초록 ▼

A piston ring and piston assembly designed for operation with the piston skirt fully flooded with oil and with the piston rings operating as fully hydrodynamic sliders is disclosed. Geometries of rings and piston skirt are arranged to conform elastically to the real out-of-round deformations of cyli

A piston ring and piston assembly designed for operation with the piston skirt fully flooded with oil and with the piston rings operating as fully hydrodynamic sliders is disclosed. Geometries of rings and piston skirt are arranged to conform elastically to the real out-of-round deformations of cylinder walls in such a fashion as to maximize the advantages of full film lubrication physics. The rings are loaded in circumferential compression and are flexible. This elastic configuration makes the rings conform instantaneously to cylinder wall out-of-round to a scale of microinches. This conformability is required to maintain oil control (zero oil pumping to the top of the cylinder wall) with fully hydrodynamic conditions between the rings and the cylinder wall. The piston has a piston skirt which is flexible enough to conform to cylinder wall out-of-round and maximize squeeze film effects. The piston skirt is arranged to superimpose squeeze film and pivoted pad slider physics. The piston is equipped with a heat piped internal heat transfer structure which maintains the piston in a near isothermal condition. The piston skirts are nearly isothermal. This controls expansion for improved hydrodynamic geometry. The great majority of heat transfer from the piston crown to the cylinder passes through the piston skirt oil film to the cylinder wall. The assembly utilizes component deformations to maximize hydrodynamic and squeeze film lubrication effects to minimize engine friction and wear.

대표청구항 ▼

In a machine having a piston which reciprocates in a cylinder and mounts a wrist pin extending perpendicularly to the central axis of the cylinder, a connecting rod is operatively connected to the wrist pin and with its other end connected to an engine crankshaft by suitable bearing means, said pist

In a machine having a piston which reciprocates in a cylinder and mounts a wrist pin extending perpendicularly to the central axis of the cylinder, a connecting rod is operatively connected to the wrist pin and with its other end connected to an engine crankshaft by suitable bearing means, said piston having a top portion mounting a means for sealing the piston with respect to the cylinder wall as it reciprocates therein, a piston top with a boss structure depending therefrom, said boss structure having a transverse hole adapted to mount the wrist pin, a skirt assembly positioned below the top portion and comprising two arcuate thrust bearing skirts supported by the aforesaid boss structure, each arcuate thrust bearing skirt comprising, a cylindrical segment flexible in bending with respect to cylinder wall distortion and constrained against circumferential compression forces at its vertical edges by rigid connection to the wrist pin boss, the top of each segment being mechanically spaced from the piston top so that said piston top does not constrain deformation of said segments, the radius of the outer cylindrical surface of each segment being slightly smaller than that of the cylinder wall in which the piston reciprocates, whereby the forces transmitted from the wrist pin to the cylinder wall are borne by the cylindrical segment thrust bearing skirts in circumferential compression so that said skirts conform to local variation in cylinder distortion and local oil film pressures to provide a relatively even radial force on the cylinder wall for the area covered by the thrust bearing skirt faces to maximize the effectiveness of said skirts as full film bearings acting on the cylinder wall, the cylindrical thrust bearing skirts being vertically centered with respect to the central axis of the wrist pin so that the skirts act as pivoted pad bearings pivoting about said wrist pin center axis as the piston reciprocates, each cylindrical thrust bearing skirt having a mid portion with its outer surface cylindrical and centered about the wrist pin center axis, the remaining portions above and below each mid portion being slightly barrel shaped radially inwardly to function as sled runners with respect to said cylindrical mid portion surfaces whereby said barrel spaced portions catch piston rock and assure proper convergent pivoting of said cylindrical skirts with respect to the cylinder wall as the piston reciprocates, wherein said piston is adapted with flexible fully hydrodynamic piston rings, wherein lubrication means are provided so that said arcuate thrust bearing skirts are fully flooded with oil as they interact with the cylinder wall, and wherein heat pipe cooling means are provided to maintain said arcuate skirts in a nearly isothermal condition at a temperature close to the temperature of said piston crowns.