CVT (Continuously Variable Transmission), direct translation is continuously variable transmission, i.e. CVT, we often say, by definition is not clear and specific gear, similar to the automatic transmission operation, but the speed ratio variation but it differs from the automatic transmission gear jump process, but continuously, so that continuous and smooth power transmission.
1.CVT the Glossary
CVT (Continuously Variable Transmission), direct translation is a continuously variable transmission, that is, we often say that the CVT, as the name suggests is no clear and specific range, similar to the operation of the automatic transmission, but it is different from the change in the speed ratio automatic transmission gear jump process, but continuously, so that continuous and smooth power transmission.
The main structure and working principle
2.CVT the
The system comprises a set of driving wheel, the driven wheel set, with a metal basic member and a hydraulic pump.
CVT works demonstration
the metal strip is made of metal rings and two beams hundreds of sheet metal. Driving wheel and the driven wheel set set by the movable and stationary discs, and the elements close to the cylinder side of the pulley the shaft can slide, the other side is fixed. The movable plate and the fixed plate are tapered structure, the tapered surface thereof to form a V-groove engaged with V-belt metal. Output power of the engine output shaft is transmitted to the first drive wheel of the CVT, and then transmitted through the V-belt to the driven wheels, the final reduction gear, a differential transmitted to the wheel to drive the car. Work driving wheel and the driven wheel disc movable axially movable to change the working radius of the driving wheel, the driven wheel tapered surface engaged with the V-belt, thus changing the transmission ratio through. Amount of axial movement of the movable plate is adjusted to achieve the driving wheel, the driven wheel cylinder pressure of the hydraulic pump by the control system as required by the driver. Since the radius of the driving wheel and the driven working wheel can be implemented continuously adjusted to achieve a continuously variable transmission.
In the hydraulic system of the metal belt type continuously variable transmission, the role of the slave cylinder is to control the tension of the metal strip, power from the engine to ensure efficient, reliable delivery. Active cylinder control bevel wheel axially movable position, with movement along the V-groove in the driving wheel set of metal, unchanged since the length of the metal strip, the driven wheel set along with the change of the metal V-groove in the opposite direction. Radius of gyration metal strip on the driving wheel set and a driven wheel set changes, continuous change in speed ratio.
When the automobile started, the working radius of the driving wheel is small, a large transmission gear ratio can be obtained, thereby ensuring a sufficient driving axle can beEnough torque to ensure a higher car acceleration. As vehicle speed increases, the working radius of the driving wheel is gradually increased, the working radius of the driven wheel is correspondingly reduced, the CVT transmission ratio decreased, so that the car can travel at a higher speed. Advantages and disadvantages of
3.CVT transmission
advantages
● because there is no general automatic transmission gear boxes, there will be no automatic gearbox shifting process, and the resulting sense of frustration shift disappeared, and therefore the power output of the CVT gearbox is linear, in actual driving very smooth.
● CVT transmission system can theoretically infinite number of gears, gear set freer than, ratio and performance, fuel consumption, exhaust emissions balance traditional gear drive system, are more easy to reach.
● CVT transmission mechanical efficiency, saving oil is much better than a normal automatic gearbox, second only to manual transmission gearbox, fuel economy than the much better. ?
shortcomings
Since there are so many advantages, why do not all cars are using CVT gearbox it has two factors:
● compared to traditional automatic gearbox is concerned, it costs slightly higher; and improper operation, then the higher the probability of the problem.
● CVT gearbox itself as well as its shortcomings, it is the limited transmission belt can withstand the strength of steel, in general, more than 1.8L displacement or 280N · M’sPower is its upper limit, but we also see that there are more and more models, such as Audi or Nissan, have to break this limit, I believe the problem will be solved gradually strip.