JP6604164B2 - Combustion equipment - Google Patents

Description

  The present invention relates to a combustion device such as a gas stove equipped with an electromagnetic valve such as an electromagnetic safety valve or an original gas electromagnetic valve, or a gas instantaneous water heater.

  Conventionally, in a combustion device such as a gas stove or gas instantaneous water heater, an electromagnetic valve such as an electromagnetic safety valve or an original gas solenoid valve provided in the middle of a fuel supply path for supplying fuel gas to a combustion part such as a gas burner is used. A drive circuit failure diagnosis function is provided.

  For example, in Patent Document 1 below, a semiconductor switch, a diode, and an electromagnetic valve are connected in series and connected to an operating power supply, and a capacitor is connected in parallel with the electromagnetic valve. The capacitor is charged more than the required drive voltage of the solenoid valve by turning it on and off intermittently to drive the solenoid valve, while the correspondence between the level change of the connection point between the semiconductor switch and the diode and the waveform of the pulse signal Discloses a technique for determining failure of the semiconductor switch during combustion.

JP-A-8-270822

  However, according to the configuration of the above prior art, the semiconductor switch is always switched on / off by the pulse signal while the solenoid valve is driven, and the power consumption for the on / off switching is relatively large. In particular, in battery-powered gas stoves, the battery life is affected. Furthermore, the drive voltage of the solenoid valve always becomes a pulsating waveform, which is not preferable for the stability of the solenoid valve operation. On the other hand, if the drive voltage is designed to have a small amplitude, it is difficult to determine a failure.

  Therefore, the present invention is capable of stably opening the solenoid valve with low power consumption when the failure diagnosis is not performed in the combustion device that performs failure diagnosis of the switching circuit for driving the solenoid valve during combustion. The purpose is to.

  In order to achieve the above object, the present invention takes the following technical means.

  That is, the present invention relates to an electromagnetic valve that opens and closes a fuel supply path, a control unit that outputs an electromagnetic valve on signal during open operation control of the electromagnetic valve, and the electromagnetic valve that is output when the electromagnetic valve on signal is output And a switching circuit (second switching circuit) that operates to shut off the solenoid valve from the power source when the solenoid valve ON signal is not output, the combustion valve is connected to the power source. A drive voltage holding circuit for holding at least temporarily a drive voltage applied to the electromagnetic valve when the state is changed from a conductive state to a state where the power supply is cut off; Failure diagnosis for performing failure diagnosis of the switching circuit based on the output state of the switching circuit when the solenoid valve ON signal is output in a pulse shape during open operation control And it has a capability, as it is not the fault diagnosis during opening operation control of the electromagnetic valve is characterized in that for outputting a constantly the solenoid valve ON signal (claim 1).

  According to the combustion apparatus of the present invention, the watchdog pulse input to the differentiation circuit is not used for failure diagnosis of the switching circuit for driving the solenoid valve, but the solenoid valve on signal is output in a pulse form at the time of failure diagnosis. Failure diagnosis can be performed depending on whether or not the output of the switching circuit is a pulse signal. Since the criteria for such failure diagnosis are clear, failure determination can be performed easily and accurately. On the other hand, since the drive voltage applied to the solenoid valve is held by the drive voltage holding circuit, the solenoid valve can be stably held in the open operation state even if the output of the switching circuit temporarily becomes a pulse signal. it can. In addition, when failure diagnosis is not performed, it is possible to avoid an unnecessary increase in the number of switching operations by constantly outputting the solenoid valve ON signal, thereby reducing power consumption and extending battery life. it can.

  The present invention also provides an electromagnetic valve that opens and closes a fuel supply path, a control unit that outputs an electromagnetic valve off signal during the closing operation control of the electromagnetic valve, and the electromagnetic valve when the electromagnetic valve off signal is not output. And a switching circuit (first switching circuit) that operates to shut off the solenoid valve from the power source when the solenoid valve off signal is output. A drive voltage holding circuit for holding at least temporarily a drive voltage applied to the electromagnetic valve when the state is changed from a conductive state to a state where the power supply is cut off; Failure diagnosis function for performing failure diagnosis of the switching circuit based on the output state of the switching circuit when the electromagnetic valve off signal is output in a pulse shape during open operation control And having, in the case of not performing the failure diagnosis during the opening operation control of the electromagnetic valve is characterized in that not output constantly the solenoid valve OFF signal (claim 2).

  According to the combustion apparatus of the present invention, the watchdog pulse input to the differentiation circuit is not used for failure diagnosis of the switching circuit for driving the solenoid valve, but the solenoid valve off signal is output in a pulse form at the time of failure diagnosis. Failure diagnosis can be performed depending on whether or not the output of the switching circuit is a pulse signal. Since the criteria for such failure diagnosis are clear, failure determination can be performed easily and accurately. On the other hand, since the drive voltage applied to the solenoid valve is held by the drive voltage holding circuit, the solenoid valve can be stably held in the open operation state even if the output of the switching circuit temporarily becomes a pulse signal. it can. In addition, when failure diagnosis is not performed, it is possible to avoid an unnecessary increase in the number of switching operations by constantly outputting the solenoid valve ON signal, thereby reducing power consumption and extending battery life. it can.

  Further, the present invention provides an electromagnetic valve that opens and closes a fuel supply path, first and second switching circuits provided in series between the electromagnetic valve and a power source, and during the closing operation control of the electromagnetic valve, A controller that outputs an electromagnetic valve off signal to the first switching circuit and outputs an electromagnetic valve on signal to the second switching circuit during the opening operation control of the electromagnetic valve; The switching circuit operates to connect the solenoid valve to a power source when the solenoid valve off signal is not output and to shut off the solenoid valve from the power source when the solenoid valve off signal is output. The switching circuit connects the solenoid valve to a power source when the solenoid valve on signal is output, and shuts off the solenoid valve from the power source when the solenoid valve on signal is not output. In a combustion apparatus that operates, a driving voltage holding circuit that holds at least temporarily a driving voltage applied to the solenoid valve when the solenoid valve transitions from a state in which the solenoid valve is connected to a power source to a state in which the solenoid valve is disconnected from the power source The control unit further includes the first and second outputs when the electromagnetic valve on signal is constantly output and the electromagnetic valve off signal is output in a pulsed manner during the opening operation control of the electromagnetic valve. A first failure diagnosis function for diagnosing the failure of the first switching circuit based on an output state of the switching circuit; and outputting the solenoid valve on signal in a pulsed manner during the opening operation control of the solenoid valve; A second failure diagnosis function for performing failure diagnosis of the second switching circuit based on output states of the first and second switching circuits when the valve-off signal is not constantly output. In addition, when neither failure diagnosis by the first and second failure diagnosis functions is performed, the solenoid valve OFF signal is not constantly output during the opening operation control of the solenoid valve, and The electromagnetic valve ON signal is output (claim 3).

  According to the combustion apparatus of the present invention, the watchdog pulse input to the differentiation circuit is not used for failure diagnosis of the switching circuit for driving the solenoid valve, but one of the solenoid valve on signal and the solenoid valve off signal fails. It is possible to perform failure diagnosis of the first or second switching circuit depending on whether or not the output of the first and second switching circuits becomes a pulse signal by outputting in a pulse form at the time of diagnosis. Since the criteria are clear, the failure determination can be performed easily and accurately. On the other hand, since the drive voltage applied to the solenoid valve is held by the drive voltage holding circuit, the solenoid valve can be stably held in the open operation state even if the output of the switching circuit temporarily becomes a pulse signal. it can. In addition, when failure diagnosis is not performed, it is possible to avoid an unnecessary increase in the number of switching operations by constantly outputting the solenoid valve ON signal, thereby reducing power consumption and extending battery life. it can.

  In the combustion apparatus of the present invention, the control unit is configured to monitor the drive voltage applied to the electromagnetic valve and not perform the failure diagnosis when the voltage falls below a predetermined threshold. (Claim 4). According to this, when the solenoid valve drive voltage does not rise sufficiently for some reason, such as when the battery voltage drops when a battery is used as the power source, the solenoid valve is unintentionally closed by performing the above fault diagnosis. It is possible to avoid operating.

