Automated two-blower cooking stove

Abstract

A two-blower automated biomass cooking stove with sensors that dynamically adjusts independent air flows and optimizes for the fresh fuel phase, but also manages air through a transitional phase, and then a char phase. The cookstove comprises a housing, a combustion assembly mounted within the housing; dual air flow passageways disposed at least partially within the housing for communicating air flow from outside the housing to a combustion cup, and a control system for automatically and dynamically adjusting relative air flow between the primary and secondary air flow passageways to optimize performance.

We claim: 
     
         1 . An automated two blower cooking stove comprising:
 a combustion chamber having primary air holes, secondary air holes, a combustion cup base, and a flame well, the secondary air holes disposed above the primary air holes, the combustion cup base adjacent the primary air holes, and the flame well disposed adjacent the secondary air holes,   a primary air flow passage in communication with the primary air holes,   a secondary air flow passage in communication with the secondary air holes,   a primary blower disposed to blow air into the primary air flow passage,   a secondary blower disposed to blow air into the secondary air flow passage,   a primary temperature sensor disposed near the primary air holes for measuring the temperature of the combustion cup base,   a secondary temperature sensor disposed near the secondary air holes for measuring the temperature of the flame well,   a controller in communication with said primary and secondary temperature sensors and with the primary and secondary blowers, the controller configured to:
 detect, using the primary temperature sensor, the rate of change of the temperature of the combustion cup base, 
 detect, using the secondary temperature sensor, that the temperature of the flame well is greater by a pre-established increment than the temperature of the combustion cup base, and if so: 
 adjust the speeds of the primary and secondary blowers to speeds indicated in a configuration file for a target flame level set by a potentiometer. 
   
     
     
         2 . The automated two blower cooking stove of  claim 1  further comprising:
 a housing, 
 an air jacket mounted inside the housing, 
 the combustion chamber suspended from the air jacket, 
 an air separator disposed between the air jacket and the combustion chamber, the space between the combustion chamber and the air separator defining the primary air flow passage, and the space between the air separator and the air jacket defining the secondary air flow passage. 
 
     
     
         3 . The automated two blower cooking stove of  claim 1  further comprising:
 the controller configured to:
 detect, using the primary temperature sensor, that the bottom combustion zone has reached a pre-established hot “CHARFLIP” temperature, and 
 adjust the speed of the secondary blower to increase the amount of air blowing into the secondary air flow passage to optimize combustion at the flame well. 
 
 
     
     
         4 . The automated two blower cooking stove of  claim 3  further comprising:
 the controller configured to:
 increase the speed of the primary blower in a plurality of steps by a first set of pre-established increments over a transition time, 
 increase the speed of the secondary blower serially after each of said plurality of steps by a second set of pre-established increments over said transition time, 
 detect that the temperature of the combustion cup base has reached a pre-established “CHARMAX” temperature, or that said transition time has expired, and if so: 
 terminate the increases of speeds of the primary and secondary blowers. 
 
 
     
     
         5 . The automated two blower cooking stove of  claim 3  further comprising:
 the controller configured to:
 detect that the temperature of the flame well has fallen below a pre-established shutdown temperature, and if so 
 turn off the primary and secondary blowers. 
 
 
     
     
         6 . The automated two blower cooking stove of  claim 1  further comprising:
 the controller configured to:
 determine if the current speeds of the primary and secondary blowers are at pre-established speeds indicated in a configuration file for a target flame level set by a potentiometer, and if so 
 increase or decrease the speeds of the primary and secondary blowers until said current speeds meet the speeds indicated by said target flame level. 
 
 
     
     
         7 . The automated two blower cooking stove of  claim 6  further comprising:
 the controller configured to:
 determine that current speeds are lower than the speeds indicated by said target flame level, 
 increase the speed of the secondary blower in a plurality of steps by a first set of pre-established increments, and 
 increase the speed of the primary blower serially after each of said plurality of steps by a second set of pre-established increments. 
 
