CN111095606A

CN111095606A - System for fastening a bus bar of a motor vehicle

Info

Publication number: CN111095606A
Application number: CN201880059817.2A
Authority: CN
Inventors: 斯尔维·罗拉斯; 安东尼·安德烈
Original assignee: PSA Automobiles SA
Current assignee: PSA Automobiles SA
Priority date: 2017-09-13
Filing date: 2018-07-30
Publication date: 2020-05-01
Also published as: FR3071108A1; EP3682491A1; FR3071108B1; WO2019053345A1; MA50228A

Abstract

A system for fastening a bus bar of a motor vehicle, the system comprising a bus bar (l), an electrically insulating protective cover (4) at least partially covering the bus bar (l) for protecting the bus bar (1), and at least one fastening screw (5) comprising a body (6) and a head (7) of the screw (5) for fastening between the bus bar (l) and the protective cover (4), the bus bar (1) and the protective cover (4) having an aperture for passing through the body (6) of the screw (5) and the head (7) of the screw (5), respectively, the width of the aperture of the protective cover (4) being at most equal to the diameter of the head (7) of the screw (5). The invention also relates to a motor vehicle comprising such a system for fastening a busbar.

Description

System for fastening a bus bar of a motor vehicle

Technical Field

The present invention relates to a system for fastening a bus bar of a motor vehicle. More specifically, the invention aims to propose a solution for fastening and electrically protecting and isolating a special type of cable of a motor vehicle, of the type used to carry high voltages (≧ 450 volts), with consequent specific risks, known as busbars or busbars.

Background

An electric machine such as an electric vehicle or a hybrid vehicle includes a battery pack having a plurality of battery cells. Therefore, the battery pack includes a plurality of battery cells in which positive electrodes and negative electrodes are disposed adjacent to each other, and the positive electrodes and the negative electrodes of two adjacent battery cells are coupled to each other by bus bars. Therefore, the battery pack is constructed by connecting all the battery cells in series, so that a high output voltage (≧ 450 volts) can be delivered.

The bus bars for the battery pack usually have the form of rigid bars formed of a conductor made of, for example, copper, which is covered with an insulating material over its entire length. The bus bar has a pair of two holes at both ends thereof, and the negative electrodes and the positive electrodes of the two batteries are inserted into the two holes. The bus bars are positioned in an optimized manner in the cell environment (narrow areas, curved channels, etc.).

In a battery pack, a plurality of bus bars are typically held together by a non-conductive support. The support includes a plurality of insulating boots each secured to an end of the bus bar. Generally, such a protective cover allows to avoid any physical contact with a portion of the bus bar (its end).

Thus, patent EP 1872421 is known, which describes a box or support for connecting busbars or busbars comprising an insulating protective cover. Patent EP 2688122 is also known, which describes a wiring module comprising a busbar or busbar, which wiring module comprises an insulating element having one or two oblong connecting holes.

The protective cover should also be equipped with a fastening screw adapted to maintain and stabilize the tight connection between the battery electrode and the bus bar. These fastening screws must therefore be forcibly held in place once they have been fastened, in order firstly to ensure a good electrical connection between the electrodes and the bus bars, but also to avoid short circuits due to contact with other conductive elements, which would lead to irreversible degradation of the battery, in particular to the generation of arcs.

However, such fastening screws are subjected to a great deal of and intense mechanical stress during the transport and mounting cycles of the bus bar, with the risk of losing the fastening screw before mounting on the vehicle.

Disclosure of Invention

The present invention aims to propose a simple and economical solution to permanently stabilize the position of these fastening screws when they are tightened, ensuring the fixing of the bus bar to the electrode and the fixing of the protective cover to the bus bar.

To this end, the invention proposes a system for fastening a bus bar of a motor vehicle, comprising a bus bar, an electrically insulating protective cover for protecting the bus bar at least partially covering the bus bar, and at least one fastening screw comprising a main body and a screw head, for fastening between the bus bar and an electrical power supply source, the bus bar and the protective cover having apertures for passing the screw main body and the screw head, respectively, the system being characterized in that the width of the aperture of the protective cover is at most equal to the diameter of the screw head.

