Patent ID: 9702332
Date: 2017-07-11
CPC Classifications: F02P

Claim:
1. An ignition device, comprising: a spark plug that is attached to a cylinder head of an internal combustion engine such that a center electrode and a ground electrode project into a combustion chamber of the internal combustion engine; and an ignition coil having a primary coil and a secondary coil that are magnetically coupled with each other, the center electrode and the ground electrode opposing each other in an axial direction of the spark plug, a gap being formed between the center electrode and the ground electrode such that a discharge spark is generated in the gap, energization of the primary coil being started and subsequently interrupted to apply a high voltage to the center electrode such that the discharge spark is generated in the gap, wherein: the internal combustion engine is configured to generate airflow in a predetermined direction to the spark plug during a compression step; a voltage restricting means is included that restricts an output voltage of the secondary coil after the energization of the primary coil is interrupted to a predetermined voltage or less; the ground electrode has a leg portion that extends from a housing of the spark plug and an opposing portion that extends in a direction intersecting with the leg portion and forms the gap by opposing the center electrode, the ground electrode having a width of between 2.0 mm and 2.6 mm; the leg portion is attached to a position further upstream than the gap in a flow direction of the airflow during the compression step; and the spark plug is attached to the cylinder head such that an angle is between 10 degrees and 30 degrees, where the angle is an angle between a flow direction of the airflow of air-fuel mixture during the compression step and a line that connects a center of the leg portion and a center of the center electrode which are viewed from a tip side in an axial direction of the spark plug.