 
     
     
         8 . The automated two blower cooking stove of  claim 6  further comprising:
 the controller configured to:
 determine that current speeds are higher than the speeds indicated by said target flame level, and if so 
 decrease the speed of the secondary blower in a plurality of steps by a first set of pre-established increments, and 
 decrease the speed of the primary blower serially after each of said plurality of steps by a second set of pre-established increments. 
 
 
     
     
         9 . The automated two blower cooking stove of  claim 1  further comprising:
 the controller configured to:
 determine that the temperature of the flame well is less by a pre-established increment than the temperature of the combustion cup base, and if so:
 set the speeds of the primary and secondary air blowers at a pre-established level, and 
 
 determine after a pre-established Time-Startup time interval has elapsed that the temperature of the flame well is greater than a pre-established shutdown reference temperature, and if so:
 increase the speeds of the primary and secondary blowers to speeds indicated in a configuration file for a target flame level set by a potentiometer. 
 
 
 
     
     
         10 . An automated two blower cooking stove comprising:
 a combustion chamber having primary air holes, secondary air holes, a combustion cup base and a flame well, the secondary air holes disposed above the primary air holes, the combustion cup base adjacent the primary air holes, and the flame well disposed adjacent the secondary air holes,   a primary air flow passage in communication with the primary air holes,   a secondary air flow passage in communication with the secondary air holes,   a primary blower disposed to blow air into the primary air flow passage,   a secondary blower disposed to blow air into the secondary air flow passage,   a primary temperature sensor disposed near the primary air holes for measuring the temperature of the combustion cup base,   a secondary temperature sensor disposed near the secondary air holes for measuring the temperature of the flame well,   a controller in communication with said primary and secondary temperature sensors and with the primary and secondary blowers, the controller configured to:
 detect, using the primary temperature sensor, the temperature of the combustion cup base, p 2  detect, using the secondary temperature sensor, that the flame well is greater by a pre-established increment than the temperature of the combustion cup base, and if so: 
 increase the speeds of the primary and secondary blowers to speeds indicated in a configuration file for a target flame level set by a potentiometer, and 
   detect that the temperature of the flame well is less by a pre-established increment than the temperature of the combustion cup base, and if so:
 set the speeds of the primary and secondary air blowers at a pre-established level, 
 determine after a pre-established time interval has elapsed that the temperature of the flame well is greater than a pre-established reference temperature, and if so
 increasing the speeds of the primary and secondary blowers to speeds indicated in a configuration file for a target flame level set by a potentiometer. 
 
   
     
     
         11 . An automated two blower cooking stove comprising:
 a combustion cup for mounting in a housing, the combustion cup having an inside face and an interior cavity, combustion cup air holes and an inwardly extending peripheral shelf, the air holes disposed above the shelf, a diffuser having a central dome, a peripheral lip and a sloped upturned flange, said peripheral lip extending outwardly from said outer dome, said peripheral lip having   diffuser air holes, said upturned flange extending from an outer edge of said peripheral lip, said upturned flange sized to fit closely within said inside face, said central dome, peripheral lip and upturned flange defining a flame well,   in an assembled configuration, said diffuser removably inserted in said combustion cup, said peripheral lip supported by said peripheral shelf, said diffuser air holes in communication with said interior cavity, said peripheral lip disposed below said combustion cup air holes, said combustion cup air holes and said diffuser air holes in communication with said flame well.   
     
     
         12 . The automated two blower cooking stove of  claim 11  further comprising:
 a skid plate, said skid plate having cooling air holes, 
 a housing mounted on said skid plate, an upper edge of said housing having ventilation slots, 
 said combustion cup disposed in said housing, 
 a lid mounted on said housing, 
 an air gap defined between said combustion cup and said housing, said air gap in communication with said cooling air holes and said ventilation slots creating a passive air-cooling system for insulating the housing against heat emanating from the combustion cup. 
 
     
     
         13 . A high efficiency automated low emission biomass cookstove comprising:
 a housing,   a combustion assembly inside the housing,   dual air flow passageways disposed at least partially within the housing for communicating air flow from outside the housing to said combustion assembly, and   a control system for automatically and dynamically adjusting relative air flow between said primary and secondary air flow passageways.