Four-stroke engine with a two-stage exhaust cycle

Abstract

The engine of the present invention includes a cylinder (8) having a peripheral wall defining a combustion chamber (3), a crankshaft, and a piston (4) movable within the cylinder (8). The intake valve and the exhaust valve (1, 2) respectively regulate the flow of air into the combustion chamber (3) or the flow of combustion products from the combustion chamber (3). The exhaust outlet port (9) has an opening in the peripheral wall at a position between the lowest position and the uppermost position of the piston, and the outlet port valve (10) is associated with the exhaust outlet port (9). During the exhaust stroke, there is a first exhaust stage in which the combustion products are discharged from the exhaust outlet port (9) when the upper surface of the piston (4) is below the opening and the outlet port valve (10) is open. In the second exhaust stage, while the piston (4) continues to move beyond the opening in the peripheral wall, the outlet port valve (9) closes and the combustion products remaining in the combustion chamber (3) are discharged from around the exhaust valve (2).

Description

Technical Field

[0001] The present invention relates to a four-stroke engine having a modified exhaust cycle, namely a two-stage exhaust cycle, a method of modifying an engine to include a two-stage exhaust cycle, and a cylinder for an engine that enables a two-stage exhaust cycle.

Background Art

[0002] A four-stroke engine has an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. In the intake stroke, the piston descends within the surrounding cylinder, drawing air into the cylinder through the intake valve, while at the same time the fuel injector injects fuel (or a fuel-air mixture) into the cylinder. In the subsequent compression stroke, the intake valve is closed, the crankshaft to which the piston is attached rotates, causing the piston to rise within the cylinder and compress the air / fuel mixture. In the subsequent combustion stroke, i.e., the power stroke, when the piston reaches the top of the cylinder, the spark plug or other ignition means ignites the air / fuel mixture. As a result of the resulting combustion, the piston is again pushed down to the bottom of the cylinder. In the subsequent exhaust stroke, when the piston reaches the bottom of the cylinder, the exhaust valve opens, and as the piston rises again, the exhaust gas is pushed out of the cylinder. At the same time, a large backpressure is generated on the piston, reducing the positive force that rotates the crankshaft. This cycle is repeated, and the crankshaft rotates to generate, for example, electrical power for driving a vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] An object of at least one embodiment of the present invention is to provide a new and improved four-stroke engine and an exhaust cycle that is more efficient than the conventional exhaust cycle of a four-stroke engine.

[0005] An object of at least one embodiment of the present invention is to provide a two-stage exhaust cycle for a four-stroke engine, whereby the four-stroke engine is more efficient than the exhaust cycle for a conventional four-stroke engine, the back pressure on the piston and the exhaust gas is significantly reduced, and thus it becomes a kind of five-stroke engine with improved engine efficiency. An object of at least one embodiment of the present invention is to provide a method for modifying or changing an existing engine to have a two-stage or dual-stage exhaust stroke.

[0006] To achieve one or more of these objects, and optionally other objects, the engine of the present invention includes a cylinder having a peripheral wall defining a combustion chamber; a crankshaft; and a piston movable within the cylinder toward a first upper side of the cylinder during a compression stroke and an exhaust stroke, and toward a second lower side of the cylinder during an intake stroke in which air is inhaled into the combustion chamber and a power stroke in which a mixture of air and fuel in the combustion chamber is ignited and the crankshaft to which the piston is connected rotates as a result of combustion of the air / fuel mixture. An intake valve is associated with the cylinder and regulates the flow of air into the combustion chamber during the intake stroke, while an exhaust valve is associated with the cylinder and regulates the flow of combustion products out of the combustion chamber. By being associated with the cylinder, the intake valve and the exhaust valve operate to move between a state or position that does not permit flow into or out of the combustion chamber and a state or position that permits flow into or out of the combustion chamber. These valves are disposed within a conduit communicating with the combustion chamber or have a portion that contacts an edge of the cylinder and moves away from this edge to open and close a channel to the combustion chamber.

