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Rolling piston pumps fluids
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01/04/2007
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A novel compressor-expander, designed to make refrigeration systems more efficient, is efficient, simple and lubricated by the working fluid, writes Tom Shelley. It also appears to be a design that could be manufactured at low cost.
Apart from its obvious interest to the developers of air-conditioning systems for the automotive industry, it also appears to have potential as a pump for, say, hydraulic fluids, oil, or engine coolant systems.
Our illustrations show the working principle of the mechanism that combines a hingeing vane and an eccentrically mounted rolling piston. The piston mains its orientation and point of contact with the hingeing vane as it is rolled round the inside of the cylinder by a drive shaft.
Designed by Ron Driver of EA Technical Services in the UK, the prototype machine has been designed to compress R134A refrigerant. Testing has been carried out at the University of Ulster which has specialist expertise in refrigeration. This includes a 100-hour test using only refrigerant as the lubricant.
An interesting way of eliminating manufacturing tolerances has been applied to the machine. Polymer ‘seals’ have been installed in slots on the roller element. During the first few rotations, some of the polymer wears away ensuring an excellent seal.
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Author
Tom Shelley
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