Engine system and method for controlling the engine system

Abstract

To appropriately monitor fuel injection amount by using a simple configuration while suppressing cost and a development period.SOLUTION: An engine system includes: an injector for injecting fuel to a cylinder of an engine body; an engine rotational speed sensor for detecting actual rotational speed of the engine body; and a control device for controlling the injector. The control device calculates fuel injection amount for control through feedback control that uses a difference between target rotational speed of the engine body and the rotational speed detected by the engine rotational speed sensor (Step S111 to Step S116), controls the injector so as to inject the calculated injection amount for control (Step S125), calculates injection amount for monitoring by using a predetermined method different from the feedback control (Step S121), calculates an injection amount difference between the injection amount for control and the injection amount for monitoring (Step S122), and executes predetermined processing corresponding to the injection amount difference (Step S124).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This disclosure relates to an engine system and a method for controlling an engine system, and more particularly, to an engine system and a method for controlling an engine system suitable for controlling an injector.

Background Art

[0002] Conventionally, there has been a device for monitoring whether the control of the fuel injection amount of a diesel engine is being performed normally (see, for example, Patent Document 1). The required fuel injection amount is calculated using the engine speed and the accelerator operation amount. When such a diesel engine is used in an industrial system or general-purpose machinery, isochronous control is used. Isochronous control is a control that changes the injection amount so as to follow a target rotational speed when the rotational speed fluctuates due to the load on the output shaft of the diesel engine.

[0003] In the first monitoring of Patent Document 1, the same engine speed and accelerator operation amount as those used for calculating the required injection amount are used to calculate the injection amount for monitoring. Then, by comparing the calculated injection amount for monitoring and the required injection amount, it is monitored whether the required injection amount is normal.

[0004] Also, in the second monitoring of Patent Document 1, the injection period of the injector that injects the calculated injection amount is measured, and the actual injection amount is calculated from the measured injection period. Then, by comparing the calculated actual injection amount and the required injection amount, it is monitored whether the required injection amount is normal.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the first monitoring of Patent Document 1, it is conceivable to calculate the injection amount for monitoring using an ECU (Electronic Control Unit) different from the ECU that calculates the required injection amount. However, in this case, problems such as an increase in cost and development period occur. In addition, since the cooperative control between the two ECUs is constructed both hardware-wise and software-wise, the system becomes complicated and the possibility of abnormalities increases.

[0007] Also, in the second monitoring of Patent Document 1, even if the required injection amount calculated by the ECU is abnormal, if injection is performed by the injector according to the required injection amount, the injection control is determined to be normal. Also, in isochronous control, the feedback amount is greatly reflected in the load on the output shaft of the engine, and it was difficult to estimate the injection amount for monitoring using the engine speed and the accelerator operation amount.

[0008] This disclosure has been made to solve the above-described problems, and its object is to provide an engine system and a control method for an engine system that can appropriately monitor the fuel injection amount with a simple configuration while suppressing cost and development period.

Means for Solving the Problems

[0009] The engine system according to this disclosure includes an injector that injects fuel into the cylinders of the engine, a sensor that detects the actual rotational speed of the engine, and a control unit that controls the injector. The control unit calculates the control injection amount of fuel by feedback control using the difference between the target rotational speed of the engine and the actual rotational speed detected by the sensor, controls the injector to inject the calculated control injection amount, calculates the monitoring injection amount by a predetermined method different from the feedback control, calculates the injection amount difference between the control injection amount and the monitoring injection amount, and executes a predetermined process according to the injection amount difference.

[0010] Preferably, the predetermined method is a method of calculating the monitoring injection amount using a map in which the relationship between the rotational speed difference obtained by subtracting the target rotational speed from the actual rotational speed and the monitoring injection amount for each actual rotational speed is determined in advance.

[0011] More preferably, in the map, the monitoring injection amount in the region where the rotational speed difference is a negative value is the allowable injection amount at each actual rotational speed.

