10-01-2011, 06:31 AM
ABSTRACT
The engines that are used now a days spot a constant compression ratio. It is economic for the compression ratio must decrease with the speed. But there is a practical difficulty for the engines to alter its compression ratio while in working. But there has been a break through, researchers have found out new ways by which the compression ratio can be altered. Thus comes a new breed of engines called the Variable Compression Ratio Engines. Volkswagen has come up with a production version too. In this type the head is held loose can change its gap with an increase in speed. Even though the engines spot a linear variation which is not desirable the engine delivers a comparatively lower consumption
[attachment=8088]
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eminarprojects
CHAPTER-1
INTRODUCTION
Variable compression ratio engines are those engines that have varied compression ratios at different engine speeds .used mostly in the diesel engine, these engines have high values of economy compared to the ordinary engines.
Compression ratio of an engine is the relative amount to which the volume available is compressed
It is given by the expression
This compression ratio that is available is to be high when the engine is working at low speeds.
When the speed is increased, the efficiency value is decreased .the requirement is a low compression ratio and that too by increasing the clearance volume.
Since the engine is running at low speeds at the first, the time availability is high, but when ever the speed increases the available time for combustion is less and hence the volume required is high.
The engines that are used now a days spot a constant compression ratio. It is economic for the compression ratio must decrease with the speed. But there is a practical difficulty for the engines to alter its compression ratio while in working. But there has been a break through, researchers have found out new ways by which the compression ratio can be altered. Thus comes a new breed of engines called the Variable Compression Ratio Engines. Volkswagen has come up with a production version too. In this type the head is held loose can change its gap with an increase in speed. Even though the engines spot a linear variation which is not desirable the engine delivers a comparatively lower consumption
[attachment=8088]
password
eminarprojectsCHAPTER-1
INTRODUCTION
Variable compression ratio engines are those engines that have varied compression ratios at different engine speeds .used mostly in the diesel engine, these engines have high values of economy compared to the ordinary engines.
Compression ratio of an engine is the relative amount to which the volume available is compressed
It is given by the expression
This compression ratio that is available is to be high when the engine is working at low speeds.
When the speed is increased, the efficiency value is decreased .the requirement is a low compression ratio and that too by increasing the clearance volume.
Since the engine is running at low speeds at the first, the time availability is high, but when ever the speed increases the available time for combustion is less and hence the volume required is high.
