JPS6328769A - Four-wheel steering system used for vehicle - Google Patents

Abstract

PURPOSE:To improve steering properties and safety, by a method wherein, in relation to steering of a front power steering, a power steering is adapted to be steered in an iso-phrased and a reversed-phrased manner. CONSTITUTION:A 4-wheel steering system 10 is oscillatorily coupled to both ends of a front axle, and is formed with a front power steering 11, adapted to steer a pair of front axles 82 and 83 to which front wheels 100 and 101 are rotatably supported, and a rear power steering 12, adapted to a pair of rear wheel axles 91 and 92 to which rear wheels 102 and 103 are rotatably supported. An opposing type steering phase cylinder 13 is adapted to control a rear control valve 43 of a rear power steering 12, and is coupled to a link mechanism 39 of the front power steering 11. The steering phase cylinder 12 is connected to direction control valves 20-25, and is further connected to an interlocking control valve 26.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a four-wheel steering system used in a vehicle.

BACKGROUND ART In recent years, four-wheel steering, in which front wheels and rear wheels are steered, has been used in automobiles, and there is a trend to improve steering performance and driving safety.

The four-wheel steering is usually performed by front power steering and rear power steering, and in particular, the rear power steering is performed by the front power steering.
It is steered in conjunction with the power steering.

Since the rear wheels were steered using the same power steering as the front wheels, the steering system was expensive and required a large oil pump.

Objectives and Problems of the Invention The objects and problems of this invention are to avoid an increase in the capacity of the oil pump, to make the front power steering system steer the front wheels, and to make the rear power steering system steer the rear wheels. The front wheels and the rear wheels can be steered in the same phase and in opposite phases, and the front wheels and the rear wheels can be steered independently of each other so that only the front wheels can be steered, thereby improving steering performance and driving safety. Our goal is to provide four-wheel steering systems for use in vehicles.

Summary of the structural invention related to the object and problem: Contents of the claimed invention In relation to the above-mentioned object and problem, the four-wheel steering system used in the vehicle of this invention has a supply side hydraulic piping and a return side hydraulic piping. connects the front booster, oil pump, front control valve, and oil reservoir to the hydraulic circuit, and connects the front booster, oil pump, front control valve, and oil reservoir to the hydraulic circuit, and connects the front wheels to both ends of the front axle to rotatably support the front wheels. From the front power steering that steers the axle and the rear booster and the rear control valve that is located in the return hydraulic line of the front power steering and allows the rear booster to be connected to the front booster. There is a rear power steering system that steers a pair of rear wheel axles that are swingably connected to both ends of the rear axle and rotatably support the rear wheels, and a single-rod type compound on the input side that is connected oppositely to each other. It consists of a dynamic cylinder and a single-rod double-acting cylinder on the output side, which is fixedly arranged on the chassis between the front axle and the rear axle, and whose input is connected to the front power steering linkage on the front axle side. Connect the input side piston and rod of the side double acting cylinder,
and an opposed steering phase cylinder that connects the output side piston rod of the output side double acting cylinder to the rear control valve of the rear power steering;
An independent cylinder piping that connects the head side and rod side cylinder chambers of the input double acting cylinder to each other, an independent cylinder piping that connects the head side and rod side cylinder chambers of the output double acting cylinder, and the input side and Cylinder in-phase piping that connects the head-side cylinder chambers of the output-side double-acting cylinders to each other, cylinder in-phase piping that connects the rod-side cylinder chambers of the input and output-side double-acting cylinders, and the input-side double-acting cylinder. cylinder reverse phase piping that connects the rod side cylinder chamber of the output side double acting cylinder to the head side cylinder chamber of the output side double acting cylinder, and the head side cylinder chamber of the output side double acting cylinder to the rod side cylinder chamber of the input side double acting cylinder. On the upstream side of the connecting cylinder reverse phase piping, the directional control valves arranged in those piping, and the rear control valve of the rear power steering,
an interlocking control valve disposed in the return hydraulic piping of the front power steering, and a rear booster bypass connecting the return hydraulic piping to the oil reservoir side on the upstream side of the interlocking control valve; The structure includes a bypass valve disposed in the rear booster bypass, and the opposed steering phase cylinder is hydraulically independent from the front and rear power steering, and the cylinder independent piping and the cylinder same phase Selectively opens and closes the directional control valves arranged in the piping and the cylinder reverse phase piping, and switches and connects the head side and rod side cylinder chambers of the input side and output side double acting cylinder of the opposed type steering phase cylinder. and steers its front wheels and rear wheels, and in particular, in connection with steering its front power steering, its rear power steering.
The steering is in the same phase and in opposite phases, and the front wheels and rear wheels are independently steered, allowing only the front wheels to be steered.

