Gas-liquid separation mechanism of reserve tank

Abstract

To provide a gas-liquid separation mechanism of a reserve tank capable of efficiently and surely separating bubbles contained in a coolant by a simple structure.SOLUTION: A reserve tank 10 includes: a coolant inlet opening 14 provided in a lower part of one of opposed side walls; an outlet opening 15 provided in a lower part of the other of the side walls; a bubble discharge port 17 formed in an upper wall 13D for discharging bubbles separated from the coolant; and a partition wall 16 extending in parallel with a direction from the inlet opening 14 side to the outlet opening 15 side and partitioning the reserve tank into a first chamber 18 and a second chamber 19, in which the first chamber 18 is provided with the inlet opening 14 and the outlet opening 15, the bubble discharge port 17 is provided at least in the first chamber 18, and the partition wall 16 includes: a downstream side communication hole 16a provided at a lower position of an end portion on the outlet opening 15 side of the reserve tank 10; and an upstream side communication hole 16b provided at an upper position of an end portion on the inlet opening 14 side of the reserve tank 10.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a gas-liquid separation mechanism for a reserve tank provided in a circulation path of a coolant. [Background technology]

[0002] For example, a vehicle is provided with a cooling system that cools heat-generating equipment such as an engine and a power conversion device by circulating a coolant. In this cooling system, the heat-generating equipment is cooled by circulating the coolant through a circulation path that forms a closed loop. The coolant, which has been used to cool the heat-generating equipment and has become hot, is cooled by heat exchange with outside air in a heat exchanger such as a radiator, for example, and the coolant, whose temperature has been reduced by this cooling, is used again to cool the heat-generating equipment. By continuously repeating this action, the heat-generating equipment is cooled and its temperature is kept below a certain value.

[0003] Incidentally, a reserve tank for storing the coolant is provided upstream of the liquid pump in the circulation path of the coolant. This reserve tank replenishes the coolant in the cooling circuit and absorbs volume changes caused by thermal expansion of the coolant. This reserve tank is provided with a gas-liquid separation mechanism for separating and removing air bubbles contained in the coolant. By separating and removing air bubbles contained in the coolant by the gas-liquid separation mechanism before the coolant is sucked into the liquid pump, the liquid pump is prevented from sucking in air bubbles, and malfunctions of the liquid pump caused by the sucking in of air bubbles are prevented.

[0004] As a reserve tank equipped with a gas-liquid separation mechanism, for example, Patent Document 1 proposes a reserve tank having a gas-liquid separation structure in which a plurality of partitions perpendicular to the flow of the coolant are provided inside the reserve tank, and each partition has a through hole formed therein. This reserve tank is provided with rectangular wing pieces bent into an arc shape as a vortex generation suppression means on the rear side, as viewed in the flow direction of the coolant, adjacent to the through holes of each partition, to prevent the generation of vortexes in the flow of the coolant after passing through the through holes. Here, the wing pieces are the same height as the partitions, and are provided on both sides of the through holes in a shape that gradually widens so as to sandwich the through holes. According to this reserve tank, the generation of vortexes on the rear surface of the partitions where the through holes are formed in the tank can be suppressed, thereby improving the gas-liquid separation effect.

[0005] Patent Document 2 also proposes a reserve tank in which a tank main body has a plurality of internal partition walls that are configured perpendicular to the flow direction of the coolant, and a first tank outlet and a second tank outlet are provided. The second tank outlet of this reserve tank is arranged so that the path length of the second flow path is shorter than the path length of the first flow path passing through the plurality of internal partition walls. This reduces the amount of coolant flowing through the first flow path, which has a longer path length, and accordingly reduces rippling of the liquid surface in the tank main body. As a result, even if the circulation flow rate of the coolant increases in the cooling system, it is possible to suppress the entrainment of air into the coolant in the tank main body. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-120906 A [Patent Document 2] JP 2017-166347 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the reserve tank proposed in Patent Document 1 requires the formation of multiple bulkheads perpendicular to the flow of the coolant, as well as multiple wing pieces to guide the coolant through these bulkheads, which results in a complicated manufacturing process and a complex structure, resulting in high manufacturing costs.

[0008] Furthermore, the reserve tank proposed in Patent Document 2 requires the formation of multiple partition walls perpendicular to the flow of the coolant, which complicates the manufacturing process and the structure, resulting in high manufacturing costs.

