Patent Publication Number: US-2010123432-A1

Title: Battery charger

Description:
This claims the benefits of German Patent Application No. 10 2008 043 852.9, filed Nov. 19, 2009 and hereby incorporated by reference herein. 
     The present invention relates to a battery charger. Such battery chargers usually have a mains connection to supply power and at least one cradle for a battery or battery pack. 
     BACKGROUND 
     U.S. patent publication US2007/0236177A discloses a generic battery charger including a housing, an electronic charging unit arranged in the housing, a cradle to hold a battery that is to be charged and counter-contact elements arranged in the area of the cradle for the contact elements of the battery. 
     SUMMARY OF THE INVENTION 
     A battery can be electrically recharged by means of this battery charger. In a parallel patent application of the applicant, a battery pack is claimed that not only entails the possibility to store electric current but that also has a gas reservoir to store a gaseous medium that is under pressure such as, for example, compressed air. With a conventional battery charger, only the battery cells of this battery pack can be charged, while the gas reservoir has to be charged using a separate charger. 
     It is an object of the present invention to develop a battery charger of the above-mentioned type that allows the battery cells to be charged with electric energy and, in parallel, the gas reservoir to be charged with a gaseous medium. 
     The present invention provides a battery charger having a housing, an electronic charging unit and a cradle for a battery pack that has electric counter-contact elements for contact elements of the battery pack. The battery charger has a filling device to fill gas reservoirs such as, for instance, pressure vessels, with gaseous media. As a result, a battery pack that is attached to the battery charger can be charged with electric energy while simultaneously, its gas reservoir can be filled with a gaseous medium or compressed air. 
     Advantageously, the filling device includes a compressor that generates compressed air and that is pneumatically connected to at least one connection means for an output port of a gas reservoir. In a simple manner, the (electrically operated) compressor can generate compressed air, with which a gas reservoir configured as a pressure vessel can be refilled in the battery pack. Moreover, the compressor could also provide compressed air for other applications via the battery charger. For this purpose, the charger could be operated via a selector switch in various modes, at least one of which allows it to be operated exclusively as a compressor. 
     It is likewise advantageous for the counter-contact elements and the at least one connection means to be arranged on a shared counter-connection port so that, when the battery pack is coupled to the battery charger, the contact elements and the output port of the battery pack are simultaneously connected to the counter-contacts and to the connection means located on the charger. 
     It is likewise practical for the filling device to be controlled via the electronic charging unit. In this context, the electronic charging unit can recognize, preferably automatically, whether a (or the correct) battery pack is attached to the charger and can then automatically switch on the filling device. Moreover, the electronic charging unit can communicate with the electronic unit of the battery and, in this manner, can monitor the charging procedure of the gas reservoir by means of appropriate sensors (e.g. pressure sensor, temperature sensor) located on the gas reservoir. In this context, it is advantageous for the compressor of the filling device to be electrically connected to the electronic charging unit, so that the compressor can be controlled by the electronic charging unit as a function of the sensor data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The drawing is a view of one embodiment of the battery charger of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is presented in the drawing with reference to an embodiment, whereby the drawing shows a battery charger  30  with a battery pack  10  attached to it. 
     The battery pack  10  has a housing  11  and a plurality of battery cells  12  that are electrically connected to each other and arranged in the housing  11 . In this context, the battery pack can be configured, for instance, as a lithium-titanate, NiCd, NiMH, Li-ion, Li-polymer or Li—Fe battery. 
     The battery pack  10  also has an electronic unit  13  configured as an electronic control unit that is electrically connected to the battery cells  12  and monitors them, said electric unit being connected via an electric line  14  to electric contact elements  18  that are arranged on the housing  11 . The contact elements  18  are arranged at a connection port  17  that can be connected to a counter-connection port  37  of a battery charger  30 , to a hand-held power tool or the like. The electronic unit  13  is also connected to a temperature sensor  21  such as, for instance, an NTC (negative temperature coefficient thermistor), as a result of which the temperature of the battery cells  12  can be monitored. 
     The housing  11  of the battery pack  10  also contains a gas reservoir  15  configured as a pressure vessel for a gaseous medium that is under pressure such as, for example, compressed air. Here, the gas reservoir  15  is connected via a pressure line  16  to an output port  19  that is arranged adjacent to the contact elements  18  at the connection port  17  on the outside of the housing  11 . Moreover, a valve  20  that, without being activated, prevents gas or gaseous medium from flowing out of the gas reservoir  15  is arranged in the line  16  near the output port  19 . 
     The battery charger  30  has a housing  40 , an electronic charging unit  33  arranged in this housing  40  as well as a mains connection  32  to supply electric power. Moreover, the battery charger  30  also has a filling device to fill gas reservoirs  15  with gaseous media. The filling device has a compressor  35  to generate compressed air (as the gaseous medium) that is connected via a line  36  to a connection means  39  and that can draw in air, preferably filtered, via an air intake  34 . The connection means  39  is arranged together with electric counter-contact elements  38  at a counter-connection port  37  for the connection port  17  of the battery pack  10  in the area of a cradle  31  of the battery charger  30  for the battery pack  10 . When the battery pack  10  is placed into the cradle  31  of the battery charger  30 , the connection port  17  is coupled to the counter-connection port  37  and, at the same time, an electric connection is established between the contact elements  18  and the counter-contact elements  38 , and a pneumatic connection is established between the output port  19  and the connection means  39 . The electronic charging unit  33 , which is, on the one hand, electrically connected to the counter-contact elements  38  and, on the other hand, electrically connected to compressor  35 , charges the battery cells  12  with electricity and, in parallel to that, once again fills the gas reservoir  15  of the battery pack  10 , with gaseous medium in the form of compressed air. The filling procedure of the gas reservoir  15  can be completed considerably faster than the charging procedure of the battery cells  12  of the battery pack  10 . 
     During the operation of the compressor  35 , the valve  20  at the output port  19  of the battery pack  10  is automatically opened by the excess pressure generated by the compressor in order to allow the gas reservoir to be filled with compressed air. In this process, the valve  20  remains open until the pressure in the gas reservoir  15  has reached a certain value that corresponds to the excess pressure generated by the compressor.