JPH0725323B2 - Front and rear wheel steering system used in automobiles - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front and rear wheel steering system used in an automobile in which rear wheels are steered in connection with steering of front wheels.

BACKGROUND ART In recent years, in automobiles, front and rear wheels are steered to steer front wheels and rear wheels, and there is a tendency to improve steerability and traveling stability.

The front and rear wheels are normally steered by the front power steering and the rear power steering, and the control valve of the rear power steering also has its front power by the link mechanism including a long relay rod. A steering input coupled to the steering and via its linkage switching, steering input is provided to the rear power steering, so that the rear power steering is associated with steering of the front power steering I will be made to steer.

Therefore, in the link mechanism using the long relay rod, there are often cases where the arrangement is space-constrained, which makes the placement of the link mechanism very difficult.

Further, in steering the front and rear wheels without using such a link mechanism, the entire device tends to be complicated and expensive.

Objects and problems of the present invention are assured that reliability is ensured, steering input can be transmitted from front steering to rear power steering by a simple means, and rear wheels are related to steering of front wheels. In order to provide a front and rear wheel steering system that is used in a vehicle that is easily arranged without being restricted in space, a means for transmitting steering input by means of a steering wheel is provided.

Another object and problem of the present invention is to ensure fail-safe operation of a rear power steering when a failure occurs in a means for transmitting a steering input, thereby ensuring reliability and safety in driving a vehicle. To provide front and rear wheel steering systems for use in automobiles.

SUMMARY OF THE INVENTION FOR OBJECTS AND PROBLEMS In connection with the above objects and problems, a front and rear wheel steering system used in an automobile according to the present invention includes front steering for steering front wheels and rear wheels. In relation to the rear power steering to steer, its front steering and rear power steering, it extends in the left and right direction of the chassis between its front wheels and its rear wheels and is rotatably supported on its chassis side. Then, the control beam that is swung in the front and rear direction of the chassis by the front steering, the pair of phase switching racks that are reciprocally supported by the control beam, and the phase switching rack for the control beam. A reciprocating electric actuator and the left and right direction of the chassis behind the control beam A pair of fixed rails, which are arranged at a predetermined interval and extend in the front-rear direction of the chassis and are fixed to the chassis side, a pair of fixed rail sliders that are fitted to the corresponding fixed rails, and their controls. · A pair of movable rails that are extended in the left and right direction of the chassis behind the beam and are fixed to the corresponding fixed rails and sliders, and can be fitted to the corresponding movable rails and rotated to the corresponding phase switching rack A pair of movable rail sliders, one end of which is connected to its corresponding fixed rail slider and the other end of which is connected to the control valve of the rear power steering, and a pair of control signals and vehicle speed sensor signals. The electric actuator to reciprocate the pair of phase switching racks according to the And a control unit for controlling the electric current flowing through the electric actuator in response to a signal from the vehicle speed sensor to drive the electric actuator, which is associated with steering of the front steering wheel. The electric actuator moves the pair of phase switching racks in the control beam to control the swing of the control beam so that the phase and the steering angle of the rear wheel are determined. The dynamics actuate the control valves on the rear power steering and drive the rear power steering to steer the front and rear wheels.

Further, the front and rear wheel steering system used in the automobile of the present invention has a front steering for steering the front wheels and a rear steering for steering the rear wheels having a control valve for centering the spool by either spring or fluid pressure. The power steering and its front and rear power steering in relation to its front and rear wheels, extending laterally of the chassis and rotatably supported on its side, and front·
A control beam that is swung in the front-rear direction of the chassis by steering, a pair of phase-switching racks that are reciprocally supported by the control beam, and electricity that causes the control beam to reciprocate. The actuator and a pair of fixed rails which are arranged behind the control beam at a predetermined distance in the left-right direction of the chassis and extend in the front-rear direction of the chassis and are fixed to the chassis side, and the corresponding rails. A pair of fixed rail sliders fitted to the fixed rails, a pair of movable rails extending in the left-right direction of the chassis behind the control beam and fixed to the corresponding fixed rail sliders, and their corresponding It is fitted to a movable rail and turned to its corresponding phase switching rack. Possible and a pair of movable rail slider coupled to the safety cable to be broken at least a predetermined tensile load using at least a portion, and, at one end to the fixed rail sliders its corresponding, the rear and the other end
It includes a pair of control cables respectively connected to the control valves of the power steering, and a control unit for causing the electric actuator to reciprocate the pair of phase switching racks in response to a signal from a vehicle speed sensor, and the control thereof. The unit controls the current flowing through the electric actuator in response to the signal from the vehicle speed sensor to drive the electric actuator, and determines the phase and the steering angle of the rear wheels in relation to the steering of the front steering. As described above, the electric actuator moves the pair of phase switching racks in the control beam to control the swing of the control beam, and the swing of the control beam controls the rear power steering control. Operate the valve Drive its rear power steering to steer its front and rear wheels, and if an unreasonable force is applied to the means for transmitting the phase and steering angle to its control valve, the safety cable will The control cable is broken, and at the control valve, the spool is moved to the neutral position and so-called centering is performed to operate the rear power steering in a fail-safe manner.

