Battery pack

Field of the invention

0001The invention relates to a battery pack for electric vehicles or vehicles with an electrohybrid drive. Recently, interest has been directed to vehicles driven by the driving force of an electric motor, for example, hybrid vehicles, fuel cell vehicles, electric vehicles, etc. Such vehicles are generally less polluting than solely combustion engines driven by internal combustion engines. These vehicles are equipped with a battery, a capacitor or the like for storing electrical energy to be supplied to one or more electric motors.

0002The term "battery" in the sense of the present application is to be understood as an electrical energy storage device, which can be both rechargeable and non-rechargeable. In this respect, the application text does not distinguish between the terms "accumulator" and "battery" on the other hand. The term "battery" in the sense of the application can also be understood as a capacitor.

0003Batteries as electrochemical voltage sources often comprise a series connection and / or parallel connection of a plurality of battery modules which are formed, if appropriate, by a series connection and / or parallel connection of a plurality of battery cells. The battery cells comprise two electrodes separated by a separator and a generally liquid or gel-like electrolyte.

0004For example, modern lithium-ion batteries or lithium-metal batteries are hermetically encapsulated, since lithium is a highly reactive metal and the components of a lithium-ion battery are easily combustible. Such battery cells are sensitive to mechanical impairments, which can lead, for example, to internal short circuits. Lithium-ion batteries or lithium-metal batteries can ignite by internal short-circuit and in contact with air. Because of their extraordinarily high storage capacity and relatively low space requirements, lithium-ion-based battery cells are particularly suitable for the manufacture of batteries for electric vehicles.

0005It is easily conceivable for batteries to be provided for electric vehicles which have a comparatively high storage capacity and a relatively large clamping voltage. In particular for the automotive industry, for example for full-electric vehicles, the battery cells must be correspondingly large and have a high absolute weight because of the high specific weight of the electrodes. As already mentioned above, lithium-ion or lithium-metal-based battery cells are, for example, mechanically sensitive so that special measures must be taken when installing in a motor vehicle in order to protect the battery cells from mechanical impairment. In a modern passenger car, acceleration forces from two to three times the acceleration of gravity in any space axis are to be expected during normal operating cycles. Such forces act on the vehicle in acceleration, deceleration, cornering and overcoming unevenness. In addition, it is absolutely necessary to secure a battery installed in a motor vehicle against impact-induced mechanical effects and against impact-induced acceleration forces. Furthermore, the batteries and thus the battery cells and their connections are exposed to vehicle-induced vibrations.

0006Finally, the battery heats up both during charging and discharging cycles. Depending on the solar irradiation, temperatures of up to 60 ° C. can prevail in a passenger compartment of a passenger car without the thermal effects of the drive and a battery, which is also important when designing a vehicle battery.

State of the art

0007A large battery pack for a hybrid locomotive, which is designed in such a way that it allows predominantly free convective cooling of the individual battery cells, is known, for example, from the <patcit id="pcit0001" dnum="WO2007047809A2"><text>WO 2007/047809 A2</text></patcit> known. This battery pack consists in a known manner of individual modules, which are arranged in drawers of a shelf system which is designed as a load-bearing construction. The individual modules each comprise two cells, which are fixed in the drawers at a distance from one another. The compartments are designed in such a way that the individual modules are thermally separated from one another, the cells being arranged at a distance from one another in such a way that at least one convection channel is formed, which allows an upward heat removal. The entire shelf arrangement is supported by horizontal and vertical insulators as shock absorbers. These shock absorbers enable a limited mobility of the entire arrangement, which is surrounded by a ventilated or mechanically ventilatable hood.

0008In the <patcit id="pcit0002" dnum="WO2007047809A2"><text>WO 2007/047809 A2</text></patcit> Described arrangement which weighs on the order of magnitude between 15 and 30 t may indeed be suitable for use on an electric motor vehicle or an electric motor and in this connection provide an optimum protection for the batteries, for use in a passenger car is such an arrangement In particular also for reasons of space.

0009A vibration-proof arrangement of individual cells or modules of a battery that is free of vibrations for reasons of convective heat dissipation is not feasible in the narrow space of a car.

0010In the <patcit id="pcit0003" dnum="WO2007102670A1"><text>WO 2007/102670 A1</text></patcit> A battery module is described which contains a battery cell stack with a plurality of battery modules arranged directly next to one another in a row and which are electrically connected to one another and which are respectively fixedly mounted on a common frame via coupling parts and supporting elements.

task

0011Precisely modern lithium-ion or lithium-metal batteries are characterized by a high energy density which makes them suitable for use in cars.

