JPS60166564A - Four wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To enhance the critical characteristic upon cornering to improve the characteristic of control, by changing the steering ratio of rear wheels when a vehicle speed detected by a vehicle speed sensor and a lateral acceleration obtained by the hydraulic pressure of a cylinder in a power steering unit exceed set values, respectively. CONSTITUTION:When a controller 23 determines that a vehicle speed detected by a vehicle speed sensor 21 and a lateral acceleration obtained by the hydraulic pressure of a cylinder detected by a hydraulic pressure sensor 22 exceed set values, respectively, a piston 16b in a same/reverse changeover unit 16 is moved inward by an actuator to communicate right and left chambers in a front cylinder 7 with right and left chambers in a rear cylinder 15, respectively. In this condition when a steering wheel is further turned so that the volume of the left chamber of the front cylinder 7 is reduced, oil discharged at this time flows into the left chamber of the second rear cylinder 15 to move a piston 15b rightward. Accordingly, as the steering angle is increased, rear wheels decreases their steering angle to enhance the critical angle upon cornering.

Description

[Detailed Description of the Invention] Field of Industrial Application) The present invention relates to a V-wheel steering system for a vehicle that also steers the rear wheels in accordance with the steering of the front wheels, and in particular, in accordance with the lateral acceleration during turning. The present invention relates to a rear wheel steering system for a vehicle that controls the steering angle of the rear wheels.

(Prior art) When a vehicle turns at high speed, the sideslip angle of the driving tires becomes larger than the sideslip angle of the non-driving tires, as shown in FIG. Understeering characteristics occur, and as shown by the solid line in the figure, oversteering characteristics occur in rear-wheel drive vehicles.

It is generally well known that this unmeasuring tendency and oversteering tendency rapidly increase as the lateral acceleration applied to the vehicle increases, and that the vehicle cannot be controlled beyond a certain lateral acceleration. be.

Today, a nine-wheel steering system is being developed that steers the rear wheels following the steering of the front wheels of a vehicle (for example, see Japanese Patent Application Laid-Open No. 7-70771I).

In this nine-wheel steering system, the rear wheels are normally steered in the same phase direction as the front wheels when the vehicle is gradually decreasing in height, so that, for example, changing lanes on a high-speed retreat can be performed extremely smoothly with good running stability. In addition, the rear wheels are steered in the opposite phase to the front wheels in the low vehicle speed range, making it possible to reduce the turning radius, and this seven-wheel steering system is attracting attention as an excellent steering system.

However, the conventionally known T-wheel steering system? Since the rear wheel steering angle is determined relative to the front wheel steering angle depending on the vehicle speed or the corresponding front wheel steering angle, for example, when driving at high speed, the front wheels and rear wheels are steered in the same phase direction. There is a problem in that when the vehicle is subjected to high pressure and lateral acceleration, the sideslip angle of the driving tires becomes larger than the sideslip angle of the non-driving tires, making it impossible to control the vehicle in the same way as a conventional two-wheel steering vehicle. Ta.

In order to solve this problem, the inventor of the present invention changed the ratio of the steering angle of the rear wheels to the steering angle of the front wheels in accordance with the lateral acceleration received by the bundle, thereby reducing the understeering that occurs during high-speed turns. We have proposed a seven-wheel steering system for vehicles that eliminates oversteering characteristics and improves limit characteristics during cornering. However, the acceleration detectors known today that detect lateral acceleration have poor responsiveness, and the steering angle of the rear wheels is not immediately corrected and changed during high-speed turns.
There was a problem that the vehicle could not be controlled sufficiently.

(Objective of the Invention) Therefore, the object of the present invention is to vary the ratio C of the steering angle of the rear wheels to the steering angle pressure of the front wheels (this is called the steering ratio) in an extremely responsive manner in accordance with the lateral acceleration that the vehicle receives. Therefore, it is an object of the present invention to provide a seven-wheel steering system for a vehicle that has high limit characteristics during cornering and good steering characteristics.

