48 volt Direct Drive PM Alternator Assembly

[SPSInc]

Looks good Henry. Did you run a feeler gauge around the rotor to check for clearance? Or just spin the rotor by hand to make sure nothing is rubbing? Since the stator is mounted to a J609 mounting face it shouldn't be a problem but always good to be safe.

Let me know if you have any other questions.

Eric

[Henry W]

Hi Eric,

Thanks for the help this afternoon.

I did not use feeler gauge. I did not even think of it. I did spin it and it seems fine.  Like you said it is mounted to a J609 mounting face and it should not be a problem. The fit was very snug on the mounting face and since I forgot to check the clearance I will hope for the best.

Bob, I will work on shipping both of your Eagle Pitcher housings Monday or Tuesday so you can start planning your project.

I measured the footprint of the unit and it is close to 16" X 16". I say that is very compact. One thing I don't like is the muffler near the alternator. I think the best thing to do is try to find a differant exhaust system. I guess a heat shield can be built but I would feel better getting the exhaust away from the alternator.

Here is another picture.

More Later.

Henry

[Henry W]

How did you manage to move the rotor with out it sticking to something it was not supposed to???

Tom,

Removing it was easy once I figured out how it could be done. I made a handle and installed it on the SH bushing. Once installed I sat down and and started pulling and the magnetic force was so strong I was having problems getting the bushing to slide on the shaft. So, I braced myself and gave it one good swift jerk. It came off clean without rubbing.

It was easy to install. That handle I made earlier, I just  re-mounted it on the SH bushing and braced myself and slowly moved the rotor to the stator. once I got close the magnetisum self aligned it for me. It just might of been my day.

My guess is there is a proper puller to install and remove them.

Henry

[Henry W]

I just converted the small military trailer I have as a test bed to work on this project. The Vangaurd/PMA unit is resting on the trailer. I will take some pictures hopefuly tomorrow.

Henry

[Henry W]

Here are more pictures.

[Henry W]

Two pictures show how close the muffler is to the PMA. I feel a little uncomfortable with this setup. I feel I should find a differant setup. Overall the unit is very compact for what it is able to put out.

Henry

[Henry W]

I found some exhaust options in the PDF attachment below.

[DanG]

'N' Grade Rare Earth magnets begin to lose strength when heated above their maximum operating temperature - around 165-170°F (75°C). Yes sure, those may be H or SH, EH or UH blah blah grade and good to higher temperatures before they begin to fade, but without knowing the OEM specs you're stuck using the lowest absolute maximum temperatures. If I remember correctly from looking at the original set up, they isolated the PMG pretty far away from the engine. Having the casing danger close to the oil sump and the short stub drive shaft wholly encased in PMG housing seems to be asking for trouble... And that's BEFORE the losses in the windings begin to self-heat the unit.

[SPSInc]

The muffler you have on that engine is a standard B&S catalog muffler. This clearance is closer that I'd like to see but in reality when running it won't be that bad. The main thing that will need to be done is to make sure the alternator can pull in cool air. The alternators fan will pull air in through the end where the terminal block is attached. The air is then pushed out through the cooling fins. Unfortunately the engines cooling air moves the opposite direction. It blows its hot air at the alternator. When the engine is running there should be enough air moving by the muffler to keep the heat transfer to the alternator at a minimum. When the engine stops and the air stops moving you will then see some heat soak into the stator housing. I have attached some pictures of some mufflers that I have that would elevate the position of the muffler away from the alternator.

As for the magnets they are class H. With as much capacity (HP) as the engine has you won't stress the alternator enough to over heat it. You should be able to get @ 5KW on LP. DanG is right about the danger of the alternator closely attached to the crank case. The alternator will absorb the heat of the engine. The alternator was designed with this in mind. Again the key thing will be to baffle the alternator so that it pulls in cool air and not recirculate the hot engine cooling air. If you do that you shouldn't have a problem. It has been done like this for a lot of generators.

[Henry W]

Thanks for the info Eric and DanG.  

A large freash air inlet tube in front of the terminal block sounds like a good thing.

Eric, where can I get one of those silver exhaust systems you posted? I like it.

Henry

[SPSInc]

Henry,

I use them in my generators. I have them custom built for me. I could sell you one if interested. Attached is a 3D view showing the extra clearance it would provide.

EA

[Henry W]

Eric, That is perfect and I would like to purchase one. I will send you a PM when I get a chance this afternoon.

Thanks,

Henry

[Henry W]

Here is the new muffler installed. I say it is a great fit for this application.

Thanks Eric,

Henry

[mobile_bob]

that looks nice!

i like it!

bob g

[Ronmar]

I think I would still look into a heat shield...  Under load, that muffler is going to radiate a lot of heat.