gas engine

Abstract

To provide a gas engine which is suppressed in influence of a backfire on combustion cycles subsequent to a combustion cycle in which the backfire has occurred, and influence of a cylinder in which the backfire has occurred on other cylinders.SOLUTION: In a gas engine 2 of the present invention, a controller 14 detects a cylinder unit 32 in which a backfire caused by pressure from a sensor 28 has occurred, determines a cylinder unit to be stopped among cylinder units 32 other than the cylinder unit 32 in which the backfire has occurred, and stops fuel injection from a fuel injector 18 to the cylinder unit in which the backfire has occurred for a predetermined time period after detection of the backfire, and when there is any cylinder to be stopped, also stops fuel injection from the fuel injector 18 to that cylinder.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a gas engine.

Background Art

[0002] A gas engine usually has a plurality of cylinders. These cylinders are connected to a common manifold via intake ports, and air is sent from the manifold to each intake port. Generally, gas fuel is supplied through a fuel injector at the intake port or in the cylinder. The fuel mixed with air is ignited in the cylinder.

[0003] When the fuel mixture gas moves from the intake port to the cylinder, ignition may occur due to reasons such as the fuel touching the high-temperature part of the cylinder, and "backfire" may occur where this combustion spreads from the cylinder into the intake port. In particular, in an engine using hydrogen as fuel, which has a wider explosion limit concentration range and lower ignition energy compared to natural gas, backfire is likely to occur. Backfire can hinder safe and stable combustion. Studies on the detection and treatment of backfire have been reported in JP-A-2016-130473, JP-A-2006-57596, and JP-A-2006-527113.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The effects of a flashback can extend not only to the combustion cycle in which it occurred, but also to subsequent combustion cycles. There is a high probability of a "sequence of flashbacks" occurring, where a flashback causes irregular combustion in combustion cycles following the one in which it occurred. Furthermore, since the intake port in which a flashback occurs is connected to other intake ports via the manifold, the effects of the flashback can also affect combustion in other cylinders. A flashback can potentially be a cause of irregular combustion in other cylinders. A gas engine is desired that suppresses the chain reaction of flashbacks and the cause of irregular combustion in other cylinder units by flashbacks.

[0006] The inventor's intention is to provide a gas engine in which the chain reaction of flashbacks and the resulting cause of irregular combustion in other cylinder units are suppressed. [Means for solving the problem]

[0007] The gas engine comprises a plurality of cylinder units, a manifold that supplies air to the plurality of cylinder units, and a controller. Each of the plurality of cylinder units comprises a cylinder, an intake port connected to the cylinder, an intake valve located between the cylinder and the intake port, a sensor that measures the pressure inside the cylinder, and a fuel injector that injects fuel. The controller detects the cylinder unit where a flashback is occurring based on the pressure from the sensor, determines which cylinder units other than the cylinder unit where the flashback is occurring are to be stopped, and stops fuel injection from the fuel injector to the cylinder unit where the flashback is occurring for a predetermined period after the detection of the flashback, and stops fuel injection from the fuel injector to the stopped cylinder unit if there are any stopped cylinder units. [Effects of the Invention]

[0008] In this gas engine, the controller determines which cylinder units to shut down, excluding the cylinder unit where flashback is occurring, and stops fuel injection to the cylinder unit where flashback is occurring and to the shut-down cylinder unit. This prevents flashback from causing irregular combustion in other cylinder units. Furthermore, the controller maintains this fuel injection shutdown for a predetermined period of time. This prevents a chain reaction of flashbacks. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing a gas engine according to one embodiment. [Figure 2] Figure 2 is a schematic diagram showing a cross-section along the line II-II in Figure 1. [Figure 3] Figure 3 shows the processing flow of the controller in Figure 1. [Figure 4] Figure 4A is a graph showing the detection of flashback, and Figure 4B is a graph showing the detection of high-pressure and low-pressure misfires. [Figure 5] Figure 5 is a graph showing how low heat is detected. [Figure 6] Figures 6A and 6B are schematic diagrams showing an example of a stopped cylinder unit in the gas engine of Figure 1. [Figure 7] Figures 7A and 7B are schematic diagrams showing examples of stopped cylinder units in a gas engine of another embodiment. [Figure 8] Figures 8A and 8B are schematic diagrams illustrating examples of stopped cylinder units in gas engines of yet other embodiments. [Modes for carrying out the invention]

[0010] Preferred embodiments will be described in detail below, with reference to drawings as appropriate.

