Aeronautics and astronautics – Aircraft control – Pilot operated
Reexamination Certificate
1998-01-07
2001-03-27
Poon, Peter M. (Department: 3644)
Aeronautics and astronautics
Aircraft control
Pilot operated
C244S226000, C244S227000, C244S228000
Reexamination Certificate
active
06206329
ABSTRACT:
DESCRIPTION
1. Technical Field of the Invention
The present invention relates to a process and a device for the control of a control surface of an aircraft.
The invention more particularly relates to an electric control device intended for transport aircraft simultaneously satisfying the requirements of precision, reliability and lightness existing for such equipment.
2. Prior Art
FIG. 1
diagrammatically illustrates a known control device of the type presently equipping AIRBUS aircraft A320 and A340. This device comprises an arrangement of three actuators
10
,
12
,
14
for operating a rudder
16
. The three actuators are of the hydromechanical type and each has a mechanical control input
18
,
20
,
22
. Their control is ensured by a linkage
24
, which acts on mechanical control inputs
18
,
20
,
22
and which can be operated from pedals
26
(rudder bar). In addition, each actuator
10
,
12
,
14
is supplied by a different hydraulic circuit
28
,
30
,
32
supplying the energy necessary for the movement of the rudder
16
.
The control device also incorporates a computing or calculating unit
27
able to develop control orders, instructions or commands such as e.g. yaw damping commands. These commands are added to the control commands from the pedals
26
by means of a system of electro-hydraulic jacks
36
. The addition of the control commands from the computing unit to those from the pedals takes place mechanically and in such a way that the movements of the jacks
36
are not retransmitted to the pedals.
A device
40
for giving an artificial sensation of force is provided for restoring to the pedals a force which is a function of their deflection, thereby facilitating control. This device
40
incorporates a so-called trim actuator
42
controlled by the computing unit
27
, so that the positioning of the rudder
16
in a predetermined position known as the zero force position when the pedals
26
are released by the pilot.
Devices
44
and
46
controlled by the computing unit
27
serve to limit the movement of the pedals and/or the rudder.
With a control device according to
FIG. 1
, the three actuators
10
,
12
and
14
are simultaneously pressurized from hydraulic circuits
28
,
30
,
32
and the actuators are controlled in parallel for manipulating the rudder
16
.
As indicated hereinbefore, the electro-hydraulic jacks
36
exert control commands and in particular yaw damping commands by means of a mechanical linkage in order to control the mechanical input of the actuators. Thus, friction and any deformation of the mechanical transmission system unfavourably influences the precision of the controls.
A second known type of rudder control device makes it possible to overcome this disadvantage by using three electrical input-equipped actuators. Electric control signals are directly applied to the input of the actuators. Thus, in the absence of a mechanical control transmission system, it is possible to operate the rudder with a significantly increased precision. However, such a device has no mechanical backup in the case of an electric fault leading to the failure of all the controls.
Document (1) FR-A-2 603 865 describes an aircraft rudder control device equipped with two electro-hydraulic actuators with an electrical input and a hydromechanical actuator with a mechanical input. In this device, each actuator is supplied by its own hydraulic circuit. The electro-hydraulic actuators receive electric control commands supplied by computers associated therewith.
Moreover, only one of the three actuators is operated at once in order to manipulate the rudder. According to a predetermined hierarchy, in the case of a failure of the control system of one of the actuators, the control system of the next priority actuator is initiated. The control system with the hydromechanical actuator has the lowest triggering or initiating priority. It therefore constitutes a mechanical backup in the case of an electric failure to the other control systems.
In the known rudder control devices, the pressurizing pumps of the hydraulic circuit supplying the actuator are driven or supplied with energy by the aircraft engines. For safety reasons, the pumps of the hydraulic circuits of the different actuators are driven by at least one engine. In general, one of the hydraulic circuits can be driven by at least two engines.
A failure or stoppage of one of the engines can lead to a pressure loss in the hydraulic circuit associated therewith and consequently the corresponding actuator is rendered inoperative.
The failure of one of the engines, particularly in the case where the aircraft has its engines fixed to the wings, can lead not only to a pressure loss in the hydraulic circuit associated therewith, but more particularly leads to a thrust unbalance, the thrust no longer being symmetrical. This unbalance can be compensated by manipulating the rudder in an appropriate manner.
When the rudder control device has three actuators with an electric input or three actuators with a mechanical input controlled in parallel, the manipulation of the rudder and consequently the balancing of the equipment remain possible by operating the two actuators not affected by the pressure drop of the hydraulic circuit associated with the faulty engine.
With a device according to document (1), in the case of a failure of an engine leading to a pressure drop in a hydraulic circuit of an electro-hydraulic actuator, the manipulation of the rudder takes place either with the electro-hydraulic actuator remaining in the operating state, or optionally with the hydromechanical actuator.
However, when it is necessary to compensate a thrust unbalance of the engines, particularly in the take-off phase, maximum loads are exerted on the rudder and said loads condition the size of the actuators to be used.
Thus, as it is not possible to simultaneously operate the rudder with a hydromechanical actuator and an electro-hydraulic actuator on equipment equipped with a rudder control device according to document (1), the actuators and associated hydraulic circuits must be dimensioned in such a way that each actuator is able to exert on the rudder the maximum forces or loads necessary for compensating an asymmetrical thrust in the case of a failure of one of the engines.
Such a measure leads to an increase in the size and consequently the weight of the actuators and the corresponding hydraulic circuits.
The aforementioned problem not only arises for the rudder, but also for the other control surfaces of the aircraft. The other control surfaces of an aircraft such as the inclination or pitch control surfaces (elevators) are certainly less sensitive than the rudder to thrust instability resulting from an engine failure, but can also be subject to occasional high loads.
The control surfaceS of an aircraft are exposed to high loads, particularly in the case of turbulence or when the aircraft performs a manoeuvre such as e.g. a vertical acceleration, a turn or a pull-out.
An aircraft state in which the control surfaces are subject to such loads is designated hereinafter by the term << manoeuvre state >>.
Thus, in order to cope with a << manoeuvre state >>, the actuators must also be overdimensioned.
Thus, one object of the invention is to propose an aircraft control surface control device, which has a reduced weight compared with the device of document (1) and which permits the manipulation of the rudder or the other control surfaces even in the case of engine failure leading to an aircraft thrust unbalance, or in case of a << manoeuvre state >>.
Another object is to propose a device remaining operational even in the case of a failure of the electric servocontrol systems.
Another object of the invention is to propose a control device permitting the manipulation of the control surfaces with a significantly increased precision compared with mechanical control-based devices.
A further object of the invention is to propose an improved control process for the control surfaces satisfying severe reliabil
Gautier Jean-Pierre
Ortega Jean-Marc
Burns Doane Swecker & Mathis L.L.P.
Dinh Tien
Poon Peter M.
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