JPH0473046B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to liquid fuel combustion devices such as kerosene stoves,
Especially when teaching about liquid fuel combustion equipment using a synchronized gasification burner, which has the characteristic that the air-to-air ratio, that is, the ratio between the amount of combustion air and the amount of combustion oil, remains almost the same without being affected by changes in the amount of combustion. The present invention relates to a structure that can improve ignition characteristics.

(Prior Art) Many devices have been proposed in the past that can automatically perform a series of operations for preheating, ignition, and blowing hot air upon completion of ignition in liquid fuel combustion devices, such as hot air heaters that use kerosene as fuel. It has been published in Japanese Unexamined Patent Publication No. 122821/1986.
There are some well-known devices such as No. 1, which incorporate various measures to improve the stability of automatic ignition.

For example, the method disclosed in the above-mentioned publication changes the amount of oil fed while operating the air blowing mechanism and oil feeding mechanism in the same way as during steady operation, thereby reducing the air-to-air ratio at the start of combustion operation. For example, by increasing the proportion of the amount of fuel oil, an oil-rich ignition method is adopted and stable ignition is achieved.

(Problems to be Solved by the Invention) The above-mentioned known device has a structure in which the amount of oil fed by the oil feeding mechanism can be adjusted independently of the air blowing mechanism, so an oil-rich ignition system can be easily adopted. However, there is a synchronized gasification burner (structure) that has a structure in which an arbitrary combustion amount can be obtained by changing the rotation of the drive motor while keeping the air-to-air ratio at approximately the same value in the steady operation range. In the case of a liquid fuel combustion device using a synchro gasification burner (which will be described in detail later), there is a problem that the oil-chip ignition method cannot be easily performed. Unless this point is also improved, ignition stability will not be achieved.

That is, the synchro gasification burner has the structure shown in FIG. 4, and the preheating electric heater 29 of the vaporizer 28 is energized by operation.
When the temperature of the vaporizer 28 increases and reaches a certain temperature, the ignition is activated by a command from a temperature sensor that detects this temperature. In this case, as shown in the diagram shown in FIG. A considerably large temperature drop (ΔT) occurs between the vessel 28 and the burner nozzle 32 due to the difference in the degree of gradual temperature rise.

This is due to the fact that the temperature of the vaporizer 28 increases rapidly during the process in which the heat of the vaporizer 28 is transferred to the burner flame port 32.

When the temperature difference (△T) becomes large in this way, the fuel vaporized in the vaporizer 28 flows into the burner flame port 32.
It is therefore difficult to achieve the best ignition conditions.

Particularly in the case of low-temperature ignition operation in extremely cold weather, fuel vapor vaporized in the carburetor 28 may condense at the burner nozzle 32, resulting in poor ignition.

In addition, since the synchronized gasification burner 3 sets the air-to-air ratio based on the conditions during steady operation, the air density is high during such low-temperature ignition, resulting in a slight excess of air, which may cause lift combustion to occur. In low-temperature atmospheres, combustion often occurs in low-temperature atmospheres, such as when something ignites but quickly goes out.

As described above, the present invention has been made in view of the fact that it is difficult for synchro gasification burners to easily adopt an oil-rich ignition system, and furthermore, there is a problem of unstable ignition performance at low temperatures. At the start of combustion operation, when the temperature of the vaporizer rises, the motor of the synchro gasification burner is pre-rotated at a slow speed, and then the motor rotation speed is controlled so that it switches to high-speed operation at the same time as ignition. Then,
The purpose is to improve ignition characteristics and heating start-up characteristics.

(Means for Solving the Problems) As is clear from the accompanying drawings, the present invention provides a fuel oil pump 14 and a combustion air fan 2.
7 is connected to a variable speed motor 12 so that it can be integrally driven, and by changing the speed of the motor 12, a synchronized gasification burner 3 is constructed such that an arbitrary combustion amount can be obtained with substantially the same air-to-air ratio. The motor 12 is operated at a slow speed to the extent that the fuel oil pump 14 does not cause an oil feeding action in the latter half of the preheating period immediately before the ignition operation at the start of the combustion operation. Then, the motor 12 is raised to a high speed higher than the speed in the steady operating range at the same time as confirmation of ignition operation.
The present invention is characterized in that it is equipped with a motor control means 9 that increases the speed of the motor and maintains the speed until the heating air starts when the ignition is completed, and then switches the speed to the speed during steady operation.

