Two-stroke internal combustion engine with isolated crankcase

Abstract
A two-stroke engine with an isolation chamber. The isolation chamber has a pressure-sensitive wall attached to or slidably mounted within the isolation chamber. The pressure-sensitive wall is substantially impervious to air, oil, and the fuels used in an internal combustion two-stroke engine. When the piston of the engine moves away from the crankcase, a vacuum is created in the crankcase. This draws the pressure-sensitive wall toward the crankcase within the fluid communication circuit, which movement of the pressure sensitive wall also pulls air into the intake side of the isolation chamber through a one-way valve or time induction mechanism. When the piston moves toward the crankcase, the increased pressure within the crankcase forces the pressure-sensitive wall away, fluidwise, from the crankcase and thus pushing air from the isolation chamber into the combustion chamber. The pressure-sensitive wall therefore is effective in preventing oil from flowing into the combustion chamber from the crankcase. Further, a modified piston having a lower oil ring precludes oil from being pushed by pressurized air from leaving the crankcase, squeezing past the piston, and reaching the transfer port and the exhaust port. Consequently, pollution is minimized in a two-stroke engine utilizing this novel design approach.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates to a two-stroke internal combustion engine, especially such an engine with a pressure-sensitive wall contained within a chamber for isolating the crankcase from the combustion chamber.




2. Description of the Related Art




In a conventional two-stroke internal combustion engine, the vacuum caused by a piston moving away from the crankcase draws a mixture of fuel, air, and oil into the crankcase through a one-way valve or timed induction mechanism such as a piston port or rotary valve. Increased pressure produced by the piston moving toward the crankcase forces the mixture of fuel, air, and oil into the piston cylinder on the side of the piston away from the crankcase and, therefore, into the combustion chamber, which is at the portion of the piston cylinder that is the most distant from the crankcase, because such carbureted fuel cannot escape through the one-way valve or a now closed induction mechanism.




The crankcase is used as a compressor. This requires the crankcase to have relatively close tolerances between the crank and the crankcase, itself. It is also required that the crankcase be sealed. These factors isolate the crankcase from any lubrication that may be in other parts of the engine. Therefore, a secondary lubrication system is necessary. However, any oil in the crankcase would readily be pushed into the combustion chamber. Therefore, to minimize the oil that is pushed into the combustion chamber, oil is continuously added to the crankcase, but only in small quantities. In conventional two-stroke engines this is accomplished either by oil injection or by utilizing fuel which has been pre-mixed with a suitable quantity of oil. But no matter how the lubrication is achieved, oil will be introduced into the combustion chamber and combusted. And during the combustion process, such oil creates considerable smoke and other pollution.




Additionally, when a traditional two-stroke internal combustion engine compresses the mixture of fuel, air, and oil (before the transfer ports open), some of the fuel and oil can go past the piston skirt and into the exhaust port unburned. This adds to hyrocarbon pollution of the atmosphere and limits the attainable crankcase pressure.




U.S. Pat. No. 4,248,185 of Eric Jaulmes employs a membrane 7 in the crankcase pump 1 of a two-cycle engine, but the sole purpose of that membrane 7 is to divide the crankcase pump 1 into two chambers 8 and 9. Chamber 8 contains the crankshaft 6 and the connecting rod 4 and would, therefore, also contain oil for lubrication. Since carbureted air passes through chamber 8 on its way to the piston cylinder 2, oil (whether pre-mixed with fuel or injected into the crankcase) would thereby be introduced into the piston cylinder 2. Pure air passes through chamber 9 to reach the piston cylinder 2; but because of the oil-containing carbureted air, the membrane 7 does not isolate the piston cylinder 2 from the oil in the crankcase. In the alternate embodiment of FIGS. 7 through 9, the carbureted air passes through chamber 9; and pure air goes through chamber 8. Thus, as explained in lines 25 through 28 of column 4, it is necessary to provide separate lubrication, i.e., lubrication could not be accomplished by oil pre-mixed with the fuel. The oil that would be separately added for lubrication would then travel with the air to the piston cylinder 2.




