gas engine

Abstract

To provide a gas engine which can suppress a backflow of a flame to an intake system when a backfire is generated while suppressing a pressure loss which occurs at the intake system.SOLUTION: A gas engine comprises: a throttle valve 91 arranged at an intake system and controlling an intake amount by being opened and closed; an intake manifold 8 arranged at a downstream side of the throttle valve 91 of the intake system, and introducing an air-fuel mixture containing gas fuel and intake air toward a cylinder of a cylinder block; a cylinder head assembled to the intake manifold 8, having an intake port, and introducing the air-fuel mixture which is supplied from the inkjet manifold 8 to the cylinder through the intake port; and a backfire prevention device 83 arranged at the downstream side of the throttle valve 91 of the intake system, and suppressing a backflow of a flame which is generated due to inflammation to the gas fuel which remains in the intake port toward an upstream side of the intake system.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a gas engine that runs on gaseous fuel. [Background technology]

[0002] Patent Document 1 discloses an engine fueled by hydrogen gas. In such an engine, a mixture of hydrogen gas and air can cause abnormal combustion (backfire) near the engine's combustion chamber when the engine is started or while it is running. If a backfire occurs, there is a risk that the flame will flow back into the intake system. Therefore, the engine described in Patent Document 1 is equipped with a backfire prevention device. The backfire prevention device described in Patent Document 1 is connected to the air intake of the carburetor and is in close contact with the carburetor body.

[0003] However, if a backfire prevention device is connected to the air intake of the carburetor, there is a risk of pressure loss occurring in the intake system. Therefore, the engine described in Patent Document 1 has room for improvement in terms of suppressing pressure loss in the intake system and suppressing flames from flowing back into the intake system when backfire occurs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-149559 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a gas engine that can suppress pressure loss in the intake system while preventing flames from flowing back into the intake system when a backfire occurs. [Means for solving the problem]

[0006] A first aspect of the present invention is a gas engine that runs on gaseous fuel, comprising: a throttle valve provided in an intake system that opens and closes to control the amount of intake air; an intake manifold provided downstream of the throttle valve in the intake system that directs a mixture containing the gaseous fuel and intake air toward the cylinders in a cylinder block; a cylinder head that is assembled to the intake manifold and has an intake port that directs the mixture supplied from the intake manifold to the cylinders through the intake port; and a backfire prevention device provided downstream of the throttle valve in the intake system that prevents a flame generated by ignition of the gaseous fuel remaining in the intake port from flowing back toward the upstream of the intake system.

[0007] According to a first aspect of the present invention, a backfire prevention device is provided downstream of a throttle valve in an intake system, and prevents a flame generated by ignition of gaseous fuel remaining in an intake port of a cylinder head from flowing back toward the upstream side of the intake system. In the first aspect of the present invention, the backfire prevention device can be installed in a location in the intake system with a relatively large flow passage area, thereby suppressing pressure loss in the intake system and preventing a flame from flowing back into the intake system in the event of a backfire.

[0008] A second aspect of the present invention is a gas engine characterized in that, in the first aspect of the present invention, the intake manifold has an intake body that temporarily stores the intake air that has passed through the throttle valve, and a plurality of intake pipes that are connected to the intake body and distribute the intake air guided from the intake body to a plurality of the cylinders, and the backfire prevention device is provided between the throttle valve and the intake body.

[0009] According to the second aspect of the present invention, the flashback prevention device is provided between the throttle valve and the intake main body of the intake manifold, so it is possible to install the flashback prevention device in a location in the intake system with a relatively large flow area. As a result, pressure loss in the intake system can be sufficiently reduced, and flames can be prevented from flowing back into the intake system when backfire occurs.

[0010] A third aspect of the present invention is a gas engine according to the first aspect of the present invention, further comprising an injector attached to the intake manifold for injecting the gaseous fuel into the intake system, the intake manifold having an intake body for temporarily storing the intake air that has passed through the throttle valve, and a plurality of intake pipes connected to the intake body for distributing the intake air guided from the intake body to a plurality of the cylinders, and the backfire prevention device being provided between the intake body and the injector.

