JP2018178785A - Diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize fuel injection where torque from an engine never exceeds an upper limit, in a Diesel engine with an EGR device.SOLUTION: An EGR device 60 is configured to connect an exhaust passage with a suction passage not via an engine body 10, to reflux part of exhaust gas to the suction passage. An ECU 200 is configured to control an injector 16 so that a fuel injection amount never exceeds a torque limit injection amount indicating an upper limit of a fuel injection amount determined based on an upper limit of torque occurring in the engine body 10. Then, the ECU 200 is configured to, based on reduction of an EGR ratio in the EGR device 60, reduce the torque limit injection amount so that torque never exceeds the upper limit due to the reduction of the EGR ratio.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a diesel engine, and more particularly to fuel injection control of a diesel engine provided with an EGR (Exhaust Gas Recirculation) device.

  Unexamined-Japanese-Patent No. 6-299894 (patent document 1) discloses the diesel engine provided with an EGR apparatus. In this diesel engine, when the atmospheric pressure is equal to or less than a predetermined pressure, the amount of EGR gas (the amount of exhaust gas recirculated to the intake side by the EGR device) is corrected to decrease. As a result, the amount of fresh air intake is secured against the reduction in output due to the reduction in the amount of intake air, and the reduction in output is prevented (see Patent Document 1).

JP-A-6-299894

  The torque generated by the engine can be increased by increasing the fuel injection amount, but in order to prevent the generation of the excessive torque, the upper limit of the fuel injection amount so that the torque does not exceed the upper limit (torque limit injection amount ) May be provided.

  On the other hand, in recent years, the demand for reduction of exhaust emissions has been increasing, and it may be necessary to operate the EGR device up to the full load of the engine. Therefore, it is necessary to design the full load performance with the EGR device operated, and to design the torque limit injection amount with the EGR device operated accordingly.

  Here, the EGR rate (the ratio of the amount of EGR gas occupied in the intake gas) may be reduced (including a cut) depending on the operating environment (the high and low of the outside air temperature, etc.) and other fail safe. For example, if the intake air is at a high temperature because the intake air is at a high temperature, the exhaust gas will also be at a high temperature, so that the EGR rate is reduced to protect the valve provided in the passage of the EGR device. It can be done. Alternatively, when the intake air is at a low temperature due to the low temperature of the intake air, it is possible to lower the EGR rate to prevent the corrosion due to the condensation of the intake gas containing the exhaust gas component.

  When the EGR rate is reduced, the combustion efficiency is improved. Therefore, even if the fuel injection amount is constant, the torque generated by the engine is increased. Therefore, the torque generated by the engine may exceed the upper limit. Such a problem is not particularly studied in Patent Document 1 above.

  The present disclosure has been made to solve such a problem, and an object thereof is to realize, in a diesel engine equipped with an EGR device, fuel injection in which the torque generated by the engine does not exceed the upper limit.

  The diesel engine of the present disclosure includes an engine body having a combustion chamber, an EGR device, a fuel injection device, and a control device. The EGR device is configured to connect the exhaust passage to the intake passage without passing through the engine body, and to recirculate part of the exhaust gas to the intake passage. The fuel injector is configured to inject fuel into the combustion chamber. The control device controls the fuel injection device such that the fuel injection amount does not exceed the torque limit injection amount indicating the upper limit of the fuel injection amount determined according to the upper limit of the torque generated by the engine body. Then, the control device reduces the torque limit injection amount as the EGR rate decreases so that the torque does not exceed the upper limit as the EGR rate decreases by the EGR device.

  The control device may estimate the EGR rate using the amount of intake gas sucked into the engine body and the amount of air supplied to the intake passage, and may decrease the torque limit injection amount according to the decrease in the estimated value of the EGR rate.

  When the EGR rate decreases, even if the fuel injection amount is the same, the torque generated by the engine increases. In the diesel engine of the present disclosure, the torque limit injection amount is decreased according to the decrease in the EGR rate. Thus, the fuel injection amount is controlled so that the torque does not exceed the upper limit as the EGR rate decreases. Thus, according to the diesel engine of the present disclosure, it is possible to realize fuel injection in which the torque generated by the engine does not exceed the upper limit.

