Our mechanical cvt offers a costeffective solution for many agricultural, offhighway and industrial applications. Then, the features and applications of the most popular kinds of continuously variable transmission, i. Instead, the hydromechanical threespeed transmission was selected, and. Continuously variable transmission friction drive figure1. The main topics in this case relate to a very simple and easy design, which allows a. A vehicle equipped with a cvt can provide a very different driving experience. Toroidal cvt continuous variable transmission explained with animation. Download pdf double roller full toroidal variator cvt ivt transmissions when a cvt and a secondary planetary gearset are coupled together it is possible to create a transmission that provides reverse gears, geared neutral, and forward gears without the necessity of a clutch to disengage the wheels from the driving motor.
Toroidal continuously variable transmission systems. The toroidal cvt is socalled because a part of a curved surface at the inner side of two disks constitutes the shape. Toroidal cvts the simplest toroidal cvt involves two coaxial disks bearing annular groves of a semicircular cross section on their facing surfaces. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. Infinitely variable transmissions using a toroidal. Autotronic continuously variable transmission cvt was developed specifically for the powertrain of the aclass. Kers transmission system as the torotrak variable drive system is torque controlled, the variator transfers the energy to and from the flywheel irrespective of the speeds of the driveline of the flywheel. Current efforts to decrease the vehicles fuel consumption in order to. Now, nissans latest accomplishment is the extroid cvt for application to rearwheeldrive cars powered by 3. Particularly in terms of comfort and fuel consumption, this transmission sets new standards in the compact car class. Back in the 1930s, and later in the 1970s, general motors patented a toroidal traction drive effectively a cvt and came close to offering a toroidal automatic transmission in the 1937 buick and again in the 1980 pontiac. Design, analysis and control of a spherical continuously.
Finally, a continuously variable transmission that makes sense. Structure of transmissions on the other hand, continuously variable transmission cvt is preferable because the reduction ratio continuously varies and it maintains the operating condition of. A continuously variable transmission cvt transfers power through a range of speedtorque ratios from engine input to output, continuously without interruption. The toroidal cvt is an innovative transmission that executes smooth, continuous gear ratio changes by changing the angle of the power rollers between the input disk and output disk. Disadvantages of continuously variable transmission 1. An electromechanical servo can switch the cvt drive through its full 10to1 ratio spread in only 0. Some more detail about toroidal cvt another version of the cvt the toroidal cvt system replaces the belts and pulleys with discs and power rollers.
One hundred years later, nsk undertook its development in 1978, spending as much as 21 years to develop a practical application. A continuously variable transmission cvt, also known as a shiftless transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a twistandgo, is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. Instead of the conventional toothed gears found in traditional transmissions, the toroidal variable transmissions tvts. Introduction a continuously variable transmission cvt, conversely, is a type of transmission that allows an infinitely variable ratio change in a finite range, thereby allowing the engine to continuously operate in its most efficient or highest performance range. Toroidal type continuously variable transmission inventor. Toroidal cvt powertoros unit automotive products nsk. A half toroidal continuously variable transmission cvt has a large torque capacity, vastly exceeding that of conventional cvts, and has attracted attention as a technology capable of providing both substantially improved fuel economy and power performance. The infinite number of ratios provided by the transmission enables the power equipment to do more work, with less fuel, in less time. Toroidal variator transmission free download as powerpoint presentation.
Off to the races with a liquidsolid cvt transmission. The familiar twin cavity compact lever roller control design of torotraks full toroidal variator is. Figure 1shows an example of the structure of the full toroidal cvt. The most common type is the pulleybased, but some other types include the toroidal cvt, which uses rotating discs along with power rollers to produce the same result as the pulleys. A first output shaft can be connected to the output of the first toroidal variator, and a second output shaft can be connected to the output of the second. Cvt seminar pdf report with ppt cvt theory a typical automatic uses four or. Performance evaluation of ball cvt and comparison with. Cvt is a transmission that can shift harmlessly through an infinite number of impressive gear ratios between maximum and minimum values. Design of continuously variable transmission cvt with.
