Engine cooling device

Abstract

The invention relates to an engine cooling device. The engine cooling device includes: a cylinder block lower portion which is a lower portion of a cylinder block; the cylinder body upper part is the upper part of the cylinder body; a cylinder head of the engine; an exhaust gas cooling unit that cools exhaust gas of the engine; a heat sink that dissipates heat of the coolant; a first path that bypasses the radiator to circulate the coolant through the cylinder block lower portion, the cylinder block upper portion, the cylinder head, and the exhaust cooling portion; a second path that bypasses the block lower portion to circulate the coolant through the radiator, the block upper portion, the cylinder head, and the exhaust cooling portion; and a flow rate control mechanism that increases the flow rate of the coolant flowing through the second path relative to the flow rate of the coolant flowing through the first path.

Description

Technical Field

[0001] The invention relates to an engine cooling device. Background Art

[0002] There is known an engine cooling device that cools an engine by a coolant (see, for example, Japanese Unexamined Patent Application Publication No. 2023-097991). Summary of the Invention

[0003] If the temperature rise of the engine's cylinder block or cylinder head progresses slowly before warm-up is complete, the amount of unburned fuel may increase, resulting in reduced fuel efficiency. Furthermore, after warm-up is complete, if the temperature in the upper portion of the engine's cylinder block, cylinder head, and exhaust cooling section rises excessively, knocking is more likely to occur, resulting in reduced fuel efficiency.

[0004] In view of the foregoing circumstances, an object of the present invention is to provide an engine cooling device that prevents a decrease in fuel efficiency.

[0005] The above-mentioned purpose can be achieved by an engine cooling device, which includes: a lower part of the cylinder block, which is the lower part of the cylinder block of the engine; an upper part of the cylinder block, which is the upper part of the cylinder block; a cylinder head of the engine; an exhaust cooling part, which cools the exhaust of the engine; a radiator, which dissipates heat of the coolant; a first path, which bypasses the radiator to allow the coolant to circulate through the lower part of the cylinder block, the upper part of the cylinder block, the cylinder head and the exhaust cooling part; a second path, which bypasses the lower part of the cylinder block to allow the coolant to circulate through the radiator, the upper part of the cylinder block, the cylinder head and the exhaust cooling part; and a flow control mechanism, which increases the flow rate of the coolant flowing through the second path relative to the flow rate of the coolant flowing through the first path when the temperature of the coolant flowing through the first path is equal to or greater than the warm-up completion temperature, compared with the case where the temperature of the coolant is less than the warm-up completion temperature.

[0006] The engine cooling device may further include an EGR cooler that cools EGR gas of the engine, and each of the first path and the second path may further circulate the coolant through the EGR cooler.

[0007] The first path may allow the coolant, having passed through the exhaust cooling portion and the cylinder head, to flow into the EGR cooler.

[0008] The second path may include: a path circulating the coolant from the radiator to the cylinder block upper portion and the EGR cooler; and a path circulating the coolant from the radiator to the cylinder head and the exhaust cooling portion.

[0009] The flow control mechanism may include a first water pump provided on the first path and a second water pump provided on the second path.

[0010] An engine cooling device that prevents a decrease in fuel efficiency can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like symbols represent like elements, and wherein:

[0012] Figure 1 is an explanatory diagram of the engine cooling device of the first embodiment;

[0013] Figure 2 is an explanatory diagram of the engine cooling device of the first embodiment;

[0014] Figure 3 is an explanatory diagram of the engine cooling device of the first embodiment;

[0015] Figure 4 is an explanatory diagram of an engine cooling device according to a second embodiment;

[0016] Figure 5 is an explanatory diagram of an engine cooling device according to a second embodiment;

[0017] Figure 6 is an explanatory diagram of an engine cooling device according to a third embodiment;

[0018] Figure 7 is an explanatory diagram of an engine cooling device according to a third embodiment;

[0019] Figure 8 is an explanatory diagram of an engine cooling device according to a fourth embodiment; and

