JP3402702B2 - Four-wheel steering system for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front wheel steering rack pinion.
On-type hydraulic power steering mechanism and rear wheel steering rack
Vehicle equipped with a pinion hydraulic power steering mechanism
A four-wheel steering device. 2. Description of the Related Art Japanese Patent Application Laid-Open No. Hei 5-131948 discloses
Four-wheel steering system is a rack and pinion hydraulic
Power steering mechanism and rack and pinion type for rear wheel steering
And a hydraulic power steering mechanism. The front wheel
Rack and pinion hydraulic power steering mechanism for steering
Is a front wheel pinion that rotates according to the steering
Front wheel rack meshing with pinion and front wheel steering assist force
Acting on the front wheel and the front wheel
For front wheels that control hydraulic oil supplied to hydraulic actuators
And a control valve. Rear wheel steering rack and pinion
The hydraulic power steering mechanism has a rear wheel pinion,
The rear wheel rack that meshes with this rear wheel pinion and the rear wheel
A rear wheel hydraulic actuator for applying a steering assist force,
Controls the pressure oil supplied to the wheel hydraulic actuator after that
And a control valve for the rear wheel. A piston rod is provided at one end of the front wheel rack.
Auxiliary oil having a first auxiliary piston connected via a
The pressure cylinder and the rear wheel pinion rotate according to its own rotation.
Auxiliary pinion to be
An auxiliary rack and a second auxiliary pin that moves with the auxiliary rack.
And a second auxiliary hydraulic cylinder having a stone.
One of the pair of oil chambers of the first auxiliary hydraulic cylinder and the second auxiliary hydraulic cylinder
One of the pair of oil chambers of the hydraulic cylinder is connected to
The other of the pair of oil chambers of the first auxiliary hydraulic cylinder and the second auxiliary hydraulic pressure
The other of the pair of oil chambers of the cylinder is connected. [0004] The cylinder portion of the first auxiliary hydraulic cylinder
A circumferential groove is formed on the inner surface, and a first auxiliary piston is formed in the circumferential groove.
Both oils separated by the first auxiliary piston by entering
It is assumed that the rooms communicate. [0005] According to the four-wheel steering system, the front wheel pinion is provided.
The front wheel rack is moved by the rotation of the
If done, the pressure oil pressure controlled by the front wheel control valve
Is supplied to the front wheel hydraulic actuator to assist in steering the front wheels.
Help is provided. Also, accompanying the front wheel rack
The first auxiliary piston of the first auxiliary hydraulic cylinder moves
And the pressure oil corresponding to the movement amount is supplied to the second auxiliary hydraulic cylinder.
The second auxiliary piston moves and the second auxiliary piston moves.
Auxiliary pini meshes with an auxiliary rack that moves along with the ton
The on rotates and the rear wheel pinion rotates. For this rear wheel
The rear wheel rack is moved by the rotation of the pinion,
Can steer the wheels and steer the rear wheels.
The hydraulic oil pressure-controlled by the rear-wheel control valve
Is supplied to the hydraulic actuator for
Granted. If the front wheel steering amount is less than a certain value, the first
The two oil chambers separated by the auxiliary piston communicate with each other,
It is assumed that no pressure oil is supplied to the auxiliary hydraulic cylinder and the rear wheel
The steering amount is set to 0 when traveling straight ahead and when the steering angle is small.
Running stability when cornering at high speeds
You. [0006] In the above conventional structure,
1 Connect the piston rod of the auxiliary hydraulic cylinder
Because it is connected to one end, the size of the first auxiliary hydraulic cylinder increases.
You. The piston rod of the first auxiliary piston is
It is necessary to protrude to the outside of the
Must be covered with a telescopic cover that covers the front wheel rack.
Therefore, a large telescopic cover is newly required. Also, the first
Enters the circumferential groove on the inner surface of the cylinder part of the auxiliary hydraulic cylinder
When the first auxiliary piston moves, the first auxiliary piston
Seal ring on the outer circumference of the groove is caught on the edge of the circumferential groove and is damaged
Therefore, it cannot be put to practical use. The present invention can solve the above problems.
It is an object of the present invention to provide a four-wheel steering system for a vehicle. [0008] Four-wheel steering of a vehicle according to the present invention.
The device is a rack and pinion hydraulic power steering for front wheel steering.
Ring mechanism and rear wheel steering rack and pinion hydraulic power
A rack and pinion for steering the front wheels.
The hydraulic hydraulic power steering mechanism rotates according to the steering.
