公开(公告)号：US3603155A

公开(公告)日：1971-09-07

申请号：US3603155D

申请日：1970-02-02

Applicant: CHROMALLOY AMERICAN CORP

Inventor： MORRIS CHARLES WILLIAM ,  ULYATE JOHN RAYMOND

IPC: G01M15/10 ,  G01N1/22 ,  G01N33/00

CPC classification number: G01N33/0011 ,  G01M15/102 ,  G01N1/2247 ,  Y10S55/30

Abstract: An air blower draws a mixture of exhaust gases emitted from an internal combustion engine and ambient air through a through-flow duct having a valve means therein at a minimum volumetric flow rate for the mixture in excess of the maximum volumetric flow rate the engine is capable of emitting while a proportional sample of said total mixture is withdrawn into a sample container at a uniform volumetric rate during a test period, the sample thereafter being analyzed to determine the concentration of pollutants of gas constituents therein and compared with the concentration of such pollutants or gas constituents in the ambient air which is sampled concurrently at the same flow rate from an area adjacent that where the ambient air is drawn into the through-flow conduit, total mass or weight of such pollutants or constituents being calculable from the concentration thereof in said sample and the known total mass or weight of air and gas mixture drawn through the duct. Temperature sensing and transducer means produce a first or error signal which is a function of the temperature of gases flowing through said duct, volumetric flow rate sensing means and associated transducer means produce a second signal which is a function of volumetric gas flow through the duct and electrical circuit means are provided in association therewith to cause said second signal to modify said first signal to produce a control signal which causes operation of a servomotor to adjust the valve means until an actual required volumetric flow rate through the duct is attained for any given temperature thereof to maintain a constant mass or weight flow, said actual volumetric flow rate for said gases increasing with increasing gas temperatures above a standard initial flow rate for a standard temperature condition. Circuitry is provided for a system for maintaining constant the rate of mass flow of a gas through a conduit despite temperature changes. The system generates an error signal linear with the absolute temperature of the gas, generates a second signal which is linear with differential pressure across a fixed orifice in the conduit, and thus with velocity of flow therein, modifies the error signal by the second signal to produce a command signal of appropriate polarity to adjust the velocity of gas flow in an inverse feedback manner by controlling a throttling valve in the conduit.