Patent Abstract:
A motor vehicle has an electric drive and at least one electrical energy storage module connected therewith. A guide extends longitudinally along the motor vehicle, and supports the storage module therein in a longitudinally displaceable manner relative to the motor vehicle.

Full Description:
CLAIM OF PRIORITY 
     Applicants hereby claim the priority benefits under the provisions of 35 U.S.C. §119, basing said claim of priority on German Patent Application Serial No. 10 2009 025430.7, filed Jun. 16, 2009. In accordance with the provisions of 35 U.S.C. §119 and Rule 55(b), a certified copy of the above-listed German patent application will be filed before grant of a patent. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a motor vehicle having an electric drive, and an electric energy storage module therefor. 
     Motor vehicles that are powered or driven, at least in part, with electrical energy (so-called hybrid drives) are among the prior art. The electrical energy for the electric drive is carried in storage modules that are also called battery packets. The weight of these storage modules is significant, particularly in motor vehicles that are driven exclusively by electricity. It is not uncommon for the storage modules to weigh 300 to 500 kg in order to attain a corresponding driving range. One problem associated with these large battery packets is their integration into existing vehicle concepts, i.e. adapting them to the so-called vehicle packaging. Another problem is the relatively long charging times required for the storage modules. Although the charging times are constantly being optimized and therefore further reduced, at low charge currents, it typically takes several hours to fully charge the storage modules. Alternatively, the empty storage modules can be exchanged for fully charged storage modules. Naturally, exchanging the storage modules must be quick and simple. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide a motor vehicle having an electric drive in which exchanging storage modules is simple and quick, and in which the storage modules can also be secured or attached with good crash resistance. 
     This object is attained in a motor vehicle having the features of patent claim  1 . 
     The subordinate claims relate to advantageous refinements of the inventive thought. 
     In the present inventive motor vehicle, the storage module or modules are supported and/or arranged in a guide that extends longitudinally along the motor vehicle. The storage modules are longitudinally displaceable relative to the guide. This construction simplifies the loading of the storage modules into the motor vehicle. Naturally, it also simplifies removing the storage modules from the motor vehicle. In addition, an impact damping unit may also be arranged at one or both ends of the guide. The present invention takes into consideration that the storage modules are relatively heavy, and consequently may move within the longitudinally extending guides in the motor vehicle during a crash. The storage modules should be retained in place by impact damping units arranged at each end of the guide in order to prevent the storage modules from being damaged themselves, or even shifting longitudinally out of the guide during an abrupt deceleration. The crash or impact energy imparted to the storage modules is dissipated and converted to a different energy. In particular, the crash energy is absorbed by the impact damping unit through deformation. 
     Moreover, the arrangement of the guide in the longitudinal direction of the motor vehicle has the advantage that the weight of the storage module is distributed onto both the front axle and the rear axle of the motor vehicle. The guide preferably extends from the front axle to the rear axle of the motor vehicle. The guide can be configured in the form of a channel that connects the front and rear axles of the vehicle to one another. Positioning the storage module, and/or the guide, in the laterally center portion of the motor vehicle is also advantageous. 
     An impact damping unit is preferably provided, at least in the front area of the motor vehicle. In one advantageous refinement of the invention, the impact damping unit extends to a front bumper portion of the motor vehicle. This makes it possible to distribute the weight of the storage module across nearly the entire length of the motor vehicle. It is also possible to position the impact damping unit directly in the guide. In this case, no additional space outside of the guide is needed for the impact damping unit. The impact damping unit can be supported on a retention plate attached at one end of the guide. 
     The storage module typically comprises a plurality of individual storage elements. Disposed therein are individual battery or accumulator cells with associated electronic units. For safety reasons, the voltage is limited e.g. to 60 volts direct current for each storage element. 
     In a practical embodiment of the present invention, the guide preferably has an upwardly opening, C-shaped cross-sectional configuration. Thus, the guide has a base on the bottom, upward-facing legs connected longitudinally to each side of the base, and bars connected to the legs that face one another and define open guide grooves. Such a guide, which can also be called a rail, secures the storage elements or a storage module held therein very securely against laterally acting forces. The C-shaped configuration also protects the individual storage elements against vertical displacement. The individual storage elements are, at least in part, laterally enclosed, and therefore positively connected with the guide. The only freedom of movement of the storage module is longitudinal displacement along the guide. The storage module preferably includes seating units that are arranged in a longitudinally displaceable fashion in the guide. The storage elements fit into the seating units. In other words, the storage elements are not held directly by the guide, but rather are mechanically connected to seating units which are in turn supported in the C-shaped guide. 
     The seating units orient the storage elements in the same manner and orientation as the guide groove retains the seating units. More specifically, the seating units grip lateral retention bars on the storage elements. What is important is that all of the storage elements can be displaced only in the longitudinal direction of the guide. The seating units and the storage elements thus have a positive interconnection using fitting elements that are configured to fit with one another, such as using a groove and spring arrangement. 
     The seating unit may theoretically be longer than the storage elements when the same are arranged in a row. The number of storage elements may be coordinated with the associated vehicle type. 
