JP2563604B2 - Liquid fuel combustion device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fuel combustion apparatus adapted to supply liquid fuel to a burner section by a pump.

2. Description of the Related Art Generally, in a liquid fuel combustion device, for example, an oil combustor that uses kerosene as a fuel causes an idle operation of a pump caused by a fuel exhaustion
In order to prevent black smoke and soot generated by abnormal combustion that occurs at this time, a fuel detection device that detects the fuel exhaustion is attached to the fuel tank, and when it detects the fuel exhaustion, it outputs the signal and stops the combustion. There is.

In addition, the use environment of oil combustors is not always constant,
When used outdoors, the ambient temperature may change from -20 ℃ to 40 ℃. In such a case, since the viscosity of the fluid changes depending on the temperature, the fuel supply amount by the pump also changes according to the temperature change. At the same time, the amount of combustion air also depends on the temperature change, but the rate of change with respect to the temperature change is different, so that burning in this state results in abnormal combustion.

Therefore, conventionally, whether the amount of combustion air is corrected according to the temperature change and controlled to maintain the optimum combustion conditions,
A method of correcting the drive signal of the pump according to the change in room temperature has been adopted.

An example of the above-described conventional liquid fuel combustion apparatus will be described below with reference to the drawings.

First, in this type of liquid fuel combustion apparatus, as shown in FIG. 4, the liquid fuel in the fuel tank 1 is sucked up by the electromagnetic pump 2 and supplied to the burner unit 3, and the liquid fuel is vaporized by the burner unit 3 and is blown by the fan. It is designed to be mixed with air from No. 4 and burned.

This liquid fuel combustion device is often used in a warm air blower that blows the combustion gas of the burner section 3 as warm air from the blowout port 3a by the fan 4a as shown in FIG. 5, but in this case, fuel exhaustion occurs. And unburned gas, soot, etc. may blow out into the room. Further, in this state, the electromagnetic pump 3 continues to be in an idle state, which causes a problem that the performance thereof deteriorates.

Therefore, generally in this type of liquid fuel combustion apparatus, as shown in FIG. 4, a float switch 5 for detecting the height of the liquid level of the fuel in the tank is attached to the fuel tank 1 separately from the electromagnetic pump 2. Before the electromagnetic pump 2 runs idle due to running out of fuel, the float switch 5 detects running out of fuel and stops the operation of the electromagnetic pump 2.

Further, as a method of preventing abnormal combustion due to a change in ambient temperature, the indoor temperature detecting thermistor 12a provided on the back surface of the fan 4a is used to control the rotational speed of the fan 4 according to the change in the indoor temperature, A method of controlling the drive frequency of the pump 2 to perform temperature correction has been adopted.

However, in the configuration in which the electromagnetic pump 2 and the float switch 5 are separately provided in the fuel tank 1 as described above, the suction port of the electromagnetic pump 2 and the fuel detection unit of the float switch 5 are connected to each other. When the main body of the apparatus is horizontal, the exhaustion of fuel can be detected before the electromagnetic pump 2 runs idle, but the main body of the apparatus is inclined and the electromagnetic pump 2 is located at a position higher than the float switch 5. In this case, the idling of the electromagnetic pump 2 will be faster than the detection of the fuel shortage by the float switch 5, and the above-mentioned problems will occur.

Further, since the electromagnetic pump 2 and the float switch 5 have to be attached to the fuel tank 1 separately, the fuel tank 1 needs a space for attaching these parts. Since a member and a sealing material or the like for preventing liquid fuel from flowing out of the fuel tank 1 are required, the fuel tank 1 cannot be downsized, and the cost is increased due to the large number of parts.

Further, even in combustion correction due to ambient temperature change, if the relationship between the room temperature and the oil temperature is always constant, there is no problem with the conventional correction using the room temperature, but in reality, the relationship between the room temperature and the oil temperature is Since it is constantly changing, there is a problem that performing the operation correction of the fan 4 or the electromagnetic pump 2 only with the room temperature does not provide optimum combustion.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a fuel detection means that reliably detects a fuel exhaustion before the pump runs idle and an optimum combustion that performs combustion correction based on the relationship between the room temperature and the oil temperature, regardless of the inclination of the main body of the apparatus. By using the control means, it is possible to provide a small-sized, inexpensive, highly reliable liquid fuel combustion apparatus in which abnormal combustion does not occur.

