engine

Abstract

To provide an engine capable of further quickly reducing sub chamber gas pressure and ensuring good load responsivity.SOLUTION: A gas engine 1 is equipped with a sub chamber 21 that ignites fuel gas to generate flame, and a main chamber 20 that burns fuel gas / air mixture by using the flame generated in the sub chamber 21, as a combustion chamber of each cylinder 11. The engine is equipped with a sub chamber main pipe 39 that supplies the fuel gas into the sub chamber 21, an air supply passage 32 that circulates air to be supplied to the main chamber 20, and a communication pipe 41 that communicates from the sub chamber main pipe 39 to the air supply passage 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an engine having a main combustion chamber and an auxiliary combustion chamber. [Background technology]

[0002] Conventionally, engines include a pre-chamber gas engine that has, as combustion chambers, a pre-chamber in which fuel gas is ignited to generate a flame, and a main chamber in which a mixture of fuel gas and air is burned using the flame generated in the pre-chamber.

[0003] Also, as disclosed in Patent Document 1, for example, some gas engines mix fuel gas introduced through a fuel flow control valve with air flowing through an intake pipe, and supply this mixture to the combustion chamber with its flow rate adjusted by a throttle valve. This integrated control method for gas engines includes a process of setting the fuel gas flow rate of the fuel flow control valve based on the deviation between the detected engine state and the target engine state, and a process of performing feedback control to set the target opening of the throttle valve. This improves load responsiveness while maintaining highly accurate air-fuel ratio control. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-57870 A Summary of the Invention [Problem to be solved by the invention]

[0005] The air-fuel ratio control as disclosed in Patent Document 1 may be applied to a pre-chamber gas engine to control the air-fuel ratio in the pre-chamber. For example, in a configuration in which a check valve is provided to supply fuel gas to the pre-chamber, the gas pressure in the pre-chamber main pipe upstream of the check valve is controlled to be higher than the pressure in the intake manifold (i.e., the pressure in the combustion chamber), thereby controlling the amount of fuel gas flowing into the pre-chamber from the check valve to be in a stoichiometric state. The target gas pressure in the pre-chamber main pipe is an adapted value determined depending on the load rate, and PID control is performed using a proportional valve upstream of the pre-chamber main pipe so that the gas pressure in the pre-chamber main pipe follows the target gas pressure.

[0006] When the engine is loaded, the fuel gas supply to the main chamber increases rapidly, so that the air-fuel ratio in the pre-chamber also becomes rich. In order to prevent the air-fuel ratio in the pre-chamber from deviating from the flammable range, the gas pressure in the pre-chamber (pre-chamber gas pressure) is controlled to be rapidly lowered when the load is applied, so that the target gas pressure is lowered and the proportional valve is displaced to the closed state. In this case, in the conventional technology, in order to lower the gas pressure in the pre-chamber main pipe with the proportional valve displaced to the closed state, the gas in the pre-chamber main pipe needs to flow into the pre-chamber through the check valve, so the pre-chamber gas pressure cannot be lowered rapidly. In addition, if the pre-chamber gas pressure is limited by the gas flow rate of the check valve and it takes time to sufficiently lower, and the proportional valve opening reaches the fully closed state, there is a response delay until the proportional valve opens when it is desired to increase the pre-chamber gas pressure. As a result of the response delay, the air-fuel ratio in the pre-chamber cannot be appropriately controlled, causing a misfire, which may result in failure to apply the load.

[0007] An object of the present invention is to provide an engine that can reduce the pre-chamber gas pressure more quickly and ensure good load responsiveness. [Means for solving the problem]

[0008] In order to solve the above problems, the engine of the present invention is an engine having as combustion chambers an auxiliary chamber in which fuel gas is ignited to generate a flame, and a main chamber in which a mixture of fuel gas and air is burned using the flame generated in the auxiliary chamber, and is characterized in having an auxiliary chamber main pipe which supplies fuel gas to the auxiliary chamber, an intake passage through which air is supplied to the main chamber, and a connecting pipe which connects the auxiliary chamber main pipe to the intake passage. Effect of the Invention

[0009] According to the present invention, an engine is provided that can reduce the pre-chamber gas pressure more quickly and ensure good load responsiveness. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a gas engine according to an embodiment of the present invention. FIG. [Diagram 2] 1 is a schematic diagram showing each cylinder of a gas engine according to an embodiment of the present invention. FIG. [Diagram 3] 5 is a graph showing an example of operation of the gas engine according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A gas engine 1 according to an embodiment of the engine of the present invention will be described with reference to the drawings. As shown in Fig. 1, the gas engine 1 includes an engine body 2, an intake mechanism 3, an exhaust mechanism 4, and a control device 5.

