Control device, engine system, control method, and program

Abstract

To provide control to switch between fuel mixing and non-fuel mixing during engine operation, while continuing a stable engine operation.SOLUTION: The control device is an engine control device and comprises: means for determining whether to perform co-combustion control using a mixed fuel, which is obtained by mixing a plurality of fuels, when the engine is in operation; means for controlling ignition timing of the engine; and means for performing air-fuel ratio control in a combustion chamber of the engine. When the determination means determines to perform the co-combustion control, the means for controlling ignition timing starts retard control of the ignition timing before supply of the mixed fuel is started, and completes the retard control before the supply of the mixed fuel is started. When the supply of the mixed fuel is started, the means for performing air-fuel ratio control performs the air-fuel ratio control with a target air-fuel ratio corresponding to a mixing ratio indicating the ratio of each of the plurality of fuels in the mixed fuel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device, an engine system, a control method, and a program. [Background technology]

[0002] As part of efforts to reduce CO2 emissions, a system has been proposed in which a gas engine is driven by a fuel made by blending hydrogen with fuel gases such as city gas (natural gas) to generate electricity. Conventional gas engines often use the same fuel throughout operation, and even when the fuel's gas properties are switched, the magnitude of the change is limited. In contrast, hydrogen has significantly different density and calories from city gas, so operating conditions using only city gas and those using a hydrogen-blended fuel produce unexpected changes. To address this, it is necessary to change the engine's ignition timing and air-fuel ratio depending on the hydrogen blend ratio. Furthermore, when switching between fuel blending and non-blended, it is necessary to change the air-fuel ratio parameters at an appropriate speed.

[0003] Patent Document 1 discloses a control method for changing the ignition timing of an air-fuel mixture so as to obtain the required torque when switching the air-fuel ratio in an engine that uses a mixture of fuels with different combustion speeds. However, changing the air-fuel ratio and ignition timing simultaneously can easily cause instability during the process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-209903 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need for technology that can switch between mixing and not mixing fuel while the engine is running, while maintaining stable engine operation.

[0006] The present disclosure provides a control device, an engine system, a control method, and a program that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The control device of the present disclosure is an engine control device that includes a means for determining whether or not to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels while the engine is operating, a means for controlling ignition timing of the engine, and a means for controlling the air-fuel ratio of a combustion chamber of the engine, and when the determining means determines that the multi-fuel control should be performed, the means for controlling ignition timing starts retarding control of the ignition timing before the mixed fuel is supplied and completes the retarding control before the mixed fuel is supplied, and when supply of the mixed fuel starts, the means for performing air-fuel ratio control performs the air-fuel ratio control with a target air-fuel ratio corresponding to a mixture ratio that indicates the proportion of each of the plurality of fuels in the mixed fuel.

[0008] The engine system of the present disclosure includes an engine, a fuel mixing device that mixes a plurality of fuels to generate a mixed fuel and supplies the mixed fuel to the engine, and the above-described control device.

[0009] The control method disclosed herein is a control method for an engine, and includes the steps of: determining whether or not to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels while the engine is operating; controlling ignition timing of the engine; and controlling an air-fuel ratio of a combustion chamber of the engine; and if it is determined in the determining step that the multi-fuel control will be performed, the ignition timing controlling step starts retarding control of the ignition timing before the mixed fuel is supplied and completes the retarding control before the mixed fuel is supplied; and the air-fuel ratio control step performs the air-fuel ratio control, when supply of the mixed fuel starts, to target an air-fuel ratio corresponding to a mixture ratio indicating the proportion of each of the plurality of fuels in the mixed fuel.

[0010] The program disclosed herein includes a step of causing a computer of an engine control device to determine whether or not to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels while the engine is running, a step of controlling ignition timing of the engine, and a step of performing air-fuel ratio control of a combustion chamber of the engine. If it is determined in the determining step that the multi-fuel control will be performed, the step of controlling ignition timing starts retarding control of the ignition timing before the mixed fuel is supplied and completes the retarding control before the mixed fuel is supplied, and the step of performing air-fuel ratio control causes a process to be executed to perform the air-fuel ratio control, when supply of the mixed fuel starts, with an air-fuel ratio corresponding to a mixture ratio indicating the proportion of each of the plurality of fuels in the mixed fuel. [Effects of the Invention]

[0011] According to the above-described control device, engine system, control method, and program, it is possible to switch between mixing and not mixing fuel while the engine is running, while the engine is running stably. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram illustrating an example of an engine system according to an embodiment. [Figure 2] 4 is a time chart showing an example of multi-fuel combustion control according to the embodiment. [Figure 3] FIG. 4 is a diagram illustrating an example of mode transition in multi-fuel combustion control according to the embodiment. [Figure 4] 10A and 10B are diagrams illustrating the operation when a stop condition for the multi-fuel combustion control according to the embodiment is met. [Figure 5] FIG. 2 is a schematic diagram illustrating an example of a hardware configuration of a controller according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Embodiment> The configuration and control of an engine system 1 of the present disclosure will be described below with reference to FIGS. FIG. 1 is a block diagram showing an example of an engine system according to an embodiment. The engine system 1 includes a hydrogen mixing device 2, an engine 3, a generator 4, a circuit breaker 5, a hydrogen mixing device controller 20 which is a control device for the hydrogen mixing device 2, an engine controller 30 which is a control device for the engine 3, and a generator controller 40 which is a control device for the generator 4, etc.

