Aeronautics and astronautics – Aircraft power plants – Mounting
Reexamination Certificate
1999-01-26
2001-01-16
Poon, Peter M. (Department: 3641)
Aeronautics and astronautics
Aircraft power plants
Mounting
C248S554000, C060S039300
Reexamination Certificate
active
06173919
ABSTRACT:
TECHNOLOGICAL FIELD
The invention relates to a device for attaching an aircraft engine onto a pylon fixed to an aircraft structure such as a wing or an element of the fuselage.
More precisely, the invention relates to an attachment device responsible for taking up, for example, lateral and vertical forces and/or the engine torque. Such an attachment device constitutes one of the elements of an attachment system through which the forces generated by the engine are transmitted to the aircraft through the pylon.
STATE OF THE TECHNOLOGY
In a known way, engines which are fitted to aircraft are suspended from or laterally attached to a pylon which is itself fixed respectively under the wing or onto the fuselage of the aircraft.
The attachment systems that link the engines to the pylon are generally constituted by at least two or three separate attachment devices. One of these devices is responsible, for example, for taking up the lateral and vertical forces generated by the engine, in order to transmit them to the aircraft through the pylon. More often than not, this attachment device also provides the transmission of the engine torque. However this transmission can also occur through a separate attachment device.
In a known and systematic manner, the attachment device that provides the taking up of the lateral and vertical forces, and more often than not, the engine torque, has a structure of the type illustrated in
FIG. 1
of the appended drawings.
In this Figure, reference number
1
designates the pylon onto which the engine must be attached. The attachment device comprises essentially a fitting
3
, and from two to four connecting arms (two connecting arms
4
and
5
are illustrated in FIG.
1
). The fitting
3
is fixed onto the pylon
1
by two pairs of tensile bolts
6
and
7
, screwed into barrel nuts
8
and
9
, themselves housed in bores which pass through the fitting
3
.
Furthermore, the connecting arms
4
and
5
provide the link between the fitting
3
and the engine
2
. To this effect, each connecting arm is connected to the fitting
3
by one or two pins and to the engine
2
by one pin. Hence, in the case of
FIG. 1
, the connecting arm
4
is connected to the fitting
3
by two pins
10
and
11
situated on either side of the bore into which the barrel nuts
8
are received, while the connecting arm
5
is connected to the fitting
3
by a single pin
12
, offset circumferentially towards the outside with respect to the bore within which the barrel nuts are received. The pins connecting respectively the connecting arms
4
and
5
to the engine
2
are designated by reference numbers
13
and
14
.
Existing attachment devices produced in accordance with this principle are illustrated notably through documents U.S. Pat. No. 5,620,154 and U.S. Pat. No. 5,649,417.
The attachment devices of this type, which are fitted to practically all aeroplanes sold at the present time, do not allow one to resolve the problems generated by the recent appearance of new improved engines with higher performance.
The continuous research seeking an increase in thrust is leading to the appearance of engines with air intakes of larger and larger diameters. When the engines are attached under the wings of aircraft, it is desirable to be able to raise them so as to prevent them touching the ground.
With existing attachment devices of the type previously described making reference to
FIG. 1
, this requires the raising up of connecting arms
4
and
5
, that is to say bringing them closer to the horizontal. Given that the fixing points of the connecting arms to the engine cannot be moved, this leads either to the hinge pins
10
and
12
coming closer to the bores within which the barrel nuts are received or contrary to this to an increase in the circumferential length of the fitting
3
, so as to offset the hinge pins on the connecting arms towards the outside with respect to the hinge pins
13
and
14
of the connecting arms on the engine.
If the first solution is adopted, this would amount to reducing the existing spacing between the bores in which the barrel nuts
8
and
9
are received and the bores in which the hinge pins
10
and
12
are received. This solution cannot be considered in practice since it would lead to an intolerable reduction in the spacing between the bores. In effect, the reduction of this spacing would bring about a risk of fracture of the fitting that had become too thin in the relevant area.
The other solution, which consists of increasing the circumferential length of the fitting
3
, is no longer applicable in practice, for aerodynamic reasons. In effect, the presence of the fitting
3
creates turbulence which disturbs the air-flow and brings about a loss of thrust. An increase in the circumferential length of the fitting therefore leads to an unacceptable increase in turbulence. On the contrary, it is desirable to reduce turbulence by reducing the distance between pins
10
and
12
through which the connecting arms
4
and
5
are articulated on the fitting
3
.
Therefore, existing attachment devices in practice prevent the integration of engines of modern design having increased thrust.
DESCRIPTION OF THE INVENTION
The precise object of the invention is an attachment device for an aircraft engine, the original design of which allows one to envisage the integration of engines with greater thrust, without increasing aerodynamic disturbance created by the device and while preserving its mechanical strength properties.
According to the invention, this result is achieved by means of a device for attaching an engine onto a pylon fixed to an aircraft structure, that comprises an intermediate fitting capable of being fixed to the pylon by bolts screwed into barrel nuts housed in bores that pass through the fitting and at least two connecting arms hinged on the fitting by pins, in such a way as to connect the fitting to the engine, characterised by the fact that at least one of said pins is mounted in one of the bores housing the barrel nuts.
According to one preferred embodiment of the invention, two barrel nuts are housed respectively in two sections of each bore situated on either side of a groove which passes through one of the connecting arms, in such a way that said pin is mounted at least in parts of said sections that are adjacent the groove.
This preferred embodiment of the invention can take different forms, depending on the relative diameters of the barrel nuts and the pivot pins.
Thus, when the diameter of the pin is less than that of the barrel nuts and of the bore, the pin is mounted in the previously mentioned sections of the bore using two rings, that may have shoulders or may not. The two barrel nuts are then housed in each of the sections of the bore, beyond the ends of the pin.
When the two barrel nuts have a diameter less than that of the pin and of the bore, they can be received in housings machined in end portions of the pin, these end portions then being mounted in the previously mentioned sections of the bore.
When the two barrel nuts have a diameter less than that of the pin and of the bore, they can also be mounted in the previously mentioned sections of the bore, beyond the ends of the pin using two rings, that may have shoulders or may not.
In the case where the two barrel nuts have a diameter equal to that of the pin, they can be mounted directly in the previously mentioned sections of the bore beyond the ends of the pin.
In the same case, the two barrel nuts and the pin can also be produced as a single component of uniform diameter.
Finally still with the pin and the two barrel nuts having the same diameter, two nut carriers and the pin can be produced as a single component of uniform diameter, the floating nuts then being mounted in the nut carriers.
Whatever the embodiment of the invention, the intermediate fitting is in general capable of being fixed to the pylon by four bolts, screwed into four barrel nuts housed two by two in two bores passing through end regions of the fitting. Preferably, two hinge pins for the two conne
Aerospatiale - Societe Nationale Industrielle
Burns Doane Swecker & Mathis L.L.P.
Dinh Tien
Poon Peter M.
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