JPH09159156A - Combustion safety device for gas implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the ambient temperature at a set temperature without displacing a heating quantity from a desired quantity particularly when it is applied to a heater by eliminating the switching to a strong combustion state and returning to a weak combustion state when oxygen concentration is higher than a reference concentration and continuing a strong combustion state for a predetermined time when it is the reference concentration or lower. SOLUTION: The thermoelectromotive force in a strong combustion state when oxygen concentration is reduced to 18% of oxygen shortage concentration is previously set as a reference value ta. Even if it is a weak combustion state, the combustion state is periodically switched to the strong combustion state. When the thermoelectromotive force in the strong combustion state is lowered to the ta, it is judged that the oxygen concentration becomes 18% or lower, and a fan heater is stopped. When the oxygen concentration is higher than the concentration near the inversion concentration CI, the heater is not necessarily stopped. Then, the reference concentration is set so that the inversion concentration CI is disposed in a predetermined range A as a center, and when the oxygen concentration is higher than the reference concentration, the operation of the fan heater is not stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention allows a thermocouple to face a burner whose combustion amount can be switched between strong and weak, and intermittently switches the combustion state from, for example, a weak combustion state to a strong combustion state to generate heat generated by the thermocouple. The present invention relates to a combustion safety device for gas appliances that detects an oxygen-deficient state when an electromotive force is below a reference value.

[0002]

2. Description of the Related Art For example, in the case of a hot air fan heater which mixes combustion gas of a burner with air and blows it as warm air into a room, the ventilation in the room is poor and the oxygen concentration in the air is lowered. Since combustion becomes unstable in this state, it is desirable to automatically stop combustion when the oxygen concentration falls below a predetermined oxygen deficiency concentration (for example, 18%). By the way, it is known that when the burner is exposed to a thermocouple, the thermoelectromotive force is reduced as the oxygen concentration is reduced. The decrease in thermoelectromotive force due to the decrease in oxygen concentration appears more markedly in the strong combustion state that requires more oxygen than in the weak combustion state.
By the way, the thermoelectromotive force in the strong combustion state is larger than the thermoelectromotive force in the weak combustion state in the normal combustion state in which the oxygen concentration is sufficient, but the oxygen concentration is higher than the oxygen deficiency concentration depending on the mounting position of the thermocouple. It is possible to make the thermoelectromotive force in the strong combustion state higher or lower than the thermoelectromotive force in the weak combustion state. For example, when the thermoelectromotive force at the oxygen deficiency concentration is lower in the strong combustion state than in the weak combustion state, the thermoelectromotive force of the thermocouple is the value of the thermoelectromotive force in the strong combustion state at the oxygen deficiency concentration. When the temperature drops to (reference value), it is set to stop the operation of the hot air fan heater by judging that it is an oxygen deficiency state, and the thermoelectromotive force is higher than the reference value even if the oxygen concentration drops to the oxygen deficiency concentration in the weak combustion state. Therefore, it is necessary to intermittently switch the combustion state to the strong combustion state during the weak combustion state to check whether the thermoelectromotive force falls to the reference value. That is, when the reference value is set in the weak combustion state, the oxygen concentration is higher than the oxygen deficiency concentration in the strong combustion state, but the oxygen concentration is cut off prematurely. Further, when the reference value is set for each of the strong combustion state and the weak combustion state, the reference value is immediately switched at the time of switching from the strong combustion state to the weak combustion state, but since the change of the thermoelectromotive force is slow, the reference value is also quickly cut.

When the thermoelectromotive force at the oxygen deficient concentration is higher in the strong combustion state, conversely, the value of the thermoelectromotive force in the weak combustion state at the oxygen deficient concentration is used as a reference value in the weak combustion state. When the thermoelectromotive force decreases to the reference value, the operation of the warm air fan heater is stopped, and in the strong combustion state, the combustion state is intermittently switched to the weak combustion state to determine whether the thermoelectromotive force decreases to the reference value. Need to check.

