Method and device for regulating the NO.sub.x emission of an internal combustion engine

• US 5,657,732 A
• Filed: 01/17/1996
• Issued: 08/19/1997
• Est. Priority Date: 01/27/1995
• Status: Expired due to Term

• Current Assignee: Deltec Fuel Systems BV
• Original Assignee: Deltec Fuel Systems BV
• Inventors: Lugtenburg, Johan, Wolters, Leendert
• Primary Examiner(s): ARGENBRIGHT, TONY MICHAEL
• Application Number:
  US08/587,979
• Time in Patent Office: 580 Days
• Field of Search: 123/435, 123/436, 123/478, 123/480, 123/486, 123/527
• US Class Current: 123/436
• CPC Class Codes: F02D 19/023 to adjust the fuel mass or volume flow
• CPC Class Codes: F02D 19/028 by estimation, i.e. without using direct measured parameter of a corresponding sensor
• CPC Class Codes: F02D 35/02 on interior conditions
• CPC Class Codes: F02D 35/026 using an estimation
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/0027 the fuel being gaseous non-electrical control F02D19/02
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

Method and device for regulating the NO_x emission of an internal combustion engine. It has been found that the NO_x emission is dependent on the efficiency of the engine. That is to say the NO_x emission can be optimized by determining and controlling the efficiency. This can be performed by making the measured and determined efficiencies equal to one another by altering the air/fuel ratio.

Claims

1. Method for regulating an internal combustion engine by adjusting of an air/fuel ratio as a function of operating conditions of said engine, the output of said engine being measured, said method comprising:

determining a desired efficiency of said engine under said operating conditions;

measuring an efficiency under said operating conditions, and

altering the air/fuel ratio of an air/fuel mixture in such a way that the desired and measured efficiencies are equal, the air/fuel ratio being reduced if the measured efficiency is higher than the desired efficiency.

2. Method according to claim 1, wherein said determining step further includes providing a table in which the desired efficiency is stored as a function of output, and also determining the output.

3. Method according to claim 1, wherein said altering step keeps the output of said engine constant.

4. Method according to claim 1, wherein said altering step keeps the measured efficiency of said engine essentially constant.

5. Method according to claim 3, further comprising the consecutive steps of, under varying operating conditions,

a) changing the mixture flow to keep the output constant,

b) measuring the efficiency and comparing the measured efficiency with the desired efficiency and

c) adapting the air/fuel ratio accordingly, optionally followed by repetition of steps a-c.

6. Method according to claim 5, wherein a rate of alteration in step a) is at least ten times as great as a rate of alteration in step c).

7. Method according to claim 1, wherein said air/fuel ratio altering step comprises a step of changing of a quantity of gas introduced.

8. Method according to claim 1, wherein said measuring step comprises a step of calculating the gas flow.

9. Method according to claim 8, wherein said calculating step comprises a step of measuring the air flow.

10. Method according to claim 8, wherein said calculating step comprises a step of measuring or determining at least one of the following parameters:

manifold pressure, manifold temperature, the speed of the engine, the volumetric efficiency and the stroke volume.

11. Device for regulating a combustion engine comprising means for measuring the engine output, memory storage means, comparison means, computing means and also means for changing an air/fuel ratio controlled by the comparison means, wherein

the memory storage means stores a desired efficiency of said engine,

the computing means determine a measured efficiency as a function of a quantity of air/fuel mixture introduced and

the comparison means become operative in the event of a difference between said measured and said desired efficiencies.

12. Device according to claim 11, wherein the memory storage means store a table in which the desired efficiency is stored as a function of an output.

13. Device according to claim 11, further comprising means for maintaining an engine output constant.

14. Device according to claim 11, further comprising means for determining an instability of the engine.