JP4048929B2 - Gas hot air heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to ignition control of a gas hot air heater.
[0002]
[Prior art]
Conventionally, this type of gas hot air heater has a combustion chamber with a burner, ignition means, and a flame sensor composed of a thermocouple in an outer case having an air inlet and a hot air outlet, and an air inlet. Air supply means for supplying the sucked air to the burner and discharging air heated in the combustion chamber from the hot air outlet, gas supply means for supplying gas to the burner from the gas connection port provided in the outer case, and equipment The control means which controls operation | movement of is provided.
[0003]
When there is an instruction for heating operation, the control means operates the air blowing means to circulate the air in the combustion chamber and purifies the air in the combustion chamber. This is generally called a pre-purge operation. After that, when the ignition means is operated, the gas supply means is operated, and when gas is supplied from the gas connection port to the burner in the combustion chamber, the discharge spark of the ignition means ignites the gas to form a flame, and the thermoelectric An electromotive force is generated when the pair is burned. The control means detects the electromotive force, determines that the burner has ignited, and stops the ignition means.
[0004]
Thereafter, the control means detects the room temperature and continues the heating operation while adjusting the combustion amount so that the room temperature becomes the set temperature. One of the features of the gas hot air heater is that the vaporized fuel is directly supplied, so that it takes a short time from the operation instruction until the hot air blows out.
[0005]
In order to make it more prominent, there is a tendency to promptly detect the detection of the flame at the time of ignition, appeal the user to make the operation of the ignition means shorter and to ignite quickly. Specifically, ignition is determined by setting an ignition detection threshold value for determining an electromotive force of a thermocouple to a low value or detecting a slight increase in electromotive force.
[0006]
On the other hand, the gas supply to the gas hot air heater is performed by connecting a gas stopper provided indoors and a gas connection port of the device with a rubber hose. In general, for safety reasons, a hose dedicated to gas equipment that has a gas shut-off mechanism at the end of the hose on the equipment side and a locking mechanism that prevents the disconnection at both ends (hereinafter referred to as a gas hose for convenience) Is used. The device side of the gas hose functions to open the gas shut-off mechanism when the gas connection port is connected and allow the gas to flow. When the gas hose is not connected to the gas hose, it closes and shuts off the gas.
[0007]
Gas plug side is connected, it is open regardless of not being. In addition, users of gas hot air heaters may use the device after using the device, after closing the gas plug and removing the gas cord from the gas plug, because they are concerned about gas leakage.
[0008]
[Problems to be solved by the invention]
However, after using the equipment, if the gas hose is disconnected from the gas plug before going to bed and connected again in the next morning, the gas hose is disconnected from the gas plug for several hours and the end on the gas plug side is left open. The Then, the gas remaining in the gas hose after using the device gradually diffuses into the air from the open side of the gas hose, and the inside of the hose is replaced with air. The gas stopper side is easily replaced with air, but the gas remains on the equipment side, and the gas concentration inside the gas hose is shaded. When this is connected to a gas plug, an air pool is created near the gas plug, creating a sandwich-like situation in which air is sandwiched between fuel gases.
[0009]
When the appliance is instructed to perform heating operation in the above state, the ignition is detected by the gas near the appliance side in the gas supply passage in the appliance or in the gas hose, and then the burner is still in an unstable state of the flame. Since the air is supplied to the flame, the flame will blow out and the burner will misfire. After the supply of fuel gas is temporarily cut off by air, gas is supplied from the gas plug, but since the ignition has already been detected and the ignition means has stopped, the burner remains misfired and the equipment stops abnormally. There was a problem of ending up.
[0010]
The present invention solves the above-described conventional problems, and even if air accumulation occurs in the middle of the gas supply path to the equipment (in the gas hose), the ignition failure is achieved by reliably igniting and continuing combustion stably. The object is to provide a gas hot-air heater with reduced air consumption and improved usability.
