Internal-combustion engines – Two-cycle – Pump and cylinder adjacent
Reexamination Certificate
1999-12-03
2001-07-10
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Two-cycle
Pump and cylinder adjacent
Reexamination Certificate
active
06257180
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to internal combustion engines and, more particularly, to an internal combustion engine having a superior cycle comprised of three events, namely, compression, combustion, and ventilation, accomplished in two strokes with greater efficiency than has heretofore been made available through the prior art.
2. Description of the Background
Many internal combustion engines operate on a cycle known as the Otto Cycle which has been known since as far back as the year 1801. Whether one is explaining the operation of a two cycle engine or a four cycle engine, the Otto Cycle defines four basic events that occur within the engine during the cycle, namely, intake (or induction), compression, power (or ignition), and exhaust.
In a four stroke engine, approximately one stroke (180 degrees of the 720 degree cycle) is devoted to each event. While modern high speed four stroke engines have attempted to incorporate near simultaneous intake and exhaust, these events still require two separate strokes in a four stroke engine. In such an arrangement, all of the airflow occurs at the top of the cylinder, which tends to help to cool the cylinder head, but which fails to cool the cylinder body. Further, in such a configuration, the power stroke can comprise at best no more than 22% of the cycle, thus limiting the overall power output potential of the engine.
In a two stroke engine, power, exhaust, and intake all occur on the down stroke, followed by additional exhaust and compression on the up stroke. The familiar two stroke internal combustion engine defines four distinct events within the combustion cylinder during its cycle. Beginning with the ignition of the fuel/air mixture in the cylinder, pressure rises above the cylinder head to drive the piston downward through the cylinder. While traveling downward through the cylinder, the piston uncovers an exhaust port to expose the cylinder (which is under high pressure) to near atmospheric pressure, and the combustion products previously held within the cylinder force themselves out of the cylinder through the exhaust port. The piston continues its downward travel through the cylinder to then uncover an intake port prior to the piston reaching its bottom dead center position. During the return stroke (or “up stroke”), the intake port is first closed by the piston. However, for at least a brief period, the exhaust port remains open as the piston continues to travel upward in its return stroke. Thus, some of the fresh air taken in through the intake port and a portion of any fuel that has thus far been mixed into that air is likewise forced out of the exhaust port until the piston closes the exhaust port by passing it during its return stroke. Once the exhaust port is closed, the remaining air and fuel mixture is compressed. Once compression is completed, the two cycle process is finished, and ignition of the fuel/air mixture occurs once again to start the cycle anew. Unfortunately, the period of the cycle during which the piston travels from its bottom dead center position to the top of the exhaust port results in a significant loss of fresh air and fuel which could be used as part of the combustion product.
Another feature of a typical two stroke engine is that the crankcase in a two stroke engine provides a volume of space in which much of the carburetion takes place. This configuration prevents the use of a volume of oil splashing around in the crankcase as is normally the case with a traditional four stroke engine. Thus, in a two stroke engine, oil must be mixed with the fuel prior to its introduction into the cylinder, creating either an additional burden on the user who must mix the fuel and oil prior to use, or requiring more complex fuel and oil delivery systems, while producing an environmentally unfriendly exhaust product which includes burnt oil as a combustion byproduct.
It would therefore be advantageous to provide an improved internal combustion engine which enables the air being inducted into a combustion chamber to participate in cooling the entire cylinder, which increases the efficiency of previously known two cycle engines without requiring the complexity and additional weight associated with four cycle engines, and which prevents the need to use a fuel/oil mixture in a two cycle engine configuration.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an internal combustion engine which avoids the disadvantages of the prior art.
It is another object of the present invention to provide an internal combustion engine which introduces cool air into a combustion cylinder to contribute to cooling the entire length of the combustion cylinder.
It is still another object of the present invention to provide an internal combustion engine which increases the efficiency of previously known two cycle engines without increasing the complexity or weight to that of four cycle engine.
It is yet another object of the present invention to provide an internal combustion engine having the benefits of a traditional four cycle engine while extending the power stroke to 25 to 40 percent of the total cycle.
It is still yet another object of the present invention to provide an internal combustion engine which increases the amount of air charge which may be retained within a combustion cylinder to participate in the combustion event over what has been previously available in traditional two stroke engines.
It is even yet another object of the present invention to provide an internal combustion engine which eliminates the need to mix oil with fuel in a traditional two stroke engine configuration.
According to the present invention, the above-described and other objects are accomplished by providing an internal combustion engine having two parallel cylinders, namely, an induction cylinder and a power cylinder, whereby the power, ventilation (comprising simultaneous intake and exhaust), and compression events within the power cylinder completely define the cycle of the engine, with induction in the induction cylinder being an auxiliary and incidental function to the cycle within the power cylinder, such that engine cooling and fuel efficiency are improved over prior art internal combustion engines. Within the combustion cylinder, an intake port is provided at the top of the cylinder, which port in turn is equipped with a one way, pressure responsive transfer valve for allowing air to flow into the combustion cylinder when pressure therein falls below the pressure in the induction cylinder.
The cycle of the engine of the instant invention is established as follows. Ignition of the fuel air mixture at the head of the power cylinder initiates the power or down stroke of the power piston. Thereafter, exhaust and intake occur nearly simultaneously from somewhat before the bottom dead center position of the power piston until somewhat after the bottom dead center position of the power piston. Finally, the trapped air within the power cylinder is compressed during the remainder of the power piston's up stroke through the remainder of the cycle. Thus, in the configuration of the instant invention, unlike a traditional four stroke engine in which exhaust and intake occur in two separate strokes, no entire stroke is devoted to either of these events, or to both combined. Further, the placement of the exhaust port in the combustion cylinder and the phase difference between the induction piston and the power piston of the instant invention enables the power stroke to be never less than 25 percent, and up to as much of 40 percent, of the entire cycle. Still further, because carburetion is not required for the instant invention, and thus because the crankcase is not involved in the process of inducting air and fuel into the combustion chamber, oil may be circulated in the crankcase as in a traditional four stroke engine, such that mixing of oil with the fuel becomes unnecessary and a cleaner exhaust product is produced over what has been previously attai
Huynh Hai
Kamen Noah P.
Law offices of Royal W. Craig
LandOfFree
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