CN119664486A - Combustion chamber, engine - Google Patents

Abstract

The application relates to a combustion chamber and an engine. The combustion chamber comprises a pit positioned at the top of the piston, wherein the pit comprises a bottom rotary groove, the rotary center of the bottom rotary groove is collinear with the axis of the piston, the central section of the bottom rotary groove is semi-elliptical, the long axis of the semi-elliptical is along the radial direction of the piston, a top rotary groove is communicated with the bottom rotary groove, the rotary center of the top rotary groove is collinear with the axis of the piston, and an opening is formed in the top of the piston by the top rotary groove. The application can generate more strong tumble than the traditional piston, and improve turbulent energy in the cylinder, thereby accelerating combustion speed and improving thermal efficiency.

Description

Combustion chamber and engine

Technical Field

The application relates to the technical field of engines, in particular to a combustion chamber and an engine.

Background

The gas engine adopts a premixed combustion and spark plug ignition scheme, the combustion speed is related to turbulent energy, and the thermal efficiency can be improved by improving the turbulent energy. The traditional gas engine adopts a vortex air passage based on the improvement of a diesel engine, utilizes the extrusion flow and vortex impact to generate turbulent energy by improving the extrusion area of a piston, but has limited effect and low thermal efficiency.

As the market share of natural gas engines increases, the use of tumble intake to boost turbulence energy is a trend, and how to boost gas engine tumble is an important research direction. Meanwhile, the existing combustion chamber proposal for improving the tumble flow partially has the problems that the shape is limited, the air inlet flow cannot be fully utilized, the processing difficulty is high, the manufacturing cost is high, a cooling oil duct is difficult to be close to, the reliability is greatly influenced by the temperature gradient of a piston, the effect of improving the tumble flow by extrusion flow is limited, the tumble flow is small under the working condition of low rotating speed, and the like.

Disclosure of Invention

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

The application provides a combustion chamber which is applied to an engine and comprises a cylinder and a piston, wherein the combustion chamber comprises a pit positioned at the top of the piston, the pit comprises a bottom rotary groove, the rotary center of the bottom rotary groove is collinear with the axis of the piston, the central section of the bottom rotary groove is semi-elliptical, the long axis of the semi-elliptical is along the radial direction of the piston, a top rotary groove is communicated with the bottom rotary groove, the rotary center of the top rotary groove is collinear with the axis of the piston, and an opening is formed in the top of the piston by the top rotary groove.

According to one embodiment of the application, the piston further comprises a pair of guide grooves which are symmetrically arranged about the axis of the piston and are respectively arranged at two sides of the top turning groove along the radial direction of the piston, wherein one side of the guide grooves along the radial direction of the piston is communicated with the top turning groove, the other side of the guide grooves along the radial direction of the piston extends to the side wall of the piston, and one side of the guide grooves along the axial direction of the piston extends to the top surface of the piston.

According to one embodiment of the application, the engine comprises a first intake valve, a second intake valve, a first exhaust valve and a second exhaust valve, wherein the orthographic projection of the first intake valve on the top surface of the piston is symmetrical with the orthographic projection of the second intake valve on the top surface of the piston 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 with the first plane, wherein the first plane passes through the centers of revolution of the bottom revolution groove and the top revolution groove, and wherein a pair of guide grooves are symmetrically arranged about the first plane.

According to one embodiment of the application, the guide groove extends along the circumferential direction of the piston, two ends of the guide groove in the extending direction are respectively provided with a guide fillet connecting the groove bottom of the guide groove and the top surface of the piston, the guide fillets positioned at the two ends of the guide groove are symmetrical with respect to a second plane, the guide fillets gradually incline from one end close to the outer wall of the piston to one end away from the outer wall of the piston to one side away from the second plane, and the second plane passes through the axis of the piston and is perpendicular to the first plane.

According to one embodiment of the 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 more 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 position where the top turning groove is connected with the bottom turning groove to the top surface of the piston is more than 0 and less than or equal to 1.5, and 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 more than 0 and less than or equal to 1.