[0011]
[Means for Solving the Problems]
In order to solve the above-described conventional problems, the gas warm air heater of the present invention performs an ignition operation and detects ignition, and then forcibly sets the maximum combustion amount for a predetermined time. The ignition operation is configured to be repeated , and during that time, the gas is equal to the capacity of a gas hose that is connected to the gas connection port and supplies fuel to the equipment, and is longer than the time required for supplying the burner .
[0012]
Even if the flame of the burner is misfired due to air accumulation in the gas hose after the ignition determination, the ignition operation is performed again within a predetermined time, and if the fuel gas is supplied again after the air has passed, the burner is ignited again and burns. Will continue. Moreover, since all the gas capacities in the gas hose pass through the burner while it is determined to perform reignition due to misfire, it is possible to reliably detect misfire due to air accumulation in the gas hose.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, a combustion chamber having a burner, an ignition means and a flame sensor faced in an outer case having an air inlet and a hot air outlet, and air sucked from the air inlet is supplied to the burner. And blowing means for discharging the air heated in the combustion chamber from the hot air outlet, gas supply means for supplying gas to the burner from the gas connection port provided in the outer case, and control means for controlling the operation of the device comprising a control means, during the first timer period from after the ignition detection performed an ignition operation to forcibly maximum combustion amount, upon detecting a misfire in the first timer period configured to repeat the ignition operation again The first timer time is longer than the time required for supplying a gas equal to the capacity of the gas hose connected to the gas connection port and supplying fuel to the equipment to the burner . In the predetermined time after the ignition determination, even if the flame of the burner is misfired due to air accumulation in the gas hose, the ignition operation is performed again from the beginning. Is supplied, the burner is ignited again and combustion continues.
[0014]
Therefore, even in an unstable fuel gas supply state in which the gas hose is replaced with air, good ignition can be performed, combustion can be continued, and usability can be improved.
[0015]
In addition, the maximum combustion occurs within a predetermined time, and the amount of gas passing through the burner and the amount detected by the flame sensor increase, so that air accumulation in the gas hose can be detected quickly and accurately.
[0016]
Moreover, since all the gas capacities in the gas hose pass through the burner while it is determined to perform reignition due to misfire, it is possible to reliably detect misfire due to air accumulation in the gas hose.
[0017]
According to the second aspect of the present invention, the ignition operation is repeated once. And while misfire due to air accumulation can be reliably detected, unnecessary repetition of ignition operation can be prevented.
[0018]
According to a third aspect of the present invention, misfire is determined when the detection value of the flame sensor is decreased by the first detection threshold during the first timer period.
[0019]
And while the electromotive force stably increases at maximum combustion, misfire is detected because the electromotive force has changed in the decreasing direction, so it is possible to quickly determine misfire, and the outflow of unburned gas supplied after the air pool The gas odor at the time of ignition can be suppressed.
[0020]
According to a fourth aspect of the present invention, misfire is determined even when the detection value of the flame sensor falls below a second detection threshold value for determining ignition detection. Since misfire is determined even if the electromotive force falls below the ignition detection threshold, misfire that occurs immediately after detection of ignition can be detected more quickly.
[0021]
According to the fifth aspect of the present invention, the control means is such that the blowing time performed before the ignition means is activated is longer in the reignition operation than in the first ignition operation.
[0022]
The gas components, lean gas, and unburned gas generated by the combustion remaining in the combustion chamber are discharged over a longer time than the first ignition, so that the combustion chamber can be sufficiently cleaned and a stable reignition operation is performed. be able to.
[0023]
The invention according to claim 6 is such that the operation time of the ignition means is longer in the reignition operation than in the initial ignition operation.
[0024]
By securing a sufficient ignition time at the time of reignition, a stable reignition operation can be performed reliably even when fuel gas having an unstable gas concentration mixed with air is supplied.
[0025]
According to the seventh aspect of the present invention, the contents displayed by the control means are different between the initial ignition operation and the reignition operation.
[0026]
Then, the user's discomfort and distrust can be alleviated by notifying the user of the operation of the device that varies depending on the state of the supplied fuel gas by display.
