DE102017209342B4 - Lower shell for a battery housing of a traction battery and traction battery - Google Patents

Abstract

Lower shell (100) for a battery housing of a traction battery, with:- a tray which has a base (110) and side walls (120, 130) surrounding this base (110); and- several longitudinal and transverse partition walls (140, 150) which divide the tray into individual compartments;characterized in thatthe partition walls (140, 150) are formed from fiber-plastic composite profiles and are connected to one another at the intersection points by means of node elements (160) made of aluminum,wherein the node elements (160) are designed with continuous insertion grooves (161) into which the partition walls (140, 150) are inserted, andwherein the node elements are also designed with through-holes (163) through which at least some of the node elements (160) are screwed to the base (110).

Description

The invention relates to a lower shell for a battery housing of a traction battery according to patent claim 1. The invention further relates to a traction battery for a motor vehicle according to the independent patent claim.

A traction or drive battery for an at least partially electrically powered motor vehicle (such as an electric car or a hybrid electric vehicle) usually has a sealed battery housing and battery cells or modules arranged inside this battery housing. Such battery housings are usually also designed to be crash-proof in order to be able to survive accidents (such as side and frontal crashes) without major damage to the battery cells or modules. Battery housings with a lower shell divided into several compartments have proven to be advantageous with regard to crash safety, among other things. Such battery housings are made from EN 10 2014 226 566 B3 and the EN 10 2016 209 853 A1 known.

From the nearest EN 10 2013 204 765 A1 A so-called storage cell assembly is known. The storage cell assembly has a housing in which storage cells are arranged, the housing having a left side wall, a right side wall, a front side wall, a rear side wall, a bottom wall and an upper wall. The side walls and the bottom wall form a kind of trough. The housing also has partitions that run parallel to the front side wall or the rear side wall and connect the bottom wall and the upper wall to one another. Furthermore, (at least) one longitudinal partition is provided, which runs between the front side wall and the rear side wall or between the upper wall and the bottom wall. The partitions stiffen the housing, and the trough is also divided into several compartments.

Regarding the state of the art, reference is also made to EN 10 2015 111 749 A1 , EN 10 2013 218 038 A1 and DE 203 12 800 U1 pointed out.

The invention is based on the object of specifying a further lower shell for a battery housing of a traction battery, which is divided into compartments and which is light, stable and easy to manufacture.

This object is achieved by a lower shell according to the invention with the features of patent claim 1. With the independent patent claim, the solution to the object also extends to a traction battery. Preferred further developments and embodiments of the invention arise analogously for both subject matters of the invention from the dependent patent claims, the following description of the invention and the drawing.

• - eine Wanne, die einen Boden und diesen Boden umgebende Seitenwände aufweist; und
• - mehrere längs- und querverlaufende Trennwände, welche die Wanne in einzelne Fächer zur Aufnahme der Batteriemodule unterteilen.

The lower shell according to the invention comprises:

• - a tank having a bottom and side walls surrounding said bottom; and
• - several longitudinal and transverse partitions which divide the tray into individual compartments to accommodate the battery modules.

According to the invention, the partition walls are formed from fiber-plastic composite profiles and are connected to one another at the intersection points by means of node elements made of an aluminum alloy, as explained in more detail below.

The longitudinal partition walls extend in the longitudinal direction of the vehicle with respect to an intended installation position of the battery housing in the motor vehicle and the transverse partition walls extend in the transverse direction of the vehicle. The longitudinal and transverse partition walls form a particularly stable and resilient framework within the tub, with the framework nodes being formed by aluminum node elements that connect the partition walls or individual partition wall elements to one another. Both the FKV or fiber-plastic composite profiles and the aluminum node elements have a high degree of rigidity and a high load-bearing capacity with a comparatively low weight, which gives the lower shell according to the invention a high degree of stability and very good accident or crash safety despite its low weight, which also meets high requirements. The lower shell according to the invention can therefore also be designed to be comparatively large, i.e. to accommodate many battery cells. In addition, new possibilities for optimizing installation space arise (e.g. additional space for battery cells and/or other structural measures can be released by making the partition walls thinner). The lower shell according to the invention can be manufactured quickly using comparatively simple assembly steps. Furthermore, the production of a lower shell according to the invention is comparatively inexpensive, i.e. it involves low costs.

