NO20200630A1

NO20200630A1 - A skid landing gear suspension device

Info

Publication number: NO20200630A1
Application number: NO20200630A
Authority: NO
Inventors: Svein Even Blakstad
Original assignee: Griff Aviation As
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2021-05-05

Description

A SKID LANDING GEAR SUSPENSION DEVICE

The present invention relates to a skid landing gear suspension device, and more specifically to a skid landing gear suspension device for an aerial vehicle such as a drone.

BACKGROUND

A key aspect of aerial vehicles, and in particular drones, is weight. The lighter the aerial vehicle is, the more lifting capacity it may have, and a longer flight-time may be achieved. As such, design of aerial vehicles today are on a large part based on weight-effective designs.

Also, the landing gear of an aerial vehicle such as a drone, and in particular heavy aerial vehicles, should preferably comprise suspension, such that the aerial vehicle may land softly on the ground even if the downwards speed is great. A soft landing reduces long-term effects of stress and strain on the body and landing gear of the aerial vehicle, and also reduces impact on the cargo the aerial vehicle may carry.

Most drone landing gears are of the skid type. A skid landing gear may comprise a skid element connected to the aerial vehicle by cross beams. Some skid landing gears comprises suspension, but a problem with existing suspension skid landing gears is that the skid element do not sufficiently adapt to the ground, such that the aerial vehicle may not rest properly on the ground even when the vehicle comes to a standstill. There is thus a need for a skid landing gear suspension device that allows the landing gear to adapt to the ground, even in a lateral direction. Also, existing skid landing gear suspension devices may comprise several elements and complex mechanical parts, such that existing skid landing gear suspension devices are both expensive to manufacture and heavy.

It is therefore a need for a skid landing gear suspension device that allows the skid element to adapt to the ground. It is a further advantage to devise a skid landing gear suspension device made from simple and cost-effective components. It is an objective of the present invention to achieve this and to provide further advantages over the state of the art.

Documents useful for understanding the field of technology include US 20130248650 A1, US 20170177773 A1, US 20160329203 A1 and US 3717208 A.

SUMMARY

It is an object of the present invention to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem.

According to a first aspect, there is provided a skid landing gear suspension device for an aerial vehicle. The skid landing gear suspension device comprises a skid element and a support element. A link arm is pivotably connected to the support element and connects the skid element and the support element. A suspension hub is provided on one of the link arm and the skid element, the suspension hub is arranged in an opening on the other one of the link arm and the skid element. At least one damper segment is provided in the opening for damping rotation of the suspension hub in the opening, and a biasing element allows tilting of the suspension hub in the opening.

According to a second aspect, there is provided a skid landing gear suspension device for an aerial vehicle, comprising a skid element and a support element. A link arm is pivotably connected to the skid element and connecting the skid element and the support element. A suspension hub is provided on one of the link arm and the support element, the suspension hub is arranged in an opening on the other one of the link arm and the support element. At least one damper segment is provided in the opening for damping rotation of the suspension hub in the opening, and a biasing element allows tilting of the suspension hub in the opening.

According to another embodiment of the invention, the biasing element is arranged between the skid element and the link arm.

According to another embodiment of the invention, the biasing element is arranged between the support element and the link arm.

According to another embodiment of the invention, the suspension hub extends through the biasing element.

According to another embodiment of the invention, the at least one damper segment is provided between a suspension hub body and a sidewall.

According to another embodiment of the invention, a gap is provided between the suspension hub body and the sidewall, allowing tilting of the suspension hub in all directions.

According to another embodiment of the invention, the damper segments are provided in a longitudinal direction of the suspension hub.

According to another embodiment of the invention, the suspension hub comprises a flange for securing the skid element to the suspension hub.

According to another embodiment of the invention, the flange comprises a beveled surface for increased tilting of the suspension hub in the opening.

According to another embodiment of the invention, the suspension hub comprises a suspension hub body provided with a generally square cross section.

According to another embodiment of the invention, the opening is provided with a generally square cross section.

According to another embodiment of the invention, the biasing element is a spring washer.

The present invention will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the invention by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the invention.

Hence, it is to be understood that the herein disclosed invention is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an" and "the" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present invention, when taken in conjunction with the accompanying figures.

Figure 1 shows a perspective view of an embodiment of a skid landing gear comprising two skid landing gear suspension devices.