[0009] The present invention has been made in consideration of the above problems, and its object is to provide a gas-liquid separation mechanism for a reserve tank that can efficiently separate and recover air bubbles contained in the coolant with a simple configuration. [Means for solving the problem]

[0010] In order to achieve the above object, one embodiment of the present invention provides a gas-liquid separation mechanism for separating air bubbles contained in a coolant flowing into a reserve tank provided upstream of a liquid pump in a coolant circulation path, the reserve tank comprising an inlet opening for the coolant provided in a lower portion of one of the opposing side walls, an outlet opening for the coolant provided in the lower portion of the other side wall, an air bubble discharge port formed in an upper wall for discharging air bubbles separated from the coolant, and a partition wall extending approximately parallel to a direction from the inlet opening side to the outlet opening side and dividing the reserve tank into a first chamber and a second chamber on the left and right, the inlet opening and the outlet opening being provided in the first chamber, the air bubble discharge port being provided in at least the first chamber, and the partition wall having a downstream side communication hole provided below an end portion on the outlet opening side and an upstream side communication hole provided above an end portion on the inlet opening side. Effect of the Invention

[0011] According to the present invention, there is provided a gas-liquid separation mechanism for a reserve tank that can efficiently separate and recover air bubbles contained in a coolant with a simple configuration. [Brief description of the drawings]

[0012] [Figure 1] 1 is an external front view of a reserve tank (sub-tank) equipped with a gas-liquid separation mechanism according to an embodiment of the present invention. [Figure 2A] FIG. 2 is a top view of a reserve tank (sub tank) illustrating the configuration of a gas-liquid separation mechanism according to one embodiment of the present invention. [Figure 2B] FIG. 2 is a top view of a reserve tank (sub tank) illustrating the configuration of a gas-liquid separation mechanism according to one embodiment of the present invention. [Figure 2C] FIG. 2 is a top view of a reserve tank (sub tank) illustrating the configuration of a gas-liquid separation mechanism according to one embodiment of the present invention. [Diagram 3] 1 is a front perspective view of a reserve tank (sub tank) illustrating a configuration of a gas-liquid separation mechanism according to an embodiment of the present invention. FIG. [Figure 4] 10 is a rear perspective view conceptually illustrating the flow of coolant into and out of a second chamber of a reserve tank (sub-tank) illustrating the configuration of a gas-liquid separation mechanism according to one embodiment of the present invention. FIG. [Diagram 5] 10 is a rear perspective view conceptually illustrating movement of air bubbles in a second chamber of a reserve tank (sub tank) illustrating a configuration of a gas-liquid separation mechanism according to one embodiment of the present invention. FIG. [Figure 6] FIG. 2 is a rear view of a partition wall 16 of a reserve tank (sub tank) showing a first modified example of the present invention. [Figure 7] 1 is a block diagram showing a configuration of a cooling system provided in a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] FIG. 7 shows a cooling system as an example to which the gas-liquid separation mechanism according to the embodiment of the present invention is applied, and is a block diagram showing a circulation path of the coolant taken as an example of a case where the cooling system is installed in a vehicle. In the cooling system 100 shown in the figure, the coolant circulates through a circulation path that forms a closed loop. This circulation of the coolant cools the power conversion device 130 and the oil cooler 140, which are heat-generating devices, and keeps their temperatures below a certain value. Here, the power conversion device 130 includes an inverter (INV), a DC-DC converter, an on-board charger (OBC), and the like. In addition, the coolant uses a liquid (antifreeze) whose main component is ethylene glycol, which has high thermal conductivity and is difficult to freeze.

[0015] Here, a liquid pump 110 for circulating the coolant is provided in the circulation path, and a radiator 120, a power converter 130, an oil cooler 140, and a sub-tank 10 of a reserve tank 11 are sequentially arranged along the flow direction of the coolant discharged from the liquid pump 110. A pipe 111 extending from the discharge side of the liquid pump 110 is connected to the inlet side of the radiator 120, and a pipe 112 extending from the outlet side of the radiator 120 is connected to the inlet side of the power converter 130. A pipe 113 extending from the outlet side of the power converter 130 is connected to the inlet side of the oil cooler 140, and a pipe 114 extending from the outlet side of the oil cooler 140 is connected to the inlet side of the sub-tank 10. A pipe 115 extending from the outlet side of the sub-tank 10 is connected to the suction side of the liquid pump 110. The radiator 120 is provided with an electric radiator fan 121 for passing outside air through the radiator 120 to promote heat exchange between the coolant and the outside air.

