Ignition of a compression-ignition gasoline engine piston and engine

Abstract

The application provides a kind of ignition compression gasoline engine piston and engine, the ignition compression gasoline engine piston includes: piston body, the top surface of the piston body is provided with pit, first intake valve avoidance pit, second intake valve avoidance pit, first exhaust valve avoidance pit and second exhaust valve avoidance pit;Wherein, the center of the pit is offset to the back along the first direction relative to the center of the piston body, the first direction is the front-back direction of engine, the first intake valve avoidance pit, second intake valve avoidance pit, first exhaust valve avoidance pit and second exhaust valve avoidance pit are sequentially arranged along the circumference of the pit;The long axis of the pit is in the first direction and perpendicular to the direction of intake and exhaust, and the short axis of the pit is in the direction of intake and exhaust.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engine, more particularly, relates to a kind of spark compression ignition gasoline engine piston and engine. BACKGROUND

[0002] In the engine spark compression ignition mode, to meet the needs of spark compression ignition, the top center of the piston is provided with a pit, and a first intake avoidance pit and a second intake avoidance pit, a first exhaust avoidance pit and a second exhaust avoidance pit are sequentially arranged around the pit. In actual use, the compression ignition combustion ratio is prone to decrease, and the engine thermal efficiency and emission level are not ideal. SUMMARY

[0003] Therefore, the present application provides a kind of spark compression ignition gasoline engine piston and engine to solve the technical problem of how to improve the compression ignition combustion ratio.

[0004] The technical scheme of the present application is as follows:

[0005] The present application provides a kind of spark compression ignition gasoline engine piston, comprising:

[0006] The top surface of the piston body is provided with a pit, a first intake valve avoidance pit, a second intake valve avoidance pit, a first exhaust valve avoidance pit and a second exhaust valve avoidance pit;Wherein, the center of the pit is offsetly arranged along the first direction to the rear relative to the center of the piston body, the first direction is the front-rear direction of the engine, and the first intake valve avoidance pit, the second intake valve avoidance pit, the first exhaust valve avoidance pit and the second exhaust valve avoidance pit are sequentially arranged along the circumference of the pit;The long axis of the pit is located in the first direction and perpendicular to the intake and exhaust direction, and the short axis of the pit is in the intake and exhaust direction.

[0007] In some embodiments, the length of the cross section of the pit increases from front to back along the first direction.

[0008] In some embodiments, the pit is symmetrically arranged in the intake and exhaust direction.

[0009] In some embodiments, the long axis of the pit is 30%-40% of the diameter of the piston body, and the short axis of the pit is less than or equal to 28% of the diameter of the piston body.

[0010] In some embodiments, the depth of the pit is greater than or equal to 5mm.

[0011] In some embodiments, the pit includes a bottom surface and a side surface arranged around the bottom surface, the center of the bottom surface is offsetly arranged along the first direction to the rear relative to the center of the piston body, and the side surface is connected with the first intake valve avoidance pit, the second intake valve avoidance pit, the first exhaust valve avoidance pit and the second exhaust valve avoidance pit.

[0012] In some embodiments, a first top surface is provided between the first exhaust valve clearance pit and the second exhaust valve clearance pit, a second top surface is provided between the first intake valve clearance pit and the second intake valve clearance pit, a third top surface is provided between the first intake valve clearance pit and the first exhaust valve clearance pit, and a fourth top surface is provided between the second intake valve clearance pit and the second exhaust valve clearance pit, wherein the first top surface, the second top surface, the third top surface and the fourth top surface are at the same height.

[0013] In some embodiments, both the first intake valve clearance recess and the first exhaust valve clearance recess are smoothly connected to the first top surface.

[0014] This invention provides an engine, comprising:

[0015] The piston of the compression ignition gasoline engine.

[0016] In some embodiments, it also includes:

[0017] The spark plug is positioned opposite to the center of the top surface of the piston body;

[0018] The injector has an axis extending in the direction of intersection with the long axis of the recess, and the injector is positioned at the rear end of the spark plug in the first direction.

