Vehicle cooling system

Abstract

To provide a cooling system for a vehicle capable of minimizing inflow of high-temperature cooling water from a high-temperature cooling system to a low-temperature cooling system by applying cooling system accessory components of one system for those of two systems.SOLUTION: A first partition plate 51C is disposed in an upstream-side tank 51 and a second partition plate 52C is disposed in a downstream-side tank 52 to partition cooling water circulating in a first cooling water circulation circuit 21 and cooling water circulating in a second cooling water circulation circuit 23. The first cooling water circulation circuit 21 is provided with a degassing tank 56 for storing cooling water. A part of tubes 54 positioned on a boundary between the first cooling water circulation circuit 21 and a second cooling water circulation circuit 23 among the plurality of tubes 54 of the core portion 53 are connected to the second cooling water circulation circuit 23 at upstream-side end portions and connected to the first cooling water circulation circuit 21 at downstream-side end portions. A branch circuit 58 communicated to the second cooling water circulation circuit 23 and the degassing tank 56 is disposed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cooling system for a vehicle. [Background technology]

[0002] Patent Document 1 describes a power cooling device for a hybrid vehicle that includes a radiator having a first coolant circulation passage for cooling an internal combustion engine, a second coolant circulation passage for cooling an electric motor, a first tank that connects a core portion with the first coolant circulation passage and the second coolant circulation passage, and a second tank that separates the first coolant circulation passage from the second coolant circulation passage. Patent Document 1 also describes that a semi-partition plate is provided inside the first tank to separate the first coolant circulation passage from the second coolant circulation passage, except for a communication portion that connects the first coolant circulation passage and the second coolant circulation passage.

[0003] The technology described in Patent Document 1 aims to share a radiator tank, and even if a reserve tank is shared, it is possible to prevent the inflow of cooling water from the internal combustion engine into the cooling system for the electric motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-266855 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 is unable to sufficiently suppress the inflow of high-temperature cooling water from the first cooling water circulation passage constituting the high-temperature cooling system to the second cooling water circulation passage constituting the low-temperature cooling system, and there is a need to minimize the inflow of high-temperature cooling water.

[0006] The present invention has been made in response to the above-mentioned problems, and aims to provide a vehicle cooling system that can combine two cooling system auxiliary components into one system while minimizing the inflow of high-temperature cooling water from the high-temperature cooling system to the low-temperature cooling system. [Means for solving the problem]

[0007] The present invention is a vehicle cooling system comprising: a single radiator having an upstream tank, a downstream tank, and a core portion connecting the upstream tank and the downstream tank; a first coolant circulation circuit through which coolant circulates between an engine and the radiator; and a second coolant circulation circuit through which coolant circulates between the radiator and an electric device whose allowable temperature is lower than the maximum temperature of the coolant circulating in the first coolant circulation circuit, wherein the single radiator cools the coolant circulating in the first coolant circulation circuit and the coolant circulating in the second coolant circulation circuit, wherein the upstream tank has: an inlet of the first cooling water circulation circuit to the radiator, and an inlet of the second cooling water circulation circuit to the radiator; a first partition plate that separates the cooling water circulating in the first cooling water circulation circuit from the cooling water circulating in the second cooling water circulation circuit; and, a second partition plate is provided in the downstream tank to separate the cooling water circulating in the first cooling water circulation circuit from the cooling water circulating in the second cooling water circulation circuit, the first cooling water circulation circuit is provided with a degassing tank for storing cooling water, the core part has a plurality of tubes through which cooling water flows from the upstream tank to the downstream tank, and among the plurality of tubes, some of the tubes located at the boundary between the first cooling water circulation circuit and the second cooling water circulation circuit have their upstream ends connected to the second cooling water circulation circuit and their downstream ends connected to the first cooling water circulation circuit, and are provided with a branch circuit communicating with the second cooling water circulation circuit and the degassing tank. [Effects of the Invention]

