Control device of internal combustion engine and program for internal combustion engine

Abstract

To equalize the amount of water to be introduced to each cylinder.SOLUTION: An internal combustion engine 10 includes a plurality of cylinders 12, a water injection valve 60 for each cylinder 12, an EGR passage 50 for introducing a portion of exhaust flowing in an exhaust passage 30 to an intake passage 20, and an EGR cooler 52 provided in the course of the EGR passage 50. When an amount of condensed water flowing into one cylinder 12 for a unit period in condensed water caused in the EGR passage 50 is regarded as an EGR water amount, a memory 92 stores information representing a correspondence relation between a parameter about an operational state of the internal combustion engine 10 and a parameter about the EGR water amount for each cylinder 12. A CPU 91 executes processing for acquiring a value obtained by subtracting the EGR water amount of each cylinder 12 from a basic water amount corresponding to the operational state of the internal combustion engine 10 as a target water injection amount of each cylinder 12, and processing for controlling respective water injection valves 60 so as to inject the target water injection amount of each cylinder 12 on the basis of the information for operation of the internal combustion engine 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] The internal combustion engine disclosed in Patent Document 1 is equipped with an EGR passage. The EGR passage extends from an exhaust passage to an intake passage. The EGR passage introduces a portion of the exhaust gas flowing through the exhaust passage into the intake passage as EGR gas. The internal combustion engine is also equipped with a water injection valve. A water injection valve is provided for each cylinder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-168929 Summary of the Invention [Problem to be solved by the invention]

[0004] In an internal combustion engine such as that described in Patent Document 1, which is equipped with an EGR passage and a water injection valve, an EGR cooler for cooling EGR gas is sometimes provided in the EGR passage. In such a configuration, moisture contained in the EGR gas condenses in the EGR passage. This condensed water flows into each cylinder via the intake passage along with the EGR gas. The amount of condensed water flowing into each cylinder may vary from cylinder to cylinder due to various factors, such as the gas flow pattern to each cylinder due to the shape of the intake passage. If the same amount of water is injected from each water injection valve under conditions in which the amount of condensed water flowing into each cylinder differs, the total amount of water reaching each cylinder may differ from cylinder to cylinder. This may result in variations in combustion conditions between cylinders. [Means for solving the problem]

[0005] The control device for an internal combustion engine for solving the above-mentioned problems is applied to an internal combustion engine including an engine body into which a plurality of cylinders are partitioned, a water injection valve for each of the cylinders for supplying water to each of the cylinders, an EGR passage for introducing a portion of exhaust gas flowing through an exhaust passage into an intake passage as EGR gas, and an EGR cooler provided midway through the EGR passage for cooling the EGR gas, and the control device includes an execution unit and a memory unit, and calculates the amount of condensed water generated in the EGR passage that flows into one of the cylinders in a unit period as an EGR water amount. When this is done, the memory unit stores information that represents the correspondence between operating parameters related to the operating state of the internal combustion engine and water quantity parameters related to the EGR water quantity for each cylinder, and the execution unit executes, based on the information, a first process of obtaining a value obtained by subtracting the EGR water quantity for each cylinder from a basic water quantity corresponding to the operating state of the internal combustion engine as a target water injection quantity for each cylinder, and a second process of controlling each water injection valve to inject the target water injection quantity for each cylinder.

[0006] A program for an internal combustion engine to solve the above problem is a control device applied to an internal combustion engine having an engine body divided into multiple cylinders, a water injection valve for each of the cylinders to supply water to each of the cylinders, an EGR passage that introduces a portion of the exhaust gas flowing through the exhaust passage into an intake passage as EGR gas, and an EGR cooler provided in the EGR passage to cool the EGR gas.When the amount of condensed water generated in the EGR passage that flows into one of the cylinders in a unit period is defined as the EGR water amount, the control device stores information representing, for each of the cylinders, a correspondence between operating parameters related to the operating state of the internal combustion engine and water amount parameters related to the EGR water amount.During operation of the internal combustion engine, based on the information, the control device obtains, as a target water injection amount for each of the cylinders, a value obtained by subtracting the EGR water amount for each of the cylinders from a basic water amount corresponding to the operating state of the internal combustion engine, and a second process that controls each of the water injection valves to inject the target water injection amount for each of the cylinders. [Effects of the Invention]

