Gas engine

Abstract

To provide a gas engine which can prevent a leaked fuel gas from catching a fire by a simple constitution.SOLUTION: A gas engine 1 includes: an engine frame 2 including a crank chamber 21 for accommodating a crankshaft 22; a cylinder 3 protruding from the engine frame 2; and a cylinder head 4 attached to the cylinder 3, and including an air supply path 41 and an exhaust path 42. Also, the gas engine 1 includes: a fuel gas valve 51 provided at the air supply pipe 13 connected to the cylinder head 4 or at the cylinder head 4, and controlling the injection of a fuel gas into supply air; a separation cover 8 forming a separation chamber 80 for accommodating the cylinder 3, the cylinder head 4 and the fuel gas valve 51 between the engine frame 2 and itself; and a ventilation fan for sucking air in the separation chamber 80.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a gas engine that uses fuel gas as fuel.

Background Art

[0002] Conventionally, gas engines that are four-cycle reciprocating engines have been known. Such a gas engine includes a structure including a crankcase that houses a crankshaft, a plurality of cylinders protruding from the structure, and a plurality of cylinder heads respectively attached to those cylinders. An air intake passage and an exhaust passage are formed in each cylinder head.

[0003] For example, FIG. 3 of Patent Document 1 describes a gas engine in which a fuel gas valve is provided in a cylinder head. The fuel gas valve controls the injection of fuel gas into the intake air.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when the fuel gas valve is exposed, as a countermeasure when fuel gas leaks from the fuel gas valve, it is necessary to take a countermeasure to prevent ignition of the leaked fuel gas. For example, it is conceivable to ventilate the engine room where the gas engine is disposed more than a normal building. On the other hand, it is desired to prevent ignition of the leaked fuel gas with a simpler configuration.

[0006] Therefore, an object of the present disclosure is to provide a gas engine that can prevent ignition of leaked fuel gas with a simple configuration.

Means for Solving the Problems

[0007] The present disclosure provides a gas engine including a structure including a crank chamber for accommodating a crankshaft, a cylinder protruding from the structure, a cylinder head including an air intake passage and an exhaust passage attached to the cylinder, an intake pipe connected to the cylinder head or a fuel gas valve provided in the cylinder head for controlling injection of fuel gas into the intake air, an isolation cover forming an isolation chamber for accommodating the cylinder, the cylinder head, and the fuel gas valve between the structure, and a ventilation fan for sucking air in the isolation chamber.

Advantages of the Invention

[0008] According to the present disclosure, there is provided a gas engine that can prevent ignition of leaked fuel gas with a simple configuration.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0010] FIGS. 1 and 2 show a gas engine 1 according to an embodiment. This gas engine 1 uses a fuel gas such as city gas, natural gas, biogas, or hydrogen gas as fuel.

[0011]

[0012] ​A plurality of cylinders 3 each have a plurality of cylinder heads 4 attached thereto. A piston 24 is disposed within each cylinder 3. The piston 24 is connected to the crankshaft 22 by a rod 23. A combustion chamber 10 is formed between the piston 24 and the cylinder head 4.

[0013] Each cylinder head 4 has an intake passage 41 and an exhaust passage 42 formed therein. In FIG. 1, for the sake of schematically showing the structure of the gas engine 1, the intake passage 41 and the exhaust passage 42 are depicted as extending in opposite directions from the combustion chamber 10, but in actuality, as shown in FIG. 2, the intake passage 41 and the exhaust passage 42 extend in the same direction from the combustion chamber 10.

[0014] That is, in the present embodiment, an intake manifold 15 and an exhaust manifold, which will be described later, are arranged on the same side with respect to the cylinder bank. However, the intake manifold 15 and the exhaust manifold may be arranged on opposite sides with respect to the cylinder bank, and the intake passage 41 and the exhaust passage 42 may extend in opposite directions from the combustion chamber 10.

[0015] Each cylinder head 4 is provided with an intake valve 11 and an exhaust valve 12. The intake valve 11 opens and closes the opening of the intake passage 41 with respect to the combustion chamber 10, and the exhaust valve 12 opens and closes the opening of the exhaust passage 42 with respect to the combustion chamber 10.

[0016] Further, an intake pipe 13 and an exhaust pipe 14 are connected to each cylinder head 4. The gas engine 1 includes an intake manifold 15 extending in the arrangement direction of the cylinders 3, and each intake pipe 13 communicates the intake manifold 15 with the corresponding intake passage 41. Similarly, each exhaust pipe 14 communicates the exhaust manifold extending in the arrangement direction of the cylinders 3 with the corresponding exhaust passage 42.

[0017] A cylinder head cover 45 is attached to each cylinder head 4. On the side opposite to the cylinder 3 with the cylinder head 4 interposed therebetween, devices such as a drive mechanism for driving the intake valve 11 and the exhaust valve 12 are arranged, and the cylinder head cover 45 covers the devices.