[0011] Figure 1 is a schematic diagram showing a gas engine 2. This gas engine 2 burns a mixture of gaseous fuel and air. In this embodiment, the gaseous fuel is hydrogen. The gaseous fuel may be natural gas or other combustible gases. This gas engine 2 may be used in devices that are mainly operated at a steady rate, such as generators, or in devices where the load changes frequently, such as propellers for ships. As shown in Figure 1, this gas engine 2 includes a compressor 4, an intake passage 6, a manifold 8, a cylinder 10, an exhaust passage 12, and a controller 14.

[0012] The compressor 4 takes in air, compresses it, and sends it to the intake passage 6. The intake passage 6 is connected to the manifold 8. Air from the compressor 4 is sent to the manifold 8 through the intake passage 6. As shown in Figure 1, in this embodiment, the intake passage 6 is connected to the center of the manifold 8.

[0013] Multiple cylinders 10 are arranged along a manifold 8. In this embodiment, the cylinders 10 are arranged in two rows. Each cylinder 10 in one row faces a corresponding cylinder 10 in the other row. This gas engine 2 is a V-type 12-cylinder engine. Air from the compressor 4 is supplied to each cylinder 10 via the manifold 8.

[0014] Figure 2 is a schematic diagram showing a portion of the cross-section along line II-II in Figure 1. As shown in Figures 1 and 2, the gas engine 2 further comprises an intake port 16, fuel injector 18, intake valve 20, igniter 22, exhaust port 24, exhaust valve 26, pressure sensor 28, and piston 30, each corresponding to a cylinder 10. In this specification, a set of cylinders 10, intake port 16, fuel injector 18, intake valve 20, igniter 22, exhaust port 24, exhaust valve 26, pressure sensor 28, and piston 30 is collectively referred to as a "cylinder unit 32". That is, the gas engine 2 comprises 12 cylinder units 32. In the gas engine 2, two rows of six cylinder units 32 are arranged along the manifold 8.

[0015] In the cylinder unit 32, when the side of the manifold 8 is taken as the inner side and the opposite side of the manifold 8 is taken as the outer side, in FIG. 2, the intake port 16, the igniter 22, and the exhaust port 24 are arranged in this order from the inner side to the outer side. The intake port 16, the igniter 22, and the exhaust port 24 may be arranged in a direction parallel to the direction in which the manifold 8 extends in this order. That is, the cylinder unit 32 may be connected to the manifold 8 in a state rotated 90° with respect to FIG. 2. Also, the manifold 8 may be in one row or two rows.

[0016] The intake port 16 connects the manifold 8 and the cylinder 10. The fuel injector 18 injects gaseous fuel into the intake port 16. The fuel injector 18 may inject gaseous fuel into the cylinder 10. The air from the manifold 8 is mixed with the gaseous fuel and sent into the cylinder 10 as an air-fuel mixture. The igniter 22 ignites the air-fuel mixture in the cylinder 10. The igniter 22 is typically a spark plug. Depending on the fuel, the igniter 22 may be a pilot injection valve. The air-fuel mixture burns, and thereby the piston 30 moves up and down. The lower end of the piston 30 is connected to a crankshaft (not shown). The up-and-down movement of the piston 30 is converted into the rotational movement of the crankshaft. The gas after combustion is discharged from the exhaust port 24. Although omitted in FIG. 1, each exhaust port 24 is connected to the exhaust passage 12. The exhaust from each cylinder 10 is returned to the compressor 4 through the exhaust passage 12. The pressure sensor 28 continuously measures the internal pressure of the cylinder 10.

[0017] This gas engine 2 is a four-stroke engine. That is, in each cylinder unit 32, an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke are repeated. The set of the intake stroke, the compression stroke, the combustion stroke, and the exhaust stroke constitutes a combustion cycle. In one combustion cycle, the crankshaft rotates twice. Here, in each cylinder unit 32, the position of the piston 30 is represented by a crank angle based on the crank angle at top dead center. When the piston 30 is at top dead center in the combustion stroke, the crank angle is set to 0°. For example, when the piston 30 is at top dead center in the intake stroke, the crank angle is 360°.