[0008] As described above, according to the present invention, it is possible to provide a vehicle cooling system that can combine two cooling system auxiliary components into one system while minimizing the inflow of high-temperature cooling water from the high-temperature cooling system to the low-temperature cooling system. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of a vehicle equipped with a vehicle cooling system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a configuration diagram of a vehicle cooling system according to an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing the flow of cooling water when the engine and the electric water pump of the vehicle cooling system according to one embodiment of the present invention are operating. [Figure 4] FIG. 4 is a diagram showing the flow of the cooling water during the cooling water replenishment work of the vehicle cooling system according to one embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing the flow of air during an air bleeding operation in a vehicle cooling system according to an embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing the flow of cooling water during the operation of draining the cooling water in the vehicle cooling system according to one embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing the flow of cooling water during a cooling water refill operation when a valve is provided at the connection between the branch circuit and the degassing tank in a cooling system for a vehicle according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A vehicle cooling system according to one embodiment of the present invention includes a radiator having an upstream tank, a downstream tank, and a core portion connecting the upstream tank and the downstream tank, a first coolant circulation circuit through which coolant circulates between an engine and the radiator, and a second coolant circulation circuit through which coolant circulates between the radiator and an electric device whose allowable temperature is lower than the maximum temperature of the coolant circulating in the first coolant circulation circuit, and the vehicle cooling system cools the coolant circulating in the first coolant circulation circuit and the coolant circulating in the second coolant circulation circuit using the single radiator, and the upstream tank contains a first coolant circulation circuit through which coolant circulates in the first coolant circulation circuit and the coolant circulating in the second coolant circulation circuit. The downstream tank is provided with a first partition plate separating the coolant circulating in the first coolant circulation circuit from the coolant circulating in the second coolant circulation circuit, the downstream tank is provided with a second partition plate separating the coolant circulating in the first coolant circulation circuit from the coolant circulating in the second coolant circulation circuit, the first coolant circulation circuit is provided with a degassing tank for storing coolant, the core part has a plurality of tubes through which coolant flows from the upstream tank to the downstream tank, some of the plurality of tubes located at the boundary between the first coolant circulation circuit and the second coolant circulation circuit have their upstream ends connected to the second coolant circulation circuit and their downstream ends connected to the first coolant circulation circuit, and are provided with a branch circuit communicating with the second coolant circulation circuit and the degassing tank. Thus, the vehicle cooling system according to one embodiment of the present invention can minimize the inflow of high-temperature coolant from the high-temperature cooling system to the low-temperature cooling system while consolidating two systems of cooling system accessories into one system. [Example]

[0011] A vehicle cooling system according to an embodiment of the present invention will now be described with reference to the drawings, in which: Figures 1 to 7 are diagrams showing a vehicle cooling system according to an embodiment of the present invention.

[0012] 1, a vehicle 1 includes an engine (referred to as ENG in the drawing) 2, a transmission (referred to as T / M in the drawing) 3, and an electric motor (referred to as MGU in the drawing) 4.

[0013] The engine 2 is an internal combustion engine that uses gasoline or diesel fuel and generates driving force (engine torque) for traveling. Inside the engine 2, a water jacket (not shown) is provided through which cooling water flows.

[0014] The transmission 3 is connected to the engine 2 and transmits the driving force (engine torque) generated by the engine 2. The transmission 3 is equipped with a speed change mechanism (not shown), and changes the speed of the rotation transmitted from the engine 2 by the speed change mechanism and transmits it to drive wheels (not shown).

[0015] The electric motor 4 is electrically connected to a battery (not shown) via an inverter 5. The electric motor 4 is built into a portion of the transmission 3 subsequent to the speed change mechanism. The driving force (motor torque) for running generated by the electric motor 4 is transmitted to the drive wheels without passing through the speed change mechanism of the transmission 3.

[0016] The electric motor 4 is provided with an oil cooler (denoted as O / C in the drawing) 4A, which cools the oil circulating inside the electric motor 4 by heat exchange with cooling water.

[0017] The vehicle 1 is equipped with one radiator 50. The radiator 50 cools the coolant by heat exchange with the airflow while the vehicle is running. The radiator 50 is equipped with a high-temperature section 50H that cools the relatively high-temperature coolant taken in from the engine 2, and a low-temperature section 50L that cools the relatively low-temperature coolant taken in from the oil cooler 4A.