U.S. Pat. No. 5,291,866 of David R. Kosa applies to a Pulse Charger 40 which supplies air from the crankcase 24 of a four-cycle internal combustion engine to the intake system 18 of that engine. It is asserted that a baffle 120 between the crankcase 24 and the pulse charger 40 “aids in keeping any liquid from entering” the pulse charger and that an “additional oil separator 140 . . . may also be included in order to separate crankcase oil from the pulsed air charge prior to the pulsed air charge entering carburetor or fuel injection system 52 [which carburetor or fuel injection system 52 is placed between the pulse charger 40 and the intake system 18]. Oil separator 140 can be of the centrifugal type, the baffle type or any other type of separator known in the art.” The baffle 120 and oil separator 140, however, attempt to remove oil from air which such oil has already infiltrated rather than precluding such oil from ever entering the air.




The supercharger in U.S. Pat. No. 3,672,172 of Gary L. Hammond appears to operate in a fashion rather similar to that of U.S. Pat. No. 5,291,866. “To avoid any undesired entrainment of oil in the supercharging air, an air-oil separator such as, for example, louvered baffle, wire mesh screen, loose packed metal shavings or the like, or combinations thereof, is employed [between the crankcase 26 or 122 and the inlet valve 12 or intake port 104]. The separator should not unduly restrict airflow but should trap entrained oil.” In attempting to remove oil from air which such oil has already infiltrated rather than precluding such oil from ever entering the air, the devices of U.S. Pat. Nos. 5,291,866 and 3,672,172 do, however, necessarily limit airflow.




Some two-stroke internal combustion engines avoid introducing oil into the carbureted air by not using the crankcase as a pump. Instead, these engines utilize superchargers, which are heavy, expensive, and inefficient because the blower is always turning and putting a load on the engine even when there is no demand from the engine for fuel or air, i.e., when the transfer ports are closed.




SUMMARY OF THE INVENTION




The present invention utilizes the pressure and vacuum cycles created within the crankcase of a crankcase compression two-stroke internal combustion engine to force air into the piston cylinder, also termed the combustion chamber, of the engine. A flexible diaphragm, bellows, or floating piston is, though, utilized to isolate the air that travels to the combustion chamber from the crankcase. Therefore, no oil ever enters the combustion chamber.




As the piston moves away from the crankcase, a vacuum is created within the crankcase. This draws the flexible diaphragm, bellows, or floating piston within an isolation chamber toward the crankcase, creating a vacuum on the side of the diaphragm, bellows, or floating piston away from the crankcase and drawing a mixture of fuel and air (or plain air if either a fuel injection system that injects fuel into the combustion chamber is utilized or a charge former is between the isolation chamber and the transfer port) through a one-way valve or timed induction mechanism into the isolation chamber on the side of the diaphragm, bellows, or floating piston that is away from the crankcase.




When the piston moves toward the crankcase, the increased pressure pushes the diaphragm, bellows, or floating piston in the isolation chamber away from the crankcase. Because the mixture of fuel and air or pure air on the side of the diaphragm away from the crankcase cannot escape through the one-way valve or timed induction mechanism, such mixture of fuel and air or pure air is forced into the piston cylinder and, therefore, into the combustion chamber.




Such mixture of fuel and air or pure air is, therefore, pumped into the combustion chamber without ever being exposed to oil that lubricates the crankcase and without the use of a supercharger.




Preferably, the piston is designed with a full-length skirt around the entire perimeter of the piston and with at least one ring around the piston. This ring is placed so that it is always between all ports and the crankcase in order to preclude oil that is either maintained within and/or circulated through the crankcase from passing between the piston and the wall of the piston cylinder and thereby entering the exhaust port or the transfer port. (Oil in the exhaust port would be heated to such an extent that it would smoke or be pushed into the surrounding environment; oil in the transfer port would be pushed into the combustion chamber and create smoke during combustion which would then be exhausted to the surrounding environment.)











