Internal-combustion engines – Oscillating cylinder
Reexamination Certificate
2001-01-25
2001-11-13
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Oscillating cylinder
C123S0470AB
Reexamination Certificate
active
06314923
ABSTRACT:
FIELD OF THE INVENTION
The field of the present invention is internal combustion engines. More particularly, the present invention relates to internal combustion engines that can be operated as two-stroke engines suitable for automotive use.
BACKGROUND OF THE INVENTION
In the most recent quarter century, there has been a major effort to increase fuel economy of automotive vehicles. To achieve an increase in fuel economy, several technical trends have developed. One technical trend is a change from rear wheel drive to front wheel drive vehicles. Front wheel drive vehicles tend to increase fuel economy by placing the weight of the engine over the traction wheels of the vehicle. Another technical trend is to diminish the vehicle's aerodynamic drag. To lower the aerodynamic drag, the hood region of many vehicles has been lowered. The front end of the vehicle is more round or pointed instead of the box front end which was common on many prior vehicles. Additionally, the grill area is typically smaller.
The use of two-stroke cycle internal combustion engines has been proposed to significantly reduce vehicle weight and to further reduce aerodynamic drag by further lowering the hood. Conventional two-stroke internal combustion engines have a very high power-to-weight ratio. Accordingly, use of a two-stroke engine would reduce the overall vehicle weight. Moreover, two-stroke engines have a very high power-to-space ratio as compared with the conventional four stroke engines. Accordingly, the use of two-stroke engines would allow for further lowering of the front hood to further reduce the aerodynamic drag of a vehicle.
Conventional two-stroke engines have been limited in their applications by issues with symmetrical port opening control times and, as a result, short circuit scavenging. To reduce the port opening control time, scavenging pumps are employed to overcome the limitations of scavenging at gage pressure. Limitations in available economic sealing methods effectively limit pump pressure and therefore the volumetric efficiency of the engine. Thermo-efficiency is also limited by the need to keep incoming air dense (cool).
It is desirable to provide a two-stroke internal combustion engine which provides a high scavenge pressure that delivers high density air and also reduces the port opening time.
SUMMARY OF THE INVENTION
To make manifest the above delineated and other manifold desires, the revelation of the present invention is brought forth. In a preferred embodiment, the present invention brings forth a supercharged two-stroke internal combustion engine that has ignition and exhaust valve timing which can be selectively varied independent of the compression stroke of the engine. In a preferred embodiment, the present invention provides a first piston with a head. The first piston has a valved exhaust line intersecting with the first piston head. A second piston fixed with respect to the first piston is provided with a head facing the first piston. The first and second pistons are positionally fixed to a common axis of the vehicle. In like manner, the second piston has a valved exhaust line intersecting with the second piston head. A first sleeve is provided which encircles the first piston. The first sleeve has a closed end generally opposite the first piston head forming a first air intake space with the first piston. A second sleeve is provided which encircles the second piston. In a similar manner, the second piston has a closed end generally opposite the second piston head. The second sleeve forms a second air intake space with the second piston. First and second check valves are respectively provided for allowing flow of air into the first and second intake spaces.
A cylinder is provided which is slidably mounted on the first and second pistons for reciprocal movement thereon. The cylinder is H-shaped having an internal pressure boundary forming a first combustion chamber with the first piston and a second combustion chamber with the second piston. The cylinder has a first peripheral end sealed with the first piston and the first sleeve forming a variable volume induction/compression area in the first intake space. The cylinder also has a second peripheral end, which is sealed with the second piston and with the second sleeve, forming a second variable volume induction/compression area in the second intake space.
The cylinder has a first passage connecting the first intake space with the second combustion chamber when the cylinder is moved adjacent an extreme position towards the first piston to deliver a charge of compressed air to the second combustion chamber. The cylinder has a second passage connecting the second intake space with the first combustion chamber when the cylinder is moved adjacent an extreme position with respect to the second piston to deliver compressed air to the first combustion chamber. In operation, the air fuel mixture within the first combustion chamber is ignited. The cylinder is translated from a position adjacent to the head of the first piston in a direction towards the second piston. The movement of the cylinder towards the second piston causes air to be induced within the first intake space. Simultaneously, air within the second intake space is compressed, as is the charge, which is currently in the second combustion chamber. Exhaust gases from the first combustion chamber are thereafter removed through a valved line in the first piston. Contemporaneously, the charge, which is compressed in the second intake space has transferred via a passage in the cylinder to the first combustion chamber. After being fully compressed, the second combustion chamber is ignited to transfer the cylinder back towards the first piston. Air is induced into the second intake space by the movement of the cylinder. Simultaneously, entrapped air in the first intake space is compressed as is the charge within the first compression area. With the cylinder reaching a point adjacent an extreme position towards the first piston, the exhaust of the second combustion chamber is valved through the second piston. Contemporaneously, a compressed charge is delivered through a separate passage from the first intake space to the second combustion chamber. Thereafter, the charge within the first combustion chamber is fully compressed and the charge is ignited reversing the cylinder and starting a new cycle. In the preferred embodiment, power is delivered from the cylinder via an eccentric connection with a crankshaft. Alternate technology may include electromatic induction and/or pumping a coupling fluid media.
The internal combustion engine of the present invention provides supercharging with a high scavenge pressure which delivers high density air. Port opening time is significantly reduced. Transfer port opening time is also minimized which increases the volumetric efficiency. In a preferred embodiment, the cylinder can be annular in shape so that it may benefit from utilizing existing piston ring sealing technology and formed components. The exhaust valve venting through the fixed pistons enables the possibility of scavenging heat from the exhaust gas during the supercharging process which provides additional thermo-dynamic benefits.
It is a feature of the present invention to provide a two-stroke internal combustion engine wherein the exhaust is valved through the pistons.
Other features of the invention will become more apparent to those skilled in the art upon a reading of the following detailed description and reference to the drawings.
REFERENCES:
patent: 1278571 (1918-09-01), Bell
patent: 1437928 (1922-12-01), Brockway
patent: 2786458 (1957-03-01), Luttrell
patent: 4178885 (1979-12-01), Konther et al.
patent: 4331108 (1982-05-01), Collins
patent: 4425880 (1984-01-01), Rochlus
patent: 5490482 (1996-02-01), Genet
patent: 5692462 (1997-12-01), Hackett
Ford Global Technologies Inc.
Hanze Carlos
McMahon Marguerite
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