JPWO2017056475A1 - Expansion tank - Google Patents

Abstract

An object of the present invention is to prevent a coolant from flowing out from a communication hole even when the flow rate of the coolant flowing into a storage chamber increases. A storage chamber 15 of a tank body 12 is divided into a plurality of chambers 24, 26, 28, 30 and lower communication portions 32, 34, 36 and an upper communication portion 62 are connected to each other in the lower and upper chambers. , 64, 66, 68 are provided with a plurality of partition walls 16, 18, 20, 22, and one of the plurality of chambers forms an inlet chamber 24 having an inlet 44 opened, and the other one chamber. Forms an outlet chamber 30 with an outlet 40 open, and the remaining chambers have intermediate chambers 26 and 28. A communication hole 52 communicates with a chamber other than the outlet chamber 30, and the communication hole 52 communicates with the chamber 26. The lower edges of the upper communication portions 62 and 66 of the partition walls 16 and 20 are located below the lower edges of the upper communication portions 64 and 68 of the other partition walls 18 and 22. [Selection] Figure 4

Description

  The present invention relates to an expansion tank used in a cooling device for an internal combustion engine.

  An expansion tank (reservation tank) used in a cooling device for an internal combustion engine is connected to a cooling liquid circulation passage including a radiator and the like, and stores the cooling liquid so that the cooling liquid can enter and leave the cooling liquid temperature. Absorbs volume fluctuations associated with changes. As an expansion tank, the inside of the tank that stores the coolant is divided into a plurality of storage chambers by a partition between the inlet and the outlet, and the liquid phase part of each storage chamber communicates with the lower communication part provided at the lower part of the partition And the thing of the structure where the gaseous-phase part of each storage chamber is connecting by the upper communication part provided in the upper part of the partition (for example, patent documents 1 and 2).

  In such an expansion tank, gas-liquid separation is performed by raising bubbles in the cooling liquid in a process in which the cooling liquid flows from the chamber on the inlet side to the storage chamber on the outlet side through the lower communication portion. Inflow of bubbles into the circulation passage is avoided.

Japanese Patent Laid-Open No. 6-146883 JP 2014-118884 A

  In the above-described expansion tank, the larger the number of storage chambers that are partitioned by the partition walls, the better the gas-liquid separation, but the volume of each storage chamber becomes smaller. For this reason, when the amount of cooling liquid flowing into the storage chamber becomes larger than the amount of cooling liquid flowing out into the next storage chamber through the lower communication portion, the liquid level in the storage chamber rises, and the air vent opening at the top of the tank is removed. As a result, the liquid level reaches the communication hole (relief port), and the coolant flows out of the communication hole.

  The problem to be solved by the present invention is to prevent the coolant from flowing out from the communication hole even when the amount of coolant flowing into the storage chamber is large.

  The expansion tank according to the present invention includes a tank body (12) defining a storage chamber (15) for storing a coolant therein, and a plurality of chambers (24, 26, 28, 30) dividing the storage chamber into a plurality of chambers (24, 26, 28, 30). Partition walls (16, 18, 20, 22), and the plurality of partition walls (16, 18, 20, 22) communicate with the chambers (24, 26, 28, 30) adjacent to the lower and upper portions, respectively. Including one provided with a lower communication part (32, 34, 36) and an upper communication part (62, 64, 66, 68), one of the plurality of chambers is an inlet having an inlet (44) opened. The other chamber is an outlet chamber (30) having an outlet (40) open, the remaining chambers are at least one intermediate chamber (26, 28), and the outlet chamber (30). ) Has a communication hole (52) open in one of the other chambers. The lower edge of the upper communication portion (62, 66) of the partition wall (16, 20) that divides the chamber (26) in which the communication hole (52) is opened is the upper communication of the other partition wall (18, 22). It is below the lower edge of the part (64, 68).

  According to this configuration, when the liquid level of the chamber (26) in which the communication hole (52) is opened rises, the coolant flows to the other chamber (28) through the upper communication portion (62, 66). The phenomenon that the liquid level in the chamber (26) rises is suppressed. Thereby, it becomes difficult for the liquid level of the chamber (26) to reach the communication hole (52), and it is avoided that the coolant flows out of the communication hole (52).

  In the expansion tank according to the present invention, preferably, the tank body (12) is a box-like shape opened upward, and further includes an upper lid (14) for closing the opening of the tank body (12), and the upper communication is provided. Portions (62, 64, 66, 68) are defined between the plurality of partition walls (16, 18, 20, 22) and an upper lid (14).

  According to this configuration, the upper communication portion (62, 64, 66, 68) is simply configured.

  In the expansion tank according to the present invention, preferably, at least one of the upper communication portions (62, 64, 66, 68) is an upper edge (16A, 18A) of at least a part of the partition wall (16, 18, 20, 22). , 20A, 22A).

  According to this configuration, the opening area of the upper communication portion (62, 64, 66, 68) can be increased.

  In the expansion tank according to the present invention, preferably, the intermediate chamber includes a first intermediate chamber (26) and a second intermediate chamber (28), and a first intermediate chamber (adjacent to the inlet chamber (24)) ( 26) communicates with the communication hole (52), and both the first intermediate chamber (26) and the inlet chamber (24) are adjacent to the second intermediate chamber (28) on the same side. The upper edge (16B, 20B) of the partition wall (16, 20,) separating the first intermediate chamber (26) on the side connected to the partition wall (18) partitioning the second intermediate chamber (24). ) Is higher than the upper edges (16A, 20A) of other parts.

  According to this configuration, it becomes difficult for the coolant to flow directly from the inlet chamber (24) over the upper edges (16A, upper edge 20A) of the partition walls (16, 20) to the second intermediate chamber (28). A reduction in the gas-liquid separation effect due to the direct flow of the coolant from the chamber (24) to the second intermediate chamber (28) is suppressed.

  In the expansion tank according to the present invention, preferably, the communication hole (52) communicates with the first intermediate chamber (26), and the partition wall that separates the first intermediate chamber and the inlet chamber (24). (16) The upper edge (16A) is higher than the upper edge (20A) of the partition wall (20) that separates the first intermediate chamber (26) and the chamber (28) other than the inlet chamber (24). is there.

  According to this configuration, it becomes difficult for the coolant to flow directly from the inlet chamber (24) over the upper edge (16A) of the partition wall (16) to the intermediate chamber (26) and the other chamber (28). The reduction in the gas-liquid separation effect due to the direct flow of the coolant from 24) to the intermediate chamber (26) and the other chamber (28) is suppressed.

  In the expansion tank according to the present invention, preferably, the area of the upper communication portion (62, 66) of the partition wall (16, 20) that divides the chamber (26) through which the communication hole (52) communicates is the communication hole (52). ) Is larger than the area of the lower communication portion (32, 34) of the partition wall (16, 20) separating the chamber (26) in communication.

  According to this configuration, the flow rate of the coolant flowing through the upper communication portions (62, 66) to the other chambers (24, 28) increases, and the liquid level in the chamber (26) becomes the communication hole (52). ) Even more difficult to reach.

  According to the expansion tank of the present invention, when the liquid level in the chamber with the communication hole opened rises, the coolant flows through the upper communication part to the other chamber, so the liquid level in the chamber with the communication hole opened rises. Therefore, the liquid level of the chamber in which the communication hole is opened becomes difficult to reach the communication hole, and the coolant is prevented from flowing out of the communication hole.

The perspective view which shows Embodiment 1 of the expansion tank by this invention The perspective view which shows the state which removed the upper cover of the expansion tank of Embodiment 1. FIG. Sectional view along line III-III in FIG. Sectional view along line IV-IV in FIG. The perspective view which shows the state which removed the upper cover of Embodiment 2 of the expansion tank by this invention. The perspective view which shows the state which removed the upper cover of Embodiment 3 of the expansion tank by this invention.

  Hereinafter, Embodiment 1 of an expansion tank according to the present invention will be described with reference to FIGS. For convenience of explanation, the front and rear, top and bottom, and left and right directions are defined as shown in the figure.

  The expansion tank 10 includes a box-shaped tank body 12 that opens upward and an upper lid 14 that closes the opening of the tank body 12. The tank body 12 and the upper lid 14 are made of plastic, and are joined to each other in an airtight manner by vibration welding or the like. The tank body 12 has a substantially rectangular parallelepiped shape having a tank front wall 12A, a tank rear wall 12B, a tank right wall 12C, a tank left wall 12D, and a tank bottom wall 12E, and defines a cooling liquid storage chamber 15. Yes.

