Rear wheel steering system

Abstract

The utility model relates to the technical field of automobile steering, in particular to a rear wheel steering system which comprises a parallel shaft steering assembly and a coaxial steering assembly which are used for controlling the rotation angle of a tire, the parallel shaft steering assembly and the coaxial steering assembly respectively comprise a shell, a movable end and a fixed end, and the movable end and the fixed end are arranged at the two ends of the shell respectively. The fixed end is fixedly connected with one end of the shell, the movable end is installed on a rear wheel steering knuckle, the parallel shaft steering assembly further comprises a first pushing assembly, the coaxial steering assembly further comprises a second pushing assembly, and the first pushing assembly and the second pushing assembly are both used for driving the movable end to do linear motion so as to adjust the steering angle of the rear wheel. According to the utility model, the two steering motors can be respectively controlled to realize independent operation of tires, so that the function of stabilizing a vehicle body under different road conditions is achieved, the risk of drifting or out-of-control of the vehicle is reduced, the vehicle can be more easily subjected to accurate direction adjustment during high-speed driving, and the maneuverability and responsiveness of the vehicle are improved.

Description

Technical Field

[0001] This utility model relates to the field of automotive steering technology, and in particular to a rear-wheel steering system. Background Technology

[0002] When a vehicle is cornering, changes in wheel contact area and wheel alignment alter its steering characteristics. Rear-wheel steering technology compensates for the inherent limitations of vehicle steering mechanisms caused by the use of pneumatic rubber tires. At high speeds, braking one or more wheels helps maintain vehicle stability.

[0003] Currently, the main type of rear-wheel steering is integrated, which uses a through-type structure to make the rear wheels rotate synchronously. However, it cannot achieve the effect of controlling the two rear wheels separately. At the same time, the intermediate transition part of the integrated structure is too long, resulting in a large overall weight and high space requirements, which is a disadvantage in terms of the spatial arrangement of vehicle parts. Utility Model Content

[0004] In order to overcome the shortcomings of the prior art, this utility model provides a rear wheel steering system, which solves the problem that the prior art cannot achieve the effect of separate control of the two rear wheels when the rear wheels rotate synchronously.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0006] The rear wheel steering system includes a parallel-axis steering assembly and a coaxial steering assembly for controlling the tire rotation angle. Both the parallel-axis steering assembly and the coaxial steering assembly include a housing, a movable end, and a fixed end. The movable end and the fixed end are respectively disposed at both ends of the housing. The fixed end is fixedly connected to one end of the housing. The movable end is mounted on the rear wheel steering knuckle. The parallel-axis steering assembly also includes a first push assembly, and the coaxial steering assembly also includes a second push assembly. Both the first push assembly and the second push assembly are used to drive the movable end to make linear motion to adjust the rear wheel steering angle.

[0007] Furthermore, the first driving component includes a first synchronous motor fixedly mounted on the housing, a synchronous toothed belt driven on the output shaft of the first synchronous motor via a small synchronous pulley, and a ball screw driven at the bottom of the synchronous toothed belt via a large synchronous pulley. The large synchronous pulley is rotatably connected to the housing via a bearing.

[0008] Furthermore, a retaining ring fixed to the housing is rotatably mounted on the ball screw, one end of the ball screw is provided with a sliding screw that slides with the housing, and the other end of the ball screw is fixedly connected to the movable end by a locking nut. A position sensor matching one end of the sliding screw is fixed on one side of the housing.

[0009] Furthermore, the second pushing component also includes a second synchronous motor fixedly installed inside the housing. A locking clutch that is connected to the housing is mounted on the output shaft of the second synchronous motor. A planetary reducer is connected to the locking clutch, and a threaded screw is fixed at the shaft of the planetary reducer.

[0010] Furthermore, a threaded sleeve is threadedly connected to the threaded screw, one end of which is fixedly connected to the movable end. The threaded sleeve and the housing can only slide and cannot rotate. A position sensor two that matches the threaded sleeve is also provided on one side of the housing.

[0011] Furthermore, rubber bushings are provided on both the movable end and the fixed end.

