Hot-rodding the Toyota MGR

[e*clipse]

Originally Posted by Cyruscosmo

D Damn E*clips! I feels like I been schooled!

But that is a good thing, as I said I don't know electric motors the way I know ICE's.

Ok so I understand a few more things now. Why the little high revving AC motors use a lot of reduction gears like little gas turbines and why the big DC's don't. I had not thought about this until I read your post but when we started brainstorming the transmissions the only motors we had in mind were the big DC's.

My primary concern was reducing the wire sizes and amps needed to get a vehicle going in a timely manner without resorting to drastic measures like 2000amp controllers, huge cables, more batteries or stacking two 11 inch motors. Those things are not light! So the thought was a 9inch with a couple gears to help it along a bit.

I have a couple 9 inch motors here and a few boxes of C4 parts all I need is a case for those parts and I can give it a go. That will come next summer when I finish the forge and start making ingots.

So I imagine you know what the term "BLDC out-runner" is yes? I had this thought of building an 11 inch out-runner. My reasoning was to do away with the transmission all together only I was going the larger diameter low RPM more torque rout instead of the smaller diameter high RPM gear reduction rout.

What are your thoughts?

Cyruscosmo

Cyruscosmo,

This has been bugging me all day. - I felt like I got into "argument mode" and I hate that about myself.

We all have different backgrounds, talents, etc. all of which can be very helpful. Your knowledge and experience as a "gear head" is very valuable; and I truly respect your input around here. Working with Dave Cloud is excellent real-world experience and having him as a neighbor must be really fun!

I need to learn how to be more accepting of other ideas. There's a lot I can learn and hopefully folks will actually enjoy working on these projects.

So, please accept my apologies for the reply - it would be so much better to encourage folks and learn together.

Yes, I would like to help and attempt to answer your questions - I just need to sit and figure out how to encourage questions.

- e*clipse

[freebeard]

I looked it up: Brushless DC electric motor - Wikipedia, the free encyclopedia

It turns out my [850 watt] Fisher & Paykel washing machine motor is an outrunner. They're popular for homemade wind turbines. I want to put the generator at the bottom of a mast with a long thin driveshaft to the top. Low winds would wind up the shaft in torsion until some minimal gust would kick it over the initial start-up friction. It's a cogged motor, there's a little resistance at each step.

e*clipse -- Maybe it's just me, but I didn't see that at all.

[e*clipse]

It's a group dynamics thing I've noticed with a few other projects I've worked on. In a very open group, or one just starting (before politics and personalities get involved) there can be an amazing "energy" that brings out new ideas. One thing that can really hurt is a "know it all" in the group.

I really like the positive free ideas energy in this group of folks, and I'm trying to do my best to help out. I'm also not very good at this, so please have some patience with me.

Regarding outrunner motors, I'm familiar with them from an RC airplane and helicoptor perspective. One definite advantage they have is the magnets are attached to the inside of the (outside) rotor, so there's little danger of the magnets spinning off.

A thing that may be helpful with the motor/transmission decision is a general spreadsheet to calculate torque required, speed required, torque delivered to the wheel, etc. Inputs could be final drive ratio, tire diameter, gear ratio (s) , motor torque/ power curve.

For example, what final drive gear ratio does the Subaru diff use? What gear ratios are available in a C4 transmission? I'm just using these specific numbers because real numbers would be helpful. I do have all that info for my truck, but I've noticed that a tranny designed for a turbocharged gas engine isn't optimum for a turbocharged diesel engine. This really must be true for and electric motor.

[Cyruscosmo]

Hey E*clips

Umm I did not feel as though I was being "argued" with. No, on the contrary I love a good discussion with flying ideas and points of view. You have not offended me in any way and no apology is necessary or expected.

I will be the first to admit I don't know everything. I am pretty sure that if I did my brain would melt and leak out of my ears!

I have enjoyed this thread immensely as it has answered a lot of questions I have had that tend to drive Dave crazy. He knows his DC and lead acid batteries and what combination it takes to make what vehicle do what and I have learned a lot from him.

