FR3017025A1 - ANTI-SHORT CIRCUIT PROTECTION DEVICE FOR AN ELECTRIC VEHICLE EQUIPMENT. - Google Patents

Abstract

The present invention relates to a short-circuit protection device for an electrical equipment (1) of a motor vehicle comprising at least one electrical terminal (2A, 2B) intended to be connected to an end lug (3A, 3B) of a power cable, said device comprising a cover (20) comprising a main protective wall (21) designed to cover at least the projecting end of a said electrical terminal (2A, 2B) and a corresponding terminal (3A, 3B), said cover (20) being made of an electrically insulating material so as to avoid any electrical contact between said electrical equipment (1) and a conductive element connected to ground following a violent impact; characterized in that said cover (20) is obtained by molding from an expanded thermoplastic elastomer.

Description

ANTI-SHORT CIRCUIT PROTECTION DEVICE FOR AN ELECTRIC VEHICLE EQUIPMENT. FIELD OF THE INVENTION The present invention relates generally to the field of electrical equipment comprising at least one electrical terminal intended to be coupled to a terminal of a power cable connected to the battery of a motor vehicle. The invention aims in particular a short circuit protection device for such electrical equipment in case of violent impact due for example to a frontal collision. BACKGROUND OF THE INVENTION In order to reduce the risk of a short circuit in the event of a violent shock resulting in a crushing of the motor unit, the power cables connecting the electrical equipment to the battery are generally covered with an insulating protective sheath. Aramide capable of suffering such a shock without breaking or piercing. This type of sheath, however, does not allow to isolate the entire circuit since the connection terminals of these electrical equipment and the end lugs of the power cables coming to connect remain exposed. In fact, during an impact, one of the connection terminals and / or end lugs connected thereto may come into contact with a conductive element connected to ground and generate a short circuit causing a malfunction. of the electrical equipment in question (which is particularly problematic when this equipment provides safe functions) and / or the occurrence of sparks that can trigger a fire. In order to reduce the risks involved, the power cables are generally associated with a safety fuse and / or arranged behind the battery so that the delivered current is weakened (by crushing the latter during the shock) before the appearance of the short circuit.

These solutions are unfortunately ineffective for vehicles equipped with electrical equipment whose housings are arranged at the front of the battery and require a non-fuse current supply.

