Landing gear with adjustable tire camber

Abstract

A landing gear assembly (100) includes a strut defining a first axis (300) and an axle (110) rotatably coupled to the strut about a second axis (304) and defining a third axis (302). The landing gear assembly further includes a wheel (120) rotatably coupled to the axle about the third axis (302). An adjustment assembly is coupled to the strut and to the axle. The adjustment assembly (130) is configured to provide selective adjustment of an angle between the first axis (300) and the third axis (302).

Description

LANDING GEAR WITH ADJUSTABLE TIRE CAMBERBACKGROUND

[0001] Aircraft are typically equipped with landing gear that enables the aircraft to taxi, takeoff and safely land on the ground. Some aircraft utilize landing gear that is retractable, i.e., the landing gear reciprocates between a deployed (extended) position and a stowed (retracted) position. While the vehicle is on the ground, the landing gear is deployed and supports the vehicle. Such landing gear typically incorporate shock struts that cushion landing impacts or bump perturbations and dampen repeat oscillations as well as the tendency for an aircraft to rebound or “bounce.” In flight, the landing gear retracts, which reduces drag. The reduction in drag lowers fuel consumption and allows for higher cruise speeds. Examples of a known deployable and retractable landing gear are described in U.S. Patent No. 10,549,848, issued to Klim et al., and currently assigned to Safran Landing Systems Canada, Inc., the disclosure of which is incorporated herein in its entirety.

[0002] Landing gear wheels are typically mounted to an axle that extends laterally from the shock strut. Landing gear in which the axles are cantilevered in this manner are prone to “squatting” under aircraft static weight, wherein both the axle and the shock struts deflect. The magnitude of deflection varies as a function of the aircraft static weight.

[0003] Squatting results in tire camber, which is the angle of the wheel relative to a vertical plane parallel when viewed from the front or rear of the landing gear. If the top of the wheel tilts outward, then the wheel has “positive” camber; if the top of the wheel tilts inward, the wheel has “negative” camber. Tire camber reduces the contact area of the tire with the ground surface, which may cause uneven tire wear.

[0004] Uneven tire wear caused by tire camber can be extreme and can result in more frequent than expected aircraft downtime and excessive maintenance costs. Most aircraft tires are equipped with a fuse plug that releases pressure from the tires and deflate them before excessive wear can cause a catastrophic failure. However, premature wear of aircraft tires can still lead to tire bursts that may cause loss of control, runway excursions, structural damage, or fire, any of which can result in passenger and crew injuries. In orderto minimize uneven tire wear, it is desirable to maintain the tire perpendicular to the ground.

[0005] FIGURES 1 and 2 show an embodiment of a known landing gear assembly 100 that accounts for squatting by providing a predetermined amount of positive wheel camber in the undeflected position. The landing gear assembly 50 includes a shock strut 52 configured to be coupled to an aircraft (not shown). The shock strut 52 includes a piston 54 slidably associated with a cylinder 56 for translational movement along a longitudinal axis 80. A torque link 58 is coupled at one end to the cylinder 56 and at another end to the piston 54 to prevent rotation of the piston relative to the cylinder about the longitudinal axis 80 while allowing translational movement of the piston 54 relative to the cylinder 56. Embodiments of the shock strut 52 are configured to be coupled to an aircraft in any suitable manner to mount the landing gear assembly 100 to the aircraft.

[0006] An axle 60 extends laterally from the piston 54. As best shown in FIGURE 2, a wheel 62 is rotatably mounted to the axle 60 for rotation about axis 82. The wheel 62 includes a tire 64 mounted to a rim 66, and a plurality of bearings 68 rotatably couple the rim 66 to the axle 60.

[0007] The axle fitting 114 is coupled to or integrally formed with the piston 53 so that the wheel 62 and axis 82 move with the piston. In some embodiments, the landing gear assembly includes a plurality of wheels. When the aircraft is parked or taxiing, the wheel 62 of the landing gear assembly 50 contacts the ground 40 so that the landing gear assembly 50 (in conjunction with other landing gear assemblies, if any) at least partially supports the aircraft.

