WO2014140412A1

WO2014140412A1 - Base frame for an energy storage of a vehicle

Info

Publication number: WO2014140412A1
Application number: PCT/FI2013/050291
Authority: WO
Inventors: Lasse KOPRA; Jukka-Pekka Multasuo; Klaus RAUNELA; Jyri KYLÄ-KAILA
Original assignee: Valmet Automotive Oy
Priority date: 2013-03-14
Filing date: 2013-03-14
Publication date: 2014-09-18

Abstract

The present invention relates to base frame for an energy storage of a vehicle. The base frame (1) forms a solid structure onto which the energy storage (8) is mounted, said energy storage (8) containing battery cells with necessary supporting structures and auxiliary equipment for the same. The base frame is detachably fixed to the chassis frame or unit-body (6, 7) of the vehicle. The base frame (1) is formed of a light metal material by extrusion to a hollow structure comprising an upper layer (2a), a lower layer (3a) and number of partition walls (4) extending between the upper and lower layers (2a, 3a)so that the hollow space between said upper and lower layers (2a, 3a) is divided into cavities. The joint between the base frame (1) and the chassis frame or unit-body (6, 7) of the vehicle is rigid, so that when fixed to the vehicle the base frame forms a part and a stiffening structure of the chassis frame or unit-body (6, 7) of the vehicle.

Description

BASE FRAME FOR AN ENERGY STORAGE OF A VEHICLE

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a base frame for an energy storage of a vehicle, said base frame forming a solid structure onto which the energy storage is mounted, said energy storage containing battery cells with necessary structures and equipment for the same, whereby the base frame is detachably fixed to chassis frame or unit-body of the vehicle.

BACKGROUND OF THE INVENTION It is common that battery packs of electric vehicles are large and heavy causing significant challenges in the structural design of such vehicles. It is often necessary to provide the load-bearing structures with considerable reinforcements or corresponding support structures to get those rigid enough. This makes the load-bearing structures more complicated and increases the amount of components of the same. The bodies of electric vehicles become considerably more complicated and heavier than e.g. those of vehicles provided with combustion engines. Also the large size of traction batteries causes challenges because normally any de^¬ formation is not acceptable in them in an event of a collision. A deformation of a battery cell can cause an uncontrolled discharge of the battery which may lead to e.g. a fire or even explosion.

In prior art applications of electric automobiles the deformation areas and rigid structures relating to crash safety are designed and formed in the body structure while the battery pack is mainly considered as a self-supporting component separate from the body structure of the vehicle. A self-supporting battery pack causes a considerable increase in the amount of components and weight. Increase in the weight of the battery pack causes a mass concentration in the vehicle and therefore also other supporting structures of the vehicle must be reinforced. This causes even greater increase in the weight of the vehicle.

One example of prior art energy storage constructions is shown in publication EP 2070754 Al . This publication describes a battery pack for an electric vehicle which battery pack is self-supporting comprising a steel frame of sheet metal structure made of multiple components. Beam-like steel structures are passing through the lower part of the steel frame and the bat^¬ tery pack is secured to the car body through the beam ends so that the battery pack forms only limited sup^¬ port for the body.

A further prior art energy storage construction is disclosed in publication WO 2011/154790 Al . The bat- tery pack according to this publication is formed and mounted in a frame comprising sheet metal components and cast metal parts. The support given by the secur^¬ ing of the battery pack to the car body is very limited and therefore a special protective housing is made in the body, said housing protecting the battery pack against deformation. A separate battery pack of this kind which is not integrated in the body struc- ture of the vehicle causes a considerable extra weight and more complex constructions in all support and pro^¬ tective structures of the vehicle. SUMMARY OF THE INVENTION

The object of the present invention is to provide a support structure for an energy storage of a vehicle, e.g. an electric or hybrid vehicle, with a unit-body or frame based construction, that avoids the problem relating to prior art technique. The object of the in^¬ vention is achieved by the base frame for an energy storage of a vehicle characterized in that the base frame comprises a base profile formed of a light metal material by extrusion to a fixed cross-sectional hol^¬ low cavity profile, and that the joint between the base frame and the chassis frame or unit-body of the vehicle is rigid, so that when fixed to the vehicle the base frame forms a part and a stiffening structure of the chassis frame or unit-body of the vehicle.

The base frame can preferably be provided with flanges of the same and uniform material with the base pro^¬ file, in which case the base frame is arranged to be fixed to the chassis frame or unit-body of the vehicle through said flanges.