[0007] The engine also includes an exhaust outlet port having an opening in the circumferential wall of the cylinder between the bottom and top of the piston, and an outlet port valve associated with the exhaust outlet port, i.e., it operates to move between a state or position that allows flow from the combustion chamber but does not allow backflow from the exhaust outlet port, and a state in which all flow between the combustion chamber and the exhaust outlet port is blocked.

[0008] In this configuration, the exhaust stroke is a two-stage exhaust stroke. In the first exhaust stage, the upper surface of the piston is below the opening, the piston is moving upward in the cylinder, and combustion products are discharged from the exhaust outlet port when the outlet port valve is open due to the exhaust gas pressure. In the second exhaust stage, while the piston continues to move upward in the cylinder beyond the opening in the circumferential wall of the cylinder, the outlet port valve is closed, and the remaining combustion products in the combustion chamber are discharged around or through the exhaust valve. The piston is movable downward in the cylinder during the intake stroke after the exhaust stroke is completed, whereby more air can be inhaled into the combustion chamber by cleaner exhaust with the remaining combustion pressure and combustion products minimized (similar to a conventional engine, fuel is inhaled into the combustion chamber by a fuel injector during the compression stroke at an appropriate timing).

[0009] An ignition plug is provided and can ignite the air / fuel mixture in the combustion chamber to cause a power stroke. The outlet port valve may be a lead valve in the exhaust outlet port. Generally, the outlet port valve is configured to open based on a pressure difference, and when the pressure in the combustion chamber is higher than the pressure in the exhaust outlet port, the valve is in an open state.

[0010] Preferably, the region between the opening and the circumferential wall of the cylinder is smooth without sharp edges to reduce and ideally avoid turbulence.

[0011] A method of modifying an engine is also disclosed, in which an exhaust outlet port having an opening in the peripheral wall of the cylinder between the bottom and top of the piston is provided. The exhaust stroke is formed as a two-stage exhaust stroke by connecting an outlet port valve to the exhaust outlet port, and this outlet port valve opens based on a pressure difference when the upper surface of the piston is below the opening in the peripheral wall of the cylinder and the piston is moving upward toward the upper side of the cylinder. In the first exhaust stage, the combustion products are discharged through the outlet port valve to the exhaust outlet port.

[0012] The cylinder for an engine of the present invention includes a peripheral wall defining a combustion chamber; a piston that moves into the combustion chamber toward the first side of the cylinder, usually the upper side, during the compression and exhaust strokes, and moves toward the second side of the cylinder, usually the opposite bottom side, during the intake stroke in which air is inhaled into the combustion chamber and the power stroke in which the air-fuel mixture in the combustion chamber is ignited; an intake valve that regulates the flow of air into the combustion chamber during the intake stroke; and an exhaust valve that regulates the flow of combustion products from the combustion chamber to the outside of the combustion chamber. The cylinder also includes an exhaust outlet port having an opening in the peripheral wall between the bottom and top of the piston, and an outlet port valve associated with the exhaust outlet port.

[0013] Therefore, the exhaust stroke is a two-stage exhaust stroke. In the first exhaust stage, when the upper surface of the piston is below the opening in the peripheral wall and the piston is moving upward toward the upper side of the cylinder and the outlet port valve is open, the combustion products are discharged from the exhaust outlet port. In the second exhaust stage after the first exhaust stage, while the piston continues to move upward beyond the opening in the peripheral wall of the cylinder, the outlet port valve is closed, and the remaining combustion products in the combustion chamber are discharged around or through the exhaust valve. The same modification as described above for the engine can also be applied to the cylinder.

Brief Description of the Drawings

[0014] The present invention will be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements:

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0015] Refer to the accompanying drawings. The same reference numbers refer to the same or similar elements. FIG. 1 is a schematic diagram of the intake stroke of the engine of the present invention, which is similar to the conventional intake stroke of a four-stroke engine. Since the difference between the engine of the present invention and the conventional engine lies mainly in the exhaust cycle, any modifications to the intake stroke of the conventional engine can also be applied to the present invention. Although a single cylinder is shown, it is understood that the engine can include a plurality of cylinders in a conventional arrangement such as in-line or V-shaped, for example.

