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US 10,480,373 B2Granted
Techniques for control of an SCR aftertreatment system in response to an ammonia slip condition
AssigneeCummins Inc.
InventorMichael Haas
Life of this patent
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Abstract
An exhaust aftertreatment system includes a selective catalytic reduction (SCR) catalyst is disposed in an exhaust gas system of an internal combustion engine. A reductant injector is coupled to the exhaust gas stream at a position upstream of the SCR catalyst. A controller is configured to determine an NH3 slip condition and control operation of the exhaust aftertreatment system in response to the NH3 slip condition to improve deNOx efficiency and reduce NH3 slip.
Claims22
A method, comprising:
- operating an internal combustion engine to produce an exhaust gas flow into an exhaust system including a selective catalytic reduction (SCR) catalyst disposed in the exhaust gas flow, the exhaust system including:
- a reductant injector coupled to the exhaust system at a position upstream of the SCR catalyst;
- a first NOx sensor upstream of the SCR catalyst;
- a second NOx sensor downstream of the SCR catalyst;
- determining a target deNOx efficiency for the SCR catalyst;
- injecting a first amount of reductant into the exhaust gas flow in response to the target deNOx efficiency;
- determining a current deNOx efficiency of the SCR catalyst in removing NOx from the exhaust gas flow as a function of a first output from the first NOx sensor and a second output from the second NOx sensor;
- determining the current deNOx efficiency is less than the target deNOx efficiency;
- detecting an NH3 slip condition;
- in response to detecting the NH3 slip condition, determining a temporary target deNOx efficiency for the SCR catalyst;
- and
- injecting a second amount of the reductant in response to the temporary target deNOx efficiency while increasing the temporary target deNOx efficiency toward the target deNOx efficiency until at least one deNOx efficiency adjustment condition is satisfied, wherein the second amount of reductant is less than the first amount of reductant.
9 more elements
A system, comprising:
- an internal combustion engine operable to produce an exhaust gas flow into an exhaust system, the exhaust system including:
- a selective catalytic reduction (SCR) catalyst disposed in the exhaust gas flow;
- a reductant injector operationally coupled to the exhaust gas flow at a position upstream of the SCR catalyst;
- a first NOx sensor upstream of the SCR catalyst;
- a second NOx sensor downstream of the SCR catalyst;
- a controller connected to the first NOx sensor, the second NOx sensor and the internal combustion engine, the controller being configured to determine:
- a target deNOx efficiency in response to one or more operating conditions of the system and a current deNOx efficiency from a first output of the first NOx sensor and a second output of the second NOx sensor;
- a reductant injector command that provides a feedback controlled NH3 amount in response at least in part to a deviation of the current deNOx efficiency from the target deNOx efficiency;
- the controller further being configured, in response to detection of an NH3 slip condition, to determine:
- a temporary target deNOx efficiency;
- and
- a modified reductant injection command to provide a reduced NH3 amount in response to the temporary target deNOx efficiency while increasing the temporary target deNOx efficiency toward the target deNOx efficiency.
9 more elements
An apparatus, comprising:
- a controller connected to a first NOx sensor upstream of a selective catalytic reduction (SCR) catalyst in an exhaust system and a second NOx sensor downstream of the SCR catalyst, wherein the exhaust system receives an exhaust gas flow produced by operation of an internal combustion engine, the controller including:
- a deNOx efficiency target module configured to determine a target deNOx efficiency for injection of an NH3 amount to achieve the target deNOx efficiency;
- a deNOx efficiency feedback module configured to determine a current deNOx efficiency in response to NOx amounts from the first NOx sensor and the second NOx sensor;
- an NH3 slip detection module configured to detect an NH3 slip condition;
- in response to the NH3 slip condition, the controller suspending injection of the NH3amount for achieving the target deNOx efficiency;
- and
- further comprising an NH3 correction module configured to determine a temporary target deNOx efficiency in response to the NH3 slip condition for injection of a reduced NH3 amount and to increase the temporary target deNOx efficiency toward the target deNOx efficiency during injection of the reduced NH3 amount.
4 more elements
Dependencies are inferred from the claim text.