JP5243944B2 - Combustion device - Google Patents

Description

The present invention comprises a burner for burning supplied fuel;
A fuel intermittent means capable of switching between a fuel supply state for supplying fuel to the burner and a fuel supply stop state for stopping the supply of fuel to the burner;
A gas detector whose electrical characteristics change in response to fuel;
A control means for performing an ignition process for operating the ignition means for igniting the burner and switching the fuel intermittent means to the fuel supply state when the start of combustion of the burner is commanded,
When the control means executes a fuel leak detection process for detecting a fuel leak based on an electrical characteristic of the gas detector after the ignition process is started, and detects the fuel leak in the fuel leak detection process. The present invention relates to a combustion apparatus configured to switch the fuel interrupting means to the fuel supply stop state.

  Such gas detectors change their electrical characteristics in response to fuel, and based on the electrical characteristics of the gas detectors, fuel leaks, i.e. around the combustion device, where they should not exist. It is comprised so that it may detect that fuel exists (for example, refer patent document 1).

  Then, after the start of the ignition process for igniting the burner, a fuel leak detection process for detecting a fuel leak based on the electrical characteristics of the gas detector is executed, and when the fuel leak is detected in the fuel leak detection process, The fuel interrupting means is switched to the fuel supply stop state so that the fuel supply to the burner is stopped, and safety measures are taken against fuel leakage due to burner ignition mistake or burner extinguishing .

JP 2000-193623 A

By the way, although very rarely, fuel may be present before the ignition process is executed due to a failure of the fuel interrupting means or a poor connection of a pipe for supplying fuel to the burner. The fuel may also be present due to other factors.
However, in the conventional combustion apparatus, since the fuel leakage detection process is executed after the ignition process is started, it is not possible to quickly detect the presence of fuel that may have occurred before the ignition process. There is room for improvement in further improving safety.

  This invention is made | formed in view of this situation, The objective is to provide the combustion apparatus which can further improve the safety | security regarding the ignition of a burner.

The combustion apparatus of the present invention corresponding to claim 2 burns the supplied fuel, and
A fuel intermittent means capable of switching between a fuel supply state for supplying fuel to the burner and a fuel supply stop state for stopping the supply of fuel to the burner;
A gas detector whose electrical characteristics change in response to fuel;
A control means for performing an ignition process for operating the ignition means for igniting the burner and switching the fuel intermittent means to the fuel supply state when the start of combustion of the burner is commanded,
When the control means executes a fuel leak detection process for detecting a fuel leak based on an electrical characteristic of the gas detector after the ignition process is started, and detects the fuel leak in the fuel leak detection process. The fuel intermittent means is configured to switch to the fuel supply stop state,
The first characteristic configuration is configured such that the control means executes the fuel leakage detection process during the first half of ignition from when the start of combustion is commanded to when the ignition process is executed .
The gas detector is sensitive to the fuel in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature, and the electrical characteristics change, and the incomplete combustion gas is in a low temperature operating state where the temperature is lower than the high temperature side sensitive temperature. Is configured to change the electrical characteristics in response to
A heating means for heating the gas detector is provided,
In the pre-ignition period, the control means controls the operation of the heating means to bring the gas detector into the high-temperature operation state, and executes the fuel leak detection process. After the ignition process is started, The operation of the heating means is controlled so that the gas detector is alternately and repeatedly switched between the high temperature operation state and the low temperature operation state, and the fuel is detected in the high temperature operation state based on electrical characteristics of the gas detector. It is configured to execute an incomplete combustion detection process that performs a leakage process and detects incomplete combustion in the low temperature operation state,
The high-temperature operation at the comparison setting time that is set to be equal to or less than the initial detection set time after the initial detection set time has elapsed during the initial detection set time after the ignition process is started. 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 in a state where the frequency of the state is increased.