Description of Specific Examples Specific examples of the front and rear wheel steering systems used in the vehicle according to the present invention will be described with reference to the drawings.

1 to 7 show a tenth embodiment of the front and rear wheel steering system used in the automobile of the present invention used for the truck 70.

The front and rear wheel steering system 10 centers a spool (not shown) with a front steering 11 that steers the front wheels 75 and 76 and a spring (not shown). Rear power steering 12 that has rear control valve 39 and steers rear wheels 83,84,85,86, and control beam
13, a pair of phase switching racks 14 and 15, an electric actuator 16, a pair of fixed rails 17 and 18, a pair of fixed rail sliders 19 and 20, a pair of movable rails 21 and 22, and a pair of movable rails. Rail sliders 23, 24 and a pair of control cables 25, which use safety cables 27, 28 in part
26 and a control unit 29 are included,
Its front steering 11 enables its front wheels 75,76 to be steered and, at the same time, its rear power steering.
12 makes the rear wheels 83,84,85,86 steerable in relation to the steering angle and vehicle speed of its front wheels 75,76 and, more specifically, when its truck 70 is driven at low speeds. , The rear-axis cutting angle is opposite to the front-axis cutting angle, and
When the truck 70 travels at high speed, the rear wheel turning angle is in phase with the front wheel turning angle and the rear wheels 83,8
It is possible to steer 4,85,86.

The front steering 11 is a front booster
30, front control valve 31, oil body pump (not shown), flow control valve (not shown), steering wheel 32, steering shaft 33, pitman arm 35, drag link 36,
And a knuckle arm 37, and configured for power steering.

Also, in this front power steering 11, its front booster 30, front control valve 31, hydraulic pump, flow control valve,
And an oil reservoir (not shown) are connected to the hydraulic circuit by front supply hydraulic lines (not shown) and front return hydraulic lines (not shown), and their flow control valves are -It is connected to the front return hydraulic line by a booster bypass (not shown).

The front booster 30 incorporates the front control valve 31 in the cylinder body,
It is manufactured in a normal integral type including a manual steering mechanism. A piston is fitted in the cylinder bore of the cylinder body so that it can slide back and forth, and a pair of cylinders is placed in the cylinder bore. A chamber is defined and a sector shaft 34 is meshed with the piston to transfer the force and movement of the piston to the Pitman arm 35.

As such, its front booster 30, which is built in a normal integral form, is also the chassis of its truck 70.
A front axle 72 arranged in front of 71 is swingably connected to both ends of the front axle 72 via a knuckle and a king pin, and its front wheel 7
A pair of front wheel shafts 73 and 74 that rotatably support 5,76 respectively.
To the pitman arm 35, the drag link 36, and the knuckle arm 37. Of course, the front wheel shafts 73 and 74 are connected to each other by a tie rod 77 and a pair of tie rod arms 78 and 79.

The front control valve 31 is manufactured in the same manner as the control valve of a normal integral type power steering, and the steering
It is geared to the shaft 33 and is operated by its steering wheel 32 via its steering shaft 33. Of course, this front control valve 31
As it is operated with the steering wheel 32,
The pressure oil discharged from the hydraulic pump and the flow rate of which is adjusted by the flow control valve are selectively supplied to the pair of cylinder chambers of the front booster 11, and at the same time, the pair of cylinder chambers of the front booster 11 are simultaneously supplied. Pressure oil is selectively returned to its oil reservoir.

The hydraulic pump is manufactured in the same manner as the hydraulic pump used for normal power steering and is arranged in the front supply side hydraulic pipe.

In addition, this hydraulic pump is driven by a diesel engine (not shown) mounted on the truck, sucks up oil from its oil reservoir, pressurizes it, and pressurizes oil proportional to the rotational speed of the diesel engine. The discharge amount of is obtained.

The flow control valve is a normal power
Made in the same way as the flow control valve used for steering, it is placed in its front supply side hydraulic line between its hydraulic pump and its front control valve 31, and also in the front booster bypass. It is connected to the front return hydraulic line.
Of course, this flow control valve regulates the flow rate of the pressure oil supplied from the hydraulic pump to supply a predetermined flow rate of pressure oil to the front booster 30 and the rear booster 38, and Return excess flow of pressure oil to its oil reservoir via its front booster bypass.

The rear power steering 12 is the front
The power steering 11 hydraulic pump, flow control valve, and oil reservoir are shared, and their rear booster 38 and rear control valve 39 are provided on them to the rear supply hydraulic line (not shown) and rear return. It is configured by connecting side hydraulic piping (not shown), the cylinder body 40 of the rear booster 38 is pivotally connected to the tie rod arm 89, and the piston rod 41 of the rear booster 38 is connected. Bracket 42 on rear axle 80
Via a tie rod 87, and a pair of rear wheel shafts 81, 82 rotatably supporting rear wheels 83, 84, 85, 86 which are pivotally connected to both ends of the axle 80. It is also steerable via a pair of tie rod arms 88 and 89.

