Cooling structure for internal combustion engine

Abstract

To provide a cooling structure of an internal combustion engine which prevents a passage component connecting a thermo housing with a radiator from being falling out from an inlet portion without changing the output of a pump device.SOLUTION: A cooling structure of an internal combustion engine (ENG) includes: a cooling passage in which a refrigerant circulating through the internal combustion engine flows; a radiator (RAD) which is disposed on the cooling passage and cools the refrigerant; and a thermo housing 3 disposed at the internal combustion engine side relative to the radiator on the cooling passage and having a built-in thermostat 3D for adjusting a flow rate of the refrigerant according to a temperature of the refrigerant. The thermo housing 3 has: a first housing passage 3A in which the refrigerant flows from the internal combustion engine to the radiator; and a passage attachment part 10 which is inserted into the passage component forming a part of the cooling passage 20 and fastened. The passage attachment part 10 has an orifice 10a which is provided protruding at the inner side so as to narrow an inner diameter of the passage attachment part 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a structure for cooling an internal combustion engine mounted on a vehicle. [Background technology]

[0002] Generally, a water-cooled internal combustion engine (hereinafter referred to as "engine") is provided with a passage through which a cooling medium (hereinafter also referred to as "cooling water") circulates, a pumping device for circulating the cooling water, a radiator for cooling the cooling water, and a passage that bypasses the radiator. This bypass passage is provided with a thermostat that opens and closes the passage depending on the temperature of the cooling water, and the flow path of the cooling water is switched by the thermostat (e.g., Patent Documents 1 and 2). For example, in the structure of Patent Document 2, the cooling water is distributed to each required part through a water outlet in which a thermostat is integrally built. Note that a thermo housing is integrally formed with this water outlet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-189421 [Patent Document 2] JP 2013-108429 A Summary of the Invention [Problem to be solved by the invention]

[0004] The thermo housing is provided with an inlet (upstream end) of the cooling water passage that connects to each required part including the radiator, and passage parts such as hoses and pipes are connected to this inlet. However, if the pressure of the cooling water heading to the radiator is too high, a problem may occur in which the passage parts connecting the thermo housing and the radiator come loose from the inlet. To address this, it is conceivable to lower the pressure by reducing the output of the pressure-feeding device, but changing the output of the pressure-feeding device is not desirable from the viewpoint of parts sharing.

[0005] The cooling structure for an internal combustion engine of the present invention has been devised in consideration of such problems, and one of its objectives is to prevent the passage parts connecting the thermo housing and the radiator from coming off from the inlet without changing the output of the pumping device. However, this objective is not the only objective, and another objective of the present invention is to achieve the effects that cannot be obtained by the conventional technology, which are derived from the configurations shown in the below-mentioned embodiments. [Means for solving the problem]

[0006] (1) The cooling structure for an internal combustion engine disclosed herein is a cooling structure for an internal combustion engine, comprising: a cooling passage through which a refrigerant that has circulated through the internal combustion engine flows; a radiator that is disposed on the cooling passage and cools the refrigerant; a plurality of branch passages that are part of the cooling passage; and a thermohousing that is disposed on the cooling passage closer to the internal combustion engine than the radiator and that incorporates a thermostat that adjusts the flow rate of the refrigerant depending on the temperature of the refrigerant. The thermohousing comprises a first housing passage through which the refrigerant flows from the internal combustion engine toward the radiator, a passage attachment portion that is disposed at the downstream end of the first housing passage and that is inserted into and fastened to a passage component that constitutes a part of the cooling passage, and a plurality of branch passages that branch off from the first housing passage. It is formed like this and a plurality of branching portions as inlets of the plurality of branching passages, the passage attachment portion having an orifice protruding inwardly so as to narrow an inner diameter of the passage attachment portion, the branching portion being located on the most downstream side of the first housing passage among the plurality of branching portions; first The branch part is In the flow direction of the refrigerant Branching from the upstream side of the orifice the orifice is located at an upstream end of the passage attachment portion in the flow direction, the first branch portion is provided adjacent to the orifice, and a position of an upstream surface of the orifice and a most downstream position on an outer circumferential surface of the first branch portion are set at the same position in the flow direction. .

