Opposed two-stroke combustion system capable of accelerating diffusion of spatter

Abstract

The opposed two-stroke combustion system comprises pistons, the two pistons are symmetrically installed in an opposed piston engine, and an oil sprayer is installed on an engine body. When the distance between the two pistons is closest, the nozzle residual seam is approximately combined into a round hole which can contain and does not make contact with the oil sprayer nozzle. According to the opposed two-stroke combustion system capable of accelerating diffusion of the splashes, fog injectors collide with the splashing wall face in advance, large liquid drops are converted into small liquid drops in advance, the fog injection development time is saved, the combustion duration is shortened, the requirement of two-stroke work is better met, fuel oil can be prevented from being attached to the wall through the arrangement of gas film steps, and the service life of the fuel oil is prolonged. The economical efficiency and the practicability of the engine are improved; meanwhile, larger oil injection pressure can be introduced in the fog injection impact process, the larger the oil injection pressure is, the better the effect that liquid drops are broken into small liquid drops in the impact process is, the more ideal the angle of liquid drop reflection is, the opposed piston technology is not affected by the limitation of the oil injection pressure any more, and therefore the limit of the opposed piston technology is expanded.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of opposed-piston two-stroke engines, and particularly relates to a splash-accelerated diffusion opposed two-stroke combustion system. BACKGROUND

[0002] Opposed-piston two-stroke engines are widely studied due to high power density, and the oil injector is installed on the side wall due to the design of the opposed pistons. The unit cycle duration of the two-stroke is short, if the mist injection is sprayed out by the oil injector at a small included angle, the mists are fused with each other to make the droplets large and difficult to evaporate, and the combustion duration is increased to not meet the working requirements of the two-stroke; if the mist injection is sprayed out at a large included angle, serious fuel wall adhesion phenomenon occurs, and the combustion duration is also increased. And no matter the mists are at a small included angle or a large included angle, the injection pressure cannot be too large, because the fuel wall adhesion phenomenon will be aggravated. The principle of spray diffusion is that the mist injection rubs against the air at high speed to convert the energy input by the injection pressure into the energy of droplet separation, and then promote the spatial distribution of the droplets, which indicates that the time of diffusion and evaporation completion depends on the time of complete mist injection, and the whole time is later. It is hoped that the energy carried by the injection pressure can be converted into the energy of droplet separation by the way of early collision of the mist injection with the splash wall, so as to promote the diffusion and evaporation of the mist injection. SUMMARY

[0003] The present application provides a splash-accelerated diffusion opposed two-stroke combustion system, which solves the problem that the traditional oil injector and the spray process cannot meet the rapid combustion requirements of the opposed two-stroke engine, and at the same time introduces higher injection pressure to expand the limit of the technology.

[0004] In order to solve the above technical problems, the present application provides a splash-accelerated diffusion opposed two-stroke combustion system, which comprises two pistons (1) arranged symmetrically and an oil injector (2) installed on the engine body, and is characterized by: Half-circular nozzle excess joints (111) are arranged on the piston faces (11) of the two pistons (1), respectively, when the two pistons (1) move to the closest position, the two nozzle excess joints (111) jointly form a circular through hole for accommodating the nozzle (22) of the oil injector (2) without contacting the nozzle (22); A combustion chamber (113) is further arranged on the piston face (11), the combustion chamber (113) comprises a splash face (1131) and a diffusion face (1132) connected in sequence, the splash face (1131) is connected with the nozzle excess joint (111), and the cross-sectional profile of the splash face (1131) is parabolic, and the cross-sectional profile of the diffusion face (1132) is drop-shaped; A gas film step (1133) is arranged at the joint of the splash face (1131) and the diffusion face (1132), and the gas film step (1133) is configured such that the diameter of the splash face (1131) is smaller than the diameter of the diffusion face (1132).

[0005] Further, the diameter of the nozzle (22) of the fuel injector (2) is smaller than the diameter of the circular through hole formed by the nozzle clearance (111).

