Advanced science.  Applied technology.


Variable Compression Piston: 5,331,928


An engine having a variable piston capable of adjusting an engine's compression ratio while cranking or operating throughout an engine's speed/load range. Control may be obtained through varying the volume of lubricating fluid supplied to an inertia operated pump/accumulator device located in each multi-element piston. Fluid is supplied to said pump/accumulator device by means of a low pressure jet directed into an opening in the accumulator. No direct plumbing connection is required between the fluid source and the pump/accumulator device. Each piston includes an inner element conventionally mounted on a connecting rod and an outer element slidably mounted above and around said inner element. A chamber is formed between the upper surface of said inner element and the inside top surface of said outer element. Supplying a fluid into this cavity extends the upper portion of the piston, raising the engine compression ratio. Said chamber is constructed with a small orifice draining to a second smaller cavity within the multi-element piston and used to modify relative motions. When fluid supply is less than said drain rate, the piston upper portion will retract and compression ratios will decrease. When fluid supply exceeds the drain rate, compression ratios increase. The system also allows for remote control of compression ratio through variation in the volume of oil supplied through supply jets. The system also insured a steady supply of fluid for piston cooling.

Patent Number: 
Date Of Issue: 

Charles D. Wood