JPS6315488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion control device for a combustor that detects room temperature and changes the combustion amount steplessly according to the difference between the room temperature and the set value. Even if the difference in temperature is below a certain value or the room temperature becomes higher than the set temperature, combustion is not stopped and the minimum combustion amount is maintained.

Structure of a conventional example and its problems FIG. 1 shows a structural diagram of a combustor composed of a burner whose combustion amount is approximately proportional to the amount of combustion air. 1 is a fuel tank, and fuel 2 in the tank 1 is sucked up by a lamp wick 3 by capillary action. The lamp wick 3 is connected to a lever 4 of a wick up-and-down mechanism, and is normally biased to be located within the fuel tank 1 by the action of a spring 5. 6 is a solenoid that holds the levers 4 above and below the wick 3 in a state in which the wick 3 is pushed upward at the same time as the ignition operation; 7 is a vent cylinder having a vent 8, which serves as a guide for the vertical sliding of the wick 3. 9 is an outer fire pan having a large number of pores 10, 11
is an inner flame cylinder having a large number of primary air supply holes 12. 13 is an outer flame cylinder having a large number of primary air supply holes 14. 15 is the outer cylinder, 16 is the combustion cylinder, 1
7 is a blower fan, 17a is a blower motor, 18 is a wind partition plate having a ventilation hole 19, 20 is a blower guide,
21 is a stand. Reference numeral 22 denotes an exterior case that is placed on the stand 21 so as to cover the combustion section and the blower fan 17, and a suction port 23 is provided near the blower fan 17.
Further, a blower outlet 24 is provided in a portion facing the opening of the blower guide 20 . 25 is a temperature detection element such as a thermistor (hereinafter referred to as room temperature thermistor), which detects the ambient temperature around the device.

It is already known that as a characteristic of the combustor, the amount of combustion and the amount of hot air are approximately proportional to the rotation speed of the fan motor 17a, and this is shown in FIGS. 2 and 3, where a is the temperature of the hot air. , b indicates the amount of hot air, and c indicates the amount of combustion.

FIG. 4 shows a temperature control circuit that controls the amount of combustion in the combustor.

26 is an AC power source that drives the blower motor 17a;
27 is a DC power supply, and AC power supply 26 and DC power supply 27
are connected by bus A. A temperature setting device 28 is connected to the bus line B of the DC power supply 27 via a resistor 29 and to the bus line A via a resistor 30.
Reference numeral 31 denotes a resistor, and a bridge circuit is constituted by a room temperature thermistor 25, a resistor 29, a temperature setting device 28, and a resistor 30. 32 is a differential amplifier, the - input side is connected to the output terminal of the differential amplifier 32 via a resistor 33, and the voltage Va divided by the room temperature thermistor 25 and the resistor 31 is applied via the resistor 34. It has been entered. The + input side is connected to the bus bar A via a resistor 35, while the input side is connected to the temperature setting device 2 via a resistor 36.
It is connected to the movable terminal side of No. 8 and voltage Vb is inputted thereto. A voltage Vo is output from the output terminal of the differential amplifier 32.
is output, and the following equation holds.

Vo=G(Vb-Va) Here, G is the amplification factor and the resistances 33, 34, 35, 36
It is determined by Reference numeral 37 denotes a drive circuit for the blower motor 17a, which is composed of a constant current circuit. That is 37
a is a differential amplifier, 37b is an NPN transistor, and 37c is a resistor. 37d is a smoothing capacitor, and the output of the differential amplifier 37a is adjusted so that the potential generated across the resistor 37c is equal to Vo, and the collector current I of the transistor 37b is constant. A rectifying diode 38 is connected to the blower motor 17a on the anode side and to the transistor 37b on the cathode side, and operates at a rotation speed proportional to the collector current I. 39 is the blower motor 17
This is a diode for applying alternating current to a.

