KR950006675B1 - Four wheel steering system of electronic control hydraulic type for vehicle - Google Patents

Abstract

A four-wheel steering system comprises a steering handle (2), a steering gear system (1), a couple of hydraulic pumps (4, 4a) for front and rear wheels (3, 7), a first solenoid valve (5), an ON-OFF valve (51), a control part operating the valves and an actuator (8) controlling the rear wheel steering via the ON-OFF valve. The actuator comprises a cylinder (81), a piston (82), a couple of piston rods (71) linked to the rear wheel, a couple of springs (83), a stopper means (9) and a second solenoid valve (10) operating the stopper means. It is characterized that the stopper means may set the piston to be locked in a neutral position when the steering system is out of order. Releasing the locked piston is achieved by transferring a high pressure from the hydraulic pump for the rear wheel to the stopper means.

Description

Electronically Controlled Hydraulic Four-wheel Steering System for Vehicles

1 is a hydraulic circuit diagram of an electronically controlled hydraulic four-wheel steering device according to the present invention.

2 is an enlarged cross-sectional view of a rear wheel actuator according to the present invention.

3 is a hydraulic circuit diagram of an electronically controlled hydraulic four-wheel steering device for a conventional vehicle.

* Explanation of symbols for main parts of the drawings

8: Actuator for rear wheel 9: Locking means

10: second solenoid valve 81: piston

91: sealed container 92: locking member

93: spring

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus of an automobile, and more particularly, to an electronically controlled hydraulic steering apparatus for a vehicle provided with a locking device in a rear actuator to prevent steering of the rear wheel regardless of the driver's intention.

Steering system refers to a device that changes the driving direction of the vehicle as required by the driver by turning the steering wheel, which is an important mechanism along with the brake device for driving safety of the vehicle.

A conventional electronically controlled hydraulic four-wheel steering apparatus for automobiles will be described with reference to FIG. 3. When the steering wheel 2 is rotated to turn while driving in a straight line, the rotational force applied to the steering wheel 2 is transmitted to the steering gear unit 1, and the steering gear unit 1 operates the rod 31 to operate the steering wheel. Rotate the front wheels 3 by the steering angle of. At this time, the hydraulic pressure is transmitted from the front wheel hydraulic pump 4a to the steering gear unit 1 to operate the rod 31 beyond the force applied to the steering wheel. In other words, the front wheels rotate smoothly even if the steering wheel is rotated with a small force. At the same time as the steering wheel 2 is rotated, the steering angle and the driving speed are sensed by the steering angle sensor 21 and the vehicle speed sensor 22 and input to the controller 6. The control unit 6 turns on the on and off valves 51 that are turned off by sending a current signal in order to steer the rear wheel appropriately according to the input steering angle and the vehicle speed, and the first solenoid Activate the valve (5). That is, when the steering wheel 2 is rotated to the right, the control unit 6 turns on the on and off valves 51 which are turned off. Further, the high pressure of the rear wheel hydraulic pump 4 flows into the second chamber 81B of the cylinder 81 and the low pressure of the oil tank flows into the first chamber 81A, so that the piston 82 causes the cylinder to flow. The first solenoid valve 5 is operated to move to the right of 82 to allow the rear wheel to rotate to the right.

In the conventional automotive electronically controlled hydraulic four-wheel steering device having the above structure, when a failure occurs in the electric system, the rear wheel is not steered as required by the driver and the rear wheel is steered regardless of the driver's intention. This became impossible and there was a problem that a vehicle accident occurs.

The present invention has been made to solve the above problems, the object of the present invention is to secure the running stability by fixing the rear wheel to the neutral position in case of failure of the steering system or rear wheel should not be steered. The present invention provides an electronically controlled hydraulic four-wheel steering device for automobiles.