[0011] According to the third aspect of the present invention, a backfire prevention device is provided between the intake body of the intake manifold and the injector, thereby suppressing pressure loss in the intake system and more reliably preventing flames generated by ignition of gaseous fuel remaining in the intake port of the cylinder head from flowing back upstream in the intake system.

[0012] A fourth aspect of the present invention is a gas engine according to the third aspect of the present invention, characterized in that the intake main body is provided as a separate body from the intake pipe and is removable from the intake pipe.

[0013] According to the fourth aspect of the present invention, the intake body is provided as a separate body from the intake pipe and is removable from the intake pipe. Therefore, by removing the intake body from the intake pipe, workers can easily install a backfire prevention device between the intake body of the intake manifold and the injector, and remove the backfire prevention device from between the intake body of the intake manifold and the injector.

[0014] A fifth aspect of the present invention is a gas engine characterized in that, in the first aspect of the present invention, it further comprises an injector attached to the intake manifold for injecting the gas fuel into the intake system, and the backfire prevention device is provided between the injector and the cylinder head.

[0015] According to the fifth aspect of the present invention, the backfire prevention device is provided between the injector and the cylinder head, thereby suppressing pressure loss in the intake system while more reliably preventing the flame in the combustion chamber from igniting the gaseous fuel remaining in the intake port of the cylinder head, and more reliably preventing the flame from flowing back upstream in the intake system. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a gas engine that can suppress pressure loss occurring in the intake system while suppressing flames from flowing back into the intake system when backfire occurs. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view illustrating a gas engine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the intake manifold of the present embodiment as viewed from the intake body side. [Figure 3] FIG. 2 is a perspective view of the intake manifold of the present embodiment, viewed from the intake pipe side. [Figure 4] 1 is an exploded perspective view showing a first example of a flashback prevention device according to an embodiment of the present invention. [Figure 5] FIG. 2 is an exploded perspective view showing a second example of the flashback prevention device of the present embodiment. [Figure 6] FIG. 10 is a perspective view showing a third example of the flashback prevention device of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiments described below are preferred examples of the present invention, and therefore various technically preferable limitations are applied thereto, but the scope of the present invention is not limited to these aspects unless otherwise specified in the following description to the effect that the present invention is particularly limited. Furthermore, in each drawing, similar components are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0019] FIG. 1 is a perspective view showing a gas engine according to an embodiment of the present invention. FIG. 2 is a perspective view of the intake manifold of this embodiment as viewed from the intake main body side. FIG. 3 is a perspective view of the intake manifold of this embodiment as viewed from the intake pipe side.

[0020] The gas engine 2 according to this embodiment is an internal combustion engine, i.e., a gas engine, that runs on gaseous fuel such as hydrogen gas, natural gas, LPG, or biogas. The gas engine 2 shown in FIG. 1 is a four-cylinder engine that is mounted on industrial machinery such as construction machinery or agricultural machinery. For convenience of explanation, the following description will use a gas engine that runs on hydrogen gas as an example. However, the gas engine according to this embodiment is not limited to gas engines that run on hydrogen gas.

[0021] As shown in FIG. 1, the gas engine 2 includes a cylinder block 3, a cylinder head 4, a head cover 5, an oil pan 6, and an intake manifold 8. The cylinder block 3 has a crankcase 31 formed in the lower part and a cylinder (i.e., cylinder: not shown) formed in the upper part. As described above, the gas engine 2 shown in FIG. 1 has four cylinders. The cylinder head 4 is attached to the upper part of the cylinder block 3. The head cover 5 is attached to the upper part of the cylinder head 4. The oil pan 6 is attached to the lower part of the cylinder block 3 (specifically, the lower part of the crankcase 31).

[0022] The gas engine 2 includes a throttle valve 91 (e.g., an electronically controlled throttle valve) and a fuel rail 92. As shown in FIG. 3, the gas engine 2 further includes an injector 7. As indicated by arrow A1 in FIGS. 1 to 3, air (i.e., intake air) taken in through an air cleaner (not shown) provided in an intake system is supplied to the throttle valve 91. The throttle valve 91 is provided in the intake system and opens and closes to control the amount of intake air supplied to the intake manifold 8. As indicated by arrow A2 in FIGS. 1 to 3, hydrogen gas as gaseous fuel is supplied from a regulator to the fuel rail 92. The hydrogen gas supplied to the fuel rail 92 is then supplied to the injector 7. The injector 7 is attached to an intake pipe 82 and injects hydrogen gas as gaseous fuel into the intake system, i.e., the intake pipe 82.

[0023] The intake manifold 8 is provided downstream of a throttle valve 91 in the intake system and is attached to a side portion of the cylinder head 4. As shown in FIGS. 2 and 3, the intake manifold 8 has an intake main body 81 and multiple intake pipes 82. The intake main body 81 is connected to the throttle valve 91 via a connecting member 93, and temporarily stores the intake air that has passed through the throttle valve 91 and then directs the intake air to the multiple intake pipes 82. As shown in FIG. 3, the multiple intake pipes 82 include a first intake pipe 821, a second intake pipe 822, a third intake pipe 823, and a fourth intake pipe 824. That is, the intake manifold 8 according to this embodiment has the multiple intake pipes 82, which are the first intake pipe 821, the second intake pipe 822, the third intake pipe 823, and the fourth intake pipe 824.

[0024] The first intake pipe 821 is connected to a first cylinder (not shown) formed in the cylinder block 3 via an intake port (not shown) formed in the cylinder head 4. As shown in FIG. 3, the first intake pipe 821 of this embodiment branches near the connection between the intake manifold 8 and the cylinder head 4. Therefore, as shown by arrows A11 and A12 in FIG. 3, the mixture of intake air supplied from the intake body 81 to the first intake pipe 821 and hydrogen gas injected by the injector 7 is guided to the two intake ports and supplied to the first cylinder. In other words, the gas engine 2 shown in FIGS. 1 to 3 has two intake valves per cylinder. However, the number of intake valves provided per cylinder in the gas engine 2 according to this embodiment is not limited to two.

[0025] The second intake pipe 822 is connected to a second cylinder (not shown) formed in the cylinder block 3 via an intake port (not shown) formed in the cylinder head 4. As shown in Fig. 3, the second intake pipe 822 of this embodiment branches off near the connection between the intake manifold 8 and the cylinder head 4. Therefore, as indicated by arrows A13 and A14 in Fig. 3, the mixture of intake air supplied from the intake main body 81 to the second intake pipe 822 and hydrogen gas injected by the injector 7 is guided to the two intake ports and supplied to the second cylinder.

[0026] The third intake pipe 823 is connected to a third cylinder (not shown) formed in the cylinder block 3 via an intake port (not shown) formed in the cylinder head 4. As shown in Fig. 3, the third intake pipe 823 of this embodiment branches off near the connection between the intake manifold 8 and the cylinder head 4. Therefore, as indicated by arrows A15 and A16 in Fig. 3, the mixture of intake air supplied from the intake body 81 to the third intake pipe 823 and hydrogen gas injected by the injector 7 is guided to the two intake ports and supplied to the third cylinder.

[0027] The fourth intake pipe 824 is connected to a fourth cylinder (not shown) formed in the cylinder block 3 via an intake port (not shown) formed in the cylinder head 4. As shown in Fig. 3, the fourth intake pipe 824 of this embodiment branches near the connection between the intake manifold 8 and the cylinder head 4. Therefore, as shown by arrows A17 and A18 in Fig. 3, the mixture of intake air supplied from the intake main body 81 to the fourth intake pipe 824 and hydrogen gas injected by the injector 7 is guided to the two intake ports and supplied to the fourth cylinder.

[0028] In this way, the intake manifold 8 guides the mixture containing hydrogen gas as gaseous fuel and intake air toward the cylinders of the cylinder block 3. Specifically, the intake manifold 8 guides the mixture containing hydrogen gas and intake air to the intake ports of the cylinder head 4. Then, the cylinder head 4 guides the mixture supplied from the intake manifold 8 to the cylinders of the cylinder block 3 through the intake ports.

