Fuel quality determination system and its operating method

Abstract

The present invention relates to a system for determining the characteristics of fuel supplied to an internal combustion engine and adjusting the operation of the internal combustion engine based on the determined characteristics. The system includes an airflow throttle configured to control the air supplied to the internal combustion engine, a fuelflow throttle configured to control the fuel supplied to the internal combustion engine, an oxygen sensor for engine exhaust, and a controller configured to receive and control the operation of the throttle. The controller is configured to execute a fuel-air determination program that determines a percentage error air-fuel ratio (AF) by comparing the true air-fuel ratio with an ideal air-fuel ratio. Furthermore, the controller is configured to execute a fuel characteristic determination and adjustment program that adjusts the operation of the internal combustion engine based on fuel characteristic values ​​determined based on the percentage error AF.

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Application No. 63 / 487,638, filed on March 1, 2023, with the United States Patent and Trademark Office, titled "Fuel Quality Determination System and Method of Operating the Same", and the entire disclosure of that application is incorporated herein by reference.

[0002] This disclosure relates primarily to throttles for natural gas engines, particularly applicable to large natural gas engines used in the oil and gas industry. More particularly, it relates to systems and methods for controlling the mass flow rate into the combustion chambers of large gaseous fuel spark ignition internal combustion engines using throttles and engine control systems.

Background Art

[0003] In natural gas engines in the oil and gas industry, throttle valves have been used for many years. Since natural gas fuel is usually obtained directly or indirectly from the wellhead, its quality is often difficult to predict. Natural gas fuel from the wellhead may be supplied directly through pipes or may be supplied after passing through filters and dryers, but natural gas fuel used in the field of this disclosure is usually unrefined.

[0004] Despite fluctuations in fuel quality, accurate flow control is necessary for natural gas engines to burn with optimal efficiency based on the requirements of the engine control module (ECM). Particularly in non-choked flow, it is difficult to achieve precisely controlled mass flow rates. In large engines, electronic throttles are commonly used to control the mass flow rates of fuel and air. Advancements in ECMs have significantly improved the ability to optimize efficiency and performance and minimize emissions-related problems in spark ignition internal combustion engines. The ECM continuously monitors numerous sensors and inputs and can determine the optimal supply flow rate required for the engine at any given moment by balancing current operator commands and performance conditions.

[0005] Achieving such optimal control becomes even more difficult when the fuel is unrefined natural gas. In natural gas engines in other fields, the characteristics of the fuel supply are often known, and in such cases, precise adjustments can be made to meet emission regulations and other performance requirements while obtaining maximum output. However, when the quality and composition of the fuel are unknown or fluctuate over time, the engine adjustment process becomes difficult, and manual measurement is often required to ultimately supply the precise fuel mass flow rate required by the engine. In such circumstances, the system and method of this disclosure can greatly improve automatic adjustment to the engine by accurately determining the air mass flow rate and fuel mass flow rate at any point during engine operation.

[0006] Therefore, there has long been a need for an engine control system that can not only accurately and stably supply the mass flow rate required by the ECM at the site, but also provide users with information on the quality of the natural gas used as fuel, and furthermore, control non-choke flow. Non-choke flow is common in low-pressure supply flow, but also occurs in many high-pressure scenarios. For background information on a comparison with mass flow control based on choke flow, please refer to Patent Document 1 (U.S. Patent No. 9,957,920). The full text of said patent is incorporated herein by reference. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent No. 9,957,920 [Overview of the project] [Problems that the invention aims to solve]

[0008] Those skilled in the art will see that by appropriately utilizing the embodiments described herein, not only the problems mentioned above but also many other unresolved difficulties, problems, obstacles, limitations, and challenges can be solved. This is particularly evident when the descriptions detailed below are considered in the context of a comprehensive understanding of the prior art. [Means for solving the problem]

[0009] This disclosure enables real-time determination of natural gas fuel quality in a large spark-ignition internal combustion engine by combining mass flow data and combustion data using a high-speed, high-precision gas supply throttle. This is particularly beneficial for engines that use unrefined natural gas as a fuel source. Preferred embodiments often target non-choke flow in low-pressure applications, yet still achieve extremely high-precision mass flow control. Furthermore, an objective of this disclosure is to perform flow control in response to instantaneous request signals from the engine ECM and to consistently maintain extremely high accuracy over a large dynamic power range, even in the presence of upstream, downstream, and intermediate pressure fluctuations.

[0010] The disclosed embodiments include a system and method for using a combination of a mass flow air (MFA) throttle and a mass flow gas (MFG) throttle, further combined with an oxygen sensor. This determines the mass flow rates of air and gas. Furthermore, based on the configuration of the throttle and other components of the system, fuel characteristics, such as the British calorific value (BTU) content of the fuel, can be accurately estimated, thereby enabling automatic engine calibration and other adjustments. This is particularly useful when the fuel quality is unknown or fluctuates over time.

[0011] Possible embodiments can be realized in various different combinations in the form of improved machines, internal combustion engines, gas supply control systems, etc. Other embodiments can be realized in the form of methods for operating and optimizing these machines, engines, systems, etc., or other types of methods. All of the multifaceted elements of this disclosure and their combinations, substitutions, and modifications can be considered as independent disclosures.

[0012] The combinations described herein offer not only greater versatility and reliability, but also achieve higher accuracy under rapidly changing conditions and over a wide dynamic output range that was not achievable with conventional, simpler systems. Various embodiments improve upon the related technologies in terms of reliability, manufacturability, cost, efficiency, ease of use, ease of repair, and ease of adaptability. The embodiments referenced below are far from an exhaustive list, but describe selected examples that are considered to realize many of the fundamental elements. [Effects of the Invention]

[0013] In accordance with many of the teachings of this disclosure, a throttle is provided that can be easily adapted to the power requirements of various applications and that can control the gas supply flow rate with high setpoint accuracy over a very wide dynamic power range in an internal combustion engine. Such a flow-controlled throttle and associated fuel system deviates significantly from the concepts and designs of the prior art and thereby provides numerous advantages and novel features that are not anticipated, easily conceived, or suggested by any single or obvious combination of the prior art.

[0014] The throttles taught in this disclosure, through their innovative combination of features and elements, can consistently achieve highly reliable and extremely precise mass flow control for a variety of large engine applications, even in non-choke flows. Features and elements that enable this result include the use of a one-piece block assembly for the throttle, a high-speed actuator, a single, rigid, one-piece rotating shaft for driving the throttle blades (supported by three different bearing assemblies along its length), and an assembly that integrally houses the control circuit with the rotating actuator and the throttle itself, all of which help minimize play in the control. Furthermore, the disclosure preferably includes at least partially redundant pressure sensors, which allow the controller to self-monitor the various sensors in real time.

[0015] A particularly advantageous aspect achieved by applying this disclosure is a throttle system comprising a controller adapted to estimate fuel quality characteristics in accordance with the teachings of the disclosed embodiments, and a method for controlling such a system. Such a system and method preferably use in combination an MFG throttle for controlling the mass flow rate of fuel and an MFA throttle configured to control the mass flow rate of air or the mass flow rate of an air-fuel mixture. Such a combination allows the controller to control the operation of the throttle and estimate the characteristics of the fuel flow controlled by the MFG throttle by interpolating in reverse, thereby enabling further fine-tuning of the throttle and other interventions.

[0016] To gain further insight into such determination, preferred embodiments deploy a throttle with high-speed and precise control, thereby achieving a precisely controllable mass flow rate even with relatively low-pressure fuel supply and subsonic, non-choke throttle flow rates. The required precision is achieved, in part, by embodiments using high-speed response transducers integrally mounted on the throttle position control board, thereby monitoring the position of the throttle shaft quickly and accurately at almost the same speed as its control. Furthermore, preferred embodiments also ensure high-speed and precise control, in part, by precisely measuring fluid pressure sampled from both upstream and downstream of the throttle, preferably via pressure ports positioned upstream and downstream of the central axis of the throttle blade at intervals of less than half the throttle diameter, respectively. The upstream and downstream pressure measurements are preferably reinforced by a third pressure sensor, i.e., a ΔP sensor. The upstream and downstream pressure sensors themselves, as well as all three pressure sensors, are preferably mounted on the same throttle position control board.

[0017] In systems where engine output horsepower consumption is monitored (compressor bhp / generator kW), the change in fuel characteristics (BTU / kW) can be estimated by using the MFG alone. Furthermore, software adaptation is preferably included to automatically adjust the engine based on the change in BTU. Based on the BTU input, the target φ value (pre-catalytic and / or post-catalytic), ignition timing, and / or maximum allowable load can be changed. The φ value is the ratio of the stoichiometric air-fuel ratio to the actual air-fuel ratio in an internal combustion engine. As a second verification, the ignition timing can be adjusted and the knock level can be measured. This helps correlate the expected relationship between BTU content and methane number. The engine ECM, or the air and fuel valve controllers described later, can output fuel characteristic information to the gas compressor, allowing for more accurate prediction of compressor output and compressor (and internal stage) information. The engine ECM or air and fuel valve controllers can also output fuel characteristic information to assist in the monetization and metering of fuel supplied through the pipeline.

[0018] Another important and advantageous aspect of the disclosed embodiment is the development of an approach to minimize damage from backfire events in an engine using the throttle as taught in the appended disclosure. Specifically, if a backfire event is detected by a pressure surge in the downstream pressure port—and the pressure surge significantly exceeds the level of pressure fluctuations under normal operation (e.g., more than 50%)—the microcontroller is programmed to instantaneously open the throttle blades for at least 150 milliseconds. After that period, the microcontroller returns the throttle to normal operation. Due to the high-speed operating characteristics of the disclosed throttle embodiment, this method has been found to minimize damage such as bending of the throttle blades and / or throttle shaft.

[0019] Another aspect of the disclosed embodiment is the use of a combination of MFA throttle and MFG throttle, which can significantly shorten the development cycle of engines using such throttles.

[0020] For the sake of comprehensiveness, many other aspects, purposes, features, and advantages of this disclosure will become apparent to those skilled in the art by a careful and comprehensive examination of the following description and accompanying drawings from the perspective of the prior art. These aspects, purposes, features, and advantages are also intended to be included within the scope and spirit of this disclosure. However, the detailed description and specific examples, while illustrating preferred embodiments of this disclosure, are provided only as illustrations, for various extensions, changes, and modifications within the spirit and scope of this disclosure will become apparent to those skilled in the art from this detailed description.

[0021] In fact, this disclosure will ultimately be defined in relation to one or more patent claims or groups of claims that are added to this specification or that claim priority to this specification. These claims may be modified, divided, refined, revised, replaced, supplemented, or otherwise modified over time. The scope of the corresponding disclosure will depend on these claims, but for convenience, this description may refer to the “disclosure” or “this disclosure” as if its particular scope were already fully understood at the time of this description. In fact, since multiple independent and distinct disclosures may be appropriately requested under this specification, references to the “disclosure” are variable references that refer to what is defined by the final form of the corresponding patent claims. Accordingly, where this description refers to a form of the disclosure that is not individually requested in the final patent claims, such references should not be constrained, nor should they be interpreted as describing a variation of the disclosure.

[0022] Therefore, this disclosure is not limited to the structural details, component arrangements, or drawings described in the following description. Rather, the drawings are merely illustrative, and any specific details shown or described, including those referred to as "preferred," may be modified, and such modifications will still be within the spirit of this disclosure. Furthermore, the expressions and terminology used herein are for illustrative purposes only and should not be constrained. In addition, other terms and language used to describe this disclosure and its embodiments and their functions are also considered to be within the spirit of this disclosure.

[0023] This disclosure is capable of many other embodiments and can be implemented and performed in a variety of other ways. It should also be understood that there are many other alternative embodiments that are not illustrated or mentioned, although they remain within the scope of the spirit of this disclosure. This disclosure will ultimately be limited only by the scope of the original, additional, or modified claims in this application or any other patent application claiming priority to this application in the future.

Brief Description of the Drawings

[0024] The various features and advantages of the present disclosure are described with reference to the drawings of preferred and alternative embodiments. These drawings illustrate but do not limit the present disclosure, and the reference numerals may indicate similar elements in some cases. [Figure 1] A diagram showing a fuel quality determination and engine control system according to an embodiment of the present disclosure. [Figure 2A] A perspective view of a suitable mass flow throttle. [Figure 2B] A perspective view of a suitable mass flow throttle. [Figure 2C] A front view of a suitable mass flow throttle. [Figure 2D] A notch view of the suitable mass flow throttle shown in FIG. 2C, showing a cross-section along the cross-sectional plane B - B. [Figure 3A] An exploded perspective view of a suitable mass flow throttle. [Figure 3B] An exploded perspective view of a mass flow throttle according to another embodiment of the present disclosure. [Figure 4] A perspective view of a throttle body assembly according to an embodiment of the present disclosure. [Figure 5A] An exploded perspective view of a spring assembly according to an embodiment of the present disclosure. [Figure 5B] An exploded perspective view of the spring assembly of the mass flow throttle shown in FIG. 3B. [Figure 6] An exploded perspective view of a thermistor assembly according to an embodiment of the present disclosure. [Figure 7] An exploded perspective view of a motor and throttle shaft assembly according to an embodiment of the present disclosure. [Figure 8] An exploded perspective view of an intermediate housing assembly according to an embodiment of the present disclosure. [Figure 9] An exploded perspective view of a PCB assembly according to an embodiment of the present disclosure. [Figure 10]This is a block diagram of a gaseous fuel supply system with a large engine MFG throttle according to one embodiment of the present disclosure, which is operationally integrated with an internal combustion engine and controls the gaseous fuel supply with high precision. [Figure 11A] This flowchart shows a method for determining the quality of fuel to be burned, using fuel-air mass flow characteristics that can be achieved by a system including a fuel throttle and a fuel-air throttle, and information from an exhaust gas oxygen sensor, in accordance with the teachings of this disclosure. [Figure 11B] This flowchart illustrates a method using air-fuel ratio characteristics that can be achieved by a system using two throttles, in accordance with the teachings of this disclosure, and is a diagram for further understanding the method described in Figure 11A. [Figure 11C] Figures 11A and 11B are block diagrams that further illustrate the methods used, showing methods for determining specific fuel characteristics and control strategies for adjusting those fuel characteristics. [Figure 12] This figure shows a typical fuel table used to estimate specific fuel characteristics. [Figure 13] This figure shows representative response curves that serve as supplementary data for estimating specific fuel characteristics. [Figure 14] This figure shows a fuel recovery system incorporating the power system of this disclosure. [Figure 15A] This is a downstream perspective view of a throttle valve assembly including a perforated annular detection ring according to one embodiment of the present disclosure. [Figure 15B] This is an upstream perspective view of a throttle valve assembly including a perforated annular detection ring according to one embodiment of the present disclosure. [Figure 16A] This figure shows the upstream detection ring of the throttle valve assembly shown in Figure 15A. [Figure 16B] This figure shows the downstream detection ring of the throttle valve assembly shown in Figure 15B. [Figure 17] Figures 15A and 15B show cross-sectional views of the throttle valve assembly. Detailed description of the invention

[0025] The following examples are provided to illustrate preferred embodiments for actually implementing the Disclosure, as well as certain preferred alternative embodiments that may be particularly useful at the time of writing. In the process of understanding these preferred and alternative embodiments, those skilled in the art will gain a deeper understanding not only of the Disclosure but also of the various methods for creating and using the Disclosure and its embodiments. [Interpretation of Terms]

[0026] For the purpose of understanding this statement, certain abbreviations of certain terms should be understood universally, unless otherwise explicitly stated in the specification or claims to differ in a particular context. For the purpose of understanding statements fundamental to this disclosure, the term “or” should be presumed to mean “and / or” unless it is specifically stated to refer only to alternatives or the choices are inherently mutually exclusive. When referring to values, the term “about” may be used to indicate an approximation and generally means a value for a particular embodiment disclosed, or a value including an error of the standard deviation commonly used to determine or achieve such a value. A reference to one element (often introduced with an article such as “a” or “an”) may mean one or more unless explicitly stated otherwise. Such “one or more” meanings are particularly intended when referred to in conjunction with open words such as “having,” “comprising,” or “including.” Similarly, “another” may mean at least a second or more. Other words or phrases have meanings defined herein or in the accompanying background or summary statements, and those defined meanings should be presumed to apply unless the context suggests otherwise.