The present invention for achieving the above object, the steering wheel is provided with a steering sensor, the steering wheel and the shaft is connected to the medium, and the steering wheel, the oil tank and the first connecting pipe connected to the front and rear sides of the steering wheel is connected to the medium. Front wheel hydraulic pump to transfer the hydraulic pressure to the fisherman, rear wheel hydraulic pump connected to the first bypass pipe bypassed from the first connecting pipe, the first solenoid valve for controlling the hydraulic pressure of the hydraulic pump and oil tank of the rear wheel hydraulic pump And an on / off valve, a vehicle speed sensor for detecting a vehicle speed of a wheel, and a control unit which receives a signal from the steering angle sensor and instructs the operation of the first solenoid valve and an on / off valve, hydraulic pressure from the on / off valve. In the electronically controlled hydraulic four-wheel steering apparatus for automobiles provided with an actuator for steering a rear wheel, the actuator comprises a cylindrical cylinder, A piston embedded in the cylinder for dividing the cylinder into first and second chambers, a rod connecting the piston and the rear wheel, a spring embedded in the first and second chambers of the cylinder so that the piston is located at the neutral position of the cylinder, And a second solenoid valve configured to lock the piston to be positioned at the neutral position of the cylinder, and a second solenoid valve electrically connected to the control unit and transmitting hydraulic pressure to the locking means so that the locking means can operate.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the electronically controlled hydraulic four-wheel steering apparatus for automobiles according to the present invention, as shown in FIG. 1, a steering wheel 2 and a steering gear 1 are connected to a shaft 2a by a medium, and the steering gear part 1 is left. On the right outer side, the front wheel 3 is connected using the rod 31 as a medium. In addition, the steering gear unit 1 is connected to the hydraulic pump 4a for the front wheels connected to the oil tank 40 and the first connecting pipe 401 as a medium. The front wheel hydraulic pump 4a functions to transfer the pressure to the steering gear unit 1 to smoothly steer the front wheel with little force. A rear wheel hydraulic pump 4 connected to the first bypass pipe 401a bypassed from the first connecting pipe 401 is installed outside the front wheel hydraulic pump 4a, and the rear wheel hydraulic pump 4 is installed. ), A first solenoid valve 5 for controlling the hydraulic pressure sent to the rear wheel actuator 8 according to the current signal of the control unit 6 to be described below is connected to the second connecting pipe 402 by a medium. A third connecting pipe 403 connected to the oil tank 4 is connected to the first solenoid valve 5. The first solenoid valve 5 is connected to the on and off valve 51 by the fourth and fifth connection pipes 404 and 405 as a medium, and the on and off valve 51 is connected to the rear wheel actuator 8. Sixth and seventh connecting pipes 406 and 407 are connected to the medium. The actuator 8 has a built-in piston 82, a sealed cylinder 81 divided into first and second chambers 81A and 81B by the piston 82, and the piston 82 is always in a neutral state. Spring 81 is provided in the first and second chambers 81A and 81B of the cylinder to hold the cylinder, and both sides of the cylinder 81 are connected to both sides of the piston 82, and The side is formed with a rod through hole 811a through which the rod 71 connected to the rear wheel 7. The vehicle speed sensor 22 for detecting the vehicle speed and the steering angle sensor 21 for detecting the steering angle are received. A solenoid valve 5 and an on / off valve 51 are provided with a control unit 6 which sends a current signal suitable for the situation and issues a steering command, which is the same as the conventional electronically controlled hydraulic four-wheel steering device for automobiles. .

The electronically controlled hydraulic four-wheel steering apparatus for automobiles according to the present invention receives an abnormal signal from the actuator locking means 9 provided in the rear wheel actuator 8 and the control unit 6, and the locking means of the actuator 8. It is further provided with a second solenoid valve 10 for transmitting hydraulic pressure to the locking means (9) so that the (9) can operate. The locking means 9 and the second solenoid valve 10 are connected to the ninth connecting pipe 409 as a medium. The second solenoid valve 10 is connected to the second bypass 402a pipe bypassed from the second connecting pipe 402 connected to the rear wheel hydraulic pump 4 and to the oil tank 4. It is connected to the tenth connecting pipe (410a).

Referring to FIG. 2, the locking means of the actuator 8 according to the present invention will be described.

The locking means 9 is provided with a sealed container 91 in the center outside the cylinder.

The sealed container 91 has a lock member 922 integrally formed on one surface thereof and a spring 93 in contact with the other surface of the lock member 92. The airtight container 91 has a through hole 923 through which the lock rod 92 penetrates, and a ninth connecting pipe 409 extending from the second solenoid valve 10 at a lower side thereof. Communicate, combined. A lock rod guide hole 911 through which the lock rod 922 penetrates is formed in an outer surface of the cylinder 81, and a fixing groove 821 in which the lock rod 922 is fitted into an outer surface of the piston 82. Is formed. The guide hole 911 and the fixing groove 821 are formed in the longitudinal center of the cylinder 81 and the piston 82 in the longitudinal direction. This is for the piston 82 to be in the neutral position of the cylinder when the locking rod 92 is fitted into the fixing groove 821. In addition, the lock rod 922 is such that when the lock rod 922 is inserted into the fixing groove 821, the bottom surface of the sealed container 91 and the locking member 92 can have a predetermined space (9A) To form a length.

The spring 93 uses an elastic force greater than the low oil pressure transmitted from the oil tank 40 and smaller than the intrinsic pressure delivered from the second bypass pipe 42a.

The operation of the electronically controlled hydraulic four-wheel steering device for a vehicle according to the present invention having the above structure will be described.

