Steering actuator for increasing steering speed

Abstract

The utility model relates to a steering gear, in particular to a steering actuator for increasing the steering speed. The steering gear comprises a shell, a rack, a ball head pull rod and steering execution mechanisms, the two ends of the shell are respectively provided with the steering execution mechanisms, and each steering execution mechanism comprises a main controller, a driving motor, a worm and worm wheel and a gear shaft. A steering wheel of the steering actuator is decoupled from a steering gear, steering can be faster, in-situ full-angle steering only needs one second, and the steering actuator can rapidly turn around in situ; meanwhile, faster steering can be achieved without being limited by rotation of a steering wheel, and therefore the requirement for the steering speed can be met. The problems that an existing steering gear is low in steering speed and cannot meet the automatic driving requirement are solved.

Description

Technical Field

[0001] The utility model relates to a steering actuator, in particular to a steering actuator for enhancing the steering speed. Background Art

[0002] Traditional steering gears (steering actuators) include a housing, an input shaft, a rack, and a ball joint rod. The top end of the input shaft is connected to the steering wheel through an intermediate shaft and a steering column; the bottom end of the input shaft is connected to a gear shaft through a torsion bar, and the gear shaft meshes with the rack. The steering wheel can drive the rack to move axially through the steering column, the intermediate shaft, the input shaft, the torsion bar, and the gear shaft in sequence, thereby pulling the ball joint rod to move, and then pulling the wheel connected to the ball joint rod to deflect, completing the steering. Due to the large friction between the tire and the ground, it is difficult to turn the steering wheel. Generally, an electric motor or hydraulic power assistance is required to reduce the steering resistance and improve the driving feel. During the steering process, it is necessary to detect the rotation angle of the gear shaft to feedback and adjust the power assistance motor to ensure the accuracy of steering. Currently, the detection of the gear shaft is to detect the torque angle between the torsion bar for the gear shaft and the input shaft through a torque angle signal sensor, and then indirectly detect the rotation of the gear shaft (see Figure 3 ).

[0003] The above traditional steering gear also has the following defects: Since the steering wheel is connected to the gear shaft through the steering column, the intermediate shaft, the input shaft, and the torsion bar in sequence, the steering wheel and the gear shaft are in a strong connection state, resulting in that the gear shaft can only rotate when the steering wheel rotates; Since the rotation of the steering wheel is easily interfered manually by the driver and affected by the driver's reaction speed, the rotation speed of the steering wheel is slow, and the rotation speed of the steering wheel will affect the rotation speed of the gear shaft, resulting in that the gear shaft cannot rotate quickly, greatly affecting the transmission between the steering wheel and the gear shaft, thus affecting the steering speed and making it difficult to meet the requirements of autonomous driving or assisted driving above L3 level for the steering speed.

[0004] In addition, in the prior art, connecting teeth are respectively arranged at both ends of the rack. The connecting teeth at one end of the rack are connected to the gear shaft of the motor-assisted steering power, and the connecting teeth at the other end of the rack are connected to the gear shaft of the mechanical power assist. The gear shaft of the mechanical power assist is connected to the steering wheel through a torsion bar, an input shaft, an intermediate shaft and a steering column. For example, a dual-input shaft electric power steering gear and an automobile disclosed in a patent application with the publication number CN209650364U can accelerate the steering speed through multiple power assists. However, since one end of the rack is mechanically assisted and the other end is motor-assisted, the acting forces of the mechanical assist and the motor assist on the rack are not exactly the same, which will cause the rack to be unbalanced in force. The solution is to change the phase angle of the connecting teeth at both ends of the rack, change the forces at both ends of the rack, and make a part of the circumferential forces at both ends of the rack cancel each other out, thereby reducing the flipping of the rack and making it difficult for the circumferential force to affect the movement of the rack. However, the circumferential forces at both ends of the rack cannot be completely cancelled out, and they will still affect the movement speed of the rack.

[0005] Therefore, it is necessary to design a steering actuator that enhances the steering speed to solve the above problems. Summary of the Invention

[0006] The purpose of the present utility model is to provide a steering actuator with enhanced steering speed that can steer flexibly and quickly in view of the deficiencies of the prior art.

