JP4977122B2 - Gas detection device and combustion device for combustion device - Google Patents

Description

The present invention provides an incomplete combustion gas in a low-temperature operating state in which the electrical characteristics change in response to a combustible gas in a high-temperature operating state that is higher than the high-temperature-side sensitive temperature, and the temperature is lower than the high-temperature-side sensitive temperature A gas detector whose electrical characteristics change in response to
Heating means for heating the gas detector;
The operation of the heating means is controlled so as to alternately and repeatedly switch the gas detector between the high temperature operation state and the low temperature operation state, and combustible in the high temperature operation state based on the electrical characteristics of the gas detector. Gas detection device for combustion apparatus provided with control means for detecting normal gas and executing normal detection mode for detecting incomplete combustion gas in the low-temperature operating state, and combustion apparatus provided with the gas detection device About.

Such a gas detection device for a combustion device (hereinafter sometimes simply referred to as a gas detection device) repeatedly switches the gas detector alternately between a high temperature operation state and a low temperature operation state, and generates a combustible gas in the high temperature operation state. The normal detection mode for detecting and detecting the incomplete combustion gas in the low temperature operating state is executed.
Then, in the normal detection mode, based on the detection information of the combustible gas in the high temperature operating state, the fuel leakage from the combustion unit that burns the supplied fuel is detected, and the incomplete combustion gas in the low temperature operating state is detected. Based on this detection information, incomplete combustion in the combustion section is detected (for example, see Patent Document 1).
By the way, when the fuel supplied to the combustion section is gas fuel, the gas fuel is detected as flammable gas, and when the fuel is liquid fuel, the gas vaporized from the liquid fuel is detected as flammable gas. become.

  Although not clearly described in the above-mentioned Patent Document 1, the conventional gas detection device is configured such that the normal detection mode is executed as soon as the ignition process for igniting the combustion unit is started. It had been.

JP 2000-193623 A

By the way, during the ignition process for igniting the combustion part, and after the ignition process until the combustion of the combustion part becomes stable, an ignition mistake or extinction is likely to occur. The predetermined period (hereinafter, sometimes referred to as an initial combustion start period) is more likely to cause fuel leakage than incomplete combustion.
However, in the conventional gas detection device, the normal detection mode is executed as soon as the ignition process is started, and the gas detection in the normal detection mode is executed even during the initial combustion start period. Become. In the normal detection mode, fuel leakage cannot be detected in the low temperature operation state, so even if the fuel leakage occurs during the initial period of combustion start by simply switching between the high temperature operation state and the low temperature operation state, the fuel leakage May not be detected promptly.

  The present invention has been made in view of such circumstances, and the purpose thereof is to accurately detect fuel leakage and incomplete combustion while accurately detecting fuel leakage at the beginning of combustion in the combustion section. Another object of the present invention is to provide a gas detection device for a combustion apparatus.

The gas detection device for a combustion apparatus of the present invention changes its electrical characteristics in response to a combustible gas in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature, and the temperature is lower than the high temperature side sensitive temperature. A gas detector whose electrical characteristics change in response to incomplete combustion gas in a low-temperature operating state;
Heating means for heating the gas detector;
The operation of the heating means is controlled so as to alternately and repeatedly switch the gas detector between the high temperature operation state and the low temperature operation state, and combustible in the high temperature operation state based on the electrical characteristics of the gas detector. And a control means for executing a normal detection mode for detecting a property gas and detecting an incomplete combustion gas in the low-temperature operating state,
The first characteristic configuration is a comparison in which the control means is set to be equal to or less than the initial detection set time during the initial detection set time after receiving the combustion start operation of the combustion unit for burning the supplied fuel. The number of times that the combustible gas is detected in the high temperature operation state during the set time for operation is set to be larger than that in the normal detection mode, and the combustible gas is detected in the high temperature operation state based on the electrical characteristics of the gas detector. An initial detection mode for controlling the operation of the heating means to switch the gas detector between the high temperature operation state and the low temperature operation state in order to detect and detect incomplete combustion gas in the low temperature operation state; It is configured to execute prior to the detection mode.

That is, the control means executes the initial detection mode prior to the normal detection mode for the initial detection set time after accepting the combustion start operation of the combustion section.
In the initial detection mode, the control means increases the number of times that the combustible gas is detected in the high-temperature operation state during the comparison setting time set to be equal to or less than the initial detection setting time than in the normal detection mode. The gas detector is switched between the high temperature operation state and the low temperature operation state in order to detect the combustible gas in the high temperature operation state and detect the incomplete combustion gas in the low temperature operation state based on the electrical characteristics of the gas detection body. .
Incidentally, the command to start combustion in the combustion section, the execution of ignition processing based on the command to start combustion, and the like correspond to accepting a combustion start operation in the combustion section.
The initial detection set time is set to include the initial combustion start period.

In other words, the initial detection mode is executed during the initial combustion start period, and the number of times the combustible gas is detected during the comparison set time is greater than that in the normal detection mode. Since complete combustion gas detection is performed, if a fuel leak occurs during the initial period of combustion start, it is possible to quickly detect the fuel leak, and if incomplete combustion occurs, Incomplete combustion can be detected.
By the way, considering only the quick detection of fuel leakage, it is assumed that the gas detector is set to a high temperature operating state during the initial period of combustion start and only combustible gas detection is performed. However, in this case, even if incomplete combustion occurs during the initial combustion start period, the incomplete combustion cannot be detected.
Accordingly, it is possible to provide a gas detection device for a combustion apparatus that can accurately detect fuel leakage and incomplete combustion while accurately detecting fuel leakage at the beginning of combustion in the combustion section. It was.

In addition to the first characteristic configuration described above, the second characteristic configuration of the gas detection device for the combustion device includes:
In the form in which the control means increases the frequency of setting the high-temperature operation state in the comparative setting time in the initial detection mode as compared with the normal detection mode, the gas detector is placed in the high-temperature operation state and the low-temperature operation state. The operation of the heating means is controlled so as to be alternately and repeatedly switched.

That is, in the initial detection mode, the gas detector is alternately switched between the high temperature operation state and the low temperature operation state, but the frequency of the high temperature operation state in the comparison set time is higher than that in the normal detection mode. The detection of incomplete combustion gas is repeatedly executed while increasing the number of times of detection of combustible gas during the set time for use in comparison with the normal detection mode.
Accordingly, it is possible to accurately detect a fuel leak at the beginning of combustion in the combustion section, and to accurately detect incomplete combustion at the beginning of combustion in the combustion section.

In addition to the second feature configuration, the third feature configuration of the gas detection device for the combustion device includes:
In the initial detection mode, the control means shortens the time for the high temperature operation state to be shorter than the normal detection mode, thereby setting the frequency for the high temperature operation state in the comparison set time to be higher than that for the normal detection mode. It is in the point where it is constituted so as to increase.

That is, by setting the time for the high temperature operation state to be shorter than that for the normal detection mode, the frequency for setting the high temperature operation state in the comparative set time can be increased more than that for the normal detection mode.
That is, in the initial detection mode, it is possible to increase the frequency of the high temperature operation state in the comparative setting time as compared to the normal detection mode while setting the low temperature operation state in the same manner as in the normal detection mode. It can be avoided that the frequency of the low-temperature operation state is lower than that in the normal mode.
Therefore, it is possible to accurately detect fuel leakage and incomplete combustion at the beginning of combustion in the combustion section.

In addition to the second or third feature configuration described above, the fourth feature configuration of the gas detection device for the combustion device includes:
In the initial detection mode, the control means shortens the time for the low temperature operation state to be shorter than the normal detection mode, thereby setting the frequency of setting the high temperature operation state in the comparison set time to be higher than that for the normal detection mode. It is in the point where it is constituted so as to increase.

That is, by shortening the time for setting the low temperature operation state to be shorter than that for the normal detection mode, the time for setting the relatively high temperature operation state is lengthened, and the frequency of setting the high temperature operation state in the comparative set time is higher than that for the normal detection mode. Can do a lot.
And in the initial detection mode, since the time of the high temperature operation state is relatively long, in the initial detection mode, the number of times that the combustible gas is detected in the high temperature operation state can be increased more than the normal detection mode, The number of times that the combustible gas is detected in the initial detection mode can be further increased.
Therefore, it is possible to detect the fuel leakage at the beginning of combustion in the combustion section more accurately.

In addition to any one of the second to fourth characteristic configurations described above, the fifth characteristic configuration of the gas detection device for the combustion apparatus is as follows:
The number of times that the control means executes the process of detecting the combustible gas in the single high temperature operation state in the initial detection mode, and the process of detecting the combustible gas in the single high temperature operation state in the normal detection mode. The configuration is such that the number of executions is larger than the number of executions.

That is, in the initial detection mode, the frequency of the high temperature operation state in the set time for comparison is higher than that in the normal detection mode, and the number of times the combustible gas detection process is executed in the single high temperature operation state is normally detected. Since it becomes more than the mode, the number of times of detecting the combustible gas in the initial detection mode can be further increased.
Therefore, the fuel leakage at the beginning of combustion in the combustion section can be detected more accurately.

In addition to any one of the first to fifth characteristic configurations described above, the sixth characteristic configuration of the gas detection device for a combustion device is as follows:
In the normal detection mode, the control means energizes the gas detection body by energizing the heating means at a voltage lower than a voltage energizing the heating means to switch the gas detection body to the high temperature operation state. The gas detector is switched to the low temperature operation state by switching to the low temperature operation state and stopping the energization of the heating means in the initial detection mode.

  That is, in the normal detection mode, the control means switches the gas detection body to the low temperature operation state by energizing the heating means at a voltage lower than the voltage applied to the heating means to switch the gas detection body to the high temperature operation state. In the initial detection mode, the gas detector is switched to the low temperature operation state by stopping the energization of the heating means.

In other words, in the normal detection mode, the gas detector is switched to the low temperature operating state by applying a voltage to the heating means that is lower than the voltage for switching the gas detector to the high temperature operating state. The temperature can be adjusted to an appropriate temperature to detect complete combustion gas.
Further, in the initial detection mode, the gas detector is switched to the low temperature operation state by stopping the energization to the heating means, so that the temperature decrease of the gas detector can be accelerated, and during the comparison set time In order to increase the number of times that combustible gas is detected in the high temperature operation state than in the normal detection mode, for example, even if the time for the low temperature operation state is shortened, the temperature of the gas detector is detected as incomplete combustion gas. The temperature can be set appropriately.
Therefore, it is possible to accurately detect the fuel leakage at the beginning of the combustion in the combustion section, and also to accurately detect the incomplete combustion at the beginning of the combustion.

A combustion apparatus of the present invention includes a gas detection device for a combustion apparatus having any one of the first to sixth characteristic configurations described above,
The characteristic configuration is that air outside the casing sucked through an intake port provided in the casing housing the combustion section is supplied to the combustion section as combustion air, and combustion gas of the combustion section is provided in the casing. Blowing means that ventilate so as to blow out of the casing from the blowout port provided,
The gas detector is provided at or near the intake port so as to be sensitive to flammable gas and incomplete combustion gas in the air sucked through the intake port.

That is, when the specific example of the combustion device provided with the gas detection device is a fan heater that uses gas fuel or liquid fuel as fuel, the air outside the casing sucked through the intake port is supplied to the burner as combustion air by the blowing means. In addition, the heating target space is heated by blowing the combustion gas of the burner out of the casing through the outlet provided in the casing.
And since the gas detection body is provided in the inlet or the vicinity of the inlet so as to be sensitive to the flammable gas and incomplete combustion gas in the air sucked through the inlet, it is included in the air in the space to be heated. Combustible gas and incomplete combustion gas can be detected, and fuel leakage and incomplete combustion can be detected based on the detected information.
In addition, as described above in the first characteristic configuration of the gas detection device, if a fuel leak occurs during the initial combustion start period, it is possible to quickly detect the fuel leak, and incomplete combustion is prevented. When it occurs, it becomes possible to detect the incomplete combustion.
Accordingly, it is possible to provide a combustion apparatus capable of accurately detecting fuel leakage and incomplete combustion while accurately detecting fuel leakage at the beginning of combustion in the combustion section.

