Auxiliary chamber type gas engine

Abstract

When hydrocarbon gas and hydrogen gas are co-fired as fuel gas, a sub-chamber type gas engine capable of suppressing a decrease in thermal efficiency and an increase in NO x emission is provided. 【Solution means】A sub-chamber type gas engine configured to be capable of burning hydrocarbon gas and hydrogen gas as fuel gas includes a main combustion chamber forming portion that forms a main combustion chamber, a sub-combustion chamber forming portion that forms a sub-combustion chamber communicated with the main combustion chamber through at least one injection hole, at least one main ignition plug configured to ignite the fuel gas in the main combustion chamber, at least one sub-ignition plug configured to ignite the fuel gas in the sub-combustion chamber, and an ignition control device configured to control the ignition of each of the main ignition plug and the sub-ignition plug based on the co-firing rate of hydrogen gas.

Description

Technical Field

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

Background Art

[0002] Conventionally, a prechamber type gas engine including a main combustion chamber defined between a piston and a cylinder head, and a sub-combustion chamber communicated with the main combustion chamber through an injection hole has been known (for example, Patent Document 1). In the prechamber type gas engine, the fuel gas in the sub-combustion chamber is ignited by igniting an ignition plug disposed in the sub-combustion chamber. The combustion flame generated by ignition jets out from the injection hole to burn the air-fuel mixture in the main combustion chamber. In the prechamber type gas engine, hydrocarbon gas such as natural gas may be used as the fuel gas supplied to the sub-combustion chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, from the viewpoint of suppressing the CO 2 emission amount during hydrocarbon gas combustion, it is conceivable to burn a fuel gas containing hydrocarbon gas and hydrogen gas. However, Patent Document 1 does not disclose any findings regarding co-combustion of a fuel gas containing hydrocarbon gas and hydrogen gas in a prechamber type gas engine.

[0005] When the inventors studied, when burning a fuel gas containing hydrocarbon gas and hydrogen gas in the main combustion chamber by the combustion flame ejected from the sub-combustion chamber in a prechamber type gas engine, if the co-combustion rate of hydrogen is high, the combustion of the fuel gas in the main combustion chamber becomes steep, resulting in a decrease in thermal efficiency and NO xIt has been found that there is a risk of increasing the discharge amount.

[0006] In view of the above circumstances, at least some embodiments of the present invention, when co - burning hydrocarbon gas and hydrogen gas as fuel gas, can suppress a decrease in thermal efficiency and an increase in NO x emission amount, and provide a pre - chamber type gas engine.

Means for Solving the Problems

[0007] The pre - chamber type gas engine according to at least some embodiments of the present invention is configured to be able to burn hydrocarbon gas and hydrogen gas as fuel gas, a main combustion chamber forming part that forms a main combustion chamber, a sub - combustion chamber forming part that forms a sub - combustion chamber communicating with the main combustion chamber through at least one injection hole, at least one main ignition plug configured to ignite the fuel gas in the main combustion chamber, at least one sub - ignition plug configured to ignite the fuel gas in the sub - combustion chamber, an ignition control device configured to control the ignition of each of the main ignition plug and the sub - ignition plug based on the co - combustion rate of hydrogen gas, and includes.

Effects of the Invention

[0008] In at least some embodiments of the present invention, when co - burning hydrocarbon gas and hydrogen gas as fuel gas, a pre - chamber type gas engine that can suppress a decrease in thermal efficiency and an increase in NO x emission amount is provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0011] FIG. 1 is a schematic diagram showing the configuration of a prechamber type gas engine according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of a prechamber type gas engine according to another embodiment. Hereinafter, the prechamber type gas engine may be abbreviated as "gas engine".

[0012] The prechamber type gas engines 1 (1A, 1B) according to some embodiments are gas engines configured to be able to burn hydrocarbon gas and hydrogen gas as fuel gas. In the combustion of the fuel gas in the gas engines 1 (1A, 1B), the co-combustion ratio R of the hydrogen gas takes a value of 0% to 100%. That is, when R = 0%, the gas engines 1 (1A, 1B) are in a state of exclusive combustion of hydrocarbon gas, when 0% < R < 100%, they are in a state of co-combustion of hydrocarbon gas and hydrogen gas, and when R = 100%, they are in a state of exclusive combustion of hydrogen gas. The hydrocarbon gas is a gas mainly composed of methane gas, ethane gas, propane gas, etc. Examples of the hydrocarbon gas include natural gas.

[0013] In some embodiments, as shown in FIGS. 1 and 2, the gas engines 1 (1A, 1B) include a main combustion chamber forming portion 10, a sub-combustion chamber forming portion 30, at least one main ignition plug 40 (40A, 40B), at least one sub-ignition plug 50, and an ignition control device 60.

[0014] The main combustion chamber forming portion 10 is a member that forms the main combustion chamber MC. The main combustion chamber MC is a combustion chamber for burning the first air-fuel mixture A1. The first air-fuel mixture A1 is a gas containing an oxidizing gas and a hydrocarbon gas or a hydrogen gas. In one embodiment, the oxidizing gas is air. In this case, the ratio of air to fuel gas in the first air-fuel mixture A1 is set such that the ratio of air is higher than the stoichiometric air-fuel ratio. That is, the first air-fuel mixture is a lean air-fuel mixture.

[0015] As shown in FIG. 1, the main combustion chamber forming portion 10 forms an intake passage 12 that communicates with the main combustion chamber MC and guides the first air-fuel mixture A1 into the main combustion chamber MC. Further, the gas engines 1 (1A, 1B) further include an intake valve 70 that is disposed to be openable and closable with respect to the main combustion chamber MC for the intake passage 12. Similarly, the main combustion chamber forming portion 10 forms an exhaust passage 14 that communicates with the main combustion chamber MC and guides the exhaust A3 generated by the combustion in the main combustion chamber MC to the outside of the main combustion chamber MC. Further, the gas engines 1 (1A, 1B) further include an exhaust valve 72 that is disposed to be openable and closable with respect to the main combustion chamber MC for the exhaust passage 14.

