Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1991-05-17
1993-05-11
Wolfe, Willis R.
Internal-combustion engines
Charge forming device
Fuel injection system
180197, F02P 5155, B60K 3100
Patent
active
052092038
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for controlling the torque of an internal combustion engine.
It is known that there can occur conditions which result in the engine speed of a vehicle oscillating which in turn causes an oscillation in the torque output from the engine. The torque oscillation can sometimes be audible or even result in a physical oscillation of the vehicle which is commonly called "kangarooing" in the United Kingdom. In some vehicles, torque oscillation of the engine occurs due to a mismatch of the resonant frequencies of the engine, transmission and final drive and this is inherent at certain vehicle and engine speeds. It has already been proposed to mitigate the effects of this torque oscillation by monitoring the rate of change of engine speed and to alter the ignition timing so as to alter the torque output of the engine. In other words, when a drop in engine speed is detected by the monitoring operation, engine torque is increased by advancing the ignition in order to counteract the drop. An increase in engine speed is likewise counteracted by retarding the ignition so as to damp out the oscillation.
This system is only possible because the resonant conditions are known and also the amount of phase shift between engine and wheel speed of the vehicle is a constant under these conditions. The requisite ignition timing variation can therefore be evaluated.
There exists another set of conditions which may induce "kangarooing" and that is during acceleration. Here, the phase shift between engine and wheel speed is not constant and so the technique proposed above cannot be used.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and an apparatus for controlling the torque of an engine which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method of controlling the torque of an internal combustion engine of a vehicle, including the steps of deriving a signal indicative of the speed of the engine and varying the ignition angle in a direction to counteract variations in engine torque, wherein a further signal is derived indicative of the wheel speed of the vehicle, differences between the signals indicative of engine speed and wheel speed are detected, and the ignition angle is varied in response to the detected difference.
In accordance with another feature of the present invention, the difference signal can be integrated, and the integrated signal is used as input to a load/speed dependent engine ignition map.
Still another feature of the present invention is that the integration can be established by means of a feed back loop.
In accordance with a further feature of the present invention an apparatus is proposed which has means for deriving a signal indicative of the speed of the engine, means for deriving a further signal indicative of the wheel speed of the vehicle, means for subtracting the signals to produce a resultant signal, an integrator for integrating the resultant signal, and means for deriving ignition angle correction signals and including a feed back loop.
The integrator can have a time constant which is a function of the elasticity of transmission.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a basic block diagram representing a vehicle expressed as spring mass system;
FIG. 2 is a block diagram similar to that shown in FIG. 1 but useful in explaining the effect of the present invention; and
FIG. 3 is an oscillograph showing the effec
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Kaltenbrunn Peter
Ott Karl
Schray Bernhard
Wild Ernst
Robert & Bosch GmbH
Striker Michael J.
Wolfe Willis R.
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