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Old 04-02-2009, 01:51 AM   #742 (permalink)
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Originally Posted by Intrigued View Post
HUH??? Am I getting too old school here? I've never met a car that had a direct drive A/C. What do they drive it off of, the timing chain???
Modern compressors have the motor directly turning the compressor. In fact, most modern compressors have the motor and actual compressor permanently welded together in a box (hermetic compressor). It is cheaper to weld the parts together than it is to make a leak-tight seal with bolted pieces, so bolted construction (serviceable compressor) is only used when serviceability outweighs the extra cost.

But since it appears that we're dealing with an old serviceable compressor originally designed for belt drive (can you please show a picture to clarify?), is there a way to remove the pulley and fit a coupler to directly connect it to the motor? In particular, belt drive would be a bad idea for a brushed DC motor. If the belt breaks, the motor would spin too fast and possibly burn out unless there's a protection circuit. (In contrast, a brushless DC or AC motor would just harmlessly run without a load.) I suppose you could glue some magnets to the motor pulley and use a pickup coil to detect the motor speed. If it exceeds a limit, power off the motor. (That'll also allow for PLL-type control of motor speed.)
They were going on about how these compressors would use so much less horsepower when it wasn't needed, to help with fuel economy. This was about 20 years ago, so I'm guessing they've come up with more efficient compressors...
The most common compressor used today is the scroll compressor. Copeland is the leading manufacturer of scroll compressors.
If America manages to eliminate obesity, we would save as much fuel as if every American were to stop driving for three days every year. To be slender like Tiffany Yep is to be a real hypermiler...

Allie Moore and I have a combined carbon footprint much smaller than that of one average American...
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