GB1068209A - Improvements relating to rotary piston internal combustion engines - Google Patents

Abstract

1,068,209. Rotary-piston L C. engines. ROLLS-ROYCE Ltd. Oct. 12, 1965, No. 43201/65. Heading F1F. A rotary-piston I. C. engine comprises in a common casing 10, Fig. 1, a first unit having a three-sided planetary rotatable piston 11 sealingly engaging an inner peripheral wall 14 of doublelobed epitrochoidal profile, a second unit having a two-sided planetary rotatable piston 12 sealingly engaging an inner peripheral wall 22 of singlelobed epitrochoidal profile and a third unit also having a two-sided planetary rotatable piston 13 sealingly engaging an inner peripheral wall 23 of single-lobed epitrochoidal profile. The units are arranged co-planar in the casing with parallel shafts 16, 27, 28 on which the pistons 11, 12, 13 are eccentrically mounted with the pistons interconnected by gearing 17, 32, 33, 34 to drive a common output shaft 35. Air is admitted to the second unit through a port 53 and on rotation of the piston 12 is compressed between the pistons 11, 12 and their respective walls. It is then transferred through a duct 36 which is kept as short as possible to the first unit wherein it is further compressed by rotation of the piston 11. On completion of compression, where a side of the piston 11 is opposite to fuel-injectors 20 and spark-plugs 21, fuel is injected into the first unit and the gaseous mixture is ignited and expanded until the leading edge of the said side of the piston uncovers an exhaust port 50. The gaseous mixture is then transferred through a duct 37 which also is kept as short as possible to the third unit wherein further expansion takes place between the pistons 11, 13 and their respective walls until the opening of a port 54 through which the spent gases are finally expelled. The volumetric compression and expansion ratios are preferably substantially the same in which case the second and third units are identical. Alternatively the expansion ratio may be greater, e.g., 25 to 1, than the compression ratio, e.g., 18 to 1, so that the gases are expanded substantially to atmospheric pressure. The eccentrics on which the pistons are mounted are preferably positioned with respect to each other so that the piston 12 leads the piston 11 by 30‹ and the piston 13 lags the piston 11 by 30‹ with the ports 49.... 54 positioned accordingly. The engine achieves high compression and expansion ratios whilst still maintaining a compact and efficient combustion chamber which in part is formed in turn by recesses 17 on the sides of the threesided piston 11.