Patent Application
20210123391
The technical field relates to a control apparatus for operating an internal combustion engine, and more particularly, to control a selective catalyst reduction (SCR) or selective catalyst reduction on filter (SCRF) exhaust gas after-treatment system.
An internal combustion engine for a motor vehicle generally includes an engine block defining at least one cylinder accommodating a reciprocating piston coupled to rotate a crankshaft. The cylinder is closed by a cylinder head that cooperates with the reciprocating piston to define a combustion chamber. A fuel and air mixture is cyclically disposed in the combustion chamber and ignited, thereby generating hot expanding exhaust gasses that cause the reciprocating movements of the piston. The fuel is typically injected into each cylinder by a respective fuel injector. The fuel is provided at high pressure to each fuel injector from a fuel rail in fluid communication with a high pressure fuel pump that increases the pressure of the fuel received from a fuel source. Operation of the internal combustion engine is generally controlled by one or more electronic control units (ECUs) operably coupled to the internal combustion engine and an array of sensors and actuators, such as the fuel injector.
Due to stringent emissions regulation, internal combustion engines generally include exhaust gas after-treatment systems. An after-treatment system may include one or more after-treatment devices provided in an exhaust system of the internal combustion engine. For example, an after-treatment system may include an oxidation catalyst such as a diesel oxidation catalyst (DOC), which utilizes a chemical process in order to break down constituents from diesel engines in the exhaust stream, turning them into generally harmless compositions. DOCs typically have a honeycomb shaped configuration coated in a catalyst designed to trigger a chemical reaction to reduce these constituents. DOCs may contain palladium (Pd) and platinum (Pt) or cerium oxide, which serve as catalysts to oxidize hydrocarbons and carbon monoxide into carbon dioxide and water. An alternative to DOCs may be a three-way catalyst (TWC).
In a further alternative, a lean NOx trap (LNT) may be used. A LNT is a device that traps nitrogen oxides (NOx) contained in the exhaust gas and is generally located in the exhaust system upstream of a diesel particulate filter (DPF). More specifically, a LNT is a catalytic device containing catalysts, such as rhodium (Rh), Pt and Pd, and adsorbents, such as barium based elements, which provide active sites suitable for binding the nitrogen oxides (NOx) contained in the exhaust gas in order to trap them within the device itself.
After-treatment systems may also include a diesel particular filter (DPF) which filters the particulate matter (PM) and a selective catalytic reduction (SCR) device which is a catalytic device for reducing the nitrogen oxides (NOx) contained in the exhaust gas into diatomic nitrogen (N2) and water (H2O), with the aid of a gaseous reducing agent, typically ammonia (NH3) that can be obtained by urea (CH4N2O) thermo-hydrolysis and that is absorbed inside the catalyst. Typically, urea is injected from a dedicated tank into the exhaust line where it mixes with the exhaust gas upstream the SCR. Other fluids can be used in a SCR in lieu of urea and are generally referred to as diesel exhaust fluids (DEF). An alternative to the SCR is a SCRF (SCR on Filter), namely a device that combines in a single unit an SCR device and a DPF.
Control of the after-treatment system, and in particular the control of the introduction of DEF to provide effective operation of the SCR/SCRF, requires development of a computationally intensive model of the SCR/SCRF. Furthermore, owing to the complexity of the SCR/SCRF models, existing after-treatment systems are provided only open loop control strategies augmented with complex adaptation strategies. Although performance of SCR/SCRF-based after-treatment systems might be significantly improved by them, SCR/SCRF-based after-treatment systems have not proven to be amenable to closed loop or other advanced control strategies.
