Conclusive proof gearboxes are awesome.
- Thread starter Teh Stork
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Ken Taylor
100 W
You can challenge the patent validity on the basis that it wasn't new or is an obvious derivation. I provided some evidence once to a company challenging a patent on the basis something I'd made available on the internet was prior art that invalidated the patent http://www.google.com/patents/US6732191 .Miles said:
Ken Taylor said:
So it doesn't look novel enough to be a reliable patent then.Miles said:
I was looking where to place an SRAM order but came up with "The major probkem for me was it's huge width, enabling only a single gear sprocket with built in freewheel. It's clearly intended to be used moped fashion, one very low rider gear to pedal off the mark and then the motor automatically doing everything after that with it's two gears, the rider unable to keep up with the one very low gear. Shopper and utility market only I think, so we still await a more practical implementation." from http://www.pedelecs.co.uk/forum/electric-bicycles/12547-eurobike-2012-a.html# which had me agreeing.Miles said:
Maybe Justin's then, if it becomes available. Surely an opportunity for Bafang et. al. here?
Ken Taylor
100 W
spinningmagnets said:
Fair point but if it's as simple as reversing the motor rotation to change gear it shouldn't cost much more than the existing, quite complex, planetary hubs.
shock
1 kW
Gearboxes on electric motors is only good if you have a smaller motor for the job, hence the geared hubbies. Direct drive is the pure beauty of EV's, when it's done right. Lacking a transmission is a positive thing, less moving parts has a number of advantages. Even if you want to do some serious rock crawling or something extremely slow and excessive incline, a direct drive motor can be wound for the task.
Most of the arguments about direct drive inefficiency in this thread assumes the motor is used with a simple "all or nothing" type controller. Of course it's going to be stupidly inefficient if you just dump full throttle off the line on an overloaded motor. Now if you bring on the current proportionality to the speed then it's going to stay in the efficiency zone, which can be done simply by an inclined throttle operator, or high end controllers.
As another person who has driven a Tesla roadster sport, it's hard to explain how fast this car really is. It's hard to figure out how fast you're actually going because of how quiet it is and how there is no "pause" from gear shifts.
So in conclusion, yes gearboxes are awesome, but direct drive is spectacular.
Most of the arguments about direct drive inefficiency in this thread assumes the motor is used with a simple "all or nothing" type controller. Of course it's going to be stupidly inefficient if you just dump full throttle off the line on an overloaded motor. Now if you bring on the current proportionality to the speed then it's going to stay in the efficiency zone, which can be done simply by an inclined throttle operator, or high end controllers.
As another person who has driven a Tesla roadster sport, it's hard to explain how fast this car really is. It's hard to figure out how fast you're actually going because of how quiet it is and how there is no "pause" from gear shifts.
So in conclusion, yes gearboxes are awesome, but direct drive is spectacular.
Ken, If you can provide examples to refute what is specifically claimed in a patent, you can challenge that patent.Ken Taylor said:
There are a lot of patents on different configurations and aspects of this system of gear change.
John in CR
100 TW
Miles said:Most of the arguments in this thread show an obsession with acceleration from stop.shock said:
I don't know about obsession, since I fairly rarely launch at max potential, but it's the acceleration that can make an ebike like a great amusement park ride. No wait, no lines, no screaming crying spoiled kids, and almost no cost. There's also a huge safety aspect. ie I don't like being in certain positions relative to other vehicles on the road, so I don't allow it and move very quickly to a safer position using great acceleration.
Don't you like amusement park rides Miles?
liveforphysics
100 TW
Miles said:
Omg. I
Miles. Thank you for sharing this alternative view point related to the efficiency of something normal drive cycle EV's spend under 20% of the battery energy doing, where the 80% left goes into pushing air out of the way over some relatively close window speed range, say 1500rpm to 6500 as a random window for a motor. It's only about a 5:1 speed range where you dump ~80% of the energy in your pack gets spent operating in. 5:1 speed range is decently do-able to optimize an efficiency for that motor to stay optimized within a few percent efficiency and all over 90%. So even if you add a gearbox and it lets the motor run at a theoretical 100% efficiency, the loss of most wet sumped gearboxs (at least if it scales up to the honda B and K series gearboxes I have experience with) alone would still make it less efficient.
