JPH0729616B2 - 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 rear wheels and front 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 is coupled to the steering and via its linkage a steering input is applied to the rear power steering, and so the rear power steering is related to the steering of the front power steering. Can be steered.

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.

An object of the present invention is to ensure reliability, enable steering input to be transmitted from front steering to rear power steering by a simple means, and steer rear wheels in relation to steering front wheels. A means for transmitting a steering input is to provide a front and rear wheel steering system for use in a vehicle that is easily arranged without being restricted in space.

Another object of the present invention is to provide a fail-safe operation of the rear power steering when a failure occurs in a means for transmitting a steering input, thereby ensuring reliability and safety in running the vehicle. It is to provide the front and rear wheel steering system used for the.

SUMMARY OF THE INVENTION FOR PROBLEM TO BE SOLVED BY THE INVENTION In relation to the above-mentioned problems, a front and rear wheel steering system used in a vehicle according to the present invention is a front steering for steering front wheels supported on a chassis side, and a chassis thereof. Rear power steering that steers the rear wheels supported on the side, and in relation to the front steering and rear power steering, can swing forward and backward between the front and rear wheels to the chassis side The control beam supported by and one end to the beam end of the control beam,
A pair of control cables that connect the other end to the control valve of the rear power steering, respectively, and an appropriate space in front of the control beam, supported on the chassis side so that it can be swung back and forth. , And a phase switching beam that is swung by the front steering, and a phase switching rack that is supported by the phase switching beam so as to be capable of reciprocating in the beam length direction,
An electric actuator that reciprocates the phase-switching rack to the phase-switching beam, a fixed rail extending in the front-rear direction and fixedly arranged on the chassis side in at least the swing range of the control beam, and the fixed rail. A fixed rail slider slidably fitted to the control beam and rotatably connected to the control beam; and a movable rail that extends in a direction orthogonal to the fixed rail and is fixedly supported by the fixed rail slider. A rail, a movable rail slider slidably fitted to the movable rail and rotatably coupled to the phase-shifting rack, and a control unit for driving the electric actuator according to a vehicle speed, and , Its control unit drives its electric actuator depending on the vehicle speed , The phase switching rack the electric actuator is moved to the phase switching beam to determine the steering angle and the phase of the subsequent wheels associated with the front wheels,
Rock the control beam accordingly,
The control valve of the rear power steering is operated via the control cable, and the rear power steering is driven to steer the front and rear wheels.

Further, the front and rear wheel steering system used in the vehicle of the present invention has the above-mentioned configuration, and the pair of control cables is formed at the loop ends connecting the one ends to each other and supported by the control beam. , And then
Connect the other end to its rear power steering control valve, and an equalizer with a spring biased against the loop end of that control cable to even out the tension applied to that control cable. After all, the control valve of the rear power steering is operating smoothly.

Further, the front and rear wheel steering system used in the vehicle of the present invention has the above-mentioned configuration, and the rear power steering has a control valve for centering the spool by either spring or fluid pressure, The pair of control cables has a structure in which one end is connected to each other with a safety cable that is broken under a predetermined tensile load or more to form a loop end, and the phase and steering angle are set to the control valve. When an unreasonable force is applied to the transmission means, the control cable is broken at the safety cable, and at the control valve, the spool is moved to the neutral position, so-called centering, and the rear power It is about to operate the steering wheel fail-safe.

Description of specific examples Hereinafter, specific examples of the front and rear wheel steering systems used in the vehicle of the present invention will be described with reference to the drawings.

1 to 5 show a tenth embodiment of the front and rear wheel steering system used in the automobile of the present invention applied to a truck 80.

The front and rear wheel steering system 10 includes front wheels supported on the chassis 81 side.
A front steering wheel 11 that steers 85 and 86, and a rear control valve 36 that centers a spool (not shown) with a spring (not shown), and rear wheels 93 that are supported on the chassis 81 side, Rear steering 94,95,96
Power steering 12 and control beam 13
And a pair of control cables 14, 15 formed at the loop end 17 by connecting one end to each other with a safety cable 16.
And an equalizer attached to the loop end 17
18, a phase switching beam 19, a phase switching rack 20,
An electric actuator 21, a fixed rail 22, a fixed rail slider 23, a movable rail 24, a movable rail slider 25, and a control unit 26,
Its front steering 11 enables its front wheels 85,86 to be steered, and at the same time its rear power steering 12 relates to the steering angle and vehicle speed of its front wheels 85,86.
The rear wheels 93, 94, 95, 96 are steerable. further,
To specifically describe the steering of the rear wheels 93, 94, 95, 96 related to the vehicle speed, the rear power steering 12 is:
The angle of the rear axle 90 (the angle of the rear axle) with respect to the angle of the front axle 82 (the angle of the front wheels) is reversed, and the track 80
When the vehicle is traveling at high speed, the rear wheels 93, 94, 95, 96 are steered in the same phase as the rear shaft cutting angle with respect to the front shaft cutting angle.

