Engine control device, engine control system, and engine control program

Abstract

To provide an engine control device, an engine control system and an engine control program, which can promptly increase fuel injection amount at appropriate timing while inhibiting an excess air ratio from becoming excessively small.SOLUTION: An engine control device includes: an injection command section for outputting a fuel injection amount command value; a first calculation section for outputting fuel injection amount obtained through FB calculation on the basis of an engine speed deviation to the injection command section as basic fuel injection amount; and a second calculation section for outputting fuel injection amount obtained through FF calculation on the basis of a current engine load of the engine to the injection command section as FF fuel injection amount. When a determination is made that a load input state where the engine load before a prescribed time, which is a prescribed value or smaller, increases by a fluctuation threshold value or larger has occurred, the fuel injection amount command value is switched from the fuel injection amount calculated on the basis of the basic fuel injection amount by the injection command section to fuel injection amount calculated on the basis of a value obtained by adding the FF fuel injection amount to the basic fuel injection amount.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] The engine control device exemplified in Patent Document 1 controls the opening degree of a throttle provided in an engine. More specifically, the engine control device adds the throttle opening degree obtained by a feedforward operation based on the engine load to the throttle opening degree obtained by a feedback operation based on the deviation between the actual rotational speed and the target rotational speed of the engine. The opening degree command value obtained by the addition is sent to a stepping motor that controls the throttle opening degree, and the engine rotational speed is controlled.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the engine load, which has been at a low value, increases to a certain extent, it is necessary to quickly increase the fuel injection amount so as to achieve high responsiveness of engine driving. However, when the engine load is low, since the amount of air supplied to the engine is small, there is a risk that the air excess ratio becomes too small as the fuel injection amount increases. As a result, various problems such as an increase in harmful substances contained in the exhaust gas, a decrease in the thermal efficiency of the engine, or engine stall may occur. Therefore, when the engine load, which has been at a low value, increases, it is necessary to quickly increase the fuel injection amount at an appropriate timing so that the air excess ratio does not become too small.

[0005] An object of the present disclosure is to provide an engine control device, an engine control system, and an engine control program that can quickly increase the fuel injection amount at an appropriate timing while suppressing an excessive decrease in the air-fuel ratio when the engine load, which has been at a low value, increases.

Means for Solving the Problems

[0006] An engine control device according to at least one embodiment of the present disclosure includes an injection command unit for outputting a fuel injection amount command value supplied to the engine, a first calculation unit for outputting, to the injection command unit, as a basic fuel injection amount, a fuel injection amount obtained by feedback calculation based on an engine speed deviation, which is a deviation between the actual engine speed and the target engine speed of the engine, a second calculation unit for outputting, to the injection command unit, as a feedforward fuel injection amount, a fuel injection amount obtained by feedforward calculation based on the current engine load of the engine, a first determination unit for determining whether a load input state has occurred in which the engine load before a specified time, which was below a specified value, has increased by a fluctuation threshold value or more and is configured to switch from a normal control mode in which, when the first determination unit determines that the load input state has occurred, the injection command unit outputs, as the fuel injection amount command value, a first fuel injection amount calculated based on the basic fuel injection amount, to a load input control mode in which the injection command unit outputs, as the fuel injection amount command value, a second fuel injection amount calculated based on a value obtained by adding the feedforward fuel injection amount to the basic fuel injection amount.

[0007] An engine control system according to at least one embodiment of the present disclosure includes the engine, a rotation speed sensor for detecting the rotation speed of the engine, a load sensor for detecting the engine load of the engine The engine control device for acquiring the detection results of the rotation speed sensor and the load sensor respectively, A fuel injection unit provided in the engine for injecting fuel according to the fuel injection amount command value output from the injection command unit of the engine control device is provided.

[0008] The engine control program according to at least one embodiment of the present disclosure is, In an engine device that is a computer, An injection command step for outputting a fuel injection amount command value supplied to the engine; A first calculation step for outputting, as a basic fuel injection amount acquired in the injection command step, the fuel injection amount obtained by feedback calculation based on an engine speed deviation, which is the deviation between the actual engine speed and the target engine speed of the engine; A second calculation step for outputting, as a feedforward fuel injection amount acquired in the injection command step, the fuel injection amount obtained by feedforward calculation based on the current engine load of the engine; A first determination step for determining whether a load input state has occurred in which the engine load before a specified time that was below a specified value has increased by more than a fluctuation threshold value is executed, When it is determined by the first determination step that the load input state has occurred, the engine device is switched from a normal control mode in which a first fuel injection amount calculated based on the basic fuel injection amount in the injection command step is output as the fuel injection amount command value, to a load input control mode in which a second fuel injection amount calculated based on a value obtained by adding the feedforward fuel injection amount to the basic fuel injection amount in the injection command step is output as the fuel injection amount command value.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide an engine control device, an engine control system, and an engine control program that can quickly increase the fuel injection amount at an appropriate timing while suppressing a decrease in the air excess ratio.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0011] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure thereto, but are merely illustrative examples. For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only precisely represent such arrangements, but also represent states of displacement with tolerances or at angles and distances such that the same function can be obtained. For example, expressions indicating that things are in an equal state such as "identical", "equal", and "homogeneous" not only precisely represent an equal state, but also represent states where there are tolerances or differences such that the same function can be obtained. For example, expressions indicating shapes such as a rectangular shape or a cylindrical shape not only represent the shapes of a rectangular shape or a cylindrical shape in a geometrically precise sense, but also represent shapes including uneven portions, chamfered portions, etc. within a range where the same effect can be obtained. On the other hand, the expressions "comprising", "including", or "having" for a component are not exclusive expressions that exclude the existence of other components. Note that the same reference numerals may be given to similar configurations and the description may be omitted.

[0012] <1. Exemplification of the Outline of the Engine Control System 1> FIG. 1 is a conceptual diagram of an engine control system 1 according to an embodiment of the present disclosure. The engine control system 1 of the present embodiment includes an engine 5, an engine control device 20 for controlling the engine 5, a generator 4 connected to the engine 5 via a rotating shaft 19, and a power supply facility 2 for supplying the power generated by the generator 4 to a power supply line 3. The engine 5 is an internal combustion engine such as a diesel engine, for example. The engine control system 1 also includes a boost pressure sensor 14 for detecting the boost pressure of the intake air to the engine 5. The detection result of the boost pressure sensor 14 is sent to the engine control device 20. Further, the engine 5 is provided with a fuel injection unit 9 which may be an injector, for example. In this example, mechanical energy is obtained by the mixing and combustion of the air flowing through the air supply passage 8 and the fuel injected by the fuel injection unit 9, and the rotating shaft 19 rotates. The power generated by the generator 4 operating with the rotation of the rotating shaft 19 is supplied to the power supply line 3 via the power supply facility 2. On the other hand, when a predetermined operation is performed on the power supply facility 2, the generator 4 and the power supply line 3 become separate systems, and the power supply from the generator 4 to the power supply line 3 is cut off.