[0016] In the embodiments shown in FIGS. 1 and 2, the main combustion chamber forming portion 10 includes a cylinder liner 16, a piston 18 that is reciprocally disposed within the cylinder liner 16, and a cylinder head 20 that forms the main combustion chamber MC between the cylinder liner 16 and the piston 18. That is, the main combustion chamber MC is formed by the cylinder liner 16, the piston 18, and the cylinder head 20. In the embodiment exemplarily shown in FIGS. 1 and 2, the main combustion chamber MC is defined by the crown surface 18a of the piston 18 and the wall surface 20a of the cylinder head 20. In other embodiments not shown, the main combustion chamber MC may be defined by the wall surface 16a of the cylinder liner 16, the crown surface 18a of the piston 18, and the wall surface 20a of the cylinder head 20.

[0017] The sub-combustion chamber forming portion 30 is a member that forms the sub-combustion chamber PC. The sub-combustion chamber PC communicates with the main combustion chamber MC through at least one injection hole 32 formed in the sub-combustion chamber forming portion 30. Note that the number of the injection holes 32 is not particularly limited, and one injection hole 32 may be formed in the sub-combustion chamber forming portion 30, or a plurality of injection holes 32 may be formed in the sub-combustion chamber forming portion 30. Further, the sub-combustion chamber PC is a combustion chamber for burning the second air-fuel mixture A2. The second air-fuel mixture A2 is a gas containing an oxidizing gas and a hydrocarbon gas. In one embodiment, the oxidizing gas is air. In this case, the ratio of air to the hydrocarbon gas in the second air-fuel mixture A2 is set to be close to the stoichiometric air-fuel ratio. In other embodiments not shown, the second air-fuel mixture A2 in the sub-combustion chamber PC may be a mixture obtained by mixing the first air-fuel mixture A1 flowing in through the injection hole 32 formed in the sub-combustion chamber forming portion 30 and the hydrocarbon gas. Note that the second air-fuel mixture A2 may be a mixture containing hydrogen gas or a mixture not containing hydrogen gas.

[0018] Note that, as shown in FIGS. 1 and 2, the sub-combustion chamber forming portion 30 forms an intake passage 34 that communicates with the sub-combustion chamber PC and guides the second air-fuel mixture A2 into the sub-combustion chamber PC. Further, the gas engine 1 (1A, 1B) further includes an intake valve 74 that is disposed to be able to open and close the intake passage 34 with respect to the sub-combustion chamber PC. In other embodiments not shown, the intake passage 34 may be a flow path for guiding fuel gas into the sub-combustion chamber PC.

[0019] In the embodiments shown in FIGS. 1 and 2, the sub-combustion chamber forming portion 30 is arranged such that the central axis O1 of the main combustion chamber MC and the central axis O2 of the sub-combustion chamber PC coincide. In other embodiments (not shown), the sub-combustion chamber forming portion 30 may be arranged in a state where the central axis O1 of the main combustion chamber MC and the central axis O2 of the sub-combustion chamber PC do not coincide.

[0020] At least one main ignition plug 40 (40A, 40B) is configured to ignite the fuel gas in the main combustion chamber MC. That is, the main ignition plug 40 (40A, 40B) is configured to ignite the hydrocarbon gas or hydrogen gas contained in the first air-fuel mixture A1 in the main combustion chamber MC.

[0021] In the embodiments shown in FIGS. 1 and 2, the main ignition plug 40 (40A, 40B) includes a main body portion 42 (42A, 42B) and an ignition portion 44 (44A, 44B) attached to the main body portion 42 (42A, 42B). The main body portion 42 (42A, 42B) is installed such that the ignition portion 44 (44A, 44B) is located in the main combustion chamber MC. The ignition portion 44 (44A, 44B) is not particularly limited and may be a spark plug that generates a spark discharge, or other known ignition techniques may be used. Although details will be described later, in the embodiment shown in FIG. 1, the main ignition plug 40 includes a central main ignition plug 40A. Similarly, in the embodiment shown in FIG. 2, the main ignition plug 40 includes an outer peripheral main ignition plug 40B.

[0022] At least one sub-ignition plug 50 is configured to ignite the fuel gas in the sub-combustion chamber PC. That is, the sub-ignition plug 50 is configured to ignite the hydrocarbon gas contained in the second air-fuel mixture A2 in the sub-combustion chamber PC. Although details will be described later, the sub-ignition plug 50 may ignite the first air-fuel mixture A1 that has flowed into the sub-combustion chamber PC from the injection hole 32 formed in the sub-combustion chamber forming portion 30.

[0023] In the embodiments shown in FIGS. 1 and 2, the sub-ignition plug 50 includes a main body portion 52 and an ignition portion 54 attached to the main body portion 52. The main body portion 52 is installed such that the ignition portion 54 is located within the sub-combustion chamber PC. The ignition portion 54 is not particularly limited and may be a spark plug that generates a spark discharge, or other known ignition technologies may be used.

[0024] The ignition control device 60 is configured to control the ignition of each of the main ignition plugs 40 (40A, 40B) and the sub-ignition plug 50 based on the mixing ratio R of hydrogen gas. Specifically, the ignition control device 60 is configured to execute control for igniting the main ignition plugs 40 (40A, 40B) or the sub-ignition plug 50, and control of the ignition timing of the main ignition plugs 40 (40A, 40B) and the sub-ignition plug 50. The mixing ratio R of hydrogen gas is the ratio of the heat amount of hydrogen gas to the heat amount of the entire fuel gas. The mixing ratio R of hydrogen gas may be calculated, for example, by measuring or estimating the flow rate of hydrocarbon gas supplied from a hydrocarbon gas supply source and the flow rate of hydrogen gas supplied from a hydrogen gas supply source.

