JPH0457547B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) This invention relates to a steering device for a vehicle, and more particularly, a power steering device that assists steering of front wheels by the action of pressure fluid, and a rear wheel steering device that assists steering of the rear wheels by the action of pressure fluid. The present invention relates to a steering device in which pressure fluid generated by one pressure fluid generating means is distributed and supplied to the steering device using a diversion valve.

(Prior Art) For vehicles in recent years, steering devices capable of steering both front wheels and rear wheels have been proposed for the purpose of improving turning performance. Conventionally, as this type of steering device, for example, a compliance steer control device described in Japanese Patent Laid-Open No. 57-99470 is known.

This compliance steer control device includes a hydraulic actuation means attached to an elastic body interposed between the rear wheel suspension device and the vehicle body, and supplies hydraulic pressure to the power cylinder of the power steering device to the hydraulic actuation means. By doing so, control is performed to reduce or increase compliance steer that occurs when the vehicle is turning. That is, the rear wheels are steered by decreasing or increasing compliance steer.

This kind of compliance steer control device steers the rear wheels in the same direction as the front wheels when steering the steering wheel, setting the turning characteristics to the understeer side, and mainly aims to improve turning performance when driving at high speeds. It is.

By the way, as is well known, in the case of a power steering mechanism, in order to give the driver an appropriate steering feeling, the steering assist force generated by the power cylinder is controlled to be small in a high vehicle speed range, and the steering assist force generated by the power cylinder is controlled to be small in the high vehicle speed range. A region (dead zone) in which the power cylinder does not generate a steering assist force is set within a range where the applied steering force is minute. Therefore, low hydraulic pressure is supplied to the power cylinder of the power steering mechanism at high vehicle speeds, and no hydraulic pressure is supplied when the steering force applied to the steering wheel is small.

However, when controlling compliance steer for the rear wheels, in order to achieve more stable turning, it is desirable to generate a large compliance steer in the high vehicle speed range to greatly deflect the rear wheels. When the steering wheel is steered, it is desirable to deflect the rear wheels even if the deflection angle of the front wheels is small (the steering force applied to the steering wheel is small). For this reason, when the hydraulic actuation means of the compliance steer control device supplies hydraulic pressure to the power cylinder of the power steering mechanism, it is not possible to control the compliance steer control device with the best characteristics in terms of cornering performance. It is necessary to control the hydraulic pressure supplied to the compliance steer control device separately from the hydraulic pressure supplied to the power cylinder of the power steering mechanism.

However, the control valve used in the above-mentioned power steering mechanism and compliance steer control device and which controls the hydraulic pressure in response to the steering wheel steering normally directs the pressure oil discharged by the pump to the reservoir when the steering wheel is in the neutral position. A reflux type (center open) control valve is used. Therefore, when pressure oil is supplied from a single pump to the control valve of the power steering mechanism and the control valve of the compliance steer control device, which have different initial operating characteristics as described above, the desired initial characteristics can be obtained. The problem is that I can't do it. That is,
As mentioned above, in a steering system in which a dead zone is set in the control valve of the power steering mechanism, pressure oil is supplied by the control valve to the hydraulic actuation means of the compliance steering control device when the steering force applied to the steering wheel is very small. When this happens, the hydraulic circuit resistance on the compliance steer control device side increases, so
Pressure oil discharged by the pump flows back to the reservoir via the control valve of the power steering mechanism, and insufficient hydraulic pressure is supplied to the hydraulic actuation means of the compliance steering control device.

(Object of the Invention) This invention was made in view of the above-mentioned problems, and it is possible to control the power steering device and the rear wheel steering device with the best characteristics respectively, and to control both the power steering device and the rear wheel steering device using a single pump. The purpose is to supply pressurized fluid to the rear wheel steering device without causing any trouble, thereby making the steering device more compact and reducing manufacturing costs.