(Structure of the Invention) A seven-wheel steering device for a vehicle according to the present invention includes a power steering device that steers the front wheels, and a predetermined steering ratio according to the steering angle of the front wheels steered by the power steering device in the same phase direction. a rear wheel steering device that steers the rear wheels, a hydraulic pressure sensor that detects the cylinder hydraulic pressure of the nozzle steering device, and a lateral acceleration obtained from the cylinder hydraulic pressure detected by at least this hydraulic sensor that exceeds the set lateral acceleration l & The case is characterized in that it includes a correction means for changing the steering ratio, and when the front wheels are steered, the cylinder oil pressure generated in the power cylinder of the power steering device is detected, and at least the detected cylinder oil pressure is used to adjust the vehicle body. The system essentially determines whether the lateral acceleration received by the vehicle is greater than or equal to the set acceleration, and if the acceleration is greater than or equal to the set acceleration, the vehicle speed or the steering ratio of the front wheels corresponding to the vehicle speed is changed. Since the steering ratio of the rear wheels can be changed simultaneously with the occurrence of lateral acceleration without causing a delay in response, high limit characteristics and good handling characteristics can be obtained during cornering.

Cylinder oil pressure refers to the oil pressure generated in the power cylinder when the front wheels are steered when a power steering device is used as a front wheel steering device. This cylinder oil pressure is dependent on the steering angle of the front wheels. There is a prescribed relationship;
The steering angle of the front wheels can be adjusted by detecting the cylinder oil pressure.

If the vehicle speed and the front wheel steering angle determined by the cylinder oil pressure are vl θ and -■, respectively, the lateral acceleration G can be expressed as G-αv2θH (1) in a steady state, and therefore the determined steering angle θH1 vehicle speed V
The lateral acceleration is calculated according to equation (1) from Detected steering angle 08 without starting spring
It is possible to determine whether the lateral acceleration obtained from the % vehicle speed V is greater than or equal to the set acceleration.

In addition, in a transient state when the steering wheel is being operated, the lateral acceleration can be expressed as 3xαv2θH+ / e H(2), taking the temporal change in the front wheel steering angle as an expression, and the front wheel steering angle is When a temporal change occurs, it may be determined whether the lateral acceleration is greater than or equal to the set acceleration using equation (2). Even when the magnitude of the lateral acceleration is determined using equation (2), the lateral acceleration is not actually calculated, but each detected value, that is, the predetermined value of the vehicle speed v1, the front wheel steering angle θH, and the temporal change in the front wheel steering angle θH. As described above, it is possible to determine whether the lateral acceleration is greater than or equal to the set acceleration by determining the magnitude relationship with the value.

In addition, when the vehicle speed V is estimated by the front wheel steering angle, that is, in the present invention, the rack reaction force, in the above (1) and (2), a function f(θ,
) is assigned.

When it is detected that the lateral acceleration is equal to or higher than the set lateral acceleration, the ratio of the rear wheel steering angle to the front wheel steering angle, that is, the steering ratio is changed. In a front-wheel drive vehicle or a nine-wheel drive vehicle in which driving force is distributed to the front wheels, the steering ratio is normally changed in a direction that reduces the steering ratio so as to eliminate the understeering characteristic.

In a rear-wheel drive vehicle or a wide-wheel drive vehicle in which driving force is distributed to the rear wheels, the steering ratio is changed to increase so as to eliminate the oversteering tendency.

However, it is possible to change a vehicle with understeering characteristics to a vehicle with oversteering characteristics to give it sportiness, or conversely, to change a vehicle with oversteering characteristics to a vehicle with understeering characteristics to improve stable maneuverability. It is also possible to have a vehicle with

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic diagram of a first embodiment of the present invention. A front wheel steering system 2 that steers the front wheels IL and IR includes a steering wheel 3 and a steering device 4 that converts the steering angle of the steering wheel 3 into a reciprocating motion in the vehicle width direction and transmits it. and the proximal end is the power steering device 4
left and right tie rods 5.5' connected to each end of the rack 4a moved by the
At the tip of the knuckle arm 6.6', the other end is connected to the left and right front wheels IL and IR, respectively, and the left and right tie rods 5.57
The left and right front wheels IL and IR are steered left and right by reciprocating in the vehicle width direction. The nine-wheel steering system f4 is equipped with a pair of nine-wheel cylinders 4b, and when oil flows into the four-wheel cylinders 4b in accordance with the operation of the steering wheel 3, the front wheel IL is adjusted.
, the IR is steered.

A front cylinder 7 is installed approximately in the center of the front wheel steering system 20 rack 4a. This front cylinder 7
includes a cylinder case 7a fixed to the vehicle body, a piston 1b provided integrally with the rack 4a and slidably fitted into the cylinder case 7a, and the piston 7.
A piston 7b is provided in conjunction with the rack 4b of the front wheel steering system 2.
The left ventricle 7c and the right ventricle 1d are configured to change in volume by moving in the vehicle width direction (left-right direction).

