Combustion chamber structure and engine with same

Abstract

The utility model provides a combustion chamber structure and an engine with the same, the combustion chamber structure comprises a combustion chamber, an oil injector is arranged in the combustion chamber, the oil injector is used for injecting oil, the injected oil forms a first oil film and a second oil film, and the first oil film is close to the bottom of the combustion chamber relative to the second oil film; the first contour surface is arranged in the combustion chamber, and the first contour surface extends from the middle part of the combustion chamber to the edge direction of the combustion chamber; wherein at least part of the first contour surface is parallel to the plane where the first oil film is located. The problem that in the prior art, the reliability of a combustion system is reduced due to the fact that the compression ratio of a combustion chamber is increased is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of engine combustion chamber structure design, in particular to a combustion chamber structure and an engine having the same. Background Art

[0002] As the demand for diesel engine emission regulations gradually increases and the call for carbon emissions and carbon balance becomes stronger, diesel engines are widely used in both road and non-road fields as a mobile power source. The combustion of diesel engines is a mixed combustion process with diffusion combustion as the main method and premixed combustion as the auxiliary method. The premixed gas formed during the ignition delay period is compressed and ignited near the top dead center to form premixed combustion. The main combustion process is the diffusion combustion process of continuous injection mixing after compression ignition. The combustion speed and combustion quality of this process mainly depend on the formation speed and uniformity of the mixture. The oil-gas mixing process mainly relies on the mutual coordination of the air flow movement in the cylinder, fuel injection and the combustion chamber structure.

[0003] At present, the main measure to improve the thermal efficiency of diesel engines is to increase the compression ratio. However, the increase in compression ratio, on the one hand, reduces the volume of the combustion chamber, reduces the proportion of effective volume, weakens the ability of the combustion chamber to organize oil and gas mixing, and gradually exposes the problem of smoke emissions; on the other hand, with the increase of compression ratio, the temperature and pressure at the end of compression increase, the maximum combustion temperature in the cylinder increases, and the heat transfer loss near the wall in the cylinder increases, which hinders the further improvement of thermal efficiency and reduces the reliability of the combustion system. Utility Model Content

[0004] The main purpose of the utility model is to provide a combustion chamber structure and an engine having the same, so as to solve the problem in the prior art that the reliability of the combustion system is reduced due to the increase in the compression ratio of the combustion chamber.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a combustion chamber structure is provided, including: a combustion chamber, in which an injector is arranged, the injector is used to inject oil, and the injected oil forms a first oil film and a second oil film, and the first oil film is close to the bottom of the combustion chamber relative to the second oil film; a first contour surface, arranged in the combustion chamber, and the first contour surface extends from the middle of the combustion chamber toward the edge of the combustion chamber; wherein, at least a portion of the first contour surface is arranged parallel to the plane where the first oil film is located.

[0006] Furthermore, the angle between the first oil film and the second oil film is B, an intermediate film body is provided between the first oil film and the second oil film, the angle between the intermediate film body and the first oil film or the second oil film is half of the angle B, the angle between the intermediate film body and the center line of the combustion chamber is C, and the angle between the first contour surface and the center line of the combustion chamber is A;

[0007] ∠A=∠C-∠B / 2(∠C>∠A>∠B).

[0008] Furthermore, the combustion chamber structure also includes: a second contour surface, at least a portion of the second contour surface is opposite to the injector, and the second contour surface is connected to the first contour surface; a chamber top surface, the injector is arranged on the chamber top surface, and the extension height of the injector from the chamber top surface toward the second contour surface is H; the vertical distance between the chamber top surface and the second contour surface is H1, H1=H+(1mm~2mm).

[0009] Furthermore, the width of the second contour surface is L1, and the range of L1 is 1.5 mm to 3 mm.

[0010] Furthermore, the combustion chamber structure also includes: a third contour surface connected to a side of the first contour surface close to the edge of the combustion chamber, at least a portion of the third contour surface is an arc-shaped surface, and the third contour surface is used to block oil.

[0011] Furthermore, the third contour surface includes: a first connecting segment surface, a second connecting segment surface, a third connecting segment surface and a fourth connecting segment surface connected in sequence, the first connecting segment surface is connected to the second contour surface at one end away from the second connecting segment surface, the first connecting segment surface is a first curved surface, the second connecting segment surface is a second curved surface, the third connecting segment surface is a third curved surface, and the fourth connecting segment surface is a fourth curved surface; the radius of the arc where the first curved surface is located is R1, and R1 is 1mm to 1.5mm; the radius of the arc where the second curved surface is located is R2, and R2 is 8mm to 15mm; the radius of the arc where the third curved surface is located is R3, and R3 is 12mm to 18mm; the radius of the arc where the fourth curved surface is located is R4, and R4 is 3mm to 6mm.

[0012] Furthermore, the combustion chamber structure also includes: a fourth contour surface, one end of the fourth contour surface is connected to the third contour surface, and the other end of the fourth contour surface is connected to the side wall of the combustion chamber; the fourth contour surface extends in the horizontal direction, and the maximum vertical distance between the fourth contour surface and the third contour surface is H2; H2 is 3mm to 5mm.

[0013] Furthermore, the combustion chamber structure also includes: a fifth contour surface, the two ends of which are respectively connected to the first contour surface and the third contour surface; the fifth contour surface includes a convex surface, the convex surface protrudes toward the direction close to the injector, and the convex surface is opposite to the nozzle of the injector.

[0014] Furthermore, the fifth contour surface also includes: a fifth connecting surface segment and a sixth connecting surface segment, the two ends of the fifth connecting surface segment are respectively connected to the first contour surface and the convex surface, and the two ends of the sixth connecting surface segment are respectively connected to the convex surface and the third contour surface; the fifth connecting surface segment and the sixth connecting surface segment are respectively arc-shaped surfaces.

[0015] According to another aspect of the present invention, an engine is provided, comprising an engine body and a combustion chamber structure, wherein the combustion chamber structure is arranged in the engine body, and the combustion chamber structure is the above-mentioned combustion chamber structure.

[0016] According to the technical solution of the present invention, a combustion chamber structure includes a combustion chamber, wherein an injector is provided in the combustion chamber, and the injector is used to inject oil into the combustion chamber, thereby realizing engine ignition. The oil injected by the injector forms a first oil film and a second oil film. The first oil film is closer to the bottom of the combustion chamber than the second oil film. Since the injector radially injects oil, the first oil film and the second oil film formed are conical surfaces. A first contour surface is provided in the combustion chamber, and the first contour surface extends from the middle of the combustion chamber toward the edge of the combustion chamber; wherein, at least a part of the first contour surface is arranged parallel to the plane where the first oil film is located, thereby ensuring that the first contour surface and the first oil film achieve optimal parallel fit, preventing the first contour surface from interfering with fuel injection, effectively preventing oil from accumulating on the bottom inner cavity surface of the combustion chamber, reducing the thermal load of the piston pin, and improving the reliability of the high compression ratio combustion system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of this application are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 A structural schematic diagram of an embodiment of a combustion chamber structure according to the present utility model is shown;

[0019] Figure 2 A schematic diagram showing the connection between the fourth contour surface and the third contour surface of the combustion chamber structure according to the present invention is shown;

[0020] Figure 3 A structural schematic diagram of the third contour surface of the combustion chamber structure according to the present utility model is shown.

[0021] The above drawings include the following reference numerals:

[0022] 10. Combustion chamber; 101. Injector; 11. First contour surface; 12. Second contour surface; 13. Chamber top surface; 14. Third contour surface; 141. First connecting segment surface; 142. Second connecting segment surface; 143. Third connecting segment surface; 144. Fourth connecting segment surface; 15. Fourth contour surface; 16. Fifth contour surface; 160. Protruding surface; 161. Fifth connecting surface segment; 162. Sixth connecting surface segment; 210. First oil film; 220. Second oil film. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] Please refer to Figures 1 to 3 The utility model provides a combustion chamber structure, including: a combustion chamber 10, in which an injector 101 is arranged, and the injector 101 is used to inject oil, and the injected oil forms a first oil film and a second oil film, and the first oil film is closer to the bottom of the combustion chamber 10 relative to the second oil film; a first contour surface 11, which is arranged in the combustion chamber 10, and the first contour surface 11 extends from the middle of the combustion chamber 10 toward the edge of the combustion chamber 10; wherein, at least a portion of the first contour surface 11 is arranged parallel to the plane where the first oil film is located.

