Control system for a dual-fuel engine

Abstract

Control system for a dual-fuel engine (10), comprising: a gaseous fuel injector (38) having a nozzle head (54) arranged at the first air inlet port (32) of a cylinder (16) of the engine (10) and configured to inject a variable quantity of gaseous fuel radially into the cylinder (16) based on at least either a load and / or a speed of the engine (10); a liquid fuel injector (36) configured to inject a fixed quantity of liquid fuel axially into the cylinder (16) based on at least either the load and / or speed of the engine (10); a governor (57) configured to selectively adjust the flow of gaseous fuel to the gaseous fuel injector (38);at least one sensor (53) arranged at a second air inlet port (32) of the cylinder (16) and configured to generate a first signal indicating a first performance parameter of the engine (10), wherein the first performance parameter is the presence of gaseous fuel exiting the cylinder (16) through the second air inlet port (32); and a control unit (55) connected to the regulator (57) and the at least one sensor (53), wherein the control unit (55) is configured to selectively cause the regulator (57) to adjust the flow of gaseous fuel based on the signal.

Description

Technical field

[0001] The present disclosure relates to a control system and in particular a control system for a dual-fuel engine. background

[0002] Due to the rising cost of liquid fuel (e.g., diesel) and ever-increasing restrictions on exhaust emissions, engine manufacturers have developed dual-fuel engines. A typical dual-fuel engine provides injections of a cost-effective gaseous fuel (e.g., natural gas) through the engine's cylinder air intake ports. The gaseous fuel is introduced along with clean air entering through the intake ports and ignited by liquid fuel injected during each combustion cycle. Because a less expensive fuel is used in conjunction with liquid fuel, cost efficiency can be improved. Furthermore, the combustion of the gaseous and liquid fuel mixture can lead to a reduction in harmful emissions.

[0003] In these dual-fuel engines, particular attention can be paid to the pressures, flow rates, and timing of the gaseous and liquid fuels injected into the cylinders. If these parameters are not closely controlled, the engine may not deliver its expected performance.

[0004] An exemplary control system for a dual-fuel engine is disclosed in U.S. Patent No. 4,527,516, granted to Foster. Specifically, the 516 patent discloses a dual-fuel engine comprising an intake pipe connected at one end to a gas source and at the opposite end to a side of an engine cylinder via an intake port. The 516 patent also includes an electronically controlled gas intake valve for timing the gas intake into the cylinder through the intake pipe. The gas intake valve controls a parameter of the gas flow to meet engine requirements but does not rely on feedback for control purposes. Instead, the valve provides only forward control to meet given fuel specifications.

[0005] Although it may be suitable for some applications, the control system of the 516 patent may not be optimal in certain circumstances. In particular, because the control system only includes forward control, it cannot account for fluctuations in environmental factors and / or aging-related factors that may affect system performance.

[0006] The disclosed control system aims to overcome one or more of the problems outlined above and / or other problems in the prior art. Summary

[0007] According to one aspect, the present disclosure relates to a control system for a dual-fuel engine. The control system may include a gaseous fuel injector having a nozzle head arranged at the first air intake port of a cylinder of the engine and configured to inject a variable quantity of gaseous fuel radially into the cylinder based on at least one engine load and / or speed. The control system may also include a liquid fuel injector configured to inject a fixed quantity of liquid fuel axially into the cylinder based on at least one engine load and / or speed.The control system may additionally include a regulator configured to selectively adjust the flow of gaseous fuel to the gaseous fuel injector, and at least one sensor configured to generate a signal indicating an engine performance parameter. The control system may also include a control unit that communicates with the regulator and the at least one sensor. The control unit may be configured to selectively instruct the regulator to adjust the flow of gaseous fuel based on the signal.

