Control device for internal combustion engine

Abstract

To suppress an increase in a difference between intake air amounts to be introduced to two cylinder groups.SOLUTION: A control device for an internal combustion engine executes: processing for calculating a first provisional value XR1 as a provisional value of a first upper limit value X1 on the basis of a temperature detected by a first temperature sensor (Step S110); processing for calculating a second provisional value XR2 as a provisional value of a second upper limit value X2 on the basis of a temperature detected by a second temperature sensor (Step S210); and processing for calculating the first provisional value XR1 as the first upper limit value X1 when the first provisional value XR1 is equal to or smaller than a second correction value XH2 obtained by multiplying the second provisional value XR2 by a correction coefficient VU, and calculating a value that is the second provisional value XR2 or larger and is smaller than the first provisional value XR1 as the first upper limit value X1 when the first provisional value XR1 is larger than the second correction value XH2 (Step S130).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for an internal combustion engine. [Background technology]

[0002] The internal combustion engine disclosed in Patent Document 1 has a first cylinder group, a first intake passage connected to the first cylinder group, and a first valve located in the first intake passage. The first valve is a so-called ISC valve (idle speed control valve). Intake air to be introduced into the first cylinder group flows through the first intake passage. The first valve adjusts the amount of intake air to be introduced into the first cylinder group during idle operation of the internal combustion engine. The internal combustion engine also has a second cylinder group, a second intake passage connected to the second cylinder group, and a second valve located in the second intake passage. The second valve is a so-called ISC valve. Intake air to be introduced into the second cylinder group flows through the second intake passage. The second valve adjusts the amount of intake air to be introduced into the second cylinder group during idle operation of the internal combustion engine. A control device for the internal combustion engine controls the first valve and the second valve individually. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-196431 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technique of individually controlling the amount of intake air introduced into the first cylinder group and the amount of intake air introduced into the second cylinder group as in Patent Document 1, the target value of the amount of intake air introduced into the first cylinder group may be set as a value within a certain allowable range. Similarly, the target value of the amount of intake air introduced into the second cylinder group may be set as a value within a certain allowable range. When adopting such an embodiment, if the upper limit values ​​of the ranges differ greatly between the two cylinder groups, a large difference may occur between the amount of intake air introduced into the first cylinder group and the amount of intake air introduced into the second cylinder group. The same applies to the case where the lower limit values ​​differ. In these cases, a difference may occur in the combustion pressure and the corresponding piston movement amount between the first cylinder group and the second cylinder group. As a result, the rotation of the crankshaft may become unstable. [Means for solving the problem]

[0005] A control device for an internal combustion engine for solving the above problem is applied to an internal combustion engine having a first cylinder group, a first intake passage that introduces intake air into the first cylinder group, a first throttle valve that adjusts the amount of intake air introduced into the first cylinder group, a first temperature sensor that detects the temperature of the intake air flowing through the first intake passage, a second cylinder group consisting of cylinders different from the first cylinder group, a second intake passage that introduces intake air into the second cylinder group, a second throttle valve that adjusts the amount of intake air introduced into the second cylinder group, and a second temperature sensor that detects the temperature of the intake air flowing through the second intake passage, and includes a first control process that calculates a first target value that is a target value for the amount of intake air to be introduced into the first cylinder group and controls the first throttle valve based on the first target value, a second control process that calculates a second target value that is a target value for the amount of intake air to be introduced into the second cylinder group and controls the second throttle valve based on the second target value, and a second temperature sensor that detects the temperature of the intake air flowing through the second intake passage. the first provisional value is calculated as a provisional value of a first upper limit value that is an upper limit value of the first target value based on the temperature detected by the second temperature sensor; a second provisional value is calculated as a provisional value of a second upper limit value that is an upper limit value of the second target value based on the temperature detected by the second temperature sensor; a first calculation process is performed to calculate the first provisional value as the first upper limit value when the first provisional value is equal to or less than a second correction value obtained by multiplying the second provisional value by a correction coefficient that is a predetermined value greater than 1, and to calculate a value that is equal to or greater than the second provisional value and less than the first provisional value as the first upper limit value when the first provisional value is greater than the second correction value; and a second calculation process is performed to calculate the second provisional value as the second upper limit value when the second provisional value is equal to or less than a first correction value obtained by multiplying the first provisional value by the correction coefficient, and to calculate a value that is equal to or greater than the first provisional value and less than the second provisional value as the second upper limit value when the second provisional value is greater than the first correction value.

[0006] In the above configuration, a large deviation may occur between the first provisional value and the second provisional value due to the difference between the temperature of the intake air in the first intake passage and the temperature of the intake air in the second intake passage, individual differences between the first temperature sensor and the second temperature sensor, etc. In this case, if the first provisional value and the second provisional value are adopted as the first upper limit value and the second upper limit value, the deviation between the upper limit values ​​will also become large.

[0007] According to the above configuration, when the first provisional value is larger than the second provisional value by a certain percentage or more, a value whose difference with respect to the second provisional value is smaller than the first provisional value is calculated as the first upper limit value. That is, in a situation in which the difference between the first upper limit value and the second upper limit value becomes large when the upper limit value is calculated based on each temperature sensor, each upper limit value is calculated so that the difference between the two is small. Therefore, it is possible to suppress the deviation between the first upper limit value and the second upper limit value, and thus the increase in the difference between the amount of intake air introduced into the first cylinder group and the amount of intake air introduced into the second cylinder group.

[0008] The control device for the internal combustion engine may, in the first calculation process, calculate the smaller of the first provisional value and the second correction value as the first upper limit value, and, in the second calculation process, calculate the smaller of the second provisional value and the first correction value as the second upper limit value.

[0009] According to the above configuration, the value obtained by dividing the larger of the first and second upper limit values ​​by the smaller of the first and second upper limit values ​​is equal to or smaller than the correction coefficient. That is, the ratio of the first and second upper limit values ​​can be made closer to 1 than the ratio represented by the correction coefficient.

[0010] A control device for an internal combustion engine for solving the above problem is applied to an internal combustion engine having a first cylinder group, a first intake passage that introduces intake air into the first cylinder group, a first throttle valve that adjusts the amount of intake air introduced into the first cylinder group, a second cylinder group consisting of cylinders different from the first cylinder group, a second intake passage that introduces intake air into the second cylinder group, a second throttle valve that adjusts the amount of intake air introduced into the second cylinder group, and a crank position sensor that detects a rotational position of a crankshaft, and includes a first control process that calculates a first target value that is a target value for the amount of intake air to be introduced into the first cylinder group and controls the first throttle valve based on the first target value, a second control process that calculates a second target value that is a target value for the amount of intake air to be introduced into the second cylinder group and controls the second throttle valve based on the second target value, and a first preliminary process for calculating a first provisional value as a provisional value of a first lower limit value that is a lower limit value of the second target value, based on the rotational speed of the crankshaft; a second preliminary process for calculating a second provisional value as a provisional value of a second lower limit value that is a lower limit value of the second target value, based on the rotational speed of the crankshaft; a first calculation process for calculating the first provisional value as the first lower limit value when the first provisional value is equal to or greater than a second correction value obtained by multiplying the second provisional value by a correction coefficient that is predetermined to be a value smaller than 1, and for calculating a value that is equal to or less than the second provisional value and greater than the first provisional value as the first lower limit value when the first provisional value is smaller than the second correction value; and a second calculation process for calculating the second provisional value as the second lower limit value when the second provisional value is equal to or greater than a first correction value obtained by multiplying the first provisional value by the correction coefficient, and for calculating a value that is equal to or less than the first provisional value and greater than the second provisional value as the second lower limit value when the second provisional value is smaller than the first correction value.