[0007] (2) The above First branch supplies the refrigerant to an oil cooler that cools the lubricating oil of the internal combustion engine. It is a flow path for

[0008] ( 3The thermo housing supplies the refrigerant to a throttle body of the internal combustion engine and has a second branch portion as an inlet of a second branch passage which is one of the plurality of branch passages, and the second branch portion is one of the plurality of branch portions. ,before It is preferable that the first branch portion is located upstream of the first branch portion in the flow direction. ( 4 ) It is preferable that the inner diameter of the second branch portion is smaller than the inner diameter of the first branch portion.

[0009] ( 5 The thermo housing supplies the refrigerant to a heater for air conditioning an interior of a vehicle in which the internal combustion engine is mounted, and has a third branch portion as an inlet of a third branch passage which is one of the plurality of branch passages, and the third branch portion is one of the plurality of branch portions. ,before The third branch portion is preferably located upstream of the second branch portion in the flow direction, and has an inner diameter larger than an inner diameter of the first branch portion.

[0010] ( 6 ) It is preferable that the thermo housing has a second housing passage that communicates with the first housing passage via a space and through which the refrigerant flows from the internal combustion engine to the pumping device, and a bypass passage that is provided separately from the second housing passage and through which the refrigerant flows from the internal combustion engine to the pumping device, and that the bypass passage is formed to branch off from the first housing passage and is located upstream of the first branch portion in the flow direction. Effect of the Invention

[0011] According to the disclosed cooling structure for an internal combustion engine, it is possible to prevent the passage parts connecting the thermo housing and the radiator from coming off from the inlet portion without changing the output of the pumping device. [Brief description of the drawings]

[0012] [Figure 1] 1 is an overall view for explaining a cooling structure of an internal combustion engine according to an embodiment; [Diagram 2] 2 is a schematic diagram for explaining a thermo-housing included in the cooling structure according to the embodiment; FIG. [Diagram 3] 1 is a side view showing a thermo-housing included in a cooling structure according to an embodiment; [Figure 4] 4 is a perspective view showing the thermo-housing of FIG. 3 (view taken in the direction of the arrow A in FIG. 3). [Diagram 5] 4 is a cross-sectional view of a passage connection portion of the thermo-housing of FIG. 3 (a cross-sectional view taken along the line BB in FIG. 4). [Figure 6] FIG. 4 is a cross-sectional view taken along the line CC in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] With reference to the drawings, a cooling structure for an internal combustion engine as an embodiment will be described. The embodiment described below is merely an example, and is not intended to exclude various modifications or application of techniques not clearly stated in the following embodiment. Each configuration of the present embodiment can be modified in various ways without departing from the spirit of the embodiment. In addition, the configurations can be selected as necessary, or can be combined appropriately.

[0014] [1. Overall composition] FIG. 1 is an overall view for explaining the cooling structure of an internal combustion engine 1 (ENG, hereinafter referred to as "engine 1") of this embodiment. The engine 1 is water-cooled and is mounted on a vehicle (for example, an automobile, a truck, etc.). Hereinafter, the refrigerant that cools the engine 1 will be referred to as "cooling water", but the type of refrigerant is not particularly limited. The vehicle may be an engine vehicle, or may be a hybrid vehicle equipped with a drive source other than the engine 1.

[0015] A pumping device 2 that circulates the cooling water is attached to the engine 1. The pumping device 2 is, for example, a mechanical water pump (W / P) that is operated by the power of the engine 1. In addition to the pumping device 2, the cooling structure includes a thermo-housing 3 (T / H) that distributes the cooling water flowing out of the engine 1 to various locations, a cooling passage 20 through which the cooling water that has circulated through the engine 1 flows, and a radiator 4 (RAD) that is interposed on the cooling passage 20 and cools the cooling water. The cooling water is discharged from the pumping device 2, flows through a water jacket in the cylinder head and cylinder block of the engine 1 (both not shown), and is then distributed to various locations via the thermo-housing 3 and returns to the pumping device 2 again.

[0016] In the cooling structure of this embodiment, the cooling passage 20 includes a radiator-bound passage 30 leading to the radiator 4, a bypass passage 35 bypassing the radiator 4 and leading to the pumping device 2, and three branch passages 31, 32, and 33 branched off from a first housing passage 3A described later within the thermo housing 3.

