JPH0627559B2 - Solenoid valve controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention adjusts the duty ratio for a solenoid valve,
The present invention relates to a solenoid valve control device that controls a flow rate supplied to an actuator and controls the speed of the actuator.

(Prior Art) The solenoid valve of this type of device is used, for example, in the circuit shown in FIG. 3, and one solenoid valve 1 controls the operating speed when the single-acting cylinder S as an actuator is raised, and the other one Solenoid valve 2 controls the descending speed.

In this circuit diagram, the solenoid valves 1 and 2 are in the normal position. When the solenoid valves 1 and 2 are in the normal position, one solenoid valve 1 is fully opened and the other solenoid valve 2 is fully closed.

As described above, when one solenoid valve 1 is in the normal position shown and is fully opened, the discharge oil of the pump P is pilot passage 3 → orifice 4 provided in this pilot passage 3 → solenoid valve 1 fully opened → tank Tank T via passage 5
Therefore, a differential pressure is generated before and after the orifice 4.

The differential pressure thus generated acts as a pilot pressure on both ends of the unload valve 6 provided in the tank passage 5, and switches the unload valve 6 to the fully open state shown in the figure. Therefore, the total amount of oil discharged from the pump P flows into the tank T via the tank passage 5.

When the solenoid valve 1 is energized to fully close it,
Since the flow passing through the orifice 4 is blocked, no differential pressure is generated before and after that, and the pressures acting on both ends of the unload valve 6 become the same. When the pilot pressures acting on both ends of the unload valve 6 become equal in this way, the unload valve 6 is kept in the fully closed state. Therefore, the entire discharge amount of the pump P is supplied to the cylinder S via the load check valve 8 provided in the supply passage 7. When the solenoid valve 1 is continuously energized in this manner, the solenoid valve 1 continues to be in the fully closed state, so that the total amount of oil discharged from the pump P is reduced to the cylinder S.
Is supplied to.

However, the solenoid valve 1 is not energized continuously and is turned on in a short time.
When the OFF operation is repeated, each of the flow rate passing through the solenoid valve and the differential pressure generated before and after the orifice 4 becomes substantially in the middle when the solenoid valve 1 is fully opened. Therefore, the opening degree of the unload valve 6 is also controlled accordingly, and the flow rate flowing out from the tank passage 5 becomes intermediate. Thus, if the flow rate of the pump discharge oil controlled to the above intermediate value flows out to the tank T, the remaining flow rate is changed to the cylinder S.
Will be supplied to.

Then, by controlling the duty ratio, which is the ratio of the on-time to the on-off time, the flow rate flowing into the tank T, that is, the flow rate supplied to the cylinder S, can be controlled. 4 is a graph of FIG.

In the graph of FIG. 4, the duty ratio is shown on the X-axis, the speed of the cylinder S is shown on the Y-axis, and the solid line I shows the correlation value between the two.

As is clear from the graph of FIG. 4, the operating speed of the cylinder S becomes faster as the duty ratio becomes larger, and the operating speed becomes maximum when the duty ratio becomes 100%. Conversely, the smaller the duty ratio, the slower the operating speed of the cylinder S.

The other solenoid valve 2 controls the descending speed by controlling the duty ratio and substantially functions in the same manner as the solenoid valve 1.

The operating speed of the cylinder S is controlled as described above, but the control is required in the following cases.

For example, it is a case where accurate stop position control is required while maintaining the cylinder S at a sufficient operating speed. In such a case, it is necessary to operate the cylinder S up to a position near the stop position and slowly operate near the stop position, so that the speed control described above is necessary.

As is apparent from FIG. 4, this conventional device adopts a control mode in which the operating speed of the cylinder S becomes constant at a predetermined duty ratio.

(Problems to be Solved by the Present Invention) As described above, in the conventional device, when various conditions such as the viscosity of hydraulic fluid or the load on the cylinder change, the target speed of the device is reduced even if the duty ratio is constant. However, the actual speed of the cylinder S changes. An example of this situation is the curve of the broken line I ₁ or I ₂ in FIG.

That is, even if the duty ratio is constant as shown in FIG. 4, the curve I ₁ has a higher speed than the target curve I. On the contrary, the speed of the curve I ₂ is slower than that of the target curve I.

The fluctuation range with respect to the target curve I is shown by the arrow H in FIG.
It will be very large, as shown in.

In other words, in the conventional device, the duty ratio for obtaining a predetermined speed was always constant, so if the viscosity of the hydraulic oil or the load on the cylinder changes, the target speed will change significantly, and for example, an accurate stop position There was a problem that it could not be controlled.

An object of the present invention is to reduce the fluctuation range of the actual speed with respect to the target speed by detecting the actual operating condition of the actuator and changing the duty ratio according to the detected value.

(Means for Solving Problems) In order to achieve the above object, the present invention is configured as follows.

That is, a current position detector that detects the actual operating position of the actuator in a solenoid valve control device that controls the supply flow rate to the actuator by adjusting the duty ratio with respect to the solenoid valve and controls the speed of the actuator. , A target position setter for setting the target position of the actuator, a calculation circuit for calculating the deviation between the current position detector and the target position setter, a speed detection circuit for detecting the speed of the actuator, and this calculation circuit A drive circuit for controlling the duty ratio with respect to the solenoid valve in accordance with the output signal of and the output signal of the speed detection circuit, and
This drive circuit is characterized in that a setting unit for storing a feedback gain for changing the duty ratio is provided in accordance with an output signal from the speed detection circuit.

