Flow measurement and control
First Claim
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1. An article of manufacture comprising:
- a housing;
a flow control valve contained in said housing, said flow control valve having a variable area orifice disposed within a gas flow passage and connected to an inlet portion of said passage;
a fixed area orifice disposed within said passage and connected to an outlet portion of said passage;
a first differential pressure sensor coupled across said fixed area orifice to measure a differential pressure across said fixed area orifice;
a second pressure sensor coupled to said outlet portion to measure outlet pressure; and
a circuit for producing a signal representative of a square root of a product of said differential pressure and said outlet pressure based on said first sensor and said second sensor.
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Abstract
An exhaust gas recirculation systems directs exhaust gasses from an exhaust manifold to an intake manifold of an internal combustion engine. The exhaust gasses travel from the exhaust manifold, first passing through a flow control valve and then through a measuring orifice before entering the intake manifold. Pressure difference across the orifice is used, along with correction factors based on the pressure difference and pressure downstream of the orifice, to measure and control exhaust gas flow.
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Citations
16 Claims
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1. An article of manufacture comprising:
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a housing;
a flow control valve contained in said housing, said flow control valve having a variable area orifice disposed within a gas flow passage and connected to an inlet portion of said passage;
a fixed area orifice disposed within said passage and connected to an outlet portion of said passage;
a first differential pressure sensor coupled across said fixed area orifice to measure a differential pressure across said fixed area orifice;
a second pressure sensor coupled to said outlet portion to measure outlet pressure; and
a circuit for producing a signal representative of a square root of a product of said differential pressure and said outlet pressure based on said first sensor and said second sensor.
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2. A method for measuring flow from an engine exhaust to and engine intake wherein the flow passes through a flow control valve and then a fixed area measuring orifice, the method comprising;
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measuring a pressure difference across the measuring orifice, measuring a pressure downstream of the measuring orifice representative of manifold pressure, calculating a pressure and temperature correction based on said downstream pressure and said differential pressure; and
calculating a flow based on said downstream pressure, said differential pressure, and said correction. - View Dependent Claims (3, 4, 5, 6, 7)
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8. A flow measurement system for measuring exhaust gas flow from an exhaust manifold of an internal combustion engine to an intake manifold of the engines the system comprising:
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a flow control valve having a variable orifice positioned in an exhaust gas recirculation path between the exhaust manifold and intake manifold of the engine;
a fixed orifice area located in said path and downstream of said valve; and
a computer for measuring a first pressure downstream of said fixed orifice area, measuring a differential pressure across said fixed orifice area, and calculating a mass flow based on a product of said first pressure and said differential pressure. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification