Internal-combustion engines – Spark ignition timing control – Electronic control
Patent
1997-08-26
1999-11-30
Wolfe, Willis R.
Internal-combustion engines
Spark ignition timing control
Electronic control
12340634, 12340638, 731173, F02P 5152
Patent
active
059923865
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for knock control in combustion.
Several knock detection methods for combustion engines are known.
Conventional methods use an accelerometer type of sensor, which sensor is mounted on the cylinder housing of the engine. By analyzing the frequency signal emitted from these sensors the typical frequencies for a knocking condition could be detected. When the intensity within the frequency range typical for a knocking conditions exceeds a certain level, then a knocking condition is established.
The disadvantage with this type of system is that other kind of vibrations, mechanical engine noise, road noise etc. , could have an impact upon the sensor output signal, and thus cause incorrect indications of a knocking condition.
In another method for knock detection a biased measuring gap is arranged within the combustion chamber. Ionization takes place within the combustion chamber during combustion, and the current developed in the measuring gap is representative for the combustion process. Similar to accelerometer type of sensors a knocking condition could be established by filtering out the superposed frequency in the ionization current typical for a knocking condition. This could be made using a system where the ordinary spark plug is used as the measuring gap, and where a substantially constant measuring voltage is applied in the grounded connection of the secondary winding of the ignition coil, as shown for example in EP,C,188.180 (=U.S. Pat. No. 4,648,367).
Knock detection using frequency analysis of the ionization current has the advantage that knock detection is not affected by mechanical engine noise, and if the ordinary spark plug is used as the measuring gap then no additional sensor on the engine is needed. Different detailed solutions for ionization current detected knock are further shown in: component a certain time after ignition spark generation is used in order to establish a knocking condition; optimum timing, until a knocking condition is detected via ionization current; and current is detected in the primary winding of the ignition coil.
In U.S. Pat. No. 5,220,821 a method is shown where any ion current detected knock is ignored if the ion current amplitude is too low or is fluctuating. This sorting out of incorrect indications of a knocking condition, if based upon frequency analysis of the ionization current, is insensible for incorrect indications of a knocking condition developed during operating conditions when the ionization current in its normal state is stable and exceeds an acceptable signal level. This method could mainly sort out incorrect indications for a knocking condition during specific operating conditions when the ionization current is low or fluctuating, for example at low rpms and low load, respectively at other unstable operating conditions at lean or by EGR diluted air fuel mixtures.
SUMMARY OF THE INVENTION
An object of the invention is for combustion engines, where a knocking condition is detected via frequency analysis of the ionization current developed within the combustion chamber, to be able to control a combustion in an optimal manner. Another object is that when a knocking condition is detected ideal operating parameters should be recaptured as soon as possible, following an initiated correction of these ideal operating parameters dependent of a detected knocking condition.
Another object is to be able to sort out incorrect indications of a knocking condition in a larger part of the operating range of the combustion engine, where a knocking condition is detected by using frequency analysis of the ionization current developed within the combustion chamber.
Yet another object is to be able to control the knock preventive control measure in a feed-back manner, such that a return back to ideal basic control data, i.e. ignition timing/fuel amount/charge air pressure, is obtained as soon as possible.
These and other objects are accomplished by a method which includes (a) obtaining an ionization s
REFERENCES:
patent: 4444172 (1984-04-01), Sellmaier et al.
patent: 4648367 (1987-03-01), Gillbrand et al.
patent: 5111790 (1992-05-01), Grandy
patent: 5220821 (1993-06-01), Moser et al.
patent: 5263452 (1993-11-01), Ohsawa et al.
patent: 5425339 (1995-06-01), Fukui
patent: 5743233 (1998-04-01), Unland et al.
patent: 5769049 (1998-06-01), Nytomt et al.
patent: 5803047 (1998-09-01), Rask
patent: 5861551 (1999-01-01), Morita et al.
Forsberg Peter
Nytomt Jan
Mecel AB
Vo Hieu T.
Wolfe Willis R.
LandOfFree
Method for knock control in combustion engines does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for knock control in combustion engines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for knock control in combustion engines will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1659756