Automobile Electrical and Electronic Systems, 5th Edition

Ignition

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four-cylinder four-stroke engine with a compression ratio of 9 : 1, running at

speeds up to 5000 rpm. The following conditions are typical. At this speed the

four-stroke cycle will repeat every 24 ms.

• End of induction stroke –0.9 bar at 65°C.

• Ignition ring point –9 bar at 350°C.

• Highest value during power stroke –45 bar at 3000°C.

• Power stroke completed –4 bar at 1100°C.

Besides the above conditions, the spark plug must withstand severe vibration

and a harsh chemical environment. Finally, but perhaps most important, the

insulation properties must withstand voltage pressures up to 40 kV.

7.6.2 Construction

Figure 7.28 shows a ...