Combustion chamber, engine

Abstract

This application relates to a combustion chamber and an engine. The combustion chamber includes a recess located on the top of a piston, the recess comprising: a bottom rotating groove, the center of rotation of which is collinear with the piston axis, the central cross-section of which is semi-elliptical, the major axis of which is along the radial direction of the piston; and a top rotating groove communicating with the bottom rotating groove, the center of rotation of which is collinear with the piston axis, the top rotating groove forming an opening on the top of the piston. This application can generate stronger tumble flow than conventional pistons, increasing in-cylinder turbulent kinetic energy, thereby accelerating combustion speed and improving thermal efficiency.

Description

Technical Field

[0001] This application relates to the field of engine technology, and in particular to a combustion chamber and an engine. Background Technology

[0002] Gas engines employ premixed combustion and spark plug ignition. The combustion speed is related to turbulent kinetic energy, and increasing turbulent kinetic energy can improve thermal efficiency. Traditional gas engines, based on diesel engine modifications, use vortex intake ports to generate turbulent kinetic energy by increasing the piston's extrusion area and utilizing the impact of extrusion flow and vortex. However, the effect is limited and the thermal efficiency is not high.

[0003] With the increasing market share of natural gas engines, utilizing tumble intake to enhance turbulent kinetic energy has become a trend, making improving tumble in gas engines an important research direction. However, existing combustion chamber designs for improving tumble suffer from several drawbacks, such as shape limitations preventing full utilization of intake flow, high processing difficulty, high manufacturing costs, difficulty in integrating cooling oil passages, large piston temperature gradients affecting reliability, limited effectiveness of tumble enhancement through squeeze flow, and low tumble performance at low speeds. Summary of the Invention

[0004] Based on this, a combustion chamber and an engine are provided to improve the tumble flow of a gas engine.

[0005] This application provides a combustion chamber for use in an engine, the engine including a cylinder and a piston. The combustion chamber includes a recess located on the top of the piston, the recess including: a bottom rotary groove, the center of rotation of the bottom rotary groove being collinear with the axis of the piston, the central cross-section of the bottom rotary groove being semi-elliptical, the major axis of the semi-ellipse being along the radial direction of the piston; and a top rotary groove communicating with the bottom rotary groove, the center of rotation of the top rotary groove being collinear with the axis of the piston, the top rotary groove forming an opening on the top of the piston.

[0006] According to one embodiment of this application, it further includes: a pair of guide grooves symmetrically arranged about the axis of the piston and disposed on both sides of the top rotary groove along the radial direction of the piston, the guide grooves communicating with the top rotary groove on one side along the radial direction of the piston, the guide grooves extending to the side wall of the piston on the other side along the radial direction of the piston, and the guide grooves extending to the top surface of the piston on one side along the axial direction of the piston.

[0007] According to one embodiment of this application, the engine includes a first intake valve, a second intake valve, a first exhaust valve, and a second exhaust valve. The orthographic projection of the first intake valve onto the top surface of the piston and the orthographic projection of the second intake valve onto the top surface of the piston are symmetrical about a first plane, and the orthographic projection of the first exhaust valve onto the top surface of the piston and the orthographic projection of the second exhaust valve onto the top surface of the piston are symmetrical about the first plane. The first plane passes through the rotation center of the bottom rotary groove and the top rotary groove. A pair of guide grooves are symmetrically arranged about the first plane.

[0008] According to one embodiment of this application, the guide groove extends circumferentially along the piston, and both ends of the guide groove in the extension direction have guide radii connecting the bottom of the guide groove and the top surface of the piston, respectively, and the guide radii at both ends of the guide groove are symmetrical about a second plane; wherein, the guide radii gradually incline from one end near the outer wall of the piston to one end away from the outer wall of the piston towards the side away from the second plane; wherein, the second plane passes through the axis of the piston and is perpendicular to the first plane.

[0009] According to one embodiment of this application, the ratio of the length L1 of the orthographic projection of the guide groove in the first plane direction to the diameter D of the cylinder is greater than or equal to 0.5 and less than or equal to 0.9; the ratio of the distance h2 from the bottom of the guide groove to the top surface of the piston to the distance h1 from the junction of the top rotary groove and the bottom rotary groove to the top surface of the piston is greater than 0 and less than or equal to 1.5; the ratio of the diameter r1 of the guide fillet to the distance h2 from the bottom of the guide groove to the top surface of the piston is greater than 0 and less than or equal to 1.