The front steering 11 is a front booster
27, front control valve 28, hydraulic pump (not shown), flow control valve (not shown), steering wheel 29, steering shaft 30, pitman arm 32, drag link 33,
And a knuckle arm 34, configured for power steering.

Also, in this front power steering 11, its front booster 27, front control valve 28, 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 27 incorporates the front control valve 28 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 31 is meshed with the piston to transfer the force and movement of the piston to the pitman arm 32.

As such, its front booster 27, which was built as a normal integral type, is also the chassis of its truck 80.
A front axle 82 disposed in front of 81 is swingably connected to both ends of a front axle 82 via a knuckle and a king pin, and its front wheel 8
A pair of front wheel shafts 83 and 84 that rotatably support 5,86 respectively.
To the pitman arm 32, the drag link 33, and the knuckle arm 34. Of course, the front wheel shafts 83, 84 are connected to each other by a tie rod 87 and a pair of tie rod arms 88, 89.

The front control valve 28 is manufactured in the same manner as a control valve for a normal integral type power steering, and is also gear-coupled to the steering shaft 30 through the steering shaft 30. It is operated by the steering wheel 29. Of course, this front control valve 28
Is operated by the steering wheel 29, the pressure oil discharged from the hydraulic pump and the flow rate of which is adjusted by the flow control valve is selectively supplied to the pair of cylinder chambers of the front booster 11. At the same time, the pressure oil in the pair of cylinder chambers of the front booster 11 is selectively returned to the 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
Manufactured similarly to 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 28, and also in the front booster bypass. Is connected to the front return hydraulic line. Of course, this flow control valve adjusts the flow rate of the pressure oil supplied from the hydraulic pump so that the pressure oil of a predetermined flow rate is supplied to the front booster 27 and the rear valve.
It feeds booster 35 and also returns the 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 35 and rear control valve 36 are attached to them, the rear supply side hydraulic piping (not shown) and the rear return. It is configured by connecting side hydraulic piping (not shown), the cylinder body 37 of the rear booster 35 is pivotally connected to the tie rod arm 99, and the piston rod 38 of the rear booster 35 is connected. After that, it is pivotally connected to the axle 90 via the bracket 40, then pivotally connected to both ends of the axle 90, and the pair of rear wheel axles 91, 94 rotatably supported by the rear wheels 93, 94, 95, 96. 92 for tie rod 9
It is steerable via 7 and a pair of tie rod arms 98,99.

Further, in the rear power steering 12, the rear control valve 36 is incorporated in the cylinder body 37 of the rear booster 35.

The rear control valve 36, as described above, has its spool manufactured in a structure centered by the spring, and in the state where no steering input is applied, in the rear booster 35, A piston (not shown) is held in a neutral position within the cylinder bore of the cylinder body 37. That is, the rear control valve 36 operates the rear power steering 12 in a fail-safe manner to make the truck 80 safe for traveling. Of course, the rear control valve 36 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 13 is its front power steering 11 and rear power steering 12
Rotatably fitted to a pin 43 of a bracket (not shown) screwed to its chassis 81 between its front wheels 85,86 and rear wheels 93,94,95,96 in relation to The chassis 81 is supported so as to be swingable in the front-rear direction.

Further, the control beam 13 has cable connection holes 41 and 42 formed at both beam ends, and the loop end 17 which is one end of the pair of control cables 14 and 15 is connected to the cable connection holes 41 and 42. Through.

As such, the control beam 13 where the control cables 14 and 15 are connected has the rear power steering angle and the rear wheel phase determined by the phase switching beam 19 and the phase switching rack 20 changed to the rear power. -Transmission to the rear control valve 36 of the steering 12 via its control cables 14,15.

The pair of control cables 14 and 15 are ordinary push-pull cables, which are composed of outer cables 44 and 45 and inner cables 46 and 47, and one end of the inner cables 46 and 47 is connected to the control cables. The cables 13 are connected to each other by the safety cable 16 passed through the cable connection holes 41 and 42 of the beam 13, and the other ends of the inner cables 46 and 47 are connected to the spool shaft 39 of the rear control valve 36. The movement of the control beam 13, that is, the rear wheel steering angle and the rear wheel phase can be transmitted to the rear control valve 36.

