JP2015124672A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve intake efficiency while suppressing the production of condensed water in an intake system.SOLUTION: An engine 10 includes an engine body 12, a high-temperature system intake passage 14A, a low-temperature system intake passage 14B, a high-temperature system intercooler 42, a low-temperature system intercooler 44, and a selector valve 58. The high-temperature system intercooler 42 and the low-temperature system intercooler 44 are arranged in parallel in an intake passage 14. When a low-temperature system water temperature Tw_cold is not higher than a temperature determination value β, the selector valve 58 closes the low-temperature system intake passage 14B so that intake air is distributed only into the high-temperature system intercooler 42 to suppress the production of condensed water. When the low-temperature system water temperature Tw_cold is higher than the temperature determination value β, the intake air is distributed into the two intercoolers 42, 43 in parallel to reduce pressure loss while cooling the intake air.

Description

  The present invention relates to an internal combustion engine used for an automobile or the like, and more particularly to an internal combustion engine provided with an intercooler and an EGR mechanism.

  As a conventional technique, for example, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-2223038), a system including a high temperature side heat exchanger and a low temperature side heat exchanger is known. In the prior art system, a low temperature side heat exchanger is provided downstream of the high temperature side heat exchanger, and the high temperature side heat exchanger and the low temperature side heat exchanger are arranged in series with respect to the flow direction of the intake air. . The system also includes a bypass passage for the intake air that has passed through the high temperature side heat exchanger to bypass the low temperature side heat exchanger, and a variable mechanism that changes the flow passage area of the bypass passage. In the prior art, the intake air temperature is controlled by adjusting the amount of intake air that bypasses the low temperature side heat exchanger.

JP 2010-223038 A JP 2010-249129 A

  In the above-described prior art, after the intake air passes through the high temperature side heat exchanger, it further passes through the low temperature side heat exchanger or passes through the bypass passage. However, when the intake air flows through the high temperature side heat exchanger and the low temperature side heat exchanger, the pressure loss increases due to the intake resistance. Even when the intake air that has passed through the high-temperature side heat exchanger flows through the bypass passage, the intake air passes through the side of the low-temperature side heat exchanger that protrudes into the passage and flows into the narrow bypass passage. Increase. For this reason, in the prior art, there is a problem that the intake efficiency and the engine performance tend to decrease.

  On the other hand, in an internal combustion engine equipped with a supercharger or an EGR mechanism, there is a demand for suppressing the amount of condensed water generated in the intake system. On the other hand, although the prior art system can control the intake air temperature to some extent, it does not consider the condensed water generated in the intake system. For this reason, even if the system of the prior art is applied to the internal combustion engine as described above, there is a problem that it is difficult to suppress the generation of condensed water.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an internal combustion engine capable of improving the suction efficiency while suppressing the generation of condensed water in the intake system. It is to provide.

  According to a first aspect of the present invention, a first intake passage capable of sucking intake air into the engine main body, and the engine main body connected in parallel to the first intake passage and sucking intake air into the engine main body A second intake passage capable of cooling, the high-temperature intercooler provided in the first intake passage, cooling the intake air flowing through the first intake passage, and sharing the refrigerant with the engine body, A low-temperature intercooler that is provided in the second intake passage and is arranged in parallel with the high-temperature intercooler, cools the intake air flowing through the second intake passage, and intake air that flows into the high-temperature intercooler. Changing means for changing the ratio of the amount of intake air flowing into the low-temperature intercooler.

  According to a second aspect of the invention, the changing means includes a switching valve that opens and closes at least the second intake passage of the first and second intake passages.

  According to a third aspect of the invention, the changing means includes a high temperature switching valve for opening and closing the first intake passage and a low temperature switching valve for opening and closing the second intake passage.

  According to a fourth aspect of the present invention, when the temperature of the cooling medium flowing through the low-temperature system intercooler is equal to or lower than a predetermined determination temperature, the change means shuts off the intake air flowing into the low-temperature system intercooler and Low temperature control means is provided for allowing intake air to flow only into the system intercooler.

  According to a fifth aspect of the present invention, when the temperature of the cooling medium flowing through the low temperature system intercooler is higher than a preset determination temperature, the change means takes in the intake air to both the high temperature system intercooler and the low temperature system intercooler. It is provided with a high temperature control means for injecting water.

  According to a sixth aspect of the present invention, when the temperature of the cooling medium flowing through the low-temperature system intercooler is higher than a preset determination temperature, the change means shuts off the intake air flowing into the high-temperature system intercooler and High temperature control means is provided for allowing intake air to flow only into the system intercooler.

  According to the seventh invention, the determination temperature is changed based on at least one of the temperature and humidity of the outside air.

