Hinge structure

Abstract

The present invention relates to a spar structure (11) for connecting a movable part (4) to an aircraft. The structure is formed from a single continuous material form and a pair of continuous hinge lines (6, 7) extending through the form, the form defining a plurality of attachment / actuation brackets (10A to 10F).

Description

Technical Field

[0001] The invention relates to a method for producing an articulated connection between a movable surface of an aircraft and an aircraft structure. The invention also extends to an integrated articulated connection arrangement between a movable surface of an aircraft and an aircraft structure. Background Art

[0002] The movable structures on an aircraft include flaps, ailerons, tail planes and various other components that are arranged to direct or control the airflow over the aircraft structure when in use. As an example, the aileron is connected to the main wing structure by means of a hinge arrangement, allowing the aileron to rotate about a pivot to change the flow direction of the air.

[0003] Actuators (such as hydraulic pumps, worm gears, etc.) are used to pivot and move the movable structure about the hinge, thereby changing the aerodynamic performance and characteristics of the structure and the wing. This allows the aircraft to be controlled in flight through the movement of the structure.

[0004] Accurate alignment of the hinges with the connecting brackets that connect the movable structure to the wing is critical to allowing accurate and reliable control of the movable structure. Inaccuracies in hinge alignment can result in interference or restriction of movement, which is critical to the safe operation and flight of the aircraft.

[0005] To prevent any such problems, conventional movable surface hinges are manufactured by carefully drilling shafts or holes in each of the components that form the connection, and then assembling the components in a specialized manufacturing jig. This jig ensures precise alignment of all components as they are attached together to form the hinge and actuator attachment. Any misalignment of the hinge and bracket can be compensated for by further machining or by shimming or trimming the components.

[0006] However, current manufacturing methods have some disadvantages as they are labor intensive, resulting in high manufacturing costs, high scrap rates and slow manufacturing. The resulting manufacturing variations also result in extensive component rework and compromise.

[0007] Furthermore, inconsistencies in hinge manufacturing can hamper effective aircraft maintenance, making replacement of removable aircraft structures time-consuming, unreliable and expensive. Any misalignment when attempting to replace a hinged component will prevent replacement of that component and will require further labor-intensive work to align the hinge.

[0008] When applied to modern aircraft designs, the shortcomings of traditional manufacturing techniques are compounded as wingspans and the size of movable structures continue to increase. In addition, the rate at which aircraft maintenance must be performed (to allow the aircraft to operate economically) is high, and delays in maintenance can be a significant problem for aircraft operators.

[0009] The present inventors have devised a non-conventional hinge arrangement and corresponding manufacturing method that provides superior hinge connections for aircraft movable structures with greater precision and reliability, and that allows for economical and reliable field repairs of aircraft, including, for example, repairs on airfields. Summary of the invention

[0010] Aspects of the invention are set out in the accompanying claims.

[0011] Viewed from a first aspect, there is provided a spar structure for connecting a movable component to an aircraft, the spar structure comprising a continuous form of material defining a plurality of attachment / actuation brackets and a pair of continuous hinge lines extending through the form.

[0012] Thus, the spar structure described herein is formed as an integral part or component that is a single continuous component rather than a composite structure composed of multiple separate components. Due to the need for precise alignment of each bracket, complex jigs are traditionally used that include scraping or shimming to achieve the precision required for hinge alignment.

[0013] Forming the spar from a single body of material is counterintuitive because of the industry perception and accepted practice that the fixture arrangement provides the greatest tolerance control.

[0014] According to the invention described herein, the pair of continuous hinge lines define a reference for attaching / actuating the position of the bracket, i.e., instead of manufacturing the bracket and positioning it extremely precisely around the hinge lines, the inventors adopted the opposite approach, i.e., using the hinge lines as references and forming the bracket around these two reference lines.

[0015] Although extensive machining is required, the material removed can be recycled and computer numerical control machines (CNC machines) can be easily programmed to continuously form the spar structure according to a predetermined program.

[0016] Furthermore, the strength and stiffness of the structure can be optimized and the structure can be designed without areas that would otherwise be stress concentrators. Still further, no (or very few) rivets, connectors or other couplings are required between the bracket and the spar. The bracket and spar become completely integrated.

