JPH0216941Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a vehicle steering device, and more particularly to a vehicle steering device that performs auxiliary steering control of rear wheels in accordance with the steering angle of a steering wheel.

(Prior art) In order to improve vehicle maneuverability and stability, the rear wheels are generally steered in the same direction as the front wheels, so-called understeer, when the vehicle is operating the steering wheel at a small steering angle when the vehicle is running at high speed, and when the vehicle is running at low speed. A device has been proposed that steers the rear wheels in a direction opposite to the front wheels, so-called oversteer, when the steering wheel is operated at a large steering angle. However, mechanical steering devices that use link mechanisms have problems such as a low degree of freedom in layout due to the relationship with the rear wheel suspension, and limitations such as being limited to specific types of vehicles. Furthermore, a drawback of this link mechanism is that the steering angle of the steered wheels and the turning angle of the rear wheels, that is, the amplitude of the steering movement of the rear wheels, are in a sinusoidal relationship. The steering angle was symmetrical with respect to the rear wheel neutral position. Therefore, it is possible to appropriately select the amplitude of the steering angle of the rear wheels in the steering direction corresponding to the steering angle and direction of the steered wheels, and to make the steering characteristics different between the under side and over side. There is a drawback that it is lacking.

(Purpose) In view of the above-mentioned problems or shortcomings, the present invention provides a device for steering the rear wheels according to the steering angle of the steering wheel, specifically, a device for steering the rear wheels according to the steering angle of the steering wheel. To provide a steering device for a vehicle capable of steering the front wheels in the front wheel steering direction, and steering the rear wheels in the opposite direction to the front wheel steering direction when the steering angle becomes large.

(Structure) In order to achieve this object, the vehicle steering device of the present invention steers the front wheels by steering operation of a steering wheel, and also steers the rear wheels according to the steering operation of the steering wheel. A hydraulic supply source for supplying pressure oil, a hydraulic actuation means for steering the rear wheels, a hydraulic pipe for guiding the pressure oil to the hydraulic actuation means, and a hydraulic pipe provided in the hydraulic pipe for supplying the pressure oil to the hydraulic actuation means. A switching valve that switches the flow, a steering angle detection means that detects the steering angle of the steering wheel, and a switching valve that switches the switching valve according to an output signal corresponding to the steering angle of the steering wheel from the steering angle detection means, and also supplies a hydraulic pressure supply source. It is characterized by comprising a control means for changing the flow characteristics of the pressure oil.

(Example) The vehicle steering system of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic plan view of a vehicle equipped with a rack and pinion type steering device and a semi-trailing arm type suspension on the rear wheels.

In the figure, 1 is the vehicle body, 2 is the front wheel, 3 is the knuckle arm, 4 is the side rod, 5 is the rack gear, 7 is the pinion gear, 8 is the variable throttle valve whose oil amount changes according to the steering force, 9 is the handle, and 10 is pressure oil. A hydraulic pump is used as a supply source, 11 is a reservoir tank for hydraulic oil, and 12a and 12b are hydraulic pipes. Further, 13 is a rear wheel, 14 is a rear wheel suspension member, and 15 is a differential gear housing. The member 14 and the housing 15 are fixed with bolts so that they move together. 16 is an insulator rubber of the rear wheel suspension member 14;
4 is the pin 17 via the insulator rubber 16
It is elastically fixed to the vehicle body 1 by. 18 is a differential gear insulator, and the differential gear housing 15 is elastically fixed to the vehicle body 1 by a pin 19 via the insulator 18. 20 is a semi-trailing arm,
21 is a drive shaft. 22 is a steering angle detection means for detecting the steering angle of a steering wheel, that is, a steering wheel; 23 is an electromagnetic switching valve that switches the flow of pressure oil in response to an output signal from the steering angle detection means. A,
Reference numeral B denotes a hydraulic cylinder device as an example of hydraulic actuating means, which is installed between the suspension member 14 and the vehicle body 1 so as to rotate the rear wheel suspension member 14 around the fixing pin 19 of the differential gear insulator 18. Arrange. In addition, each hydraulic cylinder 24 and the vehicle body 1, and each hydraulic piston 25 and the suspension member 14 are each connected with a pin. 26 is the steering angle detection means 2
It is a control means for switching the switching valve 23 according to the output signal from the switching valve 23. The hydraulic pump 10 and the cylinder devices A and B are connected to the hydraulic pipe 1 via the electromagnetic switching valve 23.
Connected by 2a and 12b.

