DK146425B - SEAL FOR A CYLINDER PIECE IN COMBUSTION ENGINES - Google Patents

Description

The invention relates to a seal for a cylinder head in internal combustion engines and of the kind specified in the preamble of the patent claim.

Cylinder tops for self-igniting engines are provided at their bottom with an abutment which serves to seal the combustion chamber relative to the cylinder bush.

For engines with a high degree of overcharging, 10 due to a deformation of the bottom of the cylinder head, the heat expansion of the sleeve and the high combustion pressures often result in a cracking in the foot of the impactor, many times also to a tearing of the foot on part of the circumference. For this reason, cylinder head pieces 15 are used in such engines without abutments to replace sealing rings of different profiles.

Such sealing rings are known of an elastic material whose cross profile has a shape like a lateral letter U, the two arms of this profile forming the upper and lower walls of the ring, and the radial section being on the outside of the ring. The upper wall of the ring is slightly inclined towards the center of the ring. The ring is housed in a recess formed at the circumference of the cylinder sleeve. For the sealing ring, a flat seal is supported on the outside between the motor housing and the cylinder head. A disadvantage of this ring is a relatively complicated shape, to which are added great demands on the material, which must have a sufficiently elastic design even with considerable heat load.

In addition, sealing rings are known of a plastic material and also with a cross profile which is essentially identical to the profile of the sealing rings described above. To obtain a high elasticity, the ring at the inner diameter is provided with a recess. The ring is housed in a circular groove formed partly in the cylinder bush and partly at the bottom of the cylinder head, in which parts the ring is inserted with a bias of the ends of its arms. A disadvantage of this known ring is an intricate shape and a small resistance to high temperatures, so that the cylinder head piece must abut the upper end surface of the cylinder sleeve.

Also known are multi-part sealing rings which are mounted in a circular groove formed at the bottom of the cylinder head. Such a sealing ring consists of a metal ring resting on an upper end surface of the sleeve of the cylinder, with the cylinder having clearance to engage the groove in the cylinder head. On the upper surface lies an intermediate ring with a cross profile in the form of a letter U in which a sealing groove of a plastic material is pressed. Also, with this ring, it is a disadvantage that the ring is considerably complicated.

The present invention aims to provide a seal of the kind in which the above-mentioned drawbacks are avoided, and this is achieved according to the invention in that the sealing ring is formed as indicated in the characterizing part of the claim.

In this configuration with a convex rounding of the upper and lower end surfaces of a steel sealing ring, a certain oscillatory movement of the cylinder head is possible by bending the bottom of this cylinder without causing any disturbance.

The invention is explained in more detail with reference to the drawing, which schematically shows an embodiment. for the seal of the invention.

In a sleeve on a cylinder 1, a circular groove 2 is formed, on the bottom of which is a modified sealing ring 3 of height v with a radial clearance. An upper end face 4 and a lower end face 5 of the sealing ring 3 are convexly rounded with a radius of the rounding, which lies in an area from the six to 10 double to threefold times a width sv of the ring 3- At the bottom of the cylinder head 7 is also formed a circular groove 8 which corresponds to the circular groove 2 in the cylinder bush 1. The cylinder head piece 7 lies with a bottom in a circular groove 8 against the sealing ring 15.

The seal of the cylinder head according to the invention is suitable for internal combustion engines, especially for self-igniting engines with a high degree of overcharging.