  In addition, the control unit may be configured not to perform the next failure diagnosis until a predetermined time has elapsed after performing the failure diagnosis. According to this, even if the drive voltage held by the drive voltage holding circuit is reduced by the pulse drive of the switching circuit under failure diagnosis, the voltage held by the drive voltage holding circuit can be restored after a predetermined time. In the case of having the first and second failure diagnosis functions, the failure diagnosis by any failure diagnosis function is not performed until a predetermined time has elapsed after the failure diagnosis by any failure diagnosis function is performed. To.

  In the combustion apparatus of the present invention, the failure diagnosis may be performed in a timely manner, and may be performed periodically every predetermined time during the solenoid valve opening operation control, or when a predetermined condition is satisfied. It may be performed. Moreover, it is preferable that the failure diagnosis by the first and second failure diagnosis functions is performed alternately, but an appropriate number of times such as relatively increasing the number of failure diagnosis by any of the first and second failure diagnosis functions is suitable. Can be.

  In addition, it is preferable to configure the circuit so that the output waveform of the switching circuit becomes a pulse waveform when the solenoid valve on signal or the solenoid valve off signal is output in a pulse shape at the time of failure diagnosis. Fault diagnosis based on the output state can be performed easily and accurately. In addition, by using an integration circuit as the drive voltage holding circuit, the voltage applied to the electromagnetic valve can be stabilized even if the output waveform of the switching circuit is a pulse waveform.

  In addition, the first switching circuit that is turned off by the solenoid valve off signal is turned on by the watchdog pulse output by the control unit. However, even if the watchdog pulse is output by the output of the solenoid valve off signal, Can be configured to operate off.

It is a schematic circuit diagram of the drive circuit of the solenoid valve in the combustion equipment which concerns on one Embodiment of this invention. It is a timing chart during electromagnetic valve opening operation control of the combustion equipment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of a drive circuit of an electromagnetic valve L in a combustion device according to an embodiment of the present invention. The combustion device opens and closes a fuel supply path to a combustion section such as a gas burner. And a microcomputer 1 as a control unit for controlling the opening / closing operation of the solenoid valve L, and a drive circuit 2 for outputting a drive voltage to the solenoid valve L in response to a control command from the microcomputer 1.

  The microcomputer 1 includes a watchdog signal output terminal capable of controlling the output of a watchdog signal having a pulse waveform, a forced off output terminal capable of controlling the output of a forced off command (solenoid valve off signal), and a solenoid valve on command (solenoid valve). Solenoid valve ON output terminal capable of controlling the output of the ON signal), a solenoid valve check input terminal for confirming whether or not a drive voltage is output to the solenoid valve L, and the solenoid valve L. And a solenoid valve drive voltage monitoring input terminal for confirming the voltage.

  The drive circuit 2 includes first and second switching circuits S1 and S2 that can be turned on to electrically connect the solenoid valve L to a power source V (for example, a battery) and that shut off the solenoid valve L from the power source during the off operation. The first and second switching circuits S1 and S2 are connected in series between the power source V and the solenoid valve L, and the solenoid valve L is set to the power source V only when both the switching circuits S1 and S2 are turned on. The drive voltage based on the power supply voltage is supplied to the solenoid valve L. When any one of the switching circuits S1 and S2 is turned off, the solenoid valve L is disconnected from the power supply V and the drive voltage is applied to the solenoid valve L. It is configured not to output.

  The first switching circuit S1 is mainly composed of two semiconductor switching elements Q1 and Q2. One switching element Q1 is a pnp transistor provided in the middle of a power supply path from the power supply V to the solenoid valve L. It is configured. The switching element Q1 has an emitter connected to the power supply V side and a collector connected to the solenoid valve L side. The emitter and base of the switching element Q1 are connected via a resistor R1.

  Another switching element Q2 is configured by an npn transistor whose collector is connected to the base of the switching element Q1 via a base resistor R2. The emitter (ground terminal) of the switching element Q2 is grounded, and the base of the switching element Q2 becomes the control terminal 3 of the first switching circuit S1.