According to one embodiment of the application, the side walls of the top turning groove are tangent to the side walls of the bottom turning groove, and/or the angles between the two sides of the cross section of the top turning groove on the first plane and the long axis of the cross section of the bottom turning groove on the first plane are greater than or equal to 90 degrees and less than or equal to 120 degrees.

According to one embodiment of the application, the difference between the diameter D of the cylinder and the long axis D1 of the semi-ellipse is more than or equal to 8mm and less than or equal to 20mm, and the ratio of the short axis D2 of the semi-ellipse to the diameter D of the cylinder is more than or equal to 0.1 and less than or equal to 0.3.

According to one embodiment of the application, the distance h1 between the position where the top turning groove is connected with the bottom turning groove and the top surface of the piston is less than or equal to 20mm.

The application also provides an engine comprising a cylinder, a piston and the combustion chamber of the embodiment, wherein the combustion chamber is positioned between the cylinder and the piston.

According to one embodiment of the present application, in the case where the combustion chamber includes a pair of guide grooves, a portion of the peripheral wall of the top turn groove located between the pair of guide grooves constitutes a pair of forward air flow guide portions, and the pair of forward air flow guide portions are symmetrically disposed with respect to a plane passing through the axis of the piston.

According to the combustion chamber and the engine, after the mixed gas enters the combustion chamber through the pit structure design of the combustion chamber, the mixed gas can flow orderly according to the pit shape and the motion rule of the piston. The center section of the bottom rotary groove is semi-elliptical, and the long axis of the semi-elliptical is along the radial direction of the piston, so that the airflow is guided to generate a certain movement trend in the radial direction of the piston, and the airflow is combined with the movement of the piston to start to lay a foundation for the formation of tumble. The bottom rotary groove, the top rotary groove and the piston axis are collinear, so that the air flow stress is relatively uniform in the piston movement process, and conditions are created for the stable flow and energy conversion of the subsequent air flow in the combustion chamber.

Drawings

Fig. 1 is a schematic structural diagram of a piston according to an embodiment of the present application.

Fig. 2 is a cross-sectional view of a piston provided in an embodiment of the present application.

FIG. 3 is a diagram showing correspondence between a combustion chamber and a first intake valve, a second intake valve, a first exhaust valve and a second exhaust valve according to an embodiment of the present application.

Fig. 4 is a schematic view of a structure of a combustion chamber according to an embodiment of the present application, showing a bottom revolution groove.

Fig. 5 is a schematic view showing a structure of a guide groove in a combustion chamber according to an embodiment of the present application.

FIG. 6 is a schematic view of the airflow guiding function of the guiding slot in the combustion chamber according to an embodiment of the present application.

Fig. 7 is a graph showing the in-cylinder tumble ratio of a conventional combustion chamber and the combustion chamber of the present embodiment.

Fig. 8 is a graph showing the in-cylinder turbulence energy of a conventional combustion chamber compared with that of the combustion chamber of the present embodiment.

Fig. 9 is a graph showing the comparison of the in-cylinder velocity field of a conventional combustion chamber with that of the combustion chamber of the present embodiment during intake.

Fig. 10 is a graph showing a comparison of the in-cylinder velocity field of a conventional combustion chamber and the combustion chamber of the present embodiment in the compression stroke.

Reference numerals:

10. A piston;

20. pit, 21, bottom turning groove, 22, top turning groove, 23, guiding groove, 24, guiding fillet, 25, positive air flow guiding part;

30. first intake valve, 31, second intake valve, 32, first exhaust valve, 33, second exhaust valve;

M1, a first plane, M2, a second plane.

Detailed Description

In order that the above objects, features and advantages of the application will be readily understood, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that, if any, these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., are used herein with respect to the orientation or positional relationship shown in the drawings, these terms refer to the orientation or positional relationship for convenience of description and simplicity of description only, and do not indicate or imply that the apparatus or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.

Furthermore, the terms "first," "second," and the like, if any, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the terms "plurality" and "a plurality" if any, mean at least two, such as two, three, etc., unless specifically defined otherwise.

