Alternative clutch technologies?

[quawa99]

Is there any clutch technology which is a good alternative to the present ones used in cars for transmission. I mean clutches which do not rely on frictional force between the flywheel and clutch plate to deliver the engine power to the wheels.

 

[etudiant]

Electric drive seems the simplest alternative.
Removes all the transmission, clutch, driveshaft and differential paraphernalia.
Admittedly, the generator, controls and electric motors and sensors needed will eat up a chunk of the savings.

 

[quawa99]

I wanted an alternative for the ones which use an engine.

 

[etudiant]

There are clutch mechanisms that use specialized magnetic fluids that turn solid or liquid depending on the applied field. The durability and cost effectiveness of that approach for consumer use is questionable at present.

In trying to get rid of the friction clutch, what are you trying to achieve?

 

[quawa99]

I am searching for a more efficient way of transmission in internal combustion engine cars.

 

[SteamKing]

The manual gearbox and friction clutch was already a pretty efficient transmission. It was inconvenient for some people to use because of the skill needed to operate the clutch. With the newer 8-speed automatic transmissions starting to appear, these configurations are starting to rival manual transmissions in fuel economy, but are much easier to use.

 

[xxChrisxx]

ZF have a 9 speed auto now. Its getting mad.


A dry friction clutch is just about the best thing you can have. You can't really get more efficient, when it has the full clamp load its effectively a rigid connection.

 

[Baluncore]

There should be no slip in a dry friction clutch unless you need it and depress the clutch pedal.
How can there possibly be a more efficient solution?

 

[SteamKing]

ZF have a 9 speed auto now. Its getting mad.


A dry friction clutch is just about the best thing you can have. You can't really get more efficient, when it has the full clamp load its effectively a rigid connection.

The ZF 8HP unit has 8 forward speeds + 1 reverse.

http://www.zf.com/media/media/img_1/corporate/products/innovation/8hp/www_11_023884zfge_8HP_Produkt_EN.pdf

 

[xxChrisxx]

ZF 9HP in the new Range Rover Evoke and the Jeep Cherokee.

Should be on sale this model year.

 

[quawa99]

I get that there isn't any other clutch technology out there which can be used in cars.Can anyone give ideas for new clutch technologies?

 

[SteamKing]

ZF 9HP in the new Range Rover Evoke and the Jeep Cherokee.

Should be on sale this model year.

The 9HP is designed by ZF, but won't be produced by them. This suggests why they don't mention it on the ZF website.

http://en.wikipedia.org/wiki/ZF_9HP_transmission

 

[SteamKing]

I get that there isn't any other clutch technology out there which can be used in cars.Can anyone give ideas for new clutch technologies?

I don't see how. A direct mechanical connection would be 100% efficient. A friction clutch approaches this figure. Different prime movers may not need to use clutches. Electric motors have high starting torque, so they don't require a transmission to multiply their output torque to a sufficient level to start a vehicle rolling while simultaneously preventing the engine (or motor) from stalling.

 

[russ_watters]

I get that there isn't any other clutch technology out there which can be used in cars.Can anyone give ideas for new clutch technologies?

Sounds like you are asking for us to invent something for you right now. Do you really think that is a reasonable request?

 

[cjl]

There should be no slip in a dry friction clutch unless you need it and depress the clutch pedal.
How can there possibly be a more efficient solution?

In fact, the reason why modern autos have (finally) surpassed manuals in efficiency is a combination of the fact that they have more ratios (including frequently a higher overdrive in the final gear), and the addition of a clutch to the torque converter so that at high speeds, they do not slip at all (older autos with just a torque converter will have some slip at all speeds, which reduces efficiency). Clutches are a great solution when efficiency is important, since as you said, they have no slip during operation.

 

[rcgldr]

Some "automatic" transmissions use a computer controlled dry clutch, usually two of them, one for odd number gears, one for even number gears, called a dual clutch transmission (DCT).

 

[cjl]

Some "automatic" transmissions use a computer controlled dry clutch, usually two of them, one for odd number gears, one for even number gears, called a dual clutch transmission (DCT).

Yes, but those tend to be larger, heavier, and more expensive than the equivalent planetary gear auto with a torque converter, and are rarely used except when shifting speed is more important than cost or size (and frequently, they use wet clutches rather than dry ones).

 

[xxChrisxx]

Eh. DCTs are lighter than autos and are of similar physical size. Mainly becauee as you don't have the slushy torque converters that are full of oil.

DCTs can't handle lots of torque though, dry clutches are limited to 250 - 300 Nm ish. Wet clutches can handle more, but can suffer in terms of handover and efficiency, due to the higher clamp loads. Still nowhere near a torque converter though.

They are also cheaper than autos because they are actually require less complicated hydraulics. So much so that they are becoming common even in small cars, displacing auto boxes.

 

[rcgldr]

Some "automatic" transmissions use a computer controlled dry clutch, usually two of them, one for odd number gears, one for even number gears, called a dual clutch transmission (DCT).

That should have been "manual type clutch" (wet or dry) as opposed to "dry clutch". Wiki article:

http://en.wikipedia.org/wiki/Dual_clutch_transmission

 

[cjl]

Eh. DCTs are lighter than autos and are of similar physical size. Mainly becauee as you don't have the slushy torque converters that are full of oil.

DCTs can't handle lots of torque though, dry clutches are limited to 250 - 300 Nm ish. Wet clutches can handle more, but can suffer in terms of handover and efficiency, due to the higher clamp loads. Still nowhere near a torque converter though.

They are also cheaper than autos because they are actually require less complicated hydraulics. So much so that they are becoming common even in small cars, displacing auto boxes.

I'm pretty sure that I read somewhere that they were both larger and heavier than a traditional auto for the same torque handling and number of gears. I'll have to look for a reference to confirm (or debunk) that and get back to you though...