System and method for controlling fuel replacement in a dual fuel engine system

Abstract

The invention relates to a system and method for controlling fuel replacement in a dual fuel engine system. A method of controlling a dual fuel engine configured to receive a first fuel and a second fuel includes operating the engine using the first fuel, measuring a current load of the engine, sending a first signal to a first fuel system to deliver a quantity of the first fuel to the engine, and transmitting a second signal to a second fuel system to deliver a quantity of the second fuel to the engine. And determining at least one first operating parameter associated with the engine. The method further includes determining an engine load estimate based on the first signal and at least one first operating parameter, comparing the engine load estimate to the measured load, and determining an adjusted engine load estimate to compensate for drift in the first fuel system based on the comparison.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 538,784, filed on September 15, 2023, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to methods for controlling a dual fuel engine system. Background Art

[0004] Generally, a dual fuel engine system may include an original equipment manufacturer (OEM) machine control system, a base engine control system or module (ECM) operably coupled to the OEM machine control system, and a gas control system operably coupled to both the OEM machine control system and the base engine control system. Summary of the invention

[0005] One aspect of the present disclosure relates to a method of controlling a dual fuel engine configured to receive a first fuel and a second fuel. The method includes operating the engine using the first fuel, measuring, by a controller, a current load of the engine, and sending, by the controller, a first signal to a first fuel system to deliver a quantity of the first fuel to the engine. The method also includes determining, by the controller, at least one first operating parameter associated with the engine, determining, by the controller, an engine load estimate based on the first signal and the at least one first operating parameter, comparing, by the controller, the engine load estimate to the measured current load, and determining, by the controller, an adjusted engine load estimate based on the comparison to compensate for drift in the first fuel system.

[0006] In various embodiments, the method further includes determining, by the controller, an amount of a second fuel to be delivered to the engine. In some embodiments, determining the amount of the second fuel to be delivered to the engine is based on comparing the engine load estimate with the measured current load. In other embodiments, the method further includes operating the engine by the controller using the adjusted engine load estimate within one cycle of a predetermined number of cycles or within a predetermined time period, wherein the amount of the second fuel is determined based on at least one second operating parameter determined during the predetermined number of cycles or the predetermined time period. In yet other embodiments, the method further includes determining, by the controller, a parasitic load on the engine. In various embodiments, determining the parasitic load on the engine includes determining, by the controller, a load corresponding to at least one cooling fan. In some embodiments, determining the engine load estimate includes determining, by the controller, a net engine load. In other embodiments, determining the net engine load includes estimating, by the controller, a gross engine load and subtracting the parasitic load.

[0007] Another aspect of the present disclosure relates to a dual-fuel engine system. The dual-fuel engine system includes an engine configured to receive a first fuel and a second fuel, a first fuel system for delivering the first fuel to the engine, a second fuel system for delivering the second fuel to the engine, and a controller operably coupled to each of the engine, the first fuel system, and the second fuel system. The controller is configured to: transmit a first signal to one of the first fuel system or the second fuel system to cause the first fuel system or the second fuel system to deliver a certain amount of the corresponding first fuel or second fuel, measure a current engine load, determine at least one first operating parameter of the engine, determine an engine load estimate based on the at least one first operating parameter and the amount of the first fuel or the second fuel, compare the engine load estimate with the current engine load, and determine an adjusted engine load estimate based on the comparison to compensate for drift in one of the first fuel or the second fuel.

[0008] In various embodiments, the controller is also configured to determine the amount of another fuel in the first fuel or the second fuel to be delivered to the engine. In some embodiments, the controller is configured to determine the amount of another fuel in the first fuel or the second fuel based on at least one second operating parameter. In other embodiments, the current engine load is based on at least one of the engine torque or the engine speed. In other embodiments, the dual-fuel engine system also includes a generator driven by the engine, wherein the current engine load is based on the current and voltage corresponding to the generator. In various embodiments, at least one first operating parameter includes at least one of the following: engine speed, coolant temperature, oil temperature, coolant pressure, oil pressure, intake manifold pressure, intake manifold temperature, exhaust manifold temperature, exhaust manifold pressure, injection timing or injection pressure. In some embodiments, the first signal includes at least one of the following: an electrical signal, a hydraulic parameter or a mechanical adjustment.

[0009] This summary is illustrative only and is not to be construed as limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements, and in which:

[0011] Figure 1 is a block diagram of a dual fuel engine system according to at least one embodiment.

[0012] Figure 2 According to at least one embodiment, Figure 1 Block diagram of the control system of a dual-fuel engine system.

[0013] Figure 3 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0014] Figure 4 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0015] Figure 5 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0016] Figure 6 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0017] Figure 7 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0018] Figure 8 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0019] Fig. 9 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0020] Fig.10 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0021] Fig.11 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0022] Fig.12 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0023] Fig.13 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0024] Fig.14 is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system.

[0025] Fig.15is a diagram showing a method according to at least one embodiment of the present invention. Figure 2 A flow chart of a method performed by a control system. DETAILED DESCRIPTION

[0026] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. In the accompanying drawings, similar symbols generally identify similar parts unless the context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be employed and other changes may be made without departing from the spirit or scope of the subject matter described herein. It will be readily understood that the various aspects of the present disclosure, as generally described herein and illustrated in the accompanying drawings, may be arranged, substituted, combined, and designed in a variety of different configurations, all of which are contemplated and form a part of the present disclosure.

[0027] The present disclosure relates at least in part to systems and methods for providing reduced operating costs, improved efficiency and / or improved performance of dual-fuel engine systems. In some embodiments, such systems and methods allow target emission levels to be met. In some embodiments, the scheme for controlling the dual-fuel engine system is adjustable to simplify, for example, the interfacing between the diesel engine ECM, the gas controller, and the OEM controller. In various embodiments, the dual-fuel engine system (and associated operating methods) is customized to maximize the use of cheaper gaseous fuels and minimize the use of diesel fuels while meeting performance requirements and emission requirements and maintaining robust engine protection. In particular, in order to meet Tier 4 emission regulations with a dual-fuel engine system, it is necessary to accurately and robustly control the dual-fuel engine system. This accurate and robust control includes, but is not limited to, control of the following: a gaseous or liquid fuel system, a second fuel type system (e.g., diesel, gas, etc.), and an aftertreatment system included in the dual-fuel engine system. The present disclosure outlines a system and method for precise and robust control of a dual-fuel engine system, including accurately determining (e.g., by measurement or estimation) a plurality of engine parameters (e.g., brake power, friction power, accessory power, first fuel (e.g., diesel, gas, liquid fuel) power, second fuel (e.g., gas, liquid) power, second fuel (e.g., gas, liquid) substitution rate, fuel quality parameters associated with the second fuel (e.g., methane number), LHV, second fuel (e.g., gas, liquid) temperature, second fuel (e.g., gas, liquid) pressure, knock intensity, exhaust temperature, etc.), and using the determined parameters as inputs for determining appropriate commands for one or more actuators within the dual-fuel engine system. The systems and methods described herein are applicable to new engine builds or for retrofitting onto existing Tier 4 diesel engine systems. Advantageously, the systems and methods described herein are lower in cost and complexity than typical port gas injection or cylinder pressure sensing systems.

[0028] refer to Figure 1, a block diagram of a dual fuel engine system 10 according to an exemplary embodiment is shown. The dual fuel engine system 10 is configured as an engine with a dual fuel operating mode, and the engine is configured to operate using two different fuels. The engine can be configured to operate using a first fuel and a second fuel, wherein the first fuel and the second fuel have different properties and / or chemical compositions. These properties may include autoignition temperature, flame speed, etc. The fuel may include, for example, diesel and natural gas. For example, the first fuel may be diesel fuel. The second fuel may be, for example, natural gas, e-fuel, or a liquid biofuel. The liquid biofuel may be, for example, methanol and / or ethanol. The first fuel or the second fuel can be any one of high cetane number fuel (high cetane number fuel), such as diesel, gas-to-liquid (gas-to-liquid, GTL) diesel, heavy fuel oil (HFO), low sulfur fuel oil (LFSO), hydrotreated vegetable oil (HVO), marine light diesel (MGO), renewable diesel, biodiesel, paraffin diesel, dimethyl ether (DME), F-76 fuel, F-34 fuel, jet A fuel, JP-4 fuel, JP-8 fuel or formaldehyde ether (OME) or low cetane number fuel (e.g., high octane fuel, high methane number fuel). Low cetane number fuel can be natural gas, hydrogen, ethane, propane, butane, synthesis gas, ammonia, methanol, ethanol or gasoline. The first fuel and / or the second fuel can be alternatively a mixture of fuels. It should be appreciated that the aforementioned is only an example of fuel, and does not exclude the first fuel and the second fuel of other types. In various embodiments, the dual fuel engine system 10 is configured for use in one or more oil and gas production applications (eg, land-based oil and / or gas drilling and hydraulic fracturing).

[0029] like Figure 1As shown, the dual-fuel engine system includes an internal combustion engine 20, which is operably coupled to a control system 11 via at least one controller 18. The control system 11, which includes a machine control system (OEM system) 12, a first fuel control system 14, and a second fuel control system 16, is configured to send one or more inputs to the controller 18, wherein the controller 18 then controls the internal combustion engine 20. In various embodiments, the first fuel control system 14 and its components are configured to operate using a first fuel. In other embodiments, the second fuel control system 16 and its components are configured to operate using a second fuel. For example, in various embodiments, the first fuel control system 14 is a diesel control system, and the second fuel control system 16 is a gas control system. In other embodiments, the first fuel control system 14 is a first gas control system, and the second fuel control system 16 is a second gas control system. In still other embodiments, one or both of the first fuel control system 14 and the second fuel control system 16 can be a liquid fuel control system.

[0030] In still other embodiments, the first fuel control system 14 and its components are configured to operate using the second fuel, and the second fuel control system 16 and its components are configured to operate using the first fuel. In still other embodiments, each of the first fuel control system 14 and the second fuel control system 16 and their respective components can selectively operate using the first fuel or the second fuel. In various embodiments, the first fuel control system 14 and the second fuel control system 16 operate cooperatively within the internal combustion engine 20.

[0031] In various embodiments, the controller 18 is configured to include a processor and a non-transitory computer-readable medium (e.g., a memory device) having computer-readable instructions stored thereon, which, when executed by the processor, causes at least one controller 18 to perform one or more operations. In various embodiments, at least one controller 18 is a computing device (e.g., a microcomputer, a microcontroller, or a microprocessor). In other embodiments, at least one controller 18 is configured as part of a data cloud computing system that is configured to receive commands from a user control device and / or a remote computing device.

[0032] The following description generally relates to a system in which the first fuel control system 14 operates using a first fuel and the second fuel control system 16 operates using a second fuel, however it should be understood that in other embodiments, each of the first fuel control system 14 and the second fuel control system 16 can be selectively configured to operate using the first fuel or the second fuel as described above. The controller 18 is also operably coupled to at least one second fuel injector 28 (to facilitate injection of the second fuel), at least one second fuel heater 32 configured to heat the second fuel, and at least one actuator 33. In some embodiments, the second fuel injector 28 is a gas injector. In other embodiments, the second fuel injector 28 is a liquid fuel injector. In various embodiments, at least one second fuel heater 32 is a gas heater configured to heat a gas. In some embodiments, at least one second fuel heater 32 is a liquid fuel heater configured to heat a liquid fuel. In other embodiments, the dual fuel engine system 10 does not include a second fuel heater. In some embodiments, each of the second fuel injector 28, the heater 32, and the actuator 33 is operably coupled to the internal combustion engine 20. In various embodiments, the second fuel injector 28 is configured to control or facilitate injection of a second fuel (e.g., gas or liquid, or a second gas) into the internal combustion engine 20. At least one second fuel heater 32 is configured to adjust the temperature of the second fuel flowing within the internal combustion engine 20. The actuator 33 may include one or more first fuel type (e.g., diesel type or other liquid type, first gas type) actuators, air handling actuators, aftertreatment actuators, or any other type of actuator within the dual fuel engine system 10. Thus, during operation, the controller 18 may send one or more inputs to one or more of the internal combustion engine 20, the second fuel injector 28, the heater 32, or the actuator 33 to facilitate a desired operating mode of the dual fuel engine system 10.

