Walk-thru w/Pictures - Hand-building a Spark EV Motor

[MitchJi]

Hi,

Background - link and a brief excerpt from a review:
http://www.caranddriver.com/reviews/2014-chevrolet-spark-ev-first-drive-review

GM builds its own oil-cooled permanent-magnet electric motor for this Spark at a plant in Baltimore, a motor it promises will appear in another, as yet unnamed, product in the pipeline. Take note: One day it could be remembered as the small-block of the electric segment.

Instant Electric Torque, and Lots of It
It spins out 105 kW (140 horsepower) and a strong 400 lb-ft of torque. That latter figure, especially, makes us think it's past time the Society of Automotive Engineers (SAE) weighed in with a standard for reliable comparisons, but once you drive it, there's no question this motor's got muscle. Car and Driver estimates the Spark EV can reach 60 mph in fewer than eight seconds

Hand-building the motor - link with a few excerpts and a few pictures (to see most of the article you need to use the link):
http://blog.caranddriver.com/we-build-the-chevy-spark-ev’s-ac-permanent-magnet-motor/

Pete Savagian, GM’s chief engineer for electrical equipment, is of the opinion that the only way to really understand how electric motors work and the best means of manufacturing them is the hands-on method. So GM dropped its guard for a few hours, had a select few journalists don gloves and safety glasses, and turned us loose at Wixom to build motors....

In essence, the stator is a tube consisting of electrical steel and copper. The steel portion has a high silicon and iron content and consists of many thin plates called laminations. Slots in the laminations are first lined with insulating sleeves made of paper and then filled with approximately 20 pounds of copper. Instead of using round-section wires, GM’s design for the Spark’s motor fills the stator slots with rectangular-section copper bars. (The roughly 3-by-4-mm bars have a higher surface-to-volume ratio than round wire, which optimizes both their electrical and cooling characteristics.)....

GM uses a two-lever press to form the copper bars to the desired shape. After loading a straight chunk of varnish-coated copper bar stock into the die jaws, I gave the first handle a hefty swing followed by a pull of the second lever. Upon returning those handles to their original positions, the finished product—what looks like a hairpin for Andre the Giant—is ready for further processing.

The next step is carefully loading 120 of those hairpins into the correct stator slots. There are eight types of pins and they fit closely together, so care is needed to get the location and sequence perfect. After the pins are started, they’re shoved home—seated all the way inside the stator—in a hydraulic press exerting more than 1000 pounds of force to overcome the friction between the copper bars and the paper insulators.

Another automated press pushes and turns the protruding bars into their final shape. During a few minutes in another automated fixture, varnish is carefully dribbled into stator voids to make sure that the bar-to-laminate insulation and attachment is complete. Filling the voids to eliminate relative motion is crucial to make sure the motor runs quietly, dependably, and without thermal issues. After attaching leads and conducting electrical tests, the stator is a finished component....

 

[Punx0r]

It's rare to see such an interesting and informative article from an automotive magazine

 

[yopappamon]

Hand made motors is probably a good indication the Spark EV will only be a California compliance vehicle and not be sold nationally.

 

[Punx0r]

The article seemed to suggest that this production was to prove the processes for a larger, more automated facility. Hopefully that is true...

 

[gogo]

The article seemed to suggest that this production was to prove the processes for a larger, more automated facility. Hopefully that is true...

Automated, programmable bending machines have been around for more than 25 years.

 

[yopappamon]

The article seemed to suggest that this production was to prove the processes for a larger, more automated facility. Hopefully that is true...

I hope that's true, I would like to be able to have one available here locally.