Fuel system including automatic adaptation to gaseous fuel changes

Abstract

A system includes an engine including a combustion cylinder; a fuel filling system includes a fuel rail configured to receive a gaseous fuel mixture from a fuel supply, a fuel injector in operative communication with the fuel rail and a combustion cylinder, and a pressure sensor system operatively coupled with the fuel rail and configured to provide an output indicative of a fuel pressure of the fuel rail. An electronic control system is in operable communication with the fueling system and controls an opening time of the plurality of fuel injectors to provide injection of the gaseous fuel mixture, determines fueling control parameters in response to an output of the pressure sensor system, a fueling control parameter is varied in response to a change in average molecular mass of the gaseous fuel mixture, and an injector operating parameter is adjusted in response to a change in the fueling control parameter.

Description

[0001] Cross-referencing This disclosure claims priority and benefit to U.S. Application No. 63 / 520,390, filed August 18, 2023, which is incorporated herein by reference. Technical Field

[0002] This application relates to fuel systems that automatically adapt to changes in gaseous fuel, fuel systems that identify gaseous fuel, and related devices, control logic, diagnostics, processes, systems, and technologies. Background Technology

[0003] Gaseous fuel filling systems for internal combustion engines and the control logic for such systems have many drawbacks, including those concerning accuracy, complexity, computational burden, dedicated hardware requirements, precision, reliability, and robustness, among others. There remains a significant demand for the unique devices, processes, systems, and techniques disclosed herein.

[0004] Disclosure of Example Implementations To clearly, concisely, and accurately describe the exemplary embodiments of this disclosure, the ways and processes of making and using these exemplary embodiments, and to enable the practice, making, and use of these exemplary embodiments, reference will now be made to certain exemplary embodiments, including those illustrated in the accompanying drawings, and these exemplary embodiments will be described using specific language. However, it should be understood that this is not intended to limit the scope of the invention, and that the invention includes and protects such changes, modifications, and further applications of the exemplary embodiments that will occur to those skilled in the art. Summary of the Invention

[0005] Some embodiments include unique control logic for gaseous fuel refueling systems. Further embodiments include unique devices, systems, and processes that include or embody such control logic. Further embodiments, forms, objects, features, advantages, aspects, and benefits will become apparent from the following description and drawings. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating certain aspects of an example engine system, including an example fuel filling system.

[0007] Figure 2 This is a schematic diagram illustrating certain aspects of an example fuel refueling system.

[0008] Figure 3 This is a schematic diagram illustrating certain aspects of an example fuel refueling system.

[0009] Figure 4 It is a flowchart illustrating certain aspects of the example process.

[0010] Figure 5 It is a graph illustrating certain aspects of determining the sound speed of an example gaseous fuel.

[0011] Figure 6 It is a graph illustrating certain aspects of determining the sound speed of an example gaseous fuel.

[0012] Figures 7 to 12 It is a graph illustrating certain aspects of determining the sound speed of an example gaseous fuel.

[0013] Figures 13 to 18 It is a graph illustrating certain aspects of determining the sound speed of an example gaseous fuel.

[0014] Figure 19 This is a schematic diagram illustrating certain aspects of the example control logic.

[0015] Figure 20 This is a schematic diagram illustrating certain aspects of the example control logic.

[0016] Figure 21 This is a schematic diagram illustrating certain aspects of the example control logic.

[0017] Figure 22 and Figure 23 It is a graph illustrating certain aspects of the example control logic. Detailed Implementation

[0018] refer to Figure 1 The illustration shows a system 11 including an engine 10 and a gaseous fuel filling system 9. The gaseous fuel filling system 9 is configured to supply gaseous fuels, such as natural gas, hydrogen, bio-derived gaseous fuels, mixed gas fuels, or other gaseous fuels or mixtures of gaseous fuels, for combustion in the engine 10. The engine 10 includes a combustion chamber 13 (also referred to as a cylinder) of a reciprocating in-cylinder piston engine, configured to generate mechanical power from the combustion of gaseous fuel supplied by fuel injectors 12. Fuel injectors 12 are in fluid communication with a corresponding combustion chamber 13 of the engine 10 and are configured to inject gaseous fuel supplied to their respective combustion chamber 13.

[0019] In the illustrated embodiment, fuel injector 12 is configured and provided as a port fuel injector, which is configured to inject fuel directly into a corresponding port of intake manifold 37 leading to a corresponding combustion chamber 13 of engine 10. Other embodiments may include other types and configurations of injectors, such as direct fuel injectors configured to inject fuel directly into the corresponding combustion chamber 13 of engine 10. In the illustrated embodiment, four fuel injectors 12 and four combustion chambers 13 are depicted; it should be understood that engine 10 may include fewer or more fuel injectors 12 and combustion chambers 13. System 11 may be provided in various forms, including as a prime mover system (or a component of a prime mover system) of a vehicle, a generator set, or other electrical systems configured to drive or supply power to various loads.

[0020] In the illustrated embodiment, the gaseous fuel refueling system 9 includes a gaseous fuel supply and injection system 17 and a gaseous fuel supply source 32. The gaseous fuel supply and injection system 17 includes one or more rails 30 and one or more sets of injectors 12, the injectors 12 being operatively coupled to and supplying gaseous fuel from a corresponding one of the one or more rails 30. The one or more rails 30 are further configured to receive pressurized fuel from the gaseous fuel supply source 32.

[0021] The gaseous fuel supply source 32 may include a high-pressure storage tank configured to store the supply of gaseous fuel under high pressure. In some embodiments, the gaseous fuel supply source 32 may include additional elements such as a compressor and mechanically or electronically controllable valves, the compressor being configured to compress gaseous fuel received from the fuel storage tank and supply the compressed gaseous fuel to one or more rails 30 and / or an accumulator and a filter, and the mechanically or electronically controllable valves being configured to control the supply of gaseous fuel to and from the accumulator and / or one or more rails 30.

[0022] It should be understood that the illustrated form of the gaseous fuel refueling system 9 is merely one example of a fuel refueling system according to this disclosure. In other embodiments, the gaseous fuel refueling system 9 may be configured and provided as another type of gaseous fuel refueling system, such as a gaseous hydrogen fuel refueling system. In other embodiments, the gaseous fuel refueling system 9 may be configured and provided in other forms.

[0023] System 11 also includes an electronic control system (ECS) 20 that communicates with engine 10 and is configured to control one or more aspects of engine 10, including controlling the injection of fuel into engine 10 via fuel injectors 12. Accordingly, ECS 20 may communicate with fuel injectors 12 and is configured to command each fuel injector 12 to open and close at predetermined times to inject fuel into engine 10 as needed. ECS 20 typically includes at least one electronic control unit (ECU) 22 configured to perform the operations of ECS 20, as further described herein, and in some embodiments, may include additional ECUs configured to perform the operations of ECS 20, as further described herein.

[0024] The ECS 20 can also be configured to control other parameters of the engine 10, which may include aspects of the engine 10 that can be controlled by actuators activated by the ECS 20. For example, the ECS 20 may communicate with actuators and sensors to receive and process sensor inputs and transmit actuator output signals. Actuators may include, but are not limited to, fuel injectors 12. Sensors may include any suitable devices for monitoring the operating parameters and functions of the system 11. For example, sensors may include one or more pressure sensors 16 and one or more temperature sensors 18. The one or more pressure sensors 16 communicate with one or more rails 30 and are configured to transmit measurements of the pressure of gaseous fuel in the one or more rails 30 (also referred to as fuel rail pressure or rail pressure) to the ECS 20. The one or more temperature sensors 18 communicate with one or more rails 30 and are configured to transmit measurements of the temperature of gaseous fuel in the one or more rails 30 (also referred to as fuel rail temperature or rail temperature) to the ECS 20. System 11 includes an intake manifold pressure (IMP) sensor 38 that communicates with and is configured to sense the pressure in the intake manifold 37.

[0025] As will be understood from the following description, the techniques described herein related to fuel injectors or fuel injection parameters can be implemented in ECS 20, which may include one or more controllers for different aspects of control system 11. In some embodiments, ECS 20 includes one or more electronic control units (ECUs), such as engine control units or engine control modules. ECS 20 may include digital circuitry, analog circuitry, or a hybrid combination of both. Furthermore, ECS 20 may be programmable, integrated state machines, or a hybrid combination thereof. ECS 20 may include one or more arithmetic logic units (ALUs), central processing units (CPUs), memories, limiters, regulators, filters, format converters, etc., which are not shown for clarity. In one form, ECS 20 is programmable, executing algorithms and processing data according to operating logic defined by programming instructions, such as software or firmware. Alternatively or additionally, the operating logic of ECS 20 may be defined at least in part by hardwired logic or other hardware.

[0026] In addition to the sensor types described herein, the system and method may encompass any other suitable sensor and its associated parameters. Accordingly, the sensor may include any suitable device for sensing any relevant physical parameters of engine system 11, including electrical, mechanical, and chemical parameters. As used herein, the term sensor may include any suitable hardware and / or software for directly or indirectly sensing or estimating any engine system parameters and / or various combinations of such parameters.

[0027] refer to Figure 2 Further details of an exemplary embodiment of the gaseous fuel filling system 9 are illustrated. In the illustrated example of the gaseous fuel filling system 9, the gaseous fuel supply source 32 is configured to supply pressurized gaseous fuel to a rail 30i, which in turn receives pressurized gaseous fuel from the gaseous fuel supply source 32, and is configured and operable to supply pressurized gaseous fuel to a plurality of injectors 12, which are configured to inject gaseous fuel into specific cylinder inlets of a plurality of cylinder inlets 14 associated with a plurality of cylinders 13.

[0028] In the illustrated example, the plurality of cylinders 13 include a first cylinder, a second cylinder, a third cylinder, a fourth cylinder, a fifth cylinder, and a sixth cylinder formed in the cylinder block of an inline six-cylinder engine 10i. The plurality of injectors 12 include injectors 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, and 6B. Injectors 1A and 1B are configured to supply gaseous fuel to a first intake port of the intake manifold 37 leading to the first combustion cylinder. Injectors 2A and 2B are configured to supply gaseous fuel to a second intake port of the intake manifold 37 leading to the second combustion cylinder. Injectors 3A and 3B are configured to supply gaseous fuel to a third intake port of the intake manifold 37 leading to the third combustion cylinder. Injectors 4A and 4B are configured to supply gaseous fuel to a fourth intake port of the intake manifold 37 leading to the fourth combustion cylinder. Injectors 5A and 5B are configured to supply gaseous fuel to the fifth intake port of the intake manifold 37 leading to the fifth combustion cylinder. Injectors 6A and 6B are configured to supply gaseous fuel to the sixth intake port of the intake manifold 37 leading to the sixth combustion cylinder.

[0029] exist Figure 2 In some embodiments, one or more pressure sensors 16 include pressure sensor 16a, and in some forms may also include pressure sensor 16b located at a separate location on rail 30i. Pressure sensors 16a, 16b communicate with rail 30i and are configured to transmit measurements of the pressure of gaseous fuel in rail 30i (also referred to as fuel rail pressure or rail pressure) to ECS 20.

[0030] exist Figure 2 In some embodiments, one or more temperature sensors include temperature sensor 18a. In some forms, one or more temperature sensors may also include additional or alternative temperature sensors located at a separate location on rail 30i or at other locations on the gaseous fuel filling system 9. Temperature sensor 18a communicates with rail 30i and is configured to transmit a measurement of the temperature of the gaseous fuel in rail 30i (also referred to as fuel rail temperature or rail temperature) to ECS 20.

[0031] It should be understood that Track 30i is one of the combinations Figure 1 The illustrated and described one or more rails 30 include one instance of a single rail. Other embodiments in which one or more rails 30 include multiple separate or separate rails are also contemplated. Similarly, while the illustrated example relates to an engine including six cylinders, other embodiments relate to other engines including more or fewer than six cylinders.

[0032] refer to Figure 3Further details of an exemplary embodiment of the gaseous fuel filling system 9' are illustrated. In the illustrated example of the gaseous fuel filling system 9', the gaseous fuel supply source 32 is configured to supply pressurized gaseous fuel to the front rail 30f and the rear rail 30r. The front rail 30f and the rear rail 30r are configured and provided as physically separate or separate gaseous fuel receiving structures, which can be provided in various forms, including, for example, as physically separate or separate tubular fuel rails or pipes or physically separate orifices formed in engine components such as intake manifolds or cylinder heads. The front rail 30f and the rear rail 30r are preferably supplied with pressurized gaseous fuel from the gaseous fuel supply source 32 at separate and different locations to effectively provide a degree of isolation between their respective pressures.

[0033] The front rail 30f is configured and operable to supply pressurized gaseous fuel to a plurality of front injectors 12f, which are configured to inject gaseous fuel into specific front cylinder intakes among a plurality of front cylinder intakes 14f associated with a plurality of first cylinders 13f. In the illustrated example, the first plurality of cylinders 13f includes a first cylinder, a second cylinder, and a third cylinder formed in the block of an inline six-cylinder engine 10i'. In the illustrated example, the plurality of front injectors 12f includes injectors 1A, 1B, 2A, 2B, 3A, and 3B. Injectors 1A and 1B are configured to supply gaseous fuel to a first intake port of the intake manifold 37 leading to a first combustion cylinder. Injectors 2A and 2B are configured to supply gaseous fuel to a second intake port of the intake manifold 37 leading to a second combustion cylinder. Injectors 3A and 3B are configured to supply gaseous fuel to the third intake port of the intake manifold 37 leading to the third combustion cylinder.

[0034] The rear rail 30r is configured and operable to supply pressurized gaseous fuel to a plurality of rear injectors 12r, which are configured to inject gaseous fuel into specific rear cylinder intakes among a plurality of rear cylinder intakes 14r associated with a plurality of second plurality of cylinders 13r. In the illustrated example, the second plurality of cylinders 13r includes a fourth, fifth, and sixth cylinder formed in the block of an inline six-cylinder engine 10i'. In the illustrated example, the rear plurality of injectors 12r includes injectors 4A, 4B, 5A, 5B, 6A, and 6B. Injectors 4A and 4B are configured to supply gaseous fuel to a fourth intake port of the intake manifold 37 leading to a fourth combustion cylinder. Injectors 5A and 5B are configured to supply gaseous fuel to a fifth intake port of the intake manifold 37 leading to a fifth combustion cylinder. Injectors 6A and 6B are configured to supply gaseous fuel to the sixth intake port of the intake manifold 37 leading to the sixth combustion cylinder.

[0035] In the illustrated example, the plurality of cylinders 13 include a first cylinder, a second cylinder, a third cylinder, a fourth cylinder, a fifth cylinder, and a sixth cylinder formed in the cylinder block of an inline six-cylinder engine 10i. The plurality of injectors 12 include injectors 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, and 6B. Injectors 1A and 1B are configured to supply gaseous fuel to a first intake port of the intake manifold 37 leading to the first combustion cylinder. Injectors 2A and 2B are configured to supply gaseous fuel to a second intake port of the intake manifold 37 leading to the second combustion cylinder. Injectors 3A and 3B are configured to supply gaseous fuel to a third intake port of the intake manifold 37 leading to the third combustion cylinder. Injectors 4A and 4B are configured to supply gaseous fuel to a fourth intake port of the intake manifold 37 leading to the fourth combustion cylinder. Injectors 5A and 5B are configured to supply gaseous fuel to the fifth intake port of the intake manifold 37 leading to the fifth combustion cylinder. Injectors 6A and 6B are configured to supply gaseous fuel to the sixth intake port of the intake manifold 37 leading to the sixth combustion cylinder.

[0036] exist Figure 3 In some embodiments, one or more pressure sensors 16 include pressure sensor 16f and pressure sensor 16r. Pressure sensor 16f communicates with the front rail 30f and is configured to transmit a measurement of the pressure of the gaseous fuel in the front rail 30f (also referred to as fuel rail pressure or rail pressure) to the ECS 20. Pressure sensor 16r communicates with the front rail 30r and is configured to transmit a measurement of the pressure of the gaseous fuel in the front rail 30r (also referred to as fuel rail pressure or rail pressure) to the ECS 20. It should be understood that in some forms, one or more pressure sensors 16 may include one or more additional pressure sensors that communicate with the front rail 30f or the rear rail 30r and are configured to transmit a measurement of the pressure of the gaseous fuel in the front rail 30f or the rear rail 30r.

[0037] exist Figure 2 In some embodiments, one or more temperature sensors include temperature sensors 18f and 18r. In some forms, the one or more temperature sensors may also include additional or alternative temperature sensors located at separate locations on rails 30f and 30r or at other locations on the gaseous fuel filling system 9. Temperature sensor 18f communicates with rail 30f and is configured to transmit a measurement of the temperature of the gaseous fuel in rail 30f (also referred to as fuel rail temperature or rail temperature) to ECS 20. Temperature sensor 18r communicates with rail 30r and is configured to transmit a measurement of the temperature of the gaseous fuel in rail 30r (also referred to as fuel rail temperature or rail temperature) to ECS 20.

[0038] It should be understood that the front rail 30f and the rear rail 30r are a combination of these. Figure 1The illustrated and described one or more rails 30 include an example of a first rail and a second rail separate or separate from the first rail. Other embodiments are also contemplated, wherein one or more rails 30 include a first rail and a second rail separate or separate from the first rail. Such embodiments include, for example, systems comprising, a relative arrangement and positioning of multiple fuel rails serving a group of inline cylinders in addition to front and rear axles, systems in which one or more fuel rails 30 include three or more fuel rails, and / or systems in which one or more fuel rails 30 include two or more fuel rails configured to supply gaseous fuel to the same group or group of cylinders. Similarly, while the illustrated example relates to an engine comprising six cylinders, other embodiments relate to other engines comprising more or fewer than six cylinders.

[0039] This disclosure envisions numerous embodiments, including apparatuses, processes, and systems, in which the molecular mass (sometimes referred to as average molecular mass), gas flow rate, injection quantity, and energy content of the gaseous fuel mixture can be determined using real-time on-engine measurements of the speed of sound of the operating gaseous fuel mixture. Some such embodiments may determine these parameters entirely or in part based on relationships according to one or more of equations (1), (2), (3), (4), (5), and (6): (1) (2) (3) (4) (5) (6) In equations (1), (2), (3), (4), (5), and (6), if applicable, c = speed of sound, γ = specific heat ratio of the gaseous mixture, R = universal gas constant, and T = absolute temperature. =The average molecular mass of the gaseous mixture, =Gas blockage flow rate, =Effective emission coefficient of the injector, =Effective flow area of ​​the injector =The average supply pressure to the injector during the injection event, and =The average downstream pressure to the injector during the injection event. It should be understood that equation (4) considers and simulates blocked flow conditions, while equation (6) considers and simulates non-blocked conditions with a Mach number less than 1. Furthermore, equation (5) can be used to test blocked and non-blocked system conditions. If the state of the fuel filling system makes equation (5) true, the flow is blocked, and equation (4) is used to calculate the mass flow rate. If the state makes equation (5) false, the flow is not blocked, and equation (6) is used to calculate the mass flow rate.