[First Embodiment]
Hereinafter, a first embodiment when the present invention is applied to a gas detection device for a gas fan heater as a combustion device will be described.
As shown in FIG. 1, the gas detection device A has an electrical resistance as an electrical characteristic in response to a combustible gas (gas fuel in the first embodiment) in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature. A gas detector 1 that changes and has an electrical resistance that changes in response to incomplete combustion gas (carbon monoxide) in a low-temperature operating state that is lower than the high-temperature-side sensitive temperature, and heats the gas detector 1 The operation of the heater 2 is controlled so as to alternately and repeatedly switch the heater 2 as the heating means and the gas detector 1 between a high temperature operation state and a low temperature operation state, and the high temperature based on the electrical characteristics of the gas detector 1 A sensor control unit 16 is provided as a control means for executing a normal detection mode in which combustible gas is detected in the operating state and incomplete combustion gas is detected in the low temperature operating state.

As shown in FIG. 2, in addition to the gas detector 1 and the heater 2, the gas sensor S includes the detection electrode 3 and the like.
The heater 2 and the detection electrode 3 are embedded in the gas detector 1. In the first embodiment, a coiled heater combined electrode 4 and a central electrode 5 penetrating through the center of the heater combined electrode 4 are embedded in the gas detector 1, and the heater combined electrode 4 and the central electrode 5 Is made to function as the detection electrode 3 and the heater combined electrode 4 is made to function as the heater 2. Incidentally, the heater combined electrode 4 and the center electrode 5 are composed of noble metal wires such as platinum alloy wires.

The high-temperature sensitive temperature at which the gas detector 1 is in a high temperature operating state is such that the change in electrical resistance when adsorbing flammable gas is more selective than the change in electrical resistance when adsorbing incomplete combustion gas. The temperature at which the temperature of the gas detector 1 becomes a low temperature operating state is such that the change in electrical resistance during incomplete combustion gas adsorption is greater than the change in electrical resistance during flammable gas adsorption. The temperature increases to such an extent that the incomplete combustion gas can be selectively detected.
Specific examples of the high temperature side sensitive temperature at which the gas detector 1 is in a high temperature operating state and the temperature at which the gas detector 1 is in a low temperature operating state are the gas detection accuracy required for the combustion device, fuel leakage, and incomplete combustion. It is set as appropriate according to the gas concentration or the like for executing a safe operation against the above. For example, the high temperature side sensitive temperature is 400 ° C., and the temperature at which the low temperature operation state is achieved is 80 to 100 ° C.

The gas detector 1 is formed of a sintered body of a metal oxide semiconductor such as tin oxide (SnO ₂ ). The gas detector 1 is formed into a flat plate shape, a spherical shape (including an elliptical sphere), etc. In this embodiment, the major axis direction diameter is about 0.5 mm and the minor axis direction diameter is about 0.3 mm. It is formed in an oval shape.
The metal oxide semiconductor carries a catalyst for reducing sensitivity to other gases other than combustible gas and incomplete combustion gas. Examples of the catalyst include Pd, W, Pt, Rh, Ce, Mo, and V. 1 type or 2 types or more of these catalysts are used.
In this embodiment, Pd is used as the catalyst. When Pd is used as the catalyst in this way, after the gas detector 1 adsorbs the gas, the time until the electric resistance changed by the gas adsorption is stabilized is shortened. As a result, the response of the gas detector 1 is improved.

  As shown in FIGS. 2 and 3, the gas sensor S supports the gas detector 1 in a state where the gas detector 1 is connected to three terminals 7a, 7b, 7c penetrating the front and back of the generally disk-shaped base 6, and the base 6 is provided with a substantially cylindrical inner case 8 opened at both ends in a state of accommodating the gas detector 1 inside, and a substantially cylindrical housing having an opening on one end side as a gas inlet 9. 10 is provided on the back side of the base 6 so as to cover the inner case 8.

As shown in FIG. 2, both ends of the heater electrode 4 are separately connected to two heater terminals 7a, 7b of the three terminals 7a, 7b, 7c, and the remaining one detection terminal. One end of the center electrode 5 is connected to 7c.
As shown in FIG. 3, the housing 10 is longer than the inner case 8, and the housing 10 is provided with an opening on the side opposite to the gas introduction port 9 fitted to the base 6. .
A metal mesh 11 made of stainless steel or the like is stretched at the gas inlet 9 of the housing 10, and a filter 12 is provided between the upper portion of the inner case 8 and the metal mesh 11 in the housing 10 to remove miscellaneous gases. Yes.
The filter 12 is formed of, for example, activated carbon, silica gel, or a material that combines these activated carbon and silica gel.
The filter 12 removes miscellaneous gas (for example, NOx, gas of organic solvent such as alcohol, silicon vapor) contained in the gas flowing into the inner case 8 from the gas inlet 9.

  FIG. 4 shows an equivalent circuit of the gas sensor S, Rh shows the electric resistance of the heater combined electrode 4, and Rs shows the electric resistance of the gas detector 1 between the center electrode 5 and one end of the heater combined electrode 4. Show. The electric resistance Rs of the gas detector 1 changes when the combustible gas is adsorbed on the gas detector 1 in the high temperature operating state or when the incomplete combustion gas is adsorbed on the gas detector 1 in the low temperature operating state. It will be.

  As shown in FIG. 1, in addition to the gas sensor S and the sensor control unit 16, the gas detection device A includes a constant voltage circuit 13 that obtains a DC voltage Vc by stepping down and rectifying and smoothing a commercial AC power supply. The switching element 14 for controlling the pulse width of the voltage applied to the heater serving electrode 4 and the load resistor 15 for dividing the output voltage of the constant voltage circuit 13 with the gas detector 1 are provided.

The constant voltage circuit 13 supplies driving power to the heater 2 and the sensor control unit 16.
The positive side of the constant voltage circuit 13 is connected to the collector of the switching element 14, and one end of the heater serving electrode 4 is connected to the emitter of the switching element 14 via the heater terminal 7 a. The end is connected to the negative side of the constant voltage circuit 13 via the heater terminal 7b.
One end of the load resistor 15 is connected to the center electrode 5 of the gas sensor S via the detection terminal 7c, and the other end is connected to the + side of the constant voltage circuit 13.
Further, a resistor 17 and a thermistor 18 that detects the ambient temperature of the gas detector 1 are connected in series between the + side and the − side of the constant voltage circuit 13.