That is, the control means performs the fuel leakage detection process during the first half of the ignition period from when the start of combustion is commanded to when the ignition process is executed, so even if fuel is present before the ignition process is executed, The presence of the fuel can be detected quickly.
When the fuel is detected by the control means before the ignition process is executed, the control means is configured to execute an alarm process such as actuating the alarm means. Based on the alarm processing that is performed, it becomes possible to take measures against the presence of fuel.
Accordingly, it is possible to provide a combustion apparatus that can further improve the safety of ignition of the burner.

In addition to the first feature configuration, the second feature configuration is
The control means is configured to execute the fuel leak detection processing a plurality of times during the first ignition phase.

In other words, since the control means executes the fuel leak detection process a plurality of times during the first half of the ignition, even if fuel is present before the ignition process is executed, the presence of the fuel can be detected even more quickly. Can do.
Accordingly, it is possible to further improve the safety of ignition of the burner.

In addition to the first or second feature configuration, the third feature configuration is
When the control means detects a fuel leak in the pre-ignition period, it is configured not to execute the ignition process.
In addition, the combustion apparatus of the present invention corresponding to claim 1 comprises all the first to third characteristic configurations.

That is, the control means does not execute the ignition process when it detects the fuel in the pre-ignition period, so that it is possible to reliably prevent the inconvenience that the ignition process is executed despite the presence of fuel.
Accordingly, it is possible to further improve the safety of ignition of the burner.

As in the first characteristic configuration described above , the gas detector is sensitive to the fuel in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature, and changes its electrical characteristics, and in a low temperature operating state where the temperature is lower than the high temperature side sensitive temperature. The electrical characteristics change in response to incomplete combustion gas. By switching the gas detector between a high temperature operation state and a low temperature operation state, fuel leakage and incomplete combustion of the burner can be achieved with one gas detector. Can be detected.
That is, while making it possible to detect both fuel leakage and incomplete combustion, it is possible to reduce the cost of the combustion apparatus.

Then, during the pre-ignition period, the control means controls the operation of the heating means so as to bring the gas detector into a high temperature operating state, and executes a fuel leak detection process.
Further, the control means controls the operation of the heating means so that the gas detector is alternately switched between the high temperature operation state and the low temperature operation state after the ignition process is started, and based on the electrical characteristics of the gas detector. The fuel leakage process is executed in the high temperature operation state, and the incomplete combustion detection process is executed in the low temperature operation state.
In other words, there is no risk of incomplete combustion of the burner before the ignition process, so by performing only the fuel leak detection process, the fuel leak can be detected quickly, and after the ignition process starts. Since incomplete combustion of the burner may occur, it is possible to accurately detect fuel leakage and incomplete combustion by configuring the fuel leakage detection process and the incomplete combustion detection process alternately and repeatedly. be able to.
Accordingly, the safety against both fuel leakage and incomplete combustion can be further improved while reducing the cost of the combustion apparatus.

As in the first characteristic configuration, since an ignition error or extinction is likely to occur during the ignition process or after the ignition process until the combustion of the burner becomes stable, after the ignition process starts, until the combustion becomes stable During the predetermined period, fuel leakage is more likely to occur than incomplete combustion.
And after the start of the ignition process, the gas detector is in a state in which the frequency of the high temperature operation state in the comparative setting time is higher during the initial detection setting time than after the initial detection setting time has elapsed. Since the high-temperature operation state and the low-temperature operation state are alternately and repeatedly switched, if a fuel leak occurs during the initial detection setting time, the fuel leak can be quickly detected.
Therefore, in addition to the effect obtained by the fourth characteristic configuration, it is possible to obtain an effect that the safety against fuel leakage at the initial stage of combustion of the burner can be further improved.

The fourth feature configuration is in addition to any one of the first to third feature configurations,
Air outside the casing sucked through an intake port provided in a casing that houses the burner is supplied to the burner as combustion air, and combustion gas of the burner is discharged from a blowout port provided in the casing to the outside of the casing. Blowing means that ventilate so as to blow out is provided,
The gas detector is provided at or near the intake port so as to be sensitive to fuel in the air sucked through the intake port.

That is, when a specific example of the combustion device is a fan heater using 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, and the The space to be heated is heated by blowing the combustion gas of the burner out of the casing from the outlet provided in the casing.
And since the gas detector is provided near the intake port or in the vicinity of the intake port so as to be sensitive to the fuel in the air sucked through the intake port, it detects the fuel contained in the air in the heating target space, Based on the detection information, it becomes possible to detect the fuel leakage, and it is possible to accurately detect that the safety is lost due to the fuel leakage.
Accordingly, it is possible to provide a combustion apparatus that can further improve the safety of ignition of the burner.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in the case where the present invention is applied to a gas fan heater as a combustion apparatus will be described based on the drawings.
As shown in FIG. 1, the gas fan heater includes a burner 41 for burning supplied gas fuel (see FIG. 10), a fuel supply state for supplying the gas fuel to the burner 41, and supply of the gas fuel to the burner 41. This is generated when the fuel intermittent means V which can be switched to the fuel supply stop state for stopping the fuel, the combustible gas (gas fuel in this embodiment) generated when the fuel leakage occurs, and the burner 41 are incompletely combusted. A gas detection part A for detecting incomplete combustion gas (carbon monoxide), a main control part 42 for controlling the operation of the gas fan heater, an operation part 43 for instructing various control commands to the main control part 42, etc. Configured.

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.

As shown in FIGS. 1 and 10, an igniter 50 as ignition means for igniting the burner 41 and a thermocouple 51 for detecting 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.

  As shown in FIG. 1, the gas detector A includes a gas sensor S including a gas detector 1 whose electrical characteristics change in response to a combustible gas (gas fuel). As shown in FIG. 10, the gas sensor S is provided at the intake port 44 of the casing 46 so as to make the gas detector 1 sensitive to inflammable gas and incomplete combustion gas in the air sucked through the intake port 44. .

In this embodiment, the gas detector 1 is sensitive to the combustible gas in a high temperature operation state where the temperature is equal to or higher than the high temperature side sensitive temperature, and the electrical resistance as an electrical characteristic is changed, and the temperature is higher than the high temperature side sensitive temperature. The electrical resistance is changed in response to incomplete combustion gas in a low temperature operating state.
As shown in FIG. 2, the gas sensor S includes a gas detector 1, a heater 2 as a heating means for heating the gas detector 1, and a detector for measuring electrical characteristics of the gas detector 1. An electrode 3 is provided.

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 action 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 FIG. 2, the heater 2 and the detection electrode 3 are embedded in the gas detector 1. In this embodiment, a coil-shaped heater combined electrode 4 and a center 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 center electrode 5 are detected. The electrode 3 functions as a heater electrode 3, and the heater electrode 4 functions 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.

  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, the gas detection unit A steps down a commercial AC power supply and rectifies and smoothes it to obtain a DC voltage Vc, and the heater sensor electrode 4 of the gas sensor S. Switching element 14 for controlling the pulse width of the voltage applied to the load, load resistor 15 for dividing the output voltage of the constant voltage circuit 13 with the gas detector 1, and switching of the switching element 14 with pulse width control and gas detection The sensor control unit 16 that detects fuel leakage or incomplete combustion based on the resistance change of the body 1 is 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 includes a drive circuit 19, an A / D conversion circuit 20, a signal processing circuit 21, a temperature signal conversion circuit 22, an output circuit 23, a memory 24, and the like.
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 the main control unit 42 when the signal processing circuit 21 determines that the fuel leakage is detected, and outputs an incomplete combustion detection signal when the signal processing circuit 21 determines that incomplete combustion is detected. Output to the main control unit 42.

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 setting time T2 has elapsed after the blower 47 is activated, the igniter 50 is activated and the on-off valve 53 and the proportional valve 54 are opened (corresponding to switching to the fuel supply state). The ignition process for igniting 41 is executed, and the operation of the igniter 50 is stopped when the forced spark set time T3 elapses after the output voltage of the thermocouple 51 reaches the ignition detection level and the ignition of the burner 41 is detected. Has been.
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 illustration is omitted, the main control unit 42 determines the failure of the thermocouple 51 based on the output voltage of the thermocouple 51 from the time when the operation start is instructed by the operation switch 55 until the set time T1 for waiting for airflow elapses. The thermocouple failure determination process is performed.

