JPH0339660Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a solenoid valve used in hydraulic equipment, etc., and in particular, the present invention is concerned with a solenoid valve used in hydraulic equipment, etc., and in particular, the solenoid is energized by a small current on/off control signal from a signal line separated from the solenoid excitation power source. -Relates to a current signal controlled solenoid valve that controls deenergization.

[Conventional technology]

For example, Japanese Patent Laid-Open No. 59-58283 discloses that by controlling the opening and closing of solenoid valves based on optical signals, electrical noise and electromagnetic induction interference (EMI) can be removed, and compatibility with computer control systems can be improved. It is publicly known from the publication No.

However, in principle, it is possible to control a switching element using an optical signal sent through an optical fiber as a signal line, and use this to control the excitation of a solenoid plunger device of a solenoid valve, but in practice, In order to prevent vibrations during operation of the solenoid valve, dirt in the environment around the solenoid valve, etc., it is necessary to take considerable measures to connect the optical fiber and the electromagnetic valve electrical equipment.

[Problem that the invention attempts to solve]

The problem of this invention is to send the solenoid excitation on/off control signal separately from the solenoid excitation current using normal electrical wiring without using optical fiber as a signal line, and to send the solenoid on/off control signal to the signal line separately from the solenoid excitation current. Solenoids are less susceptible to the effects of electrical noise during operation, and are less likely to be affected by EMI due to the noise in the power supply line to peripheral equipment via the signal line. To provide a current signal controlled solenoid valve in which a switching element does not malfunction even if a leakage current other than an input signal occurs in a signal line when increasing the gain of a switching element for excitation on/off.

[Means for solving problems]

In order to solve the above-mentioned problems, the current signal controlled solenoid valve of the present invention has a series circuit of a solenoid coil and a switching element connected between a pair of power terminals, a signal input terminal, and the signal input terminal. a photocoupler device that generates an output signal for controlling conduction/cutoff of the switching element in response to an on/off input signal applied to the switching element; and a photocoupler device that limits the value of the current flowing to the input side of the photocoupler device in response to the input signal. and a voltage non-linear element that is inserted in series on the input side of the photocoupler device and inputs the current to the photocoupler device only when the terminal voltage exceeds a predetermined voltage value.

In a preferred embodiment of the present invention, the voltage non-linear element is a Zener diode connected in series with a current limiting element. Further, the current limiting element is preferably a constant current diode, but may be a resistor for simplicity.

[Effect]

In the solenoid valve of the present invention, a signal input terminal for on/off control of the solenoid is provided separately from the solenoid coil power supply terminal, and the value of the current flowing from the signal input terminal to the input side of the photocoupler device is limited by the current limit. The current is limited to a small value by the element,
Furthermore, this current does not flow unless the terminal voltage of the voltage nonlinear element exceeds a predetermined value, so noise generated when the solenoid turns on and off does not affect the signal line connected to the signal input terminal, and the power supply It is possible to prevent the above noise from being emitted from the line to the outside as much as possible, and furthermore, it is extremely unlikely to give noise or EMI to other equipment via the signal line, so it is practically possible to use an optical fiber signal line. You can get something that has the same performance as the original. In addition, the current flowing from the signal input terminal to the input side of the photocoupler device will not flow unless the terminal voltage of the voltage nonlinear element exceeds a predetermined value. The photocoupler device will not cause the switching device to malfunction unless the magnitude is such that it causes the voltage nonlinear device to conduct.

A preferred embodiment of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 1 shows a DC solenoid excitation control circuit for a solenoid valve according to an embodiment of the present invention, and includes a valve body of a solenoid valve, a valve body moving inside the solenoid valve body, and a machine such as a solenoid plunger device for driving the valve body. Some parts are omitted from illustration.

In FIG. 1, 10 is a terminal box attached to the valve body, and has a pair of power terminals 15, 16.
and a plug terminal 17,1 for connecting the solenoid coil 19 of the solenoid plunger device.
8, a signal power input terminal 3, and a signal input terminal 4. A DC solenoid excitation power supply 20 is connected to the power supply terminals 15 and 16 via a power line, a solenoid coil 19 is connected to the plug terminals 17 and 18, and the positive pole of the signal power supply 1 is connected to the terminal 3 through a signal line 36. Further, the negative electrode of the signal power source 1 is connected to the terminal 4 via the control switch 2 by a signal line 37. In this case, the switch 2 is shown as a contact, but in reality, a switching element such as a transistor or a switching output from a sequencer, a programmable controller, etc. is used.

