JPS6349116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid valve drive device that starts controlling a current supplied to a solenoid valve that operates proportionally in accordance with a control input voltage using a current that is responsible for the spring set load of the solenoid valve.

The so-called proportional control type solenoid valve, in which the shaft lift, or valve opening, changes depending on the supplied current,
Generally, as shown in the schematic diagram of FIG. 1, for example, the lift of the valve body 3 integrated with the shaft 2 is continuously changed while maintaining a balance between the force of the spring 4 and the magnetic force generated by the current flowing through the coil 1. It is configured to control the opening degree of the inlet 6 and the outlet 5,
The relationship between current and lift is shown in Figure 2.

However, in the solenoid valve having the above-mentioned characteristics, the valve body 3 may be affected by a differential pressure of the fluid between the inlet 6 and the outlet 5, or by disturbances such as vibration.
moves (displaces). For example, even if the valve body 3 is structured to close by a spring force when no current is applied, leakage will occur. To solve this problem, if the spring set load of the solenoid valve is increased and the relationship between the coil current and the lift amount is made as shown in FIG. 3, the leakage when the valve is closed will be reduced. However, even if the current is increased from 0, the valve body 3 will not open until the current value corresponds to the set load, and the time during this time will become uncontrollable or a time delay.

In view of the above problems, the present invention sets the spring set load of the solenoid valve to a predetermined value, keeps the control current at 0 in the solenoid valve drive circuit, and instantaneously changes the control current to the predetermined value (I By increasing the current to _B ), by configuring the control to start from a predetermined current value and perform continuous current control thereafter, the valve body can remain closed until the vibration reaches a value determined by the set load when the valve is closed. The object of the present invention is to provide an electromagnetic valve drive device that can change the valve opening in an arbitrary pattern when proportionally changing the valve opening, and that has almost no response delay until the valve body opens. .

The present invention will be described below with reference to embodiments shown in FIG. 4 and below. FIG. 4 shows an embodiment of the present invention, in which 1 is a coil of a solenoid valve connected to a power supply +B, 10
is a control voltage circuit that generates a voltage waveform that controls the opening amount of the solenoid valve (ie, the current of the coil 1) in response to a switching signal from the input terminal a. In this embodiment, the switching signal is a rich/lean discrimination signal of an air-fuel ratio sensor of a known air-fuel ratio feedback control system in an engine exhaust purification system. In this control voltage circuit 10, 11 is an operational amplifier, the reference voltage is determined by resistors 12 and 13 connected to the power supply +V and earth E, and the resistor 14
and capacitor 15 constitute an integrator whose slope is determined. Reference numerals 16 and 17 are transistors, respectively, which constitute upper and lower voltage limiters of the integrator determined by resistors 18 and 19 and resistors 21 and 22, respectively. 2
Both capacitors 0 and 23 serve to absorb noise. 24 is a voltage comparator that compares the voltage determined by resistors 25 and 26 with the output of the integrator input via resistor 27. 28 is a diode, and 29 is a resistor for feeding back the output of the comparator 24 to the voltage limiter. 30 is a transistor, 31 is a resistor, and is activated by the switching signal from input terminal a.
Turn on/off. 40 is a solenoid valve drive circuit, 60
is a triangular wave oscillation circuit. 41 is a driving transistor that turns on/off the current supplied to the coil 1. 42 is a current detection resistor that detects the current flowing through the coil; 43 is an operational amplifier that amplifies the voltage across the resistor 42 by a value determined by resistors 45 and 46; 44 is an input resistor, and 47 is an operational amplifier, which together with a resistor 49 and a capacitor 50 forms an integrator. 4
8 is an input resistance. 61 is a voltage comparator, 62,
63 to 66 are resistors, and 67 is a capacitor. 5
1 is a voltage comparator that compares the integrator output and the triangular wave oscillation circuit 60 output and outputs an ON/OFF signal; 5
2 and 53 are input resistances of the comparator 51, and 54 is a base input resistance of the transistor 41. 55, 56
are a resistor and a Zener diode connected between the collector and emitter of the transistor 41, respectively, for removing the positive peak voltage when the current in the coil 1 is turned off.