0012The invention is therefore based on the object of providing a battery pack for electric vehicles or vehicles with an electric drive which permits a sufficient protection against mechanical impairment of the battery cells due to vibrations and approximately accelerating forces which are effective under optimal space utilization of a given installation space in a passenger car. Furthermore, the battery pack according to the invention is also designed in such a way that thermal overloading of the battery cells is largely avoided.

solution

0013The object is achieved by a battery pack for electric vehicles or vehicles with an electrohybrid drive, comprising a battery housing as well as self-contained battery cells arranged inside the battery housing, which are electrically connected to one another in order to achieve a desired terminal voltage And in each case form cell modules, the cell modules being arranged in each case on the fastening elements, which penetrate the battery housing, which are designed as spacers between the cell modules and form a bearing unit with the battery housing.

0014The battery pack according to the invention is characterized in particular by a very compact and space-saving construction. In particular, in that the spacers of the cell modules with the battery housing form a load-bearing unit, it is ensured that all forces occurring in the installation situation in the vehicle are transmitted from the individual cells to the battery housing. This type of force transmission ensures that no vibrations of the cells occur or that relative movements occur between the cells and the battery housing.

0015Expediently, at least some of the fastening elements are designed as profiled rods, which at least two of the enclosing walls of the battery housing are supported against one another.

0016In a preferred variant of the battery pack according to the invention, it is provided that the mounting frames of the cell modules form part of the supporting unit, whereby a stability gain without additional material use is achieved. The individual mounting frames keep the cells arranged in them apart so that the cells are essentially free of forces during acceleration or deceleration of the vehicle and the occurring forces are introduced into the fastening elements via the fastening frames into the fastening elements and from the fastening elements into the battery housing. The battery housing is expediently fastened to a corresponding receptacle in the motor vehicle.

0017Preferably, the cells are resiliently mounted within a mounting frame at least in the direction of a spatial axis. These can, for example, be suspended in the fastening frame with the interposition of elastomer strips, felt strips, strips of thermoplastic or the like. The construction according to the invention permits a limited mobility of the individual cells without the cells having to absorb forces of neighboring cells.

0018The cell modules are suitably interconnected via electrical connectors. The connectors can, for example, consist of light metal. In a variant of the battery pack according to the invention, it is provided that the connectors are made of aluminum. This ensures a particularly favorable heat emission to the environment.

0019In a particularly advantageous embodiment of the battery pack according to the invention, the inventors are designed as rectangular plates with a surface / volume ratio [m²/ M³], 0.3 to 2.0. This design has proved to be particularly favorable with regard to heat emission.

0020In order to optimize the space utilization of the battery housing, the cell modules can be arranged in rows in a plurality of rows within the battery housing.

0021For thermal reasons, it is particularly advantageous for the row-by-row arrangement of the cell modules to be selected such that interspaces between the cells of adjacent rows are aligned with one another or communicate with each other. In this way, a favorable air flow through the battery housing can be achieved.

0022In a variant of the battery pack according to the invention, it is provided that the fastening elements of a plurality of cell modules arranged one above the other and / or next to one another are connected to form a grid structure.

0023It is expedient if the battery housing has at least one ventilation opening and one ventilation opening, which permit both a pressure-induced and a convective aeration of the battery housing. For this purpose, the battery housing can, for example, be connected with the ventilation opening to an air duct of the motor vehicle. When the motor vehicle is at a standstill, the air pressure-induced air flow due to driving dynamics is eliminated. In this case, a convective heat emission or a ventilation of the battery housing by means of an additional fan is considered.

0024The profile bars passing through the battery housing are expediently designed as T-profiles.

0025The battery cells are expediently designed as electrodes inserted into plastic films with separators arranged therebetween and a liquid electrolyte, these each having two flexible connecting lugs, which are connected to the connectors in such a way that no appreciable forces are introduced into the housing by a relative movement between the battery cells and the connectors Battery cells.

0026The separators provided in the battery cells can, for example, have a ceramic surface and consist of a flat, flexible substrate provided with a plurality of openings with a coating located on and in this substrate. The material of the substrate can consist of woven or non-woven, non-electrically conductive natural or polymer fibers. The coating may be a porous, electrically insulating, ceramic coating. The separators can be filled with an electrolyte composition which has a conducting salt and a basic component, the basic component having a proportion of greater than 50% by mass at least one ionic liquid which has a melting point below 100 ° C.

0027The electrodes and separators can each be welded in a pocket made of an aluminum polymer material. For example, each cell may have a capacity of about 40 amperes. The size of such a battery cell can be, for example, approximately 20 × 30 × 10 mm. Such a battery cell has a weight of 1 kg. A battery pack according to the invention may have between 100 and 200 such cells.

