JPH0754807A - Control device for hydraulic proportional control valve - Google Patents

Abstract

PURPOSE:To apply a dither voltage to a proportional valve to realize smooth operation of the valve while preventing abnormal sound generation and vibration of a device due to application of the dither voltage and provide smooth and quiet control. CONSTITUTION:In a control device of a hydraulic proportional control valve 11 wherein solenoid valves 6, 7, 13, 14 are provided upstream from the hydraulic proportional control valve 11, a cylinder 1b is driven through controlling the solenoid valves 6, 7, 13, 14, and a driving speed of the cylinder 1b is controlled through controlling an opening degree of the hydraulic proportional control valve 11, a dither voltage is applied to the hydraulic proportional control valve 11 from the time immediately before or simultaneous with a valve opening degree change of the hydraulic proportional control valve 11 to the time immediately after or simultaneous with arrival at a specified valve opening degree including closing thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a hydraulic proportional control valve used in a hydraulic device having a relatively small capacity as a hydraulic operating device for operating a beauty chair and a medical device (dental chair, operating table, etc.). Regarding the device.

[0002]

2. Description of the Related Art In recent years, a hydraulic proportional control valve (hereinafter simply referred to as a proportional valve) has been used to prevent the occurrence of an oil hammer when the hairdressing and beauty chair and medical equipment are stopped and to control the flow rate. It became so. And when this proportional valve is used, in order to prevent sticking, the proportional valve is always operated (standby)
A dither voltage was applied and the valve rod was in a dynamic friction state.

[0003]

If a dither voltage is constantly applied to the proportional valve to cause the valve rod to vibrate slightly, pulsating pressure is often induced in the hydraulic system, which causes abnormal noise and the device vibrates. Occasionally, this preventive measure has been desired.

The present invention is intended to solve the above-mentioned problems, and its purpose is to apply a dither voltage to a proportional valve so as to realize smooth valve operation while applying the dither voltage. An object of the present invention is to provide a control device for a hydraulic proportional control valve that prevents generation of abnormal noise and vibration of the device and that is smooth and quiet.

[0005]

A control device for a hydraulic proportional control valve according to the present invention is intended to achieve the above-mentioned object. The means is to provide an electromagnetic valve on the upstream side of the hydraulic proportional control valve. A control device for a hydraulic proportional control valve, which controls a valve to drive a cylinder, and controls an opening of the hydraulic proportional control valve to control a driving time of the cylinder. The dither-on signal is applied to the hydraulic proportional control valve immediately before or at the same time as the opening change, or immediately after or at the same time as reaching the predetermined valve opening including closing.

[0007]

In the hydraulic proportional control valve control device of the present invention configured as described above, the dither-on signal is sent to the hydraulic proportional control valve for a certain period of time from the beginning of the opening change of the hydraulic proportional control valve to the end of the opening change. By applying the dither-on signal, the cylinder is gently driven so as not to give a shock, and the supply of the dither-on signal is stopped after the certain period of time. Vibration can be prevented and the cylinder can be operated smoothly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below of a case in which a control device for a hydraulic proportional control valve according to the present invention is applied to elevating a hairdressing and cosmetic chair and raising and lowering a backrest. In FIG. 1, 1 is a hairdressing and beauty chair, 1a is a base of the chair 1, 1b is a lifting cylinder for a seat 1c, and the ram 1d is projected and retracted to move the seat 1c up and down relative to the base 1a. It is a thing.

1e is a backrest which is attached to the seat 1c of the chair 1 so as to be able to be raised and lowered, and 1f is a raising cylinder which is attached between the seat 1c and the backrest 1e, and a ram 1g is projected.・ Back to back 1d
Is tilted up and down with respect to the seat portion 1c. In addition, 1h is a spring for always applying a moment in the tilt direction to the backrest 1d.

Reference numeral 2 is an oil tank, 3 is a suction pipe having one end opened to the oil tank 2, and the other end is a motor pump 4
It is connected to the. One end of the supply pipe 5 is connected to the outlet side of the motor pump 4, and the other end of the supply pipe 5 is connected to the branch 5
It is connected to the supply pipes 5b and 5c which branch into two at a and reach the lifting cylinder 1b and the tilting cylinder 1f. The supply pipes 5b and 5c have a space between the branch 5a and the lifting cylinder 1b and a space between the branch 5a and the tilting cylinder 1b.
Solenoid valves for hydraulic distribution 6, 7 and check valves 8, 9 with f
Are connected in series.

Reference numeral 10 is an oil discharge pipe having one end opened to the oil tank 2, and the other end is a hydraulic proportional control valve 11 (hereinafter,
Simply called proportional valve). This proportional valve 11
One end of the discharge pipe 12 is connected to the inlet side of the exhaust pipe 12, and the other end of the discharge pipe 12 is also branched so that the motor pump 4
It is connected to the bypass discharge pipe 12c passing through the bypass pipe 5d connected to the discharge pipe 5 on the outlet side and the outlet side of the hydraulic pressure distribution solenoid valves 6 and 7.

Then, return oil solenoid valves 13 and 14 and check valves 15 and 16 are provided in the discharge pipes 12a and 12b connected to the outlet sides of the hydraulic pressure distribution solenoid valves 6 and 7, and the bypass pipe 5d is also provided. The bypass solenoid valve 17 and the check valve 18 are connected as a gate between the bypass pipe 12c and the bypass pipe 12c.

Next, the proportional valve 1 in the hydraulic circuit described above.
An electric circuit for controlling 1 will be described with reference to FIG. Although FIG. 2 shows a circuit for raising and lowering the seat portion 1b, the circuit for raising and lowering the backrest 1e is also the same, so only the raising and lowering of the seat portion 1b will be described. Reference numeral 21 is a raising / lowering operation switch for raising and lowering the seat 1b provided on the chair 1.

Numeral 22 sends an ON signal for a fixed time at the same time as or slightly later when the operation switch 21 is operated, and at the same time or slightly after the operation of the operation switch 21 is stopped, an ON signal is sent for a fixed time. A timing control circuit for sending an ON signal to a proportional valve control voltage generating circuit 23, which will be described later, is shown in detail in FIG.

Reference numeral 23 is a proportional valve control voltage generating circuit for generating a signal having a specific waveform in accordance with the signal from the timing control circuit 22, the details of which are shown in FIG. 24 is a square wave oscillating circuit for generating a square wave of high frequency (for example, 100 Hz), 25 is a switch which is turned on / off by a dither-on signal from the timing control circuit 22, and 26 is a signal from the proportional valve control voltage generating circuit 23. It is an adder circuit that adds the signals from the square wave oscillator circuit 24.

Reference numeral 27 is a DC power source, and 28 is a voltage control circuit, which cannot drive the proportional valve 11 in FIG. 1 because the output current from the adder circuit 26 is small, so that the DC power source is used to obtain a large current value. It is provided together with 27.

Next, details of the timing control circuit 22 will be described with reference to FIG. The timing control circuit 22 includes six one-shot multivibrators 22a to 22f (hereinafter simply referred to as multivibrator), four OR circuits 22g to 22j, one NOR circuit 22k, one AND circuit 22l and one. And an inverter circuit 22m.

The input of the timing control circuit 22 is connected to the raising operation switch 21a of the operation switch 21 of FIG. 2 described above, and the dither-on signal is input to the operation switch 21 of FIG.
Connected to the switch 25, and further four output terminals S
Signals from _{1 to} S ₄ are proportional valve control voltage generation circuit 2 in FIG.
3 switches S _{1 to} S ₄ .

Next, details of the proportional valve control voltage generating circuit 23 will be described with reference to FIG. This proportional valve control voltage generation circuit 2
3 denotes the output terminals S ₁ to S ₁ of the timing control circuit 22 described above.
Switch S for turning on and off by the output signal from the S _{4
1 to} S ₄ , variable resistors R _{1 to} R ₃ to which one ends of the switches S _{1 to} S ₄ are connected, and an integrating circuit 23a by an operational amplifier
It is composed of

The operation of the timing control circuit 22 shown in FIG. 3 will be described with reference to the timing chart of FIG. When the raising operation switch 21a is operated, the input end of the multivibrator 22a becomes a negative voltage, so that the output from the multivibrator 22a becomes high level. As a result, the dither-on signal is output via the OR circuits 22g and 22h.

On the other hand, when the raising operation switch 21a is off, one terminal of the AND circuit 22l is at a high level and a low level signal is input to the NOR circuit 22k. A high level signal is input to the other terminal of the
The signal for closing switch S ₄ via 2j remains high.

When the multivibrator 22a is turned off after a preset time, the AND circuit 22
Since the output from l is low level and the output of the OR circuit 22j is also low level, the output to the switch S ₄ is low level, and the output from the OR circuit 22j is low level and is inverted by the inverter circuit 22m. Then, the output for closing the switch S ₃ becomes high level.

When the multivibrator 22a is turned off, the output from the multivibrator 22b becomes high level, so that the output for closing the switch S ₁ becomes high level and the OR circuits 22g and 22h.
The dither-on signal is continuously transmitted via.