[0018] The vehicle 1 is equipped with a first coolant circulation circuit 21. The first coolant circulation circuit 21 connects the engine 2 and a radiator 50, and circulates coolant between the engine 2 and the radiator 50. The radiator 50 cools the coolant circulating through the first coolant circulation circuit 21.

[0019] The first coolant circulation circuit 21 includes a feed passage 21A that feeds coolant from the engine 2 to the radiator 50, and the feed passage 21A is connected to a tank 51 upstream of the radiator 50.

[0020] The first coolant circulation circuit 21 includes a return passage 21B that returns the coolant cooled by the radiator 50 to the engine 2, and the return passage 21B is connected to a tank 52 downstream of the radiator 50.

[0021] The vehicle 1 is equipped with a mechanical water pump (denoted as WP in the drawing) 32. The water pump 32 is provided at the end of the return passage 21B on the engine 2 side, and is driven by the engine 2 to send the cooling water drawn from the return passage 21B to the engine 2.

[0022] A thermostat 33 is provided between the engine 2 and the feed passage 21A. The thermostat 33 closes when the temperature of the coolant is lower than a predetermined temperature, thereby preventing the coolant from circulating in the first coolant circulation circuit 21. The thermostat 33 opens when the temperature of the coolant exceeds the predetermined temperature, thereby allowing the coolant to circulate in the first coolant circulation circuit 21. That is, when the thermostat 33 is open, the coolant sent to the engine 2 by the water pump 32 is discharged from the engine 2 after cooling the engine 2. The coolant then passes through the feed passage 21A and is introduced into the radiator 50, where it is cooled, and then returned to the water pump 32 through the return passage 21B.

[0023] The vehicle 1 is equipped with an auxiliary cooling water circulation circuit 22. A heater core 31 and an EGR cooler 30 are connected to the engine 2 via the auxiliary cooling water circulation circuit 22. The heater core 31 heats the passenger compartment (not shown) by exchanging heat with high-temperature cooling water introduced from the engine 2. The EGR cooler 30 cools the exhaust gas emitted from the engine 2 by exchanging heat with the cooling water. The exhaust gas cooled by the EGR cooler 30 is sent to the intake path of the engine 2.

[0024] The auxiliary equipment cooling water circulation circuit 22 has a feed passage 22A that sends cooling water from the engine 2 to the heater core 31, a feed passage 22B that sends cooling water from the engine 2 to the EGR cooler 30, and a return passage 22C that returns cooling water from the heater core 31 and the EGR cooler 30 to the engine 2. The return passage 22C combines the cooling water from the heater core 31 and the cooling water from the EGR cooler 30. The upstream ends of the feed passages 22A and 22B are connected to the engine 2 without passing through the thermostat 33. The downstream end of the return passage 22C is connected to the suction side of the water pump 32. Therefore, while the engine 2 is operating, cooling water always circulates through the auxiliary equipment cooling water circulation circuit 22, regardless of whether the thermostat 33 is open or closed.

[0025] The vehicle 1 is provided with a second coolant circulation circuit 23. The oil cooler 4A is connected to a radiator 50 via the second coolant circulation circuit 23. The radiator 50 cools the coolant circulating through the second coolant circulation circuit 23.

[0026] The second coolant circulation circuit 23 has a feed passage 23A that sends coolant from the oil cooler 4A to the radiator 50, and a return passage 23B that returns the coolant from the radiator 50 to the oil cooler 4A. An electrically operated electric water pump (referred to as EWP in the figure) 37 and an inverter (referred to as INV in the figure) 5 are provided in the return passage 23B. The coolant circulating through the second coolant circulation circuit 23 cools the oil in the oil cooler 4A and the inverter 5.

[0027] Therefore, in the second coolant circulation circuit 23, coolant circulates between the oil cooler 4A and the inverter 5 and the radiator 50. The oil cooler 4A and the inverter 5 are electrical devices whose allowable temperature is lower than the maximum temperature of the coolant circulating in the first coolant circulation circuit 21.

