EP0203009B1 - Electrically insulating support of blades for an electrical contact and manufacturing process - Google Patents

Description

The present invention relates to the manufacture of electrical devices of the type comprising a support made of electrically insulating material overmolded on at least one contact strip of electrically conductive material intended to be electrically connected with at least one electrical accessory.

In the following description, the expression "electrical accessory" should be understood in a broad sense, the expression "electrical accessory" having to cover any type of electrical device transmitting or receiving electrical information.

The present invention finds particular application in the production of measurement devices for motor vehicles.

By way of nonlimiting example, mention may be made of the production of electrically insulating caps supporting contact blades closing the housing of a temperature measurement device with bimetal warning contact.

In a large number of cases, the electrically conductive connecting part connected to the electrical accessory has a complex shape, imposed by the environment of the electrical accessory to be connected.

In the case, for example, of the temperature measurement device with the aforementioned alert contact, the geometry of these contact strips must take account of the dimensions and geometry of the internal chamber of the housing containing the bimetallic element, and also containing , most often, a heat-resistant element for temperature measurement.

The production of such supports made of electrically insulating material molded onto at least one contact strip of electrically conductive material, of complex geometry, has not been resolved with satisfaction so far.

The first possibility offered for the production of these devices, which consists in initially conforming, according to the required geometry, the contact strips, then later, in overmolding the insulating support on these strips, requires the production of molds taking account of the specific geometry. contact strips.

It follows on the one hand that these molds are expensive. Furthermore, the molds thus designed can only be used for the production of a particular type of device, the geometry of the contact strips varying widely from one application to another.

The second possibility offered for the production of these devices consists of overmolding the support of electrically insulating material on electrically conductive contact strips, initially rectilinear, then of conforming, after overmolding of the support, the contact strips according to the required geometry.

In practice, given the small dimensions of the electrically insulating supports generally used, in particular in motor vehicles, it turns out to be very difficult to conform, by folding, with precision, the contact strips after the molding of the insulating support.

For example, the difference between two adjacent contact strips can be of the order of a millimeter.

• - une embase intermédiaire de contact en matériau électriquement conducteur comportant une plaque munie d'une ouverture et, au niveau de celle-ci, d'au moins une lèvre élastique formant pince, pour permettre l'engagement de l'embase sur une extrémité de la lamelle de contact et le maintien sur celle-ci grâce à la lèvre élastique, et
• - une languette de contact en prise mécanique avec le support électriquement isolant et reposant contre l'embase intermédiaire, qui est reliée par ailleurs avec l'accessoire.

The present invention now improves the situation by proposing a new electrical device comprising a support of electrically insulating material overmolded on at least one contact strip of electrically conductive material, characterized in that it comprises, to ensure the electrical connection of contact strip with an electrical accessory-transmitter or receiver:

• - an intermediate contact base made of electrically conductive material comprising a plate provided with an opening and, at the level of this, at least one elastic lip forming a clamp, to allow engagement of the base on one end of the contact strip and the support thereon by means of the elastic lip, and
• - A contact tab in mechanical engagement with the electrically insulating support and resting against the intermediate base, which is also connected with the accessory.

In other words, according to the present invention, it is proposed to produce the connecting member carried by the electrically insulating support and in electrical contact with the accessory in the form of two separate elements, one corresponding to a contact strip. of standard shape on which the electrically insulating support is molded, the other to a contact tongue of required geometry, mechanically fixed on the electrically insulating support and electrically connected to the contact strip by the intermediate base.

Thus, according to the present invention, the molds used to ensure the overmolding of the electrically insulating support on the contact strips can be standard.

Likewise, the contact tabs being shaped separately, the geometry of these can be defined with precision.

It will also be noted that the electrically insulating support overmolded on at least one contact strip, in accordance with the present invention, constitutes a standard product capable, depending on the geometry of the contact tongues which will be associated with it later, of being used for a large number of applications.

Thus, the present invention makes it possible to obtain economic, reliable and precise electrical devices, making it possible, moreover, to resolve to a large extent the inventory problems hitherto posed.

Furthermore, the present invention justifies and authorizes, thanks to the standard shape of the parts used, and the simplicity of the system, automatic assembly.

Preferably, according to the invention, the mechanical immobilization of each contact tongue on the electrically insulating support is achieved by engagement of a protruding lug provided on the contact tongue in a complementary recess of the support.

More specifically, preferably, according to the present invention, each contact tab comprises two protruding lugs penetrating into respective complementary recesses formed in the support on either side of the electrical contact strip.

According to an embodiment currently considered preferential, each base has two converging elastic lips.

More precisely still, preferably, according to the invention, the lips are formed by cutting an "H" shaped opening in the base.

