Nissan and JATCO Develop Next-Generation CVT
22 July 2009
| Next-generation CVT. Click to enlarge. |
Nissan Motor Co., Ltd., and its affiliate transmission supplier JATCO Ltd. have jointly developed a new generation of compact and lightweight continuously variable transmissions (CVTs).
The next-generation CVT design features an innovative structure combining conventional CVT belt operation with an auxiliary gearbox and a significantly increased gear ratio range. The new CVT is scheduled to appear in compact Nissan vehicles worldwide in the near future.
Major features of the new CVT are:
High transmission ratio for quicker starts and acceleration. The new structure raises the available transmission ratio from current 6.0:1 to 7.3:1, more than 20% higher than other CVTs, for enhanced responsiveness on starting and acceleration. The 7.3:1 ratio is higher than the average conventional 7-speed automatic transmissions used on high-displacement engine-equipped vehicles, making it among the world’s highest ratios for production vehicle use (excluding DCTs and manual transmissions).
Compact and lightweight. This CVT configuration combines a belt-operated CVT with an auxiliary transmission, shortening its overall length by 10% and reducing weight by 13% compared to conventional CVTs in its class.
Drivability. The next-generation CVT features the Adaptive Shift Control (ASC), which improves performance by automatically selecting the best ratio for startup, acceleration and uphill or downhill driving.
Nissan believes the CVT has very good potential as a leading technology for raising the fuel efficiency of internal-combustion engine systems. Nissan first began applying CVT technology in 1991 and has been continuously evolving CVTs, engine-cooperative management and other systems, and expanding their use in Nissan vehicles. The need to improve fuel economy, with the resulting reductions in CO2 emissions motivated us to step up our efforts in the joint development with JATCO of this next-generation CVT.
—Shuichi Nishimura, corporate vice president, Nissan Powertrain Engineering Division
JATCO, the world’s leading CVT manufacturer, uniquely offers a full range of CVTs for applications from mini-vehicles up to 3.5-liter V6-equipped cars. The company produces 43% of CVTs made globally.
The revolutionary structure of the next-generation CVT, with its auxiliary transmission, not only raises the transmission ratio, reduces weight and adds fuel efficiency, its compact design also expands its applicability to a broader range of vehicles. We believe it is an excellent choice for automakers seeking to raise the fuel efficiency of their smaller cars.
—Yo Usuba, vice president, JATCO
Nissan and JATCO have achieved sales of 1 million CVT-equipped vehicles, as well as introducing 7-speed automatic transmissions to improve fuel efficiency.
This may prove to be a godsend for of all people... Chrysler. Chrysler uses the present generation of JATCO CVTs with their poor gear ratio range, as a substitute for the 6&7-speed, dual-clutch automatics that originally planned to use. Chrysler simply ran out of money to complete their new transmission factory.
When they were forced to substitute the poor gear range JATCO CVT, they had to over-cam their World engine, I-4s from a lauded refined item as Hyundai uses, into a "peaky" low torque at low rpm, noisy, apparent powerless, poor NVH, monster.
As part of their plans they were preparing a DI version of the I-4, to boost real HP and allow a return to relaxed and normal cam profiles, and perhaps to find a way to finish the transmission factory, and build 6 & 7 speed dual-clutch manual automatics.
Any or all of these changes plus a mild restyle on the Sebring offered as a MCE, would immediately change the reviews and acceptance of the Caliber, Compass, Patriot, Avenger and Sebring.
It would make the wait for new Fiat designs more bearable.
Posted by: Stan Peterson | 22 July 2009 at 07:02 AM
Why not go hydraulic? No transmission and much simpler.
Is there a weight issue?
Posted by: ChicagoBob | 22 July 2009 at 01:26 PM
Stan
I've always been interested in your opinion because you think like a practical person or engineer.
