Moveable regenerator for stirling engines

Details Moveable regenerator for stirling engines Moveable regenerator for stirling engines

2002-05-03

2004-03-09

Richter, Sheldon J. (Department: 3748)

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...

C060S519000, C060S520000, C060S526000, C062S006000

Reexamination Certificate

active

06701708

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to engines and, in particular, to Stirling cycle engines.
2. Description of the Related Art
Stirling cycle engines have a theoretical thermodynamic efficiency that is much higher than internal combustion engines. However, Stirling cycle engines are not as widely used as internal combustion engines because Stirling cycle engines typically require complicated hardware, which results in very low power-to-weight and power-to-volume ratios.
For example, a typical Stirling cycle engine includes an enclosed chamber, a displacer piston, a power piston and a crankshaft. The displacer piston is positioned within the enclosed chamber and is connected to the crankshaft by a shaft, which extends through the walls of the chamber. The power piston is also connected to the crankshaft and has one end that is in communication with the interior of the chamber. With respect to the crankshaft, the displacer piston and the power piston are typically 90 degrees out of phase with each other.
In operation, the displacer piston moves working fluid from a cold side of the chamber to a hot side of the chamber. This causes the working fluid to expand. This expansion pushes the power piston, thereby rotating the crankshaft. As the crankshaft rotates, the displacer piston moves the working fluid to the cold side of the chamber. This causes the working fluid to contract, pulling the piston down. As the piston moves back down, the crankshaft rotates and the displacer piston moves the working fluid to the hot side of the chamber, thereby completing the cycle.
There is, therefore, a need for an improved design for a Stirling cycle engine that minimizes at least some of the disadvantages described above.
SUMMARY OF THE INVENTION
The present invention provides for several novel Stirling cycle engine designs, which provide for increased efficiency and better power to volume ratios than conventional designs. In one preferred embodiment, the engine comprises a sealed engine block that defines a cylindrical chamber. A rotary displacer is suitably journalled for rotation within the engine block. A displacer drive motor rotates the rotary displacer and is controlled by a microprocessor. Working fluid in the chamber is in communication with a rolling sock seal piston, which, in turn, is coupled to a generator. For alternately heating and cooling the working fluid, a heat source is located on one side of the sealed chamber and a heat sink is located on another side of the sealed chamber. In modified embodiments, the rotary displacer is counter balanced and/or shaped to reduce aerodynamic drag.
In another embodiment, a Stirling engine comprises a sealed engine block that defines a cylindrical chamber, which encloses a working fluid. The engine block including a first quadrant, a second quadrant, a third quadrant and a fourth quadrant. A rotary displacer is suitably journalled for rotation within the engine block. A displacer drive motor rotates the rotary displacer and is controlled by a microprocessor. Working fluid in the chamber is in communication with a piston. A heat source is configured to heat the first and third quadrants, which oppose each other. A heat sink is configured to cool the second and fourth quadrants, which oppose each other. The rotary displacer moves between a first position wherein most of the working fluid is the second and forth quadrants and a second position wherein most of the working fluid is in the first and third quadrants.
In yet another embodiment, a Stirling engine comprises a sealed engine block that defines a generally triangular chamber, which encloses a working fluid. The engine block comprises a hot side, a cold side and a base. A displacer is suitably journalled for pivotal movement within the engine block. A displacer drive motor moves the displacer in an oscillating arc shaped motion and is controlled by a microprocessor. A heat source is configured to heat the hot side of the engine block and a heat sink is configured to cool the cold side of the engine block. The displacer is moveable between a first position wherein most of the working fluid is near the hot side of the engine block and a second position wherein most of the working fluid is near the cold side of the engine block.
In still yet another embodiment, a Stirling engine comprises a sealed engine block, which encloses a working fluid. The engine block comprises a cylindrical inner member and a coaxial cylindrical outer member. A heat source and a heat sink are configured to keep the inner member and the outer member at different temperatures. A displacer is positioned within the chamber and is configured to move between a first position wherein most of the working fluid is near the outer member and a second position wherein most of the working fluid is near the inner member.
In another embodiment, a Stirling engine comprises a sealed engine block, which encloses a working fluid. The engine block defines a working fluid space, a hot path and a cold path. The hot path is connected to the working fluid space at a hot inlet and a hot outlet. The hot path includes a hot inlet valve and a hot outlet valve. The cold path is connected to the working fluid space at a cold inlet and a cold outlet. The cold path includes cold inlet valve and a cold outlet valve. The engine further including a working fluid circulator for circulating the working fluid within the engine. A heat source and a heat sink are configured to keep the hot path and the cold path at different temperatures. A control system is configured to alternately open and close the hot path and the cold path such that the working fluid is alternately circulated through a first past that is defined, at least in part, by the hot path and the working fluid space and a second path that is defined, at least in part, by the cold path and the working fluid space.
In another embodiment, a Stirling cycle engine comprises a substantially sealed engine block that defines a working fluid space, a hot path and a cold path. A heat source and a heat sink are configured to keep the hot path and the cold path at different temperatures. The engine includes a valve chamber that is communication with the working fluid space, the hot path and the cold path. A valve is moveably positioned within the valve chamber between at least a first position and a second position. The valve defines a passage that, in the first position, places the working fluid space in communication with the hot path and, in the second position, places the working fluid space in communication with the cold path. A regenerator positioned within the passage.
In another embodiment, a method of operating a Stirling cycle engine having a substantially sealed engine block that defines a working fluid space, a hot path and a cold path, the method comprises passing a working fluid through the hot path, passing the working fluid into the working space, passing the fluid through a regenerator and into the cold path, passing the fluid through the cold path, moving the regenerator such that it is in communication with the hot path and the working space, passing the fluid into the working space; and passing the fluid through the regenerator into the hot path.
In another embodiment, a Stirling cycle engine comprises a substantially sealed engine block that defines a working fluid space, a hot path and a cold path. A heat source and a heat sink are configured to keep the hot path and the cold path at different temperatures. A valve chamber is in communication with the working fluid space, the hot path and the cold path. The engine further comprises a regenerator and means for moving the regenerator so as to alternately direct working fluid from the working fluid space to the hot path and the cold path.


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patent: 5555729 (1996-09-01), Momose et al.
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patent: 5611201 (1997-03-01), Houtman
patent: 5638684 (1997-06-01), Siegel et al.
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