WO2010086016A1

WO2010086016A1 - A device for locking a helical element

Info

Publication number: WO2010086016A1
Application number: PCT/EP2009/050916
Authority: WO
Inventors: Lars Barkman; Joachim Ljungkvist
Original assignee: Abb Technology Ab
Priority date: 2009-01-28
Filing date: 2009-01-28
Publication date: 2010-08-05

Abstract

A device (102; 202) for locking a helical element (302) to a unit (502, 504), the helical element (302) having several turns (304) and being adapted to house a length of at least one cable (508). The device (102; 202) comprises a rigid hollow sleeve (104; 204) defining a longitudinal axis (x-x) and being insertable into the helical element (302), and the sleeve (104; 204) is adapted to surround a longitudinal extension of the at least one cable (508). The device (102; 202) comprises at least two members (106, 108; 206, 208) each comprising a radial extension (110, 112; 210, 212) outside the sleeve (104; 204). Each radial extension (110, 112; 210, 212) extends substantially radially in relation to the longitudinal axis of the sleeve (104; 204) and is adapted to engage between two turns (304) of the helical element (302). The members (106, 108; 206, 208) are spaced apart in the circumferential direction, and in that the members (106, 108; 206, 208) are adapted to be locked into engagement with said unit (502, 504). An arrangement for protecting at least one cable comprising said helical element (302) and said device (102; 202).

Description

A DEVICE FOR LOCKING A HELICAL ELEMENT

Technical Field The present invention relates to a device for locking a helical element to a unit, the helical element having several turns along its longitudinal extension and being adapted to house and surround a length of at least one cable. The device comprises a rigid hollow sleeve defining a longitudinal axis and being insertable into the inside of the helical element, and the sleeve is adapted to surround a lon- gitudinal extension of the at least one cable. The present invention also relates to an arrangement for protecting at least one cable extending between two units which are movable in relation to each other, which arrangement comprises a helical element and a device of the above-mentioned kind, and to an apparatus comprising two units which are movable in relation to each other, between which units at least one cable extends, and an arrangement for protecting said at least one cable.

Background of the Invention

When connecting one cable, or several parallel cables, for example electric cables, between two units which are continuously moving in relation to each other, the cables are flexed and turned and subjected to wear when the cables come into contact with other surfaces, such as surfaces of the two units or other parts of the apparatus to which the units are mounted. The wear is especially prominent at the attachments connecting or attaching the cables to each unit.

Two units moving in relation to each other and where cables extend there between can be found in the following applications: In Robots, where one unit is stationary and the other units is moving, such as a moving robot arm connected to the stationary unit via a joint, or where both units are in the form of arms movingly arranged. In different types of vehicles, for example trains, where the two units are in the form of two coaches, trucks, where the truck is connected to its trailer, dig- ging machines having arms and a shovel moving in relation to each other. There are numerous other applications where cables must extend between two units moving in relation to each other. One way of protecting the cables is to place the electric cables inside a helical element, i.e. a helically shaped element, which surrounds the cables and extends between the two units. The helical element protects the cables from coming into contact with other surfaces and thus protects the cable from wear. A heli- cal element is suitable for cable protection, since it is flexible and movable in all planes, which allows the helical element and the cables to move in a suitable way, and at the same time, the helical element is rigid enough to protect the cables.

However, when the two ends of the helical element are free and not attached to the two units, there is a wear on the cables, on the helical element and on each unit because of the continuous movement of the ends of the helical element in relation to the cables and the units. To overcome this wear, the ends of the helical element can simply be attached to the two units, which has been done in the prior art by attaching the turn closest the unit by way of attachments in the form of simple clips or straps. However, these kinds of attachments are weak and sensitive to wear. Further, because of the flexibility and movement of the helical element in all planes in relation to the cables, there is still a prominent wear on the cables inside the helical element in those locations where to the cables are connected to the unit via attachments, especially since the helical element can bend in principle all directions transverse to the longitudinal extension of the cables. In the prior art, several other solutions for attaching a helical element to a unit are suggested.

