How does the variator?
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Sometimes, in automobile catalogs or in technical specifications, one can come across such a word as “variator”, which says little to many people. In fact, this invention belongs to the famous Leonardo da Vinci. A CVT is a type of transmission that appeared in the 50s of the last century. The principle of operation of the variator is significantly different from the usual work of the gearbox. It has no fixed gears, it smoothly changes the gear ratio during acceleration or slow motion of the car. There are several types of variators:
Consider how the variator works. For cars use V-belt and toroidal variators. Klinoremennye variators are most prevalent. Today, it is used by many car manufacturers and some of them have their own names, such as:
- Multidrive from Toyota;
- Multitronic from Audi;
- Multimatic from Honda et al
On the cars of the company Nissan install toroidal variators Extroid, which received great fame.CVT box, its principle of operation is to consistently change the diameters of the pulley, depending on the modes of operation of the engine. Since this is a continuously variable transmission, it allows the gear ratio to change very smoothly. Its advantage is the efficient use of power. This is due to the coordinated work of the crankshaft and the load on the car. Due to this, the torque changes continuously, there is no jerking, which ensures comfortable movement on the car. The variator box device includes:
- Management system;
- The mechanism by which the transmission of torque is provided;
- The mechanism that provides the reverse gear;
- Variable speed drive.
For transmission of torque, various types of clutch are used. High torque transmission torque provides a torque converter, thereby increasing the life of the gearbox.
Consider a V-belt variator, the principle of its operation. This type of variator consists of one or two belt transmissions. Transmission is carried out using two pulleys, which are interconnected by a V-belt.The pulley consists of two conical discs, they can move and move apart, resulting in a change in the diameter of the pulley. Their convergence occurs due to the use of centrifugal force, hydraulic pressure, spring force. In order to move the belt had the least resistance, tapered discs have a tilt angle of 20 degrees.
Belts for V-belt variators
It is clear that simple belts made of fabric or rubber will not fit here. With such belts, the car would not have traveled a thousand kilometers. For variators of this type, a belt made of steel tape or a set of steel cables is used, which has tapes of complex cross-section with steel plates strung on them. It is the edges of such plates that come into contact with the pulleys. This belt has the desired stiffness, which transmits the compressive force.
A metal chain is also used as a belt. It consists of plates that are connected by axes. Thanks to this design provides excellent flexibility. For its lubrication using a special liquid. The use of such a belt provides the lowest losses during the transmission of torque and higher efficiency.
In the variator box most often use an electronic control system, which should perform the following functions:
- Synchronous change of the diameter of the variator pulleys;
- Ensuring the work of the planetary gearbox, which is necessary for the implementation of the reverse movement.
The selector lever is used to directly control the variator. Depending on the selected control program, the gear ratio will change during acceleration. Unlike a conventional car, in which it is necessary to spin the engine on each gear, and then move on to the next gear, the car with the variator has the engine at the same speed and smoothly changes the gear ratio. At the same time, the acceleration rate is high and there is no need to waste time on gear changes. In addition, the variator is also "smart." If it happens to call, for example, on the hill, it will not leave the high gear engaged, the pulleys move back to increase the torque.
The disadvantages of variators include their expensive maintenance and expensive repairs. Replacing the belt may be needed after a run of 100-150 thousand. Km. Oil is more expensive for him than for a machine, but it’s necessary to buy it less often. Despite this, the popularity of their use is constantly growing.Now you know all about how the variator works.