Vehicle steering device, power-assisted system and power-assisted steering control method

Abstract

The invention relates to the technical field of vehicles, in particular to a vehicle steering device, a power-assisted system and a power-assisted steering control method. The vehicle steering device comprises a vehicle unit and a steering transmission unit, the vehicle unit comprises a steering wheel and wheels, the steering transmission unit comprises a first cylindrical gear, a transmission lead screw and a face gear, the first cylindrical gear is connected with the steering wheel, the wheels are arranged at the two ends of the transmission lead screw respectively, and the face gear is fixedly arranged and matched with the transmission lead screw. And the first cylindrical gear is meshed with the face gear. The power assisting system comprises a controller, an angle sensor, a power assisting motor and a second cylindrical gear, and the second cylindrical gear is connected with the first cylindrical gear in an engaged mode. The rotating speed of the first cylindrical gear is reduced through the face gear, so that torque is increased to achieve speed reduction, transmission efficiency is improved through lead screw transmission, abrasion of transmission parts is reduced, a steering wheel rotates to drive the transmission lead screw to transversely pull wheels on the two sides to make a turn, and the assembly difficulty is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and in particular to a vehicle steering device, a power steering system and a power steering control method. Background Art

[0002] The steering mechanism is an important part of the vehicle's steering system. It is a mechanism that can deflect the wheels to achieve the steering of the car. The driver can change the driving direction by operating the steering wheel, which will deflect the wheels on the road at a certain angle through a set of transmission mechanisms to ensure the safe and stable driving of the car.

[0003] As for the steering mechanism, the traditional mechanical steering mechanism is composed of a steering control mechanism, a steering gear and a steering transmission mechanism. Basically, all transmission steering structures are composed of many shaft parts and steering parts such as universal joints, and a pair of meshing rack and pinion gears. The linear motion of the rack drives the tie rod to move horizontally, and then converts it into wheel deflection through the steering knuckle, thereby realizing wheel steering. However, the existing transmission steering structure has the following disadvantages: its structure is difficult to assemble, the space volume is large, it is not easy to arrange, and the steering control accuracy is low. Especially after long-term operation, excessive wear between the gear and the rack will cause steering control errors and abnormal noises in the steering system. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a vehicle steering device, a power steering system and a power steering control method to solve the problems in the prior art that the transmission steering structure of the vehicle is easy to wear, resulting in steering control errors, and is difficult to assemble.

[0005] The present invention discloses a vehicle steering device, comprising a vehicle unit and a steering transmission unit, wherein the vehicle unit comprises a steering wheel and wheels arranged on a vehicle body, and the steering transmission unit comprises a first cylindrical gear, a transmission screw and a face gear, wherein the first cylindrical gear is connected to the steering wheel so that the first cylindrical gear and the steering wheel rotate synchronously, the transmission screw is perpendicular to the axial direction of the first cylindrical gear, and the wheels are respectively arranged at both ends of the transmission screw, the face gear is fixedly arranged on the vehicle body, and the face gear is matched with the transmission screw to form a screw pair, and the first cylindrical gear is meshed and connected with the face gear.

[0006] Optionally, the steering transmission unit further includes a transmission shaft, one end of which is connected to the middle of the steering wheel, and the first cylindrical gear is arranged on the other end of the transmission shaft.

[0007] Optionally, the face gear includes a wheel body and gear teeth, the cross-section of the wheel body is a "T"-shaped structure, including a first wheel portion and a second wheel portion, the outer diameter of the first wheel portion is larger than the outer diameter of the second wheel portion, the gear teeth are arranged on the end face of the first wheel portion away from the second wheel portion, and the gear teeth are arranged along the outer edge of the end face of the first wheel portion, and an assembly hole that passes through the first wheel portion and the second wheel portion is also provided in the middle portion of the wheel body, an internal thread is provided in the assembly hole, and an external thread that cooperates with the internal thread for transmission is provided on the outer wall of the transmission screw.

[0008] Optionally, the steering transmission unit further comprises a bearing seat arranged on the vehicle body, and the second wheel portion is rotatably connected to the bearing seat.

