Saturday, August 21, 2010
Compression ratio of engine, whether it?
The term compression machine become one in the automotive lexicon. Some argue that it shows the ratio of air pressure proportional to gasoline / fuel. True?
Figure 1. Scheme 4 stroke engine
4 stroke engine has four action steps based on the Carnot cycle concept (Physical Science). That meet hukum2 thermodynamics. The four cycles are as follows:
1. Intake (step suction / suction stroke): exploitation of air and fuel mixture (can be derived from the carburetor or injection system)
2. Compression Stroke (step adder pressure): air and fuel mixture is compressed by the piston moving toward the top dead point (in the direction i in the figure). The best mixture according to (stochiometric) is 15:1, 15 parts of air volume and a volume of fuel (gasoline).
3. Combustion (step business / power stroke): here the mixture of fuel and compressed air that has been burned by using electric shock sparks from spark plugs. The result is a combustion and the volume of fluid / gas combustion products will expand abruptly (with a value of power) and will push the cylinder piston downward (toward the bottom dead point; in the direction G in the figure 1). And a few degrees before the piston reaches top dead point, the spark plug to ignite sparks splashed fuel - air, here the results of the combustion gas pressure will be increased by approximately 10x compared to the compression step.
4. Stroke Exhaust (Step disposal): here the rest of the combustion gases will be discharged out (to the exhaust) through the exhaust port (J).
These four processes can be described as follows:
Compression pressure is the average effective pressure that occurs in the combustion chamber just above the piston. Compression pressure was also divided by two definitions, compression pressure and compression pressure combustion motor.
Compression pressure is the pressure of this motor is often measured by the mechanical compression equipment to the units kPa gauge, psi or bar. Motor pressure finally better known as the compression pressure. This pressure reading compression pressure in the combustion chamber without ignition spark plugs, how to install compression gauge in spark plug hole and then pull the handle of the gas we fully (full open throttle) and then we crank the kick starter until the needle moves up and stops at a certain rate. Now this figure is the pressure of the compression motor.
This motor compression pressure range 900 kPa to 1400kPa for standard motors, or 9-13 psi.
The second is the pressure of the combustion chamber. This pressure is calculated when the engine starts or the combustion process occurs. This measurement does not use compression tool gauge anymore, but uses pressure sensors embedded in the cylinder head. Compression pressure combustion can achieve a 10x of motor pressure. This pressure in his end in a diagram describing the graph of P - theta (pressure versus crankshaft degrees).
In the second machine is not only there two steps:
1. step suction (intake) and combustion take place together, at the top and bottom of the piston.
2. step flue (exhaust) and compresi done bersama2.
The second process can be described as follows:
Well, so-called compression engines or, more precisely is the engine compression ratio combustion chamber volume ratio (when the piston is at the top of top dead point above) with a total space of piston cylinder (combustion chamber and the compression space). Suppose the volume of the combustion chamber and given the name Vb is the total cylinder volume Vt, and the volume of space compression is a compression ratio of VK it could be written as
Compression ratio: (Vt) / (Vb) = (Vb + VC) / (Vb)
Suppose X is the ratio of 9.0:1 Supra engine means the ratio Vt / Vb = 9. The higher the value of Vt / Vb then the energy can be produced engines will be even greater, because the compression air is getting better. Motorcycle engines now have a greater compression ratio. Eg Jupiter MX 10,9:1, Yamaha etc. Vixion 10:4:1. The higher the compression ratio engines need fuel with higher octane rating (the more resistant high pressure before burning). 9.0:1 compression ratio down enough given the premium (with a value of RON-Research Octan Number -> 88) while the rest require pertamax 92 and above.
Source: various sources, hkuracing