JPS59179500A - Front wheel type landing device for aircraft - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to landing gear, and more particularly to nosewheel type landing gear such as may be found on aircraft such as fighter jets.

In this type of aircraft, the nosewheel landing gear occupies as little space as possible when in the "retracted"position;
In particular, it is important that the length is as short as possible. However, the streamlined shape of the aircraft structure requires that (during horizontal flight) the wheels lie in a plane approximately perpendicular to the vertical plane passing through the axis of the aircraft.

For example, reducing the space occupied by compacting the parts of the landing gear by compressing the shock absorbers and rotating the wheels by e.g. 90° when the landing gear moves from the "extended" position to the "retracted" position. There are a variety of landing gears in which the landing gear rotates about an axis perpendicular to the aforementioned vertical plane, so that when the landing gear rotates about an axis perpendicular to the aforementioned vertical plane, the wheels initially parallel to the vertical plane When fully retracted, it ends up in a perpendicular plane, i.e. the wheel occupies a flat position.

However, in all conventional devices, when the landing gear is compacted to reduce the space it occupies in the lengthwise direction, the wheels are moved laterally with respect to the axis of the landing gear, resulting in a housing of greater width. demanded.

SUMMARY OF THE INVENTION Therefore, the present invention seeks to provide a nose wheel landing gear for an aircraft, which is simple in construction and allows a minimum retraction volume to be achieved by a structure that avoids occupying extra space in the lateral direction. It is.

That is, according to the present invention, a shock absorber is constituted by a rod and a cylinder, the rod is slidable in the cylinder, and the protruding end of the rod is connected to a fixed point of an aircraft structure; a sliding means connected to a cylinder that is the other end of the shock absorber; a guide sheath disposed around the shock absorber; a slidable bearing disposed between an inner wall of the guide sheath and an outer wall of the cylinder; engagement means for at least rotatably coupling the cylinder to the guide sheath when the shock absorber is in the released position; a strut surrounding the guide sheath; A nose wheel landing gear for an aircraft is characterized in that it includes control means for retracting the guide sheath into the strut and means for rotating the guide sheath when the guide sheath is retracted into the strut.

In an embodiment of the landing gear of the invention, said control means for exerting a traction force on said guide sheath to draw it into said strut is linked at one end to the structure of said aircraft and at the other end to said strut. It consists of a bendable side place that is rotatably linked to a bendable side place, one end of the side place is linked to a strut throat including a crank, and one end of the crank is linked to a guide sheath by a connecting rod. .

This means that landing gear docking requires only two fixation points on the aircraft structure.

The invention will now be described with reference to the accompanying drawings.

Since both Figures 1 and 2 show the same landing gear in two different positions, the same reference numbers refer to the same parts, and the description of the landing gear is primarily in the first part.
Although reference has been made to the figures, it is preferable to view both figures for a thorough understanding.

In particular, reference is made to FIG. 1, which shows a nosewheel landing gear 2 suitable for attachment to the structure of an aircraft, generally indicated by the reference numeral 1.

The landing gear 2 is generally connected to the structure by any means known in the art via a fixing point 3, which fixing point includes an axis of rotation.

More specifically, the landing gear consists of a shock absorber 4 constituted by a rod 5 and a cylinder 6.

The rod 5 is adapted to slide within a cylinder 6 by means of a piston 7 which includes a throttle and shock absorbing means, as is well known, and which includes a fluid spring (for example an air chamber).
(not shown in FIG. 1 in order to simplify the drawing).

The end of the shock absorber 4, i.e. the protruding end of the rod 5, is connected to the fixed point 3 of the aircraft structure 1, for example by a rotation axis 9, while the other end of the shock absorber, i.e. the end 10 of the cylinder 6, is Wheel (wheel) 12
The wheel is attached to the support 11 via an axis of rotation 13.

The shock absorber 4 is arranged in a guide sheath, which is preferably in the form of a circular cylinder 14 that surrounds most of the length of the shock absorber 4. The cylinder 6 of the shock absorber 4, in particular the shock absorber, is slidable in the longitudinal direction within the guide sheath 14, the outer wall of the cylinder 6 being fitted with two bearings 15 as shown, for example.
and guides the shock absorber 4 in the longitudinal direction when the cylinder 6 moves relative to the guide sheath.

Furthermore, a releasable engagement member 17 is located near the bottom of the guide sheath 14 and cylinder 6.