Description of Specific Examples Preferred specific examples of the four-wheel steering system used in a vehicle according to the present invention will be described below with reference to the drawings.

1 to 6 show a specific example 10 of a four-wheel steering system used in a vehicle according to the present invention, which is applied to a truck 80. FIG.

The four-wheel steering system 10 is a front power steering system that is swingably connected to both ends of a front axle (not shown) and that steers a pair of front wheel axles 82 and 83 that rotatably support front wheels 100 and 101. - Steering 11 and rear axle (not shown)
The rear power steering 12 steers a pair of rear wheel axles 91 and 92 that are swingably connected to both ends of the rear wheels 102 and 103 and rotatably support the rear wheels 102 and 103;
2. The rear control valve 4 of the rear power steering 12 is connected to the linkage 39 of the front power steering 11 on the 83 side.
3 and a separate cylinder piping 14.15 for the steering phase cylinder 13.
, cylinder in-phase piping 16 , 17 for its steering phase cylinder 13 , cylinder anti-phase piping 18 , 19 for its steering phase cylinder 13 , and their piping 14 ,
15,16°1? , 18.19, respectively arranged directional control valves 20.21.22.23.24.25 and their associated control valves 2 for the rear power steering 12.
6, rear booster bypass 27, bypass valve 2
8.

The front power steering 11 includes a front booster 30, an oil pump 31°, a front control valve 32, an oil reservoir 33, a steering wheel 35, a steering shaft 36,
It is configured to include a pitman arm 37, a front drag link 38, and a front knuckle arm 39.

This front power steering 11 includes a front booster 30, an oil pump 31, a front control valve 32, and an oil reservoir 3.
3 is connected to a hydraulic circuit through a supply side hydraulic pipe 40 and a return side hydraulic pipe 41.

The front booster 30 is configured as an integral type including a front control valve 32 and a steering gear box 34 that enables manual steering, and is placed in front of the chassis 81 of the truck 80. Knuckles 84 on both ends of the front axle.
The pitman arm 37 and the front drag are connected to a pair of front wheel axles 82 and 83 which are pivotally connected via king pins 86 and 85 and king pins 86 and 87, and rotatably support the front wheels 100 and 101, respectively.・Link 38
, and are connected via a front knuckle arm 39. Of course, the front wheel axle 82.83 is
Rod 88 and pair of tie rod arms 89.9
They are connected to each other by 0.

Further, the front control valve 32 is gear-coupled to the steering shaft 36, and the steering control valve 32 is connected to the steering shaft 36 via the steering shaft 36.
It is operated by a wheel 35.

The rear power steering 12 is connected to the rear booster 42 and the front power steering 1
1, and is arranged in the return side hydraulic piping 41 of
It consists of a rear control valve 43 that allows the rear booster 42 to be connected to the booster 30.