[0033] As shown, the internal combustion engine 20 includes an output shaft 24 and may also include one or more accessories 22. The internal combustion engine 20 also includes at least one manifold 26. In various embodiments, the at least one manifold 26 includes, but is not limited to, an intake manifold. The internal combustion engine 20 also includes at least one engine cylinder bank. In some embodiments, the at least one engine cylinder bank includes a left bank 30 and a right bank 31. During operation of the dual-fuel engine system 10, the control system 11 may receive one or more inputs from a user and / or one or more sensors within the dual-fuel engine system 10, and control the operation of at least one of the internal combustion engine 20, the second fuel injector 28, or the actuator 33 via the controller 18.

[0034] Figure 2is a block diagram of a control system 11 of a dual fuel engine system 10, according to an exemplary embodiment. As shown, the OEM system 12 may include one or more sensors 35, each coupled to one or more corresponding components within the dual fuel engine system 10. In various embodiments, the one or more sensors 35 may be operably coupled to or in communication with: a frac pump, accessories, one or more inlets or outlets of the internal combustion engine 20, or any other component within the dual fuel engine system 10 (e.g., a cooling fan, a flywheel, a brake, etc.). The OEM system 12 may include one or more processors configured to receive inputs from the sensors 35. In various embodiments, the one or more inputs from the sensors 35 may include a power estimate, a frac pump speed, a frac pump discharge pressure, a dual fuel mode activation request, or any other input detectable by the one or more sensors 35. As shown, the OEM system 12 may be communicatively coupled to each of the first fuel control system 14 and the second fuel control system 16 , wherein the OEM system 12 may output information sensed by one or more sensors 35 or may receive input from the first fuel control system 14 and / or the second fuel control system 16 .

[0035] like Figure 2 As shown, the first fuel control system 14 includes one or more sensors 40 that are coupled to one or more components within the internal combustion engine 20 or are disposed adjacent to one or more components within the internal combustion engine 20. In various embodiments, the one or more sensors 40 may be configured to determine (e.g., sense, detect, measure) at least one of the following: engine speed, intake manifold temperature, engine coolant temperature, oil temperature, cooling fan duty cycle, first fuel (e.g., diesel, first gas or other liquid) rate, or operating state of a dual fuel mode switch 55. In various embodiments, the dual fuel mode switch 55 may be configured to switch the operation of the internal combustion engine 20 between a single fuel mode or a dual fuel mode. Additionally or alternatively, the one or more sensors 40 may be configured to determine a lower heating value (LHV) of a second fuel (e.g., gas, liquid, or second gas). In still other embodiments, the one or more sensors 40 may be configured to determine one or more parameters indicative of the LHV, which may include, but are not limited to, a second fuel (e.g., gas, liquid, or second gas) density or a speed of sound. The first fuel control system 14 also includes an engine speed governor 50 . In various embodiments, the engine speed governor 50 may include one or more controllers configured to control the speed of the internal combustion engine 20 .

[0036] The first fuel (e.g., diesel or first gas) control system 14 also includes a first fuel (e.g., diesel or first gas) engine control system (ECM) and a torque fueling calculations module 45. In various embodiments, the torque fueling calculations module 45 may include one or more processors in communication with one or more reference databases or repositories, wherein the one or more processors are configured to reference data stored in the databases in order to perform torque calculations associated with the internal combustion engine 20. For example, in various embodiments, the torque fueling calculations module 45 is configured to calculate torque based on one or more known parameters. In various embodiments, the module 45 is configured to receive inputs corresponding to: dual fuel mode operating conditions, engine friction parameters, accessory ("parasitic") torque parameters, engine speed, OEM machine power estimates, and engine accessory power estimates (e.g., gas controller, liquid fuel controller, flywheel, etc.). In various embodiments, the one or more reference databases or repositories may include a lookup table 65. In various embodiments, the one or more lookup tables 65 include one or more chi-squared tables. In various embodiments, the lookup table 65 may include reference information related to the following items: engine torque, engine speed, engine friction parameter, parasitic parameter or accessory torque parameter, fuel rate of the first fuel (e.g., diesel or first gas), intake manifold temperature and / or engine coolant temperature. In various embodiments, the engine friction parameter of the lookup table 65 may be based on at least one of the oil temperature or the coolant temperature. In some embodiments, the parasitic parameter or torque parameter of the lookup table 65 may be based on the cooling fan duty cycle (i.e., the cooling fan duty cycle of the cooling fan in the internal combustion engine 20). In various embodiments, the module 45 is configured to determine at least one of the following: the total fueling amount of the first fuel (e.g., diesel or first gas), the approximate equivalent total fueling amount, the equivalent total fueling amount (i.e., the fueling equivalent of the second fuel of the fueling amount of the first fuel), the friction torque estimate, or the first fuel rate.

[0037] The first fuel control system 14 also includes a first fuel (e.g., diesel or first gas) air handling, aftertreatment and fuel system reference determination and control module 60. In various embodiments, the control module 60 may include at least one processor in communication with a database (e.g., a lookup table) 75. In various embodiments, the database 75 includes a data repository related to the following items: engine speed, fuel fill (e.g., equivalent total fuel fill, approximate equivalent total fuel fill), second fuel (e.g., gas, liquid or second gas) substitution rate (G / D), compressor inlet density (CID) or any other relevant parameters. Therefore, one or more processors within the control module 60 are configured to reference the data stored in the database 75 to determine one or more system inputs for at least one of the air handling control system 80, aftertreatment control system 85 or first fuel control system 90. In various embodiments, the one or more system inputs include, but are not limited to, actuator commands or targets (e.g., set points, operating thresholds, etc.) for at least one of the first fuel air handling control system 80, aftertreatment control system 85 or first fuel control system 90.

[0038] like Figure 2As shown, the second fuel (e.g., gas, liquid, or second gas) control system 16 may include one or more sensors 95 coupled to or disposed adjacent to one or more components within the internal combustion engine 20. In various embodiments, the one or more sensors 95 may be configured to determine (e.g., sense, detect, measure, etc.) at least one of the following: OEM machine torque, accessory torque, fuel quality parameter associated with the second fuel, second fuel injector pressure, second fuel supply pressure, second fuel flow, engine block exhaust temperature, aftertreatment system temperature, LHV, second fuel temperature, dual fuel mode input, knock intensity, G / D, or any other relevant parameter. In various embodiments, the fuel quality parameter associated with the second fuel may be a knock propensity indicator or a knock propensity index. In some embodiments, a knock propensity index (KPI) may be an index that associates a fuel composition (i.e., of the second fuel) with a knock propensity of an engine (i.e., engine 20) operating with the fuel (i.e., the second fuel). In some embodiments, the KPI may be a methane number (MN), an octane number, an anti-knock index (AKI), or any other parameter known in the art. In various embodiments, when the second fuel is natural gas, the KPI may be a MN. In various embodiments, when the second fuel is gasoline, the KPI may be an octane number or an AKI. In some embodiments, the engine group exhaust temperature may correspond to the left group average exhaust temperature and / or the right group average exhaust temperature. In some embodiments, the group average exhaust temperature may be calculated by averaging the measurements from the various exhaust port temperature sensors. In some embodiments, the exhaust port temperature sensor may be among at least one sensor 35, 40, and / or 95. The second fuel control system 16 also includes an OEM machine power and accessory power estimation module 130. In various embodiments, the OEM machine power and accessory power estimation module 130 may include one or more processors configured to estimate the OEM machine power and / or accessory power based on one or more inputs received by one or more sensors 95 (and / or from sensors 35, 40). In some embodiments, the accessory power may be power associated with one or more accessory components and / or an output shaft (e.g., output shaft 24) within the dual fuel engine system 10. In various embodiments, the OEM machine power and accessory power estimation module 130 is configured to receive inputs related to the OEM machine power estimate, accessory torque measurements, pump speed, pump discharge pressure, and engine speed, wherein one or more processors then estimate an accessory power estimate based on the inputs.Similarly, the second fuel control system 16 also includes a KPI (e.g., MN) estimation module 125. In various embodiments, the KPI estimation module 125 may include one or more processors configured to estimate a KPI associated with the internal combustion engine 20 based on one or more inputs received by one or more sensors 95 (and / or from sensors 35, 40). In various embodiments, at least one of the sensors 35, 40, or 95 may be assigned or divided to any different control system (e.g., OEM system 12, first fuel control system 14, second fuel control system 16) within the dual-fuel engine system 10 without changing the overall function of the sensor. For example, in various embodiments, the sensor 95 may be included in any of the following or operably coupled to any of the following: OEM system 12, first fuel control system 14, or second fuel control system 16. Similarly, the sensor 35 may be included in any of the following or operably coupled to any of the following: OEM system 12, first fuel control system 14, or second fuel control system 16. The sensor 40 may also be included within or operatively coupled to any of the following: the OEM system 12 , the first fuel control system 14 , or the second fuel control system 16 .

[0039] The second fuel control system 16 also includes an indicated engine power and a second fuel (e.g., gas, liquid, or second gas) power estimation module 115. The engine power and second fuel power estimation module 115 may include one or more processors configured to receive one or more inputs related to the operation of the dual-fuel engine system 10. The engine power and second fuel power estimation module 115 may also be configured to use a database 170 and / or a torque-to-power calculation system 175 to determine at least one of the following: a thermal efficiency estimate, a first power estimate of a second fuel (e.g., gas, liquid, or second gas), an indicated power estimate of a first fuel (e.g., diesel, first gas, or other liquid), a net engine power estimate, an intake manifold temperature (e.g., a maximum intake manifold temperature), and / or other related parameters. In various embodiments, the database 170 is a lookup table. In some embodiments, the torque-to-power calculation system 175 may be computer logic or include computer logic. In various embodiments, the engine power and second fuel power estimation module 115 is configured to receive one or more inputs corresponding to: a G / D estimate, a friction torque estimate, an accessory ("parasitic") torque estimate, a first fuel rate, an engine speed, an intake manifold temperature, and / or an MN estimate. In an embodiment, the KPI estimate is determined by the KPI module 125. Although the terms "torque" and "power" are used in various contexts throughout this disclosure, it should be understood that in various embodiments, torque may be used in place of power, or power may be used in place of torque. For example, it should be understood that power may be calculated based on torque and speed, and vice versa. In yet other embodiments, any other parameter indicative of load (e.g., alternatively or in addition to torque and / or power) may be determined and / or used in operations performed by the control system 11.

