Gas engine system and control method therefor

Abstract

To provide a gas engine system and a control method therefor capable of achieving appropriate combustion in a combustion chamber when two types of gaseous fuels with different ignition properties are mixed in advance at an arbitrary ratio and supplied to a gas engine in the gas engine comprising an auxiliary chamber.SOLUTION: A gas engine system comprises a gas engine, a mixer that mixes a first gaseous fuel with a second gaseous fuel that is more ignitable than the first fuel, and a processing circuit. When a proportion of the second fuel in the mixed fuel gas is within a predetermined range, the processing circuit controls an auxiliary gas supply regulator so that an amount of mixed fuel gas supplied to an auxiliary chamber decreases as the proportion of the second fuel increases.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a gas engine system and a control method thereof. [Background technology]

[0002] Gas engines that use gaseous fuel employ a lean-burn system to achieve high efficiency. Furthermore, gas engines employing the lean-burn system may have a pre-chamber separate from the combustion chamber to prevent misfires, a phenomenon in which fuel gas supplied to the combustion chamber does not burn, and to stabilize ignition. Ignition can be stabilized by generating a flame in the pre-chamber separate from the combustion chamber.

[0003] The following Patent Document 1 describes a gas engine equipped with a pre-chamber, in which the amount of fuel supplied to the pre-chamber is controlled according to the properties of the gaseous fuel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6002234 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in a gas engine equipped with a pre-chamber, when two types of gaseous fuels with different ignition properties are mixed in advance at an arbitrary ratio and supplied to the gas engine, a control mode different from that of Patent Document 1 is desired.

[0006] The present disclosure aims to provide a gas engine system and a control method thereof that can achieve appropriate combustion in a combustion chamber when two types of gaseous fuel with different ignition properties are pre-mixed in any ratio and supplied to a gas engine equipped with a pre-chamber. [Means for solving the problem]

[0007] A gas engine system according to one embodiment of the present disclosure includes a gas engine, a mixer that mixes a first gaseous fuel with a second gaseous fuel that is more ignitable than the first fuel, and a processing circuit. The gas engine includes a cylinder, a cylinder head that covers the cylinder, a piston that slides within the cylinder, an auxiliary chamber that is connected to a combustion chamber defined by the cylinder head and the piston, a main gas supply regulator that supplies mixed fuel gas to an air intake passage connected to the combustion chamber or to the combustion chamber, and an auxiliary gas supply regulator that supplies the mixed fuel gas to the auxiliary chamber. When the proportion of the second fuel in the mixed fuel gas is within a predetermined range, the processing circuit controls the auxiliary gas supply regulator so that the amount of mixed fuel gas supplied to the auxiliary chamber decreases as the proportion of the second fuel increases.

[0008] A control method for a gas engine system according to another aspect of the present disclosure is a control method for a gas engine system in which a gas engine including a cylinder, a cylinder head covering the cylinder, a piston sliding within the cylinder, an auxiliary chamber connected to a combustion chamber partitioned by the cylinder head and the piston, a main gas supply regulator supplying mixed fuel gas to an air intake passage connected to the combustion chamber or to the combustion chamber, and an auxiliary gas supply regulator supplying the mixed fuel gas to the auxiliary chamber, mixes a first gaseous fuel with a second gaseous fuel that is more ignitable than the first fuel, and then supplies the mixed fuel gas to the gas engine, wherein, when the proportion of the second fuel in the mixed fuel gas is within a predetermined range, the auxiliary gas supply regulator is controlled so that the amount of mixed fuel gas supplied to the auxiliary chamber is reduced as the proportion of the second fuel is greater. [Effects of the Invention]

[0009] According to the present disclosure, in a gas engine equipped with a pre-chamber, when two types of gaseous fuels with different ignition properties are mixed in advance at an arbitrary ratio and supplied to the gas engine, appropriate combustion can be achieved in the combustion chamber. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side cross-sectional view showing a schematic configuration of a gas engine included in a gas engine system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a schematic configuration of a gas engine system including the gas engine shown in FIG. [Figure 3] FIG. 3 is a time chart showing the control mode when the mixture ratio changes in this embodiment. [Figure 4] FIG. 4 is a diagram showing a schematic configuration of an engine system according to a first modification of the present embodiment. [Figure 5] FIG. 5 is a diagram showing a schematic configuration of an engine system according to a second modification of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings. In the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

[0012] Fig. 1 is a side cross-sectional view showing a schematic configuration of a gas engine included in a gas engine system according to an embodiment of the present disclosure. The gas engine 1 includes a frame 2 including a crank chamber 21 that houses a crankshaft 22, and multiple cylinders 3. Note that Fig. 1 shows only one cylinder 3.

[0013] A cylinder head 4 is attached to the cylinder 3. The cylinder 3 is covered from above by the cylinder head. A piston 24 is disposed within the cylinder 3. The piston 24 slides within the cylinder 3. The piston 24 is connected to a crankshaft 22 by a rod 23. A combustion chamber 10 is formed between the cylinder head 4 and the piston 24. In other words, the combustion chamber 10 is defined by the cylinder head 4 and the piston 24.

[0014] An intake passage 41 and an exhaust passage 42 are formed in the cylinder head 4. In FIG. 1, the intake passage 41 and the exhaust passage 42 extend from the combustion chamber 10 in order to show the structure of the gas engine 1 in a schematic manner.

[0015] The cylinder head 4 is equipped with an intake valve 11 and an exhaust valve 12. The intake valve 11 opens and closes the opening of an intake passage 41 to the combustion chamber 10, and the exhaust valve 12 opens and closes the opening of an exhaust passage 42 to the combustion chamber 10. An intake pipe 13 is connected to the intake passage 41 of the cylinder head 4. An exhaust pipe 14 is connected to the exhaust passage 42 of the cylinder head 4.

[0016] A cylinder head cover 45 is attached to the cylinder head 4. On the opposite side of the cylinder head 4 from the cylinder 3, devices such as drive mechanisms that drive the intake valves 11 and exhaust valves 12 are arranged, and the cylinder head cover 45 covers these devices. Also, each cylinder head 4 is provided with a pressure sensor 31 that measures the pressure inside the combustion chamber 10, i.e., the in-cylinder pressure.

[0017] Furthermore, the gas engine 1 includes a main gas valve 51, an ignition device 7, and an auxiliary gas valve 61 for each cylinder 3. The main gas valve 51 is connected to a main gas pipe 52. The auxiliary gas valve 61 is connected to an auxiliary gas pipe 62. The main gas pipe 52 and the auxiliary gas pipe 62 are connected to a fuel gas supply pipe 53, which will be described later.

[0018] In this embodiment, a fuel injection nozzle extends from the main gas valve 51 into the intake passage 41 of the cylinder head 4, and when the main gas valve 51 opens, fuel gas is injected into the intake passage 41. The injection of fuel gas into the intake passage 41 is controlled by electrically controlling the main gas valve 51.

[0019] However, the tip of the fuel injection nozzle of the main gas valve 51 may be located inside the intake pipe 13, and the fuel gas may be injected into the intake pipe 13. Also, the main gas valve 51 may be fixed to the cylinder head 4. In this case, the fuel gas may be injected directly from the main gas valve 51 into the combustion chamber 10.

[0020] The ignition device 7 ignites, in the combustion chamber 10, a mixture of fuel gas injected from the main gas valve 51 and intake air supplied through the intake pipe 13. In this embodiment, the ignition device 7 includes an auxiliary chamber 70 and an ignition plug 73. The auxiliary chamber 70 communicates with the combustion chamber 10 via a nozzle hole. The ignition plug 73 is connected to an ignition coil 75.

[0021] In this embodiment, the air-fuel mixture is burned in the combustion chamber 10 by a lean burn method. The spark plug 73 ignites the mixture of fuel gas and air injected into the auxiliary combustion chamber 70 via the auxiliary gas valve 61, and the lean air-fuel mixture in the combustion chamber 10 is ignited by the flame from the nozzle hole.

[0022] The ignition device 7 extends from the cylinder head 4 through the cylinder head cover 45. Specifically, the ignition device 7 includes a rod-shaped auxiliary chamber holder 72 that extends from the inside to the outside of the cylinder head 4 along an extension of the center line of the cylinder 3, and a partition wall 71 that surrounds the auxiliary chamber 70 together with the tip end surface of the auxiliary chamber holder 72. A part of the partition wall 71 protrudes into the combustion chamber 10, and the above-mentioned injection hole is formed in this protruding portion.

[0023] The pre-chamber holder 72 has a through-hole formed therein that extends in the axial direction of the pre-chamber holder 72. An ignition plug 73 is disposed in this through-hole so as to partially protrude into the pre-chamber 70. In this embodiment, the method of igniting the pre-chamber is exemplified by a spark ignition system using the spark plug 73, but instead, the fuel gas in the pre-chamber 70 may be ignited by an ignition device that employs other ignition systems, such as pilot ignition using fuel oil or laser ignition.

[0024] The auxiliary gas valve 61 is disposed in the cylinder head 4. As shown in FIG. 1, the auxiliary gas valve 61 is attached to the top surface of the cylinder head 4. Alternatively, the auxiliary gas valve 61 may be attached to the side surface of the cylinder head 4.

[0025] The auxiliary gas valve 61 is connected to the auxiliary chamber 70 via a fuel supply passage 60 formed in the cylinder head 4 and the auxiliary chamber holder 72. The injection of fuel gas into the auxiliary chamber 70 is controlled by electrically controlling the auxiliary gas valve 61. The auxiliary gas valve 61 may also be arranged to inject fuel gas directly into the auxiliary chamber 70.

[0026] Fig. 2 is a diagram showing a schematic configuration of a gas engine system including the gas engine shown in Fig. 1. The gas engine 1 has a plurality of cylinders 3 arranged in a single row in the axial direction of the crankshaft 22. Alternatively, the plurality of cylinders 3 may be arranged in two rows in a V shape when viewed from the axial direction of the crankshaft 22.

[0027] The gas engine 1 includes an intake manifold 15 extending in the direction in which the cylinders 3 are aligned, and each intake pipe 13 connects the intake manifold 15 to an intake passage 41 in the corresponding cylinder head 4. Similarly, each exhaust pipe 14 connects an exhaust manifold 16 extending in the direction in which the cylinders 3 are aligned to an exhaust passage 42 in the corresponding cylinder head 4.

[0028] In this embodiment, the intake manifold 15 and the exhaust manifold 16 are arranged on the same side of the cylinder row. However, the intake manifold 15 and the exhaust manifold 16 may be arranged on opposite sides of the cylinder row, with the intake passage 41 and the exhaust passage 42 extending in opposite directions from the combustion chamber 10.

[0029] The gas engine 1 further includes a recirculation path 17 that returns a portion of the exhaust gas passing through the exhaust manifold 16 to the intake manifold 15. A heat exchanger 18 that cools the exhaust gas passing through the recirculation path 17 is disposed in the recirculation path 17. A return amount adjustment valve 19 that adjusts the amount of the portion of the exhaust gas returned to the intake manifold 15 is also disposed in the recirculation path 17. Note that in the example shown in FIG. 2, the return amount adjustment valve 19 is disposed downstream of the heat exchanger 18 in the recirculation path 17, i.e., at a position close to the intake manifold 15 relative to the heat exchanger 18. Alternatively, the return amount adjustment valve 19 may be disposed upstream of the heat exchanger 18 in the recirculation path 17, i.e., at a position close to the exhaust manifold 16 relative to the heat exchanger 18.

[0030] By opening the return amount adjustment valve 19 and sending the exhaust gas to the intake manifold 15 through the recirculation path 17, the oxygen concentration of the intake air in the intake manifold 15 decreases. In other words, the return amount adjustment valve 19 functions as an oxygen supply amount regulator that adjusts the amount of oxygen supplied to the gas engine 1.

[0031] In this embodiment, the gas engine system 100 includes the gas engine 1, a mixer 8 that mixes fuel gases, and a controller 9. The mixer 8 is connected to a first fuel supply source 89 and a second fuel supply source 90.

[0032] The first fuel supply source 89 supplies a gaseous first fuel to the gas engine system 100. The first fuel is selected from, for example, natural gas, ammonia, methane, butane, propane, etc. The second fuel supply source 90 supplies a gaseous second fuel to the gas engine system 100. The second fuel is a gas that is more ignitable than the first fuel. The second fuel is selected from, for example, hydrogen, acetylene, ethylene oxide, etc. Such a second fuel may be defined as a fuel having a lower minimum ignition energy than the first fuel or a wider explosion range of flammable gas than the first fuel. The explosion range of flammable gas is defined as the range between the lower explosion limit and the upper explosion limit.