Preferably, the partition walls are made of cut-to-length FKV pultrusion profiles and the node elements are made of cut-to-length or cut-to-size aluminum extruded profiles. The lower shell according to the invention can be constructed using many identical parts. It is economically advantageous to use both pultrusion profiles and extruded profiles as (if necessary also purchased) rods. ware is provided and the partition walls or node elements are created from them by simply cutting them to length with little waste. Both the FKV profiles and the aluminum profiles can be manufactured economically and at high production speeds in a continuous process (pultrusion process or extrusion process) and are characterized by a constant cross-section due to the manufacturing process. The pultrusion process can also integrate particularly high proportions of unidirectional fibers, which can then act in a load-path-optimized manner in the partition wall due to their good mechanical properties. Pultrusion profiles can absorb high crash loads due to a high fiber volume proportion and/or unidirectional fiber orientation, so that low wall thicknesses are possible and installation space is saved or freed up. Carbon fibers (CFRP) and/or electrically insulating glass fibers (GRP), for example, can be used as fiber material for the fiber-plastic composite. GRP profiles are particularly suitable for mixed construction (e.g. CFRP/GRP structures) due to their electrically insulating properties. Furthermore, copper strands and the like can be integrated, which improve electromagnetic compatibility (EMC).

Preferably, at least the longitudinal partition walls or at least the transverse partition walls are made of L-profiles (L-beams) or T-profiles (T-beams), i.e. the partition walls in question are (cut to length) L- or T-profiles. Preferably, these partition walls are arranged in the tub in such a way that they rest on the floor with their flanges. Such profiles also have a higher area moment of inertia, which improves mechanical stability. The partition walls can also be glued to the tub floor at their flanges. The bonding can also have a sealing function.

At least one partition wall can also be made from a double-web T-profile. This partition wall can rest on the floor with its flange and can optionally be glued to the floor. The partition wall, which is thus essentially double-walled, is particularly stable and resilient. Furthermore, cabling and/or electronic components, e.g. power electronics, or the like, can be arranged in the cavity between the two profile webs.

The partition walls are preferably attached to the side walls of the tub by means of connecting elements made of aluminum, which are in particular formed from cut-to-length extruded profiles.

According to the invention, the node elements are designed with continuous insertion grooves. Preferably, the connecting elements are also designed with continuous insertion grooves. The partition walls are inserted with their front ends into the continuous insertion grooves and are thereby positively connected to the respective node or connecting element. Optionally, they can also be glued and/or screwed. The glue can also have a sealing function.

In addition, according to the invention, the node elements are designed with through holes through which at least some of the node elements are screwed to the tub floor. At least some of the node elements can be designed with additional through holes through which screws or bolts for fastening the traction battery to the motor vehicle (e.g. to the underbody) can be passed.

The tub can be made in one piece or in multiple pieces. The tub is preferably made from aluminum components (sheet metal parts, profile parts, cast parts or the like) joined together. This means that the base and/or the side walls are preferably made of aluminum. The tub or individual components thereof can also be made of steel or FKV, for example. The tub has in particular a base with an integrated cooling device.

The traction battery claimed in the independent patent claim for a motor vehicle with electric or hybrid drive, which is in particular an HV battery (HV battery system), has a battery housing that includes a lower shell according to the invention. The battery housing preferably also includes an upper shell (cover) that is connected or can be connected to the lower shell. The traction battery can also include battery cells or modules arranged inside the battery housing, which are arranged in the compartments of the lower shell formed by the partition walls and are screwed to the floor, for example. The traction battery can also include contact elements or wiring and preferably also electronics or power electronics that are arranged on or in the battery housing.

• 1 zeigt eine erfindungsgemäße Unterschale einer Traktionsbatterie.
• 2 zeigt schematisch den Aufbau der Trennwände in der Unterschale aus 1.
• 3 zeigt mögliche Profilquerschnitte für die Trennwände in der Unterschale aus 1.
• 4 zeigt zwei einstückige Knotenelemente für die Verbindung von Trennwänden in der Unterschale aus 1.
• 5 zeigt die Verbindung zwischen Trennwänden in der Unterschale aus 1 mit einem der Knotenelemente aus 4.
• 6 zeigt die Verbindung zwischen Trennwänden in der Unterschale aus 1 mit dem anderen Knotenelemente aus 4.
• 7 zeigt zwei einstückige Verbindungselemente für die Befestigung der Trennwände an den Seitenwänden in der Unterschale aus 1.

Further features and advantages of the invention will become apparent from the following description with reference to the drawing.

• 1 shows a lower shell of a traction battery according to the invention.
• 2 shows schematically the structure of the partition walls in the lower shell made of 1 .
• 3 shows possible profile cross-sections for the partition walls in the lower shell 1 .
• 4 shows two one-piece node elements for connecting partition walls in the lower shell made of 1 .
• 5 shows the connection between partition walls in the lower shell of 1 with one of the node elements 4 .
• 6 shows the connection between partition walls in the lower shell of 1 with the other node elements from 4 .
• 7 shows two one-piece connecting elements for attaching the partition walls to the side walls in the lower shell made of 1 .

