JP2016113991A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly drive an internal combustion engine with a supercharger in a switch between stoichiometric combustion and lean combustion by suppressing an occurrence of a torque step.SOLUTION: A control device of an internal combustion engine controls an internal combustion engine with a supercharger. The control device includes torque suppression means which suppresses a torque from the internal combustion engine during a period from an activation of the supercharger to a rising-up of the torque, and torque suppression control means which carries out control which varies a torque suppression amount by the torque suppression means according to a case of stoichiometric combustion or a case of lean combustion.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, an internal combustion engine equipped with a supercharger has been widely used as an engine for vehicles. For example, Patent Document 1 discloses a control device for an engine with a supercharger, and in order to suppress the occurrence of a torque step from the start of the supercharger to the startup during vehicle acceleration, A technique for performing torque suppression control such as intake air amount control is disclosed.

JP 2008-014281 A

  Here, as a control of an internal combustion engine such as an engine, there is a case where control is performed to switch the combustion method of the internal combustion engine between stoichiometric combustion and lean combustion in accordance with the operating state of the vehicle. When switching between stoichiometric combustion and lean combustion, particularly when switching from stoichiometric combustion to lean combustion, the torque output of the internal combustion engine changes. However, with the conventional torque suppression amount, the torque suppression amount is relatively large, and the stagnation and depression of acceleration are not suppressed so much, and a torque step may occur. The occurrence of such a torque step is caused by the fact that the amount of torque suppression of the internal combustion engine does not correspond to a change in combustion method such as stoichiometric combustion or lean combustion. In particular, at the time of lean combustion, a torque step occurs due to the fact that no torque suppression method is set.

  The present invention has been made in view of the above, and an object of the present invention is to suppress the generation of a torque step even when switching between stoichiometric combustion and lean combustion in an internal combustion engine equipped with a supercharger. An object of the present invention is to provide a control device for an internal combustion engine that can smoothly drive the engine.

  In order to solve the above-described problems and achieve the above object, an internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus that controls an internal combustion engine having a supercharger. Torque suppression means that suppresses torque with respect to the internal combustion engine during the period from when the torque rises, and torque by the torque suppression means according to whether the combustion system of the internal combustion engine is stoichiometric combustion or lean combustion Torque suppression control means for performing control to change the suppression amount.

  According to the control device for an internal combustion engine according to the present invention, the torque suppression amount can be adjusted according to the case where the combustion of the engine is stoichiometric combustion or the case of lean combustion. In the equipped vehicle, even when switching between stoichiometric combustion and lean combustion, it is possible to suppress the generation of a torque step and drive the engine smoothly.

FIG. 1 is a schematic configuration diagram illustrating a vehicle on which torque suppression control according to the first embodiment is performed. FIG. 2 is a schematic configuration diagram showing an engine with a supercharger and related portions in the vehicle shown in FIG. FIG. 3 is a flowchart for explaining a torque suppression method at the time of switching combustion according to the first embodiment. FIG. 4 is a graph showing temporal changes in engine torque and turbine torque in stoichiometric combustion in each of the first embodiment and the prior art. FIG. 5 is a graph showing temporal changes in the engine speed, the turbine speed, and the torque ratio of the torque converter according to the first embodiment. FIG. 6 is a timing chart for explaining an example of a torque suppression method when switching combustion according to the first embodiment. FIG. 7 is a graph showing the engine speed dependency of the engine torque according to the first embodiment, and is a diagram for distinguishing the switching method between the stoichiometric combustion region and the lean combustion region. FIG. 8 is a table showing the degree of suppression during stoichiometric combustion and lean combustion shown in FIG. FIG. 9 is a flowchart for explaining a torque suppression method in switching of combustion according to the second embodiment. FIG. 10 is a timing chart for explaining an example of a torque suppression method in switching of combustion according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. The present invention is not limited to the embodiments described below.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a vehicle equipped with a shift control apparatus according to Embodiment 1. FIG. As shown in FIG. 1, a vehicle 1 includes an engine 11 with a supercharger that is an internal combustion engine, an automatic transmission 12, a propeller shaft 13, a differential gear 14, left and right drive shafts 15, and left and right drives. The vehicle includes a wheel 16, a hydraulic control unit 17, a vehicle speed sensor 18, an accelerator opening sensor 19, an engine ECU (Electronic Control Unit) 2, and an automatic transmission ECU 3. The engine 11 is provided with an engine speed sensor 11 a that measures the speed of the engine 11. The engine speed sensor 11a is electrically connected to the engine ECU 2 and outputs speed data to the engine ECU 2. Further, the automatic transmission 12 is provided with a torque converter 12 a connected to the crankshaft of the engine 11.