[0018] Furthermore, the gas engine 1 includes a main fuel gas valve 51, an ignition device 7, and an auxiliary fuel gas valve 61 for each cylinder 3. The gas engine 1 also includes a first fuel gas supply pipe 53 and a second fuel gas supply pipe 63 that extend in the arrangement direction of the cylinders 3. Each main fuel gas valve 51 is connected to the first fuel gas supply pipe 53 by a first branch pipe 52, and each auxiliary fuel gas valve 61 is connected to the second fuel gas supply pipe 63 by a second branch pipe 62.

[0019] In this embodiment, the main fuel gas valve 51 is provided in the intake pipe 13. Also, in this embodiment, the fuel injection nozzle of the main fuel gas valve 51 extends into the intake passage 41 of the cylinder head 4, and the main fuel gas valve 51 injects fuel gas into the intake air in the intake passage 41. The main fuel gas valve 51 controls the injection of fuel gas into the intake air by being electrically controlled.

[0020] However, the tip of the fuel injection nozzle of the main fuel gas valve 51 may be located in the intake pipe 13, and the main fuel gas valve 51 may inject fuel gas into the intake air in the intake pipe 13. Also, the main fuel gas valve 51 may be provided in the cylinder head 4. In this case, the main fuel gas valve 51 may directly inject fuel gas into the intake air in the combustion chamber 10.

[0021] The ignition device 7 ignites the air-fuel mixture of the fuel gas injected from the main fuel gas valve 51 and the intake air in the combustion chamber 10. In this embodiment, the ignition device 7 includes a sub-chamber 70 and a spark plug 73. The sub-chamber 70 communicates with the combustion chamber 10 through injection holes.

[0022] In this embodiment, the combustion of the air-fuel mixture in the combustion chamber 10 is lean burn. The ignition device 7 ignites the air-fuel mixture of fuel gas (injected into the sub-chamber 70 via the auxiliary fuel gas valve 61) and air in the sub-chamber 70 by the spark plug 73, and ignites the lean air-fuel mixture in the combustion chamber 10 by the flame from the injection holes.

[0023] The ignition device 7 extends through the cylinder head cover 45 from the cylinder head 4 and an isolation cover 8 described later. Specifically, the ignition device 7 includes a rod-shaped sub-chamber holder 72 that extends from inside the cylinder head 4 to outside the isolation cover 8 along the extension line of the center line of the cylinder 3, and a surrounding portion 71 that surrounds the sub-chamber 70 together with the tip surface of the sub-chamber holder 72. A part of the surrounding portion 71 protrudes into the combustion chamber 10, and the above-described injection holes are formed in this protruding portion.

[0024] A through hole extending in the axial direction of the sub-chamber holder 72 is formed in the sub-chamber holder 72. An ignition plug 73 is disposed in this through hole so as to partially protrude into the sub-chamber 70.

[0025] The sub-fuel gas valve 61 is provided in the cylinder head 4. The sub-fuel gas valve 61 may be attached to the upper surface of the cylinder head 4 as shown in FIG. 1, or may be attached to the side surface of the cylinder head 4 as shown in FIG. 2.

[0026] The sub-fuel gas valve 61 is connected to the sub-chamber 70 via a fuel supply passage 60 formed in the cylinder head 4 and the sub-chamber holder 72. The sub-fuel gas valve 61 controls the injection of fuel gas into the sub-chamber 70 by being electrically controlled. Note that the sub-fuel gas valve 61 may directly inject fuel gas into the sub-chamber 70.

[0027] Furthermore, in the present embodiment, an isolation cover 8 that forms an isolation chamber 80 between the isolation cover 8 and the structure 2 is employed. The isolation chamber 80 houses all the cylinders 3, all the cylinder head covers 45, all the main fuel gas valves 51, and all the sub-fuel gas valves 61.

[0028] The isolation chamber 80 is a room for holding the leaked fuel gas when the fuel gas leaks from the main fuel gas valve 51 or the sub-fuel gas valve 61. For this reason, the main fuel gas valve 51 and the sub-fuel gas valve 61 are explosion-proof products.

[0029] The isolation chamber 80 includes a first side wall 81 and a second side wall 82 that face each other across the cylinder 3 in a direction orthogonal to the arrangement direction of the cylinders 3, a third side wall 83 and a fourth side wall 84 that face each other across the cylinder 3 in the arrangement direction of the cylinders 3, and a ceiling wall 85 that covers the space surrounded by the first to fourth side walls 81 to 84 from above.

[0030] The first to fourth side walls 81 to 84 rise along the cylinder 3 from the framework 2. The above-described air supply pipe 13 and exhaust pipe 14 penetrate through the second side wall 82 located near the air supply manifold 15.