Next, the operation of the first embodiment shown in FIG. 1 will be explained using FIGS. 2 and 3. In the figure, the same reference numerals as in FIG. 1 indicate equivalent parts.

Now, when you turn the steering wheel 9 to the left while driving (in the case of a small steering angle), the variable orifices 8a, 8 of the variable throttle valve 8
b is throttled and the variable orifices 8c and 8d are opened, so that high-pressure fluid flows into the oil chambers e and f of the hydraulic cylinders A and B through the hydraulic pipe 12a. On the other hand, low-pressure fluid flows through the hydraulic pipe 12b into the oil chambers g and h, which are opposite to the oil chambers e and f, respectively, so that the hydraulic pressure is adjusted according to the pressure difference between the pressure oils acting on both the oil chambers e, g and f, h. Cylinders A and B operate to deform the insulator rubber 16 as shown in FIG. As a result, the rear wheels 13 tend to be steered to the left, that is, to understeer. At this time, the pump 10 is controlled by the control means 2 so that its discharge amount gradually decreases as the steering angle increases and approaches a certain constant value _α0 , as shown in FIG. 6a, as shown in FIG.
6. When the steering angle reaches a constant value _α0 , the discharge amount of the pump 10 becomes almost zero, so the pressure difference acting on the oil chamber becomes small, the hydraulic cylinder assumes an equilibrium position, and the rotation of the rear wheels relative to the steering angle of the handlebar 9 becomes smaller. As the rudder angle becomes zero, Fig. 6b
As shown in , the switching valve position changes from (left side position in the figure) to (right side position in the figure).

Further, the control means 26 controls the discharge amount of the pump 10 to gradually increase in accordance with the steering angle when the steering angle becomes larger than a constant value α ₀ . Therefore, when the steering angle is around α ₀ , even if the steering wheel 9 is turned slightly left or right, the rear wheels 1
3 is substantially in equilibrium with the vehicle body 1. When the steering wheel 9 is further turned to the left as shown in FIG. 3, the control means 26 sets the electromagnetic switching valve 23 to the position shown in the figure based on the output signal from the steering angle detection means 22. As a result, each oil chamber g, h of hydraulic cylinders A and B
High-pressure fluid acts on the oil chambers e and f, and low-pressure fluid acts on the oil chambers e and f, steering the rear wheels 13 in the opposite direction to that shown in FIG. 2, that is, toward the oversteer side. In this case, the amount of oil supplied to the variable throttle valve 8 by the pump 10 is as shown in Figure 6a.
As shown in the figure, when the steering wheel steering angle is larger than α ₀ , it is increased more than when it is smaller than α ₀ , so when the throttle opening of the variable throttle valve 8, which is determined correspondingly with respect to the steering wheel steering force, is a predetermined opening, As shown in Figure 6c, the steering angle of the rear wheels relative to the steering angle of the steering wheel can be made larger when the front wheels are in the opposite direction than when the front wheels are in the same direction. As shown in the figure, the steering angle of the rear wheels 13 does not become sinusoidal, and the degree of freedom in design is increased. In addition, the variable throttle valve 8 is adjusted according to the steering force of the steering wheel.
Since the opening degree of the throttle changes, the steering angle of the rear wheels shown in FIG. 6c can be modified using the steering force of the steering wheel as a parameter.

