JPS6338611B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid valve drive device for combustion equipment such as an instantaneous water heater. After ignition, the solenoid valve is held in place with a small amount of electric power.

In combustion equipment for instantaneous water heaters, for example, solenoid valves in gas supply systems have conventionally been operated by continuously applying a large amount of electric power required only during adsorption. However, even though this method does not require a large amount of power after adsorption, a large amount of power is always applied to the solenoid valve even after adsorption, which increases the temperature of the coil winding and causes performance deterioration. It is also a factor that affects lifespan. Furthermore, it also had the disadvantage of wasting power and wasting energy due to unnecessary heat generation.

The present invention provides a novel electromagnetic valve drive device that solves these conventional problems.

The invention will now be described in detail with reference to the illustrated embodiments.

In Fig. 1, 1 is a DC power source with starting force E;
B is a flame sensor that detects the presence or absence of combustion flame, which includes an AC power source 2, a capacitor 3, a resistor 4, and a flame rod 5.
It consists of: B is an oscillation circuit, with resistors 6, 7,
8, 9, 10, a capacitor 11, and an open collector type comparator 12. C is a variable pulse width circuit that changes the pulse width according to the output of the flame sensor; resistors 13, 14, 15, 16,
FET17, open collector type comparator 1
Consisting of 8. D is a drive circuit, which is composed of resistors 19, 20, 21, 22, and an open collector type comparator 23. Ho is DC−DC
In the converter, resistor 24, capacitor 25, 2
6, a transistor 27, an oscillation transformer 28, and a diode 29. 30 is a solenoid valve.

In the above configuration, when there is no combustion flame, there is no output from the flame sensor, so the gate voltage and source voltage of the FET 17 are equal, and the drain and source are in a shorted state. Therefore, the voltage at one input terminal of the comparator 18 of the variable pulse width circuit C is the voltage E of the DC power supply 1 divided by the resistors 13 and 14. Since this value is set lower than the voltage of capacitor 11 in oscillation circuit B, the output of comparator 18 is an open collector. At this time, the comparator 23 of the drive circuit 2 provides an output with an opposite phase to the output of the oscillation circuit 2, thereby switching the transistor 27 of the DC-DC converter circuit 2. As a result, in the initial stage of suction, the solenoid valve 30 is suctioned by the large power output of the DC-DC converter circuit E. This state is time t1-t2 in FIG.

Next, combustion starts at time t2, and when a flame is generated in the flame rod 5 of the flame sensor, a flame current flows in the direction of the arrow in FIG. 1 due to the rectifying action of the flame. Due to this flame current, the voltage at point c becomes negative potential by the voltage drop of resistor 4,
Turn off FET17.

Therefore, the voltage at one input terminal of the comparator 18 is raised and crosses the voltage at the capacitor 11, that is, the voltage at the +input terminal of the comparator 18. At this time, the negative input terminal voltage of the comparator 18 is the voltage E of the DC power supply 1, the voltage E of the resistor 13 and the resistor [14+1
5]. Therefore, the output of the comparator 18 is at a high level only when the +input terminal voltage is higher in potential than the -input terminal voltage, and is zero at other times. At this time, DC−DC
The drive waveform for switching the transistor 27 of the converter E is a combination of the output of the comparator 23 of the drive circuit D and the output of the comparator 18 of the variable pulse width circuit C. As a result of this synthesis, the width of the drive pulse becomes narrower, the time during which the transistor 27 of the DC-DC converter E is turned on becomes shorter, the output of the DC-DC converter E decreases, and the electromagnetic valve 30 has a small voltage that satisfies its holding voltage. Only electricity is supplied. This state is from time t2 to t3 in FIG.

In the above embodiment, the explanation was given by combining the output of the comparator 23 in the drive circuit D and the output of the comparator 18 in the variable pulse width circuit C in relation to the voltage applied to the solenoid valve 30. When the voltage of 30 is initially DC, the comparator 23 in the drive circuit 2 is unnecessary. In that case, the drive pulse becomes the output of the comparator 18 in FIG. 2, and the drive circuit of the DC-DC converter becomes the comparator 18.

In addition, the resistors 13, 14 of the variable pulse width circuit C,
By changing the value of 15, the pulse width setting can be arbitrarily changed and can be matched to the performance of the solenoid valve 30.

As described above, in the present invention, before combustion ignition, large electric power is applied to the solenoid valve to create an adsorption state, and after combustion ignition, the output of the flame sensor controls the drive pulse of the DC-DC converter to control the electromagnetic valve. Since the power applied to the valve is switched from the initial high power to low power, the heat generation of the solenoid valve coil is suppressed,
It can extend your lifespan. Furthermore, since there is no wasteful heat generation, there is no power loss, and energy savings can be expected.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is a voltage waveform diagram of each part. A is a flame sensor, B is an oscillation circuit, C is a variable pulse width circuit, D is a drive circuit, E is a DC-DC converter, 1 is a DC power supply, 5 is a flame rod, 1
2, 18, and 23 are open collector type comparators, and 30 is a solenoid valve.

Claims (1)

[Claims] 1. A solenoid valve that supplies fuel to form a combustion flame, a flame sensor that detects the presence or absence of the combustion flame,
A variable pulse width circuit that changes the pulse width based on the output of the sensor, a drive circuit that operates based on the output of the variable pulse width circuit, and a DC-DC converter that operates based on the drive circuit and uses the electromagnetic valve as a load. The variable pulse width circuit changes the pulse width depending on the presence or absence of an output from a flame sensor, and switches the electric power applied to the solenoid valve from a large electric power at the initial stage of adsorption to a small electric power after combustion is detected. Drive device. 2. The electromagnetic valve drive device for combustion equipment according to claim 1, which uses a flame rod as the flame sensor.