[0008] Still referring to FIGURE 2, the illustrated landing gear assembly 50 accounts for squatting to minimize tire camber by angling the axle 60 downward relative to a horizonal plane when the landing gear is in a neutral, i.e., unloaded position. As used herein, the “unloaded position” corresponds to a landing gear position in which at least one tire of the landing gear contacts the ground without being subject to contact loading, i.e., the landing gear is not loaded by the aircraft on the ground. In the illustrated embodiment, axis 82 forms an angle 9 with axis 80. As shown in the figure, when angle 9 is greater than 90°, the wheel 62 has positive camber, which is represented by camber angle a.

[0009] When the aircraft is on the ground and supported by the landing gear, the squatting induced by the weight of the aircraft deflects the outer end axle 60 upward. This deflection reduces angle 0, which in turn reduces the camber angle a. The landing gear assembly 50 may be designed to account for squatting such that angle 9 is approximately 90° when the aircraft is on the ground and supported by the landing gear assembly 50. In this manner, the camber angle a is reduced to approximately 0°, i.e., the tire is positioned vertically, and uneven tire wear is reduced.

[0010] While the above-described configuration can generally provide a tire camber within a certain range, a single and fixed camber angle may not be optimal with respect to tire wear for all aircraft operating weights. Shims may be utilized to provide additional camber angle adjustment; however, the amount of adjustment provided by shims is limited. Further, the modifying shims to adjust a camber angle adjustment is imprecise and can require unduly long maintenance time.

[0011] The present disclosure is directed to embodiments of a landing gear assembly that provide for simple camber angle adjustment. More specifically, the disclosed configurations allow for more precise camber angle adjustments and also reduce the time required to make the adjustments.SUMMARY

[0012] The present disclosure provides examples of landing gear assembly with adjustable wheel camber. In an embodiment, the landing gear assembly includes a strut defining a first axis and an axle rotatably coupled to the strut about a second axis and defining a third axis. The landing gear assembly further includes a wheel rotatably coupled to the axle about the third axis and an adjustment assembly. The adjustment assembly is coupled to the strut and to the axle and is configured to provide selective adjustment of an angle between the first axis and the second axis.

[0013] In any embodiment, the adjustment assembly is an elongate member having a selectively adjustable length.

[0014] In any embodiment, a first end of the adjustment assembly is pivotally coupled to the strut.

[0015] In any embodiment, a second end of the adjustment assembly is pivotally coupled to the axle.

[0016] In any embodiment, the adjustment assembly comprises a turnbuckle.

[0017] In any embodiment, the turnbuckle comprises a first element pivotally coupled to the axle; a second element pivotally coupled to the strut; and an adjustment element threadedly coupled to the first element and to the second element.

[0018] In any embodiment, the first element is pivotally coupled to the axle by a first spherical bearing joint.

[0019] In any embodiment, the second element is pivotally coupled to the strut by a second spherical bearing joint.

[0020] In any embodiment, the adjustment assembly comprises an elongate rod and a first adjustable rod end pivotally coupled to one of the strut or the axle, wherein the first rod end is selectively adjustable to adjust a length of the adjustment assembly.

[0021] In any embodiment, the adjustment assembly further comprising a second adjustable rod end pivotally coupled to the other of the strut or the axle, wherein the second rod end is selectively adjustable to adjust the length of the adjustment assembly.

[0022] In any embodiment, the first adjustable rod end comprises a spherical bearing.

[0023] In any embodiment, the second adjustable rod end comprises a spherical bearing.