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

illustrates the Two-stroke Engine with Isolated Crankcase utilizing a diaphragm as the pressure-sensitive wall.





FIG. 2

portrays the Two-stroke Engine with Isolated Crankcase employinging a bellows as the pressure-sensitive wall.





FIG. 3

shows the Two-stroke Engine with Isolated Crankcase using a floating piston as the pressure-sensitive wall.





FIG. 4

depicts the embodiment of

FIG. 1

wherein oil is circulated through the crankcase by a pump.











DESCRIPTION OF THE PREFERRED EMBODIMENT




As illustrated in

FIG. 1

, the preferred embodiment of the Two-stroke Engine with Isolated Crankcase primarily adds to the components of a traditional two-stroke internal combustion engine an isolation chamber


8


having a pressure-sensitive wall. The pressure-sensitive wall may be a flexible diaphragm


9


as illustrated in

FIG. 1

, a bellows


109


as portrayed in

FIG. 2

, or a floating piston


209


as shown in FIG.


3


.




The isolation chamber


8


is attached to a sealed crankcase


6


and communicates with the crankcase


6


through an aperture termed the crankcase-side aperture


17


in the isolation chamber


8


and an aperture


18


in the crankcase


6


. Preferably, a hollow member termed the activation passage


14


is used to connect the isolation chamber


8


to the crankcase


6


.




The pressure-sensitive wall is substantially impervious to air, oil, and the fuels used in an internal combustion engine and, with the inner surface


19


of the isolation chamber


8


, forms a barrier that is substantially impervious to air, oil, and the fuels used in an internal combustion engine. When a diaphragm


9


or a bellows


109


is utilized, the diaphragm


9


or bellows


109


is attached to the inner surface


19


of the isolation chamber


8


in such a manner that oil and air cannot pass from the side termed the crankcase side


10


of the isolation chamber


8


that is toward the crankcase


6


to the side termed the intake side


11


of the isolation chamber


8


that is away from the crankcase


6


. Preferably, the diaphragm


9


is attached near the center of the isolation chamber whereas the bellows


109


is attached near the crankcase-side aperture


17


. The floating piston


209


is slidably in contact with the inner surface


19


of the isolation chamber


8


so that neither oil nor air can pass between the floating piston


209


and the inner surface


19


of the isolation chamber


8


. This can be accomplished with a floating piston seal


103


which can be a flared or flared and flexible rim


103


that is an integral part of the floating piston


209


; a ring, termed a piston ring,


103


; or any other form of seal that is well known in the art.




The ring


103


is preferably a pressure ring. The floating piston


209


is preferably nonmetallic, e.g., carbon fiber or nylon, which is beneficially lighter than a metallic piston


209


. This is possible because the pressure, heat, and quantity of oil to which the floating piston


209


is exposed are considerably lower than the pressure, heat, and quantity of oil to which the piston


1


, discussed below, is subject.




Attachment of the diaphragm


9


or the bellows


109


to the isolation chamber


8


could, e.g., be done with an adhesive or, alternatively, through, friction if the isolation chamber


8


is split in half and clamped together with a portion of the diaphragm


9


or the bellows


109


inserted between the halves of the isolation chamber


8


.




A second aperture termed the intake aperture


22


in the isolation chamber


8


is on the intake side


11


of the isolation chamber


8


. Connected to the isolation chamber


8


and communicating with the isolation chamber


8


through the intake aperture


22


is a flow regulator. The flow regulator can be either a one-way valve


13


that permits air to pass into, but not escape from, the intake side


21


of the isolation chamber


8


or a timed induction mechanism, such as a rotary valve, that is open when the piston


1


of the engine is moving away from the crankcase


6


but closed when the piston


1


of the engine is moving toward the crankcase


6


so that air will flow into, but not escape from, the intake side


21


of the isolation chamber


8


.




