SYSTEMS AND METHODS FOR DIAGNOSING DESCATALYSATOR STATE AND IMPROVING FUEL SYSTEM CONTROL

Abstract

An exhaust system comprises an engine, a three-way catalytic converter containing a first catalyst and a second catalyst, an exhaust tailpipe adjacent to the three-way catalytic converter, a first oxygen sensor located between the engine and the catalyst, a nitrogen oxide (NOx) sensor located in the three-way catalytic converter, and an engine control module (ECM) configured to receive first oxygen sensor data from the first oxygen sensor, second oxygen sensor data from the NOx sensor, and NOx sensor data from the NOx sensor, wherein the ECM is configured to perform catalyst condition diagnostic operations and to adjust one or more properties of the exhaust system based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data.

Description

INTRODUCTION

[0001] The information provided in this section is intended to provide a general context for the disclosure. The work of the presently named inventors, to the extent described in this section, as well as those aspects of the description that do not otherwise qualify as prior art at the time of filing, are neither expressly nor implicitly acknowledged as prior art to the present disclosure.

[0002] The present disclosure generally relates to systems and methods for diagnosing catalyst condition and improving fuel system control. More specifically, the present disclosure relates to the use of a nitrogen oxide (NOx) sensor to collect data that can be used to improve catalyst condition diagnosis and improve fuel system control. Various sensors have been used to collect data related to various aspects of vehicles. However, data collection often requires fuel cut-off (DFCO) to occur for catalyst condition diagnosis, which interferes with vehicle operation. Accordingly, there is a desire to improve passive data collection for catalyst condition diagnosis while improving fuel system control based on a tailpipe NOx sensor signal. SUMMARY

[0003] One aspect of the disclosure provides an exhaust system for a vehicle comprising an engine, a three-way catalyst including a first catalyst and a second catalyst, an exhaust tailpipe adjacent to the three-way catalyst, a first oxygen sensor disposed between the engine and the catalyst, a second oxygen sensor disposed in the three-way catalyst, a nitrogen oxide (NOx) sensor disposed in the exhaust tailpipe, and an engine control module (ECM) configured to receive first oxygen sensor data from the first oxygen sensor, second oxygen sensor data from the second oxygen sensor, and NOx sensor data from the NOx sensor, wherein the ECM is configured to perform catalyst condition diagnostic operations and fuel control adjustment operations.to adjust one or more characteristics of the exhaust system based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data.

[0004] Implementations of the disclosure may include one or more of the following optional features. According to some implementations, the NOx sensor is located at or near the end of the tailpipe or after the second catalyst, and wherein the NOx sensor monitors tailpipe emissions and provides feedback for the control function based on the first oxygen sensor and the second oxygen sensor, and adjusts fuel control based on the NOx sensor data.

[0005] The ECM may be configured to obtain ammonia (NH3) data from the NOx sensor and hydrocarbon (HC) data, carbon monoxide (CO) data, and particulate matter (PM) data based on the relationship between NOx, HC, CO, and PM from empirical data.

[0006] The ECM may be configured to perform the catalyst condition diagnostic operations during all engine operating conditions that combine or replace the use of a deceleration cut event to perform the catalyst condition diagnostic operations with the first oxygen sensor and the second oxygen sensor.

[0007] The ECM may be configured to iteratively perform catalyst condition diagnostic operations and fuel control adjustment based on NOx sensor data.

[0008] The fuel control adjustment operations may include engine air imbalance corrections and / or engine fuel imbalance corrections based on the NOx sensor data.

[0009] Another aspect of the disclosure provides an exhaust system comprising an engine, a three-way catalyst including a first catalyst and a second catalyst, an exhaust tailpipe adjacent to the three-way catalyst, a first oxygen sensor disposed between the engine and the catalyst, a nitrogen oxide (NOx) sensor disposed within the three-way catalyst, and an engine control module (ECM) configured to receive first oxygen sensor data from the first oxygen sensor, second oxygen sensor data from the NOx sensor, and NOx sensor data from the NOx sensor, wherein the ECM is configured to perform catalyst condition diagnostic operations and adjust one or more characteristics of the exhaust system based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data.

[0010] Implementations of the disclosure may include one or more of the following optional features. According to some implementations, the NOx sensor is disposed between the first catalyst and the second catalyst.

[0011] The ECM may be configured to obtain ammonia (NH3) data from the NOx sensor and hydrocarbon (HC) data, carbon monoxide (CO) data, and particulate matter (PM) data based on the relationship between NOx, HC, CO, and PM from empirical data.

