JPH02147474A - Phase shift correcting method for full-hydraulic power steering device - Google Patents

Abstract

PURPOSE:To prevent a steering wheel from idling and enhance the durability and maintenance easiness of a solenoid valve by feeding working oil to a power cylinder via solenoid valve on a bypass line, correcting phase shift of steering wheel with respect to car wheels to be steered, and by interrupting the correction during straight running. CONSTITUTION:When a phase difference between a steering wheel 1 and car wheels to be steered 20 is sensed, a solenoid valve 17 installed on a bypass line 16 leading between hydraulic lines 6, 7 is opened, and the working oil to power cylinder 8 is bypassed so as to correct the phase shift. On this control/ correction system the solenoid valve 17 is closed whether such phase shift exists or not in the neutral position in which a rotary valve 4 in a steering valve unit 3 is for straight running, to interrupt correction of phase shift. In case opening of solenoid valve exceeds an allowable period of time and the steering wheel 1 is at a standstill, the solenoid valve 17 is shut to prevent coil from overheating and avoid unnecessary oil pressure to be applied to the power cylinder 8.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for correcting a phase shift in a fully hydraulic bower swaying device used in a battery forklift, etc. This invention relates to the maintenance of a bypass solenoid valve that corrects the deviation and to an improvement in the method of correcting the phase deviation to prevent the steering wheel from drifting when driving straight ahead.

[Prior Art] In general, a fully hydraulic power steering device has a steering valve unit (mouth to
It consists of a power cylinder that steers the steering wheel, and a series of 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 the suspended hydraulic oil to the power cylinder via the steering valve unit, the steered wheels are hydraulically steered.

However, unlike a mechanical transmission mechanism, the all-hydraulic power steering link described above is susceptible to the leakage of hydraulic fluid in the steering valve unit, and the control of the steering wheels based on the rotation angle of the steering wheel. The actual cutting angle may deviate from the target cutting angle, and as a result, for forklifts with knobs on the handle like the forklifts 1 to 1, the neutral position of the steering wheel when traveling straight is out of order, causing problems for the driver. There are problems in that it gives a sense of discomfort and impairs operability.

To solve this problem, we installed a solenoid valve that bypasses the hydraulic oil supplied to the power cylinder, and detected the phase shift between the target turning angle of the steered wheels based on the rotation of the steering wheel and the actual turning angle, and activated the solenoid valve. A phase shift correction method has been proposed in which the above-mentioned shift is corrected by idling the handle caused by bypassing the supplied hydraulic oil to the power cylinder.

In the above-mentioned conventional phase shift correction method, as shown in 70-chiset in FIG. Find the phase shift θ-(target angle - actual angle) and find e
< In the case of 4, that is, when the actual turning angle of the steered wheels is too advanced than the target turning angle, the steering wheel is idled through the WS solenoid valve. Furthermore, if there is any deviation as mentioned above when the handle is stopped, the solenoid valve is inserted between the valves, thereby preventing unnecessary hydraulic pressure from being applied to the power cylinder due to abnormal causes such as the above-mentioned leak, as well as immediately preventing the hydraulic pressure from being applied to the power cylinder when the next handle starts rotating. Misalignment correction is performed.

[1! Problems that Akira would like to solve: However, in the fully hydraulic power steering Ml that performs phase shift correction as described above, the hydraulic oil is supplied to the power cylinder according to the rotation angle of the steering wheel, so there is no waste. However, under normal conditions, if the handle rotation stops, hydraulic oil is not supplied to the power cylinder), so if the handle rotation stops when there is the above deviation, the deviation will not be corrected and the electromagnetic If the valve continues to open, there is a risk that the coil of the solenoid valve will overheat, resulting in insulation deterioration or, in the worst case, dielectric breakdown.

In addition, since the deviation correction is performed in the same way while the vehicle is running straight, the T1 movement of the steering wheel (
This has the disadvantage of causing unsteadiness.

The technical problems to be solved by the present invention are to maintain the electromagnetic valve and to prevent the steering wheel from becoming M8 when traveling straight ahead.

[Means for solving the yI problem] In order to solve the above problem, the present invention detects the deviation between the eye 4ff turning angle of the steering wheel based on the rotation of the steering wheel and the actual turning angle,
By opening the solenoid valve installed in the bypass line, the hydraulic oil supplied to the power cylinder is bypassed and the above deviation is corrected. A novel configuration is adopted in which a command is issued to interrupt the deviation correction when the handle is stopped.