The sensor control unit 16 is configured to control the pulse width of switching of the switching element 14 and to detect fuel leakage and incomplete combustion based on the resistance change of the gas detector 1, and the sensor control unit 16 The drive circuit 19, the A / D conversion circuit 20, the signal processing circuit 21, the temperature signal conversion circuit 22, the output circuit 23, the memory 24, and the like are provided.
The drive circuit 19 is connected to the base of the switching element 14 via the resistor 25 and controls the switching of the switching element 14 with a pulse width.
The A / D conversion circuit 20 is connected to the center electrode 5 of the gas sensor S via the detection terminal 7c, and is connected to the voltage across the heater electrode 4 and the center electrode 5 of the gas detector 1 (hereinafter referred to as the detection voltage). A) may be A / D converted and output to the signal processing circuit 21. That is, this detection voltage corresponds to the detection information of combustible gas and the detection information of incomplete combustion gas.
The temperature signal conversion circuit 22 generates a temperature signal corresponding to the ambient temperature by A / D converting the partial pressure applied to the resistor 17 and outputs the temperature signal to the signal processing circuit 21.

The signal processing circuit 21 corrects the temperature of the detection voltage of the gas detector 1 output from the A / D conversion circuit 20 based on the temperature signal output from the temperature signal conversion circuit 22, and uses the temperature-corrected detection voltage. Based on this, fuel leakage and incomplete combustion are determined.
The output circuit 23 outputs a fuel leakage detection signal to a main control unit 42 of a gas fan heater, which will be described later, when the signal processing circuit 21 determines fuel leakage, and when the signal processing circuit 21 determines incomplete combustion. An incomplete combustion detection signal is output to the main control unit 42.

  As shown in FIG. 1, the gas fan heater includes a burner 41 (see FIG. 10) as a combustion unit that burns supplied gas fuel, and fuel interrupting means V that intermittently supplies the gas fuel to the burner 41. The gas detector A that detects fuel leakage and incomplete combustion of the burner 41, a main control unit 42 that controls the operation of the gas fan heater, and an operation unit 43 that commands various control commands to the main control unit 42. Etc. are provided.

As shown in FIG. 10, the burner 41 is housed in a casing 46 having an intake port 44 on the upper side of the back surface and an outlet 45 on the lower side of the front surface. Inside the casing 46, air outside the casing sucked through the intake port 44 is supplied to the burner 41 as combustion air, and the combustion gas of the burner 41 is ventilated so as to blow out from the outlet 45 to the outside of the casing. A blower 47 is provided as a blowing means.
In the casing 46, a part of the air outside the casing sucked through the intake port 44 is supplied to the burner 41 as combustion air, and the remainder is mixed with the combustion gas of the burner 41 and led to the blowout port 45. In addition, an internal air passage 48 is formed. The blower 47 is provided in the casing 46 with the discharge portion facing the blowout port 45 in a state of sucking the intake port 44.
That is, the combustion gas of the burner 41 is mixed with the air in the space to be heated sucked through the intake port 44 to generate hot air, and the warm air is blown out from the outlet 45 to the space to be heated to heat the space to be heated. Is configured to do.
An air filter 49 is provided at the intake port 44.

  And the gas sensor S is provided in the inlet port 44 of the casing 46 so that the gas detection body 1 may be sensitive to the combustible gas and incomplete combustion gas in the air sucked through the inlet port 44.

As shown in FIGS. 1 and 10, an igniter 50 for igniting the burner 41 and a thermocouple 51 for detecting the ignition of the burner 41 are provided. Further, the fuel supply passage 52 for supplying gas fuel to the burner 41 has an electromagnetic on-off valve 53 for opening and closing the fuel supply passage 52 and an electromagnetic proportional valve 54 for adjusting the amount of fuel supplied to the burner 41. The on / off valve 53 and the proportional valve 54 constitute a fuel interrupting means V.
The fuel supply path 52 is connected to, for example, a city gas pipe (not shown) to which city gas (gas such as 13A, which is mainly composed of methane gas (CH ₄ )) is supplied. In this embodiment, methane gas is mainly used. City gas as a component is supplied to the burner 41.

The operation unit 43 includes an operation switch 55 that commands operation start and stop of the gas fan heater, an alarm lamp 56 that is turned on when fuel leakage or incomplete combustion occurs, and a temperature setting unit that sets a heating target temperature (illustrated). (Not shown), a display unit (not shown) for displaying various information such as the heating target temperature and the room temperature is provided.
The operation switch 55 is configured so that an operation start and an operation stop are instructed alternately every time the pressing operation is repeated.

Hereinafter, control operations of the sensor control unit 16 and the main control unit 42 will be described.
The sensor control unit 16 and the main control unit 42 are both configured using a microcomputer, and are configured to be able to communicate control information with each other in a wired or wireless manner.
As shown in the time chart of FIG. 5, when the operation start is commanded by the operation switch 55, the main control unit 42 waits for the blow standby setting time T <b> 1 to elapse and the blower 47. When the pre-purge set time T2 has elapsed after the blower 47 is activated, an ignition process is performed to activate the igniter 50 and open the on-off valve 53 and the proportional valve 54 to ignite the burner 41. After the output voltage of the pair 51 reaches the ignition detection level and the ignition of the burner 41 is detected, the operation of the igniter 50 is stopped when the forced spark set time T3 elapses.
After the ignition of the burner 41 is detected, the main control unit 42 adjusts the opening of the proportional valve 54 so that the detected temperature of a room temperature sensor (not shown) that detects the temperature of the heating target space becomes the heating target temperature. After performing the combustion amount adjustment control for adjusting the combustion amount of 41, and when the operation stop is instructed by the operation switch 55, after performing the fire extinguishing process for closing the open / close valve 53 and the proportional valve 54 and extinguishing the burner 41 The blower 47 is stopped when the post-purge setting time T4 has elapsed.

The main control unit 42 first operates the igniter 50 when the pre-purge setting time T2 elapses after the blower 47 is operated, and when the valve opening standby setting time T5 elapses after the igniter 50 is operated, the on-off valve 53 The ignition process is executed in such a manner that the proportional valve 54 is opened.
Although not shown in the figure, the main control unit 42, based on the output voltage of the thermocouple 51, after the start of operation is instructed by the operation switch 55 and before the set time T <b> 1 for blowing standby elapses. It is configured to execute a thermocouple failure determination process for determining the failure.

  Incidentally, each of the set time T1 for waiting for air blow and the set time T2 for pre-purge is set so that, for example, the combined time becomes a time in the range of 4 to 7 seconds. The post purge setting time T4 is set to a time in the range of 100 to 160 seconds, and the forced spark setting time T3 and the valve opening standby setting time T5 are set to a time shorter than 1 second.

Next, the control operation of the sensor control unit 16 will be described.
The temperature of the gas detector 1 is adjusted by the sensor control unit 16 by performing pulse width control of switching of the switching element 14 and duty control of energization to the heater 2.

As shown in the time chart of FIG. 6, after the start of operation is commanded by the operation switch 55, the sensor control unit 16 performs the pre-ignition detection mode during the pre-ignition period until the main control unit 42 executes the ignition process. After the ignition process is started, the initial detection mode is executed for the initial detection set time T6. After the initial detection mode, the normal detection mode is executed until the operation stop command is issued by the operation switch 55. To do.
Incidentally, FIG. 6 shows the timing of the operation start command and the operation stop command by the operation switch 55, the timing of controlling the voltage applied to the heater 2 for switching the gas detector 1 between the high temperature operation state and the low temperature operation state, and the high temperature The timing chart of the fuel leakage detection process in the operating state and the timing of the incomplete combustion detection process in the low temperature operation state are shown in association with each other, and the gas accompanying the switching between the high temperature operation state and the low temperature operation state is shown. The temperature change of the detection body 1 is also shown in association with it. In FIG. 6, each point indicates the timing of the fuel leak detection process and the timing of the incomplete combustion detection process.

First, the normal detection mode will be described.
In the normal detection mode, the sensor control unit 16 controls the operation of the heater 2 so that the gas detector 1 is alternately and repeatedly switched between a high temperature operation state and a low temperature operation state, and the electrical characteristics of the gas detector 1 are changed. Based on this, the combustible gas is detected in the high temperature operation state, the fuel leakage is detected by the detection information, and the incomplete combustion gas is detected in the low temperature operation state, and the incomplete combustion of the burner 41 is detected by the detection information. It is configured.

In this normal detection mode, the high temperature side sensitive temperature is set to 400 ° C., for example, and in the low temperature operating state, the temperature of the gas detector 1 is adjusted to the low temperature side sensitive temperature of, for example, 80 ° C.
Further, the normal high temperature action setting time T _H1 for controlling the operation of the heater 2 to set the gas detector 1 to a high temperature operation state is set to 5 seconds, for example, and the heater 2 of the heater 2 is set to a low temperature operation state. The normal low-temperature action setting time T _L1 for controlling the operation is set to 20 seconds, for example.
Note that the time during which the operation of the heater 2 is controlled to bring the gas detector 1 into the high temperature operation state (for example, the normal high temperature action setting time T _H1 in this normal detection mode) corresponds to the high temperature operation state. The time during which the operation of the heater 2 is controlled to bring the detector 1 into the low temperature operation state (for example, the normal low temperature action setting time T _L1 in this normal detection mode) corresponds to the low temperature operation state.

  In addition, the timing of the fuel leak detection process for detecting fuel leaks based on the detection information of flammable gas in the high temperature operation state is set at the end of the high temperature operation state, and the incomplete combustion gas detection information is incomplete in the low temperature operation state. The timing of the incomplete combustion detection process for detecting combustion is set at the end of the low temperature operation state.

That is, in this normal detection mode, the sensor control unit 16 is applied to the heater 2 in order to adjust the temperature of the gas detector 1 to the high temperature side sensitive temperature of 400 ° C. during the normal high temperature action setting time T _H1. The gas detector 1 is put into a high temperature operating state by duty-controlling the energization of the heater 2 so that the average power to be 120 mW, and a fuel leak detection process is executed at the end of the high temperature operating state. Further, the sensor control unit 16 sets the average of the electric power applied to the heater 2 to 12 mW in order to adjust the temperature of the gas detector 1 to the low temperature side sensitive temperature of 80 ° C. during the normal low temperature action setting time T _L1. Thus, by performing duty control on energization to the heater 2, the gas detector 1 is brought into a low temperature operation state, and the incomplete combustion detection process is executed at the end of the low temperature operation state.
The heater 2 may be energized with a constant DC voltage without using duty control. Further, an FET may be used for the switching element 14.

Next, the initial detection mode will be described.
In the initial detection mode, the sensor control unit 16 receives the combustion start operation of the burner 41, and then during the initial detection set time, during the comparison set time T7 set to be equal to or less than the initial detection set time T6. The number of times that the combustible gas is detected in the high temperature operation state is increased from that in the normal detection mode. Based on the electrical characteristics of the gas detector 1, the combustible gas is detected in the high temperature operation state, and the fuel leaks based on the detection information. In order to detect the incomplete combustion gas in the low temperature operation state and detect the incomplete combustion based on the detection information, the heater 2 is operated so as to switch the gas detector 1 between the high temperature operation state and the low temperature operation state. Control.
In other words, in the first embodiment, starting the ignition process by the main control unit 42 corresponds to accepting a combustion start operation of the burner 41, and the sensor control unit 16 accepts a combustion start operation of the burner 41. Thereafter, during the initial detection set time T6, the initial detection mode is configured to be executed prior to the normal detection mode.

In the first embodiment, the sensor control unit 16 operates the gas detector 1 at a high temperature in the initial detection mode so that the frequency of setting the high temperature operation state at the comparison set time T7 to be higher than that in the normal detection mode. The operation of the heater 2 is controlled to alternately and repeatedly switch between the state and the low temperature operation state.
In addition, the sensor control unit 16 increases the frequency of setting the high temperature operation state in the comparison setting time T7 in the initial detection mode to be shorter than that in the normal detection mode by shortening the time for setting the low temperature operation state in the initial detection mode. It is configured as follows.

Specifically, in this initial detection mode, the initial high temperature action setting time T _H2 for bringing the gas detector 1 into a high temperature operating state is set to the same 5 seconds as the normal high temperature action setting time T _H1. The initial low temperature action setting time T _L2 for setting the gas detector 1 in the low temperature operation state is set to 2 seconds, which is shorter than the normal low temperature action setting time T _L1 of 20 seconds.
Then, the initial detection set time T6 is set to a time longer than the time required for the burner 41 to be ignited after the ignition process is started, for example, 33 seconds, and the comparison set time T7 is set to the initial detection set time. The same time as T6 is set.
In other words, the frequency of the high temperature operation state in the comparison set time T7 is five times in the initial detection mode, and is configured to be higher than the maximum twice in the normal detection mode.

Further, in the first embodiment, the number of times that the sensor control unit 16 executes the process of detecting the combustible gas in the single high temperature operation state in the initial detection mode is set to the number of times in the single detection operation mode. It is comprised so that it may increase more than the frequency | count of performing the process which detects combustible gas.
In this initial detection mode, the high temperature side sensitive temperature is set to 400 ° C., which is the same as the high temperature side sensitive temperature in the normal detection mode.
As shown in FIG. 6, when the high temperature side sensitive temperature is set to 400 ° C., the temperature of the gas detector 1 becomes high in about 1 second after the energization of the heater 2 is started and the high temperature operation state is started. Raises to side sensitive temperature.
Therefore, in the initial detection mode, the timing of the fuel leak detection process is set every second after the start of the high temperature operation state, and the number of times of the fuel leak detection process in the single high temperature operation state is set to, for example, four times. ing.
That is, the number of times of fuel leak detection processing in a single high-temperature operation state is four in the initial detection mode, and is larger than one in the normal detection mode.

Since the initial low temperature action setting time T _L2 in the initial detection mode is set shorter than the normal low temperature action setting time T _{L1 in} the normal detection mode, the temperature of the gas detector 1 in the low temperature operation state in the initial detection mode In the low temperature operation state in the normal detection mode, and in the initial detection mode, the energization of the heater 2 is stopped to switch to the low temperature operation state in the initial detection mode. In the operating state, the temperature of the gas detector 1 is configured so as to be the case.
In the initial detection mode, the timing of the incomplete combustion detection process is set to the end point of the low temperature operation state.

  By setting the operation mode of the initial detection mode as described above, in the initial detection mode, the number of times of the fuel leakage detection process in the set time for comparison T7 is set to 20 times, for example, and the number of times in the normal detection mode. For example, it is configured to be more than twice.

That is, in this initial detection mode, the sensor control unit 16 is applied to the heater 2 to adjust the temperature of the gas detector 1 to the high temperature side sensitive temperature of 400 ° C. during the initial high temperature action setting time T _H2. The gas detector 1 is placed in a high temperature operating state by duty-controlling the energization of the heater 2 so that the average power is 120 mW, and a fuel leak detection process is executed every second after the high temperature operating state is started. To do. Further, the sensor control unit 16 stops the energization of the heater 2 during the initial low temperature action setting time T _L2 , thereby bringing the gas detector 1 into a low temperature operation state, and incomplete at the end of the low temperature operation state. The combustion detection process is executed.

Next, the pre-ignition detection mode will be described.
In the pre-ignition detection mode, the sensor control unit 16 controls the operation of the heater 2 so as to bring the gas detector 1 into a high-temperature operation state, and detects combustible gas based on the electrical characteristics of the gas detector 1. Then, a fuel leak detection process for detecting a fuel leak based on the detection information is executed.

As shown in FIG. 5, the length of the pre-ignition period is set to a time that is a sum of the blow standby setting time T1 and the pre-purge setting time T2, that is, a time in the range of 4 to 7 seconds.
In this pre-ignition detection mode, the high temperature side sensitive temperature is set to 400 ° C., which is the same temperature as the high temperature side sensitive temperature in the normal detection mode.
In addition, the timing of the fuel leak detection process is set 1 second after the start of the high-temperature operation state, and further, the timing of the fuel leak detection process is set every 1 second thereafter. In the first embodiment, it is configured to be executed 4 times).

  That is, in this pre-ignition detection mode, the sensor control unit 16 adjusts the temperature of the gas detector 1 to a high-temperature side sensitive temperature of 400 ° C. so that the average of the power applied to the heater 2 is 120 mW. By performing duty control on energization to the heater 2, the gas detector 1 is put into a high temperature operation state, and after the start of the high temperature operation state, a fuel leak detection process is executed every second.

Hereinafter, a method for detecting fuel leakage based on the detection information of the combustible gas in the fuel leakage detection processing, and a method for detecting incomplete combustion based on the detection information of the incomplete combustion gas in the incomplete combustion detection processing, Add a description.
The result of examining the relationship between the methane concentration in the air and the resistance Rs of the gas detector 1 when the temperature of the gas detector 1 is 400 ° C., which is the high-temperature sensitive temperature, is as shown in FIG. The higher the concentration, the lower the resistance Rs of the gas detector 1, and the resistance Rs of the gas detector 1 corresponds to the methane concentration.
Corresponding to the resistance Rs (about 1.1 kΩ) of the gas detector 1 when the fuel leakage detection concentration, which is the methane concentration for detecting fuel leakage, is set to 3000 ppm, for example, and the methane concentration is the fuel leakage detection concentration. The detected voltage is set to the fuel leakage detection voltage, and the fuel leakage detection voltage is stored in the memory 24 of the sensor control unit 16.

The relationship between the carbon monoxide concentration in the air and the resistance Rs of the gas detector 1 was examined when the temperature of the gas detector 1 was 80 ° C., which is the temperature when performing the incomplete combustion detection process in the normal detection mode. The result is as shown in FIG. 8, and the higher the carbon monoxide concentration, the lower the resistance Rs of the gas detector 1, and the resistance Rs of the gas detector 1 corresponds to the carbon monoxide concentration.
The incomplete combustion detection concentration, which is the carbon monoxide concentration for detecting incomplete combustion, is set to, for example, 300 ppm, and the resistance Rs of the gas detector 1 when the carbon monoxide concentration is the incomplete combustion detection concentration (about The detection voltage corresponding to 7.5 kΩ is set to the incomplete combustion detection voltage, and the incomplete combustion detection voltage is stored in the memory 24 of the sensor control unit 16.