DE 10 2006 039 659-A1 describes the locking of the ends of a spring between to units moving in relation to each other, for example between a door and the door frame, inside which spring an electric cable extends. The spring is locked to each unit by means of an attachment element provided with inner threads which engage and lock the spring. The position of the cable inside the spring is secured by a cord grip which rests against the end of the spring. The cord grip is in the form of a hollow tube through which the cable extends. The cord grip provides strain release for the cable in the attachment region. US 6,297,453-B1 describes the attachment of the ends of a helical spring inside which an electric cable extends. The attachment is effected by an outer sleeve, having internal threads with the same thread profile as the spring, which is screwed onto the spring, and an inner locking sleeve which is pressed inside the spring opposite the outer sleeve. The outer sleeve is then attached to a unit. US 6,734,367-B2 describes a cable protecting coil spring having brim portions, or neck portions, and these portions engage complementary spaces in attachment means provided on members of an industrial robot, whereby the spring is fixed to each member. JP 2001028826-A describes a U-shaped spiral wire forming an external recess in which a cable extends, and the cable is retained in the external recess by a press plate having legs engaging between the turns of the spiral wire. Each end of the spiral wire is provided with a loop for attaching the spiral wire.

DD 293 921 -A5 describes a spiral structure in order to distribute the tensile forces acting on a wire or rope when suspended.

However, there is a need for an efficient locking of a helical element to a unit, which provides an uncomplicated procedure to lock and, if necessary, unlock the helical element, which is durable and secure, and which efficiently protects any cable or cables, extending within the helical element and between two units mov- able in relation to each other, from wear.

The Object of the Invention

The object of the present invention is thus to provide an improved locking of a helical element to a unit, which is secure and durable.

Summary of the Invention The above-mentioned object of the present invention is attained by a device as defined in the appended independent claim 1.

Accordingly is defined a device for locking a helical element to a unit, the helical element having several turns along its longitudinal extension and being adapted to house and surround a length of at least one cable, which device comprises a rigid hollow sleeve defining a longitudinal axis (x-x) and being insertable into the inside of the helical element, and the sleeve is adapted to surround a longitudinal extension of the at least one cable, characterized in that the device comprises at least two members each comprising a radial extension on the outside of the sleeve, in that each radial extension extends substantially radially in relation to the longitudinal axis of the sleeve and is adapted to engage between two turns of the helical element, in that the members are spaced apart in the circumferential direction, and in that the members are adapted to be locked into engagement with said unit. Hereby, an efficient locking of a helical element to a unit is provided. The innovative structure of the device according to the present invention provides a durable and secure locking. The sleeve and members are made of a durable and suitable material and given suitable proportions to provide the proper rigidity. The device of the present invention provides an uncomplicated procedure to lock and, if necessary, unlock the helical element.

The locking of the helical element is for example effected by pushing one of the end portions of the helical element over the sleeve while rotating the helical element in relation to the device, whereupon the members subsequently engage between turns of the helical element. Alternatively, the device can be rotated in relation to the helical element while the sleeve engages the inside of the helical element. Subsequently, the members are locked into engagement with said unit.

The rigid sleeve surrounding the cable at the entry/exit of the helical element, efficiently protects the cables, extending within the helical element and be- tween two units movable in relation to each other, from wear, because the sleeve prevents the helical element from bending in direction transverse to the longitudinal extension of the cable. The device is uncomplicated in its structure and uncomplicated to manufacture, and therefore provides an inexpensive locking of the helical element. The members can be adapted to be locked into engagement di- rectly with the unit, or via any intermediate element or elements.

One or several cables can extend and be protected within the helical element. Electric cables are advantageously protected by the device according to the present invention by extending inside the helical element. However, a cable to be protected is not limited to an electric cable but can be any other kind of cable, such as an air pipe for a pneumatic device, a hydraulic pipe for a hydraulic device, a cooling water hose for cooling devices etc.

According to an advantageous embodiment of the device according to the present invention, the sleeve has an axial extension adapted to cover at least two turns of the helical element. Hereby, the sleeve efficiently protects the cables at the entry/exit of the helical element from coming into contact with the helical element and the resulting wear, and the axial extension of the sleeve provides an outer surface of a suitable length, against which the helical element rests to attain a secure engagement between the device and the helical element, whereby a secure and durable locking of the helical element is achieved. Advantageously, the sleeve has an axial extension adapted to cover at least three turns of the helical element.

The outer cross-section of the sleeve can have any shape which is adapted to be fitted inside the helical element. Advantageously, the outer cross- section of the sleeve is designed such that the sleeve abuts the inside of the helical element at several positions around the circumference. According to an advantageous embodiment of the device according to the present invention, the outer cross-section of the sleeve is substantially circular. Since inexpensive and suitable helical elements are circular-cylindrical, a substantially circular outer cross-section of the sleeve provides an efficient engagement with the inside of a circular helical element, and a secure locking of the helical element is attained.

