PTO/PTI mode with engine running...

Discussion in 'Boat Design' started by ideaEngineering, Jun 30, 2008.

  1. ideaEngineering
    Joined: Jun 2008
    Posts: 4
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Singapore

    ideaEngineering New Member

    hi all

    Anyone care to share the above feasibility?
    I hereby using StainM posting of the drawing for easy understanding.
    Operating PTO mode is no issue.
    For operating PTI mode, the purpose is to help the engine to generate more power for the ballardpull.

    My doubts are as follows:-
    1. While PTI mode; is the generator/motor running at the same rotation or reverse?
    2. If the SG dont use pony motor to start the SG as motor, autotransformer stating method might be the alternative. How the autotransformer kickup the SG as motor?
    3. How would the gear box operation to kick in while the engine are running?

    Any one that had the hand on experience, please advice and thanks!
     

    Attached Files:

  2. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Imagine the fat line between your gear boxes being a rigid shaft and you'll know the answer. The direction of rotation is always the same.
    This works, but wastes energy in the conversion to/from hydraulics or electricity. Consider using a shaft with a visco coupling or limited slip differential.
     
  3. Nojjan
    Joined: Sep 2006
    Posts: 111
    Likes: 4, Points: 18, Legacy Rep: 30
    Location: North Europe

    Nojjan All thumbs...

    I don't understand your idea? How would adding mechanical losses help to increase zero speed thrust? Would you not just waste engergy instead of sending it to the props?
     
  4. ideaEngineering
    Joined: Jun 2008
    Posts: 4
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Singapore

    ideaEngineering New Member

    Responding to CDK and Nojjan

    Hi CDK, I tried searching information in regards to visco coupling an dlimited slip differential via internet, there wasn't much info discuss about this issue.
    Is this concept only apply to automobile (car)?

    Well, while waiting for respond from the forum I had also find out some info in regard to the PTO/PTI.

    Basically while generator in PTO mode the direction would be the same as when change over to PTI mode. The purpose of this PTI mode is to assist the under power engine to work on bollard pull.

    For this case it is not PTH, therefore the engine would still running, when generator change to PTI mode at rated speed, once the clutch engage the speed will increase.

    This can be done by few matter; e.g. autotranformer or pony motor, direction of the generator should be rotating the same when it is in PTI mode.

    Anyway, appreciate you guy respond. Anyone care to share your experience, please do so. Thank you!
     
  5. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Visco couplings were first used in cars by Audi for their Quattro models to distribute the power over 4 wheels. They are also used in miniature form for the mechanical fan in most passenger cars that have no electric fans.
     
  6. powerabout
    Joined: Nov 2007
    Posts: 2,913
    Likes: 62, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    Get a gearbox that can take both engine inputs and both shaft outputs but can be de coupled.
    I have seen one on a megayacht that was used for cruising effiiency on one engine.
    Multi engine Cruise ships also have them
     
  7. ideaEngineering
    Joined: Jun 2008
    Posts: 4
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Singapore

    ideaEngineering New Member

    Hi powerabout

    Yes. we had the conclusion as finally had a meeting with the client that require PTO/PTI mode.

    They had confirm that the generator will not stop and do not had any clutch to de-coupled. Which means they not even require start-up for the generator motor.

    While engine is spinning, control panel will parallel with aux-genset onboard. And change the PTO to PTI mode at the same rotating direction. Of cause the sequence of de-excite of generator etc. would be carry out before it turn to motor mode. And the control would have to be sure of the engine must running at the same speed of generator motor. Otherwise would be like what Nojjan had mentioned here. It would adding mechanical losses...
     

  8. Dynaset
    Joined: Nov 2009
    Posts: 7
    Likes: 0, Points: 0, Legacy Rep: -7
    Location: Finland

    Dynaset Junior Member

    Hydraulic power everywhere

    Look at more: Link
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.