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US3774883A Expired / Lapsed US ⏱️ 0.0 years remaining

Constant tension line-tensioning mechanism

Assignee: MARKEY MACHINERY COMPANY Inc A WA CORP
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Filing: 1972-10-26
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Granted: 1973-11-27
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Expires: 1992-10-26
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Abstract

Abstract Constant line tension can be maintained in a ship''s mooring or towing line extending from a winch by supplying to a polyphase phase-wound induction motor driving the winch alternating current from an alternating-current source the frequency of which is variable in response to the load on the winch. Such variablefrequency source may be an alternator driven by a phase-wound induction machine powered to operate as a motor. The variablefrequency AC source is connected to the winch motor to drive the winch only in the reeling-in direction, but the tension on the line can retard the motor speed or stall the motor or rotate the winch and motor in the opposite, paying-out direction against the reeling-in torque of the motor. The winch motor torque can be adjusted by varying the value of resistance shunted across the rotor winding of the winch motor. The line can be retrieved very quickly by having a squirrel-cage alternating-current motor connected mechanically to the phase-wound induction machine. During constant-line-tension operation, such motor is simply idly rotated with such machine, but for rapid line retrieval the motor can be powered by the same AC supply as powers the phase-wound induction machine and such motor will then drive the phase-wound induction machine positively to operate as an alternator. During such operation the field windings of the phase-wound electrical machine are connected in reverse phase relationship to the AC supply and the rotor windings are connected to the stator windings of the winch motor. Also, for towing applications the voltage of the variable-frequency source can be altered in response to variations in the length of line paid out or reeled in to control the winch motor in turn in response to sensing the extent of rotation of the winch drum in paying out or reeling in the towing line and correspondingly varying the field excitation of the alternating-current generator supplying current to the winch motor to operate the winch motor for restoring the line to its original length.

Inventors

  • 👤 C Ostrom

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-02 02:09
CPC Classifications
B; B66; B66D; B66D1/00; B66D1/28; B66D1/40; B66D1/48; B66D2700/00; B66D2700/01; B66D2700/0108; Y; Y10; Y10S; Y10S254/00; Y10S254/90

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 305 words
In line-tensioning mechanism incluDing line-winding means connected to a line, an electric line-winding means motor continuously connected to supply continuous mechanical torque to the line-winding means for winding in such line whenever the mechanical torque on the line-winding means produced by the line tension tends to drop below the mechanical torque produced on the line-winding means by the line-winding means motor, an electric power source normally continuously connected to the line-winding means motor to provide electric current thereto continuously for producing mechanical torque on the line-winding means tending to reel in line whether the line-winding means motor is stopped or turning in a line-reeling-in direction or turning in the linepaying-out direction, and load-responsive means responsive to the electric current load on the electric power source resulting from the mechanical torque produced by the line-winding means motor on the line-winding means and operable to vary an output characteristic of the electric power source automatically in response to variation in mechanical torque exerted by the linewinding means motor on the line-winding means resulting from changes in line load and corresponding variation in electric current load on the electric power source, the improvement comprising the electric power source including a first alternator normally connected to supply electric current to the line-winding means motor, an alternating current electrical machine having a wound rotor, operable selectively as a motor and as a second alternator and mechanically connected to drive said first alternator when operating as a motor, means for electrically disconnecting said first alternator from the line-winding means motor and connecting the rotor winding of said alternating current electrical machine to the line-winding means motor when said electrical machine is operating as a second alternator, and driving means connected to said alternating current electrical machine for driving the rotor thereof mechanically when said machine is operating as a second alternator.
Claim 2
Dependent Claim 305 words
In line-tensioning mechanism incluDing line-winding means connected to a line, an electric line-winding means motor continuously connected to supply continuous mechanical torque to the line-winding means for winding in such line whenever the mechanical torque on the line-winding means produced by the line tension tends to drop below the mechanical torque produced on the line-winding means by the line-winding means motor, an electric power source normally continuously connected to the line-winding means motor to provide electric current thereto continuously for producing mechanical torque on the line-winding means tending to reel in line whether the line-winding means motor is stopped or turning in a line-reeling-in direction or turning in the linepaying-out direction, and load-responsive means responsive to the electric current load on the electric power source resulting from the mechanical torque produced by the line-winding means motor on the line-winding means and operable to vary an output characteristic of the electric power source automatically in response to variation in mechanical torque exerted by the linewinding means motor on the line-winding means resulting from changes in line load and corresponding variation in electric current load on the electric power source, the improvement comprising the electric power source including a first alternator normally connected to supply electric current to the line-winding means motor, an alternating current electrical machine having a wound rotor, operable selectively as a motor and as a second alternator and mechanically connected to drive said first alternator when operating as a motor, means for electrically disconnecting said first alternator from the line-winding means motor and connecting the rotor winding of said alternating current electrical machine to the line-winding means motor when said electrical machine is operating as a second alternator, and driving means connected to said alternating current electrical machine for driving the rotor thereof mechanically when said machine is operating as a second alternator.
Claim 3
Dependent Claim 44 words
In the line-tensioning mechanism defined in claim 1, the driving means being continuously connected mechanically to the alternating current electrical machine for driving of the driving means by the alternating current electrical machine when the alternating current electrical machine is operating as a motor.
Claim 4
Dependent Claim 16 words
In the line-tensioning mechanism defined in claim 1, the driving means including a squirrel-cage induction motor.
Claim 5
Dependent Claim 58 words
In the line-tensioning mechanism defined in claim 1, the alternating current electrical machine being a phase-wound induction machine including a stator winding and a rotor winding, one of said windings being connected to the line-winding means motor to serve as a power supply therefor, and an alternating current supply connected to the other winding of the electrical machine.
Claim 6
Dependent Claim 33 words
In the line-tensioning mechanism defined in claim 4, the driving means including a squirrel-cage induction motor electrically connectible to the same alternating current supply that is connected to the alternating current electrical machine.
Claim 7
Dependent Claim 29 words
In the line-tensioning mechanism defined in claim 1, and means for continuously mechanically connecting the rotor of the first alternator and the rotor of the alternating current electrical machine.

References Cited (Backward Citations)

US3421736A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-11-26 1977-05-28 1977-11-27 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-11-26 1981-05-28 1981-11-27 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-11-26 1985-05-28 1985-11-27 $7700.00 Window Closed / Lapsed

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