The rear booster 42 is the rear control
A cylinder bore that incorporates the valve body 46 of the valve 43 and communicates with a pair of oil ports (not shown) that are switched and connected to three cylinder ports (not shown) of the rear control valve 43. (not shown)
a cylinder body 44 having a cylinder body 44, and a pair of cylinder chambers (not shown) fitted in the cylinder bore so as to be reciprocally slidable and correspondingly connected to the oil ports thereof.
A piston (not shown) is formed in the cylinder bore, and a piston rod 45 has one end fixed to the piston and extends outside the cylinder body 44 so that the other end can be taken in and out. consists of its chassis 81
Attach the cylinder body 44 to the rear knuckle arm 48, and the piston rod 45 to the rear knuckle arm 48, respectively.
Jointed. Of course, that rear knuckle
The arm 48 is swingably connected to both ends of a rear shaft disposed behind the chassis 81 of the trunk 80 via knuckles 93 and king pins 95 and 96, and rotates the rear wheels 102 and 103, respectively. is fixed to one of a pair of rear wheel axles 91, 92 that can be supported;
The rear wheel axle 91.92 is also connected to a tie rod 97 and a pair of tie rod arms 98.92 as usual.
99 and are connected to each other.

In the rear booster 42 configured in this way, the movement of the piston becomes the movement of the cylinder body 44 and piston rod 45, and is transmitted to the rear wheels 102, 103 via the rear knuckle arm 48. The rear booster 42 then steers the wheels 102, 103.

The rear control valve 43 is made into a spool valve and assembled to the cylinder body 44 of the rear booster 42, and the front power
The valves are switched in the opposite type steering phase cylinder 13 that transmits the steering of the steering wheel 11, and the front
It directs the pressure oil from the booster 30, supplies the pressure oil to the rear booster 42, and returns the pressure oil from the rear booster 42 to the oil reservoir 33.

The rear control valve 43 is arranged to be able to reciprocate and slide in a valve body 46 assembled to the cylinder body 44 of the rear booster 42 and in a spool bore (not shown) of the valve body 46. a pump port (not shown) and a tank port (not shown) formed in the valve body. ), which is similarly connected to the three cylinder ports formed in the valve body 46, fails to switch off the pressure oil flowing into the pair of cylinder chambers of the rear booster 42, and the switching operation Accordingly, the direction of the pressure oil returned from the cylinder chamber to the oil reservoir 33 is controlled.

The spool is threaded through a hole (not shown) in the valve body 46 and connected to the tip of a spool shaft 47 that extends into the spool bore. Of course,
The spool shaft 47 is ball-jointed to the output piston rod 65 of the opposed steering phase cylinder 13 so that the spool is connected to the opposed steering phase cylinder 13 for transmitting steering of the front power steering 11. The steering phase cylinder 13 slides back and forth within its spool bore.

As can be seen from FIGS. 3.5 and 6, the opposed steering phase cylinder 13 has an input cylinder body 51 and an output cylinder body 52 integrated by sharing a head cover 53 with each other. , the input side single rod type double acting cylinder 49 and the output side single rod type double acting cylinder 50 are connected oppositely to each other. Of course, the integrated input and output double-acting cylinders 49,50 are connected to the chassis 81 by Bordeaux napft means (
(not shown).

The input side single rod type double acting cylinder 49 is a cylinder.
An input side cylinder body 51 having a bore 56, fitted into the cylinder bore 56 so as to be slidable back and forth,
an input-side piston 62 defining head-side and rod-side cylinder chambers 58,59 in its cylinder bore 56;
One end is fixed to the input side piston 62, and the rod
The input side piston rod 64 extends through a hole 66 in the cover 54 so that its other end can be inserted into and taken out from the outside of the input side cylinder body 51. Head and rod side oil ports 68 and 69 are formed in the head and rod side cylinder chambers 58 and 59, respectively.

The output side single rod type double acting cylinder 5o is manufactured in the same shape as the input side single rod type double acting cylinder 49, and includes an output side cylinder body 52 having a cylinder bore 57, and a cylinder bore 57. 57 so as to be reciprocatingly slidable and forming head side and rod side cylinder chambers 60,61 in the cylinder bore 57; - Consists of an output side piston rod 65 extending through a hole 67 in the cover 55 so that its other end can be inserted into and taken out from the outside of the output side cylinder body 52, and the output side cylinder body 52 The head side and rod side oil ports 70.71 are opened in the head side and rod side cylinder chambers 60.61.
is formed.