But I could not help noticing that the tendency to add larger motors and more amps was the common answer as to how one would get a car rolling faster. And auto companies seem to be going the Higher voltage more gear reduction rout.

That is why I first started thinking of a transmission for the job of torque multiplication. Electric motors have a wider usable torque range so there would not need to be as many gears so I chose the two speeds of a C4.

My ultimate goal would be an out runner that had low rpm's and torque like a diesel engine.

I value your answers E*clips that is why I keep asking questions and presenting ideas.

Cyruscosmo

[Cyruscosmo]

Originally Posted by freebeard

I looked it up: Brushless DC electric motor - Wikipedia, the free encyclopedia

It turns out my [850 watt] Fisher & Paykel washing machine motor is an outrunner. They're popular for homemade wind turbines. I want to put the generator at the bottom of a mast with a long thin driveshaft to the top. Low winds would wind up the shaft in torsion until some minimal gust would kick it over the initial start-up friction. It's a cogged motor, there's a little resistance at each step.

e*clipse -- Maybe it's just me, but I didn't see that at all.

Yes Yes... That type of bushless DC is great for the DIYer. I got hold of four of those motors from an appliance place in Monroe and am toying around with the idea of stacking all four stator core sets together and rewinding the coils. Lose the sad example of magnets they use and add a steel bell with a set of four inch long neo magnets and see what I can get out of it. The stator cores would be offset to reduce cogging.

I am collecting metal for a mast to mount a wind turbine above my shop. The mast will be triangular so I don't need any extra guide cable. The generator will be connected with a section of drive shaft and slip yoke so that I can remove and tinker with it without having to remove the turbine as well. The generator section will slip down the inside of the mast.

Am looking at using a Vertical Axis type wind turbine mounted on the wheel bearing stub of a Dana 60 rear axle. This way I have a brake in place in case I need to stop the rotor. I don't really have room for a large diameter conventional spinning blade.

Cyruscosmo

[freebeard]

I forgive everyone.

I like vertical axis windmills. Are you thinking lift or drag?

Ontopic, I got together with my buyer* and found out how soon the money runs out ($1300) and ordered the crossbar (52380F) and bushings (41654B, 41653D, 41651G) to mount the MGR. Once that crossbar is in hand I will be able to design the front mount.

Any news on the axleshafts?

*the guy has a barn-full of restored VWs and I got him to watch the Zelectric video. He noticed the $45K asking price, and has a [flakey] machinist he needs to keep busy.

[Cyruscosmo]

Originally Posted by e*clipse

It's a group dynamics thing I've noticed with a few other projects I've worked on. In a very open group, or one just starting (before politics and personalities get involved) there can be an amazing "energy" that brings out new ideas. One thing that can really hurt is a "know it all" in the group.

I really like the positive free ideas energy in this group of folks, and I'm trying to do my best to help out. I'm also not very good at this, so please have some patience with me.

Regarding outrunner motors, I'm familiar with them from an RC airplane and helicoptor perspective. One definite advantage they have is the magnets are attached to the inside of the (outside) rotor, so there's little danger of the magnets spinning off.

A thing that may be helpful with the motor/transmission decision is a general spreadsheet to calculate torque required, speed required, torque delivered to the wheel, etc. Inputs could be final drive ratio, tire diameter, gear ratio (s) , motor torque/ power curve.

For example, what final drive gear ratio does the Subaru diff use? What gear ratios are available in a C4 transmission? I'm just using these specific numbers because real numbers would be helpful. I do have all that info for my truck, but I've noticed that a tranny designed for a turbocharged gas engine isn't optimum for a turbocharged diesel engine. This really must be true for and electric motor.

Hey E*clips

Yeah I hear ya. I have followed many projects online and seen them degrade into the... "my tool is bigger than yours" mud slinging.

The way I do things is weld up an assembly and see if it goes boom. I have no real world reference for numbers so when it comes to math I am a bit lost, as a result I find physical parallels. When gathering info for an electric car project the usual answer to getting off the line faster is more amps/bigger motor/bigger controller...

I know people don't like to shift gears because of the danger of over revving the motor but as I have heard them all say "when they need a little extra for hills or jumping on the freeway they shift. So why not just add two automatic gear ranges to help when needed... Hence my thoughts of going with the C4 from the get go.

For some stock numbers start with C4 (OEM) 2.46 1st 1.46 2nd 1.00 direct and the final drive "differential" ratio would be chosen depending on the torque curve of the motor used. If the motor has gobs of torque such as a modified outrunner then a highr final drive like 3.5 would be in order. If the motor was like the MGR's then a lower final drive ratio would be used like 4.44. But there is also aftermarket gears that can range about anything you like.

Either way the end result would be as if you had no transmission when in direct drive. You would just have the added benefit of extra torque when needed without resorting to higher amps and all the pit falls that come with it.

Shifting would be a simple matter of telling the controller to pause for the clutches to switch and then resume.

Cyruscosmo

[AlexanderB]

an automatic gearbox in an EV is a good thing in pretty much every way, it just 1: needs to stand up to the torque, and 2: get rid of the wastefull torque converter.

Other than that, its great, its easy to control/automate, no need to use a clutch or change manually with the risk of overrevving, etc..

[e*clipse]

Cool - thanks for the numbers, CyrusCosmo!

I'm glad my response didn't bug you; often people don't talk about it, you just notice a lack of enthusiasm or participation. I certainly don't want to get into a "my tool is bigger" contest, especially with the tools I have...

When I first started thinking about this, the AC Propulsion motor was about the only high performance AC option. It was way out of my budget, so I spent some serious time looking into small, efficient trannies that would work. Unfortunately, everything I found was "custom" and expensive as well. The options available now - batteries, motors, trannies, etc - make this really fun!

I'll put together a spreadsheet with some form of combined output torque and speed graph. I'm really curious to see how this will work out. Oh yeah, would you have weight #'s for the C4 and a scoobie diff? It seems it would be good to compare the system performance.

[e*clipse]

FWIW, I've been spending some time staring @ the cumpooter, playing "what if" scenarios based on the MGR. Since there are no real tests ( like ORNL's ) on the MGR, I'm trying to accurately simulate the performance, based on the 2010 Prius data.

The big question in my mind is "what if you don't have 650V to power this thing?" For example, my 48 Nissan Leaf modules will put out 393V max.

I know there are some big compromises involved - there was a guy who put one of these into a Saturn and was not happy with the results. From what I know now, it was pretty much doomed to fail. Not to rip on him - he certainly forged new ground with the conversion; it's more to learn and hopefully make a better setup.
1) He used a relatively low voltage battery pack - something less than 300V.
2) He used a standard motor controller designed for BLDC motors.

I'm not sure if he had control of field weakening - since he used a good quality new controller, I'll assume he did. However, the controller did not give the ability to control reluctance torque, which can increase the output in the MGR by about 60%!

Even with field weakening and control of the reluctance torque, the numbers ORNL found for the 60kW Prius motor when using a 225V "link" voltage are pretty pathetic. The "link" voltage is basically the DC bus voltage - in our case, the battery pack voltage. Their tests ( graph on pg 66 of the 2010 Prius test ) show a maximum torque of 120 N-m (88 ft-lb) and a maximum speed of 5000 RPM. The constant torque section ends at 1000 RPM.

So, the maximum power output at 225Vlink is 88ft-lb*1000RPM/5252 = 16.75 hp. I know this doesn't make sense - you have to convert the link voltage to 3phase rms voltage, then the #'s start to work.

You can't simply increase the current to make up for this. These tests were pushing the stator windings to their limits - we're talking about 200A - and that can only be sustained for 10 seconds while using 10*C coolant! Obviously, the passively cooled MGR is going to require serious cooling improvements before getting close.

I'm getting close to something that will allow me to put in different link voltages and calculate different torque-speed values. Hopefully this will allow good motor control and help with some realistic expectations.

-e*clipse