(Operation of the present invention) Since the present invention is configured as described above, the operating speed of the actuator is fed back, and the duty ratio is changed according to the actual operating condition along the feedback gain stored in the setting unit. Let

(Effect of the present invention) According to the device of the present invention, the duty ratio is changed according to the actual operating condition of the actuator, so that various conditions such as the viscosity of hydraulic oil or the load of the actuator are changed. However, the fluctuation range of the actual speed with respect to the target speed becomes small. In this way, the fluctuation range of the actual speed with respect to the target speed can be reduced, so that the position control and the like can be performed accurately.

(Embodiment of the present invention) The embodiment shown in FIGS. 1 and 2 includes a current position detector a for detecting the actual position of the cylinder S, and a target position setter b for setting the target position of the cylinder S. And outputs the output signals of both of them to the arithmetic circuit c.

The calculation circuit c calculates the deviation between the actual position of the cylinder S and the target position and inputs the output signal as the calculation result to the drive circuit d. The drive circuit d is configured as follows. There is.

That is, the drive circuit d includes a dead zone comparison unit 11 that determines whether the output signal from the arithmetic circuit c is a dead zone signal,
And a high-speed signal determination section 12 for determining whether the signal is a slow speed signal or a high speed signal.

The dead zone comparison unit 11 does not operate when the output signal of the arithmetic circuit c is a dead zone signal or a high speed range signal. Then, when the output signal is a low speed region signal other than the dead band signal and the high speed region signal, the low speed setting unit 13 for controlling the duty ratio at the low speed is operated. The output signal from the low speed setting unit 13 is input to the solenoid valve 1 via the amplifying unit e,
Make it work.

Therefore, the solenoid valve 1 is energized intermittently according to the duty ratio set by the low speed setting unit 13, and
The speed control is performed according to the duty ratio.

The speed detection circuit f differentiates the output signal from the current position detector a to calculate the actual speed of the cylinder S each time, and at the same time outputs the speed signal to the low speed setting unit.
I'm trying to give feedback to 13.

Further, the velocity feedback gain stored in the low speed setting unit 13 is inclined downward to the right as shown by a straight line G in FIG.

Therefore, when the characteristic of the speed change of the cylinder S changes the curves I, I ₁ , and I ₂ , the duty ratio is changed. The inclination of the straight line G is set in advance so as to be an optimal inclination in consideration of various conditions.

Further, the high-speed signal determination unit 12 determines when the output signal from the calculation unit c is a high-speed region signal and operates the high-speed setting unit 14. When the high speed setting unit 14 operates in this way, the output signal thereof is input to the solenoid valve 1 via the amplification unit e, and the solenoid valve 1 is continuously energized. That is, the actuator is operated at high speed.

The operation of this embodiment will be described below.

The output signal from the current position detector a and the target position setter b
The deviation is calculated by the calculation circuit c in accordance with the output signal from, and the deviation is input to the dead zone comparing section 11 and the high speed signal judging section 12. Then, when the deviation is zero or close thereto, that is, when a signal indicating that it is in the dead zone is input to the dead zone comparison unit 11, the solenoid S is not operated and the cylinder S is kept stopped.

When the deviation reaches a low speed signal range in which the deviation is slightly larger than near zero, the solenoid valve 1 is controlled according to the duty ratio stored in the low speed setting unit 13, and the speed of the cylinder S is controlled according to the control. Is also controlled. Moreover, the cylinder S
Is operating, the speed is detected by the speed detection circuit f and is fed back to the low speed setting unit 13.

When the speed signal is fed back from the speed detection circuit f in this way, the duty ratio is changed according to the feedback gain stored in the low speed setting unit 13.

Therefore, the operating speed of the cylinder S cannot maintain the target characteristic I due to various conditions such as the viscosity of the hydraulic oil or the load on the cylinder S, and the characteristic I ₁ or
_{Even if} it changes to ₂ , the duty ratio is corrected according to the speed feedback gain shown by the straight line G,
The cylinder S operates in the range close to the target speed.

Then, as described above, the range of fluctuation between the target speed and the actual speed becomes extremely small as shown by arrow J in FIG.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention.
FIG. 3 is a block diagram showing an electric circuit, FIG. 2 is a graph showing the relationship between duty ratio and actuator speed, and FIG. 3 is a circuit diagram showing an example of use of a solenoid valve which is a control target of the present invention. FIG. 4 shows a conventional control mode and is a graph corresponding to FIG. S ... Cylinder as an actuator, 1, 2 ... Solenoid valve, a ... Current position detector, b ... Target position setter,
c ... arithmetic circuit, d ... drive circuit, f ... speed detection circuit.

Claims (1)

[Claims] 1. A duty ratio for a solenoid valve is controlled,
In a solenoid valve control device that controls the flow rate supplied to the actuator and controls the speed of the actuator, a current position detector that detects the actual operating position of the actuator, and a target position setting that sets the target position of the actuator A calculation circuit for calculating the deviation between the current position detector and the target position setting device, a speed detection circuit for detecting the speed of the actuator, and an output signal of the calculation circuit and an output signal of the speed detection circuit. And a drive circuit for controlling the duty ratio with respect to the solenoid valve, and the drive circuit is set to store a feedback gain for changing the duty ratio according to an output signal from the speed detection circuit. A control device for a solenoid valve, which is provided with a section.