DESC:FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003

COMPLETE SPECIFICATION
[See section 10 and rule 13]

TITLE: “SYSTEMS AND METHODS FOR DIAGNOSING COMPRESSION BRAKE SYSTEMS”

Name and Address of the Applicant:
Cummins Inc. of 500, Jackson Street, Columbus, Indiana 47201, United States of America
Nationality: USA

The following specification particularly describes the nature of the invention and the manner in which it is to be performed.

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SYSTEMS AND METHODS FOR DIAGNOSING COMPRESSION BRAKE SYSTEMS
CROSS-REFERENCE TO OTHER APPLICATION
[0001] This application claims priority to Indian Patent Application No. 202041022134 titled “SYSTEMS AND METHODS FOR DIAGNOSING COMPRESSIONS BRAKE SYSTEMS,” filed May 27, 2020, which is incorporated herein by reference in its entirety and for all purposes.
TECHNICAL FIELD
[0002] The present disclosure relates to systems and methods for diagnosing a compression braking system.
BACKGROUND
[0003] An internal combustion engine may be equipped with a compression braking system that aids in retarding a speed of the vehicle, which may be used with or without external braking systems. In operation, the compression braking system alters a timing of engine valves during operation of the internal combustion engine. For example, during a compression stroke, an exhaust valve opens rather than remaining closed thereby releasing much of the compressed air that would have been used to output power from the engine. As such, an expansion stroke is driven by much less compressed air than during normal operation, thereby generating negative power.
SUMMARY
[0004] One embodiment relates to a system that includes a controller coupled to a compression braking system associated with an engine. The controller includes at least one processor coupled to a memory storing instructions that, when executed by the at least one processor, cause the controller to perform operations including: activate compression braking via the compression braking system associated with the engine; determine a value of a parameter associated with operation of the compression braking system associated with the engine; retrieve a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended; compare the value of the parameter to the benchmark value of the parameter; retrieve a diagnostic threshold indicative of a healthy compression braking system; and responsive to determining that a result of the comparison does not align with the diagnostic threshold, provide an alert.
[0005] Another embodiment relates to a method for diagnosing a compression braking system of an engine. The method includes: determining a value of a parameter associated with operation of a compression braking system of an engine; retrieving a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended; comparing the value of the parameter to the benchmark value of the parameter; retrieving a diagnostic threshold indicative of a healthy compression braking system; and responsive to determining that a result of the comparison does not align with the diagnostic threshold, providing an alert.
[0006] Yet another embodiment relates to a system. The system includes a compression braking system associated with an engine; and a controller coupled to the compression braking system, the controller configured to: provide a command to activate compression braking via the compression braking system associated with the engine; determine a value of a parameter associated with operation of the compression braking system of the engine; retrieve a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended; compare the value of the parameter to the benchmark value of the parameter; retrieve a diagnostic threshold indicative of a healthy compression braking system; and responsive to determining that a result of the comparison does not align with the diagnostic threshold, provide an alert.
[0007] This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements.
BRIEF DESCRIPTION OF THE FIGURES
[0008] FIG. 1 is a schematic diagram of an engine system, according to an example embodiment.
[0009] FIG. 2 is a schematic view of a controller of the engine system of FIG. 1, according to an example embodiment.
[0010] FIG. 3A is a plot of engine speed versus experimental values of charge pressure and charge flow rate for an engine with a functional compression braking system and an engine with a non-functional compression braking system, according to an example embodiment.
[0011] FIG. 3B is a plot of the engine speed versus differences in values of charge pressure and charge flow rate for an engine with a functional compression braking system and an engine with a non-functional compression braking system, according to an example embodiment.
[0012] FIG. 4 is a plot of engine speed versus experimental values for exhaust pressure for an engine with a functional compression braking system and an engine with a non-functional compression braking system, and of the difference of those values, according to an example embodiment.
[0013] FIG. 5A is a plot of engine speed versus experimental values of torque and power output for an engine with a functional compression braking system and an engine with a non-functional compression braking system, according to an example embodiment.
[0014] FIG. 5B is a plot of engine speed versus the differences in values of torque and power output between an engine with a functional compression braking system and an engine with a non-functional compression braking system, according to an example embodiment.
[0015] FIG. 6A is a plot of engine speed versus benchmark values of charge pressure for an engine with a functional compression braking system, experimental values of charge pressure for an engine with a non-functional compression braking system, and an integral of the difference between the two values over time, according to an example embodiment.
[0016] FIG. 6B is a plot of engine speed versus benchmark values of charge pressure for an engine with a functional compression braking system, experimental values of charge pressure for an engine with a functional compression braking system, and an integral of the difference between the two values over time, according to an example embodiment.
[0017] FIG. 7 is a flow diagram of a method for diagnosing a compression braking system, according to an example embodiment.
DETAILED DESCRIPTION
[0018] Following below are more detailed descriptions of various concepts related to, and implementations of, methods, apparatuses, and systems for diagnosing a functionality of a compression braking system of an engine. Before turning to the figures, which illustrate certain exemplary embodiments in detail, it should be understood that the present disclosure is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting.
[0019] Referring to the figures generally, the various embodiments disclosed herein relate to systems, apparatuses, and methods for diagnosing a compression braking system of an engine system. Compression braking is an important feature in engines, as utilizing compression braking reduces maintenance costs associated with maintaining a service brake system. However, current systems for diagnosing the compression braking system on a newly manufactured engine are lacking, as current diagnosis systems rely on inaccurate manual measurements and inconsistent standards across engine types and test cells. Further, current testing methods for compression braking systems generally require the labor of skilled human testers. In this regard, end of line testing (i.e., test cells where engines are checked before leaving the manufacturing facility) do not produce flags or other indicators regarding inoperability of the compression braking system. This results in engineering personnel needing to investigate operation of the compression braking system to identify a failure or potential failure. When engines are in use after being installed for various applications (e.g., in a vehicle, as part of a stationary gen-set, etc.), there is a lack of conclusive flags (e.g., fault codes, dashboard indications, etc.) being annunciated to the operator. Accordingly, resolving compression brake failures in the field also takes more time to resolve. Technically, the ability to identify and potentially resolve failure conditions in a compression braking system would be beneficial to reduce engine downtime and reduce expenditure of resources needed for typical troubleshooting exercises among other potential benefits.
