JP2019190323A - Cooling system - Google Patents

Abstract

To further suitably warm up an engine, and to cool an EGR gas, in a cooling system having a cooling system of an intake system of the engine and a cooling system of an engine main body.SOLUTION: In a cooling system CS related to one embodiment of this disclosure, a first cooling system C1 and a second cooling system C2 in which cooling water circulates are integrally formed. A first bypass passage 55 of first cooling means 54 and an exhaust cooling device 46 are arranged in the first cooling system C1. Second cooling means in which the cooling water of an engine main body can circulate is arranged at the second cooling system C2. Furthermore, a first valve 56 for adjusting a cooling water flow rate of the first bypass passage and a cooling water flow rate of the first cooling means, an intake air cooling passage of the first cooling system connected to an EGR cooler 46, a second valve 72 for adjusting communication with the second cooling system, and a pump 70 for making the cooling water of the first and second cooling systems circulate are arranged.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a cooling system configured to include a cooling system for an intake system of an engine and a cooling system for an engine body.

  Patent Document 1 discloses an example of a cooling system configured to include an engine intake system cooling system and an engine body cooling system. In Patent Document 1, a water pump and a high temperature heat exchanger are provided in a main circuit corresponding to a cooling system of an engine body, and a low temperature heat exchanger is provided in a low temperature circuit corresponding to a cooling system of an intake system of the engine. In the main circuit, the thermostat is closed during the warm-up operation, and the cooling water flowing into the main circuit from the engine is supplied to the engine without passing through the high-temperature heat exchanger. In the low-temperature circuit, the cooling water that flows in from the main circuit downstream of the water pump flows through the intake air cooler that cools the intake air of the engine, specifically the intercooler and the EGR cooler, and then the upstream side of the water pump. To join the main circuit. Furthermore, in one embodiment of Patent Document 1, the EGR cooler is configured to be multi-stage cooled by both the cooling water of the main circuit and the cooling water of the low-temperature circuit.

JP 2006-50545 A

  By the way, in the EGR cooler, when the EGR gas is excessively cooled, moisture in the EGR gas is condensed and condensed water is generated. When such condensed water contains nitrogen oxide in EGR gas, for example, the nitrogen oxide dissolves to form an acid, which may shorten the life of the piping of the intake system. On the other hand, in recent years, there has been an increasing demand for improving the environmental performance of vehicles. For example, it is desirable to perform engine warm-up more favorably by circulating cooling water in a cooling system mounted on the vehicle. It is.

  In the cooling system configured to have a cooling system of an intake system of an engine and a cooling system of an engine body, the technology of the present disclosure allows a cooling medium such as cooling water to flow more suitably in the cooling system, and It is an object to more suitably perform warm-up and cooling of the EGR gas, that is, cooling of the exhaust gas recirculated from the engine exhaust system to the intake system.

  In order to achieve the above object, the technology of the present disclosure is a first cooling system, and includes a first cooling means for cooling a cooling medium, a first bypass passage that bypasses the first cooling means, and an intake air A first cooling system including an exhaust cooling device configured to cool the exhaust gas recirculated from the exhaust system of the engine to the intake system, and the first cooling system. A second cooling system configured integrally with the cooling system, the second cooling system provided with second cooling means through which a cooling medium for cooling the engine body can be circulated, and the first bypass passage A first adjusting means provided to adjust a flow rate of the flowing cooling medium and a flow rate of the cooling medium flowing through the first cooling means; an intake cooling passage of the first cooling system connected to the exhaust cooling device; Communication with the second cooling system Providing a second regulating means provided to regulate, and a circulating device for circulating the cooling medium in the first cooling system and the second cooling system, cooling system, the.

  For example, the circulation device may be provided on the upstream side of both the first cooling unit and the first adjusting unit and on the downstream side of the intake air cooling device. The circulation device may be provided so that the cooling medium is supplied toward the engine body and the cooling medium that has passed through the second cooling means flows before reaching the engine body.

  The cooling system described above includes a second bypass passage provided in the second cooling system so as to bypass the second cooling means, a flow rate of the cooling medium flowing through the second bypass passage, and the second cooling means. It is preferable to further include third adjusting means provided to adjust the flow rate of the cooling medium. In this case, the circulation device supplies the cooling medium toward the engine main body, and further allows the cooling medium that has passed through the second cooling means to flow before reaching the engine main body. It can be provided downstream.

  In the case of including a first control unit that controls the first adjustment unit, the first control unit may control the first adjustment unit based on the temperature of the cooling medium. Further, in the case of further including a second control unit that controls the second adjusting unit, the second control unit may control the second adjusting unit based on the temperature of the exhaust gas that has passed through the exhaust cooling device. .

  According to the above technology of the present disclosure, since the above configuration is provided, in the cooling system, the cooling medium can be more suitably distributed in the first cooling system and the second cooling system. It is possible to suitably cool the exhaust gas recirculated from the exhaust system to the intake system.

1 is a schematic configuration diagram of an internal combustion engine system for a vehicle to which a cooling system according to a first embodiment is applied. It is a control block diagram in the internal combustion engine system of FIG. It is a control flowchart based on 1st Embodiment. It is a schematic block diagram of the internal combustion engine system of the vehicle to which the cooling system which concerns on 2nd Embodiment was applied.

  Hereinafter, the present embodiment will be described with reference to the drawings. First, the first embodiment will be described.

  FIG. 1 shows a schematic diagram of an internal combustion engine system for a vehicle to which the cooling system CS of the first embodiment is applied. An internal combustion engine (hereinafter referred to as an engine) 10 according to the first embodiment is a type of engine that spontaneously ignites by directly injecting light oil, which is a fuel, into a combustion chamber in a compressed state from an injector, that is, a diesel engine. However, this does not limit the engine to which the technology of the present disclosure is applied, and the technology of the present disclosure can be applied to various other types of engines.

  The engine 10 is a so-called multi-cylinder engine in which a plurality of cylinders are formed in the engine body 12, but may be a single-cylinder engine. In the intake system of the engine 10, air (here, fresh air) drawn into the intake passage 14 through an air cleaner (not shown) is supplied to the compressor 18 of the first turbocharger 16, the first intercooler (first intake cooling device) 20, 2 The compressor 24 of the turbocharger 22, the second intercooler (second intake air cooling device) 26, the intake manifold, the intake port, and the intake valve are sequentially sucked into the combustion chamber of each cylinder formed in the engine body 12. Is done. The fuel injected from the injector 13 (not shown in FIG. 1) is combusted in the combustion chamber, and exhaust gas generated by the combustion is discharged from the combustion chamber to the exhaust passage 30 via an exhaust valve (not shown). In the exhaust system of the engine 10, exhaust gas is discharged through an exhaust valve, an exhaust port, an exhaust manifold, a turbine 32 of the second turbocharger 22, a turbine 34 of the first turbocharger 16, and an exhaust purification device 36 in order. Is done. Thus, the engine 10 includes two turbochargers. Therefore, the vehicle equipped with the engine 10 is a two-stage turbo equipped vehicle.

  The engine 10 is provided with an exhaust gas recirculation system (EGR system) 40 that guides part of the exhaust gas flowing through the exhaust passage 30 (exhaust system) to the intake passage 14 (intake system). The EGR system 40 includes a passage (EGR passage) 42 connecting the exhaust passage 30 and the intake passage 14, an EGR valve 44 for adjusting the communication state of the EGR passage 42, and exhaust gas (EGR) recirculated from the exhaust system to the intake system. Gas) cooling EGR cooler (exhaust air cooling device of the intake air cooling device) 46. Further, the EGR system 40 includes an EGR bypass passage 47 that bypasses the EGR cooler 46. The EGR bypass passage 47 branches on the upstream side of the EGR cooler 46 and is connected to the EGR valve 44 on the downstream side of the EGR cooler 46. The EGR valve 44 is configured as an electromagnetic valve whose operation is controlled by an electronic control unit (hereinafter referred to as ECU) 90, which will be described later, particularly as a three-way valve here. The EGR valve 44 can be controlled to various opening degrees, and when EGR gas is unnecessary, that is, when the EGR is off, the EGR valve 44 is completely closed, that is, closed so that the recirculation of the EGR gas does not occur. The EGR valve 44 is disposed on the downstream side of the EGR cooler 46, that is, on the intake system side, but is not limited thereto. Here, one end on the upstream side of the EGR passage 42 is connected to the exhaust manifold, and the other end on the downstream side thereof is connected to the intake manifold. However, these connection points are not limited to these positions. The EGR cooler 46 is composed of two EGR coolers 52 and 62 as will be described later, both of which generate heat exchange between the cooling water that is the cooling medium and the exhaust gas (EGR gas), and the EGR gas. Is a heat exchanger configured to cool the air.

  Now, the cooling system CS applied to the engine 10 will be described.

  As shown in FIG. 1, the cooling system CS is configured to include a first cooling system C1 and a second cooling system C2. In the cooling system CS, cooling water having the same component as so-called engine cooling water circulates as a cooling medium over both the first cooling system C1 and the second cooling system C2. However, this does not limit the type of cooling medium. First, the first cooling system C1 will be described. In FIG. 1, the first cooling system C1 and the second cooling system C2 are indicated by broken lines. In FIG. 1, a branch point or a merge point of the flow path or the passage in the systems C <b> 1 and C <b> 2 of the cooling system CS is represented by a black circle.

  The first cooling system C1 is configured integrally with the second cooling system C2, and is configured to communicate with the second cooling system. However, the first cooling system C1 is designed as a system having a cooling configuration of the intake system of the engine 10. Yes. In the present disclosure, unless otherwise specified, the term “intake” includes not only the air that is sucked into the intake passage 14 through the air cleaner, that is, fresh air, but also the intake passage 14 (or the combustion chamber) through the EGR passage 42. EGR gas introduced into the above is also included. The first cooling system C1 is provided with a first EGR cooler (first exhaust cooling unit) 52 included in the EGR cooler 46, and a first heat exchanger (first cooling means) 54. Further, the first cooling system C <b> 1 is provided with a first intercooler 20 and a second intercooler 26. The first cooling system C1 cools the cooling water of the intercoolers (intake air cooling devices) 20 and 26 so as to cool the air sucked into the intake passage 14, particularly the air compressed by the compressors 18 and 24 of the turbocharger here. It includes a flow path and also includes a cooling water flow path for the first EGR cooler 52. The intercoolers 20 and 26 are heat exchangers configured to cause heat exchange between the cooling water and the intake air. The first heat exchanger 54 is a so-called radiator, and is configured to cool the cooling water by causing heat exchange between the cooling water and the outside air.

