[Mike Dabrowski 2000]

If the motor is hotter than the block, heat flows out of the motor. The block is cooled by the antifreeze.
The small fins on the rotor and the tight proximity of the surfaces and a small fresh air inlet make the spinning IMA motor circulate air.
I would call that air cooled with a warm block as a passive conductive cooler.
Neither is a very effective cooler, so the idea of putting in some liquid cooling like Chris did on his dual motor setup is probably a good idea on a quad setup.

 

[Hugh-Falls]

Quad Stack

We all know that the whole is something more than the sum of its parts. At present my stacked IMA motor is a bunch of parts and "there are many slips between the cup and the lip", so no "in progress photos" of parts.

1.) If the power cable lug protrusion is cut off and the area leveled, the dowels will key the cases together nicely and the bolt holes will also line up for through rods to hold the assembly together.

2.) A flanged full length keyed shaft mounts the Insight flywheel/sensor/clutch assembly, rotors, and bearings. In my case, this shaft is machined from a Chevy '81 pick-up rear axle which is an excellent flanged steel forging. Other axles should also be adequate.

3.)The rotors are mounted to the 1-3/16 diameter keyed shaft using standard industrial power transmission components. Adapters are machined from a standard #35 pitch sprocket with "#1610 taper bore bushing". The adapters fit the flywheel pilot diameter of the rotor and use the same bolt holes and indexing dowel. The ID of the rotors are enlarged to accept the 1-3/16 diameter shaft: this requires a few swipes of a file on each of the six crankshaft mounting screw lugs. A drill jig was made using a #60 sprocket with "split taper bushing (has internal and external keys)" to drill the dowel and bolt holes in adapters to insure easy accurate reproducibility. The #35 sprockets were mounted on 4" long keyed stub shafts for machining and subsequent drilling (the drill jig was keyed and mounted to each stub shaft for drilling).

4.) The stack, starting at flywheel assembly, consists of an empty case with intact power lugs and sensor assembly; a 1/2" bearing plate carrying the front bearing cartridge which supports the motor shaft and absorbs clutch release bearing thrust; four stacked stators/cases; and an end plate machined for stator clearance carrying the rear floating bearing cartridge and drilled for motor mount. At present, shaft extends beyond rear bearing.

5.) Spacers are required between the rotor assemblies to maintain correct stator/rotor relationships. Assembly will be attempted using Mike's shim method with heavy duty drafting Mylar sheet shims and a case lowering fixture, one layer at a time.

IF and WHEN the motor is assembled and works, photos will be posted.

 

[Eli]

Wow, looking forward to seeing this.

Sounds like you're making some good progress. But I want to see pics even if it doesn't work.

 

[Mike Dabrowski 2000]

A bit of topic,
I just had a nice long conversation with a guy in Walton Kansas that has been building EV conversions since the 70's
EV-Blue.com, Electric Vehicle Questions and Answers, EV-Blue.com, EV Blue, Electric Blue, evblue, evblue.com

He is just finishing up an Insight .
He used a Netgain 9" brushed DC motor with 12- 12VAGM lead acid 27 batteries, and custom springs to carry the 450 lbs.

He asked me if I was interested in buying any of the Insight parts, he has the engine with IMA attached, all of the IMA stuff including the battery pack.
May be worth a trip to his place if you live in the area, and need any of the stuff?

 

[MN Driver]

Group 27 AGM's? This car begs for a lithium pack, 450 pounds and probably a 40 mile range after the peukert effect to dead if lucky and 15 or less if he wants the batteries to last and all the weight? I have respect for Wayne but putting lead into an Insight boggles my mind. It seems to make some sense for the lead sled pickup trucks where he can load 900 pounds of lead in the back, but for a small car? At least he used AGM's but they are going to be about 100Ah cells. The same weight could easily get 100+ miles of safe discharge range with a lithium pack and much nicer performance too.

 

[Eli]

Yeah, but probably at least 2x the cost...

 

[Hugh-Falls]

Please redo the math

Gentlemen:
After going to the "Blue" website and reading your replies above, reaching some of those range/weight conclusions seem improbable with a 144V brush type DC motor installation.

For $12000 plus, you should hope to get more for your money than 1970's lift truck technology.

 

[retepsnikrep]

1.) If the power cable lug protrusion is cut off and the area leveled, the dowels will key the cases together nicely and the bolt holes will also line up for through rods to hold the assembly together.

I noticed that which is nice.

Hugh I appreciate your reticence about posting photos but we are desperate to see the work in progress for ideas and inspiration. The chevy axle thing seems intersteing but unless i see a pic i have no idea what we are talking about.

I think there are three/four of us now actively looking at a stacked motor setup. Chris has done some great work and so have you by the sound of it. We are not wanting to judge or criticise what you have done. It's a tricky project and has several solutions i'm sure.

