Combustion chamber and engine

Abstract

The invention relates to a combustion chamber and an engine. The combustion chamber comprises a pit located in the top of the piston, the pit comprises a bottom rotation groove, the rotation center of the bottom rotation groove is collinear with the axis of the piston, the center section of the bottom rotation groove is in a semi-oval shape, and the long axis of the semi-oval shape is in the radial direction of the piston; the top rotation groove is communicated with the bottom rotation groove, the rotation center of the top rotation groove is collinear with the axis of the piston, and the top rotation groove forms an opening in the top of the piston. The piston can generate stronger tumble compared with a traditional piston, turbulent kinetic energy in a cylinder is improved, and therefore the combustion speed is increased, and the heat efficiency is improved.

Description

Technical Field

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

[0002] Gas engines use premixed combustion and spark plug ignition. The combustion speed is related to turbulent kinetic energy. Improving turbulent kinetic energy can improve thermal efficiency. Traditional gas engines use vortex airways based on diesel engines. By increasing the piston squeezing area, squeezing flow and vortex impact generate turbulent kinetic energy, but the effect is limited and the thermal efficiency is not high.

[0003] As the market share of natural gas engines increases, using tumble intake to increase turbulent kinetic energy has become a trend, and how to improve tumble in gas engines has become an important research direction. At the same time, some existing combustion chamber solutions for improving tumble have problems such as limited shape that cannot fully utilize the intake flow, high processing difficulty, high manufacturing cost, difficulty in approaching the cooling oil channel, large piston temperature gradient affecting reliability, limited effect of increasing tumble by squeezing flow, and small tumble under low speed conditions. 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] The present application provides a combustion chamber, which is applied to an engine, wherein the engine comprises a cylinder and a piston, and the combustion chamber comprises a pit located at the top of the piston, wherein the pit comprises: a bottom revolving groove, wherein the center of rotation of the bottom revolving groove is colinear with the axis of the piston, the central cross-section of the bottom revolving groove is semi-elliptical, and the major axis of the semi-ellipse is along the radial direction of the piston; and a top revolving groove, which is connected to the bottom revolving groove, wherein the center of rotation of the top revolving groove is colinear with the axis of the piston, and the top revolving groove forms an opening at the top of the piston.

[0006] According to one embodiment of the present application, it also includes: a pair of guide grooves, which are symmetrically arranged about the axis of the piston and are disposed on both sides of the top rotary groove along the radial direction of the piston, the guide groove is connected to the top rotary groove along one radial side of the piston, the guide groove extends to the side wall of the piston along the other radial side of the piston, and the guide groove extends to the top surface of the piston along one axial side of the piston.

[0007] According to one embodiment of the present 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 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 rotation groove and the top rotation groove; wherein, a pair of the guide grooves are symmetrically arranged about the first plane.

[0008] According to one embodiment of the present application, the guide groove extends along the circumference of the piston, and the two ends of the guide groove in the extension direction respectively have guide fillets connecting the groove bottom of the guide groove and the top surface of the piston, and the guide fillets located at both ends of the guide groove are symmetrical about the second plane; wherein, the guide fillets gradually incline toward the side away from the second plane from one end close to the outer wall of the piston to the end away from the outer wall of the piston; wherein, the second plane passes through the axis of the piston and is perpendicular to the first plane.

[0009] According to one embodiment of the present 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 and the distance h1 from the connecting position of the top revolving groove and the bottom revolving 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 the present application, the side wall of the top revolving groove is tangent to the side wall of the bottom revolving groove; and / or, the angle between the two sides of the cross-section of the top revolving groove on the first plane and the long axis of the cross-section of the bottom revolving 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 the present 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 the present application, a distance h1 from a junction of the top revolving groove and the bottom revolving groove to a top surface of the piston is less than or equal to 20 mm.

[0013] The present application also provides an engine, comprising a cylinder, a piston and the combustion chamber of the above embodiment, wherein the combustion chamber is located between the cylinder and the piston.

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

[0015] The combustion chamber, engine, and combustion chamber pit structure design enable the mixture to flow in an orderly manner according to the pit shape and the law of piston movement after entering the combustion chamber. The central cross-section of the bottom rotary groove is semi-elliptical, and the major axis of the semi-ellipse is along the radial direction of the piston, which is conducive to guiding the airflow to produce a certain movement trend in the radial direction of the piston, and combined with the piston movement, it begins to lay the foundation for the formation of tumble flow. The bottom rotary groove and the top rotary groove are colinear with the piston axis to ensure that the airflow is relatively uniformly stressed during the piston movement, creating conditions for the subsequent stable flow and energy conversion of the airflow in the combustion chamber. Therefore, the present application can produce a stronger tumble flow than the traditional piston, increase the turbulent kinetic energy in the cylinder, thereby accelerating the combustion speed and improving the thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic structural diagram of a piston provided in one embodiment of the present application.

[0017] Figure 2 A cross-sectional view of a piston provided in accordance with an embodiment of the present application.

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

[0019] Figure 4 A schematic structural diagram showing a bottom rotary groove in a combustion chamber provided in one embodiment of the present application.

[0020] Figure 5 A schematic diagram of the structure of a guide groove in a combustion chamber provided in one embodiment of the present application.

[0021] Figure 6 A schematic diagram of the airflow guiding function of a guide groove in a combustion chamber provided in one embodiment of the present application.

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

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

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

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

[0026] Reference numerals:

[0027] 10. Piston;

[0028] 20. pit; 21. bottom rotation groove; 22. top rotation groove; 23. guide groove; 24. guide fillet; 25. positive airflow guide;

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

[0030] M1, first plane; M2, second plane. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0032] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0033] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0035] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0036] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, 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 implementation method.

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

[0038] The combustion chamber of the embodiment of the present application 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 place where the mixed gas burns. The piston 10 is located inside the cylinder, forming a sealed space with the cylinder wall, and reciprocates up and down during the operation of the engine. The combustion chamber is located in the area between the top of the piston 10 and the cylinder head, which is part of the internal space of the cylinder and is a key part for the combustion of the mixed gas to generate energy.

[0039] The combustion chamber of the embodiment of the present application includes a pit 20 located at the top of the piston 10, and the pit 20 includes a bottom revolving groove 21 and a top revolving groove 22. The center of rotation of the bottom revolving groove 21 is collinear with the axis of the piston 10, and the central cross-section of the bottom revolving groove 21 is semi-elliptical, and the major axis of the semi-ellipse is along the radial direction of the piston 10. The top revolving groove 22 is connected to the bottom revolving groove 21, and the center of rotation of the top revolving groove 22 is collinear with the axis of the piston 10, and the top revolving groove 22 forms an opening at 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 of the semi-ellipse gradually decreases from the side close to the top of the piston 10 to the side away from the top of the piston 10 .

[0041] The upper end of the top revolving 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 revolving groove 22 is connected to the upper end of the bottom revolving groove 21 , thereby forming a continuous pit 20 structure on the upper side of the piston 10 .

[0042] The above structure of this embodiment can make the mixed gas flow in an orderly manner according to the shape of the pit 20 and the movement law of the piston 10 after entering the combustion chamber. The semi-elliptical major axis of the bottom rotary groove 21 along the radial direction of the piston 10 is conducive to guiding the airflow to produce a certain movement trend in the radial direction, and combined with the movement of the piston 10, it begins to lay the foundation for the formation of tumble flow. The center lines of the top rotary groove 22 and the bottom rotary groove 21 are colinear with the axis of the piston 10 to ensure that the airflow is relatively uniformly stressed during the movement of the piston 10, creating conditions for the subsequent stable flow and energy conversion of the airflow in the combustion chamber, thereby helping to improve the combustion efficiency.

[0043] In addition, combining the top rotating groove 22 with the bottom rotating groove 21 is beneficial to reducing the loss of gas kinetic energy. Specifically, after the airflow enters the pit 20 and flows along the pit 20 to the other side, the airflow can be turned more smoothly under the guidance and ejection effect of the outer walls of the corresponding sides of the bottom rotating groove 21 and the corresponding sides of the top rotating groove 22, thereby avoiding the airflow from vertically colliding with the side walls of the pit 20 to cause a large kinetic energy loss, and avoiding the downward turning of part of the airflow to affect the formation of tumble flow.

[0044] In addition, in the intake cycle, when the mixture of fuel gas and air enters the cylinder through the intake duct, the tangential duct usually causes the intake air to flow faster toward the exhaust valve side, and the high-flow intake air moves from the intake valve to the exhaust valve side, and then reaches the piston 10 along the cylinder wall. The gas at the center of the cylinder first enters the pit 20, and the top revolving groove 22 is provided above the bottom revolving groove 21 to reduce the kinetic energy loss of the gas turning to enter the pit 20.

[0045] Combination Figure 1 In some embodiments of the present application, the combustion chamber also includes a pair of guide grooves 23, which are symmetrically arranged about the axis of the piston 10 and are disposed on both sides of the top revolving groove 22 along the radial direction of the piston 10. The guide groove 23 is connected to the top revolving groove 22 along one radial side of the piston 10, and the guide groove 23 extends to the side wall of the piston 10 along the other radial side of the piston 10, and the guide groove 23 extends to the top surface of the piston 10 along one axial side of the piston 10.

[0046] The guide groove 23 can form symmetrical notches on both sides of the top revolving groove 22. The notch position serves as a lateral airflow guiding area. After the mixed gas enters the combustion chamber, the guide groove 23 can guide the airflow from the top revolving groove 22 to a wider area, including the vicinity of the side wall of the piston 10. During the movement of the piston 10, this guiding effect can cause the airflow to generate motion components in different positions and directions, thereby enhancing the uniformity of the airflow distribution in the combustion chamber. The symmetrical setting ensures the balance of the airflow on both sides, avoids local airflow turbulence caused by asymmetry, further stabilizes the airflow state in the combustion chamber, and provides a guarantee for the formation of a regular and high-intensity tumble flow, thereby improving the combustion efficiency.

[0047] Figure 3 A corresponding relationship diagram of a combustion chamber and a first intake valve, a second intake valve, a first exhaust valve, and a second exhaust valve provided in an embodiment of the present application, Figure 3 The dotted lines in φ represent the positive 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 on the top surface of the piston 10 and the orthographic projection of the second intake valve 31 on the top surface of the piston 10 are symmetrical about a first plane M1, and the orthographic projection of the first exhaust valve 32 on the top surface of the piston 10 and the orthographic projection of the second exhaust valve 33 on the top surface of the piston 10 are symmetrical about the first plane M1; wherein the first plane M1 passes through the rotation center of the bottom rotation groove 21 and the top rotation groove 22; wherein a pair of guide grooves 23 are symmetrically arranged about the first plane M1.

[0049] The symmetrical relationship between the engine valve and the guide groove 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 on the top surface of the piston 10 are symmetrical about the first plane M1, and the pair of guide grooves 23 are also symmetrical about the first plane M1. During the intake process, the symmetrical valve layout makes the mixed gas entering the combustion chamber relatively evenly distributed on both sides in terms of quantity and speed. The symmetrical structure of the pair of guide grooves 23 can evenly guide the intake airflow to different areas in the combustion chamber, ensuring that the initial conditions for the formation of tumble flow are uniform. During the exhaust process, the same symmetrical relationship is conducive to the uniform discharge of exhaust gas, avoiding the residual exhaust gas caused by local exhaust stagnation affecting the next round of intake and combustion. This symmetrical relationship improves the stability and repeatability of the entire combustion cycle, which is conducive to improving combustion efficiency and reducing emissions.

[0050] Combination Figure 1 , Figure 3 and Figure 6 In some embodiments, the guide groove 23 extends along the circumference of the piston 10, and the two ends of the guide groove 23 in the extension direction respectively have guide fillets 24 connecting the groove bottom of the guide groove 23 and the top surface of the piston 10, and the guide fillets 24 located at both ends of the guide groove 23 are symmetrical about the second plane M2; wherein, the guide fillets 24 gradually incline toward the side away from the second plane M2 from one end close to the outer wall of the piston 10 to the end away from the outer wall of the piston 10; wherein, 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 along the circumference of the piston 10 and has guide fillets 24 at both ends. The special tilt design of the guide fillets 24 has an important influence on the direction of airflow movement and energy loss. When the airflow moves circumferentially along the guide groove 23 to both ends, the guide fillets 24 can make the airflow change direction smoothly, avoid the energy loss caused by sudden turning, and enable the airflow to maintain a high kinetic energy and continue to move in the combustion chamber. At the same time, the characteristic of the fillet gradually tilting from the end close to 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 in the circumferentially moving airflow. Under the combined action of the movement of the piston 10 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, and convert more airflow energy into tumbles that are beneficial to combustion, thereby improving the quality and intensity of the tumbles and promoting more complete combustion of the 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 range of the length L1 of the orthographic projection of the guide groove 23 in the direction of the first plane M1 to the cylinder diameter D affects the range of its guiding of the airflow. When 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 cylinder diameter D is within the above range, it can ensure that the airflow at different radial positions of the cylinder can be effectively guided, avoiding local airflow loss control caused by too long or too short a 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 rotary groove 22 and the bottom rotary groove 21 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 rotary groove 22 and the bottom rotary groove 21 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 rotary groove 22 and the bottom rotary groove 21 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 and the distance from the junction of the top rotary groove 22 and the bottom rotary groove 21 to the top surface of the piston 10 determines the flow space and velocity changes of the airflow in different height areas. Within the above range, the airflow can form an orderly velocity gradient between different height levels, promote the mixing and energy transfer of the airflow in the vertical direction, and help 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 above-mentioned guide fillet 24 to the width of the positive projection of the guide groove 23 in the direction of the first plane M1 further accurately controls the flow characteristics of the airflow in the local area, 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 strength of the tumble flow, and thus improve the combustion efficiency.