The opposed steering phase cylinder 13 so configured
The front knuckle arm 39 is connected to the input side piston rod 64 by a ball joint, and the output side piston rod 65 is fixedly connected to the spool shaft 47. In response to the steering of the power steering 11, the rear control valve 4 of the rear power steering 12 is
3 can be operated to switch the valves in the same phase and in opposite phases, and the valve switching operation of the rear control valve 43 can be performed without transmitting the steering of the front power steering 11 to the rear control valve 43. Make it stoppable. In particular, in the opposed steering phase cylinder 13, with respect to the connection between the front knuckle arm 39 and the input piston rod 64, the input piston rod 64 is moved by the front knuckle arm 39. The displacement of the spool
At a position equal to the displacement of shaft 47 and such that the maximum displacement of input piston rod 64 is the maximum displacement of front trunk link 38, It is rotatably connected to the front knuckle arm 39.

One side of the cylinder independent piping 14.15 is connected to the input side port of the opposed steering phase cylinder 13, the head side and rod side oil port 6 of the double acting cylinder 49.
8.69 to communicate the head side and rod side cylinder chambers 58.59 with each other, and the other side of the cylinder independent piping 14.15 is connected to the output side single rod of the opposed steering phase cylinder 13. Head side and rod side oil boats in type double acting cylinder 5o 70°71
The head side and rod side cylinder chambers 60, 61 are connected to each other.

One of the cylinder in-phase pipes 16, 17 is connected between the head side oil port (68, 70) of the input side and output side single rod type double acting cylinder 49, 50 of the opposed steering phase cylinder 13, The head side cylinder chambers 58, 60 are connected to each other, and the other side of the cylinder in-phase piping 16, 17 is connected to the input side and output side single rod type double acting cylinder 4 of the opposed steering phase cylinder 13.
It is connected between the rod side oil ports 69 and 71 at 9.50 to communicate the rod side cylinder chambers 59 and 61 with each other.

One of the cylinder anti-phase piping 18 , 19 connects the head side oil port 68 of the input side single rod type double acting cylinder 49 and the output side of the output side single rod type double acting cylinder 50 in the opposed steering phase cylinder 13 . The rod side oil port 71 is connected to the head side cylinder chamber 5.
8 and the rod side cylinder chamber 61 is connected to the rod side cylinder chamber 61, and the other side of the cylinder reverse phase piping 18. The port 69 is connected to the head side oil port 70 of the output side single rod double acting cylinder 50, and the rod side cylinder chamber 59 is connected to the head side oil port 70 of the output side single rod type double acting cylinder 50.
The head side cylinder chamber 60 is connected to the head side cylinder chamber 60.

The directional control valves 20.21, 22, 23, 24°25 are electromagnetic two-way control valves, and their piping 14.15.1
6.1? , 18.19. Of course, those directional control valves 20゜21.22.23.24.2
5 is a switch box (not shown) located near the driver's seat, and solenoid coils 72, 73, 74.
75, 76 and 77 are electrically connected and opened and closed by operating a switch in the switch box.

The interlock control valve 26 is an electromagnetic two-way control valve, and is a rear control valve for the rear power steering 12.
On the upstream side of the valve 43, its front power
arranged in the return hydraulic line 41 of the steering wheel 11, in connection with its front wheels 100.101 by means of its front power steering 11, when steering its rear wheels 102.103 with its rear power steering 12; It is opened to allow pressure oil to be supplied from the front booster 30 to the rear booster 42. Of course, this interlocking control valve 26 electrically connects the solenoid coil 78 to the switch box for the directional control valves 20, 21, 22, 23, 24, 25, and operates the switch in the switch box. It is opened and closed.

The rear booster bypass 27 connects the return hydraulic line 41 to the oil reservoir 33 upstream of the motion control valve 26 and is connected to the oil reservoir 33 when the rear power steering 12 is not driven, i.e. after When the wheels 102, 103 are not steered, pressurized oil is returned from its front booster 30 to its oil reservoir 33.