[0009] Optionally, the bearing seat includes a base plate arranged on the vehicle body, and a positioning plate arranged on the base plate, the plate surface of the base plate is parallel to the transmission screw, the positioning plate is perpendicular to the plate surface of the base plate, and a positioning hole is opened on the positioning plate, a bearing is arranged on the outer wall of the second wheel part, and the second wheel part is rotatably connected in the positioning hole through the bearing.

[0010] Optionally, the steering transmission unit further includes steering tie rods arranged at both ends of the transmission screw, and the ends of the transmission screw are connected to the steering knuckles of the wheels through the steering tie rods on the corresponding sides.

[0011] Optionally, the end of the transmission screw is provided with relatively arranged flat ears, and the flat ears are provided with a first connecting hole. The end of the steering rod away from the wheel is provided with a flat end head which fits and is inserted between the two flat ears, and the flat end head is provided with a second connecting hole. A bolt is provided between the first connecting hole and the second connecting hole, and the connecting ear is connected to the flat end head on the corresponding side through the bolt.

[0012] The present invention also discloses a power-assisting system, comprising the above-mentioned vehicle steering device, and a controller, an angle sensor, a power-assisting motor and a second cylindrical gear arranged on a vehicle body, wherein the angle sensor is used to sense the rotation angle of the steering wheel, and the controller is electrically connected to the angle sensor and the power-assisting motor respectively, and the second cylindrical gear is arranged on the output end of the power-assisting motor, and the second cylindrical gear is meshingly connected to the first cylindrical gear.

[0013] Optionally, a transmission shaft is arranged between the steering wheel and the first cylindrical gear, and the power-assisting system also includes a toothed disk arranged on the transmission shaft, the toothed disk includes a disk body, and a plurality of disk teeth distributed on the outer ring wall of the disk body along the circumferential direction, and the angle sensor includes a light source arranged on one side of the disk teeth, and a photosensitive receiver arranged on the other side of the disk teeth, and the photosensitive receiver corresponds to the position of the light source.

[0014] The present invention also discloses a power steering control method, which adopts the above-mentioned power steering system. The power steering control method comprises: When the vehicle turns, the driver turns the steering wheel to drive the first cylindrical gear to rotate, and the face gear cooperates with the first cylindrical gear to reduce speed, and drives the transmission screw to move laterally, so as to pull the wheels on both sides to deflect and realize turning; In response to the rotation of the steering wheel, the angle sensor synchronously acquires a rotation angle signal of the steering wheel and transmits the signal to the controller; According to the received rotation angle signal, the controller controls whether to start the power assist motor according to a preset judgment logic; When the controller determines that the received rotation angle signal satisfies the preset judgment logic, no control instruction is output, and the power assist motor remains in a stopped state; When the controller determines that the received rotation angle signal does not satisfy the preset judgment logic, it outputs a control instruction to control the power-assisting motor to start, and drives the second cylindrical gear to drive the first cylindrical gear to rotate to perform steering assistance.

[0015] Compared with the prior art, the vehicle steering device, power steering system and power steering control method provided by the embodiments of the present invention have the following beneficial effects: By setting a steering transmission unit between the steering wheel and the wheel, when the vehicle needs to turn, the steering wheel is rotated to drive the first cylindrical gear to rotate, and the face gear and the first cylindrical gear are used to cooperate to achieve a 90° change in the rotation direction of the power. In this process, the face gear reduces the rotation speed of the first cylindrical gear to increase the torque to achieve deceleration. At this time, the face gear and the transmission screw are used to cooperate to drive the transmission screw to move laterally to pull the wheels on both sides to deflect and achieve turning. The high precision of the screw transmission improves the transmission efficiency and effectively reduces the wear of the transmission parts. The present invention adopts face gear transmission, and its transmission form has a large transmission ratio, is insensitive to the axial installation error of small-sized cylindrical gears, and reduces the difficulty of assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which: Figure 1 A schematic diagram of the overall structure of a vehicle steering device provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a face gear provided by an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a transmission screw provided in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of the toothed disk and the angle sensor provided in an embodiment of the present invention.

[0017] The reference numerals in the figures are: 1. Vehicle unit; 11. Steering wheel; 12. Wheel; 2. Steering transmission unit; 21. First cylindrical gear; 22. Transmission screw; 221. External thread; 222. Flat ear; 223. First connecting hole; 23. Face gear; 231. First wheel section; 232. Second wheel section; 233. Gear teeth; 234. Internal thread; 24. Transmission shaft; 25. Bearing seat; 251. Bottom plate; 252. Positioning plate; 26. Steering rod; 261. Flat end; 3. Controller; 4. Angle sensor; 5. Power-assisting motor; 6. Second cylindrical gear; 7. Toothed disc; 71. Disc body; 72. Disc teeth. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.

[0019] The present invention discloses a vehicle steering device, such as Figure 1 As shown, it includes a vehicle unit 1 and a steering transmission unit 2. The vehicle unit 1 includes a steering wheel 11 and a wheel 12 arranged on the vehicle body. The steering transmission unit 2 includes a first cylindrical gear 21, a transmission screw 22 and a face gear 23. The first cylindrical gear 21 is connected to the steering wheel 11 so that the first cylindrical gear 21 and the steering wheel 11 rotate synchronously. The transmission screw 22 is perpendicular to the axial direction of the first cylindrical gear 21, and the wheels 12 are respectively arranged at both ends of the transmission screw 22. The face gear 23 is fixedly arranged on the vehicle body, and the face gear 23 is matched with the transmission screw 22 to form a screw pair, and the first cylindrical gear 21 is meshed and connected with the face gear 23.

[0020] Through the implementation of the above vehicle steering device embodiment, a steering transmission unit 2 is arranged between the steering wheel 11 and the wheel 12. When the vehicle needs to turn, the steering wheel 11 is rotated to drive the first cylindrical gear 21 to rotate, and the face gear 23 cooperates with the first cylindrical gear 21 to achieve a 90° change in the direction of rotation of the power, that is, the input power generated by the rotation of the steering wheel 11 is transferred to the wheels 12 on both sides of the vehicle body with a 90° change in direction. In this process, the face gear 23 reduces the speed of the first cylindrical gear 21 to increase the torque to achieve deceleration, so as to effectively improve the driving efficiency of steering the wheel 12. At this time, the face gear 23 and the transmission screw 22 are used. Since the face gear 23 is fixedly arranged on the vehicle body, when the first cylindrical gear 21 drives the face gear 23 to rotate, it will drive the transmission screw 22 to move horizontally, so as to pull the wheels 12 on both sides to deflect and realize turning, thereby utilizing the high precision of the screw transmission to improve the transmission efficiency and effectively reduce the wear of the transmission parts. The present invention adopts the face gear 23 transmission, which has a large transmission ratio, high strength, and is insensitive to the axial installation error of the small-sized cylindrical gear. Therefore, after using the face gear 23 transmission, the layout space of the transmission device can be greatly reduced, and the assembly difficulty is reduced. In addition, the inner ring of the face gear 23 is used as the outer ring of the transmission screw 22 for transmission, which reduces the number of parts, simplifies the device structure, and reduces the difficulty of installation and debugging.

[0021] Furthermore, the steering transmission unit 2 further includes a transmission shaft 24 , one end of which is connected to the middle of the steering wheel 11 , and the first cylindrical gear 21 is disposed on the other end of the transmission shaft 24 .

[0022] By implementing the above vehicle steering device embodiment, the transmission shaft 24 is used to connect the steering wheel 11 and the first cylindrical gear 21, providing a relatively wide space between the steering wheel 11 and the wheel 12. This layout helps to optimize the space of the transmission system in the vehicle, and provides a stable mechanical connection between the steering wheel 11 and the first cylindrical gear 21, making the steering operation more direct and efficient. Preferably, the transmission shaft 24 is rotatably arranged on the vehicle body.

[0023] Furthermore, combined with Figure 2 and Figure 3 As shown, the face gear 23 includes a wheel body and gear teeth 233. The cross section of the wheel body is a "T"-shaped structure, including a first wheel portion 231 and a second wheel portion 232. The outer diameter of the first wheel portion 231 is larger than the outer diameter of the second wheel portion 232, and the gear teeth 233 are arranged on the end face of the first wheel portion 231 away from the second wheel portion 232, and the gear teeth 233 are arranged along the outer edge of the end face of the first wheel portion 231. The middle part of the wheel body is also provided with an assembly hole that passes through the first wheel portion 231 and the second wheel portion 232. An internal thread 234 is provided in the assembly hole, and an external thread 221 that cooperates with the internal thread 234 for transmission is provided on the outer wall of the transmission screw 22.

