Internal combustion engine control device

Abstract

To provide an internal combustion engine control device capable of suppressing an increase in a temperature in a cylinder while an internal combustion engine is performing a high-load operation.SOLUTION: When EGR gas is introduced to an intake passage via an EGR passage, a control device determines whether or not condensation water is generated at a merging portion that is a portion to which the EGR passage is connected in the intake passage (S23). The control device determines whether or not an internal combustion engine is performing a high-load operation on the basis of engine speed and engine torque (S31). When determining that condensation water is generated at the merging portion in the intake passage (YES in S23) and determining that the internal combustion engine is performing the high-load operation (YES in S31), the control device reduces a collection amount of the condensation water by using a collection device (S35).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine control device that is applied to an internal combustion engine that uses gaseous fuel. [Background technology]

[0002] Patent Document 1 discloses an internal combustion engine equipped with an EGR device that recirculates a portion of the exhaust gas discharged from inside the cylinder to the intake passage. The exhaust gas recirculated to the intake passage by the EGR device is called "EGR gas." "EGR" is an abbreviation for "Exhaust Gas Recirculation."

[0003] The EGR device includes an EGR passage connected to an intake passage, an EGR cooler for cooling EGR gas flowing through the EGR passage, and a collector for collecting condensed water generated in the EGR passage. The EGR passage is connected to a portion of the intake passage upstream of the intercooler. When a control device for controlling the internal combustion engine determines that condensed water will be generated in the intake passage due to cooling by the intercooler, the control device reduces the cooling efficiency of the EGR gas by the EGR cooler to suppress the generation of condensed water in the intake passage. This suppresses the flow of condensed water into the cylinder through the intake passage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-57788 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an internal combustion engine that introduces liquid fuel such as gasoline into the cylinders, the temperature rise inside the cylinders can be suppressed as the liquid fuel vaporizes inside the cylinders. However, in an internal combustion engine that introduces gaseous fuel such as hydrogen into the cylinders, the temperature inside the cylinders is likely to rise because the effect of suppressing the temperature rise inside the cylinders caused by the introduction of fuel cannot be expected compared to when liquid fuel is introduced into the cylinders. [Means for solving the problem]

[0006] The internal combustion engine control device for solving the above problems is applied to an internal combustion engine including a cylinder, an intake passage through which air to be introduced into the cylinder flows, an exhaust passage through which exhaust gas discharged from the cylinder flows, and an EGR device that recirculates a portion of the exhaust gas flowing through the exhaust passage to the intake passage as EGR gas, and in which gaseous fuel is supplied to the cylinder. The EGR device includes an EGR passage connected to the intake passage and through which the EGR gas flows toward the intake passage, and a collector that collects condensed water generated in the EGR passage. The internal combustion engine control device, when EGR gas is introduced into the intake passage through the EGR passage, determines whether condensation occurs at a junction portion of the intake passage to which the EGR passage is connected, determines whether the internal combustion engine is operating at a high load based on the rotation speed of the output shaft of the internal combustion engine and the output torque of the internal combustion engine, and reduces the amount of condensation water collected by the collection device when it is determined that condensation occurs at the junction portion of the intake passage and that the internal combustion engine is operating at a high load. Effect of the Invention

[0007] The above-described internal combustion engine control device has an effect of suppressing an increase in temperature inside the cylinder when the internal combustion engine is operating under high load. [Brief description of the drawings]

[0008] [Figure 1]FIG. 1 is a configuration diagram showing an internal combustion engine control device according to a first embodiment and an internal combustion engine to which the internal combustion engine control device is applied. [Diagram 2] FIG. 2 is a map for identifying the operating region of the internal combustion engine shown in FIG. [Diagram 3] FIG. 3 is a flowchart showing a processing routine executed by the internal combustion engine control device of the first embodiment. [Figure 4] FIG. 4 is a configuration diagram showing an internal combustion engine control device according to the second embodiment and an internal combustion engine to which the internal combustion engine control device is applied. [Diagram 5] FIG. 5 is a flowchart showing the first half of a processing routine executed by the internal combustion engine control device of the second embodiment. [Figure 6] FIG. 6 is a flowchart showing the latter half of the processing routine executed by the internal combustion engine control device of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) A first embodiment of an internal combustion engine control device will be described below with reference to Figs. 1 illustrates an internal combustion engine 10 mounted on a vehicle, and a control device 100 applied to the internal combustion engine 10. The control device 100 corresponds to an "internal combustion engine control device."

[0010] <Internal combustion engine> The internal combustion engine 10 includes a plurality of cylinders 11, an intake passage 12, a plurality of fuel injection valves 13, and an exhaust passage 14. A piston 15 is housed in each of the cylinders 11. The pistons 15 are each connected to a crankshaft 17 via a connecting rod 16. The pistons 15 reciprocate in the plurality of cylinders 11, causing the crankshaft 17 to rotate. The crankshaft 17 corresponds to the "output shaft of the internal combustion engine 10."

[0011] The intake passage 12 is connected to the multiple cylinders 11. The intake passage 12 is a passage through which air to be introduced into the multiple cylinders 11 flows. An intercooler 18 that cools the air flowing through the intake passage 12 is provided in the intake passage 12. A throttle valve 19 that adjusts the amount of air to be introduced into the multiple cylinders 11 is provided in the intake passage 12 downstream of the intercooler 18.

[0012] Each of the multiple fuel injection valves 13 injects gaseous fuel to be supplied into the cylinder 11. One example of the gaseous fuel is hydrogen gas. In the example shown in Fig. 1, the fuel injection valve 13 is a port injection valve that injects gaseous fuel into a portion of the intake passage 12 downstream of the throttle valve 19. The internal combustion engine 10 may be equipped with an in-cylinder injection valve that directly injects gaseous fuel into the cylinder 11 as the fuel injection valve 13.

[0013] In each of the cylinders 11, a mixture containing air and gaseous fuel is burned by spark discharge from the spark plug 20. This generates exhaust gas in each of the cylinders 11. The exhaust gas is discharged from the cylinders 11 to an exhaust passage 14. The exhaust gas flows through the exhaust passage 14.

[0014] The internal combustion engine 10 includes an EGR device 30. The EGR device 30 is a device that recirculates a part of the exhaust gas flowing through the exhaust passage 14 to the intake passage 12. The exhaust gas recirculated to the intake passage 12 via the EGR device 30 is called "EGR gas". The EGR device 30 includes an EGR passage 31, an EGR cooler 32, an EGR valve 34, and a collector 35. The EGR passage 31 is a passage that distributes the EGR gas toward the intake passage 12. A first end of the EGR passage 31 is connected to the exhaust passage 14. A second end of the EGR passage 31 is connected to the intake passage 12. In the example shown in FIG. 1, the second end of the EGR passage 31 is connected to a portion of the intake passage 12 between the intercooler 18 and the throttle valve 19. A portion of the intake passage 12 to which the EGR passage 31 is connected is also called a "junction portion".

[0015] The EGR cooler 32 cools the EGR gas flowing through the EGR passage 31. For example, a water-cooled cooling device is used as the EGR cooler 32. In this case, the EGR device 30 includes an electric pump 33 that adjusts the amount of cooling water supplied to the EGR cooler 32. The amount of cooling water supplied to the EGR cooler 32 is adjusted by adjusting the operation of the pump 33. For example, when the amount of cooling water supplied to the EGR cooler 32 is increased, the efficiency of cooling the EGR gas by the EGR cooler 32 increases. On the other hand, when the amount of supply is reduced, the efficiency of cooling the EGR gas by the EGR cooler 32 decreases.

[0016] The EGR valve 34 is disposed in a portion of the EGR passage 31 downstream of the EGR cooler 32. The EGR valve 34 is an electronically controlled valve. The larger the EGR opening degree, which is the opening degree of the EGR valve 34, the greater the flow rate of EGR gas in the EGR passage 31. In other words, the amount of EGR gas returned to the intake passage 12 increases.

[0017] The collection device 35 is disposed in the EGR passage 31 downstream of the EGR valve 34. The collection device 35 is disposed in the EGR passage 31 upstream of a connection portion with the intake passage 12. In other words, the collection device 35 is installed such that the EGR cooler 32 is located upstream of the collection device 35 in the EGR passage 31. The collection device 35 is configured to collect condensed water generated in the EGR passage 31.

[0018] An example of the collection device 35 will be described. The example of the collection device 35 has a first passage and a second passage arranged in parallel with each other, a collector arranged in the first passage, and an electronically controlled switching valve. Both the first passage and the second passage are connected to the EGR passage 31. The switching valve is configured to adjust the distribution ratio of EGR gas flowing into the first passage among the EGR gas flowing through the EGR passage 31. The collector collects the condensed water that has flowed into the first passage. In the collection device 35, the greater the distribution ratio, the higher the collection efficiency of the condensed water.

[0019] The internal combustion engine 10 is equipped with an exhaust-driven supercharger 40. The supercharger 40 has a turbine 41 arranged in the exhaust passage 14 and a compressor 42 arranged in the intake passage 12. The turbine 41 is arranged downstream of a portion of the exhaust passage 14 to which the EGR passage 31 is connected. The compressor 42 is arranged in the intake passage 12 upstream of the intercooler 18. The turbine 41 is operated by the flow of exhaust gas flowing through the exhaust passage 14. The compressor 42 pressurizes the air flowing through the intake passage 12 by operating in synchronization with the turbine 41.

[0020] The internal combustion engine 10 is equipped with a plurality of sensors that output signals according to the detection results to the control device 100. The plurality of sensors include, for example, a crank angle sensor 51, an air flow meter 52, and an outside air temperature sensor 53. The crank angle sensor 51 outputs a signal according to the rotation speed of the crankshaft 17. The air flow meter 52 detects the amount of air flowing through a portion of the intake passage 12 upstream of the compressor 42. The outside air temperature sensor 53 detects the temperature outside the internal combustion engine 10.