The safety cable 16 is, of course, the inner cable 4
Designed to a predetermined tensile load, which is predetermined to a value smaller than the tensile load of the inner cable 46,47 when the 6,47 is broken, the rear wheel steering angle and rear wheel phase When an unreasonable force is applied to the steering angle transmitting means which transmits to the control valve 36, in other words, when a force equal to or larger than the predetermined tensile load is applied, the safety cable 16 is broken, It interrupts the transmission of steering angle and phase, so that at its rear control valve 36, a spool (not shown) is moved to a neutral position by a spring (not shown),
The rear power steering 12 is moved to fail safe.

As such, this safety cable 16 prevents steering of the rear wheels 93, 94, 95, 96 by its rear power steering 12 in the event of failure of its steering angle transmission means,
The safety of the truck 80 is ensured during driving.

On the other hand, the outer cables 44, 45 are clipped to the chassis 81 in the middle at appropriate positions.
Of course, the outer cables 44, 45 may be bolted to the chassis 81, or by any other suitable means.

Further, the pair of control cables 14 and 15 includes screw rods 48 and 49 at one end of the inner cables 46 and 47,
Adjusting nuts 50 and 51 and lock nuts 52 and 53 are screwed to the threaded rods 48 and 49, and the control beam 13
The cable length between the rear control valve 36 and the rear control valve 36 is adjustable. That is, loosen the lock nuts 52, 53 and place the adjusting nut 5 on the threaded rods 48, 49.
If you move 0,51 and tighten the lock nuts 52,53 again, the control cables 14,15 will
The cable length between its control beam 13 and its rear control valve 36 is easily adjusted.

In the pair of control cables 14 and 15, the safety cable 16 is connected between the screw rods 48 and 49 to form a loop end 17. Of course, that safety cable
16 is the cable connecting hole 41, 4 of the control beam 13
Since it is threaded through 2, the pair of control cables 14, 15 is connected to its control beam 13 in cooperation with an equalizer 18 and a compression spring 54, which will be described later, and thus its It is supported by the control beam 13.

The equalizer 18 is manufactured in a substantially semicircular plate, a cable groove 55 is formed on the outer peripheral surface of the plate, the safety cable 16 is fitted in the cable groove, and the loop ends of the control cables 14 and 15 are formed. It is attached to 17. Of course, the equalizer 18 is pressed against the loop end 17 by the compression spring 54 and is prevented from coming off the loop end 17.

As such, its equalizer 18, which is snapped onto its loop end 17 by its compression spring 54, equalizes the tension on its control cables 14,15. Of course, the equalizer 18 may be manufactured in a circular plate.

The compression spring 54 has one end connected to the pin 56 of the equalizer 18 and the other end to the pin 43 for the control beam 13,
18 is pressed against the loop ends 17 of the control cables 14,15.

The phase switching beam 19 is the control beam
It is swingably supported in the front-rear direction on the chassis 81 side at an appropriate interval in front of 13, and is swung by the front power steering 11. In particular, this phase switching beam 19 is manufactured in the shape of an elongated box so as to reciprocally support the phase switching rack 20.

More specifically, the phase switching beam 19 is provided with a slit 57 on the bottom wall extending in the beam length direction, and is screwed to the chassis 81 in a set state in which both ends are directed to both sides of the chassis 81. It is rotatably supported by a pin 58 of a fixed bracket (not shown). Of course, this phase-switching beam 19 is connected to its front power steering 11 via a pivoted relay rod 59.
The front wheel steering angle, which is connected to the drag link 33 of the vehicle and transmitted through the relay rod 59 thereof, that is, the steering of the front power steering 11 causes the swinging around the pin 58 in the horizontal plane. Be moved.

In particular, the relay rod 59, as shown in FIG.
The displaceable amount of the connecting portion is the drag link 33.
If the load is smaller than the position amount of the
The structure is such that it is absorbed by and transmitted to the phase switching beam 19.

Further, as understood from FIG. 2, the phase switching beam 19 has the phase switching rack 20 fitted therein so as to be reciprocally movable in the beam length direction, and the phase switching rack 19 is
It was built into a structure that supports 20.

As can be seen from FIG. 2, the phase-shifting rack 20 reciprocally slides in the phase-shifting beam 19 on the bottom wall of the phase-shifting beam 19 in the beam length direction with the tooth surface 60 facing upward. It is movably arranged.

The phase switching rack 20 has an arm 61 screwed to the lower surface at a predetermined position. Of course, the arm 61 is made to project to the outside through the slit 57 of the phase switching beam 19 and the tip side thereof is set to the phase switching beam 19.
It extends to the front of.

The arm 61 has its fixed rail slider 23 fitted to its fixed rail 22, as will be described in detail later.
Movable rail 2 fixed to the fixed rail slider 23
4, and the movable rail slider 25 fitted to the movable rail 24 is interposed and connected to the control beam 13.

The electric actuator 21 is a stepping motor, and the phase switching rack 20 is connected via a reduction gear mechanism.
In the phase switching beam 19, the phase switching rack 20 is mounted on the bottom wall of the phase switching beam 19.
Slide back and forth.

In this electric actuator 21, a motor shaft 63 supporting a rotor (not shown) has a predetermined rotation center of the phase switching beam 19, that is, a predetermined rotation axis (C), as shown in FIG. Crossed at right angles at intervals, the motor housing 62 is screwed onto its phase switching beam 19 and a stator (not shown) is placed within the motor housing 62 around its rotor. , The stator winding (not shown) is electrically connected to the output circuit of the control unit 29.

As such, its electric actuator 21 assembled to its phase-switching beam 19 also fixes its rotor to a motor shaft 63 with a motor gear 64, through its reduction gear mechanism to its phase-shifting rack. It is possible to transmit power to 20.

The reduction gear mechanism includes a reduction gear 65 meshed with the motor / gear 64, a pinion 66 meshed with the phase switching rack 20, and the reduction gear 65 and the pinion 66 connected to each other. The shaft 67 is configured to support the reduction gear 65 and the pinion 66.

Particularly, in this reduction gear mechanism, the pinion 66 is engaged with the phase switching rack 20 in a direction orthogonal to the rotation axis (C) of the phase switching beam 19 with the axis line of the shaft 67 at a predetermined interval. Aligned.

The fixed rail 22 is extended and arranged in the front-rear direction of the chassis 81 in relation to the control beam 13 and the phase switching beam 19, and is fixed to a bracket 68 of the chassis 81.

In particular, the fixed rail 22 has a length determined in relation to the swing range of the control beam 13, which is swung around the pin 43, specifically, the front-back movement range of the chassis 81. To be done.

The fixed rail slider 23 is slidably fitted to the fixed rail 22 and includes an arm 69, and the tip of the arm 69 is attached to the control beam 13.
Is rotatably connected to the pin via a pin 70.

The movable rail 24 extends in the right-left direction in the chassis 81 in a direction orthogonal to the fixed rail 22, is fixed to the fixed rail slider 23, and is moved on the fixed rail 22. And is supported by the fixed rail slider 23.

The movable rail 24 also has a length determined in relation to the swing range of the control beam 13 swung around the pin 43, specifically, the horizontal movement range of the chassis 81. To be done.

The movable rail slider 25 is slidably fitted to the movable rail 24 and is supported by the movable rail 24.

The movable rail / slider 25 is rotatably connected to the tip of an arm 61 of the phase switching rack 20 via a pin 71, and is moved on the movable rail 24 along with the movement of the phase switching rack 20. Be slid on.

The control unit 26 includes an input / output circuit, a memory circuit, an arithmetic circuit, a control circuit, a power supply circuit, and the like,
The memory circuit determines the vehicle speed and the front wheel steering angle, the so-called steering direction of the front power steering 11, the steering speed, and the rear wheel steering angle with respect to the steering amount, in other words, the vehicle speed. A program for relatedly determining the rear-axis cutting angle with respect to the front-axis cutting angle is stored in advance, and the program is operated according to the signal input from the vehicle speed sensor 72, and the electric actuator
It was configured to control the pulse current (electrical pulse) flowing through 21.

That is, the control unit 26 calculates by the program according to the signal from the vehicle speed sensor 72, controls the pulse current (electrical pulse) flowing through the stator winding of the stepping motor 21, and reduces the speed. Gear mechanism
The stepping motor 21 via 65, 66, 67 moves the phase-shifting rack 20 into the phase-shifting beam 19 and thus determines the rear-wheel steering angle relative to the front-wheel steering angle in relation to the vehicle speed. Then, by the rear wheel steering angle, specifically, allow the rocking of the control beam 13 around the pin 43 at a rotation angle corresponding to the rear wheel steering angle,
The rear power steering 12 has a rear-axis steering angle in reverse phase with respect to the front-axis steering angle, or a rear-axis steering angle with respect to the front-axis steering angle in the same phase, and rear wheels 93,94,95, It's about making the 96 steerable.