[0011] In the above configuration, if the rotation speed of the crankshaft fluctuates, the rotation speed referred to in calculating the first provisional value may differ from the rotation speed referred to in calculating the second provisional value. Due to such a reason, a large deviation may occur between the first provisional value and the second provisional value. In this case, if the first provisional value and the second provisional value are used as the first lower limit value and the second lower limit value, the deviation between the respective lower limit values ​​will also become large.

[0012] According to the above configuration, when the first provisional value is smaller than the second provisional value by a certain percentage or more, a value whose difference with respect to the second provisional value is smaller than the first provisional value is calculated as the first lower limit value. That is, in a situation in which the difference between the first lower limit value and the second lower limit value becomes large when the lower limit value is calculated based on the rotation speed of the crankshaft, each lower limit value is calculated so that the difference between the two values ​​becomes small. Therefore, it is possible to suppress the deviation between the first lower limit value and the second lower limit value, and thus the increase in the difference between the amount of intake air introduced into the first cylinder group and the amount of intake air introduced into the second cylinder group.

[0013] The control device for the internal combustion engine may, in the first calculation process, calculate the larger of the first provisional value and the second correction value as the first lower limit value, and, in the second calculation process, calculate the larger of the second provisional value and the first correction value as the second lower limit value.

[0014] According to the above configuration, the value obtained by dividing the smaller of the first and second lower limits by the larger of the first and second lower limits is equal to or greater than the correction coefficient. That is, the ratio of the first and second lower limits can be made closer to 1 than the ratio represented by the correction coefficient. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of an internal combustion engine. [Diagram 2] FIG. 2 is a flowchart showing a processing procedure of the first upper limit process and the second upper limit process. [Diagram 3] FIG. 3 is a flowchart showing a processing procedure of the first lower limit process and the second lower limit process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to the drawings. <General configuration of internal combustion engine> As shown in Fig. 1, the vehicle 300 has an internal combustion engine 100. The internal combustion engine 100 is located in an engine room of the vehicle 300. The internal combustion engine 100 is a drive source for the vehicle 300. The internal combustion engine 100 has a first bank section 110, a second bank section 120, and a crankshaft 130. Note that, hereinafter, when the first bank section 110 and the second bank section 120 are described without distinction with respect to each section of the internal combustion engine 100 and the control configuration described below, the prefixes "first" and "second" are omitted and the reference numerals are also omitted.

[0017] The first bank portion 110 has a first cylinder group 10, a first intake passage 11, a first exhaust passage 12, a first turbocharger 13, a first intercooler 14, and a first throttle valve 15. The first bank portion 110 also has a first EGR passage 16, a first EGR valve 17, three first spark plugs 18, and three first injectors 19.

[0018] The first cylinder group 10 is a group of cylinders consisting of three cylinders 10A. The cylinders 10A are spaces for burning a mixture of fuel and intake air. Although not shown in the figure, the cylinders 10A house pistons. The pistons reciprocate within the cylinders 10A. The pistons are connected to a crankshaft 130 via connecting rods. The crankshaft 130 rotates in response to the movement of the pistons. Although not shown in the figure, the crankshaft 130 is located within a crankcase. Lubricating oil is stored at the bottom of the crankcase.

[0019] A first spark plug 18 is provided for each cylinder 10A of the first cylinder group 10. The first spark plug 18 ignites the air-fuel mixture in the cylinder 10A. A first injector 19 is provided for each cylinder 10A of the first cylinder group 10. The first injector 19 supplies fuel to the cylinder 10A.

[0020] The first intake passage 11 is connected to each cylinder 10A of the first cylinder group 10. The first intake passage 11 is a passage for introducing intake air into the first cylinder group 10. The first intercooler 14 is located in the middle of the first intake passage 11. The first intercooler 14 cools the intake air. The first throttle valve 15 is located downstream of the first intercooler 14 in the first intake passage 11. The opening degree of the first throttle valve 15 is adjustable. The amount of intake air introduced into the first cylinder group 10 changes depending on the opening degree of the first throttle valve 15. That is, the first throttle valve 15 adjusts the amount of intake air introduced into the first cylinder group 10.

[0021] The first exhaust passage 12 is connected to each cylinder 10A of the first cylinder group 10. The first exhaust passage 12 is a passage for discharging exhaust gas from the first cylinder group 10. The first supercharger 13 is provided across the first intake passage 11 and the first exhaust passage 12. Specifically, the first supercharger 13 has a first compressor wheel 13A and a first turbine wheel 13B. The first compressor wheel 13A is located upstream of the first intake passage 11 as viewed from the first intercooler 14. The first turbine wheel 13B is located midway through the first exhaust passage 12. The first turbine wheel 13B rotates in response to the flow of exhaust gas. The first compressor wheel 13A rotates integrally with the first turbine wheel 13B. The intake air is supercharged by the rotation of the first compressor wheel 13A. Although not shown, a bypass passage that detours around the first turbine wheel 13B exists in the first exhaust passage 12. A wastegate valve that opens and closes the bypass passage exists in this bypass passage.

[0022] The first EGR passage 16 connects an upstream portion of the first exhaust passage 12 as viewed from the first turbine wheel 13B with a downstream portion of the first intake passage 11 as viewed from the first throttle valve 15. The first EGR passage 16 is a passage for recirculating the exhaust gas flowing through the first exhaust passage 12 to the first intake passage 11. Hereinafter, the exhaust gas recirculated from the exhaust passage to the intake passage is referred to as EGR gas. The first EGR valve 17 is located in the middle of the first EGR passage 16. The opening degree of the first EGR valve 17 is adjustable. The amount of EGR gas recirculated to the first intake passage 11 changes depending on the opening degree of the first EGR valve 17. That is, the first EGR valve 17 adjusts the amount of EGR gas recirculated to the first intake passage 11.

[0023] The second bank section 120 has a symmetrical configuration to the first bank section 110. Therefore, only an outline of the configuration of the second bank section 120 will be described, and detailed description will be simplified or omitted. The second bank section 120 has a second cylinder group 20, a second intake passage 21, a second exhaust passage 22, a second supercharger 23, a second intercooler 24, and a second throttle valve 25. The second bank section 120 also has a second EGR passage 26, a second EGR valve 27, three second spark plugs 28, and three second injectors 29.

[0024] The second cylinder group 20 is a group of cylinders consisting of three cylinders 20A different from the first cylinder group 10. The pistons in the cylinders 20A are connected to the crankshaft 130. A second spark plug 28 is provided for each cylinder 20A of the second cylinder group 20. A second injector 29 is provided for each cylinder 20A of the second cylinder group 20. The second intake passage 21 is a passage for introducing intake air into the second cylinder group 20, and is connected to each cylinder 20A of the second cylinder group 20. The second intake passage 21 is completely independent of the first intake passage 11. The second intercooler 24 is located in the middle of the second intake passage 21. The second throttle valve 25 is located downstream of the second intercooler 24 in the second intake passage 21. The second throttle valve 25 adjusts the amount of intake air introduced into the second cylinder group 20.

