This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Development of the Epicycloidal Roller Control System for the Torotrak Full-Toroidal Infinitely Variable Transmission
Technical Paper
2009-01-1540
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Application of high torque capacity Infinitely Variable Transmissions (IVT's) utilizing Torotrak variable ratio traction technology have delivered 20% fuel economy improvement in vehicles ranging from V8 SUV's to diesel city buses.
The fuel economy improvement results from a combination of optimised engine operation and significant reduction of launch parasitic losses by the replacement of the torque convertor with a “Geared Neutral” capability inherently provided by the IVT architecture.
The conventional Torotrak Variator comprises two toroidal cavities with three rollers per cavity. Each roller is attached to a reaction piston via a carriage assembly, resulting in the active division of the transmission load across the six available power paths. Hydraulic pressure is applied to each roller piston assembly, defining the torque reacted within the Variator.
Attaching each roller to a single control would not only reduce the parts count and cost of the transmission but would allow a drum output from the centre of the Variator so eliminating an epicyclic gear set and further simplifying the transmission design whilst improving its overall efficiency.
A novel Epicycloidal Roller Control (ERC) system has therefore been developed, connecting all six rollers to a single actuator by exploiting the inherent accuracy available from conventional involute gearing.
The result is a significant parts count and hence cost reduction together with improvements in system efficiency, performance and package.
This paper describes the ERC system in detail together with the testing and validation of the system.
Recommended Content
Citation
Brockbank, C. and Greenwood, C., "Development of the Epicycloidal Roller Control System for the Torotrak Full-Toroidal Infinitely Variable Transmission," SAE Technical Paper 2009-01-1540, 2009, https://doi.org/10.4271/2009-01-1540.Also In
References
- Burke M Briffet G Fuller J Heumann H Newall J “Powertrain efficiency optimization of the Torotrak Infinitely Variable Transmission (IVT)” SAE 2002 World Congress Detroit, USA Number 2002-03AC-75
- Lee A Newall J “Durability of a compact Dual-Cavity Full-Toroidal IVT Variator” SAE 2004 World Congress Detroit, USA Number 2004-10-0353
- Newall J Nicolson D Lee A Evans S “Development and Assessment of Traction Fluids for Use in Toroidal IVT Transmissions” SAE 2002 World Congress March 2002 Detroit; Michigan; USA Number 2002-01-0587
- Hewko L. O “Automotive traction drive CVTs – An overview” SAE paper 861355 1986
- Brockbank C Heumann H “Delivery of IVT for a 5 litre SUV: Addressing the concerns of Geared Neutral” IIR conference “Innovative Fahrzeuggetriebe” C1143 Bad Mergentheim March 2002