     The present invention makes it possible to attach or mount a standardized storage module in a vehicle very rigidly. The storage elements are combined to create an elongate storage module that can be placed in a centrally disposed channel in the motor vehicle in a manner that conserves a good deal of space. The channel may extend between and interconnect the front axle to the rear axle of the vehicle. This connection has a positive effect on strength, and thus the behavior of the chassis. Because of the freedom in the selection of the material for the guide, it is possible to produce the guide from lightweight metals, especially aluminum, plastic, or composite materials, regardless of the materials used in other components of the motor vehicle. This design minimizes weight, while retaining substantial strength. Naturally, the freedom in the selection of the material can also reduce costs. The assembly and exchange of the storage module and storage elements is simple and inexpensive, while simultaneously providing excellent results in side crashes. The “resilient” or non-static support of the storage module is achieved by integrating in the support a crush box or impact damping unit. In a crash, the crush box makes it possible to absorb the associated kinematic energy, so as to avoid the need for the other party involved in the crash to absorb this impact energy. 
     These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention shall be explained in greater detail in the following using the exemplary embodiment depicted schematically in the drawings. 
         FIG. 1  depicts the chassis of a motor vehicle having a guide that extends in the longitudinal direction of the motor vehicle; 
         FIG. 2  is a perspective elevation of the guide in  FIG. 1 ; 
         FIG. 3  depicts a section through the guide depicted in  FIG. 2 ; and, 
         FIG. 4  depicts an alternative to the motor vehicle in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
       FIG. 1  is a highly simplified schematic depiction of the chassis portion of a motor vehicle  1 . It can be seen that a guide  4  is disposed in the center of the motor vehicle  1 , and extends longitudinally along the motor vehicle  1  between a front axle  2  and a rear axle  3 . The guide  4  is depicted in detail in  FIGS. 2 and 3 . The illustrated guide  4  connects the schematically depicted front axle  2  with the rear axle  3 . An impact damping unit  6 , also known as a crush box, is disposed on the front end  5  of the guide  4 . This impact damping unit  6  extends to a front bumper  7  that is also connected via crush boxes  8  to the body of the motor vehicle  1 . 
     The guide  4  receives and supports individual storage elements  9 . In this exemplary embodiment, the storage elements  9  are configured as rectangular units, and are placed into the guide  4  from the rear of the motor vehicle  1 . All together, the storage elements  9  and lateral seating units  15 ,  16  form a storage module  19  ( FIGS. 2 and 3 ). The guide  4  is a component of a channel  10 , wherein the guide  4  defines the lower portion of the channel  10 , as can be seen in  FIG. 2 . The guide  4  is configured open on top and with a C-shaped cross-section. The guide  4  includes a base  11  that defines or forms the bottom of the channel  10 . Legs  12 , that extend upwardly in the plane of  FIG. 3 , are attached longitudinally to each side of the base  11 . Bars  13  are located on the upper portions of the legs  12  and face one another, so as to form or define mutually opposing undercut guide grooves  14  along the longitudinal portions of the base  11 . A longitudinally displaceable seating unit  15 ,  16  for the storage module  19  is disposed in each of the guide grooves  14 . These seating units  15 ,  16  are retained in and held by the guide grooves  14 , and have a generally U-shaped cross-sectional shape. Seating units  15 ,  16  grip longitudinally protruding retention bars  17 ,  18  on the storage elements  9 . Retaining elements  20 , in the form of bolts or the like, mechanically join the individual storage elements  9  to the seating units  15 ,  16 . In this exemplary embodiment, one retaining element  20  is provided on each side of each storage element  9 , with the retaining elements  20  being arranged opposite one another. 
     The guide  4 , and/or the seating units  15 ,  16 , may have an extruded construction. The longitudinal extension of the seating units  15 ,  16  in the guide  4  is longer than a single storage element  9 . The seating units  15 ,  16  act to some extent as an adapter between the storage elements  9  and the guide  4 . Consequently, it is possible to use the same guide  4  for storage elements  9  that have differently shaped retention bars or other connectors, simply by using alternatively configured seating units  15 ,  16  in the inventive motor vehicle. 
       FIG. 4  depicts a modification to the embodiment in  FIG. 1 . The impact damping unit  6  is arranged immediately at the end  5  of the guide  4 , and more specifically, within the guide  4 . Thus, it is shorter than the construction shown in  FIG. 1 , and does not extend to the bumper  7 . A support plate  21  at the end of the guide  4  acts as a counterbearing that supports the impact damping unit  6 . 
     In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise. 
     Legend: 
       1 —Motor vehicle 
       2 —Front axle 
       3 —Rear axle 
       4 —Guide 
       5 —End 
       6 —Impact damping unit 
       7 —Bumper 
       8 —Crush box 
       9 —Storage element 
       10 —Channel 
       11 —Base 
       12 —Leg 
       13 —Bar 
       14 —Guide groove 
       15 —Seating unit 
       16 —Seating unit 
       17 —Retention bar 
       18 —Retention bar 
       19 —Storage module 
       20 —Retention element 
       21 —Support plate

Technology Classification (CPC): 1