CVT- Continuously Variable Transmission
a) What's the purpose of CVTs? | To vary the transmission ratio continuously. |
b) How do CVTs work? | It depends on the CVT type:
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c) How do CVTs improve efficiency? | They allow the engine to operate allways in it's optimum R.P.M., whatever the vehicle's speed. |
d) What are the benefits of operating in the optimum R.P.M.? | 1.lower consumption; 2.less greenhouse gas emissions; 3.better performance; |
e) CVT is the ideal transmission, so why are there so few CVT cars? | The existing inventions are based on 1.friction, 2.hydrostatic, 3.ratcheting which are all mechanical systems with inherent limitations, (compared to traditional transmissions). |
f) So, how to extract the full CVT potential? | A conceptual innovation is the only way out. Although, research continues improving the friction CVTs and ratcheting CVTs, these efforts are acomplished by expensive high tech materials and precision manufacturing. This is to overcome the inherent limitations of these concepts (friction and ratcheting). |
Friction CVTs:
Definitions:
Notes on Continuously Variable Transmissions: http://www.gizmology.net/cvt.htm
A definition of CVT (by Greg Chandler): http://www.me.utexas.edu/~melingo/art/new/cvt.htm
Belt & V-pulley (friction CVTs)
Introducing CVT, by HONDA: http://www.honda.co.nz/site/technology/cvt_manual.html
Snowmobile friction CVTs: http://www.gates.com/brochure.cfm?brochure=1033&location_id=542
Honda Insight CVT: http://www.insightcentral.net/encyclopedia/encvt.html
Audi - Belt & V-pulley (friction CVTs): http://www.sae.org/automag/techbriefs_01-00/03.htm
Toroidal (friction CVTs)
Toroidal CVT by Torotrak, in United Kingdom: http://www.torotrak.com/howitworks.html
Toroidal CVT-Introduction to Advanced Technology:
http://www.jatco.co.jp/ENGLISH/PRODUCTS/s_tcvt.html
http://www.jatco.co.jp/ENGLISH/PRODUCTS/cvt.html
http://www.jatco.co.jp/ENGLISH/PRODUCTS/s_cvt.html
Milner Toroidal CVT: http://cvt.com.sapo.pt/MCVT/MCVT.htm
Hydrostatic CVTs:
HONDAMATIC © CVT: http://www.atving.com/editor/press/honda/hondamatic.htm http://www.motorsports-network.com/honda/201atv/rubcon01/tranny.html
SAE off-Highway Eng. (Inside Claas' CVT): http://www.sae.org/ohmag/toptech/01.htm
Ratcheting CVTs:
How do ratcheting CVTs work? http://cvt.com.sapo.pt/ratcheting/ratcheting.htm
The Crank CVT, by Luk.de:
http://luktest1.ina.com/content/media/_companydb/products/library/downloads/luk_k7_chap08.pdf
http://luktest1.ina.com/content/en/products/transmission_components/cvt/luk_kurbelcvt_sv/LuK_KurbelCVT_lv.jsp
Barloworld Universal Joint CVT: http://www.barloworld-cvt.com/products.html
Infinity Drives CVT: http://www.infinitydrives.co.za/
Zero-Max Adjustable drives: http://www.zero-max.com/products/drives/drivesmain.asp
Constantinesco Torque Converter: http://fluid.power.net/fpn/const/const005.html
Epilogics CVT: http://cvt.com.sapo.pt/ratcheting/ratcheting.htm
Positive-drive CVTs:
Anderson CVT: http://www.andersoncvt.com/
Gearing Up for CVTs - SwRI: http://www.swri.edu/3pubs/ttoday/summer00/cvt.htm
CVT control: http://cvt.com.sapo.pt/control/control.htm
How much does CVT benefit? http://cvt.com.sapo.pt/performances/performances.htm
CVT Enters the Mainstream: http://www.edmunds.com/ownership/techcenter/articles/45104/article.html
Integrated Powertrain Design and Control: http://www.bath.ac.uk/~enscjb/integratedpowertrain.pdf
Audi takes CVT from 15th century to 21st century: http://www.sae.org/automag/techbriefs_01-00/03.htm
CVT Technology - SwRI: http://www.swri.edu/3pubs/brochure/d03/cvt/cvt.htm
CVTs/IVTs FORUM: http://cvt-ivt.tripod.com/
Reference info on CVT - http://cvt.com.sapo.pt
In the web site "How Stuff Works":
Gear Ratio: http://auto.howstuffworks.com/gear-ratio.htm
Transmissions: http://auto.howstuffworks.com/transmission1.htm
Automatic transmissions: http://auto.howstuffworks.com/automatic-transmission.htm
Torque converter: http://auto.howstuffworks.com/torque-converter.htm
Latest Developements in CVT Technology: http://luktest1.ina.com/content/media/_companydb/products/library/downloads/luk_k7_chap05.pdf
Trendy Transmission Facilitates Shiftless Lifestyle - CVT's Coming on Strong http://www.technofile.com/cars/cvts.html
Toroidal CVT by Torotrak: http://www.torotrak.com/
Luk - German transmission Researcher & Manufacturer: http://www.luk.de/content/en/index.jsp?
Audi multitronic transmission: http://www.audiworld.com/news/100699.html http://www.audiworld.com/news/99/multitronic/content.shtml
Honda Civic CVT Hybrid: http://www.technofile.com/cars/honda_civic_hybrid.html http://www.roadandtravel.com/roadtests/reviews/2003roadtests/hondacivichybrid.htm
Honda Insight: http://www.insightcentral.net/
Mini - (BMW) http://www.sae.org/automag/globalvehicles/08-2001/index.htm
Snowmobiles use CVTs: http://www.gates.com/brochure.cfm?brochure=1033&location_id=542
Note: there are more links in the CVT control page.
DAF - Belt & V-pulley (friction CVTs):
the variomatic transmission http://www.classic-daf.nl/indexb.html
DAF Formula One: http://www.ritzsite.demon.nl/DAF/DAF_cars_p17.htm
Volvo with DAF variomatic CVT http://www.volvoclub.org.uk/prof_cvt.htm
Some 40 years ago: http://www.auto-asia.com/trends/20000202001.shtml
Ratcheting CVTs:
Constantinesco Torque Converter: http://fluid.power.net/fpn/const/const005.html
CVT have been used in sports too:
DAF: http://www.ritzsite.demon.nl/DAF/DAF_cars_p17.htm http://www.rallydaf.nl/
Williams Formula One: http://www.cke-tech.com/cvpst.htm (see the bottom of this page)
Honda Civic CVT: http://www.rallyracingnews.com/teams/pr-thr2.html
CVT Forum: http://autos.groups.yahoo.com/group/cvtcontinuouslyvariabletransm/
CVT Forum links: http://www.mybookmarks.com/public/cvt
[created: 16 Mar 2003, updated: 19 Set 2008 ] [ designed by vb.web.pt ]