[0010] According to one embodiment of this application, the sidewall of the top rotating groove is tangent to the sidewall of the bottom rotating groove; and / or, the angle between the two sides of the cross-section of the top rotating groove on the first plane and the major axis of the cross-section of the bottom rotating groove on the first plane is greater than or equal to 90° and less than or equal to 120°.

[0011] According to one embodiment of this application, the difference between the diameter D of the cylinder and the major axis d1 of the semi-ellipse is greater than or equal to 8 mm and less than or equal to 20 mm; the ratio of the minor axis d2 of the semi-ellipse to the diameter D of the cylinder is greater than or equal to 0.1 and less than or equal to 0.3.

[0012] According to one embodiment of this application, the distance h1 from the position where the top rotary groove and the bottom rotary groove meet to the top surface of the piston is less than or equal to 20 mm.

[0013] This application also provides an engine, including a cylinder, a piston, and a combustion chamber according to the above embodiments, wherein the combustion chamber is located between the cylinder and the piston.

[0014] According to one embodiment of this application, when the combustion chamber includes a pair of guide grooves, the portion of the peripheral wall of the top rotary groove located between the pair of guide grooves constitutes a pair of forward airflow guides; the pair of forward airflow guides are symmetrically arranged about the plane passing through the piston axis.

[0015] The aforementioned combustion chamber and engine, with its concave structure design, allow the air-fuel mixture to flow in an orderly manner according to the shape of the concave and the piston's motion. The central cross-section of the bottom rotary groove is semi-elliptical, with its major axis along the piston's radial direction. This helps guide the airflow to generate a certain movement tendency in the piston's radial direction, which, combined with the piston's motion, lays the foundation for tumble formation. Furthermore, the bottom and top rotary grooves are collinear with the piston axis, ensuring relatively uniform airflow force during piston movement. This creates conditions for stable airflow and energy conversion within the combustion chamber. Therefore, this application can generate stronger tumble than traditional pistons, increasing in-cylinder turbulent kinetic energy, thereby accelerating combustion speed and improving thermal efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the piston structure provided in one embodiment of this application.

[0017] Figure 2 A cross-sectional view of a piston provided in one embodiment of this application.

[0018] Figure 3 A diagram showing the correspondence between the combustion chamber and the first intake valve, the second intake valve, the first exhaust valve, and the second exhaust valve, provided in an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of a combustion chamber showing a bottom rotating groove, provided in an embodiment of this application.

[0020] Figure 5 This is a schematic diagram of the structure of the guide groove in the combustion chamber provided in an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of the airflow guiding function of the guide groove in the combustion chamber provided in an embodiment of this application.

[0022] Figure 7 This is a comparison chart of the in-cylinder tumble ratio between a conventional combustion chamber and the combustion chamber of this embodiment.

[0023] Figure 8 This is a comparison diagram of the in-cylinder turbulent kinetic energy between a conventional combustion chamber and the combustion chamber of this embodiment.

[0024] Figure 9 This is a comparison diagram of the in-cylinder velocity field of a conventional combustion chamber and the combustion chamber of this embodiment during the intake process.

[0025] Figure 10 This is a comparison diagram of the in-cylinder velocity field of a conventional combustion chamber and the combustion chamber of this embodiment during the compression stroke.

[0026] Figure label:

[0027] 10. Piston;

[0028] 20. Recess; 21. Bottom rotary groove; 22. Top rotary groove; 23. Guide groove; 24. Guide rounded corner; 25. Forward airflow guide section;

[0029] 30. First intake valve; 31. Second intake valve; 32. First exhaust valve; 33. Second exhaust valve;

[0030] M1, the first plane; M2, the second plane. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0037] Combination Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the piston structure provided in one embodiment of this application. Figure 2 A cross-sectional view of a piston provided in one embodiment of this application.

