JP5872335B2 - Sub-chamber gas engine - Google Patents

Description

  The present invention relates to a sub-chamber gas engine having a pressure regulating valve for adjusting a gas pressure applied to the sub-chamber in a path for supplying fuel gas to the sub-chamber.

  Patent Document 1 discloses a gas engine that appropriately controls the fuel supply pressure to the sub chamber, with the object of being able to stably operate the engine in an optimal state at all times. This gas engine includes a mechanical regulator and an electric variable throttle valve in a path for supplying fuel gas to the sub chamber. The variable throttle valve is downstream of the mechanical regulator. The mechanical regulator adjusts the pressure of the fuel gas supplied to the sub chamber with reference to the intake pressure. The variable throttle valve controls the gas pressure based on the rotation speed and the intake pressure.

  In a large gas engine, the inner diameter of the path for supplying the fuel gas to the sub chamber is large. The pressure regulating valve (variable throttle valve) arranged in the gas path of the sub chamber is also enlarged, and the moving time of the valve body is also increased. For this reason, as described in Patent Document 1, changing the gas pressure in the sub chamber by changing the opening of the pressure regulating valve (variable throttle valve) means that the gas pressure is adjusted from the occurrence of load fluctuations. Increase the time to complete. That is, changing the opening degree by the pressure regulating valve decreases the responsiveness to the load fluctuation, and conversely, the fluctuation of the rotational speed cannot be satisfactorily suppressed.

  In the case of an engine that is normally controlled to maintain a single target rotational speed, such as an engine used for power generation, the gas pressure in the sub chamber needs to be adjusted to optimize the operation. Is limited. In such an engine, for example, it is required to be able to suppress fluctuations in the number of revolutions at the time of start-up and load application.

  For this reason, conventionally, a large gas engine is operated in a state where the opening of the pressure regulating valve is always kept at a predetermined opening. For example, an opening degree that enhances responsiveness at the time of starting is selected as the predetermined opening degree. Here, the opening degree indicates the cross sectional area of the gas in the gas path.

Japanese Patent No. 3104422

  As described in the cited document 1, the optimum gas pressure in the sub chamber differs depending on the operation state. For example, the optimum gas pressure in the sub chamber may be different during start-up, acceleration, steady operation, and load application. When the opening degree of the pressure regulating valve is kept constant as in the conventional example described above, the optimality of operation is impaired. Cited Document 1 discloses changing the opening of the pressure regulating valve in accordance with the operating state. However, the change in the opening of the pressure regulating valve delays the change of the gas pressure with respect to the occurrence of a new operating state, and therefore the optimality of the operation is impaired as in the case where the opening of the pressure regulating valve is kept constant. End up.

  Therefore, the present invention provides a sub-chamber gas engine that can change the gas pressure applied to the sub-chamber without causing a delay with respect to the occurrence of a new operating state.

  A sub-chamber gas engine according to the present invention is a sub-chamber gas engine having a main pressure regulating valve for adjusting a gas pressure applied to the sub-chamber in a path for supplying fuel gas to the sub-chamber, and is branched from the path and An OFF path that joins the path, an on-off valve that is arranged on the OFF path, an ON path that branches off from the path and joins the path, and an orifice or a pressure regulating valve that is arranged on the ON path. And a pressure regulating unit arranged in the path between the main pressure regulating valve and the sub chamber, a state detector for detecting occurrence of a specific operation state, and detection of occurrence of the specific operation state A control device that temporarily closes the on-off valve, and the on-off valve discretely changes the opening of the OFF path to open or closed.

  In the gas engine, the specific operation state is a load application, and the state detector is a load application detector that detects the occurrence of the load application.

  In the gas engine, the rotation speed of the gas engine is controlled so as to coincide with a set target rotation speed, and the load application detector has the rotation speed decreased by a predetermined width or more than the target rotation speed. In such a case, a decrease in the rotational speed is detected.

