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Clutchless Multi-Speed Gearbox Makes EVs More Efficient

 
14 1,423 views August 12, 2010

Zeroshift clutchless multi-speed gearbox

Zeroshift clutchless multi-speed gearbox

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Currently, none of the conventional transmission designs provide an ideal option for electric vehicles. Conventional manual transmissions interrupt the drive to the wheels during gear shifting and require a clutch, adding cost and bulk to the tightly packaged powertrain of an EV. Conventional automatic transmissions, meanwhile, add bulk and also introduce a significant efficiency loss.

British transmission specialist Zeroshift has now devised a multi-speed gearbox for EVs that needs no clutch--a damper inside the gear hubs and electronic control of the motor make ratio changes seamless. Having more than one gear ratio and the ability to shift without interrupting torque means the motor runs at higher efficiency, extending battery life and driving range by as much as 10 percent.

Additionally, the clutchless multi-speed gearbox also prevents any torque interruptions during gear changes, an issue that’s so far deterred EV manufacturers from fitting multi-speed gearboxes. Current EVs instead use a single-speed transmission, but the motor then spends more of its time outside of its optimum efficiency range.

The design essentially replaces the synchromesh in a conventional manual gearbox with paired interlocking rings that change gears without interrupting the torque. To provide the required levels of shift refinement, Zeroshift’s concept uses electronic control of the electric motor or motors to match the shaft speeds and an integrated passive damper system within the drive hub to isolate any vibrations.

Zeroshift is currently developing its innovative transmission with several major automakers.

[Zeroshift]





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Comments (14)

  1. By ev enthusiast Posted: 8/12/2010 7:23am PDT

    interesting - i didnt realize that an electric motor had an optimum efficiency range. i think of them as either being on or off.
     
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  2. By cdspeed Posted: 8/12/2010 9:58am PDT

    Now I'd just like to know who the major manufactures are that have gotten involved with Zeroshift are? And wouldn't an EV with a multi-speed gearbox as opposed to a single speed be able to achieve higher top speeds which would also aid the development of racing EVs?
     
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  3. By  elji Posted: 8/12/2010 10:32am PDT

    The top speed would not change much, but the car would be much more efficient at speed, this is what matter. Electric motors are known for their high efficiency, but it's far from constant, above 6000 RPM, it can drop below 50%.
    It's not so different from an ICE, if someone could make an electric car going 100-mph with the motor at 2000 RPM, it would be fantastically efficient, and get a much longer range.
     
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  4. By cdspeed Posted: 8/12/2010 3:43pm PDT

    Thanks elji, the article didn't cover any possible performance changes. Still I do actually get excited by news like this, new technologies that will aid in bringing EVs even closer to being mainstream.
     
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  5. By ev enthusiast Posted: 8/12/2010 4:32pm PDT

    thanks from me as well. i checked, and the efficiency is not constant.
    there are so many improvements to come - most we probably havent even thought about.
    it was only recently that i found out about the motors being placed within the wheel. one day that will be standard.
     
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  6. By cdspeed Posted: 8/12/2010 8:50pm PDT

    @ ev enthusiast, You're talking about wheel hub motors, I don't really like the idea, you'd think an electric motor would be more susceptible to damage. As you drive over bumps and railroad tracks your wheels really take a beating, with motors in the wheel they would not have the advantage of being cushioned by the suspension.
     
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  7. By ev enthusiast Posted: 8/12/2010 10:05pm PDT

    have you taken a look at the actual specifications ? they look pretty solid to me.
    i like the idea for a few reasons.
    1) it is more efficient, since there is no powertrain any more. the electricity goes right to the motor that turns the wheel.
    2) each wheel has its own motor, so if something goes wrong with a motor, it is not your only motor.
    3) less room is needed, so the cars can be made smaller. or another way to put it, is that for whatever size car you have, more space can be devoted to something other than the motor, be it more trunk space, more interior room, etc.
     
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  8. By Essiemme Posted: 8/13/2010 2:08am PDT

    ev enthusiast... you know the effect of only one wheel pulling, don't ya ? The car will pull to the side of the pulling wheel... so the fact of having redundancy, may have security issues related with.
    (Essiemme) - Portugal / Europe
     
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  9. By alec Posted: 8/13/2010 2:40am PDT

    @Essiemme:yes,but if you have 4 motors,each on one wheel,the computer can turn off front or rear so as to get only front or real wheel drive,without pulling to on or the oter side
    @EV:just imagine the quality of traction control with one motor on each wheel!It's impossible not to get enthusiastic at this ideea!I think this is the future!As for the extra space,I would preffer a larger battery pack!As prices have shown a 12-15% decrease for battery packs/year,I can easily imagine a 250 mile range Leaf in 3-4 years!And if you'll be able to charge it in 20 min by then,adios gas engines!
     
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  10. By Essiemme Posted: 8/13/2010 4:41am PDT

    Sounds good... I wish the Lead could let its batteries get upgraded, as years go by...
    I wish this because I'm in the list for a brand new one... yuuuuuppppiiiii !
    (Essiemme) - Portugal / Europe
     
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  11. By alec Posted: 8/13/2010 6:00am PDT

    @Essiemme.No one will be able to stop you upgrade your battery pack.In 2-3 years there will be many battery suppliers that will offer upgrades for the LEAF in terms of more KWh/battery pack.You should easily able to expand your range to 250 KM.Or maybe even 300 km,taking into consideration Portugal's mild climate(as in No Winter :) )
    Hey,if you live in Portugal you should get some Photovoltaic panels on your house.With all that sun it should be a shame not 2.That way you'll charge your Leaf for free.Good luck Portugal! :)
     
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  12. By ev enthusiast Posted: 8/13/2010 7:32am PDT

    i wouldnt count on 250 miles in 3-4 years. it is not about whether we can do it, or whether we will have the technology.
    it is about whether the bigwigs need to have it, in order to sell us the cars of the current year.
    they want us to buy as many times as possible, so the increase in range will occur as gradually as possible. whatever is needed to get the next group of transferees from gas to electric.
    these first few years, demand will be way higher than supply.
    once the manufacturers have been able to revamp their business model, and have started putting out multiple models of evs, etc., the range may start increasing more rapidly, cuz they will have more and more cars to sell, and at some point, not as many people transferring, cuz they will have already transferred.
    i suspect 10 years from now we will be up to about 250 miles per charge.
    i think the speed of charging will be more important to people than the range of charge.
    not that many people travel that distance in between charges. but knowing that you can charge your car in 10-20 minutes, as opposed to overnight, will bring some calm to people, such that they know they are never in a position of possibly not having their car to use for hours at a time.
     
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  13. By alec Posted: 8/13/2010 1:34pm PDT

    @EV.You're probably right but I'm an optimist at heart.Actually,20 years wouldn't be such a bad wait for the funerals of the ICE.It's just that we are harming more and more our planet,and I wish it would stop,for the future of our children,if not for us.
     
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  14. By ev enthusiast Posted: 8/13/2010 4:37pm PDT

    hi alec,
    i think evs will take over way before 20 years. i just dont think it is gonna take cars that can go 500 miles on a charge, in order to take over.
    the cars coming out right now would suffice for most people.
    i have stated this before, but what we really need is a charging infrastructure for our trucking industry, that would also serve vacationers, or those taking long trips for whatever reason.
    we would then have cars solved for most everyone. and then of course as battery range increases, it would add convenience.
    i dont think there will be any new gas car sales to speak of, 10 years from now.
    my guess - 10 years from now - no new gas car sales, evs that get 250 miles per charge, and people who are still hanging onto their gas cars, because it still meets their needs, and has almost no resale value.
     
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