EMISSIONS CONTROL IN DIESEL ENGINES

An exhaust system is configured with a diesel oxidation catalyst that receives first exhaust gases from a diesel engine, a diesel particulate filter that receives second exhaust gases from the diesel oxidation catalyst. A first sensor in the exhaust system determines first exhaust gases data and transmits the first exhaust gases data to a controller while a second sensor determines second exhaust gases data and transmits the second exhaust gases data to the controller. The controller estimates unmeasured exhaust gases data based on the first exhaust gases data and the second exhaust gases data and determines when to initiate a regeneration cycle for the diesel particulate filter.

TECHNICAL FIELD

The present disclosure relates to emissions controls for internal combustion engines generally and in particular to methods and systems for emissions control in diesel engines.

BACKGROUND

Diesel engines are used in a variety of stationary and mobile applications. Diesel engines are commonly used in cars and trucks, for example. In order to comply with emissions standards, many diesel engines utilize catalysts, such as diesel oxidation catalysts (DOC). DOCs may reduce emissions of diesel engines by oxidizing hydrocarbons and carbon monoxide into carbon dioxide and water. Diesel engines may also, or instead, use one or more diesel particulate filters (DPFs) to reduce emissions by removing diesel particulate matter from the exhaust gases of the engine. Accumulated particulate matter in a DPF can be removed by a process called regeneration. Many DPFs can be actively regenerated by burning off the accumulated particulate through the use of a catalyst and/or by burning fuel in the exhaust system to heat the DPF to particulate combustion temperatures. A diesel engine may also passively regenerate a DPF by running the engine to elevate exhaust temperatures and/or produce emissions of the nitrogen oxides NO and NO2(collectively NOx) to oxidize the accumulated particulate matter. Regenerating too often can shorten the lifespan of a DPF and other components of an exhaust system and waste fuel, while not regenerating often enough can cause inefficient fuel usage in the engine.

BRIEF DESCRIPTION OF THE INVENTION

In an exemplary non-limiting embodiment, a diesel engine exhaust system may be configured with a diesel oxidation catalyst that receives first exhaust gases from a diesel engine and a diesel particulate filter that receives second exhaust gases from the diesel oxidation catalyst. A first sensor may determine first exhaust gases data and transmit such data to a controller while a second sensor may determine second exhaust gases data and transmit such data to the controller. The controller may estimate unmeasured exhaust gases data based on the first exhaust gases data and the second exhaust gases data and determine when to initiate a regeneration cycle for the diesel particulate filter.

In another exemplary non-limiting embodiment, a method is disclosed for receiving first exhaust gases from a diesel engine at a diesel oxidation catalyst and receiving second exhaust gases from the diesel oxidation catalyst at a diesel particulate filter. First exhaust gases data may be determined at a first sensor and transmitted to a controller while second exhaust gases data may be determined at a second sensor and transmitted to the controller. The controller may estimate unmeasured exhaust gases data based on the first exhaust gases data and the second exhaust gases data and determine, based on the unmeasured exhaust gases data, when to initiate a regeneration cycle for the diesel particulate filter.

In another exemplary non-limiting embodiment, an engine may include a diesel internal combustion component that generates first exhaust gases. A diesel oxidation catalyst may receive the first exhaust gases from the diesel internal combustion component and a diesel particulate filter may receive second exhaust gases from the diesel oxidation catalyst. A first sensor may determine first exhaust gases data and transmit such data to a controller while a second sensor may determine second exhaust gases data and transmits such data to the controller. The controller may estimate unmeasured exhaust gases data based on the first exhaust gases data and the second exhaust gases data and determines when to initiate a regeneration cycle for the diesel particulate filter.

The foregoing summary, as well as the following detailed description, is better understood when read in conjunction with the drawings. For the purpose of illustrating the claimed subject matter, there is shown in the drawings examples that illustrate various embodiments; however, the invention is not limited to the specific systems and methods disclosed.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates exemplary system100, including diesel engine110and exhaust system111, that may be implemented according to an embodiment. Note that the entire system100may also be referred to as an “engine”. System100as illustrated is a simplified block diagram that will be used to explain the concepts disclosed herein, and therefore is not to be construed as setting forth any physical requirements or particular configuration required for any embodiment disclosed herein. All components, devices, systems, and methods described herein may be implemented with number of components of any shape, form, or type, and any combination of any such components that are capable of implementing the disclosed embodiments are contemplated as within the scope of the present disclosure.

