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US 5,844,141 AGranted
Pressure sensor having stress sensitive member
AssigneeSolartron Group Limited
InventorJames Wolryche Stansfeld
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AssigneeSolartron Group Limited
InventorJames Wolryche Stansfeld
Estimating the term…
A pressure sensor device 10 comprises three layers 11a, 12 and 11b of silicon, fusion-bonded together. The outer layers 11a and 11b form a sealed housing around the central layer 12 to which they are bonded, and in use a cavity 13 between the housing 11a, 11b and central layer 12 is evacuated. The sensor device 10 is normally placed inside a component for containment of a pressurised fluid (not shown). Due to the cross-sectional shape of the device 10, pressure exerted by the fluid causes the layers 11a and 11b to flex inwardly in the region of minimum cross-sectional dimension and thereby outwardly in the region of maximum cross-sectional dimension, thereby is placing under tension a balanced twin beam vibratable element 16 on the central layer 12. The tension across the vibratable element affects its resonant frequency of vibration. Accordingly by accurately measuring the resonant frequency of vibration of the element, and by comparing this to previous calibration data, the magnitude of the pressure exerted on the layers 11a and 11b may be determined. The device may be made in other materials such as quartz and/or include temperature compensation facilities.
A pressure sensor device for sensing fluid pressure, the device comprising a pressure-sensitive housing and a bridge member located within and attached to the housing and extending across a cavity therein, to form a stress-sensitive member arranged to be placed in stress by the housing in response to pressure exerted on the housing, characterized in that the sensor device comprises first, second and third substantially rectangular layers, the first and second layers substantially forming the housing and the third layer forming the bridge member, the third layer being located between the first and second layers and defining an aperture, wherein the stress-sensitive member extends across the aperture between edge regions of the third layer in a direction transverse to the longer dimension of the substantially rectangular third layer.
A method of fabricating a pressure sensitive device, for sensing fluid pressure, characterized in that, the method comprises forming a pressure-sensitive housing of the device from substantially rectangular first and second layers of material, forming a bridge member from a substantially rectangular third layer of said material, forming an aperture on a portion of the bridge member, forming a stress-sensitive element across the aperture between edge regions of the third layer, so that the stress-sensitive element extends in a direction transverse to the longer dimension of the substantially rectangular third layer, and bonding the layers together, wherein the third layer is located between the first and second layers, such that the stress-sensitive element is arranged in use to be placed under stress by the housing in response to pressure exerted on the housing.
Dependencies are inferred from the claim text.