Engine device and control method for engine device

Abstract

To provide an engine device that can be operated by suppressing abnormal combustion by more appropriately determining an abnormal combustion suppression method, and a control method for the engine device.SOLUTION: An engine device 1 driven by gas fuel detects abnormal combustion that has occurred in a combustion chamber 12a of an engine 2, monitors occurrence frequency and occurrence intensity of the abnormal combustion, and determines a suppression method for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity. As the suppression method, the engine device 1 controls at least one of ignition timing of the gas fuel, an excess air ratio of suction air in an air-fuel mixture comprising the gas fuel and the suction air, and shut-off of the gas fuel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an engine device that is driven by injecting gaseous fuel into a combustion chamber, and a control method thereof. [Background technology]

[0002] Conventionally, engine devices include gas engines that are driven by feeding gaseous fuel such as hydrogen into a combustion chamber in a cylinder, and dual-fuel engines that are driven by feeding at least one of gaseous fuel such as hydrogen and liquid fuel such as light oil or heavy oil into a combustion chamber in a cylinder. For example, a dual-fuel engine operates in one of two operating modes: a gas mode in which gaseous fuel is fed into the combustion chamber and driven by feeding liquid fuel into the combustion chamber, and a mixed-fuel mode in which both gaseous fuel and liquid fuel are fed into the combustion chamber as another operating mode. In such engine devices, abnormal combustion such as pre-ignition (premature ignition) in which gaseous fuel self-ignites in the combustion chamber before ignition by a micro-pilot system that injects a small amount of liquid fuel or ignition by a spark ignition system ignition device using a spark plug may occur, so it is necessary to suppress abnormal combustion.

[0003] For example, according to Patent Document 1, a control device for an internal combustion engine includes an occurrence frequency detection means for detecting the frequency of occurrence of pre-ignition per unit time, and a temperature range varying means for changing the range of the pre-ignition suppression temperature range when the occurrence frequency of pre-ignition exceeds an allowable limit in at least a portion of the pre-ignition suppression temperature range so that the occurrence frequency of pre-ignition is equal to or lower than the allowable limit in the portion of the range. Then, a cylinder wall temperature control means of this control device controls the wall temperature parameter to fall within the pre-ignition suppression temperature range changed by the temperature range varying means.

[0004] According to Patent Document 2, a method for controlling combustion in a supercharged internal combustion engine with controlled ignition comprises the steps of: (a) selecting a physical model representing the progression of pressure in a cylinder within a range of a combustion without pre-ignition as a function of the angle of rotation of the crankshaft; (b) predicting the cylinder pressure from the physical model and a measured value of the intake pressure; (c) detecting the onset of abnormal combustion by comparing at least one first value of a variable calculated using the measured value of the cylinder pressure with at least one second value of a variable calculated using the predicted value of the cylinder pressure; characterizing the magnitude of the pre-ignition by repeating steps (b) and (c) at several determined crankshaft angles; and controlling the progression of the abnormal combustion detected in the combustion chamber depending on the magnitude of the pre-ignition phenomenon.

[0005] According to Patent Document 3, a combustion device for an internal combustion engine includes a fuel injection valve that injects gaseous fuel into a combustion chamber and an ignition plug that ignites the gaseous fuel injected by the fuel injection valve, the fuel injection valve is provided at a position where the injected gaseous fuel gathers around the spark plug, the internal combustion engine is driven by liquid fuel in addition to the gaseous fuel, and further includes a fuel switching means that switches the fuel for the internal combustion engine depending on the engine operating state, and when pre-ignition occurs in the internal combustion engine, the fuel switching means switches the fuel to drive the internal combustion engine only with liquid fuel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5939263 [Patent Document 2] Patent No. 5405950 [Patent Document 3] Patent No. 4075165 Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional technology such as that described in Patent Document 1 mentioned above, pre-ignition suppression control is determined by evaluating only the frequency of pre-ignition occurrence. Therefore, when the frequency of occurrence is low, even if abnormal combustion occurs in which the internal pressure (in-cylinder pressure) of the combustion chamber increases significantly, suppression control of abnormal combustion cannot be executed, and there is a risk of damage to the engine (internal combustion engine) due to the allowable in-cylinder pressure being exceeded.