[0012] First, the engine body 2 will be described. The engine body 2 is configured with a cylinder block 10 and a plurality of cylinders 11. As shown in Fig. 2, each cylinder 11 is configured with a cylinder 13, a piston 14, a cylinder head 15, and an ignition device 16. Note that in this specification, the supply of the mixture to each cylinder 11 is referred to as "intake air," and the supply of air that is the source of the mixture is referred to as "supply air."

[0013] The cylinder 13 is formed, for example, in a cylindrical shape within the cylinder block 10, and the piston 14 is slidably housed within the cylinder 13. The cylinder head 15 is attached to the upper side of the cylinder 13, and the cylinder 13 and the cylinder head 15 form a combustion chamber therein.

[0014] In particular, a main chamber 20, which is a main combustion chamber, is formed between the piston 14 and the cylinder head 15 inside the cylinder 13, and an auxiliary chamber 21, which is an auxiliary combustion chamber communicating with the main chamber 20 of the cylinder 13, is formed inside the lower part of the cylinder head 15. A check valve 22 is provided above the auxiliary chamber 21 inside the cylinder head 15, and the check valve 22 is connected to an auxiliary chamber main pipe 39 (see FIG. 1) of the intake mechanism 3, and fuel gas is introduced into the auxiliary chamber 21 through the auxiliary chamber main pipe 39 and the check valve 22. The check valve 22 is configured to open and close according to the differential pressure between the gas pressure in the auxiliary chamber 21 (i.e., the mixture pressure in the main chamber 20) and the gas pressure in the auxiliary chamber main pipe 39.

[0015] For example, when the gas pressure in the auxiliary chamber 21 (air-fuel mixture pressure in the main chamber 20) is high and the differential pressure between the gas pressure in the auxiliary chamber main pipe 39 is less than a predetermined check threshold, the check valve 22 is shifted to a closed state to cut off the supply of fuel gas to the auxiliary chamber 21. On the other hand, when the gas pressure in the auxiliary chamber 21 (air-fuel mixture pressure in the main chamber 20) is low and the differential pressure between the gas pressure in the auxiliary chamber main pipe 39 is equal to or greater than a predetermined check threshold, the check valve 22 is shifted to an open state to supply fuel gas to the auxiliary chamber 21. The differential pressure between the auxiliary chamber 21 and the auxiliary chamber main pipe 39 can be adjusted by adjusting the gas pressure in the auxiliary chamber main pipe 39 to a target gas pressure using the auxiliary chamber proportional valve 40 (see FIG. 1), and the amount of fuel gas supplied to the auxiliary chamber 21 can be adjusted by adjusting the opening of the check valve 22. Specifically, the air-fuel ratio of the mixture generated in the auxiliary chamber 21 by the fuel gas flowing from the check valve 22 into the auxiliary chamber 21 is controlled to be stoichiometric.

[0016] The cylinder head 15 also has an intake port 23 and an exhaust port 24 that communicate with the main chamber 20 of the cylinder 13, and is equipped with an intake valve 25 and an exhaust valve 26 that open and close the intake port 23 and the exhaust port 24, respectively, to the main chamber 20. The intake port 23 is connected to the intake mechanism 3 and introduces a mixture of fuel gas and air from the intake mechanism 3 into the main chamber 20, and the exhaust port 24 is connected to the exhaust mechanism 4 and discharges exhaust gas generated in the main chamber 20 to the exhaust mechanism 4. By opening the intake valve 25, the mixture of fuel gas and air can be taken into the main chamber 20 via the intake port 23, while by opening the exhaust valve 26, the exhaust gas generated in the main chamber 20 can be exhausted via the exhaust port 24.

[0017] The ignition device 16 is provided above the auxiliary chamber 21 in the cylinder head 15, and includes an ignition plug 27 exposed to the auxiliary chamber 21. The ignition device 16 is controlled by the control device 5, and ignites the fuel gas introduced into the auxiliary chamber 21 via the auxiliary chamber main pipe 39 and the check valve 22 with the ignition plug 27, thereby generating a flame in the auxiliary chamber 21, and ejects the flame generated in the auxiliary chamber 21 into the main chamber 20. In the main chamber 20, the mixture of fuel gas and air taken in via the intake port 23 is combusted using the flame generated in the auxiliary chamber 21.