These engagement members are constituted by cams cooperating with each other by means of a protruding part and a recessed part, which are shown schematically in the drawing, the recessed part being designated by 18 and the protruding part by 19. As will be explained in more detail below, when the foil 12 is, for example, no longer on the ground, and therefore when the shock absorber is released, i.e. the rod and the cylinder move relative to each other and the rod 5 projects as far as possible from the cylinder. At this time, the cylinder 6 and the guide sheath are fixed at least during rotation by these engaging members.

The landing gear further includes a strut 21 surrounding the aforementioned parts, namely the guide sheath 14 and the yoke absorber 4, the strut being rotatably mounted about the rotation point 3 (as described above). 2
The guide sheath 14 is supported for rotational and translational sliding movement by an annular guide bearing 22 consisting of two (23 and 24). The landing gear also includes a box 25 in which there is a rack arrangement 26, which comprises, for example, an endless screw 27 mounted rotatably about a bearing 28 perpendicular to the drawing and a longitudinal direction of the landing gear. and a circular sleeve 29 centered on the axis of symmetry 50.

Sleeve 29 has an outer portion 30. Joint link 31
connects the bottom (end) 10 of the shock absorber to the sleeve 29
It is connected to the external portion 30 of the. The articulated link 31 is conventionally made from two levers 32 and 33, with the lever 3
2 and 33 are rotatably mounted to each other about an axis 34 and are rotatable about two other axes of rotation 35 and 36 located respectively in the outer part 30 of the sleeve 29 and the bottom 10 of the cylinder 6. installed.

Furthermore, the inner wall of the strut 21 has a guide groove 38, which is helical and extends over an angle of at least 90° over a height h, which is the height h of the landing gear as described above. The two groove following wheels 40 and 41 are arranged around the axis of symmetry of the top of the guide sheath so as to cooperate with the two guide grooves 38 and 39 respectively. Arranged symmetrically, these guide grooves act as rails on which the wheel wheels run.

Finally, as previously mentioned, the nosewheel landing gear must be capable of closing in two positions. That is, in the extended position shown in Figure 1 (the position where the landing gear cooperates with the ground 20 during takeoff and landing) and in the second position shown in Figure 2, the aircraft minimizes air resistance during flight. The landing gear in the housing of the aircraft structure so as to reduce “
retracted” position).

Under these conditions, an internal locking actuator 42 is provided to move the landing gear from the extended position to the ``retracted'' position, or vice versa. It is constituted by a cylinder 44.

One end of the actuator, in this case the rod 43, is connected to the intermediate part of the strut 21 via a protruding lug 45, and the other end of the actuator, in this case the cylinder, is connected to a fixed point 46 on the structure 1 of the aircraft. There is. The landing gear includes a rigid link 80 which is connected at one end to a fixed point 83 via a knuckle joint and at the other end via a projecting lug 82 and to an axis 8 with two rotational degrees of freedom.
1 cooperates with the bottom of the guide sheath 14 to rotate around the guide sheath 14.

The above description assumes that the landing gear is not shown in FIG.
Concerning a nosewheel landing gear which, when moving from a 'retracted' position to a 'retracted' position, becomes more or less compact without occupying much space laterally, and which allows the nosewheel to rotate over 90' between these two positions. be.

When the landing gear moves from one of these positions to the other, the following actions occur.

The following description relates to the operations that occur when the landing gear moves from its ``extended'' position of FIG. 1 to its ``retracted'' position of FIG. 2. From the pull-in position
The opposite movement to the extended position can be deduced very easily from the description for the first case.

Assuming that the aircraft is resting on the ground 20 by the landing gear, including the nosewheel landing gear 2, the landing gear 2 exerts a force on the shock absorber at least equal to its weight, thereby causing the cylinder 6 to move away from its rest position. raised to at least an intermediate position on the rod 5 so that the engagement members are separated (the protruding part 19 is separated from the recessed part 18 and the cylinder 6 is free to rotate relative to the kite sheath 14).

If the aircraft runs along the ground and experiences a large shock, the shock absorber can absorb the shock by having the rod 5 enter the cylinder 6 a variable distance. Also, because the engagement members are separate, the pilot can drive the aircraft by driving the sleeve 29 and by means of the rack arrangement, which rotates the wheel 12 by means of the articulated link 31 and rotates the cylinder 6. Nose wheel landing gear thus provides all of the desired characteristics of such landing gear, namely shock absorption and operation when the aircraft is on the ground.