[0008] On the other hand, in the conventional technology described in the above-mentioned Patent Document 2, the abnormal combustion suppression control is determined by evaluating only the increase in the internal pressure (cylinder pressure) of the combustion chamber. Therefore, when the increase in the cylinder pressure is small, even if abnormal combustion occurs that causes pre-ignition with a high frequency, the abnormal combustion suppression control cannot be executed.

[0009] As such, conventional technology only provides limited suppression methods for abnormal combustion such as pre-ignition that occurs due to various causes, so if the cause of abnormal combustion and the suppression method are not appropriately combined, abnormal combustion cannot be suppressed.

[0010] Furthermore, in the conventional technology described in the above-mentioned Patent Document 3, the operating time with gaseous fuels (hydrogen, ammonia, etc.), which are expected to reduce CO2 (carbon dioxide), is limited, so the effect of reducing greenhouse gases is limited, and the marketability of the engine device is reduced.

[0011] An object of the present invention is to provide an engine system and a control method thereof that can more appropriately determine a method for suppressing abnormal combustion and operate the engine while suppressing abnormal combustion. [Means for solving the problem]

[0012] In order to solve the above problems, the engine device of the present invention is an engine device powered by gaseous fuel, which detects abnormal combustion occurring in a combustion chamber, monitors the frequency and intensity of occurrence of the abnormal combustion, and determines a suppression method for suppressing the abnormal combustion in accordance with the frequency and intensity of occurrence.

[0013] Alternatively, the engine device of the present invention is an engine device that is powered by at least one of gaseous fuel and liquid fuel, and when powered by the gaseous fuel, detects abnormal combustion occurring in a combustion chamber, monitors the frequency and intensity of the abnormal combustion, and determines a suppression method for suppressing the abnormal combustion in accordance with the frequency and intensity of the abnormal combustion, and controls at least one of the suppression methods including the ignition timing of the gaseous fuel, the excess air ratio of the intake air in a mixture consisting of the gaseous fuel and the intake air, blocking of the gaseous fuel, and switching to drive by both the gaseous fuel and the liquid fuel or drive by only the liquid fuel.

[0014] In addition, in order to solve the above-mentioned problems, the control method for an engine device of the present invention is a control method for an engine device driven by gaseous fuel, which is characterized by detecting abnormal combustion occurring in a combustion chamber, monitoring the frequency and intensity of occurrence of the abnormal combustion, and determining a suppression method for suppressing the abnormal combustion in accordance with the frequency and intensity of occurrence. Effect of the Invention

[0015] According to the present invention, an engine system and a control method thereof are provided that can more appropriately determine a method for suppressing abnormal combustion and operate the engine while suppressing abnormal combustion. [Brief description of the drawings]

[0016] [Figure 1] 1 is a left side view showing an engine device according to an embodiment of the present invention. FIG. [Diagram 2] 2 is a graph showing an example of an operable region in the relationship between ignition timing and an excess air ratio in an engine device. [Diagram 3] 4 is a graph showing an example of a distribution of the occurrence frequency of abnormal combustion with respect to an operable region in the relationship between ignition timing and excess air ratio in an engine device according to an embodiment of the present invention. [Figure 4]4 is a graph showing an example of a distribution of the occurrence intensity of abnormal combustion with respect to an operable region in the relationship between the ignition timing and the excess air ratio in the engine device according to the embodiment of the present invention. [Diagram 5] FIG. 2 is a matrix diagram showing an example of a method for suppressing abnormal combustion according to the frequency and intensity of occurrence of abnormal combustion in an engine device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An engine device 1 according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG.