[0027]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0028]
FIG. 1 is a configuration diagram showing a schematic configuration of a gas hot air heater in an embodiment of the present invention. Reference numeral 1 denotes an exterior case, and the top plate 2 and the bottom plate 3 constitute an exterior of the device. The outer case 1 has an air inlet 4 at a position corresponding to the upper back of the device, and a hot air outlet 5 at a position corresponding to the lower front, and an air filter 6 is attached to the air inlet 4. 7 is a combustion chamber provided in the upper part of the outer case 1, 8 is a burner provided in the combustion chamber 7, 9 is an ignition means, 10 is a flame sensor composed of a thermocouple arranged near the flame of the burner 8, and 11 is A blower fan comprising a cross flow fan provided at the lower part of the combustion chamber 7, 12 a motor for driving the blower fan 11, 13 a cover plate covering the upper surface and the front surface of the combustion chamber 7, and 14 hot air from the blower fan 11 This is a fan case that leads to the hot air outlet. A gas connection port 15 is provided at the lower back of the outer case 1 and can be connected to a gas outlet 15b by a gas hose 15a. The pipe is connected to a gas supply means 16 comprising an electromagnetic valve and a proportional valve, and gas is supplied to the burner 8 through a gas conduit 17. An operation and display unit 18 is provided in the front portion of the top plate 2, and an operation display circuit 19 a is provided as a part of control means in which various switches and indicators are arranged in the outer case 1 immediately below the top case 2. Reference numeral 19 is a control circuit that forms the core of the control means, and 20 is a room temperature detector comprising a thermistor, which is also provided in the exterior case 1. Reference numeral 21 denotes a power cord for supplying power to the control means 19.
[0029]
Next, the operation will be described.
[0030]
FIG. 2 is a flowchart showing the heating operation of the gas hot air heater in the embodiment of the present invention. When there is an operation instruction, the control circuit 19 first drives the blower fan 11 with the amount of ignition air (S01). The electromotive force value (TC) detected by the thermocouple 10 is determined (S02), and if the ignition detection threshold value or more continues for 60 seconds before the ignition operation, the thermocouple 10 is stopped as an abnormal thermoelectromotive force. If it is less than the ignition detection threshold, an inrush current is passed through the proportional valve (S03), and the valve body is fully opened for 1 second. In the meantime, the ventilation is continued and the air in the combustion chamber 7 is discharged outside the apparatus to purify the combustion chamber 7 (pre-purge operation). Thereafter, with the ignition means 9 turned on (S04), the solenoid valve is turned on and the proportional valve is set to the ignition gas amount (S05). When the discharge spark of the ignition means 9 ignites gas, a flame is formed in the burner 8. When the thermocouple 10 is burned, an electromotive force is generated, and the ignition is detected when the TC continues for more than 0.5 seconds at the ignition detection threshold (S06). The ignition detection threshold is 3 mV. Further, if 30 seconds of the non-ignition safety timer elapses (S07) while remaining below the ignition detection threshold, the non-ignition abnormality is stopped. After the ignition is detected, the first timer is set (S08), the combustion lamp provided in the operation display circuit 19a and disposed in the operation and display unit 18 is turned on, the ignition means 9 is turned off (S09), and the blower fan 11 is turned into a strong wind. The quantity and proportional valve are set to a strong gas quantity (S10), and combustion is performed with the maximum combustion quantity of the equipment. Thereafter, misfire detection (S11) is performed until the first timer elapses (S12), and if the misfire is not detected and the first timer time elapses, the proportional combustion operation is performed. In the proportional combustion operation, the room temperature is read by the room temperature thermistor 20 (S29), and the blower fan 11 and the proportional valve are controlled between strong and weak so that the room temperature becomes the set temperature (S30). Further, during that time, the TC continues to be less than the detection threshold value for 5 seconds (S31) to detect the disappearance, stop as an abnormal disappearance, and prevent the unburned gas from flowing out.
