Patent Description:
Insertion connection - also called insulation displacement connection or simply IDC - is widely used by industry in all areas where there is an electrical wire to be terminated/connected directly with a terminal. In this particular case, there is great demand for the use of insulation displacement connection systems in the automotive industry.

In particular, reference is made to enameled copper wires, i.e., wires covered with a layer of electrical insulation which must be removed from the ends of the wire to allow its electrical connection to the relevant terminal.

The insertion connection allows for an electrical connection which, combined with ease of use and application, makes it possible to replace the cleaning of the enameled wire and subsequent soldering.

In addition to increased convenience of use, the insertion connection also provides a "gas-tight" seal.

In other words, insertion connection is a viable alternative to traditional soldering and/or crimping systems because it allows simultaneous removal of the insulation layer and mechanical and electrical connection of the wire.

The main connection systems currently on the market will be analyzed below.

A first example according to the prior art, known to a person skilled in the art as a "splice," consists in joining two enameled wires by way of a permanent mechanical deformation process. The operation is completely manual and consists in inserting the enameled wires inside the terminal, known as the "splice", which is provided with a plurality of notches/points. By folding the side with the notches/points over the wires, the enamel is broken and the electrical connection between the electrical wires is achieved. In other words, by crimping the terminal on itself, the enamel of the wires is broken and they are electrically connected to each other.

Disadvantageously, this is a manual operation that requires different terminal sizes depending on the diameters of the wires to be connected. In addition, splice technology cannot be automated and is not recommended for "capillary" wires.

It should be noted that the term "capillary" means wires with a diameter comparable to that of a hair, that is to say, with a diameter of less than <NUM>.

A second example, described in <CIT> and <CIT>, consists of a combined system comprising a pocket and a terminal, wherein the enameled wire is inserted into the plastics pocket and is then attached at a special end.

The terminal is inserted inside the pocket by means of a special applicator and undergoes deformation against the pocket walls during the insertion process. In other words, the terminal is shaped by the pocket itself during its insertion inside the pocket. The terminal is provided with a plurality of notches/tips, facing the wire, which are suitable for breaking the enamel during insertion into the pocket. Upon completion of the insertion, the terminal is locked inside the pocket to ensure electrical contact between the wire and terminal.

Disadvantageously, this solution requires that the dimensional tolerances for the pocket be extremely small. In addition, the pocket is bulky and not easy to make; the size of the terminal also changes depending on the diameter of wire to be connected. Given the size of the system, its application remains limited to technical sectors where the need for miniaturization and reduction of the overall dimensions is not yet a priority.

An additional solution provided by the prior art is the crimp-and-solder terminal system. This system involves inserting the enameled wire inside a terminal tab which has special grooves in it. By closing the tab against the terminal and simultaneously soldering the tab against a wall of the terminal, the system is locked in place. This solution may also be automated; however, it is mainly used for "coarse" wires with high current transmissions.

Thus, the disadvantages of this system are the pre-shaping of the tab, which is necessary to prepare it for subsequent soldering, the soldering process itself, and the restricted application to "coarse" wire diameters.

A still further solution provided by the prior art is insertion connection systems, wherein the enameled wire is covered by the terminal fins during its insertion inside the terminal. Such systems are, for example, known from <CIT> and <CIT>. The limitation of use of these terminals and applications lies in the diameter of the wire used and the shape of the terminal. In fact, in the solutions from the prior art, the terminal fins enter over the wire, which is housed in a special seat/groove, and, for diameters below a certain size, the enameled wire must be held taut (in order to be able to allow the terminal to be used and ensure the position of the wire during the insertion process). In addition, such systems do not allow the use of wires that are too small because the force that the fins exert on the wire must still be less than the shear strength of the wire: this defines the minimum limit of enameled wire for the use of both terminals. In addition, the system, by its operation, cuts the enameled wire and reduces its cross section, compromising in some cases the application for products that are particularly stressed by thermal shock or vibration, such as in automotive applications.

Lastly, a final solution provided by the prior art is described in patent <CIT>, filed in the name of the same applicant, in which the mechanical insertion contact system provides an electrical connection between an enameled wire and a terminal inserted into a special seat. However, unlike the other systems, the enameled wire is wound at the end and beginning of its winding on a special pin positioned centrally at the insertion seat. The terminal is inserted over the pin, and during insertion the fins drag over the enameled wire and remove the enamel, allowing electrical contact with the copper wire. Given the special shape of these fins, they hold the wire taut once they are in position and ensure continuous electrical contact over time. This system covers a wide range of wires, even capillary wires, for example with a diameter of <NUM>.

Disadvantageously, even this solution may be too large for some products such as coils, where the wire range that is normally required is small, that is to say, the wire size-to-product ratio is extremely small.

Thus, the solutions listed above are still too bulky and fail to meet the miniaturization requirements that are gradually becoming increasingly important in the industrial world. In addition, there is a need for a displacement connection capable of connecting the enameled wires without reducing the current flow cross section, and of ensuring a reliable electrical "gas-tight" connection between the wire and the terminal over time, without being bound to the resistance of the wire to shear stress during terminal insertion and taking into account the dimensional production variables of the system components.

Therefore, the problem addressed by the present invention is that of providing a system for insertion connection that overcomes the disadvantages described with reference to the prior art.

These disadvantages and limitations are solved by an insulation displacement connection system according to claim <NUM>.

Other embodiments of the system according to the invention are described in the dependent claims.

Further features and advantages of this invention will become more apparent from the following detailed description of preferred, non-limiting embodiments thereof, in which:.

In the following description, elements common to the various embodiments represented in the drawings are indicated with the same reference numerals.

In said drawings, reference sign <NUM> has been used to denote an insulation displacement connection system, for example an "IDC"-type connection system, according to the invention as a whole.

Such an insulation displacement connection system <NUM> comprises a connection terminal <NUM>, a pocket <NUM> suitable for accommodating the connection terminal <NUM>, and an enameled wire <NUM> spirally wound and at least partly accommodated in said pocket <NUM>.

The pocket <NUM> comprises a pin <NUM> on which said wire <NUM> is wound.

Preferably, the pin <NUM> is made of a material belonging to the family of polymers.

The pin <NUM> is delimited by side walls <NUM>, <NUM> which support the enameled wire during the winding of the wire <NUM> onto the pin <NUM>. In addition, the pin <NUM> comprises a midplane M-M, and said midplane M-M is preferably also a plane of symmetry for the pocket <NUM>. In the present case, the pin <NUM> lies substantially along the plane of symmetry M-M.

The pocket <NUM> is frontally delimited by the pin <NUM>, at the back by a rear wall <NUM> and laterally by a pair of side guide walls <NUM>, <NUM> suitable for guiding the connection terminal <NUM> during the insertion thereof into the pocket <NUM>.

Preferably, these side guide walls <NUM>, <NUM> comprise respective bevels <NUM>; <NUM> to facilitate the entry of the terminal <NUM> inside the pocket <NUM>.

The connection terminal <NUM> is provided with a single tab <NUM> shaped to elastically intercept the pin <NUM> so as to exert an abrasive action on the enameled wire <NUM> during the insertion of the connection terminal <NUM> into the pocket <NUM> and so as to elastically bias the wire <NUM> to abut against the pin <NUM> upon the insertion of said terminal <NUM> into the pocket <NUM>, thus ensuring the electric connection between the single tab <NUM> and the wire <NUM>.

The single tab <NUM> comprises an outer side <NUM> suitable for intercepting the wire. Said outer side <NUM> has a shaped surface <NUM> which directly interfaces with the enameled wire. The single tab <NUM> further comprises a terminal midplane M'-M' suitable for being coplanar to the midplane M-M.

For example, the shaped surface <NUM> is obtained by an embossing operation so as to produce pockets suitable for interfering with the enameled wire <NUM>.

The pin <NUM>, the rear wall <NUM> and the pair of side guide walls <NUM>, <NUM> delimit a cavity <NUM> for accommodating the connection terminal <NUM>, in particular the tab <NUM>.

Advantageously, the pocket <NUM> has only one cavity <NUM>.

In an embodiment, the connection terminal <NUM> comprises a body <NUM> and the single tab <NUM>. The tab <NUM> extends from the body <NUM> so as to remain facing it.

The outer side <NUM> of the single tab <NUM> has, along the extension thereof, at least a partly curvilinear development having concavity directed towards the body <NUM> of the terminal <NUM>.

Preferably, the tab has an inner side <NUM> opposite the outer side <NUM>, where a reinforcing rib <NUM> is arranged to strengthen the tab <NUM> without compromising its elasticity.

According to one embodiment, the at least partially curvilinear development of the outer side <NUM> of the tab <NUM> has an arc of parabola shape.

In accordance with an embodiment, the tab <NUM> extends between a connection portion <NUM> and a free end <NUM>. Said connection portion <NUM> connects the tab <NUM> to the body <NUM> so as to allow the tab <NUM> to elastically bend, pivoting on the connection portion <NUM>, for example said connection portion <NUM> comprises an arc of circumference <NUM>.

Preferably, the at least partly curvilinear development of the outer side <NUM> is such as to increase the mutual distance between the tab <NUM> and the body <NUM>, moving from the connection portion <NUM> towards the free end <NUM> of the tab.

According to an embodiment, the tab <NUM> has, in the vicinity of the free end <NUM>, a development which is substantially parallel to body <NUM>.

In accordance with a preferred embodiment, the shaped surface <NUM> comprises a plurality of contact areas <NUM> alternated by a plurality of supporting areas <NUM>. The contact areas <NUM> comprise contact tips, for example alternating ridges and depressions, where said contact tips are obtained by molding and are suitable for breaking the enamel to allow the electrical connection between the wire <NUM> and the terminal <NUM>.

The supporting areas <NUM> are portions of smooth surface which are configured as supporting points for the wire <NUM>.

In an embodiment, the shaped surface <NUM> extends from the connection portion <NUM>, in particular from the arc of circumference <NUM>, up to the free end <NUM>.

Overall, the tab <NUM> has a shape that facilitates the insertion of the terminal <NUM> into its special pocket <NUM>, so that the insulation of the enameled wire <NUM> is removed and the connection is maintained over time, said tab acting as a spring on the wire <NUM> and holding it taut.

According to an embodiment, the terminal <NUM> also has a pair of pocket engagement surfaces <NUM>, <NUM> oriented orthogonally to the terminal midplane M'-M' and suitable to ensure the correct positioning of the terminal <NUM> in the pocket <NUM>. In the present case, these pocket engagement surfaces <NUM>, <NUM> are suitable for contacting a pair of stop surfaces <NUM>, <NUM> formed on the pocket <NUM>. Specifically, this pair of stop surfaces <NUM>, <NUM> is connected to the pair of side guide walls <NUM>, <NUM> by means of the corresponding bevels <NUM>;<NUM>.

Preferably, the pin <NUM> has a polygonal-shaped cross section, for example a quadrangular cross section, where the side walls <NUM>, <NUM> are connected to each other by connecting walls <NUM>, <NUM>. The side wall <NUM> of said side walls <NUM>, <NUM> is counter-shaped with respect to the outer side <NUM> so as to ensure a uniform support for the wire <NUM>, which is coaxially wound around the pin <NUM>, during the insertion of the terminal <NUM>.

Due to the fact that the outer side <NUM> of the tab <NUM> is counter-shaped with respect to the side wall <NUM> of the pin <NUM>, and jointly with respect to the shape of the tab <NUM>, the enameled wire <NUM> is pressed against the pin <NUM> in a gradual, progressive and uniform manner. In this way, it is possible to abrade the enamel coating without cutting the wire, and thus an insulation displacement connection may be used even on enameled wires having small diameters.

<FIG> illustrate how the enameled wire is abraded and crushed at least partially by the tab, although cutting of the wire itself is avoided due to the particular geometric shape of the tab combined with the shape of the pin <NUM>.

In an embodiment, the pin <NUM> comprises an upper pin <NUM> which defines the start and/or end position of the winding of the wire <NUM>.

Preferably, the upper pin <NUM> is delimited by shaped walls suitable for locking the wire <NUM> during the winding so that the wire <NUM> does not unwind.

According to an embodiment, the upper pin <NUM> has a quadrangular shape with respect to a section plane which is perpendicular to the midplane M-M.

In an embodiment, the upper pin <NUM> has a reduced cross section than the one defined by the side walls <NUM>, <NUM>, and said reduced cross section of the upper pin <NUM> is such as to facilitate the work of the tab <NUM> during the insertion of the terminal <NUM> up to the operating position. The term "operating position" means the position of electrical contact between the wire <NUM> and the terminal <NUM>, that is to say, after the terminal has been inserted into the pocket, the wire enamel has been removed from the shaped surface, and the electrical connection has been made.

In accordance with an embodiment, the pin <NUM> is delimited at the bottom by a pair of support walls <NUM>, <NUM> which are configured as a support base for the enameled wire <NUM>. Said pair of support walls <NUM>, <NUM> provides a stop for the wire spirally wound around the pin <NUM> and prevents the enameled wire from laterally protruding from the pocket <NUM>.

