Means and arrangement for fuel icing protection

Abstract

A fuel delivery system comprises a pump, a fuel metering device located downstream of the pump, and a fuel spill loop from the fuel metering device to a discharge point at a location upstream of the pump. The fuel metering device regulates the fuel flow to a combustor and directs surplus fuel delivered by the pump through the fuel spill loop. The system further includes a means for controlling one or more of the pressure and volume of the fuel flow delivered to the fuel metering device independently of the engine operating conditions to thereby control the temperature of the fuel.

What is claimed is: 
     
         1 . A fuel delivery system comprising a pump, a fuel metering device located downstream of the pump, and a fuel spill loop from the fuel metering device to a discharge point at a location upstream of the pump; wherein the fuel metering device regulates the fuel flow to a combustor and directs surplus fuel delivered by the pump through the fuel spill loop, and wherein means are provided for controlling one or more of the pressure and volume of the fuel flow delivered to the fuel metering device independently of the engine operating conditions. 
     
     
         2 . The fuel delivery system as claimed in  claim 1 , wherein the pump comprises a variable capacity pump to control the volume of fuel delivered to the fuel metering device. 
     
     
         3 . The fuel delivery system as claimed in  claim 1 , further comprising a variable flow restrictor to control the pressure of the fuel flow delivered to the fuel metering device. 
     
     
         4 . The fuel delivery system as claimed in  claim 3 , wherein the variable flow restrictor is located downstream of the pump. 
     
     
         5 . The fuel delivery system as claimed in  claim 3 , wherein the variable flow restrictor is integral with the pump. 
     
     
         6 . The fuel delivery system as claimed in  claim 1 , further comprising a filter located upstream of the pump, wherein the discharge point of the fuel spill loop is at a location upstream of the filter. 
     
     
         7 . The fuel delivery system as claimed in  claim 1 , further comprising a heat exchanger located upstream of the pump, wherein the discharge point of the fuel spill loop is at a location upstream of the heat exchanger. 
     
     
         7 . fuel delivery system as claimed in  claim 7 , wherein the heat exchanger is a fuel and oil heat exchanger. 
     
     
         9 . The fuel delivery system as claimed in  claim 1 , wherein the discharge point of the fuel spill loop is at a location immediately upstream of the heat exchanger. 
     
     
         1 . fuel delivery system as claimed in  claim 1 , wherein a the fuel spill loop comprises a plurality of discharge points, and wherein means are provided for selecting one of said plurality of discharge points. 
     
     
         11 . The fuel delivery system as claimed in  claim 1 , further comprising a temperature sensor for sensing the temperature of the fuel. 
     
     
         11 . fuel delivery system as claimed in  claim 11 , wherein a plurality of temperature sensors are provided at spaced locations within the system. 
     
     
         13 . A method of controlling the temperature of fuel in a fuel delivery system, the method comprising controlling one or more of the pressure and volume of fuel flow delivered to a fuel metering device independently of the engine operating conditions. 
     
     
         14 . The method as claimed in  claim 13 , wherein both the pressure and the volume of the fuel flow are controlled. 
     
     
         15 . The method as claimed in  claim 13 , wherein the pressure of the fuel flow is controlled based on the temperature of the fuel in the system. 
     
     
         16 . The method as claimed in  claim 13 , wherein the volume of the fuel flow is controlled based on the temperature of the fuel in the system. 
     
     
         17 . The method as claimed in  claim 13 , wherein the fuel delivery system comprises a pump, a fuel metering device located downstream of the pump, and a fuel spill loop from the fuel metering device to a discharge point at a location upstream of the pump;
 wherein the fuel metering device regulates the fuel flow to a combustor and directs surplus fuel delivered by the pump through the fuel spill loop, and   wherein means are provided for controlling one or more of the pressure and volume of the fuel flow delivered to the fuel metering device independently of the engine operating conditions.   
     
     
         18 . The method of increasing the temperature of fuel in a fuel delivery system as claimed in  claim 13 . 
     
     
         19 . The method of decreasing the temperature of fuel in a fuel delivery system as claimed in  claim 13 .