JPH0310969A - Method for correcting phase dislocation of fuel hydraulic type power steering device - Google Patents

Abstract

PURPOSE:To improve steering stability at the time of traveling forward straightly by interrupting correction of any dislocation when a steering wheel torque value is lower than a preset value for indicating non-steering condition when the dislocation of a steering angle relative to a target value is detected so as to correct the dislocation through bypass of oil supplied to a power cylinder. CONSTITUTION:During driving a car, in a controller 23, a detected value of steering wheel torque by a torque sensor 18 is judged whether it is lower than a preset value indicating non-steering condition or not, in case that it is lower than the preset value, it is judged as actual non-steering condition i.e., traveling forward, off-signal is output to an electromagnetic valve 17 in a bypass circuit 16 for communication between hydraulic lines 6, 7 so as not to perform the correction of dislocation. Meantime, at the time of turning steering wherein the torque detected value exceeds the preset value, the rotational direction and the rotational angle of a steering wheel 1 are obtained through output from a encoder 19 to calculate the target angle of a steering ring 20. A dislocation angle between the target angle of and an actual angle through a potentiometer 22 is calculated to control the electromagnetic valve 17 in the direction of dissolving the dislocation angle for performing the correction of the dislocation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for correcting a phase shift in a fully hydraulic power steering device used in a battery forklift or the like, and more specifically, the present invention relates to a method for correcting a phase shift of a fully hydraulic power steering device used in a battery forklift, etc. The present invention relates to improvements in the phase shift correction method.

[Prior Art] In general, a fully hydraulic power steering device includes a steering valve unit (in which a rotary pulp and a metering device are assembled integrally) operated by a steering wheel, a power cylinder that steers a steering wheel, It consists of a series of hydraulic lines connecting a steering valve unit and a power cylinder, and hydraulically steers the steered wheels by supplying hydraulic oil in an amount proportional to the rotation angle of the steering wheel to the power cylinder via the steering valve unit. being done.

If there is a deviation in the turning angle of the steered wheels with respect to the rotation angle of the steering wheel due to leakage of hydraulic oil in the steering valve unit, the phase of the target turning angle of the steered wheels based on the rotation of the steering wheel and the actual turning angle. The phase shift is automatically corrected by detecting the shift, opening a solenoid valve provided in a bypass circuit in the hydraulic line, and idling the handle based on the bypass of the supplied hydraulic oil.

In the above-mentioned conventional phase shift correction method, as shown in the flowchart of FIG. If θ is 0, that is, if the actual steering angle of the steered wheels is too far ahead of the target steering angle, the solenoid valve is opened and the steering wheel is rotated, thereby achieving the above-mentioned result. This is to correct phase shift.

[Problems to be Solved by the Invention] However, in the fully hydraulic power steering device that performs the above-mentioned phase shift correction, the above-mentioned shift correction is always performed regardless of whether there is a conscious steering operation. In a non-steering state, that is, when the vehicle is running straight ahead with accompanying fine steering, there is a problem in that the steering wheel moves (wobbles) due to idling, and the straight running performance is extremely hindered.

The invention disclosed in Japanese Patent Application Laid-Open No. 62-241767, which is listed for reference, does not solve the problem of improving straight running performance, but it does involve turning the steering wheel slowly while steering the vehicle toward its target. If this is done, the problem is pointed out that the vehicle's running direction does not change due to the steering wheel idling based on the misalignment correction, giving the driver a feeling of discomfort when steering.As a countermeasure, the above misalignment correction is prohibited when the steering wheel rotation speed is below a set value. Discloses technology to do so. Considering that the state in which the steering wheel rotation speed is below the set value includes the state where the rotation speed is equal to zero, that is, the state in which the vehicle is traveling straight, the detected value of the steering wheel rotation speed indicates that the vehicle is in the state in which it is traveling straight. It is natural to think that the above-mentioned deviation correction should be prohibited by determining the difference. However, the steering wheel rotation speed is not necessarily proportional to the turning angle of the steered wheels, and even when driving in a substantially straight line, including fine steering, its value fluctuates wildly across the set value, and when driving straight It is extremely difficult to understand accurately.

The technical problems to be solved by the present invention are to easily and accurately determine whether the vehicle is traveling straight and to prevent the steering wheel from swinging during the straight travel to stabilize the vehicle when traveling.

[Means for Solving the Problems] In order to solve the above problems, the present invention detects 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 operates a solenoid valve provided in the bypass circuit. By opening the channel, the hydraulic oil supplied to the power cylinder is bypassed and the above deviation is corrected. A new configuration is adopted in which a command is given to stop misalignment correction.

[Effect] According to the steering wheel torque, the fine steering phenomenon of the steering wheel that accompanies straight-ahead driving is detected as a low torque value within an extremely stable range, and the high torque value that is detected during steering operation with the intention of turning is a set value. Because it is clearly divided based on
It is possible to accurately determine whether the vehicle is traveling straight. Therefore, if it is determined that the vehicle is traveling straight based on the detected value of the steering wheel torque, priority is given to stopping the deviation correction by closing the solenoid valve.
The steering wheel is reliably prevented from swinging when driving straight ahead.

[Example] 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, and 3 is a steering valve unit operated by the handle 1. 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. 8 and a metering device (generally called a gerotor) 5. In addition, 10 in the figure is a relief valve that maintains the pressure in the circuit at a set pressure, and 1
1 is an oil tank.

