HK1171801A - Two-stroke engine - Google Patents

Abstract

The two-stroke engine (10) has multiple intake passages (40a, 40c) extending from the external intake port through the crankcase (12), which separate the intake air from the air and oil vapor in the crankcase (12).The piston (44) has one or more corresponding inlet pipes (48a, 48b) hanging down from it, which are nested with the crankcase intake passage (40a, 40c) as the piston reciprocates.All intake air passes through these channels (40a, 40c) and is isolated from the remaining material in the space of the crankcase.The intake air passes through the coaxial lift valve (52) on the piston top (54) and enters the combustion chamber (58).The fuel is provided through traditional direct injection or port injection, and one or more traditional spark plugs are used for ignition.The exhaust gas is discharged from the combustion chamber (58) through the lift valve (60) on the cylinder head (18), which is driven by a rocker (68) and a push rod (66) originating from the crankshaft driven cam (62).

Description

Two-stroke engine

[ technical field ] A method for producing a semiconductor device

The present invention relates generally to internal combustion engines and, more particularly, to a two-stroke reciprocating internal combustion engine having internal structure that prevents intake air from mixing with oil.

[ background of the invention ]

Reciprocating internal combustion engines have been the mainstay of power machinery for a considerable period of time due to their power output relative to size and weight, fuel economy, and ease of operation. However, such engines also have their drawbacks. For example, two-stroke engines, which exhaust and compress gases during the upstroke of the piston and produce work and intake during the downstroke of the piston, may provide a relatively high output power relative to the size and weight of the engine due to the efficiency of the power stroke for each revolution of the crankshaft. However, such engines have historically been relatively inefficient in terms of fuel consumption and emissions, due to the lack of separation of the four different phases of a cycle of such engines, such that each phase has its own stroke, as in a conventional four-stroke engine (otto cycle).

Another problem with the two-stroke engine is that such conventional engines initially introduce intake air into the crankcase and then the downstroke of the piston on a power stroke will compress the crankcase and allow the intake air to enter the cylinder in preparation for the next power stroke. Since the crankcase is essentially always filled with air, a conventional oil-filled crankcase for lubrication of a four-stroke engine is not available for lubrication of the two-stroke engine. Accordingly, in a two-stroke engine, the oil in the crankcase may be mixed with fuel during fueling, or the oil in the crankcase may be injected into the engine during operation. As the oil enters the engine, it is combusted to produce power and exits the engine as exhaust gas, which results in oil contamination of the air-fuel mixture. Although such engines can provide a higher output power than their own weight and the weight of the vehicle on which they are mounted can be relatively reduced, many applications do not allow the use of such engines using their operating principle, even if this is the case, due to the current demands on engine emissions.

It is therefore desirable to provide a two-stroke engine that overcomes the above problems.

[ summary of the invention ]

The two-stroke engine includes a system for separating the intake air from the crankcase volume to prevent contamination of the intake air by the lubricating oil in the crankcase. A pre-compression chamber or intake column is provided outside the crankcase and cylinder. A reed valve is provided at the inlet of the intake column for controlling the flow of air into the intake column. One or more additional intake passages extend along the intake column and communicate with corresponding crankcase transfer passages in the crankcase of the engine. The crankcase transfer gallery is nested and in communication with a piston transfer gallery depending from the piston. In this way all the intake air can always be completely separated from the crankcase space and the oil vapour therein.

A coaxial inlet poppet valve is disposed on the piston crown. When the intake valve at the top of this piston is open, intake air from the intake passage flows into the combustion chamber through the crankcase transfer passage and the piston transfer passage. Since fuel and oil are not mixed into intake air to be delivered into the engine, fuel can be directly injected into the combustion chamber using a conventional direct fuel injection (direct fuel injection) method. Alternatively, port fuel injection (port injection) may be used to inject fuel into the intake port of the engine. There are one or more conventional spark plugs for igniting the fuel and air mixture to produce energy. If the engine is designed for compression ignition, the engine will operate like a diesel engine once initial ignition has occurred.

