JP5378947B2 - Gas combustion equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas combustion device capable of enhancing reliability of correspondence to accidental fire of a burner. <P>SOLUTION: The gas combustion device includes a means 24 for corresponding/confirming the accidental fire. When the burner 1 is in a fire extinguishing state, the means 24 carries out control for forcibly starting a monitoring circuit 33 by a means 22 for forcibly starting the monitoring circuit, if a level of a detection signal of a thermocouple 6 is equal to or lower than a second accidental fire determination value, so as to execute a first accidental fire corresponding/confirming processing for detecting whether a transistor 31 becomes an OFF state of not. If the level of the detection signal of the thermocouple 6 is over the second accidental fire determination value, the means 24 carries out control for turning off the transistor 31 by a forcible off-control means 23 so as to execute a second accidental fire corresponding/confirming processing for detecting whether the transistor 31 becomes the OFF state of not. If the OFF state of the transistor 31 is not detected, the means 24 prohibits ignition processing of the burner 1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a gas combustion apparatus having a function of monitoring a combustion state of a burner with a thermocouple.

  Conventionally, in a gas combustion apparatus that is provided with a thermocouple provided in the vicinity of a burner to detect the combustion state of the burner and whose operation is controlled by a microcomputer, it operates independently of the microcomputer and is operated by a thermocouple. What is equipped with the monitoring circuit which monitors the combustion state of a burner is known (for example, refer patent document 1).

  This monitoring circuit is activated after the ignition process of the burner by the microcomputer, and monitors the combustion state of the burner by the detection signal of the thermocouple. When a burner misfire is detected due to a decrease in the level of the thermocouple detection signal, the transistor connected between the power supply coil of the solenoid valve provided in the gas supply pipe for supplying the fuel gas to the burner and its power supply is turned off. In this state, the solenoid valve is closed and the supply of fuel gas to the burner is stopped.

  During combustion of the burner, based on the detection signal of the thermocouple, monitoring of the combustion state of the burner by the microcomputer and monitoring of the combustion state of the burner by the monitoring circuit are executed in parallel. Therefore, even if the microcomputer fails during combustion of the burner, the supply of fuel gas to the burner can be stopped by the monitoring circuit when the misfire of the burner occurs.

  However, if the microcomputer is ignited and the combustion operation of the burner is started while the monitoring circuit is broken, if the microcomputer fails during the burner combustion, The supply of fuel gas cannot be stopped.

  Therefore, in the gas combustion apparatus described in Patent Document 1, when the ignition operation of the burner is performed by the user, the monitor circuit is forcibly activated before the ignition process of the burner by the microcomputer is executed. Whether or not the transistor is turned off is confirmed, and when it is not confirmed that the transistor is turned off, the ignition process of the burner is prohibited.

JP 2004-93047 A

  When a thermocouple is used as an element for detecting the burner combustion state, the response speed to the temperature change is slow, so even if the burner is extinguished, until the thermocouple detection signal level becomes lower than the misfire detection level, Takes time.

  For this reason, when the burner is ignited immediately after extinguishing the burner, the level of the thermocouple detection signal is higher than the misfire detection level, and the solenoid valve may not be closed even when the monitoring circuit is activated. In this case, since the operation of the monitoring circuit cannot be confirmed before the burner is ignited, the reliability for misfire is reduced.

  This invention is made | formed in view of this background, and it aims at providing the gas combustion apparatus which can improve the reliability with respect to the misfire of a burner.

  The present invention has been made to achieve the above object, and includes a burner, a gas supply pipe for supplying fuel gas to the burner, an electromagnetic valve for opening and closing the gas supply pipe, a power source, and driving of the electromagnetic valve. Switching means connected between the coils, a thermocouple for detecting the burner combustion state, and performing the ignition process of the burner, and when detecting misfire of the burner from the detection signal of the thermocouple, Combustion control means for controlling to turn off the switching means, and the switching when the level of the detection signal of the thermocouple becomes equal to or lower than a first misfire determination value when activated after the burner ignition processing is performed. The present invention relates to a gas combustion apparatus including a monitoring circuit that performs control to turn off the means.

  A switching state detecting unit for detecting whether the switching unit is in an on state or an off state; and a monitoring circuit forcible starting unit for performing control to start the monitoring circuit regardless of whether or not the burner is ignited. And a forced-off control means for performing control to turn off the switching means regardless of the operation of the monitoring circuit; and when the burner is in a fire extinguishing state, the level of the detection signal of the thermocouple is the first misfire. It is determined whether or not the second misfire determination value set below the determination value, and when the level of the detection signal of the thermocouple is equal to or lower than the second misfire determination value, the monitoring circuit forced start means A first misfire pair that performs control to activate the monitoring circuit and determines whether or not the switching means is detected to be off by the switching state detection means. When the confirmation process is executed and the level of the detection signal of the thermocouple exceeds the second misfire determination value, the switching means is controlled to be turned off by the forced-off means, and the switching state detection means is used to In the first misfire correspondence confirmation process or the second misfire correspondence confirmation process, a second misfire correspondence confirmation process for determining whether or not the switching means is detected to be in an off state is executed, and the switching And a misfire countermeasure checking means for prohibiting the ignition process of the burner when the means is not detected to be in an off state.

  According to the present invention, when the burner is in a fire extinguishing state, the misfire countermeasure confirmation means confirms whether the detection signal level of the thermocouple is equal to or lower than the second misfire determination value. When the level of the detection signal of the thermocouple is equal to or lower than the second misfire determination value (it is assumed that a certain time has passed since the burner was extinguished), the first misfire response When the confirmation process is executed and the level of the detection signal of the thermocouple exceeds the second misfire determination value (it is assumed that the elapsed time after the burner is extinguished is short), the second A misfire response confirmation process is executed.

  Here, when the level of the detection signal of the thermocouple is equal to or less than the second misfire determination value, the monitoring circuit is forcibly started by the first misfire correspondence confirmation process, It can be confirmed whether or not both the switching means operate normally.

  On the other hand, when the level of the detection signal of the thermocouple exceeds the second misfire determination value, even if the monitoring circuit is forcibly started, the switching means is not controlled to be turned off by the monitoring circuit. The operation of the circuit and the switching means cannot be confirmed. Therefore, in this case, it is possible to confirm whether or not the switching means operates normally by performing control to forcibly turn off the switching means by the second misfire countermeasure confirmation processing.

  Thus, according to the present invention, even when the level of the detection signal of the thermocouple exceeds the second misfire determination value, the second misfire countermeasure confirmation process is executed by the misfire countermeasure confirmation means. Thus, the operation of the switching means is confirmed. In this case, when the burner is ignited immediately after the burner is extinguished, the ignition process is executed on condition that the switching means operates normally. The reliability of misfire can be improved compared with the case where only the operation is performed.

The block diagram of the gas combustion apparatus of this invention. The block diagram of the controller of a gas combustion apparatus. The flowchart of the operation check of the monitoring circuit and the relay power supply transistor.

  Embodiments of the present invention will be described with reference to FIGS.

  Referring to FIG. 1, the gas combustion apparatus of the present embodiment is a gas fan heater, and this gas fan heater is provided in burner 1, gas supply pipe 2 for supplying fuel gas to burner 1, and gas supply pipe 2. The first electromagnetic valve 3 and the second electromagnetic valve 4 that open and close the gas supply pipe 2, the proportional valve 5 that adjusts the amount of combustion of the burner 1 by changing the opening of the gas supply pipe 2, and the vicinity of the burner 1. And a thermocouple 6 for detecting the combustion state of the burner 1 and a controller 10 for controlling the overall operation of the gas fan heater.

  The drive coils of the first solenoid valve 3 and the second solenoid valve 4 are connected to a rectifier circuit 7, and the rectifier circuit 7 is connected to a commercial AC power supply 8 via a relay switch 12a and a relay switch 13a provided in the controller 10. ing. With this configuration, when both the relay switch 12a and the relay switch 13a are turned on (conductive state), power is supplied from the commercial AC power supply 8 to the rectifier circuit 7, and the first electromagnetic valve 3 and the second electromagnetic valve 4 are The valve opens.

  Next, the configuration of the controller 10 will be described with reference to FIG. The controller 10 is an electronic circuit unit composed of a microcomputer 20 (hereinafter referred to as a microcomputer 20). The microcomputer 20 causes the microcomputer 20 to execute a control program for the gas fan heater, whereby the microcomputer 20 includes combustion control means 21, It functions as the monitoring circuit forced activation means 22, the forced off control means 23, and the misfire response confirmation means 24.

  The controller 10 also includes a transistor 31 (corresponding to the switching means of the present invention) connected between the drive coil 12 b of the first relay 12 and the drive coil 13 b of the second relay 13 and the power source, and the base of the transistor 31. A transistor drive circuit 32 connected to drive the transistor 31 on / off; a switching state detection circuit 30 that detects the on / off state of the transistor 31; a first relay drive circuit 38 that switches the first relay 12 on / off; A second relay drive circuit 39 for switching on / off of the second relay 13, a first relay answer circuit 36 for detecting the on / off state of the first relay 12, and a second relay for detecting the on / off state of the second relay 13. The outputs of the answer circuit 37, the first relay answer circuit 36 and the second relay answer circuit 37 A relay answer-on circuit 35 that is in a relay-on detection state; a flame detection circuit 34 that is connected to the thermocouple 6 and outputs a flame detection signal Fs (a thermocouple detection signal) corresponding to the combustion state of the burner 6; A monitoring circuit 33 for monitoring the combustion state of the burner 1 by the flame detection signal Fs during the combustion operation of the burner 1 is provided.

  The switching state detection circuit 30 is connected to the input port Pi1 of the microcomputer 20 and detects from the collector potential of the transistor 31 whether the transistor 31 is on (conducting) or off (cut off). The level of the switching detection signal Tr_ans is set to High when the transistor 31 is on, and the level of the switching detection signal Tr_ans is set to Low when the transistor 31 is off.

  The transistor drive circuit 32 is connected to the output port Po1 and the monitoring circuit 33 of the microcomputer 20, and when the forced off signal (Tr_off2) is output from Po1, and the misfire off signal (Tr_off1) is output from the monitoring circuit 33. The transistor 31 is turned off by setting the output to the base of the transistor 31 to the high level. When neither the forced-off signal (Tr_off1) nor the misfire-off signal (Tr_off2) is output, the transistor drive circuit 32 sets the output to the base of the transistor 31 to a low level to turn on the transistor 31.

  The flame detection signal Fs output from the flame detection circuit 34 is an analog signal and is input to the AD input (analog / digital conversion input) port ADi and the monitoring circuit 33 of the microcomputer 20.

  The first relay drive circuit 38 is connected to the output port Po3 of the microcomputer 20, and when the first relay on signal (R1_on) is output from Po3, the output of the first relay 12 with respect to the coil 12b is set to Low. Is turned on (the relay switch 12a is turned on). When the first relay on signal (R1_on) is not output from Po3, the first relay drive circuit 38 sets the output to the coil 12b of the first relay 12 to High and turns off the first relay 12 (cuts off the relay switch 12a). State).

  The first relay answer circuit 36 outputs the first relay answer signal R1_ans when the first relay 12 is in an ON state (in this case, the input to the first relay answer circuit 36 becomes approximately 0V). In addition, when the first relay 12 is in an OFF state (in this case, the input to the first relay answer circuit 36 is almost the power supply voltage), the first relay answer circuit 36 receives the first relay answer signal R1_ans. Stop output.

