Gen Set Improvements

[OldManfE]

I recently installed several compact 24.5kW (continuous rating) gen sets. Space and weight are very big considerations as well as reliability. These units are turbo charged diesel, vertical 4-cycle, 4 cylinder, 2.0L liquid cooled units. They seem to have substantial vibration which the maker says is normal. Fuel consumption is about 2 gallons per hour.

This is not my thing. The units work well but what are the possible set of improvements that I can go back to manufacture with and ask for. I may need 50 of these in the future. Thanks for your help on this.

 

[patprimmer]

Depending on the source of the vibration and the methods already applied or optimised:-

Use inline 6 cylinder engines.

Run at an rpm that has minimal vibration.

Change bore stroke, crank length to reduce vibration at required rpm.

Change compression/chamber shape to slow and stabilise combustion.

Change fuel injection pressure/nozzles/timing to slow and stabilise combustion.

Use a petrol engine.

Incorporate balance shafts.

Use more sophisticated engine mounts, like hydraulic dampened units.

Use a flexible coupler between the engine and generator.

Increase weight of flywheel, torsional vibration damper or block.

Regards
Pat
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[MikeHalloran]

The natural imbalance of an inline four can be mitigated by addition of balance shafts. It's not something that anyone would do for 50 engines. If the fours you got have balance shafts and still shake, there's something wrong.

An easier way to go, that doesn't need the engine maker's cooperation, is to fit better engine mounts, tuned to allow the engine to move around without transmitting much vibration to the substrate.



Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

Agree with the above. Rule of thumb is that if the second order (twice engine rpm) is less than 5g measured on the block you don't have a problem, more than 20g and you have to be careful.

Since you are running at a single speed you can optimise the powertrai mounts for that speed alone.

Note that a petrol engine of the same stroke etc will vibrate just as much at second order.

Is it a trade secret exactly which units these are? 50 engines is enough that the manufacturer will at least pay attention to your questions.

Cheers

Greg Locock


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[OldManfE]

Gentlemen, thanks for your suggestions. We definitely can work on the mounts which were fairly standard items (simple rubber blocks). As for the vibration we are working with the manufacturer to get all of the rotating items better balanced. We can't change to gas, it must be diesel because of the customer requirements. I also like the idea of the flexible coupling between motor and generator.