  A smoothing capacitor C1 capable of holding a control voltage for turning on the switching element Q2 is connected to the control terminal 3 via a base resistor R3. The negative terminal of the smoothing capacitor C1 is grounded. ing. The smoothing capacitor C1 and the watchdog signal output terminal of the microcomputer 1 are connected via the RC series differentiating circuit 4, so that when a watchdog signal having a pulse waveform is output from the watchdog signal output terminal. By supplying a current to the smoothing capacitor C1 in a pulsed manner through the differentiating circuit 4, the smoothing capacitor C1 is charged to the control voltage or higher, and the switching elements Q2 and Q1 are sequentially turned on. On the other hand, when a DC signal (High signal or Low signal) that is not a pulse signal is output from the watchdog signal output terminal, the coupling capacitor C2 constituting the differentiating circuit 4 causes the watchdog signal output terminal to pass to the smoothing capacitor C1. Current supply is cut off, and the switching elements Q2 and Q1 are sequentially turned off by the discharge of the smoothing capacitor C1.

  A diode D1 for cutting negative voltage is provided between the output part of the differentiating circuit 4 and the ground, and a backflow prevention diode D2 is provided between the output part of the differentiating circuit 4 and the smoothing capacitor C1.

  Further, the control terminal 3 is connected to a forced-off output terminal of the microcomputer 1. This forced-off output terminal is constituted by an open collector output terminal, and a discharge circuit is configured to ground the positive terminal of the smoothing capacitor C1 when a Low signal is output as a forced-off command from the forced-off output terminal. Thereby, in the case of emergency closing control of the solenoid valve L, the smoothing capacitor C1 is rapidly discharged by the microcomputer 1 outputting a forced-off command, and the switching circuit 1 can be turned off instantaneously. Yes. On the other hand, when the solenoid valve L is opened, the switching circuit 1 can be turned on by the watchdog signal by setting the forced-off output terminal as an open output and not outputting the forced-off command. Yes. The discharge circuit is configured by using a transistor provided outside the microcomputer 1, and the microcomputer 1 outputs a forced OFF command (electromagnetic valve OFF signal) of a High signal or Low signal to the discharge circuit. Is also possible.

  Further, the smoothing capacitor C1 and the coupling capacitor C2 of the differentiating circuit 4 have the same capacity, and direct current is supplied from the watchdog signal output terminal to the differentiating circuit 4 in a state where no charge is accumulated in these capacitors C1 and C2. When a signal is output, both capacitors C1 and C2 are charged to substantially the same potential due to the movement of charge between these capacitors C1 and C2. At this time, the smoothing capacitor C1 turns on the switching element Q2. It is temporarily charged to a voltage sufficient for operation. While the output of the DC signal is continued, the coupling capacitor C2 of the differentiating circuit 4 is maintained in a fully charged state, but after the coupling capacitor C2 is fully charged, the charge between the capacitors C1 and C2 is maintained. Therefore, the charge accumulated in the smoothing capacitor C1 is gradually discharged mainly through the base-emitter resistance component of the switching element Q2, and the voltage across the smoothing capacitor C1 is changed to the switching element Q2 in about several seconds. Descent to the extent that it is turned off.

  The second switching circuit S2 is mainly composed of one semiconductor switching element Q3. The switching element Q3 is composed of a pnp transistor, and is connected in series with the switching element Q1 between the power source V and the electromagnetic valve L. That is, the emitter of the switching element Q3 is connected to the collector of the switching element Q1, and the collector of the switching element Q3 is connected to the solenoid valve L side. The emitter and base of the switching element Q3 are connected via a resistor R4, and the base of the switching element Q3 is connected to an electromagnetic valve ON output terminal of the microcomputer 1 via a base resistor R5. In the illustrated example, the solenoid valve ON output terminal is constituted by an open collector output terminal. When the solenoid valve L is open (when the solenoid valve ON signal is not output), the switching element Q3 is turned OFF and the solenoid valve L is opened. The switching element Q3 is turned on by outputting a Low signal as an ON signal.

