JPS5977968A - Four-wheel steering gear for vehicle - Google Patents

Abstract

PURPOSE:To enhance operability of a four-wheel steering gear at intermediate and high vehicle velocities, by providing a controller for controlling a rear-wheel steering gear in accordance with rear-wheel steering angle characteristics relative to a front-wheel steering angle. CONSTITUTION:Front wheels 1, 1 and rear wheels 2, 2 are mechanically separated from each other, an output 4a from a front-wheel steering angle sensor 4 detecting a steering angle thetaH of a steering wheel 3 is inputted into a controller 10 for the rear-wheel steering gear, and the rear wheels 2, 2 are steered by the input signal. A point of inflection P1, P2... at which a steering ratio thetaR/thetaF is reduced is varied toward a smaller front-wheel steering angle thetaF as the vehicle velosity is increased, so that a G range is reduced with an increase is the vehicle velocity, and the rear-wheel steering angle thetaR reaches a limit value theta'R for a small front-wheel steering angle thetaF, thereby enhancing operability. In addition, a higher steering ratio is obtained for a higher vehicle velosity, whereby response characteristic at the time of a lane change at an intermediate or high vehicle velocity is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for steering both the front wheels and the rear wheels of a four-wheel vehicle such as an automobile, that is, a four-wheel steering system that steers the rear wheels as well as the front wheels by steering the front wheels, which are steering wheels. It is related to the device.

Conventionally, the steering system for four-wheeled vehicles steers only the front wheels, and the rear wheels are actively steered, although they may exhibit some toe-in or 1~--1--altitude 1-- depending on the driving situation, regardless of the steering of the front wheels. It is not designed to steer. Recently, however, a four-wheel steering system has been proposed in which both the front wheels and the rear wheels are steered (for example, Japanese Patent Application Laid-Open No. 55-91458), and research on this type of system is underway.

If the four-wheel steering system is used, it becomes possible to perform convenient maneuvers that were previously impossible, and to drive with improved steering performance, depending on the various driving conditions of the vehicle. For example, when maneuvering a vehicle that moves at an extremely low speed d'-3 (), such as in tandem and 1-car or parking in a garage, by steering the rear wheels in the opposite direction to the front wheels (
(This is called reverse phase), it becomes possible to greatly change the direction of the vehicle, and it becomes possible or easier to park in narrow spaces, which was previously impossible or extremely difficult.

Further, in a U-turn, the minimum turning radius can be made small, which is advantageous. Furthermore, by steering the rear wheels in a phase opposite to that of the front wheels, the difference between the inner wheels can be minimized or eliminated, which is advantageous when turning a narrow corner. In addition, when steering a vehicle at extremely low speeds, if the rear wheels are steered in the same direction as the front wheels (this is called in-phase), it becomes possible to move the entire vehicle in parallel, making it easier to park or park the vehicle. It is often convenient when putting it in.

On the other hand, when changing lanes while driving at medium to high speeds,
If four-wheel steering is performed in the same phase, a lateral force will be applied to the front and rear wheels, making it possible to perform a smooth lane change without phase delay, and this will not cause yawing, allowing for lane changes at high speeds. can be done without fear. Furthermore, during twenty-one navigating, the direction of the vehicle can be effectively changed by steering the rear wheels in opposite phases.

Roughly speaking, when driving straight ahead, if the rear wheels are steered in a direction that counteracts the effect of external disturbances such as crosswinds, stable driving can be maintained against external disturbances, and stable driving can be achieved. It is also possible to improve the high-speed straight running performance by 1.

Additionally, even if the vehicle accelerates or decelerates while keeping the steering angle of the front wheels constant during a turn, the steering angle of the rear wheels changes in accordance with the acceleration or deceleration, thereby ensuring that the vehicle does not deviate from its course and making stable turns. It can also be written as

In other words, in conventional vehicles, the steering characteristics are adjusted to have a slight tendency to understeer in order to maintain straight-line stability, and when accelerating during a turn, there is a tendency for the vehicle to deviate outward from the course. By rotating the helm, the deviation can be corrected and a stable turn can be made.

