Diesel engines use internal combustion. In other words, fuel is introduced into a combustion chamber and then ignited. High compression heats the fuel to its ignition point, whereas a gasoline engine uses a spark plug to ignite a mixture of fuel and air.
Like a gasoline engine, a diesel engine uses a 4-stroke combustion cycle:
Diesel engines were once considered very inconvenient and primarily for agricultural purposes. Those days are long gone. The technology behind ignition systems and glow plugs has advanced significantly. Diesel engines are far cleaner, quieter, and more efficient nowadays.
Cold start – What does it mean?
The term “cold start” refers to when a diesel engine and its fluids are exposed to cold temperatures, e.g. below 5°C. The engine isn’t yet at its optimal temperature. Low temperatures make diesel engines harder to start. Therefore, glow plugs are crucial for every cold start. They warm up the engine combustion chamber to a sufficient temperature to create the ideal ignition conditions for the injected fuel. A glow plug not only provides the necessary energy for efficient combustion, but today’s low voltage systems also compensate for low or weak battery performance.
The main function of the glow plug is to provide an ignition aid at the start. However, stricter emission regulations brought new challenges to the automotive industry. Glow plug technology plays a key role here as well. The goal is no longer just to reduce the heat-up time of the engine, but also to improve fuel consumption, reduce soot, and lower emissions into the air we breathe.
The future of the diesel engine requires innovative and resource-efficient solutions. Dedicated Research & Development teams in HIDRIA are working closely with the leading OE global automotive manufacturers to meet the ever-demanding trends. With its innovative solutions and advanced technologies, HIDRIA is one of the leading suppliers of diesel cold start systems, especially glow plugs.
Modern glow plugs should meet the following requirements:
Bonus: Discover the latest generation of glow plugs – Glow plug with a pressure sensor.
The pre-heating system supplies the additional heat energy that is required for a clean and successful cold start.
Just before starting the engine, a voltage is applied to the terminal of the glow plug and the current flows through the heater and regulator coil. The glow plug is heated to its operating temperature and the heat energy is being transferred to the protective sheath causing it to glow.
Different engine designs require different times to reach a temperature suitable for stable combustion.
The glow plugs continue glowing after start-up to reduce the amount of white or blue smoke produced and maintain good idle stability until the engine is sufficiently warm. The post-heating phase depends on the engine temperature, driving mode, and other environment conditions.
|THREAD SIZE||RECOMMENDED TORQUE|
|GLOW PLUG||M8||8-14 Nm|
|CONNECTION NUT||M4||Max 2 Nm|
|M5||Max 4 Nm|
Table: Recommended installation torque specification