[0028] The radiator 50 is formed with an inlet 51A for the first coolant circulation circuit 21 and an inlet 51B for the second coolant circulation circuit 23. The radiator 50 is formed with an outlet 52A for the first coolant circulation circuit 21 and an outlet 52B for the second coolant circulation circuit 23.

[0029] 2, the radiator 50 has an upstream tank 51 into which the coolant enters, a downstream tank 52 from which the coolant exits, and a core portion 53 that connects the upstream tank 51 and the downstream tank 52. The upstream tank 51 and the downstream tank 52 are configured to temporarily store the coolant, and are connected to one end and the other end of the core portion 53, respectively. The core portion 53 cools the coolant by exchanging heat with the airflow while the vehicle is traveling.

[0030] The upstream tank 51 is formed with an inlet 51A to the radiator 50 of the first coolant circulation circuit 21 and an inlet 51B to the radiator 50 of the second coolant circulation circuit 23. The downstream tank 52 is formed with an outlet 52A of the radiator 50 for the first coolant circulation circuit 21 and an outlet 52B of the radiator 50 for the second coolant circulation circuit 23.

[0031] The upstream tank 51 is provided with a first partition plate 51C that separates the coolant circulating through the first coolant circulation circuit 21 from the coolant circulating through the second coolant circulation circuit 23. By providing the first partition plate 51C in the upstream tank 51, a high-temperature side space 51H in which the coolant circulating through the first coolant circulation circuit 21 is temporarily stored, and a low-temperature side space 51L in which the coolant circulating through the second coolant circulation circuit 23 is temporarily stored.

[0032] The downstream tank 52 is provided with a second partition plate 52C that separates the coolant circulating through the first coolant circulation circuit 21 from the coolant circulating through the second coolant circulation circuit 23. By providing the second partition plate 52C in the downstream tank 52, a high-temperature side space 52H in which the coolant circulating through the first coolant circulation circuit 21 is temporarily stored, and a low-temperature side space 52L in which the coolant circulating through the second coolant circulation circuit 23 is temporarily stored. The second partition plate 52C is provided below the first partition plate 51C in the up-down direction.

[0033] An openable and closable drain cock 57 is provided at the bottom of the low-temperature space 52L of the downstream tank 52. When the cooling water is to be removed, the cooling water can be discharged from the drain cock 57 by opening the drain cock 57.

[0034] The core section 53 has a plurality of tubes 54 through which cooling water flows from the upstream tank 51 to the downstream tank 52. The plurality of tubes 54 are arranged generally horizontally and parallel to one another. Fins 53A are provided on the surfaces of the tubes 54 to increase the contact area with the wind generated by running the vehicle.

[0035] The high-temperature side spaces 51H, 52H in the radiator 50 and the tubes 54 communicating therewith constitute a high-temperature section 50H of the radiator 50. The high-temperature section 50H also constitutes a part of the first coolant circulation circuit 21. The low-temperature side spaces 51L, 52L in the radiator 50 and the tubes 54 communicating therewith constitute a low-temperature section 50L of the radiator 50. The low-temperature section 50L also constitutes a part of the second coolant circulation circuit 23.

[0036] One degassing tank 56 is connected to the high-temperature section 50H of the radiator 50. In other words, the degassing tank 56 is provided in the first coolant circulation circuit 21. The degassing tank 56 stores replenishment coolant. The degassing tank 56 also separates gas (air mixed in the coolant) from the coolant. A feed passage 21A is connected to the side of the bottom of the degassing tank 56. The degassing tank 56 is connected to the feed passage 21A and the return passage 21B, which communicate with the engine 2. The return passage 21B is connected to a position higher than the connection portion of the degassing tank 56 with the feed passage 21A. In this way, the connection portion 56A of the return passage 21B with the degassing tank 56 is provided at a higher position than the connection portion 56B of the feed passage 21A with the degassing tank 56.

[0037] As described above, in this embodiment, one radiator 50 cools the coolant circulating through the first coolant circulation circuit 21 and the coolant circulating through the second coolant circulation circuit 23. Therefore, the radiator 50, which is a cooling accessory, can be shared by both the first coolant circulation circuit 21 and the second coolant circulation circuit 23, thereby reducing the number of cooling system accessories from two systems to one. Furthermore, the relatively high-temperature coolant discharged from the engine 2 and the relatively low-temperature coolant discharged from the oil cooler 4A and the inverter 5 can be cooled using one radiator 50, thereby simplifying the structure and making it compact.