[0031]
When misfire is detected during the first timer count, the ignition operation is repeated again. The combustion lamp is turned on and off at a frequency of 0.5 Hz from lighting (S13), the solenoid valve and the proportional valve are turned off (S14), and the blower fan is set to the ignition air volume (S15). Here, 2 seconds of the standby timer is set (S16), TC is determined before the ignition operation (S17) as in S02, and if the ignition detection threshold value or more continues for 60 seconds, it is stopped as a thermoelectromotive force abnormality. On the other hand, if it is less than the ignition detection threshold, it waits for 2 seconds of the standby timer to elapse (S18), and performs a so-called pre-purge operation for 1 second (S19). Thereafter, the ignition means 9 is turned on (S20), the solenoid valve is turned on, and the proportional valve is set to the ignition gas amount (S21).
[0032]
Here, when the fuel gas is supplied and the burner 8 is re-ignited, ignition is detected by TC continuing for 0.5 second or more above the re-ignition detection threshold (S22). The re-ignition detection threshold is 8 mV. Further, if 30 seconds of the non-ignition safety timer elapses with the re-ignition detection threshold being less than (S23), the non-ignition abnormality is stopped. After the ignition is detected, the first timer is set (S24), the combustion lamp is turned ON, the ignition means 9 is turned OFF (S25), the blower fan 11 is set to a strong air volume, and the proportional valve is set to a strong gas volume (S26). During the reignition operation, the TC disappears during the first timer count and continues to be less than the detection threshold value for 5 seconds (S27), and the extinction is detected and stopped as an abnormal disappearance. If the disappearance is not detected and the first timer time elapses (S28), the proportional combustion operation is performed.
[0033]
Moreover, the commercially available gas hose used for the fuel supply to the gas hot air heater has an inner diameter of 6 mm, 7 mm, 8 mm, and a length of 0.6 m, 0.7 m, 1 m, 2 m, 3 m, 5 m, It is 8m and is stocked with the combination. The gas hose capacity with an inner diameter of 8 mm and a length of 8 m, which maximizes the internal capacity, is about 0.4021 × 10 ⁻³ m ³ . The calorific value of pure propane, which is the main component of LP gas having a large calorific value, is approximately 28.28 kW / m ³ (24320 kcal / m ³ ), and the calorific value in the gas hose is approximately 0.01137 kW. On the other hand, the maximum combustion amount of gas hot air heater the combustion amount is the most popular small is approximately 2.44kW / h (≒ 0.6778 × 10 -3 kW / s), the fuel gas in the gas hose Is supplied to the burner 8 in about 17 seconds and consumed. This is a calculation under the condition that takes the longest time to pass the fuel gas, but the first timer set value is set to 30 seconds in consideration of variations in equipment and gas components.
[0034]
FIG. 3 is a time chart showing the behavior of the electromotive force of the gas warm air heater in the embodiment of the present invention. The vertical axis represents TC (mV) detected by the thermocouple, and the horizontal axis represents elapsed time (seconds). Time 0 is a timing at which the operation is instructed, and indicates a change in TC when the flame of the burner 8 is misfired within 30 seconds after detection of ignition. After the ignition is detected, the TC increases stably in order to obtain the maximum combustion amount, and the TC decreases at the time of misfire.
[0035]
As shown here, the distinction between the combustion state and the misfire state can be clearly determined by TC. The behavior of TC in the phenomenon of misfiring after ignition due to air accumulation in the gas hose varies depending on the combination of the diameter and length of the gas hose, the amount of air, and the maximum combustion amount of the equipment, but almost shows the behavior in the range of this time chart. The trend is that the longer the combustion time, the higher the TC, and the higher the voltage level of the TC, the greater the degree of decrease per hour. Each chart turns off in the direction of decrease, and then the burner 8 flame disappears, so the air in the gas hose and the unburned gas from the gas plugs flow out, and the misfire condition is detected quickly. If the reignition operation is not performed, a gas odor due to gas outflow occurs.
