JP2002022154A - Liquid fuel combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid fuel combustion device capable of effectively preventing the lift and blow-off of flame by lowering an air-fuel ratio to perform ignition at the time of cold start-up. SOLUTION: A liquid fuel combustion device 10 comprises a combustion part 14, an electromagnetic pump 18 feeding liquid fuel to the combustion part 14, a blower 19 supplying air to the combustion part 14 and a controller 20 controlling the electromagnetic pump 18 and the blower 19 to control the air-fuel ratio inside a combustion chamber 37. The controller 20 is provided with a control mode regarding as the cold start time on condition that the temperature of the combustion part 14 is a predetermined set temperature or lower so as to lower the air-fuel ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fuel combustion apparatus, and more particularly, to a liquid fuel combustion apparatus capable of preventing a flame from blowing out in a combustion chamber, which is liable to occur during a cold start.

[0002]

2. Description of the Related Art A liquid fuel combustion apparatus used for a water heater or the like includes a combustion section, fuel supply means and air supply means for supplying liquid fuel and air to the combustion section, A configuration is known that includes a fuel supply unit and a controller that performs predetermined control on the air supply unit so that the fuel supply amount and the air supply amount correspond to the fuel supply amount. Here, the combustion section ignites the liquid fuel scattered into the combustion chamber from the vaporization cylinder provided in the combustion chamber to perform spray combustion, and heats the vaporization cylinder with the combustion heat of the spray combustion to vaporize the vaporization cylinder. The liquid fuel in the cylinder is vaporized, and the vaporized fuel is ejected from a flame hole of a combustion plate through a gas chamber to enable vaporization and combustion. At the time of this vaporization combustion, combustion is performed based on a fuel amount and an air-fuel ratio set in advance corresponding to a required heat output.

[0003]

However, in the above-described liquid fuel combustion apparatus, when the vaporization cylinder is not sufficiently heated immediately after the start of vaporization and combustion, all of the supplied liquid fuel does not vaporize. That is, part of the fuel is directly injected into the combustion chamber from the flame holes of the combustion plate without being vaporized. In this case, since all the supplied fuel is not vaporized, the air-fuel ratio of the air-fuel mixture is necessarily high. That is, the air-fuel mixture supplied into the combustion chamber becomes air-rich, which causes a flame lift state, and in the worst case, inconvenience of blowing out the flame.

[0004] Japanese Patent Application Laid-Open Nos. 2000-74367 and 2000-146166 disclose liquid fuel combustion devices in which the air-fuel ratio is controlled so as to lower the air-fuel ratio during ignition. Therefore, theoretically, if the air-fuel ratio disclosed in each of these publications is applied to the above-described liquid fuel combustion apparatus, the above-described disadvantage that all of the fuel is not vaporized can be improved. .

[0005] However, in the liquid fuel combustion devices disclosed in the above publications, the following inconvenience occurs because the control for lowering the air-fuel ratio is always employed at the time of ignition. That is, when the elapsed time from the stop of combustion is short,
In practice, the temperature of the combustion section is still kept high. Therefore, if the combustion is performed under the condition where the air-fuel ratio is lowered in this state, all of the supplied fuel can be sufficiently vaporized, and the fuel-rich relationship is further strengthened. Occurs, or a part of the supplied fuel remains in the combustion part as unburned fuel.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such inconveniences, and has as its object to reduce the air-fuel ratio at the time of cold start, that is, at the time of ignition when the temperature of the combustion section is low. Control can effectively prevent the lift and blowout of the flame, and at times other than cold start, ignition at a steady air-fuel ratio can avoid soot and unburned fuel It is an object of the present invention to provide a liquid fuel combustion device.

