JP5993759B2 - Engine intake cooling system - Google Patents

Description

  The present invention relates to an intake air cooling device provided in an engine with a supercharger.

  An engine with a supercharger that supercharges intake air by exhausting the engine is generally used. When the intake air is supercharged by the supercharger, the intake air temperature becomes high. In addition, when an EGR system that recirculates exhaust gas to the intake side is provided, the intake air temperature may further increase. If the intake air temperature becomes high, the fuel efficiency may decrease.

  In order to prevent this, a cooling device that lowers the temperature of the supercharged intake air is provided. The cooling device circulates, for example, engine cooling water in the intake passage, and reduces the intake air temperature with the cooling water.

  On the other hand, since the engine coolant is controlled to an optimum temperature for engine operation, the air-water temperature difference between the intake air and the coolant cannot be increased, and there is a limit to the decrease in the intake air temperature.

  On the other hand, the second cooling water circuit that branches off a part of the cooling water circuit of the engine is provided with a second radiator, and the temperature of the intake air sucked into the engine is lowered by the cooling water that has become low temperature by this radiator. A cooling device for an internal combustion engine is known (see Patent Document 1).

US Patent Application Publication No. 2008/0066697

  When the cooling water temperature is lowered to lower the intake air temperature, this low-temperature cooling water flows into the engine. In particular, when a low-temperature coolant temperature flows in when the engine is warmed up, the coolant temperature falls inside the engine, and the engine warm-up is delayed. If the engine warm-up is delayed, there is a problem that the fuel efficiency of the engine decreases.

  The present invention has been made in view of such problems, and provides an intake air cooling device for an engine that can improve a delay in warming up the engine while including a cooling device that cools intake air of the engine. For the purpose.

According to an aspect of the present invention, in an engine comprising a cooling water circuit through which engine cooling water circulates and a supercharger that supercharges engine intake air, The cooling water circuit includes a first cooling water circuit and a second cooling water circuit, and is cooled by the first intake air cooling device that cools the intake air with the cooling water of the first cooling water circuit, and the first intake air cooling device . A second intake air cooling device that further cools the intake air with the cooling water of the second cooling water circuit, and the first cooling water circuit recirculates the cooling water from the engine through the first intake cooling device. The second cooling water circuit returns the cooling water from the engine to the engine through the second intake air cooling device, and returns to the first cooling air device from the engine to the first intake air cooling device. 2 Get out of the intake air cooling system Characterized by comprising a cooling water towards the engine, the heat exchanger for exchanging heat between the.

  According to the above aspect, the cooling water in the first cooling water circuit coming out of the engine and the cooling water in the second cooling water circuit coming out of the second intake air cooling device exchange heat in the heat exchanger. The cooling water temperature of the second cooling water circuit that goes back to rises, and the engine warm-up delay is improved even when the engine is cold started.

It is explanatory drawing of the cooling device centering on the engine of the 1st Embodiment of this invention. It is explanatory drawing of the cooling device centering on the engine of the 2nd Embodiment of this invention. It is a flowchart of the process which the controller of the 2nd Embodiment of this invention performs. It is explanatory drawing of the cooling device centering on the engine of the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory diagram of a cooling device 1 centering on an engine 10 according to a first embodiment of the present invention.

  The cooling device 1 according to the first embodiment is mounted on a vehicle, for example, and includes an engine 10 that is a drive source of the vehicle and a supercharger (turbine) 18, and the temperature of the supercharged intake air is reduced to cooling water. (Coolant) is used for proper cooling.

  In FIG. 1, the thick arrow indicates the high temperature side cooling water circuit 31, the thin arrow indicates the low temperature side cooling water circuit 32, the dotted line indicates the flow of exhaust gas in the exhaust pipe 16, and the alternate long and short dash line indicates the flow of intake air in the intake pipe 14.

  The cooling device 1 includes an engine 10 and a cooling water circuit 30 that distributes the cooling water of the engine 10.

  A cooling water flow path 11 through which cooling water flows is formed inside the engine 10. The cooling water channel 11 communicates with the cooling water circuit 30. The cooling water passage 11 is provided with a water pump (W / P) 12 and a thermostat (T / S) 13.

  The water pump 12 circulates the cooling water through the cooling water passage 11 and the cooling water circuit 30. The thermostat 13 bypasses the radiator 41 when the temperature of the cooling water is low, and lowers the cooling water temperature through the radiator 41 when the temperature of the cooling water is high.

