Vector air inlet-space injection combustion system of opposed-piston two-stroke diesel engine

Abstract

The invention provides an opposed piston two-stroke diesel engine vector air inlet-space injection combustion system which comprises an air cylinder sleeve, an air inlet piston, an exhaust piston and a plurality of oil injectors, and the air inlet piston, the exhaust piston and the inner wall of the air cylinder sleeve are matched to form a combustion chamber. A plurality of vector air inlets and exhaust ports are formed in the positions, close to the air inlet piston and the exhaust piston, of the air cylinder sleeve respectively, each vector air inlet is composed of a direct-flow air port and a vortex air port, and the direct-flow air ports and the vortex air ports are arranged at intervals in the circumferential direction; the number of the oil sprayers is two, and the two oil sprayers are arranged on the center face of the air cylinder sleeve in a staggered mode so that the oil sprayers can be arranged in a reverse vortex mode. The problems that an opposed piston two-stroke diesel engine is insufficient in combustion, low in scavenging efficiency and the like are solved, oil and gas in a cylinder can be rapidly and sufficiently mixed through the system, the combustion process is effectively accelerated, combustion in the cylinder is more sufficient, and the combustion efficiency is improved.

Description

Technical Field

[0001] The present application belongs to the field of engine combustion technology, and in particular relates to an opposed-piston two-stroke diesel engine vector intake-space injection combustion system. Background Art

[0002] Compared with traditional four-stroke diesel engines, opposed-piston two-stroke diesel engines eliminate the cylinder head and valve mechanism, significantly reducing the size and weight of the engine. At the same time, it reduces the heat dissipation area of the engine, thereby reducing the amount of heat dissipated to the cooling system. It has the advantages of high power density and low specific heat dissipation.

[0003] Because it is a two-stroke engine, its scavenging time is short and the intake and exhaust processes are carried out simultaneously, resulting in problems such as a large residual exhaust gas coefficient in the cylinder and poor scavenging quality; the multi-injector arrangement easily causes collision of fuel sprays or oil beams hitting the inner wall of the cylinder liner, limiting the development of the oil beam and affecting the oil-gas mixing process. In addition, due to the short combustion duration of the two-stroke engine, it leads to problems such as incomplete combustion and high fuel consumption. Summary of the Invention

[0004] In view of this, the present application aims to propose a vector intake-space injection combustion system for an opposed-piston two-stroke diesel engine to solve the problems of incomplete combustion and low scavenging efficiency in the opposed-piston two-stroke diesel engine.

[0005] To achieve the above objectives, the technical solution of this application is implemented as follows: The present application provides a vectored intake and spatial injection combustion system for an opposed-piston two-stroke diesel engine, comprising a cylinder liner, an intake piston, an exhaust piston, and a plurality of fuel injectors. The intake piston and the exhaust piston cooperate with the inner wall of the cylinder liner to form a combustion chamber. The cylinder liner is provided with a plurality of vectored intake ports and exhaust ports near the intake piston and the exhaust piston, respectively. The vectored intake ports are composed of straight-flow ports and vortex ports, and the straight-flow ports and the vortex ports are arranged circumferentially at intervals. There are two fuel injectors, which are staggered and arranged at the center plane of the cylinder liner to form a reverse vortex arrangement of the fuel injectors.

[0006] Furthermore, in a cross section perpendicular to the piston movement direction, two side edges of the direct current air port form an included angle, and in a cross section along the piston movement direction, the direct current air port forms an elevation angle.

[0007] Furthermore, the vortex air port is configured with an air intake inclination angle, wherein the air intake inclination angle in the direction of the air flow is greater than the air port inclination angle in the direction against the air flow.

[0008] Furthermore, with the horizontal plane of the cylinder liner as a reference, the offset distances between the two injectors and the horizontal plane of the cylinder liner are equal.

[0009] Furthermore, the fuel injector is provided with a plurality of spray holes, one of the spray holes is located on the central axis of the fuel injector, and the remaining spray holes form a spatial angle with the central axis of the fuel injector.