The eighth invention comprises an EGR mechanism for recirculating exhaust gas in the first and second intake passages,
The determination temperature is changed based on the recirculation amount of the exhaust gas.

  According to the ninth invention, the high-temperature intercooler and the low-temperature intercooler are connected via a heat conductive material.

  According to the first aspect of the invention, the high-temperature intercooler and the low-temperature intercooler can be selectively used by the changing means according to the operating state of the internal combustion engine, the temperature environment, and the like. Accordingly, pressure loss during intake can be reduced while coping with the generation of condensed water, and the performance of the internal combustion engine can be improved.

  According to the second invention, for example, when the temperature is low, the intake air can be circulated only to the high-temperature intercooler by the switching valve, and the generation of condensed water inside the low-temperature intercooler can be suppressed.

  According to the third invention, either one of the high-temperature intercooler and the low-temperature intercooler can be used alternatively based on the operating state of the internal combustion engine, the temperature environment, and the like.

  According to the fourth aspect of the invention, the intake gas can be circulated only to the high-temperature intercooler during warm-up operation where the temperature of the low-temperature intercooler is low. Thereby, it can suppress that condensed water generate | occur | produces inside a low temperature type | system | group intercooler.

  According to the fifth aspect of the invention, during normal operation after completion of warm-up, a large amount of intake air can be efficiently cooled by using both the high-temperature intercooler and the low-temperature intercooler. The flow path area can be increased to reduce pressure loss due to the intercooler.

  According to the sixth aspect of the invention, the high-temperature intercooler need not be used during operation when the temperature of the high-temperature intercooler is high. Therefore, the intake gas can be efficiently discharged using only the low-temperature intercooler. Can be cooled.

  According to the seventh aspect, the determination temperature can be set to an appropriate value based on at least one of the outside air temperature and the outside air humidity. In other words, the high-temperature intercooler and the low-temperature intercooler can be properly used based on the temperature environment of the internal combustion engine. Therefore, it is possible to prevent any intercooler from being used in an inappropriate temperature region, and to stably prevent generation of condensed water and increase in pressure loss.

  According to the eighth aspect of the present invention, it is possible to reflect the ease of generation of condensed water due to the exhaust gas recirculation amount (EGR gas amount) in the determination temperature, and to appropriately determine the determination temperature based on the execution state of the EGR control. Can be set to any value.

  According to the ninth aspect of the invention, during high-power operation such as WOT, the heat of the high-temperature intercooler can be released to the low-temperature intercooler via the heat conductive material, and the high-temperature intercooler can be cooled. Further, when the water temperature is low, the low-temperature intercooler can be heated by the high-temperature intercooler whose temperature rises quickly, and the temperature rise performance of the low-temperature intercooler can be improved. In addition, the heat conduction speed between the intercoolers can be appropriately adjusted according to the heat conductivity of the heat conducting material so that the cooling effect and the temperature rising effect are maximized.

It is a block diagram for demonstrating the system configuration | structure of the engine by Embodiment 1 of this invention. It is a block diagram which shows the control system of an engine. It is explanatory drawing which shows the area | region where condensed water is easy to generate | occur | produce in the driving | running area | region of an engine. In Embodiment 1 of this invention, it is a timing chart which shows an example of switching valve control. In Embodiment 1 of this invention, it is a characteristic diagram which shows the relationship between external temperature and determination temperature. It is a characteristic diagram which shows the relationship between external air humidity and determination temperature. It is a characteristic diagram which shows the relationship between EGR gas amount and determination temperature. In Embodiment 1 of this invention, it is a flowchart which shows an example of the control performed by ECU. It is a block diagram for demonstrating the system configuration | structure of the engine by Embodiment 2 of this invention. In Embodiment 2 of this invention, it is a flowchart which shows an example of the control performed by ECU. In Embodiment 3 of this invention, it is sectional drawing which shows the structural example of an intercooler unit.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. It is a block diagram for demonstrating the system configuration | structure of the engine by Embodiment 1 of this invention. As shown in this figure, the system of the present embodiment includes an engine 10 that is an internal combustion engine with a supercharger. The engine 10 includes an engine body 12 provided with one or a plurality of cylinders, an intake passage 14 for sucking intake air into the cylinders of the engine body 12, and an exhaust passage 16 for discharging exhaust gas from the cylinders.

  At least part of the intake passage 14 is constituted by a high-temperature intake passage 14A and a low-temperature intake passage 14B that are branched from each other and connected in parallel. In the present embodiment, the high temperature intake passage 14A corresponds to the first intake passage, and the low temperature intake passage 14B corresponds to the second intake passage. The high temperature system intake passage 14 </ b> A and the low temperature system intake passage 14 </ b> B are connected to the engine body 12 in parallel to each other. In addition, a throttle valve 18 that adjusts the amount of intake air is provided in an upstream portion 14C that is upstream of the high-temperature intake passage 14A and the low-temperature intake passage 14B. On the other hand, a catalyst 20 for purifying exhaust gas is disposed in the exhaust passage 16.