By the way, the thermoelectromotive force at the oxygen deficient concentration can be made to be the same in the strong combustion state and the weak combustion state depending on the mounting position of the thermocouple. In that case, regardless of the strength of the combustion state. When the thermoelectromotive force drops to the reference value, the operation of the warm air fan heater may be stopped. However, since the degree of decrease in thermoelectromotive force due to the decrease in oxygen concentration is greater in the strong combustion state, it is possible to accurately detect the oxygen deficiency state by intermittently switching to the strong combustion state during the weak combustion state.

[0005]

However, when the strong combustion state is intermittently switched to the strong combustion state in the middle of the weak combustion state, the heat generation amount becomes larger than the desired value, and conversely, the weak combustion state is intermittently generated in the middle of the strong combustion state. When switched to, the calorific value becomes less than the desired value. Therefore, in the case of a warm air fan heater,
Since the calorific value deviates from the desired value, the room temperature does not reach the desired temperature and the comfort is impaired.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a burner whose combustion amount can be switched between strong and weak and a thermocouple, and intermittently switches the combustion state from a weak combustion state to a strong combustion state. , In the combustion safety device for gas appliances that detects that the thermoelectromotive force generated by the thermocouple is lower than the standard value, the degree of decrease in thermoelectromotive force due to the decrease in oxygen concentration is weak. The strong electromotive force in the strong combustion state is larger than that in the strong combustion state, and the oxygen electromotive force in the strong combustion state is lower than the reversal concentration which is higher than the predetermined oxygen deficiency concentration. A thermocouple is attached so that the oxygen concentration is lower than that, and the oxygen concentration is higher than the reference concentration set within a predetermined range centered on the reversal concentration depending on the degree of change in thermoelectromotive force due to switching from the weak combustion state to the strong combustion state. To release the switch to strong combustion state when it is determined return the combustion state in the weak combustion state, characterized in that it continues for a predetermined time strong combustion state when it is determined that more than the reference concentration.

The reference density may be matched with the inversion density.

Further, the thermocouple is exposed to a burner whose combustion amount can be switched between strong and weak, and the combustion state is intermittently switched from the strong combustion state to the weak combustion state, so that the thermoelectromotive force generated by the thermocouple falls below the reference value. In the combustion safety device for gas appliances that detects an oxygen deficiency state due to the above, the degree of decrease in thermoelectromotive force due to a decrease in oxygen concentration is greater in the strong combustion state than in the weak combustion state, and the oxygen When the concentration is higher than the oxygen deficient state, a thermocouple is installed so that the thermoelectromotive force in the strong combustion state always exceeds the thermoelectromotive force in the weak combustion state, and the heat generated when switching from the strong combustion state to the weak combustion state When the reduction speed of the electromotive force is faster than the predetermined speed, the switching to the weak combustion state is canceled and the combustion state is returned to the strong combustion state,
When the decreasing speed is equal to or lower than the predetermined speed, the weak combustion state is continued for a predetermined time.

Further, in a combustion safety device for a gas appliance, a thermocouple is exposed to a burner whose combustion amount can be switched between strong and weak, and a thermosafe electromotive force generated by the thermocouple detects an oxygen deficient state. A thermocouple is installed so that the thermoelectromotive force in the strong combustion state is different from that in the weak combustion state. It is characterized in that the electric power is used as a comparison value, and when the amount of decrease in thermoelectromotive force after a predetermined time with respect to the comparison value exceeds a predetermined value, the combustion state is switched to the other combustion state for a predetermined time.

The comparison value may be updated after switching to the other combustion state and returning the combustion state.

When the inversion concentration exists while the oxygen concentration decreases from the normal state to the oxygen deficiency concentration, if the oxygen concentration is near the inversion concentration, the oxygen concentration is higher than the oxygen deficiency concentration. There is no need to extinguish the fire. Therefore, if the reference concentration is set near the reversal concentration and it is determined that the oxygen concentration is higher than the reference concentration due to the degree of change in thermoelectromotive force due to switching from the weak combustion state to the strong combustion state, the weak combustion state is changed to the strong combustion state. The increase in the amount of heat generation is suppressed by canceling the switching to the state and returning to the weak combustion state.

