JPH08105610A - Combustion type heater - Google Patents

Abstract

PURPOSE: To improve exhaust emission. CONSTITUTION: A plate-like gasification member 4 is installed in a mixing cylinder 21 of a burner 2 where the outer peripheral part of the gasification member 4 is held with the cylindrical wall of the mixing cylinder. There are installed an injector 3 which supplies fuel to the gasification member 4 and an air pump 82 which supplies combustion air to the burner 2 in conformity with the amount of supply fuel. What is more, a heater member which heats the cylindrical wall of the mixing cylinder 21 is buried at the lowest position of the mixing cylinder 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion type heater, and more particularly to a combustion type heater for preventing incomplete combustion and improving exhaust emission.

[0002]

2. Description of the Related Art A combustion type heater burns a part of engine fuel by a burner to heat the air in the passenger compartment directly or the water supplied to a radiator in the passenger compartment. Is used as an auxiliary heater until the temperature rises sufficiently.

In the burner of such a combustion type heater, the supplied fuel is vaporized and mixed with combustion air (hereinafter, simply referred to as air), and the mixture is ignited and burned by a heater or a glow plug.

FIG. 4 shows an example of a conventional combustion heater. Housing 1 in which a water supply channel 13 to the radiator is formed
A burner 2 is arranged inside. Mixing cylinder 21 of burner 2
A vaporization member 4 formed of a ceramic fiber in a plate shape is provided at the end portion, and the opening of the fuel supply pipe 73 is in contact with the vaporization member 4. Fuel is supplied to the fuel supply pipe 73 from the pump 72 in the tank 71 through the cutoff valve 76.
The fuel that has reached the vaporization member 4 from the fuel supply pipe 73 diffuses widely throughout the vaporization member 4 due to the capillary phenomenon. The vaporizing member 4 is heated by a rod-shaped heater 9 provided close to the vaporizing member 4, and the fuel vaporized and vaporized from the vaporizing member 4 is mixed with the air introduced into the mixing cylinder 21 through the air introduction hole 211 and ignited and burned. .

The high-temperature combustion gas generated by the combustion is ejected from the cylinder opening of the combustion cylinder 22 and flows out to the exhaust port 16 through the combustion gas passage 20 formed around the combustion cylinder 22. Then, during this period, the feed water flowing through the feed water flow path 13 is heated. In order to ensure efficient heat exchange at this time, heat exchange fins 121 are projected from the partition walls of the fluid flow passage 13 into the combustion gas flow passage 20.

Such a combustion type heater is disclosed in, for example, Japanese Patent Laid-Open No. 1-22.
No. 62214, JP-A-4-73503, JP-A-4-214105, USP 4,538,985.
No. etc.

Incidentally, Japanese Patent Application Laid-Open No. 60-29505 discloses an ultrasonic oscillator for vaporizing fuel.

[0008]

By the way, in the above-mentioned conventional combustion heater, the mixing cylinder 21 of the burner is cooled by the low temperature air passing through the air introduction hole 211,
This low-temperature air also enters the cylinder and cools the vaporizing member 4. Most of the outer peripheral portion of the vaporization member 4 is separated from the rod-shaped heater 5 which is a heat source, and the heat of the flame generated in the mixing cylinder 21 is also prevented from being transmitted to the outer peripheral portion by the cold cylinder wall. Therefore, especially at the initial stage of ignition, there is a problem that the outer peripheral portion of the vaporization member 4 does not rise to a temperature sufficient for vaporizing the fuel, and HC due to incomplete combustion is likely to occur.

SUMMARY OF THE INVENTION Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a combustion heater in which exhaust of HC resulting from incomplete combustion is prevented and exhaust emission is improved.

