Abstract:
The invention relates to a bicycle frame comprising a tube section having an interior space for receiving at least one battery unit that is suitable as a source of energy for an electromotive bicycle drive, as well as to a battery unit insertable therein. 
     To provide an easy operation and at the same time a highly stabilized placement of the battery, it is suggested that said tube section is provided with a lateral opening substantially extending in the direction of extension of said tube section, wherein said battery unit is insertable into said interior space through said lateral opening.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a bicycle frame comprising a tube section having an interior space for receiving at least one battery unit that is suitable as a source of energy for an electromotive bicycle drive. The invention further relates to a battery unit for insertion into such a bicycle frame. 
     BACKGROUND OF THE INVENTION 
     Electric motors are used in bicycles both as a full drive and as an auxiliary or hybrid drive, the electric motor, when required, acting either as a complete bicycle drive or to assist the pedal drive actuated by the cyclist. As sources of energy for such a motor, batteries, more particularly rechargeable batteries are required, which are conventionally fastened to the bicycle frame in a suitable location. To this end, the bicycle frame is usually provided with a battery container. However, such a battery container is relatively bulky and not only reduces the free space otherwise available on the bicycle frame, particularly for accommodating additional equipment such as water bottles, bicycle tools, etc., but may even impair the cycling comfort for the cyclist in the extreme case. In addition, securing the battery inside such a container also represents a problem since it has a significant own weight but occasionally has to withstand hard shocks during cycling. 
     EP 0 905 014 B1 discloses a motor-driven folding bicycle in the rear frame section of which a battery for its electric drive is stored. When the front frame section is folded around the rear frame section, a frontal opening on the front side of the rear frame section is uncovered through which the battery compartment is accessible from the outside. However, such a frontal opening is only convenient in folding bicycles since the front side of a non-folding bicycle is normally covered by the bicycle lights, the brake lines, etc., and is only insufficiently accessible. Furthermore, the possibility of securing the battery in the frame interior is also limited by this frontal opening. For a reliable battery retention that is also protected against hard shocks of the frame a force application to the battery in the longitudinal direction of the frame would be necessary. However, since the frontal frame opening requires a manual insertion of the battery against the action of such a force, only relatively small retaining forces may be employable in such a battery holder. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a bicycle frame of the kind mentioned in the introduction that allows a simple insertion and removal of a battery unit into and from the interior of the frame tube while avoiding the foregoing disadvantages, and that simultaneously ensures a reliable and safely protected accommodation of the battery. 
     This is accomplished by a bicycle frame wherein the tube section of the bicycle frame has a lateral opening substantially extending in the direction of the extension of said tube section, wherein said battery unit is insertable into said interior space through said lateral opening. In this manner, a simple insertion and removal of the battery into and from the interior is possible transversally to the frame. At the same time, such an inserting mechanism allows the arrangement of a highly stable battery fixture over the corresponding tube length of the interior. The dependent claims indicate preferred embodiments of this bicycle frame and of a battery unit insertable therein. 
     A particularly comfortable insertion and removal of the battery unit can be achieved through a swinging arrangement that provides a guidance of the manual operation and allows a precise positioning of the battery. Preferably, a hinge is arranged at one end of the interior space to which the battery unit can be coupled and swung around toward the interior space after the coupling operation. Nearby this hinge, an electric contact for the battery unit is preferably arranged such that the contact with the electromotive drive is already established when it is coupled to the hinge. In a further preferred manner, a closure lid for the lateral opening is hinged to the hinge. This offers the advantage that on one hand, the closure lid may serve to determine an inserting direction of the battery for coupling it to said hinge, and on the other hand, that a simultaneous closure of the lateral opening can be achieved during the insertion of the battery unit in the course of the swinging movement performed. 
     To achieve a safe battery fixture, according to a preferred embodiment, it is suggested that a tensioning device is arranged in the interior space, the tensioning device allowing an application of a tension force to the battery unit in the direction of extension of the tube section. In a further preferred embodiment in which according to the foregoing explanations a hinge is arranged at one end of the interior space, the tensioning device is arranged at the end of the interior space opposite the hinge. The tension force produced by the tensioning device is preferably equal to at least 100 N, preferably about 150 N, and may e.g. be created by the arrangement of at least one spring that is preferably pretensioned during the operation of inserting the battery unit already, and/or by a rotatably mounted axle by which the tension force may e.g. be applied to the battery unit after its insertion. 
