Flow sensing dual pump switching system and method

摘要

A flow sensing dual pump switching system and method are provided that control the supply of fuel from a dual pump fuel system to a fuel metering unit. The system senses bypass pressure from the fuel metering unit to control the differential pressurization of the second pump. As the bypass is reduced, the pressure of the second pump is increased so that it may be added to that of the first pump to supply the increased fuel consumption needs of an engine. As the fuel consumption needs decrease, the flow from the second pump added to the first pump is reduced and the differential pressure of the second pump is similarly reduced. If the bypass pressure remains high, the switching system disconnects the output of the second pump from that of the first in favor of bypassing the flow to its input to reduce its differential pressure and conserve energy.

主权项

1. A switching system for use with a dual pump fuel supply system for an aircraft engine, the dual pump fuel supply system including a first pump having a first high pressure output coupled to a high pressure supply to a fuel metering unit, wherein the fuel metering unit is configured to supply a portion of the fuel supply to an engine and to return a bypass flow of the fuel supply to a low pressure return that is coupled to a first low pressure supply to the first pump, and a second pump having a second high pressure output and a second low pressure supply that is coupled to the low pressure return, the second pump also having a second pump bypass that is coupled to the second low pressure supply, comprising:
means for sensing the bypass flow coming directly from the fuel metering unit; means, operatively coupled to the means for sensing the bypass flow coming directly from the fuel metering unit, for controlling a pressurization of the second pump; and means for adding or subtracting the second high pressure output from the second pump to the first high pressure output from the first pump, wherein said means for adding are downstream from the first and second high pressure outputs and upstream from the fuel metering unit.