[0020] Figure 9 It is an explanatory diagram of an engine cooling device according to a fourth embodiment. DETAILED DESCRIPTION

[0021] First embodiment

[0022] Figures 1 to 3This is an explanatory diagram of an engine cooling device 1 according to a first embodiment. The engine cooling device 1 is to be installed, for example, on a vehicle. The engine cooling device 1 includes a lower block 11, an upper block 12, a cylinder head 13, an exhaust gas cooler 14, an EGR cooler 21, an EGR valve 22, a throttle body 23, a radiator 30, a heater core 31, an on / off valve 32, an oil cooler 33, water pumps P1 and P2, temperature sensors S1 and S2, and an electronic control unit (ECU) 100. The lower block 11 is the lower portion of the engine's cylinder block. The upper block 12 is the upper portion of the engine's cylinder block. The cylinder liners in the lower block 11, through which coolant flows, and the cylinder liners in the upper block 12, through which coolant flows, are separate from each other. The cylinder head 13 is fixed to the upper portion of the upper block 12. The exhaust gas cooler 14 is provided on the outer periphery of the exhaust manifold connected to the cylinder head 13. As the coolant flows through the exhaust cooling portion 14, heat exchange is performed between the coolant and the exhaust gas, thereby cooling the exhaust gas. The EGR cooler 21 is disposed on the outer periphery of the exhaust gas recirculation (EGR) pipe. As the coolant flows within the EGR cooler 21, heat exchange is performed between the coolant and the EGR gas, thereby cooling the EGR gas. The EGR cooler 21 is connected to the cylinder block upper portion 12. The EGR valve 22 regulates the flow rate of the EGR gas. The throttle body 23 is the main body of the intake valve that regulates the amount of intake air. The radiator 30 promotes heat exchange between the outside air and the coolant to cool the coolant. The heater core 31 promotes heat exchange between the air in the vehicle cabin and the coolant to heat the interior of the vehicle cabin. The switching valve 32 allows or blocks the coolant from flowing into the heater core 31. The oil cooler 33 cools the engine oil through heat exchange between the coolant and the engine oil.

[0023] ECU 100 is an electronic control unit that includes an arithmetic processing circuit that performs various types of arithmetic processing related to vehicle driving control, and a memory that stores programs or data used for control. ECU 100 obtains coolant temperature based on temperature sensors S1 and S2. ECU 100 controls water pumps P1 and P2 and on / off valve 32. It should be noted that water pumps P1 and P2 are electrically operated. Water pumps P1 and P2 are examples of flow control mechanisms. Water pump P1 is an example of a first water pump. Water pump P2 is an example of a second water pump.

[0024] Path 61 connects to the lower cylinder block 11. A water pump P1 is provided on path 61. Water pump P1 pumps coolant to the lower cylinder block 11 via path 61. Path 62 provides communication between the lower cylinder block 11 and the exhaust cooling section 14. Path 63 provides communication between the lower cylinder block 11 and the exhaust cooling section 14 via the oil cooler 33. Path 64 provides communication between the exhaust cooling section 14 and the cylinder head 13. Path 65 provides communication between the cylinder head 13 and the upper cylinder block 12. Path 66 provides communication between the EGR cooler 21 and path 61 via the EGR valve 22 and the throttle body 23. Path 67 branches from path 66 between the EGR cooler 21 and the EGR valve 22 to connect to path 61. Path 71 provides communication between the exhaust cooling section 14 and the radiator 30. Path 68 branches from path 71 to connect to the EGR cooler 21. Path 72 provides communication between the radiator 30 and the upper cylinder block 12. The water pump P2 is provided on the path 72. The water pump P2 pumps the coolant to the cylinder upper portion 12 via the path 72. The temperature sensor S2 is provided on the path 72.

