CN220793258U - Exhaust structure of indirect fuel heater - Google Patents

Abstract

The utility model provides an exhaust structure of an indirect fuel oil heater, which relates to the technical field of heating equipment. This indirect fuel heater exhaust structure can improve the thermal efficiency, and space heating effect is better.

Description

Exhaust structure of indirect fuel heater

Technical Field

The utility model relates to the technical field of heating equipment, in particular to an exhaust structure of an indirect fuel oil heater.

Background

The indirect fuel heater is a common heating device, and mainly uses heat energy generated by burning fuel oil to indirectly heat air so as to achieve the effect of heating indoor space, but generates a large amount of smoke when the fuel oil is burned, and a structure for exhausting smoke is needed to be arranged on the indirect fuel heater.

The current indirect fuel heater is generally provided with a chimney port to realize smoke exhaust, but the chimney port discharges a large amount of heat while exhausting smoke, so that the heat efficiency of burning and converting clean air heat is lower, and the space heating effect is affected.

Disclosure of Invention

The utility model solves the problems that: how to improve the thermal efficiency of the indirect fuel heater.

In order to solve the problems, the utility model provides an exhaust structure of an indirect fuel heater, which comprises a combustion cylinder and an air guide pipe, wherein the combustion cylinder is provided with a first end wall opposite to a fan of the indirect fuel heater and a second end wall opposite to the fan, the air guide pipe is arranged in the combustion cylinder, one end of the air guide pipe penetrates through the first end wall to form an air guide inlet, and the other end of the air guide pipe penetrates through the second end wall to form an air guide outlet.

Optionally, the air guide pipes are provided in plurality, and the air guide pipes are arranged in the combustion cylinder in a ring manner around the axis of the combustion cylinder.

Optionally, the exhaust structure of the indirect fuel oil heater further comprises an inner cylinder, two ends of the inner cylinder are opened, the inner cylinder is arranged in the combustion cylinder and is coaxially arranged with the combustion cylinder, and one end of the inner cylinder is connected with the first end wall;

a smoke outlet group is arranged on the side wall of the combustion cylinder at a position close to the first end wall;

the air guide pipe is arranged between the outer wall surface of the inner cylinder and the inner wall surface of the combustion cylinder.

Optionally, an end of the inner barrel adjacent to the second end wall is spaced from the second end wall.

Optionally, the exhaust structure of the indirect fuel heater further comprises an inner chimney and an outer chimney, the inner chimney is sleeved on the combustion cylinder, a smoke inlet group communicated with the combustion cylinder is formed in the inner chimney, a chimney mouth is formed in the outer chimney in a sleeved mode, a smoke running gap is formed in the inner wall surface of the outer chimney at intervals with the outer wall surface of the inner chimney, two ends of the smoke running gap are closed, a waveform smoke running channel is arranged in the smoke running gap, and two ends of the waveform smoke running channel are respectively communicated with the smoke inlet group and the chimney mouth.

Optionally, the part of the inner space of the smoke passing gap between the smoke inlet group and the chimney mouth is a smoke passing space, a plurality of smoke blocking strips extending along the axial direction of the inner smoke tube are arranged in the smoke passing space, the smoke blocking strips are sequentially arranged along the circumferential direction of the inner smoke tube, the smoke passing space is divided into a plurality of sub-gaps sequentially distributed along the circumferential direction of the inner smoke tube, two adjacent smoke blocking strips are respectively provided with a notch at two opposite ends, and the notches are communicated with the sub-gaps to form the waveform smoke passing channel.

Optionally, the chimney port is arranged on the upper side of the outer flue;

the two smoke inlet groups are respectively positioned at two sides of the inner smoke tube in the horizontal direction and at the lower position, and one wave-shaped smoke passage is communicated between each smoke inlet group and the chimney.

Optionally, the cigarette inlet is arranged at one end of the inner cigarette tube close to the first end wall;

the chimney port is arranged at one end of the outer chimney, which is close to the second end wall.

Optionally, a smoke outlet group is provided on the side wall of the combustion cylinder near the first end wall, and the smoke outlet group is communicated with the smoke inlet group through a smoke guiding pipe group.

Optionally, the exhaust structure of the indirect fuel heater further comprises an inner chimney, the inner chimney is sleeved on the combustion cylinder, and the inner wall surface of the inner chimney and the outer wall surface of the combustion cylinder are separated by a main air passing gap with two open ends.

Compared with the prior art, the exhaust structure of the indirect fuel heater provided by the utility model has the following technical effects:

in the exhaust structure of the indirect fuel heater, the combustion cylinder is provided with the first end wall and the second end wall, so that when the combustion cylinder is installed in the indirect fuel heater, the first end wall and the fan are arranged oppositely, and the second end wall and the fan are arranged oppositely; meanwhile, the air guide pipe is arranged in the combustion cylinder, so that heat in the combustion cylinder can be greatly dissipated from the inner wall surface of the air guide pipe; in addition, one end of the air guide pipe penetrates through the first end wall to form an air guide inlet, and the other end penetrates through the second end wall to form an air guide outlet, so that air blown by the fan can be sent in from the air guide inlet and out of the air guide outlet to blow heat in the air guide pipe into a room. So, not only the outer wall surface of combustion bowl can dispel the heat, and the guide duct can dispel a large amount of heat in the combustion bowl equally, in comparison in the past, this combustion bowl has increased the guide duct inner wall surface and has regarded as the cooling surface, and the cooling surface is bigger, can take away more heat when the air current flows through, and indirect fuel heater's chimney mouth department exhaust heat just reduces relatively to improve thermal efficiency, space heating effect is better.

Drawings

FIG. 1 is a schematic diagram of an exhaust structure of an indirect fuel heater according to an embodiment of the present utility model;

FIG. 2 is a perspective cross-sectional view of an exhaust structure of an indirect fuel heater according to an embodiment of the present utility model;

FIG. 3 is a schematic diagram of an indirect fuel heater according to an embodiment of the present utility model;

FIG. 4 is a cross-sectional view of an indirect fuel heater according to an embodiment of the present utility model;

FIG. 5 is a horizontal cross-sectional view of an indirect fuel heater exhaust structure according to an embodiment of the present utility model;

FIG. 6 is a top-down cross-sectional view of an indirect fuel heater exhaust structure according to an embodiment of the present utility model;

fig. 7 is a schematic view of an exhaust structure of an indirect fuel heater according to an embodiment of the present utility model with an outer chimney removed.

Reference numerals illustrate:

1-combustion cylinder, 11-first end wall, 12-second end wall, 13-combustion chamber, 14-smoke outlet group, 2-air guide pipe, 21-air guide inlet, 22-air guide outlet, 3-inner cylinder, 4-inner cylinder, 41-smoke inlet group, 411-circular path, 42-smoke guide pipe group, 43-main air passing gap, 5-outer cylinder, 51-chimney mouth, 6-smoke passing gap, 61-wave shape smoke passing channel, 62-smoke passing space, 621-smoke blocking strip, 621 a-gap, 622-sub gap, 7-fan, 8-burner, 9-outer cylinder.

Detailed Description

In order that the above objects, features and advantages of the utility model will be readily understood, a more particular description of the utility model will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.

In the description of the present utility model, it should be understood that, if there are terms "upper", "lower", "front", "rear", "left", "right", the indicated orientation or positional relationship is based on that shown in the drawings, only for convenience of description and simplification of the description, and does not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Further, in the description of the present utility model, the X-axis in the drawings represents the horizontal direction and is designated as the left-right position, and the forward direction of the X-axis represents the left direction, and correspondingly, the reverse direction of the X-axis represents the right direction; the vertical direction, i.e., up and down, is shown in the drawings with the forward direction of the Z axis representing the up and down direction and, correspondingly, the reverse direction of the Z axis representing the down direction, it should be noted that the foregoing X and Z axes are meant only to facilitate the description of the present utility model and simplify the description, and are not indicative or implying that the apparatus or element being referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the present utility model.

As shown in fig. 1 and 2, an embodiment of the present utility model provides an exhaust structure of an indirect fuel heater, the exhaust structure of the indirect fuel heater includes a combustion cylinder 1 and an air guide pipe 2, the combustion cylinder 1 has a first end wall 11 opposite to a fan 7 of the indirect fuel heater and a second end wall 12 opposite to the fan 7, the air guide pipe 2 is disposed in the combustion cylinder 1, one end of the air guide pipe 2 penetrates through the first end wall 11 to form an air guide inlet 21, and the other end penetrates through the second end wall 12 to form an air guide outlet 22.

It should be noted that, the indirect fuel heater generally includes an outer barrel 9, and the exhaust structure of the indirect fuel heater may be disposed in the outer barrel 9 and kept coaxial with the outer barrel 9; a fan 7 is usually arranged in the outer cylinder 9, when the exhaust structure of the indirect fuel heater is arranged in the outer cylinder 9, the first end wall 11 of the combustion cylinder 1 can be arranged opposite to the fan 7, and the second end wall 12 of the combustion cylinder 1 is arranged opposite to the fan 7, so that after the fuel in the combustion cylinder 1 burns to generate heat, the fan 7 can blow air to blow the heat on the outer wall surface of the combustion cylinder 1 to the outside of the outer cylinder 9, and the indoor space is heated; the second end wall 12 of the combustion vessel 1 may be provided with a burner 8, in particular the burner 8 comprises an oil jet and an ignition device, the oxygen being supplied by the fan 7, the burner 8 being turned on to effect combustion of the fuel; a combustion chamber 13 for fuel combustion may be formed in the combustion vessel 1, and the air duct 2 may be provided in the combustion chamber 13 for fuel combustion.

In this embodiment, the combustion can 1 has a first end wall 11 and a second end wall 12, such that, when the combustion can 1 is installed in the indirect fuel heater, referring to fig. 3 and 4, the first end wall 11 is disposed opposite to the fan 7, and the second end wall 12 is disposed opposite to the fan 7; meanwhile, the air guide pipe 2 is arranged in the combustion cylinder 1, so that heat in the combustion cylinder 1 can be greatly dissipated from the inner wall surface of the air guide pipe 2; in addition, by penetrating one end of the air guide duct 2 through the first end wall 11 to form the air guide inlet 21 and the other end through the second end wall 12 to form the air guide outlet 22, the air blown by the blower 7 can be sent in from the air guide inlet 21 and out from the air guide outlet 22 to blow the heat in the air guide duct 2 into the room. So, not only the outer wall surface of combustion bowl 1 can dispel the heat, and guide duct 2 can dispel a large amount of heat equally in the combustion bowl 1, in comparison with the past, this combustion bowl 1 has increased guide duct 2 inner wall surface and has regarded as the cooling surface, and the cooling surface is bigger, can take away more heat when the air current flows through, and indirect fuel heater's chimney mouth 51 department exhaust heat just reduces relatively to improve thermal efficiency, space heating effect is better.

Alternatively, as shown in fig. 1 and 2, a plurality of air guide pipes 2 are provided, and a plurality of air guide pipes 2 are looped around the axis of the combustion cylinder 1 in the combustion cylinder 1.

It should be noted that the number of the air guide pipes 2 may be two or more; the distance between the air guide pipes 2 in the plurality of air guide pipes 2 is not limited, and the plurality of air guide pipes 2 are preferably uniformly distributed at intervals.

In this embodiment, through setting up a plurality of guide duct 2, and a plurality of guide duct 2 are established around the axis ring of combustion bowl 1, so, utilize this a plurality of guide duct 2 can disperse the heat dissipation effect to the different regions of combustion bowl 1 internal edge circumference, realize the even heat dissipation to combustion bowl 1, improve the radiating effect.

Optionally, as shown in fig. 1, 2 and 5, the exhaust structure of the indirect fuel heater further comprises an inner cylinder 3, two ends of the inner cylinder 3 are arranged in an open manner, the inner cylinder 3 is arranged in the combustion cylinder 1 and is coaxially arranged with the combustion cylinder 1, and one end of the inner cylinder 3 is connected with the first end wall 11; a smoke outlet group 14 is arranged on the side wall of the combustion cylinder 1 near the first end wall 11; the air guide pipe 2 is arranged between the outer wall surface of the inner cylinder 3 and the inner wall surface of the combustion cylinder 1.