Having been looking at the stator attachment points inside the alloy case I doubt that transfers much heat direct to the case through conduction itself. Must be the circualtion or air in the case which moves heat from the stator to the alloy case. With that in mind I will probably go with a pressure air blower system pushing/sucking air through from say one end to the other. I'll have temp sensors on each stator and an infra red sensor on the rotor farthest from blower.

Mike like your ideas as well need to talk to my friendly machine shop.

Re the Insight EV conversion i think that's a missed opportunity, any conversion nowadays using DC series motor and lead acid is prettty old fashioned 30 year old technology. Huge weight penalty as well.

 

[Hugh-Falls]

Cooling air circulation

Having been looking at the stator attachment points inside the alloy case I doubt that transfers much heat direct to the case through conduction itself. Must be the circualtion or air in the case which moves heat from the stator to the alloy case. With that in mind I will probably go with a pressure air blower system pushing/sucking air through from say one end to the other. I'll have temp sensors on each stator and an infra red sensor on the rotor farthest from blower.

It would be ideal to expose each individual layer to same temperature cooling air. Cooling air is planned to be introduced to each layer simultaneously through the opening in each of the four cases through which the commutation sensor leads had formerly passed. It may be possible to find an existing four cylinder tuned exhaust manifold that would fit but it is more likely that it will be necessary to modify or fabricate a custom air inlet manifold and outlet collectors using standard mandrel bent exhaust tubing components to also fit the circulating blower.

There is a rubber capped passage near the top of each case through which a temperature probe could be inserted to measure each individual stator temperature. The heated air would be circulated out through both the end plates at the rotor area. A heat exchanger (a salvaged car heater assembly with filter) can be used to reclaim the heat unless some of the existing Insight radiator can be ducted easily as part of the closed circuit stack air cooling system which would also include inverter cooling. A filter is needed because the cooling air circuit will not be hermetically sealed and there will be some seeping outside air exchange.

The IR sensors that you mention could be located at both the end plates to read rotor temperatures. It would be useful also to measure the temperature there of the air leaving the motor.

Maybe one of our members can tackle speculating about the amount of heat that will have to be removed from the system. Thermodynamic calculations are way beyond my expertise and comfort zone and I would appreciate even a rough estimate if someone could make the effort.

 

[retepsnikrep]

Based on my earlier experience with lithium EV's and the 40ah car and having pushed a full 40ah of capacity through a single ima motor in a little over an hour i never experienced any motor or mdm problems. Average current ~ 30A for 1hr 15mins average power say 4kw at 144v nominal.

I would estimate without engine drag that 6-8kw would provide enough power for 60mph crusing speed without problems. 4 motors will be at an average of around 15-20A each for 8kw of power. That's nothing in the grand scheme of things.

Short bursts of around ~20kw per motor could be expected with a suitable battery and some final tweaks to the MDM setup giving a pretty nippy 80kw peak power

Based on all this I do not have any undue concerns about cooling, and a simple air in one end, air out the other end, with a heater scroll type fan should be more than suffcient IMHO. Ducting this warm air for heater use would be sensible if it can be fed into the air intake somehow. I look forward to seeing the other solutions though.

There will also be some (not much) heat available from the 4 stacked MDM units which i will modifiying and mounting directly above each motor in some fashion, again if this heat can be ducted that will help. A ceramic heating element inserted in place of stock heater matrix will almost certainly be reqd IMO as heat generated will be pretty low.

Temp sensing is all part of the package of course

 

[Mike Dabrowski 2000]

EV-Blue, did indicate the lead was selected due to cost , but I had the same questions as to why lithium was not selected.
The guy has been doing a lot of conversions, 175 in 1980 and understands the electronics and batteries he has been using for the past 20 years, so of course he works with what he knows best, may not be optimum, but it still works.
He has another Insight to do in the near future, and will be in contact with me about the Synergy drive project that I really wish I had the time to work on.

While we would love for the stacked motor to not require any active cooling, I think that ChrisMA's approach to water cooling the stack is the way to go. Winter driving in an EV that has no heat is not much fun, so I would go through the trouble of putting in an antifreeze and water pumped system with the ability to put the generated heat into either a heater core for heating the cabin with fan or a small dump radiator for dumping the heat in summer. The same with the drive electronics. That is where the big heat is generated. make the air cooling system so the exhaust air can be vented in or out of the car. I got to see how much heat came out of the inverter when the WWU x-prize car was here. A one mile drive got the inverter heat sink so hot it would burn skin when it was operated without cooling air.
Keep at it.

 

[Hugh-Falls]

Insight EV heat management system

I would estimate without engine drag that 6-8kw would provide enough power for 60mph cruising speed without problems. 4 motors will be at an average of around 15-20A each for 8kw of power. That's nothing in the grand scheme of things.