On the other hand, reference numeral 8.8' denotes a wheel support member that rotatably supports the left and right rear wheels 9L, 9R.
, 9R are connected with lateral links 10.10' and 11.11' as front and rear links S@ for steering the vehicle.

The left and right front lateral links 10.10' are connected by a link-shaped first connecting member 12 between their inner ends, and the left and right rear lateral links 11.11' are also connected by a first link between their inner ends. The left and right rear wheels 9L and 9R are connected by a connecting member 13, and the left and right rear wheels 9L and 9R are steered through the wheel support member 8 with the movement of the front and rear lateral links 10 and 110 in the vehicle width direction (left and right direction). It is supported so that it can be steered centrally.

Furthermore, the first and second connecting members 12.13 include:
A pair of first and second rear cylinders 14 and 15 are provided that reciprocate the first connecting member 12 and the second connecting member 13 in opposite directions. These 14.15 rear cylinders each have a cylinder case 14a fixed to the vehicle body.

15a, pistons 14b, 151) provided integrally with the connecting members 12, 13 and slidably fitted into these cylinder cases 14a, 15a, and these pistons 14
The left ventricle 14cb15c and the right ventricle 14d, 15d are partitioned by b, i5b, and the left and right ventricles 14cs14rJs15c, 15d are provided with return springs 14e, 148', 15θ symmetrically, respectively.
, 158' are reduced. One end of each of these return springs 14e114e', 158% 15e' abuts on each inner end surface of the cylinder cases 14a, 15a, and the other end is a press plate 14 provided on each connecting member 12.13.
f, 14f', 15f, and 15f'. These pressing plates 14f, 14f', 15f1151' are annular retaining pieces 14g integrally provided on the connecting parts U12, 13.
, 14g', 15g, 15g', and is regulated by stopper pieces 14h, 14h', tsh, tsh' provided integrally with the cylinder cases 14a, 15aK, thus forming a trap. Part 12.13 or piston 14b.

15b to return spring 14e, 14θ1115θ
While being suppressed and held in the neutral position with a set load by b15e', the connecting member 12.13 is reciprocated in the left-right direction in accordance with the left-right movement of the pistons 14b and 15b, thereby forming the front and rear ragral links 10.10. ', 11.
The left and right rear wheels 9L and 9R are configured to be steered via the steering wheel 11'.

An oil passage 17.17' communicating with the left and right chambers 7c and 7d of the front cylinder 7 is connected to an in-phase and reverse-phase switching device 16.16.
' cylinder j6ah16a'. Pistons 161), 16b' are fitted into the cylinders tea, 16a' of the switching devices 16, 16' so as to move across the openings of the oil passages 17, 17'. These pistons 16b, 16b' cause the cylinders 16a, 16a' to have an inner chamber 16cs16C'b and an outer chamber 16d.
, lad'. The inner chambers 16c and 116C' are connected to the first rear cylinder left and right chambers 14c and 14d, respectively, and an oil passage 18118'.External character 1
6d and 16d' are connected to the left and right chambers 15c and 156 of the consulting palm cylinder, respectively, by oil passages 19 and 19'.

Piston 16b, 16b of switching device ft16.16'
' is moved in the width direction of the vehicle body across the oil passage 17.17' by the actuators 16e and 160'.
8.18' or 19.19'. Furthermore, a steering angle adjustment device [20, 20' is interposed in the oil passage 17% 17'. The steering angle adjusting device 20, 20' includes oil chambers 20a, 20a', and pistons 20b, 20b' are movably fitted into the oil chambers 2oa, 20a'. These pistons 20b, 20t)' are biased inwardly by a spring 20C5200', but this spring 20c,
The biasing force of 20c' is variably controlled by actuators 20d and 20d' depending on the vehicle speed. In addition, the actuators 16θ and 16e' of the in-phase and negative phase switching device 16.1B' and the actuator 20d of the steering angle adjustment device 20.20'
.

The vehicle speed sensor 21 is controlled by a controller 23 which inputs a vehicle speed deviation and a hydraulic signal detected by a hydraulic pressure sensor 22 which detects the cylinder hydraulic pressure of the power cylinder 4b of the power steering device 4.

The vehicle T-wheel steering system configured as described above operates as follows.