[0006] Further, the installation position of the fuel injector (2) is configured such that the intersection of the fuel spray emitted thereby is located at the focal point of the splash face (1131).

[0007] Further, the piston face (11) further comprises a flow extrusion face (112), which is a region of the piston crown face other than the combustion chamber (113) and the nozzle clearance (111), and is a planar structure as a whole.

[0008] Further, the gas film step (1133) is configured to guide the gas flow to form a gas film near the wall of the diffusion face (1132) during relative movement of the piston, for preventing fuel from adhering to the wall.

[0009] Further, the parabolic profile of the splash face (1131) is configured to guide the injected fuel to be reflected after impact, forming a predetermined spray trajectory (21) to facilitate fuel breaking and diffusion.

[0010] Further, the combustion chamber (113) takes a diameter of the piston face (11) as a symmetry axis (114), and the nozzle clearance (111), the splash face (1131) and the diffusion face (1132) are symmetrically arranged about the symmetry axis (114).

[0011] Further, the system is configured to allow the fuel injection pressure to be not less than 200 MPa, and to achieve secondary atomization of the fuel by the impact of the splash face (1131).

[0012] Further, the nozzle clearance (111) is provided with a semicircular through hole at the edge of the piston (1) with the symmetry axis (114) as the axis.

[0013] A two-stroke opposed piston engine, characterized in that it comprises the splash-accelerated diffusion two-stroke combustion system. Advantages

[0014] (1) The splash acceleration diffusion opposed two-stroke combustion system makes the spray injection collide with the splash wall surface in advance, converts large droplets into small droplets in advance, saves the development time of the spray injection, reduces the combustion duration, is more suitable for the needs of two-stroke operation, and the setting of the gas film step can avoid the occurrence of fuel wall adhesion, and improves the economy and practicability of the engine. (2) The splash acceleration diffusion opposed two-stroke combustion system makes the spray injection collision process can introduce greater injection pressure, the greater the injection pressure, the better the effect of breaking small droplets in the collision, the more ideal the angle of droplet reflection, so that the opposed piston technology is no longer affected by the limitation of injection pressure, thereby expanding the limit of the technology. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a schematic diagram of the piston structure of the splash acceleration diffusion opposed two-stroke combustion system according to the present application; Figure 2 FIG. 2 is a sectional view of the piston structure of the splash acceleration diffusion opposed two-stroke combustion system according to the present application; Figure 3 FIG. 3 is a schematic diagram of the fuel injector structure of the splash acceleration diffusion opposed two-stroke combustion system according to the present application; Figure 4 FIG. 4 is a schematic diagram of the overall structure of the splash acceleration diffusion opposed two-stroke combustion system according to the present application; Figure 5 FIG. 5 is a sectional view of the overall structure of the splash acceleration diffusion opposed two-stroke combustion system according to the present application; Figure 6 FIG. 6 is a schematic diagram of the spray trajectory of the splash acceleration diffusion opposed two-stroke combustion system according to the present application; BRIEF DESCRIPTION OF DRAWINGS 1-piston; 11-piston surface; 111-nozzle gap; 112-flow extrusion surface; 113-combustion chamber; 114-symmetry axis; 1131-splash surface; 1132-diffusion surface; 1133-gas film step; 2-fuel injector; 21-spray trajectory; 22-nozzle. DETAILED DESCRIPTION

[0016] In order to make the purpose, content and advantages of the present application clearer, the specific embodiments of the present application are described in further detail below.

[0017] As Figure 4 and Figure 5As shown in the drawings, the present application proposes a splash acceleration diffusion opposed two-stroke combustion system, which comprises a piston, two pistons 1 are symmetrically installed in an opposed piston engine, and an oil injector 2 is installed on the engine body. When the two pistons 1 are closest, the nozzle residual gap 111 is approximately combined into a circular hole, which can accommodate and not contact the oil injector nozzle 22.