  In the tank body 12, a first partition wall 16, a second partition wall 18, a third partition wall 20, and a fourth partition wall 22 are integrally formed as a ridge wall rising from the tank bottom wall 12E. The partition walls 18, 20, and 22 partition the storage chamber 15 into a plurality of chambers (an inlet chamber 24, a first intermediate chamber 26, a second intermediate chamber 28, and an outlet chamber 30).

  The second partition wall 18 and the third partition wall 20 are in the same left-right position, and the space between the tank front wall 12A and the tank rear wall 12B is continuous in a straight line substantially parallel to the tank right wall 12C. It is extended. In other words, when the second partition wall 18 and the third partition wall 20 are viewed as one partition wall extending between the tank front wall 12A and the tank rear wall 12B, the front half of the partition wall is the second partition wall 18. In addition, the rear half is the third partition wall 20, and the boundary between the second partition wall 18 and the third partition wall 20 exists at an intermediate position in the front-rear direction.

  The first partition 16 extends in a straight line so as to connect the boundary between the second partition 18 and the third partition 20 and the tank right wall 12C at an intermediate position in the front-rear direction in the tank body 12. Exist. Thereby, the 1st partition 16, the 2nd partition 18, and the 3rd partition 20 make a T shape by plane view.

  The fourth partition wall 22 is on the tank left wall 12D side from the second partition wall 18 and the third partition wall 20, and is substantially parallel to the partition walls 18 and 20 between the tank front wall 12A and the tank rear wall 12B. It extends in a straight line.

  As a result, the first partition wall 16 divides the right side of the tank main body 12 into the inlet chamber 24 and the first intermediate chamber 26 forward and backward. The second partition wall 18 divides the front portion in the tank body 12 into the left and right sides into an inlet chamber 24 and a second intermediate chamber 28. The third partition wall 20 divides the rear portion in the tank body 12 into a first intermediate chamber 26 and a second intermediate chamber 28 on the left and right. The fourth partition wall 22 divides the left side portion in the tank body 12 into a second intermediate chamber 28 and an outlet chamber 30 on the left and right sides.

  A first lower communication portion 32 that opens the first inlet chamber 24 and the first intermediate chamber 26 to communicate with each other via the first partition wall 16 is opened at the lower portion of the first partition wall 16. A second lower communication portion 34 that opens the first intermediate chamber 26 and the second intermediate chamber 28 adjacent to each other via the third partition wall 20 is opened below the third partition wall 20. . A third lower communication portion 36 that opens the second intermediate chamber 28 and the outlet chamber 30 adjacent to each other via the fourth partition wall 22 is opened at the lower portion of the fourth partition wall 22.

  The first lower communication portion 32 is an opening extending in the front-rear direction, whereas the second lower communication portion 34 and the third lower communication portion 36 are openings extending in the left-right direction. The lower communication portion 32, the second lower communication portion 34, and the third lower communication portion 36 are different from each other in the direction of opening by 90 degrees. The second lower communication portion 34 and the third lower communication portion 36 are openings in the same direction, but the opening positions are different in the front-rear direction. These lower communication portions 32, 34, and 36 are formed by rectangular communication holes having the tank bottom wall 12E as a lower edge, and the opening areas of the lower communication portions 32, 34, and 36 are the same.

  An outlet nipple 38 is integrally formed at the bottom left of the front side of the tank body 12. The outlet nipple 38 defines an outlet 40 that opens to the bottom of the outlet chamber 30. The outlet nipple 38 is connected to a hose (not shown) that connects the outlet 40 to a coolant circulation passage of an internal combustion engine (not shown).

  An inlet nipple 42 is integrally formed on the upper right side of the upper lid 14. The inlet nipple 42 defines an inlet 44 that opens to the top of the inlet chamber 24. Connected to the inlet nipple 42 is a hose (not shown) that connects the inlet 44 to a coolant circulation passage of an internal combustion engine (not shown).

  A cylindrical supply portion 46 is integrally formed on the upper right side of the rear side of the upper lid 14. The replenishing portion 46 is formed with a replenishing port 48 that opens at the top of the first intermediate chamber 26. An air escape nipple 50 is integrally formed on the side portion of the replenishing portion 46. The air release nipple 50 defines a communication hole (air escape port) 52 that communicates with the first intermediate chamber 26 via the supply port 48. A relief tube 51 whose free end side is bent downward is connected to the air escape nipple 50.