[0007] Each of the above technical concepts allows the amount of water introduced into each cylinder to be uniform. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an internal combustion engine. [Figure 2] FIG. 2 is a diagram showing a schematic representation of water volume information. [Figure 3] FIG. 3 is a flowchart showing the processing contents of the water injection control. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment A first embodiment of a control device for an internal combustion engine will be described below with reference to the drawings. As shown in FIG. 1, a vehicle 200 is equipped with an internal combustion engine 10. The internal combustion engine 10 is a drive source for the vehicle 200. The internal combustion engine 10 is equipped with an engine body 10A and a crankshaft 11. The engine body 10A is equipped with a plurality of cylinders 12. There are four cylinders 12. The cylinders 12 are spaces defined in the engine body 10A. The cylinders 12 are spaces for burning a mixture of intake air and fuel. Although not shown, each cylinder 12 houses a piston. The piston reciprocates within the cylinder 12 in response to the combustion of the mixture. The crankshaft 11 rotates in response to the reciprocating movement of the piston.

[0010] The internal combustion engine 10 includes a plurality of spark plugs 13 and a plurality of fuel injection valves 14. One spark plug 13 is provided for each cylinder 12. The spark plug 13 ignites the air-fuel mixture in the cylinder 12 by spark discharge. Another fuel injection valve 14 is provided for each cylinder 12. The fuel injection valve 14 of this embodiment injects fuel directly into the cylinder 12 without passing through an intake passage 20, which will be described later. The fuel injection valve 14 injects hydrogen gas as fuel.

[0011] The internal combustion engine 10 has an intake passage 20. The intake passage 20 is a passage for introducing intake air into each cylinder 12. The intake passage 20 has an upstream passage 21 and a plurality of branch passages 22. The upstream passage 21 is connected to each cylinder 12 via the branch passages 22. A branch passage 22 is provided for each cylinder 12. The branch passage 22 is connected to the downstream end of the upstream passage 21. The branch passage 22 then leads to the corresponding cylinder 12. In other words, the plurality of branch passages 22 branch off to each cylinder 12 at the downstream end of the upstream passage 21.

[0012] The internal combustion engine 10 is equipped with an intercooler 23 and a throttle valve 25. The throttle valve 25 is located midway through the upstream passage 21. The opening of the throttle valve 25 is adjustable. The intake air amount GA changes depending on the opening of the throttle valve 25. The intercooler 23 is located upstream of the throttle valve 25 in the upstream passage 21. The intercooler 23 cools the inside of the upstream passage 21. In FIG. 1, the flow of gas in each passage is indicated by arrows.

[0013] The internal combustion engine 10 is equipped with a plurality of water injectors 60. One water injector 60 is provided for each cylinder 12. The water injectors 60 inject water into the cylinders 12 via the branch passages 22. That is, each water injector 60 supplies water to its respective cylinder 12.

[0014] The internal combustion engine 10 includes an exhaust passage 30. The exhaust passage 30 is a passage for discharging exhaust gas from each cylinder 12. The exhaust passage 30 is connected to each cylinder 12. The internal combustion engine 10 includes a turbocharger 40. The turbocharger 40 is provided across the intake passage 20 and the exhaust passage 30. The turbocharger 40 includes a compressor wheel 41, a turbine wheel 42, a bypass passage 43, and a WG valve 44. The compressor wheel 41 is located upstream of the intercooler 23 in the upstream passage 21. The turbine wheel 42 is located midway through the exhaust passage 30. The turbine wheel 42 rotates in accordance with the flow of exhaust gas. The compressor wheel 41 rotates integrally with the turbine wheel 42. When the compressor wheel 41 rotates, the compressor wheel 41 compresses and sends out intake air. That is, the compressor wheel 41 supercharges the intake air flowing through the upstream passage 21. The bypass passage 43 connects an upstream portion of the exhaust passage 30 with a downstream portion of the turbine wheel 42. That is, the bypass passage 43 is a passage that bypasses the turbine wheel 42. The WG valve 44 is located midway through the bypass passage 43. The opening of the WG valve 44 is adjustable. As the opening of the WG valve 44 decreases, the amount of exhaust gas flowing through the bypass passage 43 decreases. At the same time, the amount of exhaust gas passing through the turbine wheel 42 increases. As a result, the rotational speeds of the turbine wheel 42 and the compressor wheel 41 increase. This increases the boost pressure.

[0015] The internal combustion engine 10 includes an EGR passage 50, an EGR cooler 52, and an EGR valve 54. The EGR passage 50 connects a portion of the exhaust passage 30 downstream of the turbine wheel 42 with a portion of the intake passage 20 between the compressor wheel 41 and the intercooler 23. The EGR passage 50 is a passage for introducing a portion of the exhaust gas flowing through the exhaust passage 30 into the intake passage 20 as EGR gas. The EGR cooler 52 is located midway through the EGR passage 50. The EGR cooler 52 cools the EGR gas flowing through the EGR passage 50. The EGR valve 54 is located on the intake passage 20 side of the EGR cooler 52 in the EGR passage 50. The opening degree of the EGR valve 54 is adjustable. The amount of EGR gas flowing through the EGR passage 50 changes depending on the opening degree of the EGR valve 54.

[0016] The internal combustion engine 10 is equipped with a plurality of sensors. For example, the internal combustion engine 10 is equipped with a crank position sensor 81 and an air flow meter 82. The crank position sensor 81 is located near the crankshaft 11. The crank position sensor 81 detects the rotational position CR of the crankshaft 11. The air flow meter 82 is located in the intake passage 20 upstream of the compressor wheel 41. The air flow meter 82 detects the intake air amount GA. The vehicle 200 is also equipped with an accelerator sensor 83 and a vehicle speed sensor 84. The accelerator sensor 83 detects the depression amount of an accelerator pedal of the vehicle 200 as an accelerator operation amount AC. The vehicle speed sensor 84 detects the traveling speed of the vehicle 200 as a vehicle speed SP. Each of these sensors repeatedly transmits a signal corresponding to the information detected by itself to a control device 90, which will be described later.

[0017] <Outline of the control device> The vehicle 200 includes a control device 90. The control device 90 includes a CPU 91 and a memory 92. The CPU 91 is an execution unit. The memory 92 includes three types of memory: a RAM, a ROM, and an electrically rewritable non-volatile memory. In this embodiment, these three types of storage media are collectively referred to as the memory 92. The memory 92 is a storage unit. The memory 92 pre-stores various programs W for the internal combustion engine 10, in which processes to be executed by the CPU 91 are described, and various data required for the CPU 91 to execute the programs W. The CPU 91 controls the internal combustion engine 10. The CPU 91 controls various parts of the internal combustion engine 10 by executing the programs W. An example of the various data stored in the memory 92 is identification information for distinguishing between the multiple cylinders 12. In this embodiment, a cylinder number pre-assigned to each cylinder 12 is used as an example of the identification information. That is, the four cylinders 12 are assigned values ​​of "1" to "4" in order.

[0018] The CPU 91 repeatedly receives detection signals from various sensors attached to the vehicle 200 while the ignition switch of the vehicle 200 is on. Based on the received detection signals, the CPU 91 calculates various parameters required for controlling the internal combustion engine 10 as needed. For example, the CPU 91 calculates an engine speed NE, which is the rotational speed of the crankshaft 11, based on the rotational position CR of the crankshaft 11. The CPU 91 also calculates an engine load factor KL based on the engine speed NE and the intake air amount GA. The engine load factor KL is a parameter that determines the amount of air charged into the cylinders 12. More specifically, the engine load factor KL is a value obtained by dividing the amount of air flowing into one cylinder 12 per combustion cycle by a reference air amount. The reference air amount varies depending on the engine speed NE. One combustion cycle is a series of periods in which one cylinder 12 undergoes one intake stroke, one compression stroke, one expansion stroke, and one exhaust stroke.

[0019] The CPU 91 performs the following process when controlling the internal combustion engine 10. While the ignition switch of the vehicle 200 is on, the CPU 91 repeatedly calculates a target torque for the internal combustion engine 10 based on the accelerator operation amount AC, the vehicle speed SP, and the like. Then, the CPU 91 controls the throttle valve 25, the fuel injection valve 14, and the spark plug 13 so as to obtain the latest target torque. That is, the CPU 91 adjusts the opening of the throttle valve 25, the amount of fuel injected from the fuel injection valve 14, and the ignition timing of the spark plug 13. Through these controls, the CPU 91 repeatedly combusts the air-fuel mixture in each cylinder 12. That is, the CPU 91 operates the internal combustion engine 10. When operating the internal combustion engine 10, the CPU 91 also adjusts the opening of the WG valve 44 and the opening of the EGR valve 54 based on the target torque, the engine rotation speed NE, the engine load factor KL, and the like.

