JP3275580B2 - Combustion heater - Google Patents

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 in which incomplete combustion or the like is prevented to improve exhaust emission.

[0002]

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

[0003] In such a burner of a combustion type heater, supplied fuel is vaporized and mixed with combustion air (hereinafter simply referred to as air), and the mixture is ignited by a heater or a glow plug and burned.

FIG. 3 shows an example of a conventional combustion type heater. Housing 1 in which supply water channel 13 to radiator is formed
A burner 2 is provided therein. Mixing cylinder 21 of burner 2
At the end, a vaporizing member 4 formed of a ceramic fiber in a plate shape is provided, and the opening of the fuel supply pipe 73 is in contact with the vaporizing member 4. Fuel is supplied to the fuel supply pipe 73 from a pump 72 in the tank 71 via a shutoff valve 76.
The fuel that has reached the vaporizing member 4 from the fuel supply pipe 73 is widely diffused throughout the vaporizing member 4 by capillary action. The vaporizing member 4 is heated by a rod-shaped heater 9 provided in the vicinity, and the fuel vaporized and vaporized from the vaporizing member 4 is mixed with air introduced into the mixing cylinder 21 through the air introduction hole 211 to ignite and burn. .

[0005] The flame generated by the combustion blows out from the cylinder opening of the combustion cylinder 22, and the high-temperature combustion gas flows out to the exhaust port 16 through a combustion gas flow path 20 formed around the combustion cylinder 22. During this time, the supply water flowing through the supply water flow path 13 is heated. In order to ensure efficient heat exchange at this time, heat exchange fins 121 protrude from the partition wall of the fluid passage 13 into the combustion gas passage 20.

Such a combustion type heater is disclosed in, for example,
265444, JP-A-62-163815, JP-A-2-227315 and the like.

[0007]

In the above-mentioned conventional combustion type heater, the temperature of the supply water is adjusted by changing the heating capacity of the heater. This heating capacity is changed by increasing or decreasing the burner combustion capacity. Is going. The increase or decrease in the combustion capacity is performed by changing the supply amounts of the fuel and the air. However, during the change transition, the air-fuel ratio balance between the fuel and the air is lost due to control delay or the like, and the HC concentration in the exhaust gas due to incomplete combustion is reduced. Tends to increase.

In particular, when the combustion capacity is reduced, the radiant heat from the flame to the vaporizing member becomes insufficient, and stable fuel vaporization cannot be guaranteed. As a result,
The flame becomes unstable, which also increases HC emissions.

An object of the present invention is to provide a combustion type heater capable of changing the heating capacity of the heater without deteriorating the exhaust emission.

[0010]

According to a first aspect of the present invention, there is provided a combustion type heater in which a burner for heating a supplied fluid is provided in a housing provided with a fluid flow path. The flow path of the combustion gas flowing out from the second flow path is divided into two, and one flow path 20A is used as a first combustion gas flow path for performing heat exchange with the fluid, and the other flow path 20A is formed.
B is used as a second combustion gas passage that does not exchange heat with the fluid, and the ratio of the combustion gas flowing through both combustion gas passages 20A and 20B is changed so as to achieve a desired fluid temperature. A combustion gas distribution means 91 is provided.

In a second configuration of the present invention, a combustion cylinder 22 of the burner 2 is disposed at the center of the housing 1 and a space between the combustion cylinder 22 and a guide cylinder 23 concentrically disposed outside thereof. Is formed as the second combustion gas flow path 20B, and the first combustion gas flow path is formed between the guide cylinder 23 and the partition wall 122 of the cylindrical fluid flow path 13 located concentrically outside the guide cylinder 23. 20A.

In the third configuration of the present invention, the first combustion gas flow path 20A and the second combustion gas flow path 20B are joined downstream, and the two combustion gas flow paths 20A, 20
A butterfly valve 91 for reciprocally opening and closing B is provided to serve as the combustion gas distribution means.

[0013]

In the first configuration, when the heating capacity of the heater is to be increased, the first combustion gas is distributed by the combustion gas distribution means 91.
A large amount of combustion gas flows through the combustion gas flow path 20A. As a result, the amount of heat exchange with the fluid flowing through the fluid channel 13 increases, and the heating of the fluid increases. On the other hand, when the heating capacity of the heater is reduced, the second
A large amount of combustion gas flows through the combustion gas flow path 20B. As a result, the amount of heat exchange with the fluid flowing through the fluid flow path 13 decreases, and the heating of the fluid decreases.

Thus, the fluid can be set at a desired temperature by increasing or decreasing its heating capacity without changing the combustion capacity of the heater. Since the combustion capacity is not changed, the problem that the air-fuel ratio balance between air and fuel is lost, or combustion instability occurs when the combustion capacity is reduced and the exhaust emission deteriorates can be avoided.

