Variable displacement metering pump system with multivariate feedback

Abstract

A metering pump system includes a variable displacement pump having an inlet and an outlet, a flow sensing valve fluidically connected to the outlet of the variable displacement pump, and an actuator mechanically coupled to a displacement mechanism of the variable displacement pump. The metering pump system also includes an electronic engine controller in communication with the flow sensing valve. An electrohydraulic servo valve is electrically connected to the electronic engine controller and hydraulically connected to the actuator. The electrohydraulic servo valve is configured to hydraulically drive the actuator to move the displacement mechanism to change displacement of the variable displacement pump.

1 . A metering pump system comprising:
 a variable displacement pump comprising an inlet and an outlet;   a flow sensing valve fluidically connected to the outlet of the variable displacement pump, wherein the flow sensing valve comprises:
 a resistance temperature detector configured to measure a temperature of flow through the flow sensing valve; and 
 a first linear variable differential transducer configured to measure a linear displacement of the flow sensing valve; 
   an actuator mechanically coupled to a displacement mechanism of the variable displacement pump, wherein the actuator comprises a second linear variable differential transducer configured to measure a linear displacement of the actuator;   an electronic engine controller in communication with the flow sensing valve wherein the electronic engine controller is configured to determine an actual flow rate of fuel through the flow sensing valve using the temperature of the fuel through the flow sensing valve and the linear displacement of the flow sensing valve and to determine a predicted flow rate of the fuel out of the variable displacement pump using the linear displacement of the actuator; and   an electrohydraulic servo valve electrically connected to the electronic engine controller and hydraulically connected to the actuator, wherein the electrohydraulic servo valve is configured to hydraulically drive the actuator to move the displacement mechanism to change displacement of the variable displacement pump.   
     
     
         2 . (canceled) 
     
     
         3 . The metering pump system of  claim 1 , wherein the actuator is a piston assembly comprising:
 a housing;   a piston cylinder inside the housing   a fluid chamber contained within the housing on a first side of the piston cylinder;   a spring chamber inside the housing and opposite the fluid chamber relative the piston cylinder; and   a piston rod attached to the piston cylinder.   
     
     
         4 . The metering pump system of  claim 3 , wherein the piston rod is operably connected to the displacement mechanism of the variable displacement pump. 
     
     
         5 . The metering pump system of  claim 4 , wherein the displacement mechanism is a swashplate. 
     
     
         6 . (canceled) 
     
     
         7 . The metering pump of  claim 1 , wherein the flow sensing valve, the electronic engine controller, and the linear variable differential transducer form a continuous positive feedback loop. 
     
     
         8 . The metering pump system of  claim 1 , wherein the actuator is a hydraulic actuator that uses fuel for a hydraulic fluid. 
     
     
         9 . A metering pump system comprising:
 a variable displacement pump comprising an inlet and an outlet;   an actuator mechanically coupled to the variable displacement pump;   a drive unit connected to the actuator;   an electronic engine controller electronically connected to the drive unit;   a first linear variable displacement transducer on the actuator and configured to measure a position of the actuator, wherein the linear variable displacement transducer is in communication with the electronic engine controller; and   a flow sensing valve fluidically connected to the outlet of the variable displacement pump, wherein the flow sensing valve comprises:
 a resistance temperature detector configured to measure a temperature of fuel flow in the flow sensing valve, wherein the resistance temperature detector is electrically connected to the electronic engine controller; and 
 a second linear variable displacement transducer configured to measure a linear displacement of the flow sensing valve, wherein the linear variable displacement transducer is electrically connected to the electronic engine controller; 
   wherein the electronic engine controller is configured to determine an actual flow rate of fuel through the flow sensing valve using the temperature of the fuel through the flow sensing valve and the linear displacement of the flow sensing valve and to determine a predicted flow rate of the fuel out of the variable displacement pump using the linear displacement of the actuator.   
     
     
         10 . The metering pump system of  claim 9 , wherein the drive unit comprises an electrohydraulic servo valve. 
     
     
         11 . The metering pump system of  claim 10 , wherein the actuator is a piston assembly hydraulically connected to the electrohydraulic servo valve. 
     
     
         12 . The metering pump system of  claim 11 , wherein the variable displacement pump comprises a displacement mechanism mechanically connected to the piston assembly. 
     
     
         13 . The metering pump system of  claim 12 , wherein the displacement mechanism is a swashplate. 
     
     
         14 . The metering pump system of  claim 13 , wherein the flow sensing valve, the electronic engine controller, and the linear variable differential transducer form a continuous positive feedback loop. 
     
     
         15 . A method of pumping in a system comprising:
 pumping fuel through the system with a variable displacement pump, wherein the variable displacement pump comprises a displacement mechanism mechanically connected to an actuator;   directing the fuel through a flow sensing valve connected to an outlet of the variable displacement pump;   sensing a temperature of the fuel flowing through the flow sensing valve via a resistance differential transducer;   sensing a linear displacement of the flow sensing valve via a first linear variable differential transducer;   communicating the temperature of the fuel flowing through the flow sensing valve and the linear displacement of the flow sensing valve to an electronic engine controller;   delivering an electrical current to a servo valve by the electronic engine controller;   moving the actuator with the servo valve to actuate the displacement mechanism of the variable displacement pump and alter displacement of the variable displacement pump;   sensing a linear displacement of the actuator with a second linear variable differential transducer;   communicating the linear displacement of the actuator to the electronic engine controller;   determining, with the electronic engine controller, an actual flow rate of fuel through the flow sensing valve using the temperature of the fuel through the flow sensing valve and the linear displacement of the flow sensing valve;   determining, with the electronic engine controller, a predicted flow rate of the fuel out of the variable displacement pump using the linear displacement of the actuator.   
     
     
         16 . (canceled) 
     
     
         17 . The method of  claim 15 , further comprising:
 comparing the actual flow rate of the fuel through the flow sensing valve with the predicted flow rate of the fuel out of the variable displacement pump to analyze performance of the variable displacement pump.   
     
     
         18 . The method of  claim 15 , wherein the displacement mechanism is a swashplate. 
     
     
         19 . The method of  claim 15 , wherein the servo valve is an electrohydraulic servo valve. 
     
     
         20 . The method of  claim 15 , wherein the actuator is a hydraulic actuator that uses fuel for a hydraulic fluid.