[0014] The hydrogen mixing device 2 mixes hydrogen with fuel gas such as city gas (natural gas) to produce a mixed fuel, and supplies the produced mixed fuel to the engine 3. The proportion of hydrogen in the mixed fuel is called the mixing ratio. The mixing ratio is controlled between 0 and several tens of percent. For example, when the engine 3 starts and enters a stable operating state, the mixing ratio gradually increases from 0% until it reaches a predetermined value, at which point the mixing ratio is maintained. If a sudden change in load or an abnormality in the engine 3 is detected, the mixing ratio is reduced to 0%. The hydrogen mixing device 2 includes a pipe 2A to which fuel gas (hereinafter referred to as city gas) is supplied, a pipe 2B to which hydrogen gas is supplied, and a pipe 2C to which the mixed fuel is supplied. The pipes 2A and 2B are connected to the pipe 2C at a mixing point 2D. A flow control valve 2a is provided in the pipe 2A, and a flow control valve 2b1 and a hydrogen shutoff valve 2b2 are provided in the pipe 2B. Pipes 2A and 2B are provided with pressure gauges (not shown), and hydrogen mixing device controller 20 controls the aperture of flow control valves 2a and 2b1 while hydrogen shutoff valve 2b2 is open based on the flow rates of hydrogen gas and city gas calculated from the measured pressure values ​​of pipes 2A and 2B, thereby controlling the mixing ratio at mixing point 2D to a desired value. The value of the mixing ratio may be set in hydrogen mixing device controller 20, or may be instructed by engine controller 30 or generator controller 40.

[0015] The engine 3 is a gas engine that uses city gas as fuel. It generates an air-fuel mixture by mixing the mixed fuel supplied from the hydrogen mixing device 2 with intake air (air) supplied through a pipe 3a, and then burns the generated air-fuel mixture to rotate and drive the output shaft 3b. The engine controller 30 operates the engine 3 mainly by performing combustion control and air-fuel ratio control. In the combustion control, feedback control is performed to maintain the engine 3's rotation speed and load constant. In the air-fuel ratio control, feedback control is performed to maintain a constant air-fuel ratio in the combustion chamber of the engine 3 by controlling a throttle valve (not shown) or the like provided in the piping system for the air-fuel mixture flowing into the combustion chamber, so that the air-fuel ratio reaches a target value. The configuration of the engine 3, combustion control, and air-fuel ratio control are well known, so detailed description will be omitted. The function of the engine controller 30 related to the mixed combustion control of this embodiment will be described later.

[0016] The generator 4 is connected to the engine 3 via the output shaft 3b, and generates electricity using the rotational driving force transmitted from the output shaft 3b. The generator 4 is connected to an electric power system (not shown) via a circuit breaker 5. The electric power generated by the generator 4 is supplied to a load 6 through the electric power system by opening and closing the circuit breaker 5. A generator controller 40 controls the generator 4, the circuit breaker 5, auxiliary equipment (not shown), etc.

[0017] The hydrogen mixing device controller 20, the engine controller 30, and the generator controller 40 are connected to one another via a network such as a LAN and signal lines. The control status of the engine system 1 is transmitted and received via the network, and fault information (fault contact signals) and the like are transmitted and received via signal lines, and this information is shared among the three controllers 20, 30, and 40. For example, the hydrogen mixing device controller 20 transmits to the engine controller 30 the hydrogen mixing ratio at the mixing point 2D and a mixing flag indicating that fuel is being mixed. The engine controller 30 transmits to the hydrogen mixing device controller 20 and the generator controller 40 the result of a determination as to whether or not multi-fuel control (operation of the engine 3 using a fuel mixture containing hydrogen) is possible (multi-fuel permission flag = ON, OFF) and a signal indicating the completion of ignition timing control (ignition timing advance completion signal, ignition timing retard completion signal). The hydrogen mixing device controller 20 or the generator controller 40 transmits to the engine controller 30 a signal instructing the start of multi-fuel control (multi-fuel control PB = ON). In addition, the generator controller 40 transmits a load signal indicating the magnitude of the load 6 to the engine controller 30 .

[0018] The engine controller 30 includes a signal acquisition unit 31 , a multi-fuel combustion possibility determination unit 32 , and a control unit 33 . The signal acquisition unit 31 acquires a load signal indicating the magnitude of the load 6 from the generator controller 40. The signal acquisition unit 31 makes decisions such as load shedding and load application based on the load signal. The signal acquisition unit 31 also acquires the mixing ratio at the mixing point 2D and a mixing flag from the hydrogen mixer controller 20. The signal acquisition unit 31 acquires an instruction signal to start multi-fuel combustion control (multi-fuel combustion control PB=ON) from the hydrogen mixer controller 20 or the generator controller 40.

[0019] The multi-fuel combustion feasibility determination unit 32 determines whether multi-fuel combustion control, i.e., whether the engine 3 is capable of operating on a mixed fuel obtained by mixing city gas with hydrogen, is possible. For example, the multi-fuel combustion feasibility determination unit 32 determines that multi-fuel combustion control is possible when the magnitude of the load 6 is equal to or greater than a predetermined reference value or when the engine 3 is considered to be in a stable operating state. Furthermore, for example, the multi-fuel combustion feasibility determination unit 32 determines that multi-fuel combustion control is impossible when the engine 3 is no longer in a stable operating state. Alternatively, the multi-fuel combustion feasibility determination unit 32 may determine that multi-fuel combustion control is impossible when an operator inputs an instruction to stop multi-fuel combustion control. If the multi-fuel combustion feasibility determination unit 32 determines that multi-fuel combustion control is possible, it transmits a multi-fuel combustion permission flag to the hydrogen mixing unit controller 20 and the generator controller 40, setting the multi-fuel combustion permission flag to ON. If the multi-fuel combustion control is determined to be impossible, it transmits the multi-fuel combustion permission flag to OFF. If it is determined that mixed combustion control is possible, for example, an operator or the like instructs the hydrogen mixing device controller 20 or the generator controller 40 to start mixed combustion control, and this instruction signal (mixed combustion control PB=ON) is sent to the engine controller 30.

