JPH09217855A - Solenoid valve drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a consumption power to a limit through reduction of power consumption by a current limit element to a zero. SOLUTION: A solenoid valve 13 and a Zener diode D1 are interconnected in series between source terminals 12a and 12b and a semiconductor element T1 for drive is connected to in parallel to the Zener diode D1. During drive of the solenoid valve, the Zener diode D1 is brought into short-circuit through the semiconductor element T1 for drive to cause a flow of a high drive current necessary to drive. After drive of the solenoid valve 13, the semiconductor element T1 for drive is brought into an OFF-state after a lapse of a specified time, and the Zener diode D1 is rendered effective and this way limits a steady current to a low value. In this case, since power consumption by the Zener diode D1 is low enough for ignorance, a consumption power is extremely reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve drive circuit for driving a solenoid valve, and more specifically, it is an energy saving system that limits a steady current flowing through the solenoid valve during operation to reduce power consumption. The present invention relates to a solenoid valve drive circuit of a type.

[0002]

2. Description of the Related Art As a drive circuit of this type, a drive circuit disclosed in Japanese Utility Model Publication No. 5-47334 is known.
As shown in FIG. 4, the solenoid valve 2 and the current limiting resistor R are connected in series between the power supply terminals 1a and 1b, the driving transistor Ta is connected in parallel with the current limiting resistor R, and The solenoid valve is provided with a control transistor Tb for on / off controlling the drive transistor Ta and a delay circuit 3 for operating the control transistor Tb with a certain delay time after the solenoid valve 2 is driven. 2 is driven, the current limiting resistor R is short-circuited by the driving transistor Ta to cause a large driving current to flow in the circuit to drive the solenoid valve 2. After the solenoid valve 2 is driven, the delay circuit 3 sets the delay time. After a certain delay time, the control transistor Tb is operated to turn off the driving transistor Ta, and the current limiting resistor R is used to limit the steady current flowing through the solenoid valve 2. By limiting the steady-state current flowing through the solenoid valve 2 during operation to the minimum necessary amount, such a drive circuit can significantly reduce power consumption as compared with the case where the current is not limited. Since the resistor R is used as the current limiting element, power consumption due to heat generation or the like cannot be avoided in the portion of the resistor R, and in a recent control mechanism that collectively controls many solenoid valves, The power consumption and heat generation due to the current limiting resistor R cannot be ignored.

[0003]

SUMMARY OF THE INVENTION A main object of the present invention is to provide a solenoid valve drive circuit in which the power consumption due to the heat generation of the current limiting element is eliminated and the power consumption is minimized. Another object of the present invention is to provide a solenoid valve drive circuit having a simple structure, which can significantly reduce the power consumption without making a large modification to the conventional drive circuit.

[0004]

In order to solve the above-mentioned problems, a solenoid valve drive circuit according to the present invention includes a solenoid valve between power supply terminals and a current limiting element for limiting a steady current flowing through the solenoid valve during operation. Control for connecting in parallel with the current limiting element, connecting in parallel with the current limiting element a driving semiconductor element that short-circuits the current limiting element when driving the solenoid valve, and controlling ON / OFF of the driving semiconductor element. And a delay circuit for turning off the driving semiconductor element by operating the controlling semiconductor element after a certain delay time after driving the solenoid valve. It is characterized in that it is constituted by a Zener diode, and is connected in the opposite direction between the solenoid valve and the negative power source terminal.

