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

[0005] , , , , , ,

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[0001] The present invention relates to an internal combustion engine control device applied to an internal combustion engine using gaseous fuel as fuel.

Background Art

[0002] Patent Document 1 discloses an internal combustion engine provided with an EGR device that recirculates a part of the exhaust gas discharged from the cylinder into the intake passage. The exhaust gas recirculated into the intake passage by the EGR device is referred to as "EGR gas". "EGR" is an abbreviation of "Exhaust Gas Recirculation".

[0003] The EGR device includes an EGR passage connected to the intake passage, an EGR cooler that cools the EGR gas flowing through the EGR passage, and a collection device that collects the condensed water generated in the EGR passage. The EGR passage includes an EGR cooler located upstream of the collection device, which cools the EGR gas flowing through the EGR passage, The EGR passage is connected to a portion of the intake passage upstream of the intercooler. And when the control device that controls the internal combustion engine determines that condensed water is generated in the intake passage due to cooling by the intercooler, it suppresses the generation of condensed water in the intake passage by reducing the cooling efficiency of the EGR gas by the EGR cooler. Thereby, the inflow of condensed water into the cylinder through the intake passage is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0006] An internal combustion engine control device for solving the above problems comprises a cylinder, an intake passage through which air 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 as EGR gas into the intake passage, and is applied to an internal combustion engine in which gaseous fuel is supplied into the cylinder. The EGR device is connected to the intake passage and comprises an EGR passage through which EGR gas flows toward the intake passage, and a collection device for collecting condensed water generated in the EGR passage. The internal combustion engine control device performs the following actions when EGR gas is introduced into the intake passage via the EGR passage: determine whether or not condensation is generated in the confluence portion of the intake passage, which is the part to which the EGR passage is connected; determine whether or not the internal combustion engine is operating under high load based on the rotational speed of the output shaft of the internal combustion engine and the output torque of the internal combustion engine; and, if it is determined that condensation is generated in the confluence portion of the intake passage and the internal combustion engine is operating under high load, reduce the amount of condensation collected by the collection device. [Effects of the Invention]

[0007] The above-described internal combustion engine control device has the effect of suppressing the rise in cylinder temperature when the internal combustion engine is operating under high load. [Brief explanation of the drawing]

[0008] [Figure 1]Figure 1 is a configuration diagram showing the internal combustion engine control device of the first embodiment and the internal combustion engine to which the internal combustion engine control device is applied. [Figure 2] Figure 2 is a map used to identify the operating range of the internal combustion engine shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing the processing routine executed by the internal combustion engine control device of the first embodiment. [Figure 4] Figure 4 is a configuration diagram showing the internal combustion engine control device of the second embodiment and the internal combustion engine to which the internal combustion engine control device is applied. [Figure 5] Figure 5 is a flowchart showing the first half of the processing routine executed by the internal combustion engine control device of the second embodiment. [Figure 6] Figure 6 is a flowchart showing the latter part of the processing routine executed by the internal combustion engine control device of the second embodiment. [Modes for carrying out the invention]

[0009] (First Embodiment) The first embodiment of the internal combustion engine control device will be described below with reference to Figures 1 to 3. Figure 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 the "internal combustion engine control device".

[0010] <Internal Combustion Engine> The internal combustion engine 10 comprises a plurality of cylinders 11, an intake passage 12, a plurality of fuel injection valves 13, and an exhaust passage 14. Each of the plurality of cylinders 11 houses a piston 15. Each of the plurality of pistons 15 is connected to a crankshaft 17 via a connecting rod 16. The crankshaft 17 rotates as the pistons 15 reciprocate within the plurality of cylinders 11. The crankshaft 17 corresponds to the "output shaft of the internal combustion engine 10".

[0011] The intake passage 12 is connected to multiple cylinders 11. The intake passage 12 is a passage through which air is introduced into the multiple cylinders 11. The intake passage 12 is equipped with an intercooler 18 to cool the air flowing through it. Downstream of the intercooler 18 in the intake passage 12, a throttle valve 19 is installed to adjust the amount of air introduced into the multiple cylinders 11.

