JPH0424257Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a combustion device for liquid fuel used for heating purposes, and more particularly to a vaporization type combustion device.

[Prior art] Liquid fuel such as kerosene (hereinafter referred to as fuel) is
A combustion device is known in which the premixed gas is forced into a vaporizer that is heated to a substantially constant temperature by a built-in electric heater, and is ejected from a nozzle to be combusted.

Until now, the mainstream electric heaters mentioned above were those using nichrome wire, but so-called ceramic heaters, which use alumina as a heat-resistant insulating material and embed a tungsten heating element in it, have been put into practical use, and even heat-resistant Silicon nitride is also being used as an insulating material.

The ceramic type electric heater described above has many superior features compared to conventional nichrome wire heaters. In other words, there is a small difference in thermal expansion coefficient between the tungsten heating element and the heat-resistant insulating materials such as alumina and silicon nitride in which it is embedded, making it difficult for damage due to thermal strain to occur even if the temperature changes rapidly. has a small resistance value in the low temperature range, and because it consumes an extremely large amount of power at the initial stage of energization, it is possible to raise the temperature of the vaporizer in a short time.Furthermore, the watt density of the tungsten heating element is lower than that of nichrome wire. Since it is large, the electric heater can be made compact and lightweight, and this has many practical advantages, such as making the vaporizer compact and lightweight and shortening the preheating time.
However, while these advantages are available,
Problems also occur.

This problem will be explained below with the help of figures.

FIG. 1 is a schematic configuration diagram of a conventional liquid fuel combustion apparatus, and FIG. 2 is a cross-sectional view taken along line A-A' in FIG.
In the figure, when the power is turned on, electric heater 1
Since the tungsten heating element 2 is energized,
The temperature of the vaporizer 3 increases rapidly. When the vaporizer temperature detected by thermistor 4 reaches a temperature sufficient to vaporize the fuel, solenoid 5
is energized, and when the valve rod 6 slides against the bias of the spring 7, the needle valve 8 separates from the nozzle pipe 7, the nozzle 9 opens, and the electromagnetic pump 1
0 also starts. Therefore, the fuel in the tank 11 is pressure-fed to the vaporizer 3, where it is heated and vaporized to become vaporized gas.
After flowing into the nozzle pipe 7 through the communication port 12, it is ejected from the nozzle 9 into the burner 13, and is ignited by the ignition device 14 to start combustion.

And the vaporizer temperature during combustion is the vaporizer 3
It is desirable to maintain a substantially constant temperature even if the amount and temperature of the fuel flowing into the fuel tank or the outside air temperature change. Therefore, the energization to the tungsten heating element 2 is often controlled to be turned on or off based on the vaporizer temperature. Figure 3 shows the fluctuation in vaporizer temperature due to this control. When the temperature rises to point A, the electricity is turned off, and when the temperature falls to point B, it is turned on.
By doing so, a substantially constant temperature, that is, a range of A to B is approximately maintained.

However, since the thermistor 4 is installed at a location slightly apart from the electric heater 1 and its vicinity, the vaporizer temperature is detected with a delay. Therefore, the inside of the vaporizer 3 at point A is greatly overshot, and the thermistor 4 also rises in temperature due to the residual heat, resulting in peak A. Similarly, after reaching point B, the temperature is undershot. Peak B occurs. And this overshoot etc. is a ceramic type electric heater 1
This is particularly noticeable in the vaporizer 3, where the temperature rises and falls rapidly. Therefore, the vaporized gas at an appropriate temperature and pressure is periodically supplied to the burner 13.
There was a drawback that the combustion condition worsened as the fuel was not supplied to the carburetor 3, and a large amount of carbon, tar, etc. were generated, shortening the life of the carburetor 3.

To solve this problem, tungsten heating element 2
There is also a method of controlling the supply of electricity to the device by phase control, but the periodic sudden changes in power generate noise, which has an adverse effect on other electrical appliances that share the same power source.

