Channel fastener with torque-inducing element

Abstract

A channel fastener comprises a rigid washer element and an oblong metal anchoring element. The channel fastener furthermore comprises a connecting element which connects the anchoring element to the washer element, while allowing the anchoring element to rotate around the rotational axis with respect to the washer element. The connecting element comprises a torque-inducing element including at least one limb. The at least one limb is arranged substantially offset from the rotational axis of the anchoring element and adapted for guiding the anchoring element such that when the anchoring element is moved away from the washer in a direction coaxial with the rotational axis, one of the long lateral sides of the anchoring element slides along the limb, whereby a torque is induced on the anchoring element, which rotates the anchoring element around the rotational axis towards the locking position.

Description

[0001] Title: Channel fastener with torque-inducing element

[0002] The invention relates to a channel fastener for fastening an object to an elongate channel element, said channel element having a bottom, an upper side opposite the bottom and lateral walls that interconnect the upper side and the bottom, wherein the upper side includes flanges that extend from the lateral walls towards each other, and a longitudinal slot defined between the flanges and having a slot width.

[0003] Channel fasteners comprising a rigid washer element and an oblong metal anchoring element are known in the art. In use the washer bears with an underside against the outer side of the flanges of the channel element, while the oblong anchoring element, which has a width smaller than the slot width and a length larger than the slot width, is adapted to be inserted in the slot of the channel element and then rotated when inside the channel element such that longitudinal end portions anchoring element engage an inner side of the respective flanges of the channel element in a locking position of the anchoring element. In the locking position of the anchoring element the washer and the anchoring element are clamped on the flanges of the channel element by tightening the anchoring element and the washer towards each other by a bolt or another suitable threaded fastener.

[0004] The anchoring element has to be rotated to the locked position when it is inserted in the channel element through the longitudinal slot. Within the field of channel fasteners there is a type of channel fasteners in which the anchoring element is automatically rotated to a locked position when the anchoring element is inserted through the longitudinal slot of the channel element. The present invention relates to such a channel fastener.

[0005] EP 1 357 304 A1 discloses a channel fastener having an anchoring element, a washer element and a torque-inducing element. The washer element is formed as an L-shaped bracket which is connected to the anchoring element by a bolt. The torque-inducing element is arranged on top of the anchoring element and comprises a central ring and curved spring arms which are attached to the central ring on diametrically opposite locations and are arranged in a point symmetrical way. When the anchoring element is pushed into the longitudinal slot of a corresponding channel element, the curved spring arms slide along the edges of the slot of the channel element and will induce an automatic rotation of the anchoring element. In the locked position of the anchoring element, in which the anchoring element engages the inside of the flanges of the channel element, the spring arms will still engage an outside of the flanges.

[0006] DE 100 36 478 A1 discloses a channel fastener comprising an anchoring element and a torque-inducing element which is arranged on an upper side of the anchoring element. The torque-inducing element includes a plate which is arranged and attached to the upper side of the anchoring element and wings attached to the longitudinal ends of the plate and lying in the same plane as the plate. When the anchoring element is pushed in the slot of the channel element the wings engage the upper side of the flanges of the channel element and elastically deform thereby causing an automatic rotation of the anchoring element towards the locked position. When the anchoring element is in the locked position underneath the flanges of the channel element, the wings engage the outside of the flanges and retain the assembly in a pre-mounting state on the flanges of the channel element. The anchoring element has a threaded bore such that further elements such as a threaded male fastener, a nut and a washer can be mounted to the anchoring element.

[0007] EP 0 837256 B1 discloses a similar channel fastener as DE 10036478. Also in this channel fastener the torque inducing element includes a plate which is arranged and attached to a lower side of the anchoring element and two arcuate elastically deformable lugs attached to the longitudinal ends of the plate. The arcuate lugs are curved out of the plane of the plate. When the anchoring element is pushed in the slot of the channel element, the arcuate lugs engage the edge between the upper side of the flanges and the slot of the channel element and elastically deform, thereby causing an automatic rotation of the anchoring element towards the locked position. The arcuate lugs have bent end portions which engage the upper side of the flanges of the channel element and retain the assembly in a pre-mounting state on the flanges of the channel element when the anchoring element is rotated into the locked position underneath the flanges of the channel element.

