Symmetrical double-swirl combustion chamber suitable for opposed piston two-stroke engine

Abstract

The symmetrical double-swirl combustion chamber suitable for the opposed-piston two-stroke engine comprises pistons and a swirl combustion chamber, the swirl combustion chamber is formed by combining an upper portion combustion chamber and a lower portion combustion chamber and is integrally fan-shaped, and the wall face of the upper portion combustion chamber of the combustion chamber has a set curvature and is in smooth connection with an upper pit; the wall face of the lower combustion chamber is tangent to the pit of the upper combustion chamber and extends downwards to form an upper / lower combustion chamber boundary arc ridge, the pit of the combustion chamber is connected with an air inlet piston and an exhaust piston, and an oil sprayer is arranged near the center line of the combustion chamber. According to the symmetrical double-swirl combustion chamber suitable for the opposed-piston two-stroke engine, the problems that radial oil-gas mixing of the opposed-piston two-stroke engine is not uniform, and the thermal load difference between an air inlet piston and an exhaust piston is large are solved, the utilization rate of air in a cylinder is increased, the combustion efficiency is improved, and the thermal load of the pistons is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of internal combustion engine structure design, and in particular relates to a symmetrical double swirl combustion chamber suitable for an opposed-piston two-stroke engine. Background Art

[0002] The opposed piston two-stroke piston engine consists of two pistons driven by two crankshafts arranged opposite to each other to form a combustion chamber. The cylinder head, intake and exhaust valves and their drive systems are eliminated, and the air is exchanged in the form of air ports. This configuration engine has a compact structure, a lighter weight and smaller volume than the non-opposed layout, and less heat transfer loss in the combustion chamber; compared with the traditional four-stroke engine, the power is almost doubled. However, the injector is arranged between the intake and exhaust pistons, and the radial spray distribution is not conducive to fully utilizing the air in the combustion chamber. The uneven distribution of oil and gas leads to poor combustion effect and low combustion efficiency. Summary of the invention

[0003] In view of this, the present invention aims to propose a symmetrical double swirl combustion chamber suitable for an opposed-piston two-stroke engine, so as to enhance the oil-gas mixing capacity in the cylinder, improve the air utilization rate, and improve the combustion efficiency.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine comprises a piston and a swirl combustion chamber, wherein the swirl combustion chamber is formed by combining an upper combustion chamber and a lower combustion chamber and is fan-shaped as a whole, wherein the wall surface of the upper combustion chamber has a set curvature and is smoothly connected to an upper concave pit; the wall surface of the lower combustion chamber is tangent to the concave pit of the upper combustion chamber and extends downward to form an upper / lower combustion chamber boundary arc ridge, the combustion chamber concave pit is connected to an intake piston and an exhaust piston, and an injector is provided near the center line of the combustion chamber.

[0006] Furthermore, the swirl combustion chamber is a symmetrical double swirl combustion chamber and is constructed by a conical arc.

[0007] Furthermore, the method for constructing the symmetrical double-vortex combustion chamber is as follows: determining the basic dimensions of the combustion chamber profile section, including the combustion chamber vertex position L2, the combustion chamber bottom position L4, the position L3 of the upper / lower combustion chamber boundary arc ridge and the distance d from the arc ridge to the piston top plane, using a conical arc line to construct the upper / lower wall profile, with the main control parameters being the wall curvature and the pit angle; based on the determined combustion chamber cross-sectional profile, cutting the piston top surface at a set angle along a rotation axis parallel to the cylinder axis and passing through the apex or above the apex of the combustion chamber cross-sectional profile to form the basic profile of the fan-shaped vortex combustion chamber, with the main control parameters being L1 and γ; then the end faces on both sides are rotated and cut around the edge intersecting with the piston top plane to form the final double-vortex combustion chamber.

[0008] Furthermore, the wall angle of the upper combustion chamber is 0.5°, the curvature of the pit of the upper combustion chamber is α, and 70°≤α≤90°.

[0009] Furthermore, the wall angle of the lower combustion chamber is 0.5°, and the curvature of the pit of the lower combustion chamber is α, 95°≤β≤115°.

[0010] Furthermore, the distance between the axis of the rotating shaft and the axis of the cylinder is 2 mm ≤ L1 ≤ 6 mm.

[0011] Furthermore, the angular relationship of the combustion chamber cross section rotating along the rotation axis is 40°≤γ≤60°.