[0017] FIG. 2 is a schematic diagram of only the configuration of the thermo housing 3, which is characteristic of this cooling structure. The thermo housing 3 is disposed on the cooling passage 20 and closer to the engine 1 than the radiator 4, and incorporates a thermostat 3D that adjusts the flow rate of the cooling water according to the temperature of the cooling water. Hereinafter, the space in which the thermostat 3D is incorporated is designated by the reference symbol 3C. As shown in FIG. 2, the thermo housing 3 of this embodiment has two inlets 3e, 3f and one outlet 3g formed in a wall portion forming the space 3C. One inlet 3e is an opening through which the cooling water flows in directly (without passing through any device, etc.) through the thermo housing 3. The other inlet 3f is an opening through which at least one of the cooling water that has passed through the radiator 4 and the cooling water that has passed through an oil cooler 5 (O / C) that cools the lubricating oil of the engine 1 flows in. Note that both FIG. 1 and FIG. 2 show a state in which one inlet 3e is closed by the thermostat 3D.

[0018] The outlet 3g is an opening that communicates with the bypass passage 35 through the outlet 16 described below. When the temperature of the coolant is lower than a predetermined lower limit, the thermostat 3D closes the other inlet 3f and switches the flow path so that the coolant bypasses the radiator 4. On the other hand, when the temperature of the coolant reaches a temperature that requires cooling, the thermostat 3D closes or narrows one of the inlets 3e, switches the flow path so that the coolant flows through the radiator 4, and adjusts the flow rate.

[0019] The first branch passage 31 is a flow path for supplying cooling water to an oil cooler 5 (O / C). The second branch passage 32 is a flow path for supplying cooling water to a throttle body 6 (T / B) of the engine 1. The third branch passage 33 is a flow path for supplying cooling water to a heater 7 (HTR) for air conditioning the interior of the vehicle. In the cooling structure of this embodiment, an EGR cooler 8 (E / C) and an electric pump 9 (E / P) are provided on the third branch passage 33 that cools the heater 7.

[0020] [2.Main part configuration] Next, the configuration of the main parts of this cooling structure will be described with reference to Figures 2 to 6. Figure 3 is a side view of the thermo-housing 3, and Figure 4 is a perspective view seen from the direction of the outlined arrow A in Figure 3. Figures 5 and 6 are cross-sectional views taken along the line BB in Figure 4 and the line CC in Figure 3, respectively.

[0021] The thermo housing 3 of this embodiment is fixed to the engine 1 by fastening the flange surface 23 to a side surface of the cylinder head or cylinder block of the engine 1. As shown in FIG. 3, the flange surface 23 is provided with an opening 15 (hereinafter referred to as the "inlet 15") through which the cooling water flows into the thermo housing 3. The thermo housing 3 is also provided with an opening 16 (hereinafter referred to as the "outlet 16") through which the cooling water is discharged from the thermo housing 3. The outlet 16 is connected to a bypass passage 35, and the cooling water flowing out from here flows toward the pressure-feeding device 2. The thermo housing 3 of this embodiment is further provided with an inlet section 17 through which the cooling water flows in after flowing through the heater 7, and a second inlet 18 (see FIG. 4) through which the cooling water flows in after flowing through the radiator 4.

[0022] As shown in Fig. 2, the thermo housing 3 has a first housing passage 3A through which cooling water flows from the engine 1 toward the radiator 4, and a passage attachment portion 10 into which a radiator hose 30a (a passage part indicated by a two-dot chain line in Fig. 5) is inserted and fastened. The radiator hose 30a is a pipe that constitutes a radiator-bound passage 30, which is a part of the cooling passage 20. On the other hand, the passage attachment portion 10 is a cylindrical portion formed in the thermo housing 3, and has a step portion 10b against which the tip of the radiator hose 30a abuts.

[0023] The passage mounting part 10 is inserted inside the tip of the radiator hose 30a, and the radiator hose 30a is clamped from the outside, so that the inner peripheral surface of the radiator hose 30a and the outer peripheral surface of the passage mounting part 10 are fixed in a state of intimate contact with each other. In this cooling structure, the pressure (flow rate) of the cooling water flowing toward the radiator 4 is reduced without changing the output of the pressure-feeding device 2 from the conventional one, thereby preventing the radiator hose 30a from coming off the passage mounting part 10.