If the room temperature is lower than the set temperature in the above configuration,
Since Vb≫Va, Vo, which is the amplified potential difference between Vb and Va, is also high, a large current flows through the collector of the transistor 37b, and the blower motor 17a rotates at a high rotational speed. Therefore, as shown in FIG. 3, the combustion amount c also increases. The room temperature gradually rises Va
As the potential increases, the potential difference between Vb and Va decreases, so Vo also decreases, and accordingly, the collector current I of the transistor 37b also decreases, causing the rotational speed of the blower motor 17a to decrease. The combustion amount also decreases. However, with the above configuration, when the room temperature becomes equal to or exceeds the set temperature, Vo = O and the blower motor 17a stops, causing an abnormality such as the A/F balance being lost and a large amount of soot being generated. This had the problem of causing combustion and making it impossible to control the combustion.

Purpose of the Invention The present invention has been made in view of the above problems, and when the difference between the room temperature and the set temperature becomes less than a certain value, the output voltage Vo of the differential amplifier 32 is fixed to a certain value, and the blower motor 17a is The purpose is to maintain a state in which combustion control is possible with the minimum amount of combustion by maintaining the minimum rotational speed of the engine.

Structure of the Invention In order to achieve the above object, the present invention always uses Va.
By setting a potential point Va' that is higher than the potential and inserting a diode so that current flows from this potential Va' to Vb, the potential of Vb will always be higher than the potential of Va, so Vo will be kept below a certain value. Therefore, the blower motor 17a is designed to never stop.

DESCRIPTION OF EMBODIMENTS One embodiment will be described below with reference to FIG.
In FIG. 5, parts numbered the same as in FIG. 4 represent the same parts as in FIG. 4. 40 has one end connected to room temperature thermistor 25 and the other end connected to resistor 34 and resistor 3.
The anode side of a diode 41 is connected to the connection point Va' between the room temperature thermistor 25 and the resistor 40, and the cathode side of the diode 41 is connected to the movable terminal side of the temperature setting device.

In the above configuration, the current flows through the room temperature thermistor 25
→ Va' → resistor 40 → Va → resistor 31 → A, so the potential of Va' is always higher than the potential of Va.

If the potential of Vb is higher than the potential of Va', it will be blocked by the diode 41 and no current will flow from Vb to Va', so
Vo is generated and the rotation speed of the blower motor 17a is controlled. As the room temperature rises and the potential of Va′ flows,
Va'=Vb, and the potential of Vb is always higher than the potential of Va by a value determined by the resistor 40. Therefore, Vo will never fall below a certain value and the blower motor 17a will never stop. If the rotational speed of the blower motor 17a at this time is set to be equal to the minimum combustion amount, the appliance will maintain the minimum combustion amount.

Effects of the Invention According to the present invention, even if the room temperature becomes higher than the set temperature with a simple circuit configuration, the blower motor maintains the minimum combustion amount without stopping, thereby preventing abnormal combustion such as generation of yellow flame or soot. This has the effect that a state in which combustion can be controlled can be maintained.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional example, and Figures 2 and 3 are
The figure is a graph showing the same characteristics, Figure 4 is the same circuit diagram,
FIG. 5 is a circuit diagram showing one embodiment of the present invention. 3...Light wick, 17a...Blower motor, 25...Room temperature detection element, 26...AC power supply, 27...DC power supply, 28
...Temperature setting device, 32...Differential amplifier.

Claims (1)

[Claims] 1. A burner whose combustion amount is approximately proportional to the amount of combustion air, a blower mechanism that generates hot air and sucks combustion air using the negative pressure generated by this hot air flow, and detects room temperature. A differential amplifier circuit generates a voltage according to the output difference output from both the temperature detection element and the room temperature setting device, and a motor rotation speed in the blower mechanism is controlled according to the input voltage from the differential amplifier circuit. Equipped with a motor drive circuit that can be varied in stages,
A combustion control device clamped with a diode so that the difference in output from the temperature detection element and the room temperature setting resistor does not fall below a certain value.