Liquid-Cooled Composite Piston

• US 20090139481A1
• Filed: 09/02/2006
• Published: 06/04/2009
• Est. Priority Date: 09/05/2005
• Status: Active Grant

• Current Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Messmer, Dieter
• Granted Patent: US 7,934,482 B2
• Time in Patent Office: Days
• US Class Current: 123/193.600
• 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 proposes a liquid-cooled assembled piston (1) having an upper part (2) and a lower part (3), wherein the upper part (2) and the lower part (3) are connected to one another by means of a radially outer annular support (12) and by means of a radially inner annular support (11). An outer cooling duct (13) is arranged between the outer support (12) and the inner support (11), and an inner cooling duct (18) is arranged radially within the inner support (11). Here, the outer cooling duct (13) is connected to the inner cooling duct (18) by means of at least one overflow duct (22, 22′). According to the invention, in order to reduce the compression height and therefore the axial dimensions of the piston, and in order to ensure an unimpeded discharge of cooling oil situated in the inner cooling duct (18) with little design expenditure, a bolt (20) with an outer thread (23) is arranged coaxially with respect to the piston axis (17) on the underside, which faces away from the piston head, of the piston head (4); the upper part (2) and the lower part (3) of the piston (1) are screwed to one another by means of a hexagonal nut (19) which can be screwed onto the outer thread (23) of the bolt (20); and the hexagonal nut (19) has, at the piston head side, a collar (25) with at least one radially arranged bore or milled portion (26, 27) which connects the inner cooling duct (18) to the piston interior space (28).

Claims

1. Liquid-cooled composite piston (1)

having an upper part (2) that has a piston crown (4) and a ring wall (5) having a top land (6) and having a ring belt (7), and

having a lower part (3) that has pin bosses (8, 8′

) having pin bores (9, 9′

) and skirt elements (10, 10′

),

whereby the upper part (2) and the lower part (3) stand in connection with one another by way of a radially outer ring-shaped contact surface (12) and by way of a radially inner ring-shaped contact surface (11),

whereby an outer cooling channel (13) is disposed between the outer contact surface (12) and the inner contact surface (11), and an inner cooling channel (18) is disposed radially within the inner contact surface (11),

whereby the piston interior (28) is connected with the outer cooling channel (13) by way of at least one oil feed channel (16), and the outer cooling channel (13) is connected with the inner cooling channel (18) by way of at least one overflow channel (22, 22′

),

wherein

a pin (20) having an outside thread (23) is disposed on the underside of the piston crown (4), facing away from the piston crown, coaxial to the piston axis (17),

the upper part (2) and the lower part (3) of the piston (1) are screwed together by means of a hexagonal nut (19) that can be screwed onto the outside thread (23) of the pin (20), and

the hexagonal nut (19) has a collar (25) on the piston crown side, having at least one radially disposed bore or milling (26, 27), which connects the inner cooling channel (18) with the piston interior (28).