[0013] The engine control system 1 according to an embodiment further includes a rotational speed sensor 12 for detecting the rotational speed of the engine 5 and a load sensor 11 for detecting the engine load of the engine 5. The rotational speed sensor 12 in this example detects the rotational speed of the rotating shaft 19. The detection result (rpm signal) of the rotational speed sensor 12 is sent to the engine control device 20. Also, the load sensor 11 in this example is a power transducer for measuring the power generated by the generator 4. Since the power generated by the generator 4 increases as the output of the engine 5 increases, the measurement result of the power transducer can be regarded as the engine load. The detection result (KW signal) of the load sensor 11 is sent to the engine control device 20. Note that the load sensor 11 according to other embodiments may be a torque sensor for measuring the torque of the rotating shaft 19.

[0014] The engine control device 20 of the present embodiment controls the fuel injection unit 9 based on the detection results of the load sensor 11, the rotational speed sensor 12, and the boost pressure sensor 14. Further, the fuel injection unit 9 injects fuel according to the injection amount command value sent from the engine control device 20.

[0015] While the generator 4 and the power supply line 3 are on separate systems from each other, the engine load of the engine 5 is, for example, lower than the rated load of the engine 5, and the engine rotational speed, which is the rotational speed of the engine 5, is low. In the following description, the driving of the engine 5 with an engine load below a specified value may be referred to as low-load driving. The specified value is 5% or less of the rated load of the engine 5. Low-load driving is a concept that includes the engine 5 being driven with an engine load that can be substantially regarded as zero.

[0016] While the engine 5 is under low-load driving, since the amount of air supplied to the engine 5 is small, if the fuel injection amount by the fuel injection unit 9 is too large, there is a risk that the air excess ratio will become too small. On the other hand, even while the engine 5 is under low-load driving, for example, when an operation for connecting the generator 4 and the power supply line 3 is started in the power supply facility 2 and the engine load increases to a certain extent, it is desirable for the fuel injection amount to increase rapidly. This is because if the engine 5 can quickly respond to the increase in engine load due to a rapid increase in the fuel injection amount, the power supply amount from the generator 4 to the power supply line 3 will quickly rise.

[0017] In some embodiments of the present disclosure, when the engine load, which has been changing at a low value, increases to a certain extent, the engine control device 20 rapidly increases the fuel injection amount. On the other hand, when the increase amount of the engine load is small, the engine control device 20 does not rapidly increase the fuel injection amount. Therefore, when the engine load increases during low-load driving, the fuel injection amount rapidly increases only at the necessary timing.

[0018] The engine control device 20 is configured by a computer and includes a processor, a memory, and an external communication interface. The processor is a CPU, GPU, MPU, DSP, or a combination thereof. The processor according to other embodiments may be realized by an integrated circuit such as a PLD, ASIC, FPGA, or MCU. The memory is configured to temporarily or non-temporarily store various data and is realized by, for example, at least one of RAM, ROM, or flash memory. According to the program instructions loaded into the memory, the processor appropriately acquires data indicating the detection results of the load sensor 11, the rotational speed sensor 12, and the boost pressure sensor 14, and processes various data.

[0019] <Exemplification of the specific configuration of the engine control device 20> FIG. 2 is a conceptual diagram of the engine control device 20 according to an embodiment of the present disclosure. The engine control device 20 includes an injection command unit 35 for outputting a fuel injection amount command value indicating the fuel injection amount supplied to the engine 5 to the fuel injection unit 9, and a first calculation unit 31 and a second calculation unit 32 for respectively outputting calculation results to the injection command unit 35.

[0020] The first calculation unit 31 is configured to output the fuel injection amount obtained by feedback calculation (hereinafter also referred to as FB calculation) as the basic fuel injection amount to the fuel injection unit 9. The FB calculation in this example is executed based on the engine speed deviation, which is the deviation between the actual engine speed and the target engine speed of the engine 5. The actual engine speed of the engine 5 is, for example, the latest data (current data) indicated by the detection result of the engine speed sensor 12. The first calculation unit 31 obtains the engine speed deviation by subtracting the current actual engine speed from the target engine speed. The FB calculation result by the first calculation unit 31 is reflected in the fuel injection amount command value sent from the injection command unit 35 to the fuel injection unit 9. Then, the rotational speed of the rotating shaft 19 that changes according to the fuel injection amount of the fuel injection unit 9 is detected by the engine speed sensor 12 and returned as an input value to the first calculation unit 31. Thereby, feedback control of the engine speed (hereinafter also referred to as FB control) is realized. Note that the FB control of the present embodiment is PID control, and the FB calculation in the first calculation unit 31 is PID calculation. The FB control according to other embodiments may be P control or PI control.

[0021] Further, the basic fuel injection amount output by the first calculation unit 31 may not be directly output to the injection command unit 35. For example, limit processing may be performed to limit the basic fuel injection amount output from the first calculation unit 31 to be equal to or less than the upper limit fuel injection amount, and the data subjected to the limit processing may be input to the fuel injection unit 9. The upper limit fuel injection amount described above may vary according to the amount of air supplied to the engine 5. For example, the engine control device 20 may change the upper limit fuel injection amount based on the detection results of the engine speed sensor 12 and the boost pressure sensor 14 so that the air excess ratio falls within an appropriate range.

[0022] The second arithmetic unit 32 is configured to output the fuel injection amount obtained by feedforward arithmetic (hereinafter also referred to as FF arithmetic) as the feedforward fuel injection amount to the injection command unit 35. Hereinafter, the feedforward fuel injection amount may be referred to as the FF fuel injection amount. The FF arithmetic in this example is executed based on the current engine load. More specifically, the latest data indicating the detection result of the load sensor 11 is subjected to low-pass filter processing, and the FF fuel injection amount is obtained based on the differential value of the processed data. In this example, further, limit processing for limiting the obtained FF fuel injection amount to a predetermined value or less is performed. The FF fuel injection amount thus obtained is added to the basic fuel injection amount output from the first arithmetic unit 31. By reflecting the fuel injection amount obtained by the addition in the fuel injection amount command value in the injection command unit 35, feedforward control of the engine speed (hereinafter also referred to as FF control) is executed. Note that the fuel injection amount obtained by adding the FF fuel injection amount to the basic fuel injection amount (or the fuel injection amount obtained by adding the FF fuel injection amount to the basic fuel injection amount subjected to the limit processing) may not be directly input to the injection command unit 35. For example, limit processing for limiting the fuel injection amount to an upper limit value or less may be performed, and the processed fuel injection amount may be input to the injection command unit 35. Further, the detection result of the load sensor 11 may not be directly input to the second arithmetic unit 32. For example, data obtained by sequentially performing limit processing and maximum likelihood estimation processing on the detection result may be input to the second arithmetic unit 32.

[0023] The engine control device 20 of the present embodiment is configured to switch between a normal control mode in which only the basic fuel injection amount among the basic fuel injection amount or the FF fuel injection amount is reflected in the fuel injection amount command value, and a load application control mode in which both the basic fuel injection amount and the FF fuel injection amount are reflected in the fuel injection amount command value. When the engine control device 20 is in the normal control mode, the injection command unit 35 outputs the first fuel injection amount calculated based on the basic fuel injection amount as the fuel injection amount command value. When the engine control device 20 is in the load application control mode, the injection command unit 35 outputs the second fuel injection amount calculated based on the value obtained by adding the FF fuel injection amount to the basic fuel injection amount as the fuel injection amount command value. The second fuel injection amount is equal to or greater than the first fuel injection amount. If a large engine load does not occur while the engine 5 is driving at a low load, there is no need to quickly increase the fuel injection amount, and the engine control device 20 is in the normal control mode. On the other hand, when the engine load increases to a certain extent while the engine 5 is driving at a low load, it is necessary to quickly increase the fuel injection amount, so the engine control device 20 switches from the normal control mode to the load application control mode.

[0024] Whether the above switching occurs depends on the determination result of the first determination unit 21, which is a component of the engine control device 20. The first determination unit 21 is configured to determine, for example, based on the detection result of the load sensor 11, whether a load application state has occurred in which the engine load before a specified time, which was below a specified value, has increased by more than a variation threshold value. The detection result of the load sensor 11 input to the first determination unit 21 may be subjected to limit processing and maximum likelihood estimation processing in sequence. The specified time is a time that is sufficiently longer than the time corresponding to the reading frequencies of the load sensor 11 and the rotation speed sensor 12, respectively. The variation threshold value is a constant that is 25% or more of the rated load of the engine 5. The variation threshold value is stored in a memory that constitutes the engine control device 20.

[0025] Examples in which the first determination unit 21 determines that a load application state has occurred and examples in which it does not are illustrated below. FIG. 3 is a conceptual diagram showing the relationship between the temporal change of the engine load and the determination result of the first determination unit 21 according to an embodiment of the present disclosure. All the graphs shown in the figure have the time on the horizontal axis and the engine load indicated by the KW signal on the vertical axis. Also, t c represents the current time, and t b represents the time before the specified time from the current time, and L c represents the specified value of the engine load (the same applies to the graphs shown in FIGS. 6 and 8 described later). Also, T L represents the fluctuation threshold value of the engine load.

[0026] In the example shown by the upper graph in the figure, the engine load at the time t b before the specified time is below the specified value, and the increase amount (ΔL1) of the engine load from before the specified time to the present is equal to or greater than the fluctuation threshold value (T L ). Therefore, the first determination unit 21 determines that a load application state has occurred. This example corresponds to a case where a certain amount of engine load is added during low-load driving of the engine 5. In this case, it is necessary to quickly increase the fuel injection amount and quickly respond to the increase in the engine load. In the example shown by the middle graph in the figure, the time t bThe engine load in [the situation] exceeds the specified value. Therefore, the first determination unit 21 determines that no load input state has occurred. In this example, a case where the engine 5 was not driven at a low load before the specified time corresponds. In this case, an intake air amount and a fuel injection amount supplied to the engine 5 are ensured to a certain extent. Therefore, even if the fuel injection amount is not quickly increased, relatively quick responsiveness of engine driving can be easily realized with respect to an increase in the engine load. Thus, there is little need to quickly increase the fuel injection amount. In the case shown by the lower graph in the figure, the increase amount (ΔL3) of the engine load from before the specified time to the present is below the variation threshold value. Therefore, the first determination unit 21 determines that no load input state has occurred. In this example, a case where the engine load applied to the engine 5 during low-load driving is small corresponds. In this case, if the fuel injection amount is quickly increased, various problems such as an increase in the engine speed with an increase in the fuel injection amount and an unstable operation of the engine 5 may occur. Therefore, it is not preferable to quickly increase the fuel injection amount at such a timing.

[0027] Returning to FIG. 2, an engine control device 20 according to an embodiment includes a feed-forward determination unit (hereinafter referred to as an FF determination unit) 23 configured to receive the determination result of the first determination unit 21 and the FF fuel injection amount of the second calculation unit 32. Only when the determination result of the first determination unit 21 indicates the occurrence of a load input state, the FF determination unit 23 sends the FF fuel injection amount output by the second calculation unit 32 to the injection command unit 35. With this configuration, when the first determination unit 21 determines that a load input state has occurred, the engine control device 20 switches from the normal control mode to the load input control mode, and the fuel injection amount command value switches from the first fuel injection amount to the second fuel injection amount. Note that the FF determination unit 23 may not be provided in the engine control device 20. For example, the calculation result of the second calculation unit 32 may be input to the first determination unit 21, and the function of the FF determination unit 23 may be included in the function of the first determination unit 21.

[0028] According to the above configuration, when the first determination unit 21 determines that a load input state has occurred in which the engine load before the specified time, which was below the specified value, increases by more than the fluctuation threshold value, the engine control device 20 switches to the load input control mode. That is, when the engine load, which has been changing at a low value, increases to a certain extent, the injection amount command value switches from the first fuel injection amount to the second fuel injection amount, so the fuel injection amount increases rapidly. On the other hand, when the engine load before the specified time exceeds the specified value (that is, when there is little need to rapidly increase the fuel injection amount), or when the increase amount of the engine load is less than the fluctuation threshold value, the fuel injection amount command value does not switch to the second fuel injection amount. As a result, a rapid increase in the fuel injection amount at an unnecessary timing and a rapid increase in the fuel injection amount that causes an excessive air excess ratio are suppressed. From the above, an engine control device 20 that can rapidly increase the fuel injection amount at an appropriate timing while suppressing the air excess ratio from becoming too small is realized. Note that the first determination unit 21 according to one embodiment determines the presence or absence of the occurrence of the load input state only based on the change over time of the engine load. The first determination unit 21 according to another embodiment does not determine that the load input state has occurred unless other parameters such as the engine speed also satisfy the specified conditions (details will be described later). In any of the embodiments, the above advantages can be obtained.

[0029] The first calculation unit 31 according to one embodiment is configured to maintain the feedback gain value in the FB calculation without changing it under the load input control mode. In an embodiment where the first calculation unit 31 performs PID calculation, the PID gain value is maintained. The PID gain value may be the same value in both the normal control mode and the load input control mode. According to the above configuration, since the setting change of the first calculation unit 31 associated with the switch from the normal control mode to the load input control mode is suppressed, the calculation process by the first calculation unit 31 is simplified, and a rapid increase in the fuel injection amount at an unnecessary timing can be further suppressed.

[0030] The switching from the load input control mode to the normal control mode will be described. In the embodiment illustrated in FIG. 2, the switching occurs based on the determination result of the second determination unit 22 which is a component of the engine control device 20. The second determination unit 22 is configured to determine whether at least one of a first condition that the basic fuel injection amount becomes equal to or greater than the upper limit fuel injection amount determined from a characteristic value correlated with the intake air amount of the air supplied to the engine 5, or a second condition that the engine speed becomes equal to or greater than a specified speed is satisfied.

[0031] The first condition will be described. The second determination unit 22 determines the upper limit fuel injection amount based on the detection results of the rotation speed sensor 12 and the boost pressure sensor 14. It is understood that the detection result of the boost pressure sensor 14 is a characteristic value having a high correlation with the actual intake air amount. If the basic fuel injection amount obtained by the FB calculation of the first calculation unit 31 is equal to or greater than the upper limit fuel injection amount, the fuel injection amount supplied to the engine 5 is sufficiently high, and from the viewpoint of suppressing the decrease in the air excess ratio of the engine 5, there is little need to continue the control for quickly increasing the fuel injection amount. By including the first condition in the determination condition of the second determination unit 22, an increase in the fuel injection amount at such a timing can be suppressed.

