new member and have a non typical application

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bohica2xo
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Re: new member and have a non typical application

Postby bohica2xo » Sun Sep 02, 2018 5:44 pm

Ice, I have learned a lot from you over the years.
I had to go look it up - my first foray in to the (MVAC) oil separator game was in 2003. We discussed it in 2005 here:
https://www.autoacforum.com/messageview.cfm?catid=2&threadid=12821

That motorhome ran for almost a decade on that SD7 compressor after all of that. They replaced the compressor during an engine overhaul in 2011. In 2017 the coach was a total loss after multiple frame cracks were discovered during an inspection. Still pumping cold air.
danev2
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Re: new member and have a non typical application

Postby danev2 » Thu Sep 06, 2018 10:18 am

I thought I would come back to the discussion, the MD 369 and 500 used to use an allison 250. We now run a Rolls C30 engine.
and... I just got a green light to evaluate a design option for mounting the compressor on the engine, off the PTO pad, next to the starter.
I am also evaluating, based on wise cousel, the sanden TRSE compressors. the engineering challenge I need to figure out? the PTO speed is 6000 rpm.
So I might need a gear reduction to slow it down. and it being a direct drive... a disengage function.
AND I will need to completely retune the system, from a compressor running 2K to one running 6K or close.
Maybe thats not a big deal.
What the possibility of that installation does however, is help enormously with weight and balance, and oil control. the compressor, evaps and condenser are all about the same height that way. Instead of the compressor being 5 feet! highter than everything else.
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bohica2xo
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Re: new member and have a non typical application

Postby bohica2xo » Thu Sep 06, 2018 12:16 pm

There are clutchless automotive compressors that spin full time. The output is controlled electrically.

If you are sharing a pad with an existing item I have seen "Y" type couplers with gearsets inside. Probably possible to get your reduction that way.

B
ice-n-tropics
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Re: new member and have a non typical application

Postby ice-n-tropics » Thu Sep 06, 2018 2:04 pm

bohica, iron sharpens iron.
We shared some really good AC engineering together over the years! Hope you get to Texas or I visit Las Vegas some sweet day.That was some important training for me for book authorship since I failed English. You gotta love the challenge of solving AC problems.
danev2
Sure you must have a way to take the compressor off line. Bohica is talking about how clutchless compressors , especially on some European cars runs the compressor shaft continuously by reducing displacement down to 2% for winter. The clutch is replaced by a direct drive that includes a useful torque mechanism that freewheels when tha compressor locks up.
Direct drive: Be aware that Sanden uses serrated shaft not splined shaft.
hotrodac
danev2
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Re: new member and have a non typical application

Postby danev2 » Thu Sep 06, 2018 3:53 pm

ice-n-tropics:
I will look into the clutchless, why not. at this point my design option are quite large. thank you
"a direct drive that includes a useful torque mechanism that freewheels when tha compressor locks up"
almost sounds like a lockup torque converter.
Weight might be an issue there.
DV
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bohica2xo
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Re: new member and have a non typical application

Postby bohica2xo » Thu Sep 06, 2018 4:28 pm

Ice:
I am usually wandering around SEMA every year. Get your employer to send you there for "Research"...

danev2:
Ice is talking about the frangible drive spider in those compressors. If the compressor seizes up the spider fails so that the serpentine belt does not break. Probably a useful thing to have, so that a compressor failure does not tear up the accessory gear box with an unexpected torque load...

Ice had mentioned a sanden that would take 8,000 rpm - perhaps that is a place to look if you have 6k pads
ice-n-tropics
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Re: new member and have a non typical application

Postby ice-n-tropics » Fri Sep 07, 2018 2:25 pm

Wanted to attend SEMA.
The clutchless compressors usually have a weight advantage because the field coil winding and armature plate are eliminated. The system must be optimized to prevent compressor failure at low displacement OCR year round operation. I received a month of training on VDC and Clutchless compressors from the German Dr. Engineers near Frankfurt (when they were sober).
Only engineers that Japan respects are Germans (not Americans), but if you are very critical they will begrudgingly give you a very little respect.
hotrodac

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