ENGINE COOLING DEVICE AND ENGINE SYSTEM

Abstract

An engine cooling device (4), comprising: a pump (5) that delivers coolant from an outlet port (5b) of the pump (5) to an engine (2) and an EGR cooler (3); a radiator (6) which cools the coolant from the engine (2) and the EGR cooler (3), wherein an outlet (6b) for the coolant in the radiator (6) is connected to a suction port (5a) of the pump (5); a flow channel switching unit (7) which is provided in the middle of a flow channel of the cooling water from the engine (2) and from the EGR cooler (3) to the radiator (6); a radiator connection flow channel (15) that connects the flow channel switching unit (7) to the radiator (6); and a first bypass flow channel (16) which connects the flow channel switching unit (7) to the suction port (5a) of the pump (5), characterized by the fact that the flow channel switching unit (7) has: a first valve (20A) that allows the cooling water to flow through the first bypass flow channel (16) when the temperature of the cooling water is lower than a first predetermined temperature, and allows the cooling water to flow through the radiator connection flow channel (15) when the temperature of the cooling water is equal to or higher than the first predetermined temperature; and a second valve (20B) that allows the cooling water to flow through the first bypass flow channel (16) when the temperature of the cooling water is lower than a second predetermined temperature which is higher than the first predetermined temperature, and allows the cooling water to flow through the radiator connection flow channel (15) when the temperature of the cooling water is equal to or higher than the second predetermined temperature, where the number of first valves (20A) is less than the number of second valves (20B), and wherein the second valves (20B) are arranged on both sides of the first valve (20a) in a lateral direction.

Description

[Technical field]

[0001] The present invention relates to an engine cooling device and an engine system. [State of the art]

[0002] JP 2019-35371 A represents the closest prior art and discloses an engine cooling device according to the preamble of claim 1.

[0003] CN 205349500 U shows a multi-stage open-loop thermal controller in which three valves are connected in parallel in a delta arrangement.

[0004] DE 11 2018 000 019 T5 teaches an engine cooling device that has a flow channel switching part between the engine and the radiator. This flow channel switching part has valves that switch between a radiator connection flow channel and a bypass flow channel according to a coolant temperature.

[0005] JP H11-218024 A discloses an engine cooling device with a valve (thermostat) for switching a cooling water circulation channel according to a cooling water temperature. In the engine cooling device of JP H11-218024 A, the valve is closed during engine warm-up (when cooling water is below a predetermined temperature), the cooling water is circulated between the pump and the engine, and the valve is opened when the warm-up is completed (when the cooling water reaches a temperature equal to or higher than the predetermined temperature), thereby circulating the cooling water sequentially through the pump, the engine, and a radiator. [Overview of the invention][Problems to be solved by the invention]

[0006] In an engine system including an engine or internal combustion engine and the previously described engine cooling device, there is a system configured to mix a portion of the exhaust gas discharged from the engine, used as EGR (Exhaust Gas Recirculation) gas, with outside air and recirculate it to the engine, thereby reducing NOx in the exhaust gas. An engine system of this type includes an EGR cooler for cooling the EGR gas. The engine cooling device is further configured to supply cooling water from the pump to both the engine and the EGR cooler.

[0007] However, since the cooling water is not directed to the radiator during the engine warm-up phase, the cooling water pressure tends to rise proportionally to the increase in cooling water temperature. Since the resistance (pressure resistance) of the EGR cooler to the cooling water pressure is often lower than the resistance of the engine, it is not desirable for the cooling water pressure to rise.

[0008] It is also conceivable to reduce the pressure increase in the cooling water by opening the valve at a lower temperature and directing the cooling water to the radiator. However, this approach poses the problem that the engine heats up less, and the engine warm-up phase is prolonged.