  The second relay drive circuit 39 is connected to the output port Po4 of the microcomputer 20, and when the second relay on signal (R2_on) is output from Po4, the output to the coil 13b of the second relay 13 is set to Low and the second relay 13 Is turned on (the relay switch 13a is turned on). When the second relay ON signal (R2_on) is not output from Po4, the second relay drive circuit 39 sets the output to the coil 13b of the second relay 13 to High and turns off the second relay 13 (cuts off the relay switch 13a). State).

  The second relay answer circuit 37 outputs the second relay answer signal R2_ans when the second relay 13 is in an ON state (in this case, the input to the second relay answer circuit 37 becomes approximately 0V). Further, when the second relay 13 is in an off state (in this case, the input to the second relay answer circuit 37 is almost the power supply voltage), the second relay answer circuit 37 receives the second relay answer signal R2_ans. Stop output.

  The relay answer-on circuit 35 is connected to the output port Po2 of the microcomputer 20, and when the relay answer-on signal (Ra_on) is output from Po2, the first relay answer signal (R1_ans) is sent to the first relay answer circuit 36. ) And an instruction signal (R2_f) for outputting the second relay answer signal (R2_ans) to the second relay answer circuit 37.

  In the monitoring circuit 33, the first relay 12 and the second relay 13 are turned on in accordance with the ignition process of the burner 1 by the combustion control means 21, and the first relay answer signal R1_ans is input from the first relay answer circuit 36. When the second relay answer signal R2_ans is input from the second relay answer circuit 37, a predetermined time (set slightly longer than the time required for the burner 1 ignition process) has elapsed.

  When the operation starts, the monitoring circuit 33 determines whether or not the level of the flame detection signal (Fs) is equal to or lower than a first misfire determination value (for example, set to about 8 mV ± 3 mV). When the level of the flame detection signal (Fs) exceeds the first misfire determination value (determined that the burner 1 has not misfired), the output to the base of the transistor 31 is set to the low level (0 V). Then, the transistor 31 is turned on. Thereby, the combustion operation of the burner 1 is continued.

  On the other hand, when the level of the flame detection signal (Fs) becomes equal to or lower than the first misfire determination value (when the misfire of the burner 1 occurs), the monitoring circuit 33 sets the output to the base of the transistor 31 to High, The transistor 31 is turned off. As a result, energization of the drive coil 12b of the first relay 12 and the drive coil 13b of the second relay 13 is interrupted, and both the first relay 12 and the second relay 13 are turned off, and the first solenoid valve 3 and the second solenoid valve 3 are turned off. Both solenoid valves 4 are closed. Then, the supply of fuel gas from the gas supply pipe 2 to the burner 1 is interrupted.

  The combustion control means 21 outputs a first relay drive signal (R1_on) from the output port Po3 to the first relay drive circuit 38 when the user performs an operation to start the operation of the gas fan heater, and the first relay 12 is turned on. At the same time, the second relay drive signal (R2_on) is output from the output port Po4 to the second relay drive circuit 39, the second relay 13 is turned on, the ignition process of the burner 1 is performed, and the combustion operation of the burner 1 is performed. Start.

  The combustion control means 21 monitors the level of the flame detection signal (Fs) input to the AD input port ADi during the combustion operation of the burner 1, and the level of the flame detection signal (Fs) is equal to or less than the first misfire determination value. When this happens, the output of the first relay drive signal (R1_on) from the output port Po3 and the output of the second relay drive signal (R2_on) from the output port Po4 are stopped. Thus, the combustion control means 21 turns off the first relay 12 and the second relay 13 to close the first electromagnetic valve 3 and the second electromagnetic valve 4, and stops the supply of fuel gas to the burner 1.

  The monitoring circuit forced activation means 22 outputs a relay answer-on signal (Ra_on) from the output port Po2 to the relay answer-on circuit 35, and sends a first relay answer signal (R1_ans) from the first relay answer circuit 36 to the monitoring circuit 33. In addition, the second relay answer signal (R2_ans) is output from the second relay answer circuit 37 to the monitoring circuit 33. Thus, the monitoring circuit forced activation means 22 performs control to forcibly activate the monitoring circuit 33 regardless of whether the first relay 12 and the second relay 13 are on or off.

