Engine

Abstract

The utility model provides an engine which comprises an air cylinder, a piston and a cylinder cover, the piston is movably arranged in the air cylinder, and a protruding part gradually protruding inwards in the radial direction is formed on the edge of the top of the piston. The cylinder cover is installed on the cylinder, a combustion chamber is defined by the cylinder cover, the cylinder and the piston, a matching part surrounding the combustion chamber is formed on the surface, facing the combustion chamber, of the cylinder cover, and the protruding part is configured to respond to the piston to move upwards to the upper dead center to be in clearance fit with the matching part.

Description

Technical Field

[0001] This utility model relates to the field of engine structure technology, and in particular to an engine. Background Technology

[0002] An engine is a thermodynamic machine that converts the chemical energy of fuel into mechanical energy, and it is widely used in automobiles, ships, aviation, and other fields. Its core working principle is to generate high-temperature, high-pressure gas by burning fuel, which drives the piston, thereby rotating the crankshaft to output power. Based on the different working cycles, engines can be divided into four-stroke engines and two-stroke engines; based on the different ignition methods, they can be divided into spark-ignition engines (such as gasoline engines) and compression-ignition engines (such as diesel engines).

[0003] Compression ratio is a crucial parameter in engine design and performance optimization. It is the ratio of the cylinder volume (total volume) when the piston is at bottom dead center to the cylinder volume (combustion chamber volume) when the piston is at top dead center. Compression ratio directly affects engine thermal efficiency, power performance, and emissions characteristics. A higher compression ratio can improve fuel combustion efficiency, increase engine output power, and reduce fuel consumption. However, an excessively high compression ratio can also lead to knocking, especially in gasoline engines, which can damage engine components and reduce their reliability. Therefore, engine design needs to find the optimal balance between compression ratio, fuel type, and combustion stability.

[0004] In related technologies, the compression ratio of gasoline engines is typically 10-12, with a thermal efficiency of approximately 36%. To further improve thermal efficiency, the compression ratio needs to be increased to 15 or even higher. However, with the engine displacement remaining constant, increasing the compression ratio requires reducing the combustion chamber volume. Furthermore, not all areas of the combustion chamber can achieve complete combustion. When the piston reaches top dead center, the combustion flame cannot spread to the narrow gap between the piston crown and the cylinder head. This results in a larger proportion of the narrow gap area when the combustion chamber volume is reduced, leading to a lack of significant improvement in overall combustion efficiency and increased emissions. Therefore, how to provide an engine that can further increase the compression ratio while reducing the negative impact on combustion efficiency and emissions has become an urgent technical problem to be solved. Utility Model Content

[0005] In view of this, the present invention provides an engine that can effectively reduce the gap between the piston and the cylinder head at top dead center, reduce the incompleteness caused by the gap, and facilitate further improvement of the engine's compression ratio.

[0006] To achieve the above objectives, this utility model provides an engine comprising: a cylinder; a piston movably disposed within the cylinder, the piston having a protrusion that gradually bulges inward in a radial direction at its top edge; and a cylinder head mounted on the cylinder and defining a combustion chamber with the cylinder and the piston; wherein the surface of the cylinder head facing the combustion chamber has a mating portion surrounding the combustion chamber, and the protrusion is configured to form a clearance fit with the mating portion in response to the piston moving upward to top dead center.

[0007] In one exemplary embodiment, the mating portion is configured to gradually recess inward in the radial direction from the surface edge of the cylinder head toward the combustion chamber, so as to form a clearance fit with the protrusion of the protrusion.

[0008] In one exemplary embodiment, the mating space defined by the mating portion is constructed as a frustum-shaped space.

[0009] In one exemplary embodiment, the cross-section of the frustum-shaped space is trapezoidal, and the included angle between the two sides of the trapezoidal cross-section is an obtuse angle.

[0010] In one exemplary embodiment, two protrusions are formed and spaced apart in the circumferential direction, and a flat top coplanar with the top of the piston is formed between the two protrusions.

[0011] In one exemplary embodiment, the two protrusions are arranged at both ends of the piston top in the radial direction.

