04-02-2013, 10:18 AM
A New Electro-Hydraulic Variable Valve-Train System for I.C Engine
1A New Electro-Hydraulic.pdf (Size: 2.39 MB / Downloads: 69)
Abstract
It has long been known that the internal
combustion (IC) engine can be significantly improved by
the use of variable valve timing (VVT) technologies, and
the engine designers have been investigating the potential
of variable valve train technologies leading to the
development of camless engines for many years. In recently
years, the variable valve technologies have a great
improvement and some valve-train systems have been used
to facilitate controlled auto ignition (CAI) combustion, a
new concept of internal combustion engine which is one of
the key research topics in the international arena.
INTRODUCTION
The worldwide trend towards more and more stringent
legislations on exhaust emissions is continuing and, more
attention is focus on our living environment at the same time.
The present discussion about possible limitation of CO2
emissions are putting farther pressure on the automotive
industry to improve the fuel consumption [1]. In response,
different technological solutions are available to realize the
improvement in fuel consumption, such as direct fuel injection
technology, engine downsizing and variable valve trains
technologies are currently considered the most promising ways
to achieve this goal. Further more, the new combustion
concepts under development is controlled auto ignition (CAI)
as well as named homogenous charge compress
ignition(HCCI)[2,3] burn combustion as well as combinations
of the above.
CONCUTIONS
Variable valve train system can offer the ability to achieve
flexible valve events to optimization engine performance with
different combustion mode for the potential of independent
program control of valve events, this means that innovative,
extendable solutions are being implemented for engine
management.
As the first step in this study, the valve action delay
characteristics of the electro-hydraulic variable valve system
were made clear. Attention was then focused on the valve
opening delay characteristics. Analyses and experiments were
conducted to investigate the statistical characteristics.
With the new electro-hydraulic variable valve system, CAI
combustion was realized by combustion chamber recirculation
and exhaust port recirculation as well as intake port
recirculation strategies. The BMEP reached 48% of SI
combustion mode, and have the potential to expend the
operating condition even more.