  An intake pipe 14 and an exhaust pipe 16 communicate with the engine 10. The intake pipe 14 is supercharged by the turbine 18. The temperature of the supercharged intake air is reduced by the high temperature side intercooler (first intake air cooling device) 71 and the low temperature side intercooler (second intake air cooling device) 72, and the intake air whose temperature has been reduced is sent to the engine 10. The exhaust pipe 16 discharges the exhaust of the engine 10 via the turbine 18. The exhaust gas rotates the turbine 18, and the intake air in the intake pipe 14 is supercharged by the rotation of the turbine 18.

  The engine 10 is provided with a fan 19. The fan 19 blows air to the radiator 41 and the sub-radiator 42, and cooling of these is promoted.

  An EGR circuit 20 branches from the exhaust pipe 16. The EGR circuit 20 constitutes an exhaust gas recirculation device (EGR) that recirculates a part of the exhaust gas to the intake air. The EGR circuit 20 includes a first EGR cooler (first exhaust cooling device) 21 on the high temperature side and a second EGR cooler (second exhaust cooling device) 22 located on the downstream side of the EGR circuit 20. And communicates with the intake pipe 14 via the EGR valve 23.

  By returning a part of the exhaust gas to the intake air by the EGR circuit 20, the oxygen concentration in the combustion chamber of the engine 10 can be lowered to lower the combustion temperature, and the generation of oxides such as NOx is suppressed. The lower the temperature of the exhaust gas that is recirculated, the higher the efficiency. Therefore, the first EGR cooler 21 on the high temperature side for lowering the exhaust temperature and the second EGR cooler 22 on the downstream side are also provided. ing.

  In the intake pipe 14, cooling water flows through the high-temperature side intercooler 71 and the low-temperature side intercooler 72, respectively, and reduces the temperature of the intake air supercharged by the turbine 18. Since the intake air temperature becomes high in some cases and the temperature difference with the cooling water is large, the intake air temperature is lowered in two stages of the high temperature side intercooler 71 and the low temperature side intercooler 72. The intake air whose temperature has been lowered by the high temperature side intercooler 71 is further lowered by the low temperature side intercooler 72. In the intake pipe 14, an EGR valve 23 is provided downstream of the high temperature side intercooler 71 and the low temperature side intercooler 72. The EGR valve 23 controls the amount of exhaust gas recirculated to the intake pipe 14 via the EGR circuit 20.

  The cooling water circuit 30 includes a high temperature side cooling water circuit (first cooling water circuit) 31 and a low temperature side cooling water circuit (second cooling water circuit) 32.

  The high temperature side cooling water circuit 31 includes a cooling water flow path 11 of the engine 10, a radiator (first radiator) 41, a high temperature side first EGR cooler 21, and a second high temperature side second EGR located downstream thereof. It is constituted by a cooling water circuit that passes through the cooler 22.

  In the high temperature side cooling water circuit 31, the cooling water sent from the water pump 12 of the engine 10 circulates through the cooling water flow path 11 of the engine and returns to the cooling water flow path of the engine 10 again via the radiator 41. . A part of the cooling water sent out from the water pump 12 exits the engine 10 and passes through the first EGR cooler 21 on the high temperature side and the second EGR cooler 22 on the downstream side of the high temperature side. Then, it returns to the cooling water flow path 11 of the engine 10 again. A part of the cooling water sent from the water pump 12 exits the engine 10 and returns to the cooling water flow path 11 of the engine 10 again via the heat exchanger 76 and the high temperature side intercooler 71.

  The low temperature side cooling water circuit 32 includes a thermostat 44, a sub-radiator (second radiator) 42, a low temperature side intercooler 72, and a cooling water circuit that passes through the heat exchanger 76.

  Cooling water delivered from the water pump of the engine 10 exits the engine 10 and is sent to the low temperature side intercooler 72 via the thermostat 44 and the sub-radiator 42. The cooling water exiting the low temperature side intercooler 72 returns to the cooling water flow path 11 of the engine 10 again through the heat exchanger 76. The thermostat 44 bypasses the sub radiator 42 when the temperature of the cooling water in the low temperature side cooling water circuit 32 is low, and prevents the cooling water temperature from further decreasing.

  As described above, the low temperature side cooling water circuit 32 is configured such that the cooling water passes through the sub radiator 42 so that the cooling water having a temperature lower than that of the high temperature side cooling water circuit 31 flows.