  FIG. 2 is a schematic configuration diagram of the turbocharged engine 11 shown in FIG. 1 and its related parts. First, the configuration of the engine 11 and its related parts will be described with reference to FIG.

  The engine 11 is configured by fastening a cylinder head on a cylinder block, and is formed by arranging a plurality of cylinders 21. A piston 22 is fitted to each cylinder 21 so as to be movable up and down. Each piston 22 is connected to a crankshaft (not shown) via a connecting rod 23.

  An intake manifold 25 is connected to the combustion chamber of the cylinder 21 via an intake port provided with an intake valve 24. An intake pipe 27 is connected to the intake manifold 25 via a surge tank 26. The intake pipe 27 is connected to an air intake port that takes in air Air. An air cleaner 28 is attached to the air intake. In the intake pipe 27, an electronic throttle 29 having a throttle valve 29 a is provided on the downstream side of the air cleaner 28.

  An exhaust manifold 31 is connected to the combustion chamber of the cylinder 21 via an exhaust port provided with an exhaust valve 30. An exhaust pipe 32 for exhausting the exhaust gas Ex is connected to the exhaust manifold 31. A start catalyst 33, a NOx occlusion reduction catalyst 34, and a NOx selective reduction catalyst 35 are sequentially attached to the exhaust pipe 32.

  A turbocharger 36 is provided in the intake pipe 27 and the exhaust pipe 32. The turbocharger 36 has a configuration in which a compressor 36a provided in the intake pipe 27 and a turbine 36b provided in the exhaust pipe 32 are integrally connected by a turbine shaft 36c. A water-cooled intercooler 37 is provided in the intake pipe 27 on the downstream side of the compressor 36a in the turbocharger 36 to cool intake air that has been supercharged by the compressor 36a and whose temperature has risen.

  The intake pipe 27 includes a pipe line 27a that bypasses the compressor 36a. The pipe 27a is provided with a blow-off valve 38 for releasing excess pressure between the turbocharger 36 and the throttle valve 29a. The exhaust pipe 32 includes a pipe line 32a that bypasses the turbine 36b, and a waste gate valve 39 for adjusting the amount of exhaust gas Ex flowing into the turbine 36b is provided in the pipe line 32a.

  Further, an EGR conduit 40 is provided between the intake pipe 27 and the exhaust pipe 32. The EGR pipe 40 is for allowing a part of the exhaust gas Ex discharged from the engine 11 to flow from the exhaust pipe 32 to the intake pipe 27 to be taken into the engine 11 as EGR (Exhaust Gas Recirculation) gas. The EGR pipe line 40 is provided with an EGR cooler 41 and an EGR valve 42.

  Inside the engine 11, an injector 43 that injects fuel into the intake port is mounted, and an ignition plug 44 that ignites the air-fuel mixture in the combustion chamber is mounted.