It is more advantageous that the two aforementioned lips have two parallel free edges intended to be applied on either side of the contact strip carried by the electrically insulating support.

Tests have shown that it was more advantageous to use a slightly concave base plate, the lip or lips being placed projecting on the plate opposite the concavity.

According to the invention, the contact strips preferably have a cross section of rectangular shape.

The present invention also relates to a method of manufacturing the above-mentioned electrical device.

• - la figure 1 représente une vue schématique, partiellement en coupe axiale longitudinale, d'un dispositif conforme à un exemple de réalisation de la présente invention,
• - la figure 2 représente une vue en bout d'un support électriquement isolant surmoulé sur des lamelles de contact, selon une vue illustrée par la flèche référencée Il sur la figure 4,
• - la figure 3 représente une vue partielle en coupe du même dispositif, selon un plan de coupe référencé III-III sur la figure 2,
• - la figure 4 représente une vue en coupe axiale longitudinale du même dispositif selon un plan de coupe référencé IV-IV sur la figure 2,
• - la figure 5 représente une vue latérale d'un exemple de réalisation de languettes de contact utilisées dans le cadre de la présente invention,
• - la figure 6 représente une vue de la même languette selon un plan de coupe longitudinal référencé VI-VI sur la figure 5,
• - la figure 7 représente une vue en plan d'une embase intermédiaire de contact conforme à la présente invention,
• - la figure 8 représente une vue en coupe de la même embase selon un plan de coupe référencé VIII-VIII sur la figure 7.

Other characteristics and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of nonlimiting examples and in which:

• FIG. 1 represents a schematic view, partially in longitudinal axial section, of a device according to an exemplary embodiment of the present invention,
• FIG. 2 represents an end view of an electrically insulating support overmolded on contact strips, according to a view illustrated by the arrow referenced II in FIG. 4,
• FIG. 3 represents a partial sectional view of the same device, according to a section plane referenced III-III in FIG. 2,
• FIG. 4 represents a view in longitudinal axial section of the same device according to a section plane referenced IV-IV in FIG. 2,
• FIG. 5 represents a side view of an exemplary embodiment of contact tabs used in the context of the present invention,
• FIG. 6 represents a view of the same tongue according to a longitudinal section plane referenced VI-VI in FIG. 5,
• FIG. 7 represents a plan view of an intermediate contact base in accordance with the present invention,
• FIG. 8 represents a sectional view of the same base according to a cutting plane referenced VIII-VIII in FIG. 7.

We see in Figures 1, 2 and 4, a support 10 of electrically insulating material overmolded on three contact strips 20, 21 and 22 of electrically conductive material.

By way of example, each of the contact strips is formed of a flat strip of rectangular cross section. At the level of the overmolding, each of the contact strips 20, 21 and 22 is provided with projections schematically referenced 23, preferably on its face of lesser width. The purpose of these projections 23 is to ensure effective mechanical retention of the contact strips 20, 21 and 22 in the overmolding 10.

Overmolding 10 is carried out so that the contact strips, generally parallel, emerge on either side of it.

Preferably, as shown in particular in FIG. 4, and illustrated under references 24 and 25, each contact strip 20, 21 and 22 is bevelled at its free ends, in order to facilitate on the one hand the engagement of an intermediate contact base 40, as shown in FIGS. 7 and 8, on the other hand the engagement of complementary electrical connection means.

Preferably, as mentioned above, the electrically insulating support 10 is intended to close a housing housing measurement means intended to be electrically connected to the contact strips 20, 21 and 22.

In this hypothesis, the face 11 of the electrically insulating support directed towards the internal chamber of the housing is preferably generally planar. On the other hand, on the opposite side, the electrically insulating support 10 preferably forms a skirt 12 surrounding at a distance the free end of the contact strips 20, 21 and 22, in order to protect them, and to receive the insulating housing d 'a complementary electrical connector intended to cooperate with the contact strips 20, 21 and 22 in a conventional manner per se.

It will be noted on examining FIG. 4 that, preferably, on its face 11 against which the intermediate contact bases 40 will later be affixed, the overmolded support 10 has a recess chamfer surrounding each of the contact strips 20, 21 and 22.

These chamfers make it possible in particular to avoid the presence of burrs of electrically insulating material, during molding, on the periphery of the contact strips 20, 21 and 22 to subsequently guarantee that the intermediate contact bases 40 can be brought into close contact with the side 11 of the insulating support 10.

Furthermore, on its surface 11 directed towards the side receiving the intermediate contact bases 40, the insulating support 10 has a plurality of recesses 13 intended to ensure the mechanical immobilization of the contact tongues.

