Internal-combustion engines – Four-cycle – Single revolution
Patent
1992-08-05
1994-01-11
Kamen, Noah P.
Internal-combustion engines
Four-cycle
Single revolution
F02B 7500
Patent
active
052771555
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a system for obtaining a complete cycle with a single rotation of the crankshaft in a four-stroke internal combustion engine.
BACKGROUND ART
In internal combustion engines, particularly in four-stroke engines, the cycle is carried out in two rotations of the crankshaft. This uses the traditional link arm-crank system, which requires a full descent and return of the piston for a full turn to occur with a single rotation of the crankshaft. This situation leads to irregularities in the transferred torque and to stray inertial forces. These actions disrupt the balance of the engine.
A 0.5 reduction in ratio should be introduced in the transmission from the crankshaft rotation to the cam-shafts so as to assure proper distribution. This process, however, complicates engine kinematics, thus weakening the engine itself.
For a pre-determined number of cylinders, the power supplied is limited by the maximum inertial forces which can be supported by the pistons. Moreover, the effort to raise the power-to-weight ratio by increasing crankshaft rotation speed necessitates the addition of a substantial reduction mechanism, taking into account rotation speeds to be transferred to the wheels. This leads to rapid cylinder and piston wear.
Rapid engines require close and constant supervision of the number of crankshaft rotations. It must be taken into account that, as described above, during high speeds of operation, the link arm and pistons are quite close to the point of breaking down; high output is obtained at this cost.
A mechanism allowing a four-stroke engine to perform a cycle in a single rotation of the crankshaft is already known (French Patent Request No. 2,622,251). The aim of this mechanism is to increase the output of internal combustion engines and to simplify their construction. Its principal features are its orbital link arm, mounted on the oblique crankpin of a crankshaft, attached to the piston with an auxiliary link arm. Operation of this system requires replacing the classical rotation pin, joining the piston to the link arm with a swivel joint allowing orbital displacement of the auxiliary link arm. This complicates the structure, weakens the bond between the link arm and the piston and generates considerable cyclic end thrusting on the crankshaft. This can cause vibrations which are detrimental to the performance of the crankshaft bearings.
The object of this invention is to overcome these disadvantages. This invention, in its present form, resolves the problem of creating a new system for transforming linear piston displacement in an internal combustion engine to shaft rotation, thus allowing the association of two descents and returns of a piston with a single rotation of the shaft.
SUMMARY OF THE INVENTION
On a four-stroke internal combustion engine, the system allows for the achievement of a cycle with a single rotation of the crankshaft. On a two-stroke engine, the achievement of two cycles on a single rotation depends principally on a crank. In such an engine, the crankshaft is free to rotate in the slide block of a runner, pivoting on a pin that is rigidly attached to the bottom of the engine casing, or to a crossmember mounted on the engine block and pivoting on the end of the link arm, itself pivoting on the piston pin, moving in the cylinder along a predetermined stroke C.
For a fixed crank radius R, the length X of the link arm and the length Y of the runner are determined so that when the piston is in its lowest position, the crank forms a right angle with the pivoting runner. The distance D of the pivot pin of the runner with respect to the cylinder base is adjustable. The slide block is joined to the pivoting runner with a groove.
The advantages of the present invention are essentially that it permits a four-stroke internal combustion engine to achieve completion of the cycle corresponding to a single rotation of the crankshaft. This makes high power-to-mass ratios possible with rotation speeds still remaining much lower than maximum speeds
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