Marine propulsion – Screw propeller – Shafting
Reexamination Certificate
2001-12-27
2003-02-04
Avila, Stephen (Department: 3617)
Marine propulsion
Screw propeller
Shafting
C440S112000
Reexamination Certificate
active
06514108
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The invention relates to an ocean-going ship, and an ocean-going vessel with a stern tube seal arrangement for sealing a stern tube for a propeller drive shaft, and an arrangement for sealing propeller drive shafts in an ocean-going vessel.
2. Background Information
Seal arrangements for ships of this type are known in a multiplicity of embodiments. In actual use it has been shown that during operation by way of axial oscillations of the shaft the associated bushing is moved to and fro. Thus, oscillations of approximately 11 Hertz arise in the case of larger vessels. This causes overpressures and negative pressures in the lubricating oil chamber in relative short time periods, because a pressure equalization by way of the stern tube bearing and the conduits up to the upper tank is substantially not possible.
The overpressure or the negative pressure, respectively, in the lubricating oil chamber affects the seal rings to a large extent. In connection with this there often arises a large loss of oil into the stern tube. The large strain placed on the seals gives frequently rise to operational problems.
OBJECT OF THE INVENTION
It is the object of the present invention, in at least one embodiment, to improve the seal arrangement embodiment of the type described and to minimize in a simple manner oil pressure fluctuations and to avoid functional problems arising because of oil pressure fluctuations.
SUMMARY OF THE INVENTION
The invention teaches that this object can be accomplished by an ocean-going ship, said ship comprising: a propeller; a shaft mounted for rotation of said propeller; bearing means to journal said shaft; a bushing mounted on said shaft; said bushing having a first end immersed in water when said ship is afloat on water, and a second end opposite said first end near said bearing means; a plurality of seals mounted on said bushing; said plurality of seals comprising lip seals; a plurality of annular elements to maintain said plurality of seals in spaced apart relationship on said bushing; said plurality of annular elements being configured and disposed to provide a plurality of first annular chambers for lubricant to lubricate at least said bearing means; said bushing comprising an annular surface at said second end thereof; said annular surface at said second end of said bushing being configured and disposed to form a portion of a second annular chamber for lubricant to lubricate said bearing means; said plurality of seals being configured and disposed to minimize ingress of water and to retain lubricant for said bearing means in said second annular chamber; at least one seal of said plurality of seals being configured and disposed adjacent to said bearing means; a sensor; said sensor being configured and disposed to sense at least one parameter representative of pressure variations of a lubricant in said second annular chamber due to axial oscillations of said shaft; said sensor being further configured to produce a signal representative of pressure variations of a lubricant in said second annular chamber due to axial oscillations of said shaft; a comparator element; said comparator element being configured and disposed to receive signals representative of pressure variations of a lubricant in said second annular chamber due to axial oscillations of said shaft; said comparator element further being configured to compare signals representative of pressure variations of a lubricant in said second annular chamber due to axial oscillations of said shaft with desired pressure conditions; a control element; said control element being configured and disposed to receive signals from said comparator element to effectuate compensation for pressure variations of a lubricant in said second annular chamber due to axial oscillations of said propeller shaft; an expandable and contractable element; said expandable and contractable element being configured to be filled with a pressure medium and to exert pressure on a lubricant in said second annular chamber to compensate for pressure variations of a lubricant in said second annular chamber due to axial oscillations of said propeller shaft; said comparator being further configured to pass signals, to said control element, to effectuate compensation for pressure variations of a lubricant in said second annular chamber due to axial oscillations of said propeller shaft; and said control element being configured to control the extent of filling of said expandable and contractable element to thus adjust pressure conditions exerted upon a lubricant in said second annular chamber with a phase shift of approximately 180 degrees for an actual lubrication pressure condition in said second annular chamber; thus forming an arrangement to compensate and to minimize lubrication pressure fluctuations, of a ship's stern tube seal arrangement, due to Coaxial oscillations of said propeller shaft.
The invention also teaches that the foregoing object can be accomplished in a ship by an arrangement to compensate lubrication pressure fluctuations in a ship's stern tube seal arrangement due to axial oscillations of a ship's propeller shaft, said arrangement comprising: a shaft mounted for rotation of a ship's propeller; bearing means to journal said shaft; a bushing mounted on said shaft; said bushing having a first end immersed in water when the ship is afloat on water, and a second end opposite said first end and adjacent to said bearing means; a seal arrangement configured and disposed to minimize ingress of water and to retain lubricant for said bearing means; a lubricating arrangement configured and disposed to provide lubricant to said seal arrangement and to said bearing means; a sensor; said sensor being configured and disposed to sense at least one parameter representative of pressure variations in said seal arrangement due to axial oscillations of said propeller shaft; said sensor further being configured to generate signals representative of pressure variations in said seal arrangement; a comparator element; said comparator element being configured and disposed to receive signals, representative of pressure variations in said seal arrangement, from said sensor; said comparator element further being configured to compare signals representative of pressure variations in said seal arrangement with desired pressure conditions; a control element configured and disposed to receive signals from said comparator element to effectuate compensation for pressure variations in said seal arrangement due to axial oscillations of said propeller shaft; and an expandable and contractable element; said expandable and contractable element being configured to be filled with a pressure medium and to exert pressure on a lubricant in said lubricating arrangement to compensate for pressure variations in said seal arrangement due to axial oscillations of said propeller shaft; said comparator being further configured to pass signals, to said control element, to effectuate compensation for pressure variations in said seal arrangement due to axial oscillations of said propeller shaft; and said control element being configured to control the extent of filling of said expandable and contractable element to thus adjust pressure conditions exerted in said lubricating arrangement with a phase shift of approximately 180 degrees for the sensed lubrication pressure in said lubricating arrangement; thus forming an arrangement to compensate and to minimize lubrication pressure fluctuations, of a ship's stern tube seal arrangement, due to axial oscillations of said propeller shaft.
The invention further teaches that the foregoing object can be accomplished by an arrangement to compensate lubrication pressure oscillations in a ship's stern tube seal arrangement due to axial oscillations of a ship's propeller shaft, said compensating arrangement comprising: a sensor configured to be disposed to sense at least one parameter representative of pressure oscillations, in a ships's stern tube s
Avila Stephen
B+V Industrietechnik GmbH
Nils H. Ljungman & Associates
LandOfFree
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