  Further, the engine 10 is equipped with an EGR mechanism 22 constituting an LPL-EGR system. The EGR mechanism 22 recirculates a part of the exhaust gas as EGR gas to the intake passage 14, and includes an EGR passage 24, an EGR valve 26, an EGR cooler 28, and the like. One end side of the EGR passage 24 is connected to the exhaust passage 16 on the downstream side of the catalyst 20. The other end side of the EGR passage 24 is connected to the upstream portion 14C of the intake passage 14 on the upstream side of a supercharger 30 described later. The EGR valve 26 adjusts the recirculation amount (EGR gas amount) of the exhaust gas to the intake passage 14, and the EGR cooler 28 cools the EGR gas.

  The engine 10 is equipped with a turbo-type supercharger 30. The supercharger 30 includes a turbine provided in the exhaust passage 16 and a compressor provided in the upstream portion 14C of the intake passage 14. When the supercharger 30 is operated, the turbine is rotated by receiving the exhaust pressure to drive the compressor, and the compressor supercharges the intake air.

  Next, the cooling system of the engine 10 will be described. The engine 10 includes an intercooler unit 40, radiators 46 and 52, pumps 50 and 56, a switching valve 58, and the like. The intercooler unit 40 is an integrated unit of a high temperature system intercooler 42 provided in the high temperature system intake passage 14A and a low temperature system intercooler 44 provided in the low temperature system intake passage 14B. This embodiment is characterized in that the high-temperature intercooler 42 and the low-temperature intercooler 44 are arranged in parallel. In the following description, “intercooler” may be abbreviated as “I / C”.

  The high temperature system I / C 42 performs heat exchange between cooling water as a cooling medium supplied from the high temperature system radiator 46 and intake air flowing through the high temperature system intake passage 14A (hereinafter referred to as high temperature system intake air). As a result, the high-temperature intake air is cooled. The high-temperature system I / C 42 has, for example, a configuration substantially similar to that of a conventional intercooler, and includes a core (not shown) in which cooling water passages through which cooling water as a refrigerant flows and heat radiation fins are alternately stacked. ing. The cooling water passage of the high temperature system I / C 42 and the high temperature system radiator 46 are connected to each other via a circulation pipe 48. The circulation pipe 48 is provided with a high temperature system pump 50 that circulates cooling water between the high temperature system I / C 42 and the high temperature system radiator 46. The circulation pipe 48 is also connected to the cooling water passage of the engine body 12. The high temperature system radiator 46 cools the high temperature system intake air with the cooling water, and shares the cooling water used for the cooling with the engine body 12.

  The low temperature system I / C 44 performs cooling by exchanging heat between the cooling water supplied from the low temperature system radiator 52 and the intake air flowing through the low temperature system intake passage 14B (hereinafter referred to as low temperature system intake air). This cools the low-temperature intake air using water. The low temperature system I / C 44 is configured by a general intercooler having a core, almost the same as the high temperature system I / C 42. However, since the thermal load of the high temperature system I / C 42 is the engine body 12 and the intake system, the thermal load of the low temperature system I / C 44 is only the intake system, so the temperature of the low temperature system I / C 44 is the high temperature system I. The temperature is kept lower than / C42. The cooling water passage of the low temperature system I / C 44 is connected to the low temperature system radiator 52 via the circulation pipe 54. The low-temperature system radiator 52 is used only for cooling the intake air. The circulation pipe 54 is provided with a low temperature system pump 56 that circulates cooling water between the low temperature system I / C 44 and the low temperature system radiator 52.

  The switching valve 58 is configured by an electromagnetically driven butterfly valve or the like, and is provided in the low temperature system intake passage 14B on the upstream side of the low temperature system I / C 44. The switching valve 58 constitutes changing means for changing the ratio of the amount of high temperature system intake air and the amount of low temperature system intake air, and can open and close the low temperature system intake passage 14B. In the state where the switching valve 58 is fully closed, the flow of the intake air flowing into the low temperature system I / C 44 is blocked.

  Next, the control system of the system will be described with reference to FIG. FIG. 2 is a block diagram showing an engine control system. As shown in this figure, the engine 10 includes a sensor system including sensors 60 to 66 and an ECU (Electronic Control Unit) 70 that controls the engine 10. First, the sensor system will be described. The crank angle sensor 60 outputs a signal synchronized with the rotation of the crankshaft of the engine 10, and the air flow sensor 62 detects the intake air amount of the engine 10. The high temperature system water temperature sensor 64 detects the high temperature system water temperature Tw_hot which is the temperature of the cooling water flowing through the high temperature system I / C 42, and the low temperature system water temperature sensor 66 is the temperature of the cooling water flowing through the low temperature system I / C 44. The low temperature water temperature Tw_cold is detected.

  The ECU 70 includes an arithmetic processing circuit, a storage circuit, and an input / output port, and each sensor of the sensor system is connected to the input side of the ECU 70. Various actuators including a throttle valve 18, an EGR valve 26, pumps 50 and 56, and a switching valve 58 are connected to the output side of the ECU 70 in addition to the fuel injection valve and the spark plug of each cylinder. The ECU 70 calculates the engine speed, load, etc. based on the outputs of the crank angle sensor 60 and the airflow sensor 62, and controls the fuel injection amount, fuel injection timing, ignition timing, etc. based on the calculation results. Thus, the engine 10 is operated. Further, the ECU 70 executes EGR control that controls the amount of EGR gas based on the operating state of the engine 10 by driving the EGR valve 26.

[Features of Embodiment 1]
In general, an engine with a supercharger is required to be equipped with a low temperature system I / C in addition to a high temperature system I / C to efficiently cool the supercharged intake air. However, when the low-temperature system I / C is mounted, there is a problem that the pressure loss of the intake passage is likely to increase, and the generation of condensed water is induced at a cold start or the like. In particular, for example, in an engine (supercharged lean EGR engine) that supercharges intake air and recirculates EGR gas while burning the air-fuel mixture in a lean state, a mixed gas of a large amount of supercharged air and EGR gas Moisture contained therein is condensed in the intake passage, and a large amount of condensed water is likely to be generated. In order to solve such a problem, in this embodiment, the high-temperature system I / C 42 and the low-temperature system I / C 44 are arranged in parallel, and the amount of intake air flowing through these I / C 42 and 44 is set. It is set as the structure controlled according to the driving | running state of the engine 10. FIG. Hereinafter, a specific example of this control will be described.

  FIG. 3 is an explanatory diagram showing a region where condensed water is likely to be generated in the engine operation region. In this figure, the EGR control is executed in a state where the engine speed is low to the intermediate speed and the boost pressure is not so high in the operation region A where the torque (load) is an intermediate load. For this reason, in the operation region A, a large amount of EGR gas introduced from the EGR passage 24 and the intermediate-temperature air that is hardly compressed are mixed in the intake passage 14, and the temperature of the mixed gas is increased. Is less than the dew point temperature and condensate is likely to be generated. In contrast, in the high load operation region B, the EGR control is suppressed or stopped to reduce the amount of EGR gas, and the supercharging pressure (soot gas temperature) increases. It is hard to generate water. Further, even in the low load operation region C, the EGR control is suppressed or stopped, so that condensed water is hardly generated. On the other hand, in the operation region D where the rotation speed is high, the flow rate of the gas flowing through the intake passage 14 is increased, and the condensed water is blown away without accumulating, so that the same state as in the case where the condensed water is hardly generated is obtained.

  As described above, when EGR control is executed, condensed water is likely to be generated. Therefore, in the present embodiment, switching is performed based on the ease of generation of condensed water when the operating condition under which EGR control can be executed is satisfied. The switching valve control described later for controlling the valve 58 is executed. More specifically, when the high-temperature water temperature Tw_hot is higher than the preset warm-up determination temperature α, the switching valve control is executed. Here, the warm-up determination temperature α is set in correspondence with, for example, a warm-up state at which EGR control can be executed. The warm-up determination temperature α may be changed based on the operating state of the engine 10, the temperature environment, and the like.

(Switching valve control)
Next, the switching valve control according to the present embodiment will be described with reference to FIG. FIG. 4 is a timing chart showing an example of switching valve control in Embodiment 1 of the present invention. First, when the engine 10 is stopped, the switching valve 58 is held in the closed position, and the low temperature system intake passage 14B is closed. When cranking is performed in this state, intake air is supplied to the engine body 12 via the high temperature system intake passage 14A, and the engine 10 is started.

  The ECU 70 drives the high temperature pump 50 when the engine 10 is started. As a result, cooling water is circulated between the engine main body 12, the high temperature system I / C 42 and the high temperature system radiator 46 via the circulation pipe 48, and the high temperature system water temperature Tw_hot is, as shown in FIG. It gradually rises by absorbing the heat generated in When the high-temperature water temperature Tw_hot exceeds the warm-up determination temperature α, the EGR operation permission flag is set to “ON”, and the EGR control is permitted.

