RECESS.

DESCRIPTION

The invention regards a cabling unit for grooved bus bars with T-shaped cavity. The cabling unit of the invention may be used for obtaining connections to grooved bus bars belonging to structures of various types.

Preferably, the cabling unit of the invention is most commonly used in electrical cabinets and switchboards where it is used for connecting electrical devices, such as for example switches, disconnectors or other devices, to the grooved bus bars with a T-shaped cavity for the distribution of the electric power.

The electric power distribution bus bars that are used in electrical cabinets and switchboards are constituted by shaped elements with longitudinal extension, each of which is provided with a T-shaped groove which traverses it lengthwise.

According to the prior art, special screws with hammer head are inserted in the groove for fixing - to the bus bars - the terminals of the electrical cables that supply the different components housed in the switchboard or cabinet, such as for example switches, disconnectors, deviators and other electrical devices. A distribution bus bar of the known type is represented by way of example in figure 1 , in which it is indicated in its entirety with A.

The bus bar is longitudinally traversed by the groove B, which is accessible through the longitudinal slot C and is configured to receive the screw D having the hammer head D1 provided with an elastic element D2.

When mounting the screw D, the operator holds it by the threaded shank D2, arranges it with the hammer head D1 aligned to the slot C and then inserts it into the groove B, as observable in figure 2.

In this configuration, the screw cannot be rotated given that, as observable, the lateral walls of the hammer head D1 counteract the walls of the slot C.

Rotating the screw requires forcing the hammer head D1 against the bottom of the groove B so that the compression of the elastic element D3 allows the hammer head D1 to fully enter into the groove B, as observable in figure 3, up to freeing the walls thereof from contact with the walls of the slot C.

In such position, the screw D can be rotated in the clockwise direction until it is arranged transversely to the slot C in the position observable in figure 4.

Once the rotation is completed, the screw D is released and the expansion of the elastic element D3 pushes the underhead of the screw D counteracting the inner surface of the groove B so that the screw remains constrained in the position observable in figure 5.

Thus, the screw D is self-supporting and the operator does not have to support it during fastening for cabling operations.

The presence of reliefs D4 arranged at the underhead, which counteract the wall of the slot C once the rotation has occurred, limits the amplitude of the rotation angle that can be imparted to the screw to 90° and serves as an end stop which prevents any further rotation of the screw D and guarantees the required reaction for fastening the bolt H.

The use of self-supporting screws with a hammer head has the advantage of facilitating the cabling given that, after insertion thereof into the grooves of the bus bars, they remain in position and the operator can work using both hands. Various types of self-supporting screws with a hammer head and provided with variously shaped elastic elements are available in the market, but they all reveal the known drawback lying in the fact that after being arranged in the self-supporting operating position in the groove B, an inadvertent counter- rotation in the anticlockwise direction easily returns them to the initial configuration of figure 3 in which they can project from the groove B.

As a matter of fact, the elastic element that guarantees the self-support of the screw does not provide - against the bottom of the groove B - a friction sufficient to effectively counteract a counter-rotation torsional moment, which may at times be inadvertently caused by the operator when operating the fastening tools.

The aim of the present invention is to overcome this drawback described now.

In particular, the object of the invention is to obtain a cabling unit with grooved bus bars comprising a self-supporting screw with a hammer head and configured to guarantee greater stability to the screw with respect to equivalent screws of the prior art.

Advantageously, the screw of the cabling unit of the invention reveals greater stability against counter-rotation with respect to the prior art.

The object is attained by a cabling unit according to the main claim to which reference shall be made.

Particular characteristics of the cabling unit of the invention are described in the dependent claims. The aforementioned object shall be more apparent from the description of the cabling unit of the invention, outlined hereinafter by way of non-limiting example, with reference to the attached drawings, wherein:

- figs. 1 to 5 represent different views and positions of an electric power distribution bus bar and the relative screw with a hammer head belonging to the prior art;

- figs. 6 to 8 represent different views of the cabling unit of the invention;

- figs. 9 and 10 represent different views of a detail of the cabling unit of the invention;

- fig. 9a represents a detail of fig. 9;

- figs. 1 1 to 18 represent different views and positions of the cabling unit of the invention, assembled to a respective grooved bus bar;

- figs. 13a, 14a, 17a and 18a represent enlarged details of the corresponding figures bearing the same number.

The cabling unit of the invention is represented in figures 6 to 8 where it is indicated with 1 in its entirety.

It is used for connection to grooved bus bars L observable in figures 1 1 to 18, preferably but not exclusively of the type adapted to transmit electric power, which are installed in electrical cabinets or switchboards.

It is however understood that the cabling unit 1 may be used for connection to grooved bus bars of any type and adapted for any use.

Each grooved bus bar L comprises a longitudinal cavity M accessible through a longitudinal slot N and the cabling unit 1 comprises a screw 2 having a threaded shank 3 provided with a hammer head 4 to which a shaped casing 6 configured to be received in the longitudinal cavity M is associated after insertion through the longitudinal slot N.

The threaded shank 3 is provided with two lateral reliefs 5, radially projecting and diametrically opposite to each other, which are arranged at the underhead surface 4a of the hammer head 4.

In the shaped casing 6 there is identified a shaped housing 7 configured to receive the hammer head, an elastic bottom 9 and a through opening 8 for the threaded shank 3 of the screw 2, arranged on the opposite side of the elastic bottom 9.

When the shaped casing 6 is arranged in the longitudinal cavity M along the slot N and the hammer head 4 of the screw 2 is arranged transversely to the slot N, as observable in figure 15, the elastic bottom 9 pushes the hammer head 4 so that the underhead surface 4a thereof counteracts the inner wall Q of the longitudinal cavity M opposite to the bottom P of the latter.

In this position, the screw 2 - with the entire cabling unit 1 - remains constrained and self-supported in the longitudinal cavity M.

According to the invention, the shaped casing 6 is provided with counteracting means 10 that are configured to cooperate with the lateral reliefs 5 and prevent the counter-rotation of the screw 2 when the hammer head 4 is arranged transversely to the longitudinal slot N.

As regards the shaped casing 6, besides the aforementioned elastic bottom 9, it comprises - in particular as observable in figures 9, 9a and 10 - two upper walls 11 opposite to the elastic bottom 9 and mutually coplanar and spaced, and two lateral walls 13, each of which connects the elastic bottom 9 to one of the aforementioned upper walls 11.

In this manner, the walls 11 and 13 and the elastic bottom 9 define - for the shaped casing 6 - a profile that substantially recalls the shape of the letter "C" and delimits the shaped housing 7 that receives the hammer head 4.

It should also be observed that the upper walls 11 have shaped ends 12 that are juxtaposed to each other and mutually define the through opening 8 for the screw 2.

In particular, in the shaped ends 12 there are the aforementioned counteracting means 10, each of which is defined by an undercut area 15 facing towards the shaped housing 7.

As observable in particular in figures 9, 9a and 10, the undercut area 15 is delimited by a counteracting wall 16 with which a respective lateral relief 5 comes to contact.

The counteracting wall 16 is orthogonal to the upper wall 11 and its height K' is lower than the thickness K of the respective upper wall 11 , so that the undercut area 15 is entirely comprised in the thickness K of the upper wall 11.

Thus, each shaped end 12 assumes a strip-like configuration with thickness K" equivalent to the difference between the thickness K of the upper wall 11 and the height K' of the counteracting wall 16.

In addition, each lateral relief 5 is received in the undercut 15 when the elastic bottom 9 of the shaped casing 6 is arranged in an arched fashion and in inoperative position. Each shaped end 12 also has a concave area 17 belonging to the surface of the corresponding upper wall 11 , so that the through opening 8 of the shaped casing 6, in particular observable in the plan view of figure 10, is defined by said mutually juxtaposed and spaced concave areas 17.

