JP2000065234A - Solenoid valve driving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To openly and closely control a solenoid valve with such a pattern that voltage is applied to a power supply terminal without making much current to the power supply terminal by controlling a solenoid current-carrying circuit on the basis of an output of a voltage detecting circuit by a control circuit. SOLUTION: When voltage is applied to a power supply terminal 1, a condenser 4 is charged with few current by a resistance 3, an opening current- carrying current in a solenoid 10 is supplied to the condenser 4. When voltage of the power supply terminal 1 is not applied, a closing current-carrying current is supplied from the condenser 4. Input current of the power supply terminal 1 flows for a comparatively long period, and instant much current is not necessitated. Since a timing such as opening current-carrying and a closing current- carrying times is controlled by a micro computer 6, closing and opening of a solenoid valve is controlled by application/non-application of voltage to power supply source 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for an electromagnetic valve for electrically controlling a fluid using a latching solenoid, particularly for controlling water discharge / water stoppage. The present invention relates to a driving method which does not require a circuit and can be operated with a small output power supply.

[0002]

2. Description of the Related Art A latching solenoid used in a solenoid valve consumes electric power instantaneously when controlling a fluid, for example, when switching between water discharge / stop water, but maintains the state of water discharge / stop water. Has the advantage of not requiring power. Further, assuming an actual use state, the drive time when switching between water discharge / water stoppage is several to several tens of msec, while the time for maintaining the water discharge / water stoppage state is, for example, automatic water for hand washing. Plugs and the like can last for seconds, minutes to hours, or even longer depending on the application. For this reason, when the drive power required for water discharge / water stoppage is averaged over the usage time of the solenoid valve,
Furthermore, the consumption becomes extremely low. Because of this extremely low power consumption, solenoid valves using latching solenoids are often used in equipment powered by batteries.

[0003] Further, even in the case of equipment using an AC commercial power supply, the power supply circuit requires only a small capacity, so that it is suitable for a case where the power supply circuit needs to be miniaturized. It is also a solenoid valve with suitable performance for problems.

[0004]

However, although the latching solenoid consumes very low power on average, it has a problem that a large current is required instantaneously. For example, in the case of the above-mentioned automatic faucet, the consumption required for driving the latching solenoid is only about several tens of μA on average over the entire use time, but the driving current required instantaneously during operation is several hundred mA. And increase. For this reason, when a battery is used as a power source, there is a problem in that the load on the battery is large, the types of batteries that can be used are limited, and the battery cannot be used when the battery capacity is not completely used up.

Further, even when a commercial power supply is used, the power supply circuit becomes large in order to be able to supply an instantaneous large current even though the power supply circuit has a very small capacity on average. However, there is a problem that a special device for flowing a large current instantaneously is required. Furthermore, when using either a battery or a commercial power supply, there is a load that requires a large amount of current momentarily, which greatly restricts the circuit, making the circuit complicated and expensive, as well as using a latching solenoid. There is also a problem that it is necessary to fully understand the characteristics of the solenoid valve, and improper design leads to malfunction of the solenoid valve.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make use of the advantage of a low-consumption latching solenoid without requiring a large current even instantaneously. An object of the present invention is to provide a solenoid valve driving circuit which does not require special consideration for the method.

[0007]

According to a first aspect of the present invention, there is provided a solenoid valve driving circuit for a solenoid valve using a latching type solenoid, comprising two input terminals, a power supply terminal and a ground terminal, and a solenoid. A power supply means for supplying current to the solenoid power supply circuit charged from a power supply terminal, a current limiting circuit for limiting a charging current from the power supply terminal to the power storage means, and a power supply. A voltage detection circuit for detecting the voltage of the terminal and a control circuit for controlling the operation of the solenoid energizing circuit are provided, and the control circuit controls the solenoid energizing circuit based on the output of the voltage detecting circuit. As a result, a large current does not flow through the power supply terminal, and the opening / closing of the solenoid valve can be controlled by the voltage application pattern to the power supply terminal.

According to a second aspect of the present invention, in the solenoid valve driving circuit of the first aspect, the voltage detection circuit is a circuit that determines a state where a voltage is applied to the power supply circuit and a state where the voltage is not applied to the power supply circuit. Thus, opening / closing of the solenoid valve can be controlled by the simplest operation of turning on / off the power supply to the power supply terminal.

According to a third aspect of the present invention, in the solenoid valve driving circuit of the first or second aspect, the current limiting circuit is a resistor. This makes it possible to easily limit the power supply current.

