capacitive differential pressures sensor for ultra-low pressure differences with ueberdrucksicherung a capacitive pressure sensor and method for ueberdrucksicherung.

摘要

A pressure sensor (10) having over-protection for use in environments which subject the sensor to large pressure overloads, such as may occur when such sensor is exposed to jet and automobile engine backfires, explosive gas furnace ignitions and similar high pressure events. Essentially two capacitive sensors are bonded together, diaphragm-to-diaphragm, with the diaphragms (111A/111B) spaced but juxtaposed and forming a closed, reference cavity chamber (114) between them, along with a central, side, wall spacer (116C). The capacitance variation with differential pressure is measured between, the two diaphragms and with reference to their respective bases (112A/112B). Each of the diaphragms preferably is provided with a center bearing or stops (115A/115B) for accepting the load when over-pressured. When in contact at the center, the stiffness of the combined pair of diaphragms is increased several fold over that of a single diaphragm. Furthermore, providing for bottoming stops for the combination on either side of the sensor prevents deflection to the breaking point, because the presence of the opposed bottoming stops stiffens its respective diaphragm.