An exhaust poppet valve is provided on the cylinder head to exhaust the mixed exhaust gas produced after the power stroke. The exhaust valve is driven by a rocker and a pushrod driven by a cam driven by the rotation of a crankshaft, as is conventional in the art. The drive of the exhaust valve may also be provided by an upper cam driven by the crankshaft mechanism, if desired.

Most of the drawings depict a single cylinder air cooled engine. However, it will be appreciated that the operating principles described herein may also be extended to multi-cylinder water cooled engines within the scope of the present invention.

These and other features of the present invention will become more apparent upon further consideration of the following drawings and specification.

[ description of the drawings ]

Fig. 1 is a left side view of a two-stroke engine of the present invention, showing the basic structure of the engine.

FIG. 2 is a top view of the engine of FIG. 1 showing an exemplary spark plug and fuel injection configuration.

Fig. 3 is a cross-sectional view taken along line 3-3 of fig. 1.

Fig. 4A is a cross-sectional view taken along line 4A-4A of fig. 2, showing the engine with the piston at top dead center.

Fig. 4B is a cross-sectional view taken along line 4B-4B of fig. 2.

Fig. 5A is a right side view of the cross-section of the engine of fig. 1, which is similar to fig. 4A, but shows the crankshaft rotated 45 from the position shown in fig. 4A and 4B.

Fig. 5B is a cross-sectional, rear side view of the engine of fig. 1, which is similar to fig. 4B, but showing the crankshaft rotated 45 from the position shown in fig. 4A and 4B.

FIG. 6A is a right side elevational view, in cross-section, of the engine of FIG. 1, which is similar to FIG. 4A, but showing the crankshaft rotated 90 degrees from the position shown in FIGS. 4A and 4B

Fig. 6B is a cross-sectional, rear side view of the engine of fig. 1, which is similar to fig. 4B, but showing the crankshaft rotated 90 from the position shown in fig. 4A and 4B.

Fig. 7A is a right side view of the cross-section of the engine of fig. 1, which is similar to fig. 4A, but shows the crankshaft rotated 135 ° from the position shown in fig. 4A and 4B.

Fig. 7B is a rear side elevational view of the section of the engine of fig. 1, which is similar to fig. 4B, but showing the crankshaft rotated 135 deg. from the position shown in fig. 4A and 4B.

FIG. 8A is a right side view, in cross-section, of the engine of FIG. 1, which is similar to FIG. 4A, but shows the crankshaft rotated 180 from the position shown in FIGS. 4A and 4B, i.e., the piston is at bottom dead center.

FIG. 8B is a rear side elevational view, in cross-section, of the engine of FIG. 1, similar to FIG. 4B, but showing the crankshaft rotated 180 from the position shown in FIGS. 4A and 4B, i.e., the piston is at bottom dead center.

Fig. 9A is a right side view of the cross-section of the engine of fig. 1, which is similar to fig. 4A, but shows the crankshaft rotated 225 deg. from the position shown in fig. 4A and 4B.

Fig. 9B is a rear side elevational view of the cross-section of the engine of fig. 1, which is similar to fig. 4B, but showing the crankshaft rotated 225 deg. from the position shown in fig. 4A and 4B.

Fig. 10A is a right side view of the cross-section of the engine of fig. 1, which is similar to fig. 4A, but shows the crankshaft rotated 270 from the position shown in fig. 4A and 4B.

Fig. 10B is a rear side elevational view of the section of the engine of fig. 1, which is similar to fig. 4B, but showing the crankshaft rotated 270 from the position shown in fig. 4A and 4B.

FIG. 11A is a right side view of the cross-section of the engine of FIG. 1, which is similar to FIG. 4A, but shows the crankshaft rotated 315 from the position shown in FIGS. 4A and 4B.

FIG. 11B is a rear side elevational view of the cross-section of the engine of FIG. 1, which is similar to FIG. 4B, but showing the crankshaft rotated 315 from the position shown in FIGS. 4A and 4B.

FIG. 12 is a right side perspective view of a multi-cylinder liquid cooled two stroke cycle engine in an alternative embodiment of the invention.

Like reference characters designate corresponding features throughout the several views.

