JPH11182840A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion device to stop combustion of a burner through detection of insufficient ventilation of a room interior without increasing 7(. cost and even before the generation of CO. SOLUTION: In a combustion device, a burner 2 and a fan 6 to feed combustion air to the burner 2 are contained in a casing C, a suction port 7a to suck combustion air in the casing C and an exhaust port 7b to discharge exhaust gas after combustion by the burner 2 are provided, a temperature detecting means 9 is provided to detect the temperature of combustion air fed to the burner 2, and a control means H is provided to effect control so that combustion of the burner 2 is stopped when a deviation between a lowest detecting temperature detected by the temperature detecting means 9 and a highest detecting temperature is increased to a value exceeding a given value, combustion of the burner 2 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner and a fan for supplying combustion air to the burner, which are housed in a casing, and an intake port for sucking the combustion air into the casing and a burner after combustion by the burner. The present invention relates to a combustion device provided with an exhaust port for discharging exhaust gas.

[0002]

2. Description of the Related Art The above-described combustion apparatus is applied to, for example, a hot water supply apparatus, and is often installed in a room such as a hangar. In such a case, if ventilation of the room is not sufficient, an exhaust port is provided. The interior of the room may be polluted by exhaust gas discharged from the burner, or the exhaust gas may be sucked directly from the intake port. Therefore, conventionally, a CO sensor is located in the passage of the combustion air sucked from the intake port, and a part of the exhaust gas after combustion is mixed with the combustion air and included in the combustion air after the mixing. C
There is a known configuration in which the O concentration is detected, and when the O concentration is equal to or higher than a predetermined value, the ventilation of the room is not sufficient, and it is determined that the room is contaminated with CO, and the combustion of the burner is stopped. (For example, JP-A-6-229538).

[0003]

However, in the method of determining the contamination state of the combustion air using a CO sensor, the contamination is detected after CO is actually generated and the CO concentration reaches a certain value. Therefore, the detection timing is inevitably delayed, which is not always satisfactory. In other words, when the ventilation of the room is not sufficient, the oxygen concentration in the room decreases with the combustion of the burner, but at that time, the concentration of CO contained in the combustion air is not necessarily
The concentration does not always reach the concentration that can be detected by the CO sensor, and therefore, there is a possibility that a timing delay may occur in the contamination detection. Further, as a CO sensor, a catalytic combustion type CO sensor is frequently used, but it is quite expensive. Also, a semiconductor type CO sensor is cheaper than the catalytic combustion type, but still expensive. Therefore, there is also a disadvantage that the cost of the combustion device is increased.

[0004] The present invention has been made in view of the above point, and its object is to provide sufficient ventilation without incurring an increase in cost, and even before CO is actually generated, around a device such as a room. To provide a combustion device capable of detecting combustion and stopping combustion of the burner.

[0005]

To achieve this object, according to the first aspect of the present invention, a casing containing a burner and a fan for supplying combustion air to the burner is provided in a casing. In a combustion device provided with an intake port for sucking air and an exhaust port for discharging exhaust gas after combustion, a temperature detecting means for detecting a temperature of combustion air supplied to a burner is provided, and a combustion operation of the burner is performed. After the start, when the deviation between the minimum detection temperature and the maximum detection temperature detected by the temperature detection means is equal to or more than a predetermined value, control means for controlling the combustion of the burner to be stopped is provided. Even if CO is not generated, or even in a state where the CO concentration is low, it is possible to detect insufficient ventilation around the device and stop the combustion of the burner.

That is, when the ventilation is not sufficient and the exhaust gas from the exhaust port is again in an exhaust gas recirculation state where it is sucked from the intake port, the temperature of the sucked combustion air rises. Since the ventilation state, in other words, the contamination of the combustion air is determined based on the temperature rise, even if the CO is not actually generated or the CO concentration is low, the contamination of the combustion air is surely prevented. The detection can stop the combustion of the burner, and it is possible to prevent the combustion failure of the burner from occurring. In such a case, if the temperature detected by the temperature detecting means simply exceeds a certain value, it is determined that the combustion air is contaminated, so that the ambient temperature in the vicinity of the device becomes extremely higher than the surrounding temperature. If high,
Even if it is not in the exhaust gas recirculation state, the detected temperature may be higher than a certain value.On the contrary, if it is extremely low, the detected temperature may not be higher than the certain value even in the exhaust gas recirculation state. It may cause malfunction. However, by determining the ventilation state based on the difference between the minimum detection temperature and the maximum detection temperature, the determination is made in consideration of not only the ambient temperature around the device but also the ambient temperature around the device. The contamination of the combustion air can be reliably detected without the malfunction as described above. Further, as a detecting means therefor, a temperature detecting means such as a thermistor is sufficient, so that the cost is lower than that of a conventional CO sensor, and the cost of the apparatus can be reduced.

According to the second aspect of the present invention, the fan is provided between the intake port and the burner, and the temperature detecting means is provided between the intake port and the fan. Of course, the temperature of the combustion air sucked from the intake port can be reliably detected by the temperature detecting means, and the effect of heat by the combustion of the burner on the temperature detecting means is reduced by the fan interposed between the burner and the temperature detecting means. Thus, the temperature of the combustion air can be detected more accurately.

According to the third aspect of the present invention, since the temperature detecting means is provided near the intake port,
Within the range where the temperature of the combustion air can be detected, it is located as far away from the burner as possible, minimizing the thermal effect of burning the burner and detecting the temperature of the combustion air more accurately. it can.

According to the fourth aspect of the present invention, since the temperature detecting means is provided on a substrate constituting the control means, it is usually provided on a substrate located at a position distant from the burner. The thermal effect of the burner combustion is small, and the temperature of the combustion air can be accurately detected.
In addition, the connection of the temperature detecting means to the substrate becomes easy. In particular, when the temperature detecting means and the substrate on which the temperature detecting means are provided between the intake port and the fan as described above, a cooling effect of the substrate due to the flow of combustion air can be expected, and the temperature detection means can be provided. By locating the means near the intake port, more accurate temperature detection becomes possible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which a combustion device according to the present invention is applied to a hot water supply device will be described with reference to the drawings. As shown in FIG. 1, the hot water supply apparatus includes a hot water supply unit K for heating water to supply hot water, a control unit H serving as control means for controlling the operation of the hot water supply unit K, and instructing the control unit H with operation information and the like. The hot water supply unit K and the control unit H are housed in a casing C.

The hot water supply unit K determines whether or not a gas combustion type burner 2, a heat exchanger 3 heated by the burner 2, an igniter 4 for igniting the burner 2, and a burner 2 are ignited in the combustion chamber 1. A frame rod 5 and the like to be detected are provided. Further, a fan 6 is provided that allows the combustion air to flow through the burner 2 and that allows the ventilation amount to be changed and adjusted.

When the fan 6 starts operating, outside air of the apparatus is sucked from an intake port 7a provided below the front surface of the casing C to a suction port 6a of the fan 6 through an air supply passage 8, and the fan 6 The combustion air is supplied to the casing 2, and the exhaust gas after combustion is discharged to the outside of the apparatus through an exhaust port 7 b provided at the upper front of the casing C.
A substrate Ha constituting a control unit H described later is provided near the intake port 7a in the air supply passage 8, and a combustion air temperature thermistor 9 as temperature detecting means is provided on the substrate Ha. The combustion air temperature thermistor 9 is disposed so as to be located near the intake port 7a.

The heat exchanger 3 is connected to a water inlet 10 for supplying water and a hot water outlet 11 for discharging hot water to a hot water tap (not shown). The water inlet channel 10 is provided with a water flow rate sensor 12 for detecting a water flow rate to the heat exchanger 3 and an incoming water temperature thermistor 13 for detecting an incoming water temperature, respectively.
The tapping path 11 is provided with a tapping temperature thermistor 14 for detecting tapping temperature. Further, an electromagnetically operated on-off valve 16 and an electromagnetically operated gas proportional valve 17 capable of changing and adjusting the fuel supply amount are provided in the fuel supply passage 15 for the burner 2. Thermistor 1
3. Hot water temperature thermistor 14, on-off valve 16, gas proportional valve 1
7 are all stored in the casing C.

The remote control operation unit R is communicably connected to the control unit H. The operation switch 18 instructs the control unit H to start and stop the hot water supply operation, and the temperature setting switch for setting the target hot water supply temperature. 19, a display unit 20 for displaying hot water supply temperature, etc., a notification lamp 21, a notification buzzer 22, and the like.

The control unit H is provided with a microcomputer, and performs a normal combustion control means 100 for executing a normal combustion control during hot water supply, an exhaust gas recirculation for detecting an exhaust gas recirculation state and stopping the combustion of the burner 2. The detection means 101 and the like are provided in the form of a control program.

The normal combustion control means 100 includes a hot water supply section K
In the state where is set to the operating state, the combustion of the burner 2 is started with the passage of water to the heat exchanger 3 and the passage of water to the heat exchanger 3 is stopped. In addition to controlling the combustion of the burner 2 to stop, when the flow of water to the heat exchanger 3 is detected, the amount of combustion of the burner 2 is adjusted so that the hot water temperature reaches the target hot water supply temperature. It is configured to execute normal combustion control for controlling the number of revolutions of the fan 6 such that a proper amount of combustion air flows with respect to the combustion amount.

Specifically, after the operation state is set by turning on the operation switch 18 and the water flow rate detected by the water flow rate sensor 12 with the opening operation of the hot water tap exceeds the set water flow rate, the fan 6 starts ventilation operation, and
The on / off valve 16 is opened to adjust the valve so that the gas proportional valve 17 has the ignition gas amount, and the igniter 4 ignites the burner 2 and detects whether the flame rod 5 has ignited. And the incoming water temperature thermistor 1
3. A burner necessary for setting the hot water supply temperature to the target temperature based on the detection information of each of the tap water temperature thermistor 14 and the water flow rate sensor 12 and the information of the target hot water supply temperature set by the temperature setting switch 19. The combustion amount of No. 2 is calculated. Then, while adjusting and controlling the gas proportional valve 17 so that the gas amount corresponds to the obtained combustion amount,
The ventilation amount of the fan 6 is adjusted and controlled so that the ventilation amount of the fan 6 becomes an appropriate combustion state with respect to the regulated gas amount, and hot water at a target temperature is supplied from the hot water tap.

The exhaust gas recirculation detecting means 101 detects the lowest temperature detected by the combustion air temperature thermistor 9 after the combustion operation of the burner 2 is started, and detects the detected temperature of the combustion air temperature thermistor 9 thereafter. When the difference between the detected temperature and the minimum detected temperature is equal to or higher than the maximum detected temperature at which a predetermined value is obtained, the exhaust gas discharged from the exhaust port 7b is again sucked into the casing C from the intake port 7a, and the exhaust gas supplied to the burner 2 is returned. It is configured to stop the combustion of the burner 2 assuming the circulation state. Specifically, if the detected temperature of the combustion air temperature thermistor 9 intermittently detected is lower than the previous detected temperature, the detected temperature is updated and stored as the minimum detected temperature Ts. Then, after detecting the minimum detection temperature Ts, the maximum detection temperature T at which the deviation between the detection temperature of the combustion air temperature thermistor 9 and the minimum detection temperature Ts is equal to or more than a predetermined value.
When k is detected, the on-off valve 16 and the gas proportional valve 17 are closed to stop the combustion of the burner 2 and stop the operation of the fan 6.

As shown in FIG. 2, the above-described hot water supply device S is often installed in a hangar L outside the room,
Under such an installation condition, the exhaust gas from the exhaust port 7b provided in the casing C of the hot water supply device is
The inside of the casing C may be filled and sucked again from the intake port 7a of the casing C, which is particularly effective in such an installation situation.

In the case where the hot water supply apparatus is installed as described above, when the normal combustion control is started and the fan 6 is operated, the air in the hangar L is initially sucked and the hangar L
If the ventilation is sufficient, then the air outside the hangar L is gradually sucked, and the temperature detected by the combustion air temperature thermistor 9 is, as shown in FIG. The temperature drops from the ambient temperature R1 to the outside temperature R2 outside the hangar L. That is, when the outside air temperature R2 is set as the minimum detection temperature Ts, when the deviation from the minimum detection temperature Ts reaches the maximum detection temperature Tk at which the deviation is equal to or more than the predetermined value, the combustion of the burner 2 is stopped.

As described above, by using the minimum temperature Ts detected by the combustion air temperature thermistor 9 as a reference, even when the ambient temperature R1 inside the hangar L is higher than the outside air temperature R2 outside the hangar L, it can be controlled. The exhaust gas recirculation state can be reliably detected without being affected by the high ambient temperature R1 in the hangar L. That is, when the exhaust gas recirculation state is to be detected based on the detected temperature at the beginning of the operation of the fan 6, if the ambient temperature R1 in the hangar L is high due to, for example, the influence of the West Sun, the detected temperature at the beginning of the operation is At the point in time when the temperature becomes higher than the predetermined value, the exhaust gas recirculation state may have already passed, and further time may have passed. However, such a disadvantage is solved by using the minimum detected temperature Ts as a reference.

The temperature change shown in FIG. 3A shows a case where the ambient temperature R1 inside the hangar L is higher than the outside air temperature R2 outside the hangar.
When 1 and the outside air temperature R2 outside the hangar are the same, the temperature changes as shown in FIG. 3B. That is, the hangar L
When the ambient temperature R1 in the inside and the outside air temperature R2 outside the hangar are the same, when the fan 6 is operated at the start of the normal combustion control, the detected temperature of the combustion air temperature thermistor 9 at the beginning of the operation of the fan 6 becomes the lowest. It is stored as the detected temperature Ts, and thereafter, when the detected temperature rises by a predetermined value or more and reaches the maximum detected temperature Tk, the combustion of the burner 2 is stopped.