[0025] Path 81 provides communication between the exhaust cooling portion 14 and path 61. The on-off valve 32 and heater core 31 are provided on path 81. A temperature sensor S1 is provided on path 81 between the exhaust cooling portion 14 and the on-off valve 32. It should be noted that, in more detail, temperature sensor S1 is provided on a path (not shown) that bypasses the on-off valve 32 and heater core 31 and provides communication between path 81 and path 61. Therefore, even when the on-off valve 32 is closed, temperature sensor S1 detects the temperature of the coolant from the exhaust cooling portion 14. Thus, temperature sensor S1 detects the temperature of the coolant circulating through the first path, which will be described in detail later.

[0026] Figure 1 1 shows the circulation state of the coolant when the temperature of the coolant detected by the temperature sensor S1 is lower than the warm-up completion temperature. Before the warm-up is completed, the ECU 100 drives the water pump P1 and stops the water pump P2. Figure 1In this state, the coolant flow rate in the path indicated by the solid line is large, and the coolant flow rate in the path indicated by the dashed line is small. In this state, the coolant flows into the lower cylinder portion 11 via path 61. A portion of the coolant that has flowed into the lower cylinder portion 11 flows into the exhaust cooling unit 14 via path 62. A portion of the coolant that has flowed into the lower cylinder portion 11 flows into the oil cooler 33 and the exhaust cooling unit 14 via path 63. A portion of the coolant that has flowed into the exhaust cooling unit 14 flows into the cylinder head 13, the upper cylinder portion 12, and the EGR cooler 21 via paths 64 and 65. A portion of the coolant that has flowed into the exhaust cooling unit 14 flows into the EGR cooler 21 via a portion of path 71 and path 68. A portion of the coolant that has flowed into the EGR cooler 21 flows through the EGR valve 22 and the throttle body 23 via path 66 to flow into path 61. A portion of the coolant that has flowed into the EGR cooler 21 flows into path 61 via path 67. Paths 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , and a portion of path 71 are examples of a first path.

[0027] In the exhaust cooling section 14, the coolant's temperature rises as it passes through the exhaust gas. The high-temperature coolant, having risen in temperature as described above, flows into the cylinder head 13, the cylinder block upper section 12, and the cylinder block lower section 11, thereby accelerating the temperature increase in these sections. This prevents an increase in the amount of unburned fuel in the combustion chamber, thereby preventing a decrease in fuel efficiency. Furthermore, the coolant, now high-temperature after passing through the exhaust cooling section 14, the cylinder head 13, and the cylinder block upper section 12, flows into the EGR cooler 21. This accelerates the temperature increase in the EGR cooler 21, thereby preventing the formation of condensed water in the EGR pipe due to the low-temperature coolant flowing into the EGR cooler 21.

[0028] Furthermore, since water pump P2 is stopped, the flow rate of coolant flowing into radiator 30 is reduced, thereby promoting an increase in the temperature of the coolant. Furthermore, coolant flows into EGR valve 22, thereby preventing an excessive temperature increase of EGR valve 22. Coolant flows into throttle body 23, thereby preventing throttle body 23 from freezing.

[0029] Figure 2 FIG1 shows the circulation state of the coolant when the temperature of the coolant detected by the temperature sensor S1 is equal to or greater than the warm-up completion temperature. After the warm-up is completed, the ECU 100 drives the water pumps P1 and P2. In other words, Figure 2 In, with Figure 1In contrast, the flow rate of coolant obtained by water pump P2 increases relative to the flow rate of coolant obtained by water pump P1. Water pump P2 is driven, so that a portion of the coolant that has already flowed into the exhaust cooling portion 14 flows into the radiator 30 via path 71. The coolant is cooled in the radiator 30. The coolant that has already flowed into the radiator 30 flows into the cylinder upper portion 12 via path 72. Therefore, an excessive temperature increase of the cylinder upper portion 12 is prevented. It should be noted that the coolant that has already flowed into the radiator 30 flows back into the radiator 30 via paths 72, 66, 67, 61, 62, 63, and 71. Therefore, paths 72, 66, 67, 61, 62, 63, and 71 are examples of the second path. As described above, there is an overlap between a portion of the first path and a portion of the second path.

