Coolable trunk piston for internal combustion engines

Details Coolable trunk piston for internal combustion engines Coolable trunk piston for internal combustion engines

1990-11-05

1991-10-01

Look, Edward K.

Expansible chamber devices

Piston

With ported chamber in piston part for circulating heat...

92159, 92190, 123 4135, F02F 322, F02F 300

Patent

active

050522809

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a coolable trunk piston for internal combustion engines.
Such pistons are known from U.S. Pat. No. 4,377,967. The wall part (shaped sheet metal) which is used in those pistons to cover the cavity which forms the cooling oil space is flanged onto the outer periphery of the annular wall which carries the piston rings. This type of fixing is not secure, because flanging of the relatively thin-gauge wall part can become detached in the long term under the conditions in which engines operate.
The use of a one-piece thick gauge and thus, by reason of its greater rigidity, a wall part which guarantees a more reliable attachment is in turn undesirable for different reasons. The outer annular part of the piston head which accommodates the piston rings ought during operation of the engine to be able to change its shape at its bottom end without being hindered by the incorporated wall part. Such deformations take place due to the combustion processes which take place in the manner of explosions and, if they are inhibited, they can cause cracks in the piston head material. In this respect, one-piece sheet metal covering such as are known from FR-A 23 23 022 or coverings which consist of individual parts rigidly connected to each other, such as are described in the case of pistons in U.S. Pat. No. 2,698,210 are equally unsuitable for the necessary covering of the annular cooling oil cavity.
It is on this premise that the invention is based on the problem in the case of the piston known from U.S. Pat. No. 4,377,967, of providing a covering which ensures on the one hand movements of the bottom end of the outer annular wall of the piston head while on the other is sufficiently securely attached to the piston head.


SUMMARY OF THE INVENTION

This problem is resolved by an embodiment of construction and attachment of the wall part which covers the cooling oil cavity.
The collar projecting from the annular wall and which is flanged over the wall part can be made substantially thicker than the wall part itself and it can therefore provide a more rugged flanged connection. The existence of joints between the multi-part covering wall guarantees the necessary freedom of movement of the outer annular wall of the piston head. In addition, the fact that the wall part is in more than one part makes it possible completely to cover the entire open surface of the annular cooling oil space. If the wall part were made in one piece, on the other hand, this would not be possible because the cross-sections of the gudgeon pin bosses of the piston head taper from the free end of their respective bosses towards the crown of the piston head, so that a one-piece wall part which completely covers the annular cooling oil space could not be pushed over the bosses.
Alternative solutions to the problem are the objects of the present invention.
Expedient further developments of the solutions according to the invention are contained in the sub-claims.
Other advantages and features of the invention will be apparent from the disclosure, which includes the above and ongoing specification with the claims and the drawings.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section through a piston,
FIG. 2 shows a section taken through the piston as indicated by the arrows II--II,
FIG. 3 is a detail from a longitudinal section through a piston having a welded-on covering wall and
FIG. 4 is a detail from a longitudinal section through a piston having a screwed-on covering wall.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Altogether, the piston consists of a head part 1 on the boss 2 of which a piston skirt 3 is articulated via a gudgeon pin, not shown.
From the crown of the head part 1, extends an annular wall 4 containing the grooves for the piston rings. Spaced apart radially within the annular wall 4, an annular rib 5 connects the bosses 2 to the piston crown. Between the annular rib 5 and the annular wall 4 there is an annular cavity 6 which is covered by a sheet metal part 7 shaped

REFERENCES:
patent: 1825163 (1931-09-01), Schweter
patent: 2698210 (1954-12-01), Baller
patent: 3336844 (1967-08-01), Cornet
patent: 3805677 (1974-04-01), Clary et al.
patent: 4377967 (1983-03-01), Pelizzoni
patent: 4505233 (1985-03-01), Kanda et al.
patent: 4506632 (1985-03-01), Kanda et al.

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