In order to ensure the protection of this type of electrical equipment in the event of a violent impact, and to avoid any electrical contact between such electronic equipment and a conductive element connected to ground, the French patent application FR 2 990 068 discloses a protective device comprising a cover comprising a protective wall placed in front of the electrical terminal and the associated lug and made of a material both rigid and electrically insulating such as epoxy or a plastic and fiber composite material. The front face of this protective wall is further covered by a damping material such as a synthetic rubber, so as to reduce the force taken by this rigid material and thus prevent the hood can break under the violence of the shock . Unfortunately, in case of particularly violent shock, the damping provided by this layer of damping material is not necessarily sufficient to prevent the rigid protection zone is pierced by a protruding terminal of the electrical equipment. In addition, this type of bi-material device has a high cost. OBJECT AND SUMMARY OF THE INVENTION The present invention therefore aims to propose a solution that is both simple and inexpensive to avoid, during a violent impact, that one of the connection terminals of such electrical equipment and / or or end lugs connected to it may come into contact with a conductive element connected to ground and thereby generate a short circuit. It proposes for this purpose a short-circuit protection device for a motor vehicle electrical equipment comprising at least one electrical terminal intended to be connected to an end lug of a power cable, said device comprising a cover comprising a main protective wall designed to cover at least the projecting end of a said electrical terminal and a corresponding said lug, said cover being made of an electrically insulating material so as to avoid any electrical contact between said electrical equipment and a conductive element connected to ground following a violent impact; characterized in that said hood is obtained by molding from an expanded thermoplastic elastomer. The fact that the cover of the protective device according to the invention is made entirely of an elastomeric material prevents the latter from being pierced by the projecting end of an electrical terminal and breaks, even in the event of a particularly violent shock. generating a very significant compression force on the hood as is particularly the case in a frontal collision where the compressive force exerted on its main wall can reach several kN. In addition, the cells constituting the expanded structure of this material can stop the propagation of any micro-cracks that may appear in the material during such a shock, so as to preserve excellent electrical insulation of the equipment . According to preferred features of the protective device according to the invention, taken alone or in combination: said expanded thermoplastic elastomer is chosen from the group of ethylene-propylene-diene monomer-polypropylene type polymers, ethylene-propylene-type polymers; diene monomer and polymers of polystyrene-b-poly (ethylenebutylene) -b-polystyrene type; said cover has a substantially constant thickness and between 2 and 6 mm; said protective device comprises a metal insert integral with said cover and having a hole intended to be threaded onto a threaded stud of said electrical equipment in order to allow said protection device to be fixed on said electrical equipment by means of a cooperating screwing nut; with said stud; - said cover has an inner side, at least one housing for housing a projecting end of a said electrical terminal and a fastener for securing said corresponding lug to said projecting end; said threaded stud forms a so-called electrical terminal while said tightening nut forms a said fixing member, said main protective wall having an opening extending on the inner side by a wall, a portion of which of said insert in which said hole is formed overlaps the distal end, said protection device further comprising a plug having a shape complementary to that of said opening and intended to close it after the introduction of said protective device on said electrical equipment, so as to form with said wall; a said housing for the protruding end of said threaded stud and for said nut; said cover comprises a lateral wall extending perpendicularly to said main protective wall from at least part of its periphery and intended to surround at least the projecting end of said electrical terminal and said corresponding terminal; said lateral wall comprises latching means capable of cooperating with complementary means situated on said electrical equipment; and / or - said side wall has an orifice shaped to allow the introduction of a said power cable by its end lug before it is connected to a said electrical terminal. The invention also aims in a second aspect, a motor vehicle having an electrical equipment comprising at least one electrical terminal intended to be connected to an end lug of a power cable; characterized in that it further comprises such a protective device mounted on said electrical equipment.

Brief description of the drawings The description of the invention will now be continued by the detailed description of an exemplary embodiment, given below by way of illustration but without limitation, with reference to the appended drawings, in which: FIG. a perspective view of three quarters before a protection device according to a first embodiment of the invention; - Figure 2 shows a rear view of the protective device of Figure 1; - Figure 3 is a sectional view of the protective device of Figure 1 in its mounted configuration taken along the plane III-III of Figure 2; FIG. 4 represents a perspective view of three quarters front of a protection device according to a second embodiment of the invention; - Figure 5 shows a rear view of the protective device of Figure 4; FIG. 6 is a perspective view of the metal insert included in the protective device of FIG. 4; and FIG. 7 is a sectional view of the protective device of FIG. 4 in its assembled configuration, taken along the plane VII-VII of FIG. 5. DETAILED DESCRIPTION OF TWO EMBODIMENTS OF THE INVENTION FIGS. 3 show a protection device 10 according to a first embodiment of the invention.

This device 10 is intended to protect electrical equipment 1 constituted in this case by a computer-type computer unit located at the front of the engine compartment of a motor vehicle and visible in Figure 3.

