Structure of the inlet of the reserve tank

Abstract

To provide a structure for an inflow part of a reserve tank capable of suppressing inclusion of air in a coolant.SOLUTION: In a structure for an inflow part 52 of a reserve tank 5 provided in a coolant circulation circuit, when a side close to a reserve tank body 51 in the inflow part 52 is defined as one end side and a side far from the reserve tank body 51 is defined as the other end side, a flow passage area on the one end side in the inflow part 52 is set larger than that on the other end side. A shape of a flow passage inside the inflow part 52 is a tapered shape in which the flow passage area gradually becomes larger from the other end side toward the one end side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the structure of the inflow part of a reserve tank provided in a coolant circulation circuit.

Background Art

[0002] Conventionally, as disclosed in Patent Document 1, for example, a vehicle is provided with a coolant circulation circuit for cooling a device (heat-generating component) that generates heat, and the device is cooled by the coolant circulating through this coolant circulation circuit. In addition, a reserve tank is provided in this coolant circulation circuit. The reserve tank is used to replenish the coolant circulation circuit with coolant and also has a function of absorbing the volume change due to the thermal expansion of the coolant.

[0003] If air is mixed into the coolant in the reserve tank, there is a possibility that the air will flow out into the coolant circulation circuit, leading to a deterioration in the cooling efficiency of the device.

[0004] In view of this point, Patent Document 2 and Patent Document 3 have been proposed. Patent Document 2 adopts a structure for swirling the coolant in the reserve tank, and by this, it is disclosed that the air mixed into the coolant is separated by centrifugal force. Further, Patent Document 3 provides a partition plate having holes at the lower part in the reserve tank, and while the coolant stays between the partition plates, the air mixed into the coolant is separated.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0006] However, all of these patent documents concern methods for separating air mixed in with the coolant.

[0007] The inventors of this invention considered that preventing air from being mixed into the coolant in the first place is more effective in suppressing the deterioration of cooling efficiency than separating the air mixed into the coolant.

[0008] Figure 6 is a cross-sectional view of the area around the reserve tank a to illustrate the situation in which air (bubbles) c are mixed into the coolant b in the reserve tank a. An inlet e, consisting of a straight pipe, is provided at the lower part of the side wall d of the reserve tank a, and an outlet g is provided at the bottom plate f of the reserve tank a. Coolant b that flows into the reserve tank a from a coolant circulation circuit (not shown) via the inlet e collides with the side wall h of the reserve tank a (the side wall opposite the side wall d where the inlet e is located), causing its streamlines to become upward and fluctuating (wave-like) the liquid level of the coolant b. This fluctuation in liquid level becomes greater the higher the flow velocity of the coolant b flowing into the reserve tank a. As the liquid level of the coolant b fluctuates in this way, air i present in the upper part of the reserve tank a is drawn into the coolant b, resulting in air c being mixed into the coolant b. Furthermore, if this air c flows out from the outlet g into the coolant circulation circuit and circulates through the coolant circulation circuit, it will lead to a deterioration in cooling efficiency. Therefore, in order to suppress the deterioration of cooling efficiency, it is effective to prevent air c from mixing with the coolant b in the reserve tank a.

[0009] The present invention has been made in view of the above, and its objective is to provide a structure for the inlet of a reserve tank that can suppress the mixing of air into the coolant. [Means for solving the problem]

[0010] The present invention provides a solution for achieving the above objective, based on the structure of the inlet of a reserve tank provided in a coolant circulation circuit. In this structure of the inlet of the reserve tank, when the side closer to the reserve tank body in the direction of coolant flow at the inlet is designated as one end and the side further from the reserve tank body as the other end, the flow path area on the one end of the inlet becomes larger than the flow path area on the other end. Furthermore, one end of the inlet is open in a direction intersecting the side wall of the reserve tank body, and the other end of the inlet is open in a direction along the extension of the side wall of the reserve tank body. It is characterized by the following:

[0011] According to this specific design, when coolant flows from the coolant circulation circuit through the inlet into the reserve tank (reserve tank body), the flow area at one end of the inlet (the side closer to the reserve tank body in the direction of coolant flow) is larger than the flow area at the other end (the side further from the reserve tank body in the direction of coolant flow). This allows for a reduction in the coolant flow velocity while suppressing a decrease in the flow rate at the inlet (the amount of coolant flowing into the reserve tank body per unit time). As a result, fluctuations in the coolant level within the reserve tank body due to the coolant flowing in are suppressed. Consequently, air present in the upper part of the reserve tank body is prevented from being drawn into the coolant and mixing with it. As a result, the amount of air flowing into the coolant circulation circuit can be significantly reduced, thereby suppressing a deterioration in cooling efficiency.

