JPH10287255A - Steering device for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excessive load from being applied to a linkage even when a wheel is at a maximum deflecting angle, in a steering device for an automobile connecting a plurality of shafts by the linkage to be synchronized and steered hydraulically. SOLUTION: A shaft such as leading to a maximum deflecting angle a little earlier than a wheel of the other shaft is provided, and a pilot circuit conduction device of mechanical valve or the like operated when a wheel of this shaft comes to be at the maximum deflecting angle is provided. In this way, when the wheel reaches the maximum deflecting angle, the pilot circuit conduction device is operated, and a pilot circuit of a relief valve or unload valve is conducted, so as to decrease a circuit pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a motor vehicle or a mobile crane that hydraulically steers a plurality of wheels in synchronization with each other.

[0002]

2. Description of the Related Art In a steering apparatus of an automobile which is steered by hydraulic pressure, a steering wheel is rotated in accordance with rotation of the steering wheel.
There is an orbit roll that supplies pressure oil from a pump to the steering cylinder and controls the stroke (and therefore the steering angle) of the steering cylinder in accordance with the rotation angle of the steering wheel. If it is attempted to rotate the steering wheel more than the stroke, even if the steering cylinder has reached the maximum stroke, high pressure oil from the pump will continue to be supplied to the steering cylinder due to its structure. If the high-pressure hydraulic oil is continuously supplied to the steering cylinder in this manner, the steering circuit and members including the steering cylinder on which the hydraulic oil acts may be damaged, so that the hydraulic oil acting on the steering cylinder does not exceed the set value. As described above, a relief valve is provided to protect a steering circuit and members including a steering cylinder from excessive high pressure. There are the following problems when applying a steering device equipped with this relief valve to an automobile or a crane truck which has two or more front wheels or rear wheels and which are connected by a ring gauge and steer synchronously.

[0003]

For the sake of simplicity, a description will be given of a case where two-axle wheels are steered in a synchronized manner. Is the same. When the steering wheel is operated to the maximum, the pump sends the maximum pressure oil to the steering cylinders of the first and second shafts, and the stroke of the cylinder is maximized (the stroke of the other cylinder at the symmetrical position is Minimum) and the wheels are fixed so that they do not rotate any further. At this time, if each of the steering cylinders of the first shaft and the second shaft reaches the maximum stroke at the same time, almost no tension or compression force acts on the linkage connecting the first shaft and the second shaft, and there is no problem.

However, the strokes of the cylinders of the first and second shafts do not always become the maximum or minimum at the same time due to differences in the manufacturing accuracy of the steering cylinder, and the strokes of the cylinders of either shaft are reduced. It becomes the maximum or minimum first. Then, the stroke of the cylinder becomes maximum (minimum) on one axis and the steering of the wheels is fixed, but on the other axis, there is a margin in the stroke of the cylinder and the wheels are steered. In this case, the hydraulic pressure does not act on the shaft side (cylinder stroke end) on which the wheels are already fixed to the linkage connecting the first shaft and the second shaft, but the cylinder on the shaft side on which the other wheel is not fixed. , A high tensile or compressive force is applied to this linkage, which may cause breakage. Accordingly, the present invention provides a steering apparatus for an automobile that hydraulically steers a plurality of shafts in a synchronized manner, and that even when the steering wheel of the steering is operated to the maximum, an excessive load is not applied to the linkage connecting the plurality of shafts. It is an object of the present invention to provide a steering apparatus for an automobile in which the linkage is not likely to be damaged.

[0005]

In order to achieve the above object, the present invention employs the following automobile steering apparatus. That is, in this automobile steering apparatus, in a vehicle steering apparatus that hydraulically steers a plurality of axes of wheels in synchronization with each other, the time when the maximum deflection angle of the wheels is reached is greater than the time when the maximum deflection angle of the wheels of other axes is reached. A shaft configured to be slightly faster, and a pilot circuit conducting device that operates when a wheel of the shaft reaches a maximum deflection angle to conduct a pilot circuit of a relief valve or an unload valve; Reaches the maximum deflection angle,
The pilot circuit conducting device is operated, the pilot circuit of the relief valve or the unload valve is conducted, and the hydraulic pressure supplied from the hydraulic pump to the steering cylinder of each shaft decreases.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a crane vehicle which steers two wheels in synchronization will be described below with reference to the drawings. FIG. 2 shows a wheel steering mechanism at the front of the vehicle body. 2, the right side corresponds to the front of the chassis 10 and the left side corresponds to the rear of the chassis 10. As shown in FIG. 2, the foremost first shaft 20 is a knuckle arm 22 of the left and right wheels.
a, 22b and the axle 23 are connected at the center of rotation of the wheels,
A pair of left and right steering cylinders 25a and 25b are provided between the ends of the left and right knuckle arms and the axle, respectively, and the ends of the left and right knuckle arms are connected by a linkage 24. The second axis is configured similarly to the first axis. However, the time when the steering cylinders 35a and 35b of the second axis have the maximum or minimum stroke, that is, the time when the wheel is at the maximum deflection angle is the first axis.
It is configured to be slightly faster than the axis. In order to configure the second shaft in this manner, for example, the stroke of the steering cylinder of the second shaft may be changed, or the position of attachment of the second shaft to the axle may be changed. As shown in FIG. 2, a linkage 40 is connected between the first shaft and the second shaft, and the wheels of the first shaft and the second shaft are synchronously operated by hydraulic oil supplied from a hydraulic pump. Can be oriented.

