Hot-rodding the Toyota MGR

[e*clipse]

So here is what I've been working on.

This is the double gearbox/motor drive with some covers removed, etc.
It will use the existing gears, bearings, etc from two MGR's.
The existing ring gear will bolt to new output shafts that directly bolt to type IV VW CV joints.
Also, there is a twin gearotor oil pump in the center bearing section that integrates the output shafts as part of the pump.
The existing power connections have been swapped to radlock parts to provide a reliable and obtainable power connections. The existing resolver and temperature sensor plugs were used.

I've got drawings out to a friend w/ a CNC shop. Depending on feedback, I'm going to further scallop parts to reduce weight, etc. Also, the oiling system needs more work. It's getting closer to reality.



- E*clipse

[freebeard]

That's awesome. So there is no direct connection between the two drives and their respective CV joint?

[e*clipse]

Originally Posted by freebeard

That's awesome. So there is no direct connection between the two drives and their respective CV joint?

Right. That's part of the point of this project. I started by looking into making a spool for the differentials. The problem is making custom spools and adapters ( custom driveshafts, splines, etc ) was about the same cost as this. It was also a compromise, because the double drive system using spools on seperate MGR's is much wider and asymmetrical. Also the lubrication/cooling system issues wouldn't be addressed. Yes, an external cooler could help, but not completely solve the cooling problem. This setup allows the system to be mounted forward or backward with just a small adjustment in the pump mechanism.

The motors will be driven with torque controlled FOC, so when the motors' output torque is balanced, the effect would be the same as an open differential. However, it doesn't have to be balanced - the torque can be whatever is best at that moment. The serious advantage of this system is - well look at that Mercedes with torque vectoring.

- E*clipse

[freebeard]

It makes that four-motor 4WD concept seem much more achievable.

[P-hack]

Originally Posted by e*clipse

So here is what I've been working on.

Ah, gearing is nice, didn't know it was that sort of budget

fyi, saw this vid and thought I'd put it here. The 123kw mg2 on the highlander looks pretty much the same as the 47kw mg2 in the prius (or the mgr).

https://www.youtube.com/watch?v=u1n_W7wGn1U

but the additional planetary set allows it to spin to 14000 rpm. Which requires high voltage (or lower voltage requirements/higher amps). Napkin guess says triple the turns in hand, third the number of turns, and throw 220v @ 600A at the mgr and see if just one mgr makes 125kw (or sort out 650v@200a) and increase the gear ratio accordingly (or put go-kart wheels on it), and wonder why they didn't add the extra rpm drop to the mgr.

of course if mg1 is putting out more like 800v then adjustments will be necessary.

If you can approach your power goals with half the motor weight, that would be good. What is different about the highlander mg2 vs the mgr besides gearing?

anyway, I'm eyeing some toyota parts for the bike.

[e*clipse]

In general, yes, the motors are very similar. The resolver feedback is identical. I'm banking on this for my future stuff. I think the smaller motors in the Prius transmissions would make excellent bike motors.

I'm looking at this whole concept as a prototype. As a first stab at things, the MGR is nice because the gearing is simple.

However, the Prius drivetrain is a lot more promising for a couple reasons: More of them out there, and more power.

Something that looks really good about the Prius "transmission" is the planetary gears. If there's a way to selectively lock the planetary, it might allow a robust 2 speed drive. This is sort of how the first automatic transmissions worked.

I don't know about the Highlander MG2 vs the MGR; I really don't want to hazard a guess without having one.

One thing the MGR offers is the possibility of experimenting with independant AWD, like the previously mentioned Mercedes. Yes, one or two bigger motors would be more straight forward; this was done years ago in a Subaru WRX with twin Siemans motors.

The available gearing is actually more than a side note. Seriously, look at the cost of drivetrain stuff in $$$ or weight. The standard stuff I removed from my car was really heavy (more than 2 MGR's) and the cost of a similar gearbox (example the Borg-Warner single speed gearbox) costs more than several MGR's. I know, it's not fair to compare scrapyard parts. However, the availability of extremely well made gearbox parts rather than custom made gears makes this whole thing possible.