[0029] In engines that run on gaseous fuel (especially hydrogen gas), the mixture of gaseous fuel and intake air can sometimes cause abnormal combustion (backfire) near the combustion chamber of the gas engine when the engine is started or running. When a backfire occurs, there is a risk of flames flowing back into the intake system. For example, a flame generated by ignition of gaseous fuel remaining in the intake port of the cylinder head may flow back upstream in the intake system. Therefore, one solution is to install a backfire prevention device to suppress the backflow of flames. However, depending on the installation location of the backfire prevention device, there is a risk of pressure loss occurring in the intake system of the gas engine.

[0030] In contrast, the flashback prevention device of this embodiment is provided downstream of the throttle valve 91 in the intake system, and prevents flames generated by ignition of hydrogen gas remaining in the intake port of the cylinder head 4 from flowing back upstream in the intake system. The flashback prevention device of this embodiment will be described in detail below with reference to the drawings.

[0031] FIG. 4 is an exploded perspective view showing a first example of a flashback prevention device according to the present embodiment. For ease of explanation, FIG. 4 shows the connecting member 93 exploded from the intake manifold 8.

[0032] As shown in Fig. 4, in this example, the gas engine 2 is equipped with a flashback prevention device 83. The flashback prevention device 83 in this example is, for example, a corrugated plate type (crimp ribbon type) flame arrester, and is provided between the throttle valve 91 and the intake main body 81. Specifically, as shown in Fig. 4, one flashback prevention device 83 is installed in the upstream part (i.e., the inlet part) of the intake main body 81, and is fixed in a state sandwiched between the upstream part of the intake main body 81 and the connecting member 93.

[0033] In this specific example, it is possible to install one relatively large flashback prevention device 83 in a location in the intake system with a relatively large flow path area. Therefore, it is possible to sufficiently suppress pressure loss in the intake system and prevent flames from flowing back into the intake system when a backfire occurs. Also, compared to the second and third specific examples described below, the pressure loss caused by the flashback prevention device 83 is smaller. Furthermore, because only one flashback prevention device 83 needs to be installed, the structure near the flashback prevention device 83 can be simplified compared to the second and third specific examples described below.

[0034] FIG. 5 is an exploded perspective view showing a second example of the flashback prevention device of the present embodiment. For ease of explanation, FIG. 5 shows the intake body 81 disassembled from the plurality of intake pipes 82.

[0035] As shown in Fig. 5, in this example, the gas engine 2 is equipped with a flashback prevention device 83A. The flashback prevention device 83A in this example is, for example, a corrugated plate type (crimp ribbon type) flame arrester, and is provided between the intake main body 81 and the injector 7 (see Fig. 3). Specifically, as shown in Fig. 5, four flashback prevention devices 83A are installed at the upstream portions (i.e., inlet portions) of the multiple intake pipes 82, and are fixed in a state sandwiched between the downstream portion of the intake main body 81 and the upstream portions of the multiple intake pipes 82.

[0036] In this example, the backfire prevention device 83A is provided between the intake body 81 and the injector 7 (specifically, upstream of the multiple intake pipes 82), which reduces pressure loss in the intake system and more reliably prevents flames generated by ignition of hydrogen gas remaining in the intake port of the cylinder head 4 from flowing back toward the upstream of the intake system. Furthermore, compared to the first example described above, the range of backflow of flames can be narrowed, ensuring higher safety.

[0037] 5, the intake main body 81 is provided as a separate body from the multiple intake pipes 82 and is fastened to the multiple intake pipes 82 with fastening members 85 such as bolts. The intake main body 81 can be removed from the multiple intake pipes 82 by removing the fastening members 85. Therefore, by removing the intake main body 81 from the multiple intake pipes 82, an operator can easily install the flashback prevention device 83A between the intake main body 81 and the injector 7 and remove the flashback prevention device 83A from between the intake main body 81 and the injector 7.

