Control device, control method, and program
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025039147_13082026_PF_FP_ABST
Abstract
Description
Control Device, Control Method, and Program
[0001] This disclosure relates to a control device, a control method, and a program. This disclosure claims priority based on Japanese Patent Application No. 2025-017662 filed in Japan on February 5, 2025, the content of which is incorporated herein by reference.
[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 changes in fuel properties and 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 ignition properties and a high combustion speed.
[0003] However, since the fuel properties at the engine inlet change moment by moment depending on the operating load, plant layout, etc., it is difficult to uniquely determine the appropriate values for the fuel properties at each moment. As a countermeasure, a method of monitoring the fuel properties at the engine inlet can be mentioned, but this leads to increased costs due to the increase in equipment.
[0004] In case the adjustment of set values such as ignition timing and air-fuel ratio does not go well, if an avoidance mode for abnormalities is provided for each type of abnormality, the number of operating modes increases, the control becomes complicated, and in addition, the increase in set values is likely 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 cooling, then adjusting the intake air amount, and finally ending the switching between the first combustion mode with a fuel-lean state and the second combustion mode at the theoretical air-fuel ratio when transitioning the operating mode between them. However, Patent Document 1 does not disclose control for suppressing the occurrence of abnormalities in the transient state when transitioning between any operating modes.
[0006] Japanese Unexamined Patent Application Publication No. 202-34303
[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.
[0009] According to one aspect of the present disclosure, 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 in which the set values of the control parameters are designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.
[0010] According to one aspect of the present disclosure, when an 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 in which the control parameter settings are designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.
[0011] According to one aspect of the present disclosure, the program 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.
[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.
[0013] This is a schematic diagram of a gas engine system according to the embodiment. This is a diagram illustrating a conventional operating mode transition. This is a diagram illustrating an operating mode transition according to the embodiment. This is a diagram illustrating an example of conventional operating mode transition control. This is a diagram illustrating an example of operating mode transition control according to the embodiment. This is a diagram illustrating an example of operating mode transition according to the embodiment. This is a first flowchart showing an example of operating mode transition control according to the embodiment. This is a second flowchart showing an example of operating mode transition control according to the embodiment. This is a diagram showing an example of the hardware configuration of the control device according to the embodiment.
[0014] <Embodiment> (Configuration) The control method during operation mode transitions of the present 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 unit 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 unit 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 unit 2 can also supply natural gas alone or hydrogen alone as fuel gas to the engine 3.
[0016] Engine 3 is a gas engine that uses a fuel mixture of natural gas and hydrogen, natural gas without hydrogen, or pure hydrogen as fuel gas. It generates a fuel mixture by mixing the fuel gas supplied from the hydrogen mixing device 2 through the fuel supply line L1 with air supplied through the air supply line L2, and outputs power by burning the generated mixture. Engine 3 comprises a fuel supply line L1, an air supply line L2, an intake line L3 connected to lines L1 and L2 to generate the fuel mixture, an auxiliary 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, and a sub-chamber (sub-combustion chamber) 8, etc. The fuel mixture is supplied to the cylinder 4 through the intake line L3, and fuel gas is supplied to the sub-chamber 8 through the auxiliary fuel line L4. The flame formed by igniting the spark plug 7 in the sub-chamber 8 is blown into the combustion chamber 6, where the fuel mixture is burned. The exhaust gas after combustion is discharged through the exhaust line L5. The exhaust line L5 is equipped with a sensor C2 for measuring the temperature of the exhaust gas and a sensor C3 for detecting the components of the exhaust gas. The cylinder 4 is equipped with a sensor C1 for measuring the pressure inside the cylinder 4. The information measured by 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 comprises a signal acquisition unit 11, a determination unit 12, and a control unit 13. The signal acquisition unit 11 acquires information measured by each sensor from sensors C1 to C3. The signal acquisition unit 11 acquires fuel switching commands, the set value of the mixing ratio in the hydrogen mixing device 2, or the measured value of the mixing ratio, etc.
