Control apparatus for a variable section nozzle of an aircraft

The present invention relates to a control device for a variable-section nozzle of an aircraft.

To reduce fuel consumption, some aircraft have a motor with a variable area nozzle. Thus, it is possible to adjust the flow through the nozzle, by changing its section, to external conditions and engine operating conditions to optimize the performance of the engine.

According to one embodiment illustrated in <figref idrefs="f0001">figure 1</figref>A propulsion unit of an aircraft comprises a nacelle 10 in which is disposed substantially concentrically an engine 12 connected by means of a mast to the rest of the aircraft.

The nacelle 10 includes an inner wall defining a conduit 14 with an air inlet 16 at the front, a first portion of the incoming air flow, called primary flow, passing through the power plant 12 to participate in the combustion, the second portion of the air flow, called secondary flow, being driven by a blower 18 and flowing in an annular conduit 20 defined by the inner wall of the nacelle and the outside wall of the power. At the rear, the primary stream escapes through a stationary nozzle 22 with a tapered portion whose diameter is reduced as the flow direction of the flow. The secondary flow escapes through an outlet 24 delimited inside by the fixed nozzle 22 and on the outside by a mobile nozzle 26 corresponding to the nozzle of variable section 26 provided at the rear end of the nacelle.

According to one embodiment, the nozzle of variable section 26 may be translated along a direction of movement parallel to the longitudinal direction of the engine (corresponding to the engine axis referenced 28) between two extreme positions corresponding to a first forward position illustrated in strong line on <figref idrefs="f0001">figure 1</figref> and a rear position shown in dashed lines in <figref idrefs="f0001">figure 1</figref>. Insofar as the fixed nozzle has a frustoconical shape, it is possible to control the outlet section of the variable section nozzle by adjusting the position of the latter according to the direction of travel.

According to one embodiment illustrated in <figref idrefs="f0002">2</figref>, The nozzle of variable section 26 includes movable portions 30 that move through a mechanical transmission chain 32 driven by a motor 34. The mechanical transmission chain 32 transforms the rotational movement of the motor output shaft 34 in a translational movement along the direction of movement of the moving parts.

The invention relates more particularly to a nozzle of variable section which is not subject to ice accretion, such as that described in document <patcit id="pcit0001" dnum="US3797785A"><text>US-3,797,785</text></patcit>.

On the <figref idrefs="f0002">2</figref>There is illustrated a control device of a nozzle of variable section according to the prior art.

To control the moving parts position, the command string includes a control system 42 of the engine called FADEC (for Full Authority Digital Engine Control), and 44 control body called PE (for Power Electronics) ensuring the engine control 34.

Thus, when the control system 42 transmits a signal to the control member 44, the latter impels a rotation motor 34 which through the mechanical transmission chain 32 generates the translation of the movable part 30. The member 44 control ensures among others the power converter function between a control circuit upstream and downstream power circuit.

To meet the constraints imposed by the certification authorities, the controller uses redundancy means to improve the reliability failure to Steering to improve the reliability of the components themselves. Thus, the control device comprises two motors 34 and 34 ', each being capable of generating the movement of all the movable parts 30, two control members 44 and 44', one for each engine and two power supplies 46 and 46 'for supplying electric power to the supervisory bodies and associated engines.

To ensure the transmission of signals between the supervisory bodies and the regulation system 42 within the constraints of segregation, there are four sets of cables, two for each control member 44, 44 '. This solution allows to respect the constraints imposed by the certification authorities.

If a control body fails, the other can ensure the control of motors and thus controlling the position of the moving parts of the variable area nozzle.

If a power supply fails, the second power supply can be replaced. Each supervisory body, if a series of cables fails, communication between the control system and the control member may be provided by the second set of cables.

Finally, if one engine fails, the movement of the movable portions of the movable section nozzle may be provided by the second motor.

Although it is satisfactory in terms of safety and reliability, this controller is not fully satisfactory because of the doubling of certain elements which leads to increasing the onboard weight and complexity to the operation and integration.

An alternative could be to opt for a simple type of architecture, including but a monitoring body for each variable area nozzle. However, this architecture does not meet current standards for reliability of control of the thrust of the engine.

In the field of variable area nozzles, the document is known <patcit id="pcit0002" dnum="GB588502A"><text>GB-588 502</text></patcit>. This document describes a nozzle of variable section with moving parts whose motion is controlled by a kinematic chain which comprises a motor, a shaft connected to the motor, a cable connected to the moving parts and a mechanism for coupling / uncoupling the rod and the cable . This mechanism is controlled by a solenoid. When the solenoid is deactivated, the mechanism ensures the coupling of the rod and the cable so that the moving parts move according to the rotation of the motor. When the solenoid is energized, the mechanism no longer ensures the coupling of the rod and the cable so that the movement of the moving parts is free. In this case, it is impossible to determine the exact position of the moving parts and adjust the thrust of the engine. Therefore, this simplistic architecture does not meet current standards for reliability of control of the thrust of the engine.

