Internal-combustion engines – Multiple piston – common nonrestrictive combustion chamber – Four-cycle
Reexamination Certificate
1999-07-28
2001-03-20
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Multiple piston, common nonrestrictive combustion chamber
Four-cycle
Reexamination Certificate
active
06202605
ABSTRACT:
The present invention relates to an arrangement in a two cycle combustion engine with internal combustion, comprising a plurality of engine cylinders, which are arranged in an annular series around a common central drive shaft and which have cylinder axes running parallel to the drive shaft, each cylinder including a pair of pistons movable towards and away from each other and for each pair of pistons a common, intermediate work chamber, while each piston is equipped with its axially movable piston rod, the free outer end of which forms via a support roller a support against its curve-shaped, that is to say “sine”-like curve shaped, cam guide device, which is arranged at each of opposite ends of the cylinder and which guides movements of the piston relative to the associated cylinder.
Geometric Considerations of the Afore-mentioned Motor System
When the drive shaft of the engine is moved in a circular path, the oscillation movements of the engine pistons can correspondingly according to the afore-mentioned motor system be observed graphically as to time in a sine-shaped curve path according to
Formula 1: y=sine x.
From DE 43 35 515 it is priorly known two stroke engines of the art described initially, having a single cylinder provided with two opposed pistons and having conventional crank shafts and conventional crank arms. Formel 1 is also relating to each crank shaft of such engine. In order to optimise the combustion in such engine it is suggested mutually displaced piston movement phases for the two opposed pistons of the cylinder.
By the use of a sine curve-shaped cam guide device and respectively by the use of conventional crank shafts the backwards and forwards piston movements of the individual pistons of the cylinders can in fact be controlled, so that the oscillation movements of the pistons synchronously coincide with the rotational movement of the drive shaft. Over the course of a complete rotation of the drive shaft, the pistons are moved backwards and forwards in a forcibly controlled manner in one or more working strokes, which are accurately synchronised with the rotational movement of the drive shaft. In other words the rotational movement of the cam guide device and the drive shaft will be directly connected to the oscillation movement of the pistons, and vice-versa.
The backwards and forwards movements of the pistons will correspondingly constitute a multiple of the rotary movement of the drive shaft with each 360° rotation of the drive shaft. In other words each piston will move backwards and forwards in the associated cylinder a total number of times, that is to say from one to for example four times with each 360° rotation of the drive shaft.
Owing to the cam guide device, which controls the oscillating movements of the pistons in an associated cylinder, being rotated synchronously with the drive shaft of the engine, the oscillation movements of the pistons can consequently be controlled by designing the cam guide device with a sine-shaped curve contour, so that these conform to the rotational movement of the drive shaft.
“Sine”-like Concept.
When the term “sine”-like is employed herein in connection with expressions, such as “sine”-like concept, “sine”-like curve, “sine”-like plane, etc.), a curve contour is expressed which does not constitute a mathematical sine contour according to the formula 1 above, but on the other hand expresses a varying curve contour, which only generally resembles the path of a mathematical sine contour. By the term “sine”-like contour there shall be designated generally herein a contour which is like but differs from a sine contour.
According to the invention the aim is, in certain constructional connections, with regard to designing the cam guide device with a particular curve contour which in different ways deviates from a mathematical sine contour.
Generally this means further, according to the invention, that by designing the cam guide device with a specially fashioned “sine”-like contour, which deviates from a conventionally known sine contour, the piston movements can be adapted in a corresponding manner to additional engine functions relative to the rotational movement of the drive shaft and relative to previously proposed solutions.
According to the invention the general aim is to design the cam guide device so that there is a possibility of achieving optimum operating conditions for pistons of the motor, based on a simple and operatively reliable operating sequence.
When one speaks herein about “sine”-like plane, there is meant the local part of the cam guide device, which has a “sine”-like curve contour. In practice the individual cam guide device has a 360° arcuate contour, which corresponds to a multiple of such said “sine”-like planes.
Combustion engines, where the axial movement of the pistons is individually controlled by a cam guide device via associated “sine”-like planes, function generally according to the so-called “sine”-like concept, which has been known for a number of years.
Originally the “sine”-like plane has had a contour, which resembles to a large degree the mathematical sine contour, that is to say with mutually symmetrical and uniformly curved curve portions.
According to the patent literature, curve contours have gradually been proposed which in different ways deviate from the mathematical sine contour. This is also typical of the curve-contour of the cam guide devices according to the present invention.
According to the “sine”-like concept the mechanical energy is transferred from the single piston to the common drive shaft of the engine cylinder, that is to say via a support roller of an associated piston rod to the “sine”-like plane of the cam guide device. The “sine”-like planes, which separately control the oscillation movements of the pistons, transfer during the oscillation movements of the pistons:
partly kinetic energy from the expansion stroke of the pistons via the “sine”-like plane to the drive shaft, so as to subject the drive shaft to a rotary movement with associated torque, and
partly torsional moments from the drive shaft via the “sine”-like plane back to the pistons, so as to subject the pistons to the necessary kinetic energy during the compression stroke.
In combustion engines of the kind indicated by way of introduction the pistons are moved axially backwards and forwards in associated cylinders, almost exclusively in rectilinear movements axially along the drive shaft, while the piston rods and associated support rollers are moved in corresponding rectilinear movements and consequently transfer motive forces from the support rollers to the associated “sine”-like plane in an axial direction along the drive shaft.
The transfer of the motive forces from the pistons via support rollers to the “sine”-like plane, which is designed in driving connection with the drive shaft, and return forces which are transferred in the opposite direction from the drive shaft to the pistons via the “sine”-like plane, occur on curve portions which extend obliquely of the rotational plane of the drive shaft. In other words motive forces are transferred between the support rollers and the “sine”-like plane during displacement of the support rollers axially along the drive shaft. In the dead points between the backwards and forwards going piston stroke there occurs however no transfer of motive forces, this despite that in the one dead point, that is to say at the close of the compression stroke and after ignition of injected fuel, significant motive forces arise between the pistons going towards and away from each other.
With the present invention the particular aim is to utilize the last-mentioned condition in connection with a special design of the cam guide device, so that in said dead point a hitherto disregarded possibility can be achieved for controlling the combustion process of the engine in an especially favorable manner.
Comparison of Four Stroke and Two Stroke Engines.
In a four stroke combustion engine the piston rods transfer their motive forces via the “sine”-like plane in the
Ali Hyder
Carella Byrne Bain Gilfillan Cecchi & Olstein
Hand Francis C.
Wolfe Willis R.
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