     According to a first preferred embodiment of the tensioning device, the latter comprises at least one pivot arm capable of pivoting between an outer position in which the pivot arm is directed toward the lateral opening, and an inner position in which the pivot arm is brought nearer to the direction of extension of the tube section, the pivot arm being fixable to the battery unit during the insertion of the latter. In this case, a spring for producing the tension force may be coupled to the pivot arm and may e.g. be partly integrated in its interior. 
     According to a second embodiment, the tensioning device comprises a guide roller along which the battery unit is guided during its insertion into the interior space. In this case, the guide roller may be coupled to a spring for creating the tension force. 
     According to a third embodiment, the tensioning device comprises a rotatably mounted axle by which, as already explained above, the tension force can be applied to the battery unit after its insertion. 
     A battery unit for insertion into such a bicycle frame is preferably provided on its rear side with a connecting section designed for coupling the same to the aforementioned hinge. On its front side, a battery unit according to the invention is preferably provided with a projecting or recessed structure for coupling it to the aforementioned tensioning device. In this manner, e.g. a coupling to the aforementioned pivot arm or a snap engagement on the aforementioned guide roller may be achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail hereinafter by means of preferred embodiments and with reference to the drawings from which further features and advantages of the invention will become apparent. The figures show: 
         FIG. 1 : a lateral view of a conventional battery-operated bicycle; 
         FIG. 2 : a lateral view of a bicycle frame of the invention comprising a tube section for receiving a battery unit; 
         FIG. 3 : an enlarged perspective view of the tube section shown in  FIG. 2  for receiving a battery unit with the closed closure lid; 
         FIG. 4 : a perspective view of the tube section shown in  FIG. 3  with the open closure lid; 
         FIGS. 5(   a )-( h ): respective sectional views of the tube section according to  FIGS. 3 and 4  in which a tensioning device according to a first embodiment of the invention is integrated, the views illustrating respective steps for inserting a battery unit into the interior space of the tube; 
         FIGS. 6(   a )-( c ): respective sectional views of a tube section in which a tensioning device according to a second embodiment of the invention is integrated, the views illustrating respective steps for inserting a battery unit into the interior space of the tube; 
         FIGS. 7(   a )-( d ): respective sectional views of a tube section in which a tensioning device according to a third embodiment of the invention is integrated,  FIG. 7(   b ) illustrating a section according to the sectional plane indicated in  FIG. 7(   a ), and  FIGS. 7(   a ),  7 ( c ), and  7 ( d ) illustrating respective steps for inserting a battery unit into the interior space of the tube section according to the same sectional view; 
         FIGS. 8(   a ),( b ): respective sectional views of a tube section in which a tensioning device according to a fourth embodiment of the invention is integrated,  FIG. 8(   a ) showing the tensioning device in the tensioned state and  FIG. 8(   b ) showing the tensioning device in the untensioned state; and 
         FIGS. 9(   a ),( b ): a top view of a portion of a closure lid of the invention and a guide plate for the guidance thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , an electromotively driven bicycle  1  of the prior art is shown with a bicycle frame  2  on the down tube of which a battery enclosure  3  for receiving a battery unit is mounted, the latter supplying the energy for an electric motor  4  arranged on the rear wheel. Such a known electric motor  4  may be used both as a full bicycle drive and as a hybrid drive where the cyclist&#39;s muscular force is assisted depending on the drive force transmitted to the rear wheel by the pedal drive. 
       FIG. 2  shows a bicycle frame  5  of the invention. The frame is essentially composed of a seat tube  6 , a top tube  7  and a down tube  8  arranged in a triangular shape, as well as of a head tube  9  on the front side and two seat stays  10  and two chain stays  11  arranged on the frame on the rear side thereof. As compared to seat tube  6  and top tube  7 , down tube  8  has a cross-sectional shape that is extended in the plane of the frame, thereby creating an enlarged tube cross-section. In tube mid-section  12  of down tube  8 , a closure lid  13  for a lateral opening  14  is arranged that is shown in more detail in  FIG. 4 . 
       FIG. 3  shows a detail of bicycle frame  5  in an enlarged view again illustrating down tube  8  with the closed closure lid  13 . 
