Differential fluid pressure measurement apparatus

Abstract

A differential liquid pressure sensor (10) has an upper housing (12) that mounts a connector portion (12a) and receives in a recess a sense element module (14). The sense element module is a body in which a generally U-shaped oil filled passageway (14h) is formed with openings at opposite ends provided on respective first and second diaphragm mounting surfaces. A fluid pressure sense element, such as a piezoresistive sense element (15) is disposed in one of the passageway openings and flexible metal diaphragms (14a, 14b) are mounted on the respective diaphragm mounting surfaces of the module facing a common direction. A lower housing (18) having first and second port connections for the respective diaphragms is disposed on the lower surface of the module.

Description

FIELD OF THE INVENTION [0001]This invention relates generally to apparatus for measuring fluid pressure and more particularly to such apparatus providing a media isolated differential pressure sensor using two diaphragms for placement in fluid communication with respective high and low pressure sources.BACKGROUND OF THE INVENTION [0002]Solid state pressure sense elements, such as piezoresistive pressure sense elements, are often isolated from the sensed media by a flexible metal diaphragm robust to the media to protect such sense elements. An incompressible fluid, typically silicone oil, is used to transfer pressure from the diaphragm to the sense element. It is conventional to provide first and second diaphragms facing opposite directions with the sense element disposed therebetween. To reduce the accumulation of substances, such as soot, water, condensate from the media on the diaphragm that could damage the sensor, it is often required to place the diaphragms in a drainable orien...

AI Technical Summary

Benefits of technology

The present invention provides a differential fluid pressure sensor that can be easily oriented, is compact and can be made of less expensive materials than typically required. The sensor's structure allows for time-saving assembly operations. The sensor has a base with a passageway between openings at two diaphragm mounting surfaces that face a common direction. The diaphragms and the passageway form two chambers that are filled with incompressible oil to transmit pressure to the sensor. The sensor is connected with wire bonds to one end of terminal pins with the other end of the pins bonded to a printed circuit board having conditioning circuits and this in turn is connected to connector terminals by means of metal springs. A sealant is placed around the pins to prevent oil leaks through the pin / base interface.

Problems solved by technology

Further, mounting of the diaphragms so that they face in opposite directions can result in having to use separate housing members that each needs to be robust with the sensed media.

Images