From the standpoint of comfort, it is possible to obtain a small minimum turning radius with the same wheelbase, so the wheelbase can be made thicker, and in this case, the actual steering angle of the front wheels can be made smaller. It has many advantages, such as the ability to make new designs possible.

As described above, four-wheel steering has 41 practical advantages and is extremely useful.

Regarding this four-wheel steering, various specific configurations have been proposed so far to effectively steer the rear wheels. For example, four-wheel steering is performed in opposite phases at low speeds and in the same phase at high speeds (Japanese Unexamined Patent Publication No. 55-91457), and when the steering angle of the front wheels is small, it is in the same phase, and when it is large, it is in opposite phases. (Japanese Patent Publication No. 5'6-5270), the rear wheels are steered in proportion to the steering angle of the front wheels only when the steering angle of the front wheels is below a predetermined range, and when the steering angle of the front wheels is above a predetermined range, the front wheels are steered in proportion to the steering angle of the front wheels. A device in which the steering angle of the rear wheels is constant regardless of the steering angle (Japanese Patent Application Laid-Open No. 1986-
No. 163969), etc. are known.

These four-wheel steering devices often require a large change in the direction of the vehicle when the vehicle speed is low or the front wheel steering angle is large, but only slightly when the vehicle speed is high or the front wheel steering angle is small. The system is designed to always steer the rear wheels in the desired direction based on the empirical rule that there are many cases where a sideways shift is desired.

However, in actual driving of a vehicle, sufficient maneuverability and driving stability cannot be obtained simply by considering the vehicle speed and the front wheel steering angle independently.

For example, when turning with a constant front wheel steering angle,
Even if the rear wheels are steered with a desirable steering ratio corresponding to this steering angle, acceleration or deceleration during a turn may cause the vehicle to deviate from or inward from the course.

This is because the centrifugal force (lateral force) changes as the vehicle speed changes, but in order to keep the vehicle from going off course, the front wheels should be It is necessary to change the steering ratio of the rear wheels.

Therefore, the rear wheel steering angle (steering ratio) relative to the front wheel steering angle
is desirably changed depending on the vehicle speed. In addition, in the medium-high speed range, when the vehicle speed is high, the steering ratio is increased in the same phase, and the lateral acceleration (G) is increased to enable smooth lane changes to improve maneuverability. It is desirable to reduce the steering ratio and reduce the lateral acceleration as the vehicle speed decreases from low to medium speed.

Furthermore, there is a region where the rear wheels are steered in response to front wheel steering (a region where lateral acceleration G is less likely to occur and is called the G region).
It is desirable that the value decreases as the vehicle speeds up, and increases as the vehicle speed decreases. In other words, as the speed increases, it is desirable to increase the steering ratio and turn the rear wheels to a large extent with a small amount of steering to improve responsiveness and maneuverability.

SUMMARY OF THE INVENTION In response to the above-mentioned demands, it is an object of the present invention to provide a four-wheel steering system with improved maneuverability at medium and high speeds.

The four-wheel steering device according to the present invention comprises a steering device that steers the front wheels, a rear wheel steering device that steers the rear wheels, and a controller that controls the rear wheel steering device according to the steering angle of the front wheels. In the steering system, when the front wheel steering angle is below a set value, the rear wheel steering angle is increased in accordance with the increase in the front wheel steering angle, and when the front wheel steering angle is above the set value, the rate of increase is reduced. The present invention is characterized in that control is performed having an inflection point, and the inflection point is controlled to change to the side where the steering angle of the front wheels is small in accordance with an increase in vehicle speed.

In other words, an inflection point is provided in the rear wheel steering angle characteristics relative to the front wheel steering angle, and this inflection point is changed to the side where the front wheel steering angle is smaller as the vehicle speed increases, thereby making the G region smaller. It is characterized by the following.

