Method and system for vehicle emission testing

• US 6,623,975 B1
• Filed: 05/08/2001
• Issued: 09/23/2003
• Est. Priority Date: 05/09/2000
• Status: Expired due to Fees

• Current Assignee: Gordon-Darby Systems Incorporated (Opus Group AB)
• Original Assignee: Gordon-Darby Systems Incorporated (Opus Group AB)
• Inventors: Gordon, S. Jay, Tefft, Robert J., Mahaffey, Clifton
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): SINES, BRIAN J
• Application Number:
  US09/851,192
• Time in Patent Office: 868 Days
• Field of Search: 436/137, 436/127, 73/233.1, 731/16
• US Class Current: 436/137
• CPC Class Codes: G01M 15/102 by monitoring exhaust gases
• CPC Class Codes: Y10T 436/20 Oxygen containing
• CPC Class Codes: Y10T 436/208339 Fuel/air mixture or exhaust gas analysis

Abstract

A method and system for vehicle emission testing measures pollutant concentration, but then provides for conversion of the measured pollutant concentration into its corresponding pollutant mass, thereby allowing for the calculation of a vehicle'"'"'s emission test scores for one or more common pollutants in units of mass per distance. Through the use of the method and system of the present invention, significantly more accurate results can be obtained as compared to prior art test methods, and without the implementation, operating, and maintenance costs of comparable test methods.

Claims

1. A method for determining the mass of a pollutant in an emissions sample obtained form a particular vehicle to ascertain whether such pollutant mass exceeds a defined standard, comprising the steps of:

extracting the emissions sample from the particular vehicle as it is operated over a testing period comprised of a plurality of discrete time intervals;

deriving a standard exhaust flow factor from a reference data set at each discrete time interval for the particular vehicle based on certain vehicle attributes;

analyzing the emissions sample extracted from the particular vehicle to measure the concentration of the pollutant in said sample at each discrete time interval; and

determining the mass of the pollutant at each discrete time interval by multiplying the standard exhaust flow factor by the measured concentration of the pollutant by the known density of the pollutant.

2. A method as recited in claim 1, and further comprising the steps of:

plotting the mass of the pollutant over the testing period to generate an emission profile; and

integrating the emission profile over the testing period to determine the total mass of the pollutant.

3. A method as recited in claim 2, and further comprising the steps of:

dividing the total mass of the pollutant by the distance traveled over the testing period to calculate a test score for the pollutant; and

comparing said test score against a defined standard, wherein a test score exceeding the defined standard is considered a failure.

4. A method as recited in claim 1, in which the derivation of the standard exhaust flow factor comprises the following sub-steps:

characterizing the reference data set, which is comprised of a plurality of actual emission testing records based on the certain vehicle attributes, placing each testing record into at least one reference data subset defined by pre-selected vehicle attributes;

selecting a reference data subset based on the vehicle attributes of the particular vehicle from which the emissions sample is extracted;

determining a dilution factor and a diluted pollutant concentration for each data point in the reference data subset, each said data point corresponding with a discrete time interval of the testing period for the particular vehicle from which the emissions sample is extracted;

determining a raw pollutant concentration for each data point in the reference data subset by multiplying the dilution factor by the diluted pollutant concentration; and

determining the standard exhaust flow factor for the pollutant for each data point in the reference data subset, which is a function of the raw pollutant concentration, a standard density factor, and the actual measured mass of the pollutant as provided through the reference data set.

5. A method as recited in claim 1, in which the extraction and analysis of the emissions sample from the particular vehicle is accomplished by:

a narrow sample probe for insertion into the tailpipe of the particular vehicle;

a sampling line operably connected to said sample probe; and

an analyzer for detection of the pollutant associated with and in gaseous communication with a sample and calibration gas control system, said control system being operably connected to the sampling line.

6. A method as recited in claim 1, in which the certain vehicle attributes are selected from a group that includes:

make, model, year, manufacturer, inertia weight, and engine displacement.