Diesel Engine

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How a diesel engine works. Different working principles and process. Sample problems.

Transcript of Diesel Engine

  • Bedplatefoundation on which the engine is builtmust be rigid enough to support the rest of the engine and hold the crankshaft which sits on the bearing housing in alignment with transverse girdersat the same time, the bedplate has to be flexible enough to hog and sag with the foundation plate to which it is attached and which forms part of the ship structure

  • Bedplate

  • Frameload-carrying part of an engineit may include parts as the cylinder block,base, sump and end platesin two-stroke engines, frames are sometimes known as A-frames

  • Frame

  • Cylinder Block=engine blockpart of the engine frame that supports the engine cylinder liners, heads and crankshaftscylinder blocks for most large engines are made of castings and plates that are welded horizontally and vertically for strength and rigidity (stiffener)entablature = cylinder block which incorporates the scavenge air spaces in two-stroke engines

  • Cylinder block

  • Cylinder linera bore in which an engine piston moves back and forthreplaceablethe material of the liner must withstand extreme heat and pressure developed within the combustion space at the top of the cylinder, and at the same time must permit the piston and its sealing rings to move with a minimum of friction

  • Cylinder liner

  • Cylinder head= cylinder coverthe space at the combustion chamber top is formed and sealed by a cylinder headthe cylinder head of a four-stroke engine houses intake and exhaust valves, the fuel injection valve, air starting vale, safety valve(the two-stroke engine lacks the intake valve)

  • Cylinder head

  • Major running partspistonpiston rod crosshead connecting rod crankshaft & its bearings

  • Major running parts

  • PistonTransform energy of expanding gases to mechanical energy. It rides the cylinder linerone of the major moving partscrownskirtmust be designed to withstand extreme heat and combustion pressuremade of cast iron or aluminium (to reduce weight)

  • Piston

  • Piston ringApiston ringis a split ring that fits into a groove on the outer diameter of apistonin areciprocating enginesuch as aninternal combustion engineor steam engine.

  • Piston rodconnects the piston with the crosshead

  • Crossheadthe crosshead pin connects the piston rod to the connecting rodcrosshead slippers are mounted on either side of the crosshead pinthe slippers run up and down in the crosshead guides and prevent the connecting rod from moving sideways as the piston and rod reciprocate

  • Connecting rodit is fitted between the crosshead and the crankshaftit transmits the firing force, and together with the crankshaft converts the reciprocating motion to a rotary motion

  • Connecting rod

  • Crankshaft & its bearingsone of the largest moving partsit consists of a series of cranks formed in a shaftconverts reciprocating motion of the piston into rotary motioncounterweights for balancing purposes

  • Crankshaft

  • Bearings

  • Anti-dribble valveAnanti-dribble valveis a component of afuel injectionsystem used fordiesel engines. Its main function is to provide precise timing of fuel injection, particularly at the end of the injection time. If fuel was allowed to 'dribble' after the main phase of injection, this fuel would be too late for good combustion and so would be only partially burned as visible exhaust soot.

  • Check valve

  • Check ValveAcheck valveallows flow in only one direction and prevents back-flow. This maintains the injector pipe as full of fuel, as any leakage here would require the pipes to be primed again before the engine could be restarted.

  • Pop Valve

  • Pop valveA pop valve, like the later forms of steam locomotivesafety valve, only flows once a certain pressure has been reached. It then opens sharply, allowing full flow. This is used to make a sharp, abrupt start to fuel injection. This ensures that no fuel leaks into the cylinder until full combustion is imminent.

  • Unit injector

  • Unit injector(UI) is an integrated directfuel injectionsystem fordiesel engines, combining theinjectornozzleand theinjection pumpin a single component. Theplunger pumpused is usually driven by a sharedcamshaft. In a unit injector, the device is usually lubricated and cooled by the fuel itself.

  • electronically controlled unit injector

  • electronically controlled unit injectorAnelectronically controlled unit injector(EUI) is aunit injector(UI) with electronic control. The pressurized delivery of fuel iscamshaft-driven, but the timing of the injector's internal operations are controlled by theengine control unitso as to achieve certain advantages.

  • Injection Pump

  • AnInjection Pumpis the device that pumps fuel into the cylinders of adiesel engine.

  • It rotates at half crankshaft speed in a conventionalfour-stroke engine. Its timing is such that the fuel is injected only very slightly beforetop dead centreof that cylinder's compression stroke.

  • Jacketed fuel injection pipeThe pipe incorporates an outer jacket that shrouds the inner high pressure pipe. This jacket is usually metallic in construction and can either be a thin walled tube or convoluted hose.

  • Unit pumpThesystemis a modular high-pressuredieselinjection system. The systems use an individualinjection pumpmounted on the engine block for each cylinder.

  • The fuel pumps are driven by an extracamshaftlobe where each pump unit is connected to the injector via a short precise length high-pressure fuel line as opposed toUnit Injectorsystems which combines both a pump and an injector element in a compact unit.