  Further, an air flow sensor 45 that detects the inflow amount of air Air is provided on the downstream side of the air cleaner 28. An intake air temperature sensor 46 that detects the temperature of the intake air supercharged by the compressor 36 a of the turbocharger 36 is provided upstream of the intercooler 37 in the intake pipe 27. The surge tank 26 is provided with a supercharging pressure sensor 47 that detects the supercharging pressure of the supercharged intake air. An air-fuel ratio sensor 48 that detects the oxygen concentration in the exhaust gas is provided upstream of the turbine 36 b in the exhaust pipe 32. The crankshaft of the engine 11 is provided with a crank angle sensor 49 for detecting a crank angle used for calculating the engine speed. The air flow sensor 45, the intake air temperature sensor 46, the supercharging pressure sensor 47, the air-fuel ratio sensor 48, and the crank angle sensor 49 are all electrically connected to the engine ECU 2 and output detection results to the engine ECU 2.

  As shown in FIG. 1, a stepped automatic transmission 12 is connected to the engine 11 via a torque converter 12a. The automatic transmission 12 has a propeller shaft 13 connected to the output side. Left and right drive shafts 15 are connected to the propeller shaft 13 via a differential gear 14. Further, left and right drive wheels 16 are connected to the left and right drive shafts 15 respectively.

  When the engine 11 is driven, the driving force is output from the crankshaft and input to the input shaft of the automatic transmission 12 via the torque converter 12a, and a predetermined shift is performed. Thereafter, the driving force is output from the output shaft of the automatic transmission 12 to the propeller shaft 13 and transmitted from the propeller shaft 13 to the left and right drive shafts 15 via the differential gear 14 to drive the left and right drive wheels 16. Can rotate. The automatic transmission 12 can perform a speed change operation by being controlled by the hydraulic control unit 17.

  The vehicle speed sensor 18 detects the traveling speed of the vehicle 1. The accelerator opening sensor 19 detects the accelerator opening according to the amount of depression of the accelerator pedal of the driver. Each of the vehicle speed sensor 18 and the accelerator opening sensor 19 is electrically connected to the engine ECU 2 and outputs a detection result to the engine ECU 2.

  The engine ECU 2 and the automatic transmission ECU 3 are physically composed of a well-known microcomputer including interfaces such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output. It is an electronic circuit. The functions of these ECUs are to load an application program stored in the ROM into the RAM and execute it by the CPU, operate the controlled object under the control of the CPU, and read and write data in the RAM and ROM. It is realized with. Further, the engine ECU 2 and the automatic transmission ECU 3 are configured to be able to communicate with each other, and transmit and receive various commands and detection results of various sensors.

  The engine ECU 2 receives detection results of the various sensors described above. The engine ECU 2 detects the operating state of the engine 11 based on the input detection result, and controls the fuel injection amount and injection timing by the injector 43, the ignition timing by the spark plug 44, and the like.

  The automatic transmission ECU 3 outputs a control signal to the hydraulic control unit 17 based on the detection result of the vehicle speed and the accelerator opening. The hydraulic control unit 17 controls the hydraulic mechanism of the automatic transmission 12 based on the control signal. Thereby, the automatic transmission 12 is shifted.

  As described above, the internal combustion engine including the vehicle drive device and the supercharging pressure control according to the first embodiment is configured.

(Control method of internal combustion engine with supercharging pressure control)
Next, a control method for an internal combustion engine equipped with a turbocharger by the internal combustion engine control apparatus according to Embodiment 1 of the present invention will be described. FIG. 3 shows a flowchart of an internal combustion engine control method according to the first embodiment.

  As shown in FIG. 3, first, the engine ECU 2 as a control device for the internal combustion engine collects information necessary for the control according to the first embodiment (step ST1). The information collected by the engine ECU 2 is specifically output from the accelerator pedal opening information output from the accelerator opening sensor 19, the vehicle speed information output from the vehicle speed sensor 18, and the engine speed sensor 11a of the engine 11. These are engine speed information, turbine speed information of the torque converter 12a, lockup (L / U) flag information, and the like.