The control operation of the control section H will be described with reference to a control flowchart shown in FIG. After the operation switch 18 is turned on, when the detection value of the water flow rate sensor 12 exceeds the set water quantity as the hot water tap is opened, water flow to the heat exchanger 3 is detected (steps 1 and 2). 2), the normal combustion control is executed assuming that the burner 2 has been instructed to start the combustion operation. In other words, the fan 6 is operated to perform pre-purge, and the burner 2 is ignited so that the tapping temperature detected by the tapping temperature thermistor 14 becomes the target hot water supply temperature set by the temperature setting switch 19.
The amount of fuel supplied to the fan and the amount of ventilation of the fan 6 are controlled (steps 3 and 4).

Such control is executed until a hot water tap (not shown) is closed and no water flow is detected or the operation switch 18 is turned off (step 7, step 7).
8). In other words, when the normal combustion control is being executed,
When the hot water tap is closed and the detection value of the water flow rate sensor 12 falls below the set water amount, the on-off valve 16 and the gas proportional valve 27 are closed,
The operation of the fan 6 is stopped to stop the combustion of the burner 2, and even when the hot water tap is not closed, if the operation switch 18 is turned off, the combustion of the burner 2 is stopped (step 9).

During the normal combustion control as described above, the temperature detection by the combustion air temperature thermistor 9 is started simultaneously with the start of the pre-purge by the fan 6, and the minimum detected temperature Ts is stored as described above. When the difference between Ts and the subsequent detected temperature Tk of the combustion air temperature thermistor 9 is equal to or higher than the maximum detected temperature Tk at which the predetermined value is reached, the notification lamp 21 is turned on and the notification busser 22 is operated until a certain time has elapsed. The notification is activated. And on-off valve 1
6 and the gas proportional valve 27 are closed to stop the combustion of the burner 2 and stop the operation of the fan 6 (steps 5, 6, and 7).
9).

In this way, the exhaust gas is again supplied to the burner 2.
By detecting the temperature rise of the combustion air due to the exhaust gas recirculation supplied to the burner 2 in a state where the combustion of the burner 2 is not affected as much as possible, an exhaust gas recirculation state, that is, insufficient ventilation is detected, and the burner 2 is detected. Combustion can be stopped.

[Other Embodiments] (1) In the above embodiment, the fan 6 is provided on the upper side of the burner 2 in the ventilation direction of the combustion air, and the fan 6 is pushed into the ventilation type. A fan 6 may be provided on the side to form a suction ventilation type. In the case of a push-in ventilation type, the combustion air temperature thermistor 9 is used.
Is provided in the vicinity of the intake port 7a provided in the casing C, but may be provided in the air supply path 8 leading to the fan 6, for example, in the intake port 6a of the fan 6. Further, an example is shown in which the substrate Ha of the control unit H is located in the air supply passage 8 and the combustion air temperature thermistor 9 is provided on the substrate Ha. However, regardless of the substrate Ha, the combustion air temperature thermistor 9 is provided. It is also possible to provide only the inside of the air supply passage 8.

(2) In the above-described embodiment, the configuration has been described in which the temperature detection by the combustion air temperature thermistor 9 is started simultaneously with the start of the pre-purge by the fan 6, but the temperature is started from the time when the combustion of the burner 2 is actually started. It may be configured to start detection. Further, the temperature detection by the combustion air temperature thermistor 9 does not necessarily need to be performed continuously, but may be performed intermittently at regular intervals.

(3) In the above embodiment, an example is shown in which the present invention is applied to a hot water supply apparatus. However, the present invention is not limited to the hot water supply apparatus.
It is also possible to apply to a heating device equipped with a combustion device.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of a water heater.

FIG. 2 is an installation diagram of a water heater.

FIG. 3 is a graph showing a change in detected temperature of a combustion air temperature thermistor;

FIG. 4 is a flowchart showing a control operation.

[Explanation of symbols]

 2 Burner 6 Fan 7a Intake port 7b Exhaust port 9 Temperature detecting means C Casing H Control means Ha substrate

Claims (4)

[Claims] 1. A burner and a fan for supplying combustion air to the burner are housed in a casing, and an intake port for sucking the combustion air into the casing and exhaust gas for discharging exhaust gas after combustion by the burner. A combustion device provided with a port, provided with temperature detection means for detecting the temperature of the combustion air supplied to the burner, and a minimum temperature detected by the temperature detection means after the start of the combustion operation of the burner. A combustion device provided with control means for controlling so as to stop the combustion of the burner when the deviation between the detected temperature and the maximum detected temperature is equal to or more than a predetermined value. 2. The combustion device according to claim 1, wherein the fan is provided between the intake port and the burner, and the temperature detecting means is provided between the intake port and the fan. . 3. The combustion device according to claim 1, wherein the temperature detecting means is provided near the intake port. 4. The apparatus according to claim 1, wherein said temperature detecting means is provided on a substrate constituting said control means.
Item 13. The combustion device according to Item.