[0020] The control unit 33 controls the engine 3. For example, when the signal acquisition unit 31 acquires an instruction signal to start multi-fuel combustion control (multi-fuel control PB=ON), the control unit 33 performs retard control (retard) to retard the ignition timing of the engine 3. When the retard control is completed, the control unit 33 notifies the hydrogen mixing device controller 20 of the completion of the retard control (ignition timing retard completion signal). When the hydrogen mixing device controller 20 receives the notification of the completion of the retard control, it starts mixing city gas and hydrogen gas and transmits the mixing ratio and a mixing flag to the engine controller 30. When the control unit 33 receives the mixing ratio and the mixing flag via the signal acquisition unit 31, it performs air-fuel ratio control according to the hydrogen mixing ratio. For example, the control unit 33 has a table that associates mixing ratios with air-fuel ratios, and calculates the air-fuel ratio according to the mixing ratio based on this table and the mixing ratio acquired from the hydrogen mixing device controller 20. Then, the control unit 33 performs feedback control using the calculated air-fuel ratio as a target so that the air-fuel ratio in the combustion chamber of the engine 3 becomes the target air-fuel ratio.

[0021] The control unit 33 also detects abnormalities in the engine 3, for example, based on values ​​detected by sensors provided at various locations on the engine 3. For example, criteria for determining whether a minor malfunction allows continuation of multi-fuel control, a minor malfunction that makes continuation of multi-fuel control impossible (a minor malfunction that affects air-fuel ratio control), or a major malfunction are determined in advance, and the control unit 33 determines whether a detected abnormality is a minor malfunction that allows continuation of multi-fuel control, a minor malfunction that makes continuation of multi-fuel control impossible, or a major malfunction based on these criteria, and displays the detected abnormality on a display unit or notifies the other controllers 20, 40 of details of the abnormality.

[0022] Furthermore, if the multi-fuel combustion feasibility determination unit 32 determines that multi-fuel combustion control is not possible during multi-fuel combustion control or if the operator instructs the hydrogen mixing device controller 20 to terminate the multi-fuel combustion control, the hydrogen mixing device controller 20 gradually or quickly (immediately) stops the fuel mixing. The control unit 33 then continues the air-fuel ratio control according to the mixture ratio while retarding the ignition timing. When the mixture ratio reaches 0%, the controller 33 returns the retarded ignition timing to its original state (advance control). In this manner, in this embodiment, when switching between fuel mixing and non-mixing during engine operation, the air-fuel ratio and the ignition timing are changed separately, rather than simultaneously. To start fuel mixing, the ignition timing is changed (retarded) while the air-fuel ratio is fixed, and then the air-fuel ratio is changed as the mixture ratio increases. To stop fuel mixing, the controller 33 changes the air-fuel ratio as the mixture ratio decreases while keeping the ignition timing fixed, and then returns the ignition timing to its original state when the mixture ratio reaches 0%. By controlling the air-fuel ratio and ignition timing separately in this way, the control can be simplified and made easier, and stable operation of the engine 3 can be continued when switching between mixing and not mixing fuel while the engine 3 is operating.

[0023] The switching of the multi-fuel combustion control while the engine is running will be described with reference to the time chart of FIG. At time t0, the engine 3 is started, and the output of the generator 4 begins to increase. At time t1, the output of the generator 4 reaches the rated load. The ignition timing of the engine 3 at this time is, for example, when the crank angle is 10° before top dead center. Thereafter, at time t2, a mixed combustion permission flag = ON is sent to the hydrogen mixing device controller 20, etc., and a command signal to start mixed combustion control (mixed combustion control PB = ON) is sent from the hydrogen mixing device controller 20 or the generator controller 40 to the engine controller 30. Upon receiving the command signal, the control unit 33 retards the ignition timing, for example, to a position 6° before top dead center. When the retard control is completed at time t3, the control unit 33 transmits an ignition timing retard completion signal to the hydrogen mixing device controller 20. The control unit 33 waits until a mixing in progress flag is sent from the hydrogen mixing device controller 20. During this time, the control unit 33 controls the air-fuel ratio based on the air-fuel ratio at a mixture ratio of 0%.

[0024] Shortly after receiving the ignition timing retard completion signal, at time t4, the hydrogen mixing device controller 20 opens the flow control valve 2b1 and the hydrogen shutoff valve 2b2 and gradually increases the hydrogen mixing ratio until a predetermined mixing ratio (e.g., 25%) is reached. When the flow control valve 2b1 and the hydrogen shutoff valve 2b2 are opened and mixing of hydrogen gas and city gas begins, the hydrogen mixing device controller 20 transmits a mixing flag and the current mixing ratio at the mixing point 2D to the engine controller 30. Upon receiving the mixing flag and mixing ratio, the control unit 33 calculates an air-fuel ratio according to the obtained mixing ratio and performs air-fuel ratio control with the calculated air-fuel ratio as a target. The control unit 33 continues air-fuel ratio control by changing the target air-fuel ratio in accordance with changes in the mixing ratio while keeping the ignition timing retarded.

