US3812411A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dynamic braking of a gas turbine powered ship propulsion system utilizing a d.c.electric drive
Assignee: United States Department of the Navy
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Filing: 1973-02-20
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Granted: 1974-05-21
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Expires: 1993-02-20
Abstract
Abstract Dynamic braking of a ship''s propeller powered by a turboelectric drive system is achieved by dissipating the rotational energy of the propeller through the windage loss of the gas turbine rotor. Braking torque on the propeller is maximized by controlling the generator field current according to a predetermined profile so as to maximize armature braking current without exceeding rated armature current or rated rotor speed.
Inventors
- 👤 R Johnson
- 👤 C Rubis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:47
CPC Classifications
H; H02; H02P; H02P3/00; H02P3/06; H02P3/08; H02P3/12
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
256 words
An electromechanical propulsion system for a ship''s propeller utilizing dynamic braking comprising, in combination: a gas turbine including a rotor; a homopolar d. c. electric generator and a homopolar d. c. electric motor, said generator being mechanically coupled to said turbine rotor and electrically coupled to said motor, said motor being mechanically coupled to said propeller; electrical energy coupling means between said turbine rotor and said propeller which, during propulsion, transmits energy produced by said turbine to drive said propeller and, during dynamic braking of said propeller, transmits energy from said propeller to drive said rotor of said turbine in the same direction it was moving during propulsion for dissipating the propeller''s energy through rotor windage loss; wherein said turbine rotor is mechanically coupled to the armature of said homopolar generator, the armature of said homopolar generator is electrically coupled to the armature of said homopolar motor, and the armature of said homopolar motor is mechanically coupled to said propeller so that said motor functions as a generator during braking of said propeller, thereby developing a reverse electromagnetic braking torque on said propeller, while said generator simultaneously functions as a motor, thereby driving said turbine rotor; and further including generator field current profile means for controlling, according to a predetermined profile, the current in said generator field coil circuit during braking, at a value which will compatibly maximize both armature current, up to armature current rated value, and power delivered to said turbine rotor up to rated windage loss at rated speed of said turbine rotor.
Claim 2
Dependent Claim
256 words
An electromechanical propulsion system for a ship''s propeller utilizing dynamic braking comprising, in combination: a gas turbine including a rotor; a homopolar d. c. electric generator and a homopolar d. c. electric motor, said generator being mechanically coupled to said turbine rotor and electrically coupled to said motor, said motor being mechanically coupled to said propeller; electrical energy coupling means between said turbine rotor and said propeller which, during propulsion, transmits energy produced by said turbine to drive said propeller and, during dynamic braking of said propeller, transmits energy from said propeller to drive said rotor of said turbine in the same direction it was moving during propulsion for dissipating the propeller''s energy through rotor windage loss; wherein said turbine rotor is mechanically coupled to the armature of said homopolar generator, the armature of said homopolar generator is electrically coupled to the armature of said homopolar motor, and the armature of said homopolar motor is mechanically coupled to said propeller so that said motor functions as a generator during braking of said propeller, thereby developing a reverse electromagnetic braking torque on said propeller, while said generator simultaneously functions as a motor, thereby driving said turbine rotor; and further including generator field current profile means for controlling, according to a predetermined profile, the current in said generator field coil circuit during braking, at a value which will compatibly maximize both armature current, up to armature current rated value, and power delivered to said turbine rotor up to rated windage loss at rated speed of said turbine rotor.
Claim 3
Dependent Claim
19 words
The combination of claim 1, wherein, the field coils of said homopolar generator and said homopolar motor are superconducting.
Claim 4
Dependent Claim
37 words
The combination of claim 1, including: means to activate said current profile means for commencing said predetermined current profile in said generator field circuit in response to a change in a particular parameter of said propulsion system.
Claim 5
Dependent Claim
32 words
The combination of claim 3, wherein: said parameter is the common armature current of the homopolar generator and motor, and said change is a reversal in direction of said common armature current.
Claim 6
Dependent Claim
40 words
The combination of claim 4, including: a variable voltage supply in the generator field coil circuit for supplying current to said field coil; wherein said current profile means is coupled to said variable voltage supply for controlling the voltage thereof.
Claim 7
Dependent Claim
32 words
The combination of claim 5 wherein said current profile means includes: a programmable function generator coupled to said variable voltage supply; and said means to activate is coupled to said function generator.
Claim 8
Dependent Claim
55 words
The combination of claim 6 including armature current comparator means for comparing a signal proportional to actual armature current with a signal proportional to rated armature current and for supplying an output signal coupled to said function generator to effect a decrease in armature current when said armature current equals or exceeds its rated value.
Claim 9
Dependent Claim
54 words
The combination of claim 7 including rotor speed comparator means for comparing a signal proportional to said actual rotor speed with a signal proportional to rated rotor speed and for supplying an output signal coupled to said function generator to effect a decrease in rotor speed when said rotor speed exceeds its rated value.
Claim 10
Independent Claim
107 words
A method of dynamically braking a ship''s propeller which is driven by a turbine powered d. c. electric generator motor drive system including the steps of: cutting power to said turbine; transmitting the energy in said propeller via said d. c. electric drive system to said turbine; and dissipating said energy in the windage loss of the rotor of said turbine by controlling the current in said generator field circuit according to a predetermined profile so as to compatibly maximize both armature current, up to armature current rated value and power delivered to the rotor of said turbine up to rated windage loss at rated rotor speed.
Claim 11
Independent Claim
107 words
A method of dynamically braking a ship''s propeller which is driven by a turbine powered d. c. electric generator motor drive system including the steps of: cutting power to said turbine; transmitting the energy in said propeller via said d. c. electric drive system to said turbine; and dissipating said energy in the windage loss of the rotor of said turbine by controlling the current in said generator field circuit according to a predetermined profile so as to compatibly maximize both armature current, up to armature current rated value and power delivered to the rotor of said turbine up to rated windage loss at rated rotor speed.
Claim 12
Dependent Claim
33 words
The method of claim 9 including the steps of: initiating the step of controlling the current in said generator field circuit in response to a change in a particular parameter of said system.
Claim 13
Dependent Claim
24 words
The method of claim 10, wherein: said parameter is the armature current; and said change is a reversal of direction of said armature current.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |