News Column

Researchers Submit Patent Application, "Exhaust Manifold Pressure Based Misfire Detection for Internal Combustion Engines", for Approval

August 7, 2014



By a News Reporter-Staff News Editor at Computer Weekly News -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors KAPPAGANTHU, Karthik (Bloomington, IN); Stroh, David (Columbus, IN), filed on January 14, 2013, was made available online on July 24, 2014.

The patent's assignee is Cummins Inc.

News editors obtained the following quote from the background information supplied by the inventors: "Engine manufacturers have developed techniques for constantly monitoring the operational characteristics of the engine to determine when engine operation is abnormal or outside of prescribed tolerances. Engine manufactures have sought approaches and methods to determine or predict when abnormal operations may occur in an attempt to meet the demand for increased internal combustion engine efficiency and improved emissions control. Similarly, having approaches that may identify early anomalies in operations may assist in preventing damage and avoiding potentially costly repairs to an internal combustion engine

"Engine cylinder misfire (i.e., misfire) is an example of one such event. Engine manufacturers seek to detect the occurrence of a misfire, for when detected, a misfire may be an early indication of a potential problem with the operation of the engine. For instance, a cylinder misfire can occur due to failed ignition of the fuel-air mixture within an engine cylinder (lack of combustion) or the incomplete ignition of the fuel-air mixture caused by too lean of a mixture (incomplete combustion). In operation, where such a misfire occurs, the affected engine performance is diminished, emissions are likely increased, and fuel economy is reduced. Similarly, if left uncorrected, a misfire may also result in damage to the engine and its components, including damage to the catalytic converter, for instance.

"Further, engine cylinder misfire detection is a requirement for On-Board Diagnostics II (OBD II). OBD II is a second generation of on-board self-diagnostic equipment requirements which provide for the ability to monitor engine components that can affect emission performance, such as misfires in engines. Typically, an OBD II system will also store important information about a detected malfunction, such as engine cylinder misfire and the faulted cylinder or component.

"Engine manufacturers have used a variety of approaches to detect engine misfires, but none of the prior art methods take into account a multitude of present operating conditions of an internal combustion engine including exhaust manifold pressure (EMP) with information from other sensor data such as engine speed, charge flow (or mass air flow (MAF)), Exhaust gas Recirculation (EGR) pressure, ambient pressure, turbine speed and turbine position, to detect an engine misfire.

"For example, U.S. Pat. No. 5,193,513 to Marko et al. discloses a misfire detection system for use in an internal combustion engine in which an exhaust pressure sensor, a position sensor for sensing the rotational position of the engine, and an analog-to-digital converter for digitizing an analog signal received from the pressure sensor are employed. The digitized pressure data is compared using a data classifier (i.e. pattern recognition system) that is trained to recognize data signatures of individually misfiring cylinders. To train the classifier, the engine is operated in a service bay and engine data is collected during both intentionally induced misfires and under normal conditions. This data is then presented to the data classifier in a training operation. Engine misfire detection systems such as the one disclosed in Marko, et al., however, fail to compare a multitude of engine operation characteristics to sensed engine cylinder peak pressures as a way of detecting partial or complete engine misfires.

"U.S. Pat. No. 3,965,677 to Goto et al. discloses a misfire detecting apparatus in which the suction pressure of an engine is detected and used to calculate a threshold level wherein a cylinder misfire is declared if the exhaust gas pressure exceeds this threshold level.

"U.S. Pat. No. 3,983,754 to Deguchi et al. discloses an apparatus for detecting misfires in a multi-cylinder internal combustion engine in which pressure responsive devices are provided in the branches of the exhaust manifold or exhaust ports and the outputs of these devices are compared to detect an engine cylinder misfire.

"U.S. Pat. No. 4,567,755 to Ootsuka et al. discloses an ignition/misfire detector for an internal combustion engine in which a pressure detection unit is used to detect changes in combustion pressure in the engine and an ignition/misfire detection unit is used to determine the occurrence of an engine ignition misfire.

"U.S. Pat. No. 3,924,457 to Oshima et al. discloses a misfire detecting device for an internal combustion engine in which an exhaust gas introducing tube is provided adjacent to an exhaust port in an exhaust passage to provide exhaust gas to a pressure transducer disposed at one end of the exhaust gas introducing tube to determine pressure fluctuation which may indicate a possible engine cylinder misfire.

"In OBD II systems, many current monitors use crank speed fluctuations in order to detect misfires. However, it is generally recognized that using crank speed fluctuations are dependent upon power train and vehicle dynamics. Such dependency, including that using engine speed, is limiting however as the portability of detection across various applications is unavailable and the inputted data is often negatively influenced by driveline dynamics.

"These prior methods of detecting engine cylinder misfire are devoid of the unique approach to employ a multitude of present engine operating conditions, including that of utilizing a relationship between in-cylinder pressure, changes in EMP fluctuations and other operating conditions to provide an efficient engine cylinder misfire detection system.

"A novel engine cylinder misfire detection system and improvement over the prior art is disclosed in U.S. Pat. No. 5,392,642 to Tau, a patent which is assigned to Cummins Engine Company, Inc., the same assignee of the present invention. This patent discloses an engine cylinder misfire system that uses a sensor to monitor an engine cylinder for all engine cycles and to provide an average of the detected output for each cylinder. Furthermore, the engine speed and fuel rate of the internal combustion engine are used to provide a more effective engine cylinder misfire detection system. Nevertheless, the invention disclosed in the Tau patent is directed to a system for detecting low power in at least one cylinder of a multi-cylinder engine. Furthermore, this application discloses the use of multiple pressure sensors, specifically one sensor for each cylinder to provide engine misfire detection.

"A further novel engine cylinder misfire detection system and improvement over the prior art is disclosed in U.S. Pat. No. 6,243,641 to Andrews et al., incorporated herein by reference, which is a patent assigned to Cummins Engine Company, Inc., the same assignee of the present invention. This patent discloses an engine cylinder misfire detector system which calculates and compares a minimum pressure value, using a pressure sensing means for sensing the peak pressure of the exhaust gas flowing through the exhaust and operating characteristics of the internal combustion engine, to determine if an engine cylinder misfire has occurred.

"Other approaches have also been set forth, but these methods also are devoid of detecting engine cylinder misfire utilizing a relationship between in-cylinder pressure, changes in EMP fluctuations and other operating conditions to provide an efficient engine cylinder misfire detection system that it operable over a variety of operating environments (i.e., power trains, vehicles, etc.), may be calibrated across different applications, and is reliable over a variety of operating conditions.

"Therefore, the inventor has recognized a need for an engine cylinder misfire detection system that detects changes in EMP fluctuations, compares the EMP fluctuations with diagnostic thresholds determined with other information obtained from other engine sensor data, and determines whether a cylinder misfire has occurred. Further, the inventor has recognized a need for developing a method of monitoring and detecting EMP fluctuations to determine the occurrence of a misfire."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "It is an object of the present invention to provide an improved system and method for determining when an engine cylinder misfire occurs in an internal combustion engine.

"It is an object of the present invention to provide a method of monitoring and detecting EMP fluctuations in combination with one or more sensed engine characteristics to determine the occurrence of a misfire.

"It is a still further object of the present invention to provide a system and method for accurately and reliably detecting an engine cylinder misfire by analyzing changes to EMP fluctuations with in-cylinder pressure and other operating conditions of the engine to determine when an engine cylinder misfires occurs.

"It is a further object of the invention to provide for one or more processes to detect a misfire condition of the cylinder of an engine as either being present or not present in relation to determined fresh air flow (FAF), engine type, engine data inputs, and analytical determinants using the present invention, where the one or more processes include an estimated exhaust manifold pressure estimation process (EEMPP) or a centroid projection process (CPP).

"As used herein, FAF is intended to further include but not be limited by engine characteristics and information (hereinafter 'engine characteristics,' 'information,' and similar) regarding engine load, such as fuel quantity, mass charge flow (MCF), fresh air flow, etc. and may be depicted as FAF, FAF/MCF, or similar, interchangeably. More particularly, for non-stoic engine applications, fuel quantity may be used as a direct substitute for FAF. Similarly, for estimated Fresh Air Flow (EFAF), EFAF is intended to further include but not be limited by engine characteristics and information regarding estimated engine load, such as estimated fuel quantity, estimated mass charge flow (EMCF), estimated fresh air flow, related thresholds, etc. and may be depicted or used as estimated load threshold, EFAF, EFAF/EMCF, or similar, interchangeably.

"As used herein, a sensed engine characteristic may include but not be limited to any of engine characteristics, information or similar measured by a sensor or otherwise sensed during operation of the engine, including but not limited to: EMP, FAF, engine speed, MAF, fueling Exhaust Gas Recirculation (EGR) pressure, ambient pressure, turbine speed, turbine position, and similar.

"The present invention fulfills these needs and has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available technologies. The present invention provides a method, system and computer program product for determining a misfire condition of an engine cylinder over known approaches.

"In one embodiment, the present invention provides for a method for detecting an engine cylinder misfire in an internal combustion engine by comparing a first load variable (FLV) with a first estimated load variable (FELV) for a first cylinder of the engine and initiating a first process. The embodiment preferably further measures an exhaust manifold pressure (EMP), using the first process, calculates an operating value (OV) in relation to one or more data inputs of engine characteristics and a comparative value (CV) associated with a threshold value. Further, the OV and the CV are compared and a misfire condition is detected for the first cylinder. Preferably, the first process in an embodiment is one of an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), for which if the FLV is less than the FELV, the process initiated is the EEMPP. Additionally, it is preferred that the one or more data inputs include at least one of: EMP, engine speed, mass air flow (MAF), EGR pressure, ambient pressure, turbine speed and turbine position. For the avoidance of doubt, the term FLV is intended to be inclusive of the descriptor FAF/MCF and the term FELV is intended to be inclusive of the term EFAF/EMCF. Further, in one or more preferred embodiments, the FLV is one or more of an engine characteristic, engine load, fuel quantity, mass charge flow (MCF), fresh air flow (FAF), flow rate, and the FELV is one or more of an estimated engine characteristic, estimated engine load, estimated fuel quantity, estimated mass charge flow (EMCF), estimated fresh air flow (EFAF), estimated flow rate, associated with the FLV.

"In a further embodiment, the present invention provides for a method for detecting an engine cylinder misfire in an internal combustion engine by comparing a FAF with an EFAF for a first cylinder of the engine and initiating a first process.

"In another embodiment the present invention provides for a system for identifying a misfire condition of an engine cylinder in an internal combustion engine. The system comprises: at least one load estimate providing a first load variable (FLV); at least one pressure sensor operatively coupled to detect an exhaust manifold pressure (EMP); at least one data sensor operatively coupled to detect at least one or more data inputs of engine characteristics of the engine; and a control system for the engine having an exhaust gas output. The embodiment further includes the control system having a plurality of actuation controllers being in communication with the at least one load estimate, the at least one pressure sensor, and the at least one data sensor, through one or more actuation controllers; a data processor in communication to receive data sensed by the at least one load estimate, the at least one pressure sensor, and the at least one data sensor. Preferably the processor utilizes a first process to calculate an operating value (OV), the first process being determined in relation to comparing the received data sensed and estimated associated data, and a comparative value (CV), associated with a threshold value; comparing the OV and the CV, and, detecting a misfire condition for the cylinder.

"In the preferred embodiment the present invention further provides for first process being one of an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP).