[0012] In one exemplary embodiment, a recess is also formed at the center of the piston top, which is suitable for guiding the airflow in the combustion chamber to form a planar vortex.

[0013] In one exemplary embodiment, the surface roughness of the protrusion and / or the mating part is less than or equal to Ra3.2.

[0014] In one exemplary embodiment, the distance between the protrusion and the mating part when they form a clearance fit is d, and 0.5mm≤d≤1mm.

[0015] The engine provided by this utility model has a mating part on the side of the cylinder head facing the combustion chamber, that is, the bottom surface of the cylinder head, which matches the protrusion on the top of the piston. When the piston runs to the top dead center, the protrusion can form a clearance fit with the mating part. This clearance fit effectively prevents or reduces the incomplete combustion of the air-fuel mixture while ensuring that the piston and the cylinder head do not collide. As a result, when the compression ratio is increased without changing the engine displacement, the emissions of pollutants are reduced and the combustion efficiency can be effectively improved. Attached Figure Description

[0016] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 This is a cross-sectional schematic diagram of the engine provided by this utility model, showing the cylinder, piston and cylinder head;

[0018] Figure 2 yes Figure 1 A magnified view of a portion of the image;

[0019] Figure 3 yes Figure 1 A schematic diagram of the cylinder head surface facing the combustion chamber side in the exemplary embodiment shown;

[0020] Figure 4 This is a simplified structural diagram of the engine provided by this utility model;

[0021] Figure 5 This is a partial cross-sectional schematic diagram of the engine provided by this utility model;

[0022] Figure 6 yes Figure 1 A perspective view of the piston head in the exemplary embodiment shown;

[0023] Figure 7 yes Figure 1 The exemplary embodiment shown is a plan view of the piston.

[0024] The meanings of the reference numerals in the above figures are as follows:

[0025] 1. Cylinder;

[0026] 2. Piston;

[0027] 21. Protrusion;

[0028] 22. Flat top;

[0029] 23. Pits;

[0030] 3. Cylinder head;

[0031] 31. Coordination Department;

[0032] 4. Combustion chamber. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0035] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0036] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0037] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference in the accompanying drawings and are not intended to limit the scope of protection of this utility model. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this utility model.

[0038] Figure 1 This is a cross-sectional view of the engine provided by this utility model, showing the cylinder, piston, and cylinder head. Figure 2 yes Figure 1 A magnified view of a portion of the image. Figure 3 yes Figure 1 A schematic diagram of the cylinder head's surface facing the combustion chamber side, as shown in the exemplary embodiment. Figure 4 This is a simplified structural diagram of the engine provided by this utility model. Figure 5 This is a partial cross-sectional schematic diagram of the engine provided by this utility model.

[0039] An exemplary embodiment of this utility model provides an engine, such as Figures 1 to 4As shown, the system includes a cylinder 1, a piston 2, and a cylinder head 3. The piston 2 is movably arranged inside the cylinder 1, and a protrusion 21 that gradually rises inward in the radial direction is formed on the top edge of the piston 2. The cylinder head 3 is mounted on the cylinder 1 and defines a combustion chamber 4 with the cylinder 1 and the piston 2. The surface of the cylinder head 3 facing the combustion chamber 4 has a mating portion 31 surrounding the combustion chamber 4. The protrusion 21 is configured to form a clearance fit with the mating portion 31 in response to the piston 2 moving upward to top dead center.

[0040] In this implementation, when the piston 2 is at bottom dead center, the size of the first space enclosed by the top of the piston 2, the side wall of the cylinder 1, and the cylinder head 3 is the total volume of the cylinder. When the piston 2 reaches top dead center, the size of the second space enclosed by the top of the piston 2, the side wall of the cylinder 1, and the cylinder head 3 is the volume of the combustion chamber. At this time, the air-fuel mixture burns normally within the effective volume of the combustion chamber. However, the air-fuel mixture in the narrow gap between the top of the piston 2 and the cylinder head 3 cannot burn completely because the flame cannot spread. By providing a mating part 31 on the side of the cylinder head 3 facing the combustion chamber 4, that is, the bottom surface of the cylinder head 3, which matches the protrusion 21 on the top of the piston 2, the protrusion 21 can form a clearance fit with the mating part 31 when the piston 2 reaches top dead center. This clearance fit prevents or reduces the incomplete combustion of the air-fuel mixture while ensuring that the piston 2 and the cylinder head 3 do not collide. As a result, when the compression ratio is increased while the engine displacement remains unchanged, the emissions of pollutants are reduced and the combustion efficiency is effectively improved.