[0008] According to a further aspect, the present disclosure relates to a method for controlling the operation of a dual-fuel engine. The method can include injecting a variable quantity of gaseous fuel radially through a first air intake port of a cylinder of the engine based on at least either a load and / or an engine speed, as well as injecting a fixed quantity of liquid fuel axially into the cylinder based on at least either the load and / or the engine speed. The method can additionally include detecting a power parameter of the engine and selectively adjusting the quantity of gaseous fuel injected based on the power parameter. Brief description of the drawings

[0009] Fig. Figure 1 is a cross-sectional view of a dual-fuel engine equipped with an exemplary disclosed control system; and

[0010] Fig. 2 is an exemplary disclosed time diagram that corresponds to the control system of Fig. 1 is assigned. Detailed description

[0011] Fig. Figure 1 illustrates an example internal combustion engine 10 The engine 10 It is depicted and described as a two-stroke dual-fuel engine. The engine 10 can an engine block 12 including, at least in part, a large number of cylinders 16 defined (of which only one is shown), each with an associated cylinder head 20 exhibit. A cylinder liner 18 can occur within each engine cylinder 16 be arranged, and the cylinder head 20 can an end of the cylinder liner 18 to finish. A piston 24 can be moved within each cylinder liner 18 be arranged. A cylinder liner 18 , a cylinder head20 and a piston 24 Each of them can together form a combustion chamber 22 define the fuel from one connected to the engine 10 assembled fuel system 14 receives. It is being considered that the engine 10 any number of engine cylinders 16 with corresponding combustion chambers 22 can exhibit.

[0012] Inside the engine cylinder liner 18 can the piston 24 be designed to oscillate between bottom dead center (BDC) or lowest position and top dead center (TDC) or highest position. In particular, the piston can 24 an arrangement that includes a piston shell 26 includes a swiveling rod 28 is connected, which in turn is pivotable with a crankshaft 30 It can be connected. The crankshaft 30 of the engine 10can be rotated within the engine block 12 arranged and each piston 24 through the pole 28 with the crankshaft 30 be coupled so that a sliding movement of each piston 24 within the cylinder liner 18 in one rotation of the crankshaft 30 results. Similarly, a rotation of the crankshaft can 30 to a displacement movement of the piston 24 lead. Does the crankshaft rotate? 30 Above approximately 180 degrees, the piston shell can 26 and the associated piston rod 28 move through a complete stroke between bottom dead center (BDC) and top dead center (TDC). Since the engine 10 Since it is a two-stroke engine, it can have one complete stroke, which includes a power / exhaust / intake stroke (TDC to BDC) and an intake / compression stroke (BDC to TDC).

[0013] During a final phase of the power / exhaust / intake stroke described above, air can be drawn in through one or more gas exchange ports (e.g., air inlet ports). 32 , which are located within a side wall of the cylinder liner 18 are arranged in the combustion chamber 22 be sucked in. Especially when the piston 24 within the cylinder liner 18 As it moves downwards, a position is eventually reached in which the air intake connections 32 no longer through the piston 24 be blocked and instead come into fluid contact with the combustion chamber 22 If the air intake connections are... 32 in fluid communication with the combustion chamber 22 Standing and an air pressure at the air inlet connections 32 is greater than the pressure inside the combustion chamber 22 , air is drawn in through the air intake connections 32into the combustion chamber 22 flow. It is considered that gaseous fuel (e.g., methane or natural gas) may flow through at least one of the air intake ports. 32 into the combustion chamber 22 The gaseous fuel can be introduced (e.g., radially injected). It can mix with the air to form a fuel / air mixture within the combustion chamber. 22 to form.

[0014] Finally, the piston begins 24 an upward movement that affects the air intake connections 32 blocked and the air / fuel mixture is compressed. While the air / fuel mixture is inside the combustion chamber 22 As the mixture is compressed, its temperature can increase. At a point where the piston... 24 If the engine is located near top dead center (TDC), a liquid fuel (e.g., diesel or another petroleum-based liquid fuel) can enter the combustion chamber. 22via an injector 36 Liquid fuel is injected. The liquid fuel can be ignited by the hot air / fuel mixture, causing the combustion of both fuel types and resulting in the release of chemical energy in the form of temperature and pressure spikes within the combustion chamber. 22 This leads to the following: During the first phase of the power / exhaust / intake stroke, the pressure peak within the combustion chamber can occur. 22 the piston 24 downward pressure, thereby transferring mechanical power to the crankshaft 30 is exerted. At a specific point during this downward movement, one or more gas exchange ports (e.g., drain ports) may be present. 34 , which are inside the cylinder head 20 are arranged to open, in order to release pressurized exhaust gas within the combustion chamber 22 to let it exit, and then the beat starts again.