[0027] This description may point out and offer perspectives on various possible alternatives to reinforce that the disclosure is not limited to any particular embodiment. However, the alternatives described are still merely examples and do not exhaustively identify all alternatives that may be known at the time of this description. The description may sometimes rank certain alternatives as “most preferred” or “more preferred,” but such ranking perspectives should be of little importance unless they are irrevocably required when the disclosure is finally claimed. In fact, in the overall context of this disclosure, neither preferred embodiments nor referenced alternatives should be interpreted restrictively unless the final patent claim requires a corresponding limitation that is irrevocably required. This is because we recognize that many specific elements of the final patent claim are not necessarily required for infringement under the doctrine of equivalents or other similar legal principles in the United States. Having said that, this disclosure should be presumed to encompass all possible equivalents of the claimed invention, but it should nevertheless be recognized that one or more specific claims may not encompass all alternatives described herein. Such cases would be indicated by an explicit waiver of rights during the examination process, or by limitations required to maintain the validity of a particular claim in light of the prior art.

[0028] At the time of this description, the structural and functional combinations characterized by these examples are considered to represent effective preferred embodiments for implementing this disclosure. However, in light of this disclosure, a person skilled in the art will be able to supplement, correct, or understand any omissions, errors, or simplifications in these descriptions.

[0029] For reference purposes, we classify supply flow rate setting accuracy as follows: We classify a setting accuracy as "approximately accurate" if it is consistently maintained within plus or minus 5% of the requested flow rate across the entire operating range. If it is consistently maintained within plus or minus 3% of the requested flow rate across the entire range, the setting accuracy can be classified as "highly accurate." In more extreme cases, if it is consistently maintained within "approximately" plus or minus 1% of the requested flow rate across the entire operating range, the setting accuracy can be classified as "very accurate."

[0030] Furthermore, while many embodiments may be used to control the mass flow rate of either air or fuel, or a combination of air and fuel, this description generally refers to the control of the “supply flow rate,” which should be understood to mean the control of the supply flow rate of either air, fuel, or a combination thereof. Nevertheless, throttles described herein intended solely to control the fuel supply flow rate will be piped in a different location than throttles for controlling air only. Similarly, throttles positioned to control the mass flow rate of air without fuel will be located in a different location than throttles piped for controlling the fuel-air mixture. We now prefer to combine one throttle that controls only the gaseous fuel supply flow rate (sometimes called a mass flow gas, or “MFG”) with another throttle that controls the supply flow rate after the fuel supply flow rate and air have been mixed further downstream (sometimes called an “MFA,” or mass flow air, even if it includes fuel). Nevertheless, complete and highly accurate mass flow control can also be achieved by combining MFA throttles and MFG throttles of the air supply piped upstream of the fuel-air mixer. Furthermore, when calculating the air mass flow rate using other reliable data, for example, by using an oxygen sensor in combination with pressure, temperature, etc., it is possible to achieve generally accurate overall control by controlling only the fuel mass flow rate without actively controlling the air mass flow rate.

[0031] With respect to any valve, throttle, or actuator, the term “fast-acting” is generally understood by those skilled in the art and should be presumed to mean that, by design, it acts or responds significantly faster or more quickly than most throttles, valves, or actuators. A more restrictive definition may be applied to the extent necessary to maintain the validity of a particular claim in light of the prior art, or if explicitly relinquished during the examination process. Despite the presumed broad meaning, fast-acting actuators as referred to herein are preferably capable of moving the actuated throttle element over a large portion of its operating range, if not its entire range (preferably 20% to 80% of its operating range), in 50 milliseconds or less. However, many other types of actuators are still likely to be suitable alternatives, and are applicable in particular unless a particular claim element explicitly relinquishes requiring a specific fast-acting characteristic.

[0032] In this specification, the term “large engine throttle” (10) is used to describe mass flow throttles of numerous preferred embodiments and refers to the throttle and throttle control system, and not merely to the throttle body assembly (20) or the butterfly valve (or throttle blade) (210) therein. Despite the “large engine” designation attached to the throttle (10), readers should understand that various aspects of such large engine throttles may also be useful for small engines. Therefore, references to “large engine” should not be interpreted restrictively unless estoppel, validity in the prior art, or other legal principles explicitly require an interpretation limited to large engines. The simpler term “throttle” (20) is used synonymously with “throttle body assembly” (20) in this specification. With respect to fuel, the term “fluid” means either liquid or gas, but embodiments of liquid fuel are preferably adapted to vaporize the liquid phase of the fuel before the flow reaches the large engine throttle (10). In the context of supply flow control, a “continuous fluid passage” refers to any type of fluid passage defined through a tube, channel, chamber, baffle, manifold, or other fluid passage that is not interrupted by a fully closed valve, piston, positive displacement pump, or other in the normal operating mode of controlling fuel flow. Therefore, it should be generally understood that a gaseous fluid can always flow continuously through a continuous fluid passage as long as a pressure gradient exists that produces such flow. However, a continuous fluid passage in this context may be adjusted to zero flow rate by reducing the effective area of ​​the opening to zero, but such passage is still considered a continuous fluid passage in this context. Also, unless explicitly denied, an equivalent structure may be fully closed when not operating to control flow, and an equivalent structure may have parallel or alternative passages so that the overall flow is not interrupted even if one or more passages are interrupted. [System Configuration]

[0033] Figure 1 shows a system (1) for determining fuel quality and controlling the mass flow rate of fuel and air supplied to an internal combustion engine (102). Furthermore, system (1) is configured to command the operation of the engine (102) based on the fuel quality determination made to improve the operation of the engine (102) and / or exhaust emissions. System (1) includes an MFG throttle (10) configured to control the mass flow rate of the fuel supply (350), an MFA throttle (140) configured to control the mass flow rate of the fuel-air mixture (150) supplied to the engine (102), and an oxygen sensor (190) configured to measure the oxygen level of the exhaust resulting from the combustion of the fuel-air mixture in the engine (102). As will be described in more detail below, each throttle (10, 140) includes a microcontroller (930) for controlling the operation of the throttle (10, 140). The controller (930) and oxygen sensor (190) of each throttle (10, 140) are interconnected by a controller area network (CAN) (195). In one embodiment, each microcontroller (930) and oxygen sensor (190) are interconnected within the CAN (195) by a CAN hub to which each throttle (10, 140) controller (930) and oxygen sensor (190) is connected. However, as shown in Figure 1, in another embodiment, the CAN (195) does not include a hub, and each controller (930) and oxygen sensor (190) are directly connected to each other through the CAN (195).

[0034] Furthermore, the engine control module (ECM) (100) of the engine (102) (described in more detail later) is communicated with the controller (930) of each throttle (10,140) as indicated by lines (196,197), enabling communication between the ECM (100) and the controller (930). In some embodiments, the connection (196,197) is a wired connection (e.g., RS485 or RS232 connection), and in some embodiments, the connection (196,197) is a wireless connection. In some embodiments, the connection (196,197) may be defined by the Ethernet protocol. In some embodiments, the connection (196,197) is included as part of CAN (195). That is, in some embodiments, the controller (930), ECM (100), and oxygen sensor (190) of each throttle (10,140) are all connected to each other via CAN (195). In another embodiment, the oxygen sensor (190) is not connected to the throttles (10,140) via CAN (195), and the oxygen sensor (190) transmits a measurement value to the ECM (100), which is then configured to relay the measurement value from the oxygen sensor (190) to the controller of the throttles (10,140) via connections (196,197).

[0035] As will be described in more detail below, the connections (196,197) enable the controller (930) to determine fuel characteristic information and transmit it to the ECM (100) so that the ECM (100) can use it when operating the engine. Furthermore, in one embodiment, the controller (930) commands a specific operation of the engine (102) based on calculations and decisions made by the controller (930). Furthermore, according to one embodiment of the present disclosure, the connections (196,197) are used for communication of engine-specific data from the ECM (100) to the controller (930). Such engine-specific data may be used by the controller (930) for, for example, to determine fuel characteristics or to precisely control mass flow. In one embodiment, the ECM (100) transmits engine (102) operating data (e.g., engine load and engine speed) to the controller (930) via connections (196, 197), which the controller (930) can use to determine whether the engine (102) operating conditions are sufficient and appropriate for determining fuel characteristics (this will be discussed later). Furthermore, in one embodiment, the connections (196, 197) are used to communicate throttle (10, 140) operation commands from the ECM (100) to the controller (930).

[0036] The system (1) first operates by controlling the fuel supply (350) from the fuel source (360). Using the MFG (10), the fuel supply (350) discharged by the MFG (10) is supplied to the fuel-air mixer (161), where it is mixed with the air supply (160) to produce a fuel-air mixture (150), which is used to drive the engine (102). The fuel-air mixture (150) supplied to the engine (102) is controlled by the MFA (140). In addition to the illustrated configuration in which the MFA (140) is positioned downstream of the fuel-air mixer (161) so that the fuel-air mixture (150) passes through the MFA (140), there is also an embodiment in which the MFA (140) is positioned upstream of the fuel-air mixer (161) so that the air supply (160) passes through the MFA (140) and is controlled by the MFA (140).

[0037] As will be explained in more detail below, each throttle (10, 140) includes multiple different sensors (pressure sensors (950-952), thermistor (600), throttle blade position sensor (940)) whose sensor measurements are acquired and stored by the controller (930). Each controller (930) and oxygen sensor (190) are configured to send and receive various information to and from each other, such as sensor measurements and commands, and this information is exchanged between the controller (930) and oxygen sensor (190) via CAN (195). Thus, the controller (930) of MFG (10) can perform calculations to control MFG (10) and MFA (140) based on measurements from MFG (10), MFA (140), and oxygen sensor (190). Similarly, the controller (930) of the MFA(140) can perform calculations to control the MFG(10) and MFA(140) based on measurements from the MFG(10), MFA(140), and oxygen sensor (190). Furthermore, the controller (930) of either throttle (10, 140) can also perform calculations to control the specific operation of the engine (102).

[0038] As previously stated, the inventive aspect of this disclosure lies in the fact that the MFG(10) and MFA(140) provide mass flow control of the supply flow (350,150), determine the fuel characteristics of the fuel supply using measurements from the MFG(10), MFA(140) and oxygen sensor(190), and control the operation of the engine(102) based on that fuel quality determination. Although not described in relation to Figure 1, the specific measurements, operations, and calculations performed by the controller(930) when operating the valves(10,140) and the engine(102) to provide mass flow control will be described in more detail below.

[0039] As described above, the operation of the MFA(140) and MFG(10) is fully performed by either controller(930). Therefore, system(1) can operate without control by a master controller such as an ECM. This makes it possible to easily retrofit or "plug-and-play" system(1) into conventional or existing engine systems. Thus, the inventive aspect of this disclosure is that an engine(102) can be retrofitted with system(1) and provide fuel supply(350) and mass flow control of the fuel-air mixture(150) without requiring access to or control of the ECM(100). System(1) has been described as including MFG(10), MFA(140), and oxygen sensor(190), but those skilled in the art will understand that according to other embodiments of this disclosure, system(1) includes other components shown in Figures 1 and 10 (details below).

[0040] As will be described in more detail below, in addition to providing mass flow control for supplying fuel and air to the engine (102), another inventive aspect of system (1) is its ability to determine the fuel characteristics of the fuel supply. Often, the fuel supply comes from a source whose specific characteristics are unknown. System (1) is configured to determine fuel characteristics useful to the operator. In one embodiment, system (1) is configured to determine various fuel characteristics such as BTU value, methane number, and φ value. According to one embodiment, based on the fuel characteristic determination, system (1) is further configured to adjust the operation of the engine (102) to optimize the performance and efficiency of the engine (102) based on the characteristics of the supplied fuel. Furthermore, as will be described below, according to an embodiment in which the fuel supply (350) is a mixture of different fuels, system (1) is configured to determine the proportion of each different fuel in the fuel supply (350). These calculations can be performed by either or both controllers (930). The controller (930) for each valve (10,140) can be called a "calculating controller." That is, one or both of the controllers (930) are configured to perform calculations to control the fuel and air supply to the engine (102), and are also configured to calculate fuel characteristic values ​​that the ECM (100) uses to optimize the performance and operation of the engine (100). [Exploded and non-exploded views of the large engine throttle (10)]

[0041] Referring to Figures 2A and 2B, a perspective view of a preferred large engine throttle (10) is shown. The throttle (140), described herein as MFA, is identical to the throttle (10), described herein as MFG, and those skilled in the art will understand that the description and components of the throttle (10) are identical to those of the throttle (140). For the sake of reducing redundancy, the throttle (10) will be described, but those skilled in the art will understand that the throttle (140) is identical to the throttle (10). As shown, the large engine throttle (10) includes an inlet adapter (30) and an outlet adapter (40). The inlet adapter (30) defines a supply inlet (390) as part of the configuration that introduces the supply flow into the large engine throttle (10). The outlet adapter (40) defines a supply outlet (170) (shown in Figures 2D and 10) as part of the configuration that discharges the supply flow out of the large engine throttle (10). The machine screws (31-34) are combined with machine nuts (31a-34a) to secure the inlet adapter (30) to the housing assembly (20) (shown in more detail in Figures 2C-4). Similarly, the machine screws (41-44) are combined with machine nuts (41a-44a) to secure the outlet adapter (40) to the housing assembly (20). A detailed description of the assemblies and components of preferred embodiments is provided in the following paragraphs.

[0042] Referring to Figure 2C, a two-dimensional view of a large engine throttle (10) is shown. A cooling port (220) (indicated by a dotted frame) is visible on the front of the housing assembly (20), and another cooling port (221) (not shown) is located on the opposite side. In particular, when the throttle (10) is used as a fuel-air (MFA) throttle, hot gases may pass through the throttle (10). To cope with the temperature of such hot gases and to prevent thermal damage to the control circuits and motor (700) associated with the PCB (900), a heat sink (unindicated) is located inside a single block assembly (99) between the main throttle body assembly (20) and the motor (700) and PCB (900). This heat sink preferably takes the form of an aluminum component and encloses one or more passages with a relatively large surface area, allowing the aluminum component to be cooled by a liquid coolant circulating inside it. As those skilled in the art will understand, heat sinks are commonly used in turbocharged applications such as large engine throttles (10). The cooling ports (220, 221) allow coolant to flow into the large engine throttle (10) and circulate around it, preventing the brushless motor (700) (shown in Figure 7) and the main PCB (900) (shown in Figure 9) from overheating.

[0043] Referring to Figure 2D, a cross-sectional view of the embodiment shown in Figure 2C is shown by line B-B, rotated 90 degrees clockwise. The throttle shaft (710) (sometimes called the actuator "drive shaft") controls the movement of the throttle blade (210) and minimizes the room for play and other errors. The upstream pressure P1 (upstream of the throttle blade (210)) is measured by a pressure sensor (951) on the PCB (900) at port (230). The stovepipe of the sensor (951) is connected to port (230) in open fluid communication via an open channel (not shown) running through a single block assembly and a tube between port (230) and the stovepipe of the sensor (951). Similarly, the downstream pressure P2 (downstream of the throttle blade (210)) is measured by a pressure sensor (952) on the PCB (900) at port (240). The stovepipe of the sensor (952) is connected to the port (240) in open fluid communication with the port (240) via an open channel (not shown) running through a single block assembly and a tube between the port (240) and the stovepipe of the sensor (952).