[Problems to be Solved] In the circumstances described above, the present invention provides a liquid fuel combustion method that reduces fluctuations in vaporizer temperature during operation, maintains good combustion, and extends the life of the vaporizer. It is intended to obtain equipment.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses an electromagnetic pump to pressure feed fuel into a vaporizer heated to a substantially constant temperature by a built-in electric heater, vaporizes the fuel, and vaporizes the fuel. In a liquid fuel combustion device that injects fuel into a burner from a nozzle that opens at the tip of a nozzle pipe that communicates with a vaporizer through a communication port and burns it, multiple tungsten heating elements are embedded integrally in a heat-resistant insulating material such as silicon nitride or alumina. During combustion, some of the tungsten heating elements are continuously energized, and the remaining tungsten heating elements are energized by ON/OFF control.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. Components that are the same as those explained in FIGS. 1 and 2 are given the same numbers, and detailed explanations will be omitted.

In the main part sectional view of FIG. 4, the difference from the conventional method is that the electric heater 1 is formed by embedding, for example, two tungsten heating elements 16 and 17 having the same calorific value in a heat-resistant insulating material 15. Furthermore, the total calorific value of the tungsten heating elements 16 and 17 is set here to be approximately the same as that of the conventional tungsten heating element 2.

When maintaining the vaporizer temperature at a substantially constant temperature with such an electric heater 1, one tungsten heating element 16 is continuously energized, and the other tungsten heating element 17 is energized by ON/OFF control. To explain the fluctuation of the vaporizer temperature due to this control using FIG. 5, when point A is reached, the tungsten heating element 1
7 is turned off and the amount of heat generated is halved, so the vaporizer temperature rises a little and then begins to drop slowly. Since the temperature distribution of the vaporizer 3 during the downward movement is small, the temperature of the vaporizer 3 starts to rise with almost no undershoot even when the current is turned on after reaching point B. Furthermore, if undershoot is prevented, the detection delay of the thermistor 4 will be reduced when point A is reached again, so overshoot will also be reduced. Therefore, the vaporizer temperature is kept at a substantially constant temperature, and the temperature and ejection pressure of the vaporized gas are stabilized, allowing good combustion to be maintained, and the amount of carbon, tar, etc. generated is reduced, extending the life of the vaporizer 3. It will become.

Furthermore, although this embodiment has been explained using an electric heater using two tungsten heating elements, two or more electric heaters may be buried, and in this case, overshoot etc. can be further reduced. Needless to say.

[Effects of the invention] As explained above, the liquid fuel combustion device of the invention has an electric heater built in the vaporizer, which is formed by embedding a plurality of tungsten heating elements in a heat-resistant insulating material, and also The structure is such that some of the tungsten heating elements are continuously energized, and the remaining tungsten heating elements are energized by ON/OFF control, so the vaporizer temperature changes gradually and undershoot can be prevented. This reduces overshoot, keeps the overall carburetor temperature at a constant temperature, maintains good combustion, and reduces the amount of tar and carbon generated, extending the life of the carburetor. It has practical effects.

[Brief explanation of drawings]

Figures 1 and 2 are schematic configuration diagrams of a conventional liquid fuel combustion device, Figure 3 is a diagram illustrating temperature changes in a conventional vaporizer, and Figure 4 is a sectional view of essential parts of the liquid fuel combustion device of the present invention. , FIG. 5 is a diagram illustrating the temperature change of the vaporizer according to the present invention. 1... Electric heater, 3... Vaporizer, 7... Nozzle pipe, 9... Nozzle, 10... Electromagnetic pump, 1
2...Communication port, 13...Burner, 15...Heat-resistant insulating material, 16, 17...Tungsten heating element.

Claims (1)

[Scope of utility model registration request] An electromagnetic pump pumps fuel into the vaporizer, which is heated to a constant temperature by a built-in electric heater, vaporizes it, and then squirts it into the burner through a nozzle that opens at the tip of a nozzle tube that communicates with the vaporizer through a communication port. In a liquid fuel combustion device that burns tungsten heating elements, an electric heater is formed by embedding multiple tungsten heating elements in a heat-resistant insulating material such as silicon nitride or alumina, and some of the tungsten heating elements are continuously energized during combustion. , the remaining tungsten heating element is
A liquid fuel combustion device characterized by applying electricity through ON/OFF control.