[ detailed description ] embodiments

The two-stroke engine (two-stroke engine) of the present invention has an internal structure that isolates air and oil vapor (oil vapor) in a crankcase (crankcase) from intake air (intake charge), which can provide a cleaner running engine than a conventional two-stroke engine. Fig. 1 provides an external left side view of an exemplary air-cooled single cylinder embodiment 10 of the two-stroke engine of the present invention, and fig. 2 through 11 provide additional external and internal views of the two-stroke engine 10.

The engine 10 includes a crankcase 12, the crankcase 12 including a crankshaft (crankshaft)14 disposed therein. A cylinder 16 extends from the crankcase 12. The cylinder 16 includes a cylinder head 18 thereon. The cylinder head 18 is provided with at least one spark plug (spark plug)20 and a fuel injector 22 (direct or port). As shown in FIG. 2, the cylinder head 18 may include a plurality of spark plugs 20.

An intake column 24 extends along the outer left side of the cylinder 16. The intake column 24 includes an inlet end 26 adjacent the cylinder head 18 and an opposing base 28 connected to the crankcase 12 and communicating with a crankcase chamber or interior fluid space 30 (shown in fig. 4A-11B), the intake column 24 defining an intake space 32 therein. At least one, and preferably two, external intake passages (ducts, etc.) 34a and 34b extend along the cylinder 16 and adjacent the intake column 24. The two outer inlet passages 34a and 34b include inlet ends that communicate with the inlet end 26 of the inlet column 24 via an inlet plenum or blower 36. Opposing bases 38a and 38b of the outer intake passages 34a and 34b extend into the crankcase 12 and communicate with inner crankcase intake passages 40a and 40b, respectively. The internal crankcase inlet passages 40a and 40b may isolate the inlet volumes 42a and 42b therein from combustion gases, oil, or other fluids within the crankcase chamber or interior 30 of the crankcase 12. The crankcase intake passages 40a and 40b extend upward from the interior of the crankcase 12 to the lower portion of the interior of the cylinder 16, respectively, and the crankcase intake passages 40a and 40b have upper portions parallel to the cylinder 16.

A piston 44 reciprocates within the cylinder 16 and is mechanically connected to a throw (crank throw) of the crankshaft 14 by a conventional connecting rod 46. The piston 44 includes at least one piston inlet passage (preferably a plurality of piston inlet passages 48a and 48 b). These piston inlet passages 48a and 48b correspond to the crankcase inlet passages 40a and 40b, respectively, and the piston inlet passages 48a and 48b will nest in the respective crankcase inlet passages 40a and 40b as the piston 44 reciprocates in the cylinder 16 when the two-stroke engine 10 is operating. The piston inlet passages 48a and 48b are hollow and each define an intake volume 50a and 50b, respectively, and the intake volumes 42a, 42b of the crankcase intake passages 40a, 40b are in substantially continuous communication with the intake volumes 50a, 50b of the piston inlet passages 48a, 48b during engine operation. Thus, it can be seen that the fixed crankcase inlet passages 40a, 40b and the piston inlet passages 48a, 48b nested therewith seal their inlet volumes 42a, 42b and 50a, 50b from the crankcase interior 30 to prevent contamination of the inlet air by oil vapors from the crankcase interior 30 during engine operation.

Fig. 4A through 11B provide a series of progressive views of the engine 10 in operation, each set of figures a and B showing the internal structure of the engine 10 at every 45 ° clockwise rotation of the crankshaft 14. It should be noted that the engine may also be designed to rotate in the opposite direction, counterclockwise, by adjusting the timing of a cam 62 (discussed further below) associated with the crankshaft 14 and correspondingly adjusting the ignition timing. The piston 44 includes a coaxial intake poppet valve 52 on a piston crown 54, the intake valve 52 alternately opening and closing ports 56a and 56b, the ports 56a and 56b extending through the piston 44 and communicating with corresponding piston inlet passages 48a and 48 b. The intake valve 52 is driven primarily by the difference in air pressure between the intake spaces 42a, 42b, 50a and 50b and the upper portion of the cylinder and the combustion chamber 58 during engine operation, although conventional return springs (not shown) may be mounted on the intake valve of the piston 44 as required. Since the operation of the intake valve 52 is dependent upon the air pressure differential between the crankcase and the upper portion of the cylinder, no mechanical timing mechanism is provided for the intake valve 52. Therefore, the intake valve 52 can operate normally regardless of the rotational direction of the engine.