  Next, engine ECU 2 determines whether or not slip has occurred in torque converter 12a. That is, engine ECU 2 determines whether or not the torque ratio of torque converter 12a is greater than 1 (step ST2). The determination of slippage of the torque converter 12a can also be made by the automatic transmission ECU 3 as a control device. When the torque ratio of the torque converter 12a is larger than 1 (step ST2: Yes), the process proceeds to step ST3.

  In step ST3, the engine ECU 2 determines whether combustion in the engine 11 is stoichiometric combustion. When the combustion of the engine 11 is stoichiometric combustion (step ST3: Yes), the process proceeds to step ST4. In step ST <b> 4, the engine ECU 2 performs first torque suppression control on the engine 11 to suppress torque output from the engine 11. Various torque suppression amounts for the engine 11 can be designed according to the air amount base (KL base), the torque ratio (T / C ratio) of the torque converter 12a, and the like. Details of the first torque suppression control will be described later. Thereafter, the control routine is terminated.

  On the other hand, when the engine ECU 2 determines in step ST2 that the slip of the torque converter 12a has not occurred, that is, when it is determined that the L / U flag of the torque converter 12a is raised and the torque ratio becomes 1 (step). ST2: No), the process proceeds to step ST5. In step ST3, when the engine ECU 2 determines that the combustion of the engine 11 is not stoichiometric combustion, that is, lean combustion (step ST3: No), the process proceeds to step ST5.

  In step ST5, the engine ECU 2 as the torque suppression control means suppresses the torque output from the engine 11 to the engine 11 to be smaller than that in the case of the first torque suppression control described above. I do. That is, the torque suppression amount of the second torque suppression control is smaller than the torque suppression amount of the first torque suppression control. Note that “the torque suppression amount is small” includes a case where the torque suppression amount is 0 and torque suppression is not performed. Details of the second torque suppression control will be described later. Thereafter, the control routine is terminated.

(Torque suppression control)
Next, the torque suppression control described above will be described. 4 and 6 are graphs showing an example of a change with time of the engine torque of the engine 11 and the turbine torque of the torque converter 12a. FIG. 5 is a graph showing an example of changes over time in the engine speed of the engine 11 and the turbine speed of the torque converter 12a, and changes over time in the torque ratio of the torque converter 12a.

  First, when the driver turns on the accelerator pedal while driving the vehicle 1 (time T0), the accelerator pedal opening information is output from the accelerator opening sensor 19 to the engine ECU 2. Based on the opening information of the accelerator pedal, the engine 11 performs stoichiometric combustion to increase the rotation speed, and the turbocharger 36 starts and the torque of the engine 11 increases with time.

  However, in the case of the change in turbine torque over time (thin dashed line) accompanying the change in engine actual torque over time (thin one-dot chain line) shown in FIG. 4, there are the following problems. That is, when the turbine torque and the engine torque coincide with each other (time T3), that is, when the torque rises (a portion surrounded by a broken line), a depression or stagnation in acceleration of the vehicle 1 is likely to occur. This is because in the engine 11 provided with the supercharger, the speed ratio of the torque converter 12a is increased and the torque ratio and the capacity coefficient are decreased before the maximum torque is output.

  Therefore, the engine ECU 2 controls the engine 11 to suppress the torque until the torque ratio of the torque converter 12a becomes 1, that is, until the torque rises, from the start of the turbocharger 36. At this time, as shown in the engine torque (thick solid line) and the turbine torque (thick broken line), at the time when the engine torque and the turbine torque coincide (time T3 / broken line enclosed part), the acceleration depression or stagnation in the vehicle 1 occurs. Does not occur. Therefore, drivability can be improved.