[0015] The injector nozzle for liquid fuel 36 can be located within the cylinder head 20 be arranged and designed to supply liquid fuel to an upper part of the combustion chamber 22 to inject the fuel axially into an interior of the cylinder liner 18 The fuel is released in a generally conical shape. The liquid fuel injector. 36 It can be configured to inject a defined quantity of liquid fuel cyclically, for example, depending on the current engine speed and / or load. In one embodiment, the engine can 10 It must be configured to run on liquid fuel injection alone or with a small amount of liquid fuel mixed with the gaseous fuel. The gaseous fuel can enter through the air intake port. 32 into the combustion chamber 22via any number of injectors 38 The fuel can be injected in gaseous form. The gaseous fuel can be introduced through a suitable air intake connection. 32 radially into the combustion chamber 22 be injected after the air intake connection 32 through the movement of the piston 24 was opened. The amount of gaseous fuel that entered the combustion chamber 22 The amount injected can vary based on engine load and / or speed, as well as on a monitored performance parameter, as described in more detail below.

[0016] The engine 10 , which the fuel system 14 If used, it can consume two types of fuel when operating as a dual-fuel engine. It is considered that the gaseous fuel accounts for between 40% and 85% of the engine's total energy output. 10can generate. For example, gaseous fuel can generate between 60% and 65% of the total energy output, with liquid fuel generating the remaining 35% to 40%. In any case, liquid fuel can act as an ignition source, so a smaller quantity is needed than for the engine. 10 This would be necessary if it only ran on liquid fuel.

[0017] As in Fig. 1 shows the fuel system 14 These include various supply components. The supply components can be an individual fuel supply line. 52 for each gaseous fuel injector 38 include a supply collection line. 51 , a common flow regulator 57 , and a fuel supply 62 may be included to deliver the gaseous fuel to the individual fuel supply line(s) 52 to supply62 can represent a fuel tank or other container designed to serve as a fuel reservoir. The fuel supply 62 can gaseous fuel at the common regulator 57 via a common fuel supply line 59 deliver. The common flow regulator 57 can be controlled to adjust an upstream parameter (e.g., pressure, flow rate, injection timing control, etc.) of the gaseous fuel and to introduce the gaseous fuel into the fuel supply manifold. 51 to direct. The supply collection line 51 can be connected to any individual fuel supply line 52 be connected to supply fuel to each gaseous fuel injector 38 to deliver. The supply line 52 and the injector for gaseous fuel 38 Both can be inside the airbox 40be arranged.

[0018] The injector nozzle for gaseous fuel 38 can be attached directly to a wall 42 of the engine block 12 inside the air box 40 or on the cylinder liner 18 be mounted so that a nozzle head 54 the injector for gaseous fuel 38 in direct connection with one of the air intake connections 32 of an adjacent engine cylinder 16 The nozzle head is standing. 54 Can a tapered nozzle head have a tapered section? 56 and a peak 58 be those with a distal end of the tapered section 56 is connected. The top 58 can create an axial flow path for gaseous fuel that leads to the central axis of the cylinder 16 is directed towards. The tapering section 56can increase the upstream pressure of the gaseous fuel passing through the downstream peak 58 into the cylinder 16 to be injected. The tapered section 56 can include an angle of approximately 60° relative to a central axis, although other angles in the range of approximately 50 to 70° are also possible.

[0019] The pressure ratio of gaseous fuel upstream and downstream, passing through the nozzle head 54 The generated flow may need to be controlled to achieve a critical or stabilized flow. For the purposes of this disclosure, a stabilized flow can be defined as the flow through the nozzle head. 54This can be defined as a flow that remains essentially unaffected by fluctuations in downstream pressure, as long as the upstream pressure remains constant. A stabilized flow can help ensure optimal fuel penetration up to approximately the middle of the combustion chamber. 22 To achieve this, in an embodiment where the gaseous fuel is methane, a minimum upstream-to-downstream pressure ratio of approximately 1.84 may be required to achieve a stabilized flow. Regardless of the type of gaseous fuel, the use of a stabilized flow can determine the fuel's downstream pressure, thus controlling the airflow through the surrounding air intake ports. 32 is overcome and the gaseous fuel reaches the center of the combustion chamber 22penetrates. To aid this penetration of the gaseous fuel, it is considered that the downstream pressure of the injected gaseous fuel can be approximately 0.5 to 4 bar higher than the pressure of the air entering the combustion chamber. 22 is initiated. This pressure difference may be necessary to allow the gaseous fuel to enter the system during the brief window of time in which the air intake ports are open. 32 are opened to access the air box 40 with the combustion chamber 22 to put into fluid contact, into the cylinder 16 to enter.