[0016] In this application example, the reserve tank 11 is divided into a main tank 12 and a sub tank 10, and the gas-liquid separation mechanism according to the present invention is provided in the sub tank 10. Here, the sub tank 10 is provided in the circulation path as described above, and the main tank 12 is disposed above the sub tank 10. The main tank 12 and the sub tank 10 are connected to each other by a communication pipe 116.

[0017] In the above application example, the power converter 130 and the oil cooler 140 are given as examples of heat generating devices to be cooled, but the objects to be cooled may be engines or other auxiliary devices.

[0018] Next, the configuration of the sub-tank 10 and the gas-liquid separation mechanism provided in the sub-tank 10 according to the embodiment of the present invention will be described in detail with reference to FIGS.

[0019] FIG. 1 shows a front view of a subtank 10 equipped with a gas-liquid separation mechanism according to one embodiment of the present invention, FIGS. 2A to 2C show a top view of a subtank 10 equipped with a gas-liquid separation mechanism according to one embodiment of the present invention, and FIG. 3 shows a front oblique view of a subtank 10 equipped with a gas-liquid separation mechanism according to one embodiment of the present invention.

[0020] The subtank 10 is formed in a substantially rectangular box shape, with a circular inlet opening 14 through which the cooling liquid flows in formed in the lower part of one side wall 13A, and a circular outlet opening 15 through which the cooling liquid flows out formed in the lower part of the opposing side wall 13B. These side walls 13A and 13B are connected by two side walls 13E and 13F that are perpendicular to them, and are further configured as a rectangular tank sealed by a bottom wall 13C and a top wall 13D.

[0021] Another characteristic feature is that a partition wall 16 is provided to roughly divide the sub-tank 10 in the direction of flow of the coolant into two. The partition wall 16 divides the sub-tank 10 into a first chamber 18 and a second chamber 19.

[0022] Incidentally, the connection portion of one nipple 14a constituting the inlet flow passage to the side wall 13A on the upstream side of the sub-tank 10 is formed as a circular inlet opening 14, and the other nipple 15a constituting the outlet flow passage opens as a circular outlet opening 15 at the lower part of the side wall 13B on the downstream side. Therefore, the inlet opening 14 and the outlet opening 15 are opened opposite to each other in the flow direction of the cooling liquid, and are each provided in the first chamber 18. Therefore, the main stream of the cooling liquid is configured to flow from the inlet opening 14 into the first chamber 18 and flow out of the first chamber 18 through the outlet opening 15. In addition, round pipe-shaped nipples 14a, 15a constituting the inlet flow passage and the outlet flow passage are horizontally connected to the inlet opening 14 and the outlet opening 15, respectively. And, pipes 114, 115 shown in FIG. 7 are connected to each nipple 14a, 15a, respectively.

[0023] Furthermore, a round pipe-shaped nipple 17a is vertically connected to the upper part of the first chamber 18 at a position near the upstream side of the widthwise center of the upper wall 13D of the subtank 10 (to the right in FIG. 3, to the left in FIG. 4) (see FIG. 2A), and one end of the communication pipe 116 shown in FIG. 7 is connected to this nipple 17a. Here, the nipple 17a opens into the upper wall 13D of the subtank 10 as a circular bubble discharge port 17 for discharging air bubbles separated from the cooling liquid. And, corresponding to this bubble discharge port 17, an upper communication hole 16d is provided at the upper end of the partition wall 16 at a position that is approximately the same distance from both side walls of the reserve tank as the installation position of the bubble discharge port 17. The installation position of nipple 17a may be the upper part of second chamber 19 as shown in FIG. 2B, or may be a position spanning first chamber 18 and second chamber 19 as shown in FIG. 2C, or may be provided at the upper part of first chamber 18 and at the upper part of second chamber 19, respectively.

[0024] In the sub-tank 10 configured as above, the partition 16 described above, and the downstream communication hole 16a, the upstream communication holes 16b, 16c, and the upper communication hole 16d provided in the partition 16 constitute the gas-liquid separation mechanism according to the present invention. Although the configuration of the main tank 12 is not shown in the figures and is not described in detail, the upper end of the main tank 12 has an opening for refilling the cooling liquid, and this opening is closed by a cap. The cap is provided with a valve (relief valve), and air bubbles BB separated from the cooling liquid by the gas-liquid separation mechanism provided in the sub-tank 10 as described later are introduced into the main tank 12 through the communication pipe 116 by buoyancy. When the internal pressure of the main tank 12 exceeds a predetermined value, the valve opens and the air in the main tank 12 is discharged into the atmosphere.