Figure 2 shows a detailed perspective view of an outside of a skid landing gear suspension device.

Figure 3 shows a detailed perspective view of an inside of the skid landing gear suspension device.

Figure 4a shows the location of a cross section A-A on a skid landing gear.

Figure 4b shows the cross section A-A through a suspension hub and a skid element, normal to a longitudinal direction of the skid element.

Figure 5a shows the location of a cross section B-B on the skid landing gear.

Figure 5b shows the cross section B-B through a suspension hub and a skid element, normal to a longitudinal direction of the suspension hub.

Figure 6 shows an exploded view of the skid landing gear suspension device.

DETAILED DESCRIPTION

The present invention will now be described with reference to the accompanying figures, in which preferred example embodiments of the invention are shown. The invention may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the invention to the skilled person.

Referring initially to figure 1, an embodiment of a skid landing gear 1 is shown. The skid landing gear 1 shown in figure 1 is intended to be mounted on a left side of an aerial vehicle, and an aerial vehicle would typically comprise two such landing gears on an undercarriage of the vehicle; one skid landing gear 1 positioned on each side of the aerial vehicle. Two skid landing gears 1 on the aerial vehicle could be formed symmetrical, as a skilled person would appreciate.

The skid landing gear 1 illustrated in figure 1 comprises two skid landing gear suspension devices 2. Each skid landing gear suspension device 2 comprises a skid element 3, or a portion of a skid element 3. In the illustrated embodiment, both skid landing gear suspension devices 2 comprises the same skid element 3, but each skid landing gear suspension device 2 may also comprise individual skid elements 3. The skid landing gear suspension devices 2 may be arranged at, or close to, terminal ends of the skid element 3, as in the illustrated embodiment. A skid element 3 may be a skid profile or a skid strut, configured for contacting the ground when the aerial vehicle the skid landing gear 1 is supporting, is resting on the ground. A skid landing gear suspension device 2 further comprises a support element 4. The support element 4 may be a cross bar, or simply a portion of the undercarriage of the aerial vehicle. The support elements 4 of the illustrated embodiment are legs configured for mounting on an aerial vehicle, and two support elements 4 are supporting the skid element 3. The support element 4 is preferably a rigid element, to which a link arm 5 is pivotably connected. The link arm 5 thus connects the skid element 3 and the support element 4.

Referring now to figures 2 and 3, the skid landing gear suspension device 2 is shown in greater detail. As described above, the skid landing gear suspension device 2 comprises the skid element 3 and the support element 4. The link arm 5 is pivotably connected to the support element 4 at a pivotable connection 6, and can thus rotate freely relative to the support element 4. The pivotable connection 6 may be any means known in the art of pivotably connecting two elements, such as a bolt and a receiving hole, an axle and a bearing, etc. The link arm 5 is preferably connected to the support element 4 in a way that allows the link arm 5 to pivot about an axis relative to the support element 4, but is restricted from movement or rotation in other directions.

In the illustrated embodiment, the link arm 5 is positioned on an inside of the skid element 3, but the link arm 5 may alternatively be positioned on an outside of the skid element 3, or even on top. The link arm 5 is connected to the skid element 3 by means of a suspension hub 7 (visible only in figure 2). The interconnection between the link arm 5, suspension hub 7 and skid element 3 is described in greater detail with reference to figures 4a,b and 5a,b.

Referring now to figures 4a and 4b, figure 4a shows the location of a cross section A-A on the skid landing gear 1. The cross section A-A is shown in figure 4b and is coincident with a centre axis of the suspension hub 7. In the illustrated embodiment the cross section A-A is normal to a longitudinal direction of the skid element 3.

The suspension hub 7 is provided on the link arm 5. In the illustrated embodiment, a suspension hub fastening means 8, such as a bolt, secures the suspension hub 7 to the link arm 5 in order to ease manufacturing and assembly, but the suspension hub 7 may alternatively be a protruding portion of the link arm 5, or the suspension hub 7 may be welded or otherwise rigidly connected to the link arm 5. The suspension hub 7 is arranged in an opening 9 on the skid element 3. The opening 9 may extend through the skid element 3, as in the illustrated embodiment. The opening 9 may also be provided on an element in connection with the skid element 3, and the skid element 3 may in an alternative embodiment be a part in connection with the actual landing skids. The suspension hub 7 may comprise a suspension hub body 10 and a flange 11. In the illustrated embodiment, the suspension hub body 10 is arranged in the opening 9, and the flange 11 extends past the opening 9 and secures the skid element 3 to the link arm 5.