[0033] The first fuel supply source 89 and the mixer 8 are connected by a first fuel gas line 81 so as to be able to deliver the first fuel. The second fuel supply source 90 and the mixer 8 are connected by a second fuel gas line 82 so as to be able to deliver the second fuel. The mixer 8 mixes the first fuel delivered from the first fuel supply source 89 with the second fuel delivered from the second fuel supply source 90 to generate fuel gas to be supplied to the gas engine 1. Although FIG. 4 does not show a structure for actively mixing the two fuels in the mixer 8, the mixer 8 may include a structure for promoting mixing and stirring, such as a static mixer. A fuel gas supply pipe 53 is connected to the mixer 8. The mixed fuel gas is supplied to the main gas pipe 52 and the auxiliary gas pipe 62 of each cylinder 3 of the gas engine 1 through the fuel gas supply pipe 53.

[0034] In this embodiment, the auxiliary gas valve 61 is an auxiliary gas supply regulator 64 that can adjust the amount of auxiliary gas supplied to the auxiliary chamber 70. That is, the longer the opening period of the auxiliary gas valve 61, the greater the amount of auxiliary gas supplied, and the shorter the opening period, the less the amount of auxiliary gas supplied. Similarly, the main gas valve 51 is a main gas supply regulator 54 that can adjust the amount of main gas supplied to the gas supply path 41.

[0035] The mixer 8 further includes a first on-off valve 83, a first flow rate adjustment valve 84, a first flow meter 85, a second on-off valve 86, a second flow rate adjustment valve 87, and a second flow meter 88. The first on-off valve 83 switches between supplying and cutting off the first fuel from a first fuel supply source 89 to a first fuel gas line 81. The first flow rate adjustment valve 84 adjusts the flow rate of the first fuel flowing through the first fuel gas line 81. The first flow meter 85 measures the flow rate of the first fuel flowing through the first fuel gas line 81. The second on-off valve 86 switches between supplying and cutting off the second fuel from a second fuel supply source 90 to a second fuel gas line 82. The second flow rate adjustment valve 87 adjusts the flow rate of the second fuel flowing through the second fuel gas line 82. The second flow meter 88 measures the flow rate of the second fuel flowing through the second fuel gas line 82.

[0036] The mixture ratio of the mixed fuel gas generated in the mixer 8 changes when the flow rate of the first fuel is adjusted by the first flow rate adjustment valve 84, when the flow rate of the second fuel is adjusted by the second flow rate adjustment valve 87, or when both are adjusted. Depending on the balance of the calorific values ​​of the first and second fuels and the selection of the capacity of the flow rate adjustment valves, it may be possible to obtain a desired mixture ratio without installing either the first fuel adjustment valve or the second fuel adjustment valve. In this embodiment, the mixture ratio of the fuel gas is defined as the proportion of the second fuel in the mixed fuel gas. However, it is obvious that the same effect can be obtained even when the mixture ratio of the fuel gas is defined as the proportion of the first fuel in the mixed fuel gas. In other words, the mixture ratio acquired by the controller 9 is not limited to a value indicating the proportion of the second fuel.

[0037] The controller 9 includes a processing circuit 91 that performs various types of signal processing. The processing circuit 91 includes a computer such as a microcontroller, a personal computer, or a PLC (Programmable Logic Controller). More specifically, the processing circuit 91 includes a processor, a memory, and peripheral circuits. The processor includes, for example, a CPU or an MPU. The memory includes, for example, a ROM, a RAM, a register, non-volatile storage, etc. The peripheral circuits include an input / output interface, etc. The controller 9 can be connected to an operation input device that operates the gas engine 1, a monitor that displays the control status, a speaker that outputs audio, etc.

[0038] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, 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 circuitry. In this specification, a circuit, unit, means, or module is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the circuit, unit, or means is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0039] A control program for controlling the gas engine 1 is stored in the memory of the controller 9. The controller 9 controls the gas engine 1 based on the control program. In this embodiment, the controller 9 receives a detection signal D1 from the first flow meter 85 of the mixer 8, a detection signal D2 from the second flow meter 88, and a detection signal D3 from the pressure sensor 31. The controller 9 also sends a control signal C1 to the first flow rate adjustment valve 84 of the mixer 8, a control signal C2 to the second flow rate adjustment valve 87, a control signal C3 to the auxiliary gas valve 61 which is the auxiliary gas supply regulator 64, a control signal C4 to the ignition coil 75, and a control signal C5 to the return rate adjustment valve 19 which is the oxygen supply rate regulator.

[0040] The processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of sub-gas supplied corresponds to the mixture ratio of the mixed fuel gas supplied from the mixer 8. In doing so, the processing circuit 91 acquires the mixture ratio of the mixed fuel gas. The processing circuit 91 acquires the flow rate F1 of the first fuel from the first flow meter 85 and the flow rate F2 of the second fuel from the second flow meter 88. The processing circuit 91 calculates the mixture ratio F2 / (F1+F2) from the acquired flow rates F1 of the first fuel and F2 of the second fuel. When the mixture ratio is within a predetermined range, the processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of mixed fuel gas supplied to the sub-chamber decreases as the mixture ratio, i.e., the proportion of the second fuel, increases.

[0041] When the proportion of the highly ignitable second fuel in the mixed fuel gas supplied to the gas engine 1 is low, a flame is generated in the auxiliary chamber 70, thereby preventing misfires in the combustion chamber 10 and stabilizing ignition. On the other hand, when the proportion of the highly ignitable second fuel in the mixed fuel gas supplied to the gas engine 1 is high, abnormal combustion such as knocking may occur due to ignition in the auxiliary chamber 70. Therefore, when the proportion of the highly ignitable second fuel is high, the amount of auxiliary gas supplied to the auxiliary chamber 70 by the auxiliary gas supply regulator 64 is reduced, thereby increasing the proportion of the highly ignitable second fuel and suppressing the combustion rate in the auxiliary chamber 70.

[0042] The control mode in this embodiment will be described in more detail below. Fig. 3 is a time chart showing the control mode when the mixture ratio is changed in this embodiment. For ease of explanation, the example in Fig. 3 illustrates the case of a gas engine 1 including one cylinder 3. The same applies when the gas engine 1 includes multiple cylinders 3 as in Fig. 2.

