engine

Abstract

To provide an engine that uses two types or more of fuel and can suppress damage of the engine caused by backfire.SOLUTION: An engine includes: an engine body; an intake line connected to a combustion chamber of the engine body; a first fuel line connected to the intake line and configured to supply first fuel to the intake line; and a second fuel line connected to a position on the downstream side of a position to which the first fuel line is connected in the intake line and configured to supply second fuel of which explosion lower limit is lower than that of the first fuel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to an engine.

Background Art

[0002] In recent years, engines using hydrogen or the like as fuel have been proposed for a decarbonized society. Patent Document 1 discloses an operating gas circulation type hydrogen engine that can operate with high thermal efficiency by removing products with a small specific heat ratio (for example, carbon dioxide) generated in a combustion chamber from circulating gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor of the present application has been studying a novel engine that uses two or more types of fuels. In such a novel engine, it is a problem to suppress damage to the engine due to backfire. The engine described in Patent Document 1 is an engine that uses only hydrogen as fuel, not an engine that uses two or more types of fuels, and no findings for solving the above problems are disclosed.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide an engine that can suppress damage to the engine due to backfire for an engine that uses two or more types of fuels.

Means for Solving the Problems

[0006] To achieve the above object, an engine according to at least one embodiment of the present disclosure includes an engine body, An intake line connected to the combustion chamber of the engine body, A first fuel line connected to the intake line and configured to supply the first fuel to the intake line, A second fuel line is connected to a position downstream of the position where the first fuel line is connected in the intake line, and is configured to supply a second fuel having a lower lower explosion limit than the first fuel, It is equipped with.

[0007] To achieve the above objective, the engine according to at least one embodiment of this disclosure is: An engine body including a main combustion chamber and a sub-combustion chamber communicating with the main combustion chamber, An intake line connected to the main combustion chamber of the engine body, A first fuel line connected to the intake line and configured to supply the first fuel to the intake line, A second fuel line is connected to the aforementioned sub-combustion chamber and configured to supply a second fuel having a lower explosive limit than the first fuel to the sub-combustion chamber, It is equipped with. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, an engine is provided that can suppress engine damage due to flashback in an engine using two or more types of fuel. [Brief explanation of the drawing]

[0009] [Figure 1] This figure schematically shows the general configuration of a gas engine according to several embodiments of the present disclosure. [Figure 2] This diagram schematically shows the range of influence of flashback in a gas engine of a comparative configuration. [Figure 3] This diagram schematically illustrates an example of the range of effects caused by flashback in a gas engine. [Modes for carrying out the invention]

[0010] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of the invention, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly describe such arrangements, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. For example, expressions describing shapes such as squares or cylinders shall not only represent geometrically precise shapes such as squares or cylinders, but also shapes that include protrusions, chamfers, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0011] (Outline configuration of a gas engine) Figure 1 is a schematic diagram showing the general configuration of a gas engine 2 according to several embodiments of the present disclosure.

[0012] As shown in Figure 1, the gas engine 2 comprises an engine body 4, an intake line 6, an exhaust line 8, a supercharger 10, and an air cooler 12.

[0013] In the example shown in FIG. 1, the gas engine 2 is a prechamber-type gas engine, and the engine body 4 includes a main combustion chamber 18 (main chamber) defined between a piston 14 and a cylinder head 16, and a sub-combustion chamber 26 (sub-chamber) communicating with the main combustion chamber 18. Further, the sub-combustion chamber 26 is a space formed inside a sub-chamber forming portion 28 and a sub-chamber base 31 provided in the cylinder head 16, and communicates with the main combustion chamber 18 through a plurality of injection holes 30 formed in the sub-chamber base 31.

[0014] The intake line 6 is connected to the main combustion chamber 18 and is configured to supply a mixture of at least one type of fuel gas and air (lean premixed gas) to the main combustion chamber 18. The intake line 6 includes an intake port 32 formed in the cylinder head 16 and an intake pipe 34 connected to the intake port 32. One end of the intake port 32 is connected to the main combustion chamber 18, and the other end of the intake port 32 is connected to the intake pipe 34. An intake valve 36 for controlling the communication state between the main combustion chamber 18 and the intake pipe 34 is provided in the intake port 32.

[0015] The supply of fuel gas to the sub-combustion chamber 26 (hereinafter referred to as sub-chamber fuel) is directly performed by a sub-chamber fuel line 29 connected to the sub-combustion chamber 26. Then, combustion flames are generated by ignition of the fuel (sub-chamber fuel and lean premixed gas flowing in from the main combustion chamber 18) in the sub-combustion chamber 26 by an ignition device (ignition plug 37 installed in the sub-chamber forming portion 28 in this embodiment), and the combustion flames are ejected from the sub-combustion chamber 26 to the main combustion chamber 18 through the plurality of injection holes 30, so that the fuel (lean premixed gas) in the main combustion chamber 18 is combusted.

