WO2014091294A1

WO2014091294A1 - Mechanism for closing aircraft doors

Info

Publication number: WO2014091294A1
Application number: PCT/IB2013/002760
Authority: WO
Inventors: Alberto Maria ZUCCARI
Original assignee: QFP s.r.l.
Priority date: 2012-12-14
Filing date: 2013-12-13
Publication date: 2014-06-19
Also published as: ITRM20120642A1

Abstract

A mechanism for closing aircraft doors, comprising a plurality of attachment devices (2, 3) positioned along a closing line, wherein each attachment device (2, 3) comprises at least one retaining element (2a, 3a), fixable to the fuselage (5) of an aircraft and having a concavity defining a housing seat (4), and a closing pin (2b, 3b) applicable to a door (100) of an aircraft and engageable inside the housing seat (4) for locking the door (100) relative to the fuselage (200). The retaining element (2a, 3a) is fixed and the closing pin (2b, 3b) is rotatable about an axis (X) and has a transversal cross-section which is not axially symmetric relative to the axis (X) in such a way that the closing pin (2b, 3b) is rotatable between a locked position, in which it engages the housing seat (4) and interferes with the retaining element (2a, 3a) for locking the door (100) closed, and a released position in which it disengages the housing seat (4) and does not interfere with the retaining element (2a, 3a) to allow the opening of the door (100).

Description

MECHANISM FOR CLOSING AIRCRAFT DOORS

DESCRITION

FIELD OF THE INVENTION

This invention relates to a closing mechanism for aircraft doors, preferably (but not limited to) cargo doors.

In particular, this invention relates to a closing mechanism which can be conveniently applied to doors opening on the outside and subject to pressurization loads. The closing mechanism of the present invention is suitable for transferring structural loads between the door and the fuselage. STATE OF THE ART

It is known that aircraft doors, both for boarding and disembarking passengers and cargo doors, are hinged on one side of the fuselage and present, on one or more of the free sides, dedicated closing mechanisms to firmly keep the door in closed position.

Known closing mechanisms are described, for example, in documents US4473201 , US4758030, US5823473, and US2010219647.

Currently, a constant research for weight reduction in aircrafts has led to a widespread introduction of composite materials. Such materials, unlike metals, do not withstand correctly high concentrated loads.

Now, owing to closing mechanisms' design and weight, between door and fuselage it is possible to insert only a limited number of attachment devices, which can therefore only define a limited number of closing points between door and fuselage. For this reason, each attachment device has to bear high concentrated loads, which for the above-mentioned reasons, does not suit the application on composite material doors. In other words, traditional closing mechanisms do not combine the need for an effective closing action with the need for a reduction of the masses.

According to the above, the aim of the present invention is to make available a closing mechanism for aircraft doors which enables an effective closing action between door and fuselage, in particular a distributed action, while minimizing at the same time the masses involved.

Such aim is achieved by the closing mechanism for aircraft doors according to the present invention, which is characterized by the features described in the claims. The technical features of the invention, according to the above- mentioned aim, are evident in the following claims, and the advantages will be clear in the following detailed description, with reference to the accompanying figures, which only represent an illustrative and not limitative embodiment of the invention, in which:

BRIEF DESCRIPTION OF THE FIGURES

- figure 1 shows a closing mechanism according to the present invention;

- figure 1A shows an enlargement of a detail of the mechanism shown in figure 1 ;

- figure 2 shows a first part of the mechanism pictured in figure 1 , cross- sectioned in a first position;

- figure 2A shows a lateral view of the cross-sectioned part of figure 2;

- figure 3 shows a second part of the mechanism pictured in figure 1 , cross-sectioned in a second position;

- figure 3A shows a lateral view of the cross-sectioned part of figure 3;

- figures 4 and 5 show views of figures 2A and 3A in a mechanism configuration applied to an aircraft door in a position suitable for opening;

- figures 6-7 and 8-9 show changed views of figures 2A and 3A in two different closing positions, respectively;

- figures 7a and 9a show enlargements of the same detail of figures 7 and 9;

