Hinged door for aircraft landing gear

The door comprises a panel (14) formed from two rigid parts (14a, 14b) hinged to each other edge to edge. A first part (14a) of these two parts is connected to the aircraft structure through a pivot pin (20) and a control means (22) is inserted between this first part (14a) and the structure. A kinematic control mechanism (16) connects the two parts (14a, 14b) to the aircraft structure, so as to enable progressive and controlled folding of these parts when opening the door. Thus the landing gear door can be opened and closed without any risk of it coming into contact with the wheels when the landing gear is extended.

TECHNICAL DOMAIN

The invention relates to an aircraft landing gear door.

The door according to the invention may be used to close a landing gear compartment that contains landing gear on any type of aircraft, particularly when the landing gear is located under the aircraft fuselage.

STATE OF THE ART

A landing gear door is typically formed by a one-piece rigid panel hinged onto the aircraft structure by a pivot pin offset towards the inside of the landing gear compartment with respect to the said panel. There is a jack inserted between the panel and the structure, inside the landing gear compartment to control pivoting of the panel towards the outside of the fuselage when the landing gear is being extended.

The pivot pin is located inside the landing gear compartment due to the fact that in practice, it is impossible to place hinges directly onto the fuselage, particularly to maintain aerodynamic continuity of the fuselage.

For safety reasons related to risks of tires bursting, it is desirable that a landing gear door can be opened and closed without coming into contact with the wheels when the landing gear is extended.

Existing doors with pivoting one-piece panels cannot solve this problem, because the end of the panel interferes with the wheels during its opening and closing movements when the landing gear is extended.

PRESENTATION OF THE INVENTION

The main purpose of the invention is a door for an aircraft landing gear, with an innovative design such that it does not come into contact with the wheels during opening and closing movements when the landing gear is extended.

According to the invention, this objective is achieved by means of an aircraft landing gear door comprising a panel capable of pivoting about a pivot pin on an aircraft structure, and means of controlling pivoting, inserted between the panel and the structure in which the panel is formed from at least two rigid parts hinged to each other about a hinge pin approximately parallel to the pivot pin, dynamic control means being provided to enable progressive and controlled folding of rigid parts about the said hinge pin when the control means are actuated to open the door, and conversely, in which the control means are inserted between the aircraft structure and a first of the rigid parts connected to the said structure through the pivot pin, characterised in that a thrust plate is hinged to the inside of the second rigid part, close to one of its edges opposite to and parallel to the hinge pin, the thrust plate being connected to the dynamic control means so as to automatically open the door when a predetermined downwards force is applied to the thrust plate.

This arrangement provides a means of progressively reducing the space occupied by the panel in a controlled manner as the door opens, particularly the space occupied in the vertical direction, and vice versa. This prevents the panel from touching a landing gear wheel when the landing gear is already extended. This arrangement also enables the door to open by gravity so that the landing gear can extend when the control means are inoperative. In this case, the door is not required to close again by itself.

In one preferred embodiment of the invention, the dynamic control means include two door panel rods each hinged onto one of the rigid parts at one of their ends and a main connecting rod hinged between the other ends of the door panel rods and the aircraft structure.

This arrangement provides a means of automatically opening the door by gravity if there is a failure in the control means, by placing the thrust plate under a wheel of the landing gear and setting the predetermined force equal to not more than the mass of the landing gear when the aircraft is close to the ground.

In this improvement, the thrust plate is advantageously connected through at least one auxiliary connecting rod to the ends of the door panel rods hinged onto the main connecting rod.

As shown very diagrammatically inFIGS. 1A and 1B, the invention relates to an aircraft landing gear door10. Such a door10is designed to close off a landing gear compartment12in which the landing gear is stored when the landing gear is retracted.

The door10comprises a panel14with a shape complementary to the shape of an opening formed in the part16of the outer skin of the aircraft in which the landing gear associated with the said door is located. This part16of the outer skin of the aircraft is usually a fuselage or wing element.

The panel14is supported by the aircraft structure inside the landing gear compartment12, through rigid arms18fixed to the panel14and capable of pivoting on the said structure about a pivot pin20. This pivot pin is usually arranged in a direction approximately parallel to the longitudinal axis of the aircraft and is located on the outside of the door from the said longitudinal axis.

Pivot control means, usually consisting of a jack22, are inserted between the panel14and the aircraft structure, inside the landing gear compartment12. More precisely, the ends of the jack are connected to the rigid arms18and to the said structure, by pivots.

This arrangement enables the door to pass from a closed state shown inFIG. 1Ato an open state shown inFIG. 1B, when the control means are actuated.

