# US 2019/0170035 A1 · Control system for a reductant dosing system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170035 A1 - Document ID: US20190170035A1 - Status: Published application - Kind: A1 - Application number: 15/830,047 - Filed: 2017-12-04 - Published: 2019-06-06 - Earliest claimed: 2017-12-04 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: Shivsinh Hitendrasinh Parmar; Puma Chander Nalla; Johnathan Wingate Trundt; Jun Cai; Brian Vincent Tranel - Web page: https://patentgrep.com/patent/US20190170035A1 ## CPC - F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent} - B01D 53/9418: {for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas} - B01D 53/9431: {Processes characterised by a specific device} - F01N 9/00: Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) - F16K 37/005: {for measuring fluid parameters (F16K37/0033 takes precedence)} - B01D 53/9495: {Controlling the catalytic process} - B01D 2251/2067: Urea - B01D 2259/124: Liquid reactants - F01N 2610/02: the substance being ammonia or urea - F01N 2610/085: Controlling the air supply - F01N 2610/144: Control thereof - F01N 2610/1453: Sprayers or atomisers; Arrangement thereof in the exhaust apparatus - F01N 2610/1473: Overflow or return means for the substances, e.g. conduits or valves for the return path - F01N 2610/148: Arrangement of sensors - F01N 2610/1493: Purging the reducing agent out of the conduits or nozzle - F01N 2900/1808: Pressure - F01N 2900/1824: Properties of the air to be mixed with added substances, e.g. air pressure or air temperature - Y02T 10/12: Improving ICE efficiencies - Y02T 10/40: Engine management systems - F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)} - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A control system is provided to a reductant dosing system for actively maintaining the reductant dosing system ready for use by flushing unused reductant that has crystallized at a return valve of the reductant dosing system. The control system includes a controller that can control a manner of operation of specific system hardware that is present in the reductant dosing system to flush the unused reductant from the return valve that could otherwise cause the return valve to remain a flow-blocking condition as a result of the crystallized reductant. ## Claims ### Claim 1 A control system for a reductant dosing system having a reductant supply circuit and an air supply circuit, the control system comprising: a controller in communication with a pump, a return valve and a first pressure sensor of the reductant supply circuit, and a second pressure sensor and an air supply valve of the air supply circuit, the controller configured to: obtain a value of pressure in an air supply line of the air supply circuit from the second pressure sensor, obtain a value of pressure in a reductant supply line of the reductant supply circuit from the first pressure sensor, compare the pressure in the reductant supply line with the pressure in the air supply line, close the air supply valve and open the return valve, determine whether the pressure in the reductant supply line is greater than a first pre-defined value, operate the pump, open the air supply valve upon lapse of a first pre-determined amount of time from commencement of operation of the pump, discontinue operation of the pump upon lapse of a second pre-determined amount of time from commencement of operation of the pump, the second pre-determined amount of time being greater than the first pre-determined amount of time, and cycle the return valve between its open and closed states while continuing to supply compressed air into the reductant supply line via the opened air supply valve until the pressure in the reductant supply line recedes to a value less than a second pre-defined value, the second pre-defined value being less than the first pre-defined value. ### Claim 2 (depends on 1) The control system of claim 1, wherein the reductant supply circuit of the reductant dosing system further comprises: a first reservoir located upstream of the pump and fluidly coupled to the pump with a first reductant supply line, the first reservoir configured to store a first volume of reductant therein; a reductant dosing injector located downstream of the pump and disposed at fluid communication with the pump; a first check valve disposed in the first reductant supply line and located between the pump and the reductant dosing injector, the first check valve configured to allow a unidirectional flow of reductant from the pump to the reductant dosing injector; and the return valve, the return valve being disposed in a return line that is configured to branch-off from a point on the first reductant supply line located between the first check valve and the reductant dosing injector and fluidly coupled to the first reservoir downstream of the return valve. ### Claim 3 (depends on 2) The control system of claim 2, wherein the first pressure sensor located between the first check valve and the reductant dosing injector, the first pressure sensor configured to output a value indicative of pressure in the first reductant supply line between the first check valve and the reductant dosing injector. ### Claim 4 (depends on 2) The control system of claim 2, wherein the reductant dosing system comprises: a second reservoir disposed in a second reductant supply line fluidly coupled to the return line located between the return valve and the first reservoir; a transfer pump disposed in the second reductant supply line and configured to output pressurized flow of reductant from the second reservoir into the second reductant supply line; and a reductant transfer valve disposed in the second reductant supply line and located between the transfer pump and the return line, wherein each of the transfer pump and the reductant transfer valve is disposed in communication with the controller. ### Claim 5 (depends on 4) The control system of claim 4, wherein the controller is configured to open the reductant transfer valve in response to an amount of reductant in the first reservoir being below a first pre-defined threshold value. ### Claim 6 (depends on 5) The control system of claim 5, wherein each of the return valve, the air supply valve, and the reductant transfer valve is an electromechanically actuated one-way two-position valve. ### Claim 7 (depends on 1) The control system of claim 1, wherein the air supply circuit comprises: a source configured to provide a supply of pressurized air to the reductant dosing injector via the air supply line, wherein the air supply valve is disposed in the air supply line and located downstream of the source, the air supply valve being configured to allow a unidirectional flow of air from the source to the reductant dosing injector. ### Claim 8 (depends on 7) The control system of claim 7, wherein the second pressure sensor is located between the air supply valve and the reductant dosing injector, the second pressure sensor being configured to