Subchamber type gas engine

Abstract

A sub-chamber type gas engine according to the present invention has a main combustion chamber and a sub-chamber communicating with the main combustion chamber via a plurality of injection holes, and is provided with: a main combustion chamber forming unit that forms the main combustion chamber; a sub-chamber forming unit that forms a sub-chamber; the air inlet pipeline is used for guiding mixed gas containing gas fuel and air into the main combustion chamber; an ignition plug disposed in the sub-chamber and configured to ignite unburned fuel; and a mixed gas introduction line that branches off from the intake line and introduces the mixed gas flowing through the intake line into the sub-chamber as at least a portion of the unburned fuel.

Description

Technical Field

[0001] The present invention relates to a sub-chamber type gas engine.

[0002] This application claims priority based on Japanese Patent Application No. 2022-186118 filed with the Japan Patent Office on November 22, 2022, and incorporates its content herein. Background Art

[0003] Conventionally, a sub-chamber type gas engine is known, which includes a main combustion chamber defined between a piston and a cylinder head, and a sub-chamber (sub-combustion chamber) communicating with the main combustion chamber through a plurality of injection holes (for example, Patent Document 1). In the sub-chamber type gas engine, the mixed gas in the sub-chamber is ignited by a spark plug disposed in the sub-chamber, and the combustion flame generated by the ignition is ejected from each of the plurality of injection holes, thereby burning the lean premixed gas in the main combustion chamber.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-142222 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] In a sub-chamber type gas engine, there is an active sub-chamber that supplies gaseous fuel to the sub-chamber to increase the combustible concentration of the mixed gas around the spark plug. For this active sub-chamber, gaseous fuel cannot be supplied into the interior of the sub-chamber unless the gaseous fuel is pressurized to the same level as the pressurization pressure of the mixed gas. Therefore, the active sub-chamber requires a dedicated compressor to pressurize the gaseous fuel, which causes a problem of complicating the structure of the sub-chamber type gas engine.

[0009] In a sub-chamber type gas engine, there is a passive sub-chamber that does not receive fuel supply. This passive sub-chamber is affected by the exhaust gas remaining in the main combustion chamber or the sub-chamber in the previous cycle. By devising the shape of the injection holes or the sub-chamber in the passive sub-chamber, the combustible concentration of the mixed gas around the spark plug can be increased, but there is a problem of a large limitation on the shape of the injection holes or the sub-chamber.

[0010] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a sub-chamber type gas engine that can suppress the complication of the structure and increase the combustible concentration of the mixed gas near the spark plug in the sub-chamber.

[0011] Means for Solving the Technical Problem

[0012] At least one embodiment of the present invention relates to a pre-chamber type gas engine having a main combustion chamber and a pre-chamber communicating with the main combustion chamber via a plurality of injection holes. The pre-chamber type gas engine includes:

[0013] A main combustion chamber forming portion that forms the main combustion chamber;

[0014] A pre-chamber forming portion that forms the pre-chamber;

[0015] An intake pipe for introducing a mixture gas containing gaseous fuel and air into the main combustion chamber;

[0016] A spark plug disposed in the pre-chamber and configured to ignite unburned fuel; and

[0017] A mixture gas introduction pipe that branches from the intake pipe and is configured to introduce at least a part of the mixture gas flowing in the intake pipe as unburned fuel into the pre-chamber.

[0018] Advantages of the Invention

[0019] According to at least one embodiment of the present invention, there is provided a pre-chamber type gas engine capable of suppressing complication of the structure and increasing the combustible concentration of the mixture gas near the spark plug in the pre-chamber. Brief Description of the Drawings

[0020] Figure 1 FIG. schematically shows a pre-chamber type gas engine according to one embodiment of the present invention.

[0021] Figure 2 FIG. is a schematic cross-sectional view of a pre-chamber forming portion of a pre-chamber type gas engine according to one embodiment of the present invention.

[0022] Figure 3 FIG. is a schematic cross-sectional view of a pre-chamber forming portion of a pre-chamber type gas engine according to one embodiment of the present invention.

[0023] Figure 4 FIG. is a schematic view of a pre-chamber of a pre-chamber type gas engine according to one embodiment of the present invention as viewed from the main combustion chamber side in the extending direction of the central axis of the pre-chamber.

[0024] Figure 5 FIG. is a schematic cross-sectional view of a pre-chamber forming portion of a pre-chamber type gas engine according to one embodiment of the present invention.

[0025] Figure 6 FIG. schematically shows a pre-chamber type gas engine according to one embodiment of the present invention. Detailed Description of the Embodiment

[0026] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. Among them, regarding the dimensions, materials, shapes, relative arrangements, etc. of the constituent components described as embodiments or shown in the drawings, it is not intended to limit the scope of the present invention thereto, and it is only an illustrative example.

[0027] (Sub-chamber type gas engine)

[0028] Figure 1 and Figure 6 are diagrams schematically showing a sub-chamber type gas engine 1 according to an embodiment of the present invention. As Figure 1 and Figure 6 shown, the sub-chamber type gas engine 1 according to several embodiments has a main combustion chamber 20 of the engine 1 and a sub-chamber (sub-combustion chamber) 30 communicating with the main combustion chamber 20 via a plurality of injection holes 31. The sub-chamber type gas engine 1 of the present invention can be used for automotive, marine, or industrial use (for example, land power generation).

[0029] As Figure 1 and Figure 6 shown, the sub-chamber type gas engine 1 includes: a main combustion chamber forming portion 2 that forms the main combustion chamber 20; a sub-chamber forming portion 3 that forms the sub-chamber 30; an intake pipe 4 that introduces a mixed gas containing gaseous fuel and air into the main combustion chamber 20; a spark plug 5 disposed in the sub-chamber 30 and configured to ignite unburned fuel; and a mixed gas introduction pipe 6 that branches from the intake pipe 4 and introduces at least a part of the mixed gas flowing in the intake pipe 4 into the sub-chamber 30 as the unburned fuel.