[0008] WO 2020 / 171709 discloses a channel fasteners having a torque-inducing element fixed to the anchoring element. The torque-inducing element has resiliently deformable limbs arranged substantially offset from the rotational axis of the anchoring element and slide along the flanges of the channel element upon insertion of the anchoring element in the channel element through the longitudinal slot. The resiliently deformable limbs extend in an uninserted state from the anchoring element towards the washer element, wherein the resiliently deformable limbs have a proximal end located at the anchoring element and a distal end located against the washer element and stay within the contour of the washer element. All of the above-mentioned known channel fasteners have torque inducing elements comprising limbs that are fixed relative to the anchoring element and move and rotate with the anchoring element, wherein the limbs have to interact with the flanges of the channel element to cause the rotation of the torque inducing element and the anchoring element. A disadvantage of this is that the specific embodiment or state of a channel element, e.g. roughness or unevenness of the flange surfaces could negatively influence and hamper the working of the automatic rotation function.

[0009] US 2018 / 0347614 discloses a channel fastener including a channel nut, i.e. an anchoring element, and a retainer. The retainer holds the nut. The retainer has actuation legs which are biased before use and provide a biasing force which rotates the nut in the retainer in use. The retainer furthermore has holding legs that prevent the rotatable nut from rotating before the assembly of channel nut and retainer are placed in channel. When the anchoring element with a part of the retainer is placed in the longitudinal slot of the channel element, the holding legs are deflected by the channel element and release the rotatable nut for rotation and the biased actuation legs force the nut into rotation towards a locking position. A disadvantage of a biased actuation member is that it has the risk that the nut will rotate when the holding legs are accidentally deflected before use, or, during mounting on a channel element, are deflected before the anchoring element is moved entirely beyond the flanges of the channel element.

[0010] The invention has for an object to provide an alternative channel fastener.

[0011] This object is achieved by a channel fastener according to claim 1.

[0012] The channel fastener according to the invention has a connecting element which connects the anchoring element to the washer element, while allowing the anchoring element to rotate around the rotational axis with respect to the washer element. The connecting element comprises a torque-inducing element including at least one limb arranged substantially offset from the rotational axis of the anchoring element and adapted for guiding the anchoring element such that when the anchoring element is moved away from the washer in a direction coaxial with the rotational axis, one of the long lateral sides of the anchoring element slides along the limb, whereby a torque is induced on the anchoring element, which rotates the anchoring element around the rotational axis towards the locking position.

[0013] In the channel fastener according to the invention the anchoring element is moved in the axial direction and moves relative to the limb(s) which causes the rotation. The actuation of the automatic rotation of the anchoring element is only dependent on the force that the user applies on the anchoring element to move the anchoring element away from the washer element. The user applies this force via a shaft which is connected to the anchoring element. For example, a threaded rod can be screwed in the anchoring element which can then be used to push the anchoring element away from the washer element. The limbs do not have to cooperate with other parts than the dedicated anchoring element and thus do not have to interact with the channel element to induce the rotation. This provides a channel fastener with a more robust and reliable automatic rotation function.

[0014] In an embodiment the torque inducing element comprises two limbs which are each arranged at a respective long lateral side of the anchoring element and positioned rotationally symmetric (of order 2) with respect to the rotational axis of the anchoring element.

[0015] In a further embodiment the two limbs are spaced apart over a distance that is slightly larger than the width of the anchoring element.

[0016] In an embodiment the connecting element comprises a base portion that is arranged against the underside of the washer, said base portion having such a dimension perpendicular to the rotational axis of the anchoring element, that the base portion fits in the longitudinal slot between the flanges of the channel element when the bearing face of the washer rests against the outer side of the flanges of the channel element.

[0017] In a further embodiment the two limbs each have a root with which they are connected to the base portion of the connecting element, wherein said roots are spaced apart over a distance which is slightly smaller than the slot width.

[0018] In a further embodiment the base portion defines a receiving space in which the anchoring element is received in the initial position and which inhibits rotation of the anchoring element around the rotational axis from the initial position.

[0019] In a further embodiment the base portion comprises an annular body having an inner contour generally corresponding to an outer contour of the oblong anchoring element, wherein the outer contour is seen in a view colinear with the rotational axis of the anchoring element, and wherein said inner contour defines the receiving space for the anchoring element.

[0020] In a further embodiment the receiving space and the anchoring element generally have a quadrangular shape. In a further embodiment the at least one torque inducing element is connected to the annular body and extends underneath the receiving space and supports the anchoring element.

[0021] In a further embodiment the at least one torque inducing element is arranged near one of the corners of the quadrangular shape.

[0022] In an embodiment the limb(s) is / are formed as a tongue extending inclined in a direction away from the washer and in the width direction of the anchoring element in the initial state. The limbs thus extend inclined downwardly and inwardly underneath the anchoring element in the initial state.

[0023] In an embodiment the torque inducing element is a flexible element adapted to be flexed away when the anchoring element is pushed down on it.

[0024] In an embodiment the connecting element comprises coupling members to couple the connecting element to the washer.

[0025] In an embodiment the connecting element comprises spring members which are connected to the base portion, wherein the respective spring members extend from the base portion to engage the outer side of the respective flanges of the channel element, wherein the spring members are arranged and configured such that when the washer rests with its bearing face against the outer side of the flanges, the spring members are biased.

[0026] In an embodiment the connecting element is made of plastic. As a plastic part the connecting element can efficiently be made in large numbers by injection moulding. It is conceivable though that the connecting element can be made of another suitable resilient material, such as metal, for example spring steel sheet metal.

[0027] In an embodiment the connecting element is made in one piece.

[0028] In an embodiment the fastener furthermore comprises a shaft, which is coupled to the anchoring element and which extends through a through bore in the washer.

[0029] The shaft may be part of a threaded bolt or a threaded rod.

[0030] The anchoring element may be embodied as a nut having a threaded bore. In an embodiment, in the initial position of the anchoring element, the shaft of the threaded bolt or threaded rod is screwed in the threaded bore of the anchoring element to such an extent that the anchoring element can rotate with respect to the shaft, such that when the torque inducing elements cause the anchoring element to rotate around the rotational axis thereof, the shaft does not rotate.

[0031] In an embodiment the shaft has a blocking feature near its end to block unscrewing the shaft entirely out of the anchoring element. The blocking feature may additionally provide a coupling of the anchoring element on the shaft which may facilitate the disassembly of the channel fastener and the channel element.

[0032] The invention will be further elucidated with reference to the drawings, in which:

[0033] Fig. 1 shows, in a view in perspective from above, a channel fastener according to the invention,

[0034] Fig. 2 shows, in a view in perspective from below, the channel fastener of Fig. 1 ,

[0035] Fig. 3 shows a side elevational view of the channel fastener of Fig. 1,

[0036] Fig. 4 shows, in a view in perspective from above, a connecting element of the channel fastener of Fig.1 ,

[0037] Fig. 5 shows, in a view in perspective from below, the connecting element of Fig. 4,

[0038] Fig. 6 shows a side elevational view of the connecting element of Fig. 4,

[0039] Figs 7A - 7D illustrate how the channel fastener of Fig. 1 is mounted on a channel element,

[0040] Fig. 8 shows, in a view in perspective from above, the channel fastener of Fig. 1 assembled with a threaded rod and nut,

[0041] Fig. 9 shows, in a view in perspective from above, the channel fastener of Fig. 1 assembled with a threaded bolt,

[0042] Figs 10 and 11 illustrate how the assembly of Fig. 9 is used to mount a connector the a channel element, and Figs 12A and 12B show a view in perspective view and a front elevational view, respectively, of a channel element on which the channel fastener of Fig. 1 can be mounted.

[0043] Figs 1-3 show a channel fastener 1. The channel fastener 1 comprises a rigid washer element 2, an oblong anchoring element 3 and a connecting element 4. The connecting element is shown separately in Figs 4-6.

[0044] The channel fastener 1 is adapted to be used with an elongate channel element 5 which is shown in Figs 12A and 12B. In the technical field this channel element 5 is often called “a mounting rail” or “a strut rail”. The elongate channel element 5 has a bottom 51, an upper side 52 opposite the bottom 51 and lateral walls 53 that interconnect the upper side 52 and the bottom 51. The upper side 52 includes flanges 54 that extend from the lateral walls 53 towards each other. Typical for strut rails is that the flanges 54 are turned inwards such that their ends 55 face the bottom 51. A longitudinal slot 56 is defined between the flanges 54. The slot 56 has a slot width Ws.

[0045] In a practical embodiment of the channel fastener 1, the washer element 2 and the anchoring element 3 are made of metal, while the connecting element 4 is made of plastic. The connecting element 4 as shown in the figures may be made in one piece from plastic material by injection moulding.

[0046] Instead of metal, the washer element 2 may also be made of another suitable material, e.g. certain high strength plastic materials.

[0047] The washer element 2 has an underside including a bearing face 21 that is arranged for resting against the outer side of the flanges 54 of the channel element 5. Furthermore, the washer element 2 has a central bore 22 through which a shaft of a male fastener, such a bolt or a threaded rod can pass.

[0048] The anchoring element 3 is located on the side of the washer element 2 where the bearing face 21 is located. The anchoring element 3 has two opposite long lateral sides 33, two opposite short lateral sides 34, a top side 31 (cf. Fig. 7C) facing the washer element 2 and a bottom side 32 opposite the top side 31. The anchoring element 3 has longitudinal end portions 35 adapted to engage an inner side, in the shown embodiment of the channel element in particular the in-turned ends 55, of the respective flanges 54 of the channel element 5 in a locking position of the anchoring element (cf. Fig. 7D). The anchoring element 3 has a threaded bore 36. In essence the anchoring element 3 is thus embodied as a nut. The bore 36 defines a rotational axis 37 (cf. Fig. 2) around which the anchoring element 3 is rotatable from an initial position (Fig. 7A) to the locking position (cf. Fig. 7D) as is illustrated in Figs 7A-7D.

[0049] The oblong anchoring element 3 has a width smaller than the slot width Wsand a length larger than the slot width Ws.

[0050] The connecting element 4 connects the anchoring element 3 to the washer element 2. The connecting element 4, which is shown separately in Figs 4-6, comprises a base portion 41 that is arranged against the underside of the washer element 2.

[0051] The base portion 41 comprises an annular body 42 having an inner contour generally corresponding to an outer contour of the oblong anchoring element 3. In the embodiment shown in the figures, the annular body 42 has a quadrangular shape, in particular generally a rectangular shape having a longitudinal dimension and a smaller width dimension. The outer contour of the anchoring element 3 is seen in a view colinear with the rotational axis 37 of the anchoring element 3. The inner contour of the annular body defines a receiving space 43 for the anchoring element 3. The receiving space 43 receives the anchoring element 3 in the initial position as is best visible in Fig. 2, and inhibits rotation of the anchoring element 3 around the rotational axis 37 from the initial position. The annular body 42 has such a width dimension that the base portion 41 fits in the longitudinal slot 56 between the flanges 54 of the channel element 5 when the anchoring element is inserted in the slot 56, which is illustrated in Figs 7A - 7D.

[0052] The connecting element 4 has coupling members 44 comprising hooking members 45 and positioning lugs 46, which are formed on the base portion 41. The hooking members 45 hook over the edge of upper side of the washer element 2 and the positioning lugs 46 are received in corresponding positioning recesses in the edge of the washer element 2. The washer element 2 rests on an upper surface of the annular body 42 and is coupled thereto by the coupling members 44, as is best visible in Fig. 1 .

[0053] A pair of tongues 47 is connected to the annular body 42 by a respective root 49. Each tongue 47 is arranged near one of two opposite corners of the quadrangular shape and extends in the width direction of the annular body 42 inclined away from the washer element 2 underneath the receiving space 43. This arrangement of the tongues 47 supports the anchoring element 3 when it is in the receiving space, as is best visible in Fig. 3. The roots 49 are spaced apart over a distance which is slightly smaller than the slot width Ws. The tongues 47 have a length such that they do not exceed the width dimension of the annular body 42, whereby the tongues 47 can pass the slot 56 without touching the flanges 54 of the channel element 5, as is illustrated in Figs 7A - 7D.

[0054] The tongues 47 are torque inducing elements. The tongues 47 are arranged substantially offset from the rotational axis 37 of the anchoring element 3. In particular the tongues 47 are positioned rotationally symmetric, of order 2, with respect to the rotational axis 37 of the anchoring element 3. The tongues 47 are adapted for guiding the anchoring element 3 such that when the anchoring element moves away from the washer 2 in a direction coaxial with the rotational axis 37, each one of the long lateral sides 33, and in this case particularly a lower edge 33A of the respective long lateral side 33 of the anchoring element 3, slides along respective one of the tongues 47. The lower edge 33A is advantageously a rounded edge such that there is a good sliding contact between the edge 33A and the respective tongue 47. The sliding of the edge 33A along the tongue 47 cause a reaction force on the anchoring element 3. The reaction force at the mentioned offset arrangement of the tongues 47 causes a rotation of the anchoring element around the rotational axis 37.

[0055] The tongues 47 are flexible and adapted to be flexed away when the anchoring element 3 is pushed down on it as is shown in Figs 7B and 7C.

[0056] It is noted that the tongues 47 are an example of possible torque inducing elements. Also limbs with another shape, such as for example rod shaped may be formed. Flexibility of the limbs may be advantageous, but is with some shapes of the limbs not strictly necessary since also by simply a sliding guidance of the anchoring element, the rotation of the anchoring element towards the final position can be achieved. The latter depends on the angle of inclination of the tongues or other shaped limbs. The angle of inclination is illustrated in Fig. 6 and indicated by a. If the angle of inclination a is small, or even zero, flexibility of the tongues or other limbs may be necessary. If the angle of inclination a is larger, said flexibility may not be necessary.

[0057] The connecting element 4 furthermore comprises spring members 48 which are connected to the base portion 41. In the specific embodiment shown in the figures, the spring members 48 are formed as semi-annular members, in the specific embodiment more or less U-shaped members, wherein the legs 48A of the U-shaped member are connected to base portion 41 at the location of the coupling members 44. The connecting leg 48B of the U-shape is in the axial direction, i.e. a direction colinear with the rotational axis 37, spaced apart from the washer bearing face 21. The legs 48, thus extend down with an angle of inclination illustrated in Fig. 6 with p. The respective spring members 48 extend from the base portion 41 to engage the outer side of the respective flanges 51 of the channel element 5, which is illustrated in Fig. 7 A, or to engage for example a surface next to an elongate mounting opening in a coupling element, which is illustrated in Fig. 11. The spring members 48 are arranged and configured such that when the washer element 2 is moved with its bearing face 21 towards the outer side of the flanges 54 or the surface of the connecting element, the spring members 48 are biased.

[0058] In use the channel fastener 1 will also comprise a shaft that is connected with the anchoring element. The shaft may be part of a male fastening element such as a threaded rod 6 or a bolt 8 which is screwed in the threaded bore 36 of the anchoring element as is shown in Figs 8 and 9, respectively. The threaded rod can be combined with a nut 7 as is shown in Fig. 8. A threaded rod or a bolt can be retrofitted to a common channel fastener 1 by the user. It is however also conceivable that the anchoring element and the shaft are pre-connected or are integral parts or are unreleasably connected to each other, e.g. by welding.

[0059] In Figs 7A - 7D is illustrated how the assembly of Fig. 8 is mounted to a channel element 5 that is shown in Figs 12A and 12B.

[0060] The user positions the channel fastener 1 with the anchoring element 3 with the longitudinal dimension aligned with the slot 56. The roots 49 of the tongues 47 and the annular body 42 just fit in the slot 56 between the flanges 54 as is shown in Fig 7A. The spring elements 48 rest on the upper side of the flanges 54 but are not biased yet in the state shown in Fig. 7A. The washer element 2, and in particular the bearing surface 21, is spaced apart from the upper side 52 of the channel element 5. The anchoring element 3 is held within the receiving space 43 defined by the annular body 42, because the anchoring element 3 rests with the edges 33A on the inclined tongues 47. The annular body 42 encloses the outer contour of the anchoring element 3 and prevents rotation of the anchoring element 3.

[0061] Next, the user can push the threaded rod 6 towards the bottom 51 of the channel element 5 and thereby push the anchoring element 3 out of the receiving space 43. The force on the threaded rod 6 and the anchoring element 3 deflects the tongues 47, as is shown in Fig. 7B. Furthermore the edges 33A of the anchoring element 3 slide along the tongues 47 whereby the anchoring element 3 starts to rotate, which is also visible in Fig. 7B.

[0062] By pushing the threaded rod 6 further down, as is shown in Fig. 7C, the anchoring element 3 rotates further while sliding with the respective edges 33A along the respective tongues 47. At some point the respective edges 33A of the anchoring element are moved beyond the end of the tongues 47. At that moment the tongues 47, which had been biased by the deflection, will resiliently snap back to their original shape, whereby the long lateral sides 33 of the anchoring element 3 are more or less parallel with the tongues 47. The anchoring element 3 is now locked between the two tongues 47 which prevents rotation of the anchoring element 3 around the rotational axis 37 in either direction (clockwise or counter clockwise). This state is shown in Fig. 7D. It is noted that the Figs 7B and 7C show intermediate states of the fastener during movement for illustrating the working of the rotating mechanism. In practice however, this rotating movement of the anchoring element 3 is a rather quick snap-like motion which is difficult to observe by the user in real time.

[0063] In the meantime the spring elements 48 are biased by the force exerted on the channel fastener 1 towards the bottom 51 of the channel element 5. When the user releases the threaded rod 6, the biased spring elements 48 pull the top side 31 of the anchoring element 3, which is in the locking position, in engagement with the end 55 of the flanges 54 of the channel element 5, as is visible in Fig. 7D. The channel fastener is now in a preliminary mounting state on the channel element 5. If the user pushes down the fastener 1 the top side 31 of the anchoring element 3 and the ends 55 of the flanges 54 can be temporarily spaced apart such that the channel fastener 1 can be slid along the channel element 5 in the longitudinal direction to a desired position. After the channel fastener 1 is brought in the desired position, the user can tighten the nut 7 and thereby move the washer element 2 and the anchoring element 3 towards each other and clamp the flanges 54 of the channel element 5 between them. In this way the channel fastener 1 is secured to the channel element 5.

[0064] In another embodiment the channel fastener 1 can be combined with a threaded bolt 8. This assembly, which is shown in Fig. 9 can be used to mount for example a channel connector 10 on a channel element 5, which is illustrated by Figs 10 and 11. Essentially this assembly is mounted in the same way as the assembly of Fig 8 that is mounted as illustrated in Figs 7A - 7D, only now the user pushes the bolt instead of the threaded rod and finally tightens the bolt to secure the channel fastener 1 with respect to the channel element.

[0065] The shaft preferably has a blocking feature near its end to block unscrewing the shaft entirely out of the bore 36 of the anchoring element 3. The blocking feature may comprise notches made in the male thread on the shaft near the end of the shaft. The notches form a damage in the male thread that is made on purpose and prevents a further cooperation with the female thread in the threaded bore of the anchoring element 3. The notches thereby block a further rotation of the anchoring element 3. Thus the anchoring element 3 cannot be lost from the shaft.

[0066] In the initial position of the anchoring element 3, the shaft of the threaded bolt 8 or threaded rod 6 is screwed in the threaded bore 36 of the anchoring element 3 to such an extent that the anchoring element 3 can rotate with respect to the shaft, such that when the torque inducing elements 47 cause the anchoring element 3 to rotate around the rotational axis 37 thereof, the shaft does not rotate. In other words, in the initial state of the anchoring element 3, the anchoring element 3 is, in the axial direction of the shaft, spaced apart from the notches such that the anchoring element 3 can rotate with respect to the shaft when it is to be rotated by the torque inducing elements 47 from the initial position to the locking position.

[0067] The notches not only block screwing the shaft out of the bore 36 of the anchoring element, but also provide a friction sufficient to rotatably couple the anchoring element 3 and the shaft. This facilitates to disassemble the channel fastener 1 from the channel element 5. The shaft is rotated with respect to the stationary anchoring element 3 located in the channel element 5 in the locking position, until the notches reach the female thread in the bore 36 and a coupling between the anchoring element 3 and the shaft is established. In this coupled state the anchoring element 3 can be rotated with the shaft of the threaded rod 6 or bolt 8 and can be guided via the tongues 47 from the locking position to the initial position in which the channel fastener 1 can be retracted.

Claims

CLAIMS1. Channel fastener for fastening an object to an elongate channel element, said channel element having a bottom, an upper side opposite the bottom and lateral walls that interconnect the upper side and the bottom, wherein the upper side includes flanges that extend from the lateral walls towards each other, and a longitudinal slot defined between the flanges and having a slot width, wherein the fastener comprises: a rigid washer element, which has an underside including a bearing face that is arranged for resting against the outer side of the flanges of the channel element; an oblong metal anchoring element having a width smaller than the slot width and a length larger than the slot width, said anchoring element being located on the side of the washer element where the bearing face is located, wherein the anchoring element has two opposite long lateral sides, two opposite short lateral sides, a top side facing the washer element and a bottom side opposite the top side, wherein the anchoring element has longitudinal end portions adapted to engage an inner side of the respective flanges of the channel element in a locking position of the anchoring element and has a rotational axis around which the anchoring element is rotatable from an initial position to the locking position;- a connecting element which connects the anchoring element to the washer element, while allowing the anchoring element to rotate around the rotational axis with respect to the washer element, said connecting element comprising a torque-inducing element including at least one limb arranged substantially offset from the rotational axis of the anchoring element and adapted for guiding the anchoring element such that when the anchoring element is moved away from the washer in a direction coaxial with the rotational axis, one of the long lateral sides of the anchoring element slides along the limb, whereby a torque is induced on the anchoring element, which rotates the anchoring element around the rotational axis towards the locking position.

