Two-part piston for an internal combustion engine

• US 7,302,927 B1
• Filed: 06/12/2006
• Issued: 12/04/2007
• Est. Priority Date: 12/17/2005
• Status: Active Grant

• Current Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Scharp, Rainer
• Primary Examiner(s): MCMAHON, MARGUERITE J
• Application Number:
  US11/451,258
• Publication Number:
  US 20070137605A1
• Time in Patent Office: 540 Days
• Field of Search: 922/08, 92215-217, 92219-221, 922/56, 123/193.6
• US Class Current: 123/193.6
• CPC Class Codes: F02F 3/0023 the parts being bolted or screwed together
• CPC Class Codes: F02F 3/22 the fluid being liquid

Abstract

Proposed is a two-part piston 1 for an internal combustion engine, having an upper part 2 that has a pin 31 having an outside thread 32 on the underside of its piston crown 4, and having a lower part 3, which is connected with the upper part 2 by means of a nut 29 screwed onto the pin 31. The lower part 3 has an elastically resilient upper base part 25, onto which an expansion sleeve 26, elastic in the axial direction, is formed, which has an opening 27 having a collar 28, which is directed radially inward, into which the pin 31 is introduced. An elastic compression sleeve 30 is formed onto the nut 29, which sleeve rests against the collar 28. In this connection, the elastic resilience of the base part 25, the expansion sleeve 26, the compression sleeve 30, the pin 31, and the piston crown 4 has the result that the screw connection has a flat characteristic line despite a low compression height of the piston 1, thereby imparting great strength to the screw connection.

Claims

1. Two-part piston (1) for an internal combustion engine,

having an upper part (2) that forms a piston crown (4), and on the underside of which, facing away from the piston crown (4), a cylindrical pin (31) having an outside thread (32), which lies coaxial to the piston axis (12), is disposed,

having a lower part (3), on the underside of which pin bosses (9, 9′

) with pin bores (10, 10′

) and skirt elements (13, 13′

) that connect the pin bosses (9, 9′

) with one another are disposed,

whereby the lower part (3) has an opening (27), on the piston crown side, that lies coaxial to the piston axis (12), in which the pin (31) is guided, and

whereby the upper part (2) and the lower part (3) are connected with one another by means of a nut (29) that is screwed onto the outside thread (32) of the pin (31)

wherein

the lower part (3) has an elastically resilient upper base part (25) that delimits a closed, ring-shaped cooling channel (24) disposed coaxial to the piston axis (12), having oil in-flow and out-flow openings (34, 35), on the skirt side, which channel is delimited by the upper part (2) on the piston crown side,

whereby an expansion sleeve (26) disposed coaxial to the piston axis (12), directed upward, elastic in the axial direction, is formed onto the base part (25), radially on the inside, which forms the radially inner delimitation of the cooling channel (24), and which has the opening (27) on its piston-crown-side end,

whereby the opening (27) is provided with a collar (28), which is directed radially inward,

and that a compression sleeve (30) that lies coaxial to the piston axis (12) and is elastic in the axial direction is formed onto the nut (29), on the piston crown side, which rests against the collar (28) on the piston crown side.

2. Piston according to claim 1, wherein the outside thread (32) is worked into an end region of the mantle surface of the pin (31), facing away from the piston crown, and that the region of the pin (31) between the outside thread (32) and the piston crown (4) has a lesser radial diameter than the outside thread (32).

3. Piston according to claim 1, wherein the nut (29) has at least two bores 39, 40, 41) on the underside, into which pins disposed on a face of an essentially cylinder-shaped wrench fit.

4. Piston according to claim 1, wherein at least one run-off channel (37, 37′

, 37″

) for guiding out the oil situated in a cooling chamber (33) between the pin (31) and the compression sleeve (30) is formed into the outside thread (32) of the pin (31).

5. Piston according to claim 1, wherein a washer (44) is disposed between the compression sleeve (30) and the collar (28).

6. Piston according to claim 1, wherein the surface (45) of the collar (28′

) that stands in contact with the compression sleeve (30′

) and the surface (46) of the compression sleeve (30′

) that stands in contact with the collar (28′

) are configured to narrow toward the piston axis (12), in the direction of the piston crown (4).

7. Piston according to claim 1, wherein the surface (45) of the collar (28′

) that stands in contact with the compression sleeve (30′

) and the surface (46) of the compression sleeve (30′

) that stands in contact with the collar (28′

) are configured to narrow conically towards the piston axis (12), in the direction of the piston crown (4).

8. Piston according to claim 1, wherein the surface (45) of the collar (28′

) that stands in contact with the compression sleeve (30′

) and the surface (46) of the compression sleeve (30′

) that stands in contact with the collar (28′

) have a ball-shaped shape and are configured to narrow towards the piston axis (12), in the direction of the piston crown (4).

9. Piston according to claim 1, wherein a washer (44) is disposed between the surface (45) of the collar (28′

) and the surface (46) of the compression sleeve (30′

).