[0030] As Figure 1 and Figure 6 shown, the sub-chamber type gas engine 1 includes: a cylinder 13 composed of a cylinder block 11 and a cylinder head member 12, in which a cylinder bore (cylindrical hole) 111 extending along the central axis CM of the main combustion chamber 20 is formed, and the cylinder head member 12 has a closing portion 121 that closes the open end of the cylinder bore 111; a piston 14 accommodated inside the cylinder bore 111 and capable of reciprocating in the extending direction of the axis of the cylinder bore 111 (the central axis CM of the main combustion chamber 20); and a sub-chamber cover 19.

[0031] (Main combustion chamber)

[0032] The above-mentioned main combustion chamber 20 is defined by the inner peripheral surface of the cylinder bore 111, the top surface of the piston 14, and the hole side surface 122 facing the top surface of the piston 14 in the closing portion 121 with a gap therebetween. The closing portion 121 and the hole side surface 122 of the closing portion 121 extend in the orthogonal direction with respect to the central axis CM of the main combustion chamber 20. The main combustion chamber forming portion 2 includes the portion of the cylinder block 11 in which the cylinder bore 111 is formed, the closing portion 121 of the cylinder head member 12, and the piston 14.

[0033] (Cylinder head component)

[0034] The cylinder head component 12 has the above-mentioned closing portion 121 and the spark plug support portion 123 that supports the spark plug 5. In the illustrated embodiment, the cylinder head component 12 includes a cylinder head 12A having the closing portion 121 and a sub-chamber plug holder 12B having the spark plug support portion 123. The cylinder head 12A and the sub-chamber plug holder 12B are separately formed, and the cylinder head 12A has a plug holder support portion 124 that supports the sub-chamber plug holder 12B. The sub-chamber plug holder 12B is installed inside the cylinder head 12A by being supported by the plug holder support portion 124. In addition, in several other embodiments, the cylinder head component 12 can be configured such that the cylinder head 12A and the sub-chamber plug holder 12B are integrated.

[0035] Figure 2 、 Figure 3 And Figure 5 are schematic cross-sectional views of the sub-chamber forming portion 3 of the sub-chamber type gas engine 1 according to an embodiment of the present invention. In Figure 2 、 Figure 3 And Figure 5 , a cross-section including the central axis CS along the central axis CS of the sub-chamber 30 of the sub-chamber forming portion 3 is shown. The sub-chamber plug holder 12B is disposed on the side opposite to the main combustion chamber 20 with respect to the closing portion 121 (the upper side in Figure 1 ), and the sub-chamber cover 19 is clamped between the sub-chamber plug holder 12B and the closing portion 121. The sub-chamber plug holder 12B has a plug hole 123A that extends along the axis CP of the spark plug 5. The spark plug 5 is accommodated inside the plug hole 123A. The spark plug 5 is fixedly supported by the sub-chamber plug holder 12B by screwing the thread portion formed on the outer surface of the spark plug 5 with the thread portion formed on the inner surface of the plug hole 123A. The spark plug support portion 123 includes the plug hole 123A having a thread portion formed on its inner surface.

[0036] (Spark plug)

[0037] As Figures 1 to 3 、 Figure 5 And Figure 6 shown, the spark plug 5 includes an ignition portion 51 (spark discharge portion) provided on one side (main combustion chamber 20 side) in the extending direction of the axis CP of the spark plug 5, and is a spark plug that ignites the mixed gas by generating a spark discharge in the ignition portion 51.

[0038] As Figure 2 、 Figure 3 And Figure 5As shown, the ignition unit 51 includes a center electrode 52 and a ground electrode 53. The ground electrode 53 is a ground electrode disposed non - contactingly on the center electrode 52, and a spark discharge gap for generating a spark is formed therebetween. The ignition unit 51 is disposed in the sub - chamber 30. In the illustrated embodiment, the ignition unit 51 is disposed at a position closer to the main combustion chamber 20 side (lower side in the figure) than the end face of the end portion 125 on the main combustion chamber 20 side of the sub - chamber plug holder 12B.

[0039] (Sub - chamber cover)

[0040] The sub - chamber cover 19 is formed in a bottomed cylindrical shape with the end portion on the main combustion chamber 20 side closed, and the end portion on the side away from the main combustion chamber 20 is serially connected to the end portion on the main combustion chamber 20 side of the sub - chamber plug holder 12B in a butted state. The sub - chamber cover 19 is inserted through a through - hole 126 extending along the central axis CM formed in the closing portion 121. The end portion 125 on the main combustion chamber 20 side of the sub - chamber cover 19 is provided to face the main combustion chamber 20.

[0041] (Sub - chamber)

[0042] As Figure 2 、 Figure 3 and Figure 5 shown, the sub - chamber 30 is defined by the inner surface of the sub - chamber cover 19 and the end face of the end portion 125 on the main combustion chamber 20 side of the sub - chamber plug holder 12B. The above - mentioned sub - chamber forming portion 3 includes the sub - chamber cover 19 and the end portion 125 on the main combustion chamber 20 side of the sub - chamber plug holder 12B. A plurality of injection holes 31 are formed at the end portion on the main combustion chamber 20 side of the sub - chamber cover 19. The plurality of injection holes 31 communicate the sub - chamber 30 formed inside the sub - chamber cover 19 with the outside. Through these plurality of injection holes 31, the main combustion chamber 20 and the sub - chamber 30 communicate with each other.

[0043] As Figure 1 and Figure 6 shown, intake holes 15 and exhaust holes 16 that communicate with the main combustion chamber 20 are formed around the sub - chamber cover 19 in the closing portion 121. The sub - chamber type gas engine 1 further includes an intake valve 17 capable of opening and closing the intake hole 15 and an exhaust valve 18 capable of opening and closing the exhaust hole 16. Hereinafter, a case where the sub - chamber type gas engine 1 is a four - stroke engine having a gas supply process of introducing a mixed gas (including air of combustion gas) into the main combustion chamber 20, a compression process of compressing the mixed gas in the main combustion chamber 20, a combustion process of burning the mixed gas ignited by the spark plug 5, and an exhaust process of discharging exhaust gas from the main combustion chamber 20 will be described. However, the sub - chamber type gas engine 1 of the present invention can also be applied to a two - stroke engine.

[0044] (Intake pipeline)

[0045] The intake pipe 4 has a flow path for a mixed gas containing gas fuel and air to flow. The above-mentioned intake hole 15 is formed at the downstream end of the intake pipe 4. In the illustrated embodiment, the auxiliary chamber type gas engine 1 further includes: a compressor 41, which is provided in the intake pipe 4 and is configured to compress the mixed gas flowing in the intake pipe 4; and a gas fuel supply pipe 7, which is connected to the intake pipe 4 at a position upstream of the compressor 41 and is used to supply gas fuel.

[0046] By driving the compressor 41, air is sucked from a position upstream of the connection portion of the intake pipe 4 with the gas fuel supply pipe 7. The intake pipe 4 can have an upstream end open, or can be connected to a supply source of gas (oxygen-rich gas) having an oxygen concentration higher than that of air in the atmosphere (for example, a gas tank storing oxygen-rich gas). The upstream end of the gas fuel supply pipe 7 is connected to a supply source of gas fuel (for example, a gas fuel tank storing gas fuel) 70. The pressure of the fuel gas flowing in the gas fuel supply pipe 7 is higher than the pressure of the mixed gas flowing in the intake pipe 4 upstream of the compressor 41. The gas fuel flowing into the intake pipe 4 through the gas fuel supply pipe 7 is mixed with the air flowing in the intake pipe 4, thereby forming a mixed gas.

[0047] In the illustrated embodiment, the secondary chamber type gas engine 1 further includes: an exhaust line 9 for discharging exhaust gas from the main combustion chamber 20; a turbine 43 provided in the exhaust line 9 and configured to be driven by the energy of the exhaust gas flowing in the exhaust line 9; and a rotating shaft 42 connecting the compressor 41 and the turbine 43. The secondary chamber type gas engine 1 includes a supercharger (turbocharger) composed of the compressor 41, the rotating shaft 42, and the turbine 43. The compressor 41 is connected to one end side of the rotating shaft 42, and the turbine 43 is connected to the other end side of the rotating shaft 42. The compressor 41 is coaxially connected to the turbine 43 via the rotating shaft 42, and thus rotates in conjunction with the rotation of the turbine 43 together with the rotating shaft 42. The compressor 41 is driven by the energy of the exhaust gas discharged from the main combustion chamber 20, and is configured to compress the mixed gas flowing in the intake line 4.

[0048] (Mixed gas introduction pipeline)

[0049] The upstream end of the mixed gas introduction pipeline 6 is connected to a position more downstream than the connection part of the intake pipeline 4 and the gas fuel supply pipeline 7. A mixed gas inlet 61 communicating with the sub-chamber 30 is formed at the downstream end of the mixed gas introduction pipeline 6. In the illustrated embodiment, the mixed gas inlet 61 is formed on the end face 125 of the end portion 12B of the sub-chamber plug holder on the main combustion chamber 20 side. As shown in the figure, the sub-chamber type gas engine 1 may further include a backflow prevention device (a check valve in the illustrated example) 90 provided in the mixed gas introduction pipeline 6 to prevent gas from flowing from the mixed gas inlet 61 toward the connection part P2 of the intake pipeline 4.

[0050] In the air supply process, the mixed gas introduced into the main combustion chamber 20 through the intake hole 15 is defined as the main combustion chamber side mixed gas. In the air supply process, the mixed gas introduced into the sub-chamber 30 through the mixed gas introduction pipeline 6 is defined as the sub-chamber side mixed gas. The main combustion chamber side mixed gas is mixed with the exhaust gas remaining in the main combustion chamber 20, so the combustible concentration is lower than that of the sub-chamber side mixed gas. The sub-chamber side mixed gas forms an over-rich mixed gas in the sub-chamber 30 by mixing with the gas in the sub-chamber 30. The mixed gas in the sub-chamber 30 is ignited and burned by the spark discharge in the ignition part 51 of the spark plug 5. Moreover, the ignited flame is ejected into the main combustion chamber 20 through a plurality of spray holes 31 to burn the lean premixed gas in the main combustion chamber 20.

[0051] As Figure 1 and Figure 6 shown, the sub-chamber type gas engine 1 according to several embodiments includes: the above-mentioned main combustion chamber forming part 2 that forms the main combustion chamber 20; the above-mentioned sub-chamber forming part 3 that forms the sub-chamber 30; the above-mentioned intake pipeline 4; the above-mentioned spark plug 5; and the above-mentioned mixed gas introduction pipeline 6.

[0052] According to the above structure, the sub-chamber type gas engine 1 can introduce the mixed gas flowing in the intake pipeline 4 into the sub-chamber 30 through the mixed gas introduction pipeline 6, and can increase the combustible concentration of the mixed gas near the spark plug 5 in the sub-chamber 30. Compared with the active sub-chamber, the above-mentioned sub-chamber type gas engine 1 does not require a dedicated compressor to boost the gas fuel fed into the sub-chamber 30 to the supercharging pressure level, so the complexity of its structure can be suppressed. And, compared with the passive sub-chamber, the influence of the residual exhaust gas in the previous cycle on the sub-chamber type gas engine 1 becomes smaller, so the design freedom of the shape of the plurality of spray holes 31 or the sub-chamber 30 is increased.

[0053] In several embodiments, as Figure 1 and Figure 6As shown, the above-described auxiliary chamber type gas engine 1 includes a compressor 41 provided in the intake pipe 4 and configured to compress the mixed gas. The connection portion P1 of the intake pipe 4 to the mixed gas introduction pipe 6 is provided at a position more downstream than the compressor 41. According to the above structure, the mixed gas boosted by the compressor 41 can be introduced into the auxiliary chamber 30 via the mixed gas introduction pipe 6. In this case, even without a dedicated compressor, the supply pressure of the mixed gas introduced into the auxiliary chamber 30 via the mixed gas introduction pipe 6 can be increased, so that the mixed gas can be effectively supplied to the auxiliary chamber 30.

[0054] As Figure 2 , Figure 3 and Figure 5 shown, in the auxiliary chamber type gas engine 1 according to several embodiments, each of the plurality of injection holes 31 is formed at an end portion 32 on the main combustion chamber 20 side in the extending direction of the central axis CS of the auxiliary chamber 30 in the auxiliary chamber forming portion 3. The spark plug 5 is installed at an end portion 33 on the side away from the main combustion chamber 20 in the extending direction of the central axis CS of the auxiliary chamber 30 in the auxiliary chamber forming portion 3. The mixed gas inlet 61 communicating with the auxiliary chamber 30 formed in the mixed gas introduction pipe 6 is formed at an end portion 33 on the side away from the main combustion chamber 20 of the auxiliary chamber 30 in the auxiliary chamber forming portion 3.

[0055] According to the above structure, since the spark plug 5 and the mixed gas inlet 61 are located on the same side (the side away from the main combustion chamber 20) in the extending direction of the central axis CS of the auxiliary chamber 30, the combustible concentration of the mixed gas near the spark plug 5 can be rapidly increased by the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61. And, since the temperature of the spark plug can be reduced by the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 in the gas supply process, damage to the spark plug 5 due to heat can be suppressed.

[0056] As Figure 2 , Figure 3 and Figure 5 shown, in the auxiliary chamber type gas engine 1 according to several embodiments, the above-described auxiliary chamber 30 includes: a first region 30A in which the ignition portion 51 of the spark plug 5 is disposed and the mixed gas inlet 61 is formed; a second region 30B in which a plurality of injection holes 31 are formed; and a third region 30C formed between the first region 30A and the second region 30B and having an area orthogonal to the central axis CS of the auxiliary chamber 30 smaller than that of the first region 30A.

[0057] The first region 30A is located on a side farther from the main combustion chamber 20 than the third region 30C, and the second region 30B is located on a position closer to the main combustion chamber 20 side than the third region 30C. In the illustrated embodiment, the first region 30A is located on a side farther from the main combustion chamber 20 than a portion of the sub-chamber cover 19 (sub-chamber forming portion 3) inserted through the through-hole 126. At least a part of the first region 30A includes an area reduction portion, and the area reduction portion has a smaller area orthogonal to the central axis CS of the sub-chamber 30 as it extends toward the main combustion chamber 20 side in the extending direction of the central axis CS of the sub-chamber 30, and the end on the main combustion chamber 20 side where the area orthogonal to the central axis CS of the sub-chamber 30 becomes the smallest is connected to the third region 30C. As shown in the figure, the third region 30C can extend from the connection portion with the first region 30A to the connection portion with the second region 30B, and the area orthogonal to the central axis CS of the sub-chamber 30 can be constant.

[0058] According to the above structure, the area of the third region 30C in the sub-chamber 30 orthogonal to the central axis CS of the sub-chamber 30 is smaller than that of the first region 30A. Therefore, the mixed gas introduced into the first region 30A from the mixed gas inlet 61 can be retained in the first region 30A where the ignition portion 51 of the spark plug 5 is located. Thus, the combustible concentration of the mixed gas near the spark plug 5 can be effectively increased, and the cooling effect of the mixed gas introduced into the sub-chamber 30 from the mixed gas inlet 61 on the spark plug 5 can be improved.

[0059] As Figure 2 and Figure 5 shown, in the sub-chamber type gas engine 1 according to several embodiments, in a cross-section along the central axis CS of the sub-chamber 30, the axis CP of the above-described spark plug 5 extends in the extending direction of the central axis CS of the sub-chamber 30. In this case, the installation of the spark plug 5 becomes easier compared to the case where the axis CP of the spark plug 5 is inclined with respect to the extending direction of the central axis CS of the sub-chamber 30.

[0060] As Figure 3 shown, in the sub-chamber type gas engine 1 according to several embodiments, in a cross-section along the central axis CS of the sub-chamber 30, the above-described spark plug 5 is inclined such that the distance of the axis CP of the spark plug 5 from the central axis CS of the sub-chamber 30 becomes shorter as it extends toward the main combustion chamber 20 side. In this case, it is easier to configure the mixed gas introduced into the sub-chamber 30 from the mixed gas inlet 61 to be directed toward the ignition portion 51 of the spark plug 5 compared to the case where the axis CP of the spark plug 5 extends in the extending direction of the central axis CS of the sub-chamber 30.

[0061] As Figure 2 , Figure 3 and Figure 5As shown, in a cross-section of the auxiliary chamber type gas engine 1 according to several embodiments along the central axis CS of the auxiliary chamber 30, at least a part of the mixed gas introduction pipe 6 including the mixed gas inlet 61, i.e., the inclined portion 60, is inclined such that the distance (the shortest distance) from the axis CP of the spark plug 5 becomes shorter as it approaches the mixed gas inlet 61 side.

[0062] According to the above structure, by inclining at least a part (the inclined portion 60) of the mixed gas introduction pipe 6 including the mixed gas inlet 61 toward the axis CP of the spark plug 5, the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 can be introduced near the spark plug 5. Thereby, the combustible concentration of the mixed gas near the spark plug 5 can be effectively increased, and the cooling effect of the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 on the spark plug 5 can be improved.

[0063] Figure 4 It is a schematic view of the auxiliary chamber 30 of the auxiliary chamber type gas engine 1 according to one embodiment of the present invention as viewed from the main combustion chamber 20 side in the extending direction of the central axis CS of the auxiliary chamber 30. As Figure 4 shown, when the auxiliary chamber type gas engine 1 according to several embodiments is viewed from one side in the extending direction of the central axis CS of the auxiliary chamber 30, at least a part (the inclined portion 60) of the mixed gas introduction pipe 6 including the mixed gas inlet 61 extends toward the ignition portion 51 of the spark plug 5.

[0064] In the illustrated embodiment, when viewed from one side in the extending direction of the central axis CS of the auxiliary chamber 30, the ignition portion 51 of the spark plug 5 is located on the imaginary straight line EL passing through the center (the center of the figure) of the mixed gas inlet 61. The imaginary straight line EL can be a straight line orthogonal to the imaginary plane including the mixed gas inlet 61, or a straight line extending the axis of the inclined portion 60.

