JPH04320715A - Controller of vaporization type burner - Google Patents

Abstract

PURPOSE:To lower the electro-magnetic noises in the solenoid that opens and closes the varporization nozzle of a vaporization type burner. CONSTITUTION:A solenoid 14 and a transistor 23 are connected in series to a rectifying circuit 21, and an oscillation circuit 27 is connected to the base of the transistor 23. With this arrangement the wave shape of the applied voltage at the time of holding the solenoid by suction is cut small by the output of the oscillation circuit 27 and the electromagnetic noises become low.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid control device for opening and closing a vaporized gas jet nozzle in a liquid fuel vaporizing combustor.

0002

2. Description of the Related Art FIG. 4 is a sectional view of a conventional vaporizing combustor. In the figure, 1 is an oil tank, 2 is an electromagnetic pump that supplies kerosene 3 from the oil tank 1 to the vaporizer 4 through an oil pipe 5, and 6 is a heater that heats the vaporizer 4. During combustion, the temperature sensor 7 detects the vaporization. The temperature of vessel 4 is kept constant. Reference numeral 8 denotes an outer tube communicating with the vaporizer 4, and a nozzle hole 11 at the tip thereof opens toward a burner 10 in which an igniter 9 is disposed. 12 is a needle with a needle-shaped tip for opening and closing the nozzle hole 11, 13 is a movable piece integrated with the needle 12, 14 is a solenoid that slides the movable piece 13, and 15 is a de-energized solenoid 14. A coil spring 16 pushes the movable piece 13 leftward in the figure to close the nozzle hole 11 when the solenoid 14 is energized, and a return pipe 17 through which kerosene communicates with the oil tank 1 when the nozzle hole 11 is opened by energizing the solenoid 14. This is a return valve to prevent the liquid from flowing to the side, and is integrated with the movable piece 13.

Next, the operation of this vaporization type combustor will be explained. First, the heater 6 is energized to heat the vaporizer 4. When the temperature of the vaporizer 4 detected by the temperature sensor 7 reaches a predetermined temperature and preheating is completed, the electromagnetic pump 2 is operated to supply kerosene from the oil tank 1 to the vaporizer 4 through the oil pipe 5. is heated and becomes a vaporized gas. At this time, when the solenoid 14 is energized, the needle 12
slides to the right in the figure to open the nozzle hole 11. Therefore, the vaporized gas is ejected from the nozzle hole 11, and at this time, primary air that acts as combustion air is sucked in from the surroundings, and the air-fuel mixture is ignited by the ignition device 9, which starts discharging as soon as the upper part of the burner 10 is preheated. , start combustion.

FIG. 5 shows the operation of the solenoid 14 in relation to the voltage applied thereto. That is, during the preheating period of the vaporizer from immediately after the start of operation to t1 seconds, no voltage is applied to the solenoid 14, and no voltage is applied to the nozzle hole 1.
1 is in a blocked state. Next, t1 when preheating is completed
At the beginning of the combustion period from time to time t2,
Since it is necessary to pull the needle 12 with a strong force against the force of the coil spring 15, a high DC voltage V obtained by rectifying the AC power source is used.
H2 is applied to the solenoid 14 to open the nozzle hole 11. After opening, it is only necessary to maintain the suction state of the solenoid 14 from time t2, so a lower DC voltage VL is applied to the solenoid 14 in order to save power consumption, suppress heat generation of the solenoid 14, and downsize the solenoid 14. It is said that Then, when the operation is stopped and the fire is extinguished (at time t3)
In this case, the voltage applied to the solenoid 14 is cut off, and the needle 12 is pushed back to its original position by the pressing force of the coil spring 15, so that the nozzle hole 11 is closed.

The control circuit for the solenoid 14 that controls the opening and closing of the nozzle hole 11 of such a vaporizing combustor uses a step-down transformer and a relay to step down the voltage of the AC power source, as shown in, for example, Japanese Utility Model Publication No. 4101/1983. Solenoid 14
A method of switching the voltage applied to the
There is a method of switching the applied voltage by phase control using a triac as shown in Japanese Patent No. 20. In this case, in the former method, as shown in FIG.
In the latter method, as shown in Figure 7, when the solenoid 14 is activated, the waveform of the AC power source is full-wave rectified, but when the suction is held, the waveform is half-wave rectified by phase control. It has a rectified waveform.

[0006]

[Problems to be Solved by the Invention] However, since the former method uses a step-down transformer and a relay, there are problems in that it is high in cost, requires a large amount of installation space, and is poor in reliability. Although the latter method solves these problems, since the waveform is cut after switching the voltage, there is a problem that the solenoid 14 generates electromagnetic noise. This electromagnetic noise is quite high-pitched and can be heard even from a distance of about 1 meter from the heater itself, making it extremely harsh on the ears.

The present invention was made in order to solve the above-mentioned problems, and provides a vaporization type combustor that can reduce the electromagnetic noise generated by the solenoid and realize low cost, space saving, and high reliability. The purpose is to obtain a control device for.

[0008]

[Means for Solving the Problems] In order to achieve the above object, a control device for a vaporization type combustor according to the present invention includes a solenoid that opens and closes a nozzle hole for ejecting vaporized gas of liquid fuel, and an AC power supply. Contains a rectifier circuit that rectifies DC power,
A solenoid control circuit that is controlled to apply this rectified high DC voltage when the solenoid is activated and to apply a lower DC voltage when the solenoid is attracted and held, wherein the solenoid control circuit is connected in series with the solenoid. This configuration has a transistor connected to the base of the transistor, and an oscillation circuit connected to the base of the transistor.