The vehicle speed sensor 72 detects the traveling speed of the truck 80, and is arranged on the output shaft of a transmission (not shown) mounted on the truck 80.

Next, when the truck 80 travels, steering by the front and rear wheel steering system 10 manufactured as described above will be described.
If the truck 80 is driven at low speed on a straight road, the hydraulic pump is driven by the diesel engine, so the pressure oil expelled from the hydraulic pump is at the flow control valve. The flow rate is adjusted so that a predetermined flow rate of pressure oil flows to the front and rear supply side hydraulic pipes and is sent to the front and rear control valves 28 and 36.

Then, 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 27, 35, respectively. The piston is held in the neutral position.

On the other hand, the control unit 26 inputs a signal from the vehicle speed sensor 72, controls a pulse current (electric pulse) flowing through the electric actuator 21, drives the electric actuator 21, and is shown in FIG. As can be seen from the combination, via its reduction gear 65 and pinion 66 fixedly connected to each other by its shaft 67,
The electric actuator 21 slides the phase switching rack 20 on the phase switching beam 19, and accordingly, the movable rail slider 25 is mounted on the movable rail 24.
On the fixed rail 22, slide the fixed rail slider 23 and the movable rail 24, respectively, and at the same time,
The phase switching beam 19 is in a state of being swung around its pin 58 by the front power steering 11 which steers its front wheels 85, 86, and its control beam 13 is also swung to its pin 43. Being pos- sibly supported, its control beam 13 is oscillated around its pin 43 to generate a rear-wheel steering angle with respect to the front-wheel steering angle in antiphase with respect to the front-axis steering angle. It is located in

From such a running condition, if the truck 80 attempts to turn left along the road at low speed, as shown in FIG. 4, the steering wheel 29 will be turned left.

As such, if the steering wheel 29 is rotated to the left, in the front power steering 11, the front control valve 28 is operated via its steering shaft 30, The 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 27, and the pressure oil of the other cylinder chamber of the front booster 27 is also supplied. Is returned to the oil reservoir.

As a result, in the front booster 27, the piston slides from one cylinder chamber to the other cylinder chamber, and the sector gear meshed with the rack of the piston is rotated. The pitman arm 32 fixed to 31 is swung backward in FIG.

As such, when the pitman arm 32 is swung rearward, the drag link 33 is pushed backward by the pitman arm 32, and accordingly, the drag link 33 is rotatably supported by the front wheel shafts 83, 84. The front wheel where it is being done 8
5,86 is steered to the left via its knuckle arm 34, tie rod 87, and tie rod arms 88,89.

As such, its front power steering 11
But when he steers its front wheels 85,86, the relay rod 5
9 is pushed backwards by its drag link 33, with which its phase-switching beam 19 is swung backwards around its pin, in other words from the state shown in FIG. The control unit 26 swings clockwise around the pin 58, and at the same time, the control unit 26 controls the pulse current (electric pulse) flowing through the electric actuator 21 in response to the signal of the vehicle speed sensor 72, and the electric actuator 21 and slides its phase-shifting rack 20 into its phase-switching beam 19 by means of its electric actuator 21 via its speed-reduction gear mechanism, from the state shown in FIG. Since the movable rail / slider 23 is moved to the right side over the rotation axis (C), the phase switching beam 19, the phase switching rack 20, and the fixed rail 22 are moved. , Fixed rails and sliders
23, movable rail 24, movable rail slider 25, and
The control beams 13 cooperate with each other to make the rear-axis cutting angle with respect to the front-axis cutting angle antiphase, and
Generate a rear wheel steering angle that is related to the front wheel steering angle.

As such, when the phase-switching beam 19 is swung counterclockwise about its pin 58 in FIG.
The control beam 13 is shown in FIG.
Swung counterclockwise about 43, in its control cable 15, its inner cable 47 is pulled against its outer cable 45, while at the same time its inner cable 47 is attached to its equalizer 18. In the control cable 14, the inner cable 46 is connected to the inner cable 46 of the control cable 15 by the supported safety cable 16 thereof.
Is pressed against the outer cable 44.

