ME0907 getting a bit hot on motorbike

[charlesb123]

After about 30mins running on load covering about 25 miles with some hills, my motor is getting up to about 130celcius, and I have the gen4 controller set to cut back current. I'm not quite sure if I have the correct fan, the enclosed photo shows it running clockwise viewed from the fan side. Can anyone confirm it's right?
The standard fan doesn't seem very efficient.
Any suggestions on keeping it a bit cooler, most of the time I'm well under the 80amps rated continuous.
I could force more air through with ducting, but I think the worst heat generation is at low speeds under high load.
I also wondered if the fan would work any better with the plastic cover removed as it does look quite restrictive, I can easily make a safety mesh screen.

 

[bearing]

That fan should spin counter clockwise viewed from the camera.

 

[justlooking]

That fan should spin counter clockwise viewed from the camera.

if it is made to pull air through the motor then yes, but if its made to push/force air through the motor then no,

looking at the shape of the blades i would say that it is designed to push air through the motor, so it must turn clockwise ,,

as for taking off the plastic cover, no ,, if you remove it then the blades will not blow air through the motor,

 

[bearing]

A radial fan will always pull air from center. If it spins the wrong way, it will still pull, but not as efficient.

 

[charlesb123]

I did some more research, and the difference is that a forward sloping radial fan will produce higher pressure, but lower flow, so a backward is needed for this application. John from Motenergy doesn't produce a clockwise backward sloping fan, but he does a straight radial which will be better than what I have at the moment. I'm also going to make a more open cover to help flow a bit more air as well - it isn't actually needed at all for the fan to work, it's purely a centrifugal fan, there is no shaped air outlet.

 

[liveforphysics]

That fan should spin counter clockwise viewed from the camera.

That's a common misconception, but wrong. That fan is setup for clockwise rotation to draw warm air out of the center of that motor and eject it radially.

Blower blade orientation is pretty counter-intuitive.

 

[Bluefang]

Its probably getting hot as you are probably putting more constant power thru the motor then it can handle? Those motors love to be sold on the peak power rating(30kw) and from reading other posts about it is no where near the actual constant rating.

 

[John in CR]

That fan should spin counter clockwise viewed from the camera.

That's a common misconception, but wrong. That fan is setup for clockwise rotation to draw warm air out of the center of that motor and eject it radially.

Blower blade orientation is pretty counter-intuitive.

It can spin either way and exhaust radially, but CCW makes more sense to me for this implementation. With an installation that's going to see exterior air flow, and significant air flow resistance through the motor, forward curved blades won't be as effective while in motion. Plus they are noisier. If it's spinning CCW then the blades are reverse curved which can pull greater pressure and be less subject to disruption from the exterior air flow. If it's CW rotation then that could be part of why it's getting hot, and it would likely work better with a housing that shields the blower from the exterior wind and directs the exhaust rearward. Then forward curved blades may be fine. If is is being used CW, then I'd wager that they based the decision on a static spinning test of flow, or maybe even just a flow volume without considering the flow resistance through the motor.

 

[liveforphysics]

I respectfully have to disagree my friend.

Forward swept blades will do all things better related to airflow in this situation.

There are many resources to read up on the differences. Here is a concise short one:

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5467360&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5467360

 

[John in CR]

I respectfully have to disagree my friend.

Forward swept blades will do all things better related to airflow in this situation.

There are many resources to read up on the differences. Here is a concise short one:

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5467360&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5467360

That link is talking about axial fans, unless it requires a login and I'm not seeing the meat.

If I understand this wrong, I want to learn, but back when I was researching to learn about centrifugal fans, it seemed to be pretty mature industrial airflow systems stuff. Maybe what I was looking at is old school and needs updating, but the main thing that turned me away from the forward curve type was that performance was highly dependent upon a housing as stated here on page 2 http://www.aerovent.com/docs/fan-en...acteristics-of-centrifugal-fans---fe-2400.pdf.

 

[charlesb123]

Well, I sent the drawings for the motor to a colleague at Siemens who got his motor expert to have a look. They reckon that this type of motor with a very simple rotor and fixed windings has little disruption of air through the motor casing, as the air only has to cool the fixed wiring and very little heat is developed in the rotor. He recommends a backward swept rotor, so the straight radial will have to do for me. He said that with the standard style of mains AC motor the pressure required to efficiently draw air through the centre of the motor can be very high, but they generally still use straight blades for universal applications, and separately driven fans for positions with poor air access or if the motor runs too slow for effieicnt cooling. He is going to lend me a hot wire anenometer so I can do some test and see what's best.
His final comment was that I should really be externally cooling with nice big fins, maybe clamp on fins like you can get for RC motors?

 

[John in CR]

That makes sense. The forward swept is what you see on the squirrel cage fans for an A/C system. When I'm talking about flow resistance I'm comparing to free flow ducts for air, and they can be quite sensitive to flow restrictions at all. eg if you put a well shaped 90° bend within 1 diameter of the air intake to the blower, you can reduce flow by 50%.

FWIW, I've gone straight radial on mine too for simplicity and I may end up going with rotation the other direction.

Also FWIW, the one in the pic above seems to have the blades a bit too swept back to me for CCW rotation. I think that kind of angle would be for fairly extreme rpm, and maybe it's stronger than it looks, but I wouldn't want to be near it at too high rpm.

John

 

[athlon]

another thing you can check are the motor parameter


if phase inductance and gains are wrong inside the sevcon the motor can get very hot even at low power