[0016] As shown in FIG. 1 showing the intake stroke, the engine includes a cylinder 8 and a piston 4 that is movable up and down within an internal space defined by the peripheral wall of the cylinder 8. The piston 4 is provided with a connecting rod 5 that connects the piston 4 to the crankshaft 6. The crankshaft 6 rotates clockwise as indicated by the arrow, and the piston moves downward as indicated by the arrow during the intake stroke. The intake valve 1 at the upper part of the cylinder 8 is in the open position, and air is drawn through the conduit into the combustion chamber 3 portion of the internal space defined by the peripheral wall of the cylinder 8 between the upper surface of the piston 4 and the upper surface of the cylinder 8.

[0017] The advantage of the present invention based on the structure of the cylinder 8 is that the combustion products from the previous combustion stroke are removed much more significantly than in a conventional engine, so that more air can be introduced into the cylinder during the intake stroke. Since the volume of the combustion chamber 3 is finite, by further removing the combustion products, this volume can be filled with more air and fuel for the next combustion, increasing the energy production. Also, the residual pressure in the combustion chamber decreases, and the back pressure on the piston also decreases.

[0018] The spark plug 7 is provided in the cylinder 8, which represents any mechanism for generating a spark to ignite the gas in the combustion chamber 3. The intake valve 1 and the exhaust valve 2 (shown in the closed position) can be any conventional valve for the engine, but are preferably valves of the type disclosed in U.S. Patent No. 10,787,939 (Patent Document 1).

[0019] The engine also includes an exhaust outlet port 9 extending from an opening on the side of cylinder 8. This opening is arranged to be above the upper surface of piston 4 when piston 4 is in the lower position. An outlet port valve 10, such as a reed valve or other suitable valve or equivalent valve, is arranged in the exhaust outlet port 9. As shown in FIG. 1, the opening has a curved chamfered edge starting from the edge of the side surface, inner surface or peripheral wall of cylinder 8 and extending to the inlet or inner surface of exhaust outlet port 9. The entire transition region 11 between the inlet of exhaust outlet port 9 and the edge of the side surface and inner surface of the cylinder is preferably made smooth without sharp edges to reduce turbulence (the fabrication or configuration of engine components without sharp edges is disclosed in U.S. Patent No. 10,787,939 (Patent Document 1)). A reed valve is a type of check valve that restricts the gas flow in one direction and opens and closes when the pressure on each side changes. Its latest products are often composed of flexible metals or composite materials (glass fiber or carbon fiber). Therefore, reed valve 10 allows the flow from combustion chamber 3 to exhaust outlet port 9 and prevents the flow from exhaust outlet port 9 to combustion chamber 3.

[0020] FIG. 2 shows the compression stroke, in which piston 4 moves upward as indicated by the arrow on piston 4, intake valve 1 moves to the closed position, and exhaust valve 2 remains in the closed position.

[0021] FIG. 3 shows the power stroke in which spark plug 7 ignites the air-fuel mixture in combustion chamber 3. While both intake valve 1 and exhaust valve 2 are in the closed position, piston 4 moves downward as indicated by the arrow. During the compression stroke, as will be described below, since the residue of the previous combustion is almost completely discharged, the air-fuel mixture becomes cleaner. This reduces the remaining combustion products, improving fuel efficiency. When combustion is improved, misfires are reduced or ideally no misfires occur. The power obtained from the fuel and the exhaust volume increases. Also, the combustion of the fuel is better, faster, more complete and more efficient.