Specifically, the smoke outlet group 14 includes four smoke outlets, and the four smoke outlets are arranged on the side wall of the combustion cylinder 1 in a field shape; more specifically, two outlet groups 14 are provided.

In this embodiment, by providing the inner tube 3 and the smoke outlet group 14, after the fuel is burned at the first end wall 11 to generate smoke, the smoke will flow toward the smoke outlet group 14, and the flow direction is approximately as follows (refer to the circular path 411 of fig. 5): the flue gas flows toward the second end wall 12 along the axial direction of the inner tube 3 until flowing out of the inner tube 3, then the flue gas flowing out of the inner tube 3 enters between the outer wall surface of the inner tube 3 and the inner wall surface of the combustion tube 1, and then flows to the flue outlet group 14 along the direction toward the first end wall 11. In this way, the whole flow path of the flue gas is in a shape of a circle, and the flow path of the flue gas is longer, so that the heat can be dissipated more fully, and the temperature of the flue gas at the chimney opening 51 is reduced; meanwhile, under a longer flow path, the flue gas and the air guide pipe 2 can have quite long contact time, so that the heat dissipation and conduction of the flue gas to the air guide pipe 2 are effectively increased, and the heat dissipation effect is improved.

Alternatively, as shown in fig. 5, the end of the inner barrel 3 adjacent the second end wall 12 is spaced from the second end wall 12.

In this embodiment, the end of the inner cylinder 3 close to the second end wall 12 is spaced from the second end wall 12, so that the inner cylinder 3 and the second end wall 12 have a certain distance, and the flue gas of the inner cylinder 3 can flow out of the inner cylinder 3 fully.

Optionally, as shown in fig. 2, 5, 6 and 7, the exhaust structure of the indirect fuel heater further comprises an inner chimney 4 and an outer chimney 5, the inner chimney 4 is sleeved on the combustion cylinder 1, the inner chimney 4 is provided with a smoke inlet group 41 communicated with the combustion cylinder 1, the outer chimney 5 is sleeved on the inner chimney 4, the outer chimney 5 is provided with a chimney 51, the inner wall surface of the outer chimney 5 and the outer wall surface of the inner chimney 4 are separated by a smoke outlet gap 6, two ends of the smoke outlet gap 6 are in a closed arrangement, a waveform smoke outlet channel 61 is arranged in the smoke outlet gap 6, and two ends of the waveform smoke outlet channel 61 are respectively communicated with the smoke inlet group 41 and the chimney 51.

Specifically, the smoke inlet group 41 includes four smoke inlets, and the four smoke inlets are arranged on the side wall of the inner chimney 4 in a field shape; more specifically, two smoke inlet groups 41 are provided. Specifically, the smoke passing gap 6 is a cylindrical gap.

In this embodiment, by arranging the wave-shaped smoke-moving channel 61 in the smoke-moving gap 6, and two ends of the wave-shaped smoke-moving channel 61 are respectively connected to the smoke inlet group 41 and the chimney port 51, when smoke flows into the smoke inlet group 41 from the combustion cylinder 1, the smoke flows to the chimney port 51 along the wave-shaped smoke-moving channel 61 in a wave shape, the smoke path is longer, and heat dissipation is more, so as to reduce the smoke temperature at the chimney port 51.

Alternatively, as shown in fig. 5, 6 and 7, the part of the inner space of the smoke passing gap 6 between the smoke inlet group 41 and the chimney 51 is a smoke passing space 62, a plurality of smoke blocking strips 621 extending along the axial direction of the inner chimney 4 are arranged in the smoke passing space 62, the smoke blocking strips 621 are sequentially arranged along the circumferential direction of the inner chimney 4 to divide the smoke passing space 62 into a plurality of sub-gaps 622 sequentially distributed along the circumferential direction of the inner chimney 4, two opposite ends of two adjacent smoke blocking strips 621 are respectively provided with a notch 621a, and the notch 621a and the sub-gaps 622 are communicated to form the waveform smoke passing channel 61.