  Specifically, when the stoichiometric combustion continues until the torque ratio of the torque converter 12a becomes 1 (time T3), the first torque suppression that suppresses the torque with a large torque suppression amount with respect to the engine 11. Control is always performed. And the torque of the engine 11 is suppressed more than the engine actual torque (one-dot chain line) which is the original torque of the engine 11, and for example, changes with time shown by the engine torque (thick solid line) in FIG. Along with this, the turbine torque of the torque converter 12a is also suppressed, and for example, changes with time shown in the turbine torque (thick broken line) in FIG. At this time, the engine speed of the engine 11, the turbine speed of the torque converter 12a, and the torque ratio of the torque converter 12a change with time, for example, as shown in FIG. In FIG. 5, engine rotation (one-dot chain line) and turbine rotation (broken line) use the left vertical axis as an index, and the torque ratio of the torque converter 12a uses the right vertical axis as an index.

  On the other hand, as shown in FIG. 6, during the period from when the accelerator is turned on (time T0) until the torque ratio of the torque converter 12a becomes 1 (time T3), the combustion method of the engine 11 is stoichiometric and lean. Sometimes switching between combustion. Even in this case, torque suppression control is performed.

  That is, when the driver turns on the accelerator pedal while driving the vehicle 1 (time T0), the accelerator pedal opening degree information is output from the accelerator opening degree sensor 19 to the engine ECU 2. Based on the accelerator pedal opening information, the engine 11 is stoichiometrically combusted and the rotational speed of the engine 11 is increased. As a result, the torque of the engine 11 is also increased. In the first embodiment, the engine ECU 2 suppresses the torque of the engine 11 by a predetermined torque suppression amount. As a result, as shown by the engine torque (thick solid line), the torque of the engine 11 increases while being suppressed as time elapses. Along with this, the turbine torque of the torque converter 12a also increases.

  When the combustion of the engine 11 shifts from stoichiometric combustion to lean combustion (time T1), the engine ECU 2 controls the torque suppression amount for the engine 11 to be smaller than the torque suppression amount during the stoichiometric combustion described above. . Control for reducing the torque suppression amount by the engine ECU 2 is referred to as second torque suppression control. In the example shown in FIG. 4, the torque suppression amount for the engine 11 is set to zero. That is, the second torque suppression control is control that does not suppress torque. As a result, the engine torque during lean combustion becomes equal to the engine actual torque.

  Here, generally, the torque output by the engine 11 differs between stoichiometric combustion and lean combustion. Therefore, it is necessary to appropriately set the torque suppression amount, that is, the torque suppression amount to be suppressed with respect to the engine actual torque (load torque) in FIG. 6 according to the combustion method. Therefore, while the lockup mechanism of the torque converter 12a is accelerating in the off state, the torque suppression amount for the engine 11 during lean combustion and the torque suppression amount for the engine 11 during stoichiometric combustion are set to different suppression amounts. In the example shown in FIG. 6, the engine torque at the time of lean combustion is larger than the engine torque at the time of stoichiometric combustion, and the torque increases stepwise. Along with this, the turbine torque of the torque converter 12a also increases stepwise.

  At this time, since the torque of the engine 11 is suppressed at the time of stoichiometric combustion, at the time of switching the combustion system from stoichiometric combustion to lean combustion (time T1), compared to the torque step indicated by the conventional engine actual torque, In the first embodiment, the torque step can be reduced. Note that the ideal engine torque (thin solid line) in FIG. 6 shows an example of an ideal torque change that does not cause a torque step in the engine 11 when shifting from stoichiometric combustion to lean combustion. Similarly, the ideal turbine torque (thin broken line) shows an example of an ideal torque change in which a torque step in the turbine torque of the torque converter 12a does not occur at the time of transition from stoichiometric combustion to lean combustion. According to the first embodiment, the temporal changes in the engine torque and the turbine torque can be brought close to the temporal changes in the ideal engine torque and the ideal turbine torque, respectively, and the torque step can be reduced.

  Thereafter, when the combustion method in the engine 11 is switched from lean combustion to stoichiometric combustion (time T2), the engine ECU 2 performs first torque suppression that makes the torque suppression amount for the engine 11 larger than the torque suppression amount during lean combustion. Take control. In the example shown in FIG. 6, the torque suppression amount is made larger than zero. Thereby, the torque of the engine 11 is suppressed at the time of stoichiometric combustion. Therefore, the torque step can be reduced in the first embodiment as compared with the torque step indicated by the conventional engine actual torque at the combustion switching time (time T).

