The 300 W class low temperature degree difference Stirling engine is a gamma type Stirling engine and is composed to a displacer, power piston and a heat exchanger. The displacer piston is foamed polyurethane made in order to keep light-weight, and the power piston is aluminum made. Scotch-yoke mechanism is used for driving of a power piston, a side thrust of a piston ring is reduced by this, and then an engine is miniaturized. In a heat exchanger, from upper part, cooler, regenerator, heater is arranged around a displacer cylinder. The heater and the cooler use Finn tubes in order to use hot springs, warm drainage of a plant, as heat-source. The regenerator is a form to pile up a metal net. In order to seal up between engine inside and buffer space, an one-way type piston ring and 1-way type shaft seal is used. By using these devices, the minimum pressure in the engine raises an even buffer pressure level, and it gets possible to increase output of the engine. With this engine, a driving mechanism is covered and sealed up with a shell, and it is possible to add a buffer pressure.
Engine type | Gamma type | |
---|---|---|
Power piston | Bore | 400mm |
Stroke | 100, 150, 200mm | |
Material | Alminium | |
Drive Mechanism | Sckoch Yoke | |
Displacer Piston | Bore | 800mm |
Stroke | 80mm | |
Material | Urethane Form | |
Drive Mechanism | Simple Crank | |
Compression Ratio | 1.271 |
With 300 W class low temperature difference Stirling engine, since hot springs or warm drainage of a plant etc. is assumed as heat-source, a heater and cooler use a closs flow type heat exchanger using Finn tube. A regenerator becomes a formality to pile a metal net. From bottom, with an order of a heater regenerator cooler, these are arranged around a displacer cylinder. For a specification of each heat exchanger as follows.
Heater | Volume | 14866.3 cc |
---|---|---|
Type | Fin Tube | |
Material | Copper | |
Number of Tubes | 8 | |
Pitch of Fin | 3.2 mm | |
Cooler | Volume | 14866.3 cc |
Type | Fin Tube | |
Material | Copper | |
Number of Tubes | 8 | |
Pitch of Fin | 3.2 mm | |
Regenerator | Volume | 2424.6 cc |
Type | Wire Matrix Laminated | |
Material | Brass Wire Cloth | |
Mesh | 50 |
With 300 W class low temperature degree difference Stirling engine, in order to reduce friction of this piston ring, a peculiar Scotch Yoke mechanism is used for driving of a power piston. With this mechanism, linear bearing is arranged rectangularly on Yoke of L shape. A movement of a power piston becomes a sinusoidary straight-line motion by using this mechanism, and a side thrust is greatly reduced and decreased drastically for friction loss of an engine.
With piston ring, One-way type piston ring and, rider ring (that is used in order to receive a side thrust) are used. By using the one-way type piston ring, raise the minimum pressure inside an engine even around a buffer pressure and can increase output of an engine.
An important role of a displacer piston is thermal insulation of high-temperature space and low temperature space of an engine and is to make a heat exchanger pass through working gas well. With the displacer of 300 W class low temperature difference Stirling engine for this reason, a simplified piston ring is installed. Working gas, leak from space to space as not passing through a heat exchanger, decreases by this ring. Foamed polyurethane of the material contributes greatly in thermal insulation of both space also.