[0036]
FIG. 4 is a flowchart showing the misfire detection operation of the gas warm air heater in the embodiment of the present invention, and specifically shows the contents of the misfire detection in S11. Misfire detection is performed after the blower fan 11 has a strong air flow and the proportional valve has a strong gas amount (S10 in FIG. 1) and the maximum combustion amount. First, the current TC (when ignition is detected) is set as a temporary TC maximum value (S32). Next, TC is read (S33) and compared with the TC maximum value (S34). If TC is larger, the TC maximum value is updated with TC (S35). Further, ΔTC, which is the difference between the TC maximum value and TC, is calculated (S36). If ΔTC is equal to or greater than the first detection threshold (S37), it is determined that misfire has occurred. In addition, it is determined that misfire has occurred even if TC is less than the second detection threshold. Further, the misfire detection is terminated when the first timer time has elapsed. The first detection threshold is 1 mV, and the second detection threshold is 3 mV, the same as the ignition detection threshold. Such an operation can be easily realized by a program of a microcomputer (not shown) mounted on the control circuit 19.
[0037]
As described above, after the ignition operation and the ignition detection, the maximum combustion amount is increased during the first timer time, the gas flow rate is increased, and the behavior of the electromotive force value (TC) detected by the thermocouple 10 is stably increased. Since misfire detection was performed based on TC and ignition operation was started again, when an air accumulation occurred in the gas hose and unstable fuel was supplied, misfire was detected with high accuracy at an early stage. When the gas is supplied, it becomes possible to ignite the burner 8 again, and it can be used continuously without abnormally stopping the equipment. In addition, by performing the reignition operation, the ignition detection threshold can be set to a relatively low level. Therefore, when gas is normally supplied stably, the ignition operation is quickly completed without delaying the ignition detection. There is no loss of features.
[0038]
In addition, the first timer for determining the reignition operation is set to 30 seconds, which is sufficiently longer than the time when the total gas capacity in the gas hose is supplied to the burner 8, so that the state of air accumulation in the gas hose (fuel gas and air The misfire can be detected regardless of the ratio, and the reignition operation can be performed reliably.
[0039]
In addition, misfire during the first timer time at the time of re-ignition has been determined to extinguish and stop abnormally. Therefore, the re-ignition operation is limited to one time. The ignition operation can be avoided, and the anxiety caused by the intermittent ignition sound that occurs when the re-ignition operation is repeated can be eliminated.
[0040]
Further, the maximum value of TC during the first timer time is searched, a misfire is detected by the decrease of TC from the maximum value, the re-ignition operation is performed, and the gas supply means 16 is closed. If the first detection threshold is set to 1 mV, misfire can be detected in about 2 seconds in the misfire after burning for 5 seconds after the ignition is detected, so the combustion gas is momentarily interrupted by a small amount of air and gas is immediately supplied from the gas plug. Even in such a case, the outflow of unburned gas can be reduced and the gas odor can be suppressed.
[0041]
In addition, the maximum combustion is performed during the first timer period, and the TC during stable gas supply rises stably. Therefore, the first detection threshold can be set small, and misfire can be detected with high sensitivity.
[0042]
In addition, since misfire is detected when TC falls below the second detection threshold that is the ignition detection threshold, the gas hose is short and the remaining amount of gas in the gas hose is small, and TC is greater than or equal to the first detection threshold from the ignition detection threshold. In the case of misfire without reaching the level, misfire detection can be performed earlier than waiting for a decrease in TC for the first detection threshold. In addition, when TC is about 4 mV and the voltage is low, the degree of decrease becomes more gradual, which is an effective means for speeding up the misfire detection time. In FIG. 2, when a misfire is detected immediately after detection of ignition, a detection time of about 4 seconds is required when the first detection threshold is set to 1 mV, and a detection time of about 4 seconds is required. However, when a determination is made with the second detection threshold (3 mV), about The misfire detection time can be improved by 1 second.