In the 1 The lower shell 100 shown belongs to a traction battery which is attached to the underbody of a motor vehicle. The forward direction of travel is indicated by FR. The lower shell 100 has a base (cooling base) 110 through which cooling medium can flow and side walls 120 and 130 surrounding this, which form a tub or a trough (ie a tub-like housing open at the top or a tub-like housing frame). The base 110 and the side walls 120 and 130 are preferably made of aluminum (aluminum tub). The base 110 can be made of several interconnected hollow profiles. Longitudinal (ie running in the direction of travel FR) partition walls 140 and transverse (ie running transverse to the direction of travel FR) partition walls 150 are arranged inside the tub. The partition walls 140 and 150, which are essentially only subjected to unidirectional stress, are made of fiber-plastic composite profiles. The partition walls 140 and 150 are connected to one another at their intersection points by means of node elements 160 and are fastened to the side walls 120 and 130 by means of connecting elements 170. The multidirectionally stressed node elements 160 and connecting elements 170 are made of aluminum, in particular of a ductile aluminum alloy. The partition walls 140 and 150 form a framework with individual compartments for accommodating battery modules. The partition walls 140 and 150 also form a bracing of the battery housing and serve to control load distribution in the event of a crash, in particular in the event of a frontal crash F1 or side crash F2. The partition walls 140 and 150 made of fiber-reinforced plastic composite material (FRP) also function as heat barriers between the compartments.

The partition walls 140 and 150 are cut to length FKV pultrusion profiles. For the 1 For the design option of a lower shell 100 shown, three different profile cross-sections are sufficient, as with the 2 T-profiles and double-webbed T-profiles are used for the transverse partition walls 150. Possible profile cross-sections, which are designed as solid, hollow and multi-chamber hollow profiles, are shown in the 3 The profiles have a web 151 and a flange or belt 152. 3d shows a T-profile with two parallel webs (double web) 151a/151b. The transverse partition walls 150 extend over the entire width of the tub, ie from one longitudinal side wall 120 to the opposite longitudinal side wall 120. Between them, partition wall elements 140 with a rectangular profile are arranged in the longitudinal or travel direction FR. In principle, however, T-profiles can also be used for this, such as in 3 shown. Analogously, the longitudinal partition walls 140 can be continuous and the transverse partition walls 150 can be formed from individual partition wall elements.

4 shows two possible designs for node elements 160. The node elements 160 are designed with continuous insertion or fastening grooves 161 and through holes 163. 7 shows two possible designs for connecting elements 170, which are also designed with continuous insertion or fastening grooves 171. The node elements 160 and connecting elements 170 are extruded aluminum profiles cut to the appropriate length. The node elements 160 and connecting elements 170 can also be cast parts (e.g. aluminum die-cast parts).

The production of the 1 The lower shell 100 shown can be carried out as follows (the sequence is variable). The partition walls or partition wall elements 140 and 150 are 2 shown, ie cut to the appropriate length. In the transverse partition wall elements 150, slots 153 are also milled or sawn into the webs 151, which end above the flanges or belts 152. The node elements 160 are inserted into these slots 153, which are designed with complementary insertion grooves 161 (see 4 ). The connection (see 5 and 6 ) is carried out by clamping, gluing and/or screwing. The connection to the tub floor 110 is made via the lower flanges or straps 152, which are preferably glued to the tub floor 110 for this purpose. The longitudinal partition wall elements 140 can then be inserted by inserting them from above into the still free insertion grooves 161 of the node elements 160 and securing them by clamping, gluing and/or screwing. The connection to the side walls 120 and 130 is made via the connecting elements (T-node elements) 170, for which the partition walls or partition wall elements 140 and 150 are inserted into the insertion grooves 171 and secured by clamping, gluing and/or screwing. The connecting elements 170 can be glued or welded to the side walls 120 and 130 on their rear surfaces 175. In principle, the connecting elements 170 can also be molded onto the side walls 120 and 130.

The individual components of the lower shell 100 form a modular plug-in system, which advantageously only allows one direction of assembly (from above), which is particularly advantageous with regard to automated production or assembly. Furthermore, there is the possibility of easy adaptation to all possible battery sizes. Special corrosion protection between the FKV partition walls and the aluminum node elements is not required, since the interior of the battery housing is a dry area. To increase safety, the FKV profiles can consist of carbon fibers embedded in glass fibers on the surface or completely (i.e. carbon fibers on the inside and glass fibers on the outside).

