Pistons and gas internal combustion engines

Abstract

This utility model relates to the field of engine technology, providing a piston and a gas internal combustion engine. The piston includes: a combustion chamber recess, including an intake-side recess and an exhaust-side recess. The intersection of the wall of the intake-side recess and the plane containing the central axis of the piston forms a first profile, which includes a maximum speed curve extending from the edge of the intake-side recess to its bottom. The wall of the exhaust-side recess is a smooth curved surface. A piston top surface surrounds the combustion chamber recess and connects to both the intake-side and exhaust-side recesses. The piston is adapted to be housed within a cylinder liner, one end of which is connected to a cylinder head. The cylinder liner, piston, and cylinder head form a combustion chamber. The cylinder head has an intake valve and an exhaust valve. The intake-side recess corresponds to the intake valve, and the exhaust-side recess corresponds to the exhaust valve. This piston can increase the average airflow velocity, reduce the piston surface temperature, and lower the risk of cylinder head cracks and knocking caused by high heat loads.

Description

Technical Field

[0001] This utility model relates to the field of engine technology, and in particular to a piston and gas internal combustion engine. Background Technology

[0002] As a highly efficient and clean power unit, the gas internal combustion engine has been widely used in distributed power generation, transportation, and other fields since its inception due to its fuel flexibility and low emissions. Its core component, the combustion chamber, is responsible for fuel mixing, ignition, combustion, and energy conversion; its design directly affects the overall engine's thermal efficiency and emissions performance. However, with the increase in power density and the diversification of fuels, the combustion chamber faces more severe thermal load challenges. In existing technologies, the high thermal load of gas internal combustion engines easily leads to thermal stress concentration in the cylinder head material, causing crack propagation and knocking, resulting in decreased reliability and economic losses, becoming a key bottleneck restricting further performance improvements. Utility Model Content

[0003] This invention provides a piston and a gas internal combustion engine to solve the problem that the high heat load of gas internal combustion engines in the prior art easily leads to cylinder head cracks and knocking.

[0004] This utility model provides a piston, comprising: The combustion chamber recess includes an intake-side recess and an exhaust-side recess. The intersection of the wall of the intake-side recess and the plane containing the central axis of the piston is a first profile. The first profile includes a maximum speed curve, which extends from the edge of the intake-side recess to the bottom of the intake-side recess. The wall of the exhaust-side recess is a smooth curved surface. The piston top surface surrounds the combustion chamber recess and is connected to the intake side recess and the exhaust side recess; The piston is adapted to be installed inside the cylinder liner, one end of the cylinder liner is connected to the cylinder head, the cylinder liner, the piston and the cylinder head surround to form a combustion chamber, the cylinder head is provided with an intake valve and an exhaust valve, the intake side recess corresponds to the intake valve and the exhaust side recess corresponds to the exhaust valve.

[0005] According to the piston provided by this utility model, the intersection line between the wall of the exhaust side recess and the plane where the central axis is located is a second profile line, and the second profile line is the same as the first profile line.

[0006] According to the present invention, the piston has a starting point at the end of the fastest curve closest to the top surface of the piston, and the tangent of the fastest curve at the starting point is parallel to the central axis.

[0007] According to the piston provided by this utility model, it further includes: The circular arc transition surface connects the intake-side recess and the exhaust-side recess to the piston top surface. The intersection of the circular arc transition surface and the plane containing the central axis is an arc line, which is tangent to the fastest curve at the starting point.

[0008] According to the present invention, the piston top surface is perpendicular to the central axis, and the distance between the starting point and the piston top surface in the axial direction of the piston is equal to the radius of the arc.

[0009] According to the present invention, the end of the fastest curve away from the top surface of the piston is the endpoint, and the tangent of the fastest curve at the endpoint is perpendicular to the central axis.

[0010] According to the present invention, the radius of the swing circle of the fastest curve is R, and the distance between the starting point of the fastest curve and the central axis of the piston is πR.

[0011] According to the present invention, the radius of the swing circle of the fastest curve is 0.07 to 0.15 times the piston diameter.

[0012] According to the present invention, a piston is provided on the top surface of the piston, with clearance pits corresponding to the positions of the intake valve and the exhaust valve.

[0013] This utility model also provides a gas internal combustion engine, including: a cylinder head, a cylinder liner, and any one of the above-mentioned pistons, wherein the piston is movably disposed within the cylinder liner, the cylinder head is connected to one end of the cylinder liner, and the cylinder liner, the piston, and the cylinder head surround to form a combustion chamber.

[0014] The piston and gas internal combustion engine provided by this utility model have an intake-side recess whose wall surface intersects the plane containing the central axis of the piston with a maximum speed curve. This maximum speed curve extends from the edge of the combustion chamber recess to the bottom of the combustion chamber recess. This shortens the time it takes for the airflow to reach the bottom of the combustion chamber recess along the wall surface during the intake process, increases the average airflow velocity, and thus helps to reduce the piston surface temperature, reducing the risk of cylinder head cracks and knocking caused by high heat load. It also helps to increase the intensity of in-cylinder turbulence and reduce in-cylinder gas turbulence dissipation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the piston provided by this utility model.

[0017] Figure 2 This is a cross-sectional view of the piston provided by this utility model.

[0018] Figure 3 This is a schematic diagram of the principle of the fastest curve provided by this utility model.

[0019] Figure 4 This is a schematic diagram comparing the structural features of combustion chamber pits based on the fastest curve and hemispherical combustion chamber pits.

[0020] Figure 5 This is a schematic diagram of the airflow movement in the combustion chamber of a gas internal combustion engine during the valve overlap period, provided by this utility model.

[0021] Figure 6 This is a schematic diagram of the airflow movement in the combustion chamber of a gas-fired internal combustion engine after the exhaust valve is completely closed, as provided by this utility model.

[0022] Figure 7 This is a schematic diagram of the airflow movement in the combustion chamber of a gas-fired internal combustion engine after the intake and exhaust valves are closed, as provided by this utility model.

[0023] Figure label: 100. Piston; 11. Combustion chamber recess; 111. Intake side recess; 112. Exhaust side recess; 12. Piston top surface; 13. Arc transition surface; 200. Cylinder head; 21. Intake valve; 22. Exhaust valve; 300. Cylinder liner. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] In the description of the embodiments of this utility model, it should be noted that, unless otherwise expressly specified and limited, the terms "first" and "second" are numbered for the purpose of clearly identifying product components and do not represent any substantial difference. The terms "installed," "connected," and "joined" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0026] The following is combined with Figures 1-7 This invention describes a piston and a gas internal combustion engine.

[0027] like Figure 1 and Figure 2 As shown, the piston 100 provided in this embodiment of the present invention includes a combustion chamber recess 11 and a piston top surface 12. The combustion chamber recess 11 includes an intake-side recess 111 and an exhaust-side recess 112. The intersection of the wall of the intake-side recess 111 and the plane containing the central axis A of the piston 100 is a first profile. The first profile includes a maximum speed curve, which extends from the edge of the intake-side recess 111 to the bottom of the intake-side recess 111. The wall of the exhaust-side recess 112 is a smooth curved surface. The piston top surface 12 surrounds the combustion chamber recess 11 and is connected to the intake-side recess 111 and the exhaust-side recess 112.

[0028] The piston 100 is adapted to be installed inside the cylinder liner 300. One end of the cylinder liner 300 is connected to the cylinder head 200. The cylinder liner 300, piston 100, and cylinder head 200 surround and form a combustion chamber. The cylinder head 200 is provided with an intake valve 21 and an exhaust valve 22. An intake-side recess 111 is provided corresponding to the intake valve 21, and an exhaust-side recess 112 is provided corresponding to the exhaust valve 22.

[0029] It is understandable that the intake valve 21 and the exhaust valve 22 are located on either side of the central axis A of the piston 100, see [reference]. Figure 5 Based on the positions of the intake valve 21 and the exhaust valve 22, the combustion chamber recess 11 is divided into an intake-side recess 111 and an exhaust-side recess 112, each representing half of the combustion chamber recess 11. When the intake valve 21 of the gas internal combustion engine is open, the gas entering the combustion chamber through the intake valve 21 moves along the wall of the intake-side recess 111 towards the bottom of the recess; when the exhaust valve 22 is open, the gas in the combustion chamber is discharged from the exhaust valve 22 along the wall of the exhaust-side recess 112.