According to an advantageous embodiment of the device according to the present invention, where the outer cross-section of the sleeve is substantially circular, the outer diameter of the sleeve is slightly larger than the inner diameter of the helical element, whereby the sleeve is adapted be snug-fitted inside the helical element and a further improved locking of the helical element is attained.

According to another advantageous embodiment of the device according to the present invention, the inner cross-section of the sleeve is substantially circular. Hereby, a large space within the sleeve is provided for the cables to pass through, and the inner surface of the sleeve is smooth and does not present any corners, and thus minimizes any wear on the cables which may be caused by the contact between the inside of the sleeve and the cables. Consequently, the protection of the cables from wear is further improved.

According to yet another advantageous embodiment of the device accord- ing to the present invention, the length of the radial extension of each member exceeds the distance between the inner diameter and the outer diameter of the helical element. Hereby, the engagement between the members and the turns of the helical elements is further improved, providing a further improved locking of the helical element. According to still another advantageous embodiment of the device according to the present invention, the two members are situated substantially diametrically opposite to each other in relation to the sleeve. By this location of the two members, an efficient engagement between the members and the turns of the helical elements is provided, and a secure and durable locking of the helical ele- merits is achieved. By providing the members diametrically opposite to each other and through their locking engagement with the unit, the sleeve can be allowed to move to a certain degree in a plane perpendicular to the longitudinal axis of the sleeve without causing any substantial wear on the cables. This embodiment is advantageous in applications where a limited rotation of the sleeve about an axis perpendicular to the longitudinal axis of the sleeve in relation to the unit is desired, while the cables remains protected from wear.

According to an advantageous embodiment of the device according to the present invention, where the two members are situated substantially diametrically opposite to each other in relation to the sleeve, each member defines a longitudinal axis, and the longitudinal axes of the two members are essentially in alignment with one and the same diameter of the sleeve. By this embodiment, the above- mentioned limited rotation of the sleeve about an axis substantially perpendicular to the longitudinal axis of the sleeve is effected in an efficient way. According to a further advantageous embodiment of the device according to the present invention, each of the two members defines a longitudinal axis and is adapted to be rotatable about its longitudinal axis in relation to said unit when locked into engagement therewith. By this embodiment, the above-mentioned limited rotation of the sleeve about an axis perpendicular to the longitudinal axis of the sleeve is effected in an efficient way.

According to another advantageous embodiment of the device according to the present invention, the members are anchored to the sleeve. Each member can be anchored to the sleeve by welding, threads etc., or the member can be integrally formed with the sleeve. Hereby, the procedure to lock and, if necessary, unlock the helical element is further improved and made even less complicated. Additionally, the locking of the helical element to the device is further improved and made more secure, which further improves the locking of a helical element to a unit. Alternatively, the sleeve is provided with recesses each adapted to receive and retain a corresponding member. According to an advantageous embodiment of the device according to the present invention, where the members are anchored to the sleeve, each of the two members is split into two pieces in a plane substantially parallel to its longitudinal axis, and the sleeve is axially cut into two pieces such that each piece of the sleeve is provided with one piece of each member. By this embodiment, the de- vice can be applied around cables without being slipped on around the cables from one of the ends of the cables. This is suitable if the device needs to be exchanged due to wear on site. By splitting each member into two pieces and when the member pieces of each member are received in a recess provided in the unit to provide for the member's locking engagement with said unit, the axial sliding of the two separate pieces of the sleeve is prevented. By this, the procedure to lock and, if necessary, unlock the helical element is further improved and further simplified.

According to still another advantageous embodiment of the device accord- ing to the present invention, the device comprises an attachment arrangement adapted for attaching the device to the unit. The attachment arrangement comprises an attachment element adapted to be anchored to said unit, the attachment element being provided with means for locking the members into engagement with the unit. Said means can be in form of a recess adapted to receive a member, and the recess can advantageously be complementary to the received member.

According to yet another advantageous embodiment of the device according to the present invention, said attachment element is adapted to axially lock the device in relation to the attachment element. Hereby, an efficient axial locking of the helical element to the unit is attained when the attachment element is anchored to the unit, whereby an efficient and secure locking of the helical element to the unit is provided.