A third aperture


23


is located in the intake side


11


of the isolation chamber


8


. Also, an aperture designated the transfer port


24


exists in the wall


25


of a piston cylinder


26


, which piston cylinder is attached to the crankcase


6


. The isolation chamber


8


is attached to the wall


25


of the piston cylinder


26


in such a manner that the isolation chamber


8


communicates with the piston cylinder


26


and, therefore, with the combustion chamber


16


, which is at the portion of the piston cylinder


26


that is the most distant from the crankcase


6


, through the third aperture


23


and the transfer port


24


. Preferably the isolation chamber


8


is connected to the wall


25


of the piston cylinder


26


with a hollow member termed the transfer passage


2


.




A piston


1


is slidably mounted within the piston cylinder


26


and is connected, as is well known in the art, to the crankshaft


27


.




Also in the wall


25


of the piston cylinder


26


is an additional aperture termed an exhaust port


28


. The top


32


of the exhaust port


28


is higher than the top


33


of the transfer port


24


so that, on the movement of the piston


1


toward the crankcase


6


, the top


31


of the piston


1


will reach the top


32


of the exhaust port


28


before reaching the top


33


of the transfer port


24


to facilitate the movement of combustion gases from the combustion chamber


16


through the exhaust port


28


.




Although for purposes of clarity of illustration only a single third aperture


23


of the isolation chamber


8


, a single transfer port


24


in the wall


25


of the piston cylinder


26


, and a single transfer passage


2


are shown, it is preferable to have multiple transfer ports


24


and multiple transfer passages


2


so as to enhance the efficiency in the scavenging of exhaust gases.




Carbureted air can be fed into the flow regulator, carburetion can occur between the isolation chamber


8


and the transfer port


24


, or fuel can be injected into the combustion chamber


16


.




The piston


1


has a means for precluding oil pushed by pressurized air from leaving the crankcase


6


and reaching the transfer port


24


and the exhaust port


28


by passing between the piston


1


and the wall


25


of the piston cylinder


26


. The bottom


34


of the piston


1


must have a full-length skirt


35


around the entire perimeter of the piston


1


. A piston seal


3


, which is preferably an oil ring


3


but which can be a flared or flared and flexible rim must be around the piston


1


sufficiently close to the bottom


34


of the piston that the piston seal


3


is always between the crankcase


6


and the bottoms


29


,


30


of the exhaust port


28


and the transfer port


24


.




At least one traditional pressure or compression ring


7


is also located around the piston


1


near the top


31


of the piston


1


; and, preferably, a pressure or compression ring


4


is placed around the piston


1


above and near the piston seal


3


.




As can be understood from the preceding discussion, the pressure-sensitive wall, i e., the diaphragm


9


, the bellows


109


, or the floating piston


209


isolates the oil within the crankcase


6


from the combustion chamber


16


.




As the piston


1


moves away from the crankcase


6


, the pressure is decreased within the crankcase


6


, thereby, when a diaphragm


9


is utilized, drawing the diaphragm


9


toward the crankcase so that, when the piston


1


has reached its upper limit of travel, the diaphragm


9


is approximately in position B, as shown in the ghost illustration of FIG.


1


. (Similarly, if a bellows


109


were used, the closed end of the bellows


109


would be drawn toward the crankcase


6


; and if a floating piston


209


were employed, the piston would be pulled toward the crankcase


6


.) This naturally draws air through the flow regulator, preferably the one-way valve


13


, and the intake aperture


22


into the intake side


11


of the isolation chamber


8


. Then, the movement of the piston


1


toward the crankcase


6


, increases the pressure within the crankcase


6


, thereby pushing the diaphragm


9


(or the closed end of the bellows


109


or the floating piston


209


) away from the crankcase


6


so that, when the piston


1


has reached its lower limit of travel, the diaphragm


9


is approximately in position A, as depicted in the ghost illustration of FIG.