(Structure of the Invention) A steering device for a vehicle according to a first invention includes a steering gear mechanism that transmits a steering force applied to a steering wheel to a front wheel and biases the front wheel, and a pressurized fluid that pressurizes fluid in a reservoir. two control valves that control the pressure fluid generated by the pressure fluid generation means in response to the steering of the steering handle; and a pressure fluid that is controlled by one of the control valves. A vehicle steering system comprising: a power cylinder that is supplied with an auxiliary force to bias a front wheel; and an actuator that is supplied with pressure fluid controlled by the other control valve to bias a rear wheel. A dividing valve is provided to distribute and supply the pressure fluid generated by the pressure fluid generating means to the two control valves, and the dividing ratio of the dividing valve is made variable.

Further, the vehicle steering device according to the second invention includes:
A steering gear mechanism that transmits a steering force applied to a steering wheel to a front wheel and deflects the front wheel, a pressurized fluid generating means that pressurizes fluid in a reservoir to generate pressurized fluid, and the pressurized fluid generating means is generated. two control valves that control pressure fluid in response to the steering of the steering handle; a power cylinder that is supplied with the pressure fluid controlled by one of the control valves and generates an auxiliary force that biases the front wheels; and the control valve. and an actuator that biases a rear wheel by being supplied with pressure fluid controlled by the other of the valves, wherein the pressure fluid generated by the pressure fluid generation means is directed to the two control valves. a flow divider valve that distributes and supplies pressure fluid at a flow ratio of , and at least one of the pressure fluid supplied from the flow divider valve to the one control valve or the pressure fluid supplied from the flow divider valve to the other control valve to the reservoir. The reservoir is provided with a bypass path that flows back to the reservoir, and a flow rate control valve that controls the flow rate of the pressure fluid that flows back to the reservoir via the bypass path.

According to the vehicle steering device according to the first invention,
Since the flow rate of the pressurized fluid supplied to each control valve is secured by the flow divider valve, each can be controlled independently.For example, an actuator that deflects the rear wheels without operating the power cylinder of the front wheels can be used. Even when operating only the steering wheel, sufficient pressure fluid is supplied to this actuator, and it is possible to reliably deflect the rear wheels in accordance with the steering of the steering wheel.

Further, according to the vehicle steering device according to the second invention, similarly to the vehicle steering device according to the first invention, it is possible to reliably bias the rear wheels according to the steering of the steering wheel, and further, By controlling the pressure fluid that flows back through the bypass path using a flow control valve, it is possible to obtain arbitrary steering characteristics. In other words, by controlling the flow rate of the pressure fluid flowing through the bypass path depending on the vehicle speed, for example, it is possible to set characteristics that depend on the vehicle speed in the steering system of this vehicle. If the flow rate can be changed manually,
It is possible to limit the steering characteristics to characteristics desired by the driving vehicle or characteristics optimal for the vehicle to which the steering device is installed, increasing its versatility.

(Example) Hereinafter, an example of the first invention will be described based on the drawings.

FIG. 1 is a diagram showing a first embodiment of the first invention, and shows an outline of a vehicle steering system.

First, to explain the configuration, 11 is the vehicle body, 12
R and 12L indicate the front wheels, and 13R and 13L indicate the rear wheels. The front wheels 12R, 12L are connected to the knuckle arms 14R, 14L and the side rod 1, respectively.
It is connected to the end of the rack 16 via 5R and 15L. A pinion 17 meshes with the rack 16, and the pinion 17 is connected to a steering handle 19 via a steering shaft 18. The rack 16 and pinion 17 constitute a steering gear mechanism 20.

The rear wheels 13R, 13L are swingably supported by a rear wheel suspension member 22 via semi-trailing arms 21R, 21L, respectively. The rear wheel suspension member 22 is elastically supported at both ends of the vehicle body 11 by pins 24R, 24L via insulator rubbers 23R, 23L, and the differential gear housing 25 is fixed by bolts (not shown). ing.
This differential gear housing 25 also
Also, the pin 27 is inserted through the insulator rubber 26.
It is elastically supported to the vehicle body 11 by. Note that 28R and 28L are drive shafts that connect the differential gear in the differential gear housing 25 and the rear wheels 13R and 13L.

Reference numeral 29 denotes a pump (pressure fluid generating means) that pressurizes and discharges the working fluid in the reservoir 30, and the discharge port of the pump 29 is connected to the inlet port of the diversion valve ₃₁ via a pipe P1. The diverter valve 31 is of a well-known type, and its two outlet ports are connected to a first control valve 32 provided in the steering shaft 18 by pipes P ₂ and P ₃ , respectively.
It is connected to the second control valve 33 to distribute and supply the pressure fluid discharged by the pump 29 at a predetermined distribution ratio.

The first control valve 32 is connected to the reservoir 30 through a pipe P ₈ , and the power cylinder 34 provided in the rack 16 is connected through pipes P ₄ and P ₅ to operate the pressure fluid supplied from the flow dividing valve 31 . It is controlled and supplied to the power cylinder 34 according to the steering of the steering wheel 19 (in the embodiment, the steering force applied to the steering wheel 19). That is, this first control valve 32 has four variable orifices 32a, 32b, 32c, and 32d whose flow path areas change according to the steering force applied to the steering handle 19. 32c, 32d
to control the pressure fluid. power cylinder 34
A piston 36 fixed to a rack 16 is slidably fitted into a cylinder body 35 provided on the vehicle body 11, and two fluid chambers 37 and 38 are defined. This power cylinder 34 includes a fluid chamber 37,
A steering assist force is generated in accordance with the pressure difference at 38 to press the rack 16. These pump 29, reservoir 30, first control valve 32 and power cylinder 34
constitutes a well-known power steering device 39.

The second control valve 33 is connected to four actuators 40a, 40b, 4 interposed between the rear wheel suspension member 22 and the vehicle body 11 via pipes _P6 , _P7 .
0c and 40d, and is also connected to the server 38 via piping _P9 . This second control valve 33
Similarly to the first control valve 32 described above, the four variable orifices 33a, 33b, whose flow path area changes in response to the steering force applied to the steering handle 19,
33c, 33d, and controls the pressure fluid supplied from the flow dividing valve 31 according to the steering force applied to the steering handle 19 to control each actuator 40a, 40.
b, 40c, and 40d. The actuators 40a, 40b, 40c, 40d are connected to the vehicle body 11 and the rear wheel suspension member 22 by pin joints, and deform the insulator rubbers 23R, 23L by the action of pressure fluid supplied from the second control valve 33. The rear wheel suspension member 22 is rotated around the pin 27. That is, actuators 40a, 40b, 40
c and 40d deflect the rear wheels 13R and 13L by rotating the rear wheel suspension member 22. These pumps 29, reservoirs 30, second
Control valve 33 and actuators 40a, 40
b, 40c, and 40d constitute a compliance steer control device (rear wheel steering device) 41. Note that this compliance steer control device 41 is described in detail in Japanese Patent Laid-Open No. 57-99470, so a description thereof will be omitted hereafter.

Next, the effect will be explained.

The steering system of this vehicle includes front wheels 12R, 1 of the vehicle.
2L and rear wheels 13R, 13L using steering wheel 1
The power steering device 39 generates a steering assist force to bias the front wheels 12 in response to the steering of the front wheels 12.
The compliance steering control device 41 assists the steering handle 19 that steers the wheels R and 12L, and deflects the rear wheels 13R and 13L in the same direction as the front wheels 12R and 12L in response to the steering of the steering handle 19.
As described above, in the power steering device 39, a dead zone is set in which no steering assist force is generated when the steering force applied to the steering wheel 19 is very small.

When the steering handle 19 is not being steered now, the respective first control valves 32 and second control valves 33 are operated by the respective variable orifices 32a, 32.
b, 32c, 32d and variable orifice 33
Since a, 33b, 33c, and 33d have the same opening degree, the pressure fluid discharged by the pump 29 is
The flow is distributed to each control valve 32, 33 by a dividing valve 31, and the reservoir 3 is distributed through each control valve 32, 33.
It is refluxing to 0.

