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Ford to Introduce Dry-Clutch Derivative of Dual-Clutch PowerShift Transmission in North America in 2010

Twinclutchtrans_53
The dual-clutch PowerShift transmission. Click to enlarge.

Ford Motor Company will introduce a dry-clutch derivative of the dual-clutch PowerShift six-speed transmission in North America in 2010 for the small-car segment.

The dual-clutch technology consists essentially of two manual transmissions working in parallel, each with its own independent clutch unit. One clutch carries the uneven gears (1, 3 and 5) while the other the even gears (2, 4 and 6). Subsequent gear changes are coordinated between both clutches as they engage and disengage for a seamless delivery of torque to the wheels.

Compared to traditional automatic four-speed transmissions, PowerShift can help reduce fuel consumption by up to 9% depending on the application.

In Europe, Ford currently offers a PowerShift transmission in the Ford Focus. This PowerShift uses a twin wet-clutch system to handle the higher torque levels of the 2.0-liter TDCI engine available in the Focus.

In North America, a dry-clutch derivative of Ford’s PowerShift transmission will be used for added efficiency and durability. A dry clutch transmits power and torque through manual transmission clutch facings, while most automatic transmissions utilize wet clutch plates submerged in oil. As a result, the dry-clutch PowerShift transmission does not require an oil pump or torque converter, providing superior mechanical efficiency.

A dry clutch is a real sweet spot for lighter vehicle applications. PowerShift is more efficient, it saves weight, is more durable, more efficient and the unit is sealed for life, requiring no regular maintenance.

—Piero Aversa, manager, Ford Automatic Transmission Engineering

PowerShift, unlike conventional automatic transmissions, does not need the heavier torque converter or planetary gears. In addition, the dry-clutch derivative eliminates the need for the weighty pumps, hydraulic fluids, cooling lines and external coolers that wet clutch transmissions require. As a result, the dry-clutch PowerShift transmission can weigh nearly 30 pounds less than, for example, the four-speed automatic transmission featured on today’s Ford Focus.

Differentiating PowerShift even further in terms of its customer appeal is its shift quality, launch feel and overall drive dynamic, which are all facilitated by a blend of Ford-exclusive electro-mechanical systems, software features, calibrations and controls. These driving features include:

  • Neutral coast down. The clutches will disengage when the brakes are applied, improving coasting downshifts and clutch robustness as well as reducing parasitic losses for increased fuel economy.

  • Precise clutch control in the form of a clutch slip to provide torsional damping of the engine vibration. This function improves noise, vibration and harshness (NVH) at low engine speeds and enables lower lugging limits for improved fuel economy.

  • Low-speed driving or creep mode with integrated brake pressure. This function simulates the low-speed control drivers are accustomed to from an automatic transmission. The amount of rolling torque in Drive and Reverse is precisely controlled, gradually building as brake pressure is released.

  • Hill mode or launch assist. Prevents a vehicle from rolling back on a grade by maintaining brake pressure until the engine delivers enough torque to move the vehicle up the hill, providing improved driver confidence, comfort, safety and clutch robustness.

With its improved fuel economy, PowerShift is a key enabling technology for Ford as it targets best in class or among the best fuel economy with every new vehicle it introduces in North America.

Overall, Ford has committed that almost 100% of its transmissions will be advanced six-speed gearboxes by 2013. Six-speed transmissions already have helped vehicles such as the 2010 Ford Fusion achieve best in class fuel economy, while at the same time allowing the Ford Flex and Ford Escape to achieve unsurpassed fuel economy in their respective segments. 

Ford is leveraging six-speed transmissions; advanced internal combustion engines such as EcoBoost; hybrids; full electric vehicles; vehicle weight reduction; and electric power-assisted steering to improve fuel economy and reduce greenhouse gas emissions fleet-wide by 30% by 2020.

Comments

Adam H

Well played.

Brian P

Manufactured by BorgWarner? It uses a very comparable mechanical layout to the VW DSG transmission, including the dual-layshaft arrangement with two different final drive ratios.

Lad

I see the advantage of fast-shifting, solid-mashing tyrannies; but, I am still worried about the drop of 15% between the engine power and tractable power caused by drive line losses. Wheel electric motors don't have these losses. Duel clutch tyrannies are neat and I would like to have one in my track car; but, they are not a long term answer and are of little value to direct electric drive autos. I would much better like to see the money placed in our future, which is electric drive cars, not ICEs. The continuation of high mileage ICEs is an interim step toward the future, not the future.

GdB

"drop of 15% between the engine power and tractable power caused by drive line losses"

Lad, I serious doubt manual or dry double clutch trannies loose 15%. More like 5% or less if they use low viscosity oil. "Driveline" includes engine ancilleries. Add a few more % loss for the diff.


Overall I like this, but a few comments:


"Neutral coast down. The clutches will disengage when the brakes are applied, improving coasting downshifts and clutch robustness as well as reducing parasitic losses for increased fuel economy."

So if you let off the gas for a second, than get on it hard, it will likely jerk.

A better strategy is to upshift and minimize engine parasitic drag. Diesel engines, cylinder shutoff, electric fuel, power steering, cooling, oil pumps all help here.


"Low-speed driving or creep mode with integrated brake pressure. This function simulates the low-speed control drivers are accustomed to from an automatic transmission. The amount of rolling torque in Drive and Reverse is precisely controlled, gradually building as brake pressure is released."