The base frame can further be provided with side mem^¬ bers extending upwards above the upper surface of the upper layer and on both sides of the base profile in the longitudinal direction of the base profile, where^¬ by the energy storage is situated on the base profile between the side members. A lid can be provided on the side members, so that said lid together with the side members form a cover for the energy storage. The side members and the lid can be formed separately from the base profile. In such case the side members and the lid can be formed together to form a complete detachable cover for the energy storage. The side members and the lid may also be manufactured of a material different from the material of the base profile. The material used for manufacturing of the side members and the lid may be composite. The base profile together with the side members and the lid can be made as a uniform tube-like structure in the manufacturing process.

The light metal material used for manufacturing of the base frame is preferably aluminium alloy.

When the base frame is fixed to the body of the vehi^¬ cle, it forms a rigid structure and load paths for im^¬ pact forces occurring in an event of a collision, pre- venting deformation of the passenger compartment and energy storage. Crumble zones for controlled defor^¬ mation can be formed in the base frame to absorb im^¬ pact forces occurring in an event of collision. Several advantages over prior art are attainable by the present invention. In the invention the base frame of the energy storage is made of an extruded profile of aluminium alloy. By extrusion process it is possi- ble to produce a very light, rigid, simple and cheap structure suitable for serial production. Energy source, e.g. battery modules and their supporting, connecting and cooling structures are mounted on the base frame and said base frame is fixed to the chassis frame or unit-body of the vehicle from which the base frame however can be demounted with the energy storage when necessary. The extruded aluminium alloy profile works as a stiffening element for the chassis frame or unit-body of the vehicle and as a base structure for the energy storage. It is possible to integrate even into one single aluminium alloy profile a great amount of functional properties, variation of wall structures with different thicknesses as well as different shapes and connection possibilities in accordance with needs. In a completed structure the amount of components and connections is considerably smaller than e.g. with sheet metal structure, because it is possible to inte^¬ grate more operational features in a single profile compared with a piece of sheet metal.

Further advantages, characteristic features and embod^¬ iments of the invention will come out in more detail in the following description of the invention, in which the invention is described with reference to the figures in the accompanying drawings. However, it is to be emphasized that the purpose of the drawings is to illustrate the embodiments of the invention by sim^¬ plified examples only.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross section of the first em^¬ bodiment of base frame according to the present inven^¬ tion. Figs. 2 - 4 describe alternative embodiments of the present invention.

Figs. 5 - 7 describe variations of the arrangement of the base frame in a vehicle in isometric projection.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In Fig. 1 the base frame according to the invention is denoted with the reference numeral 1. The base profile la of the base frame 1 is formed of a light metal by extrusion. The material of the base frame is prefera^¬ bly aluminium alloy. The base profile la is a hollow structure comprising two adjacent and opposite surface layers, namely an upper layer 2a having an upper sur- face 2 and a lower layer 3a having a lower surface 3 and number of partition walls 4 between said upper and lower surfaces 2 and 3. The hollow space between said opposite surface layers, i.e. between the upper and lower layers 2a and 3a is divided into cavities 5 by the partition walls 4. As mentioned above the base profile la is manufactured by extrusion, so that the partition walls 4 as well as the cavities 5 extend in the longitudinal direction of the base profile la. In the transverse direction the angle in which the parti- tion walls 4 join to the upper and lower layers 2a and 3a may vary depending on the desired properties of the base frame. Also the spaces between the adjacent par- tition walls 4 may vary according to the desired prop^¬ erties .

The energy storage is denoted with reference numeral 8 in Fig. 1 and as said Fig. 1 shows the energy storage 8 is mounted on the upper surface 2 of the base pro^¬ file la. It is not shown in the drawings but the ener^¬ gy storage 8 contains battery cells and necessary aux^¬ iliary equipment, electrical connections, insulation layers, supporting structures and protective shell structures. The base frame 1 is detachably fixed to the chassis frame or unit-body 6, 7 of the vehicle so that the joint between the base frame 1 and the chas^¬ sis frame or unit-body 6, 7 of the vehicle is rigid. When the base frame 1 is fixed to the vehicle it forms a part of the chassis frame or unit-body 6, 7 of the vehicle supporting the frame or unit-body considera^¬ bly. Further, deviating from the structure shown in Fig. 1 the upper and lower surfaces 2 and 3 of the profile structure are not necessarily planar but ac^¬ cording to the desired shape and design they can be made to form surfaces which are curved at least in one direction and/or they can extend stepwise to more than just one level.