  The gas engine includes an output detector that detects an output of the gas engine, and the load input detector has a load factor within a range of an upper limit and a lower limit load factor and is loaded when the rotational speed is reduced. Detect outbreaks.

  The gas engine according to the present invention can change the gas pressure applied to the sub chamber without causing a delay with respect to the occurrence of a new operation state.

FIG. 1 is a diagram illustrating a configuration of a gas engine. FIG. 2 is a diagram illustrating a configuration of the power supply system. FIG. 3 is a diagram showing the change over time in the rotational speed, opening and closing of the first original valve, opening and closing of the second original valve, and opening and closing of the on-off valve. FIG. 4 is a diagram showing a determination condition for determining opening / closing of the on-off valve. FIG. 5 is a diagram showing the configuration of the gas engine.

(Configuration of the first embodiment)
With reference to FIGS. 1-4, the gas engine 1 which concerns on 1st Embodiment is demonstrated.

  FIG. 1 is a diagram showing a configuration of the gas engine 1. The sub chamber type gas engine 1 includes an engine main body 2, a crankshaft 3, a rotation speed detector 4, a main supply mechanism 5, a sub supply mechanism 6, and a controller 7. The engine body 2 includes a plurality of main chambers (combustion chambers) 2a and sub chambers 2b. The rotational speed detector 4 detects the rotational speed of the crankshaft 3. The main supply mechanism 5 and the sub supply mechanism 6 receive the fuel gas from the external path 200 connected to the gas source, and supply the fuel gas to the main chamber 2a and the sub chamber 2b of the engine body 2. The controller 7 controls the main supply mechanism 5 and the sub supply mechanism 6.

  The sub supply mechanism 6 includes a main path 8, a plurality of branch paths 9, a first original valve 10, a second original valve 11, a main pressure regulating valve 12, a pressure regulating unit 13, and a pressure detector 14. The external path 200 described above is connected to the starting end 8 a of the main path 8. The fuel gas flows from the start end 8a toward the branch path 9. The sub supply mechanism 6 arranges the start end 8a, the first main valve 10, the second main valve 11, the main pressure regulating valve 12, the pressure regulating unit 13, the pressure detector 14, and the branch path 9 in this order along the gas flow direction. doing.

  The main path 8 is configured by connecting a plurality of pipes with flange joints 15. This makes it possible to individually take out the first main valve 10, the second main valve 11, the main pressure regulating valve 12, and the pressure regulating unit 13 from the main path 8. The plurality of branch paths 9 branch from the end of the main path 8. Each branch path 9 is connected to each sub chamber 2 b of the engine body 2. The first original valve 10 and the second original valve 11 are open / close valves, and discretely change the opening of the main path 8 to open or closed. The main pressure regulating valve 12 is a flow rate adjusting valve and can continuously change the opening degree of the main path 8. The main pressure regulating valve 12 is a means for adjusting the opening degree in the sub chamber 2b. The pressure detector 14 detects the gas pressure in the main path 8. The gas pressure in each sub chamber 2 b is equal to the gas pressure detected by the pressure detector 14.

  The pressure adjustment unit 13 includes an OFF path 16, an on-off valve 17, an ON path 18, and an orifice 19. The OFF path 16 branches from the main path 8 and joins the main path 8. The on-off valve 17 is disposed on the OFF path 16. The on-off valve 17 is an electromagnetic on-off valve, and discretely changes the opening degree of the OFF path 16 (main path 8) to open or closed. In the present embodiment, the on-off valve 17 is a solenoid valve and instantaneously switches between opening and closing. The ON path 18 branches from the main path 8 and merges with the main path 8. The orifice 19 is disposed on the ON path 18. The opening degree of the orifice 19 is set smaller than the opening degree of the ON path 18 and the OFF path 16. The opening of the OFF path 16 is the same as the opening of the main path 8. For this reason, the orifice 19 makes the opening degree of the ON path 18 smaller than the opening degree of the OFF path 16 (main path 8).

  The main supply mechanism 5 has a configuration for supplying the air-fuel mixture to the main chamber 2a. The main supply mechanism 5 includes an intake passage 20, a gas passage 21, a fuel injection device 26, a throttle valve 22, a first original valve 23, a second original valve 24, and a pressure regulating valve 25. The intake passage 20 connects the intake port opened to the outside air and the main chamber 2a. The gas path 21 is connected to the external path 200 described above, and merges with the intake path 20 at the merge point 20a. A fuel injection device 26 is provided upstream of the joining location 20 a of the gas path 21. The fuel injection device 26 determines the opening degree of the gas path 21. The fuel injection device 26 is a solenoid valve in this embodiment. The amount of fuel injected into the main chamber 2a is adjusted by controlling the valve opening time of the fuel injection device 26. The throttle valve 22 is disposed on the intake path 20 upstream of the junction 20a. The throttle valve 22 determines the opening degree of the intake passage 20. The first main valve 23, the second main valve 24, and the pressure regulating valve 25 are disposed on the gas path 21. The first original valve 23 and the second original valve 24 are open / close valves, and discretely change the opening of the gas path 21 to open or closed. The pressure regulating valve 25 is a flow rate adjusting valve, and can continuously change the opening degree of the gas path 21. The pressure regulating valve 25 is a means for adjusting the air-fuel ratio in the main chamber 2a.

  FIG. 2 is a diagram illustrating a configuration of the power supply system 100. The power supply system 100 includes the gas engine 1 and the generator 30 described above. The generator 30 converts the rotational power output from the crankshaft 3 into electric power. The power supply system 100 includes a first load 41, a second load 42, a third load 43, and a fourth load 44 as power loads. The first load 41 is an auxiliary machine and provides electric power for driving the gas engine 1 and the generator 30. The power supply system 100 includes a main power line 50, a first power line 51, a second power line 52, a third power line 53, and a fourth power line 54. The main power line 50 extends from the generator 30. The first power line 51, the second power line 52, the third power line 53, and the fourth power line 54 are branched from the main power line 50, and the first load 41, the second load 42, the third load 43, and the fourth power line, respectively. Connected to a load 44. The power supply system 100 includes a main switch 60, a first switch 61, a second switch 62, a third switch 63, and a fourth switch 64 as switches. The main switch 60, the first switch 61, the second switch 62, the third switch 63, and the fourth switch 64 are the main power line 50, the first power line 51, the second power line 52, and the third power line 53, respectively. And on the fourth power line 54.

  The gas engine 1 includes a power detector 31. The power detector 31 detects the power output from the generator 30.

  The control of the on-off valve 17 will be described with reference to FIGS.

  FIG. 3 is a diagram showing changes over time in the rotational speed, opening and closing of the first main valve 10, opening and closing of the second main valve 11, and opening and closing of the on-off valve 17. In general, an acceleration operation is executed from time T0 to time T1, a constant speed operation is executed from time T1 to time T5, and a deceleration operation is executed from time T5 to time T6. In particular, the time from time T0 to time T01 is the start time. Also, loading is performed at times T1, T2, T3, and T4. In this embodiment, the load input indicates that the above-described loads 41, 42, 43, and 44 are connected to the generator 30.

  The operation is stopped before time T0 and after time T6. When the operation is stopped, the intake passage 20 and the gas passage 21 of the main supply passage 5 are closed, and the main passage 8 of the sub supply device 6 is closed. In the main supply path 5, the first main valve 23, the second main valve 24, and the fuel injection device 26 are closed. In the sub supply device 6, the first main valve 10 and the second main valve 1 are closed. For this reason, the rotation speed of the gas engine 1 is 0, and the output power of the generator 30 is also 0. Moreover, all the switches 60-64 are opened, and all the loads 41-44 are disconnected from the generator 30.

  When the start of operation is commanded, the controller 7 first controls the main supply path 5 so that the gas pressure is applied to the main chamber 2a. At time T0, the controller 7 drives the cell motor, and after 5 seconds, opens the first main valve 23 and the second main valve 24, and starts the opening / closing control of the fuel injection device 26. As a result, a gas pressure is generated in the main chamber 2a.

  As the valve opening time of the fuel injection device 26 increases, the rotational speed increases. When the rotational speed reaches the first rotational speed R1 at time T01, the controller 7 opens the on-off valve 17. When the rotational speed reaches the second rotational speed R2 at time T02, the controller 7 opens the first original valve 10 and the second original valve 11. As a result, the main path 8 of the sub supply device 6 is opened. At this time, since the on-off valve 17 is opened, the opening degree of the main path 8 is equal to the opening degree of the main pressure regulating valve 12. In the present embodiment, the first rotation speed R1 and the second rotation speed R2 are 300 rpm and 1100 rpm.

  At time T1, the rotational speed reaches the set target rotational speed RT. During constant speed operation from time T1 to time T5, the controller 7 controls the valve opening time of the fuel injection device 26 so that the rotational speed matches the target rotational speed RT. In the present embodiment, the target rotational speed RT is 1800 rpm.

  At time T1, the controller 7 closes the main switch 60. As a result, electric power is supplied to the first load 41, and a load is applied to the gas engine 1. In the present embodiment, the first load 41 consumes 5% of the rated output of the generator 30. Note that the first switch 61 is already closed before the main switch 60 is closed.

  When the first load 41 is loaded, the rotational speed is decreased. When the controller 7 detects a decrease in the rotational speed, the controller 7 increases the valve opening time of the fuel injection device 26. As a result, the output of the gas engine 1 increases and the rotational speed increases. There is a delay before the rotational speed returns to the target rotational speed RT. For this reason, the rotation speed temporarily decreases.

  When the first load 41 is turned on, the controller 7 controls the gas engine 1 as follows. First, as a result of loading, the rotational speed decreases to the allowable rotational speed RA at time T11. The allowable rotational speed RA is a rotational speed that is smaller than the target rotational speed RT by a predetermined width WR. In the present embodiment, the allowable rotational speed RA and the predetermined width WR are 1780 rpm and 20 rpm. When the rotation speed reaches the allowable rotation speed RA, the controller 7 closes the on-off valve 17 because the load factor is equal to or higher than the lower limit load factor LL. When the on-off valve 17 is closed, the opening of the main path 8 is equal to the opening of the orifice 19. The rotational speed further decreases and then increases, and again reaches the allowable rotational speed RA at time T12. Thereafter, the rotational speed further increases and reaches the target rotational speed RT again. At time T13, the controller 7 opens the on-off valve 17. Time T13 is a time after a predetermined duration WT from time T12. In the present embodiment, the duration WT is 5 s (seconds). That is, the controller 7 keeps the on-off valve 17 in the closed state for the time from time T11 to time T13.

  At time T2, the controller 7 closes the second switch 62. As a result, electric power is supplied to the second load 42 and a load is applied to the gas engine 1. Time T2 is a time later than the time T1 by the first time WT1. In the present embodiment, the first time WT1 is 20 s (seconds). In the present embodiment, the second load 42 consumes 30% of the rated output of the generator 30. For this reason, 35% of the rated output of the generator 30 is consumed by the first load 41 and the second load 42 at time T2.

  By turning on the second load 42, the rotational speed temporarily decreases. The rotational speed decreases to the allowable rotational speed RA at time T21, further decreases and then increases, increases to the allowable rotational speed RA at time T22, and then returns to the target rotational speed RT. The controller 17 keeps the on-off valve 17 in a closed state during a period from time T21 to time T23. Time T23 is a time later by the duration WT than time T22.

