Generac Power Systems 941-2 Section ENGINE IGNITION SYSTEM, Ignition Cage Assembly, Introduction

Section 6.4

ENGINE IGNITION SYSTEM

INTRODUCTION

The engine ignition system consists of the following major components:

•Ignition Cage Assembly.

•Ignition Sensor Assembly.

•Ignition Module (IM).

•Ignition Coil (IC).

•Spark Plug (SP1).

IGNITION CAGE ASSEMBLY

An IGNITION CAGE ASSEMBLY is factory installed onto the permanent magnet rotor hub. Two magnets are installed in the cage as shown in Figure 1 (50° apart), so that the north pole of one magnet faces away from the cage outer periphery and the north pole of the other magnet faces toward the cage outer periphery. A special fixture is used to install the cage onto the rotor hub so that the center line of the first magnet is 68° away from the Rotor Hub mounting hole as shown.

NOTE: Placement of the magnets on the Rotor Hub at the exact position stated above results in an ignition timing of 29 ° BTDC.

The Ignition Cage assembly cannot be replaced. The entire Rotor Hub must be replaced. Replacement Rotor Hubs will include a factory installed Ignition Cage assembly, and Magnetic Housing Assembly.

NOTE: Also refer to "Permanent Magnet Rotor" in Section 1.2 (Page 1.2-1).

Figure 1. Ignition Cage Assembly

IGNITION SENSOR

The Ignition Sensor is retained to the AC generator's Stator Adapter by means of two M4-0.70 x 8mm screws and lockwashers. The Sensor housing houses a circuit board. The entire housing cavity is filled with potting material.

As the generator's Permanent Magnet Rotor turns during operation, magnets on the Ignition Cage rotate past the Ignition Sensor to induce a timed low voltage pulse into the Sensor. This voltage pulse is delivered to an Ignition Module and serves as a timing pulse for the Module.

Figure 2. Ignition Sensor

See Figure 3. The Sensor circuit board mounts solid state components which are sensitive to magnetism. Magnets in the Ignition Cage rotate past the Sensor, causing the base of a transistor to be "pulsed". The transistor acts much like a "switch" or a set of "con- tact points". Pulsing the transistor base causes the "switch" to close and connect the "OUT" lead to the "GND" lead. This triggers the Ignition Module to deliv- er a primary ignition current to the Ignition Coil at timed intervals.

Figure 3. Ignition Sensor Schematic

IGNITION MODULE

While cranking and running, battery voltage is deliv- ered to the Ignition Module via Wire 14 from the A6060 circuit board. The Module will deliver this bat- tery voltage to the Ignition Coil based on the "timing" signal it receives from the Ignition Sensor.

The Ignition Module is retained in the generator con- trol panel by two capscrews.

Page 6.4-1