  A filler cap 54 is detachably attached to the upper portion of the replenishing portion 46. The filler cap 54 includes a pressure regulating valve 60 having a valve body 58 biased in the valve closing direction by a spring 56. The pressure regulating valve 60 is closed when the pressure inside the tank (tank internal pressure) is less than a predetermined value, shuts off the communication between the communication hole 52 and the first intermediate chamber 26, and the tank internal pressure is equal to or higher than the predetermined value. Sometimes the valve is opened to establish communication between the communication hole 52 and the first intermediate chamber 26.

  The upper lid 14 defines a first upper communication portion 62 (see FIG. 4) for communicating the inlet chamber 24 and the first intermediate chamber 26 with each other between the upper edge 16A of the first partition wall 16 and the second upper wall 16A. A second upper communication portion 64 (see FIG. 4) for communicating the inlet chamber 24 and the second intermediate chamber 28 with each other is defined between the upper edge 18A of the partition wall 18 and the upper edge of the third partition wall 20. A third upper communication portion 66 (see FIG. 3) that communicates the first intermediate chamber 26 and the second intermediate chamber 28 with each other is defined between the upper edge 22A of the fourth partition wall 22 and the upper edge 22A of the fourth partition wall 22. A fourth upper communication portion 68 (see FIG. 3) is defined between the second intermediate chamber 28 and the outlet chamber 30 to communicate with each other. In other words, these upper communication portions 62, 64, 66, and 68 have the upper edges 16A, 18A, 20A, and 22A of the partition walls 16, 18, 20, and 22 as lower edges, and the partition walls 16, 18, 20, and 22 It is the space | gap which exists above each. The areas of the upper communication portions 62, 64, 66, and 68 are different from each other, but are all larger than the opening areas of the lower communication portions 32, 34, and 36.

  The upper edge 16A of the first partition wall 16 and the upper edge 20A of the third partition wall 20 that divide the first intermediate chamber 26 are the upper edge 18A of the second partition wall 18 and the upper edge 22A of the fourth partition wall 22, respectively. More down by dimension H. In other words, the lower edges of the first upper communication portion 62 and the third upper communication portion 66 are below the lower edges of the second upper communication portion 64 and the fourth upper communication portion 68. The areas of the upper communication portions 62, 64, 66, and 68 are different from each other, but are all larger than the opening areas of the lower communication portions 32, 34, and 36.

  A plurality of ribs 70, 72, 74, 76 are integrally formed at the lower part (bottom part) of the upper lid 14. As shown in FIG. 4, the rib 76 is in front of the inlet 44, and the coolant flowing into the inlet chamber 24 from the inlet 44 collides with the rib 76. Accordingly, the coolant from the inlet 44 is prevented from flowing directly through the first upper communication portion 62 to the first intermediate chamber 26.

  The tank front wall 12 </ b> A forms a shelf 13 in the vicinity of the upper portion of the inlet chamber 24. The shelf 13 shortens the falling distance of the coolant flowing into the inlet chamber 24 from the inlet 44 to reduce foaming of the coolant due to the drop.

  When the flow rate of the coolant flowing from the inlet 44 to the inlet chamber 24 is steady, which is less than a predetermined value, the coolant flowing from the inlet 44 to the inlet chamber 24 passes through the first lower communication portion 32 and the first intermediate chamber 26. To the second intermediate chamber 28 through the second lower communication portion 34, further to the outlet chamber 30 through the third lower communication portion 36, and from the outlet 40 to the outside of the tank. leak. During this steady state, even if the liquid level of the coolant in the inlet chamber 24, the first intermediate chamber 26, the second intermediate chamber 28, and the outlet chamber 30 rises in a similar manner, the liquid level of the first partition 16 The state where the upper edge 16A and the upper edge 20A of the third partition wall 20 are not crossed and the entire gas phase part in the upper part of the tank is communicated by the upper communication parts 62, 64, 66, 68 is maintained. The liquid does not flow beyond the upper edges 16A, 18A, 20A, 22A of the partition walls 16, 18, 20, 22.

  Thereby, in the process in which the coolant flows from the inlet chamber 24 to the outlet chamber 30 via the first intermediate chamber 26 and the second intermediate chamber 28, gas-liquid separation is performed by raising the bubbles in the coolant, The coolant that does not contain bubbles returns to the coolant circulation path.

  When the pressure in the gas phase rises due to the rise in the liquid level, the pressure regulating valve 60 is opened, and the air in the tank is released through the communication hole 52. Thereby, the rise in the tank internal pressure is suppressed.