[0009] The present invention has been conceived in view of such a problem, and the present invention aims to provide an engine cooling device that protects an EGR cooler and is capable of avoiding prolongation of the warm-up period of the engine, and it is a further object to provide an engine system provided with the engine cooling device. [Means of solving the problem]

[0010] An engine cooling device according to the present invention includes: a pump that supplies cooling water from an outlet port of the pump to an engine and an EGR cooler; a radiator that cools the cooling water from the engine and the EGR cooler, wherein an outlet for the cooling water in the radiator is connected to a suction port of the pump; a flow channel switching unit provided in the middle of a flow channel for the cooling water from the engine and the EGR cooler to the radiator; a radiator connection flow channel connecting the flow channel switching unit and the radiator; and a first bypass flow channel connecting the flow channel switching unit to the suction port of the pump.The flow channel switching unit includes: a first valve that allows the cooling water to flow through the first bypass flow channel when a temperature of the cooling water is lower than a first predetermined temperature, and that allows the cooling water to flow through the radiator connection flow channel when the temperature of the cooling water is equal to or higher than the first predetermined temperature; and a second valve that allows the cooling water to flow through the first bypass flow channel when the temperature of the cooling water is lower than the second predetermined temperature, which is higher than the first predetermined temperature, and allows the cooling water to flow through the radiator connection flow channel when the temperature of the cooling water is equal to or higher than the second predetermined temperature.The number of first valves is smaller than the number of second valves, and the second valves are arranged on both sides of the first valve in a lateral direction.

[0011] An engine system according to the present invention comprises an engine, an EGR cooler and the aforementioned engine cooling device. [Effect of the invention]

[0012] According to the present invention, protection for the EGR cooler can be achieved and it is possible to reduce a prolongation of a warm-up period of the engine. [Brief description of drawings] Fig. 1 is a schematic structural view showing an engine system according to an embodiment of the present invention. Fig.2 is a cross-sectional view showing a state in which a first valve and second valves in the flow passage switching unit in the engine system according to the embodiment of the present invention are closed. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a cross-sectional view showing a state in which the first valve is opened and the second valves are closed in the flow channel switching unit in the engine system according to the embodiment of the present invention. Fig. 5 is a cross-sectional view taken along the line VV in Fig. 4. Fig. 6 is a sectional view showing a state in which the first valve and the second valves in the flow passage switching unit in the engine system according to the embodiment of the present invention are opened. [MODE FOR EXECUTING THE INVENTION]< Motor system >

[0013] With reference to Fig. 1 to Fig. 6, the embodiment of the present invention will be described in detail below. The engine system according to the present embodiment can be used in any commercial vehicle, for example, a garbage truck, a wheel loader, a bulldozer, or the like.

[0014] As in Fig. As shown in Figure 1, the engine system 1 includes an engine or combustion engine 2, an EGR cooler 3, and an engine cooling device 4 for cooling the engine 2 and the EGR cooler 3 with cooling water. The arrows in Fig. 1 indicate the direction in which the cooling water flows in the engine system 1. < Engine >

[0015] The engine 2 includes a cylinder, a cylinder block, a cylinder head, and the like. The cylinder head and the cylinder block are provided with a first cooling flow passage EF through which cooling water flows. The engine 2 is cooled by the cooling water flowing in the first cooling flow passage EF. < EGR cooler >

[0016] The EGR cooler 3 cools the EGR gas, which is part of the exhaust gas discharged from the engine 2. The EGR cooler 3 is provided with a second cooling flow passage CF through which the cooling water flows. The EGR gas flowing through the EGR cooler 3 is cooled by heat exchange with the cooling water flowing in the second cooling flow passage CF. < Engine cooling system >

[0017] The engine cooling device 4 includes a pump 5, a radiator 6, and a flow channel switching unit 7. The engine cooling device 4 of the present embodiment further includes an oil cooler 8. The engine cooling device 4 of the present embodiment further includes a defoaming tank 9. < Pump >

[0018] The pump 5 delivers cooling water from an outlet port 5b of the pump to the engine 2 and to the EGR cooler 3. The outlet port 5b of the pump 5 is connected to an inlet EFa of the first cooling flow passage EF of the engine 2 and to an inlet port CFa of the second cooling flow passage CF of the EGR cooler 3. The pump 5 is driven by power from the engine 2. The pump 5 is always operated when the engine 2 is running. < Radiator >

[0019] The radiator 6 cools the cooling water that has reached a high temperature by heat exchange between the outside air and the cooling water that flows in the first cooling flow passage EF of the engine 2 in the second cooling flow passage CF of the EGR cooler 3 and that has been heated by the engine 2 and the EGR cooler 3.

[0020] An outlet 6b for the cooling water in the radiator 6 is connected to the suction ports 5a of the pump 5. This means that the cooling water cooled in the radiator 6 flows to the pump 5. The outlet 6b for the cooling water in the radiator 6 may, for example, be directly connected to the suction ports 5a of the pump 5, but in the present embodiment, it is connected to the suction ports 5a of the pump 5 via an oil cooler 8, which will be described later.

[0021] The radiator 6 includes a core 11 and an upper tank 12. The core 11 performs heat exchange between the cooling water and the outside air. Specifically, heat exchange is performed between the cooling water flowing in a pipe (not shown) of the core 11 and the outside air in the vicinity of the pipe. The upper tank 12 is provided on an upper side of the core 11, stores the cooling water flowing in from the engine 2 and the EGR cooler 3, and supplies it to the core 11. A radiator cover 13 is detachably provided on the upper tank 12. By removing the radiator cover 13, the cooling water outside a cooling water circulation channel in the engine cooling device 4 can be supplied to the upper tank 12. < Oil cooler >

[0022] The oil cooler 8 cools brake oil used for the brakes of the work vehicle. The oil cooler 8 is connected to the cooling water outlet 6b in the radiator 6. Thus, the cooling water from the radiator 6 passes through the oil cooler 8, and the brake oil can be cooled by performing heat exchange between the cooling water and the brake oil. The cooling water outlet 8b in the oil cooler 8 is connected to the suction ports 5a of the pump 5. Thus, the cooling water flows sequentially through the radiator 6 and the oil cooler 8 and then returns to the pump 5. < Defoaming tank >

[0023] The defoaming tank 9 is connected to the engine 2, the EGR cooler 3, and the upper tank 12. Furthermore, the defoaming tank 9 is connected to the suction ports 5a of the pump 5. The defoaming tank 9 collects the cooling water containing foam from the engine 2, the EGR cooler 3, and the upper tank 12, separates the foam from the cooling water, and removes the foam. The cooling water from which the foam has been removed flows from the defoaming tank 9 to the pump 5. Since the defoaming tank 9 and the upper tank 12 are connected to each other, the pressure of the cooling water in the upper tank 12 and in the defoaming tank 9 is maintained at the same level.

[0024] The defoaming tank 9 has a relief cap 14. The relief cap 14 opens when the pressure of the cooling water in the defoaming tank 9 and in the cooling water circulation channel connected thereto reaches a predetermined pressure, thereby preventing the pressure from becoming excessively high. < Flow channel switching unit >

[0025] The flow channel switching unit 7 is arranged in the center of a channel for the cooling water from the engine 2 and the EGR cooler 3 to the radiator 6, that is, it is arranged between the engine 2 and the EGR cooler 3 and the radiator 6. A radiator connection flow channel 15 is provided between the flow channel switching unit 7 and the radiator 6 to connect them. A first bypass flow channel 16 is provided between the flow channel switching unit 7 and the pump 5 to connect them. Furthermore, a second bypass flow channel 17 is provided between the flow channel switching unit 7 and the oil cooler 8 to connect them.

[0026] The flow channel switching unit 7 separates the flow channel of the cooling water such that the cooling water from the engine 2 and the EGR cooler 3 can flow through the radiator connection flow channel 15 and / or the first and second bypass flow channels 16 and 17.

[0027] As in Fig. 2 and Fig. 3, the flow channel switching unit 7 includes a plurality of valves 20A and 20B and a housing 30 for accommodating the plurality of valves 20A and 20B. < Housing >

[0028] An inlet-side flow channel 31, a first outlet-side flow channel 32 and a second outlet-side flow channel 33 are formed on an inner region of the housing 30. The inlet-side flow channel 31 has an inlet 31a, which is connected to outlets EFb, CFb (see Fig. 1) of the first cooling flow passage EF of the engine 2 and the second cooling flow passage CF of the EGR cooler 3.

