Friday, 24 June 2016
CVT sales to reach 12 million - Torotrak
Torotrak Group claims sales of CVTs could reach 12 million by 2020 and has designed a variator with a ratio spread of 12 for front- and rear-wheel drive vehicles to meet future demand. The design has been proven up to 300kW.John Fuller, director of Concepts & IP for Torotrak Group, says by combining the company's extensive experience in main drive and auxiliary drive transmissions, it has come up with a scalable variator concept with a ratio spread of 12, operated by a low-cost actuation system.
“Market preferences are shifting from conventional automatics to CVTs,” claimed Fuller. “Our solution can accelerate that trend by satisfying the needs of front wheel drive but also potentially rear wheel drive layouts, where the high torque levels and packaging constraints can be more challenging for conventional CVT technology.”
Torotrak Claims its experience of auxiliary drives has led to reductions in system cost, in particular through cost-effective variator ratio control using the company’s PitchSteer technology. In this context, Torotrak is making use of patents it hopes will provide future income as royalties.
This enables a wide transmission ratio range to improve vehicle efficiency in various ways: firstly, by reducing the amount of energy dissipation when pulling away from stationary and secondly by enabling the engine to run at lower speeds when cruising.
Furthermore, the wide variator ratio spread enables simple and efficient transmission designs which maximise the use of ‘power splitting’, claims Torotrak. Thus only a fraction of the motive power is transferred by the variator, the remainder being transmitted by a direct mechanical path.
The transmission can also be configured as an IVT (Infinitely Variable Transmission) with a ‘geared neutral’. This can further improve fuel economy by removing the need for an inefficient vehicle launch device which loses power as it slips.
The system may be arranged to suit driver preferences in individual markets, for example to give the familiar driving sensation of a torque converter.
Fuller says electric vehicles (EVs) could benefit from the latest variator developments
"By increasing the wheel torque at low vehicle speeds, a toroidal CVT can improve gradeability and performance, or be an enabler for a downsized electric powertrain that is lower in cost and weight,” he said.
“With the CVT configured to achieve efficiencies in excess of 95 per cent, there is also potential to increase EV range”, Fuller further claimed.
The Torotrak Group of Leyland, Lancashire, UK, has examined the impact that toroidal CVTs and IVTs could have when used in autonomous vehicles. By providing continuous drive torque through seamless shifting, the technology is able to overcome the unpleasant sensation of torque interruption, to which occupants of such vehicles are highly sensitive.