A steel piston (1) for a combustion engine, having an upper part in which a ring section (7) with at least one ring groove (8) is arranged, wherein the upper part is adjoined by a lower part that has two opposing skirt wall sections (2), wherein the two skirt wall sections (2) are connected via two mutually opposite case walls (3), wherein a pin bore (4) surrounded by a piston boss (6) is provided in each case wall (3). In one example, there is at least one aperture (14) or at least one recess in the case wall (3) in the region between the piston boss (6) and the skirt wall section (2).

The present invention relates to pistons (10) for use in internal combustion engines, having: a piston crown (12) which is adjoined by a piston skirt (14), wherein the piston skirt (14) has surfaces (18) which abut the cylinder wall during use of the piston, wherein the surfaces (16) have one or more friction-reducing coatings (18) and wherein depressions (20) are provided in the coating, which are arranged such that the spacing S between each two adjacent depressions (20) along the axial direction (A) of the piston and the width L of the depressions (20) along the axial direction (A) of the piston satisfy the formula S>2L.

A cast piston for an internal combustion engine is made of an iron-based material and has windows in at least one side wall carrying a piston pin boss. The windows are asymmetric relative to one another on the side of the skirt walls.

In an engine piston assembly of the present invention, a piston structure, together with a piston ring set matched to the piston structure and an inner wall of a cylinder bore body, forms a crevice passage having at least two annular expansion chambers and also having a function of multistage throttling and expansion. The engine piston assembly of the present invention can not only greatly and effectively reduce the intra-cylinder carbon deposition and the hydrocarbon emissions in the exhaust gas emissions of the engine, but also significantly improve the engine efficiency and the overall performance of the engine, so that the present invention is suitable for wide applications.

A piston in which a solid lubricant resin layer made of a resin containing a solid lubricant is formed at a skirt portion. A guide groove absent area where no guide groove is formed, which is provided in a predetermined range of the solid lubricant resin layer at a center portion in a width direction. The guide grooves directing from the both ends in the width direction of the guide groove absent area to both ends in the width direction of the skirt portion. The end portions of the guide grooves extended to end edges of the solid lubricant resin layer to form open ends. The solid lubricant resin layer and the guide grooves are formed at least at a thrust side skirt portion. The guide grooves are formed in a shape inclined upward from the guide groove absent area toward the end edges of the solid lubricant resin layer.

A piston includes: a piston head; and a piston skirt connected to the piston head, wherein the piston skirt includes wall portions protruding outward from a surface of the piston skirt, the wall portions adjacent to each other in a circumferential direction of the piston skirt are inclined in directions opposite to each other with respect to a direction of movement of the piston in a bore for the piston, and define a tapered portion, and the tapered portions are spaced away from each other in the circumferential direction of the piston skirt.

A piston includes: a piston head; and a piston skirt connected to the piston head, wherein the piston skirt includes wall portions protruding outward from a surface of the piston skirt, the wall portions adjacent to each other in a circumferential direction of the piston skirt are inclined in directions opposite to each other with respect to a direction of movement of the piston in a bore for the piston, and define a tapered portion, and the tapered portions are spaced away from each other in the circumferential direction of the piston skirt.

An enhanced piston for improving the efficiency of an internal combustion engine has a cylinder with a combustion chamber and a lower cylinder portion. A cylinder head is disposed on the cylinder. An enhanced piston is moveably disposed within the cylinder and is connected to a piston rod. The enhanced piston has a piston cavity. There is an upper piston valve connected to an upper piston valve rod. The upper piston valve is disposed within the piston cavity wherein the upper piston valve selectively seals said piston cavity from the combustion chamber. A piston cavity port is disposed on a bottom portion of the piston cavity and is selectively opened and closed with a lower piston valve. The lower piston valve seals the piston cavity port from the lower cylinder portion. This way the gases are selectively sealed in the piston cavity under pressure until released in the combustion chamber.

A piston for an internal combustion engine has a plurality of recesses formed in a skirt including an upper, a lower, and a central portion. The recesses in the upper portion close to an upper boundary of the central portion have lower ends located upwardly at a given distance away from the upper boundary. The recesses in the central portion close to the upper boundary have upper ends located downwardly at the given distance away from the upper boundary. The recesses in the lower portion close to the lower boundary have upper ends located downwardly at the given distance away from the lower boundary. The recesses in the central portion closer to the lower boundary have lower ends located upwardly at the given distance away from the lower boundary. This enhances lubrication between the piston and an inner wall of a cylinder bore and reduces a friction loss of the piston.

An enhanced piston for improving the efficiency of an internal combustion engine has a cylinder with a combustion chamber and a lower cylinder portion. A cylinder head is disposed on the cylinder. An enhanced piston is moveably disposed within the cylinder and is connected to a piston rod. The enhanced piston has a piston cavity. There is an upper piston valve connected to an upper piston valve rod. The upper piston valve is disposed within the piston cavity wherein the upper piston valve selectively seals said piston cavity from the combustion chamber. A piston cavity port is disposed on a bottom portion of the piston cavity and is selectively opened and closed with a lower piston valve. The lower piston valve seals the piston cavity port from the lower cylinder portion. This way the gases are selectively sealed in the piston cavity under pressure until released in the combustion chamber.