WO2019053345A1

WO2019053345A1 - Structure for securing a motor vehicle busbar

Info

Publication number: WO2019053345A1
Application number: PCT/FR2018/051953
Authority: WO
Inventors: Sylvie ROULLAIS; Antoine ANDRE
Original assignee: Psa Automobiles Sa
Priority date: 2017-09-13
Filing date: 2018-07-30
Publication date: 2019-03-21
Also published as: MA50228A; FR3071108A1; CN111095606A; EP3682491A1; FR3071108B1

Abstract

This system for securing a motor vehicle busbar comprises a busbar (1), an electrically insulating cap (4) for protecting the busbar (1), at least partially covering said bar(1) and at least one fixing screw (5), comprising a body (6) and a screw (5) head (7), for joining together said bar (1) and said protective cap (4), the busbar (1) and the protective cap (4) having an orifice for the passage respectively of the screw (5) body (6) and of the screw (5) head (7), the width of the orifice in the protective cap (4) being at most equal to the diameter of the screw (5) head (7). The invention also relates to a motor vehicle comprising this busbar fixing system.

Description

SYSTEM FOR FASTENING A VEHICLE OMNIBUS BAR

AUTOMOBILE

The invention relates to a fastening system of a motor vehicle bus bar. More particularly, the invention intends to propose a solution for fixing but also to protect and electrically isolate a particular type of motor vehicle electrical cable which carries a high voltage (> 450 Volts), hence specific risks, these electric cables being known. at present under the name of bus bar or bus bar.

An electric vehicle such as an electric car or a hybrid car comprises a battery pack comprising a plurality of battery cells. The battery pack therefore comprises a plurality of battery cells in which the positive and negative electrodes are arranged adjacent each other, and the positive and negative electrodes of two adjacent battery cells are coupled to each other. other via a bus bar. Thus, a battery pack is constituted by the connection in series of all the battery cells, so that a high output voltage can be delivered (> 450 volts).

A bus bar for battery pack is conventionally in the form of a rigid bar which is formed by a conductor, for example copper, coated with insulation over its entire length. A bus bar has at its two ends a pair of two orifices in which the electrodes, negative and positive, of two batteries are introduced. The bus bars are optimally positioned in the battery environment (narrow areas, winding passages, etc.).

In a battery pack, a plurality of bus bars are often held together by a non-conductive support. The carrier has a plurality of insulating protective covers which are each attached to the end of a bus bar. Such a protective cover conventionally prevents any physical contact of a portion (its ends) of the bus bar. Thus, EP 1872421 is known which describes a housing or connection support for bus bars, or bus bar, comprising an insulating protective cover. Also known is patent EP 2688122 which describes a wiring module comprising bus bars or bus bars, comprising insulating elements having one or both of the connection holes having an oblong shape.

The protective covers must also carry fixing screws able to maintain and secure a close connection between the battery electrodes and the bus bar. These fixing screws must imperatively remain in position once screwed, first to ensure a good electrical connection between the electrodes and the bus bar but also to avoid creating short circuits by contacting other conductive elements, thus deteriorating irreparably battery pack, including creating arcs.

But, such fastening screws are subjected to many and intense mechanical stress during the cycle of transport and handling of the bus bars so that there is a risk that they are lost before mounting on a vehicle.

The present invention intends to propose a simple and economical solution for securing definitively the position of these fastening screws once these last screwed, ensuring on the one hand the fixing of the bus bar to the electrodes and on the other hand the anchoring of a protective cover at the busbar.

For this purpose, the present invention proposes a system for fixing a bus bar of a motor vehicle, comprising a bus bar, an electrically insulating protective cover of the bus bar at least partially covering said bar and at least one screw of fixing, comprising a body and a screw head, for fixing between said bar and a power supply, the bus bar and the protective cover having an orifice for the passage respectively of the screw body and the screw head , characterized in that the width of the orifice of the protective cover is at most equal to the diameter of the screw head. Thanks to the invention, once the fastening screw in its screwing position, it is constrained by clamping and friction by the protective cover, at its screw head in contact with the walls of the cover opening. protection, so that it can no longer move during the entire period of use of the vehicle (the battery pack or the bus bar), whatever the driving conditions of the motor vehicle.