[0010] Furthermore, the top surfaces of the intake piston and the exhaust piston are both in the shape of a shallow pit, and an oil injection notch is provided at the piston fire land, and the oil injection notch is conical.

[0011] Furthermore, the diameters of the intake piston and the exhaust piston are both in the range of 80 mm to 140 mm.

[0012] Compared with the prior art, the opposed-piston two-stroke diesel engine vectored intake-space injection combustion system described in this application has the following beneficial effects: (1) The vectored air inlet provided in the present application can improve the airflow movement at the cylinder wall surface and reduce the exhaust gas retention at the cylinder wall surface. The tumble effect generated by the appropriate elevation angle can increase the turbulent kinetic energy in the cylinder and strengthen the subsequent oil-gas mixing process. At the same time, due to the different inclination angles of the vortex air inlet in the direction of the airflow and the direction of the reverse airflow, the intake difference between the left and right intake ducts can be reduced, and the problem of one-sided scavenging and serious deviation of the scavenging center can be effectively solved. (2) The present application adopts two staggered injectors and optimizes the arrangement angle of the spray holes. A part of the oil beam is in the opposite direction to the vortex formed in the cylinder. This reverse impact of the airflow and the spray can optimize the spray distribution and make full use of the air at the edge of the cylinder. The other part of the oil beam is in the same direction as the vortex formed in the cylinder, which can further enhance the vortex intensity in the cylinder, promote the atomization of the injection, improve combustion, and avoid excessive interference between multiple injection beams, which is beneficial to the conversion between injection energy and turbulent kinetic energy. (3) The vortex and tumble formed in the cylinder of the present application, combined with the spatial oil beam distribution, allows the oil and gas in the cylinder to be quickly and fully mixed, and prevents the flame from deviating from the center of the combustion chamber, reducing the heat transfer loss to the cylinder wall; at the same time, the tumble organized in the cylinder is broken up near the top dead center and converted into turbulent kinetic energy, which can effectively accelerate the combustion process, make the combustion in the cylinder more complete, and improve the combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings: Figure 1 This is a schematic structural diagram of a vectored intake-space injection combustion system for an opposed-piston two-stroke diesel engine according to an embodiment of the present application; Figure 2 Schematic diagram of two structural forms of the vector air inlet described in the embodiments of this application; Figure 3This is a schematic diagram of the definition of the elevation angle of the direct current air outlet described in the embodiment of the present application; Figure 4 Schematic diagram of the arrangement of the fuel injector according to the embodiment of the present application; Figure 5 Schematic diagram of the nozzle arrangement according to the embodiment of the present application; Figure 6 It is a schematic diagram of the combustion chamber shape and oil beam distribution on the top surface of the intake and exhaust pistons described in an embodiment of the present application.

[0014] Description of reference numerals: 1-Cylinder liner; 2-Vector air intake; 3-Intake piston; 4-Exhaust piston; 5-Exhaust port; 6-Injector. DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0016] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the usual meanings understood by people with ordinary skills in the field to which this application belongs. The "first", "second" and similar words used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] See also Figure 1 As shown, this embodiment provides an opposed-piston two-stroke diesel engine vectored intake-spatial injection combustion system, comprising a cylinder liner, an intake piston, an exhaust piston, and multiple injectors. The intake piston, the exhaust piston, and the inner wall of the cylinder liner cooperate to form a combustion chamber. The diameters of the intake piston and the exhaust piston are both in the range of 80 mm to 140 mm. The cylinder liner is provided with a plurality of vectored intake ports and exhaust ports near the intake piston and the exhaust piston, respectively. The vectored intake ports are composed of straight-flow ports and vortex ports, which are arranged circumferentially at intervals. There are two fuel injectors, which are staggered and arranged at the center plane of the cylinder liner to form a reverse vortex arrangement of the fuel injectors.

[0018] This application solves the problems of incomplete combustion and low scavenging efficiency in opposed-piston two-stroke diesel engines. The system can quickly and fully mix the oil and gas in the cylinder, effectively accelerate the combustion process, make the combustion in the cylinder more complete, and improve combustion efficiency.

