Safety device for a sealed cell

Abstract

A safety device for a sealed cell ( 1 ) comprising alternating positive and negative electrodes respectively connected to positive and negative current output terminals ( 6, 7 ) placed in a container ( 2 ) having an end ( 3 ) that is closed by a wall. The wall of the closed end presents thinning ( 13 ) adapted to be torn by excess pressure inside the container, and the thinning is adapted, on being torn, to interrupt electrical conduction between the electrodes of one polarity and the corresponding current output terminal. The device of the invention is simple in design, is capable of operating at low pressures, and over a wide range of pressures, and acts as a circuit interrupter without decreasing the current density that flows in the electrical circuit.

1 . A safety device for a sealed cell comprising alternating positive and negative electrodes respectively connected to positive and negative current output terminals, the electrodes being disposed in a container presenting an end that is closed by a wall presenting thinning adapted to be torn by excess pressure inside the container, the thinning being adapted, on being torn, to interrupt electrical conduction between the electrodes of one polarity and the corresponding current output terminal.  
     
     
         2 . A safety device according to  claim 1 , in which the thinning constitutes a zone of weakness in the wall at the closed end.  
     
     
         3 . A safety device according to  claim 1 , in which the end closed by a wall supports the current output terminals.  
     
     
         4 . A safety device according to  claim 1 , in which a cover placed on an open end of the container supports the current output terminals.  
     
     
         5 . A safety device according to  claim 1 , in which the tear is adapted to interrupt electrical conduction between the positive electrodes and the positive current output terminal.  
     
     
         6 . A safety device according  claim 1 , in which the tear is adapted to interrupt electrical conduction between the negative electrodes and the negative current output terminal.  
     
     
         7 . A safety device according to  claim 1 , for a cylindrical format sealed cell.  
     
     
         8 . A safety device according to  claim 1 , for a prismatic format sealed cell.  
     
     
         9 . A safety device according to  claim 1 , for a cell operating with pressures inside the container lying in the range 4 bars to 20 bars.  
     
     
         10 . A safety device according to  claim 9 , wherein the pressures inside the container lie in the range 8 bars to 12 bars.  
     
     
         11 . A safety device according to  claim 1 , in which the thickness of the thinning represents substantially 20% of the thickness of the wall at the closed end of the container.  
     
     
         12 . A safety device according to  claim 1 , including a rim of the closed end wall, said rim being adapted to prevent the electrodes being ejected in the event of the thinning being torn.  
     
     
         13 . A method of manufacturing a safety device for a sealed cell, the method comprising the steps consisting in: 
 providing a container presenting an end that is closed by a wall;    stamping the wall at the closed end so as to create thinning suitable for being torn by excess pressure inside the container;    placing a stack of positive and negative electrodes inside the container;    connecting the electrodes to current output terminals so that tearing the thinning interrupts electrical conduction between the terminals of one polarity and the corresponding current output terminal; and    closing the cell in sealed manner.