[0030] Furthermore, the coolant that has already flowed into the radiator 30 does not flow into the lower cylinder section 11. This prevents the temperature of the lower cylinder section 11 from dropping. This prevents an increase in the amount of unburned fuel in the combustion chamber, thereby preventing a decrease in fuel efficiency. Furthermore, a portion of the coolant that has already been cooled by the radiator 30 flows through the upper cylinder section 12 into the EGR cooler 21, the EGR valve 22, and the throttle body 23. As the coolant flows through the EGR cooler 21 and the EGR valve 22, cooling of the EGR gas is promoted, thereby preventing a decrease in fuel efficiency.

[0031] When there is a heating request, such as Figure 2 As shown, the ECU 100 opens the switching valve 32. Therefore, a portion of the coolant that has flowed into the exhaust cooling portion 14 flows into the heater core 31 via the path 81. In the heater core 31, heat exchange is performed between the coolant and the air in the vehicle cabin, so that the interior of the vehicle cabin is heated. The path 81 is an example of a third path. It should be noted that even in Figure 1 If there is a heating request before the warm-up is completed, the switching valve 32 may be opened to heat the interior of the vehicle cabin.

[0032] Figure 3 1 shows the circulation state of the coolant when the temperature of the coolant detected by the temperature sensor S1 is equal to or greater than the warm-up completion temperature. Figure 3 The coolant temperature detected by the temperature sensor S1 is higher than Figure 2 The situation. Figure 3 In, similar to Figure 2 Drive water pumps P1 and P2, but Figure 3 In the example, the flow rate of coolant obtained by water pump P2 is greater than the flow rate of coolant obtained by water pump P1. Figure 2 Therefore, in Figure 3In this embodiment, the coolant that has passed through the radiator 30 and flowed into the cylinder block upper portion 12 flows into the cylinder head 13 via path 65. The coolant that has flowed into the cylinder head 13 flows into the exhaust cooling portion 14 via path 64. Therefore, excessive temperature increases in the cylinder block upper portion 12, the cylinder head 13, and the exhaust cooling portion 14 can be prevented. For example, the occurrence of knock can be prevented, thereby preventing a decrease in fuel efficiency. In this case, paths 64 and 65 are also included in the second path.

[0033] Furthermore, a portion of the coolant that has been cooled by the radiator 30 flows into the EGR cooler 21, the EGR valve 22, and the throttle body 23 via the cylinder block upper portion 12. This facilitates cooling of the EGR gas, etc. Furthermore, a portion of the coolant that has flowed into the exhaust cooling portion 14 from the cylinder block lower portion 11, the cylinder head 13, and the oil cooler 33 flows into the radiator 30 via the path 71. This facilitates cooling of the coolant.

[0034] Second embodiment

[0035] Figure 4 and Figure 5 1a is an explanatory diagram of the engine cooling device 1a of the second embodiment. Figure 4 and Figure 5 The cylinder block lower portion 11 and the cylinder block upper portion 12 are shown separated. Path 69 provides communication between the EGR cooler 21 and the cylinder block upper portion 12. Path 66 communicates with path 68. Specifically, a temperature sensor S1 is provided on a path (not shown) that bypasses the on-off valve 32 and the heater core 31 to provide communication between path 81 and path 66. Therefore, even when the on-off valve 32 is closed, the temperature sensor S1 can detect the temperature of the coolant from the exhaust gas cooling portion 14.