[0012] The ECM may be configured to perform the catalyst condition diagnostic operations and iteratively adjust one or more exhaust system characteristics based on the NOx sensor data.

[0013] Adjusting the one or more exhaust system characteristics may include engine air imbalance corrections and / or engine fuel imbalance corrections based on the NOx sensor data.

[0014] Another aspect of the disclosure provides an exhaust system including an engine control module (ECM) configured to perform operations including obtaining first oxygen sensor data from a first oxygen sensor, obtaining second oxygen sensor data from a second oxygen sensor, and obtaining nitrogen oxide (NOx) sensor data from a NOx sensor, performing catalyst condition diagnostic operations based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data, and performing fuel control adjustment operations to adjust one or more characteristics of the exhaust system based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data.

[0015] Implementations of the disclosure may include one or more of the following optional features. According to some implementations, the ECM is configured to obtain anhydrous ammonia (NH3) data from the NOx sensor and to obtain hydrocarbon (HC) data, carbon monoxide (CO), and particulate matter (PM) data based on the relationship between NOx, HC, CO, and PM from empirical data.

[0016] The ECM may be configured to iteratively perform catalyst condition diagnostic operations and fuel control adjustment based on NOx sensor data.

[0017] The ECM may be configured to iteratively perform catalyst condition diagnostic operations and fuel control adjustment based on NOx sensor data.

[0018] The fuel control adjustment operations may include engine air imbalance corrections and / or engine fuel imbalance corrections based on the NOx sensor data.

[0019] The ECM may be configured to receive tailpipe emissions data from the NOx sensor and, if necessary, implement target tailpipe NOx emissions control instead of stoichiometric fuel control.

[0020] The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will become apparent from the description and drawings and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure; they show: Fig. 1 is a functional diagram of a vehicle including a fuel system including a first example NOx sensor according to an example configuration; Fig. 2 is a functional diagram of a vehicle including a fuel system including a second example NOx sensor, according to an example configuration; Fig. 3 is a flow chart of a fuel system control process that controls the NOx sensor according to the Fig. 1 and Fig. 2 contains, according to different configurations; Fig. 4 is a flow chart of a process for improving catalyst condition diagnosis, which uses the NOx sensor according to the Fig. 1 and Fig. 2, according to different configurations; and Fig. 5 schematically shows a NOx sensor containing an oxygen pump cell and a nitrogen sensing cell.

[0022] Corresponding reference numerals indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION

[0023] Example configurations will now be described more fully with reference to the accompanying drawings. Example configurations are provided so that this disclosure will be thorough and will fully convey the scope of the disclosure to those of ordinary skill in the art. Specific details, such as examples of specific components, devices, and methods, are set forth in order to provide a thorough understanding of the configurations of the present disclosure. Those of ordinary skill in the art will appreciate that specific details need not be employed, that the example embodiments of the configurations may be embodied in many different forms, and that the specific details and example configurations should not be construed to limit the scope of the disclosure.

[0024] In the Fig. 1 and Fig. 2, a fuel system 100 is generally shown. According to certain configurations, the fuel system 100 is for a vehicle, which may be a motor vehicle. As will be appreciated, the vehicle may be any of a number of different types of motor vehicles, such as a sedan, station wagon, truck, or sport utility vehicle (SUV), and may have two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD), and / or various other types of vehicles. According to certain configurations, the vehicle may also include a truck, a watercraft, an aircraft, and / or one or more other types of vehicles. In addition, it is also recognized that the vehicle may include any number of other types of mobile platforms having a system such as the fuel system 100.

[0025] The fuel system 100 includes a controller 102 (also referred to as an engine control unit or engine control module) that includes a computer system. The computer system of the controller 102 includes a processor 104 and a memory 106. The processor 104 performs the computation and control functions of the controller 102 and may include any type of processor or multiple processors, individual integrated circuits such as a microprocessor, or any suitable number of integrated circuit devices and / or circuit boards that cooperate to perform the functions of a processing unit. During operation, the processor 104 executes one or more programs contained within the memory 106 and, as such, controls the general operation of the controller 102 and the computer system of the controller 102 in general in carrying out the processes described herein, such asof the method 300, which is described below in connection with . Fig. 3, and the procedure 400, which is discussed below in connection with Fig. 4 will be discussed further.

[0026] Memory 106 may be any suitable type of memory. For example, memory 106 may include various types of dynamic random access memory (DRAM), such as SDRAM, various types of static random access memory (SRAM), and various types of non-volatile memory (PROM, EPROM, and Flash). According to certain examples, memory 106 may be located on the same computer chip as processor 104 and / or may be co-located with processor 104.

[0027] The fuel system 100 includes an engine 108 that uses internal combustion, which is controlled to optimize fuel economy and emissions based on the requested load. The requested load may be based on a driver request or on autonomous input for torque and / or speed. The fuel system 100 includes a throttle actuator 110, an intercooler 112, an air intake filter, and a mass air flow sensor 114. According to various configurations, the engine 108 is a four-stroke internal combustion engine, with a piston in each cylinder executing an intake stroke, a compression stroke, a power stroke, and an exhaust stroke to drive the engine 108. Any number of cylinders may be included in the engine 108. The air intake 114 supplies air and controls the mass air flow to the cylinders via the throttle actuator 110.The fuel system supplies fuel to the cylinders and controls its timing and quantity via a number of fuel injectors, as further described below. The valve system includes a number of valves to control the flow of air / gases into and out of the cylinders. According to one configuration, the valves may have variable timing. The ignition system operates to control the timing of combustion in the cylinders and to initiate combustion in the cylinders. The exhaust system transports the combustion gases from the engine 14 to the atmosphere and may include aftertreatment devices.

[0028] Continue in the Fig. 1 and Fig. 2, the fuel system 100 includes an aftertreatment system 116, which, according to this configuration, includes a two-element arrangement with a first catalyst 118 and a second catalyst 120. According to other configurations, any suitable number of catalysts / elements may be included. The catalysts 118, 120 may be two-way or three-way catalysts. When the catalysts 118, 120 are configured as a two-way type, they convert two components in the exhaust stream, including CO and HC, into other components. When the catalysts 118, 120 are configured as a three-way type, they convert three components in the exhaust stream into other elements or compounds, including converting CO, HC, and nitrogen oxides into harmless elements or compounds. The catalysts 118, 120 may include catalysts such as platinum, palladium, or other materials.The rates at which the catalysts assist in the conversion of exhaust gases can vary with temperature. For example, the conversion rates may decrease at cold / cool temperatures. The fuel system 100 includes an exhaust system with an exhaust tailpipe 122 for venting the exhaust gases to the atmosphere.

[0029] The fuel system 100 includes a first oxygen sensor 124, a second oxygen sensor 126, and a nitrogen oxide (NOx) sensor 128, such as downstream of the aftertreatment system 116, as shown in Fig. 1. Alternatively, the NOx sensor 128 may be located in the aftertreatment system 116 between the first catalyst 118 and the second catalyst 120, as shown in Fig. 2. According to such configurations, the NOx sensor 128 would replace the second oxygen sensor 126.

[0030] The oxygen sensors 124, 126 measure the oxygen content of the exhaust gases leaving the engine 108, before the aftertreatment system 116, after the first catalyst 118, and before the second catalyst 120. The oxygen sensors 124, 126 provide data to determine the amount of remaining O2 in the gas stream at their locations in the exhaust system. The oxygen sensors 124, 126 may be a switching sensor or wide-range air-fuel ratio (WRAF) sensors. The signals from the oxygen sensors 124, 126 vary according to changing oxygen levels in the exhaust gas and provide for the determination of unburned oxygen in the exhaust gas. The signals from the oxygen sensors 124, 126 may also be used to determine the air-fuel ratio and other parameters at which the engine 108 is operated by the controller 102.

[0031] In the Fig. 1, Fig. 2 and Fig. 5, the NOx sensor 128 may include an oxygen pump cell 128a and a nitrogen sensing cell 128b. The NOx sensor 128 may receive a variety of data, including nitrogen oxide (NOx) data and O2 concentration. Additionally, ammonia (NH3) may be calculated based on the model from the NOx sensor.

[0032] In the Fig. 1 and Fig. 2, the fuel system 100 may include various other sensors 130, including, but not limited to, a mass air flow (MAF) sensor 130a, a throttle inlet absolute pressure (TIAP) sensor 130b, a manifold absolute pressure (MAP) sensor 130c, a coolant temperature sensor 130d, and an engine speed sensor 130e. The other sensors 130 may communicate with the controller 102 to transmit the data collected by the other sensors 130 to the controller 102.

[0033] In Fig. 3, a method or process 300 for diagnosing the fuel system 100 is generally shown. The process 300 may be performed by the controller 102 in conjunction with the various components controlled by and in communication with the controller 102. The process 300 includes a first step 302 in which the controller 102 determines a state of the engine 108 based on the oxygen sensors 124, 126, the NOx sensor 128, and the other sensors 130. In step 304, the controller 102 calculates the air flow rate. In step 306, the controller 102 estimates the air mass. In step 308, the controller 102 calculates the base fuel. In step 310, the controller calculates the fuel dynamics.

[0034] In step 312, the controller 102 determines a fuel control correction based on the state of the engine 108, the calculated air flow, the estimated air mass, the calculated base fuel, and the calculated fuel dynamics. In step 314, the controller 102 calculates an injector activation timing based on the fuel control correction and transmits the injector activation timing to the engine 108. The oxygen sensors 124, 126 continuously transmit data to the controller 102, which is then incorporated into the fuel control correction in step 312.

[0035] In step 320, the controller 102 calculates a current NOx offset based on the engine speed, engine torque, equivalence ratio, exhaust temperature, and ambient conditions. The controller 102 calculates the current NOx offset based on a tailpipe NOx baseline table or a target NOx emissions table based on the engine number and engine torque at an equivalence ratio equal to one (1), obtained in step 316. The controller 102 calculates the current NOx offset based on a NOx emissions correlation table based on the exhaust temperature, ambient temperature and pressure, and an equivalence ratio, obtained in step 318.

[0036] The controller 102 determines the current NOx offset in step 320 and then continuously incorporates this information into the fuel control correction in step 312. The result is a system and process that continuously receives data from multiple sensors (e.g., the oxygen sensors 124, 126, the NOx sensor 128, and the other sensors 130) to calculate the fuel injection of the fuel system 100 and make corrections based on this calculation or diagnosis.

[0037] In Fig.4, a method or process 400 for catalyst condition diagnosis based on a tailpipe NOx sensor combined with two O2 sensors is generally shown. Process 400 may be performed by controller 102 in conjunction with the various components controlled by and associated with controller 102. In step 402, controller 102 defines parameters based on, for example, engine speed, engine torque, air flow, engine coolant and exhaust gas temperature, ambient temperature and pressure, the tailpipe NOx sensor reading, etc. In step 404, controller 102 obtains from NOx sensor 128 the current NOx emission at a specific engine speed and torque, a specific equivalence ratio, and a specific exhaust gas temperature.

[0038] In step 408, the controller 102 obtains data from a WPA tailpipe NOx emissions table at various engine speeds and engine torques at an equivalence ratio equal to one (1), obtained by performing tests with the worst-performing acceptable catalysts. In step 410, the controller 102 obtains data from a NOx correction table for the ambient temperatures, ambient pressures, exhaust gas temperature, and the equivalence ratio. In step 412, the controller 102 obtains data from a BPU tailpipe NOx emissions table at various engine speeds and engine torques at an equivalence ratio equal to one (1), obtained by performing the tests with the best-performing unacceptable catalysts.

[0039] In step 414, the controller 102 determines the WPA NOx emissions at a specific engine speed and torque, a specific equivalence ratio, and a specific exhaust temperature. In step 416, the controller 102 determines the BPU NOx emissions at a specific engine speed and torque, a specific equivalence ratio, and a specific exhaust temperature.

[0040] In step 406, the controller 102 determines the current normalized NOx emission based on WPA and BPU: CN=C−BW−B, where CN is the current normalized NOx emission, C is the current NOx emission at the specific engine speed and torque, the specific equivalence ratio, and the specific exhaust gas temperature from the NOx sensor 128, W is the WPA NOx emission at the specific engine speed and torque, the specific equivalence ratio, and the specific exhaust gas temperature, and B is the BPU NOx emission at the specific engine speed and torque, the specific equivalence ratio, and the specific exhaust gas temperature.

[0041] In step 418, the controller 102 determines the normalized catalyst ratio at an estimated weighted moving average (EWMA) for a key cycle, which for robust diagnostics is at least a 10-minute run. In step 420, the controller 102 determines the normalized catalyst threshold for WPA and BPU, which is determined by a Six Sigma separation. In step 422, the controller 102 determines whether the current catalyst condition is pass or fail. In step 424, the controller 102 compares the catalyst status obtained from the catalyst diagnostics based on the two oxygen sensors 124, 126. In step 426, the controller determines a final conclusion for the catalyst condition for the key cycle.