  When all of the switching elements Q1, Q2, and Q3 are turned on, the solenoid valve L is conducted to the power source V through the switching elements Q1 and Q3, and the power source voltage is supplied as the drive voltage of the solenoid valve L from the collector output of the switching element Q3. Is output. Thus, the collector output of the switching element Q3 becomes the output of the drive circuit 2 of the present embodiment. Note that a negative voltage cutting diode D3 is connected to the collector output of the switching element Q3 in order to cut back electromotive force due to switching of the switching element Q3.

  Further, in order to confirm whether or not the switching elements Q1, Q2, and Q3 are operating normally, an output voltage confirmation circuit 5 is provided at the output portion of the drive circuit 2. The confirmation circuit 5 in the illustrated example is mainly configured by a semiconductor switching element Q4 composed of a pnp transistor whose emitter is grounded, and the base of the switching element Q4 is connected to the output portion of the drive circuit 2 (the switching element Q3 of the switching element Q3) via a base resistor R6. The base and emitter of the switching element Q4 are connected via a resistor R7. The collector of the switching element Q4 is connected to the power source V via the load resistor R8, and the connection point 6 between the load resistor R8 and the switching element Q4 is connected to the solenoid valve check input terminal of the microcomputer 1. When the voltage output from the drive circuit 2 toward the solenoid valve L is a voltage sufficient to open the solenoid valve L (when the solenoid valve L is a holding valve or the like, the voltage is held in the open state) The switching element Q4 is turned on by the output voltage to ground the connection point 6, and a Low signal is input to the solenoid valve check input terminal. On the other hand, when the output voltage is insufficient, the switching element Q4 is turned off, the connection point 6 is pulled up, and the High signal is input to the solenoid valve check input terminal. The microcomputer 1 outputs a pulse signal as a watchdog signal from the watchdog signal output terminal to open the solenoid valve L and outputs a Low signal as a solenoid valve on command signal from the solenoid valve on output terminal. However, when a high signal is input from the solenoid valve check input terminal, it is determined that some failure or malfunction has occurred, and the output of the watchdog signal and the solenoid valve on command signal is stopped, It is configured to perform error handling.

  The drive voltage output to the solenoid valve L is monitored by inputting the collector output of the switching element Q3 directly or by inputting the voltage divided by the voltage dividing circuit to the A / D input port of the microcomputer 1. You can also.

  In the present embodiment, a drive voltage holding circuit 8 is provided between the drive circuit 2 and the solenoid valve L. The drive voltage holding circuit 8 is configured so that the first and second switching circuits S1 are in a state where the solenoid valve L is electrically connected to the power source V when both the first and second switching circuits S1 and S2 are turned on. , S2 holds the drive voltage applied to the solenoid valve L at least temporarily when the power supply V is turned off by turning off, and in this embodiment, RC integration is performed. The positive electrode side terminal of the capacitor | condenser which comprises an integration circuit is connected to the solenoid valve L, and the negative electrode side terminal is earth | grounded. The capacitance of the capacitor constituting this integrating circuit can be designed as appropriate, but it is preferable that the solenoid valve L be closed by discharging in about several tens of milliseconds after being disconnected from the power supply V.

  The positive terminal of the capacitor of the drive voltage holding circuit 8 is connected to the solenoid valve drive voltage monitoring input terminal of the microcomputer 1. The monitoring input terminal can be constituted by an A / D input terminal, and the driving voltage applied to the electromagnetic valve L by the microcomputer 1 can be monitored in real time. The solenoid valve drive voltage can be monitored based on whether or not the drive voltage is less than a predetermined threshold by a circuit similar to the output voltage confirmation circuit 5 described above.

  In this embodiment, as shown in FIG. 2, the microcomputer 1 outputs a watchdog pulse (WD pulse) from the watchdog signal output terminal during the opening operation control of the solenoid valve L for combustion control, and forcibly turns off. The output is set to open output (a state in which the solenoid valve off signal is not output), and the solenoid valve on signal is output from the solenoid valve on output terminal to the second switching circuit S1. As a result, both the first and second switching circuits S1 and S2 of the drive circuit 2 are turned on, the solenoid valve L is conducted to the power source V, the output voltage from the drive circuit 2 rises instantaneously, and the drive The capacitor of the voltage holding circuit 8 is charged to the minimum drive voltage or more of the solenoid valve L in about several milliseconds to several tens of milliseconds, and the solenoid valve L opens.