[0038] Furthermore, since the upstream tank 51 includes the first partition plate 51C that separates the first coolant circulation circuit 21 and the second coolant circulation circuit 23, it is possible to prevent the high-temperature coolant circulating through the first coolant circulation circuit 21 from mixing with the low-temperature coolant circulating through the second coolant circulation circuit 23. Since the downstream tank 52 includes the second partition plate 52C that separates the first coolant circulation circuit 21 and the second coolant circulation circuit 23, it is possible to prevent the high-temperature coolant circulating through the first coolant circulation circuit 21 from mixing with the low-temperature coolant circulating through the second coolant circulation circuit 23.

[0039] If the first coolant circulation circuit 21 and the second coolant circulation circuit 23 were completely blocked, it would be impossible to replenish the second coolant circulation circuit 23 with coolant from the degassing tank 56, and therefore a degassing tank would be required for the second coolant circulation circuit 23 in addition to the degassing tank 56 provided for the first coolant circulation circuit 21. If a degassing tank were provided for the second coolant circulation circuit 23 as well, the structure would become complex and large.

[0040] Therefore, in this embodiment, a branch circuit 58 is provided that communicates with the second coolant circulation circuit 23 and the degassing tank 56. The branch circuit 58 is connected to the return passage 23B that communicates with the electric water pump 37. By providing the branch circuit 58, coolant can be replenished from the degassing tank 56 to the second coolant circulation circuit 23. Therefore, the degassing tank 56, which is a cooling accessory, can be shared by both the first coolant circulation circuit 21 and the second coolant circulation circuit 23, thereby reducing the number of cooling system accessories from two systems to one. The connection portion 56C of the branch circuit 58 to the degassing tank 56 is located higher than the connection portion 56B of the feed passage 21A and the connection portion 56A of the return passage 21B. Therefore, the branch circuit 58 is connected to the degassing tank 56 at a position above the liquid level of the coolant stored in the degassing tank 56.

[0041] In this embodiment, among the multiple tubes 54 in the core portion 53, some of the tubes 54 located at the boundary between the first coolant circulation circuit 21 and the second coolant circulation circuit 23 constitute a communicating tube 54R that communicates the second coolant circulation circuit 23 and the first coolant circulation circuit 21. That is, some (one in this embodiment) of the existing multiple tubes 54 function as the communicating tube 54R. An upstream end (an end on the upstream tank 51 side) of the communicating tube 54R is connected to the second coolant circulation circuit 23 side (low-temperature side space 51L) of the upstream tank 51. A downstream end (an end on the downstream tank 52 side) of the communicating tube 54R is connected to the first coolant circulation circuit 21 side (high-temperature side space 51H) of the downstream tank 52. This allows some of the coolant to circulate between the low-temperature side space 51L of the upstream tank 51 and the high-temperature side space 51H of the downstream tank 52 through the communicating tube 54R.

[0042] Here, the flow direction of the coolant in the communicating tube 54R during engine operation varies depending on the pressure difference between the pressure in the first coolant circulation circuit 21 and the pressure in the second coolant circulation circuit 23. When the pressure in the first coolant circulation circuit 21 is higher than the pressure in the second coolant circulation circuit 23, some of the coolant in the high-temperature cooling system (high-temperature side space 51H) flows into the low-temperature cooling system (low-temperature side space 51L). However, because the communicating tube 54R is only one of the multiple tubes 54 (one tube in this embodiment), the amount of coolant passing through the communicating tube 54R is minimized. Furthermore, depending on the pressure difference between the pressure in the first coolant circulation circuit 21 and the pressure in the second coolant circulation circuit 23, high-temperature coolant does not flow from the high-temperature cooling system to the low-temperature cooling system. Therefore, the inflow of high-temperature coolant from the high-temperature cooling system to the low-temperature cooling system can be minimized.

