JP2017096594A - Burning appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a short-circuit trouble diagnosis of a capacitor constituting a differential circuit to be carried out in a short time at a burning appliance that is constituted to charge a smoothing capacitor by a watch dog pulse through a differential circuit, and a switching circuit for conducting a solenoid valve to a power supply by a control voltage held by the smoothing capacitor is ON operated to close automatically the solenoid valve at the time of runaway of a micro-computer.SOLUTION: There is provided a discharge circuit 7 for forcedly grounding a smooth capacitor C1, the smooth capacitor C1 is grounded through the discharge circuit 7 to cause a capacitor C2 of a differential circuit 4 to be fully charged while the smooth capacitor C1 is being prevented from being charged, thereafter, a short-circuit trouble diagnosis of the capacitor C2 in the differential circuit 4 is carried out in reference to a response at the time of finishing of the ground control of the smoothing capacitor C1 by the discharge circuit 7.SELECTED DRAWING: Figure 1

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 solenoid valve, or a gas instantaneous water heater, and more particularly to a battery type combustion device that can be suitably used as a battery power source.

  Conventionally, as disclosed in, for example, Patent Document 1 below, in a combustion apparatus such as a battery-powered gas stove, a pulse from a microcomputer is automatically set so that an electromagnetic valve automatically closes when a microcomputer that performs operation control runs away. A waveform watchdog signal is output to the solenoid valve drive circuit. The drive circuit outputs the watchdog signal to the control terminal (base in the case of a bipolar transistor) of the semiconductor switching element via the RC series differentiating circuit, so that only when the watchdog signal is normally output, The valve is connected to the power supply battery, and the electromagnetic valve is cut off from the power supply when the watchdog signal is fixed to High or Low by the runaway of the microcomputer.

JP-A-8-270822

  In the above conventional technique, the short-circuit failure of the coupling capacitor (19) constituting the differentiation circuit is not taken into consideration. If the microcomputer runs out of control when the capacitor is short-circuited, the solenoid valve is electrically connected to the power supply and opened. There is a possibility that control will become impossible in the valved state.

  FIG. 3 shows a schematic configuration of a drive circuit of the solenoid valve L in the combustion equipment capable of performing a short circuit fault diagnosis of the capacitor constituting the differentiation circuit. The combustion device includes an electromagnetic valve L that opens and closes a fuel supply path to a combustion unit such as a gas burner, a microcomputer 1 that controls the opening and closing operation of the electromagnetic valve L, and a control command from the microcomputer 1 And a drive circuit 2 that outputs a drive voltage to the solenoid valve L.

  The microcomputer 1 includes a watchdog signal output terminal (first output terminal) capable of controlling the output of a watchdog signal having a pulse waveform, a solenoid valve on output terminal capable of controlling the output of a solenoid valve on command, and a solenoid valve L. An electromagnetic valve check input terminal for confirming whether or not a drive voltage is being output is provided.

  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 the power source V 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 electrically connected to the power source V only when both the switching circuits S1 and S2 are turned on. When a drive voltage based on the voltage is supplied to the solenoid valve L and any one of the switching circuits S1 and S2 is turned off, the solenoid valve L is disconnected from the power source V so that the drive voltage is not output to the solenoid valve L. It is configured.

  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 that is not a pulse signal is output from the watchdog signal output terminal, the current supply from the watchdog signal output terminal to the smoothing capacitor C1 is interrupted by the coupling capacitor C2 constituting the differentiating circuit 4, 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 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. At the time of open output, the switching element Q3 is turned off, and when the solenoid valve L is opened, a Low signal is output as a solenoid valve ON command signal. As a result, the switching element Q3 is turned on.

  When all of the switching elements Q1, Q2, and Q3 are turned on, the electromagnetic valve L is conducted to the power source V through the switching elements Q1 and Q3, and the drive voltage of the electromagnetic valve L is output from the collector output of the switching element Q3. . In order to cut back electromotive force due to switching of the switching element Q3, a negative voltage cutting diode D3 is connected to the collector output of the switching element Q3.