[0018] Particularly in this embodiment, the engine device 1 is a gas engine configured to be capable of being driven by injecting gaseous fuel such as hydrogen into the combustion chamber 12a of the engine 2, and is equipped with a gaseous fuel injection unit 6 for injecting the gaseous fuel, a throttle valve 7 for adjusting the amount of intake air, and an ignition device 8 for igniting the gaseous fuel in the combustion chamber 12a.

[0019] The engine 2 is configured with a cylinder block 11 and multiple cylinders 12, but Fig. 1 shows only one cylinder 12. As shown in Fig. 1, each cylinder 12 is configured with a cylinder 13, a piston 14, and a cylinder head 15. A gaseous fuel injection unit 6 and an ignition device 8 are provided for each cylinder 12.

[0020] The cylinder 13 is formed, for example, in a cylindrical shape within the cylinder block 11, 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 12a therein.

[0021] Below the cylinder 13 , a crankshaft 17 is connected to the piston 14 via a connecting rod 16 , and the reciprocating motion of the piston 14 is converted into the rotational motion of the crankshaft 17 via the connecting rod 16 .

[0022] An angle sensor 18 is provided in the cylinder 13 to detect the rotation angle of the crankshaft 17, i.e., the rotation speed of the engine 2, and the angle sensor 18 transmits the detection result to the control unit 5. A pressure sensor 19 is provided in the cylinder 13 to detect the internal pressure of the combustion chamber 12a, i.e., the in-cylinder pressure of the cylinder 13, and the pressure sensor 19 transmits the detection result to the control unit 5.

[0023] The cylinder head 15 also has an intake port 22 and an exhaust port 23 that communicate with the combustion chamber 12a of the cylinder 13, and is equipped with an intake valve 24 and an exhaust valve 25 that respectively open and close the intake port 22 and the exhaust port 23 to the combustion chamber 12a.

[0024] The intake port 22 is connected to the intake passage 3 and introduces air supplied from the intake passage 3 into the combustion chamber 12a, while the exhaust port 23 is connected to the exhaust passage 4 and discharges exhaust gas generated in the combustion chamber 12a into the exhaust passage 4. By opening the intake valve 24, a mixture of fuel gas and air can be taken into the combustion chamber 12a via the intake port 22, while by opening the exhaust valve 25, exhaust gas generated in the combustion chamber 12a can be exhausted via the exhaust port 23.

[0025] 1 shows an example in which the intake passage 3 and the intake port 22 are directly connected, but in order to connect the intake passage 3 to each of the intake ports 22 of the multiple cylinders 12, an intake manifold having branch passages branching from the intake passage 3 to the multiple cylinders 12 may be provided between the intake passage 3 and the engine 2. Also, in FIG. 1 shows an example in which the exhaust passage 4 and the exhaust port 23 are directly connected, but in the case of connecting the exhaust passage 4 to each of the exhaust ports 23 of the multiple cylinders 12, an exhaust manifold having branch passages branching from the exhaust passage 4 to the multiple cylinders 12 may be provided between the exhaust passage 4 and the engine 2.

[0026] In each cylinder 12, the gaseous fuel injection unit 6 is provided in the intake port 22 and is controlled by the control unit 5 to inject gaseous fuel supplied from a gaseous fuel tank (not shown) into the intake port 22. A mixture of air supplied from the intake passage 3 and gaseous fuel supplied from the gaseous fuel tank (not shown) is supplied from the intake port 22 to the combustion chamber 12a. The gaseous fuel injection unit 6 is composed of, for example, a gas admission valve, a gas injector, etc. The gaseous fuel injection unit 6 is controlled by the control unit 5 in terms of injection pressure, injection timing, etc. of the gaseous fuel.

[0027] In each cylinder 12, an ignition device 8 is provided in the cylinder head 15. The ignition device 8 is, for example, a micro-pilot type device that injects a small amount of liquid fuel, and is composed of an injector that injects liquid fuel supplied from a liquid fuel tank (not shown) into the combustion chamber 12a below the cylinder head 15. The injection pressure, injection timing, etc. of the liquid fuel of the ignition device 8 are controlled by the control unit 5. Alternatively, the ignition device 8 may be composed of a spark ignition type device using an ignition plug.