[0040] refer to Figure 4 The illustration depicts an example process 100 for operating an electronic control system (e.g., ECS 20 or another electronic control system) that is operatively in communication with a fuel dispensing system (e.g., gaseous fuel dispensing system 9 or another fuel dispensing system). Process 100 may be implemented in and executed by one or more components of an electronic control system, such as one or more electronic control units (e.g., ECU 22 and / or other electronic control units), and / or executed by other electronic control system components.

[0041] Process 100 begins with initiation operation 102 and proceeds to operation 104, which operates the engine system. In some modes, operation 104 can operate the engine system during a mission, eliminating the need for special or dedicated operating modes, although some modes may utilize special or dedicated operating modes, such as test or calibration modes. Operation 104 can control various aspects of the engine system's operation, including, for example, controlling the opening timing of multiple fuel injectors to provide the injection of a gaseous fuel mixture for engine combustion, controlling rail pressure, and controlling injection timing.

[0042] From operation 104, process 100 proceeds to operation 106, which determines engine control parameters in response to the output of the fuel pressure sensor system. It should be understood that engine control parameters may include any or more of a plurality of parameters, such as, for example, fuel quantity, injection timing, number of injection events, fuel system pressure, ignition timing, intake manifold pressure, and airflow, to name just a few. Additionally, one or more engine control parameters may be used to determine one or more injector operating parameters directly acting on the fuel injectors, such as injector opening time (e.g., the total time for which the injectors are commanded to open for a given injection event, and / or the initial time at which the injectors are first commanded to open).

[0043] It should also be understood that parameters such as fuel quantity and injection timing on one hand and injector opening time on the other hand can be related. However, it is distinguishable that fuel quantity and injection timing include parameters stored in the memory of the electronic control system, while injector opening time includes an operating state that can be observed externally without direct access to or understanding of the parameters stored in the memory of the electronic control system, for example, by measuring signals (such as voltage or current) provided to the fuel injector by the electronic control system. In some aspects and instances, engine control parameters and injector operating parameters can be directly related or substantially the same, for example in control logic where injection timing is used to directly determine the injector opening time. In some aspects and instances, engine control parameters and injector operating parameters can be indirectly related or influenced by multiple or additional factors, for example in control structures where the total injector opening time is determined in response to fuel quantity, fuel system pressure, and potentially other control parameters for a given injection event.

[0044] Operation 106 may utilize a variety of techniques related to determining engine control parameters in response to the output of the fuel pressure sensor system. In some embodiments, operation 106 may determine the velocity of sound parameters of the gaseous fuel mixture in response to the output of the pressure sensor system, and may determine gaseous fuel characteristics indicating the molecular weight of the fuel in response to the velocity of sound parameters. In some embodiments, operation 106 may directly determine the gaseous fuel characteristics indicating the molecular weight without having to determine or calculate the velocity of sound parameters.

[0045] Operation 106 may utilize various techniques to determine the sound velocity parameters of the gaseous fuel mixture in response to the output of the pressure sensor system. Such techniques may include, for example, time-difference techniques, natural frequency techniques, Fourier transform techniques, oscillation decay techniques, and other techniques disclosed and revealed herein. Operation 106 may also utilize various techniques to determine gaseous fuel characteristics indicating the molecular weight of the fuel. Such techniques may include, for example, the sound velocity calculation techniques disclosed herein, the molecular therapy determination techniques disclosed herein, and / or calculations based on any of equations (1), (2), (3), (4), (5), and (6). It should be understood that operation 106 may be repeated for purposes such as obtaining increased confidence in the accuracy and precision of engine control parameter estimates and obtaining estimates of engine control parameters under different pressure or temperature conditions.

[0046] From operation 106, process 100 proceeds to operation 108, in which the engine system receives and operates using a modified gaseous fuel mixture. The engine system may receive a modified gaseous fuel mixture under a variety of conditions, including, for example, refueling events, changes in pipeline gas composition, changes in wellhead gas composition, mixing of multiple gaseous fuel sources, or changes in such mixing, among others. It should be understood that changes in the gaseous fuel mixture may involve changes in the average molecular mass of the gaseous fuel mixture due to changes in the molecular composition of the gaseous fuel supplied to the engine system. It should also be understood that changes in the gaseous fuel mixture may not be known in advance by operation 108, process 100, or the means or systems therein that realize and execute them.

[0047] From operation 108, process 100 proceeds to operation 110, which changes engine control parameters in response to a change in the average molecular weight of the gaseous fuel mixture. Operation 110 may utilize various techniques associated with changing engine control parameters in response to a change in the average molecular weight of the gaseous fuel mixture, including, for example, techniques disclosed and referenced in conjunction with operation 106. In some embodiments, operation 110 may determine a new value for the velocity of sound parameter of the fuel in response to the output of a pressure sensor system, and may determine a new value for a gaseous fuel characteristic indicating the molecular weight of the fuel in response to the new value of the velocity of sound parameter.

[0048] From operation 110, process 100 progresses to operation 112, which adjusts injector operating parameters in response to changes in average molecular mass to effectively mitigate variations in engine output. Operation 112 can adjust one or more injector operating parameters, and such adjustments can be made using a variety of techniques, including, for example, combining... Figure 20 The technologies disclosed herein are those disclosed elsewhere in this document.

[0049] From operation 112, process 100 proceeds to operation 114. At operation 114, the process ends, repeats, or returns to a previous operation, such as operation 104.

[0050] This disclosure envisions various techniques for determining the speed of sound of a gaseous mixture on an engine under current operating pressure and temperature conditions. Some embodiments may utilize time-difference techniques to determine the speed of sound parameters of the gaseous fuel. Such embodiments may measure the difference in pressure sensor response time after one or more injection events and compare the difference in response time with the distance between the operating injector and the pressure sensor. Like many other techniques disclosed herein, time-difference techniques can discreetly, on the engine, and in real time determine the speed of sound of an operating gaseous fuel mixture.

[0051] In some differential time techniques, the electronic control system can receive a first output corresponding to an injection event from a first pressure sensor of a pressure sensor system. The first pressure sensor can be configured to sense fuel pressure associated with a first position on the fuel rail. The electronic control system can receive a second output corresponding to the same injection event from a second pressure sensor of the pressure sensor system. The second pressure sensor can be configured to sense fuel pressure associated with a second position on the fuel rail spaced apart from the first position. In combination... Figure 2 In the illustrated and described example embodiments, the first pressure sensor may be pressure sensor 16a of the gaseous fuel filling system 9, and the second pressure sensor may be pressure sensor 16b of the gaseous fuel filling system 9, and the injector may be either of the injectors. In combination Figure 3 In the illustrated and described example embodiments, the first pressure sensor may be pressure sensor 16f of the gaseous fuel filling system 9', and the second pressure sensor may be pressure sensor 16r of the gaseous fuel filling system 9'.

[0052] The electronic control system can determine the sound speed parameter in response to the difference between the first and second outputs (difference time) and the inverse relationship between the sound speed of the gaseous fuel and the difference time. Figure 5 The figure illustrates an example of such an inverse relationship between the speed of sound of gaseous fuel on the vertical axis and the time difference on the horizontal axis. Figure 5 The inverse relationship depicted is related to a specific gaseous fuel temperature and supply pressure. It should be understood that the slope of the inverse relationship between the speed of sound of the gaseous fuel and the time difference may change as the gaseous fuel temperature and supply pressure vary. Multiple inverse relationships under various gaseous fuel temperatures and supply pressures can be established and stored as one or more equations, mappings, tables, or other data structures, which electronic control systems can utilize to determine the speed of sound parameters of the gaseous fuel in response to the time difference, gaseous fuel pressure, and gaseous fuel temperature.

[0053] In some differential time techniques, the electronic control system can receive a first output from a pressure sensor of a pressure sensor system corresponding to a first injection event performed by a first injector of a fuel filling system, the first injector being spaced a first distance from the pressure sensor. The electronic control system can also receive a second output from the pressure sensor corresponding to a second injection event performed by a second injector of the fuel filling system, the second injector being spaced a second distance from the pressure sensor, different from the first distance. The electronic control system can determine the speed of sound parameters in response to the difference between the first and second outputs, and the distance difference between the first pressure sensor and the injector performing the first injection event, and the distance difference between the second pressure sensor and the injector performing the first injection event.

[0054] It should be understood that the differential time velocity determination technique according to this disclosure can take into account potential differences in the response time of pressure sensors in various ways. One example method involves performing injection with injectors 2A and 2B and measuring the differential time of the resulting pressure disturbance observed at a rear pressure sensor 16r, which is further away from the operating injectors 2A and 2B at a known distance along the flow path compared to a front pressure sensor 16f, which is closer to the operating injectors 2A and 2B at a known distance along the flow path. The method then involves performing injection with injectors 5A and 5B and measuring the differential time of the resulting pressure disturbance observed at a front pressure sensor 16f, which is further away from the operating injectors 5A and 5B at a known distance along the flow path compared to a rear pressure sensor 16r, which is closer to the operating injectors 5A and 5B at a known distance along the flow path. The average of the time difference between these two events provides a method for the control system to mitigate the impact of any pressure sensor's response time difference.

[0055] Some embodiments may utilize intrinsic frequency techniques to determine the speed of sound parameters of gaseous fuels. Like many other techniques disclosed herein, intrinsic frequency techniques can discreetly, on-engine, and in real time determine the speed of sound of an operating gaseous fuel mixture.