In the present application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly. For example, they may be fixedly connected, detachably connected or integrally formed, mechanically connected, electrically connected, directly connected or indirectly connected through an intermediate medium, and communicated between two elements or the interaction relationship between two elements unless clearly defined otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present application, unless expressly stated or limited otherwise, the meaning of a first feature being "on" or "off" a second feature, and the like, is that the first and second features are either in direct contact or in indirect contact through an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that if an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. If an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein, if any, are for descriptive purposes only and do not represent a unique embodiment.

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of a piston according to an embodiment of the present application, and fig. 2 is a cross-sectional view of a piston according to an embodiment of the present application.

The combustion chamber of the embodiment of the application is applied to an engine, and the engine comprises a cylinder and a piston 10, wherein the cylinder provides space for the reciprocating motion of the piston 10 and is also a place for the combustion of the mixture. The piston 10 is located inside the cylinder, forms a sealed space with the cylinder wall, and reciprocates up and down during operation of the engine. The combustion chamber is located in the area between the top of the piston 10 and the cylinder head, and is located in a part of the cylinder interior space, and is a key part for generating energy by combustion of the mixture.

The combustion chamber of the present embodiment includes a pit 20 at the top of the piston 10, the pit 20 including a bottom revolution groove 21 and a top revolution groove 22. The center of rotation of the bottom rotation groove 21 is collinear with the axis of the piston 10, the center section of the bottom rotation groove 21 is semi-elliptical, and the long axis of the semi-elliptical is along the radial direction of the piston 10. The top turning groove 22 communicates with the bottom turning groove 21, the turning center of the top turning groove 22 is collinear with the axis of the piston 10, and the top turning groove 22 forms an opening at the top of the piston 10.

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, and gradually decreases in width from the side near the top of the piston 10 to the side away from the top of the piston 10.

The upper end of the top turn 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 turn groove 22 is connected to the upper end of the bottom turn groove 21 to form a continuous pit 20 structure at the upper side of the piston 10.

According to the embodiment, through the structure, after the mixed gas enters the combustion chamber, the mixed gas can flow orderly according to the shape of the pit 20 and the movement rule of the piston 10. The semi-elliptical major axis of the bottom swivel groove 21 is beneficial to guiding the airflow to generate a certain movement trend in the radial direction along the radial direction of the piston 10, and in combination with the movement of the piston 10, the foundation is laid for the formation of the tumble flow. The center lines of the top rotary groove 22 and the bottom rotary groove 21 are collinear with the axis of the piston 10, so that the air flow is relatively uniform in stress during the movement of the piston 10, and conditions are created for the stable flow and energy conversion of the subsequent air flow in the combustion chamber, thereby being beneficial to improving the combustion efficiency.

In addition, the combination of the top turning groove 22 and the bottom turning groove 21 is beneficial to reducing the loss of kinetic energy of the air, specifically, after the air flows into the pit 20 and flows to the other side along the pit 20, the air flows can be more smoothly turned under the guiding projection action of the corresponding side of the bottom turning groove 21 and the corresponding side outer wall of the top turning groove 22, so that the air flows are prevented from vertically colliding with the side wall of the pit 20 to cause larger kinetic energy loss, and the phenomenon that part of the air flows are turned downwards to influence the formation of rolling flows is avoided.

In addition, in the intake cycle, when a mixture of fuel gas and air enters the cylinder through the intake port, the tangential air passage normally causes a higher flow rate of intake air to the exhaust valve side, and the intake air of a high flow rate moves from the intake valve to the exhaust valve side and then reaches the piston 10 along the cylinder wall surface. The gas in the center of the cylinder enters the pit 20 first, and the top rotary groove 22 is arranged above the bottom rotary groove 21, so that the kinetic energy loss caused by gas steering into the pit 20 can be reduced.