[0018] As shown in the drawings, Figure 1 The piston 1 is in the shape of a cylinder as a whole, and the top surface is a piston surface 11. The piston surface 11 comprises a squish surface 112, a combustion chamber 113, and a nozzle residual gap 111 connected with the combustion chamber 113. A diameter of the piston surface 11 is an axis of symmetry 114.

[0019] The squish surface 112 is the piston surface excluding the combustion chamber 113 and the nozzle residual gap 111, and is in the shape of a plane as a whole. The nozzle residual gap 111 is a through hole in the shape of a semicircle and is arranged at the edge of the piston 1 with the axis of symmetry 114 as the axis.

[0020] As shown in the drawings, Figure 2 The combustion chamber 113 is composed of two parts, a splash surface 1131 and a diffusion surface 1132. The cross-sectional profile of the splash surface 1131 is in the shape of a parabola with the axis of symmetry 114 as the axis, and the cross-sectional profile of the diffusion surface 1132 is in the shape of a water drop. One end of the splash surface 1131 is connected with the nozzle residual gap 111, and the other end is connected with the diffusion surface 1132. At the connection between the splash surface 1131 and the diffusion surface 1132, the circular diameter of the splash surface 1131 is smaller than that of the diffusion surface 1132, that is, a gas film step 1133 is arranged.

[0021] As shown in the drawings, Figure 3 The oil injector 2 is a product, and the nozzle 22 thereof is in the shape of a cylinder. The diameter of the nozzle 22 is smaller than that of the nozzle residual gap 111. The oil injector 2 can spray a fuel jet at high pressure.

[0022] The opposed piston two-stroke engine is widely studied due to high power density. Due to the design of the opposed piston, the oil injector is installed on the side wall. The unit cycle duration of the two-stroke is short. If the oil injector sprays the mist injection at a small angle, the mist injections are fused with each other, the droplets are large and difficult to evaporate, the combustion duration is increased and cannot meet the working requirements of the two-stroke. If the mist injection is sprayed at a large angle, serious fuel wall adhesion phenomenon occurs. No matter whether the mist injections are at a small angle or a large angle, the injection pressure cannot be too large, because the fuel wall adhesion phenomenon will be aggravated, and the combustion duration will also be increased. The principle of spray diffusion is that the mist injection rubs against the air at high speed, converts the energy input by the injection pressure into the energy of droplet separation, and then promotes the spatial distribution of the droplets. It is shown that the time of diffusion and evaporation completion depends on the time of complete mist injection, which is overall later in time. It is hoped that the energy carried by the injection pressure can be converted into the energy of droplet separation by the way that the mist injection collides with the splash wall in advance, so as to promote the diffusion and evaporation of the mist injection.

[0023] On the one hand, the atomized jet impacts the splash wall in advance, transforming large droplets into smaller ones, saving time for atomized jet development, reducing combustion duration, and better meeting the needs of two-stroke operation. Furthermore, the design of the film vapor barrier can prevent fuel from adhering to the wall. On the other hand, the atomized jet impact process can introduce greater injection pressure. The greater the injection pressure, the better the effect of droplet breakup into smaller droplets during impact, and the more ideal the droplet reflection angle, thus freeing the opposed piston technology from the limitations of injection pressure.

[0024] like Figure 6 As shown, the cross-sectional profile of the splash surface is parabolic. When the fuel injector is installed so that the intersection of the fuel jets is at the focal point of the splash surface, the high-pressure fuel will rapidly impact the splash surface, break up, and bounce, forming the spray trajectory shown in Figure 21. This trajectory is ideal because some fuel has a low velocity and will move towards the diffuser along the tangential direction of the splash surface; at the same time, because the fuel jet itself has width, there will also be fuel diffusion between the two parallel trajectories. Therefore, a film gas step is set. When the two pistons move relative to each other, the opposing extrusion surfaces will force the airflow into the combustion chamber. Due to the presence of the film gas step, the airflow forced into the combustion chamber forms a film gas near the diffuser wall. Even if fuel moves tangentially along the splash surface to the vicinity of the diffuser wall, it will be cushioned by the film gas, preventing fuel from adhering to the wall.