Before engaging with the front wheel pinion
Wheel rack and front wheel hydraulic pressure that generates front wheel steering assist force
Actuator and this front wheel hydraulic actuator
And a front wheel control valve for controlling the hydraulic pressure used.
Rack-pinion type hydraulic power steering machine for rear wheel steering
The structure is meshed with the rear wheel pinion and this pinion
Rear wheel rack and rear wheel for generating rear wheel steering assist force
Hydraulic actuator and this rear wheel hydraulic actuator
A rear wheel control valve for controlling the hydraulic pressure acting on the
A first auxiliary pinion that rotates in accordance with the rotation of the front wheel pinion;
ON and the first auxiliary rack engaged with the first auxiliary pinion.
And the first auxiliary rack that moves in accordance with the movement of the first auxiliary rack.
A first auxiliary hydraulic cylinder having an auxiliary piston;
A second auxiliary pinion that rotates the rear wheel pinion according to rolling
And a second auxiliary rack engaged with the second auxiliary pinion
And move the second auxiliary rack according to its own movement.
A second auxiliary hydraulic cylinder having a second auxiliary piston is provided.
And a pair of first auxiliary pistons
A pair of oil chambers and a second auxiliary piston
Connected to one of the oil chambers and its first auxiliary piston
By the other of the pair of oil chambers to be partitioned and the second auxiliary piston
It is characterized by being connected to the other of a pair of oil chambers to be partitioned
And The front wheel pinion and the first auxiliary pinion
Are coaxial and rotate together with the first auxiliary pin.
The amount of movement of the first auxiliary rack per unit rotation of the Nion is
Movement of front wheel rack per unit rotation of wheel pinion
Preferably, it is smaller than that. [0010] The one partitioned by the first auxiliary piston
Move the first auxiliary rack through the oil passage communicating with the pair of oil chambers.
A moving member that opens and closes by moving according to
Oil passage is preferably opened when the amount of front wheel steering is below a certain level.
Good. According to the structure of the present invention, the rotation of the front wheel pinion is achieved.
To move the front wheel rack to steer the front wheels
And the pressure oil pressure-controlled by the front wheel control valve
Steering assist force for the front wheels
Granted. The first supplement according to the rotation of the front wheel pinion
The rotation of the auxiliary pinion moves the first auxiliary rack.
Movement of the first auxiliary piston according to movement of the first auxiliary rack
The one of the pair of oil chambers of the first auxiliary hydraulic cylinder
One of the pair of oil chambers of the second auxiliary hydraulic cylinder
Is supplied with pressure oil. By the supply of the pressure oil, the second auxiliary pin
The stone moves and responds to the movement of this second auxiliary piston.
The movement of the second auxiliary rack rotates the second auxiliary pinion
And a rear wheel pinion according to the rotation of the second auxiliary pinion.
The rear wheel rack is moved by the rotation of the
Can do it. Also, when steering the rear wheels,
The hydraulic oil pressure controlled by the control valve for
Is supplied to the actuator to provide rear-wheel steering assist
You. The first auxiliary piston is a front wheel pinion.
1st auxiliary by rotation of 1st auxiliary pinion according to rotation of 1st
Since the rack moves by moving, the piston rod
1st auxiliary hydraulic system compared to connecting the
The dimension of the cylinder in the axial direction can be shortened. In addition, the first supplement
The piston rod of the auxiliary piston projects outside the cylinder
Because it is not necessary to make
No need to cover. The front wheel pinion and the first auxiliary pinion
Are coaxial and rotate together with the first auxiliary pin.
Movement amount of 1st auxiliary rack per unit rotation of Nion is before
Movement of front wheel rack per unit rotation of wheel pinion
Is smaller than the maximum
Make the troke smaller than the maximum stroke of the front wheel rack
it can. As a result, the first auxiliary piston is
The first auxiliary hydraulic cylinder is smaller than when moving together
Can be When the front wheel steering amount is less than a predetermined value, the first auxiliary pin
An oil passage communicating with a pair of oil chambers separated by a stone is opened.
As a result, pressure oil is supplied to the second auxiliary hydraulic cylinder.
The steering amount of the rear wheel is 0, and the vehicle is traveling straight ahead and the steering angle
Of running stability when cornering at high speed
Can be The opening and closing of the oil passage is moved to the first auxiliary rack.
By using a moving member that moves according to the movement,
Such damage of the seal ring of the first auxiliary piston occurs.
Never. Embodiments of the present invention will be described below with reference to the drawings.
I do. The four-wheel steering system for a vehicle shown in FIG.