[0038] The combustion chamber of this embodiment is applied to an engine, which includes a cylinder and a piston 10. The cylinder provides space for the reciprocating motion of the piston 10 and is also the site of combustion of the air-fuel mixture. The piston 10 is located inside the cylinder, forming a sealed space with the cylinder wall, and reciprocates up and down during engine operation. The combustion chamber is located in the area between the top of the piston 10 and the cylinder head, and is part of the internal space of the cylinder. It is a key component for generating energy through the combustion of the air-fuel mixture.

[0039] The combustion chamber of this embodiment includes a recess 20 located on the top of the piston 10. The recess 20 includes a bottom rotating groove 21 and a top rotating groove 22. The rotation center of the bottom rotating groove 21 is collinear with the axis of the piston 10, and the central cross-section of the bottom rotating groove 21 is semi-elliptical, with the major axis of the semi-ellipse along the radial direction of the piston 10. The top rotating groove 22 communicates with the bottom rotating groove 21, and the rotation center of the top rotating groove 22 is collinear with the axis of the piston 10. The top rotating groove 22 forms an opening on the top of the piston 10.

[0040] The major axis of the semi-ellipse is along the radial direction of the piston 10, and the minor axis of the semi-ellipse is parallel to the axial direction of the piston 10. The width gradually decreases from the side near the top of the piston 10 to the side away from the top of the piston 10.

[0041] The upper end of the top rotating groove 22 extends to the top of the piston 10 to form an opening at the top of the piston 10, and the lower end of the top rotating groove 22 connects to the upper end of the bottom rotating groove 21, thereby forming a continuous pit 20 structure on the upper side of the piston 10.

[0042] This embodiment, through the aforementioned structure, allows the air-fuel mixture to flow in an orderly manner after entering the combustion chamber, based on the shape of the recess 20 and the movement pattern of the piston 10. The semi-elliptical major axis of the bottom rotating groove 21, along the radial direction of the piston 10, helps guide the airflow to generate a certain movement trend in the radial direction, which, combined with the movement of the piston 10, lays the foundation for the formation of tumble flow. Furthermore, the collinearity of the centerlines of the top rotating groove 22 and the bottom rotating groove 21 with the piston 10 axis ensures that the airflow experiences relatively uniform force during the piston 10's movement, creating conditions for stable airflow and energy conversion within the combustion chamber, thereby contributing to improved combustion efficiency.

[0043] In addition, combining the top rotating groove 22 with the bottom rotating groove 21 helps to reduce the loss of gas kinetic energy. Specifically, after the airflow enters the pit 20 and flows along the pit 20 to the other side, under the guiding and projecting action of the corresponding side of the bottom rotating groove 21 and the corresponding side of the top rotating groove 22, the airflow can turn more smoothly, avoiding the airflow from vertically impacting the side wall of the pit 20 and causing a large loss of kinetic energy, and also preventing some airflow from turning downwards and affecting the formation of tumble.

[0044] Furthermore, during the intake cycle, when the mixture of fuel gas and air enters the cylinder through the intake manifold, the tangential intake manifold typically results in a higher intake air velocity towards the exhaust valve. This high-velocity intake air moves from the intake valve to the exhaust valve and then along the cylinder wall to the piston 10. Gas located at the center of the cylinder first enters the recess 20. The top rotary groove 22, located above the bottom rotary groove 21, reduces the kinetic energy loss caused by the gas turning into the recess 20.

[0045] Combination Figure 1 In some embodiments of this application, the combustion chamber further includes a pair of guide grooves 23. The pair of guide grooves 23 are symmetrically arranged about the axis of the piston 10 and are placed on both sides of the top rotary groove 22 along the radial direction of the piston 10. One side of the guide groove 23 along the radial direction of the piston 10 communicates with the top rotary groove 22, the other side of the guide groove 23 along the radial direction of the piston 10 extends to the side wall of the piston 10, and the other side of the guide groove 23 along the axial direction of the piston 10 extends to the top surface of the piston 10.

[0046] The guide groove 23 forms symmetrical notches on both sides of the top rotating groove 22. These notches serve as lateral airflow guiding areas. After the air-fuel mixture enters the combustion chamber, the guide groove 23 can guide the airflow from the top rotating groove 22 to a wider area, including the vicinity of the piston 10 sidewall. During the movement of the piston 10, this guiding effect can generate motion components in the airflow at different positions and directions, enhancing the uniformity of airflow distribution within the combustion chamber. The symmetrical arrangement ensures the balance of airflow on both sides, avoiding local airflow turbulence caused by asymmetry, further stabilizing the airflow state within the combustion chamber, and providing a guarantee for the formation of regular and high-intensity tumble flow, thereby improving combustion efficiency.