The present invention aims to remedy the drawbacks of the prior art.

To this end, the invention relates to a control device according to the characterizing part of claim 1 a variable-section nozzle for an engine of an aircraft, said nozzle of variable section comprising one or more movable parts to to modify the section of the nozzle and connected via a mechanical transmission chain to an actuator, said device comprising the actuator control system connected to a control member capable of controlling the actuator. This architecture helps reduce onboard weight and simplifies the integration and operation. In addition, the resulting device meets current standards of reliability control the thrust of the engine.

Other characteristics and advantages appear from the following description of the invention, description is given by way of example only, with reference to the accompanying drawings in which:<ul><li>The <figref idrefs="f0001">figure 1</figref> is a side view of a propulsion unit of an aircraft with partly cut away to schematically show a variable area nozzle,</li><li>The <figref idrefs="f0002">2</figref> is a schematic representation of a control architecture for a variable-section nozzle according to the prior art, and</li><li>The <figref idrefs="f0003">3</figref> is a schematic representation of a control architecture of a variable area nozzle of the invention.</li></ul>

A nozzle of variable section comprises at least one movable portion 56 connected via a mechanical transmission chain 60 to an actuator 58 such as a motor, as schematically illustrated in <figref idrefs="f0003">3</figref>.

The engine, the variable area nozzle, or the mobile paries 56, mechanical transmission chain and the actuator 58 are not described more as they are known in the art.

By way of example only, the nozzle of variable section and the mechanical transmission chain may be identical to those disclosed in <patcit id="pcit0003" dnum="EP779429A"><text>EP-779 429</text></patcit>.

For controlling the variable section nozzle, the aircraft comprises a control system 62 of the engine also called FADEC 64 and a control member also called PE for controlling an actuator 58. As for the prior art, '64 control member ensures the converter function between a control circuit upstream and a downstream power circuit.

According to the invention, for each nozzle of variable section, the aircraft comprises a single control member 64. In a first variant, the aircraft comprises, for each nozzle of variable section a single actuator 58 adapted to move through a kinematic chain all the movable parts of the variable area nozzle, said actuator being controlled by the single control member 64. According to another variant, the aircraft comprises, for each nozzle of variable section, a plurality of actuators 58, each of which is connected to moving parts through channels of mechanical transmission, all of the actuators for moving the moving parts of a nozzle of variable section and being controlled by a single control member 64. Although the transmission chain is more complex in the case of a single actuator, this solution will be preferred because it reduces onboard weight and simplify operation and integration.

According to one embodiment, an actuator 58 is in the form of an electric motor whose output shaft is connected to a first end of the mechanical transmission chain, the other end, or more precisely the other ends of the latter being each connected to a movable part. The aircraft includes for each control body 64 two sets of wires 66, 66 'for the transmission of signals between the control system 62 and the control member 64 and two power supplies 68, 68' into electrical energy. By the standards of certification, loss of control of the variable section of the nozzle is either due to the failure of the actuator 58 (or actuators) or failure of the control body 64 due a break in the power supply or an internal malfunction.

According to one characteristic of the method and of the inventive control device, the aircraft comprises, for each nozzle of variable section immobilization means 70 of the moving parts 56 that are activated permanently and which are deactivated only when the system control 62 controls the change of position or of the movable parts 56. as long as the displacement of the movable portions 56 of a nozzle of variable section is not controlled by the control system 62 (via the control member 64), the securing means block 70 or 56 moving parts.

The immobilization means 70 are likely to have two states, a first activated state in which they interfere with the mechanical transmission chain and prevent any movement or moving parts 56 and a second disabled state in which they do not interfere not with the transmission chain and allow the movement of the moving parts or 56. Thus, when the fastening means 70 are in the activated state, the nozzle of variable section functions as a nozzle with a constant section that then when immobilization means 70 are in the disabled state it functions as an actual nozzle of variable section whose section can be adjusted.

Preferably, the immobilizing means comprise a body and a movable part capable of being in contact with an element of the mechanical transmission chain to the activated state and said remote part of the mechanical transmission chain to the deactivated state and a biasing means (like a spring for instance) able to maintain the movable part in the activated state and a suitable actuator in response to a signal to maintain the movable part in the deactivated state against the return means.

Thus, at rest, in the absence of signal, the immobilization means are activated.