[0020] <Water amount information> In the EGR passage 50, the EGR gas is cooled by an EGR cooler 52 located midway through the passage. Accordingly, moisture contained in the EGR gas condenses in the EGR passage 50. Hereinafter, the amount of condensed water generated in the EGR passage 50 that flows into one cylinder 12 in a predetermined unit period is referred to as an EGR water amount Q. In this embodiment, the unit period is one combustion cycle.

[0021] As shown in FIG. 1, the memory 92 stores water amount information M in advance. As shown in FIG. 2, the water amount information M is information that represents the correspondence between operating parameters and water amount parameters for each cylinder 12. The operating parameters are parameters related to the operating state of the internal combustion engine 10. The water amount parameter is a parameter related to the EGR water amount Q. Specific details of these operating parameters and water amount parameters will be described later. Hereinafter, information that represents the above correspondence for one cylinder 12 will be referred to as an individual map MX. In other words, the water amount information M is a group of individual maps MX for each of the four cylinders 12. Each individual map MX is assigned the cylinder number of the corresponding cylinder 12.

[0022] The individual map MX will be described in detail. In this embodiment, the operating parameters that define the individual map MX are the engine speed NE and the engine load factor KL. Furthermore, in this embodiment, the water amount parameter that defines the individual map MX is the EGR water amount Q. That is, as shown in FIG. 2 , the individual map MX represents the EGR water amount Q for each combination of the engine speed NE and the engine load factor KL in an orthogonal coordinate system with the engine speed NE as the X-axis and the engine load factor KL as the Y-axis. The individual map MX was created by conducting experiments or simulations on the internal combustion engine 10 having the specifications described in FIG. 1 , operating the internal combustion engine 10 under various operating conditions. As can be seen from the specifications of the internal combustion engine 10, the experiments or simulations for creating the individual map MX were performed on the assumption that the fuel injected by each fuel injection valve 14 is hydrogen gas. The individual map MX and the water amount information M represent the correspondence between the engine speed NE, the engine load factor KL, and the EGR water amount Q when the fuel of the internal combustion engine 10 is hydrogen gas. The experiments or simulations for creating the individual map MX were performed on the assumption that the internal combustion engine 10 is equipped with a turbocharger 40. The content of the operating region in which the turbocharger 40 operates, of the individual map MX and the water amount information M, represents the correspondence between the engine speed NE, the engine load factor KL, and the EGR water amount Q when the turbocharger 40 is operating. The experiments or simulations for creating the individual map MX include fluid analysis using so-called computational fluid dynamics (CFD). In the experiments or simulations for creating the individual map MX, the dynamics of various factors related to the EGR water amount Q are analyzed for each operating state of the internal combustion engine 10. An example of the various factors is the temperature of the gas flowing through various passages of the internal combustion engine 10, such as the intake passage 20, the exhaust passage 30, and the EGR passage 50. An example of the various factors is the amount of moisture contained in the gas flowing through various passages of the internal combustion engine 10. An example of the various factors is the way the gas flows to each cylinder 12 according to the branch shape from the upstream passage 21 to each branch passage 22. The individual map MX reflects these various factors.

[0023] As shown in FIG. 1 , the memory 92 pre-stores basic information B. The basic information B is information that represents the correspondence between operating parameters and basic water amounts. As described above, the operating parameters are the engine speed NE and the engine load factor KL. The basic water amount is the total amount of water that needs to be introduced into one cylinder 12 in the above-mentioned unit period for a specific engine operating state. The basic information B represents the basic water amount for each combination of the engine speed NE and the engine load factor KL in an orthogonal coordinate system with the engine speed NE as the X-axis and the engine load factor KL as the Y-axis. Like the water amount information M, the basic information B is created by conducting experiments or simulations on the internal combustion engine 10 having the specifications described in FIG. 1 .

[0024] <Water injection control> The CPU 91 controls the water injection valve 60. By executing the program W, the CPU 91 can perform water injection control for controlling the water injection valve 60. The CPU 91 repeatedly executes the water injection control described below while the internal combustion engine 10 is operating, that is, from when the ignition switch of the vehicle 200 is turned on until it is turned off.

[0025] As shown in FIG. 3, when the CPU 91 starts water injection control, it first executes the processing of step S10. In step S10, the CPU 91 acquires a target water injection amount for each cylinder 12. For a given cylinder 12, the CPU 91 acquires the target water injection amount as follows: First, the CPU 91 calculates a current basic water amount, which is a basic water amount corresponding to the current operating state of the internal combustion engine 10. Specifically, the CPU 91 reads basic information B from the memory 92. Then, based on the basic information B, the CPU 91 calculates a basic water amount corresponding to the current engine rotation speed NE and engine load factor KL as the current basic water amount. Next, the CPU 91 calculates a current individual water amount, which is the current EGR water amount Q for the target cylinder 12. Specifically, the CPU 91 reads an individual map MX for the target cylinder 12 from the water amount information M from the memory 92. Then, based on the individual map MX read from the memory 92, the CPU 91 calculates the EGR water amount Q corresponding to the current engine rotation speed NE and engine load factor KL as the current individual water amount. After that, the CPU 91 calculates the target water injection amount by subtracting the current individual water amount from the current basic water amount. In this manner, the CPU 91 calculates the target water injection amount for each cylinder 12. The CPU 91 calculating the target water injection amount corresponds to the CPU 91 obtaining the target water injection amount. That is, in step S10, the CPU 91 obtains the target water injection amount for each cylinder 12 based on the basic information B and the water amount information M. After obtaining the target water injection amount for each cylinder 12, the CPU 91 proceeds to step S20. The processing in step S10 is the first processing.

[0026] In step S20, the CPU 91 controls the water injector 60 for each cylinder 12 based on the target water injection amount for each cylinder 12 acquired in step S10. One cylinder 12 is referred to as the target cylinder. The CPU 91 can execute a supply process for the target cylinder. The supply process is a process for causing the water injector 60 of the target cylinder to inject the target water injection amount for the target cylinder within one combustion cycle, which is a unit period. In step S20, the CPU 91 repeats the supply process for each cylinder 12. The CPU 91 continues to repeat the supply process over a predetermined control period. That is, during the control period, the CPU 91 controls each water injector 60 so that each water injector 60 injects the target water injection amount for each cylinder 12 for each unit period. The process of step S20 is the second process. The control period is longer than the time required for one combustion cycle when the internal combustion engine 10 is at the minimum engine speed NE at which it can continue to operate autonomously, i.e., when the internal combustion engine 10 is idling. That is, the control period is longer than the unit period. When the control period has elapsed since the start of step S20, the CPU 91 ends the processing of step S20. The CPU 91 then temporarily ends the series of processes for the water injection control. Thereafter, the CPU 91 promptly starts the processing of step S10. That is, the CPU 91 executes the water injection control again.

[0027] <Operation of the First Embodiment> Condensed water generated in the EGR passage 50 flows into the intake passage 20 together with EGR gas. The condensed water then flows from the upstream passage 21 through the branch passages 22 into each cylinder 12. The amount of condensed water flowing into each cylinder 12 may differ for each cylinder 12 due to factors such as the gas flow pattern depending on the branching shape from the upstream passage 21 to each branch passage 22. In this embodiment, an individual map MX for each cylinder 12 is created in advance to inject water from each water injector 60 while taking into account such differences in the EGR water amount Q for each cylinder 12. The CPU 91 then uses information from the individual map MX for each cylinder 12 to calculate the target water injection amount for each cylinder 12 during water injection control. Specifically, the CPU 91 subtracts the EGR water amount Q obtained from the individual map MX for each cylinder 12 from the basic water amount to calculate the target water injection amount for each cylinder 12. The resulting value corresponds to the portion of the basic water amount that cannot be covered by the EGR water amount Q alone in each cylinder 12. The CPU 91 sets this value as the target water injection amount for each cylinder 12 and causes each water injector 60 to inject water. By introducing water from this water injector 60 and the EGR water amount Q into each cylinder 12, the total amount of water introduced into each cylinder 12 becomes approximately the basic water amount. In other words, an approximately uniform amount of water is introduced into each cylinder 12.

