A CLAMPING DEVICE

Abstract: A clamping device, such as a grounding clamp for electrical cables, comprising a contact section adapted to be attached to a conductive section by means of a clamping part (3) by turning a switch (4) supporting the contact section, the clamping part being connected to a shaft section (5), which is displaceable in relation to the switch and adapted to be gripped and hold by means of a gripping device (6) including a displaceable tightening part (7) arranged to achieve a gripping during displacement of the shaft section by means of against it acting contact devices (8) included in the gripping devices, the shaft section during a displacement of the tightening part and thereby the clamping part is arranged to be displaced. The device is especially characterized in that said contact devices (8) include at least one cylinder (9) with its axial direction arranged running preferably crosswise to the shaft section (5) axial direction and by means of the tightening part (7) being pressed against a plane surface (10) of the shaft section.

Description: A Clamping Device The present invention relates to a clamping device such as a grounding clamp for electrical cables comprising a contact sec¬ tion adapted to be attached to a conductive section by means of a clamping part by turning a switch. Clamping devices of substantially this type are already known in the art. According to such a known device the clamping part is supported by a shaft section nonrotateably but displace- ably connected with the switch and adapted to be gripped and fixed by means of a gripping device, said device comprising a displaceable tightening part adapted to radially during displace¬ ment move balls, these then being arranged to radially actuate a the shaft section circumsizing slotted sleeve for gripping the shaft section, the shaft section, the sleeve and the tightening part simultaneously being displaced during a further turning of the switch. Such devices known in the art are effected by substantial disadvantages of a e.g. security effecting nature. Thus, there is wear occuring in the contact area between the sleeve and the shaft section resulting in that the possibilities decrease to keep the shaft section- fixed by means of friction. This implies that the electrical clamp device contact with the contact section is substantially impaired. Moreover, the slotted sleeve is expo¬ sed to fatigue stresses and can break, this also implying a bro¬ ken contact with the ground, the shaft section then not further being fixed in an appropriate way. Furthermore, the design with a sleeve and balls is not adapted to break ice formations, etc. present in a nordic environment with a risque for a lost func¬ tion. The present invention relates to a clamping device not in¬ volved with the technical insufficiencies of the art but fullfil- ling highly security demands and moreover offering advantages in manufacturing. Thus the Invention relates to a clamping device according to the descriptive part of the attached claim 1. The device is cha¬ racterized especially of what is stated in the characterizing part of said claim. SUBSTITUTE SHEET The invention will be described in detail in connection with an execution example and the attached drawings, in which Figure 1 shows schematically a side view of a first embodiment of a device according to the invention in the longitudinal direction of a contact section adapted for gripping, Figure 2 shows the device of figure 1 in a view from the right side in figure 1, Figure 3 shows the device of figure 1 in a view from the left side in figure 1, Figure 4 shows a device mainly in accordance with figure 1 in a corresponding, partly cut view of figure 1, Figure 5 shows a detail of the device in figure 1 in the same view as in figure 1, Figure 6 shows a tightening part according to the invention in a view in its axial direction and in a corresponding top view of figure 4, Figure 7 shows a section A-A of figure 6, Figure 8 shows an axial section of a positioning ring according to the invention, and Figure 9 shows a section B-B of figure 8, Figure 10 shows a cylinder according to the invention for a con¬ tact with a shaft section when gripping the shaft section cross¬ wise to its axial direction, Figure 11 shows a section in the axial direction of the upper switch part with its screw portion, Figure 12 shows a section in the axial direction of a ring threa¬ ded on the inside and adapted to cooperate with said screw por¬ tion, Figure 13 shows a section in the axial direction of a support ring according to the invention, Figure 14 shows a shaft portion according to the invention, sub- stantialy in form of a hexagonal rod crosswise to its longitudi¬ nal direction, and Figure 15 shows a section C-C of figure 14. In figures 1 to 4 is designated by 1 a by the clamping devi¬ ce circumsized contact area