[0007] The technical solution of the present utility model is as follows:

[0008] A steering actuator with enhanced steering speed, which includes a housing, a rack, a ball joint rod and a steering actuator mechanism. The rack is installed on the housing through a support seat, and ball joint rods are respectively arranged at both ends of the rack. It is characterized in that: steering actuator mechanisms are respectively arranged at both ends of the housing. The steering actuator mechanism includes a main controller, a driving motor, a worm and worm gear and a gear shaft connected to the steering wheel control center line. The driving motor is electrically connected to the main controller, the output shaft of the driving motor is connected to the gear shaft through a worm and worm gear, and the gear shaft meshes with the rack.

[0009] A single-axis angle signal sensor for detecting the rotation angle of the gear shaft is respectively arranged on the gear shaft, and the single-axis angle signal sensor is electrically connected to the main controller.

[0010] Preferably, the main controller is connected to the steering wheel control center through a CAN bus.

[0011] The contact angle between the rack and the support seat is 15°-33°.

[0012] Preferably, the contact angle between the rack and the support seat is 30°.

[0013] One end of the described rack is provided with connecting teeth A, and the other end of the rack is provided with connecting teeth B. The connecting teeth A and the connecting teeth B are respectively connected to the gear shafts at both ends of the housing; the phase angles of the connecting teeth A and the connecting teeth B are the same.

[0014] The beneficial effects of the present utility model are as follows:

[0015] The steering actuator steering wheel for enhancing the steering speed is decoupled from the steering gear, and can achieve a flexible transmission ratio. The steering wheel angle can achieve a 150° rotation to complete a full turn, enabling the driver not to cross hands when turning the vehicle full circle, making parking more convenient, and the steering wheel rotates more quickly; since the steering wheel rotation angle is reduced, and the drive motor can rotate faster without limitation, it can turn faster, and it only takes 1 s to turn full angle in place, enabling a quick U-turn in place; at the same time, the steering wheel is decoupled from the steering gear, and the operation of the steering gear is not restricted by the rotation of the steering wheel, and it can turn faster, thus meeting the requirements for steering speed in autonomous driving or assisted driving above level L3. In addition, multiple steering actuating mechanisms are used for steering and power steering. The torque can be evenly distributed through multiple steering actuating mechanisms, and the torque borne by a single steering actuating mechanism can be effectively reduced while ensuring a large output of the total torque, thereby effectively reducing the size of a single steering actuating mechanism; at the same time, the intermediate shaft, the input shaft and the torsion bar are cancelled, decoupling the steering gear from the steering wheel, further reducing the occupation of the space in the engine compartment, and making the layout of the engine compartment and the chassis more flexible. It solves the problems of slow steering speed of the existing steering gear and difficulty in meeting the requirements of autonomous driving. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the present utility model;

[0017] Figure 2 is a schematic installation diagram of the single-axis angle signal sensor of the present utility model;

[0018] Figure 3 is a schematic layout diagram of the sensor in the prior art;

[0019] Figure 4 is a schematic diagram of the contact angle (15°) of the present utility model;

[0020] Figure 5 is a schematic diagram of the contact angle (30°) of the present utility model;

[0021] Figure 6 is a schematic diagram of the contact angle (33°) of the present utility model;

[0022] Figure 7 is a schematic structural diagram of the rack in the prior art;

[0023] Figure 8 is a schematic structural diagram of the rack of the present utility model;

[0024] Figure 9 is the statistical chart of the wear amount of the present utility model;

[0025] Figure 10 is the statistical chart of the force on the rack of the present utility model;

[0026] Figure 11 is the statistical chart of the force on the rack in the prior art.

[0027] In the figure: 1. housing, 2. rack, 3. ball-end pull rod, 4. support seat, 5. main controller, 6. drive motor, 7. gear shaft, 8. single-axis angle signal sensor, 9. connecting tooth A, 10. connecting tooth B, 11. input shaft, 12. torsion bar, 13. torque angle signal sensor, 14. worm gear, 15. worm. Specific embodiments

