Fluid Delivery System and Method

Abstract

A fluid delivery system includes a reservoir, a pump, an injector, and a pressure regulator. The reservoir encloses a fluid and includes a reservoir body forming a reservoir volume that encloses the fluid. The reservoir includes a draw conduit and a return conduit. The pump has an inlet connected to the draw conduit and provides fluid at the operating pressure and at a desired flow to a pressure line that is fluidly connected to an outlet of the pump. The injector selectively opens to allow an injected fluid flow to pass therethrough. The return orifice fluidly connects the pressure line with the return conduit, and the pressure regulator provides a regulated fluid flow to the fluid reservoir. During operation, the desired fluid flow is equal to a sum of the injected fluid flow, the return fluid flow and the regulated fluid flow.

We claim: 
     
         1 . A fluid delivery system, comprising:
 a fluid reservoir adapted to enclose a fluid therewithin, the fluid reservoir comprising a reservoir body forming a reservoir volume that encloses the fluid therewithin and that includes a fluid draw conduit, which is configured to draw fluid from the reservoir volume, and a fluid return conduit, which is configured to return fluid to the reservoir volume;   a pump having an inlet fluidly connected to the fluid draw conduit such that the pump can draw fluid from the fluid reservoir, increase a pressure of the fluid to an operating pressure, and provide fluid at the operating pressure and at a desired fluid flow to a pressure line that is fluidly connected to an outlet of the pump;   a fluid injector fluidly in communication with the pressure line, the fluid injector configured to selectively open and allow pressurized fluid at a predetermined, injected fluid flow to pass therethrough when the fluid injector is open; and   a pressure regulator having a regulator inlet in fluid communication with the pressure line and a regulator outlet in fluid communication with the fluid return conduit, the pressure regulator configured to provide a regulated fluid flow to the fluid reservoir when the operating pressure exceeds a pressure regulator opening pressure;   wherein, during operation, the desired fluid flow is equal to a sum of the injected fluid flow and the regulated fluid flow.   
     
     
         2 . The fluid delivery system of  claim 1 , further comprising:
 a pressure sensor disposed in fluid communication with the pressure line and configured to measure a fluid pressure within the pressure line and provide a pressure signal; and   an electronic controller disposed to receive the pressure signal.   
     
     
         3 . The fluid delivery system of  claim 2 , wherein the pump is a fixed displacement pump that is operated by a variable speed motor, the variable speed motor being responsive to a command signal provided by the electronic controller based, at least in part, on the pressure signal. 
     
     
         4 . The fluid delivery system of  claim 3 , wherein the command signal provided by the electronic controller uses environmental variables as primary control parameters to determine the command signal that will provide the desired fluid flow to the pressure line. 
     
     
         5 . The fluid delivery system of  claim 4 , wherein the environmental variables include ambient temperature, fluid temperature, and altitude. 
     
     
         6 . The fluid delivery system of  claim 3 , wherein the electronic controller includes an integrator function that provides a compensation factor based on a difference between a desired pressure and the operating pressure, said compensation factor having a long term. 
     
     
         7 . The fluid delivery system of  claim 2 , wherein the motor has a fixed speed and the pump has a variable displacement such that the pump is a variable displacement pump, the variable displacement pump being responsive to a command signal provided by the electronic controller based, at least in part, on the pressure signal. 
     
     
         8 . The fluid delivery system of  claim 7 , wherein the command signal provided by the electronic controller uses environmental variables as primary control parameters to determine the command signal that will provide the desired fluid flow to the pressure line. 
     
     
         9 . The fluid delivery system of  claim 1 , further comprising a return orifice fluidly connecting the pressure line at a location downstream of the fluid injector with the fluid return conduit such that a return fluid flow is returned to the fluid reservoir, wherein, during operation, the desired fluid flow is equal to a sum of the injected fluid flow, the return fluid flow and the regulated fluid flow. 
     
     
         10 . The fluid delivery system of  claim 7 , wherein the electronic controller includes an integrator function that provides a compensation factor based on a difference between a desired pressure and the operating pressure, said compensation factor having a long term. 
     
     
         11 . The fluid delivery system of  claim 1 , wherein the pressure line is part of a fluid flow circuit that includes a pressure junction disposed between the pressure regulator and the fluid injector such that the pressure regulator is disposed in parallel circuit connection with the return orifice between the pressure junction and the fluid reservoir. 
     
     
         12 . The fluid delivery system of  claim 1 , wherein the pressure regulator includes a valve element that is biased in a closed position by a spring, and wherein the spring is selected to have a spring constant that enables the valve element to open and fluid connect the pressure line with the reservoir when a pressure of fluid upstream of the valve element exceeds a force applied on the valve element by the spring. 
     
     
         13 . An exhaust after-treatment system for a machine, comprising:
 a diesel exhaust fluid (DEF) container adapted to enclose a DEF fluid therewithin, the DEF container comprising a reservoir body forming a reservoir volume that encloses the DEF and that includes a DEF draw conduit, which is configured to draw DEF from the reservoir volume, and a DEF return conduit, which is configured to return DEF to the reservoir volume;   a DEF injector configured to inject DEF from the container into an exhaust passage of an engine;   a pump having an inlet fluidly connected to the DEF draw conduit such that the pump can draw DEF from the container and provide it at an operating pressure to the DEF injector through a pressure line;   a return line configured to return unused DEF from the DEF injector to the DEF container; and   a pressure regulator configured to maintain a fluid pressure of the DEF provided to the DEF injector substantially constant by continuously shunting DEF from an outlet of the DEF pump to the DEF container;   wherein, during operation, a DEF flow provided by the pump is equal to a DEF flow injected by the DEF injector, a second DEF flow returned to the DEF container, and a third DEF flow shunted to the DEF container by the pressure regulator.   
     
     
         14 . The exhaust after-treatment system for a machine of  claim 1 , further comprising:
 a pressure sensor disposed in fluid communication with the pressure line and configured to measure a DEF pressure within the pressure line and provide a pressure signal; and   an electronic controller disposed to receive the pressure signal.   
     
     
         15 . The exhaust after-treatment system for a machine of  claim 14 , wherein the pump has a fixed displacement and is operated by a variable speed motor, the variable speed motor being responsive to a command signal provided by the electronic controller based, at least in part, on the pressure signal, wherein the command signal provided by the electronic controller uses environmental variables as primary control parameters to determine the command signal that will provide the desired fluid flow to the pressure line, and wherein the environmental variables include ambient temperature, fluid temperature, and altitude. 
     
     
         16 . The exhaust after-treatment system for a machine of  claim 15 , wherein the electronic controller includes an integrator function that provides a compensation factor based on a difference between a desired pressure and the operating pressure, said compensation factor having a long term. 
     
     
         17 . The exhaust after-treatment system for a machine of  claim 14 , wherein the motor has a fixed speed and the pump has a variable displacement such that the pump is a variable displacement pump, the variable displacement pump being responsive to a command signal provided by the electronic controller based, at least in part, on the pressure signal, wherein the command signal provided by the electronic controller uses environmental variables as primary control parameters to determine the command signal that will provide the desired fluid flow to the pressure line, and wherein the environmental variables include ambient temperature, fluid temperature, and altitude. 
     
     
         18 . The exhaust after-treatment system for a machine of  claim 17 , wherein the electronic controller includes an integrator function that provides a compensation factor based on a difference between a desired pressure and the operating pressure, said compensation factor having a long term. 
     
     
         19 . The exhaust after-treatment system for a machine of  claim 14 , wherein the pressure line is part of a fluid flow circuit that includes a pressure junction disposed between the pressure regulator and the return orifice such that the pressure regulator is disposed in parallel circuit connection with the return orifice between the pressure junction and the fluid reservoir. 
     
     
         20 . A method for operating a fluid system, comprising:
 drawing fluid from a reservoir with a pump;   pressurizing the fluid with the pump to provide a desired flow to a pressure line;   circulating a return flow of fluid from the pressure line back to the reservoir through a return orifice continuously during operation;   selectively injecting an injected flow of fluid from the pressure line through a fluid injector;   shunting a regulated flow of fluid of fluid from the pressure line, and returning the regulated flow back to the reservoir continuously during operation; and   adjusting, over a long term, the desired flow by comparing a pressure of fluid in the pressure line with a desired pressure;   selecting, based on environmental variables, the desired flow and selectively setting the same by appropriately commanding the pump;   wherein, at all times during operation, the desired flow is equal to the sum of the return flow, the injected flow, and the regulated flow.