[0047] Figure 3 This diagram illustrates the correspondence between the combustion chamber and the first intake valve, second intake valve, first exhaust valve, and second exhaust valve according to an embodiment of this application. Figure 3 The dashed lines in the figure represent the orthographic projection positions of the first intake valve, the second intake valve, the first exhaust valve, and the second exhaust valve on the top surface of the piston 10.

[0048] Combination Figure 3 In some embodiments, the engine includes a first intake valve 30, a second intake valve 31, a first exhaust valve 32, and a second exhaust valve 33. The orthographic projection of the first intake valve 30 onto the top surface of the piston 10 and the orthographic projection of the second intake valve 31 onto the top surface of the piston 10 are symmetrical about a first plane M1, and the orthographic projection of the first exhaust valve 32 onto the top surface of the piston 10 and the orthographic projection of the second exhaust valve 33 onto the top surface of the piston 10 are symmetrical about the first plane M1. The first plane M1 passes through the rotation center of the bottom rotary groove 21 and the top rotary groove 22. A pair of guide grooves 23 are symmetrically arranged about the first plane M1.

[0049] The symmetrical relationship between the engine valves and the guide grooves 23 ensures the coordination of the intake and exhaust processes. Specifically, the projections of the first intake valve 30, the second intake valve 31, the first exhaust valve 32, and the second exhaust valve 33 onto the top surface of the piston 10 are symmetrical about the first plane M1. Similarly, the pair of guide grooves 23 are also symmetrical about the first plane M1. During intake, the symmetrical valve layout ensures that the air-fuel mixture entering the combustion chamber is relatively evenly distributed on both sides in terms of quantity and velocity. The symmetrical structure of the pair of guide grooves 23 can correspondingly and evenly guide the intake airflow to different areas within the combustion chamber, ensuring uniform initial conditions for tumble formation. During exhaust, the same symmetrical relationship facilitates the even discharge of exhaust gas, preventing residual exhaust gas from affecting the next round of intake and combustion due to localized poor exhaust flow. This symmetrical relationship improves the stability and repeatability of the entire combustion cycle, contributing to increased combustion efficiency and reduced emissions.

[0050] Combination Figure 1 , Figure 3 and Figure 6 In some embodiments, the guide groove 23 extends circumferentially along the piston 10, and the two ends of the guide groove 23 extending in the direction of extension have guide fillets 24 connecting the bottom of the guide groove 23 and the top surface of the piston 10, respectively. The guide fillets 24 at both ends of the guide groove 23 are symmetrical about the second plane M2. The guide fillets 24 gradually incline from the end near the outer wall of the piston 10 to the end away from the outer wall of the piston 10, moving away from the second plane M2. The second plane M2 passes through the axis of the piston 10 and is perpendicular to the first plane M1.

[0051] In this embodiment, the guide groove 23 extends circumferentially along the piston 10 and has guide fillets 24 at both ends. The special inclined design of the guide fillets 24 has a significant impact on the airflow direction and energy loss. When the airflow moves circumferentially along the guide groove 23 to both ends, the guide fillets 24 can smoothly change the direction of the airflow, avoiding energy loss caused by sudden turning, and allowing the airflow to maintain high kinetic energy to continue moving in the combustion chamber. At the same time, the characteristic of the fillet gradually tilting from the end near the outer wall of the piston 10 to the end away from the outer wall and away from the second plane M2 plays a corrective role for the circumferential airflow. Under the combined action of the piston 10 movement and the intake airflow, the circumferential airflow is prone to generate vortices, but the guide fillets 24 can adjust the circumferential velocity component of the airflow, reduce the formation of vortices, convert more airflow energy into tumble flow that is conducive to combustion, improve the quality and intensity of the tumble flow, and promote more complete combustion of the air-fuel mixture.