[0040] The second fuel control system 16 also includes a second fuel (e.g., gas, liquid, or second gas) LHV and G / D estimation module 120. The LHV and G / D estimation module 120 may include a second fuel (e.g., gas, liquid, or second gas) power selector switch 185, an LHV learning algorithm 180 configured to process one or more received inputs, and a power rationality diagnostic and protection module 190. In various embodiments, the LHV learning algorithm 180 includes a filter (e.g., a low pass filter, a moving average filter, etc.) and / or an adaptive learning routine. In some embodiments, one or more inputs are received from the sensor 95. The LHV and G / D estimation module 120 may include one or more processors configured to receive inputs including: a total flow estimate of the second fuel (i.e., the second fuel flowing within the engine system 10), a thermal efficiency estimate, an indicated power estimate of the first fuel, and a first indicated engine power estimate. In various embodiments, one or more processors of the LHV and G / D estimation module 120 may receive input from sensors 35, 40, and / or 95. The LHV and G / D estimation module 120 may thereby estimate the G / D amount and the LHV amount associated with the internal combustion engine 20. In various embodiments, one or more processors within the LHV and G / D estimation module 120 may determine the LHV and G / D estimates by multiplying the total flow estimate of the second fuel by the thermal efficiency estimate and using the result to normalize the first power estimate of the second fuel (e.g., by dividing the first power estimate of the second fuel by the product of the total flow estimate of the second fuel and the thermal efficiency estimate) to determine the instantaneous LHV amount. The LHV learning algorithm 180 may process the instantaneous LHV amount to then determine (i.e., learn) the LHV estimate. In various embodiments, the second fuel power selector switch 185 may be configured to receive input corresponding to the first power estimate and the second power estimate. In some embodiments, the second fuel power selector switch 185 may also be configured to output a final power estimate for the second fuel using the first power estimate and the second power estimate. In various embodiments, the final power estimate for the second fuel is based on a maximum or minimum of the first power estimate and the second power estimate. In various embodiments, the power rationality diagnostic and protection module 190 may include one or more processors configured to receive inputs corresponding to the first indicated engine power estimate and the second indicated engine power estimate. In some embodiments, the power rationality diagnostic and protection module 190 is further configured to initiate one or more diagnostic operations or engine protection protocols based on and in response to a comparison of one or both of the first indicated engine power estimate and the second indicated engine power estimate with one or more thresholds.

[0041] As shown, the second fuel control system 16 also includes a G / D target automatic compensation module 105. In various embodiments, the G / D target automatic compensation module 105 is configured to adjust or compensate the G / D target of the internal combustion engine 20. The module 105 is configured to receive one or more inputs indicating engine speed, engine load (e.g., power, torque, etc.), intake manifold temperature, and / or KPI estimates. In various embodiments, the module 105 receives one or more inputs from sensors 95, 35, and / or 40. In some embodiments, the one or more inputs received by the module 105 are processed by a speed-based G / D target interpolation unit 135 to determine the G / D target based on the indicated engine speed. In various embodiments, the speed-based G / D target interpolation unit 135 uses data stored in one or more databases 145 to determine the G / D target based on the indicated engine speed. In some embodiments, the one or more databases 145 may include one or more lookup tables. Module 105 also includes a G / D target limiter 140, which includes one or more processors configured to determine a G / D target limit value based on one or more inputs. In various embodiments, the one or more inputs may include engine knock, exhaust temperature, and / or the first fuel amount. In various embodiments, the exhaust temperature corresponds to the exhaust temperature of the engine bank. The second fuel control system 16 may use the G / D target limit value and the first indicated engine power estimate value to determine a second fuel power target value.

[0042] like Figure 2 As shown, the second fuel control system 16 includes a second fuel injector control module 110, which includes at least one G / D proportional integral derivative (PID) controller 150. In various embodiments, the PID controller 150 is configured to receive a feedforward input, which is based on a second fuel flow target compensated by a second fuel injector pressure and temperature. In various embodiments, the second fuel injector pressure and temperature can be measured by sensors 95, 35 and / or 40. The controller 150 can also receive a feedback input corresponding to a G / D estimate and a target input corresponding to a G / D controller. In response to receiving the feedforward input, the feedback input and the target input, the PID controller 150 can output at least one basic second fuel injector command. In various embodiments, at least one basic second fuel injector command is associated with at least one engine group second fuel injector command. In some embodiments, at least one engine group second fuel injector command includes a left group second fuel injector command and / or a right group second fuel injector command.

[0043] The second fuel injector command converter 160 can be operably coupled to the PID controller 150. In various embodiments, the second fuel injector command converter 160 can include one or more processors configured to convert the basic second fuel injector command into at least one engine group second fuel injector command. The second fuel injector control module 110 can also include a group balancing PID controller 155. In various embodiments, the PID controller 155 is configured to receive feedback inputs corresponding to the following items: the exhaust temperature difference between the left group (e.g., left group 30) of the internal combustion engine 20 and the right group (e.g., right group 31) of the internal combustion engine 20, and the target value associated with the exhaust temperature difference. In various embodiments, the target value is zero. In response to the feedback input and the target input, the PID controller 155 is configured to output a left group correction amount and a right group correction amount. In various embodiments, one or both of the left group correction amount and the right group correction amount can be a positive value or a negative value. The output left group correction amount and right group correction amount can each be added to the basic second fuel injector command (e.g., the output from the PID controller 150), and the second fuel injector command converter 160 can convert it into the corresponding left group second fuel injector command and right group second fuel injector command. The second fuel flow estimator 165 is configured to receive each of the left group second fuel injector command and the right group second fuel injector command as well as the second fuel pressure and the second fuel temperature. In various embodiments, the second fuel flow estimator 165 may include or be coupled to one or more processors within the module 110. In some embodiments, the second fuel pressure and / or the second fuel temperature are measured by sensors 95, 35 and / or 40. In various embodiments, the second fuel flow estimator 165 is configured to output a total second fuel flow estimate associated with the internal combustion engine 20 based on the left group second fuel injector command and the right group second fuel injector command, the second fuel pressure, and the second fuel temperature.

[0044] Finally, if Figure 2As shown, the second fuel control system 16 includes a second fuel heater control module 100. In various embodiments, the second fuel heater control module 100 is configured to control the operating state of at least one heater 32 coupled to the internal combustion engine 20. In various embodiments, the second fuel heater control module 100 includes one or more processors configured to receive one or more inputs from at least one controller 18 and / or from other components within the control system 11. The one or more processors within the second fuel heater control module 100 can be configured to cause the second fuel heater control module 100 to change the operating state of at least one heater 32. In some embodiments, changing the operating state of at least one heater 32 can include adjusting the operating setting of the heater control valve 195 to control the operating state of at least one heater 32. In various embodiments, at least one heater 32 can be an electric heater. In other embodiments, at least one heater 32 can be configured to use engine coolant to provide heat.

[0045] In various implementations, the engine control system 11 including the OEM system 12 , the first fuel control system 14 , and the second fuel control system 16 may cooperate to control the dual fuel engine system 10 . Figure 3 A flow chart is shown that illustrates a method 300 for controlling a dual fuel engine system 10 according to an exemplary embodiment. In operation 305, the engine control system 11 estimates the total engine load (e.g., power, torque, etc.) of the internal combustion engine 20. In various embodiments, the OEM system 12 calculates the total engine load by determining a first load amount ("primary load") transmitted through the engine (e.g., via a flywheel, a frac pump load, etc.) and broadcasting the determined first load amount (e.g., via a data link) to the first fuel control system 14 and / or the second fuel control system 16. In embodiments where the OEM system 12 controls an accessory load ("secondary load", such as a cooling fan load) within the dual fuel engine system 10, the OEM system 12 may estimate the accessory load, add the accessory load to the first load amount, and then broadcast the sum indicating the total engine load to the system 14 and / or 16 (e.g., via a data link). In operation 310, the control system 11 may determine the total fuel charge of the internal combustion engine 20. The control system 11 may then control the dual fuel engine system 10 in operation 315 using the total fuel charge determined in operation 310 .

[0046] In various implementations, the control system 11 may estimate the total engine load (e.g., power, torque, etc.). In some implementations, the control system 11 estimates the total engine load in operation 305 by measuring engine power in operation 320, estimating power loss in operation 325, and determining the sum of the measured engine power and the estimated power loss in operation 330. In some embodiments, the estimated total engine load may be based on input received from the OEM system 12 (e.g., from one or more sensors that may sense at least one of pump discharge pressure, speed, current, or voltage) in response to an external load or indicative of an external load. The OEM system 12 may then use the input (i.e., the sensed information) to calculate the engine load. The OEM system 12 may then output the calculated load value to the second fuel control system 16 and / or the first fuel control system 14 using a data link signal and / or an analog signal (e.g., 4 mA-20 mA). In some embodiments, the external load corresponds to at least one of a generator or a pump operably coupled to the internal combustion engine 20. In various implementations, the engine control system 11 may determine the total fuel fill in operation 310. In some implementations, the control system 11 determines the total fueling amount in operation 310 based at least in part on the measured engine speed 335 and the calculated governor indicated torque demand 340. Figure 4 As shown, in various implementations, controlling the dual fuel engine system 10 in operation 315 may include determining an updated total fuel fill amount in operation 345, and determining at least one control input for at least one actuator 33 in operation 350. In various embodiments, the at least one actuator 33 may be a first fuel system actuator. In various implementations, the updated total fuel fill amount determined in operation 345 may be based on determining the operating state of the dual fuel mode switch 55 in operation 355. In various embodiments, the updated fuel fill amount determined in operation 345 includes a first updated fuel fill amount and a second updated fuel fill amount. In some embodiments, the first updated fuel fill amount corresponds to a maximum value between the total fuel fill amount and a fuel command for a first fuel (e.g., diesel, a first gas, or other liquid). In some embodiments, the second updated total fuel fill is determined by subtracting the fuel command for the first fuel from the first updated total fuel fill to determine a first fuel equivalent of the fuel fill for the second fuel, and adding the first fuel equivalent fuel fill to the second fuel command for the first fuel.

[0047] In various implementations, determining the control input for at least one actuator 33 (in operation 350) may be based on selecting a set of lookup tables. Information in the lookup tables may then be referenced when determining the control input. The lookup tables may contain information from one or more of: the first fuel ECM and torque fueling calculation module 45, the first fuel air handling, aftertreatment and fuel system reference determination and control module 60 and / or the indicated engine power and the second fuel power estimation module 115. The selection of the set of lookup tables may be performed in operation 360. In various embodiments, selecting the set of lookup tables in operation 360 includes determining a compressor inlet density (CID) of the internal combustion engine 20. In some embodiments, selecting the set of lookup tables in operation 360 additionally or alternatively includes determining a G / D within the internal combustion engine 20. In other embodiments, selecting the set of lookup tables in operation 360 additionally or alternatively includes determining an operating state of the dual fuel mode switch 55. In some embodiments, selecting the set of lookup tables in operation 360 includes selecting at least one of an air handling reference table, an aftertreatment reference table, or a fueling reference table.

[0048] In various implementations, the control system 11 may determine a maximum amount between the total fuel fill (from operation 310) and the first fuel command for the first fuel. In various embodiments, the first fuel command for the first fuel is determined from the first fuel control system 14. In some embodiments, the control system 11 may be configured to determine a second updated total fuel fill. In various embodiments, the second updated total fuel fill is determined by subtracting the first fuel command for the first fuel from the first updated total fuel fill to determine a first fuel equivalent of a fuel fill of a second fuel associated with the internal combustion engine, and adding the first fuel equivalent of the fuel fill of the second fuel to the second fuel command for the first fuel. In various embodiments, the control system 11 may determine at least one actuator command based on the engine speed and at least one of the first updated total fuel fill or the second updated total fuel fill. In some embodiments, the at least one actuator command may be associated with at least one actuator within the air handling control system 80, the aftertreatment control system 85, the first fuel control system 90, or the actuator 33.

[0049] In various embodiments, determining the total fueling amount in operation 310 may include referencing one or more torque-fuel lookup tables. In various embodiments, one or more torque-fuel lookup tables are determined or referenced from the first fuel ECM and the torque fueling calculation module 45. In various embodiments, the lookup table may be based on the engine speed and the indicated first fuel torque input. In some embodiments, the indicated first fuel torque input may be determined by sensor 35. In various embodiments, the indicated first fuel torque input determined in operation 310 is based on the sum of the friction power estimate and the engine speed torque demand. In some embodiments, the engine speed torque demand corresponds to the difference between the engine speed and the predetermined engine speed target. In various embodiments, the control system 11 determines the power loss estimate in operation 325. In some embodiments, the control system 11 determines the power loss estimate in operation 325 by estimating the amount of friction torque associated with the internal combustion engine 20, estimating the amount of accessory torque, determining the amount of charge air pumping torque, and determining the engine speed. In various embodiments, the engine speed is determined via sensors 35, 40, and / or 95. In various embodiments, the charge air pumping torque amount is an estimate of pumping losses associated with the dual fuel engine system 10, where the pumping losses correspond to the amount of work done by the engine to draw air into the engine to facilitate combustion and then exhaust the combustion products to the atmosphere. In some embodiments, the charge air pumping torque may be measured using cylinder pressure data determined during engine development. In various embodiments, the data determined during engine development may be used to calibrate a pumping torque virtual sensor (i.e., operably coupled to the OEM system 12, the first fuel control system 14, and / or the second fuel control system 16) configured to sense the charge air pumping torque amount.

