Opposed piston internal combustion engine
Patent Information
- Application Number
- JP2024546018
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-02
- Filing Date
- 2023-01-27
- Publication Date
- 2026-02-03
AI Technical Summary
Existing opposing piston type internal combustion engines lack efficiency and cleanliness, particularly in two-stroke engines, due to incomplete combustion and exhaust gas leakage.
The engine design includes a phase shift between crankshafts, evenly distributed intake and exhaust ports, and a compression system with synchronized crankshaft transmission, allowing for precise gas discharge and turbocharged operation, using oil-free fuels and a frustocone-triangular piston head for enhanced fuel-air mixing.
This design achieves 100% exhaust gas discharge, cleaner emissions, and a temporary turbocharge effect, mimicking a two-stroke engine's efficiency with reduced leakage, while utilizing oil-free fuels.
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Abstract
Description
[Technical field]
[0001] The present invention relates to internal combustion engines, and more particularly to opposed piston internal combustion engines. [Background technology]
[0002] Description of the Prior Art An opposed piston internal combustion engine is described in US Patent Application Publication No. 2018128203. The opposed piston internal combustion engine described comprises three working cylinders, each of which has a first working piston and a second working piston. The three first working pistons are in turn connected to a first crankshaft via their rods, and the three second working pistons are connected to a second crankshaft via their rods. Both crankshafts are connected via a gear transmission. A similar structure, but with one working cylinder, is described in Canadian Patent Application Publication No. 2645325.
[0003] An opposed piston internal combustion engine further comprising a screw compressor for delivering compressed air to the working cylinder is described in US 2009 / 0151663 A1. A similar opposed piston internal combustion engine with a screw compressor is described in US 2015068492 A1. Another similarly designed two-stroke opposed piston engine is disclosed in GB 2030217 A1.
[0004] In view of the above-mentioned prior art, the objective is to create a more efficient opposed piston internal combustion engine. Summary of the Invention [Problem to be solved by the invention]
[0005] The object of the present invention can be achieved by providing an opposed piston internal combustion engine comprising a working cylinder with a first working piston and a second working piston, a first crankshaft and a second crankshaft, the first working piston being connected to the first crankshaft via a first working rod and the second working piston being connected to the second crankshaft via a second working rod. The engine comprises an intake port formed on the working cylinder in the stroke region of the second working piston and an exhaust port formed on the working cylinder in the stroke region of the first working piston. The engine also comprises an ignition plug located in a central portion of the working cylinder and a fuel injection nozzle also located in a central portion of the working cylinder.
[0006] The engine comprises at least three spark plugs evenly distributed around the circumference of the working cylinder. Additionally, the engine may comprise at least two fuel injection nozzles evenly distributed around the circumference of the working cylinder. In another embodiment of the invention, the engine may comprise two fuel injection nozzles or three fuel injection nozzles, but six spark plugs.
[0007] The intake port may consist of a number of intake ports evenly distributed around the circumference of the working cylinder, thereby providing an even and all-round air inflow, while the exhaust port may consist of a number of exhaust ports evenly distributed around the circumference of the working cylinder, thereby providing an even and all-round air outflow, furthermore the inflow may be via a non-return air inflow valve.
[0008] The engine includes a compression cylinder positioned adjacent to the working cylinder. A first compression piston and a second compression piston are disposed within the compression cylinder, where the compression piston heads face each other, similar to the working cylinder with the working piston. The first compression piston is connected to a first crankshaft via a first compression rod, and the second compression piston is connected to a second crankshaft via a second compression rod. Both working pistons and both compression pistons are disposed on the same crankshaft, respectively, providing a mechanical connection between the stroke of the working piston and the stroke of the compression piston that generates compressed air for the working cylinder. To provide fluid communication between the compression piston and the working piston in this manner, the engine includes an air exchange port formed in a central portion of the compression cylinder and configured to provide an inflow and outflow of air from the compression cylinder, and a compressed air overflow passage providing a fluid connection between the compression cylinder and the working cylinder, so that air compressed in the compression cylinder can move to the working cylinder through the intake port of the working cylinder. The air exchange port may consist of a plurality of air exchange ports evenly distributed around the circumference of the compression cylinder, thus providing an even and full circumferential flow of air in and out.
