Microflow based differential pressure sensor
First Claim
1. A differential pressure sensor comprising:
- a fluid channeling device having a fluid channel defined therethrough and a fluid flow detector located in said fluid channel;
a circuit coupled to said fluid flow detector for detecting a change in fluid flow through said fluid channel; and
memory having stored therein a characteristic of said fluid channeling device.
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Abstract
A differential pressure sensor based on pressure induced micro-flow that includes two connecting hoses that are considered when the pressure sensor is calibrated. The inventive differential pressure sensor includes a flexible hose as part of the device itself, and is calibrated with the flexible hose in place (consequently, a usable hose length needs to be specified beforehand). Calibration constants for the air flow channel are determined and stored in non-volatile memory, and used to provide accurate pressure measurements. Thus, impedance in the air flow path introduced by the flexible hose is considered when the pressure sensor is calibrated. That insures that any measurement of air flow is not adversely effected by the introduction of an impedance in the air flow path previously not considered by the sensor. The present invention thus provides a self-contained differential pressure sensing device suitable for detecting changes in pressure for applications where a small amount of leakage is acceptable.
29 Citations
27 Claims
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1. A differential pressure sensor comprising:
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a fluid channeling device having a fluid channel defined therethrough and a fluid flow detector located in said fluid channel;
a circuit coupled to said fluid flow detector for detecting a change in fluid flow through said fluid channel; and
memory having stored therein a characteristic of said fluid channeling device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of calibrating a differential pressure sensor comprising the steps of:
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(a) providing a calibration system having an enclosure with a pressure chamber and a controller for controlling a pressure with the pressure chamber;
(b) coupling a pressure sensor to be calibrated to the calibration system and controller;
(c) setting a pressure within the pressure chamber;
(d) recording an output signal of the pressure sensor to be calibrated indicative of its response to the pressure set within the pressure chamber in step (c);
(e) calculating a constant for the pressure sensor to be calibrated based on the output signal recorded in step (d); and
(f) writing the constant in a memory of the pressure sensor to be calibrated. - View Dependent Claims (10)
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11. A system for controlling air flow in an enclosure having a chamber defined therein, said system comprising:
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a supply air system coupled to the chamber for providing air flow into the chamber; and
a first differential pressure sensor coupled to said supply air system and comprising;
an air channeling device having a air channel defined therethrough and a air flow detector located in said air channel;
a circuit coupled to said air flow detector for detecting a change in air flow through said air channel; and
memory having stored therein a characteristic of said air channeling device;
said first differential pressure sensor controlling said supply air system to maintain a predetermined air flow in the enclosure. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification