JPS62251505A - Controller of solenoid proportion valve - Google Patents

Abstract

PURPOSE:To prevent a solenoid proportion valve from making change-over action when a circuit voltage is greatly reduced by generating voltage identical to the neutral point voltage as the output voltage of a delay circuit when the neutral point voltage is reduced below the specified value. CONSTITUTION:The output of a neutral point voltage circuit 14 is sent to a neutral point voltage discriminating circuit 20 which generates a voltage compensating signal when it is detected that the neutral point voltage is below the specified value. The output of the neutral point voltage discriminating circuit 20 is generated as the output of the delay circuit 11 to a quickly charging circuit 21 which generates the neutral point voltage of the neutral point voltage circuit 14 as it is when the neutral point voltage discriminating circuit 20 is generating the output. Since when the supply voltage is reduced and the neutral point voltage is reduced below the voltage developed in the standard state, the voltage identical to the neutral point voltage is generated without delay to the control circuit, the solenoid proportion valve is held in the neutral state so that the solenoid proportion valve may be prevented from making change- over action.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improvement in a control device for an electromagnetic proportional valve.

(Prior Art) Proportional electromagnetic valves are known in which the valve opening degree can be controlled proportionally in either the left or right direction from a neutral position with respect to an input signal.

As a control device for such an electromagnetic proportional valve, by delaying the control signal with respect to the operation signal, excessive response during operation is prevented and the operation feeling is improved.
For example, there is a control device as shown in FIG.

Reference numeral 10 denotes an operating section which outputs a signal to proportionally control the electromagnetic proportional valve 16 in any direction from its neutral state. 11 is a delay circuit that delays the change in the input signal from the operating unit 10 at a predetermined ratio; 12 is a control circuit; and a neutral point voltage circuit 14 that outputs the signal from the delay circuit 11 and a neutral point voltage. A control signal corresponding to the signal is output in the following manner.

When the power supply circuit 13 is turned on, a predetermined normal operating voltage acts within the circuit, and at the neutral position of the operating section 10, an intermediate voltage between the maximum and minimum voltages in the re-operation direction is generated. When the intermediate voltage at this neutral position, that is, the neutral point voltage, is not input to the control circuit 12 via the delay circuit 11, the neutral point voltage is set based on the output of the power supply circuit 13 in order to maintain the electromagnetic proportional valve 16 in the neutral state. Voltage circuit 14
outputs the same voltage as the voltage at the neutral position, and when the input signal via the delay circuit 11 is equal to the voltage from the neutral point voltage circuit 14, the control circuit 12 outputs the same voltage as the voltage at the neutral position. It is determined that it is in a neutral state, and both solenoids 5QL1 and 5QL2 are kept in a non-energized state. Note that the output voltage of the neutral point voltage circuit 14 is set to correspond to 1/2 of the normal operating voltage.

On the other hand, if the input signal is lower or higher than the neutral point voltage, the control circuit 12 pulse-width modulates the input signal and outputs a pulse signal according to the input to the drive circuit 15 to drive Based on this, the circuit 15 connects the electromagnetic proportional valve 16
A driving current is applied to the solenoid 5QL1 or 5OL2, whereby the current proportional valve 16 switches to the left or right according to the input signal from the operating section 10, and the valve opening is proportional to the magnitude of the input signal. It is operated as follows.

The reason why the neutral point voltage is compared is that the signal voltage from the operation unit 10 changes up and down with the neutral point voltage as a boundary.
The electromagnetic proportional valve 16, which is operated in both directions in this way,
When a predetermined signal at the neutral position is output, the control circuit 12 connects the signal from the delay circuit 11 and the voltage from the neutral point voltage circuit 14 to prevent switching to either the left or right. I'm comparing.

Furthermore, the reason why the delay circuit 11 is provided with a delay function for signal changes is to prevent sudden changes in the opening degree of the electromagnetic proportional valve 16 due to an excessive response when a control operation is suddenly performed on the operating section 10. For example, solenoid proportional valve 1
This is to stabilize the operation of the hydraulic cylinder controlled via 6.

(Problem to be Solved by the Invention) However, in such a control device, if the power source is shared for multiple purposes as a power circuit, it may be necessary to use the power source when other electrical loads suddenly increase, or when the battery installed in the vehicle is used as the power source. When there is a significant voltage drop that occurs when the starter motor is rotated when the engine is started, the neutral point voltage may drop below the specified value.Normally, the circuit voltage is set to the normal operating voltage with some margin. It is set somewhat higher than the normal operating voltage, so even if the electrical load changes slightly, it will not fall below the normal operating voltage.In this case, the neutral point voltage, which is set to 1/2 of the normal operating voltage, will change. However, this phenomenon occurs when the electrical load increases significantly.