- figure 10 show a schematization of the cross-sectional view of figure 3A in closing position in order to highlight the centre of the profiles. According to the attached figures, 1 represents globally a mechanism for closing aircraft doors (the door, indicated by 100, is shown in figures 4 and 5, where 200 stands for the fuselage or a fixed part of mechanism 1 , which shall be fixed firmly to the fuselage). In a known manner, door 100 is of the type installed in an opening of the fuselage of the aircraft and is of the kind suitable to contain the internal pressurization of the aircraft. As can be seen in figure 1 , mechanism 1 includes a series of attachment devices 2, 3 lined along a closing straight line so as to distribute closing forces between door 100 and fuselage 200 along the full length of one closing side of door 100.

DETAILED DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE PRESENT INVENTION

Alternatively, attachment devices 2 and 3 may be placed along a generic closing line, which is not necessarily straight but may rather be curve or tapered or anyway inclined. Attachment devices 2 and 3 may also be placed along respective staggered closing lines, whose envelope defines, for instance, the closure of a tapered profile.

In particular, mechanism 1 comprises two types of attachment devices, which will be indicated as first attachment device 2 and second attachment device 3, and they will be described in detail further on. More in detail, wherein each attachment device 2, 3 comprises at least one retaining element 2a, 3a fixed to the fuselage (200) and having a concavity defining a housing seat 4 and a respective closing pin 2b, 3b mounted on a side of the door 100 and engageable within housing seat 4 to carry out the closing of door 100 with respect to fuselage 200.

The concave shape of retaining element 2a, 3a enables it to present an extremity portion 2c, 3c to retain the respective pin 2b, 3b, determining a lock in closing door 100.

Conveniently, each closing pin 2b, 3b can be rotated around an axis "X", fixed with respect to door 100, and has a transversal cross-section which is not axially symmetric relative to the axis "X" in such a way that closing pin 2b, 3b is rotatable between a locked position (figure 6-7, 8-9), in which it engages the respective housing seat 4 and interferes with the respective retaining element 2a, 3a to lock door 100 closed, and a released position (figures 2A, 3A) in which it disengages the housing seat 4 and does not interfere with the retaining element 2a, 3a to enable the opening of door 100. In other words, each closing pin 2b, 3b offers to its respective retaining element 2a, 3a a variable transversal cross-section (that is to say of the "cam" type) according to the angular position taken by pin 2b, 3b around axis "X" so that in correspondence with minimum dimensions, pin 2b, 3b may overcome the portion of extremity 2c, 3c of each retaining element 2a, 3a whereas in correspondence with maximum dimensions, pin 2b, 3b reaches into housing seat 4 so much that pin 2b, 3b ends up stuck on one side of the retaining element 2a, 3a, in particular on the side defining housing seat 4. Preferably, rotation axis "X" is common to all pins 2b, 3b and is parallel to the mentioned closing line.

Moreover, pins 2b, 3b of the attachment device 2, 3 are strictly interconnected to rotate simultaneously around axis "X" and are preferably constituted by portions of one single spindle "A". Preferably, spindle "A" is rotatingly supported in correspondence with its own cylinder portions located between pins 2, 3. In other words, spindle "A" presents an alternate sequence of pins 2, 3 and cylinder portions, the latter aiming at supporting rotatingly the spindle in its rotation around axis "X".

Rotation of pins 2b, 3b (or of spindle "A" in case of such choice) is carried out hydraulically or electrically or even manually, for example by means of a lever operated by a handle through transmission systems.

In the showed embodiment (figure 1 ), a closing mechanism 1 is shown and it has fifteen attachment devices 2, 3, placed in an alternate fashion so as to include three first attachment devices 2 and twelve second attachment devices 3, in an alternate fashion so as to have a first attachment device 2 between two sets of three second attachment devices 3. In-between the fifteen pins 2b, 3b of the fifteen attachment devices 2, 3 there are fourteen cylinder portions rotatingly supported by dedicated supports (not pictured in the figures attached for clarity reasons).

Figures 2 and 2A show in detail the first attachment device 2 in opening position.