[0018] As shown by the arrow P in FIG. 1, a pressure sensor 28 of each cylinder unit 32 is connected to the controller 14. The internal pressure of the cylinder 10 measured by each pressure sensor 28 is continuously input to the controller 14. As shown by the arrow C in FIG. 1, a fuel injector 18 of each cylinder unit 32 is connected to the controller 14. The controller 14 can control the injection and stop of fuel for each fuel injector 18. Further, the output from the crank angle sensor is input to the controller 14, and the controller 14 uses this to calculate the crank angle (e.g., -360° to +360°) based on an arbitrary process of each cylinder unit 32. The controller 14 uses these functions to perform the processes of detecting and suppressing backfire for each cylinder unit 32. In this embodiment, the controller 14 is composed of a processor and a program that operates this processor. Part or all of the controller 14 may be composed of a dedicated circuit.

[0019] FIG. 3 shows the processing flow of the controller 14. As shown in FIG. 3, the processing of the controller 14 includes steps from S1 to S6.

[0020] In step S1, the controller 14 obtains the internal pressure of the cylinder 10 and the corresponding crank angle from each cylinder unit 32. For each cylinder unit 32, the change in internal pressure corresponding to the change in crank angle is obtained.

[0021] In step S2, the controller 14 determines whether or not a flashback has occurred and whether or not there are signs of a flashback. Specifically, the controller 14 performs "flashback detection," "high-pressure misfire detection," "low-pressure misfire detection," and "weak flame detection" for each cylinder unit 32.

[0022] In "backfire detection," the controller 14 directly detects backfire. Figure 4A shows the method of backfire detection. In Figure 4A, the horizontal axis represents the crank angle, and the vertical axis represents the internal pressure of the cylinder 10. The symbol IVO represents the crank angle when the intake valve 20 is open, and the symbol IVC represents the crank angle when the intake valve 20 is closed. Backfire is a phenomenon in which fuel ignites during the intake stroke, and this combustion spreads into the intake port 16. Normally, during the intake stroke, the internal pressure of the cylinder 10 is approximately the intake pressure, but when backfire occurs, the internal pressure of the cylinder 10 increases during the intake stroke. The solid line Lb in Figure 4A is an example of the change in internal pressure when backfire occurs.

[0023] The controller 14 detects whether the internal pressure P of the cylinder 10 may exceed a predetermined threshold Tb during the period when the intake valve 20 is open. When it is detected that the internal pressure P may exceed the threshold Tb, the controller 14 determines that a flashback has occurred. In the example in Figure 4A, a flashback is detected in section I. The threshold Tb is determined from the intake pressure estimated from the internal pressure of the cylinder 10 or from the internal pressure of the manifold 8.

[0024] In "low-pressure misfire detection," the controller 14 detects "low-pressure misfires" that may occur when a flashback occurs. Figure 4B shows the method for detecting low-pressure misfires. In Figure 4B, the horizontal axis represents the crank angle, and the vertical axis represents the internal pressure of the cylinder 10. The symbol TDC represents the top dead center in the combustion stroke, and the symbol Bx represents the crank angle at ignition. The dashed line A represents the change in average internal pressure Pa. The average internal pressure Pa is the average value of the internal pressure over the most recent predetermined number of combustion cycles at each crank angle. The average internal pressure Pa is calculated in step 6, which will be described later. When a flashback occurs, the burnt gas is drawn into the cylinder 10, causing the internal pressure to become lower than normal during the compression stroke and sometimes resulting in a misfire. This is a "low-pressure misfire." The solid line Ll in Figure 4B is an example of the change in internal pressure when a low-pressure misfire occurs. The misfire condition is determined by checking whether the difference between the internal pressure of cylinder 10 at a crank angle of -θ° and the internal pressure of cylinder 10 at a crank angle of θ°, as shown in Figure 5 below, is within a predetermined range.