arranged to be tightened e.g. at a SUBSTITUTE SHEET contact section 2 indicated with a broken line in figure 1, by means of a clamping part 3, i.a. by a swith 4 supporting the con¬ tact area. By 5 is designated a shaft section, figures 14 and 15, being connected to the clamping part and displaceable in relation to the switch. The shaft section is arranged to be gripped and hold by means of a gripping device 6 comprising a displaceable tightening part 7 arranged to, during a displacement in the axial direction of the shaft section, provide a grip of the shaft sec¬ tion by means of against this acting contact devices 8 comprised in the gripping devices, the shaft section and thereby the clam¬ ping device being displaced during a displacement of the tighte¬ ning part. The contact devices incorporate at least one cylinder 9, figure 10, arranged with its axial direction mainly running crosswise to the shaft section axial direction and being pressed by means of the tightening part against a plane surface of the shaft section. According to preferred embodiments there are three cylinders 9 symmetrically arranged on the shaft section periphery, pthis part then preferably and substantially being provided by a hexa¬ gonal rod 11 providing a plane axially running surface 10 for each cylinder. The tightening part, figures 6 and 7, is then run¬ ning peripherically along the shaft section and comprises an the shaft section facing, substantially plane surface 12 for each cylinder, by which surface the cylinder is adapted to be displa¬ ced and pressed against the shaft section. The tightening part has a conical form on the inside and thus widens in the direction to said clamping part to be radially displaced by means of the existing cylinders during a displacement in the shaft section axial direction towards the clamping section. Moreover, according to preferred embodients the conically arranged plane surfaces 12 of the tightening part comprise an inclination of about 3 to 7 degrees, preferably 5 degrees, towards the axial direction of the shaft section and the tightening part. It is also preferred that the existing cylinders are kept positioned between the tightening part and the shaft section by means of a positioning ring 13 with an opening 14 for each cylin¬ der, through which opening the cylinder is adapted to act against SUBSTITUTE SHEET the shaft section. By 15 is designated a support ring arranged to keep the existing cylinders between the shaft section and the tightening part. By 16 is designated a spring arranged at the end of the positioning ring facing the clamping part, the positioning ring being adapted to be displaced towards the clamping part against a spring force during displacement of the tightening part and the cylinders, the spring 16 then acting on the support ring. According to the shown embodiment the portion 17 of the switch which is connected to the contact area comprises a screw portion 18 arranged to cooperate with an on the inside threaded ring 19 of the contact area, which screw portion is adapted to during a turning of the switch in a certain direction be screwed into the contact area and thereby displacing the tightening part. The ring 19 is arranged to be fixed in the contact area by means of at least one locking screw 20 or similar. Furthermore, the tightening part includes according to the invention a substantially plane surface 21 angled in relation to the shaft section axial direction and arranged to cooperate with a correspondingly angled support surface 22 of a hooking portion 23 incorporated in the contact area for tightening a contact sec¬ tion or similar. Thus the clamping part includes at least one lockcing portion 24 protruding from said contact surface 21 in the direction towards said support surface 22 and arranged to keeep said contact section or similar between said surfaces 21, 22. It is preferred to provide two locking portions 24, one pre¬ ferably in connection with each end of the clamping part seen in the longitudinal direction of the contact section and preferably at the portion 26 provided at the contact surface 21 nearest the switch, the distance between the locking portions being larger than the hooking portion length in the contact area longitudinal direction so that the contact surface of the clamping portion can be pushed against said support surface without being hampered by the locking portions. The locking portions are preferably provi¬ ded with a fillet 27 substantially adapted to the contact section at its side facing the support surface 22. Furthermore, the clamping part is provided with at least one but preferably two hoisting arms 28 at its upper from the switch SUBSTITUTE SHEET facing part, in this case one arm 28 situated on each side of the hooking portion to cooperate with a contact section or similar so that the clamping part and the shaft section are