Rack and pinion hydraulic power steering mechanism F for rudder
Rack-pinion type hydraulic power steering machine for rear wheel steering
And a frame R. The rack and pinion hydraulic power for steering the front wheels
-The steering mechanism F, as shown in FIG.
The input shaft 2F connected to the handle, and the input shaft 2F
Provided on output shaft 3F connected via torsion bar 6F
Front wheel pinion 25F and front wheel pinion 2
Front wheel rack 4F having teeth meshing with 5F, in front of it
Rack rack that covers wheel pinion 25F and front wheel rack 4F
From the housing 5F and one end of the rack housing 5F
The rack housing covers the protruding front wheel rack 4F.
And a cylinder 9F connected to the cylinder 5F. That input
The shaft 2F is barely connected to the valve housing 7F and the output shaft 3F.
Are supported rotatably via the ring 8F, 12F.
The output shaft 3F is connected to a pair of bare
It is rotatably supported via rings 10F and 11F.
You. The other end of the rack housing 5F and the cylinder 9F
A ball is attached to each end of the front wheel rack 4F protruding from one end.
Joint 12F, Tie rod 13F, Knuckle arm
The front wheels are connected via the like. Thereby, the input shaft 2F
The front wheels are moved by the axial movement of the front wheel rack 4F due to the rotation.
Is steered. Each end of the front wheel rack 4F expands and contracts
Covered by the cover 14F, muddy water and dust etc.
Intrusion into the 5F and the cylinder 9F is prevented.
The front wheel rack 4F is attached to one end of the cylinder 9F.
The bush 15F is shifted in the horizontal direction in FIG.
Supported via a movable support yoke 16F,
Press the support yoke 16F against the front wheel rack 4F.
A spring 17F is provided to bend and reduce the front wheel rack 4F.
Front wheel rack 4F
And smooth engagement with the front wheel pinion 25F
You. On the outer periphery of the front wheel rack 4F, a front wheel
The front wheel piston 21F is provided with a ton 21F.
The pair of oil chambers 22F, 23F to be partitioned is a cylinder 9F.
And the ends of the oil chambers 22F and 23F are sealed.
Sealing device 18F, 19F,
Front wheel hydraulic cylinder 20F for generating front wheel steering assist force
Is configured. Supply pressure oil to each oil chamber 22F, 23F
One end of each of the pipes 26F and 27F for performing the
The other end of each of the pipes 26F and 27F is a front wheel hydraulic pressure.
Rotary type that controls hydraulic pressure acting on cylinder 20F
Is connected to the front wheel control valve 30F. The front-wheel control valve 30F is a front-wheel oil control valve.
The pressure is applied to the pressure cylinder 20F according to the direction and magnitude of the steering resistance.
It supplies oil and can rotate relative to the outer circumference of the input shaft 2F
Is provided with a cylindrical valve member 31F fitted to the valve. The valve
The member 31F is attached to the outer periphery of the output shaft 3F via a pin 32F.
They are fitted to rotate in rows. The valve housing
7F, an inlet port 34F connected to the pump 33,
An outlet port 36F connected to the tank 35 and a front wheel oil
The first cylinder connected to one oil chamber 22F of the pressure cylinder 20F
Port 37F and a second port connected to the other oil chamber 23F.
Port 38F is formed. Each port 34F, 36
F, 37F and 38F are provided between the input shaft 2F and the valve member 31F.
Constriction formed in the oil passage
But the input shaft 2F and the valve due to the torsion of the torsion bar 6F
The opening is adjusted by relative rotation with the member 31F. That is, as shown in FIG.
The first concave portion 50F along the axial direction on the inner periphery of F is equally spaced in the circumferential direction.
8 places are formed. Circumferential direction of the first recess 50F
The second concave portion 51F is formed on the outer periphery of the input shaft 2F so as to face the
Are formed at equal intervals in the circumferential direction. The first recess
50F is provided via a flow path 53F formed in the valve member 31F.
A valve communicating with the first port 37F and a valve member 31F
Communicates with the second port 38F through the flow path 54F formed in
Are alternately arranged in the circumferential direction. Its second recess
51F is provided via a flow path 55F formed in the valve member 31F.
The one that communicates with the inlet port 34F and the one below the input shaft 2F
Into the torsion bar 6F from the flow path 56F formed on the other side.
On the input shaft 2 via the flow path 57F between the inner and outer circumferences with the force shaft 2F
Communicating with the outlet port 36F from the channel 58F formed on the side
Are alternately arranged in the circumferential direction. The first recess 5
The edge along the axial direction of 0F and the axial direction of the second concave portion 51F
Apertures A, B, C, and D are defined between the edges and the circumferential direction.
