Control device, control method, and program

Abstract

The present invention provides a control device that can suppress the occurrence of abnormalities when transitioning between any operating modes. [Solution] The control device includes a control unit that, when transitioning the engine's operating mode from a first operating mode to a second operating mode, transitions from the first operating mode to a safe mode, which is a common operating mode designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.

Description

Technical Field

[0001] The present disclosure relates to a control device, a control method, and a program.

Background Art

[0002] When changing set values such as the ignition timing and air-fuel ratio of an engine along with changes in fuel properties such as fuel switching, if the timing and speed of the change in fuel properties and the set values do not match, the set values become inappropriate for the constantly changing fuel properties, increasing the likelihood of abnormal combustion such as knocking and premature ignition. In particular, when switching between natural gas and hydrogen or hydrogen-mixed fuels, abnormal combustion such as knocking and premature ignition is likely to occur due to the influence of hydrogen, which has good ignitability and a high combustion speed. [[ID=I3]]

[0003] However, since the fuel properties at the engine inlet change constantly depending on the operating load, plant layout, etc., it is difficult to uniquely determine the appropriate value for the fuel properties at any given time. As a countermeasure, a method of monitoring the fuel properties at the engine inlet can be mentioned, but this leads to higher costs due to an increase in equipment.

[0004] Also, in case the adjustment of set values such as ignition timing and air-fuel ratio does not go well, if an avoidance mode for abnormal conditions is provided for each type of abnormality, the number of operating modes increases, the control becomes complicated, and in addition, an increase in set values makes it easy to induce setting mistakes during adjustment.

[0005] Regarding the control when fuel properties change, Patent Document 1 discloses control for reducing NOx emissions by first starting intake air cooling, then adjusting the intake air amount, and finally ending the switching between the first combustion mode with a lean fuel and the second combustion mode with a stoichiometric air-fuel ratio when transitioning the operating mode between the first combustion mode with a lean fuel and the second combustion mode with a stoichiometric air-fuel ratio. However, Patent Document 1 does not disclose control for suppressing the occurrence of abnormalities in the transient state when transitioning between any operating modes.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-34303 [Overview of the project] [Problems that the invention aims to solve]

[0007] There is a need for technology that can suppress the occurrence of abnormalities when transitioning between any operating modes.

[0008] This disclosure provides a control device, a control method, and a program that can solve the above-mentioned problems. [Means for solving the problem]

[0009] The control device of this disclosure includes a control unit that, when transitioning the engine's operating mode from a first operating mode to a second operating mode, transitions from the first operating mode to a safe mode, which is a common operating mode in which the control parameter settings are designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.

[0010] The control method of the present disclosure is such that when the engine control device transitions the engine's operating mode from a first operating mode to a second operating mode, it transitions from the first operating mode to a safe mode, which is a common operating mode for which the control parameter settings are designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.

[0011] The program of this disclosure causes the computer to function as a means for transitioning the engine's operating mode from a first operating mode to a second operating mode, by transitioning from the first operating mode to a safe mode, which is a common operating mode designed to prevent malfunctions, and then transitioning from the safe mode to the second operating mode. [Effects of the Invention]

[0012] According to the control device, gas engine, and control method described above, it is possible to suppress the occurrence of abnormalities during transient states when transitioning between any operating modes. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of the gas engine system according to the embodiment. [Figure 2] This diagram illustrates the transitions between conventional operating modes. [Figure 3] This diagram illustrates the transitions between operating modes according to the embodiment. [Figure 4] This diagram illustrates an example of conventional operating mode transition control. [Figure 5] This figure illustrates an example of operation mode transition control according to the embodiment. [Figure 6] This figure illustrates an example of an operating mode transition according to the embodiment. [Figure 7] This is a first flowchart showing an example of operation mode transition control according to the embodiment. [Figure 8] This is a second flowchart showing an example of the operation mode transition control according to the embodiment. [Figure 9] This figure shows an example of the hardware configuration of the control device according to the embodiment. [Modes for carrying out the invention]

[0014] <Embodiment> (composition) The control method for transitioning between operating modes in this disclosure will be described below with reference to the figures. Figure 1 is a schematic diagram of the engine system 1 according to this embodiment. The engine system 1 comprises a hydrogen mixing device 2, an engine 3, and a control device 10 that controls the engine 3.

[0015] The hydrogen mixing device 2 generates a mixed fuel by mixing hydrogen with natural gas such as city gas, and supplies the generated mixed fuel to the engine 3. The concentration of hydrogen in the mixed fuel is called the mixing ratio. The hydrogen mixing device 2 controls the mixing ratio to a desired value based on the load of the engine 3 and a fuel switching command output from a controller (not shown). The hydrogen mixing device 2 can also supply natural gas alone or hydrogen alone to the engine 3 as fuel gas.

[0016] The engine 3 is a gas engine that uses a mixed fuel obtained by mixing hydrogen with natural gas, natural gas without hydrogen, or pure hydrogen as fuel gas. The engine 3 mixes the fuel gas supplied through the fuel supply line L1 from the hydrogen mixing device 2 and the air supplied through the air supply line L2 to generate an air-fuel mixture, and outputs power by burning the generated air-fuel mixture. The engine 3 includes a fuel supply line L1, an air supply line L2, an intake line L3 that is connected to the lines L1 and L2 and generates an air-fuel mixture, a sub-fuel line L4 connected to the fuel supply line L1, an exhaust line L5, one or more cylinders 4, a piston 5 provided for each cylinder 4, a combustion chamber 6, a spark plug 7, a sub-chamber (sub-combustion chamber) 8, and the like. The air-fuel mixture is supplied to the cylinder 4 through the intake line L3, and the fuel gas is supplied to the sub-chamber 8 through the sub-fuel line L4. The flame formed by igniting the spark plug 7 in the sub-chamber 8 is blown into the combustion chamber 6, and the air-fuel mixture is burned in the combustion chamber 6. The exhaust gas after combustion is exhausted through the exhaust line L5. A sensor C2 for measuring the temperature of the exhaust gas and a sensor C3 for detecting the components of the exhaust gas are provided in the exhaust line L5. Further, a sensor C1 for measuring the pressure in the cylinder 4 is provided in the cylinder 4. The information measured by the sensors C1, C2, and C3 is output to the control device 10.

[0017] The control device 10 controls the engine 3. The control device 10 includes a signal acquisition unit 11, a determination unit 12, and a control unit 13. The signal acquisition unit 11 acquires the information measured by each of the sensors C1 to C3. The signal acquisition unit 11 also acquires a fuel switching command, a set value of the mixing ratio in the hydrogen mixing device 2, a measured value of the mixing ratio, and the like.

[0018] The determination unit 12 determines whether or not to transition the operation mode. For example, when a change in the mixing ratio (change in combustion characteristics) occurs, the determination unit 12 determines to transition the operation mode to an operation mode corresponding to the hydrogen mixing ratio. In the present embodiment, when transitioning from the first operation mode to the second operation mode, the set value of the control parameter is designed so that no abnormality occurs regardless of the operation mode from which the transition is made, and the transition to the second operation mode is performed via a common operation mode (referred to as a safe mode). The determination unit 12 determines the timing of transitioning from this safe mode to the second operation mode. For example, it may be determined that the transition to the second operation mode is made when the fuel switching is completed, or it may be determined that the transition to the second operation mode is made when the state is stable after the fuel switching is completed. Further, regardless of the transition of the operation mode, the determination unit 12 determines whether or not abnormal combustion or the like has occurred during operation, and if an abnormality has occurred, determines to transition from the currently executing operation mode to the safe mode. After transitioning to the safe mode, it is determined whether or not the abnormality has been resolved, and if the abnormality has been resolved, it is determined to return to the original operation mode.

[0019] Regarding this abnormality determination, the determination unit 12 determines the combustion state of the engine 3. For example, when the pressure measured by the sensor C1 or the pressure change per unit time deviates from the normal range, the determination unit 12 determines that abnormal combustion such as knocking has occurred, and determines that the combustion is stable when they are within the normal range. Similarly, when the temperature of the exhaust gas measured by the sensor C2 or the temperature change per unit time deviates from the normal range, the determination unit 12 determines that abnormal combustion has occurred, and determines that the combustion is stable when they are within the normal range. Further, when the components, component ratios, and component changes of the exhaust gas measured by the sensor C3 deviate from the normal range, the determination unit 12 determines that abnormal combustion has occurred, and determines that the combustion is stable when they are within the normal range.

[0020] The control unit 13 operates the engine 3 by performing combustion control and air-fuel ratio control. In combustion control, it controls the engine speed and load of the engine 3 to target values. For example, the control unit 13 controls the flow rate of fuel gas supplied to the sub-chamber 8 by controlling valve V3 etc. provided in the sub-fuel line L4, and advances or delays the ignition timing of the spark plug 7 and the fuel gas supply timing of injecting fuel gas from the fuel supply line L1 to the intake line L3. In air-fuel ratio control, in order to maintain a constant air-fuel ratio in the combustion chamber of the engine 3, it performs feedback control by controlling valves V1, V2 etc. provided in the lines L1 to L3 that flow into the combustion chamber so that the air-fuel ratio reaches the target value.