1


.




Because the air on the intake side


11


of the diaphragm


9


(or the bellows


109


or the floating piston


209


) cannot escape through the flow regulator, preferably the one-way valve


13


, such air is forced into the combustion chamber


16


.




But since temperature changes within the crankcase


6


can interfere with the synchronization of movement between the piston


1


and the diaphragm


9


(or the bellows


109


or the floating piston


209


), it is preferable to have a vent aperture


36


within the isolation chamber


8


, the crankcase


6


, or the activation passage


14


on the crankcase side


10


of the pressure-sensitive wall, which vent aperture


36


communicates between the surrounding environment and the isolation chamber


8


, the crankcase


6


, and the activation passage


14


. This is accomplished by having the vent tube


15


attached to a vent aperture


36


, which vent aperture can be in the crankcase side


10


of the isolation chamber


8


, the crankcase


6


, or the activation passage


14


. Furthermore, to minimize the possibility of any contamination entering the vent aperture


36


, it is preferable to have a hollow vent tube


15


attached to the isolation chamber


8


, the crankcase


6


, or the activation passage


14


around the vent aperture


36


. The vent tube


15


communicates with, and leads away from, the vent aperture


36


. Optionally, a filter can be placed on the end of the vent tube


15


that is away from the vent aperture


36


.




Because of the sealed nature of the crankcase


6


, if the temperature within the crankcase


6


increases rapidly as the piston


1


begins to travel upward, the diaphragm


9


(or the bellows


109


or the floating piston


209


) will not begin moving toward the crankcase


6


immediately when the piston


1


begins to move away from the crankcase


6


. Similarly, if the temperature within the crankcase


6


decreases rapidly as the piston


1


begins its movement toward the crankcase


6


, the diaphragm


9


(or the bellows


109


or the floating piston


209


) will not begin moving away from the crankcase


6


immediately when the piston


1


begins to move toward the crankcase


6


.




The vent aperture


36


is selected to have a diameter of such a size that the vent aperture


36


will eliminate the delay in movement of the diaphragm


9


(or the bellows


109


or the floating piston


209


) produced by temperature changes within the crankcase


6


while not permitting such a quantity of air to enter or leave the crankcase side


10


of the isolation chamber


8


, the crankcase


6


, or the activation passage


14


that the action of the diaphragm


9


(or the bellows


109


or the floating piston


209


) would be impeded to such an extent that performance of the engine would be negatively measurably affected.




Optionally, through any means that is well known in the art, the vent aperture


36


can be coordinated with the engine speed, e.g., the vent tube


36


can be closed when the throttle is closed and also when the engine is operating at very high speeds.




Air introduced into the combustion chamber


16


through the pumping action of the diaphragm


9


(or the bellows


109


or the floating piston


209


) not only provides the air for combustion, but also scavenges the exhaust products of combustion through the exhaust port


28


.




Although only a single piston cylinder


26


has been illustrated, an isolation chamber


8


can similarly successfully be employed with multiple cylinder two-stroke engines because the portions of the crankcase


6


associated with a given piston cylinder


26


would be sealed from and, therefore, would not communicate with one another. In such a case, each piston cylinder


26


would have its own isolation chamber


8


.




Also, rather that using just one isolation chamber


8


, it would be possible to use multiple isolation chambers


8


for a given piston cylinder


26


.




As another option, if all pistons


1


of a multiple-cylinder two-stroke engine fire at substantially the same time, a single isolation chamber


8


can communicate with all the piston cylinders


26


; and it would not be necessary to have the portions of the crankcase


6


associated with different piston cylinders


26


sealed from one another.




Oil can either be held within the crankcase


6


or, as illustrated in

fig. 4

, circulated through the crankcase


6


by any means that is well known in the art for conventional four-stroke engines, such as by a pump


50


.



Claims
  • 1. A two-stroke internal combustion engine with isolated crankcase, which comprises:a sealed crankcase having an aperture and a crankshaft; a piston cylinder attached to said crankcase, said piston cylinder having a combustion chamber and also having a wall with a transfer port which has a top and a bottom and an exhaust port that has a top and a bottom with the top of the exhaust port being higher than the top of the transfer port; a piston slidably mounted within said piston cylinder, said piston connected to the crankshaft of said crankcase, and having a top, a bottom a piston seal around said piston sufficienty close to said bottom of said piston that said piston seal is always between (1) said crankcase and (2) the bottoms of the transfer port and of the exhaust port, and a pressure ring located around said piston near the top of said piston; an isolation chamber, said isolation chamber having an inner surface, a crankcase side, an intake side, a pressure-sensitive wall, said pressure-sensitive wall forming a barrier between said crankcase side and said intake side, and being substantially impervious to air, oil, and the fuels used in an internal combustion engine, a crankcase-side aperture on the crankcase side of said isolation chamber, an intake aperture on the intake side of said isolation chamber, and a third aperture on the intake side of said isolation chamber, said isolation chamber communicating with said crankcase through the crankcase-side aperture and the aperture in said crankcase, and said isolation chamber communicating with said piston cylinder through the third aperture and the transfer port; and a flow regulator connected to said isolation chamber and communicating with said isolation chamber through the intake aperture so that air may pass into, but will not escape outward through said flow regulator from, the intake side of said isolation chamber.
  • 2. The two-stroke internal combustion engine with isolated crankcase as recited in claim 1, wherein:on the crankcase side of said pressure-sensitive wall, an element of the engine selected from the group consisting of (a) the isolation chamber, and (b) the crankcase, contains a vent aperture, said vent aperture communicating between the surrounding environment and said engine element, said vent aperture having a diameter of such a size that said vent aperture eliminates delay in movement of said pressure-sensitive wall produced by temperature changes within said crankcase, while not permitting such a quantity of air to enter or leave said crankcase that the action of the pressure-sensitive wall would be impeded to such an extent that performance of the engine would be measurably negatively affected.
  • 3. The two-stroke internal combustion engine with isolated crankcase as recited in claim 2, further comprising:a hollow vent tube attached around, communicating with, and leading away from said vent aperture.
  • 4. The two-stroke engine with isolated crankcase as recited in claim 3, wherein:said isolation chamber is connected to said crankcase via an activation passage; and said isolation chamber is connected to the wall of said piston cylinder with a transfer passage.
  • 5. The two-stroke internal combustion engine with isolated crankcase as recited in claim 3, wherein:the group from which the element of the engine containing the vent aperture is selected further consists of an activation passage.
  • 6. The two-stroke internal combustion engine with isolated crankcase as recited in claim 5, further comprising:a hollow vent tube attached around, communicating with, and leading away from the vent aperture in said activation passage.
  • 7. The two-stroke internal combustion engine with isolated crankcase as recited in claim 6, further comprising:a pressure ring placed around said piston at a location above and near the said piston seal.
  • 8. The two-stroke internal combustion engine with isolated crankcase as recited in claim 7, wherein:the group from which the element of the engine containing the vent aperture is selected further consists of an activation passage.
  • 9. The two-stroke internal combustion engine with isolated crankcase as recited in claim 8, further comprising:a hollow vent tube attached around, communicating with, and leading away from said vent aperture in said activation passage.
  • 10. The two-stroke internal combustion engine with isolated crankcase as recited in claim 3, further comprising:a pressure ring placed around said piston above and near said piston seal.
  • 11. The two-stroke internal combustion engine with isolated crankcase as recited in claim 2, wherein:said isolation chamber is connected to said crankcase with an activation passage; and said isolation chamber is connected to the wall of said piston with a transfer passage.
  • 12. The two-stroke internal combustion engine with isolated crankcase as recited in claim 11, wherein:the group from which the element of the engine containing the vent aperture is selected further consists of an activation passage.