The first attachment device 2 is aimed at carrying out a gravity closure of door 100 and thus identifies a simple support for the respective closing pin 2b on retaining element 2a. In other words, the stopping action caused by the retaining element 2a of the first attachment device 2 is tangential to the hinge axis "Z" of door 100 (shown in figure 4 in which a curve arrow shows the opening direction by gravity of door 100). Such situation occurs in a first phase of closure of door 100, when there is no pressurization inside the aircraft yet.

Retaining element 2a of the first attachment device 2 defines a supporting surface 2d, mainly flat, while corresponding pin 2d presents an external engagement surface, preferably curve or with a flat part, designed to abut by resting against the supporting surface (2d) in the locked position.

Figures 3 and 3A show in detail the second attachment device 3 in opening position.

The second attachment device 3 aims at carrying out a clamping action along a direction mainly tangent to the external surface of door 100. Such "traction" action of the door, tangential along the fuselage 200 (thus transversal with respect to the action carried out by the first attachment devices 2) is performed during the pressurization of the inside of the aircraft as such pressurization tends to determine, on the thin sides of fuselage 200, an expansion increasing their external form and thus puts them in traction.

More in detail, retaining element 3a of the second attachment device 3 defines a curve supporting surface 5 having a first curvature radius R1 whereas the corresponding closing pin 3b has an external curve engagement surface 6 having a second curvature radius R2, preferably different from the first curvature radius R1 and designed to abut by resting against the curve supporting surface 5 in the locked position.

In light of the above, each first attachment device 2 is set up so as to define a first contact area between pin 2b and its respective retaining element 2a, whereas each second attachment device 3 is set up so as to define a second contact area between pin 3b and it respective retaining element 3a, in which the two contact areas are placed angularly with respect to rotating axis "X" and identify respective tangent planes "P1", "P2" (perpendicular to contact forces "F" exchanged between pin and retaining element) at an angle to each other.

More in detail, respective tangent planes "Ρ , "P2" are at an a angle to each other.

Preferably, at least one attachment device 2, 3 (more preferably each one of them) is set up so as to define, in locking position, a contact force "F" between pin 2b, 3b and retaining element 2a, 3a, eccentric with respect to rotation axis "X" and such as to generate on pins 2b, 3b a rotating moment, equiverse to rotation from the unlocking position to locking position. In other words, such eccentric action stabilizes the attachment, thus closing, action as force "F" creates a moment in the locking direction.

Figure 10 shows in detail the geometry of the contact starting in second attachment device 3, in which contact force "F" is shown, directed along an action straight line passing by axis "Y" of the external engagement surface 6 of pin 3b and by axis "W" of the curve supporting surface of the retaining element 3a. Such action line presents and eccentricity value "e" with respect to rotation axis "X".

Even though it is not explicitly shown in the figures, such eccentricity is preferably included also in the coupling geometry between pin 2b and retaining element 2a in the first attachment device 2. Preferably, stopping elements are included (not explicitly pictured), active on each closing pin 2b, 3b (or on spindle "A" according to the technical design) to limit a maximum rotation of closing pin 2b, 3b around axis "X" when reaching locking position. In functioning, during a closing phase of door 100, initially there is a movement of door 100 around hinge axis "Z" to take the door in an angular position fit for closing. Such position, obtained by means of known handling machines (e.g. hydraulic cylinders) is enabled by the initial positioning of attachment devices 2,3 placed in opening position (figures 2A, 3A).

When door 100 reaches the angular position fit for closing, pins 2 and 3 are put in rotation around axis X to take them to closing position.

In this situation (figures 6-7 and 7A), pin 2b of the first attachment device 2 is located on the supporting surface 2d of the respective retaining element 2a. If, for any reason, the door could not reach the correct closing position, the rotation of pin 2b (by virtue of its cam shape and the contact with surface 2d of retaining element 2a) can provide on the whole door, within a range of 10.0 mm from the supposed closing position, a "pull in" function of the fuselage, so as to take the door in the closing position.

Such configuration, though, still identifies a detachment between pin 3b and retaining element 3a in the second attachment device 3. As can be seen in figure 7A, the external curve engagement surface 6 of pin 3b is detached by the corresponding support surface 5 by the retaining element in a "g" quantity, defining a gap only filled later during pressurization of the aircraft. Conveniently, pin 3b of the second attachment device 3 (and preferably each pin 2b, 3b or spindle A according to such an embodiment) is mobile when getting closer or farther from its respective retaining element 3a, when the rotation of pin 3b is locked.