[0024] Through the implementation of the above vehicle steering device embodiment, the assembly hole is set in the middle of the wheel body of the face gear 23. By assembling the transmission screw 22 with the face gear 23 along the assembly hole, and matching the internal thread 234 in the assembly hole with the external thread 221 on the transmission screw 22, the inner ring of the assembly hole of the face gear 23 is used as the outer ring of the transmission screw 22 for transmission, that is, when the first cylindrical gear 21 drives the face gear 23 to rotate, it will drive the transmission screw 22 to move horizontally. The number of parts is reduced, the device structure is simplified, and the difficulty of installation and debugging can be reduced. And by utilizing the characteristics of high transmission efficiency and high transmission accuracy of the screw, the transmission efficiency of the present invention is improved and the wear of the transmission parts is reduced. At the same time, by utilizing the "T"-shaped structure of the cross section of the wheel body, the gear teeth 233 are distributed on the end face of the first wheel part 231 with a large outer diameter, so as to ensure stable transmission between the face gear 23 and the transmission screw 22, and by increasing the number of teeth of the face gear 23, the rotation speed of the input power is further reduced to provide the transmission screw 22 with a larger torque and a lower rotation speed.

[0025] Further, look back Figure 1 The steering transmission unit 2 also includes a bearing seat 25 arranged on the vehicle body, and the second wheel portion 232 is rotatably connected to the bearing seat 25.

[0026] Through the implementation of the above-mentioned vehicle steering device embodiment, the bearing seat 25 is used as a supporting structure to provide a reliable installation support position for the face gear 23, ensuring that the face gear 23 can rotate smoothly and avoiding the face gear 23 from shifting during the rotation process, which helps to improve the response speed and accuracy of the vehicle steering.

[0027] Furthermore, the bearing seat 25 includes a bottom plate 251 disposed on the vehicle body, and a positioning plate 252 disposed on the bottom plate 251. The plate surface of the bottom plate 251 is parallel to the transmission screw 22, the positioning plate 252 is perpendicular to the plate surface of the bottom plate 251, and a positioning hole is provided on the positioning plate 252. A bearing is provided on the outer wall of the second wheel portion 232, and the second wheel portion 232 is rotatably connected in the positioning hole through the bearing.

[0028] By implementing the above-mentioned vehicle steering device embodiment, the face gear 23 can be accurately positioned by using the positioning hole provided on the positioning plate 252, thereby ensuring the stability of the transmission between the face gear 23 and the transmission screw 22. The bearing provided on the second wheel portion 232 can provide higher stability and rotation efficiency, thereby reducing the difficulty of steering caused by unstable connection. The friction and wear caused by the direct contact between the face gear 23 and the bearing seat 25 can also be effectively reduced, thereby extending the service life of the face gear 23.

[0029] Furthermore, the steering transmission unit 2 further includes steering tie rods 26 disposed at both ends of the transmission screw 22 , and the ends of the transmission screw 22 are connected to the steering knuckles of the wheels 12 through the steering tie rods 26 on the corresponding sides.

[0030] Through the implementation of the above vehicle steering device embodiment, since the transmission screw 22 is usually located at the center of the vehicle, and the wheels 12 are distributed on both sides of the vehicle, the steering rod 26 is used to allow the necessary adjustment space between the wheel 12 and the transmission screw 22 to adapt to the changes in the positioning and steering geometry of the wheel 12, so that the wheel 12 and the transmission screw 22 are connected by the steering rod 26, so that the steering of the vehicle can more flexibly adjust the angle of the wheel 12, so as to provide more precise steering control in different situations. At the same time, the weight and rotational movement of the wheel 12 are prevented from directly acting on the transmission screw 22, and the steering rod 26 is used as an intermediate connecting member to disperse these forces and prevent large friction and wear.

