JP3858343B2 - Control device for gas combustion equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an electromagnetic valve for closing and opening a gas supply passage in a gas combustion device .
[0002]
[Prior art]
In recent years, there has been a demand for gas combustion devices that are not only improved in safety but also reduced in size and noise.
[0003]
In terms of safety, since a gas leak is caused directly by a failure of the solenoid valve that opens and closes the gas passage and its drive circuit, the power supply method to the solenoid valve has been devised and safety measures have been taken conventionally.
[0004]
A conventional solenoid valve drive control device will be described below using a gas fan heater as an example.
[0005]
FIG. 3 shows a block diagram of the control device. In the figure, an electromagnetic valve 2 for supplying and stopping gas is provided in the middle of the gas passage 1. The gas is supplied to the combustion unit 3 through the electromagnetic valve 2. One of the coils of the solenoid valve 2 is connected to a DC 24V power source via a power supply transistor 4 and the other is connected to a circuit ground via a solenoid valve drive transistor 7 to form a solenoid valve drive circuit.
[0006]
Reference numeral 6 denotes a microcomputer (hereinafter referred to as a microcomputer). O1 of the microcomputer 6 is an output terminal of a pulse signal for controlling the supply of DC 24V power, and the frequency /
The voltage conversion circuit 5 and the switching transistor are connected to the base of the power supply transistor 4 via T.
[0007]
Further, O2 of the microcomputer 6 is an output terminal of an electromagnetic valve driving signal 9 for controlling the operation of the electromagnetic valve 2, and is connected to the base of the electromagnetic valve driving transistor 7. The collector of the solenoid valve drive transistor 7 is connected to the base of a failure detection transistor 8 that monitors the operating state of the solenoid valve drive circuit. The failure detection signal 10 is taken out from the collector of the failure detection transistor 8 and input to the input terminal i of the microcomputer 6. Connect and return.
[0008]
FIG. 4 shows a timing chart of the solenoid valve drive signal 9 and the failure detection signal 10. The solenoid valve drive signal 9 is a pulse signal having a constant period in which the on-time t1 and the off-time t2 are equal. In this example, the frequency is 80 Hz, the on-time t1 = off-time t2 = 6.25 mS (duty ratio 50.0%). Signals are shown. The failure detection signal 10 indicates a signal waveform when the power supply transistor 4, the solenoid valve 2, and the solenoid valve drive transistor 7 are electrically connected normally, and a signal having the same logic as that of the solenoid valve drive signal 9 is detected. The
[0009]
In such a configuration, when the equipment is burned from the stop, the microcomputer 6 first outputs a pulse signal from O1, turns on the power supply transistor 4 via the frequency / voltage conversion circuit 5, and supplies DC 24V power. To do. Next, a solenoid valve drive signal 9 is output from O 2 to open the solenoid valve 2 and supply gas to the combustion section 3.
[0010]
Here, since the solenoid valve drive signal 9 is a pulse signal, the solenoid valve drive transistor 7 performs switching, and power is supplied only intermittently to the solenoid valve 2, but the solenoid valve 2 has a frequency of about 100 Hz. The valve body of the solenoid valve 2 is not detached by the holding force and is not closed, and the gas can be continuously supplied.
[0011]
The microcomputer 6 outputs the solenoid valve drive signal 9 and simultaneously monitors the failure detection signal 10. When the solenoid valve drive circuit is normal, the signal output from O1 at the timings t1 and t2. Since the logic logic and the signal logic input to i are expected to be equal, the microcomputer 6 can determine this and monitor the state of the solenoid valve drive circuit at all times.
[0012]
For example, at the on-time t1 of the solenoid valve drive signal 9, if the solenoid valve drive transistor 7 is open failure (failure that gas is stopped), the failure detection signal 10 is turned off and becomes an inverse value. Further, at the off time t2 of the solenoid valve drive signal 9, if the solenoid valve drive transistor 7 is short-circuited (failed to leak gas), the failure detection signal 10 is turned on and becomes an inverse value.