  • 13. The two-stroke internal combustion engine with isolated crankcase as recited in claim 12, further comprising:a hollow vent tube attached around, communicating with, and leading away from the vent aperture in said activation passage.
  • 14. The two-stroke internal combustion engine with isolated crankcase as recited in claim 11, further comprising:a pressure ring placed around said piston above and near the said piston seal.
  • 15. The two-stroke internal combustion engine with isolated crankcase as recited in claim 14, wherein:the group from which the element of the engine containing the vent aperture is selected further consists of an activation passage.
  • 16. The two-stroke internal combustion engine with isolated crankcase as recited in claim 15, further comprising:a hollow vent tube attached around, communicating with, and leading away from the vent aperture in said activation passage.
  • 17. The two-stroke internal combustion engine with isolated crankcase as recited in claim 2, further comprising:a pressure ring placed around said piston above and near said piston seal.
  • 18. The two stroke internal combustion engine with isolated crankcase as recited in claim 1, wherein:said isolation chamber is connected to said crankcase with an activation passage; and said isolation chamber is connected to the wall of said piston cylinder with a transfer passage.
  • 19. The two-stroke internal combustion engine with isolated crankcase as recited in claim 18, wherein the element of the engine containing the vent aperture comprises of an activation passage.
  • 20. The two-stroke internal combustion engine with isolated crankcase as recited in claim 19, further comprising:a hollow vent tube attached around, communicating with, and leading away from the vent aperture in said activation passage.
  • 21. The two-stroke internal combustion engine with isolated crankcase as recited in claim 18, further comprising:a pressure ring placed around said piston above and near the said piston seal.
  • 22. The two-stroke internal combustion engine with isolated crankcase as recited in claim 21, wherein:the group from which the element of the engine containing the vent aperture is selected further consists of an activation passage.
  • 23. The two-stroke internal combustion engine with isolated crankcase as recited in claim 22, further comprising:a hollow vent tube attached around, communicating with, and leading away from the vent aperture in said activation passage.
  • 24. The two-stroke internal combustion engine with isolated crankcase as recited in claim 1, further comprising:a pressure ring placed around said piston above and near the said piston seal.
  • 25. The two-stroke internal combustion engine with isolated crankcase as recited in claim 1, wherein:said pressure-sensitive wall comprises a diaphragm attached to the inner surface of said isolation chamber in such a manner that oil and air cannot pass from the crankcase side of said isolation chamber to the intake side of said isolation chamber.
  • 26. The two-stroke internal combustion engine with isolated crankcase as recited in claim 1, wherein:said pressure-sensitive wall comprises a bellows attached to the inner surface of said isolation chamber in such a manner that oil and air cannot pass from the crankcase side of said isolation chamber to the intake side of said isolation chamber.
  • 27. The two-stroke internal combustion engine with isolated crankcase as recited in claim 1, wherein:said pressure-sensitive wall comprises a floating piston, said floating piston being slidably in contact with the inner surface of said isolation chamber so that neither oil nor air can pass between said floating piston and the inner surface of said isolation chamber.
  • 28. A two-stroke internal combustion engine with isolated crankcase, which comprises:a sealed crankcase having an aperture and a crankshaft; a piston cylinder attached to said crankcase, said piston cylinder having at the most distant portion of said piston cylinder from said crankcase, a combustion chamber and also having a wall with a transfer port which has a top and a bottom and an exhaust port that has a top and a bottom with the top of the exhaust port being higher than the top of the transfer port; a piston slidably mounted with said piston cylinder, connected to the crankshaft of said crankcase, and having a top, a bottom, a means for precluding oil pushed by pressurized air from leaving said crankcase and reaching the transfer port and the exhaust port by passing between said piston and the wall of said piston cylinder, and a pressure ring located around said piston near the top of said piston; an isolation chamber, said isolation chamber having an inner surface, a crankcase side, an intake side, a means for precluding air and oil from passing from the crankcase side to the intake side of said isolation chamber