| Author | Message | ||
     Jcjohnson33 |
http://blog.motorcycle.com/2012/04/03/design/frog- ebike-the-electric-successor-to-1985-frog-fz750-co ncept/ | ||
| Froggy |
DO WANT!  Shame it is just a concept. | ||
| Glitch |
Shame it is just a concept. I believe it'd be more than a concept if there were battery technology that could fit in the impossibly small battery compartment. | ||
| Blake |
That looks to me like one of the dumbest motorcycle designs ever. "The eBike’s electric motor is actually located in the hubless rear wheel." Can't get much dumber than putting that kind of mass onto the rear wheel assy. Interesting aesthetics are not equivalent to good design. At some point, the e-bike folks are going to realize the advantage of a multi-ratio transmission. I can't see owning a serious motorcycle without one. Double the drive ratio, double the torque at the rear wheel. Direct drive is okay for golf carts and the like, but not for highway speed vehicles. | ||
| Kenm123t |
Blake A/C Power and freqency drives can give nearly any ratio and torque curve Daikin VrV systems run 56 hz to 289hz in normal operation they use a D/C vector drive. The issue is limited battery life every conversion has waste heat. State of Florida requires a Freq drive equiped pool pumps Drives are getting cheaper and more common | ||
| Blake |
But Ken, every motor has it's maximum output. With mutiple drive ratio transmission, that maximum output can be multiplied for greater power to the rear wheel. HP=Torque*RPM/5250 whether the motor is powered by electricity or gasoline. All else being equal, if you double the RPM of the motor then you've doubled the HP to the rear wheel. A motor putting out full torque at a low RPM is putting out a low HP. There is just no getting around that. (Message edited by blake on April 04, 2012) | ||
| Reepicheep |
It's a pretty sculpture that is almost, but not quite entirely, unrelated to a motorcycle. (a tip of the hat to Hitchhikers Guide to the Galaxy) | ||
| 86129squids |
Loony-goony to me... I appreciate "concepts" as much as anyone, but that kinda pushes the "too much time on one's hands" button. Obviously they COULD produce something more practical, why not? | ||
| Jaimec |
Who needs a battery? I'm sure even a small oscillation overthruster would be more than enough to power that baby for a year or more without needing replacement. | ||
| Glitch |
Here ya go Blake. http://www.motorauthority.com/news/1059461_brammo- announces-new-iet-transmission-for-electric-motorc ycles-video | ||
| 86129squids |
"oscillation overthruster"? Shake-weight? I was trying to remember that South Park episode where someone invented a pretty vulgar/funny wheel that everyone started using... | ||
| Cityxslicker |
not so much .... This thing on the other hand.... http://blog.motorcycle.com/2011/09/14/manufacturer s/bmw/husqvarna-e-go-entry-level-electric-motorcyc le-revealed-in-frankfurt/ pure trouble for down town - if they can keep the price reasonable ! | ||
| Glitch |
And yet another "e-bike" that has to wait for battery technology to catch up. Both of those bikes haven't the room for batteries as we have them today. BMW/Husky are being too optimist with regards to bike weight as well. | ||
| Darth_villar |
Fly by wire motorcycle? Seems like a completely unnecessary complication to me... at the very least, I sincerely doubt it would be the lightest route. That said, my current city commute is only about 15-30 miles a day, and if electric bikes are ever cheap and fun enough to buy, I will have one. | ||
| Sifo |
At some point, the e-bike folks are going to realize the advantage of a multi-ratio transmission. I can't see owning a serious motorcycle without one. They make it work for e-cars. I won't say there isn't some benefit to multiple gears, but all engineering is compromise. Adding a transmission adds weight, rotating mass, complexity, maintenance, and perhaps most importantly, cost. It is also rendered less important because, unlike an internal combustion engine, an electric motor fairs much better being run at high RPMs, and tend to actually be quite efficient doing so. Basically, what works best for an IC engine doesn't necessarily carry over to an electric motor. | ||
| Jaimec |
Exactly. What a lot of people forget is that electric motors don't HAVE a "Powerband" like a gas engine. They are ALWAYS putting out peak power. The reason a transmission exists is to let the engine run at the most efficient rpm for a given road speed. Everyone here knows what it feels like when you try to exit a turn and your engine is nowhere near its "sweet spot." | ||
| Jaimec |
86129squids: You've NEVER heard of the Oscillation Overthruster?? It predated the Flux Capacitor as a power source! | ||
| Firemanjim |
Hey, Blake, seen a few with transmissions recently. Can't remember if it was at IMS show or one of the manufacturers we had at ASBN recently. Rex may remember. | ||
| Nik |
A motor putting out full torque at a low RPM is putting out a low HP. There is just no getting around that. Or you can make a motor with multiple windings, that's capable of multiple torque curves. "Shift" between the windings, and no mechanical losses. P = IV for electric. With enough current or voltage you can put out as much power as you want at any rpm. This is why the controller and pack voltage is usually the bottleneck in ev performance, not the motor. The motor is only limited by how effectively it can be cooled. | ||
| Nik |