[0020] The common flow regulator 57 may be able to control the pressure of the gaseous fuel entering the gaseous fuel injector. 38 enters, to adjust in order to achieve the desired downstream pressure and stabilized flow through the nozzle head. 54 to reach the engine10 may include a control system to regulate the injection of gaseous fuel via settings through the common flow controller. 57 to regulate. The control system can use a sensor. 53 and a control unit 55 include. Based on the sensor 53 The control unit can process the generated signals 55 the fuel flow via the common flow regulator 57 adjust to maintain the desired performance. The sensor 53 can be located at any suitable point inside or near the engine 10 to be installed to measure a performance parameter in connection with the operation of the engine. 10 to monitor. The sensor 53 can be connected to the control unit 55 must be connected to provide information (by generating electronic signals) that gives details about the parameter to the control unit 55 does. The control unit 55can interpret these signals and control the fuel flow via the common flow regulator 57 Adjust accordingly.

[0021] The sensor 53 can represent a power sensor that is connected to one or more air intake ports. 32 for measuring the air and / or fuel flow through the respective air intake connections 32 is arranged. For example, the sensor can 53 at an air intake connection 32 adjacent to the air intake connection 32 be arranged so that the nozzle head 54 the injector for gaseous fuel 38 accommodates the sensor. In this scenario, the sensor can 53 a pressure sensor designed to measure the pressure of air coming out of the air box 40 into the cylinder 16 Alternatively, the sensor can 53 at an air intake connection 32 on one side of the cylinder16 opposite the injection nozzle for gaseous fuel 38 be positioned. In this case, the sensor can 53 a fuel sensor designed to detect fuel from the injector for gaseous fuel 38 to capture the one that comes out of the cylinder 16 through the respective air intake connection 32 has leaked. In both embodiments, the sensor can 53 Information about airflow and / or fuel is sent to the control unit 55 send instructions to the common flow controller. 57 can transmit this information in order to adjust the fuel pressure and / or flow rate in response. The sensor 53 It could take different forms and / or be arranged in different locations to efficiently measure the target parameters. The possibility of using multiple sensors, if desired, is also being considered. 53can be used to monitor the same and / or different parameters.

[0022] It is also being considered that the sensor 53 It can be used to detect the presence of an exhaust gas component (e.g., nitrogen oxides (NOx), particulate matter, hydrocarbons, carbon monoxide, carbon dioxide, etc.) above a threshold level as a performance parameter. The control system can adjust the flow of gaseous fuel in response to undesired levels of the specific component detected by the sensor. 53 to adjust the monitored exhaust gas component in order to initiate a reduction in the corresponding emission.

[0023] In an alternative embodiment, the sensor can 53 represent a knock sensor that is located at a suitable point on or near the engine block 12 It may be arranged to transmit information regarding the combustion of the dual fuel to the control unit. 55to deliver. For example, the knock sensor 53 be designed to detect the frequency of a pressure wave generated by fuel combustion within the combustion chamber 22 The knock sensor is used to measure a condition of the combustion process, either by generating a specific noise or by measuring it in some other way. If this condition reaches a certain threshold, such as a measured frequency outside a target range, engine knocking (i.e., a certain degree of incomplete combustion of fuel) may be present. 53 can be used with the control unit 55 be connected and trained to the control unit 55 to provide a signal that gives information about the combustion process. If it is determined that adjustments are necessary, the control unit can 55 the common injector regulator 57 signal to set a parameter only for the injected gaseous fuel until the knock sensor detects it 53The measured condition lies within the target range.