[0012] Multiple fuel injectors 13 each inject gaseous fuel into the cylinder 11. One example of gaseous fuel is hydrogen gas. In the example shown in Figure 1, port injectors are shown as fuel injectors 13 that inject gaseous fuel into the intake passage 12 downstream of the throttle valve 19. The internal combustion engine 10 may also be equipped with in-cylinder injectors as fuel injectors 13 that directly inject gaseous fuel into the cylinder 11.

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

[0014] The internal combustion engine 10 is equipped with an EGR device 30. The EGR device 30 is a device that recirculates a portion 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 comprises an EGR passage 31, an EGR cooler 32, an EGR valve 34, and a collection device 35. The EGR passage 31 is a passage that allows the EGR gas to flow toward the intake passage 12. The first end of the EGR passage 31 is connected to the exhaust passage 14. The second end of the EGR passage 31 is connected to the intake passage 12. In the example shown in Figure 1, the second end of the EGR passage 31 is connected to the portion of the intake passage 12 between the intercooler 18 and the throttle valve 19. The portion of the intake passage 12 to which the EGR passage 31 is connected is also called the "merging portion".

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

[0016] The EGR valve 34 is installed in a portion of the EGR passage 31 that is 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 the EGR gas in the EGR passage 31. That is, the recirculation amount of the EGR gas to the intake passage 12 increases.

[0017] [[ID=,8]]The collection device 35 is arranged downstream of the EGR valve 34 in the EGR passage 31. The collection device 35 is arranged upstream of the connection portion of the EGR passage 31 with the intake passage 12. That is, the collection device 35 is installed so 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 be able to collect the condensed water generated in the EGR passage 31.

[0018] An example of the collection device 35 will be described. An 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 be able to adjust the distribution ratio of the EGR gas flowing through the EGR passage 31 that flows into the first passage. The collector collects the condensed water that has flowed into the first passage. In this collection device 35, the higher the distribution ratio, the higher the collection efficiency of the condensed water.

[0019] The internal combustion engine 10 includes an exhaust-driven supercharger 40. The supercharger 40 has a turbine 41 disposed in the exhaust passage 14 and a compressor 42 disposed in the intake passage 12. The turbine 41 is disposed downstream of the portion of the exhaust passage 14 to which the EGR passage 31 is connected. The compressor 42 is disposed upstream of the intercooler 18 in the intake passage 12. The turbine 41 operates by the flow of exhaust 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 includes 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 rotational speed of the crankshaft 17. The air flow meter 52 detects the amount of air flowing through the 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 rotational speed of the crankshaft 17 based on the signal of the crank angle sensor 51 is referred to as the "engine rotational speed NE". The air flow rate 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. By the CPU 101 executing the control program, the control device 100 can control the operation of the internal combustion engine 10. In the present embodiment, the control device 100 controls the EGR device 30 according to the operation region of the internal combustion engine 10.

[0023] Figure 2 shows a map for understanding the operating range of the internal combustion engine 10 based on engine speed NE and engine torque TQ. Engine torque TQ is the output torque of the internal combustion engine 10. The control device 100 calculates the engine torque TQ such that, for example, the value increases as the accelerator opening increases.

[0024] The operating range of the internal combustion engine 10 can be divided into three ranges: 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 the operating range where 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 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 the operating range where the engine load is moderate. When both the engine speed NE and engine torque TQ are moderate, 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 the operating range where the engine load is relatively high. When both the engine speed NE and 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 EGR gas into cylinder 11, the amount of fuel injected by the fuel injector 13 is reduced. As a result, the temperature inside cylinder 11 does not rise easily. Furthermore, by introducing condensed water generated in the EGR passage 31 into cylinder 11, the effect of suppressing the temperature rise inside cylinder 11 is further enhanced.

[0026] Even in the internal combustion engine 10 that uses 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, a 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, thereby stopping the recirculation of EGR gas into the intake passage 12 by the EGR device 30. After that, the control device 100 terminates this processing routine.

[0030] In step S21, the control device 100 performs a condensation determination process. In this determination process, the control device 100 calculates the first dew point TMPd1, which is the 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 such that the higher the temperature of the EGR passage 31, the higher the temperature of the first dew point TMPd1. The control device 100 calculates the first dew point TMPd1 such that the higher the humidity, the higher the temperature of the first dew point TMPd1. The control device 100 calculates the first dew point TMPd1 such that the higher the pressure, the higher the temperature of the first dew point TMPd1.

[0031] Furthermore, in the determination process, the control device 100 calculates the first gas temperature TMPg1, which is the temperature at the junction of the intake passage 12 with the EGR passage 31. The control device 100 calculates the first gas temperature TMPg1 based on the ambient temperature TMP, the temperature of the EGR gas that has passed through the EGR valve 34, the intake air volume GA, and the return flow rate of the EGR gas. If a sensor is provided to detect the temperature of the portion of the EGR passage 31 downstream of the EGR valve 34, the control device 100 can obtain the temperature of the EGR gas based on the detection signal of the sensor. The control device 100 can derive the return flow rate of the EGR gas such that the value increases as the opening degree of the EGR valve 34 increases. The control device 100 then calculates the first gas temperature TMPg1 such that the first gas temperature TMPg1 increases as the ambient temperature TMP increases. The control device 100 then calculates the first gas temperature TMPg1 such that the first gas temperature TMPg1 increases as the intake air volume GA decreases. The control device 100 calculates the first gas temperature TMPg1 such that the first gas temperature TMPg1 increases as the temperature of the EGR gas increases. The control device 100 also calculates the first gas temperature TMPg1 such that the first gas temperature TMPg1 increases as the return flow rate of the EGR gas increases.

[0032] Once the control device 100 has calculated the first dew point TMPd1 and the first gas temperature TMPg1, it proceeds to step S23. In step S23, the control device 100 determines whether or not condensation occurs at the confluence portion of the intake passage 12. For example, the control device 100 determines that condensation occurs if the first gas temperature TMPg1 is less than or equal to the first dew point TMPd1. On the other hand, the control device 100 determines that condensation does not occur if the first gas temperature TMPg1 is higher than the first dew point TMPd1. If the control device 100 determines that condensation occurs (S23: YES), it proceeds to step S31. On the other hand, if the control device 100 determines that condensation does not occur (S23: NO), it proceeds to step S25.

[0033] In step S25, the control device 100 controls the opening of the EGR valve 34 according to the requested EGR amount. The requested EGR amount is the requested amount of EGR gas to be returned to the intake passage 12 via the EGR passage 31. For example, the higher the load on the internal combustion engine 10, the larger the value set as the requested EGR amount. The control device 100 should operate the EGR valve 34 so that the opening degree increases as the requested EGR amount increases. Then, the control device 100 terminates this processing routine.

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

[0035] In step S33, the control device 100 performs a process to increase the amount of condensate collected by the collection device 35. Assume that the collection device 35 has the configuration described above. In this case, the control device 100 operates the switching valve so that the flow rate of EGR gas to the first passage where the collector is located increases compared to when the internal combustion engine 10 is operating under high load. Then, the control device 100 moves the process to step S25.

[0036] In step S35, the control device 100 performs a process to reduce the amount of condensate collected by the collection device 35. Assume that the collection device 35 has the configuration described above. In this case, the control device 100 operates the switching valve so that the flow rate of EGR gas to the first passage where the collector is located is reduced compared to when it is determined that the internal combustion engine 10 is not operating under high load. As a result, the control device 100 can reduce the amount of condensate collected by the collection device 35. Then, the control device 100 proceeds to step S25.

[0037] <Operation and Effects of This Embodiment> (1-1) The control device 100 determines whether or not condensation is generated at the above-mentioned confluence of the intake passage 12 when EGR gas is introduced into the intake passage 12 via the EGR passage 31 (S23). The control device 100 determines whether or not the internal combustion engine 10 is operating under high load (S31). If the control device 100 determines that condensation is generated at the above-mentioned confluence (S23: YES) and also determines that the internal combustion engine 10 is operating under 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 that flows into the intake passage 12 via the EGR passage 31 along with the EGR gas. The condensed water that flows into the intake passage 12 flows into multiple cylinders 11 along with the air and EGR gas. Inside the cylinders 11, the condensed water vaporizes due to the pressure increase inside the cylinders 11 caused by the combustion of the fuel-air mixture. At this time, the latent heat of vaporization of the condensed water suppresses the temperature rise inside the cylinders 11. Therefore, the control device 100 can suppress the temperature rise 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 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, if the control device 100 determines that condensate is generated at the above-mentioned confluence portion of the intake passage 12 (S23: YES) and that the internal combustion engine 10 is not operating under high load (S31: NO), it increases the amount of condensate 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. As a result, the adhesion of condensed water to the components of the internal combustion engine 10 is suppressed. Moreover, since the internal combustion engine 10 is not operating under high load, even if the amount of condensed water flowing into the cylinder 11 is reduced, the temperature rise inside the cylinder 11 is sufficiently suppressed by introducing EGR gas into the cylinder 11. Therefore, the control device 100 can suppress the temperature rise inside the cylinder 11 while suppressing the progression of changes in the characteristics of the components of the internal combustion engine 10.