[0031] Furthermore, combined with Figure 1 and Figure 3 As shown, the end of the transmission screw 22 is provided with a flat ear 222 arranged opposite to each other, and the flat ear 222 is provided with a first connection hole 223. The end of the steering tie rod 26 away from the wheel 12 is provided with a flat end 261 that fits and is inserted between the two flat ears 222, and the flat end 261 is provided with a second connection hole. A bolt is provided between the first connection hole 223 and the second connection hole, and the connection ear is connected to the flat end 261 on the corresponding side through the bolt.

[0032] Through the implementation of the above vehicle steering device embodiment, the flat structure of the flat ear 222 and the flat end 261 is used to provide a larger contact area for the connection point of the transmission screw 22 and the steering tie rod 26, so as to enhance the stability of the connection between the end of the transmission screw 22 and the steering tie rod 26, reduce the looseness caused by vibration or impact, so that it can maintain high reliability during the long-term use of the vehicle, and reduce the failure caused by connection problems. At the same time, the connection ear is connected to the flat end 261 on the corresponding side by bolts. When the steering tie rod 26 or the transmission screw 22 needs to be replaced, the flat ear 222 and the flat end 261 can simplify the disassembly and installation process, thereby improving the convenience of maintenance.

[0033] Specifically, when the vehicle needs to turn, the vehicle steering device of the embodiment of the present invention is operated by the driver to turn the steering wheel 11, driving the transmission shaft 24 to rotate, and the power is transmitted to the first cylindrical gear 21. The first cylindrical gear 21 is meshed with the face gear 23 for transmission, driving the face gear 23 to rotate. At the same time, due to the transmission characteristics of the face gear 23, the rotation direction of the power is changed by 90 degrees. And by using the threaded pairing of the face gear 23 and the transmission screw 22, the rotation of the face gear 23 converts the rotating power into the linear motion of the transmission screw 22 along its axial direction, so that the transmission screw 22 moves laterally, thereby pulling the two steering rods 26 connected at both ends to move laterally. The other ends of the two steering rods 26 are respectively connected to the steering knuckles of the left and right wheels 12, so that the lateral movement of the steering rods 26 will cause the wheels 12 to deflect, thereby realizing the turning of the vehicle. In addition, the torque of the driver turning the steering wheel 11 is multiplied, so the driver can turn the steering wheel 11 more easily and reduce fatigue.

[0034] The present invention also discloses a power assist system, such as Figure 1 As shown, the vehicle steering device includes the above-mentioned vehicle steering device, as well as a controller 3, an angle sensor 4, a power motor 5 and a second cylindrical gear 6 arranged on the vehicle body. The angle sensor 4 is used to sense the rotation angle of the steering wheel 11, and the controller 3 is electrically connected to the angle sensor 4 and the power motor 5 respectively. The second cylindrical gear 6 is arranged on the output end of the power motor 5, and the second cylindrical gear 6 is meshed and connected with the first cylindrical gear 21.

[0035] Through the implementation of the above-mentioned power-assisting system embodiment, the angle sensor 4 is installed in a fixed position and can sense the rotation angle of the steering wheel 11. When the driver turns the steering wheel 11, the angle sensor 4 obtains the rotation angle of the steering wheel 11 in real time. Then the angle sensor 4 transmits the obtained angle signal to the controller 3, and the controller 3 processes and calculates the angle signal, and sends a control signal to the power-assisting motor 5 according to the control logic set in advance, so as to control the rotation speed and torque of the power-assisting motor 5. The power-assisting motor 5 starts to drive the second cylindrical gear 6 to rotate, and then the second cylindrical gear 6 can drive the first cylindrical gear 21 to rotate. Through the superposition of the driving force of the second cylindrical gear 6, the power of the driver to turn the steering wheel 11 is transmitted to the face gear 23 with the larger superimposed power, thereby achieving a power-assisting effect. And the magnitude of the power-assisting can be achieved by adjusting the output power of the power-assisting motor 5, so that the driver can obtain different steering experiences. In addition, the second cylindrical gear 6 and the face gear 23 are distributed on the opposite sides of the first cylindrical gear 21, that is, the second cylindrical gear 6 and the face gear 23 form a clamping structure for the first cylindrical gear 21, so that the radial force of the gear pair formed by the first cylindrical gear 21 and the second cylindrical gear 6 can be offset by the radial force of the gear pair formed by the face gear 23 and the first cylindrical gear 21 by meshing the first cylindrical gear 21 and the second cylindrical gear 6, thereby greatly reducing the installation cost and difficulty of the gears.

