Electrical connector for connecting at least two electrical conductors

The present invention relates to an electrical connector of the type comprising: - a first connector part and a second connector part movable one toward the other to connect conductors accommodated between the first and second parts;

- a screw and nut assembly for driving the first and second parts toward each other; and - tightening control means to avoid tightening the screw and nut assembly above a predetermined tightening torque.

It is desirable to use tightening control means to ensure proper electrical connection and avoid damages caused to the conductors or to the connector itself. It is possible to use a screw having a driving head and a threaded shank connected by a shear section adapted to shear at the predetermined tightening torque. The shearing of the shear section indicates to the operator that the predetermined tightening torque is attained.

Nevertheless, such screws are expensive to produce as compared to conventional screws.

An object of the invention is to provide an electrical connector having tightening control means that is simple and can be obtained at low cost.

To this end, the invention proposes an electrical connector of the abovementioned type, characterized in that the tightening control means comprise releasable rotational locking means adapted to rotationally lock one of the screw and the nut with regard of one of the first and second parts about the axis of the screw and nut assembly and to release said rotational locking means upon reaching said predetermined tightening torque.

Different embodiments of the electrical conductor may comprise any of the features of claims 2-7, individually or any technically feasible combinations.

The invention will be better understood on reading the following description which is given by way of example only and with reference to the appended drawings in which:

- Figure 1 is a diagrammatic exploded perspective view of an electrical conductor according to the invention;

- Figure 2 is a lateral elevation view of the connector of Figure 1 ; and

- Figures 3 - 7 are lateral cross-section views of electrical connectors according to alternative embodiments of the invention.

The electrical connector 2 shown on Figures 1 and 2 comprises an upper part 4 and a lower part 6 movable one relative to the other, and a screw and nut assembly 8 for driving the parts 4 and 6 toward each other along a clamping axis Z.

The assembly 8 comprises a screw 10 and a nut 12. The screw 10 has a driving head 14 for engagement with a driving tool, and a threaded shank 16 for engagement with the nut 12.

Each of parts 4 and 6 has an electrically insulating body respectively 18 and 20, and a pair of electrically conductive contacts 22 disposed on a front face 24 confronting the other body 18, 20.

Each face 24 has a rectangular general shape and is substantially perpendicular to axis Z.

Each face 24 has two parallel spaced apart grooves 26 extending between opposed edges 28, 30 (Figure 1) of said face 24 along a direction A.

Each groove 26 of a face 24 and a confronting one of the grooves 26 of the other face 24 define between them a channel for accommodating a conductor 32, 34 (Figure 2) between the parts 4 and 6.

Each face 24 has a pair of housings 36 (Figure 1 ), each housing 36 being adapted to accommodate one of the contacts 22.

Each contact 22 has two end portions 38, preferably provided with prongs, connected by a central portion 40, each of the end portions 38 protruding in one of the grooves 26 of the face 24 accommodating said contact 22.

Each of bodies 18 and 20 is provided with a through bore respectively 42 and 44 extending along axis Z for accommodating the shank 16.

The bore 42 opens on a rear face 46 of body 18 opposed to body 20 into a recess 48 of body 18 adapted to accommodate the nut 12 along axis Z.

The recess 48 has a lateral wall 50 adapted for rotational engagement about axis Z with the nut 12, whereby the nut 12 received into the recess 48 is in rotational engagement with the body 18.

As illustrated on Figure 2, the screw 10 is inserted through the bores 42 and 44, such that the driving head 14 is located on the side of body 20 opposite to body 18 and an end portion 52 of the shank 16 opposed to the driving head 16 protrudes out of the bore 42 opposite to body 20. A washer 54 is optionally interposed between the driving head 14 and the body 20. The nut 12 is screwed on the end portion 52.

In operation, two conductors 32, 34 to be connected one with the other are introduced laterally in the accommodating channels defined between parts 4 and 6. The nut 12 is engaged in the recess 48 to abut a bottom 56 of said recess 48, whereby the nut 12 is in rotational engagement, with the body 18 about the axis Z of the screw 10, i.e. is rotationally locked in the boby.

The driving head 14 is rotated about axis Z until it abuts the body 20. The driving head 14 is further rotated to drive the bodies 18 and 20 toward each other until the end portions 28 of the contacts 22 contact the conductors 32, 34. Each contact 22 connects the two conductors 32, 34.