[0052] In some embodiments, the ratio of the length L1 of the orthographic projection of the guide groove 23 in the direction of the first plane M1 to the diameter D of the cylinder is greater than or equal to 0.5 and less than or equal to 0.9. Preferably, the ratio of the length L1 of the orthographic projection of the guide groove 23 in the direction of the first plane M1 to the diameter D of the cylinder is greater than or equal to 0.7 and less than or equal to 0.8, for example, the ratio of the length L1 of the orthographic projection of the guide groove 23 in the direction of the first plane M1 to the diameter D of the cylinder is 0.75.

[0053] The ratio of the length L1 of the orthographic projection of the guide groove 23 in the first plane M1 direction to the cylinder diameter D affects its guiding range of airflow. When the ratio of the length L1 of the orthographic projection of the guide groove 23 in the first plane M1 direction to the cylinder diameter D is within the above-mentioned range, it can ensure that the airflow at different radial positions of the cylinder can be effectively guided, avoiding local airflow loss due to excessive or insufficient length.

[0054] Optionally, the ratio of the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 and the distance h1 from the junction of the top and bottom rotating grooves 22 to the top surface of the piston 10 is greater than 0 and less than or equal to 1.5. Preferably, the ratio of the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 and the distance h1 from the junction of the top and bottom rotating grooves 22 to the top surface of the piston 10 is greater than 0.5 and less than or equal to 1.2. For example, the ratio of the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 and the distance h1 from the junction of the top and bottom rotating grooves 22 to the top surface of the piston 10 is 1. The range of the ratio of the distance from the bottom of the guide groove 23 to the top surface of the piston 10 to the distance from the junction of the top and bottom rotating grooves 22 to the top surface of the piston 10 determines the flow space and velocity variation of the airflow in different height regions. Within the aforementioned range, an orderly velocity gradient can be formed between different height levels of the airflow, promoting vertical mixing and energy transfer, which helps to form a stable tumble structure.

[0055] Optionally, the ratio of the diameter r1 of the guide fillet 24 to the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 is greater than 0 and less than or equal to 1. Preferably, the ratio of the diameter r1 of the guide fillet 24 to the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 is greater than or equal to 0.4 and less than or equal to 0.6. For example, the ratio of the diameter r1 of the guide fillet 24 to the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 is 0.5.

[0056] The ratio range of the diameter r1 of the aforementioned guide fillet 24 to the width of the orthographic projection of the guide groove 23 in the direction of the first plane M1 further precisely controls the flow characteristics of the airflow in the local area, which can reduce the energy loss of the airflow during the turning and flow process, optimize the overall distribution of the airflow in the combustion chamber, improve the stability and intensity of the tumble flow, and thus improve the combustion efficiency.

[0057] In some embodiments, the sidewall of the top rotating groove 22 is tangent to the sidewall of the bottom rotating groove 21. This tangential relationship between the top and bottom rotating grooves 22 and 21 allows for a smoother transition of airflow between them. When airflow enters the top rotating groove 22 from the bottom rotating groove 21, the tangential design avoids airflow disturbances and energy loss caused by sudden structural changes, ensuring the continuity and stability of the airflow.

[0058] Optionally, the angle between the two sides of the cross-section of the top rotating groove 22 on the first plane M1 and the major axis of the cross-section of the bottom rotating groove 21 on the first plane M1 is greater than or equal to 90° and less than or equal to 120°, that is, the angle α between the extension lines of the two sides of the cross-section of the top rotating groove 22 on the first plane M1 and the major axis of the cross-section of the bottom rotating groove 21 on the first plane M1 is greater than or equal to 60° and less than or equal to 90°.

[0059] The angle range between the two sides of the top rotating groove 22 on the cross-section of the first plane M1 and the long axis of the bottom rotating groove 21 on the cross-section of the first plane M1 affects the flow path and velocity variation of the air-fuel mixture between these two regions. This angle range between the two sides of the top rotating groove 22 on the cross-section of the first plane M1 and the long axis of the bottom rotating groove 21 on the cross-section of the first plane M1 can guide the airflow to flow at appropriate angles and velocities between different regions, adjusting the direction and energy distribution of the airflow, making it more conducive to the formation and development of tumble. This structural relationship optimizes the flow process of the air-fuel mixture in the combustion chamber, improves the tumble effect, promotes complete combustion of the air-fuel mixture, and thus improves combustion efficiency.