In this embodiment, as shown in fig. 7, the gaps 621a on each smoke baffle 621 are arranged to enable the sub-gaps 622 on two sides of the smoke baffle 621 to be communicated, the wave-shaped smoke passage 61 can be formed by arranging a plurality of smoke baffles 621 with the gaps 621a in the smoke passage space 62, the wave-shaped smoke passage 61 is simple in composition, only a plurality of smoke baffles 621 are needed, and the installation and the manufacture are convenient.

Alternatively, as shown in fig. 6, a chimney 51 is provided on the upper side of the outer chimney 5; two smoke inlet groups 41 are arranged, the two smoke inlet groups 41 are respectively positioned at two horizontal sides and lower positions on the inner chimney 4, and a wave-shaped smoke passage 61 is communicated between each smoke inlet group 41 and the chimney 51.

In this embodiment, the chimney port 51 is disposed on the upper side of the outer chimney 5, and the smoke inlet group 41 is disposed at a position below the inner chimney 4, that is, two ends of the wave-shaped smoke path 61 are up and the other ends are down, so that the path of the wave-shaped smoke path 61 is as long as possible, heat dissipation is further increased, and heat carried by smoke at the chimney port 51 is reduced; by arranging two smoke inlet groups 41 on two horizontal sides of the inner chimney 4, smoke can flow from two sides of the inner chimney 4 at the same time, and heat dissipation is more effective.

Alternatively, as shown in fig. 7, the smoke inlet group 41 is provided on the inner chimney 4 at an end near the first end wall 11; a chimney 51 is provided on the outer chimney 5 at an end thereof adjacent the second end wall 12.

In this embodiment, by arranging the smoke inlet group 41 at the end of the inner chimney 4 near the first end wall 11, and arranging the chimney 51 at the end of the outer chimney 5 near the second end wall 12, that is, the smoke inlet group 41 and the chimney 51 are respectively positioned at two ends of the exhaust structure, the wave-shaped smoke path 61 is longer, heat dissipation is better, and heat carried by smoke at the chimney 51 is less.

Alternatively, as shown in fig. 6 and 7, a smoke outlet group 14 is provided on the side wall of the combustion cylinder 1 near the first end wall 11, and the smoke outlet group 14 is communicated with the smoke inlet group 41 through a smoke guiding pipe group 42.

Specifically, the smoke outlet group 14 includes four smoke outlets, the smoke guide tube group 42 includes four smoke guide tubes, the smoke inlet group 41 includes four smoke inlets, and the four smoke outlets, the four smoke guide tubes, and the four smoke inlets correspond to each other.

In this embodiment, by providing the smoke guide tube group 42 between the smoke outlet group 14 and the smoke inlet group 41, smoke can flow through four smoke guide tubes at the same time, and the flow is faster, so that the heat dissipation is ensured and the smoke discharging efficiency is higher.

Optionally, the exhaust structure of the indirect fuel heater further comprises an inner chimney 4, the inner chimney 4 is sleeved on the combustion cylinder 1, and the inner wall surface of the inner chimney 4 and the outer wall surface of the combustion cylinder 1 are separated by a main air passing gap 43 with two open ends.

In this embodiment, by separating the inner wall surface of the inner chimney 4 from the outer wall surface of the combustion cylinder 1 by the main air-passing gap 43 with both ends open, the heat of the outer wall surface of the combustion cylinder 1 can flow indoors through the main air-passing gap 43, and the outer wall surface of the combustion cylinder 1 can dissipate heat through the main air-passing gap 43, which is combined with the heat dissipation effect of the air guide pipe 2, so that the heat efficiency is ensured.

In the description of the present utility model, it should be noted that, unless explicitly stated and limited otherwise, the terms "provided," "connected," and "disposed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

In the description of the present utility model, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. As such, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.

Furthermore, in the description of the present utility model, the term "present embodiment" or "present embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or implementation is included in at least one embodiment or implementation of the present utility model. In the present utility model, the schematic representation of the above terms does not necessarily refer to the same examples or implementations. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or implementations.

Although the utility model is disclosed above, the scope of the utility model is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the utility model, and these changes and modifications will fall within the scope of the utility model.