In the drive circuit having the above structure, when the solenoid valve is driven, the driving semiconductor element is turned on and the Zener diode is short-circuited. Therefore, a large drive current based on the internal resistance of the solenoid valve flows to the solenoid valve. Switches. When a certain delay time elapses, the control semiconductor element is activated and the driving semiconductor element is turned off, so that the short circuit of the Zener diode is released and the solenoid valve is connected in series. Therefore, the steady current flowing through the solenoid valve is limited to a small value based on the characteristics of the Zener diode, and the limited steady current keeps the solenoid valve in an operating state. In this case, since the power consumption by the Zener diode is almost negligible, the power consumption in the steady state is substantially due to the internal resistance of the solenoid valve, and as a result, the resistor is used as the current limiting element. Compared with the conventional product, the power consumption when the same steady current is passed can be reduced to a significantly small value.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of a drive circuit according to the present invention.
Power source terminal 12a connected to switch 0 through switch 11,
Between the coil 12a and the coil 13a of the solenoid valve 13, the solenoid valve 1
3 is connected in series with the Zener diode D1 as a current limiting element for limiting the steady current flowing in the coil 13a during the operation of the Zener diode D1 in the opposite direction, and in parallel with the Zener diode D1. When the solenoid valve 13 is driven, the Zener diode D
1 is connected to a driving semiconductor element T1 which is short-circuited, and further, a controlling semiconductor element T2 for controlling on / off of the driving semiconductor element T1 and the above-mentioned controlling semiconductor element T2 after a certain delay time after the solenoid valve 13 is driven. It is constructed by connecting the delay element 14 which turns off the driving semiconductor element T1 by operating the semiconductor element T2.

Each of the driving semiconductor element T1 and the controlling semiconductor element T2 is composed of a grounded-emitter transistor, and the delay circuit 14 is composed of a resistor R14 and a capacitor C14. Is connected to: That is, the Zener diode D1 is connected between the collector C1 and the emitter E1 of the driving semiconductor element T1, and the base B1 of the driving semiconductor element T1 is connected to the collector C2 of the controlling semiconductor element T2. Power supply terminal 1 on the positive side via resistor R1
It is also connected to 2a. On the other hand, the control semiconductor element T2
Has its emitter E2 connected to the minus power source terminal 12b, and its base B2 is connected to the minus power source terminal 12b via a delay capacitor C14, and has a delay resistor R
A resistor R2 is connected to the power source terminal 12a on the positive side via 14 and in parallel with the delay capacitor C14.

In the drive circuit having the above structure, the switch 1
When 1 is closed, the driving semiconductor element T is connected through the resistor R1.
A base current flows through the semiconductor element T1 to turn on the semiconductor element T1, and the collector C1 and the emitter E1 are electrically connected to each other so that the Zener diode D1 is short-circuited. Therefore, a large driving current based on the internal resistance r of the coil 13a is generated. Flows and the solenoid valve 13 is switched. In this case, the control semiconductor element T2 is in the non-operating state because the base current does not flow until the charging of the delay capacitor C14 is completed due to the charging of the delay capacitor C14.

When the delay capacitor C14 is completely charged after a delay time determined by the size of the delay resistor R14 and the capacitance of the delay capacitor C14 in the delay circuit 14, a base current flows through the controlling semiconductor element T2. Since the control semiconductor element T2 is turned on and the collector C2 and the emitter E2 are brought into conduction, the base current of the driving semiconductor element T1 is cut off and the driving semiconductor element T1 is turned off. Therefore, Zener diode D1
Is connected in series to the coil 13a, the steady current flowing through the coil 13a is limited to a small value by the characteristics of the Zener diode D1, and the coil 13a is kept in the operating state by the limited steady current.

In this case, since the power consumption by the Zener diode D1 is small enough to be ignored, the power consumption in the steady state is substantially the coil 1 of the solenoid valve 13.
It can be considered only due to the internal resistance r of 3a,
Compared with the conventional one using a resistor as the current limiting element, the power consumption when the same steady current is passed can be significantly reduced.

This point will be specifically described using numerical values. For example, in the conventional drive circuit shown in FIG. 4, the resistance value of the internal resistance r of the solenoid valve 2 and the current limiting resistance R is 1: 2.
Assuming that the relationship (R = 2r) is set,
The power P1 consumed by the internal resistance r and the current limiting resistance R is P1 = Pr + PR = (E / 3), where Pr is the power consumption of the internal resistance r and PR is the power consumption of the current limiting resistance R. the ^{2 / r + (2E / 3} ) 2 / R = (E 2/9) · (1 / r + 4 / R) = 3E 2 / 9r.

