Inductive Ignition Systems Explained: Ignition Coil & Driver Stage Function
Reference · 1992-1995 TaurusAll 37 manual pages
Manual page describing inductive ignition systems and ignition coils, with a small schematic figure of ignition coil distributions.
Part of 1992-1995 Ford Taurus Manual Pages
This scanned page comes from an automotive engineering reference (Bosch-style technical manual) covering spark-ignition engine ignition systems. It concludes a discussion of how mixture dilution and ignition timing affect NOx emissions, noting that with a stoichiometric (λ = 1) mixture required for 3-way catalytic converter operation, adjusting ignition advance is the only remaining option for optimizing emissions. The main section introduces inductive (coil) ignition systems, explaining that the coil stores ignition energy and generates the high voltage needed to create an arc at the spark plug, contrasting this with capacitor-discharge ignition (CDI). The Ignition Coil section describes its function and design: two magnetically coupled copper windings (primary and secondary) transform current and voltage per the turns ratio, with modern coils using a laminated iron core, bobbin-wound primary, disc- or chamber-wound secondary, and epoxy-resin encapsulation for insulation. The Ignition Driver Stage section explains that multi-stage power transistors switch primary current (replacing contact-breaker points) and limit primary current and voltage. Figure 1 shows schematic diagrams of three ignition coil types: a single-spark coil for rotating distribution, and single-spark and dual-spark coils for static distribution, with terminal designations (15, 1, 4, 4a, 4b). The page is generic technical reference material, not vehicle-specific.
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Frequently asked questions
- How does an inductive ignition coil work?
- The coil consists of two magnetically coupled copper windings (primary and secondary). Energy stored in the primary winding's magnetic field is transmitted to the secondary side, and current and voltage are transformed according to the turns ratio of the two windings.
- What does the ignition driver stage do?
- Ignition driver stages use multi-stage power transistors to switch the flow of primary current through the coil, replacing the contact-breaker points used in earlier systems. The driver stage also limits primary current and primary voltage to prevent excessively steep increases of secondary voltage.
- How are modern ignition coils constructed?
- Modern coils feature an iron core made of individual metal plates inside a synthetic casing. The primary winding is wound around a bobbin mounted directly on the core, concentrically enclosed by the secondary winding (a disc or chamber winding for improved insulation resistance). All elements are enclosed in epoxy resin for insulation.
- What is the alternative to storing ignition energy in a coil?
- Ignition energy can alternatively be stored in a condenser, in what is called high-voltage capacitor-discharge ignition (CDI).
- What coil types are shown in Fig. 1?
- Fig. 1 shows three schematic ignition coil configurations: (a) a single-spark coil for rotating distribution, (b) a single-spark coil for static distribution, and (c) a dual-spark coil for static distribution.
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