[0038] FIG. 6 is a perspective view showing a third example of the flashback prevention device of this embodiment. As shown in FIG. 6, in this example, the gas engine 2 is equipped with a flashback prevention device 83B. The flashback prevention device 83B in this example is, for example, a corrugated plate (crimp ribbon) flame arrester, and the flashback prevention device 83B is provided between the injector 7 and the cylinder head 4. Specifically, as shown in FIG. 6, eight flashback prevention devices 83B are installed at the downstream portions (i.e., outlet portions) of the multiple intake pipes 82. The flashback prevention devices 83B may be fixed in a state sandwiched between the downstream portions of the multiple intake pipes 82 and the cylinder head 4.

[0039] In this example, the flashback prevention device 83B is provided between the injector 7 and the cylinder head 4 (specifically, downstream of the plurality of intake pipes 82), which reduces pressure loss in the intake system and more reliably prevents the flame in the combustion chamber from igniting the hydrogen gas remaining in the intake port of the cylinder head 4, and more reliably prevents the flame from flowing back upstream in the intake system. Furthermore, higher safety can be ensured compared to the first and second examples described above.

[0040] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. The configurations of the above embodiments can be partially omitted or arbitrarily combined in a different manner from the above. [Explanation of symbols]

[0041] 2: Gas engine, 3: Cylinder block, 4: Cylinder head, 5: Head cover, 6: Oil pan, 7: Injector, 8: Intake manifold, 31: Crankcase, 81: Intake body, 82: Intake pipe, 83: Backfire prevention device, 83A: Backfire prevention device, 83B: Backfire prevention device, 85: Fastening member, 91: Throttle valve, 92: Fuel rail, 93: Connecting member, 821: First intake pipe, 822: Second intake pipe, 823: Third intake pipe, 824: Fourth intake pipe

Claims

1. A gas engine that runs on gaseous fuel, a throttle valve provided in the intake system that opens and closes to control the amount of intake air; an intake manifold provided downstream of the throttle valve in the intake system for directing a mixture containing the gaseous fuel and intake air toward the cylinders of a cylinder block; an injector attached to the intake manifold for injecting the gaseous fuel into the intake system; a cylinder head assembled to the intake manifold, having an intake port, and directing the air-fuel mixture supplied from the intake manifold through the intake port to the cylinder; a backfire prevention device that is provided downstream of the throttle valve in the intake system and that prevents a flame generated by ignition of the gaseous fuel remaining in the intake port from flowing back toward the upstream of the intake system; Equipped with The intake manifold is an intake body that temporarily stores the intake air that has passed through the throttle valve; a plurality of intake pipes connected to the intake body and distributing the intake air guided from the intake body to the plurality of cylinders; and the injector is attached to the intake pipe and injects the gaseous fuel into the intake pipe; The gas engine is characterized in that the backfire prevention device is installed upstream of the intake pipe between the intake body and the injector.

2. A gas engine as described in Claim 1, characterized in that the backfire prevention device is fixed in a state sandwiched between the downstream part of the intake body and the upstream part of the intake pipe.

3. 2. The gas engine according to claim 1, wherein the intake body is provided as a separate body from the intake pipe and is detachable from the intake pipe.

4. A gas engine that runs on gaseous fuel, a throttle valve provided in the intake system that opens and closes to control the amount of intake air; an intake manifold provided downstream of the throttle valve in the intake system for directing a mixture containing the gaseous fuel and intake air toward the cylinders of a cylinder block; an injector attached to the intake manifold for injecting the gaseous fuel into the intake system; a cylinder head assembled to the intake manifold, having an intake port, and directing the air-fuel mixture supplied from the intake manifold through the intake port to the cylinder; a backfire prevention device that is provided downstream of the throttle valve in the intake system and that prevents a flame generated by ignition of the gaseous fuel remaining in the intake port from flowing back toward the upstream of the intake system; Equipped with The intake manifold is an intake body that temporarily stores the intake air that has passed through the throttle valve; a plurality of intake pipes connected to the intake body and distributing the intake air guided from the intake body to the plurality of cylinders; and the injector is attached to the intake pipe and injects the gaseous fuel into the intake pipe; The gas engine is characterized in that the backfire prevention device is installed downstream of the intake pipe between the injector and the cylinder head.

5. A gas engine as described in Claim 4, characterized in that the backfire prevention device is fixed in a state sandwiched between the downstream portion of the intake pipe and the cylinder head.

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