Means for Solving the Problems In order to solve the above problems, a liquid fuel combustion apparatus of the present invention includes a burner section that vaporizes and burns liquid fuel, and a pump that sucks fuel in a fuel tank and supplies the fuel to the burner section. A self-heating type thermistor provided above the pump suction part in the pump, an indoor temperature detecting thermistor, and temperature correction setting means for correcting the pump drive signal according to the outputs of the two thermistors, A limiter circuit part for stopping the pump drive signal when the input signal of the self-heating type thermistor exceeds a specified value, and the output signals of the temperature correction setting means and the limiter circuit part are input to respond to a change in oil temperature. The pump drive signal is temperature-corrected and the pump drive circuit controls the operation of the pump by detecting the presence or absence of oil in the fuel tank.

The present invention has the above-described configuration, so that the space required for its installation is reduced, which makes it possible to reduce the size of the fuel tank, which in turn reduces the size of the main body of the device, and reduce the number of parts required for installation and the size of the fuel tank. By doing so, the cost can be reduced. In addition, since the position of the fuel detection unit and the pump are close to each other, it is possible to reliably detect the fuel shortage before the pump runs idle regardless of the inclination of the main body of the device, thereby stopping the drive of the pump. It is possible to prevent abnormal combustion and performance deterioration due to idle operation of the pump.

Also, while the fuel detector is in oil, the oil temperature is detected, the temperature correction value is set by calculating the value of the oil temperature and the value of the room temperature, and input to the drive control circuit of the pump for optimum combustion control. provide.

Example Hereinafter, a liquid fuel combustion apparatus of an example of the present invention,
This will be described with reference to the drawings.

In FIG. 1, 6 is a burner portion for vaporizing and burning liquid fuel, 7 is an oil feed pipe for guiding the liquid fuel to the burner portion 6, 8 is an electromagnetic pump for feeding the liquid fuel to the oil feed pipe 7, and 9 is the burner portion. Combustion fan for supplying combustion air to 6, 10
Is a blower pipe for guiding combustion air from the combustion fan 9 to the burner section 6, 11 is a fuel tank, 12 is the fuel tank 11
Reference numeral 13 is a thermistor, which serves as a fuel detecting means for detecting the presence or absence of the fuel based on the liquid level of the liquid fuel inside, and a fuel detecting means for detecting the fuel temperature.

FIG. 2 is an enlarged cross-sectional view of the electromagnetic pump 8. The thermistor 12 is provided integrally with the suction joint 14, and the mounting position is located above the fuel suction port 15 of the electromagnetic pump 8. There is.

FIG. 3 is a block diagram for controlling the drive of the electromagnetic pump 8 by the thermistor 12. Reference numeral 16 is a limiting resistance for setting the thermistor 12 in a self-heating state, and the fuel detection means A constituted by the resistance 16 and the thermistor 12 detects the presence or absence of fuel in the fuel tank 11 and the temperature of the fuel. Reference numeral 17 is an A / D converter for converting the value of the fuel detecting means A into a digital signal, 18 is an A / D converter for room temperature as above, and 19 is an A / D value of the fuel detecting means A and the room. A differential temperature detection unit for obtaining the differential temperature of the temperature A / D, 20 is an arithmetic circuit unit for setting the correction value of the drive signal of the electromagnetic pump 8 by the value of the differential temperature detection unit 19, and the differential temperature detection unit The section 19 and the arithmetic circuit section 20 constitute a temperature correction setting means B. Reference numeral 21 is a drive circuit for the electromagnetic pump 8, 22 is a limiter circuit section for the A / D value of the fuel detection means A, and when the A / D value exceeds a specified value, a signal is sent to the drive circuit 21 to operate the electromagnetic pump 8. Stop. In other words, when the fuel in the fuel tank 11 decreases and falls below the mounting surface of the thermistor 12, the thermistor 12 is exposed to the air, the heat dissipation constant becomes extremely small, and the self-heating state of the thermistor 12 rapidly increases. The resistance value becomes extremely small. As a result, the limiter circuit unit 22
Detects that the fuel has run out.