[0060] Combination Figure 2 , Figure 4 and Figure 5In some embodiments, the difference between the cylinder diameter D and the major axis d1 of the semi-ellipse is greater than or equal to 8 mm and less than or equal to 20 mm. Preferably, the difference between the cylinder diameter D and the major axis d1 of the semi-ellipse is greater than or equal to 12 mm and less than or equal to 16 mm. For example, the difference between the cylinder diameter D and the major axis d1 of the semi-ellipse is 14 mm or 15 mm. This difference in cylinder diameter D and the major axis d1 of the semi-ellipse allows for a more rational spatial arrangement of the bottom rotating groove 21 within the cylinder, enabling it to adapt to the flow rate and velocity requirements of the air-fuel mixture under different operating conditions. During the intake process, the groove shape determined by the difference in the major axis can guide the airflow to form a specific flow pattern, which is beneficial for the generation of initial tumble flow.

[0061] Optionally, the ratio of the semi-elliptical minor axis d2 to the cylinder diameter D is greater than or equal to 0.1 and less than or equal to 0.3; for example, the ratio of the semi-elliptical minor axis d2 to the cylinder diameter D is 0.2. The ratio of the semi-elliptical minor axis to the cylinder diameter affects the depth and curvature of the groove. This ratio allows the airflow to generate suitable centrifugal force and pressure changes within the groove, further promoting the development of tumble flow, increasing the initial intensity of tumble flow, and providing a foundation for forming a stable and high-intensity tumble flow throughout the combustion chamber, thereby improving combustion efficiency.

[0062] In some embodiments, the distance h1 from the junction of the top rotating groove 22 and the bottom rotating groove 21 to the top surface of the piston 10 is less than or equal to 20 mm. Preferably, the distance h1 from the junction of the top rotating groove 22 and the bottom rotating groove 21 to the top surface of the piston 10 is greater than or equal to 8 mm and less than or equal to 15 mm. For example, the distance h1 from the junction of the top rotating groove 22 and the bottom rotating groove 21 to the top surface of the piston 10 is 8 mm, 10 mm, 12 mm, or 14 mm, etc.

[0063] The distance between the junction of the top and bottom rotating grooves 22 and the top surface of the piston 10 affects the initial state of the air-fuel mixture entering the combustion chamber recess 20. Controlling the distance h1 between the junction of the top and bottom rotating grooves 22 and the top surface of the piston 10 within the aforementioned range ensures that the air-fuel mixture has appropriate velocity and pressure upon entering the recess 20, avoiding significant energy loss due to impact or restriction preventing the formation of tumble flow. This promotes uniform distribution of the air-fuel mixture within the combustion chamber and, in conjunction with the piston 10's movement and other structures, facilitates the formation and development of tumble flow, improving combustion efficiency. It also considers the rationality of the piston 10's structure and the optimization of its overall performance.

[0064] The conventional combustion chamber design and the combustion chamber design of this invention are compared through three-dimensional simulation calculations.

[0065] Figure 7This diagram compares the in-cylinder swirl ratio of a conventional combustion chamber and the combustion chamber of this embodiment. The solid line represents the conventional combustion chamber, and the dashed line represents the combustion chamber of this application. The intake stroke is from 0°CA to 180°CA, the compression stroke is from 180°CA to 360°CA, and the ignition timing is between 330°CA and 360°CA. The comparison shows that during the intake stroke, the swirl ratio of the combustion chamber of this embodiment is significantly higher than that of the conventional combustion chamber.

[0066] Figure 9 This diagram compares the in-cylinder velocity field of a conventional combustion chamber and the combustion chamber of this embodiment during the intake stroke. The left side represents the conventional combustion chamber, and the right side represents the combustion chamber of this embodiment. It can be seen that in the combustion chamber of this embodiment, during the intake stroke, the airflow enters the combustion chamber from the intake valve side (first intake valve 30 and second intake valve 31) (top left side of the diagram). Most of the gas moves towards the exhaust valve side (first exhaust valve 32 and second exhaust valve 33) (top right side of the diagram), then flows down the wall, exits through the recess 20, and rises again along the wall to reach the vicinity of the intake valves (first intake valve 30 and second intake valve 31), ultimately forming a tumble flow. In contrast, in the conventional combustion chamber, during the intake stroke, the airflow enters the combustion chamber from the intake valve (top left side of the diagram), and most of the gas moves towards the exhaust valve side (top right side of the diagram), but no tumble flow is formed.

