How does a variable valve work?
A simple valve and engine cross-section. Variable valve timing enables these different behaviours by changing how the intake and exhaust valves work at different engine speeds. Thus, it helps optimise the engine’s performance, whilst also improving fuel economy and emissions.
What is VVT and how does it work?
In internal combustion engines, variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. Two-stroke engines use a power valve system to get similar results to VVT.
Who invented VVT?
Corliss Orville Burandt
Variable valve timing/Inventors
What are the advantages of variable valve timing?
VVT controls the flow of air and exhaust Engine valves control the intake of fresh air and fuel, and the exhaust of combustion gases. VVT and lift systems adjust the timing of the valves to match the operating conditions of the engine. This improves efficiency over a wide range of engine operating speeds.
How does variable valve timing work?
Basically, it varies the valve timing by shifting the phase angle of camshafts. For example, at high speed, the inlet camshaft will be rotated in advance by 30° so to enable earlier intake. This movement is controlled by engine management system according to need, and actuated by hydraulic valve gears.
Which engines have VVT?
Following is a list of terms used by each automaker to denote an engine with VVT technology:
- Alfa Romeo – Twinspark technology.
- Audi – VVT.
- BMW – Valvetronic, VANOS and Double VANOS.
- Ford – Variable Cam Timing.
- GM – Double Continuous Variable Cam Phasing (DCVCP), Alloytec and Variable Valve Timing (VVT)
Who uses VVT?
Toyota announced VVT-i in 1995, and it was introduced in the U.S. on the redesigned 1998 Lexus LS 400. The model-year 2000 Celica was the first Toyota model in the U.S. with it. All current Toyota models in the U.S. use VVT-i engines except the Mirai fuel-cell vehicle, the 86 coupe and Supra sports car.
What are the advantages of Variable Valve Timing?
What are the benefits of variable valve train technology?
4 Advantages of Variable Valve Timing (VVT) Engines
- Higher RPM.
- Better Fuel Economy.
- Lower Carbon Emissions.
- Increased Engine Lifespan.
How is the timing of the valvetrain controlled?
Valvetrain. Valvetrain opening/closing and duration, as well as the geometry of the valvetrain, controls the amount of air and fuel entering the combustion chamber at any given point in time. Timing for open/close/duration is controlled by the camshaft that is synchronized to the crankshaft by a chain, belt, or gear.
Who is the inventor of variable valve timing?
It was invented by Honda engineer Ikuo Kajitani. It is distinctly different from standard VVT (variable valve timing) systems which change only the valve timings and do not change the camshaft profile or valve lift in any way.
What makes up the valvetrain of an OHV engine?
A typical ohv valvetrain consists of valves, rocker arms, pushrods, lifters, and camshaft(s). Valvetrain opening/closing and duration, as well as the geometry of the valvetrain, controls the amount of air and fuel entering the combustion chamber at any given point in time. Timing for open/close/duration is controlled by…
Where did the idea of variable valve opening come from?
The history of the search for a method of variable valve opening duration goes back to the age of steam engines when the valve opening duration was referred to as “steam cut-off ”.