[0030] In this design, the plane containing the central axis A of the piston 100 is the longitudinal section of the piston 100. The intersection line between the wall of the intake-side recess 111 and any longitudinal section that intersects with it is the first profile of the intake-side recess 111. The wall of the intake-side recess 111 is obtained by rotating this first profile around the central axis A of the piston 100. This first profile includes a maximum speed curve, the starting point of which is located at the edge of the intake-side recess 111, and the maximum speed curve extends from the edge of the intake-side recess 111 to the bottom of the intake-side recess 111.

[0031] like Figure 3 and Figure 4As shown, the conventional piston combustion chamber recess is a hemispherical recess, that is, the arc curve of the intersection line between the wall of the combustion chamber recess and the plane containing the central axis A of the piston. In this embodiment of the present invention, the profile of the intake side recess 111 of the combustion chamber recess 11 is set as a brachistochrone curve. The brachistochrone curve is the trajectory of point P on the circle when the circle rolls along a straight line, which is also the shortest path in a gravitational field that allows an object to slide frictionlessly from one point to another lower point.

[0032] The piston 100 provided in this embodiment of the present invention has an intersection line between the wall of the intake side recess 111 and the plane containing the central axis A of the piston 100, which includes a maximum speed curve. The maximum speed curve extends from the edge of the combustion chamber recess 11 to the bottom of the combustion chamber recess 11. This can shorten the time it takes for the airflow to reach the bottom of the combustion chamber along the wall of the combustion chamber recess 11 during the intake process, and increase the average speed of the airflow. This helps to reduce the surface temperature of the piston 100, and reduces the risk of cylinder head 200 cracks and knocking caused by high heat load. It also helps to increase the intensity of in-cylinder turbulence and reduce in-cylinder gas turbulence dissipation.

[0033] See Figure 4 The wall surface of the exhaust-side recess 112 is a smooth curved surface, which can be a hemispherical surface, similar in shape to the conventional combustion chamber recess 11. Alternatively, the intersection line between the wall surface of the exhaust-side recess 112 and the plane containing the central axis A of the piston 100 is a second profile line, which is the same as the first profile line. That is, the second profile line includes the fastest curve extending from the edge of the exhaust-side recess 112 to the bottom of the exhaust-side recess 112, and this fastest curve is the same as the fastest curve of the first profile line. In this way, the machining difficulty of the combustion chamber recess 11 can be reduced.

[0034] When the intersection of the wall of the intake-side recess 111 and the plane containing the central axis A of the piston 100 is a first profile, and the wall of the exhaust-side recess 112 is a hemispherical surface or its intersection with the plane containing the central axis A of the piston 100 is a second profile, the combustion chamber recess 11 has no obvious narrowing. Thus, on the one hand, see... Figure 5 This facilitates the removal of residual exhaust gases from the combustion chamber during valve overlap, preventing these gases from heating the cylinder gases and thus improving the cylinder charge coefficient; on the other hand, see... Figure 6 and Figure 7 This helps reduce turbulent dissipation in the combustion chamber during compression, allowing the intake vortex to be maintained for a longer period of time, which in turn helps increase the flame propagation speed after ignition and reduce cycle fluctuations.

[0035] See Figure 2 and Figure 3In this embodiment of the invention, the end of the fastest curve closest to the piston top surface 12 is taken as the starting point, and the tangent of the fastest curve at the starting point is parallel to the central axis A of the piston 100. That is, the tangent at the starting point of the fastest curve is perpendicular to the horizontal plane. This ensures that the resistance of the gas moving along the wall of the combustion chamber recess 11 through the intake valve 21 during the intake process is minimized. This allows the airflow to reach the bottom of the combustion chamber recess 11 in the shortest time, and the average airflow speed reaches the maximum.

[0036] The piston 100 provided in this embodiment of the present invention also includes an arc transition surface 13. The intake-side recess 111 and the exhaust-side recess 112 are both connected to the piston top surface 12 through the arc transition surface 13. The intersection of the arc transition surface 13 and the plane containing the central axis A of the piston 100 is an arc line, and the arc line is tangent to the speed curve at the starting point of the speed curve.