By means of the invention, once the fastening screw is in its fastening position, it is restrained by the fastening and by the friction generated by the protective cover at the contact of its screw head with the aperture wall of the protective cover, so that it no longer moves throughout the use of the vehicle (battery or bus bar), whatever the driving conditions of the motor vehicle.

Thus, on the one hand, the fastening between the bus bar and the electrode is ensured, and on the other hand, the close contact of the cover and the screw head ensures the fastening of the screw and the fastening of the protective cover at the end of the bus bar.

The advantage of the invention is that no additional components are used, so that the solution is both economical and simple (no increase in the weight of the vehicle).

Another advantage is that the cover also allows to avoid the fastening screws being lost in case they are accidentally loosened during use of the vehicle.

Preferably, the width of the hole of the protective cover is at most one millimeter smaller than the diameter of the screw head.

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

Advantageously, the opening of the protective cover has an oblong cross-section, the length of which is greater than its width.

Currently, the protective covers of the prior art require the use of double sets of tools, since the apertures (for the passage of the fastening screw heads) are not symmetrically provided at the ends of the bus bars. In practice, these apertures are sometimes shifted to the right and sometimes to the left on the bus bars (cf.

references

11 and 12 in fig. 3 showing such bus bars).

Thus, by providing an oblong aperture, no more tools need to be used, as the protective cover is adapted to any of the ends of the bus bar, regardless of the arrangement of the aperture on the bus bar. For example, if thirty bus bars are considered, there would be about sixty sets of tools (one on each side) according to the prior art, whereas according to the solution of the invention only six sets of tools are required.

This advantageous feature of the invention therefore allows to reduce the variety of tool parts used and therefore to reduce the tool costs. In addition, this solution saves assembly time.

More specifically, it is preferred that the length of the bore 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 a plastic material.

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

Thus, even if the fastening screw is assumed to move slightly after use of the vehicle for a long time and under special conditions, for example, the screw head is enclosed in the cylindrical projecting portion (having an oblong cross section) of the protective cover, in particular is prevented from contacting or coming close to other conductive elements of the vehicle.

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

By this feature, the present invention aims to remedy the drawbacks of the prior art.

In fact, the prior art protective cover does not cover the entire end of the bus bar to which it is fixed. However, during assembly, accidental contact between the unprotected end of the bus bar and the vehicle body may occur, thereby forming an arc that may cause a severe short circuit. These arcs can cause serious injury (burns) to the operator and damage the parts, rendering them unusable (removal of the insulation).

According to a preferred embodiment, the system for fastening a bus bar of a motor vehicle according to the invention comprises a plurality of fastening screws and as many apertures from the bus bar and the protective cover, respectively.

In fact, according to the current specifications, since each end of the bus bar is fastened to two battery electrodes, each protective cover of the bus bar must be fitted with two fastening screws.

The invention also proposes, for the same purpose, a motor vehicle characterized in that it comprises at least one system for fastening a busbar as briefly described above.

Drawings

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

fig. 1 is a schematic top view of a bus bar, at the ends of which a protective cover according to the prior art is fastened;

fig. 2 is a schematic bottom view of the bus bar and the protective cover according to the prior art shown in fig. 1;

FIG. 3 is a schematic view of a conventional bus bar;

fig. 4 is a cross-sectional view showing an embodiment of the protective cover according to the invention and a bus bar on which two fastening screws are fastened;

fig. 5 is a schematic top view of the protective cover and the bus bar according to the invention, on which two fastening screws are fastened;

fig. 6 is a cross-sectional view showing an embodiment variant of the protective cover according to the invention and a bus bar to which two fastening screws are fastened;

fig. 7 is a sectional view showing another embodiment variant of the protective cover according to the invention and a bus bar to which two fastening screws are fastened.

Detailed Description

Fig. 1 and 2 show a bus bar 1 in a top view and a bottom view, on which bus bar 1 a protective cover 2 according to the prior art is fastened, the connection region 3 of the two

elements

1, 2 being unprotected against conductive contact.

The power supply source mentioned above is constituted by a battery, which is not shown in the drawings. The battery generally comprises two electrodes, one positive and the other negative, each inserted into one of two apertures 11, 12 (see fig. 3) at the two ends of the bus bar 1, respectively, and then a tightening screw will be tightened to maintain conductive contact between the bus bar and each of the electrodes. Therefore, it is important to maintain and stabilize the use (fastening) position of the fastening screw.

The primary object of the present invention is to hold the fastening screw in its position of use so that it is in the way. Therefore, even if the current power supply for motor vehicles is constituted by a battery with two poles and therefore requires two fastening screws, the invention is not limited to systems in which two fastening screws must be used. Therefore, the problems of short circuits and arcs only occur when the two electrodes are connected via a conductive circuit (conductive material such as a fastening screw).

Fig. 4 shows an embodiment of the protective cover 4 according to the invention. The cross-section shows two fastening screws 5, typically the number of screws required to fasten the bus bar 1. As shown in this figure, the fastening screw 5 extends along a longitudinal axis XX', which is determined by the axis of the body 6 of the screw 5.

Here, the protective cover 4 only partially covers the end of the bus bar 1 and does not cover the body 6 of the screw 5. At the opening for the passage of the head 7 of the screw 5, the protective cover 4 has a substantially cylindrical projecting or protruding portion 8, which portion 8 surrounds the head 7 of the screw 5. This portion 8 extends from the inner surface of the cover 4 in contact with the busbar 1 along the axis XX' of the body 6 of the screw 5. According to this embodiment, the height of the portion 8 is greater than twice the thickness of the head 7 of the fastening screw 5. More precisely, in this embodiment, the height of this portion 8 is approximately three times the thickness of the head 7 of the fastening screw 5. Of course, the height of this portion 8 may vary, but is preferably always greater than twice the thickness of the head of the screw, in order to prevent any contact of the head of the screw with other conductive elements.

As shown in fig. 5, the aperture of the cap 4 for the passage of the head 7 of the screw 5 and the above-mentioned portion 8 have an oblong section along a horizontal section (plane perpendicular to the axis XX' of the fastening screw 5). In other words, the length of the aperture of the cap 4 along the axis Y 'Y is greater than its width along the axis ZZ'. As shown in fig. 3, since the hole for passing the main body 6 of the screw 5 on the bus bar 1 is usually offset toward both ends of the bus bar 1 with respect to the center, the oblong hole is suitable for the position of the hole for passing the main body 6 of the screw 5 on the bus bar 1. Therefore, preferably, the length of the aperture of the cap 4 for the head 7 of the screw 5 to pass through is at least 1.5 times its width, which is equal to (smaller than) the diameter of the head 7 of the screw 5. The length of such an aperture of the protective cover 4 (for the head 7 of the screw 5 to pass through) may be up to twice its width.

Firstly, the invention sets that the fastening screw 5 should not move throughout the use cycle, and moreover, it proposes that the width of the aperture of the protective cover 4 is at most equal to the diameter of the head 7 of the screw 5. Depending on the material used, more precisely on whether it has elastic characteristics, in order to form the protective cover 4, this width of the aperture of the protective cover 4 can be set at most one millimeter (mm) smaller and at least 0.1mm smaller than the diameter of the head 7 of the screw 5.

In fact, the fastening screw 5 needs to be fully functional when fixing the protective cover 4 to the bus bar 1, that is, the fastening screw 5 should be fully fastenable, so that the fastening of the bus bar 1 on both electrodes is optimal. Thus, the friction of the head 7 of the screw 5 with respect to the wall of the aperture of the cap 4 should not be so great as to affect the fastening, however these mechanical means (fastening/friction) must be sufficient to ensure that the fastening screw 5 is retained (by its head 7) after the fastening of the fastening screw 5.