I hope the brake pressure is simulated, and not the brakes fighting the clutch. Also, I hope they make the 1st gear clutch long life. I could see some people who have to deal with real slow traffic everyday burn through a clutch real quick.

"Overall, Ford has committed that almost 100% of its transmissions will be advanced six-speed gearboxes by 2013. "

Great stategy to get costs down! Too many options = higher cost.

Patrick

GdB, you quoted it so I'm surprised you missed it but your remark of jerkiness because you let go of the accelerator and then press down again is not what I get out of the article. The transmission shifts into neutral when BRAKES are applied, not when you lift off of the gas pedal so unless you are cruising down the highway, lifting your foot off the gas and then applying brakes before pressing the gas again you won't have a problem (and such driving would cause "jerking" regardless of transmission technology when you suddenly press the brakes and then quickly press the gas pedal).

Patrick

I would guess they say almost 100% because the HEVs will use CVTs?

mkimagine

I wonder why they still looking for conventional transmission. Better solution is CVT.
If I will have such resources I will un dust some old ideas for CVTs.
How about George Constantinescu (same calling him the guru) inertia torque converter.
http://fluid.power.net/fpn/const/const005.html
It is much simpler solution and it perfectly much ICE characteristic. It is extremely simple CVT that do not required clutch what so ever. Totally mechanic, self controlling mechanical system
This what we need right now.

This what we need right now.

ToppaTom

I think the Ford PR screwed up the wording and meant to say;
"Neutral coast down. The clutches will disengage when the throttle is closed, reducing parasitic losses when coasting for increased fuel economy"
Many Ford OD transmissions unlock the torque converter when in OD, at closed throttle; to reduce fuel consumption, I believe.

As to the creep mode typical CVTs (such as VDT) include a torque converter with limited torque amplification to add creep, improve "drive-away" performance and increase ratio range. They also require a hydraulic punps for operation.
I am sure newer designs claim they can eliminate these and maybe some have.

Brian P

@Lad,

The power losses through a generator, rectifier, battery charge/discharge, inverter, and motor will be quite a bit more than the gear-to-gear losses in a mechanical transmission. Gear-to-gear losses will not be 15% in a good transmission - and given that wheel motors still require a reduction gear-set to make them a practical size, they are not eliminated!

@various,

I have a feeling that the clutch-disengagement explanation has something lost in translation. I know that with the VW diesels, fuel is cut off completely during deceleration, so if one is using the brakes anyway, might as well just leave the engine spinning while using no fuel (and save a little on brake wear). I'm sure they've thought about this, it just was not explained properly.

@mkimagine,

I am not aware of ANY CVT of ANY design that has frictional and parasitic losses that are as low as that of a gear-to-gear transmission. What efficiency you gain in being able to pick any engine speed, you lose in frictional/parasitic losses. There are already production vehicles with CVT transmissions (example Nissan Murano, Nissan Versa, and others) and they don't get fantastic mileage compared to the manual version.

The dual-clutch automated-manual design is a good one. Works for VW, it'll work for Ford.

mkimagine

@Brian_P
"I am not aware of ANY CVT of ANY design that has frictional and parasitic losses that are as low as that of a gear-to-gear transmission."

Did you check the link that I posted in my original response? If you did not pleas do so.

As for transmission efficiency: 15% (85% efficiency)losses are when you driving on the highway. In city driving that loses are like 40-50% (50-60% efficiency).

Brian P

I've seen that contraption before. One trouble with that one is that there is no way to control it so that the engine speed is matched to its optimum point throughout the required load range, and I don't see any way to balance vibration. I'm not buying it.

Brian P

One other thing; the "mechanical valve" that they are talking about is a mechanism that must alternately grab and release as the input shaft reverses. #1 there is inherently friction in this type of device; #2 that type of mechanism is a recipe for extremely high wear; #3 it is transmitting force in a series of pulses, which is not favorable.

Also, perhaps I should elaborate on the previous post regarding matching engine speed to its optimum. In low speed driving, it's most economical if the engine is just off idle speed. A crude mechanism like this is incapable of discriminating between actual idle speed, and transmitting power just off idle. It will require the engine speed to be raised quite a bit above idle before it starts doing anything.

If it was invented in 1924, and is as public as this, and hasn't gotten anywhere since ... it is NOT because it is being suppressed. It's because it doesn't do what needs to be done.

Stan Peterson

This is a little sister to the larger 6 speed Dual Clutch 6-speed showing up in the Fusion and larger cars. Think of it as just extending the transmission family.

The dry clutch design is a way of minimizing weight for these smaller platforms, and engines. It is taking advantage of the limited torque and KW that they can generate.

The real improvement is the 6 speed transmission itself that makes it possible to downsize the engine in the first place, and still provide acceptable acceleration and performance. The other supposed benefits are probably true, but of marginal utility. It seems that Ford has acquired a PR firm, that has hired a creative Engineer who knows of what he writes, to manufacture some exaggerated, but believable and good PR, for a change.


RaymondC

What this article forgot to mention that the first application of the dry-clutch Powershift DCT is the 2011 Ford Fiesta, the North American version of the new Fiesta that went on sale last fall in Europe to great acclaim.

Because Powershift has six gear ratios, it means the engine can run at lower revs at freeway speeds; this could mean we may see around 40 mpg highway rating with the EPA 2008 test, a major achievement by any standard.

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