[0025] Next, the operation of the gas-liquid separation mechanism according to the present invention will be described below with reference to FIGS.

[0026] 3 is a front perspective view of the subtank 10 showing the operation of the gas-liquid separation mechanism according to the present invention. As described above, the cooling liquid used to cool the power converter 130 and the oil cooler 140, which are heat generating devices, flows horizontally into the first chamber 18 as the main flow MF from the inlet opening 14 of the upstream nipple 14a to the lower part of the subtank 10, as shown in FIG. 3. Then, part of the main flow MF of the cooling liquid that flows horizontally into the lower part of the first chamber 18 is guided by the downstream communication hole 16a to the second chamber 19 corresponding to the back side of the partition wall 16 as it flows toward the downstream outlet opening 15. The remaining majority of the cooling liquid flows from the outlet opening 15 through the downstream nipple 15a and the piping 115 shown in FIG. 7 to be sucked into the suction side of the liquid pump 110.

[0027] Here, the first chamber 18 is configured to have a volume equal to or more than half that of the subtank 10, and a large space is provided above the inlet opening 14 of the upstream nipple 14a and the outlet opening 15 of the downstream nipple 15a. Therefore, there is enough time and space to effectively separate relatively large bubbles from the mainstream MF while ensuring a sufficient flow rate of the mainstream MF of the cooling liquid flowing into the first chamber until the mainstream MF flows out to the outlet opening 15, and the bubbles in the first chamber remain above the first chamber 18 for a short period of time. Then, some of the bubbles flow due to buoyancy from the bubble discharge port 17 through the nipple 17a and the connecting pipe 116 shown in FIG. 7 into the main tank 12 shown in FIG. 7 and are collected.

[0028] FIG. 4 is a rear perspective view showing the operation of the gas-liquid separation mechanism according to the present invention, and conceptually showing the flow of cooling liquid in and out of the second chamber. The second chamber 19 is shown in the foreground of FIG. 4. The second chamber 19 is configured to have a volume less than half that of the sub-tank 10, and therefore has a smaller volume than the first chamber 8. As described above, a portion of the cooling liquid flowing into the first chamber 18 as the main flow MF is introduced into the second chamber 19 through the downstream communication hole 16a of the partition wall 16. The sub-flow of the cooling liquid introduced into the second chamber 19 from the downstream communication hole 16a flows in from below the second chamber 19 and flows toward the upstream communication holes 16b and 16c, creating a generally upward flow in the second chamber.

[0029] FIG. 5 is a rear perspective view showing the operation of the gas-liquid separation mechanism according to the present invention, and conceptually showing the movement of air bubbles in the second chamber. The upward flow of the sub-current of the cooling liquid introduced from the downstream communication hole 16a into the second chamber 19 acts to raise the relatively small air bubbles bb contained in the cooling liquid. In addition, this upward flow collides with the side walls 13A, 13B, the upper wall 13D, and the bottom wall 13C of the sub-tank 10, generating a vertically rotating vortex of the cooling liquid. Due to the action of this vertically rotating vortex, the relatively small air bubbles bb contained in the cooling liquid are retained in the upper part of the second chamber. In addition, according to this configuration, the sub-current of the cooling liquid that flows into the lower part of the second chamber 19 is divided into two and flows toward the upper and lower upstream communication holes 16b, 16c. The upper upstream communication hole 16b has the function of guiding the sub-current of the cooling liquid from the downstream communication hole 16a upward, while the lower upstream communication hole 16c has the function of allowing only the cooling liquid to flow into the first chamber 18 without allowing the air bubbles bb to flow out again into the first chamber 18. Here, the total area of ​​the upper and lower upstream communication holes 16b, 16c is larger than the downstream communication hole 16a, and since the product of the hole area and the flow rate is constant, the larger the communication hole area is, the slower the flow rate will be, and therefore the speed of the flow toward the upstream communication hole will be slower. This action further promotes separation of the air bubbles bb contained in the cooling liquid (sub-current) that has flowed into the subtank 10 from the cooling liquid.

[0030] Furthermore, with the above configuration, the flow rate of the cooling liquid flowing out (returning) from the second chamber 19 to the first chamber 18 via the upstream communication holes 16b and 16c is relatively slower than the flow rate of the sub-current of the cooling liquid introduced from the downstream communication hole 16a. This prevents air bubbles bb in the second chamber 19 from being drawn back into the first chamber 18 and flowing out of the sub-tank 10.

