METHOD OF STOPPING A ROTORCRAFT ENGINE IN OVERSPEED, AND A SYSTEM AND A ROTORCRAFT ASSOCIATED THEREWITH

• US 20160090918A1
• Filed: 09/28/2015
• Published: 03/31/2016
• Est. Priority Date: 09/26/2014
• Status: Active Grant

• Current Assignee: Airbus Helicopters
• Original Assignee: Airbus Helicopters
• Inventors: CERTAIN, Bernard
• Granted Patent: US 10,047,678 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F01D 21/00 Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: F01D 21/02 Shutting-down responsive to overspeed
• CPC Class Codes: F01D 21/04 responsive to undesired position of rotor relative to stator or to breaking-off of a part of the rotor, e.g. indicating such position
• CPC Class Codes: F01D 21/06 Shutting-down
• CPC Class Codes: F01D 21/14 responsive to other specific conditions
• CPC Class Codes: F02C 3/04 having a turbine driving a compressor power transmission arrangements F02C7/36; control of working fluid flow F02C9/16
• CPC Class Codes: F02C 3/10 with another turbine driving an output shaft but not driving the compressor
• CPC Class Codes: F02C 7/22 Fuel supply systems
• CPC Class Codes: F02C 9/26 Control of fuel supply F02C9/48 takes precedence; fuel valves F02C7/232
• CPC Class Codes: 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
• CPC Class Codes: F02C 9/46 Emergency fuel control
• CPC Class Codes: F05D 2220/323 for aircraft propulsion, e.g. jet engines
• CPC Class Codes: F05D 2220/329 in helicopters
• CPC Class Codes: F05D 2270/021 to prevent overspeed
• CPC Class Codes: F05D 2270/09 to cope with emergencies
• CPC Class Codes: F05D 2270/091 in particular sudden load loss
• CPC Class Codes: F05D 2270/093 of one engine in a multi-engine system
• CPC Class Codes: F05D 2270/304 Spool rotational speed
• CPC Class Codes: F05D 2270/331 Mechanical loads
• CPC Class Codes: F05D 2270/335 : Output power or torque

Abstract

A method of stopping an engine of a rotorcraft in overspeed, the engine comprising a gas generator and a power assembly. When the engine is in operation, the engine is automatically stopped when the following three conditions are satisfied simultaneously: a torque (Tq) measured on the power assembly is below a predetermined torque threshold (Tq1); and a speed of rotation referred to as a “first speed of rotation (N1)” of the gas generator is above a threshold referred to as a “first speed threshold (S1)”; and a speed of rotation referred to as a “second speed of rotation (N2)” of the power assembly is above a threshold referred to as a “second speed threshold (S2)”.

Claims

1. A method of stopping an engine of a rotorcraft in overspeed, the rotorcraft including at least one engine, the engine comprising a gas generator and a power assembly, the power assembly having at least one power turbine set in rotation by gas coming from the gas generator, the power assembly having at least one power shaft constrained to rotate with the power turbine;

wherein when the engine is in operation, the engine is automatically stopped when the following three conditions are satisfied simultaneously;

a torque (Tq) measured on the power assembly is below a predetermined torque threshold (Tq1); and

a speed of rotation of the gas generator, referred to as a “

first speed of rotation (N1)”

, is above a threshold referred to as a “

first speed threshold (S1)”

; and

a speed of rotation of the power assembly, referred to as a “

second speed of rotation (N2)”

, is above a threshold referred to as a “

second speed threshold (S2)”

.

2. A method according to claim 1, wherein the gas generator is fed by a fuel-metering device, the metering device is suitable for being set between a minimum limit inducing a minimum fuel flow rate and a maximum limit inducing a maximum fuel flow rate, and the engine is stopped automatically by setting the fuel-metering device of the engine at its minimum limit.

3. A method according to claim 1, wherein at least one engine includes a cock on a fuel pipe, and the engine is automatically shut down by closing the cock.

4. A method according to claim 1, wherein each engine is fed with fuel by at least one pump, and the pump is shut down when the three conditions are satisfied simultaneously.

5. A method according to claim 1, wherein the torque (Tq) is measured by arranging a torque measuring system on the power shaft.

6. An overspeed safety system for an engine of a rotorcraft, the engine comprising a gas generator and a power assembly, the power assembly having at least one power turbine set in rotation by the gas generator, the power assembly having at least one power shaft constrained to rotate with the power turbine, the overspeed safety system including a shutdown system for stopping operation of the engine, the overspeed safety system comprising a processor unit connected to the shutdown system;

wherein the overspeed safety system comprises a speed sensor referred to as a “

first speed sensor”

for measuring a speed of rotation of the gas generator, referred to as a “

first speed of rotation”

, the overspeed safety system including a speed sensor referred to as a “

second speed sensor”

for measuring a speed of rotation of the power assembly, referred to as a “

second speed of rotation (N2)”

, the overspeed safety system comprising a torque measuring system for measuring torque (Tq) transmitted by the power assembly, the processor unit being connected to the first speed sensor as well as to the second speed sensor and to the torque measuring system, and being configured to implement the method according to claim 1, by stopping the engine automatically when the following three conditions are satisfied simultaneously;

a torque (Tq) measured on the power assembly is below a predetermined torque threshold (Tq1); and

a speed of rotation referred to as a “

first speed of rotation (N1)”

of the gas generator is above a threshold referred to as a “

first speed threshold (S1)”

; and

a speed of rotation referred to as a “

second speed of rotation (N2)”

of the power assembly is above a threshold referred to as a “

second speed threshold (S2)”

.

7. An overspeed safety system according to claim 6, wherein the shutdown system comprises a fuel-metering device conveying fuel to the gas generator.

8. An overspeed safety system according to claim 6, wherein the shutdown system comprises at least one pump conveying fuel to the gas generator.

9. An overspeed safety system according to claim 6, wherein the overspeed safety system includes a shield ring surrounding the power turbine, the power turbine comprising a plurality of blades, each blade being fastened to a fuse member.

10. An overspeed safety system according to claim 6, wherein the processor unit is a FADEC of the engine.

11. A rotorcraft comprising at least one rotor, the rotorcraft including at least one engine, the engine driving a power transmission train connected to the rotor;

wherein the rotorcraft includes at least one overspeed safety system according to claim 6, each overspeed safety system being connected to an engine.