When the right wheel 31a of the second shaft is deflected to the right by the maximum angle, a mechanical valve 45a is attached to the axle 33 at a position where the member (A shown in FIG. 2) of the knuckle arm 32a contacts the tip thereof. The mechanical valve 45b is positioned at a position where the member (B shown in FIG. 2) of the knuckle arm 32b comes into contact with the tip of the knuckle arm 32b when the left and right symmetric left wheels 31b are deflected to the left by the maximum angle.
Is arranged. These mechanical valves 45a, 45
b operates when the wheel of the second shaft reaches the maximum deflection angle, conducts the pilot circuit of the relief valve 90 as described later, and has a function of lowering the oil pressure by flowing the pressurized oil to the tank. It is.

FIG. 1 is a circuit diagram of the present embodiment. The present embodiment is provided with a circuit including a relief valve 90 and mechanical valves 45a and 45b as shown in FIG. 1, which is different from the conventional one and the other is the same. In the figure, a rotary seal 50 is a joint connecting the swivel base supported on the vehicle body 10 and the vehicle body 10, and a circuit above the rotary seal 50 is attached to a swivel base including a driver's seat, and a lower circuit is a vehicle body. 10 is attached. The orbit roll 80 supplies pressure oil to the steering cylinder in accordance with the rotation of the steering wheel, and the priority valve 70 supplies pressure oil from the pump 60 to the orbit roll 80 with priority.

When the driver turns the steering wheel to the right, the hydraulic pressure of the circuit 81 becomes higher than the hydraulic pressure of the circuit 82, and the first hydraulic pressure shown in FIG.
Shaft, second shaft steering cylinders 25a, 25b, 3
The hydraulic pressure acts on the right chambers of 5a and 35b, the piston moves to the left against the load, and the wheels of the first shaft and the second shaft rotate to the right in synchronization. When the steering wheel is turned to the left, on the contrary, the hydraulic pressure of the circuit 82 becomes higher than the hydraulic pressure of the circuit 81, and the steering cylinders 2 of the first shaft and the second shaft shown in FIG.
The hydraulic pressure acts on the left chamber of 5a, 25b, 35a, 35b, the piston moves to the right against the load, and the wheels of the first shaft and the second shaft rotate to the left synchronously.

As shown in FIG. 1, pressure oil from a pump 60 passes through a circuit 62, a priority valve 70, an orbit roll 80, and a steering cylinder 25 of the first shaft.
a, 25b, the second-axis steering cylinder 35a, 3
5b. The relief valve 110 is for preventing the hydraulic pressure acting on each steering cylinder from exceeding a set value. Circuit 63 from pump 60
Is provided with a relief valve 90 and mechanical valves 45a and 45b unique to this embodiment. When the mechanical valves 45a and 45b do not operate, the circuit 63 and the circuit 42 conduct and the same pressure is applied to the relief valve 90. The maximum value of the hydraulic pressure applied to the steering cylinder is defined by the relief valve 110.

As described above, the second-axis steering cylinders 35a, 35b have the maximum or minimum stroke before the first-axis steering cylinders 25a, 25b, and at that time, one of the mechanical valves 45a, 45b is turned off. When activated, the circuits 41 and 42 conduct. Then, a pressure difference occurs in a section inside the relief valve 90,
Since the circuit 63 and the circuit 64 are conducted and the set pressure 90 lower than that of the relief valve 110 is operated, the set pressure is lower than when the mechanical valve is not operated, so that high-pressure oil acts on the steering cylinders 25a and 25b. There is no possibility that the linkage 40 is broken. In this embodiment, a mechanical valve is used as the pilot circuit conduction device. However, a limit switch, a proximity switch, or the like is used to detect that the wheel of the second shaft has reached the maximum deflection angle, and switch the valve based on the signal. May be used as a pilot circuit conducting device. Further, an unload valve may be provided instead of the relief valve 90. It is necessary to use a relief valve to prevent the wheels from returning from the maximum deflection angle in a vehicle with a large wheel return force, but to use a unload valve in a vehicle with a small wheel return force. Since the maximum deflection angle can be substantially maintained, the relief valve and the unload valve may be selected according to the type of the vehicle.

[0012]

In the vehicle steering apparatus according to the present invention, when the wheels of a plurality of shafts are hydraulically steered in synchronization with each other, the shaft having the maximum deflection angle slightly earlier than the other shafts and the shaft thereof And a pilot circuit conducting device which operates when the steering wheel reaches the maximum deflection angle, and when the steering wheel is operated to the maximum degree and the wheels reach the maximum deflection angle, the pilot circuit conducting device operates to operate the circuit pressure. Therefore, there is no possibility that the high hydraulic pressure acts on the steering cylinder and the linkage connecting the plurality of shafts is damaged.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is a schematic view of a steering mechanism according to one embodiment of the present invention.

[Explanation of symbols]

 10 chassis 20 first shaft 21a, 21b wheel 22a, 22b knuckle arm 23 axle 24 linkage 25a, 25b steering cylinder 30 second shaft 31a, 31b wheel 32a, 32b knuckle arm 33 axle 34 linkage 35a, 35b steering cylinder 40 first shaft 45a, 45b Mechanical valve 50 Rotary seal 60 Pump 70 Priority valve 80 Orbit roll 90 Relief valve 100 Tank 110 Relief valve

Claims (1)

[Claims] 1. In a steering apparatus for an automobile that hydraulically steers a plurality of wheels in synchronization with each other, a time point when a maximum deflection angle of a wheel is reached is slightly earlier than a time point when a maximum deflection angle of a wheel of another axis is reached. And a pilot circuit conducting device that operates when the wheel of the shaft reaches the maximum deflection angle to conduct the pilot circuit of the relief valve or the unload valve, wherein the wheel has the maximum deflection angle. , The pilot circuit conducting device is operated, the pilot circuit of the relief valve or the unload valve is conducted, and the hydraulic pressure supplied from the hydraulic pump to the steering cylinder of each shaft decreases. Steering device.