It offers a ratio spread of around seven and requires a starting device such as a clutch or torque converter to launch the. Thereafter, traction drive toroidal cvts were developed and marketed for such uses as research in laboratories, bearings, oil, and cars. Introduction a continuously variable transmission cvt, conversely, is a type of transmission that allows an infinitely variable ratio change. Electric motor and inverter model in the specific implementation of this paper, the rear axle of each layout is powered by a 28 kw peak power permanent magnet pm electric motor, shown in figure 1a. Half toroidal cvt ht 22 872 full toroidal cvt ft 22 80872 ivt type i ivti 30 880 ivt type ii ivtii 30 880 2. A cvt is the simplest form of transmission to use a toroidal variator. Regarding the variable drive system, the f1 kers fulltoroidal variator of a 55 mm roller diameter with a ratio spread of 6. When this is done in a continuous manner, we get a continuously variable traction. The main topics in this case relate to a very simple and easy design, which allows a sufficiently quick and stable control. Pdf development of the inner spherical cvt for a motorcycle. Kinematics of the fulltoroidal traction drive variator journal of. The necessary parts and components for the cvt have been determined.
Toroidal reflector, a parabolic reflector which has a different focal distance depending on the angle of the mirror. 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. Extroid cvt for application to rearwheeldrive cars. Traction fluid is a key component of a tcvt, since it is responsible for power transmission in this type. Although capable of higher powers over the ratio range e. 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 study aims at finding an analytical model of ball continuously variable transmission bcvt behavior and performance, based on the existing model of the halftoroidal traction drive. What is a toroidal transmission nissan produced cedricgloria model with integrated cvt modification with the torque up to 370 nm and the engine with a power of 280 hp for the. Toroidal cvts are made up of discs and rollers that transmit power between the discs. Energy consumption of a battery electric vehicle with. A halftoroidal continuously variable transmission cvt has a large torque capacity, vastly exceeding that of conventional cvts, and has attracted attention as a technology capable of. The efficiency of the original toroidal continuously variable transmission cvt is limited due to the spin. The toroidal cvt is socalled because a part of a curved surface at the inner.
The efficiency of the original toroidal continuously variable transmission cvt is limited due to the spin losses caused by. It is used for automatic transmission in a few cars coupled to a hydraulic t. Utimate transmissions double roller full toroidal variator based cvt dftvcvt transmissions 4. Toroidal cvt powertoros unit automotive products nsk. Mockel, chemnitz in this contribution a new, very compact roller suspension for a toroidal cvt is presented. Another version of the cvt the toroidal cvt system replaces the belts and pulleys with discs and power rollers. Some of toroidal cvts are also continuously variable. Fulltoroidal variable drive transmission systems in.
To improve the efficiency of shaft drive cvt, the theoretical powertransmitted efficiency is examined in this paper. The ncvt adopted on the nissan march in 1992 was a beltdrive unit that utilized. 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. A comparison of the full and half toroidal continuously variable transmissions in terms. Koyos approach to continuously variable transmissions. This bcvt has a simple kinematic structure, and same as a toroidal cvt. The discs can be pictured as two almost conical parts, point to point, with. Full toroidal cvt in a kinetic energy recovery system. A toroidal transformer is donutshaped, with primary and secondary coils that are wound around a ferromagnetic core and often layered on top of one another. Pdf an inner spherical cvt iscvt transfers engine power by utilizing the traction.
Toroidal transformer design program with application to inverter circuitry by james a. It has a round iron core with a coil of insulated wire wrapped around it. Although such a system seems drastically different. Hydrostatic cvt this topic we will be studying about toroidal cvt. Performance evaluation of ball cvt and comparison with. This paper presents the trends of cvt and a brief overview of full toroidal ivt that koyo has been. Study and design of national institute of technology. The novel mechanism cvt shaft drive cvt, scvt was developed by the authors. The traction or toroidal continuously variable transmission tcvt is commonly used for traction drives in automotive applications.
Introduction on the 28th july 2006, the president of the federation internationale. Dynamic and tribological analysis of a toroidal continuously variable. A mathematical method for eliminating spin losses in toroidal. Toroidal, continuously variable transmission cvt, i. Research article a mathematical method for eliminating. Toroidal or rollerbased cvt extroid cvt toroidal cvts are made up of discs and rollers that transmit power between the discs. Toroidal cvt toroidal cvts are made up of discs and rollers that transmit power between the discs one disc is the input, and the other is the output they do not quite touch. In 1999, nissan and nsk were the first to massproduce a toroidal cvt for automobiles. Lewis research center summary users of this program are relieved of most. A toroidal transformer is a transformer shaped like a doughnut. Full toroidal cvt in a kinetic energy recovery system chris brockbank bsc hons torotrak development ltd 1. See the video in this topic for easy understanding. Department of trade and industry uk via the foresight vehicle project lamtrak researcher.
Traction drive system and its characteristics as power. And in toroidal cvt the direction of the thrust force can be reversed. A continuously variable transmission cvt, also known as singlespeed transmission, gearless transmission, onespeed automatic, variable pulley transmission, or in case of motorcycles, a. Toroidalcvt tcvt has recently been introduced as an alternative automatic transmission technology. Continuously variable transmissions cvt can cover a. The japanese and germans continue to lead the way in cvt development. Pdf this paper concerns the design and analysis, of a ball type continuously variable transmission, bcvt.
Design of continuously variable transmission cvt with. In this research a model is developed which calculates the torque transmission efficiency of a halftoroidal cvt as a function of variator geometry, gear ratio and input torque. The continuously variable transmission investigated in this paper works. The extroid cvt is also available with a 6speed manual shift mode that. Pdf traction and efficiency performance of ball type cvts. The first visionary that conceptualized a stepless, continuously variable transmission was none other than painter, architect and inventor leonardo da vinci. Pdf cvt ratio control strategy optimization researchgate. Full toroidal ivt variator dynamics sae international. Introduction this study describes a method for analyzing and designing a continuously variable transmission system cvt. Nissan has taken a dramatic step with its extroid cvt, offered in the homemarket cedric and gloria luxury sedans.