During the pressurization of the aircraft, due to deformations, the diameter of the fuselage tends to increase, up until reducing gap "g" to zero, taking pin 3b in contact with its respective retaining element 3a. Such approach/distancing is assisted by pin 2b of the first attachment device 2 sliding on the supporting surface 2d of the respective retaining element 2a so as to go along with the deformation of the fuselage during pressurization and depressurization.

At a certain level of pressurization there will be a simultaneous support of all pins 2b, 3b on their respective retaining elements 2a, 3a. Above such level of pressurization, preferably only pins 3b will be supported by their respective retaining elements 3a.

The closing pin 2b, 3b of each attachment device 2, 3 has, in cross-section (perpendicular to axis "X"), an external convex profile (i.e. without any corners or cavities) at least in the portion which will be involved in the support against its corresponding retaining element 2a, 3a. Such convex profile (or portion of profile) defines a cam which can be moved into opening or closing position after rotation around axis "X".

In an embodiment not shown here, at least one of the attachment devices 2, 3, preferably each of them, includes a couple of retaining elements 2a, 3a (analogous to what was described above in the shown embodiment, thus each with a curved shape defining its respective housing seat) and one single closing pin which can be used in both housing seat to define a first and a second contact area, respectively, with retaining elements. The two retaining elements are placed in different angular positions with respect to rotation axis "X" of the pin so that the first and second contact area define respective tangent plans at an angle to each other. The geometry of contact areas and their placement around axis "X", as well as eccentricity "e" of contact forces and gap "g" can be completely identical to those described above with reference to the shown embodiment. In other words, in this last configuration the two different types of attachment device 2, 3 are included in one single locking device, whose rotating pin has, on the outside, both external engagement surfaces, abutted against the corresponding supporting surfaces of each of the two retaining elements.

Moreover, in this configuration the closing pin of each attachment device has preferably, in cross section (perpendicular to axis "X"), an external convex profile (i.e. without any corners or cavities) at least in the portions which will be involved in the support against the corresponding retaining elements.

Such convex profile (or profile portions) defines a couple of cams which can be moved into opening or closing position after rotation around axis "X".

Moreover, in a further not shown possible embodiment, it is possible to fix retaining elements to the door and apply rotating closing pins on the fuselage.

Preferably, in all possible embodiments, retaining elements 2a, 3a can be regulated (though steadily fixed) to enable different door closing geometries. The present invention satisfies the intended goals, overcoming inconvenience reported for known techniques.

The mechanism of the present invention allows for a noteworthy reduction of masses and a distribution of attachment devices along the closing line, so as to reduce stress on composite material constituting fuselage and door and, moreover, on the single attachment devices themselves (which can thus have a smaller size, and thus weight).

Claims

1. A mechanism for closing aircraft doors, comprising a plurality of attachment devices (2, 3) positioned along a closing line, wherein each attachment device (2, 3) comprises:

- at least one retaining element (2a, 3a), fixable to the fuselage

(200) of an aircraft and having a concavity defining a housing seat (4);

- a closing pin (2b, 3b) applicable to a door (100) of an aircraft and engageable inside the housing seat (4) for locking the door (100) relative to the fuselage (200), characterised in that the retaining element (2a, 3a) is fixed and that the closing pin (2b, 3b) is rotatable about an axis (X) and has a transversal cross-section which is not axially symmetric relative to the axis (X) in such a way that the closing pin (2b, 3b) is rotatable between a locked position, in which it engages the housing seat (4) and interferes with the retaining element (2a, 3a) for locking the door (100) closed, and a released position in which it disengages the housing seat (4) and does not interfere with the retaining element (2a, 3a) to allow opening of the door (100).

2. The mechanism according to claim 1 , wherein the closing pins (2b, 3b) of each attachment devices (2, 3) are rigidly connected to each other for simultaneously rotating about the rotation axis (X).