Regarding the liquid fuel combustion device configured as described above,
The operation will be described below.

First, if there is more than the specified amount of fuel in the fuel tank 11,
Since the thermistor 12 is immersed in the fuel, its heat dissipation constant is large and the self-heating state of the thermistor 12 is small and stable. In such a state where the self-heating state is small and stable, the heat dissipation constant depends on the temperature of the fuel. Therefore, the value of the fuel detection means A constituted by the resistor 16 and the thermistor 12 is set to the A / D conversion unit 17 Is converted into a digital signal and treated as fuel temperature information. That is, the value of the A / D conversion unit 17 and the room temperature data A / D conversion unit 18 obtained from the room temperature detection thermistor.
The temperature difference is calculated and input to the arithmetic circuit 20 to set an appropriate temperature correction value and input to the electromagnetic pump drive circuit 21. As a result, combustion control becomes possible at room temperature, that is, in a state in which the difference between the combustion air temperature and the fuel temperature is corrected, so that optimal combustion can be provided regardless of any environmental changes.

Next, when the amount of fuel in the fuel tank 11 decreases and the liquid level drops below a specified level, the thermistor 12 is exposed to the air. Therefore, the heat dissipation constant of the thermistor 12 becomes small, self-heating rapidly progresses, and its resistance value becomes extremely small.
As a result, the A / D converted value exceeds the specified value, the limiter circuit section 22 operates, and a stop signal is sent to the electromagnetic pump drive circuit 21 to stop the operation of the electromagnetic pump 8. That is, the fuel shortage is detected.

Further, since the thermistor 12 is integrated with the suction joint 15 of the electromagnetic pump 8, even if the main body of the device is tilted, the thermistor 12 can reliably detect the fuel exhaustion before the electromagnetic pump 8 runs idle. it can.

As described above, according to the present invention, by integrating the pump and the fuel detection means, it is possible to reliably prevent the pump from running dry and abnormal fuel due to running out of fuel, and further to reduce the size of the fuel tank.
As a result, the apparatus body can be downsized, and the cost can be reduced by reducing the number of parts.

Further, by using a self-heating type thermistor for the fuel detection means, it becomes possible to perform combustion control while correcting the difference between the fuel temperature and the combustion air temperature, and it is possible to achieve optimum combustion regardless of any environmental changes. Further, since it is possible to detect the oil surface and the oil temperature with only one self-heating type thermistor, good combustion by the oil surface detection and the oil temperature correction can be realized with a simple configuration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid fuel combustion apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the main part thereof, and FIG.
FIG. 4 is a block diagram in the embodiment of the figure, FIG. 4 is a sectional view of a conventional liquid fuel combustion apparatus, and FIG. 5 is a sectional view of a heater using the liquid fuel combustion apparatus. 6 ... Burner part, 8 ... Electromagnetic pump, 11 ... Fuel tank, 12 ... Self-heating type thermistor (fuel detection means), 12
a …… Indoor temperature detection thermistor, 17,18 …… A / D converter, 21 …… Electromagnetic pump drive circuit, 22 …… Limiter circuit, B …… Temperature correction setting means.

Claims (1)

(57) [Claims] 1. A burner section for vaporizing and burning liquid fuel, a pump for sucking fuel in a fuel tank and supplying it to the burner section, and self-heating provided in the pump above the pump suction section. Type thermistor, room temperature detection thermistor, temperature correction setting means for correcting the pump drive signal according to the outputs of the two thermistors, and pump drive signal when the input signal of the self-heating type thermistor exceeds a specified value. A pump for detecting the presence or absence of oil in the fuel tank by inputting the output signals of the limiter circuit section for stopping the temperature correction setting means and the limiter circuit section, and correcting the temperature of the pump drive signal according to the change in the oil temperature. And a pump drive circuit for controlling the operation of the liquid fuel combustion apparatus.