[0019] Also, The coolant flowing into the inlet from the other end will flow along the direction extending from the side wall of the reserve tank body, and its flow velocity will decrease as it flows. In other words, compared to a design where the flow velocity decreases as the coolant flows in a direction perpendicular to the side wall of the reserve tank body, it becomes possible to shorten the length of the inlet in the direction perpendicular to the side wall of the reserve tank body. This also makes it possible to miniaturize the inlet while suppressing the mixing of air into the coolant within the reserve tank body. [Effects of the Invention]

[0020] In this invention, the flow path area at one end of the reserve tank inlet is made larger than the flow path area at the other end, which is farther from the reserve tank body. As a result, it is possible to reduce the flow velocity of the coolant while suppressing a decrease in the flow rate at the inlet, and it is possible to suppress the mixing of air present in the upper part of the reserve tank body with the coolant. Consequently, the amount of air flowing into the coolant circulation circuit can be significantly reduced, thereby suppressing a deterioration in cooling efficiency. [Brief explanation of the drawing]

[0021] [Figure 1] This figure shows a schematic configuration of a coolant circulation circuit equipped with a reserve tank according to the embodiment. [Figure 2] This is a cross-sectional view of the area around the reserve tank according to the embodiment. [Figure 3] This is a cross-sectional view showing an enlarged view of the inlet portion of the reserve tank according to the embodiment. [Figure 4] Figure 4(a) shows the inlet of the reserve tank according to the first modified example, where Figure 4(a) is an enlarged cross-sectional view of the inlet, Figure 4(b) is a cross-sectional view in a direction perpendicular to the streamlines when the velocity reduction section of the inlet is frustoconical, and Figure 4(c) is a cross-sectional view in a direction perpendicular to the streamlines when the velocity reduction section of the inlet is frustoconical. [Figure 5] Figure 5(a) is a side view showing the inlet of the reserve tank according to the second modified example, Figure 5(b) is a perspective view showing the inlet of the reserve tank according to the third modified example, and Figure 5(c) is a perspective view showing the inlet of the reserve tank according to the fourth modified example. [Figure 6] This is a cross-sectional view of the area around the reserve tank to illustrate the situation in which air is mixed into the coolant in the reserve tank in the conventional technology. [Modes for carrying out the invention]

[0022] Hereinafter, embodiments of the present invention will be described based on the drawings. This embodiment will describe the case where the present invention is applied as the structure of the inflow part of the reserve tank provided in the coolant circulation circuit in the battery cooling system of an electric vehicle. Note that the coolant circulation circuit to which the present invention can be applied is not limited to the battery cooling system of an electric vehicle, and includes various cooling systems such as the cooling system of an inverter, the cooling system of an electric motor, and the engine cooling system in an engine-mounted vehicle.

[0023] -Schematic configuration of the coolant circulation circuit- FIG. 1 is a diagram showing a schematic configuration of a coolant circulation circuit 1 provided with a reserve tank 5 according to this embodiment. As shown in FIG. 1, the coolant circulation circuit 1 is configured such that a pump 2, a heat exchanger 3, a battery 4 which is a cooling target device (for example, a coolant flow path provided inside the battery), and a reserve tank 5 are connected by a pipe 6 so that the coolant can circulate.

[0024] The pump 2 is, for example, an electric type, and circulates the coolant in the coolant circulation circuit 1 by operating.

[0025] The heat exchanger 3 performs heat exchange between the coolant circulating in the coolant circulation circuit 1 and the outside air, releases the heat of the coolant to the outside air, and thereby cools the coolant. Note that the medium for performing heat exchange with the coolant is not limited to the outside air.

[0026] The battery 4 stores electric power for supplying power to a traveling motor which is a driving power source for traveling of an electric vehicle and other electric devices. The battery 4 generates heat during charging and discharging. In recent electric vehicles, the energy density of the battery 4 has a tendency to increase in order to improve the traveling performance of the vehicle or increase the traveling range. Therefore, efficient cooling of the battery 4 is required. For this reason, it is required to reduce the amount of air in the coolant circulation circuit 1 to suppress deterioration of the cooling efficiency.