[0025] When the predetermined mixture ratio is reached at time t5, the hydrogen mixing device controller 20 continues to supply the engine 3 with a mixed fuel made by mixing hydrogen and city gas at the predetermined mixture ratio until the mixed combustion feasibility determination unit 32 determines that mixed combustion control is not possible, or the operator inputs an instruction to stop mixed combustion control and sends the mixed combustion permission flag = OFF.

[0026] If the mixed-fuel-combustion permission flag is set to OFF by the mixed-fuel-combustion determination unit 32 at time t6 for some reason, the hydrogen mixing device controller 20 controls the flow control valves 2a and 2b1 to reduce the hydrogen mixture ratio to 0%. If the engine 3 deviates from an operating state in which mixed-fuel control is possible, or if the engine 3 experiences a minor malfunction that makes air-fuel ratio control insufficient, the hydrogen mixing device controller 20 reduces the mixture ratio to 0% over a certain period of time. Figure 2 shows a time chart for such a scenario. On the other hand, if a load dump or major malfunction occurs, the hydrogen mixing device controller 20 immediately closes the hydrogen shutoff valve 2b2 to quickly reduce the mixture ratio to 0%. While the mixture ratio is decreasing, the hydrogen mixing device controller 20 transmits a mixing flag and the mixture ratio to the engine controller 30. The control unit 33 retards the ignition timing and continues air-fuel ratio control by changing the target air-fuel ratio in response to the change in the mixture ratio.

[0027] When the mixture ratio reaches 0% at time t7, the hydrogen mixing device controller 20 stops sending the mixture flag. The control unit 33 performs air-fuel ratio control based on the air-fuel ratio when the mixture ratio is 0%. A predetermined time has elapsed since the mixture flag was no longer sent at time t7, and at time t8, the control unit 33 performs advance control on the ignition timing that had been retarded, returning it to the original ignition timing (10° before top dead center). When the advance control is completed at time t9, the control unit 33 sends an ignition timing advance completion signal to the hydrogen mixing device controller 20. Thereafter, at time t10, the output of the generator 4 is reduced in response to an instruction from an operator or the like.

[0028] FIG. 3 shows an overview of the transition of the control state in the multi-fuel combustion control of this embodiment. When the conditions for enabling multi-fuel combustion control are met from the multi-fuel control OFF state (S1), the multi-fuel combustion determination unit 32 permits multi-fuel combustion control (S2). The multi-fuel combustion determination unit 32 determines whether multi-fuel combustion control is possible based on whether stable operation of the engine 3 is possible after the start of multi-fuel combustion control. For example, if stable operation is possible even with an increased fuel mixture ratio, the unit increases the fuel mixture ratio to reduce CO2 emissions. However, if stable operation is difficult with the mixed fuel, the unit determines to stop the mixing. For example, the multi-fuel combustion determination unit 32 may determine that multi-fuel combustion control is possible (permit multi-fuel combustion control) when the magnitude of the load 6 acquired by the signal acquisition unit 31 exceeds a predetermined load. Alternatively, the unit 32 may determine that multi-fuel combustion control is possible (permit multi-fuel control) when the temperature of the lubricating oil or coolant is above a predetermined threshold, or when a certain period of time has passed since the start of the engine 3, and the operating condition is deemed stable. When the multi-fuel combustion permission determination unit 32 permits multi-fuel combustion control, it sends a multi-fuel combustion permission flag = ON to the hydrogen mixing device controller 20, etc. When the hydrogen mixing device controller 20, etc. receives the multi-fuel combustion permission flag = ON, it displays the information on the display unit. Based on the operator's instructions, the hydrogen mixing device controller 20, etc. sends an instruction signal to start multi-fuel combustion control (multi-fuel control PB = ON) to the engine controller 30.

[0029] Upon receiving the instruction signal to start multi-fuel combustion control, the control unit 33 determines to perform multi-fuel combustion control. If it determines to perform multi-fuel combustion control, the control unit 33 performs ignition timing retard control (S3). When the retard control is completed, the control unit 33 sends an ignition timing retard completion signal to the hydrogen mixing device controller 20. The hydrogen mixing device controller 20 increases the hydrogen mixing ratio and sends a multi-fuel combustion flag and the mixing ratio to the engine controller 30. The control unit 33 performs air-fuel ratio control based on the air-fuel ratio corresponding to the increased mixing ratio (S4). When the mixing ratio reaches a predetermined value, the hydrogen mixing device controller 20 maintains the hydrogen mixing ratio and sends a multi-fuel combustion flag and the mixing ratio to the engine controller 30. The control unit 33 continues air-fuel ratio control based on the air-fuel ratio corresponding to the mixing ratio (S4).

[0030] If a minor malfunction occurs in the ignition timing retard control (S3) or the multi-fuel combustion control (S4), the control unit 33 sends a multi-fuel control stop command (multi-fuel control automatic OFF selection flag = ON) to the hydrogen mixing device controller 20. Upon receiving the stop command, the hydrogen mixing device controller 20 reduces the hydrogen mixing ratio to 0% and sends the multi-fuel combustion in progress flag and the mixing ratio to the engine controller 30. The hydrogen mixing device controller 20 also sends a multi-fuel control stop command signal (multi-fuel control PB = OFF) to the engine controller 30. The control unit 33 performs air-fuel ratio control based on the air-fuel ratio in response to the increase in the mixing ratio (S5). When the mixing ratio reaches 0%, the control unit 33 performs ignition timing advance control (S6). When the advance control is completed, the control unit 33 sends an ignition timing advance completion signal to the hydrogen mixing device controller 20. The state of the multi-fuel combustion control returns to OFF (S1).