[0044] Each port (230) and (240) has a fluid passage section oriented perpendicular to the flow line of the throttle fluid passage of the throttle (10) in the vicinity of the port, to minimize stagnation or suction pressure caused by this orientation. However, the next adjacent section of each port is oriented to be slightly tilted upward with respect to gravity to minimize the risk of blockage. The fluid temperature is measured at port (250) using a thermistor (600) (shown in Figure 6). Mechanical screws (201-204) integrate the throttle body assembly (20) with the intermediate housing assembly (80).

[0045] Referring to Figure 3A, several of the various assemblies of the embodiment of the single-block assembly (99) of the throttle (10) are shown by dotted lines. Some (but not all) of the embodiments of the throttle (10) employ a single block for each throttle (10), but the assemblies that are tightly integrated to form the single-block assembly (99) include the throttle body (22) of the central throttle body assembly (20), the spring return cover (550) of the spring return assembly (50) located at the right end of Figure 3A, the control circuit cover (901) located at the left end of Figure 3A, and the intermediate housing (800) of the motor housing (80) which is located between the throttle body assembly (20) and the PCB space. To be further understood, numerous screws are used, and embedded seals are used to tightly integrate the subblocks of the embodiment in Figure 3A and preferably to ensure a sealed connection between the various subblocks. Furthermore, two additional subblocks, the inlet extension and the outlet extension, are also integrated into the single-block assembly (99) of Figure 3A. Similarly, the single block assembly (99') of the embodiment shown in Figure 3A is also very similar to assembly (99) in Figure 3A.

[0046] More specifically, the single-block assembly, in a preferred embodiment, consists of various subblocks and covers, primarily made of aluminum. The single-block assembly of the throttle (10) defines the inner and outer surfaces of the throttle (10). The single-block assembly is exemplified as a billet-type assembly of aluminum members shown in various figures 1 to 4, but in a preferred embodiment, for cost reduction in mass production, it may be formed from a large casting with fewer subblocks. Such assemblies are shown in detail in subsequent figures. In Figure 3A, an inlet adapter (30) is shown above the throttle body assembly (20) (shown in more detail in Figure 4). Four screws (31-34), along with a circular seal (35), integrate the inlet adapter (30) with the throttle body assembly (20), allowing for the sealed introduction of mass flow into the throttle body assembly (20) from the upstream side. Similarly, the outlet adapter (40) is integrated with the throttle body assembly (20) using threads (41-44) and a circular seal (45), enabling sealed discharge of the mass flow downstream from the throttle body assembly (20). It should be noted, though of secondary importance, that the inlet adapter (30) and outlet adapter (40) are more beneficial when the throttle (10) is used as an MFG throttle than when it is used as an MFA throttle.

[0047] The multiple spaces defined by a single block assembly—namely, the PCB space housing the rotating shaft (710), the motor space of the intermediate housing (800), the throttle body space, and the spring return assembly space of the assembly (50)—are formed by the sealed integration of adjacent subblocks; however, due to imperfections in the seal around the rotating shaft (710), leakage from one space to the next may still occur. Therefore, to protect the control circuit of the PCB (900) from the corrosive effects of the gaseous fuel supply, the electronic components of the PCB (900) are covered with a coating that protects the electronic components from the corrosive properties of the gaseous fuel.

[0048] A spring assembly (50) (shown in detail in Figure 5A) is located to the right of the throttle body assembly (20). The spring assembly (50) acts as a torsion spring that is wound up while the block assembly (10) is powered on. When the power to the block assembly (10) is turned off, the spring assembly (50) is unwound and returns to the closed position, or more preferably substantially closed position. A thermistor assembly (60) (shown in detail in Figure 6) for sensing temperature is located to the left of the throttle body assembly (20). Also located to the left of the throttle body assembly (20) is a motor and throttle shaft assembly (70) (shown in detail in Figure 7) that controls the movement of the throttle. An intermediate housing assembly (80) (shown in detail in Figure 8) integrates the motor and throttle shaft assembly (70) with a printed circuit board (PCB) assembly (90) (shown in detail in Figure 9).

[0049] As alternatives to the embodiments in Figures 3 and 5, Figures 3A and 5A show comparable but alternative embodiments. However, since the throttle (10') is very similar to the throttle (10), the parts in Figures 3A and 5A are numbered in the same way as the corresponding parts in Figures 3 and 5, with the main difference being that the parts in the embodiments of Figures 3A and 5A are denoted with prime symbols (''). Referring in particular to Figure 3B, almost all subassemblies of the throttle (10') are substantially similar to the subassemblies of the throttle (10) in Figure 3A, with the most notable exception being the spring return assembly (50'), which has components similar to, but different from, those of the spring return assembly (50).

[0050] Nevertheless, the details in Figure 5B are sufficiently different from the similar details in Figure 5A that the explanation is useful. In particular, part (510') is a shaft seal. In this embodiment, the seal retainers (511', 512') are integrated as a single part. Part (501') is a bushing separator that supports a spring (500'), and a screw (531') secures the spring assembly (50') to the end of the throttle shaft (710). The D-shaped notch in the screw (531') tends to position the spring assembly in the desired direction on the shaft (710). The bearing assembly (513') is a conventional bearing assembly similar to the bearing assembly (513), and element (520') is the bearing's play spring. Part (530') is a spring return for returning the throttle blade (210) to a position 5 degrees back from the fully closed position. Each end of the spring (500') has a protruding flare that engages with a notch or the like to drive the spring-driven return of the throttle blade (210), operating in a manner common to many spring-driven returns for automotive throttles. [Throttle body assembly (20)]

[0051] Referring to Figure 4, a perspective view of the throttle body assembly (20) (also referred to as the “gas supply throttle”) is shown. As previously stated, the throttle body assembly (20) may be used to control fuel flow rate, air flow rate, or fuel-air mixture flow rate. The cylindrical space from top to bottom of the throttle body assembly (20) is defined herein as the throttle chamber (205). For a fuel throttle, the throttle opening (200) is preferably in the range of 50 to 76 millimeters in diameter. For a fuel-air throttle, the throttle opening (200) is preferably in the range of 60 to 120 millimeters in diameter. In a preferred embodiment, the throttle opening (200) is a circular opening, but in other embodiments, other shapes may be used, such as a rectangular opening. [Spring assembly (50)]

[0052] Referring to Figure 5A, an exploded view of the spring assembly (50) is shown. On the left side of Figure 5A is the throttle shaft seal (510) (with insert) that seals the throttle shaft (710) (shown in Figure 7). A throttle seal spacer (511) separates the throttle shaft seal (510) from the seal retainer washer (512). A roller bearing (513) is positioned between the seal retainer washer (512) and the wave spring (520). A spring guide bearing (501) prevents the torsion spring (500) from contacting or rubbing against the body of the throttle (10). A larger spring guide bearing (502) separates the torsion spring (500) from the spring return flange (530). A threaded vertical pin (531) located in the central flange (530) of the spring assembly (50) transmits the neutral biasing force of the spring (500) to the shaft (710) and further to the throttle blade (210). Screws (551-554) secure the spring return cover (550) to the throttle body assembly (20), and an O-ring (540) seals and integrates the two assemblies. Referring to an alternative embodiment in Figure 5B, another exploded view of the spring assembly (50') is shown, which has a comparable structure to the spring assembly (50) and functions in general terms. [Thermistor Assembly (60)]

[0053] Referring to Figure 6, an exploded view of the thermistor assembly (60) is shown. In one embodiment, the thermistor (600) has a temperature measurement range of -70°C to 205°C. The thermistor assembly (60) has two O-ring gaskets (603, 604) that function as seals. Lead wires (611, 612) are soldered to thermistor PCB (610), extend through an intermediate housing assembly (80) (not shown), and are also soldered to the main PCB (900). An epoxy overmolding (620) is used to protect the thermistor (600) and thermistor PCB (610). A thermistor tube (630) surrounds the epoxy overmolding (620), thermistor (600), and thermistor PCB (610). The thermistor tube (630) is integrated into the throttle body assembly (20) using screws (640). [Motor and throttle shaft assembly (70)]

[0054] Referring to Figure 7, the motor and throttle shaft assembly (70) is shown. The brushless motor (700) controls the movement of the throttle shaft (710). On the right side of Figure 7 is the throttle shaft seal (711) (with insert). A throttle seal spacer (712) separates the throttle shaft seal (711) from the throttle shaft (710). Four screws (701-704) (three of which are shown) integrate the brushless motor (700) and throttle shaft (710) into the throttle body assembly (20). The throttle shaft (710) passes through the brushless motor (700) and connects to the rotor arm (720). Inside the motor (700) are two rotary bearing assemblies (705, 706), and together with bearing assembly (513) (or 513' in the embodiment of Figure 3A), three bearing assemblies support the rotational motion of the shaft (710). A screw (730) integrally secures the rotor arm (720) to the end of the throttle shaft (710), the end of which protrudes into the PCB space from the left side of the brushless motor (700) (viewpoint in Figure 7). A permanent magnet (740) is permanently attached to the radially outer portion of the rotor arm (720), and the arm (720), in combination with the magnet (740), is used to indirectly measure the position of the throttle blade (210) within its rotational range. [Intermediate housing assembly (80)]

[0055] Referring to Figure 8, the intermediate housing assembly (80) is shown. A large open space (810) is used to house the brushless motor (700). A small circular opening (820) in the lower left is used to house the Controller Area Network (CAN) pin connector protruding from the main PCB (900). A small opening (830) at the top of the assembly (80) houses a backflow prevention check valve (840) to protect the sensor from overpressure. Another small opening (850) houses a forward flow check valve (860) to protect the sensor from overpressure. A grooved seal (870) shaped to fit the intermediate housing assembly (80) seals and integrates the intermediate housing assembly (80) with the throttle body assembly (20). [Printed circuit board (PCB) assembly (90)]

[0056] Referring to Figure 9, the PCB assembly (90) is shown, which seals and houses the PCB (900). The PCB (900) is housed in the space defined between the PCB housing cover (901) and the intermediate housing (800) ("PCB space") and is sealed and integrated by screws (915-920). The sealed bond between the cover (901) and the intermediate housing (800) is partially made possible by a grooved elastic seal (902) positioned around the PCB space. Twelve screws (903-914) firmly secure the PCB (900) and pressure sensors (950-952) to the PCB housing (901). Six screws (915-920) (three of which are illustrated) and the PCB housing seal (902) seal and integrate the PCB assembly (90) and the intermediate housing assembly (80) (shown in Figure 8). Such a sealed, integrated design enables optimal control and minimizes unwanted disturbances and other factors that could affect operation.

[0057] The PCB (900) is equipped with a microcontroller (930), which may be a commercially available microcontroller having memory capable of receiving machine-readable code, i.e., software. The microcontroller (930) provides the "brain" of the large engine throttle (10). The microcontroller (930) receives throttle position signals from the Hall effect sensors (941a~e) of the sensor assembly (940), pressure signals from the pressure sensors (950~952), temperature signals from the thermistor (600), and control signals from the ECM (100). The microcontroller (930) uses an algorithm to calculate the throttle position and outputs pulse-width modulated signals and H-bridge signals to the motor (80) to drive the motor (700) and appropriately control the position of the throttle blade (210) in order to achieve the desired instantaneous mass flow rate. At the same time, it outputs measurement data to the ECM.

[0058] PCB(900) comprises five sets of identical Hall effect sensors (941a-e) that form part of a position sensor assembly for indirectly detecting the position of the throttle blade (210). Referring to Figure 10, these sensors are collectively referred to as the "blade position sensors" (940). When the throttle shaft (710) rotates, the rotor arm (720), which is an integral part of the shaft (710), rotates in the PCB space, causing the magnet (740) to move relative to the Hall effect sensors (941a-e), enabling the sensors to detect changes in the magnetic field. These sensors (941a-e) change their output voltage in response to changes in the magnetic field, and these electrical signals are processed by a microcontroller (930). The sensors (941a-e) are used to calibrate the position of the throttle blade (210) with respect to the strength of the magnetic field provided by the magnet (740).

[0059] The Delta P sensor (950) is a double-sided pressure transducer that measures the differential pressure ("Delta P") between the upstream pressure port (230) and the downstream pressure port (240). Two pressure sensor gaskets (955, 956) seal the Delta P sensor (950). The upstream pressure sensor (951) measures the absolute upstream pressure ("P1") and has a pressure sensor gasket (951a). The downstream pressure sensor (952) measures the absolute downstream pressure ("P2") and has a pressure sensor gasket (953). The Delta P sensor (950) is significantly more accurate in differential pressure measurement than methods that determine the differential pressure by numerical calculation of the difference between P1 and P2. However, there may be conditions under which the throttle operates at a pressure outside the measurement range of the Delta P sensor (950). If the delta-P sensor (950) begins to "stick" (i.e., approach its maximum confidence limit), the microcontroller (930) begins calculating the differential pressure using the pressure sensors (951, 952). If the maximum pressure range is exceeded, the microcontroller (930) stops using the delta-P sensor (950) and switches entirely to the pressure sensors (951, 952) only. In addition, the PCB (900) troubleshoots whenever there is an event that P1, P2 and / or delta-P do not meet the rationality check. In such cases, false signals may be sent to the ECM (100) and / or controllers (930a, 930b).

[0060] The pressure sensors (951, 952) are conventional pressure transducers, but non-conventional ones (or sensors that measure fluid conditions other than pressure, etc.) can also be used as alternatives for some similar purposes. The pressure transducers (951, 952) are preferably of a type that can be mounted on a PCB (900), with a rigid tube connector (often called a "stovepipe") extending from the base, allowing the transducer to access the pressure of the pressure-sensitive object.

[0061] To neutralize the effects of pressure fluctuations—particularly downstream pressure fluctuations—the control algorithm of the microcontroller (930) uses time-averaged pressure readings from pressure sensors (950-952), rather than instantaneous pressure readings. More specifically, the microcontroller (930) continuously calculates the stroke cycle time of the engine (102) pistons based on the number of engine cylinders and the current rotational speed (RPM) received from the ECM (100). [Figure 10 - Block Diagram]

[0062] Figure 10 shows a block diagram of a power system (1402) according to one embodiment of the present disclosure, including the system (1) described earlier. In the exemplary block diagram of Figure 10, four main segments of the supply flow are illustrated for a preferred embodiment: (1) an upstream gaseous fuel supply (350), (2) a large engine MFG throttle (10), (3) an MFA throttle (140), and (4) an engine (102). These four segments (350, 10, 140, 102) are operationally connected to provide rotary shaft power for various large engine applications. The fuel supply (350) functions as the basic gaseous fuel supply to the engine (102), and the large engine throttle (10) and MFA (140) play a role in precisely controlling the flow rates of gaseous fuel and air from the fuel supply (350) and air supply (160) to the engine (102), in accordance with the various teachings of the present disclosure.

[0063] As mentioned above, MFA(140) is the same throttle valve as MFG(10), and its components have been described in detail above. For clarity, in reference to Figure 10 and throughout this specification, each part number of MFG(10) will be denoted with the suffix "a", and each part number of MFA(140) will be denoted with the suffix "b".

[0064] Those skilled in the art will understand that the system (1) in Figure 1 is used within a power system (1402). As previously stated, one of the inventive aspects of this disclosure is that system (1) can precisely control the mass flow rates of fuel supply (350) and air supply (160) to an existing engine system. Accordingly, according to each embodiment of this disclosure, many of the illustrated components and numerous related components, such as the engine (102), fuel tank (360), and fuel-air mixer (161), are existing components that are retrofitted by system (1) to precisely control the mass flow rates of fuel and air to the engine (102). [Upstream fuel supply (350)]

[0065] As shown in Figure 10, the fuel supply (350) preferably includes, in addition to a fuel tank (360) that functions as a source of fluid fuel, other conventional components such as a mechanical pressure regulator (370) and a shut-off gate valve (380). The valve (380) is preferably controlled by an ECM (100), but in alternative embodiments, independent control by controllers (930a, 930b) may be used. The gaseous fuel supply (350) is equipped and adapted to supply gaseous fuel to the supply inlet (390) at a desired pressure level.