[0027] The reserve tank 5 comprises a reserve tank body 51, which is a roughly cylindrical container for storing coolant. This reserve tank body 51 is connected to piping (piping extending from the battery 4) 6 via an inlet 52 and to piping (piping extending to the suction side of the pump 2) 6 via an outlet 53. The reserve tank 5 also has a function to absorb volume changes due to thermal expansion of the coolant. The reserve tank 5 is also used to replenish the coolant in the coolant circulation circuit 1.

[0028] -Reserve Tank Configuration- Next, the configuration of the reserve tank 5 will be described. Figure 2 is a cross-sectional view of the area around the reserve tank 5 according to this embodiment. As shown in Figure 2, the reserve tank 5 is configured to include a reserve tank body 51, an inlet 52 and an outlet 53 integrally connected to the reserve tank body 51.

[0029] The reserve tank body 51 is a roughly cylindrical container and is equipped with side walls 51a, a top plate 51b, and a bottom plate 51c. A predetermined amount of coolant 7 is stored inside the reserve tank body 51. When the amount of coolant 7 stored inside the reserve tank body 51 decreases to a predetermined level (when the liquid level of the coolant 7 drops to a predetermined position), coolant 7 is replenished from the top plate 51b side of the reserve tank body 51 (the replenishment mechanism is well known and is therefore not shown). Note that the reserve tank body 51 is not limited to a roughly cylindrical container and may be a rectangular tubular container.

[0030] An inlet 52 is integrally connected to the lower part of one side wall 51a of the reserve tank body 51 (the side wall located on the left side in Figure 2). In addition, an outlet 53 is integrally connected to the bottom plate 51c of the reserve tank body 51, at a position closer to the side wall 51a' opposite to the side wall 51a to which the inlet 52 is connected (the side wall opposite to side wall 51a: the side wall located on the right side in Figure 2).

[0031] (Structure of the inlet) Next, the structure of the inlet 52, which is a feature of this embodiment, will be described. Figure 3 is an enlarged cross-sectional view of the inlet 52. As shown in Figure 3, the inlet 52 comprises a straight pipe section 52a and a flow velocity reduction section 52b. The straight pipe section 52a is the part that is connected to the piping 6 of the coolant circulation circuit 1, and the flow velocity reduction section 52b is the part that is connected to the side wall 51a of the reserve tank body 51.

[0032] The straight pipe section 52a is formed from a straight pipe whose inner diameter is uniform throughout its entire length. The outer diameter of the straight pipe section 52a is approximately the same as the inner diameter of the pipe 6, and as shown in Figure 2, the pipe 6 and the inlet section 52 are connected by inserting the straight pipe section 52a into the pipe 6. Conversely, the pipe 6 and the inlet section 52 may be connected by inserting the pipe 6 into the straight pipe section 52a. In this embodiment, the inner and outer diameters of the straight pipe section 52a are approximately the same as the inner and outer diameters of the outlet section 53, which is also made of a straight pipe.

[0033] In the flow velocity reduction section 52b, if the side closer to the reserve tank body 51 (the side connected to the reserve tank body 51) is considered one end and the side further from the reserve tank body 51 (the side connected to the straight pipe section 52a) is considered the other end, the flow path area on one end is larger than the flow path area on the other end. More specifically, the flow path shape inside the flow velocity reduction section 52b is a tapered shape in which the flow path area gradually increases from the other end to the one end.

[0034] Thus, because the flow path area on one end of the flow velocity reduction section 52b is larger than the flow path area on the other end, the coolant flowing from the pipe 6 into the inlet section 52 (coolant 7 with flow velocity V1 in Figure 3) decreases in flow velocity (flow velocity V2 in Figure 3) while suppressing a decrease in the flow rate in the inlet section 52 (the amount of coolant 7 that flows into the reserve tank body 51 per unit time). <V1)となる)ようになっている。

[0035] More specifically, the inclination angle (opening angle) θ of the tapered shape of the flow path inside the flow velocity reduction section 52b is set to less than 5°. This is because if the inclination angle θ of the tapered shape is too large, separation of the coolant 7 may occur on the inner surface of the inlet section 52, and this is to suppress that. In other words, if separation of the coolant 7 occurs on the inner surface of the inlet section 52, a dead zone may be created as a result, making it impossible to reduce the flow velocity of the coolant 7. In view of this, the inclination angle of the tapered shape is defined as described above to suppress separation of the coolant 7 on the inner surface of the inlet section 52 and to suppress the occurrence of a dead zone, thereby enabling a reduction in the flow velocity of the coolant 7.