Thus, on the one hand the busbar-electrodes fixation is ensured and on the other hand the intimate contact of the cover and the screw heads ensure the fixing of the screws and that of the protective cover on the end of the bus bar.

An advantage of the present invention is that it does not use any additional parts so that this solution is both economical and simple (without adding weight to the vehicle).

Another advantage lies in the fact that the hood also makes it possible not to lose the fastening screw in case of unwanted unscrewing during the use of the vehicle.

Preferably, the width of the orifice of the protective cover is less than the diameter of the screw head by at most one millimeter.

Preferably, the width of the orifice of the protective cover is at least 0.1 mm smaller than the diameter of the screw head.

Advantageously, the orifice of the protective cover has a section of oblong shape, the length of the orifice being greater than its width.

The protective covers of the state of the art currently require double tooling because the orifices (for the passage of the fixing screw heads) are not arranged symmetrically at the ends of a bar omnibus. Indeed, these orifices are off-center sometimes right and sometimes left on the busbar (see references 1 1 and 12 in Figure 3 attached which shows such a bus bar).

Thus, by providing orifices of oblong shape, it is no longer necessary to use as many tools because the protective covers adapt to one or the other end of a bus bar, whatever the arrangement of the orifices on the latter. For example, if we consider thirty bus bars, this is, with the prior art, nearly sixty tools (one per side), while with the solution according to the invention, only six tools are necessary.

This advantageous characteristic of the invention therefore makes it possible to reduce the diversity of tooling parts used and thus to reduce tooling costs. In addition, this solution saves time during assembly.

More specifically, preferably, the length of the opening of the protective cover is at least equal to 1.5 times its width.

According to a preferred embodiment of the invention, the protective cover is made of plastic.

Advantageously, the protective cover has, at its orifice for the passage of the screw head, a projecting portion extending along the longitudinal axis of the fastening screw, of a length at least equal to twice the length of the thickness of the screw head.

Thus, even assuming that the fastening screw would move slightly, for example after a long and particularly restrictive use of the vehicle, the screw head is encased in this protruding portion of the protective cover, in a kind of cylinder (having a section of oblong shape), particularly preventing it from coming into contact with or near other electrically conductive elements of the vehicle.

Advantageously, the protective cover covers, over the entire length of said cover, the bus bar and the body of the fixing screw.

By this characteristic, the present invention intends to overcome a disadvantage of the prior art.

Indeed, the protective covers of the state of the art do not cover the entire end of the bus bar on which they are attached. However, during an assembly, an accidental contact between the unprotected end of the bus bar and the body can occur, creating arcing that can lead to an aggravated short circuit. These arcs can cause serious injury to the operator (burns) and damage the part, rendering it unusable (removal of insulating material). According to a preferred embodiment, the system for fixing a bus bar of a motor vehicle according to the invention comprises a plurality of fixing screws and as many orifices respectively of the bus bar and the protective cover.

Indeed, according to the current technical specificities, each protective cover of a bus bar must embark two fixing screws, since each end of a bus bar is attached to two battery electrodes.

For the same purpose, the present invention also proposes a motor vehicle, characterized in that it comprises at least one system for fixing a bus bar as briefly described above.

Other aspects and advantages of the invention will appear on reading the following description of a particular embodiment given by way of non-limiting example and with reference to the accompanying drawings, in which:

- Figure 1 is a schematic top view of a bus bar on the end of which a protective cover according to the state of the art is attached;

- Figure 2 is a schematic bottom view of the bus bar and the protective cover according to the state of the art shown in Figure 1;

- Figure 3 is a schematic representation of a conventional bus bar;

- Figure 4 is a sectional view illustrating an embodiment of a protective cover according to the invention and a bus bar on which are fixed two fixing screws;

- Figure 5 is a schematic top view of a protective cover according to the invention and a bus bar on which are fixed two fastening screws;

- Figure 6 is a sectional view illustrating an alternative embodiment of a protective cover according to the invention and a bus bar on which are fixed two fastening screws; - Figure 7 is a sectional view illustrating another alternative embodiment of a protective cover according to the invention and a bus bar on which are fixed two fixing screws.

FIGS. 1 and 2 show, seen from above and from below, a bus bar 1 on which is fixed a protective cover 2 according to the prior art, the connection zone 3 of these two elements 1, 2 not being protected against electrically conductive contacts.

The power supply source mentioned above consists of a battery, not shown in the accompanying figures. This battery conventionally comprises two electrodes, one positive and the other negative, which are each respectively inserted into one of the two holes 1 1, 12 present at the two ends of a bus bar 1 (see FIG. ), a fixing screw then being screwed to maintain an electrically conductive contact between the bus bar and each of the electrodes. That is why it is so important to maintain and secure the position of use (screwed) of the fixing screw.

The primary object of the present invention is to keep the fixing screw in its position of use so that it becomes captive. Thus, the invention is not limited to a system necessarily using two fastening screws even if at present a source of electrical energy of a motor vehicle consists of a battery having two electrodes and therefore requiring two fixing screws . Thus, the problems of short circuits and arcs arise only when the two electrodes are connected, via an electrically conductive circuit (conductive materials such as fixing screws).

FIG. 4 shows an embodiment of the protective cover 4 according to the invention. In this sectional figure are shown two fixing screws 5, traditionally the number of screws required for the attachment of a bus bar 1. As can be seen in this figure, the fixing screws 5 extend along a longitudinal axis XX 'determined by the axis of the body 6 of screws 5.

The protective cover 4 covers here only partially the end of the bus bar 1 and does not cover the bodies 6 of screws 5. At the openings for the passage of the heads 7 of screws 5, the protective cover 4 has a protruding portion 8 or protruding substantially cylindrical enclosing the screw head 7 5. This portion 8 extends from the inner surface of the cover 4 , in contact with the bus bar 1, along the axis XX 'of the screw bodies 6. According to this embodiment, the height of this portion 8 is more than twice the thickness of the screw heads 7. 5. More specifically, in this embodiment, the height of this portion 8 is nearly three times greater than the thickness of the heads 7 fixing screw 5. Of course, the height of this portion 8 may vary but is preferably always greater than twice the thickness of a screw head to prevent contact of the screw head with another electrically conductive element.

As is apparent in FIG. 5, the openings of the cover 4 for the passage of the screw heads 5, as well as the aforesaid portion 8, have, in a horizontal section (plane perpendicular to the axis XX 'of the fastening screws 5), a section of oblong shape. In other words, the openings of the cover 4 have a length, along the axis ΥΎ, greater than its width, along the axis ZZ '. These oblong-shaped orifices are intended to be adapted to the position of the through-holes of the screw bodies 5 on the bus bars 1, knowing that the latter are conventionally offset from the center at the two ends of a bus bar 1, as is visible in Figure 3. Thus, preferably, the length of the openings of the cover 4 for the passage of the screw heads 7 have a length at least 1, 5 times greater than its width, the latter being equal (or lower) to the diameter of a screw head 5. The length of such a hole of the protective cover 4 (for the passage of the screw heads 5) can be up to twice its width.

In the first place, the present invention provides that the fixing screw 5 must not move throughout the cycle of use, so the invention proposes that the width of the opening of the protective cover 4 is at most equal to the diameter of the head 7 screw 5. Depending on the material used, more precisely its elastic nature or not, to form the protective cover 4, it can be expected that this width of the opening of the cover of protection 4 is less, at most one millimeter (mm) and at least 0.1 mm, to the diameter of the screw head 7 5.

Indeed, it is necessary that the fastening screw 5 can fully perform its function, during the anchoring of the protective cover 4 to the bus bar 1, that is to say that the fixing screw 5 must be able to be fully screwed so that the fixing of the bus bar 1 to the two electrodes is optimal. Thus, the friction and friction of the head 7 of screws 5 against the walls of the hole of the cover 4 should not be too large to impede the screwing but these mechanical means (clamping / friction) must be sufficient to ensure the retention of the fixing screw 5 (via its head 7) once it screwed.

