Battery pack for cordless device

Abstract

A battery pack 13 (FIG. 2 ) comprises an elongated cylindrical, metal casing 35 , a plurality of cells 41, 43 in casing 35 and three coaxial pack terminals 46, 54, 61 . For enhanced convenience, pack terminals 46, 54, 61 are electrically connectable in a cordless device 11 regardless of the angular orientation of the pack 13 about casing axis 33 . To reduce cost and increase durability, pack 13 has no welded connections and will permit high current discharge rates. Cells 41, 43 are electrically connected but are mechanically disconnected. A spring 73 engages cell 41 and biases cells 41, 43 tightly together in compression to form good, low resistance electrical contact between cells 41, 43 , casing base cap 45 and top 53 . To provide a pack with two output voltages, the third pack terminal 61 has a polarity (relative to first pack terminal 46 ) the same as second pack terminal 54 and is electrically connected to the cell can terminal 43 b of forward cell 43 , thereby electrically by-passing cell 43.

We claim:  
     
       1. A battery pack comprising: 
       a casing having a longitudinal axis and having opposed rear and forward ends;  
       a plurality of cells in the casing, each cell having first and second cell terminals, said casing adapted to securingly retain said cells within said casing; and  
       first and second pack terminals having opposite polarities, coaxial with the casing axis, located adjacent to the casing forward end and electrically connectable in a cordless device regardless of the angular orientation of the pack about the casing axis.  
     
     
       2. The pack recited in claim  1 , wherein, the forward end of said casing is open and a cavity is defined within the casing at the open forward end, and said second pack terminal is disposed within the cavity and terminates rearwardly of said open forward end. 
     
     
       3. The pack recited in claim  1 , said casing being cylindrical, each said first cell terminal comprising a cell can and each said second terminal comprising a cell button, wherein, the button terminal of the forwardmost cell is exposed at the casing forward end and constitutes the second pack terminal. 
     
     
       4. The pack recited in claim  3 , wherein, the forward end of said casing is open and a cavity is defined within the casing at the open forward end, and said button terminal of the forwardmost cell terminates rearwardly of said open forward end of said casing within the cavity. 
     
     
       5. The pack recited in claim  1 , said pack further comprising an electrically conducting strap welded at one end to the first pack terminal and at the other end to the first cell terminal of a rearwardmost cell. 
     
     
       6. The pack recited in claim  1  further comprising a third pack terminal. 
     
     
       7. The pack recited in claim  1 , said casing being cylindrical, said first and second pack terminals disposed symmetrically about said longitudinal axis. 
     
     
       8. A cordless device comprising: 
       a cavity;  
       a receptacle in the cavity;  
       a battery pack removably located in the cavity and comprising a casing and a plurality of cells in the casing, said casing having a longitudinal axis and having opposed rear and forward ends, each cell having first and second cell terminals; and 
       a battery pack removably located in the cavity and comprising a casing and a plurality of cells;  
       
         said casing having a longitudinal axis, opposed rear and forward ends, and adapted to securingly retain said cells therein;  
       
       
         each of said plurality of cells having first and second cell terminals; and 
       
       terminal meansterminals for electrically connecting the pack and receptacle together regardless of the angular orientation, relative to the receptacle, of the pack about the casing axis.  
     
     
       9. The device recited in claim  8 , said casing being cylindrical and said terminal means including first and second pack terminals disposed coaxially about the casing axis. 
     
     
       10. The device recited in claim  9 , said terminal means including a third pack terminal disposed coaxially about the casing axis. 
     
     
       11. The device recited in claim  9 , wherein, said receptacle has a housing defining a receptacle cavity having a longitudinal axis coaxial to the casing axis and receiving the casing forward end; and 
       the terminal means comprises further comprising first and second receptacle terminals coaxial to the receptacle axis and mating respectively with the first and second pack terminals.  
     
     
       12. A cordless device comprising; 
       a cavity;  
       a receptacle disposed in the cavity, said receptacle having a housing defining a receptacle cavity, the receptacle cavity having a longitudinal axis;  
       a first receptacle terminal disposed within the receptacle cavity;  
       a second receptacle terminal disposed within the receptacle cavity; and  
       a battery pack removably located in the cavity, said battery pack including an elongated cylindrical casing having a longitudinal axis of symmetry coaxial to the longitudinal axis of the receptacle cavity and opposed rear and forward ends, a plurality of cells disposed  securingly retained in the casing, and first and second pack terminals, each said cell having first and second cell terminals; wherein,  
       said first receptacle terminal mates with the first pack terminal and said second receptacle terminal mates with the second pack terminal, the pack terminals are coaxial with the casing axis, and the pack terminals are located adjacent to the casing forward end and are electrically connectable to the receptacle terminals regardless of the angular orientation of the battery pack about the casing axis.  
     
     
       13. The device recited in claim  9 , said terminal means including a third pack terminal disposed coaxially about the casing axis. 
     
     
       14. A cordless device comprising: 
       a longitudinally extending cavity;  
       a receptacle disposed in the cavity, said receptacle having a housing defining a receptacle cavity, the receptacle cavity having a longitudinal axis;  
       a first receptacle terminal disposed within the receptacle cavity;  
       a second receptacle terminal disposed within the receptacle cavity; wherein,  
       a battery pack having front and rear ends and first and second pack terminals disposed adjacent the front end, said pack is slidably locatable in the receptacle cavity and is releasably secured in said cavity with the longitudinal axis of the battery pack coaxial to the longitudinal axis of the receptacle cavity and with the first receptacle terminal matable with the first pack terminal and the second receptacle terminal matable with the second pack terminal in any angular orientation of the pack about the coaxial longitudinal axes.  
     
     
       15. The device recited in claim  14 , wherein, said first receptacle terminal is spaced at a first radial distance from the longitudinal axis of the receptacle cavity, the second receptacle terminal is space at a second radial distance from the longitudinal axis of the receptacle cavity with the second radial distance being greater than the first radial distance, the battery pack has a casing having an overall radius which is substantially the same as the second radial distance, and the battery pack is locatable in the receptacle cavity with second receptacle terminal disposed in contact with an exterior surface of the casing.