[0037] Understandably, the arc transition surface 13 surrounds the combustion chamber recess 11 and is located between the combustion chamber recess 11 and the piston top surface 12. Specifically, the arc transition surface 13 located between the intake-side recess 111 and the piston top surface 12 connects the intake-side recess 111 and the piston top surface 12, and the arc transition surface 13 located between the exhaust-side recess 112 and the piston top surface 12 connects the exhaust-side recess 112 and the piston top surface 12. This prevents the airflow from separating between the piston top surface 12 and the combustion chamber recess 11.

[0038] Specifically, the intersection of the piston top surface 12 and the plane containing the central axis A of the piston 100 is the third profile line. The intersection of the arc transition surface 13 and the plane containing the central axis A of the piston 100 is the fourth profile line, which is an arc line. The two ends of the fourth profile line of the arc transition surface 13 located between the intake-side recess 111 and the piston top surface 12 are respectively connected to the first profile line and the third profile line, and are tangent to the first profile line. The two ends of the fourth profile line of the arc transition surface 13 located between the exhaust-side recess 112 and the piston top surface 12 are respectively connected to the second profile line and the third profile line, and are tangent to the second profile line.

[0039] Furthermore, the piston top surface 12 is perpendicular to the central axis A of the piston 100, and the distance between the starting point of the fastest curve and the piston top surface 12 in the axial direction of the piston 100 is equal to the radius of the arc.

[0040] See Figure 2The third profile of the piston top surface 12 is perpendicular to the central axis A of the piston 100, and the tangent at the starting point of the fastest curve is parallel to the central axis A. The fourth profile is an arc with a radius of r. The distance between the edge of the combustion chamber recess 11 and the piston top surface 12 along the axial direction of the piston 100, i.e., the distance between the starting point of the fastest curve and the third profile along the axial direction of the piston 100, is h3, where h3 = r. This means that the starting point of the fastest curve and the third profile are connected by a quarter-circle arc, and the two ends of this arc are tangent to the fastest curve and the third profile, respectively. Thus, the arc transition surface 13 is tangent to both the combustion chamber recess 11 and the piston top surface 12, forming a smoother transition from the combustion chamber recess 11 to the piston top surface 12. Typically, the radius R1 of the arc satisfying this condition ranges from (1 to 7) mm.

[0041] Specifically, the fastest curves of the first and second profiles are both connected to the third profile through an arc of radius r.

[0042] In this embodiment of the invention, the tangent at the starting point of the fastest curve is parallel to the central axis A of the piston 100. The end of the fastest curve furthest from the piston top surface 12 is the endpoint, and the tangent at the endpoint of the fastest curve is perpendicular to the central axis A of the piston 100. That is, the fastest curve in this embodiment of the invention is a complete semi-circular cycloid. Figure 3 The image shows the trajectory of point P as the pendulum circle of radius R completes half a revolution. The coordinates (x, y) of this brachistochrone curve satisfy the following equation: x = R × (θ / 180×π - sinθ) y = R × (1 - cosθ) Where R is the radius of the pendulum circle of the fastest curve, and θ is the angle of the pendulum circle's roll (0°≤θ≤180°).

[0043] Further, see Figure 3 The radius of the pendulum circle of the fastest speed curve is R, and the distance between the starting point of the fastest speed curve and the central axis A of piston 100 is πR. Thus, the ending point of the fastest speed curve coincides with the central axis A of piston 100. Correspondingly, the axial distance between the starting and ending points of the fastest speed curve on piston 100 is h2, where h2 is equal to the diameter of the pendulum circle, 2R. The distance between the piston top surface 12 and the ending point of the fastest speed curve is h1 = 2R + r.

[0044] Understandably, the first profile is essentially a complete semi-arched cycloid. This minimizes the time it takes for the airflow to reach the bottom of the combustion chamber recess 11 along its walls, thereby maximizing the average airflow velocity, increasing in-cylinder turbulence intensity, and minimizing in-cylinder gas turbulence dissipation. Similarly, the second profile is also a complete semi-arched cycloid, meaning the entire combustion chamber recess 11 is obtained by rotating the complete semi-arched cycloid around the central axis A of the piston 100.