[0056] Example natural frequency techniques can determine one or more natural frequencies of the pressure sensor outputs of a pressure sensor system after an injection event, and can determine sound velocity parameters in response to one or more natural frequencies. For example, when the pressure in the rail is relatively stable under near-quasi-static conditions, such as when the engine is in motion, an electronic control system can command injection events from one or more injectors in a set of injectors associated with engine cylinders. The free response of the pressure in one or both of the rails can be measured by one or more pressure sensors after a single injection command. Then, using one of many possible methods, including Discrete Fourier Transform (DFT), sine curve fitting-based estimation, or any other similar method, frequency analysis is performed to calculate the free response after a single injection event from the measured pressure signal.

[0057] Figure 6 The diagram illustrates the use of Figure 3 The system's natural frequency technique is an example, where injector 2A is commanded to inject. For different gaseous fuel mixtures, the calculated natural frequency of the system, measured at the front rail pressure sensor, is calculated, and... Figure 8 The x-axis is shown in the graph. The y-axis of the graph shows the speed of sound for different gaseous fuel mixtures at different times and states during the injection event. Figure 6As shown in the graph, there is an approximately linear relationship between the natural frequency and the speed of sound, which can be used to calculate the speed of sound. Similar methods can be used for, for example... Figure 2 The system configuration shown.

[0058] Some embodiments may utilize peak amplitude discrete Fourier transform (DFT) techniques to determine the sound velocity parameters of gaseous fuels. Like many other techniques disclosed herein, peak amplitude DFT techniques can discreetly, on-engine, and in real time determine the sound velocity of an operating gaseous fuel mixture.

[0059] Figures 7 to 12 The illustration shows some aspects of the peak amplitude peak oscillation (DFT) technique, which utilizes the DFT peak amplitude of the rail pressure at the harmonics of the 1.5 engine ignition frequency. For Figure 7 , Figure 8 and Figure 9 The curves shown in the figure are for systems with identical configurations, engine operating conditions, and fuel pressure and temperature; however, as can be observed by comparing these curves, the DFT amplitude at the 1.5 engine ignition frequency harmonics varies with different gaseous fuel mixtures. The properties of the fuel mixture similarly affect all DFT harmonics.

[0060] One peak amplitude DFT technique that can be used to identify operating fuel is to compare engine operating speeds at which the maximum DFT amplitude is observed at the 1.5 engine ignition frequency harmonic. For this example, in Figure 10 The diagram shows the maximum calculated DFT amplitude at the 1.5 engine ignition frequency harmonics as a function of engine speed for different gas mixtures. (Example...) Figure 11 As shown in the graph, for example embodiments of different gaseous mixtures, the engine speed at which the maximum calculated DFT amplitude is at the 1.5 engine ignition frequency harmonic is shown to be related to the speed of sound of the gaseous mixture under gas operating conditions, as defined by equation (1). Figure 12 As shown, the control structure of the engine and fuel system can use DFT results to estimate the speed of sound of the gaseous mixture. This speed of sound can then be combined with equation (2) to estimate the molecular mass of the gaseous mixture.

[0061] Peak amplitude DFT techniques, such as those described above, can be implemented in an electronic control system configured to determine the speed of sound parameters by determining the maximum amplitude of the Fourier transform of the pressure sensor system's output, and to determine the speed of sound parameters in response to the maximum amplitude. The Fourier transform of the pressure sensor system's output includes the Fourier transform at 1.5 harmonics of the engine ignition frequency or other suitable multiples of the engine ignition frequency.

[0062] Some embodiments can utilize damped oscillation techniques to determine the speed of sound parameters of gaseous fuels. Like many other techniques disclosed herein, damped oscillation techniques can discreetly, on-engine, and in real time determine the speed of sound of an operating gaseous fuel mixture.

[0063] Figure 13 , Figure 14 and Figure 15 The illustration shows an example of supply pressure measurement. Figure 13 The diagram illustrates the supply pressure measurement when the fuel system is operating with 100% methane. Figure 14 The diagram illustrates the supply pressure measurement when the fuel system operates with a gaseous mixture of 90% methane and 10% hydrogen by mass. Figure 15 The diagram illustrates the supply pressure measurement when the fuel system operates with a gaseous mixture of 80% methane and 20% hydrogen by mass. Figure 13 , Figure 14 and Figure 15 Each figure shows the injection rate profile, injection quantity, pressure at the supply pressure sensor associated with the injector operating in a six-cylinder engine with cylinders 1, 2, and 3, and the filtered supply pressure. For a representative example, all three figures show engine operating conditions at 800 rpm and a single injection quantity of approximately 40 mg. All three figures show a gaseous fuel supply temperature of 40°C before the injector.

[0064] The speed of sound (c) of the gaseous mixture can be determined according to equation (1). Figure 16 It shows that for Figure 13 , Figure 14 and Figure 15 The example data shown illustrates the relationship between the sound velocity of the gaseous mixture and the time period associated with the oscillation of the filtered supply pressure after the ejection event. (As in...) Figure 16 As can be seen, there is a significant correlation between the speed of sound and the oscillation time period under the measurement conditions. The data also show an inverse relationship between the oscillation time period and the speed of sound. Therefore, data from measurements of the oscillation time period at engine speed, injection rate, and temperature can be used to determine the speed of sound, which can then be used to estimate the composition and properties of gaseous fuels.

[0065] Data from multiple measurements at different fuel supply temperatures, fuel supply pressures, injection rates, and engine speeds can improve measurement accuracy and estimate fuel properties and component percentages. The average molar mass of the gaseous mixture (…) The mole fraction of the components can be determined from equation (7). and their molar mass calculate: (7) Average molar mass of gaseous mixture Alternatively, the mass fraction of the component can be determined from equation (8). and their molar mass calculate: (8) Figure 17 Example molar masses of several gases and gaseous mixtures are shown. Figure 17 As shown, even for gaseous blends identified as natural gas, there can be significant differences in molar mass. Figure 17 The adiabatic ratio, also known as the specific heat ratio of different gases and gas mixtures at a temperature of 40°C and an absolute pressure of 6 bar, is also shown.

[0066] Figure 18 An example is shown of how the adiabatic ratio (also known as the specific heat ratio of the example gas 100% methane) varies with fuel temperature and pressure. Using data and information measured during engine operation at different supply pressures and temperatures, the molecular mass and adiabatic ratio as a function of pressure and temperature can be estimated. This information can then be used to estimate the relative percentage of components in the operating gas. The relationship for the mass flow rate under blocked flow conditions of the gaseous injector is given in equation (9): (9) In equation (9), Cd is the effective emission factor, and A T The effective flow area at temperature, s is the average supply pressure during the injection event, c is the speed of sound, and γ is the adiabatic ratio. As can be seen from equation (9), the mass flow rate is inversely proportional to the speed of sound. Therefore, the speed of sound estimate based on the oscillation period of the supply pressure after the injection event can be readily used to compensate for changes in the mass flow rate as a function of the speed of sound of the gas in the current operating state of the fuel system in an operating engine.

[0067] Other methods can be used to estimate the speed of sound and gas properties. One alternative is to measure the oscillation period after a single isolated injection event during a period when the engine does not otherwise command the fuel for combustion, such as during engine maneuvering. Another additional method is to use the change in the magnitude of the amplitude of the supply pressure oscillation after the injection event. As shown in equation (9), a lower speed of sound results in a higher mass flow rate.

[0068] According to some damped oscillation techniques, an electronic control system can be configured to determine the speed of sound parameter by: determining the damped oscillation period of the output of the pressure sensor of the pressure sensor system after an injection event, and determining the speed of sound parameter in response to the damped oscillation period. In such embodiments, the electronic control system may perform at least one of the following: determining the damped oscillation period of a single injection event and using the inverse relationship between the speed of sound parameter and the damped oscillation period to determine the speed of sound parameter, and / or determining the damped oscillation period during transient engine operation.

[0069] refer to Figure 19 Example control logic 200 exists, which can be implemented and executed by an electronic control system (e.g., ECS 20 or another electronic control system) operatively communicating with a fuel dispensing system (e.g., gaseous fuel dispensing system 9 or another fuel dispensing system). Control logic 200 can be implemented and executed in one or more components of the electronic control system (such as one or more electronic control units (e.g., ECU 22 and / or other electronic control units)) and by one or more components of the electronic control system and / or by other electronic control system components. Control logic 200 is an example of control logic in which gaseous fuel pressure and temperature measurements are used to estimate the characteristics of the gaseous fuel and fuel based on the time period associated with the measurement and the oscillation of the supply pressure after the injection event.

[0070] Control logic 200 can be executed during the operation of the engine system in a mission, so that no special or dedicated operating mode is required, although some modes may utilize special or dedicated operating modes, such as test mode or calibration mode.

[0071] The manipulator 202 uses one or more pressure sensors (such as combined) Figures 1 to 3 One or more of the pressure sensors illustrated and described obtain one or more measurements of the gaseous fuel supply pressure (also referred to herein as "supply pressure"). Operator 202 optionally provides one or more pressure measurements to operator 204, which filters the supply pressure. Alternatively, operator 202 may provide one or more pressure measurements to operators 205 and 206. For systems with more than one pressure sensor, a method such as averaging two response pressures can be used to correct the pressure signal for the offset deviation of each pressure sensor.

[0072] Operator 204 filters the supply pressure. Operator 204 may utilize filtering techniques such as moving average filters to improve the accuracy and precision of the measurement and to improve the signal-to-noise ratio of the measurement. Operator 204 provides one or more filtered pressure measurements to operators 205 and 206.

[0073] Operator 205 calculates the average supply pressure associated with one or more filtered pressure measurements received from operator 204, or alternatively, the average supply pressure associated with one or more pressure measurements received from operator 202.

