Piston for an internal combustion engine

Claim 2

A sealing structure for a piston of an internal combustion engine comprising: a piston (12, 50, 80) formed with a plurality of grooves (14 16 18, 52 54 56, 82 84 86, 113, 134) around the periphery thereof, said piston including means for providing a lubricant oil to establish a lubricant oil layer between said piston and a cylinder wall (32, 76) of the engine cylinder, an oil-control ring (26, 64, 102) mounted in the groove (18, 56, 86) in the lowermost position in relation to the other grooves; and a pair of piston rings (20 22, 58 60, 88 90, 110 112, 120 122, 130 132, 140 142) disposed in one of said grooves (14, 52, 82, 113, 134) other than the lowermost one, being spaced from each other and movable with respect one another and with respect to the cylinder wall.

Claim 3

A sealing structure as set forth in claim 1, characterised in that said pair of piston rings are arranged in said groove so that the piston ring which is trailing with respect to the direction of motion of the piston serves to scrape the lubricant oil from the cylinder wall and introduce the scraped lubricant oil into the space defined between said piston rings.

Claim 4

A sealing structure as set forth in claim 1, characterised in that said one of said grooves receiving said pair of piston rings is dimensioned so as to permit free motion of the piston rings in the radial and axial directions therein.

Claim 5

A sealing structure as set forth in claim 3, characterised in that said space between said piston rings is variable according to the relative motion of the two piston rings and is filled with the lubricating oil.

Claim 6

A sealing structure as set forth in any one of claims 1 to 4, characterised in that said structure further comprises a means (70, 96) for sealingly closing the radially inner end of the space defined between said piston rings.

Claim 7

A sealing structure for a piston of an internal combustion engine comprising: a piston (50, 80) disposed within an engine cylinder (76) of the engine for reciprocation therewithin and being formed with first and second circumferentially extending grooves (52 56, 82 86) on the periphery thereof; an oil-control ring (64, 86) mounted in said second groove (56, 86) to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; a pair of piston rings (58 60, 88 90) disposed within said first groove (52, 82) and being spaced from each other and said piston rings having dimensions so as to be freely movable within said first groove in the vertical direction; and means (70, 96) for sealingly closing the radially inner end of the space defined between said piston rings.

Claim 8

A sealing structure for a piston of an internal combustion engine comprising: a piston (50, 80) disposed within an engine cylinder (76) of the engine for reciprocation therewithin and being formed with first and second circumferentially extending grooves (52 56, 82 86) on the periphery thereof; an oil-control ring (64, 86) mounted in said second groove (56, 86) to control the amount of lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; a pair of piston rings (58 60, 88 90) disposed within said first groove (52, 82) and being spaced from each other and said piston rings having dimensions so as to be freely movable within said first groove in the vertical direction; and means (70, 96) for sealingly closing the radially inner end of the space defined between said piston rings.

Claim 9

A sealing structure for a piston of an internal combustion engine comprising: a piston (50, 80) disposed within an engine cylinder (76) of the engine for reciprocation therewithin and being formed with first and second circumferentially extending grooves (52 56, 82 86) on the periphery thereof; an oil-control ring (64, 86) mounted in said second groove (56, 86) to control amount of the lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; a pair of piston rings (58 60, 88 90) disposed within said first groove (52, 82), said piston rings having dimensions suitable for free vertical motion in said first groove and said piston rings defining therebetween a space into which lubricant oil is introduced during the piston stroke, the space between said piston rings being variable according to the relative position of the piston rings; and means (70, 96) for sealingly closing the radially inner end of the space defined between said piston rings.

Claim 10

A sealing structure for a piston of an internal combustion engine comprising: a piston (50, 80) disposed within an engine cylinder (76) of the engine for reciprocation therewithin and being formed with first and second circumferentially extending grooves (52 56, 82 86) on the periphery thereof; an oil-control ring (64, 86) mounted in said second groove (56, 86) to control amount of the lubricant oil to be supplied between the piston and the cylinder wall of the engine cylinder; a pair of piston rings (58 60, 88 90) disposed within said first groove (52, 82), said piston rings having dimensions suitable for free vertical motion in said first groove and said piston rings defining therebetween a space into which lubricant oil is introduced during the piston stroke, the space between said piston rings being variable according to the relative position of the piston rings; and means (70, 96) for sealingly closing the radially inner end of the space defined between said piston rings.

Claim 11

A sealing structure as set forth in any one of claims 1 to 4, characterised in that said closing means is a sealing ring 96 disposed within said one groove (82) in a position sealingly contacting the radially inner surfaces of said piston rings.

Claim 12

A sealing structure as set forth in claim 5, 6, or 7 characterised in that said closing means is a resilient member (70) disposed within said one groove (66) to urge one of said piston rings (58) toward the other piston ring (60) to resilient contact the radially inner end of said other piston ring.

Claim 13

A sealing structure as set forth in claim 8, characterised in that said piston rings have different tension.

Claim 14

A sealing structure as set forth in claim 8, characterised in that said piston rings (130 132, 144 46) have different configurations with respect to each other.