[0057] In some embodiments, the side wall of the top revolving groove 22 is tangent to the side wall of the bottom revolving groove 21. The tangent relationship between the top revolving groove 22 and the bottom revolving groove 21 makes the airflow transition between the two smoother. When the airflow enters the top revolving groove 22 from the bottom revolving groove 21, the tangent design avoids airflow disturbance and energy loss caused by sudden structural changes, and ensures the continuity and stability of the airflow.

[0058] Optionally, the angle between the two sides of the cross-section of the top revolving groove 22 on the first plane M1 and the long axis of the cross-section of the bottom revolving 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 revolving groove 22 on the first plane M1 and the long axis of the cross-section of the bottom revolving 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 cross section of the top revolving groove 22 on the first plane M1 and the long axis of the cross section of the bottom revolving groove 21 on the first plane M1 affects the flow path and speed change of the mixture between the two areas. The angle range between the two sides of the cross section of the top revolving groove 22 on the first plane M1 and the long axis of the cross section of the bottom revolving groove 21 on the first plane M1 can guide the airflow to flow at a suitable angle and speed between different areas, adjust the direction and energy distribution of the airflow, and make it more conducive to the formation and development of tumble flow. This structural relationship optimizes the flow process of the mixture in the combustion chamber, improves the tumble effect, promotes the full combustion of the mixture, and thus improves the combustion efficiency.

[0060] Combination Figure 2 , Figure 4 and Figure 5In some embodiments, 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. Preferably, the difference between the diameter D of the cylinder 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 diameter D of the cylinder and the major axis d1 of the semi-ellipse is 14 mm or 15 mm. The difference between the diameter D of the cylinder and the major axis d1 of the semi-ellipse makes the spatial layout of the bottom revolving groove 21 in the cylinder more reasonable, and can adapt to the flow and speed requirements of the mixed gas under different working conditions. During the intake process, the groove shape determined according to the major axis difference can guide the airflow to form a specific flow pattern, which is conducive to the generation of initial tumble flow.

[0061] Optionally, 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. For example, the ratio of the minor axis d2 of the semi-ellipse to the diameter D of the cylinder is 0.2. The ratio of the minor axis d2 of the semi-ellipse to the diameter of the cylinder affects the depth and curvature of the groove. The ratio of the minor axis d2 of the semi-ellipse to the diameter D of the cylinder can make the airflow generate appropriate centrifugal force and pressure changes in the groove, further promote the development of tumble flow, increase the initial strength of tumble flow, and provide a basis for forming a stable and high-intensity tumble flow in the entire combustion chamber, thereby improving combustion efficiency.

[0062] In some embodiments, the distance h1 from the junction of the top revolving groove 22 and the bottom revolving 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 revolving groove 22 and the bottom revolving 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 revolving groove 22 and the bottom revolving groove 21 to the top surface of the piston 10 is 8 mm, 10 mm, 12 mm, or 14 mm.

[0063] The limitation of the distance from the junction of the top revolving groove 22 and the bottom revolving groove 21 to the top surface of the piston 10 affects the initial state of the mixture when it enters the combustion chamber pit 20. Controlling the distance h1 from the junction of the top revolving groove 22 and the bottom revolving groove 21 to the top surface of the piston 10 within the above range can make the mixture have an appropriate speed and pressure when entering the pit 20, avoid generating a large impact loss energy, or be restricted from forming a tumble flow, which is conducive to the uniform distribution of the mixture in the combustion chamber, and can also cooperate with the movement of the piston 10 and other structures to promote the formation and development of the tumble flow, improve the combustion efficiency, and also take into account the rationality of the structure of the piston 10 and the optimization of the overall performance.