In some embodiments of the application, referring to fig. 1, the combustion chamber further includes a pair of guide grooves 23, the pair of guide grooves 23 being symmetrically disposed about the axis of the piston 10 and being disposed on both sides of the top turning groove 22 in the radial direction of the piston 10, the guide grooves 23 communicating with the top turning groove 22 in one side of the radial direction of the piston 10, the guide grooves 23 extending to the side wall of the piston 10 in the other side of the radial direction of the piston 10, the guide grooves 23 extending to the top surface of the piston 10 in one side of the axial direction of the piston 10.

The guide grooves 23 may form symmetrical notches on both sides of the top turn groove 22, which notch locations act as lateral air flow guiding areas, and the guide grooves 23 may guide the air flow from the top turn groove 22 to a wider area, including near the side wall of the piston 10, after the mixture enters the combustion chamber. This guiding action can create a motion component of the gas flow in different positions and directions during movement of the piston 10, enhancing the uniformity of the gas flow distribution within the combustion chamber. The symmetrical arrangement ensures the balance of the airflows at two sides, avoids the local airflow disorder caused by asymmetry, further stabilizes the airflow state in the combustion chamber, provides guarantee for forming regular tumble with higher strength, and further improves the combustion efficiency.

Fig. 3 is a diagram showing correspondence between a combustion chamber and a first intake valve, a second intake valve, a first exhaust valve and a second exhaust valve according to an embodiment of the present application, and dashed lines in fig. 3 indicate orthographic projection positions of the first intake valve, the second intake valve, the first exhaust valve and the second exhaust valve on a top surface of a piston 10.

In some embodiments, in conjunction with FIG. 3, 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 being 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 being symmetrical about the first plane M1, wherein the first plane M1 passes through the centers of revolution of the bottom revolution groove 21 and the top revolution groove 22, and wherein the pair of guide grooves 23 are symmetrically disposed about the first plane M1.

The symmetrical relationship of the engine valve and the guide groove 23 ensures 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, the pair of guide grooves 23 are also symmetrical about the first plane M1, and during the intake process, the symmetrical valve layout enables the mixture gas entering the combustion chamber to be relatively uniformly distributed on both sides in quantity and speed, and the symmetrical structure of the pair of guide grooves 23 can correspondingly guide the intake air flow to different areas in the combustion chamber uniformly, so that the initial condition of tumble formation is ensured to be uniform. In the exhaust process, the same symmetrical relation is beneficial to the uniform exhaust of the exhaust gas, and the influence of residual exhaust gas caused by unsmooth partial exhaust on the next round of air intake and combustion is avoided. This symmetry improves the stability and repeatability of the overall combustion cycle, facilitating improved combustion efficiency and reduced emissions.

Referring to fig. 1, 3 and 6, in some embodiments, the guide groove 23 extends along the circumferential direction of the piston 10, and both ends of the guide groove 23 in the extending direction have guide fillets 24 connecting the groove bottom of the guide groove 23 and the top surface of the piston 10, respectively, and the guide fillets 24 at both ends of the guide groove 23 are symmetrical with respect to the second plane M2, wherein the guide fillets 24 are gradually inclined from one end close to the outer wall of the piston 10 to one end away from the outer wall of the piston 10 to one side away from the second plane M2, and wherein the second plane M2 passes through the axis of the piston 10 and is perpendicular to the first plane M1.

In this embodiment, the guiding groove 23 extends along the circumferential direction of the piston 10 and has guiding fillets 24 at both ends, the special inclined design of the guiding fillets 24 having an important influence on the direction of movement of the air flow and on the energy loss. When the air flow moves to two ends along the circumference of the guide groove 23, the guide fillets 24 can smoothly change the direction of the air flow, so that the energy loss caused by abrupt steering is avoided, and the air flow can keep high kinetic energy to continue to move in the combustion chamber. Meanwhile, the rounded corners gradually incline from the end close to the outer wall of the piston 10 to the end far away from the outer wall to the side far away from the second plane M2, so that the air flow moving in the circumferential direction is corrected. Under the combined action of the movement of the piston 10 and the intake air flow, the circumferential air flow is easy to generate vortex, but the guiding fillets 24 can adjust the circumferential speed component of the air flow, reduce the formation of vortex, convert more air flow energy into tumble favorable for combustion, improve the quality and strength of the tumble and promote the more complete combustion of the mixed gas.