[0036] Figure 4The figure shows the coolant circulation state when the coolant temperature detected by temperature sensor S1 is less than the warm-up completion temperature. Before warm-up is complete, ECU 100 drives water pump P1 and stops water pump P2. As a result, coolant flows into the lower cylinder section 11 via path 61. A portion of the coolant that has flowed into the lower cylinder section 11 flows into the exhaust cooling section 14 via path 62. A portion of the coolant that has flowed into the lower cylinder section 11 flows into the oil cooler 33 via path 63. A portion of the coolant that has flowed into the oil cooler 33 flows into the exhaust cooling section 14. A portion of the coolant that has flowed into the exhaust cooling section 14 flows into the EGR cooler 21 via a portion of path 71 and path 68. The coolant that has flowed into the EGR cooler 21 flows into the upper cylinder section 12 via path 69. The coolant that has flowed into the upper cylinder section 12 flows into the cylinder head 13 via path 65. The coolant that has flowed into the cylinder head 13 flows into the exhaust cooling section 14 via path 64. Furthermore, a portion of the coolant that has flowed into the exhaust cooling portion 14 flows into the EGR valve 22 and the throttle body 23 via a portion of the path 71, a portion of the path 68, and the path 66. The coolant that has flowed into the EGR valve 22 and the throttle body 23 flows into the cylinder lower portion 11 via the path 66 and the path 61. The paths 61, 62, 63, 64, 65, 66, 67, 68, 69, and a portion of the path 71 are examples of a first path.

[0037] The coolant that has become a high-temperature coolant in the exhaust gas cooling portion 14 flows into the cylinder block upper portion 12, the cylinder head 13, and the cylinder block lower portion 11. Therefore, an increase in the temperature of the cylinder block upper portion 12, the cylinder head 13, and the cylinder block lower portion 11 is promoted. Furthermore, the coolant that has become a high-temperature coolant by flowing through the cylinder head 13 and the exhaust gas cooling portion 14 flows into the EGR cooler 21. Therefore, an increase in the temperature of the EGR cooler 21 is promoted.

[0038] It should be noted that when the pressure losses of the coolant in the cylinder head 13, the exhaust cooling portion 14, the cylinder block upper portion 12, and the EGR cooler 21 are respectively assumed to be R1, R2, R3, and R4 to establish a Wheatstone bridge circuit, When it is closer to 0, the flow rate of the coolant flowing through the radiator 30 when the water pump P2 is stopped can be reduced. Therefore, when each of the above-mentioned pressure losses is adjusted so that the flow rate of the coolant flowing through the radiator 30 is reduced when the water pump P2 is stopped, the temperature increase of the coolant is promoted, and thus the temperature increase of the cylinder lower portion 11, the cylinder upper portion 12, the cylinder head 13, and the EGR cooler 21 is promoted.

[0039] Figure 5The figure shows the coolant circulation state when the coolant temperature detected by temperature sensor S1 is equal to or greater than the warm-up completion temperature. After warm-up is complete, ECU 100 drives water pumps P1 and P2. A portion of the coolant discharged from the exhaust cooling unit 14 flows into the radiator 30 via path 71. The coolant that has flowed into the radiator 30 flows into the upper cylinder block 12. A portion of the coolant that has flowed into the upper cylinder block 12 flows into the cylinder head 13 and the exhaust cooling unit 14 via paths 65 and 64. As described above, a portion of the coolant that has passed through the radiator 30 flows into the upper cylinder block 12, the cylinder head 13, and the exhaust cooling unit 14, preventing excessive temperature increases in these areas. Furthermore, a portion of the coolant that has flowed into the upper cylinder block 12 flows into the EGR cooler 21 via path 69. A portion of the coolant that has flowed into the EGR cooler 21 flows into the EGR valve 22 and the throttle body 23 via path 66. Even in such a situation, a decrease in fuel efficiency is prevented. Paths 64, 65, 68, 69, 71, and 72 are examples of the second path. Figure 5 As shown, the ECU 100 opens the on-off valve 32. As a result, the interior of the vehicle cabin is heated.

[0040] Third embodiment

[0041] Figure 6 and Figure 7 This is an explanatory diagram of the engine cooling device 1b of the third embodiment. Path 61a communicates with path 72. Specifically, a portion of path 61a downstream of water pump P1 communicates with a portion of path 72 downstream of water pump P2. Water pump P1 is disposed on path 61a. Path 61b provides communication between the cylinder lower portion 11 and path 61a. Specifically, path 61b communicates with a portion of path 61a upstream of water pump P1. Path 61b has an orifice 61c configured to reduce the flow rate of coolant.

