Power plants – Motor operated by expansion and/or contraction of a unit of... – Unit of mass is a gas which is heated or cooled in one of a...
Patent
1986-12-29
1989-03-28
Ostrager, Allen M.
Power plants
Motor operated by expansion and/or contraction of a unit of...
Unit of mass is a gas which is heated or cooled in one of a...
F02G 104
Patent
active
048152919
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and an arrangement in heat engines, more particularly heat engines of the free-piston type intended for internal or external supply of heat by continuous or intermittent combustion or, as far as the external heat supply is concerned, by heat sources of the type heat accumulator, isotopic heat, solar power or the like.
Heat engines of the piston type may be divided, with regard to their utilisation of the mechanical effect generated, into on the one hand kinematic engines designed with crank and/or link operated mechanisms adapted to produce a mechanical effect on a shaft and, on the other hand, free-piston engines generating a useful effect in the form of a gaseous or hydraulic pressure, electric current or other form of energy directly by reciprocating piston movement.
The kinematic piston engines which today are the dominant piston type heat engines, are highly advantageous in that the power generating forces can be controlled in a relatively optimal manner, resulting in a favourable thermal efficiency and power density. This applies to both internal combustion engines of the Otto or Diesel type and to piston engines with external heat supply of the hot gas type with Stirling or Ericsson cycle, or of the Rankine type, regardless of whether heat is supplied by continuous or intermittent combustion, or in some other manner. The shortcomings of kinematic piston engines are well known and reside in the relatively high cost of the rotating mechanical power transmission, the necessity of a developed lubricating system with circulating lubricating oil, and the heavy friction losses reducing engine efficiency.
Free-piston engines therefore have been the subject of many inventions and improvements, but never have succeeded in finding a more extensive practical use. The difficulties encountered in developing free-piston type engines have largely been attributable to defective piston guide means, low useful effect and reduced reliability after the engine has been operating for some time when wear has changed the balance of the piston forces.
For this reason, it has so far not been possible to utilise to any greater extent the inherent simplicity of the free-piston engines which is due to the fact that the piston or pistons, operated by the pressure generating effect of the thermodynamic process, are able to generate directly, without the intermediary of any rotating mechanisms that may produce losses, a useful effect in the form of electric current, hydraulic power etc. Free-piston engine constructions therefore have been characterised so far by moderate efficiency, low power density, high cost per unit of power, vibrations during operation, and unreliability.
It therefore is the object of the present invention to design free-piston engines in such a manner that the advantages of simplicity, low production cost and robustness are maintained, while at the same time the advantages of an exact and practically optimal piston movement are achieved, whereby the good qualities of the kinematic piston engine can be realised.
To achieve this object, the useful effect from the piston is received directly, without the intermediary of crank-operated rotating mechanisms, in an effect-receiving device in the form of, for example, a linear electrical generator which is activated by the piston movement in a magnetic field within the cylinder or, inversely, the piston itself generates within the cylinder a movable magnetic field which activates electrical windings within the cylinder, such that an electric current is obtained. Alternatively, the piston itself may generate gas forces or hydraulic forces, or directly operate another piston generating gas or hydraulic forces in such a manner that a useful effect can be obtained from the reciprocating linear movement of the piston or pistons.
In one practical application, the working piston of the engine is connected directly with another piston or an armature in a linear electrical generator, the effect still being transmitted solely by a reci
REFERENCES:
patent: 3552120 (1969-03-01), Beale
patent: 4188791 (1980-02-01), Mulder
patent: 4511805 (1985-04-01), Boy-Marcotte et al.
patent: 4642547 (1987-02-01), Redlich
Ostrager Allen M.
Stig G. Carlqvist Motor Consultant (C.M.C.)
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