[0043] The example in Figure 3 illustrates a case where the fuel gas supplied to the gas engine 1 is changed from a state where the first fuel is 100%, i.e., a mixing ratio of 0%, to a state where the second fuel is 100%, i.e., a mixing ratio of 100%, and then returned to a mixing ratio of 0%. Note that the same control is performed when the fuel gas mixing ratio before and after the change is other than 0% or 100%, so the general shape of the time chart in Figure 3 will be similar. In this embodiment, the mixing ratio is expressed as a volume ratio.

[0044] FIG. 3 shows, from top to bottom, a time chart of the fuel gas mixture ratio, a time chart of the auxiliary gas supply amount, a time chart of the ignition timing, a time chart of the knock occurrence rate, and a time chart of the intake air oxygen concentration.

[0045] The knock occurrence rate indicates the frequency of knocking in the gas engine 1, calculated from the combustion index value. In this embodiment, the combustion index is an index that can calculate the frequency of knocking or misfire in the gas engine 1. In this embodiment, the combustion index is the in-cylinder pressure measured by the pressure sensor 31. In this embodiment, when the fuel gas mixture ratio is constant and the engine is in a steady state, the target value of the knock occurrence rate is set to a predetermined steady value greater than 0% to increase the thermal efficiency of the gas engine 1. For example, when generating electricity using the rotational power of the gas engine 1, the steady value of the knock occurrence rate is set to increase the power generation efficiency. When the target value of the knock occurrence rate is a steady value, the processing circuit 91 controls the ignition coil 75 and adjusts the ignition timing of the spark plug 73 so that the knock occurrence rate maintains the target value. The intake air oxygen concentration indicates the oxygen concentration of the intake air passing through the intake manifold 15.

[0046] At time t1, the processing circuit 91 acquires an instruction to change the target value of the mixture ratio of fuel gas. As described above, the target value of the mixture ratio acquired by the processing circuit 91 up until time t1 was 0%, whereas the target value of the mixture ratio acquired by the processing circuit 91 at time t1 becomes 100%.

[0047] At this timing, the processing circuit 91 controls the ignition coil 75 to delay the ignition timing of the spark plug 73 prior to changing the amount of auxiliary gas supplied. The delay in the ignition timing reduces the knock rate. After the ignition timing is changed, i.e., at time t2 after the knock rate has decreased, the processing circuit 91 controls the mixer 8 based on the acquired target mixture ratio value. Based on the control signals C1 and C2 from the processing circuit 91, the first flow rate control valve 84, the second flow rate control valve 87, or both are adjusted, gradually changing the ratio of the first fuel and the second fuel supplied to the mixer 8.

[0048] As described above, when the mixture ratio is within a predetermined range, the processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of mixed fuel gas supplied to the sub-chamber decreases as the mixture ratio increases.

[0049] In the example of FIG. 3 , the predetermined range is set to a range in which the mixing ratio is greater than 20% and less than 80%. Therefore, if the sub-gas supply amount when the mixing ratio is 0% is defined as the reference supply amount, the target value of the sub-gas supply amount when the mixing ratio is equal to or less than 20%, which is the lower limit of the predetermined range, is maintained at this reference supply amount. In this embodiment, the processing circuit 91 sets the target value of the sub-gas supply amount as a percentage [%] of the reference supply amount. That is, when the mixing ratio is equal to or greater than 0% and equal to or less than 20%, the target value of the sub-gas supply amount is maintained at 100%. Furthermore, when the mixing ratio is equal to or greater than 80%, which is the upper limit of the predetermined range, the target value of the sub-gas supply amount is set to 0%. That is, when the mixing ratio is equal to or greater than the upper limit of the predetermined range, the processing circuit 91 controls the sub-gas supply regulator 64 to stop the supply of mixed fuel gas to the sub-chamber 70.

[0050] Furthermore, when the target mixing ratio is higher than the current mixing ratio, the processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of mixed fuel gas supplied to the sub-chamber 70 becomes the supply amount at the target mixing ratio before the mixing ratio reaches the target mixing ratio or the upper limit of the predetermined range. In the example of Fig. 3, the target mixing ratio is set to a value higher than the upper limit of the predetermined range. Therefore, the processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of mixed fuel gas supplied to the sub-chamber 70 becomes the supply amount at the upper limit before the mixing ratio reaches 80%, which is the upper limit of the predetermined value.

[0051] Therefore, in the example of FIG. 3 , the sub-gas supply rate reaches 0% at time t4, before time t5, when the mixing ratio reaches 80%, the upper limit of the predetermined range. The mixing ratio then reaches 100%, the target mixing ratio, at time t6. By time t2, the processing circuit 91 calculates the time required for the actual mixing ratio to reach the target mixing ratio or the upper limit of the predetermined range, based on the difference between the current mixing ratio and the target mixing ratio and the amount of change in the mixing ratio per unit time. The amount of change in the mixing ratio per unit time is predetermined based on the capacity of the flow control valves 84 and 87. Based on the amount of change in the mixing ratio per unit time, the processing circuit 91 sets the target mixing ratio for each unit time from time t2 to time t6 and controls the flow control valves 84 and 87 so that the mixing ratio calculated from the flow rates obtained by the flow meters 85 and 88 reaches the corresponding target value.

[0052] Furthermore, the processing circuit 91 calculates the amount of change in the sub gas supply amount per unit time so that the sub gas supply amount reaches the target value at time t4, a predetermined time before time t5 after the calculated arrival time has elapsed from time t2. In the example of FIG. 3, the processing circuit 91 changes the sub gas supply amount from time t3, which is after time t2. Time t3 is the time when the mixture ratio reaches 20%, the lower limit of the predetermined range. Therefore, the processing circuit 91 calculates the amount of change in the sub gas supply amount per unit time so that the sub gas supply amount reaches the target value at time t4 by changing the sub gas supply amount from time t3. In other words, the amount of change in the sub gas supply amount per unit time corresponds to the slope from time t3 to time t4 in the time chart of the sub gas supply amount in FIG. 3.

[0053] The processing circuit 91 sets a target value for the sub-gas supply amount for each unit time from time t3 to time t4 based on the calculated change in the sub-gas supply amount per unit time, and controls the sub-gas supply regulator 64 so that the sub-gas supply amount reaches the corresponding target value for each unit time.

[0054] During the period from time t3 to time t4 when the auxiliary gas supply amount is changed, the processing circuit 91 controls the return amount adjustment valve 19, which is an oxygen supply amount regulator, so that the amount of oxygen supplied to the gas engine 1 decreases as the mixing ratio in the fuel gas increases.