As such, as a result of the control cables 14,15 being pushed and pulled, the rear control valve 36 has a spool shaft 39 connected to its inner cables 46,47 that causes the spool to move to the valve body. Of the rear booster 35 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 (not shown) and in one cylinder chamber (not shown) of the rear booster 35 is returned to the oil reservoir via the rear return side hydraulic pipe.

As a result, in the rear booster 35, since the piston slides from the other cylinder chamber to the one cylinder chamber,
Since the piston rod 38 is pushed out of the cylinder body 37, the rear wheels 93, 94, 95, 96, which are rotatably supported by the rear wheel shafts 91, 92, are as shown in FIG. , Its tie rod 97, and a pair of tie rods
Steered to the right via rod arms 98,99.

Also, if such a low speed truck 80 attempts to turn to the right along the road, its steering wheel 29 will be rotated to the right, and with it,
Its front and rear power steering 11,12
Operates reversely to the above-mentioned case, and in FIG. 4, steers its front wheels 85, 86 to the right and rear wheels 93, 94, 95, 96.
Steer to the left.

Especially when the truck 80 runs at low speed,
It is set to the opposite phase with respect to the front shaft turning angle, and when turning,
The truck 80 is steered to reduce the minimum turning radius (minimum turning radius), so that the truck 80
The turning performance is improved and parallel parking becomes very easy.

Further, if the truck 80 is trying to turn along the road at high speed, then the control unit 26, in this case, responds to the signal of the vehicle speed sensor 72 with a pulsed current ( Electric pulse)
Control the electric actuator 21, and drive the electric actuator 21 through the reduction gear mechanism.
21 the phase switching rack 20 and the phase switching beam 19
In the state shown in FIG. 2 by sliding it inside, in other words, in FIG. 2, the movable rail in a state of being moved to the left beyond the rotation axis (C) of the phase switching beam 19 in FIG. Since the slider 25 is moved, its phase switching beam 19, phase switching rack 20, fixed rail 22, fixed rail slider 23, movable rail 24, movable rail slider 2
5, and the control beam 13 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 is related to the front wheel steering angle.

Now, if the truck 80 wants to turn left along the road, its steering wheel 29 is turned left.

As such, if the steering wheel 29 is rotated to the left, in the front power steering 11, the front control valve 28 is operated via its steering shaft 30, The 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 27, and the pressure oil of the other cylinder chamber of the front booster 27 is also supplied. Is
It is returned to its oil reservoir.

As a result, in the front booster 27, the piston slides from one cylinder chamber to the other cylinder chamber, and the sector gear meshed with the rack of the piston is rotated. The pitman arm 32 fixed to 31 is swung backward in FIG.

As such, when the pitman arm 32 is swung rearward, the drag link 33 is pushed backward by the pitman arm 32, and accordingly, the drag link 33 is rotatably supported by the front wheel shafts 83, 84. The front wheel where it is being done 8
5,86 is steered leftward through its knuckle arm 34, tie rod 82, and tie rod arms 83,84.

As such, its front power steering 11
But when he steers its front wheels 85,86, the relay rod 5
9 is pushed backwards by its drag link 33, with which its phase switching beam 19 is swung counterclockwise around its pin 58 in FIG. 1 and its control beam 13 Is the pin 43 in FIG.
Is swung clockwise around.

Therefore, in the control cable 15, the inner cable 47 is replaced by the outer cable 45.
Is pressed against the inner cable 47 at the same time,
Since the safety cable 16 supported by the equalizer 18 is connected to the inner cable 46 of the control cable 14, in the control cable 14, the inner cable 46 is different from the outer cable 44. Be drawn.

As such, as a result of the control cables 14,15 being pushed and pulled, the rear control valve 36 has a spool shaft 39 connected to its inner cables 46,47 that causes the spool to move to the valve body. Of the rear booster 35 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 the pressure oil in the other cylinder chamber of the rear booster 35 is returned to the oil reservoir through the rear return side hydraulic pipe.

As a result, in the rear booster 35, the piston slides from one cylinder chamber to the other cylinder chamber,
Since the piston rod 38 is retracted into the cylinder body 37, the rear wheels 93, 94, 95, 96, which are rotatably supported by the rear wheel shafts 91, 92, are as shown in FIG. It is steered to the left through the tie rod 97 and a pair of tie rod arms 98 and 99.

If the truck 80 traveling at such a high speed tries to turn to the right along the road, the steering wheel 29 thereof is rotated to the right, and accordingly,
Its front and rear power steering 11,12
Operates reversely to the case described above, and steers the front wheels 85, 86 and the rear wheels 93, 94, 95, 96 to the right in FIG.

