Patent GB-1079127-A (GB)
Title: Rotary piston machines
IPC: F01C19/10
Filed: 1965-12-09
Abstract: 1,079,127. Rotary-piston engines  NSU MOTORENWERKE A.G. and WANKEL G. m. b. H. Dec. 9, 1965 [Dec. 10, 1964], No. 52210/65. Heading F1F. In a rotary-piston machine e. g. an I. C. engine, of the trochoidal n and n + 1 lobe type, leakage of liquid coolant from the interior of the piston 8 is prevented by a pair of flanges on an axialextension 7aof an eccentric 7, on which the piston is mounted in a known manner, and by an annular body 21 attached to the side of the eccentric remote from said extension, outwardly-biased split sealing-rings 19a, 19b being lodged in annular grooves 20a, 20b defined by said flanges and said body, respectively, to effect sealing with respect to axial bores in the corresponding ends of the piston. Leakage of coolant through the grooves 20a, 20b, is prevented owing to the rings being pressed against the axially-innermost sides of the grooves by working fluid that leaks past axial sealing-strips 13 into spaces 15, 16 between the piston and end walls 3, 4 of the housing. The pressure of the working fluid in the spaces 15, 16 is determined by a pressure-relief valve 26 lodged in a passage 25, which is situated in the wall 3 and connected to the inlet side of the machine, said spaces being connected to each other by a passage 27 in the eccentric. Leakage of coolant into the working chambers of the machine when it is idle is prevented by further sealing rings 51 situated in the ends of the piston between the rings 19a, 19b and the strips 13, each ring being pressed against the adjacent end wall of the housing by a wavy leaf-spring 54 and sealed relative to the piston by a rubber ring 52. When the engine is started, the rings 51 are depressed against the action of the springs 54 by the working fluid leaking past the strips 13 so that the fluid can enter the spaces 15, 16. The body 21 is sealed relative to the end wall 4 by a split ring 24b, a similar ring 24a being provided on the shaft 5 adjacent the extension 7a to effect sealing relative to the end wall 3. Leakage of working fluid past the rings 24a, 24b may also serve to determine the pressure in the spaces 15, 16. Each of the rings 19a, 19b may be constituted by a pair of split rings (55, 56), Figs 3 and 4 (not shown), which are attached to each other by a pin (57), gaps (55a, 56a) in the rings being situated in different radial positions. In a modification, Fig. 5 (not shown), each of the rings 19a, 19b is constituted by a pair of split rings (61, 62) having a channel cross-section. In another modification, Fig. 6 (not shown), each of the rings 19a, 19b has a tapering configuration towards a gap (66) therein to render its stiffness uniform, a space (20) in the corresponding groove being partly filled by a crescent-shaped member (64), which is retained by a tooth or projection (65) thereon engaging with the gap (66) and is made of a material e.g. carbon, a light alloy or a synthetic resin, having a relatively low density. Coolant e.g. oil, enters the interior of the piston through passages 17 in the shaft 5 and is ejected through the wall 4 in a region 18. The engine may comprise two pistons (37, 38), Fig. 2 (not shown), which are cooled and sealed in a manner generally similar to that shown in Fig. 1, the valve 26 being lodged in a central wall (35) and connected to the spaces (39, 40) between the pistons and the corresponding end walls (33, 34) of the housing by oblique passages (47) in the shaft and/or axially-orientated pipes (45) in the pistons. The passages (47) are rendered oblique to prevent accumulation of carbon deposits therein.