[0012] Also preferably, in the map, the monitoring injection amount in the region where the rotational speed difference is a positive value is determined in advance reflecting the decrease in the injection amount due to the rotational speed difference.

[0013] According to another aspect of this disclosure, in a control method of an engine system, the engine system includes an injector that injects fuel into a cylinder of the engine, a sensor that detects the actual rotational speed of the engine, and a control unit that controls the injector. The control method includes steps in which the control unit calculates a control injection amount of fuel by feedback control using the difference between the target rotational speed of the engine and the actual rotational speed detected by the sensor, controls the injector to inject the calculated control injection amount, calculates a monitoring injection amount by a predetermined method different from the feedback control, calculates an injection amount difference between the control injection amount and the monitoring injection amount, and executes a predetermined process according to the injection amount difference.

Advantages of the Invention

[0014] According to this disclosure, in order to control the injector, it is only necessary to provide one control unit, so the cost and development period can be suppressed and a simple configuration can be achieved. Further, since the monitoring injection amount is calculated by a predetermined method different from the feedback control in the calculation of the control injection amount, the control injection amount can be properly monitored. As a result, it is possible to provide an engine system and a control method of the engine system that can properly monitor the fuel injection amount with a simple configuration while suppressing the cost and development period.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0017] FIG. 1 is a diagram showing the schematic configuration of an engine system 1 equipped with a supercharger according to this embodiment. In this embodiment, the engine system 1 will be described by taking, for example, a system including a common rail type diesel engine as an example, but a system including other types of engines (for example, gasoline engines, etc.) may also be used. Further, the engine system 1 is used to drive industrial systems such as compressors or hydraulic pumps or devices such as general-purpose machines, but is not limited thereto, and may be used to drive other machines such as vehicles.

[0018] The engine system 1 includes an engine body 10, an air cleaner 20, an intercooler 26, an intake manifold 28, a supercharger 30, an exhaust manifold 50, an exhaust treatment device 55, an exhaust gas recirculation device (hereinafter referred to as an EGR (Exhaust Gas Recirculation) device) 60, an engine rotational speed sensor 102, an air flow meter 104, a supercharging pressure sensor 106, an outside air temperature sensor 108, an atmospheric pressure sensor 110, and a control device 200.

[0019] The engine body 10 includes a cylinder 12 and an injector 16. The engine body 10 may be an in-line engine, or may be an engine with other cylinder layouts (for example, V-type or horizontal type).

[0020] The injector 16 is a fuel injection device provided at the top of the cylinder 12 and connected to a common rail (not shown). The fuel stored in a fuel tank (not shown) is pressurized to a predetermined pressure by a supply pump (not shown) and supplied to the common rail. The fuel supplied to the common rail is injected from the injector 16 at a predetermined timing. The injector 16 supplies the fuel injection amount Qv commanded according to the control signal from the control device 200 into the cylinder 12.

[0021] The air cleaner 20 removes foreign matters from the air inhaled from the outside of the engine body 10. One end of the first intake pipe 22 is connected to the air cleaner 20.

[0022] The other end of the first intake pipe 22 is connected to the intake air inlet of the compressor 32 of the supercharger 30. One end of the second intake pipe 24 is connected to the intake air outlet of the compressor 32. The compressor 32 supercharges the air flowing from the first intake pipe 22 and supplies it to the second intake pipe 24.

[0023] One end of the intercooler 26 is connected to the other end of the second intake pipe 24. The intercooler 26 is an air-cooled or water-cooled heat exchanger that cools the air flowing through the second intake pipe 24.

[0024] One end of the third intake pipe 27 is connected to the other end of the intercooler 26. The other end of the third intake pipe 27 is connected to the intake manifold 28. The intake manifold 28 is connected to the intake port of the cylinder 12 of the engine body 10. A diesel throttle 25 is provided in the middle of the third intake pipe 27, on the intercooler 26 side from the branch point with the EGR 60 described later. The diesel throttle 25 adjusts the intake air flow rate according to the control signal from the control device 200.

