Internal-combustion engines – Combustion chamber means having fuel injection only – Using multiple injectors or injections
Reexamination Certificate
1999-05-14
2001-02-27
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Using multiple injectors or injections
Reexamination Certificate
active
06192855
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method for use in controlling the operation of the fuel system of a compression ignition internal combustion engine. The invention is particularly applicable to controlling the quantity of fuel supplied during a pilot injection which, in use, is followed by a main injection.
It has been found that the levels of combustion noise and emissions produced by a diesel engine can be reduced by supplying each cylinder with a small pilot injection prior to supplying a main injection to the cylinder. It is desirable to be able to monitor the operation of an injector in order to accurately control the quantity of fuel supplied in the pilot injection.
GB 2305727 describes a method for determining the minimum drive pulse length which must be applied to an injector to cause delivery of fuel, the method involving filtering the output of an engine mounted sound sensor to provide a signal indicative of movement of a valve needle of the injector.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of controlling the operation of a fuel injector of a fuel system using a control system of the type comprising an accelerometer associated with an engine and arranged to sense vibrations thereof, and monitor means arranged to monitor the output signal of the accelerometer to detect vibrations of the engine, the method comprising applying a drive pulse to the injector to cause delivery of a pilot injection of fuel, using the monitor means and the accelerometer to determine whether or not the application of the drive pulse results in combustion in the cylinder of the engine associated with the injector, and modifying the duration of the drive pulse to determine the minimum pulse length which must be applied to the injector to cause combustion.
Combustion is conveniently sensed by filtering the output of the accelerometer using a band pass filter which passes vibrations caused by combustion and noise at a frequency falling, for example, within the range 6-8 kHz, and comparing the filtered signal with a similarly filtered signal derived from a point in the operating cycle of the engine where it is known that combustion is not occurring in order to compensate for background noise.
The minimum drive pulse length which results in combustion of fuel can be used in subsequent control of that injector to accurately control the quantity of fuel supplied by the injector both during pilot injections and during subsequent main injections, in use.
The method further permits the quantity of fuel delivered during the pilot injection to be monitored. If the ratio of the filtered signal indicative of the level of combustion and noise to that of noise alone becomes too high, then this indicates that the quantity of fuel delivered is too high, and the drive pulse length is reduced. If the ratio remains too high, an indication may be produced that a fault has occurred in the operation of the injector.
REFERENCES:
patent: 5005549 (1991-04-01), Pernpeintner et al.
patent: 5408863 (1995-04-01), Sawyers et al.
patent: 5482016 (1996-01-01), Ohishi et al.
patent: 196 12 179 (1997-08-01), None
patent: 2 277 173 (1994-10-01), None
patent: 2 305 727 (1997-04-01), None
patent: 7-12002 (1995-01-01), None
patent: 9-144583 (1997-06-01), None
Patent Abstracts of Japan, vol. 012, No. 404 (M-757), Oct. 26, 1988 & JP 63 147956 A (Nippon Denso Co. Ltd.; others: 01), Jun. 20, 1988.
Andrus Sceales, Starke & Sawall
Dolinar Andrew M.
Lucas Industries PLC
LandOfFree
Control method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2579387