  Thereafter, the engine torque and the turbine torque coincide with each other, and the torque ratio of the torque converter 12a becomes 1 (time T3). From this point, torque suppression control for the engine 11 is not performed, and the torque suppression amount becomes zero. At the same time, the lockup mechanism in the torque converter 12a is turned on.

  As described above, by setting the torque suppression amount for the engine 11 during stoichiometric combustion larger than the torque suppression amount during lean combustion, the following effects are achieved. That is, the torque of the engine 11 during lean combustion is smaller than the torque during stoichiometric combustion. Therefore, when the stoichiometric combustion is switched to the lean combustion, the torque suppression amount for the engine 11 is decreased or the torque is increased as necessary. Thereby, the torque step at the time of switching the combustion method can be reduced. Therefore, when the torque converter 12a is slipping and the torque ratio is larger than 1, the change in the lower torque of the engine 11 can be smoothed when the stoichiometric combustion is switched to the lean combustion. Therefore, sudden acceleration fluctuations such as stagnation and depression in the acceleration of the vehicle 1 can be suppressed.

  Various methods can be adopted as a specific method for suppressing the torque applied to the engine 11 described above. Specifically, the torque of the engine 11 can be suppressed by the engine ECU 2 performing control to throttle the electronic throttle 29 in the engine 11 or to perform retard control of the ignition timing. That is, the electronic throttle 29, the spark plug 44, and the like, which are controlled variously by the engine ECU 2, function as torque suppression means.

  Here, when the torque suppression for the engine 11 at the time of stoichiometric combustion is performed by the retard control, the torque suppression amount at the time of lean combustion is made larger than when the torque is suppressed by the throttle of the electronic throttle 29. It is also possible. That is, when the torque is suppressed by retard control during the stoichiometric combustion, the amount of air in the intake pipe 27 is maintained more than when the torque is suppressed by the throttle of the electronic throttle 29. For this reason, the torque of the engine 11 when switching to lean combustion is greater when suppressed by retard control than when suppressed by the throttle of the electronic throttle 29. Therefore, when torque suppression is performed by retard control during stoichiometric combustion, it is necessary to increase the torque suppression amount in order to suppress the torque to the same level as the predetermined torque obtained by the throttle of the electronic throttle 29 during lean combustion. There is. That is, it is preferable to change the torque suppression amount in accordance with the torque suppression method during stoichiometric combustion.

(Torque suppression control according to switching pattern between stoichiometric combustion and lean combustion)
In the first embodiment described above, the case where the combustion method of the engine 11 is switched from stoichiometric combustion to stoichiometric combustion via lean combustion has been described. Performed with a pattern. FIG. 7 is a graph showing an area of stoichiometric combustion and an area of lean combustion in a graph showing the engine speed dependency of engine torque. FIG. 8 is a table showing a torque suppression method for each pattern for switching between stoichiometric combustion and lean combustion.

  As shown in FIG. 7, the switching pattern A is a pattern that switches from stoichiometric combustion to lean combustion while the rotational speed of the engine 11 increases. The switching pattern B is a pattern in which the lean combustion is switched to the stoichiometric combustion while the rotational speed of the engine 11 is increasing. The switching pattern C is a pattern that sequentially switches from stoichiometric combustion through lean combustion to stoichiometric combustion while the rotational speed of the engine 11 is increasing, and the first embodiment described above corresponds to the switching pattern C. The switching pattern D is a pattern that switches from stoichiometric combustion to lean combustion while the rotational speed of the engine 11 is decreasing. The switching pattern E is a pattern in which the lean combustion is switched to the stoichiometric combustion while the rotational speed of the engine 11 is decreasing.