Referring to the first state, the on / off valve 51 is turned off so that hydraulic pressure is not transmitted to the first and second chambers 81A and 81B of the cylinder, and the second solenoid valve 10 is the oil tank. The hydraulic pressure of the 40 (the tenth connection pipe 410) is transmitted, so that the low hydraulic pressure is transmitted to the sealed container 91. That is, since the elastic force of the spring 93 is greater than the low oil pressure, the locking rod 922 is inserted into the fixing groove 821. When the steering wheel 2 is rotated to turn while driving, the rotational force applied to the steering wheel 2 is transmitted to the steering gear unit 1, and the steering gear unit 1 operates the rod 31 to steer the steering angle of the steering wheel. Rotate the front wheels 3 by At this time, hydraulic pressure is transmitted from the front wheel hydraulic pump 4a to the steering gear unit 1 to operate the rod 31 with a force greater than that applied to the steering wheel. In other words, the front wheels rotate smoothly even if the steering wheel is rotated with a small force. At the same time as the steering wheel 2 is rotated, the steering angle and the driving speed are sensed by the steering angle sensor 21 and the vehicle speed sensor 22 and input to the controller 6. The control unit 6 turns on the on and off valves 51 that are turned off by sending a current signal in order to steer the rear wheel appropriately according to the input steering angle and the vehicle speed, and the first solenoid The valve 5 and the second solenoid valve 10 are operated. That is, when the steering wheel 2 is rotated to the right side, the control unit 6 turns on the on / off valve 51 which is turned off, and the second solenoid valve 10 opens the second bypass pipe 402a. Operate to transfer hydraulic pressure through. That is, the high pressure is introduced into the space 9A of the sealed container so that the locking member 92 overcomes the force of the spring 93 and the locking rod 922 can be separated from the fixing groove 821. . In addition, the high pressure of the rear wheel hydraulic pump 4 flows into the second chamber 81B of the cylinder 81 and the low oil pressure of the oil tank flows into the first chamber 81A, so that the piston 82 causes the cylinder ( The first solenoid valve 5 is operated to move to the right of 82) so that the rear wheel can rotate to the right.

As described above, when an abnormality occurs in the electric system during the turning or linear driving, the control unit 6 allows the second solenoid valve 10 to be connected to the tenth connecting pipe 410 so that the oil tank 40 is low. Hydraulic pressure is to flow into the sealed container (91). Then, since the spring 93 force is greater than the low oil pressure, the locking rod 922 is inserted into the fixing groove 821 by the spring 93 force, and the piston 82 is fixed at the neutral position. The rear wheels are not steered. Even when driving on a dirt road, the rear wheels are not steered as described above.

As described above, the present invention can secure the stability by fixing the rear wheel in a neutral position when the rear wheel can not be steered at the driver's will because of a failure in the system of the steering system, and the rear wheel by external impact The steering can be prevented and the driver can drive safely.

Claims (3)

A steering handle 2 having a steering sensor 21 installed thereon, the steering handle 2 and a shaft 2a connected to a medium, and a steering gear unit 1 and an oil tank 40 to which front wheels 3 are connected at left and right sides thereof. Front wheel hydraulic pump 4a for connecting hydraulic pressure to the steering gear unit 1 by connecting the first connecting pipe 401 to the medium, and the first bypass pipe 401a bypassed from the first connecting pipe 401. And a first solenoid valve 5 for controlling the hydraulic pressure of the rear wheel hydraulic pump 4 and the hydraulic pressure of the oil tank 40 and the on / off valve 51 and the vehicle speed of the wheel connected to the rear wheel hydraulic pump 4. The control unit 6 that receives a signal from the vehicle speed sensor 22 and the steering angle sensor 21 to sense the operation of the first solenoid valve 5 and the on, off valve 51 to command the operation, the on In the electronically controlled hydraulic four-wheel steering device for an automobile provided with an actuator for receiving hydraulic pressure from the off valve 51 to steer the rear wheel, the actuator (8) , A cylinder (81) having a cylindrical shape, a piston (82) for dividing the cylinder (81) into first and second chambers (81A, 81B) embedded in the cylinder (81), and connecting the piston (82) and the rear wheels; The rod 83 and the piston 82 are built in the first and second chambers 81A and 81B of the cylinder 81 so that the piston 82 is located at the neutral position of the cylinder 81, the piston 82 ) Is a lock means (9) for fixing to be positioned in the neutral position of the cylinder 81, the control unit (6) is electrically connected to the hydraulic means to the lock means (9) to operate the lock means An electronically controlled hydraulic four-wheel steering device for a vehicle, comprising a second solenoid valve 10. The method of claim 1, wherein the second solenoid valve 10 to maintain the lock by transmitting the low oil pressure of the oil tank 40 to the locking means by the command of the control unit in the event of a failure of the steering device. , The electronically controlled four-wheel steering device for a vehicle, characterized in that provided to release the lock by transmitting the high pressure of the hydraulic pressure for the rear wheel (4) to the locking means. The method of claim 1, wherein the locking means is provided on the outer surface of the cylinder 81, the through hole 923 is formed on the lower surface, the lower side of the connecting pipe extending from the second solenoid valve (10) 409) a sealing member 91 which is in communication with the hydraulic pressure supplied to the hydraulic container, a locking rod 922 which is built in the sealing container 91 and reciprocates between the through holes 923 and is integrally formed on one surface thereof. 92, a spring 93 which is in contact with the other surface of the locking member 92 and built into the sealed container 91, a guide hole 911 of the locking rod 922 formed on the outer surface of the cylinder 81, Electronically controlled four-wheel steering device for a vehicle, characterized in that provided on any one surface of the piston (82) having a fixing groove (821) for supporting the locking of the locking rod (922).