Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Patent
1994-08-30
1996-08-06
Marmor, Charles A.
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
74413, 74437, F16H 2130, F02B 4104
Patent
active
055423086
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a crank mechanism communicating motion between a reciprocating piston and a rotary shaft and to its application to machines, including all reciprocating prime movers such as heat engines, steam engines, compressors and expanders, which embody linear to rotary motion in their crank mechanisms and with particular application to internal combustion engines.
Reciprocating piston type prime movers have a slidable piston connected to a crank pin of a crank shaft to compress or expand the gas (or other type of fluid) in order to absorb or create energy or convert energy from one form to another. With the existing type of crank mechanism the crank pin rotates concentrically with the axis of the crank shaft and the performance characteristics are inextricably related to the geometric principles of such a crank shaft configuration. Whilst much has been achieved by science and technology to improve the performance characteristics of such prime movers no attention appears to have been given to improving performance by changing the crank mechanism. The present invention when incorporated in such machines aims at achieving radical performance improvements, for example increased thermal efficiency with internal combustion engines, without discarding all that has been achieved to date.
Accordingly, one aspect of the present invention provides a crank mechanism communicating motion between a reciprocating piston and a rotary shaft, comprising a crank pin having journalled thereon a connecting rod of the piston, and wherein the crank pin has an eccentric motion profile relative to the axis of the rotary shaft, the eccentric motion profile being controlled by a driving connection between a stator and a rotor carrying the crank pin, and wherein rotary motion of the rotor and the rotary shaft is communicated one to the other by a journalled connection between the rotor and an eccentric journal of the rotary shaft.
Another aspect of the invention provides a machine incorporating the afore-described crank mechanism. Where the machine is of the type which converts linear to rotary motion, such as an internal combustion engine, the afore-described rotary shaft is an output shaft to which rotary motion is communicated from the rotor by way of the journalled connection. A particular advantage of the use of the described crank mechanism in an internal combustion engine is that it enables the relationship between the thermodynamic cycle and the output torque to be varied. In a conventional engine they cannot be varied in relation to one another. Where the machine is of the type which converts rotary motion to linear motion, the rotary shaft is an input shaft which communicates rotary motion to the rotor by way of the journalled connection.
In converting linear to rotary motion (and vice versa), the eccentric motion profile of the crank pin can exploit various geometric configurations to improve prime mover performance characteristics. Such geometric configurations can embody various combinations of stator/rotor shapes such as a circle rotating on a circle, a circle rotating on a elliptical/parabolic profile, tri-lobed and quad-lobed profiles in various combinations. Furthermore the relative positions of stator and rotor can be off-set in relation to each other for the further fine tuning of performance aspects. Asymmetric configurations are also capable of being exploited. For construction in which the distance of the driving connections of the rotor and stator are variable relative to the rotary shaft axis, a single piece rotary shaft would be expected to be replaced by at least a two-piece construction accommodating relative radial movement between the rotary shaft and its eccentric journal. As a result the relative motion of the piston to the rotary shaft (conventionally the crank shaft) is therefore radically different from all modern day prime movers enabling significant improvements in performance characteristics of the machine to be achieved.
In one embodiment a geared connection is
REFERENCES:
patent: 2090841 (1937-08-01), Jones
patent: 2946503 (1960-07-01), Thompson
patent: 4044629 (1977-08-01), Clarke
patent: 4236416 (1980-12-01), Barcita
patent: 4336723 (1982-06-01), Barcita
Fenstermacher David
Marmor Charles A.
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