JPS6230672Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a forced convection hot air heater that uses combustion heat as a heat source for hot air.

This type of heater, for example one that uses combustion heat, performs combustion in the combustion section and exhausts the combustion exhaust gas through a heat exchanger, etc., while sucking indoor air with a blower fan installed on the back side of the main unit. combustion part,
Warm air is blown out to the front of the main body through the area around the heat exchanger. However, at the same time as ignition or when the vicinity of the combustion part reaches a certain temperature,
This type of heater that operates with a blower fan has the disadvantage that cold air is emitted immediately after the combustion starts, causing discomfort.

This is because, as shown in Figure 1, the number of rotations of the fan is always constant regardless of the temperature and calorific value of the combustion section. Temperature drops.

The present invention has been made to eliminate the above-mentioned drawbacks, and includes a temperature sensing element to control the air volume of the convection fan to prevent cold air from being blown out when the heating source starts up.

FIG. 2 shows an example of this. In the same figure,
Reference numeral 1 denotes a temperature detection element (for example, a thermistor), which is provided near the hot air outlet of the main body, for example, inside the louver. The installation position of this element 1 is close to a heating part, for example, a combustion part, and the temperature can be detected quite accurately from the hot air of the combustion part even without blowing air. Of course, if the blower fan operates and generates warm air, the temperature of this warm air will be sensed. 2 is the above-mentioned ventilation fan, and 3 is its rotation control circuit. This circuit 3 increases or decreases the rotational speed of the fan 2 according to the output of the phototransistor 4, and it is possible to control the amount of air blown almost steplessly. The phototransistor 4 is paired with a photodiode 5 to form a photocoupler 6.

The basic concept of air volume control in this embodiment is to change the light emitting output of the photodiode 5 in accordance with the output of the element 1, and to change the output of the phototransistor 4 based on this light emitting output.
The aim is to obtain an air flow rate that corresponds to the detected output.

Incidentally, in the figure, there are three differential amplifiers, 7, 8, and 9 from the left, of which 7 operates as an operational amplifier and the others operate as comparators. That is, the comparator 8 determines the rotation start temperature of the blower fan 2 when heating of the heating section starts, for example, when igniting, and simultaneously stops the blower fan 2 when heating is stopped, for example, when extinguishing a fire. Further, the comparator 9 determines whether the hot air temperature has become abnormally high due to a clogged filter or the like.

Note that the on/off determination level of the blower fan may be changed depending on when the ignition is ignited and when the fire is extinguished. On the other hand, when a fire is extinguished, no heat is generated and no further heating is required, so it is desirable to lower the air blowing start level when a fire is ignited.

In this way, the comparators 8 and 9 are used to determine whether the output of the element 1 (its resistance value in the case of a thermistor) in response to the hot air temperature has reached a predetermined value. , 9, respectively. Resistors 11 and 12 and resistors 13 and 14 determine comparison voltages of comparators 8 and 9, respectively.

On the other hand, the operational amplifier 7 compares the standard voltage with the output level of the element 1 and applies a voltage to the photodiode 5 according to the difference in order to keep the hot air temperature constant. In this case, since the output of element 1 is input to the + input terminal and the standard voltage determined by resistors 15 and 16 is input to one input terminal, the larger the difference between the two voltages, the higher the output voltage. In other words, when the temperature is low, such as during ignition, the level of element 1 is low and the difference between the two input voltages to operational amplifier 7 is small, so the output voltage is low, and as steady combustion approaches, the output level of element 1 becomes high. As a result, the difference between the two voltages becomes larger, so the output voltage becomes higher. Since the light emitting output of the photodiode 5 is proportional to the output voltage of the operational amplifier 7, the output of the operational amplifier 7 is ultimately given to the control circuit 3 via the photocoupler 6, and the rotation of the blower fan 2 is controlled in accordance with this voltage. Ru.

Finally, another transistor 22 will be explained. This transistor 22 short-circuits the photodiode 5, and is turned on by the output of the comparator 8 from the time of ignition until it reaches a predetermined temperature.
It turns off when the temperature exceeds a predetermined temperature. The transistor 22 and the comparator 8 constitute blocking means for blocking the operation of the control circuit 3.

