Protective structure for an electric battery and motor vehicle including such a protective structure

Abstract

Protective structure for an electric battery and motor vehicle comprising such a protective structure. Protective structure for an electric battery in a motor vehicle having a longitudinal axis (X), a transverse axis (Y) and a vertical axis (Z), the protective structure comprising a support cross member (6) and a protector (10) together defining a housing (LG) for housing an electric battery, the protector comprising at least one first protective flange (1) intended to deform by dissipating energy under the application of a force along the longitudinal axis, the protector comprising an upper connecting strip (3) connected at least to the first protective flange, the protective structure comprising at least four screw fixings for connecting the protector to the support cross member (6), the protective flange (1) having a first dimension (L1) along the longitudinal axis,at least 10% larger than the (LBX) dimension of the electric battery along the longitudinal axis. Figure from the abstract: Fig. 3,

Description

Title of the invention: Protective structure for an electric battery and motor vehicle comprising such a protective structure

[0001] The present invention relates to a protective structure for an electric vehicle battery. This protective structure is intended to protect the mechanical integrity of the battery, particularly in the event of a frontal collision involving the vehicle.

[0002] We are particularly interested here in motor vehicles that have a reduced front overhang. We are particularly interested here in commercial vehicles with a reduced front overhang.

[0003] The battery in question here is a service battery which powers a number of electronic devices and which must remain functional after the occurrence of an accident, in particular a frontal impact, in particular to be able to power the unlocking of the doors, the hazard lights of the vehicle, the emergency call functionality, etc.

[0004] The term 'crash' has become established, in the language of the trade and in common language, as an equivalent of a situation of accidental shock.

[0005] In particular, the term "crash test" refers to an accidental impact test performed on a vehicle under predefined conditions. There is a series of reference crash tests, some of which are of particular interest for the purposes of this document.

[0006] In known vehicle configurations, the electric battery, if located in the engine compartment at the front, is not directly exposed to rupture by penetration from another mechanical element of the vehicle or even from a foreign body, because the sufficiently large front overhang allows the battery to be housed away from areas severely damaged by the impacts of the reference crash tests.

[0007] In other known vehicle configurations, the electric battery is located in another part of the vehicle, less vulnerable to the consequences of a frontal impact.

[0008] Furthermore, a type of vehicle, or more broadly a technical vehicle platform, must be developed with a left-hand drive version, i.e. with the steering wheel placed to the left of a vertical median plane of the vehicle, and with a right-hand drive version, i.e. with the steering wheel placed to the right of the vertical median plane of the vehicle.

[0009] The protection of the auxiliary battery must be ensured for both the left-hand drive version and the right-hand drive version.

[0010] The inventors sought to propose a solution that would allow the auxiliary battery to be placed in the front engine compartment, in a configuration with a reduced front overhang, thereby preventing substantial damage to the auxiliary battery during the impacts of the reference crash tests. Optionally, the proposed solution could be suitable for both right-hand and left-hand drive vehicles.

[0011] To this end, a battery protection structure for an electric vehicle is proposed here having a longitudinal axis, a transverse axis and a vertical axis, the protection structure comprising a support cross member (6) and a protector (10) together defining a housing for an electric battery, the protector comprising at least a first protective flange (1) intended to deform by dissipating energy under application of a crash force along the longitudinal axis, the protector comprising an upper connecting band (3) connected at least to the first protective flange, the protection structure comprising at least four screw fixings for connecting the protector to the support cross member, the protective flange having a first dimension (L1) along the longitudinal axis, at least 10% greater than the dimension (LBX) of the electric battery along the longitudinal axis.

[0012] Expressed in another formulation, the first protective flange forms a small spar typically between 20 cm and 30 cm long (longer than the X dimension of the battery). This spar acts as a shock-absorbing element, protecting the battery in a frontal impact configuration. The first protective flange can be described as 'lateral' because it is located near a side wall of the battery. The first protective flange extends along the longitudinal axis, and it is in this direction that the crushing occurs, allowing it to absorb energy.

[0013] It turns out that in the absence of such a protective element, in a vehicle configuration with a low front overhang, the battery is substantially damaged, in particular by the 'barrier' crash test at 56 km / h or the 'pole' crash test, and the electrical functions which are supported by the auxiliary battery may no longer be ensured from the moment of the crash.