5 shows in a perspective view a connection between a transverse partition wall 150 and a longitudinal partition wall 140 by the 4a shown node element 160. The node element 160 has a through hole 163 through which the node element 160 can be screwed to the floor 110. Since the node element 160 sits on the flange or belt 152 of the partition wall profile 150, the partition wall 150 is pressed against the floor 110 and additionally fixed when the node element 160 is screwed on. The node element 160 can also be glued to the floor 110 at its flange 152. The cross profile 150 is thus very well secured against buckling, for example when a high load F2 (see 1 ) on the long side of the battery casing.

6 shows in a perspective view a connection between a transverse double-walled partition wall 150, which is formed from a double-webbed profile (see 3d ), and a longitudinal partition wall 140 through the 4b shown node element 160. The node element 160 has webs or middle webs 162 which engage in a form-fitting manner in the cavity 154 between the two webs 151a and 152b. In one of these webs 162, a further through-hole 164 is formed offset from the center, through which the traction battery can also be attached to the underbody of a motor vehicle (ie the battery housing is screwed through) in order to prevent sagging. In the event of a crash (including from below), such additional screwing points can also be used to divert part of the crash energy via the node elements 160 into the vehicle body. The screwing can, for example, extend to the seat rail, which is thus integrated into the force connection. In the cavity 154 between the surface-parallel webs 151a and 151b, wiring and/or electronic components can be accommodated in a space-saving manner.

The holes 163 and 164 in the node elements 160 can also be used to attach an upper shell or a cover and/or an underrun protection. The upper shell can be made of steel, for example, in particular a ductile steel material, which is advantageous for electromagnetic shielding and improves load distribution in the event of a crash. The same applies to an underrun protection optionally arranged under the floor 110.

This in 7a The connecting or end connecting element 170 shown is for fastening the 5 shown partition walls 140 and 150 are provided on the longitudinal and transverse side walls 120 and 130. The 7b The connecting or end connecting element 170 shown is for fastening the 6 shown double-walled partition 150 is provided on the longitudinal side walls 120 and has analogous to the node element 160 of the 4b a bridge or central bridge 172.

List of reference symbols

100

Bottom shell

110

Floor

120

Side wall

130

Side wall

140

partition wall

150

partition wall

151

web

151a

web

151b

web

152

Flange (belt)

153

Slot (notch)

154

cavity

160

Node element

161

Groove

162

web

163

drilling

164

drilling

170

Connecting element (T-junction element)

171

Groove

172

web

175

Back surface

FR

Direction of travel

F1

Frontal crash

F2

Side crash

Claims (10)

Lower shell (100) for a battery housing of a traction battery, with: - a tray which has a base (110) and side walls (120, 130) surrounding this base (110); and - several longitudinal and transverse partition walls (140, 150) which divide the tray into individual compartments; characterized in that the partition walls (140, 150) are formed from fiber-plastic composite profiles and are connected to one another at the intersection points by means of node elements (160) made of aluminum, wherein the node elements (160) are designed with continuous insertion grooves (161) into which the partition walls (140, 150) are inserted, and wherein the node elements are also designed with through holes (163) through which at least some of the node elements (160) are screwed to the base (110). Lower shell (100) after Claim 1 , characterized in that the partition walls (140, 150) are formed from cut-to-length pultrusion profiles and the node elements (160) are formed from cut-to-length extruded profiles. Lower shell (100) after Claim 1 or 2 , characterized in that at least the longitudinal partition walls (140) or at least the transverse partition walls (150) are formed from L-profiles or T-profiles and are supported by their flanges (152) on the floor (110). Lower shell (100) according to one of the preceding claims, characterized in that at least one partition wall (150) is formed from a double-web T-profile (151 a/151 b) and is supported by its flange (152) on the floor (110), wherein cabling and/or electronic components are arranged in the cavity (154) between the two webs (151a, 151b). Lower shell (100) according to one of the preceding claims, characterized in that the partition walls (140, 150) are fastened to the side walls (120, 130) by means of connecting elements (170) made of aluminum. Lower shell (100) after Claim 5 , characterized in that the connecting elements (170) are formed from cut-to-length extruded profiles. Lower shell (100) after Claim 5 or 6 , characterized in that the connecting elements (170) are formed with continuous insertion grooves (171) into which the partition walls (140, 150) are inserted. Lower shell (100) according to one of the preceding claims, characterized in that at least some of the node elements (160) are formed with additional through holes (164) through which screws or bolts can be passed for fastening the traction battery. Lower shell (100) according to one of the preceding claims, characterized in that the bottom (110) and the side walls (120, 130) are made of aluminum. Traction battery for a motor vehicle, with a battery housing having a lower shell (100) according to one of the preceding claims.

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