- E*clipse

[freebeard]

I'm thinking the part in question is technically MGR3. But now I'm wondering if anyone has chopped down the transaxle casting to hold the two MGRs and bolt up to a clutch housing. For instance replace the Prius gas engine with a VW transaxle.

In case anyone hasn't seen it, here's the [very self-congratulatory] video for Titan America manufacturing the transaxle for the Arcimoto SRK.

https://www.youtube.com/watch?v=SpGYbtd65VM

This is twin motors into a 'black box' with half-shaft outputs. I will be meeting with the Arcimoto folks, maybe later this week.

[P-hack]

Originally Posted by e*clipse

I think the smaller motors in the Prius transmissions would make excellent bike motors.

with mg1, etc, it is a bit wide. Even the mgr is a bit wide, and I would need a radial load bearing on the output, or a very solid through axle, or something.

Though I am very interested in what a realistic cnc job (pre-designed) case would cost, for say side by side mg2 stators/rotors. Or something to hold an mg2 up to the rest of my gs gearbox, somehow, even though I might never take it out of first (or just use some of the gears therein as you suggest).

Also, is there a story on cooling the mgr? That might be a major difference between this and 123kw. freebeard said something about korea?!?

re two speed, the input shaft as output occurred to me too, you can use a little bit of power to hold mg1 steady and mg2 will be reduced by .72, which is probably a useful step in an EV, or drive mg1 and mg2 together for full speed. It probably isn't worth it, I'd just weld the planetary with mg1 and 2 in phase and power them as a parallel unit if possible, and take advantage of the downstream gear reductions.

Originally Posted by e*clipse

The standard stuff I removed from my car was really heavy (more than 2 MGR's) and the cost of a similar gearbox

I hear ya, I'm looking at a gl1800 box right now and wondering what I was thinking. It's junkyard style, but there are high performance bits (and vehicles) out there that are already put together if you don't need a hobby and have the cash. The challenge really is to leverage the surplus bits.

Originally Posted by freebeard

For instance replace the Prius gas engine with a VW transaxle.

meh, I'd rather overpower/gear it enough to not need a transmission. besides the vw trans is crappy, ever get one stuck in reverse and 3rd?

Originally Posted by freebeard

In case anyone hasn't seen it

nice machine, would love to understand the costs. But wow is he pumped over a golf cart outsourcing machining has been miss-or-miss for me so far, I'm gonna start dremelling my own splines soon at this rate .

[freebeard]

I suspect he's pumped over steroids. The talk-like-I'm-deaf is just a side effect. Base price (subject to change) is $11.900. Heater and defroster are standard but doors are extra.

I think I might have gotten a VW stuck between gears ... back in the 70s, it's been a while.

The MGR3 came with a trailer towing option that was applied across the board in Korea. The Toyo/Lexus oil pump costs about as much as the MGR itself. I think it would be helpful to know how it is plumbed.

[TT-Man]

Hi e*clipse, thanks for the info posted on the Toyota MGR.
I also several years ago bought an MGR unit, thinking all the same thoughts.
I wanted to convert a small car to a local runabout.
Then started discovering the limitations.
EV's need continuous power ratings.
I thought Toyota MGs would be conservatively rated ..... seemingly not.
The 50kW rating on the MGR seems to be 18 seconds.
Logical for acceleration 0 to 60 mph so to speak.

A continuous or RMS value may not even be half at 25 kW. That might have been OK, until you find that the power available .... apparently .... is not a linear relationship to voltage. Seemingly, the motor is a combination permanent magnet and reluctance motor, all designed about the 650v applied.

I have wondered about rewinding or cutting the windings mid-point to parallel, messy.
And splitting the star point to make a delta conversion will not work.

However, I have an alternative, split the star point. bring out the 3 connections, then run a second switching inverter to effectively parallel the 2 active windings. This inveror at the star point would be slave to the main inverter.

The perceived benefit would then allow the battery voltage to be a more accepable 325 volts maintaining the original performance of the MGR.

So 18 seconds acceleration with High low end torque, and for me 25 kW continuous running power.

I may draw up my proposition and post.

The hard bit making a master and slave invertor!!

Cheers,
TT-Man