[0025] According to the combustion chamber structure provided by the present application, it includes a combustion chamber 10, in which an injector 101 is provided. The injector 101 is used to inject oil into the combustion chamber 10, thereby realizing engine ignition. The oil injected by the injector 101 forms a first oil film 210 and a second oil film 220. The first oil film is closer to the bottom of the combustion chamber 10 than the second oil film. Since the injector 101 injects oil radially, the first oil film 210 and the second oil film 220 formed are conical surfaces. A first contour surface 11 is provided in the combustion chamber 10, and the first contour surface 11 extends from the middle portion of the combustion chamber 10 toward the edge of the combustion chamber 10; wherein, at least a portion of the first contour surface 11 is arranged parallel to the plane where the first oil film is located, thereby ensuring that the first contour surface 11 and the first oil film 210 achieve optimal parallel fit, preventing the first contour surface 11 from interfering with fuel injection, effectively preventing oil from accumulating on the bottom inner surface of the combustion chamber 10, reducing the thermal load on the piston pin, and improving the reliability of the high compression ratio combustion system.

[0026] Specifically, the angle between the first oil film and the second oil film is B, an intermediate film body is provided between the first oil film and the second oil film, the angle between the intermediate film body and the first oil film or the second oil film is half of the angle B, the angle between the intermediate film body and the center line of the combustion chamber 10 is C, and the angle between the first contour surface 11 and the center line of the combustion chamber 10 is A;

[0027] ∠A = ∠C - ∠B / 2 (∠C > ∠A > ∠B). The diffusion angle of the fuel beam varies with different injector flow rates. A higher injector flow rate results in a larger diffusion angle, ∠B, and vice versa. By limiting the sizes of ∠A, ∠B, and ∠C, we ensure that the slope surface of Zone 1 achieves optimal parallel alignment with the fuel beam.

[0028] In a specific implementation, the combustion chamber structure further includes: a second contoured surface 12, at least a portion of which faces the injector 101 and is connected to the first contoured surface 11; a chamber top surface 13, on which the injector 101 is disposed, extending from the chamber top surface 13 toward the second contoured surface 12 by a height H; and a vertical distance H1 between the chamber top surface 13 and the second contoured surface 12, where H1 = H + (1 mm to 2 mm). This arrangement ensures that the fuel head does not strike the piston at top dead center.

[0029] The width of the second contour surface 12 is L1, which ranges from 1.5mm to 3mm. This, combined with the relationship between H1 and H, prevents the oil stream from striking the slope structure in Area 1 while also fine-tuning the piston compression ratio. This reduces the volumetric contribution of this area and prevents wall interference with fuel injection (from the center of the fuel injection to the slope). Furthermore, the elevation of the intermediate platform and slope increases the distance between the piston bottom cavity surface and the combustion chamber inner wall, lowering the temperature of the bottom cavity surface and the piston pin area. This effectively prevents oil gelling on the bottom cavity surface, reduces the thermal load on the piston pin, and improves piston reliability to a certain extent.

[0030] The combustion chamber structure further includes: a third contour surface 14, which is connected to the side of the first contour surface 11 close to the edge of the combustion chamber 10. At least part of the third contour surface 14 is an arc-shaped surface, and the third contour surface 14 is used to block the oil. As the piston moves downward, it moves to the space between the third contour surface 14 and the inner wall of the combustion chamber 10 ( Figure 1 The mixed gas in zone 2) forms Figure 1 and Figure 2 The airflow rotation phenomenon shown in the figure is designed according to the flow field shape of the rotating airflow, so that the arc features of the two areas are designed to follow the tangent direction of the rotating airflow to enhance the airflow rotation intensity in the area.

[0031] Furthermore, the third contour surface 14 includes: a first connecting segment surface 141, a second connecting segment surface 142, a third connecting segment surface 143 and a fourth connecting segment surface 144 connected in sequence. The end of the first connecting segment surface 141 away from the second connecting segment surface 142 is connected to the second contour surface 12. The first connecting segment surface 141 is a first arcuate surface, the second connecting segment surface 142 is a second arcuate surface, the third connecting segment surface 143 is a third arcuate surface, and the fourth connecting segment surface 144 is a fourth arcuate surface.

[0032] The radius of the arc where the first arc-shaped surface is located is R1, and R1 is 1 mm to 1.5 mm;

[0033] The radius of the arc where the second arc-shaped surface is located is R2, and R2 is 8mm to 15mm;

[0034] The radius of the arc where the third arc-shaped surface is located is R3, and R3 is 12 mm to 18 mm;

[0035] The radius of the arc where the fourth arc-shaped surface is located is R4, and R4 is 3 mm to 6 mm.

[0036] On the one hand, this setting enhances the airflow rotation, which increases the combustion speed in the later stage, is beneficial to promote the later soot oxidation process to reduce soot emissions, and can also improve fuel economy; on the other hand, the airflow rotation phenomenon can effectively inhibit the diffusion of fuel to the inner wall of the cylinder liner, forming an air barrier between the oil beam and the inner wall of the cylinder liner, which can not only reduce the heat transfer of the inner wall of the cylinder liner, but also greatly improve the problems of oil consumption and aging of the inner wall of the cylinder liner.

[0037] In the present application, the combustion chamber structure further includes: a fourth contour surface 15, one end of which is connected to the third contour surface 14, and the other end of which is connected to the side wall of the combustion chamber 10; the fourth contour surface 15 extends horizontally, and the maximum vertical distance between the fourth contour surface 15 and the third contour surface 14 is H2; H2 is 3mm to 5mm. When designing the zone 2 recessed structure, the arc structure is adjusted to adapt to the flow field motion characteristics, and H2 (pit depth) needs to be designed according to different injector cone angles. When the injector cone angle increases, the fuel allocated to the upper space of the combustion chamber increases, and H2 needs to be deepened to increase the proportion of the upper combustion chamber space, so that the upper and lower combustion chamber space distribution matches the injector cone angle.

[0038] The combustion chamber structure further includes a fifth contoured surface 16, the ends of which are connected to the first contoured surface 11 and the third contoured surface 14, respectively. The fifth contoured surface 16 includes a convex surface 160, which protrudes toward the injector 101 and faces the nozzle of the injector 101. The fifth contoured surface 16 also includes a fifth connecting surface segment 161 and a sixth connecting surface segment 162. The ends of the fifth connecting surface segment 161 are connected to the first contoured surface 11 and the convex surface 160, respectively. The ends of the sixth connecting surface segment 162 are connected to the convex surface 160 and the third contoured surface 14, respectively. The fifth connecting surface segment 161 and the sixth connecting surface segment 162 are both arcuate surfaces. After the fuel beam hits the throat (protruding surface 160), it forms a vortex in the upper and lower areas of the throat, promoting oil-gas mixing. The upward-moving fuel is blocked by the oil baffle (first connecting section 141), and most of the combustion rushes to the bottom surface of the cylinder head. After hitting the bottom surface of the cylinder head, it quickly diffuses to both sides of the impact point. On the one hand, the protruding design of the oil baffle forms a collision and diffusion process of the fuel, accelerating the combustion speed in the middle and late stages; on the other hand, the existence of the oil baffle here prevents the fuel from directly diffusing near the cylinder liner, greatly reducing the near-wall combustion of the mixture of the cylinder liner, which not only reduces the heat transfer of the cylinder liner, but also reduces reliability problems such as oil aging and oil carbon content.

[0039] The utility model also provides an engine, comprising an engine body and a combustion chamber structure. The combustion chamber structure is arranged in the engine body, and the combustion chamber structure is the combustion chamber structure of the above embodiment.

[0040] With the combustion chamber structure of the present application, it is difficult for the oil beam to reach area 1 during diffusion and entrainment. Therefore, when designing a high compression ratio combustion chamber, this area is minimized to improve the utilization of the combustion chamber space. The wall surface at the middle slope is designed to be close to the outer peripheral surface of the fuel diffusion, such as Figure 1 As shown, Zone 1 optimizes the intermediate platform height H1, platform width L1, and slope angle ∠A based on the injector cone angle ∠C and the fuel beam diffusion angle ∠B. The fuel beam diffusion angle varies with injector flow rates: higher injector flow rates increase the diffusion angle ∠B, and vice versa. At the beginning of combustion chamber design, the injector oil beam diffusion angle ∠B of the pre-adopted flow rate of the combustion system is first determined through simulation calculation or constant volume bomb spray test, and then the exact spatial position of the oil beam is located in the drawing software according to the oil beam diffusion angle ∠B and the injector cone angle ∠C. Then, the above H1, L1 and ∠A are adjusted according to the spatial position of the oil beam. The numerical relationship between ∠A, ∠B, and ∠C is as follows: ∠A=∠C-∠B / 2 (∠C>∠A>∠B), so as to ensure that the slope surface of zone 1 can achieve the best parallel fit with the oil beam, and then adjust the longitudinal and lateral position of the slope structure of zone 1 through H1 and L1. First, H1 should be 1mm-2mm larger than the protruding height of the injector oil head (the protruding size of the top of the injector relative to the bottom surface of the cylinder head) to ensure that the oil head does not hit the piston at the top dead center, and then adjust L1 so that the oil beam does not hit the slope structure of zone 1 while fine-tuning the piston compression ratio. The purpose of reducing the volume share of this area and preventing the wall from interfering with fuel injection (from the middle of the fuel injection to the slope surface) is achieved. In addition, due to the raising of the middle platform and the slope, the distance between the inner cavity surface of the bottom of the piston and the inner wall surface of the combustion chamber is increased, and the temperature of the bottom inner cavity surface and the piston pin area is reduced, which effectively prevents the oil from gelling on the bottom inner cavity surface, reduces the thermal load of the piston pin, and improves the reliability of the piston to a certain extent.

[0041] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0042] According to the combustion chamber structure provided by the present application, it includes a combustion chamber 10, in which an injector 101 is provided. The injector 101 is used to inject oil into the combustion chamber 10, thereby realizing engine ignition. The oil injected by the injector 101 forms a first oil film 210 and a second oil film 220. The first oil film is closer to the bottom of the combustion chamber 10 than the second oil film. Since the injector 101 injects oil radially, the first oil film 210 and the second oil film 220 formed are conical surfaces. A first contour surface 11 is provided in the combustion chamber 10, and the first contour surface 11 extends from the middle portion of the combustion chamber 10 toward the edge of the combustion chamber 10; wherein, at least a portion of the first contour surface 11 is arranged parallel to the plane where the first oil film is located, thereby ensuring that the first contour surface 11 and the first oil film 210 achieve optimal parallel fit, preventing the first contour surface 11 from interfering with fuel injection, effectively preventing oil from accumulating on the bottom inner surface of the combustion chamber 10, reducing the thermal load on the piston pin, and improving the reliability of the high compression ratio combustion system.

[0043] Key dimensions H1, L1, and ∠A were optimized based on the spatial position of the fuel beam, minimizing the volumetric contribution of this area while ensuring the fuel does not impact the wall. The arc structure was optimized based on the flow field characteristics of 3D simulations to enhance oil-gas rotation, promote mixing, and improve reliability. Height H2 was adjusted to align the upper and lower volume distribution of the combustion chamber with the injector cone angle. The oil baffle structure ensures rapid diffusion of the fuel beam after it impacts the cylinder head, while minimizing fuel diffusion toward the cylinder liner, thereby improving reliability.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A combustion chamber structure, characterized in that: include: A combustion chamber (10), wherein an injector (101) is provided in the combustion chamber (10), wherein the injector (101) is used to inject oil, wherein the injected oil forms a first oil film and a second oil film, wherein the first oil film is closer to the bottom of the combustion chamber (10) than the second oil film; A first contour surface (11) is disposed in the combustion chamber (10), wherein the first contour surface (11) extends from the middle of the combustion chamber (10) toward the edge of the combustion chamber (10); Wherein, at least a portion of the first contour surface (11) is arranged parallel to the plane where the first oil film is located.

2. The combustion chamber structure according to claim 1, characterized in that: The angle between the first oil film and the second oil film is B, an intermediate film body is provided between the first oil film and the second oil film, the angle between the intermediate film body and the first oil film or the second oil film is half of the angle B, the angle between the intermediate film body and the center line of the combustion chamber (10) is C, and the angle between the first contour surface (11) and the center line of the combustion chamber (10) is A; ∠A=∠C-∠B / 2(∠C>∠A>∠B).

3. The combustion chamber structure according to claim 1, characterized in that: The combustion chamber structure further comprises: a second contour surface (12), at least a portion of the second contour surface (12) being opposite to the injector (101), and the second contour surface (12) being connected to the first contour surface (11); a chamber top surface (13), the fuel injector (101) being arranged on the chamber top surface (13), and the fuel injector (101) extending from the chamber top surface (13) toward the second contour surface (12) to a height H; The vertical distance between the chamber top surface (13) and the second contour surface (12) is H1, H1=H+(1mm-2mm).

4. The combustion chamber structure according to claim 3, characterized in that: The width of the second contour surface (12) is L1, L1 ranges from 1.5mm to 3mm.

5. The combustion chamber structure according to claim 3, characterized in that: The combustion chamber structure further comprises: A third contour surface (14) is connected to a side of the first contour surface (11) close to the edge of the combustion chamber (10), at least a portion of the third contour surface (14) is an arc-shaped surface, and the third contour surface (14) is used to block the oil.

6. The combustion chamber structure according to claim 5, characterized in that: The third contour surface (14) comprises: A first connecting segment surface (141), a second connecting segment surface (142), a third connecting segment surface (143) and a fourth connecting segment surface (144) connected in sequence, wherein one end of the first connecting segment surface (141) away from the second connecting segment surface (142) is connected to the second contour surface (12), the first connecting segment surface (141) is a first arcuate surface, the second connecting segment surface (142) is a second arcuate surface, the third connecting segment surface (143) is a third arcuate surface, and the fourth connecting segment surface (144) is a fourth arcuate surface; The radius of the arc where the first arc-shaped surface is located is R1, and R1 is 1mm to 1.5mm; The radius of the arc where the second arc-shaped surface is located is R2, and R2 is 8mm to 15mm; The radius of the arc where the third arc-shaped surface is located is R3, and R3 is 12mm to 18mm; The radius of the arc where the fourth arc-shaped surface is located is R4, and R4 is 3mm to 6mm.

7. The combustion chamber structure according to claim 5, characterized in that: The combustion chamber structure further comprises: a fourth contour surface (15), one end of the fourth contour surface (15) being connected to the third contour surface (14), and the other end of the fourth contour surface (15) being connected to the side wall of the combustion chamber (10); The fourth contour surface (15) extends in a horizontal direction, and the maximum vertical distance between the fourth contour surface (15) and the third contour surface (14) is H2; H2 is 3mm to 5mm.

8. The combustion chamber structure according to claim 5, characterized in that: The combustion chamber structure further comprises: a fifth contour surface (16), wherein two ends of the fifth contour surface (16) are respectively connected to the first contour surface (11) and the third contour surface (14); The fifth contour surface (16) includes a convex surface (160), the convex surface (160) protrudes in a direction close to the fuel injector (101), and the convex surface (160) is opposite to the nozzle of the fuel injector (101).

9. The combustion chamber structure according to claim 8, characterized in that: The fifth contour surface (16) further comprises: a fifth connecting surface segment (161) and a sixth connecting surface segment (162), wherein two ends of the fifth connecting surface segment (161) are respectively connected to the first contour surface (11) and the convex surface (160), and two ends of the sixth connecting surface segment (162) are respectively connected to the convex surface (160) and the third contour surface (14); The fifth connecting surface segment (161) and the sixth connecting surface segment (162) are respectively arc-shaped surfaces.

10. An engine comprising an engine body and a combustion chamber structure, wherein the combustion chamber structure is arranged in the engine body, characterized in that: The combustion chamber structure is the combustion chamber structure according to any one of claims 1 to 9.

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