[0031] In this embodiment, a pressure sensor 31 for detecting the pressure in the combustion chamber 10 is provided on each cylinder head 4. In the illustrated example, the pressure sensor 31 extends radially outward from the combustion chamber 10 along the cylinder 3 and protrudes from the side surface of the cylinder head 4. However, the extending direction of the pressure sensor 31 can be appropriately changed. Further, the pressure sensor 31 does not necessarily have to be provided on each cylinder head 4, and may be provided on each cylinder 3 so as to protrude from the cylinder 3.

[0032] A tubular portion 86 into which the pressure sensor 31 is inserted is provided on the first side wall 81. The tubular portion 86 extends from the first side wall 81 to the vicinity of the cylinder head 4. The tubular portion 86 forms a hole in the first side wall 81 to expose the pressure sensor 31. For this reason, a non-explosion-proof product can be used as the pressure sensor 31. Note that the length of the tubular portion 86 is not particularly limited, and may be shorter or longer than the inner diameter of the tubular portion 86. Further, depending on the orientation of the pressure sensor 31, the tubular portion 86 may be provided on the ceiling wall 85 to form a hole for exposing the pressure sensor 31 in the ceiling wall 85.

[0033] An ignition coil 75 is disposed outside the isolation chamber 80. The spark plug 73 of the ignition device 7 is connected to the ignition coil 75 by a cable 74. For this reason, a non-explosion-proof product can be used for the ignition coil 75.

[0034] An isolation chamber 80 is connected to a first ventilation pipe 90 and a second ventilation pipe 91. In the present embodiment, the first ventilation pipe 90 and the second ventilation pipe 91 are arranged on both sides of the cylinder 3 in the arrangement direction of the cylinder 3. That is, the first ventilation pipe 90 is connected to the third side wall 83, and the second ventilation pipe 91 is connected to the fourth side wall 84. Air is taken into the isolation chamber 80 through the first ventilation pipe 90, and the air in the isolation chamber 80 is discharged to a predetermined location (for example, outside the engine room where the gas engine 1 is arranged) through the second ventilation pipe 91.

[0035] The second ventilation pipe 91 is provided with a ventilation fan 92 for sucking the air in the isolation chamber 80. Further, the second ventilation pipe 91 is provided with a detector 93 for detecting whether the concentration of the fuel gas in the second ventilation pipe 91 exceeds a threshold value. In the illustrated example, the detector 93 is located upstream of the ventilation fan 92, but it may be located downstream of the ventilation fan 92. Further, the detector 93 may be provided on, for example, the isolation cover 8 to detect whether the concentration of the fuel gas in the isolation chamber 80 exceeds a threshold value.

[0036] The detector 93 may be a single sensor that emits a signal when the concentration of the fuel gas exceeds the threshold value, or may be composed of a concentration sensor for detecting the concentration of the fuel gas and a determination device for determining whether the concentration detected by the concentration sensor exceeds the threshold value.

[0037] In the gas engine 1 having the configuration described above, even if the fuel gas leaks from the main fuel gas valve 51 or the sub-fuel gas valve 61, the fuel gas is kept in the isolation chamber 80 and is discharged from the isolation chamber 80 by the ventilation fan 92. Therefore, ignition of the leaked fuel gas can be prevented with a simple configuration. Moreover, non-explosion-proof products can be used for the electrical equipment arranged outside the isolation chamber 80.

[0038] Further, in the present embodiment, since the detector 93 is employed, it is possible to monitor whether the fuel gas has leaked.

[0039] (Modification example) The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0040] For example, the ignition device 7 does not necessarily have to include the auxiliary chamber 70 and the spark plug 73, and may be configured to inject pilot fuel into the combustion chamber 10 to cause the pilot fuel to auto-ignite. In this case, the auxiliary fuel gas valve 61 is unnecessary.

[0041] However, when the gas engine 1 includes the auxiliary chamber type ignition device 7 as in the above embodiment, if the auxiliary fuel gas valve 61 is housed in the isolation chamber 80 together with the main fuel gas valve 51, it is possible to cope not only with the leakage of fuel gas from the main fuel gas valve 51 but also with the leakage of fuel gas from the auxiliary fuel gas valve 61.

[0042] (Summary) The present disclosure provides a gas engine including a structure including a crankcase that houses a crankshaft, a cylinder protruding from the structure, a cylinder head attached to the cylinder and including an intake passage and an exhaust passage, a fuel gas valve that is connected to the cylinder head or provided in the cylinder head and controls injection of fuel gas into the intake air, an isolation cover that forms an isolation chamber between the structure and houses the cylinder, the cylinder head, and the fuel gas valve, and a ventilation fan that sucks air in the isolation chamber.