[0055] As a result, after time t4, the secondary gas supply amount is maintained at 0%, but the mixture ratio further increases, resulting in an increased knock rate. After time t6, when the mixture ratio reaches the mixture ratio target value, the processing circuit 91 advances the ignition timing so that the knock rate reaches a steady value. This further increases the knock rate.

[0056] The processing circuit 91 delays the ignition timing of the spark plug 73 while the mixture ratio is being changed compared to when the mixture ratio is constant. On the other hand, when the mixture ratio is in a constant steady state, that is, during the period up to time t1 and the period from time t7 to time t8 in Figure 3, the processing circuit 91 controls the ignition timing so that the knock occurrence rate remains constant at a steady value.

[0057] At time t8, the processing circuit 91 again acquires an instruction to change the target value of the mixture ratio of fuel gas. In the example of Fig. 3, the target value of the mixture ratio acquired by the processing circuit 91 during the period from time t7 to time t8 was 100%, but at time t8, the target value of the mixture ratio acquired by the processing circuit 91 becomes 0%.

[0058] At this timing, the processing circuit 91 controls the ignition coil 75 to delay the ignition timing of the spark plug 73 prior to changing the amount of auxiliary gas supplied. Retarding the ignition timing reduces the knock occurrence rate. At time t9 after the ignition timing is changed, the processing circuit 91 controls the mixer 8 based on the acquired target mixture ratio value. Based on the control signals C1 and C2 from the processing circuit 91, the first flow rate control valve 84, the second flow rate control valve 87, or both are adjusted, thereby gradually changing the ratio of the first fuel and the second fuel supplied to the mixer 8.

[0059] When the mixture ratio is within a predetermined range, the processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of mixed fuel gas supplied to the sub-chamber increases as the mixture ratio decreases.

[0060] 3, the predetermined range is set to a range in which the mixture ratio is greater than 20% and less than 80%. Therefore, the processing circuit 91 maintains the sub-gas supply amount at 0% from time t9 to time t10, when the mixture ratio falls below 80%, which is the upper limit of the predetermined range. Note that, during the period from time t9 to time t10, the decrease in the mixture ratio causes the knock occurrence rate to decrease.

[0061] Furthermore, when the target mixing ratio value is smaller than the current mixing ratio, the processing circuit 91 controls the sub-gas supply regulator 64 so that the sub-gas supply amount reaches the supply amount at the target mixing ratio value before the mixing ratio reaches the target mixing ratio value or the lower limit of the predetermined range. In the example of Fig. 3, the sub-gas supply amount reaches the supply amount at the target mixing ratio value, i.e., 100%, at time t11, before time t12, when the mixing ratio reaches 20%, the lower limit of the predetermined range. At time t13, after the mixing ratio reaches the lower limit of the predetermined range, the fuel gas mixing ratio reaches 0%, the target mixing ratio value.

[0062] Furthermore, during the period from time t10 to time t11 when the auxiliary gas supply amount is changed, the processing circuit 91 controls the return amount adjustment valve 19, which is an oxygen supply amount adjuster, so that the amount of oxygen supplied to the gas engine 1 increases as the mixing ratio decreases.

[0063] After time t13 when the mixture ratio reaches the target mixture ratio, the processing circuit 91 advances the ignition timing to change it to the value when the mixture ratio is 0%, which increases the knock occurrence rate and returns it to the state it was in before time t1.

[0064] According to the above configuration, when the proportion of the highly ignitable second fuel in the mixed fuel gas supplied to the gas engine 1 is low, a flame is generated in the auxiliary chamber 70, thereby preventing misfires in the combustion chamber 10 and stabilizing ignition. On the other hand, when the proportion of the highly ignitable second fuel in the mixed fuel gas supplied to the gas engine 1 is high, the amount of auxiliary gas supplied to the auxiliary chamber 70 by the auxiliary gas supply regulator 64 is reduced, thereby increasing the proportion of the highly ignitable second fuel, and preventing the flame generated in the auxiliary chamber 70 from becoming large. As a result, when two types of gaseous fuels with different ignitability are pre-mixed at any ratio and supplied to the gas engine 1 in a gas engine 1 equipped with an auxiliary chamber 70, appropriate combustion in the combustion chamber 10 can be achieved.

[0065] Furthermore, according to this embodiment, when the proportion of the second fuel is increased, the sub gas supply amount reaches the supply amount for the target mixture ratio before the mixture ratio of fuel gas reaches the target value or the upper limit value of a predetermined range. By advancing the timing to reduce the sub gas supply amount during a transition period when the fuel gas is changing in a direction that increases ignitability, the probability of abnormal combustion occurring can be further reduced. Furthermore, according to this embodiment, when the proportion of the second fuel is reduced, the sub gas supply amount reaches the supply amount for the target mixture ratio before the mixture ratio of fuel gas reaches the target value or the lower limit value of a predetermined range. By advancing the timing to increase the sub gas supply amount during a transition period when the fuel gas is changing in a direction that decreases ignitability, the probability of misfire occurring can be reduced.

[0066] Furthermore, according to this embodiment, when the mixture ratio of the fuel gas is equal to or greater than the upper limit of a predetermined range, the amount of sub-gas supplied becomes 0. This makes it possible to suppress the occurrence of abnormal combustion even when the second fuel, which has high ignition properties, becomes dominant in the mixed fuel gas.

[0067] Furthermore, according to this embodiment, the ignition timing of the spark plug 73 while the mixture ratio of fuel gas is being changed is delayed compared to when the mixture ratio is constant. This reduces the probability of abnormal combustion occurring while the mixture ratio is being changed, and enables stable changes to be made to the mixture ratio while the gas engine 1 is running.

[0068] Furthermore, according to this embodiment, when the proportion of the second fuel with high ignition properties is high in the mixed fuel gas supplied to the gas engine 1, the amount of oxygen supplied to the gas engine 1 is reduced compared to when the proportion of the second fuel with high ignition properties is low. This makes it possible to suppress the combustion speed in the combustion chamber 10 and the auxiliary chamber 70, and ultimately to suppress abnormal combustion.

[0069] With this configuration, even when hydrogen or the like, which has a very high ignition property, is used as the second fuel, proper combustion can be achieved.

[0070] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various improvements, changes, and modifications are possible within the scope of the spirit of the present disclosure.