[0042] Figure 6The figure shows the coolant circulation state when the coolant temperature detected by temperature sensor S1 is less than the warm-up completion temperature. Before warm-up is completed, ECU 100 drives water pump P1 and stops water pump P2. The coolant flows into the upper cylinder portion 12 via path 61a and a portion of path 72. A portion of the coolant that has already flowed into the upper cylinder portion 12 flows into the EGR cooler 21. A portion of the coolant that has already flowed into the EGR cooler 21 flows into the EGR valve 22 and throttle body 23 via path 66 to flow to path 61a. A portion of the coolant that has already flowed into the EGR cooler 21 flows into path 61a via path 67. A portion of the coolant that has already flowed into the upper cylinder portion 12 flows into the cylinder head 13 and the exhaust cooling portion 14 via paths 65 and 64. Paths 61a, 61b, 62, 63, 64, 65, 66, 67, and a portion of path 72 are examples of the first path.

[0043] The coolant that has flowed into the exhaust cooling section 14 flows into the lower cylinder section 11 via paths 62 and 63. The coolant that has flowed into the lower cylinder section 11 flows into path 61a via path 61b. As described above, the coolant, which has reached a high temperature in the exhaust cooling section 14, flows into the lower cylinder section 11, the upper cylinder section 12, and the cylinder head 13. This promotes a temperature increase in the lower cylinder section 11, the upper cylinder section 12, and the cylinder head 13. Furthermore, path 61b has an orifice 61c. Consequently, the coolant flow rate through the lower cylinder section 11 is reduced, promoting a temperature increase in the lower cylinder section 11.

[0044] Figure 7 The diagram shows the circulation state of the coolant when the temperature of the coolant detected by the temperature sensor S1 is equal to or greater than the warm-up completion temperature. After the warm-up is completed, the ECU 100 drives the water pumps P1 and P2. A portion of the coolant that has flowed into the exhaust cooling portion 14 flows into the radiator 30 via a path 71. The coolant that has flowed into the radiator 30 flows into the upper cylinder portion 12 via a path 72. The coolant that has passed through the radiator 30 and thus flowed into the upper cylinder portion 12 flows through the cylinder head 13 and the exhaust cooling portion 14. Therefore, an excessive temperature increase of the upper cylinder portion 12, the cylinder head 13, and the exhaust cooling portion 14 is prevented. In addition, the coolant that has flowed into the radiator 30 does not flow into the lower cylinder portion 11. Therefore, a temperature drop in the lower cylinder portion 11 is prevented, thereby preventing a decrease in fuel efficiency. Paths 64, 65, 71, and 72 are examples of the second path.

[0045] The driving force of water pumps P1 and P2 can be adjusted to increase or decrease the flow rate of coolant flowing through path 72 relative to the flow rate of coolant flowing through path 61a. For example, when the temperature detected by temperature sensor S1 is a high temperature, equal to or greater than the warm-up completion temperature and further equal to or greater than the knock-initiating temperature, the flow rate of coolant flowing through path 72 can be increased relative to the flow rate of coolant flowing through path 61a, compared to a case where the temperature detected by temperature sensor S1 is equal to or greater than the warm-up completion temperature and further less than the knock-initiating temperature. This ensures the flow rate of coolant, which has passed through radiator 30 to become low-temperature coolant, to upper cylinder block 12, cylinder head 13, and exhaust cooling unit 14, thereby preventing the occurrence of knock.