[0020] The present disclosure relates to systems and methods for diagnosing a compression braking system of an internal combustion engine. A controller is coupled to an engine that is coupled to a plurality of sensors. If the sensors are real, the sensors are positioned throughout the engine and related components. The sensors, either real or virtual, acquire data indicative of operation of the compression braking system, which includes monitoring the “breathing” capability of the engine (i.e. the flow of air and exhaust through combustion chambers). As a result, the controller is structured or configured to determine a value of a parameter associated with a compression braking system of an engine (such as a pressure or flow of the charge, pressure of the exhaust, etc.), retrieve a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended, compare the value of the parameter to the benchmark value of the parameter, retrieve a diagnostic threshold indicative of a healthy compression braking system, and responsive to determining that a result of the comparison does not align with the diagnostic threshold, provide an alert. These and other features and benefits are described more fully herein below.
[0021] Referring now to FIG. 1, an engine system 10 having an engine 12, a turbocharger that is shown as a compressor 22 and a turbine 23, and a controller 26 is shown according to an example embodiment. According to one embodiment, the engine system 10 is embodied within a vehicle. The vehicle may include an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up truck, etc.), sedans, coupes, tanks, airplanes, boats, and any other type of vehicle. Based on these configurations, various additional types of components may also be included in the system, such as a transmission, one or more gearboxes, pumps, actuators, or anything that is powered by an engine.
[0022] The engine 12 may be any type of engine that can operate in conjunction with a compressing braking system. Thus, as shown here, the engine 12 may be an internal combustion engine (e.g., gasoline, natural gas, or diesel engines), a hybrid engine (e.g., a combination of an internal combustion engine and an electric motor), and/or any other suitable engine. In the example shown, the engine 12 is structured as a compression-ignition engine powered by diesel fuel. The engine 12 has a cylinder 14 that receives fuel (e.g., from a fuel injector, from a fuel supply, etc.) and air (e.g., from the turbocharger). The cylinder 14 includes an intake valve 15 that selectively opens to receive air into the cylinder 14 and an exhaust valve 16 that selectively opens to expel exhaust gases from the cylinder 14. The internal combustion engine 12 also has a piston positioned with the cylinder 14. The combustion of fuel within the cylinder 14 causes translation of the piston, and the internal combustion engine 12 is configured to selectively transform translation of the piston into mechanical energy that can be harvested for use in, for example, rotating a driveshaft that drives wheels of a vehicle housing the engine system 10.
[0023] While only one cylinder is depicted, it should be understood that the engine 12 may include a second cylinder, a third cylinder, a fourth cylinder, and additional other cylinders such that the engine 12 has a target number of cylinders and is tailored for a target application. For example, the engine 12 may include six, eight, ten, twelve, sixteen, twenty, or other numbers of cylinders and an equal number of pistons. The arrangement of the cylinders may be in any of a variety of arrangements, such as an inline configuration, a v-configuration, a w-configuration, etc. Further, in addition to the intake valve 15 and the exhaust valve 16, the cylinder 14 may include a second intake valve, a second exhaust valve, a third intake valve, a third exhaust valve, and any additional valves such that the cylinder 14 has a target number of intake valves and exhaust valves and is tailored for a target application.
[0024] The engine 12 operates on a cycle. In an exemplary embodiment, the cycle is a 4-stroke cycle that includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, in that order. It is understood that while the cycle of the engine 12 is a 4-stroke cycle in this exemplary embodiment, the disclosure should not be read as limited to a 4-stroke cycle and should be read as applicable to a 2-stroke or other cycle.
[0025] The engine system 10 is shown to further include a compression braking system 11. The compression braking system 11 is configured to be engaged or disengaged by an operator of the engine system 10 or according to a control scheme implemented by the controller 26. When the compression braking system 11 is disengaged, the engine 12 does not utilize compression braking. When the compression braking system 11 is engaged, the exhaust valve 16 is opened during the compression stroke of the 4-stroke cycle, releasing some of the compressed or soon-to-be-compressed air. As such, there is less translation of the piston generated by the expansion stroke and, therefore, less energy harvested for rotating the driveshaft, which, in turn, retards the vehicle.
[0026] The compression braking system 11 may utilize any number of cylinders, such that the exhaust valve(s) is opened during the compression stroke for some cylinders but remains closed for other cylinders. If more cylinders are utilized by the compression braking system 11, more negative power (i.e., amount of braking) is generated because more of the compressed or soon-to-be-compressed air is released. The number of cylinders utilized by the compression braking system 11 may be determined by the operator when the compression braking system 11 is engaged, or by the controller 26 according to the control scheme. In some embodiments, the number of cylinders utilized remains the same during the entire length of time that the compression braking system 11 is utilized. In other embodiments, the number of cylinders utilized changes based on demands on the compression braking system 11 (e.g., the number of cylinders utilized increases if more braking is requested).
[0027] Products of the combustion process (i.e., exhaust gas and discharged air from the compression braking) are discharged from the cylinder 14 via the exhaust valve 16 and expelled into the turbine 23 through an exhaust passage. The turbine 23 is mechanically coupled to the compressor 22 through, for example, a shaft, forming the turbocharger. The exhaust gas and air discharged from the cylinder 14 may drive the turbine 23 to rotate, which may in turn drive the compressor 22 to compress the air supplied to the engine 12. A wastegate 24 can enable part of the exhaust gas and discharged air to bypass the turbine 23, such that less energy is available to the turbine, which, in turn, reduces the power transferred to the compressor 22 and reduces the pressure of the air supplied to the engine 12. However, in some embodiments, the turbocharger may be omitted from the engine system 10. In those embodiments, the engine is naturally aspirated, meaning that the air/fuel mixture is drawn into the cylinder 14 by atmospheric pressure and the slight vacuum created by the downward movement of the piston during the intake stroke.
[0028] When the compression braking system 11 is engaged and working as intended, an increased quantity of exhaust gas and air is discharged into the turbine 23, due to the exhaust valve 16 being opened twice during the four-stroke cycle (rather than once as in the four-stroke cycle when the compression braking system 11 is disengaged). This increased quantity of discharge increases a volumetric efficiency of the engine system 10, causing an increased flow through the turbine 23. This increased flow through the turbine 23 leads to higher expansion ratios for the turbine 23, which, in turn, lead to greater exhaust pressure at an inlet to the turbine 23. Increased flow through the turbine 23 also increases the amount of power transferred to the compressor 22, thereby increasing boost pressure from the compressor 22. An increase in boost pressure from the compressor 22 means that a pressure and a flow rate of the charged air at the intake valve 15 is greater.
[0029] In some embodiments, the engine may be coupled to an aftertreatment system configured to treat exhaust gases expelled from the engine. The aftertreatment system is structured to receive the exhaust gas and reduce components in the exhaust gas to less harmful compounds prior to emission of the exhaust gas into the atmosphere. The aftertreatment system may include a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction system, a reductant dosing system, and one or more other components among one or more sensors.