[0022] Figures 4 and 5 show how the engine operates using the additional exhaust outlet port 9 and the reed valve 10. Specifically, in the first stage of the exhaust stroke, after the piston 4 has moved downward to the lowest position in the power stroke shown in Figure 3 (the position where the cam of the crankshaft is at the bottom dead center), it then moves upward. In this downward movement, the piston 4 passes along the inlet through the exhaust outlet port 9, but since the exhaust outlet port 9 is closed by the valve 10, no combustion products flow out of the combustion chamber 3 during the power stroke. However, when the piston 4 passes through the exhaust outlet port 9, the valve 10 is moved to the open position by the pressure in the combustion chamber 3 and opens, and the combustion products (exhaust gas) flow into the exhaust outlet port 9 across the transition region 11 without sharp edges and are discharged from the combustion chamber 3. Figures 4 and 6 show the valve 10 in the open position. The configuration and arrangement of the valve 10 can be attached to the upper part of the exhaust outlet port 9 as shown in the figure, or can be attached elsewhere. Preferably, the valve 10 should open inwardly, for example, as shown in the figure, so as not to interfere with the movement of the piston 4. The position of the valve 10 relative to the opening of the exhaust outlet port 9 in the cylinder wall is not critical, but preferably close to it. The exhaust outlet port 9 may have a tubular structure.

[0023] As the piston 4 continues to move upward during the exhaust stroke and reaches the position where the cam of the crankshaft is at the position called the top dead center, the piston 4 closes the valve 10 when it passes by the opening of the exhaust outlet port 9 (in the configuration shown in the drawing) and reaches a position above the opening of the exhaust outlet port 9. Figure 7 shows that the valve 10 is in the closed position. Next, the exhaust valve 2 opens (it does not open in the first stage of the exhaust stroke), and the remaining exhaust gas is discharged through the exhaust valve 2 or around the exhaust valve 2 into the exhaust pipe.

[0024] An additional exhaust port is provided in the cylinder 8, and a valve is disposed in this exhaust port, so that a two-stage exhaust stroke is proposed in which the additional exhaust port is combined with the normal exhaust port from the cylinder and used at different timings. Thus, not all of the exhaust gas is discharged from the normal exhaust port, i.e., the exhaust valve 2 at the upper part of the cylinder 8 (i.e., on the same side as the intake valve 1 of the cylinder 8). Rather, a part of the exhaust gas is first discharged from the combustion chamber 3 through the exhaust outlet port 9 via the open valve 10, and then the remaining exhaust gas is discharged from the combustion chamber through the exhaust conduit around the exhaust valve 2.

[0025] The advantages of the two-stage exhaust stroke obtained by the presence of an additional exhaust outlet port communicating with the combustion chamber in the cylinder according to the position of the piston 4 include that the opening of the exhaust outlet port 9 does not always communicate with the combustion chamber 3. Rather, when the upper surface of the piston 4 is below the position where the exhaust outlet port 9 connects to the peripheral wall of the cylinder 8 defining the combustion chamber 3, the exhaust outlet port 9 and the combustion chamber 3 communicate. Otherwise, when the piston 4 is beside or above the position where the exhaust outlet port 9 connects to the peripheral wall of the cylinder 8 defining the combustion chamber 3, the exhaust outlet port 9 and the combustion chamber 3 do not communicate. Rather, the remaining exhaust gas in the combustion chamber 3 is discharged into the exhaust conduit only from around the exhaust valve 2.

[0026] The opening and closing timings of the intake valve 1 and the exhaust valve 2 are controlled by a control unit (not shown) based on the movement of the piston 4, or there may be a structural part or assembly that opens and closes the intake valve 1 and the exhaust valve 2 based on the movement of the piston 4. In either case, the intake valve 1 opens only when the inflow of air into the combustion chamber 3 is desired with respect to the position of the piston 4, and closes when such an inflow of air is inappropriate or not desired. Similarly, the exhaust valve 2 opens only when the outflow of exhaust gas from the combustion chamber 3 is desired with respect to the position of the piston 4, and closes when such an outflow is inappropriate or not desired.