FIG. 6 shows that steering is not being performed and steering resistance is not acting.
In the neutral state, between the narrow portions A, B, C, and D in the circumferential direction.
The gaps are equal to each other. In this neutral state, the entrance port
G and the outlet port 36F communicate with each other.
Oil flowing into the front wheel control valve 30F from the tank 35
It recirculates and no steering assist force is generated. Steer left or right
The torsion bar 6F
Is twisted, and the valve member 31F and the input shaft 2F relatively rotate.
And the circumferential relative positions of the first recess 50F and the second recess 51F
Position changes, and the inlet port 34F and the first port 37F
The opening of the throttle portion A between the first port 37F and the first port 37F
The opening degree of the throttle portion B between the outlet port 36F and the outlet port 36F is small.
Between the inlet port 34F and the second port 38F.
The opening of the portion C becomes smaller, and the second port 38F and the outlet port
The opening degree of the throttle portion D between the opening 36F and the opening 36F increases. to this
From the oil chamber 22F of the front wheel hydraulic cylinder 20F.
Pressure oil with a pressure corresponding to the direction and magnitude of the steering resistance is supplied.
The oil is returned to the tank 35 from the other oil chamber 23F.
If the steering assist force to one of the left and right is the front wheel piston 21F
Act on the front wheel rack 4F. Steer left or right
And the valve member 31F and the input shaft 2F are steered to one of the left and right.
Relative rotation in the direction opposite to the case, the opening degree of the throttle portion A becomes smaller.
As a result, the opening of the throttle portion B increases, and the opening of the throttle portion C increases.
And the degree of opening of the throttle portion D becomes smaller,
The steering assist force is moved from the front wheel piston 21F to the front wheel rack 4
Acts on F. Rack and pinion hydraulic power for rear wheel steering
-As shown in FIG. 5, the steering mechanism R
The rudder rack and pinion hydraulic power steering mechanism R
Rack and pinion hydraulic power steering machine for front wheel steering
Since the structure is substantially the same as the structure F, FIGS.
2 shows the components of the structures F and R, and a rack and pinion for front wheel steering.
Of components of hydraulic hydraulic power steering mechanism F
Of the rear wheel steering rack-pinion type hydraulic power
-The reference numerals of the components of the steering mechanism R are suffixed with R.
And ), The input shaft 2R and the input shaft 2R
Provided on the output shaft 3R connected via the
Rear wheel pinion 25R and rear wheel pinion 25R
Rear rack 4R having teeth that mesh with the rear wheel
Rack housing for covering pinion 25R and rear wheel rack 4R
5R and projecting from one end of the rack housing 5R.
Rack housing 5 so as to cover rear wheel rack 4R
And a cylinder 9R connected to R. Its input shaft 2
R is a bearing on the valve housing 7R and the output shaft 3R
It is rotatably supported via 8R and 12R. That
The output shaft 3R is connected to the rack housing 5R by a pair of bearings.
It is rotatably supported via the connectors 10R and 11R. So
Of the rack housing 5R and one end of the cylinder 9F
A ball joy is attached to each end of the rear wheel rack 4R projecting from
12R, tie rod 13R, knuckle arm, etc.
The front wheels are connected. This allows the input shaft 2R to rotate.
Of the rear wheels by the axial movement of the rear wheel rack 4R
Is made. Then each end of the wheel rack 4R is a telescopic cover
14R, muddy water, dust, etc.
Intrusion into the cylinder 9R is prevented. afterwards
The wheel rack 4R is attached to one end of the cylinder 9R.
Bush 15R and can be moved in the horizontal direction in FIG.
Supported by the support yoke 16R
Spring 1 that presses toy yoke 16R against rear wheel rack 4R
7R is provided, and the rear wheel rack 4R bends and rack teeth
Of rear wheel rack 4R and rear wheel
The engagement with the pinion 25R is facilitated. The rear wheel rack 4R is provided on the outer periphery of the rear wheel rack 4R.
The rear wheel piston 21R is provided with a ton 21R.
The pair of oil chambers 22R and 23R to be partitioned is a cylinder 9R.
And the ends of the oil chambers 22R, 23R are sealed.
Sealing device 18R, 19R
Rear wheel hydraulic cylinder 20R that generates rear wheel steering assist force
Is configured. Supply pressure oil to each oil chamber 22R, 23R
One end of each of the pipes 26R and 27R is provided with a cylinder 9R.
The other end of each of the pipes 26R and 27R is connected to a rear wheel hydraulic pressure.
Rotary type that controls oil pressure acting on cylinder 20R
Is connected to the rear wheel control valve 30R. The rear wheel control valve 30R has a rear wheel
When the steering wheel is steered to the right, the rear wheel hydraulic cylinder 20R
A pressure corresponding to the direction and magnitude of the steering resistance is applied to one oil chamber 22R.
The pressure oil is supplied from the pump 33 and the other oil chamber 23R is
Return oil to the tank 35 and steer to the left or right of the vehicle
Auxiliary force is applied from the rear wheel piston 21R to the rear wheel rack 4R.
When the rear wheels are steered to the other side,
The steering assist force to the other of the left and right is applied to the rear wheel piston 21R.
On the rear wheel rack 4R. This rear wheel control valve
The configuration and function of the valve 30R
5 and 6, the control valve for the front wheel is used.
The same components as those in 30F are indicated by the same reference numerals except for the end code.
The description is not repeated. As shown in FIG. 2, the front wheel pinion 2
A first auxiliary pinion 61 which rotates according to the rotation of 5F,
First auxiliary rack 62 meshing with the first auxiliary pinion 61
The first auxiliary rack 62 moves in accordance with the movement of the first auxiliary rack 62.
A first auxiliary hydraulic cylinder 64 having an auxiliary piston 63;
Is provided. The first auxiliary pinion 61 is a pinion for a front wheel.
Lock screw on male screw 65 provided integrally with ON 25F
A female screw portion 61a screwed through the socket 66,
Projects downward from lower end opening 5bF of rack housing 5F
Then, it rotates coaxially with the front wheel pinion 25F. This
The first auxiliary pinion 61 has a cylindrical portion on the rack housing 5F.
To the first auxiliary housing 68 attached via the material 67
Built-in. The cylindrical member 67 is connected to the first auxiliary housing 6.
8 into the upper opening 68a formed through a seal ring.
The external thread formed on the outer periphery of one end
Threaded portion formed on the inner periphery of lower end opening 5bF of ring 5F
And a flange 67a formed on the outer periphery of the other end.
The first auxiliary housing 68 to the rack housing 5F.
Press The flange 67a of the cylindrical member 67
Lock nut 69 is screwed into the male screw formed on the outer circumference of
The cylindrical member 67 and the lock nut 69 are the first auxiliary.
Through the lower opening 68b formed in the housing 68
And the lower opening 68b is closed via a seal ring.
The tip of the first auxiliary pinion 61 is connected to the closing member 68d
A supporting bearing 70 is mounted. Both ends of the first auxiliary housing 68 are plugs.
Has a cylinder portion 68c closed by lugs 71, 72
The first auxiliary rack 62 is axially connected to the cylinder 68c.
It is inserted movably in the direction. The first auxiliary piston 63 has a first auxiliary rack 63.
The first auxiliary piston is formed integrally with one end of
A pair of oil chambers 74 and 75 partitioned by the
Formed inside the cylinder portion 68c of the auxiliary housing 68
And the first auxiliary piston 63 and the cylinder portion 68c
The first auxiliary hydraulic cylinder 64 is configured. In addition,
1 A seal ring 76 is provided on the outer periphery of the auxiliary piston 63.
It is attached. As a result, the front wheel pinion 25F
When the first auxiliary pinion 61 rotates due to rotation, the first auxiliary
The rack 62 moves in the axial direction, and the first auxiliary rack 6
The first auxiliary piston 63 moves together with the movement of the second piston.
The first auxiliary per unit rotation of the first auxiliary pinion 61
The moving amount of the rack 62 is the unit time of the front wheel pinion 25F.
1/4 of the moving distance of front wheel rack 4F
I have. One oil of the first auxiliary hydraulic cylinder 64
As shown in FIG. 4, the pipe 121 leading to the chamber 74 is
The pair of oil chambers 74 and 75 of the auxiliary hydraulic cylinder 64 communicate with each other.
Connected to an oil passage opening / closing mechanism 122. That is,
The opening / closing mechanism 122 is formed on the first auxiliary housing 68.
Moving member 124 inserted into the formed through hole 123,
The plastic screwed into the through hole 123 via the seal member 130
Compression coil interposed between the motor 125 and the moving member 124
And a spring 126. The moving member 12 of the through hole 123
4 is inserted into the first supplement through an oil passage 127 and a pipe 121.