[0017] Advantageously, one of the pair of hinge lines may intersect a first set of the attachment / actuation brackets and a second of the hinge lines may intersect a second set of the attachment / actuation brackets. Adjacent brackets need not serve the same purpose and structural redundancy may be built into the spar should either bracket fail in any way.

[0018] In particular, the first set of attachment / actuation brackets may be brackets arranged to pivotably mount the movable component to the aircraft structure. This defines a line or axis about which the movable component (eg an aileron) rotates.

[0019] Similarly, the second set of attachment / actuation brackets may be brackets arranged to couple the spar structure to the actuator. An actuator (e.g. a linear actuator or the like) may thus be coupled to the spar structure. Movement of the second set of brackets by means of the actuator causes the spar (and the movable component) to rotate about the above-mentioned axis or hinge line.

[0020] Thus, by virtue of the pair of hinge lines extending through the form and intersecting the two sets of brackets, the spar may be both securely coupled to a wing (for example) and simultaneously permitted to rotate in response to selective control by actuators.

[0021] Advantageously, each hinge line may define a cylindrical hole through each attachment / actuation bracket intersecting the pair of hinge lines. Thus, each bracket intersecting a hinge line will be perfectly aligned with the longitudinal hinge line passing through the spar.

[0022] The spar may be formed from any suitable structural shape. In one arrangement, the structure may include an outer generally U-shaped body. The attachment / actuation bracket may be formed within the generally U-shaped body. Thus, the U-shaped body provides structural rigidity, and the brackets arranged internally increase rigidity. The open face of the U-shaped body conveniently provides a surface through which the brackets can extend. Thus, a compact shape may be provided.

[0023] The spar may be arranged to be coupled to the movable part itself by any suitable arrangement. For example, this may be done by conventional rivets, glue or other fastening means. The spar may then be formed as a single component and then selectively coupled to the movable part. Alternatively, the spar may be permanently connected to the movable part, making maintenance simpler.

[0024] Viewed from another aspect of the invention described herein, there is provided an aircraft structure arranged to be connected to an aircraft via a hinge and comprising a spar structure as described herein.

[0025] The aircraft structure may be selected from the following non-exhaustive list: ailerons, flaps, rudders or wing components.

[0026] It will be appreciated from the present teachings that the structure may advantageously be machined from a single block or billet of material. In an alternative approach, the spar may be formed using additive manufacturing techniques, for example one of the following techniques may be used:

[0027] Powder Bed Fusion

[0028] Direct Metal Laser Sintering (DMLS)

[0029] Electron Beam Melting (EBM)

[0030] Selective Laser Melting (SLM)

[0031] Selective Laser Sintering (SLS)

[0032] Direct wire deposition

[0033] Direct Metal Powder Deposition

[0034] Viewed from another aspect, there is provided a method of manufacturing a wing spar structure for connecting a movable component to an aircraft, the wing spar structure comprising a continuous material form defining a plurality of attachment / actuation brackets and a pair of continuous hinge lines extending through the form, the method comprising the steps of:

[0035] (A) drilling a pair of elongated holes in the block or blank of material to define the pair of continuous hinge lines; and

[0036] (B) machining the block or blank of material according to a predetermined machining profile to form a spar structure around the pair of continuous hinge lines.

[0037] Machining the holes before machining the spar is advantageous in that the all important hinge line becomes the reference for the part. The form of the spar structure can be built around the hinge line to maintain its accuracy and integrity.

[0038] The bores or holes may be formed by any suitable drilling technique. Advantageously, a deep hole drilling process may be used. For example, a gun drilling process may be used to provide a highly accurate bore. Advantageously, a gun drilling process allows for the formation of long holes having a high aspect ratio. This allows the pair of holes to be drilled along the length of a relatively long stock of material prior to machining the spar form.

[0039] In order to further increase the accuracy of the drilling process, the material block or blank can be rotated during the drilling process in the opposite direction relative to the rotation direction of the drilling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0041] Figure 1 A schematic diagram showing a movable structure of an aircraft wing;

[0042] Figure 2 A pivot and actuator arrangement for a movable structure is shown;

[0043] Figure 3The positions of the wing ailerons and the actuating and hinge brackets are shown;

[0044] Figure 4 The integrated spar and aileron are shown;

[0045] Figure 5 Shows Figure 4 A close-up view of the integrated spar; and

[0046] Figure 6 The blank, integrated spar and pivot line are shown.