[0012] By employing the above technical solution, this utility model provides a rear-wheel steering system, which, compared to the prior art, has at least the following beneficial effects:

[0013] 1. By setting up a parallel axis steering assembly and a coaxial steering assembly, this utility model can achieve independent operation of the tires by separately controlling the two steering motors, thereby achieving vehicle stability under different road conditions, reducing the risk of vehicle fishtailing or loss of control, making it easier for the vehicle to make precise directional adjustments at high speeds, and improving the vehicle's maneuverability and responsiveness; moreover, the internal structure is compact, requires little installation space, and is lightweight.

[0014] 2. This utility model makes the vehicle more stable when turning by actively adjusting the angle of the rear wheels, reducing body roll and excessive tilt, and improving passenger comfort. At the same time, the rear wheels cooperate with the front wheels to make the driver feel a more natural and smooth steering feedback, which is especially noticeable when turning at high speed or in emergency situations. Furthermore, the active steering of the rear wheels helps the vehicle maintain the lane and target driving trajectory more accurately, reducing the driver's operating burden.

[0015] 3. When changing lanes at high speeds, this utility model maintains the same direction as the front wheels by changing the angle of the rear wheels, creating an effect of increased wheelbase and making the vehicle more agile and stable at high speeds. Equipped with a rear-wheel steering system, the turning radius is smaller than that of comparable models, and the active rear-wheel steering system ensures that the rear wheels and front wheels move in the same direction when changing lanes, allowing for faster and more stable lane changes. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 This is a schematic diagram of the parallel shaft steering assembly of this utility model;

[0018] Figure 2 This is a front sectional view of the parallel shaft steering assembly of this utility model;

[0019] Figure 3 This is a schematic diagram of the coaxial steering assembly of this utility model;

[0020] Figure 4 This is a front sectional view of the coaxial steering assembly of this utility model.

[0021] In the picture:

[0022] 10. Parallel shaft steering assembly;

[0023] 20. Coaxial steering assembly;

[0024] 30. Housing; 40. Movable end; 50. Fixed end; 60. Rubber bushing;

[0025] 11. Drive assembly 1; 111. Synchronous motor 1; 112. Synchronous toothed belt; 113. Ball screw; 114. Anti-reverse retaining ring 1; 115. Sliding screw; 116. Position sensor 1;

[0026] 21. Drive assembly two; 211. Synchronous motor two; 212. Lock-up clutch; 213. Planetary reducer; 214. Threaded screw; 215. Threaded sleeve. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Example 1

[0029] When a vehicle is traveling at low speeds, oversteer can be appropriately increased by the rear wheels turning in the opposite direction to the front wheels. When a vehicle traveling at high speed encounters an emergency lane change, it is prone to oversteer. A small but important steering input from the rear wheels in the same direction as the front wheels can compensate for this tendency. Therefore, an auxiliary steering system is usually installed on the rear wheels to give the car better balance.

[0030] To allow for individual control of the two rear wheels and enhance vehicle stability, such as Figures 1-2As shown, a rear wheel steering system is provided, including a parallel shaft steering assembly 10 for controlling the rotation angle of the tires. The parallel shaft steering assembly 10 includes a housing 30, a movable end 40, a fixed end 50, and a push assembly 11. The movable end 40 and the fixed end 50 are respectively disposed at both ends of the housing 30. The fixed end 50 is fixedly connected to one end of the housing 30, and the movable end 40 is mounted on the rear wheel steering knuckle.

[0031] The push assembly 11 is used to drive the movable end 40 to make linear motion to adjust the steering angle of the rear wheel. The push assembly 11 includes a synchronous motor 111 fixedly mounted on the housing 30. The synchronous motor 111 is a three-phase permanent magnet synchronous motor. The control part uses PWM to adjust the input voltage of the synchronous motor 111, thereby controlling the rotation speed of the synchronous motor 111. The synchronous toothed belt 112 is set on the output shaft of the synchronous motor 111 through a small synchronous pulley. The synchronous toothed belt 112 is a speed reduction and torque increase structure. The transmission ratio is based on the diameter ratio of the large pulley D and the small pulley d. I = D / dI is the transmission ratio. At the same time, the synchronous toothed belt 112 has the characteristics of high transmission efficiency, convenient installation and low noise. During operation, the synchronous toothed belt 112 is not easy to slip and will not cause output loss of the synchronous motor 111.