[0021] Furthermore, the control unit 13 controls the transition of the engine 3's operating mode based on the determination of the determination unit 12. The operating modes include, for example, an operating mode for operating with natural gas alone (referred to as operating mode 1), an operating mode for operating with a mixed fuel of natural gas and hydrogen (referred to as operating mode 2), an operating mode for operating with hydrogen gas alone (referred to as operating mode 3), and a low NOx mode for reducing NOx in the exhaust gas. For example, the control unit 13 obtains the set value of the mixing ratio from the hydrogen mixing device 2, and when the set value of the mixing ratio changes from 50% to 0%, it decides to operate in operating mode 1 and changes the operating mode of the engine 3 from operating mode 2 to operating mode 1. Similarly, when the set value of the mixing ratio changes from 0% to 50%, the control unit 13 changes the operating mode from operating mode 1 to operating mode 2. Also, when operation in low NOx mode is instructed, the control unit 13 changes the operating mode from another operating mode to low NOx mode.

[0022] When changing the operating mode, the control unit 13 changes the set values ​​of control parameters such as load, rotational speed, ignition timing, ignition energy, air-fuel ratio, intake air temperature, fuel gas flow rate, fuel gas supply pressure, fuel gas temperature, fuel gas supply timing, flow rate of sub-chamber fuel gas supplied to sub-chamber 8, sub-chamber fuel gas supply pressure, sub-chamber fuel gas temperature, sub-chamber fuel gas supply timing, coolant temperature, coolant pressure, coolant flow rate, lubricating oil temperature, lubricating oil pressure, lubricating oil flow rate, and valve timing, as well as the set values ​​of other parameters that directly or indirectly affect these parameters.

[0023] Furthermore, when changing the hydrogen concentration during operation mode switching, the control unit 13 also switches the crankcase purge of engine 3 ON / OFF. This is because if the fuel gas contains hydrogen, there is a possibility that unburned gas may ignite in the crankcase, and purging is necessary to ensure safety. For example, when operating in operation mode 2, the control unit 13 turns the purge ON. When transitioning from operation mode 2 to operation mode 1, the control unit 13 turns the purge ON after transitioning to safe mode and until the transition from safe mode to operation mode 1 begins (until the fuel switching is complete, or for a while after the switching is complete), and then turns the purge OFF. Similarly, when transitioning from operation mode 1 to operation mode 2, the control unit 13 turns the purge OFF while operation mode 1 is running, and turns the purge ON when transitioning to safe mode (at the same time as the start of fuel switching).

[0024] Next, we will explain the method of transitioning between operating modes. Figure 2 shows an example of a conventional operating mode transition. In conventional operating mode transitions, transitions between operating modes occur directly, such as from operating mode A to normal mode B, and from normal mode B to operating mode C. When an operating mode transition involves a change in fuel properties (for example, a change in hydrogen concentration), if the change in the set value of the control parameter does not correctly follow the change in fuel properties at the engine inlet, abnormal combustion such as knocking or premature ignition may occur. Generally, for each type of abnormal combustion that occurs, an avoidance mode (an avoidance mode is a type of operating mode) such as abnormal avoidance 1 and abnormal avoidance 2 is prepared. If abnormal combustion occurs during an operating mode transition, the system transitions to the avoidance mode corresponding to the abnormal combustion, and once the abnormal condition is resolved, it returns to the original operating mode or the target operating mode. As shown in Figure 2, in conventional operating mode transitions, the number of operating modes (including avoidance modes) and the transition patterns (arrows in Figure 2) increase, making the control more complex. Also, the increase in set values ​​makes it easier to induce setting errors during adjustment. Therefore, in this embodiment, a safe mode is provided, which is a common avoidance mode that can reliably avoid abnormalities. When transitioning to a different operating mode, the system always first switches to safe mode before transitioning to or returning to the desired operating mode. In conventional control, avoidance modes were provided for each type of abnormality, but these are unified into a single safe mode. The settings for the control parameters of safe mode are considered and designed so that abnormalities can be avoided regardless of the operating mode from which the system is transitioned, or so that even if an abnormality occurs during operation in such an operating mode, the system will be directed toward resolving that abnormality (so that it functions as an avoidance mode for all abnormalities).