One oil chamber 74 of the auxiliary hydraulic cylinder 64 communicates with
The other oil chamber of the first auxiliary hydraulic cylinder 64 via the path 128
75, and the insertion portion of the spring 126 in the through hole 123
Is used to balance the hydraulic pressure acting on the moving member 124.
Therefore, it communicates with the other oil chamber 75 via the oil passage 129. The transfer
The moving member 124 has a peripheral groove 126a on the outer periphery, and the first auxiliary
It can be moved in a direction perpendicular to the axis of the
On the outer peripheral surface of the first auxiliary rack 62 by the elastic force of the screw 126
It is pressed against the formed cam surface 62a. This
The moving member 124 is moved by the movement of the first auxiliary rack 62.
It moves according to the shape of the cam surface 62a, and the steering angle of the front wheels is set.
In the case where the angle is equal to or smaller than the fixed angle, as shown in FIG.
The two oil chambers 74 and 75 of the auxiliary hydraulic cylinder 64 are
If the steering angle of the front wheels exceeds the set angle
In this case, as shown in (2) of FIG.
The moving member 124 between the oil chambers 74 and 75 of the
Will be closed. The moving member 124 is provided on the cam surface 62a.
To the position corresponding to the steering angle to move according to the shape of the steering wheel.
Positioning can be performed well. As shown in FIG. 3, a rack pini for rear wheel steering is provided.
Fits on input shaft 2R of ON-type hydraulic power steering mechanism R
Sleeve 85 joined together and connected by pins 86
One end of the second auxiliary pinion 81 is inserted into
The auxiliary pinion 81 and the sleeve 85 are
Are connected to rotate in a row so that the second auxiliary pinion
The rear wheel pinion 25R rotates in accordance with the rotation of the pin 81.
The second auxiliary rack 8 meshing with the second auxiliary pinion 81
2 is provided, and this second auxiliary rack 82 is used for its own movement.
Second auxiliary having a second auxiliary piston 83 to be moved in response
A hydraulic cylinder 84 is provided. The second auxiliary pinion 81 is used for rear wheel steering.
Rack and pinion hydraulic power steering mechanism R
Second auxiliary housing attached to the housing 7R
88. The second auxiliary housing 88 is
(2) A cylindrical connecting portion 88a along the axis of the auxiliary pinion 81
And a cylinder along the axial direction of the second auxiliary rack 82.
Part 88c, and the connecting part 88a has a valve housing.
The fitting 7R is fixedly fitted to the outer periphery of the upper end. Its connecting part 8
8a to the internal thread formed on the inner periphery of the sleeve 85
A male screw formed on the outer periphery of the fitted cylindrical member 89 is a screw.
And the inner periphery of the connecting portion 88a is
Prevention of removal of seal member 90 between outer periphery of sleeve 85
Has been made. The other end of the second auxiliary pinion 81
The bushings 98, 99 and the base are attached to the second auxiliary housing 88.
The bearing 91 is supported via an
2 To the external thread formed on the outer periphery of the other end of the auxiliary pinion 81
The nut 92 is screwed together to prevent the nut from coming off. That
A bearing 91 and a nut 92 are provided in the second auxiliary housing 88.
The upper opening formed for inserting the
It is closed by being entangled. The cylinder part of the second auxiliary housing 88
Both ends of 88c are closed by plugs 94 and 95,
The second auxiliary rack 82 is moved to the cylinder 88c in the axial direction.
It is movably inserted. The second auxiliary piston 83 has a second auxiliary
The second auxiliary piston is formed integrally with one end of
A pair of oil chambers 96 and 97 separated by the
Formed inside the cylinder portion 88c of the auxiliary housing 88
And the second auxiliary piston 83 and the cylinder portion 88c
A second auxiliary hydraulic cylinder 84 is configured. In addition,
2 A seal ring 108 is mounted on the outer periphery of the auxiliary piston 83.
Is attached. Also, the other end of the second auxiliary rack 82
A pair of spring receivers 101, 1
02 is inserted movably in the rack axis direction, and each spring
A compression coil spring 103 is disposed between
It is. When the steering angle of the rear wheel is 0 degrees, the spring 103
Each spring receiver 101, 102 is a second auxiliary housing
Rear wheel is steered left or right
Then, one spring receiver 101 is an end of the rod part 100.
Is pushed through nut 104 screwed to
When the rear wheel is steered left and right, the other
The spring receiver 102 is a flange 1 on the outer periphery of the rod portion 100.