Thereafter, in the same manner, the multivibrator 2
When 2b is turned off, the output to the switch S ₁ becomes low level, and the output of the multivibrator 22c becomes high level, so that the dither-on signal is sent out via the OR circuits 22g and 22h. Therefore, the dither-on signal is output until the signal from the multivibrator 22c is turned off after the signal is output from the multivibrator 22a. And the multi-vibrator 22c
When is turned off after a certain time, the dither-on signal also stops.

Next, when the raising operation switch 21a is turned off, the input terminal of the multivibrator 22d becomes a positive voltage, so that the multivibrator 22d outputs a high level signal. Therefore, the OR circuits 22g, 2
Dither-on signal is output via 2h

When the output of the multivibrator 22d becomes low level after a certain period of time, the output of the multivibrator 22e becomes high level and the output to the switch S ₂ becomes high level. Further, the OR circuits 22i, 22
The dither-on signal is continuously output via h. Further, when the output of the multivibrator 22e becomes low level after a fixed time, the output to the switch S ₂ becomes low level.

Further, since the output of the multivibrator 22e is at a high level, one input end of the NOR circuit 22k is at a high level, and thus the AND circuit 22l.
The output of a low level, the one input terminal is at a low level of the OR circuit 22j, and the switch S ₄ the other input terminal from the output of the multivibrator 22a is at a low level, the output is at a low level Output goes to low level.

When the multivibrator 22e becomes low level after a fixed time, the multivibrator 22e
When f becomes a high level and the multivibrator 22f becomes a low level after a fixed time, the dither-on signal becomes a low level and all the operations are completed.

The operation when each of the switches S _{1 to} S ₄ of the proportional valve control voltage generating circuit 23 shown in FIG. 4 is controlled by the output from the timing control circuit 22 performing such an operation will be described.

This circuit is an integrating circuit by the operational amplifier 23a. When the switch S ₄ is in the ON state, the capacitor C is short-circuited and the output has the same voltage as the + input terminal.
Is the voltage of this + input terminal 0V by the switch S ₃ ,
Switch to a certain set value determined by the variable resistor R ₃ . Also, when the switch S ₄ is off, the switch S ₁
Alternatively, when S ₂ is in the ON state, the capacitor C is charged or discharged with the respective set voltages. The variable resistors R _{1 to} R ₃ determine whether to charge or discharge.
It depends on the setting of.

In FIG. 5 described above, the switch S ₃ is off and the switch S ₄ is on during the periods a and e, so that the output of the integrating circuit 23a is 0V. In the next period b, the switch S ₃ is turned on, so that the output of the integrating circuit 23a sharply rises to the set value determined by the variable resistor R ₃ and then the switch S ₃ is turned on.
_{Since 1} is on, it is gradually discharged.

In the next period c, the switches S ₁ , S
_{Since 2} is turned off, the output of the integrating circuit 23a holds the voltage charged in the capacitor C. Since the switch S ₂ is turned on in the next period d, the output of the integrating circuit 23a is gradually charged, and the switch S ₃ is turned off and the switch S ₄ is turned on in the next period e. The output of the integrating circuit 23a suddenly becomes 0V.

The operation of the hydraulic circuit of FIG. 1 and the block diagram of FIG. 2 will be described below with reference to the timing chart of FIG. When raising the seat portion 1c of the chair 1, the raising operation switch 21a of the raising / lowering operation switch 21 is operated. When the raising operation switch 21a is turned on, the motor pump is operated at the same time or with some delay, and the bypass solenoid valve 18 is opened to recirculate the amount of oil discharged from the motor pump 4 to the tank. Also, the hydraulic distribution solenoid valve 8 is opened.

On the other hand, when the raising operation switch 21a is turned on, the timing control circuit 22 operates as described above and applies the dither-on signal to the switch 25, so that the square wave from the square wave oscillation circuit 24 causes the switch 25 to operate. It is output to the adder circuit 26 via. In addition, the output of the timing control circuit 22 causes the proportional valve control voltage generation circuit 23 to generate a signal having the above-mentioned waveform, and the addition circuit 2
6 is output. Therefore, a signal as indicated by reference numeral 26 in FIG. 6 is output from the adder circuit 26.

The output from the adder circuit 26 is the DC power supply 2
7 and the voltage control circuit 28 current-amplifies the proportional valve 1
Since it is applied to 1, the proportional valve 11 is rapidly opened and then gradually closed in the closing direction. At this time, the proportional valve 11
Is controlled in the closing direction as a whole while vibrating finely by a signal from the square wave generating circuit 24.

The pressure oil from the motor pump 4 is gradually supplied to the elevating cylinder 1b, the shock at the time of ascending and starting is alleviated, and the proportional valve 11 is provided while the chair is ascending.
Since the dither-on signal to is not output, it is possible to realize a quiet chair lift.