  Further, the microcomputer 1 of the present embodiment includes a first failure diagnosis function for performing failure diagnosis of the first switching circuit S1 during the opening operation control of the solenoid valve L, and a second during control of the opening operation of the solenoid valve L. And a second failure diagnosis function for performing failure diagnosis of the switching circuit S2.

  As shown in FIG. 2, the first failure diagnosis function outputs a forced OFF command (electromagnetic) to the first switching circuit S1 while constantly outputting an electromagnetic valve ON signal to the second switching circuit S2. A failure diagnosis of the first switching circuit S1 is performed based on the state of the output of the drive circuit 2 (the output of the first and second switching circuits) when the valve-off signal) is output in the form of pulses, In the present embodiment, the failure determination is performed based on whether or not the input signal of the solenoid valve check input terminal is a pulse signal corresponding to the pulse output of the forced OFF command. Thus, the minimum voltage value of the pulse waveform appearing in the output signal of the drive circuit 2 is the output of the on / off operation of the switching element Q4 of the output voltage confirmation circuit 5 so that failure determination can be performed using the solenoid valve check input terminal. The circuit constant is designed to be smaller than the voltage check threshold.

  Further, the second failure diagnosis function causes the second switching circuit S2 to output the electromagnetic valve on signal in a pulsed manner, and does not constantly output the electromagnetic valve off signal to the first switching circuit S1. The failure diagnosis of the second switching circuit S2 is performed based on the output state of the driving circuit 2 at that time. The failure determination in the second failure diagnosis function is also determined depending on whether the input signal of the solenoid valve check input terminal is a pulse signal corresponding to the pulse output of the forced OFF command, as in the first failure diagnosis function. The determination is made.

  Failure diagnosis by the first and second failure diagnosis functions cannot be performed at the same time, and is preferably performed sequentially with a predetermined interval period. Although this interval period can be designed as appropriate, the next failure diagnosis is performed until a predetermined time required for the drive voltage held by the drive voltage holding circuit 8 to sufficiently rise, for example, a predetermined time of about several tens of milliseconds, elapses. Do not.

  Further, when the drive voltage input from the solenoid valve drive voltage monitoring input terminal becomes less than the drive voltage monitoring threshold necessary for holding the solenoid valve L in the open operation state, the microcomputer 1 performs the first and second operations. The control is configured not to perform any failure diagnosis by the failure diagnosis function, and the failure diagnosis is performed after the drive voltage returns to the above threshold value or more.

  The microcomputer 1 can be configured to immediately stop the combustion operation when detecting a short-circuit failure of at least one of the first and second switching circuits S1 and S2 by the failure diagnosis. In addition, after the combustion end operation by the user, it is also possible to perform an error notification or the like after quickly stopping the combustion operation by an appropriate end process according to the failure.

  The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate. For example, the microcomputer 1 can be configured by a microprocessor in which all functions are mounted on a single chip, or can be configured by mounting a plurality of parts such as a CPU, a memory, and an I / O processing unit on a substrate. You can also.

  The combustion device may include a plurality of solenoid valves. In this case, the second switching circuit S2 and the solenoid valve ON output terminal of the microcomputer 1 are provided for each solenoid valve, and a plurality of first solenoid valves are provided. By connecting the two switching circuits S2 in parallel to the output side of the first switching circuit S1, the first switching circuit S1 functioning as a safety circuit based on the watchdog signal is shared, and individually for each solenoid valve. Opening / closing operation control can be performed. The plurality of solenoid valves may be, for example, a plurality of solenoid safety valves provided for each of the plurality of combustion sections, or may be different types of solenoid valves such as a solenoid safety valve and a source gas solenoid valve, Further, an adsorption valve and a holding valve built in one original gas solenoid valve may be used.

  In addition, the drive voltage holding circuit can be configured to hold the drive voltage by supplying a voltage from the holding power source using, for example, a button battery as a holding power source. In this case, switching control can be performed by the microcomputer 1 by appropriately providing a switching circuit so that power supply from the holding power supply is not performed when the electromagnetic valve L is closed.

