JPS63156917A - Liquid fuel burner - Google Patents

Abstract

PURPOSE:To prevent overchuting and to improve the ignitability and safety of the burner by outputting a combustion starting command when integrating power applied to an electric heater reaches a predetermined value at the time of starting the operation or the temperature of an evaporator reaches a predetermined value, in the liquid fuel burner for space heating or the like. CONSTITUTION:When an operating switch 18 is turned ON, power supply to the heating element 14 of an electric heater is started. A power integrating circuit 20 carries out a power integration by a current detected by a current detection circuit 19 and a voltage detected by a voltage detection circuit 21. The result of the integration is supplied to a control circuit 22. On the other hand, a temperature sensor 15 detects the temperature of a carburetter. When the inputted integrating power reaches a set power quantity or the temperature of the evaporator reaches a preset value, the control circuit 22 commands the combustion starting action. By this construction, overchuting is prevented and the ignitability and stability of the combustion can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustion device for liquid fuel used for heating purposes, etc., and more particularly to one that preheats a vaporizer to vaporize fuel and then combusts it.

[Prior Art] A device is known in which a liquid fuel such as kerosene is turned into a vaporized gas by a vaporizer heated by an electric heater, and the vaporized gas is guided to a burner and combusted.

Up until now, the mainstream electric heaters used in the vaporizers of such devices have been those using nichrome wire, but so-called ceramic heaters use alumina as a heat-resistant insulating material and embed a tungsten heating element in it. has already been put into practical use, and electric heaters using silicon nitride as a heat-resistant insulating material are also being put into practice.

These ceramic heaters have many superior features compared to conventional heaters using nichrome wire.

First of all, there is little difference in the coefficient of thermal expansion between tungsten, which is the two heating elements, and alumina or silicon nitride, which is the insulating heat-resistant material in which it is buried, and it is difficult to imagine damage due to thermal strain even if there is a sudden temperature change. In addition, the tungsten heating element has an extremely large change in electrical resistance due to temperature, and its resistance is small in a low temperature range, so it can generate extremely high power when energized and raise the temperature of the vaporizer in a short time. Furthermore, the watt density of the tungsten heating element is higher than that of a heating element made of nichrome wire, which allows the electric heater to be made smaller and lighter.The vaporizer that incorporates this element can also be designed to be smaller and lighter, reducing the preheating time. Ceramic heaters have many practical advantages, such as shortening the length and good followability of temperature control. However, while these advantages are 9, there can also be some disadvantages.

This will be explained below according to Figure 9.

Fig. 1 is a schematic configuration diagram showing one embodiment of the liquid fuel combustion device according to the present invention, and Fig. 2 is a cross-sectional view taken along the line A-A' in Fig. 1. The fuel in the tank (
5), goes up the nozzle pipe (6), is guided to the nozzle (7), is ejected toward the burner (8), and is ignited and burned at the crater (9).

In addition, (lO) is a valve rod, and the tip of the nozzle (7) is closed by the bias of a spring (11) during stoppage and preheating, and is closed by the electromagnetic force of a solenoid (12) during operation. The needle valve (1) overcomes the bias of the spring (11) and opens the nozzle.
3).

When the power is turned on to operate the present combustion apparatus, the heating element (14) of the electric heater (4) is simultaneously energized. This causes the electric heater (4) to generate heat and raise the temperature of the vaporizer (3). The temperature of the vaporizer (3) is detected by the temperature sensor (15) attached to the vaporizer (3), and the temperature of the vaporizer (3) has reached a temperature sufficient to vaporize the fuel due to preheating. The control circuit detects a change in the resistance value of the temperature sensor (15) and determines whether or not the temperature sensor (15) has been used. After determining that the vaporizer (3) has reached a sufficient temperature, the control circuit energizes and drives the oil pump (2), energizes the solenoid (12), and ignites the burner nozzle (9). The devices (16) are commanded to operate almost simultaneously, and combustion continues thereafter. Note that (17) is a return valve for releasing the pressure of the vaporized fuel during preheating to the tank (1), and like the solenoid (12), it is energized during combustion and is configured to block the return path (18) at this time. has been done.

[Problems to be solved] As mentioned above, in conventional liquid fuel combustion devices,
The completion of preheating of the vaporizer (3) is determined by the temperature sensor (15).
) reached a sufficient temperature. The temperature sensor (I5) is installed in a location that is slightly away from the electric heater (4) and the surrounding vaporizing part, so that the inside of the vaporizer (3) is sufficiently raised when the heating element (14) is energized. Since the temperature sensor (15) detects this with a delay even if it is warmed up, there is a possibility that the inside has reached an overheating state when the temperature sensor (15) reaches the temperature at which preheating is determined to be complete.

In other words, this temperature delay, which was not a problem in practice with conventional nichrome wire heaters, which have a slow temperature rise, can be overcome by ceramic heaters, which are smaller, lighter, and generate more heat than nichrome wire heaters. - temperature sensor (15
) temperature detection cannot follow this change, which causes overshoot. If the fuel oil deviates from the appropriate vaporization temperature, it will not be possible to supply vaporized gas at the normal temperature and pressure to the burner (8), resulting in poor ignitability and stability of combustion immediately after ignition, as well as carbon buildup inside the vaporizer. ,
This is undesirable as it causes the generation of tar and shortens the life of the vaporizer.

In order to solve this problem, it is possible to configure the control circuit so that the temperature sensor (15) issues an ignition command early before it reaches a sufficient vaporization temperature, but if the combustion device is left indoors for a long time, Even if it is effective when the conditions are constant, such as when the operation is started after the combustion has been completed, operation may be temporarily interrupted during combustion and the operation may be started when the temperature of the vaporizer (3) has not yet fallen to room temperature. It is clear that if the vaporizer were restarted, ignition would occur without the temperature inside the vaporizer being able to match the target temperature.