[0071] [Other embodiments] For example, in the above embodiment, the lower limit value of the predetermined range of the mixing ratio for controlling the sub-gas supply regulator 64 in accordance with the mixing ratio of the fuel gas is 20% and the upper limit value is 80%, but the lower and upper limits are not limited to these values. For example, the lower limit value of the predetermined range of the mixing ratio can be selected from the range of 20% to 33%, and the upper limit value of the predetermined range of the mixing ratio can be selected from the range of 66% to 95%. Alternatively, the lower limit value of the predetermined range of the mixing ratio may be 0% or the upper limit value of the predetermined range of the mixing ratio may be 100%. In other words, the amount of sub-gas supply does not need to be constant in the high mixing ratio range or the low mixing ratio range.

[0072] In the above embodiment, when the sub-gas supply amount is decreased or increased, an example is shown in which the amount is changed linearly as shown in FIG. 3, but the amount may be changed so as to include a curved change during at least a part of the period during which the sub-gas supply amount is changed.

[0073] Furthermore, in the above embodiment, the gas engine 1 is illustrated as having a recirculation path 17, but the gas engine 1 does not necessarily have to have the recirculation path 17. In this case, the gas engine 1 may have another configuration as an oxygen supply regulator. For example, the gas engine 1 may be equipped with an inert gas supply regulator that supplies an inert gas to the intake manifold 15 or each intake pipe 13. By supplying the inert gas, the oxygen concentration of the intake air in the intake pipe 13 decreases. The inert gas may be selected from, for example, nitrogen, argon, a rare gas, carbon dioxide, etc.

[0074] In the above embodiment, the in-cylinder pressure detected by the pressure sensor 31 is used as a combustion index for calculating the frequency of knocking or misfire in the gas engine 1, but this is not limiting. For example, the combustion index may be cylinder acceleration or in-cylinder acoustic waves. Cylinder acceleration can be detected by mounting an acceleration sensor on the cylinder head 4. In-cylinder acoustic waves can be detected by mounting an acoustic sensor on the cylinder head 4.

[0075] Furthermore, in the above embodiment, an example has been shown in which the auxiliary gas supply regulator 64 for controlling the amount of auxiliary gas supplied is the auxiliary gas valve 61, but this is not limiting. FIG. 4 is a diagram showing a schematic configuration of an engine system in Modification 1 of this embodiment. Components similar to those in FIG. 2 are assigned the same reference numerals, and description thereof will be omitted. For example, as shown in FIG. 4, an auxiliary gas supply pressure regulation valve 63 that regulates the supply pressure of fuel gas supplied to the auxiliary gas valve 61 may be disposed in the auxiliary gas piping 62. The auxiliary gas supply regulator 64 may include the auxiliary gas supply pressure regulation valve 63. The auxiliary gas supply pressure regulation valve 63 increases the amount of auxiliary gas supplied as the auxiliary gas supply pressure increases, and decreases the amount of auxiliary gas supplied as the auxiliary gas supply pressure decreases. Note that a main gas supply pressure regulation valve that regulates the supply pressure of fuel gas supplied to the main gas valve 51 may be disposed in the main gas piping 52.

[0076] Furthermore, the amount of sub-gas supplied may be controlled by combining the sub-gas supply pressure regulating valve 63 and the sub-gas valve 61. That is, the processing circuit 91 may control the amount of sub-gas supplied by combining the opening period of the sub-gas valve 61 and the supply pressure of the sub-gas passing through the sub-gas valve 61.

[0077] Fig. 5 is a diagram showing a schematic configuration of an engine system in Modification 2 of this embodiment. In the above embodiment, a configuration in which the main gas piping 52 and the auxiliary gas piping 62 for each cylinder 3 branch off from the fuel gas supply pipe 53 has been exemplified, but as shown in Fig. 5, the fuel gas supply pipe 53 may branch off into a main gas supply pipe 53a and an auxiliary gas supply pipe 53b, with the main gas piping 52 for each cylinder 3 connected to the main gas supply pipe 53a and the auxiliary gas piping 62 for each cylinder 3 connected to the auxiliary gas supply pipe 53b. In the example of Fig. 5, an auxiliary gas supply pressure regulating valve 63 may be provided in the auxiliary gas supply pipe 53b as an auxiliary gas supply regulator 64.

[0078] In addition to the control in the above embodiment, when the mixing ratio is being changed and the target value of the combustion index is constant, the processing circuit 91 may control the sub-gas supply regulator 64 so that the combustion index value maintains the target value. In the example of Fig. 3, this control may be executed between time t3 and time t4 and between time t10 and time t11.

[0079] In the above embodiment, the sub gas supply amount is increased or decreased in accordance with changes in the mixture ratio. However, in actual control, there is a possibility that the sub gas supply amount for a given mixture ratio may not be an appropriate value. The target value of the knock occurrence rate is constant near 0 because the ignition timing is delayed when the mixture ratio is changed. However, fluctuations in the sub gas supply amount may cause the knock occurrence rate to change during that period. Therefore, by adjusting the sub gas supply amount in accordance with changes in the combustion index value, the sub gas supply amount can be corrected to a value corresponding to changes in the mixture ratio. Note that if the gas engine 1 has multiple cylinders 3, this control is performed for each cylinder 3.

[0080] The amount of sub-gas supply may also be controlled taking into consideration the time it takes for the fuel gas mixed in the mixer 8 to reach the gas engine 1 through the fuel gas supply pipe 53. In this case, the processing circuit 91 may execute control of the sub-gas supply regulator 64 after a predetermined waiting time has elapsed since the timing when the target mixing ratio value changed. In this case, the waiting time is determined based on the time it takes for the mixed fuel gas to reach the gas engine 1 from the mixer 8.

[0081] If the distance between the mixer 8 and the gas engine 1 is long, even if the mixture ratio of the fuel gas changes in the mixer 8, the fuel gas after the mixture ratio change is not immediately supplied to the gas engine 1. For this reason, by executing control of the sub-gas supply regulator 64 after the waiting time has elapsed from the timing when the mixture ratio target value changed, it is possible to appropriately control the amount of sub-gas supplied according to the mixture ratio of the fuel gas actually supplied to the gas engine 1.

[0082] In the above embodiment, the mixing ratio acquired by the processing circuit 91 of the controller 9 is a value indicating the proportion of the second fuel, but as mentioned above, this is not limited to this, and the mixing ratio may be a value indicating the proportion of the first fuel. In this case, when the mixing ratio indicating the proportion of the first fuel is within a predetermined range, the processing circuit 91 controls the sub-gas supply regulator 64 so that the amount of mixed fuel gas supplied to the sub-chamber decreases as the mixing ratio decreases.