Further, in the rear power steering 12, the rear control valve 39 is incorporated in the cylinder body 40 of the rear booster 38.

As described above, the rear control valve 39 has the spool whose center is centered by the spring, and when the steering input is not applied, the rear booster 38 has: A piston (not shown) is held in a neutral position in the cylinder bore of the cylinder body 40. That is, the rear control valve 39 operates the rear power steering 12 in a fail-safe manner to make the running of the truck 70 safe. Of course, the rear control valve 39 functions similarly even if the spool is manufactured in a structure in which the spool is hydraulically centered in the state where the steering input is not applied.

Its control beam 3 is its front power steering 11 and rear power steering 12
In relation to the front wheels 75,76 and rear wheels 83,84,85,86, the chassis 71 is extended in the left-right direction and rotatably supported on the chassis 71 side, and its front power The steering wheel 11 is swung in the front-rear direction of the chassis 71, and in this case, it is manufactured in an elongated box shape so as to support the phase switching racks 14 and 15 so as to be capable of reciprocating.

More specifically, the control beam 13
Turn the opening 44 rearward and attach both ends to the chassis 71
Is rotatably supported by a pin 47 of a bracket (not shown) fixed to the chassis 71 in a set state of facing both sides. Of course, the control beam 13 is connected to the drag link 36 of the front power steering 11 through a relay rod 48 that is pivotally connected, and is transmitted through the relay rod 48. The steering angle of the front wheel, that is, the steering of the front power steering 11, causes the front power steering 11 to swing around the pin 47 in the horizontal plane.

In particular, the relay rod 48 is connected to the control beam 13 by a ball joint, but when the displacement amount of the ball joint connection portion is smaller than the displacement amount of the drag link 36. A pair of springs (not shown) that absorb rod displacement, that is, rod displacement in the so-called push-pull direction above a predetermined load, are arranged in the ball-joint connecting portion in a facing state.

Further, as can be understood from FIGS. 2 and 3, the control beam 13 is provided with a pair of guide grooves 45, 46 extending in the beam length direction, and the guide grooves 45, 46 are provided in the phase change rack. It is manufactured to have a structure in which the phase change racks 14 and 15 are supported by reciprocatingly fitting them in correspondence with each other.

The pair of phase change racks 14 and 15 are provided with guide grooves 4 of the control beam 13 as can be seen from FIG.
The tooth flanks 49, 50 face each other with a predetermined spacing, which are fitted in correspondence with each other.

As such, the phase change racks 14, 15 have their guide grooves 4
It is reciprocally movable to 5,46 and supported by its control beam 13.

The phase switching racks 14 and 15 also include arms 51 and 52 that connect the control beam 13 to the control cables 25 and 26. Of course, the arm 51,
52 is projected to a predetermined position of the phase switching racks 14 and 15, and the phase switching racks 14 and 15 are fitted into the guide grooves 45 and 46 of the control beam 13 so that the control beam It extends rearward from the opening 44 of 13.

The arms 51 and 52 are attached to the pair of fixed rail sliders 19 and 20 fitted to the pair of fixed rails 17 and 18, and the fixed rail sliders 19 and 20, respectively, as described later in detail. The pair of fixed movable rails 21 and 22 and the pair of movable rail sliders 23 and 24 fitted to the movable rails 21 and 22 are interposed to the corresponding control cables 25 and 26. Be connected.

The electric actuator 16 is a stepping motor, and its phase-shifting rack 1 is driven through a reduction gear mechanism.
4 and 15 and reciprocates the phase change racks 14 and 15 into the guide grooves 45 and 46 of the control beam 13.

In this electric actuator 16, a motor shaft 54, which supports a rotor (not shown), has a predetermined center of rotation of its control beam 13, a so-called rotation axis RA, as shown in FIGS. 1 and 3. Crossed at right angles at intervals, the motor housing 53 is
It is screwed to 13 and a stator (not shown) is placed in its motor housing 53 around its rotor and its windings (not shown) are attached to its control unit 29. It is electrically connected to the output circuit.

The electric actuator 16 thus assembled to the control beam 13 also fixes a motor gear 55 to the rotor motor shaft 54 and, via its reduction gear mechanism, to the phase-shifting rack 14. , 15 can transmit power.

The reduction gear mechanism connects the reduction gear 56 meshed with the motor gear 55, the pinion 57 meshed with the phase switching racks 14 and 15, and the reduction gear 56 and the pinion 57 to each other. State those reduction gears
56 and a shaft 58 supporting a pinion 57.

In particular, in this reduction gear mechanism, the pinion 57 is engaged with the phase switching racks 14, 15 in a direction orthogonal to the rotation axis RA of the control beam 13 with the axis of the shaft 58 at a predetermined interval. Aligned.

The pair of fixed rails 17 and 18 are arranged at a predetermined interval in the left-right direction of the chassis 71 behind the control beam 13, and are extended in the front-rear direction of the chassis 71 to be mounted on the bracket 59 of the chassis 71. Fixed to.

In particular, the fixed rails 17, 18 are swung about their pin 47 in the swing range of their control beam 13,
Specifically, the length is determined in relation to the vertical movement range of the chassis 71.

The pair of fixed rail sliders 19 and 20 are fitted to correspond to the fixed rails 17 and 18, and the fixed rail 1
It is swingably supported by 7,18.

The fixed rail sliders 19 and 20 are pivotally connected to one ends of the control cables 25 and 26 so that the movement of the control beam 13 can be transmitted to the control cable 2526.

The pair of movable rails 21 and 22 extend rearward of the control beam 13 in a direction orthogonal to the fixed rails 17 and 18, and extend in the left-right direction of the chassis 71 to form the fixed rail sliders 19 and 20. Fixed in correspondence with.

Further, the movable rails 21 and 22 have a swing range of the control beam 13 which is swung around the pin 47,
Specifically, the length is determined in relation to the lateral movement range of the chassis 71.

The pair of movable rails / slider 23, 24 and the movable rails 21, 22 are fitted in correspondence with each other.
22 is slidably supported.

The movable rail sliders 23 and 24 are pivotally connected to the ends of the arms 51 and 52 of the phase switching racks 14 and 15, and the movable rails and the movable rails are moved by the movement of the phase switching racks 14 and 15. Slided on 21,22.

The pair of control cables 25, 26 are manufactured in a normal push-pull cable type, and include outer cables 60, 61, inner cables 62, 63, and inner cables 62, 63 of the outer cables 60, 61. It consists of safety cables 27 and 28 used in part.

The outer cables 60, 61 are
The middle part is fastened to the chassis 71 with a clip (not shown).

On the other hand, the inner cables 62, 63 use the safety cables 27, 28 at one end, and the safety cables 27, 28 are pivotally coupled to the fixed rail sliders 19, 20 and the The other end of the inner cables 62, 63 is the spool shaft of its rear control valve 39.
43, and the movement of its control beam 13, i.e. the rear wheel steering angle, to its rear control valve 39.
Can be transmitted to.

The safety cables 27, 28 are, of course, the inner cables 62, 63 when the inner cables 62, 63 are broken.
Designed to have a predetermined tensile load that is predetermined to a value smaller than the tensile load of the control beam 13
Of the rear wheel steering angle, that is, the rear wheel steering angle, is broken when an excessive force is applied to the rear control valve 39, and then the transmission of the wheel steering angle is interrupted.

As such, the safety cables 27, 28 are designed so that if the safety cables 27, 28 are broken, the rear
In the control valve 39, the spool is moved to a neutral position by a spring (not shown), so that its rear power steering 12 is moved fail-safe.

In that way, the safety cables 27, 28 have a mechanism for transmitting the movement of the control beam 13 at the rear wheel steering angle to the rear control valve 39, that is, a so-called rudder angle transmitting means. When it occurs, steering of the rear wheels 83, 84, 85, 86 by the rear power steering 12 is blocked, and the safety of the truck 70 is ensured in traveling.

The control unit 29 includes an input circuit, a memory circuit, an arithmetic circuit, a control circuit, an output circuit, a power circuit, and the like, and the memory circuit includes a vehicle speed and a front wheel steering angle, a so-called front power steering 11 thereof. Of the rear wheel steering angle with respect to the steering direction, the steering speed, and the steering amount of the vehicle. In other words, a program for determining the rear axle steering angle with respect to the front axle steering angle in relation to the vehicle speed is stored in advance and stored. The electric actuator 16 is constructed in such a way that the program is operated according to the signal input from the sensor 66 and the current flowing in the electric actuator 16 is controlled, and the electric actuator 16 is operated according to the signal from the vehicle speed sensor 66.
Then, the pair of phase switching racks 14 and 15 are reciprocated.

That is, the control unit 29 calculates the program according to the signal from the vehicle speed sensor 66, controls the current flowing through the stator winding of the stepping motor 16, and reduces the speed reduction gear mechanism 55, 56, 57. Via its stepping motor 16 to move its phase-shifting racks 14, 15 into the guide grooves 45, 46 of its control beam 13 and thus, in relation to the vehicle speed, the rear wheel steering angle relative to the front wheel steering angle. The rear wheel steering angle, specifically, by allowing the control beam 13 to swing around the pin 47 at a rotation angle corresponding to the rear wheel steering angle. Is to make it possible to steer the rear wheels 83, 84, 85, 86 in the opposite phase with respect to the front shaft turning angle or with the rear shaft cutting angle in the same phase with respect to the front shaft cutting angle. .