  Further, in order to confirm whether or not the switching elements Q1, Q2 and Q3 are operating normally, the collector output of the switching element Q3 (that is, the solenoid valve driving voltage output portion of the driving circuit 2) is monitored with a driving voltage monitor. A circuit 5 is provided. The monitoring circuit 5 in the illustrated example is mainly constituted 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 collector output of the switching element Q3 via a base resistor R6. The base and emitter of the 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 drive voltage output to the solenoid valve L is a voltage sufficient to open the solenoid valve L (or to keep it open when the solenoid valve L is a holding valve or the like), the switching voltage is generated by the drive voltage. Q4 is turned on 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 drive voltage is insufficient, the switching element Q4 is turned off, the connection point 6 is pulled up, and a 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. If a high signal is being 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.

  Further, the microcomputer 1 is configured to perform a short circuit fault diagnosis of the coupling capacitor C2 constituting the differentiation circuit 4 at the time of power-off processing. The short-circuit fault diagnosis will be described below. If the output of the watchdog signal output terminal continues to be in the Low state for several seconds before the power-off process, the smoothing capacitor C1 and the coupling capacitor C2 are connected as shown in FIG. Due to the natural discharge, almost no charge is charged.

  In this state, when the power is turned off by the user or when the power-off process is started by the self-power-off control by leaving for a predetermined time, the microcomputer 1 outputs a High signal, that is, a DC signal from the watchdog signal output terminal. .

  Then, the coupling capacitor C2 and the smoothing capacitor C1 of the differentiating circuit 4 are fully charged in about several tens of milliseconds, whereby both the switching elements Q2 and Q1 are turned on and the switching element Q3 is also controlled to be turned on. As a result, the input signal of the solenoid valve check input terminal becomes a Low signal. At this time, the electromagnetic valve L opens, but gas leakage does not occur by closing other electromagnetic valves or manual valves connected in series with the electromagnetic valve L.

  If the High signal is continuously output from the watchdog signal output terminal as it is, if the short-circuit failure does not occur in the coupling capacitor C2, the coupling capacitor C2 is fully charged, so that the coupling capacitor C2 is switched to the smoothing capacitor C1. The charge charged in the smoothing capacitor C1 is gradually discharged through the resistance component of the switching element Q2, and the voltage across the smoothing capacitor C1 needs to drive the switching element Q2 after a few seconds. When the switching element Q2 is turned off and the switching element Q1 is turned off, the input signal of the solenoid valve check input terminal becomes a high signal. By detecting this High signal input, it is diagnosed that there is no short-circuit failure of the coupling capacitor C2, the short-circuit failure diagnosis ends normally, and then the power is turned off.

  On the other hand, if the coupling capacitor C2 is short-circuited, as shown by the dotted line in FIG. 4, the charge is supplied from the watchdog signal output terminal to the smoothing capacitor C1, and even with time, The voltage across the smoothing capacitor C1 does not drop, and therefore the switching elements Q1 and Q2 do not turn off indefinitely. In this case, if it is normal and the switching element Q1 and Q2 do not turn off even after the specified time until the turning-off operation has elapsed, it is determined that a short-circuit fault has occurred in the coupling capacitor C2, and a predetermined error has occurred. In addition to performing notification, it is possible to perform a predetermined process such as storing a significant error occurrence in a nonvolatile memory.

  According to the above configuration, the short-circuit fault diagnosis of the coupling capacitor C2 can be performed. However, it is necessary to wait for the discharge of the smoothing capacitor C1 until it is determined that there is a short-circuit fault. For example, it takes about 3 to 5 seconds. In a combustion device such as a battery-type gas stove that employs a battery as a power source, if the short-circuit fault diagnosis is performed for several seconds every time the power-off process is performed, the power cannot be turned off until the diagnosis is completed. In such a case, standby power is consumed and the short-circuit fault diagnosis process itself consumes power, which affects the battery life.

  Therefore, the present invention charges a smoothing capacitor by a watchdog pulse through a differentiating circuit, and turns on a switching circuit that causes a solenoid valve to be connected to a power source by a control voltage held by the smoothing capacitor. An object of the present invention is to provide a combustion device that can perform a short-circuit fault diagnosis process of a coupling capacitor of the differential circuit in a short time in a combustion device that is configured to automatically close an electromagnetic valve.

  The present invention relates to an electromagnetic valve that opens and closes a fuel supply path, a switching circuit that can be turned on to connect the solenoid valve to a power source, and that shuts off the solenoid valve from the power source during an off operation, and a control terminal of the switching circuit And a smoothing capacitor capable of holding a control voltage for turning on the switching circuit, and a control having a first and a second output terminal and capable of controlling the output of a pulse signal from the first output terminal And a differentiating circuit provided between the first output terminal and the smoothing capacitor, the differentiating circuit having a coupling capacitor connected in series to the smoothing capacitor, When a pulse signal is output from the output terminal 1, current is supplied in a pulsed manner to the smoothing capacitor via the differentiation circuit. When the smoothing capacitor is charged and no pulse signal is output from the first output terminal, the coupling capacitor of the differentiation circuit cuts off the current supply from the first output terminal to the smoothing capacitor. In the combustion equipment, the following technical measures were taken to achieve the above object.

  That is, the combustion device of the present invention further includes a discharge circuit that grounds the smoothing capacitor when a forced-off command is output from the second output terminal of the control unit, and the control unit includes the coupling capacitor. The short-circuit fault diagnosis process is configured to be executable, and the short-circuit fault diagnosis process outputs a DC signal from the first output terminal and outputs a forced OFF command from the second output terminal, and then the first short-circuit fault diagnosis process. The configuration is such that when the forced-off command output from the second output terminal is stopped while maintaining the DC signal output from the output terminal, the coupling capacitor is diagnosed as a short-circuit fault when the switching circuit is turned on. (Claim 1).

  According to the combustion apparatus of the present invention, when the smoothing capacitor is grounded by the discharge circuit, the electric charge charged in the smoothing capacitor is forcibly and rapidly discharged, and then the forced off command output is stopped. If there is a short circuit failure, the smoothing capacitor is immediately charged and the switching circuit is turned on, so that the short circuit failure can be detected in a very short time (for example, several tens of milliseconds to several hundreds of milliseconds). Therefore, the short circuit failure diagnosis time of the coupling capacitor of the differentiating circuit can be greatly shortened, and the battery life can be prolonged by reducing the power consumption.

  In the combustion apparatus of the present invention, the control unit is configured to perform its own power-off process when a predetermined power-off condition is satisfied, and the short-circuit failure diagnosis process is performed during the power-off process. (Claim 2). According to this, the time required for the power-off process can be significantly shortened, and the battery life can be extended. Note that the power-off condition may be appropriate, for example, that the user has performed a power-off operation, or that the non-operation time has been continued by a user for a predetermined period or longer.

  In the combustion apparatus of the present invention, the control unit may be configured to execute the short-circuit fault diagnosis process during a startup process when power is turned on. According to this, it is possible to perform failure diagnosis without making the user feel uncomfortable even when the combustion device is turned on by greatly shortening the short-circuit failure diagnosis time. The operational stability can be further improved.

It is a schematic circuit diagram of the solenoid valve drive circuit of the combustion apparatus which concerns on one Embodiment of this invention. It is a timing chart of the short circuit fault diagnosis of the coupling capacitor of the differentiation circuit in the combustion apparatus. It is a schematic circuit diagram of the solenoid valve drive circuit of the combustion apparatus of a development stage. It is a timing chart of the short circuit fault diagnosis of the coupling capacitor of the differentiation circuit in the combustion apparatus.

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

  FIG. 1 is a schematic circuit diagram of a solenoid valve drive circuit for a combustion device according to an embodiment of the present invention. The same reference numerals are given to the same components as those of the above-mentioned development device of the present application stage. Detailed description will be omitted, and different configurations and operations will be described.

  In the present embodiment, the microcomputer 1 (control unit) further includes a forced-off output terminal (second output terminal) composed of an open collector output terminal as the output terminal, and the forced-off output terminal is the first switching terminal. By connecting to the control terminal 3 of the circuit S1, the discharge circuit 7 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. Note that the discharge circuit can also be configured using a transistor provided outside the microcomputer 1.

  According to the combustion device of this embodiment having such a circuit configuration, a short-circuit fault diagnosis of the coupling capacitor C2 of the differentiation circuit 4 can be performed almost instantaneously in about several tens of milliseconds as described below.

  That is, the failure diagnosis process by the microcomputer 1 of the present embodiment is configured to be executed by the following sequence. First, as shown in FIG. 2, while outputting a High signal (DC signal) from the watchdog signal output terminal, the forced-off command output from the forced-off output terminal is turned on. The state of the forced-off signal in FIG. 2 is illustrated with the peak of the figure when the forced-off command is on (that is, when the Low signal is output) and the valley of the figure when the forced-off command is off (that is, when the output is open).