[0025] Figure 3 shows an example of the operating mode transition in this embodiment. In this embodiment, when transitioning from normal mode B to operating mode A, the system transitions from normal mode B to safe mode, and then from safe mode to operating mode A. For example, in the case of an operating mode transition involving fuel switching (such as changing the fuel properties from pure natural gas to a hydrogen-blended fuel), the system transitions from normal mode B to safe mode at the start of fuel switching. Then, once fuel switching is complete, the system transitions from safe mode to operating mode A. The transition from safe mode to operating mode A may occur simultaneously with the completion of fuel switching, or it may be performed after a certain period of time has elapsed since fuel switching to ensure a safer transition. Safe mode is an operating mode in which abnormalities can be reliably avoided. Therefore, in safe mode, control parameters (such as ignition timing retardation and air-fuel ratio increase) are changed to weaken combustion within a range that does not cause misfires. When transitioning from safe mode to another operating mode, the system controls the system to strengthen combustion. In this case, in order to suppress abnormal combustion caused by sudden changes in control parameter settings, it is preferable to transition from safe mode to the desired operating mode in stages (over a predetermined period of time). For example, the air-fuel ratio can be reduced or the ignition timing advanced gradually. Also, if an abnormality occurs while the system is running in normal mode B or operating mode A, it will switch from those operating modes to a common avoidance mode called safe mode, and return to the original operating mode after the abnormality is resolved. By introducing a common safe mode in this way, stable operation during transient states is ensured. As a result, the operating modes to which the system is transitioned no longer need to consider transitions to other operating modes, and the control parameter settings can be optimized (higher efficiency) for each operating mode.

[0026] Next, we will explain the control process when transitioning between operating modes with specific examples. This explanation will use the example of a transition from operating mode 2, where the hydrogen concentration in the fuel gas at the engine 3 inlet is 50%, to operating mode 1, where the hydrogen concentration in the fuel gas at the engine 3 inlet is 0%. First, please refer to Figure 4 to explain the conventional control. Figure 41, upper part of Figure 4, shows the change in hydrogen concentration in the fuel gas. The vertical axis of Figure 41 represents the hydrogen concentration, and the horizontal axis represents the time elapsed since the fuel switching command was output. Figure 42, lower part of Figure 4, shows the change in ignition timing of the spark plug 7 as an example of a control parameter. The vertical axis of Figure 42 represents the ignition timing, and the horizontal axis represents the time elapsed since the fuel switching command was output. Because there is a distance from the hydrogen mixing device 2 to the engine 3, there is a time lag between the output of the fuel switching command and the actual start of the change in fuel properties at the engine 3 inlet. Also, since the hydrogen concentration is not switched from 50% to 0% immediately after the fuel switching command is output, it takes time for the fuel properties at the engine 3 inlet to completely switch from the state assumed in operating mode 2 to the state assumed in operating mode 1. In other words, the hydrogen concentration at the engine 3 inlet gradually decreases from 50% to 0% with a slight delay after the fuel switching command is output. Conventional control systems gradually retard the ignition timing in accordance with this decrease in hydrogen concentration. In this case, for example, moment-by-moment set values, as shown by the solid line in Figure 42, are prepared in advance, and the ignition timing is controlled according to these set values. However, if the actual appropriate value for the ignition timing according to the moment-by-moment fuel properties follows the progression shown by the dashed line in Figure 42, the moment-by-moment ignition timing will shift towards the advanced side compared to the appropriate value, raising concerns about abnormal combustion such as knocking.

[0027] In contrast, in this embodiment, the transition from operating mode 1 to operating mode 2 is performed by the control shown in Figure 5. The vertical and horizontal axes in upper Figure 51 and lower Figure 52 of Figure 5 are the same as in Figures 41 and 42, respectively. Also, Figure 51 shows the same hydrogen concentration transition as in Figure 41. In this embodiment, if a fuel switching command is output during operation in operating mode 2, the system transitions to safe mode instead of operating mode 1. At this time, the control unit 13 changes the control parameters in the following order: (1) retard the ignition timing. (2) increase the air-fuel ratio. (3) retard the fuel gas supply timing. (4) decrease the sub-chamber fuel gas flow rate to the sub-chamber 8. The extent to which the ignition timing and fuel gas supply timing are retarded, and the extent to which the air-fuel ratio and fuel gas flow rate are set, are predetermined so that no problems occur regardless of the operating mode or abnormal condition from which the system transitions (a common avoidance mode that can avoid abnormalities). By changing the setting values ​​of the control parameters in the above order, stable combustion can be maintained while avoiding transient excessive increases in cylinder pressure. The dashed line in Figure 52 represents the appropriate ignition timing value at each moment. The solid line in Figure 52, from 0 to 6 seconds, represents the ignition timing setting value in safe mode.

[0028] Furthermore, when transitioning from safe mode to a predetermined operating mode, the control unit 13 changes the control parameters in the following order: (1) Increase the flow rate of the sub-chamber fuel gas supplied to the sub-chamber 8. (2) Advance the fuel gas supply timing. (3) Decrease the air-fuel ratio. (4) Advance the ignition timing. By controlling in this order, stable combustion can be maintained while avoiding the occurrence of abnormal combustion. In Figure 52, the solid line from 6 seconds onwards represents the ignition timing setting when transitioning from safe mode to operating mode 2. As mentioned above, it is preferable to transition from safe mode to other operating modes in stages. The gradual advancement of the ignition timing from 6 seconds onwards in Figure 52 is an example of a staged transition.