  On the other hand, the ECU 70 holds the low temperature system pump 56 in a stopped state until the low temperature system water temperature Tw_cold exceeds the determination temperature β. As a result, only the heat of the engine body 12 is transmitted to the cooling water on the low temperature system I / C 44 side via the vehicle body or the like, and the low temperature system water temperature Tw_cold rises more slowly than the high temperature system water temperature Tw_hot. At this time, the ECU 70 keeps the switching valve 58 in a closed state until the low-temperature water temperature Tw_cold exceeds the determination temperature β. Here, the determination temperature β is set according to the upper limit value of the temperature of the low temperature system I / C 44 that generates condensed water when the intake gas flows into the low temperature system I / C 44. Corresponds to dew point temperature. In the present invention, the determination temperature β may be a predetermined constant value or may be changed based on various parameters as will be described later.

  As described above, in the switching valve control, when the low-temperature system water temperature Tw_cold is equal to or lower than the determination temperature β, the intake valve flowing into the low-temperature system I / C 44 is blocked by the switching valve 58 and the temperature is relatively high. Low temperature control is performed in which the intake gas flows into only the I / C 42. The intake gas means intake air or a mixed gas of intake air and EGR gas. According to the low temperature control, when the temperature of the low temperature system I / C 44 is low, intake gas can be supplied to the engine body 12 from the high temperature system intake passage 14A. Thereby, even when the EGR control is executed in a low temperature state, it is possible to suppress the generation of condensed water in the low temperature system I / C 44 and the like, and the EGR control execution region can be expanded to the low temperature side. .

  Further, when the warm-up of the engine 10 proceeds and the low-temperature system water temperature Tw_cold exceeds the determination temperature β, it is considered that no condensed water is generated even if the intake gas flows into the low-temperature system I / C 44. Therefore, in the switching valve control, high temperature control for opening the switching valve 58 in such a case is executed. In the high temperature control, the low temperature pump 56 is driven to circulate cooling water to the low temperature system I / C 44. At this time, as shown in FIG. 4, the low temperature system water temperature Tw_cold may be controlled to a constant temperature by intermittently driving the low temperature system pump 56 based on the detection result of the low temperature system water temperature Tw_cold.

  When the high temperature control is executed, the intake gas flows into each of the high temperature system intake passage 14A and the low temperature system intake passage 14B, and flows through both the high temperature system I / C 42 and the low temperature system I / C 44 in parallel. Become. Therefore, during normal operation after completion of warm-up, a large amount of intake air can be efficiently cooled by using both the high temperature system I / C 42 and the low temperature system I / C 44. At this time, the flow area of the intake air is reduced. The pressure loss due to the intercooler can be reduced by increasing it.

  In particular, the volume (that is, the heat capacity) of the core of the high temperature system I / C 42 is made smaller than that of the low temperature system I / C 44, and the high temperature system I / C 42 is configured to quickly rise in temperature during cold start. Is preferred. However, with this configuration, the cross-sectional area of the high-temperature system I / C 42 is reduced and pressure loss is likely to increase. Therefore, during high load operation where the intake air amount increases, intake air is reduced only by the high-temperature system I / C 42. It becomes difficult to cool. In contrast, in the present embodiment, the pressure loss can be suppressed by the two parallel I / Cs 42 and 44 during high load operation while the core volume of the high-temperature system I / C 42 is sufficiently small. Therefore, it is possible to achieve both the temperature raising performance at the start and the operation performance at the time of high load.

  In the present embodiment, since the low temperature system I / C 44 is not used at the time of cold start, the core volume (cross-sectional area) of the low temperature system I / C 44 is preferably formed larger than that of the high temperature system I / C 42. . Thereby, even if the temperature rise performance of the low temperature system I / C 44 is somewhat lowered, the cooling performance of the low temperature system I / C 44 during high load operation or the like can be improved. The core volume and cross-sectional area ratio of the I / Cs 42 and 44 may be determined according to the required cooling performance and required pressure loss of each I / C. Here, the cross-sectional area is, for example, the cross-sectional area on a plane orthogonal to the flow direction of the intake gas. In the switching valve control, when switching from the low temperature control to the high temperature control, the switching valve 58 may be gradually opened as indicated by a virtual line in FIG. As a result, it is possible to avoid a sudden change in the flow of intake air at the time of control shift and instability of combustion or the like.

(Judgment temperature variable control)
In the present embodiment, the determination temperature variable control for changing the above-described determination temperature β based on at least one parameter among the outside air temperature, the outside air humidity, and the EGR gas amount may be executed. More specifically, the ECU 70 stores the characteristic line data shown in FIGS. 5 to 7 in advance as a data map or the like, and sets the determination temperature β based on the value of the parameter from the data map. It is good.