[0031] Next, the operation when the conditions for stopping the multi-fuel combustion control are met will be described with reference to Fig. 4. In Fig. 4, ECU, MFC, and PLC represent the engine controller 30, the hydrogen mixing device controller 20, and the generator controller 40, respectively. (1) When the conditions for co-firing control are not met If the conditions for multi-fuel combustion are not met during multi-fuel combustion control, the engine system 1 stops the multi-fuel combustion control using a normal sequence that gradually reduces the fuel mixture ratio, as illustrated in the time chart of FIG. 2. For example, if the coolant temperature or lubricant temperature falls outside the appropriate range or the load falls below a reference value, the multi-fuel combustion determination unit 32 determines to stop the multi-fuel combustion control. When the engine controller 30 detects that the conditions for multi-fuel combustion control are not met, the multi-fuel combustion determination unit 32 sends a multi-fuel combustion permission flag set to OFF to the hydrogen mixing device controller 20. When the generator controller 40 detects that the conditions for multi-fuel combustion control are not met, the generator controller 40 sends a multi-fuel combustion permission flag set to OFF to the hydrogen mixing device controller 20. When the multi-fuel combustion permission flag set to OFF is sent, the hydrogen mixing device controller 20 reduces the fuel mixture ratio using a normal sequence and stops fuel mixing. The hydrogen mixing device controller 20, engine controller 30, and generator controller 40 each display an indication that the conditions for multi-fuel combustion control are not met.

[0032] (2) When a minor malfunction occurs If a minor fault occurs during multi-fuel combustion control, the response will vary depending on the nature of the minor fault. In the case of a minor fault that makes it impossible to adequately control the air-fuel ratio, the engine system 1 stops multi-fuel combustion control using the normal sequence. When the engine controller 30 detects such a minor fault, the control unit 33 sends a stop command for multi-fuel control (multi-fuel control automatic OFF selection flag = ON) to the hydrogen mixing device controller 20. The control unit 33 also sends a minor fault contact signal to the generator controller 40. When the generator controller 40 detects a minor fault that affects air-fuel ratio control, the generator controller 40 sends a stop command for multi-fuel control (multi-fuel control automatic OFF selection flag = ON) to the hydrogen mixing device controller 20. When the multi-fuel control automatic OFF selection flag = ON is sent, the hydrogen mixing device controller 20 reduces the fuel mixture ratio using the normal sequence and stops fuel mixing. The hydrogen mixing device controller 20, engine controller 30, and generator controller 40 each display the fault type and other information on their own displays.

[0033] In the case of a minor fault that does not affect air-fuel ratio control, the engine system 1 continues multi-fuel combustion control. If a minor fault is detected in the hydrogen mixing device controller 20, the hydrogen mixing device controller 20 sends a minor fault contact signal to the generator controller 40 and sends details of the fault to the generator controller 40 via the network. If a minor fault is detected in the engine controller 30, the engine controller 30 sends a minor fault contact signal to the generator controller 40 and sends details of the fault to the generator controller 40 via the network. The hydrogen mixing device controller 20, engine controller 30, and generator controller 40 display the fault item and the like on their own display units.

[0034] (3) When a serious breakdown occurs If a serious failure occurs during mixed combustion control, the engine system 1 immediately stops mixed combustion control and shuts down the system. If the engine controller 30 or hydrogen mixing device controller 20 detects a serious failure, it sends a serious failure contact signal to the generator controller 40. When the generator controller 40 receives the serious failure contact signal or detects a serious failure, it sends a hydrogen shutoff valve close contact signal to the hydrogen mixing device controller 20. The hydrogen mixing device controller 20 immediately fully closes the hydrogen shutoff valve 2b2. In addition, the generator controller 40 stops operation of the generator 4. The hydrogen mixing device controller 20, engine controller 30, and generator controller 40 display the failure item on their own display units.

[0035] (effect) As described above, according to this embodiment, mixed combustion control is achieved by adding the hydrogen mixing device 2 and the controller 20 to a configuration of a general engine system that does not perform mixed combustion control. By adding the hydrogen mixing device 2 and other components and linking the controllers 20, 30, and 40, hydrogen mixed combustion can be achieved without making major changes to the hardware and software of conventional engine systems.

[0036] Furthermore, according to this embodiment, the engine controller 30 determines whether or not it is appropriate to start multi-fuel combustion control based on the operating state of the engine 3. If it is appropriate, it notifies the other controllers 20, 40 of this. Then, upon receiving a command signal from the other controllers 20, 40 to start multi-fuel combustion control, the engine controller 30 gradually retards the ignition timing. Once the ignition timing retard is complete, the engine controller 30 notifies the hydrogen mixing device controller 20 of this and waits until the mixing flag is set. After the ignition timing retard is complete, the hydrogen mixing device controller 20 starts mixing hydrogen and sends the mixing ratio and the mixing flag to the engine controller 30. The engine controller 30 controls the air-fuel ratio using the mixing ratio. Furthermore, upon receiving a command to end hydrogen mixing from the hydrogen mixing device controller 20, the generator controller 40, or the like, the engine controller 30 terminates the multi-fuel combustion control by reversing the above procedure. The three controllers 20, 30, and 40 work together to operate based on defined modes (modes S1 to S6 shown in FIG. 3), and by changing the control of ignition timing and air-fuel ratio control according to the mixture ratio in that order, it is possible to safely achieve multi-fuel combustion control without making major changes to conventional hardware and software.