[0025] As shown in FIGS. 1 and 2, the ignition control device 60 includes a processor 62 and a memory 64 as a configuration for controlling the ignition of each of the main ignition plugs 40 (40A, 40B) and the sub-ignition plug 50. The processor 62 is configured to refer to the ignition timing of the main ignition plugs 40 (40A, 40B) or the sub-ignition plug 50 recorded in the memory 64. Then, the processor 62 is configured to transmit a signal for causing ignition of the main ignition plugs 40 (40A, 40B) or the sub-ignition plug 50 according to the mixing ratio R of hydrogen gas. Note that the processor 62 is not particularly limited and may be, for example, a CPU (Central Processing Unit). Also, the memory 64 is not particularly limited and may be, for example, a RAM (Random Access Memory).

[0026] In the embodiment shown in FIGS. 1 and 2, the ignition control device 60 is connected to the main ignition plugs 40 (40A, 40B) via the first ignition line 66 and to the sub-ignition plug 50 via the second ignition line 68. The first ignition line 66 is a line for transmitting the signal generated by the ignition control device 60 to the main ignition plugs 40 (40A, 40B). Similarly, the second ignition line 68 is a line for transmitting the signal generated by the ignition control device 60 to the sub-ignition plug 50.

[0027] According to the above configuration, the ignition of each of the main ignition plugs 40 (40A, 40B) and the sub-ignition plug 50 is controlled by the ignition control device 60 based on the mixing ratio R of hydrogen gas. By controlling the presence or absence and timing of the ignition of each of the main ignition plugs 40 (40A, 40B) and the sub-ignition plug 50 based on the mixing ratio R of hydrogen gas, as will be described later, a decrease in thermal efficiency and an increase in NO x emission during combustion of the fuel gas can be suppressed.

[0028] Here, referring further to FIGS. 3 and 4, the ignition control of each of the main ignition plugs 40 (40A, 40B) and the sub-ignition plug 50 by the ignition control device 60 will be described. FIG. 3 is a diagram showing the ignition timing of the main ignition plug and the sub-ignition plug by the ignition control device according to one embodiment. FIG. 4 is a diagram showing the ignition timing of the main ignition plug and the sub-ignition plug by the ignition control device according to another embodiment.

[0029] FIGS. 3 and 4 are graphs showing an example of the relationship between the ignition timing θ (θ1, θ2) of the main ignition plug 40 (40A, 40B) or the sub-ignition plug 50 and the mixing ratio R of hydrogen gas. The ignition timing θ is drawn so that it advances as it goes upward on the graph and retards as it goes downward on the graph. Also, the solid line means ignition is performed, and the dashed line means ignition may or may not be performed.

[0030] In some embodiments, as shown in FIGS. 3 and 4, the ignition control device 60 is configured to ignite the sub-ignition plug 50 before the main ignition plug 40 (40A, 40B) or to ignite only the sub-ignition plug 50 when the mixing ratio R of hydrogen gas is less than the first threshold value R_th1. That is, when the ignition control device 60 ignites the main ignition plug 40 (40A, 40B) and the sub-ignition plug 50, the ignition control is performed such that the ignition timing θ2 of the sub-ignition plug 50 is advanced with respect to the ignition timing θ1 of the main ignition plug 40 (40A, 40B). Further, the ignition control device 60 is configured to ignite the main ignition plug 40 (40A, 40B) before the sub-ignition plug 50 or to ignite only the main ignition plug 40 (40A, 40B) when the mixing ratio R of hydrogen gas is greater than or equal to the first threshold value R_th1. That is, when the ignition control device 60 ignites the main ignition plug 40 (40A, 40B) and the sub-ignition plug 50, the ignition control is performed such that the ignition timing θ1 of the main ignition plug 40 (40A, 40B) is advanced with respect to the ignition timing θ2 of the sub-ignition plug 50.

[0031] The first threshold value R_th1 is set as the mixing ratio R of hydrogen gas when the combustion of the fuel gas begins to become steep due to an increase in the mixing ratio R of hydrogen gas. Further, according to the findings of the inventors, when the fuel of the fuel gas becomes steep due to an increase in the mixing ratio R of hydrogen gas, the decrease in thermal efficiency and the increase in NO x emission become significant. Therefore, the first threshold value R_th1 may be set as the mixing ratio R of hydrogen gas when the decrease in thermal efficiency or the increase in NO x emission begins to become significant when increasing the mixing ratio R of hydrogen gas. The first threshold value R_th1 is recorded in the memory 64 of the ignition control device 60 described above and is referred to in the processing of the processor 62.

[0032] According to the above configuration, when the mixing ratio R of hydrogen gas is equal to or higher than the first threshold value R_th1, the ignition control device 60 burns the fuel gas in the main combustion chamber MC by igniting the main ignition plugs 40 (40A, 40B). Therefore, compared with the case where the fuel gas in the main combustion chamber MC is burned by the flame caused by the ignition of the sub-ignition plug 50, the combustion of the combustion gas can be slowed down. Thereby, a decrease in thermal efficiency and an increase in NO x emission can be suppressed. Further, when the mixing ratio R of hydrogen gas is less than the first threshold value R_th1, the ignition control device 60 burns the fuel gas in the main combustion chamber MC by the flame caused by the ignition of the sub-ignition plug 50. Therefore, compared with the case where the fuel gas in the main combustion chamber MC is burned by the ignition of the main ignition plugs 40 (40A, 40B), a decrease in thermal efficiency during the combustion of the fuel gas can be suppressed. When the ignition control device 60 ignites the main ignition plugs 40 (40A, 40B) after the ignition of the sub-ignition plug 50, the unburned fuel gas in the main combustion chamber MC can be effectively burned.

[0033] In one embodiment, the gas engine 1 is configured not to supply fuel gas into the sub-combustion chamber PC when the mixing ratio R of hydrogen gas is equal to or higher than the first threshold value R_th1. In this case, as shown in FIGS. 3 and 4, the ignition control device 60 may be configured to ignite only the main ignition plugs 40 (40A, 40B), or may be configured to ignite the sub-ignition plug 50 after the main ignition plugs 40 (40A, 40B). That is, when the mixing ratio R of hydrogen gas is equal to or higher than the first threshold value R_th1, the ignition control device 60 may perform ignition control such that the ignition timing θ2 of the sub-ignition plug 50 is retarded with respect to the ignition timing θ1 of the main ignition plugs 40 (40A, 40B).