  Here, FIG. 5 to FIG. 7 are characteristic line diagrams individually showing the relationship between the outside air temperature, the outside air humidity, the EGR gas amount, and the judgment temperature in the first embodiment of the present invention. First, the influence of the outside air temperature will be described. The dew point temperature of water contained in the intake gas decreases as the outside air temperature (that is, the temperature of the intake air) increases. Therefore, the characteristic line shown in FIG. 5 is set such that the determination temperature β decreases as the outside air temperature increases. According to this setting, the higher the outside air temperature, the wider the temperature range for executing the high temperature control can be expanded to the low temperature side, and the low temperature system I / C 44 can be used from an early stage at the time of cold start or the like. .

  Next, the influence of outside air humidity will be described. The dew point temperature of water increases as the humidity of the intake air increases. Therefore, the characteristic line shown in FIG. 6 is set so that the determination temperature β increases as the outside air humidity increases. According to this setting, when the outside air humidity is low, the temperature range in which the high temperature control is executed can be expanded to the low temperature side. Next, the influence of the amount of EGR gas will be described. The moisture in the intake gas becomes easier to condense as the amount of humid EGR gas increases. Accordingly, the characteristic line shown in FIG. 7 is set such that the determination temperature β increases as the EGR gas amount (target amount of EGR gas set by EGR control) increases. According to this setting, it is possible to reflect the ease of generation of condensed water correlated with the amount of EGR gas in the determination temperature β, and when the amount of EGR gas is small, the temperature range in which the high temperature control is executed is set on the low temperature side. Can be expanded.

  As described above, according to the determination temperature variable control, the determination temperature β can be set to an appropriate value based on the values of the outside air temperature, the outside air humidity, and the EGR gas amount. That is, it is possible to accurately switch between the high temperature control and the low temperature control based on the operating state and temperature environment of the engine 10. Therefore, it is possible to stably prevent the pressure loss from being increased when the high temperature control is performed in an inappropriate temperature range and condensed water is generated or the low temperature control is not required. .

  In the determination temperature variable control, the determination temperature β may be set based on one or two parameters out of three parameters including the outside air temperature, the outside air humidity, and the EGR gas amount, or based on all the parameters. The determination temperature β may be set.

[Specific Processing for Realizing Embodiment 1]
Next, specific processing for realizing the above-described control will be described with reference to FIG. FIG. 8 is a flowchart showing an example of control executed by the ECU in the first embodiment of the present invention. The routine shown in this figure is repeatedly executed while the engine 10 is operating. In the routine shown in FIG. 8, first, in step 100, the high temperature system water temperature sensor 64 detects the high temperature system water temperature Tw_hot, and the low temperature system water temperature sensor 66 detects the low temperature system water temperature Tw_cold. Further, for example, the outside air temperature and the outside air humidity are detected by a temperature sensor, a humidity sensor, or the like.

  Next, in step 102, it is determined whether or not the high-temperature system water temperature Tw_hot is higher than the warm-up determination temperature α. Further, in step 104, it is determined whether or not an EGR required operation condition is satisfied. Here, the EGR required operation condition is, for example, whether or not the operation region of the engine 10 corresponds to the region A in FIG. If the determinations in steps 102 and 104 are both established, the routine proceeds to step 106 where EGR control is started and the EGR valve 26 is opened. If any of the determinations in steps 102 and 104 is not established, the process proceeds to step 114 described later.

  Next, in step 108, it is determined whether or not the low-temperature system water temperature Tw_cold is higher than the temperature determination value β. In this process, the temperature determination value β may be set by the above-described determination temperature variable control. If the determination at step 108 is established, the routine proceeds to step 110 where high temperature control is executed. That is, in step 110, the switching valve 58 is opened, and both the high temperature system intake passage 14A and the low temperature system intake passage 14B are opened.

  On the other hand, if the determination at step 108 is not established, the routine proceeds to step 112 where low temperature control is executed. That is, in step 112, the switching valve 58 is closed to open only the high temperature intake passage 14A and close the low temperature intake passage 14B. Then, after execution of steps 110 and 112, loop processing that repeats the processing of steps 104 to 112 is executed. If the determination in step 104 is not established during the loop processing, or if it is necessary to exit the loop processing due to other conditions, the routine proceeds to step 114 where the EGR valve 26 is closed and this routine is executed. Exit.