There will also be some (not much) heat available from the 4 stacked MDM units which i will modifying and mounting directly above each motor in some fashion, again if this heat can be ducted that will help. A ceramic heating element inserted in place of stock heater matrix will almost certainly be reqd IMO as heat generated will be pretty low.

Temp sensing is all part of the package of course

1.) Why not keep as much of Insight climate control plumbing as intact as possible and continue to use a water based heat transfer method? Keep radiator, heater and air conditioning as is. Add an electric water circulating pump and a drive motor for the AC pump.

2.) Air "in" at the stators and "out" through the rotors appears to be the simplest method for cooling the stator windings and the rotor magnets. Use a stripped Insight heater with blower, filter, and controls as a heat exchanger to recover motor heat. Air cooling would be a closed circuit.

3.) Fabricate 1" thick drilled aluminum water cooled heat sinks and mount an MDM on each side making it possible to mount two pairs of MDMs in an enclosure in the limited space atop the stack and recover the heat directly in the water. An additional wet heat sink is needed for DC/DC converter.

4. An external 12 volt block heater would be added to provide heat as needed. A plug-in adapter to a household power source could be used to preheat the system in cold weather.

 

[retepsnikrep]

I think the main problems are there won't be very much heat and it won't be very high quality i.e. not very hot. A lot of effort to recover perhaps 1kw of heat if running at 10kw load. To recover that meagre 1kw from motor and mdm and transfer it effectively to the wet system is just not practicable IMO. Moving the slightly warmed but more directly useful air about i see as a possibility with some cheap ducting. I'll be removing the aircon from my car anyway as i never use it.

The dc-dc converter can probably be mounted on a single heatsink exposed to the air flow at the front of the motor stack where throttle body and water radiator etc are now.

I have successfully used a 2kw US hair dryer in my van for heating. A fan heater matrix inserted into the air box can do the same thing and yes I used to preheat the car/van interior from the mains a few minutes before setting off.

 

[MN Driver]

About 30 minutes of a 1.5kw heater running in the back of an Insight is about all that is needed for -10f(-25c) temperatures to be comfortable when setting off to about 10 minutes into the trip where the amount of air required to keep the front glass from fogging up makes the interior cold. Of course with electric heating that air to the windsheild would be heated and it wouldn't need to be as warm when setting off. 15 minutes from the grid would more than take care of it for reasonable comfort if starting from a garaged area and the windsheild is already clear of fog and ice. If there is iced fog and snow/ice on the outside, 1.5kw would be far too little to remove it. Most US hair dryers are closer to 1500 watts because our 120 volt 15 amp bathroom circuits can't quite handle 2kw and some leeway is needed for other appliances like battery powered shavers and the like to charge. I've venture a stacked set of 3kw should do it, although I'd almost be inclined to have 4.5kw available to clear the windows for when parking outdoors and getting an ice glaze on the outside and frost inside. I'd rather ditch the costly electric heating and use a fuel for that, seems to suite the purpose better but safely integrating something like that in a car is something I don't know if I could figure out, I'll probably stick with electric heating.

 

[Mike Dabrowski 2000]

The batteries would not like those temperatures either, so they may require heating as Peter was considering ??
Anyways the answer will come with some real world experience.
Nothing worse than anticipating a problem, and going through a lot of work with a solution, just to find it was a non problem.

 

[Hugh-Falls]

Insight EV heat recovery

Peter: The studies done on the Prius and Toyota Camry hybrid by the Oak Ridge Labs found efficiencies of the combined motor/inverters to be above 90%, so your estimate of about 1 Kw to be available for recovery at best, is about right.

In cold weather, the stack may shed enough heat passively so as not to need any additional cooling at all. However, in hot weather, the cooling will probably be needed and a closed circuit filtered air circuit would be a good way to accomplish that and a heat exchanger is a good way to transfer that heat, especially if it can be done easily using a stripped Insight heater assembly.

Here in the South, the air conditioning system is important for comfort and it will be kept active. The virtues of the existing Insight hot water heating system are self evident and an effort will be made to keep it operational. Some of the ideas discussed in the "Thermos" thread could be used.

MnDriver: Your experiences in the great Frozen North suggest that for comfort and safety, a lot more heat than previously thought necessary may be required. Evidently you feel that some source of heat other than electricity may be useful to consider. My experiences with early gasoline heaters and the later ones used in the 60's Chevy Corvairs were less than satisfactory. You conclude that electric heat may still be a be a better choice at this time. Loss of range or additional batteries do appear to be a compromise we will have to make.

The existing Insight radiator has probably at least 5 times more heat dissipating capacity than will be required but it serves as a support for the A/C condenser and may be retained but not be a part of the heat recovery setup. As you have both suggested, there is a lot more heat capacity needed for safety and comfort than is available from heat recovery. My preference is to stick with the OEM wet heating system, recover as much heat as possible using water, and devise a method for being able to add heat to the water on demand.

