C O N T I N U O U S LY V A R I A B L E T R A N S M I S S I O N
XTRONIC CVT Technology Overview
Nissan’s 3rd generation “XTRONIC CVT” further boosts acceleration and fuel economy
CVT delivers enhanced fuel economy and seamless acceleration with a “direct” drive feel for enhanced AT driving pleasure.
CVT Advantages Exceptional transmission efﬁciency for enhanced fuel economy The CVT’s outstanding environmental performance and economy make this innovative technology ideal for today’s and tomorrow’s vehicles.
Smooth ratio transitions for enhanced driving pleasure Driving pleasure is enhanced by the linear feeling of acceleration in response to accelerator pedal inputs.
Nissan’s basic approach to powertrains is to achieve an equally high measure of both environmental compatibility (fuel economy) and driving pleasure (acceleration performance). For the XTRONIC CVT, our efforts to improve fuel economy were not conﬁned to catalog speciﬁcations, but encompassed the practical fuel efﬁciency people seek in everyday driving situations. For example, the majority of Nissan customers drive mostly in urban and suburban areas and about 60% run the air conditioner year-round. In developing the XTRONIC CVT, we enhanced real-world fuel economy based upon simulations of typical driving conditions.
Nissan offers CVTs in an extensive range of models Quick to appreciate the CVT’s beneﬁts of fuel economy and seamless acceleration, Nissan offered CVTs as early as 1992 in the March and Cube, followed by the 1.8-liter Primera and other models. Through technological innovation in CVT components, including the torque converter, oil pump, belt and control system, Nissan, in 2002, overcame the technological challenges to adapting the CVT to high-torque engines. The resulting XTRONIC CVT-M6 was the world’s ﬁrst CVT practicable for engine displacements as large as 3.5 liters. Today, Nissan’s CVT technology offers smooth and fuel-efﬁcient “fun-to-drive” performance in an extensive range of Nissan models, from the compact class all the way up to high-powered luxury vehicles. Seeking to bring the CVT’s outstanding performance to even more customers, Nissan plans to expand sales of CVT-ﬁtted models to around 1 million units worldwide in ﬁscal year 2007, up from about 250,000 in ﬁscal year 2004.
The CVT (Continuously Variable Transmission) provides smooth and “stepless” ratio changes, unlike conventional transmission systems that use sets of ﬁxed gears. With its seamless acceleration and fuel economy beneﬁts, the CVT has long been an object of Nissan’s R&D efforts, resulting in CVTs designed for a wide range of engines, from the 1.5-liter class to the 3.5-liter class.
Better fuel economy for everyday driving
CVT for 3.5-liter class engine
Congested trafﬁc Suburban trafﬁc
Response optimized for real-world conditions
Powerful and satisfying acceleration feel
CVT for 2.0-liter class engine
CVT performance is characterized by stepless shifting and seamless acceleration. To reﬁne these advantages, we signiﬁcantly improved gear shifting response in the XTRONIC CVT to provide tighter tracking of accelerator pedal inputs, as well as quick and powerful acceleration. In line with our emphasis on everyday driving conditions, we concentrated less on full throttle performance, and more on quickly responsive acceleration and smooth passing ability in urban trafﬁc.
Conventional CVT XTRONIC CVT
Seamless acceleration Improved response and efﬁciency Improved dynamic performance and powerful acceleration feel 2
Accelerator pedal depressed
CVT for 1.5-liter class engine
Enhanced acceleration feel
XTRONIC CVT Technology Overview
Improved response and efﬁciency
Stepless shifting of gear ratios eliminates “shift shock” for a smooth driving experience.
Wider ratio spread and more precise control for outstanding acceleration and fuel economy.
1. Wider gear ratio range
The CVT is an automatic transmission that uses two pulleys with a steel belt running between them. To continuously vary its gear ratios, the CVT simultaneously adjusts the diameter of the “drive pulley” that transmits torque from the engine and the “driven pulley” that transfers torque to the wheels. Because it is continuously variable, the CVT not only avoids the shift-shock and peaks and dips in torque transmission associated with a conventional AT, but also maintains optimum torque for any given power demand. This makes the CVT an exceptional transmission solution that delivers smooth and powerful driving performance together with excellent fuel economy.
