The MAHLE EvoTherm valve is the latest low-cost solution based on a conventional hollow valve. MAHLE has developed a new technology based on a conventional hollow valve with cylindrical bore, whereby an extended hollow cavity can be made in the valve head with just one additional process: electrochemical machining (ECM). This enlarged hollow space allows liquid sodium to dissipate the heat during engine operation even better. The valve head is cooled by the shaker effect: the hollow space is not completely filled with sodium, so that it is shaken as the valve moves; the sodium breaks down and thereby produces significantly greater heat dissipation via the valve guide.
This technology can be used for both intake and exhaust valves to achieve a reduction in fuel consumption. The valve mass is likewise reduced by 3% to 6% compared with conventional hollow valves. An internal high-stress endurance test to establish service life has also been concluded positively. The EvoTherm valve is an important addition to the MAHLE product portfolio.