[0021] The rotation speed of the crankshaft 17 based on the signal from the crank angle sensor 51 is referred to as the "engine speed NE." The flow rate of air based on the detection result of the air flow meter 52 is referred to as the "intake air amount GA." The temperature based on the detection result of the outside air temperature sensor 53 is referred to as the "outside air temperature TMP."

[0022] <Control device> An example of the control device 100 is an electronic control device. In this case, the control device 100 includes a CPU 101 and a memory 102. The memory 102 stores various control programs executed by the CPU 101. The CPU 101 executes the control programs, allowing the control device 100 to control the operation of the internal combustion engine 10. In this embodiment, the control device 100 controls the EGR device 30 in accordance with the operating range of the internal combustion engine 10.

[0023] 2 shows a map for grasping the operating range of the internal combustion engine 10 based on the engine speed NE and the engine torque TQ. The engine torque TQ is the output torque of the internal combustion engine 10. The control device 100 calculates the engine torque TQ so that, for example, the larger the accelerator opening degree, the larger the value becomes.

[0024] The operating range of the internal combustion engine 10 can be divided into a low-load operating range R1, a medium-load operating range R2, and a high-load operating range R3. The low-load operating range R1 is an operating range in which the engine load, which is the load on the internal combustion engine 10, is small. When at least one of the engine speed NE and the engine torque TQ is relatively low, the control device 100 determines that the current operating range of the internal combustion engine 10 is the low-load operating range R1. The medium-load operating range R2 is an operating range in which the engine load is medium. When the engine speed NE and the engine torque TQ are medium, the control device 100 determines that the current operating range of the internal combustion engine 10 is the medium-load operating range R2. The high-load operating range R3 is an operating range in which the engine load is relatively high. When both the engine speed NE and the engine torque TQ are relatively high, the control device 100 determines that the current operating range of the internal combustion engine 10 is the high-load operating range R3.

[0025] Here, by introducing the EGR gas into the cylinder 11, the fuel injection amount of the fuel injection valve 13 is reduced. Therefore, the temperature inside the cylinder 11 is less likely to rise. Furthermore, by introducing the condensed water generated in the EGR passage 31 into the cylinder 11, the effect of suppressing the temperature rise inside the cylinder 11 is further enhanced.

[0026] Even in the internal combustion engine 10 using hydrogen as fuel, the temperature in the cylinder 11 does not rise much during low-load operation. Therefore, when the operating range of the internal combustion engine 10 is the low-load operating range R1, that is, when the internal combustion engine 10 is operating at low load, the need to introduce EGR gas into the plurality of cylinders 11 is low. However, when the operating range of the internal combustion engine 10 is not the low-load operating range R1, the temperature in the cylinder 11 is more likely to rise compared to the case where the operating range is the low-load operating range R1. When the operating range of the internal combustion engine 10 is the high-load operating range R3, the temperature in the cylinder 11 is even more likely to rise compared to the case where the operating range is the medium-load operating range R2. Therefore, when the internal combustion engine 10 is operating at medium load, it is preferable to introduce EGR gas into the plurality of cylinders 11. However, when the internal combustion engine 10 is operating at medium load, the need to introduce condensed water into the plurality of cylinders 11 is low. On the other hand, when the internal combustion engine 10 is operating at high load, it is preferable to introduce both EGR gas and condensed water into the plurality of cylinders 11.

[0027] <Processing for Controlling the EGR Device> Referring to FIG. 3, the processing routine executed by the control device 100 when controlling the EGR device 30 will be described. When the internal combustion engine 10 is operating, the control device 100 repeatedly executes this processing routine at a predetermined cycle.

[0028] In step S11, the control device 100 identifies the operating range of the internal combustion engine 10 using the map shown in FIG. 2. In the next step S13, the control device 100 determines whether the internal combustion engine 10 is operating at low load. If the control device 100 determines that the internal combustion engine 10 is operating at low load (S13: YES), the process proceeds to step S15. On the other hand, if the control device 100 determines that the internal combustion engine 10 is not operating at low load (S13: NO), the process proceeds to step S21.

[0029] In step S15, the control device 100 closes the EGR valve 34 to stop the EGR device 30 from recirculating the EGR gas to the intake passage 12. After that, the control device 100 temporarily ends this processing routine.

[0030] In step S21, the control device 100 executes a process for determining whether or not there is condensed water. In this process, the control device 100 calculates a first dew point TMPd1, which is a temperature at which water vapor contained in the EGR gas condenses. At this time, the control device 100 calculates the first dew point TMPd1 based on the temperature, humidity, and pressure of the EGR passage 31. For example, the control device 100 calculates the first dew point TMPd1 so that the higher the temperature of the EGR passage 31, the higher the first dew point TMPd1 becomes. The control device 100 calculates the first dew point TMPd1 so that the higher the humidity, the higher the first dew point TMPd1 becomes. The control device 100 calculates the first dew point TMPd1 so that the higher the pressure, the higher the first dew point TMPd1 becomes.

