JPH033804Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion control device for a gas burner used as a heat source for water heaters and the like.

Conventionally, thermocouples have been used as sensors to detect combustion in this type of gas burner, but since such thermocouples have a large heat capacity, response is a problem, and conventional sensors using thermocouples have poor response. In order to improve performance, the combustion of the gas burner is controlled by detecting the output gradient of the thermocouple. That is, ignition of the gas burner is detected and controlled by the output rising slope of the thermocouple, and extinguishing is detected and controlled by the output falling slope. However, since detection of such a slope detects even momentary fluctuations of the combustion flame, ignition detection based on the output rising slope is effective, but extinguishing detection using the output falling slope may cause malfunction, It is preferable to detect it by a voltage drop. However, if a drop in the output voltage is detected in this way, the following problems arise. In other words, in the combustion control device of a gas burner, the quality of the load control element, such as a transistor for driving a relay, is judged for a certain period of time before combustion starts (pre-check), but unlike an instantaneous water heater, water supply is resumed in a very short time. in case of,
As shown in Figure 1, the output voltage does not drop rapidly to the reference output due to poor responsiveness of the thermocouple, so it is determined that the load control element is abnormal because the control element is in the driving state due to the signal from the flame detection circuit during pre-check. Therefore, it was not possible to use t1 for a certain period of time, making it inconvenient to use.

The present invention is intended to solve the above-mentioned conventional problems, and will be specifically explained below based on an embodiment shown in the drawings.

FIG. 2 is a control circuit diagram showing an embodiment of the present invention, where 1 is a gas burner and 2 is an electromagnetic valve for controlling the supply of gas to the gas burner 1. Reference numeral 3 denotes a thermocouple, and the thermocouple 3 is connected to a flame detection circuit 4 which amplifies its output and determines that the ignition is ignited at a constant output rising slope, and that the flame is extinguished when the output falls below a reference output. Reference numeral 5 denotes a combustion control circuit that controls the solenoid valve 2, an igniter (not shown), etc., which judges the quality of the load control element for a certain period of time by turning on the operation switch 6, and then drives the igniter and solenoid valve 2 if there is no abnormality. If the ignition signal is inputted by the signal from the flame detection circuit 4 after the ignition operation, steady combustion is performed, and if the ignition signal is not inputted within a certain period of time, it is assumed that the ignition is defective and the operation is shifted to safe operation. It is designed to do so. Also, even during steady combustion, if the output voltage of the thermocouple 3 drops below the set voltage in response to the output from the flame detection circuit 4, it is determined that the flame is extinguished midway, and safe operation is performed to prevent the release of raw gas. . 7 is the flame detection circuit 4
A switching element installed in the power supply circuit of the operation switch 6.
The circuit is closed after the pre-check operation of the control circuit 5 is completed by turning on the switch, and the circuit is opened in synchronization with the opening of the operation switch 6. If the operating switch 6 is applied to a water heater, a water switch that detects water flow may be used, and the switching element 7 may be a transistor.

In the above configuration, during steady combustion, the output voltage of the thermocouple 3 increases to the reference output as shown in FIG. 3, and the closing element 7 closes the circuit during this time. Next, when combustion is stopped, the switching element 7 also opens the circuit in synchronization with the operation switch 6, and the output voltage of the thermocouple 3 gradually decreases due to cooling. When the operation switch 6 is turned on to restart combustion in a very short time after the combustion has stopped, the closing of the opening/closing element 7 is delayed for a pre-check time, so the control circuit 5 from the flame detection circuit 4 outputs an output during that time. is cut off and output to the control circuit 5 after the pre-check is completed.
Therefore, even if the stop time is short enough for the output of the thermocouple 3 to fall below the reference output, combustion can be restarted without a safe operation.

Therefore, as described above, the present invention is designed to cut off the flame detection power of the pre-check flame detection circuit from the time the operation switch is turned on, so that even if combustion is resumed after a very short pause, combustion will not be possible. There is no situation,
When the combustion control device for a gas burner according to the present invention is used in a water heater, hot water supply can be resumed in an extremely short time, and the usability is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is an output voltage waveform diagram of a thermocouple in a conventional example, FIG. 2 is a control circuit diagram showing an embodiment of the present invention, and FIG. 3 is an output voltage waveform diagram of a thermocouple in the same example. 3...Thermocouple, 4...Flame detection circuit, 5...Control circuit, 6...Operation switch.

Claims (1)

[Scope of utility model registration request] A thermocouple that generates output from the combustion flame, a flame detection circuit that outputs an extinguishing signal when the output drops below a reference output, and a flame detection circuit that performs an ignition operation after performing a pre-check when the operation switch is turned on. and a control circuit in which combustion is controlled by the flame detection output of the flame detection circuit, the power supply circuit of the flame detection circuit is configured to open the circuit when the operation switch is opened, and close the circuit after a pre-check time has elapsed when the operation switch is turned on. A combustion control device for a gas burner, characterized in that it is provided with a switching element.