The skid landing gear suspension device 2 comprises a biasing element 12. The biasing element 12 may be provided between the link arm 5 and the skid element 3. The biasing element 12 may exert a force as it is compressed and tries to maintain its initial shape. The biasing element 12 may be arranged around the suspension hub 7, i.e. the suspension hub 7extends through the biasing element 12. The biasing element 12 may as such be a spring washer. If the biasing element 12 is arranged around the suspension hub 7, the biasing force may be evenly distributed about the suspension hub 7 and towards the skid element 3. The biasing element 12 may also be a spring, or an elastic material, capable of forcing the skid element 3 towards the flange 11. The biasing element 12 may be a part of either the link arm 5, the skid element 3, or it may be a separate element as in the illustrated embodiment.

As the biasing element 12 is compressible, it allows the suspension hub 7 to be tilted T in the opening 9, i.e. the skid element 3 may tilt T relative to the suspension hub 7 and the link arm 5 in a direction indicated with T and illustrated in figure 4b by a double arrow. Tilting T is defined as rotation from a first position where a longitudinal axis of the suspension hub 7, or in particular, a longitudinal axis of the suspension hub body 10, is parallel with a longitudinal axis of the opening 9 to a second position where the two axes are not parallel. In the cross section of figure 4b, this tilting T may occur as the skid element 3 is rotated with or against the clock in the plane of figure 4b. Tilting T may also occur out of the plane of figure 4b. The centre of such a rotation or tilt of the skid element 3 may be anywhere, i.e. either within the opening 9, or outside. The skid element 3 may as such tilt T and adapt to an uneven or slanting ground in a sideways direction of the aerial vehicle. The allowed tilting T of the skid element 3 also reduces impact in a sideways direction as the aerial vehicle impacts the ground.

The biasing element 12 causes the suspension hub 7 to align towards the first position if external forces do not exceed the biasing force. If forces applied to the skid element 3 exceeds the biasing force of the biasing element 12, the skid element 3 tilts. A gap 13 may be provided between portions of the suspension hub body 10 and an internal sidewall 14. The sidewall 14 is the internal portion of the skid element 3 surrounding the opening 9. In order to allow tilting T in all directions, the gap 13 may preferably be provided between the entire suspension hub body 10 and the sidewall 14. If two skid landing gear suspension devices 2 are connected to the same skid element 3, tilting T of the skid element 3 would thus generally be limited to the direction indicated in figure 4b.

The flange 11 may additionally be provided with a bevelled surface 15 on an underside of the flange 11. The bevelled surface 15 is thus configured for abutment with the skid element 3. The bevelled surface 15 may both accommodate and increase tilting T of the skid element 3 relative to the suspension hub 7. The bevelled surface 15 may be conical to further accommodate such tilting action.

The skid element 3 may additionally be provided with pads 16 for reducing wear and tear on the skid element 3. The pads 16 may be formed of rubber or plastic for increasing friction with the ground, or for further reducing impact with the ground if the aerial vehicle is landing on a hard surface.

Referring now to figures 5a and 5b, figure 5a shows the location of a cross section B-B on the skid landing gear 1. The cross section B-B is shown in figure 5b and is normal to a centre axis of the suspension hub 7. In the illustrated embodiment the cross section B-B is in a longitudinal direction of the skid element 3.

At least one damper segment 17 is provided between the suspension hub 7 and the sidewall 14. More preferably, the at least one damper segment 17 may be provided between the suspension hub body 10 and the sidewall 14. The skid landing gear suspension device 2 may comprise any number of damper segments 17, preferably a plurality of damper segments 17, and more preferably four. If only one damper segment 17 is provided between the suspension hub 7 and the sidewall 14, it may be arranged about the suspension hub body 10 and have varying thickness around the suspension hub body 10.