[0066] More preferably, the gaseous fuel supply (350) is a natural gas or vaporized propane fuel supply that supplies natural gas or vaporized propane stored in the fuel tank (360). Although not shown in Figure 10, the fuel tank (360) may include a vaporization subassembly and control system for managing the vaporization of LNG (liquefied natural gas) or propane and the associated pressure within the fuel tank (360) and associated piping (365, 375, 376). Such a vaporization subassembly and control system for LNG preferably precirculates a portion of the stored LNG through a heat exchange loop, raising the temperature of the precirculated LNG to a point where it partially or completely vaporizes, forming a vapor phase with a sufficient pressure head within the tank (360). The piping (365) may also preferably be provided with a second heat exchanger downstream of the fuel tank (360) to further assist in the complete vaporization of LNG or propane, allowing the gaseous fuel to flow from the fuel supply (350) to the large engine throttle (10).

[0067] Downstream of the heat exchanger in the piping (365), the gaseous fuel passes sequentially through a mechanical pressure regulator (370), a downstream fuel shut-off valve (380), and a line quick-disconnect assembly (not shown) before entering the large engine throttle (10). In this embodiment, the initial fuel pressure is supplied by the fuel tank (360), which is regulated, preferably by the mechanical pressure regulator (370), before reaching the supply inlet (390) of the large engine throttle (10). The mechanical pressure regulator (370) is capable of handling the low pressure from the fuel tank (360) and includes one or more conventional pressure regulators that vary the effective opening size using a pressure-balancing diaphragm, thereby controlling the pressure at the supply inlet (390) within a desired range. The mechanical pressure regulator (370) preferably includes an integrated pressure sensor that provides the ECM (100) with upstream pressure data (i.e., equivalent to the pressure "P1" at the supply inlet (390)). Whether or not the pressure sensor is integrated into the regulator (370), a preferred embodiment includes a pressure transducer (951) that measures the pressure at a port (230) located upstream of the throttle blade (210) and in fluid proximity to the supply inlet (390). This provides a reliable input regarding the actual pressure of the gas supply flowing into the throttle (10).

[0068] Assuming that the piping (365, 375, 376) is operationally sealed and connected to guide the supply flow into it, the supply flow from the fuel supply (350) to the large engine throttle (10) is permitted or prohibited by the ON / OFF operation of the mechanical shut-off valve (380). In some alternative embodiments, a manual valve may be used, but the valve (380) is preferably actuated by a motor or solenoid through supervised control by the ECM (100). When the shut-off valve (380) is open, the gas supply flow is induced by an operational pressure gradient between the fuel tank (360) and the supply inlet (390). Thus, when the valve (380) is open, the fuel first passes through the heat exchanger and mechanical pressure regulator (370) and then through the valve (380) to enter the fuel inlet (390).

[0069] Even with vaporization subassemblies and controls in place, vaporized natural gas or propane fuel containing droplets of the liquid phase of liquefied natural gas (LNG) or propane may flow. This can occur, for example, if ports or conduits of the heat exchange fluid become blocked. If LNG or propane droplets remain in the fuel flow downstream of the mechanical pressure regulator (370), their subsequent vaporization could cause a large pressure spike in the large throttle engine (10), potentially overwhelming it. To compensate for such inflow of LNG or propane droplets, a pressure control loop can be inserted between the mechanical pressure regulator (370) and the supply inlet (390) of the large engine throttle (10), preferably downstream of the heat exchanger and the mechanical pressure regulator (370).

[0070] If droplets of LNG or propane enter the large engine throttle (10), their delayed vaporization is likely to cause a pressure spike at the supply inlet (390) of the large engine throttle (10). If such a pressure spike occurs, the inserted pressure control loop mitigates the spike, preferably by venting it upstream of the mechanical pressure regulator (370). Alternatively, one or more overpressure vents or bypass check valves can be provided in the piping (375) and / or (376) to prevent vaporization spikes from propagating and interfering with the control of the large engine throttle (10). Similarly, pressure spikes caused by fuel vaporization upstream of the mechanical pressure regulator can also be vented to the atmosphere or diverted to other containers further upstream of the fuel supply (350).

[0071] To control such false pressure spikes, a preferred embodiment controls and regulates the pressure introduced into the supply inlet (390) of the large engine throttle (10) by employing a multifaceted strategy, namely the installation of heat exchangers in the piping (365) and including one or more vents, check valves, etc., as described above, thereby reducing or preventing the flow control from being overwhelmed.

[0072] The fuel tank (360) may alternatively be embodied in one of a number of commonly available gaseous fuel sources, such as a fixed gas pipeline, a compressed gas cylinder, or other types of liquefied storage tanks with vaporization control. This may also include conventional pressure regulators, etc. Preferably, many of these alternatives are also configured to supply fuel from the fuel tank (360) to a large engine throttle (10) via a high-pressure mechanical pressure regulator (370) to regulate the pressure to a desired range relative to the supply inlet (390).

[0073] Again, fuel is supplied from the high-pressure mechanical pressure regulator (370) through a fuel pipe or supply line (375), which is preferably equipped with a shut-off gate valve (380) as shown in the figure. Downstream of the shut-off gate valve (380), the fuel supply line (376) is connected to the supply inlet (390) of the large engine throttle (10), and the fuel is introduced into the gas supply throttle (20) of the large engine throttle (10).

[0074] As those skilled in the art will understand, the supply line (375) may include a fuel filter or other conventional systems for monitoring and / or optimizing fuel supply conditions before being introduced to the large engine throttle (10). Such systems may include, for example, fuel quality sensors connected to the ECM (100) and / or the PCB (900) of the large engine throttle (10) to predict operating needs. The fuel supply (350) may include not only a single pressure regulator (370), but a combination of several independent pressure regulators (370), or an additional pressure regulator integrated into the fuel tank (360).

[0075] Referring again to the preferred embodiment (shown in Figure 10), the large engine throttle (10) includes a fuel supply (350). Downstream of the large engine throttle (10), the supplied fuel flow is mixed with air (160) to form a gaseous fuel-air mixture (150) supplied to the internal combustion engine (102). While the configuration in Figure 10 is preferred, in alternative embodiments following the broader teachings of this disclosure, some or all of the required air may also be introduced to the fuel upstream of the large engine throttle (10) (as indicated by the alternative air-air mixture flow arrow (260')). However, in that case, corresponding challenges and compromises may arise, as adjustments may be necessary to account for airflow introduction depending on the introduction location. [Gas supply throttle (20)]

[0076] The gas supply throttle (10) is adapted to rapidly and accurately control the supply flow rate of the actual mass flow rate ("m with a dot above it (hereinafter, m (dot)")) at the outlet (170) of the MFG (10) in response to the m (dot) flow rate signal, thereby controlling and supplying fuel to the fuel-air mixer (161) and further to the engine (102). Essentially, the gas supply throttle (10) is used to control the gas supply flow from the primary fuel supply (350) (left side of Figure 10) to the internal combustion engine (102) (right side of Figure 10). Therefore, the gas supply throttle (20) is operatively positioned downstream of the fuel supply (350) and upstream of the fuel-air mixer (161) and engine (102), and is piped and sealed to become part of a fluidly continuous fuel supply system during engine (102) operation, with the gas supply throttle (20) located between the fuel supply (350) and the engine (102). A detailed description of the large engine throttle (10) will be provided in a subsequent paragraph with additional drawing references.

[0077] In one embodiment, the desired mass flow rate of the fuel supply (350) is calculated by the ECM (100). In these embodiments, a target air-fuel ratio value is stored in the ECM (100), which in some embodiments is determined by adjustments based on a calibration table and other operating conditions. The ECM (100) is configured to determine the desired mass flow rate of the fuel supply (350) by multiplying the mass flow rate of air passing through the MFA (140) (measured in the MFA (140) and transmitted to the ECM (100) via a communication line (197), or commanded by the ECM (100)) by a target air-fuel ratio. In other embodiments, the desired mass flow rate of the fuel supply (350) may be determined by controllers (930a, 930b). In these embodiments, the target air-fuel ratio value is transmitted from the ECM (100) to the controllers (930a, 930b) via communication lines (196, 197), and can be used by the controllers (930a, 930b) when determining the desired mass flow rate. For example, the controllers (930a, 930b) can determine the desired mass flow rate of the fuel supply (350) by multiplying the received target air-fuel ratio by the mass flow rate of air passing through the MFA (140).

[0078] For further optimization, Inbroch's microcontrollers (930a, 930b) and associated control circuits are preferably mounted on a single printed circuit board (900a, 900b) (also shown in Figure 9). Inbroch's microcontrollers (930a, 930b) are connected to receive m (dot) data signals from the ECM (100) via the aforementioned connections (196, 197). Using the received desired mass flow rate value and the reading from the pressure / temperature sensor (121) from the ECM (100), the printed circuit board (900) controls the large engine throttle (10), preferably without requiring external communication other than power and data connections to the engine's ECM (100). Note that "CAN" is strictly an acronym for Controller Area Network, but the expression "CAN" is generally used as a technical term to refer to the CAN network itself or the data received via the CAN network. Here, a CAN network is preferred as the communication link for all commands, variables, and other data that the microcontroller (930a) receives from outside the throttle system (10), but it should be recognized that wireless, analog signals, digital signals, and other means of communication can also be used as alternatives while satisfying many aspects of this disclosure.

[0079] A CAN network connector (960) (shown in Figure 2D) is also located on the PCB (900a, 900b). As is well known to those skilled in the art, the CAN network connector (960) is a 5-pin connector. The five pins consist of a power pin, a ground pin, a CAN positive pin, a CAN negative pin, and a CAN termination pin. As is well known to those skilled in the art, alternative embodiments may employ direct-connection (0-5V or 5-20mA) data connections, or other known alternative data connections suitable for applications such as large engine throttles (10). In alternative embodiments, an 8-pin connector may be provided instead of the 5 pins in the CAN network.

[0080] In a preferred embodiment, optimal fluid state feedback is obtained by bringing the tip of the stovepipe (or alternatively, the tube therefrom) of a double-sided transducer ("Delta P sensor") (950a, 950b) into direct contact with the fluid in the throttle chamber (205) (see Figure 4), while the base of the transducer (950a, 950b) is directly mounted on the PCB (900a, 900b). Referring to Figure 2D, the Delta P sensors (950a, 950b) measure the differential pressure ("Delta P") between the upstream pressure port (230) and the downstream pressure port (240). Pressure sensors (951a, 951b) measure the absolute upstream pressure ("P1") from port (230), and pressure sensors (952a, 952b) measure the absolute downstream pressure ("P2") from port (240). Referring further to Figure 2D, the stovepipe tips of the pressure sensors (951a, 951b) and (952a, 952b) extend from the PCB (900a, 900b) through sensor supports (230, 240) appropriately positioned on the side wall of the throttle chamber (205). To minimize blockage or other contamination of the transducers (950-952), ports (230) and (240) are preferably located in the lateral compartments of the throttle chamber (205) and shielded by known means used to prevent contamination, such as the use of downward-sloping passages.

[0081] Referring to Figure 6, the sensor tip (601) of the thermistor (600) is placed directly inside the throttle chamber (205), while the base (602) of the thermistor (600) is directly soldered to the thermistor PCB (610) to obtain optimal fluid state feedback. The thermistor (600) is a conventional thermistor that detects temperature at its tip (601) and has lead wires leading to the tip (601), but other types of temperature sensors (or sensors that measure fluid states other than temperature, etc.) can also be used as substitutes for some similar purposes.

[0082] Through overall control by Inbroch's microcontroller (930), each embodiment of the present disclosure addresses long-standing unresolved needs in the art through an innovative approach that overcomes many of the limitations and challenges of the prior art. Following many of the teachings of the present disclosure, industry will be able to offer solutions in the form of large engine control systems that can easily adapt to the power demands of a wide range of applications and that can easily control the supply flow with extremely high precision over a wide dynamic power range in internal combustion engines. [Engine (102)]

[0083] Referring again to Figure 10, the engine (102) is a large spark-ignition internal combustion engine of the type that uses a gaseous fuel as its primary energy source, most preferably natural gas (NG) or vaporized propane (LPG) as fuel. In this specification, a large engine means an engine of 30 liters or more. The engine (102) is preferably used in stationary applications such as generator sets on natural gas compression skids (hereinafter referred to as "gene sets"). Alternatively, the engine (102) may be used in large mobile applications such as trains, ships, mining trucks, and other large vehicles. Conventionally, the engine (102) is equipped with an ECM (100) or equivalent to continuously monitor the operating status of the engine (102) and the components of its surrounding systems. Such an engine (102) can be operationally incorporated into any number of power applications in other embodiments as well as in many other applications that are currently or will be driven by spark-ignition gaseous fuel internal combustion engines, as is known to those skilled in the art.

[0084] The engine (102) ECM (100) is connected via data communication lines or other conventional means to monitor pressure, temperature, and operating conditions in or around numerous subsystems of the engine (102), including the fuel-air treatment system (preferably including a turbocharger (172)), fuel-air throttle (140), ignition system, combustion chamber (180), cooling system, hydraulic system, and exhaust system. In alternative embodiments, some or all of the data connections between the ECM (100) and the various subsystems of the engine (102) may be wireless, but in preferred embodiments, the ECM (100) is connected to send and receive analog or digital signals via wire harnesses or other communication lines. The communication lines are preferably embodied in the form of conventional data networks, such as a controller area network.

[0085] As those skilled in the art will understand, the ECM (100) is partially programmed to compare the current operating conditions of the engine (102) with the current user requirements and to determine a desired supply flow rate ("m(dot)" or "mdot") at any given moment. Once the desired m(dot) flow rate is determined by the ECM (100), the ECM generates a corresponding m(dot) data signal representing the current m(dot) flow rate demand of the engine (102). Once the desired m(dot) flow rate is determined by the ECM (100), the corresponding m(dot) data signal is transmitted via communication links (196,197) to microcontrollers (930a,930b), which then control the large engine throttle (10) to supply fuel instantaneously and precisely from the throttle system outlet (170). Accordingly, according to one embodiment of the present disclosure, the controllers (930a,930b) are configured to determine a desired mass flow rate of fuel in the MFG (10).

[0086] After flow control by a large engine throttle (10), the controlled gas supply flow from the throttle system outlet (170) is led to a fuel-air mixer (161), where it is mixed with air (160) to produce a combustible fuel-air mixture (150). In a preferred embodiment, a filtered air (160) flow is used. In an alternative embodiment, the intake air (160) may be drawn from outside air, with or without a pressure compensator, although this may result in performance compromises. The fuel-air mixer (161) is preferably a venturi mixer or of another type that does not use moving parts in the supply flow, thereby maximizing durability and homogeneity of the fuel / air mixture under the flow conditions actually supplied to the combustion chamber (180). Most preferably, the fuel-air mixer (161) is of a form that includes a fuel ring, which helps to maintain the benefits of precise m (dot) flow control provided by the throttle system (10).

[0087] Once the fuel-air mixer (161) supplies the appropriate fuel-air mixture (150), the mixture (150) flows toward the engine (102). The fuel-air mixture (150) passes through the turbocharger (172). The turbocharger (172) takes in recirculated gas from the pre-turbo exhaust (171), mixes it with the fuel-air mixture (150), and compresses it. After leaving the turbocharger (172), the fuel-air mixture (150) passes through the turbo aftercooler (174). The turbo aftercooler (174) cools the fuel-air mixture (150) before it enters the engine (102). Reducing the temperature of the fuel-air mixture is necessary to allow for a higher density intake of air into the engine (102), and as a result, to increase the output of the engine (102). The post-turbo exhaust gas (173) passes through an oxygen sensor (190) and enters a three-way catalytic converter (TWC) (175). In other embodiments, the oxygen sensor (190) is located in the pre-turbo exhaust (171). As is well known to those skilled in the art, the TWC (175) reduces pollutants before the exhaust gas is released into the environment. Although not shown in the drawings, those skilled in the art will understand that preferred embodiments include a variety of other components. Furthermore, other components such as filters and safety valves are also not shown. With regard to such simplifications and omissions from the drawings, it should be understood that preferred embodiments include them in a manner and configuration that is generally understood within the discretion of those skilled in the art.