  Further, in the first cooling system C1, a first bypass passage 55 that bypasses the first heat exchanger 54 is provided. The first bypass passage 55 is configured to branch from the flow path on the upstream side of the first heat exchanger 54 and merge with the flow path on the downstream side of the first heat exchanger 54. A first valve (first adjusting means) 56 is provided in the first bypass passage 55. The first valve 56 is configured as an electromagnetic valve whose operation is controlled by an ECU 90, which will be described later, particularly as a three-way valve here. The first valve 56 can be controlled to various opening degrees. One of the two inlet portions of the valve 56 is connected to the first heat exchanger 54, and the other inlet portion 56 b of the two inlet portions is an upstream branch portion of the bypass passage 55. Connected to B1. The branch part B1 will be described later. Further, the outlet portion 56c of the first valve 56 is connected to the branch portion B2. The branching section B <b> 2 connects the flow path from the first heat exchanger 54 to the cooling water flow path inlet of the first intercooler 20, the cooling water flow path inlet of the second intercooler 26, and the first EGR cooler 52. It is comprised so that it may branch into three flow paths toward each with the inlet_port | entrance part of a cooling water flow path. And the three flow paths from each of the exit part of the cooling water flow path of the 1st intercooler 20, the exit part of the cooling water flow path of the 2nd intercooler 26, and the exit part of the cooling water flow path of the 1st EGR cooler 52 A merging portion B3 where the merging is provided. This junction B3 is connected to a flow path connected to the pump 70 described later, and is connected to the inlet of the first heat exchanger 54 via the pump 70.

  The second cooling system C2 is configured integrally with the first cooling system C1, and is configured to communicate with the first cooling system, but is designed as a system having a cooling configuration of the engine body 12 of the engine 10. ing. Therefore, the second cooling system C <b> 2 includes a cooling water passage formed in the engine body 12, that is, a cooling water passage of the engine body 12. A second heat exchanger (second cooling means) 64 is provided in the second cooling system C2. The second cooling system C <b> 2 is provided with a second EGR cooler (second exhaust cooling unit) 62 included in the EGR cooler 46. However, the second EGR cooler 62 is provided on the upstream side of the first EGR cooler 52. As described above, the cooling system CS is cooled by the second EGR cooler 62 (having a cooling path) incorporated in the second cooling system C2, and then incorporated in the first cooling system C1 (having the cooling path). ) A two-stage cooling method with cooling by the first EGR cooler 52 is adopted as the cooling configuration of the EGR gas. The second heat exchanger 64 is a so-called radiator, and is configured to cool the cooling water by causing heat exchange between the cooling water and the outside air. As described above, the second cooling system C2 includes the flow path of the cooling water for the second EGR cooler, but is configured to allow the cooling water for cooling the engine body 12 to flow. Therefore, generally, the cooling water flowing through the second cooling system C2 has a higher temperature than the cooling water flowing through the first cooling system C1, so the first cooling system C1 is referred to as a low-temperature cooling system, and the second cooling system C2 is referred to as “cooling water”. It may be referred to as a high temperature cooling system. At this time, the first heat exchanger 54 of the first cooling system C1 is referred to as a low temperature heat exchanger (LT Radiator), and the second heat exchanger 64 of the second cooling system C2 is referred to as a high temperature heat exchanger (HT Radiator). May be.

  Further, in the second cooling system C2, a second bypass passage 66 that bypasses the second heat exchanger 64 is provided. A valve provided in the second bypass passage 66 so as to adjust the flow rate of the cooling water flowing through the second bypass passage 66 and the flow rate of the cooling water flowing through the second heat exchanger 64 (third adjusting means). 68 is provided. Here, the valve 68 is configured as a thermostat valve, and is configured to automatically operate according to the temperature of the cooling water flowing therethrough. However, the valve 68 may be configured as an electromagnetic valve whose operation is controlled by an ECU 90 described later. The valve 68 is in particular configured here as a three-way valve. The inlet 68 a of the valve 68 is connected to the outlet of the cooling water passage of the engine body 12. One outlet portion 68b of the two outlet portions of the valve 68 is connected to the second heat exchanger 64, and the other outlet portion 68c of the two outlet portions is connected to the inlet portion of the pump 70 described later. ing. That is, the second bypass passage 66 is configured to be branched by the valve 68 on the upstream side of the second heat exchanger 64 and to be merged by the pump 70 on the downstream side of the second heat exchanger 64. The pump 70 is provided on the downstream side of the second heat exchanger 64 and is configured such that the cooling water that has passed through the second heat exchanger 64 is sucked in. The outlet portion of the pump 70 is connected to the cooling water flow path of the engine body 12 and to the branch portion B4. The branch part B4 is configured to branch into three flow paths directed to each of the inlet part of the cooling water flow path of the second EGR cooler 62, the branch part B1, and the second valve (second adjusting means) 72. Has been. The outlet of the cooling water flow path of the second EGR cooler 62 is connected to the inlet of the pump 70.

  The branch part B1 is directed to each of the first heat exchanger 54 and the first bypass passage 55 for the coolant that has reached the branch part B1 via the branch part B4 among the coolant discharged from the pump 70. It is comprised so that it may divide into two flow paths.

  The second valve 72 connects the outlet portion 56 c of the first valve 56 (connected to the first heat exchanger 54 and the first bypass passage 55 on the upstream side) to the inlet portion of the cooling water flow path of the first EGR cooler 52. Provided in the intake air cooling passage 57 connected to the flow passage, that is, downstream of the first heat exchanger 54 and the first bypass passage 55 in the first cooling system C1 and connected to the cooling water passage of the first EGR cooler 52 of the EGR cooler 46. It has been. The second valve 72 is configured as an electromagnetic valve whose operation is controlled by an ECU 90, which will be described later, particularly as a three-way valve here. The second valve 72 has two inlet portions 72a and 72b. One inlet 72 a is connected to a branch B 2 on the downstream side of the outlet 56 c of the first valve 56, and the other inlet 72 b is connected to a branch B 4 on the downstream side of the pump 70. The outlet 72 c of the second valve 72 is connected to the inlet of the cooling water flow path of the first EGR cooler 52. In addition, the 2nd valve | bulb 72 can be controlled by various opening degree, for example, can also make the flow path from the 1st cooling system C1 and the flow path from the 2nd cooling system C2 both obstruct | occluded. Further, for example, the second valve 72 can be in a state in which both the flow path of the first cooling system C1 and the flow path from the second cooling system C2 are substantially closed, and either one can be flowed in a very small amount.

