Seminar on i-VTEC engine

ACHARYA INSTITUTE OF TECHNOLOGY MECHANICAL DEPARTMENT, BANGALORE

SUBMITTED BY , SUBHASH SHETTY USN: 1AY12ME123

INTRODUCTION i-VTEC is the acronym for intelligent VTEC (Variable Valve

Timing and Lift Electronic Control), an evolution of Honda's VTEC engine.

It made its debut in 2001. It is a system developed by Honda to improve the volumetric efficiency of a 4 –stroke internal combustion engine(i.e. improved economy).

The VTEC system uses two camshaft profiles and hydraulically selects between profiles.

It is distinctly different from standard VVT(variable Valve timing) which advances the valve timing only and does not change the camshaft profile or valve lift in any way.

What is i-Vtec system ?

The i-VTEC engine works by controlling the timing and lifting of the camshafts depending on engine speeds. The valves open a small amount during low engine speeds to achieve maximum fuel efficiency. The valves will open wider at higher engine speeds to achieve higher performance.

Honda i-VTEC is a system for fuel economy(intelligent-VTEC)

has VTC continuously variable timing of camshaft phasing on the intake camshaft of DOHC VTEC engines. The technology first appeared on Honda's K-series four-cylinder engine family in 2001 (2002 in the U.S.). In the United States, the technology debuted on the 2002 Honda CR-V.

Honda introduced many new innovations in i-VTEC, but the most significant one is the addition of a variable valve opening overlap mechanism to the VTEC system. Named VTC for Variable Timing Control

WORKING PRINCIPLE The cam controls the valve opening. At lower rpms the valves open to a

sufficient quantity to let enough air fuel mixture inside the engine. But at higher rpms the valves open and close in short duration thereby affecting the amount of air fuel mixture entering the engine.

VTEC allows an engine to alternate between two different camshaft profiles. In twin-cam configurations, each camshaft features three lobes per cylinder--its two primary lobes and its larger, longer-duration secondary lobe--which correspond to three respective rocker arms.

Under normal conditions, the centre rocker arm, which is paired to the

camshaft's larger, centre VTEC lobe, does little more than ride on what Honda calls its Lost Motion Assembly.

At a predetermined engine speed based upon the ECU, a 12V signal is sent to the engine's VTEC solenoid, which activates the process. Here, oil pressure forces a series of pins into place, engaging the centre rocker arm, which reacts against the camshafts' larger, centre lobes, forcing both valves to operate under the VTEC lobe's higher-lift, longer-duration profile.

Diagrammatic representation of VTEC SYSTEM

VTC (Variable Timing Control) Here, a specialized camshaft gear allows for continuously

variable intake camshaft phasing throughout the RPM range. Based upon all sorts of things ,like camshaft position, ignition timing, exhaust oxygen content and throttle position, a 50-degree range of camshaft phasing is possible (25-degree range on K24A2).

Much like VTEC, the camshaft gear is electronically controlled and hydraulically driven, resulting in reduced timing at idle and advanced timing at higher engine speeds, which increases valve overlap and power.

advantages Better fuel efficiency. High initial torque with relevant high power. Lower emission. Higher torque and stronger performance. Since VTEC creates more power without increasing displacement, the engine is likely to be smaller and lighter.

disadvantages Increase Engine complexity and cost. Decreased Engine life span. Not recommended for vehicles which

dose not need high torque. (vehicles which only used for slow transportation).

Higher wear and tear problems.

Scope for further development Use of different fuels for zero

emissions and better engine performance.

Lowering the cost. Use of better lubricating system on

cam lobes and VTC cam gears, wear and tear can be minimized.

conclusion With evolving modern technology in IC engines, i-

VTEC has made a good impression on long distance drivers and speed loving peoples.

Though being expensive than normal Engines, i-VTEC Technology gives us the best vehicle performance, better Fuel economy, emissions are reduced, derivability is enhanced and power is improved.

Undoubtedly Honda will continue to evolve their variable valve timing technology to new heights, meeting the needs of consumers and retaining its position as the premier developer of variable valve timing technology.

THANK YOU