and for pumping air or air and fuel to the combustion chamber, a crankcase-side aperture on the crankcase side of said isolation chamber, an intake aperture on the intake side of said isolation chamber, and a third aperture on the intake side of said isolation chamber, said isolation chamber being attached to said crankcase and communicating with said crankcase through the crankcase-side aperture and the aperture in said crankcase, and said isolation chamber being connected to the wall of said piston cylinder and communicating with said piston cylinder through the third aperture and the transfer port; and a flow regulator connected to said isolation chamber and communicating with said isolation chamber through the intake aperture so that air may pass into, but will not escape from, the intake side of said isolation chamber.
  • 29. A process for producing a two-stroke internal combustion engine with isolated crankcase, which comprises:attaching a sealed crankcase having an aperture and a crankshaft to a piston cylinder having at the most distant portion of the piston cylinder from said crankcase, a combustion chamber and also having a wall with a transfer port which has a top and a bottom and an exhaust port that has a top and a bottom with the top of the exhaust port being higher than the top of the transfer port; slidably mounting, within said piston cylinder, a piston having a top, a bottom with a full-length skirt around the entire perimeter of the piston, a piston seal around the piston sufficiently close to the bottom of the piston that the piston seal is always between said crankcase and the bottoms of the transfer port and the exhaust port, and a pressure ring located around said piston near the top of the piston; connecting the piston to the crankshaft of the crankcase; attaching to the crankcase an isolating chamber having an inner surface, a crankcase side, an intake side, a pressure-sensitive wall, the pressure-sensitive wall being substantially impervious to air, oil, and the fuels used in an internal combustion engine and the pressure-sensitive wall, together with the inner surface of the isolation chamber, forming a barrier that is substantially impervious to oil, air, and the fuels used in an internal combustion engine, a crankcase-side aperture on the crankcase side of the isolation chamber, an intake aperture on the intake side of the isolation chamber, and a third aperture on the intake side of the isolation chamber, so that the isolation chamber communicates with the crankcase through the crankcase-side aperture and the aperture in the crankcase; connecting the isolation chamber to the wall of said piston cylinder and communicating with said piston cylinder through the third aperture and the transfer port; and connecting the isolation chamber to a flow regulator so that the isolation chamber communicates with the flow regulator through the intake aperture in order to assure that air may pass into, but will not escape from, the intake side of the isolation chamber.
  • 30. A two-stroke internal combustion engine with isolated crankcase, said engine comprising:(a) a sealed crankcase, (b) a piston cylinder attached to said crankcase, said piston cylinder having a wall defining a combustion chamber portion, a wall with a transfer port having a top and a bottom, and an exhaust port having a top and a bottom, wherein said top of said exhaust port is higher than said top of said transfer port; (c) a crankshaft mounted for operation within said crankcase; (d) a piston slidably mounted within said piston cylinder, said piston operably connected to said crankshaft said piston having a top, a bottom, a piston seal around said piston sufficiently close to said bottom in a location so that said piston seal is always between (1) said crankcase and (2) the bottoms of the transfer port and of the exhaust port, and (e) an isolation chamber, said isolation chamber having an inner surface, a crankcase side, an intake side, a pressure-sensative wall, said pressure-sensitive wall forming a barrier between said crankcase side and said intake side, and being substantially impervious to air, oil, and the fuels used in an internal combustion engine, a crankcase-side aperture on the crankcase side of said isolation chamber, an intake aperture on the intake side of said isolation chamber, and a third aperture on the intake side of said isolation chamber, said isolation chamber communicating with said crankcase through the crankcase-side aperture and the aperture in said crankcase, and said isolation chamber communicating with said piston cylinder through the third aperture and the transfer port; and (f) a flow regulator connected to said isolation chamber and communicating with said isolation chamber through the intake aperture so that air may pass into, but will not escape outward through said flow regulator from the intake side of said isolation chamber.
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