  In FIG. 1, the flow path of the cooling water from the branching section B3 to the pump 70 includes the cooling water flow path from the outlet of the cooling water flow path of the second EGR cooler 62 to the pump 70 and the upstream side of the pump 70. It merges at the junction B5.

  In addition, the 1st throttle valve 58a is provided between the exit part of the cooling water flow path of the 1st intercooler 20, and the confluence | merging part B3, Between the exit part of the cooling water flow path of the 2nd intercooler 26 and the confluence | merging part B3 The second throttle valve 58b is provided, and the third throttle valve 58c is provided between the outlet of the cooling water flow path of the second EGR cooler 62 and the junction B5 upstream of the inlet of the pump 70. The first to third throttle valves 58a, 58b, and 58c are simply configured as valves for adjusting the flow rate, and specifically, are configured as orifices here. However, each of the first to third throttle valves 58a, 58b, and 58c may have other configurations, for example, may be configured as an electromagnetic valve controlled by an ECU 90 described later. In addition, each of these throttle valves 58a, 58b, 58c may be provided at other locations, may be simply omitted by adjusting the piping configuration, or uses one or more other valves. May be omitted.

  The pump 70 is provided as both the pump of the first cooling system C1 and the pump of the second cooling system C2, that is, as a circulation device of the cooling system CS. And the pump 70 which is a water pump is comprised as an electric pump here.

  In the cooling system CS, as described above, the first cooling system C1 and the second cooling system C2 are integrally configured. In the first cooling system C1, the cooling water discharged from the pump 70 passes through the branch portions B4 and B1, and according to the state of the first valve 56, the first heat exchanger 54, the first bypass passage 55, It flows through either one or both. And the cooling water which passed through any one or both of the 1st heat exchanger 54 and the 1st bypass channel 55 is the 1st intercooler 20, the 2nd intercooler 26, and (via the 1st valve 72). It is used for cooling in the first EGR cooler 52 and reaches the junction B3. And the cooling water which passed through the junction B3 is sucked into the pump 70 through the junction B5. That is, in the first cooling system C1, the cooling water discharged from the pump 70 passes through one or both of the first heat exchanger 54 and the first bypass passage 55, and then the intake air cooling device, that is, the first cooling system. It can flow through the intercooler 20, the second intercooler 26, and the first EGR cooler 52 and return to the pump 70. Thus, in the first cooling system C1, the pump 70 is provided on the upstream side of both the first heat exchanger 54 and the first valve 56 and on the downstream side of the intake air cooling device.

  In the second cooling system C2, the cooling water discharged from the pump 70 flows to the second EGR cooler 62 via the engine body 12 and the branching section B4, and the second valve 72 according to the state of the second valve 72. It can merge with the cooling water to the 1st EGR cooler 52 via. Then, the cooling water that has passed through the engine body 12 flows toward one or both of the second heat exchanger 64 and the pump 70 according to the state of the valve 68. Then, the cooling water that has passed through the second heat exchanger 64 is sucked into the pump 70. That is, in the second cooling system C2, the cooling water discharged from the pump 70 and used for cooling in the engine body 12 passes through one or both of the second heat exchanger 64 and the pump 70. Return to pump 70. On the other hand, the cooling water that has passed through the second EGR cooler 62 is sucked into the pump 70 via the third throttle valve 58c and the junction B5. As described above, in the second cooling system C2, the pump 70 supplies the cooling medium toward the engine body 12, and the cooling water that has passed through the second heat exchanger 64 flows before reaching the engine body 12. Furthermore, it is provided downstream of the second bypass passage.

  The ECU 90 for controlling the operation of the first valve 56 and the second valve 72 and for controlling the operation of the injector 13, the EGR valve 44 and the like is for obtaining (detecting or estimating) various values. Various sensors that electrically output signals are connected. Here, some of them will be specifically described with reference to FIGS. An air flow meter 92 for detecting the amount of intake air is provided in the intake passage 14. The intake passage 14 is provided with an intake air temperature sensor 94 for detecting the intake air temperature and a pressure sensor 96 for detecting the supercharging pressure. Further, a temperature sensor (hereinafter referred to as an EGR temperature sensor) 98 for detecting the temperature of the exhaust gas, that is, the EGR gas (EGR temperature) that has passed through the EGR cooler 46, particularly the first EGR cooler 52 on the downstream side (of the second EGR cooler 62). Is provided in the EGR passage portion downstream of the EGR cooler 46. Further, an accelerator opening sensor 100 is provided for detecting a position corresponding to the depression amount of the accelerator pedal operated by the driver, that is, an accelerator opening. A crank position sensor 102 for detecting a crank rotation signal of a crankshaft connected to the piston via a connecting rod is attached to the cylinder block in which the piston reciprocates in each cylinder. Here, the crank position sensor 102 is also used as an engine speed sensor for detecting the engine speed. Further, a cooling water temperature sensor 104 for detecting the cooling water temperature of the engine 10 is provided. Further, a vehicle speed sensor 106 for detecting the vehicle speed is also provided. An outside air temperature sensor 108 for detecting the outside air temperature is also provided.