Pdf toroidal continuously variable transmission systems. Koyos approach to continuously variable transmissions. A continuously variable transmission cvt, also known as singlespeed transmission, gearless transmission, onespeed automatic, variable pulley transmission, or in case of motorcycles, a twistandgo is a transmission that can change seamlessly through an infinite number of effective gear ratios between maximum and minimum values. Worlds first 1motor, 2clutches type transmission for hybrid vehicles 2010 steel belt cvt for 2l class 1997 toroidal cvt 1999 cvt for 3. Fulltoroidal variable drive transmission systems in. However, for this type of cvt to display its unique features to their fullest extent, it is essential to raise its power. This b cvt has a simple kinematic structure, and same as a toroidal cvt, transmits power by friction on the contact points between input and output discs, that are connected to each other by balls.
It had no practical applications because at that time it was a dry friction transmission, although attempts were made to use it. An infinitely variable transmission ivt is a subset of a cvt continuously variable transmission defined as a device that has a range of ratios of input shaft speed to output shaft speed which includes an infinite ratio in which the output speed is zero. Although such a system seems drastically different, all of the components are analogous to a beltandpulley system and lead to the same results a continuously variable transmission. This type of transmission systems are used in vehicle withautomatic. Full toroidal cvt in a kinetic energy recovery system chris brockbank bsc hons torotrak development ltd 1. Other development emphases include higher output, higher torque, more driving pleasure and very compact dimensions. Toroidal engine, an internal combustion engine with pistons that rotate within a toroidal space toroidal cvt, a type of continuously variable transmission toroidal reflector, a parabolic reflector which has a different focal distance depending on the angle of the mirror. Cvt cvt allows for the operation at the lowest possible speed and highest possible load, partially avoiding the low efficiency region of the engine map. This paper concerns the design and analysis, of a ball type continuously variable transmission, b cvt. Continuously variable transmission system inventor. The cvt is a continuously variabletransmission system. Typically these devices include both positive and negative ratios on either side of zero resulting in the ability to move forward and. A toroidal transmission, especially for motor vehicles, comprising an input shaft which can be connected to an engine, a first toroidal variator and a second toroidal variator which are connected to the input shaft on the input side.
Multipurpose continuously variable transmission fluid product description mobil cvtf 3320 is high performance, continuously variable transmission fluid designed to meet the service fill use for many japanese designed vehicles. Design, analysis and control of a spherical continuously variable transmission by jungyun kim. Sumit thakur mechanical cvt seminar and ppt with pdf report. A continuously variable transmission cvt transfers power through a range of speedtorque ratios from. The geometrical and kinematical aspects of this model have been found. Full toroidal cvt in a kinetic energy recovery system. The first patent was applied in europe of a frictionbased belt cvt by daimler and benz 1886, and a us patent for a toroidal cvt was granted 1935. Extroid cvt for application to rearwheeldrive cars. Leonardo da vinci 1490 developed a concept of staples continuously variable transmission. Cvt s are an automatic transmission type most often applied to automobiles. Also, due to the existence of a torque converter in cvt, the car starts smoothly and compared to manual transmission, in. A driver accustomed to using a traditional automatic transmission or manual transmission will not feel the engine in a cvt vehicle accelerating. Our proven and reliable technology is protected by more than 20 patent families worldwide.
Pdf design of continuously variable transmission cvt. They do not require a clutch, but only a locking ringdog clutch, the same as for the single speed. Nissans weird double cvt is perfect for hightorque applications you may be familiar with beltdriven continuously variable transmissions. Cvt with metal pushing belt and variable pulleys, toroidal cvt and hydrostatic cvt have. The 2009 seat exeo is available with a cvt automatic transmission multitronic. Traction drive system and its characteristics as power. When autoplay is enabled, a suggested video will automatically play next. Continuously variable transmission with two opposing biasing devices inventor.
This study aims at finding an analytical model of ball continuously variable transmission b cvt behavior and performance, based on the existing model of the half toroidal traction drive. Home most powerful mechanical cvt transmission cvtcorp. Another version of the cvt the toroidal cvt system replaces the belts and pulleys with discs and power rollers. Nissans weird double cvt is perfect for hightorque. Advantages and disadvantages of continuously variable. As a manufacturer specializing in transmissions for. Zenith motorcycles made a graduageared v2 engine motorcycle, that was a cvt. Then, forcemoment equilibrium equations have been applied for a b cvt. Introduction on the 28th july 2006, the president of the federation internationale lautomobile fia announced draft regulations for the recovery and reuse of energy on formula 1. Mobil cvtf 3320 provides smoother, consistent all weather stepless shifting, and all. Torotrak infinitely variable transmission articles.