[0027] Advantages include improved removal of exhaust gas from the combustion chamber, quicker removal of exhaust gas from combustion chamber 3, and more complete removal of exhaust gas from combustion chamber 3. As a result, the air-fuel mixture burns better and more completely. Also, since the backpressure on the piston is significantly reduced, the engine efficiency is increased. Further, since the emissions are significantly less compared to a standard four-stroke engine, the damage to the environment is reduced and the impact of this new engine on climate change is also lessened. Also, when both the exhaust duct and the exhaust gas from exhaust outlet port 9 are sent to the turbocharger, the energy recovery rate of the exhaust gas is increased and it can be used to enhance the performance of the turbocharger. Most of the energy is obtained from the combustion gas discharged from exhaust outlet port 9, and since the backpressure of piston 4 is minimized, the energy from the combustion gas discharged from around exhaust valve 2 is much less. Therefore, exhaust outlet port 9 has a much more important function than exhaust valve 2. A joint can be provided to connect exhaust outlet port 9 and the exhaust duct related to exhaust valve 2 to a common duct. This duct can be directed towards the turbocharger to recover energy from the exhaust gas and supply power to a compressor or other device.

[0028] Therefore, by providing a two-stage exhaust stroke, the fuel efficiency is improved, the engine efficiency is improved, and emissions and pollution are reduced compared to conventional engines.

[0029] Figures 8 - 12 relate to another type of engine to which the two-stage exhaust stroke can be applied. This engine is generally known as an Atkinson cycle engine. Conceptually, the Atkinson engine has a variable stroke length provided by a multi-link connecting rod between the piston and the flywheel. The advantage of the Atkinson engine lies in the power stroke, but it has a drawback in the exhaust stroke. The Atkinson cycle is suitable for hybrid vehicles because the electric motor of the hybrid vehicle compensates for the losses in the exhaust stroke.

[0030] The Atkinson cycle delays the closing of the intake valve until the piston has completed 20 to 30 percent of its upward movement during the compression stroke. As the piston rises, part of the fresh charge is pushed back into the intake manifold, so the cylinder is not completely filled, resulting in a decrease in output. After ignition, there is an advantage when the piston begins to descend during the expansion or power stroke. The combination of a shortened intake stroke and a full-length expansion stroke squeezes out more work for each increase in fuel.

[0031] FIG. 8 is a schematic view of the intake stroke of the engine of the present invention based on an Atkinson engine, and is similar to the conventional intake stroke of a four-stroke engine utilizing the Atkinson concept. Since the difference between the engine of the present invention and the conventional engine lies mainly in the exhaust cycle, any modification of the intake stroke of the conventional Atkinson engine can also be applied to the present invention. Although a single cylinder is shown, it is understood that the engine can include a plurality of cylinders in a conventional arrangement such as in-line or V-shaped.

[0032] As shown in FIG. 8, the engine includes a cylinder 8 and a piston 4 that is movable up and down within the internal space defined by the cylinder 8. The piston 4 is connected to a connecting portion 20 by a connecting rod 5. The connecting portion 20 includes a cam and a shaft, similar to a typical Atkinson engine, but the description of the connecting portion 20 is not necessary for understanding the function of the present invention. Generally, the connecting portion 20 rotates the crankshaft 6 clockwise as indicated by the arrow, and the piston moves downward as indicated by the arrow during the intake stroke. An intake valve 1 is also shown, and since this intake valve 1 is in the open position, air is drawn through a conduit into the combustion chamber 3 portion of the internal space defined by the cylinder 8 between the upper surface of the piston 4 and the upper surface of the cylinder 8 that defines the internal space (similar to a conventional engine, fuel is injected into the combustion chamber 3 by a fuel injector). The spark plug 7 is on the upper surface of the cylinder 8 that defines the combustion chamber and represents any mechanism for generating a spark to ignite the gas in the combustion chamber 3.

