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US 5,837,903 AGranted
Device for measuring exhaust flowrate using laminar flow element
AssigneeThe Scott Fetzer Company
InventorJack Weigand
Life of this patent
Estimating the term…
Abstract
An apparatus for determining the exhaust flowrate from an internal combustion engine (112) includes a laminar flowmeter (116). The flowmeter includes a capillary section (18) of ceramic material including an array of capillary tubes. Signals from a differential pressure sensor (128) which measures pressure loss across the capillary section as well as an absolute pressure sensor (126) and a temperature sensor (130) are input to a computer (134). The computer is programmed to calculate the flowrate of exhaust gas from the engine through its operating range.
Claims33
An apparatus for measuring the exhaust gas flowrate from an internal combustion engine comprising:
- a body in fluid communication with said engine, wherein exhaust gas is enabled to flow therethrough;
- a capillary section housed within said body, wherein pressure of said exhaust gas is reduced as it flows through said capillary section;
- a pressure differential sensor operatively connected across said capillary section, wherein said pressure sensor outputs at least one pressure signal responsive to said pressure reduction, whereby said pressure signal is usable to calculate said exhaust gas flowrate;
- a temperature sensor positioned in said exhaust gas adjacent to said capillary section, and wherein said temperature sensor outputs at least one temperature signal responsive to a temperature of said exhaust gas;
- a computer, wherein said computer is in operative connection with said temperature sensor;
- a clock in operative connection with said engine and said computer, wherein said clock is operative to measure an elapsed time from a start of said engine;
- and
- a memory in operative connection with said computer, wherein said memory contains data representative of said exhaust gas composition as a function of said elapsed time, and wherein said computer is operative to calculate a value corresponding to a viscosity of said exhaust gas as a function of said memory data and said temperature signal.
5 more elements
A method for measuring the volumetric flowrate of exhaust gas from an internal combustion engine comprising the steps of:
- placing a laminar flow element in fluid communication with an exhaust conduit of said engine, wherein said laminar flow element comprises a body, and a capillary section located within said body, wherein said exhaust gas flows therethrough,
- placing a pressure differential sensor in fluid communication with said laminar flow element at both an upstream side of said capillary section and at a downstream side of said capillary section, and generating at least one signal with said pressure differential sensor, said signal representative of the pressure difference in the exhaust gas on said sides of said capillary section,
- placing an absolute pressure sensor in fluid communication with said laminar flow element on said upstream side of said capillary section, and generating at least one signal with said absolute pressure sensor, said signal representative of the pressure of said exhaust on said upstream side of said capillary section,
- placing a temperature sensor in operative connection with said exhaust gas flowing through said laminar flow element, and generating at least one signal with said temperature sensor, said signal representative of said exhaust gas temperature;
- starting said engine,
- calculating with a computer said exhaust gas flowrate as a function of at least one of said signals;
- starting a timer when said engine is started, and generating a signal representative of the elapsed time from said starting step;
- sampling with said computer said time signal at predesignated times while said engine is running,
- wherein said calculating step is repeated at each predesignated time, wherein said computer has a memory in connection therewith, and wherein said memory has stored therein exhaust gas composition data, and wherein in said calculating step said computer calculates said exhaust gas flow rate as a function of at least said one of said signals and said composition date.
6 more elements
A method for determining an exhaust gas flowrate from an internal combustion engine, comprising the steps of:
- passing exhaust gas from an internal combustion engine through a laminar flow element having a capillary section, wherein said exhaust gas is in a laminar flow condition;
- sensing with a differential pressure sensor a pressure drop for said exhaust gas passing through said capillary section;
- generating at least one differential pressure signal responsive to said pressure drop;
- sensing temperature of said exhaust gas adjacent said capillary section and generating at least one temperature signal responsive to said temperature;
- sensing absolute pressure on an upstream side of said capillary section and generating at least one absolute pressure signal corresponding to said absolute pressure;
- and
- calculating said exhaust gas flowrate with a computer, wherein said computer is in operative connection with a memory and wherein said memory has stored therein exhaust gas composition data as a function of time from an engine start, and wherein said passing step commences with the start of said engine, and further comprising starting an elapsed timer at said engine start, and calculating with said computer values corresponding to viscosity and density of said exhaust gas responsive to said temperature signal, said absolute pressure signal and said exhaust gas composition data in said memory, wherein said computer calculates said exhaust gas flowrate responsive to said calculated viscosity and density values and said differential pressure signal.
4 more elements
Dependencies are inferred from the claim text.