[0007]

In order to achieve the above object, according to the present invention, a spray combustion is performed by igniting liquid fuel scattered from a vaporizing cylinder provided in a combustion chamber into the combustion chamber,
A combustion unit that vaporizes the liquid fuel in the vaporization cylinder by heating the vaporization cylinder with the combustion heat of the spray combustion, and ejects the vaporized fuel from the flame holes of the combustion plate through the gas chamber to perform vaporization combustion. A fuel supply unit that supplies liquid fuel to the combustion unit; an air supply unit that supplies air to the combustion unit; and a controller that controls the fuel supply unit and the air supply unit to control an air-fuel ratio. In the liquid fuel combustion device, the controller is provided with a control mode for lowering the air-fuel ratio during a cold start. With such a configuration, at the time of cold start, the amount of the supplied liquid fuel is relatively increased with respect to the air supply amount, and the air rich which may occur when the engine is started at the steady air-fuel ratio is reduced. Thus, it is possible to prevent the flame from being blown out while preventing the lift state of the flame. On the other hand, in a state where the combustion portion is warmed at the time of starting, that is, in a state where the condition of the cold start is not satisfied, all of the supplied fuel can be vaporized, so that an excessive supply of fuel is performed by controlling at a steady air-fuel ratio. It is also possible to prevent generation of soot and residual unburned fuel without causing soot.

[0008]

According to the present invention, a function of the controller for judging a cold start when the temperature of the combustion section is equal to or lower than a predetermined set temperature, or a process after the fuel supply means stops. A function of judging a cold start when the time is equal to or longer than the set time can be provided selectively or unitedly. With such a configuration, the control can be executed simply by providing a temperature detection function or a timer function. Further, if the temperature detection and the time detection are used in combination, the air-fuel ratio control at the time of the cold start and at the time of the steady start can be executed even if an abnormality occurs in one of the detection devices.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram in which the liquid fuel combustion apparatus according to the present embodiment is applied to a water heater. In this figure, the water heater includes a liquid fuel combustion device 10 and a water supply pipe 12 and a hot water supply pipe 13 connected to the liquid fuel combustion device 10. The liquid fuel combustion device 10 includes a combustion unit 14, a heat exchanger 16 provided on an upper portion of the combustion unit 14 and wound around a heat exchange tube 15 communicating with the water supply pipe 12 and the hot water supply pipe 13. An electromagnetic pump 18 serving as a fuel supply unit for supplying liquid fuel, in this embodiment, kerosene, into the combustion unit 14;
Blower 19 as air supply means for supplying air to the inside
And a predetermined control of the electromagnetic pump 18 and the blower 19, a controller 20 connected to various sensors provided in each part of the device, a remote control of the controller 20 indoors, an ON-OFF switch, and a set temperature. And a remote controller 21 having a timer switch and the like.

A geared motor 22 is connected to the water supply pipe 12.
A water supply amount control valve 23 controlled by the control unit, a water amount sensor 24, an anti-freezing heater 25, and a water temperature thermistor 26 are arranged. On the other hand, the hot water supply pipe 13 is provided with a hot water supply thermistor 28, a mixing tank 29, and a freezing prevention heater 30. Further, an antifreezing heater 3 is provided at an appropriate position on the outer surface of the heat exchanger 16.
In addition to the arrangement of 1, 32 and 33, a burner thermistor 34 is arranged at the bottom of the combustion section 14.

The combustion part 14 includes a bottomed cylindrical outer cylinder 35 disposed at an upper position of the blower 19,
A gas chamber 36 is formed between the outer cylinder 35 and the outer cylinder 35, and a bottomed cylindrical combustion panel 38 having an upper inner space as a combustion chamber 37; It is configured to include a bell-shaped vaporizing cylinder 39 provided and a blower cylinder 40 arranged inside the vaporizing cylinder 39. A large number of flame holes 38A are formed in the combustion plate 38, and a mixture of fuel and air is supplied into the combustion chamber 37 from the flame holes 38A. In the combustion chamber 37, an igniter 42 and a frame rod 43 for detecting a flame in the combustion chamber 37 are arranged.

A fuel diffuser 44 having a fuel receiving groove 44A at a lower end is provided at an upper inside of the vaporizing cylinder 39. A pipe 4 for supplying kerosene is provided in the fuel receiving groove 44A.
6 are arranged facing the discharge port. The vaporizing cylinder 39 is supported by a rotating shaft 48 extending vertically at the center thereof, and the rotating shaft 48 is rotatably provided by a blower motor 50 that drives the blower 19.

The combustion section 14 in the present embodiment is configured as a type that executes two combustion modes. In other words, the initial spray combustion in which fuel is sent into the combustion chamber 37 from the minute gaps formed in the upper and lower portions of the vaporization cylinder 39 to perform combustion, and the vaporization is performed by the heat in the vaporization cylinder 39 heated by the spray combustion. The fuel is mixed with air and sent to the combustion chamber 37 through the flame hole 38A to perform vaporization combustion in which combustion is performed.
Further, the capacity of the liquid fuel combustion device 10 according to the present embodiment is:
Although not particularly limited, 16.8 × 10 ⁶ J or more
10.8 × 10 ⁷ J, a fuel supply amount of 0.5 to 5 liters per hour, and an air supply amount, that is, a fan rotation speed of a blower of 2000 to 5000 rpm are employed.

The controller 20 includes an electromagnetic pump 18
In addition to controlling the operation of each part of the device such as the blower 19, the operation state of the whole system is optimally controlled according to various conditions by using outputs of various sensors as inputs. The controller 20 has a function of calculating a required heat output (heat amount) based on a hot water supply temperature, a hot water supply amount, a water supply temperature, and thermal efficiency, and also has a fuel supply amount, an air supply amount, It is provided with a memory that stores the number of rotations of the blower as a reference set value in a matrix.

Further, the controller 20 has a temperature judging function for determining whether or not to start the engine in a cold state by using the temperature of the combustion section 14 from the burner thermistor 34 as an input. here,
In the present embodiment, although not particularly limited, the case where the temperature of the combustion unit 14 is 30 ° C. or lower is set as the cold start condition, while the condition that the temperature of the combustion unit 14 reaches 60 ° C. is canceled. It is set as a condition.

Reference numeral 51 in FIG. 1 denotes a constant oil leveler for maintaining a constant level of fuel sent from a fuel tank (not shown), and a filter 52 is disposed at an entrance thereof. Reference numeral 53 denotes an igniter transformer.

Next, the operation of the present embodiment will be described.

First, the operation switch is turned on by operating the remote controller 21 and the hot water supply temperature is set. In this state, when it is detected by the water amount sensor 24 that the hot water tap (not shown) is opened and the predetermined water supply flow rate is exceeded, the water supply temperature is taken into the controller 20 via the water temperature thermistor 26 and the set temperature is reduced. Captured by the controller 20. Further, the temperature of the combustion section 14 by the burner thermistor 34 is also controlled by the controller 20.
Is input to

Blower motor 50 and igniter 42
Operate to supply air and ignite, and the vaporization cylinder 39 rotates. At this time, if the temperature of the combustion unit 14 is 30 ° C. or less, the controller 2
0 is regarded as a cold start, and as shown in FIG. 2, the electromagnetic pump 1 is controlled so that the fuel amount increases relatively to the air amount.
8 and the fan speed of the blower 19 are controlled. When the controller 20 detects that the temperature in the combustion section 14 has reached 60 ° C., the rotation speed of the electromagnetic pump 18 and the fan is controlled so as to return to the air-fuel ratio at the time of steady combustion. On the other hand, if the temperature at the start exceeds 30 ° C,
Assuming that the cold start condition is not satisfied, the air-fuel ratio at the time of steady combustion is used.

FIG. 3 is a diagram showing a case where the liquid fuel combustion apparatus is of a fixed output type. Even in the case of a fixed output type, when the temperature reaches 60.degree. Will be returned.