In addition, in the figure, r _i (i=1, 2...) is resistance, c _i
(i=1, 2...) is a capacitor, and 23 is a light emitting diode for abnormal overheating alarm.

Then, the operation will be explained. First, when ignited, combustion starts in the combustion section, but at this time, since the temperature near the element 1 is low, the output of the comparator 8 becomes H, and the transistor 22 turns on, shorting the photodiode 5, so the blower fan 2 remains stopped. When combustion continues and the temperature of the combustion part rises, and the ambient temperature of element 1 reaches the first set temperature _t1 shown in FIG. 3, the output level of element 1 exceeds the + side reference voltage of comparator 8 and the comparator The output of transistor 8 becomes L level, turning off transistor 22. At this time, the output of element 1 is compared with the reference voltage corresponding to the standard hot air temperature _t2 by operational amplifier 7, and a voltage corresponding to the difference is output from operational amplifier 7, so photodiode 5
This voltage will be applied to. Therefore,
An output corresponding to this voltage is applied to the control circuit 3 via the photocoupler 6, and the blower fan 2 is driven accordingly. Initially, the temperature of the combustion section, etc. has not risen that much, so naturally the number of revolutions is low. At this time, if the hot air temperature is lower than _t2 , the output level of the element 1 will also be low, the rotation speed of the fan 2 will be reduced, the air volume will be reduced, and the hot air temperature will be naturally raised. Furthermore, when the hot air temperature becomes higher than _t2 , the output level of the element 1 becomes higher, so the rotational speed of the fan 2 increases due to the action of the operational amplifier 7, the air volume increases, and the hot air temperature decreases. In this way, the temperature of the hot air is maintained at approximately t ₂ from the beginning, but the rotation speed of fan 2 increases until the heat generated by combustion and the air volume are balanced and a stable state is reached. remains almost constant.

Next, if the air volume of the blower fan 2 does not increase by more than a certain amount due to filter clogging, etc., and the hot air temperature becomes abnormally high (for example, t ₃ ), the element 1
Since the output level of will also become abnormally high, combustion may be stopped using the output of the comparator 9.

Next, after steady combustion, turn off the operation switch to extinguish the fire. This stops the combustion, but of course the temperature of the hot air does not change immediately after the fire is extinguished. Thereafter, as the combustion section gradually cools down, the operational amplifier 7 lowers the rotational speed of the fan 2 and continues to maintain the hot air temperature at _t2 . However, when element 1 detects a temperature below _t1 , the output of comparator 8 becomes H level, and transistor 2
2 is turned on to stop the rotation of fan 2.

Therefore, the hot air is always constant and there is no feeling of cold air. Moreover, at the beginning of combustion, hot air starts blowing out earlier than in the past (the air volume is small), so the feeling of heating is more comfortable. In addition, even when extinguishing a fire, warm air can be emitted for a long time without giving a feeling of cold air.

As mentioned above, according to the present invention, it is possible to prevent cold air from blowing out at the start of heating. Moreover, hot air can be blown out faster at the start of heating compared to conventional systems.

[Brief explanation of the drawing]

Figure 1: An explanatory diagram showing the relationship between the rotational speed of the fan, the hot air blowing temperature, and the elapsed time in a conventional hot air heater. Figure 2: A circuit diagram of the main parts of the hot air heater of the present invention. Figure 3: An explanatory diagram showing the relationship between the rotation speed of the blower fan, the hot air blowing temperature, and the elapsed time in the present invention. Code, 1: temperature detection element, 2: ventilation fan,
3: Fan control circuit, 6: Photocoupler, 7: Operational amplifier, 8, 9: Comparator, 22: Transistor.

Claims (1)

[Scope of Claim for Utility Model Registration] In a forced convection type heater that sucks indoor air, exchanges heat with a heating source, and blows it out indoors, a temperature sensing element that detects the temperature is installed on the hot air blowing side near the heating source. The output of this temperature detection element is compared with the output corresponding to the standard hot air temperature _t2 , and a control circuit is provided for the blower fan that increases or decreases the rotation speed in accordance with the comparison output. A hot air heater comprising a blocking means for blocking the operation of the control circuit of the blowing fan until the output of the temperature detection element reaches an output corresponding to a blowing start temperature _t1 lower than the standard hot air temperature.