The prongs are advantageous to penetrate optional electrically insulating sheaths of the conductors 32, 34. In a known manner, the contact 22 are optionally covered with electrically insulating cleats 57 (Figure 1) for ensuring watertight contact and electrical isolation with the conductor 32, 34. The body 18 and the recess 48 are designed such that the lateral wall 50 is deformed upon reaching a predetermined tightening torque, whereby, after deformation, the rotational engagement about axis Z between the nut 12 and the body 18 is released. Further rotation of the driving head 14 does not increase the tightening of the clamping assembly 8. The operator is informed that the predetermined tightening torque has been reached.

The recess 48 thus forms releasable rotational locking means between the nut 12 and the body 18 enabling to control the tightening of the assembly 8 to avoid tightening the assembly 8 above the predetermined torque. The recess 48 can be obtained easily and at low cost, for example during molding operations of the body 18 made of plastic material.

The predetermined tightening torque depends namely on the hardness of the material of the body 18, the shape and diameter of the lateral wall 50, the shape and diameter of the nut 12, and the height h of the recess 46. For example for a nut 12 having a diameter of 8mm between opposite faces of its hexagonal shape, if h=2mm and the hardness is 95MPa, the maximum torque is about 3,4 N.m.

To obtain a desired predetermined torque, it is possible to modify one or several of the above-mentioned parameters by successive steps until the rotational engagement is released at the desired predetermined tightening torque.

For example, the predetermined torque increases as the height h increases, as long as the height h is inferior to the height H of the nut 12. The predetermined torque increases as the hardness of the material of body 18 increases. The predetermined torque is preferably inferior to 10 N.m.

In a known manner, the bore 44 is preferably conical to enable tilting of parts 4 and 6 on relative to the other, for example in case the conductors 32, 34 are of different diameters.

The embodiment shown on Figure 3 differs from the embodiment of Figures 1 and 2 in that the nut 12 is accommodated in a recess 58 of a coupling member 60 which is single-piece with the body 18, and connected to the body 18 by a weakened shear portion 62 of lower thickness adapted to shear at the predetermined tightening torque.

In operation, the nut 12 is in rotational engagement with the body 18 via the coupling member 60. The screw 10 is rotated until shearing of the shear portion 62, whereby the rotational engagement of the nut 12 and the body 18 is released.

The coupling member 60 and the shear portion 62 are easily obtained, e.g. during molding operations of the body 18 made of plastic material.

The alternative embodiments illustrated on Figure 4 and 5 differs from that of respectively Figure 2 and 3 in that the positions of the screw 10 and the nut 12 are inverted, whereby the screw 10 is rotationally engaged with, i. e. locked into, the body 18.

In operation, the tightening of assembly 8 is effected by rotating the nut 12 until the rotational engagement between the body 18 and the screw 10 is released. The embodiment shown on Figure 6 differs from the embodiment of

Figures 1 and 2 in that the nut 12 is single-piece with the body 18 and is connected to the body 18 by a shear portion 63 of reduced thickness adapted to shear at the predetermined torque.

The nut 12 and the shear portion 63 are easily obtained, e.g. during molding operations of the body 18 made of plastic material.

In operation, the tightening of assembly 8 is effected by rotating the screw 12 until shearing of the shear portion 63.

Optionally, it is possible to provide at least one of the screw and the nut, namely the one which is not in rotational engagement with one of the parts of the connector, with additional tightening control means adapted to inform an operator that another second predetermined torque is attained.

For example, the embodiment of Figure 7 differs from the embodiment of Figure 4 in that the nut 12 has a main internally threaded portion 64 adapted to be screwed on the shank 18 and an additional tubular driving portion 66 connected to the threaded portion 64 by a shear section 68 of reduced thickness adapted to shear at a second predetermined torque inferior to the first predetermined torque transmittable between the body 18 and the driving head 14 received in the recess 48.

For low tightening applications, the operator rotates the portion 66, whereby the shear portion 68 will shear upon reaching the second predetermined torque, thus informing the operator of reaching said second tightening torque. For higher tightening applications, the operator rotates the portion 66 to be informed of reaching the first predetermined torque.

In such a case, the releasable rotational locking means between the screw 10 and the body 18 form additional tightening control means obtained easily and at low cost for enhancing the tightening control capabilities of the connector 2.