[0033] Unlike a conventional Atkinson engine, the engine includes an exhaust outlet port 9 extending from an opening on the side of cylinder 8. This opening is arranged to be above the upper surface of piston 4 when piston 4 is in the lower position (see Fig. 11). A valve 10, such as a reed valve, is arranged in exhaust outlet port 9. The transition region 11 between the inlet of exhaust outlet port 9 and the inner surface of the side of cylinder 8 is preferably made smooth without sharp edges around exhaust outlet port 9, thereby reducing turbulence (the concept of constructing or configuring engine parts without sharp edges is disclosed in U.S. Patent No. 10,787,939 (Patent Document 1)).

[0034] Fig. 9 shows the compression stroke, in which piston 4 moves upward as indicated by the arrow on piston 4, intake valve 1 moves to the closed position, and exhaust valve 2 remains in the closed position. The valve 10 of exhaust outlet port 9 is in the closed position together with exhaust valve 2 during the compression stroke.

[0035] Fig. 10 shows the power stroke in which spark plug 7 ignites the air-fuel mixture in combustion chamber 3. While both intake valve 1 and exhaust valve 2 are in the closed position, piston 4 moves downward as indicated by the arrow. The valve 10 of exhaust outlet port 9 is in the closed position together with exhaust valve 2 also during the power stroke. Piston 4 is above the position where exhaust outlet port 9 opens into the tubular wall defining cylinder 8.

[0036] Figures 11 and 12 show how the engine operates using the additional exhaust outlet port 9 and the reed valve 10. Specifically, in the first stage of the exhaust stroke, after the piston 4 moves downward and reaches the bottom position in the power stroke shown in Figure 10, it then moves upward. In this downward movement, the piston 4 passes by the opening to the exhaust outlet port 9, but since this opening is closed by the piston 4, no combustion products flow out from the combustion chamber 3 during the power stroke. However, when the piston 4 reaches the lowest position (or at least a position below the opening of the exhaust outlet port 9 into the combustion chamber 3), the valve 10 is moved to the open position by the pressure in the combustion chamber 3 and opens, and the combustion products (exhaust gas) flow into the exhaust outlet port 9 through above or beside the transition region 11 without sharp edges from the combustion chamber 3 and are discharged from the combustion chamber 3. Figure 6 shows the valve 10 in the open position.

[0037] When the piston 4 continues to rise to the uppermost position during the exhaust stroke, the piston 4 closes the valve 10 when it passes from a position below the opening of the exhaust outlet port 9 to a position above the opening of the exhaust outlet port 9 (the configuration shown in the drawing). Figure 7 shows that the valve 10 is in the closed position. The exhaust valve 2 then opens (it is not open in the first stage of the exhaust stroke), and the remaining exhaust gas is discharged from around the exhaust valve 2 into the exhaust conduit.

[0038] The advantages of the structure of the cylinder 8 with the above-mentioned additional outlet port and the valve arranged in this outlet port also apply equally to the Atkinson engine configuration in Figures 8 - 12.

[0039] In the engine structure shown and described above in the drawings, in addition to the general exhaust port associated with the exhaust valve on the same side as the intake valve of the cylinder, there is a single additional exhaust outlet port that opens into the combustion chamber. This same structure can be used in any type of engine, regardless of the number, parts, or type of combustion chambers. That is, an additional exhaust outlet port can be added to a cylinder equipped with any number of exhaust valves. That is, for any engine having one combustion chamber, the engine can be reconfigured according to the present invention by providing an additional outlet port at a position on the opposite side of the piston rather than above the piston along the wall defining the combustion chamber, and the opening to this outlet port can be opened or closed based on the position of the piston. This outlet port is connected to the combustion chamber through an opening between a point above the piston when the piston is in the lowest position in the cylinder and a point below the piston when the piston is in the highest position in the cylinder. In this way, when part or all of the upper surface of the piston is below the opening, combustion products are discharged through the outlet port, and then, when the piston is above the opening, the remaining combustion products pass through the exhaust valve and / or around the exhaust valve and are discharged. The teachings of the present invention are not limited to a specific engine, and in particular, are not limited to the engines disclosed herein.

