US 6,546,912 B2Granted

On-line individual fuel injector diagnostics from instantaneous engine speed measurements

AssigneeCummins Engine Company, Inc.

InventorTaner Tuken

Life of this patent

Estimating the term…

Loading patent…

Abstract

Manufacturing imperfections and component failures in the fuel system of an engine, can lead to non-uniform torque production among the cylinders. Non-uniform cylinder torques can be observed as small engine speed fluctuations about the average engine speed at any given operating point. Engine speed data contains fluctuations at different frequencies. The amplitude of fluctuations at some known frequencies tell about the health of the fuel injectors and the engine. In the present invention, the instantaneous engine speed data is filtered by discrete second-order band-pass filters to find the engine speed fluctuations at particular frequencies. The output of the filters is identical to power spectral density of speed signal at those frequencies. The amplitude of each filter output is then compared to a predetermined threshold value. If the amplitude is bigger than this threshold, it indicates the existence of low fueling or high fueling fuel injectors. If the amplitude is bigger than a second higher threshold, it indicates the existence of dead fuel injectors.

Claims43

Dependent claims

A method for cylinder balancing of an engine having a plurality of fuel injectors, comprising the steps of:

a. sensing a speed of the engine a plurality of times during a time period;
b. filtering the sensed engine speed, thereby producing engine speed fluctuation data at predetermined frequencies corresponding to respective ones of the plurality of fuel injectors;
c. comparing the filtered engine speed fluctuations to a first predetermined threshold value;
d. comparing the engine speed fluctuations to a second predetermined threshold value when the engine speed fluctuations did not satisfy the threshold conditions in step (c);
e. if the engine speed fluctuations did not satisfy the threshold conditions in step (d);
performing steps e.1 through e.4;
e.1 resetting all fuel injector trims to a predetermined value and calculating the total engine speed fluctuation;
e.2 for a first one of the plurality of fuel injectors reducing fuel injector fueling by a predetermined value and calculating a new total engine speed fluctuation;
e.3 generating a fault code for the first fuel injector when the calculated engine speed fluctuations from steps (e.1) and (e.2) are equal;
e.4 repeating steps (e.1) through (e.3) for each remaining fuel injector;
f. if the engine speed fluctuations satisfy the threshold conditions in step (d);
performing steps f.1 through f.3;
f.1 adjusting the trim for the first fuel injector and calculating the total engine speed fluctuation;
f.2 readjusting the trim for the first fuel injector until the calculated total engine speed fluctuation is at a local minimum;
f.3. repeating steps (f.1) through (f.2) for all fuel injectors;
and
g. generating fault codes corresponding to adjustments made to each of the fuel injectors.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/798,360Filed 2 Mar 2001
Published: US 2002/0148441 A117 Oct 2002
Granted: 15 Apr 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

F02D 41/0085
Controlling each cylinder individually: balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
F02D 41/1498
With detection of the mechanical response of the engine: measuring engine roughness
F02D 41/2451
Methods of calibrating or learning: characterised by what is learned or calibrated
F02D 41/2467
Characteristics of actuators: for injectors