Abstract: An engine exhaust flow meter and method of measuring engine exhaust flow rate includes a flow tube and a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube. A computer samples the differential pressure meter at a rate that is greater than the pulsation of exhaust flow to obtain a differential pressure signal. The computer is responsive to the differential pressure signal to compute a mean differential pressure value. The computer is responsive to the differential pressure signal to compute a mean magnitude of pressure pulses. The computer determines a compensation factor as a function of the mean magnitude of pressure pulses and adjusts the mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.

Abstract: An engine exhaust flow meter and method of measuring engine exhaust flow rate includes a flow tube and a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube. A computer samples the differential pressure meter at a rate that is greater than the pulsation of exhaust flow to obtain a differential pressure signal. The computer is responsive to the differential pressure signal to compute a mean differential pressure value. The computer is responsive to the differential pressure signal to compute a mean magnitude of pressure pulses. The computer determines a compensation factor as a function of the mean magnitude of pressure pulses and adjusts the mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.

Abstract: A vehicle gas emission analyzer assembly for a vehicle having a passenger compartment includes a gas analyzer system adapted to determine concentration and/or mass flow of at least one exhaust gas of an internal combustion engine. The analyzer may include a particular housing for the gas analyzer system. The gas analyzer system may include a hydrocarbon gas analyzer that is operated at a temperature that is sufficiently high to reduce deposits of hydrocarbon molecules present in the sample gas. The gas analyzer may include an ultraviolet source including a discharge lamp having a discrete emission line at an absorption frequency for a particular nitrogen-based gas.

Abstract: A method and apparatus for measuring vehicle exhaust emission includes sampling vehicle exhaust and a dilute mixture of vehicle exhaust and ambient air. A first analyzer measures concentrations of gas components of undiluted vehicle exhaust. A second analyzer measures concentration of at least one exhaust gas component present in the dilute mixture gas component. The at least one dilute mixture gas component is a particular exhaust gas component measured by the first analyzer which is also present in ambient air in substantial quantity. Flow rate of the dilute mixture, the concentration of the at least one dilute mixture gas component and undiluted gas concentration are analyzed by a microprocessor to produce mass emissions of the vehicle exhaust gas components.