Reductant dosing system with calibration value determined based on data from pressure sensor assembly and method of calibrating a reductant dosing system

Abstract

A reductant dosing system includes an injector, a fixed displacement pump in fluid communication with the injector, a reductant source in fluid communication with the fixed displacement pump, a pressure sensor assembly that detects a pressure of a reductant and stores a calibration value, and a controller communicatively coupled to the fixed displacement pump and the pressure sensor assembly. The controller receives data that includes the detected pressure of the reductant and the calibration value. The controller, in response to the calibration value being within a predetermined calibration value range, calculates a flow rate of the fixed displacement pump based on at least the detected pressure and the calibration value, and, in response to the calibration value being outside the predetermined calibration value range, calculates the flow rate of the fixed displacement pump based on at least the detected pressure and a pre-determined calibration value different from the calibration value.

What is claimed is: 
     
         1 . A reductant dosing system comprising:
 an injector;   a fixed displacement pump in fluid communication with the injector;   a reductant source in fluid communication with the fixed displacement pump;   a pressure sensor assembly configured to detect a pressure of a reductant in the reductant dosing system, and to store a calibration value of the fixed displacement pump; and   a controller communicatively coupled to the fixed displacement pump and to the pressure sensor assembly, wherein the controller is configured to:   receive, from the pressure sensor assembly, data that includes the detected pressure of the reductant and the calibration value,   in response to the calibration value being within a predetermined calibration value range, calculate a flow rate of the fixed displacement pump based on at least the detected pressure and the calibration value, and   in response to the calibration value being outside the predetermined calibration value range, calculate the flow rate of the fixed displacement pump based on at least the detected pressure and a pre-determined calibration value different from the calibration value.   
     
     
         2 . The reductant dosing system of  claim 1 , wherein:
 the data received from the pressure sensor assembly further includes a bit stream; and   the controller is further configured to, in response to determining that the bit stream has a start sequence different from a predetermined start sequence, determine the calibration value is faulty and calculate the flow rate of the fixed displacement pump based on at least the detected pressure and the pre-determined calibration value.   
     
     
         3 . The reductant dosing system of  claim 2 , wherein:
 the start sequence starts at a first start time and ends at a first end time, the start sequence having a steady voltage from the first start time to the first end time; and   the predetermined start sequence starts at a second start time and ends at a second end time, the predetermined start sequence having a non-steady voltage from the second start time to the second end time.   
     
     
         4 . The reductant dosing system of  claim 3 , wherein a voltage value of the predetermined start sequence at the second start time is equal to a voltage value of the predetermined start sequence at the second end time. 
     
     
         5 . The reductant dosing system of  claim 1 , wherein:
 the data received from the pressure sensor assembly further includes a bit stream; and   the controller is further configured to, in response to determining that the bit stream has a start sequence similar to a predetermined start sequence, determine the calibration value is not faulty and calculate the flow rate of the fixed displacement pump based on at least the detected pressure and the calibration value.   
     
     
         6 . The reductant dosing system of  claim 1 , wherein the calibration value comprises a frequency value associated with a fixed pressure. 
     
     
         7 . The reductant dosing system of  claim 1 , wherein the calibration value comprises a pressure differential value associated with a fixed frequency. 
     
     
         8 . The reductant dosing system of  claim 1 , wherein the calibration value is an offset at zero pump pressure when the fixed displacement pump is inactive. 
     
     
         9 . The reductant dosing system of  claim 8 , wherein the calibration value is the offset at the zero pump pressure when power is first applied to the reductant dosing system. 
     
     
         10 . The reductant dosing system of  claim 9 , wherein the controller is configured to compensate for the offset at the zero pump pressure while operating the fixed displacement pump. 
     
     
         11 . A method of calibrating a reductant dosing system, the method comprising:
 detecting, by a pressure sensor assembly, a pressure of a reductant in the reductant dosing system;   receiving, by a controller from the pressure sensor assembly, data that includes the detected pressure of the reductant and a calibration value;   in response to the calibration value being within a predetermined calibration value range, operating, by the controller, a fixed displacement pump based on at least the detected pressure of the reductant and the calibration value; and   in response to the calibration value being outside the predetermined calibration value range, operating, by the controller, the fixed displacement pump based on at least the detected pressure and a pre-determined calibration value different from the calibration value.   
     
     
         12 . The method of  claim 11 , wherein:
 the data received from the pressure sensor assembly further includes a bit stream; and   the method further comprises, in response to determining the bit stream having a start sequence different from a predetermined start sequence, determining, by the controller, the calibration value is faulty and operating, by the controller, the fixed displacement pump based on at least the detected pressure and the pre-determined calibration value.   
     
     
         13 . The method of  claim 12 , wherein:
 the start sequence starts at a first start time and ends at a first end time, the start sequence having a steady voltage from the first start time to the first end time; and   the predetermined start sequence starts at a second start time and ends at a second end time, the predetermined start sequence having a non-steady voltage from the second start time to the second end time.   
     
     
         14 . The method of  claim 13 , wherein a voltage value of the predetermined start sequence at the second start time is equal to a voltage value of the predetermined start sequence at the second end time. 
     
     
         15 . The method of  claim 11 , wherein:
 the data received from the pressure sensor assembly further includes a bit stream; and   the method further comprises, in response to determining the bit stream having a start sequence similar to a predetermined start sequence, determining, by the controller, the calibration value is not faulty and operating, by the controller, the fixed displacement pump based on at least the detected pressure and the calibration value.   
     
     
         16 . The method of  claim 11 , wherein the calibration value comprises a frequency value associated with a fixed pressure. 
     
     
         17 . The method of  claim 11 , wherein the calibration value comprises a pressure differential value associated with a fixed frequency. 
     
     
         18 . The method of  claim 11 , wherein the calibration value is an offset at zero pump pressure when the fixed displacement pump is inactive. 
     
     
         19 . The method of  claim 18 , wherein the calibration value is the offset at the zero pump pressure when power is first applied to the reductant dosing system. 
     
     
         20 . The method of  claim 19 , further comprising compensating, by the controller, for the offset at the zero pump pressure while operating the fixed displacement pump.