[0042] The terminology used herein is for the purpose of describing specific example configurations only and is not intended to be limiting. As used herein, the singular articles "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, one or more other steps, one or more other operations, one or more other elements, one or more other components, and / or groups thereof.The method steps, processes, and operations described herein should not be construed as necessarily requiring their performance in the order discussed or illustrated, unless specifically identified as such. Additional or alternative steps may be used.

[0043] When an element or layer is described as being "on," "engaging with," "connected to," "attached to," or "coupled to" another element or layer, it may be directly on, engaging with, connected to, attached to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is described as being "directly on," "directly engaging with," "directly connected to," "directly attached to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" as opposed to "directly between," "adjacent" as opposed to "directly adjacent," etc.).The term “and / or” as used herein includes any combination of one or more of the associated listed elements.

[0044] The terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections. These elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as "first," "second," and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Consequently, a first element, component, region, layer, or section coulddiscussed below may be referred to as a second element, component, region, layer, or section without departing from the teachings of the example configurations.

[0045] In this application, including the definitions below, the term module may be replaced by the term circuit. The term module may refer to, be part of, or include an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; a memory (shared, dedicated, or group) that stores code executed by a processor; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

[0046] The term code, as used above, may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, and / or objects. The term shared processor includes a single processor that executes some or all of the code from multiple modules. The term group processor includes a processor that, in combination with additional processors, executes some or all of the code from one or more modules. The term shared memory includes a single memory that stores some or all of the code from multiple modules. The term group memory includes memory that, in combination with additional memory, stores some or all of the code from one or more modules. The term memory may be a subset of the term computer-readable medium.The term computer-readable medium does not encompass the transitory electrical and electromagnetic signals that propagate through a medium and can therefore be considered a tangible and non-transitory storage. Non-limiting examples of non-transitory storage include a tangible computer-readable medium, including non-volatile memory, magnetic memory, and optical memory.

[0047] The devices and methods described in this application may be implemented partially or entirely by one or more computer programs executed by one or more processors. The computer programs include processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer programs may also include and / or rely on stored data.

[0048] A software application (i.e., a software resource) may refer to computer software that causes a computing device to perform a task. According to some examples, a software application may be referred to as an "application," an "app," or a "program." Example applications include, but are not limited to, system diagnostic applications, system management applications, system maintenance applications, word processing applications, spreadsheet applications, messaging applications, media streaming applications, social networking applications, and gaming applications.

[0049] Non-transitory memory may include physical devices used to temporarily or permanently store programs (e.g., sequences of instructions) or data (e.g., program state information) for use by a computing device. The non-transitory memory may be volatile and / or non-volatile addressable semiconductor memory. Examples of non-volatile memory include, but are not limited to, flash memory and read-only memory (ROM) / programmable read-only memory (PROM) / erasable programmable read-only memory (EPROM) / electronically erasable programmable read-only memory (EEPROM) (which, for example, is typically used for firmware, such as boot programs).Examples of volatile memory include, but are not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), phase change memory (PCM), and disks or tapes.

[0050] These computer programs (also known as programs, software, software applications, or code) contain machine instructions for a programmable processor and may be implemented in a high-level procedural and / or object-oriented programming language and / or in an assembly / machine language. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, non-transitory computer-readable medium, device, and / or apparatus (e.g., magnetic disks, optical disks, memories, programmable logic devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal.The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0051] Various implementations of the systems and techniques described herein may be embodied in digital electronic and / or optical circuitry, integrated circuitry, specially designed ASICs (Application Specific Integrated Circuits), computer hardware, firmware, software, and / or combinations. These various implementations may include implementation in one or more computer programs executable and / or interpretable on a programmable system including at least one programmable processor, which may be a special-purpose or general-purpose processor, coupled to receive data and instructions from, and send data and instructions to, a memory system, at least one input device, and at least one output device.

[0052] The processes and logic flows described in this specification may be performed by one or more programmable processors, also referred to as data processing hardware, that execute one or more computer programs to perform functions by acting on input data and generating output. The processes and logic flows may also be performed by special-purpose logic circuitry, such as an FPGA (field-programmable gate array) or an ASIC (application-specific integrated circuit). Processors suitable for executing a computer program include, by way of example, both general-purpose and special-purpose microprocessors and any one or more processors of any type of digital computer. Generally, a processor receives instructions and data from read-only memory or random access memory, or both.The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to, one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks, for receiving data from them, sending data to them, or both. However, a computer is not required to include such devices. Computer-readable media suitable for storing instructions and data of a computer program include all forms of non-volatile memory, media, and storage devices, including, by way of example, semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.The processor and memory may be supplemented by or incorporated into special logic circuitry.