[0065] According to the above structure, when viewed from one side in the extending direction of the central axis CS of the auxiliary chamber 30, by making at least a part of the mixed gas introduction pipe 6 including the mixed gas inlet 61 extend toward the ignition portion 51 of the spark plug 5, the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 can be introduced near the ignition portion 51. Thereby, the combustible concentration of the mixed gas near the ignition portion 51 can be effectively increased, and the cooling effect of the ignition portion 51 generated by the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 can be improved.

[0066] As Figure 5As shown, in the auxiliary chamber type gas engine 1 according to several embodiments, in a cross-section along the central axis CS of the auxiliary chamber 30, the ignition portion 51 of the ignition plug 5 is located on an imaginary straight line EL passing through the center (center of the circle) of the air-fuel mixture inlet 61. The imaginary straight line EL may be a straight line orthogonal to an imaginary plane including the air-fuel mixture inlet 61, or may be a straight line extending the axis of the inclined portion 60.

[0067] According to the above structure, the air-fuel mixture introduced into the auxiliary chamber 30 from the air-fuel mixture inlet 61 can be introduced into the ignition portion 51 of the ignition plug 5. Thereby, the combustible concentration of the air-fuel mixture near the ignition portion 51 can be effectively increased, and the cooling effect of the ignition portion 51 generated by the air-fuel mixture introduced into the auxiliary chamber 30 from the air-fuel mixture inlet 61 can be improved.

[0068] (Gas fuel inlet pipeline)

[0069] As Figure 6 shown, the auxiliary chamber type gas engine 1 according to several embodiments further includes: a gas fuel inlet pipeline 8, branched from the above gas fuel supply pipeline 7, and used to introduce at least a part of the gas fuel flowing in the gas fuel supply pipeline 7 as unburned fuel into the auxiliary chamber 30.

[0070] In the illustrated embodiment, the downstream end of the gas fuel inlet pipeline 8 is connected to the air-fuel mixture inlet pipeline 6, but a gas fuel inlet communicating with the auxiliary chamber 30 may be formed at the downstream end of the gas fuel inlet pipeline 8. The gas fuel inlet may be formed on the end face 125 of the end portion 12B of the auxiliary chamber plug holder 12B on the main combustion chamber 20 side.

[0071] When the auxiliary chamber type gas engine 1 is operated at a low load or no load at a specified ratio (for example, 30%) or less relative to the rated output, the supply pressure of the air-fuel mixture introduced into the auxiliary chamber 30 via the air-fuel mixture inlet pipeline 6 becomes low, and the combustion of the auxiliary chamber type gas engine 1 may become unstable. During low-load operation or no-load operation of the auxiliary chamber type gas engine 1, since the supply pressure of the gas fuel required to supply the gas fuel to the auxiliary chamber 30 is low, the gas fuel can be introduced into the auxiliary chamber 30 via the gas fuel inlet pipeline 8 even without providing a compressor for boosting the gas fuel to the gas fuel supply pipeline 7 or the gas fuel inlet pipeline 8. By mixing the gas fuel introduced into the auxiliary chamber 30 via the gas fuel inlet pipeline 8 with the gas in the auxiliary chamber 30, an overly rich air-fuel mixture can be formed in the auxiliary chamber 30.

[0072] According to the above structure, when the auxiliary chamber type gas engine 1 operates at a low load or no load below a specified ratio (e.g., 30%) relative to the rated output, the supply pressure of the mixed gas introduced into the auxiliary chamber 30 via the mixed gas introduction pipe 6 becomes low, and the combustion of the auxiliary chamber type gas engine 1 may become unstable. By introducing gas fuel into the auxiliary chamber 30 via the gas fuel introduction pipe 8 during low load operation or no load operation of the auxiliary chamber type gas engine 1, it is possible to suppress the combustion of the auxiliary chamber type gas engine 1 from becoming unstable.

[0073] (First backflow prevention device, second backflow prevention device)

[0074] As Figure 6 shown, the auxiliary chamber type gas engine 1 according to several embodiments further includes a first backflow prevention device (a check valve in the illustrated example) 91 and a second backflow prevention device (a check valve in the illustrated example) 92. The gas fuel introduction pipe 8 is connected to the mixed gas introduction pipe 6. The first backflow prevention device 91 is provided between the connection portion P2 of the mixed gas introduction pipe 6 to the intake pipe 4 and the connection portion P3 to the gas fuel introduction pipe 8, and is configured to prevent gas from flowing from the connection portion P3 to the gas fuel introduction pipe 8 toward the connection portion P2 to the intake pipe 4. The second backflow prevention device 92 is provided in the gas fuel introduction pipe 8, and is configured to prevent gas from flowing from the connection portion P4 to the mixed gas introduction pipe 6 toward the connection portion P5 to the gas fuel supply pipe 7.

[0075] As Figure 6 shown, the above-mentioned backflow prevention device 90 can be provided between the connection portion P3 of the mixed gas introduction pipe 6 to the gas fuel introduction pipe 8 and the mixed gas inlet 61.

[0076] During low load operation or no load operation of the auxiliary chamber type gas engine 1, the pressure of the gas fuel flowing in the gas fuel supply pipe 7 becomes higher than the pressure of the mixed gas flowing on the downstream side of the compressor 41 in the intake pipe 4. In this case, it is possible to supply gas fuel to the auxiliary chamber 30 via the gas fuel introduction pipe 8 and on the downstream side of the connection portion P3 of the mixed gas introduction pipe 6 to the gas fuel introduction pipe 8.

[0077] During high load operation of the auxiliary chamber type gas engine 1, the pressure of the mixed gas flowing on the downstream side of the compressor 41 in the intake pipe 4 becomes higher than the pressure of the gas fuel flowing in the gas fuel supply pipe 7. In this case, it is possible to supply the mixed gas to the auxiliary chamber 30 via the mixed gas introduction pipe 6.

[0078] According to the above structure, the auxiliary chamber type gas engine 1 can suppress the introduction of gaseous fuel into the intake pipe 4 via the air-fuel mixture introduction pipe 6 by providing the first backflow prevention device 91. Further, the auxiliary chamber type gas engine 1 can suppress the introduction of the air-fuel mixture into the gaseous fuel supply pipe 7 via the gaseous fuel introduction pipe 8 by providing the second backflow prevention device 92. According to the above structure, gaseous fuel can be supplied to the auxiliary chamber 30 during low load operation or no load operation of the auxiliary chamber type gas engine 1, and an air-fuel mixture can be supplied to the auxiliary chamber 30 via the air-fuel mixture introduction pipe 6 during high load operation of the auxiliary chamber type gas engine 1.

[0079] In this specification, expressions indicating relative or absolute arrangement such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only represent such an arrangement in a strict sense, but also represent a state of relative displacement in terms of an angle or distance within a tolerance or to an extent that can achieve the same function.

[0080] For example, expressions indicating a situation where things are in the same state such as "identical", "equal", and "homogeneous" not only represent the same state in a strict sense, but also represent a state with a difference within a tolerance or to an extent that can achieve the same function.

[0081] Further, in this specification, expressions indicating a shape such as a quadrilateral or a cylindrical shape not only represent a shape such as a quadrilateral or a cylindrical shape in a strictly geometric sense, but also represent a shape including concavo-convex portions or chamfered portions within a range where the same effect can be obtained.

[0082] Further, in this specification, an expression such as "comprising", "including", or "having" a component does not represent an exclusive expression excluding the existence of other components.

[0083] The present invention is not limited to the above-described embodiments, and also includes modified forms of the above-described embodiments or forms obtained by appropriately combining these forms.

[0084] The content described in the above several embodiments can be understood as follows.

[0085] 1) The auxiliary chamber type gas engine 1 according to at least one embodiment of the present invention includes a main combustion chamber 20 and an auxiliary chamber 30 communicating with the main combustion chamber 20 via a plurality of injection holes 31, and the auxiliary chamber type gas engine 1 includes:

[0086] A main combustion chamber forming portion 2 that forms the main combustion chamber 20;

[0087] An auxiliary chamber forming portion 3 that forms the auxiliary chamber 30;

[0088] An intake pipe 4 for introducing a mixed gas containing gaseous fuel and air into the main combustion chamber 20;

[0089] A spark plug 5 disposed in the sub-chamber 30 and configured to ignite unburned fuel; and

[0090] A mixed gas introduction pipe 6 branching from the intake pipe 4 and configured to introduce at least a part of the mixed gas flowing in the intake pipe 4 as the unburned fuel into the sub-chamber 30.

[0091] According to the structure of 1) above, the sub-chamber type gas engine 1 can introduce the mixed gas flowing in the intake pipe 4 into the sub-chamber 30 via the mixed gas introduction pipe 6, and can increase the combustible concentration of the mixed gas near the spark plug 5 in the sub-chamber 30. Compared with the active sub-chamber, the sub-chamber type gas engine 1 does not require a dedicated compressor to boost the gaseous fuel fed into the sub-chamber 30 to the supercharging pressure level, and thus can suppress the complication of its structure. Compared with the passive sub-chamber, the influence of the residual exhaust gas in the previous cycle on the sub-chamber type gas engine 1 becomes smaller, and thus the degree of freedom in designing the shape of multiple injection holes or the sub-chamber is increased.

[0092] 2) In several embodiments, for the sub-chamber type gas engine 1 described in 1) above, wherein,

[0093] The multiple injection holes 31 are respectively formed at the end 32 on the main combustion chamber 20 side in the extending direction of the central axis (gaseous fuel supply pipe 7) of the sub-chamber 30,

[0094] The spark plug 5 is installed at the end 33 on the side away from the main combustion chamber 20 in the extending direction of the central axis CS of the sub-chamber 30,

[0095] A mixed gas inlet 61 communicating with the sub-chamber 30 formed in the mixed gas introduction pipe 6 is formed at the end 33 on the side away from the main combustion chamber 20 of the sub-chamber 30.

[0096] According to the structure of 2) above, since the spark plug 5 and the mixed gas inlet 61 are located on the same side (the side away from the main combustion chamber 20) in the extending direction of the central axis CS of the sub-chamber 30, the combustible concentration of the mixed gas near the spark plug 5 can be rapidly increased by the mixed gas introduced into the sub-chamber 30 from the mixed gas inlet 61. And, since the temperature of the spark plug can be reduced by the mixed gas introduced into the sub-chamber 30 from the mixed gas inlet 61 during the gas supply process, the thermal damage of the spark plug 5 can be suppressed.

[0097] 3) In several embodiments, for the sub-chamber type gas engine 1 described in 2) above, wherein the sub-chamber 30 includes:

[0098] The first region 30A is provided with the ignition part 51 of the spark plug 5 and formed with the mixture gas inlet 61;

[0099] The second region 30B is formed with the plurality of injection holes 31; and

[0100] The third region 30C is formed between the first region 30A and the second region 30B, and the area orthogonal to the central axis CS of the sub-chamber 30 is smaller than that of the first region 30A.

[0101] According to the structure of the above 3), in the sub-chamber 30, the area orthogonal to the central axis CS of the third region 30C is smaller than that of the first region 30A. Therefore, the mixture gas introduced from the mixture gas inlet 61 into the first region 30A can be retained in the first region 30A where the ignition part 51 of the spark plug 5 exists. Thereby, the combustible concentration of the mixture gas near the spark plug 5 can be effectively increased, and the cooling effect of the mixture gas introduced from the mixture gas inlet 61 into the sub-chamber 30 on the spark plug 5 can be improved.

[0102] 4) In several embodiments, for the sub-chamber type gas engine 1 according to the above 3), wherein, in a cross-section along the central axis CS of the sub-chamber 30, the axis CP of the spark plug 5 extends along the extending direction of the central axis CS of the sub-chamber 30.

[0103] According to the structure of the above 4), the axis CP of the spark plug 5 extends along the extending direction of the central axis CS of the sub-chamber 30. In this case, compared with the case where the axis CP of the spark plug 5 is inclined with respect to the extending direction of the central axis CS of the sub-chamber 30, the installation of the spark plug 5 becomes easier.

[0104] 5) In several embodiments, for the sub-chamber type gas engine 1 according to the above 3),

[0105] In a cross-section along the central axis CS of the sub-chamber 30, the spark plug 5 is inclined such that the axis CP of the spark plug 5 becomes shorter in distance from the central axis CS of the sub-chamber 30 as it faces the main combustion chamber 20 side.

[0106] According to the structure of the above 5), the axis CP of the spark plug 5 is inclined with respect to the extending direction of the central axis CS of the sub-chamber 30. In this case, compared with the case where the axis CP of the spark plug 5 extends along the extending direction of the central axis CS of the sub-chamber 30, it is easier to configure the mixture gas introduced from the mixture gas inlet 61 into the sub-chamber 30 to face the ignition part 51 of the spark plug 5.

[0107] 6) In several embodiments, for the auxiliary chamber type gas engine 1 according to any one of the above 2) to the above 5), wherein, in a cross-section along the central axis CS of the auxiliary chamber 30, at least a part of the mixed gas introduction pipe 6 including the mixed gas inlet 61 is inclined in such a manner that the distance from the axis CP of the spark plug 5 becomes shorter as it approaches the side of the mixed gas inlet 61.

[0108] According to the structure of the above 6), by inclining at least a part of the mixed gas introduction pipe 6 including the mixed gas inlet 61 toward the axis CP of the spark plug 5, the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 can be introduced near the spark plug 5. Thereby, the combustible concentration of the mixed gas near the spark plug 5 can be effectively increased, and the cooling effect of the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 on the spark plug 5 can be improved.

[0109] 7) In several embodiments, for the auxiliary chamber type gas engine 1 according to any one of the above 2) to the above 6), wherein, when viewed from one side in the extending direction of the central axis CS of the auxiliary chamber 30, at least a part of the mixed gas introduction pipe 6 including the mixed gas inlet 61 extends toward the ignition part 51 of the spark plug 5.

[0110] According to the structure of the above 7), when viewed from one side in the extending direction of the central axis CS of the auxiliary chamber 30, by making at least a part of the mixed gas introduction pipe 6 including the mixed gas inlet 61 extend toward the ignition part 51 of the spark plug 5, the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 can be introduced near the ignition part 51. Thereby, the combustible concentration of the mixed gas near the ignition part 51 can be effectively increased, and the cooling effect of the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 on the ignition part 51 can be improved.

[0111] 8) In several embodiments, for the auxiliary chamber type gas engine 1 according to any one of the above 2) to the above 7), wherein,

[0112] In a cross-section along the central axis CS of the auxiliary chamber 30, the ignition part 51 of the spark plug 5 is located on an imaginary straight line EL passing through the center of the mixed gas inlet 61.

[0113] According to the structure of the above 8), the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 can be introduced into the ignition part 51 of the spark plug 5. Thereby, the combustible concentration of the mixed gas near the ignition part 51 can be effectively increased, and the cooling effect of the mixed gas introduced into the auxiliary chamber 30 from the mixed gas inlet 61 on the ignition part 51 can be improved.

[0114] 9) In several embodiments, the auxiliary chamber type gas engine 1 according to any one of the above 1) to 8) further includes

[0115] a compressor 41 disposed in the intake pipe 4 and configured to compress the mixed gas,

[0116] and a connection portion (P1) of the intake pipe 4 and the mixed gas introduction pipe 6 is disposed at a position more downstream than the compressor 41.

[0117] According to the structure of the above 9), the mixed gas boosted by the compressor 41 can be introduced into the auxiliary chamber 30 via the mixed gas introduction pipe 6. In this case, even without a dedicated compressor, the supply pressure of the mixed gas introduced into the auxiliary chamber 30 via the mixed gas introduction pipe 6 can be increased, so that the mixed gas can be effectively supplied to the auxiliary chamber 30.

[0118] 10) In several embodiments, the auxiliary chamber type gas engine 1 according to the above 9) further includes:

[0119] a gas fuel supply pipe 7 connected to a position of the intake pipe 4 more upstream than the compressor 41 and configured to supply the gas fuel; and

[0120] a gas fuel introduction pipe 8 branched from the gas fuel supply pipe 7 and configured to introduce at least a part of the gas fuel flowing in the gas fuel supply pipe 7 into the auxiliary chamber 30 as the unburned fuel.

[0121] According to the structure of the above 10), when the auxiliary chamber type gas engine 1 is operated at a low load or no load at a rate below a specified ratio with respect to the rated output, the supply pressure of the mixed gas introduced into the auxiliary chamber 30 via the mixed gas introduction pipe 6 becomes low, and the combustion of the auxiliary chamber type gas engine 1 may become unstable. By introducing gas fuel into the auxiliary chamber 30 via the gas fuel introduction pipe 8 during low load operation or no load operation of the auxiliary chamber type gas engine 1, the combustion of the auxiliary chamber type gas engine 1 becoming unstable can be suppressed.

[0122] 11) In several embodiments, for the auxiliary chamber type gas engine 1 described in 10) above, the gas fuel introduction pipe 8 is connected to the mixed gas introduction pipe 6, and the auxiliary chamber type gas engine 1 further includes: a first backflow prevention device 91 disposed between the connection portion (P2) of the mixed gas introduction pipe 6 to the intake pipe 4 and the connection portion (P3) of the mixed gas introduction pipe 6 to the gas fuel introduction pipe 8, and preventing gas from flowing from the connection portion (P3) of the gas fuel introduction pipe 8 toward the connection portion (P2) of the intake pipe 4; and a second backflow prevention device 92 disposed in the gas fuel introduction pipe 8, and preventing gas from flowing from the connection portion (P4) of the gas fuel introduction pipe 8 toward the connection portion (P5) of the gas fuel supply pipe 7.