[0025] The second exhaust passage 22 is connected to each cylinder 20A of the second cylinder group 20. The second supercharger 23 has a second compressor wheel 23A and a second turbine wheel 23B. The second compressor wheel 23A is located upstream of the second intake passage 21 as viewed from the second intercooler 24. The second turbine wheel 23B is located midway through the second exhaust passage 22.

[0026] The second EGR passage 26 connects an upstream portion of the second exhaust passage 22 as viewed from the second turbine wheel 23B to a downstream portion of the second intake passage 21 as viewed from the second throttle valve 25. The second EGR valve 27 is located midway through the second EGR passage 26. The second EGR valve 27 adjusts the amount of EGR gas recirculated to the second intake passage 21.

[0027] The internal combustion engine 100 has a crank position sensor 93, a first temperature sensor 62, a first air flow meter 63, a second temperature sensor 72, and a second air flow meter 73. The crank position sensor 93 is located near the crankshaft 130. The crank position sensor 93 detects the rotational position CR of the crankshaft 130. The first temperature sensor 62 is located upstream of the first compressor wheel 13A in the first intake passage 11. The first temperature sensor 62 detects the temperature T1 of the intake air flowing through the installation location of the first temperature sensor 62 in the first intake passage 11 (hereinafter referred to as the first temperature). The first air flow meter 63 is located upstream of the first temperature sensor 62 in the first intake passage 11. The first air flow meter 63 detects the amount of intake air flowing into the first intake passage 11 (hereinafter referred to as the first intake amount) G1. The second temperature sensor 72 is located upstream of the second intake passage 21 as viewed from the second compressor wheel 23A. The second temperature sensor 72 detects a temperature (hereinafter referred to as the second temperature) T2 of the intake air flowing through a location in the second intake passage 21 where the second temperature sensor 72 is installed. The second air flow meter 73 is located upstream of the second temperature sensor 72 in the second intake passage 21. The second air flow meter 73 detects an amount (hereinafter referred to as the second intake air amount) G2 of the intake air flowing into the second intake passage 21.

[0028] The vehicle 300 has a vehicle speed sensor 94, an accelerator sensor 95, and an atmospheric pressure sensor 96. The vehicle speed sensor 94 detects the traveling speed of the vehicle 300 as a vehicle speed SP. The accelerator sensor 95 detects the depression amount of the accelerator pedal of the vehicle 300 as an accelerator operation amount ACC. The atmospheric pressure sensor 96 detects the atmospheric pressure P at the point where the vehicle 300 is traveling.

[0029] <Outline of the control device> As shown in FIG. 1, the vehicle 300 has a control device 200. The control device 200 may be configured as one or more processors that execute various processes according to a computer program (software). The control device 200 may be configured as one or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that execute at least a part of the various processes, or a circuit including a combination thereof. The processor includes a CPU 201 and memories such as a RAM and a ROM 202. The memory stores program codes or instructions that are configured to cause the CPU 201 to execute the processes. The memory, i.e., the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. The control device 200 has a storage device that is an electrically rewritable non-volatile memory.

[0030] The control device 200 repeatedly receives detection signals from various sensors in the vehicle 300. Specifically, the control device 200 receives detection signals for the following parameters: Vehicle speed SP detected by vehicle speed sensor 94 Acceleration amount ACC detected by accelerator sensor 95 Atmospheric pressure P detected by the atmospheric pressure sensor 96 The rotational position CR of the crankshaft 130 detected by the crank position sensor 93 A first temperature T1 detected by the first temperature sensor 62 The first intake air amount G1 detected by the first air flow meter 63 A second temperature T2 detected by the second temperature sensor 72 The second intake air volume G2 detected by the second air flow meter 73 The control device 200 calculates the following parameters from time to time based on detection signals received from various sensors. The control device 200 calculates the engine speed NE, which is the rotation speed of the crankshaft 130, based on the rotation position CR of the crankshaft 130. The control device 200 also calculates an engine load factor (hereinafter referred to as a first engine load factor) KL1 of the first bank portion 110 based on the engine speed NE and a first intake air amount G1. The control device 200 also calculates an engine load factor (hereinafter referred to as a second engine load factor) KL2 of the second bank portion 120 based on the engine speed NE and a second intake air amount G2. The engine load factor is a parameter that determines the amount of intake air filled into a cylinder, and is a value obtained by dividing the amount of intake air flowing into one cylinder per combustion cycle by a reference intake air amount. The reference intake air amount changes depending on the engine speed NE.

[0031] <Overall control of the first bank> The control device 200 controls various parts of the first bank section 110. For example, the control device 200 controls the first spark plug 18 and the first injector 19. As a result, the control device 200 performs a combustion operation in which the mixture is repeatedly burned in the first cylinder group 10. The control device 200 may perform a fuel cut to stop fuel injection depending on the driving situation, such as when the vehicle 300 is decelerating. The control device 200 also controls the first EGR valve 17. When controlling the first EGR valve 17, the control device 200 calculates a first target EGR rate W1, which is a target value of the EGR rate in the first bank section 110, based on the engine speed NE and the first engine load rate KL1, etc. Then, the control device 200 adjusts the opening degree of the first EGR valve 17 based on the first intake amount G1, etc., so that the actual EGR rate becomes the first target EGR rate W1. The EGR rate is the amount of EGR gas recirculated to the intake passage divided by the total amount of gas flowing into the cylinder group, which is the sum of the amount of EGR gas recirculated to the intake passage and the amount of intake air into which the EGR gas merges.

[0032] The control device 200 also performs a first control process for controlling the first throttle valve 15. In the first control process, the control device 200 repeats the following two operations. First, the control device 200 calculates a first target value A1, which is a target value for the amount of intake air to be introduced into the first cylinder group 10. Then, the control device 200 controls the first throttle valve 15 based on the first target value A1. That is, the control device 200 adjusts the opening degree of the first throttle valve 15 so that the amount of intake air to be introduced into the first cylinder group 10 becomes the first target value A1. In this embodiment, the amount of intake air to be introduced into the cylinder group refers to the amount of intake air passing through the throttle valve. In calculating the first target value A1, the control device 200 first calculates a basic value of the first target value A1 based on the accelerator operation amount ACC, the engine rotation speed NE, the first intake air amount G1, and the like. Then, the control device 200 calculates the first target value A1 based on this basic value and the latest information on the allowable calculation range of the first target value A1. That is, when the basic value is between the upper limit and lower limit of the calculation range, the control device 200 sets the basic value as the first target value A1 as it is. When the basic value is larger than the upper limit, the control device 200 sets the upper limit as the first target value A1. When the basic value is smaller than the lower limit, the control device 200 sets the lower limit as the first target value A1.