[0025] In reality, the formation of a teardrop-shaped curve comes from the balance between gravity and liquid surface tension. During the spraying process, there is also a balance between the high-speed moving mist and the air film pressure, which makes the mist diffusion tend to form a teardrop shape. Therefore, setting the cross-sectional profile of the diffusion surface to a teardrop shape allows the mist to make full use of the air in the combustion chamber for combustion, thereby improving space utilization.

[0026] This invention enables the atomizer to impact the splash wall earlier, transforming large droplets into smaller ones in advance. This eliminates the time required for atomizer development, reduces the combustion duration, and better suits the needs of two-stroke engines. Furthermore, the design of the film vapor barrier prevents fuel from adhering to the wall, improving engine economy and practicality. Simultaneously, the atomizer impact process allows for the introduction of higher injection pressure. Higher injection pressure results in better droplet breakup during impact and a more ideal droplet reflection angle. This removes the limitations imposed by injection pressure on opposed piston technology, thus expanding the limits of this technology.

[0027] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A splash accelerated diffusion opposed two-stroke combustion system, comprising two pistons (1) arranged symmetrically and an injector (2) mounted on an engine block, characterized in that: a semicircular nozzle clearance (111) is arranged on a piston face (11) of each of the two pistons (1), and when the two pistons (1) move to the closest position, the two nozzle clearances (111) together form a circular through hole for accommodating a nozzle (22) of the injector (2) without contacting the nozzle (22); a combustion chamber (113) is further arranged on the piston face (11), the combustion chamber (113) comprises a splash face (1131) and a diffusion face (1132) connected in sequence, the splash face (1131) is connected with the nozzle clearance (111) and has a parabolic cross-sectional profile, and the diffusion face (1132) has a water-drop-shaped cross-sectional profile; a gas film step (1133) is arranged at a connection between the splash face (1131) and the diffusion face (1132), and the gas film step (1133) is configured such that a diameter of the splash face (1131) is smaller than a diameter of the diffusion face (1132).

2. The combustion system of claim 1, wherein: A diameter of the nozzle (22) of the injector (2) is smaller than a diameter of the circular through hole formed by the nozzle clearance (111).

3. The combustion system of claim 2, wherein: The injector (2) is mounted at a position such that an intersection of fuel oil beams sprayed by the injector (2) is located at a focal point of the splash face (1131).

4. The combustion system of claim 1, wherein: The piston face (11) further comprises a squish face (112), the squish face (112) is a piston top face region other than the combustion chamber (113) and the nozzle clearance (111) and has a planar structure as a whole.

5. The combustion system of claim 1, wherein: The gas film step (1133) is configured to guide gas flow to form a gas film near a wall of the diffusion face (1132) during relative movement of the pistons, so as to prevent fuel oil from adhering to the wall.

6. The combustion system of claim 1, wherein: The parabolic profile of the splash face (1131) is configured to guide the sprayed fuel oil to be reflected after impact, so as to form a predetermined spray trajectory (21) to facilitate breaking and diffusion of the fuel oil.

7. The combustion system of claim 1, wherein: The combustion chamber (113) takes a diameter of the piston face (11) as a symmetry axis (114), and the nozzle clearance (111), the splash face (1131) and the diffusion face (1132) are symmetrically arranged about the symmetry axis (114).

8. The combustion system of claim 1, wherein: The system is configured to allow an injection pressure of no less than 200 MPa, and to realize secondary atomization of fuel oil by using an impact effect of the splash face (1131).

9. The combustion system of claim 7, wherein: The nozzle clearance (111) is provided with a semicircular through hole at an edge of the piston (1) with the symmetry axis (114) as an axis.

10. An opposed-piston two-stroke engine, characterized by An engine comprising the splash accelerated diffusion opposed two-stroke combustion system according to any one of claims 1 to 9.

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