When the reference concentration is set to match the reversal concentration, the oxygen concentration at that time is higher or lower than the reference concentration, depending on whether the thermoelectromotive force increases or decreases due to switching to the strong combustion state. By knowing which one, the timing to release the switch to the strong combustion state can be accelerated.

Further, there is no reversal concentration in a range higher than the oxygen deficiency concentration, and while the oxygen concentration decreases from the normal state to the oxygen deficiency concentration, the thermoelectromotive force in the strong combustion state is always the heat in the weak combustion state. If it exceeds the electromotive force, the difference in thermoelectromotive force between the two states decreases as the oxygen concentration decreases. Then, as the oxygen concentration decreases, the decreasing rate of the thermoelectromotive force at the time of switching from the strong combustion state to the weak combustion state becomes slower. Therefore, if the decrease rate of the thermoelectromotive force is faster than the predetermined speed, there is no risk of oxygen deficiency, so the heat generation amount is prevented from decreasing by canceling the switch to the weak combustion state and returning the combustion state to the strong combustion state. It was decided to.

If a thermocouple is attached so that the thermoelectromotive force in the oxygen deficient state differs between the strong combustion state and the weak combustion state, the thermoelectromotive force falls below the reference value in the lower combustion state. I have to see if However, it can be seen that the oxygen concentration is higher than the oxygen deficiency concentration until the thermoelectromotive force in the higher combustion state decreases to some extent, so compare the thermoelectromotive force at a predetermined time while the higher combustion state continues. As the value, the combustion state is not switched until the decrease amount of the thermoelectromotive force after a predetermined time exceeds the predetermined value with respect to the comparison value, and the number of times of switching is reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1, reference numeral 1 denotes a gas warm air fan heater having a combustion casing 2 inside. A burner 3 is provided in the combustion casing 2, and the combustion gas of the burner 3 discharged from the outlet 21 of the combustion casing 2 and the air sucked from the intake port 11 opening on the back surface of the fan heater 1 are mixed. The generated warm air is blown by the blower fan 4 into the warm air outlet 12
Is blown into the room from. By the way, the thermocouple 5 is provided so as to face the burner 3, and the voltage of the thermoelectromotive force generated from the thermocouple 5 changes corresponding to the temperature near the tip of the thermocouple 5.

As shown in FIG. 2, the burner 3 has a safety valve 61 and an electromagnetic on-off valve 62 for the gas supply pipe 6.
Connected through. A bypass passage 63 is provided in parallel with the opening / closing valve 62. When the opening / closing valve 62 is open, gas is supplied to the burner 3 through the opening / closing valve 62 and the bypass passage 63. A strong combustion state is set (FIG. 2 (a)). Further, when the opening / closing valve 62 is closed, the gas is supplied to the burner 3 only through the bypass passage 63, so that the combustion state becomes weak (FIG. 2 (b)). The on-off valve 62
Is opened and closed by a signal from the drive unit 71 controlled by the control unit 7. The control unit 7 controls the operation of the drive unit 71 based on the deviation between the set temperature and the actual room temperature, and the burner. The combustion state of No. 3 is switched between the strong combustion state and the weak combustion state.