[0033] <Overall control of the second bank> The control device 200 controls various parts of the second bank section 120. The control device 200 controls various parts of the second bank section 120 independently of the first bank section 110. That is, the control device 200 calculates target values ​​for controlling various parts of the second bank section 120 in addition to controlling various parts of the first bank section 110, and controls various parts of the second bank section 120 based on the target values. The control device 200 controls the second spark plug 28 and the second injector 29, as well as the second EGR valve 27, in the same manner as the first bank section 110. When controlling the second EGR valve 27, the control device 200 calculates a second target EGR rate W2, which is a target value of the EGR rate in the second bank section 120, based on the engine speed NE, the second engine load rate KL2, etc.

[0034] The control device 200 also performs a second control process for controlling the second throttle valve 25. In the second control process, the variables used or calculated in the first control process are replaced with variables for controlling the second throttle valve 25. That is, in the second control process, the control device 200 calculates a second target value A2, which is a target value for the amount of intake air introduced into the second cylinder group 20. Then, the control device 200 adjusts the opening degree of the second throttle valve 25 so that the amount of intake air introduced into the second cylinder group 20 becomes the second target value A2. When calculating the second target value A2, the control device 200 calculates a basic value of the second target value A2 based on the accelerator operation amount ACC, the engine speed NE, the second intake amount G2, and the like. Then, the control device 200 calculates the second target value A2 based on this basic value and the latest information on the allowable calculation range of the second target value A2.

[0035] <Outline of upper limit calculation method> A method for calculating the calculation range of the first target value A1 and the calculation range of the second target value A2 will be described below. Note that the process for calculating the upper limit value (hereinafter referred to as the first upper limit value) X1 of the calculation range of the first target value A1 is related to the process for calculating the upper limit value (hereinafter referred to as the second upper limit value) X2 of the calculation range of the second target value A2. Also, the process for calculating the lower limit value (hereinafter referred to as the first lower limit value) Y1 of the calculation range of the first target value A1 is related to the process for calculating the lower limit value (hereinafter referred to as the second lower limit value) Y2 of the calculation range of the second target value A2. In light of this, the processes related to the upper limit value will be described below first, and then the processes related to the lower limit value will be described below.

[0036] The control device 200 can execute a first upper limit process for calculating the first upper limit value X1. The first upper limit process includes a first pre-processing for the upper limit and a first calculation process. In the first pre-processing for the upper limit, the control device 200 calculates a first provisional value XR1 as a provisional value of the first upper limit value X1 based on the first temperature T1 detected by the first temperature sensor 62. In addition, in the first calculation process for the upper limit, the control device 200 calculates the first upper limit value X1. At that time, the control device 200 takes into consideration the value of a second provisional value XR2, which is a provisional value of the second upper limit value X2 calculated in a second upper limit process described later. That is, when the first provisional value XR1 is equal to or less than a second correction value XH2 obtained by correcting the second provisional value XR2, the control device 200 calculates the first provisional value XR1 as it is as the first upper limit value X1. On the other hand, when the first provisional value XR1 is greater than the second correction value XH2, the control device 200 calculates a value that is greater than or equal to the second provisional value XR2 and less than the first provisional value XR1 as the first upper limit value X1.

[0037] The control device 200 can execute a second upper limit process for calculating the second upper limit value X2. In the second upper limit process, each variable used or calculated in the first upper limit process is replaced with a variable for calculating the second upper limit value X2. That is, the second upper limit process includes a second pre-processing for the upper limit and a second calculation process. In the second pre-processing for the upper limit, the control device 200 calculates the second provisional value XR2 based on the second temperature T2 detected by the second temperature sensor 72. In the second calculation process for the upper limit, if the second provisional value XR2 is equal to or less than the first correction value XH1 obtained by correcting the first provisional value XR1, the control device 200 calculates the second provisional value XR2 as the second upper limit value X2 as it is. On the other hand, when the second provisional value XR2 is larger than the first correction value XH1, the control device 200 calculates a value that is equal to or larger than the first provisional value XR1 and smaller than the second provisional value XR2 as the second upper limit value X2.

[0038] The control device 200 stores a setting map in advance as information required for the first upper limit process and the second upper limit process (hereinafter, referred to as required information for the upper limit). Here, the amount of intake air that can be charged into the cylinder has a limit determined by the specifications of the internal combustion engine 100, such as the volume of the cylinder and the supercharging capacity according to the shape and size of each wheel in the supercharger. Regarding the amount of intake air introduced into the cylinder group, a value that can be considered optimal as the maximum amount of the intake air determined by the above limitations is called the maximum introduction value. Although the maximum introduction value is basically determined by the specifications of various parts of the internal combustion engine 100 as described above, in detail, it changes depending on the state of the intake air according to the environmental field such as temperature and air pressure. The setting map represents the relationship between the temperature of the intake air, the atmospheric pressure, and the maximum introduction value. In the setting map, basically, if the atmospheric pressure is the same, the higher the temperature of the intake air, the smaller the maximum introduction value. In addition, in the setting map, basically, if the temperature of the intake air is the same, the lower the atmospheric pressure, the smaller the maximum introduction value. The intake air temperature specified in the set map is for a location in the intake passage upstream of the compressor wheel, and the set map is created based on, for example, an experiment or a simulation.

[0039] The control device 200 prestores a protection limit value and an upper limit circuit limit value as necessary information for the upper limit. The protection limit value is a maximum value permissible with respect to the amount of intake air introduced into the cylinder group from the viewpoint of protecting various components by avoiding the flow of an excessive amount of gas in the entire intake system and exhaust system of the internal combustion engine 100. The upper limit circuit limit value is a limit value that is not considered to be an excessive value caused by an abnormality in the circuit of the control device 200. The protection limit value and the upper limit circuit limit value are calculated, for example, based on an experiment or a simulation.

[0040] The control device 200 prestores an upper limit correction coefficient (hereinafter, referred to as an upper limit coefficient) VU as necessary information for the upper limit. The upper limit coefficient VU is predefined as a value greater than 1. In this embodiment, the upper limit coefficient VU is 1.2. The upper limit coefficient VU is defined as a value such as the following, for example, based on an experiment or a simulation. Now, assume that there is a difference between the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20. In this case, a difference may occur in the combustion pressure and the piston movement amount corresponding thereto between the first cylinder group 10 and the second cylinder group 20. As a result, the time fluctuation of the engine speed NE may become large when the internal combustion engine 100 is in a steady state. When the internal combustion engine 100 is in a steady state, it is not a transitional period in which the engine speed NE changes according to the acceleration or deceleration of the vehicle 300, but a period in which the engine speed NE is approximately constant. The value obtained by dividing the larger of the amount of intake air introduced into the first cylinder bank 10 and the amount of intake air introduced into the second cylinder bank 20 by the smaller of the two is referred to as the upper limit specific value. The upper limit coefficient VU is the maximum value of the upper limit specific value that can suppress the time variation of the engine speed NE within an allowable range when the internal combustion engine 100 is in a steady state.

