Diesel engine control device, diesel engine, and diesel engine control method

Abstract

To provide a diesel engine control device, a diesel engine, and a diesel engine control method capable of restraining fluctuation in torque which can occur at switching of an operation state of a supercharger.SOLUTION: A control device for a diesel engine having a turbocharger and a supercharger as a super charger includes: a clutch control section for switching between an engaged state and a disengaged state of a clutch interposed between a driving shaft and the supercharger of the engine; a fuel injection period control section for controlling a fuel injection period on the basis of first association information in which engine speed, an accelerator opening, and a fuel injection period to the engine are preliminarily associated; and a fuel injection start timing control section for controlling fuel injection start timing to the engine. The fuel injection start timing control section controls the fuel injection start timing on the basis of the association information which is different for each of operation states of the supercharger.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a diesel engine control device, a diesel engine, and a method for controlling a diesel engine. [Background technology]

[0002] Some diesel engines are equipped with turbochargers and superchargers as superchargers. When the engine is started or running at low speed and low load, the exhaust gas energy required to drive the turbine may be insufficient, making it difficult to ensure sufficient supercharging pressure. For this reason, superchargers are used as supercharging means to assist the turbocharger when the engine is started or running at low speed and low load (see Patent Document 1). Some superchargers perform supercharging by mechanically driving a compressor from the engine crankshaft via power transmission means such as a gear or belt.

[0003] Diesel engines have two operating modes: a first operating mode in which both a turbocharger and a supercharger are used for supercharging, and a second operating mode in which only a turbocharger is used for supercharging. Some diesel engines are equipped with a flow path switching device, such as a valve, that switches the intake flow path in order to change the operating mode (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-80406 Summary of the Invention [Problem to be solved by the invention]

[0005] When the operating mode of a diesel engine is switched, the operating state (drive state or stop state) of the supercharger changes. This changes the scavenging pressure and mechanical loss of the engine, which can cause a sudden change in the fuel economy and torque of the engine. If a diesel engine control device were to calculate the fuel injection period (fuel injection amount) from the accelerator opening and engine speed input by the driver, and then calculate the fuel injection period (fuel injection amount) from the engine speed and fuel injection period (fuel injection amount), the influence of the sudden change in the scavenging pressure and mechanical loss of the engine when the operating mode is switched would not be taken into consideration. Therefore, when the operating mode is switched, a change in engine torque that is not intended by the driver of the vehicle equipped with the diesel engine may occur, requiring the driver to make additional accelerator adjustments.

[0006] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a diesel engine control device, a diesel engine, and a control method for a diesel engine that can suppress torque fluctuations that may occur when switching the operating state of a supercharger. [Means for solving the problem]

[0007] A control device for a diesel engine according to an embodiment of the present disclosure includes: A control device for a diesel engine equipped with a turbocharger and a supercharger as a supercharger, The above diesel a clutch control unit that switches between an engaged and disengaged state of a clutch interposed between a drive shaft of the engine and the supercharger; The above diesel Engine speed, throttle opening and diesel a fuel injection period control unit that controls the fuel injection period based on first association information that associates the fuel injection period with the engine in advance; The above diesel a fuel injection start timing control unit that controls the start timing of fuel injection into the engine, The control device When the supercharger is in a driving state, diesel second association information in which the engine speed, the fuel injection period, and the fuel injection start timing are associated in advance; When the supercharger is stopped, diesel third association information that associates in advance an engine speed, the fuel injection period, and the fuel injection start timing, the third association information being different from the second association information; The fuel injection start timing control unit When the supercharger is in a driving state, the fuel injection start timing is controlled based on the second association information, and when the supercharger is in a stopped state, the fuel injection start timing is controlled based on the third association information.

[0008] A diesel engine according to an embodiment of the present disclosure includes the control device.

[0009] A control method for a diesel engine according to one embodiment of the present disclosure includes: A control method for a diesel engine equipped with a turbocharger and a supercharger as a supercharger, comprising: The aforementioned diesel a clutch switching step of switching between an engaged and disengaged state of a clutch interposed between a drive shaft of the engine and the supercharger; The aforementioned diesel Engine speed, throttle opening and diesel a fuel injection period control step of controlling the fuel injection period based on first association information that associates the fuel injection period into the engine in advance; The aforementioned diesel a fuel injection start timing control step of controlling a fuel injection start timing into the engine, The fuel injection start timing control step includes: When the supercharger is in a driving state, diesela first fuel injection start timing control step of controlling the fuel injection start timing when the supercharger is in the driving state based on second association information that associates in advance an engine speed, the fuel injection period, and the fuel injection start timing; When the supercharger is stopped, diesel and a second fuel injection start timing control step of controlling the fuel injection start timing when the supercharger is in the stopped state based on third association information that associates in advance the engine speed, the fuel injection period, and the fuel injection start timing, the third association information being different from the second association information. [Effects of the Invention]

[0010] At least one embodiment of the present disclosure provides a diesel engine control device, a diesel engine, and a control method for a diesel engine that can suppress torque fluctuations that may occur when switching the operating state of a supercharger. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram illustrating a configuration of a diesel engine equipped with a control device according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is an explanatory diagram for explaining control of a clutch control unit in one embodiment. [Figure 5] 3 is an explanatory diagram for explaining control of a fuel injection period control unit in one embodiment. FIG. [Figure 6] 10 is an explanatory diagram for explaining a change in state when the state of a clutch of a diesel engine in a comparative example is switched. FIG. [Figure 7]5 is an explanatory diagram for explaining the control of a fuel injection start timing control unit of a comparative example. FIG. [Figure 8] 3 is an explanatory diagram for explaining control of a fuel injection start timing control unit in one embodiment. FIG. [Figure 9] FIG. 1 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. [Figure 10] FIG. 2 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. [Figure 11] FIG. 4 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. [Figure 12] FIG. 2 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. [Figure 13] FIG. 4 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. [Figure 14] FIG. 1 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. [Figure 15] FIG. 2 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. [Figure 16] FIG. 4 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. [Figure 17] FIG. 2 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. [Figure 18] FIG. 4 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," or "have" one element are not exclusive expressions that exclude the presence of other elements. Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

[0013] (Diesel engine) Fig. 1 is a schematic diagram illustrating the configuration of a diesel engine equipped with a control device according to one embodiment of the present disclosure. As shown in Fig. 1, a control device 2 for a diesel engine 1 according to some embodiments of the present disclosure is mounted on the diesel engine 1 that is equipped with a turbocharger 3 and a supercharger 4 as superchargers. In other words, the diesel engine 1 is equipped with the control device 2, the turbocharger 3, and the supercharger 4. In the following embodiments, a two-stroke diesel engine will be described as an example of the diesel engine 1, but the present disclosure is applicable to diesel engines 1 other than two-stroke engines.

[0014] The diesel engine 1 further includes an engine body 5 configured to generate power by burning fuel therein, an intake line 11 for compressing and supplying intake air (gas, for example, air) to the engine body 5, an exhaust line 12 for guiding exhaust gas discharged from the engine body 5, a fuel injection device (fuel injection valve) 13 configured to inject liquid fuel into the engine body 5, and a fuel supply line 14 for supplying liquid fuel to the fuel injection device 13. Hereinafter, the engine body 5 may be simply referred to as the engine 5.

[0015] The engine 5 includes at least one cylinder 51, at least one piston 52 housed inside the at least one cylinder 51 so that each piston can reciprocate axially, and a drive shaft 53 that converts the reciprocating motion of the at least one piston 52 into rotational force. The engine 5 has a combustion chamber 15 defined by the cylinder 51 and the piston 52. The engine 5 compresses and heats gas supplied to the combustion chamber 15 through the intake line 11 by the piston 52 to a temperature above the ignition point of the liquid fuel. Liquid fuel is injected from the fuel injector 13 into this compressed and heated gas, causing the liquid fuel to self-ignite. The piston 52 is pushed out by the expansion of combustion gas generated by the self-ignition. The reciprocating motion of the piston 52 is then converted into rotational force (power) by the drive shaft 53 via a connecting rod (not shown) or the like.

[0016] The fuel injection device 13 is electrically connected to the control device 2 via wire or wireless communication. The fuel injection device 13 is configured so that the fuel injection start timing TS (injection crank angle) and fuel injection period TQ to the engine 5 are controlled by the control device 2. In the illustrated embodiment, the fuel injection device 13 is connected to a common rail (not shown) in which high-pressure liquid fuel is stored, and is configured to inject high-pressure liquid fuel (unburned fuel) into the combustion chamber 15. Note that the fuel injection device 13 may also be configured to inject high-pressure liquid fuel (unburned fuel) into the intake line 11 near the combustion chamber 15.

[0017] (Turbocharger) The turbocharger 3 is driven by the energy of exhaust gas discharged from the engine 5 and is configured to compress gas (e.g., air) introduced into the engine 5. The turbocharger 3 includes a rotating shaft 31, a compressor 32, and a turbine 33. The compressor 32 includes an impeller 34 provided in the intake line 11 described above and a compressor housing 35 that rotatably houses the impeller 34. The impeller 34 is mechanically connected to one side of the rotating shaft 31. The turbine 33 includes a turbine rotor 36 provided in the exhaust line 12 described above and a turbine housing 37 that rotatably houses the turbine rotor 36. The turbine rotor 36 is mechanically connected to the other side of the rotating shaft 31.