As regards the lateral walls 13, the length F of each of them is greater than the distance F' measured between the bottom P and the inner wall Q of the longitudinal cavity M so that the shaped casing 6, when housed in the longitudinal cavity M, remains constrained and aligned in the longitudinal slot N by contrast against the walls Na of the latter, as observable in particular in figures 13 to 15.

As regards the elastic bottom 9, it should be observed - particularly in figures 8 and 9 - that it comprises an elastic strip 9a, shaped to form a curved profile with the convexity 20 facing towards the upper walls 11 and thus towards the inside of the shaped housing 7.

In addition, it should be observed that the elastic bottom 9 also comprises two elastic membranes 9b each of which connects the elastic strip 9a to a corresponding lateral wall 13.

The elastic membranes 9b are arranged inclined with respect to the upper walls 11 and each of them intersects the lateral wall 13 corresponding thereto in an intermediate area.

In this manner, the elastic bottom 9 has an optimal elasticity so that it can be deformed and arranged according to the configuration represented in a dashed line in figure 9 when the operator forces the hammer head 4 against it to constrain the screw 2 to the bus bar L, as described below.

Operatively, when the user wants to constrain the cabling unit 1 to the bus bar L, he inserts the hammer head 4 of the screw 2 into the shaped casing 6 in the configuration observable in figure 1 1 and - through the longitudinal slot N of the bus bar L - arranges the shaped casing 6 with the screw 2 associated thereto in the longitudinal cavity M, as observable in axonometric view in figure 12 and in longitudinal sectional view in figure 13.

By applying a force S to the shank of the screw 2, the user forces the hammer head 4 against the elastic bottom 9, as observable in figure 14, so as to flatten it against the bottom P of the longitudinal cavity M.

In such position, as previously mentioned, the shaped casing 6 counteracts the walls Na of the longitudinal slot N while the lateral reliefs 5 of the screw 2 completely recede into the shaped casing 6, as observable in figure 14 and particularly in the detail of figure 14a.

As a matter of fact, the distance G measured between the upper walls 11 and the elastic strip 9a - when the latter is adherent to the bottom P of the longitudinal cavity M - is greater than the distance G' measured between the outer surface 4b of the hammer head 4 and the outer surface 5a of the lateral reliefs 5.

In this manner, the shaped casing 6 remains fixed in the position, the lateral reliefs 5 do not contrast against the counteracting walls 16 that delimit the undercut areas 15 of the shaped casing 6 and thus the screw 2 can be rotated in the clockwise direction, as observable in figure 16 and in figure 17, until it reaches the transversal position with respect to the longitudinal slot N in which, as observable in figures 18 and 18a, the screw 2 is released.

In such position, the thrust exerted by the elastic bottom 9, which returns to the initial arched position, pushes the underhead surface 4a of the hammer head 4 against the inner wall Q of the longitudinal cavity M, as observable in figure 15, thus guaranteeing the stability of the screw 2 in the attained position.

Figures 18 and 18a show that both the lateral reliefs 5 of the screw 2 remain constrained to the counteracting walls 16 that delimit the undercut areas 15 that house them and thus prevent the screw 2 from being inadvertently counter-rotated in the anticlockwise direction thus returning the entire cabling unit 1 to the initial unstable configuration represented in figure 12.

In addition, in the configuration of figures 18 and 18a, each lateral relief 5 also counteracts a respective wall Na of the longitudinal slot N, as observable in figure 15, and thus prevents any further rotation of the screw 2 in the clockwise direction and serves as a reaction element for the fastening of a bolt.

Thus, the operator may carry out all operations for fastening one bolt to the screw 2 with both hands free and thus not having to worry that the screw 2 may move from the attained position.

Thus, in the light of the above, it is clear that the cabling unit of the invention attains all preset objects.

In the executive step, the cabling unit of the invention may be subjected to modifications and variants not described and represented in the figures, all of which shall be deemed protected by the present patent should they fall within the scope of protection of the claims that follow.