[0014] Thanks to the arrangements proposed above, a configuration of a motor vehicle with a reduced front overhang, typically less than 850 millimeters, is obtained, with a service battery located in the front engine compartment, said service battery being protected by the proposed protective structure, at least for a subset of reference crash tests.

[0015] It is also noted that the first fender flange, as it recoils under the impact of the crash, comes to rest against a component of the vehicle's bulkhead, which is a structural element of the vehicle that separates the passenger compartment from the front engine compartment. In other words, the fender flange bottoms out against an X-shaped stop and then collapses along the X-axis.

[0016] The term "defense flange" expresses the function of defense and protection provided to the electric battery against potential mechanical damage from the front of the vehicle, caused by the consequences of a frontal impact. The terms "defense frame" or "defense / protection beam" could just as easily have been used.

[0017] Regarding the terminology "front engine compartment", this term is used regardless of the type of engine, e.g. thermal, hybrid or electric.

[0018] It is noted that the service battery can be of the lead type or of the lithium-ion type, and more generally the battery can be of any electrochemical type.

[0019] According to an advantageous embodiment, the protector may further comprise a second defensive flange designed to deform by dissipating energy under the application of a crash force along the longitudinal axis, the first and second defensive flanges framing the electric battery along the transverse axis.

[0020] Thus, the battery is protected on both sides (left and right), improving the symmetry of the protection. Furthermore, the energy absorbed by the deformation of the two protective flanges is increased.

[0021] In practice, the housing is delimited on the right and left by the first and second defensive flanges. It should be noted that the housing is generally prismatic and parallelepiped-shaped. It should also be noted that the housing leaves a free space at the front of the battery, as will be explained in more detail later.

[0022] The two defense flanges are parallel to each other. They generally extend in an XZ plane.

[0023] In this configuration, the upper connecting strip is connected to both the first and second defense flanges.

[0024] According to one embodiment, along the vertical axis, the height of the first and second defense flanges is at least equal to 60% of the height of the service battery, preferably at least 70% of the height of the battery.

[0025] According to one embodiment, in the area of ​​the auxiliary battery's electrical terminals, the first and second protective flanges remain lower than the auxiliary battery's electrical terminals. This reduces the risk of the protector contacting the electrical terminals, even in the event of local deformations.

[0026] According to one embodiment, the upper connecting strip does not cover the electrical terminals of the auxiliary battery. As mentioned previously, here too we This reduces the risk of the protector coming into contact with the electrical terminals, even in the event of local deformations.

[0027] According to one embodiment, the protective structure may further include a front plate connecting the front edges of the first and second defense flanges.

[0028] Wherefore, the entire front face of the auxiliary battery can be protected from point mechanical damage. The side faces and the front face are delimited by protective plates of the guard.

[0029] It turns out that this front plate prevents any perforation of the battery, which is a determining criterion in the case where the auxiliary battery is of the lithium-ion type.

[0030] According to one embodiment, the height of the front plate is identical or similar to the height of the first and second fender flanges. Alternatively, the front plate may be higher than the height of the side fender flanges.

[0031] According to one embodiment, the protective structure further includes a liquid retention tray.

[0032] The presence of the tray is compatible with the configuration of the protective structure. The tray is located primarily under the battery and includes raised edges. The protector's fasteners pass through the tray's mounting brackets or even directly through the tray itself to screw into the support crossmember.

[0033] According to one embodiment, the protector is a single piece of sheet metal manufactured by cutting and bending from a thick sheet blank, with a thickness between 2 mm and 2.5 mm.

[0034] This is therefore a part that is easy to manufacture with an available process and a reasonable cost price.

[0035] In addition, folds forming reinforcing ribs may be provided. These reinforcing ribs advantageously extend along the longitudinal axis X.

[0036] According to one embodiment, a predetermined minimum distance is provided separating the positive and negative terminals of the auxiliary battery from the nearest cell of the protector. A value of 25 mm can be chosen for the predetermined minimum distance.

[0037] This minimum distance helps to avoid unwanted contact of one of the battery terminals, in particular the positive terminal, with an external metallic element, which would cause a short circuit.