  The ECU 90 includes a calculation device (for example, a CPU (Central Processing Unit)), a storage device (for example, a ROM (Read Only Memory), a RAM (Random Access Memory)), an A / D converter, an input interface, an output interface, and the like. It is configured as a computer. The aforementioned various sensors are electrically connected to the input interface. Based on the output from these various sensors, the ECU 90 electrically outputs various operation signals (drive signals) from the output interface so that the engine 10 can be smoothly operated or operated according to a preset program or the like. . Thus, the operation of the injector 13, the opening degree of the EGR valve 44, the opening degree of the first valve 56, the opening degree of the second valve 72, and the like are controlled. In addition, the operation of the pump 70 that is an electric pump (for example, the number of revolutions of the pump) is also controlled by the ECU 90 here. Therefore, the ECU 90 functions as a control unit for each of the injector 13, the EGR valve 44, the first valve 56, the second valve 72, and the pump 70. Therefore, for example, the ECU 90 includes a functional unit corresponding to a first control unit that controls the first valve 56 and a functional unit corresponding to a second control unit that controls the second valve 72. The pump 70 is not limited to an electric pump whose operation is controlled by the ECU 90, and may be another type of pump or a pump driven by the power of the engine 10. Good.

  Here, the ECU 90 opens the EGR valve 44 based on the engine operating state determined based on the engine load (for example, intake air amount) and engine rotational speed detected (acquired) based on the outputs of the various sensors. To control. The engine load is not limited to being determined only by the intake air amount, and may be determined using, for example, one of the intake air amount, the accelerator opening, and the intake pressure, or any combination thereof. Various data constructed according to the performance, characteristics, etc. of the engine 10 can be used for EGR valve control.

  Next, control of the first valve 56 and the second valve 72 will be described based on the flowchart of FIG. Note that the routine of FIG. 3 is repeated at predetermined time intervals.

  First, in step S301, the ECU 90 determines that the engine operating state determined as described above is a predetermined operating state, specifically, an operating state in which the EGR valve 44 is opened and EGR gas is recirculated from the exhaust system to the intake system. It is determined whether or not the operating state requires gas. That is, when the EGR valve 44 is operated so that the EGR gas is recirculated to the intake system, an affirmative determination is made in the determination in step S301. On the other hand, when the EGR valve 44 is in an operating state in which the EGR gas is not recirculated to the intake system (when the EGR cooler 46 side and the EGR bypass passage 46 side are also closed), a negative determination is made in step S301. The process proceeds to step S303.

  In step S303, the ECU 90 determines whether or not the engine 10 is in a warm-up state. Whether or not the engine is in a warm-up state is determined based on the output of the coolant temperature sensor 104. The cooling water temperature sensor 104 is provided so as to detect the temperature of the cooling water at the outlet of the cooling water flow path of the engine body 12 (see FIG. 1). When the engine coolant temperature is lower than the predetermined temperature, it is determined here that the engine is warming up. Generally, when the engine 10 is started, the engine cooling water temperature (cooling medium temperature) acquired by the ECU 90 is lower than a predetermined temperature. In this case, the ECU 90 makes an affirmative determination in step S303. When the acquired engine coolant temperature is equal to or higher than the predetermined temperature, a negative determination is made in step S303, assuming that the engine is not warmed up, specifically, that the engine is warmed up. However, in the present embodiment, it is determined whether or not the engine is in a warm-up state based on the output of the cooling water temperature sensor 104. However, in the technology of the present disclosure, whether or not the engine is in a warm-up state is determined by a method other than the coolant temperature sensor 104. It may be performed using a sensor. For example, the determination as to whether or not the engine is in a warm-up state may be made based on the temperature of another part such as the temperature of a metal part such as a cylinder block or a cylinder head.

  Since the engine coolant temperature acquired in the determination in step S303 is lower than the predetermined temperature, if an affirmative determination is made as a warm-up state, the ECU 90 proceeds to step S305. By reaching step S305, the ECU 90 controls the first valve 56 to the bypass side opening so that the cooling water flows mainly to the first bypass passage 55 side instead of passing the first heat exchanger 54, and The operation signal is controlled so as to control the second valve 72 to the closed side opening degree so as to suppress direct merging or inflow of the cooling water discharged from the pump 70 to the cooling water flowing toward the first EGR cooler 52. Output.

  When step S305 is reached, since the engine 10 is in a warm-up state (affirmative determination in step S303), first cooling water is mainly flowed not to the first heat exchanger 54 side but to the first bypass passage 55 side. By controlling the valve 56, cooling of the cooling water can be suppressed and warming up of the engine 10 can be promoted suitably. By reaching step S305 as such an opening, a bypass opening as a predetermined opening is set. As the bypass side opening, bypass side opening data is determined and stored in advance based on experiments or the like. And based on the engine operating state at that time, in this embodiment, it is obtained based on the engine output, more specifically, based on the output of the accelerator opening sensor 100 corresponding to the driver's output request here. By referring to the bypass side opening degree data by the value, the opening degree of the first valve 56 corresponding to the current operation state is determined, and the operation of the first valve 56 is controlled so as to be the opening degree. . However, the opening on the bypass side includes an opening that prevents the cooling water from flowing through the first heat exchanger 54 at all. In the initial state, the opening on the bypass side is set as the opening of the first valve, but a cooling side opening described later may be set.