[0018] The determination unit 12 determines whether or not to transition the operating mode. For example, if a change in the mixture ratio (change in combustion characteristics) occurs, the determination unit 12 determines to transition the operating mode to an operating mode corresponding to the hydrogen mixture ratio. In this embodiment, when transitioning from the first operating mode to the second operating mode, the transition to the second operating mode is performed via a common operating mode (referred to as the safe mode) in which the control parameter settings are designed so that no abnormalities occur regardless of the operating mode transitioned from. The determination unit 12 determines the timing of the transition from this safe mode to the second operating mode. For example, it may be determined to transition to the second operating mode when the fuel switching is complete, or it may be determined to transition to the second operating mode after the state has stabilized after the fuel switching is complete. Regardless of the transition of the operating mode, the determination unit 12 determines whether or not abnormal combustion or other issues have occurred during operation, and if an abnormality occurs, it determines to transition from the currently running operating mode to the safe mode. Then, after transitioning to the safe mode, it determines whether or not the abnormality has been resolved, and if the abnormality has been resolved, it determines to return to the original operating mode.
[0019] Regarding this abnormality detection, the determination unit 12 determines the combustion state of the engine 3. For example, if the pressure measured by 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 if they fall within the normal range, it determines that combustion is stable. Similarly, if the exhaust gas temperature or the temperature change per unit time measured by sensor C2 deviates from the normal range, the determination unit 12 determines that abnormal combustion has occurred, and if they fall within the normal range, it determines that combustion is stable. If the exhaust gas components, component ratios, or component changes measured by sensor C3 deviate from the normal range, the determination unit 12 determines that abnormal combustion has occurred, and if they fall within the normal range, it determines that combustion is stable.
[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 a valve V3 etc. provided in the sub-fuel line L4, and controls 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 by advancing or delaying them. 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] 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. When operation in low NOx mode is instructed, the control unit 13 changes the operating mode from any other 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] When the hydrogen concentration is changed during the operation mode switch, the control unit 13 also switches the crankcase purge of the engine 3 ON / OFF. This is because if the fuel gas contains hydrogen, there is a possibility that unburned gas will 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 switch is completed, or for a while after the switch is completed), 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 switch).
[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 are performed 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. 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 is controlled to strengthen combustion. In this case, in order to suppress abnormal combustion caused by sudden changes in the 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. 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 then 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 when transitioning between operating modes with a specific example. We will explain using the example of transitioning 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, we will explain the conventional control with reference to Figure 4. Figure 41 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 shows the change in the 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. 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 output of the fuel switching command. Conventional control systems gradually retard the ignition timing in accordance with this decrease in hydrogen concentration. In this case, for example, moment-by-moment setting values, as shown by the solid line in Figure 42, are prepared in advance, and the ignition timing is controlled according to these setting 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. 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 allows for abnormality avoidance). 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] 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 advance of the ignition timing from 6 seconds onwards in Figure 52 is an example of a staged transition.
[0029] 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 in either case, which may lead to combustion instability or decreased efficiency. For example, comparing the control parameters of operating mode 1 and 2, operating mode 2 has a retarded ignition timing and a larger air-fuel ratio compared to operating mode 1. If we consider 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 combustion instability and decreased efficiency. If we consider a scenario where 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 by 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 this situation, 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), excessive efficiency degradation and driving stabilization due to avoidance actions to switch to safe mode can be suppressed.
[0030] Figure 6 shows an example of the operating mode transition 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] 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, the control flow during the transition of operating modes will be explained with reference to Figures 7 and 8. Figure 7 shows an example of control when transitioning the operating mode from the first operating mode to the second operating mode. Assume that the 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 that instructs 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. 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 reaches 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 reached 50%, or it may determine that the transition conditions have been met when the mixing ratio reaches 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 the following 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] 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] In the explanation of Figure 7, the first operating mode was designated as operating mode 1 and the second operating mode as operating mode 2. However, even if the first operating mode is designated as operating mode 1 and the second operating mode as 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, the control flow when an abnormality occurs during operation in a certain operating mode will be explained. The determination unit 12 detects the occurrence of 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] When 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 setting values 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 setting value of the first operating mode, (2) advancing the fuel gas supply timing in a ramp-like or step-like manner to the setting value of the first operating mode, (3) decreasing the air-fuel ratio in a ramp-like or step-like manner to the setting value of the first operating mode, and (4) advancing the ignition timing in a ramp-like or step-like manner to the setting value of the first operating mode.