[0012] Compared with the prior art, the symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to the present invention has the following advantages:

[0013] (1) The symmetrical double swirl combustion chamber suitable for an opposed-piston two-stroke engine described in the present invention can, to a certain extent, solve the problems of uneven radial oil-gas mixing and large differences in thermal loads of the intake and exhaust pistons of the opposed-piston two-stroke engine. By forcibly inducing the spray on the wall to form a strong swirl motion, the mixing of fuel and air is promoted, the air utilization rate in the cylinder is improved, the combustion efficiency is improved, and the thermal load of the piston is reduced.

[0014] (2) The symmetrical double swirl combustion chamber suitable for an opposed-piston two-stroke engine described in the present invention has a simple method for determining the combustion chamber profile and fewer structural parameters, which is conducive to further optimization according to the injector characteristics and changes in engine operating conditions.

[0015] (3) The symmetrical double swirl combustion chamber suitable for an opposed-piston two-stroke engine described in the present invention has fuel injected into the combustion chamber along the radial direction of the cylinder. The fuel hits the arc ridge, and a portion of the combustion chamber is guided by the pit of the upper combustion chamber and develops along the wall surface toward the upper combustion chamber to form a swirl motion, thereby fully utilizing the air above the combustion chamber; a portion of the fuel hits the wall and rebounds toward the center of the combustion chamber, thereby making full use of the air in the center of the combustion chamber; the last portion of the fuel develops along the wall surface of the lower combustion chamber to the lower combustion chamber, and the spray on the intake and exhaust sides hits the center of the combustion chamber under the guidance of the pit of the lower combustion chamber, thereby forming a strong swirl motion, promoting oil-gas mixing, improving the air utilization rate in the cylinder, and achieving higher combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0017] Figure 1It is a schematic diagram of a combustion system of an opposed-piston two-stroke engine according to an embodiment of the present invention;

[0018] Figure 2 It is a cross-sectional view of the combustion chamber configuration according to an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of a combustion chamber construction process according to an embodiment of the present invention;

[0020] Figure 4 The simulation results of the combustion chamber example described in the embodiment of the present invention are as follows Figure 1 ;

[0021] Figure 5 The simulation results of the combustion chamber example described in the embodiment of the present invention are as follows Figure 2 ;

[0022] Figure 6 The simulation results of the combustion chamber example described in the embodiment of the present invention are as follows Figure 3 .

[0023] Description of reference numerals:

[0024] 1-intake piston; 2-exhaust piston; 3-upper combustion chamber; 4-lower combustion chamber; 5-upper / lower combustion chamber dividing arc ridge; 6-injector; 7-No. 1 rotating shaft; 8-No. 2 rotating shaft. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0028] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0029] A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine, such as Figures 1 to 6 As shown, it includes an intake piston 1, an exhaust piston 2, an upper combustion chamber 3, a lower combustion chamber 4, an upper / lower combustion chamber boundary arc ridge 5 and an injector 6, including a piston and a swirl combustion chamber, a symmetrical double swirl combustion chamber is formed by combining the upper combustion chamber 3 and the lower combustion chamber 4 and is fan-shaped as a whole, the wall of the upper combustion chamber 3 of the combustion chamber has a set curvature, and is smoothly connected to the upper pit; the wall of the lower combustion chamber 5 is tangent to the pit of the upper combustion chamber 3 and extends downward to form an upper / lower combustion chamber boundary arc ridge 5, the combustion chamber pit is connected to the intake piston 1 and the exhaust piston 2, and an injector 6 is provided near the center line when the intake piston 1 and the exhaust piston 2 are closest to each other.

[0030] The symmetrical double swirl combustion chamber is constructed through a conical arc, which further simplifies the structural characteristic parameters while ensuring the compression ratio and the wall-forced induced spray swirl effect, which is beneficial to the engine oil-gas chamber matching optimization research and improves efficiency.

[0031] The method for constructing a symmetrical double swirl combustion chamber is as follows: determine the basic dimensions of the combustion chamber profile section, including the combustion chamber vertex position L2, the combustion chamber bottom position L4, the position L3 of the upper / lower combustion chamber boundary arc ridge 5, and the distance d from the arc ridge to the piston top plane, and use a conical arc line to construct the upper / lower wall profile, and the main control parameters are the wall curvature and the pit angle. According to the determined combustion chamber cross-sectional profile, rotate along an axis parallel to the cylinder axis and passing through the apex or above the apex of the combustion chamber section (the first rotation axis 7 and the second rotation axis 8) to cut the piston top surface at a certain angle to form the basic profile of the fan-shaped swirl combustion chamber, and the main control parameters are L1 and γ; then the two side end faces are rotated and cut around the edge intersecting with the piston top plane to form the final double swirl combustion chamber, and the construction method of the intake and exhaust piston combustion chambers is the same.