  On the other hand, when reaching step S305, as the opening of the second valve 72, direct merging or inflow of the cooling water discharged from the pump 70 to the cooling water flowing toward the first EGR cooler 52 is suppressed. The closing side opening is set. This is because when reaching step S305, the operating state is negatively determined in step S301, and is not the operating state in which the EGR gas is recirculated to the intake system. Here, since the EGR gas is not in an operating state in which it is recirculated to the intake system, that is, the EGR valve 44 is controlled to be in a closed state, the second valve 72 is in a completely closed state. Since the total flow rate of the pump 70 decreases due to the complete blockage of the second valve 72, for example, the efficiency of the pump 70 and the drive loss can be reduced. As described above, in the present embodiment, when the flow reaches step S305, the flow of the cooling water to the first EGR cooler 52 is suppressed by the complete closing of the second valve 72. However, the technique of the present disclosure is the first EGR at this time. It does not exclude that the flow of the cooling water to the cooler 52 is generated. For example, the opening degree of the second valve 72 may be controlled based on the output of the EGR temperature sensor 98 to cause a flow of cooling water to the first EGR cooler 52. In the warm-up state, since the valve 68 is mainly closed to the second heat exchanger 26 side, the cooling water flowing out from the cooling water flow path of the engine body 12 is pumped through the second bypass passage 66. Can be reached. Here, in the initial state, the closing side opening degree is set as the opening degree of the second valve 72, but an opening side opening degree described later may be set. The routine ends after step S305.

  If the engine coolant temperature acquired in the determination in step S303 is equal to or higher than the predetermined temperature, a negative determination is made that the engine cooling water temperature is not warmed up, and the ECU 90 proceeds to step S307. By reaching step S307, the ECU 90 controls the first valve 56 to the cooling side opening so that the cooling water flows mainly to the first heat exchanger 54 side instead of passing through the first bypass passage 55, and The operation signal is used to control the second valve 72 to the closed side opening degree so as to suppress direct merging or inflow of the cooling water discharged from the pump 70 to the cooling water flowing toward the first EGR cooler 52. Is output. When step S307 is reached, since the engine 10 is not warmed up, the cooling side opening degree as the predetermined opening degree is set so that the cooling water flows not to the first bypass passage 55 side but to the first heat exchanger 54 side. Is done. As the cooling side opening degree, cooling side opening degree data is determined and stored in advance based on experiments or the like. And based on the engine operating state at that time, in this embodiment, it is obtained based on the engine output, more specifically, based on the output of the accelerator opening sensor 100 corresponding to the driver's output request here. By referring to the cooling side opening degree data by the value, the opening degree of the first valve 56 corresponding to the current operation state is determined, and the operation of the first valve 56 is controlled so as to be the opening degree. . However, the cooling side opening includes an opening that prevents the cooling water from flowing through the first bypass passage 55 at all. It should be noted that, as described above in step S305, the closing side opening degree is set as the opening degree of the second valve 72 when reaching step S307. Note that the routine ends after step S307.

  On the other hand, when the operation state is an operation state that requires EGR gas in step S301, an affirmative determination is made in step S309, as in step S303, the ECU 90 determines whether or not the engine 10 is in a warm-up state. judge. Since the determination in step S309 is the same as the determination in step S303, the description thereof is omitted here.

  Since the engine coolant temperature acquired in the determination in step S309 is lower than the predetermined temperature, if the determination is positive as a warm-up state, the ECU 90 proceeds to step S311. By reaching step S311, the ECU 90 controls the first valve 56 to the above bypass side opening so that the cooling water flows mainly to the first bypass passage 55 side instead of passing the first heat exchanger 54. The operation signal so as to control the second valve 72 to the open side opening so as to cause direct confluence or inflow of the cooling water discharged from the pump 70 to the cooling water flowing toward the first EGR cooler 52. Is output. The control at the bypass side opening of the first valve 56 is as already described in step S305. The second valve 72 is controlled to an open side opening degree that is a predetermined opening degree as described below so as to prevent or suppress the generation of condensed water due to the cooling of the EGR gas in the EGR cooler 46. Note that the routine ends after step S311.

  As the opening side opening in the control of the second valve 72, opening side opening data is determined and stored in advance based on experiments or the like. And based on the engine operating state at that time, in this embodiment, it is obtained based on the engine output, more specifically, based on the output of the accelerator opening sensor 100 corresponding to the driver's output request here. By referring to the open side opening degree data by value, the opening degree of the second valve 72 corresponding to the operation state at that time (the supply amount from the second cooling system C2 to the first cooling system C1 is maximized). And the operation of the second valve 72 is controlled so that the opening is reached (with the opening being the target opening).

  Further, when the opening degree of the second valve 72 is set as the opening degree of the second valve 72, the control of the second valve 72 is based on the temperature of the EGR gas, that is, the output of the EGR temperature sensor 98. Feedback control is executed. Specifically, it is determined whether or not the temperature of the EGR gas acquired based on the output of the EGR temperature sensor 98 is lower than a predetermined EGR temperature. The predetermined EGR temperature here is a temperature equal to or higher than a temperature at which condensed water is likely to be generated due to condensation of moisture in the EGR gas (hereinafter referred to as condensed water generation temperature), and is previously determined and stored based on experiments or the like. ing. The condensed water generation temperature can be defined as meaning that the possibility of condensed water generation is equal to or higher than a predetermined level when the temperature of the EGR gas is lower than the condensed water generation temperature. The predetermined EGR temperature may be a condensed water generation temperature, but here is a temperature higher by a predetermined margin (for example, 5 ° C.) than that. The predetermined EGR temperature is not limited to a predetermined value, and may be calculated and set in real time by a predetermined calculation based on outputs from various sensors. Based on the output of the EGR temperature sensor 98, the ECU 90 detects (acquires) the temperature of the EGR gas. When the acquired EGR gas temperature is lower than the predetermined EGR temperature, the ECU 90 calculates a correction value with reference to predetermined data and the like based on the acquired EGR gas temperature. Then, by applying the correction value to the opening on the opening side, that is, the opening based on the opening side opening data, the total flow rate of the cooling water directly sent from the pump 70 to the cooling water flowing into the first EGR cooler 52 is increased. Thus, the opening degree of the second valve 72 is corrected. Thereby, the cooling capacity of the EGR gas in the first EGR cooler 52 is suppressed, and it is possible to suppress unwanted cooling of the EGR gas.