[0028] The intake passage 3 is connected to the intake ports 22 of the cylinders 12 of the engine 2, and supplies compressed and cooled air to each cylinder 12 via the intake ports 22. The intake passage 3 may be provided with a supercharger (not shown) that compresses the air flowing through the intake passage 3 and sends it downstream in the intake direction, or an intercooler (not shown) that cools the air flowing through the intake passage 3. An air filter (not shown) that purifies and introduces fresh air may be provided at the upstream end of the intake passage 3 in the intake direction.

[0029] The intake passage 3 is provided with a throttle valve 7 for adjusting the amount of intake air sent to the intake port 22. The throttle valve 7 is controlled by the control unit 5 to adjust its opening, and by adjusting the amount of intake air sent to the intake port 22 according to the opening of the throttle valve 7, it is possible to adjust the excess air ratio (the proportion of intake air in the mixture) of the mixture of gaseous fuel and air injected from the intake port 22 into the combustion chamber 12a. In other words, by adjusting the opening of the throttle valve 7, it is possible to adjust the flow rate of air supplied from the intake passage 3 to the intake port 22.

[0030] The exhaust passage 4 is connected to an exhaust port 23 of each cylinder 12 of the engine 2, and exhaust gas generated in each cylinder 12 is discharged through the exhaust port 23. An air-fuel ratio sensor 20 that detects the air-fuel ratio of the exhaust gas is provided in the exhaust passage 4, and the air-fuel ratio sensor 20 transmits the detection result to the control unit 5.

[0031] The control unit 5 is a computer such as an ECU (Engine Control Unit) that controls the operation of the engine 2, and includes a CPU, ROM, RAM, etc., and is configured to control each part of the engine 2. The control unit 5 may store various programs for controlling the engine 2, and control the engine 2 by reading and executing the programs.

[0032] In the engine device 1, the ignition device 8 is normally operated at the ignition timing set by the control unit 5, and for example, liquid fuel is injected into the combustion chamber 12a at a predetermined liquid fuel injection timing (injection timing), thereby igniting the gaseous fuel inside the combustion chamber 12a and starting combustion. However, if an abnormality occurs, such as the inside of the combustion chamber 12a becoming excessively high temperature or pressure, the gaseous fuel inside the combustion chamber 12a may self-ignite before the ignition timing (liquid fuel injection timing), causing abnormal combustion such as pre-ignition.

[0033] Furthermore, when operating the engine device 1, in terms of the relationship between the ignition timing (liquid fuel injection timing) of the combustion chamber 12a and the excess air ratio of the mixture (the ratio of intake air to fuel in the mixture) injected into the combustion chamber 12a, the engine device 1 can be operated within an operable region 30 as shown in FIG. 2, but outside the operable region 30, there is a high possibility that dangerous combustion will occur in the combustion chamber 12a, and the engine device 1 cannot be operated.

[0034] Furthermore, near the edges of the operable region 30, there is a high possibility that abnormal combustion such as pre-ignition will occur in the engine 2, even within the range of the operable region 30. For example, near a first edge 31 on the side where the excess air ratio is relatively high in the operable region 30, there is a high possibility that pre-ignition and backfire will occur as abnormal combustion, and near a second edge 32 on the side where the excess air ratio is relatively low, there is a high possibility that pre-ignition and knocking will occur as abnormal combustion.

[0035] 3 shows the results of monitoring the frequency of abnormal combustion that occurs when the engine device 1 is operated within the operable range 30, with the frequency of abnormal combustion increasing near the first edge 31 and the second edge 32 of the operable range 30. FIG 4 shows the results of monitoring the intensity of abnormal combustion that occurs when the engine device 1 is operated within the operable range 30, with the intensity of abnormal combustion increasing near the first edge 31 and the second edge 32 of the operable range 30.

