Internal-combustion engines – Combustion chamber means combined with air-fuel mixture...
Patent
1996-04-11
1997-10-14
Wolfe, Willis R.
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
F02P 515
Patent
active
056761139
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling ignition angle/timing in combustion engines.
Combustion engines are desirably designed in order to extract maximum obtainable work for each mount of fuel supplied. In piston engines the start of combustion should take place at a point of time such that the combustion pressure is optimised with respect to amplitude and crankshaft position, obtaining maximum positive torque from the combustion engine. From U.S. Pat. No. 4,417,556 is previously known a method wherein the pressure peak position from the combustion is detected, using an ionisation sensor in the combustion chamber. The peak position of the ionisation current coincides with the position of the peak position of the combustion pressure. By controlling the crankshaft position of the combustion engine and detecting when the first order of derivative of the ion current changes sign, the pressure peak position determined, and if the determined pressure peak position deviates from a predetermined target value then the ignition timing is corrected. In U.S. Pat. No. 4,535,738 is shown a further developed solution of the method described in U.S. Pat. No. 4,417,556, using furthermore a weak diagnostic discharge at the ordinary spark plug before generation of the ordinary ignition discharge, which weaker diagnostic discharge is used to predict the propagation speed of the flame front and dependent on the predicted propagation speed make a correction of the ignition timing.
With the solutions mentioned in U.S. Pat. No. 4,535,738 and U.S. Pat. No. 4,417,556 difficulties arise when applied in mass produced engines and during the operating conditions these engines are subjected to a number of fuel varieties. The ion current signal, during real operating conditions especially at low load and idling, a very unstable signal having several local minimum and maximum values, thus changing the sign of the first order derivative several times. Large variations between successive combustion's, even in the same cylinder at constant load-speed and amount of fuel applied, and rough combustion's, leads peak position of the ion current being displaced as much as 10 crankshaft degrees from the peak position of the combustion pressure.
SUMMARY OF THE INVENTION
An object of the invention is, for a combustion engine having a measure gap arranged in the combustion chamber detecting ionisation current in the combustion chamber, which measure gap preferably consist of the spark plug gap of the combustion engine, utilising the ionisation current in the combustion chamber as a parameter representative of the cylinder pressure, and obtaining a more reliable ignition timing control dependent of the detected ionisation current Another object is to obtain a method for ignition timing control adapted for mass produced Otto engines, which engines cause comparatively large variations between successive combustion's, where the sign of the first order derivative of the ion current could change several times during the so called post ionisation phase due to unstable combustion.
Yet another object is to enable a feed back control of the ignition timing adapted for each individual engine and the conditions of the individual engine, obtaining optimum ignition timing.
The foregoing and other objects of the invention are achieved with the present invention by a method for controlling the ignition angle/timing IgnP in a combustion engine which includes detecting the degree of ionisation in at least one combustion chamber of the combustion engine by means of a measuring gap arranged in the combustion chamber having a bias voltage applied, thereby developing an ionisation current in the measuring gap having an amplitude dependent on the degree of ionisation. A function dependent on at least an ionisation current representative parameter is integrated over a predetermined range of crankshaft degrees. The actual value obtained from the integration is then compared with a target value to determine a value .DELTA.IgnP
REFERENCES:
patent: 4377140 (1983-03-01), Latsch
patent: 4417556 (1983-11-01), Latsch
patent: 4488528 (1984-12-01), Morikawa
patent: 4535738 (1985-08-01), Ma
patent: 4622638 (1986-11-01), Anderson et al.
patent: 4762106 (1988-08-01), Blauhut
patent: 5146893 (1992-09-01), Ohsawa
patent: 5189373 (1993-02-01), Murata et al.
patent: 5337716 (1994-08-01), Fukui et al.
patent: 5425339 (1995-06-01), Fukui
Johansson Hans
Nytomt Jan
Mecel AB
Wolfe Willis R.
LandOfFree
Method for ignition timing 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 ignition timing control in combustion engines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for ignition timing control in combustion engines will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1547995