Method and system for controlling an emergency device

Abstract

The invention relates to a method for controlling an emergency device of a helicopter, said helicopter comprising a rotor suitable for being rotated, said emergency device being suitable for supplying additional emergency propulsion power to the helicopter, in said method comprising a step (10) of measuring the rotation speed of the helicopter rotor, a step (12) of calculating the drift of the measured rotation speed, a step (20) of continuously verifying conditions such that the speed of rotation of the rotor is higher than a predetermined value, referred to as arming speed, and the drift of the rotation speed is lower than a predetermined value, referred to as arming drift, and a step (22) of activating the emergency device if the verified conditions are validated.

Claims

1. A control method for an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter, said method comprising the following steps: a step of measuring the rotation speed of the helicopter rotor, a step of calculating the derivative of the measured rotation speed, a step of detecting a drop in the rotation speed of the rotor at an instant t0 below the nominal rotation speed V.sub.NRnom of the helicopter rotor, a step of activating a timer to measure the duration Δt from the instant t0, the timer being activated as long as the rotation speed of the rotor is dropping, a step of measuring at an instant t0+Δt the rotation speed of the rotor V.sub.NR, a step of continuously verifying the following conditions: the rotation speed of the rotor is greater than a predetermined value, called arming speed, the derivative of the rotation speed is greater than a predetermined value, called arming derivative, the derivative of the rotation speed at instant t0+Δt is lower than or equal to: $\frac{V_{\mathrm{DEC}}-V_{\mathrm{NR}}}{\Delta t}$ the derivative of the rotation speed at instant t0+Δt is greater than or equal to: $\frac{V_{\mathrm{DEC}}-V_{\mathrm{NRnom}}}{\Delta t}$ with V.sub.DEC being the stall speed of the helicopter rotor, below which the helicopter is in stall due to the loss of lift of the helicopter, an activation step of the emergency device if the verified conditions are validated.

2. The control method according to claim 1, wherein the verification step verifies the following additional condition: the derivative of the rotation speed is greater than a predetermined value, called disarming derivative.

3. A control system for an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter, said control system comprising: an input adapted to receive a measurement of the rotation speed of the helicopter rotor, calculation means adapted to carry out the control method according to claim 1, an ignition output configured to transmit an activation order to the control device if the verified conditions are validated by said control process.

4. The control system according to claim 3, further comprising a supply input adapted to transmit electrical energy which allows the calculation means to operate and to transmit the activation order to the control device.

5. The control system according to claim 3, further comprising a status output, adapted to transmit information relative to the operating status of the control system.

6. The control system according to claim 3, further comprising a plurality of inputs adapted to receive information from the helicopter sensors and/or information from the emergency device sensors.

7. A helicopter comprising said emergency device according to claim 3.

8. A control method for an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter, said method comprising the following steps: a step of measuring the rotation speed of the helicopter rotor, a step of calculating the derivative of the measured rotation speed, a step of detecting a drop in the rotation speed of the rotor at an instant t0 below the nominal rotation speed VNRnom of the helicopter rotor, a step of activating a timer to measure the duration Δt from the instant t0, the timer being activated as long as the rotation speed of the rotor is dropping, a step of measuring at an instant t0+Δt the rotation speed of the rotor VNR, a step of continuously verifying the following conditions: the rotation speed of the rotor is greater than a predetermined value, called arming speed, the derivative of the rotation speed is greater than a predetermined value, called arming derivative, the derivative of the rotation speed at instant t0+Δt is lower than or equal to: $\frac{V_{\mathrm{DEC}}-V_{\mathrm{NR}}}{\mathrm{dt}}$ the derivative of the rotation speed at instant t0+Δt is greater than or equal to: $\frac{V_{\mathrm{DEC}}-V_{\mathrm{NRnom}}}{\Delta t}$ with VDEC being the stall speed of the helicopter rotor, below which the helicopter is in stall due to the loss of lift of the helicopter, an activation step of the emergency device if all the verified conditions are validated.

Description

5. LIST OF FIGURES

(1) Other objects, characteristics and advantages of the invention will become apparent upon reading the following description given solely by way of a non-limiting example and with reference to the appended figures, wherein:

(2) FIG. 1 is a schematic view of a control method according to an embodiment of the invention

(3) FIG. 2 is a schematic view of a control system according to a first embodiment of the invention,

(4) FIG. 3 is a schematic view of a control system according to a second embodiment of the invention,

(5) FIG. 4 is a schematic view of a graph representing the activation zone of the emergency device controlled by a control method according to an embodiment of the invention, depending on the rotation speed of the rotor and the derivative of the rotation speed of the rotor.

6. DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

(6) The following embodiments are examples. Even though the description refers to one or several embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply to a single embodiment. Simple characteristics of different embodiments may also be combined to form other embodiments. In the figures, scale and proportions are not strictly respected for purposes of illustration and of clarity.

(7) FIG. 1 represents schematically a control method according to an embodiment of the invention, controlling an emergency device of a helicopter, said helicopter comprising a rotor adapted to be rotated, said emergency device being adapted to supply additional emergency propulsive power to the helicopter.

(8) The control method 100 comprises a first step 10 of measuring the rotation speed of the helicopter rotor. The control process 100 then comprises a second step 12 for calculating the derivative of the measured rotation speed, in order to detect in particular a possible drop in the rotation speed. In this embodiment, the control method 100 further comprises additional steps, in particular a step 14 of detecting a drop in the rotation speed of the rotor at an instant t0 below a nominal rotation speed V.sub.NRnom of the helicopter rotor, a step 16 of starting a timer measuring the duration Δt from the instant t0, the timer being activated as long as the rotation speed of the rotor is dropping, and a step 18 of measuring at an instant t0+Δt the rotation speed V.sub.NR of the rotor.

(9) The control method 100 then comprises a step 20 of continuously verifying several conditions, described in greater detail further on with reference to FIG. 4. Finally, if all the verified conditions are validated, the control method 100 comprises a step 22 of activating the emergency device.

(10) FIG. 2 schematically shows a control system 200 according to a first embodiment of the invention, adapted to carry out a control method according to the embodiment presented in FIG. 1.

(11) The control system 200 comprises calculation means 24, adapted to carry out the control method, which may consist of, for example, of a calculator, an integrated or non-integrated electronic circuit, etc. The calculation means 24 is connected to an input 26 adapted to receive the measurement of the rotation speed of the helicopter rotor and an output 28 for ignition, configured to transmit an activation order to the control device if the verified conditions are validated by the said control method.

(12) In addition, in this first embodiment, the control system comprises a supply input 30 adapted to transmit electrical energy allowing the operation of the calculation means and the transmission of the activation order to the control device and a status output 32, adapted to transmit information relating to the operating status of the control system.

(13) In a second embodiment, the control system 300 comprises additional inputs connected to the calculation means 24′, in particular inputs coming from the helicopter sensors, for example: an input 34 supplying the ambient temperature, an input 36 supplying the ambient pressure,

(14) or inputs supplying information coming from the emergency device sensors, for example: an input 38 supplying the temperature of a block of propellant of the emergency device an input 40 supplying the rotation speed of the emergency device backup turbine.

(15) The system 24′ according to this second embodiment may further comprise an output 42 for controlling a solenoid valve for testing the emergency device as described in application FR3026435 A1 of the applicant.

(16) FIG. 4 schematically shows a diagram 400 representing the activation zone 44 of the emergency control device by a control method according to an embodiment of the invention, depending on the rotation speed of the rotor and the derivative of the rotation speed of the rotor.

(17) The activation zone 44 corresponds to a zone in which all the conditions verified at the verification step are validated. In particular, the conditions verified at the verification step defining an activation zone 44 represented by a white background surrounded by an inhibition zone 46 represented by a hatched background. The borders between the zones are defined by the following conditions verified by the control method: the rotation speed V.sub.NR of the rotor is greater than a predetermined value, called arming speed V.sub.arme, the derivative dV.sub.NR/dt of the rotation speed is lower than a predetermined value, called arming derivative (dV.sub.NR/dt).sub.arme, the derivative of the rotation speed dV.sub.NR/dt is greater than a predetermined value, called disarming speed derivative (dV.sub.NR/dt).sub.desarme, as represented by the two oblique lines, the derivative of the rotation speed dV.sub.NR/dt at instant t0+Δt is lower than or equal to:

(18) $\frac{V_{\mathrm{DEC}}-V_{\mathrm{NR}}}{\Delta t}$ the derivative of the rotation speed at instant t0+Δt is greater than or equal to:

(19) $\frac{V_{\mathrm{DEC}}-V_{\mathrm{NRnom}}}{\Delta t}$

(20) with V.sub.DEC being the stall speed of the helicopter rotor, below which the helicopter is in stall due to the loss of lift of the helicopter.

(21) The two last conditions vary as a function of time measured by the timer, and are shown in FIG. 4 by: two continuous lines for a first time Δt.sub.1 measured by the timer (the activation zones represented correspond to this first measured time), two dotted lines for a second time Δt.sub.e measured by the timer (in this representation, the zones of activation and inhibition are different from those represented and are delimited by dotted lines).

(22) For Δt=0, the line is vertical as the point (V.sub.DEC−V.sub.NRnom)/Δt is at infinity.