The vehicle speed sensor 66 detects the traveling speed of the truck 70, and is arranged on the output shaft of a transmission (not shown) mounted on the truck 70.

Next, when the truck 70 travels, steering by the front and rear wheel steering system 10 manufactured as described above will be described.
If the truck 70 runs at a low speed on a straight road, the hydraulic pump is driven by the diesel engine, so the pressure oil discharged from the hydraulic pump flows through the flow control valve. A regulated, predetermined flow of pressure oil flows through its front and rear supply side hydraulic lines and is sent to its front and rear control valves 31, 39.

Since the spool is placed in the neutral position, the pressure oil is returned to the oil reservoir via the front and rear return-side hydraulic pipes, and at the front and rear boosters 30, 38, respectively. Pistons are held in the neutral position.

On the other hand, the control unit 29 inputs a signal from the vehicle speed sensor 66, controls the current flowing through the electric actuator 16, drives the electric actuator 16, and, as shown in FIG. , I.e., via its reduction gear 56 and pinion 57, slide its phase switching racks 14, 15 into the guide grooves 45, 46 of its control beam 13 and, accordingly, on its movable rails 21, 22. The movable rail sliders 23, 24 are slid, and at the same time, the control beam 13 moves the front wheel.
Its front power steering that steers 75,76 1
As it is swung around its pin 47 by 1, its control beam 13 is swung around its pin 47 and on its fixed rail 17,18 its fixed rail slider 19,20. Is slid to generate a rear-wheel steering angle related to the front-wheel steering angle with the rear-axis steering angle with respect to the front-axis steering angle in the opposite phase.

From such a running condition, if the truck 70 attempts to turn left along the road at low speed, as shown in FIG. 6, the steering wheel 32 will
It is rotated to the left.

As such, if the steering wheel 32 is rotated to the left, in the front power steering 11, the front control valve 31 is operated via its steering shaft 33, The pressure oil discharged from the hydraulic pump and flow-controlled by the flow control valve is supplied to one cylinder chamber of the front booster 30, and the pressure oil of the other cylinder chamber of the front booster 30 is also supplied. Is returned to its oil reservoir.

As a result, in the front booster 30, the piston is slid from one cylinder chamber to the other cylinder chamber, and the sector gear meshed with the rack of the piston is rotated, so that the shaft of the sector gear is rotated. The pitman arm 35 fixed to 34 is swung backward in FIG.

As such, when the pitman arm 35 is swung backward, the drag link 36 is pushed in the direction by the pitman arm 35, and accordingly, the drag link 36 is rotatably supported by the front wheel shafts 73 and 74. The front wheel where it is being done 7
5,76 is steered leftward through its knuckle arm 37, tie rod 77, and tie rod arms 78,79.

As such, its front power steering 11
But when he steers its front wheels 75,76, the relay rod 4
8 is pushed backwards by its drag link 36, with its control beam 13 being swung backwards around its pin 47, in other words from the state shown in FIG. It is swung counterclockwise about its pin 47 and, at the same time, by its control unit 29, electric actuator 16, reduction gear 56, and pinion 57, its phase-shifting racks 14, 15, movable rail sliders 19, 20. However, since the fixed rails 17 and 18 are in the state shown in FIG. 4, the control beam 13, phase switching racks 14 and 15, fixed rails 17 and 18, fixed rail
Sliders 19, 20, movable rails 21, 22, and movable rails
The sliders 23, 24 cooperate with each other to generate the rear wheel steering angle, which is the opposite of the front wheel steering angle and the rear wheel steering angle, and is related to the front wheel steering angle.

As such, when the control beam 13 is swung in a counterclockwise direction about its pin 47 in FIG. 1, its control cable 25, as shown in FIG. The inner cable 62 is pulled against the outer cable 60 and, at the same time, in the control cable 26, the inner cable 63.
Is pushed against the outer cable 61.

As such, as a result of the control cables 25, 26 being pushed and pulled, the rear control valve 39 has a spool shaft 43 connected to the inner cables 62, 63 that causes the spool to move to the valve body. Of the other side of the rear booster 38 through the rear supply side hydraulic pipe, and the pressure oil that is slid into the valve bore of the rear pipe, is discharged from the hydraulic pump, and is flow-regulated by the flow control valve. The pressure oil supplied to the cylinder chamber (not shown) and in one cylinder chamber (not shown) of the rear booster 38 is returned to the oil reservoir via the rear return side hydraulic pipe.

As a result, in the rear booster 38, since the piston slides from the other cylinder chamber to the one cylinder chamber,
Since the piston rod 41 is pushed out of the cylinder body 40, the rear wheels 83, 84, 85, 86, which are rotatably supported by the rear wheel shafts 81, 82, are as shown in FIG. , And is steered to the right through the tie rod 87 and the pair of tie rod arms 88 and 89.

Also, if such a low speed truck 70 attempts to turn to the right along the road, its steering wheel 32 will be rotated to the right, and with it,
Its front and rear power steering 11,12
Operates in the opposite manner to that described above, and in FIG. 6, steers its front wheels 75, 76 to the right and rear wheels 83, 84, 85, 86.
Steer to the left.

Especially when the truck 70 runs at low speed,
It is set to the opposite phase with respect to the front shaft turning angle, and when turning,
The truck 70 is steered to reduce the minimum turning radius (minimum turning radius), so that the truck 70
The turning performance is improved and parallel parking becomes much easier.

Furthermore, if the truck 70 is trying to turn along the road at high speed, then the control unit 29 in this case receives a signal from the speed sensor 66 to control the current flowing through the electric actuator 16. And drives its electric actuator 16, and as shown in FIG.
Through the reduction gear 56 and the pinion 57, the phase switching racks 14 and 15 are slid on the guide grooves 45 and 46 of the control beam 13, and accordingly, the movable rails 21 and
The movable rail sliders 23, 24 are slid onto the 22 and, at the same time, the control beam 13 moves the front wheels 75, 76.
Its fixed rail 1 which is swung around its pin 47 by its front power steering 11
The fixed rail sliders 19 and 20 are slid on 7 and 18, and the rear-axis steering angle and the rear-axis steering angle are in phase, and the rear-wheel steering angle with respect to the front-wheel steering angle is set to be generated. .

So if the truck 70 is trying to turn left along the road, its steering wheel
32 is rotated to the left.

As such, if the steering wheel 32 is rotated to the left, in the front power steering 11, the front control valve 31 is operated via its steering shaft 33, Pressure oil discharged from the hydraulic pump and adjusted in flow rate by the flow control valve is supplied to one cylinder chamber of the front booster 30, and pressure oil of the other cylinder chamber of the front booster 30 is also supplied. Is
It is returned to its oil reservoir.

As a result, in the front booster 30, the piston is slid from one cylinder chamber to the other cylinder chamber, and the sector gear meshed with the piston is rotated, so that the shaft of the sector gear is rotated. The pitman arm 35 fixed to 34 is swung backward in FIG.

As such, when the pitman arm 35 is swung backward, the drag link 36 is pushed backward by the pitman arm 35, and accordingly, the drag link 36 is rotatably supported by the front wheel shafts 73 and 74. The front wheel where it is being done 7
5,76 is steered leftward through its knuckle arm 37, tie rod 77, and tie rod arms 78,79.

As such, its front power steering 11
But when he steers its front wheels 75,76, the relay rod 4
8 is pushed backwards by its drag link 36, with its control beam 13 being swung backwards around its pin 47, in other words from the state shown in FIG. It is swung counterclockwise about its pin 47 and, at the same time, by its control unit 29, electric actuator 16, reduction gear 56, and pinion 57, its phase-shifting racks 14, 15, movable rail sliders 19, 20. However, since the fixed rails 17 and 18 are in the state shown in FIG. 5, the control beam 13, the phase switching racks 14 and 15, the fixed rails 17 and 18, the fixed rail
Sliders 19, 20, movable rails 21, 22, and movable rails
The sliders 23, 24 cooperate with each other to generate a rear wheel steering angle at which the rear wheel steering angle is in phase with the front wheel steering angle and which is related to the front wheel steering angle.

As such, when the control beam 13 is swung counterclockwise about its pin 47 in FIG. 1, the control cable 25, as shown in FIG. The inner cable 62 is pushed against the outer cable 60 and at the same time, in the control cable 26, the inner cable 63
Is pulled against the outer cable 61.

As such, as a result of the control cables 25, 26 being pushed and pulled, the rear control valve 39 has a spool shaft 43 connected to the inner cables 62, 63 that causes the spool to move to the valve body. Of the rear booster 38 is slid into the valve bore of the rear pump, discharged from the hydraulic pump, and flow-controlled by the flow control valve. The pressure oil supplied to the cylinder chamber and also in the other cylinder chamber of the rear booster 38 is returned to the oil reservoir via the rear return side hydraulic pipe.

As a result, in the rear booster 38, since the piston slides from one cylinder chamber to the other cylinder chamber,
Since the piston rod 41 is retracted into the cylinder body 40, the rear wheels 83, 84, 85, 86, which are rotatably supported by the rear wheel shafts 81, 82, are as shown in FIG. It is steered to the left through the tie rod 87 and a pair of tie rod arms 88 and 89.

Also, if such a high-speed truck 70 attempts to turn to the right along the road, its steering wheel 32 will be turned to the right, and with it,
Its front and rear power steering 11,12
Operates reversely to the case described above, and steers its front wheels 75, 76 and rear wheels 83, 84, 85, 86 to the right in FIG.

Especially when the truck 70 runs at high speed,
The turning angle is set to be smaller than the front shaft turning angle, and when the vehicle turns, the track 70 tends to be under-steered and the running stability is improved.