When the door10is in its closed state, it provides aerodynamic continuity of the outer skin of the aircraft in the area concerned.

According to the invention, the panel14is formed from two rigid parts14aand14bhinged to each other edge to edge about a hinge pin24. This hinge pin24is in a direction approximately parallel to the pivot pin20.

The arms18are fixed to the first part14aof the panel14such that this first part14apivots directly about the pivot pin20when the control means are actuated. The hinge pin24connects the second part14bof the panel14to the edge of the first part14afurthest from the pivot pin20.

Furthermore, the door10comprises dynamic control means26designed to control the dynamics of the second part14bof the panel14when the control means are actuated. More precisely, the dynamic control means26are designed to provide controlled progressive folding of the rigid parts14aand14babout the hinge pin24when the control means are actuated so as to open the door, and vice versa. This action of the dynamic control means26can be more easily understood by comparingFIGS. 1A and 1B.

In practice, the kinematic control means26are composed of a mechanism that connects each of the rigid parts14aand14bto each other and to the aircraft structure, inside the landing gear compartment12.

In the embodiment shown inFIGS. 1A and 1B, this mechanism comprises at least two door panel rods28aand28band at least one main connecting rod30. One end of door panel rod28ais hinged to the first part14aof panel14, one end of the door panel rod28bis hinged to the second part14bof the panel14and one end of the main connecting rod30is hinged to the aircraft structure. Finally, the other ends of door panel rods28aand28band the main connecting rod30are hinged together.

In the embodiment shown inFIGS. 1A and 1B, the two parts14aand14bof the panel14are approximately the same width. However, their width may be slightly different, without going outside the scope of the invention.

Note also that the panel14may be formed from more than two rigid parts hinged together without going outside the scope of the invention. In this case, the dynamic control means26are modified so as to enable progressive controlled folding of each part of the panel.

When the door10is closed as shown inFIG. 1A, the different parts14a,14bof the panel14are aligned with each other and with the adjacent part16of the outer skin of the aircraft.

When the jack22is actuated so as to open the door10, the first part14aof the panel14is pivoted towards the outside of the aircraft, about the pivot hinge20.

Simultaneously, the dynamic control means26pull the second part14bof the door14towards the inside of the aircraft, because the main connecting rod30is hinged to the aircraft structure directly and its length is invariable, and the length of the door panel rods28aand28bis also invariable. Consequently, the second part14bof the panel14progressively folds inwards in a controlled manner towards the inside of the landing gear compartment12, rotating about the hinge pin24, as shown inFIG. 1B.

Due to the arrangement that has just been described, the space necessary for movement of the door10according to the invention is smaller than in the case of a one-piece door according to prior art. In particular, the dimension of the door in the vertical direction is reduced by approximately half when the door is open, in the case in which the two parts14aand14bhave the same width.

FIGS. 2A,2B and3show a second embodiment of the invention. This second embodiment is an improvement to the first embodiment, although all elements are identical in each embodiment. Only elements specific to this improvement will be described below, in order to simplify the description.

A rigid thrust plate32is hinged, through a hinge pin34, to the inside of the second part14bof the panel14. More precisely, the pin34connects one edge of the thrust plate32to the second part14bclose to the edge of this part opposite the hinge pin24.

The edge of the thrust plate32opposite the pin34is connected to the dynamic control means26by at least one auxiliary rod36. More precisely, one end of the auxiliary rod36is hinged to the ends through which the main connecting rod30and the door panel rods28aand28bare hinged to each other.

As shown inFIG. 2A, the arrangement that has just been described is such that, when the door10is closed, the thrust plate32is located above the second part14bof the panel14and is inclined downwards in the direction towards the pin34. More precisely, the angle of inclination of the thrust plate32with respect to the horizontal is then between about 30° and about 45°.

Furthermore, and as shown in chained dotted lines inFIG. 3, the thrust plate is then located below one or several of the wheels38of the landing gear.

Under these conditions, if the control jack22is inoperative when the landing gear needs to be extended, the mass of the landing gear when the aircraft is close to the ground applies a downwards force onto the thrust plate32, sufficient to open the door automatically as shown inFIGS. 2B and 3. The arrangement shown in these Figures is such that the door opens automatically when a predetermined force equal to not more than the above-mentioned mass is applied downwards onto the thrust plate32.

Thus, the improvement shown inFIGS. 2A,2B and3guarantees that the door10can open automatically and therefore the landing gear can be extended automatically by gravity when the control means of the said door are inoperative.