The state of the flame in the strong combustion state and the weak combustion state is shown in FIG. 2 (a) in the normal combustion state where the oxygen concentration is sufficient.
When the oxygen concentration is reduced as in the case of FH / FL in (b) and the indoor ventilation is poor, the combustion speed slows down and the flame spreads due to the so-called lift-up phenomenon, resulting in FH ′.
・ It becomes like FL '. In the present embodiment, in the normal combustion state, the tip of the thermocouple 5 is arranged in the outer flame of the FL in the weak combustion state and in the inner flame of the FH in the strong combustion state. The temperature of the inner flame of FH is higher than the temperature of the outer flame of FL. Next, when the oxygen-deficient state is reached, the flame lifts up, and the tip of the thermocouple 5 is located in the inner flame of FL 'in the weak combustion state, and between the FH' and the burner in the strong combustion state. It will be located in the unburned part where the temperature is extremely low. When changing the reversal concentration, if the tip of the thermocouple 5 is brought close to the external flame, for example, the reversal concentration shifts to the right side in the figure, that is, to the lower concentration due to the influence of the high temperature external flame. The decrease in the thermoelectromotive force of the thermocouple 5 due to the decrease in oxygen concentration is more remarkable in the strong combustion state that requires more oxygen. When the position of the thermocouple 5 is adjusted in this manner, the thermoelectromotive force of the thermocouple 5 decreases as the oxygen concentration decreases, as shown in FIG. 3, but the thermoelectromotive force changes in the strong combustion state. Since H has a greater degree of decrease than L, which indicates a change in thermoelectromotive force in the weak combustion state, the thermoelectromotive force in the strong combustion state is larger than in the weak combustion state when the oxygen concentration is sufficient, but is indicated by CI. The level relationship of the thermoelectromotive force is reversed at the inversion concentration, and the two lines intersect in FIG. Therefore, the thermoelectromotive force in the strong combustion state when the oxygen concentration is reduced to 18%, which is the oxygen deficiency concentration, is preset as the reference value ta, and the combustion state is periodically increased even in the weak combustion state. When the combustion state is switched to and the thermoelectromotive force in the strong combustion state is reduced to the ta, it is determined that the oxygen concentration is 18% (oxygen deficiency concentration) or less, and the operation of the fan heater 1 is stopped. . By the way, when the oxygen concentration is higher than the concentration near the reversal concentration CI, it is not necessary to stop the operation of the fan heater 1. Therefore, the reference concentration is set so as to be located within the predetermined range A around the inversion concentration CI, and the operation of the fan heater 1 is not stopped when the oxygen concentration is higher than the reference concentration.

By the way, when the reference concentration is made to coincide with the reversal concentration CI as shown in FIG. 3, if the thermoelectromotive force increases by switching from the weak combustion state to the strong combustion state, the oxygen concentration is higher than the reference concentration, and conversely. If the thermoelectromotive force decreases, it can be determined that the oxygen concentration is lower than the reference concentration. Therefore, FIG.
As shown in, the weak combustion state (LB) to the strong combustion state (H
When the thermoelectromotive force started to rise by switching to B), it was judged that the oxygen concentration was higher than CI, and immediately the switching operation to the strong combustion state was canceled to restore the combustion state to the weak combustion state. Further, when the thermoelectromotive force is reduced by switching to the strong combustion state, it is determined that the oxygen concentration falls below the reference concentration and is close to the oxygen deficient state, and the strong combustion state is maintained for a predetermined time (for example, 1 minute) without being released. Hold the combustion state. When the thermoelectromotive force is higher than the reference value ta even after switching to the strong combustion state, the oxygen concentration is higher than the oxygen deficiency concentration and the weak combustion state is restored again. When it falls below the reference value ta, the operation of the fan heater 1 is immediately stopped at that point (SB). In this way, as soon as the thermoelectromotive force rises due to switching to the strong combustion state, the switching to the strong combustion state is canceled immediately, so that the total time for switching to the strong combustion state can be minimized. When the room is warm and the weak combustion state is sufficient, the time of the strong combustion state is shortened, and further warming of the room is avoided as much as possible. Further, the switching from the weak combustion state to the strong combustion state may be performed at a constant cycle, but if the switching is canceled midway because the oxygen concentration is sufficient, the cycle until the next switching is extended, For example, if the fixed cycle is 10 minutes, the time until the next switching after the switching is canceled may be about 20 minutes.

Although the reference density is made to coincide with the inversion density CI as shown in FIG. 3 in the above embodiment, another density may be set as the reference density within the range A. In this case, if a density higher than the inversion density CI is set as the reference density,
Even if the thermoelectromotive force when switching from the weak combustion state to the strong combustion state rises, if the rate of rise of the thermoelectromotive force is less than or equal to a predetermined rate or the rise width is less than or equal to a predetermined value, oxygen It is possible to know that the concentration is below the reference concentration. Further, when the reference concentration is set to a concentration lower than the reversal concentration CI, the decrease rate of the thermoelectromotive force due to switching from the weak combustion state to the strong combustion state is equal to or higher than a predetermined speed, or the decrease width is equal to or less than a predetermined value. In some cases it can be seen that the oxygen concentration has fallen below the reference concentration.