[0088] The flow of the fuel-air mixture (150) is controlled by a fuel-air throttle (140), which is preferably an electronic throttle, to further facilitate the maintenance of the high-precision flow control provided by the supply throttle (10) shown in Figure 10. Thus, the fuel-air throttle (140) is preferably composed of the same basic structure and software as the throttle (10), but may be modified to adapt to the different pressure ranges experienced downstream of the mixer (161), or to reduce the degree to which internal components are protected from the corrosive effects of higher fuel concentrations encountered upstream of the mixer (161). Since Figure 10 shows the throttle (10) being piped to control the mass flow rate of the fuel itself, this type of throttle use is sometimes called a mass flow gas throttle (MFG throttle). In contrast, a fuel-air throttle (140) used to control the mass flow of the fuel-air mixture (150) with high precision, whether or not the fuel is mixed with air, is sometimes called a mass flow air throttle (MFA throttle).

[0089] Preferably, the fuel-air throttle (140) is also constructed according to the teachings of this disclosure and has the same basic structure as the supply throttle (10) used as an MFG throttle to control the mass flow of fuel alone. Thus, the high-precision fuel supply flow by the MFG throttle (10) and the high-precision air supply mass flow control achieved by the MFA throttle (140) are preferably combined. Alternatively, complete and high-precision mass flow control can also be achieved by combining the MFG throttle with an MFA throttle piped to the air supply (160) upstream of the fuel-air mixer (161). Any of these combinations, as shown in Figure 10, or alternative combinations using similar throttles to control the mass flow of air (160) alone, enables comprehensive mass flow control of all supply flows for combustion. Furthermore, if the air mass flow is calculated using other reliable data (e.g., using an oxygen sensor combined with pressure, temperature, etc.), generally accurate control can be achieved overall without actively controlling the air mass flow. Regardless of which is chosen for a particular application, those skilled in the art will understand how to incorporate throttles to achieve overall mass flow control in different combinations for different purposes.

[0090] In either case, the resulting fuel-air mixture (150) is operationally introduced into the combustion chamber (180) of the engine (102) under the control of the controllers (930a, 930b). Within the combustion chamber (180), the fuel-air mixture (150) is spark-ignited, causing operational combustion.

[0091] Remarkably, the combined use of such MFG and MFA throttles dramatically streamlines the engine development cycle. Traditionally, large natural gas spark-ignition internal combustion engines required considerable time and expense to finalize and validate the engine design before commercialization. However, the high-precision mass flow control of this disclosure enables significantly simplified development without the need for test cell costs. While the industry will continue to use test cells to finalize the design, the precise control enabled by this disclosure not only greatly relaxes the standards in the development process but also enables extremely high-precision mass flow control even when fuel quality, air composition, and other environmental factors fluctuate significantly. [Determination of fuel characteristics]

[0092] In situations where the quality and composition of the fuel supplied to the engine are known and consistent, the fuel flow rate is measured and known, and the air flow rate is also measured or estimated along with other variables, the engine can be precisely tuned to achieve maximum output while complying with emission standards based on these measurements or estimates. However, in situations where the quality and / or composition of the fuel is unknown or fluctuates over time, the engine tuning process becomes difficult and often requires manual sensing to ultimately provide the precise mass flow rate of fuel based on the engine's requirements. The systems and methods of this disclosure can provide a significantly improved automatic tuning of the engine in such situations, based on the precise determination of the mass flow rate of air and the mass flow rate of fuel at any point during engine operation.

[0093] If the fuel composition fluctuates over time while being supplied to the engine (102), on-the-fly adjustments to maintain efficient operation and maximum power output of the engine (102) and compliance with emission standards can be difficult. To overcome this difficulty and to more efficiently adjust the engine on the fly, the two throttles shown and described herein can be used in a system configuration that provides the necessary data points for making real-time decisions to adjust or calibrate the engine based on fuel quality. To achieve this, a microcontroller for fuel supply (930a or 930b) (or an ECM (100) or other controller, or a group of controllers in an alternative embodiment) is programmed to estimate fuel quality characteristics using a process represented in the flowchart of Figure 11A and further described below.

[0094] According to at least some aspects of the system shown in Figure 10, two throttles are provided: a mass flow gas (MFG) throttle (20) and a mass flow air (MFA) throttle (140).

[0095] Figure 11A shows a simplified flowchart representative of a method used to estimate the fuel characteristics of a fuel supply, where the fuel supply has unknown fuel characteristics. In some embodiments, the method in Figure 11A is performed by either a controller (930a or 930b), and in other embodiments, it may be performed by an ECM (100). More specifically, Figure 11A shows the determination of the fuel mass flow ("MFG") in step (420) and the determination of the air mass flow ("MFA") in step (415). At the starting point (400), the air and gas mass flows are first determined (step (410)), and in step (415), the actual air mass flow is determined from a mass flow sensor located on the MFA throttle (140). In step (420), the actual gas mass flow is determined using an algorithm programmed into the microcontroller of the MFG throttle (20). In step (430), the oxygen level in the exhaust gas is read by the EGO sensor (190), and this step provides the actual air-fuel ratio, thereby determining the air-fuel ratio offset value. The process for determining the air-fuel ratio and other engine operation offset values ​​will be described later. The controllers (930a, 930b) (or other controllers in alternative embodiments, or a combination thereof) can determine the mass flow of both fuel and air using two throttles (10, 140) embodied in accordance with the teachings of this disclosure. The controllers (930a, 930b) determine the combustion result through monitoring of the oxygen sensor (190). In Figure 10, the oxygen sensor (190) is located in the exhaust manifold downstream of the MFA (140), preferably in the form of an exhaust oxygen sensor. Thus, the sensor (190) is positioned and configured to detect the oxygen content in the exhaust. The oxygen sensor (190) provides the controllers (930a, 930b) with a measurement of the oxygen concentration or deficiency in the gas. The oxygen level in the exhaust gas can be correlated with rich or lean air-fuel ratio characteristics. As is well known to those skilled in the art, the term "rich" refers to an air-fuel ratio in which there is more fuel than air, while the term "lean" refers to an air-fuel ratio in which there is more air than fuel.Regarding engine performance requirements, rich or lean air-fuel ratios may be desired to achieve specific load limits. Fuel quality can also influence whether the air-fuel ratio is rich or lean. Natural gas supplied directly from the wellhead has inconsistent chemical composition. Depending on the source, unrefined natural gas has characteristics related to the concentrations of its constituent gases. Typically, natural gas contains high concentrations of methane (CH4), but may also contain ethane (C2H6), propane (C3H8), butane (C4H10), pentane (C5H12), and hexane (C6H14). Lighter fuels such as methane may result in lower oxygen levels in the exhaust, while heavier fuels such as propane and ethane may result in higher oxygen levels in the exhaust. Note that such mass flow determination is performed by the throttle controller during the process of operating the throttle (20,140) in a preferred configuration illustrated in Figure 10. In step (440), fuel characteristics are interpolated based on the offset value. The feedback loop indicated by arrow (450) transmits the engine operation offset to each device so that the MFG throttle (10) and MFA throttle (140) are adjusted to match the engine requirements. In step (460), the fuel characteristics are estimated based on the method described with reference to Figure 11A and additional methods described later.

[0096] Figure 11B is a flowchart illustrating the method described in Figure 11A in more detail. As will be apparent from the following description, some of the methods described in Figures 11A and 11B may be referred to as fuel-air determination loops. In some embodiments, the method in Figure 11B is performed by controllers (930a, 930b), and in other embodiments, by the ECM (100). At the starting point (400'), the ECM (100) transmits a throttle angle position command or an air mass flow command to the MFA (140). In step (401), initial fuel characteristics and variables are assumed. Specifically, various assumed characteristics of the fuel supplied from the fuel tank (350) are programmed into the memory of the controllers (930a, 930b). In some embodiments, the characteristics stored in the controllers (930a, 930b) include the stoichiometric air-fuel ratio, the specific gravity of the fuel, and the specific heat ratio of air and fuel. In other embodiments, these fuel characteristics are stored in the ECM (100) and transmitted to the controllers (930a, 930b) via communication connections (196, 197). In some embodiments, as described later, the fuel in the fuel tank (350) is supplied directly from a natural fuel source, such as a natural gas well. In these embodiments, the various fuel characteristics of natural gas and other fuels are unknown because natural gas is supplied from a natural source largely untreated. Therefore, the fuel characteristics of natural gas are inconsistent and generally unknown. Accordingly, hypothetical fuel and air characteristics are programmed into the controllers (930a, 930b), which can use these to determine the mass flow rates of air and fuel flowing into the engine (102), and use these to determine specific fuel characteristics, as described later. Unlike fuel supplied to the internal combustion engine (102) from a natural source, the characteristics of ambient air are relatively certain and known, regardless of the source of the air. Therefore, when performing the various determinations and calculations described later to determine the mass flow rate of air, the assumed characteristic values ​​of the ambient air programmed into the controllers (930a, 930b) can be treated by the controllers (930a, 930b) as the true characteristic values ​​of the air supplied to the engine (102).

[0097] The air mass flow and fuel mass flow are calculated in step (404) by the controllers (930a,930b) based on the current inputs (403) from the MFG(10) and MFA(140) and the assumed fuel and air characteristics stored in the controllers (930a,930b) in step (401). First, as described above, the ECM(100) commands the air mass flow provided by the MFA(140). Next, based on the commanded air mass flow or the measured air mass flow passing through the MFA(140), as well as the target air-fuel ratio, the ECM(100) or controllers (930a,930b) calculates the desired mass flow rate of the fuel supply (350) and commands the MFG(10) to supply fuel at the desired mass flow rate. In order to provide a fuel supply at a desired mass flow rate, the controllers (930a, 930b) calculate the estimated mass flow rate of the fuel passing through the MFG(10) using various readings (403) from the MFG(10) and the assumed fuel characteristics stored in the controllers (930a, 930b). Specifically, the controllers (930a, 930b) calculate the estimated mass flow rate by adding pressure readings from pressure sensors (950a, 951a, 952a), temperature readings from the thermistor (600a), and / or position readings from the blade position sensor (940a) to the assumed fuel characteristics programmed in the controllers' (930a, 930b) memory. The controllers (930a, 930b) calculate the mass flow rate of the air passing through the MFA(140) in substantially the same manner as calculating the mass flow rate of the fuel passing through the MFG(10). As previously stated, the MFA(140) has substantially the same components and structure as the MFG(10), and is therefore configured to obtain the same pressure, temperature, and blade position readings for the air passing through the MFA(140) as the MFG(10) obtains for the fuel passing through the MFG(10). Looking at Figure 10, those skilled in the art will understand that it is not just air but a fuel-air mixture that passes through the MFA(140).Since the mass flow rate of fuel passing through the MFA(140) is calculated using readings from the MFG(10), the controllers (930a,930b) are configured to calculate the mass flow rate of air only passing through the MFA(140), taking into account the fuel passing through the MFA(140). In addition to input (403), offset correction values ​​applied to the actuators of the MFG(10) and MFA(140) (shown in step (430')) are also taken into consideration in determining the mass flow rates of air and fuel. In step (402), the true air-fuel ratio ("AF Ratio") is determined. The true air-fuel ratio is determined by the controllers (930a,930b) using the mass flow rates of air and fuel determined in step (404). In step (405), as described above, the ideal air-fuel ratio ("ideal AF ratio") is determined during the calibration of the internal combustion engine (102) based on the type of internal combustion engine (102) and catalytic converter used, and is pre-programmed into the ECM (100) or controller (930a, 930b) and used for various determinations and calculations described in more detail below.

[0098] In step (406), the percentage error of the air-fuel ratio is calculated by comparing the true AF ratio derived from block (402) with the ideal AF ratio derived from step (405). The offsets of MFG(10) and MFA(140) used in step (430') are determined in step (408). The determination of the offsets of MFG(10) and MFA(140) depends on input (407) based on measurements from oxygen sensor (190). Specifically, the readings from oxygen sensor (190) in step (407) are provided to controllers (930a, 930b) via CAN(195) and used for independent measurement of the true air-fuel ratio based on the oxygen concentration in the exhaust. If the air-fuel ratio result determined in step (402) and the AF ratio result from the oxygen sensor in step (407) are identical, the percentage error in step (409) should be 0%. On the other hand, if there is a difference due to a change in actual fuel characteristics that deviates significantly from the value entered in step (401), for example, the percentage error will be a value other than 0%. As described later, this percentage error forms the basis for the changes described in step (440'). If no correction is needed (indicated by the YES direction in step (409)), the fuel characteristics can be interpolated using the calibrated lookup table (referred to as the fuel table in step (440')) and the percentage error of the air-fuel ratio. In step (440'), the controllers (930a, 930b) execute the fuel characteristic determination and adjustment program, and the ECM (100) is configured to adjust the operation of the engine (102) based on the fuel characteristic value of the fuel supplied to the engine (102). This fuel characteristic value is determined by the controllers (930a, 930b) and sent to the EMC via the communication connections (196, 197). An example of a fuel characteristics determination and adjustment program is shown in Figure 11C, and the fuel table associated with the program is shown in Figure 12. The fuel characteristics can then be used as desired, as shown in step (460').For example, in some embodiments described in more detail below, in step (460'), the fuel characteristics determined by the controllers (930a, 930b) in step (440') are sent to a pump (1404) (see Figure 14) that pumps natural gas fuel from the natural gas well (1408), allowing the pump (1404) to pump the fuel more efficiently using the determined characteristics.

[0099] If correction is needed (indicated by NO in step (409)), the actuators of MFG(10) and MFA(140) must be adjusted (see step (430')), and the controllers (930a,930b) restart the fuel-air determination loop. For example, if the controllers (930a,930b) determine that the air-fuel ratio is rich by comparing the percentage error value in step (406) with the input from sensor (190) in step (407), the controllers (930a,930b) can control MFG(10) to limit the amount of fuel supplied and / or open MFA(140) to increase the amount of air mixed with the supplied fuel. Similarly, by comparing the percentage error value in step (406) with the input from sensor (190) in step (407), if the controller (930a,930b) determines that the air-fuel ratio is lean, the controller (930a,930b) can control MFG(10) to increase the amount of fuel supplied and / or throttle MFA(140) to decrease the amount of air mixed with the supplied fuel.

[0100] The controllers (930a, 930b) are connected to a database program containing calibrable manufacturer-recommended engine ratings. This database allows the controllers (930a, 930b) to access numerous manufacturer-recommended engine specifications. Further detailing the use of this database in this disclosure, there are specific fuel characteristics that the fuel supply should maintain to ensure optimized engine performance. To simplify the concept, a fuel with gasoline-like characteristics may negatively affect an engine designed to operate on a diesel-like fuel. Furthermore, gasoline and diesel may have various octane ratings associated with the level of engine performance improvement. The engines relating to this disclosure are designed to operate on natural gas and can be evaluated by methane number or BTU content, similar to octane rating. The fuel characteristics of the fuel supply can be compared to manufacturer-recommended fuel characteristics so that the controllers (930a, 930b) can calculate the relevant offset values. The stoichiometric air-fuel ratio is a theoretical value and can be used to calculate the theoretical gas mass flow if a known or estimated air mass flow is available. As is well known to those skilled in the art, a simple method for calculating the air-fuel ratio is to divide the estimated air mass flow by the gas mass flow. This practice is consistent with the ability of the controllers (930a, 930b) to instantaneously request a specific gas mass flow according to performance needs. To obtain the desired gas mass flow value, the controllers (930a, 930b) perform a percentage error analysis as shown in step (406) of Figure 11B to quantify how closely the actual air-fuel ratio matches the ideal air-fuel ratio. This analysis is used to determine how close the actual mass flow value is to the desired mass flow value, and the offset value shown in block (408) is determined. Depending on the offset value requested by the controllers (930a, 930b), the MFG throttle (10) is adjusted to satisfy that offset value. Similarly, the air mass flow is also determined and, if the MFA throttle (140) is located downstream of the MFG (10), provides the air mass flow to the controllers (930a, 930b). For the purposes of explaining the current disclosure, the mass flow of air is treated as a mathematically known or estimated constant, and therefore, the adjustment of MFA(140) is not explicitly described.However, the adjustment of the MFA(140) is within the scope of the capabilities of this disclosure. Note that the method for achieving the adjustment of the MFA(140) is the same as or similar to the method for achieving the adjustment of the MFG(10). Note that if the MFA throttle(140) is located downstream of the air intake and downstream of the fuel-air mixer(161) where air is mixed with fuel, the MFA(140) actually measures the mass flow of the air-fuel mixture, and therefore the mass flow of air is determined by subtracting the mass flow of fuel from the mass flow of the mixture. Nevertheless, in some alternative embodiments, a second throttle can be located in the air supply upstream of the fuel-air mixer(161) to directly determine and control the mass flow of air rather than the mixture.

