JPS63195064A - Fully-hydraulic power steering device - Google Patents

Abstract

PURPOSE:To control a sudden pressure variation in a steering valve unit, by installing a solenoid opening/closing valve, compensating dislocation between a handwheel turning angle and a steering wheel angle, in a bypass line connecting symmetrical hydraulic lines of the steering valve unit. CONSTITUTION:On the basis of each detection signal out of a rotary encoder 18 detecting a turning angle of a handwheel 1 and a potentiometer 21 detecting a steering angle of a steering wheel 19, dislocation of the handwheel 1 to the steering wheel 18 is calculated by a controller 22. In consequence, when the dislocation is laser than the steering wheel 19, a solenoid opening/closing valve 18 is opened and a hydraulic fluid to a power cylinder 8 is put back to a tank 11 from a bypass line 16 via a valve unit 3, compensating the dislocation. At this time, since the return oil passes through a throttle valve 14 of a rotary valve 4, a sudden pressure variation inside the valve unit 3 is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fully hydraulic power steering system used in industrial vehicles such as forklifts.

(Prior Art) In general, a fully hydraulic power steering device is equipped with a steering valve unit (operated by a steering wheel).
It consists of a power cylinder that steers the steering wheel, and left and right hydraulic lines that connect the steering valve unit and the power cylinder, and is proportional to the rotation angle of the steering wheel. By supplying an amount of hydraulic oil to the power cylinder via the steering valve unit, the steering wheel is steered by oil J3:il. However, in the above-mentioned fully hydraulic power steering device, there is no mechanical connection between the rotation angle of the steering wheel and the steering angle of the steered wheels due to the leakage of hydraulic fluid in the steering valve unit. This can cause misalignment between the handlebars, especially when the steering wheel is equipped with a knob, such as those in Fee Clearer 1~. There is a problem with tatsuzuru.

Therefore, in order to solve the above problem, a hydraulic oil outflow line for positional deviation correction is installed in the hydraulic line that supplies hydraulic oil to the power cylinder, and the difference between the target stroke of the power cylinder and the actual stroke corresponding to the handle rotation angle is It has been proposed that the electromagnetic switching valve of the hydraulic oil outflow line is operated to switch when the hydraulic oil outflow line exceeds a set value to cause the hydraulic oil to flow out and correct the positional deviation of the u1 handle (for example,
(See Japanese Patent Application Laid-Open No. 60-261779).

(Problems to be Solved by the Invention) However, the above-mentioned conventional fully hydraulic power steering device with a positional deviation correction function trains the hydraulic oil supplied from the steering valve unit to the power cylinder directly to the oil tank and adjusts the positioning. Since this is a method for correcting deviation, the hydraulic oil, which is normally 60 M/cj, is released to the tank side pressure OKy/ci, resulting in severe pressure fluctuations inside the steering valve unit, and the pressure inside the unit. The imbalance causes problems such as wear and damage to the rotary valve and metering device, as well as the generation of abnormal noises.Also, the electromagnetic switching valve needs to be operated separately when turning to the right and when turning to the left. ? t(la
There is a problem that the l;/l switching valve becomes complicated and inefficient.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fully hydraulic power steering system c) capable of eliminating the above-mentioned conventional problems.

(Means for Solving the Problems) The present invention for solving the above problems provides a steering valve unit that is operated by a handle, a power cylinder that steers a steering wheel, and a connection between the steering valve unit and the power cylinder. In the fully hydraulic power steering system, the fully hydraulic power steering system is equipped with left and right hydraulic lines to hydraulically operate the steering wheel in response to the operation of the steering wheel,
The main point is that the left and right hydraulic lines are connected by a bypass line, and this bypass line is equipped with an electromagnetic on-off valve that is operated to open and close in order to correct the positional deviation between the steering wheel rotation angle and the steering wheel turning angle. do.

(Function) Therefore, when the steering wheel is rotated, if the rotation angle of the steering wheel and the steering angle of the steering wheel do not match due to oil leakage in the steering valve unit, the electromagnetic on-off valve will move to the passage opening side. The hydraulic fluid that is switched and sent to the power cylinder is returned to the steering valve unit through the bypass line, thereby correcting misalignment between the steering wheel and the steering wheel.