Alternative embodiments of the present invention are shown in Figs. 2 - 4. In Fig. 2 the base frame is de^¬ noted with reference numeral 11. The base frame 11 of this embodiment is in other parts substantially iden- tical with the embodiment of Fig. 1 with the exception that the base frame 11 of Fig. 2 is provided with flanges 12. Also in this embodiment the shape of the profile structure can differ from the illustrated one in the same way as described above in connection with Fig. 1. The base frame 11 can be easily fixed to the frame or body 6, 7 of the vehicle through these flang- es 12, which is the main purpose of said flanges 12. In a similar way as in the embodiment of Fig. 1 the base frame 11 comprises a base profile 11a. The flang^¬ es 12 are a uniform part of the base profile 11a and they are formed in the extrusion process. The flanges 12 extend in the longitudinal direction of the base profile 11a and in the embodiment shown in Fig. 2 they are formed of rigid material on the level of the lower surface 3 of the base frame 11 as extensions of said lower surface 3. In this way it is easy to assemble the base frame 11 to the chassis frame or unit-body of the vehicle from below and fix it to said frame or body through the flanges 12.

Further, differing from the structure shown in Fig. 2 the flanges 12 can be constructed and formed as exten^¬ sions of the base profile 11a, so that the flanges comprise upper and lower surfaces 2, 3 connected with each other by partition walls 4. So the structure of the flanges 12 can be similar with that of the rest of the base profile 11a. In this kind of construction the mutual distance between the upper and lower surfaces 2, 3 of the flanges 12 can be different from said dis^¬ tance in the base frame 11. It can be e.g. smaller to get the thickness of the flanges suitable. The flanges 12 can also be arranged on the level of the upper sur^¬ face 2 instead of the lower surface 3 or anywhere be^¬ tween the upper and lower surfaces. The flanges can also be constructed so that they extend either above the upper surface 2 or below the lower surface 3. It may further be noted that flanges can also be arranged in the transverse direction at the ends of the base frame 11.

Fig. 3 shows a further modified embodiment of the in^¬ ventive base frame which is generally denoted with reference numeral 21. In addition to base frame 11 of Fig. 2 in the embodiment set forth in Fig. 3 the base frame 21 is provided with side walls or side members 22 extending obliquely upwards above the upper surface

2 in the longitudinal direction of the base profile 21a of the base frame 21. The energy storage 8 is sit- uated on the upper surface 2 of the base profile 21a between the side members 22. The side members 22 may consist of a similar hollow structure as the base pro^¬ file 21a, comprising side layers 22a, 22b, partition walls 24 between them and cavities 25 between the side layers 22a, 22b and the partition walls 24. The side members 22 can be made of the same material and by a similar process as the base profile 21a, i.e. by ex^¬ trusion. The side members 22 may be produced separate^¬ ly from the manufacture of the base profile 21a but, however, it is not excluded to produce the base pro^¬ file 21a and the side members 22 simultaneously. Fig.

3 shows further that a lid 23 may be mounted on the top of the side members 22 to cover the energy storage 8. Said lid 23 may be manufactured of the same materi- al and by the similar process as the side members 22. The structure disclosed in Fig. 3 can be modified in many ways. The lid 23 may be made in a separate pro^¬ cess and of a material different from the material of the base profile 21a. One possibility is to make the lid 23 of a composite. The lid 23 may also be made uniformly with the side members 22 so that they to^¬ gether form a complete cover or covering part for the energy storage 8 to be attached to the base profile 21a. According to one alternative embodiment the side member 22, 23 to be attached to the base profile 21a may comprise a covering part for an opening. It may also comprise a covering part to cover the energy storage 8 from below—in which case the opening would be in the base profile 21a

Fig. 4 discloses an embodiment of the invention in which the base frame 31 with an extruded base profile 31a with the side members 32 and the lid 33 is made as a uniform tube-like structure in the manufacturing process. The tube-like structure of this kind, as the embodiments described by Fig. 3, can be used e.g. as a centre tunnel of a vehicle to provide torsional rigid^¬ ity to the unit-body of the vehicle and at the same time to provide an excellent safe space for the energy store 8 containing the battery cells. In Fig. 4 the side members 32 are shown extending rectangularly upwards from the base profile 31a, but it is to be un^¬ derstood that the direction of the side members 32 is not an issue of the invention but said direction of extension depends on the shape of the energy storage 8 and the needs of the body of the vehicle. Figs. 5 - 7 show some variations of the arrangement of the base frame in a vehicle in isometric projection. The vehicle itself is not shown in these drawings. In Fig. 5 the base profile 41a is arranged in the vehicle in the longitudinal direction L of said vehicle. The base frame 41a is mounted in the vehicle as already explained in connection with Figs. 1 - 4 so that the base frame 41a forms a part of the vehicle chassis frame or unit-body. The base profile 41a alone forms the base frame on which the energy storage e.g. bat^¬ tery modules, necessary supporting structures and aux^¬ iliary equipment as well as the shell structure for the batteries are mounted. In Fig. 6 the base frame is comprised of two base profiles 41a, 41b, first one 41a of which is arranged in a similar way as in Fig. 5, in the longitudinal direction L of the vehicle. The se^¬ cond base profile 41b is arranged transversely to the first base profile 41a and fixed thereto to form a uniform base frame of an energy storage. Further in Fig. 7 the arrangement comprises a longitudinally ar^¬ ranged base profile 41a and two transverse base pro^¬ files 41b. The base profiles 41a, 41b and the base frame formed thereof work as a stiffening element-s- for the unit-body and non-deforming structures for the passenger compartment of the vehicle. In an event of side collision, the profiles 41a, 41b act as rigid load paths for forces impact Fi, F₂. It is also possi^¬ ble to design deformation areas when necessary in the base frame made of aluminium alloy profile to absorb forces occurring in an event of collision. The profile creates good and meticulous attachment possibilities for structures to be fixed thereto. Above, the invention has been described by way of ex^¬ amples with reference to the exemplifying embodiments illustrated in the accompanying drawings. The inven- tion is, however, not confined to the exemplifying embodiments shown in the drawings alone, but the inven^¬ tion may vary within the scope of the inventive idea defined in the accompanying claims.

Claims

1. Base frame for an energy storage of a vehicle, said base frame (1, 11, 21, 31) forming a solid structure onto which the energy storage (8) is mounted, said en^¬ ergy storage (8) containing battery cells with necessary structures and equipment for the same, whereby the base frame is detachably fixed to the chassis frame or unit-body (6, 7) of the vehicle, c h a r a c - teri zed in

-that the base frame (1, 11, 21, 31) comprises a base profile (la, 11a, 21a, 31a) formed of a light metal material by extrusion to a fixed cross-sectional hollow cavity profile, and

-that the joint between the base frame (1, 11, 21,

31) and the chassis frame or unit-body (6, 7) of the vehicle is rigid, so that when fixed to the vehicle the base frame forms a part and a stiffening structure of the chassis frame or unit-body (6, 7) of the vehi- cle.

2. Base frame for an energy storage of a vehicle as claimed in claim 1, characteri zed in that the base frame (11, 21, 31) is provided with flanges (12) of the same and uniform material with the base profile (11a, 21a, 31a), whereby the base frame (11, 21, 31) is arranged to be fixed to the chassis frame or unit- body (6, 7) of the vehicle through said flanges (12) .

3. Base frame for an energy storage of a vehicle as claimed in claim 1 or 2, characteri zed in that the base frame (1, 11, 21, 31) is further provided with side members (22, 32) extending upwards above the upper surface (2) of the upper layer (2a) and on both sides of the base profile (la, 11a, 21a, 31a) in the longitudinal direction of the base profile (la, 11a, 21a, 31a), whereby the energy storage (8) is situated on the base profile (la, 11a, 21a, 31a) between the side members (22, 32) .

4. Base frame for an energy storage of a vehicle as claimed in claim 3, characteri zed in that a lid (23) is provided on the side members (22, 32), so that said lid (23) together with the side members (22, 32) form a cover for the energy storage (8) .

5. Base frame for an energy storage of a vehicle as claimed in claim 3 or 4, characteri zed in that the side members (22, 32) and the lid (23) are formed separately from the base profile (la, 11a, 21a, 31a) .

6. Base frame for an energy storage of a vehicle as claimed in claim 5, characteri zed in that the side members (22, 32) and the lid (23) are formed to^¬ gether to form a complete detachable cover for the en^¬ ergy storage ( 8 ) .

7. Base frame for an energy storage of a vehicle as claimed in claim 5 or 6, characteri zed in that the side members (22, 32) and the lid (23) are manu^¬ factured of a material different from the material of the base profile (la, 11a, 21a, 31a) .

8. Base frame for an energy storage of a vehicle as claimed in claim 7, characteri zed in that the material used for manufacturing of the side members (22, 32) and the lid (23) is composite.

9. Base frame for an energy storage of a vehicle as claimed in claim 3 or 4, characteri zed in that the base profile (31a) together with the side members (32) and the lid (33) are made as a uniform tube-like structure in the manufacturing process.

10. Base frame for an energy storage of a vehicle as claimed in any of the preceding claims, charac^¬ teri zed in that the light metal material used for manufacturing of the base frame (1, 11, 21, 31) is al^¬ uminium alloy.

11. Base frame for an energy storage of a vehicle as claimed in any of the preceding claims, charac^¬ teri zed in that when the base frame (1, 11, 21, 31) is fixed to the body of the vehicle, it forms a rigid structure and load paths for impact forces (Fi, F₂) occurring in an event of a collision, preventing deformation of the passenger compartment and energy storage .

12. Base frame for an energy storage of a vehicle as claimed in any of the preceding claims, charac^¬ teri zed in that crumble zones for controlled de^¬ formation are formed in the base frame (1, 11, 21, 31) to absorb impact forces (Fi, F₂) occurring in an event of a collision.