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XTRONIC CVT

CAR TECHNOLOGY

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CVT for 3.5-liter class engine
CVT reduces emissions, provides "driving pleasure"

CVT (Continuously Variable Transmission) is a system with seamless, “stepless” gear transmission. Early on Nissan understood the merits of CVT, low-fuel consumption and seamless acceleration, developing and adopting the technology for its vehicles.

Extending the attributes of the efficient CVT even further, XTRONIC CVT now offers powerful acceleration performance that is also a pleasure to drive.

Technology Functionality
CVT is a “stepless” transmission system. As opposed to MT (Manual Transmission) or AT (Automatic Transmission), CVT can automatically select the most suitable transmission gear ratio without any steps. Vehicles with CVT can run on the most efficient (i.e. with the best fuel combustion) engine rotation for regular velocity. The technology realizes seamless performance without shift changes when accelerating and decelerating.

It also expands the low-to-high gear ratio range, with transmission gear ratio control matching the way you drive, and delivering both excellent fuel economy and acceleration performance.

Technology Configuration

CVT adjusts the width of two pulleys and changes the arc radius of the steel belt running between them in order to control the transmission gear ratio.

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In the illustration above, the arc radius of the belt for the engine shaft pulley gets narrower. This is ideal for driving at slow speeds, when gears on MT or AT vehicles are lower (for example, first or second gear).

On the other hand, when in high gear, the belt on the drive pulley gets wider. This is suitable for high-speeds when the gear is high, such as in fifth or sixth.

The steel belt is serving here to bridge the two pulleys and change the diameter.

If the gear ratio at low gear is lowered even more, acceleration improves. This is the same as how starting in first gear has more power than starting in second. As well as when moving off, vehicle response improves at lower speed.
Expanded gear ratio range
On the other hand, when the gear ratio runs at a higher gear, the engine rotation decreases even at high speed, meaning there is better fuel combustion and less noise. This is the same logic as how when driving on a highway in fifth gear the engine rotates less than fourth gear.

Accordingly, in addition to the acceleration, the fuel combustion and engine noise levels can be improved by making the low and high gear ratio range (called transmission gear ratio range) larger.

XTRONIC CVT widened the low-to-high gear range of the transmission gear ratio through upgrading the pulley and steel belt, and the performance of the ATF (Automatic Transmission Fluid).

For 1.5-2.0-liter transmission it realizes top level gear ratio range.

The system is able to reduce transmission time by around 30%, realizing immediate response when you step on the accelerator pedal, and natural, powerful acceleration.
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*Gear ratio range: The ratio spread from low to high gear. The low gear ratio divided by the high gear ratio.

With CVT the engine output is transferred via the torque converter. The torque converter is configured with an ATF and along with working like a clutch, is an important vehicle part for increasing torque and transferring powerful kinetic force when moving off. However, by going through the ATF efficiency decreases, and the fuel combustion also becomes poorer.

After take off and when the torque converter's functions are not needed, the most ideal situation is to run the engine without going via the torque converter (so-called “locking up”). The XTRONIC CVT was the first such system in the world to apply a lockup damper.

By expanding the lockup range to lower vehicle speeds, the system realizes improved fuel combustion.

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NISSAN TECHNOLOGY MAGAZINE