[0040] Furthermore, although only one exhaust outlet port 9 is shown, this is considered to be a preferred embodiment. A plurality of exhaust outlet ports can also be used.

[0041] The position and shape of the opening of the exhaust outlet port 9 on the peripheral wall of the cylinder 8 are also not limited to those shown in the drawings, and the position of the opening on the peripheral wall can be changed as necessary, for example, based on the type and structure of the engine. However, the piston 4 should be configured with a solid side wall at least along the portion along the opening so that the opening is surely closed when the piston 4 is above the opening and unnecessary gas flow is prevented.

[0042] The present invention can be applied to retrofit or modify an existing engine including a crankshaft coupled to a piston via a connecting rod as shown in FIGS. 1 to 7, or a multi-link connection assembly as shown in FIGS. 8 to 12.

[0043] In this method, an exhaust outlet port 9 having an opening in the peripheral wall of the cylinder is provided at a position between the bottom and the top of the piston. The exhaust stroke is formed as a two-stage exhaust stroke by connecting an outlet port valve 10 to the exhaust outlet port 9. This valve is configured to open and discharge combustion products from the outlet port valve 10 to the exhaust outlet port 9 in a first stage where the upper surface of the piston 4 is below the opening in the peripheral wall of the cylinder 8 and the piston is moving towards the first side of the cylinder 8. In the illustrated embodiment, the first side of the cylinder 8 is the upper surface or the upper side, but depending on the orientation or configuration of the cylinder 8, the first side may be another side.

[0044] This method also involves discharging the remaining combustion products from the combustion chamber 3 around or through the exhaust valve 2 while the piston 4 continues to move towards the first side of the cylinder 8 when the piston 4 is above the opening in the peripheral wall of the cylinder 8 in a second exhaust stage after the first exhaust stage. During the second exhaust stage, the outlet port valve 10 is in a closed state. In some embodiments, an ignition plug 7 is provided to ignite the air-fuel mixture in the combustion chamber to cause a power stroke. The exhaust port valve 10 may be arranged in the exhaust outlet port 9 as shown, or coupled to the exhaust outlet port 9 by another type of arrangement. In another embodiment, a lead valve needs to be arranged in the exhaust outlet port 9 to couple the outlet port valve 10 to the exhaust outlet port 9.

[0045] Generally, the exhaust port valve 10 is associated with the exhaust outlet port 9, which means that it is coupled to the exhaust outlet port 9 in order to enable the desired function, i.e., to open based on a pressure difference to allow flow from the combustion chamber 3 to the exhaust outlet port 9. Also, the exhaust port valve 10 is preferably configured to open based on a pressure difference, such that when the pressure in the combustion chamber 3 becomes higher than the pressure in the exhaust outlet port 9, the valve 10 is in an open state.

[0046] Although specific embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that the invention can be changed and modified without departing from the broader aspects of the invention, and thus the purpose of the appended claims is to cover all changes and modifications that are within the true spirit and scope of the invention. Further, the absence of a structure in the drawings may, in some embodiments, be considered to indicate that such a structure is intentionally absent and omitted in the engine or other configurations disclosed herein. The absence of such a structure may, in some embodiments, provide advantages.