1 is an overall configuration diagram of a diesel engine according to an embodiment of the present disclosure. It is a figure showing an example of a relation between an EGR rate and engine torque. It is a figure showing an example of setup of a torque limit injection quantity in a diesel engine according to this embodiment. It is a figure showing the relation between the torque limit injection quantity and the EGR rate in a certain engine speed. It is a flowchart explaining the setting process of the fuel injection quantity performed by ECU shown in FIG. FIG. 6 is a flowchart illustrating an example of a calculation process of a torque limit injection amount which is executed in step S30 of FIG. It is the figure which showed the relationship between gas pressure and gas amount.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference characters and description thereof will not be repeated.

<Overall configuration of diesel engine>
FIG. 1 is an overall configuration diagram of a diesel engine according to an embodiment of the present disclosure. Referring to FIG. 1, the diesel engine 1 includes an engine body 10, an air cleaner 20, an intercooler 26, an intake manifold 28, a supercharger 30, an exhaust manifold 50, and an EGR device 60.

  The engine body 10 includes a plurality of cylinders 12, a common rail 14, and a plurality of injectors 16. In the following, the diesel engine 1 is described as an in-line four-cylinder engine as an example, but the diesel engine 1 may be another cylinder layout (for example, V-type or horizontal) engine, and The number is also not limited to this. In each cylinder 12, a piston (not shown) is provided, and a combustion chamber is formed by the cylinder 12 and the piston.

  The plurality of injectors 16 are respectively provided to the plurality of cylinders 12, and each injector 16 is connected to the common rail 14. The fuel stored in the fuel tank (not shown) is pressurized to a predetermined pressure by a supply pump (not shown) and supplied to the common rail 14. The fuel supplied to the common rail 14 is injected from the injectors 16 into the combustion chamber at a predetermined timing.

  The air cleaner 20 is provided in the first intake pipe 22 and removes foreign matter contained in the air taken in from an intake port (not shown) provided at one end of the first intake pipe 22. The other end of the first intake pipe 22 is connected to the inlet of the compressor 32 of the turbocharger 30, and the outlet of the compressor 32 is connected to one end of the second intake pipe 24. The compressor 32 supercharges the air taken in through the first intake pipe 22 and supplies it to the second intake pipe 24.

  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. One end of the third intake pipe 27 is connected to the other end of the intercooler 26, and the other end of the third intake pipe 27 is connected to the intake manifold 28. The intake manifold 28 is connected to an intake port of each cylinder 12 of the engine body 10. An intake throttle valve may be provided upstream of the intake manifold 28.

  The exhaust manifold 50 is connected to the exhaust port of each cylinder 12 of the engine body 10. One end of the first exhaust pipe 52 is connected to the exhaust manifold 50, and the other end of the first exhaust pipe 52 is connected to the inlet of the turbine 36 of the turbocharger 30. Thus, the exhaust gas discharged from the exhaust port of each cylinder 12 is collected in the exhaust manifold 50 and then supplied to the turbine 36 via the first exhaust pipe 52.

  One end of the second exhaust pipe 54 is connected to the outlet of the turbine 36, and various catalysts (for example, NOx catalyst, DPF (Diesel particulate filter), DPNR (Diesel) not shown are connected to the other end of the second exhaust pipe 54. Catalysts such as Particulate-NOx Reduction) and mufflers are connected. Thereby, the exhaust gas discharged from the turbine 36 is discharged outside the vehicle via the second exhaust pipe 54, various catalysts, a muffler and the like.

  The compressor 32 and the turbine 36 constitute a supercharger 30. A compressor wheel 34 is provided in the housing of the compressor 32 and a turbine wheel 38 is provided in the housing of the turbine 36. The compressor wheel 34 and the turbine wheel 38 are connected by the connecting shaft 42 and integrally rotate. Thus, the compressor wheel 34 is rotationally driven by the exhaust energy of the exhaust gas supplied to the turbine wheel 38.

  The third intake pipe 27 and the exhaust manifold 50 are connected by the EGR device 60 without passing through the engine body 10. The EGR device 60 is configured to recirculate a part of the exhaust gas to the intake passage, and the exhaust gas is included in the intake gas to lower the combustion temperature to suppress the generation of NOx.

