Aircraft electrical system providing emergency power and electric starting of propulsion engines

• US 5,899,411 A
• Filed: 01/22/1996
• Issued: 05/04/1999
• Est. Priority Date: 01/22/1996
• Status: Expired due to Term

• Current Assignee: Sunstrand Corporation
• Original Assignee: Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Dickes, Gary E., Nelson, Jeffrey D., Latos, Thomas S.
• Primary Examiner(s): Jordan, Charles T.
• Assistant Examiner(s): DINH, TIEN QUANG
• Application Number:
  US08/589,235
• Time in Patent Office: 1,198 Days
• Field of Search: 244/53 A, 244/58, 290/55, 290/44, 60/39.142, 60/39.141, 60/39.15
• US Class Current: 244/53.00A
• CPC Class Codes: B64D 33/00 Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
• CPC Class Codes: F05B 2220/50 for auxiliary power units (APU's)
• CPC Class Codes: H02J 2310/44 for aircrafts
• CPC Class Codes: H02J 7/1415 with a generator driven by a prime mover other than the motor of a vehicle
• CPC Class Codes: H02J 7/1423 with multiple batteries

Abstract

An aircraft is provided that includes one or more engines, an air-driven generator, and a start-circuit for operably connecting an electrical output of the air driven generator for starting one or more of the engines while the aircraft is in flight. Various embodiments also provide apparatus for cross-ship electric starting of multiple engines while the aircraft is in flight or on the ground using: an electrical output of a generator attached to another engine; on-board batteries; an on board auxiliary power unit; or power received from a ground source. A single start-converter is utilized to supply power to AC starter-motors for electric starting of the aircraft'"'"'s engines. In some embodiments, the engine is soft-started with the air driven generator, by controlling blade pitch in an air driven turbine driving the air driven generator, without the use of the start converter.

Claims

1. An aircraft comprising:

1) an airframe;

2) a first propulsion engine attached to said airframe for propelling said aircraft along a flight path;

3) a first electric starter motor operably coupled to said engine in a manner allowing said motor to spin-up said engine to a start speed whereat said engine can be started while said aircraft is in flight along said flight path;

4) an air driven electrical generator attached to said airframe in a manner allowing air passing around the airframe when said aircraft is in flight to drive said generator for producing alternating current (AC) electrical power; and

5) engine start-circuit means operably coupling said generator to said starter motor in such a manner that said electric power produced by said air driven generator may be utilized by said starter motor for driving said engine to allow in-flight starting of said engine.

2. The aircraft of claim 1 wherein said engine start-circuit means includes an emergency start contactor for selectively electrically connecting said air driven generator to said starter motor.

3. The aircraft of claim 1 further including:

a) a battery;

b) a start converter having input and output terminals, said input terminal being electrically connected to said battery for receiving DC power therefrom, said converter being configured to convert said DC power into AC power deliverable at said output terminal of said converter; and

c) wherein said start-circuit means includes a start-power source selection switch having a first input electrically connected to receive electric power from said air driven generator, a second input electrically connected to receive AC power from said output terminal of said start converter, and an output electrically connected to said starter motor;

d) said start-power source selection switch including switching means for alternatively connecting said output of said selection switch to said first or said second input of said selection switch, to thereby respectively connect said starter motor for receiving electrical power alternatively from said air driven generator or said start converter.

4. The aircraft of claim 3 further comprising:

an engine driven generator operably connected to be driven by said propulsion engine for producing alternating current;

AC bus means electrically coupled to said engine driven generator and said air driven generator to selectively receive alternating current from either of said air or engine driven generators.

5. The aircraft of claim 4 wherein said AC bus means includes:

a generator relay for selectively electrically connecting said engine driven generator to said AC bus means; and

an emergency start contactor for selectively electrically connecting said air driven generator to said AC bus means.

6. The aircraft of claim 5 further including DC bus means including:

a) a DC bus;

b) means for connecting said DC bus to said battery;

c) a transformer rectifier unit (TRU) having an electrical output connected to said DC bus, and an input adapted to receive alternating current, said TRU being configured for supplying DC power to said DC bus when AC power is supplied to the input of said TRU; and

d) a TRU relay for selectively electrically connecting said input of said TRU to said AC bus.

