Vehicle heater and controls therefor

Abstract

A heater for a liquid has a combustion chamber, a jacket for the liquid extending about the combustion chamber and a burner head assembly connected to the combustion chamber. The burner head assembly includes a housing having a burner mounted thereon and a hollow interior. A control module and a fan are mounted in the hollow interior, the fan being connected to an electric motor. A compressor and a fuel pump are mounted on the housing and are operatively connected to the electric motor. The control module may include controls for exercising components of the heater prior to combustion, thereby verifying operation of these components. Preferably there is a speed control for the motor, such as a closed loop speed control which regulates motor speed and accordingly output of the heater. Preferably there is a backup system using a lookup table in the event that the closed loop speed control fails. Also preferably there is provision for monitoring flame sensor functionality by providing an indicator light which mirrors operation of the flame sensor. The heater may have a selective soft start for the coolant pump which operates only when required so as to reduce unnecessary chatter on the motor relay. A system is also provided for distinguishing true overcurrent faults from overcurrents arising from voltage changes during starting of the vehicle engine. Reignition algorithms are provided to restart the burner in the event of flame sputters caused, for example, by fuel bubbles, but shut off the heater in the event that the fuel is truly cut off.

1 - 33 . (cancelled)  
     
     
         34 . A method for determining whether a fault has occurred in a device having a fuel burning with a flame and an ignitor for igniting the flame, the method comprising the steps of: 
 sensing periodically whether or not a flame is present;    registering a flame on event if the flame is present;    actuating the ignitor if no flame is present;    registering a flame out event if no flame is present after the ignitor is actuated; and    indicating that a fault has occurred when a first plurality of flame out events occurs before a second plurality of flame on events occurs.    
     
     
         35 . The method as claimed in  claim 34 , wherein the method is repeated cyclically, a new cycle beginning when the second plurality of flame on events occurs before the first plurality of flame out events occurs.  
     
     
         36 . The method as claimed in  claim 35 , wherein the presence of a flame is sensed once per second plurality.  
     
     
         37 . The method as claimed in  claim 36 , wherein the first plurality is 10 and the second plurality is 15.  
     
     
         38 . An apparatus for determining whether a fault has occurred in a device having a fuel burning with a flame and an ignitor for igniting the flame, the apparatus comprising: 
 a flame sensor which periodically senses whether or not a flame is present;    a first memory which stores a flame on event if the flame is present;    means for actuating the ignitor if no flame is present;    a second memory which stores a flame out event if no flame is present after the ignitor is actuated; and    a control device which indicates that a fault has occurred when a first plurality of flame out events occurs before a second plurality of flame on events occurs.    
     
     
         39 . The apparatus as claimed in  claim 38 , wherein the sensor senses for a flame cyclically, a new cycle beginning when the second plurality of flame on events occurs before the first plurality of flame out events occurs.  
     
     
         40 . The apparatus as claimed in  claim 39 , wherein the presence of a flame is sensed once per second  
     
     
         41 . The apparatus as claimed in  claim 39 , wherein the first plurality is 10 and the second plurality is 15.  
     
     
         42 - 45 . (cancelled)