2. Channel fastener according to claim 1, wherein the torque inducing element comprises two limbs which are each arranged at a respective long lateral side of the anchoring element and positioned rotationally symmetric (of order 2) with respect to the rotational axis of the anchoring element.

3. Channel fastener according to claim 2, wherein the two limbs are spaced apart over a distance that is slightly larger than the width of the anchoring element.

4. Channel fastener according to any one of the preceding claims, wherein the connecting element comprises a base portion that is arranged against the underside of the washer element, said base portion having such a dimension perpendicular to the rotational axis of the anchoring element, that the base portion fits in the longitudinal slot between the flanges of the channel element when the bearing face of the washer rests against the outer side of the flanges of the channel element.

5. Channel fastener according to claim 4, wherein the two limbs each have a root with which they are connected to the base portion of the connecting element, wherein said roots are spaced apart over a distance which is slightly smaller than the slot width.

6. Channel fastener according to claim 4 or 5, wherein the base portion defines a receiving space in which the anchoring element is received in the initial position and which inhibits rotation of the anchoring element around the rotational axis from the initial position.

7. Channel fastener according to claim 6, wherein the base portion comprises an annular body having an inner contour generally corresponding to an outer contour of the oblong anchoring element, wherein the outer contour is seen in a view colinear with the rotational axis of the anchoring element, and wherein said inner contour defines the receiving space for the anchoring element.

8. Channel fastener according to claim 6 or 7, wherein the receiving space and the anchoring element generally have a quadrangular shape.

9. Channel fastener according to any one of the claim 6-8, wherein the at least one torque inducing element is connected to the annular body and extends underneath the receiving space and supports the anchoring element.

10. Channel fastener according to claims 8 and 9, wherein the at least one torque inducing element is arranged near one of the corners of the quadrangular shape.

11. Channel fastener according to any one of the preceding claims, wherein the limb(s) is / are formed as a tongue extending inclined in a direction away from the washer and in the width direction of the anchoring element in the initial state.

12. Channel fastener according to any one of the preceding claims, wherein the torque inducing element is a flexible element adapted to be flexed away when the anchoring element is pushed down on it.

13. Channel fastener according to any one of the preceding claims, wherein the connecting element comprises coupling members to couple the connecting element to the washer.

14. Channel fastener according to any one of the preceding claims, wherein connecting element comprises spring members which are connected to the base portion, wherein the respective spring members extend from the base portion to engage the outer side of the respective flanges of the channel element, wherein the spring members are arranged and configured such that when the washer rests with its bearing face against the outer side of the flanges, the spring members are biased.

15. Channel fastener according to any one of the preceding claims, wherein the connecting element is made of plastic.

16. Channel fastener according to any one of the claims 1-14, wherein the connecting element is made of metal, e.g. spring steel.

17. Channel fastener according to any one of the preceding claims, wherein the connecting element is made in one piece.

18. Channel fastener according to any one of the preceding claims, wherein the fastener furthermore comprises a shaft, which is coupled to the anchoring element and which extends through a through bore in the washer.

19. Channel fastener according to claim 18, wherein the shaft is part of a threaded bolt or a threaded rod.

20. Channel fastener according to any one of the preceding claims, wherein the anchoring element is embodied as a nut having a threaded bore.

21. Channel fastener according to claims 19 and 20, wherein, in the initial position of the anchoring element, the shaft of the threaded bolt or threaded rod is screwed in the threaded bore of the anchoring element to such an extent that the anchoring element can rotate withrespect to the shaft, such that when the torque inducing elements cause the anchoring element to rotate around the rotational axis thereof, the shaft does not rotate.

22. Channel fastener according to any one of the claims 19-21, wherein the shaft has a blocking feature near its end to block unscrewing the shaft entirely out of the anchoring element.

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