[0029] The first outlet-side flow channel 32 has a pump-side outlet port 32a for connecting the first bypass flow channel 16 and an oil cooler-side outlet port 32b for connecting the second bypass flow channel 17. The pump-side outlet port 32a and the oil cooler-side outlet port 32b are spaced apart from each other. In the present embodiment, the pump-side outlet port 32a and the oil cooler-side outlet port 32b are located at both ends of the first outlet-side flow channel 32 (housing 30) in one direction (in Fig.2 a lateral direction). The second output-side flow channel 33 has a radiator-side output port 33a for connecting to the radiator connection flow channel 15. The number of radiator-side output ports 33a may be, for example, one, but in the present embodiment, a plurality of output ports are provided. The plurality of radiator-side output ports 43a are arranged at intervals in the lateral direction. In the Fig. In the housing 30 shown in Figure 2, the number of radiator-side output connections 33a is two.

[0030] The input-side flow channel 31, the first output-side flow channel 32, and the second output-side flow channel 33 may be arranged relative to each other so as to be switchable between a state in which the input-side flow channel 31 and the first output-side flow channel 32 communicate with each other and a state in which the input-side flow channel 31 and the second output-side flow channel 33 communicate with each other by the valves 20A and 20B described later. In the present embodiment, the inlet-side flow channel 31, the second outlet-side flow channel 33 and the first outlet-side flow channel 32 are arranged in sequence from the bottom in a vertical direction (in Fig. 2 and Fig.3 the vertical direction) are arranged, which intersect in the lateral direction in which the pump-side output port 32a and the random-side output port 32b are arranged. The second output-side flow channel 33 is arranged on an upper side of the first output-side flow channel 32 in the vertical direction. In particular, as shown in Fig.3, the second outlet-side flow channel 33 includes a lower flow channel portion 34 disposed below the first outlet-side flow channel 32, an upper flow channel portion 35 disposed above the first outlet-side flow channel 32, and a connecting flow channel portion 36 disposed adjacent to the first outlet-side flow channel 32 in a depth direction and connecting the lower flow channel portion 34 to the upper flow channel portion 35. The radiator-side outlet port 33a opens into the upper flow channel portion 35.

[0031] As in Fig.2, the lower flow channel portion 34 of the second output-side flow channel 33 is connected to the input-side flow channel 31 through a first bore 37 formed in the housing 30. A plurality of (three in the present embodiment) first bores 37 are spaced apart in the lateral direction. Further, the lower flow channel portion 34 of the second output-side flow channel 33 is connected to the first output-side flow channel 32 through a second bore 38 formed in the housing 30. A plurality of (three in the present embodiment) second bores 38 are spaced apart in the lateral direction so as to be located above the first bores 37, respectively. Axial centerlines of the first bore 37 and the second bore 38, which are located in the vertical direction, are coaxial.The first hole 37 and the second hole 38 are used for mounting the valves 20A and 20B, which are described later. < Valve >

[0032] Each of the valves 20A and 20B is a thermostat that operates according to the temperature of the cooling water. When the temperature of the cooling water is lower than a predetermined temperature, the valves 20A and 20B establish communication between the inlet-side flow channel 31 and the first outlet-side flow channel 32, allowing the cooling water to flow through the first bypass flow channel 16 and the second bypass flow channel 17. Furthermore, when the temperature of the cooling water is equal to or higher than the predetermined temperature, the valves 20A and 20B each establish communication between the inlet-side flow channel 31 and the second outlet-side flow channel 33, allowing the cooling water to flow through the radiator connection flow channel 15.

[0033] Specifically, the valves 20A and 20B are each disposed in the housing 30 at a position corresponding to the first bore 37 and the second bore 38 arranged in the vertical direction. The valves 20A and 20B each include a valve body 21 formed in a cylindrical shape extending in the vertical direction, a flange 22 having an annular shape projecting radially from the valve body 21, and an actuator 23 for driving the valve body 21 in the vertical direction.

[0034] The valve body 21 has a through-bore 21a extending in the vertical direction. The valve body 21 is inserted into the second bore 38 and is arranged such that an opening on a lower side of the valve body 21 faces the first bore 37. The valve body 21 is movable in the vertical direction.

[0035] The flange 22 is attached to the housing 30 on a lower side of the valve body S21. The flange 22 is arranged to surround the first bore S37 on an inner surface side of the lower flow channel region 34 into which the first bore 37 opens.