  The heat exchanger 76 performs heat exchange between the cooling water output from the engine 10 in the high temperature side cooling water circuit 31 and the cooling water output from the low temperature side intercooler 72 in the low temperature side cooling water circuit 32. The heat exchanger 76 has, for example, a double-pipe structure, and performs heat exchange by configuring the cooling water of the high temperature side cooling water circuit 31 and the cooling water of the low temperature side cooling water circuit 32 to face each other. Do.

  The operation of the thus configured first embodiment of the present invention will be described.

  When the engine 10 is started (cold start) from a state where the temperature of the engine 10 and the cooling water is low, such as when a long time has passed since the engine 10 was stopped, the sliding resistance of the engine 10 is large, and the catalyst Since the efficiency is also lowered, the operating efficiency of the engine 10 is low and the fuel efficiency is deteriorated, and the regulated substances in the exhaust also increase. For this reason, it is necessary to warm up the engine 10 as quickly as possible when the engine 10 is cold-started.

  Therefore, the cooling device 1 according to the first embodiment of the present invention operates as follows with the above-described configuration.

  In the engine 10, the cooling water circulates through the cooling water passage 11 by the water pump 12. At this time, when the cooling water temperature is low, the thermostat 13 is switched to bypass the radiator 41. Thereby, the cooling water is heated by the operation of the engine 10, and the cooling water temperature rises.

  A part of the cooling water flowing through the cooling water flow passage 11 flows into the high temperature side cooling water circuit 31 and passes through the first high temperature side EGR cooler 21 and the second high temperature side EGR cooler 22 located downstream thereof. It returns to the cooling water flow path 11 via. Further, part of the cooling water in the high temperature side cooling water circuit 31 returns to the cooling water flow path 11 via the high temperature side intercooler 71.

  As described above, the high temperature side cooling water circuit 31 is configured so that the temperature of the cooling water does not decrease by being in contact with the high temperature exhaust gas. Further, in the high temperature side intercooler 71, the temperature of the cooling water is prevented from lowering by contacting the supercharged high temperature intake air. Thereby, even when the engine 10 is cold-started, the relatively high-temperature cooling water flows, so that the delay in warming up the engine 10 is improved.

  A part of the cooling water flowing through the cooling water channel 11 flows into the low temperature side cooling water circuit 32 and returns to the cooling water channel 11 via the sub radiator 42, the low temperature side intercooler 72 and the heat exchanger 76. The temperature of the cooling water in the low-temperature side cooling water circuit 32 is lowered by exchanging heat with the outside air by the sub radiator 42. The cooling water whose temperature has been lowered exchanges heat with the intake air supercharged in the low-temperature side intercooler 72, thereby lowering the intake air temperature and raising the cooling water temperature. The temperature of the cooling water exiting the low-temperature side intercooler 72 is further increased by exchanging heat with the cooling water in the high-temperature side cooling water circuit 31 by the heat exchanger 76. The cooling water whose temperature has risen returns to the engine 10 again. The temperature of the cooling water of the high temperature side cooling water circuit 31 is slightly lowered by exchanging heat with the cooling water of the low temperature side cooling water circuit 32 by the heat exchanger 76, but the high temperature supercooled by the high temperature side intercooler 71 is reduced. By performing heat exchange with intake air, the temperature rises and returns to the engine 10 again.

  In this way, in the low temperature side cooling water circuit 32, the temperature of the intake air supercharged by the low temperature side intercooler 72 is lowered by the cooling water whose cooling water temperature has been lowered in the sub radiator 42.

  The cooling water whose temperature has decreased is configured such that the temperature is raised again by passing through the low-temperature intercooler 72 and the heat exchanger 76, and this cooling water returns to the engine 10 again. The high-temperature side cooling water circuit 31 and the low-temperature side cooling water circuit 32 merge and return to the engine 10. At this time, the high temperature side cooling water circuit 31 and the low temperature side cooling water circuit 32 are mixed. With this configuration, in the low temperature side cooling water circuit 32, the temperature of the cooling water that returns to the engine 10 does not decrease, so that the delay in warming up the engine 10 is improved.

  As described above, in the first embodiment of the present invention, the cooling water of the high-temperature side cooling water circuit 31 exiting from the engine 10 and the cooling water of the low-temperature side cooling water circuit 32 exiting from the low-temperature side intercooler 72 are: The heat exchanger 76 is configured to perform heat exchange.