output a value indicative of an amount of pressure in the air supply line. ### Claim 9 (depends on 1) The control system of claim 1, Wherein in response to the pressure in the first reductant supply line being greater than the first pre-defined value, the controller is configured to: determine whether the return valve is in a closed-state, and if so: open the return valve. ### Claim 10 (depends on 1) The control system of claim 1, wherein in response to opening the return valve, the controller is configured to determine if the pressure in the first reductant supply line continues to be greater than the first pre-defined value. ### Claim 11 A reductant dosing system comprising: a first reservoir configured to store reductant therein; a pump fluidly coupled to the reservoir via a first reductant supply line; a reductant dosing injector disposed in fluid communication with the pump; a first pressure sensor configured to output a value indicative of pressure in the first reductant supply line; and a return valve disposed in a return line and positioned between the pump and the reductant dosing injector and fluidly coupled to the first reservoir downstream of the return valve; a supply of pressurized air connected to the reductant dosing injector via an air supply line; an air supply valve disposed in the air supply line and configured to selectively allow flow of air from the source to the reductant dosing injector; a second pressure sensor located between the air supply valve and the reductant dosing injector, the second pressure sensor configured to output a value indicative of pressure in the air supply line; and a controller communicably coupled to the pump, the first pressure sensor, the second pressure sensor, the return valve, and the air supply valve, the controller configured to: obtain a value of pressure in the air supply line from the second pressure sensor, obtain a value of pressure in the reductant supply line from the first pressure sensor, compare the pressure in the reductant supply line with the pressure in the air supply line, close the air supply valve and open the return valve, determine whether the pressure in the reductant supply line is greater than a first pre-defined value, operate the pump, open the air supply valve upon lapse of a first pre-determined amount of time, discontinue operation of the pump upon lapse of a second pre-determined amount of time, and cycle the return valve between its open and closed states while continuing to supply compressed air into the reductant supply line via the opened air supply valve until the pressure in the reductant supply line recedes to a value less than a second pre-defined value, the second pre-defined value being less than the first pre-defined value. ### Claim 12 (depends on 11) The reductant dosing system of claim 11 further comprising: a second reservoir disposed in a second reductant supply line fluidly coupled to the return line located between the return valve and the first reservoir; a transfer pump disposed in the second reductant supply line and configured to output pressurized flow of reductant from the second reservoir into the second reductant supply line; and a reductant transfer valve disposed in the second reductant supply line and located between the transfer pump and the return line, wherein each of the transfer pump and the reductant transfer valve is disposed in communication with the controller. ### Claim 13 (depends on 12) The reductant dosing system of claim 12, wherein the controller is configured to selectively open the reductant transfer valve in response to an amount of reductant in the first reservoir being below a first pre-defined threshold value. ### Claim 14 (depends on 12) The reductant dosing system of claim 12, wherein each of the return valve, the air supply valve, and the reductant transfer valve is an electromechanically actuated one-way two-position valve. ### Claim 15 (depends on 11) The reductant dosing system of claim 11, wherein in response to the pressure in the first reductant supply line being greater than the first pre-defined value, the controller is configured to: determine whether the return valve is in a closed-state, and if so: open the return valve. ### Claim 16 (depends on 11) The reductant dosing system of claim 11, wherein in response to opening the return valve, the controller is configured to determine if the pressure in the first reductant supply line continues to be greater than the first pre-defined value. ### Claim 17 A method for flushing a return valve associated with a reductant supply circuit of a reductant dosing system, the method comprising: obtaining, using a first pressure sensor, a value of pressure in a reductant supply line of the reductant supply circuit, obtaining, using a second pressure sensor, a value of pressure in an air supply line of the air supply circuit, determining, using a controller communicably coupled to the first and second pressure sensors, whether the air supply line and the reductant supply line are hermetically sealed based on a comparison of the pressure in the reductant supply line with the pressure in the air supply line, confirming, by the controller, that the return valve is blocked by opening the return valve and determining Whether the pressure in the reductant supply line remains greater than a first pre-defined value, and operating, by the controller, a pump disposed in the reductant supply line in response to a confirmation by the controller that the return valve is blocked; opening the air supply valve, by the controller, upon lapse of a first pre-determined amount of time from commencement of operation of the pump, discontinuing operation of the pump, by the controller, upon lapse of a second pre-determined amount of time from commencement of operation of the pump, and cyclically moving the return valve between its open and closed states, by the controller, while continuing to supply compressed air into the reductant supply line until the pressure in the reductant supply line recedes to a value less than a second pre-defined value, the second pre-defined value being less than the first pre-defined value. ### Claim 18 (depends on 17) The method of claim 17 further comprising opening a reductant transfer valve, by the controller, in response to an amount of reductant in a first reservoir of the reductant supply circuit being below a first pre-defined threshold value. ### Claim 19 (depends on 17) The method of claim 17 further comprising in response to the pressure in the first reductant supply line being greater than the first pre-defined value: determining, by the controller, whether the return valve is in a closed-state, and if so: actuating, by the controller, the return valve to move into an open position. ### Claim 20 (depends on 17) The method of claim 17, wherein upon opening the return valve, the controller is configured to determine if the pressure in the first reductant supply line continues to be greater than the first pre-defined value.