Preferably, the connection terminal <NUM> is formed in one piece together with at least one second connection terminal (<FIG>) to form a connection terminal pair. In the connection terminal pair, one terminal is used as the input terminal and the second terminal is used as the output terminal.

Preferably, the pocket <NUM> is formed in one piece together with at least one second pocket (<FIG> and <FIG>) so as to form a pocket pair. In the pocket pair, one pocket is used to accommodate the input terminal and the second pocket is used to accommodate the output terminal.

However, the connection system may comprise a plurality of terminals and a corresponding plurality of pockets, wherein each terminal of the plurality of terminals is provided with a single tab and each pocket of the plurality of pockets has a single pin that peripherally delimits the pocket together with the back wall and the pair of side guide walls. In addition, the number and shape of the plurality of terminals and also the number and shape of the plurality of pockets may be customized in accordance with customer requirements.

In particular, the pocket <NUM> is delimited frontally by the pin <NUM> which comprises at its base the pair of support walls <NUM>, <NUM>. This pair of support walls is respectively connected to the pair of stop surfaces <NUM>, <NUM>. In an embodiment, the support walls <NUM>, <NUM> are coplanar to the stop surfaces <NUM>, <NUM>.

The assembly and operation of a connection system according to the invention will now be described.

The first operation is to wind the enameled wire <NUM> on the pin <NUM> of the pocket <NUM>; starting from the upper pin <NUM>, the enameled wire <NUM> is wound from top to bottom over the side walls <NUM> and <NUM> and connecting walls <NUM>, <NUM> as far as the pair of support walls <NUM>, <NUM>; the winding direction is irrelevant.

Then the winding of the enameled wire <NUM> begins. After the winding is completed, the enameled wire <NUM> will be wound on the pin <NUM> of the second pocket <NUM>, starting from the pair of support walls <NUM>, <NUM> from the bottom to the top and ending on the upper pin <NUM>.

The winding is now ready for connection to the terminal <NUM>, where the electrical connection between the enameled wire <NUM> of the winding and the terminal <NUM> will be made mechanically, and in particular to the shaped surface <NUM> of the tab inside the pocket <NUM>.

The terminal <NUM> is placed over the pocket <NUM>; then, the terminal <NUM> starts to enter the pocket <NUM> (<FIG>).

The bevels <NUM> and <NUM> help the terminal <NUM> enter the pocket <NUM>, while the pair of side guide walls <NUM>, <NUM> of the pocket <NUM> guide the terminal <NUM> to the operating position.

When the tab <NUM> of the terminal <NUM> meets the enameled wire <NUM> wound on the upper pin <NUM>, said tab starts to creep over the enameled wire <NUM> and remove the enamel; the reaction of the pin <NUM> and of the enameled wire <NUM> causes the tab to tend to approach the body <NUM> by pivoting on the connection portion <NUM>.

The tab <NUM> works like a spring, exerting a spring pressure on the enameled wire <NUM> against the pin <NUM>.

Advantageously, due to the shaped surface <NUM>, once the terminal <NUM> has arrived at the final operating position, the enameled wire <NUM> is etched with linear progression.

In fact, the enameled wire <NUM> is elastically stressed by the outer side <NUM> and supported by the pin <NUM>.

This prevents the terminal <NUM> from cutting the enameled wire <NUM>, and thus from interrupting the passage of current, and also provides a large contact area for the passage of said electric current with a realistic "gas-tight" seal.

Therefore, the pin <NUM> forms a column that has the dual function of providing the enameled wire <NUM> with a seat where it may be placed, keeping it taut, and then providing support for the wire <NUM> when the terminal <NUM> is inserted from above.

Advantageously, the wire <NUM> is not shear-stressed from top to bottom but in an oblique/sloping manner; the coils of the winding help the preceding coil, and the slope of the tab <NUM> also facilitates work on the wire <NUM> by creeping/sliding.

Moreover, the tab <NUM> is elastic and thus tends to expand/open, helped also by the pin <NUM>, which increases the response of the enameled wire <NUM>, which is wound over it, towards the terminal <NUM>.

The terminal <NUM>, even in its insertion phase, always encounters a different coil of enameled wire <NUM> wound on the pin <NUM>, and this in turn responds as with the previous coils of the enameled wire <NUM>.