[0018] The gas that has passed through the impeller 34 of the compressor 32 is guided through the intake line 11 to the combustion chamber 15 of the engine 5, and is used for combustion in the combustion chamber 15. The exhaust gas generated by the combustion in the combustion chamber 15 is guided through the exhaust line 12 to the turbine rotor 36 of the turbine 33. The turbocharger 3 is configured to rotate the turbine rotor 36 using the energy of the exhaust gas discharged from the engine 5. The impeller 34 is mechanically connected to the turbine rotor 36 via the rotating shaft 31, and therefore rotates in conjunction with the rotation of the turbine rotor 36. The turbocharger 3 is configured to compress the gas passing through the impeller 34 by the rotation of the impeller 34, increase the density of the gas, and send it to the engine 5.

[0019] (Supercharger) The diesel engine 1 includes a clutch 16 interposed between a drive shaft 53 of the engine 5 and a supercharger 4. The supercharger 4 is configured to be driven by power extracted from the drive shaft 53 of the engine 5 and compress gas introduced into the engine 5. The supercharger 4 includes an impeller 41 provided downstream of the impeller 34 of the compressor 32 in the intake line 11, a housing 42 that rotatably accommodates the impeller 41, and a rotating shaft 43 having the impeller 41 attached to one side. The other side of the rotating shaft 43 is mechanically coupled to the drive shaft 53 of the engine 5 via a power transmission device that includes the clutch 16. As shown in FIG. 1 , the diesel engine 1 may also include a gear mechanism 17 interposed between the drive shaft 53 and the clutch 16 and capable of setting a predetermined gear ratio.

[0020] The intake line 11 described above includes a first intake flow path 11A connecting the compressor 32 and the engine 5, the first intake flow path 11A having the impeller 41 of the supercharger 4 provided therein, and a second intake flow path (bypass flow path) 11B connecting the compressor 32 and the engine 5 while bypassing the supercharger 4. In the illustrated embodiment, the second intake flow path 11B branches off from the first intake flow path 11A at a branching point 111 located upstream of the impeller 41 of the supercharger 4, and merges with the first intake flow path 11A at a merging point 112 located downstream of the impeller 41 of the supercharger 4. Note that the "upstream side" refers to the upstream side in the flow direction of gas flowing through the intake line 11, and the "downstream side" refers to the downstream side in the flow direction of gas flowing through the intake line 11.

[0021] The diesel engine 1 includes a bypass valve 18 provided in the second intake passage 11B and an intercooler 19 provided upstream of the branch portion 111 in the first intake passage 11A. The bypass valve 18 is electrically connected to the control device 2 via wire or wirelessly so as to be able to communicate with the control device 2. The bypass valve 18 has a motor and an actuator (not shown) that operate in response to an opening / closing command (OPEN / CLOSE signal) sent from the control device 2, and is configured to be able to open and close the second intake passage 11B in response to the opening / closing command from the control device 2. The intercooler 19 is a heat exchanger that cools gas passing through the intercooler 19.

[0022] (Diesel engine control method and control device) Fig. 2 is a flow chart showing an example of a control method for a diesel engine according to an embodiment of the present disclosure. Fig. 3 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. 2, a control method 100 for a diesel engine 1 according to some embodiments includes a clutch switching step S101, a fuel injection period control step S102, a fuel injection start timing control step S103, and a bypass valve control step S104. Note that some of the steps in the control method 100 may be performed by the control device 2. Furthermore, some of the steps in the control method 100 may be performed by a device or equipment other than the control device 2, or may be performed manually.

[0023] As shown in FIG. 3, the control device 2 includes a database unit 21, a clutch control unit 22, a fuel injection period control unit 23, a fuel injection start timing control unit 24, and a bypass valve control unit 25.

[0024] The control device 2 is an electronic control unit for controlling the diesel engine 1. The control device 2 is configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, a storage device such as an external storage device, an I / O interface, a communication interface, etc. In one embodiment, the control device 2 is an engine control unit (ECU). The control device 2 may realize each of the above-described parts by the CPU operating (e.g., performing data calculations) according to instructions of a program loaded into the main storage device of the memory, for example.

[0025] In the illustrated embodiment, as shown in FIG. 3 , the diesel engine 1 includes a rotation speed sensor 26 configured to measure the rotation speed NA of the engine 5 and an accelerator sensor 27 configured to measure an accelerator pedal position AA of the engine 5. The control device 2 is electrically connected to the rotation speed sensor 26 and the accelerator sensor 27 via wired or wireless communication. The rotation speed NA measured by the rotation speed sensor 26 and the accelerator pedal position AA measured by the accelerator sensor 27 are sent to the control device 2. The control device 2 is configured to calculate the torque (actual torque) TA of the engine 5 based on input signals from various sensors (such as the rotation speed sensor 26 and the accelerator sensor 27) provided in the diesel engine 1. Note that the control device 2 may acquire the torque TA using a torque sensor (not shown). The database unit 21 stores information acquired by sensors provided in the diesel engine 1 (such as the rotation speed NA and the accelerator pedal position AA) and information calculated based on the information acquired by the sensors (such as the torque TA). Each part of the control device 2 (such as the clutch control part 22, the fuel injection period control part 23, the fuel injection start timing control part 24, and the bypass valve control part 25) is configured to acquire necessary information from the database part 21.

[0026] As shown in FIG. 2, in the control method 100 for the diesel engine 1, the traveling state of the vehicle equipped with the diesel engine 1 changes (S112) in response to a change in the condition of the road on which the vehicle is traveling (S111), and the rotational speed NA of the engine 5 changes (S113) in response to the change in the traveling state of the vehicle (S112). The clutch 16 and the bypass valve 18 described above are switched in response to the change in the rotational speed NA of the engine 5 (S113). In other words, the clutch switching step S101 and the bypass valve control step S104 are performed in response to the change in the rotational speed NA of the engine 5 (S113). As a result, the operating state (drive state or stop state) of the supercharger 4 changes (S114), and the torque TA of the engine 5 changes in response to the change in the operating state of the supercharger 4 (S115), and therefore the traveling state of the vehicle changes (S112).

[0027] As shown in FIG. 2, in order to respond to a change in the vehicle's running state (S112), the driver (operator) operating the vehicle may operate the accelerator (S116). This accelerator operation changes the accelerator opening AA of the engine 5. The fuel injection period TQ and the fuel injection start timing TS are determined according to the changed accelerator opening AA of the engine 5 and the changed rotation speed NA of the engine 5 in step S113 described above. In other words, fuel injection period control step S102 and fuel injection start timing control step S103 are performed according to the change in the accelerator opening AA of the engine 5 and the rotation speed NA of the engine 5. A change in any one of the accelerator opening AA, the fuel injection period TQ, or the fuel injection start timing TS changes the torque TA of the engine 5 (S117), and therefore the running state of the vehicle changes (S112).

[0028] (Clutch switching step) In the clutch switching step S101, the state of the clutch 16 is switched between connected and disconnected. In the illustrated embodiment, the clutch control unit 22 executes the clutch switching step S101. The clutch 16 is electrically connected to the control device 2 via wire or wireless communication. The clutch 16 is configured to be able to change the state of the clutch 16 between connected and disconnected in response to an instruction (clutch ON / OFF signal) from the clutch control unit 22. Specifically, when the signal sent from the clutch control unit 22 to the clutch 16 is switched from an ON signal to an OFF signal, the clutch 16 is switched from the connected state to the disconnected state. Also, when the signal sent from the clutch control unit 22 to the clutch 16 is switched from an OFF signal to an ON signal, the clutch 16 is switched from the disconnected state to the connected state. Note that either the clutch ON / OFF signal may be a signal indicating that the clutch control unit 22 does not send a signal to the clutch 16.

[0029] When the clutch 16 is in an engaged state, power is transmitted from the drive shaft 53 of the engine 5 to the supercharger 4 via the clutch 16, and the supercharger 4 is thereby driven (driven state). When the clutch 16 is in an engaged state, the bypass valve 18 is closed, and the gas flowing through the intake line 11 passes between the branching portion 111 and the junction portion 112 of the first intake flow path 11A, that is, passes through the impeller 41. In other words, when the clutch 16 is in an engaged state, both the turbocharger 3 and the supercharger 4 operate as superchargers. The gas supplied to the engine 5 is supercharged by the compressor 32 of the turbocharger 3 and the supercharger 4.

[0030] When the clutch 16 is in a disengaged state, power is not transmitted from the drive shaft 53 of the engine 5 to the supercharger 4, and therefore the supercharger 4 does not operate (is in a stopped state). When the clutch 16 is in a disengaged state, the bypass valve 18 is open, and the gas flowing through the intake line 11 passes through the second intake flow path 11B. In other words, when the clutch 16 is in an engaged state, only the turbocharger 3 operates as a supercharger. The gas supplied to the engine 5 is compressed by the compressor 32 of the turbocharger 3.

[0031] Fig. 4 is an explanatory diagram for explaining the control of the clutch control unit in one embodiment. Fig. 4 is a graph with the rotation speed NA of the engine 5 on the horizontal axis and the torque TA of the engine 5 on the vertical axis. Fig. 4 also shows a design engine operating line LA1 and a design boundary line BL. As shown in the figure, the boundary line BL divides the engine into a low-flow operating region LR (left side in the figure) where supercharging by the supercharger 4 is required and a normal operating region NR (right side in the figure) where supercharging by the supercharger 4 is not required.

