Combustion heater

Abstract

To reduce exhaust gas of a combustion type heater, and reduce the possibility that accident fire may occur.SOLUTION: A combustion type heater comprises a mixture chamber into which a mixture of fuel and air is introduced, a combustion chamber in which the mixture delivered from the mixture chamber is combusted, a burner part, and a bluff body. The burner part is a connection portion between the combustion chamber and the mixture chamber. The bluff body is arranged inside the burner part so as to have a gap from the inner wall curved surface of the burner part, and is formed in the air.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a combustion heater. [Background technology]

[0002] For example, Patent Document 1 describes a burner arranged to join the exhaust pipe of a vehicle. This burner vaporizes a mixture of fuel and air injected from a fuel injection valve in a vaporization chamber, supplies it to a combustion chamber, and ignites it with an ignition device arranged in the combustion chamber to cause combustion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-41759 A Summary of the Invention [Problem to be solved by the invention]

[0004] When using electricity for heating in hybrid vehicles such as PHVs and EVs such as electric vehicles, the EV driving distance is shortened accordingly. For example, when using heating in winter, the driving distance may be 30-50% of the distance when not using heating. For this reason, the use of combustion heaters for heating in hybrid vehicles and electric vehicles is being considered.

[0005] When using a combustion heater as a heater for a vehicle, it is desirable to use one that has low emissions, taking into consideration use in places with strict exhaust gas regulations, such as geofencing areas. In this regard, a burner that can perform lean combustion, such as the burner in Patent Document 1, is advantageous in terms of reducing NOx, etc. However, lean combustion has a low combustion temperature, which raises concerns about misfires, and the effect of temperature on the lean limit is large. In addition, with burner combustion, the flow rate of the mixed gas slows down when the heat is low, etc., and there is a possibility that the fire in the combustion chamber will backfire into the air-fuel mixture, and there is a limit to the output variable range.

[0006] In view of the above problems, the present invention provides an improved combustion heater that can reduce exhaust gas emissions while reducing the possibility of misfire. [Means for solving the problem]

[0007] The combustion heater of the present invention comprises a mixture chamber into which a mixture of fuel and air is introduced, a combustion chamber for burning the mixture from the mixture chamber, a burner section, and a bluff body. The burner section connects the combustion chamber and the mixture chamber. The bluff body is disposed inside the burner section so as to leave a gap with respect to the curved inner wall surface of the burner section, and is formed hollow. Effect of the Invention

[0008] By hollowing out the bluff body located in the burner section, the heat capacity of the bluff body can be reduced, which makes it easier to maintain the combustion temperature even during lean combustion, reducing the possibility of misfire. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view that shows a schematic diagram of a combustion heater according to a first embodiment of the present invention. [Diagram 2] 1 is an enlarged schematic diagram showing a burner portion of a combustion heater according to a first embodiment of the present invention. FIG. [Diagram 3] FIG. 4 is a schematic diagram showing another configuration example of the burner section of the combustion heater according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be simplified or omitted.

[0011] Embodiment 1 Fig. 1 is a cross-sectional view showing a schematic diagram of a combustion heater according to embodiment 1. The arrows shown in Fig. 1 indicate the flow of a mixture of fuel and air in the combustion heater 1. As shown in Fig. 1, the combustion heater 1 includes a mixture chamber 11, a combustion chamber 12, a burner unit 13, an injector 21, a combustion blower fan 22, an exhaust port 23, and an ignition plug 24.

[0012] The injector 21 injects fuel. The combustion blower fan 22 rotates to take air into the combustion heater 1. The mixture chamber 11 is formed in a cylindrical shape in the main body 1a of the combustion heater 1. The mixture of the fuel from the injector 21 and the air taken in by the combustion blower fan 22 is introduced into the mixture chamber 11 and mixed.

[0013] The combustion chamber 12 is formed in a cylindrical shape in the main body 1a of the combustion heater 1. An ignition plug 24 is attached near the burner section 13 of the combustion chamber 12. The air-fuel mixture sent from the air-fuel mixture chamber 11 is ignited by the ignition plug 24 and combusted. Exhaust gas after combustion is discharged from an exhaust port 23.

[0014] A burner section 13 is formed in a portion of the main body 1a of the combustion heater 1 between the mixture chamber 11 and the combustion chamber 12. That is, the mixture chamber 11 and the combustion chamber 12 are connected via the burner section 13. FIG. 2 is an enlarged view of the burner section 13 of the combustion heater 1. As shown in FIG. 2, the burner section 13 has a cylindrical shape, and both axial end faces of the burner section 13 are open and connected to the mixture chamber 11 and the combustion chamber 12, respectively. A bluff body 30 is arranged inside the burner section 13.

[0015] The bluff body 30 is a hollow cylindrical member. The axial height of the bluff body 30 and the axial height of the burner section 13 are approximately the same. The outer diameter of the bluff body 30 is smaller than the diameter of the burner section 13. The bluff body 30 is disposed such that a certain gap is provided between the curved surface of the outer wall of the bluff body 30 and the curved surface of the inner wall of the burner section 13. The gap between the curved surface of the outer wall of the bluff body 30 and the curved surface of the inner wall of the burner section 13 is the flow path 14 for the air-fuel mixture. The air-fuel mixture in the mixture chamber 11 is introduced into the combustion chamber 12 through this flow path 14.