[Function] In 'IAe' where the above deviation occurs even when the handle is stopped, including when the handle is stopped, the solenoid valve is not allowed to open for a predetermined period of time when the overheating of the solenoid valve coil is within the allowable range. This prevents unnecessary hydraulic pressure from being applied to the power cylinder due to abnormal causes such as the above-mentioned leak, and also promptly corrects the deviation when the next handle rotation starts.

Then, at ', the opening of one magnetic valve exceeds the above predetermined time 311
In this case, the solenoid valve is closed only when the handle is stationary, so the coil of the solenoid valve is safely protected.

Also, when driving straight, regardless of the presence or absence of the above deviation, '/H
Since the '6tJ valve is closed and the deviation correction is interrupted, the handle is reliably prevented from swinging.

[Example 1] Hereinafter, an example of the present invention will be specifically described based on the drawings. In the hydraulic circuit diagram shown in FIG. 1, 1 is a handle equipped with a knob 2, 3 is a steering valve unit operated by the handle 1, and this steering valve unit 3 is a steering valve unit operated directly by the handle 1. The rotary valve 4 is mechanically interlocked with the rotary valve 4, and the hydraulic oil sent from the hydraulic pump 9 through the rotary valve 4 is passed through the hydraulic line 6.7 to the power cylinder with an oil amount corresponding to the rotation angle of the handle 1. It consists of a metering device (referred to as a jitter in the shell) 5 which supplies the metering device to the metering device 8. By the way, 10 in the figure is a relief valve that maintains the pressure in the circuit at the set pressure, 1
1 is an oil tank.

The rotary pal 14 has a throttle valve 12 in the passage connecting the tank boat and the metering boat, a comparison 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 and the cylinder boat. A comparison valve 14 is provided in the passage communicating with the cylinder, and a fully suspended throttle valve 15 is provided in the passage connecting the pump boat and the tank. Among these throttle valves, in the normal case,
The degree of restriction of the throttle valve 14 provided in the passage connecting the metering boat and the cylinder boat is set to the maximum. In addition, a hydraulic line 6 communicating with the rond side oil chamber of the power cylinder 8 and an oil/moline 7 communicating with the head side oil chamber are communicated with the phase n by a bypass line 16, and this bypass line 16 has a hydraulic oil flow. A solenoid valve 17 is provided for the permissive type of passage IMll. In addition,
This solenoid valve 17 is a normally open on-off valve with bidirectional passage.

On the other hand, the steering shaft 1a of the handle 1 is provided with a rotary encoder 19 as a rotation angle detector,
It outputs an incremental output (A phase/B phase) for determining the turning direction and a reference point signal (signal indicating the reference position of the knob) corresponding to the position of the knob 2 for detecting the rotation angle. Further, a potentiometer 22 as a turning angle detector is attached to the king pin 21 of the steered wheel 20.
Outputs an actual angle signal of 0. And the skit []-
523 inputs each detection signal from the rotary encoder 19 and the potentiometer 22, and outputs a control signal 13 to the solenoid valve 17 based on the detection signals.

An apparatus for carrying out the present invention (constructed as described above), when the handle 1 is rotated 41 turns or counterclockwise,
The rotary valve 4 in J3 of the steering valve unit 3 moves from the neutral position "I (b) when traveling straight to the right turning position (a)
Or, it is switched to the left rotation position (C), and the hydraulic oil sent from the hydraulic pump 9 through the rotary valve 4 is sent via the hydraulic line 6 or 7 by the metering device 5 in an oil amount corresponding to the rotation angle of the handle 1. The rod-side oil fork of the power cylinder 8 is supplied to the head-side oil chamber, and the steering wheel 20 is steered to the right or left.

The phase shift correction action is performed during the above-mentioned steering operation, and the action will be explained below with reference to the flowchart of FIG.

First, after turning on the power, the initial setting is performed (8100), and the rotary encoder 19 outputs a detection signal of the steering wheel rotation angle (3102>. Then, in response to this detection signal, the controller 23 determines the turning angle of the steering wheel 20 that should be the original one. The target angle Tθ is !tn<8104).

Subsequently, the actual turning angle To of the steered wheel 20 is detected by the potentiometer 22 (S106), and the controller 1 to roller 2
3, the deviation angle θ between the target angle Tθ and the actual angle TO is calculated <8108>.

Next, detect whether flag A is 1 (5110),
At first, it is O, so the process goes to 8112 to detect whether the opening of the solenoid valve 17 exceeds a predetermined time T (here, it is set to 1 minute), and at first, 'FII! Since the i-valve 17 is closed, the process proceeds to 8120 and flag 8 is set to O.