[0009] The synchronization of the first and second crankshafts is provided by a crankshaft transmission, which connects the first and second crankshafts, and can be a chain transmission, a belt transmission, including a gear belt transmission, or a gear transmission.
[0010] The present opposed piston internal combustion engine is characterized in that the phase shift of the first working rod of the first crankshaft, specifically the neck of said first working rod, from the phase of the second working rod of the second crankshaft, specifically the neck of said second working rod, is in the range of 15 to 75 degrees, preferably 40 to 50 degrees, more preferably 45 degrees. This shift ensures that the combustion gases that have completed their work are discharged from the combustion chamber of the cylinder before the ventilation process of the combustion chamber of the cylinder begins. The aforementioned phase shift makes it possible to generate a provisional turbocharging effect at the end of the ventilation cycle, which is obtained by closing the intake and exhaust ports at a certain operating point, taking advantage of the linear speed of the respective working pistons. Such a structure ensures that the combustion chamber discharges 100% of the exhaust gases.
[0011] The above-mentioned turbocharging effect can be observed at the moment when the working piston moves to bottom dead center (BDC) after ignition of the combustible mixture. The exhaust port is opened and most of the gas is expelled through it. The intake port is gradually opened and the overpressure generated by the compression creates a draft effect, and the combustion chamber of the working cylinder is completely expelled of combustible gases. The exhaust port closes, but the intake port is still slightly open, and the final blow generated by the compression, which can be temporarily recognized as a super-intake gas, flows into the working cylinder through its intake port.
[0012] Furthermore, the phase shift of the compression rod of the second crankshaft from the phase of the second working rod of the same second crankshaft is in the range of 80 to 150 degrees, preferably 105 to 115 degrees, more preferably 107 to 110 degrees.
[0013] The engine design described above allows for the utilization of oil-free fuels, thereby resulting in cleaner exhaust gases, compared to other two-stroke engines.
[0014] The first working piston, the cylinder, and the second working piston define a combustion chamber. The head of each working piston has, in its cross section, the shape of a truncated cone with concave sides - a triangular shape. Here, the head of each working piston is formed with recesses extending radially from the central part of the head to the sides of the head as flow deflectors. The radially extending recesses are oriented to connect to the intake and exhaust ports during their respective movements.
[0015] The triangular shape of the working piston head allows a toroidal working chamber to be formed when the working piston is at top dead center (TDC). This allows, for example, two fuel injection nozzles to deliver an optimal amount of fuel directly into the toroidal space of the working chamber at the end of the compression cycle. Furthermore, the fuel injection nozzles can be positioned offset from the cylinder central axis, so that the fuel is injected in the working chamber below the periphery, enhancing the mixing of the fuel and air.
[0016] The exhaust system includes a resonator and a muffler. A catalyst may also be optionally used.
[0017] The engine can be considered a two-stroke engine and therefore has a litre capacity and inherent combustion chamber leak tightness characteristic of a two-stroke engine. [Brief description of the drawings]
[0018] List of drawings The drawings illustrate, by way of example, various embodiments of the invention falling within the scope of protection of the invention as claimed. [Figure 1] Figure 1 shows an opposed piston internal combustion engine with cutaways for visibility, allowing the engine assembly and its components to be clearly seen. Figure 1 shows the condition when both working pistons (10, 20) are at bottom dead centre (BDC). [Diagram 2]FIG. 2 shows the same engine as FIG. 1, but with both working pistons (10, 20) already in a position in their travel from BDC towards top dead centre (TDC). [Diagram 3] FIG. 3 shows the same engine as in FIGS. 1 and 2, but with both working pistons (10, 20) already at TDC and in a position defining the compression space. [Figure 4] FIG. 4 shows the same engine as FIGS. 1 to 3, but with both working pistons (10, 20) in a position moving from TDC to BDC, causing the gas present in cylinder (1) to expand. [Diagram 5] 5 shows the operation scheme of an opposed piston internal combustion engine when the second working piston (20) is at BDC and its second working rod (23) is at 0 degrees