[0036] However, in the operable region 30, the distribution of the frequency of occurrence of abnormal combustion differs from the distribution of the intensity of occurrence of abnormal combustion. Therefore, when abnormal combustion in the engine 2 is detected, it is difficult to determine what type of abnormal combustion is occurring even if the excess air ratio or the ignition timing is referred to, and it is difficult to appropriately determine a suppression method for suppressing abnormal combustion. Moreover, it is difficult to determine what type of abnormal combustion is occurring even if only the frequency of occurrence of abnormal combustion or only the intensity of occurrence of abnormal combustion is referred to, and it is difficult to appropriately determine a suppression method for suppressing abnormal combustion.

[0037] Therefore, in the present invention, the control unit 5 detects abnormal combustion occurring in the combustion chamber 12a, monitors the frequency and intensity of occurrence of the abnormal combustion, and determines a suppression method for suppressing the abnormal combustion depending on the frequency and intensity of occurrence.

[0038] Specifically, first, the control unit 5 detects abnormal combustion that occurs in the engine 2 after the engine device 1 starts operating. For example, the control unit 5 detects the in-cylinder pressure of the cylinder 13 by the pressure sensor 19, monitors the ignition timing (liquid fuel injection timing) of the ignition device 8, and determines that pre-ignition has occurred when the in-cylinder pressure exceeds a predetermined in-cylinder pressure threshold value before the ignition timing.

[0039] Furthermore, the control unit 5 detects the rotation angle of the crankshaft 17 by the angle sensor 18, and calculates the rotation speed of the engine 2 based on the rotation angle. The control unit 5 calculates the occurrence frequency of abnormal combustion as the proportion of cycles determined to be pre-ignition among multiple cycles, based on the rotation speed of the engine 2 in a predetermined period and the number of abnormal combustions that occurred in the predetermined period.

[0040] In addition, the control unit 5 detects the internal pressure of the combustion chamber 12a due to pre-ignition, that is, the increase in the cylinder pressure of the cylinder 13, as the occurrence intensity of abnormal combustion (pre-ignition intensity). For example, the control unit 5 detects the maximum cylinder pressure of the cylinder 13 by the pressure sensor 19 during normal operation of the engine 2, and obtains the most frequent value of the maximum cylinder pressure during normal combustion based on the result. In addition, the control unit 5 detects the maximum cylinder pressure of the cylinder 13 by the pressure sensor 19 when pre-ignition occurs in the engine 2, and obtains the most frequent value of the maximum cylinder pressure during pre-ignition. Then, the control unit 5 calculates the occurrence intensity Int of abnormal combustion from the average difference between the maximum cylinder pressure Pmax1 during pre-ignition and the most frequent value Pmax2 of the maximum cylinder pressure during normal combustion, as shown in the following formula (1). In formula (1), n ​​indicates the number of pre-ignition cycles, and Pmax1(k) indicates the maximum cylinder pressure during pre-ignition in the kth cycle.

[0041]

number

[0042] The control unit 5 performs condition judgment using a matrix, a flow chart, etc. according to the occurrence frequency and occurrence intensity of abnormal combustion detected as described above, and determines a suppression method for suppressing abnormal combustion. The control unit 5 stores a program for performing condition judgment of the occurrence frequency and occurrence intensity of abnormal combustion, and may determine the suppression method by reading and executing this program.

[0043] FIG. 5 shows a selection matrix of suppression methods for the relationship between the frequency and intensity of abnormal combustion. According to the condition judgment such as this selection matrix, when the frequency of abnormal combustion is high and the intensity of abnormal combustion is high in the first region 41, the control unit 5 controls to enrich the gaseous fuel and advance the ignition timing (liquid fuel injection timing). At this time, the control unit 5 may compare the frequency of abnormal combustion with a predetermined frequency threshold to judge whether it is high or low, and may compare the intensity of abnormal combustion with a predetermined intensity threshold to judge whether it is high or low. The frequency threshold and intensity threshold may be prepared according to the model and environment of the engine device 1. The control unit 5 may control at least one of the ignition timing of the gaseous fuel and the excess air ratio of the intake air in the mixture of the gaseous fuel and the intake air. For example, the control unit 5 controls the ignition device 8 to advance the ignition timing, and controls the gaseous fuel injection unit 6 and the throttle valve 7 to lower the excess air ratio and enrich the gaseous fuel.