In the terminal box 10, a series circuit consisting of a solenoid coil 19 and a Darlington type power switching transistor 12 as a switching element is connected between the power terminals 15 and 16 via the plug terminals 17 and 18, and a solenoid coil 19 and a Darlington type power switching transistor 12 as a switching element are connected. A photodiode 13 for displaying current-on and off-state operations and a surge absorbing element 14 are connected in parallel with the coil 19. A resistor 11, a constant voltage diode 9, and a smoothing capacitor 8 connected between the power supply terminals 15 and 16 serve as an internally stabilized power supply for converting the non-smooth DC output of the DC solenoid excitation power supply, which generates a pulsating output, into a stabilized DC output. It constitutes a circuit, and its output supplies power to the photocoupler device 6. The photocoupler device 6 is a normal type in which a phototransistor 6-2 on the output side generates a current output when a light emitting diode 6-1 on the input side emits light, and the base current of the power switching transistor 12 is changed by this phototransistor on the output side. It is now possible to control on/off.

On the input side of the photocoupler device 6, a forward constant current diode 5 as a current limiting element and a bidirectional Zener diode 21 are inserted in series between the signal power input terminal 3 and the anode side of the light emitting diode. , the cathode side of the light emitting diode 6-1 is connected to the signal input terminal 4. This constant current diode 5 operates within a certain range, e.g.
It is designed to allow a current of ~20mA to flow, and if the voltage level of the signal power source prepared by the user of the solenoid valve is known, the current limiting element can be set with an appropriate resistance value. A fixed resistor may be used instead. If not, specify the upper and lower limits of the signal power supply voltage, for example 5 to 100v, and then
By using a constant current diode selected so that it can obtain a constant current of 10 to 20 mA at a voltage value within that range as a current limiting element, the product can be made to have a wide range of compatibility with the signal power supply on the user side. Even if the voltage value of the signal power supply differs, a product can be obtained that does not require adjustment or replacement of the current limiting element.

Further, the bidirectional Zener diode 21 is used when the switch 2 is a switching output section of a programmable controller, for example.
The leakage current that occurs when the light emitting diode 6-
1, the corresponding phototransistor 6
Since the high gain Darlington power switching transistor 12 becomes conductive with a minute current output of -2, it is inserted to prevent this.
For example, assuming that the voltage of the signal power supply 1 is 24V, the pinch-off starting voltage of the constant current diode 5 is 5V, and the forward voltage drop of the light emitting diode 6-1 is 0.4V, the Zener diode 21 has a voltage of 24-(5+0.4). ) = 18.6 [V] Use one with a lower Zener voltage. The value of this Zener voltage determines the width of the dead zone against leakage current and noise, and the lower limit value is preferably about 3V. For example, in the above voltage example, if the Zener voltage of the Zener diode 21 is 15V, even if an element with leakage current is used in the switch 2, the voltage between terminals 3 and 4 will be 15+5+0.4= No current will flow through the light emitting diode 6-1 unless it exceeds 20.4 [V].

In the illustrated example, a bidirectional Zener diode 21 is used, but the present invention is not limited to this, and various voltage non-linear devices including a normal unidirectional Zener diode are used. It goes without saying that any element can be used.

In the configuration shown in FIG. 1, when the switch 2 is in the OFF state, the light emitting diode 6 on the input side of the photocoupler 6
Since no current flows through the transistor -1 and the point A is at a low level, the power switching transistor 12 remains off. In this case, even if a leakage current occurs in the switch 2, no current flows through the light emitting diode 6-1 unless the terminal voltage of the Zener diode 21 becomes large enough to exceed the Zener voltage. When the switch 2 is turned on, a sufficiently large voltage of the signal power supply 1 is applied between the terminals 3 and 4, and the terminal voltage of the Zener diode 21 exceeds the Zener voltage.
1 becomes conductive, a signal current limited to a constant value by the pinch-off operation of the constant current diode 5 flows through the light emitting diode 6-1 on the input side of the photocoupler 6, and as a result, the phototransistor 6-2 generates a current output and provides power. Switching transistor 12 becomes conductive and solenoid coil 19 is energized.

FIG. 2 shows another embodiment of the present invention, in which the signal power input terminal is not provided, and instead, the signal power is obtained from the power supply terminal 15, so that the power supply terminal 15 and the current limiting constant current diode are connected to the power supply terminal 15. 5, and the signal input terminal 4 is connected to the power supply terminal 16 via the switch 2 by signal lines 37 and 38. The other circuit parts are not much different from the example shown in FIG. 1, and the operation is also the same.