[0019] This invention provides a piston and engine for a combustion-ignition compression-ignition gasoline engine. The piston includes a piston body with a recess on its top surface, and a first intake valve clearance recess, a second intake valve clearance recess, a first exhaust valve clearance recess, and a second exhaust valve clearance recess arranged around the recess. The center of the recess is offset rearward relative to the center of the piston body along a first direction, which is the engine's longitudinal direction. By setting the center of the recess eccentrically relative to the center of the piston body, this invention alters the flow field distribution of the gas-fuel mixture vortex and reduces the risk of fuel jets spraying out of the recess. This reduces the impact on the gas-fuel mixture concentration distribution, concentrates the gas-fuel mixture concentration, improves ignition efficiency, increases the compression ignition ratio, optimizes the combustion process, and enhances thermal efficiency. Attached Figure Description

[0020] Figure 1 This is a top view of the piston body according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the engine structure according to an embodiment of the present invention;

[0022] Figure 3 This describes the distribution of the mixed gas in the combustion chamber 20°CA before the top dead center of the compression in the combustion system of this embodiment of the invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Piston body; 2. Top surface; 21. First top surface; 22. Second top surface; 23. Third top surface; 24. Fourth top surface; 3. Recess; 31. Bottom surface; 32. Side surface; 4. First intake valve clearance recess; 5. Second intake valve clearance recess; 6. First exhaust valve clearance recess; 7. Second exhaust valve clearance recess; 8. Spark plug; 9. Injector. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. The various specific technical features described in the specific embodiments can be combined in any suitable manner without contradiction; for example, different combinations of specific technical features can form different embodiments and technical solutions. To avoid unnecessary repetition, various possible combinations of the various specific technical features in this invention will not be described separately.

[0026] In the following description, the terms "first," "second," etc., are used merely to distinguish different objects and do not indicate that the objects have the sameness or relationship. It should be understood that the directional descriptions "above," "below," "outside," and "inside" refer to the orientation under normal use conditions, while "left" and "right" refer to the left and right directions shown in the corresponding diagrams, which may or may not be the left and right directions under normal use conditions.

[0027] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. "A plurality of" means two or more.

[0028] The spark-ignition compression ignition gasoline engine piston provided in this embodiment of the invention can be applied to any type of vehicle engine. For example, the engine can be applied to a passenger car, and for example, the engine can also be applied to a truck. It should be noted that the environment in which the spark-ignition compression ignition gasoline engine piston in this embodiment of the invention is applied will not limit the structure of the spark-ignition compression ignition gasoline engine piston.

[0029] Hybrid vehicles or pure gasoline-powered vehicles all have at least one internal combustion engine. An internal combustion engine is a device that converts the internal energy of fuel into the kinetic energy of a piston by forcing fuel into a cylinder and violently burning the fuel-air mixture inside the cylinder. Some types of engines are equipped with spark plugs, which provide ignition energy so that the spark plug can ignite at least a portion of the fuel-air mixture entering the cylinder according to the combustion mode requirements.

[0030] This invention provides a piston for an ignition compression ignition gasoline engine, such as... Figure 1 As shown, the piston of an ignition compression ignition gasoline engine includes a piston body 1. The top surface 2 of the piston body 1 is provided with a recess 3, a first intake valve clearance recess 4, a second intake valve clearance recess 5, a first exhaust valve clearance recess 6, and a second exhaust valve clearance recess 7. The center a of the recess 3 is offset rearward relative to the center b of the piston body 1 along a first direction. It should be noted that the cross-section of the piston body 1 is approximately circular, and the center b of the piston body 1 is located at the center of the cross-section. In this embodiment, the cross-section of the recess 3 is set to an irregular shape. The center of the recess 3 can be understood as the geometric center of the cross-section of the recess 3. In this embodiment, the center a of the recess 3 does not coincide with the center b of the piston body 1, and the center a of the recess 3 is offset rearward relative to the center b of the piston body 1. In this embodiment, the first direction is defined as the engine's longitudinal direction. Figure 1 The direction indicated by the middle arrow is the front of the engine, and the direction opposite to the arrow is the rear of the engine (the direction of the arrow line is the first direction). The center a of the recess 3 and the center b of the piston body 1 are both located in the first direction. The direction forward of the center b of the piston body 1 in the first direction is the front of the engine, and the direction backward of the center b of the piston body 1 in the first direction is the rear of the engine. The center a of the recess 3 is offset backward relative to the center b of the piston body 1 in the first direction. Furthermore, the center b of the piston body 1 can be located within the recess 3.