  As shown in FIG. 8, in the switching patterns A, B, C, and E, the first torque suppression control having a relatively large torque suppression amount is performed during the stoichiometric combustion, and the torque suppression amount is determined during the lean combustion. A relatively small second torque suppression control is performed. On the other hand, in the switching pattern D, the first torque suppression control is performed in both the stoichiometric combustion and the lean combustion. In this way, the method of controlling the torque suppression amount for the engine 11 is changed according to the switching pattern between stoichiometric combustion and lean combustion.

(Embodiment 2)
Next, a control method for an internal combustion engine provided with supercharging pressure control according to Embodiment 2 of the present invention will be described. FIG. 9 shows a flowchart of the control method of the internal combustion engine according to the second embodiment. In the second embodiment, a torque suppression method corresponding to the above-described switching pattern D when the engine speed is switched from stoichiometric combustion to lean combustion will be described.

  As shown in FIG. 9, in the control method for the internal combustion engine according to the second embodiment, steps ST11 to ST14 are executed in the same manner as steps ST1 to ST4 in the first embodiment. If no slip has occurred in the torque converter 12a in step ST12 and the torque ratio is 1 (step ST12: No), the process proceeds to step ST16. Step ST16 is the same processing as step ST5 in the first embodiment.

  On the other hand, unlike the first embodiment, in the second embodiment, when it is determined in step ST13 that the engine 11 is performing lean combustion, the process proceeds to step ST15. In step ST15, the engine ECU 2 determines whether or not the accelerator pedal is returned based on information from the accelerator opening sensor 19. When the accelerator pedal is returned (step ST15: Yes), the process proceeds to step ST14 and the first torque suppression control is performed. On the other hand, when the accelerator pedal is not returned (step ST15: No), the process proceeds to step ST16 to perform the second torque suppression control.

  FIG. 10 is a graph showing changes in engine torque over time when the above-described control processing is performed. In FIG. 10, a thick solid line shows an example of the change over time of the engine torque of the engine 11 that is controlled according to the second embodiment, and a thin solid line shows an example of the change over time of the conventional engine torque.

  As shown in FIG. 10, in the state where the vehicle 1 is traveling normally, from the time when the accelerator pedal is returned (time T4), the rotational speed of the engine 11 starts to decrease and the engine torque also starts to decrease. Then, the torque suppression amount is not changed even when the engine 11 shifts from stoichiometric combustion to lean combustion with the accelerator pedal being returned by the driver. That is, in the second embodiment, the engine ECU 2 performs control so that the torque suppression amount is not changed even when the engine 11 shifts from stoichiometric combustion to lean combustion. As a result, the torque suppression amount during stoichiometric combustion and the torque suppression amount during lean combustion are maintained at the same level. Other configurations are the same as those of the first embodiment.

  In the second embodiment, when the combustion method is switched when the accelerator pedal is returned, the torque step as described above is generated, and a depression or stagnation in acceleration occurs. As a result, the reduction in driving force can be transmitted to the driver with further emphasis. This is because when the accelerator pedal is returned, it can be assumed that the driver's intention to accelerate is weakened.

  Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible. For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as necessary.

1 Vehicle 2 Engine ECU
3 Automatic transmission ECU
DESCRIPTION OF SYMBOLS 11 Engine 11a Engine speed sensor 12 Automatic transmission 12a Torque converter 18 Vehicle speed sensor 19 Accelerator opening sensor 29 Electronic throttle 36 Turbo supercharger 36a Compressor 36b Turbine 36c Turbine shaft 44 Spark plug

Claims (1)

A control device for an internal combustion engine for controlling an internal combustion engine having a supercharger,
Torque suppression means for suppressing torque with respect to the internal combustion engine in a period from when the turbocharger starts to when the torque rises;
An internal combustion engine comprising: a torque suppression control unit that performs control to change the amount of torque suppression by the torque suppression unit according to stoichiometric combustion and lean combustion; Engine control device.

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