[0034] In the embodiments illustrated in FIGS. 3 and 4, when the sub-ignition plug 50 is ignited after the main ignition plug 40 (40A, 40B), the ignition timing θ2 of the sub-ignition plug 50 when the co-combustion rate R of hydrogen gas is equal to or higher than the first threshold value R_th1 may be controlled to be constant regardless of the co-combustion rate R of hydrogen gas. In other embodiments (not shown), the ignition timing θ2 of the sub-ignition plug 50 may be controlled to advance or retard as the co-combustion rate R of hydrogen gas increases. At that time, the ignition timing θ2 of the sub-ignition plug 50 may be controlled to advance or retard at a constant rate as the co-combustion rate R of hydrogen gas increases, or may be controlled such that the degree of advance or the degree of retard changes.

[0035] In the embodiments shown in FIGS. 3 and 4, the ignition control device 60 is configured to retard the ignition timing θ1 of the main ignition plug 40 (40A, 40B) as the co-combustion rate R of hydrogen gas increases when the co-combustion rate R of hydrogen gas is equal to or higher than the first threshold value R_th1. That is, the ignition timing θ1 of the main ignition plug 40 (40A, 40B) is controlled to be the most advanced when the co-combustion rate R of hydrogen gas is equal to the first threshold value R_th1, and to be the most retarded when the co-combustion rate R of hydrogen gas is 100%.

[0036] In the embodiments illustrated in FIGS. 3 and 4, the ignition timing θ1 of the main ignition plug 40 (40A, 40B) is controlled to retard at a constant rate as the co-combustion rate R of hydrogen gas increases. In other embodiments (not shown), the ignition timing θ1 of the main ignition plug 40 (40A, 40B) may be controlled such that the degree of retard changes as the co-combustion rate R of hydrogen gas increases.

[0037] In the embodiment shown in FIG. 4, the ignition control device 60 is configured to ignite the sub-ignition plug 50 before the main ignition plug 40 (40A, 40B) when the mixing ratio R of hydrogen gas is less than the first threshold value R_th1 and greater than or equal to the second threshold value R_th2. That is, the ignition control device 60 performs ignition control so that the ignition timing θ2 of the sub-ignition plug 50 is more advanced than the ignition timing θ1 of the main ignition plug 40 (40A, 40B) when the mixing ratio R of hydrogen gas is less than the first threshold value R_th1 and greater than or equal to the second threshold value R_th2. The second threshold value R_th2 is set as a mixing ratio R of hydrogen gas that is smaller than the first threshold value R_th1. Further, the second threshold value R_th2 is set as the mixing ratio R of hydrogen gas when knocking starts to occur in the main combustion chamber MC due to an increase in the mixing ratio R of hydrogen gas. Note that the second threshold value R_th2 is recorded in the memory 64 of the ignition control device 60 described above and is referred to in the processing of the processor 62.

[0038] In the embodiments shown in FIGS. 3 and 4, the ignition control device 60 is configured to discontinuously advance the ignition timing θ1 of the main ignition plug 40 (40A, 40B) at the first threshold value R_th1 when increasing the mixing ratio R of hydrogen gas from less than the first threshold value R_th1 to greater than or equal to the first threshold value R_th1. That is, the ignition control device 60 is configured to execute control such that the ignition timing θ1 of the main ignition plug 40 (40A, 40B) at the first threshold value R_th1 is more advanced than the ignition timing θ1 of the main ignition plug 40 (40A, 40B) when it is less than the first threshold value R_th1.

[0039] In the embodiment shown in FIG. 4, the ignition control device 60 is configured to ignite only the sub-ignition plug 50 when the mixing ratio R of hydrogen gas is less than the second threshold value R_th2.

[0040] In the embodiments shown in FIGS. 3 and 4, the ignition control device 60 is configured to retard the ignition timing θ2 of the sub-ignition plug 50 as the mixing ratio R of hydrogen gas increases when the mixing ratio R of hydrogen gas is less than the first threshold value R_th1. That is, the ignition timing θ2 of the sub-ignition plug 50 is controlled to be on the most advanced side when the mixing ratio R of hydrogen gas is 0%.

[0041] In the embodiments illustrated in FIGS. 3 and 4, the ignition timing θ2 of the sub-ignition plug 50 is controlled such that the degree of retardation increases as the mixing ratio R of hydrogen gas increases. In other embodiments not shown, the ignition timing θ2 of the sub-ignition plug 50 may be controlled to retard at a constant rate as the mixing ratio R of hydrogen gas increases.

[0042] Also, in the embodiments illustrated in FIGS. 3 and 4, the ignition timing θ2 of the sub-ignition plug 50 is controlled such that the difference from the ignition timing θ1 of the main ignition plugs 40 (40A, 40B) decreases as the mixing ratio R of hydrogen gas increases. That is, the difference between the ignition timing θ2 of the sub-ignition plug 50 and the ignition timing θ1 of the main ignition plugs 40 (40A, 40B) is controlled to be maximum when the mixing ratio R of hydrogen gas is 0% and minimum when the mixing ratio R of hydrogen gas approximates the first threshold value R_th1.

[0043] Here, referring to FIG. 5, a specific example of the ignition control of the main ignition plugs 40 (40A, 40B) or the sub-ignition plug 50 by the ignition control device 60 will be described. FIG. 5 is a flowchart showing the flow from intake to exhaust of a pre-chamber type gas engine according to an embodiment.

[0044] First, the case where the co - combustion rate R of hydrogen gas is less than the first threshold value R_th1 (Yes in step S10) will be described. When the co - combustion rate R is less than the first threshold value R_th1, the first air - fuel mixture A1 is supplied to the main combustion chamber MC of the gas engine 1 (step S20), and the second air - fuel mixture A2 is supplied to the auxiliary combustion chamber PC of the gas engine 1 (step S22). Note that the order of step S20 and step S22 is not particularly limited. Step S20 may be performed after step S22, or step S20 and step S22 may be performed substantially simultaneously.