[0032] The second condition will be described. The second determination unit 22 determines whether the actual engine speed specified by the detection result of the rotation speed sensor 12 becomes equal to or greater than the specified speed. If the actual engine speed is equal to or greater than the specified speed, the engine 5 is rotating at a certain speed and the output of the engine 5 is also at a certain level or higher even without increasing the actual fuel injection amount to the upper limit fuel injection amount. Therefore, there is little need to continue the control for quickly increasing the fuel injection amount. By including the second condition in the determination condition of the second determination unit 22, a rapid increase in the fuel injection amount at such a timing can be suppressed.

[0033] As described above, when the basic fuel injection amount output by the first calculation unit 31 is equal to or greater than the upper limit fuel injection amount, the actual fuel injection amount is sufficiently high, and there is little need for the injection amount command value to be the second fuel injection amount from the perspective of suppressing an excessive decrease in the air excess ratio of the engine 5. Further, when the actual engine speed becomes equal to or higher than the specified speed without the basic fuel injection amount reaching the upper limit fuel injection amount, the engine 5 can rotate at a certain speed without making the actual fuel injection amount sufficiently high, so there is little need for the injection amount command value to be the second fuel injection amount. In this regard, according to the above configuration, when at least one of the conditions is satisfied, the engine control device 20 switches from the load input control mode to the normal control mode, and the fuel injection amount command value switches from the second fuel injection amount to the first fuel injection amount. Therefore, it is possible to further suppress a sudden increase in the fuel injection amount at an unnecessary timing. Note that the determination process of the second determination unit 22 may be executed when the first determination unit 21 determines that a load input state has occurred, or may be executed regardless of the determination result of the first determination unit 21. In the latter embodiment, the determination result of the second determination unit 22 is referred to after the first determination unit 21 determines that a load input state has occurred. In any of the embodiments, the above advantages can be obtained.

[0034] <3. Exemplification of the Configuration of the First Determination Unit 21> FIG. 4 is a conceptual diagram showing the configuration of a first determination unit 21 according to an embodiment of the present disclosure. The first determination unit 21 includes a low load determination unit 26 for determining whether the engine load before a specified time is equal to or less than a specified value, and a load increase determination unit 27 for determining whether an increase amount of the engine load is equal to or greater than a variation threshold value. The determination processes of the low load determination unit 26 and the load increase determination unit 27 may be executed in parallel, or the determination process of the low load determination unit 26 may be executed before or after the determination process of the load increase determination unit 27. Hereinafter, the determination conditions of the low load determination unit 26 and the load increase determination unit 27 will be described.

[0035] FIG. 5 is a conceptual diagram showing the determination conditions of the low load determination unit 26 according to an embodiment of the present disclosure. The low load determination unit 26 according to an embodiment is configured to determine that the engine load before a specified time is equal to or less than a specified value when both of the conditions N1 and N2 are satisfied. The condition N1 is a condition that the engine load before the specified time is equal to or less than the specified value. The engine load before the specified time is obtained based on the detection result of the load sensor 11. The condition N2 is a condition that the actual engine speed is equal to or less than a second engine speed threshold value. The actual engine speed is obtained based on the detection result of the engine speed sensor 12. The actual engine speed referred to in this determination is any one of the current actual engine speed, the actual engine speed before the specified time, or the actual engine speed at any time from before the specified time to the present. The advantage of determining the satisfaction of not only the condition N1 but also the condition N2 in the determination of whether the engine load before the specified time is equal to or less than the specified value will be described below.

[0036] FIG. 6 is a graph conceptually showing the change over time of the engine load according to an embodiment of the present disclosure. This graph shows a case where the engine load indicated by the KW signal suddenly drops due to a factor that the engine 5 was not driving at a low load. Examples of the factor that suddenly occurs include, for example, intermittent misfire of the engine 5 or noise that affects the measurement of the load sensor 11. When intermittent misfire occurs, the suddenly dropped engine load immediately recovers to the original level, and when noise occurs, the actual engine load does not fall below the specified value. In these cases, although it is not necessary for the engine control device 20 to switch to the load input control mode and the fuel injection amount to suddenly increase, the engine load before the specified time indicated by the KW signal becomes equal to or less than the specified value. On the other hand, even when the sudden factors exemplified above occur, the actual engine speed tends to maintain a high state. In this regard, according to the above configuration, if the actual engine speed becomes equal to or less than the second engine speed threshold value and the condition N2 is not satisfied, the low load determination unit 26 does not determine that the engine load before the specified time is equal to or less than the specified value. Therefore, it is possible to suppress the sudden increase in the fuel injection amount at an unnecessary timing.

[0037] FIG. 7A is a conceptual diagram showing the determination conditions of the load increase determination unit 27 according to an embodiment. The load increase determination unit 27 according to an embodiment is configured to determine that the increase amount of the engine load is equal to or greater than the fluctuation threshold value when all at least one load increase condition is satisfied. The load increase conditions in this example include load increase conditions A1, A2, and A3. Hereinafter, when collectively referring to individual determination conditions such as the load increase conditions A1, A2, and A3, they may simply be referred to as load increase conditions. The load increase condition A1 is a condition that the first load deviation, which is the deviation between the engine load at a prescribed time before the current engine load, is equal to or greater than the fluctuation threshold value. The first load deviation is obtained by subtracting the engine load indicated by the detection result of the load sensor 11 at a prescribed time before from the engine load indicated by the detection result of the current load sensor 11. The load increase condition A2 is a condition that the engine speed deviation is equal to or less than the first speed threshold value. The method for obtaining the engine speed deviation is as described above. The load increase condition A3 is a condition that the second load deviation, which is the deviation between the current engine load and the processed engine load obtained by applying a low-pass filter process to the engine load at a prescribed time before, is equal to or greater than the fluctuation threshold value. The second load deviation is obtained by subtracting the processed engine load from the current engine load.

[0038] According to the configuration in which the load increase condition A1 is included in the load increase conditions of the load increase determination unit 27 shown in FIG. 7A, the first load deviation as the deviation of the engine load is used to determine whether the increase amount of the engine load is equal to or greater than the fluctuation threshold value. Thereby, the determination accuracy by the load increase determination unit 27 can be ensured. Note that the above advantage can be obtained regardless of whether the load increase condition includes at least one of the load increase condition A2 or the load increase condition A3 in addition to the load increase condition A1. When the load increase condition includes only the load increase condition A1, when all one load increase condition A1 is satisfied, it is determined that the increase amount of the engine load is equal to or greater than the fluctuation threshold value.

[0039] In addition, the load increase condition includes a load increase condition A2 in addition to the load increase condition A1. That is, the load increase determination unit 27 is configured to determine that the amount of increase in the engine load is equal to or greater than the fluctuation threshold when the first load deviation is equal to or greater than the fluctuation threshold and the engine speed deviation is equal to or less than the first speed threshold. As described above, the engine load indicated by the KW signal sent to the load increase determination unit 27 may temporarily drop suddenly due to a factor that occurs suddenly. In this case, although the fuel injection amount does not actually need to increase rapidly, the first load deviation becomes equal to or greater than the fluctuation threshold. On the other hand, the engine speed deviation tends to remain high even when the sudden factor occurs. In this regard, according to the above configuration, if the engine speed deviation does not become equal to or less than the first speed threshold as the actual engine load increases by more than the fluctuation threshold, it is not determined that the amount of increase in the engine load is equal to or greater than the fluctuation threshold. Therefore, it is possible to further suppress the rapid increase in the fuel injection amount at unnecessary timing. Note that the above advantages can be obtained regardless of whether the load increase condition includes a condition A3 in addition to the load increase conditions A1 and A2.

[0040] In addition, the load increase condition includes a load increase condition A3 in addition to the load increase condition A1. That is, the load increase determination unit 27 is configured to determine that the amount of increase in the engine load is equal to or greater than the variation threshold when the first load deviation is equal to or greater than the variation threshold and the second load deviation is equal to or greater than the variation threshold. As described above, the engine load indicated by the KW signal sent to the load increase determination unit 27 may temporarily drop sharply due to sudden factors. In this regard, according to the above configuration, since low-pass filter processing is performed on the engine load before the specified time sent to the injection command unit 35, the temporary sharp drop phenomenon is not reflected in the engine load acquired by the load increase determination unit 27. Thereby, it is possible to suppress the second load deviation from becoming equal to or greater than the variation threshold due to sudden factors, and further suppress the sudden increase in the fuel injection amount at unnecessary timing. In addition, since the determination thresholds of the first load deviation and the second load deviation are both the same variation threshold, the determination process by the load increase determination unit 27 can be simplified. Note that the above advantages can be obtained regardless of whether the load increase condition includes a load increase condition A2 in addition to the load increase conditions A1 and A3. Also, the determination threshold of the second load deviation may be a value different from the above variation threshold.

[0041] FIG. 7B is a conceptual diagram showing the determination conditions of the load increase determination unit 27 according to another embodiment. The load increase condition according to another embodiment includes a load increase condition B1 instead of the load increase condition A1. And in the embodiment illustrated in the figure, when all of the above-described load increase conditions A2 and A3 are satisfied in addition to the load increase condition B1, the load increase determination unit 27 is configured to determine that the amount of increase in the engine load is equal to or greater than the variation threshold. And the load increase condition B1 is a condition in which the differential value of the current engine load is equal to or greater than the differential threshold. The load increase determination unit 27 acquires the differential value of the current engine load based on the deviation between the current engine load and the engine load at the time retrogressed from the current time by the time corresponding to the reading frequency of the load sensor 11. The load increase determination unit 27 determines whether the load increase condition B1 is satisfied by comparing the acquired differential value with the differential threshold as a specified value stored in the memory.

[0042] In an embodiment in which the load increase condition B1 is included in the load increase condition, the load increase determination unit 27 is configured to determine that the increase amount of the engine load is equal to or greater than the fluctuation threshold when the differential value of the current engine load is equal to or greater than the differential threshold. The advantages of this configuration will be described below.

[0043] FIG. 8 is another graph showing the change over time of the engine load according to an embodiment of the present disclosure. This graph shows a case where the engine load gradually increases while the engine 5 is operating at a low load. In this case, although it is almost certain that the engine load will reach or exceed the specified value in the future, since the arrival time is late, the timing at which the engine control device 20 switches from the normal control mode to the load input control mode is delayed (in the example of FIG. 8, the time at which the switch is made to the load input control mode is t c later than t d ). In this regard, according to the above configuration, even when the rate of increase of the engine load is slow, if the differential value of the engine load becomes equal to or greater than the differential threshold, it is determined that the increase amount of the engine load is equal to or greater than the threshold. As a result, even when the rate of increase of the engine load is slow, the engine control device 20 can quickly switch to the load input control mode and rapidly increase the fuel injection amount. Note that the load increase condition may include only the load increase condition B1, or may include the load increase condition A1 in addition to the load increase conditions B1, A2, and A3. The above advantages can be obtained in any of the embodiments.

[0044] <4. Exemplification of the arithmetic processing of the first arithmetic unit 31> The engine control device 20 (see FIG. 2) according to one embodiment may switch the parameter to be FB-controlled between the normal control mode and the load application control mode. Specifically, in the normal control mode, the first calculation unit 31 outputs, as the basic fuel injection amount, the fuel injection amount obtained by FB calculation based on the engine speed deviation. On the other hand, in the load application control mode, the fuel injection amount obtained by FB calculation based on the deviation between the actual engine load and the target engine load of the engine 5 is output as the basic fuel injection amount (not shown). The actual engine load is acquired based on the detection result of the load sensor 11. The target engine load is stored, for example, as a fixed value in the memory constituting the engine control device 20. According to the above configuration, as the switching from the normal control mode to the load application control mode occurs, the engine load is directly controlled by the first calculation unit 31. Thereby, during the occurrence of the load application state, the engine load can be controlled more finely.

[0045] In addition, in other embodiments, regardless of whether the engine control device 20 is in the normal control mode or the load application control mode, the engine speed may be the target of FB control.

[0046] <5. Exemplification of the calculation process of the second calculation unit 32> The FF fuel injection amount of the second calculation unit 32 according to another embodiment may be determined based on the correspondence data associating the engine load and the fuel injection amount. The correspondence data according to this embodiment is data that is also referred to while the engine 5 is being driven under the rated engine load. The correspondence data may be a data table associating the engine load and the fuel injection amount, or may be a prescribed functional formula. According to the above configuration, there is no need to prepare dedicated data for obtaining the FF fuel injection amount. Therefore, while simplifying the calculation process by the second calculation unit 32, it is possible to suppress a sudden increase in the fuel injection amount at an unnecessary timing.

[0047] <6. Load fluctuation response process> FIG. 9 is a flowchart showing the load fluctuation response process according to an embodiment of the present disclosure. When the engine 5 starts low-load driving, the load fluctuation response process is executed by at least one processor (hereinafter also simply referred to as a processor) mounted on the engine control device 20. In the following description, steps may be abbreviated as "S". Also, at the start of the load fluctuation response process, it is assumed that the engine control device 20 is in the normal control mode.

[0048] First, the processor determines whether a load application state has occurred in the engine 5 (S11). The details of this determination process are as described above, and S11 executed by the processor includes the determination process executed by the above-described first determination unit 21.

[0049] If it is determined that the load application state has not occurred (S11: NO), the processor executes FB control that treats the fuel injection amount obtained by the above-described FB calculation as the basic fuel injection amount (S13). S13 executed by the processor includes the calculation process executed by the first calculation unit 31. Note that when S13 is executed, the fuel injection amount obtained by the FF calculation based on the current engine load is not added to the basic fuel injection amount. At this time, the FF calculation may be executed or may be stopped. In S13, the engine control device 20 is in the normal control mode.

[0050] The processor acquires the basic fuel injection amount output in S13 and outputs the first fuel injection amount calculated based on the basic fuel injection amount as an injection amount command value to the fuel injection unit 9 (S15). In S15, the basic fuel injection amount may be treated as the first fuel injection amount, or data obtained by subjecting the basic fuel injection amount to low-pass filter processing may be treated as the first fuel injection amount. S15 executed by the processor includes the output process executed by the injection command unit 35 in the normal control mode.

[0051] Next, the processor determines whether to end the load fluctuation response process (S17). For example, when an engine stop instruction for the engine control device 20 is input as data (S17: YES), the processor ends the process. When it is determined not to end the load fluctuation response process (S17: NO), the processor returns the process to S11. While the situation where no load application state occurs continues, the processor repeats S11 to S15 in order, and the engine control device 20 is maintained in the normal control mode.

[0052] When it is determined that a load application state has occurred (S11: YES), the processor switches the signal acquired to execute the FB calculation from the engine speed deviation to the first load deviation (S19). In one embodiment, the engine control device 20 switches from the normal control mode to the load application control mode at this time.

[0053] Subsequently, in addition to the FB control, the processor executes FF control that reflects the FF fuel injection amount obtained by the above-described FF calculation in the fuel injection amount command value (S21). In S21, the basic fuel injection amount obtained by the FB calculation and the FF fuel injection amount obtained by the FF calculation are input to and output from the fuel injection unit 9. S21 executed by the processor includes arithmetic processes executed by the first arithmetic unit 31 and the second arithmetic unit 32, respectively.

[0054] The processor outputs the second fuel injection amount calculated based on the fuel injection amount output in S21 (the value obtained by adding the FF fuel injection amount to the basic fuel injection amount) to the fuel injection unit 9 as the injection amount command value (S23). In S23, the total value of the basic fuel injection amount and the FF fuel injection amount may be treated as the second fuel injection amount, or data obtained by subjecting the total value to low-pass filter processing may be treated as the second fuel injection amount. S23 executed by the processor includes output processing executed by the injection command unit 35 in the load application control mode.

[0055] The processor determines whether the load application state has disappeared (S25). The details of this determination process are as described above, and S25 executed by the processor includes the determination process executed by the second determination unit 22. If it is determined that the load application state has disappeared (S25: YES), the processor shifts the process to S13, and the engine control device 20 switches from the load application control mode to the normal control mode. Then, the parameter to be controlled by the FB control also switches from the engine load to the engine speed. On the other hand, if it is determined that the load application state has not disappeared (S25: NO), the processor shifts the process to S17. While the situation where the load application state occurs continues, the processor repeatedly executes S11, S19 to S25, and S17 in order. At this time, in S19, if the parameter to be controlled by the FB control has switched to the engine load deviation, a skip process in which no special control is executed is executed.

[0056] In addition, in other embodiments, S19 may not be executed. In this case, when it is determined that the load application state has occurred (S11: YES), the engine control device 20 switches from the normal control mode to the load application control mode by executing S21.

[0057] <7. Others> In another embodiment, the engine 5 according to the other embodiment may be connected to a prime mover mounted on the vehicle instead of being connected to the generator 4. In this case, the load sensor 11 may be a torque sensor for measuring the output torque of the engine 5. Also in such an embodiment, for example, the idling operation of the vehicle corresponds to the low-load driving of the engine 5, and it is preferable that the fuel injection amount increases quickly at an appropriate timing so that the air excess ratio does not become too small.

[0058] <8. Summary> Several embodiments described above are understood as follows, for example.

[0059] 1) The engine control device (20) according to an embodiment of the present disclosure An injection command unit (35) for outputting a fuel injection amount command value indicating the fuel injection amount supplied to the engine (5); A first calculation unit (31) for outputting, as a basic fuel injection amount, the fuel injection amount obtained by feedback calculation based on the engine speed deviation, which is the deviation between the actual engine speed and the target engine speed of the engine, to the injection command unit; A second calculation unit (32) for outputting, as a feedforward fuel injection amount, the fuel injection amount obtained by feedforward calculation based on the current engine load of the engine to the injection command unit; A first determination unit (21) for determining whether a load input state has occurred in which the engine load before a specified time, which was below a specified value, has increased by more than a variation threshold; and comprising When it is determined by the first determination unit that the load input state has occurred, the injection command unit switches from a normal control mode in which the injection command unit outputs, as the fuel injection amount command value, a first fuel injection amount calculated based on the basic fuel injection amount, to a load input control mode in which the injection command unit outputs, as the fuel injection amount command value, a second fuel injection amount calculated based on a value obtained by adding the feedforward fuel injection amount to the basic fuel injection amount.

[0060] According to the configuration of 1) above, when a load input state occurs in which the engine load before the specified time, which was below the specified value, increases by more than the fluctuation threshold value, the engine control device switches to the load input control mode. That is, when the engine load, which has been transitioning at a low value, rises to a certain extent, the fuel injection amount command value switches from the first fuel injection amount to the second fuel injection amount, and the fuel injection amount increases rapidly. On the other hand, when the engine load before the specified time exceeds the specified value (that is, when there is little need to rapidly increase the fuel injection amount), or when the increase amount of the engine load is less than the fluctuation threshold value, the fuel injection amount command value does not switch to the second fuel injection amount. As a result, a rapid increase in the fuel injection amount at an unnecessary timing and a rapid increase in the fuel injection amount at a timing where the air excess ratio may become too small are suppressed. From the above, an engine control device is realized that can rapidly increase the fuel injection amount at an appropriate timing while suppressing the air excess ratio from becoming too small.

[0061] 2) In some embodiments, it is the engine control device described in 1) above, a second determination unit (22) for determining whether at least one of the conditions that the basic fuel injection amount is equal to or greater than the upper limit fuel injection amount determined from a characteristic value correlated with the air supply amount of the air supplied to the engine, or that the actual engine speed is equal to or greater than the specified speed is satisfied, when it is determined by the second determination unit that at least one of the conditions is satisfied under the load input control mode, it is configured to switch from the load input control mode to the normal control mode.

[0062] When the basic fuel injection amount output by the first calculation unit is equal to or greater than the upper limit fuel injection amount, the actual fuel injection amount is sufficiently high, and there is little need for the fuel injection amount command value to become the second fuel injection amount from the perspective of suppressing an excessive decrease in the air excess ratio of the engine. Further, when the rotational speed of the actual engine reaches or exceeds the specified rotational speed without the basic fuel injection amount reaching the upper limit fuel injection amount, the engine can be driven at a certain rotational speed without making the actual fuel injection amount sufficiently high, so there is little need for the fuel injection amount command value to become the second fuel injection amount. In this regard, according to the configuration of 2) above, when at least one of the conditions is satisfied, the engine control device switches from the load input control mode to the normal control mode, and the fuel injection amount command value switches from the second fuel injection amount to the first fuel injection amount. Therefore, it is possible to suppress a sudden increase in the fuel injection amount at an unnecessary timing.

[0063] 3) In some embodiments, the engine control device according to 1) or 2) above, The first calculation unit is configured to maintain a feedback gain value in the feedback calculation in the load input control mode.

[0064] According to the configuration of 3) above, since a change in the setting of the first calculation unit associated with the switching from the normal control mode to the load input control mode is suppressed, while simplifying the calculation process by the first calculation unit, it is possible to further suppress a sudden increase in the fuel injection amount at an unnecessary timing.