[0032] The ball screw 113, driven by a large synchronous pulley and mounted at the bottom of the synchronous toothed belt 112, uses a deep groove ball bearing at its fixed end 50 as an auxiliary rotation and friction-reducing structure. The ball screw 113 is secured by an interference fit between the deep groove ball bearing and the ball screw 113 sleeve, along with a lock nut. On the other side, a deep groove ball bearing is also interference-fitted with the end cover of the housing 30, ensuring the ball screw 113 sleeve and end cover maintain rotational freedom but not sliding freedom. The large synchronous pulley is rotatably connected to the housing 30 via a self-lubricating bearing, which features small clearance, good wear resistance, and stable function. Both ends are supported by self-lubricating bearings, ensuring the coaxiality of the spindle during movement and preventing jamming or resistance caused by spindle misalignment. Regarding the force issue, the self-lubricating bearing serves as an auxiliary support for linear motion, minimizing friction and clearance while achieving linear motion, thus ensuring smoother overall operation. The synchronous motor 111 is parallel to the ball screw 113, and transmits power to the rear wheel through the synchronous toothed belt 112. The ball screw 113 is rotatably equipped with a backstop ring 114 fixed to the housing 30. One end of the ball screw 113 is equipped with a sliding screw 115 that slides with the housing 30, and the other end of the ball screw 113 is fixedly connected to the movable end 40 through a locking nut. A position sensor 116 matching one end of the sliding screw 115 is fixed on one side of the housing 30. The position sensor 116 serves as a position control feedback signal. After the initial position is calibrated, the change in position during the movement is used as the signal output.

[0033] By starting the synchronous motor 111, the output shaft of the synchronous motor 111 rotates, which drives the ball screw 113 to rotate through the synchronous toothed belt 112. This converts the rotational motion of the synchronous motor 111 into linear motion, which drives the sliding screw 115 to move in the housing 30. In turn, the extension and retraction of the ball screw 113 pushes the movable end 40 to move, and the movable end 40 pushes the rear wheel to rotate. After the rear wheel is subjected to force and rotates, the displacement signal is fed back by the position sensor 116 to control the tire rotation angle.

[0034] Example 2

[0035] like Figures 3-4 As shown, a coaxial steering assembly 20 for controlling the tire rotation angle is also provided. The coaxial steering assembly 20 includes a housing 30, a movable end 40, a fixed end 50, and a push assembly 21. The movable end 40 and the fixed end 50 are respectively disposed at both ends of the housing 30. The fixed end 50 is fixedly connected to one end of the housing 30, and the movable end 40 is mounted on the rear wheel steering knuckle.

[0036] The second push assembly 21 is used to drive the movable end 40 to make linear motion to adjust the rear wheel steering angle. The second push assembly 21 also includes a second synchronous motor 211 fixedly installed inside the housing 30. The second synchronous motor 211 is a permanent magnet three-phase synchronous motor. The control part uses PWM to adjust the input voltage of the second synchronous motor 211, thereby controlling the rotation speed of the second synchronous motor 211. A locking nut is used as a structure to fix the second synchronous motor 211 to the housing 30, ensuring a rigid connection between the second synchronous motor 211 and the housing 30. When the output shaft of the second synchronous motor 211 rotates, it will not rotate relative to the housing 30. A locking clutch 212 is installed on the output shaft of the second synchronous motor 211 and is connected to the housing 30. A planetary reducer 213 is connected to the locking clutch 212. The planetary reducer 213 serves as a speed reduction and torque amplification structure. The planetary reducer 213 is small in size, light in weight, and has a high load-bearing capacity. It has a long service life, stable operation, and low noise. The planetary reducer 213 has a threaded screw 214 fixed at its shaft. A threaded sleeve 215 is threadedly connected to the threaded screw 214. One end of the threaded sleeve 215 is fixedly connected to the movable end 40. The synchronous motor 211 is on the same axis as the threaded screw 214. The threaded screw 214 is used as the force and displacement transmission element. A lock-up clutch 212 is used as the stop element to prevent the threaded screw 214 from retracting. The planetary reducer 213 is used as the speed reduction and torque amplification structure. The threaded sleeve 215 can only slide and cannot rotate with the housing 30. A position sensor 2 matching the threaded sleeve 215 is also set on one side of the housing 30. The position sensor 2 can determine the displacement of the rear wheel steering system connection end and convert it into the tire deflection angle through the ECU. This accurately controls different working conditions during the vehicle's driving process, reduces the impact of road surface and driving speed, and improves handling stability.