[0031] In addition, in the determination process, the control device 100 calculates a first gas temperature TMPg1, which is the temperature of the joining portion of the intake passage 12 with the EGR passage 31. The control device 100 calculates the first gas temperature TMPg1 based on the outside air temperature TMP, the temperature of the EGR gas passing through the EGR valve 34, the intake air amount GA, and the reflux amount of the EGR gas. When a sensor for detecting the temperature of the portion downstream of the EGR valve 34 in the EGR passage 31 is provided, the control device 100 can acquire the temperature of the EGR gas based on the detection signal of the sensor. The control device 100 can derive the reflux amount of the EGR gas so that the value increases as the opening degree of the EGR valve 34 increases. Then, the control device 100 calculates the first gas temperature TMPg1 so that the higher the outside air temperature TMP, the higher the first gas temperature TMPg1. The control device 100 calculates the first gas temperature TMPg1 so that the smaller the intake air amount GA, the higher the first gas temperature TMPg1. The control device 100 calculates the first gas temperature TMPg1 so that the higher the temperature of the EGR gas, the higher the first gas temperature TMPg1. The control device 100 calculates the first gas temperature TMPg1 so that the larger the reflux amount of the EGR gas, the higher the first gas temperature TMPg1.

[0032] After calculating the first dew point TMPd1 and the first gas temperature TMPg1, the control device 100 transitions the process to step S23. In step S23, the control device 100 determines whether or not condensation will occur at the above-mentioned joining portion of the intake passage 12. For example, the control device 100 determines that condensation will occur when the first gas temperature TMPg1 is equal to or lower than the first dew point TMPd1. On the other hand, the control device 100 determines that condensation will not occur when the first gas temperature TMPg1 is higher than the first dew point TMPd1. If the control device 100 determines that condensation will occur (S23: YES), the process proceeds to step S31. On the other hand, if the control device 100 determines that condensation will not occur (S23: NO), the process proceeds to step S25.

[0033] In step S25, the control device 100 controls the opening of the EGR valve 34 according to the required EGR amount. The required EGR amount is a required value for the amount of EGR gas returned to the intake passage 12 via the EGR passage 31. For example, the higher the load of the internal combustion engine 10, the larger the required EGR amount is set. The control device 100 may operate the EGR valve 34 so that the opening becomes larger as the required EGR amount increases. Then, the control device 100 temporarily ends this processing routine.

[0034] In step S31, the control device 100 determines whether or not the internal combustion engine 10 is operating under high load. When the control device 100 determines that the internal combustion engine 10 is operating under high load (S31: YES), the control device 100 shifts the process to step S35. On the other hand, when the control device 100 determines that the internal combustion engine 10 is not operating under high load (S31: NO), the control device 100 can determine that the internal combustion engine 10 is operating under medium load, and shifts the process to step S33.

[0035] In step S33, the control device 100 executes a process for increasing the amount of condensed water collected by the collection device 35. It is assumed that the collection device 35 has the above-described configuration. In this case, the control device 100 operates the switching valve so as to increase the flow rate of EGR gas to the first passage in which the collector is disposed, compared to the case in which it is determined that the internal combustion engine 10 is operating at high load. Then, the control device 100 transitions the process to step S25.

[0036] In step S35, the control device 100 executes a process for reducing the amount of condensed water collected by the collection device 35. It is assumed that the collection device 35 has the above-described configuration. In this case, the control device 100 operates the switching valve so as to reduce the flow rate of EGR gas to the first passage in which the collector is disposed, compared to the case where it is determined that the internal combustion engine 10 is not operating at high load. This allows the control device 100 to reduce the amount of condensed water collected by the collection device 35. Then, the control device 100 transitions the process to step S25.

[0037] <Actions and Effects of the Present Embodiment> (1-1) When EGR gas is introduced into the intake passage 12 via the EGR passage 31, the control device 100 determines whether or not condensation occurs at the joining portion of the intake passage 12 (S23). The control device 100 determines whether or not the internal combustion engine 10 is operating at high load (S31). Then, when the control device 100 determines that condensation occurs at the joining portion (S23: YES) and determines that the internal combustion engine 10 is operating at high load (S31: YES), it reduces the amount of condensation collected by the collection device 35 (S35).

[0038] This increases the amount of condensed water flowing into the intake passage 12 via the EGR passage 31 together with the EGR gas. The condensed water that has flowed into the intake passage 12 flows into the multiple cylinders 11 together with the air and EGR gas. In the cylinders 11, the condensed water vaporizes due to an increase in pressure inside the cylinders 11 caused by the combustion of the air-fuel mixture. At this time, the latent heat of vaporization of the condensed water suppresses a temperature increase inside the cylinders 11. Therefore, the control device 100 can suppress a temperature increase inside the cylinders 11 when the internal combustion engine 10 is operating under high load.

[0039] (1-2) When condensed water flows through the intake passage 12 or flows into the cylinder 11, the characteristics of the components of the internal combustion engine 10 that come into contact with the condensed water are likely to change. Therefore, when the control device 100 determines that condensation will occur at the above-mentioned confluence portion of the intake passage 12 (S23: YES) and determines that the internal combustion engine 10 is not operating at high load (S31: NO), it increases the amount of condensation collected by the collection device 35 (S33).

