JPS63265768A - Hydraulic steering device - Google Patents

Abstract

PURPOSE:To advance the operation of a servo cylinder more than the displacement of a main cylinder and to improve the responsiveness of the system by linking the servo cylinder through a spring to a knuckle arm which is operated by the main cylinder. CONSTITUTION:To a main cylinder 7, a pressure oil is fed by a main pump 9 through the operation of a main control valve 8, and the operation of the main cylinder 7 is delivered to a knuckle arm 6. The knuckle arm 6 is connected to a servo cylinder 4 through a spring 5, and pressure oil is fed from a pilot pump 10 to the servo cylinder 4. Since the operation of the servo cylinder 4 is carried out through the spring 5, it is advanced by the amount of bending of the spring 5 more than the displacement of the main cylinder 7, and the feedback of a pilot valve 2 at the starting of steering the handle is made rapidly.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a hydraulic steering device for an industrial vehicle.
It is particularly suitable for use in hydraulically steering a wheeled vehicle that uses hydraulic power as power for steering, where the oil flow rate and vehicle weight are large and steering control is difficult.

(Prior Art) Hydraulic steering devices for industrial vehicles require larger amounts of power and oil flow rate for steering than those of passenger cars, etc.
There are also constraints due to vehicle configuration.

Generally, the linkage type shown in Figure 2 is used.

The fully hydraulic type shown in Figure 3 is often used.

In other words, the linkage type shown in Figure 2.

a is the steering handle, b is the control valve,
C is a gear box, d is a steering cylinder, e is an arm, and f is a pump. When steering wheel a is turned, control valve b is activated via a linkage mechanism.
The plunger moves and pressure oil flows into the steering cylinder d, which operates and rotates the arm e. When arm e rotates, control valve b
Feedback is applied to, and control valve b is
A flow rate of pressure oil is supplied to the cylinder d commensurate with the rotational speed of the handle a.

Also in FIG. 3, which is a fully hydraulic type.

A indicates a fully hydraulic steering valve. Control valve b is now activated by input from steering wheel a.
When is activated, the pressure oil sent from the hydraulic pump f flows into the cylinder circuit and the steering cylinder d is activated.
Arm e rotates. At this time, control valve b receives feedback for the amount of rotation of rotor g, and handle a
A flow rate of pressurized oil to cylinder d commensurate with the rotational speed of is supplied.

(Problems to be Solved by the Invention) The linkage type steering device shown in FIG.
Since the displacement after the cylinder is fed back, a smooth operation feeling can be obtained, but in vehicles with a large vehicle weight or oil volume, the hydraulic steering system is The response of the system cannot be improved, and the delay in response often becomes a major problem, especially when starting to operate the steering wheel.

In addition, in the fully hydraulic type shown in Figure 3, hydraulic feedbank is performed by the rotor g, so the response of the hydraulic system can be increased compared to the one in Figure 2, and it is also connected to the cylinder with hydraulic piping. Since it has a linkage 2, it has features such as a high degree of freedom in terms of layout, and is now being widely used instead of the linkage 2.

However, in a fully hydraulic type, feedback is taken within the hydraulic system, so the entire hydraulic steering system does not form a closed loop, resulting in a deviation between the steering wheel angle and cylinder displacement. Since it does not have a mechanical feedbank mechanism, it has problems such as misalignment between the handle angle and cylinder displacement due to oil leakage. And especially like forklifts and shovel loaders.

Vehicles equipped with a knob on the steering wheel have a problem in that the knob is misaligned with respect to the direction of travel, impairing steering operability.

An object of the present invention is to solve the above problems.

(Means and effects for solving the problems) The present invention has been made in view of the above points, and includes a servo cylinder to which pressure oil is supplied from a pilot pump by operation of a pilot valve operated by a steering handle. .

a main cylinder to which pressure oil is supplied from a main pump by operation of a main control valve operated by pressure oil controlled by the pilot valve, and the knuckle arm or other rotating member operated by the main cylinder This is made up of servo cylinders connected via a spring, which eliminates misalignment between the steering handle and the knuckle arm or other rotating parts, and in order to operate the servo cylinder via the spring, the main cylinder is moved by the amount of deflection of the spring. Since it was decided that the change would proceed faster than the displacement, the pilot valve's feedbank was quickly activated when the steering wheel began to be turned to improve the response of the system.

(Example) Next, embodiments of the present invention will be described based on the drawings.

In FIG. 1, numeral 1 is a steering handle, and numeral 2 is a pilot valve which is operated by the difference in rotation between the rotation of the steering wheel 1 and a gear 3 connected to a servo cylinder 4. 5 is the spring, 6 is the knuckle arm (
or rotating member). 8 is a main control valve, which is operated by pressure oil from the pilot pump 10 when the pilot valve 2 is operated. When the main control valve 8 is actuated, the pressure oil from the main pump 9 is sent to the main cylinder 7, and the knuckle arm 6 or other rotating member rotates nine times. A servo cylinder 4 that is operated by being supplied with oil is mechanically connected via a spring 5.

Therefore, there is no misalignment between the steering handle 1 and the knuckle arm 6 or other rotating members.

Also, since the operation of the servo cylinder 4 is via the spring 5, the main cylinder 7 is moved by the amount of deflection of the spring 5.
Since the feed bank of the pilot valve 2 is quickly performed when the steering wheel 1 starts to be turned, the response of the system can be increased.

Therefore, according to the embodiments of the present invention, the entire steering system is constructed as a so-called closed loop, and the response at the start of operation is delayed.

By providing relative displacement between the servo cylinder and the main cylinder, the problems of the prior art described above can be solved.

(Effects of the Invention) This invention is constructed as described in detail above, and there is no misalignment between the steering handle and the knuckle arm or other rotating members, and since the servo cylinder is operated via a spring, the amount of deflection of the spring is sufficient. Since the displacement proceeds from the displacement of the main cylinder, the feed bank of the pilot valve is quickly performed when the steering wheel starts to be turned, and the responsiveness of the system can be improved.

Therefore, according to the present invention, the conventional problem of misalignment between the steering wheel angle and cylinder displacement due to oil leakage can be solved, and in addition, in a vehicle having a knob on the handle, the knob position may be misaligned with respect to the direction of travel. It is possible to obtain a hydraulic steering device that does not impair steering operability, is suitable for use in vehicles with large oil flow rates and large steering power, and has extremely high responsiveness. In addition, the pilot valve and servo cylinder that make up this device have the same configuration as the so-called conventional Integral 2 hydraulic steering device, so the entire device can be made by combining the configurations of existing parts, reducing costs. It has advantages.

[Brief explanation of drawings]

FIG. 1 shows a steering hydraulic circuit according to an embodiment of the present invention, and FIGS. 2 and 3 each show two examples of conventional hydraulic circuits. 1... Steering handle. 2... Pilot valve, 4... Servo cylinder. 5... Spring, 6... Knuckle arm. 7...Main cylinder. 8...Main control valve. 9...Main pump. 10...Pilot pump. Patent Applicant Komatsu Ltd. Agent (Patent Attorney) Osamu Matsuzawa Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A servo cylinder is provided to which pressure oil is supplied from a pilot pump by the operation of a pilot valve operated by the steering handle, and by the operation of a main control valve which is operated by pressure oil controlled by the pilot valve, pressure oil is supplied from the main pump. A main cylinder is provided, and the servo cylinder is connected via a spring to a rotating member such as a knuckle arm operated by the main cylinder.
Hydraulic steering device.