This electronic box 1 comprises on its front face, two electrical terminals 2A, 2B each coupled to a corresponding lug 3A, 3B located at a first end of a respective power cable whose other end (not shown in the drawings) is respectively connected to the battery and to a functional organ of this vehicle such as a starter. As illustrated in Figure 3, each of the electrical terminals is formed by a metal stud 2A, 2B threaded on which is threaded the eyelet of a terminal 3A, 3B. A fixing nut 5A, 5B is screwed onto each bolt 2A, 2B in order to secure this lug 3A, 3B. The protective device 10 intended here to be disposed in a generally vertical plane situated at the front of the electronic box 1, is constituted by a cover 20 made of an electrically insulating material so as to avoid any electrical contact between this electronic box 1 and a conductive element connected to ground following a violent impact such as a frontal collision. The cover 20 comprises a main protective wall 21 intended to cover the two studs 2A, 2B and the two lugs 3A, 3B associated therewith, as well as a side wall 26 extending perpendicular to the protective wall 21 from at least a portion of its periphery and intended to surround the same studs 2A, 2B and lugs 3A, 3B. As illustrated in FIG. 2, the main wall 21 has, on the inside, two cylindrical housings 22A, 22B each intended to house a protruding end of a respective stud 2A, 2B of the electronic box 1 as well as the nut 5A, 5B which there is screwed. This main wall 21 also has internal side, support ribs 23 provided to bear against the lugs 3A, 3B and against the electronic housing 1 in the vicinity of the studs 2A, 2B (Figure 3). In order to maintain the cover 20 on the electronic housing 1, its peripheral lateral wall 26 comprises fastening means constituted here by ratchet teeth 27 adapted to cooperate with complementary detents or notches located on this electronic housing 1 It will be noted that two of these latching teeth 27 are disposed at two pre-cut lugs 28 in the peripheral side wall 26. The presence of these elastically deformable lugs 28 makes it possible, if necessary, to facilitate the removal of the hood 20. The Hood 20 has come integrally molded from an expanded thermoplastic elastomer, preferably selected from the group of EPDM-PP polymers, EPDM polymers and SEBS polymers. The fact that the cover is made entirely of an elastomeric material prevents the latter from being pierced by the projecting end of a stud 2A, 2B and breaks, even in the event of a particularly violent shock generating a very high compression force. important on this hood (this is particularly the case in a frontal collision where the compressive force exerted on the main wall 21 of the hood can reach several kN). In addition, the cells constituting the expanded structure of this material make it possible to stop the propagation of any micro-cracks that may appear in the material during such an impact, so as to preserve excellent electrical insulation of the electronic unit 1 The thickness of the cover 20 is between 2 and 6 mm, and preferably between 4 and 5 mm, which makes it possible to obtain a high level of protection while satisfying the implantation constraints (particularly limited space available between the elements housed in the engine block). This thickness is also substantially constant over the entire cover 20, which provides a better manufacturing quality by ensuring a homogeneous spread of the material in the mold. We will now describe a second embodiment of the protective device according to the invention in support of Figures 4 to 7.

In the following and in the drawings, the elements similar to the first embodiment retain the same references but are decorated with a premium. The protective device 10 'is also intended to protect an electrical equipment 1' constituted here by a computer-type electronic box located at the front of the engine compartment of a motor vehicle and visible in FIG. 7. This electronic box 1 ' has on its upper face, two electrical terminals 2A ', 2B' each coupled to a corresponding lug 3A ', 3B' located at a first end of a power cable 4A ', 4B' whose other end (not shown in the drawings) is respectively connected to the battery and to a functional member of this vehicle such as a starter. As illustrated in FIG. 7, each of the electrical terminals is formed by a threaded metal stud 2A ', 2B' on which is threaded the eyelet of a lug 3A ', 3B'. A fixing nut 5A ', 5B' is screwed onto each bolt 2A ', 2B' in order to secure this lug 3A ', 3B'. The protective device 10 'intended here to be disposed above the electronic box 1' in a substantially horizontal plane, comprises a cover 20 'and a metal attachment insert 30' integrated in this cover 20 '. Like the cover 20 described above, the cover 20 'is made of an electrically insulating material so as to avoid any electrical contact between this electronic box 1' and a conductive element connected to ground following a violent shock such as a collision end. This cover 20 'comprises a main protective wall 21' intended to cover the two studs 2A ', 2B' and the two lugs 3A ', 3B' associated therewith, and a side wall 26 'extending perpendicularly to the protective wall 21 'from at least a portion of its periphery and intended to surround these studs 2A', 2B 'and lugs 3A', 3B '. As illustrated in FIG. 5, the main wall 21 'has an internal side, a first cylindrical housing 22' intended to house the projecting end of a first stud 2A 'of the electronic box 1' and the nut 5A 'which is screwed. This main wall 21 'also has internal side, support ribs 23' provided to bear against the lugs 3 'and against the electronic housing 1' in the vicinity of the studs 2 '(Figure 7). A circular opening 24a 'is further provided in the main wall 21' (Figure 4), the latter extending from the inner side by a cylindrical wall 24b '(Figure 5).

