Patent attributes
A housing with a first main wall and a second main wall which each extend perpendicularly of a temperature gradient, and auxiliary walls connecting both main walls and extending parallel to the temperature gradient, wherein the auxiliary walls connect with ribs to the main walls, and a filling placed in the housing and able to withstand pressure forces, wherein the pressure within the housing is reduced to a value at which no heat transfer of any significance takes place, and wherein the housing is manufactured from metal, wherein a strip of the auxiliary wall contacting a rib is welded to the main wall, and that a welding strip is welded onto the weld. With mere welding of a sufficiently thin metal foil it is practically impossible to obtain a weld of sufficient quality. With a sandwich weld it is possible to obtain a sufficiently strong and reliable welded connection, even when a very thin metal foil is used as auxiliary wall.