[0029] Furthermore, when transitioning from operating mode 1 (0% hydrogen concentration) to safe mode, and when transitioning from operating mode 2 (50% hydrogen concentration) to safe mode, the range of change in the control parameter settings during the transition to safe mode is larger, which may lead to unstable combustion or decreased efficiency. For example, comparing the control parameters of operating modes 1 and 2, operating mode 2 has a retarded ignition timing and a larger air-fuel ratio compared to operating mode 1. Therefore, when transitioning from operating mode 1 to safe mode, which has an even retarded ignition timing and a larger air-fuel ratio, the range of change in the ignition timing and air-fuel ratio settings will be larger than when transitioning from operating mode 2 to safe mode. In this case, there is a concern about unstable combustion and decreased efficiency. Also, if abnormal combustion occurs during operation in operating mode 2, and the system switches to safe mode and then returns, the time it takes to stabilize operation after switching between operating mode 2 and safe mode will be longer due to the larger difference in setting values, resulting in a longer operating time in an inefficient state. To address such situations, instead of having a single unified safe mode, two types of safe modes may be provided: Safe Mode 1 for use when transitioning from Operating Mode 1, and Safe Mode 2 for use when transitioning from Operating Mode 2. When comparing the control parameter settings of Safe Mode 1 and Safe Mode 2, the settings for Safe Mode 1 are designed to be relatively close to those of Operating Mode 1, and the settings for Safe Mode 2 are designed to be relatively close to those of Operating Mode 2. By providing multiple safe modes depending on the operating conditions (e.g., fuel properties), it is possible to suppress excessive efficiency degradation and driving stabilization caused by avoidance actions to switch to safe mode.

[0030] Figure 6 shows an example of the operating mode transitions when two types of safe modes are provided. For example, when transitioning from operating mode 1 to operating mode 2, as shown in Figure 6(a), the system transitions from operating mode 1 to safe mode 1, and when conditions such as a predetermined time elapsed or the mixture ratio exceeding a predetermined value are met, it transitions from safe mode 1 to safe mode 2, and when the fuel is switched and the operation stabilizes, it transitions from safe mode 2 to operating mode 2. Similarly, when transitioning from operating mode 2 to operating mode 1, as shown in Figure 6(b), the system transitions from operating mode 2 to safe mode 2, and when predetermined conditions are met, it transitions from safe mode 2 to safe mode 1, and when the fuel is switched and the operation stabilizes, it transitions from safe mode 1 to operating mode 1.

[0031] Furthermore, if an abnormality occurs during operation in operating mode 1, the system will switch from operating mode 1 to safe mode 1, as shown in Figure 6(c), and will return to operating mode 1 once the abnormality is resolved. Similarly, if an abnormality occurs during operation in operating mode 2, the system will switch from operating mode 2 to safe mode 2, as shown in Figure 6(d), and will return to operating mode 2 once the abnormality is resolved.

[0032] (operation) Next, with reference to Figures 7 and 8, the control flow during the transition of operating modes will be explained. Figure 7 shows an example of control when transitioning the operating mode from the first operating mode to the second operating mode. Assume that engine 3 is operating in the first operating mode. First, the determination unit 12 determines whether or not to transition from the first operating mode to the second operating mode (step S1). If the first operating mode is operating mode 1 and the second operating mode is operating mode 2, when the signal acquisition unit 11 acquires a set value or measured value of the hydrogen mixing ratio acquired from the hydrogen mixing device 2 from 0%, the determination unit 12 determines that it will transition from operating mode 1, which corresponds to a mixing ratio of 0%, to operating mode 2. Alternatively, when the signal acquisition unit 11 acquires a fuel switching signal instructing to change the mixing ratio from 0% to 50%, the determination unit 12 determines that it will transition from operating mode 1 to operating mode 2. If there is no change in the mixing ratio, the determination unit 12 determines that it will not transition from operating mode 1 to operating mode 2. Furthermore, for example, if the first operating mode is operating mode 1 and the second operating mode is low NOx mode, when the signal acquisition unit 11 acquires a command signal instructing a switch to low NOx mode, the determination unit 12 determines that a transition to low NOx mode will occur. If no command signal is acquired, the determination unit 12 determines that a transition to low NOx mode will not occur. If it is determined that a transition to the second operating mode will not occur (step S1; No), the determination in step S1 is repeated.

[0033] If the determination unit 12 determines that the system should transition from operating mode 1 to operating mode 2 (step S1; Yes), the control unit 13 transitions from the first operating mode to safe mode (step S2). The control unit 13 changes the settings of the following control parameters in order: (1) retard the ignition timing, (2) increase the air-fuel ratio, (3) retard the fuel gas supply timing, and (4) decrease the flow rate of the sub-chamber fuel gas, and then transitions to safe mode.

[0034] Next, the determination unit 12 determines whether the transition conditions for transitioning from safe mode to operating mode 2 have been met (step S3). For example, when transitioning to operating mode 2, the determination unit 12 determines that the conditions for transitioning from safe mode to operating mode 2 have been met when the mixing ratio of hydrogen obtained from the hydrogen mixing device 2 becomes 50%. Alternatively, it may determine that the conditions for transitioning to operating mode 2 have been met when a predetermined time has elapsed since the mixing ratio became 50%, or it may determine that the transition conditions have been met when the mixing ratio becomes 50% and the combustion state determination result based on sensors C1 to C3 indicates stable combustion. If these transition conditions are not met (step S3; No), the determination unit 12 repeats the determination in step S3 until the transition conditions are met. If the transition conditions are met (step S3; Yes), the control unit 13 transitions from safe mode to the second operating mode (step S4). The control unit 13 changes the settings of the following control parameters in order to transition to the second operating mode: (1) increasing the flow rate of the sub-chamber fuel gas supplied to the sub-chamber 8 in a ramp-like or step-like manner up to the setting value of the second operating mode; (2) advancing the fuel gas supply timing in a ramp-like or step-like manner up to the setting value of the second operating mode; (3) decreasing the air-fuel ratio in a ramp-like or step-like manner up to the setting value of the second operating mode; and (4) advancing the ignition timing in a ramp-like or step-like manner up to the setting value of the second operating mode.

[0035] Furthermore, when changing the hydrogen mixing ratio from 0% to 50%, the safe mode may be divided into two types, and the transitions may occur in the order of operating mode 1, safe mode 1, safe mode 2, and operating mode 2. In this case, the transition between safe mode 1 and safe mode 2 may be configured such that after a predetermined time has elapsed in safe mode 1, the system transitions to safe mode 2, or after the mixing ratio reaches a predetermined value in safe mode 1, the system transitions to safe mode 2. The determination of the conditions for transitioning from safe mode 2 to operating mode 2 may be the same as in step S3.

[0036] Furthermore, in the explanation of Figure 7, the first operating mode was referred to as operating mode 1 and the second operating mode as operating mode 2. However, even if, for example, the first operating mode is operating mode 1 and the second operating mode is operating mode 3 (100% hydrogen), the transition from the first operating mode to the second operating mode can be achieved through similar control.

[0037] Next, referring to Figure 8, we will explain the control flow when an abnormality occurs during operation in a certain operating mode. The determination unit 12 detects an abnormality during the first operating mode (step S11). For example, the determination unit 12 determines the combustion state based on sensors C1 to C3, and if the value measured by any of the sensors or the change in the measured value deviates from the normal range, it determines that an abnormality has occurred (detection of abnormality).

[0038] When an abnormality is detected, the control unit 13 switches from the first operating mode to safe mode (step S12). This process is the same as step S2 in Figure 7.

[0039] Next, the determination unit 12 determines whether the abnormality has been resolved (step S13). For example, the determination unit 12 determines the combustion state based on sensors C1 to C3, and if the values ​​measured by each sensor and the changes in the measured values ​​are all within the normal range, it determines that the abnormality has been resolved. If this condition is not met (step S13; No), the determination unit 12 repeats the determination in step S13 until the condition is met.

[0040] Once the abnormality is resolved (step S13; Yes), the control unit 13 returns from safe mode to the first operating mode (step S14). The control unit 13 returns to the first operating mode by changing the settings of the following control parameters in the following order: (1) increasing the flow rate of the sub-chamber fuel gas in a ramp-like or step-like manner to the set value of the first operating mode, (2) advancing the fuel gas supply timing in a ramp-like or step-like manner to the set value of the first operating mode, (3) decreasing the air-fuel ratio in a ramp-like or step-like manner to the set value of the first operating mode, and (4) advancing the ignition timing in a ramp-like or step-like manner to the set value of the first operating mode.

[0041] (effect) As explained above, according to this embodiment, when transitioning between operating modes, the system first passes through a safe mode before transitioning to the destination operating mode. This suppresses the occurrence of abnormalities during transient states when transitioning between any operating modes. Furthermore, by consolidating the avoidance modes for when abnormalities occur into the safe mode, the complexity of the control logic during abnormalities is suppressed, and the number of set value patterns can be reduced. For example, by reducing the number of transition patterns between operating modes, set values ​​such as transition speed can be minimized. In addition, by ensuring stable operation during transient states through the safe mode, the set values ​​of the control parameters for each operating mode can be optimized (increased efficiency).