       FIG. 4  shows the same detail with the open closure lid  13  whereby interior space  15  of tube mid-section  12  is accessible from the outside through lateral opening  14 . Lateral opening  14  extends in the longitudinal direction of tube section  12  and over a substantial portion of the interior space  15 . 
     Furthermore, in  FIG. 4 , a battery unit  16  for insertion into interior space  15  is shown. Battery unit  16  is essentially cylindrical in shape with an octagonal cross-section. The shape of the area of interior space  15  located behind lateral opening  14  is adapted to the external contour of battery unit  16 . At its rear end, closure lid  13  is rigidly connected to a connecting socket  17  that projects into interior space  15  and into which battery unit  16  is pluggable by its rear side. Along closure lid  13 , battery unit  16  can be manually guided toward its correct connecting position in connecting socket  17 . 
     Connecting socket  17  is hinged at the rear end of interior space  15 , as explained in more detail hereinafter, thereby allowing to swing around closure lid  13  with plugged in battery unit  16  transversally to lateral opening  14 . On the front end of battery unit  16 , several projecting structures  18  are formed by which battery unit  16  is adapted to engage in a tensioning device  20 , as will be explained in more detail with reference to the following figures also. 
       FIG. 5(   a ) shows down tube  8  in a sectional view. The Figure shows a hinge  21  arranged at the rear end of interior space  15 , to which connecting socket  17  is hinged along with closure lid  13  fastened thereto. Furthermore, connecting socket  17  is provided with an electric contact  22  for battery unit  16  that is pluggable therein. 
     At the frontal end of interior space  15 , tensioning device  20  for tensioning battery unit  16  in the direction of the bicycle frame  5  is arranged. Tensioning device  20  comprises a pivot arm  23  in the interior of which a spring  24  for producing the tension force is arranged. In an inner position, pivot arm  23  is located near the down tube axis and is hinged to a tensioning axle  25  so as to be able to pivot between its inner position and an outer position in which it is directed toward lateral opening  14 , this pivoting movement taking place in the same pivoting plane as that of connecting socket  17 . At the outer end of pivot arm  23 , a rounded taper  26  is formed that serves for its engagement in the correspondingly shaped raised structure  18  on battery unit  16  in order to achieve a coupling of battery unit  16  to tensioning device  20  during the inserting operation. 
     A coil spring  27  is wound around tensioning axle  25 . On the outer wall of tube section  12  opposite lateral opening  14 , a push button  28  with an attached return spring is arranged that is operatively connected to pivot arm  23 . 
     Hereinafter, the consecutive steps for inserting battery unit  16  into interior space  15  are explained in more detail with reference to  FIGS. 5(   b )- 5 ( h ). 
       FIG. 5(   b ) shows down tube  8  after the actuation of push button  28 . Coil spring  27  is thus released, thereby producing a rotation of tensioning axle  25  and a resulting pivoting movement of pivot arm  23  from its inner position to its outer position. At the same time, the locking mechanism of closure lid  13  is unlocked so that the latter may be opened manually. 
       FIG. 5(   c ) shows down tube  8  after opening closure lid  13  around hinge  21 . 
       FIG. 5(   d ) shows battery unit  16  that is being guided toward connecting socket  17  along the inner side of opened closure lid  13 . Here, especially the rearward connecting section  29  of battery unit  16  that is to be introduced into connecting socket  17  is visible, which forms an electric contact. 
       FIG. 5(   e ) shows battery unit  16  after the introduction of connecting section  29  into connecting socket  17 , whereby the battery is already electrically connected on this side. 
       FIG. 5(   f ) shows battery unit  16  after swinging back closure lid  13 , whereby battery unit  16  is guided toward lateral opening  14  along its longitudinal side until its frontal raised structure  18  abuts to pivot arm  23  and enters into engagement with taper  26  at the end thereof. 
       FIG. 5(   g ) shows battery unit  16  after further swinging back closure lid  13  while pivot arm  23  engaged on the battery unit is carried along. In this manner, an increasing tension of spring  24  and an accompanying force application to battery unit  16  are created. 
       FIG. 5(   h ) shows battery unit  16  after its complete insertion into interior space  15  with closure lid  13  locked. Pivot arm  23  is now completely brought back to its inner position, whereby a maximum spring tension and force application to battery unit  16  is achieved. By such a tensioning device  20 , a high tension force can be transmitted to battery unit  16 , whereby a high horizontal stability is achieved. 
