Regulation system for controlling the vibratory behavior and/or the twisting stability of a drivetrain, a rotorcraft fitted with such a regulation system, and an associated regulation method

Patent metadata

Field	Value
Publication number	US-10730613-B2
Application number	US-201816007473-A
Country	US
Kind code	B2
Filing date	Jun 13, 2018
Priority date	Jun 13, 2017
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

A regulation system for controlling the vibratory behavior in twisting and/or the twisting stability of a drivetrain of a rotorcraft, the regulation system comprising two regulation loops that are interleaved one in the other, the two regulation loops being arranged “in cascade” relative to each other to regulate firstly a first speed of rotation NG of a gas generator of at least one turboshaft engine driving said drivetrain in rotation, and secondly a second speed of rotation NTL of a free turbine of the engine(s).

First claim

What is claimed is:

1. A regulation system for controlling vibratory behavior in twisting and/or twisting stability of a drivetrain of a rotorcraft, the regulation system comprising two regulation loops that are interleaved one another, the regulation loops being arranged in cascade relative to each other to regulate firstly a first speed of rotation NG of a gas generator of at least one turboshaft engine driving the drivetrain in rotation, and secondly a second speed of rotation NTL of a free turbine of the turboshaft engines(s), the regulation system comprising at least:
a fuel metering member controlled by a control device, the control device responding to a fuel flow rate setpoint (Set) to generate a metering command (Met) for fuel that is to be injected into the turboshaft engine(s);
first measurement means for measuring a first measured speed of rotation (NG measured ) of the gas generator of the turboshaft engine(s);
a first comparator for generating a first difference (ε NG ) of a first regulation loop, the first difference (ε NG ) being generated by comparing a first setpoint (NG set ) for the first speed of rotation with the first measured speed of rotation (NG measured )
a first corrector for correcting the first difference (ε NG ) and for generating the fuel flow rate setpoint (Set);
second measurement means for measuring a second measured speed of rotation (NTL measured ) of the free turbine of the engine(s);
a filter for filtering the second measured speed of rotation (NTL measured ) and for generating a filtered signal (NTL filtered );
a second comparator for generating a second difference (ε NTL ) of a second regulation loop, the second difference (ε NTL ) being generated by comparing a second setpoint (NTL set ) for the second speed of rotation with the filtered signal (NTL filtered ); and
a second corrector for correcting the second difference (ε NTL ) and for generating the first setpoint (NG set ) for the first speed of rotation;
wherein the filter is of adaptive type, the regulation system including computation means for determining filter coefficients of the filter, the filter coefficients being variable and associated with the filter in recursive manner by the computation means for controlling the vibratory behavior in twisting and/or the twisting stability of the drivetrain of the rotorcraft,
wherein the filter is a band-stop type filter in order to stop a frequency band including a frequency of a first resonant mode in twisting of the drivetrain, and
wherein the filter is a second order filter, the filter being defined by a transfer function of the following form:

NTLfiltered
NTLmeasured

=

(

1
+

2
×
Z
⁢

⁢
1
⁢
p

W
⁢

⁢
1
⁢
p

×
p

+

1

W
⁢

⁢
1
⁢

p
2

×

p
2

)

(

1
+

2
×
Z
⁢

⁢
2
⁢
p

W
⁢

⁢
2
⁢
p

×
p

+

1

W
⁢

⁢
2
⁢

p
2

×

p
2

)

where NTL measured is the second speed of rotation measured by the second measurement means, NTL filtered is the filtered signal generated by the filter from the second speed of rotation NTL measured , W1p, W2p, Z1p, and Z2p correspond to the filter coefficients.

2. The system according to claim 1 , wherein the regulation system includes a first memory for storing at least two distinct sets of predetermined values for the filter coefficients (W1p, W2p, Z1p, Z2p), the computation means determining a first set (E 1 ) for application to the filter when the second measured speed of rotation (NTL measured ) lies in a first range [a,b[, a second set (E 2 ) for applying to the filter when the second measured speed of rotation (NTL measured ) lies in a second range [b,c[, and an n th set (En) for applying to the filter when the second measured speed of rotation (NTL measured ) lies in an n th range [x1,x].

3. The system according to claim 1 , wherein the system includes an accelerometer for measuring vibration to which the rotorcraft is subjected, a measurement member for measuring frequency of rotation (f rot ) of a main rotor of the rotorcraft, and a second memory for storing at least one threshold value for a vibration amplitude, the computation means acting, when the measured amplitude of the vibration is greater than the threshold value(s) for a predetermined duration, in order to modify the filter coefficients so that the frequency band stopped by the filter (F 2 ) includes the frequency of rotation (f rot ) of the main rotor.

4. The system according to claim 1 , wherein the second corrector implements

Assignees

• Airbus Helicopters

Inventors

• Leonard Anthony

Classifications

• B64D35/02

  specially adapted for specific power plants · CPC title

• B64D31/06

  actuated automatically · CPC title

• F05D2270/807

  Accelerometers · CPC title

• F02C9/56

  with power transmission control · CPC title

• F05D2270/334

  Vibration measurements · CPC title