METHOD FOR ANALYZING INJECTOR PERFORMANCE

• US 20150149063A1
• Filed: 11/25/2013
• Published: 05/28/2015
• Est. Priority Date: 11/25/2013
• Status: Active Grant

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Shah, Nirav Atul, Michelotti, Mark Brian, Yerunkar, Sumeet Suresh
• Granted Patent: US 9,605,611 B2
• Time in Patent Office: Days
• US Class Current: 701/104
• CPC Class Codes: F02D 2200/101 Engine speed
• CPC Class Codes: F02D 2200/1012 Engine speed gradient
• CPC Class Codes: F02D 41/0085 Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• CPC Class Codes: F02D 41/0097 using means for generating speed signals
• CPC Class Codes: F02D 41/1498 measuring engine roughness
• CPC Class Codes: F02D 41/2467 for injectors
• CPC Class Codes: F02D 41/40 with means for controlling injection timing or duration
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Injector drift for a diesel engine are detected by reconfiguration of injection patterns from one pattern into a pattern with a different number of pulse points while attempting to hold total fuel injected constant. If a particular injector is subject to drift then changes in the pulse pattern result in an increase or decrease in fuel injected and consequential variations in engine speed. By applying alternating injection patterns at constant fuel demand and allowing engine speed time to stabilize, a rhythmic variation in engine speed/torque will appear which can be detected using one of a number of techniques.

Claims

1. A method for detecting injector drift on an internal combustion engine, the method comprising the steps of:

establishing at least first and second patterns of fuel injection pulses for application to a cylinder of the internal combustion engine with the first and second patterns differing in number of fuel injection pulses while having the same nominal target amount of fuel to deliver;

operating the engine at a target level steady state condition with the injectors for all cylinders being active;

selecting at least a first cylinder to test;

injecting fuel to the selected cylinder using each of the first and second patterns at least once during a period; and

determining if engine speed varies with correlation to the predetermined sequence.

2. The method of claim 1, wherein the internal combustion engine is a four cycle diesel engine, the step of injecting fuel involving alternating between the first and second patterns and engine speed varies with a one quarter order of engine crankshaft angular position.

3. The method of claim 2, the step of injecting fuel continuing until the frequency components of engine speed have stabilized.

4. The method of claim 1, further comprising the steps of:

deselecting the currently selected cylinder; and

repeating the last three steps of claim 1.

5. The method of claim 4 where the first pattern comprises a plurality of injection pulses and the second pattern comprises a single injection pulse.

6. A method of evaluating internal combustion engine fuel injector operation, the method comprising the steps of:

operating the internal combustion engine at idle;

selecting at least a first injector for evaluation;

changing the number of injection pulses from the injector or injectors under evaluation on a periodic basis over a period of time without changing the target amount of fuel to inject;

monitoring engine crankshaft speed over the period of time; and

determining from engine crankshaft speed if a frequency order signal corresponding to the periodicity of the step of changing appears.

7. The method of claim 6, further comprising the steps of:

absent determination of appearance of the frequency order signal corresponding to the periodicity of the step of changing further determining that the injector or injectors under evaluation are not drifting.

8. The method of claim 6, further comprising the steps of:

upon determination of appearance of the frequency order signal corresponding to the periodicity of the step of changing further determining that one or more of the injector or injectors under evaluation is drifting.

9. A fuel injection system for an internal combustion engine, the system comprising:

a crankshaft position indicator;

at least a first fuel injector;

a fuel injector controller allowing selection of the number of injection pulses and control of injection pulse width for the at least first fuel injector;

means for monitoring engine crankshaft speed over the period of time; and

means responsive to periodic variation in the number of injection pulses within a period of time for determining from engine crankshaft speed if a frequency order signal corresponding to the periodicity appears.