[0024] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.DESCRIPTION OF THE DRAWINGS

[0025] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0026] FIGURE 1 shows an isometric view of known landing gear assembly;

[0027] FIGURE 2 shows a cross-sectional view of the landing gear assembly of FIGURE 1 in an unloaded state, wherein the wheel is contacting the ground;

[0028] FIGURE 3 shows a cross-sectional view of an exemplary embodiment of a landing gear assembly with variable camber according to aspects of the presentdisclosure, wherein the landing gear assembly is in an unloaded state and the wheel is contacting the ground; and

[0029] FIGURE 4 shows a cross-sectional view of another exemplary embodiment of a landing gear assembly with variable camber according to aspects of the present disclosure, wherein the landing gear assembly is in an unloaded state and the wheel is contacting the ground.DETAILED DESCRIPTION

[0030] The detailed description set forth herein in connection with the appended drawings, where like numerals reference like elements, are intended as a description of various embodiments of the present disclosure and are not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result.

[0031] The following discussion provides examples of landing gear assemblies configured to enable wheel camber adjustment. More specifically, disclosed embodiments provide for more efficient and accurate camber adjustment to reduce uneven tire wear.

[0032] FIGURE S shows an embodiment of a landing gear assembly 100 formed in accordance with aspects of the present disclosure. The landing gear assembly 100 is similar to the landing gear assembly 50 shown in FIGURES 1 and 2, except that the landing gear assembly 100 is configured to provide adjustable tire camber.

[0033] The landing gear assembly 100 includes a shock strut with a piston 102 similar to the piston 52 shown in FIGURE 1. The piston 102 defines an axis 300 that is generally vertical when viewed from the front of the aircraft.

[0034] The piston 102 has a first lug 104 and a second lug 106 formed thereon, wherein the first lug 104 is positioned above the second lug 106. An elongate axle 110 is coupled at one end to the second lug 106 for rotational movement about an axis 304. In any embodiment, axis 304 is parallel to the centerline of the aircraft, i.e., is horizontal and extends in a longitudinal direction relative to the aircraft.

[0035] A wheel 120 is rotatably mounted to the axle 110 for rotation about axis 302. In any embodiment, axis 302 is perpendicular to and extends through axis 304. In any embodiment, axis 302 is offset from axis 304 and in a plane normal to axis 304. The axis 302 of the axle 110 forms an angle 0 with the axis 300 of the piston 102 when viewed from the front of the aircraft. The orientation of the axle 100 relative to the piston 102, i.e., angle 9, determines the camber of the wheel 120. In the illustrated embodiment, camber angle a is define by the equation:

[0036] (1) a = 0 - 90°

[0037] Still referring to FIGURE 3, an adjustment assembly 130. The adjustment assembly 130 selectively positions the axle 110 relative to the piston 102. That is, the adjustment assembly 130 maintains the position of the axle 110 relative to the piston 102 while enabling selective adjustment of angle 9.

[0038] In the illustrated embodiment, the adjustment assembly 130 includes a first elongate portion 132 with a first rod end 134 disposed at an end, and a second elongate portion 136 with a second rod end 138 disposed at an end. The first and second elongate portions 132 and 136 are coupled together by an adjustment element 140 to form a turnbuckle. By rotating the adjustment element 140, the length L of the adjustment assembly 130, i.e., the distance between the first rod end 134 and the second rod end 138, can be selectively increased or decreased.

[0039] As shown in FIGURE 3, the first rod end 134 is pivotally coupled to the lug 112 of the axle 110 about a pivot point 308, and the second rod end 138 is pivotally coupled to the lug 104 of the piston 102 about pivot point 306. In any embodiment, one or both of the first and second rod ends 134 and 138 includes a spherical bearing.

[0040] By extending and retracting the adjustment assembly 130, the distance between the first rod end 134 and the second rod end 138 increased and decreased, respectively, to drive rotation of the axle 110 about axis 304. As axle 110 rotates, angle 9 increases and decreases, which results in a corresponding increase or decrease of the camber angle a.