[0036] When the temperature of the cooling water is lower than the predetermined temperature, the actuator 23 moves the valve bodies 21 of the valves 20A and 20B downwards, as shown in Fig.2 to 4, so that a lower end of the valve body 21 is brought into contact with the flange 22. In this state, a gap is formed between an upper end of the valve body S21 and an upper surface 32c of the first outlet-side flow passage 32, and the inlet-side flow passage 31 communicates with the first outlet-side flow passage 32 via the first bore 37 and the through-hole 21a of the valve body S21. Further, since the lower end of the valve body S21 is in contact with the flange 22, the inlet-side flow passage 31 does not communicate with the second outlet-side flow passage 33. In the following description, this state is referred to as a state in which the second valves 20A and 20B are closed.

[0037] When the temperature of the cooling water is equal to or higher than the predetermined temperature, the actuator 23 moves the valve bodies 21 of the second valves A and 20B upwards, as shown in Fig.4 to 6, so that the upper end of the valve body 21 is brought into contact with the upper surface 32c of the first outlet-side flow channel 22. In this state, a gap is formed between the lower end of the valve body 21 and the flange 22, and the inlet-side flow channel 31 communicates with the lower flow channel portion 34 of the second outlet-side flow channel 33 via the first bore 37. Furthermore, since the upper end of the valve body 21 of the valves 20A and 20B is in contact with the upper surface 32c of the first outlet-side flow channel 32, the inlet-side flow channel 31 does not communicate with the first outlet-side flow channel 32. In the following description, this state may be referred to as a state in which the valves 20A and 20B are open.

[0038] as in Fig.2 to 6, the plurality of valves 20A and 20B include a first valve 20A that operates at a relatively low temperature and a second valve 20B that operates at a temperature higher than that of the first valve 20A and the second valve 20B.

[0039] As in Fig. 2 and Fig. 3, the first valve 20A connects the inlet-side flow channel 31 to the first outlet-side flow channel 32 when a temperature of the cooling water is lower than a first predetermined temperature (hereinafter referred to as a first temperature), and causes the cooling water to flow through the first bypass flow channel 16 and the second bypass flow channel 17. Further, as shown in Fig.4 to 6, the temperature of the cooling water is equal to or higher than the first temperature, then the first valve 20A connects the inlet-side flow channel 31 to the second outlet-side flow channel 33 and allows the cooling water to flow through the radiator connection flow channel 15. On the other hand, as shown in Fig. 2 and Fig. 4, the temperature of the cooling water is lower than a second predetermined temperature (hereinafter referred to as the second temperature) which is higher than the first temperature, then the second valve 20B connects the inlet-side flow channel 31 to the first outlet-side flow channel 32, and allows the cooling water to flow through the first bypass flow channel 16 and the second bypass flow channel 17. Further, as shown in Fig.6, the temperature of the cooling water is equal to or higher than the second temperature, then the second valve 20B connects the inlet-side flow channel 31 to the second outlet-side flow channel 33 and allows the cooling water to flow through the radiator connection flow channel 15.

[0040] The number of first valves 20A is smaller than the number of second valves 20B. The specific number of first valves 20A and second valves 20B can be arbitrary. In the present embodiment, the number of first valves 20A is one, and the number of second valves 20B is two.

[0041] Furthermore, the first valve 20A and the second valves 20B are arranged laterally between the pump-side output port 32a and the oil cooler-side output port 32b such that the first valve 20A is located between the second valves 20B. That is, the second valves 20B are arranged on both sides of the first valve 20A in the lateral direction. The number of second valves 20B provided on each side of the first valve 20A may vary, but is preferably the same for each side.

[0042] In the present embodiment, the plurality of radiator-side output ports 33a formed in the casing 30 are arranged at positions where the distances from the first valve 20A to each of the radiator-side output ports 33a in the second output-side flow passage 33 are equal to each other. In the present embodiment, a single first valve 20A is arranged midway between two radiator-side output ports 33a in the lateral direction. For example, if a plurality of first valves 20A are provided, the plurality of radiator-side output ports 33a need only be arranged at positions where the distances from a valve group consisting of the plurality of first valves 20A to each of the radiator-side output ports 33a are equal. < FUNCTION AND EFFECTS >