  At this time, the coupling capacitor C2 of the differentiating circuit 4 is fully charged in several milliseconds to several tens of milliseconds by the High signal output from the watchdog signal output terminal. On the other hand, the smoothing capacitor C1 is not charged because it is grounded by the discharge circuit 7.

  The time until the coupling capacitor C2 is fully charged is measured in advance by a test or the like, and a sufficient time for the coupling capacitor C2 to be fully charged (for example, about several tens of milliseconds), a forced OFF command output is output. After the continuation, the forced-off command output is stopped while the High signal is output from the watchdog signal output terminal.

  At this time, if the coupling capacitor C2 is not short-circuited, since the coupling capacitor C2 is already fully charged, no charge is transferred from the coupling capacitor C2 to the smoothing capacitor C1. The electric charge of the capacitor is maintained at almost 0, the switching elements Q1 and Q2 are not turned on, and the High signal is continuously input to the solenoid valve check input terminal.

  On the other hand, when the coupling capacitor C2 is short-circuited, the High signal output from the watchdog signal output terminal passes through the coupling capacitor C2 and is applied to the smoothing capacitor C1. The switching elements Q1 and Q2 are immediately turned on, and the Low signal is input to the solenoid valve check input terminal. The time from the high signal output from the watchdog output terminal until the Low signal appears as the input signal of the solenoid valve check input terminal as described above is only tens of milliseconds, and at most several hundred milliseconds. The short-circuit fault diagnosis of the coupling capacitor C2 can be completed instantaneously in a very short time.

  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.

  Further, the combustion device may be provided with a plurality of solenoid valves. In this case, the switching elements Q3 and the solenoid valve ON output terminals of the microcomputer 1 are provided for each solenoid valve, and the plurality of switching elements Q3 are provided. By connecting in parallel to the switching element Q1, it is possible to individually control the opening / closing operation for each electromagnetic valve while sharing the first switching circuit S1 that functions as a safety circuit based on a watchdog signal. 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.

  Further, the switching circuit S1 may be mainly constituted by one semiconductor switching element or may be constituted by three or more semiconductor switching elements.

  Although the differentiation circuit 4 is exemplified by the RC series circuit in the above embodiment, the differentiation circuit 4 may be configured by a differentiation circuit using an operational amplifier as long as it includes a coupling capacitor C2 connected in series with the smoothing capacitor C1. Good.

1 Control unit (microcomputer)
2 Drive circuit 3 Control terminal of switching circuit 4 Differentiation circuit 7 Discharge circuit L Solenoid valve V Power supply (battery)
S1 Switching circuit C1 Smoothing capacitor C2 Coupling capacitor

Claims (3)

An electromagnetic valve that opens and closes a fuel supply path, a switching circuit that can be turned on to connect the solenoid valve to a power supply, and that shuts off the solenoid valve from the power supply during an off operation, and a control terminal of the switching circuit And a smoothing capacitor capable of holding a control voltage for turning on the switching circuit, a control unit having first and second output terminals and capable of controlling output of a pulse signal from the first output terminal, A differential circuit provided between a first output terminal and the smoothing capacitor, the differential circuit having a coupling capacitor connected in series to the smoothing capacitor, the first output terminal When a pulse signal is output from the smoothing capacitor, the smoothing capacitor is supplied in pulses to the smoothing capacitor via the differentiating circuit. Combustion equipment in which a current is supplied from the first output terminal to the smoothing capacitor by the coupling capacitor of the differentiating circuit when a capacitor is charged and no pulse signal is output from the first output terminal. In
A discharge circuit for grounding the smoothing capacitor when a forced-off command is output from the second output terminal of the control unit; and the control unit is configured to execute a short-circuit fault diagnosis process for the coupling capacitor And
The short-circuit fault diagnosis process outputs a DC signal from the first output terminal and outputs a forced off command from the second output terminal, and then maintains a DC signal output from the first output terminal. A combustion apparatus configured to diagnose a short-circuit failure of the coupling capacitor when the switching circuit is turned on when the forced-off command output from the second output terminal is stopped.   2. The combustion device according to claim 1, wherein the control unit is configured to perform its own power-off process when a predetermined power-off condition is satisfied, and the short-circuit failure diagnosis process is executed during the power-off process. Combustion equipment characterized by being configured as described above.   3. The combustion apparatus according to claim 1, wherein the control unit is configured to execute the short-circuit fault diagnosis process during a startup process when power is turned on.

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