0028BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained below with reference to an exemplary embodiment illustrated with drawings.

Description of the figures

0029Show it:<ul><li><figref idrefs="f0001">FIG</figref> A perspective view of an opened battery housing with fastening elements arranged therein and cell modules arranged therein,</li><li><figref idrefs="f0002">FIG</figref> A perspective view of the cell modules arranged within the battery housing without the enclosing walls of the battery housing,</li><li><figref idrefs="f0003">FIGS</figref> and <figref idrefs="f0004">4</figref> Perspective views of the cell modules of the battery pack according to the invention,</li><li><figref idrefs="f0005">FIG</figref> A perspective view of the battery pack according to the invention with the battery housing closed, the ventilation openings being arranged on the side of the battery housing facing the viewer, and FIG</li><li><figref idrefs="f0006">FIG</figref> A rear view of the partially opened battery housing with cell modules arranged in rows.</li></ul>

0030An exemplary embodiment of the battery pack 1 according to the invention is shown in the drawings. The battery pack 1 comprises a battery housing 2 and battery cells 3 suspended in the battery housing 2, which are designed as an electrochemical voltage source based on lithium. Each battery cell 3 is designed as a lithium-ion battery or lithium-ion battery and comprises, as already mentioned above, two electrodes separated by a separator, which are welded together with an electrolyte into a plastic pocket. The battery cells 3 are designed as hermetically sealed battery cells 3 each with two connection lugs.

0031In each case two battery cells 3 are connected in parallel with one another, in each case two parallel-connected battery cells 3 are connected in series within a cell module 4.

0032The cell modules 4 are, for example, shown in FIGS <figref idrefs="f0003">FIGS</figref> and <figref idrefs="f0004">4</figref> Respectively. These cell modules 4 are located within the battery housing 2 as shown in FIG<figref idrefs="f0002">FIG</figref> Is arranged in rows and electrically connected in series. The connection of the cell modules 4 to one another is effected by connectors 5a, which are designed as aluminum plates which are rectangular in cross-section. Two battery cell pairs within a cell module 4 are connected in series with each other via the connectors 5b.

0033In the <figref idrefs="f0003">FIGS</figref> and <figref idrefs="f0004">4</figref> The cell modules 4 are each shown in perspective. As already mentioned above, each cell module 4 comprises four battery cells 3, which are suspended in a mounting frame 6. The mounting frame 6 comprises two front-side diaphragms 7 which are designed as stamped aluminum plates with a ventilation opening 8 as well as between these spacers 9 extending between the individual battery cells 3. The spacers 9 have a profile T-shaped in the cross-section and are designed as aluminum extrusion press profiles. How this<figref idrefs="f0003">FIGS</figref> and <figref idrefs="f0004">4</figref> The spacers 9, in each case six in number, are each screwed on their end faces with the diaphragms 7. The diaphragms 7 each comprise four fixing tubes 10 provided with holes, by means of which these can be secured in the mounting position.

0034In the following, reference is first made to the <figref idrefs="f0001">FIG</figref>. In<figref idrefs="f0001">FIG</figref> Parts of the battery housing 2 without the cell modules 4, which are also designed as a supporting part of the battery pack 1, are shown. The battery housing 2 is formed by a total of six enclosing walls 11, of which<figref idrefs="f0002">FIG</figref> Only two end walls 11 are shown. Between these enclosing walls 11 are also spacers 12 which extend through the battery housing 2 and support the surrounding walls 11 in such a way that they form a supporting unit together with the cell modules 4 and the enclosing walls 11. The spacers indicated with 12 are also designed as aluminum extrusion profiles with a T-shaped cross-section. As is also the case in<figref idrefs="f0001">FIG</figref> , The fastening tubes 10 of the diaphragms 7 of the fastening frames 6 forming the cell modules 4 are secured on the spacers 12 by means of screw connections.

0035In the <figref idrefs="f0001">FIGS</figref>, <figref idrefs="f0002">2</figref> and <figref idrefs="f0005">5</figref> The battery pack 1 according to the invention is shown in the mounting position in such a way that the front side faces the observer. For the purpose of reference, the<figref idrefs="f0001">FIG</figref> The longitudinal direction of the battery case 2 as the X direction, and the depth of the battery case 2 as the Z direction. As can be readily seen from the drawing, the spacers 12 acting as fastening elements extend within the battery housing 2 only in the direction of the Y axis and the Z axis, but not in the direction of the X axis. The stability in the direction of the X axis is generated by the cell modules 4 and their connection among themselves.