[0047] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and described in detail herein. However, it should be understood that the attached drawings and detailed description are not intended to limit the present invention to the specific forms disclosed, but the present invention will cover all modifications, equivalents and alternatives that fall within the spirit and scope of the claimed invention.

[0048] It will be appreciated that the features of the aspects of the invention described herein may be used conveniently and interchangeably in any suitable combination.It will also be appreciated that the invention encompasses not only each individual embodiment, but also the combination of embodiments that have been discussed herein. DETAILED DESCRIPTION

[0049] Figure 1 is a schematic end view of an aircraft wing 1 , seen in cross section towards the fuselage of the aircraft. The wing comprises a leading edge 2 and a trailing edge 3 . Figure 1 An example of a movable structure on a conventional aircraft is shown. The structure shown is an aileron 4 which is movable about a pivot near the trailing edge of the main wing box 5. The arrows show that the aileron can then move about the pivot. The movement causes the distal portion of the aileron relative to the pivot to move in an arc, which in the case of the aileron allows the aircraft to roll and turn.

[0050] Figure 1 Only 1 position of a movable component on an aircraft structure is represented. Other examples include flaps, tail planes, tail rudders, and even landing gear doors. It will be appreciated that the arrangements and methods described herein can be applied to any articulated arrangement for an aircraft structure.

[0051] Figure 2 yes Figure 1 A cross section of the pivot connection of the aileron in FIG. The aileron 4 is rotatably mounted to the pivot. As described below, the pivot extends along the aileron. Movement of the aileron 4 about the pivot causes the aileron to move in an arc in the direction of the arrow.

[0052] The aileron is provided with a second pivot 7 which is coupled to an actuator 8 which comprises an extendable rod or arm 9 which can be extended or retracted in the direction of the arrows shown. The actuator 8 and arm 9 can be any suitable combination for use on an aircraft. An example is a hydraulic pump driving a threaded rod. Thus, rotation of the drive causes movement of the rod. Because the pivots 6 and 7 are offset, movement of the rod 9 causes the aileron to move about the pivot 6. The actuator and rod are housed in the wing box 5.

[0053] Figure 2 is a cross section of a pivot and actuator arrangement. In order to support the aileron along its length (which on some aircraft may be over 3 meters long), the hinge arrangement and actuator attachments need to be located at multiple points along the aileron / wing box. Figure 3 A 6 point hinge connection is shown.

[0054] exist Figure 3 In FIG. 5 , the aileron 4 is connected to the wing box 5 at 6 discrete points 10A, 10B, 10C, 10D, 10E and 10F. An actuation point is not required at every location, so, for example, the actuation points may be locations 10B and 10D, and the remaining locations may be hinge points or pivot points. This advantageously allows redundancy in the hinge and further supports the aileron equally along its length if one connection fails.

[0055] As discussed above, the length of the aileron may exceed 3 meters, so accurate alignment of the pivot axis extending through each of the connection points 10A to 10F is critical to accurate operation of the aileron.

[0056] Traditionally, this precise alignment is achieved by positioning each bracket forming the pivot 6 connection and the actuator pivot 7 connection in a specially manufactured fixture before assembly. Then, the shaft can be passed through each hole in the bracket to form the elongated pivot axis of the pivot 6 and pivot 7.

[0057] However, as also mentioned above, this is very time consuming and requires skill to meet the required interchangeability (ICY) tolerances. Trimming and shimming techniques are used to ensure ICY compliance in conventional arrangement structures.

[0058] Conventional connection arrangements such as those described above advantageously allow for individual hinge and actuator attachment brackets to be individually removed and repaired during service life (using appropriate fixtures to re-implement the hinge lines). Disadvantageously, these arrangements are labor-intensive assembly tasks, resulting in high recurring costs, high part counts, and manufacturing tolerance variations that are multiplied by the number of individual parts.

[0059] Details of alternative coupling arrangements will now be described.

[0060] Figure 4 An integrated and continuous hinge joint arrangement according to the invention described herein is shown.An integrated or continuous front spar 11 for the aileron 4 is provided.

[0061] The term integrated / continuous is intended to refer to a component that is formed as a single material form. Specifically, the integrated spar 11 can be formed by machining a single material blank to form the form of the spar and each hinge or actuator attachment that allows the aileron to be coupled to the wing box (at Figure 4 ) and is also actuated to cause movement of the aileron relative to the wing box.

