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US 8,920,757 B1Granted
Reductant dosing control systems and methods
AssigneeCummins Emission Solutions Inc.
InventorsSrivardhan Chandrapati, Yongquan Chai, Stephen M. Holl, Shu Zhang
Life of this patent
Estimating the term…
Abstract
Reductant dosing systems and methods for engine exhaust aftertreatment are disclosed. The opening and closing of a metering valve in the reductant dosing system is controlled in a manner that mitigates pressure oscillations in the dosing system. The metering valve is opened in response to the dosing command exceeding a minimum threshold value and the differential pressure across the metering valve exceeding a differential pressure threshold. The metering valve is closed in response to either the differential pressure across the metering valve dropping below a differential pressure threshold or the actual dosed quantity exceeding the dosing command.
Claims23
A method, comprising:
- determining a dosing command that includes a quantity of a reductant to inject with a dosing system for treatment of an exhaust gas in an exhaust system that includes a selective catalytic reduction catalyst;
- and
- injecting the reductant into the exhaust system through a metering valve of the dosing system over a variable frequency dosing cycle while measuring a quantity of injected reductant, wherein the variable frequency dosing cycle includes:
- closing the metering valve from an open condition when either a differential pressure across the metering valve is less than a first differential pressure threshold or the measured quantity of injected reductant is greater than the quantity of reductant to inject from the dosing command;
- and
- opening the metering valve from a closed condition when the quantity of reductant to inject from the dosing command is more than a threshold amount and, when the metering valve is in the closed condition in response to the differential pressure being less than the first differential pressure threshold, the differential pressure being more than a second differential pressure threshold, wherein the second differential pressure threshold is greater than the first differential pressure threshold.
3 more elements
A method, comprising:
- injecting a quantity of a reductant with a dosing system over a variable frequency dosing cycle in response to a dosing command to treat an exhaust gas in an exhaust system that includes a selective catalytic reduction catalyst, wherein the variable frequency dosing cycle includes sequentially opening and closing a metering valve during a dosing cycle to selectively pass reductant through the metering valve to the exhaust system, wherein the metering valve is opened from a closed condition when the dosing command is more than a threshold amount of reductant and the differential pressure across the metering valve is more than a differential pressure threshold, and closing the metering valve from an open condition when the differential pressure across the metering valve is either less than the differential pressure threshold or an injected quantity of the reductant is greater than the dosing command.
A system, comprising:
- a doser fluidly connected to a source of reductant, wherein the doser is connected to an exhaust system with a metering valve between the doser and the exhaust system, and the doser includes a pump operable to pressurize the reductant through the metering valve in response to a dosing command;
- a pressure sensor associated with the metering valve operable to indicate a differential pressure across the metering valve;
- and
- a controller connected to the metering valve that is configured to selectively open and close the metering valve over a variable frequency dosing cycle in response to a measured quantity of reductant through the metering valve and the differential pressure, wherein the controller is further configured to:
- close the metering valve from an open condition when either the differential pressure across the metering valve is either less than a first differential pressure threshold or the measured quantity of the reductant is greater than the dosing command;
- and
- open the metering valve from a closed condition when the dosing command is more than a threshold amount and, if the metering valve is in the closed condition in response to the differential pressure being less than the first differential pressure threshold, when the differential pressure is more than a second differential pressure threshold, wherein the second differential pressure threshold is greater than the first differential pressure threshold.
4 more elements
Dependencies are inferred from the claim text.