[0013]
The microcomputer 6 determines that the reverse logic = failure, stops the power supply to the solenoid valve 2, and closes the gas supply passage. When the solenoid valve drive signal 9 is operated while being always on (DC signal), the latter short-circuit failure (failure that causes gas leakage) cannot be detected at all times, and safety is lowered.
[0014]
Thus, by using a pulse signal to control the power supply to the solenoid valve 2, it is possible to always detect both open and short modes of the solenoid valve drive circuit, thereby improving safety.
[0015]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, the electromagnetic valve 2 is pulse-driven in order to detect a failure, so that the power supply to the electromagnetic valve 2 is halved in time and the power supply efficiency is deteriorated.
[0016]
In order to obtain the same electromagnetic force in the solenoid valve 2 when the solenoid valve 2 is driven by a DC signal, it is necessary to double the drive voltage or double the number of turns of the solenoid valve coil. However, increasing the drive voltage leads to an increase in power consumption loss of the entire system circuit, and increasing the number of coil turns leads to an increase in the size of the solenoid valve 2.
[0017]
Further, when the solenoid valve 2 opens, a collision sound between the plunger and the solenoid valve body is generated. Quiet countermeasures can be achieved by providing a cushioning material between the plunger and the solenoid valve body, but with the same electromagnetic force, the release voltage at which the valve body closes increases, and the number of coil turns must be increased to increase the electromagnetic force. There is. That is, noise reduction of the solenoid valve 2 means an increase in size of the solenoid valve 2. Or, in the drive circuit, it is necessary to take measures by increasing the drive voltage or making the drive signal DC. There are issues such as.
[0018]
Accordingly, an object of the present invention is to ensure the same safety as that of the prior art and to realize miniaturization and noise reduction of the solenoid valve.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an electromagnetic valve connected in the middle of a gas passage for supplying and stopping gas reaching the combustion section, and one of the coils in the electromagnetic valve is connected to a DC power source via a power supply transistor. And the other is connected to the base of the power supply transistor via a frequency / voltage conversion circuit and a switching transistor, and the DC power supply A microcomputer having a first output terminal for outputting a pulse signal for controlling the supply of the first output terminal and a second output terminal connected to the base of the solenoid valve drive transistor for outputting a solenoid valve drive signal for controlling the operation of the solenoid valve; And a collector of the solenoid valve drive transistor includes a failure detection transistor for monitoring an operation state of the solenoid valve drive circuit. The base of the register is connected, the failure detection signal is taken out from the collector of the failure detection transistor, connected to the input terminal of the microcomputer and fed back, and the solenoid valve drive signal is a pulse signal with a constant cycle. The on-time is set to be significantly larger than the off-time .
[0020]
According to the above invention, since the solenoid valve is driven with a pulse signal to detect a failure, the same safety as the conventional configuration can be realized, and the ratio of the pulse signal power supply time to the solenoid valve with respect to the stop time is sufficient. Since it is large, electromagnetic force can be obtained efficiently, the number of coil turns can be reduced, and the solenoid valve can be miniaturized. Moreover, the noise reduction countermeasure by the buffer material can be realized with the conventional number of coil turns.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, an electromagnetic valve that is connected in the middle of a gas passage to supply and stop gas to the combustion section, and one of the coils in the electromagnetic valve is connected to a DC power source through a power supply transistor, and the other is A solenoid valve drive circuit connected to circuit ground via a solenoid valve drive transistor, and a pulse signal connected to the base of the power supply transistor via a frequency / voltage conversion circuit and a switching transistor to control the supply of the DC power supply And a microcomputer having a second output terminal connected to the base of the solenoid valve driving transistor and outputting a solenoid valve drive signal for controlling the operation of the solenoid valve. The collector of the drive transistor is connected to the base of a failure detection transistor that monitors the operating state of the solenoid valve drive circuit. The failure detection signal is taken out from the collector of the failure detection transistor, connected to the input terminal of the microcomputer, and fed back, and the solenoid valve drive signal is a pulse signal with a constant period, and the on time is the off time. Is set to be significantly larger .