 

[retepsnikrep]

Whats are peoples thought on not using any thrust bearings on the stacked motors? I do not intend to have a clutch so there should be no pressure on the end of the motor.

I'm guessing 2nd gear for starting off and max acceleration and 5th gear for crusing. When you come to a stop there won't be any changing down and motor will probably pull in 5th from very low mph.

I've done the no clutch thing before in a series motor powered dc conversion that seemed fine.

 

[Hugh-Falls]

Bearings

Whats are peoples thought on not using any thrust bearings on the stacked motors? I do not intend to have a clutch so there should be no pressure on the end of the motor.

The Sealmaster Skwezloc mounted bearings used in my quad stack IMA motor are considered to be radial/thrust bearings. The bearing at the flywheel end of the stack was selected mainly to locate the shaft/rotor assembly in the stacked housing and incidentally to absorb clutch release thrust. The other similar shaft bearing at the other end of the stack was also mounted rigidly to the shaft but allowed to float axially in the housing to permit lengthwise displacement of the shaft bearing due to thermal expansion and other stresses that may occur due to the differences in the materials used in the construction of the housings (aluminum) and shaft/rotors assembly (steel).

The Insight clutch and the existing OEM parts are retained as is. Many in the EV community feel that the presence of the clutch is an asset. My view is "Why re-engineer something that works?" The drive line from and including flywheel/sensor disc/sensors is retained intact. The selected radial/thrust bearing has more than enough thrust capacity to withstand the light Insight clutch release thrust loads. There is a weight and inertial penalty connected with re-use of clutch disc/clutch release bearing/flywheel parts and it is a matter of personal preference to retain them.

 

[Hugh-Falls]

Stacked IMA motor cooling

These soggy 95 degree plus days get you thinking about cooling. I've decided to discard the spacer ring which was fastened to the motor mount end plate and served to provide space for the stator protrusion. In its place will be a stripped/empty IMA case. Then there will be enough additional space to mount a flat pancake cooling coil to the end plate. This arrangement will place the cooling coil within the IMA motor stack and in the same location as the water jacket of the former Insight engine.

Fortunately there is enough excess shaft length and the tie rods are still their stock three foot length so discarding the spacer ring is no great loss and the extra inch or so of stack length should still fit.

The cooling coil may never be necessary or could prove inadequate but in either case it is not a very difficult addendum. Easier to change now than later.

 

[Hugh-Falls]

Stacked Ima Motor Tie Rods

For a neat clean and simple installation, the stacked IMA motor tie rods must not only be able to hold the stack together but also be able to be used to mount the stack to the transmission. The tie rods can be machined to be able to hold the stack together and then be extended to make the connection to the transmission one tie rod at a time.

There are six M12x1.25 bolts holding the transmission, IMA motor, and IC engine together. Four are threaded into the transmission and two are turned the other way around to thread into the engine. The holes in the IMA case through which the bolts pass are 13mm diameter (about 0.512" Dia.).

The bolt holes are very accurately located and line up well enough so that six B-7 grade 1/2-20 threaded rods can pass through the stack neatly. On the quad stack, the empty case that mounts to the transmission has 1/2-20 Helicoils tapped into the six bolt holes on the face that formerly mounted to the engine (the 13mm bolt holes are very close in size to the recommended tap drill size for these Helicoils). The tie rods are screwed into these 3/4" long Helicoils to hold the stack together. Four of the tie rod ends are turned down to 12mm (.472" Dia.) and threaded M12 x 1.25 for a length of about 1-5/32. This will give about 1/2" of clean metric thread length before some metric thread width starts to be lost due to pitch differences between the 12mm and 1/2" thread. The 12mm thread length is followed by a 3/4" length of intact 1/2-20 thread followed by a 2-1/8 " length at 7/16 Dia. (threads cut away) and the rest of the rod has intact 1/2-20 threads. Two nuts are tightened together and can act as a bolt head during installation if needed.

The way this works: The four 12mm threaded end tie rods are threaded through the Helicoils until the 3/4" length of intact 1/2-20 thread is within the 3/4" long Helicoil (the 12m x 1.25 threaded section is beyond the Helicoil). This is done by eye as the stack is being assembled. The other two unmodified tie rods are simply threaded through the Helicoils. The stack is assembled and the tie rod nuts are torqued at the end of the stack............. For assembly to transmission, the two unmodified tie rods are screwed out through transmission lugs and secured with washers and nuts both at the transmission and on the stack end one by one. One by one, the modified rods are screwed on through the Helicoils and will then move freely to be threaded into the transmission and nuts are applied to tie rod ends to hold stack and transmission together one by one.

As the stack is assembled to the transmission, tension on the stack is released from only one tie rod at a time and is restored before going on to the next tie rod.