[0031] Furthermore, an upper communication hole 16d is provided slightly upstream of the part of the partition wall 16 that contacts the upper wall 13D of the sub-tank 10. Air bubbles that rise in the first chamber 18 and the second chamber 19 and remain near the upper wall are allowed to move through this upper communication hole 16d to the other chamber space. In particular, since the speed of the sub-current is reduced by the upper upstream communication hole 16b, the speed of the flow of the air bubbles bb passing through the upper communication hole 16d can be sufficiently slowed. Therefore, even if the air bubble discharge port 17 is provided only in the first chamber 18, the air bubbles bb that have accumulated in the second chamber 19 move to the first chamber 18 through this upper communication hole 16d. The air bubbles BB in the first and second chambers are efficiently discharged from the air bubble discharge port 17 by buoyancy, and flow into the main tank 12 shown in FIG. 7 through the nipple 17a and the communication pipe 116 shown in FIG. 7 to be collected. When the bubble discharge port 17 is formed on the first chamber 18 side and the upper communication hole 16d is not formed, the bubbles bb remaining above the second chamber move from the upstream communication hole 16b to the first chamber side over time and are discharged from the bubble discharge port 17. If the bubble discharge port 17 is formed to span the upper parts of the first and second chambers, it is possible to discharge the bubbles from the bubble discharge port 17 even if the upper communication hole 16d is omitted (see FIG. 2C). Alternatively, when an additional bubble discharge port is formed on the second chamber side, the bubbles bb are also discharged from above the second chamber. Note that, as a result of the bubbles BB being collected in the main tank 12, when the internal pressure of the main tank 12 exceeds a predetermined value, as described above, a valve (relief valve) provided on a cap (not shown) of the main tank 12 opens, and air is discharged into the atmosphere.

[0032] By repeating the above actions, separation of air bubbles contained in the coolant that has flowed into subtank 10 as the mainstream MF from the coolant is promoted, and air bubbles BB separated from the coolant are collected by main tank 12. As a result, air bubbles are prevented from being contained in the coolant that flows out of subtank 10 into piping 115 shown in Fig. 7 and is sucked into liquid pump 110. This reliably prevents malfunctions caused by air intake by liquid pump 110, and ensures stable operation of liquid pump 110.

[0033] The gas-liquid separation mechanism for separating the gas bubbles contained in the cooling liquid from the cooling liquid as described above is constructed by a simple structure of providing the gas bubble outlet 17 on the upper wall 13D of the subtank 10, and providing a partition wall 16 having a downstream communication hole 16a, two upstream communication holes 16b and 16c, and an upper communication hole 16d, approximately parallel to the flow direction of the main stream MF of the cooling liquid. This simplifies the structure of the gas-liquid separation mechanism, and also simplifies the structure of the subtank 10 having the gas-liquid separation mechanism, thereby keeping the manufacturing cost low. It goes without saying that the shape of each communication hole is not limited to the shape shown in the figure, and various shapes can be adopted.

[0034] 7 according to this embodiment, the reserve tank 11 is divided into the main tank 12 and the sub tank 10, and a gas-liquid separation mechanism is provided in the sub tank 10, which simplifies and downsizes the structure of the main tank 12. At the same time, the sub tank 10 can be filled with the cooling liquid, which reliably solves the problem of air being sucked into the liquid pump 110.

[0035] Next, a modified example of the present invention will be described.

[0036] (Variation 1) In the above embodiment, the upstream communication holes are provided at two locations, one at the top and one at the bottom. However, as shown in FIG. 6, the area of ​​the upper upstream communication hole 16b may be made larger than the area of ​​the downstream communication hole 16a, and the lower upstream communication hole 16c may be omitted.

[0037] By forming the upper upstream communication hole 16b as described above, the flow direction of the sub-current of the cooling liquid flowing from the downstream communication hole 16a to the second chamber can be guided upward. By forming the area of ​​the upper upstream communication hole 16b larger than the area of ​​the downstream communication hole 16a, the flow speed of the sub-current flowing from the second chamber 19 to the first chamber 18 (returning to the first chamber) via the upstream communication hole 16b can be made slower than the flow speed of the sub-current of the cooling liquid introduced from the downstream communication hole 16a. As described above, the product of the area of ​​the hole and the flow speed is constant, so the larger the hole, the slower the sub-current speed becomes. This prevents the air bubbles bb in the second chamber 19 from being drawn back to the first chamber 18 and flowing out of the sub-tank 10. By adopting such a configuration, the configuration of the sub-tank 10 becomes simpler and the manufacturing becomes easier.