[0065] 4) In some embodiments, the engine control device according to any one of 1) to 3) above, The first determination unit, A low load determination unit (26) for determining whether the engine load before the specified time is equal to or less than the specified value, and A load increase determination unit (27) for determining whether an increase amount of the engine load is equal to or greater than the fluctuation threshold value Including, The load increase determination unit is configured to determine that the increase amount of the engine load is equal to or greater than the fluctuation threshold value when all of at least one load increase condition is satisfied. The load increase condition includes a first load increase condition (load increase condition A1) in which a first load deviation, which is a deviation between the current engine load and the engine load before the specified time and greater than the current engine load, is equal to or greater than the fluctuation threshold value.

[0066] According to the configuration of 4) above, since the first load deviation as the deviation of the engine load is used to determine whether the increase amount of the engine load is equal to or greater than the fluctuation threshold value, the determination accuracy by the load increase determination unit can be ensured.

[0067] 5) In some embodiments, the engine control device according to any one of 1) to 4) above, The first determination unit, A low load determination unit (26) for determining whether the engine load before the specified time is equal to or less than the specified value, A load increase determination unit (27) for determining whether the increase amount of the engine load is equal to or greater than the fluctuation threshold value Including, The load increase determination unit is configured to determine that the increase amount of the engine load is equal to or greater than the fluctuation threshold value when all of at least one load increase condition is satisfied. The load increase condition includes a second load increase condition (load increase condition B1) in which the differential value of the current engine load is equal to or greater than the differential threshold value.

[0068] According to the configuration of 5) above, even when the increase rate of the engine load is slow, if the differential value of the engine load is equal to or greater than the differential threshold value, it is determined that the increase amount of the engine load is equal to or greater than the threshold value. Thereby, even when the increase rate of the engine load is slow and the time until the engine load reaches the specified value or more is long, the engine control device can quickly respond and rapidly increase the fuel injection amount.

[0069] 6) In some embodiments, the engine control device according to 4) or 5) above, The load increase condition includes a third load increase condition (load increase condition A3) in which a second load deviation, which is a deviation between the current engine load and a processed engine load obtained by subjecting the engine load before the specified time to low-pass filter processing, is equal to or greater than the fluctuation threshold value.

[0070] The engine load indicated by the signal sent to the load increase determination unit may temporarily drop suddenly due to factors such as intermittent misfires or noise in the engine. In this regard, according to the configuration of 6) above, when the first load deviation is equal to or greater than the fluctuation threshold value, and when the second load deviation, which is a deviation between the current engine load and the processed engine load obtained by subjecting the engine load before the specified time to low-pass filter processing, is equal to or greater than the fluctuation threshold value, it is determined that the increase amount of the engine load is equal to or greater than the fluctuation threshold value. Since low-pass filter processing is performed on the engine load before the specified time, the temporary sudden drop phenomenon is not reflected in the engine load acquired by the load increase determination unit. Thereby, it is possible to further suppress a sudden increase in the fuel injection amount at an unnecessary timing. Also, since the determination threshold values of both the first load deviation and the second load deviation are the fluctuation threshold values, the determination process by the load increase determination unit can be simplified.

[0071] 7) In some embodiments, it is the engine control device according to any one of 4) to 6) above, The load increase condition includes a fourth load increase condition (load increase condition A2) in which the engine speed deviation is equal to or less than a first speed threshold value.

[0072] The engine load indicated by the signal sent to the load increase determination unit may temporarily drop sharply due to factors such as intermittent misfires or noises in the engine that occur suddenly. In this case, although the fuel injection amount does not actually need to increase rapidly, the first load deviation becomes equal to or greater than the fluctuation threshold value. On the other hand, even when the above-mentioned sudden factors occur, the engine speed deviation tends to remain high. In this regard, according to the configuration of the above (7), when the first load deviation is equal to or greater than the fluctuation threshold value and the engine speed deviation is equal to or less than the first engine speed threshold value, the load increase determination unit determines that the increase amount of the engine load is equal to or greater than the fluctuation threshold value. Therefore, if the engine speed deviation does not become equal to or less than the first engine speed threshold value as the actual engine load increases by an amount equal to or greater than the fluctuation threshold value, it is not determined that the increase amount of the engine load is equal to or greater than the fluctuation threshold value. Thus, it is possible to further suppress the rapid increase in the fuel injection amount at unnecessary timings.

[0073] 8) In some embodiments, the engine control device according to any one of the above (4) to (7), The low load determination unit is configured to determine that the engine load before the specified time is equal to or less than the specified value when the engine load before the specified time is equal to or less than the specified value and the actual engine speed is equal to or less than the second engine speed threshold value.

[0074] The engine load indicated by the signal sent to the low load determination unit may temporarily drop sharply due to factors such as intermittent misfires or noises in the engine that occur suddenly. In this case, although the fuel injection amount does not actually need to increase rapidly, the engine load before the specified time becomes equal to or less than the specified value. On the other hand, even when the above-mentioned sudden factors occur, the actual engine speed tends to remain high. In this regard, according to the above configuration, if the actual engine speed does not become equal to or less than the second engine speed threshold value, it is not determined that the engine load before the specified time is equal to or less than the specified value. Thus, it is possible to further suppress the rapid increase in the fuel injection amount at unnecessary timings.

[0075] 9) In some embodiments, the engine control device according to any one of the above (1) to (8), The second arithmetic unit is configured to output, as the feedforward fuel injection amount, a fuel injection amount obtained based on correspondence data associating the engine load and the fuel injection amount, which is data referred to at the rated engine load of the engine, and the current engine load.

[0076] According to the configuration of 9) above, there is no need to prepare dedicated data for obtaining the feedforward fuel injection amount. Therefore, while simplifying the arithmetic processing by the second arithmetic unit, it is possible to further suppress a sudden increase in the fuel injection amount at unnecessary timings.

[0077] 10) In some embodiments, there is provided an engine control device according to any one of 1) to 9) above, wherein the first arithmetic unit, in the normal control mode, outputs, as the basic fuel injection amount, a fuel injection amount obtained by the feedback arithmetic based on the engine speed deviation, and in the load input control mode, is configured to output, as the basic fuel injection amount, a fuel injection amount obtained by the feedback arithmetic based on the deviation between the actual engine load and the target engine load of the engine.

[0078] According to the configuration of 10) above, with the switching from the normal control mode to the load input control mode, the engine load comes to be directly controlled by the first arithmetic unit. Thereby, during the occurrence of the load input state, the engine load can be controlled more finely.

[0079] 11) An engine control system (1) according to at least one embodiment of the present disclosure includes the engine, a rotation speed sensor (12) for detecting the rotation speed of the engine, a load sensor (11) for detecting the engine load of the engine, and an engine control device (20) according to any one of 1) to 10) above for acquiring detection results of the rotation speed sensor and the load sensor respectively. A fuel injection unit (9) provided in the engine for injecting fuel according to the fuel injection amount command value output from the injection command unit of the engine control device is provided.

[0080] According to the configuration of the above (11), for the same reason as above (1), an engine control system can be realized that can quickly increase the fuel injection amount at an appropriate timing while suppressing an excessive decrease in the air-fuel ratio.

[0081] 12) The engine control program according to at least one embodiment of the present disclosure causes an engine device (20) that is a computer to an injection command step (S15, S23) for outputting a fuel injection amount command value that is the fuel injection amount supplied to the engine (5); a first calculation step (S13) for outputting, as the basic fuel injection amount obtained in the injection command step, the fuel injection amount obtained by feedback calculation based on the engine speed deviation that is the deviation between the actual engine speed and the target engine speed of the engine; a second calculation step (S23) for outputting, as the feedforward fuel injection amount obtained in the injection command step, the fuel injection amount obtained by feedforward calculation based on the current engine load of the engine; a first determination step (S11) for determining whether a load input state has occurred in which the engine load before a specified time that was below a specified value has increased by more than a variation threshold value is executed, When it is determined by the first determination step that the load input state has occurred, the engine device is switched from a normal control mode in which a first fuel injection amount calculated based on the basic fuel injection amount in the injection command step is output as the fuel injection amount command value to a load input control mode in which a second fuel injection amount calculated based on a value obtained by adding the feedforward fuel injection amount to the basic fuel injection amount in the injection command step is output as the fuel injection amount command value (S19 or S21).

[0082] According to the configuration of the above (12), for the same reason as the above (1), it is possible to quickly increase the fuel injection amount at an appropriate timing while suppressing the air excess ratio from becoming too small.

Explanation of Signs

[0083] 1: Engine control system 5: Engine 9: Fuel injection unit 11: Load sensor 12: Rotation speed sensor 20: Engine control device 21: First determination unit 22: Second determination unit 26: Low load determination unit 27: Load increase determination unit 31: First calculation unit 32: Second calculation unit 35: Injection command unit A1, A2, A3, B1: Load increase conditions

Claims

1. An injection command unit for outputting a fuel injection amount command value indicating the fuel injection amount supplied to the engine; A first calculation unit for outputting, as a basic fuel injection amount, the fuel injection amount obtained by feedback calculation based on the engine speed deviation, which is the deviation between the actual engine speed and the target engine speed of the engine, to the injection command unit; A second calculation unit for outputting, as a feedforward fuel injection amount, the fuel injection amount obtained by feedforward calculation based on the current engine load of the engine, to the injection command unit; A first determination unit for determining whether a load input state has occurred in which the engine load before a specified time is less than or equal to a specified value and increases by more than a fluctuation threshold; Comprising; When the first determination unit determines that the load input state has occurred, from the normal control mode in which the injection command unit outputs, as the fuel injection amount command value, a first fuel injection amount calculated based on the basic fuel injection amount, to a load input control mode in which the injection command unit outputs, as the fuel injection amount command value, a second fuel injection amount calculated based on a value obtained by adding the feedforward fuel injection amount to the basic fuel injection amount. It is configured to switch. Engine control device.

2. Further comprising a second determination unit for determining whether at least one of the conditions that the basic fuel injection amount becomes equal to or greater than the upper limit fuel injection amount determined from the characteristic value correlated with the air supply amount of the air supplied to the engine, or the condition that the actual engine speed becomes equal to or greater than the specified speed is satisfied. When it is determined by the second determination unit that at least one of the conditions is satisfied under the load input control mode, it is configured to switch from the load input control mode to the normal control mode. The engine control device according to claim 1.

3. The first calculation unit is configured to maintain the feedback gain value in the feedback calculation under the load input control mode. The engine control device according to claim 1 or 2.

4. The first determination unit is A low load determination unit for determining whether the engine load before the specified time is less than or equal to the specified value; A load increase determination unit for determining whether the increase amount of the engine load is greater than or equal to the fluctuation threshold; Including, The load increase determination unit is configured to determine that the increase amount of the engine load is greater than or equal to the fluctuation threshold when all of at least one load increase condition is satisfied. ​ The load increase condition includes a first load increase condition in which a first load deviation, which is a deviation between the current engine load and the engine load before the specified time and which is greater than or equal to the fluctuation threshold value, is satisfied. The engine control device according to any one of claims 1 to 3.

5. The first determination unit includes a low load determination unit for determining whether the engine load before the specified time is less than or equal to the specified value, and a load increase determination unit for determining whether an increase amount of the engine load is greater than or equal to the fluctuation threshold value, and the load increase determination unit is configured to determine that the increase amount of the engine load is greater than or equal to the fluctuation threshold value when all of at least one load increase condition is satisfied. The load increase condition includes a second load increase condition in which a differential value of the current engine load is greater than or equal to a differential threshold value. The engine control device according to any one of claims 1 to 4.

6. The load increase condition includes a third load increase condition in which a second load deviation, which is a deviation between the current engine load and a processed engine load obtained by performing low-pass filter processing on the engine load before the specified time, is greater than or equal to the fluctuation threshold value. The engine control device according to claim 4 or 5.

7. The load increase condition includes a fourth load increase condition in which the engine speed deviation is less than or equal to a first speed threshold value. The engine control device according to any one of claims 4 to 6.

8. The low load determination unit is configured to determine that the engine load before the specified time is less than or equal to the specified value when the engine load before the specified time is less than or equal to the specified value and the actual engine speed is less than or equal to a second speed threshold value. The engine control device according to any one of claims 4 to 7.

9. The second calculation unit is configured to output, as the feedforward fuel injection amount, a fuel injection amount obtained based on the correspondence data associating the engine load and the fuel injection amount, which is data referred to at the rated engine load of the engine, and the current engine load. The engine control device according to any one of claims 1 to 8.

10. The first calculation unit outputs, under the normal control mode, the fuel injection amount obtained by the feedback calculation based on the engine speed deviation as the basic fuel injection amount. configured to output, as the basic fuel injection amount, the fuel injection amount obtained by the feedback operation based on the deviation between the actual engine load and the target engine load of the engine under the load input control mode The engine control device according to any one of claims 1 to 9.

11. the engine, a rotational speed sensor for detecting the rotational speed of the engine, a load sensor for detecting the engine load of the engine, and the engine control device according to any one of claims 1 to 10 for acquiring the detection results of the rotational speed sensor and the load sensor respectively; a fuel injection unit provided in the engine for injecting fuel according to the fuel injection amount command value output from the injection command unit of the engine control device; An engine control system comprising:

12. In an engine device that is a computer, an injection command step for outputting a fuel injection amount command value supplied to the engine; a first calculation step for outputting, as the basic fuel injection amount obtained in the injection command step, the fuel injection amount obtained by a feedback operation based on the engine speed deviation, which is the deviation between the actual engine speed and the target engine speed of the engine; a second calculation step for outputting, as the feedforward fuel injection amount obtained in the injection command step, the fuel injection amount obtained by a feedforward operation based on the current engine load of the engine; a first determination step for determining whether a load input state has occurred in which the engine load before a specified time that is less than or equal to a specified value increases by more than a fluctuation threshold; to execute, When it is determined by the first determination step that the load input state has occurred, the engine device is switched from the normal control mode in which the first fuel injection amount calculated based on the basic fuel injection amount in the injection command step is output as the fuel injection amount command value to the load input control mode in which the second fuel injection amount calculated based on the value obtained by adding the feedforward fuel injection amount to the basic fuel injection amount in the injection command step is output as the fuel injection amount command value. An engine control program.

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