[0037] Furthermore, according to this embodiment, if an abnormality occurs during multi-fuel combustion control and the conditions for multi-fuel combustion control are not met, the multi-fuel combustion control is stopped in the normal sequence, and an operator is notified by displaying a message on a panel or the like that the multi-fuel combustion control is inappropriate. If a minor malfunction occurs that does not require immediate shutdown and affects the multi-fuel combustion control (e.g., affects air-fuel ratio control), the multi-fuel combustion control is stopped in the normal sequence. However, if the minor malfunction does not affect the multi-fuel combustion control, the multi-fuel combustion control is continued. Furthermore, if a serious malfunction occurs, the hydrogen shutoff valve is immediately closed to stop the engine system 1. By classifying the situation as to whether the multi-fuel combustion control is inappropriate or if a malfunction occurs, the system can continue hydrogen multi-fuel combustion control as much as possible while ensuring safety when an abnormality occurs, contributing to CO2 reduction.

[0038] In the above embodiment, city gas and hydrogen gas are mixed, but the types of gases to be mixed are not limited to these. In addition, three or more types of gases may be mixed.

[0039] 5 is a schematic block diagram showing the hardware configuration of a controller according to an embodiment. The computer 90 includes a processor 91, a main memory 92, a storage 93, and an interface 94. The hydrogen mixing device controller 20, the engine controller 30, and the generator controller 40 described above are implemented in the computer 90. The operations of the above-described processing units are 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 in accordance with the program. The processor 91 also allocates storage areas in the main memory 92 corresponding to the above-described storage units in accordance with the program. Examples of the processor 91 include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and a microprocessor.

[0040] The program may be for realizing some of the functions to be performed by the computer 90. For example, the program may be combined with other programs already stored in storage or implemented in other devices to perform the functions. In other embodiments, the computer 90 may include 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 realized by the processor 91 may be realized by the integrated circuit. Such an integrated circuit is also an example of a processor.

[0041] Examples of storage 93 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and a semiconductor memory. Storage 93 may be an internal medium directly connected to the bus of computer 90, or an external medium connected to computer 90 via interface 94 or a communication line. Furthermore, when this program is distributed to computer 90 via a communication line, computer 90 that receives the program may load the program into main memory 92 and execute the above-described processing. In at least one embodiment, storage 93 is a non-transitory tangible storage medium.

[0042] The program may also be a program for realizing part of the above-described functions. Furthermore, the program may be a so-called differential file (differential program) that realizes the above-described functions in combination with another program already stored in storage 93.

[0043] As described above, several 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 implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0044] <Additional Notes> The control device, engine system, control method, and program described in each embodiment can be understood, for example, as follows.

[0045] (1) A control device according to a first aspect is an engine control device comprising: means for determining whether to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels while the engine is operating; means for controlling ignition timing of the engine; and means for controlling an air-fuel ratio of a combustion chamber of the engine; when the determining means determines that the multi-fuel control should be performed, the means for controlling ignition timing starts retarding control of the ignition timing before the mixed fuel is supplied and completes the retarding control before the mixed fuel is supplied; and when the supply of the mixed fuel starts, the means for performing air-fuel ratio control performs the air-fuel ratio control with a target air-fuel ratio corresponding to a mixture ratio indicating the proportion of each of the plurality of fuels in the mixed fuel. This allows the engine to be operated stably while switching from no fuel mixture to fuel mixture during engine operation. The determination means determines that the multi-combustion control should be performed when, for example, the multi-combustion feasibility determination unit 32 determines that multi-combustion control is possible, sends the multi-combustion permission flag = ON to the hydrogen mixing device controller 20, etc., and the control unit 33 receives an instruction signal to start multi-combustion control (multi-combustion control PB = ON). The determination means determines that the multi-combustion control should not be performed when, for example, the conditions for multi-combustion control are not met or the control unit 33 detects a minor or major malfunction that affects air-fuel ratio control.

[0046] (2) A control device according to a second aspect is the control device of (1), in which, when the multi-combustion control is stopped, the fuel mixing device that supplies the mixed fuel to the engine reduces the mixing ratio of the fuels other than one of the plurality of fuels in the mixed fuel, the means for performing the air-fuel ratio control continues the air-fuel ratio control that targets an air-fuel ratio according to the mixing ratio until the mixing ratio of all the fuels other than the one fuel becomes 0%, and after the mixing ratio becomes 0%, the means for controlling the ignition timing returns the ignition timing to the state it was in before the retard control. This allows the engine to be operated stably while switching from fuel mixing to fuel not mixing during engine operation. The determining means determines that the multi-fuel combustion control should be stopped when, for example, the engine controller 30 detects that the conditions for multi-fuel control have been removed and the multi-fuel combustion permission determining unit 32 sends a multi-fuel combustion permission flag of OFF to the hydrogen mixing device controller 20, or when the control unit 33 detects a minor or major malfunction that affects the air-fuel ratio control.