[0016] In this embodiment, the bluff body 30 of the burner section 13 is made hollow, thereby reducing the heat capacity of the burner section 13. This makes it easier to maintain the combustion temperature even during lean combustion, when the combustion temperature tends to drop, and reduces the possibility of misfire.

[0017] The thickness of the side wall of the bluff body 30 is constant. On the other hand, the thickness d31 of the end face 31 of the bluff body 30 on the mixture chamber 11 side is thicker than the thickness d32 of the end face 32 on the combustion chamber 12 side. As a result, the heat capacity of the bluff body 30 on the combustion chamber 12 side is relatively small, and the heat capacity of the mixture chamber 11 side is relatively large. Therefore, the temperature of the combustion chamber 12 can be increased to enable lean combustion, and the temperature on the mixture chamber 11 side can be relatively decreased to suppress flashback.

[0018] The bluff body 30 is fixed to the main body 1a of the combustion heater 1 by, for example, welding at fixing parts 33 formed at several points on the end part on the air-fuel mixture chamber 11 side. By positioning the fixing parts 33 of the bluff body 30 on the air-fuel mixture chamber 11 side, heat dissipation of the bluff body 30 on the air-fuel mixture chamber 11 side can be promoted and the temperature on the air-fuel mixture chamber 11 side can be lowered. This can further enhance the effect of suppressing flashback. However, the method of fixing the bluff body 30 to the main body 1a is not limited to welding, and the bluff body 30 may be fixed to the fixing parts 33 by, for example, press fitting or the like.

[0019] In the present embodiment, the burner section 13 and the bluff body 30 are cylindrical in shape. However, the present invention is not limited to this, and the burner section 13 and the bluff body may be tapered. An example of this case is shown in FIG. 3.

[0020] In the example of Fig. 3, the burner section 41 and the bluff body 42 are formed into two hollow truncated cone shapes, large and small, whose side surfaces are parallel to each other. The inner wall curved surface of the burner section 41 and the outer wall curved surface of the bluff body 42 are arranged to be parallel to each other. The burner section 41 and the bluff body 42 are also arranged so that the end face side with the larger outer diameter faces the combustion chamber 12 and the end face side with the smaller outer diameter faces the mixture chamber 11. Although not shown, the bluff body 42 is fixed to the main body 1a at a fixing portion, similar to the case of Fig. 2.

[0021] As in the case of FIG. 2, the gap between the inner curved wall surface of the burner portion 41 and the outer curved wall surface of the bluff body 42 becomes the air-fuel mixture flow passage 43. In a cross section perpendicular to the axial direction, the flow passage 43 is formed in an annular shape. When comparing cross sections at different positions in the axial direction, the flow passage 43 has a larger diameter on the side closer to the combustion chamber 12 and a smaller diameter on the side closer to the air-fuel mixture chamber 11. In this way, by making the burner portion 41 and the bluff body 42 tapered, the area of ​​the flow passage 43 changes so as to become larger as it approaches the combustion chamber 12. Therefore, the flow speed of the air-fuel mixture is relatively fast on the air-fuel mixture chamber 11 side and relatively slow on the combustion chamber 12 side. This makes it possible to more effectively suppress flashback.

[0022] In the example of FIG. 3, the width of the flow passage 43 between the burner section 41 and the bluff body 42, i.e., the radial distance between the inner wall curved surface of the burner section 41 and the outer wall curved surface of the bluff body 42, is constant. However, the width of the flow passage 43 is not limited to being constant. For example, the width of the flow passage 43 may be formed so that the mixture chamber 11 side is relatively narrow and the combustion chamber 12 side is relatively wide. This can increase the flow rate of the mixture in the mixture chamber 11, and effectively suppress backfire. Also, the bluff body 42 may be formed so that the thickness of the end face on the mixture chamber 11 side is thick and the thickness of the end face on the combustion chamber 12 side is thin, as in the case of FIG. 2. [Explanation of symbols]

[0023] 1 Combustion heater 1a Main unit 11 Mixture chamber 12 Combustion chamber 13 Burner section 14 Flow Path 21 Injector 22 Combustion blower fan 23 Exhaust port 24 Spark plug 30 Bluff Body 31 End face 32 End face 33 Fixed part 41 Burner section 42 Bluff Body 43 Flow Path

Claims

1. a mixture chamber into which a mixture of fuel and air is introduced; a combustion chamber for combusting the mixture from the mixture chamber; A burner portion connecting the combustion chamber and a mixture chamber; A hollow bluff body is disposed inside the burner section with a gap between the burner section and the inner wall curved surface of the burner section; Equipped with The thickness of the wall surface of the bluff body facing the mixture chamber is thicker than the thickness of the wall surface facing the combustion chamber. A combustion heater characterized by:

2. The internal space of the burner section and the bluff body are formed in a truncated cone shape, The inner curved wall surface of the burner section and the outer curved wall surface of the bluff body are arranged to be parallel to each other, The internal space of the burner section and the bluff body are arranged such that the bottom surface having a larger outer diameter faces the combustion chamber, and the bottom surface having a smaller outer diameter faces the mixture chamber. The combustion heater according to claim 1.

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