[0041] FIGURE 4 shows another embodiment of a landing gear assembly 200 formed in accordance with aspects of the present disclosure is shown. The landing gear assembly 200 is similar to the landing gear assembly 100 shown in FIGURE 3, except that the adjustment assembly 230 has a different configuration. For the sake of brevity, the adjustment assembly 230 will be described with the understanding that the othercomponents of the landing gear assembly 200 are similar to the previously described components of landing gear assembly 100, except as noted.

[0042] The adjustment assembly 230 includes an elongate body 232 with adjustable rod ends 234 and 236 coupled to opposite ends thereof. Each of the adjustable rod ends 234 and 236 threadedly engages the elongate body 232 so that the length L of the adjustment assembly 230 is selectively adjustable by rotating one or both rod ends.

[0043] In any embodiment, the adjustment element may include a single adjustable rod end. In any embodiment, the adjustment element may include a turnbuckle feature in conjunction with one or two adjustable rod ends. In any embodiment, the adjustment element may include a linkage. In any embodiment, the adjustment element may include any suitable locking feature. In any embodiment, the adjustment element includes any suitable configuration that enables selective adjustment of the length of the adjustment element.

[0044] Embodiments of the disclosed landing gear assembly provide selective adjustment of the wheel camber. By adjusting the camber so that the wheels are vertical, i.e., camber angle a=0°, uneven tire wear is minimized, thereby extending tire life and reducing the risk of a catastrophic tire failure.

[0045] In the foregoing description, specific details are set forth to provide a thorough understanding of representative embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-known process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein.

[0046] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also, in this regard, the present application may use the term “plurality” to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The term “about,” “approximately,” etc., means plus or minus 5% of the stated value.

[0047] It should be noted that for purposes of this disclosure, terminology such as “upper,” “lower,” “vertical,” “horizontal,” “fore,” “aft,” “inner,” “outer,” “front,”“rear,” etc., should be construed as descriptive and not limiting the scope of the claimed subject matter. Further, the use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings.

[0048] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0049] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure, which are intended to be protected, are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure as claimed.

Claims

9CLAIMSThe embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A landing gear assembly, comprising: a strut defining a first axis; an axle rotatably coupled to the strut about a second axis and defining a third axis; a wheel rotatably coupled to the axle about the third axis; an adjustment assembly coupled to the strut and to the axle, the adjustment assembly configured to provide selective adjustment of an angle between the first axis and the third axis.

2. The landing gear assembly of Claim 1, wherein the adjustment assembly is an elongate member having a selectively adjustable length.

3. The landing gear assembly of Claim 2, wherein a first end of the adjustment assembly is pivotally coupled to the strut.

4. The landing gear assembly of Claim 3, wherein a second end of the adjustment assembly is pivotally coupled to the axle.

5. The landing gear assembly of Claim 2, wherein a second end of the adjustment is assembly pivotally coupled to the axle.

6. The landing gear assembly of Claim 1, wherein the adjustment assembly comprises a turnbuckle.

7. The landing gear assembly of Claim 6, wherein the turnbuckle comprises: a first element pivotally coupled to the axle; a second element pivotally coupled to the strut; and an adjustment element threadedly coupled to the first element and to the second element.

8. The landing gear assembly of Claim 7, wherein the first element is pivotally coupled to the axle by a first spherical bearing joint.

9. The landing gear assembly of Claim 8, wherein the second element is pivotally coupled to the strut by a second spherical bearing joint.

10. The landing gear assembly of Claim 1, wherein the adjustment assembly comprises: an elongate rod; and a first adjustable rod end pivotally coupled to one of the strut or the axle, wherein the first rod end is selectively adjustable to adjust a length of the adjustment assembly.

11. The landing gear assembly of Claim 10, the adjustment assembly further comprising a second adjustable rod end pivotally coupled to the other of the strut or the axle, wherein the second rod end is selectively adjustable to adjust the length of the adjustment assembly.

12. The landing gear assembly of Claim 11, wherein the first adjustable rod end comprises a spherical bearing.

13. The landing gear assembly of Claim 12, wherein the second adjustable rod end comprises a spherical bearing.

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