Vehicle speed sensor 2 detects that the vehicle is traveling at an extremely low speed.
1, the actuator 206% 20d' is controlled by the controller 23 to set the biasing force of the spring 20cs20C' disposed in the steering angle adjustment device 20% 20' to be larger than the biasing force of the return spring 14θ. ing. Therefore, even if oil pressure is applied to the oil chambers 20a, 20a', the pistons 20b, 201)' tend to move outward, and are therefore discharged from the front cylinder T when the steering wheel 3 is operated. Oil is sent to the rear cylinders via the in-phase and out-of-phase switching devices 16 and 16';
The actuator 16eb16e' of 1B' is controlled by the controller 23 to move each piston inward, and the left chamber γC and the right chamber 7d of the front cylinder 1 are connected to the left chamber 15c and the right chamber of the second rear cylinder 15. Room 15d
is connected to. When the steering device 2 is operated, the volume of the left chamber 7c of the front cylinder 7 decreases, and this amount of oil is discharged, and this discharged oil is inserted into the left chamber 15c of the rear cylinder 15. However, since the volume change rate of the rear cylinder due to the front cylinder 1 is increasing, the ratio of the steering angle of the rear tire 9L%9R to the steering angle of the front tires IL and IR is large, and the turning radius is increased. has been made smaller, making it easier to turn.

As the vehicle speed increases, the biasing force of the springs 20c and 2Qc' disposed in the steering angle adjustment device 20° 20' becomes smaller as the actuators 20d and 2Qd' are controlled by the controller 23, so that the rear cylinder 15 exerted by the front cylinder T becomes smaller. The volume change rate decreases, and the ratio of the front wheel steering angle to the rear wheel steering angle decreases.

When driving at medium or high speeds, the output of the vehicle speed sensor is used to control the in-phase and reverse-phase switching [1B, 16' each piston 16b, 16bH actuator 16e.

16θI is moved outward under the control of the controller 23, and the left chamber 7c and right chamber 7 of the front cylinder 7
d are the left chamber 14c and right chamber 1 of the first rear cylinder, respectively.
4d. In this state, when the steering wheel 3 is operated and the volume of the left chamber 7c of the front cylinder T decreases, oil is discharged by this amount. This oil flows into the left chamber 14c of the first rear cylinder 14,
The rear tires 9L and 9R are steered in the same phase direction as the front tires IL and IP are steered. At this time, in the steering angle adjusting device 20, 20' ((springs 20c, 2
By controlling the relationship between the biasing force of 0C' and the biasing forces of springs 14θ and 14θl provided in the first rear cylinder, front wheel steering is achieved by changing the volume change rate of the 11th cylinder 14 using the front cylinder T. The ratio between the angle and the rear wheel turning angle can be changed depending on the vehicle speed. Among these, when driving at high speed, the spring 20 increases as the vehicle speed increases.
By increasing the biasing force of C1200', the rate of change in volume of the rear cylinder 14 by the front cylinder 7 is increased.

The vehicle speed detected by the vehicle speed sensor 21 and the oil pressure sensor 2
If the controller 23 determines that the lateral acceleration applied to the vehicle is greater than or equal to the set lateral acceleration based on the above-mentioned formula based on the cylinder oil pressure detected by the cylinder oil pressure detected by the cylinder oil pressure detected by the cylinder oil pressure detected by the cylinder oil pressure detected by the cylinder pressure 2, the controller 23 determines that the lateral acceleration applied to the vehicle is greater than or equal to the set lateral acceleration. In this case, each piston 16b of the in-phase and anti-phase switching device 113.16'
, 18b' are actuators 16θ, 16e', respectively.
is moved inward by the left chamber 7c of the front cylinder T.
s Right ventricle 7d and left ventricle 1 of No. 1 cylinder 15, respectively.
5 and the right ventricle 15d. In this state, the steering wheel 3 is further steered, and the front cylinder 7
When the volume of the left chamber 7c decreases, the oil discharged at this time flows into the left chamber 15c of the I/i-th rear cylinder 15, and the piston 15 installed in the No.
t) to the right in the figure. Therefore, as shown in Figure S, as the steering angle increases, the rear wheel turning angle decreases, the understeering characteristic that occurs in front-wheel drive vehicles is canceled out, the limit characteristics during cornering are improved, and driving stability is improved. Can be rotated. In a rear-wheel drive vehicle or a T-wheel drive vehicle in which driving force is applied by the rear wheels, when the controller 23 determines that the lateral acceleration applied to the vehicle is equal to or higher than the set acceleration, the steering angle adjustment device 20.20' The pistons 20b, 20b/ are moved inward by actuators 20d, 20d', respectively, and operate to further increase the biasing force of the springs 20c, 20c'. In this state, the steering wheel 3 is further operated, and the left chamber 7 of the front cylinder T
When the volume of the rear cylinder c decreases, the oil discharged at this time flows into the left chamber 14c of the steering wheel cylinder 14 without being absorbed by the steering angle adjusting device 20, and the oil is discharged into the first rear cylinder 14.
The piston 14b installed inside is moved to the right in the figure.

