| French-owned components
group Valeo has won OEM development contracts for camless engine technology
where the camshaft is replaced completely with electromagnetic actuators.
“By controlling residual gases and minimising pumping losses, the
technology cuts fuel consumption and emissions by 20 per cent,”
said Valeo. “Consumers also benefit from an increase in low-end
engine torque.”
The technology gives engine designers more freedom to play with intake
flow rates, valve and cylinder deactivation, the company says. Lower idling
speeds and faster warm-up times for catalysts are also possible.
“Production is scheduled to start in 2009 and will be in a gasoline
powertrain,” said Valeo. But introducing the technology will mean
changing the engine’s architecture and adding cost; its introduction
to the market is likely to be on low-volume engines.
Conventional piston engines use a camshaft to actuate the valvetrain.
The mechanics are relatively simple, but the force required to open the
valves is considerable. Sliding friction losses between the surface of
the cam and the cam follower are a drain on the engine’s efficiency,
particularly at idle.
Using a roller-follower valvetrain creates less friction and improves
efficiency, but completely removing the energy wasted in compressing the
valve spring has proved difficult. Bike firm Ducati uses a springless,
“desmodronic” system, but it is only really suited to high-revving
race engines.
Camless valvetrains actuated using either solenoids or magnetic systems
are more likely to suit passenger vehicles.
BMW is thought to have worked with Siemens VDO in the past on such systems,
but apparently without success. Eaton is industrialising a Lotus technology,
while AVL, FEV, Ricardo and Sturman Industries of the US also have research
projects.
Valeo’s technology is based on the principle of an oscillating mass-spring
system with two magnetic coils holding the valve alternatively open and
closed. The firm has two different systems, each comprising actuators,
a valve control unit, a wiring rail, and an ECU with appropriate strategies.
Valeo has demonstrated its “semi-camless” system, which manages
the inlet valves only. Its full system manages both the inlet and exhaust
valves.
Since acquiring Johnson Controls’ engine electronics division in
2005, engine management and power electronics have become core technologies
for Valeo.
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