[0041] (1-3) In the internal combustion engine 10, hydrogen is supplied as fuel to multiple cylinders 11. The ignition properties of hydrogen are higher than those of liquid fuels such as gasoline. Therefore, pre-ignition is likely to occur in the internal combustion engine 10. To suppress the occurrence of pre-ignition, it is preferable to keep the temperature inside the cylinders 11 from rising too high.

[0042] In this regard, the control device 100 is configured to introduce condensed water generated by cooling the EGR gas into multiple cylinders 11 when the internal combustion engine 10 is operating under high load. This suppresses the temperature rise 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 the internal combustion engine control device will be described with reference to Figures 4 to 6. In the second embodiment, the structure of the internal combustion engine to which the internal combustion engine control device is applied differs from that of the first embodiment. In the following description, the differences from the first embodiment will be mainly described, and the same reference numerals will be used for components identical to those in the first embodiment to avoid redundant explanations.

[0044] Figure 4 illustrates the internal combustion engine 10A installed in the vehicle and the control device 1000 to which the internal combustion engine 10A is applied. The control device 1000 corresponds to the "internal combustion engine control device". <Internal Combustion Engine> The internal combustion engine 10A, like the internal combustion engine 10, is equipped with multiple cylinders 11, an intake passage 12, an exhaust passage 14, and a supercharger 40. The internal combustion engine 10A is equipped with an EGR device 30A.

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

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

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

[0048] <Processing for controlling the EGR device> Referring to FIGS. 5 and 6, the 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 performs a first determination process for condensate. The first determination process is the same as the condensate determination process in step S21. Once the control device 1000 has calculated the first dew point TMPd1 and the first gas temperature TMPg1, it proceeds to step S63.

[0051] In step S63, the control device 1000 determines, in the same manner as in step S23, whether or not condensate is generated at the junction of the intake passage 12 with the EGR passage 31A. If the control device 1000 determines that condensate is generated at the junction (S63: YES), it proceeds to step S81. On the other hand, if the control device 1000 determines that condensate is not generated at the junction (S63: NO), it proceeds to step S65.

[0052] In step S65, the control device 1000 performs a second determination process for condensed water. In the second determination process, the control device 1000 calculates the second dew point TMPd2, which is the 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 referred to as "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 such 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 such 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 such that the higher the supercharge 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 the 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 the portion of the intake passage 12 downstream of the intercooler 18, the control device 1000 can calculate the second gas temperature TMPg2 based on the detection signal from the sensor.

[0054] Once the control device 1000 has calculated the second dew point TMPd2 and the second gas temperature TMPg2, it proceeds to step S67. In step S67, the control device 1000 determines whether or not condensation water is generated in the intake passage 12 due to the cooling of the pressurized gas by the intercooler 18. For example, the control device 1000 determines that condensation water is generated if the second gas temperature TMPg2 is less than or equal to the second dew point TMPd2. On the other hand, the control device 1000 determines that condensation water is not generated if the second gas temperature TMPg2 is higher than the second dew point TMPd2. If the control device 1000 determines that condensation water is generated (S67: YES), the process proceeds to step S71. On the other hand, if the control device 1000 determines that condensation water is not generated (S67: NO), the process proceeds to step S69.

[0055] In step S69, the control device 1000 controls the opening degree of the EGR valve 34 according to the requested EGR amount, similar to step S25 above. Then, the control device 1000 terminates this processing routine.

