# US 12,215,636 B2 · Pulse modulation technique for gas turbine engines

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- Number: US 12,215,636 B2
- Document ID: US12215636B2
- Status: Granted
- Kind: B2
- Application number: 17/942,529
- Filed: 2022-09-12
- Published: 2024-03-14
- Granted: 2025-02-04
- Earliest claimed: 2022-09-12
- Assignees: Textron Innovations Inc.
- Applicants: Textron Innovations Inc.
- Inventors: Joshua Andrew Emrich; Thomas Dewey Parsons
- Web page: https://patentgrep.com/patent/US12215636B2

## CPC

- F02C 9/32: characterised by throttling of fuel (F02C9/38 takes precedence)
- B64D 31/00: Power plant control systems; Arrangement of power plant control systems in aircraft
- B64D 31/06: actuated automatically
- B64D 45/00: Aircraft indicators or protectors not otherwise provided for
- F02C 9/28: Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence)
- F02C 9/42: specially adapted for the control of two or more plants simultaneously
- B64C 27/04: Helicopters
- B64D 2045/0085: {Devices for aircraft health monitoring, e.g. monitoring flutter or vibration}
- F05D 2220/323: for aircraft propulsion, e.g. jet engines
- F05D 2220/329: in helicopters
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64C: AEROPLANES; HELICOPTERS
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

Various implementations described herein are related to an aircraft having a multi-engine configuration with multiple engines. The aircraft may have a flight control system coupled to the multiple engines with a multi-engine interface. The flight control system may be configured to reduce fuel consumption of at least one engine of the multiple engines during reduced-engine operation by pulse modulating fuel delivery to the at least one engine of the multiple engines.

## Claims

### Claim 1

An aircraft comprising:
a multi-engine configuration with multiple engines; and
a flight control system coupled to the multiple engines with a multi-engine interface, wherein the flight control system is configured to:
reduce fuel consumption of at least one engine of the multiple engines during reduced-engine operation by pulse modulating fuel delivery to the at least one engine of the multiple engines;
calculate a minimum altitude of the aircraft for reduced-engine operation; and
restart the at least one engine if a current altitude of the aircraft drops below the minimum altitude.

### Claim 2 (depends on 1)

The aircraft of claim 1, wherein:
during the reduced-engine operation, the flight control system is configured to adjust operation of the at least one engine of the multiple engines by throttling the at least one engine to IDLE or sub-IDLE.

### Claim 3 (depends on 2)

The aircraft of claim 2, wherein:
the flight control system is configured to maintain IDLE or sub-IDLE via oscillating fuel flow to the at least one engine during the reduced-engine operation.

### Claim 4 (depends on 3)

The aircraft of claim 3, wherein:
by maintaining an IDLE or sub-IDLE operation condition, the at least one engine has a reduced time required to produce and contribute additional engine power available.

### Claim 5 (depends on 1)

The aircraft of claim 1, wherein:
the flight control system is configured to selectively reduce engine power to at least one other engine of the multiple engines based on input from a pilot, and
the flight control system is configured to provide visual indication of the at least one other engine selectively operating with reduced engine power by the pilot.

### Claim 6 (depends on 5)

The aircraft of claim 5, wherein:
upon selective reduction in engine power to at least one other engine by the pilot or by automated means, the flight control system is configured to adjust operation of the at least one other engine of the multiple engines by throttling the at least one other engine to IDLE, sub-IDLE, or completely OFF.

### Claim 7 (depends on 5)

The aircraft of claim 5, wherein the flight control system is configured to selectively reduce engine power of the at least one other engine of the multiple engines by continuously calculating altitude for the reduced-engine operation based on an aircraft descent rate of the at least one other engine.

### Claim 8 (depends on 7)

The aircraft of claim 7, wherein:
the aircraft descent rate is based on current ambient conditions related to the altitude including outside ambient temperature during autorotation of the aircraft with the at least one engine of the multiple engines operating with reduced engine power.

### Claim 9 (depends on 1)

The aircraft of claim 1, wherein:
the aircraft comprises a rotorcraft, and
the multiple engines comprise multiple turbo-shaft engines.

### Claim 10

A method comprising:
interfacing with multiple engines in an aircraft, the aircraft having a multiple engine configuration;
continuously calculating a minimum altitude of the aircraft for reduced-engine operation;
reducing fuel consumption of at least one engine of the multiple engines by pulse modulating fuel delivery to the at least one engine of the multiple engines during the reduced-engine operation; and
restarting the at least one engine if a current altitude of the aircraft drops below the minimum altitude.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
during reduced-engine operation, adjusting operation of the at least one engine of the multiple engines by throttling the at least one engine to IDLE or sub-IDLE.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
maintaining IDLE or sub-IDLE via oscillating fuel flow to the at least one engine during the reduced-engine operation,
wherein, by maintaining an IDLE or sub-IDLE operation condition, the at least one engine has a faster engine restart time.

### Claim 13 (depends on 10)

The method of claim 10, further comprising:
increasing fuel delivery to the at least one engine and providing corresponding advisory messages to a pilot if altitude drops significantly while in reduced-engine operation during flight.

### Claim 14 (depends on 1)

The aircraft of claim 1, wherein the flight control system is configured to calculate the minimum altitude for reduced-engine operation based on a descent rate of the aircraft and an engine restart time of the at least one engine.

### Claim 15 (depends on 10)

The method of claim 10, wherein calculating the minimum altitude for reduced-engine operation is based on a descent rate of the aircraft and an engine restart time of the at least one engine.