position. At the same time, the first working rod (13) of the first working piston (10) has a phase shift (X) of 45 degrees with respect to the second working piston (20). [Figure 6] FIG. 6 shows the operating scheme of the engine already shown in FIG. 5, when the second working rod (23) of the second working piston (20) has moved through 45°. [Figure 7] FIG. 7 shows the operating scheme of the engine already shown in FIGS. 5 and 6, when the second working rod (23) of the second working piston (20) has traveled 90°. [Figure 8] FIG. 8 shows the operating scheme of the engine already shown in FIGS. 5 to 7, when the second working rod (23) of the second working piston (20) has traveled 135°. [Figure 9] FIG. 9 shows the operating scheme of the engine already shown in FIGS. 5 to 8, when the second working rod (23) of the second working piston (20) has traveled 180°. [Figure 10] FIG. 10 shows the operating scheme of the engine already shown in FIGS. 5 to 9, when the second working rod (23) of the second working piston (20) has traveled 225°. [Figure 11] FIG. 11 shows the operating scheme of the engine already shown in FIGS. 5 to 10 when the second working rod (23) of the second working piston (20) has traveled 270°. [Figure 12] FIG. 12 shows the operating scheme of the engine already shown in FIGS. 5 to 11 when the second working rod (23) of the second working piston (20) has traveled 315°. [Figure 13] FIG. 13 shows the operating scheme of the engine already shown in FIGS. 5 to 12, when the second working rod (23) of the second working piston (20) has moved 360 degrees or, as shown in FIG. 5, has returned to its initial position, which is 0 degrees. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Detailed Description of Examples of Implementations of the Invention To illustrate the objects, advantages and capabilities of the present invention, examples of implementations of the present invention have been described with reference to the drawings.
[0020] 1 to 4 show an opposed piston type internal combustion engine comprising a working cylinder (1), a first working piston (10) and a second working piston (20), in which the heads (11, 21) of both working pistons (10, 20) face each other. The heads (11, 21) of each working piston (10, 20) have, in cross section, the shape of a truncated cone with slightly concave sides. Furthermore, in the heads (11, 21) of each working piston, recesses (14, 24) are formed which extend radially from the central part of the heads (11, 21) to the sides of the heads (11, 21). The engine comprises a first crankshaft (12) and a second crankshaft (22). The first working piston (10) is connected to the first crankshaft (12) via the first working rod (13), and the second working piston (20) is connected to the second crankshaft (22) via the second working rod (23). Furthermore, the phase shift (X) of the first working rod (13) of the first crankshaft (12) from the phase of the second working rod (23) of the second crankshaft (22) is 45 degrees, as can be seen in particular in FIG. 5. The engine also comprises an intake port (25) formed on the working cylinder (1) in the stroke region of the second working piston (20) and an exhaust port (15) formed on the working cylinder (1) in the stroke region of the first working piston (10). The number of intake ports (25) and exhaust ports (15) corresponds to the number of recesses (14, 24) in the heads (11, 21) of the pistons. The engine also comprises a spark plug (50) arranged in a central portion of the working chamber of the working cylinder (1) and a fuel injection nozzle (51) arranged in a central portion of the working cylinder (1). The arrangement positions of the spark plug (50) and the fuel injection nozzle (51) are shown diagrammatically in Figures 1 to 4. The engine may comprise three or even six spark plugs (50) and two or three fuel injection nozzles (51) in its different versions. The engine further comprises a compression cylinder (2) arranged adjacent to the working cylinder (1) and a first compression piston (30) and a second compression piston (40), in which the heads (31, 41) of the compression pistons (30, 40) face each other.The first compression piston (30) is connected to the first crankshaft (12) via the first compression rod (33), and the second compression piston (40) is connected to the second crankshaft (22) via the second compression rod (43). The phase shift (Y) of the second compression rod (43) of the second crankshaft (22) from the phase of the second working rod (23) of the second crankshaft (22) is then 108.4 degrees, as can be seen in particular in FIG. 5. In the central portion of the compression cylinder (2) there is an air exchange port (34) configured to provide an inflow and outflow of air from the compression cylinder (2). The engine comprises a crankshaft transmission (3) connecting the first crankshaft (12) and the second crankshaft (22).