The bypass valve 28 is an electromagnetic two-way control valve, which is arranged in the rear booster bypass 27, and when the rear power steering 12 is not driven, in other words, the motion control valve 26 is When closed, it is open and returns pressure oil from the front booster 30 to the oil reservoir 33 via the rear booster bypass 27 and when the rear power steering 12 is being driven. That is, when the interlocking control valve 26 is open, it is closed and the rear
Pressurized oil is stopped from returning from the front booster 30 to the oil reservoir 33 via the booster bypass 27. Of course, this bypass valve 28 is similar to that of the directional control valve 2.
Switch for 0.21.22°23.24.25
Electrically connect the solenoid coil 79 to the box,
It is opened and closed by operating a switch in the switch box.

Next, the operation of the four-wheel steering system 1° configured as described above will be described in relation to the running state of the truck 80.

First, referring to FIGS. 2 and 3, we will discuss the case where the truck 80 is driven at a low speed, for example, 30 km/h or less. , in the switch 5 box, operate the switch,
6.77 to open its directional control valve 24.25, and its solenoid' coil 72, 73, 74
．． 75, the current is turned off and the directional control valves 20, 21 .
Close 22°23.

As such, when the directional control valves 24, 25 are opened and the directional control valves 20, 21, 22, 23 are closed, the head side oil port 68 and the rod side oil port 71 are connected to each other. The head side cylinder chamber 58 of the input side double acting cylinder 49 and the rod side cylinder chamber 61 of the output side double acting cylinder 50 are connected to each other by the connected cylinder reverse phase piping 18, and the rod side oil port 69 and its head side oil port 70, the rod side cylinder chamber 59 of the input side double acting cylinder 49 and the head side cylinder chamber 60 of the output side double acting cylinder 50 are connected to each other. oil flows freely between the head cylinder chamber 58 of the input double-acting cylinder 49 and the rod-side cylinder chamber 61 of the output double-acting cylinder 50; It also flows freely between the rod-side cylinder chamber 59 of the cylinder and the head-side cylinder chamber 60 of the output-side double-acting cylinder 50, and the movement of the output-side piston 63 is opposite to that of the input-side piston 62. , so that in its opposed steering phase cylinder 13 the operation is set to antiphase.

In addition, when the opposed steering phase cylinder 13 is set to reverse phase operation, the switch is operated in the switch box to flow Tl'1M to the solenoid coil 78, and the interlock control is performed. opening valve 26 and de-energizing the solenoid coil 79 and closing the bypass valve 28 to supply pressure oil from the front booster 30 to the rear booster 42;
The rear power steering 12 is placed in a drivable state.

That is, the front wheel 1 is rotatably supported on its front wheel axle 82.83 and is steered by the front power steering 11 via the front wheel axle 82.83.
00.101 phase is that opposed steering phase cylinder 1
3, but is changed to the opposite phase by its input side single rod type double acting cylinder 49 and its output side single rod type double acting cylinder 50 in its opposed steering phase cylinder 13, and its rear control valve 43 is valved in antiphase by its opposed steering phase cylinder 13, so that its rear booster 42 is driven in antiphase with respect to its front booster 30 and is then rotatable onto the wheel axle 91,92. rear wheel 1 supported by
The actual steering angle of 02.103 is set to be synchronized in opposite phase to that of its front wheel 100.101.

Therefore, when the truck 80 is driven at low speed,
If the front wheels 100.101 are steered by the front power steering 11, then the wheels 102.103 are steered by the rear power steering 12, which is subjected to the valve switching action of the opposed steering phase cylinder 13. , and are steered in synchronization with the opposite phase.

4 and 5, the trunk 80
When the truck 80 is driven at a high speed, for example, 30 km/h or more, the solenoid coil 74 is activated by operating a switch in the switch box. .7
5 to open its directional control valve 22, 23, and its solenoid coil? At 2.73, 74.75, the current is cut off and the directional control valves 20, 21, 24°2
Close 5.