In addition, due to the sloping shape of the tab <NUM>, the topmost coils are more stressed while those at the foot of the pin <NUM> are not even touched.

Due to the shaping of the tab <NUM>, the wire is stressed progressively. Depending on the different diameter of the wire, it is automatically restrained in abutment against the pin <NUM> by a winding/coiling machine, before being etched or abraded by the tab <NUM> during the insertion into the pocket <NUM>. In any case, the continuity of electrical contact between the wire <NUM> and the terminal <NUM> is ensured.

This ensures that, during the insertion of the terminal <NUM> on the enameled wire <NUM> and on the pin <NUM>, under no circumstances will the force of the tab <NUM> on the wire <NUM> and the continuity in the passage of current between the enameled wire <NUM> and terminal <NUM> be lost.

The constant force created by the terminal <NUM> on the wire/pin combination allows constant pressure to be maintained on the wire <NUM>.

The result is a "gas-tight" electrical connection between the terminal <NUM> and the wire <NUM> that is reliable and ensured under the vibrations and thermal expansion that the connection system <NUM> may experience during use and that cause the wire <NUM> to expand and contract.

Innovatively, the insulation displacement connection system fulfills the intended purpose.

Advantageously, the connection terminal comprises a single tab, rather than at least two tabs, and this allows for a significant reduction in overall dimensions, that is to say, a reduction in the wire size-to-product ratio.

According to an advantageous aspect, winding of the wire is easier because the pin delimits the pocket and thus it is easier to proceed with winding the wire. By contrast, in the prior art, the pin was placed inside the pocket, for example centrally.

According to an even further advantageous aspect, the connection system ensures a reliable "gas-tight" electrical connection over a large wire cross section (wire diameter/contact length ratio) without a reduction of the diameter of the enameled wire.

Advantageously, the connection system is applicable to a whole range of products where, due to the need for limited overall dimensions, there is not enough space to insert a terminal with two contact ends.

According to an advantageous aspect, the connection system also allows a cost saving, because the terminal provides a single tab and the pocket is not subject to strict dimensional tolerances.

According to yet a further advantageous aspect, the connection system, in contrast to the traditional IDC systems, does not cut the wire, but merely removes the enamel and allows a large contact area. In this way, the system offers better resistance to stress due to vibration and/or thermal shock, especially in the automotive technical field.

Claim 1:
An insulation displacement connection system (<NUM>), for example a connection system of the "IDC" type, comprising:
a) a connection terminal (<NUM>);
b) a pocket (<NUM>) suitable for accommodating said connection terminal (<NUM>);
c) an enameled wire (<NUM>) spirally wound and at least partly accommodated in said pocket (<NUM>),
wherein the pocket (<NUM>) comprises a pin (<NUM>) on which said wire (<NUM>) is wound,
and wherein:
- the pin (<NUM>) is delimited by side walls (<NUM>, <NUM>) which support the enameled wire during the winding of the wire (<NUM>) onto the pin (<NUM>), the pin (<NUM>) further comprising a midplane (M-M) and said midplane (M-M) preferably also being a plane of symmetry for the pocket (<NUM>),
characterized in that:
- the pocket (<NUM>) is frontally delimited by the pin (<NUM>), at the back by a rear wall (<NUM>) and laterally by a pair of side guide walls (<NUM>, <NUM>) suitable for guiding the connection terminal (<NUM>) during the insertion thereof into the pocket (<NUM>),
- the connection terminal (<NUM>) is provided with a single tab (<NUM>) shaped to elastically intercept the pin (<NUM>) so as to exert an abrasive action on the enameled wire (<NUM>) during the insertion of the connection terminal (<NUM>) into the pocket (<NUM>) and so as to elastically bias the wire (<NUM>) to abut against the pin (<NUM>) upon the insertion of said terminal (<NUM>) into the pocket (<NUM>), thus ensuring the electric connection between the single tab (<NUM>) and the wire (<NUM>),
- the single tab (<NUM>) comprises an outer side (<NUM>) suitable for intercepting the wire, said outer side (<NUM>) having a shaped surface (<NUM>) which directly interfaces with the enameled wire, said single tab (<NUM>) further comprising a terminal midplane (M'-M') suitable for being coplanar to the midplane (M-M),
- the pin (<NUM>), the rear wall (<NUM>) and the pair of side guide walls (<NUM>, <NUM>) delimit a cavity (<NUM>) for accommodating the connection terminal (<NUM>), in particular the tab (<NUM>).