I'm a Chrysler engineering retiree and the info that I have received from people at Chrysler is that they are using the Gen 2 JATCO CVT and to the best of my knowledge I believe this new CVT with auxiliary transmission is Gen 4.
My wife is driving a Caliber and my daughter has a Patriot with the same CVT. These vehicles have relatively poor highway fuel economy and some of this is due to the fact that Chrysler Engineering did not like the way the vehicle ran with the Nissan suggested engine speeds so they retuned it to give the feeling of a conventional steped transmission. This had a negative effect on the highway fuel economy rating. This CVT is scheduled to be retuned for the 2010 model year but the new fuel economy ratings have not yet been posted on fueleconomy.gov but I expect them to be there by September.
The Sebring/Avenger vehciles use the old 4 speed automatic transaxle, a descendant of the old A604. They are the only midsize cars with 4 cylinder engines that don't have a 5 or 6 speed automatic transmission. Some time before their introduction Chrysler's Product Planning boss Eric Ridenour made a statement to the press that the 4 speed automatic would be adequate until the 2012 model year replacement. It is obvious that he was wrong and I suspect that he knew it was a lie but he was covering for Daimler who was in the process of selling Chrysler and didn't want to invest several hundred million dollars in a new transaxle. I recently rode in a Chevrolet Malibu with 2.4 liter engine and 6 speed automatic. At 70 MPH the Malibu was only turning about 2,000 RPM where as my Sebring with 2.4 liter engine and 4 speed automatic is turning 2,400 RPM at 70 MPH.
The 4 cylinder engines are being modified for the 2011 model year and will probably have a direct injection version. I've been told that Chrysler expects improved fuel economy and better NVH with these revised I4 engines.
I don't know what happened to the 6 speed dual clutch transaxle that was scheduled to be mated with the V6 engines for the 2010 model year but the agreement with Getrag for dual clutch components fell apart. Whether that dual clutch transmision could fit into the smaller engine compartments of the vehicles with I4 engines is a question I can't answer and I haven't seen anything about it on Allpar.com
rca
Posted by: rca | 22 July 2009 at 05:15 PM
A few years ago I was thinking of buying a new Jeep and was looking into the CVT models which looked good. But then my search, which had a very high emphasis on fuel economy, brought me to electric cars. Hence, I will now wait a few years, going carless or renting one or joining the auto coop if I need one, until good EV's come out.
I am SOOOO glad I didn't buy a Chrysler product. Today my friend brought in his Cherokee to the dealer because the back door wouldn't open and without even looking at the car the guy looked up in the computer the problem and I guess there is a whole list of problems with these vehicles so he said, "aha, this problem is this" and it gave a whole list of things to repair --- every related latch and cable, total cost over $1000..... to fix a rear door they hadn't even looked at, on a $5000 car. He said, "No wonder you're going out of business" and left.
So we cut off the back paneling on the door to get to the actuator mechanism and jiggled some wires and then it worked. But then after 2 hours it broke again but we know where the problem is so we'll be able to figure it out. And it turns out the actual faulty equipment piece wasn't even listed on the invoice produced by the computer so they would have had to add even more to it!
Chrysler ...... never again...... I value my money.
Posted by: Mark_BC | 22 July 2009 at 07:21 PM
I can't support any automotive technology that doesn't apply or isn't applied to hybrid and plug-in hybrid drivetrains. The notion that cars should be used for frivolous performance and leisure motoring is indicative of humanity's worst impulses. If GM and Chrysler went out of business, we'd all be better off. Better to begin learning how to live without our golem now, than to wait until it turns on us in a destructive fury.
Posted by: Sirkulat | 22 July 2009 at 07:22 PM
Why does not someone build a modern version of George Constantinesco's transmission with modern materials. George did design an aircraft machine gun firing mechanism that saved many lives during WWI. Perhaps his hydraulic mechanisms should be used as well again. ..HG..
Posted by: Henry Gibson | 25 July 2009 at 12:49 AM