[0041] (Effects) As described above, according to this embodiment, when transitioning between operating modes, the system first goes through safe mode before transitioning to the destination operating mode. This suppresses the occurrence of abnormalities during transient states when transitioning between any operating modes. By consolidating the avoidance modes for when abnormalities occur into 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. By ensuring stable operation during transient states with 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 of the above-described processing units 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-described processing according to the program. The processor 91 allocates storage areas in the main memory 92 corresponding to each of the above-described storage units according to the program. Examples of the processor 91 include a CPU (Central Processing Unit), a GPU (Graphics 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 include, in addition to or instead of the above configuration, a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device). 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 the storage 93 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), semiconductor memory, and the like. The storage 93 may be an internal medium directly connected to the bus of the computer 90, or may be an external medium connected to the computer 90 via the interface 94 or a communication line. When this program is distributed to the computer 90 via a communication line, the computer 90 that has received the distribution may expand the program in the main memory 92 and execute the above-described processing. In at least one embodiment, the storage 93 is a non-transitory tangible storage medium. The program may be for realizing a part of the functions described above. Further, the program may be a so-called difference file (difference program) that realizes the above-described functions in combination with other programs already stored in the storage 93.
[0045] As described above, some embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be executed in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and its equivalent scope.
[0046] <Supplementary Note> The control device, control method, and program described in each embodiment are understood as follows, for example.
[0047] (1) When the control device according to the first aspect shifts the engine operation mode from the first operation mode to the second operation mode, it shifts from the first operation mode to a safe mode, which is a common operation mode in which the set value of the control parameter is designed to avoid abnormalities, and includes a control unit that shifts from the safe mode to the second operation mode. As a result, it is possible to suppress the occurrence of abnormalities in the transient state regardless of the transition between any operation modes.
[0048] (2) The control device according to the second aspect is the control device of (1), and the control unit shifts to the safe mode by retarding the ignition timing of the ignition 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 sub-chamber fuel gas flow rate by a predetermined amount. As a result, it is possible to shift from the first operation mode to the safe mode.
[0049] (3) The control device according to the third aspect is the control device of (1) to (2), and the control unit shifts to the second operation 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. As a result, it is possible to shift from the safe mode to the second operation mode.
[0050] (4) The control device according to the fourth aspect is the control device described in (1) to (3), and the control unit shifts to the second operation mode by increasing the flow rate of the sub-chamber fuel gas to the flow rate of the sub-chamber fuel gas in the second operation mode over a predetermined time, advancing the fuel gas supply timing to the fuel gas supply timing in the second operation mode over a predetermined time, decreasing the air-fuel ratio to the air-fuel ratio in the second operation mode over a predetermined time, and advancing the ignition timing to the ignition timing in the second operation mode over a predetermined time. As a result, it is possible to shift from the safe mode to the second operation 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 makes it possible to transition between an operating mode with hydrogen co-firing and an operating mode using 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 acquires 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 makes it possible to perform execution and start determination of mode transitions between the hydrogen co-firing operating mode and the city gas-only operating mode.
[0053] (7) The control device according to the seventh embodiment is the control device described in (5) to (6), wherein the control unit starts transitioning 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 enables 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 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. This makes it possible to transition from the first operating mode to the second operating mode more stably.
[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 in 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.
[0057] 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.
[0058] 1...Engine system 2...Hydrogen mixing device 3...Engine 4...Cylinder 5...Piston 6...Combustion chamber 7...Spark plug 8...Sub-chamber C1, C2, C3...Sensors L1...Fuel supply line L2...Air supply line L3...Intake line L4...Sub-fuel line L5...Exhaust line 10...Control device 11...Signal acquisition unit 12...Determination unit 13...Control unit 90...Computer 91...Processor 92...Main memory 93...Storage 94...Interface 100...Gas engine
Claims
1. A control device comprising 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.
2. The control device according to claim 1, wherein the control unit delays the ignition timing of the spark plug by a predetermined amount, then increases the air-fuel ratio by a predetermined amount, then delays 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 to transition to the safe mode.
3. The control device according to claim 1 or 2, wherein 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.
4. The control device according to claim 1 or 2, 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 to transition to the second operating mode.
5. The control device according to claim 1 or claim 2, 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.
6. The control device according to claim 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 device transitions from the first operating mode to the second operating mode.
7. The control device according to claim 6, wherein 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 the mixing ratio in the second operating mode was reached.
8. The control device according to claim 1 or 2, 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, transitions from the first safe mode to the second safe mode, and transitions from the second safe mode to the second operating mode.
9. A control method in which, when an 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 designed to prevent abnormalities, and then transitions from the safe mode to the second operating mode.
10. A program for causing a 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.