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 - 27 . (cancelled)  
     
     
         28 . A method of differentiating overcurrent faults from normal current conditions in an apparatus intended to be mounted to a vehicle and connected to the electrical system thereof, the method comprising monitoring for an overcurrent condition, monitoring voltage levels and determining whether there is a decrease in voltage relative to time exceeding a first specified value of dV/dT, or whether there is an increase in voltage relative to time exceeding a second specified value of dV/dT, declaring no overcurrent fault where there is said decrease in voltage exceeding the first specified value within a first specified time prior to an overcurrent condition or if there is an increase in voltage exceeding the second specified value within a second specified time of the overcurrent condition, and declaring an overcurrent fault where there is an overcurrent condition, but no such decrease in voltage or increase in voltage within the specified times.  
     
     
         29 . The method as claimed in claimed  28  wherein the apparatus is a heater and the method differentiates overcurrent events resulting from the vehicle being started from overcurrent events indicating a fault.  
     
     
         30 . An apparatus for differentiating overcurrent faults from normal current conditions in a device intended to be mounted to a vehicle and connected to the electrical system thereof, the apparatus comprising controls which monitor for overcurrent conditions, monitor voltage levels and determine whether there is a decrease in voltage relative to time exceeding a first specified value of dV/dT, or whether there is an increase in voltage relative to time exceeding a second specified value of dV/dT, declaring no overcurrent fault where there is said decrease in voltage exceeding the first specified value within a first specified time prior to an overcurrent condition or if there is an increase in voltage exceeding the second specified value within a second specified time of the overcurrent condition, and declaring an overcurrent fault where there is no such decrease in voltage or increase in voltage within the specified times.  
     
     
         31 . The apparatus as claimed in  claim 30  wherein the device is a heater and the controls differentiate overcurrent events resulting from the vehicle being started from overcurrent events indicating a fault.  
     
     
         32 - 45 . (cancelled)