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 0.5 or more and 0.9 or less. 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 0.7 or more and 0.8 or less, 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.

The range of the ratio of the length L1 of the guide groove 23 projected in the direction of the first plane M1 to the cylinder diameter D affects the range of the guide of the air flow. 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 within the above-mentioned interval range, so that the airflows at different positions in the radial direction of the cylinder can be effectively guided, and the local airflow runaway caused by the overlong or excessively short length can be avoided.

Alternatively, 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 position where the top turning groove 22 meets the bottom turning groove 21 to the top surface of the piston 10 is greater than 0 and equal to or less than 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 position where the top turning groove 22 meets the bottom turning 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 position where the top turning groove 22 meets the bottom turning groove 21 to the top surface of the piston 10 is 1. The ratio range of the distance from the bottom of the guide groove 23 to the top surface of the piston 10 to the distance from the position where the top turning groove 22 and the bottom turning groove 21 are connected to the top surface of the piston 10 determines the flow space and speed change of the air flow in different height areas. In the interval range, the airflow can form ordered speed gradients among different height layers, so that the mixing and energy transfer of the airflow in the vertical direction are promoted, and a stable tumble structure is formed.

Alternatively, the ratio of the diameter r1 of the guide rounded corner 24 to the distance h2 from the bottom of the 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 rounded 24 to the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 is 0.4 or more and 0.6 or less, for example, the ratio of the diameter r1 of the guide rounded 24 to the distance h2 from the bottom of the guide groove 23 to the top surface of the piston 10 is 0.5.

The ratio range of the diameter r1 of the guiding fillet 24 to the width of the orthographic projection of the guiding groove 23 in the direction of the first plane M1 further precisely controls the flow characteristics of the air flow in the local area, can reduce the energy loss of the air flow in the turning and flowing process, optimize the integral distribution of the air flow in the combustion chamber, and improve the stability and strength of the tumble flow, thereby improving the combustion efficiency.

In some embodiments, the sidewalls of the top swivel groove 22 are tangential to the sidewalls of the bottom swivel groove 21. The tangential relationship of the top turning groove 22 and the bottom turning groove 21 allows for smoother airflow when transitioning between the two. When the air flow enters the top turning groove 22 from the bottom turning groove 21, the tangential design avoids air flow disturbance and energy loss caused by abrupt structural change, and ensures the continuity and stability of the air flow.

Alternatively, the angles between the both sides of the cross section of the top turn groove 22 on the first plane M1 and the long axis of the cross section of the bottom turn groove 21 on the first plane M1 are 90 ° or more and 120 ° or less, that is, the angles α between the extended lines of the both sides of the cross section of the top turn groove 22 on the first plane M1 and the long axis of the cross section of the bottom turn groove 21 on the first plane M1 are 60 ° or more and 90 ° or less.

The range of angles between the two sides of the cross section of the top turn groove 22 on the first plane M1 and the long axis of the cross section of the bottom turn groove 21 on the first plane M1 affects the flow path and the speed variation of the mixture between these two regions. The range of the included angles between the two sides of the cross section of the top rotary groove 22 on the first plane M1 and the long axis of the cross section of the bottom rotary groove 21 on the first plane M1 can guide the airflow to flow in different areas at proper angles and speeds, and adjust the direction and energy distribution of the airflow, so that the airflow is more beneficial to the formation and development of the tumble flow. The structural relationship optimizes the flowing process of the mixed gas in the combustion chamber, improves the tumble effect, promotes the full combustion of the mixed gas and further improves the combustion efficiency.