[0010]

In the first structure of the present invention, combustion is provided in which the burner 2 for heating the fluid supplied to the fluid passage 13 is provided in the housing 1 provided with the fluid passage 13. In the type heater, a vaporization member 4 that is held in the cylinder wall of the burner 2 and is provided inside the cylinder to vaporize the supplied fuel, a fuel supply unit 3 that supplies fuel to the vaporization member 4, and a supply fuel amount The air supply means 82 for supplying the combustion air according to the above to the burner 2 and the heating means 6 for heating the cylinder wall of the burner 2 provided with the introduction hole 211 for introducing the supplied combustion air are provided. .

In the second structure of the present invention, the vaporizing member 4 is used.
Is shaped like a plate, and is held by the outer peripheral portion of the cylindrical wall.

In the third structure of the present invention, the heating means is composed of the heater member 6 which generates heat by the power supply from the energizing means 7.

In the fourth structure of the present invention, the heater member 6 is provided at the lowermost position of the cylindrical wall arranged in a horizontal posture.

In the fifth structure of the present invention, the heater member 6 is embedded in the cylindrical wall.

In the sixth aspect of the present invention, the energizing means 7 is used.
Is set to start energizing the heater member 6 prior to the start of combustion of the burner 2.

In the seventh structure of the present invention, the energizing means 7 is provided.
Is set so that the energization of the heater member 6 is stopped after the combustion of the burner 2 is started and the energization of the heater member 6 is restarted for a predetermined time after the combustion of the burner 2 is stopped.

[0017]

In the first construction described above, since the cylindrical wall of the burner is heated by the heating means 6, even if cold combustion air passes through the introduction hole 211 at the beginning of combustion, the temperature does not decrease. Therefore, the vaporization member 4 held on the cylinder wall is not cooled, and it is possible to avoid insufficient vaporization of fuel and incomplete combustion. Further, the heat transfer of the flame generated in the cylinder to the vaporizing member 4 is not hindered by the cold cylinder wall, so that the temperature of the vaporizing member 4 is prevented from lowering and stable combustion is realized. . Furthermore, since the combustion air is also heated to some extent when passing through the introduction hole 211 of the cylinder wall whose temperature has risen, there is no problem that the cold combustion air directly touches the vaporization member 4 to lower its temperature.

In the second structure, the plate-shaped vaporizing member 4 efficiently vaporizes the fuel supplied to the plate surface.

In the third structure, the heater member 6 is easy to control the temperature and is compact.

In the fourth structure, the unburned fuel accumulated at the lowermost position of the cylinder wall is vaporized and eliminated by the heater member 6 provided in this portion, and evaporative emission is prevented.

In the fifth structure, the cylindrical wall is efficiently heated by the heater member 6 embedded inside, and
It is not necessary to secure an installation space for the heater member 6 inside the cylinder.

In the sixth structure, since the cylinder wall is already sufficiently heated at the start of combustion of the burner, it is possible to effectively prevent the occurrence of incomplete combustion from the very beginning of combustion.

In the seventh construction, since the heater member 6 is de-energized after the start of burner combustion in which sufficient radiant heat is obtained from the flame for the vaporizing member 4, power consumption is reduced, and By re-energizing after burner combustion stop,
Evaporative emission is prevented by remaining unburned fuel being vaporized.

[0024]

[First Embodiment] In FIG. 1, a housing 1 of a combustion heater is a pair of left and right half-container bodies 11 and 12 abutted against each other with a partition plate 14 sandwiched between their opening edges. An air supply port 15 and an exhaust port 16 are formed on the upper wall and the lower wall of the portion 11 respectively, and a fluid flow path 13 is formed in the wall of the half-container body 12 to heat the upper wall and the lower wall. It communicates with an inflow port 17 and an outflow port 18 of water as a transmission medium.

A burner 2 is arranged in the center of the housing 1, and a combustion cylinder of the burner 2 is composed of a mixing cylinder 21 and a combustion cylinder 22 which are provided on the front and back of the partition plate 14, respectively. The combustion cylinder 22 is a large-diameter cylindrical body, and the semi-container body 12 communicating with the exhaust port 16 through the through hole 142 of the partition plate 14.
Protrudes into the inner space of. On the other hand, the mixing cylinder 21 is a cylindrical body having a slightly smaller diameter, and projects into the inner space of the half container body 11 communicating with the air supply port 15, and the projecting end thereof is narrowed to the small hole 212. The mixing cylinder 21 and the combustion cylinder 22 communicate with each other through an opening 141 provided at the center of the partition plate 14.

An electromagnetic fuel injection valve (injector) 3 is provided through the end wall of the half-container body 11, and the tip of the injector 3 is fitted into the small hole 212 of the mixing cylinder 21. ing. The injector 3 is a known one used in automobile engines. In the mixing cylinder 21, a plate-shaped vaporizing member 4 is provided at a front position of the injector 3 (on the right side of the drawing). The vaporizing member 4 is a porous disc body made of a sintered metal, and its plate surface is provided so as to cross the inside of the mixing cylinder 21 so as to face the tip of the injector 3, and the outer peripheral portion is joined to the cylinder wall of the mixing cylinder. Has been done. In addition,
A large number of air introduction holes 211 are provided in the cylinder wall of the mixing cylinder 21.

On the back surface of the vaporizing member 4 on the side opposite to the injector 3, a rod-shaped heater member 5 penetrating the top of the cylinder wall of the mixing cylinder 21 arranged horizontally is located in close proximity, and the mixing cylinder 21 An attachment hole extending horizontally in the wall is formed in the bottom portion of the cylinder wall holding the vaporization member 4, and a rod-shaped heater member 6 is provided therein.

Fuel is supplied to the injector 3 from a pump 72 provided in a fuel tank 71. A return pipe 75 provided with a pressure adjusting valve 74 is connected to the fuel supply pipe 73 leading to the injector 3, and excess fuel is returned to the tank 71.

A control device 7 is provided to open / close the injector 3 and energize the heater members 5 and 6, and drive an air pump 82 provided in an air supply pipe 81 leading to the air supply port 15.

In the combustion type heater having the above-mentioned structure, at the time of ignition, as shown in FIG. 2, first, the heater members 5 and 6 are energized ((1) and (2) in FIG. 2) to form the vaporizing member 4 and the mixing cylinder. The wall is sufficiently heated and a small amount of air is supplied from the air pump 82 to the burner 2 ((3) in FIG. 2). The air is supplied from the air supply port 15 through the air introduction hole 211 to the mixing cylinder 21.
Reach inside. In this state, when the injector 3 is energized in a pulsed manner to inject a predetermined amount of fuel and the supply air amount is increased to the stoichiometric air-fuel ratio (time t1 in FIG. 2), the fuel is sprayed on the entire surface of the vaporizing member 4. It vaporizes by heating and mixes with air to start combustion.

At this time, prior to the start of combustion, the mixing cylinder 21
Since the cylinder wall is sufficiently heated in advance by the heater member 6, the temperature of the cylinder wall does not decrease even if cold air passes through the air introduction hole 211. Therefore, the temperature of the outer peripheral portion of the vaporization member 4 provided in contact with the mixing cylinder 21 does not decrease, and the vaporization of the fuel is not sufficient at this portion to cause HC or the like due to incomplete combustion.

The heat of the flame at the start of combustion is also efficiently transmitted to the vaporizing member 4 via the heated cylinder wall of the mixing cylinder 21, and this also prevents the temperature of the outer peripheral portion of the vaporizing member 4 from decreasing. At the same time, the stability of the flame is maintained. Further, when the air passes through the air introducing hole 211, the air is heated to some extent by the temperature of the mixing cylinder 21, so that there is no problem that the cold air directly touches the vaporizing member 4 to lower its temperature.