[0043] The flow of coolant during operation of the engine 2 and the electric water pump 37 will be described with reference to Figure 3. In Figure 3, solid arrows indicate the flow of coolant in the first coolant circulation circuit 21, and dashed arrows indicate the flow of coolant in the second coolant circulation circuit 23.

[0044] 3, when engine 2 and electric water pump 37 are operating, water pump 32 causes coolant to circulate in first coolant circulation circuit 21 between high-temperature section 50H of radiator 50 and engine 2 through feed passage 21A and return passage 21B. Coolant also circulates between radiator 50 and degas tank 56 through feed passage 21A and return passage 21B.

[0045] Furthermore, when engine 2 and electric water pump 37 are operating, electric water pump 37 causes the coolant to circulate through feed passage 23A and return passage 23B in second coolant circulation circuit 23 between low-temperature section 50L of radiator 50 and oil cooler 4A and inverter 5. A portion of the coolant passing through return passage 23B flows into branch circuit 58.

[0046] In addition, depending on the pressure difference between the pressure in the first cooling water circulation circuit 21 and the pressure in the second cooling water circulation circuit 23, a portion of the cooling water flows between the low-temperature side space 51L of the upstream tank 51 and the high-temperature side space 51H of the downstream tank 52 through the communicating tube 54R.

[0047] The branch circuit 58 is connected to the degassing tank 56 at a position above the liquid level of the coolant stored in the degassing tank 56. Specifically, with the position of the connection 56C of the branch circuit 58 relative to the degassing tank 56 as a reference, if the liquid level of the coolant stored in the degassing tank 56 is defined as liquid level H and the liquid level of the coolant in the branch circuit 58 is defined as liquid level h, the liquid level H and the liquid level h are generally the same. The connection 56B of the feed passage 21A and the connection 56A of the return passage 21B are located at a position lower than the liquid level H of the degassing tank 56. Furthermore, the connection 56C of the branch circuit 58 is located at a position higher than the liquid level H of the degassing tank 56. This prevents the coolant from flowing back from the branch circuit 58 to the degassing tank 56 when the engine 2 is running. Furthermore, it prevents the coolant from flowing from the degassing tank 56 into the branch circuit 58 when the engine is running. The liquid level position H and the liquid level position h are equal in a static state, but are different in a dynamic state. The liquid level position H and the liquid level position h are set to values ​​with a sufficient margin.

[0048] The flow of the coolant during the coolant replenishment work will be described with reference to Fig. 4. In Fig. 4, solid arrows indicate the flow of the coolant in the first coolant circulation circuit 21 and the second coolant circulation circuit 23.

[0049] As shown in FIG. 4 , when the radiator 50 is refilled with coolant through the degassing tank 56, the coolant refilled in the degassing tank 56 is supplied from the degassing tank 56 to the first coolant circulation circuit 21 through the feed passage 21A. The coolant supplied to the first coolant circulation circuit 21 returns to the degassing tank 56 through the return passage 21B while pushing out air. The coolant supplied to the first coolant circulation circuit 21 is also supplied to the second coolant circulation circuit 23 through the communication tube 54R. The coolant supplied to the second coolant circulation circuit 23 circulates through the second coolant circulation circuit 23 while pushing out air. Note that the coolant refilling operation is performed with the engine 2 and electric water pump 37 stopped, but because the thermostat 33 is slightly open, the coolant can flow through the gaps between the impellers of the water pump 32 and the electric water pump 37.

[0050] The air flow during the air bleeding operation will be described with reference to Figure 5. In Figure 5, the dashed arrows indicate the air flow in the first coolant circulation circuit 21 and the second coolant circulation circuit 23. Note that the air bleeding operation is performed separately from the coolant refilling operation.

[0051] As shown in Figure 5, when bleeding air from the radiator 50, the air in the second coolant circulation circuit 23 passes through the communication tube 54R and moves into the first coolant circulation circuit 21. The air that has moved into the first coolant circulation circuit 21 then moves into the degassing tank 56. The air in the second coolant circulation circuit 23 passes through the branch circuit 58 and moves to the degassing tank 56. The air bleeding operation is performed while the engine 2 and electric water pump 37 are operating. The thermostat 33 is slightly open even when the engine 2 starts operating, and gradually opens as the engine 2 operates for an extended period of time. The flow direction of the coolant during the air bleeding operation is the same as the flow direction of the air.

