Tolerance-compensating fastening arrangement for fastening a component to a structure

A tolerance-compensating fastening arrangement for fastening a component to a structure includes a male fastener having a fastening bolt having a serrated outer profile; and a female fastener having a socket base arranged therewithin movable along a horizontal plane and having a conical funnel to receive the bolt such that horizontal tolerances between the male and female fasteners are compensable by movement of the socket base actuated through contact of the bolt with an inner surface of the funnel; and a socket jaw arranged on the socket base and having several jaw segments arranged circumferentially around a vertical axis to form a central jaw opening configured to receive the bolt through the funnel, the jaw segments configured movable radially with respect to the vertical axis to adjust a size of the jaw opening to retain the bolt along the vertical axis via contact of the serrated inner and outer profiles.

FIELD OF THE INVENTION

The present invention pertains to a tolerance-compensating fastening arrangement for fastening a component to a structure.

Although it can be used in many applications, the present invention and the problems underlying it are explained in greater detail in relation to passenger aircraft. However, the methods and devices described can likewise be used for affixing a broad variety of components to various structures in different applications. For example, the invention may be used to fasten components to different vehicle structures, e.g. road vehicles, rail vehicles, watercraft and aircraft.

BACKGROUND OF THE INVENTION

The fixation of an object relative to another object is conventionally achieved by a threaded rod affixed to one object and a washer and nut coupled to the other object. In order to provide a particular distance between the objects, one or more spacers are usually employed. However, when installing a plurality of objects along a line, each of the objects has to be affixed with a respective spacer. If a certain tolerance is further to be levelled out, different spacers have to be used for each object. The installation of such a plurality of objects, therefore, becomes cumbersome and time-consuming.

For instance, in a passenger cabin of an aircraft the ceiling above passenger seats may consist of a plurality of different panels, including panels with reading lights, control buttons, security signs and covers for oxygen mask containers. Likewise, a plurality of modules including such panels may be installed when building the interior of the aircraft. Each of these modules or other components having one or more panels to form the ceiling of the passenger cabin may be affixed directly to the primary structure, such as a frame, or an installation bar provided on the primary structure. Alternatively, a specific arrangement of such components may be preassembled outside the aircraft fuselage to form a ceiling module, which may then be moved into the fuselage as one integrated system and mounted to the primary structure as a whole. In both instances however, a configuration of the primary structure or installation structure may vary due to tolerances affecting positions, orientations and/or shapes of components relative to the inside of the fuselage. Thus, if the ceiling would be installed to the primary structure with the same fixation means, each component or portion might be installed at different positions and/or orientations, which is undesirable. The use of different sized spacers, on the other hand, is time-consuming, since the correct spacer has to be found during installation and installed for each module or panel.

Examples for fixing interior components to an aircraft structure can be found, for example, in EP 3 254 967 A1 and EP 3 254 951 A1.

BRIEF SUMMARY OF THE INVENTION

Against this background, aspects of the present invention may relate to finding simple yet effective solutions for fastening a component to a structure taking tolerances into account.

According to an aspect of the invention, a tolerance-compensating fastening arrangement for fastening a component to a structure is provided. The fastening arrangement comprises a male fastener comprising a fastening bolt having a serrated outer profile with a plurality of ridges arranged one after the other along the fastening bolt, each ridge running circumferentially around an outer surface of the fastening bolt. The fastening arrangement further comprises a female fastener, which comprises a socket base arranged within the female fastener movable along a horizontal tolerance compensation plane and having a conical funnel configured to receive the fastening bolt such that horizontal tolerances between the male fastener and the female fastener are compensable by movement of the socket base within the female fastener, the movement being actuated through contact of the fastening bolt with an inner funnel surface of the conical funnel; and a socket jaw arranged on the socket base and comprising several jaw segments arranged circumferentially around a vertical tolerance compensation axis such as to form a central jaw opening configured to receive the fastening bolt through the conical funnel of the socket base, each jaw segment having a serrated inner profile with a plurality of ridges arranged one after the other along the vertical tolerance compensation axis, the jaw segments being configured movable radially with respect to the vertical tolerance compensation axis to adjust a size of the jaw opening to retain the fastening bolt along the vertical tolerance compensation axis via contact of the serrated inner profile and the serrated outer profile and thereby compensate vertical tolerances between the male fastener and the female fastener.

According to a further aspect of the invention, an aircraft or spacecraft has a fastening arrangement according to an embodiment of the invention.

Thus, one idea of the present invention is to provide fastening means with integrated tolerance compensation in all three dimensions. This means that relative positions between the component and the structure may deviate from prescribed dimensions to a certain extent, e.g. up to 1 cm, in each coordinate direction. These deviations are then compensated by the fastening system. The present fastening system is self-finding and thus automatable in the sense that the system finds the mounting configuration on its own due to the fact that the fastening bolt moves the socket base automatically in the horizontal tolerance compensation plane by the required distance just by entering the conical funnel and thereby making contact with the inner funnel surface (tolerance compensation along, e.g., x- and y-coordinates). The fastening bolt may then be retained within the female fastening member at a certain penetration depth (tolerance compensation in, e.g., z-direction). It should be noted that the tolerances between the component and the structure are not eliminated after the connection is formed. In fact, the component and the structure both still hold their individual reference positions after the connection is closed. However, the connection via male fastener and female fastener compensates these tolerances in a very convenient way.