[0041] <Specific Processing Procedures for the First Upper Limit Process and the Second Upper Limit Process> When the engine speed NE is greater than zero, the control device 200 repeatedly executes the first upper limit process. As shown in FIG. 2(a), when the control device 200 starts the first upper limit process, the control device 200 first executes the process of step S110. In step S110, the control device 200 calculates a first provisional value XR1. Specifically, the control device 200 refers to the setting map, the latest first temperature T1, and the latest atmospheric pressure P. Then, the control device 200 calculates an introduction maximum value corresponding to the latest first temperature T1 and the latest atmospheric pressure P in the setting map. After this, the control device 200 compares the introduction maximum value, the protection limit value, and the circuit limit value for the upper limit. Then, the control device 200 calculates the smallest value among them as the first provisional value XR1. After calculating the first provisional value XR1, the control device 200 advances the process to step S120. The process of step S110 is a first pre-processing for the upper limit.

[0042] In step S120, the control device 200 calculates the second correction value XH2. Specifically, the control device 200 refers to the latest second provisional value XR2 calculated in the second upper limit process. Then, the control device 200 multiplies this second provisional value XR2 by an upper limit coefficient VU. Then, the control device 200 sets the obtained value as the second correction value XH2. After calculating the second correction value XH2, the control device 200 advances the process to step S130.

[0043] In step S130, the control device 200 calculates a first upper limit value X1. Specifically, the control device 200 sets the smaller value of the first provisional value XR1 calculated in step S110 and the second correction value XH2 calculated in step S120 as the first upper limit value X1. After calculating the first upper limit value X1, the control device 200 temporarily ends a series of processes for the first upper limit. Thereafter, the control device 200 performs the process of step S110 again. The processes of steps S120 and S130 are the first calculation process for the upper limit.

[0044] When the engine speed NE is greater than zero, the control device 200 repeatedly executes the second upper limit process in parallel with the first upper limit process. That is, as shown in FIG. 2B, the control device 200 first calculates a second provisional value XR2 in step S210. The calculation method of the second provisional value XR2 is the same as the calculation method of the first provisional value XR1, except that the second temperature T2 is used instead of the first temperature T1 used in the first upper limit process. In the following step S220, the control device 200 refers to the latest first provisional value XR1 calculated in the first upper limit process, and multiplies the first provisional value XR1 by the upper limit coefficient VU to obtain a first correction value XH1. In the following step S230, the control device 200 sets the smaller value of the second provisional value XR2 calculated in step S210 and the first correction value XH1 calculated in step S220 as the second upper limit value X2. Then, the control device 200 temporarily ends the series of processes for the second upper limit process. The process of step S210 is a second pre-processing for the upper limit. The processes of steps S220 and S230 are a second calculation process for the upper limit.

[0045] <Outline of calculation method for lower limit> The control device 200 can execute a first lower limit process. The first lower limit process is a process for calculating a first lower limit value Y1, which is a lower limit value of a calculation range of the first target value A1. In the above-mentioned first upper limit process, the first upper limit value X1 is calculated so as to reduce the deviation between the first upper limit value X1 and the second upper limit value X2. Similarly, the first lower limit process calculates the first lower limit value Y1 so as to reduce the deviation between the first lower limit value Y1 and the second lower limit value Y2, which is the lower limit value of the second target value A2. The first lower limit process includes a first preliminary process for the lower limit and a first calculation process. In the first preliminary process for the lower limit, the control device 200 calculates a first provisional value YR1 as a provisional value of the first lower limit value Y1 based on the engine rotation speed NE. In the first calculation process for the lower limit, the control device 200 calculates the first lower limit value Y1. At that time, the control device 200 takes into consideration the value of the second provisional value YR2, which is a provisional value of the second lower limit value Y2 calculated in the second lower limit process described later. That is, when the first provisional value YR1 is equal to or greater than the second correction value YH2 obtained by correcting the second provisional value YR2, the control device 200 calculates the first provisional value YR1 as the first lower limit value Y1 as it is. On the other hand, when the first provisional value YR1 is smaller than the second correction value YH2, the control device 200 calculates a value equal to or less than the second provisional value YR2 and greater than the first provisional value YR1 as the first lower limit value Y1.

[0046] The control device 200 can execute a second lower limit process for calculating the second lower limit value Y2. In the second lower limit process, each variable used or calculated in the first lower limit process is replaced with a variable for calculating the second lower limit value Y2. That is, the second lower limit process includes a second pre-processing for the lower limit and a second calculation process. In the second pre-processing for the lower limit, the control device 200 calculates the second provisional value YR2 based on the engine speed NE. In the second calculation process for the lower limit, if the second provisional value YR2 is equal to or greater than the first correction value YH1 obtained by correcting the first provisional value YR1, the control device 200 calculates the second provisional value YR2 as it is as the second lower limit value Y2. On the other hand, when the second provisional value YR2 is smaller than the first correction value YH1, the control device 200 calculates a value that is equal to or smaller than the first provisional value YR1 and larger than the second provisional value YR2 as the second lower limit value Y2.

[0047] The control device 200 stores a misfire map in advance as information required in the first lower limit process and the second lower limit process (hereinafter, referred to as required information for the lower limit). Here, the minimum value of the amount of intake air that needs to be introduced into the cylinder group to avoid misfire during the above-mentioned combustion operation in which the mixture is burned is called the first minimum value. The misfire map represents the relationship between the engine speed NE, the EGR rate, and the first minimum value. Note that the misfire map also includes the relationship between the engine speed NE and the first minimum value when the EGR rate is zero. In the misfire map, for example, when the EGR rate is zero, the higher the engine speed NE, the larger the first minimum value becomes. Note that the misfire map is created based on, for example, an experiment or a simulation.

[0048] The control device 200 stores a negative pressure map in advance as necessary information for the lower limit. Here, during the execution of the fuel cut, the opening of the throttle valve is reduced. At this time, the so-called engine brake acts, and the negative pressure downstream of the throttle valve in the intake passage may become large. If this negative pressure becomes excessively large, the lubricating oil in the crankcase is sucked up to the upper side of the piston in the cylinder through the gap between the cylinder and the piston. The sucked up lubricating oil is later burned together with the air-fuel mixture, which leads to a reduction in the lubricating oil available for lubricating the internal combustion engine 100. Regarding the amount of intake air introduced into the cylinder group, the minimum value of the amount of intake air that can prevent the negative pressure in the intake passage from becoming excessively large during the execution of the fuel cut is called the second minimum value. The negative pressure map represents the relationship between the engine rotation speed NE and the second minimum value. In the negative pressure map, basically, the higher the engine rotation speed NE, the larger the second minimum value. The negative pressure map is created based on, for example, an experiment or a simulation.

[0049] The control device 200 prestores a lower limit circuit limit value as necessary information for the lower limit. The lower limit circuit limit value is a limit value that is not considered to be an insufficient value caused by an abnormality in the circuit of the control device 200. The lower limit circuit limit value is calculated based on, for example, an experiment or a simulation.

[0050] The control device 200 prestores a lower limit correction coefficient (hereinafter, referred to as the lower limit coefficient) VD as necessary information for the lower limit. The lower limit coefficient VD is predefined as a value smaller than 1. In this embodiment, the lower limit coefficient VD is 0.8. The lower limit coefficient VD is predefined, for example, by an experiment or a simulation, in consideration of the degree of fluctuation of the engine speed NE, similar to the upper limit coefficient VU. That is, the value obtained by dividing the smaller of the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20 by the larger of the two is called the lower limit specific value. The lower limit coefficient VD is the minimum value of the lower limit specific value that can suppress the time fluctuation of the engine speed NE within an allowable range when the internal combustion engine 100 is in a steady state.