[0031] like Figure 1As shown, in this embodiment of the invention, the first intake valve clearance pit 4, the second intake valve clearance pit 5, the first exhaust valve clearance pit 6, and the second exhaust valve clearance pit 7 are arranged sequentially along the circumference of the recess 3. By arranging the first intake valve clearance pit 4, the second intake valve clearance pit 5, the first exhaust valve clearance pit 6, and the second exhaust valve clearance pit 7 along the circumference of the recess 3, during the intake and compression strokes of the engine, the air resistance of the fuel and air entering the piston body 1 during the first injection at the bottom surface of the recess 3 is reduced, resulting in a more uniform mixture of fuel and air. Simultaneously, during engine combustion, the first intake valve clearance pit 4 and the second intake valve clearance pit 5 reduce the flow resistance of the flame within the recess, allowing the flame to spread more smoothly throughout the combustion chamber. This results in higher combustion synchronicity of the lean-air mixture surrounding the flame core within the combustion chamber, further improving the combustion efficiency of the compression ignition engine. The first exhaust valve clearance pit 6 and the second exhaust valve clearance pit 7 allow the portion of the piston body on the exhaust side away from the recess to accommodate more combustion exhaust gas after combustion. This area is connected to the exhaust pipe, so that the combustion exhaust gas generated after combustion can be more easily discharged from the cylinder, further improving the combustion efficiency of the engine.

[0032] like Figure 1 As shown, in this embodiment of the invention, the major axis of the recess 3 is located in the first direction and perpendicular to the intake and exhaust direction, while the minor axis of the recess 3 is in the intake and exhaust direction. It should be noted that the major axis of the recess 3 represents the longest line segment obtained by connecting two points on the cross-section of the recess 3. The minor axis of the recess 3 represents the shortest line segment obtained by connecting two points on the cross-section of the recess 3. In this embodiment of the invention, the major axis of the recess 3 is in the engine's longitudinal direction, and the minor axis of the recess 3 is in a direction perpendicular to the engine's longitudinal direction.

[0033] When the engine's combustion mode is spark-compression ignition, the injector needs to inject fuel twice. The first injection occurs during the intake stroke to create a lean air-fuel mixture in the cylinder. Specifically, the injector injects a small amount of fuel into the cylinder during the intake stroke, which mixes with the air flowing into the cylinder through the intake manifold, resulting in a low-concentration air-fuel mixture. The second injection occurs during the compression stroke, injecting fuel into the central recess on the piston crown when the piston reaches a predetermined height. This creates a locally enriched air-fuel mixture in the central recess. As the piston continues to move near top dead center, the engine's ignition system ignites the locally enriched air-fuel mixture in the central recess, forming a flame core. This flame core heats the surrounding lean air-fuel mixture, and the piston continues to compress it, causing the surrounding lean air-fuel mixture to ignite under the combined action of the flame core's heating and the piston's compression.

[0034] In this embodiment of the invention, the mixed gas has initial momentum before entering the top surface 2 of the piston body 1. After reaching the top surface 2 of the piston body 1, it forms a circulating mixed gas vortex. This embodiment of the invention improves the top structure of the piston body 1 by offsetting the center of the recess 3 relative to the center of the piston body 1, and by offsetting the center of the recess 3 along the long axis towards the rear end of the engine. This can disturb the flow field, change the flow field distribution of the mixed gas vortex, thereby optimizing the ignition and compression ignition processes in the combustion system. Furthermore, the eccentrically positioned recess helps reduce the risk of fuel jets spraying outside the recess, thus reducing the impact on the mixed gas concentration distribution, which in turn helps to increase the compression ignition ratio, optimize the combustion process, and improve thermal efficiency.

[0035] This invention provides a piston for a combustion engine with ignition compression ignition. The piston includes a piston body with a recess on its top surface, and a first intake valve clearance recess, a second intake valve clearance recess, a first exhaust valve clearance recess, and a second exhaust valve clearance recess arranged around the recess. The center of the recess is offset rearward relative to the center of the piston body in a first direction, which is the longitudinal direction of the engine. By setting the center of the recess eccentrically relative to the center of the piston body, this invention changes the flow field distribution of the gas-fuel mixture vortex and reduces the risk of fuel jets spraying out of the recess. This reduces the impact on the gas-fuel mixture concentration distribution and helps to concentrate the gas-fuel mixture concentration, improve ignition efficiency, increase the compression ignition ratio, optimize the combustion process, and improve thermal efficiency.

[0036] In some embodiments, such as Figure 1 As shown, the cross-section of the recess 3 increases in length from front to back along the first direction. It should be noted that the cross-section of the recess 3 is perpendicular to the direction of movement of the piston body 1. The length of the recess 3 cross-section can be understood as the distance between two points on the edge formed by the side of the recess 3. The length of the recess 3 increases from front to back along the first direction. By setting the recess cross-section to increase in length from front to back along the first direction, this embodiment of the invention helps to change the flow field distribution of the mixed gas vortex. This reduces the risk of fuel jets spraying out of the recess and concentrates the concentration of the mixed gas within the formed vortex flow field, thereby increasing the compression ignition ratio and thus improving thermal efficiency.

[0037] In some embodiments, such as Figure 1 As shown, the recesses 3 are symmetrically arranged in the intake and exhaust directions. In this embodiment of the invention, the intake and exhaust directions are perpendicular to the first direction. By symmetrically arranging the recesses 3 in the intake and exhaust directions, this embodiment of the invention helps to concentrate the flow field distribution of the mixed gas vortex on the long axis of the recesses 3, thereby helping to concentrate the concentration of the mixed gas and further improve the compression ignition ratio.

[0038] In some embodiments, such as Figure 1 As shown, in this embodiment of the invention, the major axis L1 of the recess 3 is 30%-40% of the diameter L3 of the piston body 1, and the minor axis L2 of the recess 3 is less than or equal to 28% of the diameter L3 of the piston body 1. The piston body 1 has a roughly circular cross-section, and the diameter L3 of the piston body 1 can be understood as the diameter of the cross-section. The major axis L1 of the recess 3 is the distance between the two farthest points of the recess 3 in the first direction, and the minor axis L2 of the recess 3 is the distance between the two farthest points of the recess 3 in the intake and exhaust directions. By limiting the major axis of the recess 3 to 30%-40% of the piston body 1 and the minor axis of the recess 3 to less than or equal to 28% of the diameter of the piston body 1, this embodiment of the invention, by limiting the cross-sectional area of ​​the recess 3 to a set value, or by limiting the ratio of the cross-sectional area of ​​the recess 3 to the cross-sectional area of ​​the piston body 1 within a certain range, facilitates the concentration of the mixed gas concentration and better concentrates the vortex at the center of the recess, thereby improving ignition efficiency.

[0039] In some embodiments, combined with Figure 1 and Figure 2 As shown, the depth of the recess 3 is ≥5mm. Here, the depth of the recess 3 represents the distance from its top to its bottom. In this embodiment of the invention, by setting the depth of the recess 3 to be greater than or equal to a set value, the recess 3 has sufficient space to accommodate the gas mixture, thereby facilitating the formation of a higher concentration of the gas mixture within the vortex flow field, which is more conducive to improving ignition efficiency. In some embodiments, the depth of the recess 3 can be set to 5.5mm, 6mm, 6.3mm, etc. Setting the depth of the recess 3 to a set value in this embodiment of the invention facilitates the formation of a concentrated vortex flow within the recess, thereby improving ignition efficiency.

[0040] In some embodiments, such as Figure 1 and Figure 2 As shown, the recess 3 includes a bottom surface 31 and a side surface 32 surrounding the bottom surface 31. The center of the bottom surface 31 is offset rearward relative to the center of the piston body 1 in a first direction. The line connecting the center of the bottom surface 31 and the center of the recess 3 is perpendicular to the cross-section of the recess 3. That is, the center of the bottom surface 31 can be projected vertically onto the center of the recess 3. Figure 1 and Figure 2As shown, the side surface 32 of the recess 3 surrounds the bottom surface 31 to form an internal cavity. The side surface 32 connects with the first intake valve clearance recess 4, the second intake valve clearance recess 5, the first exhaust valve clearance recess 6, and the second exhaust valve clearance recess 7. In this embodiment of the invention, by connecting the side surface 32 with the four peripheral recesses, the first intake valve clearance recess 4 and the second intake valve clearance recess 5 on the periphery can smoothly guide the air-fuel mixture into the recess, and the first exhaust valve clearance recess 6 and the second exhaust valve clearance recess 7 can more easily expel exhaust gas from the cylinder, further improving the engine's combustion efficiency.

