Method and apparatus for measuring evaporative emissions in a fixed-volume enclosure

• US 5,526,675 A
• Filed: 12/06/1994
• Issued: 06/18/1996
• Est. Priority Date: 04/26/1993
• Status: Expired due to Fees

• Current Assignee: Power-Tek, Inc. (Illinois Tool Works Inc.)
• Original Assignee: Power-Tek, Inc. (Illinois Tool Works Inc.)
• Inventors: Ratton, Kenneth
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): Dombroske, George M.
• Application Number:
  US08/349,809
• Time in Patent Office: 560 Days
• Field of Search: 73/118.1, 73/116, 73/23.2, 73/23.31, 73/23.35, 73/40, 73/49.7
• US Class Current: 73/23.2
• CPC Class Codes: G01M 17/007 Wheeled or endless-tracked vehicles G01M17/08 takes precedence
• CPC Class Codes: G01N 33/0016 by regulating a physical variable, e.g. pressure or temperature
• CPC Class Codes: G01N 33/2852 Alcohol in fuels

Abstract

Provided is a method and apparatus for measuring evaporative vehicle emissions in a fixed-volume enclosure. The method comprises the steps of providing a volume compensation means in fluid communication with a test chamber for compensating for changes in the test chamber fluid volume, where n is a positive integer, measuring the temperature of the test chamber fluid at the sample times t_n, measuring the absolute fluid pressure of fluid at the sample times t_n, determining the density of the evaporative emissions and the test chamber fluid at selected sample times t_n, determining the mass of evaporative emissions present in the chamber, determining the theoretical volume change of the test chamber fluid at said sample times t_n in accordance with the Ideal Gas Law (PV=nRT), determining the mass of the evaporative emissions in aspirated volume, summing the determined masses of the evaporative emissions to provide a calculation of the evaporative emissions aspirated by the volume compensation means during expansion of the test chamber fluid, and summing this with the final sample mass to determine the total evaporative emissions from a vehicle. In an alternative embodiment, a plurality of impingers are also provided for use in determining the aspirated mass of alcohol emissions in flexible fueled vehicles.

Claims

1. A leak-tolerant method of measuring evaporative emissions in a fixed volume test chamber filled with a fluid having a predetermined mass of evaporative emissions M₁, chamber volume, temperature and pressure at time t₀ and a determined mass (M_n) of evaporative emissions at a reading t_n, comprising the steps of:

providing volume compensation means in fluid communication with said test chamber for compensating for changes in said test chamber fluid volume;

measuring the temperature of said test chamber fluid at said sample times t_n ;

measuring the absolute fluid pressure of said test chamber at said sample times t_n ;

determining the mass of evaporative emissions present in the chamber;

determining the density of said evaporative emissions in said test chamber fluid in mass per unit volume at selected sample times t_n, where n is a positive integer;

determining the theoretical volume change of said test chamber fluid at said sample times t_n in accordance with the Ideal Gas Law (PV=nRT);

determining the aspirated mass of said evaporative emissions in M_asp(n) ;

summing the determined masses of said evaporative emissions M_asp(n) to provide a calculation of the total evaporative emissions aspirated by said volume compensation means during expansion of said test chamber fluid, (Σ

M_asp(n)); and

summing (Σ

M_asp(n)) and M_n, and subtracting M₁ to determine a total mass of evaporative emission.