[0040] This reduces the amount of condensed water flowing from the EGR passage 31 into the intake passage 12. This prevents the condensed water from adhering to the components of the internal combustion engine 10. Moreover, since the internal combustion engine 10 is not operating at high load, even if the amount of condensed water flowing into the cylinder 11 is reduced, the temperature rise in the cylinder 11 is sufficiently suppressed by introducing EGR gas into the cylinder 11. Therefore, the control device 100 can suppress the progression of changes in the characteristics of the components of the internal combustion engine 10 while suppressing the temperature rise in the cylinder 11.

[0041] (1-3) In the internal combustion engine 10, hydrogen is supplied as fuel into the multiple cylinders 11. The ignitability of hydrogen is higher than that of liquid fuels such as gasoline. Therefore, pre-ignition is likely to occur in the internal combustion engine 10. In order to suppress the occurrence of pre-ignition, it is preferable to make it difficult for the temperature inside the cylinders 11 to become high.

[0042] In this regard, the control device 100 is configured to introduce condensed water generated by cooling the EGR gas into the multiple cylinders 11 when the internal combustion engine 10 is operating under high load. This suppresses a rise in temperature in the multiple cylinders 11 when the internal combustion engine 10 is operating under high load. Therefore, the control device 100 can suppress the occurrence of pre-ignition in the multiple cylinders 11.

[0043] Second embodiment A second embodiment of an internal combustion engine control device will be described with reference to Figures 4 to 6. Note that in the second embodiment, the structure of an internal combustion engine to which the internal combustion engine control device is applied is different from that of the first embodiment. In the following description, the parts that differ from the first embodiment will be mainly described, and the same reference numerals will be used to designate the same members as in the first embodiment, and duplicated description will be omitted.

[0044] 4 illustrates an internal combustion engine 10A mounted on a vehicle, and a control device 1000 to which the internal combustion engine 10A is applied. The control device 1000 corresponds to an "internal combustion engine control device." <Internal combustion engine> Like the internal combustion engine 10, the internal combustion engine 10A includes a plurality of cylinders 11, an intake passage 12, an exhaust passage 14, and a supercharger 40. The internal combustion engine 10A includes an EGR device 30A.

[0045] The EGR device 30A is a device that recirculates a part of the exhaust gas flowing through the exhaust passage 14 to the intake passage 12 as EGR gas, similar to the EGR device 30. The EGR device 30A includes an EGR passage 31A, an EGR cooler 32, an EGR valve 34, and a collector 35. The EGR passage 31A is a passage that distributes the EGR gas toward the intake passage 12. A first end of the EGR passage 31A is connected to the exhaust passage 14. A second end of the EGR passage 31A is connected to the intake passage 12. In the example shown in FIG. 1, the first end of the EGR passage 31A is connected to a portion of the exhaust passage 14 that is upstream of the turbine 41. The second end of the EGR passage 31A is connected to a portion of the intake passage 12 that is upstream of the compressor 42.

[0046] The internal combustion engine 10A is provided with a plurality of sensors that output signals according to the detection results. For example, in addition to the crank angle sensor 51, the air flow meter 52, and the outside air temperature sensor 53, the plurality of sensors include a compressor rotation speed sensor 54. The compressor rotation speed sensor 54 detects the rotation speed of the blades of the compressor 42. The rotation speed based on the detection result of the compressor rotation speed sensor 54 is referred to as the "compressor rotation speed NC".

[0047] <Control device> An example of the control device 1000 is an electronic control device. In this case, similar to the control device 100, the control device 1000 includes a CPU 101 and a memory 102.

[0048] <Processing for controlling the EGR device> Referring to FIGS. 5 and 6, a processing routine executed by the control device 1000 when controlling the EGR device 30A will be described. When the internal combustion engine 10A is operating, the control device 1000 repeatedly executes this processing routine at a predetermined cycle.

[0049] In step S51, the control device 1000 specifies the operating region of the internal combustion engine 10A in the same manner as in step S11 above. In the next step S53, the control device 1000 determines whether the internal combustion engine 10A is operating at low load. If the control device 1000 determines that the internal combustion engine 10A is operating at low load (S53: YES), the process proceeds to step S55. On the other hand, if the control device 1000 determines that the internal combustion engine 10A is not operating at low load (S53: NO), the process proceeds to step S61.

[0050] In step S55, the control device 1000 closes the EGR valve 34 in the same manner as in step S15 above. Then, the control device 1000 temporarily ends this processing routine. In step S61, the control device 1000 executes a first determination process for condensed water. The first determination process is the same as the condensed water determination process in the above-mentioned step S21. After calculating the above-mentioned first dew point TMPd1 and first gas temperature TMPg1, the control device 1000 shifts the process to step S63.

[0051] In step S63, similar to step S23, the control device 1000 determines whether or not condensation occurs at the junction with the EGR passage 31A in the intake passage 12. If the control device 1000 determines that condensation occurs at the junction (S63: YES), the process proceeds to step S81. On the other hand, if the control device 1000 determines that condensation does not occur at the junction (S63: NO), the process proceeds to step S65.