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

[0057] In step S73, the control device 1000 performs a process to increase 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 under high load, thereby increasing the cooling efficiency of the EGR cooler 32. After that, the control device 1000 proceeds to step S69.

[0058] In step S81, the control device 1000 determines whether the internal combustion engine 10A is operating under high load. If the control device 1000 determines that the internal combustion engine 10A is operating under high load (S81: YES), it proceeds to step S83. On the other hand, if the control device 1000 determines that the internal combustion engine 10A is not operating under high load (S81: NO), it can determine that the internal combustion engine 10A is operating under medium load, and therefore proceeds to step S69.

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

[0060] Here, if the compressor rotation speed NC is high, there is a risk that the blades of the compressor 42 may be damaged when water droplets that flow into the compressor 42 collide with them. On the other hand, if the compressor rotation speed NC is relatively low, the blades of the compressor 42 will not be damaged even if water droplets that flow into the compressor 42 collide with them. Therefore, it is desirable to set the compressor rotation speed NCth as the judgment rotation speed such that the blades of the compressor 42 are not damaged by the water droplets when condensed water is introduced into the compressor 42.

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

[0062] In step S85, the control device 1000 performs a process to reduce the cooling efficiency of the EGR gas by the EGR cooler 32 compared to the case where the compressor rotation speed NC is determined to be less than or equal to 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 is generated by the cooling of the pressurized gas by the intercooler 18, while suppressing the generation of condensation at the above-mentioned confluence portion of the intake passage 12. After that, the control device 1000 proceeds to step S69.

[0063] In step S87, the control device 1000 performs a process to reduce the amount of condensate collected by the collection device 35, similar to the process in step S35. Then, the control device 1000 proceeds to step S69.

[0064] <Operation and Effects of This Embodiment> In this embodiment, in addition to the effects and benefits (1-2) and (1-3) of the first embodiment described above, the following effects can be further obtained.

[0065] (2-1) The control device 1000 determines whether or not condensation is generated at the above-mentioned confluence of the intake passage 12 when EGR gas is introduced into the intake passage 12 via the EGR passage 31A (S63). The control device 1000 determines whether or not the internal combustion engine 10A is operating at a high load (S81). If the control device 1000 has determined that condensation is generated at the confluence of the intake passage 12 (S63: YES), and has determined that the internal combustion engine 10A is operating at a high load (S81: YES), and has further determined that the compressor rotation speed NC is less than or equal to the determined rotation speed NCth (S83: NO), then the amount of condensation collected by the collection device 35 is reduced (S87).

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

[0067] (2-2) As described above, if the compressor rotation speed NC is higher than the determination rotation speed NCth, the condensed water generated at the confluence of the intake passage 12 may flow into the compressor 42 and potentially damage the components of the compressor 42. Therefore, if the control device 1000 determines that condensed water is generated at the confluence of the intake passage 12 (S63:YES), and that the internal combustion engine 10A is operating under high load (S81:YES), and further determines that the compressor rotation speed NC is higher than the determination rotation speed NCth (S83:YES), it reduces the cooling efficiency of the EGR gas by the EGR cooler 32.

[0068] This suppresses the generation of condensed water at the confluence of the intake passage 12. As a result, when the compressor rotation speed NC is relatively high, the inflow of condensed water into the compressor 42 is suppressed. 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 is generated in the intake passage 12 by the cooling of the pressurized gas by the intercooler 18, while suppressing the generation of condensation at the confluence of the intake passage 12. As a result, even when the compressor rotation speed NC is higher than the determination rotation speed NCth, the control device 1000 can supply the condensation generated in the intake passage 12 by the cooling of the pressurized gas by the intercooler 18 into multiple cylinders 11. Therefore, the control device 1000 can protect the components of the compressor 42 while suppressing the temperature rise inside the cylinders 11 during high-load operation of the internal combustion engine 10A.

[0070] (2-3) The control device 1000 determines that no condensate is generated at the above-mentioned confluence portion of the intake passage 12 (S63: NO), and determines that condensate is generated in the intake passage 12 due to the 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), and increases the cooling efficiency of the EGR gas by the EGR cooler 32 compared to the case where the internal combustion engine 10A is operating under high load.