[0016] The exhaust line 8 is connected to the main combustion chamber 18 and is configured to discharge the combustion gas generated by the combustion of fuel in the main combustion chamber 18 from the main combustion chamber 18 as exhaust gas. The exhaust line 8 includes an exhaust port 38 formed in the cylinder head 16 and an exhaust pipe 40 connected to the exhaust port 38. One end of the exhaust port 38 is connected to the main combustion chamber 18, and the other end of the exhaust port 38 is connected to the exhaust pipe 40. An exhaust valve 42 for controlling the communication state between the main combustion chamber 18 and the exhaust pipe 40 is provided in the exhaust port 38. The intake valve 36 and the exhaust valve 42 open and close the intake port 32 and the exhaust port 38 respectively according to the crank angle of a crankshaft (not shown).

[0017] The supercharger 10 includes a compressor 44 provided in the intake line 6, a turbine 46 provided in the exhaust line 8, and a rotating shaft 48 connecting the compressor 44 and the turbine 46. When the turbine 46 is driven by the exhaust gas flowing through the exhaust line 8, the rotation of the turbine 46 is transmitted to the compressor 44 via the rotating shaft 48, and the compressor 44 compresses the air flowing through the intake line 6.

[0018] The air cooler 12 is provided between the compressor 44 and the engine body 4 (between the compressor 44 and the intake port 32) in the intake line 6 and is configured to cool the air heated by the compression in the compressor 44.

[0019] (Configuration example of the fuel line of a gas engine) In some embodiments, the above-described gas engine 2 may be configured to supply two or more types of fuel gas to the intake line 6. In this case, the gas engine 2 includes two or more of the fuel lines 50a to 50d shown by the dashed lines in FIG. 1.

[0020] In FIG. 1, the fuel line 50a is connected to a position Pa upstream of the compressor 44 in the intake line 6. The fuel line 50b is connected to a position Pb downstream of the compressor 44 in the intake line 6. Specifically, the position Pb is a position between the compressor 44 and the air cooler 12 in the intake line 6.

[0021] Fuel line 50c is connected to position Pc downstream of compressor 44 in intake line 6. Position Pc is, more specifically, located between the air cooler 12 and cylinder head 16 in intake line 6. Fuel line 50d is connected to position Pd downstream of compressor 44 in intake line 6. Position Pd is, more specifically, located between the air cooler 12 and intake valve 36 in intake line 6, and more specifically, located at intake port 32 in intake line 6.

[0022] Below, several embodiments will be described using the example of a case where the gas engine 2 is equipped with two of the fuel lines 50a to 50d.

[0023] In some embodiments described below, the fuel line connected to the relatively upstream position in the intake line 6 is defined as the first fuel line, and the fuel line connected to the relatively downstream position in the intake line 6 (a position downstream of the point where the intake line 6 and the first fuel line connect) is defined as the second fuel line. The fuel gas supplied from the first fuel line to the intake line 6 (i.e., the main component of the gas supplied from the first fuel line to the intake line 6) is defined as the first fuel, and the fuel gas supplied from the second fuel line to the intake line 6 (i.e., the main component of the gas supplied from the second fuel line to the intake line 6) is defined as the second fuel. The second fuel line is configured to supply the second fuel, which has a lower lower explosion limit than the first fuel, to the intake line 6. In other words, the lower explosion limit of the second fuel supplied to the intake line 6 from the second fuel line, which is connected to the relatively downstream position in the intake line 6, is lower than the lower explosion limit of the first fuel supplied to the intake line 6 from the first fuel line, which is connected to the relatively upstream position in the intake line 6.

[0024] For example, the gas engine 2 shown in Figure 1 may have fuel line 50a as the first fuel line, and fuel line 50b, fuel line 50c, or fuel line 50d as the second fuel lines. That is, the gas engine 2 may have fuel line 50a as the first fuel line and fuel line 50b as the second fuel line, or fuel line 50a as the first fuel line and fuel line 50c as the second fuel line, or fuel line 50a as the first fuel line and fuel line 50d as the second fuel line.

[0025] Alternatively, the gas engine 2 shown in Figure 1 may be equipped with fuel line 50b or fuel line 50c as a first fuel line, and a second fuel line which is connected to a position downstream of the position where it connects to the first fuel line in the intake line 6, among fuel line 50b, fuel line 50c, or fuel line 50d. For example, the gas engine 2 may be equipped with fuel line 50b as a first fuel line and fuel line 50c as a second fuel line, or fuel line 50b as a first fuel line and fuel line 50d as a second fuel line, or fuel line 50c as a first fuel line and fuel line 50d as a second fuel line.