In some embodiments, referring to fig. 2, 4 and 5, the difference between the diameter D of the cylinder and the major axis D1 of the semi-ellipse is 8mm or more and 20mm or less, preferably, the difference between the diameter D of the cylinder and the major axis D1 of the semi-ellipse is 12mm or more and 16mm or less, for example, the difference between the diameter D of the cylinder and the major axis D1 of the semi-ellipse is 14mm or 15mm. The difference between the diameter D of the cylinder and the long axis D1 of the semi-ellipse makes the space layout of the bottom rotary groove 21 in the cylinder more reasonable, and can adapt to the flow and speed requirements of the mixed gas under different working conditions. In the air inlet process, the groove shape determined according to the long axis difference value can guide the airflow to form a specific flow mode, and is beneficial to the generation of initial tumble.

Alternatively, the ratio of the semi-elliptical short axis D2 to the diameter D of the cylinder is 0.1 or more and 0.3 or less, for example, the ratio of the semi-elliptical short axis D2 to the diameter D of the cylinder is 0.2. The ratio of the semi-elliptical short shaft to the diameter of the cylinder influences the depth and the curvature of the groove, and the ratio of the semi-elliptical short shaft D2 to the diameter D of the cylinder can enable the airflow to generate proper centrifugal force and pressure change in the groove, further promote the development of tumble flow, improve the initial strength of the tumble flow, provide a basis for forming stable and high-strength tumble flow in the whole combustion chamber, and further improve the combustion efficiency.

In some embodiments, the distance h1 from the position where the top turning groove 22 meets the bottom turning groove 21 to the top surface of the piston 10 is 20mm or less, and preferably, the distance h1 from the position where the top turning groove 22 meets the bottom turning groove 21 to the top surface of the piston 10 is 8mm or more and 15mm or less. For example, the distance h1 from the position where the top turning groove 22 meets the bottom turning groove 21 to the top surface of the piston 10 is 8mm, 10mm, 12mm, 14mm, or the like.

The limitation of the distance from the location where the top turning groove 22 meets the bottom turning groove 21 to the top surface of the piston 10 affects the initial state of the mixture entering the combustion chamber pocket 20. The distance h1 from the connection position of the top rotary groove 22 and the bottom rotary groove 21 to the top surface of the piston 10 is controlled in the above interval, so that the mixed gas has proper speed and pressure when entering the pit 20, the generation of larger impact loss energy is avoided, or the mixed gas is limited and cannot form a tumble, the uniform distribution of the mixed gas in the combustion chamber is facilitated, the mixed gas can also cooperate with the movement of the piston 10 and other structures, the formation and development of the tumble are promoted, the combustion efficiency is improved, and the optimization of the rationality and the overall performance of the structure of the piston 10 is also considered.

The conventional combustion chamber scheme and the combustion chamber scheme of the invention are compared through three-dimensional simulation calculation.

Fig. 7 is a graph of in-cylinder tumble ratio comparison of a conventional combustion chamber and a combustion chamber of the present embodiment, wherein a solid line is a conventional combustion chamber and a broken line is a combustion chamber of the present application. The intake stroke is 0 ° CA to 180 ° CA, the compression stroke is 180 ° CA to 360 ° CA, and the ignition timing is between 330 ° CA to 360 ° CA. As can be seen by comparison, the swirl ratio of the combustion chamber of this embodiment is significantly higher than that of a conventional combustion chamber during the intake stroke.

Fig. 9 is a graph showing the comparison of the velocity field in the cylinder of the conventional combustion chamber with that of the combustion chamber of the present embodiment during the intake process, wherein the left side is the conventional combustion chamber and the right side is the combustion chamber of the present embodiment. It can be seen that the combustion chamber of the present embodiment is in the intake stroke, and the air flow enters the combustion chamber from the intake valve (first intake valve 30 and second intake valve 31) side (top left in the drawing), and most of the air moves toward the exhaust valve (first exhaust valve 32, second exhaust valve 33) side (top right in the drawing), and then flows down along the wall surface, flows out through the pit 20, up along the wall surface, reaches the vicinity of the intake valves (first intake valve 30 and second intake valve 31), and finally forms a tumble flow. Whereas a conventional combustion chamber is in the intake stroke, the gas flow enters the combustion chamber from the intake valve (top left in the figure), most of the gas moves toward the exhaust valve side (top right in the figure), but no tumble flow is formed.