Claims (10)

1. The utility model provides an indirect fuel heater exhaust structure, its characterized in that, indirect fuel heater exhaust structure includes combustion bowl (1) and guide duct (2), combustion bowl (1) have be used for with indirect fuel heater's fan (7) first end wall (11) and be used for with fan (7) second end wall (12) of back to, guide duct (2) are located in combustion bowl (1), one end of guide duct (2) runs through first end wall (11) in order to form wind-guiding entry (21), the other end runs through second end wall (12) in order to form wind-guiding export (22).

2. The exhaust structure of an indirect fuel heater according to claim 1, wherein a plurality of air guide pipes (2) are provided, and a plurality of the air guide pipes (2) are arranged in the combustion cylinder (1) in a circular manner around the axis of the combustion cylinder (1).

3. The exhaust structure of an indirect fuel heater according to claim 1 or 2, further comprising an inner cylinder (3), wherein both ends of the inner cylinder (3) are arranged open, the inner cylinder (3) is arranged in the combustion cylinder (1) and coaxially arranged with the combustion cylinder (1), and one end of the inner cylinder (3) is connected with the first end wall (11);

a smoke outlet group (14) is arranged on the side wall of the combustion cylinder (1) at a position close to the first end wall (11);

the air guide pipe (2) is arranged between the outer wall surface of the inner cylinder (3) and the inner wall surface of the combustion cylinder (1).

4. An exhaust structure of an indirect-fired heater according to claim 3, characterized in that the end of the inner cylinder (3) adjacent to the second end wall (12) is spaced from the second end wall (12).

5. The exhaust structure of an indirect fuel heater according to claim 1, further comprising an inner chimney (4) and an outer chimney (5), wherein the inner chimney (4) is sleeved on the combustion cylinder (1), a smoke inlet group (41) communicated with the combustion cylinder (1) is formed in the inner chimney (4), a chimney (51) is formed in the outer chimney (5) in a sleeved mode, a smoke outlet gap (6) is formed between the inner wall surface of the outer chimney (5) and the outer wall surface of the inner chimney (4), two ends of the smoke outlet gap (6) are arranged in a closed mode, a waveform smoke channel (61) is arranged in the smoke outlet gap (6), and two ends of the waveform smoke channel (61) are respectively communicated with the smoke inlet group (41) and the chimney (51).

6. The exhaust structure of an indirect fuel heater according to claim 5, wherein a portion of the inner space of the smoke passing gap (6) between the smoke inlet group (41) and the chimney port (51) is a smoke passing space (62), a plurality of smoke blocking strips (621) extending along the axial direction of the inner chimney (4) are arranged in the smoke passing space (62), the smoke blocking strips (621) are sequentially arranged along the circumferential direction of the inner chimney (4) so as to divide the smoke passing space (62) into a plurality of sub-gaps (622) sequentially distributed along the circumferential direction of the inner chimney (4), two opposite ends of each adjacent smoke blocking strip (621) are respectively provided with a notch (621 a), and the notches (621 a) and the sub-gaps (622) are communicated to form the waveform smoke passing channel (61).

7. The exhaust structure of an indirect-fired heater according to claim 5, characterized in that the chimney port (51) is provided on the upper side of the outer chimney (5);

two smoke inlet groups (41) are arranged, the two smoke inlet groups (41) are respectively positioned at two horizontal sides and lower positions on the inner chimney (4), and one wave-shaped smoke passage (61) is communicated between each smoke inlet group (41) and the chimney port (51).

8. The exhaust structure of an indirect-fired oil heater according to any of claims 5 to 7, characterized in that said group of smoke inlets (41) is provided on said inner chimney (4) near one end of said first end wall (11);

the chimney opening (51) is arranged at one end, close to the second end wall (12), of the outer smoke tube (5).

9. The exhaust structure of an indirect fuel heater according to claim 8, wherein a smoke outlet group (14) is provided on a side wall of the combustion cylinder (1) near the first end wall (11), and the smoke outlet group (14) is communicated with the smoke inlet group (41) through a smoke guiding pipe group (42).

10. The exhaust structure of an indirect fuel heater according to claim 1, further comprising an inner chimney (4), wherein the inner chimney (4) is sleeved on the combustion cylinder (1), and a main air-passing gap (43) with two open ends is formed between the inner wall surface of the inner chimney (4) and the outer wall surface of the combustion cylinder (1).