[0050] In some implementations, the friction torque estimate can be determined from a lookup table. In various embodiments, the lookup table is determined or referenced from the first fuel ECM and the torque fuel filling calculation module 45. In some embodiments, the lookup table is based on the engine speed and the engine friction parameter. In some embodiments, the engine friction parameter can correspond to the oil temperature or coolant temperature within the internal combustion engine 20 of the dual-fuel engine system 10. In various embodiments, the control system 11 can be configured to determine the accessory torque estimate from the lookup table. In various embodiments, the lookup table is determined or referenced from the first fuel ECM and the torque fuel filling calculation module 45. In some embodiments, the lookup table is based on the engine speed and the accessory torque parameter. In various embodiments, the accessory torque parameter can correspond to the cooling fan power amount (e.g., measured value or estimated value) or duty cycle commanded by the internal combustion engine 20 of the dual-fuel engine system 10.

[0051] In various embodiments, the control system 11 is configured to determine the first fuel command for the first fuel from a torque-fuel lookup table. In various embodiments, the torque-fuel lookup table is determined or referenced from the first fuel ECM and the torque fueling calculation module 45. In some embodiments, the torque-fuel lookup table is based on the engine speed (i.e., of the internal combustion engine 20) and the sum of the friction power estimate and the torque demand associated with the internal combustion engine 20. In various implementations, the torque demand is set by the engine speed governor 50.

[0052] In various embodiments, the control system 11 may be configured to activate one or more protective measures associated with the internal combustion engine 20. In some embodiments, the control system 11 is configured to activate one or more protective measures via the power rationality diagnostic and protection module 190. Figure 5 A method 400 is shown that may be implemented by the control system 11 to activate one or more engine protection measures. In operation 405, the control system 11 is configured to determine an amount of friction power loss. In various implementations, the amount of friction power loss may be determined by measuring the speed of the internal combustion engine 20 in operation 425 and estimating the amount of friction torque in operation 430. After determining the amount of friction power loss in operation 405, the control system 11 may determine an amount of accessory power loss in operation 410. In various embodiments, the amount of accessory power loss may be associated with a load applied by the OEM system 12 (e.g., one or more cooling fans, pumps, alternators, etc.) and / or any other accessory components within or coupled to the internal combustion engine 20.

[0053] In various embodiments, the amount of accessory power loss may be based on the measured engine speed (determined in operation 425) and based on the estimated amount of accessory torque determined in operation 435. Using the amount of accessory power loss and the amount of friction power loss, the control system 11 may estimate the amount of net engine power in operation 415. In various embodiments, the amount of net engine power may also be based on the amount of brake power (e.g., engine dynamometer measurements) determined by the control system 11 in operation 440. Using the estimated amount of net engine power determined in operation 415, the control system 11 may estimate the first indicated engine power and the first power amount for the second fuel in operation 420. In various embodiments, the control system 11 may also estimate the indicated first fuel power. In some embodiments, the control system 11 is configured to estimate the indicated first fuel power by multiplying the determined thermal efficiency correction amount by the determined first fuel power estimate.

[0054] In some embodiments, determining the first fuel power estimate includes using a first lookup table. In various embodiments, the first lookup table is determined or referenced from the first fuel ECM and torque fueling calculation module 45. In some embodiments, the first lookup table is based on the first fuel rate and the engine speed. In various embodiments, determining the thermal efficiency correction includes referencing a first set of lookup tables. In some embodiments, the first set of lookup tables is determined or referenced from the first fuel ECM and torque fueling calculation module 45. In various embodiments, the first set of lookup tables is based on the G / D of the internal combustion engine 20, the KPI associated with the internal combustion engine 20, and / or the intake manifold temperature within the internal combustion engine 20. In various embodiments, estimating the first power amount for the second fuel includes subtracting the indicated first fuel power from the indicated engine power.

[0055] Then, in operation 450, the control system 11 may estimate a second indicated engine power and a second power amount for the second fuel. In various embodiments, the second total indicated engine power and the second power amount of the second fuel may be based at least in part on the second fuel LHV value determined in operation 445. In various embodiments, the LHV determined in operation 445 may be based on the first power amount of the second fuel (determined in operation 420), the total second fuel flow estimate, and the thermal efficiency correction amount. In some implementations, the LHV may be determined by an estimate. In various embodiments, the control system 11 may determine the LHV estimate by dividing the first power amount of the second fuel by a multiple of the second fuel flow estimate and the thermal efficiency correction amount. In various implementations, the resulting LHV is an instantaneous LHV amount. In some embodiments, the control system 11 may be configured to implement a learning algorithm to determine the LHV estimate based on the instantaneous LHV amount.

[0056] In other embodiments, the second total indicated engine power and the second power amount of the second fuel may be additionally or alternatively based on the estimated engine second fuel flow (determined in operation 453) and the estimated first fuel power amount (determined in operation 455). In various embodiments, determining the second total indicated engine power includes determining the product of the total second fuel flow estimate and the LHV estimate, and adding the product of the total second fuel flow estimate and the LHV estimate to the first fuel power estimate. In some embodiments, the control system 11 may be configured to determine the first power estimate of the second fuel based on the first total indicated engine power, and determine the second power estimate of the second fuel based on the LHV estimate and the product of the thermal efficiency parameter and the estimated engine second fuel flow. In various embodiments, the thermal efficiency parameter corresponds to the thermal efficiency correction amount. Then, the control system 11 may determine the final second fuel power estimate based on the first power estimate and the second power estimate of the second fuel. In various embodiments, the control system 11 may be configured to estimate the G / D of the internal combustion engine 20. In various embodiments, the control system 11 is configured to estimate the G / D of the internal combustion engine 20 by dividing the final second fuel power estimate by the first total engine power estimate.

[0057] like Figure 5 As shown, in operation 460, the control system 11 may then calculate the difference between the first total indicated engine load (e.g., power, torque, etc.) (determined in operation 420) and the second total indicated engine load (e.g., power, torque, etc.) (determined in operation 450). Then, in operation 465, the control system 11 may compare the difference between the first total indicated engine load (calculated in operation 460) and the second total indicated engine load to a predetermined threshold. For example, in various implementations, the control system 11 may determine the difference between the predetermined threshold and the difference between the first total indicated engine load and the second total indicated engine load (i.e., the total indicated engine load delta). In various embodiments, the predetermined threshold may be set by the OEM and / or user of the dual fuel engine system 10.

[0058] Therefore, if the difference between the total indicated engine load increment and the predetermined threshold is greater than a predetermined amount, the control system 11 can determine that the dual fuel engine system 10 is operating under abnormal or adverse conditions. In various embodiments, the predetermined threshold is associated with a predetermined time period. In various embodiments, the predetermined threshold can be set, such as by the controller 18. For example, if the difference between the total indicated engine load increment and the predetermined threshold is greater than a predetermined amount within a predetermined time period, the control system 11 can determine that the dual fuel engine system 10 is operating in an abnormal or adverse state. Therefore, in response to the control system 11 determining that the difference between the first total indicated engine load and the second total indicated engine load meets the predetermined threshold (or the total indicated engine load increment exceeds the predetermined amount), the control system 11 can activate one or more engine protection measures 470. For example, the control system 11 can disable dual fuel operation, perform a shutdown and / or reduce the engine speed, etc.

[0059] In other embodiments, control system 11 may be configured to determine one or more secondary fuel power targets associated with internal combustion engine 20 . Figure 6 A method 500 for determining a second fuel power target associated with an internal combustion engine 20 is shown. The control system 11 measures the engine speed in operation 505 and estimates the amount of engine power in operation 510. In various embodiments, the engine speed is sensed by sensors 95, 35 and / or 40. In some embodiments, the amount of engine power is a net engine power amount. In operation 515, the control system 11 may calculate a percentage of the rated power ("percent power") of the internal combustion engine 20 based on the estimated engine power from operation 510. The percent rated power may be calculated by dividing the net engine power by the rated engine power limit and multiplying by 100%. The control system may also determine an intake manifold temperature (e.g., a maximum intake manifold temperature) in operation 525 and determine an estimated value of the KPI for the second fuel in operation 530.

[0060] In various embodiments, the control system 11 may determine a base second fuel substitution rate (G / D) target for the internal combustion engine 20 in operation 520. In various embodiments, the control system 11 determines the base G / D target based on the engine speed, percent rated power, intake manifold temperature (determined in operation 525), and estimated KPIs of the internal combustion engine 20. Then, in operation 535, the control system 11 determines a second fuel power target for the internal combustion engine 20 based on the base second fuel substitution rate target determined in operation 520. In various embodiments, the second fuel power target is based on the base G / D target and a first indicated engine power estimate. In some embodiments, the control system 11 determines the first indicated engine power estimate by performing operation 420 of method 400. In various embodiments, the control system 11 is configured to determine (e.g., calculate) the first indicated engine power based on an estimated amount of engine power and an amount of friction power loss.

[0061] In various embodiments, the base G / D target determined in operation 520 is based on a first speed base G / D target when the engine speed is above a threshold value (which may be determined in operation 540) and a speed base G / D target when the engine speed is below a threshold value (which may be determined in operation 545). In various embodiments, at least one of the first speed base G / D target or the second speed base G / D target is determined based on the intake manifold temperature (determined in operation 525) and / or an estimated KPI (such as methane number) (determined in operation 530). In various embodiments, the first speed base G / D target is a high speed base G / D target, and the second speed base G / D target is a low speed base G / D target (i.e., lower than the first base G / D target). In some embodiments, the high speed base G / D target is based on a percentage of rated power, an intake manifold temperature, and a KPI estimate. Similarly, the low speed base G / D target is based on a percentage of rated power, an intake air temperature, and a KPI estimate. Therefore, the base G / D target determined in operation 520 is further determined by interpolation between the high speed base G / D target and the low speed base G / D target based on engine speed. In various embodiments, the high speed base G / D target is determined from a first set of lookup tables and the low speed base G / D target is determined from a second set of lookup tables (i.e., from the lookup tables / database 145).

[0062] In various embodiments, the control system 11 may be configured to operate the dual fuel engine system 10 to determine one or more secondary fuel injector commands for at least one engine bank within the internal combustion engine 20 . Figure 7A method 600 for determining at least one second fuel injector command for at least one engine bank within the internal combustion engine 20 is shown. In operation 605, the control system 11 is configured to determine a second fuel flow target. In various implementations, the second fuel flow target is based on the second fuel power target determined in operation 625, the thermal efficiency estimate determined in operation 630, and the LHV determined in operation 635. In some implementations, the second fuel power target determined in operation 625 is determined by the control system 11 via the method 500. In other implementations, the LHV determined in operation 635 is determined via the control system 11 performing one or more operations similar or equivalent to operation 445. In other embodiments, the LHV determined in operation 635 is determined via an LHV sensor or a lookup table based on a measured or estimated KPI. In various embodiments, determining the second fuel flow target in operation 605 includes dividing the second fuel power target by the thermal efficiency estimate and the LHV.