[0025] The controller 14 determines whether the difference (P-Pa) between the internal pressure P and the average internal pressure Pa of the cylinder 10 at a predetermined crank angle α during the compression stroke is less than or equal to a predetermined threshold TL (a negative value). When the difference (P-Pa) is less than or equal to the threshold TL and indicates a misfire state, the controller 14 determines that it has detected the occurrence of a low-pressure misfire. In the example of the solid line Ll in Figure 4B, the occurrence of a low-pressure misfire has been detected.

[0026] In "high-pressure misfire detection," the controller 14 detects a "high-pressure misfire" that may occur when a flashback occurs. Figure 4B shows the method for detecting a high-pressure misfire. When a flashback occurs, the cylinder 10 becomes hot, autoignition occurs during the compression stroke, the internal pressure becomes higher than normal, and a misfire state may occur. This is a "high-pressure misfire." The straight line Lh in Figure 4B is an example of the change in the internal pressure of the cylinder 10 when a high-pressure misfire occurs.

[0027] The controller 14 determines whether the difference (P-Pa) between the internal pressure P and the average internal pressure Pa of the cylinder 10 at a predetermined crank angle β during the compression stroke is greater than or equal to a predetermined threshold Th. If the difference (P-Pa) is greater than or equal to the threshold Th and indicates a misfire state, the controller 14 determines that it has detected the occurrence of a high-pressure misfire. In the example of the solid line Lh in Figure 4B, the occurrence of a high-pressure misfire has been detected. Note that in the example of Figure 4B, the crank angles α and β are the same. The crank angles α and β may be different.

[0028] In "low flame detection," the controller 14 detects "low flame," a phenomenon that foreshadows flashback. Figure 5 shows the method of low flame detection. Low flame is a phenomenon in which the internal pressure of cylinder 10 is normal during the compression stroke, but during the combustion stroke after ignition, the internal pressure of cylinder 10 is lower than in the case of normal combustion and higher than in the case of a complete misfire. When a low flame occurs, fuel remains unburned and the cylinder 10 becomes hot during the exhaust stroke, making it easier for a flashback to occur during the intake stroke of the next combustion cycle. The solid line Lw in Figure 5 is an example of the change in internal pressure of cylinder 10 when a low flame occurs. The dashed line A represents the change in the average internal pressure Pa. The dashed line labeled "at misfire" represents the typical change in internal pressure when a misfire occurs.

[0029] In Figure 5, the symbol P(-θ) represents the pressure in cylinder 10 during the compression stroke when the crank angle is angle θ before top dead center. The symbol P(θ) represents the pressure in cylinder 10 when the crank angle is angle θ after top dead center. The controller 14 determines whether the difference ΔP(P(θ)-P(-θ)) is greater than or equal to a predetermined first threshold T1 and less than or equal to a predetermined second threshold T2. When the difference ΔP(P(θ)-P(-θ)) is greater than or equal to the first threshold T1 and less than or equal to the second threshold T2, it is determined that the occurrence of a weak flame has been detected. In the example of the solid line Lw in Figure 5, the occurrence of a weak flame has been detected.

[0030] If flashback, high-pressure misfire, or low-pressure misfire is detected in step S2, step S3 is executed. If a weak flame is detected in step S2, step S5 is executed. If no flashback, high-pressure misfire, low-pressure misfire, or weak flame is detected in step S2, step S6 is executed.

[0031] In step S3, the controller 14 targets cylinder units 32 other than the cylinder unit 32 in which flashback, high-pressure misfire, or low-pressure misfire has been detected (referred to as the flashback detection unit) and determines which cylinder units 32 are likely to be affected by flashback and will be stopped (referred to as the stopped cylinder units). In this embodiment, the controller 14 designates the following cylinder units 32 as the stopped cylinder units. (i) Cylinder unit 32 (referred to as the opposing unit) facing the flashback detection unit (ii) The flashback detection unit and the cylinder unit 32 adjacent to the downstream side of the airflow in the manifold 8 (referred to as the downstream adjacent unit) (iii) The opposing unit and the cylinder unit 32 adjacent to the downstream side of the airflow in the manifold 8 (referred to as the opposing-downstream adjacent unit)

[0032] Figure 6A shows an example of a stopped cylinder unit. In Figure 6A, only the manifold 8 and cylinder units 32 are shown in a simplified manner. In Figure 6A, the symbol Io represents the air inlet from the intake passage 6. The arrows represent the airflow within the manifold 8. In Figure 6A, the cylinder unit 32 with a hatch is the flashback detection unit. The cylinder unit 32 represented by a double frame is the stopped cylinder unit. In the example in Figure 6A, a total of three cylinder units 32 are considered to be the stopped cylinder unit: (i) the opposing unit, (ii) the downstream adjacent unit, and (iii) the opposing-downstream adjacent unit.