Thus, when the directional control valve 22, 23 is opened and the directional control valve 20, 21, 24, 25 is closed, the cylinder connected between the head side oil port 68, 70 The head-side cylinder chamber 58 of the input-side double-acting cylinder 49 and the head-side cylinder chamber 60 of the output-side double-acting cylinder 50 are connected to each other by the phase piping 16, and between the rod-side oil ports 69 and 71. The rod-side cylinder chamber 59 of the input-end double-acting cylinder 49 and the rod-side cylinder chamber 61 of the output-side double-acting cylinder 50 are connected to each other through the connected cylinder in-phase piping 17, and the oil is supplied to the input-side double-acting cylinder 59. It flows freely between the head-side cylinder chamber 58 of the cylinder 49 and the head-side cylinder chamber 60 of its output-side double-acting cylinder 50, and also between the rod-side cylinder chamber 59 of its input-side double-acting cylinder 49 and its output-side double-acting cylinder chamber 58. The moving cylinder 500 also flows freely between the rod side cylinder chamber 61 and the movement of its output side piston 63 is the same with respect to that of its input side piston 62, so that its opposed steering phase cylinder At 13, the operations are set to be in phase.

In addition, when the opposed steering phase cylinders 13 are set to the same phase operation, a switch is operated in the switch box to apply current to the solenoid coil 78, and the interlocking control valve 26 is activated. and the solenoid coil 79 is de-energized, the bypass valve 28 is closed, and pressure oil is supplied from the front booster 30 to the rear booster 42 and the rear power steering 12 Place it in a driveable state (.

That is, the front wheel 1 is rotatably supported on its front wheel axle 82.83 and is steered by the front power steering 11 via the front wheel axle 82.83.
00.101 phase is that opposed steering phase cylinder 1
3 is maintained in phase by its input double-acting cylinder 49 and its output double-acting cylinder 50 in its opposed steering phase cylinder 13, and its rear control valve 43 is transmitted to its opposed steering phase cylinder 13. phase cylinder 1
3, the rear booster 42 is operated in the same phase as the front booster 30.
The actual steering angles of the rear wheels 102 and 103, which are driven in the same phase with respect to each other and then rotatably supported on the wheel axles 91.92, are set to be synchronized with that of the front wheels 100 and 101 in the same phase. Ru.

Therefore, when the trunk 80 is driven at high speed,
If the front wheels 100.101 are steered by the front power steering 11, then the wheels 102.103 are steered by the rear power steering 12, which is subjected to the valve switching action of the opposed steering phase cylinder 13. The steering is performed in synchronization with the same phase.

Next, referring to FIGS. 1 and 6, we will discuss the case where the truck 80 runs by steering only the front wheels 101 and 102. In this case, the switch in the switch box is operated and the Solenoid coil 7
2.73 to open its directional control valve 20.21 and its solenoid coils 74, 75, 76.
The current is cut off to 77, and its directional control valves 22, 23, 24
．． Close 25.

As such, when the directional control valve 20.21 is opened and the directional control valve 22.23, 24.25 is closed, the head side and rond side oil ports 68
．． The head side and rod side cylinder chambers 58,59 of the input side double acting cylinder 49 are connected to each other by the cylinder independent piping 14 connected between the cylinder 79, and the head side and rod side oil ports 70,71 are connected to each other. The head side and rod side cylinder chambers 60° 61 of the output side double acting cylinder 50 are connected to each other by the connected cylinder independent piping 15, and oil is supplied to the head side and rod side cylinder chambers in the input side double acting cylinder 49. 58, 59, and in the double-acting cylinder 50 on its output side, it also flows freely between the head side and rod side cylinder chambers 60, 61, and the input side and output side pistons 62.
63 is freely slid back and forth within the corresponding cylinder bore 56.57, in other words its input and output double acting cylinders 49.50 are set in free motion.

Also, once the opposed steering phase cylinder 13 is set, a switch is operated in the switch box to energize the solenoid coil 79 to open the bypass valve 28, and , the solenoid coil 78 is de-energized, the interlock control valve 26 is closed, and pressure oil is supplied to the front booster 30.
to its oil reservoir 33 and put its rear power steering 12 into lost motion.
put in a state.

