The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 03, 1983
Filed:
Aug. 27, 1980
Robert Bosch GmbH, Stuttgart, DE;
Abstract
A deformable membrane is made by applying, by thick-film technology, a glass-ceramic paste over a vaporizable or burnable filler material, containing primarily carbon black in a binder which, in turn, is located on a substrate, for example of ceramic, glass, enameled metal or the like. The substrate for example is about 1.5 cm square, the membrane glass ceramic being applied as a circular dot of about 0.5 cm diameter. After solidifying the paste forming the membrane in a protective gas atmosphere, for example at about 950.degree. C., the filler is burned out in an oxidizing atmosphere, to escape through pores in the membrane material. By selecting a membrane material which has a lower thermal coefficient of expansion than that of the substrate, after burning, the membrane will assume a convex shape leaving a hollow space (8) beneath it and the substrate. The membrane is pressure-sensitive, for example when a predetermined quantity of a predetermined gas under a predetermined pressure is sealed therein, or if access to the interior of the space is provided through the substrate, for example by a tiny duct which is connected to a flange or stub connection. Electrical output can be obtained by applying either a metallic layer cover the membrane and utilizing the capacity of the metallic layer with respect to a counter electrode, or applying strain-compression sensitive resistors on the membrane. The membrane, after the electrodes or resistors are applied, is coated with a protective glass glaze (6). The pressure transducer is particularly for determining the pressure conditions in the induction pipe of an internal combustion engine.