[0101] As mentioned above, unrefined natural gas has discontinuities in its chemical composition, and if it is directly supplied from the wellhead to the engine at the site, the mismatch in fuel quality will result in unstable engine performance. In addition to performing the air-fuel ratio error analysis described in step (440'), the controllers (930a, 930b) also perform closed-loop error correction, which allows for the estimation of fuel characteristics. Closed-loop error correction is performed using the percentage error values ​​explained in step (440'). By utilizing closed-loop correction, accurate fuel characteristic values ​​such as "BTU content (BTU)" and "methane number (MN)" can be interpolated based on data included in the manufacturer's recommended engine rating database, such as the fuel table shown in Figure 12 and the response curve shown in Figure 13. The MFG(10) and MFA(140) precisely control the mass flow rates of air and fuel, allowing for the determination of accurate fuel characteristics. Therefore, since the mass flow rates of air and fuel are precisely controlled and known, the controllers (930a, 930b) can infer that the only reason the air-fuel ratio deviates from the ideal value is that the fuel characteristic value (e.g., BTU level) is different from the BTU level assumed when creating the hypothetical characteristic value stored in the controllers (930a, 930b) in step (401).

[0102] Focusing on Figure 11B—step (440')—fuel quality can be estimated from the air-fuel ratio closed-loop error correction generated by the controllers (930a, 930b). Assuming the engine is calibrated to operate with a specific fuel specification, fuel characteristics can be effectively interpolated from a table of characteristics known to be associated with the calculated error interval. For example, using a database program such as "GERP," step (420') accesses the engine manufacturer's recommended fuel specification and estimates fuel characteristics based on the closed-loop error. For example, if the engine is calibrated to operate with propane as the reference fuel, a closed-loop error will occur depending on the characteristics of the incoming fuel source. The closed-loop error determines the amount of correction required to achieve characteristics equivalent to the reference fuel. While this disclosure describes corrections made to the throttle positions of the MFG(10) and MFA(140), alternative embodiments may be applicable to corrections for other device settings.

[0103] As the feedback path (450) in Figure 11A suggests, it should also be understood that the fuel quality estimation can be iteratively improved by using the estimated fuel quality characteristics in determining the mass flow in the next step (410).

[0104] During normal engine operation, if measurements reveal a change in the air / fuel ratio from a desired ratio (rich, lean, or stoichiometric) based on a specific application, it can be expected that this change is due to either a change in the air or a change in the fuel. More specifically, in a given calibrated engine (102), a change in closed-loop correction is likely to be related to a change in airflow or a change in fuel flow / fuel characteristics. Since airflow for given rotational speeds and load conditions is now measurable, a change in closed-loop correction can be considered with higher accuracy to be due to a change in fuel characteristics. Therefore, characteristics related to airflow are less likely to change and can be monitored by the oxygen flow sensor (190). However, since the above parameters are known based on the configuration of the MFG throttle (20), MFA throttle (140), and oxygen sensor (190), it can be more accurately estimated that a change has occurred in the fuel, more specifically, a change in fuel composition or fuel characteristics. Multiple estimable fuel characteristics may exist based on known data related to the mass flow of fuel, the mass flow of air, and the air / fuel ratio. These fuel characteristics may include, but are not limited to, British Thermal Unit (BTU) content, Wobbe index, methane number, stoichiometric fuel / air ratio, fuel specific gravity, hydrogen / carbon ratio, fuel specific heat ratio, etc. While the following explanation specifically refers to BTU content, it should be understood that any of the listed fuel characteristics can be estimated. Furthermore, when "fuel characteristics" or "fuel quality" are used in general, this should be interpreted as a broad term encompassing any of the above fuel characteristics, as well as other fuel quality characteristics that characterize the quality of natural gas in the field of natural gas engines.

[0105] Given that the air mass flow, gas mass flow, and air / fuel ratio are known, the disclosed system (10) can estimate the BTU content of the gas. All these parameters are supplied to the ECM (100). Based on the known BTU content of the gas, the ECM (100) is programmed to automatically adjust specific engine settings to maintain efficient engine operation that yields appropriate output and preferably maintains compliance with applicable emission standards. For example, the φ target (before and after the catalyst), ignition timing, and / or maximum permissible load can be changed based on the BTU input. Furthermore, as another verification, the ignition timing can be adjusted and the knock level can be measured with a knock sensor (not shown). This helps to correlate the expected relationship between BTU content and methane number.

[0106] One common application where the above principles and system configurations are particularly beneficial is in engines incorporated into various applications of oil and gas fields. This includes, but is not limited to, generator packages driving bottom-well electric pumps, engines incorporated into gas compression systems, and other similar applications. For example, in certain applications of oil and gas fields, gas from a gas well can be supplied as fuel to an internal combustion engine. Because the composition of gas from a well fluctuates over time, its BTU content is usually unknown unless measured manually in the field using, for example, a gas chromatograph. In contrast, the systems and methods described herein have the ability to more accurately determine the BTU content of gas from a well based on information collected by the systems and methods described herein, without performing physical measurements. This represents a clear improvement when it is important to be able to distinguish between repurchased gas and sold gas based on gas composition, at least in part.

[0107] To elaborate further, in a typical system where gas from a well is supplied directly to an internal combustion engine, a person must physically go to the site to input specific setpoints for engine operation. This may involve measuring the gas, determining the gas's methane number, setting the ignition timing based on known information, and derating the engine based on all this information. Because the composition of gas from the well often fluctuates, it may be necessary for a person to make adjustments to the engine on-site to maintain engine operation in compliance with emission standards. By providing the systems and methods of disclosure, particularly the MFG throttle and MFA throttle that enable highly accurate measurement of fuel and air, the gas composition (BTU content) can be accurately estimated in this scenario, and adjustments to the internal combustion engine can be made without physical intervention.

[0108] In specific applications, if the system (10) estimates one or more fuel characteristics and a correction is required based on that determination, on-the-fly closed-loop correction can be performed on the fuel supplied to the engine (102). The fuel flow is measured and is a known value. The air / fuel ratio is determined using an oxygen sensor (190) and this value is transmitted to the controllers (930a, 930b). Therefore, the fuel flow and air flow are known. Alarm faults are set in the controllers (930a, 930b) to accurately determine whether a closed-loop correction is necessary. These alarm faults are calibrated. For example, a closed-loop correction value of 0 indicates that no intervention to change the fuel flow is required. However, a closed-loop correction value of minus 15 indicates that the system (10) needs to reduce energy, i.e., BTU content or fuel flow rate, by 15%. In other words, to maintain the desired output, the controllers (930a, 930b) command a 15% reduction in mass fuel flow to maintain the desired air / fuel ratio. In this example, the controllers (930a, 930b) can be set to a "plus / minus 15%" alarm fault. If the air / fuel ratio is indicated to be off by "plus / minus 15%", the controllers (930a, 930b) will command an increase or decrease in mass fuel flow to bring the air / fuel ratio back to the desired value. The fault alarm settings depend on the specific application in which the MFG throttle (10) and MFA throttle (140) are used. Furthermore, since the fuel mass flow, air mass flow, and air / fuel ratio are known, a closed-loop correction value, especially a non-zero value, can serve as an indicator to the operator that the fuel characteristics have changed.

[0109] Furthermore, another application of the system described herein is the precise use of large engine throttles solely as metering devices, for example, in gas pipelines. Large engine throttles offer high precision for flow measurement, and their application can replace more complex and / or expensive equipment and technologies, particularly in low-pressure applications such as large-diameter pipelines where the difference between upstream and downstream pressures is small.

[0110] Furthermore, another application in which the systems and methods disclosed herein may be beneficial is gas compression systems in oil and gas fields. More specifically, once fuel characteristic information is determined, the controllers (930a, 930b) can output this fuel characteristic information to a number of other important applications, as shown in step (460) of the flowchart in Figure 11A. For example, the fuel characteristic information can be transmitted to a compressor compressing the same natural gas supply system, which can be used for more accurate prediction and control of compressor power, as well as for a more accurate understanding of compressor and internal stage information. Turning to Figure 11C, a strategy for a “fuel characteristic determination and adjustment program” for determining fuel characteristics (fuel quality, load limit offset, φ offset, spark offset) is shown. Figure 11C further details the methods used to determine the concepts in Figures 11A and 11B. While Figure 11C explicitly describes how to determine fuel quality, load limit, φ offset, and spark offset, other characteristics (e.g., BTU content) can be determined in a similar manner. For ease of explanation, Figure 11C includes sections separated by square brackets for quick reference. The section indicated by bracket (1050) includes the process for determining the closed-loop error related to the air / fuel ratio of the fuel supply with unknown characteristics. The section indicated by bracket (1051) includes the interpolation method for determining fuel quality, ignition advance, and load limits.

[0111] Looking at the starting point (1000), the true air mass flow rate (1001) (indicated as mdot_a_i), determined from the mass flow sensor in the MFA throttle (140), is shown in box (1002). In various alternative embodiments, only one mass flow throttle may be used. Some of these alternative embodiments control the gas mass flow rate using the MFG, to the extent that the corresponding assumptions can be made for the air mass flow rate. In box (1003), the true air mass flow rate (1001) is divided by the true gas mass flow rate (indicated as 1 / mdot_g_i), based on the detected reading from the throttle control algorithm (990) (indicated in box (1002')) of the MFG throttle (10). The output of box (1003) is the true air-fuel ratio (1004) (indicated as AF_i). The true air-fuel ratio (1004) is subtracted from the ideal air-fuel ratio (1005) (indicated as AF_stck). The ideal air-fuel ratio (1005) is determined using the method shown in box (1028), where the values ​​and method are determined as part of the engine calibration process. Specifically, the ideal air-fuel ratio of an IC engine (102) is determined depending on the type of internal combustion engine (102) used and the specific catalytic converter paired with that engine (102). Thus, if the type of IC engine (102) and its catalytic converter are known, the ideal air-fuel ratio is known based on the calibration process performed in the test and is pre-programmed into the ECM (100) and / or controllers (930a, 930b) and used when the ECM (100) or controllers (930a, 930b) make the determinations and calculations described herein. The difference (1007) (denoted as ΔAF_i) between the true air-fuel ratio (1004) and the ideal air-fuel ratio (1005) is calculated. Next, as shown in box (1008), the air-fuel ratio difference (1007) is divided by the ideal air-fuel ratio and multiplied by 100 to obtain the percentage error value (1009). The percentage error value (1009) (indicated as ±e) is used to determine the fuel characteristics and the adjustment of the MFG throttle (20), as described later.The use of a percentage error value to determine throttle correction is called closed-loop correction, and its typical “loop” process is enclosed in a dashed box (1014). The percentage error is multiplied by the true air-fuel ratio (1004), as shown in box (1010), to obtain an air-fuel ratio adjustment value (1011) (indicated as + / -AF_adj). The air-fuel ratio adjustment value is transmitted to the throttle microcontroller (930). As previously mentioned, if the air mass flow rate is known, estimated, or kept constant, air-fuel ratio adjustment can be effectively performed by adjusting the mass flow rate of the gas. For the purpose of describing this disclosure in terms of simple inputs and outputs, the throttle control algorithm (990) is shown in Figure 11C as receiving the air-fuel ratio adjustment in the form of a requested mass flow rate value of the gas (1012) (indicated as mdot_g_0). The throttle control algorithm (990) correlates the required mass flow rate to a specific blade angle (1013) using a formula described later, and the MFG throttle (20) is adjusted accordingly.

[0112] Returning to the percentage error value (1009), this value is also used to determine the fuel characteristics. The percentage error value (1009) is related to the instantaneous air-fuel ratio. A calibrated lookup table (represented by box (1006)) is used to determine the fuel characteristics of the fuel supply, thereby interpolating the fuel characteristics. An example of a calibrated lookup table is shown in table (1200) in Figure 12. Calibration methods relating to this disclosure include determining the percentage error value associated with known fuel types. For example, if an engine is designed to run on propane, the calibration process includes running the engine with other fuel types whose characteristics are already known. As the fuel type moves further away from propane, a percentage air-fuel ratio error is associated with that fuel type. Propane has an error of 0%. Further explanation is given, if a fuel such as butane is used in the calibration process of an engine designed to run on propane, a percentage air-fuel ratio error is associated with butane. Outside of the calibration process, if the percentage error value (1009) lies between the values ​​for butane and propane, it is theoretically possible to interpolate the characteristics of an unknown fuel with some degree of accuracy. Thereafter, the percentage error value (1009) is entered into a calibrated lookup table. The result is used in a standard interpolation equation (shown in box (1018a)), where the variable y represents the fuel quality. Those skilled in the art will understand how to apply the equations shown in boxes (1018a), (1018b), and (1018c). This interpolation equation is used with other inputs to determine the engine's ignition timing (spark advance) (shown in box (1018b)) and load limits (shown in box (1018c)). Although not shown, the BTU content of the fuel supply is determined using the same or identical method as that used to determine the fuel quality. The equation shown in box (1018b) is used to solve for the required ignition timing. The inputs to equations (1018a), (1018b), and (1018c) are determined from the calibrated lookup table (1006), with the exception of the percentage error value (1009). The output of equation (1018b) is the adjustment of the ignition timing (1027) of the combustion chamber (180), which is required by the ECM (100).Those skilled in the art will understand that ignition timing refers to a combination of ignition timings related to piston position and crankshaft angle, and is also called the spark time sequence.

[0113] Focusing on the output of the equation in box (1018c), y represents the ideal load limit. The ideal load limit (1019) (denoted as LL_0) is used to determine the maximum blade angle of the MFA throttle (140). The method is shown in box (1024). The output of box (1024) is fed to the throttle algorithm (990) to ensure that the blade angle (1013') of the MFA throttle (140) does not exceed the maximum blade angle value. That is, the load limit of the internal combustion engine (102) is adjusted by the ECM (100) setting the maximum throttle blade angle of the MFA (140). By setting the maximum limit, the load limit of the IC engine (102) is limited by the amount of air introduced into the combustion chamber (180). For example, in one embodiment, in order to lower the load limit of the IC engine (102), the ECM (100) can adjust the MFA (140) to limit the amount of air introduced into the IC combustion chamber (180). In further embodiments, the ECM (100) can similarly impose a limit on the throttle blade angle of the MFG (10) in order to limit the load limit of the IC combustion chamber (180). As described above, in some embodiments, the controllers (930a, 930b) are configured to control the adjustments made to the engine (102), MFG (10), and MFA (140) based on the determined fuel characteristic values.