In contrast, during takeoff of the aircraft, the wheel 12 is lifted off the ground 20 at a certain moment and the shock absorber is no longer subject to compressive forces. As a result, the shock absorber is extended by the elastic force of the air chamber, the engaging members 17 engage with each other, and the protruding portion 19 enters the recessed portion 18, thereby preventing rotation between the cylinder 6 and the guide sheath 14. . The force that holds the engagement member in the engaged position is provided by a fluid spring in the air chamber.

Under these conditions, after the aircraft takes off and the landing gear has been extended for a predetermined period, the pilot may retract the landing gear. To do this, the pilot controls the actuator 42, which in this embodiment is first unlocked and then shortened in length. For this purpose, the actuator pulls on the strut, causing it to rotate about the fixed point 3. During this rotation, axis 81 is moved away from point 83 so that rigid link 80 exerts a traction force on guide sheath 14 . The guide sheath is drawn into the strut 21 by this traction force.

However, in addition to the translational movement when the guide sheath is pulled upwardly, the guide sheath also has helical grooves 38 and 3
It is also rotated by wheels 40 and 41 cooperating with 9. In the illustrated embodiment, the guide sheath is rotated over 90'. Further, since the rotation of the cylinder 6 with respect to the guide sheath 14 is fixed due to the engagement of the engaging member 17, the cylinder 6 is also rotated by 90 degrees, and the wheel is rotated so that the wheel takes the position shown in FIG. Rotate by the same angle. This position is at right angles to the position shown in FIG.

It is clear from FIG. 2 that the shock absorber is compacted by the guide sheath 14 being retracted by a distance, and furthermore the wheel is aligned with the aforementioned axis 50.
can be rotated without moving away from it, so no lateral space is required. Such a landing gear serves the purpose of the invention to reduce the space occupied in the longitudinal direction without increasing the space occupied in the lateral direction.

Naturally, the cylinder 6 of the shock absorber is the joint link 3.
When rotated by 1, the sleeve 29 is also rotated 90', but this poses no difficulty since the rack arrangement is separated during take-off.

Although the above described arrangement of landing gear gives good results, this arrangement has drawbacks under certain circumstances.

In particular, this device requires fewer (3) anchoring points on the aircraft structure: point 3 where the strut is secured, point 46 where the control actuator is secured, and point 83 where the link is secured. .In some aircraft,
It is not always possible to find three fixed points.

The landing gear shown by the centerline in FIG. 3 requires only two fixation points.

FIG. 3 shows a nosewheel landing gear 101 for an aircraft having a structure 100. FIG. In order to understand what the structure of this landing gear is, it is preferable to refer to FIGS. 1 and 2.

One end 102 of the landing gear is fixed rotatably around an axis 103, and the axis itself is connected to the aircraft structure 100.
Fixed. Generally speaking, the landing gear 100 includes a stop 104, one end 102 of which is rotatably mounted about an axis 103.

At the other end, the guide sheath 105 protrudes as described above, and from the guide sheath one end of the shock absorber 106, in particular, the cylinder of the shock absorber protrudes as described above. The projecting end of the shock absorber 106 has a landing gear 107, preferably constituted by one or more wheels. Similarly, as previously discussed, the shock absorber, and in particular its protruding end, is connected to the bottom end of the strut 104 by an articulating link 108.

The landing gear 101 further includes a side place 109 which is rotatably linked at one end about a point or axis 111, which point 111 is fixed to the structure of the aircraft. The other end 112 is rotatably linked around a point or axis 113. The side place 109 is of the flexible type and in this embodiment consists of two levers 114 and 115 articulated with each other about an axis 116. However, the side place can be designed similarly to the rod of the actuator, ie a rod slidable in a cylinder with bending and equivalent shortening functions. The end 112 of the side place, linked to the strut 104 about a point 113, includes a projecting crank, for example constituted by an extension 117 of the lever 114. End 11B of the crank is linked to bottom end 119 of guide sheath 105 at point 121 by connecting rod 120. The connecting rods 120 are connected to the bottom 119 of the guide sheath 105 and the crank 11 for rotation about an axis, for example about a knuckle joint or a universal joint, depending on the arrangement.
It is connected to 7.

The landing gear naturally includes a device for controlling the alignment and misalignment of the two levers 114 and 115 forming the ``flex'' side place. For clarity of the drawing, such an actuator is not shown, but its design is easy for those skilled in the art.

Landing gear 101 operates as follows.