[0044] Furthermore, when the abnormal combustion occurs in a second region 42 where the frequency of occurrence is low and the intensity of occurrence is high, the control unit 5 controls the gaseous fuel to be lean. At this time, the control unit 5 may control at least one of the excess air ratio of the intake air in the mixture of the gaseous fuel and the intake air, and the shutoff of the gaseous fuel. For example, the control unit 5 controls the gaseous fuel injection unit 6 and the throttle valve 7 to reduce the excess air ratio and make the gaseous fuel lean.

[0045] When the occurrence frequency of abnormal combustion is low and the occurrence intensity is low in the third region 43, the control unit 5 determines that the operation of the engine 2 is in a safe state and therefore does not need to suppress abnormal combustion. When the occurrence frequency of abnormal combustion is high and the occurrence intensity is high, exceeding the first region 41 and the second region 42, the control unit 5 determines that the operation of the engine 2 is in an inoperable state beyond the operable region 30 and therefore does not suppress abnormal combustion and may, for example, stop the operation of the engine 2.

[0046] As described above, according to this embodiment, the engine device 1, which is driven by injecting gaseous fuel into the combustion chamber 12a of the engine 2, detects abnormal combustion that occurs in the combustion chamber 12a, monitors the frequency and intensity of the abnormal combustion, and determines and executes a suppression method for suppressing the abnormal combustion in accordance with the frequency and intensity of the abnormal combustion.

[0047] In other words, the control method of the engine device 1 that drives the engine 2 by injecting gaseous fuel into the combustion chamber 12a detects abnormal combustion occurring in the combustion chamber 12a, monitors the frequency and intensity of the abnormal combustion, and determines and executes a suppression method for suppressing the abnormal combustion according to the frequency and intensity of the abnormal combustion. Note that the control method may be executed by the control unit 5, and may be configured by a program, for example.

[0048] In the engine device 1, when abnormal combustion is judged based only on the frequency of occurrence, abnormal combustion with a low occurrence frequency will be overlooked even if the intensity of occurrence is extremely high. In addition, in the engine device 1, when abnormal combustion is judged based only on the intensity of occurrence, abnormal combustion with a low occurrence frequency will be overlooked even if the frequency of occurrence is extremely high. In either case, there is a risk that the overlooked abnormal combustion will cause extremely serious damage to the engine 2. In addition, there are a wide variety of combinations of the frequency and intensity of occurrence of abnormal combustion, and the optimal method for suppressing abnormal combustion differs depending on the combination of the frequency and intensity of occurrence.

[0049] In contrast, the engine device 1 of the present embodiment can more appropriately determine a method of suppressing abnormal combustion by simultaneously referring to both the frequency and intensity of abnormal combustion, and can more appropriately suppress abnormal combustion using that suppression method, thereby enabling the engine 2 to be operated more safely.

[0050] Furthermore, according to this embodiment, the engine device 1 controls, as a suppression method, at least one of the ignition timing of the gaseous fuel, the excess air ratio of the intake air in the mixture of the gaseous fuel and the intake air, and the cutoff of the gaseous fuel.

[0051] This enables the engine device 1 to specifically determine a method for suppressing abnormal combustion according to the frequency and intensity of occurrence of abnormal combustion, and also to optimally select whether to use one method for suppressing abnormal combustion alone or in combination.

[0052] Furthermore, according to this embodiment, the engine device 1 determines the suppression method based on condition judgments of matrices, flow charts, etc., which indicate the relationship between the frequency and intensity of abnormal combustion and the suppression method of abnormal combustion.

[0053] As a result, the engine device 1 can easily and easily determine and control the method of suppressing abnormality determination by using condition determination such as a matrix or a flow chart. In addition, the control data input to the control unit 5 can be simplified and easily handled.