[0018] Next, the intake mechanism 3 will be described. As shown in Fig. 1, the intake mechanism 3 includes an intake manifold 30, a fuel gas passage 31, and an intake passage 32. The intake manifold 30 supplies a mixture of fuel gas and air to the multiple cylinders 11. The intake manifold 30 branches out so as to correspond to each of the multiple cylinders 11, and is connected to each intake port 23 of the multiple cylinders 11. In other words, each branch flow path (not shown) of the intake manifold 30 is connected to each intake port 23.

[0019] The intake passage 32 passes air, which is the source of the air-fuel mixture to be supplied to the cylinders 11, to the intake manifold 30. The intake passage 32 is connected to the intake manifold 30 at a downstream end in the intake direction, and supplies air to each branch flow path (not shown) branched from the intake manifold 30 corresponding to each intake port 23. The intake passage 32 is provided with an air filter 33 that purifies fresh air and introduces it, a supercharger 34 that compresses the air introduced from the air filter 33 and sends it downstream, and an intercooler 35 that cools the air compressed by the supercharger 34, in this order from the upstream side in the intake direction. The intake passage 32 is also provided with a throttle valve (not shown) that can adjust the amount of air supplied, and the throttle valve is controlled by the control device 5 to open and close and to open and close to supply air to each intake port 23.

[0020] The fuel gas passage 31 passes fuel gas, which is the source of the air-fuel mixture supplied to the multiple cylinders 11, to the intake manifold 30. In Fig. 1, the fuel gas passage 31 is illustrated as being connected to the intake manifold 30, but the fuel gas passage 31 is connected to each gas injector (not shown) provided in each branch flow path branched from the intake manifold 30 to each intake port 23, and the fuel gas passing through the fuel gas passage 31 is supplied to each intake port 23 by each gas injector. Each gas injector is controlled by the control device 5 to inject fuel gas into each intake port 23.

[0021] A gas compressor 36 is provided upstream of the fuel gas passage 31 in the fuel gas supply direction, and the fuel gas passage 31 is further branched into a main chamber passage 37 and a sub-chamber passage 38 downstream of the gas compressor 36 in the fuel gas supply direction. The main chamber passage 37 branches to correspond to each of the multiple cylinders 11, and is connected to each gas injector of each intake port 23 downstream in the fuel gas supply direction to supply fuel gas to each gas injector.

[0022] The auxiliary chamber passage 38 is connected to an auxiliary chamber main pipe 39 on the downstream side in the fuel gas supply direction, and the auxiliary chamber main pipe 39 is further connected to a check valve 22 provided in each cylinder head 15 of the multiple cylinders 11. An auxiliary chamber proportional valve 40 is provided in the auxiliary chamber passage 38 on the upstream side in the fuel gas supply direction.

[0023] The pre-chamber proportional valve 40 is composed of an electromagnetic valve or the like, and is controlled by the control device 5 to be opened or closed. The pre-chamber passage 38 supplies fuel gas to the pre-chamber main pipe 39 by opening the pre-chamber proportional valve 40, while the pre-chamber passage 38 cuts off the supply of fuel gas to the pre-chamber main pipe 39 by closing the pre-chamber proportional valve 40. By adjusting the opening of the pre-chamber proportional valve 40, the amount of fuel gas supplied to the pre-chamber main pipe 39 can be adjusted, and the gas pressure in the pre-chamber main pipe 39 can be adjusted to a target gas pressure by the pre-chamber proportional valve 40.

[0024] Particularly in this embodiment, a communication pipe 41 communicating with the intake passage 32 is connected to the pre-chamber main pipe 39 of the pre-chamber passage 38. The communication pipe 41 is configured to reduce the gas pressure in the pre-chamber main pipe 39 by releasing the fuel gas in the pre-chamber main pipe 39 into the intake passage 32. The communication pipe 41 is preferably connected to the intake passage 32 upstream of the turbocharger 34 in the intake direction of the intake passage 32. The communication pipe 41 is provided with a relief valve 42 capable of adjusting the flow rate of fuel gas from the pre-chamber main pipe 39 to the intake passage 32, and an orifice 43 that restricts the flow rate of fuel gas to the intake passage 32 to a predetermined amount.