[0042] Figure 9 is a schematic block diagram showing the hardware configuration of a control device according to an embodiment. The computer 90 includes a processor 91, main memory 92, storage 93, and interface 94. The control device 10 described above is implemented in the computer 90. The operation of each processing unit described above is stored in the storage 93 in the form of a program. The processor 91 reads the program from the storage 93, loads it into the main memory 92, and executes the above processing according to the program. The processor 91 also allocates memory areas in the main memory 92 corresponding to each of the above-mentioned storage units according to the program. Examples of the processor 91 include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and a microprocessor.

[0043] The program may be for implementing some of the functions that the computer 90 is to perform. For example, the program may perform functions in combination with other programs already stored in storage, or in combination with other programs implemented in other devices. In other embodiments, the computer 90 may be equipped with a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions implemented by the processor 91 may be implemented by the integrated circuit. Such an integrated circuit is also included as an example of a processor.

[0044] Examples of storage 93 include HDDs (Hard Disk Drives), SSDs (Solid State Drives), magnetic disks, magneto-optical disks, CD-ROMs (Compact Disc Read Only Memory), DVD-ROMs (Digital Versatile Disc Read Only Memory), and semiconductor memory. Storage 93 may be an internal medium directly connected to the bus of the computer 90, or an external medium connected to the computer 90 via an interface 94 or a communication line. Furthermore, if this program is distributed to the computer 90 via a communication line, the computer 90 that receives the program may expand it into the main memory 92 and execute the above processing. In at least one embodiment, storage 93 is a tangible storage medium that is not temporary. The program may also be for implementing some of the functions described above. Moreover, the program may be a so-called differential file (differential program) that implements the functions described above in combination with other programs already stored in storage 93.

[0045] As described above, several embodiments relating to this disclosure have been explained, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0046] <Note> The control device, control method, and program described in each embodiment can be understood, for example, as follows:

[0047] (1) The control device according to the first embodiment includes a control unit that, when transitioning the engine's operating mode from a first operating mode to a second operating mode, transitions from the first operating mode to a safe mode, which is a common operating mode for which the control parameter settings are designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode. This makes it possible to suppress the occurrence of abnormalities during transient states when transitioning between any operating modes.

[0048] (2) The control device according to the second embodiment is the control device of (1), wherein the control unit retards the ignition timing of the spark plug by a predetermined amount, then increases the air-fuel ratio by a predetermined amount, then retards the fuel gas supply timing by a predetermined amount, and then decreases the fuel gas flow rate of the sub-chamber by a predetermined amount, thereby transitioning to the safe mode. This allows the system to switch from the first driving mode to safe mode.

[0049] (3) The control device according to the third embodiment is the control device according to (1) to (2), wherein the control unit increases the flow rate of the sub-chamber fuel gas, advances the fuel gas supply timing, decreases the air-fuel ratio, and advances the ignition timing to transition to the second operating mode. This allows the system to switch from safe mode to the second operating mode.

[0050] (4) The control device according to the fourth embodiment is the control device described in (1) to (3), wherein the control unit increases the flow rate of the sub-chamber fuel gas to the flow rate of the sub-chamber fuel gas in the second operating mode over a predetermined period of time, advances the fuel gas supply timing to the fuel gas supply timing in the second operating mode over a predetermined period of time, decreases the air-fuel ratio to the air-fuel ratio in the second operating mode over a predetermined period of time, and advances the ignition timing to the ignition timing in the second operating mode over a predetermined period of time, thereby transitioning to the second operating mode. This allows the system to switch from safe mode to the second operating mode.

[0051] (5) The control device according to the fifth embodiment is the control device described in (1) to (4), wherein the first operating mode is an operating mode using only natural gas as fuel, and the second operating mode is an operating mode using a mixed fuel of natural gas and hydrogen or hydrogen as fuel. This allows for a transition between an operating mode that uses hydrogen co-firing and an operating mode that uses only city gas.

[0052] (6) The control device according to the sixth embodiment is the control device described in (5), further comprising a determination unit that obtains the hydrogen mixing ratio in the fuel and determines that when the mixing ratio changes from 0%, the system transitions from the first operating mode to the second operating mode. This allows for the determination of whether to execute or start a mode transition between an operating mode that uses hydrogen co-firing and an operating mode that uses only city gas.

[0053] (7) The control device according to the seventh embodiment is the control device described in (5) to (6), wherein the control unit starts a transition from the safe mode to the second operating mode when the mixing ratio reaches the mixing ratio in the second operating mode, or when a predetermined time has elapsed since the mixing ratio in the second operating mode was reached. This allows for a stable transition to the second operating mode.