[0063] The control system 11 is configured to adjust the second fuel flow target in operation 610 based on at least one of the measured second fuel temperature determined in operation 640 and / or the second fuel injector pressure measured in operation 645. In various embodiments, at least one of the second fuel temperature or the second fuel injector pressure is measured by sensors 35, 40, and / or 95. Using the adjusted second fuel flow target determined in operation 610, the control system 11 is configured to determine at least one base second fuel injector command in operation 615. In various embodiments, the at least one base second fuel injector command is also determined based on the estimated G / D of the internal combustion engine 20 determined in operation 650 and the G / D target determined in operation 655. In various implementations, the G / D target determined in operation 655 is determined by the control system 11 by implementing one or more operations similar or equivalent to operation 520. Then, in operation 620, the control system 11 may determine at least one second fuel injector command for at least one engine bank of the internal combustion engine 20. In some embodiments, the second fuel power target is based on the first indicated engine power estimate and the G / D target. In various implementations, the first indicated engine power estimate is determined by the control system 11 by performing operation 420. In some implementations, adjusting the second fuel flow target in operation 610 includes calculating an adjusted second fuel flow target amount. In various embodiments, the second fuel flow target amount is based on a product of the second fuel flow target and at least one of: a first ratio of a measured second fuel temperature to a temperature reference amount, or a second ratio of a measured second fuel injector pressure to a pressure reference amount.

[0064] In various implementations, the control system 11 may also be configured to estimate the total second fuel flow. In various embodiments, the estimated total second fuel flow is based on the measured second fuel injector pressure (determined in operation 645), the measured second fuel temperature (determined in operation 640), and at least one second fuel injector command for at least one engine group. In some implementations, the at least one second fuel injector command for at least one engine group includes a left group second fuel injector command (i.e., for the left group 30) and a right group second fuel injector command (i.e., for the right group 31). In other implementations, determining the left group second fuel injector command and determining the right group second fuel injector command include: biasing the at least one second fuel injector command for at least one engine group to each of the left group 30 and the right group 31.

[0065] In various embodiments, biasing at least one second fuel injector command for at least one engine bank to each of the left bank 30 and the right bank 31 is based on an exhaust temperature difference associated with each of the left bank 30 and the right bank 31. In some embodiments, the exhaust temperature difference is measured by sensors 35, 40, and / or 95. In other embodiments, the exhaust temperature difference corresponds to the difference between the exhaust temperature measured at the left bank 30 and the exhaust temperature measured at the right bank 31. Therefore, during operation of the dual-fuel engine system 10, the control system 11 can measure the exhaust temperature of the left bank 30, measure the exhaust temperature of the right bank 31, and determine the difference between the exhaust temperature of the left bank 30 and the exhaust temperature of the right bank 31. Then, the control system 11 can add the left bank adjustment amount to at least one second fuel injector command for at least one engine bank. In various embodiments, the control system 11 adds the left bank adjustment amount to the at least one second fuel injector command to determine a first adjusted basic second fuel injector command based on the difference between the left bank exhaust temperature and the right bank exhaust temperature. Similarly, the control system 11 can then add the right bank adjustment amount to at least one second fuel injector command for at least one engine bank. In various embodiments, the control system 11 adds the right group adjustment amount to at least one injector command for the second fuel to determine a second adjusted base second fuel injector command based on the difference between the left group exhaust temperature and the right group exhaust temperature. The control system 11 can then convert each of the first adjusted base second fuel injector command and the second adjusted base second fuel injector command into a left group second fuel injector command and a right group second fuel injector command, respectively.

[0066] In some implementations, determining at least one second fuel injector command for at least one engine bank in operation 615 includes determining a feedforward input for a G / D PID controller operably coupled to the internal combustion engine 20. In various embodiments, the G / D PID controller is the controller 150. In some embodiments, the feedforward input is based on a lookup table. In various embodiments, the lookup table is determined or referenced from the first fuel ECM and torque fueling calculation module 45, the first fuel air treatment, aftertreatment and fuel system reference determination and control module 60 and / or the indicated engine power and second fuel power estimation module 115. In various embodiments, the lookup table is based on at least one of the following: a measured second fuel injector pressure, a measured second fuel temperature, or an adjusted second fuel flow target amount. In some embodiments, the control system 11 is also configured to determine at least one thermal control valve command. In various embodiments, the at least one thermal control valve command is associated with the heater control valve 195. In some embodiments, the at least one thermal control valve command is based on a measured second fuel temperature and / or a measured second fuel mass flow rate within the internal combustion engine 20. In yet other embodiments, the control system 11 is further configured to adjust at least one second fuel temperature set point based on a measured KPI and / or an estimated KPI number. In various embodiments, the measured KPI is measured by sensors 35, 40, and / or 95. In some embodiments, the estimated KPI number is determined by the KPI estimation module 125. In some implementations, at least one second fuel temperature set point is based on an engine protection set point. In various embodiments, the engine protection set point is determined or set by the OEM system 12, the first fuel control system 14, or the second fuel control system 16.

[0067] Figure 8A method 700 performed by a dual fuel engine system 10 is shown. In various embodiments, the dual fuel engine system 10 includes at least one PID controller coupled to the internal combustion engine 20 and the second fuel injector 28. In operation 705, the control system 11 determines a G / D estimate. In various embodiments, the G / D estimate is determined from the LHV and G / D estimation module 120. Then, the control system 11 determines a G / D target in operation 710. In various embodiments, in operation 710, the control system 11 determines the G / D target by performing one or more operations similar or equivalent to operation 520 in method 500. In operation 715, at least one PID controller is configured to receive feedforward input in addition to the G / D estimate and the G / D target. In various embodiments, the feedforward input is based on a lookup table that can be determined or referenced from: the first fuel ECM and torque fueling calculation module 45, the first fuel air treatment, aftertreatment and fuel system reference determination and control module 60 and / or the indicated engine power and the second fuel power estimation module 115.

[0068] In some embodiments, the G / D target is determined from the LHV and G / D estimation module 120. In operation 720, at least one PID controller is configured to output at least one second fuel injector command. In operation 725, at least one PID controller then biases at least one second fuel injector command to each of the left group 30 and the right group 31. In various embodiments, at least one PID controller biases at least one second fuel injector command to each of the left group 30 and the right group 31 based on the difference between each of the left group exhaust temperature (determined in operation 730) and the right group exhaust temperature (determined in operation 735). In various embodiments, the exhaust temperature difference is determined in operation 740. In some embodiments, at least one PID controller includes a first PID controller and a second PID controller. For example, the first PID controller can be configured to receive a feedforward input, a G / D estimate, and a G / D target (ie, the PID controller 150), and the second PID controller can be configured to bias at least one second fuel injector command to each of the left group 30 and the right group 31 (ie, the group balancing PID controller 155).

[0069] In some embodiments, the dual fuel engine system 10 includes an aftertreatment system operably coupled to the internal combustion engine 20 (i.e., controlled by the aftertreatment control system 85), a second fuel injection system including at least one second fuel injector 28 (i.e., controlled by the second fuel injector control module 110), and an air handling system operably coupled to the internal combustion engine 20 (i.e., controlled by the air handling control system 80). In some implementations, the aftertreatment system is a selective catalytic reduction (SCR) and oxidation catalyst (OC) system. In some embodiments, the second fuel injection system is configured to independently control the second fuel injection on each of the left group 30 and the right group 31 (i.e., via at least one second fuel injector 28). In other embodiments, the air handling system is configured to control the air flow through the internal combustion engine 20. In some embodiments, the air handling system controls the air flow independently of the operating conditions of the internal combustion engine 20. In other embodiments, the air flow is based on a predetermined value obtained from a lookup table. In various embodiments, the lookup table is determined by or corresponds to a database 75 in the module 60. In various embodiments, the predetermined value is associated with a target temperature in at least one position of the aftertreatment system.

[0070] In various embodiments, the dual fuel engine system 10 includes one or more heaters operably coupled to at least one second fuel injector 28 and the internal combustion engine 20. The at least one heater is configured to adjust the temperature of the second fuel flowing within the internal combustion engine 20 (ie, heat it). Fig. 9A method 800 for controlling an operating state of a heater coupled to an internal combustion engine 20 is shown. In operation 805, the control system 11 is configured to determine a second fuel flow target. For example, the control system 11 is configured to determine the second fuel flow target via one or more operations similar or equivalent to operation 605. In various implementations, the second fuel flow target determined in operation 805 may be based on one or more of a second fuel power target, an estimated thermal efficiency, and an LHV. For example, the second fuel flow target may be based on the second fuel power target determined in operation 820, the estimated thermal efficiency of the internal combustion engine 20 determined in operation 825, and the LHV determined in operation 830. In operation 810, the control system 11 may adjust the second fuel flow target based on at least one of a measured second fuel temperature or a measured second fuel injector pressure. For example, in operation 810, the control system 11 is configured to adjust the second fuel flow target based on at least one of a measured second fuel temperature determined in operation 835 or a measured second fuel injector pressure determined in operation 840. In various implementations, the measured second fuel temperature determined in operation 835 is determined by the control system 11 by performing one or more operations similar or equivalent to operation 640. In some embodiments, the measured second fuel temperature is determined via sensors 35, 40, and / or 95. In various embodiments, the measured second fuel injector pressure determined in operation 840 is determined by the control system 11 by performing one or more operations similar or equivalent to operation 645. In some embodiments, the measured second fuel injector pressure is determined via sensors 35, 40, and / or 95. The control system 11 may then control the operating state of the heater 32 in operation 815 based on at least one of the measured second fuel temperature or the measured engine coolant temperature (determined in operation 845). In some embodiments, at least one of the measured second fuel temperature or the measured engine coolant temperature is determined via sensors 35, 40, and / or 95.

[0071] In some embodiments, the control system 11 is configured to perform on / off control of the heater 32 in response to a determination made about the measured second fuel temperature relative to one or more threshold temperatures. For example, the control system 11 is configured to control the operation of the heater 32 in response to determining that the measured second fuel temperature is less than the first threshold temperature within a first period of time. Specifically, in some embodiments, the control system 11 is configured to operate (i.e., turn on) the heater 32 in response to determining that the measured second fuel temperature (determined in operation 835) is less than the first threshold temperature within the first period of time. In various embodiments, the first threshold temperature is set by the OEM system 12, the first fuel control system 14, or the second fuel control system 16. In other embodiments, the control system 11 is configured to control the operation of the heater 32 in response to determining that the measured second fuel temperature is greater than the second threshold temperature within a second period of time. For example, the control system 11 is configured to operate (i.e., turn off) the heater 32 in response to determining that the measured second fuel temperature (determined in operation 835) is greater than the second threshold temperature within the second period of time. In various embodiments, the second threshold temperature is set by the OEM system 12, the first fuel control system 14, or the second fuel control system 16.

[0072] According to one or more properties of the dual-fuel engine system 10, one or more injectors configured to provide fuel to the internal combustion engine may present at least one changed state. For example, one or more properties may include, but are not limited to, the age of the dual-fuel engine system 10 and / or the use application of the dual-fuel engine system 10. The changed state may be manifested as, for example, degradation of one or more components. The changed state may alternatively or additionally be manifested as a changed performance, such as drift with respect to the injector (e.g., drifting up or drifting down to inject more or less fuel, respectively). Therefore, in some embodiments, according to the age and use application of the dual-fuel engine system 10, an injector configured to provide a certain amount of the first fuel (or the second fuel) to the internal combustion engine 20 may degrade or drift over time. The changed state may affect the accuracy of one or more of the above-mentioned fuel-related estimates. For example, the changed state may impair the accuracy of the first fuel power estimate (e.g., as determined in operation 420) and / or the indicated first fuel power estimate. In some embodiments, the indicated first fuel power may be estimated (e.g., by the control system 11) from one or more reference repositories. The one or more reference repositories may be, for example, one or more lookup tables or one or more databases, etc. The one or more reference repositories may be stored, for example, in any one or more of the following: a memory within the controller 18, a memory within the OEM system 12, a memory within the first fuel control system 14, or a memory within the second fuel control system 16.