[0019] In some embodiments, in a cross section perpendicular to the direction of piston movement, two side edges of the straight flow port form an angle, and in a cross section along the direction of piston movement, the straight flow port forms an elevation angle; The vortex air port is configured with an air intake inclination angle, wherein the air intake inclination angle in the direction of the air flow is greater than the air port inclination angle in the direction against the air flow.

[0020] Specifically, in this embodiment, the specific structure of the vector air inlet is shown in the figure. The air inlets are divided into two types, which are evenly and intermittently arranged in a horizontal plane at one end of the center plane of the cylinder liner.

[0021] Among them, one type of air port is a direct current air port. In the cross section perpendicular to the direction of piston movement, the left and right sides of the direct current air port form a certain angle θ, similar to a nozzle, which can accelerate the air flow and speed up the scavenging; in the cross section along the direction of piston movement, it has a certain elevation angle β (the definition of elevation angle β is shown in Figure 3 ), while ensuring the intake volume, a certain degree of tumble can be generated.

[0022] Another structure of the air port is the vortex air port, such as Figure 2 As shown in the figure, the intake inclination angle α of the vortex air port in the right intake duct along the airflow direction is relatively large, and the intake inclination angle α of the vortex air port in the left intake duct against the airflow direction is relatively small, which can reduce the intake difference between the left and right intake ducts and effectively solve the problem of single-sided scavenging and serious deviation of the scavenging center; the intake inclination angles of the left and right sides of each vortex air port are different (such as Figure 2 As shown in the figure, α1>α2, α3>α4). Like a direct current port, this nozzle-like design accelerates the airflow and speeds up scavenging. Simultaneously, the tumble and vortex formed within the cylinder combine to form an oblique-axis vortex, which improves airflow motion at the cylinder wall, reduces exhaust gas retention there, and enhances scavenging efficiency.

[0023] In some embodiments, with the cylinder liner horizontal plane as a reference, the offset distances between the two injectors and the cylinder liner horizontal plane are equal.

[0024] Specifically, in this embodiment, the vectored air inlet and exhaust ports are arranged on the horizontal planes at both ends of the cylinder liner center plane. The two air port structures of the vectored air inlet are evenly and intermittently arranged on the horizontal plane at one end of the cylinder liner center plane. The distance between each vectored air inlet and the cylinder liner center plane is consistent. The exhaust ports are circumferentially arranged on a horizontal plane at the other end of the center plane of the cylinder liner, and the distance between each exhaust port and the center plane of the cylinder liner is consistent.

[0025] In some embodiments, the fuel injector is provided with a plurality of spray holes, one of which is located on the central axis of the fuel injector, and the remaining spray holes form a spatial angle with the central axis of the fuel injector.

[0026] Specifically, in this embodiment, the two injectors are staggered and arranged at the center plane of the cylinder liner. The two injectors distributed at the center plane of the cylinder liner are offset downward and upward by h respectively based on the horizontal plane of the cylinder liner. The specific arrangement is shown in FIG. Figure 4 .

[0027] This embodiment is explained by taking each injector having three spray holes as an example. Figure 5 As shown in the two views of the injector, the parameters a, b, and c are used to define the nozzle position. Figure 6 As shown in the figure, the black arrow represents the oil beam with the nozzle parameters a and b both being 0°. The direction of this oil beam is opposite to the vortex formed in the cylinder. This reverse impact of the airflow and the spray can optimize the spray distribution and make full use of the air at the edge of the cylinder. The red arrow represents the oil beam with the nozzle parameters a and b being a certain value (not 0). It is in the same direction as the vortex formed in the cylinder, which can further enhance the vortex intensity in the cylinder, promote fuel atomization, and improve combustion. At the same time, the spatial oil beam distribution formed can avoid excessive interference between multiple injection beams, which is beneficial to the conversion between injection energy and turbulent kinetic energy and improves combustion performance.

[0028] In some embodiments, the top surfaces of the intake piston and the exhaust piston are both in the shape of a shallow pit, and an oil injection notch is provided at the piston fire land, and the oil injection notch is conical.

[0029] Specifically, in this embodiment, the combustion chamber is composed of the top surface of the intake piston, the top surface of the exhaust piston, and the cylinder wall. The shape of the combustion chamber is mainly determined by the top surface of the intake and exhaust pistons. The top surface of the intake and exhaust pistons is designed to be shallowly pitted. To prevent oil mist from hitting the piston firing land, an injection notch is designed on the firing land. Based on the orientation of the injector nozzle and the injection penetration distance, the injection notch is designed to be conical. The specific structure of the combustion chamber is shown in FIG. Figure 6 .

[0030] The vortex and tumble formed in the cylinder, combined with the complex spatial oil beam distribution, enable the oil and gas in the cylinder to mix quickly and fully, improving combustion; at the same time, the tumble organized in the cylinder is broken up near the top dead center and converted into turbulent kinetic energy, which can effectively accelerate the combustion process, make the combustion in the cylinder more complete, and improve combustion efficiency.

[0031] The working principle of a vector intake-spatial injection combustion system of an opposed-piston two-stroke diesel engine is as follows: air enters the cylinder through a vector intake port, and under the action of two intermittently distributed air ports, tumble and vortex of a certain intensity are organized to form in the cylinder. The tumble and vortex are combined into an oblique-axis vortex, which can improve the airflow movement at the cylinder wall and reduce the exhaust gas retention at the cylinder wall. The tumble effect produced by a moderate elevation angle can increase the turbulent kinetic energy in the cylinder and strengthen the subsequent oil-gas mixing process. Since the inclination angles of the vortex air ports in the direction of airflow and against the direction of airflow are different, the intake difference between the left and right intake ducts can be reduced, and the problems of one-sided scavenging and serious deviation of the scavenging center can be effectively solved, thereby improving the scavenging efficiency.

[0032] By optimizing the arrangement of the spray holes, the oil beams sprayed by the two injectors form a complex spatial oil beam, avoiding excessive interference of multiple injection oil beams, increasing air utilization, promoting injection atomization, and being beneficial to the conversion between injection energy and turbulent kinetic energy, thus improving combustion. The tumble flow organized in the cylinder is broken up near the top dead center and converted into turbulent kinetic energy, which can effectively accelerate the combustion process, make the combustion in the cylinder more complete, and improve combustion efficiency.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

[0034] The embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of this application.

Claims

1. An opposed-piston two-stroke diesel engine vectored intake-space injection combustion system, comprising a cylinder liner, an intake piston, an exhaust piston, and a plurality of injectors, wherein the intake piston, the exhaust piston, and the inner wall of the cylinder liner cooperate to form a combustion chamber, characterized in that: The cylinder liner is provided with a plurality of vector air inlets and exhaust ports near the intake piston and the exhaust piston, respectively. The vector air inlets are composed of straight-flow ports and vortex ports, and the straight-flow ports and the vortex ports are arranged at intervals in the circumferential direction. There are two fuel injectors, which are staggered and arranged at the center plane of the cylinder liner to form a reverse vortex arrangement of the fuel injectors.

2. The system according to claim 1, wherein: In a cross section perpendicular to the piston movement direction, two side edges of the straight-flow air port form an included angle, and in a cross section along the piston movement direction, the straight-flow air port forms an elevation angle.

3. The system according to claim 1, wherein: The vortex air port is configured with an air intake inclination angle, wherein the air intake inclination angle in the direction of the air flow is greater than the air port inclination angle in the direction against the air flow.

4. The system according to claim 1, wherein: Taking the horizontal plane of the cylinder liner as a reference, the offset distances between the two injectors and the horizontal plane of the cylinder liner are equal.

5. The system according to claim 1, wherein: The fuel injector is provided with a plurality of spray holes, one of which is located on the central axis of the fuel injector, and the remaining spray holes form a spatial angle with the central axis of the fuel injector.

6. The system according to claim 1, wherein: The top surfaces of the intake piston and the exhaust piston are both in the shape of a shallow pit, and an oil injection notch is arranged at the piston fire land, and the oil injection notch is in a conical shape.

7. The system according to claim 6, characterized in that: The diameters of the intake piston and the exhaust piston are both in the range of 80 mm to 140 mm.

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