[0114] Returning to equation (1018a), the determined fuel quality (1025) of the fuel supply is used to determine or report (1034) the ideal φ value (1028). Fuel quality may be reported as BTU content or methane number. Figure 11C is intended to help illustrate the concepts of this disclosure, and methods for determining other relevant fuel properties are outside the scope of this description. [Fuel Quality Control Measures]

[0115] Referring to Figures 12 and 13, Figure 12 is a typical fuel table (1200) described in the previous calibration process example. Table (1200) is programmed into the controller (930a, 930b) or ECM (100), stored in the controller (930a, 930b) or ECM (100) memory, and used as a reference when running the fuel characteristic determination and adjustment program. Referring to the calibration example, the estimated closed-loop error and fuel characteristics associated with propane are shown in row (1201). If the system closed-loop error calculated by the controller (930a, 930b) or ECM (100) in step 406 above is between two known closed-loop errors (1203, for example), the rows above and below the system value are used to interpolate the desired fuel characteristics. Manufacturer specifications are shown in column (1202). In the example, a closed-loop error of 0% corresponds to an ideal BTU value of 900 BTU / scf and an ideal methane number of 98 MN, and in this ideal scenario, no adjustment of ignition timing and load limits by the ECM(100) is required. However, as shown in Figure 12, if the BTU and MN values ​​deviate from the ideal values, the ECM(100) adjusts the ignition timing and load limits in proportion to the amount of deviation. According to one embodiment, those skilled in the art will understand that columns 1 to 3 of table (1200) are stored in the controllers (930a, 930b) when calculating the BTU / MN numbers, and columns 4 and 5 are stored in the ECM(100), and that the ECM(100) adjusts the engine (102) based on the fuel characteristic information transmitted from the controllers (930a, 930b).

[0116] According to one embodiment, MN acts as a surrogate for the φ target (particularly the φ target after the catalytic converter), and as the MN number increases, the φ target increases from lean to rich. In other words, the minimum MN value corresponds to the leanest φ target, and the maximum MN value corresponds to the richest φ target. Thus, the ignition timing and load limits of the engine (102) can be adjusted based on the determined φ value to optimize emissions over a wide range of fuel compositions. Traditionally, when manufacturers certify an engine as EPA compliant, this has been done within a relatively narrow BTU input range. According to various embodiments of this disclosure, this range can be a wider BTU range compared to a typical engine BTU range.

[0117] The estimated BTU number can be used for a variety of applications. For example, according to one embodiment, the controller (930a, 930b) can be configured to estimate the fuel mixture of a fuel supply (350) based on the estimated BTU. Often, the fuel supply (350) is a mixture of two types of fuel, but the proportion of each fuel in the mixture is unknown. By using BTU, the proportion of each fuel in the mixture can be estimated. For example, in one embodiment, the fuel supply may be a mixture of natural gas and liquefied petroleum gas (LPG), and the controller (930a, 930b) can be programmed through adaptive learning to recognize that a BTU value of approximately 930 or less corresponds to 100% natural gas, a BTU value of approximately 1380 corresponds to 50 / 50 natural gas and LPG, and a BTU value of approximately 2300 corresponds to 100% LPG. Those skilled in the art will understand that this is just one of many examples for estimating the fuel mixture of a fuel supply (350).

[0118] Figure 13 shows the response curve (1300) used to determine the fuel quality of the fuel source. Depending on the load limit values ​​calculated using the interpolation method described earlier, the maximum load limit is associated with 100% to 75% natural gas (1303), where the fuel quality is reported to be 100 to 75. The minimum load limit is associated with 0% natural gas and 100% propane (1304). Since there is no slope between fuel quality 100 and 75, the load limit between points (1301) and (1302) results in observable fuel quality. Point (1301) is at 75% fuel quality, and point (1302) is at 0% fuel quality.

[0119] The fuel quality control function of this disclosure uses a database of controllers (930a, 930b) to determine simplified fuel quality data that may be useful to field personnel. The controllers (930a, 930b) are equipped with interactive software that allows technicians to input fuel characteristic values ​​for calibration. The software also allows for the operation mode of the controllers (930a, 930b). Depending on whether the fuel quality control function is in static or dynamic mode, the fuel quality data can also be used to determine the adjustments to the MFG throttle (20) or MFA throttle (140) necessary to maintain engine performance.

[0120] A common method for determining fuel quality from a natural gas well involves measuring BTU content and methane number, but inexperienced engineers and other personnel may have difficulty interpreting the measurement results. According to the teachings of this disclosure, fuel quality from a natural gas well can be expressed on a simple scale of 0 to 100%. The simplified response curve shown in Figure 13 illustrates the relationship between fuel quality and engine load limits. This 0 to 100 scale essentially represents the ratio of natural gas content to propane content in the fuel supply. Natural gas (NG) has a fuel quality of 100%, while liquefied propane gas (LPG) has a fuel quality of 0%. For example, a fuel quality reading of 25% indicates that the well produces fuel that behaves as a mixture of 25% natural gas and 75% propane.

[0121] The use of the fuel quality control function of this disclosure depends on the AFR closed-loop error offset value. The closed-loop error offset value is entered into a fuel calibration table as shown in Figure 12, and the values ​​of BTU content, AFR "φ", ignition advance angle, and fuel quality are interpolated by block multiplication. The interpolated values ​​are used to determine the offset value required by the ECM(100). A conceptual path for the interpolation of such values ​​is shown in Figure 11B. When the controllers (930a, 930b) are started, the BTU value of the reference fuel is used to initialize the system. The fuel quality control function is automatically activated when the supplied fuel is natural gas. However, if the type of supplied fuel is different or switched manually, the closed-loop error generated from the NG calibration remains constant. In other words, the fuel error adjustment remains relative to the NG characteristics.

[0122] As mentioned above, the fuel quality control function can operate in dynamic or static mode. When dynamic mode is enabled, a closed-loop error offset value is used to initialize the fuel table block multiplier of the controller (930a, 930b), and the BTU content and MN are continuously updated based on the mass flow rate readings provided by MFG(10) and MFA(140). The manufacturer-recommended ignition / φ / load limit interpolations calculated from the updated BTU content and MN are used to automatically adjust the associated equipment. When static mode is enabled, the controller (930a, 930b) is initialized in the same way as in dynamic mode, but the BTU content, MN, and manufacturer-recommended ignition / φ / load limit values ​​remain constant relative to the reference fuel. In static mode, equipment adjustments are made based on a one-time system initialization determined by the reference fuel characteristics, and no adjustments are made relative to the well fuel quality. The application of static mode is useful when the characteristics of the fuel source are determined and used as the reference fuel for calibration. For example, natural gas wells in the Permian Basin in Texas, USA, and natural gas wells in the Eagle Ford Formation, supply different quality fuels. In this context, system calibration can be performed based on geographical fuel supply.

[0123] When the methane number fuel trim function is enabled, the air-fuel ratio, or "φ", can be adjusted as needed. In dynamic mode, φ is adjusted based on the MN interpolated using the closed-loop error value and the fuel calibration table. If the interpolated MN is greater than or equal to the MN associated with the manufacturer's recommended ignition / φ specification, φ is adjusted. The adjusted φ value generated by this system is used to correct the mass flow rate of gas or air. The correction value is requested from the controller (930a, 930b) for each throttle of MFG(10) and MFA(140). In static mode, the interpolated MN value of the fuel source can simply be referenced from the fuel calibration table.

[0124] The ignition advance angle value is controlled by the aforementioned database program compensation mode. When this database program is activated, the manufacturer-recommended ignition advance angle, φ, and load limit values ​​are used by the controller (930a, 930b). The database program interpolates the ignition advance angle value from the fuel table using a closed-loop error input. Once the ignition advance angle is determined, the adjustment offset amount applied by the ECM(100) and the resulting ignition advance angle can be observed.

[0125] The above method for determining the ignition advance angle is only valid when the fuel quality control system is enabled. If the fuel quality control system is not enabled, the database program determines the ignition advance angle based on a previously calibrated range of 0-100%. Natural gas has a database program value of 0%, while liquefied propane gas has a value of 100%. The percentage value in the database program depends on whether the fuel supply behaves more like natural gas or propane.

[0126] To control the engine load limit, the fuel type may be set to NG, and the fuel quality control system may be activated. The load limit is also determined using the fuel table interpolation method. The closed-loop error is input, and the load limit is interpolated based on the manufacturer's recommended value for the engine load limit. Once the load limit is determined, the fuel quality is determined by the interpolated value based on the response curve shown in Figure 13. [Throttle control measures]

[0127] As will be understood by those skilled in the art, the following mass flow equations are used to describe the non-choke flow of a gas through an orifice. Equation (1) is the mass flow equation for an ideal gas, and equation (2) uses the gas compressibility coefficient "Z" to correct for the mass flow of a real gas.

[0128]

number

[0129]

number

[0130] In this formula, m (dot) is the desired mass flow rate required by ECM(100), "C" is the dimensionless orifice flow coefficient, "A2" is the cross-sectional area of ​​the orifice hole ("effective area"), "ρ1" is the upstream actual gas density, "P1" is the upstream gas pressure, "k" is the specific heat ratio, "P2" is the downstream gas pressure, "M" is the molecular mass of the gas, "T1" is the upstream absolute gas temperature, "Z" is the dimensionless gas compressibility coefficient at "P1" and "T1", and "R" is the universal gas constant. The values ​​of "Z" and "R" are specific to a particular gas, or in this disclosure, a particular fuel type. These values ​​can be kept constant with respect to the calibration reference fuel. The value of "C" is determined using the pressure difference "ΔP" in the MFA or MFG throttle valve.

[0131] Referring to Figure 10, the throttle control algorithm (990) uses equation (2) to determine the A2 "effective area" required to achieve the desired m (dot) mass flow rate. The algorithm essentially modifies equation (2) to calculate the effective area and correlates it with the throttle blade angle. P2, P1, and T1 are measured as described above, and these values ​​are used in equation (2). Corrections to the mass flow rate can be correlated with the "effective area" correction required to achieve the desired mass flow rate. The microcontroller (930) constantly uses the throttle control algorithm (990) to obtain the accurate m (dot) flow rate while the parameters are changing. Once the A2 "effective area" is determined by the throttle control algorithm (990), a signal is sent to the brushless motor (700). The brushless motor (700) is an actuator that controls the movement of the throttle shaft (710) to adjust the throttle blade (210) and achieve the desired "effective area" A2 of the gas supply throttle (20). The brushless motor (700) is preferably a high-speed actuator, and preferably capable of moving the throttle blade (210) over its entire operating range in 50 milliseconds or less. The high-speed actuator is preferably capable of moving the actuating element over most of its operating range (preferably 20% to 80%) or over its entire range in 50 milliseconds or less. However, many other types of actuators are still applicable as alternatives, in particular unless a specific claimed element is explicitly denied as requiring a specific high-speed operating characteristic. [Operating pressure - low pressure]

[0132] While it is understood that adaptation to other upstream conditions is possible, it is preferable that the pressure in the supply line (376) at the supply inlet (390) be controlled by a mechanical pressure regulator (370) to a gauge pressure slightly higher than atmospheric pressure. However, when the throttle (10) is used as an MFG throttle, the pressure may be higher up to 2.5 bar absolute pressure, and up to 4 bar absolute pressure in MFA applications.

[0133] While not essential for highly precise mass flow control, some aspects of the control method for a large engine throttle (10) may be further tuned to achieve desired control based on actual or estimated fluid conditions, and further downstream conditions. For example, a downstream sensor (121) may monitor pressure (designated as "P3" in this disclosure), which is monitored by an ECM (100) and made continuously available from a controller (930, 930b) or associated data network. A specific P3 value from the sensor (121) represents an available data stream characterizing the pre-combustion fluid pressure in the engine (102). Such a downstream sensor (121) may be a conventional temperature-manifold absolute pressure (TMAP) sensor module located in the engine's intake manifold downstream of the fuel-air throttle (140). In addition to, or as an alternative to, a conventional TMAP sensor (121), downstream data may also be obtained from a conventional throttle inlet pressure (TIP) sensor module located upstream of the fuel-air throttle (140). Although there are certain advantages to understanding P3, in many preferred embodiments, the consideration of P3 data from sensor (121) is omitted as unnecessary, opting for simplification and cost reduction. [Alternative fuel]

[0134] In this specification, “gaseous fuel” means a fuel that is in a gaseous state at standard operating temperatures and pressures. In the currently preferred embodiments, the gaseous fuel is natural gas, obtained from liquefied natural gas (LNG) or compressed natural gas (CNG) in storage. While these fuels are most preferred for use, those skilled in the art will see adaptations for applying embodiments of this disclosure to other fuels. Such alternative embodiments are adapted for use with, for example, hydrogen, other gaseous fuels (such as propane and butane), and gas mixtures common to liquefied petroleum gas (LPG) mixtures. Indeed, although this disclosure focuses on specific fields in which preferred embodiments are applied, some embodiments may be considered innovative in other fields as well. [Usage patterns of the power system]

[0135] Figure 14 shows a hydrocarbon recovery system (1400) utilizing the power unit system (1402) described above. Specifically, the engine (102) of the system (1402) is operationally connected to a pump (1404) by a shaft (1406) and supplies power to the pump (1404). The pump (1404) is configured to pump hydrocarbons from a natural hydrocarbon source (1408) through a source line (1409). Specifically, in some embodiments, the hydrocarbon source (1408) is a natural gas well located underground, and the pump (1404) is configured to pump natural gas from the well (1408). Those skilled in the art will understand that the hydrocarbon source (1408) may be a well or other natural hydrocarbon source, but throughout this specification, the hydrocarbon source (1408) refers to the natural gas well from which the pump (1404) pumps natural gas.

[0136] A pump (1404) is configured to deliver natural gas from a well (1408) to a destination (1410), supplied through a destination line (1412). Those skilled in the art will understand that the destination (1410) may be any of several points within the natural gas recovery system (1400). For example, in some embodiments, the destination (1410) is a storage tank that stores natural gas from the well (1408). In other embodiments, the destination (1410) is a facility that purifies natural gas from the well (1408). Furthermore, in some embodiments, the pump (1404) is also configured to deliver natural gas through a supply line (1414) that supplies fuel to a power system (1402) to supply fuel to an engine (102). For example, in some embodiments, the supply line (1414) is connected to a fuel tank (360) and is configured to maintain a constant natural gas fuel level in the fuel tank (360) and to supply fuel to the engine (102). Therefore, in some embodiments, the fuel tank (360) may be filled with a small amount of “starting fuel” to start the engine (102) and operate the pump (1404). Once the pump (1404) is started, the natural gas fuel level in the fuel tank (360) is adequately maintained by the pump (1404) supplying natural gas from the well (1408).

[0137] In some embodiments, the pump (1404) further includes a pump control module (PCM) (1416) configured to control the operation of the pump (1404). The PCM (1416) is configured to communicate with controllers (930a, 930b) by wired or wireless means. As described above, the controllers (930a, 930b) transmit various determination results to the PCM (1416), which can use these determination results to more efficiently control the operation of the pump (1404). For example, in some embodiments, in step 460' of the method described in Figure 11B, the controllers (930a, 930b) are configured to transmit estimated fuel characteristics to the PCM (1416). As described above and in detail with reference to Figures 11A-13, the controllers (930a, 930b) are configured to determine specific fuel characteristic values ​​(e.g., BTU values) of the natural gas passing through the MFG (10). Referring to Figure 14, the gas supplied to MFG(10) is ultimately natural gas drawn by pump (1404) from well (1408). Therefore, controllers (930a, 930b) are configured to determine the BTU value of the natural gas in well (1408). Since PCM(1416) has access to the BTU value of the natural gas in well (1408), PCM(1416) can control pump (1404) based on characteristic values ​​(e.g., BTU value) received from controllers (930a, 930b). Those skilled in the art will understand that it is desirable to know the characteristics of the fuel to be pumped by pump (1404). This is so that the settings and operation of pump (1404) can be adjusted to pump the natural gas most efficiently. [Throttle body assembly (20) and annular sensing ring]

[0138] According to various embodiments of the present disclosure, the throttle body assembly (20), as previously described in detail, further includes annular sensing rings (1500, 1510), which further improve the accuracy of the pressure sensors (950-952). Figures 15A and 15B show perspective views of the downstream and upstream sides of the throttle body assembly (20), respectively. The upstream sensing ring (1500) is positioned upstream of the valve body (22) in the flow path hole (24), and the downstream sensing ring (1510) is positioned downstream of the valve body (22) in the flow path hole (24). As will be described in more detail below, the rings (1500, 1510) form an annular space between the outer circumference of each ring and the flow path hole (24), and are configured such that the fluid passing through the flow path hole (24) fills these annular spaces. The pressure ports (230, 240) are in fluid communication with these annular spaces, and therefore the sensors (950-952) can read the pressure from the fluid in the annular spaces rather than from the fluid flowing directly through the flow holes (24), enabling pressure measurement with less position dependence.