[0051] <Specific Processing Procedures for the First Lower Limit Process and the Second Lower Limit Process> When the engine speed NE is greater than zero, the control device 200 repeatedly executes the first lower limit process. As shown in FIG. 3(a), when the control device 200 starts the first lower limit process, it first executes the process of step S310. In step S310, the control device 200 calculates a first provisional value YR1. Specifically, the control device 200 refers to either the misfire map or the negative pressure map depending on the operating state of the internal combustion engine 100. The control device 200 refers to the misfire map during the execution of the combustion operation. At the same time, the control device 200 refers to the latest engine speed NE and the latest first target EGR rate W1. Then, the control device 200 calculates a first minimum value corresponding to the latest engine speed NE and the latest first target EGR rate W1 in the misfire map. Then, the control device 200 calculates the larger value of the first minimum value and the circuit limit value for the lower limit as the first provisional value YR1. On the other hand, the control device 200 refers to the negative pressure map during the execution of the fuel cut. At the same time, the control device 200 refers to the latest engine speed NE. Then, the control device 200 calculates a second minimum value corresponding to the latest engine speed NE in the negative pressure map. Then, the control device 200 calculates the larger value of this second minimum value and the circuit limit value for the lower limit as a first provisional value YR1. After calculating the first provisional value YR1, the control device 200 proceeds to the process in step S320. The process in step S310 is a first preliminary process for the lower limit.

[0052] In step S320, the control device 200 calculates a second correction value YH2. Specifically, the control device 200 refers to the latest second provisional value YR2 calculated in the second lower limit process. Then, the control device 200 multiplies this second provisional value YR2 by a lower limit coefficient VD. Then, the control device 200 sets the obtained value as the second correction value YH2. After calculating the second correction value YH2, the control device 200 advances the process to step S330.

[0053] In step S330, the control device 200 calculates a first lower limit value Y1. Specifically, the control device 200 sets the larger value of the first provisional value YR1 calculated in step S310 and the second correction value YH2 calculated in step S320 as the first lower limit value Y1. After calculating the first lower limit value Y1, the control device 200 temporarily ends a series of processes for the first lower limit. After this, the control device 200 performs the process of step S310 again. The processes of steps S320 and S330 are the first calculation process for the lower limit.

[0054] When the engine speed NE is greater than zero, the control device 200 repeatedly executes the second lower limit process in parallel with the first lower limit process. That is, as shown in FIG. 3B, the control device 200 first calculates a second provisional value YR2 in step S410. The calculation method of the second provisional value YR2 is the same as the calculation method of the first provisional value YR1, except that the second target EGR rate W2 is used instead of the first target EGR rate W1 used in the first lower limit process. In the following step S420, the control device 200 refers to the latest first provisional value YR1 calculated in the first lower limit process, and sets the value obtained by multiplying the first provisional value YR1 by a lower limit coefficient VD as the first correction value YH1. In the next step S430, the control device 200 sets the larger value of the second provisional value YR2 calculated in step S410 and the first correction value YH1 calculated in step S420 as the second lower limit value Y2. Then, the control device 200 temporarily ends the series of processes for the second lower limit. The process of step S410 is a second preliminary process for the lower limit. The processes of steps S420 and S430 are a second calculation process for the lower limit.

[0055] <Embodiment Action 1: First Upper Limit Processing and Second Upper Limit Processing> A difference may occur between the first temperature T1 and the second temperature T2. This is due to factors such as differences in the arrangement of the intake passages in the engine room of the vehicle 300 and individual differences between the first temperature sensor 62 and the second temperature sensor 72. As described above, the control device 200 uses a setting map including the temperature of the intake air as a parameter in calculating the first provisional value XR1. Therefore, the first provisional value XR1 may be large or small depending on the first temperature T1. Similarly, the second provisional value XR2 may be large or small depending on the second temperature T2. Therefore, in a situation where a difference occurs between the first temperature T1 and the second temperature T2 due to factors such as those described above, a deviation may occur between the first provisional value XR1 and the second provisional value XR2.

[0056] Now, it is assumed that the latest first provisional value XR1 is greater than the latest second provisional value XR2 by a certain percentage or more due to the difference between the first temperature T1 and the second temperature T2. In detail, it is assumed that the first provisional value XR1 is greater than the second correction value XH2 obtained by correcting the second provisional value XR2. In this case, the control device 200 calculates the second correction value XH2 as the first upper limit value X1 in the first upper limit process (step S130). On the other hand, in the second upper limit process, the control device 200 calculates the second provisional value XR2 as the second upper limit value X2 because the second provisional value XR2 is smaller than the first provisional value XR1 (step S230). Here, the second correction value XH2 that is set as the first upper limit value X1 in the first upper limit process has a difference from the second provisional value XR2 that is smaller than the first provisional value XR1. Therefore, compared to the case where the first provisional value XR1 is set to the first upper limit value X1, the difference between the first upper limit value X1 of this embodiment and the second provisional value XR2, that is, the difference between the first upper limit value X1 and the second upper limit value X2, becomes smaller.

[0057] In the above, an example was given in which the first provisional value XR1 is greater than the second provisional value XR2, but also in the case in which the second provisional value XR2 is greater than the first provisional value XR1, the difference between the upper limit values ​​becomes small in the same manner.

[0058] <Embodiment Action 2: First Lower Limit Processing and Second Lower Limit Processing> As described above, the control device 200 uses a misfire map including the engine speed NE and the EGR rate as parameters, or a negative pressure map including the engine speed NE as a parameter, in calculating the first provisional value YR1. Therefore, the first provisional value YR1 changes according to the engine speed NE and the first target EGR rate W1. Similarly, the second provisional value YR2 changes according to the engine speed NE and the second target EGR rate W2. Therefore, for example, when the engine speed NE changes suddenly due to a sudden acceleration or deceleration of the vehicle 300, a deviation may occur between the first provisional value YR1 and the second provisional value YR2 for the following reason. That is, if there is a slight difference in timing when the control device 200 refers to the engine speed NE in calculating each provisional value, the engine speed NE used to calculate the first provisional value YR1 and the engine speed NE used to calculate the second provisional value YR2 will deviate from each other. Accordingly, for example, before and after a sudden change in the engine speed NE, a deviation may occur between the first provisional value YR1 and the second provisional value YR2. Also, as described above, since each provisional value changes depending on the target EGR rate, a deviation may occur between the first provisional value YR1 and the second provisional value YR2 even in a situation where a difference occurs between the first target EGR rate W1 and the second target EGR rate W2.

[0059] Now, for the reasons described above, it is assumed that the latest first provisional value YR1 is smaller than the latest second provisional value YR2 by a certain percentage or more. In detail, it is assumed that the first provisional value YR1 is smaller than the second correction value YH2 obtained by correcting the second provisional value YR2. In this case, the control device 200 calculates the second correction value YH2 as the first lower limit value Y1 in the first lower limit process (step S330). On the other hand, in the second lower limit process, the control device 200 calculates the second provisional value YR2 as the second lower limit value Y2 (step S430) because the second provisional value YR2 is larger than the first provisional value YR1. Here, the difference between the second correction value YH2, which is set as the first lower limit value Y1 in the first lower limit process, and the second provisional value YR2 is smaller than the first provisional value YR1. Therefore, compared to the case where the first provisional value YR1 is set as the first lower limit value Y1, the difference between the first lower limit value Y1 of this embodiment and the second provisional value YR2, that is, the difference between the first lower limit value Y1 and the second lower limit value Y2, is smaller.

