Internal-combustion engines – High tension ignition system – Current or voltage sensing in coil primary
Reexamination Certificate
2000-06-23
2001-10-09
Solis, Erick R (Department: 3747)
Internal-combustion engines
High tension ignition system
Current or voltage sensing in coil primary
C123S609000, C123S650000
Reexamination Certificate
active
06298837
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an ignition system for internal combustion engines having a primary end short-circuit switch which short circuits the primary end of the ignition coil. So-called single spark coils (wherein each spark plug is allocated to an ignition coil) as well as double spark coils (in which two spark plugs are allocated an ignition coil) can be used. Other ignition systems are also conceivable which have a primary end short-circuit switch. In the following, only the single spark coil is considered because the method can be applied in the same manner to the double spark coils.
BACKGROUND OF THE INVENTION
The spark end is introduced in a controlled manner by the arrangement of a primary end short-circuit switch. In this way, the method is based on the ignition system having a shortened spark duration such as is known from DE 196 49 278. The method of the invention can also be applied to other ignition systems which shorten the ignition spark via a primary end short circuit with other means such as npn-transistors or thyristors.
An ion current measurement can be coupled with the ignition system as is known from DE 38 83 009 T2. The ion current measurement measures the ion current in the combustion chamber via the secondary end of the ignition coil and/or of the ignition transformer by means of the spark plug.
The operation of the switchoff of the ignition spark itself needs a certain time duration which can be disturbing under circumstances for the ion current measurement. Furthermore, the ignition coil and/or the ignition transformer and the short-circuit switch become unnecessarily warm because of the residual energy.
In view of this background, it is an object of the invention to:
minimize disturbances on the ion current measurement caused by the switchoff current;
to reduce the heat in the short-circuit switch and in the ignition transformer;
to keep the electrode wear low; and,
to ensure a reliable and rapid switchoff of the spark.
SUMMARY OF THE INVENTION
This object is solved with the features of the independent claims. Advantageous further embodiments of the invention are the subject matter of the dependent claims.
The invention must not perforce be connected to a detection of the ion current but offers many advantages in combination with a measurement of ion current.
A method which is good in series manufacture is introduced with the solution according to the invention of the above-mentioned problems. The method, inter alia, facilitates the realizability of the ion current measurement.
The solution according to the invention overcomes the above-mentioned disadvantages. A control variable is available for energy control via the closure time or the closure angle by the determination of a feature proportional to the residual energy.
According to the invention, a method for energy control on an ignition system for an internal combustion engine takes place with an ignition coil or an ignition transformer having a primary winding and a secondary winding and forming the ignition voltage. The primary winding of the ignition coil can be short circuited by means of a switch (called a short-circuit switch). An ion current can be measured with the secondary winding by means of one or several spark plugs. In the method, the primary current is detected in the short-circuit phase of the short-circuit switch with suitable means and transmitted to the control unit; the measurement quantity is processed in the form of a function or filtering in the control unit to a feature after actuation of the short-circuit switch; and, with the feature obtained, an energy control is built up over the closure time or closure angle.
The closure time or the closure angle is reduced in the event that the feature indicates a residual energy which is too great. The closure time or the closure angle is increased in the event that the feature indicates a residual energy which is too low.
In one embodiment, the maximum of the primary current directly after reaching the end of the spark is used as a feature, which is proportional to the residual energy, for controlling the energy via closure time or closure angle.
The drain source resistance of the short-circuit switch can be used as the means for measuring the primary current. The short-circuit switch can be configured as a field effect transistor.
Alternatively, the measurement of the primary current Is can take place via a resistance in the short-circuit loop.
In one embodiment, the control of the energy via closure time or closure angle can be suppressed in non-steady state operating points.
Furthermore, the control of the energy via the closure time or closure angle can take place in such a manner that the energy can be varied only in a specific time window or angle window which is delimited by a lower gate and an upper gate.
The limits of the closure time or of the closure angle can be controlled by a characteristic field. The characteristic field is dependent upon at least the load L and/or the rpm (n) and is stored, for example, in the control unit.
Furthermore, to control dynamic operations, the characteristic field can be subdivided into characteristic field regions. When leaving a characteristic field region, the actual closure time value or closure angle value is stored and, with a reentry into the characteristic field region, the values previously stored can be used as start values of the control.
REFERENCES:
patent: 5220821 (1993-06-01), Moser et al.
patent: 5321978 (1994-06-01), Brandt et al.
patent: 5571245 (1996-11-01), Ooyabu et al.
patent: 5801534 (1998-09-01), Hohner et al.
patent: 6047691 (2000-04-01), Ketterer
patent: 196 10 862 (1997-09-01), None
patent: 196 49 278 (1998-06-01), None
patent: 0 559 540 (1993-09-01), None
patent: 0 674 103 (1995-09-01), None
patent: 0 848 161 (1998-06-01), None
Foerster Juergen
Guenther Achim
Ketterer Markus
Wald Klaus-Juergen
Ottesen Walter
Robert & Bosch GmbH
Solis Erick R
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