[0052] The flow of cooling water during the cooling water draining operation will be described with reference to Fig. 6. In Fig. 6, solid arrows indicate the flow of cooling water in the first cooling water circulation circuit 21 and the second cooling water circulation circuit 23.

[0053] As shown in Figure 6, when draining the coolant in the radiator 50, the drain cock 57 is opened. This causes the coolant in the second coolant circulation circuit 23 to pass through the drain cock 57 and be discharged to the outside of the radiator 50. The coolant in the first coolant circulation circuit 21 passes through the communication tube 54R into the second coolant circulation circuit 23 and is then discharged to the outside of the radiator 50 through the drain cock 57. The coolant draining operation is performed with the engine 2 and electric water pump 37 stopped, but because the thermostat 33 is slightly open, the coolant can flow through the gaps between the water pump 32 and the impellers of the electric water pump 37. Because all passages, including the return passage 23B, are actually located above the drain cock 57, no coolant remains in the return passage 23B, etc.

[0054] 7, a description will be given of the flow of coolant during coolant replenishment work when a valve 59 is provided at a connection 56C between the branch circuit 58 and the degassing tank 56. In Fig. 7, solid arrows indicate the flow of coolant in the first coolant circulation circuit 21 and the second coolant circulation circuit 23.

[0055] 7, a valve 59 may be provided at a connection 56C between the branch circuit 58 and the degassing tank 56. The valve 59 is opened when the radiator 50 is replenished with coolant via the degassing tank 56, and is closed otherwise. The connection 56C is located at the bottom of the side of the degassing tank 56.

[0056] When the radiator 50 is refilled with coolant through the degassing tank 56, the coolant refilled in the degassing tank 56 is supplied from the degassing tank 56 through the feed passage 21A to the first coolant circulation circuit 21. The coolant supplied to the first coolant circulation circuit 21 then returns to the degassing tank 56 through the return passage 21B while pushing out air. The coolant supplied to the first coolant circulation circuit 21 is also supplied to the second coolant circulation circuit 23 through the communicating tube 54R. The coolant supplied to the second coolant circulation circuit 23 circulates through the second coolant circulation circuit 23 while pushing out air. The coolant refilling operation is performed while the engine 2 and electric water pump 37 are stopped, but because the thermostat 33 is slightly open, the coolant can flow through the gaps between the impellers of the water pump 32 and the electric water pump 37. Furthermore, since the valve 59 is opened during the cooling water refilling operation, the cooling water refilled in the degassing tank 56 is supplied from the degassing tank 56 through the branch circuit 58 to the second cooling water circulation circuit 23. Note that the configuration is not limited to the one in which the connection part 56C is disposed at the bottom of the side of the degassing tank 56 and then the valve 59 is provided, and the configuration in which the connection part 56C is disposed at the top of the side of the degassing tank 56 as shown in FIG. 2 may also be such that the valve 59 is provided as shown in FIG.

[0057] As described above, in the vehicle cooling system of this embodiment, the upstream tank 51 is provided with a first partition plate 51C that separates the coolant circulating through the first coolant circulation circuit 21 from the coolant circulating through the second coolant circulation circuit 23, and the downstream tank 52 is provided with a second partition plate 52C that separates the coolant circulating through the first coolant circulation circuit 21 from the coolant circulating through the second coolant circulation circuit 23. In addition, the first coolant circulation circuit 21 is provided with a degassing tank 56 that stores coolant.

[0058] The core section 53 also has a plurality of tubes 54 through which cooling water flows from the upstream tank 51 to the downstream tank 52, and some of the plurality of tubes 54, located at the boundary between the first cooling water circulation circuit 21 and the second cooling water circulation circuit 23, have their upstream ends connected to the second cooling water circulation circuit 23 and their downstream ends connected to the first cooling water circulation circuit 21. The core section 53 also has a branch circuit 58 that communicates with the second cooling water circulation circuit 23 and the degassing tank 56.

