US 7,921,724 B2 · Apparatus and method for eliminating varying pressure fluctuations in a pressure transducer

Abstract

A single pressure sensing capsule has a reference pressure ported to the rear side of a silicon sensing die. The front side of the silicon sensing die receives a main pressure at another port. The silicon sensing die contains a full Wheatstone bridge on one of the surfaces and within the active area designated as the diaphragm area. Thus, the difference of the main and reference pressure results in the sensor providing an output equivalent to the differential pressure, namely the main pressure minus the reference pressure which is the stress induced in a sensing diaphragm. In any event, the reference pressure or main pressure may be derived from a pump pressure which is being monitored. The pump pressure output is subjected to a pump ripple or a sinusoidally varying pressure. In order to compensate for pump ripple, one employs a coiled tube. The tube length is selected to suppress the pump ripple as applied to the sensor die. In this manner, the pump ripple cannot cause resonance which would result in pressure amplification and which pressure amplification would destroy the sensor.

Claims19

Dependent claims

A differential pressure transducer for providing an output proportional to a difference between a main pressure P1 and a reference pressure P2, the differential pressure transducer comprising:

a semiconductor sensor comprising an active diaphragm area operative to deflect according to an applied pressure, the active diaphragm area comprising piezoresistors located thereon, the piezoresistors providing a resistance variation according to the applied pressure on the active diaphragm area;
a first port communicating with one surface of the diaphragm via a first channel to provide a first pressure thereto;
a second port communicating with another surface of the diaphragm to provide a second pressure thereto;
and
a coiled tube in series with the second port and dimensioned to suppress a varying pressure fluctuation prior to the application of said second pressure to the diaphragm.

2 more elements

A differential pressure transducer for providing an output proportional to a difference between a main pressure P1 and a reference pressure P2, the differential pressure transducer comprising:

a housing comprising an internal hollow;
a pressure sensor positioned in the housing, the pressure sensor comprising a deflectable diaphragm, wherein the deflectable diaphragm comprises a top surface and a bottom surface, wherein a pressure sensitive element is positioned on the deflectable diaphragm, wherein the pressure sensor provides an output according to a magnitude of deflection of the deflectable diaphragm;
a first port in a surface of the housing for receiving the main pressure P1;
a first channel directed from the first port to communicate with the top surface of the deflectable diaphragm;
a second port in the surface of the housing for receiving the reference pressure P2;
a second channel directed from the second port into the internal hollow;
a tube coupled to the second channel and having a coiled tubular section dimensioned to suppress a ripple caused by operation of a pump, the tube comprising an end communicating with the bottom surface of the deflectable diaphragm to cause the pressure sensor to produce an output proportional to P1−P2.

4 more elements

Dependencies are inferred from the claim text.

Apparatus and method for eliminating varying pressure fluctuations in a pressure transducer

Life of this patent

Apparatus and method for eliminating varying pressure fluctuations in a pressure transducer

Life of this patent

Abstract

Claims19