Hey, Blake, seen a few with transmissions recently. Can't remember if it was at IMS show or one of the manufacturers we had at ASBN recently. Rex may remember. That would be Brammo. Exciting, but Vaporware. | ||
| Blake |
>>> They are ALWAYS putting out peak power. Jaime, you're mistaken on that. You're confusing peak torque with peak power. Power equals torque times velocity, in the case of a motor, its angular velocity. The myths about electric motors are funny. You can't get unlimited power from an electric motor. Electric motors are rated for both a maximum current (to prevent melting of the windings) and also a maximum torque (to prevent shearing of the output shaft. Some here seem to imagine that the motors being used on electric vehicles are some kind of magic motor. They aren't. Exceed the rated amperage; they will melt windings and fail. Exceed the rated torque, they will break the output shaft and fail. So say you have a 30 HP motor. Its power curve goes pretty much linearly from 0 HP at 0 RPM to 30 HP at maximum rated RPM. The torque can be constant across the rpm range of a motor. The power cannot. If you want more power to the back wheel, you need a mechanical advantage, a multi-ratio transmission. At low RPM you get low power. There just is no way around it. | ||
| Sifo |
So say you have a 30 HP motor. Its power curve goes pretty much linearly from 0 HP at 0 RPM to 30 HP at maximum rated RPM. The torque can be constant across the rpm range of a motor. The power cannot. If you want more power to the back wheel, you need a mechanical advantage, a multi-ratio transmission. At low RPM you get low power. There just is no way around it. But it also isn't true that the torque is constant across the RPM range. Electric motors do develop peak torque at low RPMs (also huge current draw that will burn the motor up). The torque drops with higher speeds though. This makes the HP across the RPM range much flatter than we are used to seeing with gas engines. Or you can make a motor with multiple windings, that's capable of multiple torque curves. "Shift" between the windings, and no mechanical losses. I'm pretty sure that the more windings you have the more power you get. The trade off is that you either need thinner wire, reducing the current capacity, or the armature gets much bigger and heavier. There are no free rides. | ||
| Blake |
Just think of the difference a three speed transmission would make with ratios of 3:1, 1.5:1 and 1:1 compared to a direct-drive (1:1) scheme. When in 1st gear, the bike pulls 3 times as hard. When in 2nd gear, it pulls 1.5 times as hard. When in 3rd gear, it pulls the same as the direct drive version. Well neglecting the 10% loss due to tranny efficiency. | ||
| Blake |
Sifo, The motors that lose torque at high speed are being run past their conventional design speed I think. Thus they suffer some degradation. It's not much. If it was then of what use is that speed range of the motor? Cruising only, no overtaking? Regardless of a particular motor's torque characteristics a gearbox with multiple speeds will greatly increase acceleration in the lower gears. I'm not sure why anyone wouldn't like that. I had this discussion before months ago in another thread. Someone posted a power curve for the motor versus motor speed. It started at zero and went nearly linearly to it's max, then yes in the overspeed region it went limp. Point being, the torque in the lower 70% to 80% of the motor speed range was flat. Flat torque produces a linear power curve. | ||
| Glitch |
Q. You say the bike puts down 198 horsepower is that at the wheels or the output shaft of the motor? A. It makes 194 horsepower at the output shaft of the motor, which revs up to 8,000 RPM. However, we do not have a transmission, only a jackshaft with a single, fixed gear ratio, so there is negligible power loss back to the rear wheel in our case. Interesting reading about Chip Yates and the electric superbike. http://www.chipyates.com/electric_faq | ||
| Jaimec |
Sadly, the Brammo Empulse is the "Duke Nukem" of the motorcycle world... | ||
| Glitch |
Sadly, the Brammo Empulse is the "Duke Nukem" of the motorcycle world... I would appear so. But after reading about e-bikes this afternoon it's obvious these bikes do well with direct drive. You could build it with one I suppose, it just doesn't seem to need one. MotoCzysz is in on the transmissionless conspiracy as well... | ||
| Nik |
I'm pretty sure that the more windings you have the more power you get. The trade off is that you either need thinner wire, reducing the current capacity, or the armature gets much bigger and heavier. There are no free rides. You misunderstood, or perhaps I should have stated, multiple 'sets' of windings. It's like having multiple motors in one housing. Yes more weight, but more than what a transmission would add? With less losses... There's already motors out for motorcycle ev conversions that do this. | ||
| Jaimec |
Not to forget that when "Duke Nukem: Forever" finally DID come out, it was universally greeted with a big yawn and lukewarm (if not outright hostile) reviews... | ||
| Froggy |
Except that DN Forever was a fine, just nothing special or revolutionary. If you didn't play it thinking it was going to be the best thing since sliced bread, you would enjoy countless hours of throwing poop at aliens and cheesy one liners. (If anyone has Steam and wants my extra copy, hit me up http://steamcommunity.com/id/Froggypwns ) |