An exhaust poppet valve (60) is coaxially mounted on the cylinder head 18. The exhaust valve 60 is driven by a cam 62 on the crankshaft 14, the cam 62 periodically driving a tappet (tapset) 64, the tappet 64 then reciprocating a pushrod 66. During engine operation, the pushrod 66 actuates a rocker 68 on the cylinder head 18 to cause the exhaust valve 60 to periodically reciprocate as needed. Instead of this, other mechanisms may be used to operate the exhaust valve 60, such as an upper cam driven by a rotating shaft on the crankshaft, etc. In addition, other conventional means (mechanical, electronic, pneumatic, etc.) may be used to adjust the timing of the exhaust valve 60 based on engine speed and power output.

Fig. 4A and 4B show the beginning of a cycle when the piston 44 is at a top dead center position, i.e., the throw of the crankshaft 14 is at its maximum height. In this position, both the intake valve 52 and the exhaust valve 60 are closed, maximizing the air pressure in the combustion chamber 58 for efficient operation. Since the piston 44 has lifted the piston inlet passages 48a, 48b upward, the lift of the piston 44 in the cylinder 16 maximizes the intake volume 42a, 42b, 50a, and 50b in the passages 40a, 40b and 48a, 48 b.

This also maximizes the fluid volume 30 in the crankcase 12, driving air downward from the interior volume 32 of the intake column 24. To minimize the cyclic motion of the air in the intake column 24, the crankcase 12 may be filled as much as possible with a solid space limiting filler 70 as shown in fig. 4A, 5A, 6A, etc. to minimize the fluid space 30 within the crankcase 12. This filler 70 may be a different material than the metal crankcase 12 of the engine 10, and may be a lighter plastic material as desired, so long as the internal liquid space 30 within the crankcase 12 is restricted, thereby minimizing the back and forth movement of air from the intake column 24 due to the internal space 30 of the crankcase 12. It is sufficient to leave sufficient space for the deflection of the lower end of the connecting rod 46 during its crank stroke and for the internal crankcase inlet passages 40a and 40 b.

It can be seen that during each cycle of engine operation, the air in the interior space 32 of the intake column 24 is pulsed back and forth, with the air in the crankcase space 30 being pushed up into the intake column 24 on the down stroke (downstroke) of the piston 44 and then pulled back into the crankcase space 30 on the up stroke (upstroke) of the piston 44. Since the engine cycles very fast, there is little actual mixing of air or oil in the crankcase with the intake air in the intake column. Additionally, a sliding floating plunger or separator 72 is mounted in the intake column 24 to isolate the interior space 30 in the crankcase 12 from the intake portion of the intake column 24, which further reduces the mixing. The floating separator 72 slides up and down in the intake column 24 to separate air in the upper portion of the intake column 24, which communicates with the intake air in the external intake passages 34a and 34b through an intake plenum 36, from air in the internal space 30 in the crankcase every cycle of operation of the engine 10. As shown in fig. 4B, the piston 44 is at its highest point, and thus may pull the floating separator 72 down to its lowest point in the intake column 24. The air pressure in the upper space 32 of the intake column 24 is temporarily stabilized at this time, and then the air pressure in the upper space 32 of the intake column 24 begins to rise again as the piston 44 begins to descend and push the air in the crankcase 12 back into the lower portion (lower portion) of the intake column 24. Accordingly, the inlet valve 74 (e.g., carbon fiber spring reed type valve, etc.) in the inlet plenum 36 is closed. As shown in fig. 4B through 11B, a relatively thin bracket 76 extends across the throat of the intake plenum 36 to limit excessive movement of the inlet valve 74 during closing. The bracket 76 is shown substantially completely in the top view of fig. 2.