At least that's my $0.02 on the concept, but Im not an expert on these things.
liveforphysics
100 TW
h0tr0d said:
I don't know it. I'm not kidding when I say I'm not an expert. I think the website spec sheets for them may specify width and belt type though and you could visit the mfg's website for the belts and look it up I bet.
mdd0127
100 kW
- Joined
- Sep 30, 2008
- Messages
- 1,084
h0tr0d said:
I tried to attach the polychain design manual.
View attachment Poly_Chain_GT_Carbon_Design_Manual.pdf
Leave Luke alone. He has a controller to test
h0tr0d
1 kW
- Joined
- Apr 28, 2012
- Messages
- 460
mdd0127 said:I tried to attach the polychain design manual.
Leave Luke alone. He has a controller to test
Wrong PDF, poly GT carbon is this one:https://www.gates.com/catalogs/file_display.cfm?file=Poly_Chain_GT_Carbon_Design_Manual.pdf&thisPath=gates%5Ccatalogs&requesting=ptcatalog
Go Luke Go!
I'm pretty sure that Luke will find some flaw in that controller, not meaning it's not good quality...
liveforphysics
100 TW
h0tr0d said:mdd0127 said:I tried to attach the polychain design manual.
Leave Luke alone. He has a controller to test
Wrong PDF, poly GT carbon is this one:https://www.gates.com/catalogs/file_display.cfm?file=Poly_Chain_GT_Carbon_Design_Manual.pdf&thisPath=gates%5Ccatalogs&requesting=ptcatalog
Go Luke Go!
I'm pretty sure that Luke will find some flaw in that controller, not meaning it's not good quality...
I appreciate the kind words. I've been not opening that thr5 for at least 2 weeks now. Lol I was curious to see how many people who normally act chill flip out over it after I do it and make a nice test report. Ive been enjoying life and working at an easier pace, and even just rented a new house out of the blue that has a pool in the backyard.
Its a super narrow long-ish lap pool, which is perfect for me and its built into the deck which over looks this beautiful secluded forest. I am so freaking pumped!! Im going to get to it when I get to it. Its not a priority in my life right now to the extent that enjoying life again is.
I'm pretty well persuaded that single-ratio gearing is a good solution.
However, I think there is something missing from this statement:
All I can find on the model S transmission with a quick websearch says it uses a transaxle. I'm guessing this is a fairly traditional design with helical gears and oil. So the real question is: what's the differenc between this transmission and a multi-ratio version of it? To my mind there is no inherent extra inefficiency, just extra weight, cost and complexity.
A quick websearch suggests helical gears are typically 98-99% efficient (upto 10:1 ratio). With two lots of that (reduction and diff), bearing and oil drag, I can believe a traditional car transmission could well be around 95% efficient.
Allegedly, a large chunk of transmission loss when measured on a chassis dyno is due to the tyres (the effect of changing tyre pressures on other identical runs is supposed to be very noticable). Tranismission losses are invariably over-estimated in order to artifically inflate the engine power estimate and please the customer. I've seen people proudly showing power plots with 35% transmission losses on a FWD car!
Before I get jumped on, I'd like to point out this efficiency stuff is equally applicable to single and multi-ratio transmissions
However, I think there is something missing from this statement:
liveforphysics said:
All I can find on the model S transmission with a quick websearch says it uses a transaxle. I'm guessing this is a fairly traditional design with helical gears and oil. So the real question is: what's the differenc between this transmission and a multi-ratio version of it? To my mind there is no inherent extra inefficiency, just extra weight, cost and complexity.