[0032] The clutch control unit 22 switches the state of the clutch 16 depending on the operating state of the engine 5 (at least one of the rotation speed NA and the torque TA). Specifically, when the operating state of the engine 5 shifts from the low flow rate operating region LR to the normal operating region NR, the state of the clutch 16 is switched from the connected state to the disconnected state, and the supercharger 4 is stopped (the supercharger 4 is switched from the driven state to the stopped state). Also, when the operating state of the engine 5 shifts from the normal operating region NR to the low flow rate operating region LR, the state of the clutch 16 is switched from the disconnected state to the connected state, and the supercharger 4 is driven (the supercharger 4 is switched from the stopped state to the driven state).

[0033] In the illustrated embodiment, a set value NA1 (set rotation speed) of the rotation speed of the engine 5 is set in advance as an indicator of the boundary line BL described above. This set value NA1 is stored in the database unit 21 before the clutch switching step S101. The clutch control unit 22 switches the state of the clutch 16 when the rotation speed NA of the engine 5 passes through the set value NA1. Specifically, when the rotation speed NA of the engine 5 passes through the set value NA1 while increasing, the state of the clutch 16 is switched from the connected state to the disconnected state, and the supercharger 4 is stopped. Furthermore, when the rotation speed NA of the engine 5 passes through the set value NA1 while decreasing, the state of the clutch 16 is switched from the disconnected state to the connected state, and the supercharger 4 is driven.

[0034] (Bypass valve control step) In the bypass valve control step S104, when the state of the clutch 16 is switched in the clutch switching step S101, the open / close state of the bypass valve 18 is switched. In the illustrated embodiment, the bypass valve control unit 25 executes the bypass valve control step S104. The bypass valve 18 is configured to be able to change the open / close state of the bypass valve 18 in response to an open / close instruction (OPEN / CLOSE signal) from the bypass valve control unit 25 (control device 2). Specifically, when the signal sent from the bypass valve control unit 25 to the bypass valve 18 is switched from an OPEN signal to a CLOSE signal, the bypass valve 18 is switched from the open state to the closed state. Also, when the signal sent from the bypass valve control unit 25 to the bypass valve 18 is switched from a CLOSE signal to an OPEN signal, the bypass valve 18 is switched from the closed state to the open state. Note that either the OPEN or CLOSE signal may be a signal that the bypass valve control unit 25 does not send a signal to the bypass valve 18.

[0035] The bypass valve control unit 25 instructs the bypass valve 18 to open the bypass valve 18 when the state of the clutch 16 is switched from the engaged state to the disengaged state. Also, the bypass valve control unit 25 instructs the bypass valve 18 to close the bypass valve 18 when the state of the clutch 16 is switched from the disengaged state to the engaged state. Note that the instruction from the bypass valve control unit 25 to the bypass valve 18 may be given after a predetermined period has elapsed since the state of the clutch 16 was switched.

[0036] (Fuel injection period control step) In the fuel injection period control step S102, the fuel injection period TQ is controlled based on first association information 231 that associates in advance the rotation speed NA of the engine 5, the accelerator opening AA, and the fuel injection period TQ to the engine 5. In the illustrated embodiment, the fuel injection period control unit 23 executes the fuel injection period control step S102. The first association information 231 is stored in advance in the database unit 21 before the fuel injection period control step S102. The first association information 231 includes a fuel injection period map 231A in which the fuel injection period TQ is defined according to the rotation speed NA of the engine 5 and the accelerator opening AA.

[0037] FIG. 5 is an explanatory diagram illustrating the control of the fuel injection period control unit in one embodiment. FIG. 5 shows a fuel injection period map 231A with the rotation speed NA of the engine 5 on the horizontal axis and the fuel injection period TQ on the vertical axis. The fuel injection period map 231A shows multiple curves LB1, LB2, and LB3 that indicate the relationship between the rotation speed NA of the engine 5 and the fuel injection period TQ for each accelerator opening AA. The fuel injection period TQ corresponding to the rotation speed NA and accelerator opening AA can be calculated from the position on the fuel injection period map 231A. The fuel injection period control unit 23 uses the fuel injection period map 231A (first association information 231) to calculate the fuel injection period TQ corresponding to the rotation speed NA and accelerator opening AA of the engine 5 and instructs the fuel injection device 13 to inject liquid fuel for the calculated fuel injection period TQ. The fuel injection device 13 injects an amount of liquid fuel corresponding to the fuel injection period TQ.

[0038] 3, the control device 2 further includes a required torque control unit 28. The required torque control unit 28 is configured to calculate the required torque RTA of the engine 5 from the rotation speed NA measured by the rotation speed sensor 26 and the accelerator opening AA measured by the accelerator sensor 27, based on a torque map 281 that previously associates the rotation speed NA of the engine 5, the accelerator opening AA, and the required torque RTA of the engine 5. The fuel injection period control unit 23 described above calculates a fuel injection period TQ suitable for the required torque RTA calculated by the required torque control unit 28.

[0039] Since there is a correlation between the fuel injection period TQ and the fuel injection amount, the fuel injection amount may be used instead of the fuel injection period TQ as a parameter in the fuel injection period control step S102 (fuel injection period control unit 23). Furthermore, the first association information 231 may be any information that can use the engine speed NA and accelerator opening AA of the engine 5 as input information and output the fuel injection period TQ (or fuel injection amount) corresponding to the input information, and may include a list, table, map, function, machine learning model, or the like that indicates the correspondence between the input information and the output information. The first association information 231 may be created based on steady-state test data, or may be created based on past actual values, experimental values, numerical analysis results, or the like other than steady-state test data.

[0040] Fig. 6 is an explanatory diagram for explaining changes in the state of the diesel engine clutch when the state is switched in a comparative example. In Fig. 6, the horizontal axis represents elapsed time T, and the diagram shows changes in the state of the diesel engine 1 when the engine speed NA of the engine 5 passes through a set value NA1 while decreasing. When the engine speed NA of the engine 5 passes through the set value NA1, the clutch control unit 22 switches the state of the clutch 16 from a disengaged state to an engaged state. In Fig. 6, the accelerator opening AA is constant before and after the state of the clutch 16 is switched.

[0041] Switching the state of the clutch 16 in the above-described clutch switching step S101 changes the operating state of the supercharger 4 (S114), and the torque TA of the engine 5 changes in accordance with the change in the operating state of the supercharger 4 (S115). Specifically, as shown in FIG. 6 , when the state of the clutch 16 is switched from the disengaged state to the engaged state, the supercharger 4 enters a driving state, and the gas supplied to the engine 5 is supercharged not only by the compressor 32 but also by the supercharger 4, so that the scavenging pressure SP of the engine 5 rises sharply. Furthermore, because a portion of the power generated by the engine 5 is used for the supercharger 4, the mechanical loss of the engine 5 increases sharply. The sudden change in the scavenging pressure SP and mechanical loss of the engine 5 also causes a sudden change in the fuel economy rate FER of the engine 5. Note that when the state of the clutch 16 is switched from the engaged state to the disengaged state, the supercharger 4 enters a stopped state, the scavenging pressure SP of the engine 5 drops sharply, and the mechanical loss of the engine 5 decreases sharply. In this case as well, the fuel consumption rate FER of the engine 5 changes suddenly due to a sudden change in the scavenging pressure SP or mechanical loss of the engine 5. When the fuel consumption rate FER of the engine 5 changes, the torque TA of the engine 5 also changes.

[0042] FIG. 7 is an explanatory diagram for explaining the control of the fuel injection start timing control unit of the comparative example. FIG. 7 shows a fuel injection start timing control map 0241 with the rotation speed NA of the engine 5 on the horizontal axis and the fuel injection period TQ on the vertical axis. The fuel injection start timing control map 0241 shows multiple curves LC1, LC2, LC3, and LC4 indicating the relationship between the rotation speed NA of the engine 5 and the fuel injection period TQ for each fuel injection start timing TS (injection crank angle) to the engine 5. The fuel injection start timing control unit of the comparative example uses the fuel injection start timing control map 0241 to calculate the fuel injection start timing TS corresponding to the rotation speed NA and fuel injection period TQ of the engine 5 and instructs the fuel injection device 13 to start injecting liquid fuel at the calculated fuel injection start timing TS. Note that, in the control by the fuel injection start timing control unit of the comparative example, when the operating state of the supercharger 4 is switched in response to a change in the rotation speed NA of the engine 5, the fuel injection start timing control map is not switched as described below.

[0043] The control by the fuel injection start timing control unit in the comparative example does not take into consideration the effects of sudden changes in the scavenging pressure SP of the engine 5 or mechanical loss when the operating state of the supercharger 4 is switched. Therefore, as shown in FIG. 6, when the operating state of the supercharger 4 is switched, a change in the torque TA of the engine 5 that is not intended by the driver of the vehicle equipped with the diesel engine 1 may occur (S115), and additional accelerator adjustment by the driver (S116) may be required.

[0044] (Fuel injection start timing control step) In fuel injection start timing control step S103, the fuel injection start timing TS for the engine 5 is controlled based on the control maps 241A, 242A (association information 241, 242) corresponding to the operating state of the supercharger 4. Specifically, fuel injection start timing control step S103 includes a first fuel injection start timing control step of controlling the fuel injection start timing TS based on the control map 241A (association information 241) when the supercharger 4 is in the driving state, and a second fuel injection start timing control step of controlling the fuel injection start timing TS based on the control map 242A (association information 242) when the supercharger 4 is in the stopped state. In the above-mentioned step S113 (see FIG. 2), when the rotation speed NA of the engine 5 passes through the set value NA1, it is determined that the operating state of the supercharger 4 has changed (switched), and the control maps 241A, 242A (association information 241, 242) used for controlling the fuel injection start timing TS are switched. In the illustrated embodiment, the fuel injection start timing control unit 24 executes the fuel injection start timing control step S103. In the illustrated embodiment, the fuel injection start timing control unit 24 calculates the fuel injection start timing TS suitable for the required torque RTA calculated by the required torque control unit 28.