[0067] During the compression stroke, it can be seen that the tumble ratio of the combustion chamber of this invention has a significant increase, such as... Figure 6 As shown.

[0068] Figure 10 This is a comparison diagram of the in-cylinder velocity field of a conventional combustion chamber and the combustion chamber of this embodiment during the compression stroke. It can be seen that the tumble flow in the combustion chamber of this embodiment is very regular, while the in-cylinder flow in a conventional combustion chamber is more chaotic.

[0069] Figure 8 This is a comparison diagram of the in-cylinder turbulent kinetic energy between a conventional combustion chamber and the combustion chamber of this embodiment. Figure 8 It can be seen that the turbulent kinetic energy of the combustion chamber in this embodiment near the ignition moment is about twice that of the conventional combustion chamber, which indicates that the tumble flow in the combustion chamber of this embodiment can be broken into smaller-scale turbulence near the ignition moment.

[0070] This invention also provides an engine, including a cylinder, a piston 10, and a combustion chamber of any of the above embodiments, the combustion chamber being located between the cylinder and the piston 10.

[0071] In this embodiment, the engine includes the combustion chamber structure described above, enabling optimized combustion performance. The structural design of the combustion chamber plays a crucial role in engine operation. During the intake stroke, the combustion chamber structure guides the air-fuel mixture to form a tumble flow conducive to combustion, improving the mixing degree and combustion speed. During the compression stroke, the shape and airflow guidance characteristics of the combustion chamber further enhance the tumble flow intensity, making the air-fuel mixture more uniform during compression and increasing the temperature and pressure of the mixture at the end of compression, creating favorable conditions for efficient combustion. During combustion and exhaust, the combustion chamber structure also ensures the stability of the combustion process and the smoothness of exhaust gas discharge, thereby reducing engine energy consumption, improving overall engine performance, and meeting the requirements for engine power and economy.

[0072] Furthermore, such as Figure 1 As shown, when the combustion chamber includes a pair of guide grooves 23, the portion of the peripheral wall of the top rotating groove 22 located between the pair of guide grooves 23 constitutes a pair of forward airflow guides 25, and the pair of forward airflow guides 25 are symmetrically arranged about the plane (i.e. the second plane M2 mentioned above) about the axis of the piston 10.

[0073] Therefore, during the intake process, the forward airflow guide 25 can more precisely guide the airflow entering from the intake valve in a specific direction, enhancing the directionality and controllability of the intake airflow within the combustion chamber. The symmetrical arrangement ensures the consistency and balance of the intake airflow on both sides during the guidance process, allowing the intake airflow to more effectively form a regular tumble within the combustion chamber. This precise airflow guidance improves combustion uniformity, enabling more complete combustion of the air-fuel mixture, thereby increasing combustion efficiency. Furthermore, it works in conjunction with other structures to optimize the engine's combustion process.

[0074] The working principle of the engine in this embodiment is as follows:

[0075] In the intake cycle, the mixture of fuel gas and air enters the cylinder through the intake passages of the first intake valve 30 and the second intake valve 31. Normally, the tangential intake passages result in a higher intake air velocity towards the first exhaust valve 32 and the second exhaust valve 33. This high-velocity intake air moves from the first intake valve 30 and the second intake valve 31 to the first exhaust valve 32 and the second exhaust valve 33, and then along the cylinder wall to the piston 10. Gas located at the center of the cylinder first enters the inner side of the forward airflow guide 25. The mating structure of the top rotating groove 22 and the bottom rotating groove 21 reduces the kinetic energy loss due to the gas turning during entry. The bottom rotating groove 21 guides the gas to the other end of the piston 10, where the forward airflow guide 25 on the other side of the piston 10 then propels the gas towards the first intake valve 30 and the second intake valve 31. This causes the airflow to turn 180°, causing the gas to flow towards the first intake valve 30 and the second intake valve 31, creating a tumble flow within the cylinder.

[0076] Gas located on both sides of the cylinder enters the guide groove 23. The guide fillets 24 at both ends of the guide groove 23 change the direction of airflow, reducing the kinetic energy loss caused by the change in airflow direction. At the same time, the guide fillets 24 also have a certain correction effect on the circumferential airflow, thereby reducing the in-cylinder turbulence and improving the in-cylinder tumble.