  As described above in detail, according to the present embodiment, the high temperature system I / C 42 and the low temperature system I / C 44 can be selectively used according to the operating state of the engine 10, the temperature environment, and the like. Therefore, pressure loss during intake can be reduced while coping with generation of condensed water, and engine performance can be improved. In the first embodiment, steps 108 and 110 shown in FIG. 8 show a specific example of the high temperature control means described in claim 5, and steps 108 and 112 correspond to the low temperature control described in claim 4. A specific example of the means is shown.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is characterized in that, in addition to the same configuration as that of the first embodiment, a switching valve is also arranged in the high temperature system intake passage. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 9 is a configuration diagram for explaining the system configuration of the engine according to the second embodiment of the present invention. The system of the present embodiment includes a high-temperature switching valve 80 that opens and closes the high-temperature intake passage 14A, and a low-temperature switching valve 82 that opens and closes the low-temperature intake passage 14B. The low temperature switching valve 82 is configured and arranged in the same manner as the switching valve 58 described in the first embodiment. The high temperature system switching valve 80 includes a butterfly valve similar to the switching valve 82, and is provided in the high temperature system intake passage 14A on the upstream side of the high temperature system I / C 42.

  In the present embodiment configured as described above, the control shown in FIG. 10 is executed. FIG. 10 is a flowchart showing an example of control executed by the ECU in the second embodiment of the present invention. The routine shown in this figure employs steps 210 and 212 in place of steps 110 and 112 of the routine described in the first embodiment (FIG. 8).

  Specifically, if it is determined in step 108 that the low-temperature system water temperature Tw_cold is higher than the temperature determination value β, the process proceeds to step 210, and the high-temperature control of the present embodiment is executed. That is, in step 210, the low temperature system switching valve 82 is opened, and the high temperature system switching valve 80 is closed. As a result, the inhaled gas is blocked from flowing into the high temperature system I / C 42 and flows only through the low temperature system I / C 44.

  On the other hand, if the determination in step 108 is not established, the process proceeds to step 212 and the low temperature control is executed. That is, in step 212, the low temperature system switching valve 82 is closed and the high temperature system switching valve 80 is opened. As a result, as in the case of the low temperature control described in the first embodiment, the intake gas does not flow through the low temperature system I / C 44 but only flows through the high temperature system I / C 42.

  In the present embodiment configured as described above, substantially the same effects as those of the first embodiment can be obtained. In particular, in the present embodiment, since the two switching valves 80 and 82 are provided, either one of the high temperature system I / C 42 and the low temperature system I / C 44 is selected based on the operating state of the engine 10 or the temperature environment. Can be used alternatively. Further, since the high temperature system I / C 42 is not used in the high temperature control, for example, even when the high temperature system water temperature Tw_hot becomes extremely high, the intake gas can be efficiently cooled using only the low temperature system I / C 44. Can do.

  In the second embodiment, steps 108 and 210 shown in FIG. 10 show a specific example of the high temperature control means described in claim 6, and steps 108 and 212 indicate the low temperature control described in claim 4. A specific example of the means is shown.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. This embodiment is characterized in that a heat conductive material is interposed between the high temperature system I / C and the low temperature system I / C. The present embodiment can be applied to both the first and second embodiments. Moreover, in this Embodiment, the same code | symbol shall be attached | subjected to the component same as Embodiment 1, and the description shall be abbreviate | omitted.

  FIG. 11 is a cross-sectional view showing a configuration example of an intercooler unit (I / C unit) in Embodiment 3 of the present invention. This sectional view is, for example, the I / C unit viewed from the direction of arrow XX in FIG. The system according to the present embodiment includes an I / C unit 90, and the I / C unit 90 includes a high-temperature system I / C 92 and a low-temperature system I / C 94 as in the first embodiment. Yes. The high temperature system I / C 92 includes a core 92A in which cooling water passages and heat radiation fins are alternately stacked, and a housing 92B that covers the core 92A from the outside. Similarly, the low temperature system I / C 94 includes the core 94A and the housing. 94B.

  The cross-sectional area of the core 94A of the low temperature system I / C 94 is formed larger than that of the core 92A of the high temperature system I / C 92. The cross-sectional area is, for example, the area of a cross section on a plane orthogonal to the flow direction of the intake gas. The two cores 92A and 94A are connected to each other through a flat plate-like heat conductive layer 96 made of a heat conductive material. Thereby, the heat of the high temperature system I / C 92 is configured to be conducted to the low temperature system I / C 94 at a speed corresponding to the thermal conductivity of the heat conductive layer 96.

  According to the present embodiment configured as described above, in addition to the effects of the first embodiment, the following effects can be obtained. First, during high-power operation such as WOT, the temperature of the cooling water circulating in the high-temperature system I / C 92 is also increased by the heat generated in the engine body 12. However, according to the I / C unit 90, the heat of the high temperature system I / C 92 can be released to the low temperature system I / C 94 via the heat conductive layer 96. Therefore, the high temperature system I / C 92 can be cooled using the low temperature system I / C 94 and the heat resistance of the engine 10 can be improved.

