GB846995A - Improvements in or relating to trunk piston engines - Google Patents

Abstract

846,995. Balancing pistons. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 15, 1959 [April 18, 1958], No. 12345/58. Class 122 (1). A trunk piston 1 reciprocating in a cylinder of an engine and subjected to transverse forces comprises piston-rings 4 mounted above and below the gudgeon-pin 5 and so formed as to serve to entrap in the space between the rings a volume of fluid which effects viscous damping of the said forces, and means 2, 3 for substantially preventing the leakage of fluid from the space. As shown, the two rings 4 are provided to define the upper and lower boundaries of the space and are each tapered away from the latter so that, in operation, oil is collected and trapped in the space by the reciprocation of the piston. In a modification, two vertical barriers 8 in line with the gudgeon-pin axis and connected with the upper and lower boundaries are provided so as to divide the space into two parts in order to form a restriction for the oil which, upon transverse movement of the piston during reciprocation, is forced from one part to the other.. In he atrrangement shown, the two tapered rings 4 are combined with the barriers 8 which are urged into contact with the cylinder wall by springs 9 located in bushes 6 mounted in the ends of a hollow gudgeon-pin 5. The springs act against members 7 which are provided with oil-holes 10, 11 communicating through holes 12 in the bush 6 with grooves 13 formed in the surface of the piston within the space between the rings 4; pressurized oil is fed through a bore in the connecting-rod and hollow gudgeon through the oil-holes into the space. The radial pressure on the barrier members 8 may be effected, if desired, by the oil pressure alone.