[0028] The steering actuator for enhancing the steering speed includes a housing 1, a rack 2, a ball-end pull rod 3 and a steering execution mechanism. The rack 2 is inserted into the housing 1, and both ends of the rack 2 are respectively supported by support seats 4 provided on the housing 1. Ball-end pull rods 3 are respectively arranged at both ends of the rack 2, and the ball-end pull rods 3 are connected to the wheels. Steering execution mechanisms are respectively arranged at both ends of the housing 1. Since when a single power assist mechanism is driving, in order to ensure durability, it is necessary to increase the force-bearing area, thereby reducing the pressure; the rack 2 is driven in cooperation by the steering execution mechanisms arranged at both ends of the housing 1, and the torque required to drive the rack 2 is shared by multiple steering execution mechanisms, and then the pressure is reduced by reducing the torque, and the torque required to be provided by a single steering execution mechanism is reduced, so that the volume occupied by a single steering execution mechanism can be effectively reduced.

[0029] The steering execution mechanism includes a main controller 5, a drive motor 6, a worm gear and a gear shaft 7. The drive motor 6 is electrically connected to the main controller 5 to control the start, stop and rotation of the drive motor 6 through the main controller 5, wherein the rotation of the drive motor 6 includes the rotation angle, rotation torque and rotation speed of the output shaft of the drive motor 6. A worm 15 is connected to the output shaft of the drive motor 6, a worm gear 14 is connected to the worm 15, a gear shaft 7 is inserted into the center of the end face of the worm gear 14, and the gear shaft 7 meshes with the rack 2. The function of the worm 15 is to drive the worm gear 14 to rotate through the rotating worm 15 during the rotation of the drive motor 6 driving the worm 15, and then drive the gear shaft 7 to rotate through the rotating worm gear 14, and thus drive the rack 2 to move through the rotating gear shaft 7.

[0030] The main controller 5 is connected to the steering wheel control center line. The steering wheel control center can detect the rotation of the steering wheel. It converts the rotation signal of the steering wheel into a digital signal and transmits it to the main controller 5. The main controller 5 controls the rotation of the drive motor 6 according to the rotation signal of the steering wheel, so as to perform steering. Since the steering wheel is connected to the steering gear by a line, it can decouple the steering wheel from the steering gear, and then the intermediate shaft between the steering wheel and the steering gear can be discarded, further reducing the space occupation and enabling flexible arrangement of the engine compartment and the chassis. During the driving of the vehicle, the drive motor 6 can also detect the reaction force transmitted to the drive motor 6 from the road surface through the wheels, ball joint tie rod 3, rack 2, gear shaft 7, and worm and worm gear in sequence, and then detect the road surface information. The drive motor 6 transmits the road surface signal to the steering wheel control center through the main controller 5, so that the steering wheel control center can control the rotation damping of the steering wheel according to the road surface information, and thus transmit the road feeling information to the driver.

[0031] In the prior art, an output shaft is installed on the gear shaft 7, a torsion bar is arranged between the output shaft and the gear shaft, and a torque angle signal sensor is arranged at the bottom end of the output shaft. The torque angle signal sensor detects the change of the torque between the gear shaft and the output shaft or the change trend by detecting the change of the torque angle, so as to detect the rotation angle of the gear shaft; during the detection process, the cooperation of the output shaft and the torsion bar is required for the torque angle signal sensor to perform the detection (see Figure 3 ).

[0032] In this application, single-axis angle signal sensors 8 (such as HELLA 6PD 312.472-71 type) for detecting the rotation angle of the gear shaft 7 are respectively arranged on the gear shafts 7 at both ends of the housing 1 of the steering actuator. The single-axis angle signal sensors 8 are electrically connected to the main controller 5. The function of the single-axis angle signal sensors 8 is to detect the rotation angle of the gear shaft 7 through the single-axis angle signal sensors 8, and then transmit the rotation angle signal of the gear shaft 7 to the main controller 5, so that the main controller 5 can perform feedback adjustment on the rotation of the gear shaft 7 according to the rotation angle of the gear shaft 7 to ensure that the gear shaft 7 rotates in place, that is, to ensure that the steering is in place. Since the detection is performed by the single-axis angle signal sensors 8, the single-axis angle signal sensors 8 do not require the cooperation of the output shaft and the torsion bar, and can detect the rotation of the gear shaft 7, thus saving the space occupied by the output shaft and the torsion bar.

[0033] Preferably, the main controller 5 is connected to the steering wheel control center through the CAN bus. The CAN bus adopts non-destructive arbitration technology. When two nodes transmit data to the network simultaneously, the node with a lower priority actively stops data transmission, while the node with a higher priority can continue to transmit data without being affected, effectively avoiding bus conflicts. Furthermore, through the CAN bus, the main controllers 5 at both ends of the housing 1 control the drive motors 6 to operate cooperatively, making the rotation of the drive motors 6 less likely to conflict. The CAN bus can transmit and receive data in a one-to-many and broadcast concentration manner, ensuring data transmission among the main controllers 5 at both ends of the housing 1 and the steering wheel control center, ensuring that the steering wheel control center can drive the main controllers 5 at both ends of the housing 1 respectively, and can respectively receive the road feeling information transmitted by the main controllers 5 at both ends of the housing 1.

[0034] The contact angle between the rack 2 and the support seat 4 is 15° - 33°. Preferably, the contact angle between the rack 2 and the support seat 4 is 30°. The larger the contact angle between the rack 2 and the support seat 4, the larger the contact area, which can effectively reduce the pressure, reduce the difference between static and dynamic friction forces, ensure that the difference between static and dynamic friction forces is within 10 N, and reduce the wear amount by 65% (normally, the maximum static friction force is only slightly greater than the dynamic friction force, and the size of the friction force has nothing to do with the contact area. The explanation for reducing the wear amount is directly illustrated by experiments).

[0035] A comparative experiment was conducted with the contact angle less than 15° (such as 13°) and the contact angle of 30° as variables, with other conditions of the experiment being the same. The other conditions of the experiment were that the movement speed of the rack was 10 mm / s, the load applied to the rack was 2000 N, the stroke of the rack was ±72 mm, the number of cycles was 100,000 times, the lubrication condition was grease coating, the maximum operating temperature was 80 °C, and the surface roughness of the rack was Ra0.2. The diameter of the rack was measured before and after the experiment, and the wear amount of the rack was statistically analyzed through the difference in the rack diameter, and a bar chart of the wear amount statistical results was drawn (see Figure 9 )

[0036] It can be easily seen from the bar chart of the wear amount statistical results that the wear amount of the rack is much smaller when the contact angle between the rack and the support seat is 30° than when the contact angle between the rack and the support seat is less than 15°. Therefore, when driving the rack through multiple steering angle actuators, choosing a contact angle of 15° - 33° to support the rack can effectively reduce the wear amount by 65%.

[0037] One end of the rack 2 is provided with a connecting tooth A9, and one end of the rack 2 is provided with a connecting tooth B10. The connecting tooth A9 and the connecting tooth B10 are respectively connected to the gear shafts 7 at both ends of the housing 1; the phase angles of the connecting tooth A9 and the connecting tooth B10 are the same. Since both ends of the rack are assisted by motors and the phase angles of the connecting tooth A9 and the connecting tooth B10 are the same, the force magnitudes at both ends of the rack can be made consistent, so that the circumferential forces at both ends of the rack can be completely offset, making it not easy to affect the movement of the rack.

[0038] Experimental verification:

[0039] Taking the phase angles of the connecting teeth at both ends of the rack as 0° (the phase angles are the same) and 5° (the phase angles are different) as variables, an experiment is carried out with the other conditions of the experiment being the same. The other conditions of the experiment are respectively the rotational speed of the gear shaft of 30 - 45 rpm / min, no load at both ends of the rack, the rack stroke being 90% of the full stroke, and the lubrication method being grease coating. During the experiment, the force and force fluctuation of the rack are statistically analyzed.

[0040] When the phase angle of the connecting teeth at both ends of the rack is 0°, the forces on the rack are: left average torque: 1.264 Nm; right average torque: 1.24 Nm; left fluctuation: 0.3819 Nm; right fluctuation: 0.3640 Nm (see Figure 10 ).

[0041] When the phase angle of the connecting teeth at both ends of the rack is 5°, the forces on the rack are: left average torque: 1.475 Nm; right average torque: 1.437 Nm; left fluctuation: 0.5602 Nm; right fluctuation: 0.5338 Nm (see Figure 11 ).