[0074] The actuator 206 calculates a sound velocity parameter in response to one or more pressure measurements. It should be understood that the sound velocity parameter may include a sound velocity value or a value related to or determined from the sound velocity value. The actuator 206 may utilize any techniques disclosed herein when calculating the sound velocity parameter based on the relationship between pressure and sound velocity, including, for example, time-difference techniques, natural frequency techniques, damped oscillation techniques, and DFT maximum amplitude techniques. In some embodiments, the actuator 206 may calculate the oscillation period based on the peak-to-peak duration or time of the oscillating pressure waveform. In some embodiments, the actuator 206 may calculate the difference response time of two pressure sensors to the same injection event. In some embodiments, the actuator 206 may calculate the free response to one or more natural frequencies. In some embodiments, the actuator 206 may calculate the maximum DFT amplitude.

[0075] Operator 207 uses one or more temperature sensors (such as combined) Figures 1 to 3 One or more of the temperature sensors illustrated and described obtain one or more measurements of the gaseous fuel supply temperature (also referred to herein as the “supply temperature”).

[0076] The actuator 208 calculates the speed of sound of the fuel for measurement in response to the speed of sound parameters determined by the actuator 206. Figure 16 The diagram illustrates the... Figure 13 , Figure 14 , Figure 15 The example data shown illustrates the relationship between the velocity of sound in the gaseous mixture and the time period associated with oscillations in the filtered supply pressure following an ejection event. (As in...) Figure 8 As can be seen, there is a correlation between the speed of sound and the oscillation time period under the measurement conditions; that is, there is an inverse relationship between the oscillation time period and the speed of sound. Therefore, data from measurements of the oscillation time period at engine speed, injection quantity, and temperature can be used to determine the speed of sound, which can then be used to estimate the composition and properties of gaseous fuels.

[0077] The operator 210 updates one or more models, equations, mappings, tables and / or other data structures or control logic used to express the speed of sound of gaseous fuel as a function of gaseous fuel temperature and gaseous fuel pressure.

[0078] The actuator 211 estimates the effective molecular mass of the gaseous fuel. The actuator 211 can calculate the effective molecular mass of the gaseous mixture, for example, according to equation (2) or an equivalent or similar equation. It is approximated as the ratio of the adiabatic ratio (γ), the universal gas constant (R), and the absolute temperature (T) divided by the speed of sound ( The square of ).

[0079] The operator 212 estimates the effective adiabatic ratio of gaseous fuel at different pressures and temperatures, for example, based on one of the equations (1) to (6) solved for the adiabatic ratio γ (γ).

[0080] The actuator 214 sets fuel system and engine control commands, such as injection quality and injection timing, and other affected algorithms or controls, based on the effective molecular mass of the fuel determined by the actuator 211 and the effective adiabatic ratio of the gaseous fuel at different pressures and temperatures determined by the actuator 212.

[0081] Operator 216 may optionally attach the engine’s gaseous properties history to a data log and storage device, or otherwise store such information.

[0082] Combination Figure 20 The illustration shows example control logic 900, which may be implemented in and operated by one or more components of an electronic control system, such as ECS 20 or another electronic control system configured to operatively communicate with a fuel filling system. In some forms, at least a portion of control logic 900 may be implemented in one or more electronic control units (such as ECU 22 or additional or alternative electronic control units) of the electronic control system.

[0083] Control logic 900 includes injector control logic 910, which is configured to determine and output at least one injector control signal 919 in response to one or more inputs to control the operation of injector 12i. In the illustrated example, injector control logic 910 is configured to determine and output an injector command for a particular individual injector 12i. Control logic 900 may include additional instances of injector control logic that are the same as or similar to injector control logic 910, which are configured to determine and output injector commands for other particular individual injectors.

[0084] In the illustrated example, injector control logic 910 is configured to receive multiple inputs, including a fuel filler command 902, engine speed 903, and intake manifold pressure (IMP) 904, rail pressure 906, and rail temperature 908. In other embodiments, injector control logic 910 may be configured to receive additional or alternative inputs.

[0085] The fuel filling command 902 may include fuel filling amount (Q) and fuel filling pressure (P). The fuel filling command 902 may be determined and provided to the injector control logic 910 in response to operator inputs such as accelerator pedal position or to automated operation of an electronic control system such as an adaptive cruise control system. Engine speed 903 may be provided by an engine speed sensor. Engine speed 903 may be provided to the injector control logic 910 via a dedicated connection or via one or more communication networks.

[0086] IMP 904 can be provided by pressure sensor 38, which is operatively in communication with and configured to sense the pressure of the intake manifold 37. IMP 904 can be provided to injector control logic 910 via a dedicated connection or via one or more communication networks. IMP 904 can be used as the intake manifold pressure described above in conjunction with control logic 200, or it can be used to determine the intake manifold pressure.

[0087] Rail pressure 906 can be provided by pressure sensor 16, which is operatively in communication with fuel rail 30 and configured to sense the pressure of fuel rail 30, which is configured to supply fuel to injector 12i and can also be configured to supply fuel to other injectors. Rail pressure 906 can be provided to injector control logic 910 via a dedicated connection or via one or more communication networks. Rail pressure 906 can be used as a rail pressure measurement as described above in conjunction with control logic 200, and can be repeatedly sampled to determine multiple points or values ​​of rail pressure measurement.

[0088] The rail temperature 908 can be provided by a temperature sensor 18, which is operatively in communication with the fuel rail 30 and configured to sense the temperature of the fuel rail 30. The rail temperature 908 can be provided to the injector control logic 910 via a dedicated connection or via one or more communication networks. The rail temperature 908 can be used as the rail temperature described above in conjunction with control logic 200, and can be repeatedly sampled to determine multiple points or values ​​of the rail temperature measurement.

[0089] Injector control logic 910 includes control circuitry configured to implement and execute control logic for processing inputs received by injector control logic 910, and configured to determine and output injector control signals 919. In the illustrated example, the circuitry of injector control logic 910 is configured to provide and execute pressure measurement processing logic 912, gaseous fuel characterization logic 914, injection control logic 916, and injection control modification logic 918. In other embodiments, the control logic provided by injector control logic 910 may be organized differently, wherein aspects of one or more logic blocks in the illustrated logic blocks are combined in a single block or unit, divided into multiple blocks or units, and / or provided with additional or alternative blocks or units.

[0090] In the illustrated example, pressure measurement processing logic 912 and gaseous fuel characterization logic 914 are configured to implement and execute one or more operations, such as the gaseous fuel sound velocity determination and gaseous fuel molecular mass determination techniques described herein. Pressure measurement processing logic 912 is configured to perform multiple operations related to the reception and processing of rail pressure 906. Gaseous fuel characterization logic 914 is configured to use the output of pressure measurement processing logic 912 to perform multiple operations related to the calculation of injected fuel quantity estimation. In other embodiments, the aforementioned operations may be distributed differently among or within pressure measurement processing logic 912, gaseous fuel characterization logic 914, and / or the additional injector control logic 910.

[0091] Injection control logic 916 is configured to determine an injector command to provide an output including an injector control signal 919. Injector control logic 916 can be configured to determine an injector opening time command that effectively sets the injector control signal 919 to an injector open state or value for a duration corresponding to the commanded injector opening time. Injector control logic 916 can determine the injector opening time command in response to a fuel filling command 902, engine speed 903, and intake manifold pressure (IMP) 904, rail pressure 906, and rail temperature 908, and can utilize various techniques to perform this determination.

[0092] In some embodiments, injector control logic 916 may be configured and set as one or more lookup tables, maps, or response surfaces, configured and operable to provide an injector opening time command in response to the aforementioned inputs. In some embodiments, injector control logic 916 may be configured to determine the injector opening time commanded for a given input value of engine speed 903, intake manifold pressure (IMP) 904, rail pressure 906, and rail temperature 908, based on a set of tables. It should be understood that intermediate values ​​may be determined using interpolation between sets of two or more tables, or between sets of two or more curves.

[0093] In some embodiments, the injector control logic 916 may be configured and operable to solve one or more equations in response to the aforementioned inputs to determine the injector opening time command. Equation (10) provides an example of an equation that can be utilized in this way: (10) in The time for the injectors to open under command. The injection volume at a defined reference temperature. The gas pressure at the fuel rail. This refers to the intake manifold pressure, and The coefficients can be determined empirically or derived from a physics-based model and can be adjusted to change the effect of equation (1).

[0094] The injector opening time command can also be determined using equations (11) and (12), where the opening and closing time delays of the injector can be expressed in the form of equations or tables.

[0095] (11) For the blocked flow state with the ratio of downstream pressure to supply pressure, the mass flow rate relationship of the gas ejector is given in equation (10), or for the non-blocked flow state with the ratio of downstream pressure to supply pressure, it is given in equation (11). The actual open flow duration of the ejector is shown in equation (12).

[0096] (12) The injector-on state of the injector control signal 919 effectively actuates the switch 934. The switch 934 is operatively connected to a system voltage source (V_supply) and configured to selectively supply injector current (I_inj) to the solenoid 124 of the injector 12. The injector current (I_inj) effectively energizes the solenoid 124 to cause a lifting movement of the injector armature 122 (sometimes referred to as the injector needle valve) in a direction generally indicated by arrow L. In the lifted position (illustrated in dashed form), the injector armature 122 allows fuel supplied to the injector passage 126 to be ejected from one or more orifices at the tip of the injector 12 as fuel injection (F_inj) into the port of the intake manifold 37 leading to the associated combustion chamber of the engine 10.