The rotary valve 4 has a throttle valve 12 in the passage connecting the tank port and the metering port, 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 port and the metering port. 8
A throttle valve 14 is installed in the passage connecting the pump boat and the tank port, and a full throttle valve 15 is installed in the passage connecting the pump boat and the tank port.
Of these throttle valves, normally the throttle valve 14 provided in the passage connecting the metering boat and the cylinder boat is set to the maximum degree of restriction. Further, the hydraulic line 6 communicating with the rod side oil chamber of the power cylinder 8 and the hydraulic line 7 communicating with the head side oil chamber are communicated with each other by a bypass circuit 16, and this bypass circuit 16 allows flow of hydraulic oil. A solenoid valve 17 for opening and closing the passage is provided. The solenoid valve 17 is a normally closed on-off valve with bidirectional passage. On the other hand, the steering shaft 1a of the handle 1
is provided with a torque sensor 18 for detecting handle torque and a rotary encoder 19 as a rotation angle detector, and the rotary encoder 19 detects incremental outputs (phase A and phase B) for determining the turning direction and the rotation angle. A reference point signal (a signal indicating the reference position of the knob) corresponding to the position of the knob 2 is output. Further, a potentiometer 22 as a turning angle detector is attached to the king pin 21 of the steered wheel 20, and outputs an actual turning angle signal of the steered wheel 20. The controller 23 includes the torque sensor 18, rotary encoder 19, and potentiometer 2.
Each detection signal from 2 is inputted, and a control signal is outputted to the electromagnetic valve 17 based on the detection signal.

The apparatus implementing the present invention is configured as described above,
When the steering wheel 1 is rotated clockwise or counterclockwise, the rotary valve 4 in the steering valve unit 3 is switched from the neutral position (b) when traveling straight to the right rotation position (a) or the left rotation position (C), and the hydraulic The hydraulic oil sent from the pump 9 via the rotary valve 4 is sent to the rod-side oil chamber or head-side oil chamber of the power cylinder 8 through the hydraulic line 6 or 7 by the metering device 5 in an amount corresponding to the rotation angle of the handle 1. The steering wheel 20 is steered to the right or left.

A phase shift correction action is performed during the steering operation, and the action will be described below with reference to the flowchart of FIG. 2.

First, a handle torque detection signal is inputted by the torque sensor 18 (5100). and controller 23
It is determined whether the detected value T of the steering wheel torque based on the detection signal is less than or equal to the set value C (5102), and if it is less than the set value, it is determined that the vehicle is in a substantially non-steering state, that is, the vehicle is traveling straight,
OF to stop deviation correction to solenoid SQL of solenoid valve 17
The F signal is output with priority (S110).

Next, if it is determined that the detected value T of the paddle exceeds the set value C, that is, it is a turning rudder state, a detection signal of the rotation direction and rotation angle of the handle 1 is inputted by the incremental output of the rotary encoder 19, and based on this detection signal, Then, the controller 23 calculates the intended turning angle of the steered wheels 20 as the target turning angle Tθ (S104). Subsequently, the actual turning angle To is detected by the potentiometer 22, and the target turning angle Tθ of the steered wheel 20 is detected by the controller 23.
The deviation angle θ between the actual cutting angle To is calculated (8106)
. If the rotation angle of the steering wheel 1 is ahead of the actual turning angle of the steering wheel 20 with respect to the rotation direction (310B>
, output an OFF signal to the solenoid SQL of the solenoid valve 17 (3110), and if there is a delay, output an ON signal to the solenoid SQL to open the solenoid valve 17 (S112).
.

In other words, the phase shift correction method of this embodiment opens the bypass circuit 16 and sends the operation to the power cylinder 8 only when the rotation angle of the steering wheel 1 lags behind the actual turning angle of the steered wheels 20 in the rotation direction. The oil is returned to the oil tank 11 through the steering valve unit 3 to correct the phase shift caused by the steering wheel 1 idling, and the detected value of the steering wheel torque is used to adjust the running state of the vehicle to straight-line driving including incidental fine steering. In other words, it distinguishes between a substantial non-steering state and a conscious turning state, that is, a steered state, and when it is determined that it is a non-steering state, priority is given to stopping deviation correction.
A major feature is that the handle is prevented from swinging.

Figure 3 shows the relationship between the running state of the vehicle and the output voltage of the torque sensor.
■ represents the steering state for turning, and unlike the discrimination based on the steering wheel rotation speed, which does not make a big difference between steering and non-steering, the steering wheel torque clearly distinguishes between the two using the set value. Since it is possible to determine with high precision whether or not the vehicle is in a non-steering state, stable straight running performance can be ensured.

[Effects of the Invention] As detailed above, the method of the present invention accurately determines the substantial non-steering state, that is, whether the vehicle is traveling straight, by detecting the steering wheel torque, and when traveling straight, it is possible to accurately determine whether there is a phase shift or not. Since priority is given to stopping the deviation correction and the steering wheel is not allowed to spin idly, it is possible to reliably improve steering stability when driving straight ahead, which has been viewed as a particular problem.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing an example of a device implementing the present invention, Fig. 2 is a flowchart showing the control operation of the phase shift correction effect according to the present invention, and Fig. 3 is a diagram showing the running state of the vehicle and the output voltage of the torque sensor. FIG. 4 is a flowchart showing a similar conventional control operation. 1... Handle 3... Steering valve unit 6.7... Hydraulic line 8... Power cylinder 16... Bypass circuit 17... Solenoid valve 18... Torque sensor 19... Rotary encoder 20... Steering wheel

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 circuit, the hydraulic oil supplied to the power cylinder is bypassed. In the phase shift correction method for a fully hydraulic power steering device, in which the above shift is corrected by using the steering wheel, when the detected value of the steering wheel torque is equal to or less than the set value indicating that the steering is not in a substantially non-steering state, the above shift correction is performed. A phase shift correction method for a fully hydraulic power steering device that commands the interruption of