During the compression stroke, a significant increase in tumble ratio of the combustion chamber of the present invention can be seen, as shown in fig. 6.

Fig. 10 is a graph showing a comparison of the in-cylinder velocity field of a conventional combustion chamber and the combustion chamber of the present embodiment in the compression stroke. It can be seen that the tumble flow of the combustion chamber of the present embodiment is already irregular, whereas the in-cylinder flow of the conventional combustion chamber is chaotic.

Fig. 8 is a graph comparing the in-cylinder turbulence energy of a conventional combustion chamber with that of the combustion chamber of the present embodiment, and it can be seen from fig. 8 that the turbulence energy of the combustion chamber of the present embodiment in the vicinity of the ignition timing is improved by about 1 time compared with that of the conventional combustion chamber, which indicates that the tumble flow in the combustion chamber of the present embodiment can be broken into turbulence of a smaller scale in the vicinity of the ignition timing.

The embodiment of the invention also provides an engine comprising a cylinder, a piston 10 and a combustion chamber according to any of the embodiments described above, the combustion chamber being located between the cylinder and the piston 10.

In this embodiment, the engine includes the combustion chamber structure of the above embodiment, so that the engine has an optimized combustion performance. The structural design of the combustion chamber plays a key role in the operation of the engine. In the intake stroke, the combustion chamber structure can guide the mixed gas to form tumble favorable for combustion, so that the mixing degree and the combustion speed of the mixed gas are improved. In the compression stroke, the shape and the air flow guiding characteristic of the combustion chamber are beneficial to further enhancing the tumble strength, so that the mixed gas is more uniform in the compression process, the temperature and the pressure of the mixed gas at the end of compression are improved, and good conditions are created for efficient combustion. In 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, so that the energy consumption of the engine is reduced, the overall performance of the engine is improved, and the requirements on the power performance and the economy of the engine are met.

Further, as shown in fig. 1, in the case where the combustion chamber includes a pair of guide grooves 23, a portion of the peripheral wall of the top turn groove 22 located between the pair of guide grooves 23 constitutes a pair of forward air flow guide portions 25, and the pair of forward air flow guide portions 25 are symmetrically disposed with respect to a plane passing through the axis of the piston 10 (i.e., the above-described second plane M2).

Thus, during intake, the forward airflow guide portion 25 can guide the airflow entering from the intake valve more accurately in a specific direction, enhancing the directionality and controllability of the intake airflow in the combustion chamber. The symmetrical arrangement ensures the consistency and balance of the intake airflows at the two sides in the guiding process, so that the intake airflows can form regular tumble in the combustion chamber more effectively. The accurate air flow guide improves the combustion uniformity, so that the mixed gas can be combusted more fully, the combustion efficiency is improved, and meanwhile, the mixed gas is matched with other structures, so that the combustion process of the engine is optimized together.

The engine of this embodiment operates as follows:

In the intake cycle, a 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. In general, the tangential air passage causes the flow rate of the intake air to the first exhaust valve 32 and the second exhaust valve 33 to be higher, and the intake air of a high flow rate 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 surface. The gas at the center of the cylinder advances into the inside of the forward gas flow guide portion 25, and the matching structure of the top turning groove 22 and the bottom turning groove 21 can reduce the kinetic energy loss of the gas turning into. The bottom turning groove 21 guides the gas to the other end of the piston 10, and the forward gas flow guide 25 located at the other side of the piston 10 projects the gas in the direction of the first intake valve 30 and the second intake valve 31. This causes a 180 degree turn of the gas flow, which causes the gas to flow in the direction of the first and second intake valves 30 and 31, forming a tumble flow in the cylinder.

The air at the two sides of the air cylinder enters the guide groove 23, and the direction of the air flow is changed by using the guide fillets 24 at the two ends of the guide groove 23, so that the kinetic energy loss caused by the change of the direction of the air flow is reduced. Meanwhile, for the airflow moving in the circumferential direction, the guide fillets 24 have a certain correction effect, so that the eddy current in the cylinder is reduced, and the rolling flow in the cylinder is improved.