[0047] (3) A control device according to a third aspect is the control device of (1) to (2), wherein the determining means determines that the engine is in a stable operating state and determines to perform the multi-fuel combustion control when any of the engine load, lubricating oil temperature, and cooling water temperature falls within a predetermined range, and determines to stop the multi-fuel combustion control when any of the engine load, lubricating oil temperature, and cooling water temperature falls outside the range. If it is considered that the engine can be operated stably even with the multi-fuel combustion control, the multi-fuel combustion control is permitted, and if it is considered that stable operation of the engine cannot be maintained by performing the multi-fuel combustion control, it is determined to stop the multi-fuel combustion control, thereby making it possible to switch between fuel mixing and non-mixing while maintaining stable operation of the engine.

[0048] (4) An engine system according to a fourth aspect includes an engine, a fuel mixing device that mixes a plurality of fuels to generate a mixed fuel and supplies the mixed fuel to the engine, and the control device according to any one of (1) to (3). By adding a fuel mixing device and linking it with the engine and control device, it is possible to achieve mixed combustion control without making major changes to the hardware and software of conventional engine systems.

[0049] (5) An engine system according to a fifth aspect is the engine system of (4), wherein, when the determining means determines that the multi-combustion control is to be performed, the determining means notifies the fuel mixing device that the multi-combustion control is possible, and after receiving the notification, the fuel mixing device instructs the control device to start the multi-combustion control, and based on the instruction, the means for controlling the ignition timing starts the retard control. This allows the multi-fuel combustion control to be carried out only when the engine can be operated stably even if the multi-fuel combustion control is started.

[0050] (6) An engine system according to a sixth aspect is an engine system of (4) to (5), wherein the means for controlling ignition timing notifies the fuel mixing device of the completion of the retard control when the retard control is completed, and the fuel mixing device, after receiving the notification, starts generating the mixed fuel and supplying it to the engine and notifies the control device of the mixing ratio, and the means for performing the air-fuel ratio control calculates an air-fuel ratio according to the notified mixing ratio and performs the air-fuel ratio control with the calculated air-fuel ratio as a target. When starting dual-fuel combustion control, the ignition timing is changed first, followed by the mixture ratio (air-fuel ratio), allowing dual-fuel combustion control to be started safely without major changes to conventional hardware and software.

[0051] (7) An engine system according to a seventh aspect is an engine system according to any one of (4) to (6), wherein when the multi-fuel combustion control is stopped, the fuel mixing device reduces the mixture ratio to 0%, and the means for controlling the ignition timing returns the ignition timing to the state it was in before the retard control after the mixture ratio reaches 0%. When stopping multi-fuel combustion control, the mixture ratio (air-fuel ratio) is changed, followed by the ignition timing, which allows multi-fuel combustion control to be stopped safely without making major changes to conventional hardware and software.

[0052] (8) An engine system according to an eighth aspect is an engine system according to any one of (4) to (7), wherein the determining means classifies an abnormality occurring in the engine according to a predetermined criterion into a minor malfunction that allows the multi-combustion control to continue, a minor malfunction that makes the multi-combustion control impossible to continue, or a major malfunction that requires the operation of the engine to be stopped, and the fuel mixing device continues producing the mixed fuel when it determines that the minor malfunction allows the multi-combustion control to continue, reduces the mixing ratio over a predetermined time until the mixing ratio becomes 0%, when it determines that the minor malfunction makes the multi-combustion control impossible to continue, and immediately reduces the mixing ratio to 0% when it determines that the major malfunction is occurring. By changing the fuel mixture ratio depending on the nature of the malfunction that occurs during operation, it is possible to continue mixed combustion control as much as possible while ensuring safety in the event of an abnormality.

[0053] (9) A control method according to a ninth aspect is a control method for an engine, comprising the steps of: determining whether to perform multi-combustion control using a mixed fuel obtained by mixing a plurality of fuels while the engine is operating; controlling ignition timing of the engine; and controlling an air-fuel ratio of a combustion chamber of the engine; when it is determined in the determining step that the multi-combustion control is to be performed, the step of controlling ignition timing starts retarding control of the ignition timing before the mixed fuel is supplied and completes the retarding control before the mixed fuel is supplied; and when the supply of the mixed fuel is started, the step of controlling the air-fuel ratio performs the air-fuel ratio control with a target air-fuel ratio corresponding to a mixture ratio indicating the proportion of each of the plurality of fuels in the mixed fuel.

[0054] (10) A program according to a tenth aspect includes the steps of: causing a computer of an engine control device to determine whether or not to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels while the engine is running; controlling ignition timing of the engine; and controlling an air-fuel ratio of a combustion chamber of the engine. When it is determined in the determining step that the multi-fuel control is to be performed, the step of controlling ignition timing starts retarding control of the ignition timing before the mixed fuel is supplied and completes the retarding control before the mixed fuel is supplied. The step of controlling the air-fuel ratio causes the computer to execute a process of performing the air-fuel ratio control, when the supply of the mixed fuel starts, with the air-fuel ratio controlled to a target air-fuel ratio corresponding to a mixture ratio indicating the proportion of each of the plurality of fuels in the mixed fuel.

