The Function of The Ignition Coil in The Gasoline Sprayer Engine

In simple terms, its core function is to convert the low voltage (typically 6V or 12V) generated by the battery or magneto into a high voltage (tens of thousands of volts) sufficient to break down the spark plug electrode gap and produce a strong spark, thereby igniting the air-fuel mixture in the cylinder and enabling the engine to operate.

Let's break down its specific working process and functions:

1. Energy Conversion and Voltage Boost (Core Function)

· Low Voltage Input: The primary winding of the ignition coil receives low-voltage direct current from the engine's magneto (or battery), typically 6V or 12V.

· Electromagnetic Induction: When the engine needs to ignite (controlled by the ignition switch and points/breaker or an electronic ignition module), the current in the primary winding is suddenly interrupted. According to the principle of electromagnetic induction, this rapidly changing current generates a violently fluctuating magnetic field in the iron core of the ignition coil.

· High Voltage Output: This violently changing magnetic field cuts through the secondary winding (which has many more turns than the primary). Due to the transformer effect, an extremely high voltage is induced in the secondary winding, usually reaching 10,000 to over 30,000 volts.

Think of it as a "voltage booster."

2. Generating the Ignition Spark

· The generated high-voltage electricity is directed to the spark plug via the high-tension lead (spark plug wire).

· The high voltage causes an arc discharge across the small gap (typically 0.6-0.9mm) between the spark plug's center electrode and ground electrode—this is the electric spark we refer to.

· This spark has sufficient energy to reliably ignite the compressed gasoline-air mixture within the cylinder.

3. Key Role within the Engine System

· Ignition Timing: The operation of the ignition coil must be precisely synchronized with the piston's position. This is usually controlled by a magneto flywheel or triggering device linked to the crankshaft. High voltage is generated exactly when the piston is near Top Dead Center (TDC) on the compression stroke, ensuring correct ignition timing.

· Energy Storage and Release: In electronic ignition systems, the ignition coil stores electrical energy while the primary circuit is closed and releases it rapidly the moment the circuit opens, ensuring spark intensity and duration.

Differences from Traditional Automotive Ignition Coils

The ignition systems for small gasoline engines (typically single-cylinder two-stroke or four-stroke) commonly found on sprayers mainly come in two forms, both closely related to the coil:

1. Magneto Ignition System (More Common):

  · Has no external battery. The primary power for the ignition coil comes from a permanent magnet that rotates with the flywheel. As the flywheel spins, the magnetic lines of force cut through a charging coil (low-voltage coil), generating an induced current to supply the ignition coil's primary winding.

  · Triggering Method: The flywheel also has a lobe or a separate trigger coil used to control the "on" and "off" of the ignition coil's primary circuit at the precise moment, thereby generating the high-voltage spark.

  · Characteristics: Compact, self-sufficient, requires no battery, and works with a pull-start mechanism. This is the mainstream system for small garden machinery.

2. Battery Ignition System:

  · Similar to early automobiles, a battery (6V/12V) directly supplies stable low-voltage current to the ignition coil's primary winding.

  · The primary current is interrupted by contact points (breaker) or an electronic control unit to generate high voltage.

  · Characteristics: Requires a battery, and the battery must maintain sufficient charge.

Symptoms of Failure

If the ignition coil is faulty, the engine will typically exhibit the following symptoms:

· Complete Failure to Start: No spark is produced.

· Hard Starting: The spark is too weak for reliable ignition.

· Intermittent Stalling: Internal short circuits or poor thermal stability in the coil cause intermittent operation.

· Lack of Power: Insufficient ignition energy at high speeds.