  In particular, since the low-temperature side cooling water circuit 32 reduces the temperature of the cooling water by the sub-radiator 42, the temperature of the supercharged intake air can be reduced, and the generation efficiency of the engine can be improved while generating NOx. Can be suppressed.

  Since the temperature of the cooling water in the low temperature side cooling water circuit 32 returning to the engine 10 rises by passing through the heat exchanger 76, the warm-up delay of the engine 10 is improved. Since the temperature of the cooling water in the high temperature side cooling water circuit 31 flowing through the high temperature side intercooler 71 is lowered by passing through the heat exchanger 76, the intake air temperature can be lowered in the high temperature side intercooler 71. The cooling water exiting the high temperature side intercooler 71 merges with the cooling water in the low temperature side cooling water circuit 32 before the engine 10 and flows to the engine 10, so that the temperature of the cooling water flowing to the engine 10 rises and the engine 10 The warm-up delay is improved.

  Thereby, the warm-up delay of the engine 10 is improved even when the engine 10 is cold started.

  Next, a second embodiment of the present invention will be described.

  FIG. 3 is an explanatory diagram of the cooling device 1 centering on the engine 10 according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the description is abbreviate | omitted.

  In the second embodiment, in the low temperature side cooling water circuit 32, the valve 85 is provided on the inlet side of the heat exchanger 76, and the bypass passage 86 that bypasses the heat exchanger 76 is provided. By opening and closing the valve 75, the cooling water of the low-temperature side cooling water circuit 32 flowing through the heat exchanger 76 is controlled.

  Moreover, in 2nd Embodiment, the 1st water temperature meter 81 which detects the water temperature of the cooling water which flows into the heat exchanger 76 from the high temperature side cooling water circuit 31, and the low temperature side cooling water circuit 32 to the heat exchanger 76. And a second water temperature gauge 82 for detecting the temperature of the cooling water flowing in. A controller that controls opening and closing of the valve 85 based on the water temperature TwH of the high-temperature side cooling water circuit 31 detected by the first water temperature gauge 81 and the water temperature TwL of the low-temperature side cooling water circuit 32 detected by the second water temperature gauge 82. 60.

  Next, operation | movement of the cooling device 1 of 2nd Embodiment comprised in this way is demonstrated.

  FIG. 3 is a flowchart of the control of the cooling water circuit executed by the controller 60 according to the second embodiment of the present invention.

  The flowchart of FIG. 3 is executed by the controller 60 when the engine 10 is started.

  First, the controller 60 checks whether or not the coolant temperature has reached the valve opening temperature of the thermostat 44 in the low-temperature side coolant circuit 32 (step S10). When the cooling water temperature does not reach the valve opening temperature of the thermostat 44, it can be determined that the cooling water temperature is in a low state, and therefore malfunction of the first water temperature meter 81 and the second water temperature meter 82 can be determined. In addition, you may confirm not the cooling water temperature but whether the thermostat 44 opened.

  Next, the controller 60 detects the water temperature TwH on the inlet side of the heat exchanger 76 of the high temperature side cooling water circuit 31 from the first water temperature gauge 81. Further, the water temperature TwL on the outlet side of the heat exchanger 76 of the low temperature side cooling water circuit 32 is detected from the second water temperature gauge 82. And it is determined whether water temperature TwL is lower than water temperature TwH (step S20).

  When it determines with water temperature TwL being lower than water temperature TwH, it transfers to step S30 and the controller 60 controls so that the valve | bulb 85 may be opened. Thereby, the cooling water of the low temperature side cooling water circuit 32 comes to pass through the heat exchanger 76, and in the heat exchanger 76, the cooling water of the low temperature side cooling water circuit 32 and the cooling water of the high temperature side cooling water circuit 31 Performs heat exchange. Thereafter, the process proceeds to step S40.

  In step S40, the controller 60 determines whether or not the water temperature TwL is higher than the water temperature TwH. When the water temperature TwL is lower than the water temperature TwH, the process of step S40 is repeated and waits. In this case, the valve 85 remains open, and in the heat exchanger 76, the cooling water in the low temperature side cooling water circuit 32 and the cooling water in the high temperature side cooling water circuit 31 perform heat exchange.