Therefore, the front wheels 100, 101 are connected to the front wheel axle 82.
．． Its front power steering via 83 1
1, the steering of the front power steering 11 is transmitted to the opposed steering phase cylinder 13, where the input and output double-acting cylinders 49 Since the .50 is in free motion, its rear control
The valve 43 is no longer valve-switched by its opposed steering phase cylinder 13, its rear booster 42 undergoes a lost motion, and eventually only its front wheels 100, 101 are steered, and in this case:
The wheels 102, 103 are then placed in a self-steering condition.

Also, if the trunk 80 is provided with steering lock means including an air chamber, in case only its front wheels 100, 101 are steered, then the wheels 102, 103 are steered. can be placed in any condition.

Conveniences and Benefits of the Invention From the above, compared to the four-wheel steering systems used in vehicles that have already been proposed and used, the four-wheel steering system used in the vehicles of this invention is Piping and return hydraulic piping connect the front booster, oil pump, front control valve, and oil reservoir to the hydraulic circuit and are swingably connected to both ends of the front axle, allowing the front wheels to rotate. Front power steering steers a pair of supported front wheel axles, and rear
It consists of a booster and a rear control valve that is arranged in the return side hydraulic line of the front power steering to connect the rear booster to the front booster, and is swingably connected to both ends of the rear axle. , a rear power steering system that steers a pair of rear wheel axles that rotatably support the rear wheels, and a single-rod double-acting cylinder on the input side and a single-rod double-acting cylinder on the output side that are connected oppositely to each other. is fixedly disposed on the chassis between the front axle and the rear axle, and connects the input piston rod of the input double-acting cylinder to the front power steering linkage on the front axle side. , and an opposed steering phase cylinder that connects the output piston rod of the output double-acting cylinder to the rear control valve of the rear power steering, and the head side and rod side of the input double-acting cylinder. Cylinder independent piping that connects the cylinder chambers to each other, cylinder independent piping that connects the head side and rod side cylinder chambers of the output side double acting cylinder to each other, and the head side cylinder chambers of the input side and output side double acting cylinders to each other. Cylinder in-phase piping to be connected, and cylinder in-phase piping to connect the input end and the rod-side cylinder chamber of the output-side double-acting cylinder to each other;
Cylinder reverse phase piping that connects the rod side cylinder chamber of the output side double acting cylinder to the head side cylinder chamber of the input side double acting cylinder, and the output side double acting cylinder to the rod side cylinder chamber of the input side double acting cylinder. The cylinder reverse phase piping that connects the head side cylinder chamber of the
Upstream of the steering rear control valve, there is an interlock control valve disposed in the return hydraulic line of the front power steering; and upstream of the interlock control valve, the return hydraulic line is connected to the oil The four-wheel steering system used in the vehicle of this invention is configured to include a rear booster bypass connected to the reservoir side and a bypass valve disposed in the rear booster bypass. The steering phase cylinder is hydraulically independent from the front and rear power steering, and its directional control valves are selectively opened and closed, and its opposite side is controlled by cylinder independent piping, cylinder in-phase piping, and cylinder anti-phase piping. The head side and rod side cylinder chambers of the input side and output side double acting cylinders in the type steering phase cylinder are switched and connected, and the output side double acting cylinder is operated in the same phase and opposite phase to the input side double acting cylinder, Also, its input and output double-acting cylinders are freely extended and retracted, its opposed steering phase cylinders are set for in-phase operation, anti-phase operation, and free motion, and its front wheels are controlled by its front power.・It is steered by the steering wheel, and at the same time its rear control valve is controlled by its front control valve.
In conjunction with power steering steering, the opposed steering phase cylinders are engaged in in-phase and out-of-phase pulp switching operations, and are no longer engaged in pulp switching operations, with the result that the wheels are subsequently driven by the rear power steering. , its front wheels can be steered in-phase and out-of-phase, and it is also possible to steer only its front wheels, thus improving steering performance and running stability, and furthermore, the wheels can then be steered. Oil for steering
This eliminates the need for a pump, suppressing the increase in the so-called oil pump capacity, thereby suppressing an increase in the power consumption of the engine installed in the vehicle, and furthermore, the opposed steering phase cylinder is extremely small. As a result, ordinary power steering can be used, manufacturing is extremely easy and inexpensive, and it is useful for four-wheel steering of vehicles.