During compression, the piston 10 is moved upward, the flow guiding effect of the combustion chamber is further enhanced, and the tumble strength is further increased. Before reaching compression top dead center, the high intensity tumble flow breaks into high intensity turbulent energy. Finally, during ignition, turbulence energy in the cylinder is maximized, the combustion speed is accelerated, and the thermal efficiency is improved.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (10)

1. A combustion chamber for an engine, the engine comprising a cylinder and a piston, the combustion chamber comprising a pit in a top of the piston, the pit comprising:

The center of the bottom rotary groove is collinear with the axis of the piston, the center section of the bottom rotary groove is semi-elliptical, and the long axis of the semi-elliptical is along the radial direction of the piston;

The top rotary groove is communicated with the bottom rotary groove, the rotary center of the top rotary groove is collinear with the axis of the piston, and an opening is formed in the top of the piston by the top rotary groove.

2. The combustor as set forth in claim 1, further comprising:

The guide grooves are symmetrically arranged on the axis of the piston and are respectively arranged on two sides of the top turning groove along the radial direction of the piston, one side of the guide grooves along the radial direction of the piston is communicated with the top turning groove, the other side of the guide grooves along the radial direction of the piston extends to the side wall of the piston, and one side of the guide grooves along the axial direction of the piston extends to the top surface of the piston.

3. The combustion chamber of claim 2 wherein the engine comprises 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 piston top surface and the orthographic projection of the second intake valve on the piston top surface being symmetrical about a first plane, and the orthographic projection of the first exhaust valve on the piston top surface and the orthographic projection of the second exhaust valve on the piston top surface being symmetrical about the first plane;

Wherein the first plane passes through the centers of revolution of the bottom revolution groove and the top revolution groove;

wherein a pair of the guide grooves are symmetrically disposed about the first plane.

4. A combustion chamber according to claim 3, wherein the guide groove extends in the circumferential direction of the piston, and both ends in the extending direction of the guide groove are respectively provided with guide fillets connecting the bottom of the guide groove and the top surface of the piston, the guide fillets at both ends of the guide groove being symmetrical with respect to a second plane;

the guide fillet is gradually inclined from one end close to the outer wall of the piston to one end away from the outer wall of the piston to one side away from the second plane;

Wherein 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, wherein a ratio of a length L1 of orthographic projection of the guide groove in the first plane direction to a diameter D of the cylinder is 0.5 or more and 0.9 or less;

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 joint position of the top rotary groove and the bottom rotary groove to the top surface of the piston is more 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 more than 0 and less than or equal to 1.

6. The combustor of claim 4 or 5, wherein a sidewall of the top turn groove is tangential to a sidewall of the bottom turn groove;

And/or, the included angle between the two sides of the cross section of the top rotary groove on the first plane and the long axis of the cross section of the bottom rotary groove on the first plane is more than or equal to 90 degrees and less than or equal to 120 degrees.

7. The combustion chamber according to any one of claims 1 to 5, wherein a difference between a diameter D of the cylinder and a major axis D1 of the semi-elliptical shape is 8mm or more and 20mm or less;

The ratio of the semi-elliptical short axis D2 to the diameter D of the cylinder is more than or equal to 0.1 and less than or equal to 0.3.

8. The combustion chamber of any one of claims 1 to 5, wherein a distance h1 from a position where the top turning groove meets the bottom turning groove to a top surface of the piston is 20mm or less.

9. An engine comprising a cylinder, a piston and a combustion chamber as claimed in any one of claims 1 to 8, the combustion chamber being located between the cylinder and the piston.

10. The engine according to claim 9, wherein in the case where the combustion chamber includes a pair of guide grooves, a portion of a peripheral wall of the top turn groove located between the pair of guide grooves constitutes a pair of forward air flow guides;

a pair of the forward airflow guides are symmetrically disposed about a plane passing through the axis of the piston.