  When it is determined that the water temperature TwL is higher than the water temperature TwH, the process proceeds to step S50, and the controller 60 controls the valve 85 to be closed. Thereby, the cooling water of the low temperature side cooling water circuit 32 does not pass through the heat exchanger 76 but passes through the bypass passage 86, and between the cooling water of the high temperature side cooling water circuit 31 flowing through the heat exchanger 76. There is no heat exchange. Thereafter, the process proceeds to step S60.

  In Step S20, when it is determined that the water temperature TwL is equal to or higher than the water temperature TwH, the process proceeds to Step S50 without performing the processing of Steps S30 and S40, that is, without opening the valve 85, and the controller 60 Control to close.

  In step S60, the controller 60 determines whether or not the operation of the engine 10 has been stopped. If the engine 10 is in operation, the process returns to step 20 and the process is repeated. When the operation of the engine 10 is stopped, the process according to this flowchart is terminated.

  Thus, in the cooling device 1 of the second embodiment, the controller 60 uses the heat exchanger 76 based on the temperature of the water temperature TwL of the low temperature side cooling water circuit 32 and the water temperature TwH of the high temperature side cooling water circuit 31. Then, it is determined whether or not heat exchange is performed by opening and closing the valve 85.

  That is, when the temperature TwL of the cooling water in the low temperature side cooling water circuit 32 flowing into the heat exchanger 76 is lower than the temperature TwH of the cooling water in the high temperature side cooling water circuit 31, heat exchange is performed in the heat exchanger 76. Thereby, the cooling water temperature of the low temperature side cooling water circuit 32 can be raised, and the engine warm-up delay is improved without lowering the temperature of the cooling water flowing into the engine 10. Further, the heat exchange in the heat exchanger 76 can reduce the cooling water temperature of the high temperature side cooling water circuit 31, thereby further cooling the temperature of the intake air supercharged in the high temperature side intercooler 71.

  On the other hand, when the temperature TwH of the cooling water in the high temperature side cooling water circuit 31 is lower than the temperature TwL of the cooling water in the low temperature side cooling water circuit 32 flowing into the heat exchanger 76, the heat exchange in the heat exchanger 76 is performed. Don't do it. Accordingly, heat exchange with the cooling water having a temperature lower than that of the cooling water in the low-temperature side cooling water circuit 32 is not performed, so that the temperature of the cooling water flowing into the engine 10 does not decrease and the delay in warming up the engine is improved. Is done. Moreover, the temperature of the high-temperature side cooling water circuit 31 does not exchange heat with the higher-temperature cooling water, so that the temperature of the intake air supercharged in the high-temperature side intercooler 71 can be further cooled.

  Next, a third embodiment of the present invention will be described.

  FIG. 4 is an explanatory diagram of the cooling device 1 centering on the engine 10 according to the third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the structure same as 1st and 2nd embodiment, and the description is abbreviate | omitted.

  In the third embodiment, a low temperature side third EGR cooler 24 is provided instead of the high temperature side second EGR cooler 22 in the first or second embodiment, and the cooling water of the low temperature side cooling water circuit 32 is provided to this. It was configured to flow in. In addition, the cooling water of the high temperature side cooling water circuit 31 flowing into the first EGR cooler 21 on the high temperature side provided in the EGR circuit 20 and the low temperature side cooling water circuit 32 exiting from the third EGR cooler 24 on the low temperature side. A second heat exchanger 46 that performs heat exchange with the cooling water is provided. As described above, the lower the intake air temperature of the engine 10, the higher the efficiency. Therefore, in order to reduce the exhaust gas temperature recirculated by EGR, the low temperature cooling from the sub-radiator 42 to the third EGR cooler 24 on the low temperature side. It was configured to allow water to flow.

  In the high temperature side cooling water circuit 31, a part of the cooling water sent from the water pump 12 of the engine 10 exits the engine 10 and passes through the second heat exchanger 46 and the high temperature side first EGR cooler 21. Then, it returns to the cooling water flow path 11 of the engine 10 again.

  In the low temperature side cooling water circuit 32, a part of the cooling water that has exited the sub radiator 42 is sent to the third EGR cooler 24 on the low temperature side. The cooling water that has exited the third EGR cooler 24 on the low temperature side returns to the cooling water flow path 11 of the engine 10 again via the second heat exchanger 46.