On the other hand, depending on the installation position of the thermocouple 5, as shown in FIG. 5, when the oxygen concentration is higher than the oxygen deficiency concentration (18%), the thermoelectromotive force in the strong combustion state is always in the weak combustion state. It is possible to exceed the thermoelectromotive force. In this case, the thermoelectromotive force when the weak combustion state is set at the oxygen deficiency concentration is set as the reference value ta, and the strong combustion state is intermittently switched to the weak combustion state to check the thermoelectromotive force.
However, when the oxygen concentration is sufficiently high, the difference in thermoelectromotive force between the two states is large, and the amount of decrease in thermoelectromotive force due to switching from the strong combustion state to the weak combustion state is large, so the rate of decrease is large (θ1). As the oxygen concentration decreases, the amount of decrease is small, and the decrease rate is small (θ2). Therefore, as shown in FIG. 6, when the strong combustion state is switched to the weak combustion state and the rate of decrease in thermoelectromotive force is equal to or higher than the predetermined rate, it is determined that the oxygen concentration is high and the switching to the weak combustion state is canceled. Return to the strong burning state. As a result, when the oxygen concentration is high (that is, when it is not necessary to continue detecting the oxygen concentration), the time for the weak combustion state to see the oxygen deficiency state during strong combustion is immediately increased because the room temperature is low. Since it returns to the strong combustion state, there is no need to lower the room temperature.On the other hand, if the rate of decrease of the thermoelectromotive force falls below the predetermined speed, the weak combustion state is continued for the above predetermined time, and the thermoelectromotive force in the weak combustion state is the reference value The operation of the fan heater 1 is immediately stopped when the temperature falls below ta.

Although not shown, the reversal concentration CI in FIG. 3 can be made equal to the oxygen deficiency concentration depending on the installation position of the thermocouple 5. In that case, the operation of the fan heater 1 may be stopped if the thermoelectromotive force falls below the reference value ta regardless of the strength of the combustion state, and therefore it is not necessary to switch the combustion state intermittently. However, since the change in thermoelectromotive force with respect to the change in oxygen concentration in the strong combustion state is larger than the change in the weak combustion state, it is better to switch from the weak combustion state to the strong combustion state intermittently and check the thermoelectromotive force. The missing state can be accurately detected. In this case, it is determined whether or not to cancel the switching operation midway depending on the magnitude of the rising speed of the thermoelectromotive force due to the switching from the weak combustion state to the strong combustion state.

By the way, as shown in FIG. 3 above, paying attention to the fact that the thermoelectromotive force decreases when the oxygen concentration decreases even in the weak combustion state, as shown in FIG. The thermoelectromotive force at P1 is stored as a comparison value,
It is determined whether or not the amount of decrease in the thermoelectromotive force at time P2 after the predetermined cycle has decreased by a predetermined value, and if not decreased, the thermoelectromotive force at time P3 after the predetermined cycle is compared with the comparison value. To do. Then, when it is lower than the comparison value by a predetermined value or more, the combustion state is switched to the strong combustion state for a predetermined time. Then, the thermoelectromotive force at the time point P3 when switching to the strong combustion state is stored as a new comparison value, and P at the time point P4 after a predetermined period.
3, the combustion state is switched to the strong combustion state again when the thermoelectromotive force at P5 has decreased by a predetermined value or more with respect to the comparison value at P3 when not decreasing. This makes P3
Since it is not necessary to switch to the strong combustion state up to, the number of times of switching to the strong combustion state can be minimized.

If it is adopted in the case shown in FIG. 5, the mode is switched to the weak combustion state when the decrease amount of the thermoelectromotive force in the strong combustion state exceeds a predetermined value.