[0055] In the above-described embodiment, the mixed fuel is a mixture of city gas and hydrogen, and the combustion speed of a mixture of city gas and hydrogen is faster than that of city gas alone, so the ignition timing is retarded. On the other hand, some fuels mixed with city gas may have a slower combustion speed than that of city gas alone. In such cases, the control in the above-described embodiment can be modified to supply the mixed fuel first, and then advance the ignition timing. [Explanation of symbols]

[0056] 1. Engine System 2. Hydrogen mixing device 2a Flow control valve 2b1 Flow control valve 2b2 Hydrogen shut-off valve 3. Engine 4. Generator 5 Circuit breaker 6. Load 20. Hydrogen Mixing Device Controller 30···Engine controller 31 Signal acquisition unit 32...Co-firing possibility determination section 33 Control section 40···Generator Controller 90. Computer 91 Processor 92 Main Memory 93 Storage 94···Interface

Claims

1. An engine control device, a means for determining whether or not to perform multi-fuel combustion control using a mixed fuel obtained by mixing a plurality of fuels during operation of the engine; means for controlling the ignition timing of the engine; means for controlling the air-fuel ratio of a combustion chamber of the engine; Equipped with When the determining means determines that the mixed combustion control is to be performed, the means for controlling the ignition timing starts retarding control of the ignition timing before the supply of the mixed fuel is started and completes the retarding control before the supply of the mixed fuel is started; when the supply of the mixed fuel is started, the means for performing the air-fuel ratio control performs the air-fuel ratio control with a target air-fuel ratio corresponding to a mixture ratio indicating a proportion of each of the plurality of fuels in the mixed fuel. A control device comprising:

2. When the multi-combustion control is stopped, the fuel mixing device that supplies the mixed fuel to the engine reduces the mixing ratio of the fuel other than one of the plurality of fuels in the mixed fuel, the means for performing the air-fuel ratio control continues the air-fuel ratio control targeting an air-fuel ratio according to the mixture ratio until the mixture ratios of all the fuels other than the one fuel become 0%, After the mixture ratio reaches 0%, the means for controlling the ignition timing returns the ignition timing to the state before the retard control. The control device according to claim 1 .

3. The determining means determines that the engine is in a stable operating state and determines to perform the multi-fuel combustion control when any of the engine load, lubricating oil temperature, and cooling water temperature falls within a predetermined range, and determines to stop the multi-fuel combustion control when any of the engine load, lubricating oil temperature, and cooling water temperature falls outside the range. The control device according to claim 1 or 2.

4. The engine and a fuel mixing device that mixes a plurality of fuels to generate a mixed fuel and supplies the mixed fuel to the engine; The control device according to claim 1 or 2; An engine system comprising:

5. When the determining means determines that the multi-fuel combustion control is to be performed, the determining means notifies the fuel mixing device that the multi-fuel combustion control is possible, After receiving the notification, the fuel mixing device instructs the control device to start the multi-combustion control, The means for controlling the ignition timing starts the retard control based on the instruction. The engine system of claim 4.

6. the means for controlling the ignition timing notifies the fuel mixing device of the completion of the retard control when the retard control is completed; After receiving the notification, the fuel mixing device starts generating the mixed fuel and supplying it to the engine, and notifies the control device of the mixing ratio; the means for performing the air-fuel ratio control calculates an air-fuel ratio according to the notified mixture ratio, and performs the air-fuel ratio control with the calculated air-fuel ratio as a target. The engine system of claim 4.

7. When the mixed combustion control is stopped, The fuel mixing device reduces the mixing ratio to 0%, the means for controlling the ignition timing returns the ignition timing to the state before the retard control after the mixture ratio becomes 0%. The engine system of claim 4.

8. the determining means classifies the abnormality occurring in the engine into one of a minor malfunction that allows the multi-fuel combustion control to continue, a minor malfunction that makes it impossible to continue the multi-fuel combustion control, and a major malfunction that requires the operation of the engine to be stopped, based on predetermined criteria; When the fuel mixing device determines that a minor malfunction has occurred that allows the continuation of the mixed combustion control, it continues to produce the mixed fuel; when the fuel mixing device determines that a minor malfunction has occurred that prevents the continuation of the mixed combustion control, it reduces the mixing ratio until the mixing ratio reaches 0% over a predetermined time; and when the fuel mixing device determines that a major malfunction has occurred, it immediately reduces the mixing ratio to 0%. The engine system of claim 4.

9. A method for controlling an engine, comprising: a step of determining whether or not to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels during operation of the engine; controlling ignition timing of the engine; controlling the air-fuel ratio of a combustion chamber of the engine; and When it is determined in the determining step that the multi-fuel combustion control is to be performed, In the step of controlling the ignition timing, a retard control of the ignition timing is started before the supply of the mixed fuel is started, and the retard control is completed before the supply of the mixed fuel is started, and when the supply of the mixed fuel is started, the step of performing the air-fuel ratio control performs the air-fuel ratio control with a target air-fuel ratio corresponding to a mixture ratio indicating a proportion of each of the plurality of fuels in the mixed fuel. Control method.

10. The engine control computer a step of determining whether or not to perform multi-fuel control using a mixed fuel obtained by mixing a plurality of fuels during operation of the engine; controlling ignition timing of the engine; controlling the air-fuel ratio of a combustion chamber of the engine; and When it is determined in the determining step that the multi-fuel combustion control is to be performed, In the step of controlling the ignition timing, a retard control of the ignition timing is started before the supply of the mixed fuel is started, and the retard control is completed before the supply of the mixed fuel is started, In the step of controlling the air-fuel ratio, when the supply of the mixed fuel is started, the air-fuel ratio control is performed with a target air-fuel ratio corresponding to a mixture ratio indicating a proportion of each of the plurality of fuels in the mixed fuel; A program that executes the following.

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