When the operation of the raising operation switch 21a is stopped and turned off while the chair 1 is being raised, the dither-on signal is output again and the output from the proportional valve control voltage generating circuit 23 gradually rises. Since the pressurized oil from the motor pump 4 is discharged from the proportional valve 11 via the bypass solenoid valve 17, it is possible to prevent a shock due to the sudden stop of the chair 1.

Next, the timing control circuit 22 'connected to the lowering operation switch 21b of FIG. 7 will be described.
The circuit 22 'and the the rise operation connected timing control circuit 22 and differences points to the switch 21a, except the voltage output to the switch S ₃ is 0V is the same.

The operation is substantially the same as the above description, but since the switch S ₃ is always 0V,
When the output from the proportional valve control voltage generation circuit 23 in FIG. 4 is indicated by the waveform 23 in FIG. 8 and the down operation switch 21b is operated to be in the ON state, the voltage gradually rises, and then is maintained at a constant voltage. In addition, the lowering operation switch 21
When b is turned off, the voltage gradually decreases to 0V.

Next, the lowering operation of the seat portion 1c of the chair 1 will be described with reference to FIG.
Will be described together with the timing chart of FIG. When the lowering operation switch 21b is operated, the return oil solenoid valve 13 is opened, the proportional valve control voltage generation circuit 23 outputs the output 23, and the timing control circuit 2 is output.
Since the dither-on signal is output from 2 ′, the output of the reference numeral 26 in FIG. 8 is sent to the proportional valve 11 from the adding circuit 26.

As a result, the proportional valve 11 is gradually opened, so that the chair 1 gradually starts descending due to the weight of the chair 1 and the person sitting on the chair, and after a certain time, descends at a constant speed. . Therefore, the shock at the time of starting the lowering of the seat portion 1c is small.

Then, when the descending operation switch 21b is turned off, the adder circuit 2 on which the dither-on signal is superimposed is added.
Since the signal from 6 is output to the proportional valve 11, the proportional valve 11 is gradually closed and finally closed. Proportional valve 1
After 1 is closed, the return oil solenoid valve 13 is closed and the descent is stopped. Therefore, the shock when the descent is stopped is reduced.

In the above-mentioned embodiment, the lifting and lowering of the seat portion 1c of the hairdressing and beauty chair 1 is explained, but the raising and lowering of the backrest 1e is the same as the above-mentioned operation. Furthermore, hairdressing chair 1
The present invention is not limited to the above control, but can be effectively applied to operating tables, automobiles, ships, general industrial equipment, and the like, particularly where quietness is required. It is needless to say that these controls can be performed by a microcomputer in addition to the discrete circuit described above.

[0044]

As described above, according to the present invention, in a hydraulic circuit using a hydraulic proportional control valve, hydraulic pressure is prevented from acting on the hydraulic proportional control valve to prevent hydraulic lock and to prevent hydraulic pressure. The dither-on signal is supplied only for a short time when the opening of the proportional control valve changes, and the dither-on signal is cut off after reaching the predetermined opening, so the smooth operation of the hydraulic proportional control valve and the quiet operation of the device can be achieved. It has the effect of realizing both of the characteristics.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit showing an example of a beauty salon chair using a hydraulic proportional control valve of the present invention.

FIG. 2 is an electrical block diagram for controlling the hydraulic proportional control valve of FIG.

FIG. 3 is a block diagram showing an example of a timing control circuit at the time of rising in the block diagram of the above.

FIG. 4 is a specific circuit diagram of a proportional valve control voltage generation circuit in the block diagram of FIG.

5 is a timing chart of the block diagram of FIG.

FIG. 6 is a timing chart when the block diagram of FIG. 2 rises.

FIG. 7 is a block diagram showing another example (downward side) of the timing control circuit.

8 is a timing chart at the time of descending in the block diagram of FIG.

[Explanation of symbols]

 1b Cylinder 6,7 Hydraulic distribution solenoid valve 11 Proportional valve 13,14 Return oil solenoid valve 22 Timing control circuit 23 Proportional valve control voltage generation circuit 24 Square wave oscillation circuit 26 Addition circuit

Claims (1)

[Claims] 1. A solenoid valve is provided upstream of a hydraulic proportional control valve to control the solenoid valve to drive a cylinder, and to control the opening of the hydraulic proportional control valve to control the driving speed of the cylinder. In the control device for the hydraulic proportional control valve, the hydraulic proportional control valve is controlled immediately before or at the same time as the valve opening change of the hydraulic proportional control valve, immediately after or at the same time as reaching a predetermined valve opening including closing. A control device for a hydraulic proportional control valve, characterized in that a dither voltage is applied.