[0038] According to one embodiment, the four (or more) fixings both the protector and the retention tray on the support crossmember, and / or on a body element of the vehicle.

[0039] In other words, the same fasteners secure both the protector and the tray. Thus, adding the protector does not lead to an increase in the number of fasteners.

[0040] According to one embodiment, the upper connecting strip includes attachment elements for fixing a fuse box. In this way, the protector integrates functions in addition to the pure protection function, for fixing auxiliary elements such as a primary fuse box or a circuit breaker, a plastic terminal cover, or any other element connected to the electrical distribution head that originates from the auxiliary battery.

[0041] The present invention also relates to a motor vehicle, having a longitudinal axis, a transverse axis and a vertical axis, preferably electric or hybrid, with a front overhang of less than 850 mm, the vehicle comprising an electric auxiliary battery arranged in a front overhang area, the vehicle comprising a protective structure as described above.

[0042] Advantageously, the protective structure thus makes it possible to place the auxiliary battery in the front engine compartment, whereas the low value of the front overhang makes this position unfavorable a priori.

[0043] The present invention also relates to an assembly comprising at least a first motor vehicle as described above and a second motor vehicle as described above, the first motor vehicle being of the left-hand drive type and the second motor vehicle being of the right-hand drive type, characterized in that the position of the electric auxiliary battery is identical for the first and second vehicles.

[0044] Wherefore, we have a single position of the auxiliary battery, regardless of the position of the steering wheel, namely on the right or on the left, which makes it possible to rationalize the diversity of parts and to reduce design time.

[0045] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig. 1] schematically represents in profile a front area of ​​a vehicle with a low overhang; - [Fig.2] schematically represents, in front view, the front area of ​​the vehicle of the [Fig.l]; - [Fig.3] schematically represents a battery in perspective view protected by an example of a protective structure according to the present invention; - [Fig.4] schematically represents, in perspective view, another example protective structure; - [Fig.5] schematically represents a side view of a service battery as well as the protector that protects it, in a normal state; - [Fig.6] is analogous to [Fig.5] and represents the auxiliary battery and the protector in a post-crash state; - [Fig.7] schematically represents the battery tray and the fixings; - [Fig.8] represents a fuse box mounted on the connection strip superior ; - [Fig.9] represents a top view of the battery area before the crash and after the crash.

[0046] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0047] Figures 1 and 2 show a front portion of a motor vehicle VH. The motor vehicle in question is a utility vehicle. It could be, for example, a van, a panel van, or a minibus.

[0048] With regard to the location of the vehicle elements in space, as is customary in the trade, the X direction corresponds to the longitudinal direction of the vehicle, the Z direction corresponds to the vertical direction relative to the local ground and the Y direction, perpendicular to the two previous ones, corresponds to the transverse direction of the vehicle.

[0049] The terms 'front' and 'rear' are understood in relation to the longitudinal direction X, considering that the front corresponds to the vehicle's usual movement. The terms 'up' and 'down' are relative to the vertical direction Z.

[0050] The terms 'left' and 'right' are appreciated with respect to the transverse direction Y when looking along the longitudinal direction forwards.

[0051] The vehicle in question has an overall height of at least 160 cm, most often at least 170 cm.

[0052] The VH vehicle includes a front engine compartment, which contains a front axle drive element of the vehicle, this drive element being able to be a thermal engine, a hybrid powertrain, or a pure electric motor.

[0053] The VH vehicle is characterized by a short front overhang, denoted PAFAV. Generally, the front overhang PAFAV is less than 850 mm. Preferably, the front overhang PAFAV is less than 800 mm. In specific configurations of interest, the front overhang PAFAV is on the order of 750 mm.

[0054] As a reminder, with reference to [Fig.1], the front overhang is defined by the distance in X which separates the axis XI of the front wheels from the most anterior part, i.e. located furthest forward of the vehicle.

[0055] In the configuration of interest, it is understood that the engine compartment has a fairly generous space in the vertical direction Z but a very constrained space in the longitudinal direction X.

