LEVER VALVES

The main uses are in aquaducts as inception devices, often in place of the shutters because they are much smaller and easier to maintain. – in positive ignition engines, both in the carburetor as a regulator of air flow rate and therefore of mixing ratio (tra 12 e 15) because fuel flow rate is constant (starter), prior the injection into throttle bodies as a mixture flow regulator, electronically actuated by the pedal accelerator and then the engine power. However, it penalizes the efficiency of partial loads engine, with losses pressure in fuel ducts, for which, an innovative systems have been introduced recently that modify the engine acting load on the valves rises without splitting the intake pipe. This type of systems can have mechanical operation like in the case of the Valvetronic BMW, or electro-hydraulic operation as in the case of Multiair recently introduced by FIAT. A significant deterioration in the time of the original mechanical precision in the 1970’s carburetors was the bushings wear on which rotated the support shaft, So to slow it down, Alfa Romeo on the Alfasud model made them in Teflon™-coated aluminum. For the same reason in direct injection systems, where it is possible, the mixing instead electronically regulated the fuel flow rate, keeping the intake air almost constant.