Therefore, as shown in Fig. 6, as the steering angle increases, the rear wheel steering angle increases with a larger steering ratio, and the oversteering characteristic that occurs in rear-wheel drive vehicles is canceled out. This improves driving stability and makes it possible to turn with better driving stability.

Next, a second embodiment of the present invention will be described. FIG. 2 is a schematic explanatory diagram illustrating the second embodiment. Left and right front wheels IL11R
As in the first embodiment, the steering device #12 that steers the steering wheel 3 includes a power steering device 4 that converts the rotational motion of the steering wheel 3 into a linear motion, and a power steering device [4]. A tie rod 5.5' that is connected to the end of the rack 4a that moves due to actuation, and a knuckle arm 6.6 that has one end connected to the end of the tie rod 5.5' and the other end connected to the front wheels IL, 1R.
’. power steering system f4
Vi Hower cylinder 4b is provided, and when oil flows into this power cylinder 4b in accordance with the operation of the steering wheel 3, the front wheel IL is heated.

It is designed to be steered to 1R. Rear wheel 8 a %8
b is steered by an oil-operated rear wheel steering device 33, but this rear wheel steering device @33 is a cylindrical cylinder case 33.
a, a connecting member 12 disposed within the cylinder case 33a and movable in the width direction of the vehicle body, and a cylindrical cylinder case 33a attached approximately to the center of the connecting member 12 to the left chamber 33c and the right chamber 336. a piston 33e that is separated into two parts, and a tie rod 10, one end of which is pivotally connected to the end of the connecting member 12.
10' and this tie rod 10.The end of 10' and the rear wheel 9
a knuckle arm 8 that connects the rear wheels 9L and 9R and converts the movement m of the connecting member 12 in the vehicle width direction into rotational movement of the rear wheels 9L and 9R;
．． It consists of 8'. A left chamber 33c and a right chamber 33d of the rear wheel steering device 33 are provided with return springs 33f and 33f symmetrically, respectively.
33f has been reduced. These return springs 3
3f.

One end of 33f' is in contact with each inner end surface of cylinder case 33a, and the other end is in contact with suppression 6 provided on each connecting member 12.
33g and 33g'.

These suppressing plates sag and 33g' can be engaged with annular engagement pieces 33h and 33h' that are integrally provided on the connecting portion @12, and are also engageable with strut j pieces 331 and 331' that are integrally provided on the cylinder case 33aK. The connecting member 12, that is, the piston 33e is held in a neutral position with a set load by the return spring 33e.

The /4' power steering device 4 for steering the front wheels and the rear wheel steering device 33 are operated by dividing oil supplied to a single oil pump 30 by a flow dividing device 32. This flow dividing device 32 is a controller 35
By controlling this, the oil supplied to the rear wheel steering device 33 side can be adjusted. Further, a flow path switching device 34 is interposed between the flow dividing device 32 and the left chamber 33c and right chamber 33d of the rear wheel steering device 33.

This flow path switching device 34 is connected to a vehicle speed signal detected by a vehicle speed sensor 21 and an oil pressure sensor 2 that detects a cylinder oil pressure of a power cylinder 4b of a power steering device 4.
It is controlled by the controller 35 which inputs 2, and selects one of the left chamber 33C and right chamber 33d to which oil is supplied.

The controller 35 first determines whether the lateral acceleration received by the 'Ri Cup is equal to or higher than the set acceleration based on the vehicle speed detected by the vehicle speed sensor 21 and the cylinder oil pressure detected by the oil pressure sensor 22, based on the above-mentioned formula, and sets the value. If the acceleration is less than that, the rear wheel steering angle is increased based on the cylinder oil pressure corresponding to the front wheel steering angle. At low speeds, the rear wheel steering angle is increased in the opposite phase as the front wheel steering angle increases; at high speeds, the front wheel steering angle is increased. The flow switching device f is increased in the same phase according to
At t11 L, the oil from the oil pump 30 is supplied to the left chamber 33c or the right chamber 33d. Therefore, it is possible to reduce the turning radius at low speeds, and to change lanes smoothly and with good maneuverability at high speeds.