[0043] In the engine cooling device 4 of the present embodiment, in a state where the temperature of the cooling water is lower than the first temperature, both the first valve 20A and the second valves 20B of the flow channel switching unit 7 are closed, as shown in Fig. 2 and Fig.3. That is, the valve bodies 21 of the first valve 20A and the second valves 20B are arranged on the lower side. Therefore, all the cooling water flowing from the engine 2 and the EGR cooler 3 into the inlet-side flow passage 31 of the flow passage switching unit 7 flows through the first holes 37 corresponding to the first and second valves 20A and 20B and the through holes 21a of the valve bodies 21 to the first outlet-side flow passage 32. Then, all the cooling water flows from the pump-side outlet port 32a and the oil cooler-side outlet port 32b of the first outlet-side flow passage 22 to the first bypass flow passage 16 and the second bypass flow passage 17, and then flows to the pump 5 and the oil cooler 8. Since the cooling water does not flow to the radiator connection flow passage 15, that is,, since the cooling water does not flow from the flow channel switching unit 7 to the radiator 6, the cooling water can thus be efficiently heated by the engine 2 and the LGR cooler 3 during circulating.

[0044] Thereafter, when the temperature of the cooling water becomes equal to or higher than the first temperature and lower than the second temperature, the first valve 20A opens, but the second valves 20B remain in the closed state, as shown in Fig. 4 and Fig.5. That is, the valve body 21 of the first valve 20A is positioned on the upper side, and the valve bodies 21 of the second valves 20B are positioned on the lower side. Therefore, part of the cooling water flowing into the inlet-side flow passage 31 of the flow passage switching unit 7 sequentially flows through the gap between the valve body 21 and the flange 22 of the first valve 20A into the lower signal portion 34, the connecting flow passage portion 36, and the upper flow passage portion 35 of the second outlet-side flow passage 33. Part of the cooling water flows out from the radiator-side outlet port 33a of the radiator connecting flow passage 15 and flows to the radiator 6.

[0045] The remaining cooling water flowing in the inlet-side flow channel 31 flows via the first hole 37 corresponding to the second valve 20B and through hole 21a of the valve body 21 to the first outlet-side flow channel 32, flows from the pump-side outlet port 32a and the oil cooler-side outlet port 32b to the first bypass flow channel 16 and to the second bypass flow channel 17, and finally flows to the pump 5 and the oil cooler 8. In other words, in the Fig. 4 and Fig. In the state shown in Figure 5, the cooling water flows from the flow channel switching unit 7 to the radiator 6, the pump 5 and the oil cooler 8.

[0046] Since the number of first valves 20A is smaller than the number of second valves 20B, the flow rate of the cooling water flowing from the flow channel switching unit 7 to the radiator 6 is smaller than the flow rate of the cooling water flowing through the pump 5 and the oil cooler 8. Even in the state shown in Fig. 4 and Fig. 5, it is therefore possible to efficiently increase the temperature of the cooling water through the engine 2 and the EGR cooler 3.

[0047] Thereafter, when the temperature of the cooling water becomes equal to or higher than the second temperature, both the first valve 20A and the second valves 20B are opened as shown in Fig.6. That is, the valve bodies 21 of the first valve 20A and the second valves 20B are located on the upper side. Therefore, all the cooling water flowing from the engine 2 and the EGR cooler 3 into the inlet-side flow passage 31 of the flow passage switching unit 7 flows sequentially via a gap between the plural valve bodies 21 of the first and second valves 20A and 20B, the flanges 22, to the lower flow passage portion 34, the connecting flow passage portion 36, and the upper flow passage portion 35 of the second outlet-side flow passage 33. All the cooling water flows from the radiator-side outlet port 33a of the second outlet-side flow passage 33 to the radiator connecting flow passage 15 and flows to the radiator 6. That is, the cooling water does not flow to the first bypass flow passage 16 and the second bypass flow passage 17, and also does not flow to the pump 5 and the oil cooler 8.This prevents the temperature of the cooling water from rising excessively. [Table 1] Cooling water temperature Position of the valve body 21 of the first valve 20A Position of the valve bodies 21 of the second valves 20B Presence of cooling water in the first bypass flow channel 16 in the second bypass flow channel 17 in the radiator connection flow channel 15 smaller than first temperature lower side lower side available available unavailable equal to or higher than the first temperature and lower than the second temperature upper side lower side available available available equal to or higher than second temperature upper side upper side unavailable unavailable available

[0048] Table 1 shows the function of the engine cooling device 4 in the present embodiment described above, specifically, it shows the relationship between the temperature of the cooling water, the positions of the valve bodies 21 of the first and second valves 20A and 20B according to the temperature of the cooling water, and the presence or absence of a flow of the cooling water in the radiator connecting flow passage 15, the first bypass flow passage 16, and the second bypass flow passage 17.

