JPS63286610A - Safety device for open type combustion device - Google Patents

Abstract

PURPOSE:To improve safety, by a method wherein a temperature difference between the inside and the outside of a filter is detected by inner and outer thermistors, provided at the inside and the outside of the filter for a ventilation fan while a dust monitor, conuerting the temperature difference into the amount of adhesion of dust and indicating the same, is provided in the title device. CONSTITUTION:A room temperature thermistor 24 detects room temperature at all times and a detected value 26 is compared with a set temperature input 27 in a comparator 28 and the combustion amount 29 of a burner is determined to effect combustion 30. The rotating number 31 of a motor 5 suitable for the amount of combustion is also determined. An inner thermistor 22 and an outer thermistor 23 monitor the temperatures of inside and outside of a filter 7 and the inputs of these thermistors (B', B'') 32 are inputted into a micro-computer 14 to operate a temperature difference B=B'-B'' 33. Then, the value of corrected temperature difference B- Bx 34 is operated in the micro-computer 14 in accordance with the amount of combustion. This correction is incorporated and memorized previously in the micro-computer 14. The value of operation is inputted into an amount of dust indicating circuit 17 to indicate it in accordance with Bx 35 by pointer, a LED or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion device that takes in room air, burns it, and discharges the combustion gas into the room for heating.

BACKGROUND OF THE INVENTION In general, this type of combustion appliance has a main body consisting of an external device and a stand 2, a burner 3, a combustion tube 4, a motor 5 and a fan 6 for supplying indoor air, and a protection for the fan 6, as shown in Fig. 4. It has a filter 7 for removing dust from the air, and a looper 8 for discharging warm air into the room.

In a combustion appliance having such a structure, combustion heat A generated by the burner 3 and the combustion tube 4 is mixed with indoor air B sent by the fan 6 to become warm air C and blown into the dormitory. In this case, the ventilation guide plate 9 is maintained at a certain temperature by the combustion heat A and the indoor air B. That is, the guide plate 9
The temperature is determined by the relationship between combustion heat A and indoor air B. However, the flow rate of indoor air is
It is determined by the amount of air passing through the filter 7 and the combustion heat A, and the combustion heat A is uniquely determined, but the amount of air passing through the filter 7 is determined by the coarseness of the mesh of the filter 7. The roughness of the mesh remains as it was when it was initially designed, but in reality, the dust inside the room gradually becomes clogged with the mesh, reducing the amount of air blown. However, special firing heat A
Since is always constant, the temperature of the air guide plate 9 gradually increases as it is used. Therefore, the temperature of the hot air C discharged into the room also gradually increases.

In preparation for such a case, a bimetallic thermostat 10 is installed on the blower guide plate 9, and when the blower guide plate 9 reaches an abnormal temperature due to dust, the thermostat 10 is activated to stop the operation of the entire circuit and stop the combustion system. , to notify you of a decrease in air flow due to dust.

Generally, the combustion system is stopped in such a case, so the thermostat 10 operates even if the air blowing stops due to a failure of the air blowing motor 5, in addition to dust, and plays the role of maintaining the safety of the equipment and users. I am doing it.

Also, a thermistor near the thermostat 10.

11 is the provision. The operating temperature of this thermistor 11 is, for example, 90°C compared to 110°C of the thermostat 10, and the dust accumulated on the filter 7 causes the air blow h1 to
It is designed to detect when there is insufficient dust and act as a dust detector.

Therefore, during normal use, the general user knows when it is time to clean the dust from the display or alarm caused by this dust detection, and can recognize abnormalities in parts such as the motor or combustion abnormalities by the operation of the thermostat 10.

FIG. 5(a) shows a conventional circuit, in which a power supply 15, an operation switch 16, a thermostat 10, and a load group 13 such as an oil supply device form a closed loop. A control circuit 12 whose main part is a microcomputer (hereinafter referred to as microcomputer) 14 is connected in parallel with the load group 13 . Control circuit 1
2 is connected to the thermistor 11 for detecting dust.

A display circuit 17 indicates the state of dust accumulation. The thermostat 10 detects an abnormality, and when it operates, not only the load group 13 but also the control circuit 12 are turned off, so it is safe. In particular, the reason why a bimetallic thermostat 10 is used as a final safety feature is that electronic circuits that have a memory element such as a microcomputer or have a complex structure may malfunction or run out of control due to external or airborne noise, and may not operate normally. This is because it may cause completely unexpected behavior.

Parts other than electronic circuits, especially bimetallic ones, cannot be operated safely in such cases! It is necessary to stop the combustion using a mechanical part such as a burner. For this purpose, a bimetallic thermostat 10 is used.

FIG. 5(b) is an example of the connection between the thermistor 11 and the microcomputer 14. If the DC power supply is at point a-b,
The microcomputer 14, the thermistor 11-c, the resistor 18, the resistor 19-d, and the resistor 20 are connected between the points -b and the microcomputer 14, respectively, in series. The positive and negative input terminals of the operational amplifier 21 are connected to points c and d, and the eight output points thereof are connected to the input terminals of the microcomputer 14. In this circuit, when the resistance value of the thermistor 11 becomes small due to dust and the potential at point C exceeds the potential at point d, the output eAW changes from LO to Hi, and the microcomputer 14
outputs to the dust amount display circuit 17 that dust has accumulated.

