acts on the vehicle steering straight pull rod 9 through the spherical joint 8, and the straight pull rod pushes the vehicle steering knuckle arm 10 and the steering tie rod 11 to finally make the left and right wheels of the vehicle wheel assembly 12 of the steering axle rotate coordinately; during the steering process, as the steering resistance increases, the torsion bar 22 generates corresponding torsional deformation, and the angular torque sensor converts the torsional deformation into an electrical signal and sends the electrical signal to the double-loop controller 43, and the double-loop controller 43 controls the double-winding motor 41 to output corresponding torsion force through the planetary gear pair 42, the cylindrical gear pair, and the lead screw pair 7 to assist steering.

[0050] The drive-by-wire mode: the double-loop controller 43 combines the angle and angular velocity instructions given by the vehicle central control 5 such as VCU to make the vehicle corresponding rotation, and outputs through a series of structures for speed reduction, torque increase, rotation to linear motion of the planetary gear pair 42, the cylindrical gear pair, and the lead screw pair 7; at the same time, the double-loop controller 43 synchronously uploads the rotation angle of the double-winding motor 41 to the vehicle central control 5 for closed-loop control, so as to realize lane keeping, automatic driving, and other functions through the drive-by-wire mode.

[0051] In the optional scheme of the embodiment, more preferably, please refer to Figure 9The control mode of the dual-winding motor 41 and the dual-loop controller 43 is as follows: the dual-winding motor 41 can adopt a conventional dual-winding assist motor including motor winding one and motor winding two, the dual-loop controller 43 is conventionally provided, including a redundantly provided controller loop one and a controller loop two, the controller loop one and the controller loop two control the motor winding one and the motor winding two respectively, the angle torque sensor transmits the monitored steering wheel angle and direction torque information to the controller loop one and the controller loop two, the vehicle central control 5 speed signal and the control mode input are input to the controller loop one and the controller loop two for control, the controller loop one and the controller loop two control to realize the selection of the assist mode or the steer-by-wire mode, and the driving angle of the motor winding one and the motor winding two of the dual-winding motor 41 is fed back to the corresponding controller loop one and controller loop two for closed-loop control.

[0052] Embodiment Two

[0053] The embodiment provides a vehicle steering system, as shown in Figure 9 including an external steering transmission mechanism 3, a steering straight pull rod 9, and a vehicle electric power steering assembly as in embodiment one; the external steering transmission mechanism 3 is in transmission connection with the input end of the input assembly 2 of the vehicle electric power steering assembly, the output end of the screw pair 7 of the vehicle electric power steering assembly is in transmission connection with the steering straight pull rod 9, and the steering straight pull rod 9 is used to make the left and right wheels of the wheel assembly 12 rotate cooperatively through the steering knuckle arm 10 and the steering cross pull rod 11.

[0054] The external steering transmission mechanism 3 includes a steering wheel, a steering column, and other steering transmission mechanism rotating steering gears to realize power input to the input shaft 21.

[0055] Embodiment Three

[0056] The embodiment provides a vehicle, as shown in Figure 9 including a wheel assembly 12, a vehicle central control 5, and a vehicle steering system as in embodiment two.

[0057] The external steering transmission mechanism 3 such as a steering wheel assembly transmits steering power to the input assembly 2, and can transmit the steering power to the screw pair 7 through the gear set transmission pair 6 under the electric power assistance of the power assistance assembly 4, convert the rotary power into the push-pull power of the screw pair 7, and further drive the steering straight pull rod 9 to act, realizing subsequent steering operation; wherein the use of the planetary gear transmission pair 42, the gear set transmission pair 6 and the screw pair 7 can improve the service life, the output torque and the steering efficiency; in addition, the use of the double-winding motor 41 and the double-loop controller 43 has double safety guarantee, and when winding short circuit, open circuit or controller failure occurs, there is a safety hazard of sudden loss of steering power assistance; through the double-winding motor 41, two groups of independent windings can be redundant backup, when the main winding fault is detected, the double-loop controller 43 can realize seamless switching of the standby winding, and ensure continuous steering power assistance; in this way, the vehicle electric power steering assembly provided by the embodiment can be applied to vehicles with large load such as large commercial vehicles.