[0033] Figure 6B shows another example of a stop cylinder unit. In this figure, the flashback detection unit is located furthest downstream in the airflow in manifold 8. Therefore, there are no downstream adjacent units or opposing-downstream adjacent units. In this case, (i) only the opposing unit is considered a stop cylinder unit.

[0034] In step S4, the controller 14 stops fuel injection to the flashback detection unit and the cylinder stop unit. In this embodiment, fuel injection in the flashback detection unit and the cylinder stop unit is stopped for a total of two combustion cycles: the combustion cycle in which the flashback is detected and the next combustion cycle. Fuel injection is resumed in the subsequent combustion cycle. Fuel injection in the flashback detection unit and the cylinder stop unit may be stopped for three combustion cycles, or for four or more combustion cycles. Fuel injection in the flashback detection unit and the cylinder stop unit may be stopped only in the combustion cycle in which the flashback is detected. When step S4 is completed, the process returns to step S1.

[0035] In step S5, the controller 14 stops fuel injection in the cylinder unit 32 where a weak flame has been detected for the next combustion cycle. Fuel injection is resumed in the subsequent combustion cycle. Fuel injection in the unit 32 where a weak flame has been detected may be stopped for several subsequent combustion cycles. When step S5 is completed, the process returns to step S1.

[0036] In step S6, the controller 14 uses the internal pressure of cylinder 10 obtained in step S1 to calculate the average internal pressure at this crank angle over a predetermined number of recent combustion cycles. For example, the average internal pressure at this crank angle over the last 10 combustion cycles is calculated. The calculation result is stored and later used for the determination in step S2.

[0037] In this embodiment, the processing of the controller 14 shown in Figure 3 starts when the gas engine 2 is started and ends with an interrupt process such as stopping the gas engine 2.

[0038] The effects and advantages of this embodiment will be explained below.

[0039] In this gas engine 2, the controller 14 determines which cylinder units to stop, targeting cylinder units 32 other than the flashback detection unit. The controller 14 stops fuel injection not only to the flashback detection unit but also to the stopped cylinder units. This suppresses the possibility of flashback causing irregular combustion in other cylinder units 32.

[0040] In this embodiment, fuel injection is stopped for two combustion cycles in the flashback detection unit and the cylinder stop unit. The effects of flashback may persist beyond one combustion cycle. By stopping fuel injection for multiple combustion cycles, irregular combustion in the flashback detection unit and cylinder stop unit is effectively suppressed in combustion cycles following the one in which flashback occurred. In this embodiment, the "flashback chain reaction," in which flashback causes irregular combustion in subsequent combustion cycles, is suppressed.

[0041] In this embodiment, the opposing unit is a stopped cylinder unit. The effects of flashback are likely to extend to the cylinder unit 32 opposite to the cylinder unit 32 where the flashback occurred. By making the opposing unit a stopped cylinder unit, irregular combustion in this cylinder unit 32 is suppressed.

[0042] In this embodiment, the downstream adjacent unit is designated as a stop cylinder unit. The cylinder unit 32 adjacent to the downstream airflow of the flashback detection unit is susceptible to flashback. By designating the downstream adjacent unit as a stop cylinder unit, irregular combustion in this cylinder unit 32 is suppressed.

[0043] In this embodiment, the opposing-downstream adjacent unit is designated as a stop cylinder unit. The opposing-downstream adjacent unit is adjacent to the opposing unit downstream and faces the downstream adjacent unit. The opposing-downstream adjacent unit is also susceptible to flashback. By designating this cylinder unit 32 as a stop cylinder unit, irregular combustion in this cylinder unit 32 is suppressed.

[0044] The opposing unit may be designated as the stopped cylinder unit, or the downstream adjacent unit may be designated as the stopped cylinder unit. The opposing unit and the downstream adjacent unit may be designated as the stopped cylinder units. By reducing the number of cylinder units 32 that stop fuel injection, the decrease in output of the gas engine 2 can be suppressed.