[0046] Fourth embodiment

[0047] Figure 8 and Figure 9 This is an explanatory diagram of the engine cooling device 1c of the fourth embodiment. The thermostat 34 is arranged in the path 72. The thermostat 34 is connected to the path 61d. When the temperature of the coolant in the thermostat 34 is lower than the warm-up completion temperature, the coolant flows into the thermostat 34 via the path 61d. When the temperature of the coolant in the thermostat 34 is equal to or higher than the warm-up completion temperature, the coolant flows into the thermostat 34 via the path 61d, and the coolant flows into the thermostat 34 via the path 72. The coolant that has flowed into the thermostat 34 flows into the cylinder upper part 12 via the path 72. In addition, the water pump P3 is arranged on the downstream side of the thermostat 34 in the path 72. The thermostat 34 and the water pump P3 are examples of a flow control mechanism. In the fourth embodiment, a single water pump P3 is provided, and therefore, compared with the case where two water pumps P1 and P2 are provided in the above-mentioned first to third embodiments, power consumption is reduced.

[0048] Figure 8 The figure shows the coolant circulation state when the coolant temperature detected by temperature sensor S1 is less than the warm-up completion temperature. Before warm-up is complete, ECU 100 drives water pump P3, and thermostat 34 closes path 72. Coolant flowing through path 61d flows into thermostat 34 and, via a portion of path 72, flows into upper cylinder section 12. A portion of the coolant that has already flowed into upper cylinder section 12 flows into cylinder head 13, exhaust cooling section 14, and lower cylinder section 11. In other words, the coolant, having reached a high temperature in exhaust cooling section 14, flows into lower cylinder section 11, upper cylinder section 12, and cylinder head 13. This promotes a temperature increase in lower cylinder section 11, upper cylinder section 12, and cylinder head 13. Paths 61d, 61b, 62, 63, 64, 65, 66, 67, and a portion of path 72 are examples of the first path.

[0049] Figure 9The figure shows the coolant circulation state when the coolant temperature detected by temperature sensor S1 is equal to or greater than the warm-up completion temperature. After warm-up is complete, ECU 100 activates water pump P3, and thermostat 34 opens path 72. As a result, coolant that has passed through radiator 30 flows into upper cylinder block 12, cylinder head 13, and exhaust cooling unit 14. Consequently, excessive temperature increases in upper cylinder block 12, cylinder head 13, and exhaust cooling unit 14 are prevented. Paths 64, 65, 71, and 72 are examples of the second path.

[0050] Hereinabove, the embodiment of the present invention has been described in detail, but the present invention is not limited to the specific embodiment. Various modifications and changes can be made without departing from the gist of the present invention described in the claims.

Claims

1. An engine cooling device, comprising: A cylinder lower portion, wherein the cylinder lower portion is the lower portion of the cylinder block of the engine; A cylinder upper portion, wherein the cylinder upper portion is the upper portion of the cylinder body; the cylinder head of the engine; an exhaust cooling unit configured to cool exhaust gas from the engine; a radiator that dissipates heat from the coolant; a first path that bypasses the radiator to circulate coolant through the cylinder block lower portion, the cylinder block upper portion, the cylinder head, and the exhaust cooling portion; a second path that bypasses the cylinder block lower portion to circulate coolant through the radiator, the cylinder block upper portion, the cylinder head, and the exhaust cooling portion; as well as A flow control mechanism, which increases the flow rate of the coolant flowing through the second path relative to the flow rate of the coolant flowing through the first path when the temperature of the coolant flowing through the first path is equal to or greater than the warm-up completion temperature, compared to a case where the temperature of the coolant is less than the warm-up completion temperature.

2. The engine cooling device according to claim 1, further comprising an EGR cooler configured to cool the EGR gas of the engine, wherein Each of the first and second paths further circulates coolant through the EGR cooler.

3. The engine cooling device according to claim 2, wherein: The first path allows the coolant, which has passed through the exhaust cooling portion and the cylinder head, to flow into the EGR cooler.

4. The engine cooling device according to claim 3, wherein: The second path includes: a path for circulating coolant from the radiator to the cylinder block upper portion and the EGR cooler; and a path for circulating coolant from the radiator to the cylinder head and the exhaust cooling portion.

5. The engine cooling device according to claim 4, wherein: The flow control mechanism includes a first water pump provided on the first path and a second water pump provided on the second path.

Images