[0028] <Effects of the first embodiment> (1) As described above in the operation of the first embodiment, according to the configuration of this embodiment, a substantially uniform amount of water is introduced into each cylinder 12. Therefore, it is possible to suppress variations in the combustion state among the cylinders 12.

[0029] When setting the target water injection amount for each cylinder 12, it is possible to set a basic water amount, which is a value common to all cylinders 12, to the following value in advance. That is, the basic water amount is set in advance to a value that anticipates that a uniform EGR water amount Q will flow into each cylinder 12. Then, this basic water amount is set directly as the target water injection amount for each cylinder 12. When adopting this embodiment, in order to avoid a shortage of water introduced into each cylinder 12, the anticipated EGR water amount Q can be set to the minimum value that will flow into one cylinder 12 depending on the operating state of the internal combustion engine 10. At the same time, the basic water amount can be set to a larger value. Here, as described above, the EGR water amount Q that actually flows into each cylinder 12 varies. Furthermore, depending on the cylinder 12, the EGR water amount Q may be significantly larger than the anticipated amount. If each water injector 60 were to inject a basic amount of water based on the expected EGR water amount Q into such a cylinder 12, more water than necessary would be introduced into that cylinder 12. In other words, for this cylinder 12, the water injector 60 would inject more water than the shortfall in the EGR water amount Q relative to the amount of water that is actually required. As a result, the amount of water consumed by the water injector 60 would increase. In this regard, with the configuration of this embodiment, only the amount of basic water that cannot be covered by the EGR water amount Q alone is injected from each water injector 60. Therefore, the amount of water injected from each water injector 60 can be minimized.

[0030] (2) In an internal combustion engine 10 fueled by hydrogen gas, the amount of condensed water generated in the EGR passage 50 is greater than in an internal combustion engine fueled by, for example, gasoline. To reflect this in the individual map MX, the individual map MX was created based on experiments or simulations assuming that the fuel of the internal combustion engine 10 is hydrogen gas. In other words, the individual map MX takes into account the fact that the EGR water amount Q increases as hydrogen gas is used as fuel. When the target water injection amount is calculated using such an individual map MX, the target water injection amount can be calculated taking into account the fact that the EGR water amount Q is large, and therefore the target water injection amount is reduced accordingly. Therefore, the amount of water injected from each water injection valve 60 can be reduced.

[0031] (3) When the turbocharger 40 is operating, gas is compressed in the intake passage 20, and the amount of EGR water Q contained per unit volume of the gas increases. In order to reflect this in the individual map MX, the individual map MX is created based on experiments or simulations assuming that the internal combustion engine 10 is equipped with the turbocharger 40. That is, the content of the operating region of the individual map MX in which the turbocharger 40 operates takes into consideration that the EGR water amount Q increases as the turbocharger 40 operates. When the target water injection amount is calculated using such an individual map MX, the target water injection amount can be calculated taking into consideration that the EGR water amount Q is large when the turbocharger 40 is operating, and therefore the target water injection amount is reduced accordingly. Therefore, the amount of water injected from each water injection valve 60 can be reduced.

[0032] Second Embodiment A second embodiment of a control device for an internal combustion engine will be described. The second embodiment differs from the first embodiment only in the water volume information and the processing content of step S10 related thereto. Therefore, the following mainly describes the water volume information and the processing content of step S10 according to the second embodiment, and descriptions of content that overlaps with the first embodiment will be omitted or omitted as appropriate.

[0033] With respect to a specific engine operating state during operation of the internal combustion engine 10, the value obtained by subtracting the EGR water amount Q from the basic water amount is referred to as the required water amount U. The water amount parameter in the second embodiment is the required water amount U. That is, the individual map MX in the water amount information M in the second embodiment represents the required water amount U for each combination of the engine speed NE and the engine load factor KL in an orthogonal coordinate system with the engine speed NE as the X-axis and the engine load factor KL as the Y-axis. As in the first embodiment, the individual map MX is created in advance by experiments or simulations using the internal combustion engine 10 having the specifications described in FIG. 1. That is, the individual map MX represents the correspondence between the engine speed NE, the engine load factor KL, and the required water amount U when the fuel for the internal combustion engine 10 is hydrogen gas. Furthermore, the content of the individual map MX, which is the operating region in which the turbocharger 40 operates, represents the correspondence relationship between the engine speed NE and engine load factor KL, and the required water amount U, when the turbocharger 40 is operating. A group of such individual maps MX is created in advance for each cylinder 12, and is stored in the memory 92 as water amount information M.

