Automated electronic trim for a fuel injector

Details Automated electronic trim for a fuel injector Automated electronic trim for a fuel injector

2001-12-18

2003-07-08

Solis, Erick (Department: 3747)

Internal-combustion engines

Combustion chamber means having fuel injection only

Using multiple injectors or injections

C123S490000, C701S114000, C073S114220

Reexamination Certificate

active

06588398

ABSTRACT:

TECHNICAL FIELD
The present invention is directed to a fuel control system and specifically to a method and apparatus for trimming a multiple injection fuel injector.
BACKGROUND
Emissions continue to drive fuel injector design and performance. As emissions standards continue to increase it becomes ever more important to control the fuel injector and the quantity of fuel being injected with great precision; however, precise control of injectors is difficult because manufacturing variation and wear can make each injector operate slightly different. In other words, although two injectors may receive the same injection signal, they may inject different amounts of fuel. This can then change expected combustion performance and generate more emissions than desired.
One method to overcome injector to injector variation has been to trim individual injectors. In one method of trimming, an injector's performance profile is determined after assembly and prior to installation in an engine. The performance profile is then provided to the engine's electronic control module (ECM), which takes that performance profile in to account when sending signals to the injector. The problem with this type of trimming is that it does not account for wear variations after the injector has been in use for a period of time. In another method of trimming, disclosed in U.S. Pat. No. 6,189,378 B1, to Kendrick et al., an injector can be trimmed in an engine by using a cylinder cut out method. In this method, one injector is shut off completely during engine operation, and its fuel delivery is determined by examining what the other injectors needed to do to compensate for the loss of the one injector. Although this exemplary method of trimming provides good results, injection schemes have become more complicated. Specifically, injectors are now injecting several times during an engine cycle and it is necessary to trim each injection event but the cylinder cut out method completely suspends the injector and therefore, individual injection events by the injector can not be distinguished.
The present invention is directed to overcoming one or more of the problems set forth above.
SUMMARY OF THE INVENTION
In one embodiment of the present invention, a method of trimming a fuel injector comprises the steps of determining a first fuel quantity to be delivered by a plurality of fuel injectors, delivering fuel injection signals to the plurality of injectors delivering a first fuel quantity wherein at least one of the plurality of injectors receives multiple injection segment signals per engine cycle, partially suspending fuel delivery by one of the plurality of injectors receiving multiple injection segment signals by suspending at least one of the multiple injection segment signals, determining the second fuel quantity to be delivered by the plurality of injectors in response to the suspending step, and determining a performance characteristic of the partially suspended injector in response to the first and second fuel quantities.
In the second embodiment of the present invention, a method of trimming fuel injectors comprises the steps of: injecting in a first mode wherein each injector receives a specific first quantity of fuel, determining a first total quantity of fuel injected by the plurality of injectors, selecting one injector from the plurality of injectors and injecting in the second mode, wherein the specific second quantity of fuel is less than the specific first quantity of fuel, determining a second total quantity of fuel injected by the plurality of injectors in response to the selected step, and determining a performance characteristic of said selected injector in response to the first total quantity and second total quantity of fuel.
In a third embodiment of the present invention, a system for trimming a fuel injector comprises a plurality of fuel injectors, an engine performance center adapted to measure an engine performance characteristic, and a controller adapted to receive a signal from the performance sensor, send multiple injection signals to the plurality of fuel injectors, determine the first fuel quantity injected by the plurality of injectors, suspend at least one of the multiple injection signals to partially suspend fuel delivery by one of a plurality of injectors, adjust the first fuel quantity to a second fuel quantity in order to maintain an engine performance characteristic at a relatively constant level, determine the second fuel quantity injected by the plurality of injectors, compare the first and second fuel quantities and determine a performance characteristic of the partially suspended injector.


REFERENCES:
patent: 4379332 (1983-04-01), Busser et al.
patent: RE33890 (1992-04-01), Ohnari et al.
patent: 5204816 (1993-04-01), Wright et al.
patent: 6112720 (2000-09-01), Matta
patent: 6189378 (2001-02-01), Kendrick et al.
patent: RE37807 (2002-07-01), Shinogle et al.
patent: 2002/0148441 (2002-10-01), Tuken

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