Here, a small amount (within the dead zone) is applied to the steering handle 19.
When a steering force of (for example, a force for steering to the right, the same applies in the following description) is applied, the variable orifices 33a and 33c of the second control valve 33 are narrowed in accordance with the steering force, and the variable orifice 33b is , 33d are opened in response to the steering force,
Since a dead zone is set in the power steering device 39, each variable orifice 3 of the first control valve 32
The opening degrees of 2a, 32b, 32c, and 32d do not change. For this reason, the pipe P ₂ from the diverter valve 31
The pressure fluid supplied to the first control valve 32 through
The pressure fluid is returned to the reservoir 30 from the first control valve 32 via the pipe P ₈ without being supplied to the power cylinder 34, and the second control valve 33 returns the pressure fluid supplied from the diverter valve 31 via the pipe P ₃ to the reservoir 30. Control is performed in response to the steering force, and high pressure fluid is supplied to the actuators 40b and 40d via the pipe _P7 , while low pressure fluid is supplied to the actuators 40a and 40c via the pipe _P6 . Therefore, front wheel 1
2R and 12L are biased to the right only by the steering force transmitted from the steering wheel 19 via the steering gear mechanism 20, and the rear wheels 13R and 13
L is actuator 40a, 40b, 40c, 4
0d causes it to shift to the right. At this time, since the second control valve 33 supplies high-pressure fluid to each actuator 40b, 40d, the fluid circuit resistance on the second control valve 33 side increases. Supply of pressure fluid at a predetermined flow rate is ensured. Therefore, the actuator 40
The rear wheels 13R, 13L can be deflected reliably without decreasing the fluid pressure supplied to the wheels b, 40d.

Next, when the steering force applied to the steering handle 19 increases, the variable orifices 32b and 32d of the first control valve 32 are also narrowed in accordance with the steering force, and the variable orifices 32a and 32c are opened, and the power cylinder High pressure fluid is supplied to the fluid chambers 38 of 34 . Therefore, the power cylinder 34 generates a steering assist force to press the rack 16 and reduce the steering effort of the steering handle 19. Also,
The second control valve 33 has a variable orifice 33a,
The flow path areas of 33b, 33c, and 33d change to a greater extent, allowing higher pressure fluid to be delivered to the actuator 4.
In order to supply to 0b, 40d, rear wheels 13R, 13
The deflection angle of L becomes larger. At this time, the flow rate of the pressure fluid supplied to each control valve 32, 33 is ensured by the flow divider valve 31 at a predetermined amount according to the flow divider ratio. They do not interfere with each other, and each control is performed according to the steering force.

As described above, the pressure fluid discharged by one pump 29 is distributed to the flow dividing valve 31 and distributed to each control valve 32, 3.
3, the power steering device 39
and the compliance steering control device 41 operate independently, making it possible to obtain better steering performance.

In addition, by distributing the pressure fluid discharged by the pump 29 by the flow dividing valve 31, the power steering device 39 and the compliance steering control device 41
Since there is no need to provide a separate pump for each, the steering device can be made smaller and its manufacturing cost can be reduced.

2 and 3 show a second embodiment of the first invention.

In this second embodiment, the pressure fluid discharged by the pump 29 is distributed by a variable distribution ratio diversion valve 42, and the distribution ratio of the variable distribution ratio diversion valve 42 is controlled in accordance with the vehicle speed. Note that the same parts as in the first embodiment described above are given the same numbers.
The explanation will be omitted.

In FIG. 2, reference numeral 42 indicates that the pressure fluid discharged by the pump 29 is transferred to the first control valve 32 and the second control valve 33.
This is a variable ratio diversion valve that distributes the flow to
The shunt ratio changes depending on the current value applied to.
The control unit 43 includes a vehicle speed sensor 44 that detects the vehicle speed and outputs a signal to display the vehicle speed V.
is connected. This control unit 4
3 changes the current value supplied to the solenoid 42a according to the vehicle speed V to adjust the flow division ratio of the flow dividing valve 42 to the vehicle speed V.
Control accordingly.