Problems to be Solved by the Invention However, this safety device does not allow dust to adhere until the thermistor or thermostat detects an abnormal temperature rise and issues an alarm or stops combustion. It is difficult for the user to recognize the condition, and the user may mistakenly think that cleaning is not necessary until an alarm is generated, and the user may become less careful about the dust that gradually accumulates. It is expected that this will happen.

The present invention was invented in view of these points, and is aimed at improving safety.

Means for Solving the Problems In order to achieve the above object, the present invention uses inner and outer thermistors installed inside and outside the fill of a blower fan to detect the temperature difference between the inside and outside of the fill, and calculate the temperature. By replacing the difference with the amount of attached dust, a device equipped with a dust monitor that displays the amount of attached dust can be created.

Effect: With the above configuration, the present invention allows the user to constantly know the amount of dust attached to the filter during combustion by looking at the dust monitor during combustion, and urges the user to clean the dust from the filter. Safer and more comfortable heating can be performed.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. Note that the same parts as in the conventional example described above are given the same reference numerals, detailed explanations are omitted, and different parts will be mainly explained.

In FIG. 1, 22 and 23 are inner and outer thermistors installed to detect the temperature of the indoor air taken in by the blower fan 6. The inner thermistor 22 is installed inside the filter 7, and the outer thermistor 23 is installed inside the filter 7. is installed outside the fir 7.

24 is a room temperature thermistor.

In the above configuration, the internal and external thermistors 22 and 23 indicate that when there is no dust attached to the filter 7, the flow of air from the ventilation fan 6 is smooth, and the detected temperatures of both are the same value (B'=B'). Become. However, as the warm-air heater is used, if dust adheres to the filter 7, the amount of air blown by the fan 6 decreases, and as a result, the combustion heat A is transferred to the looper 8.
It becomes hot air C from the combustion part and blower fan 6 without blowing out.
The ambient temperature (B') of the area increases. The inner thermistor 22 detects this temperature rise. However, the outer thermistor 23 does not detect a temperature rise like the inner thermistor 22 because the heat generated by the dust attached to the filter 7 is blocked. In other words, the temperature difference (B'>B') generated inside and outside of this fill 7 can be detected by the two thermistors 22.2 and 22.
3 is used for detection. Moreover, as the amount of attached dust gradually increases, the ambient temperature of the inner thermistor 22 (
B') further increases, and the detected temperature difference between the inner and outer thermistors 22, 23 gradually increases.

Furthermore, since this temperature difference may increase or decrease depending on the combustion heat A, it is necessary to correct the detected temperature difference according to the amount of combustion at that time.

The control procedure will be explained using the flowchart of FIG. 2 and FIG. 3, including the above.
When closed, the control circuit 12 passes through the thermostat 10.
A voltage is applied to the load group 13, and the entire operation is started 26 by the control circuit 12 consisting of a microcomputer.

The room temperature thermistor 24 constantly detects the room temperature, and compares 28 the difference between this value 26 and a desired set temperature 27.

The combustion amount 29 of the burner is determined by this difference, and the process shifts to combustion aO. Also, the rotation speed of the motor 6 is 3, which is suitable for this combustion amount.
1 is also determined. During operation in this manner, the inner and outer thermistors 22 and 2a monitor the temperature inside and outside of the filter 7. Then, these outputs are input 32 to the microcomputer 14, and the temperature difference is calculated 33. Then, the microcomputer 14 further calculates 34 the value of the temperature difference after correction according to the combustion amount at that time. This correction has been previously incorporated and stored in the microcomputer 14. This calculated value is input to the dust amount display circuit 17, and the display section 17 displays a display 35 using a pointer, an LED, or the like. In this way, the input data of the thermistor is constantly displayed.

Effects of the Invention As described above, the present invention not only prevents abnormal temperature rises inside the main body due to dust adhesion and combustion failures due to lack of air, but also allows the user to constantly monitor the amount of dust adhesion, thereby reducing fill-up. Awareness about dust cleaning can be raised.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a hot air heater adopting an embodiment of the present invention, Fig. 2 is a flowchart explaining its operation, Fig. 3 is a circuit diagram showing its configuration, and Fig. 4 is a conventional hot air heater. A sectional view of the heater, and FIG. 5 is its circuit diagram. 6...Blower fan, 7...Filter, 12...Control circuit, 14...Microcomputer, 17...Dust amount display circuit , 22...
・Thermistor, 23...Thermistor. Name of agent: Patent attorney Toshio Nakao and 1 other person3-
Bars 4-P boundary height 5-Blower motor 6-Blowing calm fan 7-Filter 10--Thermostat 1f -Thermistor n-Inner armister n-Outer thermistor Fig. 1 Fig. 2 +2- ν1 Healthy circuit +7-Salt amount Display U3 bribe n- thermistor figure 3 ""f-=:zp 1ot r. Figure 4 (mu)

Claims (1)

[Claims] A combustion part such as a burner, a blower fan that mixes indoor air with the combustion exhaust gas of the combustion part and discharges warm air, and a filter that purifies the indoor air by the blower fan.
A thermistor is installed inside the filter, on the combustion section side and outside, and a control circuit based on a microcomputer that reads the temperature difference obtained from the output of the inside and outside thermistors, and the output from this control circuit. A safety device for an open type combustion appliance, which is equipped with a dust amount display circuit that is activated by receiving a dust amount.