[0045] In this embodiment, fuel injection is not stopped in cylinder units 32 other than the flashback detection unit and the cylinder stop unit. By stopping fuel injection only in the flashback detection unit and the cylinder units 32 that are susceptible to the effects of this flashback, the occurrence of irregular combustion is suppressed while preventing a decrease in the output of the gas engine 2.

[0046] In this embodiment, the control device detects the occurrence of flashback not only by directly detecting the flashback phenomenon, but also by detecting low-pressure misfires and high-pressure misfires. This effectively suppresses the possibility of missing the occurrence of flashback.

[0047] In this embodiment, the control device detects a weak flame that is a precursor to flashback and stops fuel injection in the cylinder unit 32 where the weak flame is detected. A weak flame is unlikely to cause misfires in other cylinder units 32. There is little need to stop fuel injection in cylinder units 32 other than the one where the weak flame occurred. Also, with a weak flame, there is little need to stop fuel injection over multiple combustion cycles. By detecting a weak flame and preventing flashback, the number of cylinder units 32 and combustion cycles for which fuel injection is stopped can be reduced compared to when a flashback occurs. This gas engine 2 has a reduced power output.

[0048] Figures 7A and 7B are schematic diagrams showing gas engines 40 and 46 according to other embodiments. In Figures 7A and 7B, only the manifolds 42 and 48 and cylinder units 44 and 50 are shown in a simplified manner. In these gas engines 40 and 46, the cylinder units 44 and 50 are arranged in two rows along the manifolds 42 and 48. These gas engines 40 and 46 are V-type 18-cylinder engines. In Figures 7A and 7B, the symbol Io represents the air inlet from the intake passage. The arrows represent the airflow within the manifolds 42 and 48. In Figures 7A and 7B, the cylinder units 44 and 50 with hatches are flashback detection units.

[0049] In the embodiment shown in Figure 7A, the air inlet Io from the intake passage is located in the center of the manifold 42. In this example, when the x-coordinate is the coordinate in the direction in which the manifold 42 extends, the area occupied by the inlet Io and the area occupied by the intake port of the flashback detection unit overlap in the x-coordinate. In Figure 7A, the cylinder units 44 adjacent to both sides of the flashback detection unit are all located downstream of the flashback detection unit in the airflow. The cylinder units 44 adjacent to both sides of the flashback detection unit are all downstream adjacent units. In this example, a total of five cylinder units 44 are designated as stop cylinder units: (i) the opposing unit, (ii) the two downstream adjacent units, and (iii) the two opposing-downstream adjacent units. In Figure 7A, the cylinder units 44 represented by the double frame are stop cylinder units.

[0050] In the embodiment shown in Figure 7B, the air inlet Io from the intake passage is provided at the end of the manifold 48. The air from the inlet Io flows from one end of the manifold 48 to the other end. As shown in Figure 7B, in this example, a total of three cylinder units 50 are designated as stop cylinder units: (i) opposing unit, (ii) downstream adjacent unit, and (iii) opposing-downstream adjacent unit. In Figure 7B, the cylinder units 50 represented by double frames are stop cylinder units.

[0051] Figures 8A and 8B are schematic diagrams showing gas engines 52 and 58 according to yet another embodiment. In these gas engines 52 and 58, the cylinder units 56 and 62 are arranged in a row of nine columns along the manifolds 54 and 60. These gas engines 52 and 58 are in-line nine-cylinder engines. In these gas engines 52 and 58, there are no cylinder units facing each other. In Figures 8A and 8B, the symbol Io represents the air inlet from the intake passage. The arrows represent the airflow within the manifolds 54 and 60. In Figures 8A and 8B, the cylinder units 56 and 62 with hatches are flashback detection units.

[0052] In the embodiment shown in Figure 8A, the air inlet Io from the intake passage is located in the center of the manifold 54. As shown in Figure 8A, in this example, (ii) two downstream adjacent units are designated as stop cylinder units. In Figure 8A, the cylinder unit 56, represented by a double frame, is a stop cylinder unit.

[0053] In the embodiment shown in Figure 8B, the inlet Io is located at the end of the manifold 60. Air from the inlet Io flows from one end of the manifold 60 to the other. As shown in Figure 8B, in this example, the flashback detection unit is located furthest downstream in the airflow. Therefore, there are no downstream adjacent units. In this embodiment, there is no cylinder stop unit. In this embodiment, fuel injection is stopped only for the flashback detection unit.

[0054] In the embodiments described above, the control device performed flashback detection and detection of a weak flame that was a precursor to flashback. The control device may perform only flashback detection and not weak flame detection. The control device may perform only weak flame detection and not flashback detection.

[0055] As explained above, in a gas engine, the occurrence of irregular combustion due to flashback in cylinders other than the one where flashback occurred is suppressed. From this, the superiority of this gas engine is clear.

[0056] The functions of the controllers disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits or means, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit or means is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0057] [Disclosure items] The following items constitute a disclosure of preferred embodiments.

[0058] [Item 1] It comprises multiple cylinder units, a manifold that supplies air to the multiple cylinder units, and a controller. Each of the plurality of cylinder units comprises a cylinder, an intake port connected to the cylinder, an intake valve located between the cylinder and the intake port, a sensor for measuring the pressure inside the cylinder, and a fuel injector for injecting fuel. The controller detects the cylinder unit in which flashback is occurring based on the pressure from the sensor, Determination of a cylinder unit to be stopped, targeting cylinder units other than the cylinder unit in which the aforementioned flashback occurred, A gas engine that, after detecting the flashback, stops fuel injection from the fuel injector to the cylinder unit where the flashback is occurring, and also stops fuel injection from the fuel injector to any stopped cylinder unit if such a cylinder unit exists, for a predetermined period of time.

[0059] [Item 2] The plurality of cylinder units are arranged in one or two rows along the manifold, The gas engine according to item 1, wherein the controller is located downstream of the cylinder unit in the manifold from the cylinder unit in which the flashback was detected, and the cylinder unit adjacent to the cylinder unit in which the flashback was detected is designated as the stopped cylinder unit.

[0060] [Item 3] The gas engine according to item 1 or 2, wherein the plurality of cylinder units are arranged in two rows along the manifold, with each cylinder unit in one row facing a corresponding cylinder unit in the other row, and the controller designates the cylinder unit facing the cylinder unit where the flashback was detected, or the cylinder unit adjacent to the cylinder unit facing the cylinder unit where the flashback was detected on the downstream side of the airflow in the manifold, as the stopped cylinder unit.

[0061] [Item 4] A gas engine according to any one of items 1 to 3, wherein the controller detects flashback by detecting that the pressure in the cylinder exceeds a predetermined threshold during the opening period of the intake valve, or by detecting that the pressure in the cylinder falls outside a predetermined range during the compression stroke.

[0062] [Item 5] The controller further performs the following: detection of a cylinder unit where a weak flame is occurring based on the pressure detected by the sensor, and stopping fuel injection from the fuel injector to the cylinder unit where the weak flame is occurring for a predetermined period of time after the detection of the weak flame. A gas engine according to any one of items 1 to 4, wherein the controller detects the occurrence of a weak flame by detecting that the difference ΔP = P(θ) - P(-θ) is greater than or equal to a first threshold T1 and less than or equal to a second threshold T2, when P(-θ) is the pressure in the cylinder during the compression stroke when the crank angle is a predetermined angle θ before top dead center, and P(θ) is the pressure in the cylinder during the combustion stroke when the crank angle is a predetermined angle θ after top dead center.

[0063] [Item 6] It comprises multiple cylinder units, a manifold that supplies air to the multiple cylinder units, and a controller. Each of the plurality of cylinder units comprises a cylinder, an intake port connected to the cylinder, an intake valve located between the cylinder and the intake port, a sensor for measuring the pressure inside the cylinder, and a fuel injector for injecting fuel. The controller detects a cylinder unit where a weak flame is occurring based on the pressure detected by the sensor, and stops fuel injection from the fuel injector to the cylinder unit where the weak flame is occurring for a predetermined period of time after the detection of the weak flame. A gas engine in which the controller detects the occurrence of a weak flame by detecting that the difference ΔP = P(θ) - P(-θ) is greater than or equal to a first threshold T1 and less than or equal to a second threshold T2, when P(-θ) is the pressure in the cylinder during the compression stroke when the crank angle is a predetermined angle θ before top dead center, and P(θ) is the pressure in the cylinder during the combustion stroke when the crank angle is a predetermined angle θ after top dead center. [Explanation of Symbols]