As for the relationship between the invention and the specific examples, from the specific examples of the present invention described with reference to the drawings, various design modifications will be apparent to those who have ordinary knowledge in the technical field to which this invention pertains. Furthermore, the contents of this invention are essential to the establishment of the invention for accomplishing the task of the invention, and are derived from the technical characteristics of the invention that are the nature of the invention. and can be easily replaced with a form that is objectively recognized as incorporating it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a four-wheel steering system used in a vehicle of the present invention, which is applied to a truck and is in a state where only the front wheels are being steered. FIG. 3 is a schematic diagram of the four-wheel steering system shown in FIG. A schematic diagram of the four-wheel steering system shown in FIG. 5 is a hydraulic circuit diagram of the opposed steering phase cylinder in the four-wheel steering system shown in FIG.
and FIG. 6 is a hydraulic circuit diagram of the opposed steering phase cylinders in the four-wheel steering system shown in FIG. 11...Front power steering, 12...
・Rear power steering, 13...Opposed steering phase cylinder, 14.15...Cylinder independent piping, 1
6.17... Cylinder same phase piping, 18.19...
Cylinder reverse phase piping, 20, 21, 22, 23° 24.
25... Direction control valve, 26... Interlocking control valve, 27.
...Rear booster bypass, 28...Bypass valve, 49...Input side single rod type double acting cylinder, 50...
・Output side single-mouth 7-stroke double-acting cylinder. Figure 1 Figure 6 Figure 2 Figure 13 Figure 4 Figure jI5

Claims (1)

[Scope of Claims] A front booster, an oil pump, a front control valve, and an oil reservoir are connected to a hydraulic circuit by supply-side hydraulic piping and return-side hydraulic piping, and are swingable to both ends of the front axle. A front power steering system that steers a pair of front wheel axles that are connected to each other and rotatably support the front wheels, a rear booster, and a rear booster that is arranged in the return side hydraulic piping of the front power steering and connected to the front booster. Rear power steering consists of a rear control valve that enables the rear booster to be connected, is swingably connected to both ends of the rear axle, and steers a pair of rear wheel axles that rotatably support the rear wheels. It consists of an input-side single-rod type double-acting cylinder and an output-side single-rod type double-acting cylinder connected oppositely to each other, and is fixedly arranged on the chassis between the front axle and the rear axle, and the front wheel The input side piston rod of the input side double-acting cylinder is connected to the link mechanism of the front power steering on the shaft side, and the rear power steering
An opposed steering phase cylinder that connects the output piston rod of its output double-acting cylinder to the steering rear control valve, and an independent cylinder that connects the head-side and rod-side cylinder chambers of the input double-acting cylinder to each other. piping; cylinder independent piping that connects the head side and rod side cylinder chambers of the output side double acting cylinder to each other; and cylinder in-phase piping that connects the head side cylinder chambers of the input side and output side double acting cylinder to each other; Cylinder in-phase piping that connects the rod-side cylinder chambers of the input-side and output-side double-acting cylinders to each other, and connects the rod-side cylinder chamber of the output-side double-acting cylinder to the head-side cylinder chamber of the input-side double-acting cylinder. Cylinder reverse phase piping, Cylinder reverse phase piping that connects the head side cylinder chamber of the output side double acting cylinder to the rod side cylinder chamber of the input side double acting cylinder, and the directional control valves arranged in each of those pipings. , upstream of the rear control valve of the rear power steering, an interlocking control valve disposed in the return side hydraulic piping of the front power steering, and upstream of the interlocking control valve, the return side of the interlocking control valve. Rear booster connecting hydraulic piping to its oil reservoir side.
A four-wheel steering system used in a vehicle that includes a bypass and a bypass valve located in the rear booster bypass.