[0030] As also shown, a variety of sensors 30 are included in the engine system 10. The sensors 30 are coupled, particularly communicably coupled, to the controller 26, such that the controller 26 can monitor and acquire data indicative of operation of the system 10. As shown, the system 10 includes flow rate sensors 2, pressure sensors 4, torque sensors 6, and engine sensors 8. The flow rate sensors 2 acquire data indicative of or, if virtual, determine an approximate flow rate of the exhaust gas and/or charged air at or approximately at their disposed location. The pressure sensors 4 acquire data indicative of or, if virtual, determine an approximate pressure of the exhaust gas and/or charged air at or approximately at their disposed location. The torque sensors 6 acquire data indicative of or, if virtual, determine an approximate torque of the internal combustion engine 12. If the torque sensor 6 is virtual, the torque sensor 6 may determine the torque of the engine 12 as a function of engine 12 speed, exhaust pressure at the intake valve 15, and exhaust pressure at the exhaust valve 16. The engine sensors 8 acquire data indicative of or, if virtual, determine approximate data indicative of operation of the engine 12. The operational data regarding the engine 12 may include, but are not limited to an engine speed, a power output and load, etc. It should be understood that the depicted locations, numbers, and type of sensors is illustrative only. In other embodiments, the sensors 30 may be positioned in other locations, there may be more or less sensors than shown, and/or different/additional sensors may also be included with the system 10 (e.g., an ambient air sensor, a temperature sensor, etc.). Those of ordinary skill in the art will appreciate and recognize the high configurability of the sensors 30 in the system 10.
[0031] Because there are various sensed values (e.g. charge pressure, charge flow, exhaust pressure, etc.) that respond directly to operation of the compression braking system 11, the controller 26 can determine and monitor a health and operating condition of the compression braking system 11 through an analysis of these sensed values. The health of the compression braking system 11 refers to an ability of the compression braking system 11 to operate as intended. A healthy compression braking system indicates that the compression braking system is properly functioning. Conversely, if the health of the compression braking system is poor, that indicates that the compression braking system is not properly functioning. For example, if the compression braking system 11 is engaged but the charge pressure of air at the intake valve 15 is not increasing or is increasing to a lesser extent than expected, there may be an issue with the health of the compression braking system 11, such that the compression braking system may not be properly retarding the engine 12). As described herein, the controller 26 may monitor various parameters of the engine system to determine whether the compression braking system is healthy (operating as intended) or unhealthy or likely unhealthy.
[0032] The healthy determination may be based on one data point relative to the associated data point for a healthy compression braking system (e.g., a comparison of charge pressures). In other embodiments, the healthy determination may be based on two or more data points (e.g. a comparison of charge pressures and a comparison of exhaust pressures) relative to the associated data points for a healthy compression braking system. The data point(s) may be specified by a number of factors, including but not limited to, number of cylinders utilized by the compression braking system 11, air density at the inlet of the compressor 22, etc.
[0033] As described herein, the controller 26 utilizes one or more values to diagnose the compression braking system. Examples of sensed values that respond directly to a functioning compression braking system 11 include, but are not limited to, charge flow rate of air at the intake valve 15, exhaust pressure at the exhaust valve 16, and engine torque. In addition, monitoring at only a single instance in time would lead to an unreasonable number of false faults (or, alternatively, missed positives). Accordingly, incorporating a cumulative summation (Cusum) function or an integral serves to absorb instantaneous noise and to monitor a value over a period of time.
[0034] Another sensed value responsive to functioning compression braking system 11 is a torque of the engine 12. Because a functional compression braking system 11 is retarding the engine 12 by reducing an amount of power transferred to a rotating cam shaft, a functional compression braking system 11 can be thought of as increasing a negative torque provided by the engine. As such, by monitoring the torque produced by the engine 12 when the compression braking system 11 is engaged, the controller 26 can determine whether the compression braking system 11 is functional (also referred to as operating as intended or designed). In some embodiments, the torque is sensed by a real sensor. In other embodiments, the torque is determined or estimated by a virtual sensor that bases the determination, in part, on exhaust pressure, charge pressure, and engine speed. Engine power output, which is defined as the product of engine speed and engine torque, is similarly responsive to a functional compression braking system and can be similarly monitored.
[0035] As the components of FIG. 1 are shown to be embodied in the system 10, the controller 26 may be structured as one or more electronic control units (ECU). The controller 26 may be separate from or included with at least one of a transmission control unit, an exhaust aftertreatment control unit, a powertrain control module, an engine control module, etc. The function and structure of the controller 26 is described in greater detail in FIG. 2.
[0036] Components of the vehicle may communicate with each other or foreign components (e.g., a remote operator) using any type and any number of wired or wireless connections. Communication between and among the controller 26 and the components of the vehicle may be via any number of wired or wireless connections (e.g., any standard under IEEE 802). For example, a wired connection may include a serial cable, a fiber optic cable, a CAT5 cable, or any other form of wired connection. Wireless connections may include the Internet, Wi-Fi, cellular, radio, Bluetooth, ZigBee, etc. In one embodiment, a controller area network (CAN) bus provides the exchange of signals, information, and/or data. The CAN bus includes any number of wired and wireless connections that provide the exchange of signals, information, and/or data. The CAN bus may include a local area network (LAN), or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
[0037] Referring now to FIG. 2, a schematic diagram of the controller 26 of the engine system of FIG. 1 is shown according to an example embodiment. As shown in FIG. 2, the controller 26 includes a processing circuit 51 having a processor 52 and a memory 53, a quantity circuit 55, a threshold circuit 56, and a communications interface 54. The controller 26 is structured to diagnose the compression braking system 11. By determining the differences (if any) between sensed values and pre-determined and preset operational threshold values for various compression braking parameters and comparing these differences against a predefined or preset diagnostic threshold. Based on this comparison, the controller 26 determines whether the compression braking system 11 is functioning as intended or if the compression braking system is malfunctioning, and takes action in response.
[0038] In one configuration, the quantity circuit 55 and the threshold circuit 56 are embodied as machine or computer-readable media that is executable by a processor, such as processor 52. As described herein and amongst other uses, the machine-readable media facilitates performance of certain operations to enable reception and transmission of data. For example, the machine-readable media may provide an instruction (e.g., command, etc.) to, e.g., acquire data. In this regard, the machine-readable media may include programmable logic that defines the frequency of acquisition of the data (or, transmission of the data). The computer readable media may include code, which may be written in any programming language including, but not limited to, Java or the like and any conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program code may be executed on one processor or multiple remote processors. In the latter scenario, the remote processors may be connected to each other through any type of network (e.g., CAN bus, etc.).
[0039] In another configuration, the quantity circuit 55 and the threshold circuit 56 are embodied as hardware units, such as electronic control units. As such, the quantity circuit 55 and the threshold circuit 56 may be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc. In some embodiments, the quantity circuit 55 and the threshold circuit 56 may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of “circuit.” In this regard, the quantity circuit 55 and the threshold circuit 56 may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on). The quantity circuit 55 and the threshold circuit 56 may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. The quantity circuit 55 and the threshold circuit 56 may include one or more memory devices for storing instructions that are executable by the processor(s) of the quantity circuit 55 and the threshold circuit 56. The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory 53 and processor 52. In some hardware unit configurations, the quantity circuit 55 and the threshold circuit 56 may be geographically dispersed throughout separate locations in the vehicle. Alternatively and as shown, the quantity circuit 55 and the threshold circuit 56 may be embodied in or within a single unit/housing, which is shown as the controller 26.
[0040] In the example shown, the controller 26 includes the processing circuit 51 having the processor 52 and the memory 53. The processing circuit 51 may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to quantity circuit 55 and the threshold circuit 56. The depicted configuration represents the quantity circuit 55 and the threshold circuit 56 as machine or computer-readable media. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments where the quantity circuit 55 and the threshold circuit 56, or at least one circuit of the quantity circuit 55 and the threshold circuit 56, is configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure.
[0041] The processor 52 may be implemented as a single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor may be a microprocessor, or, any conventional processor, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, the one or more processors may be shared by multiple circuits (e.g., quantity circuit 55 and the threshold circuit 56 may comprise or otherwise share the same processor which, in some example embodiments, may execute instructions stored, or otherwise accessed, via different areas of memory). Alternatively or additionally, the one or more processors may be structured to perform or otherwise execute certain operations independent of one or more co-processors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure.
[0042] The memory 53 (e.g., memory device, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory 53 may be communicably connected to the processor 52 to provide computer code or instructions to the processor 52 for executing at least some of the processes described herein. Moreover, the memory 53 may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory 53 may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.
[0043] The quantity circuit 55 is configured or structured to communicate with the sensors 30 via the communications interface 54, receive information regarding various operating parameters of the system 10, and determine a difference between the sensed values of those operating parameters and associated expected values (or benchmarks) of those operating parameters. The resultant difference is referred to as a compression braking functionality value. The compression braking functionality values generally represent an amount that the compression braking system 11 is deviating from expected performance. These operating parameters are regarding operation of the compression braking system 11 and include, but are not limited to, an exhaust pressure (e.g., at or near the exhaust valve 16), charge pressure (e.g., at or near the intake valve 15), a charge flow rate, engine torque, and/or engine power output. An expected value for each of these parameters can be set as a function of engine speed for current operating conditions, such as a given ambient air density and engine type (e.g. number of cylinders, engine design characteristics such as swept cylinder volume, etc.). Then, by determining an actual value of a parameter at a particular engine speed, the quantity circuit 55 compares the actual value of the parameter and the expected value of the parameter and determines a difference (i.e., the compression braking functionality value) between the two. Exemplary charts illustrating the tracking of parameters performed by the quantity circuit 55 are shown in FIG. 3A, 4, and 5A, which are described below in more detail. Exemplary charts illustrating the determined compression braking functionality value for these same parameters are shown in FIGS. 3B, 4, and 5B, which are described below in more detail.
[0044] Accordingly and referring now to FIG. 3A, an exemplary chart 300 is shown of the quantity circuit 55 tracking two parameters: charge flow rate and charge pressure. An x-axis of chart 300 reflects a speed of the engine 12 and is given in units of revolutions per minute (RPM). An x-axis of chart 300 reflects a speed of the engine and is given in units of revolutions per minute (RPM), with values increasing from left to right. A left y-axis of chart 300 reflects a charge flow rate (e.g. as the charge enters the intake valve 15) and is given in units of kilograms per minute (Kg/min), with values increasing from bottom to top. A right y-axis of chart 300 reflects a charge pressure of air (e.g. as the charged air enters the intake valve 15) and is given in units of kilopascals (kPa (abs)), with values increasing from bottom to top. Line 310 plots a value of the charge flow rate when the compression braking system 11 is functioning properly, as a function of engine speed, and generally shows that charge flow rate increases as engine speed increases with a properly functioning compression braking system. Line 315 plots a value of the charge flow rate when the compression braking system 11 is not functioning properly, as a function of engine speed, and generally shows that charge flow rate similarly increases as engine speed increases with a malfunctioning compression braking system, but that the charge flow rate is generally at a lower level for the malfunctioning compression braking system. Dashed line 320 plots a value of the charge pressure when the compression braking system 11 is functioning properly, as a function of engine speed, and generally shows that charge pressure increases quickly as engine speed increases up to a point and then decreases gradually with a properly functioning compression braking system. Dashed line 325 plots a value of the charge pressure of air when the compression braking system 11 is not functioning properly, as a function of engine speed, and generally shows that charge pressure increases steadily as engine speed increases but that the charge pressure is generally at a lower level for the malfunctioning compression braking system. As shown, at every engine speed tracked on chart 300, the values of the charge flow rate and charge pressure are greater when the compression braking system 11 is functioning properly than when the compression braking system 11 is not functioning properly. Alternatively, if the engine 12 is a naturally aspirated engine (i.e., the engine 12 does not feature a turbocharger), the charge pressure will be substantially the same for a properly functioning compression braking system 11 and a malfunctioning compression braking system 11. In addition, the charge pressure will be substantially equal to an ambient pressure, due to the inherent functionality of a naturally aspirated engine.
