Cooled multi-component piston for internal combustion engines

Details Cooled multi-component piston for internal combustion engines Cooled multi-component piston for internal combustion engines

1993-06-10

1994-10-25

Kamen, Noah P.

Internal-combustion engines

Particular piston and enclosing cylinder construction

Piston

92186, F02F 300

Patent

active

053579208

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a cooled multi-component piston for internal combustion engines.
2. The Prior Art
This type of piston is known, for example, from DD 2 638 A. In this known piston, the annular wall parts for covering an annular cooling duct are slotted rings which are installed under stress on the inside or outside thereof. An axial stressing of the ring is present to some extent as well. To the extent to which the rings are axially stressed either on the inside or outside, the edge of the ring that is in each case radially removed from the clamping point is axially unsupported.


SUMMARY OF THE INVENTION

It is an object of the present invention to create an annular cover wall which, at the same time, is radially safely locked on the inside and outside against axial displacement. Furthermore, the cover wall is secured in a simple, destruction-free and operationally safe manner.
The above object is achieved according to the present invention by providing that the annular wall part, which is divided on its circumference into at least two separated annular segments, has radially both on the inside and outside a collet extending all around. With this collet, it engages radially on the inside and outside with radial clamping, in mating, form-locking recesses on the inner circumference on the outer annular rib of the piston and in the boss support disposed within the piston, respectively. In this regard, radial clamping is achieved through an elastic deformation of the collets in the direction perpendicular to the longitudinal axis of the piston.
According to the solution of the prior art problem by the piston of the invention, such elastic deformation of the collets in the installed condition constitutes a very important feature. Due to its accommodation on the inside and outside, the wall part can be safely secured in a simple way in an elastic snap lock on the head part of the piston. Furthermore, the double clamping permits thin wall thicknesses for the wall part, because the latter has no freely swinging zones, as is the case with the annular connection part according to the above-mentioned prior art document.
For accomplishing the radial clamping, it is important that provision is made on the collet for radial slots radially on the inside and outside, so that radially elastic lashings are obtained distributed across the circumference of the annular wall part. The required elastic clamping of the wall part would not be possible with unslotted, through-extending collets. This constitutes another difference vis-a-vis the design of an annular cooling duct cover known from the above-mentioned prior art reference.
Furthermore, special importance has to be attributed to the feature that the annular wall part is divided on its circumference at least once, i.e., that at least two annular segments are present. Only such division permits using the annular wall part with piston head parts having bosses whose outside diameters project significantly beyond the inside diameter of the radial inner sealing of the cooling duct, because in such cases, annular covers of the type according to DD 252 638 A cannot be installed. Such known annular sealings are radially slotted only once, so that a ring is obtained that is spread open. Such a ring, however, is radially expandable only to a minor extent if it is to retain its clamping effect and if its material is not to be damaged during spreading. Such minor measure does in many cases not suffice to assist in mounting such a ring. With the design according to the aforementioned prior art reference, this constitutes a very decisive difference. This difference is serious particularly because a cover ring according to the prior art reference which, for example, is divided into two separate halves, could not be secured at all in any functionally safe manner according to the disclosure of said reference.
The differences and advantages specified above vis-a-vis DD 252 638 A are valid vis-a-vis U.S. Pat. No. 4,377,9

REFERENCES:
patent: 1900521 (1933-03-01), Price
patent: 4377967 (1983-03-01), Pelizzoni
patent: 4986167 (1991-01-01), Stratton et al.
patent: 5052280 (1991-10-01), Kopf et al.
patent: 5144923 (1992-09-01), Leites et al.

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