Fig. 5A and 5B show the operating condition of the engine after the crankshaft 14 has rotated 45 ° clockwise from the position in fig. 4A and 4B, in which the piston has begun its downstroke due to the combustion gas pressure at the top of the cylinder 16. The exhaust valve 60 is closed in this position due to the orientation of the cam 62, and the intake valve 52 of the piston crown 54 is also closed due to the higher air pressure in the combustion chamber 58 and the upper portion of the cylinder 16 compared to the air pressure in the crankcase volume 30 and the lower portion of the intake column 24. However, it can be seen that downward travel of the piston 44 also reduces the interior space 30 of the crankcase 12 and the lower portion of the cylinder 16, and thus forces air within the crankcase 12 back to the lower portion of the intake column 24. This causes the floating separator 72 in the intake column 24 to begin to rise, as well as the air pressure in the upper portion of the intake column 24 and the crankcase and piston conduits or passages 40a, 40b, 48a, 48b, which causes the reed valve 74 in the intake plenum 36 to close against its external ambient air pressure.

In fig. 6A and 6B, the crankshaft 14 has rotated 90 ° clockwise from the initial top dead center position of fig. 4A, 4B. Combustion gas pressure continues to force the piston 44 downward within the cylinder 16 while the exhaust valve 60 and the intake valve 52 remain closed. The downward travel of the piston 44 continues to push the floating separator 72 toward the intake port 26 of the intake column 24 while the interior space 30 of the crankcase 12 continues to decrease. The reduction in space within the compression nested crankcase passages or passages 40a, 40b and piston passages or passages 48a, 48b also causes the gas pressure in the upper portion of the intake column 24 to rise, causing the reed valve 74 to close, but the gas pressure in the space below the crankcase 12 and the floating separator 72 is slightly greater than the gas pressure in the spaces within the passages or passages 40a, 40b, 48a and 48b, thereby causing the floating separator 72 to float somewhat within the intake column 24.

Fig. 7A and 7B show a position of the engine 10 in the cycle wherein the crankshaft 14 has rotated 135 ° clockwise from the initial top dead center position of fig. 4A, 4B. The exhaust valve 60 remains closed because the lobe of the cam 62 has not yet rotated to a position where it can begin to lift the lifter 64. Even though the space within the cylinder 16 is enlarged and the air pressure within the cylinder 16 is reduced as the piston 44 continues its downstroke, the air pressure within the cylinder is still somewhat higher than the air pressure within the crankcase 12 and the ambient air pressure and the intake valve 52 remains closed. As the piston 44 continues its downstroke and the volume 30 in the crankcase 12 continues to decrease, the air pressure in the crankcase 12 will further push the floating separator 72 up in the intake column 24. This causes the reed valve 74 to remain closed.

Fig. 8A and 8B show the positions of the internal components of the engine 10 when the piston 44 reaches bottom dead center (bottom dead center), i.e., the crankshaft 14 rotates 180 ° clockwise from top dead center in fig. 4A and 4B. It can be seen that the lobe of the cam 62 has rotated to a position where it can begin to lift the lifter 64, thereby actuating the exhaust valve mechanism to open the exhaust valve 60 and relieve the residual pressure in the cylinder 16. In this position, the interior space 30 in the crankcase 12 reaches a minimum value, so that a maximum pressure is generated in the crankcase 12. This will cause the floating separator 72 to reach its highest point in the intake column 24 and therefore the space in the upper part of the intake column 24 below the reed valve 74 will reach a minimum. This lowest point of travel of the piston 44 also causes the space within the compression nesting passages 40a, 40b, 48a and 48b communicating with the upper portion of the interior space of the intake column 24 to reach a minimum, which further increases the pressure in these passages above the air pressure within the cylinder 16, particularly when the exhaust valve 60 is already open. The exhaust valve 60 is opened so that the air pressure therein is almost the same as the ambient air pressure, while the air pressure in the intake passages 40a, 40b, 48a and 48b is always accumulated, so that the air pressure difference existing therebetween pushes open the intake valve 52 of the piston crown 54, allowing fresh intake air (fresh intake air) to flow into the cylinder 16. The ports 56a, 56b extending through the piston 44 preferably do not lie in a diametric vertical plane through the piston 44, but rather preferably extend upwardly and inwardly at an angle away from the center of the piston. Thus, the intake air may form a swirl or spiral inside the cylinder 16 due to binding by the inner wall of the cylinder. The swirling or spiraling action of the intake air may be clockwise or counterclockwise depending on the direction of the ports 56a, 56b through the piston 44. The exhaust valve 60 opens as the intake air enters the cylinder 16, which may assist in expelling the exhaust gas from the cylinder 16 to reduce the entrainment of limited intake air in the cylinder 16 for the next combustion event cycle.