According to the four-wheel steering system of the present invention, in a small range where the front wheel steering angle is less than the setting property, the rear wheel steering angle increases in accordance with the increase in the front wheel steering angle. In a range where the front wheel steering angle is large beyond this set value, the rate of increase decreases, resulting in a yaw range where yawing is more likely to occur, and changes in the front wheel steering angle, that is, the steering angle. In addition, as the vehicle speed increases, the inflection point changes to the smaller front wheel steering angle, so the G area becomes smaller ε, making it easier to change lanes when changing lanes. This improves the responsiveness of the vehicle and improves handling stability.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figures 1, 2, and 3 show the rear wheel steering angle (0 shaku) relative to the front wheel steering angle (θF) in the four-wheel steering system of the present invention.
Examples of the characteristics are shown. The characteristic curve for the highest speed Vl has an inflection point P1 at a place where the front wheel steering angle θF is small, and the characteristic curve for a vehicle speed V2 lower than the medium speed V1 has an inflection point. P2 is at a comparatively large front wheel steering angle θF, and in the characteristic curve at a lower vehicle speed v3, the inflection point P3 is at the largest point of the front wheel steering angle θF1. A characteristic curve of v4 is shown, and in this characteristic curve, after passing the inflection point P4 and Ic, as the front wheel steering angle θF increases, the rear wheel steering angle 0 changes from positive to negative, and the phase becomes opposite. It shows.

In the example shown in Fig. 1, once the rear wheel steering angle θR reaches a predetermined value θR', it will not increase any further; The rear wheel steering angle 0 shaku also increases in proportion to the increase in θF. However, the steering angle (θR/θF) increases as the medium speed increases, and when θR is small, θR reaches θR', and the G region (
The area where 0 scale increases as θF increases) is small. When the vehicle speed decreases, the steering ratio (θR/θF) decreases, and therefore the G region increases.

Example C in Fig. 2 is more popular when the predetermined value (limit value) θR' of θR is high speed, and as in Fig. 1, the inflection point 1) changes toward the larger high-speed culm θF. It has become. This is because it is often necessary to change the direction of the vehicle at low speeds, so a limit is set for the rear wheel turning angle θR to be as small as possible at low speeds to prevent the vehicle from skidding η when changing direction. That's what I do.

In Figure 3, after reaching the inflection point P, the steering ratio is made negative and (
When the front wheel steering angle θF is large (except at the highest speed), the phase tends to be opposite, and at low speeds, the front wheel steering angle θF is set to the predetermined front wheel steering angle θF.
′, the phase is reversed.

According to each of these embodiments of the present invention, the steering ratio θR/θF
The inflection points p1, p2, etc., where the front wheel steering angle θF becomes smaller as the vehicle speed increases, the G area becomes smaller as the vehicle speed increases, and the front wheel steering angle θF becomes smaller. At the wheel steering angle θF, the rear wheel steering angle θR reaches the limit value θR', making it possible to improve maneuverability, and the higher the vehicle speed, the larger the steering ratio θR/θF, which makes it possible to achieve medium-high speed (
It is possible to improve responsiveness when changing lanes.

Next, referring to M4 diagram J3 and FIG. 5, a specific configuration of a four-wheel steering system that realizes the characteristics as in the above embodiment will be explained. FIG. 4 shows an example using hydraulic pressure, and FIG. 5 shows an example using links. .

In the configuration shown in FIG. 4, the front wheels 1, 1 and the rear wheels 2, 2 are mechanically separated, and the output (la) of the front wheel steering angle sensor 4 which detects the steering angle θH of the steering wheel 3 is used for rear wheel steering. equipment]
This input signal is input to the roller 10, and the rear wheels 2, 2 are steered by this input signal.The front wheel steering device is
As is well known, a rack 6 is moved in the width direction of the vehicle (indicated by arrow A) by a pinion 5 fixed to a steering shaft 3A to which a steering wheel 3 is fixed, and tie rods 7. 7 to the right front wheel 1, knuckle arm 8, 8 to its shaft 8a.
.

