Marine propulsion – Screw propeller – Having transmission
Reexamination Certificate
2000-07-11
2001-10-23
Avila, Stephen (Department: 3617)
Marine propulsion
Screw propeller
Having transmission
C440S111000
Reexamination Certificate
active
06305998
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a marine drive mechanism with a twin-engine distribution transmission.
The Diesel engines in current passenger ships, cruise ships and ferries for instance, are resiliently supported. Naval ships, furthermore, require very quiet hulls to prevent detection by SONAR, and their engines are accordingly also resiliently supported. Engines and transmissions are mounted on a common resiliently supported platform. A pressure bearing rigidly mounted on the vessel's bottom reliably transmits the propeller thrust, and a special displacement coupling transmits torque from the transmission to the propeller while ensuring low hull noise between the transmission and the propeller-shaft train. There is a drawback to marine drive mechanisms of this genus. Although the engines and transmission are resiliently supported well enough to decrease the emission of hull noise, noise can still be transmitted into the hull by way of the propeller-shaft train and easily identified as “water noise”. The ability of SONAR to identify not only the ship's class but the individual ship as well is known.
SUMMARY OF THE INVENTION
The object of the present invention is to improved twin-engine distribution transmission of the aforesaid genus wherefrom essentially no hull noise is emitted and whereby the transmission will not be as long and will be more cost effective.
Since the engines and the transmission are separately supported and since the frequency of the support can be tuned to that of the engines and transmission, the present invention provides the advantages over conventional designs of acoustic decoupling and fine tuning. Hull noise can accordingly be extensively decreased. Positioning the resilient supports on the same level as or on each side of the longitudinal axis of the propeller-shaft train prevents detrimental tilting moments from being exerted on the pressure bearing or on the meshing of the cogs in the equipment. The transmission can even be optimally mounted on three points. It can be accommodated in a shorter space because the conventional and more complicated separate pressure bearing and displacement coupling are no longer necessary. If the resilient supports are on the same level as the longitudinal axes of the propeller-shaft train, the transmission will be much easier to align in spite of thermal expansion, and no special alignment procedures will be necessary.
Several embodiments of the present invention will now be specified by way of example with reference to the accompanying drawing, wherein
REFERENCES:
patent: 3929089 (1975-12-01), Lambrecht et al.
patent: 4978320 (1990-12-01), Chaplin et al.
patent: 5022628 (1991-06-01), Johnson et al.
Rasche Karl
Schafer Wilhelm
A. Friedr. Flender AG
Avila Stephen
Fogiel Max
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