Piston with a central cooling chamber

Details Piston with a central cooling chamber Piston with a central cooling chamber

2000-04-21

2001-03-20

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Particular piston and enclosing cylinder construction

Piston

Reexamination Certificate

active

06202619

ABSTRACT:

The invention relates to a piston for an internal combustion engine, with a piston head and a central cooling chamber located beneath the piston head. Such a piston is known from JP patent 60-125338. The lower wall of the cooling chamber is formed by a sheet metal plate, which is secured on the piston under initial spring tension. In the upper zone of the inner bosses, the sheet metal plate is supported by means of molded-on tabs.
One drawback of said construction is that the sheet metal plate has a complicated shape. Another drawback of the known construction is that it is not possible for strength reasons to provide all pistons with a support surface on the inner bosses for a sheet metal plate that has to be supported.
Another possibility for providing a central cooling space is shown by WO 88/04725, where a sheet metal plate is screwed to the piston in the zone located between the boss supports of an articulated piston. However, substantial expenditure is required in particular for cutting the thread and for safely securing the screws.
Therefore, the invention is dealing with the problem of providing a piston with a central cooling chamber and a sheet metal plate forming the lower wall of the cooling chamber, in connection with which piston the aforementioned drawbacks are not present, and where particularly a simple sheet metal plate suffices to serve as the lower wall of the cooling chamber.
Said problem is solved in connection with pistons of the type specified above by a design with the characterizing features of claim
1
or
5
. Advantageous further developments of the invention are the objects of the dependent claims.
The sheet metal plate, which consists of spring steel, is supported and initially tensioned by the pin located above the boss of the pin, so that its ends abut the bridges with a defined force of contact pressure, said bosses connecting the bosses with one another.
FIG. 3
shows that the pin supporting the sheet metal plate can be manufactured in the form of a hollow body, or said pin may consist of full material. Steel is preferably employed as the pin material.
Also, the bore receiving the pin may be designed in the form of a blind bore on one side.
The surfaces contacted by the sheet metal plate need not to be worked.
The position of the sheet metal plate in relation to the piston can be exactly defined at the same time by a corrugation shaped in the plate via which the plate rests against the pin, as compared to plates whose installed position is defined by the contact with the relatively imprecise inner shape of the piston.
The volume of the central cooling chamber can be changed, if need be, by varying the position of the pin supporting the plate in the direction of the longitudinal axis of the piston, and by adapting of the shape of the plate, with no change of the inner form of the piston.
In the direction of the boss supports, the plate has a defined gap or recesses, which permit controlled drainage of the cooling oil. The position of said drainage openings can be advantageously selected, if need be, in such a way that draining oil lubricates also the bore of the piston pin.
It is known from DE 40 39 754 to support a sheet metal part limiting the outer cooling channel by a clamping pin pressed into the boss support, whereby the plate rests on the pin with one face side or edge, causing substantial pressure to be applied to the edge. However, a pin or clamping pin extending between the two boss supports, against which the plate is supported over its entire width as defined by the invention, cannot be derived from the above known construction.


REFERENCES:
patent: 3221718 (1965-12-01), Isley
patent: 4506632 (1985-03-01), Kanda et al.
patent: 4867119 (1989-09-01), Cooper et al.
patent: 5144923 (1992-09-01), Leites et al.
patent: 5653204 (1997-08-01), Shaffer
patent: 5778533 (1998-07-01), Kemnitz
patent: 5934174 (1999-08-01), Abraham et al.
patent: 6026777 (2000-02-01), Kemnita et al.
patent: 1 301 677 (1969-08-01), None
patent: 37 08 376 (1987-09-01), None
patent: 37 17 767 (1988-12-01), None
patent: 37 35 590 (1989-01-01), None
patent: 40 39 754 (1990-12-01), None
patent: 60-30455 (1985-02-01), None
patent: 60-125338 (1985-08-01), None
patent: WO 88/04725 (1988-06-01), None
patent: WO 92/10659 (1992-06-01), None
patent: WO 99/23380 (1999-05-01), None

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