[0045] After step S20 and step S22, the sub - ignition plug 50 is ignited by the ignition control device 60 (step S24). When the co - combustion rate R of hydrogen gas is less than the second threshold value R_th2 (Yes in step S26), the first air - fuel mixture A1 after combustion is exhausted from the main combustion chamber MC as exhaust A3 (step S40). On the other hand, when the co - combustion rate R of hydrogen gas is greater than or equal to the second threshold value R_th2 (No in step S26), after the sub - ignition plug 50 is ignited, the main ignition plugs 40 (40A, 40B) are ignited by the ignition control device 60 (step S28). After step S28, the first air - fuel mixture A1 after combustion is exhausted from the main combustion chamber MC as exhaust A3 (step S40).

[0046] Return to step S10, and the case where the co - combustion rate R of hydrogen gas is greater than or equal to the first threshold value R_th1 (No in step S10) will be described. When the co - combustion rate R of hydrogen gas is greater than or equal to the first threshold value R_th1, the first air - fuel mixture A1 is supplied to the main combustion chamber MC of the gas engine 1 (step S30). Note that the supply of the second air - fuel mixture A2 to the auxiliary combustion chamber PC of the gas engine 1 is not performed. After step S30, the main ignition plugs 40 (40A, 40B) are ignited by the ignition control device 60 (step S32).

[0047] After step S32, when there is residual gas as unburned fuel gas in the secondary combustion chamber PC (Yes in step S34), the sub-ignition plug 50 is ignited by the ignition control device 60 (step S36). The residual gas burned by the ignition of the sub-ignition plug 50 and the fuel gas burned by the ignition of the main ignition plugs 40 (40A, 40B) are discharged from the main combustion chamber MC as exhaust A3 (step S40). On the other hand, when there is no residual gas as unburned fuel gas in the secondary combustion chamber PC (Yes in step S34), without igniting the sub-ignition plug 50, the fuel gas burned by the ignition of the main ignition plugs 40 (40A, 40B) is discharged from the main combustion chamber MC as exhaust A3 (step S40).

[0048] Hereafter, with reference to FIGS. 1, 2, 6, and 7, the specific arrangement of the main ignition plugs 40 (40A, 40B) in the above-described auxiliary chamber type gas engine 1 (1A, 1B) will be described. FIG. 6 is a schematic diagram showing the arrangement of the ignition parts of the main ignition plugs in the main combustion chamber according to one embodiment. FIG. 7 is a schematic diagram showing the arrangement of the ignition parts of the main ignition plugs in the main combustion chamber according to another embodiment.

[0049] As described above with reference to FIGS. 1 and 2, the auxiliary chamber type gas engine 1 (1A, 1B) includes a cylinder liner 16, a piston 18, and a cylinder head 20 as the main combustion chamber forming part 10. And as shown in FIGS. 6 and 7, the central axis O1 of the cylinder liner 16 is defined as the 0% position X_0%, and the wall surface 16a of the cylinder liner 16 is defined as the 100% position X_100%.

[0050] In some embodiments, as shown in FIGS. 1 and 6, at least one main ignition plug 40 includes a central side main ignition plug 40A having an ignition part 44A arranged between the 0% position X_0% and the 20% position X_20%.

[0051] In the embodiments shown in FIGS. 1 and 6, the main ignition plug 40 includes one central main ignition plug 40A. In other embodiments (not shown), the main ignition plug 40 may include a plurality of central main ignition plugs 40A.

[0052] In some embodiments, as shown in FIGS. 2 and 7, at least one main ignition plug 40 includes an outer peripheral main ignition plug 40B having an ignition portion 44B disposed between the 60% position X_60% and the 100% position X_100%.

[0053] In the embodiments shown in FIGS. 2 and 7, the outer peripheral main ignition plugs 40B are respectively installed at different positions in the circumferential direction φ1 of the main combustion chamber MC.

[0054] In the embodiment illustrated in FIG. 7, the gas engine 1B includes four outer peripheral main ignition plugs 40B. In other embodiments (not shown), the number of the outer peripheral main ignition plugs 40B is not particularly limited. Note that the distances of each of the plurality of outer peripheral main ignition plugs 40B from the central axis O1 of the cylinder liner 16 may all be the same or may be different from each other.

[0055] In the embodiment shown in FIG. 7, at least one injection hole 32 includes a plurality of injection holes 32 respectively formed at different positions in the circumferential direction φ2 of the sub-combustion chamber forming portion 30. Further, each of the ignition portions 44B of the plurality of outer peripheral main ignition plugs 40B is respectively installed at a circumferential position between the adjacent injection holes 32 in the circumferential direction φ2 of the sub-combustion chamber forming portion 30 among the plurality of injection holes 32.

[0056] In the embodiment illustrated in FIG. 7, an ignition portion 44B of one outer peripheral main ignition plug 40B is installed between the adjacent injection holes 32 in the circumferential direction φ2 of the sub-combustion chamber forming portion 30. In other embodiments (not shown), ignition portions 44B of a plurality of outer peripheral main ignition plugs 40B may be installed between the adjacent injection holes 32 in the circumferential direction φ2 of the sub-combustion chamber forming portion 30.

[0057] Summarizing the characteristic configurations of the auxiliary chamber type gas engines 1 (1A, 1B) according to some of the above embodiments, it is as follows.

[0058] [1] The auxiliary chamber type gas engines (1; 1A, 1B) according to some embodiments are auxiliary chamber type gas engines (1; 1A, 1B) configured to be able to burn hydrocarbon gas and hydrogen gas as fuel gas, a main combustion chamber forming portion (10) that forms a main combustion chamber (MC), an auxiliary combustion chamber forming portion (30) that forms an auxiliary combustion chamber (PC) communicating with the main combustion chamber (10) via at least one injection hole (32), at least one main ignition plug (40; 40A, 40B) configured to ignite the fuel gas in the main combustion chamber (MC), at least one auxiliary ignition plug (50) configured to ignite the fuel gas in the auxiliary combustion chamber (PC), an ignition control device (60) configured to control the ignition of each of the main ignition plug (40; 40A, 40B) and the auxiliary ignition plug (50) based on the mixing ratio (R) of hydrogen gas, and are provided with.

