International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 11 Issue: 07 | July 2024
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p-ISSN: 2395-0072
Method of achieving Variable Compression Ratio in Internal Combustion Engine Girish Tukaram Panchal1, Dr. Pravin T. Nitnaware2 1Research Scholar, D Y Patil College of Engineering, Akurdi, Pune 411044
Maharashtra, India
2HOD, Mechanical Engineering, Department of Mechanical Engineering
D Y Patil College of Engineering, Akurdi, Pune 411044 Maharashtra, India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Engines are widely used to convert chemical
improve performance and reduce emissions from engine. Compression ratio is one of the significant parameter which greatly influences the performance and emissions of Spark Ignition (SI) and Compression Ignition (CI) engines. Compression ratio describes the ratio of cylinder’s total volume when the piston is bottom-most position with the clearance volume when the piston is at top-most position. With the help of higher compression ratio in engine, it is possible to extract maximum energy from fuel during the combustion process and thermal efficiency can be improved. Fuel consumption can be reduced, and desired combustion temperatures can be achieved with the help of optimum compression ratio. Also expansion cycles can be extended, mechanical power output can be increased, and exhaust temperatures can be lowered by optimizing compression ratio.
energy into mechanical energy for power generation. They can be classified into Spark Ignition and Compression Ignition Engines based on the nature of combustion. In both engine types, air-fuel mixture is compressed before ignition, and the compression ratio determines the extent of compression. Higher compression ratios generally result in increased power output. While several parameters such as fuel-air ratio, valve timing, and spark timing can be controlled to enhance engine performance, there are limited options for dynamically adjusting the compression ratio during engine operation. This research aims to develop a method for modifying the compression ratio of an engine to achieve optimal performance.
Gasoline fuel is used in SI engine, and it is described with the parameters like Octane number, which is measurement of fuel’s resistance to detonation or preignition inside the engine.
The proposed approach involves connecting the piston to a primary connecting rod, which, in turn, connects to a first slider joint. The crankshaft is connected to a secondary connecting rod, which is linked to a second slider joint. Both slider joints can slide along a pivoted slider arm, enabling adjustment of the leverage around the pivot point.
1. INTRODUCTION
Higher-octane fuels exhibit greater resistance to autoignition under higher combustion pressure and heat. Similarly, the cetane number measures the combustion quality of diesel fuel or the ignition delay. Higher cetane numbers indicate shorter ignition delays and better fuel quality. Both gasoline and diesel fuels exhibit variations in performance and emissions depending on the compression ratio. However, the conventional construction of engines imposes limitations on achieving a variable compression ratio suitable for a variety of fuels. The fixed linkage of the connecting rod between the piston and crankshaft using rotary joints at both ends restricts the piston's travel to the rotation of the crankshaft, resulting in a constant compression ratio.
Engine converts various forms of energies into mechanical power and enables the mobility and transportation. Engines are categorized based on the parameters like type of combustion, fuels being used, etc. Achieving efficient and clean energy conversion has always been a challenge while improving the performance of engine. Multiple parameters like spark timing, air-fuel ratio, valve timing etc., are explored in the research work done by many researchers to
Overcoming the challenges posed by conventional engine construction, a few attempts have been made to achieve a variable compression ratio. These attempts include altering the piston stroke using hydraulic or electric actuators within the connecting rod, dynamically adjusting the piston-tocrankshaft distance, modifying the cylinder or piston height, among others. However, no attempts have been observed to achieve a constant clearance volume while varying the
By employing this variable compression ratio method, it becomes possible to achieve various performance and emission improvements in the engine. Additionally, a single engine can accommodate the combustion of different fuel types such as petrol, diesel, CNG, and hydrogen, among others. Key Words: Variable Compression Ratio, Constant Clearance Volume, Internal Combustion Engine, Linkage Mechanism, Kinematic Simulation.
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