Next, the operation of the above configuration will be explained. Now input terminal a
When a switching signal as shown in FIG. b stops at a certain voltage Vmin (Fig. 5, 2). At this time, the transistor 30 is ON, the non-inverting input terminal c of the comparator 24 is lower than Vmin (OV), the output of the comparator 24 is at a low level (OV), and the diode 28 is
The lower limit voltage Vmin of the integrator is determined by the resistors 21 and 22. Next, when the switching signal at the input terminal a changes from +V to 0, the transistor 30 is turned off, and the non-inverting input terminal c of the comparator 24 becomes a predetermined value V _B (>V min). At this point, the voltage Vb at the output terminal b of the integrator is Vb<V _B , and the output of the comparator 24 is at a high level (for example, +V).
Therefore, diode 28 is turned on, so the voltage
Vb tries to rise to the voltage determined by resistor 21, resistor 29, and resistor 22, but at the point when Vb≧V _B , the output of comparator 24 becomes low level, and the voltage
Vb stops increasing. However, since the switching signal at the input terminal a is OV, the integrator is operating and the output terminal b of the integrator gradually rises.
When the voltage continues to rise and exceeds the voltage determined by the resistors 18 and 19, the transistor 16 becomes conductive and the output b stops at the upper limit voltage Vmax. (See FIG. 5, FIG. 2) The above is an explanation of the operation of the control voltage circuit 10.
A voltage waveform Vb which rises or falls at a predetermined slope is obtained from the integrator output b by a switching signal from the input terminal a. Next, the operation of the electromagnetic valve drive circuit 40 that changes the valve opening, that is, the coil current depending on the control voltage Vb, will be described. When the output terminal d of the comparator 51 is at a high level as shown in FIG.
A current flows through the terminal, and the terminal voltage e of the current detection resistor 42 becomes as shown by the solid line in FIG. 6. Further, the output terminal f of the amplifier 43 is connected to the voltage e as shown by the dashed line in FIG.
It can be obtained with a constant amplification factor of . When the control voltage Vb changes as shown by the broken line in FIG. 6, the integrator 47
Using this voltage as a reference, integration is performed with a slope corresponding to the deviation from the voltage at terminal f, and a waveform as shown in FIG. 6 is obtained at the output terminal g. The comparator 51 compares this integrated output with the triangular wave output shown in FIG. 6 from the output terminal h of the triangular wave oscillation circuit 60. Such an operation is performed continuously to perform feedback control of the energization time of the current flowing through the coil 1, so that the average value of the current corresponds to the control voltage Vb.

When looking at the above-mentioned opening degree of the solenoid valve, it becomes as shown in FIG. That is, a switching signal is input from input terminal a (Fig. 7 1), and the control voltage
Integrate from V _B (Figure 7 2). The average current of the ON/OFF current flowing through the coil 1 of the solenoid valve in response to the control voltage Vb is approximately as shown in FIG. 7. Now, the relationship between the solenoid valve lift (valve opening amount) and current is shown in Figure 7 3.
The actual lift (valve opening amount) is 7th.
As shown in FIG. 4, it can be seen that there is no delay due to the spring setting load. This explanation is based on an example in which the spring set load and control current I _B are matched, but if the set load varies due to production variations, etc., the optimal value for the application may be set by slightly decreasing or slightly increasing IB. You can also respond by setting it.

Further, in the above embodiment, the transistor 16 is provided to set the upper limit voltage of the control voltage, and this is so that when the input terminal a changes from O to +V, the lift also changes immediately. In other words, in the current-lift characteristic of a solenoid valve, as the current increases, the lift amount is mechanically suppressed and becomes saturated as shown in Figure 3. By stopping the value at a predetermined value, the solenoid valve can be used in a linear region, which has the advantage of reducing response delay (delay when the lift decreases in FIG. 7).