As the variable flow ratio dividing valve 42, for example, one shown in FIG. 3 is used. In the same figure, 4
5 is a valve housing in which a hole 45a is formed, and this housing 45 has an inlet port 4 that opens to the hole 45a and is connected to the pump 29.
6, and each control valve 3 opens to the hole 45a.
Two outlet ports 47,4 connected to 2,33
8 is formed. Hole 4 of housing 45
A pair of spools 49 and 50 are slidably inserted into the hole 45a, and both openings of the hole 45a are inserted into the plug 5a.
1, 52, these spools 49,
50 and the plugs 51, 52, a spool 49,
a spring 53 that biases 50 in the direction of approaching;
54 has been reduced. These plugs 51,5
2 is a substantially cylindrical member 55 in which holes 51a and 52a communicating with the outlet ports 47 and 48 are formed, respectively, and a main hole 55a and two control orifices 55b and 55c are formed between opposing ends.
is being held in place.

Each of the spools 49, 50 has a hollow shape with holes 49a, 50a opening on the side end surfaces of the plugs 51, 52, and defines fluid chambers 56, 57 between the spools 49, 50 and the plugs 51, 52. substantially “L”-shaped hook portions 49b that engage with each other at each end thereof;
50b is integrally formed. Furthermore, protrusions 49c, 50c are formed on each spool 49, 50, and the grooves set by the protrusions 49c, 50c are capable of slidingly contacting the inner surface of the member 55 in a substantially liquid-tight manner. 55b and 55c define open chambers 58 and 59. Further, each spool 49, 50 has chambers 58, 59 and fluid chambers 56, 5.
7, and holes 49e, 50e that open to the fluid chambers 56, 57 and can communicate with the holes 51a, 52a of the plugs 51, 52 are formed. The holes 49e, 50e and the holes 51a, 52a of the plugs 51, 52 form variable orifices 6, 61 whose flow area is changed by displacement of the spools 49, 50. In addition, 62
is a spring that is compressed between the opposing ends of the spools 49, 50 and biases the spools 49, 50 in the direction of separating them.

Also, one control orifice 55c of the member 55
, a solenoid 42 provided in the housing 45
A needle valve 63 driven by a is loosely inserted. This needle valve 63 is driven by the solenoid 42a to change the flow path area of the control orifice 55c. Note that the solenoid 42a is
It is connected to the control unit 43 mentioned above.

This variable flow ratio dividing valve 42 has an inlet port 4.
The needle valve 63 controls the fluid pressure flowing into one of the fluid chambers 57 from the needle valve 63 by changing the flow path area of the control orifice 55c, and controls the flow division ratio. That is, since each of the spools 49, 50 of this flow dividing valve 42 is displaced in response to the fluid pressure in the fluid chambers 56, 57 and the elastic force of the springs 53, 54, 62, The flow path area of the variable orifices 60, 61 changes accordingly, and the flow rate flowing out from each outlet port 47, 48 is maintained at a predetermined division ratio, that is, the division ratio set by the control unit 43.

Next, the action will be explained.

In such a steering device, the pressure fluid Q discharged by the pump 29 is controlled in accordance with the vehicle speed V,
For example, it is supplied to each control valve 32, 33 with flow characteristics as shown in FIGS. 6a and 6b or 7a and 7b. That is, the first control unit 43 of the power steering device 39 controls the amount of pressure fluid Q 1 supplied to the control valve 32 to decrease at high vehicle speeds, and also controls the amount of pressure fluid Q ₁ supplied to the control valve 32 to decrease at high vehicle speeds, and also controls the amount of pressure fluid Q 1 supplied to the control valve 32 to decrease at high vehicle speeds. The amount of pressure fluid Q ₂ to be supplied is controlled to increase at high vehicle speeds.
However, the amount of fluid Q discharged by the pump 29 is Q=
There is a relationship of Q ₁ + Q ₂ . Therefore, the pressure of the pressure fluid supplied to the power cylinder 34 of the power steering device 39 decreases in the high vehicle speed range, and the steering assist force generated by the power cylinder 34 becomes small, making it difficult for the driver to obtain a good steering feeling. can. Conversely, the actuators 40a, 40b, 40 of the compliance steer control device 41
Since the pressure of the pressurized fluid supplied to the rear wheels 1 and 40d increases in a high vehicle speed range, the rear wheels 1 are
The deflection angles of 3R and 13L become larger, and the turning performance of the vehicle improves.

