Method and apparatus for determining emission measurement accuracy

• US 5,717,130 A
• Filed: 08/23/1996
• Issued: 02/10/1998
• Est. Priority Date: 08/23/1996
• Status: Expired due to Fees

• Current Assignee: Bombardier Recreational Products Incorporated (Bombardier Incorporated)
• Original Assignee: Outboard Marine Corporation (Bombardier Incorporated)
• Inventors: Rush, William B., Xu, Y. Ron
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/704,219
• Time in Patent Office: 536 Days
• Field of Search: 73/23.31, 73/117.3, 340/439
• US Class Current: 73/23.31
• CPC Class Codes: G01N 33/0014 by eliminating a gas by a chemical reaction G01N33/0013; a chemical reaction taking place or a gas being eliminated in one or more analysing channels G01N33/0024
• CPC Class Codes: G01N 33/0016 by regulating a physical variable, e.g. pressure or temperature

Abstract

Methods and apparatus for determining and assessing the accuracy of exhaust gas measurements using the total emission method is provided which allows for virtually real-time determination of the presence of a source of inaccuracy in the total emission measurement, thereby notifying an operator to interrupt the test prior to its completion to search out the source of the inaccuracy. In accordance with one aspect of the present invention, the measured total hydrocarbons are treated as unburned fuel (C₈ basis) plus burning zone hydrocarbons (C₁ basis).

Claims

1. A method of assessing the accuracy of determinations of the total emissions from an internal combustion engine, the method comprising:

measuring the volumetric percentages of CO, CO₂, O₂, NO_x, and HC present in the exhaust emissions from the internal combustion engine over a selective period of time;

averaging the respective volumetric percentages for each of said emission constituents over said selective period of time;

measuring the fuel flow rate over said selective period of time;

determining unburned fuel (C₈) mole percentage and burning zone HC (C₁) mole percentage present in said emissions from said internal combustion engine;

averaging the fuel flow rate over said selective period of time;

repeatedly calculating the total percentage emission utilizing the averaged data of CO, CO₂, O₂, NO_x, HC and the fuel flow rate;

determining an acceptable accuracy range;

comparing each of said repeatedly calculated total percentage emissions to said accuracy range; and

automatically actuating a warning indicia upon a calculated total percentage emission falling outside of said accuracy range.

2. The method in accordance with claim 1 in which said step of determining unburned fuel (C₈) mole percentage and burning zone HC (C₁) mole percentage present in said emissions from said internal combustion engine comprises utilization of the following formulae:

##EQU11## where;

Q=Fuel flow rate, g/hr!;

HC_ppmC1 =Measured total HC emission, ppmC₁ ; and

W_HC =Average mass flow rate of HC emission, g/hr!, which may be calculated by using the formula;

##EQU12##

3. The method in accordance with claim 1 further comprising interrupting the emission measurement if the calculated total percentage emission exceeds said set accuracy limit.

4. The method in accordance with claim 1 in which the step of calculating the total percentage emission is carried out automatically by one or more processors.

5. The method in accordance with claim 1 in which each of said averaging, calculating and comparing steps is carried out automatically by a processor.

6. The method in accordance with claim 1 in which said accuracy range comprises (100%)±

(a predetermined multiple of the standard deviation of all previous total emission calculations).

7. The method in accordance with claim 5 in which said accuracy range comprises (100%)±

(two standard deviations of all previous total emission calculations).

8. The method in accordance with claim 1 in which said set accuracy limit is initially preset as 100%±

3, and the mean and standard deviation of the total percentage emission are automatically calculated over a predetermined number of said repeatedly calculated total percentage emission determinations, and the accuracy limit is reset upon attainment of said predetermined number as (said mean)±

(double said standard deviation).

9. The method in accordance with claim 1 further including automatically actuating said warning indicia upon the mean of the total percentage emission calculations falling outside of the range of 100%±

1.