[0097] Injection control modification logic 918 is configured to modify the relationship between the injector opening time command and the injection quantity of the command utilized by injector control logic 916 as described above. In some embodiments, injection control modification logic 918 may be configured to modify one or more tables that define one or more relationships between the opening time of the command as a function of the injection quantity at a given gaseous fuel temperature and a given engine speed, as described above in conjunction with injector control logic 916. In some embodiments, injection control modification logic 918 may be configured to modify one or more coefficients of an equation that defines one or more relationships between the opening time of the command as a function of the injection quantity at a given gaseous fuel temperature and a given engine speed, as described above in conjunction with injector control logic 916. In some embodiments, injection control modification logic 918 may be configured to modify a value in an adaptive table or equation that defines one or more relationships between the opening time of the command as a function of the injection quantity at a given gaseous fuel temperature and a given engine speed, as described above in conjunction with injector control logic 916.

[0098] Injection control modification logic 918 can modify one or more of the aforementioned relationships between the injector opening time command and the commanded injection quantity by comparing a calculated estimate of the injected fuel quantity (such as the estimate determined in operator 214 of control 200) with an existing relational model. The existing relational model may include a set of lookup tables or equations.

[0099] Injection control modification logic 918 can compare a calculated fuel injection quantity estimate with a predicted injection quantity corresponding to engine speed and fuel rail temperature in one or more tables, for example, by determining the difference between the calculated fuel injection quantity estimate and the predicted injection quantity. The comparison of the difference can be used to modify the relationship between the injection quantity (Q) and the moving average pressure change (ΔP_avg) or the amplitude of the discrete Fourier transform at different ignition frequency ratios for a given engine speed and fuel rail temperature. The relationship between the injection quantity (Q) and the moving average pressure change (ΔP_avg) or the amplitude of the discrete Fourier transform at different ignition frequency ratios for a given engine speed and fuel rail temperature can be part of gaseous fuel characterization logic 914 used to estimate the injection quantity. The comparison of the difference between the commanded injection quantity and the estimated injection quantity can be used to modify one or more relationships used to determine the start time of the injection quantity (Q) command as a function of characteristics such as rail pressure, intake manifold pressure, engine speed, fuel temperature, and the characteristics of the operating gaseous fuel. In some embodiments, the modified relation may be incorporated into or used to modify one or more of a set of tables or equations used by the injector control logic 916. In some embodiments, the modified relation may be incorporated into or used to modify one or more coefficients of the equations used by the injector control logic 916.

[0100] It should be understood that additional tables may be provided in accordance with the tables according to this disclosure for other combinations of gaseous fuel temperature and engine speed. It should also be understood that intermediate values ​​may be determined using interpolation between sets of two or more tables, or between sets of two or more curves, given in this disclosure.

[0101] refer to Figure 21 Example control logic 300 exists, which can be implemented and executed by an electronic control system (e.g., ECS 20 or another electronic control system) operatively communicating with a fuel dispensing system (e.g., gaseous fuel dispensing system 9 or another fuel dispensing system). Control logic 300 can be implemented and executed in one or more components of the electronic control system (such as one or more electronic control units (e.g., ECU 22 and / or other electronic control units)) and by one or more components of the electronic control system and / or by other electronic control system components. Control logic 300 is an example of control logic in which gaseous fuel pressure and temperature measurements are used to estimate the characteristics of the gaseous fuel and fuel based on the time period associated with the measurement and the oscillation of the supply pressure after the injection event.

[0102] Control logic 300 can be executed during the operation of the engine system in a mission, so that no special or dedicated operating mode is required, although some modes may utilize special or dedicated operating modes, such as test mode or calibration mode.

[0103] Operator 200' determines one or more gaseous fuel sound velocity parameters in response to gaseous fuel and pressure. Operator 200' may include or utilize operations substantially similar to those described in conjunction with control logic 200. For example, operator 200' may include operators substantially similar to operators 202, 204, 205, 206, 207, 208, 210, 211, and 212 of control logic 200. Furthermore, operator 200' may determine and provide a gaseous fuel effective molecular mass parameter 311, such as a parameter substantially similar to that determined by operator 211 of control logic 200, and a gaseous fuel adiabatic index parameter 312, such as a parameter substantially similar to that determined by operator 212 of control logic 200.

[0104] The actuator 320 receives the effective molecular weight parameter 311 of the gaseous fuel and can determine a lower calorific value parameter in partial or complete response to the effective molecular weight parameter 311. The actuator 320 can use a predetermined relationship between the effective molecular weight parameter 311 of the gaseous fuel and the lower calorific value parameter, for example, a predetermined relationship between the relative change of the lower calorific value of the gaseous fuel and the average molecular weight of the gaseous fuel, to make this determination.

[0105] It should be understood that the lower calorific value parameter may include the lower calorific value itself, an estimated lower calorific value, or a parameter related to or from which the lower calorific value can be readily determined. Additionally or alternatively, the lower calorific value parameter may be predetermined using the physical relationships of different gaseous fuel mixtures. Furthermore, regardless of the specific source of the predetermined relationship between the effective molecular mass parameter of the gaseous fuel and the lower calorific value parameter, such predetermined relationship may be stored in one or more lookup tables, operation maps, equations, or other data or computational structures of control logic 300.

[0106] Figure 22 The figure illustrates a predetermined relationship between the effective molecular mass parameter 311 of gaseous fuel and the reduced calorific value parameter. Figure 22 The graph illustrates the relative (percentage) change in the lower calorific value (LHV) of the gaseous fuel at its vertical axis as a function of the average molecular mass of the gaseous fuel at its horizontal axis, for several example gaseous fuel mixtures under steady-state blocked flow conditions, with the same pressure, temperature, and dilution gas percentage.

[0107] exist Figure 22In the diagram, data point 402 corresponds to EPA-certified natural gas fuel ASTM D1954. Data point 404 corresponds to a mixture of 90% fuel and 10% hydrogen from data point 402. Data point 406 corresponds to a mixture of 80% fuel and 20% hydrogen from data point 402. As shown in curve 401, there is a proportional relationship between the percentage change in LHV of the example gaseous fuel mixture and the average molecular weight. It should be understood that predetermined relationships can be determined based on a wider range of example gaseous fuel mixtures, and such relationships can include various types of relationships between lower calorific value parameters and average molecular weight parameters.

[0108] Figure 23 The figure illustrates a predetermined relationship between the effective molecular mass parameter 311 of gaseous fuel and the reduced calorific value parameter. Figure 23 The graphs illustrate the relationship between the lower calorific value (LHV) of the gaseous fuel mixture on its vertical axis and its mass on its horizontal axis for several example gaseous fuel mixtures. Curve 502 depicts the relationship for gaseous fuel mixtures with less than 0.3% N2 molar percentage. Curve 504 depicts the relationship for gaseous fuel mixtures with approximately 4% N2 molar percentage. Curve 506 depicts the relationship for gaseous fuel mixtures with approximately 5.5% N2 molar percentage.

[0109] The operator 320 may also receive one or more engine output sensor measurements 318, which may be provided by one or more sensors configured to sense parameters indicating how engine output varies with the lower calorific value parameters of the burning gaseous fuel mixture. For example, an engine torque sensor, an engine exhaust oxygen (EGO) sensor, or a λ sensor may be used to provide input indicating engine torque or engine exhaust oxygen content (which is related to engine torque as an indication of complete or incomplete combustion). The variance between the actual engine torque or actual exhaust oxygen content and the expected engine torque or expected exhaust oxygen content can be used to determine that the percentage of diluent gases in the combustion air-fuel mixture is higher than the percentage expected for intake air, thus ultimately indicating the percentage of diluent gases in the gaseous fuel mixture. The operator 320 may use the determined percentage of diluent gases in the gaseous fuel mixture to adjust the determination of the lower calorific value parameter, for example, by adjusting on a percentage or proportional basis to account for the percentage of one or more diluent gases that may be non-flammable or inert and therefore do not contribute to the heat of combustion.

[0110] Operator 320 provides the determined lower calorific value parameter to operator 322, which also receives the effective molecular weight parameter 311 and the adiabatic index parameter 312 of the gaseous fuel. In response to these inputs, operator 322 sets further or more fuel system and engine control commands, such as injection mass, injection timing, ignition timing, intake manifold pressure, airflow, and other operational control parameters. Operator 324 may optionally store gaseous fuel mixture parameters (e.g., the determined lower calorific value parameter, the effective molecular weight parameter, and the adiabatic index parameter) and / or the determined operational control parameters for analysis, diagnosis, and prediction, for example, by appending such data to a data log storing the engine's gaseous fuel properties history. In some embodiments, operator 324 may store the engine's gaseous properties history, including an estimated hydrogen percentage history, which can be used in conjunction with the analysis, diagnosis, and prediction of performance and durability issues. The hydrogen percentage recording may be based on the fact that hydrogen has a low molecular weight of approximately 2 g / mol and thus reduces the average molecular weight of the natural gas mixture. Since the typical blend of natural gas is not less than 16.043 g / mol, which is the molecular weight of its normal lowest molecular weight component, methane, low molecular weight estimation measurements can be used to indicate the presence of hydrogen in the gaseous mixture.

[0111] As described in the detailed description, this disclosure contemplates multiple and various embodiments, including but not limited to the following example embodiments. A first example embodiment is a system comprising: an engine including a plurality of combustion cylinders; a fuel dispensing system including a fuel rail configured to receive a gaseous fuel mixture from a fuel supply source, a plurality of fuel injectors operatively in communication with the fuel rail and the plurality of combustion cylinders, and a pressure sensor system operatively coupled to the fuel rail and configured to provide an output indicating fuel pressure on the fuel rail; and an electronic control system operatively in communication with the fuel dispensing system and configured to: control the opening time of the plurality of fuel injectors to provide injection of the gaseous fuel mixture, determine fuel dispensing control parameters in response to the output of the pressure sensor system, change the fuel dispensing control parameters in response to a change in the average molecular weight of the gaseous fuel mixture, and adjust injector operating parameters in response to the change in the fuel dispensing control parameters.