[0026] Furthermore, the first and second fuels described above may be any two of the following: hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia. That is, the first fuel may be any of hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia, and the second fuel may be any of the following with a lower explosive limit than that of the first fuel. For example, the first fuel may be methane and the second fuel may be hydrogen. Also, for example, the first fuel may be ammonia and the second fuel may be methane. The lower explosive limits of hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia are 4.0%, 5.0%, 2.1%, 1.8%, 12.5%, and 15.0%, respectively. Furthermore, the concentration of the first fuel in the gas flowing through the first fuel line and the concentration of the second fuel in the gas flowing through the second fuel line may be, for example, 50% or more, or 80% or more, respectively.

[0027] Here, we will explain the technical significance of making the lower explosion limit of the second fuel supplied to the intake line 6 from the second fuel line connected to a relatively downstream position in the intake line 6 lower than the lower explosion limit of the first fuel supplied to the intake line 6 from the first fuel line connected to a relatively upstream position in the intake line 6.

[0028] Since the second fuel has a lower explosive limit than the first fuel, it is more prone to flashback. Therefore, by connecting the second fuel line to the intake line 6 downstream of the connection point of the first fuel line in the intake line 6, as described above, the area affected by flashback in the intake line 6 can be reduced, thereby suppressing damage to the gas engine 2 due to flashback (this point will be explained in more detail later).

[0029] Furthermore, the pressure in the intake line 6 is lowest at Pa upstream of the compressor 44 and highest at Pb downstream of the compressor. Subsequently, the pressure decreases due to pressure loss at Pc after the air cooler 12 and Pd in ​​the intake port 32. That is, the relationship is Pb > Pc > Pd > Pa. Therefore, if the point where the fuel line connects to the intake line 6 is Pa, the fuel supply pressure, which is the pressure of the fuel flowing through the fuel line, can be lowered, and the energy required to boost the fuel pressure can be saved. For this reason, as described above, the first fuel, which has a relatively higher lower explosion limit than the first fuel, is less prone to flashback. By setting the point where the first fuel line connects to the intake line 6 to Pa, the risk of flashback can be suppressed while saving the energy used to boost the first fuel pressure.

[0030] The above effects will be explained in detail in comparison with the comparative form. As shown in the comparative configuration in Figure 2, when a fuel with a low lower explosion limit (e.g., hydrogen) is supplied from, for example, fuel line 50a, and a fuel with a high lower explosion limit (e.g., methane) is supplied from, for example, fuel line 50c, if a flashback occurs when the intake valve 36 opens and the gas in the high-temperature main combustion chamber 18 ignites the air-fuel mixture in the intake port 32, causing the flame to travel upstream of the intake line 6, the flashback may travel as far as the point Pa where the fuel line 50a connects to the intake line 6 (the upstream end of the range where the air-fuel mixture containing the fuel with a low lower explosion limit exists). Because the burning volume is large and the effects of the flashback extend over a wide area, damage to the gas engine due to flashback is likely to occur.

[0031] In contrast, as illustrated in Figure 3, when a fuel with a high lower explosive limit (e.g., methane) is supplied from, for example, fuel line 50a, and a fuel with a low lower explosive limit (e.g., hydrogen) is supplied from, for example, fuel line 50c, even if a flashback occurs, it is unlikely that the flashback will travel upstream of the point Pc where fuel line 50c connects in the intake line 6. Therefore, as shown in Figure 3, the range in which combustion due to flashback may occur can be narrowed compared to the comparative configuration shown in Figure 2, thereby suppressing damage to the gas engine 2 due to flashback. Furthermore, supplying fuel from fuel line 50c to point Pc, which is closer to the main combustion chamber 18, can increase the response speed of the gas engine 2. In addition, since fuels with a high lower explosive limit (e.g., methane) are less prone to flashback, supplying fuel from fuel line 50a to the upstream point Pa, where the pressure in the intake line 6 is lower, can reduce the risk of flashback while saving energy used to pressurize the fuel.

[0032] The following describes other effects that can be obtained by some of the embodiments described above. If the gas engine 2 shown in Figure 1 is equipped with, for example, fuel line 50a as the first fuel line, and fuel lines 50b, 50c, or 50d as the second fuel lines, the first fuel line is connected to a position upstream of the compressor 44 in the intake line 6, and the second fuel line is connected to a position downstream of the compressor 44 in the intake line 6. Therefore, the first fuel, which has a higher lower explosive limit (lower risk of flashback), can be supplied to a position Pa upstream of the compressor 44 in the intake line 6. This suppresses the effect of flashback on the compressor 44 compared to when the second fuel is supplied to a position Pa upstream of the compressor 44 in the intake line 6. In addition, by supplying the first fuel to a position Pa in the intake line 6 where the pressure is relatively low before compression by the compressor 44, the fuel supply pressure of the first fuel can be lowered, and the energy required to boost the pressure of the first fuel can be saved. Furthermore, by supplying the second fuel, which has a lower lower explosive limit (and therefore a higher risk of flashback), to the intake line 6 at a location downstream of the compressor 44, the effect of flashback on the compressor 44 can be suppressed, thereby reducing the risk of damage to the supercharger 10. In addition, it is possible to manufacture the gas engine 2 according to this embodiment by modifying an existing engine that has a fuel line connected to a location upstream of the compressor 44 in the intake line 6.