[0025] The relief valve 42 is constituted by an electromagnetic proportional valve or the like, and is controlled by the control device 5 to be displaced to an open state or a closed state. When the relief valve 42 is in an open state, the connecting pipe 41 releases the fuel gas in the auxiliary chamber main pipe 39 to the intake passage 32, while when the relief valve 42 is in a closed state, the connecting pipe 41 blocks the escape of the fuel gas from the auxiliary chamber main pipe 39 via the connecting pipe 41. By adjusting the opening degree of the relief valve 42, the flow rate of the fuel gas escaping from the auxiliary chamber main pipe 39 via the connecting pipe 41 can be adjusted.

[0026] Next, the exhaust mechanism 4 will be described. The exhaust mechanism 4 includes an exhaust manifold 45 and an exhaust passage 46. The exhaust manifold 45 discharges exhaust gas generated in the multiple cylinders 11. The exhaust manifold 45 branches out so as to correspond to each of the multiple cylinders 11 and is connected to each exhaust port 24 of the multiple cylinders 11; in other words, each branch flow path (not shown) of the exhaust manifold 45 is connected to each exhaust port 24. The exhaust passage 46 flows to exhaust the exhaust gas generated in the multiple cylinders 11 and discharged from the exhaust manifold 45.

[0027] Next, we will explain the control device 5. The control device 5 is a computer such as an ECU (Engine Control Unit) that controls the operation of the gas engine 1, and is equipped with a CPU, ROM, RAM, etc., and is configured to control each part of the gas engine 1. The control device 5 may store various programs for controlling the gas engine 1, and control the gas engine 1 by reading and executing the programs.

[0028] The gas engine 1 is also provided with various sensors, such as a rotation speed sensor that detects the rotation speed (rotational speed) of the gas engine 1, a main chamber gas pressure sensor that detects the gas pressure in the main chamber passage 37, and an auxiliary chamber gas pressure sensor that detects the gas pressure in the auxiliary chamber main pipe 39. The control device 5 is connected to the various sensors, and monitors each part of the gas engine 1 by acquiring the rotation speed of the gas engine 1 detected by the rotation speed sensor, the gas pressure in the main chamber passage 37 detected by the main chamber gas pressure sensor, and the gas pressure in the auxiliary chamber main pipe 39 detected by the auxiliary chamber gas pressure sensor.

[0029] The control device 5 has a function of controlling the number of revolutions (rotation speed) of the gas engine 1 and the air-fuel ratio in each main chamber 20 of the multiple cylinders 11, and for example, controls the air-fuel ratio of each main chamber 20 so that the number of revolutions of the gas engine 1 becomes a target number of revolutions. For example, the control device 5 controls the amount of fuel gas supplied from each gas injector corresponding to each intake port 23 of the multiple cylinders 11 based on the number of revolutions and the load factor of the gas engine 1, and controls the number of revolutions of the gas engine 1 to become a target number of revolutions. The control device 5 controls the throttle valve of the intake passage 32 and each gas injector corresponding to each intake port 23, etc., to control the air-fuel ratio of each main chamber 20 to be in a lean state, and controls the ignition timing of the mixture in each main chamber 20 by controlling the spark plug 27 of each ignition device 16 of the multiple cylinders 11.

[0030] Furthermore, the control device 5 sets the target gas pressure of the pre-chamber main pipe 39 for the intake mechanism 3 based on the gas pressure of each intake port 23 of the intake manifold 30 and the load factor of the gas engine 1, and PID controls the opening and closing of the pre-chamber proportional valve 40 so that the pressure of the fuel gas in the pre-chamber main pipe 39 becomes the target gas pressure. The control device 5 controls the air-fuel ratio of the mixture generated by the fuel gas flowing into the pre-chamber 21 from the check valve 22 to be stoichiometric by setting the target gas pressure of the pre-chamber main pipe 39 higher than the gas pressure in the pre-chamber 21 (i.e., the mixture pressure in the main chamber 20).

[0031] Particularly in this embodiment, the control device 5 operates as a relief valve control unit 50 that controls the relief valve 42, and the relief valve control unit 50 may be configured by a program executed by the control device 5, etc.

[0032] The relief valve control unit 50 of the control device 5 switches the relief valve 42 to an open state when a predetermined condition (for example, a condition based on the operating state of the gas engine 1 and a predetermined elapsed time) is satisfied, thereby making the auxiliary chamber main pipe 39 and the supply passage 32 communicate with each other through the connecting pipe 41. The relief valve control unit 50 normally maintains the relief valve 42 in a closed state, switches the relief valve 42 to an open state when a condition based on the operating state of the gas engine 1 and a predetermined elapsed time is satisfied, and switches the relief valve 42 to a closed state again when a condition based on the operating state of the gas engine 1 and a predetermined blocking time is satisfied. In addition, the relief valve control unit 50 may have a primary filter that gradually changes the relief valve 42 from a closed state to an open state and gradually changes the relief valve 42 from an open state to a closed state.

[0033] Specifically, the relief valve control unit 50 starts changing the relief valve 42 to the open state after a predetermined elapsed time (e.g., 5 seconds) from when the gas engine 1 is started and the rotation speed of the gas engine 1 reaches a predetermined rated rotation speed. That is, the predetermined condition for switching the relief valve 42 to the open state is set based on the operating state of the gas engine 1 and the predetermined elapsed time.

[0034] In addition, the relief valve control unit 50 controls the gas engine 1 to start and open the relief valve 42, and then when a load is applied to the gas engine 1, the relief valve control unit 50 controls the gas engine 1 to start and close the relief valve 42 when a predetermined first closing time (e.g., 5 seconds) has elapsed since the load factor of the gas engine 1 reached a predetermined load threshold value (e.g., 30%) or more, and the rotation speed of the gas engine 1 reaches a predetermined rotation speed threshold value (e.g., 1480 min -1 ) or more, and then after a predetermined second blocking time (for example, 5 seconds) has elapsed, the relief valve 42 starts to shift to the closed state.

[0035] In addition, the specified elapsed time and the specified blocking times such as the first blocking time and the second blocking time may be preset values, or may be arbitrarily set by the user, or may be changed depending on the operating state of the gas engine 1.

[0036] Next, an example of the operation of the gas engine 1 will be described with reference to FIG. 3. In FIG. 3, the rotation speed of the gas engine 1 is indicated by a thin dashed line, and the load factor of the gas engine 1 is indicated by a thin dashed double-dot line. In FIG. 3, the target mixed gas pressure in the main chamber 20 is indicated by a thick dashed line, and the mixed gas pressure in the main chamber 20 is indicated by a thin dashed line. In FIG. 3, the target gas pressure in the auxiliary chamber main pipe 39 is indicated by a thick solid line, and the gas pressure in the auxiliary chamber main pipe 39 is indicated by a thin solid line. In FIG. 3, the opening of the auxiliary chamber proportional valve 40 is indicated by a thick dashed double-dot line, and the opening of the relief valve 42 is indicated by a thick dashed double-dot line.

[0037] First, when the gas engine 1 is started at time t1, the control device 5 controls each part to increase the rotation speed of the gas engine 1. After the rotation speed of the gas engine 1 reaches a predetermined rated rotation speed at time t2, the relief valve control part 50 starts to shift the relief valve 42 to the open state at time t3, which is a predetermined time (e.g., 5 seconds) after the rotation speed of the gas engine 1 reaches a predetermined rated rotation speed at time t2.

[0038] After that, when a load is applied to the gas engine 1 at time t4, the control device 5 lengthens the injection time of the main chamber 20 to increase the fuel gas supplied to the main chamber 20. At this time, in order to prevent the fuel gas in the auxiliary chamber 21 from becoming rich, the control device 5 sets the target gas pressure of the auxiliary chamber main pipe 39 low and displaces the auxiliary chamber proportional valve 40 to a closed state in order to lower the gas pressure in the auxiliary chamber 21. Incidentally, in order to lower the gas pressure in the auxiliary chamber main pipe 39, a means for allowing the fuel gas in the auxiliary chamber main pipe 39 to flow into the auxiliary chamber 21 via the check valve 22 is considered. In that case, during the period until the gas pressure in the auxiliary chamber main pipe 39 drops to the target gas pressure, more fuel gas than necessary flows into the auxiliary chamber 21, so that the excessively rich state of the fuel gas in the auxiliary chamber 21 continues. Furthermore, since the rate at which the gas pressure in the adjoining main pipe 39 drops is determined by the flow rate (gas flow rate) of the check valve 22, there is a risk that the opening of the adjoining proportional valve 40 will be stuck at its lower limit and will be in a fully closed state before the gas pressure in the adjoining main pipe 39 drops sufficiently. Once the adjoining proportional valve 40 is in a fully closed state, even if it is subsequently desired to increase the gas pressure in the adjoining main pipe 39, a response delay occurs between the time the adjoining proportional valve 40 goes from the fully closed state to the time it opens, making it difficult to quickly make the gas pressure in the adjoining main pipe 39 follow the target gas pressure. In contrast, in this embodiment, the relief valve 42 is open and the connecting pipe 41 connects the auxiliary chamber main pipe 39 and the supply passage 32, so that the gas in the auxiliary chamber main pipe 39 can be released to the supply passage 32 via the connecting pipe 41 and the gas pressure in the auxiliary chamber main pipe 39 can be quickly lowered, so that there is no period during which the fuel gas in the auxiliary chamber 21 becomes excessively rich and the opening of the auxiliary chamber proportional valve 40 does not stick to the lower limit. This allows the gas pressure in the auxiliary chamber main pipe 39 to quickly follow the target gas pressure.