Advantageously, therefore, the material chosen to constitute the protective cover 4 must have a certain elasticity at least at the one or more apertures for the passage of the head 7 of the screw 5, in particular when the width of the aperture (any retention ratio) is significantly smaller than the diameter of the head 7 of the screw 5.

In addition, in order to make it easy for the boot 4 to be mounted on the end of the bus bar 1 and for the boot 4 to be more easily adapted to the component (to conform to tolerances), the boot 4 is made of a plastic material, which is advantageously flexible. Such a plastic material, which is advantageously flexible, may be composed of a thermoplastic or thermosetting substance.

The thermoplastic may be made of polyolefins such as polyethylene (low density or high density) or PVC, polystyrene such as high impact polystyrene, cellulose acetate or polyimide.

The protective cover 4 can also be made of a thermosetting material, in particular silicone (belonging to the polyorganosiloxane family).

In the embodiment shown in fig. 6 and 7, the protective cover 4 comprises a protective sheath 9 to fulfil the same function (electrical insulation and protection) for the body 6 of the screw 5.

In the embodiment shown in fig. 6, this sheath 9 extends over all the surfaces of the end of the bus bar 1 not covered by the protective cover 4, in addition to extending along the surface of the body 6 of the screw 5.

In the embodiment shown in fig. 7, the sheath 9 takes the form of two separate sleeves 10, the sleeves 10 each covering the body 6 of the screw 5.

It may be provided that the

sheath

9 or 10 is formed of an insulating material which is the same as or different from the material of the protective cover 4.

The

sheath

9 or 10 is or is not connected to the protective cover 4. In the case where the protective cover 4 comprises a

sheath

9 or 10 by means of a connection, it is advantageous to choose a particularly flexible material for the one or

more elements

4, 9 or 10, so as to make it easy for the operator to mount the assembly on the busbar 1. Preferably, the

sheath

9 or 10 is not connected to the protective cover 4.

When the

sheath

9 or 10 constitutes an element distinct from the protective cover 4, advantageously, the

sheath

9 or 10 is detachable so that the

sheath

9 or 10 can be removed when the operator finishes assembling the bus bar to the battery.

Such a

protective cover

4, 9 or 10 according to the invention allows on the one hand to prevent all risks related to electric arcs that could damage the vehicle battery, for example to injure personnel during installation/assembly, and on the other hand to effectively prevent oxidation at the contacts, in particular without using any coating (tin, nickel, etc.) to save costs.

Claims

1. A system for fastening a bus bar of a motor vehicle, comprising a bus bar (1), an electrically insulating protective cover (4) covering at least partially the bus bar (1) for protecting the bus bar (1), and at least one fastening screw (5) comprising a body (6) and a head (7) of the screw (5) for fastening between the bus bar (1) and an electrical power supply, the bus bar (1) and the protective cover (4) having an aperture for passing through the body (6) of the screw (5) and the head (7) of the screw (5), respectively, characterized in that the width of the aperture of the protective cover (4) is at most equal to the diameter of the head (7) of the screw (5).

2. The system according to claim 1, characterized in that the width of the aperture of the protective cover (4) is at most one millimeter smaller than the diameter of the head (7) of the screw (5).

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

4. System according to any one of the preceding claims, characterized in that the aperture of the protective cover (4) has an oblong cross-section, the length of which is greater than its width.

5. System according to claim 4, characterized in that the length of the aperture 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 material.

7. System according to any one of the preceding claims, characterized in that the protective cover (4) has, at the aperture for the passage of the head (7) of the screw (5), a projecting portion (8) extending along the longitudinal axis (XX') of the fastening screw (5), the length of which is at least equal to twice the thickness of the head (7) of the screw (5).

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

9. System according to any one of the preceding claims, characterized by comprising a plurality of fastening screws (5) and as many apertures from the bus bar (1) and the protective cover (4), respectively.

10. A motor vehicle, characterized in that it comprises at least one system for fastening a busbar (1) according to any one of the preceding claims.