[0021] The engine further includes a compressed air overflow passage (52) that provides fluid communication between the compression cylinder (2) and the working cylinder (1) so that air compressed in the compression cylinder (2) can pass to the working cylinder (1) through its intake port (25). The location of the air overflow passage (52) is shown diagrammatically in Figures 5 to 13. Although the air overflow passage (52) is necessary for the engine, it is not shown in Figures 1 to 4 to avoid overcrowding the respective figures.
[0022] Figure 5 shows the working scheme of the opposed piston internal combustion engine when the second working piston (20) is at BDC and the position of its second working rod (23) on the second crankshaft (22) is 0 degrees. At the same time, the position of the first working rod (13) of the first working piston (10) on the first crankshaft (12) has a phase shift (X) of 45 degrees with respect to the position of the second working piston (20) on the second crankshaft (22). In this state, the air sent from the compression piston (2) is sent to the working piston (1) through the intake port (25), and the previously burned exhaust gas is discharged through the exhaust port (15). In this state, the intake port (25) is fully open. The exhaust port (15) is partially open. The compression pistons (30, 40) in the compression cylinder (2) continue to move towards each other, forcing compressed air through the air exchange port (34) into the compressed air overflow passage (52) and into the working cylinder (1).
[0023] Figure 6 shows the operating scheme of the engine already illustrated in figure 5 when the second working rod (23) of the second working piston (20) moves or when the second crankshaft (22) rotates by 45 degrees. Both working pistons (10, 20) continue to move towards each other. The exhaust port (15) is already closed. However, the intake port (15) is gradually closed or covered by displacing the second working piston (20) in the direction towards the first working piston (10). Compression of the air present in the working cylinder (1) starts. The compression pistons (30, 40) have almost reached their TDC, by which time the crankshaft has rotated about 20 degrees. The air still being pumped is also directed towards the working cylinder (1).
[0024] Figure 7 shows the operation scheme of the engine illustrated in Figures 5 and 6 when the second working rod (23) of the second working piston (20) moves or the second crankshaft (22) rotates 90 degrees. Both working pistons (10, 20) continue to move towards each other. The exhaust port (15) and the intake port (25) are closed. The compression pistons (30, 40) have already reached TDC, have passed TDC and moved to their BDC with about 20 degrees of crankshaft rotation. The air exchange port (34) is open to allow the intake of the next part of the air in the compression cylinder (2).
[0025] Figure 8 shows the operating scheme of the engine already illustrated in figures 5 to 7 when the second working rod (23) of the second working piston (20) moves or the second crankshaft (22) rotates 135 degrees. Both working pistons (10, 20) are closest to each other. The first working piston (10) has reached TDC. A toroidal combustion chamber (50) is formed between the curved surfaces of the pistons (10, 20). Fuel is injected. The compression piston (30, 40) takes in a part of the new air through the air exchange port (34) and the non-return air valve (35).
[0026] FIG. 9 shows the operating scheme of the engine already illustrated in FIGS. 5 to 8 when the second working rod (23) of the second working piston (20) moves or the second crankshaft (22) rotates 180 degrees. Both working pistons (10, 20) are still closest to each other. The toroidal combustion chamber (50) is still formed between the curved surfaces of the pistons (10, 20). The second working piston (20) has reached TDC. The first working piston (10) has already moved to BDC. At this stage, the combustion of the combustible mixture also takes place in the toroidal combustion chamber (50). The compression pistons (30, 40) still suck in a part of the new air through the air exchange ports (34).
[0027] Figure 10 shows the operating scheme of the engine already illustrated in figures 5 to 9 when the second working rod (23) of the second working piston (20) moves or when the second crankshaft (22) rotates 225 degrees. Both working pistons (10, 20) move away from each other in the direction towards BDC. A working stroke occurs. The compression pistons (30, 40) still take in a part of new air through the air exchange port (34).
[0028] Figure 11 shows the operating scheme of the engine already illustrated in Figures 5 to 10, when the second working rod (23) of the second working piston (20) moves or the second crankshaft (22) rotates 270 degrees. The first working piston (10) has already reached its position when it opens the exhaust port (15), and the burnt gases can be discharged from the working cylinder (1). The intake port (25) is still closed / begins to be gradually closed. No further air inflow into the compression cylinder (2) occurs anymore, and the air already present in the compression cylinder (2) is introduced into the working cylinder (1) to fill it with a part of new air and to discharge the burnt gases.
[0029] Figure 12 shows the operating scheme of the engine already illustrated in Figures 5 to 11 when the second working rod (23) of the second working piston (20) moves or the second crankshaft (22) rotates 315 degrees. The first working piston (10) has reached BDC. The exhaust ports (15) are fully open. The intake ports (25) are partially open and the air pushed out from the compression cylinder (2) flows in through them. The flowing in air also facilitates the removal of the burnt gases through the exhaust ports (15).
[0030] Figure 13 shows the working scheme of the engine already illustrated in Figures 5 to 12 when the second working rod (23) of the second working piston (20) moves or the second crankshaft (22) rotates 360 degrees or returns to its initial position, which is 0 degrees as shown in Figure 5. Air coming from the compression cylinder (2) is still pushed into the working cylinder (1) and the combustion gases are still expelled. And the whole two-stroke cycle is restarted from the beginning as before.
[0031] It should be understood that the object of the present invention may be subject to various modifications and alternative forms, as several embodiments of the object of the present invention are shown in the drawings, but the invention is not intended to be limited to the embodiments specifically described herein, but rather includes all modifications, equivalents, and alternatives that fall within the scope of protection of the object of the present invention as defined in the claims.
Claims
1. An opposed piston internal combustion engine, an actuating cylinder (1); a first working piston (10) and a second working piston (20), the heads (11, 21) of the first working piston (10) and the second working piston (20) being opposed to each other; a first crankshaft (12) and a second crankshaft (22), wherein the first working piston (10) is connected to the first crankshaft (12) via a first working rod (13), and the second working piston (20) is connected to the second crankshaft (22) via a second working rod (23), wherein a phase shift (X) of the first working rod (13) of the first crankshaft (12) from the phase of the second working rod (23) of the second crankshaft (22) is in the range of 15 to 75 degrees, preferably 40 to 50 degrees, and more preferably 45 degrees; an intake port (25) formed above the working cylinder (1) in the stroke region of the second working piston (20); an exhaust port (15) formed on the working cylinder (1) in the stroke region of the first working piston (10); a spark plug (50) disposed in the central portion of the working chamber of the working cylinder (1); a fuel injection nozzle (51) disposed in the central portion of the working cylinder (1); a compression cylinder (2) positioned adjacent to the working cylinder (1); a first compression piston (30) and a second compression piston (40), the heads (31, 41) of both compression pistons (30, 40) facing each other, the first compression piston (30) being connected to the first crankshaft (12) via a first compression rod (33), and the second compression piston (40) being connected to the second crankshaft (22) via a second compression rod (43), wherein a phase shift (Y) of the second compression rod (43) of the second crankshaft (22) from a phase of the second operating rod (23) of the second crankshaft (22) is in the range of 80 to 150 degrees, preferably 105 to 115 degrees, more preferably 107 to 110 degrees; an air exchange port (34) formed in a central portion of the compression cylinder (2) and configured to allow air to flow in and out of the compression cylinder (2); a compressed air overflow passage (52) that provides a fluid connection between the compression cylinder (2) and the working cylinder (1) so that air compressed in the compression cylinder (2) can move to the working cylinder (1) through the intake port (25); a crankshaft transmission (3) connecting the first crankshaft (12) and the second crankshaft (22), characterized in that the head (11, 21) of each working piston (10, 20) has a truncated cone shape in cross section, and the head (11, 21) of each working piston (10, 20) is formed with a recess (14, 24) extending radially from a central portion of the head (11, 21) to a side portion of the head (11, 21); An opposed piston internal combustion engine comprising:
2. 2. The opposed-piston internal combustion engine of claim 1, wherein said truncated cone has a concave side.
3. 2. Opposed piston internal combustion engine according to claim 1, characterized in that the working volume of the compression cylinder (2) is 10 to 50%, preferably 20 to 30%, greater than the working volume of the working cylinder (1).
4. 2. The opposed-piston internal combustion engine of claim 1, wherein the opposed-piston internal combustion engine comprises at least three spark plugs (50).
5. 2. An opposed-piston internal combustion engine according to claim 1, characterized in that the opposed-piston internal combustion engine comprises at least two fuel injection nozzles (51).