[0025] The exhaust manifold 50 is connected to the exhaust port of the cylinder 12 of the engine body 10. One end of the first exhaust pipe 52 is connected to the exhaust manifold 50. The other end of the first exhaust pipe 52 is connected to the exhaust inlet of the turbine 36 of the supercharger 30. Therefore, the exhaust discharged from the exhaust port of each cylinder is supplied to the turbine 36 via the exhaust manifold 50 and the first exhaust pipe 52.

[0026] One end of the second exhaust pipe 54 is connected to the exhaust outlet of the turbine 36. An exhaust treatment device 55 including an oxidation catalyst 56, a PM (Particulate Matter) removal filter 57, and an SCR (Selective Catalytic Reduction) catalyst 58 and a muffler or the like are connected to the other end of the second exhaust pipe 54. Therefore, the exhaust discharged from the exhaust outlet of the turbine 36 is discharged to the outside of the vehicle via the second exhaust pipe 54, the exhaust treatment device 55, and the muffler or the like.

[0027] The third intake pipe 27 (or the intake manifold 28) and the first exhaust pipe 52 (or the exhaust manifold 50) are connected by an EGR device 60 without passing through the cylinder 12 of the engine body 10. The EGR device 60 includes an EGR valve 62, an EGR passage 66, and an EGR cooler 63. The EGR passage 66 connects the third intake pipe 27 and the first exhaust pipe 52 (or the exhaust manifold 50). The EGR valve 62 and the EGR cooler 63 are provided in the middle of the EGR passage 66. The EGR cooler 63 is an air-cooled or water-cooled heat exchanger that cools the EGR gas flowing to the intake side via the EGR passage 66.

[0028] The EGR valve 62 is a regulating valve that adjusts the flow rate of the EGR gas flowing through the EGR passage 66 in response to a control signal from the control device 200. The exhaust in the exhaust manifold 50 is returned to the intake side as EGR gas via the EGR device 60, thereby reducing the combustion temperature in the cylinder 12 and reducing the generation amount of NOx.

[0029] The supercharger 30 includes a compressor 32, a turbine 36, a variable nozzle mechanism 40, and an actuator 44. A compressor wheel 34 is housed in the housing of the compressor 32, and a turbine wheel 38 is housed in the housing of the turbine 36. The compressor wheel 34 and the turbine wheel 38 are connected by a connecting shaft 42 and rotate integrally. Therefore, the compressor wheel 34 is rotationally driven by the energy of the exhaust gas supplied to the turbine wheel 38.

[0030] The variable nozzle mechanism 40 is disposed in the surrounding exhaust gas inlet portion centered on the rotation axis of the turbine wheel 38, and includes a plurality of vanes (see FIG. 2) that guide the exhaust gas supplied from the first exhaust pipe 52 to the turbine wheel 38, and a link mechanism that changes the gap between adjacent vanes (hereinafter, the size of this gap is also referred to as "VN (vane nozzle) opening") by rotating each of the plurality of vanes. The actuator 44 changes the VN opening of the variable nozzle mechanism 40 by operating the link mechanism in response to an operation instruction from the control device 200.

[0031] By changing the VN opening of the variable nozzle mechanism 40, the flow path of the exhaust gas in the exhaust gas inlet portion to the turbine wheel 38 is narrowed or expanded. Thereby, the flow velocity of the exhaust gas blown onto the turbine wheel 38 can be changed.

[0032] The operation of the engine system 1 is controlled by the control device 200. The control device 200 includes a CPU (Central Processing Unit) that performs various processes, a memory including a ROM (Read Only Memory) that stores programs and data, and a RAM (Random Access Memory) that stores the processing results of the CPU, etc., and an input / output port (not shown in any figure) for communicating information with the outside. Sensors such as those described above (for example, engine speed sensor 102, air flow meter 104, supercharging pressure sensor 106, outside air temperature sensor 108, and atmospheric pressure sensor 110, etc.) are connected to the input port. Devices to be controlled (for example, injector 16, actuator 44, and EGR valve 62, etc.) are connected to the output port.

[0033] Based on the signals from each sensor and device, as well as the maps and programs stored in the memory, the control device 200 controls various devices so that the engine system 1 reaches a desired operating state. Note that various controls are not limited to software processing, and can also be processed by dedicated hardware (electronic circuits). In addition, the control device 200 incorporates a timer circuit (not shown) for measuring time.

[0034] The engine speed sensor 102 detects the rotational speed of the crankshaft, which is the output shaft of the engine body 10, as the engine speed NE. The engine speed sensor 102 transmits a signal indicating the detected engine speed NE to the control device 200.

[0035] The air flow meter 104 detects the flow rate of fresh air (intake air amount) Qin introduced into the first intake pipe 22. The air flow meter 104 transmits a signal indicating the detected intake air amount Qin to the control device 200.

[0036] The supercharging pressure sensor 106 detects the pressure in the intake manifold 28 as the supercharging pressure. The supercharging pressure sensor 106 transmits a signal indicating the detected supercharging pressure to the control device 200.

[0037] The outside air temperature sensor 108 detects the temperature of the outside air of the vehicle on which the engine system 1 is mounted. The outside air temperature sensor 108 transmits a signal indicating the detected outside air temperature to the control device 200.

[0038] The atmospheric pressure sensor 110 detects the pressure of the outside air of the vehicle on which the engine system 1 is mounted, that is, the atmospheric pressure. The atmospheric pressure sensor 110 transmits a signal indicating the detected atmospheric pressure to the control device 200.

[0039] The operation unit 105 receives an operation by the user and transmits a signal indicating the content of the received operation to the control device 200. The operation unit 105 is provided outside the housing of the device on which the engine system 1 is mounted. The operation unit 105 is, for example, a multi-stage switching dial, but is not limited thereto, and may be another type of operation unit.

[0040] FIG. 2 is a block diagram relating to the control of the fuel injection amount in this embodiment. Referring to FIG. 2, the control of the fuel injection amount is performed by the control device 200. That is, each block in FIG. 2 is configured in the control device 200. In this embodiment, each block in FIG. 2 is virtually configured in the control device 200 by executing the software processing shown in the flowchart of FIG. 3 described later. However, any one of the blocks in FIG. 2 may be configured as a hardware circuit in the control device 200.

[0041] In the control of the injection amount, first, in block 211, an instruction of the rotational speed of the engine body 10 is acquired. The instruction of the rotational speed is acquired, for example, from the operation unit 105. For example, when the operation unit 105 is a multi-stage switching dial, a value indicating the stage switched by the switching dial is acquired as the instruction of the rotational speed.

[0042] In block 212, the target rotational speed of the engine body 10 indicated by the instruction of the rotational speed acquired in block 211 is specified. For example, when the operation unit 105 is a switching dial with a plurality of steps, among the rotational speeds predetermined for each step, the rotational speed corresponding to the step indicated by the value acquired in block 211 is specified as the target rotational speed.

[0043] In block 213, a predetermined basic injection amount map indicating the correspondence between the target rotational speed and the basic injection amount is used to specify the basic injection amount corresponding to the target rotational speed specified in block 212.

[0044] In block 214, the control injection amount is calculated by adding the feedback amount calculated in block 216, which will be described later, to the basic injection amount specified in block 213.

[0045] The control device 200 outputs a control signal for injecting the control injection amount calculated in block 214 to the injector 16. When receiving the control signal, the injector 16 operates to inject the control injection amount indicated by the control signal into the cylinder 12. As a result, a driving force is output by the rotation of the crankshaft of the engine body 10.