[0038] (Variation 2) In the above embodiment, the first chamber 18 is configured to have a volume equal to or greater than half that of the subtank 10, and the second chamber 19 is configured to have a volume less than half that of the subtank 10, but the volumes of the first chamber 18 and the second chamber 19 may be configured to be approximately equal.

[0039] As described above, by configuring the first chamber 18 and the second chamber 19 to have substantially the same volume, the structure of the sub-tank 10 becomes simpler and the manufacture becomes easier.

[0040] (Variation 3) In the above embodiment, the sub-tank 10 is formed into a substantially rectangular box shape, but the upper wall 13D of the sub-tank 10 may be formed into a gable roof shape (triangular shape).

[0041] As described above, by configuring the upper wall 13D of the subtank 10 in a gable roof shape (triangular shape), the air bubbles in the first chamber 18 and the second chamber 19 are guided upward more smoothly, making it easier to effectively discharge the air bubbles BB from the air bubble discharge port 17 (nipple 17a).

[0042] Although the above describes an embodiment in which the present invention is applied to a gas-liquid separation mechanism of a reserve tank 11 (sub-tank 10) provided in a vehicle cooling system 100, the present invention can also be applied to a gas-liquid separation mechanism of a reserve tank provided in any cooling system other than a vehicle.

[0043] In the embodiment described above, an example has been described in which the reserve tank 11 is divided into two, the main tank 12 and the sub-tank 10, and a gas-liquid separation mechanism is provided in the sub-tank 10. However, it goes without saying that the present invention can also be applied to a gas-liquid separation mechanism provided in a stand-alone reserve tank.

[0044] In addition, the present invention is not limited to the application of the embodiments described above, and various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0045] 10 Subtank 11 Reserve Tank 12 Main Tank 13A Upstream side wall of sub-tank 13B Downstream side wall of sub-tank 14 Entrance opening 14a Nipple (inlet passage) 15 Exit opening 15a Nipple (outlet passage) 16 Bulkhead 16a Downstream communication hole 16b Upstream communication hole (upper) 16c Upstream communication hole (lower) 16d Upper communication hole 17 Air bubble outlet 17a nipple 18 Room 1 19 Room 2 100 Cooling System 110 Liquid Pump 116 Communication pipe 120 Radiator 130 Power conversion device 140 Oil cooler BB, bb bubble MF Mainstream Coolants

Claims

1. In a gas-liquid separation mechanism for separating bubbles contained in a coolant flowing into a reserve tank provided upstream of a liquid pump in a coolant circulation path, the reserve tank includes: an inlet opening of the coolant provided at a lower portion of one of the opposing side walls; an outlet opening of the coolant provided at a lower portion of the other side wall; a bubble discharge port formed in an upper wall for discharging bubbles separated from the coolant; a partition wall extending substantially parallel to a direction from the inlet opening side toward the outlet opening side and partitioning the reserve tank into a left and a right first chamber and second chamber; and the inlet opening and the outlet opening are provided in the first chamber, the bubble discharge port is provided in at least the first chamber, and the partition wall has: a downstream communication hole provided at a position below an end portion on the outlet opening side; and an upstream communication hole provided at a position above an end portion on the inlet opening side. A gas-liquid separation mechanism for a reserve tank, characterized by the above.

2. The gas-liquid separation mechanism for a reserve tank according to claim 1, characterized in that an upper communication hole for communicating the first chamber and the second chamber is provided at a predetermined position at an upper end of the partition wall.

3. The gas-liquid separation mechanism for a reserve tank according to claim 1 or 2, characterized in that the upstream communication hole is formed larger than the downstream communication hole.

4. The gas-liquid separation mechanism for a reserve tank according to claim 1 or 2, characterized in that in addition to a position above the partition wall, the upstream communication hole is additionally provided at a position below the partition wall.

5. The gas-liquid separation mechanism for a reserve tank according to claim 1 or 2, characterized in that the first chamber is formed to have a larger volume than the second chamber.

6. The gas-liquid separation mechanism for a reserve tank according to claim 1 or 2, characterized in that the bubble discharge port is provided so as to open across both the first chamber and the second chamber.

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