Then, even though the operation unit 10 is in the neutral state, the input signal is delayed by the delay circuit 11, so the moment the neutral point voltage drops below the normal voltage, the input signal is input from the delay circuit 11 to the control circuit 12. A difference occurs between the neutral position signal and the neutral point voltage of the neutral point voltage circuit 14,
As a result, the control circuit 12 determines that the signal from the operating section 10 is not in the neutral state, and operates the electromagnetic proportional valve 16 in response to the decreased signal from the delay circuit 11 as if the operating section 10 had been operated from the neutral state. If the drive current is allowed to flow, a problem arises in that the electromagnetic proportional valve 16 performs a switching operation even though it does not actually output a switching operation signal.

The present invention is intended to solve this problem by making the output of the delay circuit and the output of the neutral point voltage circuit the same regardless of the operation signal of the operating unit when the neutral point voltage decreases. , the drive current does not flow through the electromagnetic proportional valve.

(Means for Solving the Problems) Therefore, the present invention provides an operation section that outputs a signal whose voltage changes vertically with respect to the neutral position, a delay circuit that delays and outputs this signal, and a neutral point voltage. A neutral point voltage circuit that outputs a neutral point voltage circuit, a control circuit that compares the output of the delay circuit and the neutral point output and outputs a signal according to the output of the delay circuit when there is a voltage difference, and an electromagnetic proportional In a control device for an electromagnetic proportional valve, which is equipped with a drive circuit that selectively supplies current to the left and right solenoids of the valve in accordance with the output, a determination circuit detects when the neutral point voltage has fallen below the regular specified voltage. and a quick charging circuit that outputs the same value as the reduced voltage as the output voltage of the delay circuit while the neutral point voltage is lower than the specified value.

Therefore, when the power supply voltage drops below the normal operating voltage and the neutral point voltage drops below the normal state, the neutral voltage input from the operation unit to the delay circuit decreases, causing the output of the delay circuit to reach the specified level. However, instead of this output, the quick charging circuit outputs a voltage with no delay that is the same as the neutral point voltage to the control circuit, so the control circuit determines that the operating part is in the neutral position. Keep the solenoid proportional valve in a neutral state.

This prevents the electromagnetic proportional valve from switching when the circuit voltage significantly decreases.

(Example) Examples of the present invention will be described below based on the drawings.

The characteristic parts of the present invention are the parts indicated by numerals 20 and 21 in FIG.
A neutral point voltage discrimination circuit 21 detects when the voltage is lower than 1/2 of the normal operating voltage of the circuit and outputs a voltage compensation signal during this period, and when there is an output from this neutral point voltage discrimination circuit 20, This is a quick charging circuit that outputs the neutral point voltage of the neutral point voltage circuit 14 as it is to the control circuit 12 as the output of the delay circuit 11.

Specifically, the neutral point voltage determination circuit 20 is configured, for example, as shown in FIG. The operational amplifier OP compares the potential at point b) with the potential at point (h), and while the potential at point (a) is higher than the potential at point (h), the operational amplifier OP outputs a high-level compensation signal. Note that Dl is a diode.

The circuit voltage is the output of the neutral point voltage circuit 14 (1/2 of the normal operating voltage), but the adjusted output of the power supply circuit 13 (normal operating voltage Vce) may also be used.

Figure 4 shows changes in the power supply voltage (not the normal operating voltage, but a voltage that fluctuates depending on the circuit load, and corresponds to (a) in Figure 2), the voltages at points (a) and (b), and normal operation in response to this change. The relationship between the voltage Vce and the voltage compensation signal that is the output of the operational amplifier OP is shown.

The voltage at point (a) is a predetermined level lower than Vcc,
The voltage at point (b) follows the voltage at point (a), but when the neutral point voltage recovers to its normal state, the voltage at point (a) exceeds the voltage at point (a) and matches Vcc due to charging saturation of capacitor C1. Therefore, while the neutral point voltage is lower than the normal value, the operational amplifier ○P outputs a high level signal, and after the voltage is restored to the normal voltage, the output is switched to low level.

Other configurations that are the same as those in Figure 5 are given the same reference numerals.
The operation will be explained in detail below with reference to FIG.

