Q3
With regards to modern 4-stroke diesel engine explain the following.
(16)
(a) The function of protection ring installed on the upper part of liner.
(b) The moderation in fuel injection drive system compared to conventional 4-stroke engine.
(c) Staggering of layout for multi hole nozzles.
(d) Effect of swirl and squish during the combustion process and how swirl and squish is generated
Reference Answer
### (a) The function of protection ring installed on the upper part of liner. A protection ring, also known as an anti-polishing ring or fire ring, is a critical component fitted at the top of the cylinder liner in modern 4-stroke diesel engines. **1. Primary Function: Prevention of Bore Polishing** * **Carbon Deposition**: During combustion, especially at low loads, hard carbon deposits can form on the top land of the piston (the area above the top compression ring).
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