Especially when the truck 80 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 80 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 contents of the present invention are commensurate with the subject of the invention and are essential to the establishment of the invention.

Benefits of the Invention As will be understood from the above, the front-rear wheel steering system used in the vehicle of the present invention comprises the front steering for steering the front wheels supported on the chassis side and the rear wheels supported on the chassis side. Rear power steering to steer,
In relation to the front steering and the rear power steering, a control beam, which is swingably supported in the front-rear direction on the chassis side between the front wheels and rear wheels, and one end thereof is a beam end of the control beam. And a pair of control valves that connect the other end to the control valve of the rear power steering.
A cable and a phase switching beam that is oscillated in the front-rear direction on the chassis side at an appropriate distance in front of the control beam and is oscillated by the front steering, and the phase switching beam. A phase switching rack that is reciprocally supported in the beam length direction, an electric actuator that reciprocates the phase switching rack to and from the phase switching beam, and front and rear on the chassis side at least in the swing range of the control beam. Fixed rail that is extended in the direction and fixedly arranged,
A fixed rail that is slidably fitted to the fixed rail and rotatably connected to the control beam.
A slider, a movable rail extending in a direction orthogonal to the fixed rail and fixedly supported by the fixed rail / slider, and slidably fitted to the movable rail so as to be rotatable on the phase switching rack. Since the movable rail slider to be coupled and the control unit that drives the electric actuator according to the vehicle speed are included, in the front and rear wheel steering system used in the vehicle of the present invention, when the vehicle travels at a low speed, The rear wheels are steered at a rear-axis steering angle that is opposite to the front-axis steering angle, and at a rear-wheel steering angle that is related to the front-wheel steering angle. As a result, the minimum turning radius of the vehicle is reduced, the turning performance of the vehicle is improved, parallel parking becomes very easy, and when the vehicle is traveling at high speed, the rear wheels have a rear axle turning angle. Front axis The steering wheel is steered in the same phase with respect to the steering angle, and at the rear wheel steering angle related to the front wheel steering angle. 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 and at a high speed, and the vehicle speed and Since steering is performed in relation to the front steering, the steerability of the rear power steering is improved, and in particular, the means for generating steering input given to the rear power steering can be easily manufactured, Is applicable to various vehicle types, is so-called versatile, and on top of that, the chassis of the pair of control cables is a means for transmitting steering input to the rear power steering. It can be flexibly bent to its shape and can be attached to its chassis with a clip, so that the means for transmitting its steering input is very easy to attach, and thus its steering input transmitting means is attached. Freed from space constraints, the need to redesign the vehicle is avoided due to the mounting of the steering input transmission means.

Further, the front and rear wheel steering system used in the vehicle of the present invention has the above-mentioned configuration, and the pair of control cables is formed at the loop ends connecting the one ends to each other and supported by the control beam. , And then
The other end is connected to the control valve of the rear power steering, and the equalizer is configured to be pressed by the spring to the loop end of the control cable, so that it is used before and after the vehicle of this invention is used. In the wheel steering system, the tension applied to the control cable is equalized, the rear control valve operates smoothly, and the characteristics of the rear power steering are improved.

Further, the front and rear wheel steering system used in the vehicle of the present invention has the above-mentioned structure, and one end of the pair of control cables is connected to each other by a safety cable that is broken by a predetermined tensile load or more. Is formed at the loop end, and its rear control valve is constituted by centering the spool by either spring or fluid pressure, so in the front and rear wheel steering system used in the automobile of the present invention, When an unreasonable force is applied to the steering input transmission means, in other words, the steering angle transmission means, the safety cable is broken, the spool is moved to the neutral position at the rear control valve, and the rear The power steering is fail-safe and the rear wheels are kept straight, thus Safety is ensured in a very useful and practical for automobiles.

[Brief description of drawings]

FIG. 1 is a schematic view of a front and rear wheel steering system used in a vehicle of the present invention applied to a truck, and FIG. 2 is a control beam used in the front and rear wheel steering system shown in FIG. Control cable, equalizer, phase switching beam, phase switching rack, electric actuator, fixed rail, fixed rail slider, movable rail,
And an enlarged perspective view of the movable rail slider, FIG.
FIG. 4 is a sectional view in the axial direction showing the structure of the rod end of the drag link connected to the phase switching beam shown in FIG. 2, FIG. 4 is a wheel state diagram of a truck during low speed traveling, and FIG. The figure is a wheel state diagram of a truck when traveling at high speed. 11 ... Front power steering, 12 ... Rear power steering, 13 ... Control beam, 14,15
… A pair of control cables, 16… Safety cables,
17 ... Loop end, 18 ... Equalizer, 19 ... Phase switching beam, 20 ... Phase switching rack, 21 ... Electric actuator, 22 ... Fixed rail, 23 ... Fixed rail slider, 24 ...
Movable rail, 25 ... Movable rail slider, 26 ... Control unit.