[0033] Furthermore, if the gas engine 2 shown in Figure 1 is equipped with, for example, fuel line 50a as the first fuel line and fuel line 50c or fuel line 50d as the second fuel line, the second fuel line is connected to a position between the air cooler 12 and the intake valve 36 in the intake line 6. Therefore, the second fuel, which has a lower lower explosion limit (higher risk of flashback) than the first fuel, can be supplied to a position between the air cooler 12 and the intake valve 36 in the intake line 6. As a result, even if flashback occurs, the area affected by the flashback can be limited to the range from the intake valve 36 to after the air cooler 12, thereby suppressing damage to the gas engine 2.

[0034] Furthermore, if the gas engine 2 shown in Figure 1 is equipped with, for example, fuel line 50a as the first fuel line and fuel line 50b as the second fuel line, the second fuel line is connected to the intake line 6 at a position between the compressor 44 and the air cooler 12. In this case, since the second fuel line can be connected to the intake line 6 outside the engine body 4, it is easier to supply fuel from the second fuel line to the intake line 6. Also, as mentioned above, even if flashback occurs, the flame will not travel back to the compressor 44, reducing the risk of damage to the supercharger 10.

[0035] Furthermore, if the gas engine 2 shown in Figure 1 is equipped with, for example, fuel line 50a as the first fuel line and fuel line 50d as the second fuel line, the second fuel line is connected to the intake port 32. Therefore, if a flashback occurs due to the second fuel, the effect of the flashback will not extend to the outside of the engine body 4, and damage to the gas engine 2 can be effectively suppressed.

[0036] Furthermore, if the gas engine 2 shown in Figure 1 is equipped with, for example, fuel line 50b as the first fuel line and fuel line 50c as the second fuel line, or if fuel line 50b is equipped with fuel line 50d as the first fuel line and fuel line 50d as the second fuel line, then the first fuel line is connected to a position between the compressor 44 and the intake valve 36 in the intake line 6, and the second fuel line is connected to a position downstream of the position where the first fuel line and the intake line 6 are connected in the intake line 6. In this case, it is possible to manufacture the gas engine 2 according to this embodiment by modifying an existing gas engine that has a fuel line connected to a position between the compressor 44 and the intake valve 36 in the intake line 6.

[0037] (Other fuel line configurations for gas engines) In some embodiments, the gas engine 2 shown in Figure 1 may supply fuel to the intake line 6 that is different from the fuel supplied from the pre-chamber fuel line 29. In this case, the gas engine 2 may have one or more of the fuel lines 50a to 50d described with reference to Figure 1, and the pre-chamber fuel line 29 may be configured to supply fuel gas with a lower explosive limit than the fuel gas supplied to the intake line 6 from the one or more fuel lines to the pre-combustion chamber 26.

[0038] For example, the fuel supplied to the intake line 6 from one or more of the fuel lines 50a to 50d may be any of hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia, and the sub-chamber fuel supplied to the sub-combustion chamber 26 from the sub-chamber fuel line 29 may be any of hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia, and may have a lower lower explosion limit than the fuel supplied to the intake line 6 from one or more of the fuel lines. For example, methane may be supplied to the intake line 6 from one or more of the fuel lines 50a to 50d, and hydrogen may be supplied to the sub-combustion chamber 26 from the sub-chamber fuel line 29. Alternatively, for example, ammonia may be supplied to the intake line 6 from one or more of the fuel lines 50a to 50d, and methane may be supplied to the sub-combustion chamber 26 from the sub-chamber fuel line 29.

[0039] In a sub-chamber type gas engine 2, which includes a main combustion chamber 18 and a sub-combustion chamber 26, there is basically no air in the sub-chamber fuel line 29 that supplies fuel to the sub-combustion chamber 26, or if there is, it is only in a small amount. Therefore, even if fuel with a lower lower explosion limit and a higher likelihood of flashback is supplied to the sub-combustion chamber 26 from the sub-chamber fuel line 29, as described above, the risk of flashback is low. Also, as described above, by supplying fuel gas with a higher lower explosion limit and a lower likelihood of flashback to the intake line 6, the risk of flashback is lower than when the same fuel gas as the sub-chamber fuel is supplied to the intake line 6. Therefore, damage to the gas engine 2 caused by flashback can be suppressed.