Among the possible solutions to ensure the function of securing means, which will be chosen should have a reliability of less than 10^E-6. To meet this criterion, the actuator means of immobilization is an electromagnet.

According to one embodiment, the securing means 70 are in the form of a disc brake comprising firstly a bracket with two jaws which clamp an element of the transmission chain, and secondly at least a spring tending to maintain the jaws close together and at least one electromagnet which, when activated, removes the jaws against the spring.

Thus, when the electromagnet is not carrying a current, it exerts no effort so that the jaws under the action of the spring holding the immobilized mechanical transmission chain.

In a first embodiment, the immobilization means 70 are controlled by the control member 64 and a link is provided between the fastening means 70 and the control member 64. This variant is particularly suitable when the actuator 58 is a DC motor. In this case, when the control member 64 supplies current to the motor for moving the active parts 56, it also supplies in parallel or in series electromagnet immobilizing means which then pass to the deactivated state. According to a first advantage, when the control body fails due to a cut-off the power supply or an internal malfunction, no signal is transmitted to the immobilization means 70 remaining and the state activated.

Alternatively, the immobilization means 70 could be controlled by the control system 62 and a connection could be provided between the fastening means 70 and the control system 62. In this case, when the latter transmits an electrical signal to the monitoring body to cause movement of the movable parts or 56, it transmits a signal in parallel to the immobilization means to disable them.

In addition to the fastening members, the aircraft comprises for each nozzle means 72 for determining the actual position of the or moving parts connected to the control system 62. Thus, these means 72 are independent of the control member and of the actuator and can inform the control system 62 even in the event of failure of one of these elements.

Preferably, the means 72 to determine the actual position of the moving parts or include incremental angular sensor type RVDT (for <i>Rotary Variable Differential Transformer).</i>

This sensor may be installed at the actuator, in the mechanical transmission chain or at the one or more moving parts.

In normal operation, before each change of configuration, the means 72 inform the control system 62 and it indicates the actual position of the one or more movable parts of the variable section nozzle.

In following, the control system 62 transmits a signal to the control member 64 so that it triggers the rotation of the motor 58 in a certain angular value. In parallel, an instruction is transmitted to the immobilization means 70 to turn off. Upon receiving the signal, the control 64 controlling body rotation of the motor 58 according to the given angular value which itself causes via the mechanical coupling movement of the or the movable portions of the variable section nozzle. This movement is made possible by the fact that the immobilizing means are disabled. After a lapse of time, the immobilizing means are again activated. This time frame can be generated by a timer.

Advantageously, the means 72 indicate to the control system 62 the new or actual position of the movable parts 56 of the variable area nozzle after each configuration change. This feedback is used to indicate to the control system 62 if the monitoring body and / or the actuator 58 are failing. Indeed, if the actual position detected by the means 72 and transmitted to the control system 62, after changing the configuration of the variable section nozzle, does not correspond to the theoretical value calculated by the control system 62 then this translated a failure of one of the elements.

Even in this circumstance, the thrust control is perfectly mastered the fact that the immobilizing means 70 prevent modification of the section which is maintained at a known value given by the means 72 by the control system 62.

For example, three configurations are examined to show that the driver is always able to control the thrust of the engine in case of failure of the actuator and / or supervisory body.

The first scenario is a blockage of the nozzle in the open position. In this case, the thrust will not be adapted to the cruising phase. The increase in engine speed can recover the lack of push through higher fuel consumption. If you can not recover enough thrust while cruising altitude will be lowered. Fuel-consumption is estimated in the order of 5% in this case.

The second scenario is a blockage in the closed position. In this situation, the nozzle has a configuration adapted for the cruise phase.

Insofar before take-off nozzle must be set in the open position if the driver detects the lock in the closed position during checks before take-off, it will either cancel the flight or manually force in the open position with the using a ground engineer.

If this anomaly occurs during the flight, in case of overshoot, engine power will be reduced to avoid the risk of vibration. However, the aircraft is dimensioned to make a go-around with one engine.

The latter case is blocking middle position. The engine thrust will not be adapted to the cruise phase, or the take-off phase. However, the section of the nozzle is well known the control system 62 by the means 72.

If this error occurs before takeoff, as before, the driver can either cancel the flight or manually force in the open position with the help of a mechanic to the ground.

If the plane is cruising phase, the engine speed will be increased but less than in the case of a full opening.

If the plane is in the descent phase, the engine speed will be reduced to avoid vibration but less than for normal operation.

A thrust according to the control method of an engine of an aircraft according to the invention, the means 72 indicate to the control system 62 the actual position of the or movable parts 56, and the control system 62 controls the thrust of the actuator taking into account the actual position of the movable parts 56 or the variable area nozzle.