[0073] In various embodiments, the control system 11 can be configured to determine a drift amount corresponding to at least one of an injector for a first fuel (i.e., a first fuel injector) within the first fuel control system 14 or an injector for a second fuel (i.e., a second fuel injector) within the second fuel control system 16. Fig.10 A method 900 is shown that may be performed by the control system 11 to determine an amount of drift corresponding to a first fuel injector or a second fuel injector.

[0074] In operation 905, the control system 11 may operate the engine 20 in a mode using only the first fuel. While operating the engine 20 using the first fuel, the control system 11 may be configured to determine the current load on the engine 20 in operation 910. Then, in operation 915, the control system 11 may send at least one first signal to the first fuel control system 14. The first signal may cause the first fuel control system 14 to deliver a certain amount of the first fuel to the engine 20. In various embodiments, the first signal may include an electrical signal, a hydraulic parameter, a mechanical adjustment, or any other suitable signal known in the art.

[0075] After the control system 11 has sent the first signal and the first fuel control system 14 has delivered a quantity of the first fuel to the engine 20, the control system 11 may be configured to determine at least one first operating parameter associated with the engine 20 in operation 920. In various embodiments, the at least one first operating parameter may include engine speed, coolant temperature, oil temperature, coolant pressure, oil pressure, intake manifold pressure, intake manifold temperature, exhaust manifold temperature, exhaust manifold pressure, injection timing, and / or injection pressure.

[0076] Based on the first signal (i.e., the amount of the first fuel delivered), the current load measured in operation 910, and / or the at least one operating parameter determined in operation 920, the control system 11 may be configured to determine an engine load estimate associated with the engine 20 in operation 930. In various embodiments, the engine load estimate may be an indicative engine load. In operation 935, the control system 11 may be configured to compare the engine load estimate determined in operation 930 with the current load measured in operation 910.

[0077] Based on the comparison between the current load and the engine load estimate, the control system 11 may be configured to determine an adjusted engine load estimate in operation 940, wherein the adjusted engine load estimate corresponds to an amount of drift of the first fuel control system 14. Thus, the adjusted engine load estimate determined in operation 940 compensates for drift within the first fuel control system 14. For example, the adjusted engine load estimate compensates for drift of at least one first fuel injector within the first fuel control system 14. Once the control system 11 has determined the adjusted engine load estimate, the control system 11 may operate the engine 20 and the dual fuel engine system 10 using the adjusted engine load estimate in operation 945. By operating the dual fuel engine system 10 using the adjusted engine load estimate, the control system 11 may provide an appropriate amount of the first fuel (and / or the second fuel) in future engine cycles to account for drift in the first fuel control system 14 and reduce the risk of degradation of the dual fuel engine system 10.

[0078] In various embodiments, the control system 11 may be configured to determine an appropriate fueling amount of the second fuel based on determining an amount of drift corresponding to the first fuel control system 14. Fig.10 As shown, after operating the engine 20 using the adjusted engine load estimate determined in operation 945, the control system 11 may be configured to determine at least one second operating parameter associated with the engine 20 in operation 950. In various embodiments, the at least one second operating parameter may include engine speed, coolant temperature, oil temperature, coolant pressure, oil pressure, intake manifold pressure, intake manifold temperature, exhaust manifold temperature, exhaust manifold pressure, injection timing, and / or injection pressure. In various embodiments, the control system 11 may determine an amount of the second fuel to be delivered to the engine 20 in operation 955 based on the at least one second operating parameter determined in operation 950 and / or the comparison between the engine load estimate and the current load performed in operation 935.

[0079] In various embodiments, the control system 11 is configured to operate the engine 20 (and thus the dual fuel engine system 10) using the adjusted engine load estimate in operation 945 for a predetermined number of cycles or a predetermined period of time. Thus, in some embodiments, the control system 11 is configured to determine at least one second operating parameter in operation 950 during a predetermined number of cycles or a predetermined period of time. In various embodiments, the control system 11 is configured to determine the engine load estimate based on the net engine load. In some embodiments, the control system 11 is configured to determine the net engine load by estimating the total engine load and subtracting the parasitic load on the engine 20. In various embodiments, the control system 11 is configured to determine the parasitic load based on a load corresponding to one or more auxiliary components within the dual fuel engine system 10. For example, in some embodiments, the parasitic load on the engine 20 may correspond to an operating load of at least one cooling fan. Thus, in various embodiments, determining the parasitic load includes determining a load corresponding to at least one cooling fan.

[0080] It should be noted that the method 900 is described in the context of the control system 11 performing operations related to the first fuel and then performing operations related to the second fuel, and the control system 11 can be configured to perform the method 900 by first performing operations related to the second fuel and then performing operations related to the first fuel. For example, in some implementations, the control system 11 can be configured to first operate the engine 20 using the second fuel and determine the adjusted engine load estimate based on the second fuel. The control system 11 can then subsequently perform the method 900 to determine the amount of the first fuel to be delivered to the engine 20 based on the adjusted engine load estimate determined to compensate for drift in the second fuel control system 16.

[0081] In various embodiments, a method of controlling a dual-fuel engine 20 configured to receive a first fuel and a second fuel may include operating the engine 20 using the first fuel. The method may also include measuring, by a controller (e.g., controller 18), a current load of the engine 20. The method may also include sending, by a controller (e.g., controller 18), a first signal to a first fuel control system 14 to deliver an amount of the first fuel to the engine 20. The method may also include determining, by a controller (e.g., controller 18), at least one first operating parameter associated with the engine 20. The method may also include determining, by a controller (e.g., controller 18), an engine load estimate based on the first signal and the at least one first operating parameter. The method may include comparing, by a controller (e.g., controller 18), the engine load estimate with the measured load, and determining, by the controller, an adjusted engine load estimate based on the comparison to compensate for drift in the first fuel control system 14.

[0082] In other embodiments, the dual fuel engine system 10 may include: an engine 20 configured to receive a first fuel and a second fuel; a first fuel control system 14 for delivering the first fuel to the engine; a second fuel control system 16 for delivering the second fuel to the engine 20; and a controller 18 operably coupled to each of the engine 20, the first fuel control system 14, and the second fuel control system 16. The controller 18 may be configured to transmit a first signal to one of the first fuel control system 14 or the second fuel control system 16 to cause the first fuel control system 14 or the second fuel control system 16 to deliver a certain amount of the corresponding first fuel or second fuel. The controller 18 may be configured to measure a current engine load. The controller 18 may also be configured to determine at least one first operating parameter of the engine 20, and determine an engine load estimate based on the at least one first operating parameter and the amount of the first fuel or the second fuel. The controller 18 may be configured to compare the engine load estimate with the current engine load, and determine an adjusted engine load estimate based on the comparison to compensate for drift in one of the first fuel or the second fuel. In various embodiments, the controller 18 may be further configured to determine an amount of the other of the first fuel or the second fuel to be delivered to the engine 20. In some embodiments, the controller 18 is configured to determine an amount of the other of the first fuel or the second fuel based on at least one second operating parameter. In some embodiments, the dual fuel engine system 10 includes at least one generator configured to be driven by the engine 20, wherein the current engine load may be based on a current and / or voltage corresponding to the generator.

[0083] As described above, the control system 11 may be configured to determine the amount of drift corresponding to the first fuel control system 14 or the second fuel control system 16. In other embodiments, the control system 11 may be configured to control the drift in the first fuel control system 14 and / or the second fuel control system 16 by determining the fuel substitution rate G / D within the dual-fuel engine system 10. Therefore, in some embodiments, the control system 11 may be configured to determine the amount of drift by determining the substitution rate G / D. For example, if one or more first fuel injectors within the dual-fuel engine system 10 (e.g., within the first fuel control system 14) drift downward, the estimated indicated first fuel power may be higher than the actual indicated first fuel power. This difference may result in an underestimation of G / D. If G / D is underestimated, the internal combustion engine 20 may operate at a higher G / D than desired. Operating at a higher G / D exceeding a given threshold may result in one or more undesirable operating conditions. For example, undesirable operating conditions may include one or more of engine knock, increased component temperature (e.g., increased first fuel injector tip temperature), and / or other harmful effects that may affect various aspects of the dual-fuel engine system 10. These aspects may include overall performance, emission levels, reliability, and / or durability of the dual fuel engine system 10 .

[0084] Thus, in some embodiments, at least one of (i) the indicated engine power or the second fuel power estimation module 115 or (ii) the second fuel LHV and G / D estimation module 120 is configured to determine the G / D rate for the second fuel based on one or more properties of the dual-fuel engine system 10. In particular, at least one of (i) the indicated engine power or the second fuel power estimation module 115 or (ii) the second fuel LHV and G / D estimation module 120 is configured to determine the G / D rate for the second fuel based on the age of one or more injectors configured to provide a certain amount of the first fuel in the internal combustion engine 20. In various embodiments, the module 115 and / or the module 120 is configured to determine the G / D rate for the second fuel based on a virtual sensor. In some embodiments, the virtual sensor is configured to estimate the G / D based on the total indicated engine power and the indicated first fuel power. For example, the virtual sensor can estimate the G / D. For example, the virtual sensor can estimate the G / D by dividing the difference between the indicated first fuel power and the total indicated power by the total indicated power and multiplying to obtain the G / D. In particular, the virtual sensor may divide the difference between the indicated first fuel power and the total indicated power by the total indicated power and multiply the result by 100% to obtain G / D as a percentage substitution of the first fuel with the second fuel. This percentage substitution (fuel substitution percentage) may indicate the allocation between the first fuel and the second fuel. In this way, the fuel substitution rate of the dual-fuel engine system 10 may be determined. In various embodiments, the virtual sensor is included in the control system 11 or is in operative communication with the control system 11. For example, the virtual sensor may estimate G / D based on the total indicated engine power and the indicated first fuel power determined in operation 420.

[0085] Fig.11 1 is a flow chart illustrating a method 1000 executed by the control system 11 for estimating G / D within the dual fuel engine system 10. In particular, the method 1000 may be executed to estimate G / D using the indicated first fuel power determined in operation 1005. Fig.11 As shown, the control system 11 may be configured to determine the friction power or load on the engine 20 in operation 1030 and determine the parasitic power or load on the engine 20 in operation 1035. In various embodiments, the friction power may correspond to the braking power of the dual fuel engine system 10. In various embodiments, the parasitic load may correspond to the load of one or more auxiliary components (e.g., a cooling fan) within the dual fuel engine system 10.

[0086] The control system 11 may also be configured to determine an amount of engine power feedback associated with the engine 20 in operation 1040. Using the friction power, parasitic load, and / or the amount of engine power feedback, the control system 11 may determine an amount of total indicated power or total indicated load on the engine 20 in operation 1025. In various embodiments, the total indicated load may be a current load measured on the engine 20. In other embodiments, the total indicated load may be an estimate of the engine load determined by the control system 11.

[0087] To determine G / D, the control system 11 may be configured to determine an indicated power amount corresponding to each of the first fuel and the second fuel. Thus, the control system 11 may be configured to determine an indicated first fuel power in operation 1005. In various embodiments, the indicated first fuel power may be affected by one or more operating parameters within the dual fuel engine system 10. Thus, as Fig.11 As shown, the control system 11 may be configured to determine the adjusted first fuel power amount in operation 1010. The adjusted first fuel power amount may be based on an indicated thermal efficiency correction amount determined by the control system 11 in operation 1055. As shown, the thermal efficiency correction amount may be determined by the control system 11 based on at least one of the intake manifold temperature (which may be determined in operation 1050) or input from a fuel quality estimator (which may be obtained in operation 1045). In various embodiments, the intake manifold temperature may be a maximum temperature. In other embodiments, the intake manifold temperature may be an average temperature.

[0088] like Fig.11 As shown, in various embodiments, the control system 11 may be configured to determine an indicated second fuel power in operation 1015. In various embodiments, the indicated second fuel power may be determined by the control system 11 based on the adjusted indicated first fuel power determined in operation 1010 and / or the total indicated power determined in operation 1025. Using the indicated second fuel power and the total indicated power, the control system 11 may determine a compensated substitution rate G / D in operation 1020 that accounts for drift in at least one of the first fuel control system 14 or the second fuel control system 16.