[0041] In one exemplary embodiment, such as Figures 2-3 As shown, the mating part 31 is configured to gradually recess inward in the radial direction from the surface edge of the cylinder head 3 toward the combustion chamber 4, so as to form a clearance fit with the protrusion of the protrusion 21.

[0042] In this embodiment, the protrusion 21 is a boss that rises inward from the edge of the top surface of the piston 2, and the side of the boss is inclined. The mating part 31 is recessed inward from the edge of the surface of the cylinder head 3 toward the combustion chamber 4. When the piston 2 moves to the top dead center, the boss moves upward with the piston 2 into the recessed part, so that the mating part 31 and the side of the boss form a clearance fit. The air-fuel mixture in the combustion chamber 4 is difficult to enter the gap, the incomplete combustion phenomenon is significantly reduced, emissions are reduced, and the negative impact on combustion efficiency is reduced.

[0043] According to embodiments of this disclosure, such as Figure 4 The mating space defined by the mating part 31 shown is constructed as a frustum-shaped space.

[0044] In this embodiment, the surface of the mating part 31 is also an annular inclined surface. In other words, the surfaces on which the mating part 31 and the protrusion 21 form a mating are both approximately a part of the side of a cone, or a conical surface. The conical surface of the mating part 31 defines a frustum-shaped space for accommodating the protrusion 21.

[0045] According to an embodiment of this disclosure, the cross-section of the frustum-shaped space is trapezoidal, and the included angle between the two legs of the trapezoidal cross-section is an obtuse angle.

[0046] In this embodiment, the cross-section of the frustum-shaped space along the piston axial direction is trapezoidal, and the two sides of the trapezoid are the clearance fit positions of the protrusion 21 and the mating part 31. By setting the included angle between the two sides to an obtuse angle, incomplete combustion is minimized, and the impact on airflow is also reduced.

[0047] For example, when the included angle is equal to 180°, an effective gap fit cannot be formed, or the gap is too large, and a considerable part of the mixture will still have incomplete combustion. When the included angle is less than or equal to 90°, although it will make it more difficult for the mixture to enter the gap, it will result in a higher bulge height of the protrusion 21, affecting the flow of the mixture in the combustion chamber 4, which will also have a negative impact on combustion efficiency.

[0048] Specifically, in Figure 4 The upper part is a simplified structural diagram of the engine, showing the protrusion 21 and the mating part 31. Figure 4 The central part is a magnified three-dimensional schematic diagram of the area indicated by the dashed line, showing the frustum-shaped space defined by the mating part 31. Figure 4 The lower part is a cross-sectional diagram of a frustum-shaped space, where the angle between the extensions of the two sides is an obtuse angle, for example... Figure 4 or Figure 5 The 160° shown in the figure.

[0049] Figure 6 yes Figure 1 In the exemplary embodiment shown, a perspective view of the piston head is provided. Figure 7 yes Figure 1 The exemplary embodiment shown is a plan view of the piston.

[0050] In one exemplary embodiment, such as Figures 6 to 7 As shown, there are two protrusions 21 that are spaced apart in the circumferential direction, and a flat top 22 that is coplanar with the top of the piston 2 is formed between the two protrusions 21.

[0051] In this implementation, the combination of the protrusion 21 and the flat top 22 optimizes the airflow motion, forming a larger-scale tumble flow. During the power stroke of the combustion chamber 4, the piston 2 compression process can break up the tumble flow and convert it into stronger turbulent kinetic energy, accelerating combustion and significantly improving the tendency to knock. This is beneficial for expanding the application scenarios of high compression ratio engines with large cylinder diameters.