[0041] In some embodiments, such as Figure 1 As shown, a first top surface 21 is provided between the first exhaust valve clearance pit 6 and the second exhaust valve clearance pit 7, a second top surface 22 is provided between the first intake valve clearance pit 4 and the second intake valve clearance pit 5, a third top surface 23 is provided between the first intake valve clearance pit 4 and the first exhaust valve clearance pit 6, and a fourth top surface 24 is provided between the second intake valve clearance pit 5 and the second exhaust valve clearance pit 7. The first top surface 21, the second top surface 22, the third top surface 23 and the fourth top surface 24 are of the same height. The term "equal height" indicates that the distances from the first top surface 21, the second top surface 22, the third top surface 23, and the fourth top surface 24 to the bottom surface 31 of the pit 3 are equal. In this embodiment of the invention, the four top surfaces are set at equal heights, and the pit 3 is connected to the first top surface 21, the second top surface 22, the third top surface 23, and the fourth top surface 24 by a circular arc transition. This helps to reduce the flow resistance of the oil-gas mixture and the resistance to flame propagation. The pit 3 on the piston top surface of the compression ignition engine provided in this embodiment concentrates the second injected fuel in the center a of the pit 3, thereby forming a locally enriched oil-gas mixture in the pit 3. The pit 3 is relatively deep, which helps to concentrate the concentration of the mixed gas and improve the ignition efficiency.

[0042] In some embodiments, such as Figure 1 and Figure 2 As shown, both the first intake valve clearance recess 4 and the first exhaust valve clearance recess 6 are smoothly connected to the first top surface 21. It should be noted that, in this embodiment of the invention, by tilting and filling the surface of the first intake valve clearance recess 4 towards the first exhaust valve clearance recess 6, and by tilting and filling the surface of the first exhaust valve clearance recess 6 towards the first intake valve clearance recess 4, the surface area of ​​the first top surface 21 can be minimized while reducing gas flow resistance. This reduces the combustion chamber volume, increases the compression ratio, and improves the combustion efficiency of the gasoline engine.

[0043] This invention provides an engine, such as... Figure 2As shown, the engine includes a piston for a gasoline engine with ignition compression ignition. In this embodiment, the piston body has a recess on its top surface, and a first intake valve clearance recess, a second intake valve clearance recess, a first exhaust valve clearance recess, and a second exhaust valve clearance recess are arranged around the recess. The center of the recess is offset rearward relative to the center of the piston body along a first direction, which is the engine's longitudinal direction. By setting the center of the recess eccentrically relative to the center of the piston body, this embodiment alters the flow field distribution of the gas-fuel mixture vortex and reduces the risk of fuel jetting outside the recess. This reduces the impact on the gas-fuel mixture concentration distribution, concentrates the gas-fuel mixture concentration, improves ignition efficiency, increases the compression ignition ratio, optimizes the combustion process, and enhances thermal efficiency.

[0044] In some embodiments, such as Figure 2 As shown, the engine in this embodiment of the invention also includes a spark plug 8 and a fuel injector 9. The spark plug 8 is positioned opposite the center of the top surface 2 of the piston body 1; the axis of extension of the fuel injector 9 intersects the long axis of the recess 3, and the fuel injector 9 is positioned at the rear end of the spark plug 8 in the first direction. By eccentrically positioning the fuel injector 9 relative to the top surface of the piston body 1, this embodiment of the invention allows the fuel injector 9 to directly inject fuel into the recess 3, reducing the risk of fuel jet spraying out of the recess, thereby further reducing the impact on the mixture concentration distribution. The end of the spark plug 8 used for outputting the electric spark is adjacent to the recess 3. The spark plug 8 is opposite to the center of the piston body 1 and also faces the recess. It can output an electric spark into the recess to ignite at least part of the fuel and air mixture in the recess, while also providing space for the fuel injector 9, reducing the risk of fuel jet spraying out of the recess. This concentrates the mixture concentration, improving ignition efficiency and compression ignition ratio, optimizing the combustion process, and improving thermal efficiency.