[0089] In various embodiments, the control system 11 may be configured to determine the indicated first fuel power by compensating for drift and / or aging within the first fuel control system 14. After compensating for aging of one or more first fuel injectors, the control system 11 may then determine a compensated G / D. Fig.12 As shown, the control system 11 is configured to determine a total duration of operation of one or more of the internal combustion engine 20 and the fuel injectors. Fig.12A method 1100 is shown for determining an indicated first fuel power 1005 by taking into account the drift of at least one injector within the first fuel control system 14. Fig.11 As shown, the control system 11 may be configured to determine the engine operating time in engine hours in operation 1105. The total duration of operation may correspond to a total number of hours of operation of the internal combustion engine 20, for example.

[0090] The control system 11 is also configured to determine a total operation duration ("injector age") (e.g., total hours of operation) corresponding to the one or more first fuel injectors in operation 1115. Using the operation duration corresponding to the internal combustion engine 20 and each of the one or more first fuel injectors as input, the control system 11 may determine at least one injector age factor in operation 1130. In various embodiments, the control system 11 is configured to determine the at least one injector age factor from at least one first reference repository, such as one or more injector age reference repositories (e.g., one or more databases, one or more lookup tables, etc.).

[0091] Based on the determined injector age, the control system 11 is configured to determine a power correction associated with one or more first fuel injectors in operation 1150. Fig.12 As shown, the control system 11 is configured to determine the engine speed and the first fuel rate in operations 1110 and 1120, respectively (e.g., from the OEM system 12). Using the engine speed and the first fuel rate, the control system 11 is configured to determine the indicated first fuel power of the first injector in operation 1165. In various embodiments, the control system 11 is configured to determine the indicated first fuel power amount of the first injector by performing a fuel-power conversion in operation 1160. For example, the control system 11 can be configured to determine the indicated first fuel power amount of the first injector from at least one second reference repository, such as one or more first fuel injector fuel-power reference repositories (e.g., one or more databases, one or more lookup tables, etc.). In some embodiments, the indicated first fuel power amount of the first injector corresponds to the power amount associated with a nominal injector. The nominal injector can correspond to a substantially unused injector that has no or minimal service hours (e.g., at the beginning of its operating life).

[0092] The control system 11 may also be configured to determine an indicated first fuel power amount or an injector first fuel power correction amount ("end of life injector power correction amount") for the second injector in operation 1140. In various embodiments, the control system 11 may be configured to determine an end of life (EOL) power correction amount from at least one third reference repository. In some embodiments, the third reference repository may include one or more end of life (EOL) injector power correction tables corresponding to one or more first fuel injectors within the dual fuel engine system 10. In operation 1145, the control system 11 may use the EOL injector power correction amount to determine the EOL injector power amount.

[0093] In some embodiments, in addition to determining the indicated first fuel power amount and the injector first fuel power correction amount for the first injector, the control system 11 may also be configured to determine an age-fraction parameter associated with one or more first fuel injectors. In some embodiments, the age-fraction parameter is scaled based on the age of the one or more first fuel injectors. For example, the age-fraction parameter may be directly or indirectly proportional to the age of at least one first fuel injector. Thus, if Fig.11 As shown, the control system 11 can be configured to determine an age-based indicated first fuel power correction amount based on the indicated first fuel power amount of the first injector (determined in operation 1165), the injector first fuel power correction amount ("age factor") (determined in operation 1130), and the age score parameter.

[0094] In some embodiments, the control system 11 may determine the age-based indicated first fuel power correction amount by calculating one or more of the product of the indicated first fuel power amount of the first injector, the injector first fuel power correction amount, and the age fraction parameter in operation 1150. For example, the control system 11 may determine the age-based indicated first fuel power correction amount by calculating each of the product of the indicated first fuel power amount of the first injector, the injector first fuel power correction amount, and the age fraction parameter.

[0095] Finally, if Fig.12 As shown, the control system 11 may be configured to determine the indicated first fuel power amount in operation 1005 using the indicated first fuel power correction amount based on age (determined in operation 1150) and the indicated first fuel power amount of the first injector (determined in operation 1165). In various embodiments, determining the indicated first fuel power amount in operation 1005 may include subtracting the indicated first fuel power correction amount based on age (determined in operation 1150) from the indicated first fuel power amount of the first injector (determined in operation 1165). As previously described with respect to Fig.11 As described above, control system 11 may then determine G / D using the adjusted indicated first fuel power amount, indicated second fuel power amount, total indicated engine power, and thermal efficiency amount.

[0096] In other embodiments, Fig.13 As shown, the control system 11 may calculate at least one injector age factor using at least one age factor adaptive algorithm executing the method 1200. In various embodiments, operations 1210-1265 of the method 1200 are similar to or equivalent to corresponding operations 1110-1165 of the method 1100. Fig.13 As shown, in various embodiments, the control system 11 may perform at least one age factor adaptive algorithm in operation 1267 to determine a calibration amount ("correction factor"). In various embodiments, the control system 11 may perform operation 1267 by determining an upper calibration amount and / or a lower calibration amount. For example, the calibration amount may be a lower calibration amount (e.g., zero), which may correspond to no or minimum age-based indicated first fuel power correction amount. For example, in the case where one or more first fuel injectors are substantially unused (i.e., no or less than a threshold service hour), the lower calibration amount is zero. The lower calibration amount is zero or may correspond to an age-based indicated first fuel power correction amount of zero, i.e., no age-based first fuel power correction amount. The control system 11 may also be configured to determine an upper calibration amount, which may correspond to an EOL or maximum age-based indicated first fuel power correction amount. The control system 11 may be configured to adjust the age-based indicated first fuel power correction amount by interpolating between the lower calibration amount and the upper calibration amount in operation 1270 to determine the age correction factor.

[0097] In various embodiments, the control system 11 may be configured to interpolate between the lower calibrated amount and the upper calibrated amount. The interpolation may be performed based on a rationality check operation performed when the dual-fuel engine system 10 is operated in a single fueling mode using the first fuel. In some embodiments, the rationality check operation may be performed by the control system 11 in a fueling mode of only the first fuel before the dual-fuel engine system 10 enters the dual-fuel mode. For example, the rationality check operation may be performed immediately before entering the dual-fuel mode from the fueling mode of only the first fuel. The control system 11 may be configured to compare the total indicated power amount with the indicated first fuel power during the rationality check operation. For example, the control system 11 may determine the difference between the total indicated power amount and the indicated first fuel power. In some embodiments, when the control system 11 determines that the difference between the total indicated power amount and the indicated first fuel power is greater than a first threshold amount (which is less than the indicated first fuel power), the control system 11 may determine that at least one first fuel injector has drifted downward. In other embodiments, when the control system 11 determines that the difference between the total indicated power amount and the indicated first fuel power is greater than a second threshold amount (which is greater than the indicated first fuel power), the control system 11 can determine that at least one first fuel injector is substantially unused or newly installed in the dual-fuel engine system 10 (i.e., has a minimum age or a minimum number of service hours).

[0098] The control system 11 may be configured to perform one or more increment operations after the rationality check operation. For example, the control system 11 may be configured to increment the injector first fuel power correction amount (determined in operation 1250) toward the upper calibration amount when the difference between the total indicated power amount and the indicated first fuel power exceeds a first threshold. Conversely, the control system 11 may be configured to increment the injector first fuel power correction amount toward the lower calibration amount when the difference between the total indicated power amount and the indicated first fuel power exceeds a second threshold. In some embodiments, the difference between the total indicated power amount and the indicated first fuel power amount exceeding the second threshold may indicate that at least one first fuel injector was recently replaced during service of the dual-fuel engine system 10. In various embodiments, the control system 11 may be configured not to perform an adjustment to the injector first fuel power correction amount. For example, the control system 11 may determine not to increment the injector first fuel power correction amount toward the upper calibration amount or the lower calibration amount.

[0099] In various embodiments, the control system 11 is configured to store the injector first fuel power correction amount ("age factor") in a non-volatile memory so that the injector first fuel power correction amount is saved and can be used to restore and / or reuse across one or more cycles of the internal combustion engine 20. For example, in various embodiments, the injector first fuel power correction amount can be restored by the control system 11 during one or more critical cycles (e.g., power-off cycles) of the internal combustion engine 20. In various embodiments, the injector first fuel power correction amount can be adjusted by the control system 11 based on the service of the dual-fuel engine system 10. For example, in some embodiments, if at least one first fuel injector is replaced, the control system 11 can be configured to reset the injector first fuel power correction amount to zero. In other embodiments, when the dual fuel kit is installed on an engine (e.g., engine 20) having an age exceeding a threshold, the control system 11 can adjust the injector first fuel power correction amount to a higher value. For example, when the engine is a relatively aged engine, the control system 11 can adjust the injector first fuel power correction amount to a higher value. In various embodiments, the upper limit calibration amount is 1 and the lower limit calibration amount is 0.

[0100] In various embodiments, the control system 11 is configured to determine the indicated first fuel power amount from the adjustment determination operation using one or more interpolation functions, such as Fig.14 , which illustrates method 1300. In various embodiments, operations 1305-1365 of method 1300 are similar to or equivalent to corresponding operations 1105-1165 of method 1100. Fig.14 As shown, the adjustment determination operation (i.e., determining the indicated first fuel power) performed by the control system 11 may include executing one or more interpolation functions in operation 1375. In various embodiments, the execution of one or more interpolation functions may be based on the indicated first fuel power amount of the first injector (determined in operation 1365), the indicated first fuel power amount of the second injector (determined in 1345), and an interpolation factor. In various embodiments, the control system 11 may be configured to determine the interpolation factor based on the injector first fuel power correction amount ("age factor") and / or the age fraction parameter determined in operation 1130. In various embodiments, the control system 11 may be configured to determine the interpolation factor by calculating the product of the injector first fuel power correction amount ("age factor") and the age fraction parameter.

[0101] In various embodiments, the control system 11 may be configured to output an indicated first fuel power amount corresponding to the indicated first fuel power amount of the first injector (i.e., such as the indicated first fuel power amount corresponding to the new first fuel injector determined in operation 1365) when the interpolation factor has a first value. For example, the first value of the interpolation factor may be zero. Conversely, the control system 11 may be configured to output an indicated first fuel power amount corresponding to the indicated first fuel power amount of the second injector (i.e., such as the indicated first fuel power amount corresponding to the EOL first fuel injector determined in operation 1345) when the interpolation factor has a second value. For example, the second value of the interpolation factor may be 1. Thus, when executing method 1300, the control system 11 may perform one or more interpolation functions in operation 1375 by interpolating between the first value and the second value to determine the indicated first fuel power amount in operation 1005.

[0102] In other embodiments, Fig.15 As shown, the control system 11 can be configured to perform the method 1400. In various embodiments, the operations 1410-1475 of the method 1400 are similar to or equivalent to the corresponding operations 1310-1375 of the method 1300. Fig.15 As shown, the control system 11 may be configured to determine one or more interpolation factors in operation 1485. For example, Fig.15 As shown, the control system 11 may be configured to determine one or more interpolation factors by executing one or more age factor adaptation algorithms in operation 1480. In various embodiments, the one or more age factor adaptation algorithms in operation 1480 may be similar to or equivalent to the age factor adaptation algorithm executed in operation 1267.

