Controller mods or build for E-assist altermotor

[freebeard]

I just bought one for $85.00 today.

Could we trouble you for a measured drawing, or an annotated photograph?

I exhumed my engine assembly and got a 8x8" can to compare. The stock generator/cooling fan shaft is 3 1/2" from centerline. The fan plate is 10" in diameter; I don't have a generator, but they must be about 6" in diameter.

The coil, fuel pump and distributor would have to go, but a crank fired MSD ignition and electric pump are an upgrade anyway, and they offer mounting opportunities for the serpentine belt system. The most likely interference would be the electrical junction box and the arc of the stock cooling fan. A Type III cooling system could be easier but would sacrifice either the stock exhaust system or bodywork. Here's a serpentine belt retrofit. It's belt and tensioner are lighter, but it shows which side the idler pulley would go on.


http://www.shoptalkforums.com/viewtopic.php?t=127562

[HaroldinCR]

Once the alternator gets to my son's house, I will have him do a sketch/measurements. I won't see this thing for a month yet.

[freebeard]

S'okay. Things move slowly here too.

Does he do technical drawing? The important things are three associated [X-Y-Z] views, the overall dimensions and the center-to-center of mounting holes in the X-Y-Xth directions. TIA

Edit: An example


https://www.google.com/search?q=3-view+drawing

[HaroldinCR]

What exactly are those measurements for ? If they are mounting bracket, the alternator has a "camel humps" type mount I believe on the bottom of the case. 2 projections for bolting to another bracket that bolts to the engine.

I don't believe you are trying to mount this as an inline direct coupled motor, correct ? You might try a jack shaft set up for e-assist ?

Once he gets it, we will get him on this thread. He may as well get involved also, right ?

[cajunfj40]

Hello again thingstodo,

Originally Posted by thingstodo

Hi

The inside wheel should have more torque, since it has more slip. Breakdown torque on an induction motor is 3.5 - 4 times rated torque ... but each motor seems to have it's own base speed. We have ACIM on all of our equipment (at work) and changing out a motor DOES change the speed that the motor runs when lightly loaded. Loaded - it's only a few rpm.

But if the inner wheel is pulling hard the outer wheel should be OK going along for the ride?

Hmm.

With an "auto-locker" (Detroit, Lock-right, etc.) in a corner, the inside wheel drives around corners when there's good traction and low throttle input. The outer wheel unlocks and freewheels faster than the ring gear, clicking past the dog clutches in the locker. Hit the gas and break traction on that inside wheel, the locker dog clutches lock and instantly slams the torque available to the outer wheel. Usually breaking traction on it, causing that end of the vehicle to slide out. On slick surfaces, this happens a lot easier - so you coast around corners.

The "higher torque available to the slower motor" issue could cause similar behavior. The inside wheel gets more torque because it is slipping more than the outside wheel (assuming both motors are loaded, so both are going slower than commanded speed), while the body rolls away from said wheel, unloading it. Once the traction drops below what is needed to keep the tire from slipping due to torque, it lets go. No max overspeed, because AC, that's nice. The whole vehicle slows down a bit since it isn't being driven by that wheel anymore. Now the outside wheel is going even slower than commanded, so slip goes up. Thus torque goes up. Traction is higher than it was on the inside (all else being equal, body roll will do this), so it takes longer to let loose, but when it does, now both wheels on that end of the car are spinning and it's sliding out. Again, this would probably happen faster on slick surfaces.

The point being, without an "open" differential, when one tire lets go the other gets the rest of the torque, making it more able to break traction. Hmm. Maybe slap pulleys on either side of a "truetrac" geared limited-slip differential, and run without a pinion or ring gear at all? I wonder if that'd allow the proper torque biasing.

My existing/planned setup is only RWD. A warp9 DC motor coupled to a 2002 Honda civic gearbox ... and obviously a DC Controller. I am planning to use it as a Side by side Quad/offroad buggy. Top end or redline (5500 motor rpm) in second gear would be in the 50 mph/80 kph range.

Going to 4 of these motors, one per wheel, driven by one AC controller and battery pack would be great for traction and control. The tires on it give about 1000 revs per mile. 1000 rpm on the wheels = 60 mph. So if I went for .. 20 mph? .. that's 333 rpm. And if I limited to 3000 motor rpm ... I could go as high as 9:1. I have read elsewhere that anything more than 3:1 would require 2 stages, which complicates things.

Belt slip may be bad. I am thinking $10 belts and single drive pulleys. I guess I am assuming that the belt tensioner would let the belts slip if you go over the rated torque? Maybe that's a bad assumption.

Sounds expensive. Maybe I should look around for a spare belt?

I think you missed my point - it's a glorified fan belt. Nothing too special. It'll cost more than a "plain" fan belt, but it should be pretty common. You still don't want it to slip. The tensioner just keeps the "slack" side of the belt from flopping around. If you want reverse and/or regen braking you will want a "set the tension by setting the distance between the pulleys" setup, else the belt will always slip on reverse and/or regen as the slack swaps sides. A really strong tensioner could work, but might need to be impractically strong to function properly, leading to too much side load on the pulleys.

Check the Gates website, there's a nice pdf in there somewhere for their toothed belt drives, including power calculations, pulley diameter ratios, etc. Higher "gear" ratios are only a problem due to the physical space they require for the larger diameter pulley.

In any case, unless you want to run leading and/or trailing arms (think motorcycle rear suspension) on both ends, you'll need CV jointed half-shafts to bring the power out to the wheels. You may be better off with one motor and the driveline out of something like a Subaru or a 4x4 ATV. Used LEAF motor? Car-part has them as low as $445. More than 4x $85, but you get to use existing driveline parts...

[freebeard]

Anything with dog clutches is not a Quaife. Quaife Limited Slip Differential I'm not prepared to explain how they work. ETVTV have them exclusively for the Tesla.

Good point about bi-directional tensioning for regen.

https://en.wikipedia.org/wiki/Gilmer_belt is good for hundreds of horsepower, mating a GMC 6-71 supercharger with a Donovan block hemi for AA-Fuel.

What exactly are those measurements for ?

A 1:1 scale model.

[cajunfj40]

Hello freebeard,

Originally Posted by freebeard

Anything with dog clutches is not a Quaife. Quaife Limited Slip Differential I'm not prepared to explain how they work. ETVTV have them exclusively for the Tesla.

Well, yes. That's why I talked about clutch-type limited slip or auto-locker. Both show the undesired characteristics in snow, though the limited slip may be more predictable because it starts "locked" and only differentiates when there's enough traction to overcome the clutch pack inside. The Quaife, Tor-Sen, TrueTrac and a few others I can't recall right now are the more desirable geared type that are "unlocked" first and bias torque once a wheel starts slipping. I'd have to read up more to see how much RPM differential/torque differential it takes to bind the gears and start the torque biasing process. The Torsen R series has clutches inside as well that provide a minimum amount of torque it can bias, even when one wheel is in the air. Not sure how they work on ice vs. a standard Torsen in terms of acting more like a clutch-type lsd or an open diff at first.

My point about the truetrac/torsen/etc geared limited slip between two motors was to see if the torque biasing it has would allow keeping the inside wheel loaded some once it lets go, by having the gearing in the truetrac bind up. Again, I need to do more reading to see how the ring gear affects the torque bias - does the diff case need to be locked to one axle for it to function properly without any ring-gear supplied torque.

Another potential idea: a number of the "CUV's" or "cute-utes", those little FWD biased car-based SUV type things with no low-range have a gerotor pump based clutch type differential. One axle shaft spins faster than the other, the pump builds pressure and applies it to the piston driving the clutches, jamming them together and applying torque to the slower axle. Very limited in power transfer, as the slower the speed differential, the less power it can transfer. They are available in the center position to drive the rear axles (only power rear axles when fronts are slipping fast enough to build pressure). This type might be best - no ring gear, generally. Put between the motor output shafts directly, or on the first stage of RPM reduction, the speed differential will be magnified between the two sides. There are sometimes double-pump units in the rear axle that basically do the same thing - each pump only applies power to its respective axle shaft when the ring gear is spinning fast enough to build pressure in them. That type would be less useful, as with 1 motor per corner you need no ring gear - unless you want to connect the front and rear axles mechanically so any given slipping wheel can transfer torque to the others that still have traction.

Hmm - interesting idea: Triple tor-sen/true-trac/quaife/other geared type limited slips. One each front and rear, and one in the middle. One BAS per corner, driving a pulley bolted between the CV shaft and the respective output shaft of the differential. You get your power at each corner, but if that corner lifts, it can transfer power mechanically as well as via more overload on the other motors.

All of these ideas might be too much complexity for too little gain, though. Just running one per corner could work fine. Kind of depends on the terrain thingstodo is looking to run on, and how light the vehicle is. Momentary overloads on the outer two motors during corners may work great. I only worry about performance on icy pavement in a corner, as I've heard a locker causes a higher probability of a spinout if you have to add throttle in the corner.