[0037] When the second synchronous motor 211 is running, the rotating shaft of the second synchronous motor 211 drives the locking clutch 212 to rotate. The second synchronous motor 211 drives the planetary reduction system to rotate. The planetary reduction system drives the threaded screw 214 to rotate. The threaded screw 214 drives the threaded sleeve 215 to move linearly inside the housing 30, pushing the movable end 40 to move and realize the telescopic function. The movable end 40 pushes the rear wheel to rotate, and the rear wheel rotates under force. In conjunction with the position sensor 2 to feed back the displacement signal, the tire rotation angle is controlled.

[0038] Rubber bushings 60 are installed on both the movable end 40 and the fixed end 50. The rubber bushings 60 serve as a buffer structure at the connection between the movable end 40 and the fixed end 50 to reduce the impact of tires on the steering structure during driving, reduce the vibration of the rear wheel steering structure during vehicle operation, and prevent resonance. The rubber bushings 60 also ensure that the deflection of the connecting shaft during tire steering will not cause a large lateral force on the spindle and housing 30. At the same time, the rubber bushings 60 also have the function of reducing abnormal noise, reducing operating noise, and improving the overall NVH performance.

[0039] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0040] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rear wheel steering system, characterized by: Parallel shaft steering assembly (10) and coaxial steering assembly (20) for controlling the rotation angle of the tire are included; Parallel shaft steering assembly (10) and coaxial steering assembly (20) both include a housing (30), a movable end (40) and a fixed end (50), the movable end (40) and the fixed end (50) are respectively arranged at both ends of the housing (30), the fixed end (50) is fixedly connected with one end of the housing (30), the movable end (40) is installed on the rear wheel steering knuckle, the parallel shaft steering assembly (10) further includes a pushing assembly one (11), the coaxial steering assembly (20) further includes a pushing assembly two (21), the pushing assembly one (11) and the pushing assembly two (21) are both used for driving the movable end (40) to make linear motion to adjust the rear wheel steering angle.

2. The rear wheel steering system of claim 1, wherein: The pushing assembly one (11) includes a synchronous motor one (111) fixedly installed on the housing (30), a synchronous toothed belt (112) arranged on the output shaft of the synchronous motor one (111) through a small synchronous wheel transmission, and a ball screw (113) arranged at the bottom of the synchronous toothed belt (112) through a large synchronous wheel transmission, the large synchronous wheel is rotatably connected with the housing (30) through a bearing.

3. The rear wheel steering system of claim 2, wherein: The ball screw (113) is rotatably provided with a retreat stop ring one (114) fixed with the housing (30), one end of the ball screw (113) is provided with a sliding screw (115) sliding with the housing (30), the other end of the ball screw (113) is fixedly connected with the movable end (40) through a locking nut, and one side of the housing (30) is fixedly provided with a position sensor one (116) matched with one end of the sliding screw (115).

4. The rear wheel steering system of claim 1, wherein: The pushing assembly two (21) further includes a synchronous motor two (211) fixedly arranged in the inner side of the housing (30), a lock clutch (212) drivingly connected with the housing (30) is installed on the output shaft of the synchronous motor two (211), a planetary reducer (213) is drivingly connected on the lock clutch (212), and a threaded screw rod (214) is fixedly arranged at the axis of the planetary reducer (213).

5. The rear wheel steering system of claim 4, wherein: The threaded screw rod (214) is threadedly connected with a threaded sleeve (215), one end of the threaded sleeve (215) is fixedly connected with the movable end (40), the threaded sleeve (215) can only slide with the housing (30) and cannot rotate, and the side of the housing (30) is also provided with a position sensor two matched with the threaded sleeve (215).

6. The rear wheel steering system of claim 1, wherein: The movable end (40) and the fixed end (50) are both provided with rubber bushings (60).

Images