According to yet an embodiment, the attachment arrangement comprises an intermediate sleeve applicable around the rigid hollow sleeve and the helical element, and provided with holes adapted to receive and be engaged by the two members, and the intermediate sleeve being rotatably mounted in the attachment element, around the aligned longitudinal axes of the two members.

Further, the above-mentioned object of the present invention is attained by an arrangement for protecting at least one cable extending between two units which are movable in relation to each other, which arrangement comprises a helical element having several turns along its longitudinal extension and being adapted to house and surround a length of at least one cable, and a device for locking the helical element to one of the units, where the device comprises the features mentioned in any of the claims 1 to 13. By this arrangement, an efficient protection of any cables extending within a helical element is provided as described above in connection with the embodiments of the device according to the present invention.

The above-mentioned object of the present invention is also attained by an apparatus comprising two units which are movable in relation to each other, between which units at least one cable extends, and an arrangement for protecting said at least one cable, where the arrangement comprises the features mentioned in claim 14.

The helical element having several turns can take different forms and be designed in different ways. The helical element can be in the form of a helically shaped spring formed from a wire made of metal, plastic or any other material.

The helical element can be in the form of a helical coil formed from a flat strip or tape made of metal, plastic or any other material.

Further advantageous embodiments of the device, the arrangement and the apparatus according to the present invention and further advantages with the present invention emerge from the detailed description of embodiments.

Brief Description of the Drawings

The present invention will now be described, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, in which:

Fig. 1 a is schematic perspective view of a first embodiment of the device according to the present invention;

Fig. 1 b is a schematic front view of the device of Fig. 1 a;

Fig. 1 c is a schematic side view of the device of Fig. 1 a; FFiigg.. 11dd is a schematic top view of the device of Fig. 1a;

Fig. 2a is schematic perspective view of a second embodiment of the device according to the present invention;

Fig. 2b is a schematic front view of the device of Fig. 2a;

Fig. 2c is a schematic side view of the device of Fig. 2a; FFiigg.. 22dd is a schematic top view of the device of Fig. 2a;

Figs. 3a-3d are various schematic views of the first embodiment of the device comprising a first embodiment of an attachment device according to the present invention; Figs. 4a-4b are perspective schematic views of the first embodiment of the device comprising a second embodiment of an attachment device according to the present invention; and

Fig. 5 is a partial schematic perspective view illustrating an embodi- ment of the apparatus comprising two units which are movable in relation to each other, and comprising the arrangement according to the present invention.

Detailed Description of Preferred Embodiments

Figs. 1 a-1 d show a first embodiment of the device 102 for locking a helical element to a unit according to the present invention. The unit can for example be a part of an industrial robot, a train, a truck, or any other kind of vehicle or apparatus. The device 102 comprises a circular-cylindrical sleeve 104 which is rigid, hollow and made of a suitable metal material. The sleeve 104 has a first end 105 where the sleeve 104 forms a first opening and a second end 107 where the sleeve 104 forms a second opening. The sleeve 104 defines a longitudinal axis x-x and is insertable into the inside of the helical element, and the sleeve 104 is adapted to surround a longitudinal extension of at least one cable which extends within the helical element. The device 102 comprises two members 106, 108 each comprising a radial extension 1 10, 1 12 outside the sleeve 104, and each radial extension 110, 112 extends substantially radially in relation to the longitudinal axis x-x of the sleeve 104. The two members 106, 108 are anchored to the sleeve 104 and spaced apart in the circumferential direction of the sleeve 104, and the members 106, 108 are adapted to be locked into engagement with the unit, directly or via any intermediate element, to which the helical element is being locked. The outer cross-section of the sleeve 104 is substantially circular, and the inner cross- section of the sleeve 104 is also substantially circular. However, other shapes of the cross-sections can be applied. The circular inner cross-section provides a smooth inner surface and a maximal space for the cables extending therethrough. Each member 106, 108 defines a longitudinal axis, and the longitudinal axes of the two members 106, 108 are essentially in alignment with one and the same diameter of the sleeve 104, and consequently, the two members 106, 108 are situated diametrically opposite to each other in relation to the sleeve 104. Fig. 1 a and 1d show that the two members 106, 108 are circular-cylindrical. Fig 1 c shows that the two members 106, 108 are displaced towards the first end 105 of the sleeve

104 and thus positioned closer to first end 105 of the sleeve 104 and farther away from the second end 107 of the sleeve 104, whereby the outer surface of the sleeve 104 is larger in the axial direction between the second end 107 and the members 106, 108 than then outer surface of the sleeve 104 between the first end

105 and the two members 106, 108.

Figs. 2a-2d show a second embodiment of the device 202 for locking a helical element to a unit according to the present invention, which in several ways corresponds to the first embodiment. However, in the second embodiment, each of the two members 206, 208 is split into two pieces 206a, 206b, 208a, 208b in a plane substantially parallel to its longitudinal axis, and the sleeve 204 is axially cut into two pieces 204a, 204b such that each piece 204a, 204b of the sleeve 204 is provided with one piece 206a, 206b, 208a, 208b of each member 206, 208. Hereby, the device 202 can be applied around cables without being slipped on around the cables from one of the ends of the cables. This is suitable when the device needs to be exchanged due to wear on site. By the splitting each member 206, 208 into two pieces 206a, 206b, 208a, 208b and when the member pieces 206a, 206b, 208a, 208b of each member 206, 208 are received in a recess provided in the unit to provide for the member's 206, 208 locking engagement with said unit, the axial sliding of the two separate pieces 204a, 204b of the sleeve 204 is prevented. Otherwise, the features 204, 205, 207, 210, 212 of the second embodiment correspond to the features 104, 105, 107, 110, 112 of the first embodiment.

Figs 3a-3d show the first embodiment of the device 102 included in a first embodiment of the arrangement for protecting at least one cable extending between two units which are movable in relation to each other, according to the present invention. The arrangement includes the device 102 described above and a helical element 302 in the form of a helically shaped spring 302, for example formed from a wire made of metal (only a portion of the spring 302 is shown in the Figs.). The helical element 302 has several turns 304 along its longitudinal extension and is adapted to house and surround a length of at least one cable. The helical element 302, shaped as a helix, has two open ends 306, 404. The sleeve 104 of the device 102 is insertable into the inside of the helical element 302 through any of the open ends 306, 404. The radial extension 110, 112 of each member 106, 108 is adapted to engage between two turns 304 of the helical element 302.

In Fig. 3a, the sleeve 104 of the device 102 has been inserted into the helical element 302 via the first open end 306 by rotating the spring element 302 about its longitudinal axis in relation to the device 102. Through this rotation, the radial extensions 110, 112 of the members 106, 108 engage between the turns 304 of the helical spring 302. The length of the radial extension 110, 112 of each member 106, 108 exceeds the distance between the inner diameter and the outer diameter of the helical element 302. In Figs. 3b-3d, the device 102 also comprises a first embodiment of an attachment arrangement for attaching the device to a unit. The attachment arrangement comprises an intermediate sleeve 308, as illustrated in Fig. 3b, and an attachment element 312 as illustrated in Fig. 3d. The intermediate sleeve 308 is for example made from a plastic material, which has been applied around the sleeve 104 with the members 106, 108, and the helical element 302, such that the helical element 302 rests between the sleeve 104 and the intermediate sleeve 308. The intermediate sleeve 308 is provided with two recesses in the form of two through holes 309 adapted to receive and be engaged by the two members 106, 108 of the device 102. The intermediate sleeve may be made from two half sleeves that mounted over the sleeve 104 from the respective sides of the two members 106, 108.