In accordance with a herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. In this embodiment, the CLO output signal at least includes an NH3 storage estimate into the SCRF catalyst and also verifies the conditions described below. The NH3 storage estimate is enhanced when an NH3 slip evident condition is verified by comparing NOx sensor readings and when a linearized model is not coherent with the NH3 slip evident condition. The NH3 storage estimate is enhanced when urea injection into the SCRF at least once in a time window is verified and when NOx sensor readings are below sensor accuracy. The NH3 storage estimate comprises an adjusted output matrix of discrete-time linearized model and an adjusted NOx sensor measurement, NOxSnsr_new_measure=NOxSnsr_real_measure/cross_sensitivity_factor. The NH3 storage estimate further comprises an adjusted NOx sensor estimation, NOxSnsr_estimation=NH3_only_estimation.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO output further includes an ammonia coverage ratio representing a quantity of ammonia stored within the SCRF device.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO output further includes estimated ammonia NH3 concentration within the exhaust gases.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO further includes a selective catalyst reduction (SCR) model, and the SCR model is configured to provide an estimated ammonia NH3 concentration within the exhaust gases.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO further includes a filter, the filter being configured to provide at least one parameter value to the SCR model.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO further includes a NOx sensor model, and the NOx sensor model is configured to provide the NOx concentration estimate.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO further includes a NOx sensor model, and the NOx sensor model is configured to provide the NOx concentration estimate. The CLO further has a filter configured to provide at least one parameter value to the NOx sensor model.
In accordance with a further herein described embodiment, an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. Each of the CLO and the ECU are operatively coupled to receive an operating parameter of the internal combustion engine. The CLO and the ECU are further arranged to be operable upon the operating parameter to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases.
In accordance with a further herein described embodiment, a vehicle includes an exhaust gas after-treatment system is provided for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is in communication with the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a CLO output to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine. The CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the CLO output to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO output further includes ammonia coverage ratio representing a quantity of ammonia stored within the SCRF device.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO output further includes an estimated ammonia NH3 concentration within the exhaust gases.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO includes a selective catalyst reduction (SCR) model, the SCR model being configured to provide an estimated ammonia NH3 concentration within the exhaust gases.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO includes a filter, the filter that is configured to provide at least one parameter value to the SCR model.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO includes a NOx sensor model. The NOx sensor model is configured to provide the NOx concentration estimate.
In accordance with a further herein described embodiment, a controller is provided for a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output, an oxides of nitrogen (NOx) sensor coupled to the treated exhaust gas output. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and the exhaust gas after-treatment system. The controller includes a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU. The CLO output signal at least includes an exhaust gas NOx concentration estimate. The ECU is arranged to be operable upon the NOx concentration estimate to control the exhaust gas after-treatment system and the internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases. The CLO includes a filter configured to provide at least one parameter value to the NOx sensor model.
In accordance with a further herein described embodiment, a method is provided to control a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device that is in communication with exhaust gases from the internal combustion engine. A treated exhaust gas output from the SCRF device is coupled to an oxides of nitrogen (NOx) sensor. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and to the exhaust gas after-treatment system. The method includes providing via a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal an exhaust gas NOx concentration estimate to the ECU. The exhaust gas after-treatment system and the internal combustion engine is controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate.
In accordance with a further herein described embodiment, a method is provided to control a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device that is in communication with exhaust gases from the internal combustion engine. A treated exhaust gas output from the SCRF device is coupled to an oxides of nitrogen (NOx) sensor. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and to the exhaust gas after-treatment system. The method includes providing via a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal an exhaust gas NOx concentration estimate to the ECU. The exhaust gas after-treatment system and the internal combustion engine are controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate. The CLO further provides an estimated ammonia (NH3) concentration within the exhaust gases, and the exhaust gas after-treatment system and the internal combustion engine are controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate and the estimated NH3 concentration.
In accordance with a further herein described embodiment, a method is provided to control a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device that is in communication with exhaust gases from the internal combustion engine. A treated exhaust gas output from the SCRF device is coupled to an oxides of nitrogen (NOx) sensor. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and to the exhaust gas after-treatment system. The method includes providing via a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal an exhaust gas NOx concentration estimate to the ECU. The exhaust gas after-treatment system and the internal combustion engine is controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate. The CLO further provides an ammonia coverage value and the exhaust gas after-treatment system and the internal combustion engine are controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate and the ammonia coverage value.