  The EGR device 60 includes an EGR valve 62, an EGR cooler 64, and an EGR passage 66. One end of the EGR passage 66 is connected to the third intake pipe 27, and the other end of the EGR passage 66 is connected to the exhaust manifold 50. Note that one end of the EGR passage 66 may be connected to the intake manifold 28, and the other end of the EGR passage 66 may be connected to the first exhaust pipe 52. The EGR passage 66 is provided with an EGR valve 62 and an EGR cooler 64.

  The EGR valve 62 shuts the EGR passage 66 to inhibit the flow of the EGR gas (exhaust gas returned to the intake side by the EGR device 60), and the open state which allows the EGR gas to flow in the EGR passage 66. And a switching valve capable of switching between Furthermore, in the open state, the EGR valve 62 can change the amount of EGR gas by changing the passage cross-sectional area (EGR opening). The EGR cooler 64 is a water-cooled or air-cooled heat exchanger that cools the EGR gas flowing through the EGR passage 66.

  When the EGR valve 62 is in the open state, a part of the exhaust gas collected in the exhaust manifold 50 is introduced into the EGR passage 66 as the EGR gas and is cooled by the EGR cooler 64, and then the flow rate is increased by the EGR valve 62. It is adjusted and supplied to the third intake pipe 27. By supplying the EGR gas to the third intake pipe 27, it is possible to reduce the temperature of the combustion gas in the combustion chamber and to suppress the generation amount of NOx. On the other hand, when the EGR valve 62 is in the closed state, the flow of the EGR gas is shut off.

  The diesel engine 1 further includes an air flow meter 102, an intake air temperature sensor 104, an intake pressure sensor 106, a rotational speed sensor 108, a water temperature sensor 110, an accelerator pedal position sensor 112, an atmospheric pressure sensor 114, and the outside air temperature. A sensor 116 and an ECU (Electronic Control Unit) 200 are provided.

  The air flow meter 102 detects an intake air amount FI flowing through the first intake pipe 22 and outputs the detected value to the ECU 200. The intake air temperature sensor 104 is an intake gas supplied to the intake manifold 28 (the air being output from the intercooler 26 when the EGR device 60 is not operating, and a mixture of air and exhaust gas when the EGR device 60 is operating) Is detected, and the detected value is output to ECU 200. The intake pressure sensor 106 detects the pressure PI of the intake gas supplied to the intake manifold 28, and outputs the detected value to the ECU 200.

  The rotation speed sensor 108 detects the rotation speed (engine rotation speed) NE of the output shaft of the diesel engine 1, and outputs the detected value to the ECU 200. Water temperature sensor 110 detects the temperature (engine cooling water temperature) TE of the cooling water of diesel engine 1, and outputs the detected value to ECU 200.

  The accelerator pedal position sensor 112 detects a depression amount of an accelerator pedal (not shown) (hereinafter also referred to as “accelerator opening degree”) AP, and outputs the detected value to the ECU 200. The atmospheric pressure sensor 114 detects the atmospheric pressure Pa, and outputs the detected value to the ECU 200. The outside air temperature sensor 116 detects the outside air temperature Ta, and outputs the detected value to the ECU 200.

  The ECU 200 includes a central processing unit (CPU), a read only memory (ROM) for storing processing programs, a random access memory (RAM) for temporarily storing data, and an input / output port for inputting / outputting various signals (see FIG. And performs predetermined arithmetic processing based on information stored in a memory (ROM and RAM) and information from various sensors. Then, the ECU 200 controls each device such as the injector 16 and the EGR device 60 based on the result of the arithmetic processing.

  In the present embodiment, the ECU 200 calculates the fuel injection amount from each injector 16 based on the accelerator opening AP, the engine speed NE, and the like. Further, the ECU 200 controls the EGR rate (intake engine supplied to the engine main body 10) by the EGR device 60 based on the engine rotational speed NE, the fuel injection amount, the environment information (atmospheric pressure Pa, outside air temperature Ta, engine cooling water temperature TE) etc. The ratio of the amount of EGR gas occupied in the gas is determined, and the opening degree of the EGR valve 62 is controlled so that the EGR rate is realized.