[0064] 2, 40, 46, 52, 58... Gas engines 4. Compressor 6. Intake passage 8, 42, 48, 54, 60... Manifold 10... Cylinder 12. Exhaust passage 14. Controller 16. Intake port 18...fuel injector 20. Intake valve 22...Igniter 28. Pressure sensor 30 pistons 32, 44, 50, 56, 62... Cylinder Units

Claims

1. It comprises multiple cylinder units, a manifold that supplies air to the multiple cylinder units, and a controller. Each of the plurality of cylinder units comprises a cylinder, an intake port connected to the cylinder, an intake valve located between the cylinder and the intake port, a sensor for measuring the pressure inside the cylinder, and a fuel injector for injecting fuel. The controller detects the cylinder unit in which flashback is occurring based on the pressure from the sensor, Determination of a cylinder unit to be stopped, targeting cylinder units other than the cylinder unit in which the aforementioned flashback occurred, A gas engine that, after detecting the flashback, stops fuel injection from the fuel injector to the cylinder unit where the flashback is occurring, and also stops fuel injection from the fuel injector to any stopped cylinder unit if such a cylinder unit exists, for a predetermined period of time.

2. The plurality of cylinder units are arranged in one or two rows along the manifold, The gas engine according to claim 1, wherein the controller is located downstream of the cylinder unit in the manifold from the cylinder unit in which the flashback was detected, and the cylinder unit adjacent to the cylinder unit in which the flashback was detected is designated as the stopped cylinder unit.

3. The gas engine according to claim 1 or 2, wherein the plurality of cylinder units are arranged in two rows along the manifold, with each cylinder unit in one row facing a corresponding cylinder unit in the other row, and the controller designates the cylinder unit facing the cylinder unit where the flashback was detected, or the cylinder unit adjacent to the cylinder unit facing the cylinder unit where the flashback was detected on the downstream side of the airflow in the manifold, as the stopped cylinder unit.

4. The gas engine according to claim 1 or 2, wherein the controller detects flashback by detecting that the pressure in the cylinder exceeds a predetermined threshold during the opening period of the intake valve, or by detecting that the pressure in the cylinder falls outside a predetermined range during the compression stroke.

5. The controller further performs the following: detection of a cylinder unit where a weak flame is occurring based on the pressure detected by the sensor, and stopping fuel injection from the fuel injector to the cylinder unit where the weak flame is occurring for a predetermined period of time after the detection of the weak flame. The gas engine according to claim 1 or 2, wherein the controller detects the occurrence of a weak flame by detecting that the difference ΔP = P(θ) - P(-θ) is greater than or equal to a first threshold T1 and less than or equal to a second threshold T2, when P(-θ) is the pressure in the cylinder during the compression stroke when the crank angle is a predetermined angle θ before top dead center, and P(θ) is the pressure in the cylinder during the combustion stroke when the crank angle is a predetermined angle θ after top dead center.

6. It comprises multiple cylinder units, a manifold that supplies air to the multiple cylinder units, and a controller. Each of the plurality of cylinder units comprises a cylinder, an intake port connected to the cylinder, an intake valve located between the cylinder and the intake port, a sensor for measuring the pressure inside the cylinder, and a fuel injector for injecting fuel. The controller detects a cylinder unit where a weak flame is occurring based on the pressure detected by the sensor, and stops fuel injection from the fuel injector to the cylinder unit where the weak flame is occurring for a predetermined period of time after the detection of the weak flame. A gas engine in which the controller detects the occurrence of a weak flame by detecting that the difference ΔP = P(θ) - P(-θ) is greater than or equal to a first threshold T1 and less than or equal to a second threshold T2, when the pressure in the cylinder during the compression stroke, when the crank angle is a predetermined angle θ before top dead center, is P(-θ), and the pressure in the cylinder during the combustion stroke, when the crank angle is a predetermined angle θ after top dead center, is P(θ).

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