[0062] Alternatively, the integrated spar 11 may be formed using additive manufacturing techniques to form the spar as a single, undivided component incorporating a rigid outer body supporting the plurality of hinges and actuator brackets.

[0063] Figure 4 The separate integrated spar 11 and aileron are shown. However, in use, the spar is coupled to the front edge 12 (leading edge) of the aileron 4. Figure 4 The arrangement structure in is constructed to replicate Figure 3 The locations of the hinge and actuator attachment brackets shown in , ie connections 10A to 10F, and one further hinge location is added. The integrated spar 11 is a single component and may be coupled to the aileron leading edge in any suitable manner.

[0064] Figure 5 The integrated spar 11 at one end is shown in more detail. It can be seen that the hinge and actuator brackets replicate the Figure 3 The connections 10A, 10B and 10C are shown in FIG.

[0065] Figure 5 Also shown is the spatial separation of the two hinge lines 6 and 7. Pivot line 6 represents the pivot line of the aileron, while pivot line 7 represents the pivot axis to which the actuator is connected. It will be appreciated that the shaft passing through pivot line 7 (connecting the actuator to the integral spar) will itself rotate about pivot line 6 when actuation occurs.

[0066] Any suitable configuration of hinge brackets and actuation brackets may be positioned along the length of the integral spar, as in a conventional connection arrangement.

[0067] As mentioned above, the integrated spar 11 can advantageously be formed from a single billet of material. A billet of aluminum (as an example) can be machined using a suitable CNC milling machine to produce the integrated spar. The machined material can be recycled to optimize material usage, and the spar geometry can also be optimized for stiffness and strength.

[0068] Advantageously, this integrated spar arrangement overcomes the disadvantages of manufacturing the current hinge and actuator attachment brackets assembled together by machining all required attachment brackets in a single bracket. The required attachment brackets (also known as lugs / clevises) are then machined as an integrated feature. This process eliminates the requirement for complex drilling / reaming supports, which would be normal practice if the process were reversed.

[0069] Furthermore, the arrangement reduces assembly time and associated costs to achieve the required hinge line tolerances.

[0070] Thus, a fully integrated spar is provided in accordance with the invention described herein. It will be appreciated that the invention extends to a method of manufacturing such an integrated spar arrangement from a single billet of material or using additive manufacturing techniques.

[0071] The present inventors have further determined that the above method allows for a further advantageous manufacturing method to be used, as will be described below.

[0072] Specifically, prior to machining the blank to form the brackets and structures of the integrated spar, a high precision hinge or pivot line can be achieved by pre-drilling the brackets and structures in the blank prior to the machining operations. Figure 6 Provide explanation.

[0073] Integrated spar 11 Figure 6 1 and 2. The wing spar 11 is shown in the surrounding blank 12. The blank is a continuous block of material from which the spar 11 can be machined, as described above.

[0074] Advantageously, prior to machining to form the spar, a non-traditional method can be employed to first drill out the spar that will be formed. Figure 6 The elongated holes or bores for the pivot axes 6 and 7 shown in FIG. Once the bores have been formed, the integrated spar can be machined. In practice a multi-stage process is performed: first the pivots are formed, then the structure is formed around the pivot axes.

[0075] This method provides a highly accurate and continuous pivot line around which the bracket can be created without compromising the accuracy of the pivot line. Figure 6 As shown in , the drilled holes do not need to extend through the entire length of the blank; they only need to extend as far as the last bracket using the pivot line. This method can be applied to all aircraft movable surfaces that require tight hinge line tolerances.

[0076] Advantageously, the boreholes forming the pivot axes 6, 7 can be formed using a deep drilling process, such as a gun drilling process. This allows forming boreholes with a high length-to-diameter ratio, like the base with the pivot axis in a hinge for a movable structure of an aircraft.

[0077] The gun drilling process involves supplying coolant along the center of the drill bit, which acts to both cool the cutting surface and carry chips (waste material from the cutting zone) back along the drilled hole and away from the component. Extremely deep holes can be drilled.