In accordance with a further herein described embodiment, a method is provided to control a vehicle internal combustion engine exhaust gas after-treatment system. The exhaust gas treatment system includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device that is in communication with exhaust gases from the internal combustion engine. A treated exhaust gas output from the SCRF device is coupled to an oxides of nitrogen (NOx) sensor. The NOx sensor has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. An electronic control unit (ECU) is operatively coupled to the internal combustion engine and to the exhaust gas after-treatment system. The method includes providing via a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal an exhaust gas NOx concentration estimate to the ECU. The exhaust gas after-treatment system and the internal combustion engine is controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate. Provided to the ECU and the CLO also is at least one internal combustion engine operating parameter. The exhaust gas after-treatment system and the internal combustion engine are controlled to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate and the at least one internal combustion engine operating parameter.
The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.
The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. Exemplary embodiments will now be described with reference to the drawings, wherein conventional or commonly known elements may be omitted for clarity.
Some embodiments may include an automotive system 10, which as shown in
The air may be distributed to the air intake port(s) through the intake manifold. An air intake duct may provide air from the ambient environment to the intake manifold. In other embodiments, a throttle body may be provided to regulate the flow of air into the manifold. In still other embodiments, a forced air system such as a turbocharger, having a compressor rotationally coupled to a turbine, may be provided. Rotation of the compressor increases the pressure and temperature of the air in the duct and manifold, and an intercooler disposed in the duct may reduce the temperature of the air.
Exhaust gases 14 produced by the ICE 12 are communicated to an exhaust system 16, which in accordance with the herein described embodiments includes an exhaust gas after-treatment system 18 including one or more exhaust after-treatment devices (not depicted in
With continued reference to
A control structure 36 is operatively associated with the after-treatment system 16 and, in accordance with the herein described embodiments, includes an electronic control unit (ECU) 38 and a closed loop observer (CLO) 40. The ECU 38 and the CLO 40 are operatively coupled to receive data in the form of electronic signals from one or more sensors and/or devices associated with the ICE 12 represented as ICE sensor and modules data hereinafter referred to as UICE 42. The ECU 28 may receive UICE 42 signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 12. The sensors include, but are not limited to, a mass airflow and temperature sensor, a manifold pressure and temperature sensor, a combustion pressure sensor, coolant and oil temperature and level sensors, a fuel rail pressure sensor, a cam position sensor, a crank position sensor, an exhaust pressure sensor and an exhaust temperature sensor, an EGR temperature sensor, and an accelerator pedal position sensor. Furthermore, the ECU 38 may generate output signals to various control devices that are arranged to control the operation of the ICE 12, including, but not limited to, the fuel injectors, the throttle body and other devices forming part of the after-treatment system 18. The ECU 38 may furthermore receive additional control inputs, such as but not limited to, ambient air temperature, ambient pressure, vehicle speed, gear selected, and the like, hereinafter CIs 44.
In accordance with herein described embodiments, the ECU 38 at least provides a DEF injection signal 46 causing the DEF system (not depicted) to inject a measured quantity of Diesel exhaust fluid or DEF into the exhaust gas flow upstream the SCRF 22. As is known, the DEF is hydrolysized to produce NH3, which is reacted with the exhaust gas flow within the SCRF 22. An exhaust gas output of the SCRF 22 is exhaust gas consisting primarily of N2 and H2O, but also having NOx 32 and NH3 34 components.
The NOx sensor 26 is cross-sensitive to both NOx and NH3, and the data signal Csensor 28 is a function of the NOx 32 and NH3 34 components, namely, the actual concentration of NOx or CNOx and the actual concentration of NH3 or CNH3 of the treated exhaust gas 20 output from the SCRF 22.
Each of the ECU 38 and the CLO 40 may include a digital central processing unit (CPU) having a microprocessor in communication with a memory system, or data carrier, and an interface bus. The microprocessor is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid-state storage, and other non volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the ECU 38 and the CLO 40 to carryout out the steps of such methods and control the ICE 12 and after-treatment system 18. Instead of a CPU, the ECU 38 and/or the CLO 40 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the automotive system 10.
The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 10 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.
An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulation technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a WiFi connection to a laptop.
In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an ASIC, a CD or the like.