[0036] Given the configuration of the flow velocity reduction section 52b, if the cross-sectional area of ​​the other end of the flow velocity reduction section 52b (the upstream end in the flow direction of the coolant 7) is A1 and the cross-sectional area of ​​the one end (the downstream end in the flow direction of the coolant 7) is A2, then in order to reduce the flow velocity of the coolant 7 to a predetermined flow velocity while maintaining the aforementioned inclination angle θ of the tapered shape, the larger the ratio C = A2 / A1, the longer the length of the flow velocity reduction section 52b needs to be.

[0037] -Coolant flow status- Next, we will explain the flow of coolant 7 into the reserve tank body 51 due to the inlet 52 configured as described above. The dashed arrows in Figure 2 indicate the flow of coolant 7 into the reserve tank body 51 and the flow of coolant 7 out of the reserve tank body 51 to the coolant circulation circuit 1.

[0038] The coolant 7 that flows from the piping 6 of the coolant circulation circuit 1 into the inlet 52 passes through the straight pipe section 52a and then flows through the velocity reduction section 52b. The flow path shape inside this velocity reduction section 52b is tapered, with the flow path area gradually increasing in the direction of coolant 7 flow. This reduces the flow velocity of the coolant 7 while preventing a decrease in the flow rate of the coolant 7 at the inlet 52 (the amount of coolant 7 that flows into the reserve tank body 51 per unit time). As a result, the flow velocity of the coolant 7 that flows into the reserve tank body 51 also decreases.

[0039] In conventional technology, the coolant flowing into the reserve tank (a coolant with a relatively high flow rate) would collide with the side wall of the reserve tank (the side wall opposite the side wall where the inlet is located), causing its streamlines to become upward. This fluctuation in the coolant level made it highly likely that air present in the upper part of the reserve tank would be drawn into the coolant. As a result, air would flow out from the outlet into the coolant circulation circuit, leading to a deterioration in cooling efficiency.

[0040] In contrast, in this embodiment, since the flow velocity of the coolant 7 flowing into the reserve tank body 51 is reduced, fluctuations in the liquid level of the coolant 7 are suppressed, thereby preventing air A present in the upper part of the reserve tank body 51 from being drawn into the coolant 7. As a result, the amount of air flowing into the coolant circulation circuit 1 can be significantly reduced, thereby suppressing deterioration of cooling efficiency.

[0041] -Effects of the embodiment- As explained above, in this embodiment, the flow path area on one end of the inlet 52 of the reserve tank 5, which is closer to the reserve tank body 51, is made larger than the flow path area on the other end, which is further from the reserve tank body 51. Therefore, it is possible to reduce the flow velocity of the coolant 7 while suppressing a decrease in the flow rate at the inlet 52, and it is possible to suppress the air A present in the upper part of the reserve tank body 51 from being drawn into the coolant 7 and mixing air into the coolant 7. As a result, the amount of air flowing out into the coolant circulation circuit 1 can be significantly reduced, and the deterioration of cooling efficiency can be suppressed. And because the deterioration of cooling efficiency can be suppressed in this way, efficient cooling of the battery 4 becomes possible, which can contribute to improving the energy consumption rate (electricity consumption).

[0042] Furthermore, the inventor of the present invention calculated the amount of air flowing out from the outlet 53 (the amount of air flowing into the coolant circulation circuit 1) by numerical analysis. Specifically, in the conventional technology, the ratio of the cross-sectional area of ​​the downstream end to the upstream end of the inlet was set to 1, while in the present invention, the ratio of the cross-sectional area of ​​the downstream end to the upstream end of the inlet 52 was set to 2. As a result, it was confirmed that the amount of air flowing out from the outlet 53 of the reserve tank 5 according to the present invention was reduced by approximately 50% compared to the reserve tank of the conventional technology. This confirmed that the deterioration of cooling efficiency can be suppressed.