[0045] In some embodiments, the lines 310 and 320 may illustrate a benchmark value for the charge flow rate and the charge pressure (respectively) that the quantity circuit utilizes to determine the compression braking functionality value associated with those parameters. In those embodiments, the benchmark values represent actually sensed values of the associated parameters in a system with a compression braking system functioning as intended (i.e., a “healthy” system). In order for an appropriate comparison to be done, the characteristics of the healthy system may be the same or generally the same as the tested system (e.g., same engine type, same number of cylinders utilized by the compression braking system, turbocharger system, aftertreatment system components, etc.). Thus, the healthy benchmark values are directly analogous for the system being tested/diagnosed. In operation, a variety of engine systems may be tested to acquire charts of healthy values thereby allowing a variety of engine systems to be diagnosed quickly.
[0046] While the lines 315 and 325, in this example, plot the charge flow rate and charge pressure (respectively) for when the compression braking system 11 is not properly functioning (unhealthy) (i.e. operating at 0% ability), the tracking performed by the quantity circuit 55 is not limited to those extremes, such that the quantity circuit may also track those parameters when the compression braking system 11 is functioning but functioning at a less-than-100% ability. As such, the lines 315 and 325 can be taken as illustrating sensed values (received from the sensors 30) of the system 10 to be diagnosed through comparison to the benchmark values of 310 and 320.
[0047] FIG. 3B shows an exemplary chart 350 of the quantity circuit 55 determining the compression braking functionality value for the same two parameters plotted in FIG. 3A. An x-axis of chart 350 reflects a speed of the engine and is given in units of revolutions per minute (RPM), with values increasing from left to right. A left y-axis of chart 350 reflects a charge flow rate of air (e.g., as the charged air enters the intake valve 15) and is given in units of kilograms per minute (Kg/min), with values increasing from bottom to top. A right y-axis of chart 350 reflects a charge pressure of air (e.g., as the charged air enters the intake valve 15) and is given in units of kilopascals (kPa (abs)), with values increasing from bottom to top. Line 360 plots a difference between lines 310 and 315 as a function of engine speed, and generally shows that the difference between lines 310 and 315 increases as engine speed increases up to a point and then decreases, but is never negative (i.e., the charge flow rate for a system with a properly function compression braking system is greater than the charge flow rate for a system with a malfunctioning compression braking system at every value of engine speed). Line 370 plots a difference between lines 320 and 325 as a function of engine speed, and generally shows that the difference between lines 320 and 325 increases as engine speed increases up to a point and then decreases, but is never negative (i.e., the charge pressure for a system with a properly function compression braking system is greater than the charge pressure for a system with a malfunctioning compression braking system at every value of engine speed). In those embodiments in which lines 310 and 320 illustrate benchmark values and lines 315 and 325 illustrate sensed values, lines 360 and 370 therefore illustrate compression braking functionality values for the associated parameters.
[0048] FIG. 4 shows an exemplary chart 400 of the quantity circuit 55 tracking a pressure of the exhaust gas (e.g., at the exhaust valve 16) and determining an associated compression braking functionality value. An x-axis of chart 400 reflects a speed of the engine and is given in units of revolutions per minute (RPM), with values increasing from left and right. A y-axis of chart 400 reflects a pressure of exhaust gas (e.g., as the exhaust gas exits the exhaust valve 16) and is given in units of kilopascals (kPa (abs)) with values increasing from bottom to top. Line 410 plots a value of the pressure of exhaust gas when the compression braking system 11 is functioning properly, as a function of engine 12 speed, and generally shows that exhaust pressure increases as engine speed increases for a properly function compression braking system. Line 420 plots a value of the pressure of exhaust gas (e.g., as the exhaust gas exits the exhaust valve 16) when the compression braking system 11 is not functioning properly, as a function of engine 12 speed, and generally shows that exhaust pressure similarly increases as engine speed increases with a malfunctioning compression braking system, but that the exhaust pressure is generally at a lower level for the malfunctioning compression braking system. Dashed line 430 plots a difference between lines 410 and 420 as a function of engine speed, and generally shows that the difference between lines 410 and 420 is increasing as engine speed increases and is almost entirely positive (i.e. the exhaust pressure for a system with a properly function compression braking system is greater than the exhaust pressure for a system with a malfunctioning compression braking system at every value of engine speed but relatively low values). Similarly to FIGS. 3A and 3B, in some embodiments, line 410 illustrates benchmark values for the exhaust pressure, line 420 illustrates sensed values for the exhaust pressure, and line 430 illustrates the compression braking functionality value for the exhaust pressure.
[0049] FIG. 5A shows an exemplary chart 500 of the quantity circuit 55 tracking two parameters: engine torque and engine power output. An x-axis of chart 500 reflects a speed of the engine and is given in units of revolutions per minute (RPM), with values increasing from left to right. A left y-axis of chart 500 reflects a torque of the engine and is given in units of Newton-meters (Nm), with values increasing from bottom to top. A right y-axis of chart 500 reflects a power output of the engine and is given in units of kilowatts (KW), with values increasing from bottom to top. Line 510 plots a sensed value of the torque of the engine when the compression braking system 11 is not functioning properly, as a function of engine speed, and generally shows that sensed torque increases steadily as engine speed increases. Line 520 plots an estimated value of the torque of the engine when the compression braking system 11 is not functioning properly, as a function of engine speed, and generally shows that the estimated torque increases steadily as engine speed increases for a malfunctioning compression braking system. This estimation is made based on sensed values of the engine speed, charge pressure (e.g., at the intake valve 15), exhaust pressure (e.g., at the exhaust valve 16), and a cam profile of the engine. Line 530 plots an estimated value of the torque of the engine when the compression braking system 11 is functioning properly, as a function of engine speed, and generally shows that estimated torque increases steadily as engine speed increases for a properly functioning compression braking system. This estimation is similarly made based on sensed values of the engine speed, charge pressure (e.g., at the intake valve), exhaust pressure (e.g., at the exhaust valve 16), and a cam profile of the engine 12.
[0050] Still referring to FIG. 5A, Line 515 plots a sensed value of the power output of the engine when the compression braking system 11 is not functioning properly, as a function of engine speed, and generally shows that sensed power output increases steadily as engine speed increases. Line 525 plots an estimated value of the power output of the engine when the compression braking system 11 is not functioning properly, as a function of engine speed, and generally shows that estimated power output increases steadily as engine speed increases for a malfunctioning compression braking system. This estimation is made based on sensed values of the engine speed, charge pressure (e.g., at the intake valve 15), exhaust pressure (e.g., at the exhaust valve 16), and a cam profile of the engine. Line 535 plots an estimated value of the power output of the engine when the compression braking system 11 is functioning properly as a function of engine speed, and generally shows that estimated power output increases steadily as engine speed increases for a properly functioning compression braking system. This estimation is similarly made based on sensed values of the engine speed, charge pressure (e.g., at the intake valve 15), exhaust pressure (e.g., at the exhaust valve 16), and a cam profile of the engine.