[0123] According to the structure of 11) above, the auxiliary chamber type gas engine 1 can suppress the introduction of gas fuel into the intake pipe 4 via the mixed gas introduction pipe 6 by providing the first backflow prevention device 91. Also, the auxiliary chamber type gas engine 1 can suppress the introduction of the mixed gas into the gas fuel supply pipe 7 via the gas fuel introduction pipe 8 by providing the second backflow prevention device 92. According to the structure of 11) above, during low-load operation or no-load operation of the auxiliary chamber type gas engine 1, gas fuel can be supplied to the auxiliary chamber 30, and during high-load operation of the auxiliary chamber type gas engine 1, the mixed gas can be supplied to the auxiliary chamber 30 via the mixed gas introduction pipe 6.

[0124] Symbolic Explanation

[0125] 1 - Auxiliary chamber type gas engine, 2 - Main combustion chamber forming portion, 3 - Auxiliary chamber forming portion, 4 - Intake pipe, 5 - Spark plug, 6 - Mixed gas introduction pipe, 7 - Gas fuel supply pipe, 8 - Gas fuel introduction pipe, 9 - Exhaust pipe, 11 - Cylinder block, 12 - Cylinder head component, 12A - Cylinder head, 12B - Auxiliary chamber plug holder, 13 - Cylinder, 14 - Piston, 15 - Intake hole, 16 - Exhaust hole, 17 - Intake valve, 18 - Exhaust valve, 19 - Auxiliary chamber cover, 20 - Main combustion chamber, 30 - Auxiliary chamber, 31 - Injection hole, 41 - Compressor, 42 - Rotating shaft, 43 - Turbine, 51 - Ignition portion, 61 - Mixed gas inlet, 90 - Backflow prevention device, 91 - First backflow prevention device, 92 - Second backflow prevention device, 111 - Cylinder bore, 121 - Closed portion, 122 - Hole side surface, 123 - Spark plug support portion, 124 - Plug holder support portion, 125 - End portion, 126 - Through hole, CP - Axis of the spark plug, CS - Central axis of the auxiliary chamber, EL - Imaginary straight line.

Claims

1. A sub-chamber type gas engine having a main combustion chamber and a sub-chamber communicating with the main combustion chamber via a plurality of injection holes, the sub-chamber type gas engine comprising: A main combustion chamber forming portion that forms the main combustion chamber; A sub-chamber forming portion that forms the sub-chamber; An intake pipe for introducing a mixed gas containing gaseous fuel and air into the main combustion chamber; A spark plug disposed in the sub-chamber and configured to ignite unburned fuel; And A mixed gas introduction pipe that branches from the intake pipe and is configured to introduce at least a part of the mixed gas flowing in the intake pipe as the unburned fuel into the sub-chamber.

2. The sub-chamber type gas engine according to claim 1, Wherein, The plurality of injection holes are respectively formed at an end portion on the main combustion chamber side in the extending direction of the central axis of the sub-chamber, The spark plug is installed at an end portion on a side away from the main combustion chamber in the extending direction of the central axis of the sub-chamber, A mixed gas inlet port that communicates with the sub-chamber and is formed in the mixed gas introduction pipe is formed at an end portion on a side away from the main combustion chamber of the sub-chamber.

3. The sub-chamber type gas engine according to claim 2, Wherein, The sub-chamber includes: A first region where an ignition portion of the spark plug is disposed and a mixed gas inlet port is formed; A second region where the plurality of injection holes are formed; and A third region formed between the first region and the second region, and having a smaller area orthogonal to the central axis of the sub-chamber than the first region.

4. The sub-chamber type gas engine according to claim 3, Wherein, On a cross-section along the central axis of the sub-chamber, the axis of the spark plug extends in the extending direction of the central axis of the sub-chamber.

5. The sub-chamber type gas engine according to claim 3, Wherein, On a cross-section along the central axis of the sub-chamber, the spark plug is inclined such that the distance of the axis of the spark plug from the central axis of the sub-chamber becomes shorter as it faces the main combustion chamber side.

6. The sub-chamber type gas engine according to any one of claims 2 to 5, Wherein, On a cross-section along the central axis of the sub-chamber, the mixed gas introduction pipe is inclined such that at least a part of the mixed gas inlet port is closer to the axis of the spark plug as it faces the mixed gas inlet port side.

7. The sub-chamber type gas engine according to any one of claims 2 to 5, Wherein, When viewed from one side in the extending direction of the central axis of the sub-chamber, at least a part of the mixed gas introduction pipe including the mixed gas inlet port extends toward the ignition portion of the spark plug.

8. The sub-chamber type gas engine according to any one of claims 2 to 5, Wherein, On a cross-section along the central axis of the sub-chamber, the ignition portion of the spark plug is located on an imaginary straight line passing through the center of the mixed gas inlet port.

9. The sub-chamber type gas engine according to any one of claims 1 to 5, further comprising: A compressor provided in the intake pipe and configured to compress the mixed gas, The connection portion of the intake pipe and the mixed gas introduction pipe is provided at a position more downstream than the compressor.

10. The auxiliary chamber type gas engine according to claim 9, further comprising: A gas fuel supply pipe connected to a position more upstream than the compressor of the intake pipe and for supplying the gas fuel; and A gas fuel introduction pipe branched from the gas fuel supply pipe and for introducing at least a part of the gas fuel flowing in the gas fuel supply pipe as the unburned fuel into the auxiliary chamber.

11. The auxiliary chamber type gas engine according to claim 10, wherein, the gas fuel introduction pipe is connected to the mixed gas introduction pipe, the auxiliary chamber type gas engine further comprises: A first backflow prevention device provided between the connection portion of the mixed gas introduction pipe and the intake pipe and the connection portion of the gas fuel introduction pipe, and preventing gas from flowing from the connection portion of the gas fuel introduction pipe toward the connection portion of the intake pipe; and A second backflow prevention device provided in the gas fuel introduction pipe and preventing gas from flowing from the connection portion of the mixed gas introduction pipe toward the connection portion of the gas fuel supply pipe.

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