This is why the material chosen to constitute the protective cover

4 should advantageously have, at least at its or holes or passage of heads 7 screw 5, a certain elasticity, especially when the width of the orifice is significantly lower (any proportion kept) to the diameter of the head 7 of screws 5.

Moreover, so that the protective cover 4 is easy to mount on the end of a bus bar 1 and that it can fit more easily on this part (respect of tolerances), the protective cover 4 consists of a plastic material, advantageously flexible. This advantageously flexible plastic material may consist of a thermoplastic or a thermosetting material.

This thermoplastic may consist of a polyolefin, for example a polyethylene (low or high density) or PVC, a polystyrenic, for example a high impact polystyrene, a cellulose acetate, or a polyimide.

The protective cover 4 may also consist of a thermosetting material, in particular a silicone (of the family of polyoranololsiloxanes).

In the embodiments shown in FIGS. 6 and 7, the protective cover 4 comprises a protective cap 9 to fulfill an identical function (electrical insulation and protection) with the screw bodies 6. In the embodiment shown in FIG. 6, this cap 9 extends, besides along the surface of the bodies 6 of screws 5, on all the surfaces of the end of the busbar 1 not covered by the hood. protection 4.

In the embodiment shown in FIG. 7, this cap 9 is in the form of two individual sleeves 10 each respectively covering a body 6 of screws 5.

It can be provided that this cap 9 or 10 is formed of an insulating material identical to or different from that of the protective cap 4.

The cap 9 or 10 is connected or not to the protective cover 4. In the case where the protective cover 4 includes, by connection, the cap 9 or 10, a particularly flexible material is advantageously chosen to form this or these elements 4, 9 or 10 so that the establishment of the assembly on the bus bar 1 is easy for an operator. Preferably, the cap 9 or 10 is not connected to the protective cover 4.

When the cap 9 or 10 consists of a separate element of the protective cover 4, the latter 9 or 10 is advantageously removable so that it can be removed once the assembly of the bus bars on the batteries made by an operator.

Such a protective cover 4, 9 or 10 according to the invention on the one hand to prevent any risk of electric arcs can damage the battery of the vehicle as hurting staff during assembly / assembly and on the other hand effectively protect against oxidation at the contacts, this especially if no coating is used (tin, nickel, etc.) to obtain a cost saving.

Claims

1. System for fastening a bus bar of a motor vehicle, comprising a busbar (1), an electrically insulating protective cover (4) for the bus bar (1) at least partially covering said busbar (1) and at least partially a fixing screw (5), comprising a body (6) and a screw head (7) for fixing between said bar (1) and a power source, the bus bar (1) and the protective cover (4) having an orifice for the passage respectively of the body (6) of screws (5) and the head (7) of screws (5), characterized in that the width of the orifice of the cover of protection (4) is at most equal to the diameter of the head (7) of screws (5).

2. System according to claim 1, characterized in that the width of the opening of the protective cover (4) is less than one millimeter, the diameter of the head (7) screw (5).

3. System according to claim 1 or 2, characterized in that the width of the opening of the protective cover (4) is at least 0.1 mm smaller than the diameter of the screw head (7) ( 5).

4. System according to any one of the preceding claims, characterized in that the orifice of the protective cover (4) has a section of oblong shape, the length of the orifice being greater than its width.

5. System according to claim 4, characterized in that the length of the opening of the protective cover (4) is at least equal to 1, 5 times its width.

6. System according to any one of the preceding claims, characterized in that the protective cover (4) is made of plastic.

7. System according to any one of the preceding claims, characterized in that the protective cover (4) has, at its orifice for the passage of the head (7) screw (5), a portion (8) protruding extending along the longitudinal axis (XX ') of the fixing screw (5), at least twice the thickness of the screw head (5).

8. System according to any one of the preceding claims, characterized in that the protective cover (4, 9, 10) covers, over the entire length of said cover (4), the bus bar (1) and the body (6). ) of the fixing screw (5).

9. System according to any one of the preceding claims, characterized in that it comprises a plurality of fixing screws (5) and as many orifices respectively of the bus bar (1) and the protective cover (4).

10. Motor vehicle, characterized in that it comprises at least one system for fixing a bus bar (1) according to any one of the preceding claims.