As will be apparent from the specific embodiments of the present invention described above with reference to the drawings, those having ordinary skill in the art to which the present invention pertains,
The subject matter of this invention is readily embodied in alternative forms which are derived from the nature and substance of the invention and which are objectively admitted to incorporate them. Of course, the content of the present invention is communsurate with the subject of the invention and is essential to the establishment of the invention.

Benefits of the Invention As can be understood from the above, the front and rear wheel steering system used in the automobile of the present invention includes a front steering that steers the front wheels, a rear power steering that steers the rear wheels, and the front steering thereof. And in relation to the rear power steering, it extends between the front and rear wheels in the left-right direction of the chassis and is rotatably supported on the chassis side, and in the front steering direction in the front-rear direction of the chassis. A swinging control beam, a pair of phase switching racks supported by the control beam so as to be able to reciprocate, an electric actuator that causes the control beam to reciprocate, and the rear of the control beam. At a predetermined distance to the left and right of the chassis, and the chassis A pair of fixed rails that extend in the front-rear direction and are fixed to the chassis side, a pair of fixed rail sliders that are fitted to the corresponding fixed rails, and in the left-right direction of the chassis behind the control beam. A pair of movable rails extended and fixed to the corresponding fixed rail sliders; and a pair of movable rail sliders fitted to the corresponding movable rails and rotatably connected to the corresponding phase switching racks. A pair of control cables connecting one end to its corresponding fixed rail slider and the other end to its rear power steering control valve, and its pair of phases to its electric actuator in response to the speed sensor signal. This includes a control unit that reciprocates the switching rack. The front and rear wheel steering system for use in an automobile, when the vehicle is traveling at a low speed, the rear wheel,
The steering angle of the rear axle is opposite to the steering angle of the front axle, and the steering angle of the rear wheel is related to the steering angle of the front wheel. As the front and rear wheels are steered in such a relationship, The minimum turning radius of the vehicle is reduced, the turning ability of the vehicle is improved, and parallel parking is greatly facilitated.When the vehicle is driven at high speed, the rear wheels are The vehicle is steered in the same phase with respect to the turning angle and at the rear wheel steering angle related to the front wheel steering angle, and in such a relationship, as the front wheels and the rear wheels are steered, the vehicle turns under When the vehicle is steered and the driving stability is improved, steering reliability is ensured even when the vehicle is driven at a low speed or at a high speed, and the vehicle speed and Its rear power steering in relation to the front power steering The steering performance of the steering wheel is improved, and in particular, the means for generating the steering input given to the rear power steering is simple and can be manufactured in a small size, and the device can be applied to various vehicle types. The pair of control cables, which are so-called versatile and which are means for transmitting steering input to the rear power steering, are flexibly bent according to the shape of the chassis of the car and are clipped to the chassis. Being attachable, the installation of the means for transmitting the steering input becomes very easy with it, thus avoiding the space constraint for installing the steering input transmitting means, and the steering input. Due to the mounting of the transmission means, the need for redesigning the vehicle is avoided, and as a result it is very useful and practical for the vehicle.

Further, the front and rear wheel steering system used in the automobile of the present invention has a front steering for steering the front wheels and a rear steering for steering the rear wheels having a control valve for centering the spool by either spring or fluid pressure. The power steering and its front and rear power steering in relation to its front and rear wheels, extending laterally of the chassis and rotatably supported on its side, and front·
A control beam that is swung in the front-rear direction of the chassis by steering, a pair of phase-switching racks that are reciprocally supported by the control beam, and electricity that causes the control beam to reciprocate. The actuator and a pair of fixed rails which are arranged behind the control beam at a predetermined distance in the left-right direction of the chassis and extend in the front-rear direction of the chassis and are fixed to the chassis side, and the corresponding rails. A pair of fixed rail sliders fitted to the fixed rails, a pair of movable rails extending in the left-right direction of the chassis behind the control beam and fixed to the corresponding fixed rail sliders, and their corresponding It is fitted to a movable rail and turned to its corresponding phase switching rack. Possible and a pair of movable rail slider coupled to the safety cable to be broken at least a predetermined tensile load using at least a portion, and, at one end to the fixed rail sliders its corresponding, the rear and the other end
Since a pair of control cables respectively connected to the control valves of the power steering and a control unit for causing the electric actuator to reciprocate the pair of phase switching racks in response to the signal of the vehicle speed sensor are included, In the front and rear wheel steering system used in automobiles, the rear wheels are
The steering angle of the rear axle is opposite to the steering angle of the front axle, and the steering angle of the rear wheel is related to the steering angle of the front wheel. As the front and rear wheels are steered in such a relationship, The minimum turning radius of the vehicle is reduced, the turning ability of the vehicle is improved, and parallel parking is greatly facilitated.When the vehicle is driven at high speed, the rear wheels are The vehicle is steered in the same phase with respect to the turning angle and at the rear wheel steering angle related to the front wheel steering angle, and in such a relationship, as the front wheels and the rear wheels are steered, the vehicle turns under When the vehicle is steered and the driving stability is improved, steering reliability is ensured even when the vehicle is driven at a low speed or at a high speed, and the vehicle speed and Its rear power steering in relation to the front power steering The steering performance of the steering wheel is improved, and in particular, the means for generating the steering input given to the rear power steering is simple and can be manufactured in a small size, and the device can be applied to various vehicle types. The pair of control cables, which are so-called versatile and which are means for transmitting steering input to the rear power steering, are flexibly bent according to the shape of the chassis of the car and are clipped to the chassis. Being attachable, the installation of the means for transmitting the steering input becomes very easy with it, thus avoiding the space constraint for installing the steering input transmitting means, and the steering input. Due to the mounting of the transmission means, it is possible to avoid the need to change the design of the vehicle. When excessive force is applied, the safety cable is broken, the spool is moved to the neutral position at the rear control valve, the rear power steering is operated fail-safe, and the rear wheels are in the straight running state. Is maintained, and thus the safety of the vehicle in driving is ensured, so that it is very useful and practical for the vehicle.

