Applicant claims priority under 35 U.S.C. §119 of German Application No. 10 2004 019 011.9 filed Apr. 20, 2004. Applicant also claims priority under 35 U.S.C. §365 of PCT/DE2005/000717 filed Apr. 19, 2005. The international application under PCT article 21(2) was not published in English.
The invention relates to a cooling channel cover for a piston of an internal combustion engine, in accordance with the preamble of claim 1.
It is known from the patent document DE 42 08 037 to provide a piston for an internal combustion engine with a cooling channel that lies radially on the outside and is open towards the piston skirt, in the region of the piston crown. To improve the cooling effect of the cooling oil that is introduced into the cooling channel, the cooling channel is closed off by means of a cooling channel cover, in which there are openings for conducting the cooling oil in and out. It is also known to give the cooling channel cover the shape of a two-part plate spring, which (see
In this connection, however, relative movements of the ring wall 24 relative to the piston base body 28 occur, as indicated by the arrow 27, during engine operation, because of the pressure of the combustion gases on the piston, but also because of the mass forces that act on the ring wall 24 due to the back and forth movements of the piston. This also results in relative movements of the plate spring, particularly relative to the ring wall 24, in the region of the contact points 31 and 32, and this leads to damage both of the plate spring 30 and of the recess 22 in this region.
Another disadvantage of the cooling cover known from the state of the art, consisting of two plate spring halves in semi-circular shape, consists in the fact that forces that are directed both axially and radially are exerted on the ring wall 24 by this. These forces are maximal at the abutting ends of the plate spring halves, so that the axial forces in this region lead to a non-sine-shaped deformation of the piston ring grooves in this region, which the piston rings accommodated in them cannot follow, thereby increasing the oil consumption of an internal combustion engine equipped with the piston in question, in particular. The radially directed forces, which are maximal at the abutting ends of the plate spring halves, result in an oval deformation, in cross-section, of the ring wall 24 here, bringing with it the risk of piston scoring.
Proceeding from this, the invention is based on the problem of avoiding the aforementioned disadvantages of the state of the art.
The problem is solved with the characteristics indicated in the characterizing part of the main claim. A practical embodiment of the invention is the subject of the dependent claim.
The invention will be described below, using the drawings. These show:
In
The spring metal sheet 1 has an outside radius 11 (
Furthermore, the surfaces of the supports 9 and 10 are so great that minimal wear occurs here in the case of relative movements between piston 8 and spring metal sheet 1.
These relative movements are the result both of the combustion pressure acting on the piston 8 and of the mass forces that act on the ring belt 13 in the case of higher speeds of rotation, thereby bringing about the result that the ring belt 13 moves relative to the piston base body 14, leading to relative movements of the spring metal sheet 1 both relative to the ring belt 13 and relative to the piston base body 14.
During assembly, the two spring metal sheet halves 2 and 3 are laid against the underside 15 of the ring belt 13, facing away from the piston crown, exposed to an axial force that acts in the direction of the piston crown 21 on their radial inside, and thereby put into torsion to such an extent that the radially inner edge region 16 of the spring metal sheet halves 2, 3 comes to lie above the first support 10. Afterwards, the spring metal sheet halves 2, 3 are pushed into their position as shown in
Number | Date | Country | Kind |
---|---|---|---|
10 2004 019 011 | Apr 2004 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE2005/000717 | 4/19/2005 | WO | 00 | 11/13/2006 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2005/103473 | 11/3/2005 | WO | A |
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Number | Date | Country | |
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20070209614 A1 | Sep 2007 | US |