(Function) The present invention operates the motor 12 at a slow speed, for example, during the latter half of the preheating period immediately before the ignition operation at the start of the combustion operation, that is, from the time when the carburetor 28 reaches a predetermined temperature, for example, 250°C, until immediately before the ignition operation.
By rotating at 500 rpm, air is blown by the fan 27 without sending fuel oil, and as a result, air convection occurs within the burner 3, the temperature of the burner flame port 32 rises, and ignition becomes easier.

Then, by increasing the speed of the motor 12 to a high speed at the same time as confirming the ignition operation, the burner nozzle 3
In situations where the temperature is high, it is possible to maintain an oil-rich state by lowering the air-to-air ratio below the value within the steady operating range, achieving stable combustion during low-temperature operation, and also speeding up the heating start-up time. Is possible.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIGS. 2 and 3 are schematic structural diagrams of kerosene-fired warm air fans according to each example of the device of the present invention, and show an air intake port 6 equipped with an air filter and an air outlet provided with a wind direction changing blade. A convection fan 2, a synchro gasification burner (hereinafter abbreviated as burner) 3, a combustion chamber 4, and a heat exchanger 5 are housed in the casing 1 having a casing 7 in the order listed from below.
The illustrated example uses indoor air as combustion air,
Furthermore, this is a so-called oil fan heater in which the exhaust gas is discharged indoors or outdoors through a chimney.On the other hand, the example shown in FIG. This type of hot air blower uses outdoor air as combustion air and exhausts exhaust gas outdoors. In both figures, 10 is a room temperature detection thermistor placed near the air intake port 6.

Both of the hot air blowers are equipped with a burner 3 and a motor control means 9 having the same structure, which will be explained sequentially with reference to FIG. 4 and FIG. 1.

The burner 3 has a structure in which the capacity can be changed steplessly from the lowest to the highest in the steady state of operation, and 11 is a housing, and 12 is disposed in the center of the housing 11 with a drive shaft 13 in the vertical (vertical) direction. The drive motor is variable speed; the example shown is a double-shaft motor,
Reference numeral 14 denotes a fuel oil pump that is disposed below the double-shaft motor 12 and is driven by the motor 12.

The fuel oil pump 14 has a pump chamber 17 into which fuel oil is supplied through an oil supply port 16 in a pump receiver 15, and the pump chamber 17 has a center hole through which the drive shaft 13 passes. Partition plate 18 having
There are formed an oil reservoir chamber 17a which is divided into upper and lower parts by an oil reservoir chamber 17a and communicates with the oil supply port 16, and a rotor chamber 17b which communicates with the oil reservoir chamber 17a through the center hole of the partition plate 18. The lower end of the drive shaft 13 of the double-shaft motor 12 extends to 17b, and an oil rotor 19 is fixed to the lower end of the drive shaft 13, and rotates with the rotation of the drive shaft 13 of the double-shaft motor 12. The oil rotor 19 is configured to suck oil from the oil reservoir chamber 17a into the lower part of the rotor chamber 17b, and discharge it from the lower part of the rotor chamber 17b through an oil supply passage 20, which will be described later.

Furthermore, the upper end of the drive shaft 13 of the double-shaft motor 12 extends to the center of the carburetor 28, which will be described later, and an oil supply passage 20 is formed in the center of the drive shaft 13. The lower end of the oil supply passage 20 is connected to the rotor chamber 17b through the nozzle 21.
is communicated with.

On the other hand, an oil supply passage 2 is provided at the upper end of the drive shaft 13.
A post member 23 having a vertical communication path 22 that communicates with the upper end of the boss member 23 and the drive shaft 1
The boss member 23 has a plurality of horizontal discharge ports that communicate with the upper end of the communication path 22 and open in the radial direction (horizontal direction). 25, 25 are bored, and a diffusion blade 2 is provided on the outer periphery of the upper end of the boss member 23.
6 is installed.

By having such a structure, the oil from the pump 14 is discharged horizontally from each of the horizontal discharge ports 25, 25 via the oil supply passage 20 and the communication passage 22, and the discharged oil is transferred to the diffusion plate 24. and diffused by the diffusion vane 26 and atomized to the vaporizer 28.
It will be supplied internally.