[0078] Advantageously, to further improve the accuracy of the pivot axis, the blank can be counter-rotated about the gun drill rotation axis. This advantageously maintains extremely accurate drilling and improves the drilling operation. In such a manufacturing process, the blank can first be positioned in a fixture that allows rotation about the gun drill axis to form the first pivot axis 6, and then the same process can be repeated to form the second pivot axis 7, namely by rotating the blank about the pivot axis 7 during the drilling process. In each case, the pivot axis is used as a reference for the blank to rotate about. Specifically, the use of the counter-rotation method allows for more than 1 / 10 th mm tolerance, which is desirable in the current application.

[0079] The manufacturing process and resulting integrated spar provides a single discrete hinge component with a highly accurate pair of hinge lines to receive the hinge bracket and actuation bracket of an aileron (or other movable hinged structure). The fact that no bracket alignment is required means that when attached to a component such as an aileron, the aileron can be replaced with high precision, minimal tooling and in an efficient manner. This not only provides efficient routine maintenance of the aircraft, but also conveniently allows for rapid repairs outside of a hangar, such as at an airfield or the like. This arrangement does not require complex and expensive fixtures and provides a component that can be easily recycled.

[0080] In order to safely mount the component, it is necessary that the component reach the same temperature as the wing (to avoid any thermal expansion problems) and then be mounted.

[0081] It will be appreciated that the invention described herein extends to a moveably articulated structure for an aircraft incorporating the integrated spar described herein, and in particular to an aircraft aileron including a leading edge integrated spar described herein.

Claims

1. A spar structure for connecting a movable component to an aircraft, the spar structure comprising a continuous material form and a pair of continuous hinge lines extending through the form, the form defining a plurality of attachment / actuation brackets, wherein the spar structure is formed by a method comprising the steps of: (A) drilling a pair of elongated holes in the block or blank of material to define the pair of continuous hinge lines; and (B) machining the block or blank of material according to a predetermined machining profile to form a spar structure around the pair of continuous hinge lines, in, The spar structure comprises an outer generally U-shaped body, and wherein the attachment / actuation bracket is formed within the generally U-shaped body.

2. The spar structure according to claim 1, wherein: A first hinge line in the pair of continuous hinge lines intersects a first group of attachment / actuation brackets in the attachment / actuation brackets, and a second hinge line in the pair of continuous hinge lines intersects a second group of attachment / actuation brackets in the attachment / actuation brackets.

3. The spar structure according to claim 2, wherein: The first set of attachment / actuation brackets are brackets arranged for pivotably mounting the movable component to an aircraft structure; and The second set of attachment / actuation brackets are brackets arranged to couple the spar structure to actuators.

4. The spar structure according to any one of claims 1 to 3, wherein: Each of the pair of continuous hinge lines defines a cylindrical hole through each of the attachment / actuation brackets that intersect the pair of continuous hinge lines.

5. A spar structure according to any one of claims 1 to 3, comprising a coupling arrangement arranged for connecting the spar structure or a movable part.

6. An aircraft structure arranged to be connected to an aircraft via a hinge and comprising a spar structure according to any one of claims 1-5.

7. The aircraft structure according to claim 6, wherein the aircraft structure is selected from an aileron, a flap, a rudder or a wing component.

8. A method of manufacturing a spar structure according to any one of claims 1 to 5, comprising the step of machining the structure from a block or billet of material.

9. A method of manufacturing a wing spar structure for connecting a movable component to an aircraft, the wing spar structure comprising a continuous material form and a pair of continuous hinge lines extending through the form, the form defining a plurality of attachment / actuation brackets, the method comprising the steps of: (A) drilling a pair of elongated holes in the block or blank of material to define the pair of continuous hinge lines; and (B) machining the block or blank of material according to a predetermined machining profile to form a spar structure around the pair of continuous hinge lines, in, The spar structure comprises an outer generally U-shaped body, and wherein the attachment / actuation bracket is formed within the generally U-shaped body.

10. The method according to claim 9, wherein: The process of drilling the pair of elongated holes is carried out by means of a deep hole drilling process.

11. The method according to claim 10, wherein: The deep hole drilling process is a gun drilling process.

12. The method according to claim 10 or 11, wherein: In the deep hole drilling process, the material block or blank is rotated in the opposite direction relative to the rotation direction of the deep hole drilling process.

13. An aircraft wing comprising a spar structure according to any one of claims 1 to 5 and a movable component.

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