JPH0418941Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention detects deviations from the normal state of the correspondence between the steering wheel steering angle and the actual steering angle of the wheels, that is, the state of the steering actuator, in a fully hydraulic power steering system. The present invention relates to a correction device for correcting.

Fully hydraulic power steering systems have been known that eliminate the need for a mechanical link between the steering wheel and the actuator. This caused a deviation in the actual steering angle, making it practically impossible to use it as it was except for special vehicles. Therefore, it is conceivable to add and use a device for correcting the above-mentioned deviation, but depending on the correction method, the entire structure becomes complicated and expensive, which is impractical.

Therefore, the present invention detects the deviation of the correspondence relationship between the handle position and the actuator position from the normal state using, for example, two switch means, and based on this, the deviation is detected through a simple control means. It is an object of the present invention to provide a deviation correction device that controls, for example, an actuator so as to eliminate the above deviation.

An embodiment of the present invention will be described below with reference to the drawings. As the steering shaft 2 is rotated by the steering operation of the handle 1, the directional switching valve 3 and the constant displacement hydraulic motor 4 are operated. The valve 3 is a 6-port 3-position switching valve, and one of the two ports that is open at the intermediate position in the figure is connected to the hydraulic pump 6 via the oil passage 5, and the other one is connected to the oil passage 7. It is connected to the reservoir 8 via. Two of the four ports that are closed in the intermediate position are connected to the left and right ports of the hydraulic motor 4 via oil passages 9 and 10, and the other two are connected to the oil passage 1, respectively.
1 and 12, it is connected to left and right chambers 14 and 15 of a cylinder 13, which is an actuator for front wheel steering. In the left position in the figure, the valve 3 communicates between the oil passage 5 and the oil passage 9, the oil passage 7 and the oil passage 11, and the oil passage 10 and the oil passage 12, and in the right position, the oil passage 5 and the oil passage 10,
The oil passage 7 and the oil passage 12, and the oil passage 9 and the oil passage 11 are communicated with each other.

On the other hand, the steering shaft 2 is provided with a switch 17 that is turned ON and OFF at a neutral position where the handle 1 is not turned to the right or left.
8 is provided with a switch 20 that switches ON/OFF a neutral position in which the piston portion 19 of the piston rod 18 takes the center position within the cylinder 13 in response to the zero actual steering angle state of the front wheels.

Signals from both switches 17 and 20 are sent to the control circuit 2.
1 is input. The control circuit 21 controls the solenoid valve 22 based on this input signal. The valve 22 is a 3-port 3-position switching valve, and forms part of a control means for changing the control state of the cylinder 13 by the handle 1.
In the middle position in the figure when the two solenoids 23 and 24 are demagnetized, all three ports are closed, and in the lower position when the upper solenoid 23 is energized, the ports branch out from the oil passage 10. Oil passage 2 branched from oil passage 25 and oil passage 9
6 communicate with the upper throttle 27 via the check valve 28 to form a bypass circuit, and in the upper position taken when the lower solenoid 24 is in the excited state, the oil passage 25 and the oil passage 26 communicate with the lower throttle 27 through the check valve 28. 29 through a check valve 30 to form a bypass circuit.

The manner in which the solenoid valve 22 is controlled by the control circuit 21 is as follows.

When the neutral positions of the handle 1 and the cylinder 13 are not shifted, turning the handle 1 to the left or right turns both switches 17 and 20 simultaneously OFF or ON, and in this case, the control circuit 21 switches both solenoids 23, 24 in a demagnetized state. Therefore, the valve 22 takes an intermediate position, and the oil metered by the hydraulic motor 4 enters the cylinder chambers 14 and 15 without escaping through the oil passages 25 and 26, and the control state of the cylinder 13 by the handle 1 is maintained. is kept in its normal state.

When the handle 1 is shifted to the left relative to the cylinder 13, by turning the handle 1 to the right, the switch 20 on the cylinder 13 side will turn from OFF to ON before the switch 17 on the handle 1 side when passing the neutral position. At this time, the control circuit 21 processes this signal using a simple logic circuit and uses a timer circuit to turn on the upper solenoid 23 for a certain period of time, for example, 0.5 seconds. Then, the upper aperture 27 and check valve 28
The upper bypass circuit via is made conductive. Therefore, at this time, when the handle 1 is turned to the right and the valve 3 is in the right position, oil flows in the direction of the solid arrow in the figure, but it is metered by the hydraulic motor 4 and flows into the oil passage 9. The oil discharged into the main stream is divided into a main stream and a side stream at a branch point 9a. By turning the handle 1, a hydraulic motor 4 mechanically communicated with the handle 1 rotates, drawing air from the oil passage 10 to the oil passage 9.
Since the main flow of the discharged oil is supplied to the cylinder 14, the substream is supplied to the oil passage 26, the throttle 27, the check valve 28, the solenoid valve 22, and the oil passage 25.
It is sent from the branch point 10a to the inlet side (right) port of the hydraulic motor 4 via the branch point 10a, and then enters the hydraulic motor 4 again. In other words, this produces the same effect as increasing internal leakage in the metering section,
The handle 1 is rotated to the right by a larger angle than in the normal state with respect to the amount of rightward movement of the piston portion 19 in the cylinder 13, and control is performed in a direction in which the above-mentioned leftward deviation of the handle 1 is eliminated.

On the other hand, when the handle 1 is shifted to the right relative to the cylinder 13, when the handle 1 is turned to the left, the switch 20 is switched to the switch 17 when passing the neutral position.
The control circuit 21, which was previously turned from ON to OFF and input this signal, turns on the lower solenoid 24 for a certain period of time. Then, the lower bypass circuit via the throttle 29 and the check valve 30 is made conductive, and among the oil flowing in the direction of the dashed arrow in the figure, the oil metered by the hydraulic motor 4 and discharged into the oil passage 10 is It is divided into a main stream and a side stream at the branch point 10a. By turning the handle 1, the hydraulic motor 4 mechanically connected to the handle 1 rotates, and similarly sucks oil from the oil passage 9 and pushes it out to the oil passage 10, so that the oil is discharged. Although the main stream of oil is supplied to the cylinder 15, the side stream is supplied from the branch point 9a to the inlet side of the hydraulic motor 4 ( left)
It is sent to the port and enters the hydraulic motor 4 again, so
The amount of leftward rotation of the handle 1 is larger than the amount of leftward movement of the piston portion 19 than in the normal state, and control is performed in a direction in which the deviation is similarly eliminated.

By repeating such minute corrections, the alignment of the neutral position between the handle 1 and the cylinder 13 is maintained, and the correspondence between the handle 1 and the cylinder 13 is controlled so as not to deviate from the normal state.

Note that even if the handle 1 is suddenly turned in the opposite direction after the valve 22 is opened in the upper or lower position, the check valves 28 and 30 are still in the bypass circuit.
Since it is attached, the oil will not be bypassed during reverse rotation and no problems will occur.

Also: Even if an electrical system failure occurs, if a centering spring is inserted into valve 22, valve 2
2 is returned to the intermediate position and locked there; even if the valve 22 is turned to the upper or lower position due to locking of the valve 22 or an error signal, the throttles 27 and 29 will remain in place. Therefore, even if the internal leakage becomes a little large, there is no problem with vehicle operation. Even if the oil supply runs out in the condition described above, the internal leakage will be a little large and will only cause a shift, but emergency steering will not be hindered. In the absence of
Safety is also ensured in the event of a failure.

By the way, in the above embodiment, the predetermined position for correcting deviation is the neutral position, but it is preferable to use the neutral position because the passing frequency increases and the opportunity to correct deviation increases accordingly, but the predetermined position may be any position.

As described above, according to one basic aspect of the present invention,
For example, a conventionally known all-hydraulic power steering system includes a deviation detection means consisting of a sensor, which is two switches, and a part of a control circuit, and a control consisting of a part of the control circuit and means such as a solenoid valve. Since the configuration is such that only the means are added, the misalignment correction function can be achieved with a simple structure and at a low cost.

That is, one basic aspect of the present invention is to change the control system between the handle and the actuator based on the detection of the deviation by the deviation detection means, instead of directly acting on the actuator using a separate system to correct the deviation. Since the control means is configured to change the control state of the actuator by the handle so as to correct the deviation, the above effects can be achieved.

[Brief explanation of the drawing]

The figure is an explanatory diagram of an embodiment of the present invention. Explanation of symbols of main parts, actuator...
3. Sensor...17, 20, Control means...22.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A vehicle that uses a hydraulic motor to supply oil in an amount proportional to the rotation angle of a steering wheel that rotates around a steering shaft to actuate the wheel steering actuator. In a fully hydraulic power steering system for steering a vehicle, a first sensor detects a predetermined position of a handle with respect to the steering shaft; a method of operating the actuator corresponding to a predetermined position detected by the first sensor; a second sensor that detects a predetermined position; detects a deviation between the predetermined positions based on the respective predetermined positions detected by the first and second sensors; A correction means for correcting the deviation by controlling a portion of the oil sent from the hydraulic motor to bypass through a bypass circuit to reduce the amount of oil sent to the actuator. A deviation correction device for a fully hydraulic power steering system. 2. The actuator has a cylinder portion and a piston portion movable in the cylinder portion in the actuation direction, and the predetermined position detected by the first sensor has a rotation angle of zero with respect to the steering shaft. The predetermined position, which is the neutral position of the steering wheel corresponding to the state, and which is detected by the second sensor, is a position corresponding to the state where the actual steering angle of the wheel is zero, and furthermore, the piston part is in the cylinder part. It is a neutral position that is a central position, and the control means includes: a bypass circuit branching off from each oil passage connected to the left and right ports of the hydraulic motor; an oil passage switching valve provided in the bypass circuit; connected to a second sensor;
a control circuit that detects the deviation when the piston portion passes through a central position within the cylinder portion; and when the control circuit detects the deviation, actuates the switching valve to conduct the bypass circuit. According to claim 1, the hydraulic pressure is controlled to a motor so that the handle can rotate toward a neutral position without operating the actuator. Device.