Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Alternative clutch technologies?

  1. Feb 22, 2014 #1
    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.
     
  2. jcsd
  3. Feb 22, 2014 #2

    etudiant

    User Avatar
    Gold Member

    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.
     
  4. Feb 22, 2014 #3
    I wanted an alternative for the ones which use an engine.
     
  5. Feb 22, 2014 #4

    etudiant

    User Avatar
    Gold Member

    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?
     
  6. Feb 22, 2014 #5
    I am searching for a more efficient way of transmission in internal combustion engine cars.
     
  7. Feb 22, 2014 #6

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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.
     
  8. Feb 22, 2014 #7
    ZF have a 9 speed auto now. Its getting mad.


    A dry friction clutch is just about the best thing you can have. You cant really get more efficient, when it has the full clamp load its effectively a rigid connection.
     
  9. Feb 22, 2014 #8

    Baluncore

    User Avatar
    Science Advisor

    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?
     
  10. Feb 23, 2014 #9

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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 [Broken]
     
    Last edited by a moderator: May 6, 2017
  11. Feb 23, 2014 #10
    ZF 9HP in the new Range Rover Evoke and the Jeep Cherokee.

    Should be on sale this model year.
     
  12. Feb 23, 2014 #11
    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?
     
  13. Feb 23, 2014 #12

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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
     
  14. Feb 23, 2014 #13

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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.
     
  15. Feb 23, 2014 #14

    russ_watters

    User Avatar

    Staff: Mentor

    Sounds like you are asking for us to invent something for you right now. Do you really think that is a reasonable request?
     
  16. Feb 24, 2014 #15

    cjl

    User Avatar

    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.
     
  17. Feb 25, 2014 #16

    rcgldr

    User Avatar
    Homework Helper

    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).
     
  18. Feb 26, 2014 #17

    cjl

    User Avatar

    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).
     
  19. Feb 26, 2014 #18
    Eh. DCTs are lighter than autos and are of similar physical size. Mainly becauee as you dont have the slushy torque converters that are full of oil.

    DCTs cant 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.
     
    Last edited: Feb 26, 2014
  20. Feb 26, 2014 #19

    rcgldr

    User Avatar
    Homework Helper

    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
     
    Last edited: Feb 26, 2014
  21. Feb 26, 2014 #20

    cjl

    User Avatar

    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...
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Alternative clutch technologies?
  1. Alternate to clutch (Replies: 8)

  2. Dropping clutch (Replies: 3)

  3. Clutch Question (Replies: 2)

  4. Gears and Clutch (Replies: 0)

Loading...