[0139] Figure 16A shows a perspective view of the upstream sensing ring (1500). The sensing ring (1500) has a shoulder portion (1502) that fits into the flow path hole (24) and a recessed portion (1504) having an outer diameter smaller than the outer diameter of the shoulder portion (1502). Furthermore, the sensing ring (1500) has multiple notches (1506) formed on its outer edge (1504), which allow the fluid passing through the flow path hole (24) to flow between the sensing ring (1500) and the annular space formed between the sensing ring (1500) and the wall of the flow path hole (24).

[0140] Figure 16B shows a perspective view of the downstream sensing ring (1510). The sensing ring (1510) has a shoulder portion (1512) that fits into the flow path hole (24) and a recessed portion (1514) having an outer diameter smaller than the outer diameter of the shoulder portion (1512). Furthermore, the sensing ring (1510) is provided with a plurality of through holes (1516) in the recessed portion (1514), which allow the fluid passing through the flow path hole (24) to flow between the sensing ring (1510) and the annular space formed between the wall of the flow path hole (24).

[0141] Figure 17 shows a cross-sectional view of the throttle body assembly (20) with the sensing rings (1500, 1510) mounted in the flow path hole (24). Specifically, the sensing ring (1500) is mounted on the upstream sensing ring seat (1530) of the flow path hole (24). As described above, when the sensing ring (1500) is placed on the seat (1530), the wall of the seat (1530), the outer wall of the recessed portion (1504), and the end wall of the shoulder portion (1502) facing downstream form an upstream annular space (1520). Fluid passing through the flow path hole (24) flows into and out of the annular space (1520) through the notch (1506) and the opening formed in the seat (1530). As shown in the figure, the sensor support (230) is in direct fluid communication with the upstream annular space (1520).

[0142] The sensing ring (1510) is mounted on the downstream sensing ring sheet (1532) of the flow path hole (24). As described above, when the sensing ring (1510) is placed on the sheet (1532), the wall of the sheet (1532), the outer wall of the recessed portion (1514), and the end wall of the shoulder portion (1512) facing the upstream side form a downstream annular space (1522). The fluid passing through the flow path hole (24) flows into and out of the annular space (1522) through the through hole (1516). As shown in the figure, the sensor support (240) is in direct fluid communication with the downstream annular space (1522).

[0143] Those skilled in the art will understand the benefit that the annular space (1520, 1522) provides to the sensors (950-952). Specifically, the annular space (1500, 1520) forms a relatively "static" pocket of working fluid, providing a uniform pressure gradient that enables the sensors (950-952) to take measurements. Without the sensing ring (1500, 1510), pressure measurements are taken from the fluid passing directly through the flow path hole (24), and because a non-uniform pressure gradient exists across the entire flow path cross-section, position dependence occurs, and it may not be possible to accurately represent the pressure of the fluid passing through the flow path hole (24).

[0144] Although the sensing rings (1500, 1510) are shown as distinct from each other, those skilled in the art will understand that in other embodiments the upstream and downstream sensing rings can be identical. Furthermore, in one embodiment the upstream sensing ring (1500) has a through hole (1516), and in another embodiment the downstream sensing ring (1510) has a notch (1506). In yet another embodiment the rings (1500, 1510) can have different types of passages that allow fluid communication with the annular spaces (1520, 1522). Although not depicted in the cross-section shown in Figure 17, those skilled in the art will understand, by referring to Figure 2D, that in one embodiment the temperature sensor support (250) also has fluid communication with the annular space (1520). Also, in another embodiment, they will understand that the port (250) also has fluid communication with the annular space (1522). [Other alternatives]

[0145] The above description and drawings will enable a person skilled in the art to construct and use the best mode of this disclosure, but should not be illustrative and limiting in any respect. A person skilled in the art will understand and appreciate that countless modifications, changes, variations, combinations, rearrangements, substitutions, alternatives, design choices and equivalents (hereinafter, "Alternatives") exist without departing from the spirit and scope.

[0146] Accordingly, this disclosure is not limited to the embodiments and examples described, but rather encompasses all embodiments contained within the scope and spirit of the claims, taking into consideration that claims may be modified, replaced, or otherwise altered during the relevant examination process. Current, modified, or added claims should be interpreted to encompass all further modifications, changes, rearrangements, replacements, alternatives, design choices, and embodiments, including those that are obvious to those skilled in the art and those that are discovered later. For example, another alternative related to this disclosure is the use of a single mass flow throttle, where a mass flow throttle controlling the mass flow rate of the air-fuel mixture may be used, which for convenience may be referred to as MFA / MFG. Furthermore, other alternatives will also be obvious to those skilled in the art. In any case, equivalents should be considered to be included within the scope of this disclosure, except to the extent that they are expressly abandoned during the examination process or that are necessary to maintain the validity of a particular claim in light of the prior art. [Explanation of Symbols]

[0147] 1 System 10. Large engine throttle (MFG throttle) 10' Large engine throttle (modified version) 20. Throttle Body Assembly (Gas Supply Throttle) 22 Throttle Body 24 Flowing hole (bore) 30 Inlet Adapter 31-34 Inlet adapter fixing screws Nuts compatible with 31a~34a 35 Seals (for inlet adapters) 40 Outlet Adapters 41-44 Screws for fixing the outlet adapter Nuts compatible with 41a~44a 45 Seals (for outlet adapters) 50 Spring Assembly 50' Spring Assembly (Variation) 510 Throttle Shaft Seal 511 Seal Spacer 512 Seal retainer washer 513 Bearing Assembly 520 wave spring 521 (Free spring: Related to variations) 530 Spring return flange 531 Pin (center of spring return flange) 540 O-rings (for spring assemblies) 550 Spring Return Cover 551-554 Spring return cover fixing screws 60 Thermistor Assembly 600 Thermistor 601 Thermistor tip (sensor tip) 602 Thermistor base 610 Thermistor PCB 611,612 Lead wires 620 Epoxy Overmold 630 Thermistor Tube 640 Thermistor Fixing Screw 70 Motor Throttle Shaft Assembly 700 Brushless Motor 701-704 Fixing screws 710 Throttle Shaft 711 Throttle shaft seal (with insert) 712 Seal Spacer 720 rotor arm 730 Rotor arm fixing screw 740 Permanent Magnets 80 Intermediate Housing Assembly (Motor Enclosure) 800 Intermediate Housing 810 Motor storage space 820 CAN pin connector opening 830 Backflow check valve housing 840 Backflow Check Valve 850 Forward flow check valve housing 860 Forward flow check valve 870 Seal (In-groove type) 90 Printed circuit board (PCB) assemblies 900 PCB (Printed Circuit Board) 901 PCB Housing Cover 902 Seal (for PCB housing) 903-914 PCB fixing screws 915-920 PCB Assembly Fixing Screws 930 Microcontroller 930a, 930b Microcontrollers (for each throttle) 940 Blade Position Sensor Assembly 941a~941e Hall effect sensor 950 Differential pressure sensor (ΔP sensor) 951 Upstream pressure sensor (for P1) 951a Upstream pressure sensor gasket 952 Downstream pressure sensor (for P2) 953 Downstream pressure sensor gasket 955,956 Differential pressure sensor gasket 99 Unitary Block Assembly 99' Unitary block assembly (modified version) 100 Engine Control Module (ECM) 102 Engine 140 MFA throttle (fuel-air throttle) 170 Supply Outlets 180 Combustion Chamber 190 Oxygen Sensor (EGO Sensor) 195 CAN network 196,197 Communication lines 200 Throttle Orifice 205 Throttle Chamber 210 Throttle Blade 220,221 cooling ports 230 Pressure port (upstream side) 240 Pressure port (downstream side) 250°C Temperature Sensor Support 260' Alternative air-mix flow arrow 350 fuel supply 360 Fuel Tank 365,375,376 Fuel supply lines 370 Mechanical Pressure Regulator 380 Fuel shut-off valve (gate valve) 400~460' Fuel Characteristics Determination Flowchart Process Number 700 Brushless Motor Element numbers 1000-1036 in the flowchart (Figure 11C) 1200 Fuel Calibration Table (Figure 12) 1300 Response curve (Figure 13) 1400 Hydrocarbon Recovery System 1402 Power Unit System 1404 Pump 1406 Shaft 1408 Hydrocarbon source (natural gas well) 1409 Source Line 1410 Destination (storage facility or refining facility) 1412 Destination Line 1414 Fuel supply line 1416 Pump Control Module (PCM) 1500 Upstream Sensing Ring 1502 Shoulder section (upstream sensing ring) 1504 Recess section (upstream sensing ring) 1506 Notch 1510 Downstream Sensing Ring 1512 Shoulder section (downstream sensing ring) 1514 Recess section (downstream sensing ring) 1516 Through-hole 1520 Upstream annulus 1522 Downstream Annulus 1530 Upstream Sensing Ring Sheet 1532 Downstream Sensing Ring Sheet

Claims

1. A system for determining the fuel characteristics of fuel supplied to an internal combustion engine and controlling the mass flow rate of the fuel-air mixture supplied to the internal combustion engine, A fuel control valve configured to control the fuel supplied from a fuel source to the internal combustion engine, the fuel control valve includes a fuel controller that controls its operation, An air control valve configured to control the air supplied to the internal combustion engine, the air control valve includes an air controller that controls its operation, The engine control module (ECM) of the internal combustion engine, Equipped with, The air controller and the fuel controller, or one or both, are the calculation controllers of the system, and the calculation controllers are To measure the input mass flow rate to the internal combustion engine (the mass flow rate of the mixture of fuel and air), Based on the current measurement of the mass flow rate, determine the current air-fuel ratio of the mass flow rate. To determine the target air-fuel ratio of the internal combustion engine, The error measurement is calculated based on the difference between the current air-fuel ratio and the target air-fuel ratio. Execute a fuel characteristic determination program that determines the fuel characteristic corresponding to the error measurement by interpolating based on known fuel characteristics and corresponding error measurement values. The fuel characteristics are transmitted to the ECM in order to operate the internal combustion engine based on the characteristics of the fuel. The aforementioned ECM is The characteristics of the fuel are received from the calculation controller. The operation of the internal combustion engine is controlled based on the characteristics of the fuel. system.

2. The fuel control valve further includes a plurality of fuel pressure sensors that measure pressure from the fuel flow path, and a fuel temperature sensor that measures temperature from the flow path. The system according to claim 1, wherein the estimated fuel characteristics are stored in the fuel controller, and the fuel controller is configured to calculate a throttle opening to obtain a desired fuel mass flow rate using the estimated fuel characteristics and measurements from the plurality of fuel pressure sensors and the fuel temperature sensor.

3. The air control valve further includes a plurality of air pressure sensors that measure pressure from the airflow path, and an air temperature sensor that measures temperature from the airflow path. The system according to claim 1, wherein the properties of the air are stored in the air controller, and the air controller is configured to calculate the mass flow rate of the air using the properties of the air and the measurements from the plurality of air pressure sensors and the air temperature sensor.

4. The system further includes an oxygen sensor for measuring the oxygen concentration of the exhaust gas of the internal combustion engine. The aforementioned arithmetic controller, Receiving the measured value of the oxygen concentration, and determining the correction of the fuel control valve and / or the air control valve based on the measured oxygen concentration and the error measured value, The system according to claim 1, comprising the above configuration.

5. The system according to claim 4, wherein two or more of the fuel controller, the air controller, the oxygen sensor, and the ECM of the internal combustion engine are configured to communicate with each other via a communication network.

6. The operation of the internal combustion engine includes ignition advance, and the ECM is, The target ignition advance angle corresponding to the characteristics of the aforementioned fuel is determined by interpolation based on known fuel characteristics and the corresponding ignition advance angles. and controlling the ignition advance angle of the internal combustion engine to achieve the target ignition advance angle, The system according to claim 1, comprising the above configuration.

7. The operation of the internal combustion engine includes load limits, and the ECM is, The target load limit corresponding to the characteristics of the aforementioned fuel is determined by interpolation based on known fuel characteristics and their corresponding load limits. and controlling the load limit of the internal combustion engine to achieve the target load limit, The system according to claim 1, comprising the above configuration.

8. The system according to claim 1, wherein the ECM is configured to adjust the operation of the internal combustion engine if the fuel characteristics require adjustment of the operating conditions of the internal combustion engine.

9. The system according to claim 8, wherein the ECM is configured to adjust the operation of the internal combustion engine to achieve a target φ value for the internal combustion engine.

10. The system according to claim 1, wherein the fuel characteristics include one or more British calorific value (BTU), methane number (MN), or φ value.

11. The system according to claim 1, wherein known fuel characteristics corresponding to the error measurement values ​​are stored in a fuel characteristics database, and the calculation controller is configured to store the fuel characteristics database.

12. The system according to claim 1, wherein the system is calibrated using a calibration method, a fuel characteristics database is generated in the calibration method, and the fuel characteristics database includes known fuel characteristics corresponding to the error measurement values.

13. The system according to claim 1, wherein the system is calibrated using a calibration method, a fuel characteristics database is generated in the calibration method, and the fuel characteristics database includes known fuel characteristics corresponding to the operating parameters of the internal combustion engine.

14. The system according to claim 13, wherein the operating parameters include the ignition advance angle and load limit of the internal combustion engine corresponding to the known fuel characteristics.

15. The system according to claim 14, wherein the fuel characteristics database is stored in the ECM.

16. The system according to claim 1, wherein the measurement of the input mass flow rate includes one or both of the mass flow rate of the air and / or the mass flow rate of the fuel.

17. The system according to claim 1, wherein the target air-fuel ratio of the internal combustion engine is determined based on the type of the internal combustion engine and a catalytic converter combined with the internal combustion engine.

18. The ECM transmits engine operation data to the calculation controller. The aforementioned arithmetic controller, Receiving the aforementioned engine operation data, and to determine whether the operating conditions of the internal combustion engine are suitable for determining fuel characteristics. The system according to claim 1, comprising the above configuration.

19. A method for determining the fuel characteristics of fuel supplied to an internal combustion engine and controlling the mass flow rate of a fuel-air mixture supplied to the internal combustion engine, The input mass flow rate to the internal combustion engine (mass flow rate of the fuel-air mixture) is measured by a calculation controller, wherein the calculation controller is either a fuel controller of a fuel control valve, which includes a fuel controller configured to control the fuel supplied from the fuel source to the internal combustion engine and controls its operation, or an air controller of an air control valve, which includes an air controller configured to control the air supplied to the internal combustion engine and controls its operation, or both. Based on the current measurement of the mass flow rate, determine the current air-fuel ratio of the mass flow rate. To determine the target air-fuel ratio of the internal combustion engine, The error measurement is calculated based on the difference between the current air-fuel ratio and the target air-fuel ratio. Execute a fuel characteristic determination program that determines the fuel characteristic corresponding to the error measurement by interpolating based on known fuel characteristics and corresponding error measurement values. and transmit the fuel characteristics to the engine control module (ECM) of the internal combustion engine, enabling the ECM to operate the internal combustion engine based on the fuel characteristics. A method that includes this.

20. The ECM receives the fuel characteristics from the calculation controller. and controlling the operation of the internal combustion engine based on the fuel characteristics, The method according to claim 19, further comprising:

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