  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, the sensor control unit 16 executes the pre-ignition detection mode during the first half of ignition from when the operation start is commanded by the operation switch 55 until the main control unit 42 executes the ignition process. Then, 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 is instructed by the operation switch 55.
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 pre-ignition detection mode will be described.
In the present invention, the sensor control unit 16 causes the gas detector 1 to be in a high-temperature operation state during the first half of ignition from when the operation start is commanded by the operation switch 55 until the main control unit 42 executes the ignition process. It is configured to execute a pre-ignition detection mode in which the operation of the heater 2 is controlled and the combustible gas is detected based on the electrical characteristics of the gas detector 1 and fuel leakage is detected based on the detection information.
In this embodiment, the sensor control unit 16 is configured to execute a fuel leak detection process for detecting a fuel leak based on detection information of combustible gas a plurality of times in the pre-ignition detection mode.

As shown in FIG. 5, in this embodiment, the length of the pre-ignition period is the sum of the air blow standby setting time T1 and the pre-purge setting time T2, that is, a time in the range of 4 to 7 seconds. Is set to
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.
Further, as shown in FIG. 6, when the high-temperature side sensitive temperature is set to 400 ° C., the temperature of the gas detector 1 is about 1 second after the energization of the heater 2 is started and the high temperature operation state is started. Rises to the high temperature sensitive temperature. Therefore, in the pre-ignition detection mode, the timing of the fuel leak detection process is set one second after the start of the high-temperature operation state, and further, the fuel leak detection process timing is set every one second thereafter. The process is configured to be executed a plurality of times (in this embodiment, four 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.

Next, the initial detection mode will be described.
In the initial detection mode, the sensor control unit 16 increases the frequency of the high-temperature operation state during the comparison setting time T7 set to be equal to or less than the initial detection setting time T6, as compared with the normal detection mode. 1. Based on the electrical characteristics of 1, detect flammable gas in the high temperature operation state, detect the fuel leakage by the detection information, and detect the incomplete combustion gas in the low temperature operation state, detect the incomplete combustion by the detection information Therefore, the operation of the heater 2 is controlled so that the gas detector 1 is alternately and repeatedly switched between a high temperature operation state and a low temperature operation state.

  In this embodiment, the sensor control unit 16 normally detects the frequency of setting the high temperature operation state in the comparative set time T7 by making the time for setting the low temperature operation state shorter in the initial detection mode than in the normal detection mode. It is configured to be more than the mode.

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 this embodiment, the number of times that the sensor control unit 16 executes the process of detecting the combustible gas in one high temperature operation state in the initial detection mode is set to be combustible in one high temperature operation state in the normal detection mode. The number of times of executing the process of detecting the gas is increased.
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, and when the high temperature side sensitive temperature is set to 400 ° C. as shown in FIG. After the energization to 2 is started and the high temperature operation state is started, the temperature of the gas detector 1 rises to the high temperature side sensitive temperature in about 1 second.
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 one high temperature operation state is set to 4 times, for example. ing.
That is, the number of times of the fuel leak detection process in one 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.

  By configuring the sensor control unit 16 to sequentially execute the pre-ignition detection mode, the initial detection mode, and the normal detection mode as described above, the sensor control unit 16 is configured to perform the gas detector 1 during the pre-ignition period. The fuel leakage detection process is executed by controlling the operation of the heater 2 so as to bring the gas to a high temperature operation state, and after the ignition process is started, the gas detector 1 is repeatedly switched between a high temperature operation state and a low temperature operation state. Further, the operation of the heater 2 is controlled so that the fuel leakage process is executed in the high temperature operation state based on the electrical characteristics of the gas detector 1 and the incomplete combustion detection process is executed in the low temperature operation state. It will be.

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.