[0064] Through three-dimensional simulation calculation, a comparison is made between the conventional combustion chamber scheme and the combustion chamber scheme of the present invention.

[0065] Figure 7: This is a comparison diagram of the tumble ratio in the cylinder of a conventional combustion chamber and the combustion chamber of this embodiment, wherein the solid line is the conventional combustion chamber and the dotted line is 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 time is between 330°CA and 360°CA. By comparison, it can be seen that in the intake stroke, the swirl ratio of the combustion chamber of this embodiment is significantly higher than that of the conventional combustion chamber.

[0066] Fig. 9 : is a comparison diagram of the velocity field in the combustion chamber cylinder of a conventional combustion chamber and the combustion chamber of this embodiment during the intake process, wherein the left side is the conventional combustion chamber and the right side is the combustion chamber of this embodiment. It can be seen that in the intake stroke of the combustion chamber of this embodiment, the airflow enters the combustion chamber from the intake valve (first intake valve 30 and second intake valve 31) side (top left in the figure), and most of the gas moves toward the exhaust valve (first exhaust valve 32, second exhaust valve 33) side (top right in the figure), then flows down along the wall, flows out through the pit 20, and flows up along the wall to the vicinity of the intake valve (first intake valve 30 and second intake valve 31), and finally forms a tumble flow. In the conventional combustion chamber, in the intake stroke, the airflow enters the combustion chamber from the intake valve (top left in the figure), and most of the gas moves toward the exhaust valve side (top right in the figure), but no tumble flow is formed.

[0067] During the compression stroke, it can be seen that the tumble ratio of the combustion chamber of the present invention has an obvious improvement process, such as Figure 6 shown.

[0068] Fig.10 1 is a comparison diagram of the velocity field in the combustion chamber cylinder 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 flow in the cylinder of the conventional combustion chamber is relatively chaotic.

[0069] Figure 8 is a comparison diagram of the turbulent kinetic energy in the cylinder of the 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 of this embodiment near the ignition moment is increased by about 1 times compared with 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] An embodiment of the present invention further provides an engine, comprising a cylinder, a piston 10 and a combustion chamber according to any of the above embodiments, wherein the combustion chamber is located between the cylinder and the piston 10 .

[0071] In this embodiment, the engine includes the combustion chamber structure of the above embodiment, so that the engine has optimized combustion performance. The structural design of the combustion chamber plays a key role in the operation of the engine. During the intake stroke, the combustion chamber structure can guide the mixture to form a tumble flow that is conducive to combustion, thereby improving the mixing degree and combustion speed of the mixture. During the compression stroke, the shape of the combustion chamber and the airflow guiding characteristics help to further enhance the tumble intensity, making the mixture more uniform during the compression process, and increasing the temperature and pressure of the mixture at the end of compression, creating good conditions for efficient combustion. During the combustion and exhaust processes, the combustion chamber structure can also ensure the stability of the combustion process and the smoothness of exhaust gas discharge, thereby reducing the energy consumption of the engine, improving the overall performance of the engine, and meeting the requirements for engine power and economy.

[0072] Furthermore, if Figure 1 As shown, in the case where the combustion chamber includes a pair of guide grooves 23, the portion of the peripheral wall of the top revolving groove 22 located between the pair of guide grooves 23 constitutes a pair of positive airflow guide portions 25, and the pair of positive airflow guide portions 25 are symmetrically arranged about a plane passing through the axis of the piston 10 (i.e., the second plane M2 mentioned above).

[0073] Therefore, during the intake process, the forward airflow guide 25 can more accurately guide the airflow entering from the intake valve to a specific direction, thereby enhancing the directionality and controllability of the intake airflow in the combustion chamber. The symmetrical arrangement ensures the consistency and balance of the intake airflow on both sides during the guidance process, so that the intake airflow can more effectively form a regular tumble flow in the combustion chamber. This precise airflow guidance improves the uniformity of combustion, enables the mixture to burn more fully, and thus improves the combustion efficiency. At the same time, it cooperates with other structures to jointly optimize the combustion process of the engine.