<Description of torque limit injection amount>
The torque (engine torque) generated by the diesel engine 1 can be increased by increasing the fuel injection amount from the injector 16, but in this embodiment, the torque is increased in order to prevent the generation of an excessive torque. The upper limit (torque limit injection amount) of the fuel injection amount is provided so as not to exceed the upper limit.

  By the way, in recent years, the demand for reduction of exhaust emission is increasing, and it may be necessary to operate the EGR device 60 up to the full load. Therefore, in the diesel engine 1 according to this embodiment, the full load performance is designed with the EGR device 60 operating, and the torque limit injection amount with the EGR device 60 operating is designed accordingly. There is a need.

  Here, the EGR rate may be reduced (including a cut) due to the driving environment (the high and low of the outside air temperature, etc.) and other fail safe. For example, when the intake gas becomes high temperature because the outside air temperature Ta is high, the exhaust gas also becomes high temperature, and the EGR rate is reduced to protect the EGR valve 62. Further, when the intake gas becomes low temperature because the outside air temperature Ta is low, the EGR rate is reduced to prevent corrosion due to condensation of the intake gas including the exhaust gas component. When the EGR rate decreases, the combustion efficiency improves, so even if the fuel injection amount is constant, the engine torque may increase and exceed the upper limit.

  FIG. 2 is a diagram showing an example of the relationship between the EGR rate and the engine torque TR. Referring to FIG. 2, the EGR rate value egrbse indicates the maximum EGR rate at full load, and this value is determined by the traveling conditions. As described above, in this embodiment, the full load performance is designed with the EGR device 60 in operation, and the fuel does not exceed the upper limit TL in the engine torque TR at the EGR rate (egrbse) at full load. The upper limit of the injection amount is set.

  In such a case, when the EGR rate decreases due to a change in the operating environment or the like while the fuel injection amount is constant, the amount of exhaust gas introduced into the combustion chamber decreases to improve the combustion efficiency, thereby improving the engine torque. TR rises, and the engine torque TR exceeds the upper limit TL (line L2).

  Therefore, in this embodiment, the upper limit (torque limit injection amount) of the fuel injection amount is provided such that engine torque TR does not exceed upper limit TL. In diesel engine 1 according to this embodiment, the EGR rate decreases. The torque limit injection amount is decreased according to the decrease of the EGR rate so that the engine torque TR does not exceed the upper limit TL. Thus, the fuel injection amount is controlled so that the engine torque TR does not exceed the upper limit TL.

  FIG. 3 is a view showing a setting example of the torque limit injection amount in the diesel engine 1 according to the present embodiment. Referring to FIG. 3, the vertical axis indicates the magnitude of the torque limit injection amount, and the horizontal axis indicates the engine speed NE. In this embodiment, the torque limit injection amount is set with the engine speed NE as a parameter.

  A line L0 indicates a torque limit injection amount when the EGR device 60 is inoperative (the EGR valve 62 is in a closed state). A line L1 indicates a torque limit injection amount when the EGR device 60 operates (the EGR valve 62 is in an open state). This line L1 indicates the torque limit injection amount when the EGR rate is the maximum EGR rate (egrbse). The value of such a torque limit injection amount is determined by experiment, simulation or the like, and is stored in the memory of the ECU 200 as a map.

  As shown in the figure, the torque limit injection amount (line L0) when the EGR device 60 is not operating is set to a value lower than the torque limit injection amount (line L1) when the EGR device 60 is operating. . Line L1 is the torque limit injection amount when the EGR rate is the maximum EGR rate (egrbse), but an interpolation value is adopted for the EGR rate lower than the maximum EGR rate (egrbse).

  FIG. 4 is a diagram showing the relationship between the torque limit injection amount and the EGR rate at a certain engine speed NE. Referring to FIG. 4, the vertical axis represents the magnitude of the torque limit injection amount, and the horizontal axis represents the EGR rate. Point P0 indicates the torque limit injection amount when the EGR device 60 is inoperative (EGR rate = 0) at this engine speed NE, and point P1 indicates that EGR rate = egrbse at this engine speed NE The torque limit injection amount when the EGR device 60 operates is shown. As the torque limit injection amount at the EGR rate between the point P0 and the point P1, an interpolation value (for example, linear interpolation) corresponding to the EGR rate is employed.