The suspension hub body 10 may preferably have a rectangular, and more preferably square, cross section, such that four damper segments 17 may be arranged in the opening 9. The opening 9 may have a cross section corresponding to that of the suspension hub body 10. In the illustrated embodiment, the opening 9 is square, and one damper segment 17 is arranged in each corner of the opening 9. The damper segments 17 may extend along the length of the opening 9. The suspension hub body 10 has a corresponding square cross section, and in a first, unloaded position the square suspension hub body 10 may be positioned rotated 45° relative to the square opening 9. The damper segments 17 may have a circular or triangular cross section in a non-compressed state, or they may as such have any shape in a non-compressed state. The shape of the damper segments 17 may correspond to a triangle with rounded edges when provided between the sidewall 14 and the suspension hub 7, as in the illustrated embodiment. The damper segments 17 retain the suspension hub body 10 in a first position in the opening 9 where the suspension hub body 10 is not rotated relative to the opening 9, and the suspension hub 7 and link arm 5 is as such held in the neutral, first position as illustrated in figure 5b.

As the aerial vehicle impacts the ground, the skid element 3 touches the ground. The skid element 3 is thus forced towards the aerial vehicle, i.e. upwards in figure 5b. As the link arm 5 is free to rotate about the pivotable connection 6 to the support element 4, the suspension hub 7, being rigidly connected to the link arm 5, is rotated within the opening 9. The suspension hub 7 is thus rotated in the direction R1 relative to the opening 9. As the suspension hub 7 is rotated, the damper segments 17 are compressed between the suspension hub body 10 and sidewall 14. The forces from the landing impact (depending among others on the weight of the aerial vehicle and the downwards speed of the aerial vehicle) and the stiffness of the damper segments 17 determine how much the suspension hub body 10 may rotate in the direction R1 in the opening 9. Such a damping system is also known as torsional damping. The aerial vehicle comes to a standstill with the skid landing gear suspension device 2 in a second position.

As the aerial vehicle takes flight, the return energy of the damper segments 17, and gravity, forces the skid element 3 back to its first position, and the suspension hub 7 is thus rotated in an opposite, second direction R2 in the opening 9. The damper segments 17 dampens rotation of the suspension hub body 10 in both directions R1 and R2, and thus prevent the suspension hub 7 from rotating beyond the first position. The suspension hub 7 thus comes to a rest in the opening 9 in the first position where the link arm 5 and skid element 3 again are arranged to absorb an impact upon landing of the aerial vehicle.

A skid landing gear 1 may comprise a plurality of skid landing gear suspension devices 2, and one or more skid elements 3. In a preferred embodiment, a skid landing gear 1 comprises two skid landing gear suspension devices 2 and one skid element 3. The two skid landing gear suspension devices 2 thus comprise the same skid element 3. A skid landing gear 1 comprising two skid landing gear suspension devices 2 allows longer travel of e.g. a front part of the skid element 3, and the skid element 3 may as such be angled relative to the aerial vehicle upon standstill of the aerial vehicle on the ground, and thus adapt to unevenness’ on the ground as the vertical displacement of the front and rear part of a skid element 3 may be dissimilar. A skid landing gear 1 may even comprise skid landing gear suspension devices 2 with damper segments 17 of different hardness, and different lengths of the link arm 5, compensating for e.g. differences in weight distribution on the aerial vehicle.

Referring now to figure 6, an exploded view of the illustrated embodiment of the skid landing gear suspension device 2 is shown. A bolt 18 may pivotably connect the link arm 5 to the support element 4. A bushing 19 may be provided around the bolt 18, in order to reduce friction between the link arm 5 and the bolt 18. The biasing element 12 is provided between the link arm 5 and the skid element 3, and the suspension hub 7 extends through the opening 9 in the skid element 3. The suspension hub 7 extends through the biasing element 12 and is fixed to the link arm 5 by the suspension hub fastening means 8. Four damper segments 17 are provided in the opening 9 in longitudinal corners of the sidewall 14. The damper segments 17 are retained inside the opening 9 between the flange 11 of the suspension hub 7 and the biasing element 12.

The aforementioned description relates to the illustrated embodiment. In a second embodiment, the suspension hub 7 and the opening 9 are provided reversed, such that the link arm 5 is provided with an opening 9, and the skid element 3 comprises the suspension hub 7. The function and components of such a reversed skid landing gear suspension device 2 are otherwise similar to the first embodiment, and the damper segments 17 are in the second embodiment provided in the opening 9 in the link arm 5. The biasing element 12 is provided between the link arm 5 and the skid element 3, and tilting T of the skid element 3 causes the suspension hub 7 to tilt accordingly in the opening 9, instead of the skid element 3 tilting relative to the suspension hub 7, as in the first embodiment.

