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Power Electronics Applications in Vehicle and Passenger Safety
Published in Ali Emadi, Handbook of Automotive Power Electronics and Motor Drives, 2017
D.M.G. Preethichandra, Saman Kumara Halgamuge
Different automobile manufacturers use their own methods for obtaining the optimum condition by changing the valve timing. Honda introduced its Valve Timing Electronic Control (VTEC) in the late 1980s into its cars and soon followed by all the major manufacturers. This includes Toyota VVT-I and VVTL-I, Mitsubishi MIVEC, Nissan Neo VVL, BMW Double Vanos, Porsche Varicam Plus, and Rover VVC. The most sophisticated method among them at that time was Rover’s Variable Valve Control (VVC), introduced in 1995. This system has individual power electronic module to control each single valve in the engine. The advantage is these valves can be controlled very smoothly over the full-speed and -load range. This was then introduced to most of the high-end vehicles by the majority of car manufacturers.
The End of Compromise
Published in Patrick Hossay, Automotive Innovation, 2019
There are nearly as many ways to accomplish VVT as there are manufacturers. Honda was an early adopter of variable valve profiles with its VTEC engine. The engine switched between two cam profiles, allowing smooth operation and efficiency at low rpm, with greater performance possibilities when the engine switched to the more aggressive cam at 4,500 rpm. Honda’s recent engines include a three-stage VTEC with separate cams for low, medium, and high engine speeds. GM’s Intake Valve Lift Control uses an adjustable cam to shift the pivot point of the rocker arms and thus vary valve lift. FIAT’s MultiAir system utilizes an electrohydraulic system, using pressurized engine oil to actuate the intake valves, allowing for control of both lift and timing.
The reciprocating piston petrol engine
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
Another approach to variable valve timing is that pioneered by the Honda company, which is designated ‘VTEC’ for variable valve timing and lift electronic control system. Instead of allowing a controlled rotational movement for the camshaft relative to its driving sprocket, it utilizes three cam lobes and three rocker arms for each pair of valves in the four-valve combustion chambers (Figure1.124). The two outer cam lobes are active for the low and middle engine speed ranges, while the central cam with an increased lift profile becomes active for higher engine speeds to optimize breathing and power development.
Operational feasibility of a spark ignition engine which is subjected to VTEC management strategy
Published in Australian Journal of Mechanical Engineering, 2020
Lucky Anetor, Edward E. Osakue
In view of this, the variable valve lift and timing systems, such as Honda’s i-VTEC (intelligent-Variable Valve Timing and Valve Lift Electronic Control System), Porsche’s Vario-Cam and Audi Valvelift System (AVS), which employs multi cam mechanisms to adjust valve timing and lift are only able to achieve optimal adjustments of the valve timing and lift control over several engine speed or load ranges but are not able to achieve the best valve timing under all operating conditions. This is due to the fact that the valve advance angle, lag angle and duration angle of the engine’s intake and exhaust valves should increase as the engine speed increases, conversely, these quantities should decrease as the engine speed decreases, however, since the mechanics of variable valve timing system depends on the principle of camshaft phase modulation, it does not readily lend itself to these desired features under all engine operating conditions. It is worth mentioning that, research efforts concerning electronic cam-less valve engine operation are presently being undertaken with a view to developing mechanisms which produce valves that have flexible timings. Furthermore, either of the conditions (a) or (b) mentioned have some minor negative impact on engine performance and fuel economy.