[0046] In block 215, the actual rotational speed NE of the engine body 10 is specified by receiving a signal indicating the rotational speed NE of the crankshaft of the engine body 10 from the engine rotational speed sensor 102.

[0047] In block 216, a predetermined calculation formula for calculating the feedback amount is used based on the rotational speed difference obtained by subtracting the target rotational speed specified in block 212 from the rotational speed NE specified in block 215, and the feedback amount is calculated.

[0048] In such a configuration, it is conceivable to monitor whether the control of the fuel injection amount is being performed normally. As a first monitoring method, it is conceivable to calculate a monitoring injection amount in the same manner as the method described above. By comparing this monitoring injection amount with the control injection amount calculated in block 214, it is monitored whether the control injection amount is normal.

[0049] As a second monitoring method, it is conceivable to measure the injection period of injector 16 that injects the control injection amount, and calculate the actual injection amount from the measured injection period. By comparing this actual injection amount with the control injection amount, it is monitored whether the control injection amount is normal.

[0050] In the first monitoring, in order to enhance the effectiveness of the monitoring, it is conceivable to calculate the monitoring injection amount using a control device different from the control device 200. However, in such a case, problems such as an increase in cost and development period occur. Also, since the cooperative control between the two control devices is constructed both hardware-wise and software-wise, the system becomes complex and the possibility of anomalies occurring increases.

[0051] Also, in the second monitoring, even if the control injection amount calculated by the control device 200 is abnormal, if the injector 16 injects according to the control injection amount, the injection control will be judged to be normal.

[0052] Therefore, the control device 200 calculates the control injection amount of the fuel by feedback control using the difference between the target rotational speed of the engine body 10 and the rotational speed NE detected by the engine rotational speed sensor 102, controls the injector 16 to inject the calculated control injection amount, calculates the monitoring injection amount by a predetermined method different from the feedback control, calculates the injection amount difference between the control injection amount and the monitoring injection amount, and executes a predetermined process according to the injection amount difference.

[0053] Accordingly, in order to control the injector 16, it is only necessary to provide one control device 200, so that the cost and development period can be reduced and a simple configuration can be achieved. Further, since the monitoring injection amount is calculated by a predetermined method different from the feedback control in the calculation of the control injection amount, the control injection amount can be properly monitored. As a result, it is possible to properly monitor the fuel injection amount with a simple configuration while suppressing the cost and development period.

[0054] Referring again to FIG. 2, in block 221, the monitoring injection amount map is specified using the target rotational speed specified in block 212 and the rotational speed NE specified in block 215. As shown in FIG. 4 described later, the monitoring injection amount map is a map showing the relationship between the difference between the target rotational speed and the rotational speed NE and the monitoring injection amount.

[0055] In block 222, the monitoring injection amount is specified using the monitoring injection amount map specified in block 221. Then, the control injection amount calculated in block 214 and the monitoring injection amount specified in block 222 are compared, and processing according to the comparison result is executed. Thereby, the control injection amount is monitored by the monitoring injection amount.

[0056] As shown in FIG. 2, the monitoring injection amount in the block group 220 including blocks 221 and 222 is calculated in a manner different from the calculation of the control injection amount by the feedback control in the block group 210 including blocks 213, 214, and 216.

[0057] FIG. 3 is a flowchart showing the flow of the rotational speed control process in this embodiment. This rotational speed control process is called and executed by the control device 200 from the upper process at each predetermined control cycle. Referring to FIG. 3, the control device 200 acquires, as an instruction of the rotational speed of the engine body 10, a value indicating the stage switched by the operation unit 105 as described in block 211 of FIG. 2 (step S111).

[0058] As described in block 212 of FIG. 2, the control device 200 specifies the target rotational speed of the engine body 10 indicated by the instruction of the rotational speed acquired in step S111 (step S112).

[0059] As described in block 213 of FIG. 2, the control device 200 uses a predetermined basic injection amount map showing the correspondence between the target rotational speed and the basic injection amount to specify the basic injection amount corresponding to the target rotational speed specified in step S112 (step S113).

[0060] As described in blocks 215 and 216 of FIG. 2, the control device 200 uses a predetermined calculation formula for calculating the feedback amount to calculate a feedback amount corresponding to the rotational speed difference obtained by subtracting the target rotational speed specified in step S112 from the actual rotational speed NE of the engine body 10 indicated by the signal received from the engine rotational speed sensor 102 (step S115).

[0061] As described in block 214 of FIG. 2, the control device 200 calculates the control injection amount by adding the feedback amount calculated in step S115 to the basic injection amount specified in step S113 (step S116).

[0062] As described in blocks 221 and 222 of FIG. 2, the control device 200 specifies a monitoring injection amount map using the target rotational speed specified in step S112 and the actual rotational speed NE of the engine body 10 indicated by the signal received from the engine rotational speed sensor 102, and calculates the monitoring injection amount using the specified monitoring injection amount map (step S121).

[0063] FIG. 4 is a diagram for explaining a monitoring injection amount map in this embodiment. Referring to FIG. 4, the horizontal axis represents the rotational speed difference between the rotational speed NE of the engine body 10 and the target rotational speed. The vertical axis represents the monitoring injection amount. In the region where the rotational speed difference is negative, since the target rotational speed is greater than the actual rotational speed NE, it is controlled to the acceleration side by feedback control. In the region where the rotational speed difference is positive, since the actual rotational speed NE is greater than the target rotational speed, it is controlled to the deceleration side by feedback control.

[0064] As shown in FIG. 4, in the monitoring injection amount map, for each rotational speed NE, the relationship between the rotational speed difference and the monitoring injection amount is defined. If the control injection amount is smaller than the line indicating this relationship, it is determined to be normal, and if the control injection amount is larger than the line indicating this relationship, it is determined to be abnormal.

[0065] For example, in the relationship of rotational speed NE = 1200 (rpm), in the region from the region where the rotational speed difference is negative to +50 (rpm) (region A in FIG. 4), the safe maximum injection amount (allowable injection amount) at rotational speed NE = 1200 (rpm) is taken as the monitoring injection amount. Also, in the region from +50 (rpm) to +150 (rpm) (region B in FIG. 4), the control injection amount is the sum of the basic injection amount at rotational speed NE = 1200 (rmp) and the upper limit injection amount of the feedback amount. Since the feedback amount decreases as the rotational speed difference increases, the upper limit injection amount of the feedback amount is predetermined to reflect this decrease in the injection amount.

[0066] Returning to FIG. 3, the control device 200 subtracts the monitoring injection amount calculated in step S121 from the control injection amount calculated in step S116 to calculate an injection amount difference (step S122).

[0067] The control device 200 determines whether or not the injection amount difference calculated in step S122 exceeds a predetermined value (step S123). Here, it is determined whether or not the injection amount difference exceeds a predetermined value, but it may be determined whether or not it is equal to or greater than the predetermined value. The predetermined value is a reference value determined in advance as a criterion for determining that it is abnormal when the injection amount difference exceeds (or is equal to or greater than) this predetermined value, and is a value of 0 or more.

[0068] When it is determined that the injection amount difference exceeds the predetermined value (YES in step S123), the control device 200 executes a process of controlling the injector 16 so as to stop the control of fuel injection as a predetermined process according to the injection amount difference (step S124). As a result, fuel is no longer injected into the cylinder 12 of the engine body 10, so the rotational operation of the engine body 10 stops.

[0069] On the other hand, when it is determined that the injection amount difference does not exceed the predetermined value (NO in step S123), the control device 200 controls the injector 16 to inject the control injection amount calculated in step S116 (step S125). After step S124 or step S125, the control device 200 returns the process to be executed to the process at a higher level than the call source of this rotational speed control process.