In a third embodiment of the skid landing gear suspension device 2, the link arm 5 is pivotably connected to the skid element 3 instead of the support element 4. In the third embodiment, the suspension hub 7 is provided on the link arm 5, and the opening 9 is provided on the support element 4 instead of the skid element 3. The suspension hub 7 is arranged in the opening 9, and at least one damper segment 17 is provided in the opening 9 for damping rotation R of the suspension hub 7 in the opening 9. The biasing element 12 may be provided between the link arm 5 and the support element 4, and the biasing element 12 may be provided around the suspension hub 9. The biasing element 12 allows tilting T of the suspension hub 7 in the opening 9. In the third embodiment, tilting of the skid element 3 causes the skid element 3, link arm 5 and suspension hub 7 to tilt T relative to the opening 9 in the support element 4. The function and components of such a reversed skid landing gear suspension device 2 are otherwise similar to the first embodiment.

In a fourth embodiment of the skid landing gear suspension device 2, the suspension hub 7 and opening 9 are provided reversed to that of the third embodiment, such that the link arm 5 is provided with an opening 9, and the support element 4 comprises the suspension hub 7. The function and components of such a reversed skid landing gear suspension device 2 are otherwise similar to the third embodiment, and the damper segments 17 are in the fourth embodiment provided in the opening 9. The biasing element 12 is provided between the link arm 5 and the support element 4, and tilting T of the skid element 3 causes the link arm 5 to tilt accordingly relative to the suspension hub 7 provided on the support element 4, instead of the link arm 5 and suspension hub 7 tilting relative to the opening 9, as in the third embodiment.

The person skilled in the art realizes that the present invention is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Claims

1. A skid landing gear suspension device (2) for an aerial vehicle, comprising: a skid element (3);

a support element (4);

a link arm (5) pivotably connected to the support element (4) and connecting the skid element (3) and the support element (4);

a suspension hub (7) provided on one of the link arm (5) and the skid element (3), the suspension hub (7) is arranged in an opening (9) on the other one of the link arm (5) and the skid element (3);

at least one damper segment (17) provided in the opening (9) for damping rotation (R1, R2) of the suspension hub (7) in the opening (9);

a biasing element (12) allowing tilting (T) of the suspension hub (7) in the opening (9).

2. A skid landing gear suspension device (2) for an aerial vehicle, comprising: a skid element (3);

a support element (4);

a link arm (5) pivotably connected to the skid element (3) and connecting the skid element (3) and the support element (4);

a suspension hub (7) provided on one of the link arm (5) and the support element (4), the suspension hub (7) is arranged in an opening (9) on the other one of the link arm (5) and the support element (4);

3. The skid landing gear suspension device (2) of claim 1, where the biasing element (12) is arranged between the skid element (3) and the link arm (5).

4. The skid landing gear suspension device (2) of claim 2, where the biasing element (12) is arranged between the support element (4) and the link arm (5).

5. The skid landing gear suspension device (2) of any one of the previous claims, where the suspension hub (7) extends through the biasing element (12).

6. The skid landing gear suspension device (2) of any one of the previous claims, where the at least one damper segment (17) is provided between a suspension hub body (10) and a sidewall (14).

7. The skid landing gear suspension device (2) of any one of the previous claims, where a gap (13) is provided between the suspension hub body (10) and the sidewall (14), allowing tilting of the suspension hub (7) in all directions.

8. The skid landing gear suspension device (2) of any one of the previous claims, where the damper segments (17) are provided in a longitudinal direction of the suspension hub (7).

9. The skid landing gear suspension device (2) of any one of the previous claims, where the suspension hub (7) comprises a flange (11) for securing the skid element (3) to the suspension hub (7).

10. The skid landing gear suspension device (2) of claim 9, where the flange (11) comprises a beveled surface (15) for increased tilting of the suspension hub (7) in the opening (9).

11. The skid landing gear suspension device (2) of any one of the previous claims, where the suspension hub (7) comprises a suspension hub body (10) provided with a generally square cross section.

12. The skid landing gear suspension device (2) of any one of the previous claims, where the opening (9) is provided with a generally square cross section.

13. The skid landing gear suspension device (2) of any one of the previous claims, where the biasing element (12) is a spring washer.