In the above embodiment, the case where the present invention is applied to the warm air fan heater has been described, but it may be applied to other types of heaters.

[0025]

As is apparent from the above description, according to the present invention, the combustion state is switched when the combustion state is intermittently switched to detect the oxygen deficiency state from the thermoelectromotive force generated by the thermocouple. Since the number of times and the extended time of the switched combustion state can be minimized, especially when applied to a heater, the calorific value does not deviate from the desired amount, and the room temperature can be maintained at the set temperature.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between a burner and a thermocouple.

FIG. 3 is a diagram showing a relationship between oxygen concentration and thermoelectromotive force.

FIG. 4 is a diagram showing changes with time of thermoelectromotive force.

FIG. 5 is a diagram showing another relationship between oxygen concentration and thermoelectromotive force.

FIG. 6 is a diagram showing another change with time of thermoelectromotive force.

FIG. 7 is a diagram showing another form of temporal change of thermoelectromotive force.

[Explanation of symbols]

 1 Hot Air Fan Heater 2 Combustion Casing 3 Burner 4 Blower Fan 5 Thermocouple 6 Gas Supply Pipe 7 Controller

Claims (5)

[Claims] 1. A thermocouple is exposed to a burner whose combustion amount can be switched between strong and weak, and the combustion state is intermittently switched from a weak combustion state to a strong combustion state so that the thermoelectromotive force generated by the thermocouple falls below a reference value. In the combustion safety device for gas appliances that detects an oxygen deficiency state due to the above, the degree of decrease in thermoelectromotive force due to a decrease in oxygen concentration is greater in the strong combustion state than in the weak combustion state, and the oxygen At a concentration lower than the reversal concentration, which is higher than the specified oxygen deficiency concentration, a thermocouple is installed so that the thermoelectromotive force in the strong combustion state is lower than the thermoelectromotive force in the weak combustion state. If it is determined that the oxygen concentration is higher than the reference concentration set within a predetermined range centered on the reversal concentration by the degree of change in thermoelectromotive force due to switching to the combustion state, switch to the strong combustion state. A combustion safety device for a gas appliance, which is released to return the combustion state to a weak combustion state, and when the concentration is judged to be below the reference concentration, the strong combustion state is continued for a predetermined time. 2. The combustion safety device for a gas appliance according to claim 1, wherein the reference concentration is matched with the reversal concentration. 3. The thermocouple is exposed to a burner whose combustion amount can be switched between strong and weak, and the burning state is intermittently switched from a strong burning state to a weak burning state, so that the thermoelectromotive force generated by the thermocouple falls below a reference value. In the combustion safety device for gas appliances that detects an oxygen deficiency state due to the above, the degree of decrease in thermoelectromotive force due to a decrease in oxygen concentration is greater in the strong combustion state than in the weak combustion state, and the oxygen When the concentration is higher than the oxygen deficient state, a thermocouple is installed so that the thermoelectromotive force in the strong combustion state always exceeds the thermoelectromotive force in the weak combustion state, and the heat generated when switching from the strong combustion state to the weak combustion state When the reduction speed of electromotive force is faster than a predetermined speed, switching to the weak combustion state is canceled and the combustion state is returned to the strong combustion state, and when the reduction speed is less than the predetermined speed, the weak combustion state is continued for a predetermined time. Features Combustion safety device for gas appliances. 4. A combustion safety device for a gas appliance, in which a thermocouple is exposed to a burner whose combustion quantity can be switched between strong and weak, and a thermoelectromotive force generated by the thermocouple detects that the gas is in an oxygen-deficient state. A thermocouple is installed so that the thermoelectromotive force in the strong combustion state is different from that in the weak combustion state. A combustion safety device for a gas appliance, wherein electric power is used as a comparison value, and when the amount of decrease in thermoelectromotive force after a predetermined time with respect to the comparison value exceeds a predetermined value, the combustion state is switched to the other combustion state for a predetermined time. 5. The combustion safety device for a gas appliance according to claim 4, wherein the comparison value is updated after the combustion state is switched back to the other combustion state and returned to the combustion state.