[0056] Furthermore, in the case of a utility vehicle, the entire cargo space behind the driver's compartment is generally dedicated to usable cargo volume, and therefore it is avoided to place bulky components such as the auxiliary battery in a space behind the driver's compartment. It should be noted that it is possible to have the traction battery (the main battery in a zero-emission vehicle) located in the vehicle floor, i.e., under the usable cargo volume.

[0057] It is therefore necessary to deal with a constraint regarding the placement of the auxiliary battery, identified as BAT, in the front engine compartment.

[0058] Figures 1 and 2 illustrate the position of the vehicle apron marked TAB which separates the front engine compartment from the driver's compartment (also 'cab' for some utility vehicles where the cargo volume is separated from the driver's compartment).

[0059] The vehicle is equipped with a front crossmember TA that extends transversely in a position just behind the bumper. This front crossmember TA is structurally connected to right and left side members as known and therefore not described in detail here. The front crossmember TA is one of the essential contributors to protection in a frontal collision configuration.

[0060] The impact of the front shock is identified CR in figures 1, 4 and 9.

[0061] The front axle of the vehicle includes a left wheel marked LW and a right wheel marked RW.

[0062] The auxiliary battery BAT rests on a support cross member 6. The support cross member 6 is a metal piece which extends transversely, that is to say generally in the Y direction from one side to the other, connected to body elements belonging to the vehicle.

[0063] The support crossmember 6 acts as a shelf on which accessory components of the vehicle systems, including the thermal management system, are placed. Some accessory components are fixed under the support crossmember. The support crossmember 6 is described as a multi-function crossmember.

[0064] As regards the service battery BAT, it rests on the support cross member 6, in a position to the right of the longitudinal vertical median plane PML (Y=0) as seen in [Fig.2].

[0065] The auxiliary battery BAT includes in its upper part a positive terminal B+ and a negative terminal B-.

[0066] The positive and negative terminals are generally aligned along the transverse Y direction. The terminals are located on the front side.

[0067] From another point of view, in view of the requirement for compactness in X, the smallest dimension of the battery (denoted here LBX) is aligned on the longitudinal axis X. LBX can be between 160 mm and 180 mm.

[0068] The length of the battery, directed along the transverse axis Y, is denoted LBY. LBY is generally greater than LBX.

[0069] The height of the battery is noted as HB.

[0070] Advantageously according to the present invention, the battery benefits from a protective structure which preserves its integrity in the event of a front impact suffered by the vehicle.

[0071] The protective structure is based on the support cross member 6 already described. A protector 10 is also provided, which will be described in the following paragraphs.

[0072] In the illustrated example, the protector comprises a first defensive flange 1, located to the left of the battery, and a second defensive flange 2 located to the right of the battery. The first and second defensive flanges frame the battery along the transverse axis Y. The first and second defensive flanges are not necessarily in contact with the side walls of the battery, but they are located a short distance from the side walls of the battery, say a few millimeters away.

[0073] Indeed, advantageously, it is possible to remove the battery without removing the protector 10, and it is also possible to install a new battery without removing the protector.

[0074] The height H2 of the flanges is less important than the height HB of the battery as can be seen in figures 3 and 5.

[0075] For example, the height of the first and second defense flanges is at least equal to 60% of the height of the service battery, preferably at least 70% of the height of the battery, but remains less than 80% of the height of the service battery.

[0076] As can be seen in figures 3 and 4, the lower limit in Z of each defense flange does not necessarily coincide with the lower limit of the battery, because in fact a recovery tray is planned to be housed in the lower part of the battery which will be discussed below.

[0077] Thus the lower limit of each defense flange can be at a vertical elevation which is above the lower limit of the service battery.

[0078] In addition, there is a top connecting band 3 which is connected to both the first defense flange 1 and the second defense flange 2.

[0079] To achieve this, the upper connecting strip includes vertical flaps. A left vertical flap, designated 3g, and a right vertical flap, designated 3d, are thus provided.

[0080] The upper connecting band 3 adjoins the upper face of the battery. The upper connecting band provides an enveloping effect and prevents any overturning of the battery under shock.

[0081] It is noted that the upper connecting band does not directly participate in the protection against crushing along X, but it allows the defense flanges to be kept in the appropriate position during the beginning of the impact until the moment when the flanges are contacted by the front cross member or another element which crushes them in X.