10. A method of assessing the accuracy of determinations of the total emissions from an operating internal combustion engine, the method comprising:

repeatedly measuring the quantity of each of CO, CO₂, O₂, NO_x, and HC present in the exhaust emissions of the internal combustion engine over a selective period of time;

generating electrical signals representative of the respective quantities of each of said CO, CO₂, O₂, NO_x, and HC components measured in said exhaust emissions;

repeatedly measuring the fuel flow rate during said selective period of time;

generating electrical signals representative of the fuel flow rate;

operatively coupling a processor to said electrical signals for receiving said electrical signals;

carrying out pre-programmed calculations on the processor of the averages of each of said respective emission components and fuel flow rate over said selective period of time;

repeatedly calculating the total percentage emission utilizing the averaged data of CO, CO₂, O₂, NO_x, HC and the fuel flow rate;

determining an acceptable accuracy range;

comparing each of said repeatedly calculated total percentage emissions to said accuracy range; and

automatically actuating a warning indicia upon a calculated total percentage emission falling outside of said accuracy range.

11. A method in accordance with claim 10 in which the step of determining an acceptable accuracy range comprises repeatedly redefining said accuracy range upon each calculation of the total percentage emission.

12. A method in accordance with claim 11 in which the step of determining an acceptable accuracy range comprises repeatedly calculating the standard deviation of the calculated total percentage emissions and setting the range as 100%±

double the calculated standard deviation at that point in time.

13. A method in accordance with claim 10 further comprising automatically interrupting said exhaust component and fuel flow rate measurements upon a calculated total percentage emission falling outside of said accuracy range.

14. An emission testing apparatus for determining the accuracy of emission measurements of the exhaust from an internal combustion engine, the apparatus comprising:

a housing defining a passage for directing the emissions of said internal combustion engine

a CO sensor mounted in said housing passage for measuring the mount of CO in the emissions of said internal combustion engine over a selective period of time;

a CO₂ sensor mounted in said housing passage for measuring the amount of CO₂ in the emissions of said internal combustion engine over said selective period of time;

an O₂ sensor mounted in said housing passage for measuring the amount of O₂ in the emissions of said internal combustion engine over said selective period of time;

a NO_x sensor mounted in said housing passage for measuring the amount of NO_x in the emissions of said interval combustion engine over said selective period of time;

a HC sensor mounted in said housing passage for measuring the amount of HC in the emissions of said internal combustion engine over said selective period of time;

a fuel flow rate sensor operatively connectable to said internal combustion engine for measuring the mount of fuel supplied to said internal combustion engine over said selective period of time;

means for transmitting electrical data representative of the measured amounts of CO, CO₂, O₂, NO_x, HC, and fuel flow rate;

a warning indicia attached to said housing;

an electronic processor, said processor comprising;

means for receiving said data representative of the measured amounts of CO, CO₂, NO_x, HC, and fuel flow rate;

means for calculating the averages of the respective amounts of CO, CO₂, O₂, NO_x, hydrocarbons, and fuel flow rate over said selective period of time;

means for repeatedly calculating the total percentage emission utilizing the averaged data of CO, CO₂, O₂, NO_x, hydrocarbons and the fuel flow rate;

means for calculating a predetermined acceptable accuracy range for said calculated total percentage emissions;

means for comparing each of said repeatedly calculated total percentage emissions to said calculated accuracy range; and

means for automatically actuating said warning indicia upon one of said calculated total percentage emissions falling outside of said calculated acceptable accuracy range.

15. An emission testing apparatus in accordance with claim 14 in which said means for repeatedly calculating the total percentage emission utilizing the averaged data of CO, CO₂, O₂, NO_x, hydrocarbons and the fuel flow rate comprises utilization of the following formulae for determining the amount of hydrocarbons:

##EQU13## where Q=Fuel flow rate, g/hr!;

HC_ppmC1 =Measured total HC emission, ppmC₁ ; and

W_HC =Average mass flow rate of HC emission, g/hr!, which may be calculated by using the formula;

##EQU14##

16. An apparatus in accordance with claim 14 in which said means for calculating a predetermined acceptable accuracy range comprises repeatedly calculating the standard deviation of the calculated total percentage emissions and setting the range as 100%±

double the calculated standard deviation at that point in time.

17. An apparatus in accordance with claim 14 in which the apparatus further comprises a video screen operatively coupled to said electronic processor, and said electronic processor further comprises means for effecting a visual display of the calculated total emissions and the calculated acceptable accuracy range on said video screen.