Independent steering mechanism of controllable hydraulic locking type for left and right wheels

Abstract

An independent steering mechanism of controllable hydraulic locking type for left and right wheels is provided. The independent steering mechanism includes a power steering mechanism, a steering drive mechanism, a hydraulic locking mechanism and an electronic control unit. Power of the left and right steering motors flows through the worm, the worm gear, the gear to drive left and right racks to translate. Outer ends of the left and right racks are connected to left and right tie rods via spherical hinges respectively. Inner ends of the left and right racks are connected to a piston rod and a cylinder barrel via spherical hinges respectively. A left chamber and a right chamber in the hydraulic cylinder are connected to an oil reservoir via an electro-hydraulic valve. The left and right steering motor controllers for the left and right steering motor and the electro-hydraulic valve controller are communicated via CAN bus.

Claims

1. An independent steering mechanism of controllable hydraulic locking type for left and right wheels, comprising a power steering mechanism, a steering drive mechanism, a hydraulic locking mechanism and an electronic control unit, wherein left and right steering motors are fixed on a shell of the power steering mechanism, an output shaft of the left and right steering motors is connected to a worm via a coupler respectively, a worm gear and a gear are coaxial and connected via an electromagnetic clutch, and are fixed on the shell of the power steering mechanism via a bearing; a power of the left and right steering motors flows through the worm, the worm gear, the gear to drive left and right racks to translate, outer ends of the left and right racks are connected to left and right tie rods via a spherical hinge and a spherical hinge respectively; inner ends of the left and right racks are connected to a piston rod and a cylinder barrel of a hydraulic cylinder via a spherical hinge respectively; the shell of the power steering mechanism and a connection baseboard of the steering mechanism are mounted on a subframe; oil outlets of a left chamber and a right chamber of the hydraulic cylinder are connected to an electro-hydraulic valve, and the other end of the electro-hydraulic valve is connected to an oil reservoir fixed to a vehicle body; the electro-hydraulic valve is controlled by an electro-hydraulic valve controller to be closed or opened, so as to realize an independent motion of the left and right steering wheels and an integral motion of the left and right steering wheels; left and right steering motor controllers for the left and right steering motor and the electro-hydraulic valve controller are communicated via CAN bus.

2. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 1, wherein a rubber bushing is disposed between the shell and the baseboard so as to reduce an external impact on the steering system.

3. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 2, wherein the worm gear and the gear are coaxial, and can rotate together and rotate separately by close or open of the electromagnetic clutch.

4. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 2, wherein there are lubricants on the spherical hinges and the left and right racks; a dust cover is provided at the spherical hinges and the left and right racks, and a joint of the shell of the power steering mechanism and the left and right racks.

5. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 2, wherein an angle and torque of the steering wheel and a vehicle speed signal are sent to the CAN bus by sensors; the left and right steering motor controllers and the electro-hydraulic valve controller receive corresponding messages from the CAN bus and send out corresponding instructions, so as to control the motion of the left and right steering motors, the actions of the electro-hydraulic valve and the electromagnetic clutch.

6. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 1, wherein there are lubricants on the spherical hinges and the left and right racks; a dust cover is provided at the spherical hinges and the left and right racks, and a joint of the shell of the power steering mechanism and the left and right racks.

7. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 1, wherein the worm and the worm gear are adopted as a decelerating mechanism.

8. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 1, wherein an angle and torque of the steering wheel and a vehicle speed signal are sent to the CAN bus by sensors; the left and right steering motor controllers and the electro-hydraulic valve controller receive corresponding messages from the CAN bus and send out corresponding instructions, so as to control the motion of the left and right steering motors, the actions of the electro-hydraulic valve and the electromagnetic clutch.

9. The independent steering mechanism of controllable hydraulic locking type for left and right wheels according to claim 1, wherein the worm gear and the gear are coaxial, and can rotate together and rotate separately by close or open of the electromagnetic clutch.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic diagram illustrating a device provided by the present disclosure;

(2) FIG. 2 is a schematic diagram illustrating a transmission shaft at a worm gear of the device provided by the present disclosure;

(3) FIG. 3 is a schematic diagram illustrating a hydraulic system when the device provided by the present disclosure is locked.

LIST OF REFERENCE NUMERALS

(4) 1: left steering motor; 2: dust cover; 3: electro-hydraulic valve; 4: hydraulic cylinder; 4a: piston rod; 4b: cylinder barrel; 5: oil reservoir; 6: right steering motor; 7: worm; 8: worm gear; 9: shell of power steering mechanism; 10: right rack; 11: right steering tie rod; 12: gear; 13: right steering motor controller; 14: electro-hydraulic valve controller; 15: left steering motor controller; 16: steering mechanism connection baseboard; 17: left steering tie rod; 18a: spherical hinge I; 18b: spherical hinge II; 18c: spherical hinge III; 18d: spherical hinge IV; 19: left rack; 20: electromagnetic clutch.

DETAILED DESCRIPTION

(5) Specific contents and embodiments of the present disclosure are further described below in combination with accompanying drawings.

(6) Referring to FIG. 1 and FIG. 2, which illustrate an implementing solution of a kind of structure of the mechanism provided by the present disclosure, including a left steering motor 1, a dust cover 2, an electro-hydraulic valve 3, a hydraulic cylinder 4, a piston rod 4a, a cylinder barrel 4b, an oil reservoir 5, a right steering motor 6, a worm 7, a worm gear 8, shell 9 of a power steering mechanism, a right rack 10, a right steering tie rod 11, a gear 12, a right steering motor controller 13, an electro-hydraulic valve controller 14, a left steering motor controller 15, a steering mechanism connection baseboard 16, a left steering tie rod 17, a spherical hinge 18, a left rack 19, an electromagnetic clutch 20.

(7) Referring to FIG. 1 and FIG. 2, the left steering motor 1 and right steering motor 6 are fixed to the shell 9 of the power steering mechanism. The worm gear 8 and gear 12 are connected via an electromagnetic clutch 20, and are fixed on the shell 9 of the power steering mechanism via a bearing. The power of the motors flows through the worm 7, the worm gear 8, the gear 12 to drive the left rack 19 and right rack 10 to translate. A left end of the left rack 19 is coupled to the left tie rod 17 via the spherical hinge 18a, and a right end of the left rack 19 is coupled to the piston rod 4a via the spherical hinge 18b. A left end of the right rack 10 is coupled to the cylinder barrel 4b of the hydraulic cylinder 4 via the spherical hinge 18c, and a right end of the right rack 10 is coupled to the right steering tie rod 11 via the spherical hinge 18d. The spherical hinges increase freedom degrees of the motion of the system, prevents kinematic interference caused by the jitter and steering of the wheels. A rubber bushing is disposed between the shell 9 of the power steering mechanism and the connection baseboard 16 of the steering mechanism to reduce an impact on the steering system by externality. The independent motion and integral motion of the left and right steering wheels can be realized by controlling the turning on and off of the electro-hydraulic valve 3. The whole steering system are fixed on the subframe via the connection baseboard 16 of the steering mechanism.

(8) As shown in FIG. 1, when the electro-hydraulic valve 3 is powered off, the left and right chambers of cylinder 4 are connected to the oil reservoir 5. The piston rod 4a can freely move relative to the cylinder barrel 4b. The left rack 19 and right rack 10 can move relative to each other. Therefore, an independent steering of the left wheel and right wheel can be realized. When the electro-hydraulic valve 3 is powered on, under the electromagnetic force, the electro-hydraulic valve 3 overcomes the spring force and reaches a working condition as shown in FIG. 3. At this time, no fluid flows between the left and right chambers of the hydraulic cylinder 4 and the oil reservoir 5. The piston rod 4a is stationary relative to the cylinder barrel 4b, thus there is no relative displacement between the left rack 19 and right rack 10. Therefore, the left and right steering wheels are switched to the integral motion from the independent motion. When it is required to switch the left and right steering wheels to the independent motion from the integral motion, the electro-hydraulic valve 3 is powered off. As a result, under the action of a return spring, the electro-hydraulic valve 3 restores to the working condition as shown in FIG. 1.

(9) As shown in FIG. 1, in normal working conditions, the electro-hydraulic valve 3 is powered off. When a vehicle is driving in a straight line, due to the self-locking of the worm and worm gear mechanism, the vehicle can keep driving in a straight line even if it is under the external interference.

(10) As shown in FIG. 1, when the vehicle makes a turn, the electro-hydraulic valve 3 is powered off. The left and right steering motor controllers 15, 13 receive signals such as the vehicle speed, angle and torque of the steering wheel from the CAN bus, and compute the angles rotated by the left and right steering motors 1, 6 according to a preset control algorithm. In addition, the left and right steering motor controllers 15, 13 control the positions of the left and right steering motors 1, 6, so as to make them turn a corresponding angle. Then, the left and right steering motors 1, 6 drive the worm gear 8 to rotate via the worm 7. At this moment, the electromagnetic clutch 20 is in a closed state. The worm gear 8 drives the gear 12 to rotate, and then the gear drives the racks to move in a straight line. The left and right rack 19, 10 have different displacement through a relative motion between the piston rod 4a and the cylinder barrel 4b. The left and right racks 19, 10 drive the left and right steering tie rods 17, 11 to move. The left and right steering tie rods are connected to knuckles. The knuckles drive the steering wheels to rotate around a master pin so as to realize the steering motion.

(11) When the vehicle makes a turn, the left and right steering motor controllers 15, 13 receive information such as the angle of the steering wheel and the vehicle velocity from the CAN bus. Based on the geometry of the current steering trapezium, in view of side slip characteristics of the tire, turning angle of the left steering wheel and right steering wheel can adjusted separately, so as to guarantee centers of the tracks of the steering wheels coincide. Therefore, the wearing of the tires will be reduced.

(12) When the vehicle is in an emergency (e.g., emergency obstacle avoidance, yaw velocity rapidly increasing due to over-steering or losing control of the vehicle), the left and right steering motor controllers 15, 13 determine the occurrence of abnormal conditions based on information from the CAN bus, such as yaw velocity, vehicle speed. If abnormal conditions happen, the controllers adjust turning angles of the steering motors to modify the driving track of the vehicle. The process can combine with ESP system to improve active security of vehicle.

(13) When the vehicle requires to be in special steering conditions, such as spot turn, front axle-rear axle steering, the controllers controls the turn angles of the steering motors based on a preset control strategy.

(14) As shown in FIGS. 2, 3, when the steering motors on one side break down, due to the self-locking characteristic of the worm gear transmission, the rack cannot drive the worm 7 to rotate via the gear 12 and worm gear 8. At this moment, the electromagnetic clutch 20 on the side that is break down releases, meanwhile the electro-hydraulic valve 3 is powered on. Therefore, the left rack 19 and the right rack 10 are locked together. As a result, the undamaged steering motor drives the left and right steering wheels to rotate.

(15) In conclusion, the mechanism provided by the present disclosure can realize independent motion of the left and right steering wheels, and can be locked under specific working conditions. The whole steering system has great controllability and operational reliability.