FIG. 4 shows another embodiment of the invention. 1st to 3rd
The same reference numerals as in the figure indicate equivalent items. In this embodiment, instead of the hydraulic cylinder device and the insulator rubber 16, an insulator rubber 27 having hollow oil chambers 27a and 7b in the rubber part is provided at the installation position of the insulator rubber 16, and the hydraulic pipe 12a , 12b are directly connected to each oil chamber of the insulator rubber 27. The operation of this embodiment is similar to that of the first embodiment, so the explanation will be omitted.

FIG. 5 shows a third embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 indicate equivalent parts. In this embodiment, a control valve 28 is interposed between the hydraulic pump 10 and the variable throttle valve 8, so that the amount of pressure oil discharged from the pump 10 can be increased or decreased. In other words, the steering angle at which the amount of pressure oil discharged from the pump 10 is almost zero is set as α ₀ in the first embodiment, but it can be set variously by adjusting the control valve 28, so the degree of freedom in setting is becomes larger.

(Effects of the invention) As described above, according to the invention, the rear wheels are steered using hydraulic actuation means according to the steering angle of the steering wheel, so compared to a mechanical steering device using a link mechanism, The relationship between the steering angle of the steering wheel and the turning angle of the rear wheels can be freely changed.
In addition, since all that is required is pressure oil piping, it is not limited to a specific vehicle and has a wide range of applications. Furthermore, it is also possible to adjust the steering characteristics of the rear wheels. Also,
In each of the above-mentioned embodiments, a variable throttle valve is provided in the middle of the hydraulic pipe to change the flow characteristics according to the steering force of the steering wheel. It is possible to obtain stable cornering characteristics intended by the driver.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a vehicle equipped with the device of the present invention;
2 and 3 are schematic plan views showing the operation of the device of the present invention;
FIG. 4 is a schematic plan view of another embodiment of the device of the present invention, and FIG. 5 is a schematic plan view of another embodiment of the device of the present invention.
FIG. 6 is a diagram showing the control characteristics of the device of the present invention. 1...Vehicle body, 2...Front wheel, 3...Knuckle arm, 4...Side rod, 5...Rack gear, 7
...Pinion gear, 8...Variable throttle valve, 9...Handle, 10...Hydraulic pump, 11...Reservoir tank, 12a, 12b...Hydraulic pipe, 13...
...Rear wheel, 14...Rear wheel suspension member,
15...Differential gear housing, 1
6, 27... Insulator rubber, 17, 19
... Pin, 18 ... Differential gear insulator, 20 ... Semi-trailing arm, 2
DESCRIPTION OF SYMBOLS 1... Drive shaft, 22... Rudder angle detection means, 23... Solenoid switching valve, 24... Hydraulic cylinder, 25... Hydraulic piston, 26... Control means,
27a, 27b... oil chamber, 28... control valve.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A hydraulic supply source that supplies pressurized oil in a vehicle steering device that steers the front wheels by steering the steering wheel and also steers the rear wheels in response to the steering operation of the steering wheel. a hydraulic actuating means for steering the rear wheels; a hydraulic pipe for guiding pressure oil to the hydraulic actuating means; a switching valve provided in the hydraulic pipe for switching the flow of pressurized oil to the hydraulic actuating means; and the handle. a steering angle detection means for detecting a steering angle of the steering wheel; and an output signal from the steering angle detection means corresponding to the steering angle of the steering wheel, the switching valve is switched, and the flow rate characteristics of the pressure oil supplied from the hydraulic pressure supply source are controlled. A steering device for a vehicle, characterized in that it comprises a control means for changing. 2. The vehicle steering system according to claim 1, wherein the hydraulic pipe has a variable throttle valve located in the middle thereof, which changes the flow rate characteristics according to the steering force of the steering wheel. 3. The vehicle steering system according to claim 1 or 2, wherein the control means includes a control valve that controls the amount of pressure oil supplied from the hydraulic pressure supply source.