According to a fourth aspect of the present invention, in the solenoid valve driving circuit according to the third aspect, a prohibition time is provided from application of a voltage to a power supply terminal to activation of the solenoid energizing circuit. As a result, there is no danger that the solenoid will be energized while the power storage means is not sufficiently charged, thereby causing malfunction of the solenoid valve.

According to a fifth aspect of the present invention, in the solenoid valve driving circuit according to the first or second aspect, the current limiting circuit is a switching circuit. As a result, it becomes possible to arbitrarily charge the power storage means as needed.

According to a sixth aspect of the present invention, in the solenoid valve driving circuit of the fifth aspect, the switching circuit is operated after the voltage is applied to the power supply terminal and after the solenoid energizing circuit is operated. Thus, the power storage means is not uncharged when the solenoid is energized, and unnecessary switching operation is not performed.

According to a seventh aspect of the present invention, in the solenoid valve driving circuit of the first and second aspects, the current limiting circuit is a constant current circuit, so that the upper limit of the input current to the power supply terminal can be clearly set, and the charging of the power storage means can be performed. Finish in a short time.

According to an eighth aspect of the present invention, in the solenoid valve driving circuit according to the first to seventh aspects, a power supply backup means for the control circuit is provided. This is suitable for the operation of the control circuit, and when the power supply terminal is used as a control signal for energizing the opening / closing of the solenoid valve, the time for turning off the power supply as a control signal can be lengthened, and the control signal can be set. Degree of freedom can be increased.

According to a ninth aspect of the present invention, in the electromagnetic valve driving circuit of the eighth aspect, the backup means is supplied with power from the power storage means. This makes it possible to reduce the capacity of components such as a capacitor for backup means.

According to a tenth aspect, in the solenoid valve driving circuit according to the eighth or ninth aspect, the power supply terminal and the backup means are connected via a diode. Thus, when the power is turned off, the power terminal which is originally an input terminal becomes an output,
The inconvenience of unnecessarily discharging the charge of the backup means and the power storage means is eliminated.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to make the present invention easier to understand, a detailed description will be given below with reference to the drawings.

[0018]

(Embodiment 1) FIG. 1 shows a circuit diagram of Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a power supply terminal, and 2 denotes a ground terminal, which are a positive electrode and a negative electrode of a power supply, respectively. Power is supplied from the power supply terminal 1 to the capacitor 4, the solenoid energizing circuit 5, and the microcomputer 6 via the resistor 3. The solenoid energizing circuit 5 is an H-type bridge circuit composed of transistors 51 to 54.
The O2 output energizes the latching solenoid 10 of the solenoid valve (not shown) in the forward and reverse directions, and opens and closes the solenoid valve.
Reference numeral 7 denotes a voltage detection circuit for detecting whether the voltage of the power supply terminal 1 is Hi or Lo level.
Such a logic element, a comparator, a reset IC for detecting that the voltage has become equal to or lower than a predetermined value, or the like can be used.

FIG. 2 is a flowchart showing the main routine of the microcomputer 6. When a voltage is applied to the power supply terminal 1 in FIG. 1, the operation starts from the reset in S001 (step 001) in FIG. Wait one second in S002, S
At 003, open energization is performed.

FIG. 3 is a subroutine showing the details of the opening energizing operation in S003. In FIG. 3, P01 is selected in S301.
Is set to Hi and the transistors 51 and 52 are set to O
N, the solenoid 10 is energized in the valve opening direction. S302
Wait for 20 msec to elapse, set P01 to Lo in S303, stop energization, and return to the main routine from S304. Next, in S004, the voltage state of the power supply terminal 1 is changed to
A check is made based on the output of the voltage detection circuit 7 input to PI1 of the microcomputer 6. If PI1 is Hi, that is, if a voltage is applied to the power supply terminal 1, the loop goes around in S004. Here, when the voltage of the power supply terminal 1 decreases, that is, when no voltage is applied to the power supply terminal 1, S005
To start the timer, and in S006, the power supply terminal 1
Is checked, and if no voltage is applied, 00
The time is checked at 7 and when the voltage is applied again, S
Return to 004. When the state in which no voltage is applied continues for 5 ms, the process proceeds from S007 to S008, and close energization is performed.

FIG. 4 is a subroutine showing the details of the closing energizing operation in S008. Referring to FIG.
Is set to Hi and the transistors 53 and 54 are set to O
N, the solenoid 10 is energized in the valve closing direction. S402
Waits for 10 msec to elapse, sets P02 to Lo in S403, stops energization, and returns to the main routine from S404. Then, the voltage of the power supply terminal 1 is checked in S009. If the voltage has not been applied, the process goes through the loop in S009. If the voltage is applied, the process returns to the reset of S001.