[0043] -First variation- Next, a first modified example will be described. In this modified example, the configuration of the flow velocity reduction section 52b, in particular the internal configuration of the flow velocity reduction section 52b, differs from that of the previously described embodiment. Since the other configurations are the same as those of the above embodiment, only the differences from the above embodiment will be described here.

[0044] Figure 4 shows the inlet 52A of the reserve tank 5 according to this modified example, where Figure 4(a) is an enlarged cross-sectional view of the inlet 52A, and Figure 4(b) is a cross-sectional view in a direction perpendicular to the streamlines when the flow velocity reduction section 52b of the inlet 52A is frustoconical in shape.

[0045] As shown in these figures, the flow velocity reduction section 52b in this modified example is provided with multiple guide vanes 52c, 52c, ... that divide the flow path of the coolant 7 flowing inside it into multiple paths. Each guide vane 52c extends horizontally as shown in Figure 4(b) and both ends are connected to the inner surface of the flow velocity reduction section 52b. As a result, multiple independent flow paths are formed inside the flow velocity reduction section 52b in the vertical direction. Furthermore, the inclination angle (angle of inclination with respect to the horizontal direction) of each guide vane 52c, 52c, ... is larger for guide vanes 52c located on the outside (located on the outside in the vertical direction). More specifically, the inclination angles of each guide vane 52c, 52c, ... are arranged so that the angle they make with adjacent wall surfaces (the inner surface of the flow velocity reduction section 52b or the wall surface of the adjacent guide vane 52c) is less than a predetermined angle (for example, 5°).

[0046] When guide vanes 52c, 52c, ... are provided inside the flow velocity reduction section 52b in this manner, the direction of the coolant streamlines can be changed (slightly shifted outward) by the inner surface of the flow velocity reduction section 52b (e.g., a tapered surface) or the surface of the guide vanes 52c. This makes it possible to increase the inclination angle of the flow path shape (the rate of expansion of the cross-sectional area inside the flow velocity reduction section 52b) while reducing the angle between the direction of the coolant streamlines and the inner surface of the flow velocity reduction section 52b or the surface of the guide vanes 52c. As a result, while suppressing the separation of the coolant 7, it becomes possible to shorten the length of the inlet section 52A required to reduce the flow velocity of the coolant 7 flowing into the reserve tank body 51 to a predetermined flow velocity (a flow velocity that suppresses the mixing of air into the coolant 7 inside the reserve tank body 51). As a result, the inlet section 52A can be miniaturized while suppressing the mixing of air into the coolant 7 inside the reserve tank body 51.

[0047] Figure 4(c) is a cross-sectional view taken perpendicular to the streamlines when the velocity reduction section 52b of the inlet section 52A is shaped like a truncated square pyramid. In the configuration shown in Figure 4(c), multiple guide vanes 52c, 52c, ... are provided inside the velocity reduction section 52b. In this configuration, as described above, it is possible to shorten the length of the inlet section 52A required to reduce the flow velocity of the coolant 7 flowing into the reserve tank body 51 to a predetermined flow velocity while suppressing the separation of the coolant 7. Therefore, it is possible to miniaturize the inlet section 52A while suppressing the mixing of air into the coolant 7 inside the reserve tank body 51.

[0048] -Second variation- Next, a second modified example will be described. In this modified example, the configuration of the flow velocity reduction section 52b differs from that of the previously described embodiment. The other configurations are the same as those of the previous embodiment, so here again, only the differences from the previous embodiment will be described.

[0049] Figure 5(a) is a side view showing the inlet 52B of the reserve tank 5 according to this modified example. As shown in Figure 5(a), the flow velocity reduction section 52b of the inlet 52B according to this modified example has an enlarged diameter section 52d, a cylindrical section 52e, and a reduced diameter section 52f, which are integrally arranged along the flow direction of the coolant 7.

[0050] The enlarged diameter section 52d has a tapered flow path shape within it, where the flow path area gradually increases from the other end to the one end. Therefore, the upstream side of the enlarged diameter section 52d in the direction of coolant flow (left side in Figure 5(a)) corresponds to the "other end side, which is farther from the reserve tank body" in this invention, and the downstream side of the enlarged diameter section 52d in the direction of coolant flow (right side in Figure 5(a)) corresponds to the "one end side, which is closer to the reserve tank body" in this invention.

