Patent Publication Number: US-6033271-A

Title: Ship drive with a driving engine and a directly driven propeller shaft

Description:
BACKGROUND OF THE INVENTION 
     The present invention concerns a ship-propulsion system comprising a drive mechanism and a shaft directly connected to it and provided with a propeller. 
     Ships propelled by systems with only one drive mechanism can be subjected to considerable hazard when the mechanism malfunctions or fails. In the worst cases, the ship can become unmaneuverable and even totally lost. The maneuverability of ships that carry hazardous or very environmentally deleterious goods must in particular be guaranteed in emergencies. 
     The simplest solution is to install an accessory drive mechanism in the propeller shaft. Such accessory drive mechanisms include a motor that drives the shaft or propeller by way of a transmission, and the shaft must be uncoupled from the defective main drive mechanism by a separating mechanism. The thrust provided by such accessory or emergency drive mechanisms for application to the hull of the ship is much weaker than that of a main drive mechanism. 
     Such a approach can be inferred from the Lohmann &amp; Stolterfoht prospectus, FLESALUS RDE 75153, published December 1993 and describing a &#34;flexible&#34; emergency ship-propulsion system. A pneumatically powered cogged clutch separates both the drive mechanism and the propeller, neither of which is illustrated. The coupling simultaneously acts as a bearing in transmitting the propeller&#39;s thrust. There is a drawback to this approach, however, in that there is play in the clutch and the resulting vibrations are difficult to deal with. Another drawback is that the clutch and bearing together require a special base to introduce the forces into the hull. 
     Known from Swiss Patent 173 968 is a combination ship-propulsion system wherein for example a piston device and a turbine can be engaged with a propeller shaft. To prevent damage to the drive mechanism if the shaft suddenly stops, a safety-ensurance clutch between the transmission and the propeller entirely disengages the shaft form the rest of the mechanism when a specified angular momentum is exceeded. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is accordingly a ship-propulsion system that has a drive mechanism and a directly driven propeller shaft and an accessory drive mechanism for auxiliary or emergency operation with a weaker propeller thrust that can be introduced into the hull without play on the part of the components of the separating mechanism, eliminating the need for a separate base. 
     The core of the present invention is the combination of an in-itself known non-play clutch (cf. L&amp;S Mitteilung 84, September/1982) and a non-play auxiliary thrust bearing that can be engaged when the ship is in auxiliary or emergency operation. The auxiliary thrust bearing transmits the diminished propeller thrust to another thrust bearing accommodated in the drive mechanism. The clutch is preferably an in-itself known hydraulic conical bolt-actuated clutch. The auxiliary thrust bearing is specifically designed to prevent the clutch&#39;s components from being affected by the propeller thrust, ensuring non-play positioning of all parts. 
     The advantage of the present invention is that angular momentum is transmitted definitely independent of thrust, whereby in both cases the absolute freedom from play of the individual components is of primary significance due to the wide fluctuations in angular momentum and thrust typical of conventional drive mechanisms with two-stroke engines. Another advantage of the present invention is that, since the clutch does not require a separate base, both thrust bearings, the one in the drive mechanism and the auxiliary thrust bearing coupled to the clutch, cannot affect each other. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the auxiliary thrust bearing in accordance with the present invention will now be specified with reference to the accompanying drawing, wherein 
     FIG. 1 is a longitudinal axial section through a ship-propulsion system in accordance with the present invention and 
     FIG. 2 is a section along the line A--A in FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a longitudinal section along the axis of part of a ship-propulsion system in accordance with the present invention. A drive mechanism 50 with a thrust beating 51, usually a longitudinal rotary diesel, is connected to an integrated auxiliary thrust bearing 3 by a driving-end flange 1 and by a shifted non-play clutch 2, which will be further specified hereinafter and which is provided with an integrated auxiliary thrust bearing 3. The particular connection between intermediate propeller shaft 4 and the main propeller shaft with the propeller mounted on it is not illustrated. All that is essential is that the connection is a &#34;direct&#34; drive mechanism, whereby the particular desired propeller speed is attained by regulating the speed of the drive mechanism itself. There is accordingly no need for a transmission between this main drive mechanism and the propeller 52. An accessory drive mechanism ensures continued maneuverability of the ship in the event of failure on the part of the main drive mechanism. The accessory drive mechanism includes an electrical device 42 that can be operated as either a motor or as a generator as desired. Device 42 is connected to a transmission 5 by a clutch 43. The transmission 5 in the present embodiment is an intake transmission and has a large cogwheel 6 mounted on a sleeve 7 that surrounds intermediate propeller shaft 4. Transmission 5 is connected to intermediate propeller shaft 4 by a highly resilient clutch 8. Clutch 8 is connected to intermediate propeller shaft 4 by an annular flange 9. Shifted clutch 2 and auxiliary thrust bearing 3 are secured by a thrust shaft 10 accommodated between intermediate propeller shaft 4 and driving-end flange 1. 
     Shifted non-play clutch 2 is a conventional bolt-actuated clutch. It comprises an outer annular flange 11, an inner annular flange 12, an annular retaining flange 13 and conical bolts 14. A ring-securing flange 15 secures and positions conical bolts 14, which are forced against it by special nuts 16. How far shifted non-play clutch 2 can open is determined by a bolt 18 that is provided with a stop 17. Details of the hydraulically powered motion of conical bolts 14 have been excluded from the drawing as inessential to the present invention. The angular momentum of the engaged bolt-actuated clutch 2 is transmitted to thrust shaft 10 and intermediate propeller shaft 4 by a U-shaped cross-section flange 19 connected to shaft 10 by a threaded connection 20. 
     A non-play auxiliary thrust bearing 3 is in accordance with the present invention integrated into in-itself known bolt-actuated clutch 2. Non-play auxiliary thrust bearing 3 will now be specified in detail. The driving-end flange 1 on the drive mechanism 50 is fastened to an annular flange 22 by a threaded connection 21. Annular flange 22 is itself fastened to the aforesaid outer annular flange 11 on bolt-actuated clutch 2 by another threaded connection 23. The annular flange 22 on non-play auxiliary thrust bearing 3 rests against thrust shaft 10 by way of bearing 24. A tight collar 25 can rest against the inner surface of annular flange 22. Axial displacement is provided by one taper on thrust shaft 10 and another in collar 25. Collar 25 is axially positioned by a counternut 35 mounted on a threaded section of thrust shaft 10. Collar 25 is secured on the other side by a bent flange 26 that rests against thrust shaft 10 by way of a bearing 27. An annular disk 28 is accommodated between bent flange 26 and collar 25 and another annular disk 29 between collar 25 and annular flange 22. Annular disks 28 and 29 are provided with pressure blocks 53. Bent flange 26 is fastened to annular flange 22 by screws 30. This connected is secured by a nut 31. There is a pre-tensioning ring 32 between nut 31 and annular flange 22. Pre-tensioning ring 32 acts in conjunction with a counternut 33 that can be tensioned and released by an adjusting mechanism 34. Although adjusting mechanism 34 is not illustrated in FIG. 1, the detail in FIG. 2 represents one possible embodiment. 
     How bearings 24 and 27 are lubricated will now be specified. With bolt-actuated clutch 2 disengaged and driving-end flange 1 stationary, lubricant is introduced through a radial channel 36 in driving-end flange 1 to a bore 37 extending along the axis of thrust shaft 10 and thence through channels 38 and 39 that diverge radially out of the shaft to bearings 24 and 27. Driving-end flange 1 also contains another radial channel, channel 40, that opens into space 41 between it and thrust shaft 10. Fluid is pumped into space 41 to help separate non-play auxiliary thrust bearing 3.