(A) to (G) in FIG. 2 show output waveforms of respective portions corresponding to those in FIG.

In this case, as shown in (a) due to the power supply function of the power supply circuit 13, the circuit voltage is maintained above the normal operating voltage even though the power supply voltage fluctuates slightly, and then the electrical The following explanation assumes that the voltage suddenly drops below the normal operating voltage due to a significant increase in load, and then gradually recovers.

The regulated output of the power supply circuit 13, i.e. the normal operating voltage (
In contrast to (b), the output (c) of the neutral point voltage circuit 14 is 172. If the output (d) of the operating unit 10 remains at the neutral position, it will match the output (c) of the neutral point voltage circuit 14. Even if the power supply voltage (A) fluctuates, this neutral point voltage maintains its normal value as long as it is higher than the normal operating voltage.

When the power supply voltage drops below the normal operating voltage, the neutral point voltage also drops from its normal state, and after the output (E) of the delay circuit 11 drops once, it tries to follow the output (D) with a time delay. .

However, during this time, the neutral point voltage discrimination circuit 20 detects a drop in the neutral point voltage and the output becomes high level, and based on this, the quick charging circuit 21 directly outputs the neutral point voltage as its output. In addition, the output (E) of the delay circuit 11 matches the output (C) of the neutral point voltage circuit 14, as shown by the solid line. Therefore, even if the neutral point voltage drops below the normal value, the signal input to the control circuit 12 (
(E) and (C) are the same, and therefore, the control circuit 12 will not erroneously output a drive signal to the electromagnetic proportional valve 16 via the drive circuit 15 unless the operating unit 10 changes from the neutral position. .

When the output (D) is changed by operating the operation unit 10 to switch the electromagnetic proportional valve 16, the output (E) from the delay circuit 11 follows with a delay, and the control circuit 12 changes the output of the neutral point voltage circuit 14. Based on the difference between
Outputs a pulse signal as shown in . In this case, the output (c) from the neutral point voltage circuit 14 does not change.

As a result, a drive pulse is output from the drive circuit 15 to the solenoid 5QL1 or 5OL2 of the electromagnetic proportional valve 16. The control circuit 12 determines which solenoid to excite depending on whether the output from the delay circuit 11 is higher or lower than the neutral point voltage.

Note that when the neutral point voltage is lower than the specified value, the neutral point voltage is directly outputted from the quick charging circuit 21 as the output of the delay circuit 11, so if you temporarily operate the operation unit 10 in this state to output the switching signal. However, switching control of the electromagnetic proportional valve 16 cannot be performed and it is held at the neutral position. This is because correct control cannot be performed even if control is performed in a state lower than the normal operating voltage.

(Effects of the Invention) As described above, according to the present invention, when the power supply voltage is lower than the normal operating voltage and the neutral point voltage is lower than the normal state, the output of the delay circuit is the same as the neutral point voltage. Since a voltage with no delay is output to the control circuit, the control circuit determines that the operating part is in the neutral position and holds the solenoid proportional valve in the neutral state, preventing the solenoid proportional valve from breaking when the circuit voltage decreases significantly. Prevents it from operating.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram showing the operating waveforms of each part, Fig. 3 is a specific circuit diagram of the neutral point voltage discrimination circuit, and Fig. 4 is its A waveform diagram showing operating waveforms, and FIG. 5 is a block circuit diagram of a conventional example. 10... Operation unit, 11... Delay circuit, 12...
- Control circuit, 13... Power supply circuit, 14... Neutral point voltage circuit, 15... Drive circuit, 16... Solenoid proportional valve,
20... Neutral point voltage discrimination circuit, 21... Rapid charging circuit.

Claims (1)

[Claims] An operation unit that outputs a signal whose voltage changes vertically with respect to the neutral position, a delay circuit that delays this signal and outputs it, a neutral point voltage circuit that outputs the neutral point voltage, and an output of the delay circuit and the neutral A control circuit that outputs a signal according to the output of the delay circuit when there is a voltage difference compared to the point output, and a current that selectively flows to the left and right solenoids of the electromagnetic proportional valve according to the output of the control circuit. In a control device for an electromagnetic proportional valve, the control device includes a determination circuit that detects when the neutral point voltage has decreased below a specified voltage, and a determination circuit that detects when the neutral point voltage is lower than the specified voltage. A control device for an electromagnetic proportional valve consisting of a quick charging circuit that outputs a value as an output voltage of a delay circuit.