CASING COVER IN A JET ENGINE

Abstract

Casing cover (10) in a jet engine, comprising two coaxial shells (36, 38) arranged one inside the other and joined fixedly by radial envelopes (40) inside which extend radial arms (26) of the casing, the cover being fastened at its downstream end to an element of the casing and bearing axially at its upstream end on another element of the casing, and the cover having, in the free state, an axial dimension (D) of less than the axial distance (L) between the points where its downstream end is fastened to the casing and the points where its upstream end bears axially on the casing, and being tensioned axially when it is mounted on and fastened to the casing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and other details, features and advantages of the present invention will become apparent on reading the description given below by way of nonlimiting example and with reference to the appended drawings, in which:

FIG. 1 is a schematic half-view in axial section of an exhaust casing cover according to the invention;

FIG. 2 is a view on an enlarged scale of the means for fastening the cover shown in FIG. 1;

FIG. 3 is a view on an enlarged scale of the means for the axial bearing of the cover shown in FIG. 1.

Claims

1. A casing cover in a jet engine, comprising two coaxial shells arranged one inside the other and joined fixedly by radial envelopes inside which extend radial arms of the casing, the cover being fastened at its downstream end to an element of the casing and bearing axially at its upstream end on another element of the casing, wherein the cover has, in the free state, an axial dimension of less than the axial distance between the points where its downstream end is fastened to the casing and the points where its upstream end bears axially on the casing, and is tensioned axially when it is mounted on and fastened to the casing.

2. The casing cover as claimed in claim 1, wherein the difference between the axial dimension of the cover, in the free state, and the axial distance between the points where its downstream end is fastened and the points where its upstream end bears axially is substantially equal to the maximum deviation between the axial thermal expansion of the cover and the axial thermal expansion of the casing during the operation of the jet engine.

3. The casing cover as claimed in claim 2, wherein the difference is approximately 1 to 1.2 millimeters.

4. The casing cover as claimed in one of the preceding claims, wherein the cover is fastened at its downstream end to a flange of a bearing support by means of bolts and comprises, at its upstream end, an outwardly oriented radial lip, this radial lip being situated to the inside and upstream of a radial lip formed at the upstream end of an element of the casing, the radial lip of the upstream end of the cover bearing axially on the radial lip of the casing shell when the cover is mounted on the casing.

5. The casing cover as claimed in claim 4, wherein the radial lip of the upstream end of the cover is formed on an outer shell of the cover which, as a result of thermal expansion, can bear radially on the casing element during the operation of the jet engine.

6. A jet engine which comprises at least one casing cover, in particular an exhaust casing cover, as claimed in one of the preceding claims.