When the controller 35 determines that the lateral acceleration received by the vehicle is greater than or equal to the set lateral acceleration while driving at high speed, that is, when the front wheels and rear wheels are being steered in the same phase, the rear wheel steering angle is If the vehicle is a front-wheel drive vehicle or a rear-wheel drive vehicle where the driving force is applied by the front wheels, the rear-wheel drive vehicle has a steering ratio smaller than the steering ratio when the lateral acceleration received by the vehicle is less than the set lateral acceleration. Alternatively, in a Q-wheel drive vehicle in which the driving force is applied by the rear wheels, the flow dividing device 32 is configured to set a steering ratio larger than the steering ratio when the lateral acceleration received by the vehicle is less than the set lateral acceleration. Controlled by controller 35
Over the course of 1ζ, the ratio of the amount of oil supplied to the power cylinder 4b of the worst steering device 4 and the amount of oil supplied to the left chamber 33c or right chamber 33d of the rear wheel steering device 33 is changed. Therefore, in a front-wheel drive vehicle or a single-wheel-drive vehicle in which driving force is applied by the front wheels, the understeering characteristic is eliminated; In this case, the oversteering characteristic is eliminated.

In addition, in each of the above embodiments, only oversteer 1)
Rather than creating a vehicle with neutral steering characteristics such as steering characteristics or understeering characteristics, the above-mentioned 1. As mentioned above, it is possible to change a vehicle with understeering characteristics to one with oversteering characteristics to give it a sporty feel, or conversely, to change a vehicle with oversteering characteristics to a vehicle with oversteering characteristics [2. It is also possible to use it as a vehicle.

Further, in each of the above embodiments, the vehicle speed is measured by a vehicle speed sensor, but as described above, the vehicle speed can be estimated by the front wheel steering angle corresponding to the vehicle speed, that is, by the oil pressure sensor.

(Effects of the Invention) The present invention enables the vehicle body to receive an acceleration of 4Ii/l based on the vehicle speed detected by the vehicle speed sensor and the cylinder oil pressure detected by the oil pressure sensor, without using an acceleration sensor.
When it is determined that the steering wheel is substantially in position when the lateral acceleration is less than the set lateral acceleration, the steering angle of the rear wheels, that is, the steering ratio, which is determined according to the vehicle speed or the steering angle of the front wheels corresponding to the vehicle speed, is changed. As a result, the steering ratio is changed without the response delay that occurs when an acceleration sensor is used, and understeering characteristics or oversteering characteristics are eliminated, resulting in extremely high limit characteristics during cornering. It is possible to obtain extremely good handling characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first embodiment of a Q-wheel steering system for a vehicle according to the present invention, FIG. 2 is a schematic diagram showing a fourth embodiment of the present invention, and FIG. 3 is a diagram showing a non-drive tire and a drive tire. The second figure is a graph showing a change in sideslip angle with respect to lateral acceleration, and the second figure is a graph showing an example of a characteristic showing the relationship between the steering angle and the steering characteristic of the conventional structure and the present invention. IL, IR...Front wheel 2...Sudare cylinder device T...Front cylinder! IL, 9
R...Rear wheel 14...First rear cylinder 15...No. 1 rear cylinder 16.16'...In-phase and opposite-phase switching device 20.20
'... Rudder angle adjustment device 21... Vehicle speed sensor 22... Oil pressure sensor 23.35...
・Controller 30... Oil pump 32... Diversion device 33... Rear wheel steering device 34... Flow path switching device Fig. 4 aML G @ 5 Figure Spur υReso Marty'll-e+ Figure 6 Stair Link "Voice, t 61-+

Claims (1)

[Claims] A power steering device that steers a front wheel; a rear wheel steering device that steers the rear wheels in the same phase direction at a predetermined steering ratio according to a steering angle of the front wheels steered by the power steering device; A hydraulic pressure sensor for detecting the cylinder hydraulic pressure of the steering device, and at least a correction means for changing the steering ratio when the lateral acceleration obtained from the cylinder hydraulic pressure detected by the hydraulic pressure sensor is equal to or higher than the set lateral acceleration. J-wheel steering system for vehicles.