  Thus, by using the map shown in FIG. 3 and performing interpolation as shown in FIG. 4, torque limit injection according to the decrease in the EGR rate so that the engine torque TR does not exceed the upper limit according to the decrease in the EGR rate. The amount can be reduced.

<Process for setting fuel injection amount>
FIG. 5 is a flow chart for explaining the process of setting the fuel injection amount which is executed by the ECU 200 shown in FIG. The process shown in this flowchart is repeatedly performed during operation of the diesel engine 1.

  Referring to FIG. 5, ECU 200 obtains the detected value of accelerator opening degree AP from accelerator pedal position sensor 112, and obtains the detected value of engine speed NE from speed sensor 108 (step S10).

  Next, the ECU 200 calculates a required injection amount Qr indicating a required value of the fuel injection amount based on the acquired accelerator opening degree AP and the engine speed NE (step S20). Various known methods can be employed to calculate the required injection amount Qr based on the accelerator opening AP and the engine speed NE. For example, the ECU 200 reduces the fuel injection amount according to the increase of the engine rotational speed NE with respect to the equal accelerator opening, and controls the fuel injection amount according to the jerk (acceleration or jerk) It is possible to execute "control", "mood control" which makes the change of the fuel injection amount smooth with respect to the abrupt change of the accelerator opening AP.

  Then, when the required injection amount Qr is calculated based on the accelerator opening AP and the engine rotational speed NE, the ECU 200 calculates a torque limit injection amount indicating the upper limit of the fuel injection amount for the engine torque TR not to exceed the upper limit. (Step S30). As described above, in the diesel engine 1 according to this embodiment, the ECU 200 calculates the torque limit injection amount so that the torque limit injection amount decreases as the EGR rate decreases. The specific calculation process of the torque limit injection amount will be described in detail later.

  When the torque limit injection amount is calculated, the ECU 200 compares the required injection amount Qr calculated in step S20 with the torque limit injection amount (step S40). If it is determined that the required injection amount Qr is larger than the torque limit injection amount (YES in step S40), the ECU 200 sets the value of the torque limit injection amount to the required injection amount Qr (step S50). On the other hand, when it is determined that the required injection amount Qr is equal to or less than the torque limit injection amount (NO in step S40), the ECU 200 shifts the process to step S60 without executing step S50.

  Then, when it is determined in step S40 that the required injection amount Qr is larger than the torque limit injection amount, the ECU 200 performs the fuel injection of the injector 16 for the required injection amount Qr replaced with the torque limit injection amount in step S50. If it is determined that the required injection amount Qr is equal to or less than the torque limit injection amount in step S40, the required injection amount Qr calculated in step S20 is set as the fuel injection amount command value. (Step S60).

  FIG. 6 is a flow chart for explaining an example of the calculation process of the torque limit injection amount executed in step S30 of FIG. Referring to FIG. 6, the ECU 200 acquires the detected value of the engine rotational speed NE from the rotational speed sensor 108, and acquires the fuel injection amount (step S110). With regard to this fuel injection amount, for example, the fuel injection amount command value calculated one calculation cycle ago in step S60 of FIG. 5 may be obtained as the fuel injection amount, but at the time of the first calculation The required injection amount Qr is acquired as the fuel injection amount.

  Next, the ECU 200 acquires current environmental information (step S120). Specifically, the ECU 200 acquires the detected value of the atmospheric pressure Pa from the atmospheric pressure sensor 114, acquires the detected value of the outside air temperature Ta from the outside air temperature sensor 116, and detects the detected value of the engine cooling water temperature TE from the water temperature sensor 110. get.

  The ECU 200 is a target EGR rate indicating a target of the EGR rate (egrbse) at full load, based on the acquired engine rotational speed NE, fuel injection amount, environment information (atmospheric pressure Pa, outside temperature Ta, engine coolant temperature TE). The rate is determined (step S130). As an example, the EGR rate (egrbse) at full load is determined by stratification for each engine rotational speed, fuel injection amount and atmospheric pressure by experiment, simulation or the like, and is prepared in advance as a map. Then, the ECU 200 reads the EGR rate (egrbse) from the map based on the acquired engine rotational speed NE, fuel injection amount and atmospheric pressure Pa, and performs predetermined correction based on the acquired external temperature Ta and engine cooling water temperature TE. To determine the target EGR rate.