[0024] Fig. Figure 2 illustrates a timing diagram for an example dual-fuel engine. Fig. 2 is described in detail in the following section to further illustrate the concepts revealed. Commercial applicability

[0025] The fuel system 14 It can be used in a new dual-fuel engine or retrofitted into an existing single-fuel engine. The fuel system 14 It can replace a single-fuel system, allowing the associated engine to be used in a cleaner and more cost-effective manner. A control system can be provided to ensure the efficient use of the fuel system. 14 to help ensure this. Efficient control can be achieved through the use of a sensor. 53for monitoring a critical parameter and providing feedback to the fuel system 14 through a control unit 55 This is made possible. In particular, feedback from the control system can be used to adjust the injection of gaseous fuel based on an operating condition, such as the engine load and / or speed. 10 , to adjust. This can be advantageous, as the injector is designed for liquid fuel. 36 mechanically, it can be actuated cyclically without any input from the control system. This means that the liquid fuel injector can be operated in a controlled manner. 36 can be configured to deliver the same amount of liquid fuel for each combustion cycle (i.e., for a given load condition and / or engine speed). 10 ) to inject regardless of fluctuations in environmental factors, age-related factors, etc.

[0026] Fig. Figure 2 is an example time diagram. 100 , which is related to the operation of the engine 10 and the fuel system 14 is related. The engine can start when an operator turns a key to start the engine. 10 to start. Fuel can be drawn from the fuel reservoirs (e.g., fuel supply). 62 ) to each cylinder 16 be pumped. The engine can be started. 10 conventionally only with liquid fuel injections near TDC 102 (between a liquid injection starting point 106 and a liquid injection endpoint 108 ) run, although it is also possible that the initial combustion cycles include both fuels. After starting, and during the piston 24 in its power / exhaust / intake stroke to bottom dead center (BDC) 104 When moved, the outlet connections can 34 near a point 110 be opened. The piston24 can move further downwards until the piston shell 26 begins, the air intake connections 32 at a relevant point 112 in Fig. 2 to expose. Once the piston shell 26 the bottom of the air intake connections 32 What happens can happen. 32 must be fully open. Then gaseous fuel can flow from the gaseous fuel injector. 38 during a time period between corresponding points 114 and 116 are injected while the air intake connections 32 are open. During this period, air can also escape from the air box. 40 into the cylinder 16 enter. While the piston 24 from UT 104 as the piston shell is moved upwards 26 gradually the air intake connections 32 Close. The air intake connections 32 can at one point 118be completely closed. The entire injection of gaseous fuel can occur before this point is reached. It is considered that gaseous fuel is injected for approximately 25% to 40% of the total time period between 112 and 118 , during which the air intake connections 32 are open, and the injection takes place. In one embodiment, this injection time (between 114 and 116 ) only during the second half of this time period, when the piston 24 is in its intake compression stroke. After gaseous fuel has been injected and the intake ports are closed. 32 If the outlet ports are closed, they can be located near a point. 120 close. Before reaching OT 102 Can the injection of liquid fuel at point 106 begin. The piston finishes. 24During its intake / compression stroke, the injected liquid fuel can cause the combustion of the entire fuel mixture and thus restart the cycle.

[0027] The air and fuel flows into and out of the cylinder 16 can be through the sensor 53 The system is monitored to allow for adjustments if necessary. For example, a pressure adjustment may be required if the pressure at the air inlet port is too high. 32 The injected fuel is insufficient to overcome the pressure of the air entering through the air intake ports. 32 into the cylinder 16 enters. The air pressure can be measured at an air inlet connection. 32 adjacent to the air intake connection 32 The system into which gaseous fuel is injected is monitored. This is done via the sensor. 53 Collected data can be sent to the control unit 55sent and interpreted (by comparison with data from the controller) 57 or a separate sensor in the injector for gaseous fuel 38 ), to determine whether a fuel pressure adjustment is necessary to achieve a desired pressure differential (approximately 2 to 4 bar) between the downstream fuel injection and the intake air. If a pressure adjustment is necessary, the control unit can 55 Instructions to the common flow controller 57 send to increase the fuel flow rate to the gaseous fuel injector 38 to adjust so that the injection pressure is brought into the desired range. It is also being considered that the sensor 53It can monitor other operating conditions, such as temperature, speed, timing, and the like; such data can then be translated into instructions for controlling the system to ensure a strong flow of fuel into the cylinder.

[0028] For example, the sensor can 53 are used to prevent fuel from escaping from the intake ports. 32 to detect. The sensor 53 can also be located outside of an air intake connection 32 on one side of the cylinder 16 opposite the injection nozzle for gaseous fuel 38 be arranged to capture fuel escaping from the cylinder 16 has leaked. If such fuel is detected, or if the amount of detected fuel exceeds a threshold level, the pressure of the injected gaseous fuel can be adjusted by the control unit. 55 via the common flow regulator 57be adjusted. The use of the sensor 53 The control system in this way can lead to better fuel retention within the cylinder. 16 and thus to improved efficiency of the fuel system 14 contribute.

