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Automakers hope to save millions of dollars with joint development

Ford and General Motors have announced that they have teamed up to jointly develop a new generation of advanced 9- and 10-speed transmissions that will be used in cars, crossovers, SUVs, and trucks.
 
The automakers say that the new transmissions will increase both performance and fuel economy. Engineering and development work for the transmissions is currently underway.

“Engineering teams from GM and Ford have already started initial design work on these new transmissions,” said Jim Lanzon, GM vice president of global transmission engineering. “We expect these new transmissions to raise the standard of technology, performance and quality for our customers while helping drive fuel economy improvements into both companies' future product portfolios.”

Automakers need every edge they can get to meet the looming federal CAFE guidelines set to go into effect over the next several years. With a greater number of gear ratios available in the transmission, the engine can operate at more efficient RPMs, which in turn leads to improved fuel economy.
 
Some industry analysts believe that a nine-speed automatic transmission could increase fuel economy by five to ten percent compared to the same vehicle using a six-speed transmission.
 
The two companies have collaborated on transmission technology in the past. Ford and GM previously collaborated to build a six-speed transmission for front-wheel drive cars. Ford currently uses the six-speed transmission and vehicle such as the Fusion and Edge. GM uses the transmission in the Malibu and Cruze among others.
 
Chrysler is currently using an eight-speed automatic transmission in some of its automobiles, including its popular line of trucks.

Source: GM



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RE: Continuously Variable Transmission (CVT)
By yomamafor1 on 4/15/2013 12:45:30 PM , Rating: 2
Actually, CVT's efficiency hovers around 88~93%, where AT has efficiency of around 83%

http://www.zeroshift.com/pdf/Seamless%20AMT%20Offe...

This is why CVT variant of the vehicles get more MPG out of AT variants. I can't for the life of me understand why people think CVT is less efficient than AT.


By alpha754293 on 4/15/2013 1:27:08 PM , Rating: 2
DISCLAIMER: I am speaking for myself and not my employer.

yea...I don't know if I buy into the Zeroshift link. They have a cyclical reference (the source of their information points to another publication they wrote). That's about as reliable as someone saying "I am God" (claiming themselves). Which also raises the question - seriously? You couldn't find another source?

So I wouldn't put too much weight on that.

CVT efficiencies are HIGHLY proprietary info. 60-80% seems about right though from all the stuff that I've read.


RE: Continuously Variable Transmission (CVT)
By alpha754293 on 4/15/2013 1:55:08 PM , Rating: 2
DISCLAIMER: I am speaking for myself and not my employer.

It also depends on whether you are looking at the CVT itself or as the entire transmission system.

I found one SAE Paper (SAE 2005-01-1467) where the CVT that they modelled can be as high as 95% efficient (CVT only, although the graph is kinda hard to read), but as an entire system (power- and drivetrain), it only about 35% efficienct). You'll have to look up their paper for all of their modelling assumptions, but that's all that I've been able to find so far. (There are other papers from JSAE that I don't have access to so I don't know if it has better information there.)

Source: Kanphet, P., Jirawattana, P., and Boonsrang Direcksataporn. (2005.) "Optimal Operation and Control of a Hydrostatic CVT Powertrain", Khon Kaen University, Transmissions and Drivelines Symposium–4WD/AWD, 2005 SAE World Congress, SAE International. SAE 2005-01-1467.


RE: Continuously Variable Transmission (CVT)
By Colin1497 on 4/15/2013 3:56:57 PM , Rating: 2
As I recall, CVT efficiency falls off quite a bit as power goes up because you drive more friction into the system, so CVT's can be more efficient with low power engines but decline in efficiency rapidly as engine power increases.


RE: Continuously Variable Transmission (CVT)
By theKeener on 4/19/2013 8:55:46 AM , Rating: 2
I put 100,000 miles on 2003 Nissan Murano. That thing had a standard transmission fluid cooler in radiator, a stacked plate heat exchanger cooler that actually bypassed the engine (ie coolant can go through engine or transmission cooler) that was electronically controlled and a huge air scoop and fins on the transmission pan. I'm no expert but I would say that much heat in the fluid indicates it is less efficient than a standard automatic.

I researched them quite a bit before I purchased this car. The Xtronic CVT Nissan uses relies on a metal belt made up of a few steel cables and circular stack of interlocking trapezoidal metal plates. Torque is transferred on the push side of the belt. The best description I found was imagine pushing a rope, when pushed the rope becomes stiff. The metal plates interlock and the driven pulley is 'pushed' by the drive pulley. It's very ingenious and requires very careful control of the hydraulic pressure inside the two variable diameter pulleys the belt rides on.

CVT's by their very nature must rely on friction to transfer torque, hence the heat I imagine.

As far as my subjective opinion. CVT's dull the driving experience. I think they have their place in economy cars but not for enthusiasts or sport oriented driving. WOT acceleration is a painful, droning thrash stuck at 6500 rpm, ugh! The Murano was certainly fast enough for long distance travel and passing zones but not much fun on twisty roads. I'll take my old 5 speed M3 any day over this modern technology.

I'm glad to see more gears being developed. Solves the economy problem of needing a super overdrive gear without the soul-less droning engine you get with a CVT.

BTW, the torque converter lock up clutch in most modern automatics makes them almost as efficient as a manual at cruising speeds. We've had those for 15 years.


By alpha754293 on 4/19/2013 2:46:57 PM , Rating: 2
DISCLAIMER: I am speaking for myself and not my employer.

I'm not 100% sure on the Murano CVT thermal management design, but I can tell you this: car makers hate to put duplicate or redundant systems unless they absolutely have to. So if there are two coolers, chances are - there's a REALLY good reason why both would exist (and switching between one to another is probably also due to a REALLY good reason (out of necessity) and not because they feel like it.)

Yeah, that's pretty much how double conical CVTs work. (Sorry, I always keep thinking that that's just general knowledge, but maybe it isn't.) Uh...the pressure controller probably isn't as accurate as you might think is necessary.

The thing that people forget is that everything is designed with a reason/purpose in mind. If you're trying to hit 54.5 mpg with a 6-speed, it's going to be INCREDIBLY difficult for you.

The fundamental operating principle/reason why CVTs were invented was to always be running at the peak/optimial efficiency at a given load with a given torque output/transfer. It was supposed to be about peak efficiency, but people being people - were complaining about how they don't feel the shifts blah blah blah, so we had to change the shift program to deal with that and take it away from its true purpose.

I LOVE how people think that accelerating MUST mean that your revs change instead of revving the piss outta the engine while the torque is being transferred in a controlled manner. It's no different (in principle of operation) as slowly letting out the clutch on a traditional manual. *rolls eyes*...sigh....

CVTs make it "dull" because you can't have a discontinuous torque function. You don't get the abrupt changes in torque like you do with discrete gears. In theory, there's nothing that says that you can't design the control algorithm to allow for rapid changes to the conical controller, but you might end up with jerky shifting under normal operation (cruising), which now adds the complexity of having a variable pressure valve in the hydraulics which also now means you need a controller for the valve assembly AND the controller for the conicals. Which means extra cost. Which people don't want to pay for.

Some AMTs/SMTs have electrohydraulic clutch packs that make the entire transmission more efficient than traditional manuals. And they're also already working on an e-clutch (in case people here aren't aware of that). It's been going on for a few years actually.


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