Since the outset of the reciprocating piston engine era, engine designers have recognized the need for systems that provide infinitely variable valve (IVV) action including open/close timing, duration and lift. While a limited degree of IVV has been achieved with mechanical systems, the development of ideal infinitely variable systems has been difficult.
A promising IVV system, however, is being advancd at Valeo SA, a France based producer of automotive components and integrated systems. The Valeo IVV system referred to as â€œcamlessâ€ employs computer control of electromagnetically actuated engine valves replacing conventional cam actuation and phasers.. Energy consumption of the â€œcamlessâ€ system for a typical moderate size 4-cylinde car is said by Valeo to be under 250 watts at 3000 rpm.
Valeo reports that its â€œcamlessâ€ system applied to gasoline engines is cost competitive vs. diesels and that 20% reduction in both fuel use and emissions have been demonstrated When combined with other Valeo systems such as low consumption A/C compressor, beltless engine accessory drive, thermal management , dual clutch transmission and micro hybrid, 40% overall fuel economy gain is feasible according to the firm.
Valeo claims that 80% of the gain from its valve system can be obtained at reduced cost by application only to intake valves. . Its use on 3-cylinder engines could be very economic for small cars . For comparison, VW has begun marketing a 3-cylinder 1.4L diesel car with claimed 72 mpg fuel economy. A`gasoline version with â€œcamlessâ€ valves at equal thermal efficiency might be about 63.mpg; well below the EU target of 130 g/km CO2. While emotionally unsettling for many US car buyers , 3 cylinder cars driven by AI performed well and demonstrated good smoothness due to their balance shafts. For a given total displacement, 3 cylinders in place of 4 are inherently more efficient due to reduced thermal and friction losses. . .
AI recently sought an interview with Valeo valve system engineering personnel but was turned down by the firmâ€™s public relations representative who said customer relations at this time did not permit discussion that might indicate commercialization status. Valeo is a member of the Southwest Research Institite consortium development of the HEDGE system high efficiency dilute gasoline engine to which Ford has reportedly given high priority status. Ford CEO, Fred Mulally; credited with successful business turnaround performance at Boeing by adopting dynamic new aircraft technology and a high degree of outsourcing, is being closely monitored by auto industry analysts for bold moves. Fordâ€™s position on camless valve systems is not known. .
About the author: Bob Brooks is a member of the Society of Automotive Engineers and long time automotive technology journalist specializing in powertrains and fuels.