J that rotates around 8a and steers the front wheels 1, 1 left and right.
It is composed of That is, when the steering wheel 3 in the figure is rotated in the direction of the arrow, the steering shaft 3A is rotated in the direction of the arrow, the binion 5 is also rotated to the right, and the rack 6 is moved in one direction. As a result, the knuckle arms 8, 8 of the left and right front wheels 1.1 are rotated in the right direction via the links 7, 7, and the front wheels 1.1 are rotated in one direction around the axes 8a, 8a of the knuckle arms 8, 8. Rotate and steer to the left.

At this time, the steering angle sensor 4 outputs a signal /Ia indicating that the steering wheel 3 has rotated in one direction by an angle θH.
and outputs this as controller 1 to roller 1 of the rear wheel steering device.
0 front wheel turning angle input 10A.

] to [1-ra 10 is supplied with electric power by the power source 11, and in addition to the front wheel steering angle input 10A, the vehicle speed sensor 1
2 connected to the vehicle speed human power 10B and the rear wheel steering angle sensor 1
A steering direction output 101) connected to a solenoid l' 20 that roughly controls the steering direction of the rear wheels, and a hydraulic pressure controller that controls the steering angle θR of the rear wheels. A hydraulic pump motor output 10E connected to the motor 21A of the main pump 21 is provided.

The hydraulic main pump 21 includes a pump 21B that discharges oil (hydraulic oil), and this pump 21B is connected to a C hydraulic actuator 23 via a steering direction switching valve 22, and between this valve 22 and the pump 21B. In this case, short-circuit the oil outgoing path 24Δ and the oil return path 24C, and
An orifice path 2413 with a refit (24I) is installed (
An oil reservoir 25 is arranged in the middle of the A-il return path 24C.

The steering direction switching valve 22 has two inlets connected to an oil outgoing path 24△ and an oil outgoing path 24G, and two inlets communicating therewith.
The valve part consisting of two outlets, forward 22A, reverse 22B,
Three stop valves 22C are switchably provided in parallel, and by operating the solenoid 20, these three valve parts 2
Either one of 2A and 22f3.22G is the oil company road 2/IA.

It is connected to long route 24C. The two outlets of this valve 22 are respectively connected to a right oil passage 23R and a left oil passage 23L of a hydraulic actuator 23, and these right oil passage 23R and left oil passage 231- are connected to each other through this valve 22. The outward route 24Δ and the far route 24C (two are connected to each other).

Hydraulic actico”--923 is the right and left oil passage 23
Due to the pressure difference applied to R123L, the rod 26, which is its output shaft, is moved in the width direction of the vehicle (indicated by arrow B),
The knuckle arms 28, 28 of the rear wheels 2, 2 are rotated around their shafts 28a, 28a via the tie [J Rad 2 f, 27, thereby steering the rear wheels 2, 2 left and right.

In the illustrated example, the front wheels 1, 1 are steered to the left,
When steering the rear wheels 2, 2 in the same phase as the front wheels 1, 1, the steering direction switching valve 22 is set to the positive 22Δ position, and the oil is passed from the outward path 24A through the orifice path 2/+13. It flows into Route 59 24C, passes through Lizano\25, and returns to pump 21B. As a result, the pressure on the forward path 24A side (just before the orifice 2/1+1 becomes high), and the pressure behind the orifice 24b, that is, on the iE path 2/IC side, becomes low, and the pressure on the positive 22°A portion of the valve 22 pressure in the right oil passage 23R through the side oil passage 231.
The pressure becomes higher than that of -, and the actuating rod 26 of the actuator 23 is driven in the opposite direction. The driving force for this cutting is determined by the current force input to the main pump motor 21A. As a result, the rear wheels 2.2 are steered to the left via the tie rods 27.
2 is steered in the same phase as the front wheels 1.1.

Steer front wheels 1.1 to the right, and turn rear wheels 2, 2 to 1°1.
When steering in the same phase as
2 to the reverse 22B position, and open the right oil passage 23R.
The pressure relationship between the oil passage 231 and the left oil passage 231- is reversed to that described above, and the actuating rod 26 is driven rightward.

In addition, if the rear wheels 2, 2 are steered in the opposite phase to the front wheels 1, 1), the correspondence between the forward direction 22A1 and the reverse 22B of the steering direction and steering direction switching knob 22 is set to the same phase σ, as in the case). On the contrary, the front wheels 1 and 1 are turned to the left (if this is the case, the front wheels 1 and 1 are turned to the reverse 22B, and the front wheels 1 and 1 are turned to the right) (if this is to be turned, the front wheels 1 and 1 are turned to the right 22A). .

When setting the steering angle θR of the rear wheels 2, 2 to zero, 41. /＼ Connect the stop 22G part of the lubricant 22 to the aisle passage to cut off the communication between the pump 21C and the hydraulic actuator 23,
Left and right A-il passages 23L, 2 of the hydraulic actuator 23
Set the pressure difference between 3R to 41<C, and set the f1 moving rod 26 to the neutral position. At this time, make sure that the actuating rod 1-26 is set in the neutral position. It is desirable that te a3 <.

The steering direction of the front wheels 1.1 is input to the controller 10 by the output curve 1a of the front wheel steering angle sensor 4, and is inputted to the controller 10: J:
1. : Whether to set the rear wheels 2, 2 to be in the same phase or opposite phase to the front wheels 1.1 is determined according to the width j* detected by the vehicle speed sensor 12 and according to a preset vehicle speed corresponding pattern] (~Roller 10 is determined.

=1-1~[1-ra10 is the input θH from the steering angle sensor 4 (this is proportional to the steering angle θF of the front wheels 1, 1),
In response to the input V from the medium speed range 12, outputs a control signal according to the characteristics shown in FIGS. 1 to 3,
A four-wheel steering system using an AL+ pressure actuator as described above, which steers the rear wheels 2 and 2, allows the rear wheels to be steered smoothly, but the steering is equipped with a special system for four-wheel steering. This is carried out without applying a 4-J load, which is advantageous in practice.

However, hydraulic systems require heavy and costly parts such as motors, pumps, hydraulic actuators, and valves for rolls, which increases the weight of the vehicle and complicates assembly during manufacturing. It is not suitable for relatively small 4-wheel vehicles because it becomes a cause of high prices.Therefore, a 4-wheel steering system using a simple link 1%l Ji,l is practically advantageous. In some cases.

An example of this type of link type mechanism will be explained below with reference to FIG. In addition, in the structure of FIG. 5, the same parts as those in the structure of FIG. 4 are given the same numbers, and their explanations are omitted.

In the link type configuration shown in FIG. 5, the part t of the rack 6 that is moved in the width direction of the vehicle by the steering wheel
The slots 1 to 6A for sliding engagement are provided (J, and a link is provided between the slot 6A and the throats 1 to 41A for sliding engagement provided on the steering rods/11 of the rear wheels 2 and 2. The rear wheels 2, 1 are connected according to the steering angle θF of the front wheels 1, 1.
2 is steered in a desired direction by a desirable turning angle θR.

This link mechanism has a viscous engagement slot on the front wheel side.
A first L-shaped lever 331 is pivotally supported on an identification shaft 31a with one end 31A slidably engaged with the right side, and one end 32A is rotatably connected to the other end 311B of this first L-shaped lever 31. the connecting lever 32, the other end 3 of this connecting lever 32
A swinging lever 33 with one end 33A connected to 2B and the other end 33B pivotally supported on a fixed shaft 33a, the one end 33A of this swinging lever 33 and the other end 3 of the intermediate lever 32.
A control lever 3/l has one end 34A rotatably connected to a connecting shaft with the control lever 3;
A rotary shaft 35A is mounted on the feed sleeve 36 which is screwed onto the feed sleeve 36 (b sleeve 35, this screw 1).
A motor 38 that avoids rotation of -i7, a connecting lever 39 with -☆i7i and 39 A pivoted on a shaft support 3/'I△ provided at an intermediate position between the controller 1 and the roll lever 34;
d5 and one end 4O to the other end 39B of the three connecting levers.
A is connected, and the other end 40B is connected to 1-? on the rear wheel side. To the dynamic engagement slot 1/1.1 A to the second 1-
It consists of a glyph-shaped lever/llO.