0036As also from the <figref idrefs="f0003">FIG</figref> , The cell modules 4 have a terminal plate 13 which receives the connectors 5a, 5b. The connection plate 13 is rigidly connected to the diaphragms 7. About the<figref idrefs="f0003">FIG</figref> , Two battery cells 3 of a cell module 4 are connected in series with each other. The connector 5a is screwed to sockets 14 of the connection plate 13. Each connection plate 13 comprises four such sockets. In the<figref idrefs="f0003">FIG</figref> Free sockets are used to receive the connectors 5b by means of which the cell modules are connected to one another in rows, that is, to a self-supporting bar. The arrangement of the cell modules 4 with respect to each other can, in particular,<figref idrefs="f0002">FIG</figref> .

0037The cell modules are each connected in 3 rows, namely a standing row 15 and two rows 16, to a battery.

0038It will be apparent to a person skilled in the art that the number of the cell modules 4 in a row, the number of rows as well as the arrangement of the rows 15, 16 depend on the assembly of the battery pack 1.

0039Reference numeral 17 denotes the connection terminals of the battery pack 1.

0040As already mentioned at the outset, the connectors 5a, 5b are designed as aluminum plates with a rectangular cross-section, which, in addition to their supporting function within the battery pack 1, also serve for the heat dissipation during operation.

0041Reference is now made to FIGS <figref idrefs="f0005">FIG</figref>, In which the battery pack 1 is shown completely with the battery housing 2 closed, in a front view.

0042The front surrounding wall 11 of the battery housing 2 is provided with two ventilation openings 18, which serve as inlet openings for a pressure-induced air flow. This air flow can be generated either by blower or by a flow due to the driving dynamics of the motor vehicle in which the battery pack 1 is installed. The air flow enters the battery housing 2 in the direction of the Z axis and penetrates the standing row 15 to cell modules 4. These cell modules 4 are arranged in such a way that the ventilation openings 8 of the diaphragms 7 of each cell module 4 face the incoming flow. As already mentioned above, the individual cells 3 are arranged at a distance from one another within the cell modules 4 by means of the spacers 9.

0043After the cooling air has passed through the standing row of the cell modules 4, the flow is circulated through the superimposed rows 16 in such a way that within the battery housing 2 a flow roller emerges which emerges from the air outlet denoted by reference numeral 19. This air outlet 19 also ensures the accessibility of the connection clamps 17.

0044In <figref idrefs="f0006">FIG</figref> The rear view of the battery housing 2 or of the battery pack 1 is shown, the rear surrounding wall being omitted for reasons of displayability.

0045As particularly from the <figref idrefs="f0005">FIG</figref> The enclosing walls 11 are screwed to the profile bars formed as spacers 12. Thus, the entire design achieves an extraordinarily high stability against acceleration forces acting in the installation situation, for example on the battery pack 1. As previously mentioned, the forces acting in the direction of the X-axis are absorbed by the mounting frames 6, which are supported in this direction, with each battery cell 3 being suspended within the mounting frame within certain limits. This is achieved by the fact that felt strips are arranged between the spacers 9 and the cells which hold the individual battery cell 3 essentially free of forces.

0046As already mentioned at the outset, the battery cells 3 are each designed as foliate pockets. The spacers 9 each have a profile T-shaped in the cross-section, each spacer 9 forming an angle whose leg length corresponds approximately to half the thickness of the battery cells 3. A battery cell 3 can thus be movably mounted between two upper and two lower spacers 9, with the interposition of a felt strip or film strip or elastomer strip, comparable to a window pane in a frame.

0047The connectors 5b provide both electrical and mechanical connection between the individual mounting frame 6 so that these connectors 5b can also form part of the supporting structure.

Reference list

0048<dl id="dl0001" compact="compact"><dt>1</dt><dd>Battery pack</dd><dt>2</dt><dd>Battery housing</dd><dt>3</dt><dd>Battery cells</dd><dt>4</dt><dd>Cell module</dd><dt>5a, 5b</dt><dd>Interconnects</dd><dt>6</dt><dd>Mounting frame</dd><dt>7</dt><dd>Screens</dd><dt>8th</dt><dd>Ventilation openings</dd><dt>9</dt><dd>Spacer</dd><dt>10</dt><dd>Mounting tubes</dd><dt>11</dt><dd>Enclosure walls</dd><dt>12</dt><dd>Spacer</dd><dt>13</dt><dd>Connection plate</dd><dt>14</dt><dd>base</dd><dt>15</dt><dd>Standing row of cell modules</dd><dt>16</dt><dd>Lying row of cell modules</dd><dt>17</dt><dd>Connection terminals</dd><dt>18</dt><dd>Ventilation openings</dd><dt>19</dt><dd>Air outlet</dd></dl>