[0054] Furthermore, according to this embodiment, the engine device 1 determines a method of suppressing abnormal combustion based on a comparison between the frequency of occurrence of abnormal combustion and a predetermined frequency threshold value, and a comparison between the intensity of occurrence of abnormal combustion and a predetermined intensity threshold value.

[0055] This enables the engine device 1 to clearly identify and determine the state of frequency and intensity of abnormal combustion, and to select a method of suppressing abnormal combustion that is more suitable for the state of frequency and intensity of abnormal combustion.

[0056] In the above embodiment, an example has been described in which, in the engine device 1, when the control unit 5 performs a condition determination of the frequency and intensity of abnormal combustion, it determines whether the frequency is low or high, and also whether the intensity is low or high. However, the present invention is not limited to this example.

[0057] In another example, the control unit 5 may determine the frequency and intensity of abnormal combustion into three or more stages, respectively, and determine a method for suppressing abnormal combustion according to the determination result. Furthermore, when controlling the ignition timing of the gaseous fuel or the excess air ratio of the intake air as a method for suppressing abnormal combustion, the control unit 5 may determine the control amount of the ignition timing or the excess air ratio according to the frequency and intensity of abnormal combustion. Alternatively, in another example, the control unit 5 may use a formula for calculating the control amount of the ignition timing or the excess air ratio based on the frequency and intensity of abnormal combustion.

[0058] In the above embodiment, the engine device 1 is a gas engine configured to be driven by supplying gaseous fuel such as hydrogen into the combustion chamber 12a of the engine 2, but the present invention is not limited to this example. In another example, the engine device 1 may be configured as a dual-fuel engine that is driven by supplying at least one of gaseous fuel such as hydrogen and liquid fuel such as diesel or heavy oil into the combustion chamber 12a of the engine 2. In this case, the engine device 1 supplies gaseous fuel by the gaseous fuel injection unit 6 and supplies liquid fuel by a liquid fuel injection unit such as a micro-pilot type ignition device 8.

[0059] The dual-fuel engine unit 1 operates in either a gas mode in which gas fuel is fed into the combustion chamber 12a to drive the engine, or a diesel mode in which liquid fuel is fed into the combustion chamber 12a to drive the engine, and also operates in a multi-combustion mode in which both gas fuel and liquid fuel are fed into the combustion chamber 12a to drive the engine.

[0060] In the dual-fuel engine device 1, the control unit 5 controls at least one of the following abnormal combustion suppression methods, which are determined according to the frequency and intensity of abnormal combustion: the ignition timing of the gaseous fuel, the excess air ratio of the mixture, shutting off the gaseous fuel, and switching to driving with both gaseous fuel and liquid fuel (mixed combustion mode) or driving with only liquid fuel (diesel mode).

[0061] 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 the engine device and its control method involving such modifications are also included in the technical concept of the present invention.

[0062] [Appendix to the invention] The following will provide an overview of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0063] <Appendix 1> An engine device driven by gaseous fuel, Detecting abnormal combustion occurring in a combustion chamber and monitoring the frequency and intensity of occurrence of said abnormal combustion; An engine system comprising: an engine control unit that determines a suppression method for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity.

[0064] <Appendix 2> The engine device described in Appendix 1, characterized in that the suppression method includes controlling at least one of the ignition timing of the gaseous fuel, the excess air ratio of the intake air in a mixture of the gaseous fuel and the intake air, and cutting off the gaseous fuel.

[0065] <Appendix 3> The engine device according to claim 1 or 2, wherein the suppression method is determined based on a condition determination indicating a relationship between the occurrence frequency and the occurrence intensity and the suppression method.

[0066] <Appendix 4> 4. The engine device according to claim 1, wherein the suppression method is determined based on a frequency threshold value of the occurrence frequency and an intensity threshold value of the occurrence intensity.