A quick websearch suggests helical gears are typically 98-99% efficient (upto 10:1 ratio). With two lots of that (reduction and diff), bearing and oil drag, I can believe a traditional car transmission could well be around 95% efficient.
Allegedly, a large chunk of transmission loss when measured on a chassis dyno is due to the tyres (the effect of changing tyre pressures on other identical runs is supposed to be very noticable). Tranismission losses are invariably over-estimated in order to artifically inflate the engine power estimate and please the customer. I've seen people proudly showing power plots with 35% transmission losses on a FWD car!
Before I get jumped on, I'd like to point out this efficiency stuff is equally applicable to single and multi-ratio transmissions
kenkad
100 W
The Chorus Motor appears to be suited to a unique type of winding scheme that can be employed for dual rotor axial flux motor designs. Two things I am curious about. First, what is the level of cogging for different spans/harmonic drives and how is this comparable to having six distinct three=phase drives incorporated in the motor design. It should be a very interesting crosspoint switch to manage the spanning. There is some FEMM work going on in Europe that may shed some interesting light on these different approaches. I am hoping to see a paper on this by summer time. Clearly these approaches could significantly reduce the need for gearboxes, especially on single passenger urban commuting vehicles.
Kenkad
Kenkad
Hillhater
100 TW
just to confirm that some of the EV drag racers still believe a gearbox ( or two) is needed for serious competition ..
AussieJester
1 TW
^^^ OMG the inefficiency its making me cry...
Does two gearboxes mean double the mashing of gears!!!
ThuDSTeR i want another gearbox please, one seemingly
is not enough!!!
KiM
Does two gearboxes mean double the mashing of gears!!!
ThuDSTeR i want another gearbox please, one seemingly
is not enough!!!
KiM
liveforphysics
100 TW
If you can't figure out how to find/make a motor give you the torque you want over the speed range you want, adding a transmission can help crutch a motor for an application.
If I'm not mistaken, most of the drag racing series stuff comes from > 40year old elevator motor tech. It doesn't surprise me that its not perfectly suited for the application of drag racing. I bet in the elevator it was designed for that it just made the torque the application required over the speed range needed though.
If I'm not mistaken, most of the drag racing series stuff comes from > 40year old elevator motor tech. It doesn't surprise me that its not perfectly suited for the application of drag racing. I bet in the elevator it was designed for that it just made the torque the application required over the speed range needed though.
Hillhater
100 TW
liveforphysics said:If you can't figure out how to find/make a motor give you the torque you want over the speed range you want, adding a transmission can help crutch a motor for an application.
Yes, from what i can tell the EV racers are desperate to find a suitable motor ( weight wise), that can produce enough torque( 4000+ lbft) over a wide enough rev range such that they are still pulling hard at the end of the strip.
AJ,.. there are actually THREE "gearbox's" there..
A reverser unit ( needed for the regs), and 2 overdrive units all electronically controlled and shifted by gas pressure.
You may also be happy to hear it is powered by 90s of RC lipo.
Here is the build thread.
http://www.diyelectriccar.com/forums/showthread.php/assault-n-battery-build-thread-74539p7.html
Yeah the motors for large vehicles are kinda sad really. Some of them are designed to spin to a few thousand RPMs, tops. What kind of crap is that? these babies should spin to 6,000rpm, at a bare minimum.
I believe there just isn't enough volume for proper ones to be produced. Electric cars motors haven't seen the mass production that hub motors have, or RC motors, etc. The demand isn't there, so the comment about elevator motors etc might be spot on. I know that some of the more common EV motors were re purposed from other applications - especially where weight doesn't matter.
I believe there just isn't enough volume for proper ones to be produced. Electric cars motors haven't seen the mass production that hub motors have, or RC motors, etc. The demand isn't there, so the comment about elevator motors etc might be spot on. I know that some of the more common EV motors were re purposed from other applications - especially where weight doesn't matter.