  The second heat exchanger 46 exchanges heat between the cooling water exiting from the engine 10 in the high temperature side cooling water circuit 31 and the cooling water exiting from the third EGR cooler 24 on the low temperature side in the low temperature side cooling water circuit 32. I do. Similarly to the heat exchanger 76, the second heat exchanger 46 has, for example, a double pipe structure, and the cooling water of the high temperature side cooling water circuit 31 and the cooling water of the low temperature side cooling water circuit 32 are opposed to each other. The heat exchange is performed by configuring as described above.

  Thus, in the third embodiment, the intake pipe 14 is provided with the first EGR cooler 21 on the high temperature side and the third EGR cooler 24 on the low temperature side in order to cool the exhaust gas recirculated by the EGR. This is the same as in the first and second embodiments described above, but the third EGR cooler 24 on the low temperature side is configured to lower the exhaust temperature by the cooling water whose cooling water temperature has decreased in the sub radiator 42. .

  The high temperature side cooling water circuit 31 is configured so that the temperature of the cooling water does not decrease by contacting with the high temperature exhaust gas. Therefore, even when the engine 10 is cold started, the relatively high temperature cooling water flows. The delay in warming up the engine 10 is improved.

  Further, in the low temperature side cooling water circuit 32, the cooling water whose temperature has been lowered by the sub radiator 42 returns to the cooling water flow path 11 via the low temperature side third EGR cooler 24 and the second heat exchanger 46. The cooling water in the low temperature side cooling water circuit 32 is subjected to heat exchange with the exhaust gas in the low temperature side third EGR cooler 24, thereby lowering the exhaust gas temperature and increasing the cooling water temperature. The temperature of the cooling water exiting the third EGR cooler 24 on the low temperature side is further increased by exchanging heat with the cooling water in the high temperature side cooling water circuit 31 in the second heat exchanger 46. The cooling water whose temperature has risen returns to the engine 10 again.

  The cooling water of the high temperature side cooling water circuit 31 and the cooling water of the low temperature side cooling water circuit 32 merge before the engine 10 and return to the engine 10. With this configuration, in the low temperature side cooling water circuit 32, the temperature of the cooling water that returns to the engine 10 does not decrease, so that the delay in warming up the engine 10 is improved.

  Also in the third embodiment, the controller 60 determines whether or not to bypass the second heat exchanger 46 based on the water temperature of the low temperature side cooling water circuit 32 and the water temperature of the high temperature side cooling water circuit 31. May be.

  In the low temperature side cooling water circuit 32, a valve 65 is provided on the inlet side of the second heat exchanger 46, and a bypass passage 66 that bypasses the second heat exchanger 46 is provided. By opening and closing the valve 65, the cooling water of the low-temperature side cooling water circuit 32 flowing through the second heat exchanger 46 is controlled.

  Further, the third water thermometer 61 that detects the temperature of the cooling water flowing into the second heat exchanger 46 from the high temperature side cooling water circuit 31 and the cooling that flows into the second heat exchanger 46 from the low temperature side cooling water circuit 32. And a fourth water temperature meter 62 for detecting the water temperature.

  Similarly to the second embodiment described above, the controller 60 includes the water temperature TwH3 of the high temperature side cooling water circuit 31 detected by the third water temperature gauge 61 and the water temperature TwL4 of the low temperature side cooling water circuit 32 detected by the fourth water temperature gauge 62. Based on the above, the opening and closing of the valve 65 is controlled.

  For example, when the water temperature TwL4 of the low-temperature side cooling water circuit 32 flowing into the second heat exchanger 46 is lower than the water temperature TwH3 of the high-temperature side cooling water circuit 31, the valve is configured to perform heat exchange in the second heat exchanger 46. Switch 65. Thereby, the cooling water temperature of the low temperature side cooling water circuit 32 can be raised, and the engine warm-up delay is improved without lowering the temperature of the cooling water flowing into the engine 10. Moreover, the cooling water temperature of the high temperature side cooling water circuit 31 can be lowered, and the exhaust temperature can be further cooled in the first EGR cooler 21 on the high temperature side.

  On the other hand, when the water temperature TwH3 of the high temperature side cooling water circuit 31 is lower than the water temperature TwL4 of the low temperature side cooling water circuit 32 flowing into the second heat exchanger 46, heat exchange in the second heat exchanger 46 is not performed. The valve 65 is switched as follows. Accordingly, heat exchange with the cooling water having a temperature lower than that of the cooling water in the low-temperature side cooling water circuit 32 is not performed, so that the temperature of the cooling water flowing into the engine 10 does not decrease and the delay in warming up the engine is improved. Is done. Moreover, the exhaust gas in the first EGR cooler 21 on the high temperature side can be further cooled by not performing heat exchange with the cooling water having a higher temperature in the high temperature side cooling water circuit 31.