In sum, aspects of the present invention provide the opportunity to affix a component to a structure in a tolerance compensating way, which is reliable and which can be fully automatized. Manual installation steps can thus be avoided. As a result, aspects of the invention may save installation time and costs significantly.

According to an embodiment of the invention, the socket jaw may comprise at least three identical jaw segments.

Three jaw segments may be an optimal compromise between effectiveness and robustness of the fastening system. It is to be understood however that also more than three jaw segments may be utilized, e.g. four, five or even more segments, which may or may not be identical. In principle, also solutions based on merely two jaw segments may be suitable for certain applications. Also in this case the jaw segments may be configured identical.

According to an embodiment of the invention, each ridge of the serrated outer profile of the fastening bolt may have an inclined top face and a horizontal bottom face. The serrated inner profile of the jaw segments may be complementary serrated to the serrated outer profile of the fastening bolt.

This arrangement of an inclined top surface and a horizontal bottom surface may be used, for example, to provide a self-closing and/or self-locking snap-in arrangement, where the fastening bolt may be pushed into the jaw opening between the jaw segments as a far as required—thereby repeatedly pushing the jaw segments radially outwards with the inclined top faces of the ridges—and finally snap into a position, in which the ridges of the fastening bolt engage the corresponding ridges on the jaw segments. As long as any radial movement of the jaw segments is prohibited after that, the bolt will thus be locked within the socket jaw, as the horizontal bottom faces of the ridges block any movement of the fastening bolt in the backward direction.

According to an embodiment of the invention, the inclined top face may have an inclination angle of 60°.

However, it will be clear to the person of skill that other configurations may have advantages in certain application, e.g. configurations having inclination angles larger or smaller than 60°. In principle, the inclination of the individual ridges may even vary along the fastening bolt. The serration may follow a certain standard, e.g. a standard 60° serration according to NSA 509.03 with a pitch of 1 mm between the individual ridges. Such a serration is simple to manufacture with standard tools.

According to an embodiment of the invention, the female fastener may further comprise a base plate, on which the socket base is slidably arranged. The female fastener may further comprise a cover plate above the socket jaw. The socket base may comprise a wedged turning surface and the socket jaw may comprise a complementary wedged turning surface. The socket jaw may slidably rest with the complementary wedged turning surface on the wedged turning surface of the socket base such that the socket jaw is pressable against the cover plate by relative rotation of the socket base and the socket jaw at the wedged turning surfaces around the vertical tolerance compensation axis to block movement of the socket base and the socket jaw with respect to the base plate and the cover plate.

The base plate and the cover plate may both be affixed in position, e.g. firmly attached to a bracket or similar that is connected to the structure, and may thus together form a retaining or support structure of the female fastener. By means of the wedged turning surfaces a simple and yet effective closing mechanism is provided for the fastening system that makes it possible to fix the positions of male and female fasteners relative to each other, in particular within the horizontal tolerance compensation plane, by pressing the socket jaw against the cover plate (force fit) and thereby also blocking movement of the socket base along the horizontal plane.

In principle, both components, that is, the socket jaw and the socket base, may be locked within the respective open and/or closed position by a suitable mechanism. For example, the wedged surfaces may further be configured with an additional serration, which may be orientated and/or configured such that relative (sliding) movement of the wedged surfaces is only possible in one direction of rotation.

According to an embodiment of the invention, the cover plate may have a serrated lower surface and the socket jaw may have a serrated upper surface complementary formed to the serrated lower surface of the cover plate.

In this embodiment, the serrated faces of the cover plate and the socket jaw may additionally help to block any relative, e.g. sliding, movement between the socket jaw and the cover plate. For example, if such sliding movement can be blocked merely on basis of friction in the closed state (without or with minor loads), then the additional serration may be omitted. However, under certain circumstances the additional serration may help to further secure the system in the closed state.

According to an embodiment of the invention, the socket jaw may further comprise a jaw bowl, the jaw bowl having a concave bearing surface and the jaw segments having a convex bearing surface configured to slidably mount the jaw segments within the jaw bowl such that angular tolerances between the male fastener and the female fastener are compensable by sliding movement of the fastening bolt together with the jaw segments within the jaw bowl.

The system thus not only provides an interface for blind and automated installation of components with integrated tolerance compensation in three perpendicular directions, namely x-, y- and z-direction. In addition, angular tolerances may be compensated to some extent, e.g. several degrees. To this end, the socket jaw and the fastening bolt together form a rotary joint inspired by a ball-and-socket joint type. The stationary part of the joint is formed by the concave jaw bowl, which may have, for example, a basically (at least partly) spheroid concave surface. The movable part of the joint is formed by the fastening rod engaging the jaw segments, wherein the latter may have a basically (at least partly) spheroid convex surface. The basic shape of the convex surface may principally correspond to the shape of the concave surface of the stationary part so that both connection parts may be brought in contact with each other at the bearing surfaces. The touching convex and concave surfaces may then move in a sliding manner with respect to each other, similar to a ball-and-socket connection, at least in a limited angular range relative to the vertical tolerance compensation axis, e.g. up to several degrees, e.g. between 0° and 5° or 10°.