[0024] Specifically, as shown in Figures 2, 4 and 5, the passage attachment part 10 has an orifice 10a protruding inward to narrow its inner diameter. The pressure (flow rate) of the cooling water flowing through the first housing passage 3A decreases as it passes through the orifice 10a, so that the radiator hose 30a does not come off the passage attachment part 10, and the fixing between the two does not become loose. As shown in Figure 2, the inner diameter Da of the orifice 10a is smaller than the inner diameter D3 (hereinafter referred to as the "main inner diameter D3") of the first housing passage 3A, and is set to, for example, about 0.7 times the main inner diameter D3. Note that the passage attachment part 10 has a larger thickness at the orifice 10a, which also provides a reinforcing effect.

[0025] 2 to 5, the thermo housing 3 has a first branch portion 11 as an inlet of a first branch passage 31 that supplies cooling water to the oil cooler 5. The first branch portion 11 is formed to branch off from the first housing passage 3A, and is located upstream of the orifice 10a in the flow direction of the cooling water. In the following description, when simply referring to "upstream" and "downstream," the reference is the direction (flow direction) in which the cooling water that has flowed into the thermo housing 3 from the inlet 15 flows through the first housing passage 3A of the thermo housing 3.

[0026] In this cooling structure, as shown in FIG. 2, the orifice 10a is located at the upstream end of the passage attachment portion 10, and the first branch portion 11 is provided adjacent to the orifice 10a. The thickness W2 of the boss portion of the first branch portion 11 is larger than the thickness (dimension in the flow direction) W1 of the orifice 10a. In the example shown in FIG. 5, the position P1 of the upstream surface of the orifice 10a and the most downstream position P2 of the outer circumferential surface of the boss portion of the first branch portion 11 are set to the same position in the flow direction. In other words, the root portion of the orifice 10a and the root portion of the boss portion of the first branch portion 11 are connected without a thin portion. This further enhances the reinforcing effect. Note that the wall thickness of the passage attachment portion 10 is thinner than the wall thickness upstream of the first branch portion 11 in FIG. 5, but they may be the same.

[0027] As shown in Figs. 2 to 4, the thermo housing 3 has a second branch portion 12 as an inlet of a second branch passage 32 that supplies cooling water to the throttle body 6. The second branch portion 12 is formed to branch off from the first housing passage 3A, and is located upstream of the first branch portion 11. In this cooling structure, as shown in Fig. 2, the inner diameter D12 of the second branch portion 12 is smaller than the inner diameter D11 of the first branch portion 11. Due to this positional relationship and difference in inner diameter, the flow rate of cooling water heading toward the oil cooler 5 is greater than the flow rate of cooling water heading toward the throttle body 6.

[0028] As shown in Figs. 2 to 4, the thermo housing 3 has a third branch portion 13 as an inlet of a third branch passage 33 that supplies cooling water to the heater 7. The third branch portion 13 is formed to branch off from the first housing passage 3A, and is located upstream of the second branch portion 12. In this cooling structure, as shown in Fig. 2, the inner diameter D13 of the third branch portion 13 is larger than the inner diameter D11 of the first branch portion 11. Therefore, a sufficient flow rate of cooling water toward the heater 7 is ensured. Note that, as shown in Fig. 2, the inner diameters D11 to D13 of the branch portions 11 to 13 are smaller than the inner diameter of the passage mounting portion 10 (e.g., equal to the main inner diameter D3) and the inner diameter D16 of the outlet 16.

[0029] The thermo housing 3 of this cooling structure has a second housing passage 3B (indicated by a two-dot chain line in FIG. 2) that communicates with the first housing passage 3A via a space 3C and through which the cooling water flows from the engine 1 toward the pumping device 2, and a bypass passage 14 that is provided separately from the second housing passage 3B and through which the cooling water flows from the engine 1 toward the pumping device 2, bypassing the radiator 4. The second housing passage 3B is a passage between the outlet 3g and the outlet 16. In the second housing passage 3B, when one inlet 3e is closed by the thermostat 3D, the cooling water that flows in from the second inlet 18 flows through the space 3C, and when the other inlet 3f is closed by the thermostat 3D, the cooling water of the first housing passage 3A flows through the space 3C.