Diesel engine110may be any type of internal combustion engine that operates on diesel fuel or any device, component, or system that includes an internal combustion component that operates on diesel fuel and that generates exhaust gases. Exhaust system111may include DOC120and DPF130. Diesel engine110may exhaust gases through exhaust system111in the direction indicated by exhaust flow101, i.e., from diesel engine110into DOC120and from DOC120into DPF130until gases are ultimately exhausted from DPF130. Each of DOC120and DPF130may convert received exhaust gases to converted exhaust gases as described herein.

Engine control unit115may control diesel engine110and any components of diesel engine110. Engine control unit115may also control fuel injection component150(discussed in more detail herein) and/or an actuator of fuel injection component150in order to control the injection of fuel into exhaust system111for regeneration of DPF130. Engine control unit115may also receive data from fuel injection component150, which may include sensors or any other components that allow it to detect and report data, such as fuel flow rate, exhaust flow rate, exhaust gas species concentrations, temperature, and pressure data. In some embodiments, fuel injection component150may obtain or determine such data by communicating, or otherwise operating in conjunction, with thermocouples, delta pressure sensors, and/or other types of sensors configured in exhaust system111. Alternatively, engine control unit115may obtain or determine exhaust flow rate, exhaust gas species concentrations, temperature, and pressure data for exhaust system111or exhaust gases directed thereto by operating directly with thermocouples, delta pressure sensors, and/or other types of sensors configured in exhaust system111, or by using any other means that may provide or determine such data. Engine control unit115may determine, acquire, or otherwise obtain and may transmit or otherwise provide data such as flow rate, exhaust gas species concentrations, temperature, and pressure data for exhaust system111or exhaust gases directed thereto to controller180or components thereof (discussed in more detail below). All such embodiments are contemplated as within the scope of the present disclosure.

In an embodiment, diesel engine110exhausts gases into DOC120. In this embodiment, DOC120may be diesel oxidation catalyst subsystem. DOC120may contain materials such as palladium and platinum and may oxidize hydrocarbons and carbon monoxide into carbon dioxide and water. Gases exhausted into DOC120by diesel engine110may include particulate matter that may be exhausted from DOC120into DPF130.

DPF130may be any type of diesel particulate filter capable of being regenerated, or any combination of thereof, that may remove particles from exhausted gases exhausted from DOC120, including a cordierite wall flow filter, a silicon carbide wall flow filter, a ceramic fiber filter, and a metal fiber flow through filter. DPF130may remove any portion or all of the particulate matter exhausted from DOC120.

Byproducts of diesel fuel combustion include particulate matter, such as ash, build up in DPF130, increasing the pressure before the filter. In order to return a DPF130to original or improved operating capabilities, a regeneration process or regeneration cycle may be used. Regeneration may be passive or active. In an active regeneration embodiment, fuel injection component150may inject diesel into exhaust system111that may be ignited to introduce high heat into exhaust system111that then burns the particulate matter to burn off the particulate matter captured in DPF130. In some such embodiments, an additional fuel borne catalyst may be introduced with the diesel fuel injected by fuel injection component150to reduce the temperate needed to burn off the particulate matter. Fuel injection component150may be any means, component, device, or combination thereof capable of introducing fuel into the exhaust stream, and all such embodiments are contemplated as within the scope of the present disclosure. In some embodiments, a secondary post injection of fuel may be used for active regeneration, where additional fuel is injected into one or more of the cylinders of diesel engine110in order to increase the temperature of the exhaust gases emitted by diesel engine110. Engine control unit115may issue an instruction that causes this to be performed at diesel engine110, in some embodiment in response to input or an instruction received from controller180.

Note that other methods of active regeneration may also be used with some embodiments, such as using a fuel burner after a turbo configured at diesel engine110to increase the exhaust temperature, using a catalytic oxidizer to increase the temperature of the exhaust emitted by diesel engine110in combination with an after injection (e.g., HC-Doser), using resistive heating coils to increase the temperature of the exhaust emitted by diesel engine110, and/or using microwave energy to increase the particulate temperature of particulate matter in DPF130. Any of these methods may be used in isolation or in combination with any other regeneration methods, passive or active, and all such embodiments are contemplated as within the scope of the present disclosure.