Preferably, two recesses are thus placed on either side of the contact strips 40.

We thus see in Figure 2 two pairs of blind recesses 13 of general rectangular cross section.

Where appropriate, as illustrated in FIGS. 2 and 3, the face 11 of the support 0 may also have a projection 14 forming a polarizing device.

As illustrated in FIGS. 7 and 8, each intermediate contact base 40 is formed of a plate provided with an opening 41 delimiting at the level of the latter at least one elastic lip 42, 43 allowing the engagement of the base 40 on the end 27 of the contact strips and the holding of the base thereon by elastic clamping.

As illustrated in FIG. 7, according to an embodiment currently considered preferential, an H-shaped opening 41 is made in the base 40 to delimit two lips 42, 43 of generally rectangular outline, converging, forming elastic clamp.

Preferably, as illustrated in FIG. 8, the lips 42 and 43 are deformed projecting from the same side of the base 40.

Preferably, the free edges 44, 45 of the lips 42 and 43, arranged opposite, are parallel.

In use, the lips 42 and 43 will rest at the level of these free edges 44 and 45 against the respectively opposite sides of the contact strips 20, 22 carried by the support 10.

The distance separating the free edges 44 and 45 of the elastic lips 42, 43 must of course be less than the width of the contact strips 20, 21, 22 supported by the base 10, in order to ensure effective support of the bases 40 on the contact strips.

Preferably, as it appears on examining FIG. 8, the body 46 of the base 40 is slightly concave and the elastic lip (s) 42, 43 are arranged projecting from the 'base opposite the concavity.

Where appropriate, as appears on examining FIGS. 7 and 8, two tabs 47, 48 intended to rest in use against the face 11 of the electrically insulating support 10 are provided on either side of the body 46 of the base.

Such bases 40 can be produced from flat metal blanks by virtue of conventional stamping and folding operations in themselves.

FIGS. 5 and 6 illustrate an embodiment of the contact tongues 30 intended to ensure the electrical connection of a contact strip with an associated electrical accessory.

Essentially, these contact tabs 30 comprise a body 31 intended to be electrically connected to the electrical accessory, and shaped according to the geometry and dimensions required by the environment thereof, as well as means 32 intended for come into mechanical engagement with the electrically insulating support and rest against an intermediate base engaged on a contact strip.

In this case, according to the illustration shown in FIGS. 5 and 6, the means 32 comprise a bridge 33 extending transversely to the direction of elongation of the body 31 and provided opposite the latter with two lugs 34, 35 generally parallel intended respectively to penetrate into complementary recesses 13 formed in the electrically insulating support 10.

Furthermore, as appears on examining FIG. 5 and as illustrated schematically by the reference 36, the free end of the studs 34, 35 by which these are engaged in the recesses 13 is preferably bevelled so to facilitate such engagement.

It will also be noted on examining FIG. 5 that the pins 34, 35 are preferably slightly tapered over their width, in the direction of the aforementioned free ends and have transverse support surfaces schematically illustrated 37, directed towards the body 31 , that is to say to use towards the opening of the recesses 13 in order to prohibit the withdrawal of the contact tabs 30 from the recesses 13.

As illustrated in FIG. 5, the trigger guard 33 can have a central recess 38 open in the direction of the lugs 34, 35 to allow the contact tongue 30 to overlap the contact strips 20 as illustrated at the top of FIG. 1.

The trigger guard 33 preferably has a flat support surface 39 perpendicular to the direction of elongation of the body 31 and of the lugs 34, 35, intended for use to rest against the base 40, and preferably against the lips. elastic 42 and 43.

• - à supporter au moins une lamelle de contact dans un moule,
• - à surmouler le support électriquement isolant 10 sur la lamelle de contact, de telle sorte que celle-ci émerge de part et d'autre du surmoulage isolant, et en réalisant des moyens de fixation mécaniques pour les languettes, sur le surmoulage isolant 10,
• - à engager une embase intermédiaire de contact 40 sur les lamelles, au niveau de leur ouverture 41, les embases intermédiaires de contact 40 étant maintenues sur les lamelles de contact grâce aux lèvres élastiques,
• - à engager enfin les ergots 34, 35 des languettes de contact 30 dans les évidements 13 complémentaires du support isolant 10 jusqu'à obtention d'une liaison mécanique entre le support électriquement isolant 10 et les languettes 30 et d'un appui de la surface 39 des languettes contre l'embase intermédiaire des contacts 40.