[0052] More specifically, according to an embodiment of the present disclosure, two protrusions 21 are arranged at both ends of the piston 2 in the radial direction at the top of the piston 2.

[0053] In one exemplary embodiment, a recess 23 is also formed at the center of the top of the piston 2, which is suitable for guiding the airflow in the combustion chamber 4 to form a planar vortex.

[0054] In this embodiment, by simultaneously providing the protrusion 21 and the recess 23, the airflow speed during the intake stroke of the combustion chamber 4 is effectively increased, and the tumble intensity is enhanced. At the end of the compression phase of the combustion chamber 4, the protrusion 21 can break up the tumble flow and convert it into turbulent kinetic energy, thereby accelerating combustion and reducing the tendency for knocking.

[0055] In one exemplary embodiment, the surface roughness of the protrusion 21 and / or the mating portion 31 is less than or equal to Ra3.2.

[0056] In this implementation, by limiting the roughness to less than or equal to Ra3.2, microscopic defects on the surface can be reduced, corrosion resistance can be improved, and in-cylinder tumble flow can be facilitated, reducing flow resistance.

[0057] In one exemplary embodiment, the distance between the protrusion 21 and the mating part 31 when they form a clearance fit is d, and 0.5mm≤d≤1mm.

[0058] In this implementation, by limiting the value of 0.5mm≤d≤1mm, it is possible to ensure that the piston 2 and cylinder head 3 do not collide, and also to reduce the proportion of the slit area where incomplete combustion occurs, thereby reducing the negative impact on combustion efficiency and emissions when the compression ratio is increased.

[0059] For example, such as Figures 4 to 5 As shown, the frustum-shaped space defined by the mating part 31 has an included angle of 160° between the two waists of its trapezoidal cross section, and the mating gap between the protrusion 21 and the mating part 31 is about 0.7 mm. In this embodiment, the mixed gas is difficult to enter the 0.7 mm gap, and the protrusion 21 and the mating part 31 have high processing precision, small volume error, and small compression ratio deviation.

[0060] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the present invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the present invention, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. An engine characterized by, The application relates to a cylinder-piston assembly, comprising: a cylinder (1); a piston (2) movably arranged in the cylinder (1), a top edge of the piston (2) being formed with a convex portion (21) gradually bulging inward in a radial direction; and a cylinder head (3) mounted on the cylinder (1) and defining a combustion chamber (4) with the cylinder (1) and the piston (2); wherein a surface of the cylinder head (3) facing the combustion chamber (4) is formed with a matching portion (31) surrounding the combustion chamber (4), and the convex portion (21) is configured to form a clearance fit with the matching portion (31) in response to the piston (2) ascending to a top dead center.

2. The engine of claim 1, wherein The matching portion (31) is configured to gradually recess inward in a radial direction from an edge of the surface of the cylinder head (3) facing the combustion chamber (4) to form a clearance fit with the bulging of the convex portion (21).

3. The engine of claim 2, wherein, The matching space defined by the matching portion (31) is configured as a circular truncated cone space.

4. The engine of claim 3, wherein The cross section of the circular truncated cone space is a trapezoid, and the included angle between two waist sides of the trapezoid cross section is an obtuse angle.

5. The engine of any one of claims 1-4, wherein, The convex portion (21) is formed with two convex portions (21) spaced apart in a circumferential direction, and a flat top portion (22) is formed between the two convex portions (21) and coplanar with the top of the piston (2).

6. The engine of claim 5, wherein, The two convex portions (21) are arranged at two ends of the top of the piston (2) in a radial direction.

7. The engine of claim 5, wherein A dimple (23) is further formed at the center of the top of the piston (2) and is suitable for guiding the airflow in the combustion chamber (4) to form a planar vortex flow.

8. The engine of any one of claims 1-4, wherein, The surface roughness of the convex portion (21) and / or the surface roughness of the matching portion (31) is less than or equal to Ra3.

2.

9. The engine of any one of claims 1-4, wherein, The clearance between the convex portion (21) and the matching portion (31) is d, and 0.5mm<=d<=1mm.

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