[0051] FIG 5B shows an exemplary chart of the quantity circuit 55 determining the compression braking functionality value for the same two parameters plotted in FIG. 5A. An x-axis of chart 550 reflects a speed of the engine and is given in units of revolutions per minute (RPM), with values increasing from left to right. A left y-axis of chart 550 reflects a torque of the engine and is given in units of Newton-meters (Nm), with values increasing from bottom to top. A right y-axis of chart 550 reflects a power output of the engine and is given in units of kilowatts (KW), with values increasing from bottom to top. Line 560 plots a difference between lines 530 and 520, such that, in some embodiments, line 560 plots the difference between a benchmark value for an estimated torque of the engine when the compression braking system 11 is properly functioning (i.e. line 530) and an estimated value (based on currently sensed values) of the torque of the engine when the compression braking system 11 is not properly functioning (i.e. line 520). Therefore, similarly to lines 360 and 370 of FIG. 3B, line 560 is, in these embodiments, plotting the compression braking functionality value for the estimated engine torque, and generally shows that the difference between lines 520 and 530 is increasing as engine speed increases and is entirely positive (i.e. the estimated torque for a system with a properly function compression braking system is greater than the estimated torque for a system with a malfunctioning compression braking system at every value of engine speed).. Line 570 plots a difference between lines 535 and 525, such that, in some embodiments, line 570 plots the difference between a benchmark value for an estimated power output of the engine when the compression braking system 11 is properly functioning (i.e. line 535) and an estimated value (based on currently sensed values) of the power output of the engine when the compression braking system 11 is not properly functioning (i.e. line 525). Thus, similarly to line 560, line 570 plots, in these embodiments, the compression braking functionality value for an estimated power output of the engine, and generally shows that the difference between lines 525 and 535 is increasing as engine speed increases and is entirely positive (i.e. the estimated power output for a system with a properly function compression braking system is greater than the estimated power output for a system with a malfunctioning compression braking system at every value of engine speed.
[0052] The threshold circuit 56 is structured or configured to receive the compression braking functionality values from the quantity circuit 55 and determine a health of the compression braking system 11 (i.e., whether the compression braking system 11 is properly functioning). The threshold circuit is structured or configured to retrieve a diagnostic threshold indicative of a “healthy” compression braking system, which may be based on an age of the compression braking system 11, the status of other components within the engine system 10, or operator preference.
[0053] In some embodiments, the threshold circuit 56 reacts to every instance of the compression braking functionality value exceeding or otherwise not aligning with a diagnostic threshold and raises an alert any time the diagnostic threshold is exceeded. In other embodiments, the threshold circuit 56 feeds the compression braking functionality values into an accumulated sum, i.e. ‘Cusum,’ function, which serves to absorb noise. The Cusum function totals the compression braking functionality values over a predefined period of time and triggers an alert if a sum total of the compression braking functionality values for the predefined period of time exceeds a predefined or preset threshold value for the sum of the compression braking functionality values for this period of time. This function operates like a bucket: if the bucket fills up with and exceeds the threshold value in a certain period of time, then the bucket overflows and an alert is triggered. By utilizing a Cusum function in these embodiments, the threshold circuit 56 ignores small compression braking functionality values which last for a short timeframe in order to avoid false faults and signal fatigue for the operators. For example, when the compression braking system 11 is first engaged (i.e., activated), there may be some lag in parameter response due to inertia from moving parts in the system 10, such as the turbine 23, that may not immediately react to the compression braking system 11 engagement.
[0054] In other embodiments, the threshold circuit 56 calculates an integral of the compression braking system values, examples of which are shown in FIGS. 6A and 6B. The utility of an integral calculation is similar to that of a Cusum function, in that the integral enables real-time monitoring of the compression brake functionality value over time. When the value of the integral reaches an established threshold, the threshold circuit 56 triggers an alert.
[0055] While in some embodiments, the threshold circuit 56 triggers an alert when the diagnostic threshold is exceeded, in other embodiments, the threshold circuit 56 triggers an alert when the compression braking functionality values do not align with the diagnostic threshold (e.g., the compression braking functionality value is within a range, such as 5%, of the diagnostic threshold). By triggering an alert in situations other than those in which the diagnostic threshold is fully exceeded, the threshold circuit 56 is adaptable and can be more sensitive to possible issues in the compression braking system 11. As such, the threshold circuit 56 can also trigger an alert in those situations in which the compression braking system 11 is functional but operating at less than 100%, such that the compression braking functionality values are approaching the diagnostic threshold but have not yet exceeded the diagnostic threshold, which may indicate a possible issue with the compression braking system but not a complete non-functional compression braking system Further, in some of these embodiments, the threshold circuit triggers a secondary alert that indicates that the compression braking functionality is within 5% of the diagnostic threshold but has not yet exceeded it, such that a user can anticipate an upcoming compression braking system 11 issue.
[0056] In some embodiments, the diagnostic threshold is determined based on engine type (e.g., number of cylinders, engine design characteristics such as swept cylinder volume, type of turbocharger, etc.) and/or based on those engine operating conditions that affect the ‘breathing’ capability of the engine (e.g., ambient air density, etc.).
[0057] Referring now to FIG. 6A, an exemplary chart 600 is shown of a system 10 featuring a compression braking system 11 that is not properly functioning. An x-axis of chart 600 reflects a time since which the compression braking system was engaged and is given in units of seconds (sec), with values increasing from left to right. A left y-axis of chart 600 reflects a charge pressure of the engine (e.g., at the intake valve 15) and is given in units of kiloPascals (kPa), with values increasing from bottom to top. A right y-axis of chart 600 reflects a value of the integral of the compression braking functionality value and is given in units kilopascal-seconds (kPa*sec), with values increasing from bottom to top. Line 610 plots a benchmark value over time for the charge pressure for this given engine and at this ambient air density, and shows, for this particular set of external operating conditions (e.g., road grade, tire pressure, external wind, etc.) and braking power exerted by the compression brake, that the benchmark charge pressure decreases over time after a properly functioning compression braking system is engaged. Line 620 plots a sensed value over time for the charge pressure, and shows, for this particular set of external operating conditions and braking power exerted by the compression brake, that the charge pressure remains flat over time after a malfunctioning compression braking system is engaged. Line 630 plots the integral of the difference (i.e. “Line 610” – “Line 620”) over time, and generally shows that the integral is continually increasing over time (i.e., the benchmark charge pressure in a system with a properly functioning compression braking system is greater than the charge pressure in a system with a malfunctioning compression braking system such that the difference is positive for the entire time following the compression brake system engagement). In some situations, such as when the vehicle is descending a particularly steep hill, engine 12 speed may still be increasing even with an engaged and properly functioning compression braking system 11. As such, in that situation, the charge pressure will increase over time, despite a properly functioning compression braking system 11. However, the charge pressure in that situation will still be greater for a properly functioning compression braking system 11 than for a malfunctioning compression braking system 11, meaning that the integral of the difference (e.g., Line 630) will still capture an indication of the functionality of the compression braking system 11.