[0067] <Appendix 5> An engine device that is driven by at least one of gas fuel and liquid fuel, Detecting abnormal combustion occurring in a combustion chamber when the engine is driven by the gaseous fuel, and monitoring the frequency and intensity of the abnormal combustion; determining a suppression method for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity; The engine device is characterized in that the suppression method includes controlling at least one of the ignition timing of the gaseous fuel, the excess air ratio of the intake air in a mixture of the gaseous fuel and the intake air, cutting off the gaseous fuel, and switching to drive using both the gaseous fuel and the liquid fuel or drive using only the liquid fuel.

[0068] <Appendix 6> The engine device according to claim 5, wherein the suppression method is determined based on a condition determination indicating a relationship between the occurrence frequency and the occurrence intensity and the suppression method.

[0069] <Appendix 7> The engine device according to claim 5 or 6, wherein the suppression method is determined based on a frequency threshold of the occurrence frequency and an intensity threshold of the occurrence intensity.

[0070] <Appendix 8> A method for controlling a gaseous fuel-driven engine device, comprising: Detecting abnormal combustion occurring in a combustion chamber and monitoring the frequency and intensity of occurrence of said abnormal combustion; A control method for an engine system, comprising determining a suppression technique for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity.

[0071] <Appendix 9> 9. The control method for an engine device according to claim 8, characterized in that the suppression method includes controlling at least one of an ignition timing of the gaseous fuel, an excess air ratio of the intake air in a mixture of the gaseous fuel and the intake air, and a cutoff of the gaseous fuel.

[0072] <Appendix 10> 10. The control method for an engine device according to claim 8, wherein the suppression method is determined based on a condition determination indicating a relationship between the occurrence frequency and the occurrence intensity and the suppression method.

[0073] <Appendix 11> 11. The control method for an engine device according to any one of claims 8 to 10, further comprising determining the suppression technique based on a frequency threshold value of the occurrence frequency and an intensity threshold value of the occurrence intensity. [Explanation of symbols]

[0074] 1 Engine unit 2 Engine 3 Intake passage 4 Exhaust passage 5. Control Unit 6 Gas fuel injection section 7 Throttle valve 8 Igniter 11 Cylinder block 12 cylinders 12a Combustion chamber 13 Cylinder 14 Piston 15 Cylinder head 16 Connecting rod 17 Crankshaft 18 Angle Sensor 19 Pressure Sensor 20 Air-fuel ratio sensor 22 Intake port 23 Exhaust port 24 Intake valve 25 Exhaust valve

Claims

1. An engine device driven by gaseous fuel, Detecting abnormal combustion occurring in a combustion chamber and monitoring the frequency and intensity of occurrence of said abnormal combustion; An engine system comprising: an engine control unit that determines a suppression method for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity.

2. 2. The engine device according to claim 1, wherein the suppression method includes controlling at least one of an ignition timing of the gaseous fuel, an excess air ratio of the intake air in a mixture of the gaseous fuel and the intake air, and blocking the gaseous fuel.

3. 2. The engine device according to claim 1, wherein the suppression method is determined based on a condition determination indicating a relationship between the occurrence frequency and the occurrence intensity and the suppression method.

4. The engine device according to claim 1 , wherein the suppression method is determined based on a frequency threshold value of the occurrence frequency and an intensity threshold value of the occurrence intensity.

5. An engine device that is driven by at least one of gas fuel and liquid fuel, Detecting abnormal combustion occurring in a combustion chamber when the engine is driven by the gaseous fuel, and monitoring the frequency and intensity of the abnormal combustion; determining a suppression method for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity; The engine device is characterized in that the suppression method controls at least one of the following: ignition timing of the gaseous fuel, the excess air ratio of the intake air in a mixture of the gaseous fuel and the intake air, blocking of the gaseous fuel, and switching to drive using both the gaseous fuel and the liquid fuel or drive using only the liquid fuel.

6. A method for controlling a gaseous fuel-driven engine device, comprising: Detecting abnormal combustion occurring in a combustion chamber and monitoring the frequency and intensity of occurrence of said abnormal combustion; A control method for an engine system, comprising determining a suppression technique for suppressing the abnormal combustion in accordance with the occurrence frequency and the occurrence intensity.

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