"In a further embodiment, the present invention provides for a computer program product stored on a computer usable medium for determining a misfire condition of an internal combustion engine having one or more cylinders, comprising, a computer readable program for causing a computer to control an execution of an application within a memory control device in operable communications with an engine. Preferably, the computer readable program when executed by a computer provides for: determining a first process by comparing if a first load variable (FLV) is greater than a first estimated load variable (FELV) for a first cylinder of the engine; determining an exhaust manifold pressure (EMP), executing the first process and calculating an operating value (OV) in relation to the one or more data inputs of engine characteristics, and a comparative value (CV) associated with a threshold value; comparing the OV and the CV, and, detect a misfire condition for the first cylinder. Preferably, the present invention may be configured for use in, as or with a vehicle, an engine (diesel, spark-ignited, gasoline, natural gas, hybrid, etc.), a diagnostic tool, a computer system or similar.

"In a further embodiment, the present invention provides for a method of monitoring and detecting EMP fluctuations in combination with one or more sensed engine characteristics to determine an engine cylinder misfire in a cycle of an internal combustion engine having at least one cylinder. The method includes measuring an EMP, determining a signal filtered output from the EMP using a signal filter, and computing a root mean square (RMS) of one or more extracted relevant frequencies. Preferably the method also includes identifying a predetermined misfire threshold, comparing the computed RMS with the misfire threshold, and detecting a misfire condition for the cycle. Further the method may also detect EMP fluctuations in combination with one or more sensed engine characteristics to determine the occurrence of a misfire condition.

"In still a further preferred embodiment, a diesel engine configured to detect an engine cylinder misfire is provided. In the preferred embodiment, the engine comprises logic for: comparing a first load variable (FLV) with an first estimated load variable (FELV) for one or more cylinders of the engine and initiating a first process being of one of an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP); measuring an exhaust manifold pressure (EMP), using the first process, calculating an operating value (OV) in relation to one or more data inputs of engine characteristics and a comparative value (CV) associated with a threshold value; comparing the OV and the CV, and, detecting a misfire condition for the one or more cylinders of the diesel engine.

"In a preferred embodiment, an engine having logic of the present invention is able to determine a relationship between the FLV and FELV, where wherein if the FLV is less than the FELV, the initiated first process initiated is the EEMPP, and wherein if the FLV is not less than the FELV, the logic initiated as the first process is the CPP.

"Further embodiments, forms, objects, features, advantages, aspects, and benefits of the present application shall become apparent from the detailed description and drawings included herein.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is an illustration of a block diagram of one form of the control system 100 of the present invention in accordance with an embodiment of the present invention;

"FIG. 2A is a block diagram of the method of the present invention in accordance with one or more embodiments thereof;

"FIG. 2B is a block diagram of an implementation of a method of the present invention in accordance with one or more embodiments thereof;

"FIG. 3 is a block diagram of additional processing of a method of the present invention involving the step of an estimated exhaust manifold pressure process (EEMPP), in accordance with one or more embodiments thereof;

"FIG. 4 is a block diagram of additional processing of a method of the present invention involving the step of a centroid projection process (CPP), in accordance with one or more embodiments thereof;

"FIG. 5 depicts representative results using the present invention, in accordance with one or more embodiments thereof; and,

"FIG. 6 depicts an overall view of a spark ignition type internal combustion engine having a controller means in communication with the spark igniter, fuel injector and an EGR configuration capable of operating with the present invention.

"FIG. 7 is a flow chart of a slow diagnostic method in accordance with an embodiment.

"FIG. 8 sets forth the results of magnitude versus frequency and of phase versus frequency, in accordance with an aspect of the present invention.

"FIG. 9 sets forth a flowchart of the method of a preferred embodiment of the present invention in which one or more sensed engine characteristics are used to determine an engine cylinder misfire in an internal combustion engine having at least one cylinder.

"FIG. 10 sets forth a depiction of the EMP, the notch filter output, the notch filter residue, and the effect of misfire."

For additional information on this patent application, see: KAPPAGANTHU, Karthik; Stroh, David. Exhaust Manifold Pressure Based Misfire Detection for Internal Combustion Engines. Filed January 14, 2013 and posted July 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1026&p=21&f=G&l=50&d=PG01&S1=20140717.PD.&OS=PD/20140717&RS=PD/20140717

Keywords for this news article include: Cummins Inc.

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