Means for measuring the liquid level in a reservoir for a fuel cell

Abstract

A small fuel cell ( 10 ) powers a portable electronic device ( 12 ) and contains a fuel reservoir ( 14 ) and a device ( 16 ) that measures the amount of liquid fuel ( 18 ) that is in the reservoir. The fuel cell operates on hydrogen that is obtained from a liquid hydrocarbon fuel, such as alcohol or other hydrocarbons. The liquid fuel is typically converted into hydrogen by a reforming process. The reservoir that is connected to the fuel cell has an indicia ( 19 ) that is readable by a human user of the portable electronic device, for measuring the amount of liquid hydrocarbon fuel that is present in the reservoir. Typically, the indicia consist of a sight glass, a capacitive element, a resistive element, a transparent portion of the reservoir, a float, or an acoustic transmitter coupled with an acoustic receiver.

What is claimed is:  
     
         1 . A fuel cell system for a portable electronic device, comprising: 
 a fuel cell capable of operating on hydrogen that is obtained from methanol;    a reservoir for storing a supply of methanol, suitably connected to the fuel cell; and    the reservoir further comprising a fuel quantity measuring means.    
     
     
         2 . The fuel cell as described in  claim 1 , wherein the fuel quantity measuring means comprises a sight glass.  
     
     
         3 . The fuel cell as described in  claim 1 , wherein the fuel quantity measuring means comprises a float.  
     
     
         4 . The fuel cell as described in  claim 1 , wherein the fuel quantity measuring means comprises a transparent reservoir.  
     
     
         5 . The fuel cell as described in  claim 1 , wherein the fuel quantity measuring means comprises a resistive element.  
     
     
         6 . The fuel cell as described in  claim 1 , wherein the fuel quantity measuring means comprises a capacitive element.  
     
     
         7 . The fuel cell as described in  claim 1 , wherein the fuel quantity measuring means comprises an acoustic transmitter and an acoustic receiver.  
     
     
         8 . A fuel cell system for a portable electronic device, comprising: 
 a fuel cell that operates on hydrogen obtained from a liquid hydrocarbon fuel;    a reservoir for containing a supply of the liquid hydrocarbon fuel, said reservoir connected to the fuel cell; and    the reservoir further comprising an indicia readable by a human user of the portable electronic device, for measuring the amount of liquid hydrocarbon fuel that is present in the reservoir.    
     
     
         9 . The fuel cell as described in  claim 8 , wherein the indicia comprises a sight glass.  
     
     
         10 . The fuel cell as described in  claim 8 , wherein the indicia comprises a float.  
     
     
         11 . The fuel cell as described in  claim 8 , wherein the indicia comprises a transparent reservoir.  
     
     
         12 . The fuel cell as described in  claim 8 , wherein the indicia further comprises a sensing means.  
     
     
         13 . The fuel cell as described in  claim 12 , wherein the sensing means comprises a resistive element.  
     
     
         14 . The fuel cell as described in  claim 12 , wherein the sensing means comprises a capacitive element.  
     
     
         15 . The fuel cell as described in  claim 12 , wherein the sensing means comprises an acoustic transmitter and an acoustic receiver.  
     
     
         16 . The fuel cell system as described in  claim 8 , wherein the indicia comprises a liquid crystal display.  
     
     
         17 . A fuel cell system for powering a portable electronic device, comprising: 
 a portable electronic device having a radio transmitter and a radio receiver;    a fuel cell electrically and mechanically coupled to said portable electronic device, said fuel cell capable of operating on hydrogen that is obtained from methanol;    a reservoir for storing a supply of methanol, suitably connected to the fuel cell; and    the reservoir further comprising a fuel quantity measuring means.    
     
     
         18 . The fuel cell system as described in  claim 17 , wherein the fuel quantity measuring means comprises a liquid crystal display in the portable electronic device.  
     
     
         19 . The fuel cell system as described in  claim 17 , wherein the fuel quantity measuring means comprises a liquid crystal display disposed on the fuel cell.