EnginePulley

AccelerateStop

CVT

DCTCruise

Bad.... Good!

Comparison of Engine Efficiency for CVT and DCT during AccelerationThe diagram above compares CVT and DCT for starting off, acceleration and cruising. The best fuel efficiency can be realized by continuously using the area where efficiency is good for the engine (the green area) from an early stage.

Transmission “Rivals” Learning From Each Other

CVT Evolution Part 2

Transmission helps improve fuel efficiencyIn the previous article in this series we looked at the three

types of automatic transmission systems and how among

them, CVT is unique. Let's quickly review: The three main

types of automatic transmission are conventional automatic

transmission (AT), dual clutch transmission (DCT), and

continuously variable transmission (CVT).

CVT and DCT appeared after regular AT and are now

included in the features of many automobiles, each working

towards improving daily fuel efficiency. Here it's important

that we learn about the relationship between car gasoline

mileage and transmission.

Transmission can improve car fuel efficiency in two ways.

One way is by raising the efficiency of transmission itself. As

transmission efficiency increases, it is possible to transfer it

to the tires without loss of engine power.

Another way is how transmission allows us to use the areas

of the engine that have good efficiency. What does this

mean? Well, different engines have revolution zones where it

can run with good fuel efficiency, and transmission targets

this ideal zone and thus mileage improves.

The results on the powertrain due to improved transfer

efficiency and engine efficiency greatly affect vehicle

mileage, and thus any transmission works to improve

efficiency. However, their main approaches are different. In

particular, let's look at how DCT and CVT contrast.

Dual clutch transmission, as the name suggests, has two

clutches, one for the odd-numbered gears (first, third, fifth)

and one for the even-numbered gears (second, fourth, sixth).

When you shift gears, the alternate gear is already selected,

and gear changing becomes faster. DCT’ s approach is to

raise transmission transfer efficiency in order to improve fuel

efficiency. It has the same kind of mechanisms as manual

transmission and, with its high transmission efficiency, in

particular it can extend mileage when cruising at high speeds.

CVT skillfully uses the engine's “best” partsOn the other hand, CVT raises fuel efficiency by using the

most efficient parts of the engine. As we saw before, CVT

can set the t ransmiss ion gear rat io f ree ly, and is

characterized by gear changing and driving that is seamless.

This transmission gear ratio can set the range of the ratio

widely and whether at low speed or high speed, it is able to

continue using the area that is best for mileage.

In other words, CVT tries to improve fuel efficiency by

maximizing the engine's potential. Compared to DCT, CVT is

able to use the efficient parts of the engine as soon as it

starts up.

CVT has also been evolving from year to year. The challenge

of upgrading transfer efficiency has now been achieved,

along with expanding the transfer gear ratio. It has become

possible to run on the engine's optimum rpm, with a much

wider range of speed than previously.

And not only the mechanics, the software that controls CVT

has also been evolving. Now it can interpret the driver's

commands through the operation of the accelerator and

steering for optimal shift control. On top of improving the

fuel efficiency, CVT’ s capabilities are advancing to allow you

to drive just as you want.

As we have seen, upgrading the performance of the

transmission is indispensable for improving car fuel

efficiency. And these three representative types of

transmission are set to keep on evolving even more in the

future.

New Generation XTRONIC CVTNissan's New Generation XTRONIC CVT features an expanded transmission gear ratio and improved transfer efficiency, in addition to an evolved adaptive shift control. This interprets the commands of the driver from the operation of the accelerator and the steer ing for opt imal sh i f t contro l . Coordinated control of the engine and transmission produces idea l fue l eff ic iency and dr iv ing performance.

Transmission is evolving