[0082] The protector 10 is in one example a single piece of sheet metal manufactured by cutting and bending from a thick sheet blank, with a thickness between 2 mm and 2.5 mm.

[0083] The thickness is determined by the expected resistance of the defense flanges to X-shaped crushing.

[0084] The left fender flange 1 includes a front edge 1a. The right fender flange 2 includes a front edge 2a. Each front edge includes a bent return forming a vertical front band that extends in the YZ plane. We will see the purpose of this later.

[0085] It is possible to provide on each defense flange one or more X-shaped stiffening rib(s) 22.

[0086] It is noted that it is possible to add a lining to the defense flanges, in addition to or as an alternative to the ribs.

[0087] The protector 10 is provided with rear tabs 32 which include a horizontal flat with a hole and which allow fixing by screwing onto the support cross member 6. It is noted that the rear tabs 32 extend outwards in the transverse direction relative to the battery housing.

[0088] In addition, the protector 10 is provided with front tabs 34,35 which also each include a horizontal flat with a hole for receiving a screw fixing on the support cross member 6. It is noted that the rear tabs 32 extend inwards in the transverse direction relative to the battery housing.

[0089] The support cross member 6 and the protector 10 together define an LG housing for housing a battery.

[0090] As illustrated in [Fig. 5], the normal length of each fender flange is denoted LC. As illustrated in [Fig. 6], after crushing resulting from a frontal impact, the length of each fender flange is reduced to L1C. The deformation associated with this reduction in length allows for significant energy absorption and provides protection of the mechanical integrity of the electric battery.

[0091] In the normal state, the defense flanges 1,2 protrude forward relative to the front face of the battery by a dimension LD as seen in [Fig.5]. There may also be a rearward protrusion.

[0092] In the event of an impact, the overshoot of dimension LD is reduced to a low value, or even to 0 (see figures 6 and 9).

[0093] It is noted that in one embodiment, there is no rear face in the protector. This is made possible by the absence of mechanically aggressive elements placed at the rear of the battery.

[0094] In addition to the protector, a liquid effluent retention tray for the battery is provided. This tray, designated 5, is made of plastic and contributes marginally to the mechanical protection of the battery.

[0095] The tank includes a low depression forming a sump to collect the liquid effluents that may have escaped from the battery and direct them via a pipe 95 to the ground.

[0096] In addition, a 93 gaseous effluent evacuation line is also provided, leading from the top of the battery to the recovery tank 5.

[0097] In the illustrated example, the protector 10 is fixed to the support cross member by 4 fixings, namely a rear left fixing 72 with axis A2, a rear right fixing 73 with axis A3, a front right fixing 74 with axis A4, and a front left fixing 75 with axis A5.

[0098] An internal fastener 71 is also provided for attaching the tray to the support crossmember. A screw 92 and a metal plate 91, as previously known, are also provided for securing the battery in place. The screw 92 is screwed into a tapped hole with axis A9 provided in the support crossmember 6.

[0099] In addition, means for fixing a fuse box are arranged on the upper connecting strip 3. More specifically, in the illustrated example, a first welded stud 81 and a second welded stud 82 are provided which form attachment elements (81,82) for fixing a fuse box marked 8 as shown in [Fig.8].

[0100] In an optional embodiment, the protector is supplemented by a front plate 4 connecting the front edges of the first and second defense flanges.

[0101] This front plate 4 may or may not be installed depending on the type of battery to be protected. According to one embodiment, such a front protection plate is installed when the auxiliary battery is of the lithium type.

[0102] More specifically, the front plate 4 includes a left edge 4g assembled to the front edge of the left fender flange, and a left edge 4d assembled to the front edge 2a of the right fender flange 2.

[0103] The front edge of the front plate includes a vertical front band 17 which receives the left edge 4g of the front plate 4 in a flat position. The front edge 2a of the other flange includes also a front vertical band 27 which receives flat the right edge 4d of the front plate 4.

[0104] The vertical front bands 17,27 on each side allow, in the event of an impact, to equalize the forces transmitted by the front plate 4 towards the defense flanges 1 and 2.

[0105] Assembly can be done simply with screws 47 as in the illustrated example, but any other preferably removable means of assembly may be used.

