Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
2002-08-02
2004-03-09
Kwon, John (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S1490FA
Reexamination Certificate
active
06701896
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
(Not Applicable)
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
(Not Applicable)
REFERENCE TO AN APPENDIX
(Not Applicable)
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an electrical ignition method for internal combustion engines using an arrangement of a plurality of coils and of a magnetic generator that rotates synchronously with the engine and whose magnetic field at the same time passes periodically through the coils and generates therein a sequence of magnetic flux changes per rotation. In this process, a sequence of corresponding alternating-voltage half-waves is induced in the coils. These are used:
to charge an energy-storage element, that is discharged by actuation of an ignition switch via the primary-coil winding of an ignition transformer to trigger an ignition spark, and
to form the voltage supply of a microelectronic and/or programmable control (for example, a microcontroller) that is used to actuate the ignition switch in an ignition time instant as a function of the alternating-voltage half-waves detected and/or of the state of the internal combustion engine, for example its rotational position or rotational speed.
Furthermore, the invention relates to an ignition module suitable for performing the generic ignition method that has a magnetizable yoke core surrounded by a plurality of induction coils. The latter is constructionally and geometrically formed with a first and a second limb. The first limb is surrounded by a charging coil, whereas the second limb is surrounded at least by the primary and secondary coils of an ignition transformer. The energy-storage element is connected to the charging coil. Furthermore, the invention relates to a computer-program product having program-coding elements that are provided to execute the programmable control in order to implement the said method.
2. Description of the Related Art
To achieve a prolonged burn-time and a high spark energy, it is known from U.S. Pat. No. 4,538,586 to trigger the ignition spark in an angular range in which a flux change is effected precisely in the core of the ignition transformer by the magnet wheel of the magnetic generator rotating past. This induces a voltage in the secondary coil of the ignition transformer that is used to prolong the burn-time and to enhance the energy of the ignition spark. As a result, the fuel mixture in the internal combustion engine ignites more reliably. Specifically, it is proposed to use only a subsidiary flux change to prolong the burn-time, namely to trigger the ignition process at the start of the last, second-greatest alternating-voltage half-wave, from the point of view of amplitude magnitude, of a half-wave sequence. This achieves in any case a reduced attenuation of the main-flux change, which is used for the charging phase preceding the ignition.
From DE 38 17 187 C2, it is known to derive voltage half-waves that do not correspond to a forward direction by means of a diode in an ignition circuit and thereby to contribute to an uninterrupted, attenuated oscillation in the primary winding of the ignition transformer and in the charging capacitor discharging via it. This is intended to ensure a long spark burn-time. The circuit, which does not have a microelectronic and/or programmable control, causes, in a comparable way to U.S. Pat. No. 4,538,586 or U.S. Pat. No. 5,513,619, only small current consumption from the charging coil in the angular range of the ignition.
U.S. Pat. No. 5,513,619 (see, in particular,
FIG. 6
b
therein) discloses an ignition module roughly of the type mentioned at the outset having a two-limb coil arrangement. The first limb in the rotational direction of the magnet wheel is surrounded by the ignition coil
124
and the subsequent, second limb is surrounded by a charging coil
126
. Again, the ignition time instant takes place precisely when a voltage is induced in the secondary coil of the ignition transformer by magnetic flux change, as a result of which the burning of the ignition spark is maintained for as long as possible. However, this ignition system does not provide a possibility of flexibly adjusting the ignition time instant by flexible adjustment to various magnet wheel/yoke-core limb geometries of diverse internal combustion engine types.
DE 197 36 032 A1 discloses an ignition method roughly of the type mentioned at the outset, in which only the first limb in the direction of rotation of a two-limb, roughly U-shaped yoke core serves to promote and intensify the magnetic flux in the coils used to charge and trigger and also in the ignition transformer. To increase the technical reliability and safety, it is proposed to reset (“RESET”) or initialize the programmable control (for example, single-chip microcomputer) at least once to its initial state within every engine rotation in order to eliminate any adverse interference effects present externally in a sustained manner. Furthermore, the problem of guaranteeing the burn-time of the ignition spark is mentioned for the case where the activation signal of the microcontroller or of the control stops at the ignition switch during the capacitor discharge, for example owing to an interference effect due to the ignition spark. For this purpose, it is proposed to design the discharge-current circuit in such a way that the discharge of the energy-storage element is started by a short pulse from the microcontroller and the discharge process is maintained by a differentiating element until discharge is adequate. However, in that case, a special complexity of the specific circuit configuration of the differentiating element has to be implemented so that a residual charge still remains in the energy-storage element after termination of the discharge process, as it were, as “free charge” for the next ignition spark triggering with then correspondingly prolonged ignition-spark time. Furthermore, it is again proposed to use only a subsidiary flux change to prolong burn-time, namely to trigger the ignition process at the start of the first alternating-voltage half-wave of a half-wave sequence. In any case, this makes possible a reliable orientation of the control in regard to angular position on the basis of the subsequent half-waves.
With regard to the further prior art, reference is made to U.S. Pat. Nos. 5,392,735, 4,924,831, 6,009,865, DE 40 17 478 and EP 0 394 656 B1.
In contrast, the object of the invention is to develop, avoiding the abovementioned disadvantages, a generic ignition method further in such a way that a prolonging of the ignition-spark burn-time (so-called top-up effect) can be achieved without additional circuit complexity with simultaneous optimization of the energy content of the ignition spark.
BRIEF SUMMARY OF THE INVENTION
To achieve this in an ignition method having the features mentioned at the outset, it is proposed, according to the invention, that within one rotation, there is chosen, for the triggering of the ignition spark to prolong its burn-time, such a time interval in which the primary and/or secondary coil winding of the ignition transformer is specifically influenced by one of the magnetic flux changes and the amount or range of the magnetic flux change used to prolong the burn-time is greatest within the respective sequence. This departs from the method prevailing in the prior art mentioned at the outset of using only the last magnetic flux change of a sequence for triggering the ignition and for supplying the ignition transformer with energy. Instead, the ignition time instant or the position of the ignition angle relative to the flux change is set in such a way that, in this rotation-angle range or angular interval, the strongest magnetic flux change (so-called main flux change), triggered by the magnetic generator magnet wheel rotating past, comes into effect in the secondary coil of the ignition transformer. In a continuation of the inventive idea, said magnetic flux change can then be available solely for prolonging burn-time because energy does n
Foster Frank H.
Kremblas, Foster Phillips & Pollick
Kwon John
Prufrex-Elektro-Apparatebau, Inh. Helga Müller, geb. Dutschke
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