The cover 20 'further comprises a plug 24c' having a shape complementary to that of the opening 24a ', the latter being connected to the main wall 21' via a connecting tongue 25 '(FIGS. 5). This plug 24c 'intended to close the opening 24a' after the introduction of the protective device 1 ', so as to form with the wall 24b' a second cylindrical housing 24 'for housing the projecting end of the second stud 2B 'and the nut 5B' which is screwed to it (Figure 7). The peripheral side wall 26 'of the cover 20' has ratchet teeth 27 'adapted to cooperate with complementary notches or lugs located on this electronic unit 1 to ensure a first partial maintenance of the cover 20 on the electronic unit 1'. This peripheral side wall 26 'also has an orifice 29' located near the first housing 22 'and shaped to allow the introduction of the first power cable 4A' through its end lug 3A 'before it is connected to the first stud 2A 'with the screw nut 5A' (Figure 7). Due to the presence of this passage hole 29 'crossed by the supply cable 4A', the latter ensures the retention of the area of the cover 20 'covering the first pin 2A' and the associated lug 3A 'and avoids that the latter can not lift, even in case of particularly violent shock generating a very large pulling force on the hood (this is particularly the case in a frontal collision where the pulling force exerted on the side wall device 26 'of the hood 20' can reach several kN).

As well as the cover 20, the cover 20 'is obtained by molding from an expanded thermoplastic elastomer, preferably selected from the group of ethylene-propylene-diene monomer-polypropylene polymers (also called EPDM-PP), ethylene-propylene-diene monomer polymers (also called EPDM) and polystyrene-b-poly (ethylene-butylene) -b-polystyrene polymers (also called SEBS). The thickness of the cover 20 'is also substantially constant and between 2 and 6 mm. This thickness is preferably between 2.5 and 3 mm, the compressive forces experienced by this cover 20 'in the event of a violent impact being less because of its horizontally mounted configuration. The metal insert 30 'shown alone in Figure 6 is formed of a cut and folded metal sheet, optionally covered with a conductive coating for protecting the sheet against oxidation induced by the flow of electric current. This insert 30 'has a sole 31' having a circular hole 32 ', and two lugs 33' extending perpendicularly to the sole 31 'and in each of which is formed a window 34'. The insert 30 'is placed in the bonnet mold 20' before the injection of the thermoplastic elastomer. The tabs 33 'are intended to be trapped in the material after molding, so as to make integral the insert 30' and the cover 20 '. This bonding is further enhanced by the presence of the windows 34 'made in the legs 33' and which are traversed by the liquid material during the injection phase. As illustrated in FIG. 5, the sole 31 'of the insert 30' covers the distal end of the cylindrical wall 24B extending the opening 24 ', so that the circular hole 32' is centered on the axis of this cylindrical wall 24b '. The sole 31 'of the insert 30' is intended to be threaded via the hole 32 'on the second pin 2B' above the lug 3B 'and before the tightening of the fixing nut 5B'.

The presence of this metal insert 30 'ensures reliable attachment of the protection device 10' at the area of the cover 20 'covering the second stud 2B' and the associated lug 3B ', and avoids that the latter can not to lift, even in case of particularly violent shock generating a very large tearing force on the cover 20 '. We will now briefly describe the implementation of the protective device 20 'on the electrical box 1'. The first step is to introduce the end lug 3A 'of the power cable 4A' through the passage opening 29 'of the protective device 10', and to slide the latter along a portion of this cable 4A 'so as to freely access the lug 3A'. The eyelet of this lug 3A 'must then be threaded onto the first stud 2A' and then fixed thereto by screwing the fixing nut 5A ', while the eyelet of the second lug 3B' must simply be threaded on the second stud 2B '. The protection device 10 'can now be returned towards the control unit 1', so as to allow it to be put in place and to be threaded on the sole 31 'via the hole 32' on the second stud 2B 'above the second pod 3B '. The fastening nut 5B 'is then screwed onto this bolt 2B' so as to simultaneously secure the lug 3B 'and the protection device 10'.