The controller 38 is connected to the controller 50 and is driven by the output of the controller 50.

This controller 50 is supplied with power from a power source 51, and the output horns of the medium speed controller 1) 52 are turned on. Also,
This screw [1] is located near the cut 37.
A potentiometer 53 is arranged to feed back the position of the feed sleeve 36 screwed onto the tips 1 to 37 to the input of the motor 38, so as to control the position of the feed sleeve 36.

According to the four-wheel steering device equipped with the link mechanism as described above, when the steering wheel 3 is rotated to the left (in the direction of the arrow), the pinion 5, the rack 6, the tyron door 7, and the knuckle lure 1, 8, 8 , the front wheels 1 and 1 all rotate or move in the direction indicated by the arrow, and at the same time the front wheels 1 and 1 are steered to the left, the first 1-shaped lever 31 is rotated in the 1 direction around the fixed shaft 31a. 1, the swinging lever 33 is rotated in the L direction around the fixed shaft 33a via the intermediate lever 32, and the control levers 3 are swung in the G direction around the sleeve 35; At the same time as the three connecting levers move in the direction, the second 1-shaped lever /'I
Rotate O in the L direction to adjust the steering rods for rear wheels 2 and 2/11
is moved in the 1-1 direction, thereby steering the rear wheels 2.2 to the left in the same phase.

The controller 50 drives the motor 38 to move the feed sleeve 36 downward (to the left of the vehicle) in the figure, and when the feed sleeve 36 reaches the position of one end 39A of the connecting lever 39, the controller 50 moves the feed sleeve 36 downward (to the left of the vehicle). Even if the I-har 334 swings around the rotation shaft 35A of the sleeve 35, the connection lever 3
9 does not move forward or backward (in the left/right direction in the figure), so the rear wheels 2,
2 is not steered.

When the sleeve 35 is moved further downward by the drive of the motor 38 and exceeds the position of one end 39Δ of the connecting lever 39, the receiver moves in the same direction as above (L direction).
-1- The swinging of the lever 34 causes the connecting lever 39 to move forward in the opposite direction. This is because the lever 34 swings around the pivot shaft 35△ of the push sleeve 35. Therefore, in this case, the
L-shaped lever 40 (turn in the direction of arrow 1
．． The steering rod 41 of the rear wheel 2.2 moves in the direction of the arrow R.
2 is steered to the right, and four-wheel steering in )y phase is performed.

By driving and controlling the motor 38 by the outputs of the controller 1 to the roller 50, the feed sleeve 36 is
The receiver moves the sleeve 35 through the
By changing the position of the axis of swing of the wheels 1 to 34, and as a result, changing the direction of movement of the connecting lever 39, the rear wheels 2, 2
It is possible to change the direction of steering. Furthermore, by controlling the distance of movement of the sleeve 35, the receiver can also change the magnitude of the steering angle θR of the rear wheels 2, 2 in the same phase and in the opposite phase.
The outputs of the controller 1 to the roller 0 make it possible to arbitrarily control the direction A3 and magnitude of steering of the rear wheels 2.2 in accordance with the steering of the front wheels 1.1.

Since the output from the vehicle speed sensor 52 is input to the controller 50, the rear wheels 2, 2 are steered according to the magnitude of the steering angle θF of the front wheels 1, 1 via the above-mentioned link.
It is possible to control the magnitude (including the direction) of the steering angle θR in accordance with the characteristics of the steering ratio described in each of the above embodiments.