[0054] (8) The control device according to the eighth embodiment is the control device described in (1) to (7), wherein the safe mode comprises a first safe mode in which the set value of the control parameter is relatively close to that of the first operating mode, and a second safe mode in which the set value of the control parameter is relatively close to that of the second operating mode, and the control unit, when transitioning from the first operating mode to the second operating mode, transitions from the first operating mode to the first safe mode, from the first safe mode to the second safe mode, and from the second safe mode to the second operating mode. This allows for a more stable transition from the first operating mode to the second operating mode.

[0055] (9) In the control method according to the ninth aspect, when the engine control device transitions the engine's operating mode from a first operating mode to a second operating mode, it transitions from the first operating mode to a safe mode, which is a common operating mode for which the control parameter settings are designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.

[0056] (10) The program according to the tenth embodiment causes the computer to function as a means for transitioning the engine's operating mode from a first operating mode to a second operating mode, by transitioning from the first operating mode to a safe mode, which is a common operating mode in which the control parameter settings are designed to prevent abnormalities, and then transitioning from the safe mode to the second operating mode. [Explanation of symbols]

[0057] 1. Engine System 2. Hydrogen mixing device 3. Engine 4 cylinders 5. Piston 6. Combustion chamber 7. Spark plugs 8...Antechamber C1, C2, C3... sensors L1... Fuel supply line L2... Air supply line L3... Intake line L4... auxiliary fuel line L5... Exhaust line 10. Control device 11. Signal acquisition unit 12... Judgment section 13. Control Unit 90... Computer 91... Processor 92···Main Memory 93.. Storage 94. Interface 100... Gas engine

Claims

1. A control unit that, when transitioning the engine's operating mode from a first operating mode to a second operating mode, transitions from the first operating mode to a safe mode, which is a common operating mode designed to prevent malfunctions, and then transitions from the safe mode to the second operating mode. A control device equipped with the following features.

2. The control unit switches to the safe mode by retarding the ignition timing of the spark plug by a predetermined amount, then increasing the air-fuel ratio by a predetermined amount, then retarding the fuel gas supply timing by a predetermined amount, and then decreasing the fuel gas flow rate of the sub-chamber by a predetermined amount. The control device according to claim 1.

3. The control unit transitions to the second operating mode by increasing the flow rate of the sub-chamber fuel gas, advancing the fuel gas supply timing, decreasing the air-fuel ratio, and advancing the ignition timing. The control device according to claim 1 or claim 2.

4. The control unit increases the flow rate of the sub-chamber fuel gas to the flow rate of the sub-chamber fuel gas in the second operating mode over a predetermined period of time, advances the fuel gas supply timing to the fuel gas supply timing in the second operating mode over a predetermined period of time, decreases the air-fuel ratio to the air-fuel ratio in the second operating mode over a predetermined period of time, and advances the ignition timing to the ignition timing in the second operating mode over a predetermined period of time, thereby transitioning to the second operating mode. The control device according to claim 1 or claim 2.

5. The first operating mode is an operating mode using only natural gas as fuel, and the second operating mode is an operating mode using a mixed fuel of natural gas and hydrogen or hydrogen as fuel. The control device according to claim 1 or claim 2.

6. A determination unit that obtains the hydrogen mixing ratio in the fuel and determines that when the mixing ratio changes from 0%, the system transitions from the first operating mode to the second operating mode. The control device according to claim 5, further comprising:

7. The control unit initiates a transition from the safe mode to the second operating mode when the mixing ratio reaches the mixing ratio in the second operating mode, or when a predetermined time has elapsed since reaching the mixing ratio in the second operating mode. The control device according to claim 6.

8. The safe mode comprises a first safe mode in which the control parameter setting value is relatively close to that of the first operating mode, and a second safe mode in which the control parameter setting value is relatively close to that of the second operating mode. When the control unit transitions from the first operating mode to the second operating mode, it transitions from the first operating mode to the first safe mode, from the first safe mode to the second safe mode, and from the second safe mode to the second operating mode. The control device according to claim 1 or claim 2.

9. The engine control unit A control method for transitioning the engine's operating mode from a first operating mode to a second operating mode, wherein the engine transitions from the first operating mode to a safe mode, which is a common operating mode designed to prevent malfunctions, and then transitions from the safe mode to the second operating mode.

10. Computers, When transitioning the engine's operating mode from a first operating mode to a second operating mode, means for transitioning from the first operating mode to a safe mode, which is a common operating mode designed to prevent malfunctions, and from the safe mode to the second operating mode. A program designed to function as such.

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