When the fuel leakage detection signal is transmitted from the sensor control unit 16 during the first half of ignition from the start of operation to the execution of the ignition process, the main control unit 42 does not execute the ignition process, 56 is lit.
Further, when a fuel leakage detection signal is transmitted from the sensor control unit 16 after the ignition process is started, the main control unit 42 closes the on-off valve 53 and the proportional valve 54 (corresponding to switching to the fuel supply stop state). After the fire extinguishing process is performed and the alarm lamp 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.
That is, as shown in FIG. 1, the control means C is configured by the sensor control unit 16 and the main control part 42, and the control means C is based on the electrical characteristics of the gas detector 1 after the ignition process is started. When the fuel leak detection process for detecting the fuel leak is executed and the fuel leak is detected in the fuel leak detection process, the fuel intermittent means V is switched to the fuel supply stop state.

[Another embodiment]
Next, another embodiment will be described.
(A) In the above embodiment, the case where the pre-ignition detection mode is executed in the pre-ignition period from when the combustion start command is issued until the ignition process is executed is illustrated, but even after the ignition process is started, The pre-ignition detection mode may be continued until the ignition of the burner 41 is detected based on the output voltage of the thermocouple 51.

(B) In the above embodiment, the case where the initial detection mode is configured to be executed during the initial detection set time T6 after the start of the ignition process is illustrated, but the initial detection mode is omitted, The normal detection mode may be executed immediately after the ignition process is started.

(C) When the control means C is configured to execute the combustion leak detection process a plurality of times during the first half of ignition, the number of times is not limited to the number illustrated in the above embodiment.
Further, the control means C may be configured so that the combustion leakage detection process is executed once during the first half of ignition.

(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 above embodiment, and the fuel leak detection process is configured to be executed continuously. May be.

(E) The length of the pre-ignition period from when the start of combustion is commanded to when the ignition process is executed is not limited to the time in the range of 4 to 7 seconds exemplified in the above embodiment, but the range It is possible to set a time longer or shorter than this time.

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

(G) In the above embodiment, the gas detector 1 is exemplified for the case where the gas detector 1 is capable of detecting combustible gas in a high temperature operation state and detecting incomplete combustion gas in a low temperature operation state. A gas detector for detecting incomplete combustion gas may be separately provided by using one that detects only combustible gas.

(H) In the above embodiment, the case where the present invention is applied to a combustion apparatus that uses gas fuel as fuel is illustrated, but the present invention can also be applied to a combustion apparatus that uses liquid fuel as fuel, In this case, the gas detector 1 detects the gas obtained by vaporizing the liquid fuel as a combustible gas.
Further, when the present invention is applied to 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.

(I) In the above embodiment, the case where the control means C is configured by the sensor control unit 16 and the main control unit 42 which are separate from each other has been illustrated, but the control means C is a single unit using a microcomputer. It may be configured.

(Nu) In addition to the gas fan heater exemplified in the above embodiment, the present invention can be applied to 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 combustion apparatus that can further improve the safety of ignition of the burner.

Block diagram of combustion equipment The figure which shows the principal part of a gas sensor Gas sensor partially cutaway external view Diagram showing equivalent circuit of gas sensor The figure which shows the time chart of the control action of the combustion device The figure which shows the time chart of control operation of a gas detection part 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 Longitudinal right side view showing the schematic configuration of the combustion device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas detection body 2 Heating means 41 Burner 44 Intake port 45 Outlet port 46 Casing 47 Blowing means 50 Ignition means C Control means V Fuel interruption means

Claims (5)