  At time T3, the controller 7 closes the third switch 63. As a result, electric power is supplied to the third load 43 and a load is applied to the gas engine 1. The time T3 is a time that is later than the time T2 by the second time WT2. In the present embodiment, the second time WT2 is 30 s (seconds). In the present embodiment, the third load 43 consumes 20% of the rated output of the generator 30. For this reason, 55% of the rated output of the generator 30 is consumed by the loads 41, 42, and 43 at time T3.

  By turning on the third load 43, the rotation speed temporarily decreases. The rotational speed decreases to the allowable rotational speed RA at time T31, further decreases and then increases, increases to the allowable rotational speed RA at time T32, and then returns to the target rotational speed RT. The controller 17 keeps the on-off valve 17 in a closed state during a period from time T31 to time T33. Time T33 is a time later by the duration WT than time T32.

  At time T4, the controller 7 closes the fourth switch 64. As a result, electric power is supplied to the fourth load 44 and the gas engine 1 is loaded. Time T4 is a time after the third time WT3 after time T3. In the present embodiment, the third time WT3 is 20 s (seconds). In the present embodiment, the fourth load 44 consumes 27.5% of the rated output of the generator 30. For this reason, 82.5% of the rated output of the generator 30 is consumed by the load 41-44 at the time T4.

  If the load factor is equal to or higher than the predetermined upper limit load factor LH when occurrence of load application is detected, the controller 7 keeps the on-off valve 17 in an open state without temporarily closing the on-off valve 17. The load factor indicates the ratio of output to the rated output. In the present embodiment, the upper limit load factor LH is 80%. As described above, when the fourth load 44 is loaded, the output power of the generator 30 is 82.5% of the rated output, and the load factor exceeds the upper limit load factor LH (80%). For this reason, the controller 7 keeps the open / close valve 17 in an open state, even though the rotational speed is temporarily reduced by the load application of the fourth load 44.

  Thereafter, even if a new load is applied, the output power of the generator 30 is maintained at 80% or more of the rated output unless the connected load is disconnected. In this case, the controller 7 always keeps the on-off valve 17 open.

  When the stop of the operation is commanded, the controller 7 starts the deceleration operation. At time T5, the controller 7 starts decreasing the valve opening time of the fuel injection device 26, and then closes the first original valve 23, the second original valve 24, the first original valve 10, and the second original valve 11.

  When the gas path 21 and the gas path 8 are closed, the rotational speed is reduced. When the rotational speed decreases to the first rotational speed R1 at time T51, the controller 7 closes the on-off valve 17. At time T6, the rotational speed becomes 0 and the operation is finished.

  FIG. 4 is a diagram showing determination conditions for determining opening / closing of the on-off valve 17. The conditions for determining the opening / closing of the on-off valve 17 are generally explained in the explanation of FIG. 3, but will be explained in more detail in FIG.

This determination condition determines the opening / closing of the on-off valve 17 based on whether the five requirements (1)-(5) are correct or not. Whether the requirement (1) is correct or not is always executed, but whether the requirement (2)-(4) is correct is determined only when the rotational speed is maintained at the target rotational speed (RT).
(1) The average rotational speed is less than the first rotational speed R1 (300 rpm).
(2) The average rotational speed is equal to or lower than the allowable rotational speed RA (1780 rpm).
(3) The time during which the state in which the average rotational speed is greater than the allowable rotational speed RA (1780 rpm) continues is less than the first predetermined time a1 (5 s).
(4) The average load factor is not less than the lower limit load factor LL (2%) and not more than the upper limit load factor LH (80%).
(5) The time during which the average load factor continues to be greater than the upper limit load factor LH (80%) is less than the second predetermined time a2 (5 s).

  The average rotational speed and the average load factor refer to the average value of the rotational speed and the average value of the load factor, respectively, per unit time. In the present embodiment, the first predetermined time a1 and the second predetermined time a2 are each 5 s (seconds).