[0103] In various embodiments, the control system 11 may be configured to implement one or more of the methods 900, 1000, 1100, 1200, 1300, or 1400 to compensate for drift within the first fuel control system 14 and / or the second fuel control system 16. For example, in some embodiments, the control system 11 may be configured to perform one or more of the methods 1000, 1100, 1200, 1300, or 1400 before or after performing the method 900. In still other embodiments, the control system 11 may be configured to perform one or more of the methods 1000, 1100, 1200, 1300, or 1400 in parallel or sequentially with the method 900. For example, in some embodiments, determining the amount of the second fuel in operation 950 may include performing any of the methods 1000, 1100, 1200, 1300, and / or 1400, or any one or more operations thereof. In still other embodiments, the control system 11 may be configured to perform one or more of methods 1000 , 1100 , 1200 , 1300 , or 1400 (or one or more operations thereof) when performing operations 930 , 940 , 945 , 950 , and / or 955 .

[0104] Although the above reference Figure 1-Figure 15 Embodiments are described, but various modifications and inclusions of those embodiments are considered to be within the scope of the present disclosure.

[0105] The present technology may also include, but is not limited to, the features and combinations of features described in the following lettered paragraphs, and it should be understood that the following paragraphs should not be interpreted as limiting the scope of the appended claims or requiring that all such features must be included in these claims:

[0106] A. A method of controlling a dual fuel engine configured to receive a first fuel and a second fuel, the method comprising:

[0107] operating the engine using a first fuel;

[0108] The current load of the engine is measured by the controller;

[0109] sending a first signal by the controller to the first fuel system to deliver a quantity of the first fuel to the engine;

[0110] determining, by the controller, at least one first operating parameter associated with the engine;

[0111] determining, by a controller, an engine load estimate based on the first signal and at least one first operating parameter;

[0112] The engine load estimate is compared, by the controller, to the measured current load; and based on the comparison, an adjusted engine load estimate is determined, by the controller, to compensate for drift in the first fuel system.

[0113] B. The method according to paragraph A, further comprising:

[0114] An amount of the second fuel to be delivered to the engine is determined by the controller.

[0115] C. A method as described in paragraph B, wherein determining the amount of the second fuel to deliver to the engine is based on comparing the engine load estimate to a measured current load.

[0116] D. A method according to any one of paragraphs B or C, further comprising:

[0117] operating the engine, by the controller, using the adjusted engine load estimate during one of a predetermined number of cycles or during a predetermined period of time;

[0118] Therein, the amount of the second fuel is determined based on at least one second operating parameter determined during a predetermined number of cycles or a predetermined time period.

[0119] E. A method according to any of the preceding paragraphs, further comprising determining, by the controller, a parasitic load on the engine.

[0120] F. The method of paragraph E, wherein determining the parasitic load on the engine includes determining, by the controller, a load corresponding to at least one cooling fan.

[0121] G. The method of paragraph F, wherein determining the engine load estimate includes determining, by the controller, a net engine load.

[0122] H. The method of paragraph G, wherein determining the net engine load comprises:

[0123] estimating, by the controller, a total engine load; and

[0124] Subtract parasitic loads.

[0125] I. A dual fuel engine system, comprising:

[0126] an engine configured to receive a first fuel and a second fuel;

[0127] a first fuel system for delivering a first fuel to the engine;

[0128] a second fuel system for delivering a second fuel to the engine;

[0129] a controller operably coupled to each of the engine, the first fuel system, and the second fuel system, the controller configured to:

[0130] transmitting a first signal to one of the first fuel system or the second fuel system to cause the first fuel system or the second fuel system to deliver a quantity of the corresponding first fuel or second fuel;

[0131] Measures current engine load;

[0132] determining at least one first operating parameter of the engine;

[0133] determining an engine load estimate based on at least one first operating parameter and an amount of the first fuel or the second fuel;

[0134] comparing the engine load estimate to the current engine load; and

[0135] Based on the comparison, an adjusted engine load estimate is determined to compensate for drift in one of the first fuel or the second fuel.

[0136] J. The dual fuel engine system of paragraph I, wherein the controller is further configured to determine an amount of the other fuel of the first fuel or the second fuel to be delivered to the engine.

[0137] K. The dual fuel engine system of paragraph J, wherein the controller is configured to determine an amount of the other of the first fuel or the second fuel based on at least one second operating parameter.

[0138] L. A dual fuel engine system as described in any of paragraphs I-K, wherein the current engine load is based on at least one of engine torque or engine speed.

[0139] M. The dual fuel engine system of any of paragraphs I to L, further comprising a generator driven by the engine, wherein a current engine load is based on a current and a voltage corresponding to the generator.

[0140] N. A dual fuel engine system according to any one of paragraphs I to M, wherein at least one first operating parameter includes at least one of the following: engine speed, coolant temperature, oil temperature, coolant pressure, oil pressure, intake manifold pressure, intake manifold temperature, exhaust manifold temperature, exhaust manifold pressure, injection timing or injection pressure.

[0141] O. A dual fuel engine system according to any one of paragraphs I to N, wherein the first signal includes at least one of the following: an electrical signal, a hydraulic parameter, or a mechanical adjustment.

[0142] It should be noted that the term "exemplary" and variations thereof as used herein to describe various embodiments are intended to indicate that these embodiments are possible examples, representations, or illustrations of possible embodiments (and these terms are not intended to imply that these embodiments are necessarily the most specific or superlative examples).

[0143] As used herein, the term "coupled" and variations thereof refer to two components being directly or indirectly joined to one another. Such joining may be stationary (e.g., permanent or fixed) or movable (e.g., removable or releasable). Such joining may be achieved using two components that are directly coupled to one another, wherein the two components are coupled to one another using a separate intermediate component and any additional intermediate components that are coupled to one another, or wherein the two components are coupled to one another using an intermediate component that is integrally formed with one of the two components as a single entity. If "coupled" or variations thereof are modified by additional terms (e.g., directly coupled), the general definition of "coupled" provided above is modified by the plain language meaning of the additional terms (e.g., "directly coupled" means the joining of two components without any separate intermediate components), resulting in a narrower definition than the general definition of "coupled" provided above. Such coupling may be mechanical, electrical, or fluidic.

[0144] References to element positions herein (e.g., "top," "bottom," "above," "below") are only used to describe the orientation of various elements in the drawings. It should be noted that according to other exemplary embodiments, the orientation of various elements may be different, and such variations are intended to be included in the present disclosure.

[0145] In some embodiments, hardware and data processing components for implementing various processes, operations, illustrative logic, logic blocks, modules, and circuits described in conjunction with the embodiments disclosed herein, such as hardware and data processing components of a controller (e.g., memory within the controller 18, memory within the OEM system 12, memory within the first fuel control system 14, or memory within the second fuel control system 16), can be implemented or executed using a general purpose single-chip or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some embodiments, specific processes and methods may be performed by circuits specific to a given function. Memory (e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, flash memory, hard disk storage) for storing data and / or computer code to accomplish or facilitate the various processes, layers, and modules described in the present disclosure. Memory may be or may include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. According to an exemplary embodiment, memory (e.g., memory within controller 18, memory within OEM system 12, memory within first fuel control system 14, or memory within second fuel control system 16) is communicatively connected to a processor via processing circuitry and includes computer code for executing (e.g., by processing circuitry or a processor) one or more processes described herein.

[0146] The present disclosure contemplates methods and systems for implementing various operations on any machine-readable medium, such as, for example, operations 305-360 of method 300, operations 405-470 of method 400, operations 505-545 of method 500, operations 605-655 of method 600, operations 705-740 of method 700, operations 805-845 of method 800, operations 905-955 of method 900, operations 1005-1055 of method 1000, operations 1105-1165 of method 1100, operations 1210-1270 of method 1200, operations 1305-1375 of method 1300, and operations 1410-1485 of method 1400. Embodiments of the present disclosure may be implemented using an existing computer processor, or by a dedicated computer processor of an appropriate system introduced for this purpose or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products, which include machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available medium, which can be accessed by a general-purpose or special-purpose computer or other machine with a processor. For example, such machine-readable media may include RAM, ROM, EPROM, EEPROM or other optical disk storage, disk storage or other magnetic storage devices, or any other medium that can be used to carry or store the required program code in the form of machine-executable instructions or data structures and can be accessed by a general-purpose or special-purpose computer or other machine with a processor. The above combination is also included in the scope of machine-readable media. Machine-executable instructions include instructions and data that, for example, enable a general-purpose computer, a special-purpose computer or a special-purpose processing machine to perform a certain function or a group of functions.

[0147] Although the drawings and the specification may show a specific order of method steps, the order of these steps may be different from that depicted and described, unless otherwise specified above. In addition, two or more steps may be performed simultaneously or partially simultaneously, unless otherwise specified above.

[0148] It is important to note that any element disclosed in one embodiment may be combined or used with any other embodiment disclosed herein. Although only one example of an element from one embodiment that may be combined or utilized in another embodiment is described above, it should be understood that other elements of the various embodiments may be combined or used with any other embodiment disclosed herein.

Claims

1. A method of controlling a dual fuel engine configured to receive a first fuel and a second fuel, the method comprising: operating the engine using the first fuel; measuring, by a controller, a current load of the engine; sending a first signal by the controller to a first fuel system to deliver a certain amount of the first fuel to the engine; determining, by the controller, at least one first operating parameter associated with the engine; determining, by the controller, an engine load estimate based on the first signal and the at least one first operating parameter; The controller compares the engine load estimate to a measured current load; and based on the comparison, the controller determines an adjusted engine load estimate to compensate for drift in the first fuel system.

2. The method according to claim 1, further comprising: An amount of the second fuel to be delivered to the engine is determined by the controller.

3. The method according to claim 2, wherein: Determining an amount of the second fuel to deliver to the engine is based on comparing the engine load estimate to the measured current load.

4. The method according to claim 2, further comprising: operating the engine using the adjusted engine load estimate by the controller during one of a predetermined number of cycles or during a predetermined period of time; Wherein the amount of the second fuel is determined based on at least one second operating parameter determined during the predetermined number of cycles or the predetermined time period. 5 . The method of claim 1 , further comprising determining, by the controller, a parasitic load on the engine.

6. The method according to claim 5, wherein: Determining the parasitic load on the engine includes determining, by the controller, a load corresponding to at least one cooling fan.

7. The method according to claim 6, wherein: Determining the engine load estimate includes determining, by the controller, a net engine load.

8. The method according to claim 7, wherein: Determining the net engine load includes: estimating, by the controller, a total engine load; and Subtract the parasitic load.

9. A dual fuel engine system comprising: an engine configured to receive a first fuel and a second fuel; a first fuel system for delivering the first fuel to the engine; a second fuel system for delivering the second fuel to the engine; a controller operably coupled to each of the engine, the first fuel system, and the second fuel system, the controller configured to: transmitting a first signal to one of the first fuel system or the second fuel system to cause the first fuel system or the second fuel system to deliver a quantity of the corresponding first fuel or second fuel; Measures current engine load; determining at least one first operating parameter of the engine; determining an engine load estimate based on the at least one first operating parameter and the amount of the first fuel or the second fuel; comparing the engine load estimate to the current engine load; and Based on the comparison, an adjusted engine load estimate is determined to compensate for drift in one of the first fuel or the second fuel.

10. The dual fuel engine system according to claim 9, wherein: The controller is also configured to determine an amount of the other of the first fuel or the second fuel to be delivered to the engine.

11. The dual fuel engine system according to claim 10, wherein: The controller is configured to determine an amount of the other of the first fuel or the second fuel based on at least one second operating parameter.

12. The dual fuel engine system according to claim 9, wherein: The current engine load is based on at least one of engine torque or engine speed.

13. The dual fuel engine system according to claim 9, further comprising a generator driven by the engine, wherein: The current engine load is based on a current and a voltage corresponding to the generator.

14. The dual fuel engine system according to claim 9, wherein: The at least one first operating parameter includes at least one of: engine speed, coolant temperature, oil temperature, coolant pressure, oil pressure, intake manifold pressure, intake manifold temperature, exhaust manifold temperature, exhaust manifold pressure, injection timing, or injection pressure.

15. The dual fuel engine system according to claim 9, wherein: The first signal includes at least one of: an electrical signal, a hydraulic parameter, or a mechanical adjustment.

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