[0039] In addition, the relief valve control unit 50 begins to change the relief valve 42 to a closed state at time t5, which is a predetermined first blocking time after the load factor of the gas engine 1 reaches a predetermined load threshold or higher, and a predetermined second blocking time after the rotational speed of the gas engine 1 reaches a predetermined rotational speed threshold or higher.

[0040] In the above embodiment, the operating state of the gas engine 1 when the relief valve control unit 50 opens the relief valve 42 is described as a predetermined time after the gas engine 1 is started and the rotation speed of the gas engine 1 reaches a predetermined rated rotation speed, but the present invention is not limited to this example. For example, the relief valve control unit 50 may control the relief valve 42 to open when the gas pressure in the auxiliary main pipe 39 is high and the check valve 22 and the auxiliary proportional valve 40 cannot be quickly shifted from the closed state to the open state.

[0041] In the above embodiment, the example in which the communication pipe 41 is connected to the air supply passage 32 upstream of the turbocharger 34 in the air supply direction has been described, but the present invention is not limited to this example. For example, the communication pipe 41 may be connected to the air supply passage 32 at a position other than the upstream side of the turbocharger 34, or may be connected to another position (for example, the exhaust passage 46, etc.).

[0042] In addition, the relief valve control unit 50 may control the relief valve 42 to open only when the first load is applied after the gas engine 1 is started, or may control the relief valve 42 to open each time a load is applied depending on the operating state of the gas engine 1.

[0043] As described above, according to the present invention, the gas engine 1 is an engine having, as combustion chambers for each cylinder 11, an auxiliary chamber 21 in which fuel gas is ignited to generate a flame, and a main chamber 20 in which a mixture of fuel gas and air is burned using the flame generated in the auxiliary chamber 21, and is also provided with an auxiliary chamber main pipe 39 which supplies fuel gas to the auxiliary chamber 21, an intake passage 32 which circulates air supplied to the main chamber 20, and a connecting pipe 41 which connects the auxiliary chamber main pipe 39 to the intake passage 32.

[0044] As a result, according to the gas engine 1 of the present invention, the gas in the auxiliary chamber main pipe 39 can be released through the connecting pipe 41, so that the gas pressure in the auxiliary chamber main pipe 39 can be reduced. Therefore, in a configuration in which the auxiliary chamber 21 is connected to the auxiliary chamber main pipe 39 through the check valve 22, the gas pressure in the auxiliary chamber 21 can be quickly reduced by reducing the gas pressure in the auxiliary chamber main pipe 39 through the connecting pipe 41. For example, when the load of the gas engine 1 is applied, the amount of fuel gas supplied to the main chamber 20 is increased, so that the fuel gas in the auxiliary chamber 21 does not become excessively rich. Here, if a means for flowing the fuel gas in the auxiliary chamber main pipe 39 into the auxiliary chamber 21 through the check valve 22 is applied as a means for reducing the gas pressure in the auxiliary chamber main pipe 39, the gas pressure in the auxiliary chamber main pipe 39 will not track the target gas pressure as described above. In contrast, in the gas engine 1 of the present invention, as described above, the gas pressure in the pre-chamber main pipe 39 is reduced by the connecting pipe 41, so that the gas pressure in the pre-chamber 21 can be reduced more quickly, ensuring good load responsiveness.