7. The aircraft of claim 6 wherein said starter motor and said engine driven generator are embodied in a starter/generator configured to alternatively function as a starter motor for starting said engine, and as a generator for generation of electrical power when driven by said engine.

8. The aircraft of claim 6:

further including a second engine having operably attached thereto a second starter motor for spin-up of said second engine to a start speed, and a second engine driven generator operably connected to be driven by said second engine for producing alternating current;

wherein said AC bus means further includes a second generator relay for selectively electrically connecting said second engine driven generator to said AC bus;

wherein said start-circuit further includes start motor selector means for selectively electrically connecting the output of the start power source selection switch alternately to said first or said second electric starter motor; and

wherein said means for connecting said DC bus to said battery is a cross-start contactor.

9. In an aircraft including at least two engines each having operably coupled thereto an electric start motor and an engine driven electric generator, an air driven electrical generator, and a battery, an electric engine start system comprising:

means for supplying electrical power from said battery for starting at least one of said engines;

means for supplying electrical power from at least one of said engine driven electrical generators to the electric starter motor of another of the at least two engines for starting same; and

means for electrically connecting an alternating current (AC) electrical output of said air driven generator to the electric starter motor of at least one of said engines for starting said engine.

10. An aircraft comprising:

an engine;

an air driven generator;

means for operably connecting an electrical output of said air driven generator to said engine for in-flight starting of said engine;

an air driven turbine having variable pitch blades disposed to intercept a flow of air about said aircraft, and configured to produce a rotary output operably connected to said air driven generator for driving said air driven generator;

said air driven turbine including blade pitch actuator means for adjusting the rotational speed of said turbine by adjusting the pitch of said blades with respect to said airstream;

first sensing means for sensing a rotational speed proportional to a speed of said engine and generating a first input signal proportional to said speed;

second sensing means for sensing a parameter of said electrical output of said air driven generator and generating a second input signal proportional to said parameter;

control means for receiving said first and second input signals and generating;

a first control signal applied to said blade pitch actuator means for controlling an output frequency of said electrical output of said air driven generator by controlling said blade pitch and turbine; and

a second control signal applied to said air driven generator for controlling an output voltage of said electrical output of said air driven generator; and

wherein said means for operably connecting includes an electric motor operably connected to drive said engine when supplied with said electrical output of said air driven generator in a manner whereby said motor is driven in a soft-start manner for starting said engine.

11. An aircraft including an apparatus, an electric motor operably connected for driving said apparatus, an air driven generator, and means for operably connecting an electrical output of said air driven generator to said motor for driving said apparatus, said aircraft further comprising:

an air driven turbine having variable pitch blades disposed to intercept a flow of air about said aircraft, and configured to produce a rotary output operably connected to said air driven generator for driving said air driven generator;

said air driven turbine including blade pitch actuator means for adjusting the rotational speed of said turbine by adjusting the pitch of said blades with respect to said airstream;

first sensing means for sensing a rotational speed proportional to a speed of said apparatus and generating a first input signal proportional to said speed;

second sensing means for sensing a parameter of said electrical output of said air driven generator and generating a second input signal proportional to said parameter;

control means for receiving said first and second input signals and generating;

a first control signal applied to said blade pitch actuator means for controlling an output frequency of said electrical output of said air driven generator by controlling said blade pitch and turbine; and

a second control signal applied to said air driven generator for controlling an output voltage of said electrical output of said air driven generator;

whereby said electric motor is started in a soft-start manner and drives said apparatus when supplied with said electrical output of said air driven generator.

12. In an aircraft having an engine for propelling said aircraft in flight along a flight path, an electric starter motor operably attached to said engine for driving said engine, and an air driven generator for extracting energy from a flow of air past said aircraft while it is in flight and converting said energy into electrical power, a method for starting said engine while said aircraft is in flight, said method comprising the steps of:

a) electrically connecting said air driven generator to supply alternating current (AC) electrical power to said starter motor for driving said engine;

b) accelerating said engine to a predetermined start-speed;

c) supplying fuel and a source of ignition to said engine while said starter motor is driving said engine at said start-speed.