  The forced off control means 23 outputs a forced off signal (Tr_off2) from the output port Po1 to the transistor drive circuit 32, and turns off the transistor 31 regardless of whether or not the misfire off signal (Tr_off1) is output from the monitoring circuit 33. Control.

  Next, according to the flowchart shown in FIG. The misfire correspondence checking means 24 performs the processing according to the flowchart of FIG. 3 when the burner 1 is in the fire extinguishing state.

  The misfire correspondence checking means 24 is at STEP 1 the level of the flame detection signal Fs input to the AD input port ADi is equal to or lower than the second misfire determination value (2 mV) set to be equal to or lower than the first misfire determination value (8 mV). Determine whether or not.

  Then, when the level of the flame detection signal Fs is equal to or lower than the second misfire determination value, the process proceeds to STEP 2, and the misfire response confirmation means 24 activates the monitoring circuit 33 by the monitoring circuit forced activation means 22. In this case, since the level of the flame detection signal (Fs) is lower than the first misfire determination value in the monitoring circuit 33, if the monitoring circuit 33 operates normally, the misfire off signal (Tr_off1) is sent from the monitoring circuit 33 to the transistor drive circuit 32. ) Is output, and the output level from the transistor drive circuit 32 to the base of the transistor 31 becomes High.

  Therefore, if the transistor 31 is operating normally, the transistor 31 is turned off, and the level of the switching detection signal (Tr_ans) output from the switching state detection circuit 30 to the input port Pi1 of the microcomputer 20 is reduced. It becomes Low indicating the detection result that it is in a state.

  On the other hand, when the level of the flame detection signal Fs exceeds the second misfire determination value (2 mV) in STEP1, the process proceeds to STEP10. Here, if the level of the flame detection signal Fs exceeds the second misfire determination value 2 mV and further exceeds the first misfire determination value (8 mV), the misfire off signal (Tr_off1) is sent from the monitoring circuit 33 to the transistor drive circuit 32. The transistor 31 is kept on without being output. For this reason, the transistor 31 cannot be turned off by the operation of the monitoring circuit 33.

  Therefore, the misfire correspondence checking means 24 outputs a forced off signal (Tr_off2) from the output port Po1 to the transistor drive circuit 32 in STEP10. As a result, the output from the transistor drive circuit 32 to the base of the transistor 31 becomes High. Therefore, if the transistor 31 is operating normally, the transistor 31 is turned off, and the switching detection signal (Tr_ans) output from the relay power answering circuit 30 indicates the detection result that the transistor 31 is turned off. Low.

  In STEP3 following STEP2 and STEP10, the misfire handling confirmation means 24 determines whether or not the switching detection signal (Tr_ans) is Low. Here, when the monitoring circuit activation signal (Ra_on) is output in STEP 2 and the switching detection signal (Tr_ans) becomes Low, it can be determined that the monitoring circuit 33 and the transistor 31 are operating normally. .

  When the control for forcibly turning off the transistor 31 is performed in STEP 10, when the switching detection signal (Tr_ans) becomes Low indicating the detection result that the transistor 31 is off, the transistor 31 is normally operated. It can be determined that it is operating. Therefore, when the switching detection signal (Tr_ans) is low at STEP3, the process proceeds to STEP4, and the misfire correspondence checking means 24 ends the forced operation of the monitoring circuit 33, and ends the forced off of the transistor 31 at STEP5. Proceed to to end the process.

  In this case, the burner 1 can be ignited by the combustion control means 21 and the burner 1 can be burned.

  On the other hand, when the control for forcibly starting the monitoring circuit is performed in STEP 2 and the level of the switching detection signal (Tr_ans) input to the input port Pi1 is High in STEP 3, the monitoring circuit 33 and the transistor drive circuit It can be determined that at least one of 32 and transistor 31 is out of order. Note that the processing for forcibly starting the monitoring circuit 33 by the processing of STEP2 and STEP3 to determine whether or not the transistor 31 is turned off corresponds to the first misfire handling confirmation processing of the present invention. To do.

  When the transistor 31 is forcibly turned off in STEP 10 and the output of the transistor detection signal (Tr_ans) becomes High in STEP 3, at least one of the transistor drive circuit 32 and the transistor 31 is used. Can be determined to be malfunctioning. Note that the processing for forcibly turning off the transistor 31 by the processing in STEP 10 and STEP 3 to determine whether or not the transistor 31 is turned off corresponds to the second misfire countermeasure confirmation processing of the present invention. .

  Therefore, when the switching detection signal (Tr_ans) becomes High in STEP3, the process branches to STEP11, and the misfire handling confirmation means 24 performs a display for notifying abnormality on a display unit (not shown). Further, in subsequent STEP 12, the misfire response checking means 24 prohibits the ignition process of the burner 1 by the combustion control means 21.

  As a result, when the burner 1 is misfired, the combustion operation of the gas fan heater is prevented from being started in a state in which it is impossible to stop the supply of fuel gas to the burner 1 by turning off the transistor 31. Thus, the reliability of misfire can be improved.

  In the present embodiment, the gas fan heater is shown as the gas combustion apparatus of the present invention. However, when the misfire of the burner is detected, the solenoid valve provided in the gas supply pipe is closed to supply the fuel gas to the burner. The present invention can be applied to any gas combustion apparatus that stops the supply of gas.

  In the present embodiment, the transistor 31 is used as the switching means of the present invention, but an FET or a relay may be used.

  DESCRIPTION OF SYMBOLS 1 ... Burner, 2 ... Gas supply pipe, 3 ... 1st solenoid valve, 4 ... 2nd solenoid valve, 5 ... Proportional valve, 6 ... Thermocouple, 10 ... Controller, 12 ... 1st relay, 13 ... 2nd relay, DESCRIPTION OF SYMBOLS 20 ... Microcomputer, 31 ... Transistor, 30 ... Switching state detection circuit, 32 ... Transistor drive circuit, 33 ... Monitoring circuit, 35 ... Relay answer-on circuit

Claims (1)

With a burner,
A gas supply pipe for supplying fuel gas to the burner;
An electromagnetic valve for opening and closing the gas supply pipe;
Switching means connected between a power source and a drive coil of the solenoid valve;
A thermocouple for detecting the combustion state of the burner;
Combustion control means for performing control to turn off the switching means when detecting burnout of the burner from the detection signal of the thermocouple while performing ignition processing of the burner;
A gas having a monitoring circuit that starts after the burner ignition process and performs control to turn off the switching means when the level of the detection signal of the thermocouple falls below a first misfire determination value; In the combustion device,
Switching state detection means for detecting whether the switching means is on or off; and
Monitoring circuit forced activation means for performing control to activate the monitoring circuit regardless of the presence or absence of ignition processing of the burner;
Forced off control means for performing control to turn off the switching means regardless of the operation of the monitoring circuit;
When the burner is in a fire extinguishing state, it is determined whether the level of the detection signal of the thermocouple is equal to or lower than a second misfire determination value set to be equal to or lower than the first misfire determination value. When the level of the detection signal is less than or equal to the second misfire determination value, the monitoring circuit is forcibly activated by the monitoring circuit forcibly starting the control circuit, and the switching state detecting means is for turning off the switching means. A first misfire correspondence confirmation process is performed to determine whether or not it is detected, and when the level of the detection signal of the thermocouple exceeds the second misfire determination value, the forcing-off means causes the switching means to A second misfire countermeasure confirmation process is executed to determine whether or not the switching state detecting means detects that the switching means is in the off state by performing control to turn off. In the first misfire correspondence confirmation process or the second misfire correspondence confirmation process, provided with a misfire correspondence confirmation means for prohibiting the burner ignition process when the switching means is not detected to be in an OFF state. A gas combustion apparatus characterized by that.

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