The above operation example will be described with reference to the operation waveforms of FIG. In FIG. 5, VIN is the voltage of the power supply terminal 1, V
C is the voltage of the capacitor 4, VDD is the power supply voltage of the microcomputer 6, and VC and VDD are equal. Time T1 (hereinafter T
In 1), a voltage, for example, 5 V is applied to the power supply terminal 1. V
Although IN becomes 5 V from T1, the capacitor 4 is charged via the resistor 3, so that VC has a CR charging waveform as shown in FIG. 5, and becomes substantially equal to VIN at T2. During this time, the current flowing into the power supply terminal 1 is limited by the resistor 3, and thus is significantly smaller than the current flowing when the solenoid 10 is driven. When the power supply voltage VDD reaches the oscillatable voltage of the system clock, the microcomputer program
The operation starts from reset (S001). When one second has elapsed from the start of operation of the microcomputer at T3 (S002), PO
1 is turned on for 20 msec to perform open energization (S003). Most of the current to the solenoid 10 is supplied from the capacitor 4 by the action of the resistor 3, and only a small amount is supplied from the power supply terminal 1. VC temporarily drops in voltage due to the consumption of the open current from T3 to T4, but is charged again via the resistor 3 from T4.

If VIN is applied, the solenoid valve keeps this open state (S004). When VIN stops being applied at T5, measurement of this time starts (S005 to S005).
007) When 5 ms elapses, closes electricity at T6 (S008)
I do. At this time, most of the current to the solenoid 10 is supplied from the capacitor 4 as in the case of the energization from T3 to T4. Then, it waits for VIN to be applied (S009).
However, during this time, the microcomputer consumes a small amount of operating current, the electric charge of the capacitor 4 is gradually discharged, and the VC decreases. When the voltage of VIN recovers, it is reset in a software manner in S010. However, if the voltage continues to be applied without applying VIN, the VC drops and the microcomputer stops operating.
Is reset by hardware when is applied. Therefore,
It is always reset after T7.

As described above, when a voltage is applied to the power supply terminal 1, the capacitor 4 is charged with a small current by the resistor 3, an open current of the solenoid 10 is supplied from the capacitor 4, and the voltage of the power supply terminal 1 is applied. When it disappears, the closing current is supplied from the capacitor 4 as well. Therefore, although the input current of the power supply terminal 1 flows for a relatively long time, an instantaneous large current is not required. Further, since the microcomputer 6 controls the timing such as the time of opening energization and closing energization, the opening / closing of the solenoid valve can be controlled by applying / not applying a voltage to the power supply terminal 1. In addition, if the driving conditions specific to each solenoid are set in the microcomputer 6, the condition of the voltage applied to the power supply terminal 1 is the same even when different solenoids are used.

For these reasons, the power supply terminal 1 is connected to a simple Hi /
Driving is also possible with the Lo signal, and the conditions required for the circuit are greatly relaxed as compared with the case where the solenoid 10 is directly driven. In this embodiment, the power is turned on when the power is turned on (S003), and the power is turned off when the power is turned off (S008). However, this is usually the case where the solenoid valve is closed and the solenoid valve is opened when necessary. It is. On the other hand, the solenoid valve is normally open, and when the solenoid valve is to be closed when necessary, the energization of opening and closing in S003 and S008 in FIG. 2 may be reversed.

(Embodiment 2) FIG. 6 is a circuit diagram of Embodiment 2. FIG. 2 is a flowchart of the second embodiment, and the basic operation is the same as that of the first embodiment. In FIG. 6, a voltage is applied to the microcomputer 6 from the power supply terminal 1 via the diode 11. The power supply voltage VDD of the microcomputer 6 is a capacitor 12
Backed up by Furthermore, the resistance 3
Via the capacitor 4 is charged.

FIG. 7 shows an example of the operation waveform. The power supply VDD of the microcomputer 6 is more stable than in the first embodiment. This is preferable as the operating condition of the microcomputer 6. When the voltage is no longer applied to the power supply terminal 1, in the circuit of FIG.
Is applied in reverse. At this time, the electric charge of the capacitor 4 is unnecessarily discharged. In the circuit of FIG. 6, such a problem is not caused by the diode 11.

(Embodiment 3) FIG. 8 is a circuit diagram of Embodiment 3. FIG. 8 is a diagram in which the resistor 3 in FIG.
FF is performed. FIG. 9 is a flowchart showing a main routine of the microcomputer 6. The differences from FIG. 2 will be described.

After the reset of S001, the charge 1 is performed in S021.
Execute the subroutine. The operation details of Charge 1 are shown in FIG.
It is. In FIG. 10, a variable X is set to 10 in S501. In step S503, PO3 is set to Lo, and the transistor 1
Turn 3 ON. In step S504, an Xmsec timer is operated. Here, since X is 10, it is 10 msec. After 10 msec, PO3 is set to Hi in S505.
The transistor 13 is turned off. Therefore, 10m
During the second, the capacitor 4 is charged. Next, in S506, the timer of (80-X) msec is operated. X is 1
Since it was 0, wait 70 msec. 1 in X in S507
In step S508, it is determined whether X is greater than 80.
If 0 or less, the process returns to S503. When X becomes larger than 80, the process proceeds from S508 to S509 and returns to the main routine.

By the above operation, charging for 10 msec, 7
0 msec charging pause, 20 msec charging, 60 msec
When the charging is suspended (the same applies hereinafter), the charging time is gradually increased and the charging suspended time is shortened. Finally, the charging is performed for 80 msec, and the subroutine of the charging 1 is completed. This operation is shown in FIG.
The operation waveform is shown in FIG.

In FIG. 11, from time T1, PO3 gradually charges the capacitor 4 while gradually increasing the ON time of the transistor 13. The charging current flows more easily as the voltage of the capacitor 4 is lower, but since the charging time is initially short, the capacitor 4 is charged by an operation such as constant current charging as shown in FIG. Returning to FIG. 9, after S021,
In S003, open energization is performed. This is the same as in the first embodiment. Next, charging 2 is performed in S022. The details of this operation are shown in FIG. 10, where X is set to 50 from S502, and the operation after S503 is the same operation as charging 1. this is,
Since the operation is similar to the operation from time T9 in FIG. 11 and the voltage of the capacitor 4 is not as low as that at time T1, even if the ON time of the transistor 13 is lengthened from the beginning, a large current does not flow and charging is completed in a short time. I do. After S004 in FIG. 9,
It is the same as FIG.

In the first and second embodiments, the charging current of the capacitor 4 is limited by the resistor 3, but a large current flows at the beginning of charging. If this is to be suppressed to a small value, the value of the resistor 3 becomes large, the time constant with the capacitor 4 becomes large, and the time required for charging becomes too long.
If a switching element such as the transistor 13 is used, constant-current charging can be performed with simple control, and the charging time can be shortened while suppressing the maximum charging current. FIG.
Although the charging subroutine of 0 is a simple example, a method of changing the ON / OFF time of the transistor 13 exponentially or changing the ON / OFF time according to the charging voltage of the capacitor 4 is also possible.

Fourth Embodiment FIG. 12 is a circuit diagram of a fourth embodiment. The flowchart is FIG. 2, and the basic operation is the same as that of the second embodiment. 12, a diode 14 is added to FIG. This is for supplying power of the microcomputer 6 from the capacitor 4. In the circuit of FIG. 6, since the resistor 3 is inserted between the power supply VDD of the microcomputer and the capacitor 4, the charging current to the capacitor 4 is limited. Similarly, when the voltage application to the power supply terminal 1 is turned off, the power supply from the capacitor 4 to the microcomputer 6 is also limited. For this reason, the capacitor 12 shown in FIG. 6 needs to have a relatively large capacity in order to guarantee the operation of the microcomputer.

However, in FIG. 12, when the voltage application to the power supply terminal 1 is turned off, the power supply current is supplied from the capacitor 4 to the microcomputer 6 by the diode 14. Therefore, the purpose of the capacitor 12 is to absorb noise, and a capacitor having a very small capacity is sufficient. However, since the capacity of the capacitor 4 is large, the power supply backup capability of the microcomputer 6 is significantly improved.

(Fifth Embodiment) FIG. 13 is a circuit diagram of a fifth embodiment. The flowchart is FIG. 9, and the basic operation is the same as that of the third embodiment. 13, a diode 14 and a resistor 15 are added to FIG. The diode 14
It has the same purpose as the diode 14 in FIG. FIG.
3 does not supply power from the capacitor 4 to the microcomputer 6, the diode 14
It is more effective than the case of 2. The resistor 15 is for charging the capacitor 4 even when the transistor 13 is off. The resistance value of the resistor 15 may be relatively large. When the charging current is large at the initial stage of charging the capacitor 4, the base current for turning on the transistor 13 does not matter, but the use of the transistor immediately before the completion of charging is wasteful. If a resistor 15 having a large resistance value is connected in parallel with the transistor 13,
The driving of the transistor 13 is terminated at an appropriate stage, and the final charging can be performed via the resistor 15. Thereby, complete charging can be performed efficiently.