Good point about bi-directional tensioning for regen.

https://en.wikipedia.org/wiki/Gilmer_belt is good for hundreds of horsepower, mating a GMC 6-71 supercharger with a Donovan block hemi for AA-Fuel.

Also see final belt drives on Harley motorcycles that have replaced chains. No tensioner.

General:

I'm getting way off-topic with this mechanical stuff, I think. This thread is for control strategies per OP HaroldinCR, yes? I'll bow out on the mech side for now, unless HaroldinCR doesn't mind the digression.

[thingstodo]

Originally Posted by cajunfj40

The "higher torque available to the slower motor" issue could cause similar behavior. The inside wheel gets more torque because it is slipping more than the outside wheel (assuming both motors are loaded, so both are going slower than commanded speed), while the body rolls away from said wheel, unloading it. Once the traction drops below what is needed to keep the tire from slipping due to torque, it lets go. No max overspeed, because AC, that's nice. The whole vehicle slows down a bit since it isn't being driven by that wheel anymore. Now the outside wheel is going even slower than commanded, so slip goes up. Thus torque goes up. Traction is higher than it was on the inside (all else being equal, body roll will do this), so it takes longer to let loose, but when it does, now both wheels on that end of the car are spinning and it's sliding out. Again, this would probably happen faster on slick surfaces.

The point being, without an "open" differential, when one tire lets go the other gets the rest of the torque, making it more able to break traction. Hmm. Maybe slap pulleys on either side of a "truetrac" geared limited-slip differential, and run without a pinion or ring gear at all? I wonder if that'd allow the proper torque biasing.

Hmm. I was under the (mistaken?) impression that transferring torque to the wheel with traction, and not spinning the heck out of the wheel that has just lost traction, is a good thing.

With 4 wheels commanded to turn the same speed, if the inner front one has traction, it pulls you along and you go a bit faster. The other three wheels still have power going to them, just not as much since the have less slip. If the front inner tire loses traction, you should still have traction on the two rear and the front outer, and you go a bit slower. If you break loose with all 4 tires ... 4 wheel skids are not fun ... but perhaps you were a bit aggressive in your driving style for conditions?

I am not a racer - my experience is somewhat lacking here. I just don't want to get stuck in mud, one wheel spinning madly while the other three sit there.

You still don't want it to slip. The tensioner just keeps the "slack" side of the belt from flopping around. If you want reverse and/or regen braking you will want a "set the tension by setting the distance between the pulleys" setup, else the belt will always slip on reverse and/or regen as the slack swaps sides. A really strong tensioner could work, but might need to be impractically strong to function properly, leading to too much side load on the pulleys.

Good point. I will likely have little regen in the simple case.

Is there an off-the-shelf mechanism that uses 2 belts on a dual pulley system, where one belt is tensioned to 'pull' at the drive pulley and the other belt is tensioned to 'push' at that same pulley, using idlers of some sort?

That likely does not make any sense without a sketch. I'll add one tonight.

You may be better off with one motor and the driveline out of something like a Subaru or a 4x4 ATV. Used LEAF motor? Car-part has them as low as $445. More than 4x $85, but you get to use existing driveline parts...

Perhaps a Subaru AWD would be a better fit for me. But I'm not a mechanic. If I can solve a problem electrically instead of mechanically, I will. The ATV linkages, suspension parts, etc are out of the price range for now. They cost as much as many 4x4 truck parts.

I have little info on Leaf drivelines. Do they use an open differential and activate brakes to transfer torque to the wheel with traction? I would not object to using Leaf parts, I just need to learn a bunch of stuff. There are no wrecks up here to pull from. Leaf drivers seem more careful than Tesla drivers

[HaroldinCR]

I have NO problem with mechanical stuff here. Just wait until I get ready to start trying to make a 2 speed electronic transmission. Y'all are in for some REAL sufferin.

If I remember correctly, 1 motor for 1 controller works pretty well like a differential. One wheel takes the load, the other just tags along. Just use 1 throttle.

Now, I gotta try to remember where I read that.

Thingstodo, I have a whole complete Leaf system, with wiring harness, controller, AC compressor, motor/differential with axles, all bolted to original sub frame. You just have to move across the border to save on shipping.

[thingstodo]

Originally Posted by HaroldinCR

I have NO problem with mechanical stuff here. Just wait until I get ready to start trying to make a 2 speed electronic transmission. Y'all are in for some REAL sufferin.

I look forward to it! It can hardly be worse than what Mercedes put into the Smart4twos. I think those would have been much better if the designers had been forced to drive the cars when they were done!