[0112] The second example embodiment includes features of the first example embodiment, wherein the electronic control system is configured to: determine a sound velocity parameter of the gaseous fuel mixture in response to the output of the pressure sensor system, determine a gaseous fuel characteristic indicating the molecular mass of the fuel in response to the sound velocity parameter, and modify one or more of the injector opening time in response to the gaseous fuel characteristic.

[0113] The third example embodiment includes features of the second example embodiment, wherein the electronic control system configured to determine the speed of sound parameter includes the electronic control system configured to perform: receiving a first output corresponding to an injection event from a first pressure sensor of the pressure sensor system, the first pressure sensor being configured to sense fuel pressure associated with a first position on the fuel rail; receiving a second output corresponding to the injection event from a second pressure sensor of the pressure sensor system, the second pressure sensor being configured to sense fuel pressure associated with a second position on the fuel rail spaced apart from the first position; and determining the speed of sound parameter in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

[0114] The fourth example embodiment includes features of the third example embodiment, wherein the electronic control system configured to determine the speed of sound parameter includes the electronic control system configured to perform: receiving from a pressure sensor of the pressure sensor system a first output corresponding to a first injection event performed by a first injector of the fuel filling system, the first injector being spaced apart from the pressure sensor by a first distance; receiving from the pressure sensor a second output corresponding to a second injection event performed by a second injector of the fuel filling system, the second injector being spaced apart from the pressure sensor by a second distance different from the first distance; and determining the speed of sound parameter in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

[0115] The fifth example embodiment includes features of the second example embodiment, wherein the electronic control system configured to determine the sound speed parameter includes the electronic control system configured to perform: determining one or more inherent frequencies of the output of the pressure sensor of the pressure sensor system after a jet event; and determining the sound speed parameter in response to the one or more inherent frequencies.

[0116] The sixth example embodiment includes features of the fifth example embodiment, wherein the electronic control system is configured to determine the one or more natural frequencies using at least one of discrete Fourier transform (DFT) and sine-based curve fitting.

[0117] The seventh example embodiment includes features of the fifth example embodiment, wherein the electronic control system is configured to determine the sound speed parameter using a linear relationship between the sound speed parameter and the one or more natural frequencies.

[0118] The eighth example embodiment includes features of the fifth example embodiment, wherein the electronic control system is configured to determine the one or more inherent frequencies during engine operation under quasi-static conditions.

[0119] The ninth example embodiment includes features of the second example embodiment, wherein the electronic control system configured to determine the sound speed parameter includes the electronic control system configured to perform: determining the decaying oscillation period of the output of the pressure sensor of the pressure sensor system after a jet event; and determining the sound speed parameter in response to the decaying oscillation period.

[0120] The tenth example embodiment includes features of the ninth example embodiment, wherein the electronic control system is configured to perform at least one of the following: determining the damped oscillation period for a single injection event; determining the sound speed parameter using an inverse relationship between the sound speed parameter and the damped oscillation period; and determining the damped oscillation period during engine transient operation.

[0121] The eleventh example embodiment includes features of the second example embodiment, wherein the electronic control system configured to determine the sound speed parameter includes the electronic control system configured to perform the following: determining the maximum amplitude of the Fourier transform of the output of the pressure sensor system, and determining the sound speed parameter in response to the maximum amplitude.

[0122] The twelfth example embodiment includes the features of the eleventh example embodiment, wherein the Fourier transform of the output of the pressure sensor system includes a Fourier transform at the 1.5 engine ignition frequency harmonic.

[0123] The thirteenth example embodiment includes features of the first example embodiment, wherein the electronic control system configured to adjust injector operating parameters effectively mitigates changes in engine output in response to changes in the average molecular mass of the gaseous fuel mixture.

[0124] The fourteenth example embodiment includes features of the first example embodiment, wherein the electronic control system configured to adjust injector operating parameters effectively reduces the difference between the engine output and the actual engine output in response to a command to a change in the average molecular mass of the gaseous fuel mixture.

[0125] The fifteenth example embodiment is a method for controlling a system including an engine and a fuel dispensing system. The engine includes a plurality of combustion cylinders, and the fuel dispensing system includes: a fuel rail configured to receive a gaseous fuel mixture from a fuel supply source; a plurality of fuel injectors operatively communicating with the fuel rail and the plurality of combustion cylinders; and a pressure sensor system operatively coupled to the fuel rail and configured to provide an output indicating fuel pressure on the fuel rail. The method includes: controlling the opening time of the plurality of fuel injectors to provide injection of the gaseous fuel mixture; determining fuel dispensing control parameters in response to the output of the pressure sensor system; changing the fuel dispensing control parameters in response to a change in the average molecular weight of the gaseous fuel mixture; and adjusting injector operating parameters in response to the change in the fuel dispensing control parameters.

[0126] The sixteenth example embodiment includes features of the fifteenth example embodiment, including: determining a sound velocity parameter of the gaseous fuel mixture in response to the output of the pressure sensor system, determining a gaseous fuel characteristic indicating the molecular mass of the fuel in response to the sound velocity parameter, and modifying one or more of the injector opening time in response to the gaseous fuel characteristic.

[0127] The seventeenth example embodiment includes features of the sixteenth example embodiment, wherein determining the speed of sound parameter comprises: receiving a first output corresponding to an injection event from a first pressure sensor of the pressure sensor system, the first pressure sensor being configured to sense fuel pressure associated with a first position on the fuel rail; receiving a second output corresponding to the injection event from a second pressure sensor of the pressure sensor system, the second pressure sensor being configured to sense fuel pressure associated with a second position on the fuel rail spaced apart from the first position; and determining the speed of sound parameter in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

[0128] The eighteenth example embodiment includes features of the seventeenth example embodiment, wherein determining the speed of sound parameter comprises: receiving from a pressure sensor of the pressure sensor system a first output corresponding to a first injection event performed by a first injector of the fuel filling system, the first injector being spaced apart from the pressure sensor by a first distance; receiving from the pressure sensor a second output corresponding to a second injection event performed by a second injector of the fuel filling system, the second injector being spaced apart from the pressure sensor by a second distance different from the first distance; and determining the speed of sound parameter in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

[0129] The nineteenth example embodiment includes the features of the sixteenth example embodiment, wherein determining the speed of sound parameter includes: determining one or more inherent frequencies of the output of the pressure sensor of the pressure sensor system after the jet event; and determining the speed of sound parameter in response to the one or more inherent frequencies.

[0130] The twentieth example embodiment includes the features of the nineteenth example embodiment, wherein the determination of the one or more natural frequencies uses at least one of discrete Fourier transform (DFT) and sine-based curve fitting.

[0131] The twenty-first example embodiment includes the features of the nineteenth example embodiment, wherein the sound speed parameter is determined using a linear relationship between the sound speed parameter and the one or more natural frequencies.

[0132] The twenty-second example embodiment includes features of the nineteenth example embodiment, wherein determining the one or more inherent frequencies is performed during engine operation under quasi-static conditions.

[0133] The twenty-third example embodiment includes the features of the sixteenth example embodiment, wherein determining the sound speed parameter includes: determining the decaying oscillation period of the output of the pressure sensor of the pressure sensor system after the jet event; and determining the sound speed parameter in response to the decaying oscillation period.

[0134] The twenty-fourth example embodiment includes features of the twenty-third example embodiment, including at least one of the following: determining the decaying oscillation period for a single injection event; determining the sound speed parameter using an inverse relationship between the sound speed parameter and the decaying oscillation period; and determining the decaying oscillation period during the engine transient operation.

[0135] The twenty-fifth example embodiment includes the features of the sixteenth example embodiment, wherein determining the sound speed parameter includes: determining the maximum amplitude of the Fourier transform of the output of the pressure sensor system, and determining the sound speed parameter in response to the maximum amplitude.

[0136] The twenty-sixth example embodiment includes the features of the twenty-fifth example embodiment, wherein the Fourier transform of the output of the pressure sensor system includes a Fourier transform at the 1.5 engine ignition frequency harmonic.

[0137] The twenty-seventh example embodiment includes the features of the fifteenth example embodiment, wherein adjusting the injector operating parameters effectively mitigates changes in engine output in response to changes in the average molecular mass of the gaseous fuel mixture.

[0138] The twenty-eighth example embodiment includes features of the fifteenth example embodiment, wherein adjusting the injector operating parameters effectively reduces the difference between the engine output and the actual engine output in response to a command to a change in the average molecular mass of the gaseous fuel mixture.

[0139] It should be understood that this disclosure envisions numerous gaseous fuel systems, including the ability to identify gaseous characteristics that affect engine and fuel system operation. In some embodiments, the gaseous fuel identification method can be performed during normal engine operation in the field. In some embodiments, measurements for gaseous fuel identification purposes can be performed without interfering with normal or pre-measurement operation. In some embodiments, gaseous fuel estimation can be used for purposes such as engine on-board adaptation to engine and fuel system commands to account for performance differences between alternative gaseous fuels, closed-loop injection quantity control, and engine and fuel system prediction and diagnostics.

[0140] It should be understood that terms such as “non-transitory memory,” “non-transitory memory medium,” and “non-transitory memory device” refer to various types of devices and storage media that can be configured to store information (such as data or instructions) that can be read or executed by a processor or other component of a computer system, and such terms include and cover a single or single device or medium storing such information, multiple devices or media storing corresponding portions of such information across or in it, and multiple devices or media storing multiple copies of such information across or in it.

