JPH11108233A - Solenoid valve drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prohibit operation in the condition of not exchanging a troubled drive element to be continued and prevent the condition of a solenoid valve being unable to close from generating by fusing a fuse element so as to forcedly close the solenoid valve, when a short trouble is generated in a drive element controlling to open/close the solenoid valve. SOLUTION: A mechanical type relay 31 of drive element is connected to a current carrying circuit to a solenoid valve 21, and by operating the relay 31 the solenoid valve 21 is controlled to be opened/closed. Namely when the relay 31 is made ON, current is carried to the splenoid coil of the solenoid valve 21 to open the solenoid valve 21. Preparing for a short trouble of such relay 31, a fuse element 4 is connected to the solenoid valve in series, and the part between the fuse element 4 and the solenoid valve 21 is earthed through a relay 41 and resistance 42 constituting a forcedly valve closing circuit. At a short trouble in which the relay 31 is left in the ON condition, the fuse element 4 is fused to cut off the relay 31, and the relay 41 is made ON to forcedly close the solenoid valve 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve driving circuit in which a solenoid valve provided in a gas supply path is connected in series with a drive element for controlling the opening and closing of the solenoid valve.

[0002]

2. Description of the Related Art An electromagnetic valve is provided in a gas supply pipe of a gas appliance such as a gas heater or a water heater, and the electromagnetic valve is opened when an operation switch of the gas appliance is turned on. If the solenoid valve is not energized, it will be closed by the biasing force of the internal spring. If energized, the internal solenoid coil will be excited and the valve will be pulled up to open. Driving elements such as a mechanical relay and a semiconductor relay are connected in series to the solenoid valve. The drive element is turned off in the non-energized state, and the solenoid valve is not energized and is in the closed state. When the drive element is energized, the drive element is turned on, so that the solenoid valve is energized and the solenoid valve is opened.

When the drive element is short-circuited, the solenoid valve is kept energized and cannot be closed while the valve is open. For this reason, a plurality of drive elements are connected in series to the solenoid valve, so that even if one drive element is short-circuited, the remaining drive elements open and close the solenoid valve.

[0004]

By providing a plurality of drive elements, redundancy is increased, and when one drive element is short-circuited, the probability of another short-circuited drive element at the same time is extremely reduced. However, even if the redundancy is increased, not all the driving elements are short-circuited.
Even if one drive element is short-circuited and the operation can be continued by another drive element, if one drive element is short-circuited and the operation is continued by another drive element without repair, the other When a short-circuit fault occurs in the drive element, the solenoid valve remains open.

In view of the above problems, the present invention provides a solenoid valve drive circuit which forcibly closes a solenoid valve when a short circuit occurs in a drive element and prohibits subsequent operation. That is the task.

[0006]

According to the present invention, there is provided an electromagnetic valve driving circuit in which a driving element for controlling the opening and closing of an electromagnetic valve is connected in series to an electromagnetic valve provided in a gas supply path. And a forcible valve closing circuit for connecting the fuse element in series to the solenoid valve and forcibly closing the solenoid valve by blowing the fuse element due to a short-circuit failure of the drive element.

[0007] When a short-circuit failure occurs in a driving element, switching to open / close control by another driving element has conventionally been performed. In the present invention, when the occurrence of a short-circuit failure is detected, the fuse element is blown by a forced valve closing circuit so that the solenoid valve remains closed unless the fuse element is replaced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a gas hot air fan heater which blows hot air generated by a gas burner 11 into a room by a blowing fan 12. In the gas supply path 2 for supplying gas to the burner 11, solenoid valves 21 and 22 acting as safety valves and point fire extinguishing valves are arranged in order from the upstream side.
And a proportional control valve 23 having a governor function are connected in series. When an operation button (not shown) is pressed, the electronic control unit 3
Flows current through both solenoid valves 21 and 22 to open them,
The opening of the proportional control valve 23 is adjusted according to the temperature difference between the set temperature and the room temperature, and the gas burner 11 is ignited.

The circuits for driving the solenoid valves 21 and 22 have the same circuit configuration, and a drive circuit for the solenoid valve 21 will be described as an example. As shown in FIG. 2, a mechanical relay 31 which is a driving element is connected to the electromagnetic valve 21, and the electromagnetic valve 21 is opened and closed by operating the relay 31. That is, when the relay 31 is turned off, no current flows through the solenoid coil of the solenoid valve 21, and the solenoid valve 21 closes. Relay 31
Is turned on, a current flows through the solenoid coil of the solenoid valve 21 and the solenoid valve 21 is opened. Conventionally, relay 31
A similar relay is added to the solenoid valve 21 in case of a short circuit failure.
Was connected in series. In the present invention, without adding a relay,
Instead, the fuse elements 4 were connected in series. Then, the space between the fuse element 4 and the solenoid valve 21 was connected to ground via a relay 41 and a resistor 42. The relay 41 and the resistor 42 form a forced valve closing circuit. When a short-circuit failure that causes the relay 31 that is the drive element to remain in the on state occurs, the electronic control unit 3 turns on the relay 41. Relay 3
1 is short-circuited, current flows through the fuse element 4 to the solenoid coil of the solenoid valve 21, but when the relay 41 is turned on, the current flowing through the fuse element 4 further increases, and Fuse element 4 is blown by exceeding the allowable current. Once the fuse element 4 is blown out in this way, the solenoid valve 21 does not open unless the fuse element 4 is replaced. When the electronic control unit 3 blows the fuse element 4 in this way, the electronic control unit 3 notifies the fact by a lamp or the like.

In order to open the solenoid valve 21 again, the relay 31 and the fuse element 4 need to be replaced. Therefore, it is desirable that the relay 31 and the fuse element 4 are detachably configured by a socket or the like instead of directly connected to the electronic control unit. By the way, in the above embodiment, only one relay 31 as a driving element is provided, but a plurality of relays 31 may be provided. In addition, relay 31
41 uses a mechanical relay, but may use a semiconductor relay.

[0011]

As is apparent from the above description, according to the present invention, when a short-circuit fault occurs in the drive element for controlling the opening and closing of the solenoid valve, the fuse element is blown to forcibly close the solenoid valve. With this configuration, it is possible to prohibit the continuation of the operation without replacing the short-circuited drive element and prevent a situation in which the solenoid valve cannot be closed while being opened.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a gas appliance to which the present invention is applied.

FIG. 2 is a circuit diagram showing a main part of one embodiment of the present invention.

[Explanation of symbols]

 3 Electronic control unit 4 Fuse element 21 Solenoid valve 22 Solenoid valve 31 Relay (drive element) 41 Relay (part of forced valve closing circuit)

Claims (1)

[Claims] In a solenoid valve driving circuit in which a driving element for controlling opening and closing of the solenoid valve is connected in series to a solenoid valve provided in a gas supply path, a fuse element is connected in series to the solenoid valve. An electromagnetic valve drive circuit, comprising: a forced valve closing circuit for blowing the fuse element due to a short-circuit failure of the drive element and forcibly closing the electromagnetic valve.