Next, reference numeral 27 is a combustion air fan fixed to and driven by the upper part of the drive shaft 13 of the double-shaft motor 12, and 28 is arranged at a predetermined distance above (downstream) of the fan to vaporize fuel oil. A preheating air heater 29 is disposed on the outer periphery of the vaporizer 28 to heat the vaporization to promote vaporization. A vaporizer tube 31 having a conical head shape is provided, and a burner flame port 32 formed of a wire mesh tube is provided concentrically on the outside of the vaporizer tube 31, while a gap is provided near the burner flame port 32. A facing electrode plug 33 for ignition is arranged, and the carburetor 2
The fuel oil supplied to the fuel oil tank 8 and vaporized here is mixed with the combustion air taken in by the combustion air fan 27 from the intake port 34 opened in the housing 11, and the gaseous fuel thus obtained is fed into the burner. flame mouth 3
At step 2, the discharge arc from the electrode plug 33 ignites and burns the fuel.

In addition, 35 is a flame sensor provided at a position where it can come into contact with the flame ejected from the flame outlet of the burner flame port 32 to confirm the ignition state, and 36 is a flame sensor of the vaporizer 28 to detect the vaporization temperature of the fuel oil. This is a burner temperature detection thermistor mounted on the wall.

Although the motor control means 9 is shown as a block in FIG.
a current detection circuit 45 that detects and amplifies when the ignition is detected by a change in current in step 2;
A flame detector 40 comprising a comparison circuit 46 that compares the output current of this current detection circuit 45 with a set value and outputs an "H" signal indicating that ignition has occurred, detects the vaporization temperature of the vaporizer 28. A temperature detection circuit 47 that amplifies the current change caused by the resistance change of the burner temperature detection thermistor 36 compares the output current of this temperature detection circuit 47 with a set value to determine that the temperature of the vaporizer 28 has reached the set temperature. A burner temperature detector 41 consisting of a comparator circuit 48 that outputs an "H" signal, a temperature detection circuit 49 that amplifies current changes due to resistance changes of the room temperature detection thermistor 10 that detects room temperature, and an output current of this temperature detection circuit 49. A room temperature detector 4 comprising a comparison circuit 50 that compares the room temperature with a set value and outputs an "H" signal indicating that the room temperature is lower than the set value.
2. Each of the detectors 40 is composed of a logic circuit;
An operation mode command circuit 43 operates in response to signals from 41 and 42 and issues an operation mode command, and an operation mode command circuit 43 operates in response to the operation mode command of this command circuit 43 and outputs speed reduction or speed increase to the motor 12. The output circuit 44 is composed of five elements, and its operating mode will be explained below with reference to the time chart in FIG. 5 and the characteristic diagrams in FIGS. 6 to 11.

At the same time as the start of operation, the preheating electric motor 29 is energized, and as the temperature of the vaporizer 28 rises, the temperature at the burner flame opening 32 gradually rises at a low value as a result of heat conduction by natural convection.

At this time, the temperature increase state of the burner flame port 32 and the resistance value change state of the burner temperature detection thermistor 36 attached to the vaporizer 28 are as shown in FIGS. 7 and 8.

When the temperature of the burner flame port 32 reaches point P in FIG. 7 (approximately 200° C.) in the middle of the preheating time by the electric heater 29, the “H” signal transmitted from the burner temperature detector 41 The operation mode command circuit 43 is activated, causing the double-shaft motor 12 to operate at a very low speed, for example.
A command is issued to drive at 500rpm.

Since the double-shaft motor 12 thus rotates at a slow speed, the combustion air fan 27 starts blowing a small amount of air, and as a result of the forced convection, the heat of the vaporizer 28 is transferred to the burner nozzle 32, and as a result, both 28, 32
The temperature difference (△T) between them will shrink.

It goes without saying that the oil feeding action of the pump does not occur during this slow rotation.

During the steam preheating period, the temperature rise state in the vaporizer 28 and the burner flame port 32 is as shown in FIG.
Conventionally, heat transfer from the vaporizer 28 to the burner flame port 32 was based on heat conduction and natural convection, and there was a considerably large temperature difference (△T), but by making this a forced convection, (Δt), and the ignition conditions can be improved.

On the other hand, the relationship between the rotation of the double-shaft motor 12 in the burner 3, the oil volume of the pump 14, and the air volume of the fan 27 is shown in FIG. The oil supply function is not performed and oil is not sprayed into the vaporizer 28, and only the ventilation function is performed at a low air volume.