In the second configuration, the guide cylinder 2 is disposed between the combustion cylinder 22 and the cylindrical partition 122 which are concentrically positioned.
3 is provided, and each combustion gas flow path 20 is provided inside and outside the guide cylinder 23.
Since the A and 20B are formed, the heater size can be reduced while securing a sufficient flow area.

In the third configuration, the ratio of the combustion gas flowing through both combustion gas passages 20A and 20B can be freely changed by one butterfly valve 91.

[0017]

Embodiment 1 In FIG. 1, a housing 1 of a combustion type heater has a pair of left and right half-containers 11 and 12 which abut against each other with a thick partition plate 14 sandwiched between opening edges thereof. The air supply port 15 is provided on the upper wall of the half container
Exhaust ports 16 and 19 are formed in 4. Half container 12
Is formed as a double cylinder, and a supply water flow path 13 as a fluid flow path is formed in the wall, and communicates with an inflow port 17 and an outflow port 18 provided in an upper wall and a lower wall.

A burner 2 is disposed 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 respectively provided on the front and back of a partition plate 14. The combustion cylinder 22 is a cylindrical body and protrudes into the inner space of the half-container body 12, and a guide cylinder 23 is disposed concentrically at a certain interval around the entire circumference thereof. This guide tube 23
The base end is fixed to the partition plate 14, and the opening at the distal end thereof is flush with the opening of the combustion tube 22. On the other hand, the mixing cylinder 21 is a slightly small-diameter cylindrical body, which protrudes into the inner space of the half-container body 11 communicating with the air supply port 15, and its protruding end is narrowed to the small hole 212. These mixing cylinder 21 and combustion cylinder 22
Communicate with each other through an opening 141 provided at the center of the partition plate 14.

An annular space between the combustion tube 22 and the guide tube 23 forms a combustion gas passage 20B, which communicates with an exhaust port 19 formed in the partition plate 14 at the lower end of the outer periphery. Further, the annular space between the guide cylinder 23 and the partition wall 122 of the supply water channel 13 which is located concentrically around the entire circumference thereof is a combustion gas channel 20A, which is formed in the partition plate 14 at the lower end of the outer periphery. The exhaust port 16 is formed to communicate with the exhaust port 16.
Note that heat exchange fins 121 extending in the cylinder axis direction and projecting into the combustion gas flow path 20A are formed at a plurality of positions in the circumferential direction on the inner peripheral surface of the partition wall 122.

Each of the exhaust ports 16 and 19 has an exhaust pipe 92,
The exhaust pipes 92 and 93 reach a valve housing 94 provided downstream, are connected to adjacent side walls, and open into the valve housing 94. One exhaust pipe 95 protrudes from the valve housing 94. A butterfly valve 91 that rotates from one side wall to the other side wall is provided in the valve housing 94. When the butterfly valve 91 is at the position indicated by the solid line in the drawing, the exhaust pipe 93 is closed and The exhaust pipe 92 is open. When the butterfly valve 91 rotates 90 degrees to the position shown by the broken line in the figure, the exhaust pipe 93 is opened and the exhaust pipe 92 is closed. When the butterfly valve 91 is at the intermediate rotation position, the opening degrees of the exhaust pipes 92 and 93 are reciprocally changed according to the position.

An electromagnetic fuel injection valve (injector) 3 is provided in an end wall of the half container body 11 so as to penetrate therethrough.
The tip of the injector 3 is a small hole 212 of the mixing cylinder 21.
Is fitted inside. The injector 3 is a known one used for an automobile engine. A plate-shaped vaporizing member 4 is provided in the mixing cylinder 21 at a position in front of the injector 3 (to the right in the drawing). The vaporizing member 4 is a porous disk made of a sintered metal, the plate surface of which is provided so as to cross the inside of the mixing cylinder 21 facing the tip of the injector 3, and the outer peripheral portion is formed on the cylinder wall of the mixing cylinder 21. Are joined.
On the back surface of the vaporizing member 4 opposite to the injector 3, a rod-shaped heater member 5 penetrating the top of the wall of the mixing cylinder 21 disposed horizontally is located in close proximity. The mixing cylinder 21
A large number of air introduction holes 211 are provided in the cylindrical wall of.

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 regulating valve 74 is connected to a fuel supply pipe 73 leading to the injector 3, and excess fuel is returned to the tank 71.

A control device 6 is provided for opening and closing the injector 3 and energizing the heater member 5.
Air pump 8 provided in air supply pipe 81 leading to air supply port 15
2 and controls the rotation of the butterfly valve 91 so as to heat the supply water to a desired temperature according to the vehicle interior set temperature.