(Example) Hereinafter, an example of the present invention will be specifically described based on an open view. In the hydraulic circuit diagram shown in FIG. 1, 1 is a handle having a knob 2 for improved operability, 3 is a steering valve unit operated by the handle 1, and this steering valve unit 3 is operated by the handle 1. A rotary valve 4 for steering that is directly operated, a lever mechanically interlocked with the rotary valve 4, and a hydraulic pump 9 that sends hydraulic fluid through the rotary valve 4 through a hydraulic line 6.7 to the steering wheel 1. It is composed of a metering device (generally called a meter) 5 that supplies oil j corresponding to the rotation angle of the power cylinder 8 to the power cylinder 8. A relief valve 11 is an oil tank that maintains the pressure at a set pressure.

The L1-tariff valve 4 also has a throttle valve 12 in the passage connecting the tank boat 1 and the metering boat, a throttle valve 13 in the passage connecting the tank boat and the cylinder boat, and a throttle valve 13 in the passage connecting the tank boat 1 and the metering boat. A throttle valve 14 is installed in the passage connecting the boat, and a full throttle valve 15 is installed in the passage connecting the pump boat and the tank boat 1.
Of these throttle valves, there are normally 3 metering boats and 3 cylinder boats! The degree of restriction of the throttle valve 14 provided in the connecting passage is set to the maximum. Further, a hydraulic line 6 communicating with the left oil chamber of the power cylinder 8 and a hydraulic line 7 communicating with the right oil chamber are communicated with each other by a bypass line 16, and this bypass line 16 has a type that allows hydraulic oil to flow in both directions. An electromagnetic on-off valve 17 for opening and opening the passage is provided.

- On the other hand, the steering wheel shaft 1a of the handle 1 is provided with a rotary encoder 18 of C as a rotation angle detector, and an incremental output (
A reference point signal (a signal indicating the reference position of the knob) corresponding to the position of the knob 2 for detecting the phase A and phase B) and the rotation angle is output. Further, a potentiometer 21 as a turning angle detector is attached to the king pin 20 of the steered wheel 19, and outputs an actual turning angle signal of the steered wheel 19. The controller 22 manually inputs each detection signal from the L1-tary encoder 18 and the potentiometer 21, and outputs a control signal to the solenoid valve 17 based on the detection signals.

The present embodiment is constructed as described above, and therefore, when the steering wheel 1 is rotated clockwise or counterclockwise, the rotary valve 4 in the steering valve unit 3 changes from the neutral position It(b) when traveling straight to the clockwise turning position. (a) or left rotation position II (c), and the hydraulic oil sent from the hydraulic pump 9 via the rotary pulp 4 is transferred to the metering device 5.
Accordingly, the hydraulic fin 6 or 7 is supplied with an amount of oil corresponding to the rotation angle of the C handle 1 to the left oil chamber or the right oil chamber of the power cylinder 8, and the steering wheel 19 is steered to the right or left.

Then, the C position deviation correction action is carried out in the above-mentioned steering operation section.Hereinafter, the operation will be explained according to the flowchart t7-1 in FIG. A detection signal of the rotation angle is input.C1 In response to this detection signal, the controller 22 calculates the intended turning angle of the steering wheel 14 as the target turning angle TO.Subsequently, the actual turning angle TO is determined by the robot meter 21. The turning angle TO is detected, and the controller 22 calculates the deviation angle θ between the turning angle TO of the steered wheels 14 and the actual turning angle TO.

Next, the rotation direction of the steering wheel 1 is determined based on the incremental output from the rotary encoder 18, and the solenoid SQL of the electromagnetic on-off valve 17 remains inactive when driving straight, and when turning, the rotation direction of the handle 1 is determined. If the rotation angle of the steering wheel is ahead of the actual turning angle of the steering wheels 14, the solenoid SQL remains inactive, but if it is delayed, the solenoid SQL is activated for a short time to control the electromagnetic light. Open valve 17. As a result, the hydraulic oil supplied to the power cylinder 8 via the steering pulp unit 3 is returned to the steering valve unit 3 through the bypass line 16. That is,
When the rotation angle of the handle 1 is in the direction of rotation, the steering wheel 14
By opening the bypass line 16 and returning the hydraulic oil sent to the power cylinder 8 to the oil tank 11 via the steering valve unit 3, only when the steering wheel 1 lags behind the actual turning angle, the steering wheel 1 is rotated idly and the position is shifted. performs a corrective action.

Next, the actual correction angle δθ due to the correction action is calculated, and the post-correction deviation angle θ1 is calculated from the deviation angle 0 before correction and the correction angle δθ. If not, repeat the same action.