[0083] Furthermore, the gas engine system 100 of the present disclosure is applicable to various gas engine systems in which two types of fuel gas are mixed in a mixer 8 and then supplied to the gas engine 1, such as a gas engine system equipped with a gas engine 1 installed in a plant such as a power generation plant, or a gas engine system equipped with a gas engine 1 mounted on a mobile body such as a ship, vehicle, or aircraft.

[0084] In addition, in the above embodiment, an example was given of a configuration in which the processing circuit 91 in the controller 9 of the gas engine 1 controls the first flow control valve 84 and the second flow control valve 87, but the controller that controls the first flow control valve 84 and the second flow control valve 87 may be a controller separate from the controller 9 that controls the auxiliary gas supply regulator 64.

[0085] Furthermore, in the above embodiment, an example has been given in which the controller 9 of the gas engine 1 includes the processing circuit 91 of the gas engine system 100, but the processing circuit 91 that performs arithmetic processing for the gas engine system 100 may be configured as a processing circuit separate from the controller 9 of the gas engine 1. For example, the processing circuit 91 may be included in a management system that is higher than the gas engine 1 in a power generation plant or the like in which the gas engine 1 is installed. Also, for example, the processing circuit 91 may be included in an external computer such as a server that is communicatively connected to the controller 9 of the gas engine 1 via a communication network.

[0086] In addition, the control program for executing arithmetic processing in the processing circuit 91 of the gas engine system 100 in the above embodiment may be configured as a program product that is provided by downloading from an external computer or recorded on a recording medium, or may be configured as a computer product in which the control program is pre-installed.

[0087] Summary of this disclosure [Item 1] A gas engine system according to one embodiment of the present disclosure includes a gas engine, a mixer that mixes a first gaseous fuel with a second gaseous fuel that is more ignitable than the first fuel, and a processing circuit. The gas engine includes a cylinder, a cylinder head that covers the cylinder, a piston that slides within the cylinder, an auxiliary chamber that is connected to a combustion chamber defined by the cylinder head and the piston, a main gas supply regulator that supplies mixed fuel gas to the combustion chamber or an air intake passage connected to the combustion chamber, and an auxiliary gas supply regulator that supplies the mixed fuel gas to the auxiliary chamber. When the proportion of the second fuel in the mixed fuel gas is within a predetermined range, the processing circuit controls the auxiliary gas supply regulator so that the amount of mixed fuel gas supplied to the auxiliary chamber decreases as the proportion of the second fuel increases.

[0088] According to the above configuration, when the proportion of the highly ignitable second fuel in the mixed fuel gas supplied to the gas engine is low, a flame is generated in the auxiliary chamber, thereby preventing misfires in the combustion chamber and stabilizing ignition. On the other hand, when the proportion of the highly ignitable second fuel in the mixed fuel gas supplied to the gas engine is high, the auxiliary gas supply regulator reduces the amount of mixed fuel gas supplied to the auxiliary chamber, thereby increasing the proportion of the highly ignitable second fuel and preventing the flame generated in the auxiliary chamber from becoming large. This makes it possible to achieve appropriate combustion in the combustion chamber in a gas engine equipped with an auxiliary chamber when two types of gaseous fuels with different ignitability are pre-mixed at any ratio and supplied to the gas engine.

[0089] [Item 2] In the gas engine system of item 1, the processing circuit may control the mixer based on a target mixing ratio value for the proportion of the second fuel, and when the proportion of the second fuel at the target mixing ratio value is greater than the current proportion of the second fuel, control the sub-gas supply regulator so that the amount of the mixed fuel gas supplied to the sub-chamber becomes the supply amount at the target mixing ratio value before the proportion of the second fuel reaches the proportion of the second fuel at the target mixing ratio value or the upper limit of the predetermined range. This can further reduce the probability of abnormal combustion occurring by advancing the timing to reduce the amount of mixed fuel gas supplied to the sub-chamber during a transition period when the fuel gas is changing in a direction to increase ignitionability.

[0090] [Item 3] In the gas engine system of item 1 or 2, the processing circuit may control the mixer based on a target mixing ratio value for the proportion of the second fuel, and when the target mixing ratio value for the proportion of the second fuel is smaller than the current proportion of the second fuel, control the sub-gas supply regulator so that the amount of the mixed fuel gas supplied to the sub-chamber reaches the supply amount at the target mixing ratio value before the proportion of the second fuel reaches the proportion of the second fuel at the target mixing ratio value or the lower limit of the predetermined range. This can reduce the probability of misfire by advancing the timing to increase the amount of mixed fuel gas supplied to the sub-chamber during a transition period when the fuel gas is changing in a direction decreasing its ignitability.

[0091] [Item 4] In the gas engine system according to any one of items 1 to 3, the processing circuit may control the auxiliary gas supply regulator to stop the supply of the mixed fuel gas to the auxiliary chamber when the proportion of the second fuel is equal to or greater than the upper limit of the predetermined range. This makes it possible to suppress abnormal combustion even when the second fuel, which has high ignition properties, becomes dominant in the mixed fuel gas.

[0092] [Item 5] In the gas engine system of any one of items 1 to 4, the gas engine may include an ignition device for the pre-combustion chamber, and the processing circuit may delay the ignition timing of the ignition device while the proportion of the second fuel is being changed compared to when the proportion of the second fuel is constant. This reduces the probability of abnormal combustion occurring while the proportion of the second fuel is being changed, and makes it possible to stably change the proportion of the second fuel while the gas engine is operating.

[0093] [Item 6] The gas engine system according to any one of items 1 to 5 may further include an oxygen supply regulator that adjusts the amount of oxygen supplied to the gas engine, and the processing circuit may control the oxygen supply regulator so that the amount of oxygen supplied to the gas engine decreases as the proportion of the second fuel increases, when the proportion of the second fuel is within a predetermined range. This makes it possible to suppress the combustion speed in the combustion chamber and the auxiliary chamber, and thereby to suppress abnormal combustion.

[0094] [Item 7] In the gas engine system of any one of items 1 to 6, the processing circuit may acquire a combustion index value capable of calculating the frequency of knocking or misfire in the gas engine, and, when the proportion of the second fuel is being changed and the target value of the combustion index value is constant, control the sub-gas supply regulator so that the combustion index value maintains the target value. By adjusting the amount of mixed fuel gas supplied to the sub-chamber in accordance with changes in the combustion index value, even if the supply amount deviates from the value corresponding to the proportion of the second fuel, it is possible to correct the value to a value corresponding to the change in the proportion of the second fuel.