[0141] It should be understood that when used in conjunction with control methods or processes, electronic control systems or controllers, electronic control, or the aforementioned components or operations, terms such as “determine,” “determined,” and “determining” inclusively refer, individually or in combination, to any of a number of actions, configurations, devices, operations, and techniques, including but not limited to the calculation or computation of parameters or values, obtaining parameters or values ​​from lookup tables or using lookup operations, receiving parameters or values ​​from data links or network communications, receiving electronic signals indicating parameters or values ​​(e.g., voltage, frequency, current, or pulse width modulation (PWM) signals), receiving the output of sensors indicating parameters or values, receiving other outputs or inputs indicating parameters or values, reading parameters or values ​​from memory locations on computer-readable media, receiving parameters or values ​​as runtime parameters, and / or by receiving parameters or values ​​that can be calculated and interpreted as parameters, and / or by referring to default values ​​interpreted as parameter values.

[0142] While exemplary embodiments of the present disclosure have been shown and described in detail in the accompanying drawings and the foregoing description, they are intended to be illustrative rather than restrictive in character. It should be understood that only certain exemplary embodiments have been shown and described, and protection is intended for all changes and modifications falling within the spirit of the claimed invention. It should be understood that while the use of terms such as preferred, preferably, or more preferred in the foregoing description indicates that the features so described may be more desirable, this may not be necessary, and embodiments lacking these may be contemplated as being within the scope of the invention, defined by the appended claims. When reading the claims, it is intended that the use of terms such as “a,” “an,” “at least one,” or “at least a portion” is not intended to limit the claims to only one item, unless expressly stated to the contrary in the claims. When the language “at least a portion” and / or “a portion” is used, an item may include a portion and / or the entire item, unless expressly stated otherwise.

Claims

1. A system comprising: An engine, the engine comprising multiple combustion cylinders; A fuel filling system comprising: a fuel rail configured to receive a gaseous fuel mixture from a fuel supply source; a plurality of fuel injectors operatively communicating with the fuel rail and the plurality of combustion cylinders; and a pressure sensor system operatively coupled to the fuel rail and configured to provide an output indicating the fuel pressure of the fuel rail; and An electronic control system, which is operatively communicative with the fuel dispensing system and configured to: The opening time of the plurality of fuel injectors is controlled to provide injection of the gaseous fuel mixture. The fuel filling control parameters are determined in response to the output of the pressure sensor system. The fuel dispensing control parameters are changed in response to changes in the average molecular weight of the gaseous fuel mixture, and The injector operating parameters are adjusted in response to changes in the fuel filling control parameters.

2. The system of claim 1, wherein the electronic control system is configured to: The speed of sound parameters of the gaseous fuel mixture are determined in response to the output of the pressure sensor system. In response to the sound velocity parameter, the gaseous fuel characteristics indicating the molecular mass of the fuel are determined, and One or more of the injector opening times are modified in response to the gaseous fuel characteristics.

3. The system of claim 2, wherein the electronic control system configured to determine the sound speed parameter comprises the electronic control system configured to perform the following: A first output corresponding to an injection event is received from a first pressure sensor of the pressure sensor system, the first pressure sensor being configured to sense fuel pressure associated with a first position on the fuel rail; A second output corresponding to the injection event is received from a second pressure sensor of the pressure sensor system, the second pressure sensor being configured to sense fuel pressure associated with a second position on the fuel rail spaced apart from the first position; as well as The sound speed parameter is determined in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

4. The system of claim 3, wherein the electronic control system configured to determine the sound speed parameter comprises the electronic control system configured to perform the following: The pressure sensor of the pressure sensor system receives a first output corresponding to a first injection event performed by a first injector of the fuel filling system, the first injector being spaced a first distance from the pressure sensor; The pressure sensor receives a second output corresponding to a second injection event performed by a second injector of the fuel filling system, the second injector being spaced from the pressure sensor at a second distance different from the first distance; as well as The sound speed parameter is determined in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

5. The system of claim 2, wherein the electronic control system configured to determine the sound speed parameter comprises the electronic control system configured to perform: Determine one or more inherent frequencies of the pressure sensor output of the pressure sensor system after the injection event; and The sound speed parameter is determined in response to one or more inherent frequencies.

6. The system of claim 5, wherein the electronic control system is configured to determine the one or more natural frequencies using at least one of discrete Fourier transform (DFT) and sine-based curve fitting.

7. The system of claim 5, wherein the electronic control system is configured to determine the sound speed parameter using a linear relationship between the sound speed parameter and the one or more natural frequencies.

8. The system of claim 5, wherein the electronic control system is configured to determine the one or more inherent frequencies during engine operation under quasi-static conditions.

9. The system of claim 2, wherein the electronic control system configured to determine the sound speed parameter comprises the electronic control system configured to perform: Determine the decaying oscillation period of the pressure sensor output of the pressure sensor system after the injection event; and The sound speed parameter is determined in response to the damped oscillation period.

10. The system of claim 9, wherein the electronic control system is configured to perform at least one of the following: Determine the decaying oscillation period for a single injection event; The sound velocity parameter is determined using the inverse relationship between the sound velocity parameter and the decaying oscillation period; and Determine the damped oscillation period during the transient operation of the engine.

11. The system of claim 2, wherein the electronic control system configured to determine the sound speed parameter comprises the electronic control system configured to perform: Determine the maximum amplitude of the Fourier transform of the output of the pressure sensor system, and The sound speed parameter is determined in response to the maximum amplitude.

12. The system of claim 11, wherein the Fourier transform of the output of the pressure sensor system comprises a Fourier transform at the 1.5 engine ignition frequency harmonic.

13. The system of claim 1, wherein the electronic control system configured to adjust injector operating parameters effectively mitigates changes in engine output in response to changes in the average molecular mass of the gaseous fuel mixture.

14. The system of claim 1, wherein the electronic control system configured to adjust injector operating parameters effectively reduces the difference between the engine output and the actual engine output in response to a command to a change in the average molecular mass of the gaseous fuel mixture.

15. A method for controlling a system comprising an engine and a fueling system, the engine comprising a plurality of combustion cylinders, the fueling system comprising: A fuel rail, configured to receive a gaseous fuel mixture from a fuel supply source; Multiple fuel injectors, the multiple fuel injectors being operatively in communication with the fuel rail and the multiple combustion cylinders; The method includes a pressure sensor system operatively coupled to the fuel rail and configured to provide an output indicating the fuel pressure of the fuel rail. The opening time of the plurality of fuel injectors is controlled to provide injection of the gaseous fuel mixture. The fuel filling control parameters are determined in response to the output of the pressure sensor system. The fuel dispensing control parameters are changed in response to changes in the average molecular weight of the gaseous fuel mixture, and The injector operating parameters are adjusted in response to changes in the fuel filling control parameters.

16. The method of claim 15, comprising: The speed of sound parameters of the gaseous fuel mixture are determined in response to the output of the pressure sensor system. In response to the sound velocity parameter, the gaseous fuel characteristics indicating the molecular mass of the fuel are determined, and One or more of the injector opening times are modified in response to the gaseous fuel characteristics.

17. The method of claim 16, wherein determining the sound speed parameter comprises: A first output corresponding to an injection event is received from a first pressure sensor of the pressure sensor system, the first pressure sensor being configured to sense fuel pressure associated with a first position on the fuel rail; A second output corresponding to the injection event is received from a second pressure sensor of the pressure sensor system, the second pressure sensor being configured to sense fuel pressure associated with a second position on the fuel rail spaced apart from the first position; as well as The sound speed parameter is determined in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

18. The method of claim 17, wherein determining the sound speed parameter comprises: The pressure sensor of the pressure sensor system receives a first output corresponding to a first injection event performed by a first injector of the fuel filling system, the first injector being spaced a first distance from the pressure sensor; The pressure sensor receives a second output corresponding to a second injection event performed by a second injector of the fuel filling system, the second injector being spaced from the pressure sensor at a second distance different from the first distance; as well as The sound speed parameter is determined in response to the difference between the first output and the second output, and the difference between the distance between the first pressure sensor and the injector performing the first injection event and the distance between the second pressure sensor and the injector performing the first injection event.

19. The method of claim 16, wherein determining the sound speed parameter comprises: Determine one or more inherent frequencies of the pressure sensor output of the pressure sensor system after the injection event; as well as The sound speed parameter is determined in response to one or more inherent frequencies.

20. The method of claim 19, wherein the determination of the one or more natural frequencies uses at least one of discrete Fourier transform (DFT) and sine-based curve fitting.

21. The method of claim 19, wherein the sound speed parameter is determined using a linear relationship between the sound speed parameter and the one or more natural frequencies.

22. The method of claim 19, wherein determining the one or more natural frequencies is performed during operation of the engine under quasi-static conditions.

23. The method of claim 16, wherein determining the sound speed parameter comprises: Determine the decay oscillation period of the pressure sensor output of the pressure sensor system after the injection event; as well as The sound speed parameter is determined in response to the damped oscillation period.

24. The method of claim 23, comprising at least one of the following: Determine the decaying oscillation period for a single injection event; The sound velocity parameter is determined using the inverse relationship between the sound velocity parameter and the decaying oscillation period; and Determine the damped oscillation period during the transient operation of the engine.

25. The method of claim 16, wherein determining the sound speed parameter comprises: Determine the maximum amplitude of the Fourier transform of the output of the pressure sensor system, and The sound speed parameter is determined in response to the maximum amplitude.

26. The method of claim 25, wherein the Fourier transform of the output of the pressure sensor system comprises a Fourier transform at the 1.5 engine ignition frequency harmonic.

27. The method of claim 15, wherein adjusting the injector operating parameters effectively mitigates changes in engine output in response to changes in the average molecular mass of the gaseous fuel mixture.

28. The method of claim 15, wherein adjusting the injector operating parameters effectively reduces the difference between the engine output and the actual engine output in response to a command in response to a change in the average molecular mass of the gaseous fuel mixture.

Images