[0036] Furthermore, combined with Figure 4 As shown, a transmission shaft 24 is arranged between the steering wheel 11 and the first cylindrical gear 21, and the power-assist system further comprises a toothed disc 7 arranged on the transmission shaft 24. The toothed disc 7 comprises a disc body 71, and a plurality of disc teeth 72 distributed along the circumferential direction on the outer ring wall of the disc body 71. The angle sensor 4 comprises a light source arranged on one side of the disc teeth 72, and a photosensitive receiver arranged on the other side of the disc teeth 72, and the position of the photosensitive receiver corresponds to that of the light source.

[0037] Through the implementation of the above-mentioned power-assisting system embodiment, the transmission shaft 24 is used to connect the steering wheel 11 and the first cylindrical gear 21, and the toothed disc 7 is set on the transmission shaft 24, so that the toothed disc 7 can synchronize the rotation angle of the steering wheel 11. Since the installation position of the angle sensor 4 is fixed, the structure of the angle sensor 4 is used to detect the shadow change of the light source irradiated on the disc teeth 72 through the photosensitive receiver, and the rotation angle of the disc teeth 72 can be accurately measured, so that the rotation angle of the toothed disc 7 can be obtained in real time, and then the rotation angle of the steering wheel 11 can be obtained, so as to achieve high-precision angle measurement. At the same time, since the disc teeth 72 are evenly distributed along the circumferential direction of the disc body 71, the angle sensor 4 can capture the precise position change of each disc tooth 72 when it passes, which greatly improves the measurement accuracy.

[0038] The present invention also discloses a power steering control method, which adopts the above-mentioned power steering system. The power steering control method includes: When the vehicle turns, the driver turns the steering wheel 11 to drive the first cylindrical gear 21 to rotate, and the face gear 23 cooperates with the first cylindrical gear 21 to reduce speed, and drives the transmission screw 22 to move laterally, so as to pull the wheels 12 on both sides to deflect and realize turning; In response to the rotation of the steering wheel 11, the angle sensor 4 synchronously obtains the rotation angle signal of the steering wheel 11 and transmits it to the controller 3; According to the received rotation angle signal, the controller 3 controls whether to start the power assist motor 5 according to a preset judgment logic; When the controller 3 determines that the received rotation angle signal satisfies the preset judgment logic, no control instruction is output, and the power assist motor 5 remains in the stopped state; When the controller 3 determines that the received rotation angle signal does not satisfy the preset judgment logic, it outputs a control instruction to control the power-assisting motor 5 to start, and drives the second cylindrical gear 6 to drive the first cylindrical gear 21 to rotate to perform steering assistance.

[0039] Through the implementation of the above-mentioned power steering control method embodiment, the angle sensor 4 is used to detect the rotation angle of the steering wheel 11, and the controller 3 performs accurate calculations, and the first cylindrical gear 21, the second cylindrical gear 6, the face gear 23 and the transmission screw 22 perform accurate power transmission, thereby improving the steering accuracy and reducing the difficulty of operation. Among them, the preset judgment logic preferably sets an angle threshold. When the rotation angle of the steering wheel 11 exceeds this threshold, it indicates that the driver does not need to perform steering assistance, and the controller 3 will not start the power motor 5. If the actual rotation angle is less than or equal to this threshold, it indicates that the driver needs to perform steering assistance, and the controller 3 controls the power motor 5 to start.

[0040] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A vehicle steering device, characterized in that: The vehicle steering device includes a vehicle unit and a steering transmission unit, the vehicle unit includes a steering wheel and wheels arranged on a vehicle body, the steering transmission unit includes a first cylindrical gear, a transmission screw and a face gear, the first cylindrical gear is connected to the steering wheel so that the first cylindrical gear and the steering wheel rotate synchronously, the transmission screw is perpendicular to the axial direction of the first cylindrical gear, and the wheels are respectively arranged at both ends of the transmission screw, the face gear is fixedly arranged on the vehicle body, and the face gear is cooperated with the transmission screw to form a screw pair, and the first cylindrical gear is meshed with the face gear.