[0077] During compression, the piston 10 moves upward, further enhancing the guiding effect of the combustion chamber and increasing the tumble intensity. Before reaching top dead center, the high-intensity tumble breaks down into high-intensity turbulent kinetic energy. Ultimately, at ignition, this maximizes the turbulent kinetic energy within the cylinder, accelerating combustion and improving thermal efficiency.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A combustion chamber, characterized in that, Applied to an engine, the engine including a cylinder and a piston, the combustion chamber including a recess located on the top of the piston, the recess including: The bottom rotating groove has a rotation center that is collinear with the axis of the piston, and the central cross-section of the bottom rotating groove is semi-elliptical, with the major axis of the semi-ellipse along the radial direction of the piston. A top rotating groove communicates with the bottom rotating groove, the rotation center of the top rotating groove is collinear with the axis of the piston, and the top rotating groove forms an opening at the top of the piston; A pair of guide grooves are symmetrically arranged about the axis of the piston and are placed on both sides of the top rotary groove along the radial direction of the piston. One side of the guide groove along the radial direction of the piston is connected to the top rotary groove, the other side of the guide groove along the radial direction of the piston is extended to the side wall of the piston, and the other side of the guide groove along the axial direction of the piston is extended to the top surface of the piston. The engine includes a first intake valve, a second intake valve, a first exhaust valve, and a second exhaust valve. The orthographic projection of the first intake valve on the top surface of the piston and the orthographic projection of the second intake valve on the top surface of the piston are symmetrical about a first plane, and the orthographic projection of the first exhaust valve on the top surface of the piston and the orthographic projection of the second exhaust valve on the top surface of the piston are symmetrical about the first plane. Wherein, the first plane passes through the rotation center of the bottom rotary groove and the top rotary groove; The pair of guide slots are symmetrically arranged about the first plane; The guide groove extends circumferentially along the piston, and both ends of the guide groove in the extension direction have guide radii that connect the bottom of the guide groove and the top surface of the piston, respectively. The guide radii at both ends of the guide groove are symmetrical about the second plane. The guide fillet gradually slopes away from the second plane from one end near the piston outer wall to the end away from the piston outer wall. The second plane passes through the axis of the piston and is perpendicular to the first plane; The ratio of the length L1 of the orthographic projection of the guide groove in the first plane direction to the diameter D of the cylinder is greater than or equal to 0.5 and less than or equal to 0.

9. The ratio of the distance h2 from the bottom of the guide groove to the top surface of the piston and the distance h1 from the point where the top rotary groove and the bottom rotary groove meet to the top surface of the piston is greater than 0 and less than or equal to 1.

5. The ratio of the diameter r1 of the guide fillet to the distance h2 from the bottom of the guide groove to the top surface of the piston is greater than 0 and less than or equal to 1.

2. The combustion chamber according to claim 1, characterized in that, The sidewall of the top rotary groove is tangent to the sidewall of the bottom rotary groove; And / or, the angle between the two sides of the cross section of the top rotary groove on the first plane and the major axis of the cross section of the bottom rotary groove on the first plane is greater than or equal to 90° and less than or equal to 120°.

3. The combustion chamber according to claim 1 or 2, characterized in that, The difference between the diameter D of the cylinder and the major axis d1 of the semi-ellipse is greater than or equal to 8 mm and less than or equal to 20 mm. The ratio of the semi-elliptical minor axis d2 to the cylinder diameter D is greater than or equal to 0.1 and less than or equal to 0.

3.

4. The combustion chamber according to claim 1 or 2, characterized in that, The distance h1 from the point where the top rotary groove and the bottom rotary groove meet to the top surface of the piston is less than or equal to 20 mm.

5. An engine, characterized in that, It includes a cylinder, a piston, and a combustion chamber as described in any one of claims 1 to 4, the combustion chamber being located between the cylinder and the piston.

6. The engine according to claim 5, characterized in that, When the combustion chamber includes a pair of guide grooves, the portion of the peripheral wall of the top rotary groove located between the pair of guide grooves constitutes a pair of positive airflow guides; The pair of positive airflow guides are symmetrically arranged in a plane about the axis passing through the piston.

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