JP2986577B2 - Electromagnetic control valve controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic control valve control device for controlling an exciting current flowing through a solenoid of an electromagnetic control valve.

[0002]

2. Description of the Related Art Conventionally, this type of electromagnetic control valve control device has
It has a configuration described in Japanese Utility Model Laid-Open No. 58-142911. That is, an output voltage signal of a calculator for calculating a difference between a control voltage signal for setting the magnitude of the exciting current and a voltage signal generated in a current detecting resistor for detecting the exciting current flowing through the solenoid, and an output of the triangular wave oscillator. The triangular wave voltage signal is input to the comparator as a comparison signal, and a voltage pulse having a different pulse width is output from the comparator at the oscillation cycle of the triangular wave oscillator based on the magnitude relation between the two comparison signals. The solenoid is excited by turning on and off a power switching element connected in series with the solenoid. According to such a configuration, the power switching element can be energized in the saturation region by the on / off operation.
There is an advantage that heat generation of the power switching element can be reduced and power consumption can be reduced.

[0003]

However, in general, it is necessary to add dither to this type of electromagnetic control valve. That is, the exciting current of the solenoid is periodically changed so as to generate a small amplitude vibration in the valve body that is operated based on the attraction force generated in accordance with the exciting current when the solenoid is excited, thereby reducing the hysteresis. It is. According to such a configuration of the conventional example, it seems that the power switching element is turned on and off based on the cycle of the triangular wave to achieve the object.
However, in practice, the period of the triangular wave cannot be made so large for good control of the exciting current, and the back electromotive voltage induced when the power switching element is off causes the flywheel diode to be installed in parallel with the solenoid. Since the exciting current flows through the solenoid, the exciting current does not change with a sufficient amplitude only by the on / off operation of the power switching element, and a good dither effect cannot be obtained. Under such circumstances, in order to obtain a good dither effect, an oscillator for dither is separately provided, and the output of this oscillator is provided so as to be superimposed on the output side of the arithmetic unit.
Since two oscillators are required, the configuration of the electric circuit becomes complicated, and there is a problem that the electromagnetic control valve control device is enlarged.

SUMMARY OF THE INVENTION The present invention is to solve such a problem, and it is an object of the present invention to provide an electromagnetic control valve control device in which components provided so as to obtain a dither effect with one oscillator can be made small. It is.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides a power switching element for controlling on / off of a current from a power supply to a solenoid, a current detector connected in series with the solenoid and detecting an exciting current flowing through the solenoid, A flywheel diode connected in parallel to the solenoid and the current detector to supply an exciting current to the solenoid when the power switching element is turned off, and a difference between an exciting current setting signal and a smoothed output signal of the current detector. An output unit is provided, and these two signals are derived so as to obtain an output signal of the current detector corresponding to the output signal of the operation unit, and a pulse signal is output according to the magnitude relationship between the two signals, and the power switching element is turned on / off. An operable comparator is provided, and an oscillator that outputs a vibration signal of a predetermined cycle is included in the output signal of the arithmetic unit to the comparator. It is connected to the input path of the output paths or setting signals of the arithmetic unit so as to present a vibration signal to be Heather signal.

[0006]

