Electric motor housing with end cap

DETAILED DESCRIPTION In FIG.
1 a cylindric housing is shown comprising a shell 10 and an end cap 11.
The end cap 11 is in known manner punched out from a planar blank and embossed in a shape as is known from wiper motors.
End cap 11 has a supporting rim 12 which, in the relaxed position, lies in a plane.
The contour of this supporting rim is adapted to the inner wall of the shell 10 and thus in the present case is circular.
Several supporting elements 13 are embossed or cut out of this shell towards the interior.
These supporting elements 13 have supporting surfaces 14 which lie in a plane and upon which rests one side of the supporting rim 12.
In the circumferential direction and offset to supporting elements 13, holding elements 15 are cut out of the shell.
The holding elements have supporting surfaces 16 to which the other side of the supporting rim 12 is adjacent.
In the present invention, the axial arrangement of the supporting elements 13 and of the holding elements 15 relative to a plane of reference is significant.
In this embodiment, the plane E defines the front side of the shell 10.
The spacing of the supporting surface 14 of the supporting element 13 from this plane of reference E is designated A1 in FIG.
1.
The spacing of the supporting surface 16 of the holding element 15 from this plane E is designated A2.
In the motor housing according to the aforementioned British patent the spacing A2 is exactly as large as the spacing A1 minus the sheet metal thickness D of the end cap 11.
This means that in this known embodiment the supporting rim 12 lies in a plane even after the end cap 11 has been fastened on the shell 10.
In contrast thereto, the spacing A2 of the present invention shall be greater than the spacing A1 minus the thickness D.
This means that the supporting rim 12 can no longer lie in a plane and, seen in the circumferential direction, gets a corrugated contour.
Thus the supporting rim 12 is prestressed from its original shape.
Due to the elasticity of the material, the supporting rim 12 has the tendency to occupy its relaxed condition, so that forces act upon the holding elements and upon the supporting elements which provide a solid connection free from play between the shell 10 and the end cap 11