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Automotive Replacing a centrifugal clutch with an Electromagnetic clutch

  1. May 25, 2017 #1
    Hello friends,

    Anyone ever thought of, or tried, or has come across an automobile with an EM clutch, probably electronically controlled? We have a CVT driven 2 wheeler with a centrifugal clutch, but we need to disconnect power at will (electronically), so an EM clutch was suggested. Anyone know how it can be done, and if there are any suppliers of EM clutches, preferably for automobiles?
    We roughly have an idea of when the centrifugal clutch engages and drive is transmitted (a little less than 1000 rpm, but that can be calculated, not a problem). Our situation currently is that
    1- we aren't sure on how to do it, as it might require complete redesign and manufacturing of the output shaft. We know how much space is taken up by the centrifugal clutch, and the space between that and the secondary pulley of the CVT, but since we don't know of any EM clutches of any suppliers, we aren't able to carry forward with any designs.
    2- A Centrifugal clutch engages, more or less, gradually, so as to avoid jerk in transmission. We need to replicate that as much as possible, probably by varying the current supplied over a range to allow for engaging as the field reaches maximum engaging field. Anybody has any idea?

    Awaiting a positive reply,
    Thank you
     
  2. jcsd
  3. May 25, 2017 #2
    Don't the current dual-clutch transmissions found mostly in high-end sports cars use electronically controlled clutches? They must have some kind of gradual takeup to allow taking off from a standing start. You didn't say what your power-handling requirements were, but that might be a start.
     
  4. May 25, 2017 #3
    Have you talked to your current supplier about prototyping an electronically actuated version of the current-production centripetal clutch? To me, that would be the easiest way to integrate this technology into a pre-existing system. You could keep what you know to work well, and add what you want.

    How much torque do you need to transmit? What sort of life expectancy and duty cycle? There are a number of options that could possibly work, or be learned from.
     
  5. May 25, 2017 #4
    Well, it is run by a 110cc engine producing 7.88hp and 8Nm torque.
    DCTs are waaay out of our league. We need a CVT-grade, scooter need EM clutch.
     
  6. May 25, 2017 #5
    Thats the thing. All the suppliers we know, and the ones in India focus primarily on Machine tool EM clutches, and they don't do single part manufacturing or prototyping. They only undertake bulk orders, for mass production, say. So we would have to design from scratch, and neither do we have the time, nor would anybody manufacture that.
    That's why, we are looking at existing small sized clutches, even abroad that could fit, but aren't able to find any.
     
  7. May 25, 2017 #6

    Tom.G

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  8. May 26, 2017 #7

    CWatters

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    I think small ones are used to connect car air conditioning pumps to the engine belt.
     
  9. May 26, 2017 #8
    Finding an EM clutch that can handle your torque demands will not be difficult. They are common, proven, and inexpensive.

    What are your packaging constraints? Maximum diameter and maximum height of current clutch?

    As far as the engagement of the clutch is concerned, I don't know exactly what to suggest. Is there any possible alternative that can be used to mitigate the harshness caused by a more abrupt clutch engagement? Could you change the gearing for that range of RPM to provide a soft start? Retard the timing during engagement so that the power is not sudden and uncontrollable? etcetc
     
  10. May 26, 2017 #9
    Thanks.
    One thing to be noted here is that ALL those are machine tool EM clutches. You can make out by the key way in the hole- you don't get such shafts inside a CVT.
    We did come across that catalog when searching. The fact that it doesn't fit automotive applications is a reason for elimination. The other being overall space required- too wide.
     
  11. May 26, 2017 #10
    Are they? Haven't found any so far. Worth checking. Thanks for the info.
     
  12. May 26, 2017 #11
    It has been remarkably difficult, given that we have no suppliers here, and budget constraints limits us to India, as of now.
    Common? In terms of car use, maybe. IN terms of 2 wheeler use- none found so far. Proven? Definitely. Inexpensive? Really? Not sure. What would a small one of 12 inch diameter cost? Do you know any good suppliers in and around where you stay?
    Packaging constraints- the CVT. Around 1 inch. Thats all the shaft space that we have, with a max diameter of 120mm.
    If we can find one with a catalog and at a good price, we can work our way in controlling it.
     
  13. May 26, 2017 #12

    CWatters

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  14. May 27, 2017 #13
  15. May 27, 2017 #14
    Anyone know whether that centrifugal clutch can be replaced by a normal bike clutch, but electromagnetically actuated? If so, how would one do it?
     
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