JPS5522125A - Pressure sensor - Google Patents

Abstract

PURPOSE: To detect at least two absolute pressure levels with the use of one sensor by bringing the gas introducing side and vacuum space side of a pellet into contact with cover members having substantially the same thermal expansion coefficient as that of the pellet.

CONSTITUTION: An absolute pressure sensor is composed a refractory glass plate 1, a pellet 2 made of a single crystal of semiconductor, a refractory glass pipe 3 and the like, which pipe 3 is fixedly connected to a pipe 5 made of metal or the like. A pressure-sensitive diaphragm chamber 19_a is vented to the atmosphere through a hole, which is formed in the form of a groove in parallel with the upper side of the pipe 3, and through a hole 21 which is formed in the side wall of the pipe 5. Likewise, a chamber 19_b introduces the pressure in the manifold of an engine through a through hole 22 extending at a right angle with respect to the hole 21 and through a hole 23 in the pipe 5. Strain gauges 25_a and 25_b, which are diffused in the pressure- sensitive diaphragms 9_a and 9_b of the pellet 2 have their resistances varied in accordance with the pressure to be introduced into the chambers 19_a and 19_b so that the bottomed hole 10 in the glass plate 1 can be held under vacuum. As a result, the atmospheric pressure and the absolute pressure in the manifold can be simultaneously detected by the variation in the resistance.

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