[Brief description of drawings]

FIG. 1 is a schematic view of a front / rear wheel steering system used in an automobile of the present invention applied to a truck, and FIG. 2 is a partial perspective view of a control beam used in the front / rear wheel steering system shown in FIG. 3 and FIG. 3 are perspective views of means for generating steering input of the rear power steering used in the front and rear wheel steering system shown in FIG. 1, and FIG. 4 is a rear view thereof when the truck is running at low speed.・ A schematic diagram of means for generating steering input of power steering, Fig. 5 is a schematic diagram of means for generating steering input of the rear power steering of the truck at high speed traveling, and Fig. 6 is low speed traveling At that time, the wheel state diagram of the truck, and FIG.
It is a wheel state diagram of the truck. 11 …… Front steering, 12 …… Rear power
Steering, 13 ... Control beam, 14, 15 ...
… Phase switching rack, 16 …… Electric actuator, 17,1
8 …… Fixed rail, 19,20 …… Fixed rail / slider, 2
1,22 …… Movable rail, 23,24 …… Movable rail slider, 25,26 …… Control cable, 27,28 …… Safety cable, 29 …… Control unit.

Claims (2)

[Claims] 1. A front steering for steering front wheels, a rear power steering for steering rear wheels, and a chassis between the front and rear wheels in relation to the front steering and rear power steering. Of the control beam, which is extended in the left-right direction of the chassis and is rotatably supported on the chassis side, and is reciprocally supported by the control beam that is swung in the front-rear direction of the chassis by the front steering. A pair of phase-shifting racks, an electric actuator that reciprocates the phase-shifting racks in the control beam, a predetermined distance in the left and right direction of the chassis behind the control beam, and the front and rear of the chassis. A pair of fixed rails that are extended in the direction and fixed to the chassis side, A pair of fixed rail sliders fitted to the corresponding fixed rails, and a pair of movable rails that are extended in the left and right direction of the chassis behind the control beam and fixed to the corresponding fixed rail sliders. A pair of movable rail sliders fitted to their corresponding movable rails and rotatably coupled to their corresponding phase-shifting racks, one end of which is the corresponding fixed rail slider and the other end of which is the rear power steering. Front and rear wheel steering used in a vehicle including a pair of control cables respectively connected to the control valves of the vehicle and a control unit that causes the electric actuator to reciprocate the pair of phase switching racks in response to a signal from the vehicle speed sensor. system. 2. A front power steering for steering front wheels, a rear power steering for steering rear wheels having a control valve for centering a spool by either spring or fluid pressure, and front steering In relation to the rear power steering, it extends between the front and rear wheels in the left-right direction of the chassis and is rotatably supported on the chassis side, and its front steering oscillates in the front-back direction of the chassis. A control beam to be moved, a pair of phase switching racks supported by the control beam so as to reciprocate, an electric actuator for reciprocating the phase switching rack to the control beam, and the rear of the control beam. At the left and right sides of the chassis Then, a pair of fixed rails extending in the front-rear direction of the chassis and fixed to the chassis side, a pair of fixed rail sliders fitted to the corresponding fixed rails, and the chassis behind the control beam. A pair of movable rails that are extended in the left-right direction and fixed to the corresponding fixed rails and sliders, and a pair of movable rails that are fitted to the corresponding movable rails and are rotatably connected to the corresponding phase switching racks. Use a rail slider and a safety cable that breaks above a given tensile load, at least in part, and use one end for its corresponding fixed rail slider and the other end for its rear power steering control valve. Depending on the signal from the speed sensor, a pair of control cables connected to each Front and rear wheel steering system for use of the pair of phase switching rack care actuator in a vehicle including a control unit for reciprocating.