[0060] In the above, an example has been given in which the first provisional value YR1 is smaller than the second provisional value YR2, but even if the second provisional value YR2 is smaller than the first provisional value YR1, the difference between the lower limit values ​​becomes small in a similar manner.

[0061] <Effects of the embodiment> (1) As described above, if there is a difference between the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20, a difference in the amount of piston movement may occur between the first cylinder group 10 and the second cylinder group 20. If the difference in the amount of movement is large, the following concerns may arise. That is, the internal combustion engine 100 may vibrate, which may deteriorate the ride comfort of the occupants of the vehicle 300. In addition, the time fluctuation of the engine speed NE when the internal combustion engine 100 is in a steady state may become large, which may lead to an erroneous determination that a misfire has occurred.

[0062] In this regard, by performing the above-mentioned first upper limit process and second upper limit process, the following is possible. That is, in a situation where the difference between the first upper limit value X1, which is the upper limit of the amount of intake air introduced into the first cylinder group 10, and the second upper limit value X2, which is the upper limit of the amount of intake air introduced into the second cylinder group 20, becomes large, each upper limit value can be calculated so that the difference between the two becomes small. Furthermore, in calculating each upper limit value, the smaller of the provisional value and the correction value is selected. In this case, the value obtained by dividing the larger of the first upper limit value X1 and the second upper limit value X2 by the smaller of the two becomes equal to or smaller than the upper limit coefficient VU used in calculating each correction value. That is, the ratio of the first upper limit value X1 and the second upper limit value X2 can be made closer to 1 than the ratio represented by the upper limit coefficient VU. Therefore, it is possible to suppress the deviation between the first upper limit value X1 and the second upper limit value X2, and thus the increase in the difference between the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20.

[0063] (2) As described above, the first lower limit process and the second lower limit process can perform the following. That is, in a situation where the difference between the first lower limit value Y1, which is the lower limit of the amount of intake air introduced into the first cylinder group 10, and the second lower limit value Y2, which is the lower limit of the amount of intake air introduced into the second cylinder group 20, becomes large, each lower limit value can be calculated so that the difference between the two is small. Furthermore, in calculating each lower limit value, the larger of the provisional value and the correction value is selected. In this case, the value obtained by dividing the smaller of the first lower limit value Y1 and the second lower limit value Y2 by the larger of the two is equal to or larger than the lower limit coefficient VU used in calculating each correction value. That is, the ratio of the first lower limit value Y1 and the second lower limit value Y2 can be made closer to 1 than the ratio represented by the lower limit coefficient VD. Therefore, the deviation between the first lower limit value Y1 and the second lower limit value Y2, and therefore the difference between the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20, can be suppressed from becoming large.

[0064] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0065] The upper limit coefficient VU is not limited to the example of the above embodiment. The upper limit coefficient VU may be set so that the difference between the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20 can be within an appropriate range. The upper limit coefficient VU may be a value greater than 1. The upper limit coefficient VU may be changed according to the operating state of the internal combustion engine 100. For example, the upper limit coefficient VU may be changed during so-called idling operation in which the internal combustion engine 100 operates at the minimum engine speed NE at which it can continue to operate independently, and during normal operation. In addition, the upper limit coefficient VU used when calculating the first correction value XH1 and the upper limit coefficient VU used when calculating the second correction value XH2 may be different values. When it is known in advance that there is a difference between the amount of intake air introduced into the first cylinder group 10 and the amount of intake air introduced into the second cylinder group 20 due to a difference in the arrangement of the first intake passage 11 and the second intake passage 21, such an embodiment is also effective.

[0066] As in the above modified example, the lower limit coefficient VD is not limited to the example in the above embodiment. The lower limit coefficient VD may be a value smaller than 1. As in the upper limit coefficient VU, the lower limit coefficient VD may be changed according to the operating state of the internal combustion engine 100, or different lower limit coefficients VD may be set for calculating the first correction value YH1 and the second correction value YH2.

[0067] The calculation method of the first provisional value XR1 in the first pre-processing for the upper limit is not limited to the example of the above embodiment. The first provisional value XR1 may be calculated based on the first temperature T1 detected by the first temperature sensor 62. For example, the maximum introduction value at the standard atmospheric pressure and the reference intake temperature may be stored in advance as a basic maximum value, and the final value of the maximum introduction value may be calculated by correcting the basic maximum value according to the magnitude of the first temperature T1 and the atmospheric pressure P. Then, the final value may be compared with a protection limit value or the like to calculate the first provisional value XR1.

[0068] As in the above modification, the method of calculating the second provisional value XR2 in the second pre-processing for the upper limit is not limited to the example in the above embodiment. The second provisional value XR2 may be calculated based on the second temperature T2 detected by the second temperature sensor 72.

[0069] The calculation method of the first upper limit value X1 in the first calculation process for the upper limit is not limited to the example of the above embodiment. That is, it is not essential to use a method of selecting the smaller value of the first provisional value XR1 and the second correction value XH2 when calculating the first upper limit value X1. The calculation method of the first upper limit value X1 may be any method that satisfies the following. When the first provisional value XR1 is equal to or smaller than the second correction value XH2, the first provisional value XR1 is calculated as the first upper limit value X1 as it is. When the first provisional value XR1 is greater than the second correction value XH2, a value equal to or larger than the second provisional value XR2 and smaller than the first provisional value XR1 is calculated as the first upper limit value X1. For example, when the first provisional value XR1 is greater than the second correction value XH2, the second provisional value XR2 may be calculated as the first upper limit value X1. In the above case, the middle value between the first provisional value XR1 and the second provisional value XR2 may be calculated as the first upper limit value X1.

[0070] As in the above modified example, the calculation method of the second upper limit value X2 in the second calculation process for the upper limit is not limited to the example of the above embodiment. The calculation method of the second upper limit value X2 may be any method that satisfies the following: If the second provisional value XR2 is equal to or less than the first correction value XH1, the second provisional value XR2 is calculated as the second upper limit value X2 as is. If the second provisional value XR2 is greater than the first correction value XH1, a value equal to or greater than the first provisional value XR1 and less than the second provisional value XR2 is calculated as the second upper limit value X2.

[0071] The calculation method of the first provisional value YR1 in the first preliminary process for the lower limit is not limited to the example of the above embodiment. The first provisional value YR1 may be calculated based on the engine speed NE. For example, as in a modified example described later, when the first EGR passage 16 is eliminated, the first provisional value YR1 may be calculated without considering the first target EGR rate W1.

[0072] As in the above modified example, the method of calculating the second provisional value YR2 in the second pre-processing for the lower limit is not limited to the example in the above embodiment. The second provisional value YR2 may be calculated based on the engine speed NE.

