Composite Piston for an Internal Combustion Engine

• US 20080060514A1
• Filed: 06/20/2005
• Published: 03/13/2008
• Est. Priority Date: 06/22/2004
• Status: Active Grant

• Current Assignee: Mahle GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Scharp, Rainer
• Granted Patent: US 7,584,694 B2
• Time in Patent Office: Days
• US Class Current: 92/221
• CPC Class Codes: F02F 3/0023 the parts being bolted or screwed together
• CPC Class Codes: F02F 3/22 the fluid being liquid

Abstract

The invention relates to an assembled piston (1) for an internal combustion engine, said piston consisting of an upper part (4) provided with a combustion cavity (8), and a lower part (5) that is screwed to the upper part (4) by means of a screw (6) which is arranged coaxially to the piston axis (31). Said screw (6) is embodied as a set screw comprising a hexagon socket (6′) on the inner side of the piston and a head (6″) on the bottom side of the piston, the head (6″) forming part of the bottom of the combustion cavity (8) and being flush therewith (8) in the screwed state.

Claims

1. Composite piston (1) for an internal combustion engine

consisting of an upper part (4) that forms the piston crown (7), having a combustion bowl (8),

having a recess (20) disposed on the underside facing away from the piston crown, and circumferential with rotation symmetry relative to the longitudinal piston axis (31),

consisting furthermore of a lower part (5) that is screwed together with the upper part (4) using a screw (6) disposed coaxial to the piston axis (31),

having two pin bosses (27, 27′

) disposed on the underside at a distance from one another, each having a pin bore (3, 3′

),

having skirt elements (32, 32′

) that connect the pin bosses (27, 27′

) with one another,

having a recess (21) disposed on the top and circumferential with rotation symmetry relative to the longitudinal piston axis (31), which recess forms an inner cooling channel (22) together with

wherein the recess (20) of the upper part (4),

a continuous circumferential bore (34) having a recess (35) on the piston crown side is worked into the upper part (4), coaxial to the piston axis (31), which recess has a greater radial diameter as compared with the bore (34),

a passage bore (36) with inside thread (37) is worked into the lower part (5), coaxial to the piston axis (31), the radial diameter of which bore is slightly less than the diameter of the continuous bore (34), and

the screw is configured as a threaded pin (6) having an outside thread (38) identical to the inside thread (37), having a hexagonal socket (6′

) on the piston inside, and having a head (6″

) having a shape that is complementary to the recess (35), on the piston crown side, in such a manner that the head (6″

) forms part of the bottom of the combustion bowl (8) and ends flush with the bottom of the combustion bowl (8) in the screwed-together state.

2. Composite piston according to claim 1, wherein the recess (21) is worked into the lower piston part (5) so far that a thin-walled region (33) is formed between piston interior (24) and recess (21), which region can be deformed in the manner of a disk spring, and has the passage bore (36) with the inside thread (37).