1 Control unit (microcomputer)
2 Drive circuit 8 Drive voltage holding circuit L Solenoid valve V Power supply (battery)
S1 first switching circuit S2 second switching circuit

Claims (5)

An electromagnetic valve that opens and closes the fuel supply path, a control unit that outputs an electromagnetic valve ON signal during the opening operation control of the electromagnetic valve, and the electromagnetic valve is electrically connected to a power source when the electromagnetic valve ON signal is output. In a combustion device comprising a switching circuit that operates to shut off the solenoid valve from a power source when the solenoid valve on signal is not output,
A drive voltage holding circuit for holding the drive voltage applied to the solenoid valve at least temporarily when the solenoid valve is transitioned from a state in which the solenoid valve is electrically connected to a state in which the solenoid valve is shut off from the power source;
The control unit has a failure diagnosis function for performing a failure diagnosis of the switching circuit based on an output state of the switching circuit when the solenoid valve ON signal is output in a pulse shape during the opening operation control of the solenoid valve. In addition, when the failure diagnosis is not performed, the combustion valve outputs the solenoid valve on signal steadily during the opening operation control of the solenoid valve. An electromagnetic valve that opens and closes the fuel supply path, a control unit that outputs an electromagnetic valve off signal during the closing operation control of the electromagnetic valve, and makes the electromagnetic valve conductive to a power source when the electromagnetic valve off signal is not output In a combustion device comprising a switching circuit that operates to shut off the solenoid valve from a power source when the solenoid valve off signal is output,
A drive voltage holding circuit for holding the drive voltage applied to the solenoid valve at least temporarily when the solenoid valve is transitioned from a state in which the solenoid valve is electrically connected to a state in which the solenoid valve is shut off from the power source;
The control unit has a failure diagnosis function for performing failure diagnosis of the switching circuit based on an output state of the switching circuit when the solenoid valve OFF signal is output in a pulse shape during the opening operation control of the solenoid valve. In addition, when the failure diagnosis is not performed, the solenoid valve OFF signal is not constantly output during the opening operation control of the solenoid valve. An electromagnetic valve for opening and closing the fuel supply path; first and second switching circuits provided in series between the electromagnetic valve and the power supply; and the first switching circuit during the closing operation control of the electromagnetic valve. And a controller that outputs an electromagnetic valve off signal to the second switching circuit during the opening operation control of the electromagnetic valve, and the first switching circuit includes the electromagnetic valve When the valve-off signal is not output, the solenoid valve is connected to a power source, and when the solenoid valve-off signal is output, the solenoid valve is operated to be disconnected from the power source. A combustor that operates to connect the solenoid valve to a power source when the solenoid valve on signal is output and to shut off the solenoid valve from the power source when the solenoid valve on signal is not output In,
A drive voltage holding circuit for holding the drive voltage applied to the solenoid valve at least temporarily when the solenoid valve is transitioned from a state in which the solenoid valve is electrically connected to a state in which the solenoid valve is shut off from the power source;
The control unit outputs the solenoid valve on signal steadily during the opening operation control of the solenoid valve and outputs the solenoid valve off signal in a pulse shape. A first failure diagnosis function for diagnosing a failure of the first switching circuit based on an output state; and outputting the solenoid valve on signal in a pulsed manner during the opening operation control of the solenoid valve; and the solenoid valve off signal And a second failure diagnosis function for diagnosing the failure of the second switching circuit based on the output state of the first and second switching circuits when the first and second switching circuits are not constantly output. When neither failure diagnosis by the failure diagnosis function 2 is performed, the solenoid valve off signal is not constantly output and the solenoid valve on signal is constantly output during the opening operation control of the solenoid valve. thing Combustion equipment and features.   4. The combustion apparatus according to claim 1, wherein the control unit monitors a drive voltage applied to the electromagnetic valve and performs the failure diagnosis when the voltage falls below a predetermined threshold value. Combustion equipment characterized in that it is configured so that there is no.   5. The combustion apparatus according to claim 1, wherein the control unit is configured not to perform a next failure diagnosis until a predetermined time has elapsed after performing the failure diagnosis. And combustion equipment.

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