[0095] [Item 8] In the gas engine system of any one of items 1 to 7, the processing circuit may control the mixer based on a target mixing ratio value for the proportion of the second fuel, and may execute control of the sub-gas supply regulator after a predetermined waiting time has elapsed since the target mixing ratio value changed, the waiting time being determined based on the time it takes for the mixed fuel gas to reach the gas engine from the mixer. In this way, the control of the sub-gas supply regulator is executed after the waiting time has elapsed since the target mixing ratio value changed, so that the sub-gas supply amount can be appropriately controlled according to the mixing ratio of the fuel gas actually supplied to the gas engine.

[0096] [Item 9] In the gas engine system of any one of items 1 to 8, the second fuel may be hydrogen.

[0097] [Item 10] A control method for a gas engine system according to another aspect of the present disclosure is a control method for a gas engine system in which a gas engine including a cylinder, a cylinder head covering the cylinder, a piston sliding within the cylinder, an auxiliary chamber connected to a combustion chamber partitioned by the cylinder head and the piston, a main gas supply regulator supplying mixed fuel gas to an air intake passage connected to the combustion chamber or to the combustion chamber, and an auxiliary gas supply regulator supplying the mixed fuel gas to the auxiliary chamber, mixes a first gaseous fuel with a second gaseous fuel that is more ignitable than the first fuel, and then supplies the mixed fuel gas to the gas engine, wherein, when the proportion of the second fuel in the mixed fuel gas is within a predetermined range, the auxiliary gas supply regulator is controlled so that the amount of mixed fuel gas supplied to the auxiliary chamber is reduced as the proportion of the second fuel is greater. [Explanation of symbols]

[0098] 1 gas engine 3 cylinders 4. Cylinder head 8 mixer 10 Combustion chamber 19 Return volume adjustment valve (oxygen supply volume regulator) 24 pistons 41 Air supply path 54 Main gas supply regulator 64 Sub gas supply regulator 70 Antechamber 73 Spark plug 91 Processing circuit 100 Gas Engine System

Claims

1. Gas engine and a mixer that mixes a gaseous first fuel with a gaseous second fuel that has higher ignition ability than the first fuel; processing circuitry; The gas engine is A cylinder; a cylinder head covering the cylinder; a piston that slides within the cylinder; an auxiliary chamber communicating with a combustion chamber defined by the cylinder head and the piston; a main gas supply regulator that supplies mixed fuel gas to an air intake passage connected to the combustion chamber or to the combustion chamber; an auxiliary gas supply regulator for supplying the mixed fuel gas to the auxiliary chamber, The processing circuitry and controlling the auxiliary gas supply regulator so that, when a ratio of the second fuel in the mixed fuel gas is within a predetermined range, the amount of the mixed fuel gas supplied to the auxiliary chamber is reduced as the ratio of the second fuel increases.

2. The processing circuitry controlling the mixer based on a target mixing ratio value for the proportion of the second fuel; 2. The gas engine system according to claim 1, wherein, when the proportion of the second fuel in the target mixing ratio value is larger than the current proportion of the second fuel, the sub-gas supply regulator is controlled so that the amount of the mixed fuel gas supplied to the sub-chamber becomes the supply amount at the target mixing ratio value before the proportion of the second fuel reaches the proportion of the second fuel in the target mixing ratio value or an upper limit value of the predetermined range.

3. The processing circuitry controlling the mixer based on a target mixing ratio value for the proportion of the second fuel; 3. The gas engine system according to claim 1, wherein, when the proportion of the second fuel in the target mixing ratio value is smaller than the current proportion of the second fuel, the sub-gas supply regulator is controlled so that the amount of the mixed fuel gas supplied to the sub-chamber reaches the supply amount at the target mixing ratio value before the proportion of the second fuel reaches the proportion of the second fuel in the target mixing ratio value or a lower limit value of the predetermined range.

4. The processing circuitry 3. The gas engine system according to claim 1, wherein the auxiliary gas supply regulator is controlled to stop supplying the mixed fuel gas to the auxiliary chamber when the proportion of the second fuel is equal to or greater than an upper limit value of the predetermined range.

5. the gas engine includes an ignition device for the auxiliary chamber; The processing circuitry 3. The gas engine system according to claim 1, wherein the ignition timing of the ignition device is delayed while the proportion of the second fuel is being changed compared to when the proportion of the second fuel is constant.

6. an oxygen supply regulator that adjusts the amount of oxygen supplied to the gas engine; The processing circuitry 3. The gas engine system according to claim 1, wherein, when the proportion of the second fuel is within a predetermined range, the oxygen supply regulator is controlled so as to reduce the amount of oxygen supplied to the gas engine as the proportion of the second fuel increases.

7. The processing circuitry obtaining a combustion index value that allows calculation of the frequency of occurrence of knocking or misfire in the gas engine; 3. The gas engine system according to claim 1, wherein, when the proportion of the second fuel is being changed and the target value of the combustion index value is constant, the auxiliary gas supply regulator is controlled so that the combustion index value maintains the target value.

8. The processing circuitry controlling the mixer based on a target mixing ratio value for the proportion of the second fuel; and executing control of the sub-gas supply regulator after a predetermined waiting time has elapsed since the timing when the target mixing ratio value was changed.

3. The gas engine system according to claim 1, wherein the waiting time is determined based on the time it takes for the mixed fuel gas to reach the gas engine from the mixer.

9. The gas engine system according to claim 1 or 2, wherein the second fuel is hydrogen.

10. A control method for a gas engine system, comprising: a cylinder; a cylinder head covering the cylinder; a piston sliding inside the cylinder; an auxiliary chamber communicating with a combustion chamber defined by the cylinder head and the piston; a main gas supply regulator supplying mixed fuel gas to an intake passage connected to the combustion chamber or to the combustion chamber; and an auxiliary gas supply regulator supplying the mixed fuel gas to the auxiliary chamber, the method comprising: mixing a first gaseous fuel with a second gaseous fuel having a higher ignition ability than the first fuel; and then supplying the mixed fuel gas to the gas engine, the method comprising: a control method for a gas engine system, wherein, when a ratio of the second fuel in the mixed fuel gas is within a predetermined range, the auxiliary gas supply regulator is controlled so that the amount of the mixed fuel gas supplied to the auxiliary chamber is reduced as the ratio of the second fuel increases.

Images