  As described above, in the third embodiment, not only the temperature of the supercharged intake air is lowered, but the exhaust temperature is lowered by the first EGR cooler 21 on the high temperature side, as in the first and second embodiments. Then, the exhaust temperature can be lowered in the third EGR cooler 24 on the low temperature side by the cooling water in the low temperature side cooling water circuit 32. Even in such a configuration, the temperature of the cooling water that circulates through the high temperature side cooling water circuit 31 and the low temperature side cooling water circuit 32 and returns to the engine 10 is not lowered. Delay in warming up the engine 10 can be improved.

  The embodiment of the present invention has been described above, but the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

1 Cooling device 10 Engine 11 Cooling water flow path 12 Water pump (W / P)
13 Thermostat (T / S)
18 Supercharger (turbine)
20 EGR circuit 21 First EGR cooler (first exhaust cooling device)
High temperature side first EGR cooler [first embodiment, second embodiment, third embodiment]
22 2nd EGR cooler (2nd exhaust cooling device)
High temperature side second EGR cooler [first embodiment, second embodiment]
23 EGR valve 24 Third EGR cooler (third exhaust cooling device)
Low temperature side third EGR cooler [Third embodiment]
30 Cooling water circuit 31 High temperature side cooling water circuit (first cooling water circuit)
32 Low-temperature side cooling water circuit (second cooling water circuit)
41 Radiator (1st radiator)
42 Sub-radiator (second radiator)
60 controller 71 high temperature side intercooler (first intake air cooling system)
72 Low-temperature intercooler (second intake air cooling system)
76 Heat exchanger 81 First water temperature meter 82 Second water temperature meter 85 Valve 86 Bypass passage

Claims (4)

An engine comprising a cooling water circuit through which engine cooling water circulates and a supercharger that supercharges intake air of the engine, the engine intake air cooling device provided in the engine,
The cooling water circuit includes a first cooling water circuit and a second cooling water circuit,
A first intake air cooling device that cools the intake air with the cooling water of the first cooling water circuit, and a second intake air cooling that further cools the intake air cooled by the first intake water cooling device with the cooling water of the second cooling water circuit. An apparatus, and
The first cooling water circuit returns the cooling water from the engine to the engine again through the first intake air cooling device,
The second cooling water circuit returns the cooling water from the engine to the engine again through the second intake air cooling device,
A heat exchanger for exchanging heat between the cooling water exiting from the engine toward the first intake air cooling device and the cooling water exiting from the second intake air cooling device toward the engine; An intake air cooling system for engines. Wherein the first coolant circuit is provided with a first radiator for cooling the cooling water, the second cooling water circuit, a second radiator for cooling the coolant flowing through the second coolant circuit is provided,
2. The engine intake air cooling device according to claim 1, wherein cooling water that has exited from the engine and has been cooled by the second radiator flows through the second intake air cooling device. 3. And the coolant in the first coolant circuit exiting the first intake air cooling device, a cooling water in the second coolant circuit exiting the heat exchanger, and is combined with, to return to the engine The engine intake air cooling device according to claim 1, wherein the intake air cooling device is used. A first water temperature detection unit for detecting the temperature of the cooling water in the first cooling water circuit entering the heat exchanger;
A second water temperature detection unit for detecting the temperature of the cooling water in the second cooling water circuit entering the heat exchanger;
A bypass flow path for bypassing the cooling water of the second cooling water circuit without circulating the heat exchanger;
A valve for controlling whether or not the cooling water of the second cooling water circuit flows to the bypass flow path;
A control device for controlling the operation of the valve;
Further comprising
The control device includes:
When the coolant temperature of the second coolant circuit is lower than the coolant temperature of the first coolant circuit, the coolant of the second coolant circuit is circulated through the heat exchanger. Control the valve,
When the coolant temperature of the first coolant circuit is lower than the coolant temperature of the second coolant circuit, the coolant of the second coolant circuit is bypassed without passing through the heat exchanger. The engine intake air cooling device according to any one of claims 1 to 3, wherein the valve is controlled.

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