In fig. 9A and 9B, the crankshaft 14 has rotated approximately 225 ° from the initial top dead center position of fig. 4A and 4B, at which time the piston 44 begins its upstroke in cylinder 16. The lobe of the cam 62 is not yet rotated enough to allow the lifter 64 to descend, so the exhaust valve 60 remains open to some extent. The relatively small spaces 42a, 42b, 50a and 50b in the crankcase inlet passages 40a, 40b and the piston inlet passages 48a, 48b will still cause the gas pressure in these passages to be relatively high, thus forcing more gas into the cylinder 16 through the open inlet valve 52 on the piston crown 54. On the other hand, the higher gas pressure in the crankcase 12 drives the floating separator 72 upward in the intake column 24, so that the upper portion of the intake column 24 decreases. The reduction in space of the intake conduits or passages 40a, 40b, 48a and 48b, and the reduction in space of the upper portion of the intake column 24, allows higher air pressure to remain in these intake passages 40a, 40b, 48a and 48b, and thus the intake reed valve 74, to remain closed.

Fig. 10A and 10B show positions in a cycle of the engine 10 reached by the crankshaft 14 rotating 270 ° or three-quarters clockwise from the initial top dead center position in fig. 4A and 4B. In this position of the cycle, the lobe of the cam 62 has rotated past the tappet 64, thus causing the exhaust valve 60 to close. The closing of the exhaust valve 60 and the upstroke of the piston 44 in the cylinder 16 causes the intake valve 52 of the piston crown 54 to close. For the next combustion event and power stroke (powerstroke), compression of fresh air charge in the closed cylinder is initiated. The piston inlet ducts or passages 48a and 48b extend from the respective fixed crankcase inlet passages 40a and 40b, thus increasing the spaces 42a, 42b and 50a, 50b therein. This results in a reduction in the air pressure in the upper portion of the intake valve 24. As the lift of the piston 44 increases the space in the crankcase 12 and the air pressure decreases, the floating separator 72 in the intake column 24 is pulled downward, further reducing the air pressure in the intake column 24. As a result, the air pressure of the upper portion of the intake valve 24 is reduced to a level lower than the ambient air pressure, which causes the intake reed valve 74 to open, as shown in fig. 10B.

Finally, FIGS. 11A and 11B show the position of the internal components of engine 10 when the crankshaft 14 is rotated 315 clockwise from the top dead center position of FIGS. 4A and 4B. In this position, both the exhaust valve 60 and the intake valve 52 remain closed, thus further compressing the newly charged air in the top of the cylinder 16 for subsequent fuel injection and ignition. The space 30 in the crankcase 12 is increasing such that the floating separator 72 in the intake column 24 is pulled downward. This will increase the space above the inlet column 24 and correspondingly decrease its pressure. At the same time, the piston inlet ducts 48a, 48b are further pulled out of the crankcase inlet ducts 40a, 40b, thus enlarging the spaces 42a, 42b, 50a and 50b therein, thereby further reducing the gas pressure in these ducts. The relatively low air pressure in the conduits or passages 40a, 40B, 48a and 48B and in the upper portion of the intake column 24 causes the intake reed valve 74 to open further as shown in FIG. 11B. Shortly after this position, preferably just before piston 44 again reaches top dead center, injector 22 injects fuel and spark plug 20 (fig. 2) initiates ignition, thereby resuming operation of the two-stroke cycle.