According to the structure of the present invention, the comparator outputs a pulse signal and turns off the power switching element when the output signal of the current detector becomes larger than the output signal of the arithmetic unit. On the other hand, when it becomes smaller, the ON operation is repeated, and the output signal of the current detector follows the output signal of the amplifier. As a result, an exciting current corresponding to the setting signal can be obtained. A vibration signal serving as a dither signal from the oscillator is superimposed on the output signal of the arithmetic unit, so that the excitation current can obtain a dither action having a periodic change according to the dither signal. Therefore, one oscillator can be used for the dither signal, the number of components can be reduced, the circuit configuration can be simplified, and the electromagnetic control valve control device can be reduced in size.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 18 denotes a terminal connected to a power supply. A power transistor 12, which is a power switching element, a solenoid 13, and a detection resistor 14 for forming a current detector are connected in series between the terminal 18 and the ground. The power transistor 12 is turned on and off by the comparator 6 to control the current from the power supply to the solenoid 13, and the solenoid 13 controls the flow rate or pressure of the fluid based on the attraction force generated in accordance with the exciting current flowing through the power transistor 12. This is for operating a valve element of a current control valve. Reference numeral 15 denotes a flywheel diode connected in parallel to the solenoid 13 and the detection resistor 14 connected in series. Reference numeral 11 denotes a low-frequency oscillator, which includes a triangular wave oscillation circuit 7, an impedance conversion circuit 8, a differentiation circuit 9, and a voltage level conversion circuit 10. The oscillator 11 functions to generate a vibration signal serving as a dither signal, and a triangular wave voltage oscillating at a constant cycle and amplitude generated by a charging and discharging phenomenon of a consumper constituting the triangular wave oscillator 7 is subjected to impedance conversion in an impedance conversion circuit 8. After the response is made high in the differentiating circuit 9, the voltage level is converted in the voltage level converting circuit 10 in order to match the voltage level of the voltage waveform applied to the non-inverting terminal 5 of the comparator 6. The output wiring 11A of the oscillator 11 is connected to the inverting terminal 4 of the comparator 6. The arithmetic unit 2 has an operational amplifier 2A in which a command voltage terminal 1 for applying a command voltage for setting an exciting current flowing through the solenoid 13 is connected to a non-inverting terminal 2F via a resistor 2B. Then, a detection voltage corresponding to the exciting current of the solenoid 13 generated by the detection resistor 14 is applied to the inverting terminal 2G of the operational amplifier 2A via the feedback path 19 and the resistor 2C via the feedback path 19, and smoothes the fluctuation component of the applied voltage. And the operational amplifier 2
A outputs a difference voltage between the command voltage and the detection voltage smoothed by the capacitor 2E. This output signal is superimposed on a vibration signal from the oscillator 11 via the resistor 20 from the output wiring 2H and is connected to the inverting terminal 4 of the comparator 6. On the other hand, the non-inverting terminal 5 of the comparator 6 has a detection resistor 14
A detection voltage corresponding to the exciting current of the solenoid 13 generated in the step 13 is applied via the resistor 21 through the feedback path 19, and when the command voltage is zero [volt], the exciting current of the solenoid 13 is set to zero [ampere]. The output voltage of the zero adjuster 3 composed of a variable resistor is applied via a resistor 22.
Reference numeral 23 denotes a capacitor for giving a threshold value at the time of the inverting operation of the comparator 6.
Is connected to the base terminal of the power transistor 12. Reference numeral 17 denotes a stabilized power supply for applying a constant voltage to the oscillator 11 and the zero adjuster 3.

Next, the operation of the above configuration will be described. A predetermined command voltage is applied to the command voltage terminal 1 so that the solenoid 1
It is assumed that an exciting current is flowing through 3. At this time, the arithmetic unit 2 outputs a difference voltage between the command voltage and an average voltage of the detection voltage corresponding to the exciting current generated by the detection resistor 14 and subjected to a smoothing action by the capacitor 2E. Are input to the inverting terminal 4 of the comparator 6. Now, when the detection voltage from the detection resistor 14 input to the non-inverting terminal 5 of the comparator 6 is smaller than the voltage of the inverting terminal 4, the output voltage of the comparator 6 becomes zero [volt] in a stepwise manner. Power transistor 12
Is turned on. Since the power supply voltage is applied to the solenoid 13 in a stepwise manner according to the ON state of the power transistor 12, an exciting current that rises with a time constant based on the power supply voltage and the resistance and inductance of the solenoid 13 itself flows through the solenoid 13. With the increase of the exciting current, the detection voltage generated by the detection resistor 14 increases, and when the voltage of the non-inverting terminal 5 of the comparator 6 becomes larger than the voltage of the inverting terminal 4, the output voltage of the comparator 6 becomes positive saturation. The power transistor 12 is inverted stepwise to a voltage, and accordingly, the power transistor 12 is turned off stepwise. At this time, the solenoid 13
Since the power supply is cut off from the power supply, an exciting current that falls through a flywheel diode 15 based on a back electromotive voltage induced by the inductance of the solenoid 13 and has a predetermined time constant flows through the solenoid 13. When the exciting current decreases and the voltage of the non-inverting terminal 5 of the comparator 6 becomes smaller than the voltage of the inverting terminal 4 again, the output voltage of the comparator 6 is inverted to zero [volt] in a stepwise manner. As a result, the power transistor 12 is turned on stepwise. Since the power supply voltage is applied to the solenoid 13 in a stepwise manner according to the ON state of the power transistor, an excitation current that rises with a time constant based on the power supply voltage and the resistance and inductance of the solenoid 13 itself flows through the solenoid 13. By repeating such an operation, the detection voltage of the detection resistor 14, that is, the excitation current of the solenoid 13 follows the voltage input to the inverting terminal 5 of the comparator 6. As a result, FIG.
As shown in (1), an exciting current 31 having an average value 30 on which the triangular wave of the oscillator 11 is superimposed flows through the solenoid 13, and the exciting current changes in the cycle of the triangular wave, so that an effective dither effect is obtained. 32 is an ideal waveform of the exciting current, and a pulse waveform indicated by 33 is the power transistor 1
3 is an output voltage waveform of a comparator 6 that turns on and off the second comparator 2;
When the command voltage to the command voltage terminal 1 changes, the output voltage of the arithmetic unit 2 changes accordingly, and the cycle of the ON state and the OFF state of the power transistor 12 changes, and the exciting current of the solenoid 13 becomes a new average current. Changes to Based on this, the voltage of the inverting terminal 2G of the operational amplifier 2A changes, and the output voltage of the arithmetic unit 2 outputs a new voltage, and the solenoid 1
The excitation current of No. 3 is maintained at the new average current level. Thus, an exciting current corresponding to the command voltage to the command voltage terminal 1 is obtained.