Claims

1. An engine comprising: a cylinder having a peripheral wall defining a combustion chamber; a crankshaft; a piston movable within said cylinder toward a first side of said cylinder during a compression stroke and an exhaust stroke, and movable toward a second side of said cylinder opposite said first side during an intake stroke in which air is drawn into said combustion chamber and a power stroke in which an air / fuel mixture within said combustion chamber is ignited and said crankshaft to which said piston is connected rotates as a result of combustion of the air / fuel mixture, the order of said strokes being intake, compression, power, and exhaust; an intake valve associated with said cylinder for regulating the flow of air into said combustion chamber; an exhaust valve associated with said cylinder for regulating the flow of combustion products out of said combustion chamber; an exhaust outlet port having an inlet communicating with and spaced from an opening in the peripheral wall of said cylinder at a position between the lowermost and uppermost positions of said piston, said opening in the peripheral wall of said cylinder being larger than said inlet of said exhaust outlet port and having a chamfered edge curved throughout the entire transition region between the edge of the peripheral wall of said cylinder and said inlet of said exhaust outlet port; and a reed valve within said exhaust outlet port; whereby the exhaust stroke is a two-stage exhaust stroke, and in a first exhaust stage, when the upper surface of said piston is below said opening and said piston is moving toward said first side of said cylinder and said reed valve is open, combustion products are discharged from said exhaust outlet port, and in a second exhaust stage after said first exhaust stage, while said piston continues to move toward said first side of said cylinder beyond the opening in the peripheral wall of said cylinder, said reed valve is closed and the remaining combustion products within said combustion chamber are discharged around said exhaust valve. characterized by an engine.

2. The engine according to claim 1, further comprising a spark plug for igniting the air / fuel mixture within said combustion chamber to produce a power stroke.

3. ​ The lead valve is configured to open based on a pressure difference, such that when the pressure in the combustion chamber becomes higher than the pressure in the exhaust outlet port, the lead valve is in an open state. The engine according to claim 1, characterized in that.

4. The piston has a solid wall in a portion passing along the opening. The engine according to claim 1, characterized in that.

5. The engine according to claim 1, further comprising a connecting rod connecting the piston to the crankshaft.

6. The engine according to claim 1, further comprising a multi-link connecting rod connecting the piston to the crankshaft.

7. The intake valve and the exhaust valve are on the first side of the cylinder. The engine according to claim 1, characterized in that.

8. The lead valve is attached to the upper part of the exhaust outlet port inside the entire transition region between the edge of the peripheral wall of the cylinder and the inlet of the exhaust outlet port. The engine according to claim 1, characterized in that.

9. An arrangement of cylinders: The peripheral wall of the cylinder defining the combustion chamber; A piston that is movable toward the first side of the cylinder in a compression stroke and an exhaust stroke within the cylinder, and in an intake stroke in which air is inhaled into the combustion chamber, and an air / fuel mixture in the combustion chamber is ignited. The order of the strokes is intake stroke, compression stroke, power stroke, and exhaust stroke. A piston; An intake valve for regulating the flow of air into the combustion chamber; An exhaust valve for regulating the flow of combustion products in the combustion chamber out of the combustion chamber; An exhaust outlet port that communicates with an opening in the peripheral wall of the cylinder and has an inlet spaced from the opening at a position between the lowermost and uppermost parts of the piston. The opening in the peripheral wall of the cylinder is larger than the inlet of the exhaust outlet port, and has a beveled edge that curves across the entire transition region between the edge of the peripheral wall of the cylinder and the inlet of the exhaust outlet port. An exhaust outlet port; and A lead valve in the exhaust outlet port; Comprising As a result, the exhaust stroke becomes a two-stage exhaust stroke. In the first exhaust stage, when the upper surface of the piston is below the opening of the peripheral wall of the cylinder and the piston is moving toward the first side of the cylinder, and the lead valve is open, the combustion products are discharged from the exhaust outlet port. In the second exhaust stage after the first exhaust stage, while the piston continues to move toward the first side of the cylinder beyond the opening of the peripheral wall of the cylinder, the lead valve is in a closed state, and the remaining combustion products in the combustion chamber are discharged from around the exhaust valve. An arrangement of a cylinder, characterized by the above. Claim 10 The arrangement of the cylinder according to claim 9, characterized in that the intake valve and the exhaust valve are on the first side of the cylinder. Claim 11 The arrangement of the cylinder according to claim 9, characterized in that the lead valve is attached to the upper part of the exhaust outlet port inside the entire transition region between the edge of the peripheral wall of the cylinder and the inlet of the exhaust outlet port.

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