FIG. 4 shows a third embodiment of the first invention.

In this embodiment, the dividing ratio of the variable dividing ratio type diverting valve 42 can be changed by manual operation. Incidentally, the same parts as in the second embodiment are given the same numbers, and the explanation thereof will be omitted.

As shown in Fig. 4, the control unit 4
3 is connected to an operation switch 64. This operation switch 64 is provided near the driver's seat and can be operated by the driver, and by operating this operation switch 64, the flow division ratio of the flow dividing valve 42 is changed.

In this steering device, when the driver operates the operation switch 44, the control unit 43
energizes the solenoid 42a of the flow dividing valve 42, and the flow dividing ratio is changed. Therefore, the turning characteristics and steering characteristics of the vehicle can be set to the characteristics desired by the driver. Furthermore, even when this steering device is installed on a different type of vehicle, by operating the operation switch 64, it is possible to set the steering characteristics and turning characteristics to values that are optimal for the vehicle. It can be attached to other types of vehicles without modifying the steering system, increasing its versatility.

Next, an embodiment of the second invention will be described based on the drawings.

FIG. 5 is a diagram showing an embodiment of the second invention. Note that the same parts as in the first embodiment and the second embodiment of the first invention described above are given the same numbers, and the explanation thereof will be omitted.

First, to explain the configuration, P ₁₀ is connected to pipe P ₂ and pipe
The first bypass pipe (bypass path) connected to P ₈ , P ₁₁
is a second bypass pipe (bypass path) connecting pipe P ₃ and pipe P ₉ , and these first bypass pipes P ₁₀
Well-known first and second pressure compensation type flow control valves 65 and 66 are interposed in the second bypass pipe _P11 , respectively. These first and second flow control valves 6
5 and 66 are the control unit 4, respectively.
It has solenoids 65a and 66a which are connected to each other. The control unit 43 is connected to a vehicle speed sensor 44 and controls each flow control valve 65, 66 in accordance with the vehicle speed V.

Next, the effect will be explained.

Even in this steering device, each control valve 32, 33
controlling the pressure fluid supplied to the vehicle in accordance with the vehicle speed V;
For example, the flow rate characteristics are controlled as shown in FIGS. 6a and 6b or 7a and 7b. Therefore, as described in the second embodiment of the first invention, the power steering device 39 and the compliance steering control device 41 are configured to be responsive to vehicle speed, and the turning performance of the vehicle is improved. You can feel the steering.

In the steering device according to the second invention,
The flow rate of the pressure fluid supplied to each power steering device 39 and compliance steer control device 41 can be independently controlled without being restricted by the discharge amount of the pump 29. That is, each control valve 32,
The flow rate of the pressure fluid supplied to the flow dividing valve 31
Since the pressure fluid distributed at a predetermined diversion ratio is further controlled by flowing back to the reservoir 30 by the flow rate control valves 6 and 66, it is possible to reduce the amount of fluid supplied from the diversion valve 31 regardless of the amount of fluid supplied from the diversion valve 31. This expands the controllable range.

(Effects of the Invention) As explained above, according to the first invention, the fluid discharged by the pump is distributed and supplied by the flow divider valve, so that the front wheel power steering device and the rear wheel steering device each have their own power steering device. They no longer influence each other and operate reliably, improving reliability. Furthermore, since there is no need to provide a plurality of pumps, the entire device can be made smaller and its manufacturing cost can be reduced.