The sensor control unit 16 is configured to detect that a fuel leak has occurred when the detected voltage becomes equal to or higher than the fuel leak detection voltage in the pre-ignition detection mode, and transmit a fuel leak detection signal to the main control unit 42. Has been.
Further, in the normal detection mode, the sensor control unit 16 detects that incomplete combustion has occurred when the detected voltage becomes equal to or higher than the voltage for detecting incomplete combustion in the low temperature operation state, and generates an incomplete combustion detection signal as a main signal. It is transmitted to the control unit 42 and configured to transmit a fuel leak detection signal to the main control unit 42 by detecting that a fuel leak has occurred when the detected voltage becomes equal to or higher than the fuel leak detection voltage in a high temperature operating state. ing.

As described above, in the low-temperature operation state in the initial detection mode, the temperature of the gas detector 1 becomes a result, and the lowest temperature is approximately 100 ° C. as shown in FIG.
The result of examining the relationship between the carbon monoxide concentration in the air and the resistance Rs of the gas detector 1 when the temperature of the gas detector 1 is 100 ° C. is as shown in FIG. The carbon monoxide concentration when the resistances Rs are the same is higher in the initial detection mode than in the normal detection mode.
When the temperature of the gas detector 1 is 100 ° C., for example, when the resistance Rs of the gas detector 1 is 7.5 kΩ when detecting incomplete combustion in the normal detection mode, the carbon monoxide concentration is about 1000 ppm.
The carbon monoxide concentration of 1000 ppm is sufficiently low to detect incomplete combustion without impairing safety.
Therefore, in the initial detection mode, the sensor control unit 16 detects that incomplete combustion has occurred when the detection voltage becomes equal to or higher than the incomplete combustion detection voltage in the low temperature operation state, and generates an incomplete combustion detection signal. It is configured to transmit to the main control unit 42.
In the initial detection mode, the sensor control unit 16 detects that a fuel leak has occurred when the detected voltage becomes equal to or higher than the fuel leak detection voltage in the high temperature operation state, and sends a fuel leak detection signal to the main control unit 42. Configured to send to.

  The incomplete combustion detection voltage in the initial detection mode is the detection voltage corresponding to the resistance Rs (about 36 kΩ) of the gas detector 1 when the carbon monoxide concentration is 300 ppm, which is the incomplete combustion detection concentration in the normal detection mode. It may be set to.

If a fuel leak detection signal is transmitted from the sensor control unit 16 during the pre-ignition period after the start of operation is commanded until the ignition process is executed, the main control unit 42 does not execute the ignition process. The alarm lamp 56 is turned on.
Further, when the fuel leak detection signal is transmitted from the sensor control unit 16 after the ignition process is started, the main control unit 42 executes a fire extinguishing process for closing the on-off valve 53 and the proportional valve 54, and an alarm lamp. After the 56 is turned on, the blower 47 is stopped when the post-purge setting time T4 elapses.
In addition, the main control unit 42 executes a fire extinguishing process for closing the on-off valve 53 and the proportional valve 54 when an incomplete combustion detection signal is transmitted from the sensor control unit 16 after the ignition process is started. In addition, after the alarm lamp 56 is turned on, the blower 47 is stopped when the post-purge setting time T4 elapses.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described based on the drawings.
In the second embodiment, another embodiment of the control operation of the sensor control unit 16 will be described. Since the overall configuration of the gas fan heater is the same as that of the first embodiment, the sensor control unit 16 is mainly used. Differences from the first embodiment in the control operation will be described.

In the second embodiment, the operation start by the operation switch 55 of the operation unit 43, that is, the command to start the combustion of the burner 41 is equivalent to the reception of the combustion start operation of the burner 41. It is configured.
Then, as shown in the time chart of FIG. 11, after the start of operation is commanded by the operation switch 55, the sensor control unit 16 executes the initial detection mode prior to the normal detection mode for the initial detection set time T6. Is configured to do.

In the second embodiment, the initial detection setting time T6 is set to 40 seconds.
The control operation of the sensor control unit 16 for controlling the operation of the heater 2 to switch the gas detector 1 to the high temperature operation state and the low temperature operation state, and the sensor control unit in each of the fuel leak detection process and the incomplete combustion detection process Since the control operation 16 is the same as that in the first embodiment, the description thereof is omitted.
The initial high temperature action setting time T _H2 for setting the gas detector 1 in the high temperature operation state and the initial low temperature action setting time T _L2 for setting the gas detector 1 in the low temperature operation state are set in the first example. This is the same as the embodiment.

[Another embodiment]
Next, another embodiment will be described.
(A) In the initial detection mode, the form for setting the high temperature operation state and the low temperature operation state is not limited to the form exemplified in each of the first and second embodiments.
That is, in the initial detection mode, the high-temperature operation state is set during the comparison set time T7 so that the number of fuel leak detection processes during the comparison set time T7 can be made larger than that in the normal detection mode. The high temperature operation state and the low temperature operation state may be set in such a manner that the time ratio is larger in the initial detection mode than in the normal detection mode.
For example, during the initial detection setting time T6, the low temperature operation state is set only once so that the time is shorter than the time of one low temperature operation state in the normal detection mode, and the initial detection setting time T6 is set. The remaining time may be set to a high temperature operating state.

(B) As in the first and second embodiments described above, in the case where the frequency of the high temperature operation state at the comparative setting time in the initial detection mode is higher than that in the normal detection mode, The number of times that the fuel leak detection process is executed in the high temperature operation state may be the same as the number of times that the fuel leak detection process is executed in the single high temperature operation state in the normal detection mode.

(C) In the initial detection mode, the configuration of the sensor control unit 16 for increasing the frequency of the high-temperature operation state in the comparative set time T7 as compared with the normal detection mode is the same as that in each of the first and second embodiments. It is not limited to the illustrated configuration, that is, the configuration in which the time for the low temperature operation state is shorter than that in the normal detection mode.
For example, a configuration in which the time for the high temperature operation state is made shorter than the normal detection mode, or a time for the low temperature operation state is made shorter than the normal detection mode and the time for the high temperature operation state is made shorter than the normal detection mode. But it ’s okay.

(D) The timing of the fuel leak detection process in the initial detection mode is not limited to the timing of every second as in the first and second embodiments, and the fuel leak detection process is continuously performed. You may comprise so that it may perform.

(E) The specific setting example of the initial detection setting time T6 is not limited to the time exemplified in the first and second embodiments. For example, the combustion of the burner 41 is stable. The time can be set as appropriate in consideration of the time required until the disappearance hardly occurs.