  When the flow rate of the coolant flowing into the inlet chamber 24 from the inlet 44 exceeds a predetermined value, the liquid level in the inlet chamber 24 is raised by the coolant flowing into the inlet chamber 24 from the inlet 44, and the liquid level is the first partition wall. When the height is higher than the upper edge 16 </ b> A of 16, a part of the coolant flowing into the inlet chamber 24 exceeds the upper edge 16 </ b> A of the first partition wall 16, that is, passes through the upper communication portion 62 to the first intermediate chamber 26. Flowing. As a result, the liquid level of the cooling liquid in the first intermediate chamber 26 rises rapidly, and when the liquid level becomes higher than the upper edge 20A of the third partition wall 20, one of the cooling liquids flowing into the first intermediate chamber 26 is obtained. The portion flows over the upper edge 20 </ b> A of the third partition wall 20 to the second intermediate chamber 28. This means that the coolant in the first intermediate chamber 26 flows out to the second intermediate chamber 28 through the third upper communication portion 66 in addition to the second lower communication portion 34. The rise in the liquid level of the first intermediate chamber 26 is suppressed. This becomes remarkable because the opening area of the third upper communication portion 66 is larger than the opening area of the second lower communication portion 34.

  As a result, the liquid level of the coolant in the first intermediate chamber 26 is not significantly higher than the upper edge 20A of the third partition wall 20, and the liquid level of the coolant in the first intermediate chamber 26 is the upper edge 20A. It does not reach the communication hole 52 that is above. Even if the flow rate of the coolant flowing into the inlet chamber 24 is increased by setting the opening areas of the first upper communication part 62 and the third upper communication part 66 according to the assumed maximum flow rate, the communication is possible. The coolant does not flow out from the hole 52.

  Since the upper edge 18A of the second partition wall 18 and the upper edge 22A of the fourth partition wall 22 are positioned higher than the upper edge 16A of the first partition wall 16 and the upper edge 20A of the third partition wall 20, The overflow of the upper edge 18A of the partition wall 18 and the upper edge 22A of the fourth partition wall 22 is less likely to occur than the overflow of the upper edge 16A of the first partition wall 16 and the upper edge 20A of the third partition wall 20. As a result, the coolant flows directly from the inlet chamber 24 to the second intermediate chamber 28, and the first intermediate chamber 26 passes through the upper portion of the second intermediate chamber 28 and cools to the second intermediate chamber 28. Since it is difficult for the liquid to flow directly, a decrease in gas-liquid separation effect due to overflow is suppressed.

  When removing the filler cap 54 and injecting the cooling liquid into the tank from the replenishing unit 46, if the liquid level in the first intermediate chamber 26 rises rapidly due to the large-scale injection, the first partition 16 from the first intermediate chamber 26 Since it flows to the inlet chamber 24 over the upper edge 16A of the second partition wall and flows to the second intermediate chamber 28 over the upper edge 20A of the third partition wall 20, further rise in the liquid level in the first intermediate chamber 26 occurs. Thus, the coolant is prevented from flowing out of the tank from the replenishing section 46.

  Next, Embodiment 2 of the expansion tank according to the present invention will be described with reference to FIG. 5, parts corresponding to those in FIG. 2 are denoted by the same reference numerals as those in FIG. 2, and description thereof is omitted.

  In the second embodiment, the upper edge 20B of the third partition 20 on the inlet chamber 24 side, that is, the boundary side (front side) with the second partition 18 is positioned higher than the upper edge 20A on the tank rear wall 12B side. is there.

  According to this configuration, it is difficult for the coolant to flow directly from the inlet chamber 24 to the second intermediate chamber 28 beyond the upper edge 16A of the first partition wall 16 and the upper edge 20A of the third partition wall 20. Thereby, the fall of the gas-liquid separation effect | action by a cooling fluid flowing directly from the inlet chamber 24 to the 2nd intermediate chamber 28 is suppressed.

  As shown by the phantom lines in FIG. 5, this action is achieved by connecting the upper edge 16B of the first partition 16 to the second partition 18 and the third partition 20 on the connection side (left side) with the tank right wall 12C. It can be similarly obtained by setting the position higher than the upper edge 16A on the side.