Furthermore, in the second embodiment of the first invention, the diverter valve is configured to have a variable diverter ratio and the diverter ratio is controlled in accordance with the vehicle speed, so it is possible to obtain a good steering feel. Furthermore, in the third embodiment, the flow dividing ratio of the flow dividing valve can be changed manually, so that the driver can obtain desired or vehicle-specific steering characteristics and turning characteristics. be able to.

Furthermore, in the second invention, since the fluid discharged by the pump is distributed by the flow dividing valve and then further controlled by the flow rate control valve, each can be controlled separately, and the controllable range is expanded.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first embodiment of a vehicle steering device according to the first invention, FIG. 2 is a schematic diagram showing a second embodiment of the vehicle steering device according to the first invention, and FIG. FIG. 4 is a schematic diagram showing a third embodiment of the vehicle steering system according to the first invention; FIG. A schematic diagram showing an embodiment of such a steering system for a vehicle, FIGS. 6a and 6b are flow rate characteristic diagrams each showing one aspect of control, and FIGS. 7a and b are each showing another aspect of control. FIG. 11...Vehicle body, 12R, 12L...Front wheel, 13
R, 13L...Rear wheel, 19...Steering handle, 2
0... Steering gear mechanism, 29... Pump (pressure fluid generating means), 30... Reservoir, 31...
...Diversion valve, 32, 33... Control valve, 34... Power cylinder, 39... Power steering device,
40... Actuator, 41... Compliance steer control device, 42... Variable dividing ratio diversion valve, 43... Control unit, 44... Vehicle speed sensor, 64... Operation switch, 65, 66...
...Pressure compensation type flow control valve, P ₁₀ , P ₁₁ ...Bypass pipe (bypass path).

Claims (1)

[Scope of Claims] 1. A steering gear mechanism that transmits the steering force applied to the steering wheel to the front wheels and deflects the front wheels; a pressurized fluid generating means that pressurizes fluid in a reservoir to generate pressurized fluid; two control valves that control the pressure fluid generated by the pressure fluid generation means in response to the steering of the steering handle; and the pressure fluid controlled by one of the control valves is supplied to provide an auxiliary force for deflecting the front wheels. In the vehicle steering system, the vehicle steering system includes a power cylinder that generates pressure fluid, and an actuator that biases a rear wheel by being supplied with pressure fluid controlled by the other control valve, wherein the pressure fluid generated by the pressure fluid generation means is A steering system for a vehicle, characterized in that a flow divider valve is provided to divide and supply the flow to the two control valves, and the flow divider ratio of the flow divider valve is variable. 2. The diverting valve has a diverting ratio controlled in accordance with the vehicle speed, and in a high vehicle speed range, the amount of pressure fluid supplied to the one control valve is reduced compared to the amount of pressure fluid supplied to the other control valve. A vehicle steering system according to claim 1, characterized in that: 3. The vehicle steering system according to claim 1, wherein the flow dividing ratio of the flow dividing valve can be changed by manual operation. 4. A steering gear mechanism that transmits the steering force applied to the steering wheel to the front wheels and deflects the front wheels, a pressurized fluid generating means that pressurizes fluid in a reservoir to generate pressurized fluid, and the pressurized fluid generating means generates two control valves that control the pressurized fluid corresponding to the steering of the steering handle; a power cylinder that is supplied with the pressure fluid controlled by one of the control valves and generates an auxiliary force that biases the front wheels; An actuator for biasing a rear wheel by being supplied with pressure fluid controlled by the other of the control valves, wherein the pressure fluid generated by the pressure fluid generation means is supplied to the two control valves. a flow divider valve that distributes and supplies the flow at a predetermined flow ratio; and at least one of the pressure fluid supplied from the flow divider valve to the one control valve or the pressure fluid supplied from the flow divider valve to the other control valve. A steering device for a vehicle, comprising: a bypass path that flows back to the reservoir; and a flow control valve that is provided in the bypass path and controls the flow rate of pressure fluid that flows back to the reservoir via the bypass path.