  Note that when the process reaches step S311, it is in a warm-up state. At this time, when the temperature of the engine cooling water is low and there is a possibility that condensed water is generated even when the cooling water is supplied from the second cooling system C2, for example, when the temperature of the EGR gas is lower than the predetermined EGR temperature, The opening degree of the EGR valve 44 may be adjusted so that the EGR gas flows positively through the EGR bypass passage 47 instead of the EGR cooler 46 side.

  On the other hand, if the determination in step S309 is not a warm-up state and the determination is negative, the ECU 90 proceeds to step S313. By reaching step S313, the ECU 90 controls the first valve 56 to the cooling side opening degree so that the cooling water flows to the first heat exchanger 54 side instead of mainly passing through the first bypass passage 55. The second valve 72 is operated to control the open side opening degree so as to cause direct merging or inflow of the cooling water discharged from the pump 70 to the cooling water flowing toward the first EGR cooler 52. Output a signal. The control to the cooling side opening of the first valve 56 is as already described in step S307, and the control to the opening side of the second valve 72 is as already described in step S311. Note that the routine ends after step S313.

  As described above, according to the cooling system CS of the first embodiment, the cooling water is suitably circulated through the integrally configured first cooling system C1 and second cooling system C2 by the operation of the pump 70. be able to. As described above, the engine warm-up can be more suitably caused by controlling the first valve 56 based on the determination as to whether or not the warm-up state is based on the coolant temperature. Further, as described above, when the EGR gas needs to be recirculated, by controlling the second valve 72 while correcting based on the temperature of the EGR gas, the cooling of the EGR gas is preferably caused. The generation of condensed water can be suppressed.

  In the first cooling system C1, the cooling water discharged from the pump 70 passes through one or both of the first heat exchanger 54 and the first bypass passage 55, and then the intake air cooling device, that is, the first cooling system. The first intercooler 20, the second intercooler 26, and the first EGR cooler 52 can flow and return to the pump 70. That is, the cooling water discharged from the single pump 70 is sufficiently cooled by the first heat exchanger 54 as needed, and then supplied to the intake air cooling device. Therefore, in the first cooling system C1, the intake system of the engine 10 can be sufficiently cooled, and thus fuel consumption and the like can be improved.

  Further, in the second cooling system C2, the cooling water discharged from the pump 70 and used for cooling in the engine body 12 is either or both of the second heat exchanger 64 and the second bypass passage 66. To return to the pump 70. Thus, the cooling water discharged from the single pump 70 can be cooled after being used for cooling the engine body 12. Therefore, the temperature of the cooling water flowing through the engine body 12 can be maintained in a desired temperature range. Further, the temperature of the cooling water flowing into or sucked into the pump 70 in the second cooling system C2 can be made closer to the temperature of the cooling water flowing into or sucked into the pump 70 in the first cooling system C1.

  Moreover, in the said 1st Embodiment, the cooling water flow path of the 2nd EGR cooler 62 was also included in the 2nd cooling system C2. Therefore, according to the cooling system CS, the heat of the EGR gas can also be used for warming up the engine via the second EGR cooler.

  In the control of the first valve 56 and the control of the second valve 72, the output of the cooling water temperature sensor 104, that is, the cooling water temperature, the output of the vehicle speed sensor 106, that is, the vehicle speed, the output of the outside air temperature sensor 108, that is, the outside Correction control, for example, feedback control may be performed based on at least one of the air temperature and the number of rotations of a cooling fan (not shown). A first heat exchanger 54 and a second heat exchanger 64 are arranged in this order behind the front grille of the vehicle, and the cooling fan is arranged further behind the second heat exchanger 64 and in front of the engine body 12. Has been.

  In the first embodiment, the two EGR coolers 52 and 62 are arranged in series in contact with each other. However, the two EGR coolers 52 and 62 may be completely separated, or conversely, may be configured as a completely integrated EGR cooler 46. Good.

  Moreover, in the said embodiment, the 1st valve | bulb 56 was controlled based on determination whether it is a warming-up state based on a cooling water temperature. However, as described above, the determination as to whether or not the engine is in the warm-up state may be performed using various sensors, and may be performed based on the temperature of various portions as well as the cooling water. The first valve 56 can be controlled based on the determination of whether or not it is in a warm-up state by various methods or means.

  Next, a second embodiment will be described based on FIG. The second embodiment is different from the first embodiment particularly in terms of the configuration of the EGR cooler and the first and second adjusting means. Therefore, the difference will be mainly described below, and in the following description and in FIG. 4, the same reference numerals are given to the components corresponding to the components already described, and the overlapping description will be omitted.

