12-05-2011, 04:48 PM
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Introduction:
The term six stroke engine describes two different approaches in the internal combustion engine developed since the 1990s to improve its energy and environmental efficiency
Some designs capture the waste heat from the four stroke Otto cycle or Diesel cycle and use it to power an additional power and exhaust stroke of the piston. Designs either use steam or air as the working fluid for the additional power stroke. As well as extracting power, the additional stroke cools the engine and removes the need for a cooling system making the engine lighter and giving 40% increased efficiency over the Otto Cycle or Diesel Cycle. The pistons in a six stroke engine go up and down six times for each injection of fuel.
These six stroke engines have 2 power strokes, one fuel, one steam or air.
Consider the following:
A 10% efficiency improvement in vehicle performance would save over $10 billion and reduce emissions of carbon dioxide by 140 million tons per year. A 20% efficiency improvement could reduce foreign oil used today by 1/3. Consumers would save billions of dollars in fuel cost. Reduction in emissions would be in the hundreds of millions of tons per year, and dependency on foreign oil would be drastically reduced.
Working of a basic DIESEL engine:
The cycle starts with the intake stroke, which begins when the piston is near top dead center. The intake valve is opened, creating a passage from the exterior of the engine (generally through an air filter assembly), through the intake port in the cylinder head and into the cylinder itself. As the piston moves toward bottom dead center, a partial vacuum develops, causing air to enter the cylinder. In the case of a turbocharged engine, the air is rammed into the cylinder at higher than atmospheric pressure. As the piston passes through bottom dead center, the intake valve closes, sealing the cylinder.
The compression stroke begins as the piston passes through bottom dead center and starts upward. Compression will continue until the piston approaches top dead center. The energy required for the compression stroke comes from the momentum of a flywheel on the crankshaft as well as (in multi-cylinder engines) other pistons in their power stroke.
The power stroke occurs as the piston reaches top dead center at the end of the compression stroke. At this time, fuel injection occurs, resulting in combustion and the production of useful work.
The final stroke is the exhaust stroke, which begins as the piston approaches bottom dead center following ignition. The exhaust valve in the cylinder head is opened and as the piston starts upward, the spent combustion gases are forced out of the cylinder. Near top dead center the intake valve will start to open before the exhaust valve is fully closed, a condition referred to as valve overlap. Overlap produces a flow of cooling intake air over the exhaust valve, prolonging its life. Following the completion of the exhaust stroke the cycle will begin anew
Study about the basic engine
Our AEROZETA is made out of a working four stroke diesel engine.
Features of our basic engine:
These are the features of the engine from which the AEROZETA has been built.
Displacement 1000cc
No. of cylinders 3
Type of fuel used Diesel
Type of ignition system compression ignition
Type of injection direct injection
Placement of camshaft overhead camshaft
Firing order 1-2-3
Drive of crank and cam Belt driven
No. of teeth on the crank gear 20
No. of teeth on the cam gear 40
Study about the CAMSHAFT of the basic engine:
Camshaft in an engine is essential to operate the valves of the engine. When the lobe of the cam hits the tappet of the valve, it is forced downwards through the valve guide present in the head of the engine.
The most important elements of the cam shaft are the timing gear and the construction and placement of lobes.
Construction of the timing gear:
The timing gear is made based on the requirement of the necessary gear ratio between the crank shaft and the cam shaft. For a typical four stroke engine the velocity ratio is 1:2 as the rotation of the cam shaft should be half the time of rotation of the crank shaft.
Study of Design of the cam profile of the basic 4 stroke engine:
According to the study made by our team members,
There is a raise of 10mm over 43º degrees of the cam rotation.
Dwell at the max height up to 3º- 4º degrees of the cam rotation.
There is a fall after the dwell up to the cam’s min radius, which ends when the cam completes 90º degrees of rotation.