[0022]
Since the electromagnetic valve is driven by a pulse signal to detect a failure, it is possible to detect a failure of the electromagnetic valve drive circuit open or short, so that conventional safety can be ensured. In addition, since the ratio of the pulse signal power supply time to the stop time is sufficiently large, the electromagnetic force can be obtained efficiently, the number of coil turns can be reduced, and the solenoid valve can be downsized. In addition, when the electromagnetic valve is silenced, the electromagnetic valve can be silenced without increasing the size of the coil by supplementing the electromagnetic force with the power supply efficiency.
[0023]
Embodiments of the present invention will be described below with reference to FIGS.
[0024]
(Example 1)
FIG. 1 shows a block diagram of a control apparatus of the present invention. An electromagnetic valve 12 for supplying and stopping gas is provided in the middle of the gas passage 11. The gas is supplied to the combustion unit 13 via the electromagnetic valve 12. One of the coils of the solenoid valve 12 is connected to a DC 24V power source via a power supply transistor 14 and the other is connected to a circuit ground via a solenoid valve drive transistor 17 to form a solenoid valve drive circuit.
[0025]
Reference numeral 16 denotes a microcomputer (hereinafter referred to as a microcomputer). O1 of the microcomputer 16 is an output terminal of a pulse signal for controlling supply of DC 24V power, and is connected to the base of the power supply transistor 14 through the frequency / voltage conversion circuit 15 and a switching transistor .
[0026]
Further, O2 of the microcomputer 16 is an output terminal of an electromagnetic valve driving signal 19 for controlling the operation of the electromagnetic valve 12, and is connected to the base of the electromagnetic valve driving transistor 17. The collector of the solenoid valve drive transistor 17 is connected to the base of a failure detection transistor 18 that monitors the operating state of the solenoid valve drive circuit. The failure detection signal 20 is taken out from the collector of the failure detection transistor 18 and input to the input terminal i of the microcomputer 16. Connect and return.
[0027]
FIG. 2 shows a timing chart of the solenoid valve drive signal 19 and the failure detection signal 20. The electromagnetic valve drive signal 19 is a pulse signal having a fixed period, and the on time t3 and the off time t4 are significantly different, and the relation of on time t3> off time t4 is satisfied.
[0028]
In this embodiment, a signal having a frequency of 80 Hz, an on time t3 = 12.4 mS, and an off time t4 = 0.1 mS (duty ratio 99.2%) is shown. The reason why the ON time is sufficiently long is to improve the power supply efficiency to the solenoid valve 12.
[0029]
The failure detection signal 20 is a signal obtained as a result of the switching operation of the solenoid valve drive transistor 17 and the failure detection transistor 18 by the solenoid valve drive signal 19.
[0030]
This figure shows signal waveforms when the power supply transistor 14, the solenoid valve 12, and the solenoid valve drive transistor 17 are electrically connected normally, and a signal having the same logic as the solenoid valve drive signal is detected.
[0031]
Although the power supply efficiency increases as the OFF time t4 of the solenoid valve drive signal 19 is shorter, it is necessary to secure at least the switching time of the two transistors 17 and 18 in order to form a failure detection signal. In general, the switching time of a transistor is several tens of μs, and is 0.1 m (= 100 μs) S in consideration of variation and a safety factor.
[0032]
Further, by using a transistor having a fast switching operation, the off time t4 can be further shortened, and the duty ratio can be improved.
[0033]
Next, the operation and action will be described. When the device is burned from the stop, the microcomputer 6 first outputs a pulse signal from O1, turns on the power supply transistor 14 via the frequency / voltage conversion circuit 15, and DC24V Supply power.
[0034]
Next, the solenoid valve drive signal 19 is output from O2, the solenoid valve 12 is opened, and gas is supplied to the combustion unit 3.