  In the cooling system CS ′ of the second embodiment, the EGR cooler 46 does not employ a multistage cooling system. In the second embodiment, the EGR cooler 46 includes only a configuration corresponding to the first EGR cooler 52. That is, the cooling of the EGR gas in the EGR cooler 46 is performed with the cooling water that has passed through the second valve, and is not performed with the cooling water that is directly sent from the pump 70. Accordingly, in the cooling system CS ′ of the second embodiment, the flow path configuration related to the second EGR cooler 62 of the EGR cooler 46 of the first embodiment is omitted.

  Thus, in 2nd Embodiment, cost reduction can be aimed at further by making EGR cooler 46 into a simple structure compared with the said 1st Embodiment. In particular, such a configuration is suitable for a compact engine. However, as described in the first embodiment, the EGR gas can be suitably cooled in the EGR cooler 46 by controlling the second valve 72.

  Furthermore, in the cooling system CS ′ of the second embodiment, two valves 56p and 56q are provided as the first adjusting means. These valves 56p and 56q are each configured as a two-way valve and are controlled by the ECU 90. The valve 56 p is a flow path on the downstream side of the first heat exchanger 54 and is provided on the upstream side of the junction B 6 of the first bypass passage 55, and the valve 56 q is provided on the bypass passage 55. As described in the control of the first valve 56 in the first embodiment, the valves 56p and 56q are the flow rate of the cooling water flowing through the first bypass passage 55 and the flow rate of the cooling water flowing through the first heat exchanger 54. Controlled to adjust.

  In the cooling system CS ′ of the second embodiment, one valve 72p is provided as the second adjusting means. The valve 72p is configured as a two-way valve and is controlled by the ECU 90. The valve 72p takes in the intake air from the branch part B4 so as to adjust the communication between the intake air cooling passage 57 of the first cooling system C1 through which the cooling water flows to the EGR cooler 46, which is an exhaust cooling device, and the second cooling system C2. It is provided in a flow path or passage extending to the cooling passage 57. The valve 72p adjusts the communication between the intake cooling passage 57 of the first cooling system C1 connected to the EGR cooler 46 and the second cooling system C2, as described in the control of the second valve 72 in the first embodiment. To be controlled. In addition to the valve 72p, another valve (not shown) may be provided in the intake air cooling passage 57 as the second adjusting means, and this valve can be configured as a two-way valve controlled by the ECU 90. .

  Although the second embodiment has been described above, the technology of the present disclosure does not limit the number and configuration of valves as the first adjustment means and the number and configuration of valves as the second adjustment means.

  In the first and second embodiments, the cooling systems CS and CS ′ according to the present disclosure are applied to an engine including two turbochargers. However, the technology of the present disclosure is not limited to an engine including only one turbocharger. It can also be applied to an engine without a turbocharger. Furthermore, the technology of the present disclosure can be applied to an engine that does not include an intercooler.

  The exemplary embodiments of the present disclosure have been described above, but the present disclosure can be variously modified. Various substitutions and modifications may be made without departing from the spirit and scope of the present disclosure as defined by the claims.

10 Engine 12 Engine body 40 EGR system 46 EGR cooler (exhaust cooling device)
52 1st EGR cooler (1st exhaust cooling part)
54 1st heat exchanger (1st cooling means)
55 First bypass passage 56 First valve (first adjusting means)
62 2nd EGR cooler (2nd exhaust cooling part)
64 Second heat exchanger (second cooling means)
66 Second bypass passage 70 Pump 72 Second valve (second adjusting means)
90 Electronic control unit (ECU)
CS, CS ′ cooling system C1 first cooling system C2 second cooling system

Claims (7)

A first cooling system is provided with a first cooling means for cooling the cooling medium, a first bypass passage that bypasses the first cooling means, and an intake air cooling device. A first cooling system including an exhaust cooling device configured to cool exhaust gas recirculated from an engine exhaust system to an intake system;
A second cooling system configured integrally with the first cooling system, the second cooling system provided with second cooling means through which a cooling medium for cooling the engine body can be circulated;
First adjusting means provided to adjust the flow rate of the cooling medium flowing through the first bypass passage and the flow rate of the cooling medium flowing through the first cooling means;
A second adjusting means provided to adjust communication between the intake cooling passage of the first cooling system connected to the exhaust cooling device and the second cooling system;
A cooling system comprising: a circulation device for circulating a cooling medium in the first cooling system and the second cooling system.   The cooling system according to claim 1, wherein the circulation device is provided on the upstream side of both the first cooling unit and the first adjusting unit and on the downstream side of the intake air cooling device.   The circulation device is provided so that a cooling medium is supplied toward the engine main body, and the cooling medium that has passed through the second cooling means flows before reaching the engine main body. As described in the cooling system. A second bypass passage provided to bypass the second cooling means in the second cooling system;
4. The apparatus according to claim 1, further comprising third adjusting means provided to adjust a flow rate of the cooling medium flowing through the second bypass passage and a flow rate of the cooling medium flowing through the second cooling means. The cooling system according to item.   The circulation device supplies a cooling medium toward the engine main body, and further downstream of the second bypass passage so that the cooling medium having passed through the second cooling means flows before reaching the engine main body. The cooling system according to claim 4 provided. A first control unit for controlling the first adjusting means;
The cooling system according to any one of claims 1 to 5, wherein the first control unit controls the first adjusting unit based on a temperature of a cooling medium. A second control unit for controlling the second adjusting means;
The second control unit controls the second adjusting unit based on the temperature of the exhaust gas that has passed through the exhaust cooling device.
The cooling system according to any one of claims 1 to 6.

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