  When the requirement (1) is positive, the closing of the on-off valve 17 is determined. When the requirement (2) or the requirement (3) is positive and the requirement (4) or the requirement (5) is positive, the closing of the on-off valve 17 is determined. In other cases, opening of the on-off valve 17 is determined.

(Effect of this embodiment)
The gas engine 1 according to the present embodiment has the following effects due to the above-described configuration.

(A) The gas engine 1 according to the present embodiment includes a pressure control unit 13 having an on-off valve 17 and an orifice 19, and a state detector (a rotational speed detector 4 and a controller 7) that detects a specific operation state (loading). ) And a control device (controller 7) for temporarily closing the on-off valve 17. The controller 7 detects a decrease in the rotational speed based on the rotational speed detected by the rotational speed detector 4 and detects the occurrence of a specific operation state (loading). For this reason, the rotation speed detector 4 and the controller 7 constitute a state detector. The on-off valve 17 discretely changes the opening degree of the OFF path 16 to open or closed.

  The gas pressure applied to the sub chamber 2 b is determined by the minimum opening of the main path 8. When the on-off valve 17 is closed, the gas pressure applied to the sub chamber 2 b is determined by the opening degree of the orifice 19. When the on-off valve 17 is opened, the gas pressure applied to the sub chamber 2 b is mainly determined by the opening degree of the OFF path 16. Further, since the opening / closing valve 17 instantaneously (in a very short time) changes the opening degree of the OFF path 16 to open or closed, the gas pressure applied to the main path 8 and the sub chamber 2b is instantaneously changed.

  For this reason, the gas engine 1 which concerns on this embodiment can change the gas pressure applied to the subchamber 2b, without producing a delay with respect to generation | occurrence | production of a new driving | running state.

(B) In the gas engine 1 according to the present embodiment, the specific operation state is a load application, and the state detector is a load application detector (the rotation speed detector 4 and the controller 7) that detects the occurrence of the load application. is there.

  For this reason, the gas engine 1 according to the present embodiment can change the gas pressure applied to the sub chamber 2b without causing a delay with respect to the occurrence of a new load.

(C) In the gas engine 1 according to the present embodiment, the rotational speed of the gas engine 1 is controlled so as to coincide with the set target rotational speed RT, and the load application detector (the rotational speed detector 4 and the controller). 7) detects the occurrence of load application when the rotational speed is lower than the target rotational speed RT by a predetermined width WR or more.

  The engine that controls the rotational speed to the target rotational speed RT includes a rotational speed detector 4. For this reason, the gas engine 1 according to the present embodiment can easily detect the occurrence of the load without providing a new detection means for detecting the occurrence of the load.

(D) The gas engine 1 according to this embodiment includes an output detector (power detector 31) that detects the output of the gas engine 1, and the load input detector has an upper limit and a lower limit load factor LL. , LH is detected, and the occurrence of load application is detected when the rotational speed decreases.

  As the output increases, the fluctuation range of the rotational speed generated by applying a new load decreases. That is, as the output increases, the necessity of controlling the gas pressure in the sub chamber 2b to reduce fluctuations in the rotational speed decreases. Further, even when the load is extremely small, the necessity of controlling the gas pressure in the sub chamber 2b in order to suppress fluctuations in the rotational speed is reduced. For this reason, the gas engine 1 according to the present embodiment can prevent unnecessary control from being executed when it is less necessary to change the gas pressure in order to suppress fluctuations in the rotational speed.

(Configuration of Second Embodiment)
With reference to FIG. 5, the gas engine 1 which concerns on 2nd Embodiment is demonstrated. The configuration of the main supply mechanism 5 is changed between the first embodiment and the second embodiment. The main supply mechanism 5 according to the second embodiment employs a carburetor system, and the main supply mechanism 5 according to the first embodiment employs an injector system. Other points are the same between the first embodiment and the second embodiment.