Next, a second embodiment of the present invention is shown in FIG. In the first embodiment, as shown in FIG. 5, the control voltage _VB (corresponding to the set load) is ignored when the voltage drops and becomes effective only when the voltage rises. In the example, V _B is applied both during ascending and descending.
It is configured so that it is effective. This embodiment differs from the first embodiment described above in the following points. The collector of the transistor 36, which is turned on and off by the switching signal at the input terminal a, is connected to the resistor 2 without connecting it to the resistors 25 and 26.
9 and the connection point of diode 28. 35 is the base resistance of the transistor 36. Furthermore, the comparator 24
is connected to the inverting input of the operational amplifier 11 via a resistor 34 and a diode 32, and at the same time, a diode 33 is connected to the input terminal a. 57 is an operational amplifier. The operation of this second embodiment will be explained with reference to FIG. 9. When the switching signal at the input terminal a is +V, the output terminal b of the integrator gradually falls. Further, since the transistor 36 is on, the diode 28 is off. In this state, when the output terminal b continues to fall and becomes below the voltage determined by the resistors 25 and 26, the comparator 24 is inverted and becomes a high level (for example, +V). Current then flows through the resistor 34 and diode 32 to the integrator.
Now, if the resistor 34 is made sufficiently smaller than the resistor 14, the integrator output b will drop instantaneously, and when it reaches the voltage determined by the resistors 21 and 22, the transistor 17 will become conductive and will reach a constant value Vmin. Next, when the switching signal at input terminal a becomes zero from +V, the current to the integrator all flows to terminal a due to the diode 33 being turned on. At the same time, transistor 36 is turned off
Therefore, the output terminal j of the comparator 24 is at a high level, and the current flows through the resistor 29, the diode 28, and the resistor 22. The voltage at the contact point of the resistor 21 and the resistor 22 increases, and the integrator output voltage Vb also increases. When the voltage determined by 26 is reached, the output of the comparator 24 is inverted and becomes (+V
→O), it performs integration using the input terminal a signal and begins to rise. The following operations are similar to the first embodiment.

When opening the proportional solenoid valve from the fully closed position, control is started by increasing the control current I _B stepwise to approximately correspond to the set load of the spring of the proportional solenoid valve, and then continuously. The current is controlled to proportionally control the solenoid valve, and the current actually flowing through the coil is fed back to correct the control current, so when the valve opens, the valve body closes firmly enough with the value determined by the set load. When the valve opening degree is changed proportionally, stable and accurate current control is possible without being affected by voltage fluctuations, and there is an excellent effect that there is little response delay until the valve body opens.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a solenoid valve used in the present invention,
Fig. 2 is a characteristic diagram of a solenoid valve without a set load, which is used to explain the present invention, Fig. 3 is a characteristic diagram of a solenoid valve with a set load according to the present invention, and Fig. 4 is a characteristic diagram of a solenoid valve with a set load according to the present invention. Electrical circuit diagrams showing examples, Figures 5 and 6
7 and 7 are both waveform diagrams for explaining the operation of the first embodiment of the present invention, and FIG. 8 is a waveform diagram for explaining the operation of the first embodiment of the present invention.
FIG. 9 is a waveform diagram for explaining the operation of the second embodiment of the present invention. 1... Coil of a solenoid valve, 3... Valve body, 4... Spring, 10 and 40... A control voltage circuit and a solenoid valve drive circuit forming a solenoid valve control circuit.

Claims (1)

[Claims] 1. An electromagnetic force proportional to the value of the control current applied to the coil and a spring force acting in the opposite direction to this electromagnetic force are applied to the valve body, and the opening degree of the valve body is determined by the control current. In the proportional solenoid valve control method that controls the valve proportionally according to the value of the valve, when opening the valve body from the fully closed position, the value of the control current is set to a predetermined value approximately corresponding to the set load of the spring. Thereafter, the current actually flowing through the coil is detected, the deviation between this detected value and the value of the control current is determined, and a signal corresponding to this deviation is compared with a slope waveform signal of a predetermined period to control the control current. A proportional solenoid valve control method, comprising: creating an on/off signal corresponding to a current, and applying this on/off signal to the coil.