lifted to a clamping position when the device is hooked onto the contact sec¬ tion. Its is also preferred that the clamping part is rotatably connected to the shaft section. The contact section of the device is provided with suitable elements 29 for fastening a grounding cable 30 to the contact section. According to the shown embodiment the devices 29 include a bore 31 with a profiled inlet 32, figure 5, in which a correspon¬ ding contact element is arranged to be fitted and to be locked by a bolt on the opposed contact section side as to be seen in figu¬ res 1-5. The operation of the device according to the invention is substantially evident from what has been said above. The contact section is operated by the switch and is brought into engagement with a conductive section or similar in such a way that the hoo¬ king portion is moved across the conductive section and is intro¬ duced between said surfaces 21, 22, the clamping part being hois¬ ted by means of the arms 28 with a simultaneous displacement of the shaft section, which is freely displaceable and rotatable with the gripping device in a non active position, a non gripping position. To tighten the conductive section the switch is turned in a certain direction, here clockwise, in relation to the contact section, the tightening part by means of the screw portion is displaced towards the hooking portion and thus the cylinders are displaced radially to bear on the shaft section plane surfaces adapted for that purpose, by which the shaft section is gripped and hold so that the shaft section is displaced together with the tightening part etc. during a further turning of the switch and the bearing of the clamping part on the conductive section or similar is completed. The shaft section is gripped and hold by means of the friction between the cylinders and the shaft sec¬ tion. Turning the switch in the opposite direction the bearing is relieved and the tightening part etc. is restored to its inactive SUBSTITUTE SHEET position by means of the spring acting on the support ring. As should be evident from the foregoing the invention provi¬ des substantial advantages in comparison with what already is known in the art. Thus, the cylinders are acting directly on the shaft section with all their bearing length and thereby do not wear by their rolling contact the shaft section so that a grip¬ ping is aggreviated. Any hardened components, exposed to serious fatigue stresses, do not exist. By an adaptation of the tighte¬ ning part conical shape a self-locking action is provided for the cylinders between the shaft section and the tightening part so that a force acting towards the switch on the shaft section auto¬ matically increases the cylinder bearing pressure on the shaft section. The device fullfills substantially high security condi¬ tions. The invention has been described above in connection with some execution examples. Of course, further embodiments and minor changes and amplifications can be imagined without departing from the scope of the invention. Thus, the number of cylinders can be varied from one to two or several cylinders and the shaft section cross section can be adapted to the number of cylinders. The gripping devices can actually be adapted to other devi¬ ces than clamping devices for the here indicated purpose. Embodiments can also be imagined, where the cylinder axial direction is not running crosswise to the shaft section axial direction, but for example in parallel with the shaft section axial direction. According to a further embodiment supporting elements 33 are provided, being shown in broken lines in figure 4 arranged on the cylinder side facing from the clamping part 3 to prevent the cylinders to leave their intended position without being possibly automatically returned, if these are displaced towards the clam¬ ping part in a non intended order, for example, if the positio¬ ning ring 13 and the shaft section, the hexagonal rod are fixed to each other by ice formations. Said support element is here provided by a stop ring 33 arranged in a groove 34 indicated with broken lines in figure 8 at the end of the position ring 13 SUBSTITUTE SHEET facing from the clamping part 3, the stop ring protruding from the position ring mantle surface. The support element is also providing a bucker so that the positioning ring under the action from a spring force etc. acting in a direction from the clamping part can be freed from the shaft section 11. The support element can supposedly being part of the positioning ring 13. Thus, the invention is not restricted to the embodiments in¬ dicated above and can be varied within the scope of the invention provided by the attached claims. SUBSTITUTE SHEET