[0074] The working principle of the engine of 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. Generally, the tangential air passage will cause the intake air flow velocity to the first exhaust valve 32 and the second exhaust valve 33 to be higher, and the intake air with high flow velocity 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 reaches the piston 10 along the cylinder wall. The gas located at the center of the cylinder first enters the inner side of the forward airflow guide 25, and the matching structure of the top revolving groove 22 and the bottom revolving groove 21 can reduce the kinetic energy loss of the gas turning to enter. The bottom revolving groove 21 guides the gas to the other end of the piston 10, and the forward airflow guide 25 located on the other side of the piston 10 ejects the gas in the direction of the first intake valve 30 and the second intake valve 31. In this way, the airflow is turned 180 degrees, so that the gas flows in the direction of the first intake valve 30 and the second intake valve 31, forming a tumble flow in the cylinder.

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

[0077] During the compression process, the piston 10 moves upward, the flow guiding effect of the combustion chamber is further strengthened, and the tumble flow intensity is further increased. Before reaching the compression top dead center, the high-intensity tumble flow is broken into high-intensity turbulent kinetic energy. Finally, at the time of ignition, the turbulent kinetic energy in the cylinder is maximized, the combustion speed is accelerated, and the thermal efficiency is improved.

[0078] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A combustion chamber, characterized in that: Applied to an engine, the engine comprises a cylinder and a piston, the combustion chamber comprises a recess located on the top of the piston, the recess comprises: A bottom revolving groove, wherein the revolving center of the bottom revolving groove is colinear with the axis of the piston, the central cross section of the bottom revolving groove is semi-elliptical, and the major axis of the semi-ellipse is along the radial direction of the piston; The top revolving groove is connected to the bottom revolving groove, the revolving center of the top revolving groove is colinear with the axis of the piston, and the top revolving groove forms an opening at the top of the piston.

2. The combustion chamber according to claim 1, characterized in that Also includes: A pair of guide grooves are symmetrically arranged about the axis of the piston and are disposed on both sides of the top rotary groove along the radial direction of the piston. The guide groove is connected to the top rotary groove along one radial side of the piston, and the guide groove extends to the side wall of the piston along the other radial side of the piston. The guide groove extends to the top surface of the piston along one axial side of the piston.

3. The combustion chamber according to claim 2, characterized in that The engine comprises a first intake valve, a second intake valve, a first exhaust valve and a second exhaust valve, wherein an orthographic projection of the first intake valve on the piston top surface and an orthographic projection of the second intake valve on the piston top surface are symmetrical about a first plane, and an orthographic projection of the first exhaust valve on the piston top surface and an orthographic projection of the second exhaust valve on the piston top surface are symmetrical about the first plane; Wherein, the first plane passes through the rotation centers of the bottom rotation groove and the top rotation groove; Wherein, a pair of the guide grooves are symmetrically arranged about the first plane.

4. The combustion chamber according to claim 3, characterized in that The guide groove extends along the circumference of the piston, and the two ends of the guide groove in the extension direction respectively have guide fillets connecting the groove bottom of the guide groove and the top surface of the piston, and the guide fillets located at the two ends of the guide groove are symmetrical about the second plane; Wherein, the guide fillet gradually inclines from one end close to the outer wall of the piston to one end away from the outer wall of the piston toward a side away from the second plane; The second plane passes through the axis of the piston and is perpendicular to the first plane.

5. The combustion chamber according to claim 4, characterized in that 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 revolving groove and the bottom revolving 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 groove bottom of the guide groove to the top surface of the piston is greater than 0 and less than or equal to 1.

6. The combustion chamber according to claim 4 or 5, characterized in that The side wall of the top revolving groove is tangent to the side wall of the bottom revolving groove; And / or, the angle between the two sides of the cross section of the top revolving groove on the first plane and the long axis of the cross section of the bottom revolving groove on the first plane is greater than or equal to 90° and less than or equal to 120°.

7. The combustion chamber according to any one of claims 1 to 5, 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 diameter D of the cylinder is greater than or equal to 0.1 and less than or equal to 0.

3.

8. The combustion chamber according to any one of claims 1 to 5, characterized in that A distance h1 from a position where the top revolving groove and the bottom revolving groove meet to a top surface of the piston is less than or equal to 20 mm.

9. An engine, characterized in that: The invention comprises a cylinder, a piston and a combustion chamber as claimed in any one of claims 1 to 8, wherein the combustion chamber is located between the cylinder and the piston.

10. The engine according to claim 9, characterized in that In the case where the combustion chamber includes a pair of guide grooves, the portion of the peripheral wall of the top revolving groove located between the pair of guide grooves constitutes a pair of positive airflow guides; A pair of the positive airflow guides are symmetrically arranged about a plane passing through the axis of the piston.

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