Sectional drawing of the FlexWork valve drive. (Image Courtesy of Empa.)
As most gearheads are aware, the valve train acts as the lungs of an engine, managing the intake of air for combustion and the discharge of post-combustion exhaust. Modern engines control these inputs and outputs through complex mechanical means, but traditional mechanical control has its drawbacks. First, valve trains are complex and therefor expensive to design and manufacture. Second, once a valve train is built, its mechanical control methods can’t be modified to meet new operating conditions.
Empa’s latest invention intends to change that.
In their latest foray into engine technology, engineers have built a hydraulically actuated system that is controlled electronically by a solenoid coil.
“As soon as a control current flows, a specially designed hydraulic valve opens, allowing hydraulic fluid to open the gas exchange valve to the desired extent in milliseconds counter to a spring. When the current is switched off, the gas exchange valve is closed again by the spring force and feeds a large part of the hydraulic energy required for opening back into the hydraulic system. The system achieves a significantly lower energy requirement over a wide operating range compared to camshaft-driven systems. Together with an optimized gas exchange, the fuel consumption of the test spark-ignition engine is about 20 percent lower than with conventional valve control using a throttle in combination with camshafts in the low load range typical for passenger cars.”
According to Empa, after performing several months on a test bench, the new valve train model has improved test-spark fuel consumption by 20 percent when compared to traditional valve controls that employ a mechanical control method.