3. The mechanism according to claim 1 or 2, wherein the closing pin (2b, 3b) of each attachment device (2, 3) presents, in transversal cross-section, an external convex profile defining a cam in at least a portion aimed at engaging by resting on the corresponding retaining element (2a, 3a).

4. The closing mechanism according to any one of the preceding claims, wherein at least a first (2) of the attachment devices (2, 3) defines a first closure suitable for an absence of pressurisation and it is designed in such a way as to define a first area of contact between the respective closing pin (2b) and the respective retaining element (2a), and wherein at least a second (3) of the attachment devices (2, 3) defines a second closure suitable for a presence of pressurisation and it is designed in such a way as to define a second area of contact between the respective pin (3b) and the respective retaining element (3a), the first and second areas of contact being positioned in different angular positions relative to the axis of rotation

(X) and defining respective tangential planes (P1 , P2) inclined at an angle to each other.

5. The closing mechanism according to claim 4, wherein the retaining element (2a) of the first attachment device (2) defines a substantially flat supporting surface (2d) and wherein the closing pin (2b) of the first attachment device (2) has an outer engagement surface designed to abut by resting against the supporting surface (2d) in the locked position.

6. The closing mechanism according to claim 4 or 5, wherein the retaining element (3a) of the second attachment device (3) defines a curved supporting surface (5) having a first radius of curvature (R1) and wherein the closing pin (3b) of the second attachment device (3) has a curved outer engagement surface (6) having a second radius of curvature (R1 ) different from the first radius of curvature (R1 ) and designed to abut by resting against the curved supporting surface (5) in the locked position.

7. The closing mechanism according to claim 6 when it depends on claim 5, wherein the closing pin (3b) of the second attachment device (3) is movable towards and away from the corresponding retaining element (3a), with rotation of the pin locked, by sliding the closing pin (2b) of the first attachment device (2) on the respective retaining element (2a) to follow a deformation of the fuselage (200) during pressurising and depressurising.

8. The closing mechanism according to any one of claims 4 to 7, wherein at least one of the first and second attachment devices (2, 3) is designed in such a way as to define, in the locked position, a contact force (F) between the closing pin (2b, 3b) and the retaining element (2a, 3a) which is eccentric relative to the axis of rotation (X) and such as to generate a moment of rotation equal and opposite to the rotation of the closing pin (2b, 3b) from the unlocked position to the locked position.

9. The closing mechanism according to any one of the preceding claims 1 to 4, wherein at least one of the attachment devices (2, 3), preferably each of them, comprises a pair of retaining elements (2a, 3a), each having a concavity defining a respective housing seat (4), and a single closing pin designed in such a way as to engage inside the housing seats (4) in a closed position for defining respectively a first and a second area of contact with the retaining elements (2a, 3a), the two retaining elements (2a, 3a) being positioned in different angular positions relative to the axis of rotation (X) in such a way that the first and second areas of contact define respective tangential planes (P1 , P2) inclined at an angle to each other.

10. The closing mechanism according to any one of the preceding claims, also comprising stop means acting on each closing pin (2b, 3b) for limiting a maximum rotation of the closing pin (2b, 3b) about the rotation axis (X).

11. An aircraft comprising a fuselage (200), at least one opening made on the fuselage (200), a door (100) hinged to the fuselage (200) and positioned for closing the opening, and a closing mechanism (1 ) according to any one of the preceding claims, operatively interposed between the fuselage (200) and the door (100).

12. The aircraft according to claim 11 , wherein the closing mechanism (1) has the retaining elements (2a, 3a) fixed stably to the fuselage (200) and the closing pins (2b, 3b) rotatably mounted on a side of the door (100) with the axis of rotation (X) of the closing pins (2b, 3b) located in a fixed position relative to the door (100).

13. The aircraft according to claim 11 when it depends on claim 4, wherein the first attachment device (2) rests the respective closing pin (2b) by gravity on the corresponding retaining element (2a) under the action of the weight of the door (100), and wherein the second attachment device (3) clamps the respective closing pin (3b) on the corresponding retaining element (3a) along a direction substantially tangential to an outer profile of the fuselage (200) at the second attachment device (3).