摘要 |
A variable compression ratio piston I.C. engine includes a piston (14) with an inner chamber (38) separated from the combustion working chamber (16) by an orifice (g). The orifice is geometrically shaped to restrict transfer of gas from the working chamber (16) to the air chamber (38) by causing a choked flow condition to exist across the orifice when the piston speed exceeds that speed at which the critical pressure ratio occurs across the orifice. This prevents pressure equalization between the working and air chambers (16, 38) at the end of the compression of the charge supplied to the working chamber (16) above a selected engine speed to cause an effective increase in engine compression ratio above such speed. A specific piston structure for carrying out the invention is disclosed. |