Low gear Narrowing (diameter increases)
To Driveshaft Widening (diameter decreases)
In the XTRONIC CVT, the gear ratio range* from low to high gear is expanded, attaining a top-ofclass ﬁnal gear reduction ratio of about 6, thanks to pulley and steel belt improvements and the use of high performance ATF (Automatic Transmission Fluid). This ratio spread is among the world’s widest for a CVT designed for use with 1.5-liter to 2.0-liter class engines. We extended the low end of the range to improve acceleration, and the high end to improve fuel economy. In addition, the Nissan CVT is easily and ﬂexibly tunable to match engine characteristics, thereby enabling optimization of the balance between combustion efﬁciency and acceleration.
Low gear Smaller drive pulley radius raises acceleration performance
*Gear ratio range: The ratio spread from low to high gear. The low gear ratio divided by the high gear ratio.
Smaller driven pulley radius enhances fuel economy
Widening (diameter decreases)
Belt From Engine
Engine class To Driveshaft
Narrowing (diameter increases)
Gear ratio Low gear
Low gear Improving acceleration
Ring Multi-layer high-tensile strength steel
High gear Improving fuel economy
Element 400 highly rigid elements Vehicle speed
Expanded gear ratio range
XTRONIC CVT Technology Overview
Improved dynamic performance and powerful acceleration feel Responsive to the driver’s intention with a natural feeling of acceleration.
2. Wide lockup range
Quicker CVT shift response
Lockup* of an automatic transmission’s torque converter enables manual-transmission-like direct transfer of engine power and improved fuel economy. Whereas a conventional AT locks up in the mid-to-high speed range, the beneﬁt of a torque converter in a CVT is only during startup. Therefore, the new XTRONIC CVT applies precise control of ratio changes to extend the lockup operating area even further into the low-speed range and thereby boost fuel economy.
*Lockup: The condition in which torque from the engine is transferred directly to the pulley, without being affected by the torque converter. Belt
XTRONIC CVT Conventional CVT Engine speed
Elapsed time Accelerator pedal depressed The XTRONIC CVT shifts quickly to the optimum gear, and the engine speed rises rapidly.
We improved the electronic control system and the hydraulic system components under its control. In addition, adoption of a new high-performance ATF (Automatic Transmission Fluid) enhances response and stability. As a result, the CVT shifts ratios about 30% faster than the previous version. Furthermore, the new XTRONIC CVT controls shifting so that, up to a point, engine rpm will rise along with vehicle speed. As a result, Nissan’s CVT technology provides a more pleasurable driving experience, with nearly instantaneous response and a feeling of naturally powerful acceleration, as well as dependable engine braking.
CVT shift control allows the engine speed to rise naturally with vehicle acceleration.
Expanded lockup range with new XTRONIC CVT Drive pulley AT lockup range
New XTRONIC CVT expands lockup range
Torque converter in a CVT
3. Comprehensive efﬁciency improvements
Elapsed time Accelerator pedal depressed
Downsized, more efﬁcient oil pump The oil pump, which is the source of hydraulic power for shifting and assuring torque transmission, has been substantially downsized and made more efﬁcient. This helps maintain control capability that closely follows accelerator pedal action, while boosting fuel economy. For Nissan’s 2-liter class CVT, we adopted a compact chain drive, which contributes to downsizing of the transmission system as a whole.
The vehicle accelerates as soon as the driver presses the accelerator. Powerful acceleration is obtained immediately at any driving speed. Sustained power delivery allows the vehicle speed to rise smoothly. Drive chain
XTRONIC CVT offers rapid shifting
Reduced hydraulic pressure for pulley control We improved the precision of the control system used to shift the diameters of the two pulleys, so that sufﬁcient lateral pressure on the belt can be maintained with lower hydraulic pressure. This achieves reliable torque transfer together with high efﬁciency, thereby contributing to improved fuel economy. 6
Downsized high-efﬁciency oil pump with drive chain