In the above-described embodiment, the case where the cold start is determined based on the temperature of the combustion section 14 has been described. However, the present invention is not limited to this. The controller 20 may measure the elapsed time from when the pump 18 stops, and determine whether or not it is a cold start. In this case, for example, 30 minutes is set as the reference time as the elapsed time, and when 30 minutes or more elapse, a cold start is considered, and the elapse of 3 minutes after the cold start is executed is set as an appropriate release condition. A control for returning to an appropriate air-fuel ratio can be exemplified. In addition, combustion section 1
Alternatively, both the temperature of No. 4 and the elapsed time since the stop of the electromagnetic pump may be detected.

[0023]

As described above, according to the present invention,
Since the controller is provided with a control mode for lowering the air-fuel ratio at the time of a cold start, the amount of the supplied liquid fuel is relatively increased with respect to the air supply amount, and the combustion part is cooled. In this case, it is possible to prevent the flame from being blown out while suppressing the air richness that may occur at the time of preventing the lift state of the flame. Further, in a state where the combustion part is warmed at the time of starting, by controlling with a steady air-fuel ratio, generation of soot and remaining of unburned fuel can be avoided without excessive supply of fuel.

Also, a function of judging a cold start when the temperature of the combustion section is equal to or lower than a predetermined set temperature or a function of judging a cold start when the elapsed time after the stop of the fuel supply means is equal to or longer than the set time. In a configuration in which the function of judging start is selectively or unitedly provided, the above-described control can be executed only by providing a temperature detection function and a timer function.
In particular, in a configuration in which the temperature detection and the time detection are used in combination, the air-fuel ratio control at the time of a cold start can be executed even if an abnormality occurs in one of the detection devices.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment in which a liquid fuel combustion device according to the present invention is applied to a hot water supply system.

FIG. 2 is a diagram showing air-fuel ratio control when the liquid fuel combustion device is of a variable output type.

FIG. 3 is a diagram showing air-fuel ratio control when the liquid fuel combustion device is of a fixed output type.

[Explanation of symbols]

10 ... Liquid fuel combustion device, 14 ... Combustion unit, 18
... Electromagnetic pump (fuel supply means), 19 ... Blower (air supply means), 20 ... Controller, 34 ...
・ Burner thermistor, 37 ・ ・ Combustion chamber, 38 ・ ・ ・ Vaporized cylinder

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[Procedure amendment]

[Submission date] July 27, 2000 (2007.2
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003]

However, in the above-described liquid fuel combustion apparatus, when the vaporization cylinder is not sufficiently heated immediately after the start of vaporization and combustion, all of the supplied liquid fuel does not vaporize. in other words, part of the fuel leads to lift state of things Ku fire flame to vaporize, in the worst case, to lead to a disadvantage that the blow-off of flame.

Claims (3)

[Claims] 1. A liquid fuel scattered into a combustion chamber is ignited from a vaporization cylinder provided in the combustion chamber to perform spray combustion,
A combustion unit that vaporizes the liquid fuel in the vaporization cylinder by heating the vaporization cylinder with the combustion heat of the spray combustion, and ejects the vaporized fuel from the flame holes of the combustion plate through the gas chamber to perform vaporization combustion. A fuel supply unit that supplies liquid fuel to the combustion unit; an air supply unit that supplies air to the combustion unit; and a controller that controls the air supply ratio by controlling the fuel supply unit and the air supply unit in a predetermined manner. In the liquid fuel combustion device, the controller has a control mode for lowering an air-fuel ratio at a cold start. 2. The liquid fuel combustion apparatus according to claim 1, wherein the controller has a function of determining a cold start when the temperature of the combustion section is equal to or lower than a predetermined set temperature. 3. The controller according to claim 1, wherein the controller has a function of determining a cold start when an elapsed time after the stop of the fuel supply means is equal to or longer than a set time. Liquid fuel combustion equipment.