  Next, the ECU 200 acquires the detection value of the pressure (gas pressure) PI of the intake gas from the intake pressure sensor 106, and acquires the detection value of the temperature (gas temperature) TI of the intake gas from the intake temperature sensor 104. Further, the ECU 200 acquires a detected value of the intake air amount FI from the air flow meter 102 (step S140). Then, the ECU 200 calculates the amount (gas amount) of the intake gas supplied to the engine body 10 based on the acquired gas pressure PI and gas temperature TI (step S150). Specifically, as shown in FIG. 7, when the gas temperature TI is constant, the gas pressure PI and the amount of gas have a predetermined relationship, and the amount of gas corresponding to the gas pressure PI is the gas temperature The amount of gas can be calculated by correcting with TI.

  Then, the ECU 200 estimates an actual EGR rate based on the calculated gas amount and the acquired intake air amount FI (step S160). Specifically, the actual EGR rate can be estimated by dividing the value obtained by subtracting the intake air amount FI from the gas amount by the gas amount.

  The ECU 200 sets the opening degree of the EGR valve 62 as an operation amount to the deviation between the estimated EGR rate and the target EGR rate such that the EGR rate estimated in step S160 matches the target EGR rate determined in step S130. Feedback control (for example, proportional integral control) is executed (step S170). Thereby, the actual EGR rate (estimated EGR rate) is controlled to the target EGR rate.

  Then, ECU 200 determines the torque limit injection amount based on the estimated EGR rate calculated in step S160 using the relationship between the torque limit injection amount and the EGR rate described in FIGS. 3 and 4 (step S180). .

  As described above, in the present embodiment, the upper limit (torque limit injection amount) of the fuel injection amount is provided so that the engine torque TR does not exceed the upper limit. However, the engine torque TR exceeds the upper limit according to the decrease of the EGR rate. In order to prevent this, the torque limit injection amount is reduced as the EGR rate decreases. Therefore, according to this embodiment, it is possible to control the fuel injection amount so that the engine torque TR does not exceed the upper limit as the EGR rate decreases.

  Further, according to this embodiment, the torque limit injection amount is reduced based on the estimated EGR rate (actual value) estimated using the sensor detection value, not the target value (control target) of the EGR rate. Fuel injection in which the engine torque TR does not exceed the upper limit can be reliably realized.

  In the above embodiment, although the torque limit injection amount is determined based on the estimated EGR rate (actual value), the present disclosure is not limited to this, and step S130 in FIG. The torque limit injection amount may be determined on the basis of the target EGR rate determined in the above.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present disclosure is indicated not by the above description of the embodiment but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  Reference Signs List 1 engine, 10 engine body, 12 cylinders, 14 common rails, 16 injectors, 20 air cleaners, 22, 24, 27 intake pipes, 26 intercoolers, 28 intake manifolds, 30 superchargers, 32 compressors, 34 compressor wheels, 36 turbines, 38 turbine wheel, 42 connection shaft, 50 exhaust manifold, 52, 54 exhaust pipe, 60 EGR device, 62 EGR valve, 64 EGR cooler, 66 EGR passage, 102 airflow meter, 104 intake temperature sensor, 106 intake pressure sensor, 108 rotation Number sensor, 110 water temperature sensor, 112 accelerator pedal position sensor, 114 atmospheric pressure sensor, 116 outside air temperature sensor.

Claims (2)

An engine body having a combustion chamber;
An EGR device configured to connect an exhaust passage to an intake passage without passing through the engine body, and to recirculate part of exhaust gas to the intake passage;
A fuel injection device configured to inject fuel into the combustion chamber;
The control device controls the fuel injection device such that the fuel injection amount does not exceed a torque limit injection amount indicating the upper limit of the fuel injection amount determined according to the upper limit of the torque generated by the engine body.
The control apparatus reduces the torque limit injection amount as the EGR rate decreases so that the torque does not exceed the upper limit as the EGR rate decreases due to the EGR device.   The control device estimates the EGR rate using an intake gas amount sucked into the engine body and an air amount supplied to the intake passage, and the torque limit injection amount is calculated according to a decrease in the estimated value of the EGR rate. The diesel engine of claim 1, wherein the diesel engine is reduced.

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