Accordingly, it can be seen that a two-stroke engine 10, as well as other engine embodiments, utilizing the same or similar separation means to separate the intake air from the gases in the crankcase, provides an internal combustion power plant that substantially eliminates contamination of the intake air with crankcase oil vapors as occurs in conventional two-stroke engines. The engine 10 described above is described as a single cylinder air-cooled engine. However, it will be appreciated that the operating principles described herein may be applied to engines of many other configurations.

For example, fig. 12 shows a multi-cylinder inline engine (multi-cylinder inline engine) having a single crankcase 112, wherein each cylinder 116 is provided with a water jacket around its circumference to provide liquid cooling. The air-cooled multi-cylinder engine and the water-cooled single-cylinder engine obviously can also use the air inlet system of the invention. Although the engine 110 shown in fig. 12 is a four cylinder inline engine, it will be appreciated that other cylinder arrangements, such as V-shaped, horizontally opposed, and star-shaped, may be used with the intake system described above.

Another benefit of the system of isolating the intake air from the polluting gases in the crankcase is that it has been difficult to achieve before in a multi-cylinder two-stroke engine. Conventional multicylinder two-stroke engines require that the space in the crankcase corresponding to each cylinder be partitioned. This is because initial compression of the intake air in the crankcase is required as the piston travels down its power stroke. Since the pistons in a balanced engine are at different positions in their respective cycles, and since the times at which the pistons reciprocate in their cylinders are different, the intake air in the crankcase beneath the pistons will no longer pulsate or flow back and forth, and thus a single space in the crankcase will not be able to provide such initial compression. The multi-cylinder two-stroke engine 110 solves this problem by isolating the intake air from the variable space in the crankcase through a novel intake system.

Additionally, although the engine shown in fig. 1 through 11B has a plurality of spark plugs, it will be appreciated that the engine may be operated using the two-stroke compression ignition (Diesel) principle, if desired. Such an engine requires only one ignition plug (glow plug) for starting, and does not require multiple spark plugs as in the engine 10 of fig. 2. Accordingly, the two-stroke engine 10, as well as other embodiments, may be adapted for general use in a number of different fields and operating environments.

It is to be understood that the invention is not limited to the embodiments described above, but encompasses all embodiments within the scope of the following claims.

Claims (20)

1. A two-stroke engine, comprising:

a crankcase defining a fluid space therein;

a crankshaft disposed within the crankcase;

at least one cylinder extending from the crankcase;

a piston disposed within the cylinder, the piston being mechanically coupled to the crankshaft;

at least one intake passage disposed within the crankcase, the intake passage having an intake space therein;

at least one piston inlet port depending from said piston, said piston inlet port having an intake air space therein, said piston inlet port being nested with said intake air passage, said intake air passage and said piston inlet port sealing the intake air space therein from the space within said crankcase.

2. The two-stroke engine according to claim 1, further comprising:

an intake column disposed outside the cylinder and the crankcase, the intake column having a base communicating with the crankcase, an inlet end disposed opposite the base, and an intake space therein; and

a free-floating separator disposed within the intake column, the floating separator separating the intake space of the intake column into a first portion between the inlet end and the floating separator and a second portion between the floating separator and the crankcase, the floating separator inhibiting intermixing of the first and second portions of the intake space of the intake column.

3. The two-stroke engine according to claim 1, wherein the piston has a piston crown, the two-stroke engine further comprising:

a cylinder head disposed atop the cylinder;

an intake poppet valve coaxially disposed atop said piston; and

and the exhaust poppet valve is coaxially arranged on the cylinder cover.

4. The two-stroke engine according to claim 1, further comprising a solid fluid space restriction filling disposed within a partial space of the crankcase.

5. The two-stroke engine according to claim 1, further comprising:

an exhaust cam provided on the crankshaft;

a cylinder head disposed atop the cylinder;

a pushrod extending between the exhaust cam and the cylinder head;

the rocker is arranged on the cylinder cover and is mechanically connected with the push rod; and

and the exhaust poppet valve is coaxially arranged on the cylinder cover and is mechanically connected with the rocker.