[0070] [Modification Example] (1) In the above-described embodiment, as shown in FIGS. 2 and 3, the instruction of the rotational speed is obtained from the operation unit 105 of the device in which the engine system 1 is mounted. However, the present invention is not limited to this, and when the engine system 1 is mounted on a vehicle, the instruction of the rotational speed may be obtained as the operation amount of the accelerator pedal. Further, the instructed rotational speed may be changed steplessly, may be switched between two steps of low (opening corresponding to the idling rotational speed) and high (opening corresponding to a predetermined rotational speed higher than the idling rotational speed), or may be switched between a plurality of steps.

[0071] (2) In the above-described embodiment, as shown in step S124 of FIG. 3, as a predetermined process according to the injection amount difference between the control injection amount and the monitoring injection amount, a process of stopping the fuel injection by the injector 16 was executed. However, the present invention is not limited to this, and the predetermined process according to the injection amount difference may be any other process as long as it is a process for eliminating the injection amount difference or a process for prompting the user to eliminate the injection amount difference. The predetermined process may be, for example, a process of closing an intake shutter such as the diesel throttle 25, or a process of notifying the user of a warning to prompt the stop of the engine body 10.

[0072] (3) In the above-described embodiment, as shown in FIG. 1, the engine system 1 is configured to include the supercharger 30 and the EGR device 60. However, the present invention is not limited to this, and the engine system 1 may be configured not to include at least one of the supercharger 30 and the EGR device 60.

[0073] (4) The above-described disclosure can be regarded as a disclosure of the engine body 10 or the engine system 1, can be regarded as a disclosure of the control device 200 of the engine body 10 or the engine system 1, can be regarded as a disclosure of an industrial system or a general-purpose machine equipped with the engine system 1, can be regarded as a disclosure of other machines such as a vehicle equipped with the engine system 1, and can be regarded as a disclosure of a control method by the control device 200 of the engine body 10 or the engine system 1 or a control program executed by the control device 200.

[0074] [Summary] (1) As shown in FIG. 1, the engine system 1 includes an injector 16 that injects fuel into the cylinder 12 of the engine body 10, an engine speed sensor 102 that detects the actual rotational speed NE of the engine body 10, and a control device 200 that controls the injector 16. As shown in FIGS. 2 to 4, the control device 200 calculates the control injection amount of fuel by feedback control using the difference between the target rotational speed of the engine body 10 and the rotational speed NE detected by the engine speed sensor 102 (for example, from block 211 to block 216 in FIG. 2, from step S111 to step S116 in FIG. 3), controls the injector 16 to inject the calculated control injection amount (for example, step S125 in FIG. 3), calculates the monitoring injection amount by a predetermined method different from the feedback control (for example, block 221 and block 222 in FIG. 2, step S121 in FIG. 3), calculates the injection amount difference between the control injection amount and the monitoring injection amount (for example, step S122 in FIG. 3), and executes a predetermined process according to the injection amount difference (for example, step S124 in FIG. 3).

[0075] Accordingly, in order to control the injector 16, it is only necessary to provide one control device 200, so that the cost and development period can be suppressed and a simple configuration can be achieved. Further, since the monitoring injection amount is calculated by a predetermined method different from the feedback control in the calculation of the control injection amount, the control injection amount can be properly monitored. As a result, the injection amount of fuel can be properly monitored with a simple configuration while suppressing the cost and development period.

[0076] (2) As shown in FIGS. 2 to 4, the predetermined method is a method of calculating the monitoring injection amount using a monitoring injection amount map (for example, see FIG. 4) in which the relationship between the rotational speed difference obtained by subtracting the target rotational speed from the actual rotational speed NE and the monitoring injection amount for each actual rotational speed NE is determined in advance. Thereby, the monitoring injection amount can be calculated by a simple method. As a result, the injection amount of fuel can be properly monitored with a simpler configuration while suppressing the cost and development period.

[0077] (3) As shown in FIG. 4, in the monitoring injection amount map, the monitoring injection amount in the region where the rotational speed difference is a negative value is the allowable injection amount at each rotational speed NE. Thereby, when the target rotational speed is greater than the actual rotational speed NE of the engine body 10, it is possible to prevent the control injection amount from exceeding the monitoring injection amount which is the allowable injection amount.

[0078] (4) As shown in FIG. 4, in the monitoring injection amount map, the monitoring injection amount in the region where the rotational speed difference is a positive value is determined in advance reflecting the decrease in the injection amount due to the rotational speed difference. Thereby, when the actual rotational speed NE of the engine body 10 is greater than the target rotational speed, it is possible to prevent the control injection amount from exceeding the monitoring injection amount determined reflecting the decrease in the injection amount due to the rotational speed difference.

[0079] Each of the embodiments disclosed this time is also planned to be implemented in appropriate combination. And it should be considered that all the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the description of the above embodiments but by the claims, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0080] 1 Engine system, 10 Engine block, 12 Cylinders, 16 Injector, 20 Air cleaner, 22 First intake pipe, 24 Second intake pipe, 25 Diesel throttle, 26 Intercooler, 27 Third intake pipe, 28 Intake manifold, 30 Supercharger, 32 Compressor, 34 Compressor wheel, 36 Turbine, 38 Turbine wheel, 40 Variable nozzle mechanism, 42 Connecting shaft, 44 Actuator, 50 Exhaust manifold, 52 First exhaust pipe, 54 Second exhaust pipe, 55 Exhaust treatment device, 56 Oxidation catalyst, 57 PM removal filter, 58 SCR catalyst, 60 EGR device, 62 EGR valve, 63 EGR cooler, 66 EGR passage, 102 Engine speed sensor, 104 Airflow meter, 105 Operation unit, 106 Supercharging pressure sensor, 108 Ambient temperature sensor, 110 Atmospheric pressure sensor, 200 Control device.

Claims

1. An injector that injects fuel into a cylinder of an engine, a sensor that detects an actual rotational speed of the engine, and a control unit that controls the injector, wherein the control unit calculates a control injection amount of fuel by feedback control using a difference between a target rotational speed of the engine and the actual rotational speed detected by the sensor, controls the injector to inject the calculated control injection amount, calculates a monitoring injection amount by a predetermined method different from the feedback control, calculates an injection amount difference between the control injection amount and the monitoring injection amount by subtracting the monitoring injection amount from the control injection amount, and when the injection amount difference is equal to or greater than a predetermined value, as a predetermined process according to the injection amount difference, executes a process of controlling the injector to stop fuel injection, an engine system.

2. The predetermined method is a method of calculating the monitoring injection amount using a map in which a relationship for each actual rotational speed between a rotational speed difference obtained by subtracting the target rotational speed from the actual rotational speed and the monitoring injection amount is determined in advance, the engine system according to claim 1.

3. In the map, the monitoring injection amount in a region where the rotational speed difference is a negative value is an allowable injection amount at each actual rotational speed, the engine system according to claim 2.

4. In the map, the monitoring injection amount in a region where the rotational speed difference is a positive value is predetermined in reflection of a decrease in the injection amount due to the rotational speed difference, the engine system according to claim 2.

5. A control method for an engine system, wherein the engine system includes an injector that injects fuel into a cylinder of an engine, a sensor that detects an actual rotational speed of the engine, and a control unit that controls the injector, and the control method includes steps in which the control unit calculates a control injection amount of fuel by feedback control using a difference between a target rotational speed of the engine and the actual rotational speed detected by the sensor, controls the injector to inject the calculated control injection amount, calculates a monitoring injection amount by a predetermined method different from the feedback control, and calculates an injection amount difference between the control injection amount and the monitoring injection amount by subtracting the monitoring injection amount from the control injection amount If the injection amount difference is equal to or greater than a predetermined value, the control method of the engine system includes a step of executing a process of controlling the injector so as to stop the control of fuel injection as a predetermined process according to the injection amount difference.

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