The method for manufacturing the aforementioned device comprises the steps consisting:

• - to support at least one contact strip in a mold,
• - overmolding the electrically insulating support 10 on the contact strip, so that the latter emerges on either side of the insulating overmolding, and by making mechanical fixing means for the tongues, on the insulating overmolding 10,
• - engaging an intermediate contact base 40 on the lamellae, at their opening 41, the intermediate contact base 40 being held on the contact lamellae by means of the elastic lips,
• - Finally, engaging the pins 34, 35 of the contact tabs 30 in the complementary recesses 13 of the insulating support 10 until a mechanical connection is obtained between the electrically insulating support 10 and the tabs 30 and a support of the surface 39 of the tabs against the intermediate base of the contacts 40.

After these operations have been carried out, the contact strips 30 are held firmly on the overmolded insulating support 10 on the one hand, and the contact tabs 30 are reliably electrically connected to the contact strips 20, 21 and 22 via the bases 40, on the other hand.

As shown in Figure 1, if necessary, some of the bases 40 can be used to directly provide the electrical connection with the accessory.

To do this, preferably, the bases 40 in question are provided with a curved elastic wing 49 intended to come into contact directly or indirectly with the electrical accessory.

Of course, the present invention is in no way limited to the embodiment which has just been described but extends to any variant in accordance with its spirit.

According to an embodiment in accordance with the present invention, given by way of nonlimiting example, the contact strips have a thickness of 0.9 mm and a width of the order of 2.5 mm, while the base 40 is produced in a copper alloy plate with a thickness of the order of 0.15 mm, having two lips with a width (corresponding to the length of the free edges 44, 45) of the order of 1, 4 mm, of a height (considered transversely to the free edges) of the order of 0.6 mm, the radius of curvature of the concave body of the base being of the order of 6 mm, the free edge of the lips 42, 43 being projecting of the order 0.2 mm above the convex concave body.

For example, the present invention also makes it possible to use lamellas of non-rectangular section, for example circular.

In addition, the bases may include more than two elastic lips, three for example or more, in particular with lamellae of circular section.

Claims (11)

1. An electric device of the type comprising a support (10) of electrically insulating material moulded on at least one contact blade (20, 21, 22) of an electrically conductive material, characterized in that it comprises, to ensure the electric connection of the contact blade with an electric transmitting or receiving accessory:

- an intermediate contact base (40) of an electrically conductive material comprising a plate (46) provided with an opening (41) and, at the level thereof, at least one resilient lip (42, 43) forming a clip, to enable the base (40) to be engaged on one end of the contact blade (20, 21, 22) and be retained thereon by the resilient lip, and

- a contact tongue (30) mechanically engaging (13; 34, 35) with the electrically insulating support (10) and resting against the intermediate base (40), which is connected to the accessory.

2. An electric device according to Claim 1, characterized in that each contact tongue (30) comprises at least one projecting pin (34, 35) extending into a complementary recess (13) provided in the support (10).

3. An electric device according to one of Claims 1 or 2, characterized in that each contact tongue (30) comprises two pins (34, 35) extending into complementary recesses provided in the electrically insulating support (10) on either side of an electric contact blade.

4. An electric device according to one of Claims 1 to 3, characterized in that each base (40) has two convergent resilient lips (42, 43).

5. An electric device according to Claim 4, characterized in that the lips (42, 43) are formed by cutting out an opening in the form of an H (41) in the base.

6. An electrical device according to one of Claims 4 or 5, characterized in that the two lips (42, 43) have two parallel free edges (44, 45).

7. An electric device according to one of Claims 1 to 6, characterized in that the plate (46) of the base (40) is slightly concave and the or each lip (42, 43) is disposed projecting opposite to the concavity.

8. An electric device according to one of Claims 1 to 7, characterized in that at least some of the blades (20, 21, 22) have a generally rectangular cross-section.

9. An electric device according to one of Claims 1 to 8, characterized in that at least some of the blades (20) have a generally circular cross-section.

10. A method of manufacturing an electric device according to one of Claims 1 to 9, characterized in that it comprises the steps of:

- moulding a support (10) of electrically insulating material on at least one contact blade (20) of electrically conductive material so that the blade emerges on either side of the insulating support (10),

- engaging an intermediate contact base (40) of electrically conductive material comprising a plate provided with an opening, and at the level thereof, a resilient lip forming a clip, on one end of a contact blade, the base (40) being retained on the contact blade by the resilient lip,
mechanically attaching a contact tongue (30) to the electrically insulating support (10) by causing a portion of the contact tongue (30) to bear against the intermediate contact base (40).

11. A method according to Claim 10, characterized in that a contact tongue (30) is mechanically immobilized on the electrically insulating support (10) by engaging preferably tapered pins (34, 35), with which the tongue (30) is formed, in complementary recesses (13) in the insulating support (10).

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