CAMLESS ENGINES-A NEW APPROACH IN I.C.ENGINES

CAMLESS ENGINES-A NEW APPROACH IN I.C.ENGINES

Abstract:

The internal combustion engine (ICE) finds its place in the market with latest design modifications in various components to improve efficiency, economy and overall performance. However, one component has remained unchanged in the internal combustion engine development i.e., the camshaft, has been the primary means of controlling the valve actuation and timing, and therefore, influencing the overall performance of the vehicle. Camless technology is capturing the future of internal combustion engines. It has been known to man that if valves could be controlled independently in an Internal Combustion Engine then there would be benefits like increased power, reduced emissions and increased fuel economy. In the camless technology valve motion is operated by valve actuators of electro-mechanical and electro-hydraulic type. In this paper we compare camless valve operation with conventional valve operation and we deal with the valve actuating mechanisms of camless engine by considering the electromechanical and electrohydraulic actuators as the important types of actuating valves in camless engines.

Keywords: Valve actuation, Electromechanical actuators, Electro-hydraulic actuators.

Introduction:

Cams, lifters, pushrods... all these things have up until now been associated with the internal combustion engine. But the end is near or these lovely shiny metal objects that comprise the valve train hardware in your pride and joy (Owners of the technically far more advanced rotary are excluded!) Camless engine technology is soon to be a reality for mass-produced vehicles. In the camless valvetrain, the valve motion is controlled directly by a valve actuator - there's no camshaft or connecting mechanisms. Various studies have shown that a camless valve train can eliminate many otherwise necessary engine design trade-offs.Automotive engines equipped with camless valvetrains of the electro-hydraulic and electro-mechanical type have been studied for over twenty years, but production vehicles with such engines are still not available. The issues that have had to be addressed in the actuator design include:

• reliable valve performance
• cost
• packaging
• power consumption
• noise and vibration

Noise has been identified as the main problem with the electromechanical actuator technology, arising from high contact velocities of the actuator's moving parts. For this noise to be reduced, a so-called soft-landing of the valves has to be achieved. In a conventional valvetrain, the soft-landing is mechanically embedded into the shape of the camshaft lobe.


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