2. The vehicle steering device according to claim 1, characterized in that: The steering transmission unit further comprises a transmission shaft, one end of which is connected to the middle of the steering wheel, and the first cylindrical gear is arranged on the other end of the transmission shaft.

3. The vehicle steering device according to claim 1, characterized in that: The face gear includes a wheel body and gear teeth. The cross-section of the wheel body is a "T"-shaped structure, including a first wheel portion and a second wheel portion. The outer diameter of the first wheel portion is larger than the outer diameter of the second wheel portion. The gear teeth are arranged on the end face of the first wheel portion away from the second wheel portion, and the gear teeth are arranged along the outer edge of the end face of the first wheel portion. An assembly hole that passes through the first wheel portion and the second wheel portion is also provided in the middle portion of the wheel body. An internal thread is provided in the assembly hole, and an external thread that cooperates with the internal thread for transmission is provided on the outer wall of the transmission screw.

4. The vehicle steering device according to claim 3, characterized in that: The steering transmission unit further comprises a bearing seat arranged on the vehicle body, and the second wheel portion is rotatably connected to the bearing seat.

5. The vehicle steering device according to claim 4, characterized in that: The bearing seat includes a base plate arranged on the vehicle body, and a positioning plate arranged on the base plate, the plate surface of the base plate is parallel to the transmission screw, the positioning plate is perpendicular to the plate surface of the base plate, and a positioning hole is opened on the positioning plate, a bearing is arranged on the outer wall of the second wheel part, and the second wheel part is rotatably connected in the positioning hole through the bearing.

6. The vehicle steering device according to claim 1, characterized in that: The steering transmission unit further comprises steering tie rods arranged at both ends of the transmission screw, and the ends of the transmission screw are connected to the steering knuckles of the wheels through the steering tie rods on the corresponding sides.

7. The vehicle steering device according to claim 6, characterized in that: The end of the transmission screw is provided with flat ears arranged opposite to each other, and the flat ears are provided with a first connecting hole. The end of the steering rod away from the wheel is provided with a flat end head which fits and is inserted between the two flat ears, and the flat end head is provided with a second connecting hole. A bolt is provided between the first connecting hole and the second connecting hole, and the connecting ear is connected to the flat end head on the corresponding side through the bolt.

8. A power assist system, characterized in that: The vehicle steering device comprises the vehicle steering device as described in any one of claims 1 to 7, and a controller, an angle sensor, a power-assist motor and a second cylindrical gear arranged on a vehicle body, wherein the angle sensor is used to sense the rotation angle of the steering wheel, and the controller is electrically connected to the angle sensor and the power-assist motor respectively, and the second cylindrical gear is arranged on the output end of the power-assist motor, and the second cylindrical gear is meshingly connected to the first cylindrical gear.

9. The power assist system according to claim 8, characterized in that: A transmission shaft is arranged between the steering wheel and the first cylindrical gear. The power-assisting system also includes a toothed disk arranged on the transmission shaft. The toothed disk includes a disk body and a plurality of disk teeth distributed on the outer ring wall of the disk body along the circumferential direction. The angle sensor includes a light source arranged on one side of the disk teeth and a photosensitive receiver arranged on the other side of the disk teeth. The photosensitive receiver corresponds to the position of the light source.

10. A power steering control method, characterized in that: Using the power steering system according to any one of claims 8 to 9, the power steering control method comprises: When the vehicle turns, the driver turns the steering wheel to drive the first cylindrical gear to rotate, and the face gear cooperates with the first cylindrical gear to reduce speed, and drives the transmission screw to move laterally, so as to pull the wheels on both sides to deflect and realize turning; In response to the rotation of the steering wheel, the angle sensor synchronously acquires a rotation angle signal of the steering wheel and transmits the signal to the controller; According to the received rotation angle signal, the controller controls whether to start the power assist motor according to a preset judgment logic; When the controller determines that the received rotation angle signal satisfies the preset judgment logic, no control instruction is output, and the power assist motor remains in a stopped state; When the controller determines that the received rotation angle signal does not satisfy the preset judgment logic, it outputs a control instruction to control the power-assisting motor to start, and drives the second cylindrical gear to drive the first cylindrical gear to rotate to assist steering.

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