In accordance with the herein described embodiments, the CLO 40 has three operative components, although the CLO 40 may have fewer than the depicted three components, the depicted components may be combined into fewer than three components or expanded to include more than three components. The CLO 40 may furthermore incorporate additional components and functionality associated with the operation of the ICE 12 and/or the after-treatment system 18. In the embodiment depicted in
The SCR model 50 may be implemented in accordance with the herein described embodiments as a first order lumped model configured to determine the state:
x=Θθ
where x is the ammonia stored within the SCRF 18 in moles [mol], Θ is the maximum ammonia storage capacity and θ is ammonia coverage ratio. Given the following variables:
a
1
=e
k
-k
/T
a
2
=e
k
-k
/T
a
3
=k
3
a
4
=e
k
-k
/T
a
5
=k
8
x may be given as:
where as described above:
y
1=CNO
y
2=CNH
u
1=CNO
u
2=CNH
F=[m3/s]
T
sampling=[s]
As noted above, the NOx sensor 26 is cross-sensitive to NH3, which means it is not possible to have a pure NOx feedback when there is NH3 present at the outlet of the SCRF 22, which is typical. With reference to
y
m
=y
1+(ks1+ks2F+ks3Tsensor+ks4F2)y2
where (ks1+ks2F+ks3Tsensor+ks4F2) is defined as cross-sensitivity factor, Tsensor is the temperature at the sensor location and the coefficients ks1-ks4 being determined by bench calibration.
The filter 54 may be implemented as an extended Kalman filter taking into consideration configuration of the CLO 40 and the NOx sensor 26 characteristics. The filter 54 takes as inputs (e.g., consumes) the NOx sensor 26 output 28 and in particular the NOx 32 and NH3 34 components of the SCRF 22 output gas, and is used to reconstruct the state (x) i.e., the ammonia coverage ratio stored within the SCRF 22.
The filter 54 utilizes a plurality of parameters in a typical arrangement. A first covariance matrix (Q) is the covariance matrix of the state (x). A second covariance matrix (R) is the covariance matrix of the NOx sensor 26 measurement. In the described exemplary embodiments, each of the matrices Q and R is 1×1 dimensional.
In addition to the typical arrangement, the filter also verifies conditions described below. A first condition or NOx sensors comparison is to identify NH3 slip evident condition by comparison of NOx sensors located at inlet and outlet of the catalyst, taking into account an engineering margin. The NOx sensors comparison is used to identify the NH3 slip evident condition taking into account engineering margin.
A second condition or NH3 condition is that NH3 injection at inlet of the SCR is enabled at least once in a time window in order to avoid the strategy activation when the catalyst is empty. That is, urea injection is enabled at least once in a time window. The second condition is used to avoid to activate the strategy when the catalyst is empty.
A third condition or NOx sensor 2 condition is to verify NOx sensor 2 is reading above sensor accuracy to avoid strategy activations with very low reading. That is, the third condition is used to avoid strategy activations when the sensor readings are below accuracy or very low reading.
A fourth condition or linearized model coherency check condition is that the model is misunderstanding NH3 concentration at outlet of the SCR by a model coherency check, when the coherency check is passed the strategy activation is not needed. The linearized model coherency check is used to avoid strategy activations when the linearized model is correct.
Preferably, if each of the conditions is verified, then the strategy is enabled to obtain an improved NH3 storage estimation. If the strategy is enabled, then the NOx sensor measurement at catalyst outlet can be defined as:
As will be appreciated from the foregoing discussion, to calibrate the CLO 40 it is necessary to identify the kj terms of the SCR model 50, the ksj terms of the NOx sensor model 52 and the Q and R terms of the filter 54. While any suitable methodology may be employed, in an exemplary implementation a one-third/two-thirds bench validation approach is used. For each of a plurality of measurement cycles (e.g., for each of an Artemis cycle, namely a world harmonized light vehicle test cycle (WLTC) and a Federal Test Procedure (FTP) cycle), a dataset is collected from bench testing. In accordance with experimental method and the herein described embodiments, two-thirds of the data is utilized for parameter determination while one-third of the dataset is used for validation for each of the datasets. In this manner, the required terms for the CLO 40 may be established.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment is only an example, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.