Claims: C L A I M S 1. A clamping device, such as a grounding clamp for electri¬ cal cables, comprising a contact section adapted to be attached to a conductive section by means of a clamping part by turning a switch, the clamping part being connected to a shaft section, which is displaceable in relation to the switch and adapted to be gripped and hold by means of a gripping device including a dis¬ placeable tightening part arranged to achieve a gripping during displacement of the shaft section by means of against it acting contact devices included in the gripping devices, the shaft sec¬ tion during a displacement of the tightening part and thereby the clamping part arranged to be displaced, characterized in that said contact devices (8) comprise at least one cylinder (9) with its axial direction arranged running preferably and substantially crosswise to the shaft section (5) axial direction and by means of the tightening part (7) to be pressed against a plane surface (10) of the shaft section. 2. A device according to claim 1, characterized in that three cylinders (9) are provided peripherically distributed along the shaft section being preferably provided by a hexagonal rod (11) offering a plane axially running surface (10) for each cylinder. 3. A device according to claim 1 or 2, characterized in that the tightening part is running peripherically along the shaft section and includes a substantially plane surface (12) facing the shaft section for each cylinder, by means of which surface the cylinder is intended to be displaced and pressed against the shaft section. 4. A device according to claim 1, 2 or 3, characterized in that the existing cylinders are kept positioned between the tightening part and the shaft section by means of a positioning ring (13) with an opening (14) for each cylinder, through which SUBSTITUTE SHEET opening the cylinder is intended to act against the shaft sec¬ tion. 5. A device according to claim 4, characterized in that the tightening part, the cylinders and the positioning ring are ar¬ ranged to be displaced againt a spring force when gripped. 6. A device according to claim 4, characterized in that a support ring (15) is provided to keep the existing cylinders be¬ tween the tightening part and the shaft section, a spring (16) then preferably acting on the support ring to provide said spring force. 7. A device according to claim 1, 2, 3, 4, 5 or 6, characte¬ rized in that the tightening part has a conical shape on the in¬ side and thus widens towards said clamping part (3) to radially displace existing cylinders during a displacement in the shaft section axial direction. 8. A device according to claim 4, characterized in that the in conical shape arranged, plane surfaces (12) of the tightening part present an inclination of about 3 to 7 degrees, preferably 5 degrees, towards the axial direction of the shaft section and the tightening part. 9. A device according to any one of the preceding claims, characterized in that the with the contact area connected part (7) of the switch (4) includes a screw portion (18) adapted to cooperate with an on the inside threaded ring (19) of the contact area, which screw portion is adapted to, during a turning of the switch in a certain direction, be screwed into the contact area and the tightening part is simultaneously displaced. 10. A device according to any one of the preceding claims, where said clamping part includes a substantially plane contact surface (21) which is angled in relation to the shaft section axial direction and arranged to cooperate with a correspondingly angled support surface (22) of a hooking portion (23) in the con¬ tact area to clamp a conductive section (2) or similar, characte¬ rized in that at least one locking portion is provided protruding from said contact surface towards said support surface and adap¬ ted to keep said conductive section or similar between said sur¬ faces (21, 22). SUBSTITUTE SHEET 11. A device according to claim 10, characterized in that two locking portions (24) are provided on the clamping part in the longitudinal or corresponding direction of the conductive section and preferably at the portion (26) of the contact surface nearest the switch, the distance between the locking portions being larger than the hooking portion length in the conductive section longitudinal direction so that the contact surface of the clamping section can be moved towards said support surface with¬ out being hampered by the locking portions. 12. A device according to claim 4, 5, 6, 7, 8, 9, 10 or 11, characterized in that supporting elements (33) such as a stop ring (33) are arranged at the positioning ring on the cylinder side facing from the clamping section as a stop and a bucker. SUBSTITUTE SHEET

Inventors: AHLDEN ULF HUGO LENNART, KARLSSON GERT TURE, AHLDEN, ULF, HUGO, LENNART, KARLSSON, GERT, TURE
Applicants: AHLDEN ULF HUGO LENNART, KARLSSON GERT TURE, AHLDEN, ULF, HUGO, LENNART, KARLSSON, GERT, TURE
Application year: 1995
Main classification: H01R11
IPC codes: H01R11