In this way, even with the one-link type configuration shown in FIG. 5, it is possible to realize the rear wheel turning angle characteristics with respect to the front wheel turning angle as in the above-described embodiment. In particular, this link type mechanism has less weight than a hydraulic type, has a simple structure, is easy to assemble, and can be manufactured at a low cost of 1~, so it is suitable for small vehicles.

As described above in detail, the four-wheel steering system of the present invention increases the rear wheel steering angle in accordance with the increase in the front wheel steering angle when the front wheel steering angle is less than the set value (inflection point). Above the set value, the rate of increase is reduced, and the inflection point is changed to the smaller side of the front wheel ψ steering angle in accordance with the increase in vehicle speed, increasing the G area. This improves responsiveness when changing lanes, and enables practical four-wheel steering.

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of a characteristic curve showing the relationship between the front wheel steering angle and the rear wheel steering angle in the four-wheel steering system of the present invention, and FIGS. 2 and 3 are graphs showing similar characteristic curves. A graph showing the other side of the curve, FIG. 4 is a schematic diagram showing an example of the four-wheel steering device of the present invention using hydraulic pressure, and FIG. 5 is an example of the four-wheel steering device of the present invention using a link mechanism. FIG. 1...Front wheel 2...Rear wheel 3
... Steering wheel 4 ... Steering angle sensor layer
・Pinion 6...Ratch γ, 27...Tie [1 Tsud 8, 28...
Knuckle arm 1 (1, 50...]n i~roller
12,52...Vehicle speed sensor 20...Solenoid
21...Main pump 22...Rear wheel 1: Rudder force I/J valve 23...Oil L [actuator
25... Reservoir 26... Rear wheel steering angle rod 31... First U-shaped arm 32... Intermediate lever 33... Rocking lever 34... Control lever 34A... Shaft support part 35...Receiver 35 A...Rotation shaft 36...
Feed sleeve 37...Screw rond 38...
・Drive motor 39...Connection lever 4o...Second L-shaped lever 41...Rear wheel steering rod (voluntary) procedure Ne Oj Masho December 22, 1981 Director General of the Patent Office 1, Incident Indication Japanese Patent Application No. 57-188023 2, Name of the invention 4-wheel steering system for vehicles 3, Relationship with the case of the person making the amendment Patent applicant 4, Agent 7, Subject of the amendment ``Detailed description of the invention'' in the specification ”
Column 8, contents of amendment 1) Insert 1 in the same phase between "rear wheels" and "1 steering" in line 14 of page 6 of the specification. 2) Insert "1" in line 3 of page 9 of the specification "1 steering". Correct "rudder angle" to "steering ratio". 3> Correct “0 shaku” in line 4 of the same page to [θF]. 4) Correct "large" to "small" in line 11 of the same page. 5) In line 15 of the same page, ``The vehicle is...'' is corrected to ``The difference between θF and 0 shaku is increased, and the yaw ray] is increased.'' 6) Insert "slope of characteristic curve" between "1 steering ratio" and "wo" in line 16 of the same page. 7) Lines 17 and 18 of the same page: [Front wheel steering angle...make the trend," corrected to "The lower the vehicle speed, the larger the slope." 8) On page 14, line 18, "Aisle passage" is corrected to "Oil passage." 9) On page 21, line 3, ``large chrysanthemum'' is corrected to ``small''.

Claims (1)

[Scope of Claims] A steering device that steers the front wheels, a rear wheel steering device that steers the rear wheels, a vehicle speed sensor, and when the front wheel steering angle is less than a set value, the rear wheel steering angle is adjusted as the front wheel steering angle increases. increases, and has an inflection point that reduces the rate of increase above this set value, and also changes this inflection point to the smaller side of the steering angle of the front wheels as the vehicle speed increases. A four-wheel steering system for a vehicle, comprising a controller that controls a rear wheel steering system based on characteristics of a rear wheel steering angle relative to a front wheel steering angle.