(F) In each of the first and second embodiments described above, the case where the gas detector 1 is configured to be switched to the low temperature operation state by stopping the energization of the heater 2 in the initial detection mode is exemplified. Alternatively, the gas detector 1 may be switched to the low temperature operation state by energizing the heater 2 with a voltage lower than the voltage for switching the gas detector 1 to the high temperature operation state.

(G) In each of the first and second embodiments described above, the case where the sensor control unit 16 and the main control unit 42 are configured separately has been illustrated. However, the sensor control unit 16 and the main control unit 42 are micro-configured. You may comprise as a single thing using a computer.

(H) The installation location of the gas sensor S is not limited to the intake port 44 of the casing 46 illustrated in the first and second embodiments, and may be, for example, near the intake port 44.

(L) In each of the first and second embodiments described above, the case where the present invention is applied to a gas detection device for a combustion apparatus that uses gas fuel as fuel is exemplified. However, the present invention uses liquid fuel as fuel. The present invention can also be applied to a gas detection device for a combustion device. In this case, the gas detector 1 detects a gas obtained by vaporizing liquid fuel as a combustible gas.
Further, when the present invention is applied to a gas detector for a combustion apparatus that uses gas fuel as fuel, the gas fuel is not limited to city gas mainly composed of methane, and may be propane gas, for example.

(Nu) In addition to the gas fan heater exemplified in the above embodiment, the present invention can be applied to gas detection devices for various combustion devices such as a gas stove, an oil fan heater, an oil stove, and a hot water supply device.

  As described above, it is possible to provide a gas detection device for a combustion device that can accurately detect fuel leakage and incomplete combustion while accurately detecting fuel leakage at the beginning of combustion in the combustion section. it can.

The block diagram of the combustion apparatus provided with the gas detection apparatus which concerns on each 1st and 2nd embodiment The figure which shows the principal part of the gas sensor which concerns on each 1st and 2nd embodiment. Partially cutaway external view of the gas sensor according to each of the first and second embodiments The figure which shows the equivalent circuit of the gas sensor which concerns on each 1st and 2nd embodiment The figure which shows the time chart of the control action of the combustion apparatus which concerns on each 1st and 2nd embodiment The figure which shows the time chart of control operation of the gas detection apparatus which concerns on 1st Embodiment. Diagram showing the relationship between methane concentration and gas detector resistance Diagram showing the relationship between carbon monoxide concentration and resistance of the gas detector in normal detection mode The figure which shows the relationship between the carbon monoxide concentration and the resistance of the gas detector in the initial detection mode Vertical right side view showing a schematic configuration of the combustion apparatus according to each of the first and second embodiments The figure which shows the time chart of control operation of the gas detection apparatus which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas detection body 2 Heating means 16 Control means 41 Combustion part 44 Intake port 45 Outlet port 46 Casing 47 Air blower

Claims (7)

The electrical characteristics change in response to the flammable gas in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature, and in response to incomplete combustion gas in a low temperature operating state where the temperature is lower than the high temperature side sensitive temperature. A gas detector whose electrical characteristics change;
Heating means for heating the gas detector;
The operation of the heating means is controlled so as to alternately and repeatedly switch the gas detector between the high temperature operation state and the low temperature operation state, and combustible in the high temperature operation state based on the electrical characteristics of the gas detector. A gas detection device for a combustion apparatus provided with a control means for detecting a sexual gas and executing a normal detection mode for detecting an incomplete combustion gas in the low temperature operation state,
After the control means accepts the combustion start operation of the combustion section for burning the supplied fuel, the control means during the initial detection set time, during the comparison set time set below the initial detection set time. In a form in which the number of times combustible gas is detected in a high-temperature operation state is greater than that in the normal detection mode, the combustible gas is detected in the high-temperature operation state based on the electrical characteristics of the gas detector and the low-temperature operation state In order to detect incomplete combustion gas, an initial detection mode for controlling the operation of the heating means to switch the gas detector between the high temperature operation state and the low temperature operation state is executed prior to the normal detection mode. A gas detection device for a combustion device configured as described above.   In the form in which the control means increases the frequency of setting the high-temperature operation state in the comparative setting time in the initial detection mode as compared with the normal detection mode, the gas detector is placed in the high-temperature operation state and the low-temperature operation state. The gas detection device for a combustion apparatus according to claim 1, wherein the operation of the heating means is controlled so as to be alternately and repeatedly switched.   In the initial detection mode, the control means shortens the time for the high temperature operation state to be shorter than the normal detection mode, thereby setting the frequency for the high temperature operation state in the comparison set time to be higher than that for the normal detection mode. The gas detection device for a combustion apparatus according to claim 2, wherein the gas detection apparatus is configured to be increased.   In the initial detection mode, the control means shortens the time for the low temperature operation state to be shorter than the normal detection mode, thereby setting the frequency of setting the high temperature operation state in the comparison set time to be higher than that for the normal detection mode. The gas detection device for a combustion apparatus according to claim 2 or 3, wherein the gas detection apparatus is configured to be increased.   The number of times that the control means executes the process of detecting the combustible gas in the single high temperature operation state in the initial detection mode, and the process of detecting the combustible gas in the single high temperature operation state in the normal detection mode. The gas detection device for a combustion apparatus according to any one of claims 2 to 4, wherein the gas detection apparatus is configured to be larger than the number of times of execution.   In the normal detection mode, the control means energizes the gas detection body by energizing the heating means at a voltage lower than a voltage energizing the heating means to switch the gas detection body to the high temperature operation state. The switch to the low temperature operation state, and in the initial detection mode, the gas detector is configured to be switched to the low temperature operation state by stopping energization to the heating means. A gas detection device for a combustion apparatus according to any one of the preceding claims. A combustion apparatus comprising the gas detection device for a combustion apparatus according to any one of claims 1 to 6,
Air outside the casing sucked through an intake port provided in a casing that houses the combustion unit is supplied to the combustion unit as combustion air, and combustion gas in the combustion unit is supplied from a blowout port provided in the casing. Blowing means that ventilate so as to blow out of the casing is provided,
The combustion apparatus provided in the said inlet or the said inlet so that the said gas detection body may respond to the combustible gas and incomplete combustion gas in the air inhaled through the said inlet.

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