[0045] When switching between the control maps 241A and 242A, the torque TA of the engine 5 can be increased by advancing the fuel injection start time TS to the engine 5. When switching between the control maps 241A and 242A, the torque TA of the engine 5 can be decreased by delaying the fuel injection start time TS to the engine 5. The fuel injection start timing control unit 24 changes the fuel injection start time TS to the engine 5 so that the torque TA of the engine 5 after switching between the control maps 241A and 242A is the same as or the difference between the torque TA of the engine 5 before switching between the control maps 241A and 242A is small. Note that the fuel injection start timing control unit 24 may change the fuel injection start time TS to the engine 5 so that the fuel efficiency rate FER of the engine 5 after switching between the control maps 241A and 242A is the same as or the difference between the fuel efficiency rate FER of the engine 5 before switching between the control maps 241A and 242A is small. In addition, the fuel injection start timing control unit 24 may change the fuel injection start timing TS to the engine 5 so that the scavenging pressure SP of the engine 5 after switching between the control maps 241A and 242A is the same as or has a small difference from the scavenging pressure SP of the engine 5 before switching between the control maps 241A and 242A.

[0046] In the above-described fuel injection period control unit 23 (fuel injection period control step S102), not only the fuel injection period TQ but also the fuel injection start timing TS corresponding to the fuel injection period TQ may be determined. In the above-described fuel injection start timing control unit 24 (fuel injection start timing control step S103), the fuel injection start timing TS determined in the fuel injection period control unit 23 (fuel injection period control step S102) may be corrected, or may be changed to the fuel injection start timing TS determined in the fuel injection start timing control unit 24 (fuel injection start timing control step S103).

[0047] 2, a control method 100 for a diesel engine 1 according to some embodiments includes the above-described clutch switching step S101, the above-described fuel injection period control step S102, and the above-described fuel injection start timing control step S103. The fuel injection start timing control step S103 includes the above-described first fuel injection start timing control step and the above-described second fuel injection start timing control step.

[0048] According to the above method, in the fuel injection start timing control step S103, the fuel injection start timing TS is controlled based on the association information (second association information 241, third association information 242) that differs depending on the operation state (drive state or stop state) of the supercharger (4), thereby making it possible to make the fuel injection start timing TS appropriate for the operation state of the supercharger 4. In the fuel injection start timing control step S103, the fuel consumption rate FER and the torque TA of the engine 5 can be changed by changing the fuel injection start timing TS of the engine 5. In the fuel injection start timing control step S103, the fuel injection start timing TS of the engine 5 is changed so that the fuel consumption rate FER and the torque TA of the engine 5 after a change in the operation state of the supercharger 4 are the same as or have a small difference from the fuel consumption rate FER and the torque TA of the engine 5 before the change in the operation state of the supercharger 4, thereby suppressing fluctuations in the fuel consumption rate FER and the torque TA of the engine 5 that may occur when the operation state of the supercharger 4 changes. By suppressing fluctuations in the fuel economy rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes, the driver does not need to adjust the accelerator to keep the torque TA constant. Furthermore, according to the above method, there is no need to change the control of the fuel injection period TQ in the fuel injection period control step S102, so the control method 100 can be prevented from becoming complicated.

[0049] As shown in Fig. 3, a control device 2 for a diesel engine 1 according to some embodiments includes the above-described clutch control unit 22, the above-described fuel injection period control unit 23, and the above-described fuel injection start timing control unit 24. The above-described control device 2 has second association information 241 that associates in advance the engine speed NA, fuel injection period TQ, and fuel injection start timing TS when the supercharger 4 is in a driving state, and third association information 242 that associates in advance the engine speed NA, fuel injection period TQ, and fuel injection start timing TS when the supercharger 4 is in a stopped state. The third association information 242 is information different from the second association information 241.

[0050] The second association information 241 and the third association information 242 are stored in advance in the database unit 21 before the fuel injection start timing control step S103. The second association information 241 includes a first fuel injection start timing control map 241A that defines the fuel injection start timing TS corresponding to the engine speed NA and fuel injection period TQ when the supercharger 4 is in a driving state. The third association information 242 includes a second fuel injection start timing control map 242A that defines the fuel injection start timing TS corresponding to the engine speed NA and fuel injection period TQ when the supercharger 4 is in a stopped state. The second fuel injection start timing control map 242A is a different map from the first fuel injection start timing control map 241A.

[0051] The above-mentioned fuel injection start timing control unit 24 is configured to control the fuel injection start timing TS based on the second association information 241 when it is determined that the supercharger 4 is in a driving state, and is configured to control the fuel injection start timing TS based on the third association information 242 when it is determined that the supercharger 4 is in a stopped state.

[0052] Fig. 8 is an explanatory diagram for explaining the control of the fuel injection start timing control unit in one embodiment. Fig. 8 shows two fuel injection start timing control maps 241A and 242A, with the rotation speed NA of the engine 5 on the horizontal axis and the fuel injection period TQ on the vertical axis. The first fuel injection start timing control map 241A shows multiple curves LD1, LD2, LD3, and LD4 that indicate the relationship between the rotation speed NA of the engine 5 and the fuel injection period TQ for each fuel injection start timing TS (injection crank angle) into the engine 5. The second fuel injection start timing control map 242A shows multiple curves LE1, LE2, LE3, and LE4 that indicate the relationship between the rotation speed NA of the engine 5 and the fuel injection period TQ for each fuel injection start timing TS (injection crank angle) into the engine 5.

[0053] When the fuel injection start timing control unit 24 determines that the supercharger 4 is in a driving state, it calculates the fuel injection start timing TS corresponding to the engine speed NA and fuel injection period TQ from the engine speed NA and fuel injection period TQ based on the position on the first fuel injection start timing control map 241A. When the fuel injection start timing control unit 24 determines that the supercharger 4 is in a stopped state, it calculates the fuel injection start timing TS corresponding to the engine speed NA and fuel injection period TQ from the engine speed NA and fuel injection period TQ based on the position on the second fuel injection start timing control map 242A. The fuel injection start timing control unit 24 calculates the fuel injection start timing TS corresponding to the engine speed NA and fuel injection period TQ using control maps 241A, 242A that differ depending on the operating state of the supercharger 4, and instructs the fuel injection device 13 to start injecting liquid fuel at the calculated fuel injection start timing TS.

[0054] The second fuel injection start timing control map 242A (third association information 242) is set so that when the supercharger 4 switches its operating state (for example, when the rotation speed NA is equal to the set value NA1), at least one of the torque TA, fuel consumption rate FER, and scavenging pressure SP of the engine 5 is the same as or has a small difference from the first fuel injection start timing control map 241A (second association information 241).

[0055] Since there is a correlation between the fuel injection period TQ and the fuel injection amount, the fuel injection amount may be used instead of the fuel injection period TQ as a parameter in the fuel injection start timing control step S103 (fuel injection start timing control unit 24). The second association information 241 and the third association information 242 may be any information that can use the engine speed NA and the fuel injection period TQ (or the fuel injection amount) of the engine 5 as input information and output the fuel injection start timing TS corresponding to the input information, and may include a list, table, map, function, machine learning model, or the like that indicates the correspondence between the input information and the output information. The second association information 241 and the third association information 242 may be created based on steady-state test data, or may be created based on past performance values, experimental values, numerical analysis results, or the like other than steady-state test data.

[0056] According to the above configuration, the fuel injection start timing control unit 24 controls the fuel injection start timing TS based on the association information 241, 242, which differs depending on the operating state (drive state or stop state) of the supercharger 4 determined by the fuel injection start timing control unit 24, thereby making the fuel injection start timing TS appropriate for the operating state of the supercharger 4. The fuel injection start timing control unit 24 changes the fuel injection start timing TS of the engine 5, thereby changing the fuel economy FER and torque TA of the engine 5. The fuel injection start timing control unit 24 changes the fuel injection start timing TS of the engine 5 so that the fuel economy FER and torque TA of the engine 5 after a change in the operating state of the supercharger 4 become the same as the fuel economy FER and torque TA of the engine before the change in the operating state of the supercharger 4, thereby suppressing fluctuations in the fuel economy FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes. Suppressing fluctuations in the fuel economy FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes eliminates the need for the driver to adjust the accelerator to keep the torque TA constant. Furthermore, with the above configuration, it is not necessary to change the control of the fuel injection period TQ by the fuel injection period control unit 23, and therefore the control in the control device 2 can be prevented from becoming complicated.

[0057] In some embodiments, the second association information 241 described above includes a first fuel injection start timing control map 241A in which the fuel injection start timing TS is defined in accordance with the engine speed NA and the fuel injection period TQ. The third association information 242 described above includes a second fuel injection start timing control map 242A in which the fuel injection start timing TS is defined in accordance with the engine speed NA and the fuel injection period TQ. The second fuel injection start timing control map 242A is a map different from the first fuel injection start timing control map 241A.