[0052] In step S65, the control device 1000 executes a second determination process for condensed water. In the second determination process, a second dew point TMPd2 is calculated, which is a temperature at which water vapor contained in the gas pressurized by the compressor 42 in the intake passage 12 condenses. When the gas pressurized by the compressor 42 is defined as a "pressurized gas", the control device 1000 calculates the second dew point TMPd2 based on the temperature, humidity, and pressure of the pressurized gas. For example, the control device 1000 calculates the second dew point TMPd2 so that the higher the temperature of the pressurized gas, the higher the second dew point TMPd2. The control device 1000 calculates the second dew point TMPd2 so that the higher the humidity of the pressurized gas, the higher the second dew point TMPd2. The control device 1000 calculates the second dew point TMPd2 so that the higher the supercharging pressure, which is the pressure of the pressurized gas, the higher the second dew point TMPd2.

[0053] Furthermore, in the second determination process, the control device 1000 calculates a second gas temperature TMPg2, which is the temperature of the pressurized gas cooled by the intercooler 18. For example, if a sensor is provided to detect the temperature of a portion of the intake passage 12 downstream of the intercooler 18, the control device 1000 can calculate the second gas temperature TMPg2 based on a detection signal of the sensor.

[0054] After calculating the second dew point TMPd2 and the second gas temperature TMPg2, the control device 1000 transitions the process to step S67. In step S67, the control device 1000 determines whether or not condensation will occur in the intake passage 12 due to cooling of the pressurized gas by the intercooler 18. For example, the control device 1000 determines that condensation will occur when the second gas temperature TMPg2 is equal to or lower than the second dew point TMPd2. On the other hand, the control device 1000 determines that condensation will not occur when the second gas temperature TMPg2 is higher than the second dew point TMPd2. If the control device 1000 determines that condensation will occur (S67: YES), the control device 1000 shifts the process to step S71. On the other hand, if the control device 1000 determines that condensation will not occur (S67: NO), the control device 1000 shifts the process to step S69.

[0055] In step S69, the control device 1000 controls the opening degree of the EGR valve 34 in accordance with the required EGR amount, similarly to step S25 described above, and then the control device 1000 temporarily ends this processing routine.

[0056] In step S71, the control device 1000 determines whether the internal combustion engine 10A is operating under high load. When the control device 1000 determines that the internal combustion engine 10A is operating under high load (S71: YES), the control device 1000 shifts the process to step S69. On the other hand, when the control device 1000 determines that the internal combustion engine 10A is not operating under high load (S71: NO), the control device 1000 can determine that the internal combustion engine 10A is operating under medium load, and shifts the process to step S73.

[0057] In step S73, the control device 1000 executes a process for increasing the cooling efficiency of the EGR gas by the EGR cooler 32. For example, the control device 1000 increases the amount of cooling water supplied from the pump 33 to the EGR cooler 32, compared to when the internal combustion engine 10A is not operating at high load, thereby increasing the cooling efficiency of the EGR cooler 32. Thereafter, the control device 1000 transitions the process to step S69.

[0058] In step S81, the control device 1000 judges whether the internal combustion engine 10A is operating under high load. When the control device 1000 judges that the internal combustion engine 10A is operating under high load (S81: YES), the control device 1000 shifts the process to step S83. On the other hand, when the control device 1000 judges that the internal combustion engine 10A is not operating under high load (S81: NO), the control device 1000 can determine that the internal combustion engine 10A is operating under medium load, and shifts the process to step S69.

[0059] In step S83, the control device 1000 determines whether or not the compressor rotation speed NC is higher than a judgment rotation speed NCth. The judgment criterion for determining whether or not condensed water may be allowed to flow into the compressor 42 is set as the judgment rotation speed NCth.

[0060] Here, if the compressor rotation speed NC is high, there is a risk that the blades of the compressor 42 will be damaged when water droplets that have flowed into the compressor 42 collide with them. On the other hand, if the compressor rotation speed NC is relatively low, the blades will not be damaged even when water droplets that have flowed into the compressor 42 collide with them. Therefore, it is preferable to set the compressor rotation speed NC as the judgment rotation speed NCth at a value that will not damage the blades of the compressor 42 due to the water droplets when condensed water is introduced into the compressor 42.

[0061] If the compressor speed NC is higher than the determination speed NCth (S83: YES), the control device 1000 shifts the process to step S85. On the other hand, if the compressor speed NC is equal to or lower than the determination speed NCth (S83: NO), the control device 1000 shifts the process to step S87.

[0062] In step S85, the control device 1000 executes a process to reduce the cooling efficiency of the EGR gas by the EGR cooler 32, compared to when it is determined that the compressor rotation speed NC is equal to or lower than the determination rotation speed NCth. For example, the control device 1000 reduces the cooling efficiency of the EGR cooler 32 by reducing the amount of cooling water supplied from the pump 33 to the EGR cooler 32. However, the control device 1000 adjusts the cooling efficiency of the EGR cooler 32 so that condensation water is generated by cooling the pressurized gas by the intercooler 18 while suppressing the generation of condensation water at the above-mentioned joining portion of the intake passage 12. Thereafter, the control device 1000 transitions the process to step S69.

[0063] In step S87, similarly to step S35, the control device 1000 executes the process of reducing the amount of condensed water collected by the collection device 35. Then, the control device 1000 transitions the process to step S69.

[0064] <Actions and Effects of the Present Embodiment> In this embodiment, in addition to the same effects and advantages as those (1-2) and (1-3) of the first embodiment, the following effects can be further obtained.

[0065] (2-1) When EGR gas is introduced into the intake passage 12 via the EGR passage 31A, the control device 1000 determines whether or not condensation occurs at the joining portion of the intake passage 12 (S63). The control device 1000 determines whether or not the internal combustion engine 10A is operating at a high load (S81). Then, when the control device 1000 determines that condensation occurs at the joining portion of the intake passage 12 (S63: YES), determines that the internal combustion engine 10A is operating at a high load (S81: YES), and further determines that the compressor rotation speed NC is equal to or lower than the determination rotation speed NCth (S83: NO), the control device 1000 reduces the amount of condensation collected by the collection device 35 (S87).

[0066] This increases the amount of condensed water flowing into the intake passage 12 via the EGR passage 31A together with the EGR gas. The condensed water that has flowed into the intake passage 12 flows into the multiple cylinders 11 together with the air and EGR gas. In the cylinders 11, the condensed water vaporizes due to an increase in pressure in the cylinders 11 caused by the combustion of the air-fuel mixture. At this time, the latent heat of vaporization of the condensed water suppresses a temperature increase in the cylinders 11. Therefore, the control device 1000 can suppress a temperature increase in the cylinders 11 when the internal combustion engine 10A is operating under high load.

[0067] (2-2) As described above, when the compressor speed NC is higher than the judgment speed NCth, the components of the compressor 42 may be damaged by the condensed water generated at the joining portion of the intake passage 12 when the condensed water flows into the compressor 42. Therefore, when the control device 1000 determines that condensed water will be generated at the joining portion of the intake passage 12 (S63: YES), determines that the internal combustion engine 10A is operating at a high load (S81: YES), and further determines that the compressor speed NC is higher than the judgment speed NCth (S83: YES), the control device 1000 reduces the cooling efficiency of the EGR gas by the EGR cooler 32.

[0068] This suppresses the generation of condensed water at the joining portion of the intake passage 12. As a result, when the compressor rotation speed NC is relatively high, the condensed water is suppressed from flowing into the compressor 42. Therefore, the control device 1000 can protect the components of the compressor 42.

[0069] Furthermore, the control device 1000 adjusts the cooling efficiency of the EGR cooler 32 so that condensation water is generated in the intake passage 12 by cooling the pressurized gas by the intercooler 18 while suppressing generation of condensation water at the joining portion of the intake passage 12. Therefore, even when the compressor rotation speed NC is higher than the judgment rotation speed NCth, the control device 1000 can supply the condensation water generated in the intake passage 12 by cooling the pressurized gas by the intercooler 18 to the multiple cylinders 11. Therefore, the control device 1000 can protect the components of the compressor 42 and suppress a temperature rise in the cylinders 11 during high load operation of the internal combustion engine 10A.

[0070] (2-3) When the control device 1000 determines that condensation will not occur at the above-mentioned confluence portion of the intake passage 12 (S63: NO), and determines that condensation will occur in the intake passage 12 due to cooling of the pressurized gas by the intercooler 18 (S67: YES), and further determines that the internal combustion engine 10A is not operating under high load (S71: NO), the control device 1000 increases the cooling efficiency of the EGR gas by the EGR cooler 32 compared to when it determines that the internal combustion engine 10A is operating under high load.

[0071] This reduces the amount of condensed water generated by cooling the pressurized gas by the intercooler 18. As a result, the control device 1000 can reduce the amount of condensed water flowing into the multiple cylinders 11 from the intake passage 12 when the internal combustion engine 10A is operating under medium load.

[0072] (2-4) On the other hand, when the control device 1000 determines that condensation will not occur at the above-mentioned confluence portion of the intake passage 12 (S63: NO), and determines that condensation will occur in the intake passage 12 due to cooling of the pressurized gas by the intercooler 18 (S67: YES), and further determines that the internal combustion engine 10A is operating at high load (S71: YES), the control device 1000 reduces the cooling efficiency of the EGR gas by the EGR cooler 32 compared to when it is determined that the internal combustion engine 10A is not operating at high load.

[0073] This increases the amount of condensed water generated by cooling the pressurized gas by the intercooler 18. This increases the amount of condensed water flowing from the intake passage 12 into the multiple cylinders 11. Therefore, the control device 1000 can suppress an increase in temperature in the cylinders 11 when the internal combustion engine 10A is operating under high load.

[0074] <Example of change> The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that they are not technically inconsistent.