[0043]
Further, during the re-ignition operation, even if the initial TC determination (S17) ends immediately, the pre-purge operation for 1 second is performed after waiting for 2 seconds with the blower fan 11 kept at the ignition air flow, and the shortest time before the ignition means 9 is activated. Since 3 seconds of blowing time can be secured, the combustion gas, lean gas, and unburned gas generated by the first ignition and misfire can be sufficiently discharged, and the inside of the combustion chamber 7 can be cleaned and a stable reignition operation can be performed. . Since the TC level is increased during the reignition operation, the initial TC detection is determined at a high voltage (for example, the reignition detection level: 8 mV), and the reignition operation is performed quickly without waiting for the TC to decrease. When trying to do so, it becomes an effective means for securing the pre-purge time.
[0044]
Further, during the re-ignition operation, after the TC has decreased to the ignition detection threshold of 3 mV, the re-ignition detection threshold is increased to 8 mV and the ignition determination is performed. Therefore, the ignition means 9 operates until a sufficient increase in TC is obtained. Continuously, even when unstable gas supply is performed, reliable ignition detection can be performed. When the initial TC detection is determined at a high voltage (for example, the re-ignition detection level: 8 mV) and the re-ignition operation is attempted quickly without waiting for the decrease in TC, the detection timer time of the re-ignition detection (S22) By setting the duration to about 3 to 5 seconds, a sufficient operating time of the ignition means 9 can be ensured.
[0045]
In addition, when the re-ignition operation is started, the combustion lamp is blinked until the re-ignition detection (S22), so that the user can be visually informed that the re-ignition operation is being performed. It is possible to reduce the uncomfortable feeling that occurs repeatedly.
[0046]
【The invention's effect】
As described above, according to the first to seventh aspects of the present invention, when misfire is detected immediately after ignition is detected, the ignition operation is performed again. Even in this case, it is possible to ignite reliably by one operation instruction and to continue combustion stably, reducing the ignition failure and improving the usability of the device.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a gas hot air heater according to an embodiment of the present invention. FIG. 2 is a flowchart showing a heating operation of the gas hot air heater according to the embodiment. Time chart showing behavior of electromotive force of gas hot air heater [FIG. 4] Flow chart showing misfire detection operation of gas hot air heater in the same embodiment [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Exterior case 4 Air inlet 5 Hot air outlet 7 Combustion chamber 8 Burner 9 Ignition means 10 Thermocouple (flame sensor)
11 Blower fan (Blower unit)
12 Motor (Blowing means)
15 Gas connection port 15a Gas hose 16 Solenoid valve / proportional valve (gas supply means)
17 Gas conduit 19 Control circuit (control means)
19a Operation display circuit (control means)

Claims (7)

A combustion chamber facing the burner, ignition means and flame sensor in an outer case having an air inlet and a hot air outlet, and air sucked from the air inlet is supplied to the burner and heated in the combustion chamber. Blowing means for discharging air from the hot air outlet, gas supply means for supplying gas to the burner from a gas connection port provided in the outer case, and control means for controlling the operation of the device, the control means is an ignition operation After the ignition is detected, the maximum combustion amount is forcibly set during the first timer period, and when the misfire is detected during the first timer period, the ignition operation is repeated again. The first timer period is A gas hot air heater characterized in that it is longer than the time required for gas to be supplied to the burner equal to the capacity of a gas hose connected to the gas connection port and supplying fuel to the equipment . The gas hot air heater according to claim 1 , wherein the number of repetitions of the ignition operation is one. The gas hot air heater according to claim 1 or 2 , wherein the misfire is determined when the detection value of the flame sensor is decreased by a first detection threshold during the first timer period. The gas hot air heater according to claim 3 , wherein misfire is determined even when the detection value of the flame sensor falls below a second detection threshold value for determining ignition detection. Control means configured to perform blowing before the ignition means is actuated, the blowing time, to any one of claims 1-4 towards the re-ignition operation is characterized by longer than ignition operation of the first Gas hot air heater as described. The gas hot air heater according to any one of claims 1 to 5 , wherein an operation time of the ignition means is longer in the reignition operation than in the first ignition operation. Control means configured to perform display during the ignition operation, the contents to be displayed, according to any one of claims 1 to 6, characterized in that differs between the time of ignition operation and re-ignition operation of the first Gas hot air heater.

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