[0058] According to the above configuration, the fuel injection start timing control unit 24 controls the fuel injection start timing TS based on the control maps 241A, 242A, which differ depending on the operating state (drive state or stop state) of the supercharger 4 determined by the fuel injection start timing control unit 24, thereby making it possible to make the fuel injection start timing TS appropriate for the operating state of the supercharger 4 and effectively suppress fluctuations in the fuel consumption rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes. Furthermore, by controlling the fuel injection start timing TS by a mapping method using the control maps 241A, 242A, the fuel injection start timing control unit 24 can suppress an increase in the complexity of control, and ultimately suppress an increase in the complexity of control in the control device 2.

[0059] (Method 1 for determining the operation status of the supercharger) In some embodiments, in the above-described control method 100, the control maps 241A, 242A referred to in the fuel injection start timing control step S103 are switched in accordance with a change in the rotation speed NA of the engine 5 in step S113, as shown by the dashed line in Fig. 2. The above-described fuel injection start timing control unit 24 switches between the control maps 241A, 242A used to control the fuel injection start timing TS in accordance with a change in the rotation speed NA of the engine 5 measured by the rotation speed sensor 26, as shown by the dashed line in Fig. 3.

[0060] 3, the above-described fuel injection start timing control unit 24 is configured to take in the rotation speed NA of the engine 5 as an index for determining the operating state of the supercharger 4, and determine that the operating state of the supercharger 4 has changed when the rotation speed NA of the engine 5 passes through a set value NA1. In this embodiment, the fuel injection start timing control unit 24 (fuel injection start timing control step S103) determines that the operating state of the supercharger 4 has changed when the rotation speed NA of the engine 5 passes through the set value NA1, and switches the control maps 241A, 242A (association information 241, 242) used for controlling the fuel injection start timing TS. According to the above configuration, the time delay from when the clutch control unit 22 issues an instruction to the clutch 16 to switch the state of the clutch 16 to when the switching of the operating state (drive state or stopped state) of the supercharger 4 is completed (for example, from when the clutch 16 is connected until the supercharger 4 begins to rotate without slippage in accordance with the rotation speed NA of the engine 5) is not taken into consideration, so there is a risk of a time difference occurring between when the control maps 241A, 242A are switched and when the state of the supercharger 4 is switched, compared to the method of determining the operating state of the supercharger 4 described below.

[0061] (Method 2 for determining the operation status of the supercharger) Fig. 9 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. Fig. 10 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. In some embodiments, the control maps 241A, 242A referred to in the fuel injection start timing control step S103 are switched in accordance with a change in the state (engaged state or disengaged state) of the clutch 16 in the above-described clutch switching step S101, as shown by the dashed line in Fig. 9. The above-described fuel injection start timing control unit 24 switches between the control maps 241A, 242A used to control the fuel injection start timing TS in accordance with a change in the instruction signal (clutch ON / OFF signal) sent from the clutch control unit 22 of the control device 2 to the clutch 16, as shown by the dashed line in Fig. 10.

[0062] In the embodiment shown in Fig. 10, the above-mentioned control device 2 is configured to be able to send a signal from the clutch control unit 22 to the clutch 16 instructing whether the clutch 16 is engaged or disengaged. As indicated by the dashed dotted line in Fig. 10, the above-mentioned fuel injection start timing control unit 24 is configured to take in the instruction signal from the clutch control unit 22 to the clutch 16 as an index for determining the operating state of the supercharger 4, and to determine that the operating state of the supercharger 4 has changed in accordance with the signal that the clutch control unit 22 of the control device 2 has issued to the clutch 16. In this embodiment, the fuel injection start timing control unit 24 (fuel injection start timing control step S103) determines that the operating state of the supercharger 4 has changed when the instruction signal from the clutch control unit 22 to the clutch 16 is switched, and switches the control maps 241A, 242A used for controlling the fuel injection start timing TS.

[0063] FIG. 11 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. In FIG. 11, the horizontal axis represents elapsed time T, and the vertical axis represents an instruction signal (clutch ON / OFF signal) sent from the clutch control unit 22 of the control device 2 to the clutch 16, showing changes in the instruction signal over time. When the instruction signal sent from the clutch control unit 22 to the clutch 16 changes from an ON signal to an OFF signal (T1 in the figure), the fuel injection start timing control unit 24 determines that the operating state of the supercharger 4 has been switched from a driven state to a stopped state, and switches the control map used for controlling the fuel injection start timing TS from 241A to 242A. When the instruction signal sent from the clutch control unit 22 to the clutch 16 changes from an OFF signal to an ON signal (T2 in the figure), the fuel injection start timing control unit 24 determines that the operating state of the supercharger 4 has been switched from a stopped state to a driven state, and switches the control map used for controlling the fuel injection start timing TS from 242A to 241A.

[0064] According to the above configuration, the command signal sent from the control device 2 to the clutch 16 differs depending on whether the supercharger 4 is in a driving state or a stopped state. By determining that the operating state of the supercharger 4 has changed in response to the command signal from the control device 2 to the clutch 16, the fuel injection start timing control unit 24 switches the control of the fuel injection start timing TS (switches the control maps 241A, 242A used for control) at a more appropriate time that takes into account the time delay when the operating state of the supercharger 4 (driving state or stopped state) is switched, compared to when the operating state of the supercharger 4 is determined to have changed based on the rotational speed NA of the engine 5. This reduces the time difference that may occur between the time when the control of the fuel injection start timing TS is switched and the time when the operating state of the supercharger 4 is switched. As a result, the fuel injection start timing control unit 24 can make the fuel injection start timing TS more appropriate both before and after a change in the operating state of the supercharger 4, thereby more effectively suppressing fluctuations in the fuel consumption rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes.

[0065] (Method 3 for determining the operation status of the supercharger) FIG. 12 is a flowchart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. In some embodiments, in the above-described control method 100, the control maps 241A, 242A referenced in the fuel injection start timing control step S103 are switched in accordance with a change in the state (open state or closed state) of the bypass valve 18 in the bypass valve control step S104, as shown by the dashed line in Fig. 9. The above-described fuel injection start timing control unit 24 switches the control maps 241A, 242A used to control the fuel injection start timing TS in accordance with a change in the opening / closing command (OPEN / CLOSE signal) sent from the bypass valve control unit 25 of the control device 2 to the bypass valve 18, as shown by the dashed line in Fig. 12.

[0066] 12, the above-described control device 2 is configured to be able to send a signal from the bypass valve control unit 25 to the bypass valve 18 instructing it to open or close the bypass valve 18. As indicated by the dashed dotted line in FIG. 12, the above-described fuel injection start timing control unit 24 is configured to take in the instruction signal from the bypass valve control unit 25 to the bypass valve 18 as an index for determining the operating state of the supercharger 4, and to determine that the operating state of the supercharger 4 has changed in accordance with the signal that the bypass valve control unit 25 of the control device 2 has sent to the bypass valve 18. In this embodiment, the fuel injection start timing control unit 24 (fuel injection start timing control step S103) determines that the operating state of the supercharger 4 has changed when the instruction signal from the bypass valve control unit 25 to the bypass valve 18 is switched, and switches the control maps 241A and 242A used for controlling the fuel injection start timing TS.

[0067] FIG. 13 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. In FIG. 13, the horizontal axis represents elapsed time T, and the vertical axis represents the command signal (OPEN / CLOSE signal) sent from the bypass valve control unit 25 of the control device 2 to the bypass valve 18, showing changes in the command signal over time. When the command signal sent from the bypass valve control unit 25 to the bypass valve 18 changes from a CLOSE signal to an OPEN signal (T3 in the figure), the fuel injection start timing control unit 24 determines that the operating state of the supercharger 4 has been switched from a driven state to a stopped state, and switches the control map used for controlling the fuel injection start timing TS from 241A to 242A. When the command signal sent from the bypass valve control unit 25 to the bypass valve 18 changes from an OPEN signal to a CLOSE signal (T4 in the figure), the fuel injection start timing control unit 24 determines that the operating state of the supercharger 4 has been switched from a stopped state to a driven state, and switches the control map used for controlling the fuel injection start timing TS from 242A to 241A.

[0068] According to the above configuration, the instruction signal sent from the control device 2 to the bypass valve 18 differs depending on whether the supercharger 4 is in a driven state or a stopped state. By determining that the operating state of the supercharger 4 has changed in response to the instruction signal from the control device 2 to the bypass valve 18, the fuel injection start timing control unit 24 switches the control of the fuel injection start timing TS (switches the control maps 241A and 242A) at a more appropriate time that takes into account the time delay when the operating state of the supercharger 4 (driven state or stopped state) is switched, compared to when the operating state of the supercharger 4 is determined to have changed based on the rotational speed NA of the engine 5. This reduces the time difference that may occur between the time when the control of the fuel injection start timing TS is switched and the time when the operating state of the supercharger 4 is switched. As a result, the fuel injection start timing control unit 24 can make the fuel injection start timing TS more appropriate both before and after a change in the operating state of the supercharger 4, and more effectively suppress fluctuations in the fuel consumption rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes.

[0069] (Method 4 for determining the operation status of the supercharger) Fig. 14 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. Fig. 15 is a flow chart illustrating an example of a control method for a diesel engine according to an embodiment of the present disclosure. In some embodiments, the above-described control device 2 further includes a supercharger rotation speed acquisition device 6 configured to acquire the rotation speed N B of the supercharger 4, as shown in Fig. 15. In the illustrated embodiment, as shown in Figs. 1 and 15, the supercharger rotation speed acquisition device 6 includes a rotation speed sensor 61 configured to measure the rotation speed N B of the supercharger 4. In the embodiment shown in Fig. 1, the rotation speed sensor 61 detects the rotation speed of the rotating shaft 43.

[0070] In the above-described control method 100, the fuel injection start timing control maps 241A, 242A referenced in the fuel injection start timing control step S103 are switched in accordance with a change in the operating state of the supercharger 4 (specifically, the rotation speed N B of the supercharger 4 acquired by the supercharger rotation speed acquisition device 6) in the above-described step S114, as shown by the dashed-dotted line in Fig. 14. The above-described fuel injection start timing control unit 24 switches the control maps 241A, 242A used to control the fuel injection start timing TS in accordance with a change in the rotation speed N B of the supercharger 4 measured by the rotation speed sensor 61, as shown by the dashed-dotted line in Fig. 15.

[0071] 15, the above-described fuel injection start timing control unit 24 is configured to take in the rotation speed NB of the supercharger 4 as an index for determining the operating state of the supercharger 4, and to determine that the operating state of the supercharger 4 has changed based on a preset threshold value RNB of the rotation speed NB of the supercharger 4 and the rotation speed NB of the supercharger 4 acquired by the supercharger rotation speed acquisition device 6. In this embodiment, the fuel injection start timing control unit 24 (fuel injection start timing control step S103) determines that the operating state of the supercharger 4 has changed when the rotation speed NB of the supercharger 4 acquired by the supercharger rotation speed acquisition device 6 exceeds the threshold value RNB, and switches the control maps 241A and 242A used for controlling the fuel injection start timing TS.

[0072] FIG. 16 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. In FIG. 16, the horizontal axis represents elapsed time T, the vertical axis represents the rotation speed NB of the supercharger 4, and the change in the rotation speed NB (acquired rotation speed) acquired by the supercharger rotation speed acquisition device 6 is shown. As shown in FIG. 16, immediately after the clutch 16 is engaged, slippage of the clutch 16 occurs, causing the rotation speed NB of the supercharger 4 to increase gradually. Then, as the slippage of the clutch 16 disappears, the rotation speed NB of the supercharger 4 increases. The threshold value RNB is preset to a value corresponding to the rotation speed NB of the supercharger 4 when the clutch 16 no longer slips and the supercharger 4 rotates in response to the rotation of the engine 5. When the rotation speed NB acquired by the supercharger rotation speed acquisition device 6 exceeds the threshold value RNB (T5 in the figure), the fuel injection start timing control unit 24 determines that the operation state of the supercharger 4 has been switched from a stopped state to a driven state, and switches the control map used for controlling the fuel injection start timing TS from 242A to 241A. Also, when the rotation speed NB acquired by the supercharger rotation speed acquisition device 6 falls below the threshold value RNB, the fuel injection start timing control unit 24 determines that the operation state of the supercharger 4 has been switched from a driven state to a stopped state, and switches the control map used for controlling the fuel injection start timing TS from 241A to 242A.

[0073] According to the above configuration, the fuel injection start timing control unit 24 determines that the operating state of the supercharger 4 has changed based on the rotational speed NB of the supercharger 4 acquired by the supercharger rotational speed acquisition device 6. In this case, compared to when the operating state of the supercharger 4 has changed based on the rotational speed NA of the engine 5, the control of the fuel injection start timing TS is switched at a more appropriate time that takes into account the time delay when the operating state (drive state or stop state) of the supercharger 4 is switched. This makes it possible to reduce the time difference that may occur between the time when the control of the fuel injection start timing TS is switched and the time when the state of the supercharger 4 is switched. As a result, the fuel injection start timing control unit 24 can make the fuel injection start timing TS more appropriate both before and after a change in the operating state of the supercharger 4, and can more effectively suppress fluctuations in the fuel consumption rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes.

[0074] (Method 5 for determining the operation status of the supercharger) FIG. 17 is an explanatory diagram for explaining functions of a control device for a diesel engine according to an embodiment of the present disclosure. In some embodiments, the above-described control device 2 further includes a supercharger pressure ratio acquisition device 7 configured to acquire the pressure ratio PR of the supercharger 4, as shown in Fig. 17. In the illustrated embodiment, as shown in Figs. 1 and 17, the supercharger pressure ratio acquisition device 7 includes an inlet pressure sensor 71 configured to measure the inlet pressure of the supercharger 4 and an outlet pressure sensor 72 configured to measure the outlet pressure of the supercharger 4. As shown in Fig. 17, the supercharger pressure ratio acquisition device 7 further includes a supercharger pressure ratio derivation unit 73 configured to calculate the pressure ratio PR of the supercharger 4 from the inlet pressure of the supercharger 4 measured by the inlet pressure sensor 71 and the outlet pressure measured by the outlet pressure sensor 72.

[0075] 1, the inlet pressure sensor 71 measures the pressure of the intake air flowing downstream of the branch point 111 of the first intake air flow path 11A and upstream of the impeller 41. The outlet pressure sensor 72 measures the pressure of the first intake air flow path 11A downstream of the impeller 41. Note that the outlet pressure sensor 72 may measure the pressure of the intake air flowing upstream of the junction 112 of the first intake air flow path 11A, or may measure the pressure of the intake air flowing downstream of the junction 112 of the first intake air flow path 11A.

[0076] In the above-described control method 100, the fuel injection start timing control maps 241A, 242A referred to in the fuel injection start timing control step S103 are switched in accordance with a change in the operating state of the supercharger 4 (specifically, the pressure ratio PR of the supercharger 4 acquired by the supercharger pressure ratio acquisition device 7) in the above-described step S114, as shown by the dashed-dotted line in Fig. 14. The above-described fuel injection start timing control unit 24 switches the control maps 241A, 242A used to control the fuel injection start timing TS in accordance with a change in the pressure ratio PR of the supercharger 4 acquired by the supercharger pressure ratio acquisition device 7, as shown by the dashed-dotted line in Fig. 17.

[0077] 17, the above-described fuel injection start timing control unit 24 is configured to take in the pressure ratio PR of the supercharger 4 as an index for determining the operating state of the supercharger 4, and to determine that the clutch 16 has been switched, based on a preset threshold value RPR of the pressure ratio PR of the supercharger 4 and the pressure ratio PR of the supercharger 4 acquired by the supercharger pressure ratio acquisition device 7. In this embodiment, the fuel injection start timing control unit 24 (fuel injection start timing control step S103) determines that the operating state of the supercharger 4 has changed when the pressure ratio PR of the supercharger 4 acquired by the supercharger pressure ratio acquisition device 7 exceeds the threshold value RPR, and switches the control maps 241A, 242A used for controlling the fuel injection start timing TS.

[0078] FIG. 18 is an explanatory diagram for explaining a method for determining the operating state of a supercharger in one embodiment. In FIG. 18, the horizontal axis represents elapsed time T, the vertical axis represents the pressure ratio PR of the supercharger 4, and the change in the pressure ratio PR (acquired pressure ratio) acquired by the supercharger pressure ratio acquisition device 7 is shown. As shown in FIG. 18, immediately after the clutch 16 is engaged, slippage of the clutch 16 occurs, causing the rotation speed NB of the supercharger 4 to increase gradually, and the pressure ratio PR increases in accordance with the increase in the rotation speed NB. Then, as the slippage of the clutch 16 disappears, the rotation speed NB and the pressure ratio PR of the supercharger 4 increase. The threshold value RPR is preset to a value corresponding to the pressure ratio PR of the supercharger 4 when the clutch 16 no longer slips and the supercharger 4 rotates in accordance with the rotation of the engine 5. When the pressure ratio PR acquired by the supercharger pressure ratio acquisition device 7 exceeds the threshold value RPR (T6 in the figure), the fuel injection start timing control unit 24 determines that the operation state of the supercharger 4 has been switched from a stopped state to a driven state, and switches the control map used for controlling the fuel injection start timing TS from 242A to 241A. Also, when the pressure ratio PR acquired by the supercharger pressure ratio acquisition device 7 falls below the threshold value RPR, the fuel injection start timing control unit 24 determines that the operation state of the supercharger 4 has been switched from a driven state to a stopped state, and switches the control map used for controlling the fuel injection start timing TS from 241A to 242A.

[0079] According to the above configuration, the fuel injection start timing control unit 24 determines that the operating state of the supercharger 4 has changed based on the pressure ratio PR of the supercharger 4 acquired by the supercharger pressure ratio acquisition device 7. In this case, compared to when the operating state of the supercharger 4 has changed based on the rotational speed NA of the engine 5, the control of the fuel injection start timing TS is switched at a more appropriate time that takes into account the time delay when the operating state (drive state or stop state) of the supercharger 4 is switched. This makes it possible to reduce the time difference that may occur between the time when the control of the fuel injection start timing TS is switched and the time when the state of the supercharger 4 is switched. As a result, the fuel injection start timing control unit 24 can make the fuel injection start timing TS more appropriate both before and after a change in the operating state of the supercharger 4, and can more effectively suppress fluctuations in the fuel consumption rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes.

[0080] As shown in Fig. 1, a diesel engine 1 according to some embodiments includes the above-described control device 2. With the above configuration, the diesel engine 1 can suppress fluctuations in the fuel economy rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes, while suppressing the complexity of control in the control device 2. By suppressing fluctuations in the fuel economy rate FER and torque TA of the engine 5 that may occur when the operating state of the supercharger 4 changes, it becomes unnecessary for the driver to adjust the accelerator to keep the torque TA constant.

[0081] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0082] The contents of the above-described embodiments can be understood, for example, as follows.

[0083] 1) A control device (2) for a diesel engine (1) according to at least one embodiment of the present disclosure includes: A control device (2) for a diesel engine (1) equipped with a turbocharger (3) and a supercharger (4) as superchargers, a clutch control unit (22) that switches between an engaged and disengaged state of a clutch (16) interposed between a drive shaft (53) of the engine and the supercharger (4); a fuel injection period control unit (23) that controls the fuel injection period (TQ) based on first association information (231) that associates in advance the engine speed (NA), accelerator opening (AA), and fuel injection period (TQ) to the engine; a fuel injection start timing control unit (24) that controls a fuel injection start timing (TS) for the engine, The control device (2) second association information (241) in which the engine speed (NA), the fuel injection period (TQ), and the fuel injection start timing (TS) are associated in advance when the supercharger (4) is in a driving state; and third association information (242) that associates in advance the engine speed (NA), the fuel injection period (TQ), and the fuel injection start timing (TS) when the supercharger (4) is stopped, the third association information (242) being different from the second association information (241), The fuel injection start timing control section (24) When the supercharger (4) is in a driving state, the fuel injection start timing (TS) is controlled based on the second association information (241), and when the supercharger (4) is in a stopped state, the fuel injection start timing (TS) is controlled based on the third association information (242).

[0084] According to the above configuration 1), the fuel injection start timing control unit (24) changes the fuel injection start timing (TS) of the engine, thereby changing the fuel efficiency and torque of the engine. The fuel injection start timing control unit (24) changes the fuel injection start timing (TS) of the engine so that the fuel efficiency and torque of the engine after the state of the clutch (16) is switched become the same as the fuel efficiency and torque of the engine before the state of the clutch (16) is switched. This makes it possible to suppress fluctuations in the fuel efficiency and torque of the engine that may occur when the state of the clutch (16) is switched. Suppressing fluctuations in the fuel efficiency and torque of the engine that may occur when the state of the clutch (16) is switched eliminates the need for the driver to adjust the accelerator to keep the torque constant. Furthermore, according to the above configuration 1), it is not necessary to change the control of the fuel injection period (TQ) by the fuel injection period control unit (23), and therefore the control in the control device (2) can be prevented from becoming complicated.

[0085] According to the configuration 1), the fuel injection start timing control unit (24) controls the fuel injection start timing (TS) based on the association information (second association information 241, third association information 242) that differs depending on the operation state (drive state or stop state) of the supercharger (4), thereby making the fuel injection start timing (TS) appropriate for the operation state of the supercharger (4). The fuel injection start timing control unit (24) changes the fuel injection start timing (TS) of the engine, thereby changing the fuel economy and torque of the engine. The fuel injection start timing control unit (24) changes the fuel injection start timing (TS) of the engine so that the fuel economy and torque of the engine after a change in the operation state of the supercharger (4) become the same as the fuel economy and torque of the engine before the change in the operation state of the supercharger (4), thereby suppressing fluctuations in the fuel economy and torque of the engine that may occur when the operation state of the supercharger (4) changes. By suppressing the fluctuations in the fuel consumption rate and torque of the engine that may occur when the operating state of the supercharger (4) changes, the driver does not need to adjust the accelerator to keep the torque constant. Furthermore, according to the configuration 1), it is not necessary to change the control of the fuel injection period (TQ) by the fuel injection period control unit (23), and therefore the control by the control device (2) can be prevented from becoming complicated.

[0086] 2) In some embodiments, the control device (2) for the diesel engine (1) described in 1) above, the second association information (241) includes a first fuel injection start timing control map (241A) in which the fuel injection start timing (TS) is defined according to the engine speed (NA) and the fuel injection period (TQ), The third association information (242) includes a second fuel injection start timing control map (242A) in which the fuel injection start timing (TS) is defined according to the engine speed (NA) and the fuel injection period (TQ).

[0087] According to the configuration 2), the fuel injection start timing control unit (24) controls the fuel injection start timing (TS) based on fuel injection start timing control maps (first fuel injection start timing control map 241A, second fuel injection start timing control map 242A) that differ for each operation state (drive state or stop state) of the supercharger (4). This makes it possible to make the fuel injection start timing (TS) appropriate for the operation state of the supercharger (4), and effectively suppress fluctuations in the fuel efficiency and torque of the engine that may occur when the operation state of the supercharger (4) changes. Furthermore, the fuel injection start timing control unit (24) controls the fuel injection start timing (TS) by a mapping method using the fuel injection start timing control maps (241A, 242A), thereby suppressing the complexity of control in the fuel injection start timing control unit (24), and thereby suppressing the complexity of control in the control device (2).

[0088] 3) In some embodiments, the control device (2) for the diesel engine (1) described in 1) or 2) above, the control device (2) is configured to be able to send a signal to the clutch (16) instructing whether the clutch (16) is engaged or disengaged; The fuel injection start timing control unit (24) is configured to determine that the operating state of the supercharger (4) has changed in response to a signal sent from the control device (2) to the clutch (16).

[0089] According to the configuration 3), the fuel injection start timing control unit (24) determines that the operating state of the supercharger (4) has changed in response to a signal from the clutch (16), and thereby switches the control of the fuel injection start timing (TS) at a more appropriate time that takes into consideration the time delay at the time of switching the operating state (drive state or stop state) of the supercharger (4), compared to when the change in the operating state of the supercharger (4) is determined based on the engine speed (NA). This allows the fuel injection start timing control unit (24) to make the fuel injection start timing (TS) more appropriate both before and after the change in the operating state of the supercharger (4), and more effectively suppresses fluctuations in the fuel efficiency and torque of the engine that may occur when the operating state of the supercharger (4) changes.

[0090] 4) In some embodiments, the control device (2) for the diesel engine (1) described in 1) or 2) above, the control device (2) is configured to be capable of transmitting a signal to a bypass valve (18) configured to open or close a bypass flow path (11B) that bypasses the supercharger (4) and connects a compressor (32) of the turbocharger (3) and the engine (5), the signal instructing the bypass valve (18) to open or close the bypass flow path (11B); The fuel injection start timing control unit (24) is configured to determine that the operating state of the supercharger (4) has changed in response to a signal sent from the control device (2) to the bypass valve (18).

[0091] According to the configuration 4), the fuel injection start timing control unit (24) determines that the operating state of the supercharger (4) has changed in response to an instruction signal from the control device (2) to the bypass valve (18). This allows the fuel injection start timing control unit (24) to switch the control of the fuel injection start timing (TS) at a more appropriate time, taking into consideration the time delay at the time of switching the operating state (drive state or stop state) of the supercharger (4), compared to when the change in the operating state of the supercharger (4) is determined based on the rotational speed (NA) of the engine (5). This reduces the time difference that may occur between the time of switching the control of the fuel injection start timing TS and the time of switching the operating state of the supercharger (4). This allows the fuel injection start timing control unit (24) to make the fuel injection start timing (TS) more appropriate both before and after the change in the operating state of the supercharger (4). This makes it possible to more effectively suppress fluctuations in the fuel economy (FER) and torque (TA) of the engine (5) that may occur when the operating state of the supercharger (4) changes.

[0092] 5) In some embodiments, the control device (2) for the diesel engine (1) described in 1) or 2) above, The engine further includes a supercharger rotation speed acquisition device (6) configured to acquire a rotation speed (NB) of the supercharger (4), The fuel injection start timing control section (24) The supercharger rotational speed acquisition device (6) is configured to determine whether the operating state of the supercharger (4) has changed, depending on the rotational speed (NB) of the supercharger (4) acquired by the supercharger rotational speed acquisition device (6).

[0093] According to the configuration of 5), the fuel injection start timing control unit (24) determines that the operating state of the supercharger (4) has changed based on the rotational speed (NB) of the supercharger (4) acquired by the supercharger rotational speed acquisition device (6). In this case, the control of the fuel injection start timing (TS) is switched at a more appropriate time in consideration of the time delay at the time of switching the operating state (drive state or stop state) of the supercharger (4), compared to when the operating state of the supercharger (4) has changed based on the rotational speed (NA) of the engine. This allows the fuel injection start timing control unit (24) to make the fuel injection start timing (TS) more appropriate both before and after the change in the operating state of the supercharger (4), thereby more effectively suppressing fluctuations in the fuel efficiency and torque of the engine that may occur when the operating state of the supercharger (4) changes.

[0094] 6) In some embodiments, the control device (2) for the diesel engine (1) described in 1) or 2) above, The system further includes a supercharger pressure ratio acquisition device (7) configured to acquire a pressure ratio (PR) of the supercharger (4), The fuel injection start timing control section (24) The apparatus is configured to determine whether the operating state of the supercharger (4) has changed, depending on the pressure ratio (PR) of the supercharger (4) acquired by the supercharger pressure ratio acquisition device (7).

[0095] According to the configuration of 6), the fuel injection start timing control unit (24) determines that the operating state of the supercharger (4) has changed in accordance with the pressure ratio (PR) of the supercharger (4) acquired by the supercharger pressure ratio acquisition device (7). In this case, the control of the fuel injection start timing (TS) is switched at a more appropriate time in consideration of the time delay at the time of switching the operating state (drive state or stop state) of the supercharger (4), compared to when the operating state of the supercharger (4) is determined in accordance with the engine speed (NA). This allows the fuel injection start timing control unit (24) to make the fuel injection start timing (TS) more appropriate both before and after the change in the operating state of the supercharger (4), thereby more effectively suppressing fluctuations in the fuel economy and torque of the engine that may occur when the operating state of the supercharger (4) changes.