  Further, at the time of low water temperature, the low temperature system I / C 94 is heated by the high temperature system I / C 92 by utilizing the characteristic that the temperature of the high temperature system I / C 92 rises more rapidly than the low temperature system I / C 94 (see FIG. 4). be able to. As a result, the temperature raising performance of the low temperature system I / C 94 can be improved, and the low temperature control can be quickly switched to the high temperature control. Then, the heat conduction speed between the I / C 92 and 94 can be appropriately adjusted according to the heat conductivity of the heat conductive layer 96 so that the cooling effect and the temperature rising effect are maximized.

  In the first to third embodiments, the engine 10 including the EGR mechanism 22 and the supercharger 30 is illustrated. However, the present invention is not limited to this, and may be applied to an internal combustion engine not equipped with a supercharger. The present invention is not necessarily applied to an internal combustion engine equipped with an EGR mechanism, and can be widely applied to an internal combustion engine not equipped with an EGR mechanism as long as the system introduces a gas with high humidity into the intercooler. be able to.

  Moreover, in Embodiment 1, 2, the case where the switching valves 58, 80, and 82 which consist of a butterfly valve were used was illustrated. However, the present invention is not limited to this. For example, a three-way valve is provided at a branch portion of the high-temperature system intake passage 14A and the low-temperature system intake passage 14B. It is good also as a structure to implement | achieve.

10 Engine (Internal combustion engine)
12 Engine body 14 Intake passage 14A High-temperature intake passage (first intake passage)
14B Low-temperature system intake passage (second intake passage)
14C Upstream part 16 Exhaust passage 18 Throttle valve 20 Catalyst 22 EGR mechanism 24 EGR passage 26 EGR valve 30 Supercharger 40, 90 Intercooler units 42, 92 High temperature system intercooler 44, 94 Low temperature system intercooler 46 High temperature system radiator 50 High temperature System pump 52 Low temperature system radiator 56 Low temperature system pump 58, 80, 82 Switching valve (changing means)
64 High-temperature system water temperature sensor 66 Low-temperature system water temperature sensor 70 ECU
92A, 94A Core 92B, 94B Housing 96 Thermal conduction layer

Claims (9)

A first intake passage capable of sucking intake air into the engine body;
A second intake passage connected to the engine body in parallel with the first intake passage and capable of sucking intake air into the engine body;
A high-temperature intercooler that is provided in the first intake passage, cools intake air flowing through the first intake passage, and shares a refrigerant with the engine body;
A low-temperature intercooler that is provided in the second intake passage and is arranged in parallel with the high-temperature intercooler, and cools the intake air flowing through the second intake passage;
Change means for changing the ratio of the amount of intake air flowing into the high temperature system intercooler and the amount of intake air flowing into the low temperature system intercooler;
Internal combustion engine equipped with.   2. The internal combustion engine according to claim 1, wherein the changing unit includes a switching valve that opens and closes at least the second intake passage of the first and second intake passages.   2. The internal combustion engine according to claim 1, wherein the changing unit includes a high-temperature switching valve that opens and closes the first intake passage and a low-temperature switching valve that opens and closes the second intake passage.   When the temperature of the cooling medium flowing through the low-temperature system intercooler is equal to or lower than a preset determination temperature, the change means shuts off the intake air flowing into the low-temperature system intercooler and sucks only into the high-temperature system intercooler. The internal combustion engine according to any one of claims 1 to 3, further comprising low-temperature control means for introducing air.   When the temperature of the cooling medium flowing through the low-temperature system intercooler is higher than a preset determination temperature, the change means controls the high temperature control so that intake air flows into both the high-temperature system intercooler and the low-temperature system intercooler. The internal combustion engine according to any one of claims 1 to 4, further comprising means.   When the temperature of the cooling medium flowing through the low-temperature system intercooler is higher than a preset judgment temperature, the change means shuts off the intake air flowing into the high-temperature system intercooler and sucks only into the low-temperature system intercooler. The internal combustion engine according to any one of claims 1 to 4, further comprising high-temperature control means for introducing air.   The internal combustion engine according to any one of claims 4 to 6, wherein the determination temperature is configured to be changed based on at least one parameter of temperature and humidity of outside air. An EGR mechanism for recirculating exhaust gas in the first and second intake passages;
The internal combustion engine according to any one of claims 4 to 7, wherein the determination temperature is changed based on a recirculation amount of the exhaust gas.   The internal combustion engine according to any one of claims 1 to 8, wherein the high-temperature intercooler and the low-temperature intercooler are configured to be connected via a thermally conductive material.

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