[0051] Furthermore, a pressure loss member 52g (shown as a dashed line in Figure 5(a)) made of mesh material or a porous material is housed inside the cylindrical portion 52e. The shape of this pressure loss member 52g is cylindrical, which substantially matches the shape of the inside of the cylindrical portion 52e. As a result, pressure loss is added to the coolant 7 as it passes through the inside of the cylindrical portion 52e. Therefore, the flow velocity of the coolant 7 that flows into the inlet portion 52B is reduced in the enlarged diameter portion 52d, and separation is less likely to occur. For this reason, the inclination angle of the flow path inside the enlarged diameter portion 52d can be increased, and even if this inclination angle is set to 5° or more, separation will still be less likely to occur. Therefore, while suppressing the separation of the coolant 7, it is possible to shorten the length of the inlet portion 52B required to reduce the flow velocity of the coolant 7 flowing into the reserve tank body 51 to a predetermined flow velocity. This also makes it possible to reduce the size of the inlet section 52B while suppressing the mixing of air into the coolant 7 within the reserve tank body 51.

[0052] Furthermore, the reason for providing a reduced-diameter section 52f downstream of the cylindrical section 52e is to address the possibility of disturbance in the velocity distribution of the coolant 7 as it flows through the cylindrical section 52e and passes through the pressure loss member 52g, and to ensure that the flow of the coolant 7 is rectified before it flows into the reserve tank body 51.

[0053] -Third variation- Next, a third modified example will be described. In this modified example, the overall configuration of the inlet 52 differs from that of the previously described embodiment. The other configurations are the same as those of the previous embodiment, so here again, only the differences from the previous embodiment will be described.

[0054] Figure 5(b) is a perspective view showing the inlet 52C of the reserve tank 5 according to this modified example. As shown in Figure 5(b), the inlet 52C according to this modified example has an upstream straight pipe section 52h, a cylindrical section 52i, and a downstream straight pipe section 52j arranged integrally.

[0055] The upstream straight pipe section 52h extends in the vertical direction (along the extension direction of the side wall 51a of the reserve tank body 51). Furthermore, the upstream end of this upstream straight pipe section 52h, in the direction of coolant flow 7, is open downwards, and this open portion is connected to the piping 6.

[0056] The cylindrical section 52i is formed in a cylindrical shape with its centerline oriented horizontally (in the direction intersecting the side wall 51a of the reserve tank body 51). The upstream straight pipe section 52h is connected to this cylindrical section 52i from the lower side in the tangential direction to the outer surface of the cylindrical section 52i. Therefore, when coolant 7 flows from the upstream straight pipe section 52h into the cylindrical section 52i, the coolant 7 flows inside the cylindrical section 52i as a swirling flow along the inner surface of the cylindrical section 52i. Furthermore, because the internal area of ​​the cylindrical section 52i (the area in the direction perpendicular to the direction of the streamlines of the swirling flow) is larger than the flow path area of ​​the upstream straight pipe section 52h, the flow velocity of the coolant 7 is reduced. Therefore, the portion of the cylindrical portion 52i to which the upstream straight pipe portion 52h is connected corresponds to the "other end side, which is the side furthest from the reserve tank body" in this invention, and the downstream portion of the internal space of the cylindrical portion 52i in the direction of the flow of the coolant 7 corresponds to the "one end side, which is the side closer to the reserve tank body" in this invention.

[0057] Furthermore, the downstream straight pipe section 52j is connected to the center of the side wall of the cylindrical section 52i that faces the reserve tank body 51, and its opening direction is horizontal (intersecting the side wall 51a of the reserve tank body 51), and this opening is connected to the side wall 51a of the reserve tank body 51. In addition, the inner diameter of this downstream straight pipe section 52j is set to be larger than the inner diameter of the upstream straight pipe section 52h, so that the flow velocity of the coolant 7 does not become too high when it flows through the inside of this downstream straight pipe section 52j.

