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:
Jun. 06, 1995
Filed:
Jun. 04, 1993
Asea Brown Boveri Ltd., Baden, CH;
Abstract
The device serves to measure the density of a gas, in particular of the insulating gas of a gas-insulated electrical installation. It contains two resonators (11, 12) each comprising a piezoelectric crystal (14, 15) and each comprising two electrodes applied to the crystal. A first (11) of the two resonators (11, 12) is mounted in a first chamber (5) containing the gas to be measured, whereas a second (12) is mounted in a second chamber (6) sealed with respect to the gas. Despite small dimensions and despite simple and robust construction, this device is intended to have a high measurement precision over a long period of time. This is achieved by drawing the two resonators (11, 12) from a multiplicity of similar resonators manufactured by mass production and not subjected to a frequency alignment. The first resonator (11) is unaltered with respect to the manufacture in mass production. The second resonator (12) is likewise unaltered with respect to the manufacture in mass production and, under vacuum and with equality of temperature, it has the same resonance frequency as the first resonator (11) within a specified frequency tolerance. The second resonator (12) may, however, also be modified, by altering its electrodes (18, 19), in such a way that, under vacuum and with equality of temperature, it has the same resonance frequency as the first resonator (11) within the specified frequency tolerance.