[0034] In step S10 of the water injection control, the CPU 91 acquires the target water injection amount for each cylinder 12 as follows. To acquire the target water injection amount for a given cylinder 12, the CPU 91 first reads from the memory 92 the individual map MX for the target cylinder 12 in the water amount information M. The CPU 91 then calculates, as the target water injection amount, the required water amount U corresponding to the current engine speed NE and engine load factor KL based on the individual map MX read from the memory 92. In this manner, the CPU 91 calculates the target water injection amount for each cylinder 12. The CPU 91 calculating the target water injection amount is equivalent to the CPU 91 acquiring the target water injection amount. In this way, the CPU 91 acquires the required water amount U for each cylinder 12 as the target water injection amount for each cylinder 12 based on the water amount information M. After executing the process of step S10, the CPU 91 performs the process of step S20, as in the first embodiment.

[0035] <Effects of the second embodiment> The configuration of the second embodiment can achieve the same effects as those of (1), (2), and (3) of the first embodiment. In addition, the configuration of the second embodiment can eliminate the basic information B from the memory 92. That is, the amount of information related to water injection control that needs to be stored in the memory 92 can be reduced. This contributes to ensuring free space in the memory 92. Furthermore, the configuration of the second embodiment can reduce the processing load on the CPU 91 related to the processing of step S10, as described below. That is, for example, in the first embodiment, the CPU 91 calculates two parameters, the basic water volume and the EGR water volume Q, to obtain the target water injection volume for one cylinder 12, and performs subtraction processing for these two parameters. In contrast, in the second embodiment, the CPU 91 needs to calculate only the required water volume U to obtain the target water injection volume for one cylinder 12. The CPU 91 then treats this required water volume U as the target water injection volume. Therefore, the configuration of the second embodiment can reduce the processing load on the CPU 91.

[0036] <Example of change> The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0037] The unit period is not limited to the examples in the above embodiments. The unit period may be set to a length appropriate for defining the EGR water amount Q, the basic water amount, and the required water amount U. The unit period may be determined using an absolute time length as a measure, rather than using the combustion cycle of the internal combustion engine 10 or the rotation amount of the crankshaft 11 as a measure.

[0038] The water amount parameter defining the individual map MX is not limited to the examples in the above embodiments. The water amount parameter may be any parameter related to the EGR water amount Q. For example, the water amount parameter may be a value obtained by multiplying the EGR water amount Q by a correction coefficient or the like.

[0039] The operating parameters defining the individual map MX are not limited to those described in the above embodiments. The operating parameters may be any parameters related to the operating state of the internal combustion engine 10. For example, the operating parameters may be the gas temperatures in the respective passages. Depending on the operating parameters employed, sensors such as temperature sensors may be attached to the internal combustion engine 10 to enable the CPU 91 to grasp the current values ​​of the operating parameters.

[0040] The number of operating parameters associated with the water volume parameters in the individual map MX is not limited to the example in the above embodiment. The individual map MX may define a correspondence relationship between one or more operating parameters and water volume parameters.

[0041] As with the above-described modified example, the number of operating parameters associated with the basic water volume for the basic information B in the first embodiment is not limited to that in the above-described embodiment. The format of the individual map MX is not limited to a graph. For example, the individual map MX may be a mathematical formula. The format of the individual map MX is not limited as long as it represents the correspondence between the operating parameters and the water volume parameters.