[0058] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A vehicle electric steering assembly, characterized in that: The invention comprises a body, wherein the body comprises: Housing (1); An input component (2) is arranged on the housing (1), and an input end of the input component (2) is used to connect to an external steering transmission mechanism (3); A power assist assembly (4) is provided on the housing (1), comprising a dual-winding motor (41), a planetary gear transmission pair (42), and a dual-circuit controller (43); the output end of the dual-winding motor (41) is in transmission connection with the input end of the planetary gear transmission pair (42), the dual-circuit controller (43) is in communication connection with the dual-winding motor (41), and the dual-circuit controller (43) is used to receive instructions from a vehicle central control (5) so as to control the dual-winding motor (41) to drive; A gear train transmission pair (6) is disposed in the housing (1), wherein the input end of the gear train transmission pair (6) is in transmission connection with the output end of the input assembly (2) and the output end of the planetary gear transmission pair (42); and A screw pair (7) is arranged on the housing (1), the input end of the screw pair (7) is transmission-connected to the output end of the gear train transmission pair (6), and the output end of the screw pair (7) is transmission-connected to the steering straight rod (9).

2. The vehicle electric power steering assembly according to claim 1, characterized in that: The input assembly (2) comprises an input shaft (21), a torsion bar (22), an input bevel gear (23), and an output bevel gear (24); the input shaft (21) and the input bevel gear (23) are transmission-connected via the torsion bar (22); the input end of the input shaft (21) is used to connect to an external steering transmission mechanism (3); the output bevel gear (24) is meshed and transmission-connected with the input bevel gear (23); the output bevel gear (24) is coaxially fixedly connected to the output shaft of the planetary gear transmission pair (42); and the output shaft of the planetary gear transmission pair (42) is transmission-connected to the input end of the gear set transmission pair (6).

3. The vehicle electric power steering assembly according to claim 2, characterized in that: The input assembly (2) further comprises a monitoring component (25) disposed in the housing (1), wherein the monitoring component (25) is used to monitor the angular torque information of the torsion bar (22) and can send the information to the dual-loop controller (43).

4. The vehicle electric power steering assembly according to claim 2, characterized in that: The gear set transmission pair (6) is configured as a cylindrical gear set transmission pair.

5. The vehicle electric power steering assembly according to claim 4, characterized in that: The cylindrical gear transmission pair comprises a first small gear (61), a second small gear (62), a first large gear (63) and a second large gear (64); The first small gear (61) is coaxially fixedly sleeved on the output shaft of the planetary gear transmission pair (42); the first large gear (63) is meshed and transmission-connected with the first small gear (61); the second small gear (62) is coaxially fixedly connected with the first large gear (63); the second large gear (64) is meshed and transmission-connected with the second small gear (62); and the second large gear (64) is transmission-connected with the input end of the screw pair (7).

6. The vehicle electric power steering assembly according to claim 1, characterized in that: The screw pair (7) is configured as a roller screw transmission pair.

7. The vehicle electric power steering assembly according to claim 1, characterized in that: The output end of the screw pair (7) is connected to the steering straight rod (9) through a spherical joint (8).

8. The vehicle electric power steering assembly according to claim 1, characterized in that: The body is symmetrically arranged about a central cross section.

9. A vehicle steering system, characterized in that: The invention comprises an external steering transmission mechanism (3), a steering straight tie rod (9), and a vehicle electric steering assembly according to any one of claims 1 to 8; the external steering transmission mechanism (3) is transmission-connected to the input end of an input component (2) of the vehicle electric steering assembly, the output end of a lead screw pair (7) of the vehicle electric steering assembly is transmission-connected to the steering straight tie rod (9), and the steering straight tie rod (9) is used to make a wheel assembly (12) rotate in coordination with each other through a steering knuckle arm (10) and a steering tie rod (11).

10. A vehicle, characterized in that: The invention comprises a wheel assembly (12), a vehicle central control (5) and a vehicle steering system as claimed in claim 9.

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