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Hub AI
Variable valve lift AI simulator
(@Variable valve lift_simulator)
Hub AI
Variable valve lift AI simulator
(@Variable valve lift_simulator)
Variable valve lift
Variable valve lift (VVL) is an automotive piston engine technology which varies the height a valve opens in order to improve performance, fuel economy or emissions. There are two main types of VVL: discrete, which employs fixed valve lift amounts, and continuous, which is able to vary the amount of lift. Continuous valve lift systems typically allow for the elimination of the throttle (which is otherwise normally a single valve constricting the entire engine’s intake airway).
When used in conjunction with variable valve timing (VVT), variable valve lift can potentially offer infinite control over the intake and exhaust valve timing.[citation needed]
In 1958 Porsche made application for a German patent, also applied for and published as British Patent GB861369 in 1959. The Porsche patent used an oscillating cam to increase the valve lift and duration. The desmodromic cam driven via a push/pull rod from an eccentric shaft or swashplate. It is unknown if any working prototype was ever made.
Fiat was the first auto manufacturer to patent a functional automotive variable valve timing system which included variable lift. Developed by Giovanni Torazza in the late 1960s, the system used hydraulic pressure to vary the fulcrum of the cam followers (US Patent 3,641,988). The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%.
In September 1975, General Motors (GM) patented a system intended to vary valve lift. GM was interested in throttling the intake valves in order to reduce emissions. This was done by minimizing the amount of lift at low load to keep the intake velocity higher, thereby atomizing the intake charge. GM encountered problems running at very low lift, and abandoned the project.[citation needed]
In 1989, Honda released their Variable Valve Timing and Lift Electronic Control (VTEC) system. Which switches to a separate cam profile at high engine speeds to improve peak power. Later versions added VVT as well as three stage valve lift.
Nissan introduced its Nissan Ecology Oriented Variable Valve Lift and Timing on its Nissan VVL engine it featured two-stage valve lift.
Toyota's first VVL system was VVTL-i, a two-stage valve lift system that also incorporates variable valve timing. Like VTEC it has a normal and "wild" profile on the same camshaft. This system was only used on the 2ZZ-GE engine.
Variable valve lift
Variable valve lift (VVL) is an automotive piston engine technology which varies the height a valve opens in order to improve performance, fuel economy or emissions. There are two main types of VVL: discrete, which employs fixed valve lift amounts, and continuous, which is able to vary the amount of lift. Continuous valve lift systems typically allow for the elimination of the throttle (which is otherwise normally a single valve constricting the entire engine’s intake airway).
When used in conjunction with variable valve timing (VVT), variable valve lift can potentially offer infinite control over the intake and exhaust valve timing.[citation needed]
In 1958 Porsche made application for a German patent, also applied for and published as British Patent GB861369 in 1959. The Porsche patent used an oscillating cam to increase the valve lift and duration. The desmodromic cam driven via a push/pull rod from an eccentric shaft or swashplate. It is unknown if any working prototype was ever made.
Fiat was the first auto manufacturer to patent a functional automotive variable valve timing system which included variable lift. Developed by Giovanni Torazza in the late 1960s, the system used hydraulic pressure to vary the fulcrum of the cam followers (US Patent 3,641,988). The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%.
In September 1975, General Motors (GM) patented a system intended to vary valve lift. GM was interested in throttling the intake valves in order to reduce emissions. This was done by minimizing the amount of lift at low load to keep the intake velocity higher, thereby atomizing the intake charge. GM encountered problems running at very low lift, and abandoned the project.[citation needed]
In 1989, Honda released their Variable Valve Timing and Lift Electronic Control (VTEC) system. Which switches to a separate cam profile at high engine speeds to improve peak power. Later versions added VVT as well as three stage valve lift.
Nissan introduced its Nissan Ecology Oriented Variable Valve Lift and Timing on its Nissan VVL engine it featured two-stage valve lift.
Toyota's first VVL system was VVTL-i, a two-stage valve lift system that also incorporates variable valve timing. Like VTEC it has a normal and "wild" profile on the same camshaft. This system was only used on the 2ZZ-GE engine.