In a passive regeneration embodiment, the heat generated by diesel engine110's exhaust may be used to burn off the particulate matter in DPF130. In such embodiments, a catalyst may be introduced into exhaust system111to facilitate the burning of the particulate matter, which happens when the NOx in DPF130reacts with the soot captured in DPF130. Controller180may determine or otherwise estimate the amount of NOx in DPF130and determine or estimate whether enough NOx is in or entering DPF130to adequately passively regenerate DPF130and, if so, controller180may not request active regeneration thereby saving fuel and improving fuel economy. If controller180estimates that there is not enough NOx going into DPF130, then controller180may request or transmit instructions for active regeneration. Note that both passive and active regeneration may be used in some embodiments.

Exhaust system111may be configured with controller180having at least two components, estimator160and control algorithm170. Note that estimator160and control algorithm170may be combined, for example, as portions of a single software module or component, or may be separately implemented in separate software and/or hardware components. Controller180may be any type and any number of computing devices, software modules, or any combination thereof, and may be implemented by a device dedicated to performing the functions of a controller as described herein or by a device that performs other additional functions. All such embodiments are contemplated as within the scope of the present disclosure.

NOx sensor161may be configured to detect and/or determine measurements of NOx from exhaust gases entering DOC120. NOx sensor161may be configured to provide or otherwise transmit this data, directly or indirectly, to controller180and/or estimator160. NOx sensor162may be configured to detect and/or determine measurements of NOx from exhaust gases exiting DPF130. NOx sensor162may be configured to provide or otherwise transmit this data, directly or indirectly, to controller180and/or estimator160.

Estimator160may receive, using any means, including wireless communications, wired communications, or any combination thereof, measurements of particular gases, species concentrations, or other measurements from various sensors that may be configured at various points in exhaust system111, including NOx sensors161and162. Estimator160may also receive other data, such as flow rate, temperature, species concentrations, and pressure data for exhaust system111or exhaust gases directed thereto, from other components of system100, such as engine control unit115. Estimator160may exercise models of exhaust systems to determine estimates of exhaust system states and gas contents that are not directly measured. For example, estimator160may exercise a model of a DOC and a DPF configured similar to the particular configuration of DOC120and DPF130to determine estimates NOx concentrations at points in exhaust system111where direct measurements are not made, such as at the point between DOC120and DPF130. In another example, estimator160may estimate other key species (e.g., CO, NH3and CH4) concentrations at various points in exhaust system111(e.g., before gasses enter DOC120) based on data received from engine control unit115using maps and/or correlations. Estimator160may also, or instead, use this information to estimate particulate matter levels in DPF130. The models used by estimator160may be linear or non-linear models (e.g., extended Kalman filters) that may be derived from math-based DOC and/or DPF models. All such models and any others that may be used to estimate NOx concentrations and/or particulate matter deposits are contemplated as within the scope of the present disclosure.

Estimator160may obtain other operating condition data, such as flow rate, temperature, and pressure data, from engine control unit115, indirectly or directly from fuel injection component150, and/or indirectly or directly from other components of diesel engine110and/or exhaust system111, such as thermocouples and delta pressure sensors. Estimator160may take the measurements received from NOx sensors161and162in combination with any other operating condition data and estimate, by exercising models representing similar exhaust systems, the quantity and/or concentration of NO and NO2in the gases entering DPF130. Estimator160may also, or instead, estimate the storage of any gases, particulate matter, and/or substances within any catalyst and/or filter, and/or estimate the quantities and/or concentrations of any other gases or any other substances that may be present anywhere in exhaust system111, regardless of whether such gases or substances are directly measured by sensors or using any other means. All such embodiments are contemplated as within the scope of the present disclosure.

Estimator160may provide such estimates to control algorithm170that may then determine a time of initiation of an active regeneration cycle for DPF130and, in some embodiments, a duration of active regeneration. For example, control algorithm170may determine when to activate fuel injection component150, for how long fuel injection component150should be activated, and/or the particular fuel/catalyst mix that should be used by fuel injection component150. In some embodiments, control algorithm170that may determine a time of initiation of injection of a catalyst to assist in passive regeneration of DPF130and, in some embodiments, a duration of such catalyst injection. Instructions for performing injections of fuel and/or catalyst may then be transmitted or otherwise provided to engine control unit115for application to fuel injection component150. Alternatively, control algorithm170and/or controller180may directly control fuel injection component150.

