Method for stopping an engine in overspeed, and associated system and rotorcraft

Patent metadata

Field	Value
Publication number	US-11485485-B2
Application number	US-202117230054-A
Country	US
Kind code	B2
Filing date	Apr 14, 2021
Priority date	Jun 17, 2020
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A method for stopping an engine of a rotorcraft in overspeed, the rotorcraft comprising at least one engine, the engine comprising a gas generator and a power assembly, the power assembly comprising at least one power turbine rotated by gases originating from the gas generator, the power assembly comprising at least one power shaft rotationally secured to the power turbine, the power assembly rotating about a longitudinal axis at a speed referred to as the “speed of rotation”. The method comprises steps consisting in measuring a current value of the speed of rotation, determining a time derivative of the current value of the speed of rotation, referred to as the “current derivative(d⁢⁢N⁢⁢2⁢⁢id⁢t)”,and automatically stopping the engine when the current derivative(d⁢⁢N⁢⁢2⁢⁢id⁢t)changes sign.

First claim

What is claimed is:

1. A method for stopping an engine of a rotorcraft in overspeed, the rotorcraft comprising at least one engine, the engine comprising a gas generator and a power assembly, the power assembly comprising at least one power turbine rotated by gases originating from the gas generator, the power assembly comprising at least one power shaft rotationally secured to the power turbine, the power assembly rotating about a longitudinal axis at a speed of rotation (N2);
wherein, during a flight, the method comprises:
measuring a current value (N2i) of the speed of rotation reached by the power assembly during a predetermined time period (T);
determining a current derivative

(

dN
⁢
2
⁢
i

dt

)

by determining a time derivative of the current value of the speed of rotation; and
automatically stopping the engine when the current derivative

(

dN
⁢
2
⁢
i

dt

)

changes sign over the predetermined time period (T) from a strictly negative value to a strictly positive value.

2. The method according to claim 1
wherein the stopping step is implemented when the current derivative

(

dN
⁢
2
⁢
i

dt

)

is less than or equal to a first predetermined threshold value (S1) during a first intermediate time period (T1) and the current derivative

(

dN
⁢
2
⁢
i

dt

)

is then greater than or equal to a second predetermined threshold value (S2) during a second intermediate time period (T2).

3. The method according to claim 2
wherein the current derivative

(

dN
⁢
2
⁢
i

dt

)

being expressed as a percentage of the current value N2i per second (% N2i·s −1 ), the first predetermined threshold value S1 is between −50% N2i·s −1 and −100% N2i·s −1 .

4. The method according to claim 2
wherein the current derivative

(

dN
⁢
2
⁢
i

dt

)

is expressed as a percentage of the current value (N2i) per second (% N2i·s −1 ), the second predetermined threshold value (S2) is between +50% N2i·s −1 and +200% N2i·s −1 .

5. The method according to claim 2 wherein the first intermediate time period (T1) is less than 1 second.

6. The method according to claim 2
wherein the second intermediate time period (T2) is less than 1 second.

7. The method according to claim 1
wherein the gas generator comprises a rotating assembly that rotates about the longitudinal axis at a speed of rotation (N1) of the rotating assembly, the method comprises a step comprising measuring a current value (N1i) of the speed of rotation (N1) reached by the gas generator.

8. The method according to claim 7
wherein the stopping step is conditioned by a current value (N1i) of the speed of rotation (N1) greater than a third predetermined threshold value (S3).

9. The method according to claim 1
wherein the method includes a step comprising measuring a current value (Tqi) of an engine torque (Tq) transmitted to the at least one power shaft.

10. The method according to claim 9
wherein the stopping step is conditioned by a current value (Tqi) of the engine torque (Tq) greater than a fourth predetermined threshold value (S4).

11. The method according to claim 1
wherein the method comprises a step of processing the current derivative

(

dN
⁢
2
⁢
i

dt

)

,

the processing step enabling filtering the current derivative

(

dN
⁢
2
⁢
i

dt

)

and/or calculating an average value of the current derivative

(

dN
⁢
2
⁢
i

dt

)

.

12. An overspeed safety system for an engine of a rotorcraft, the engine comprising a gas generator and a power assembly, the power assembly comprising at least one power turbine rotated by gases originating from the gas generator, the power assembly comprising at least one power shaft rotationally secured to the power turbine, the power assembly rotating about a longitudinal axis at a speed of rotation (N2), the overspeed safety system comprising:
a speed sensor for measuring a current value (N2i) of the speed of rotation (N2) reached by the power assembly during a predetermined time period T;
a shut-down system for stopping operation of the engine; and
a processing unit connected to both the speed sensor and the shutdown system,
wherein the processing unit is configured to implement a method comprising:
measuring a current value (N2i) of the speed of rotation reached by the power assembly during a predetermined time period (T);
determining a current derivative

(

dN
⁢
2
⁢
i

dt

)

by determining a time derivative of the current value of the speed of rotation; and
automatically stopping the engine when the current deriv

Assignees

• Airbus Helicopters

Inventors

• Dumur Guillaume
• Gaulmin Francois-Xavier

Classifications

• F05D2270/021

  to prevent overspeed · CPC title

• F05D2260/90

  Braking · CPC title

• F02C9/46

  Emergency fuel control · CPC title

• F01D21/02 Primary

  Shutting-down responsive to overspeed · CPC title

• B64C27/006 Primary

  Safety devices · CPC title