Fig. 3c shows the device 102 in engagement with the helical element 302 and where a portion of the intermediate sleeve 308 is cut away for illustrative purposes. Here, it is shown in detail how the members 106, 108 of the device 102 have engaged between the turns 304 of the helical element 302. The sleeve 104 has an axial extension adapted to cover at least three turns 304 of the helical element 302. The outer diameter of the sleeve 104 is slightly larger than the inner diameter of the helical element 302, whereby the sleeve 104 is adapted be snug-fitted inside the helical element 302. The sleeve 104 of the device 102 is adapted to rest against an inner circumferential rim 310 provided on the inside of the intermediate sleeve 308. The helical element 302 is securely locked to the intermediate sleeve 308 by means of the device 102. If the helical element 302, in the position shown in Fig. 3c, is rotated in one direction about its longitudinal axis, the helical element 302 is further tightened around the sleeve 104 of the device 102 since further axial movement in the direction towards the device 102 is blocked by the inner circumferential rim 310, and if the helical element 302 is rotated in the second direction about its longitudinal axis, the abutment between the helical element 302 and the intermediate sleeve's 308 inner surface prevents this rotation. Fig. 3d shows the attachment element 312 adapted to be anchored to said unit. The attachment element 312 is provided with means for locking the members into engagement, and these means are in the form of recesses 313, shaped as through holes, each one of the recesses 313 being adapted to receive and retain a member 106, 108. Said attachment element 312 is here in the form of a frame in- eluding two frame parts 314, 316 pivotally attached to each other and adapted to surround and engage around the intermediate sleeve 308, such that the intermediate sleeve 308 is snugly rested within the attachment element 312. Alternativley, the two frame parts may be mounted together by screwing. The interior of the attachment element 312 and the exterior of the intermediate sleeve 308 are designed to allow the intermediate sleeve 308 to rotate about the aligned longitudinal axes w-w of the two members 106, 108. This is achieved by designing part of the exterior of the intermediate sleeve 308 as an arced surface and the interior of the attachment element as a corresponding arced surface and thus providing a ball and socket joint function. Each member 106, 108 is adapted to be rotatable about its longitudinal axis w in relation to the attachment element 312 and the unit to which the attachment element 312 is attached, and thereby the intermediate sleeve may pivot or tilt around the axis w.. The attachment element 312 is adapted to axially lock the device 102 in relation to the attachment element 312. The device 102 with its attachment arrangement forms, together with the helical element 302, a first embodiment of the arrangement for protecting at least one cable extending between two units which are movable in relation to each other, according to the present invention, as illustrated in Fig. 3d.

Figs 4a and 4b show the device 102 comprising a second embodiment of an attachment arrangement for attaching the device to a unit, and included in a second embodiment of the arrangement for protecting at least one cable, according to the present invention. Here, there is no intermediate sleeve. The sleeve 104 of the device 102 has been inserted into the inside of the helical element 302 through the second open end 404 of the helical element 302. The attachment arrangement comprises an attachment element 402, in the form of a frame having two opposite recesses 406, 408 in the form of through holes adapted to receive and retain a member 106, 108 of the device 102. This attachment element 402 is also adapted to axially lock the device 102 in relation to the attach- ment element 402, and each member 106, 108 is adapted to be rotatable about its longitudinal axis in relation to the attachment element 402 allowing the device 102 to rotate to a limited degree in a plane perpendicular to the longitudinal axis of the sleeve 104. The attachment element 402 is provided with a base 410 having through holes for guiding cables therethrough. Both attachment arrangements 308, 312, 402 are provided with means or elements for attaching the attachment element 312, 402 to a unit.

Fig. 5 shows a partial schematic perspective view illustrating an industrial robot having a first unit 502 and a second unit 504 which are movable in relation to each other. The second unit 504 is rotatable about a first axis y-y in relation to a third unit 506, and also in relation to the first unit 502. The second unit 504, together with the third unit 506, is also rotatable about a second axis z-z in relation to the first unit 502. Between the first and the second unit 502, 504, several electric cables 508 extend inside and along a helical element 302 (schematically illustrated in Fig. 5) included in an arrangement for protecting said cables 508. Since the second unit 504 is continuously moving about said two axes y-y, z-z, the cables 508 would repeatedly come into contact with at least the first unit 502 if not protected by the helical element 302. The arrangement further includes two devices 102 of the first embodiment, where one of the devices 102 locks the helical element 302 to the first unit 502 via a first attachment element 312, forming part of an attachment arrangement according to the first embodiment and attached to the first unit 502, and the second device 102 locks the helical element 302 to the second unit 504 via a second attachment element 402, according to the second embodiment of the attachment device and attached to the second unit 504. Embodiments of the first and second attachment arrangements have been described above.

By the arrangement and the devices according to the present invention, an efficient locking of the helical element to the two units is provided, and the cables are efficiently protected from wear. According to a further embodiment of the present invention, the device can be adapted to join two separate helical elements. Two devices as described above, without attachment arrangement, are then joined to form one single unit, which unit then presents a sleeve provided with at least four members, whereby two helical elements of a short length can be efficiently joined to form one longer helical element.