On the other hand, in the drive circuit of FIG. 1 which uses the Zener diode D1 as the current limiting element, the operating resistance of the Zener diode D1 and the coil 13a.
The internal resistance r of the internal resistance r is
And the current limiting resistance R
A steady current having the same magnitude as that of the conventional example flows through the coil 13a and the Zener diode D1, but the power consumption in the Zener diode D1 is almost negligible due to its characteristics, so the total power consumption P2 is P2 ≠ Pr = E ² / 9r. Therefore, the ratio of both becomes P1 / P2 = 3, and the power consumption P2 when the Zener diode D1 is used.
Is only 1/3 of the power consumption P1 when the current limiting resistor R is used.

Further, the Zener diode D1 is not only effective in reducing the power consumption, but also
Driving semiconductor element T1 from the coil 13a or power supply side
Absorbs the surge voltage that acts on the driving semiconductor element T
It will also have the function of protecting 1. In this way, by using the Zener diode D1 as the current limiting element, the power consumption in the steady state can be greatly reduced and the energy can be saved without making a large modification to the conventional circuit using the resistor. It is possible to achieve the maximum limit, and moreover, it becomes possible to absorb the surge voltage acting on the driving semiconductor element T1 and reliably protect the driving semiconductor element T1, and enhance the durability and operation stability. be able to.

FIG. 2 shows a second embodiment of the drive circuit of the present invention. This drive circuit has another structure between the delay resistor R14 and the plus side power supply terminal 12a in the drive circuit of the first embodiment. A resistor R3 is connected and both resistors R3 and R14 are connected.
A constant voltage diode D2 is connected between the space and the negative power supply terminal 12b to stabilize the supply of the base current to the controlling semiconductor element T2. Since the other construction and operation are substantially the same as those of the first embodiment,
The same portions are denoted by the same reference numerals and description thereof will be omitted.

FIG. 3 shows a third embodiment of the drive circuit according to the present invention. This drive circuit has a constant current diode D3 connected in place of the resistor R3 in the drive circuit of the second embodiment. A resistor R4 is connected instead of the voltage diode D2, and the resistor R2 located in parallel with the delay capacitor C14 is omitted to stabilize the supply of the base current to the controlling semiconductor element T2. Since the other structure and operation are substantially the same as those of the second embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0016]

According to the solenoid valve drive circuit of the present invention, by using the Zener diode as the current limiting element, a very simple circuit can be realized without making a great change to the conventional circuit using the resistor. Only by making modifications, it is possible to drastically reduce the power consumption in the steady state and achieve energy saving to the maximum, and also to absorb the surge voltage that acts on the driving semiconductor element to ensure the driving semiconductor element. Can be protected, and durability and operational stability can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a drive circuit according to the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the drive circuit according to the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the drive circuit according to the present invention.

FIG. 4 is a configuration diagram of a conventional drive circuit.

[Explanation of symbols]

12a, 12b Power supply terminal 13 Solenoid valve 14 Delay circuit D1 Zener diode T1 Driving semiconductor element T2 Controlling semiconductor element

Claims (1)

[Claims] 1. A solenoid valve and a current limiting element for limiting a steady current flowing through the solenoid valve during operation are connected in series between power supply terminals, and the solenoid valve is driven in parallel with the current limiting element. A control semiconductor element, which is connected to a drive semiconductor element that sometimes short-circuits the current limiting element, and which controls ON / OFF of the drive semiconductor element, and the control semiconductor element after a certain delay time after driving the solenoid valve. A delay circuit for turning off the driving semiconductor element by operating the semiconductor element is connected, and the current limiting element is composed of a Zener diode, and a reverse circuit is provided between the solenoid valve and the negative side power supply terminal. Solenoid valve drive circuit characterized by being connected in the direction.