[0009]

[Operation] The rectifier circuit performs full-wave rectification of AC power into DC power, and when the solenoid is activated, this full-wave rectified high DC voltage is applied to the solenoid by turning on the transistor for a short time, and the needle is pressed with strong force. to open the nozzle hole. After suction, the oscillation circuit is operated at a predetermined frequency and the transistor is turned on and off in short cycles to lower the voltage applied to the solenoid and maintain the suction state, and the rectified voltage waveform is The electromagnetic noise of the solenoid is reduced because the shape is finely cut in cycles.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a control block diagram showing an embodiment of the present invention. In the figure, 20 is a microcomputer (hereinafter referred to as microcomputer) that performs overall combustion control, and only the control section of the solenoid 14 is shown here. 21 is a rectifier circuit that rectifies the AC power source 22 into a DC power source. A solenoid 14 and a transistor 23 are connected in series to this rectifier circuit 21. Further, a light receiving element 25 of a photocoupler 24 is connected to the base of the transistor 23, and a light emitting element 26 is operated by an oscillation circuit 27 built in the microcomputer 20. Further, it goes without saying that the microcomputer 20 has a built-in timer circuit (not shown) for the operation sequence. 28 is a constant voltage element that keeps the voltage applied to the light receiving element 25 constant; 29 is a solenoid 1;
A diode connected in parallel with 4 prevents a sudden voltage from being applied to the transistor 23 when the solenoid is cut off. The solenoid control circuit 30 is the rectifier circuit 21 described above.
, solenoid 14, transistor 23, photocoupler 24
, an oscillation circuit 27, a constant voltage element 28, a diode 29, and resistors 31 and 32.

The operation of this embodiment is shown in the waveform diagram in FIG. 2 and in FIG.
This will be explained with reference to the flowchart. At time t1 when preheating of the vaporizer 4 is completed, the microcomputer 20 turns on the solenoid 1.
4, a turn-on command is issued (step S1). Photocoupler 24
The output of is turned on, thus turning on the transistor 23 (step S2) and energizing the solenoid 14. This on state continues until a short period of t seconds has elapsed (step S3). Therefore, when the solenoid 14 is activated, a high DC voltage obtained by full-wave rectification of the AC power supply 22 by the rectifier circuit 21 is applied to the solenoid 14, and the needle 12 is pulled with a strong force to open the nozzle hole 11. Therefore, the vaporized gas in the vaporizer 4 is ejected from the nozzle hole 11 into the burner 10, sucks the surrounding primary air, and the mixed gas is ignited to start combustion. When t seconds have elapsed and the activation of the solenoid 14 is finished at time t2, the oscillation circuit 27 starts operating by the timer circuit in the microcomputer 20, and the output of the photocoupler 24 is turned on and off in short cycles (0.5 to 1 ms).
OFF is repeated (step S4). As a result, the transistor 23 also turns on and off repeatedly, so the solenoid 1
The waveform of the DC voltage applied to the solenoid 14 is a full-wave rectified voltage waveform cut at this short period, and the effective value is lower than that at the time of starting the solenoid, and the application of a lower DC voltage causes the solenoid 14 to The suction state is maintained, and the electromagnetic noise is extremely low. This electromagnetic noise is almost inaudible even from a distance of about 1 meter from the heater itself.

In the above embodiment, the oscillation circuit 27 is connected to the base of the transistor 23 via the photocoupler 24, but the oscillation circuit 27 may be directly connected to the base of the transistor 23.

[0013]

As described above, according to the present invention, a rectifier circuit, a solenoid, and a transistor are connected in series, and an oscillation circuit is connected to the base of the transistor. A high wave rectified DC voltage is applied, and when the solenoid is attracted and held, the oscillation output of the oscillation circuit applies a lower DC voltage obtained by finely cutting the full wave rectified voltage waveform in a short cycle. Sound is significantly reduced. Furthermore, since it can be realized using transistors, rectifier circuits, and simple oscillation circuits, it is possible to achieve low cost, space saving, and high reliability.

[Brief explanation of drawings]

FIG. 1 is a control block diagram showing one embodiment of the present invention.

FIG. 2 is a waveform diagram showing the relationship between the photocoupler output and the voltage applied to the solenoid.

FIG. 3 is a flowchart showing the operation of a solenoid.

FIG. 4 is a cross-sectional view of a conventional vaporizing combustor.

FIG. 5 is an explanatory diagram of applied voltage in a conventional solenoid control circuit.

FIG. 6 is a waveform diagram showing an example of a conventional solenoid applied voltage.

FIG. 7 is a waveform diagram showing another example of a conventional solenoid applied voltage.

[Explanation of symbols]

4. Vaporizer 10 Burner 11 Nozzle hole 12 Needle 14 Solenoid 20 Microcomputer 21 Rectifier circuit 22 AC power supply 23 Transistor 24 Photocoupler 25 Photo receiving element 26 Light emitting element 27 Oscillation circuit 28 Constant voltage element 29 Diode 30 Solenoid control circuit 31, 32 Resistance

Claims (1)

[Claims] 1. A solenoid that opens and closes a nozzle hole for ejecting vaporized gas of liquid fuel, and a high DC voltage obtained by rectifying an AC power source is applied when the solenoid is activated, and is lower than the DC voltage when the solenoid is held under suction. In a control device for a vaporizing combustor, the solenoid control circuit includes a solenoid control circuit including a rectifier circuit that is controlled to apply a DC voltage, and the solenoid control circuit includes a transistor connected in series with the solenoid, and a transistor connected in series with the solenoid. An oscillation circuit connected to a base of a vaporizer combustor.