[0040] Below, several embodiments will be described using the example of a case where the gas engine 2 is equipped with one of the fuel lines 50a to 50d. In the embodiments described below, one of the fuel lines 50a to 50d equipped with the gas engine 2 corresponds to the first fuel line, and the pre-chamber fuel line 29 corresponds to the second fuel line. Furthermore, the fuel gas supplied from one of the fuel lines 50a to 50d equipped with the gas engine 2 to the intake line 6 corresponds to the first fuel, and the fuel gas supplied from the pre-chamber fuel line 29 to the pre-combustion chamber 26 corresponds to the second fuel.

[0041] In one embodiment, the gas engine 2 shown in Figure 1 may be equipped with a fuel line 50a as one of the fuel lines. In this case, the sub-chamber fuel line 29 is configured to supply the sub-combustion chamber 26 with fuel gas that has a lower lower explosion limit than the fuel gas supplied from the fuel line 50a to the intake line 6. This makes it possible to suppress damage to the gas engine 2 caused by flashback, as described above. Furthermore, by supplying fuel gas with a higher lower explosion limit (lower risk of flashback) than the sub-chamber fuel to the intake line 6 at a position upstream of the compressor 44, the effect of flashback on the compressor 44 can be suppressed more effectively than when the same fuel as the sub-chamber fuel is supplied at a position upstream of the compressor 44. In addition, by supplying fuel gas at a relatively low pressure position Pa in the intake line 6 before compression by the compressor 44, the fuel supply pressure of the fuel gas can be lowered, and the energy required to boost the pressure of the fuel gas can be saved.

[0042] In some embodiments, the gas engine 2 shown in Figure 1 may be equipped with any of the fuel lines 50b to 50d as one of the fuel lines. In this case, the sub-chamber fuel line 29 is configured to supply the sub-combustion chamber 26 with a fuel gas whose lower explosive limit is lower than the fuel gas supplied to the intake line 6 from any of the fuel lines 50b to 50d provided by the gas engine 2.

[0043] This makes it possible to suppress damage to the gas engine 2 caused by flashback, as described above. Furthermore, by supplying fuel gas with a higher lower explosive limit (lower risk of flashback) than the pre-chamber fuel to the intake line 6 at a location downstream of the compressor 44, the effect of flashback on the compressor 44 can be effectively suppressed, and the risk of damage to the supercharger 10 can be effectively reduced. In addition, it becomes possible to manufacture by modifying existing engines in which the fuel line is connected at a location downstream of the compressor 44 in the intake line 6.

[0044] In some embodiments, the gas engine 2 shown in Figure 1 may be equipped with a fuel line 50b as one of the fuel lines. In this case, the sub-chamber fuel line 29 is configured to supply the sub-combustion chamber 26 with fuel gas that has a lower explosive limit than the fuel gas supplied from the fuel line 50b to the intake line 6. This makes it easier to supply fuel from the fuel line 50b to the intake line 6 because the fuel line 50b can be connected to the intake line 6 outside the engine body 4. Furthermore, as described above, even if flashback occurs, the flame will not travel back to the compressor 44, reducing the risk of damage to the supercharger 10.

[0045] In some embodiments, the gas engine 2 shown in Figure 1 may be equipped with fuel line 50c or 50d as one of the fuel lines. In this case, the sub-chamber fuel line 29 is configured to supply the sub-combustion chamber 26 with fuel gas that has a lower explosive limit than the fuel gas supplied from fuel line 50c or 50d to the intake line 6. This makes it possible to limit the range affected by flashback to the area from the intake valve 36 to after the air cooler 12, thereby suppressing damage to the gas engine 2.

[0046] In some embodiments, the gas engine 2 shown in Figure 1 may be equipped with a fuel line 50d as one of the fuel lines. In this case, the sub-chamber fuel line 29 is configured to supply the sub-combustion chamber 26 with fuel gas that has a lower explosive limit than the fuel gas supplied from the fuel line 50d to the intake line 6. This suppresses the effect of flashback occurring outside the engine body 4 in the event of a flashback caused by the fuel gas supplied to the intake line 6, and effectively suppresses damage to the gas engine 2.

[0047] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0048] For example, a gas engine may supply three or more types of fuel to the intake line 6. In this case, for the three or more types of fuel, the position where the fuel is supplied to the intake line 6 may be further downstream as the lower explosion limit of the fuel decreases. For example, a gas engine may include a first fuel line connected to the intake line and supplying a first fuel to the intake line, a second fuel line connected downstream of the position where the first fuel line connects in the intake line and supplying a second fuel to the intake line, and a third fuel line connected downstream of the position where the second fuel line connects in the intake line and supplying a third fuel to the intake line. In this case, the lower explosion limit of the second fuel may be lower than that of the first fuel, and the lower explosion limit of the third fuel may be lower than that of the second fuel. This can suppress damage to the gas engine 2 due to flashback and save energy used to pressurize the fuel.

[0049] Furthermore, the gas engine does not have to be a pre-chamber type gas engine, and the gas engine does not have to have a pre-combustion chamber. In this case, for example, the gas engine may have an intake line connected to the combustion chamber of the engine body, a first fuel line connected to the intake line, and a second fuel line connected to the combustion chamber. In this case, the second fuel line may supply to the combustion chamber a second fuel having a lower explosive limit than the first fuel supplied from the first fuel line to the intake line. This makes it possible to suppress damage to the gas engine 2 due to flashback.

[0050] Furthermore, this disclosure is applicable not only to gas engines but also to diesel engines, for example. Note that the term "lower explosive limit" mentioned above may be interpreted as "lower limit of flammability" or "lower limit of combustion." Similarly, "low lower explosive limit" may be interpreted as "high explosion class." A high explosion class takes precedence over a low lower explosive limit. If the explosion classes are the same, the lower explosive limit is used for determination.

[0051] The contents described in each of the above embodiments can be understood, for example, as follows:

[0052] (1) An engine according to at least one embodiment of the present disclosure (e.g., the gas engine 2 described above) The engine body (for example, the engine body 4 mentioned above) An intake line (for example, the intake line 6 described above) connected to the combustion chamber of the engine body (for example, the main combustion chamber 18 described above), A first fuel line (for example, any of the fuel lines 50a to 50d described above) is connected to the intake line and configured to supply a first fuel (for example, any of the above-mentioned hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia) to the intake line, A second fuel line (for example, one of the fuel lines 50a to 50d described above, which is connected to a position downstream of the position where the first fuel line is connected in the intake line) is configured to supply a second fuel having a lower lower explosive limit than the first fuel (for example, one of the hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia described above, which has a lower lower explosive limit than the first fuel), It is equipped with.

[0053] Since the second fuel has a lower explosive limit than the first fuel, it is more prone to flashback than the first fuel. Therefore, by connecting the second fuel line in the intake line downstream of the connection point of the first fuel line in the intake line, as described in (1) above, the area affected by flashback in the intake line can be reduced, thereby suppressing engine damage caused by flashback. Furthermore, as described in (1) above, since the first fuel has a relatively higher lower explosive limit than the first fuel, flashback is less likely to occur. Therefore, even if the position where the first fuel line is connected in the intake line is upstream of the position where the second fuel line is connected in the intake line, the increased risk of flashback can be suppressed.

[0054] (2) In some embodiments, in the engine described in (1) above, The system further includes a supercharger (e.g., the supercharger 10 described above) which includes a compressor (e.g., the compressor 44 described above) for compressing the air flowing through the intake line, The first fuel line (for example, the fuel line 50a described above) is connected to a position upstream of the compressor in the intake line (for example, position Pa described above), The second fuel line (for example, fuel line 50b, fuel line 50c, or fuel line 50d described above) is connected to a position downstream of the compressor in the intake line (for example, position Pb, position Pc, or position Pd described above).

[0055] According to the engine described in (2) above, by supplying the first fuel, which has a higher lower explosive limit (lower risk of flashback) than the first fuel, to the intake line upstream of the compressor, the effect of flashback on the compressor can be suppressed. In addition, by supplying the first fuel at a relatively low pressure position in the intake line before compression by the compressor, the fuel supply pressure of the first fuel can be lowered, and the energy required to boost the pressure of the first fuel can be saved. Furthermore, by supplying the second fuel (which has a lower lower explosion limit and therefore a higher risk of flashback) to the intake line downstream of the compressor, the effect of flashback on the compressor can be suppressed, thereby reducing the risk of damage to the turbocharger. Furthermore, it is also possible to manufacture this engine by modifying an existing engine in which the fuel line is connected upstream of the compressor in the intake line.

[0056] (3) In some embodiments, in the engine described in (2) above, The system further includes an air cooler (for example, the air cooler 12 described above) provided between the compressor and the engine body in the intake line, The second fuel line is connected to the intake line at a position between the air cooler and the intake valve of the engine body (for example, the intake valve 36 described above).

[0057] According to the engine described in (3) above, even if flashback occurs, the range affected by the flashback can be limited to the area from the intake valve to after the air cooler, thereby suppressing engine damage.

[0058] (4) In some embodiments, in the engine described in any of (2) above, The system further includes an air cooler (for example, the air cooler 12 described above) provided between the compressor and the engine body in the intake line, The second fuel line (for example, the fuel line 50b described above) is connected to the intake line at a position between the compressor and the air cooler (for example, position Pb described above).

[0059] According to the engine described in (4) above, the position between the compressor and the air cooler in the intake line is outside the engine body, making it easier to supply fuel from the second fuel line to the intake line. Furthermore, even if flashback occurs, the flame will not travel back to the compressor, reducing the risk of damage to the supercharger.

[0060] (5) In some embodiments, in the engine described in any of (1) to (3) above, The second fuel line (for example, the fuel line 50d described above) is connected to an intake port (for example, the intake port 32 described above) formed in the cylinder head of the engine body.

[0061] According to the engine described in (5) above, if a flashback occurs, the effects of the flashback will be suppressed from extending to the outside of the engine body, and engine damage can be effectively suppressed.

[0062] (6) In some embodiments, in the engine described in (1) above, The system further includes a supercharger (e.g., the supercharger 10 described above) which includes a compressor (e.g., the compressor 44 described above) for compressing the air flowing through the intake line, The first fuel line (for example, fuel line 50b, fuel line 50c, or fuel line 50d described above) is connected to the intake line at a position between the compressor and the intake valve of the engine body (for example, the intake valve 36 described above), The second fuel line (fuel line 50b, fuel line 50c, or fuel line 50d, which is connected downstream of the point in the intake line where the first fuel line and the intake line 6 are connected) is connected downstream of the point in the intake line where the first fuel line and the intake line are connected.

[0063] According to the engine described in (6) above, it can be easily manufactured when modifying an existing engine that has a fuel line connected to a position between the compressor and the intake valve of the engine body in the intake line.

[0064] (7) An engine according to at least one embodiment of the present disclosure is An engine body (e.g., the engine body 4 described above) includes a main combustion chamber (e.g., the main combustion chamber 18 described above) and a sub-combustion chamber (e.g., the sub-combustion chamber 26 described above) that communicates with the main combustion chamber, An intake line (for example, the intake line 6 described above) connected to the main combustion chamber of the engine body, A first fuel line (for example, any of the fuel lines 50a to 50d described above) is connected to the intake line and configured to supply a first fuel (for example, any of the above-mentioned hydrogen, methane, propane, n-butane, carbon monoxide, and ammonia) to the intake line, A second fuel line (for example, the aforementioned sub-chamber fuel line 29) is connected to the sub-combustion chamber and configured to supply a second fuel having a lower explosive limit than the first fuel to the sub-combustion chamber, It is equipped with.

[0065] In a so-called sub-chamber engine, which includes a main combustion chamber and a sub-combustion chamber, there is basically no air in the fuel supply line to the sub-combustion chamber, or if there is, it is only in a small amount. Therefore, as described in (7) above, even if the second fuel, which has a lower lower explosion limit than the first fuel and is more prone to flashback, is supplied to the sub-combustion chamber from the second fuel line, the risk of flashback is low. Furthermore, as described in (7) above, by supplying the first fuel, which has a higher lower explosive limit and is less prone to flashback than the second fuel, from the first fuel line to the intake line, the risk of flashback is reduced compared to supplying the second fuel, which is more prone to flashback, to the intake line. Therefore, engine damage caused by flashback can be suppressed.

[0066] (8) In some embodiments, in the engine described in (7) above, The system further includes a supercharger (e.g., the supercharger 10 described above) which includes a compressor (e.g., the compressor 44 described above) for compressing the air flowing through the intake line, The first fuel line (for example, the fuel line 50a described above) is connected to a position upstream of the compressor in the intake line (for example, position Pa described above).

[0067] According to the engine described in (8) above, by supplying the first fuel, which has a higher lower explosive limit (lower risk of flashback) than the first fuel, to the intake line upstream of the compressor, the effect of flashback on the compressor can be suppressed. In addition, by supplying the first fuel at a relatively low pressure position in the intake line before compression by the compressor, the fuel supply pressure of the first fuel can be lowered, and the energy required to boost the pressure of the first fuel can be saved. Furthermore, it is also possible to manufacture this engine by modifying an existing engine in which the fuel line is connected upstream of the compressor in the intake line.

[0068] (9) In some embodiments, in the engine described in (7) above, The system further includes a supercharger (e.g., the supercharger 10 described above) which includes a compressor (e.g., the compressor 44 described above) for compressing the air flowing through the intake line, The first fuel line (for example, any of the fuel lines 50b to 50d described above) is connected to a position downstream of the compressor in the intake line (for example, position Pb, position Pc, or position Pd described above).

[0069] According to the engine described in (9) above, by supplying the first fuel, which has a higher lower explosive limit (lower risk of flashback) than the first fuel, to the intake line downstream of the compressor, the effect of flashback on the compressor can be effectively suppressed, and the risk of damage to the supercharger can be effectively reduced. Furthermore, it is possible to manufacture this engine by modifying existing engines in which the fuel line is connected downstream of the compressor in the intake line.

[0070] (10) In some embodiments, in the engine described in (9) above, The system further includes an air cooler (for example, the air cooler 12 described above) provided between the compressor and the engine body in the intake line, The first fuel line is connected to the intake line at a location between the compressor and the air cooler (for example, location Pb as described above).

[0071] According to the engine described in (10) above, the position between the compressor and the air cooler in the intake line is outside the engine body, making it easier to supply fuel from the first fuel line to the intake line. Furthermore, even if flashback occurs, the flame will not travel back to the compressor, reducing the risk of damage to the supercharger.

[0072] (11) In some embodiments, in the engine described in (9) above, The system further includes an air cooler (for example, the air cooler 12 described above) provided between the compressor and the engine body in the intake line, The first fuel line (for example, the fuel line 50d described above) is connected to an intake port (for example, the intake port 32 described above) formed in the cylinder head of the engine body.

[0073] According to the engine described in (11) above, if a flashback occurs, the effects of the flashback will be suppressed from extending to the outside of the engine body, and engine damage can be effectively suppressed.

[0074] (12) In some embodiments, in the engine described in any of (1) to (11) above, The first fuel is methane, The first fuel is hydrogen.

[0075] According to the engine described in (12) above, carbon dioxide emissions can be reduced by using hydrogen compared to conventional engines that use only methane as fuel. In addition, although hydrogen has a lower lower explosive limit and a higher combustion rate than methane, by supplying hydrogen to a location where the impact area is smaller even if flashback occurs compared to methane, engine damage caused by flashback due to hydrogen can be suppressed.

[0076] (13) In some embodiments, in the engine described in any of (1) to (11) above, The first fuel is ammonia, The second fuel is methane.

[0077] According to the engine described in (13) above, carbon dioxide emissions can be reduced by using ammonia compared to conventional engines that use only methane as fuel. Furthermore, since ammonia has a higher lower explosive limit and a lower combustion rate than methane, supplying ammonia as far upstream as possible in the intake line does not significantly increase the risk of flashback, and if the ammonia fuel injection point is set to Pa upstream of the compressor 44, energy used to pressurize the first fuel can be saved.

[0078] (14) In some embodiments, in the engine described in any of (1) to (11) above, The first fuel is ammonia, The first fuel is hydrogen.

[0079] According to the engine described in (14) above, carbon dioxide emissions can be reduced by using ammonia and hydrogen compared to conventional engines that use methane alone as fuel. Furthermore, since ammonia has a higher lower explosive limit and a lower combustion rate than methane, supplying ammonia as far upstream as possible in the intake line does not significantly increase the risk of flashback, and if the ammonia fuel is added at Pa upstream of the compressor 44, energy used to pressurize the first fuel can be saved. Since ammonia is difficult to ignite on its own, ignition can be improved by using hydrogen as the second fuel. [Explanation of symbols]

[0080] 2 Gas engines 4. Engine body 6. Intake line 8 Exhaust lines 10 Supercharger 12 Air cooler 14 pistons 16 Cylinder head 18 Main combustion chamber 26. Sub-combustion chamber 28 Subchamber formation part 29. Sub-chamber fuel line 30 nozzles 31 Antechamber cap 32 intake ports 34 Intake pipe 36 Intake valve 37 Spark plugs 38 exhaust ports 40 Exhaust pipe 42 Exhaust valve 44 Compressor 46 Turbine 48 Rotation axes 50a, 50b, 50c, 50d fuel lines Pb,Pc,Pd position

Claims

1. The engine body and An intake line connected to the combustion chamber of the engine body, A first fuel line is connected to the intake line and configured to supply the first fuel to the intake line, A second fuel line is connected to a position downstream of the position where the first fuel line is connected in the intake line, and is configured to supply a second fuel having a lower lower explosion limit than the first fuel, A supercharger including a compressor for compressing the air flowing through the intake line, An air cooler is provided between the compressor and the engine body in the intake line, Equipped with, The intake line includes an intake port formed in the cylinder head of the engine body and an intake pipe connected to the intake port. The first fuel line is connected to the intake line at a position upstream of the compressor, The second fuel line is connected to the intake line at a position downstream of the compressor, The second fuel line is connected to the intake port of the intake line at a position between the air cooler and the intake valve of the engine body in the intake line, The first fuel is methane or ammonia, The first two fuels are hydrogen. engine.

2. An engine body including a main combustion chamber and a sub-combustion chamber communicating with the main combustion chamber, An intake line connected to the main combustion chamber of the engine body, A first fuel line is connected to the intake line and configured to supply the first fuel to the intake line, A second fuel line is connected to the aforementioned sub-combustion chamber and configured to supply a second fuel having a lower explosive limit than the first fuel to the sub-combustion chamber, Equipped with, The intake line includes an intake port formed in the cylinder head of the engine body and an intake pipe connected to the intake port. The supercharger further includes a compressor for compressing the air flowing through the intake line, The first fuel line is connected to the intake line at a position downstream of the compressor, The intake line further comprises an air cooler provided between the compressor and the engine body, The first fuel line is connected to the intake port of the intake line at a position between the air cooler and the intake valve of the engine body in the intake line, The first fuel is methane, The first two fuels are hydrogen. engine.

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