Claims (3)

[Claims] 1. A front steering for steering front wheels supported on a chassis side, a rear power steering for steering rear wheels supported on the chassis, and a front steering and a rear power steering thereof. Relatedly, a control beam is supported between the front and rear wheels on the chassis side so as to be swingable in the front-rear direction, and one end is the beam end of the control beam and the other end is the rear power A pair of control cables that connect to the steering control valves, and a front and rear control beams that are supported on the chassis side so that they can be swung back and forth at appropriate intervals. A pulsating phase-switching beam and reciprocating movement in the beam length direction for the phase-switching beam A supported phase switching rack, an electric actuator for reciprocating the phase switching rack with respect to the phase switching beam, and a fixed arrangement extending in the front-rear direction on the chassis side at least in the swing range of the control beam. Fixed rail that is slidably fitted to the fixed rail and rotatably connected to the control beam.
A slider, a movable rail extending in a direction orthogonal to the fixed rail and fixedly supported by the fixed rail / slider, slidably fitted to the movable rail, and rotatable on the phase switching rack. A front / rear wheel steering system used in a vehicle including a movable rail slider connected to the vehicle and a control unit that drives an electric actuator of the movable rail slider according to the vehicle speed. 2. A front steering for steering front wheels supported on a chassis side, a rear power steering for steering rear wheels supported on the chassis, and a front steering and a rear power steering thereof. Relatedly, between the front and rear wheels, a control beam that is swingably supported in the front-rear direction on the chassis side and a loop end that connects one end to each other are formed and supported by the control beam. , And a pair of control cables connecting the other end to the control valve of the rear power steering, an equalizer that is pressed by a spring against the loop end of the control cable, and in front of the control beam as appropriate. Is supported at the chassis side so that it can swing back and forth. Then, the phase switching beam oscillated by the front steering, the phase switching rack supported by the phase switching beam so as to reciprocate in the beam length direction, and the phase switching rack as the phase switching beam. An electric actuator that reciprocates, a fixed rail that extends in the front-rear direction and is fixedly arranged on the chassis side at least in the swing range of the control beam, and a fixed rail that is slidably fitted to the fixed rail. Fixed rail that is rotatably connected to the control beam
A slider, a movable rail extending in a direction orthogonal to the fixed rail and fixedly supported by the fixed rail / slider, slidably fitted to the movable rail, and rotatable on the phase switching rack. A front / rear wheel steering system used in a vehicle including a movable rail slider connected to the vehicle and a control unit that drives an electric actuator of the movable rail slider according to the vehicle speed. 3. A front steering for steering front wheels supported on the chassis side, and a rear wheel supported on the chassis side having a control valve for centering a spool by either a spring or a fluid pressure. And a rear power steering that is associated with the front steering and the rear power steering, and a control beam that is swingably supported in the front-rear direction on the chassis side between the front wheels and the rear wheels. A safety cable that breaks above a certain tensile load is formed at the loop end that connects one end to each other to support it on the control beam, and the other end at the rear end.
A pair of control cables that connect to the power steering control valve, an equalizer that is spring-loaded against the loop end of the control cable, and an appropriate distance in front of the control beam on its chassis side. A phase-switching beam that is swingably supported in the front-rear direction and that is swung by its front steering, a phase-switching rack that is supported by the phase-switching beam so that it can reciprocate in the beam length direction, and its phase. An electric actuator that reciprocates the switching rack with respect to the phase switching beam, a fixed rail that is fixedly disposed by extending in the front-rear direction on the chassis side at least in the swing range of the control beam, and a sliding rail that slides on the fixed rail. Movable fit and control Fixed rail which is rotatably connected to the beam
A slider, a movable rail that extends in a direction orthogonal to the fixed rail, and is fixedly supported by the fixed rail / slider, and slidably fitted to the movable rail so that the phase-change rack can rotate. A front / rear wheel steering system used in a vehicle including a movable rail slider connected to the vehicle and a control unit that drives an electric actuator of the movable rail slider according to the vehicle speed.