     To remove battery unit  16  from interior space  15 , push button  28  has to be actuated, thereby causing closure lid  13  to be unlocked so that closure lid  13  can be swung out. In spite of the relatively high tension force, the manual releasing force required therefore is very small. 
       FIG. 6(   a ) shows a tube section  12  with a tensioning device  30  according to a second embodiment of the invention. Tensioning device  30  comprises a guide roller  33  that is coupled by a pivot arm  31  to a coil spring  34  arranged nearer to the rear wall side. On its other side, coil spring  34  is rigidly connected to tube section  12 . Pivot arm  31  is hinged to an axle  19  arranged in coil spring  34  such that a movement component of guide roller  33  in the direction of extension of tube section  12  is ensured. Further illustrated is battery unit  16  that is already plugged into connecting socket  17 . On the front side of battery unit  16 , a circular recess  32  is formed whose shape corresponds to a segment of the circumference of guide roller  33 , thereby allowing a snap engagement. 
       FIG. 6(   b ) shows battery unit  16  after swinging closure lid  13  around until the front side of battery unit  16  enters into contact with guide roller  33 . As battery unit  16  is further introduced, guide roller  33  is set into rotation and coil spring  34  is tensioned, thereby achieving an increasing force application to guide roller  33  in the direction of battery unit  16 . 
       FIG. 6(   c ) shows battery unit  16  after its complete insertion into interior space  15  of tube section  12 . Guide roller  33  is engaged in recess  32  and closure lid  13  is closed. 
       FIG. 7(   a ) shows a tube section  12  with a tensioning device  35  according to a third embodiment of the invention. Tensioning device  35  comprises a guide roller  33 . Furthermore, battery unit  17  plugged into connecting socket  16  is illustrated again. 
       FIG. 7(   b ) shows tube section  12  illustrated in  FIG. 7(   a ) in a sectional view according to the sectional plane indicated in  FIG. 7(   a ). In this Figure it is seen that tensioning device  35  is associated to a spring pair  36  arranged at the end of interior space  15 . 
       FIG. 7(   c ) shows tube section  12  according to the view of  FIG. 7(   a ) with the front side of battery unit  16  brought into contact with guide roller  33 . Here also, a further swinging movement of closure lid  13  results in an increasing force application to battery unit  16  until its circular recess engages in guide roller  33 , as shown in  FIG. 7(   d ). 
       FIG. 8(   a ) shows a tube section  12  with a tensioning device  40  according to a fourth embodiment of the invention. Tensioning device  40  comprises a rotatably mounted axle  41  that is manually actuatable from the outside. Axle  41  has a twisting bolt  42  hinged thereto, and to the opposite side of the latter, a locking pin  43  is hinged. Further illustrated is battery unit  16  that is already inserted in interior space  15 . Tensioning device  40  is in the untensioned state. 
       FIG. 8(   b ) shows tube section  12  after a rotation of axle  41  whereby the twisting bolt is moved toward the battery unit and the locking pin abuts to the front side of battery unit  16  such that an increasing tension force is applied to battery unit  16  as axle  41  is further rotated. 
       FIGS. 9(   a ) and  9 ( b ) show closure lid  13  in a top view with a guide pin  45  fastened thereto. The guide pin engages in rail  47  of a guide plate  46  that is fastened to a tube section  12 . In the outer end area of rail  47 , a detent structure  48  is formed by which closure lid  13  is locked in its outer end position. 
     From the preceding description, modifications of the bicycle frame of the invention are apparent to one skilled in the art without departing from the scope of protection of the invention that is solely defined by the patent claims. Thus, inter alia:
         instead of down tube  8 , tube section  12  with interior space  15  for receiving at least one battery unit  16  may e.g. also be formed by top tube  7  or seat tube  6  of the bicycle frame geometry and may either extend over the entire tube length or only over a portion of the respective frame tube.   Besides the shown exemplary embodiments using one respective tensioning device  20 ,  30 ,  35 ,  40 , it is also possible to use a combination of such tensioning devices, e.g. through the combination of a spring tension and of a force application by means of a rotatably mounted axle in order to achieve a desired tensioning action.       

     Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.