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The New Generation XTRONIC CVT

CAR TECHNOLOGY

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CVT for the new age, combining environmental and sporty drive performance

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.

The New Generation XTRONIC CVT is suitable for 2.0-3.5-liter displacement engines, achieving an improvement in fuel economy of up to 10% compared to standard CVT, and delivering the feel of a more direct drive.
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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 rpm for regular velocity. The technology delivers seamless performance without shift changes when accelerating and decelerating.

The low-to-high gear ratio range is expanded, delivering a significant reduction in friction and up to 10% improvement from the previous generation. CVT. Further, the optimal transmission control makes for a drive that is intuitive, with a superb driving performance.
Technology Configuration

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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.

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 similar to starting in first gear with more power than starting in second. Vehicle response improves at lower speed and take-offs.

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.

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Through a narrower pulley axle and newly developed belt that works with this, the New Generation XTRONIC CVT has expanded the transmission gear ratio range from the previous cover of 6.0 to a global top level of 7.0

Nissan went back to the basic machine design, making efforts to reduce the CVT friction, reviewing approximately 300 CVT components out of the total of approximately 500. In addition to this, the size of the oil pump could be made smaller thanks to the reduction of oil leakage and this, together with the use of a newly developed low viscosity oil, reduced CVT friction by up to 40% and upgraded fuel economy.

The New Generation XTRONIC CVT is also characterized by its adaptive shift control, which interprets the driver intentions from the acceleration and steering to provide optimum shift control. Coordinated control between engine and transmission delivers optimal fuel consumption performance and driving performance.

 

NISSAN TECHNOLOGY MAGAZINE