In FIG. 2, reference numeral 22 denotes a display light emitting diode that emits light in two colors, red and green. When current flows into the input of the photocoupler device 6, it emits red light, and when it is off, the surge absorbing element 14 is activated. It is designed to be displayed with a green light emitting display.

In FIG. 2, the anode of the constant current diode 15 is connected to the power supply terminal 15 by the internal connection circuit 39, but this may of course be connected to the connection point B between the resistor 11 and the resistor 7, or alternatively, The anode of the light emitting diode 6-1 may be connected to the connection point B through another resistor instead of the current diode 15.

[Effect of idea]

As described above, according to the present invention, the power terminal of the solenoid coil and the signal line can be separated, so that noise when the solenoid is turned on and off is less likely to be transmitted to the signal line, and the excitation power line and the signal line are separated, and the The signal line can be laid out in a way that prevents noise from coming out from the line, and it also reduces the risk of EMI being transmitted from the signal line to other peripheral devices.Furthermore, only a limited amount of current flows through the signal line. Therefore, there is less noise generation in this respect as well. Best of all, even if a leakage current occurs in the input, the action of the voltage non-linear element prevents the switching element from malfunctioning due to leakage current, making it possible to form a compact electric circuit using a normal photocoupler device and a high-gain switching element. Therefore, it is possible to achieve structural advantages in a solenoid valve built into an electric circuit component.

Normally, when manufacturing hydraulic equipment, the electrical equipment that operates the solenoid valves, including the power supply for the solenoid valve solenoid, is generally manufactured by the electrical manufacturer using the same or shared power supply for other electronic equipment. However, when using the solenoid valve of the present invention, the power source for excitation of the solenoid valve solenoid can be separated from the power source of other electronic and electrical devices, so the solenoid valve manufacturer or hydraulic equipment manufacturer can independently manufacture the power source. in this case,
A dedicated power supply for a solenoid valve solenoid does not require a constant voltage/constant current power supply, and it can be manufactured at a low cost because it does not require a constant voltage or constant current power supply, and there is no problem even if some leakage current occurs.

The solenoid valve of the present invention requires an input signal power source in addition to the excitation power source, but the output power source is 10 (mA) ~
Since it only requires a power supply for LEDs of about 20 (mA), it has the advantage of being able to be used in common with power supplies for other electronic devices, and it is difficult for noise to be transmitted to this signal system when the solenoid turns on and off.

Furthermore, the solenoid valve of the present invention can be operated by applying a small current switching signal of 10 to 20 (mA) to a signal line separated from the excitation power supply line, so it can be used as an output unit for a normal sequencer or programmable controller for light loads. This means that the valve can be directly controlled by a single type of output unit, regardless of whether it is a DC solenoid valve or an AC solenoid valve.In particular, internal signal power type models can be directly controlled by the output of a sequencer, etc., without using an output unit. In this case, the solenoid valve will not malfunction even if there is some leakage current in the output of the sequencer etc. when it is off.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a solenoid excitation control circuit for a DC solenoid valve according to one embodiment of the present invention, and FIG. 2 is a circuit diagram showing another embodiment. 3...External signal power input terminal, 4a, 4b...
Signal input terminal, 5... constant current diode (current limiting element), 6... photocoupler device, 12... power switching transistor (switching element), 15, 16... power supply terminal, 19... solenoid coil, 20... ... Excitation power supply, 21 ... Zener diode (voltage nonlinear element).

Claims (1)

[Claims for Utility Model Registration] 1. A series circuit of a solenoid coil and a switching element connected between a pair of power supply terminals, a signal input terminal, and the above-mentioned circuit according to an on/off input signal applied to the signal input terminal. a photocoupler device that generates an output signal for controlling conduction/cutoff of a switching element; a current limiting element that limits the value of a current flowing to the input side of the photocoupler device according to the input signal; and an input side of the photocoupler device. A current signal controlled solenoid valve comprising: a voltage non-linear element inserted in series with a voltage non-linear element that causes the current to be input to the photocoupler device only when the terminal voltage exceeds a predetermined voltage value. 2. The solenoid valve according to claim 1, which is equipped with a constant current diode as a current limiting element. 3. The solenoid valve according to claim 1 of the utility model registration, which is provided with a resistor as a current limiting element. 4. The electromagnetic valve according to claim 1, which is equipped with a Zener diode connected in series to a current limiting element as a voltage non-linear element.