Question
Download Solution PDFFor the compression stroke of a two-stroke diesel engine which of the below statements is correct?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
Two-stroke Petrol engine:
- To produce power in a two-stroke engine the following operation takes place in the sequence given.
- One working stroke for each revolution of the crankshaft is called two strokes, i.e. from TDC to BDC and then BDC to TDC.
- A two-stroke engine does not require valves because in the two-stroke engine there are ports (transfer port and exhaust port) present in the engine cylinder which are covered and uncovered by piston reciprocation motion and charge transfer takes place.
Working of Two-Stroke Engine:
First Stroke (Suction and compression):
- As the piston moves up from BDC towards TDC, it closes the inlet port, exhaust port, and transfer port.
- Further upward movement of the piston results in compressing the mixture in the cylinder and opening of the inlet port.
- The upward motion of the piston creates a partial vacuum inside the crankcase below the piston, and the air/fuel mixture is drawn into the crank-case through the inlet port.
- The exhaust and transfer port remain closed during the operation of the upward stroke and the charge which reached above the piston during the previous stroke is compressed.
- For the compression stroke of a two-stroke diesel engine, first transfer port closes then the exhaust port closes so option 3 is correct.
- Thus, suction and compression stroke takes place during the piston moves from BDC to TDC.
Second Stroke (power and exhaust):
- The piston is forced downward from the TDC. During this stroke, the exhaust port opens and burnt gases escape into the atmosphere.
- Further downward movement of the piston opens the transfer port and allows the partially compressed mixture, received during the previous stroke, to reach the combustion chamber from the crankcase.
- The piston head has a spherical shape. It deflects a fresh charge of fuel mixture up into the cylinder.
- The mixture flows down and pushes the burnt gases out, through the exhaust port. This process is called scavenging.
Last updated on Jul 1, 2025
-> SSC JE ME Notification 2025 has been released on June 30.
-> The SSC JE Mechanical engineering application form are activated from June 30 to July 21.
-> SSC JE 2025 CBT 1 exam for Mechanical Engineering will be conducted from October 2 to 31.
-> SSC JE exam to recruit Junior Engineers in different disciplines under various departments of the Central Government.
-> The selection process of the candidates for the SSC Junior Engineer post consists of Paper I, Paper II, Document Verification, and Medical Examination.
-> Candidates who will get selected will get a salary range between Rs. 35,400/- to Rs. 1,12,400/-.
-> Candidates must refer to the SSC JE Previous Year Papers and SSC JE Civil Mock Test, SSC JE Electrical Mock Test, and SSC JE Mechanical Mock Test to understand the type of questions coming in the examination.