There is then only to arrange the plug force in the opening 24 'of the main wall 21' of the cover 20 '. The protection device 10 'now occupies its mounted configuration illustrated in FIG. 7. According to non-illustrated alternative embodiments of the embodiments described, the protection device is intended to protect only one terminal of the electrical equipment ( that connected to the battery) and therefore includes only a single housing to receive it.

Of course, the present invention is not limited to the embodiments described and shown, but it encompasses any embodiment within the reach of the skilled person.

Claims (10)

REVENDICATIONS1. Short circuit protection device for an electrical equipment (1; 1 ') of a motor vehicle comprising at least one electrical terminal (2A, 2B; 2A', 2B ') intended to be connected to an end terminal (3A, 3B; 3A ', 3B') of a power cable (4A ', 4B'), said device comprising a cover (20; 20 ') comprising a main protective wall (21; 21') provided for covering at the minus the protruding end of a said electrical terminal (2A, 2B; 2A ', 2B') and a said corresponding terminal (3A, 3B; 3A ', 3B'), said cover (20; 20 ') being made of an electrically insulating material so as to avoid any electrical contact between said electrical equipment (1; 1 ') and a conductive element connected to the ground as a result of a violent impact; characterized in that said cover (20; 20 ') is obtained by molding from an expanded thermoplastic elastomer. 2. Protective device according to claim 1, characterized in that said expanded thermoplastic elastomer is selected from the group of ethylene-propylene-diene monomer-polypropylene polymers, ethylene-propylene-diene monomer type polymers and polymers of type polystyrene-b-poly (ethylenebutylene) -b-polystyrene. 3. Protective device according to one of claims 1 or 2, characterized in that said cover (20; 20 ') has a substantially constant thickness and between 2 and 6 mm. 4. Protective device according to one of claims 1 to 3, characterized in that it comprises a metal insert (30 ') integral with said cover (20') and having a hole (32 ') intended to be threaded on a threaded stud (2B ') of said electrical equipment (1') for enabling said protection device to be fixed to said electrical equipment (1 ') by means of a screw nut (5B') cooperating with said stud (2B ') ). 5. Protective device according to one of claims 1 to 4, characterized in that said cover (20; 20 ') has an inner side, at least one housing (22A, 22B; 22', 24 ') intended to house one end protruding from a said electrical terminal (2A, 2B; 2A ', 2B') and a fixing member (5A, 5B; 5A ', 5B') ensuring the securing of said corresponding lug (3A, 3B; 3A ' , 3B ') at said projecting end. 6. Protection device according to claims 4 and 5, characterized in that said threaded stud (2B ') forms a said electrical terminal while said screw nut (5B') forms a said fixing member, said main wall protection device (21 ') having an opening (24a') extending on the inner side by a wall (24b '), a portion of which said insert (30') in which is formed said hole (32 ') covers the distal end, said protection device further comprising a plug (24c ') having a shape complementary to that of said opening (24a') and intended to close it after the introduction of said protection device on said electrical equipment (1 '), so as to form with said wall (24b ') a said housing (24') for the protruding end of said threaded stud (2B ') and for said nut (5B'). 7. Protective device according to one of claims 1 to 6, characterized in that said cover (20; 20 ') has a side wall (26; 26') extending perpendicularly to said main protective wall ( 21; 21 ') from at least a part of its periphery and intended to surround at least the projecting end of a said electrical terminal (2A, 2B; 2A', 2B ') and a corresponding said terminal (3A, 3B; 3A ', 3B'). 8. Protection device according to claim 7, characterized in that said side wall (26; 26 ') comprises latching means (27; 27') adapted to cooperate with complementary means located on said electrical equipment (1; 1 '). 9. Protective device according to one of claims 7 or 8, characterized in that said side wall (26 ') has an orifice (29') shaped to allow the introduction of a said power cable (4A '). ) by its end terminal (3A ') before it is connected to a said electrical terminal (2A'). 10. Motor vehicle comprising electrical equipment (1; 1 ') comprising at least one electrical terminal (2A, 2B; 2A', 2B ') intended to be connected to an end lug (3A, 3B; 3A', 3B ') a power cable (4A', 4B '); characterized in that it further comprises a protection device (10; 10 ') according to one of claims 1 to 9, mounted on said electrical equipment (1; 1').