[0096] 7) A diesel engine (1) according to at least one embodiment of the present disclosure, The control device (2) for a diesel engine (1) according to any one of 1) to 6) above is provided.

[0097] According to the configuration of 7), the diesel engine (1) can suppress fluctuations in the fuel economy rate and torque of the engine that may occur when the operating state of the supercharger (4) changes, while suppressing the complexity of the control in the diesel engine control device (2). By suppressing fluctuations in the fuel economy rate and torque of the engine that may occur when the operating state of the supercharger (4) changes, the driver does not need to adjust the accelerator to keep the torque constant.

[0098] 8) A control method (100) for a diesel engine (1) according to at least one embodiment of the present disclosure includes: A control method (2) for a diesel engine (1) equipped with a turbocharger (3) and a supercharger (4) as superchargers, comprising: a clutch switching step (S101) for switching between an engaged state and a disengaged state of a clutch (16) interposed between a drive shaft (53) of the engine and the supercharger (4); a fuel injection period control step (S102) of controlling the fuel injection period (TQ) based on first association information (231) that associates in advance the engine speed (NA), accelerator opening (AA), and fuel injection period (TQ) to the engine; a fuel injection start timing control step (S103) for controlling a fuel injection start timing (TS) for the engine, The fuel injection start timing control step (S103) a first fuel injection start timing control step of controlling the fuel injection start timing (TS) when the supercharger (4) is in the driving state based on second association information (241) that associates in advance the engine speed (NA), the fuel injection period (TQ), and the fuel injection start timing (TS) when the supercharger (4) is in the driving state; and a second fuel injection start timing control step of controlling the fuel injection start timing (TS) when the supercharger (4) is in the stopped state based on third association information (242) that associates in advance the engine speed (NA), the fuel injection period (TQ), and the fuel injection start timing (TS) when the supercharger (4) is in the stopped state, the third association information (242) being different from the second association information (241).

[0099] According to the method of 8), in the fuel injection start timing control step (S103), the fuel injection start timing (TS) is controlled based on the association information (second association information 241, third association information 242) that differs for each operation state (drive state or stop state) of the supercharger (4), thereby making the fuel injection start timing (TS) appropriate for the operation state of the supercharger (4). In the fuel injection start timing control step (S103), the fuel injection start timing (TS) to the engine is changed, thereby making it possible to change the fuel economy and torque of the engine. In the fuel injection start timing control step (S103), the fuel injection start timing (TS) to the engine is changed so that the fuel economy and torque of the engine after a change in the operation state of the supercharger (4) become the same as the fuel economy and torque of the engine before the change in the operation state of the supercharger (4), thereby making it possible to suppress fluctuations in the fuel economy and torque of the engine that may occur when the operation state of the supercharger (4) changes. By suppressing the fluctuations in the fuel consumption rate and torque of the engine that may occur when the operating state of the supercharger (4) changes, the driver does not need to adjust the accelerator to keep the torque constant. Furthermore, according to the method 8), it is not necessary to change the control of the fuel injection period (TQ) in the fuel injection period control step (S102), so that the control method (100) can be prevented from becoming complicated. [Explanation of symbols]

[0100] 1. Diesel engine 2. Control device 3. Turbocharger 4 Supercharger 5 Engine body 6 Supercharger RPM acquisition device 7 Supercharger pressure ratio acquisition device 11 Intake line 11A First intake flow path 11B Second intake flow path 12 Exhaust line 13 Fuel injection device 14 Fuel supply line 15 Combustion chamber 16 Clutch 17 Gear mechanism 18 Bypass valve 19 Intercooler 21 Database Department 22 Clutch control unit 23 Fuel injection period control unit 24 Fuel injection start timing control unit 25 Bypass valve control section 26 RPM sensor 27 Accelerator sensor 28 Required torque control section 31 Rotating shaft 32 Compressor 33 Turbine 34 impeller 35 Compressor housing 36 Turbine rotor 37 Turbine housing 41 Impeller 42 Housing 43 Rotating shaft 51 cylinders 52 Piston 53 Drive shaft 61 Rotational speed sensor 71 Inlet pressure sensor 72 Outlet pressure sensor 73 Supercharger pressure ratio derivation section 100 Control Method 111 Branch 112 Junction 231 First Association Information 231A Fuel injection period map 241 Secondary Association Information 241A First fuel injection start timing control map 242 Third Association Information 242A Second fuel injection start timing control map 281 Torque Map AA Accelerator opening BL boundary line FER fuel efficiency rate LR Low flow rate operating range NA engine speed NB Supercharger RPM NR normal operation range PR Pressure Ratio S101 Clutch switching step S102 Fuel injection period control step S103 Fuel injection start timing control step S104 Bypass valve control step SP scavenging pressure T elapsed time TA Torque TQ fuel injection period TS Fuel injection start time

Claims

1. A control device for a diesel engine equipped with a turbocharger and a supercharger as a supercharger, a clutch control unit that switches between an engaged and disengaged state of a clutch interposed between a drive shaft of the diesel engine and the supercharger; a fuel injection period control unit that controls the fuel injection period based on first association information that associates in advance a rotation speed of the diesel engine, an accelerator opening, and a fuel injection period into the diesel engine; a fuel injection start timing control unit for controlling a fuel injection start timing for the diesel engine, The control device second association information that associates in advance the rotation speed of the diesel engine, the fuel injection period, and the fuel injection start timing when the supercharger is in a driving state; third association information that associates in advance the rotation speed of the diesel engine, the fuel injection period, and the fuel injection start timing when the supercharger is stopped, the third association information being different from the second association information; The fuel injection start timing control unit When the supercharger is in a driving state, the fuel injection start timing is controlled based on the second association information, and when the supercharger is in a stopped state, the fuel injection start timing is controlled based on the third association information, so that at least one parameter of torque, fuel consumption rate, or scavenging pressure of the diesel engine after the operation state of the supercharger is switched becomes the same as or has a small difference from the parameter of the diesel engine before the operation state is switched. Diesel engine control device.

2. the second association information includes a first fuel injection start timing control map in which the fuel injection start timing is defined depending on the rotation speed of the diesel engine and the fuel injection period, the third association information includes a second fuel injection start timing control map in which the fuel injection start timing is defined depending on the rotation speed of the diesel engine and the fuel injection period; The control device for a diesel engine according to claim 1.

3. The control device is configured to be able to send a signal to the clutch instructing whether the clutch is engaged or disengaged, the fuel injection start timing control unit is configured to determine that an operating state of the supercharger has changed in response to a signal sent from the control device to the clutch. The control device for a diesel engine according to claim 1 or 2.

4. the control device is configured to be capable of transmitting a signal to a bypass valve, which is provided in a bypass flow path that bypasses the supercharger and connects the compressor of the turbocharger and the diesel engine, and is configured to open and close the bypass flow path, instructing the bypass valve to open and close; the fuel injection start timing control unit is configured to determine that an operating state of the supercharger has changed in response to a signal instructed by the control device to the bypass valve. The control device for a diesel engine according to claim 1 or 2.

5. The engine further includes a supercharger rotation speed acquisition device configured to acquire the rotation speed of the supercharger, The fuel injection start timing control unit a determination is made as to whether an operating state of the supercharger has changed in accordance with the rotation speed of the supercharger acquired by the supercharger rotation speed acquisition device; The control device for a diesel engine according to claim 1 or 2.

6. a supercharger pressure ratio acquisition device configured to acquire a pressure ratio of the supercharger; The fuel injection start timing control unit a determination that an operating state of the supercharger has changed is made in accordance with the pressure ratio of the supercharger acquired by the supercharger pressure ratio acquisition device; The control device for a diesel engine according to claim 1 or 2.

7. A diesel engine equipped with the control device according to any one of claims 1 to 6.

8. A control method for a diesel engine equipped with a turbocharger and a supercharger as a supercharger, comprising: a clutch switching step of switching between an engaged state and a disengaged state of a clutch interposed between a drive shaft of the diesel engine and the supercharger; a fuel injection period control step of controlling the fuel injection period based on first association information that associates in advance a rotation speed of the diesel engine, an accelerator opening, and a fuel injection period into the diesel engine; a fuel injection start timing control step of controlling a fuel injection start timing for the diesel engine, The fuel injection start timing control step includes: a first fuel injection start timing control step of controlling the fuel injection start timing when the supercharger is in the driving state based on second association information that associates in advance the number of revolutions of the diesel engine, the fuel injection period, and the fuel injection start timing when the supercharger is in the driving state; a second fuel injection start timing control step of controlling the fuel injection start timing when the supercharger is in the stopped state based on third association information that associates in advance the rotation speed of the diesel engine, the fuel injection period, and the fuel injection start timing when the supercharger is in the stopped state, the third association information being different from the second association information, the fuel injection start timing control step controls the fuel injection start timing to the diesel engine so that at least one parameter of torque, fuel consumption rate, or scavenging pressure of the diesel engine after the operation state of the supercharger is switched is the same as or has a small difference from the parameter of the diesel engine before the operation state is switched. A method for controlling a diesel engine.

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