Nissan Cvt Transmission
The Continuously Variable Transmission (CVT) allows engines to work at their greatest potential by freely moving through gear ratios to maximize performance and fuel economy. The advantage of the CVT is that it can choose the optimum transmission gear ratio. Solid gears are a thing of the past. The CVT uses the readings of multiple sensors to keep the engine rotating at a precise number of RPM with two variable pulleys and a steel belt. The system consists of seven smaller systems, including the vehicle’s mechanical, electrical, and oil systems, to provide fuel efficiency and continuous power. The following information on the CVT will guide you through its history, the systems and components involved and their operation.
Our Nissan CVT transmission sale has begun. The CVT or Continuously variable transmission utilizes a revolutionary design that eliminates the process of gear shifting. This is a one speed transmission with an endless amount of gear ratios allowing the CVT to have smooth seamless acceleration and increased efficiency. Nissan teamed up with Jatco. Nissan first opted for a CVT transmission in the Nissan Murano in 2002. The company did that to improve the fuel economy of the crossover and lower the emissions. The CVT transmission always keeps the engine at its most efficient revolutions – there is an infinite number of ratios.
HISTORY AND EVOLUTION OF CVT
The first visionary that conceptualized a stepless, continuously variable transmission was none other than painter, architect and inventor Leonardo da Vinci. He first sketched a stepless, continuously variable transmission in 1490.
In the centuries that followed, Adiel Dodge received a U.S. patent for a toroidal CVT. It still took years before the continuous variable transmission idea was brought to fruition in sawmills, tractors and motorcycles. Nissan® first used the CVT in the 1992 March, which was a super mini car also known as the Micra. The cube® and the Primera, which was introduced as the Infiniti G20® in North America, also ran with CVTs. After extensive research and development, Nissan developed a CVT that would run in high-torque engines in 2002. Nissan introduced the Xtronic CVT® with the release of the Murano in 2003. It was designed to provide smoother, quieter, and virtually shift shock free transmission performance at higher MPG than the traditional A/T. Now, the Xtronic CVT is found in all of Nissan’s front-wheel drive car models.
Nissan has continued making design changes ever since the CVT first hit the streets in North America. The newest models of this transmission are lighter and shorter and utilize optimum hydraulic control technology, which has enabled their use in a wider range of vehicles. They also have a broader gear ratio range by an entire gear, up to 7.3:1 in some vehicles from 6.0:1, providing fuel efficiency at a greater range of speeds.
CVT BASIC OPERATION
Nissan’s Xtronic CVT is a complex system that involves the use of sensors from the combination meter, the gear shifter and under the hood on both sides of the vehicle.
It is important to understand gears before we move forward. The rotating axes on a bicycle are gears. Imagine the bicycle with just two gear axes, both capable of expanding or contracting to the size of the largest and smallest gears that were on the bike, and you have imagined a continuously variable transmission. The CVT’s gears are capable of changing rotational direction, changing the speed of rotation, and optimally pairing the rotational speeds of the two axes.
When the driver presses the accelerator pedal, this sends a slew of signals to the CVT’s control valve assembly and the Transmission Control Module (TCM). The TCM controls the oil pressure system, which has two valves that control line pressure. The other signals are translated to voltages to activate the entire transaxle, including two variable pulleys and one steel-plated belt. The pulleys constantly adjust themselves to stay in the proper ratio. At around 5 MPH (8 km/h), the lock-up converter and the select control system engages, reducing slippage to get the best possible fuel efficiency. Contributors to the CVT’s functionality include the pulleys, belt CVT control valve assembly, shift lock system, oil pressure control system, fluid warmer system and the lock-up and select control system.
CVT SYSTEMS – Transaxle
Pulleys and Belt – The two pulleys and the belt are the heart of the CVT system. The primary, or drive pulley, connected to the engine lies on the input shaft side. The secondary, or driven pulley, lies on the output shaft side to the drive wheels. There is a cone-shaped slope on the fixation sheave half of the pulley that works with the slope on the mobile sheave halves that can move in the axial direction.
The movable sheave slides on the shaft to change the groove width of the pulley. As the pulley sheave halves come closer together and the width of the pulley changes, the belt is forced to ride higher on the pulley, effectively making the pulley’s diameter longer. Changing the diameter of the pulleys varies the transmission’s ratio (the number of times the output shaft spins for each revolution of the engine). Making the output pulley diameter longer gives a low ratio (a large number of engine revolutions producing a small number of output revolutions) for low-speed acceleration.
Nissan Cvt Transmission Reliability
Input signals of engine load (accelerator pedal opening), primary pulley speed and secondary pulley speed change the operation pressures of the primary pulley and the secondary pulley and control the pulley groove width. As the car accelerates, the pulleys vary their diameter to lower the engine speed as the car speed rises, continuously varying the ratio.