It should be noted in this respect that the sliding movement of the jaw segments within the jaw bowl also provides movement of the jaw segments in radial direction for adjusting the size of the jaw opening.

According to an embodiment of the invention, the concave bearing surface of the jaw bowl and the convex bearing surface of the jaw segments may be configured basically spheroid.

Basically (at least partly) spheroid bearing surfaces represent one particularly simple and elegant example for a system of concave and convex surfaces, which is based on classical ball-and-socket joints.

However, according to an alternative embodiment of the invention, the concave bearing surface of the jaw bowl and the convex bearing surface of the jaw segments may be configured basically conical.

Thus, instead of a ball-like configuration, also other shapes for the concave and convex bearing surfaces may be conceived. A conical shape provides one such alternative example.

According to an embodiment of the invention, the curvature of the concave bearing surface of the jaw bowl corresponds to the curvature of the convex bearing surface of the jaw segments.

This enables the implementation of a smooth contact between the two movable parts, thereby reducing the inner friction within the “joint”.

According to an embodiment of the invention, the female fastener may comprise a cover plate above the socket jaw and the socket jaw may comprise a spring element configured to resiliently preload the jaw segments against the cover plate.

Such a spring element may prohibit any unwanted movement of the jaw segments along the vertical tolerance compensation axis, for example after the fastening arrangement is locked in position. Otherwise, minor movements of the jaw segments might lead to vibrations and/or fatigue problems, e.g. during flight of an aircraft, in which the components are installed. In the present embodiment, the jaw segments are constantly pushed down by the spring element with a suitable predefined force such that any further movements after closing the system are suppressed.

According to an embodiment of the invention, the socket jaw may further comprise a retainer ring around the vertical tolerance compensation axis. The retainer ring may be configured with a sliding track of variable radius for each jaw segment, in which the respective jag segment is slidably mounted to facilitate radial movement of the jaw segment with respect to the vertical tolerance compensation axis by rotation of the retainer ring around the vertical tolerance compensation axis.

The retainer ring thus provides a very simple to use yet effective solution to facilitate radial movement of the jaw segments in a controlled and guided way. In one particular example, three identical jaw segments may be provided, each of which may be mounted in an associated sliding track within the retainer ring. By turning the retainer ring by 90° (for example) each jaw segment is moved along the sliding track and thereby moved radially either inwards or outwards depending on the direction of rotation. The range of the radial movement can be configured accordingly such that the jaw opening can be opened and closed around the fastening bolt appropriately.

According to an embodiment of the invention, each sliding track may be configured with a lock slot at a radially inward end position and each jaw segment may be configured with a lock bolt complementary formed to the lock slot to lock the jaw segments at the radially inward end position within the retainer ring.

The embodiment thus provides a simple locking mechanism that allows one to fixate the fastening arrangement along the transverse tolerance compensation axis by simple turn of the retainer ring. To this end, the retainer ring may have a control surface, a handle or similar at an radially outward portion by means of which a user may grab and turn the retainer ring. Alternatively or additionally, it is of course possible to provide an actuation system to avoid the need for manual access.

According to an embodiment of the invention, the retainer ring may be configured to lock the jaw segments by shifting along the vertical tolerance compensation axis.

Thus, operation of the retainer ring may involve two steps: first, the ring may be turned, e.g. by 90°, in order to close the jaw opening and thus engage the fastening bolt with the jaw segments, thereby fixating the system along the vertical tolerance compensation axis. In a second step, the ring may then be shifted either downwards or upwards along the vertical tolerance compensation axis to lock the jaw segments in their current positions and thus lock the system in vertical direction.

According to an embodiment of the invention, the component may comprise several male fasteners and the structure may comprise corresponding female fasteners.

For example, an integrated ceiling module for an aircraft may be affixed to a primary fuselage structure by utilizing several of the present fasteners per frame, that is, per transverse circumferentially running stiffening element of the fuselage. In one particular example, six fasteners may be used to fasten the ceiling module to one such frame. The aircraft may comprise 50 frames so that overall 300 fasteners are required to fix the ceiling module to the aircraft structure. Despite this exemplary large number of individual fasteners, the component (the ceiling module) may still be installed within a few hours due to the self-finding and automatized tolerance compensating nature of the present system. In principle, it is possible to employ several different embodiments of male and female fasteners at the same time, e.g. because certain fastener solutions may be more suitable for fixing certain aircraft parts.

The invention will be explained in greater detail with reference to exemplary embodiments depicted in the drawings as appended.

DETAILED DESCRIPTION

Some of the components, elements and assemblies as disclosed hereinforth may be fabricated using free form fabrication (FFF), direct manufacturing (DM), fused deposition modelling (FDM), powder bed printing (PBP), laminated object manufacturing (LOM), stereolithography (SL), selective laser sintering (SLS), selective laser melting (SLM), selective heat sintering (SHS), electron beam melting (EBM), direct ink writing (DIW), digital light processing (DLP) and/or additive layer manufacturing (AM). Those techniques belong to a general hierarchy of additive manufacturing (AM) methods. Often termed as 3D printing, those systems are used for generating three-dimensional objects by creating a cross-sectional pattern of the object to be formed and forming the three-dimensional solid object by sequentially building up layers of material. Any of such procedures will be referred to in the following description as AM or 3D printing without loss of generality. AM or 3D printing techniques usually include selectively depositing material layer by layer, selectively fusing or solidifying the material and removing excess material, if needed.

3D or AM techniques may be used in procedures for building up three-dimensional solid objects based on digital model data. 3D/AM employs an additive process where layers of material are sequentially built up in different shapes. 3D/AM is currently used for prototyping and distributed manufacturing with multiple applications in engineering, construction, industrial design, automotive industries and aerospace industries.

FIG.1shows a cross-sectional view of an aircraft100with a fastening arrangement10according to an embodiment of the invention.

The aircraft100depicted inFIG.1may be a passenger plane, for example. A fuselage of a typical passenger plane consists of a rigid framework of stiffening elements that is covered by a skin. The framework comprises a series of frames/formers bent into a circumferential direction according to the shape of the fuselage cross section and a plurality of longitudinal stringers/longerons that are joined to the frames. Inside the fuselage, a plurality of cross beams for supporting a cabin floor may be arranged one after the other in the longitudinal direction of the aircraft100, each cross beam extending in a cross direction and being attached on both ends to the frames and/or stringers. The cross beams may further be supported by vertical struts and so on. All of these components are part of a so-called primary structure102, which provides the elements for stiffing the overall structure of the aircraft100. The components of the primary structure102are usually fastened to each other by rivets or similar means in the course of a major component assembly of the aircraft100.

One approach for installing a cabin ceiling in such an aircraft100may include preassembling an integrated ceiling module or component101outside the fuselage of the aircraft100. Such a ceiling module may comprise amongst others the corresponding ceiling substructure of pipes, supply lines, cables, conduits, compartments, structural connectors and so on. In a second installation step, the ceiling module101may then be moved into the fuselage of the aircraft100as a whole and fastened to the primary structure102of the aircraft100in one run by means of a fastening arrangement10comprising a multitude of male fasteners1and corresponding female fasteners2. The male fasteners1may be provided on the ceiling component101and the female fasteners2may be provided on the primary structure102of the aircraft100, e.g. several on each frame (cf.FIG.1). It is to be understood however that male and female fasteners1,2may be interchanged and that at least some of the male fasteners1may be provided as well on the structure102and the corresponding female2fasteners accordingly on the component101. In order to install the component101on the structure102, the component101may be moved by a jig/tool (not shown in the figures), which may position the respective male fasteners1relative to the female fasteners2and move the male fasteners1simultaneously and/or successively into the female fasteners2to close the connection (cf. arrows inFIG.1).

The position and alignment of the fasteners1,2may now vary due to tolerances of the aircraft parts, which in turn may affect positions, orientations and/or shapes of installed ceiling parts relative to the inside of the fuselage in case these tolerances are not compensated. For example, ceiling panels may be installed at different heights, i.e. different distances to a cabin floor, which is undesirable, since passengers and aircraft operators prefer a flush ceiling. With references toFIG.2ff., various embodiments of fastening arrangements10will now be described that may be used in the system ofFIG.1to automatically compensate such tolerances.

FIGS.2to4show one embodiment of such a tolerance-compensating fastening arrangement10for fastening the component101to the structure102according to an exemplary embodiment of the invention.FIGS.6to15depict further views of the fastening arrangement10and of its parts during assembly.

Specifically, each male fastener1comprises a fastening bolt3having a serrated outer profile with a plurality of ridges3aarranged one after the other along the fastening bolt3, each ridge3arunning circumferentially around an outer surface of the fastening bolt3(cf.FIGS.8-11in particular). Each ridge3aof the serrated outer profile of the fastening bolt3has an inclined top face3bwith an inclination angle of 60° and a horizontal bottom face3c(cf.FIG.9). The ridges3amay be displaced from each other with a pitch of 1 mm or similar. The fastening bolt3may be affixed to a component-side bracket23of the male fastener1, which is firmly attached to the component101.

In a similar vein, each female fastener2is attached to the structure102via a structure-side bracket22. The structure-side bracket22has a portion that serves as an affixed base plate6of the female fastener2(cf.FIGS.2to4, for example). The base plate6is connected via several spacers21to a cover plate7of the female fastener2. The base plate6and the cover plate7together serve as a structural housing of the female fastener2, in which the further parts are accommodated.

Further, the female fastener2comprises a socket base4arranged on the base plate6within the female fastener2such that the socket base4is slidable along a horizontal tolerance compensation plane H across the base plate6(cf.FIG.7in particular). The socket base4has a conical funnel12, which opens downwards and protrudes through a circular opening in the base plate6, whereby a diameter of the opening is larger than a diameter of the conical funnel12such that the socket base4can still be moved across the base plate6. The expansion/diameter of the opening in the base plate6thus defines a range over which the socket base4is slidable across the base plate6. The conical funnel12is configured to receive the fastening bolt3such that horizontal tolerances between the male fastener1and the female fastener2are compensable to a certain extent by movement of the socket base4within the female fastener2, the movement being actuated through contact of the fastening bolt3with an inner funnel surface13of the conical funnel12.

The working principle of this horizontal tolerance compensation is illustrated inFIGS.6and7. When the male fastener1is offset in the horizontal tolerance compensation plane H with respect to the female fastener2, which means that the fastening bolt3of the male fastener1is not perfectly aligned with the conical funnel12of the female fastener2, the fastening bolt3will contact the inner funnel surface13of the conical funnel12as soon as it enters the funnel12from below during installation of the fastening arrangement10. This can be seen inFIG.6, which shows the bolt3in its reference (target) position within the horizontal plane (e.g. x-y-coordinates). The position of the fastening bolt3may, for example, be set by a jig or respective tooling on the component101. The position of the base plate6, and thus of its opening, is determined on the other hand by the primary structure102position.

With reference toFIG.7, it can be seen that due to the conical shape of the inner funnel surface13any upward movement of the fastening bolt3into the conical funnel12will push the socket base4along the base plate6accordingly until the fastening bolt3is entirely aligned with the opening of the conical funnel12(or until the conical funnel12touches the rim of the circular opening and thus the maximal compensable tolerance range). Hence, tolerances within the horizontal plane H can be compensated within a range that is predefined by the geometric configuration of base plate6and socket base4. In one particular example, deviations of up to ±10 mm may be compensated within the horizontal plane H by the arrangement10. However, the exact range may be scaled according to the respective application and particular need by increasing/decreasing the elements accordingly, in particular the geometry of the conical funnel12and the size of the opening within the base plate6.

The above procedure can be automated because all involved elements are forced into the correct target position by the conical funnel12. On top of that, the installation can be done blindly because the elements find their right installation position by themselves, i.e. the connection is self-finding.

Again referring toFIGS.2to4, the female fastener2further comprises a socket jaw5arranged on the socket base4. One technical purpose of the socket jaw5is to receive the fastening bolt3through the conical funnel12and fix its position along a vertical tolerance compensation axis V, which is oriented perpendicular on the horizontal tolerance compensation plane H, and thereby compensate vertical tolerances between the male fastener1and the female fastener2.

To this end, the socket jaw5comprises three jaw segments11arranged circumferentially around the vertical tolerance compensation axis V such as to form a central jaw opening14configured to receive the fastening bolt3through the conical funnel12of the socket base4. In order to engage the fastening bolt3, each jaw segment11has a serrated inner profile with a plurality of ridges11carranged one after the other along the vertical tolerance compensation axis V and configured complementary to the ridges3aof the fastening bolt3. In order to lock the position of the fastening bolt3along the vertical tolerance compensation axis V, the jaw segments11are configured movable radially with respect to the vertical tolerance compensation axis V to adjust a size of the jaw opening14to retain the fastening bolt3along the vertical tolerance compensation axis V via contact of the serrated inner profile and the serrated outer profile.

The socket jaw5of this embodiment not only serves to compensate vertical tolerances. Another purpose of the socket jaw5is to provide compensation of angular tolerances. To this end, the socket jaw5is configured with a jaw bowl8having a basically spherical concave bearing surface8a. Accordingly, the jaw segments11have a basically spherical convex bearing surface11aon a lower side. Together, the bearing surfaces8a,11aare configured to slidably mount the jaw segments11within the jaw bowl8such that angular tolerances with respect to the vertical tolerance compensation axis V between the male fastener1and the female fastener2are compensable by sliding movement of the fastening bolt3together with the jaw segments11within the jaw bowl8(cf. arrows inFIG.8, the jaw bowl8not being visible in the figure).

FIGS.9to11illustrate how the fastening bolt3is introduced into the jaw opening14between the jaw segments11and then pushed upwards along the vertical tolerance compensation axis V. By lifting the fastening bolt3upwards inFIG.9the respective jaw segments11are pushed upwards and radially outwards through the contact of the inclined top face3bof the ridges3aof the fastening bolt3and the respective faces of the ridges3cof the jaw segment11. Due to the convex bearing surfaces11aon the outside of the jaw segments11, the jaw segments11thus slide along the concave bearing surface8aof the jaw bowl8. As soon as the jaw segment11passes an outer edge of the ridges3aof the fastening bolt3, the direction of movement of the jaw segments11switches from radially outwards to inwards (cf.FIG.10), and the jaw segments11begin to fall down (free from the fastening bolt3) along the bearing surface8aof the jaw bowl8(cf.FIG.11) until they are caught by the subsequent ridge3aof the upwards moving fastening bolt3and are then pushed up and outwards once more. This procedure continues until the fastening bolt3finds its final position along the vertical tolerance compensation axis V.

It should be noted that the jaw segments11are forced back into their radial inward (start) position on their own, that is, by their weight. Hence, a spring element or similar is not necessarily required for the above mechanism to work. Due to the horizontal bottom face3cof the fastening bolt's3ridges3a, the serration of the system is self-closing or self-locking in the sense that once the fastening bolt3is moved into the jaw opening14, the engagement of outer serration and inner serration is closed and the bolt3cannot be moved backwards anymore (at least not on its own). Moreover, due to the rotational symmetry of fastening bolt3and socket jaw5, the fastening arrangement10is insensitive to rotational misalignment between the male fastener1and the female fastener2.

As described above, movement of the fastening bolt in vertical direction V is automatically adjusted dependent on a vertical offset or tolerance between the male fastener1and the female fastener2, wherein the fastening bolt3locks itself in vertical direction V by itself. However, the system also provides a means to lock the arrangement10within the horizontal plane H, as will be described now.

To this end, the socket base4comprises a wedged turning surface15and the socket jaw5comprises a complementary wedged turning surface16for each jaw segment11. More specifically, the socket base4has an annular shape with a rim structure, on which the wedged turning surface15is provided in three azimuthally oriented surface segments, each surface segment corresponding to one jaw segment11. The complementary wedged turning surface16on the other hand is provided at a lower side of the jaw bowl8. More precisely speaking, three bowl protrusions8care provided radially outside on the jaw bowl8, each of which having one complementary wedged turning surface16on a bottom side (cf.FIG.3), via which the socket jaw5slidably rests on the wedged turning surface15of the socket base4. The socket jaw5can now be pushed against the cover plate7by relative rotation of the socket base4and the socket jaw5at the wedged turning surfaces15,16around the vertical tolerance compensation axis V to block movement of the socket base4and the socket jaw5with respect to the base plate6and the cover plate7.

This mechanism to block horizontal movement of the inner parts of the female fastener2is illustrated inFIGS.14and15. InFIG.14, the socket jaw5is spaced apart from the cover plate7and thus the system of socket base4and socket jaw5riding on top of the socket base4can be slid across the base plate6along the horizontal tolerance compensation plane H. InFIG.15the socket base is now turned clockwise (as seen from top of the fastening arrangement10, cf. “lock” direction inFIG.15), which pushes the socket jaw5upwards against the cover plate7(cf. arrows inFIG.15). It should be noted in this respect that the rotational movement of the socket base4is possible even when the fastening bolt3is inserted into the system due to the rotational symmetry of the arrangement, and in particular the fastening bolt3, around the vertical axis V.

In order to complement this force fit between socket jaw5and cover plate7, the cover plate7has a serrated lower surface17and the socket jaw5has a serrated upper surface18complementary formed to the serrated lower surface17of the cover plate7. Hence, both components are not only hold together by friction but also by engagement of the serrated surfaces in a form fit.

As can be seen inFIG.12, the ridges/teeth of the serrated surfaces may be aligned appropriately in order to make sure that the jaw bowl8always keeps the same position (the teeth on the serrated upper surface18of the jaw bowl8have to be aligned with the complementary teeth of the lower serrated surface17of the cover plate7). In the particular example ofFIG.12, the teeth on one of the bowl protrusions8c(top inFIG.12) are oriented perpendicular to the ones on other tow lower bowl protrusions8c(bottom ofFIG.12) within the horizontal plane H. Hence, the respective teeth block sliding movement along one axis within the plane H.

As can be seen inFIG.12, for example, the jaw bowl8further comprises two bowl handles8b, which may be used to engage and hold the jaw bowl8from the outside, e.g. in order to fix it in its position relative to base plate6and cover plate7. It will be clear to the person of skill that the serration of the cover plate7and the jaw bowl5as well as the bowl handles8bcan be omitted in case that the sliding movement can be blocked by friction alone.

As described above, the bearing surfaces8a,11aof the female fastener2have a basically spheroid shape. However, the person of skill will readily acknowledge that other shapes may be suitable in some applications. For example, in other embodiments the concave bearing surface8aof the jaw bowl8and the convex bearing surface11aof the jaw segments11may be configured basically conical, for example.

Still referring toFIG.12, the female fastener2may optionally comprise segment connectors20for coupling the individual jaw segments11with each other in order to provide an improved synchronized movement of the jaw segments11and to avoid uncontrolled movements in vertical direction. The segment connectors20may be configured appropriately to allow the desired movement of the segments11and to block all unwanted degrees of freedom. For example, the jaw segments11may be coupled to each other via a tongue-and-groove connection. In a similar vein, an additional locking element may be implemented to lock the angular tolerance compensation.

Now referring toFIG.13, an additional (central) spring element19may optionally be provided between the cover plate7and the jaw segments11as part of the socket jaw5. The spring element19may be configured to resiliently preload the jaw segments11against the cover plate7in vertical direction, i.e. along the vertical tolerance compensation axis V. Based on this provision, any movement of the jaw segments11in vertical direction can be suppressed, e.g. to avoid vibrations after installation of the system due to a remaining free play in vertical direction.

With reference toFIGS.16to28, an alternative embodiment of the fastening arrangement10is described now, which can also be used to fix the component101to the structure102inFIG.1. In principle, both embodiments can be used in combination to fix components to a structure by utilizing male fasteners and female fasteners of both embodiments in one fastening arrangement.

The fastening arrangement10ofFIGS.16to28also comprises a male fastener1and a corresponding female fastener2. The male fastener1comprises a fastening bolt3with a serrated outer profile having a plurality of ridges3aarranged one after the other along the fastening bolt3and running circumferentially around an outer surface of the fastening bolt3. The female fastener2comprises an affixed base plate6connected to a component-side bracket22and a cover plate7fixed to the base plate6via spacers21. The female fastener2further comprises a socket base4slidably arranged on the base plate6movable along a horizontal tolerance compensation plane H and having a conical funnel12configured to receive the fastening bolt3such that horizontal tolerances between the male fastener1and the female fastener2are compensable by movement of the socket base4within the female fastener2. The horizontal tolerance compensation functions in a similar vein as for the embodiment ofFIGS.2to16(cf.FIGS.6and7in particular).

The female fastener2further comprises a socket jaw5arranged on the socket base4and comprising three identical jaw segments11arranged circumferentially around a vertical tolerance compensation axis V such as to form a central jaw opening14configured to receive the fastening bolt3through the conical funnel12of the socket base4. Also in this case each jaw segment11has a serrated inner profile with a plurality of ridges11carranged one after the other along the vertical tolerance compensation axis V, wherein the ridges3a,11cboth of the fastening bolt3and the jaw segments11are formed as in the embodiment ofFIGS.2to15. In particular, each ridge3aof the serrated outer profile of the fastening bolt3has an inclined top face3bwith an inclination angle of 60° and a horizontal bottom face3c.

However, contrary to the socket jaw5of the embodiment ofFIGS.2to16, the present socket jaw5is not provided with a jaw bowl8and corresponding concave/convex bearing surfaces8a,11a. Instead, the socket jaw5further comprises a retainer ring9around the vertical tolerance compensation axis V. The retainer ring9is configured with a sliding track9aof variable radius for each jaw segment11, in which the respective jag segment11is slidably mounted to facilitate radial movement of the jaw segment11with respect to the vertical tolerance compensation axis V by rotation of the retainer ring9around the vertical tolerance compensation axis V (cf.FIGS.20and21in particular). As in the embodiment ofFIGS.2to15, such radial movement of the jaw segments11is used to adjust a size of the jaw opening14to retain the fastening bolt3along the vertical tolerance compensation axis V via contact of the serrated inner profile and the serrated outer profile and thereby compensate vertical tolerances between the male fastener1and the female fastener2.

This mechanism is illustrated inFIGS.20and21, which depict the retainer ring9and the jaw segments11from the bottom. As can be seen, the jaw segments11are placed on top of the retainer ring9and engage each associated sliding track9aby means of a lock bolt11bfrom below.FIG.20shows the socket jaw5in an open position, in which the jaw segments11are located at an outer radial position within each respective sliding track9asuch that the jaw opening14has a diameter large enough to receive the fastening bolt3therethrough. By turning the retainer ring9clockwise inFIG.21, the jaw segments11are moved radially inwards to an inner radial position. Here, an outer radius Ro of the outer radial position is larger than the inner radius Ri of the inner radial position. For example, there may be a difference of one or several millimeters between inner radius Ri and outer radius Ro, e.g. 1.5 mm. In the present exemplary embodiment, a rotation of 90° is necessary to move the jaw segments11between both radial positions. However, the person of skill will readily acknowledge that various other configurations may be envisaged with a different number of jaw segments11, radial displacements and rotation angles.

Due to this radial movement, the jaw opening14is narrowed down such that the fastening bolt3is engaged at its outer serrated profile by the inner serrated profile of the jaw segments11. As a consequence, the fastening bolt3is fixed under a certain vertical displacement, which thus can be used to compensate tolerances between the male fastener1and the female fastener2along the vertical tolerance compensation axis V.

The retainer ring9may be moved manually for this purpose, e.g. by engaging the retainer ring9at an radially outside surface or a handle provided for this purpose (not shown in the figures). However, alternatively or additionally, an actuator may be provided for automated actuation of the socket jaw5. It will be clear to the person of skill that the retainer ring9may further be configured with a spring element or return spring or the like, which may bias the position of the retainer ring9relative to the jaw segments11, e.g. such that the jaw segments11are located in the radially inward position by default, which means that the retainer ring9has to be actively turned in order to open the jaw opening14for receiving the fastening bolt3. The spring element may also be configured such that the fastening bolt3will push open the jaw opening14, which will then close automatically around the fastening ring3at the final position due to a preload of the spring element.

The retainer ring9also provides a locking function to lock the fastening bolt3in a desired position along the vertical tolerance compensation axis V. To this end, a top face of the retainer ring9is cut-out to form a lock slot9bin each sliding track9aat a radially inward end position, as can be seen inFIGS.20and21. The lock bolt11bof each jaw segment11is configured complementary to the lock slot9bto lock the jaw segments11at the radially inward end position within the retainer ring9. For this purpose, the retainer ring9is configured to lock the jaw segments11by shifting downwards along the vertical tolerance compensation axis V and thereby move the lock slot9baround the lock bolts11b, thus block any further rotational movement of the retainer ring9.

The above mechanism is shown in detail inFIGS.22to25.FIGS.22and23depict the retainer ring9in an unlocked configuration, in which the lock bolt11bhas not entered the lock slot9b. Assuming that the jaw segments11are at the radial inward end position and the fastening bolt3is firmly engaged at the outer serrated profile, the retainer ring9is now shifted by a predefined distance downwards along the vertical axis V, e.g. by 2 mm, so that the lock bolt11benters the lock slot9balong the vertical tolerance compensation axis V and thereby blocks any further rotational movement of the retainer ring9around the vertical tolerance compensation axis V. Thus, retainer ring9and jaw segments11and thus the socket jaw5with the engaged fastening bolt3are locked in position. To unlock the system, the retainer ring9just has to be shifted back in vertical direction.

Again referring toFIGS.16and17, the socket base4comprises a wedged turning surface15and the socket jaw5comprises a complementary wedged turning surface16. Similar to the embodiment ofFIGS.2to15, also in this case the socket jaw5slidably rests with the complementary wedged turning surface16on the wedged turning surface15of the socket base4such that the socket jaw5is pressable against the cover plate7by relative rotation of the socket base4and the socket jaw5at the wedged turning surfaces15,16around the vertical tolerance compensation axis V to block movement of the socket base4and the socket jaw5with respect to the base plate6and the cover plate7. However, in the present embodiment, the wedged turning surfaces15,16are oriented differently from the embodiment ofFIGS.2to15. Moreover, the complementary wedged turning surface16is provided on a bottom side of the jaw segments11(cf.FIG.17), whereas in the embodiment ofFIGS.2to15it is provided on a bottom side of protrusions8con the jaw bowl8.

As can be seen inFIGS.16and17in particular, the wedged turning surface15of the socket base4is divided into three segments, each segment being oriented radially on top of the socket base4with respect to the vertical tolerance compensation axis V and having an inclined slope raising towards the center (cf.FIG.16), e.g. with an angle of 15°. Accordingly, each jaw segment11has one complementary wedged turning surface16that is sloped accordingly in a radially outward direction (cf.FIG.17). Due to this provision, a radially inward movement of the saw segments11automatically implies a vertical upward movement of the same, for example by a few millimeters, e.g. 0.4 mm. The effect of this is illustrated inFIGS.26to28. InFIG.26, the socket jaw5is in an open position, in which the jaw segments11are located at the radially outward position within their respective sliding tracks9a. Thus, the jaw segments11are also located at a lower position along the vertical tolerance compensation axis V, which means that there is a gap between an upper side of the socket jaw5and the cover plate7(above inFIG.26). By turning the retainer9, as shown inFIG.27, the jaw segments11are moved radially inwards and vertically upwards such that the gap is closed and the socket jaw5is pressed against the cover plate7with the jaw segments11. Due to this force fit any movement of the socket base4along the horizontal tolerance compensation plane H is prevented. By shifting the retainer ring9downwards along the vertical tolerance compensation axis V, as seen inFIG.28, the system is put into a locked position, which means that the system is fixed in horizontal as well as vertical direction.

It should be noted that the cover plate7of the present embodiment does not feature a serrated lower surface contrary to the embodiment ofFIGS.2to15, neither is the socket jaw5provided with a complementary serrated upper surface18. It will be clear to the person of skill however that in alternative embodiments such additional means may be provided to further block horizontal movement of the socket base4in a locked/closed state by means of a form fit.

Summarizing, the present invention provides a simple yet effective solution for fastening a component to a structure taking tolerances into account. The solution is self-adjusting vertical and horizontal tolerances (due to the conical funnel12) and may be configured self-closing/locking at least with respect to vertical tolerance compensation (cf. the embodiment ofFIGS.2to15). Horizontal movement may be blocked via a simple turning mechanism, which may be driven by an automatic actuator. Thus, the system can be fully automatized and thus significantly reduce manufacturing time and costs, in particular in aircraft construction. Generally, tolerances in all three dimensions can be compensated up to a predefined amount, e.g. ±10 mm. In addition, angular tolerances may be compensated by several degrees. Existing reference positions of the connected parts are maintained after the connection is closed. A particular advantage of the fastening arrangement10as disclosed is the possibility to manufacture some or all parts of male and female fasteners1,2using a 3D printing or Additive Manufacturing (AM) technique.

In the foregoing detailed description, various features are grouped together in one or more examples or examples with the purpose of streamlining the disclosure. It is to be understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents. Many other examples will be apparent to one skilled in the art upon reviewing the above specification. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

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