The spring 103 is compressed by being pushed through the pin 00a. What
In addition, penetration for passing oil through each spring receiver 101, 102
Holes 101a and 102a are formed. Thereby, the second
When the auxiliary rack 82 moves in the axial direction, the second auxiliary pin
ON 81 rotates and the second auxiliary piston 83 accompanies
Moving. Per unit rotation of the second auxiliary pinion 81
The amount of movement of the second auxiliary rack 82 is limited by the front wheel pinion 25.
More than the amount of movement of the front wheel rack 4F per unit rotation of F
Has been made smaller. As shown in FIG. 1, the first auxiliary hydraulic
Oil chamber 74 of the cylinder 64 and the second auxiliary hydraulic cylinder 84
A pipe 111 for connecting one of the oil chambers 96 with the first
The other oil chamber 75 of the auxiliary hydraulic cylinder 64 and the second auxiliary hydraulic pressure
Piping 112 connecting the other oil chamber 97 of the cylinder 84
Are provided. Oil in one of the pipes 111
When the pressure exceeds the set value, one pipe 111
A first pilot check allowing oil flow to the pipe 112
The hydraulic pressure in the valve 113 and the other pipe 112 is set.
When the value exceeds a predetermined value, the other pipe 112 to one pipe 11
2nd pilot check valve 1 that allows oil flow to 1
14 are provided. According to the above arrangement, the front handle is operated by operating the handle.
The front wheel rack 4F is moved by the rotation of the wheel pinion 25F.
The front wheel control valve 30
The pressure oil pressure-controlled by F is applied to the front wheel hydraulic cylinder 20.
F is supplied to the front wheel F to provide a steering assist force for the front wheels. Before that
The first auxiliary pinion accompanies the rotation of the wheel pinion 25F.
The first auxiliary rack 62 moves as the 61 rotates.
The first auxiliary rack 62 accompanies the movement of the first auxiliary rack 62.
The piston 63 moves. As shown in FIG.
While the steering amount is small, the first auxiliary piston 63 separates
Since the two oil chambers 74 and 75 communicate with each other, the pressure oil is supplied to the second auxiliary chamber.
It is not supplied to the hydraulic cylinder 84 and the steering of the rear wheels
The amount is set to 0, and when traveling straight ahead and at high speed with a small steering angle.
The running stability during cornering running is improved. front wheel
When the steering amount of the vehicle increases, the first auxiliary piston 63
Movement of the moving member 124 between the two oil chambers 74 and 75 to be cut off
, The first auxiliary piston 63 moves.
When steering to one of the left and right, the first auxiliary hydraulic
The second auxiliary hydraulic cylinder 8 from one oil chamber 74 of the
4 is supplied with pressure oil to one oil chamber 96 and is steered to the other side.
If so, the other oil chamber 75 of the first auxiliary hydraulic cylinder 64
To the other oil chamber 97 of the second auxiliary hydraulic cylinder 84
Is supplied. By supplying this pressure oil, the second auxiliary piston
83 moves and accompanies the movement of the second auxiliary piston 83
As the first auxiliary rack 62 moves, the second auxiliary
The pinion 81 rotates and the second auxiliary pinion 81 rotates.
The rotation of the rear wheel pinion 25R according to the
The rear wheel can be steered by moving the
You. When this rear wheel is steered, the rear wheel control valve 30R
The hydraulic oil pressure controlled by the hydraulic cylinder 20R for the rear wheel
To provide the rear wheel steering assist force. This
To improve turning performance when driving at low speeds with large steering angles.
Is achieved. The first auxiliary piston 63 is a front wheel pinion.
Rotation of the first auxiliary pinion 61 in accordance with the rotation of the
When the first auxiliary rack 62 moves more,
It is not necessary to connect to the front wheel rack 4F, and the first auxiliary
The hydraulic cylinder 64 can be reduced in size. Furthermore, for the front wheel
The pinion 25F and the first auxiliary pinion 61 are coaxial and
Rotate along with the first auxiliary pinion 61 per unit rotation.
The amount of movement of the first auxiliary rack 62 depends on the front wheel pinion 25F.
Less than the amount of movement of the front wheel rack 4F per unit rotation
The maximum stroke of the first auxiliary piston 63 is
Can be smaller than the maximum stroke of the
Accordingly, the first auxiliary hydraulic cylinder 64 can be downsized.
Also, the piston rod of the first auxiliary hydraulic cylinder 64
It is not necessary to project the
It is not necessary to cover the protrusion with a telescopic cover. Also, the rear wheels fall into grooves or the like, making steering impossible.
If the front wheels are steered when
From the first auxiliary hydraulic cylinder 64 to the second auxiliary hydraulic system.