6. The two-stroke engine according to claim 1, wherein a plurality of cylinders extend from the crankcase.

7. The two-stroke engine according to claim 1, further comprising a cooling jacket disposed about the at least one cylinder.

8. A two-stroke engine, comprising:

a crankcase defining a fluid space therein;

a crankshaft disposed within the crankcase;

at least one cylinder extending from the crankcase;

a piston disposed within the cylinder, the piston being mechanically coupled to the crankshaft;

an intake column disposed outside the cylinder and the crankcase, the intake column having a base communicating with the crankcase, an inlet end disposed opposite the base, and an intake space therein; and

a free-floating separator disposed within the intake column, the floating separator separating the intake space of the intake column into a first portion between the inlet end and the floating separator and a second portion between the floating separator and the crankcase, the floating separator inhibiting intermixing of the first and second portions of the intake space of the intake column.

9. The two-stroke engine according to claim 8, further comprising:

at least one intake passage disposed within the crankcase, the intake passage having an intake space therein;

at least one piston inlet port depending from said piston, said piston inlet port having an intake air space therein, said piston inlet port being nested with said intake air passage, said intake air passage and said piston inlet port sealing the intake air space therein from the space within said crankcase.

10. The two-stroke engine according to claim 8, wherein the piston has a piston crown, the two-stroke engine further comprising:

a cylinder head disposed atop the cylinder;

an intake poppet valve coaxially disposed atop said piston; and

and the exhaust poppet valve is coaxially arranged on the cylinder cover.

11. The two-stroke engine according to claim 8, further comprising a solid fluid space restriction filler disposed within a partial space of the crankcase.

12. The two-stroke engine according to claim 8, further comprising:

an exhaust cam provided on the crankshaft;

a cylinder head disposed atop the cylinder;

a pushrod extending between the exhaust cam and the cylinder head;

the rocker is arranged on the cylinder cover and is mechanically connected with the push rod; and

and the exhaust poppet valve is coaxially arranged on the cylinder cover and is mechanically connected with the rocker.

13. The two-stroke engine according to claim 8, wherein a plurality of cylinders extend from the crankcase.

14. The two-stroke engine according to claim 8, further comprising a cooling jacket disposed about the at least one cylinder.

15. A two-stroke engine, comprising:

a crankcase defining a fluid space therein;

a crankshaft disposed within the crankcase;

at least one cylinder extending from the crankcase;

a cylinder head disposed atop the cylinder;

a piston disposed within the cylinder, the piston being in mechanical communication with the crankshaft, the piston having a piston crown;

an intake poppet valve coaxially disposed atop said piston; and

and the exhaust poppet valve is coaxially arranged on the cylinder cover.

16. The two-stroke engine according to claim 15, further comprising:

at least one intake passage disposed within the crankcase, the intake passage having an intake space therein;

at least one piston inlet port depending from said piston, said piston inlet port having an intake air space therein, said piston inlet port being nested with said intake air passage, said intake air passage and said piston inlet port sealing the intake air space therein from the space within said crankcase.

17. The two-stroke engine according to claim 15, further comprising:

an intake column disposed outside the cylinder and the crankcase, the intake column having a base communicating with the crankcase, an inlet end disposed opposite the base, and an intake space therein; and

a free-floating separator disposed within the intake column, the floating separator separating the intake space of the intake column into a first portion between the inlet end and the floating separator and a second portion between the floating separator and the crankcase, the floating separator inhibiting intermixing of the first and second portions of the intake space of the intake column.

18. The two-stroke engine according to claim 15, further comprising a solid fluid space restriction filler disposed within a partial space of the crankcase.

19. The two-stroke engine according to claim 15, further comprising:

an exhaust cam provided on the crankshaft;

a cylinder head disposed atop the cylinder;

a pushrod extending between the exhaust cam and the cylinder head;

the rocker is arranged on the cylinder cover and is mechanically connected with the push rod; and

and the exhaust poppet valve is coaxially arranged on the cylinder cover and is mechanically connected with the rocker.

20. The two-stroke engine according to claim 15, further comprising:

a single crankcase having a plurality of cylinders extending therefrom; and

a cooling jacket disposed about the plurality of cylinders.