[0106] Note that the front plate 4 must be removed in order to remove the electric battery.

[0107] Furthermore, the front plate 4 can be fitted with stiffeners 42.

[0108] In addition or as an alternative, the front plate 4 can be formed as a lining part, namely two folded sheets joined together by welding.

[0109] The protector 10, and the front plate 4 when present, are made of steel with a substantial yield strength, preferably of high yield strength steel.

[0110] According to one option, the anti-corrosion treatment applied to the other body and chassis parts is applied to the protector and the front plate.

[0111] In [Fig.9], the nominal situation is illustrated in solid lines in top view and We have further illustrated in dotted line the situation after a front impact, with the first defence flange 1 crushed and shortened (reference 1CR) along X, the second defence flange 2 crushed and shortened (reference 2CR) along X, the battery which has moved back a little to the position BATCR.

[0112] So no, the dimensioning of the overhang length LD can be expressed absolutely, for example, LD can be between 35 mm and 55 mm. Alternatively, the overhang length LD can be expressed as a relative value. For example, LD can be between 10% of LBX and 15% of LBX.

[0113] Depending on the configurations and crash tests, it may turn out that the presence of a single defensive flange, in particular the left flange, is sufficient to provide the desired protection for the auxiliary battery.

[0114] Thus, the battery is protected by the presence of at least one defensive flange; it is not always necessary to have both flanges on either side of the battery as illustrated in the figures and discussed above.

[0115] A first left-hand drive motor vehicle and a second right-hand drive motor vehicle are planned. The position of the auxiliary electrical battery is identical for the left-hand drive vehicle and for the right-hand drive vehicle.

[0116] It is noted that the present invention can be applied to vehicles other than utility vehicles, for example small urban vehicles.

Claims

Demands

1. Electric battery protection structure in a motor vehicle having a longitudinal axis (X), a transverse axis (Y) and a vertical axis (Z), the protection structure comprising a support cross member (6) and a protector (10) together defining a housing (LG) for housing an electric battery, the protector comprising at least a first defense flange (1) intended to deform by dissipating energy under application of a force along the longitudinal axis, the protector comprising an upper connecting band (3) connected at least to the first defense flange, the protection structure comprising at least four screw fixings for connecting the protector to the support cross member (6), the defense flange (1) having a first dimension (L1) along the longitudinal axis, at least 10% greater than the dimension (LBX) of the electric battery along the longitudinal axis.

2. Protective structure according to claim 1, wherein the protector further comprises a second defensive flange (2) intended to deform by dissipating energy under application of a crash force along the longitudinal axis, the first and second defensive flanges framing the electric battery along the transverse axis (Y).

3. Protective structure according to claim 2, further comprising a front plate (4) connecting the front edges (la,2a) of the first and second defense flanges.

4. Protective structure according to any one of claims 1 to 3, further comprising a liquid retention tray (5).

5. Protective structure according to any one of claims 1 to 4, wherein the protector (10) is a one-piece sheet metal manufactured by cutting and bending from a thick sheet blank, of a thickness between 2 mm and 2.5 mm.

6. Protective structure according to any one of claims 1 to 5, wherein a predetermined minimum distance is provided separating the positive and negative terminals (B+, B-) of the auxiliary battery from an element closest to the protector.

7. Protective structure according to any one of claims 1 to 6, wherein the four fixings secure both the protector and the retention tray on the support crossmember, and / or on a body element of the vehicle.

8. Protective structure according to any one of claims 1 to 7, wherein the upper connecting strip includes attachment elements (81,82) for fixing a fuse box (8).

9. A motor vehicle having a longitudinal axis (X), a transverse axis (Y) and a vertical axis (Z), preferably electric or hybrid, with a front overhang of less than 850 mm, the vehicle comprising an electric auxiliary battery (BAT) arranged in a front overhang area, the vehicle comprising a protective structure according to any one of claims 1 to 8.

10. Assembly comprising at least a first motor vehicle (MV) according to claim 9 and a second motor vehicle according to claim 9, the first motor vehicle being of the left-hand drive type and the second motor vehicle being of the right-hand drive type, characterized in that the position of the electric auxiliary battery is identical for the first and second vehicles.

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