[0029] Another option could be to use the sensor 53 to use as a knock sensor to monitor fuel combustion within the combustion chamber 22 to monitor the pressure of the gaseous fuel that passes through the gaseous fuel injector. 38 The injected fluid can be controlled by the common flow regulator. 57 be increased until the knock sensor 53 The sensor detects a pressure wave threshold frequency generated by fuel combustion, which signals engine knocking. 53 can send information to the control unit 55to direct the pressure of the injected gaseous fuel across the common flow regulator 57 to reduce until combustion occurs without knocking.

[0030] During or after a given combustion cycle, the sensor can 53 detecting a parameter outside a desired range. If this is the case, the sensor can 53 generate a signal that specifies the parameter, and send this signal to the control unit 55 send. The control unit 55 can interpret these signals and send instructions to the common flow controller 57 (or, if present, individual flow regulators within the gaseous fuel injectors) 38 ) to set a parameter (e.g. pressure, flow rate, timing, etc.) so that the flow can be optimized to cover the desired area through the sensor 53It is monitored to ensure compliance. This type of dynamic control system can be useful for monitoring the fuel system. 14 and the engine 10 to enable them to work efficiently while adapting to changes in operating conditions.

[0031] It will be clear to those skilled in the art that various modifications and variations can be made to the disclosed motor and control system. Other embodiments will become apparent to them from considering the description and a practical implementation of the control system disclosed herein. The description and examples are to be regarded as purely illustrative, with the true scope being indicated by the following claims and their equivalent embodiments.

Claims

[1] Control system for a dual-fuel engine ( 10 ), comprehensive: an injector ( 38 ) for gaseous fuel, which has a nozzle head ( 54 ) which is located at the first air intake connection ( 32 ) of a cylinder ( 16 ) of the engine and is designed to inject a variable amount of gaseous fuel radially into the cylinder based on at least either a load and / or an engine speed; an injector ( 36 ) for liquid fuel, designed to inject a fixed quantity of liquid fuel axially into the cylinder based on at least either the load and / or speed of the engine; a controller ( 57 ), which is designed to selectively adjust the flow of gaseous fuel to the gaseous fuel injector; at least one sensor ( 53), which is designed to generate a signal that indicates a performance parameter of the motor; and a control unit ( 55 ), which is connected to the controller and at least one sensor, wherein the control unit is designed to selectively cause the controller to adjust the flow of gaseous fuel on the basis of the signal. [2] Control system according to claim 1, wherein the sensor is connected to a second air inlet port ( 32 ) of the cylinder. [3] Control system according to claim 2, wherein the performance parameter is a pressure of the air entering the cylinder through the second air inlet port. [4] Control system according to claim 2, wherein the performance parameter is the presence of gaseous fuel that has escaped from the cylinder through the second air inlet port. [5] Control system according to claim 1, wherein the performance parameter is the presence of an exhaust gas component above a certain threshold level. [6] Control system according to claim 1, wherein the performance parameter is a frequency of a pressure wave generated by fuel combustion. [7] Method for controlling the operation of a dual-fuel engine ( 10 ), the procedure comprising the following steps: Injection of a variable quantity of gaseous fuel radially through a first air intake port ( 32 ) of a cylinder ( 16 ) of the engine based on at least either a load and / or an engine speed; Injecting a fixed amount of liquid fuel axially into the cylinder based on at least either the load and / or the speed of the engine; Recording a performance parameter of the engine; and Selective adjustment of the amount of gaseous fuel injected based on the performance parameter. [8] Method according to claim 7, wherein adjusting the gaseous fuel injection comprises adjusting the pressure of the gaseous fuel injected into the cylinder to a pressure that is about 0.5 to 4 bar higher than the pressure of the air entering the cylinder. [9] Method according to claim 7, wherein the injection of the gaseous fuel comprises injecting the gaseous fuel for about 25 to 40% of a time period during which the first air inlet port is open. [10] Method according to claim 7, wherein the injection of the variable quantity of gaseous fuel involves guiding gaseous fuel through a tapered nozzle head ( 54 ) includes, which is designed to stabilize the flow of gaseous fuel.