[0042] It can be easily seen from the comparison of the above data that when the phase angle of the connecting teeth at both ends of the rack is 0°, the force on the rack is significantly better than when the phase angle of the connecting teeth at both ends of the rack is 5°, and both the force and torque fluctuations of the rack are reduced. It is manifested as smoother and faster movement.

[0043] When turning the steering wheel to steer, the steering control center of the steering wheel transmits the steering signals to the main controllers 5 at both ends of the housing 1 respectively. The main controller 5 controls the driving motor 6 to rotate. The driving motor 6 drives the rack 2 to move through the worm and gear, and the gear shaft 7 in sequence. Then the moving rack 5 pulls the wheel to deflect through the ball joint rod 3 to steer. During the steering process, the rotation of the gear shaft 7 is detected by the single-axis angle signal sensor 8, and then the steering is detected. The single-axis angle signal sensor 8 transmits the detection signal to the main controller 5. The main controller 5 performs calculations and controls the driving motor 6 again to form a closed-loop control until the gear shaft 7 rotates to the set angle. Thus, during the rotation of the gear shaft 7, the wheel is pulled to deflect to the set angle through the rack 2 and the ball joint rod 3 in sequence, thereby ensuring the completion of steering.

[0044] The steering actuator steering wheel that enhances the steering speed is decoupled from the steering gear, enabling a flexible transmission ratio. The steering wheel can achieve a full turn with a 150° rotation, allowing the driver to avoid crossing hands when turning the steering wheel full lock, making parking more convenient and the steering wheel turn more quickly. Since the steering angle of the steering wheel is reduced and the drive motor can rotate faster without restriction, the vehicle can turn more quickly, and it only takes 1 s to turn full lock in place, enabling a rapid U-turn. At the same time, the steering wheel is decoupled from the steering gear, and the operation of the steering gear is not restricted by the rotation of the steering wheel, allowing for faster steering, thus meeting the requirements for steering speed in autonomous driving or assisted driving at L3 level and above. Additionally, multiple steering actuators are used for steering and power steering. The torque can be evenly distributed through multiple steering actuators, effectively reducing the torque borne by a single steering actuator while ensuring a large output of the total torque, thereby effectively reducing the size of a single steering actuator. At the same time, the intermediate shaft, input shaft, and torsion bar are eliminated, decoupling the steering gear from the steering wheel, further reducing the space occupied in the engine compartment and making the layout of the engine compartment and chassis more flexible. This solves the problem of slow steering speed of existing steering gears and difficulty in meeting the requirements of autonomous driving.

Claims

1. A steering actuator for enhancing steering speed, comprising a housing (1), a rack (2), a ball tie rod (3) and a steering actuator, wherein the housing (1) is provided with a rack (2) via a support seat (4), and both ends of the rack (2) are provided with ball tie rods (3), characterized in that: Steering actuators are respectively arranged at the two end heads of the housing (1), and the steering actuators include a main controller (5) connected to a steering wheel control central line, a drive motor (6), a worm gear and a gear shaft (7), the drive motor (6) is electrically connected to the main controller (5), the output shaft of the drive motor (6) is connected to the gear shaft (7) via the worm gear, and the gear shaft (7) is meshed with the rack (2).

2. A steering actuator for enhancing steering speed according to claim 1, characterized in that: The gear shafts (7) are respectively provided with single-axis angle signal sensors (8) for detecting the rotation angle of the gear shafts (7), and the single-axis angle signal sensors (8) are electrically connected to the main controller (5).

3. A steering actuator for enhancing steering speed according to claim 1, characterized in that: The main controller (5) is connected to the steering wheel control center via a CAN bus.

4. A steering actuator for enhancing steering speed according to claim 1, characterized in that: The contact angle between the rack (2) and the support seat (4) is 15°-33°.

5. A steering actuator for enhancing steering speed according to claim 4, characterized in that: The contact angle between the rack (2) and the support seat (4) is 30°.

6. The steering actuator for enhancing steering speed according to claim 1, characterized in that: One end of the rack (2) is provided with a connecting tooth A (9), and one end of the rack (2) is provided with a connecting tooth B (10). The connecting tooth A (9) and the connecting tooth B (10) are respectively connected to the gear shaft (7) at the two ends of the housing (1); the phase angles of the connecting tooth A (9) and the connecting tooth B (10) are the same.

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