(Embodiment 6) FIG. 14 is a flowchart showing a main routine of Embodiment 6. The circuit is the same as that of the fourth embodiment shown in FIG. In FIG. 14, the process starts from reset in S101, and checks the voltage of the power supply terminal 1 in S102. If the voltage is applied, the process waits in S102. When the voltage application to the power supply terminal 1 is turned off in S102, the process proceeds to S103 and the timer is started. S10
It waits until the voltage of the power supply terminal 1 returns in the loop from 4 to S105. If one second elapses without voltage recovery, S1
The process proceeds to step S12, and waits forever until the voltage is restored. When the voltage is restored, the process returns from step S113 to step S101. In this case, similarly to S009 of FIG. 2, the reset is always performed in terms of software or hardware. If the voltage is restored without elapse of one second in S104, the process proceeds to S106, the timer is stopped, and in S107, S108, and S109, the time during which the voltage application to the power supply terminal 1 is OFF is determined. Power OF
If the F time is less than 5 msec or 25 msec or more, the process returns to S102. Power off time is 15
If it is not less than msec and less than 25 msec, open electricity is supplied in S110 and the process returns to S102, and 5 msec or more and 15 msec.
If the difference is less than the predetermined value, the power is closed in S111 and the process returns to S102.

As described above, when the power supply voltage is applied to the power supply terminal 1 and the power supply voltage is turned off for a predetermined period of time to return to the normal state, the open energization or the close energization is performed. Otherwise, no power is supplied, and if the power supply voltage has been OFF for an abnormally long time, the power supply is reset. FIG. 15 shows an example of the above operation waveform.

According to the sixth embodiment, the solenoid valve can be opened and closed at an arbitrary timing by a simple control of turning off the voltage of the power supply terminal for a predetermined time. The circuit configuration is the same as that of the fourth embodiment, and no large current flows to the power supply terminal 1. Therefore, as in the other embodiments, the solenoid valve can be controlled at an arbitrary timing with a voltage and a current of about a logic signal.
In the present embodiment, the power supply terminal is opened / closed at the time of turning off the voltage.
Although the close is distinguished, it may be distinguished by the number of times of turning off within an arbitrary time. Further, each time the power is turned off for a predetermined time, the open energization and the close energization can be alternately performed.

(Embodiment 7) In Embodiment 7, the operation of Embodiment 6 is applied to the circuit diagram of FIG. FIG. 16 is a flowchart showing the main routine of the seventh embodiment, and FIG. 17 shows an example of operation waveforms. In FIG. 16, compared to FIG.
21. Charge 1 of S21 and Charge 2 of S122 are added.
This is the same purpose and operation as the charge 1 of S021 and the charge 2 of S022 in FIG. As shown in FIG.
By the switching of 3, the charging current to the capacitor 4 is ideally controlled, and the solenoid valve can be controlled at an arbitrary timing.

(Embodiment 8) Embodiment 8 is different from Embodiment 6 in that the solenoid valve is not kept open. FIG. 18 is a flowchart showing the main routine of the eighth embodiment, and FIG. 19 shows an example of operation waveforms. FIG. 12 is a circuit diagram.

The difference between FIG. 18 and FIG. 14 will be described.
After the reset of S101, the charging of the capacitor 4 is waited in S131, and the close energization is performed in S132. Thus, when power is supplied to the circuit, the solenoid valve always starts from the closed state. The subsequent operation is the same as in FIG. However, power off
If the state continues for one second or more, the power is turned on in step S133, and the process enters a state of waiting for reset in step S112. For example, even in the case where the power supply to the control side by applying power to the circuit shown in FIG. 12 is turned off, the operation can be stopped by reliably performing the closed energization.

[0042]

According to the present invention, the following effects are exhibited by the above configuration.

According to the first aspect, a large current does not flow through the power supply terminal, and the opening / closing of the solenoid valve can be controlled by a voltage application pattern to the power supply terminal.

The power supply to the power supply terminal is turned ON / O.
The opening / closing of the solenoid valve can be controlled by the simplest operation of performing FF.

According to the third aspect, the power supply current can be easily limited.