[0053] To provide interaction with a user, one or more aspects of the disclosure may be implemented in a computer having a display device, e.g., a CRT (cathode ray tube), an LCD (liquid crystal display monitor), or a touch screen, for displaying information to the user, and optionally a keyboard and a pointing device, e.g., a mouse or trackball, through which the user can provide input to the computer. Other types of devices may also be used to provide interaction with the user; feedback provided to the user may, for example, be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; while input from the user may be received in any form, including auditory, voice, or tactile input.Additionally, a computer may interact with a user by sending documents to and receiving documents from a device used by the user; e.g., by sending web pages to a web browser on a client device of the user in response to requests received from the web browser.

[0054] A number of implementations have been described. It is recognized, however, that various modifications may be made without departing from the spirit and scope of the disclosure.

[0055] Accordingly, other implementations are within the scope of the following claims.

[0056] The foregoing description has been provided for purposes of illustration and description. It is not intended to be exhaustive or limiting of the disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but are interchangeable and may be used in a selected configuration, even if not specifically shown or described. Furthermore, they may be varied in various ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

[1] Exhaust system for a vehicle comprising: a power machine; a three-way catalyst including a first catalyst and a second catalyst; an exhaust tailpipe adjacent to the three-way catalytic converter; a first oxygen sensor disposed between the engine and the catalyst; a second oxygen sensor disposed in the three-way catalyst; a nitrogen oxide sensor (NOx sensor) located in the exhaust tailpipe; and an engine control module (ECM) configured to receive first oxygen sensor data from the first oxygen sensor, second oxygen sensor data from the second oxygen sensor, and NOx sensor data from the NOx sensor, wherein the ECM is configured to perform catalyst condition diagnostic operations and fuel control adjustment operations to adjust one or more characteristics of the exhaust system based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data. [2] The exhaust system of claim 1, wherein the NOx sensor is located at or near the end of the exhaust tailpipe or after the second catalyst, and wherein the NOx sensor monitors the tailpipe emissions and provides feedback for the fuel control function based on the first oxygen sensor and the second oxygen sensor, and adjusts the fuel control based on the NOx sensor data. [3] The exhaust system of claim 1, wherein the ECM is configured to obtain ammonia (NH3) data from the NOx sensor and to obtain hydrocarbon (HC) data, carbon monoxide (CO) data, and particulate matter (PM) data based on the relationship between NOx, HC, CO, and PM from empirical data. [4] The exhaust system of claim 1, wherein the ECM is configured to perform the catalyst condition diagnostic operations during all engine operating conditions that combine or replace the use of a deceleration fuel cut event to perform the catalyst condition diagnostic operations with the first oxygen sensor and the second oxygen sensor. [5] The exhaust system of claim 1, wherein the ECM is configured to iteratively perform the catalyst condition diagnostic operations and the fuel control adjustment based on the NOx sensor data. [6] Exhaust system comprising: a power machine; a three-way catalyst including a first catalyst and a second catalyst; an exhaust tailpipe adjacent to the three-way catalytic converter; a first oxygen sensor disposed between the engine and the catalyst; a nitrogen oxide sensor (NOx sensor) located in the three-way catalyst; and an engine control module (ECM) configured to receive first oxygen sensor data from the first oxygen sensor, second oxygen sensor data from the NOx sensor, and NOx sensor data from the NOx sensor, wherein the ECM is configured to perform catalyst condition diagnostic operations and adjust one or more characteristics of the exhaust system based on at least the first oxygen sensor data, the second oxygen sensor data, and the NOx sensor data. [7] The exhaust system according to claim 6, wherein the NOx sensor is arranged between the first catalyst and the second catalyst. [8] The exhaust system of claim 6, wherein the ECM is configured to obtain ammonia (NH3) data from the NOx sensor and to obtain hydrocarbon (HC) data, carbon monoxide (CO) data, and particulate matter (PM) data based on the relationship between NOx, HC, CO, and PM from empirical data. [9] The exhaust system of claim 6, wherein the ECM is configured to perform the catalyst condition diagnostic operations during all engine operating conditions that combine or replace the use of a fuel cut event to perform the catalyst condition diagnostic operations with the first oxygen sensor and the second oxygen sensor. [10] The exhaust system of claim 6, wherein the ECM is configured to perform the catalyst condition diagnostic operations and iteratively adjust one or more characteristics of the exhaust system based on the NOx sensor data.

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