  FIG. 5 is a diagram illustrating a configuration of the gas engine 1. The main supply mechanism 5 according to the second embodiment includes an intake passage 20, a gas passage 21, a throttle valve 22, a first original valve 24, a second original valve 24, and a pressure regulating valve 25. The throttle valve 22 is disposed on the intake path 20 downstream of the junction 20a. The throttle valve 22 determines the opening degree of the intake passage 20, thereby changing the flow rate of the air-fuel mixture. For this reason, the rotational speed increases and decreases as the opening degree of the throttle valve 20 increases and decreases.

(Modification)
The gas engine 1 according to the present embodiment can employ the following modified configuration.

  The specific operating state is not limited to load input. Any one of the start operation, the acceleration operation, and the steady operation may be set to a specific operation state. Further, the gas engine 1 may include a plurality of pressure adjusting units with different opening degrees of the orifices 19 so that the gas pressure applied to the sub chamber 2b can be changed according to three or more different operation states.

  The pressure regulation unit 13 may include a pressure regulation valve instead of the orifice 19. Unlike the orifice 19, the pressure regulating valve can change the opening degree. The user can set the opening degree of the pressure regulating valve so as to be suitable for a desired operation state.

  In the present embodiment, the occurrence of load application is specified based on a temporary decrease in the rotational speed. Instead of lowering the rotation speed, the occurrence of load application may be specified based on the state of the switch (connected or disconnected) or a control command for executing load application. In this case, the gas engine 1 has a detector for detecting the state of the switch or a detector for detecting a load application control command.

  In the present embodiment, the output of the gas engine 1 is specified based on the output power of the generator 30 driven by the gas engine 1. Instead of this, the output of the gas engine 1 may be directly specified. Since the output of the gas engine 1 is defined by the rotational speed and the torque, the output is specified based on the rotational speed, the intake air amount, and the air-fuel ratio. The intake air amount is specified by the throttle valve 22. In the first embodiment, the air-fuel ratio is specified mainly based on the opening degrees of the fuel injection device 26 and the pressure regulating valve 25. In the second embodiment, the air-fuel ratio is specified mainly based on the opening degree of the pressure regulating valve 25.

1 Gas engine 4 Rotation speed detector (part of status detector and load detector)
7 Controller (part of status detector and load detector, and control device)
8 path 12 pressure regulating valve 13 pressure regulating unit 16 OFF path 17 on-off valve 18 ON path 19 orifice 31 power detector (output detector, part of state detector and load input detector)

Claims (4)

In the sub-chamber type gas engine having a main pressure regulating valve for adjusting the gas pressure applied to the sub-chamber in the path for supplying the fuel gas to the sub-chamber,
An OFF path branched from the path and joined to the path, an on-off valve arranged on the OFF path, an ON path branched from the path and joined to the path, and arranged on the ON path A pressure regulating unit having an orifice or a pressure regulating valve and disposed in the path between the main pressure regulating valve and the sub chamber;
A state detector that detects the occurrence of a specific operating state;
A control device that temporarily closes the on-off valve when the occurrence of the specific operating state is detected, and
The opening / closing valve discretely changes the opening of the OFF path to open or closed, the opening of the path when the opening / closing valve is open is equal to the opening of the main pressure regulating valve, and the opening / closing valve is closed. In this case, the opening degree of the path is equal to the opening degree of the orifice or the pressure regulating valve . The specific operating state is a load input,
The sub-chamber gas engine according to claim 1, wherein the state detector is a load input detector that detects the occurrence of the load input. The rotational speed of the gas engine is controlled to match the set target rotational speed,
The sub-chamber gas engine according to claim 2, wherein the load application detector detects the occurrence of a decrease in the rotational speed when the rotational speed is decreased by a predetermined width or more than the target rotational speed.   An output detector for detecting the output of the gas engine, the load input detector detects the occurrence of load input when the load factor is within a range of an upper limit and a lower limit load factor and the rotational speed decreases; The sub-chamber type gas engine according to claim 2.

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