During steady operation after the start of combustion, the vaporizing member 4 and the mixing cylinder 21 are heated by the heat of the flame, so that the power supply to the heater members 5 and 6 can be stopped (time t2 in FIG. 2).
). Then, while the high-temperature combustion gas flowing out from the opening of the combustion cylinder 22 flows through the combustion gas flow passage 20, the water flowing through the fluid flow passage 13 is heated through the heat exchange fins 121,
The hot water is supplied to a radiator provided in the vehicle compartment to heat the radiator.

When extinguishing the fire, the fuel injection of the injector 3 is stopped to reduce the air supply amount, and the heater members 5 and 6 are energized again (from time t3 to t4 in FIG. 2). As a result, even if the flame is extinguished, the temperatures of the vaporizing member 4 and the mixing cylinder 21 do not decrease, and all the fuel remaining on the vaporizing member 4 is vaporized and mixed with air to complete combustion. In addition, in particular, since the bottom portion of the cylinder wall of the mixing cylinder 21 is heated by the heater member 6, the unburned fuel that may stay there is vaporized and removed by combustion. Further, since the injector 3 provided at the tip of the fuel supply pipe 73 is closed, the fuel remaining in the supply pipe 73 is not vaporized and discharged as it is. Thus, the discharge of HC and unburned fuel during extinguishing is also effectively prevented.

[0035]

[Second Embodiment] Instead of the injector 3 of the first embodiment,
As shown in FIG. 3, the tip of the fuel supply pipe 73 is connected to the half container body 11.
The same effect as that of the above-described embodiment can be obtained even if the end wall of the vaporization member 4 is penetrated from the end wall to the end wall of the mixing cylinder 21 and the opening is brought into contact with the plate surface of the vaporization member 4. Fuel supply pipe 73 in this case
Is opened and closed by a fuel cutoff valve 76 provided therein.

In each of the above embodiments, the heater member for heating the cylinder wall of the mixing cylinder is not limited to the rod shape, but various shapes such as a sheet shape can be used.

[0037]

As described above, according to the combustion type heater of the present invention, since the heating means for heating the cylindrical wall of the burner is provided, the exhaust emission can be greatly improved.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a combustion heater according to a first embodiment of the present invention.

FIG. 2 is a time chart showing a timing of energizing a heater member and the like.

FIG. 3 is an overall sectional view of a combustion heater according to a second embodiment of the present invention.

FIG. 4 is an overall sectional view of a conventional combustion heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 13 Fluid flow path 2 Burner 211 Introduction hole 3 Injector (fuel supply means) 4 Vaporizing member 6 Heater member (heating means) 7 Control device (energizing means) 82 Air pump (air supply means)

Claims (7)

[Claims] 1. A combustion heater in which a burner for heating a fluid supplied to the fluid flow passage is provided in a housing provided with a fluid flow passage, the combustion heater being held by a cylinder wall of the burner and provided in the cylinder. A vaporization member for vaporizing the supplied fuel, fuel supply means for supplying the fuel to the vaporization member, air supply means for supplying the burner with combustion air according to the supplied fuel amount, and the supplied combustion air And a heating means for heating the cylindrical wall of the burner having an introduction hole for introducing the combustion heater. 2. The combustion heater according to claim 1, wherein the vaporizing member is formed in a plate shape, and an outer peripheral portion of the vaporizing member is held by the cylindrical wall. 3. The combustion type heater according to claim 1, wherein the heating means is constituted by a heater member that generates heat by supplying electric power from an energizing means. 4. The combustion heater according to claim 3, wherein the heater member is provided at a lowermost position of the cylindrical wall arranged in a horizontal posture. 5. The combustion heater according to claim 3, wherein the heater member is embedded in the cylindrical wall. 6. The combustion heater according to claim 2, wherein the energizing means is set to start energizing the heater member prior to the start of combustion of the burner. 7. The energizing means is set so as to stop energizing the heater member after the burner starts burning and restart the energizing of the heater member for a predetermined time after the burner stops burning. The combustion heater described.