The CVT automatic gearbox evolves into the e-CVT: but what is it and how does it work?

A few days ago we discussed the automatic gearboxes most commonly found on the market today, which are the torque converter, the robotised dual-clutch and the continuously variable transmission (CVT). Today we are going to focus on the last one, the continuously variable transmission or CVT, an automatic gearbox that has equal numbers of fans and detractors, but which brands such as Toyota have managed to evolve so that people end up liking it.

Continuously variable transmission (CVT) gearboxes are used by numerous manufacturers, although Toyota is perhaps the brand most representative of this type of transmission, giving it more prominence and using it in models such as the Prius or the C-HR. But if we widen our view a little more, we will see that brands such as Subaru use it under the name Lineartronic, Mercedes-Benz has christened it Autotronic, and Audi calls it Multitronic. And if we move to the world of two wheels, we will see that it is the option used in scooters, since its small size and performance make it the ideal gearbox.

The continuously variable transmission was developed and evolved in the 1950s by the American of Dutch descent Huub van Doorne, introducing it to the market for the first time in the small DAF 600, thus becoming the first mass-production car to use it, and which DAF named the Variomatic transmission. It should be said, however, that as early as 1920, the English company Clyno Engineering Company introduced in its 10.8 model what would be the first version of a continuously variable transmission, also becoming the third largest manufacturer in the country behind Austin Motor Company and Morris Motors, companies merged years later.

The fact that this transmission is so widely used is due to its design and construction, since unlike most transmissions, where we have gears to create speeds, in CVT continuously variable transmissions we have pulleys, generally connected by belts or chains, which can vary their size to have a different transmission ratio, which is why, when we talk about CVT transmissions, you have probably seen it said that they have infinite gears.

In the evolution of CVT gearboxes appear the so-called e-CVT, in which the torque conversion function is carried out electrically through a small motor, so that the symbiosis between engine and gearbox is more finely tuned, thus achieving greater utilisation and optimisation of revolutions, engine torque and power, to which must be added the characteristics typical of a CVT continuously variable transmission: lower consumption and emissions and greater comfort of use for the driver.

Furthermore, with e-CVT transmissions the aim is also to eliminate the main problems or sensations that these gearboxes gave drivers, namely when pressing the accelerator we perceive a delay until the car starts to respond, or the fact that, also when accelerating, the engine revs too high, causing noise and not providing a sensation of power and acceleration.