[0035]
Here, since the duty ratio of the electromagnetic valve drive signal 19 increases to 99.2% at the same frequency as the conventional drive signal, the power supply efficiency to the electromagnetic valve 12 is sufficiently improved.
[0036]
Although it is pulse drive, the solenoid valve 12 can be operated with a margin and gas can be supplied without any problem.
[0037]
Further, since the off time t4 is sufficiently short, the voltage with which the solenoid valve 12 is released from the open state can be improved even with the same holding force.
[0038]
If the same solenoid valve 12 as that of the conventional configuration is used, not only the solenoid valve driving condition is provided, but also the driving voltage of the solenoid valve 12 can be lowered.
[0039]
In addition, the design conditions of the solenoid valve 12 are eased. For example, the number of turns of the coil can be reduced, the coil wire diameter can be reduced, and the size of the coil can be reduced. Alternatively, it is possible to reduce the noise of the electromagnetic valve 12 by providing an impact buffer on the plunger of the electromagnetic valve 12. This is because even if the operating conditions of the solenoid valve 12 are stricter, there is a margin on the solenoid valve drive circuit side than before.
[0040]
Similarly to the conventional configuration, the microcomputer 16 outputs the solenoid valve drive signal 19 and simultaneously monitors the failure detection signal 20. When the solenoid valve drive circuit is normal, at each timing t3 and t4, Since the signal logic output from O1 is expected to be the same as the signal logic input to i, the microcomputer 6 determines the match / mismatch and constantly monitors the normal state and abnormal state of the solenoid valve drive circuit, When an abnormality occurs, the supply of DC 24V can be stopped to shut off the gas.
[0041]
In this embodiment, the solenoid valve drive signal 19 has a 12.5 mS cycle. However, if the cycle (t3 + t4) is increased to 1000 mS and the off time t4 is kept at 0.1 mS, the duty ratio is further improved. Will be. The optimum cycle is determined in relation to the designed solenoid valve. However, since the period of the electromagnetic valve drive signal 19 is a sampling period for failure detection, it should be a time that does not hinder the detection when a failure occurs.
[0042]
【The invention's effect】
As described above, according to the present invention, since the power supply to the solenoid valve is controlled using the pulse signal, the failure of the solenoid valve drive circuit can be detected, and the same safety as the conventional one can be ensured. And, since the pulse signal has a feature that the ratio of the power supply time to the power stop time is sufficiently large, the power supply efficiency to the solenoid valve is good, and the design conditions of the solenoid valve can be relaxed, It is possible to reduce the size of the solenoid valve by reducing the number of coil turns, and to implement countermeasures to reduce the noise of the solenoid valve, which is effective in reducing the size of the gas equipment and reducing the noise.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control device for a gas combustion device showing Embodiment 1 of the present invention. FIG. 2 is a timing chart of control signals of the control device. FIG. 3 is a block diagram of a control device for a conventional gas combustion device . Fig. 4 Timing chart of control signal of the same control device
11 Gas supply passage 12 Solenoid valve 16 Microcomputer 17 Solenoid valve drive transistor 18 Failure detection transistor 19 Solenoid valve drive signal

Claims (1)

An electromagnetic valve connected in the middle of the gas passage for supplying and stopping gas reaching the combustion section, one of the coils in the electromagnetic valve is connected to a DC power source via a power supply transistor, and the other is an electromagnetic valve driving transistor A solenoid valve driving circuit connected to the circuit ground via the first, a frequency / voltage conversion circuit, and a switching transistor connected to the base of the power supply transistor to output a pulse signal for controlling the supply of the DC power. And a microcomputer having a second output terminal connected to the output terminal of the first output terminal and the base of the solenoid valve drive transistor and outputting a solenoid valve drive signal for controlling the operation of the solenoid valve, the collector of the solenoid valve drive transistor Connect the base of the failure detection transistor to monitor the operating state of the solenoid valve drive circuit, this failure The failure detection signal is taken out from the collector of the output transistor, connected to the input terminal of the microcomputer, and fed back. Control device for gas combustion equipment set to a significantly large value.

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