[0075] In the above-described second embodiment, if the control device 1000 determines that condensation will occur in the intake passage 12 due to cooling of the pressurized gas by the intercooler 18 (S67: YES), the control device 1000 may increase the cooling efficiency of the EGR gas by the EGR cooler 32 regardless of whether the internal combustion engine 10A is operating under high load.

[0076] In the second embodiment, if the control device 1000 determines that condensation will occur at the above-mentioned confluence portion of the intake passage 12 (S63: YES), and determines that the internal combustion engine 10A is operating at high load (S81: YES), and further determines that the compressor rotational speed NC is equal to or lower than the judgment rotational speed NCth (S83: NO), then it is not necessary to reduce the amount of condensed water collected by the collection device 35.

[0077] In the first embodiment, the internal combustion engine 10 may be an internal combustion engine that does not include the turbocharger 40. In this case, the intercooler 18 does not need to be provided in the intake passage 12.

[0078] The internal combustion engine 10, 10A may have one or more cylinders. The control devices 100 and 1000 are not limited to those equipped with a CPU and ROM and executing software processing. In other words, the control devices 100 and 1000 may have any one of the following configurations (a), (b), and (c).

[0079] (a) The control device 100, 1000 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program codes or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0080] (b) The control devices 100 and 1000 are provided with one or more dedicated hardware circuits for executing various processes. Examples of the dedicated hardware circuits include application specific integrated circuits, i.e., ASIC and FPGA. ASIC is an abbreviation for "Application Specific Integrated Circuit" and "FPGA" is an abbreviation for "Field Programmable Gate Array."

[0081] (c) The control devices 100 and 1000 each include a processor that executes some of the various processes in accordance with a computer program, and a dedicated hardware circuit that executes the remaining processes among the various processes.

[0082] The term "at least one" used herein means "one or more" of the desired options. As an example, the term "at least one" used herein means "only one option" or "both of two options" if the number of options is two. As another example, the term "at least one" used herein means "only one option" or "any combination of two or more options" if the number of options is three or more. [Explanation of symbols]

[0083] 10,10A...internal combustion engine, 11...cylinder, 12...intake passage, 14...exhaust passage, 17...crankshaft, 18...intercooler, 30,30A...EGR device, 31,31A...EGR passage, 32...EGR cooler, 35...collection device, 40...supercharger, 41...turbine, 42...compressor, 100,1000...control device

Claims

1. An internal combustion engine control device that is applied to an internal combustion engine including a cylinder, an intake passage through which air to be introduced into the cylinder flows, an exhaust passage through which exhaust gas discharged from the cylinder flows, and an EGR device that recirculates a portion of the exhaust gas flowing through the exhaust passage to the intake passage as EGR gas, and in which a gaseous fuel is supplied into the cylinder, The EGR device includes an EGR passage connected to the intake passage and through which EGR gas flows toward the intake passage, and a collection device that collects condensed water generated in the EGR passage, The internal combustion engine control device includes: determining whether or not condensation occurs at a confluence portion of the intake passage to which the EGR passage is connected when EGR gas is introduced into the intake passage through the EGR passage; determining whether the internal combustion engine is operating under high load based on a rotation speed of an output shaft of the internal combustion engine and an output torque of the internal combustion engine; When it is determined that condensation occurs at the joining portion of the intake passage and when it is determined that the internal combustion engine is operating at a high load, the amount of condensation collected by the collection device is reduced. Internal combustion engine control device.

2. The internal combustion engine includes: a turbocharger including a turbine provided in the exhaust passage and a compressor operating in synchronization with the turbine and provided in the intake passage; an intercooler that is disposed in the intake passage downstream of the compressor and cools air flowing through the intake passage, the EGR device is disposed in the EGR passage upstream of the collection device and has an EGR cooler that cools the EGR gas flowing through the EGR passage, The joining portion is located in a portion of the intake passage upstream of the intercooler, The internal combustion engine control device includes: Determining whether a compressor rotation speed, which is the rotation speed of the compressor, is higher than a judgment rotation speed; When it is determined that condensation occurs at the joining portion, and when it is determined that the internal combustion engine is operating at a high load, and further when it is determined that the compressor rotation speed is higher than the judgment rotation speed, a cooling efficiency of the EGR gas by the EGR cooler is reduced compared to when it is determined that the compressor rotation speed is equal to or lower than the judgment rotation speed. The internal combustion engine control device according to claim 1.

3. The internal combustion engine control device includes: When it is determined that condensation occurs at the joining portion, and when it is determined that the internal combustion engine is operating at a high load, and when it is determined that the compressor rotation speed is equal to or lower than the determination rotation speed, the amount of condensation water collected by the collection device is reduced. The internal combustion engine control device according to claim 2.

4. The internal combustion engine control device includes: determining whether condensation water is generated in the intake passage due to cooling by the intercooler; When it is determined that no condensation water is generated at the joining portion and that condensation water is generated in the intake passage due to cooling by the intercooler, and when it is determined that the internal combustion engine is not operating at a high load, the cooling efficiency of the EGR gas by the EGR cooler is increased compared to when it is determined that the internal combustion engine is operating at a high load. The internal combustion engine control device according to claim 2 or 3.

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