A burner for burning the supplied fuel;
A fuel intermittent means capable of switching between a fuel supply state for supplying fuel to the burner and a fuel supply stop state for stopping the supply of fuel to the burner;
A gas detector whose electrical characteristics change in response to fuel;
A control means for performing an ignition process for operating the ignition means for igniting the burner and switching the fuel intermittent means to the fuel supply state when the start of combustion of the burner is commanded,
When the control means executes a fuel leak detection process for detecting a fuel leak based on an electrical characteristic of the gas detector after the ignition process is started, and detects the fuel leak in the fuel leak detection process. A combustion apparatus configured to switch the fuel interrupting means to the fuel supply stop state,
The control means is configured to execute the fuel leak detection process during the first half of the ignition period from when the start of combustion is commanded to when the ignition process is executed,
The control means is configured to execute the fuel leak detection process a plurality of times during the first ignition phase,
When the control means detects a fuel leak in the pre-ignition period, it is configured not to execute the ignition process,
The gas detector is sensitive to the fuel in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature, and the electrical characteristics change, and the incomplete combustion gas is in a low temperature operating state where the temperature is lower than the high temperature side sensitive temperature. Is configured to change the electrical characteristics in response to
A heating means for heating the gas detector is provided,
In the pre-ignition period, the control means controls the operation of the heating means to bring the gas detector into the high-temperature operation state, and executes the fuel leak detection process. After the ignition process is started, The operation of the heating means is controlled so that the gas detector is alternately and repeatedly switched between the high temperature operation state and the low temperature operation state, and the fuel is detected in the high temperature operation state based on electrical characteristics of the gas detector. It is configured to execute an incomplete combustion detection process that performs a leakage process and detects incomplete combustion in the low temperature operation state,
The high-temperature operation at the comparison setting time that is set to be equal to or less than the initial detection set time after the initial detection set time has elapsed during the initial detection set time after the ignition process is started. A combustion apparatus configured to control the operation of the heating means so as to alternately and repeatedly switch the gas detector between the high temperature operation state and the low temperature operation state in a state where the frequency of the state is increased. A burner for burning the supplied fuel;
A fuel intermittent means capable of switching between a fuel supply state for supplying fuel to the burner and a fuel supply stop state for stopping the supply of fuel to the burner;
A gas detector whose electrical characteristics change in response to fuel;
A control means for performing an ignition process for operating the ignition means for igniting the burner and switching the fuel intermittent means to the fuel supply state when the start of combustion of the burner is commanded,
When the control means executes a fuel leak detection process for detecting a fuel leak based on an electrical characteristic of the gas detector after the ignition process is started, and detects the fuel leak in the fuel leak detection process. A combustion apparatus configured to switch the fuel interrupting means to the fuel supply stop state,
The control means is configured to execute the fuel leak detection process during the first half of the ignition period from when the start of combustion is commanded to when the ignition process is executed ,
The gas detector is sensitive to the fuel in a high temperature operating state where the temperature is equal to or higher than the high temperature side sensitive temperature, and the electrical characteristics change, and the incomplete combustion gas is in a low temperature operating state where the temperature is lower than the high temperature side sensitive temperature. Is configured to change the electrical characteristics in response to
A heating means for heating the gas detector is provided,
In the pre-ignition period, the control means controls the operation of the heating means to bring the gas detector into the high-temperature operation state, and executes the fuel leak detection process. After the ignition process is started, The operation of the heating means is controlled so that the gas detector is alternately and repeatedly switched between the high temperature operation state and the low temperature operation state, and the fuel is detected in the high temperature operation state based on electrical characteristics of the gas detector. It is configured to execute an incomplete combustion detection process that performs a leakage process and detects incomplete combustion in the low temperature operation state,
The high-temperature operation at the comparison setting time that is set to be equal to or less than the initial detection set time after the initial detection set time has elapsed during the initial detection set time after the ignition process is started. A combustion apparatus configured to control the operation of the heating means so as to alternately and repeatedly switch the gas detector between the high temperature operation state and the low temperature operation state in a state where the frequency of the state is increased.   The combustion apparatus according to claim 2, wherein the control means is configured to execute the fuel leak detection process a plurality of times during the first ignition phase. The combustion apparatus according to claim 2 or 3 , wherein the controller is configured not to execute the ignition process when a fuel leak is detected in the pre-ignition period. Air outside the casing sucked through an intake port provided in a casing that houses the burner is supplied to the burner as combustion air, and combustion gas of the burner is discharged from a blowout port provided in the casing to the outside of the casing. Blowing means that ventilate so as to blow out is provided,
The combustion apparatus according to any one of claims 1 to 4 , wherein the gas detector is provided in the intake port or in the vicinity of the intake port so as to be sensitive to fuel in the air sucked through the intake port.

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