That is, in the power steering system 8 of this embodiment, the steering wheel is controlled by the C controller 1 to the roller 22 based on detection signals from the rotary encoder 18 that detects the rotation angle of the steering wheel 1 and the potentiometer 21 that detects the turning angle of the steering wheel 19. The positional deviation of the steering wheel 1 with respect to the steering wheel 18 is calculated, and the positional deviation is π from the steering wheel 19 in the rotation direction.
The electromagnetic quantity m-valve 18 is opened only when the hydraulic oil is supplied to the C power cylinder 8 from the bypass line 16 via the steering valve unit 3 to the oil tank 1.
1. By returning to 1, the handle 1 relative to the steering wheel 19 is
The positional deviation at the end of rotation of the handle 1 can be kept within a minute range. At this time, since the return oil passes through the throttle valve 14 of the rotary pallet 14, the throttling effect of the throttle valve 14 prevents significant pressure fluctuations within the steering pulp unit 3.

Next, another embodiment of the present invention shown in FIG. 3 will be described.

This embodiment is an example in which electric taWI quiet valves 17A, 17[3 of the type in which the hydraulic oil flows in the direction shown in the figure are used, and a bypass line 16A that interconnects the hydraulic lines 6.7 is used. , 16B, electromagnetic on-off valves 17A, 17B and check valve 23Δ.

23B is provided in the opposite direction. J3, check valves 23A, 2313 are fRfal? I flll valve 1
When 7A or 17B is interposed for positional deviation correction, if a strong load is applied to the steering wheel 14 in the opposite direction to the steering direction, the pressures on the high pressure side and the low pressure side of the power cylinder 8 are reversed, causing electromagnetic Open/close valve 17A.

Since there is a possibility that the flow of oil in 17[3 will flow backwards, the arrangement is made to prevent this.

Therefore, regarding the positional deviation correction effect according to this embodiment, when turning to the right, the solenoid 5OL1 of the electromagnetic on-off valve 17A
An activation signal is output to the electromagnetic rM on-off valve 7 when turning left.
This embodiment differs from the previous embodiment in that a drive signal is output to the solenoid 5QL2 of B, but other operations are similar to the previous embodiment.

(Effects of the Invention) As described in detail above, according to the present invention, when a deviation occurs in the relative position of the steering wheel with respect to the steering wheel, part of the hydraulic oil supplied to the power cylinder is transferred to the oil tank. By returning the steering wheel to the steering wheel, the steering wheel can be rotated idly to correct its misalignment.In particular, the hydraulic oil is returned through the steering valve unit, so even though it is a return type of hydraulic oil, Due to the throttling effect of the throttle valve installed in the steering bulge 1 unit, sudden pressure fluctuations inside the C valve unit can be suppressed, reducing wear of the rotary valve, metering device, or seal part in the steering bulge unit I. , f1 injury and even Yasutomi can be prevented from occurring.

In addition, the present invention has a method C in which the left and right hydraulic rains connecting the steering valve unit and the power cylinder are connected by a bypass line, and this is opened 1.1Jill by an electromagnetic f71111 valve, so that the left and right oil chambers of the power cylinder are connected to each other. Compared to the conventional type, which communicates with the oil tank through a hydraulic oil outflow line and switches it with a 3-position electromagnetic switching valve, it is possible to provide a more efficient and simpler electromagnetic valve with a simpler structure. The configuration can also be simplified.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a hydraulic circuit diagram, FIG. 2 is an operation flow diagram p-1, and FIG. 3 is a hydraulic circuit diagram showing another embodiment. 1... Handle 3... Steering valve unit 6.7... Hydraulic line 8... Power cylinder 1
6...Bypass line 17...Electromagnetic Fdll! Valve 18...Rotary encoder 19...Steering wheel 21...Potentiometer Applicant Toyota Industries Corporation Agent
Patent attorney Hidehiko Okada (3 others) Figure 2

Claims (1)

[Claims] The steering valve unit includes a steering valve unit that is operated by a steering wheel, a power cylinder that steers the steering wheel, and left and right hydraulic lines that connect the steering valve unit and the power cylinder, and that controls the steering wheel in response to the operation of the steering wheel. In a hydraulically operated fully hydraulic power steering system, the left and right hydraulic lines are connected by a bypass line, and this bypass line has an electromagnetic opening/closing system that is operated to open and close to correct misalignment between the steering wheel rotation angle and the steering wheel turning angle. Fully hydraulic power steering device equipped with a valve.