[0030] As shown in FIG. 2, FIG. 3, and FIG. 6, the bypass passage 14 is a passage that returns the cooling water that has flowed into the thermo-housing 3 to the pressure-feeding device 2 by bypassing the radiator 4. The bypass passage 14 is formed so as to branch off from the first housing passage 3A, and is located upstream of the first branching portion 11. The bypass passage 14 has both a function of reducing the flow rate of the cooling water flowing to the radiator 4 by flowing a part of the cooling water toward the radiator 4 to the bypass passage 35 regardless of the open / close state of the thermostat 3D, and a function of reducing the burden on the pressure-feeding device 2 and suppressing a decrease in the total flow rate of the cooling water by releasing a part of the water pressure of the first housing passage 3A that has increased by the orifice 10a. In this embodiment, the bypass passage 14 is provided so as to directly connect the first housing passage 3A and the second housing passage 3B, and is formed so as to flow a part of the cooling water toward the radiator 4 to the bypass passage 35 without passing through the space 3C.

[0031] The flow of the cooling water will be briefly explained with reference to Figures 1 and 2. First, the cooling water flowing out of the engine 1 flows into the thermo housing 3 from the inlet 15. If one inlet 3e is closed by the thermostat 3D, the cooling water flows through the first housing passage 3A and circulates through the radiator 4 via the radiator hose 30a (radiator-bound passage 30) fixed to the passage mounting portion 10. After passing through the radiator 4, the cooling water flows in from the other inlet 3f of the thermostat 3D, passes through the outlet 3g, flows from the outlet 16 to the bypass passage 35, and returns to the pressure-feeding device 2.

[0032] Furthermore, the cooling water flowing through the first housing passage 3A branches into a first branch passage 31, a second branch passage 32, and a third branch passage 33 inside the thermo housing 3, and flows toward the oil cooler 5, the throttle body 6, and the heater 7, respectively. The cooling water that has passed through the oil cooler 5 merges with the cooling water that has passed through the radiator 4 and flows into the other inlet 3f of the thermostat 3D. The cooling water that has passed through the throttle body 6 bypasses the thermostat 3D and flows into the bypass passage 35. The cooling water flowing through the third branch passage 33 first flows into the EGR cooler 8, then flows through the electric pump 9 and the heater 7, and returns to the thermo housing 3.

[0033] [3. Actions and Effects] (1) According to the above-described cooling structure, the orifice 10a is provided in the passage attachment portion 10 where the cooling water flowing out of the engine 1 flows into the thermo-housing 3 and on its way to the radiator 4, so that the pressure (flow rate) of the cooling water flowing to the radiator 4 can be reduced. In other words, the pressure (flow rate) of the cooling water flowing to the radiator 4 can be reduced without changing the output of the pressure-feeding device 2. This makes it possible to avoid problems such as the radiator hose 30a coming off or loosening from the thermo-housing 3. Furthermore, since the wall surface of the orifice 10a is thick, the passage attachment portion 10 can also be reinforced. Therefore, when the radiator hose 30a is clamped and attached to the passage attachment portion 10, it can be clamped tightly, which also makes it possible to prevent the radiator hose 30a from coming off or coming loose.

[0034] (2) In the above cooling structure, the thermo housing 3 is provided with a first branch portion 11 connected to the oil cooler 5, and the first branch portion 11 is located upstream of the orifice 10a. This increases the inflow resistance of the cooling water downstream of the orifice 10a, and therefore increases the amount of cooling water flowing from the first branch portion 11 located upstream of the orifice 10a to the oil cooler 5. This makes it possible to avoid a situation in which the cooling capacity is insufficient, even if a smaller-diameter oil cooler 5 is installed by reusing parts. In other words, parts can be easily reused without reducing the cooling capacity.

[0035] (3) In the above-described thermo housing 3, the orifice 10a is located at the upstream end of the passage mounting portion 10, and the first branch portion 11 is provided adjacent to the orifice 10a, which further enhances the reinforcing effect of the passage mounting portion 10. Furthermore, since the branch portion 11 to the oil cooler 5 is located immediately upstream of the orifice 10a, the cooling water flows more easily toward the oil cooler 5.