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

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

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

[0074] <Example of changes> The above-described embodiments can be implemented with the following modifications. The above-described embodiments and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0075] In the second embodiment described above, if the control device 1000 determines that condensed water is generated in the intake passage 12 due to the cooling of pressurized gas by the intercooler 18 (S67: YES), it 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 described above, if the control device 1000 determines that condensate is generated at the confluence portion of the intake passage 12 (S63:YES), and that the internal combustion engine 10A is operating under high load (S81:YES), and further determines that the compressor rotation speed NC is less than or equal to the determined rotation speed NCth (S83:NO), then it is not necessary to reduce the amount of condensate collected by the collection device 35.

[0077] In the first embodiment described above, the internal combustion engine 10 may be an internal combustion engine without a supercharger 40. In this case, the intake passage 12 does not need to be provided with an intercooler 18.

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

[0079] (a) The control devices 100,1000 each include one or more processors that perform various processes according to a computer program. The processors include a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform processes. The memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer.

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

[0081] (c) The control devices 100,1000 include a processor that executes a portion of the various processes according to a computer program, and dedicated hardware circuits that execute the remaining processes of the various processes.

[0082] In this specification, the expression "at least one" means "one or more" of the desired options. For example, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, if there are three or more options, the expression "at least one" means "only one option" or "a combination of two or more arbitrary options." [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 is applied to an internal combustion engine that comprises a cylinder, an intake passage through which air 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 as EGR gas into the intake passage, and gaseous fuel is supplied into the cylinder, The EGR device comprises an EGR passage connected to the intake passage and through which EGR gas flows toward the intake passage, a collection device for collecting condensed water generated in the EGR passage, and an EGR cooler located upstream of the collection device in the EGR passage and for cooling the EGR gas flowing through the EGR passage. The aforementioned collection device, A first passage and a second passage arranged in parallel to each other, A collector placed in the first passage, A switching valve that can adjust the collection efficiency of condensed water by adjusting the distribution ratio of the EGR gas flowing through the first passage, It has the following characteristics: The aforementioned internal combustion engine control device is When EGR gas is introduced into the intake passage via the EGR passage, it is determined whether or not condensation occurs in the confluence portion of the intake passage, which is the part to which the EGR passage is connected. Based on the rotational speed of the output shaft of the internal combustion engine and the output torque of the internal combustion engine, it is determined whether or not the internal combustion engine is operating under high load. If it is determined that condensation is generated in the confluence portion of the intake passage, and that the internal combustion engine is operating under high load, then the amount of condensation collected by the collection device is reduced. Internal combustion engine control device.

2. The aforementioned internal combustion engine is A supercharger comprising a turbine provided in the exhaust passage, and a compressor provided in the intake passage that operates in synchronous manner with the turbine, The intake passage is located downstream of the compressor and includes an intercooler that cools the air flowing through the intake passage. The aforementioned confluence section is located in the intake passage upstream of the compressor. The aforementioned internal combustion engine control device is The process involves determining whether the compressor rotation speed, which is the rotational speed of the compressor, is higher than the determination rotation speed. When it is determined that condensed water is generated at the aforementioned confluence, and it is determined that the internal combustion engine is operating under high load, and further, it is determined that the compressor rotation speed is higher than the determined rotation speed, the cooling efficiency of the EGR gas by the EGR cooler is reduced compared to when it is determined that the compressor rotation speed is less than or equal to the determined rotation speed. The internal combustion engine control device according to claim 1.

3. The aforementioned internal combustion engine control device is If it is determined that condensate is generated at the aforementioned confluence point, and that the internal combustion engine is operating under high load, and further determined that the compressor rotation speed is below the predetermined rotation speed, then the amount of condensate collected by the collection device will be reduced. The internal combustion engine control device according to claim 2.

4. The aforementioned internal combustion engine control device is To determine whether or not condensation water is generated in the intake passage due to cooling by the intercooler, When it is determined that no condensation is generated at the aforementioned confluence point, and when it is determined that condensation is generated in the intake passage due to cooling by the intercooler, and further when it is determined that the internal combustion engine is not operating under 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 under high load. The internal combustion engine control device according to claim 2 or claim 3.

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