[0045] Figure 3 The diagram shows a combustion simulation of a piston in a ignition-compression ignition gasoline engine according to an embodiment of the present invention. This embodiment creates a one-dimensional performance simulation model of the target ignition-compression ignition engine based on the piston's geometric feature parameters. These parameters include: piston shape parameters; initial combustion parameter values ​​are determined based on the basic feature parameters of the target ignition-compression ignition engine; the combustion parameters include the ignition timing corresponding to the turbulent flame model; the initial combustion parameter values ​​are applied to the simulation model to obtain initial engine performance parameters; the combustion parameters are corrected according to the initial engine performance parameters and a preset cylinder pressure threshold to obtain target combustion parameter values; and the target combustion parameter values ​​are applied to the one-dimensional performance simulation model to obtain performance prediction data for the ignition-compression ignition engine.

[0046] Specifically, Figure 3This describes the distribution of the gas mixture in the combustion chamber 20°CA before the top dead center of the compression in the combustion system provided in this embodiment of the invention. A richer gas mixture can be formed on the surface of the piston body near the spark plug 8. Therefore, the structure of the piston body in this embodiment of the invention can improve ignition efficiency and flame propagation efficiency, thereby benefiting combustion efficiency and the thermal efficiency of the gasoline engine.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A piston for an ignition compression ignition gasoline engine, characterized in that, include: The piston body has a recess, a first intake valve clearance recess, a second intake valve clearance recess, a first exhaust valve clearance recess, and a second exhaust valve clearance recess on its top surface. The center of the recess is offset rearward relative to the center of the piston body along a first direction, which is the engine's longitudinal direction. The first intake valve clearance recess, the second intake valve clearance recess, the first exhaust valve clearance recess, and the second exhaust valve clearance recess are arranged sequentially along the circumference of the recess. The major axis of the recess is located in the first direction and perpendicular to the intake and exhaust directions, while the minor axis of the recess is in the intake and exhaust directions. The center of the piston body is located in the recess, the major axis of the recess is 30%-40% of the diameter of the piston body, and the minor axis of the recess is less than or equal to 28% of the diameter of the piston body.

2. The piston for an ignition compression ignition gasoline engine according to claim 1, characterized in that, The cross-section of the pit increases in length from front to back along the first direction.

3. The piston for an ignition compression ignition gasoline engine according to claim 2, characterized in that, The recesses are symmetrically arranged in the air intake and exhaust directions.

4. The piston of a gasoline engine with ignition compression ignition according to claim 1, characterized in that, The depth of the pit is ≥5mm.

5. The piston for an ignition compression ignition gasoline engine according to claim 1, characterized in that, The recess includes a bottom surface and a side surface surrounding the bottom surface. The center of the bottom surface is offset rearward relative to the center of the piston body along the first direction. The side surface is connected to the first intake valve clearance recess, the second intake valve clearance recess, the first exhaust valve clearance recess, and the second exhaust valve clearance recess.

6. The piston of a gasoline engine with ignition compression ignition according to claim 1, characterized in that, A first top surface is provided between the first exhaust valve clearance pit and the second exhaust valve clearance pit, a second top surface is provided between the first intake valve clearance pit and the second intake valve clearance pit, a third top surface is provided between the first intake valve clearance pit and the first exhaust valve clearance pit, and a fourth top surface is provided between the second intake valve clearance pit and the second exhaust valve clearance pit, wherein the first top surface, the second top surface, the third top surface and the fourth top surface are of the same height.

7. The piston for an ignition compression ignition gasoline engine according to claim 6, characterized in that, Both the first intake valve clearance recess and the first exhaust valve clearance recess are smoothly connected to the first top surface.

8. An engine, characterized in that, include: The ignition compression ignition gasoline engine piston according to any one of claims 1-7.

9. The engine according to claim 8, characterized in that, Also includes: The spark plug is positioned opposite to the center of the top surface of the piston body; The injector has an axis extending in the direction of intersection with the long axis of the recess, and the injector is positioned at the rear end of the spark plug in the first direction.

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