Method and apparatus for performing modal mass analysis of exhaust gas from motor vehicle

• US 5,639,957 A
• Filed: 10/12/1995
• Issued: 06/17/1997
• Est. Priority Date: 10/12/1995
• Status: Expired due to Term

• Current Assignee: Richard R. Zarchy, Snap-On Technologies Incorporated (Snap-On Incorporated)
• Original Assignee: Snap-On Technologies Incorporated (Snap-On Incorporated)
• Inventors: Zarchy, Richard R.
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US08/542,064
• Time in Patent Office: 614 Days
• Field of Search: 73/23.31, 73/23.32, 73/116, 73/117, 73/117.2, 73/117.3, 73/118.1, 60/273, 60/276
• US Class Current: 73/23.31
• CPC Class Codes: G01M 15/102 by monitoring exhaust gases

Abstract

A method and apparatus for measuring the quantity of an ingredient gas in the exhaust gas from a motor vehicle with a known engine displacement during a time period in which the vehicle is driven over varying driving modes (modal mass analysis). The resultant measurement is achieved without use of a constant volume sampling device by first measuring and storing data C_E (t) representative of the concentration of the ingredient gas in the exhaust gas at successive time intervals during the period. The vehicle speed during each successive time interval is measured and stored, followed by calculating theoretical exhaust flow rate values Q_Ei (t), representative of the flow rate of the exhaust gas for each of the succession of time intervals, based on the known engine displacement and the measured engine speed. Then approximate actual exhaust flow rate values Q_Ea (t) are calculated using a polynomial curve fit method on the calculated theoretical flow rate values Q_Ei (t). Lastly, the quantity M(t) of the ingredient gas in the exhaust gas for each of the succession of time intervals is determined on the basis of the operational equation

M(t)=ρ×C.sub.E (t)×Q.sub.Ea (t),

where ρ is the density of the ingredient gas.

Claims

1. A method of determining flow rate of exhaust gas from a motor vehicle with a known engine displacement, the method comprising the steps of:

measuring and storing the engine speed;

calculating a theoretical exhaust flow rate value Q_Ei, representative of the theoretical flow rate of the exhaust gas, based on the known engine displacement and the measured engine speed; and

calculating an approximate actual exhaust flow rate value Q_Ea on the basis of a polynomial curve expression relating to the calculated theoretical flow rate value Q_Ei.

2. The method of claim 1, wherein said polynomial curve expression is defined by the following operational equation:

##EQU2## where C₁, C₂ and C₃ are constants.

3. The method of claim 2, wherein C₁ is a constant of value 1.06764×

10², C₂ is a constant of value 3.11868×

10^-1, and C₃ is a constant of value 1.24765×

10¹.

4. The method of claim 1, wherein said calculated actual flow rate value Q_Ea is stored in a memory register.

5. A method of measuring the quantity of an ingredient gas in the exhaust gas from a motor vehicle with a known engine displacement during a time period in which the vehicle is driven over varying driving modes, the method comprising the steps of:

measuring and storing data C_E (t) representative of the concentration of the ingredient gas in the exhaust gas at successive time intervals during said period;

measuring and storing the vehicle engine speed during each said successive time interval;

calculating theoretical exhaust flow rate values Q_Ei (t), representative of the flow rate of the exhaust gas for each of the succession of time intervals, based on the known engine displacement and the measured engine speed;

calculating approximate actual exhaust flow rate values Q_Ei (t) using a polynomial curve fit method on the calculated theoretical flow rate values Q_Ei (t); and

determining the quantity M(t) of the ingredient gas in the exhaust gas for each of the succession of time intervals on the basis of the operational equation

space="preserve" listing-type="equation">M(t)=ρ

×

C.sub.E (t)×

Q.sub.Ea (t),

where ρ

is the density of the ingredient gas.

6. The method of claim 5, wherein said polynomial curve expression is defined by the following operational equation:

##EQU3## where C₁, C₂ and C₃ are constants.

7. The method of claim 6, wherein C₁ is a constant of value 1.06764×

10², C₂ is a constant of value 3.11868×

10^-1, and C₃ is a constant of value 1.24765×

10¹.

8. The method of claim 5, wherein said calculated actual flow rate value Q_Ea is stored in a memory register.

9. An apparatus for determining a flow rate of exhaust gas from a motor vehicle with a known engine displacement, the apparatus comprising:

means for measuring and storing the engine speed;

means for calculating a theoretical exhaust flow rate value Q_Ei, representative of the theoretical flow rate of the exhaust gas, based on the known engine displacement and the measured engine speed; and

means for calculating an approximate actual exhaust flow rate value Q_Ea on the basis of a polynomial curve expression relating to the calculated theoretical flow rate value Q_Ei.

10. The apparatus of claim 9, wherein said means for calculating the approximate actual flow value Q_Ea includes means for converting the theoretical value Q_Ei to the approximate actual value Q_Ea on the basis of the following operational equation:

##EQU4## where C₁, C₂ and C₃ are constants.

11. The apparatus of claim 10, wherein C₁ is a constant of value 1.06764×

10², C₂ is a constant of value 3.11868×

10^-1, and C₃ is a constant of value 1.24765×

10¹.

12. An apparatus for determining a quantity of an ingredient gas in the exhaust gas from a motor vehicle with a known engine displacement during a time period in which the vehicle is driven over varying driving modes, the method comprising the steps of:

means for measuring and storing data C_E (t) representative of the concentration of the ingredient gas in the exhaust gas at successive time intervals during said period;

means for measuring and storing the vehicle speed during each said successive time interval;

means for calculating theoretical exhaust flow rate values Q_Ei (t), representative of the flow rate of the exhaust gas for each of the succession of time intervals, based on the known engine displacement and the measured engine speed;

means for calculating approximate actual exhaust flow rate values Q_Ea (t) on the basis of a polynomial curve expression relating to the calculated theoretical flow rate values Q_Ei (t); and

means for determining a quantity M(t) of the ingredient gas in the exhaust gas for each of the succession of time intervals on the basis of the operational equation

space="preserve" listing-type="equation">M(t)=ρ

×

C.sub.E (t)×

Q.sub.Ea (t),

where ρ

is the density of the ingredient gas.

13. The apparatus of claim 12, wherein said means for calculating approximate actual flow value Q_Ea (t) includes means for converting theoretical values Q_Ei (t) to approximate actual values Q_Ea (t) on the basis of the following operational equation:

##EQU5## where C₁, C₂ and C₃ are constants.

14. The apparatus of claim 13, wherein C₁ is a constant of value 1.06764×

10², C₂ is a constant of value 3.11868×

10^-1, and C₃ is a constant of value 1.24765×

10¹.