[0043] According to the above configuration, even if fuel gas leaks from the fuel gas valve, the fuel gas is kept in the isolation chamber and discharged from the isolation chamber by the ventilation fan. Therefore, it is possible to prevent ignition of the leaked fuel gas with a simple configuration. Moreover, non-explosion-proof products can be used for electrical equipment arranged outside the isolation chamber.

[0044] The above gas engine may further include a ventilation pipe connected to the isolation chamber and provided with the ventilation fan, and a detector that detects whether or not the concentration of the fuel gas in the isolation chamber or in the ventilation pipe exceeds a threshold value. According to this configuration, it is possible to monitor whether or not fuel gas has leaked.

[0045] The above gas engine further includes a pressure sensor protruding from the cylinder head or the cylinder for detecting the pressure in the combustion chamber formed between the piston disposed in the cylinder and the cylinder head, and the isolation cover may include a tubular portion forming a hole for exposing the pressure sensor. According to this configuration, a non-explosion-proof product can be used as the pressure sensor.

[0046] The above gas engine further includes a cylinder head cover housed in the isolation chamber, the cylinder head cover covering the equipment disposed on the side opposite to the cylinder with the cylinder head interposed therebetween, and an ignition device including an ignition plug for igniting the air-fuel mixture of the fuel gas and the intake air in the combustion chamber formed between the piston disposed in the cylinder and the cylinder head, and an ignition device extending through the cylinder head cover and the isolation cover from the cylinder head. According to this configuration, since the ignition coil connected to the ignition device is disposed outside the isolation chamber, a non-explosion-proof product can be used for the ignition coil.

[0047] The ignition device includes a sub-chamber communicating with the combustion chamber through a nozzle hole, and the ignition plug ignites the air-fuel mixture in the sub-chamber to ignite the air-fuel mixture in the combustion chamber by the flame from the nozzle hole. The fuel gas valve is a main fuel gas valve. The above gas engine further includes a sub-fuel gas valve provided on the cylinder head for controlling the injection of the fuel gas into the sub-chamber, and the sub-fuel gas valve may be housed in the isolation chamber. According to this configuration, when the gas engine includes a sub-chamber type ignition device, it is possible to cope with the leakage of the fuel gas from the sub-fuel gas valve.

Description of Reference Numerals

[0048] 1 Gas engine 10 Combustion chamber 13 Intake pipe 14 Exhaust pipe 2 Structure 21 Crank chamber 22 Crankshaft 24 Piston 3 Cylinder 31 Pressure Sensor 4 Cylinder Head 41 Intake Passage 42 Exhaust Passage 45 Cylinder Head Cover 51 Main Fuel Gas Valve 61 Sub-Fuel Gas Valve 7 Ignition Device 70 Auxiliary Chamber 72 Auxiliary Chamber Holder 73 Spark Plug 8 Isolation Cover 80 Isolation Chamber 86 Tubular Portion 90, 91 Ventilation Pipe 92 Ventilation Fan 93 Detector

Claims

1. A structure including a crank chamber for accommodating a crankshaft, a cylinder protruding from the structure, a cylinder head attached to the cylinder and including an air intake passage and an exhaust passage, a fuel gas valve that is connected to the cylinder head or provided on the cylinder head and controls the injection of fuel gas into the intake air, an isolation cover that forms an isolation chamber between the structure and accommodates the cylinder, the cylinder head, and the fuel gas valve, a ventilation fan that sucks air in the isolation chamber, A gas engine comprising:

2. A ventilation pipe connected to the isolation chamber and provided with the ventilation fan, A detector that detects whether the concentration of the fuel gas in the isolation chamber or in the ventilation pipe exceeds a threshold value, The gas engine according to claim 1, further comprising:

3. Further comprising a pressure sensor protruding from the cylinder head or the cylinder that detects the pressure in the combustion chamber formed between the piston disposed in the cylinder and the cylinder head, The isolation cover includes a tubular portion that forms a hole for exposing the pressure sensor. The gas engine according to claim 1 or 2.

4. A cylinder head cover accommodated in the isolation chamber, the cylinder head cover covering equipment disposed on the opposite side of the cylinder with the cylinder head interposed therebetween, An ignition device including an ignition plug that ignites a mixture of fuel gas and intake air in the combustion chamber formed between the piston disposed in the cylinder and the cylinder head, and the ignition device extends through the cylinder head cover and the isolation cover from the cylinder head. The gas engine according to any one of claims 1 to 3, further comprising:

5. The ignition device includes a sub-chamber communicating with the combustion chamber through an injection hole, and the ignition plug ignites a mixture of fuel gas and air in the sub-chamber, thereby igniting the mixture in the combustion chamber by the flame from the injection hole. The fuel gas valve is a main fuel gas valve, Further comprising a sub-fuel gas valve provided on the cylinder head and controlling the injection of fuel gas into the sub-chamber, The sub-fuel gas valve is accommodated in the isolation chamber. The gas engine according to claim 4.

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