The invention relates to a battery, especially a high voltage lithium ion battery or nickel metal hydride battery for a vehicle with hybrid drive or a fuel cell vehicle.
According to the state of the art, heat generated in the cells of lithium ion batteries (e.g., for hybrid drives or fuel cell vehicles) during charging and discharging must be diverted by a cooling operation. Due to the maximum allowable cell temperature of about 50° C., cooling is provided via the air conditioning circuit of the vehicle.
According to the state of the art, batteries are known where cells are cooled from the base by a cooling plate through which a coolant flows. The heat is conducted through separate heat conducting bars in the longitudinal direction of the cell. So as to conduct heat from the cells to the cooling plate, heat conducting bars of aluminum are provided between the cells, which bars are anchored in the cooling plate and divert the heat in the longitudinal direction of the cells. However, such a cooling plate provided with both heat conducting bars and also a covering sheet is elaborate and expensive.
The cells are thermally coupled to the heat conducting bars by a casting compound, with which the cell assembly is filled. The casting compound provides electrical insulation, and also fixes the cells in the cell assembly. The casting compound further equalizes gaps due to tolerance between the components of the cell assembly. Epoxy resin, polyurethane or silicone are for example used as casting compound. The casting compound thus has only a relatively low mechanical stability compared to the other components of the cell assembly.
A jacket-like sheet, which is also placed on the cooling plate, encloses the cells laterally, serves for heat diversion, and acts as a mold for the casting compound that fills the spaces between cells and heat conducting bars. The entire cell block is surrounded with the covering sheet and is cast by means of a heat-conductive casting compound. The covering sheet thereby simultaneously forms the casting mold.
After the casting, the so-called cell block or cell assembly forms a massive construction which is secured in the battery housing. After the installation of the interior of the battery, the housing cover is secured by screwing, riveting or welding. The housing of a battery thus typically comprises a base, a sidewall and a cover.
For connecting the electrical connector regions of the cells and possibly also for monitoring the functioning (e.g., charging or current removal) of the cells of a battery to which the present application relates, the battery has a plate (cell connection and/or monitoring plate), which is arranged in the interior of the housing in the electrical connector region of the cells.
A plate is a carrier element for electronic components. It is also called a conductor board or a printed circuit board, and serves for both the mechanical attachment and electrical connection of electronic components. The connection lines are usually produced by etching a thin layer of conductive material on an insulating base board, and the components are soldered onto these conductor paths.
The plate is sensitive to breakage due to its design, and is subjected to load forces in the case of deformation of the housing (e.g., during a frontal crash of a vehicle) with a corresponding battery, which forces are caused by the deformation force on the housing. The plate can thereby be damaged or destroyed, which also results in dangers. For example, high short circuit currents can lead to overheating, or electric arcs to the ignition of mixtures. With high voltage batteries, there is also the danger that the housing will be charged.
According to the state of the art, the insulation plates that are used to protect the plates in batteries, only prevent a direct contact of the housing and the current-conducting parts in the interior of the housing. Thus, deformations of the cells including the cell terminal and the housing result, as well as tearing of cell connectors. As a voltage of about 120 Volts or more is present with high voltage batteries, the formation of electric arcs and/or an overload of the cells results.
The high load acting on the plate from the housing in the case of deformation of the known batteries is thus disadvantageous and can lead to damage, destruction and danger.
One object of the invention is to provide a battery with improved deformation safety, for example in the case of a crash.
This and other objects and advantages are achieved by the battery according to the invention (especially a lithium ion battery or nickel metal hydride battery), with a housing, a cell assembly of battery cells arranged in the housing and a plate arranged in the interior of the housing in the electrical connector region of the cells, for electrically connecting the cells. According to the invention, the battery also has support elements arranged in the interior of the housing. In the case of a deformation of the housing toward the plate by a deformation force exerted from the outside of the housing, the load forces exerted on the plate by the deformation of the housing are supported by the support elements, to protect the plate.
The support elements can be formed to conduct the load forces either around the plate or through it.
In an advantageous embodiment of the invention, the support elements formed on the cell assembly for the force distribution are provided by support elements that pass through the plate. The support elements can be formed for a large-area placement of the housing on the cell assembly or for the force distribution by means of support elements on the cell assembly passing through the plate.
According to a feature of the invention, the support elements for diverting the load forces are formed on the side of the cell assembly that faces the plate.
According to another embodiment of the invention, the load forces are transmitted by support elements inserted in the plate in a movable manner. However, the load forces can also be transmitted by support elements that are fixed in the plate, wherein the support elements are for example fixed through a passage in the plate or are glued into the plate.
The support elements may be formed as individual elements, (for example as pins), or as a surface element (for example, a board). The board is advantageously arranged on the side of the plate turned away from the electrical connector region of the cells. The board can further comprise supports passing through the plate.
In another embodiment of the invention, the plate for the force flow of the load forces comprises support elements worked into or integrated in the plate. The support elements can thereby for example be formed as support lugs or as stable electrical components which are arranged on the plate, such as coils. The support elements can further be arranged on the side of the plate turned towards the electrical connector region of the cells, or on both the side of the plate that is turned towards the electrical connector region of the cells and the side of the plate that is turned away from the electrical connector region of the cells.
The support elements may be formed for punctiform, linear or areal load distribution within the battery.
In a further embodiment of the invention, the support elements are formed for supporting an essentially horizontally progressing deformation force or load force, and for this purpose are aligned in an essentially horizontal orientation, related to the installation position of the battery.
The following advantages are achieved by the invention:
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
The entire cell block 5 can be surrounded with a covering sheet and can be filled with heat-conductive casting compound 8 prior to or after the insertion in the battery housing 2, which is not yet filled in
The gaps or spaces which are present between the cells 5 are filled with casting compound 8. The covering sheet also serves as a casting mold during filling of the casting compound 8. The cell assembly 6 formed during the casting with casting compound 8 is built into the battery housing 2 after the casting. The casting compound 8 is preferably a heat-conductive and/or electrically insulating material. Suitable materials for the casting compound 8 are for example an epoxy resin, or a rigid or curing foam, especially a polyurethane foam.
A plate 11 (cell connection plate) is arranged in the electrical connector region 10 of the cells 5. The side of the plate 11 that faces the housing 2 can be filled with a casting compound 8.
If an external deformation force 12 acts on the battery housing 2, it may be deformed in the manner indicated by the dotted line. Due to the deformation 13, battery components arranged in the interior of the battery housing 2 may be contacted, and receive a load force originating from the deformation 13. According to the invention, support elements 14 (which may be, for example passage pins or support lugs in the shown embodiment) are provided to divert these forces. In this manner, the load force is kept away from the plate 11, which is thus protected. A force path 15 results, which is drawn in as an example.
thus, in the embodiment of
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
Number | Date | Country | Kind |
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10 2007 010 738.4 | Feb 2007 | DE | national |
This application is a national stage of PCT International Application No. PCT/EP2008/001447, filed Feb. 23, 2008, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2007 010 738.4, filed Feb. 27, 2007, the entire disclosure of which is herein expressly incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2008/001447 | 2/23/2008 | WO | 00 | 3/9/2010 |