FIG. 2illustrates exemplary, non-limiting method200of implementing an embodiment as disclosed herein. Method200, and the individual actions and functions described in method200, may be performed by any one or more devices or components, including those described herein, such as controller180ofFIG. 1, and/or any other component or device of the systems illustrated inFIG. 1. In an embodiment, method200may be performed by any other devices, components, or combinations thereof, in some embodiments in conjunction with other systems, devices and/or components. Note that any of the functions and/or actions described in regard to any of the blocks of method200may be performed in any order, in isolation, with a subset of other functions and/or actions described in regard to any of the other blocks of method200or any other method described herein, and in combination with other functions and/or actions, including those described herein and those not set forth herein. All such embodiments are contemplated as within the scope of the present disclosure.

At block210, data may be received from sensors configured in an exhaust system and/or from any other component of an engine or exhaust system. For example, at block210, in an exhaust system having a DOC configured upstream from a DPF, a NOx sensor located upstream from the DOC (e.g., NOx sensor161) may transmit sensor data such as NOx quantity and/or concentration. In such a system, a NOx sensor may be located downstream from the DPF and may transmit sensor data such as NOx quantity and/or concentration of the exhaust traveling past the sensor at that location in the catalyst system. Other data may also be received from other components. For example, flow rate, temperature, species concentration, and pressure data for a catalyst system or exhaust gases directed thereto may be received from an engine control unit (e.g., engine control unit115). Such data may be received at a controller or computing device such as any of those described herein.

At block220, estimates may be made for unmeasured data. For example, estimates of data associated with gases such as NO and NO2at points in a catalyst system where direct measurements are not made, such as at a point between a DOC and a DPF or where exhaust gases initially enter an exhaust system. Such data may include estimates of other key species (e.g., CO, NH3, and CH4) concentrations at various points in an exhaust system111made based on data received from an engine control unit by using maps and/or correlations.

At block230, a control algorithm may be exercised to determine regeneration cycle initiation times and duration for a DPF in order to improve or maintain proper operating conditions for a diesel engine and/or exhaust system. The control algorithm may also, or instead, determine a fuel/catalyst mix for fuel to be used in active regeneration, or an initiation time and duration for addition of a catalyst into an exhaust system to assist with passive regeneration.

At block240, regeneration time, duration, and fuel/catalyst mix, or instructions to perform regeneration or otherwise introduce fuel and/or catalyst to an exhaust system may be transmitted to the appropriate component. For example, where components are configured to receive settings directly, a controller that determines a regeneration time, duration, and fuel/catalyst mix may transmit these parameters to the component. Alternatively, for components that are configured to receive instructions, a controller may be configured to transmit instructions to implement regeneration using these parameters to the component.

For example, a controller may determine that a time for active regeneration has arrived and may instruct a fuel injection component configured in an exhaust system to begin injecting fuel into the exhaust system. Similarly, a controller may determine a current fuel/catalyst mix for a fuel injection component and may transmit this setting to the fuel injection component or transmit a command that will cause the fuel injection component to operate using the determined fuel/catalyst mix. Note that in some embodiments, a determination may be made that no regeneration is currently needed, and therefore no instruction or setting may be transmitted.

The technical effect of the systems and methods set forth herein is the ability to meet emissions regulations and achieve precise control of diesel engine emissions using estimation and control algorithms with a minimum number of sensors, thereby reducing the cost and complexity of a diesel engine exhaust system. As will be appreciated by those skilled in the art, the use of the disclosed processes and systems may reduce the emissions of such engines while enabling them to run longer and be more reliable, cleaner, and less expensive. Those skilled in the art will recognize that the disclosed diesel engine exhaust systems and methods may be combined with other systems and technologies in order to achieve even greater emissions control and engine performance. All such embodiments are contemplated as within the scope of the present disclosure.

FIG. 3and the following discussion are intended to provide a brief general description of a suitable computing environment in which the diesel engine exhaust systems and methods disclosed herein and/or portions thereof may be implemented. For example, the functions of controller180may be performed by one or more devices that include some or all of the aspects described in regard toFIG. 3. Some or all of the devices described inFIG. 3that may be used to perform functions of the claimed embodiments may be configured in a controller that may be embedded into a system such as those described with regard toFIG. 1. Alternatively, some or all of the devices described inFIG. 3may be included in any device, combination of devices, or any system that performs any aspect of a disclosed embodiment.

