This application claims priority under 35 U.S.C. §119 to Italian Patent Application No. MI2015A000152 filed Feb. 5, 2015, the entire content of which is hereby incorporated by reference herein.
The present subject matter relates to a switchboard terminal block for connecting ground electric wires to a corresponding common reference point.
It is known, in the technical sector relating to the production of switchboards for the wiring of electrical installations, to use terminal blocks designed to be mounted on associated supports and to provide on the front side access to the retaining means—normally of the screw or spring type—for electric wires to be connected in order to ensure continuity of the various sections of the electric circuit. The continuity achieved by inserting inside a special seat, accessible from the front, movable contact elements such as protection fuses, electric circuit breakers or jumpers for connecting together two adjacent terminal blocks. It is also known that at least one of the terminal blocks of the switchboard must be used for the connection to ground of the respective wires of the circuit.
According to the prior art such a ground connection is obtained by means of terminal blocks, a conductor lamina of which is electrically connected to the DIN rail supporting the terminal block assembly.
DE 44 09 206 C1 describes a grounding conductor element.
The technical problem which is posed, therefore, is that of providing a terminal block, in particular of the type used in switchboards for wired circuits, which allows the user to perform the ground connection of the associated ground wires, by means of DIN support rails, in an easy, reversible and safe way, while maintaining the necessary conductive capacity for the protection and safety of the system installed. In connection with this problem, this terminal block should maintain the standard dimensions imposed by the connections and should be easy and inexpensive to produce and assemble.
These results are obtained according to the present subject matter by a grounding conductor element for switchboard terminal and by a terminal block for grounding electric wires.
Further details may be obtained from the following description of a non-limiting example of embodiment of the present subject matter, provided with reference to the accompanying drawings, in which:
As shown in
The substantially vertical shaped body 120 extends in the longitudinal direction X-X. The substantially vertical shaped body 120 includes a first substantially vertical body section 121, a second section 122, and a substantially vertical third section 123. The first substantially vertical body section 121 includes an edge 121a-situated at the top according to the layout shown in the figure—for connecting in the transverse direction Y-Y to a longitudinal edge 110a of the lamina 110 with which it forms one piece. The second section 122 is inclined with respect to the vertical section 121 from the top downwards and from the edge 110a towards the free edge 110b of the lamina 110 at a suitable angle Q. The substantially vertical third section 123 has its top edge connected to the second inclined section and includes a free bottom edge 123a for resting on the top surface of both folded flanges B1,B2 of a rail B, by means of a first edge section 123a1 and a second edge section 123a2. First edge section 123a1 and second edge section 123a2 are situated opposite each other in the longitudinal direction X-X and aligned in the vertical direction Z-Z for conductively resting on a respective one B1;B2 of the flanges of the rail B. The third section can be arranged in a vertical plane within the width of the lamina 110 in the transverse direction Y-Y, and can be substantially parallel to the free edge 110b of the lamina 110, opposite to that 110a connected to the first section 121.
The third section 123 of the conductor element includes a first end 124 and a second end 125. The first end 124 is proximal to and integral with the first section 123a1 of the edge 123a and the bottom edge 124a of which has a first tooth 124b projecting beyond the resting edge 123a in the vertical direction Z-Z and extending in the longitudinal direction X-X and inwards and designed to engage with one B1 of the two folded flanges B1,B2 of a DIN-standard rail B.
The second end 125 is opposite to the first end 124 proximal to and integral with the second edge section 123a2. The second end 125 has, from the top downwards (with reference to
Overall, the end 125 of the conductor element according to the present subject matter forms an engaging and retaining means for a flat-lamina spring 130. The flat-lamina spring 130 has a head 131 and two flat-pin legs 132. The head 131 includes an opening 131a for coupling with the pin 127 of the engaging end of the conductor element. The two flat-pin legs 132 are separated by an interspace 132a. The two legs can have a respective free end forming a tongue 132b inclined outwards at a suitable angle, for facilitating engagement with the rail B and for allowing operation thereof for disengagement from said rail.
As shown in
Pin 127 may be riveted so as to ensure the fixing and stability of the coupling. In order to perform engagement with the DIN rail it is sufficient to exert a pressure on the spring so as to produce a resilient deformation of the legs which, reacting against the contact surface formed by the third edge 125c, are deformed outwards so as to allow engagement, facilitated by the inclination of the free ends of the flat-pins. The shaped body 120, once the spring engages with the engaging end 125 of the body, arranges with three engaging points respectively corresponding to the point of engagement of the tooth 124b with the rail B and the contact points of the legs 132 pressing on the said rail. This produces a reaction, which generates a contact force both on the tooth 126 of the contact end 125 and on the tooth 124a of the opposite end 124, as well as between the sections 123a1, 123a2 of the flat resting edge 123a and the top surfaces of the flanges B1,B2 of the rail B, and also between the flat-lamina spring 130 and the respective folded edge of the said rail B.
The three engaging points also ensure both static planarity, once engagement has been performed, and dynamic planarity, during deformation of the legs 132 when performing engagement or disengagement, ensuring correct resting of the end sections of the resting edge 123a on the respective flanges of the rail B, with consequent use of the entire cross-section of the third vertical body section for electrical conduction, of a high conductive contact surface area on the rail B for discharging to earth, as well as stable and easy positioning of the grounding body 120 on the said rail B.
Applying pressure on the flat-pin elements in the opposite direction, outwards, produces an opposite deformation of the legs of the spring, which allows easy disengagement of the grounding element from the rail.