  Next, Embodiment 3 of the expansion tank according to the present invention will be described with reference to FIG. 6, parts corresponding to those in FIG. 2 are denoted by the same reference numerals as those in FIG. 2, and description thereof is omitted.

  In the third embodiment, the upper edge 16A of the first partition wall 16 and the upper edge 20A of the third partition wall 20 are both lower than the upper edge 18A of the second partition wall 18 and the upper edge 22A of the fourth partition wall 22. However, the upper edge 16 </ b> A of the first partition wall 16 is positioned higher than the upper edge 20 </ b> A of the third partition wall 20.

  According to this configuration, it is difficult for the coolant to flow directly from the inlet chamber 24 to the second intermediate chamber 28 beyond the upper edge 16A of the first partition wall 16 and the upper edge 20A of the third partition wall 20, and the inlet port. It becomes difficult for the coolant to flow directly from the chamber 24 to the first intermediate chamber 26 beyond the upper edge 16A of the first partition 16.

  Thereby, the fall of the gas-liquid separation effect | action by a coolant flowing directly from the inlet chamber 24 to the 1st intermediate chamber 26 and the 2nd intermediate chamber 28 is suppressed.

  Although the present invention has been described above with reference to preferred embodiments thereof, the present invention is not limited to such embodiments and can be deviated from the spirit of the present invention, as will be readily understood by those skilled in the art. It is possible to change appropriately within the range not to be. For example, a structure in which only the lower edge of the third upper communication portion 66 is located below the lower edges of the other upper communication portions 62, 64, 68 may be employed. The upper communication portions 62, 64, 66, 68 may be configured by communication holes formed in the upper portions of the partition walls 16, 18, 20, 22.

  In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Expansion tank 12 Tank main body 14 Upper cover 15 Reservoir 16 First partition 16 Second partition 16A Upper edge 16B Upper edge 18 Second partition 18A Upper edge 20 Third partition 20A Upper edge 20B Upper edge 22 Fourth edge Partition wall 22A Upper edge 22A Partition wall 24 Inlet chamber 26 First intermediate chamber 28 Second intermediate chamber 30 Exit chamber 32 First lower communication portion 34 Second lower communication portion 36 Third lower communication portion 40 Outlet 44 Inlet 46 Supply part 48 Supply port 52 Communication hole 54 Filler cap 60 Pressure regulating valve 62 First upper communication part 64 Second upper communication part 66 Third upper communication part 68 Fourth upper communication part

Claims (6)

A tank body defining a storage chamber for storing the coolant therein;
A plurality of partition walls dividing the storage chamber into a plurality of chambers;
The plurality of partition walls include those provided with a lower communication portion and an upper communication portion that allow the adjacent chambers to communicate with each other at a lower portion and an upper portion, respectively.
One of the plurality of chambers forms an entrance chamber with an open entrance, the other chamber forms an exit chamber with an exit open, and the remaining chambers form at least one intermediate chamber,
A communication hole is opened in one of the chambers other than the outlet chamber, and a lower edge of the upper communication portion of the partition wall that divides the chamber through which the communication hole communicates is a lower edge of the upper communication portion of another partition wall. Expansion tank below.   The tank main body is a box-shaped object that opens upward, further includes an upper lid that closes the opening of the tank main body, and the upper communication portion is defined between the plurality of partition walls and the upper lid. The expansion tank according to 1.   The expansion tank according to claim 1 or 2, wherein at least one of the upper communication portions is an opening having an upper edge of at least a part of the partition wall as a lower edge.   The intermediate chamber includes a first intermediate chamber and a second intermediate chamber, and the communication hole communicates with the first intermediate chamber adjacent to the inlet chamber, and the first intermediate chamber and the inlet Both of the chambers are adjacent to the second intermediate chamber on the same side, and the upper edge of the partition that divides the first intermediate chamber is connected to the partition that divides the second intermediate chamber. The expansion tank according to claim 2, wherein the expansion tank is located above an upper edge of the portion.   The communication hole communicates with the first intermediate chamber, and an upper edge of the partition partitioning the first intermediate chamber and the inlet chamber connects the first intermediate chamber and a chamber other than the inlet chamber. The expansion tank according to claim 4, wherein the expansion tank is located at a position higher than an upper edge of the partition wall.   The area of the upper communication part of the partition wall that divides the chamber communicated with the communication hole is larger than the area of the lower communication part of the partition wall that divides the chamber opened by the communication hole. The described expansion tank.

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