According to a fourth aspect of the present invention, there is no danger that the solenoid is energized while the power storage means is not sufficiently charged, thereby causing malfunction of the solenoid valve.

According to a fifth aspect of the present invention, the power storage means can be arbitrarily charged as needed.

According to the present invention, the power storage means is not uncharged when the solenoid is energized, and no unnecessary switching operation is performed.

According to the present invention, the upper limit of the input current to the power supply terminal can be clearly set, and the charging of the power storage means is completed in a short time.

According to another aspect of the present invention, it is preferable in terms of the operation of the control circuit that, when the power supply terminal is used as a control signal for energizing opening / closing of the solenoid valve, the time for turning off the power supply as the control signal is lengthened. And the degree of freedom in setting control signals is increased.

According to the ninth aspect, the capacity of components such as a capacitor for backup means can be reduced.

According to the tenth aspect, when the power supply is turned off, the power supply terminal which is originally an input terminal becomes an output, and there is no inconvenience that the charge of the backup means and the storage means is uselessly discharged.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment.

FIG. 2 is a flowchart of a main routine in first, second, and fourth embodiments.

FIG. 3 is a flowchart of an opening energization subroutine in the first to eighth embodiments.

FIG. 4 is a flowchart of an opening energization subroutine in the first to eighth embodiments.

FIG. 5 is a voltage waveform showing an operation example of the first embodiment.

FIG. 6 is a circuit diagram of a second embodiment.

FIG. 7 is a voltage waveform showing an operation example of the second embodiment.

FIG. 8 is a circuit diagram of a third embodiment.

FIG. 9 is a flowchart of a main routine in the third and fifth embodiments.

FIG. 10 is a flowchart of a charging subroutine in the third, fifth, and seventh embodiments.

FIG. 11 is a voltage waveform showing an operation example of the third embodiment.

FIG. 12 is a circuit diagram of the fourth, sixth, and eighth embodiments.

FIG. 13 is a circuit diagram of the fifth and seventh embodiments.

FIG. 14 is a flowchart of a main routine in a sixth embodiment.

FIG. 15 is a voltage waveform showing an operation example of the sixth embodiment.

FIG. 16 is a flowchart of a main routine in a seventh embodiment.

FIG. 17 is a voltage waveform showing an operation example of the seventh embodiment.

FIG. 18 is a flowchart of a main routine in an eighth embodiment.

FIG. 19 is a voltage waveform showing an operation example of the eighth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power terminal 2 ... Ground terminal 3 ... Resistance 4 ... Capacitor 5 ... Solenoid valve energizing circuit 6 ... Microcomputer 7 ... Voltage detection circuit 10 ... Solenoid

Claims (10)

[Claims] 1. A solenoid valve driving circuit for a solenoid valve using a latching type solenoid, comprising: a power supply terminal and a ground terminal; two input terminals; a solenoid energizing circuit for energizing the solenoid in an opening direction or a closing direction; A power storage means charged from a terminal to supply a current to the solenoid energizing circuit, a current limiting circuit for limiting a charging current from the power supply terminal to the power storage means, a voltage detection circuit for detecting a voltage of a power supply terminal, A control circuit for controlling the operation of the solenoid energizing circuit, wherein the control circuit controls the solenoid energizing circuit based on an output of the voltage detection circuit. 2. The solenoid valve driving circuit according to claim 1, wherein the voltage detection circuit is a circuit that determines a state where a voltage is applied to the power supply circuit and a state where a voltage is not applied to the power supply circuit. Drive circuit. 3. The solenoid valve driving circuit according to claim 1, wherein the current limiting circuit is a resistor. 4. The solenoid valve drive circuit according to claim 3, wherein a prohibition time is provided between the time when the voltage is applied to the power supply terminal and the time when the solenoid energization circuit is activated. 5. The solenoid valve driving circuit according to claim 1, wherein said current limiting circuit is a switching circuit. 6. The solenoid valve driving circuit according to claim 5, wherein the switching circuit is operated after applying a voltage to the power supply terminal and after operating the solenoid energizing circuit. 7. The solenoid valve driving circuit according to claim 1, wherein the current limiting circuit is a constant current circuit. 8. The solenoid valve driving circuit according to claim 1, further comprising a backup unit for a power supply of said control circuit. 9. The solenoid valve driving circuit according to claim 8, wherein said backup means is supplied with power from said power storage means. 10. The solenoid valve driving circuit according to claim 8, wherein said power supply terminal and said backup means are connected via a diode.