In the combustion type heater having the above-described structure, at the time of ignition, the heater member 5 is energized to sufficiently heat the vaporizing member 4 and a small amount of air is supplied from the air pump 82 to the burner 2.
To supply. Air is supplied from air supply port 15 to air introduction hole 21
1 and the inside of the mixing cylinder 21. In this state, when the injector 3 is energized in a pulsed manner to inject a predetermined amount of fuel and increase the supplied air amount to the stoichiometric air-fuel ratio, the fuel is sprayed over the entire surface of the vaporizing member 4 to be heated and vaporized, and mixed with the air. To start burning.

The flame after combustion is blown out from the opening of the combustion tube 21, and the high-temperature combustion gas flows out of the exhaust ports 16 and 19 through both the combustion gas flow paths 20A and 20B. Here, the flow path 20
The combustion gas flowing through A efficiently exchanges heat with the supply water flowing through the supply water flow path 13 by the heat exchange fins 121 to heat it. The heated supply water is supplied to a radiator provided in the passenger compartment to perform heating. On the other hand, the flow path 20B
Is discharged without heat exchange with the supply water.

The ratio of the combustion gas flowing through the two combustion gas passages 20A and 20B can be freely changed by rotating the butterfly valve 91 in the valve housing 94 to an appropriate position. That is, when the supply water needs to be further heated in order to increase the vehicle interior temperature, the rotation position of the butterfly valve 91 is adjusted to increase the amount of combustion gas flowing through the combustion gas passage 20A. As a result, the amount of heat given to the supply water increases, and the temperature increases. Conversely, when lowering the temperature of the supply water, the butterfly valve 91 is rotated to increase the amount of combustion gas flowing through the combustion gas passage 20B. As a result, the amount of heat given to the supply water decreases, and its temperature decreases.

Thus, the heater heating capacity for heating the supply water is changed by changing the ratio of the combustion gas flowing through the two combustion gas passages 20A and 20B while keeping the combustion capacity constant. In addition, incomplete combustion does not occur at the time of a change transition, and the exhaust emission is greatly improved. Further, since the combustion performance is kept constant, the flame does not become unstable.

[0028]

Embodiment 2 Instead of the injector 3 of Embodiment 1,
As shown in FIG. 3, the tip of the fuel supply pipe 73 is connected to the half container 11.
The same effect as in the above embodiment can be obtained by a structure in which the end wall of the mixing cylinder 21 is penetrated from the end wall of the mixing tube 21 and the opening thereof is in contact with the plate surface of the vaporizing member 4. Fuel supply pipe 73 in this case
Is opened and closed by a fuel shut-off valve 76 provided on this.

[0029]

As described above, according to the combustion type heater of the present invention, the heating capacity of the fluid can be changed while the combustion capacity is kept constant. Exhaust emissions can be prevented from deteriorating due to combustion or unstable combustion.

[Brief description of the drawings]

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

FIG. 2 is an overall sectional view of a combustion heater according to a second embodiment of the present invention.

FIG. 3 is an overall sectional view of a conventional combustion heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 13 Supply water flow path (fluid flow path) 122 Partition wall 2 Burner 20A, 20B Combustion gas flow path 22 Combustion cylinder 23 Guide cylinder 91 Butterfly valve (combustion gas distribution means)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-128914 (JP, A) JP-A 63-110852 (JP, U) JP-A 60-121152 (JP, U) JP-A 3- 70509 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60H 1/03

Claims (3)

(57) [Claims] 1. A combustion type heater in which a burner for heating a supplied fluid is provided in a housing provided with a fluid flow path, wherein a flow path of combustion gas flowing out of the burner is divided into two parts. Flow path for the first heat exchange with the fluid
To form a second combustion gas flow path that does not exchange heat with the fluid, and to achieve a desired fluid temperature. A combustion gas distributing means for changing a ratio of combustion gas flowing through the combustion heater. 2. A combustion cylinder of the burner is disposed at the center of the housing, and a second combustion gas flow path is formed between the combustion cylinder and a guide cylinder concentrically disposed outside the combustion cylinder. 2. The combustion type heater according to claim 1, wherein the first combustion gas passage is formed between the guide cylinder and a partition wall of the cylindrical fluid passage located outside the guide cylinder. 3. A method according to claim 1, wherein the first combustion gas flow path and the second combustion gas flow path are joined downstream, and a butterfly valve for reciprocally opening and closing the two combustion gas flow paths is provided at the junction. 3. The combustion heater according to claim 1, wherein the heater serves as a gas distribution unit.