It is to be understood that the above-described embodiments can be modified in various ways and applied in other applications without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A device (102; 202) for locking a helical element (302) to a unit (502, 504), the helical element (302) having several turns (304) along its longitudinal exten- sion and being adapted to house and surround a length of at least one cable (508), which device (102; 202) comprises a rigid hollow sleeve (104; 204) defining a longitudinal axis (x-x) and being insertable into the inside of the helical element (302), and the sleeve (104; 204) is adapted to surround a longitudinal extension of the at least one cable (508), characterized in that the device (102; 202) com- prises at least two members (106, 108; 206, 208) each comprising a radial extension (1 10, 1 12; 210, 212) on the outside of the sleeve (104; 204), in that each radial extension (110, 112; 210, 212) extends substantially radially in relation to the longitudinal axis of the sleeve (104; 204) and is adapted to engage between two turns (304) of the helical element (302), in that the members (106, 108; 206, 208) are spaced apart in the circumferential direction, and in that the members (106, 108; 206, 208) are adapted to be locked into engagement with said unit (502, 504).

2. A device according to claim 1 , characterized in that the sleeve (104; 204) has an axial extension adapted to cover at least two turns (304) of the helical element (302).

3. A device according to claim 1 or 2, characterized in that the outer cross-section of the sleeve (104; 204) is substantially circular.

4. A device according to claim 3, characterized in that the outer diameter of the sleeve (104; 204) is slightly larger than the inner diameter of the helical element (302), whereby the sleeve (104; 204) is adapted be snug-fitted inside the helical element (302).

5. A device according to any of the claims 1 to 4, characterized in that the inner cross-section of the sleeve (104; 204) is substantially circular.

6. A device according to any of the claims 1 to 5, characterized in that the length of the radial extension of each member (106, 108; 206, 208) exceeds the distance between the inner diameter and the outer diameter of the helical element (302).

7. A device according to claims 1 to 6, characterized in that the two members (106, 108; 206, 208) are situated substantially diametrically opposite to each other in relation to the sleeve (104; 204).

8. A device according to claim 7, characterized in that each member (106, 108; 206, 208) defines a longitudinal axis w, and in that the longitudinal axes of the two members (106, 108; 206, 208) are essentially in alignment with one and the same diameter of the sleeve (104; 204).

9. A device according to claims 1 to 8, characterized in that each of the two members (106, 108; 206, 208) defines a longitudinal axis w and is adapted to be rotatable about its longitudinal axis in relation to said unit (502; 504) when locked into engagement therewith.

10. A device according to any of the claims 1 to 9, characterized in that the members (106, 108; 206, 208) are anchored to the sleeve (104; 204).

11. A device according to any one of claims 1 to 10, characterized in that each of the two members (206, 208) is split into two pieces (206a, 206b, 208a, 208b) in a plane substantially parallel to its longitudinal axis, and in that the sleeve (204) is axially cut into two pieces (204a, 204b) such that each piece (204a, 204b of the sleeve (204) is provided with one piece (206a, 206b, 208a, 208b) of each member (206, 208).

12. A device according to claim 11 , characterized in that the device (102; 202) comprises an attachment arrangement (306, 312; 402) adapted for attaching the device to the unit (502, 504).

13. A device according to claim 12, characterized in that the attachment arrangement comprises an attachment element (312; 402) adapted to be anchored to said unit (502, 504), the attachment element (312; 402) being provided with means for locking the members (106, 108; 206, 208) into engagement with the unit.

14. A device according to claim 13, characterized in that the attachment element (312; 402) is adapted to axially lock the device (102; 202) in relation to the attachment element (312; 402).

15. A device according to any of the claims 11 to 14, characterized in that the attachment arrangement comprises an intermediate sleeve (308) applicable around the rigid hollow sleeve (104) and the helical element (302), and provided with holes (309) adapted to receive and be engaged by the two members (106, 108), and the intermediate sleeve being rotatably mounted in the attachment element (312), around the aligned longitudinal axes (w) of the two members.

16. An arrangement for protecting at least one cable (508) extending between two units (502, 504) which are movable in relation to each other, which arrange- ment comprises a helical element (302) having several turns (304) along its longitudinal extension and being adapted to house and surround a length of at least one cable (508), and a device (102; 202) for locking the helical element (302) to one of the units (502, 504), characterized in that the device (102, 202) comprises the features mentioned in any of the claims 1 to 15.

17. An apparatus comprising two units (502, 504) which are movable in relation to each other, between which units (502, 504) at least one cable (508) extends, and an arrangement for protecting said at least one cable (508), characterized in that the arrangement comprises the features mentioned in claim 16.