[0058] Referring now to FIG. 6B, an exemplary chart 650 is shown of a system 10 featuring a compression braking system 11 that is properly functioning. The axes of chart 650 are the same units as those of the axes in chart 600. However, the x-axis and right y-axis of chart 650 are at a significantly smaller scale that that of chart 600 such that less time is passing from left to right and the line plotting the integral (line 635) is at less than 1/10th of the scale of line 630. Line 615 similarly plots a benchmark value over time for the charge pressure (e.g., at the intake valve 15) for this given engine and at this ambient air density, and shows, for this particular set of external operating conditions and brake power exerted by the compression brake, that the charge pressure decreases over time after a properly functioning compression braking system is engaged. Line 625 similarly plots a sensed value over time for the charge pressure at the intake valve 15, and generally shows that the charge pressure decreases over time after a properly functioning compression braking system is engaged. Line 635 similarly plots the integral of the difference (i.e. “Line 615” – “Line 625”) over time, and shows, for this particular set of external operating conditions and brake power exerted by the compression brake, that the integral is not consistently moving in one direction or the other (i.e., the difference between the benchmark values and the sensed values are not consistently different over time). As is clear through a comparison of lines 630 and 635, which plot the integrals of the compression brake functionality value for a non-functional and a functional compression braking system 11 respectively, monitoring the integral of these values over time is an effective way to identify non-functional compression braking systems because the integral monitoring a malfunctioning compression braking system (line 630) is continuously increasing while the integral monitoring a properly functioning compression braking system (line 635) is less consistent.
[0059] In response to a determination by the threshold circuit 56 that the diagnostic threshold has been exceeded (either at an instance, or as a result of Cusum/integration), the threshold circuit 56 raises an alert regarding the health of the compression braking system 11. In some embodiments, this alert is a flag raised that can be read by a technician during a service event. In other embodiments, the alert is a fault code that is, for example, accessible via a service diagnostic tool. In further embodiments, the alert is a lamp (e.g., indicator light) on a dashboard or other display area of the vehicle that is lit to signal the malfunction. In some embodiments, the alert may be transmitted to a remote attendant via a network. In this case, remote monitoring and review of the diagnostic is provided.
[0060] Referring now to FIG. 7, a method 700 for diagnosing a functionality of the compression braking system is shown, according to an example embodiment. Method 700 may be performed, at least in part, by the controller 26. Accordingly, reference may be made to the controller 26 and components of the system 10 to aid explanation of the method 700.
[0061] The method 700 begins at process 702. At process 704, the compression braking system 11 is activated. The controller 26 may provide a command to start compression braking thereby controlling the valves and other components of the engine to enable compression braking (e.g., causing the exhaust valve(s) to open during the compression stroke). This activation may be based on an explicit user input for compression braking (e.g., flipping a switch on a dashboard of the vehicle, pressing a button, pressing an icon on a touchscreen, etc.). This activation may be based on a programming in the controller 26.
[0062] At process 706, a value of a parameter indicative of compression braking system 11 performance is determined or acquired. Based on the parameter, the value may be sensed directly or may be estimated based on other sensed values. Possible parameters are shown at process 707. Following this determination, a benchmark value for the parameter is retrieved at process 708 based on factors given at process 709. Following this, the sensed and the benchmark values are compared at process 710. Then, at process 712, the results of the comparison are either fed into a cumulative summation (Cusum) function or calculated as an integral. If the results of the comparison are fed into a Cusum function, the results of the comparison over a pre-determined period of time are summed together. This result, either the cumulative sum or the integral, is then compared to a diagnostic threshold at decision 714, returning to process 706 if the results align with the threshold (714: YES) or triggering an alert at process 716 if the results do not align with the threshold (714: NO).
[0063] As utilized herein, the terms “approximately,” “about,” “substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.
[0064] It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples).
[0065] The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using one or more separate intervening members, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic. For example, circuit A communicably “coupled” to circuit B may signify that the circuit A communicates directly with circuit B (i.e., no intermediary) or communicates indirectly with circuit B (e.g., through one or more intermediaries).
[0066] While various circuits with particular functionality are shown in FIG. 2, it should be understood that the controller 26 may include any number of circuits for completing the functions described herein. For example, the activities and functionalities of the quantity circuit 55 and the threshold circuit 56 may be combined in multiple circuits or as a single circuit. Additional circuits with additional functionality may also be included. Further, the controller 26 may further control other activity beyond the scope of the present disclosure.
[0067] As mentioned above and in one configuration, the “circuits” may be implemented in machine-readable medium for execution by various types of processors, such as the processor 52 of FIG. 2. An identified circuit of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified circuit need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the circuit and achieve the stated purpose for the circuit. Indeed, a circuit of computer readable program code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within circuits, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.
[0068] While the term “processor” is briefly defined above, the term “processor” and “processing circuit” are meant to be broadly interpreted. In this regard and as mentioned above, the “processor” may be implemented as one or more general-purpose processors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), or other suitable electronic data processing components structured to execute instructions provided by memory. The one or more processors may take the form of a single core processor, multi-core processor (e.g., a dual core processor, triple core processor, quad core processor, etc.), microprocessor, etc. In some embodiments, the one or more processors may be external to the apparatus, for example the one or more processors may be a remote processor (e.g., a cloud based processor). Alternatively or additionally, the one or more processors may be internal and/or local to the apparatus. In this regard, a given circuit or components thereof may be disposed locally (e.g., as part of a local server, a local computing system, etc.) or remotely (e.g., as part of a remote server such as a cloud based server). To that end, a “circuit” as described herein may include components that are distributed across one or more locations.
[0069] Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.
[0070] Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.
,CLAIMS:WHAT IS CLAIMED IS:

1. A system, comprising:
a controller coupled to a compression braking system associated with an engine, the controller comprising at least one processor coupled to a memory storing instructions that, when executed by the at least one processor, cause the controller to perform operations comprising:
activate compression braking via the compression braking system associated with the engine;
determine a value of a parameter associated with operation of the compression braking system associated with the engine;
retrieve a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended;
compare the value of the parameter to the benchmark value of the parameter;
retrieve a diagnostic threshold indicative of a healthy compression braking system; and
responsive to determining that a result of the comparison does not align with the diagnostic threshold, provide an alert.

2. The system of claim 1, wherein the parameter associated with operation of the compression braking system is at least one of a pressure of exhaust gas exiting at least one cylinder of the engine, a pressure of charged air entering the at least one cylinder of the engine, a flow rate of charged air entering the at least one cylinder of the engine, an estimated torque of the engine, or an estimated power output of the engine.

3. The system of claim 1, wherein the benchmark value of the parameter is based on a speed of the engine.

4. The system of claim 1, wherein the diagnostic threshold is based on an age of the compression braking system.

5. The system of claim 1, wherein the determination that the result of the comparison does not align with the diagnostic threshold is based on a cumulative summation function that totals results of the comparison of the value to the benchmark value over a period of time.

6. The system of claim 1, wherein the instructions when executed by the at least one processor further cause the controller to perform operations comprising: responsive to determining that the result of the comparison is within a predefined amount of but does not exceed the diagnostic threshold, provide a secondary alert.

7. The system of claim 1, wherein the provided alert is at least one of a fault code or an illuminated lamp.

8. A method for diagnosing a compression braking system of an engine, the method comprising:
determining a value of a parameter associated with operation of a compression braking system of an engine;
retrieving a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended;
comparing the value of the parameter to the benchmark value of the parameter;
retrieving a diagnostic threshold indicative of a healthy compression braking system; and
responsive to determining that a result of the comparison does not align with the diagnostic threshold, providing an alert.

10. The method of claim 8, wherein the parameter associated with operation of the compression braking system is at least one of a pressure of exhaust gas exiting at least one cylinder of the engine, a pressure of charged air entering the at least one cylinder of the engine, a flow rate of charged air entering the at least one cylinder of the engine, an estimated torque of the engine, or an estimated power output of the engine.

11. The method of claim 8, wherein the benchmark value of the parameter is based on a speed of the engine.

12. The method of claim 8, wherein the diagnostic threshold is based on an age of the compression braking system.

13. The method of claim 8, wherein the determination that the result of the comparison does not align with the diagnostic threshold is based on a cumulative summation function that totals results of the comparison of the value to the benchmark value over a period of time.

14. The method of claim 8, further comprising, responsive to determining that the result of the comparison is within a predefined amount of but does not exceed the diagnostic threshold, providing a secondary alert.

15. The method of claim 8, wherein the provided alert is at least one of a fault code or an illuminated lamp.

16. A system, comprising:
a compression braking system associated with an engine; and
a controller coupled to the compression braking system, the controller configured to:
provide a command to activate compression braking via the compression braking system associated with the engine;
determine a value of a parameter associated with operation of the compression braking system of the engine;
retrieve a benchmark value of the parameter associated with a compression braking system for an engine that operates as intended;
compare the value of the parameter to the benchmark value of the parameter;
retrieve a diagnostic threshold indicative of a healthy compression braking system; and
responsive to determining that a result of the comparison does not align with the diagnostic threshold, provide an alert.
17. The system 16, wherein the diagnostic threshold is based on an age of the compression braking system.

18. The system of claim 16, wherein the determination that the result of the comparison does not align with the diagnostic threshold is based on a cumulative summation function that totals results of the comparison of the value to the benchmark value over a period of time.

19. The system of claim 16, responsive to determining that the result of the comparison is within a predefined amount of but does not exceed the diagnostic threshold, the controller is further configured to provide a secondary alert.

20. The system of claim 16, wherein the provided alert is at least one of a fault code or an illuminated lamp.

Dated 21st day of May 2021

Gopinath Arenur Shankararaj
IN/PA 1852
OF K&S PARTNERS