[0073] The calculation method of the first lower limit value Y1 in the first calculation process for the lower limit is not limited to the example of the above embodiment. That is, it is not essential to use a method of selecting the larger value of the first provisional value YR1 and the second correction value YH2 when calculating the first lower limit value Y1. The calculation method of the first lower limit value Y1 may be any method that satisfies the following. When the first provisional value YR1 is equal to or greater than the second correction value YH2, the first provisional value YR1 is calculated as the first lower limit value Y1 as is. When the first provisional value YR1 is smaller than the second correction value YH2, a value equal to or less than the second provisional value YR2 and larger than the first provisional value YR1 is calculated as the first lower limit value Y1. For example, when the first provisional value YR1 is smaller than the second correction value YH2, the second provisional value YR2 may be calculated as the first lower limit value Y1. In the above case, the middle value between the first provisional value YR1 and the second provisional value YR2 may be calculated as the first lower limit value Y1.

[0074] As in the above modified example, the calculation method of the second lower limit value Y2 in the second calculation process for the lower limit is not limited to the example of the above embodiment. The calculation method of the second lower limit value Y2 may be any method that satisfies the following: If the second provisional value YR2 is equal to or greater than the first correction value YH1, the second provisional value YR2 is calculated as the second lower limit value Y2 as is. If the second provisional value YR2 is smaller than the first correction value YH1, a value equal to or less than the first provisional value YR1 and greater than the second provisional value YR2 is calculated as the second lower limit value Y2.

[0075] The overall configuration of the internal combustion engine 100 is not limited to the example of the above embodiment. For example, the number of cylinders in the cylinder group may be changed. The installation position of the temperature sensor may be changed. For example, the temperature sensor may be disposed downstream of the intercooler in the intake passage. If the installation position of the temperature sensor is changed, a setting map may be created for that installation position. Both or either one of the first EGR passage 16 and the second EGR passage 26 may be eliminated. In other words, the first bank portion 110 and the second bank portion 120 may not be completely symmetrical. The internal combustion engine 100 may have the first cylinder group 10, the first intake passage 11 that introduces intake air to the first cylinder group 10, and the first throttle valve 15 that adjusts the amount of intake air introduced to the first cylinder group 10. Moreover, it is sufficient that the internal combustion engine 100 has the second cylinder group 20, a second intake passage 21 that introduces intake air to the second cylinder group 20, and a second throttle valve 25 that adjusts the amount of intake air introduced to the second cylinder group 20. From the viewpoint of calculating the first upper limit value X1 and the second upper limit value X2 only, the crank position sensor 93 is not essential. From the viewpoint of calculating the first lower limit value Y1 and the second lower limit value Y2 only, the first temperature sensor 62 and the second temperature sensor 72 are not essential. [Explanation of symbols]

[0076] 10…1st cylinder group 10A…Cylinder 11…First intake passage 15…First throttle valve 20…Second cylinder group 20A…Cylinder 21…Second intake passage 25…Second throttle valve 62…First temperature sensor 72…Second temperature sensor 93...Crank position sensor 100…Internal combustion engine 130…Crankshaft 200...Control device

Claims

1. A first cylinder group; a first intake passage that introduces intake air into the first cylinder group; a first throttle valve that adjusts the amount of intake air introduced into the first cylinder group; a first temperature sensor that detects a temperature of the intake air flowing through the first intake passage; a second cylinder group consisting of cylinders different from the first cylinder group; a second intake passage that introduces intake air into the second cylinder group; a second throttle valve that adjusts the amount of intake air introduced into the second cylinder bank; a second temperature sensor that detects a temperature of the intake air flowing through the second intake passage; The present invention is applied to an internal combustion engine having a first control process for calculating a first target value that is a target value of an amount of intake air to be introduced into the first cylinder group, and for controlling the first throttle valve based on the first target value; a second control process for calculating a second target value that is a target value of the amount of intake air to be introduced into the second cylinder bank, and controlling the second throttle valve based on the second target value; a first preliminary process of calculating a first provisional value as a provisional value of a first upper limit value that is an upper limit value of the first target value based on a temperature detected by the first temperature sensor; a second pre-processing for calculating a second provisional value as a provisional value of a second upper limit value that is an upper limit value of the second target value based on the temperature detected by the second temperature sensor; a first calculation process for calculating, when the first provisional value is equal to or less than a second correction value obtained by multiplying the second provisional value by a correction coefficient that is predetermined as a value greater than 1, the first provisional value as the first upper limit value, and for calculating, when the first provisional value is greater than the second correction value, a value that is equal to or more than the second provisional value and less than the first provisional value as the first upper limit value; a second calculation process for calculating, when the second provisional value is equal to or less than a first correction value obtained by multiplying the first provisional value by the correction coefficient, the second provisional value as the second upper limit value, and for calculating, when the second provisional value is greater than the first correction value, a value equal to or greater than the first provisional value and less than the second provisional value as the second upper limit value; A control device for an internal combustion engine capable of executing the above.

2. In the first calculation process, a smaller value of the first provisional value and the second correction value is calculated as the first upper limit value; In the second calculation process, a smaller value of the second provisional value and the first correction value is calculated as the second upper limit value. The control device for an internal combustion engine according to claim 1.

3. A first cylinder group; a first intake passage that introduces intake air into the first cylinder group; a first throttle valve that adjusts the amount of intake air introduced into the first cylinder group; a second cylinder group consisting of cylinders different from the first cylinder group; a second intake passage that introduces intake air into the second cylinder group; a second throttle valve that adjusts the amount of intake air introduced into the second cylinder bank; A crank position sensor that detects the rotational position of a crankshaft; The present invention is applied to an internal combustion engine having a first control process for calculating a first target value that is a target value of an amount of intake air to be introduced into the first cylinder group, and for controlling the first throttle valve based on the first target value; a second control process for calculating a second target value that is a target value of the amount of intake air to be introduced into the second cylinder bank, and controlling the second throttle valve based on the second target value; a first preliminary process of calculating a first provisional value as a provisional value of a first lower limit value that is a lower limit value of the first target value based on a rotation speed of the crankshaft; a second preliminary process of calculating a second provisional value as a provisional value of a second lower limit value that is a lower limit value of the second target value based on a rotation speed of the crankshaft; a first calculation process for calculating, when the first provisional value is equal to or greater than a second correction value obtained by multiplying the second provisional value by a correction coefficient that is a predetermined value smaller than 1, the first provisional value as the first lower limit value, and for calculating, when the first provisional value is smaller than the second correction value, a value that is equal to or less than the second provisional value and larger than the first provisional value as the first lower limit value; a second calculation process for calculating, when the second provisional value is equal to or greater than a first correction value obtained by multiplying the first provisional value by the correction coefficient, the second provisional value as the second lower limit value, and for calculating, when the second provisional value is smaller than the first correction value, a value equal to or less than the first provisional value and greater than the second provisional value as the second lower limit value; A control device for an internal combustion engine capable of executing the above.

4. In the first calculation process, a larger value of the first provisional value and the second correction value is calculated as the first lower limit value; In the second calculation process, a larger value of the second provisional value and the first correction value is calculated as the second lower limit value. The control device for an internal combustion engine according to claim 3.

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