Although not required, the diesel engine exhaust systems and methods disclosed herein may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer, such as a client workstation, server or personal computer. Such computer-executable instructions may be stored on any type of computer-readable storage device that is not a transient signal per se. Generally, program modules include routines, programs, objects, components, data structures and the like that perform particular tasks or implement particular abstract data types. Moreover, it should be appreciated that the diesel engine exhaust systems and methods disclosed herein and/or portions thereof may be practiced with other computer system configurations, including hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers and the like. The methods and systems disclosed herein may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

FIG. 3is a block diagram representing a general purpose computer system in which aspects of the methods and systems disclosed herein and/or portions thereof may be incorporated. As shown, the exemplary general purpose computing system includes computer320or the like, including processing unit321, system memory322, and system bus323that couples various system components including the system memory to processing unit321. System bus323may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The system memory may include read-only memory (ROM)324and random access memory (RAM)325. Basic input/output system326(BIOS), which may contain the basic routines that help to transfer information between elements within computer320, such as during start-up, may be stored in ROM324.

Computer320may further include hard disk drive327for reading from and writing to a hard disk (not shown), magnetic disk drive328for reading from or writing to removable magnetic disk329, and/or optical disk drive330for reading from or writing to removable optical disk331such as a CD-ROM or other optical media. Hard disk drive327, magnetic disk drive328, and optical disk drive330may be connected to system bus323by hard disk drive interface332, magnetic disk drive interface333, and optical drive interface334, respectively. The drives and their associated computer-readable media provide non-volatile storage of computer-readable instructions, data structures, program modules and other data for computer320.

Although the exemplary environment described herein employs a hard disk, removable magnetic disk329, and removable optical disk331, it should be appreciated that other types of computer-readable media that can store data that is accessible by a computer may also be used in the exemplary operating environment. Such other types of media include, but are not limited to, a magnetic cassette, a flash memory card, a digital video or versatile disk, a Bernoulli cartridge, a random access memory (RAM), a read-only memory (ROM), and the like.

A number of program modules may be stored on hard disk drive327, magnetic disk329, optical disk331, ROM324, and/or RAM325, including an operating system335, one or more application programs336, other program modules337and program data338. A user may enter commands and information into the computer320through input devices such as a keyboard340and pointing device342. Other input devices (not shown) may include a microphone, joystick, game pad, satellite disk, scanner, or the like. These and other input devices are often connected to the processing unit321through a serial port interface346that is coupled to the system bus, but may be connected by other interfaces, such as a parallel port, game port, or universal serial bus (USB). A monitor347or other type of display device may also be connected to the system bus323via an interface, such as a video adapter348. In addition to the monitor347, a computer may include other peripheral output devices (not shown), such as speakers and printers. The exemplary system ofFIG. 3may also include host adapter355, Small Computer System Interface (SCSI) bus356, and external storage device362that may be connected to the SCSI bus356.

The computer320may operate in a networked environment using logical and/or physical connections to one or more remote computers or devices, such as remote computer349, components of diesel engine110, and fuel injection component150. Components of diesel engine110and fuel injection component150may be any device as described herein capable of performing the described functions. Remote computer349may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and may include many or all of the elements described above relative to the computer320, although only a memory storage device350has been illustrated inFIG. 3. The logical connections depicted inFIG. 3may include local area network (LAN)351and wide area network (WAN)352. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets, and the Internet.

When used in a LAN networking environment, computer320may be connected to LAN351through network interface or adapter353. When used in a WAN networking environment, computer320may include modem354or other means for establishing communications over wide area network352, such as the Internet. Modem354, which may be internal or external, may be connected to system bus323via serial port interface346. In a networked environment, program modules depicted relative to computer320, or portions thereof, may be stored in a remote memory storage device. It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between computers may be used.

Computer320may include a variety of computer-readable storage media. Computer-readable storage media can be any available tangible, non-transitory, or non-propagating media that can be accessed by computer320and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer-readable media may comprise computer storage media and communication media. Computer storage media include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other tangible medium which can be used to store the desired information and which can be accessed by computer320. Combinations of any of the above should also be included within the scope of computer-readable media that may be used to store source code for implementing the methods and systems described herein. Any combination of the features or elements disclosed herein may be used in one or more embodiments.