[0045] The gas engine 1 of the present invention also includes a turbocharger 34 that compresses the air supplied to the main chamber 20, and the connecting pipe 41 is connected to the intake passage 32 upstream of the turbocharger 34 in the air supply direction to the main chamber 20. As a result, in the gas engine 1 equipped with the turbocharger 34, the connecting pipe 41 connected to the intake upstream side of the turbocharger 34 can promote flow from the pre-chamber main pipe 39 to the intake passage 32 by utilizing the intake negative pressure generated by the turbocharger 34, and can more effectively release the gas pressure in the pre-chamber main pipe 39.

[0046] In the gas engine 1 of the present invention, the connecting pipe 41 is provided with a relief valve 42 capable of adjusting the flow rate of fuel gas from the auxiliary main pipe 39 to the intake passage 32. As a result, when the gas engine 1 is started, the connecting pipe 41 is closed by the relief valve 42 to quickly increase the gas pressure in the auxiliary main pipe 39 and ensure responsiveness to load application, while the connecting pipe 41 is opened by the relief valve 42 until the load application of the gas engine 1, ensuring the ability of the auxiliary main pipe 39 to follow the target gas pressure when the load is applied.

[0047] Furthermore, when a predetermined condition (a condition based on the engine operating state and a predetermined elapsed time) is satisfied, the gas engine 1 of the present invention switches the relief valve 42 to an open state, and brings the auxiliary main pipe 39 and the intake passage 32 into communication with each other through the connecting pipe 41. This allows the gas engine 1 to suppress fluctuations in gas pressure in the auxiliary main pipe 39 caused by opening and closing of the relief valve 42.

[0048] In the above embodiment, the predetermined condition for switching the relief valve 42 to the open state is based on the engine operating state and a predetermined elapsed time. Specifically, the case where a predetermined elapsed time has elapsed since the gas engine 1 was started and the rotation speed of the gas engine 1 reached a predetermined rated rotation speed was described as an example, but the present invention is not limited to this example. For example, the engine operating state is not limited to when the gas engine 1 was started and the rotation speed of the gas engine 1 reached a predetermined rated rotation speed, and may be other timing. In another embodiment, the predetermined condition for switching the relief valve 42 to the open state is set based on the differential pressure between the gas pressure in the auxiliary chamber main pipe 39 and the gas pressure in the auxiliary chamber 21. For example, the gas pressure in the auxiliary chamber main pipe 39 may be higher than the gas pressure in the auxiliary chamber 21 by a predetermined threshold value or more.

[0049] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or concept of the invention that can be read from the claims and the entire specification, and gas engines with such modifications are also included in the technical concept of the present invention. [Explanation of symbols]

[0050] 1 Gas engine (engine) 5. Control device 11 cylinders 16 Ignition system 20 Main room 21 Antechamber 22 Check valve 27 Spark plug 30 Intake manifold 31 Fuel gas passage 32 Air supply passage 34 Turbocharger 39 Sub-room supervisor 40 Subchamber proportional valve 41 Connecting Pipe 42 Relief valve 50 Relief valve control section

Claims

1. An engine having a sub-chamber for igniting a fuel gas to generate a flame as a combustion chamber, and a main chamber for burning a mixture of the fuel gas and air using the flame generated in the sub-chamber, a sub-chamber main pipe for supplying fuel gas to the sub-chamber; an air supply passage through which air is supplied to the main chamber; a connecting pipe that is in communication with the air supply passage from a downstream side of an inlet portion of the auxiliary chamber in the auxiliary chamber main pipe for introducing fuel gas into the auxiliary chamber; An engine comprising:

2. A supercharger is provided to compress air supplied to the main chamber, 2. The engine according to claim 1, wherein the communication pipe is connected to the intake passage upstream of the turbocharger in a direction in which air is supplied to the main chamber.

3. 3. The engine according to claim 1, wherein the communication pipe is provided with a relief valve capable of adjusting a flow rate of fuel gas from the sub-chamber main pipe to the intake passage.

4. 4. The engine according to claim 3, wherein the relief valve is switched to an open state when a predetermined condition is satisfied, so that the auxiliary main pipe and the intake passage are in a communication state through the connecting pipe.

5. 5. The engine according to claim 4, wherein the predetermined condition is that a predetermined time has elapsed since the engine speed reached a predetermined rated speed, or that the gas pressure in the auxiliary chamber main pipe is higher than the gas pressure in the auxiliary chamber by a predetermined threshold value or more.

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