[Means for Solving the Problems] In the circumstances as described above, two aspects of the present invention prevent the overshoot of the vaporizer temperature at the start of combustion.

The purpose is to start combustion at the optimum vaporization temperature, improve ignitability and stability of combustion immediately after ignition, and extend the life of the vaporizer.

In order to achieve the above object, the liquid fuel combustion apparatus of the present invention is operated by a temperature sensor attached to the vaporizer, or when the integrated amount of electric power applied to the electric heater of the vaporizer reaches a predetermined value at the start of operation. When it is determined that the temperature of the vaporizing device has risen to a predetermined temperature based on the signal value from the circuit, combustion is performed based on a command from the circuit when one of the conditions is satisfied. In other words, this invention provides a liquid fuel combustion apparatus in which liquid fuel is supplied to a vaporizer heated by an electric heater and vaporized, and the vaporized gas is combusted by a burner.
Calculate the integrated amount of power applied to the electric heater,
a circuit configured to issue a command to perform a combustion start operation when the integrated electric energy reaches a predetermined value;
It has a circuit configured to issue a command to start combustion when a signal value from a temperature sensor attached to the vaporizer reaches a value corresponding to a predetermined temperature, and at least one of the This is a liquid fuel combustion device characterized in that it is configured so that a combustion start operation is performed in response to a command from a circuit.

[Example] An example of the configuration of the liquid fuel combustion apparatus of the present invention is shown as a circuit configuration in FIG. The power supply to the heating element (14) of the electric heater (4) provided in the device (3) is started, and at the same time, the integration of electric power is started. Power integration is performed in the following steps. First, a power detection circuit (19) detects the current flowing through the heating element (14) and outputs it to the power integration circuit (20). Power integration circuit (2
At the same time, the voltage applied to the heating element detected by the voltage detection circuit (21) is input to 0).

Here, the current and voltage are multiplied and output as electric power to the control circuit (22). In the control circuit (22), the electric power is integrated immediately after the operation switch (18) starts energizing the circuit, and when the total integrated electric energy reaches a predetermined electric energy, combustion starts. A directive is issued to carry out the

On the other hand, the temperature signal from the temperature sensor (15) attached to the vaporizer (3) is also sent to the control circuit (22), so the control circuit (22) uses the temperature signal to preset the vaporizer (3). Once it confirms that the predetermined temperature has been reached, it also issues a command to start combustion.

This combustion start operation is performed if either the integrated power amount or temperature detection condition is satisfied.

The predetermined value of the integrated electric energy and the temperature are determined by changing the operation switch (18
) is turned on, it is determined on the premise that the combustion start operation will be performed according to a command from the integrated power side. However, the operation was temporarily stopped in the middle of combustion, and the vaporizer (3
) restarts operation and reheats the vaporizer (3) when the temperature does not drop to room temperature, the vaporizer (3) temperature reaches the set temperature before reaching the specified integrated power consumption. There is also a possibility that combustion will be restarted based on the temperature signal from the temperature sensor (15).

Of course, when determining whether to restart combustion using the temperature sensor (15), it is impossible to match the actual temperature inside the vaporizer (3) with the temperature of the temperature sensor (15). When the heater is energized from a relatively high temperature, it does not generate heat rapidly, and the temperature difference between the temperature sensor (15) and the inside of the vaporizer (3) is suppressed to a level that does not cause any practical problems. It will be done.

[Effects of the Invention] As described above, the liquid fuel combustion device according to the present invention calculates the cumulative amount of power applied to the electric heater at the start of operation, and starts combustion when the predetermined cumulative amount of power is reached. A circuit configured to issue a command to perform the operation, and a command to perform the combustion start operation when the signal value from the temperature sensor attached to the vaporizer reaches a value corresponding to a predetermined temperature. It has a circuit configured to emit a By determining whether the preheating of the vaporizer is completed when the vaporizer is added, combustion will start when the temperature inside the vaporizer reaches the optimal condition, even if the power supply voltage fluctuates or the resistance value of the heating element changes due to long-term use. Operation can be commanded and there is little overshoot.

In addition, if operation is temporarily interrupted during combustion and restarted when the vaporizer has not cooled down sufficiently,
Since the combustion start operation can be performed by the function of the temperature sensor, there is no need to worry about overheating of the vaporizer, unlike when issuing a combustion start command using only the integrated electric energy, and the ignition performance and combustion stability immediately after ignition are improved. At the same time, the durability of the vaporizer can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a liquid fuel combustion apparatus according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA' in FIG. Also,
FIG. 3 is a circuit diagram of the liquid fuel combustion device of the present invention. 3... Vaporizer, 4... Electric heater, +4... Heating element, 15... Temperature sensor. Patent applicant: Dainichi Kogyo Co., Ltd. Representative: Fumio Sasaki, R1

Claims (1)

[Claims] In a liquid fuel combustion device that supplies liquid fuel to a vaporizer heated by an electric heater, vaporizes it, and combusts this vaporized gas with a burner, calculate the integrated amount of electricity applied to the electric heater at the start of operation. , a circuit configured to issue a command to perform a combustion start operation when the integrated electric energy reaches a predetermined value, and a signal value from a temperature sensor attached to the vaporizer to reach a predetermined temperature. The combustion start operation is characterized by having a circuit configured to issue a command to perform a combustion start operation when a value corresponding to the value is reached, and the combustion start operation is performed by a command from at least one of the circuits. Liquid fuel combustion equipment.