Ignition control system and method

Abstract

The invention is directed to an ignition control system that dynamically adjusts the warm-up time of an igniter within a predetermined range depending on the success or failure of the previous ignition or start-up cycle. The system activates the igniter and waits a predetermined or computed warm-up time. At the end of the warm-up time, the system opens a gas valve. The system then waits a preset time from the opening of the gas valve to determine whether ignition was successful or not. If the ignition was successful, the system computes a new igniter warm-up time by decrementing the current time and stores this new value for use during the next start sequence. If the ignition was unsuccessful, the system computes a new warm-up time by incrementing the current value and retrying the start sequence. Preferably, a successful ignition is always determined by checking for the presence of flame a fixed time following the opening of the gas valve.

What is claimed is:  
     
         1 . An ignition control system for use in attempting to start a fuel operated device, the ignition control system comprising: 
 a burner;    a fuel valve moveable between an open position and a closed position for selectively providing fuel to the burner;    an igniter for igniting a fuel from the burner;    a flame sensor configured and arranged to issue a signal indicative of the presence or absence of flame at the burner; and    a controller operatively coupled to the igniter and the fuel valve, and in communicating relationship with the flame sensor, wherein 
 the controller activates the igniter for a predetermined warm-up time,  
 at the end of the predetermined warm-up time, the controller moves the fuel valve to the open position,  
 after a first preset time following the opening of the fuel valve, the controller deactivates the igniter,  
 after a second preset time following the opening of the fuel valve, the controller checks the flame sensor signal to see whether or not flame is present, thereby indicating a successful or an unsuccessful ignition, and  
 if the ignition was successful, the controller decrements the igniter warm-up time during the next start and, if the ignition was unsuccessful, the controller increments the igniter warm-up time and tries to start the device again.  
   
     
     
         2 . The ignition control system of  claim 1  wherein the igniter warm-up time is decremented to a minimum warm-up time and incremented to a maximum warm-up time.  
     
     
         3 . The ignition control system of  claim 2  wherein 
 the minimum warm-up time is one of approximately six and 12 seconds, and  
 the maximum warm-up time is one of approximately 36 and 54 seconds.  
 
     
     
         4 . The ignition control system of  claim 1  wherein the second preset time is approximately five seconds.  
     
     
         5 . The ignition control system of  claim 1  wherein the controller includes a microprocessor and a programmable memory device.  
     
     
         6 . The ignition control system of  claim 1  wherein the warm-up time is incremented and decremented in steps of one of approximately three, six, 12 and 24 seconds each.  
     
     
         7 . The ignition control system of  claim 1  wherein, after an unsuccessful ignition followed by a successful retry attempt, the controller performs subsequent ignitions using the warm-up time of the successful retry attempt.  
     
     
         8 . The ignition control system of  claim 7  wherein the controller performs a preset number of subsequently successful ignitions before decrementing the warm-up time.  
     
     
         9 . The ignition control system of  claim 8  wherein the preset number is approximately 250.  
     
     
         10 . The ignition control system of  claim 1  wherein the fuel is one of natural gas and propane.  
     
     
         11 . The ignition control system of  claim 1  wherein the device is one of a furnace and an appliance.  
     
     
         12 . An method for use in attempting to start a fuel operated device having a burner, a fuel valve moveable between an open and a closed position for selectively providing fuel to the burner, an igniter for igniting a fuel from the burner, and a flame sensor configured and arranged to issue a signal indicative of the presence or absence of flame at the burner, the ignition method comprising the steps of: 
 activating the igniter for a predetermined warm-up time;    moving the fuel valve to the open position at the end of the predetermined warm-up time;    deactivating the igniter after a first preset time following the opening of the fuel valve;    checking the flame sensor signal to see whether or not flame is present, thereby indicating a successful or an unsuccessful ignition, after a second preset time following the opening of the fuel valve;    if the ignition was successful, decrementing the igniter warm-up time during the next start; and    if the ignition was unsuccessful, incrementing the igniter warm-up time and trying to start the device again.    
     
     
         13 . The method of  claim 12  further comprising the steps of: 
 blocking the igniter warm-up time from being decremented below a minimum warm-up time; and  
 blocking the igniter warm-up time from being incremented above a maximum warm-up time.  
 
     
     
         14 . The method of  claim 12  further comprising the step entering a lock-out state following a set number of unsuccessful ignition attempts whereby further attempts at ignition are suspended while in the lock-out state.  
     
     
         15 . The method of  claim 13  further comprising the steps of: 
 following a successful retry after an unsuccessful ignition attempt, utilizing the last computed igniter warm-up for one or more subsequent ignition attempts.  
 
     
     
         16 . The method of  claim 15  further comprising the steps of: 
 after an unsuccessful ignition attempt, determining whether there have been a fixed number of consecutive successful ignitions, and  
 if so, decrementing the igniter warm-up time during the next ignition attempt.  
 
     
     
         17 . The method of  claim 16  wherein the fixed number is approximately 250.  
     
     
         18 . The method of  claim 12  wherein the igniter warm-up time is incremented and decremented in steps of one of approximately three, six, 12 and 24 seconds each.  
     
     
         19 . The method of  claim 13  wherein 
 the minimum warm-up time is one of approximately six and 12 seconds, and  
 the maximum warm-up time is one of approximately 36 and 54 seconds.