[0036] (4) In the above cooling structure, the thermo housing 3 is provided with the second branch 12 connected to the throttle body 6, and the second branch 12 is disposed upstream of the first branch 11. By flowing cooling water through the throttle body 6, it is possible to prevent the throttle valve from freezing in cold regions, but the amount of cooling water required at this time is not so large, and conversely, if too much cooling water is flowed, there may be a shortage of cooling water for other passages. Therefore, in the above cooling structure, the first branch 11 connected to the oil cooler 5 is provided upstream of the orifice 10a, and the second branch 12 connected to the throttle body 6 is provided further upstream of the first branch 11. The first branch 11 is greatly influenced by the orifice 10a, making it easier for the cooling water to flow to the oil cooler 5, while the second branch 12 is less influenced by the orifice 10a, making it difficult for the cooling water to flow to the throttle body 6. This makes it possible to supply an appropriate amount of cooling water to the places where cooling water is required.

[0037] (5) In particular, in the above-mentioned thermo housing 3, the inner diameter D12 of the second branch portion 12 is smaller than the inner diameter D11 of the first branch portion 11, so that the flow rate of the cooling water to the throttle body 6 can be narrowed, and as a result, the cooling water can more easily flow to other branch passages such as the first branch portion 11.

[0038] (6) In the above cooling structure, the thermo housing 3 is provided with the third branch portion 13 connected to the heater 7, and the third branch portion 13 is located upstream of the second branch portion 12, and the inner diameter D13 of the third branch portion 13 is larger than the inner diameter D11 of the first branch portion 11. Since the heater 7 requires a large amount of cooling water, it is preferable that the inner diameter D13 of the third branch portion 13 (third branch passage 33) is large, but if the inner diameter D13 is large, it becomes difficult for the cooling water to flow to the oil cooler 5 and the throttle body 6. Therefore, by arranging the third branch portion 13 at a position farther away from the orifice 10a than the first branch portion 11 and the second branch portion 12, it is possible to reduce the influence of the orifice 10a, and the cooling water can be appropriately supplied to each location.

[0039] (7) In the above cooling structure, the thermo-housing 3 is provided with a bypass passage 14, which is separate from the second housing passage 3B and through which the cooling water flows from the engine 1 to the pumping device 2, bypassing the radiator 4, and the bypass passage 14 is located upstream of the first branching portion 11. Therefore, even when the second housing passage 3B is in a closed state, a part of the cooling water can be made to flow to the detour passage 35 through the bypass passage 14, so that the flow rate of the cooling water toward the radiator 4 can be reduced. In addition, the orifice 10a releases a part of the increased water pressure of the first housing passage 3A, so that the load on the pumping device 2 can be reduced and a decrease in the total flow rate of the cooling water can be suppressed. Even if the bypass passage 14 is provided, the orifice 10a can ensure a sufficient flow rate of the cooling water to the oil cooler 5.

[0040] [4.Other] The above-mentioned cooling structure is an example, and is not limited to the above. For example, instead of the above-mentioned bypass passage 14, a bypass passage for circulating the cooling water between the pumping device 2 and the thermo-housing 3 (i.e., not passing through the engine 1) may be provided. When a bypass passage is provided, it is sufficient that the bypass passage is formed so that the cooling water flows from the engine 1 to the pumping device 2, bypassing the radiator 4, and is located upstream of the first branch portion 11.

[0041] Furthermore, when cooling water other than the cooling water for the engine 1 is used to cool the heater 7, the above-mentioned third branch portion 13 (third branch passage 33) is not necessary. Furthermore, when a separate device for preventing the throttle valve from freezing is provided or when there is no need to flow cooling water through the throttle body 6, the above-mentioned second branch portion 12 (second branch passage 32) is not necessary. Conversely, a branch portion other than the above-mentioned branch portions may be provided in the thermo housing 3.

[0042] When the first branched portion 11 (first branch passage 31) is provided, its position is not limited to the above-mentioned position. In Fig. 5, the position P1 on the upstream surface of the orifice 10a and the most downstream position P2 on the outer circumferential surface of the boss portion of the first branched portion 11 are set at the same position in the flow direction, but these positions P1 and P2 may be separated from each other in the flow direction, or the orifice 10a and the boss portion may overlap. In the latter case, the reinforcing effect can be further enhanced.

[0043] In addition, when the above-mentioned three branched portions 11 to 13 are provided, the size relationship of the inner diameters D11 to D13 of the respective portions may be set to be different from that described above. Also, the inner diameter Da and the thickness W1 of the orifice 10a are merely examples and are not limited to those described above. Furthermore, the cooling passages shown in FIG. 1 are just an example, and the manner in which the passages are connected is not limited to that described above. [Explanation of symbols]

[0044] 1. Engine (internal combustion engine) 2. Pressure feed device 3 Thermo housing 3A First housing passage 3B Second housing passage 3C space 3D Thermostat 4. Radiator 5 Oil cooler 6. Throttle body 7 Heater 10 Passage attachment part 10a Orifice 11 First branch 12 Second branch 13 Third branch 14 Bypass Passage 20 Cooling passage 30 Passage to radiator 30a Radiator hose (passage part) 31 First Branch Passage 32 Second Branch Passage 33 Third Branch Passage

Claims

1. A cooling structure for an internal combustion engine, a cooling passage through which a coolant that has circulated through the internal combustion engine flows; a radiator disposed on the cooling passage and configured to cool the refrigerant; a plurality of branch passages that are part of the cooling passage; a thermohousing that is disposed on the cooling passage and closer to the internal combustion engine than the radiator, and that has a built-in thermostat that adjusts the flow rate of the refrigerant in accordance with a temperature of the refrigerant; the thermo-housing includes a first housing passage through which the refrigerant flows from the internal combustion engine toward the radiator, a passage attachment portion that is provided at a downstream end of the first housing passage and is inserted into and fastened to a passage component that constitutes a part of the cooling passage, and a plurality of branch portions that are formed to branch off from the first housing passage and serve as inlets of the plurality of branch passages, The passage mounting portion has an orifice protruding inwardly so as to narrow an inner diameter of the passage mounting portion, a first branch portion located at the most downstream side of the first housing passage among the plurality of branch portions is branched from an upstream side of the orifice in a flow direction of the refrigerant, the orifice is located at an upstream end of the passage attachment portion in the flow direction, The first branch portion is provided adjacent to the orifice, and a position of an upstream surface of the orifice and a most downstream position on an outer circumferential surface of the first branch portion are set at the same position in the flow direction. A cooling structure for an internal combustion engine, comprising:

2. The first branch portion is a flow path for supplying the refrigerant to an oil cooler that cools lubricating oil of the internal combustion engine.

2. The cooling structure for an internal combustion engine according to claim 1.

3. the thermo housing supplies the refrigerant to a throttle body of the internal combustion engine and has a second branch portion serving as an inlet of a second branch passage which is one of the plurality of branch passages, The second branch portion is one of the plurality of branch portions and is located upstream of the first branch portion in the flow direction.

3. The cooling structure for an internal combustion engine according to claim 2.

4. The inner diameter of the second branch portion is smaller than the inner diameter of the first branch portion.

4. The cooling structure for an internal combustion engine according to claim 3.

5. the thermo housing supplies the refrigerant to a heater for air conditioning an interior of a vehicle in which the internal combustion engine is mounted, and has a third branch portion serving as an inlet of a third branch passage which is one of the plurality of branch passages, the third branch portion is one of the plurality of branch portions and is located upstream of the second branch portion in the flow direction, The inner diameter of the third branch portion is larger than the inner diameter of the first branch portion.

5. The cooling structure for an internal combustion engine according to claim 3 or 4.

6. the thermo housing has a second housing passage that communicates with the first housing passage via a space and through which the refrigerant flows from the internal combustion engine to the pressure-feeding device, and a bypass passage that is provided separately from the second housing passage and through which the refrigerant flows from the internal combustion engine to the pressure-feeding device, bypassing the radiator, The bypass passage is formed to branch off from the first housing passage and is located upstream of the first branch portion in the flow direction. The cooling structure for an internal combustion engine according to any one of claims 2 to 5.

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