18-06-2011, 03:07 PM
PRESENTED BY
VIJAY LAHRI
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OPPOSED PISTON ENGINE
HISTORY-
The first opposed-piston diesel engines were developed in the beginning of the 20th century. In 1907, Raymond Koreyvo, the engineer of Kolomna Works, built an opposed-piston two-stroke diesel with two crankshafts connected by gearing.
INTRODUCTION-
Following fig. shows systamatic working of a opposed piston engine..
OPPOSED PISTON ENGINE-
Opposed Piston Engine is a type of engine which has two pistons working in the same cylinder. Technically, opposed piston engine is just a variation in the design of conventional engine. Each of thecylinders of the engine has two pistons, one at each end. The main advantage of opposed piston arrangement over others is that they have a higher power to weight ratio.
CONSTRUCTION-
The cylinders of opposed piston engine are generally longer in size than those of the conventional engines. The arrangement of cranks is also such that both the pistons move towards and away from each other simultaneously. Moreover, the system works on a two stroke cycle and a uniform method of scavenging. In opposed piston engine the combustion chamber is the space left between the two pistons when both are at inner dead center postion.
It is this place between the pistons where the fuel injection valve, air starting valve, pressure relief valve and indicating cocks are fixed.
Most of the opposed piston engines have two crankshafts, one for the upper piston and other for the lower one. Both the crankshafts are arranged as trunk piston engines and through a series of connected gears.
MECHANISM OF OPPOSED PISTON ENGINE-
Here this opposed piston is used to drive a single wheel. With the help of opposed piston engine.`
PARTS OF OPPOSED PISTON ENGINE-
1-Intake for the fuel-air mixture. 2- Supercharger for forced induction of air and fuel. 3- Air box to buffer and distribute the mixture. 4-Waste valve to limit the pressure level. 5- Outlet crank mechanism (runs app. 20° past the outlet to achieve an asymmetric control diagram) 6- Inlet crank mechanism. 7- Cylinder with inlet and outlet slots. 8- Exhaust. 9- Water cooling jacket. 10- Sparkplug.
WORKING-
The air fuel mixture is pushed into the space in between the pistons. The ignition of the mixture pushes both the pistons downwards, leading to power stroke. The ignition is usually provided using a spark plug. As both the pistons move downwards, one of the pistons opens the outlet valve, which pushes the gas out of the exhaust, whereas the other piston opens the inlet valve, pushing in the fresh gas mixture. The compression stroke then takes place and the cycle repeats itself.
WORKING OF OPPOSED PISTON ENGINE-
EXAMPLE OF WORKING-
FUEL USED-
Opposed piston engine can be operated on both kind of fuel.
Gaseous.
Liquid.
Opposed piston operated mostly on liquid fuel because it provide more power to the engine.
Liquid fuel either be petrol or diesel.
EXAMPLE OF OPPOSED PISTON ENGINE-
Junkers Jumo 205 is used in airship mostly.
Commer TS3 "The Commer Knocker" commercial vehicle engine
Leyland L60 tank engine, used in the Chieftain tank; similar in layout to the Junkers Jumo 205 and Napier Culverin
Napier Deltic is used in marine and locomotive.
Rolls-Royce K60 engine, smaller and improved version.
ADVANTAGE-
The main advantage of opposed piston engine is that unlike conventional engines, where the stresses generated due to firing loads are transferred from the cylinders to the bedplates of the engine, no stresses are transferred and thus it have an excellent power to weight ratio. Moreover, the arrangement of opposed piston engines provides a higher degree of balance than the conventional engine.
CONCLUSION-
At last we can say that The novel configuration of this design eliminates the conventional cylinder head and valve train components offering an efficient, compact and simple core engine structure stroke per each crank revolution per cylinder.
In this engine highlights are..
Better power to weight ratio.
Low manufacturing cost.
Smaller volume for same power.
Low noise and vibration.
Fewer parts are count.
