Multiple Injections In Modern Diesel Engine

Modern diesel engine feels very smooth, responsive and less noisy. They have very less emission and more efficiency. The fact behind all these improvements in diesel engine is diesel multiple injection.

Multiple injection employs more than one injection in a single engine cycle (upto 5 injection in a single cycle). The 5 injection which occur in single engine cycle are:-

1. Pilot injection
2. Pre-injection
3. Main injection
4. After injection
5. Post injection

Pilot injection and Pre-injection- The small amount of fuel injected one or more times before the bulk fuel injection (main injection) is known as pre-injections. Injection far before the main injection is called pilot injection and the injection that occur just before the main injection is called as pre-injection.

ADVANTAGES of pre-injections

• It allows for good fuel-air mixture
• It shortens the delay in the main injection
• It drastically reducing NOx emission
• It reduces engine vibrations and other noise

After injection and Post injection- The small amount of fuel injected one or more times after the bulk fuel injection (main injection) is known as post-injections. Injection just after main injection is called as after injection and the injection that occurs far after the main injection is called as post injection

ADVANTAGES of post injection

• It allows for control of exhaust gas temperature
• It increasing after-treatment exhaust efficiency (catalytic converter efficiency)