[0032] The wall angle of the upper combustion chamber is 0.5°, and the curvature of the pit of the upper combustion chamber is α, 70°≤α≤90°.

[0033] The wall angle of the lower combustion chamber is 0.5°, and the curvature of the pit of the lower combustion chamber is α, 95°≤β≤115°.

[0034] The distance relationship between the axis of the rotating shaft and the axis of the cylinder is 2mm≤L1≤6mm.

[0035] The angular relationship of the combustion chamber cross section along the rotation axis is 40°≤γ≤60°.

[0036] Example 1

[0037] The present invention provides a symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine, with an example size of 52 mm piston diameter, a combustion chamber profile cross-sectional size of 0.5° upper combustion chamber wall angle, 80° upper combustion chamber pit curvature; 0.5° lower combustion chamber wall angle, 95° lower combustion chamber pit curvature; the distance between the arc ridge and the center of the intake and exhaust piston is 2.88 mm. The distance between the rotation axis and the combustion chamber vertex axis parallel to the cylinder axis is 5 mm, and the rotation angle is 45°.

[0038] like Figures 3 to 6 As shown, the fuel is sprayed into the combustion chamber along the radial direction of the cylinder, and the fuel hits the arc ridge. A part of the combustion chamber is guided by the pit of the upper combustion chamber, and develops along the wall surface toward the upper combustion chamber to form a vortex motion, thereby fully utilizing the air above the combustion chamber; a part of the fuel rebounds to the center of the combustion chamber after hitting the wall, which is conducive to fully utilizing the air in the center of the combustion chamber; the last part of the fuel develops along the wall surface of the lower combustion chamber to the lower combustion chamber, and the spray on the intake and exhaust sides hits the center of the combustion chamber under the guidance of the pit of the lower combustion chamber, forming a strong vortex motion, promoting oil-gas mixing, improving the utilization rate of air in the cylinder, and achieving higher combustion efficiency, with the combustion efficiency reaching 49.2%.

[0039] This solution can solve the problems of uneven radial oil-gas mixing and large difference in thermal load of intake and exhaust pistons in opposed-piston two-stroke engines. It can force the wall surface to induce spray to form a strong vortex motion, promote the mixing of fuel and air, improve the air utilization rate in the cylinder, improve the combustion efficiency, and reduce the thermal load of the piston.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine, characterized in that: It includes a piston and a swirl combustion chamber. The swirl combustion chamber is formed by combining an upper combustion chamber and a lower combustion chamber, and is fan-shaped as a whole. The wall of the upper combustion chamber has a set curvature and is smoothly connected to the upper pit; the wall of the lower combustion chamber is tangent to the pit of the upper combustion chamber and extends downward to form an upper / lower combustion chamber boundary arc ridge. The combustion chamber pit is connected to the intake piston and the exhaust piston, and an injector is provided near the center line of the combustion chamber.

2. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to claim 1, characterized in that: The swirl combustion chamber is a symmetrical double swirl combustion chamber and is constructed by a tapered arc.

3. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to claim 1, characterized in that: The method for constructing a symmetrical double swirl combustion chamber is as follows: determine the basic dimensions of the combustion chamber profile section, including the combustion chamber vertex position L2, the combustion chamber bottom position L4, the position L3 of the upper / lower combustion chamber boundary arc ridge and the distance d from the arc ridge to the piston top plane, use a conical arc line to construct the upper / lower wall profile, and the main control parameters are the wall curvature and the pit angle; according to the determined combustion chamber cross-sectional profile, cut the piston top surface at a set angle along a rotation axis parallel to the cylinder axis and passing through the apex or above the apex of the combustion chamber section to form the basic profile of the fan-shaped swirl combustion chamber, and the main control parameters are L1 and γ; then the end faces on both sides are rotated and cut around the edge intersecting with the piston top plane to form the final double swirl combustion chamber.

4. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to claim 1, characterized in that: The wall angle of the upper combustion chamber is 0.5°, and the curvature of the pit of the upper combustion chamber is α, 70°≤α≤90°.

5. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to claim 1, characterized in that: The wall angle of the lower combustion chamber is 0.5°, and the curvature of the pit of the lower combustion chamber is α, 95°≤β≤115°.

6. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to claim 2, characterized in that: The distance relationship between the axis of the rotating shaft and the axis of the cylinder is 2mm≤L1≤6mm.

7. A symmetrical double swirl combustion chamber suitable for an opposed piston two-stroke engine according to claim 2, characterized in that: The angular relationship of the combustion chamber cross section along the rotation axis is 40°≤γ≤60°.

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