According to a preferred embodiment of the present subject matter, the longitudinal lamina 110 has a central through-opening 111 in the vertical direction Z-Z. The opposite free ends of the lamina 110 can form a tip 115 inclined upwards (
Preferably, each tip 115 has an incision 115a designed to engage with a corresponding relief 18a in the seat 18 in order to axially retain the lamina when it undergoes an axial deformation owing to the thrust exerted in the vertical direction by the screw of the means for retaining the wire 2.
The present subject matter also relates to a switchboard terminal block suitable for grounding the grounding conductors connected to it and provided with a grounding conductor element according to the present subject matter and described above.
In detail, the grounding terminal block includes an insulating body 10, which forms the container of the grounding conductor element and of means 50 for retaining the free end 2a of electric wires 2. For the sake of convenience of description and with reference to the directional layout shown by way of example, a bottom part corresponding to the part for engagement with a DIN rail B fixed to the electric switchboard, not shown, and a top part visible to the user, opposite to the bottom part, will also be assumed. During use, the top part will correspond to the front visible side of the terminal block mounted on the DIN rail.
In greater detail, insulating body 10 has a frame 11 substantially in the form of a closed ring and formed so as to define at least one front end side 11a and at least two respective flanks 11b for inserting wires 2 arranged opposite to each other in the longitudinal direction X-X.
The body 10 has, formed inside it, at least one pair of seats 13 and a bottom seat 60. The one pair of seats 13 is for housing the means 50 for retaining/releasing the wires. The bottom seat 60 is for housing the conductor body 120. Seat 60 is open at the bottom on the side for engagement with the rail B and is formed with a shape substantially matching that of the conductor body 120.
In greater detail a preferred seat 60 has a first top seat 61 and a second bottom seat 62. The first top seat 61 has a smaller dimension in the longitudinal direction X-X corresponding to the length of the top sections 121 and 122 of the body 120 and is bounded by vertical partitions 61a having a height in the vertical direction Z-Z substantially corresponding to the height of the said sections 121;122. The second bottom seat 62 is for housing the third body section 123, with top inner edges, which have at least one section 63a extending in the longitudinal direction X-X parallel to the top longitudinal edges 123c of the third section 123 of the body 120, so as to form reaction planes in the vertical direction Z-Z of the frame along the conductor body section 123 (and vice versa) during engagement/disengagement. The convex inner surfaces 64 at the longitudinally outer ends of the edges 63 are formed to correspond to the outer edges of the body 120. In particular, a first surface is parallel to the first edge 125a and extends in the vertical direction as far as the free ends of the legs of the flat-lamina spring, while the opposite inner surface complements the outer surface of the end 124 with tooth 124b.
The top wall 11a of the frame 11 may also be provided with (see
Each lateral flank 11b of the frame 11 is provided with a respective opening 17 communicating with a respective seat of the seats for housing the retaining/releasing means 50 for introducing the wire 2 in the longitudinal direction X-X. In the example shown in
Although not shown, it is envisaged that the means for retaining the wire 2 may be of the spring type.
As shown, the laterally open terminal block 10 is assembled by: inserting inside it (in the vertical direction Y-Y) the grounding element according to the present subject matter so that the opposite inclined tips 115 of the lamina 110 and the body 120 enter into the respective seats 18,60 of the insulating body 10 of the terminal block; and the means 50 for retaining the wire 2 inside the respective seat 13; closing the terminal block with a cover, not shown; inserting the wires 2 inside the respective insertion seats 17 and operating the actuating screw of the retaining means so as to grip the said wires against the conductor lamina; and inserting any further circuit elements inside the respective seats.
Owing to the particular arrangement of the second engaging end 125 and the spring 130 connected to it, the assembled terminal block may be easily engaged/disengaged with/from the DIN rail merely by means of pushing/pulling in the vertical direction Z-Z.
The teeth 19 with respective seat 19a are designed to receive corresponding projections 519 projecting outwards in the longitudinal direction X-X and formed in the bottom part of the frame 511 of an auxiliary terminal block 500 having lengthwise dimensions in the axial direction X-X smaller than those of the grounding terminal block.
The longitudinal dimension of the auxiliary upper-tier terminal block 500 is such as to leave exposed the hole 13a for access to the screw for actuating the means 50 for gripping the bottom wires 2 against the conducting lamina 111.
The joining together in the transverse direction Y-Y of the two frames 11 and 511 of the terminal blocks produces an assembly with two tiers, i.e. upper tier and lower tier—according to the non-limiting directional layout shown in the figure—suitable for housing a two-tier grounding element such as that shown in
The upper-tier terminal block 500 has a structure and component parts similar to those of the bottom terminal block and is therefore not described in detail.
It is therefore clear how the grounding conductor element for switchboard terminal blocks according to the present subject matter allows easy, rapid and safe reversible connection with the flanges of a DIN switchboard rail. In addition, the terminal block according to the present subject matter provided with this grounding element may in turn be easily handled by the user in a safe, repeatable and easy manner for engagement/disengagement with/from the DIN rail.
As used above and assuming solely for easier description and without a limiting meaning a set of three reference axes, respectively extending in a longitudinal direction X-X, corresponding to a lengthwise dimension of the grounding conductor element, transverse direction Y-Y, corresponding to a width or thickness of the grounding conductor element, and vertical direction Z-Z, corresponding to a heightwise dimension of the grounding conductor element according to the present subject matter.
Number | Date | Country | Kind |
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MI2015A000152 | Feb 2015 | IT | national |