Toyota has developed a new engine control system, called Valvematic, by combining its variable valve timing system, which continuously controls engine intake valve opening and closing times, with a new mechanism that controls the lift of the valves.
In an automobile engine, intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes determine valve timing, lift (or how much the valve is opened), and duration (or how long the valve is kept open). However such systems are fixed in functionality.
An engine with fully variable valve timing, lift and duration, on the other hand, isn’t, and would be more fuel efficient because the valves would always open at the right point, lift high enough and stay open for the optimal amount of time depending on the speed of the engine.
Hence, on a new 2.0-litre engine developed by Toyota that uses its new Valvematic system, fuel efficiency has been improved by 5% to 10% (depending on driving conditions) and CO2 emissions have been reduced.
Toyota plans to introduce the Valvematic system shortly, starting with a new vehicle model featuring the 2.0-litre engine.
Last September, Honda made a similar move when it announced that its new VTEC engine sported a VTEC (Variable Valve Timing and Lift Electronic Control) system that also combined continuously variable valve lift and timing control.