Next, the rotation direction of the handle 1 is determined based on the incremental output from the []-Tatsuri encoder 1.
122), when turning to the left or right, if the rotation angle of the steering wheel 1 is ahead of the actual turning angle of the steering wheels 20 with respect to the direction of rotation (Sl 24.8132)
), the solenoid valve 17 remains closed (8130), but
If there is a delay, the solenoid valve 17 is opened (S126).
．． 5134), and returns to 8102. Furthermore, even when the handle 1 is stopped (S122), it is checked to see if there is any deviation (8128), and if so, the solenoid valve 17 is opened (5126), and if not, it is left closed (S130).
, return to 5102.

That is, only when the rotation angle of the steering wheel 1 lags behind the actual turning angle of the steered wheels 20 in its rotation direction, the bypass line 16 is opened and the hydraulic fluid sent to the power cylinder 8 is diverted to the steering valve unit 3. By returning the oil to the oil tank 11 with a tie, the handle 1 is rotated idly and the phase shift is corrected. In addition, potentiometer 2
If the actual turning angle To of the steered wheels 20 detected in step 2 indicates that the steering wheel 20 is running straight (8107), the Ti electromagnetic valve 17 is closed regardless of the presence or absence of deviation (3136).

Next, the above-mentioned closing routine is repeated, and if the opening of the solenoid valve 17 exceeds the predetermined time 1 during the closing routine (811
2) Branches to 5114 to detect whether or not the handle 1 is rotating. If it has already rotated, proceed to 5120, and if it has stopped, go to 'if1!' Close the i-valve 17 (5116),
Flag A is set to 1 (S118) and the process returns to 5102.

Next, when proceeding from 5102 to 5110, the 7 lag Δ is 1, so the branch routine is continued by branching at Sl 10 until it is detected that the handle 1 has rotated again (Sl 14).

That is, in the phase shift correction method of this embodiment, the handle 1
The controller 23 controls the steering wheel 20 based on detection signals from the rotary encoder 19 that detects the rotation angle of the steering wheel 20 and the potentiometer 22 that detects the actual turning angle of the steering wheel 20.
The difference between the target turning angle and the actual turning angle is calculated, and only when this deviation lags behind the steered wheels 20 in the direction of rotation except when traveling straight, the solenoid valve 17 is opened to supply power to the power cylinder 8. The hydraulic oil is returned from the bypass line 16 to the A wheel tank 11 via the steering valve unit 3, and the deviation of the steered wheels 20 is corrected. Even if the rotation of the handle is stopped, normal deviation correction other than the branch routine is performed for a predetermined time T, and only when the solenoid valve 17 continues to open after the predetermined time T, the solenoid valve 1
Close 7. Therefore, if overheating of the solenoid coil SQL of the solenoid valve 17 is not a problem, the power cylinder 8 can be bypassed by opening the solenoid valve 17 as in the past, and the next deviation correction can be made immediately. 1 The opening of the magnetic valve 17 exceeds the predetermined time T and the solenoid coil S Q L
If overheating is a problem, close the 'iC1 magnetic valve 17 only when the handle 1 is stopped to maintain the twist/idle coil SQL. And even if the opening of the solenoid valve 17 exceeds the predetermined time period, as long as the handle 1 is rotating? The solenoid coil S continues to open the tRfa valve 17.
Prioritize steering over QL maintenance.

[Effects of the Invention] As described above in detail, the phase shift correction method of the present invention is effective when the opening of the solenoid valve based on the shift detection command exceeds a predetermined time and the handle is stopped. , the solenoid valve is closed to prevent the coil from overheating, and on the other hand, if it is detected that the steering wheel is traveling straight ahead from the actual steering angle, the solenoid valve is immediately closed and correction is made even if a deviation occurs. Interrupted, 317 on the handle! Since priority is given to preventing ll, it is possible to significantly improve the durability of the solenoid valve and ensure stability of the steering wheel when driving straight ahead.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing an example of a device implementing the present invention, FIG. 2 is a flowchart showing a control operation for phase shift correction n according to the present invention, and FIG. 3 is a flowchart showing a similar conventional control operation. It is. 1... Handle 3... Steering valve unit 6.7... Hydraulic line 8... Power cylinder 16... Bypass line 17... Ti solenoid valve 9... Rotary encoder 20... Steering ring

Claims (1)

[Claims] (1) By detecting the deviation between the target turning angle of the steered wheels based on the rotation of the steering wheel and the actual turning angle, and opening the solenoid valve installed in the bypass line, the hydraulic oil supplied to the power cylinder is bypassed. In the phase shift correction method for a fully hydraulic power steering device that corrects the above shift using A method for correcting a phase shift in a fully hydraulic power steering device that commands interruption.