The landing gear is in its first extended position, i.e. position A in Figure 3.
Assume that

The operations that occur when the landing gear moves from the extended position shown at A to the retracted position shown at B in FIG. 3 are as follows. Recall that when the landing gear is retracted into the aircraft structure 100, the wheels rotate about the axis of the shock absorber sill 106. This feature has been described in connection with FIGS. 1 and 2 and will not be repeated again.

When the landing gear is in the extended position (A), the side places are fully extended. That is, levers 114 and 11
5 are almost on the same straight line. By means of a suitable device, e.g. an actuator as described above, the alignment of the side places is broken, e.g. by rotating lever 115 counterclockwise about point 111, causing a corresponding clockwise rotation of lever 114 relative to strut 104. cause rotation.

As a result, the crank 11 fixed to the lever 114
7 rotates clockwise and attempts to move point 118 away from point 121.

Therefore, point 118 corresponds to point 121 in the extended position of the landing gear.
Since it tries to move away from the position occupied by
As the connecting rod rotates, it exerts a traction force on the guide sheath 105, causing the landing gear to move into the extended position (
The guide sheath is moved into the strut 104 as it moves along the path from A) to the retracted position (B).

Compared to the embodiment described with reference to FIGS. 1 and 2,
This embodiment omits one of the fixed points on the aircraft.

This is especially important when the aircraft has little space, such as a fighter jet.

Naturally, the landing gear moves from the retracted position (B) to the extended position (A).
, the side place 109 is similarly aligned by the actuator and various rotations occur in the opposite direction, causing the point 118 to move towards the protruding end 119 of the guide sheath 105. This causes the guide sheath to exit the strut 1.04.

[Brief explanation of the drawing]

1 is a schematic side view, partially in section, of a first landing gear embodying the invention in an extended position; FIG. FIG. 2 is a view similar to FIG. 1, but showing the landing gear retracted position. FIG. 3 is a centerline schematic diagram showing the second landing gear of the present invention in both an extended position (solid line) and a retracted position (dotted line). Main reference numbers 1; Aircraft structure; 2; Landing gear; 4; Shock absorber; 5; Rod, former Nijilinda; 1
7: Engagement member, 21st strut, 14th guide system Patent Applicant: Meche Spain Bugatches, AR. Representative Patent Attorney Masahiko Arai

Claims (5)

[Claims] (1) A nyc-type abutment V having a structure consisting of a rod and a cylinder, a rod slidably inside the cylinder, and a protruding end of the rod connected to a fixed point on the aircraft structure.
- bar and the other end of the shock absorber). a sliding means connected to a ring; a guide sheath disposed around the shock absorber; a slidable bearing disposed between an inner wall of the guide sheath and an outer wall of the cylinder; and the shock absorber is in a released position. an engagement means for at least rotatably coupling the cylinder to the guide sheath; a strut surrounding the guide sheath; and a control means for applying a traction force to the guide sheath to draw the guide sheath into the strut; An aircraft nosewheel landing gear comprising: means for rotating the guide sheath when the guide sheath is retracted into the strut. (2) The landing gear according to claim 1, wherein the engaging means is constituted by a cam that projects from and is recessed from the outer wall of the cylinder and the inner wall of the guide sheath, respectively. (3) The control means for applying a traction force to the guide sheath is constituted by an actuator whose one end is fixed to the structure of the aircraft by a link means and whose other end is linked to the guide sheath by a link means. The landing gear according to claim 1, characterized in that: (4) The link means for linking the actuator to the guide sheath comprises a link in the strut, -HM is rotatably attached to the structure of the aircraft and the other end is attached to the guide sheath. A landing gear according to claim 3, characterized in that: (5) when the guide sheath enters the strut, said means for controlling rotation of said guide sheath extends over a predetermined angle of rotation and a predetermined height h);
a helical groove and groove following means fixed to said guide sheath, said groove following means adapted to rotate said guide sheath relative to said strut as said guide sheath is translated into said strut. 5. Landing gear according to any one of claims 1 to 4, characterized in that it is suitable for traveling along the groove at any time. (6) The control means applies a traction force to the guide sheath to draw the guide sheath into the strut,
consisting of a flexible side place, one end of which is linked to the structure of the aircraft and the other end of which is rotatably linked to the strut, one end of the side place is linked to a strut that includes a crank; 2. The landing gear according to claim 1, wherein one end of the crank is linked to the guide sheath by a connecting rod. (7) Landing gear according to claim 6, characterized in that the side places are constituted by two levers articulated with each other about a common point.