Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H23/00—Transmitting power from propulsion power plant to propulsive elements
  • B63H23/32—Other parts
  • B63H23/34—Propeller shafts; Paddle-wheel shafts; Attachment of propellers on shafts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H23/00—Transmitting power from propulsion power plant to propulsive elements
  • B63H23/32—Other parts
  • B63H23/321—Bearings or seals specially adapted for propeller shafts
  • B63H2023/322—Intermediate propeller shaft bearings, e.g. with provisions for shaft alignment

Definitions

• the present invention relates to a method and a device for continuous and automatic monitoring and align ⁇ ment of the propeller shaft of a ship in operation.
• a propeller shaft should transmit a torque from the engine to the propeller.
• the shaft is supported by a num ⁇ ber of bearings. Static and dynamic loads are taken up in the vertical and horizontal planes. The deflection of the shaft (shaft line) determines the load distribution between the bearings as well as the bending stresses in the shaft.
• Static bearing loads (the shaft weight) and bending stresses are balanced by affecting the deflection by alignment of the shaft. Such an alignment is carried out in connection with the installation or repairing of the shaft. Three or more bearings are required.
• the alignment is achieved by elevating or depressing different bearings a few millimetres at the most, in relation to a horizontal reference line, with an accuracy of a few tenths of a millimetre.
• the reference line is related to the stern tube bearing.
• Computer programs are used for calculating a (in- fluence matrix) and solving the equation system (1).
• the solution is obtained by "trial and error" with different offsets x as input data.
• the propeller shaft is installed in sections. Each section is placed on two bearings. To obtain the calcu ⁇ lated offsets and the required shaft line, each bearing is elevated or depressed by means of jacks and adjusting screws. The bearing position is checked with the aid of sophisticated measuring equipment.
• spacer plates are inserted between the bottom plate of the bear- ing and the foundation, whereupon the bearing is fixed.
• the spacer plates are specially ground for each bearing.
• the plate thickness should give the bearing the desired offset.
• EP-A-015 654 is known a method for predeter ⁇ mining the position of the parts in a structure before mounting the parts. With the aid of optical instruments provided with sights, the positions of abutments are established in relation to reference surfaces. This method can be used for obtaining the correct inclination of a vessel engine.
• WO87/01439 is known a device for controlling the static position of a shaft in a certain point.
• a light beam is reflected by a prism fixed on the shaft towards a receiver.
• the light beam gene ⁇ rates an electric current, the strength of which depends on the angle of incidence.
• the current intensity is com ⁇ pared with a desired value.
• EP-A2-405 777 are known a method and a device for measuring a shaft line.
• a laser beam is directed at at least two sensors fixed on the shaft. By comparing signals generated in the sensors, deviations from the initial shaft line are determined.
• the shaft line When calculating the shaft line, one takes into account imagined conditions during operation and stand ⁇ still, hot and cold states, respectively. Generally, the offsets are determined such that the bearing loads are distributed as favourably as possible in the hot state. It is checked that acceptable conditions prevail in the cold state.
• a real and a calculated shaft line seldom agree. Since the bearings are fixed in the foundation, the off- sets and the shaft line are affected by hull deformations due to sea, load, heat etc. In medium-size and large-size vessels, the bearings can be elevated or depressed some centimetres. Since an alignment is carried out with an accuracy of tenths of a millimetre, it is understood that hull deformations give rise to under- and overloads in the bearings. This means wear to the bearings. Unevenly loaded gear bearings cause wear to the gear teeth. In underloaded bearings, "oil whip" (instability) occurs. Realignment is sometimes necessary after a cer ⁇ tain time of seaway.
• One object of the present invention is to provide a method for continuous and automatic monitoring and align ⁇ ment of the propeller shaft of a ship upon hull deforma- tions during operation.
• Optimum shaft line here means a maximally straight shaft line with respect to the pre ⁇ scribed lower and upper limits for bearing pressure, shaft stresses etc.
• a third object of the present invention is to pro ⁇ vide a device for carrying out the inventive method.
• Fig. 1 shows a shaft line
• Fig. 2 shows spacer plates between bearings and foundation.
• Fig. 3 shows a propeller shaft supported by a num- ber of bearings on piston and cylinder assemblies in hydraulic pressure circuits having a common computer.
• Fig. 4 shows a bearing on piston and cylinder assem ⁇ blies having a pressure circuit.
• the device according to the invention is intended to operate in the engine room of a ship in operation.
• the bearing offsets should be adjusted in a manner to compensate for hull deformations.
• the device consists of a piston and cylinder assembly (K) in a hydraulic pres ⁇ sure circuit having a measuring means (M) , a pump (P) and a control means (S) .
• the measuring and control means are connected to a common computer (D) .
• the piston and cylin- der assembly acts between the foundation and the bottom plate of a bearing (L) for a shaft (A) .
• the bearing load (pressure) is given by the pressure in the pressure circuit.
• the pressure is changed upon a hull deformation where the bearing is vertically offset.
• the new pressure pTM 20 is indicated by the measuring means and is supplied to the computer, in which a comparison with desired values is performed.
• a volumetric change AV or a corresponding value is calculated for adjusting the piston. This value is supplied to the con- trol means which starts the pump. The piston is adjusted ⁇ x so as to compensate for the hull deformation.
• the program includes: • calculation of the optimum offsets (optimum shaft line);
• the program gives bearing loads and offsets as a result of an optimisation procedure with respect to permissible ranges for influencing parameters.
• the optimisation pro ⁇ cedure takes place with a target function:
• n - 2 bearings It is assumed that the pressures on n - 2 bearings are available.
• the possibilities of maintaining an optimum shaft line upon hull deformations depend on how many bearings are adjustable. If n - 2 bearings are adjustable, the same shaft line can be constantly maintained. If less than n - 2 bearings are adjustable, a new shaft line is calculated if the foundation is so changed that the old shaft line cannot be maintained or is no longer optimal. The new shaft line gives a new value of the function (2) depending on the subconditions and the number of adjustable bearings.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Sliding-Contact Bearings (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20390301

Family Applications (1)

Country Status (7)

Cited By (4)

• 1993
  • 1993-06-16 SE SE9302075A patent/SE500490C2/sv not_active IP Right Cessation
• 1994
  • 1994-06-14 WO PCT/SE1994/000579 patent/WO1994029170A1/en not_active Application Discontinuation
  • 1994-06-14 AU AU70127/94A patent/AU7012794A/en not_active Abandoned
  • 1994-06-14 KR KR1019950705802A patent/KR960703081A/ko not_active Ceased
  • 1994-06-14 EP EP94919056A patent/EP0702641A1/en not_active Withdrawn
  • 1994-06-14 JP JP7501682A patent/JPH07504635A/ja active Pending
• 1995
  • 1995-12-07 NO NO954961A patent/NO954961L/no not_active Application Discontinuation

Non-Patent Citations (2)

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