[0045] In a specific embodiment of this utility model, see Figure 2 Both the first and second profiles are speed curves, and the speed curves are complete semi-circular cycloids. That is, the distance between the starting point of the speed curve and the central axis A of the piston 100 is πR, and the diameter D3 of the combustion chamber recess 11 is 2πR. The distance h2 between the starting point and the ending point of the speed curve on the axial direction of the piston 100 is 2R. The distance h3 between the starting point of the speed curve and the third profile on the axial direction of the piston 100 is equal to the radius r of the fourth profile of the arc transition surface 13. Correspondingly, the maximum opening diameter D2 of the top of the piston 100 is 2πR + 2r.

[0046] Based on the above embodiments, the radius of the swing circle of the fastest curve is 0.07 to 0.15 times the diameter of piston 100. See also Figure 2 The piston 100 has a diameter of D1, and the radius of the pendulum circle of the fastest curve is R = (0.07~0.15)D1.

[0047] In this embodiment of the invention, the piston top surface 12 is provided with clearance recesses corresponding to the positions of the intake valve 21 and the exhaust valve 22. This avoids collision between the piston 100 and the valves when the piston reaches top dead center, and also helps to form vortices to improve fuel-air mixing and accelerate the combustion process.

[0048] See Figures 5-7 This utility model embodiment also provides a gas internal combustion engine, which includes a cylinder head 200, a cylinder liner 300, and a piston 100 as described in any of the above embodiments. The piston 100 is movably disposed within the cylinder liner 300, and the cylinder head 200 is connected to one end of the cylinder liner 300. The cylinder liner 300, piston 100, and cylinder head 200 together form a combustion chamber. The cylinder head 200 is provided with an intake valve 21 and an exhaust valve 22.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A piston, characterized in that, include: The combustion chamber recess includes an intake-side recess and an exhaust-side recess. The intersection of the wall of the intake-side recess and the plane containing the central axis of the piston is a first profile. The first profile includes a maximum speed curve, which extends from the edge of the intake-side recess to the bottom of the intake-side recess. The wall of the exhaust-side recess is a smooth curved surface. The piston top surface surrounds the combustion chamber recess and is connected to the intake side recess and the exhaust side recess; The piston is adapted to be installed inside the cylinder liner, one end of the cylinder liner is connected to the cylinder head, the cylinder liner, the piston and the cylinder head surround to form a combustion chamber, the cylinder head is provided with an intake valve and an exhaust valve, the intake side recess corresponds to the intake valve and the exhaust side recess corresponds to the exhaust valve.

2. The piston according to claim 1, characterized in that, The intersection of the wall of the exhaust-side recess and the plane containing the central axis is the second profile line, which is the same as the first profile line.

3. The piston according to claim 2, characterized in that, The fastest curve starts at the end closest to the top surface of the piston, and the tangent of the fastest curve at the starting point is parallel to the central axis.

4. The piston according to claim 3, characterized in that, Also includes: The circular arc transition surface connects the intake-side recess and the exhaust-side recess to the piston top surface. The intersection of the circular arc transition surface and the plane containing the central axis is an arc line, which is tangent to the fastest curve at the starting point.

5. The piston according to claim 4, characterized in that, The top surface of the piston is perpendicular to the central axis, and the distance between the starting point and the top surface of the piston along the axial direction of the piston is equal to the radius of the arc.

6. The piston according to claim 3, characterized in that, The end of the fastest curve furthest from the top surface of the piston is the endpoint, and the tangent of the fastest curve at the endpoint is perpendicular to the central axis.

7. The piston according to claim 6, characterized in that, The radius of the pendulum of the fastest curve is R, and the distance between the starting point of the fastest curve and the central axis of the piston is πR.

8. The piston according to claim 1, characterized in that, The radius of the swing circle of the fastest curve is 0.07 to 0.15 times the piston diameter.

9. The piston according to claim 1, characterized in that, The piston top surface is provided with clearance recesses corresponding to the positions of the intake valve and exhaust valve.

10. A gas-fired internal combustion engine, characterized in that, include: The cylinder head, cylinder liner, and piston as described in any one of claims 1-9, wherein the piston is movably disposed within the cylinder liner, the cylinder head is connected to one end of the cylinder liner, and the cylinder liner, the piston, and the cylinder head surround to form a combustion chamber.

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