The hydraulic pressure supplied to the cylinder 84 increases,
Is greater than or equal to the set value, the first and second pilot check valves
When one of 113 and 114 opens, the first auxiliary hydraulic
One of the pair of oil chambers 74 and 75 of the
The other of the pair of oil chambers 96 and 97 of the cylinder 84, or
Is a pair of oil chambers 74, 75 of the first auxiliary hydraulic cylinder 64.
And a pair of oil chambers 96 of the second auxiliary hydraulic cylinder 84,
97 is in communication with one of them and the oil pressure becomes excessive
And damage to the equipment is prevented. The present invention is not limited to the above embodiment.
No. For example, in the above embodiment, the rear wheel pinion 25R
The moving amount of the rear wheel rack 4R per rotation is constant.
However, the amount of movement increases as the front wheel steering angle increases.
The rear wheel pinion 25R and the rear wheel rack 4R
May be set. According to the present invention, a four-wheel steering system for a vehicle is provided.
New large-size telescopic cover that can be reduced in size and weight
It is not necessary to perform, and the seal member of the first auxiliary piston is damaged.
Can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory view of a four-wheel steering device according to an embodiment of the present invention. FIG.
FIG. 3 is a cross-sectional view for explaining the configuration of an auxiliary piston and a first auxiliary rack.
FIG. 4 is a cross-sectional view for explaining the configuration of the auxiliary piston and the second auxiliary rack. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1. FIG. FIG. 6 is a cross-sectional view of a control valve for front and rear wheels according to an embodiment of the present invention. [Description of References] F Rack-pinion hydraulic power steering mechanism for front wheel steering R Rack-pinion hydraulic power steering mechanism for rear wheel steering 4F Rack for front wheels 4R Rack for rear wheels 20F Hydraulic cylinder for front wheels 20R Hydraulic cylinder for rear wheels 25F For front wheels Pinion 25R Rear wheel pinion 30F Front wheel control valve 30R Rear wheel control valve 61 First auxiliary pinion 62 First auxiliary rack 63 First auxiliary piston 64 First auxiliary oil Cylinder 74 and 75 the oil chamber 81 and the second auxiliary pinion 82 second auxiliary rack 83 the second auxiliary piston 84 the second auxiliary hydraulic cylinder 96 and 97 the oil chamber 124 moving member

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B62D 7/14

Claims (1)

(1) A rack and pinion hydraulic power steering system for front wheel steering, comprising a rack and pinion hydraulic power steering mechanism for front wheel steering and a rack and pinion hydraulic power steering mechanism for rear wheel steering. The mechanism controls a front wheel pinion that rotates in accordance with steering, a front wheel rack that meshes with the front wheel pinion, a front wheel hydraulic actuator that generates a front wheel steering assist force, and a hydraulic pressure that acts on the front wheel hydraulic actuator. Having a front wheel control valve,
The rear-wheel steering rack and pinion hydraulic power steering mechanism includes a rear-wheel pinion, a rear-wheel rack that meshes with the rear-wheel pinion, a rear-wheel hydraulic actuator that generates rear-wheel steering assisting force, and a rear-wheel hydraulic actuator. A first auxiliary pinion having a rear wheel control valve for controlling hydraulic pressure acting on the wheel hydraulic actuator, and rotating in accordance with rotation of the front wheel pinion; a first auxiliary rack meshing with the first auxiliary pinion; A first auxiliary hydraulic cylinder having a first auxiliary piston that moves in accordance with the movement of the first auxiliary rack, a second auxiliary pinion that rotates a rear wheel pinion in accordance with its own rotation, and a second auxiliary pinion that meshes with the second auxiliary pinion. A second auxiliary rack, and a second auxiliary hydraulic cylinder having a second auxiliary piston for moving the second auxiliary rack in accordance with its own movement. One of the pair of oil chambers partitioned by the auxiliary piston is connected to one of the pair of oil chambers partitioned by the second auxiliary piston, and the other of the pair of oil chambers partitioned by the first auxiliary piston and the second auxiliary piston. The other of the paired oil chambers is connected and the front wheel
Pinion and first auxiliary pinion are coaxial and rotate together
The unit rotation of the first auxiliary pinion.
Of the first auxiliary rack is unit rotation of the front wheel pinion.
It is smaller than the amount of movement of the front wheel rack
Communicating with a pair of oil chambers partitioned by the first auxiliary piston
Moving in accordance with the movement of the first auxiliary rack
A moving member is provided to open and close the
A four-wheel steering device for a vehicle, which is opened when the steering amount is equal to or less than a certain value .