Note that oil spray does not occur in the steam slow operation zone, as shown in the structure of the burner 3 in FIG.
This is due to the relationship between the head difference up to 5 and the push-up force.

As the preheating time period elapses, the temperature of the burner nozzle 32 rises to approximately 240°C, and when preheating is fully achieved, the electrode plug 33 is activated by an ignition command signal from the sequence control circuit. High voltage is applied and ignition is activated.

This ignition occurs instantaneously, and when the flame detector 40 confirms that the ignition has occurred by outputting an "H" signal, a speed increase command is sent from the operation mode command circuit 43, and thus the double-shaft motor 12 is operated at a steady state. The vehicle is operated by switching to a maximum speed higher than the speed within the operating range (see FIGS. 6 to 8).

As a result, the air volume of forced convection increases, and
Since a large amount of oil is sprayed in the vaporizer 28, the vaporized fuel is ignited at the burner flame port 32.

As shown in Fig. 6, this increased speed operation after ignition confirmation is in the operating region where the oil-rich condition is satisfied compared to the case of steady operation regarding the air-fuel ratio, so stable combustion can be obtained during constant temperature operation. .

In this way, the stable combustion state is reliably maintained, for example, after approximately one minute has elapsed from the start of ignition, and at this point, the convection fan 2 is driven at high speed, and at the same time,
The combustion operation start is completed by decelerating the double-shaft motor 12 during steady operation, for example, by switching to a high speed.

Thereafter, the convection fan 2 and the double-shaft motor 12 are automatically switched between high speed and low speed based on the output of the room temperature detector 42, and heating operation is performed to maintain the room temperature constant.

The operating conditions described above are as shown in FIGS. 5 and 10.

In this way, it is possible to operate the double-shaft motor 12 at a slow speed and preheat the burner nozzle 32 sufficiently before starting high-speed operation to ensure reliable ignition using the high-speed oil-rich method. In practice, considering that operating the double-shaft motor 12 at high speed increases the operating noise, such speed switching is performed by the room temperature detector 42 only at the time of startup when the intake air is low. Preferably, a prohibition circuit is provided to prevent operation at high speeds. Further, the present invention is particularly effective when used in the FF warm air fan shown in FIG.

(Effects of the Invention) Next, the effects of the present invention will be described as follows.

(a) During combustion operation, forced convection is performed in the first half of the preheating period to reduce the temperature difference between the vaporizer 28 and the burner flame port 32 to maintain conditions for easy ignition, and in the second half, an oil rich method is used. Since ignition is performed, ignition is reliably achieved, there is no problem of ignition failure even at low temperatures, and ignition characteristics are improved.

(b) Since the air flow and oil volume are controlled to be increased at the ignition timing, the heating start-up characteristics at the time of startup are improved, which has a great effect on creating a comfortable environment.

[Brief explanation of the drawing]

FIG. 1 is an electric control circuit diagram according to an embodiment of the present invention, FIGS. 2 and 3 are schematic structural diagrams of each example of the present invention, and FIG. 4 is a mechanical diagram of a burner used in both of the above examples. FIG. 5 is a time chart at the start of combustion operation according to the present invention, FIGS. 6 to 10 are characteristic diagrams of the device of the present invention, and FIG. 11 is a characteristic diagram of a conventional liquid fuel combustion device. be. 3... Synchro gasification burner, 9... Motor control means, 12... Motor, 14... Fuel oil pump, 27... Combustion air fan.

Claims (1)

[Claims] 1 Fuel oil pump 14 and combustion air fan 27
and a synchro gasification burner 3 connected to a variable speed motor 12 so that they can be integrally driven, and by changing the speed of the motor 12, an arbitrary combustion amount can be obtained with almost the same air-fuel ratio. In the fuel combustion apparatus, in the second half of the preheating period immediately before the ignition operation at the start of combustion operation, the motor 12 is operated at a slow speed to the extent that the fuel oil pump 14 does not produce an oil feeding action to perform an air blowing action. Then, at the same time as confirming the ignition operation, the speed of the motor 12 is increased to a high speed higher than the speed in the steady operation range, and after continuing until the ignition is completed and hot air starts to be sent, the speed at the time of steady operation is increased. A liquid fuel combustion device characterized in that it is equipped with a motor control means 9 that switches to the motor control means 9.