[0059] According to the configuration of [1] above, the auxiliary chamber type gas engines (1; 1A, 1B) include a main ignition plug (40; 40A, 40B) configured to ignite the fuel gas in the main combustion chamber (MC) and an auxiliary ignition plug (50) configured to ignite the fuel gas in the auxiliary combustion chamber (PC). And the ignition of each of the main ignition plug (40; 40A, 40B) and the auxiliary ignition plug (50) is controlled by the ignition control device (60) based on the mixing ratio (R) of hydrogen gas. By controlling the presence or absence and timing of the ignition of each of the main ignition plug (40; 40A, 40B) and the auxiliary ignition plug (50) based on the mixing ratio (R) of hydrogen gas, as will be described later, a decrease in thermal efficiency and an increase in NO x emission during combustion of the fuel gas can also be suppressed.

[0060] For example, when the co - combustion rate (R) of hydrogen gas is high, by burning the fuel gas in the main combustion chamber (MC) by the ignition of the main ignition plugs (40; 40A, 40B), compared with the case of burning the fuel gas in the main combustion chamber (MC) by the flame ejected from the injection holes (32) formed in the sub - combustion chamber forming portion (30), the combustion of the combustion gas in the main combustion chamber (MC) can be slowed down. Thereby, a decrease in thermal efficiency and an increase in NO x emission can be suppressed. On the other hand, when the co - combustion rate (R) of hydrogen gas is low, if the fuel gas in the main combustion chamber (MC) is burned by the ignition of the main ignition plugs (40; 40A, 40B), the combustion of the combustion gas in the main combustion chamber (MC) becomes slow, and there is a possibility that the thermal efficiency during the combustion of the fuel gas decreases. Therefore, for example, when the co - combustion rate (R) of hydrogen gas is low, by burning the combustion gas in the main combustion chamber (MC) by the flame resulting from the ignition of the sub - ignition plug (50), a decrease in thermal efficiency during the combustion of the fuel gas can be suppressed.

[0061] [2] In some embodiments, in the configuration of [1] above, the ignition control device (60) is configured to cause the sub - ignition plug (50) to ignite earlier than the main ignition plugs (40; 40A, 40B), or to ignite only the sub - ignition plug (50), when the co - combustion rate (R) of hydrogen gas is less than the first threshold value (R_th1), and to cause the main ignition plugs (40; 40A, 40B) to ignite earlier than the sub - ignition plug (50), or to ignite only the main ignition plugs (40; 40A, 40B), when the co - combustion rate of hydrogen gas is equal to or greater than the first threshold value (R_th1).

[0062] According to the configuration of [2] above, when the co - combustion rate (R) of hydrogen gas is equal to or greater than the first threshold value (R_th1), the ignition control device (60) burns the fuel gas in the main combustion chamber (MC) by the ignition of the main ignition plugs (40; 40A, 40B). For this reason, compared with the case of burning the fuel gas in the main combustion chamber (MC) by the flame resulting from the ignition of the sub - ignition plug (50), the combustion of the combustion gas can be slowed down. Thereby, a decrease in thermal efficiency and an increase in NOx The increase in the discharge amount can be suppressed. Further, when the mixing ratio (R) of hydrogen gas is less than the first threshold value (R_th1), the ignition control device (60) burns the fuel gas in the main combustion chamber (MC) by the flame caused by the ignition of the sub-ignition plug (50). Therefore, compared with the case where the fuel gas in the main combustion chamber (MC) is burned by the ignition of the main ignition plug (40; 40A, 40B), it is possible to suppress a decrease in the thermal efficiency during the combustion of the fuel gas.

[0063] [3] In some embodiments, in the configuration of [2] above, the sub-chamber type gas engine (1; 1A, 1B) is configured not to supply fuel gas into the sub-combustion chamber (PC) when the mixing ratio (R) of hydrogen gas is equal to or greater than the first threshold value (R_th1). The ignition control device (60) is configured to ignite the sub-ignition plug (50) after the main ignition plug (40; 40A, 40B) when the mixing ratio (R) of hydrogen gas is equal to or greater than the first threshold value (R_th1).

[0064] As described in [2] above, when the mixing ratio (R) of hydrogen gas is equal to or greater than the first threshold value (R_th1), the fuel gas in the main combustion chamber (MC) is burned by the ignition of the main ignition plug (40; 40A, 40B). At this time, the fuel gas in the main combustion chamber (MC) flows from the main combustion chamber (MC) into the sub-combustion chamber (PC) through the injection holes (32) formed in the sub-combustion chamber forming portion (30). If the fuel gas that has flowed into the sub-combustion chamber (PC) remains without burning, knocking may occur in the sub-combustion chamber (PC). According to the configuration of [3] above, the fuel gas that has flowed into the sub-combustion chamber (PC) can be burned by the ignition of the sub-main ignition plug (50). Therefore, the possibility of knocking occurring in the sub-combustion chamber (PC) can be reduced.

[0065] [4] In some embodiments, in any of the configurations of [2] or [3] above, the ignition control device (60) When the mixing combustion ratio (R) of hydrogen gas is less than the first threshold value (R_th1) and is equal to or greater than the second threshold value (R_th2) smaller than the first threshold value (R_th1), the sub-ignition plug (50) is configured to be ignited before the main ignition plug (40; 40A, 40B).

[0066] As described in [2] above, when the mixing combustion ratio (R) of hydrogen gas is less than the first threshold value (R_th1), the fuel gas in the main combustion chamber (MC) is burned by the flame caused by the ignition of the sub-ignition plug (50). However, depending on the mixing combustion ratio (R) of hydrogen gas, unburned fuel gas may remain in the main combustion chamber (MC), and knocking may occur in the main combustion chamber (MC). According to the configuration of [4] above, the unburned gas in the main combustion chamber (MC) can be burned by the ignition of the main ignition plug (40; 40A, 40B). Therefore, the possibility of knocking occurring in the main combustion chamber (MC) can be reduced.

[0067] [5] In some embodiments, in the configuration of [4] above, the ignition control device (60) is configured such that when increasing the mixing combustion ratio (R) of hydrogen gas from less than the first threshold value (R_th1) to equal to or greater than the first threshold value (R_th1), the ignition timing (θ1) of the main ignition plug (40; 40A, 40B) is discontinuously advanced at the first threshold value (R_th1).

[0068] As described in [2] above, when the mixing combustion ratio (R) of hydrogen gas is equal to or greater than the first threshold value (R_th1), the combustion of the fuel gas becomes steep. For this reason, it is preferable to advance the ignition timing (θ1) of the main ignition plug (40; 40A, 40B). In this regard, according to the configuration of [5] above, compared with the case where the ignition timing (θ1) of the main ignition plug (40; 40A, 40B) is continuously advanced before and after the first threshold value (R_th1), the generation timing of the flame caused by the ignition of the main ignition plug (40; 40A, 40B) can be effectively advanced. Therefore, a decrease in thermal efficiency during combustion of the fuel gas and suppression of NO x emission can be more effectively realized.

[0069] [6] In some embodiments, in the configuration of the above [4] or [5], the ignition control device (60) is configured to ignite only the sub-ignition plug (50) when the co-combustion ratio (R) of hydrogen gas is less than the second threshold value (R_th2).

[0070] According to the configuration of the above [6], when the co-combustion ratio (R) of hydrogen gas is less than the second threshold value (R_th2), only the sub-ignition plug (50) is ignited, so that the ignition control by the ignition control device (60) can be simplified.

[0071] [7] In some embodiments, in any of the configurations of the above [2] to [6], the ignition control device (60) is configured to retard the ignition timing (θ1) of the main ignition plug (40; 40A, 40B) as the co-combustion ratio (R) of hydrogen gas increases when the co-combustion ratio (R) of hydrogen gas is equal to or higher than the first threshold value (R_th1).

[0072] Since the combustion speed of hydrogen gas is faster than that of hydrocarbon gas, the combustion speed of the fuel gas increases as the co-combustion ratio (R) of hydrogen gas increases. Therefore, when the co-combustion ratio (R) of hydrogen gas increases, the timing of combustion of the fuel gas may become excessively advanced with respect to the timing of expansion of the main combustion chamber (MC). In this regard, according to the configuration of the above [7], it is possible to suppress the ignition timing (θ1) of the main ignition plug (40; 40A, 40B) from becoming excessively advanced, so that a decrease in thermal efficiency and NO x emission can be more effectively suppressed during combustion of the fuel gas.

[0073] [8] In some embodiments, in any of the configurations of the above [2] to [7], the ignition control device (60) is configured to retard the ignition timing (θ2) of the sub-ignition plug (50) as the co-combustion ratio (R) of hydrogen gas increases when the co-combustion ratio (R) of hydrogen gas is less than the first threshold value (R_th1).

[0074] As described in [7] above, depending on the mixing combustion rate (R) of hydrogen gas, the timing of combustion of the fuel gas may be overly advanced. In this regard, according to the configuration of [8] above, since it is possible to suppress the ignition timing (θ2) of the sub-ignition plug (50) from being overly advanced, the decrease in thermal efficiency and NO x emission amount during the combustion of the fuel gas can be more effectively suppressed.

[0075] [9] In some embodiments, in any of the configurations of [1] to [8] above, The main combustion chamber forming portion (10) includes a cylinder liner (16), a piston (18) reciprocally disposed within the cylinder liner (16), and a cylinder head (20) that forms a main combustion chamber (MC) between the cylinder liner (16) and the piston (18). When the central axis (O1) of the cylinder liner (16) is defined as the 0% position (X_0%) and the wall surface (16a) of the cylinder liner (16) is defined as the 100% position (X_100%), At least one main ignition plug (40) includes a central main ignition plug (40A) having an ignition portion (44A) disposed between the 0% position (X_0%) and the 20% position (X_20%).

[0076] According to the configuration of [9] above, by igniting the central main ignition plug (40A) having the ignition portion (44A) disposed between the 0% position (X_0%) and the 20% position (X_20%), a hemispherical flame can be propagated from near the central axis (O1) of the cylinder liner (16). Therefore, the fuel gas in the main combustion chamber (MC) can be effectively burned.

[0077]

[10] In some embodiments, in any of the configurations of [1] to [9] above, The main combustion chamber forming portion (10) includes a cylinder liner (16), a piston (18) reciprocally disposed within the cylinder liner (16), and a cylinder head (20) that forms a main combustion chamber (MC) between the cylinder liner (16) and the piston (18). When the central axis line (O1) of the cylinder liner (16) is at the 0% position (X_0%) and the wall surface (16a) of the cylinder liner (16) is at the 100% position (X_100%), At least one main ignition plug (40) includes an outer peripheral side main ignition plug (40B) having an ignition part (44B) arranged between the 60% position (X_60%) and the 100% position (X_100%).

[0078] According to the configuration of

[10] above, by igniting the outer peripheral side main ignition plug (40B) having the ignition part (44B) arranged between the 60% position (X_60%) and the 100% position (X_100%), the unburned fuel gas remaining near the wall surface (16a) of the cylinder liner (16) can be effectively burned. Therefore, the occurrence of knocking in the main combustion chamber (MC) can be suppressed.

[0079]

[11] In some embodiments, in the configuration of

[10] above, The outer peripheral side main ignition plugs (40B) are respectively installed at different positions in the circumferential direction (φ1) of the main combustion chamber (MC).

[0080] According to the configuration of

[11] above, since the outer peripheral side main ignition plugs (40B) are respectively installed at different positions in the circumferential direction (φ1) of the main combustion chamber (MC), the unburned fuel gas remaining near the wall surface (16a) of the cylinder liner (16) can be burned more effectively. Therefore, the occurrence of knocking can be suppressed more effectively.

[0081]

[12] In some embodiments, in the configuration of

[11] above, At least one injection hole (32) includes a plurality of injection holes (32) respectively formed at different positions in the circumferential direction (φ2) of the sub-combustion chamber forming part (30), Each of the ignition parts (44B) of the plurality of outer peripheral side main ignition plugs (40B) is respectively installed at a circumferential position between the adjacent injection holes (32) in the circumferential direction (φ2) of the sub-combustion chamber forming part (30) among the plurality of injection holes (32).

[0082] According to the configuration of

[12] above, in the main combustion chamber (MC), the flame ejected from the plurality of injection holes (32) and the flame propagated from the ignition portion (44B) of the outer peripheral side main ignition plug (40B) are less likely to overlap. Since the flame can be effectively propagated in the main combustion chamber (MC), the occurrence of knocking can be more effectively suppressed.

[0083] As described above, some embodiments of the present invention have been described. However, it is natural that modifications may be made to the above-described embodiments without departing from the spirit of the present invention.

[0084] In this specification, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of being relatively displaced with tolerances, or at an angle or distance such that the same function can be obtained. For example, expressions indicating that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent a state in which there are tolerances or differences such that the same function can be obtained. Also, in this specification, expressions indicating shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. Also, in this specification, the expressions "comprising", "including", or "having" for one component are not exclusive expressions excluding the existence of other components.

Explanation of Reference Numerals

[0085] 1(1A, 1B): Sub-chamber type gas engine 10: Main combustion chamber forming portion 16: Cylinder liner 16a: Wall surface 18: Piston 20: Cylinder head 30: Sub-combustion chamber forming portion 32: Injection hole 40: Main ignition plug 40A: Central main ignition plug 40B: Outer peripheral main ignition plug 44(44A, 44B): Ignition section 50: Sub-ignition plug 54: Ignition section 60: Ignition control device MC: Main combustion chamber O1: Central axis PC: Sub-combustion chamber R: Mixing ratio R_th1: First threshold value R_th2: Second threshold value θ1, θ2: Ignition timing φ1, φ2: Circumferential direction

Claims

1. A pre-chamber gas engine configured to be capable of combusting hydrocarbon gas and hydrogen gas as fuel gas, A main combustion chamber forming portion that forms a main combustion chamber; an auxiliary combustion chamber forming portion that forms an auxiliary combustion chamber that is in communication with the main combustion chamber via at least one injection hole; at least one main spark plug configured to ignite the fuel gas in the main combustion chamber; at least one secondary spark plug configured to ignite the fuel gas in the secondary combustion chamber; an ignition control device configured to control ignition of each of the main ignition plug and the auxiliary ignition plug based on a mixed combustion ratio of the hydrogen gas; Equipped with Pre-chamber gas engine.

2. The ignition control device includes: When the mixed combustion ratio of the hydrogen gas is less than a first threshold value, the auxiliary spark plug is caused to ignite before the main ignition plug, or only the auxiliary spark plug is caused to ignite; 2. The gas engine according to claim 1, wherein the main ignition plug is caused to ignite before the auxiliary ignition plug, or only the main ignition plug is caused to ignite when the mixed combustion ratio of the hydrogen gas is equal to or greater than the first threshold value.

3. When the mixed combustion ratio of the hydrogen gas is equal to or greater than the first threshold value, the fuel gas is not supplied to the auxiliary combustion chamber, The ignition control device includes: When the mixed combustion ratio of the hydrogen gas is equal to or greater than the first threshold value, the auxiliary ignition plug is caused to ignite after the main ignition plug.

3. The pre-chamber gas engine according to claim 2.

4. The ignition control device includes: When the mixed combustion ratio of the hydrogen gas is less than the first threshold value and is equal to or greater than a second threshold value that is smaller than the first threshold value, the auxiliary ignition plug is configured to ignite before the main ignition plug.

4. The pre-chamber gas engine according to claim 2 or 3.

5. The ignition control device includes: when the mixed combustion ratio of the hydrogen gas is increased from less than the first threshold value to equal to or greater than the first threshold value, the ignition timing of the main ignition plug is discontinuously advanced at the first threshold value.

5. The pre-chamber gas engine according to claim 4.

6. The ignition control device includes: When the mixed combustion ratio of the hydrogen gas is less than the second threshold value, only the auxiliary ignition plug is ignited.

5. The pre-chamber gas engine according to claim 4.

7. The ignition control device includes: When the mixed combustion ratio of the hydrogen gas is equal to or greater than the first threshold value, the ignition timing of the main ignition plug is retarded as the mixed combustion ratio increases.

4. The pre-chamber gas engine according to claim 2 or 3.

8. The ignition control device includes: When the mixed combustion ratio of the hydrogen gas is less than the first threshold value, the ignition timing of the sub-ignition plug is retarded as the mixed combustion ratio increases.

4. The pre-chamber gas engine according to claim 2 or 3.

9. the main combustion chamber forming portion includes a cylinder liner, a piston reciprocally disposed within the cylinder liner, and a cylinder head that forms the main combustion chamber between the cylinder liner and the piston, When the central axis of the cylinder liner is set as the 0% position and the wall surface of the cylinder liner is set as the 100% position, The at least one main spark plug includes a center main spark plug having a spark portion disposed between a 0% position and a 20% position.

4. A pre-chamber gas engine according to claim 1 .

10. the main combustion chamber forming portion includes a cylinder liner, a piston reciprocally disposed within the cylinder liner, and a cylinder head that forms the main combustion chamber between the cylinder liner and the piston, When the central axis of the cylinder liner is set as the 0% position and the wall surface of the cylinder liner is set as the 100% position, The at least one main spark plug includes an outer periphery main spark plug having an ignition portion disposed between a 60% position and a 100% position.

4. A pre-chamber gas engine according to claim 1 .

11. The outer circumferential side main ignition plugs are installed at different positions in the circumferential direction of the main combustion chamber.

11. The pre-chamber gas engine according to claim 10.

12. the at least one injection hole includes a plurality of injection holes formed at different positions in a circumferential direction of the auxiliary combustion chamber forming portion, The ignition portions of the plurality of outer circumferential side main ignition plugs are respectively disposed at circumferential positions between adjacent nozzle holes in the auxiliary combustion chamber forming portion among the plurality of nozzle holes in the circumferential direction.

12. The pre-chamber gas engine according to claim 11.

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