[0042] As in the above-described modified example, the format of the basic information B in the first embodiment is not limited to the example in the above-described embodiment. The overall configuration of the internal combustion engine 10 is not limited to the example of the above embodiment. For example, the number of cylinders 12 may be changed from the example of the above embodiment. The type of the turbocharger 40 may be changed from the example of the above embodiment. For example, the turbocharger 40 may be a nozzle vane type. The turbocharger 40 may be eliminated from the internal combustion engine 10. In omitting the turbocharger 40, the intercooler 23 may also be eliminated. The water injection valve 60 may be changed to a type that directly injects water into the cylinders 12. The water injection valve 60 may be capable of supplying water into the cylinders 12 and may be provided for each cylinder 12. The fuel injected by the fuel injection valve 14 may be a fuel other than hydrogen gas. The fuel injected by the fuel injection valve 14 may be, for example, gasoline. The fuel injection valve 14 may be a type that supplies fuel into the cylinders 12 via the intake passage 20. The internal combustion engine 10 may include a plurality of cylinders 12, a water injection valve 60 for each cylinder 12, an EGR passage 50 connecting the intake passage 20 and the exhaust passage 30, and an EGR cooler 52 located midway along the EGR passage 50.

[0043] If the configuration of the internal combustion engine 10 is changed from the example of the above embodiment, the content of the individual map MX will also change accordingly. For example, if gasoline is used as the fuel injected by the fuel injection valve 14, the experiments or simulations for creating the individual map MX are performed on the assumption that the fuel injected by the fuel injection valve 14 is gasoline. The individual map MX represents the correspondence between the operating parameters and the water amount parameters when the fuel of the internal combustion engine 10 is gasoline. In this way, the individual map MX and, ultimately, the water amount information M are created in advance specifically for the target internal combustion engine 10. Therefore, depending on the configuration of the internal combustion engine 10, the water amount information M may not represent the correspondence between the operating parameters and the water amount parameters for the following two cases. One of the two cases is when the fuel of the internal combustion engine 10 is hydrogen gas. The other of the two cases is when the turbocharger 40 is operating. [Explanation of symbols]

[0044] 10...Internal combustion engine 10A...Engine body 12...Cylinder 14...Fuel injection valve 20...Intake passage 30...Exhaust passage 40...Turbocharger 50...EGR passage 52...EGR cooler 60...Water injection valve 90...Control device 91...CPU 92...Memory

Claims

1. an engine body into which a plurality of cylinders are partitioned; a water injection valve for each of the cylinders for supplying water to each of the cylinders; an EGR passage that introduces a portion of the exhaust gas flowing through the exhaust passage into the intake passage as EGR gas; an EGR cooler provided in the EGR passage for cooling the EGR gas; The present invention is applied to an internal combustion engine having An execution unit and a storage unit, When the amount of condensed water generated in the EGR passage and flowing into one of the cylinders in a unit period is defined as an EGR water amount, the storage unit stores information representing a correspondence relationship between an operating parameter related to an operating state of the internal combustion engine and a water amount parameter related to the EGR water amount for each of the cylinders; The execution unit: During operation of the internal combustion engine, a first process of subtracting the EGR water amount for each cylinder from a basic water amount according to an operating state of the internal combustion engine based on the information, and acquiring the result as a target water injection amount for each cylinder; a second process of controlling each of the water injection valves so as to inject the target water injection amount for each of the cylinders; Control device for internal combustion engines.

2. the internal combustion engine uses hydrogen gas as fuel, The information indicates a correspondence relationship between the operating parameters and the water amount parameters when the fuel of the internal combustion engine is hydrogen gas. The control device for an internal combustion engine according to claim 1.

3. the internal combustion engine includes a supercharger that supercharges intake air flowing through the intake passage, The information indicates a correspondence relationship between the operating parameters and the water amount parameters when the turbocharger is in operation. The control device for an internal combustion engine according to claim 1 or 2.

4. an engine body into which a plurality of cylinders are partitioned; a water injection valve for each of the cylinders for supplying water to each of the cylinders; an EGR passage that introduces a portion of the exhaust gas flowing through the exhaust passage into the intake passage as EGR gas; an EGR cooler provided in the EGR passage for cooling the EGR gas; A control device applied to an internal combustion engine comprising: a control device that stores information representing, for each cylinder, a correspondence relationship between an operating parameter relating to an operating state of the internal combustion engine and a water amount parameter relating to the EGR water amount, where the amount of condensed water generated in the EGR passage and flowing into one of the cylinders in a unit period is defined as an EGR water amount; During operation of the internal combustion engine, a first process of subtracting the EGR water amount for each cylinder from a basic water amount according to an operating state of the internal combustion engine based on the information, and acquiring the result as a target water injection amount for each cylinder; a second process of controlling each of the water injection valves so as to inject the target water injection amount for each of the cylinders. Program for internal combustion engines.

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