Urea injection systems wash cycles
First Claim
1. A system for urea dosing of an exhaust aftertreatment system, the system comprising:
- a blending chamber including a urea inlet, a gas inlet, and an outlet;
a urea valve configured to provide urea solution to the urea inlet;
a gas flow passage extending from the gas inlet;
a gas valve configured to control flow of pressurized gas to the gas flow passage and the gas inlet;
a pressure sensor configured to sense pressure at a location downstream from the gas inlet and the urea inlet; and
a controller in operative communication with the pressure sensor, the urea valve and the gas valve;
wherein the controller is configured to actuate the urea valve and the gas valve to provide a combined flow of urea solution and air at the outlet of the blending chamber, evaluate pressure information from the pressure sensor indicating pressure of the combined flow, close the gas valve based upon a comparison of the pressure information and a pressure threshold, actuate the urea valve to fill at least a portion of the blending chamber with urea solution when the pressure information is below a second threshold, the second threshold corresponding to the gas valve being completely closed, and open the gas valve to expel urea solution from the blending chamber.
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Accused Products
Abstract
Urea injection system wash cycle methods and systems are disclosed. An exemplary wash cycle method includes operating a urea injection system to provide urea solution to a first inlet of a blending chamber, provide pressurized gas to a second inlet of the blending chamber, and output a combined flow of pressurized gas and urea solution from the blending chamber. A pressure of the combined flow at a location downstream from the first inlet and the second inlet is monitored. A wash cycle is performed based upon the monitored pressure wherein the flow of pressurized gas is turned off and urea solution is provided to the blending chamber. An exemplary system includes a controller configured to control a urea injection system to perform a wash cycle in accordance with the exemplary method.
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Citations
26 Claims
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1. A system for urea dosing of an exhaust aftertreatment system, the system comprising:
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a blending chamber including a urea inlet, a gas inlet, and an outlet; a urea valve configured to provide urea solution to the urea inlet; a gas flow passage extending from the gas inlet; a gas valve configured to control flow of pressurized gas to the gas flow passage and the gas inlet; a pressure sensor configured to sense pressure at a location downstream from the gas inlet and the urea inlet; and a controller in operative communication with the pressure sensor, the urea valve and the gas valve; wherein the controller is configured to actuate the urea valve and the gas valve to provide a combined flow of urea solution and air at the outlet of the blending chamber, evaluate pressure information from the pressure sensor indicating pressure of the combined flow, close the gas valve based upon a comparison of the pressure information and a pressure threshold, actuate the urea valve to fill at least a portion of the blending chamber with urea solution when the pressure information is below a second threshold, the second threshold corresponding to the gas valve being completely closed, and open the gas valve to expel urea solution from the blending chamber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method comprising:
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providing a system configured to selectably provide urea solution to a first inlet of a blending chamber and selectably provide pressurized gas to a second inlet of the blending chamber via a check valve; operating the system to provide urea solution to the first inlet, provide gas to the second inlet, and output a combined flow of pressurized gas and urea solution from the blending chamber; monitoring pressure of the combined flow at a location downstream from the first inlet and the second inlet; turning off the gas flow when the monitored pressure is below a first value; providing urea solution to the first inlet with the gas flow off when the monitored pressure is below a second value effective to fill at least a portion of the blending chamber with urea solution, the second value selected to ensure that the check valve is closed; and turning on the gas flow to expel urea solution from the blending chamber. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method comprising:
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providing an SCR urea injection system configured to provide urea solution to a first inlet of a blending chamber and provide pressurized gas to a second inlet of the blending chamber; operating the system to provide urea solution to the first inlet, provide pressurized gas to the second inlet, and provide a combined flow of pressurized gas and urea solution from the blending chamber to an SCR catalyst; initiating a wash cycle based upon pressure of the combined flow meeting a predetermined pressure criterion and a timer meeting a predetermined time criterion, the wash cycle including providing urea solution to the first inlet with the gas flow off, the urea provided to the first inlet if the pressure of the combined flow is below a second threshold, the second threshold corresponding to an air shut off valve being completely closed to stop the gas flow, and turning on the gas flow to expel urea solution from the blending chamber; and resuming the operating the system to provide urea solution to the first inlet, provide pressurized gas to the second inlet, and provide the combined flow of pressurized gas and urea solution from the blending chamber to the SCR catalyst. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification