Criteria S.I. Engine (Petrol or Spark Ignition Engine) C.I. Engine (Diesel or Compression Ignition Engine) Working Cycle Works on Otto Cycle or Constant Volume Cycle. Works on Diesel Cycle. Mixture During Suction Stroke Takes a mixture of air and petrol during the suction stroke. Takes only air during the suction stroke. Fuel Used Uses petrol as fuel. Uses diesel as fuel. Compression Ratio Has a compression ratio that varies from 6 to 10. Has a compression ratio that varies from 16 to 20. Engine Weight and Cost S.I. engines are lighter and cheaper. C.I. engines are heavier and costlier. Initial Cost Initial cost is lower compared to C.I. engines. Initial cost is high due to high compression ratio. Starting Starting is easy. Starting is difficult, especially in cold conditions. ...
CAMSHAFT - A cam is mounted on cam shaft which converts rotary motion camshaft into linear motion of follower.
WORKING OF CAMSHAFT - It is located in either the cylinder block or head.if the camshaft is located in the cylinder block and is placed above the crankshaft, the valve are to be opened through lifters, push rod and rockers arm
As cam rotate, it pushes up the lifter, which lift the push rod which moves one of the rocker arm up while other pushes the valve down to open it.
As the cam rotate, the valve springs forces the valve to close.
TYPES OF CAMSHAFT IN AUTOMOBILE ENGINE:-
1.) SINGLE OVERHEAD CAMSHAFT (SOHC) - These engines use one cam shaft for opening and closing of valve . they are known as SOHC.
It consists of timing gear, or sprocket and timing chain.
Sprocket is a like a gear , except that the teeth cut on its periphery.
The timing chain fit in the teeth of sprocket.
A timing chain and sprocket usually run when the cam shaft is driven by timing chain, the crankshaft and cam shaft rotate in the same- direction.
2.) DOUBLE OVERHEAD CAMSHAFT DOHC - in this one cam shaft operates the inlet valve and other camshaft operates the outlet valve.
In DOHC the crankshaft sprocket drives a timing chain which drives idler sprocket. The idler sprocket rotate the camshaft on each side.
TWIN CAM 16 VALVE TECHNOLOGY IN 4 CYLINDER ENGINE - Two Valve and 4 valve per Cylinder are mostly used.To improve breathing capacity and capacity to increase the power output many engines have 4 valve Cylinder.
The concept of DOHC lies in twin cylinder 16 valve technology. There are total 16 valve in 4 cylinder. That's means 4 valve in each cylinder. There are 2 inlet valve and 2 exhaust valve in each cylinder.
It means there are 8 inlet valve and 8 exhaust valves operates by two camshaft.