[0059] This allows a portion of the cooling water in the second cooling water circulation circuit 23 to pass through the communication tube 54R and circulate through the degassing tank 56. Therefore, the radiator 50 and the degassing tank 56, which are cooling accessories, can be shared by the first cooling water circulation circuit 21 and the second cooling water circulation circuit 23, so that two systems of cooling system accessories can be combined into one system.

[0060] Furthermore, the communicating tube 54R is one of the multiple tubes 54, and the pressure difference between the pressure in the first cooling water circulation circuit 21 and the pressure in the second cooling water circulation circuit 23 prevents high-temperature cooling water from flowing from the high-temperature cooling system to the low-temperature cooling system, thereby minimizing the flow of high-temperature cooling water from the high-temperature cooling system to the low-temperature cooling system.

[0061] As a result, two cooling system auxiliary components can be combined into one system, while minimizing the inflow of high-temperature cooling water from the high-temperature cooling system to the low-temperature cooling system.

[0062] In the vehicle cooling system of this embodiment, the branch circuit 58 is connected to the degassing tank 56 at a position above the liquid level of the cooling water stored in the degassing tank 56 .

[0063] This makes it possible to prevent cooling water from flowing back from the branch circuit 58 to the degassing tank 56 when the engine 2 is running. It also makes it possible to prevent cooling water from flowing from the degassing tank 56 into the branch circuit 58 when the engine is running.

[0064] In the vehicle cooling system of this embodiment, a valve 59 is provided at a connection 56C between the branch circuit 58 and the degassing tank 56.

[0065] Therefore, by keeping the valve 59 closed, it is possible to prevent the cooling water from flowing back from the branch circuit 58 to the degassing tank 56 when the engine 2 is running. Also, by keeping the valve 59 closed, it is possible to prevent the cooling water from flowing from the degassing tank 56 into the branch circuit 58 when the engine 2 is running.

[0066] In addition, even if the liquid level of the cooling water stored in the degassing tank 56 rises or it is difficult to connect the branch circuit 58 above the liquid level of the cooling water stored in the degassing tank 56, backflow of the cooling water can be prevented by keeping the valve 59 closed.

[0067] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0068] 21...First cooling water circulation circuit, 23...Second cooling water circulation circuit, 50...Radiator, 51...Upstream tank, 51C...First partition plate, 52...Downstream tank, 52C...Second partition plate, 53...Core portion, 54...Tube, 54R...Communicating tube, 56...Degas tank, 58...Branch circuit, 59...Valve

Claims

1. a radiator including an upstream tank, a downstream tank, and a core portion connecting the upstream tank and the downstream tank; a first coolant circulation circuit through which coolant circulates between the engine and the radiator; a second coolant circulation circuit through which coolant circulates between the radiator and an electric device whose allowable temperature is lower than the maximum temperature of the coolant circulating in the first coolant circulation circuit, a cooling system for a vehicle in which a single radiator cools a coolant circulating through the first coolant circulation circuit and a coolant circulating through the second coolant circulation circuit, the upstream tank is provided with an inlet of the first cooling water circulation circuit to the radiator, an inlet of the second cooling water circulation circuit to the radiator, and a first partition plate that separates the cooling water circulating in the first cooling water circulation circuit from the cooling water circulating in the second cooling water circulation circuit; the downstream tank is provided with a second partition plate that separates the cooling water circulating through the first cooling water circulation circuit from the cooling water circulating through the second cooling water circulation circuit, The first cooling water circulation circuit is provided with a degassing tank that stores cooling water, the core portion has a plurality of tubes through which cooling water flows from the upstream tank to the downstream tank, Among the plurality of tubes, some of the tubes located at the boundary between the first cooling water circulation circuit and the second cooling water circulation circuit have upstream ends connected to the second cooling water circulation circuit and downstream ends connected to the first cooling water circulation circuit, a branch circuit communicating with the second coolant circulation circuit and the degassing tank;

2. 2. The vehicle cooling system according to claim 1, wherein the branch circuit is connected to the degassing tank at a position above a liquid level of the cooling water stored in the degassing tank.

3. 3. The vehicle cooling system according to claim 1, wherein a valve is provided at a connection between the branch circuit and the degassing tank.

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