[0049] As described above, according to the engine cooling device 4 and the engine system 1 of the present embodiment, when the temperature of the cooling water is equal to or higher than the first temperature and lower than the second temperature, a portion of the cooling water flows from the flow channel switching unit 7 to the radiator 6. Therefore, it is possible to reduce the pressure of the cooling water. Thus, the pressure of the cooling water at the cooling water inlet CFa of the EGR cooler 3 can be reduced to protect the EGR cooler 3. In other words, it is possible to significantly improve the durability of the EGR cooler 3 in the engine cooling device 4 and the engine system 1.

[0050] According to the engine cooling device 4 and the engine system 1 of the present embodiment, the number of first valves 20A opening at the first temperature is smaller than the number of second valves 20B opening at the second temperature. Therefore, when the temperature of the cooling water is equal to or higher than the first temperature and lower than the second temperature, the flow rate of the cooling water flowing from the flow channel switching unit 7 to the radiator 6 is smaller than the flow rate of the cooling water flowing to the pump 5 and the oil cooler 8. Compared with the case where all the cooling water is supplied to the radiator 6 by opening all the valves 20A and 20B at a low temperature, the engine 2 can be warmed up quickly. That is, it is possible to suppress a prolongation of the warm-up period of the engine 2.

[0051] According to the engine cooling device 4 of the present embodiment, the first valve 20A is opened to close a part of the first outlet-side flow passage 32 when the temperature of the cooling water is equal to or higher than the first temperature and lower than the second temperature, as shown in Fig. 4 and Fig.5. However, the first valve 20A is arranged between the second valves 20B in a direction in which the pump-side output port 32a and the oil cooler-side output port 32b formed in the first output-side flow passage 32 of the housing 30 are arranged. Therefore, even if the first valve 20A blocks part of the first output-side flow passage 32, the cooling water flowing in the first output-side flow passage 32 through the valve body 21 of each of the second valves 20B can flow smoothly to both the pump-side output port 32a and the oil cooler-side output port 32b. That is, it is possible to prevent the first valve 20A from obstructing the flow of the cooling water to the pump-side outlet port 32a and the oil cooler-side outlet port 32b in the first outlet-side flow passage 32.Therefore, by opening and closing the first valve 20A, it is possible to reduce or prevent a change in the ratio (flow rate distribution ratio) between the flow rate of the cooling water flowing to the pump 5 and the flow rate of the cooling water flowing to the oil cooler 8.

[0052] Furthermore, in the engine cooling device 4 of the present embodiment, the plurality of radiator-side outlet ports 33a are arranged at positions where the distances from the first valve 20A to each of the radiator-side outlet ports 33a in the second outlet-side flow passage 33 are equal to each other. In a state in which only the first valve 20A is opened, as shown in Fig.4, it is therefore possible to prevent or reduce the flow rate of the cooling water flowing from the first valve 20A to the two radiator-side outlet ports 33a from being different in the second outlet-side flow channel 33. That is, it is possible to allow the cooling water to flow equally through the two radiator-side outlet ports 33a. < OTHER EMBODIMENTS >

[0053] Although the embodiment of the present invention is described above, the present invention is not limited thereto and can be appropriately changed without departing from the technical idea of ​​the present invention.

[0054] For example, the engine cooling device of the present invention need not include an oil cooler 8 and a second bypass flow passage 17. [Explanation of reference symbols] 1 engine system 2 Engine or combustion engine 3 EGR coolers 4 Engine cooling system 5 Pump 5a Suction connection 5b Outlet connection 6 Radiators 7 Flow channel switching unit 8 oil coolers 9 Defoaming tanks 15 Radiator connection flow channel 16 first bypass flow channel 17 second bypass flow channel 20A first valve 20B second valve 21 Valve body 21a Through hole 22 flange 23 Actuator 30 housings 31 inlet-side flow channel 32 first outlet-side flow channel 32a pump-side output connection 32b oil cooler side output connection 33 second outlet-side flow channel 33a radiator side output connection 34 lower flow channel area 35 upper flow channel area 36 Connecting flow channel area

Claims

[1] An engine cooling device (4), comprising: a pump (5) which supplies cooling water from an outlet port (5b) of the pump (5) to an engine (2) and an EGR cooler (3); a radiator (6) which cools the cooling water from the engine (2) and the EGR cooler (3), wherein an outlet (6b) for the cooling water in the radiator (6) is connected to a suction port (5a) of the pump (5); a flow channel switching unit (7) provided in the middle of a flow channel of the cooling water from the engine (2) and from the EGR cooler (3) to the radiator (6); a radiator connection flow channel (15) connecting the flow channel switching unit (7) to the radiator (6); and a first bypass flow channel (16) connecting the flow channel switching unit (7) to the suction port (5a) of the pump (5), characterized by , that the flow channel switching unit (7) comprises: a first valve (20A) that allows the cooling water to flow through the first bypass flow channel (16) when a temperature of the cooling water is lower than a first predetermined temperature, and allows the cooling water to flow through the radiator connection flow channel (15) when the temperature of the cooling water is equal to or higher than the first predetermined temperature; and a second valve (20B) that allows the cooling water to flow through the first bypass flow channel (16) when the temperature of the cooling water is lower than a second predetermined temperature that is higher than the first predetermined temperature, and allows the cooling water to flow through the radiator connection flow channel (15) when the temperature of the cooling water is equal to or higher than the second predetermined temperature, wherein the number of first valves (20A) is smaller than the number of second valves (20B), and wherein the second valves (20B) are arranged on both sides of the first valve (20a) in a lateral direction. [2] The engine cooling device (4) according to claim 1, comprising: an oil cooler (8) through which the cooling water flows from the radiator (6), the outlet for the cooling water in the oil cooler (8) being connected to the suction connection (5a) of the pump (5); and a second bypass flow channel (17) connecting the flow channel switching unit (7) to the oil cooler (8), wherein the flow channel switching unit (7) has a housing (30) which accommodates the first valve (20A) and the second valves (20B), wherein in an inner region of the housing (30) are formed: an inlet-side flow channel (31) in which the cooling water from the engine (2) and the EGR cooler (3) flows, a first outlet-side flow channel (32) with a pump-side outlet port (32a) to which the first bypass flow channel (16) is connected, and with an oil cooler-side outlet port (32b) which is arranged at a distance from the pump-side outlet port (32a) and to which the second bypass flow channel (17) is connected, and a second outlet-side flow channel (33) to which the radiator connection flow channel (15) is connected and which has a radiator-side outlet port (33a), wherein the first valve (20A) connects the inlet-side flow channel (31) to the first outlet-side flow channel (32) when the cooling water has a lower temperature than has the first predetermined temperature,and connects the inlet-side flow channel (31) to the second outlet-side flow channel (33) when the temperature of the cooling water is equal to or higher than the first temperature, wherein each of the second valves (20B) connects the inlet-side flow channel (31) to the first outlet-side flow channel (32) when the temperature of the cooling water is lower than the second predetermined temperature, and connects the inlet-side flow channel (31) to the second outlet-side flow channel (33) when the temperature of the cooling water is equal to or higher than the second predetermined temperature, and wherein the first valve (20A) and the second valves (20B) are arranged in the direction in which the pump-side output port (32a) and the oil cooler-side output port (32b) are arranged between the pump-side output port (32a) and the oil cooler-side output port (32b), so that the first valve (20A) is arranged between the second valves (20B). [3] The engine cooling device (4) according to claim 2, wherein the second outlet-side flow channel (33) has a plurality of the radiator-side outlet connections (33a), and wherein the plurality of radiator-side output ports (33a) are arranged at positions where a distance from the first valve (20A) to each of the radiator-side output ports (33a) in the second output-side flow channel (33) is the same. [4] A motor system (1), with: an engine (2); an EGR cooler (3); and an engine cooling device (4) according to one of claims 1 to 3.

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