By the way, the comparator 6 used in this embodiment is used.
When the exciting current of the solenoid 13 is controlled by the above, an exciting current corresponding to the voltage input to the inverting terminal 4 of the comparator 6 can be obtained, so that the computing unit 2 is unnecessary and the command voltage is simply input directly to the inverting terminal 4 of the comparator 6. However, there is a doubt that the excitation current can be controlled with sufficient accuracy. This is valid unless a dither signal is added to the exciting current.
However, when the dither signal is applied, the following situation occurs.

That is, when the power supply voltage is reduced, or when the resistance of the solenoid 13 is increased due to heat generation or when they are overlapped with each other, the exciting current of the solenoid 13 when the power transistor 12 is turned on when the operation unit 2 is not used is used. , The falling time constant of the exciting current when the power transistor 12 is turned off does not increase. Therefore, as shown in FIG. 3, the exciting current waveform 40 cannot follow the dither signal at the rise of the dither signal and becomes smaller than the rising gradient of the ideal exciting current waveform 41, while the ideal excitation follows the dither signal at the fall of the dither signal. Current waveform 4
An exciting current waveform such as 40 which falls at a falling slope of 1 is obtained, and the average value 43 of the exciting current 40 is smaller than the average value 42 of the ideal exciting current waveform 41. For this reason, the suction force of the solenoid 13 changes, and accurate control of the current control valve cannot be expected. In this embodiment, if the average value of the exciting current decreases, the output voltage of the arithmetic unit 2 increases in proportion to the decrease, and the input voltage of the inverting terminal 4 of the comparator 6 increases. As a result, as shown by 50 in FIG. 4, the excitation current decreases the dither amplitude, but the average value of the excitation current becomes equal to the average value 42 of the ideal excitation current. Therefore, the arithmetic unit 2 exhibits its effectiveness only when the dither signal is applied.

As described above, according to this embodiment, the power transistor can be turned on and off to reduce heat generation and power consumption, and the number of oscillators for the dither signal can be reduced to one. The electromagnetic control valve control device of (1) is obtained. By using the arithmetic unit 2, the exciting current can be controlled stably even if the power supply voltage decreases or the solenoid resistance increases due to the temperature rise of the solenoid due to the heat generation of the solenoid. Becomes possible.

The arithmetic unit 2 may be provided with a smoothing capacitor 30 and resistors 61, 62, 63 in the feedback path 9 as shown in FIG. Further, as shown in FIG. 6, the output voltage of the oscillator 11 may be input to the command voltage terminal 1 input to the arithmetic unit 2.

[0013]

As described above, according to the present invention, the dither signal can be applied to the exciting current flowing through the solenoid in accordance with the on / off operation of the power switching element only by providing one oscillator, and the number of components is reduced, thereby reducing the electric circuit. The configuration can be simplified, and the electromagnetic control valve control device can be reduced in size. In addition, since an arithmetic unit that outputs the difference between the excitation current setting signal and the output signal of the current detector to be smoothed is provided, the resistance of the solenoid increases due to a decrease in the power supply voltage and an increase in the temperature of the solenoid due to the heat generated by the solenoid. Even after that, since the exciting current can be controlled stably, accurate control of the electromagnetic control valve becomes possible.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram in which an exciting current waveform in the embodiment is enlarged and corresponding to an output pulse waveform of a comparator.

FIG. 3 is an explanatory diagram showing an exciting current waveform when a time constant of a solenoid changes.

FIG. 4 is an explanatory diagram showing an exciting current waveform of the first embodiment.

FIG. 5 is an electric circuit diagram of a second embodiment showing another example of the arithmetic unit.

FIG. 6 is a block diagram of an electric circuit showing a third embodiment.

[Explanation of symbols]

 1 command voltage terminal 2 arithmetic unit 6 comparator 11 oscillator 12 power transistor (power switching element) 13 solenoid 14 detection resistor (current detector) 15 flywheel diode

Claims (1)

(57) [Claims] 1. A power switching element for controlling on / off of a current from a power supply to a solenoid, a current detector connected in series to the solenoid to detect an exciting current flowing through the solenoid, and a parallel connection to the solenoid and the current detector. A flywheel diode for supplying an exciting current to the solenoid when the power switching element is turned off, and a computing unit for outputting a difference between a setting signal of the exciting current and an output signal of the current detector to be smoothed, A comparator is provided to guide these two signals so as to obtain an output signal of the current detector corresponding to the output signal of the above, to output a pulse signal according to the magnitude relationship between the two signals, and to turn on and off the power switching element, and An oscillator that outputs a periodic vibration signal has a vibration signal that becomes a dither signal in the output signal of the arithmetic unit to the comparator. An electromagnetic control valve control device connected to an output path of a computing unit or an input path of a setting signal.