[0058] In this modified example, the coolant 7 that flows into the inlet 52C flows along the direction of extension of the side wall 51a of the reserve tank body 51, and its flow velocity decreases as it flows. In other words, compared to a design where the flow velocity decreases as it flows in a direction intersecting the side wall 51a of the reserve tank body 51, it becomes possible to shorten the length of the inlet 52C in the direction intersecting the side wall 51a of the reserve tank body 51. This also makes it possible to miniaturize the inlet 52C while suppressing the mixing of air into the coolant 7 within the reserve tank body 51.

[0059] -Fourth variation- Next, we will describe the fourth modification. This modification differs from the third modification described above in the configuration of the upstream straight pipe section 52h. The other configurations are the same as those of the third modification, so here we will only explain the differences from the third modification.

[0060] Figure 5(c) is a perspective view showing the inlet 52D of the reserve tank 5 according to this modified example. As shown in Figure 5(c), the inlet 52D according to this modified example also has a configuration in which the upstream straight pipe section 52h, the cylindrical section 52i, and the downstream straight pipe section 52j are integrally arranged. The configuration of the cylindrical section 52i and the downstream straight pipe section 52j is the same as that of the third modified example described above.

[0061] The upstream straight pipe section 52h extends in the vertical direction (the direction in which the side wall 51a of the reserve tank body 51 extends). Furthermore, the upstream end of this upstream straight pipe section 52h is open upward in the direction of the flow of the coolant 7, and this open portion is connected to the piping 6. The upstream straight pipe section 52h is connected to the cylindrical section 52i from the upper side in the tangential direction of the outer surface of the cylindrical section 52i.

[0062] In this modified example, the coolant 7 that flows into the inlet 52D flows along the direction of extension of the side wall 51a of the reserve tank body 51, and its flow velocity decreases as it flows. In other words, compared to a design where the flow velocity decreases as the coolant flows in a direction intersecting the side wall 51a of the reserve tank body 51, it becomes possible to shorten the length of the inlet 52D in the direction intersecting the side wall 51a of the reserve tank body 51. This also makes it possible to miniaturize the inlet 52C while suppressing the mixing of air into the coolant 7 within the reserve tank body 51.

[0063] Furthermore, in the configurations of the third and fourth modified examples described above, the opening direction of the upstream straight pipe section 52h can be arbitrarily set, thus providing greater flexibility in mounting the reserve tank 5 on the vehicle.

[0064] -Other Embodiments- Furthermore, the present invention is not limited to the embodiments and their respective modifications, and all modifications and applications encompassed within the scope of the claims and equivalents thereof are possible.

[0065] For example, in the above embodiment and each of the above modifications, the reserve tank 5 was constructed by integrally molding the reserve tank body 51, the inlet section 52 (52A, 52B, 52C, 52D), and the outlet section 53. The present invention is not limited to this, and the reserve tank 5 may also be constructed by separately molding the reserve tank body 51, the inlet section 52 (52A, 52B, 52C, 52D), and the outlet section 53, and then integrally assembling them.

[0066] Furthermore, in the above embodiment and the first modification, the shape of the flow velocity reduction section 52b is a tapered shape in which the flow path area gradually increases from the other end (the side farther from the reserve tank body 51 in the flow direction of the coolant 7) to the one end (the side closer to the reserve tank body 51 in the flow direction of the coolant 7) over the entire circumference. The present invention is not limited to this, and a part of the periphery of the flow velocity reduction section 52b may be inclined from the other end to the one end so that the flow path area gradually increases (for example, only the upper part of the flow velocity reduction section 52b may be in a shape that expands upward). Also, the flow path shape inside the inlet section 52 only needs to be such that the flow path area on the one end is larger than the flow path area on the other end, and it does not necessarily have to be a tapered shape. For example, the inner surface of the inlet section 52 may be stepped so that the flow path area on the one end is larger than the flow path area on the other end. [Industrial applicability]

[0067] The present invention is applicable to the structure of the inlet of a reserve tank provided in a coolant circulation circuit in the battery cooling system of an electric vehicle. [Explanation of symbols]

[0068] 1 Coolant circulation circuit 5 Reserve Tank 51 Reserve Tank Body 52 Inlet 52b Flow velocity reduction section 52c Guide vane 52g pressure loss component 7 Coolant

Claims

[Claim 1] The structure of the inlet of a reserve tank provided in a coolant circulation circuit, When the side of the coolant flow direction in the inlet is considered one end and the side further from the reserve tank is considered the other end, the flow area on the one end is larger than the flow area on the other end in the inlet. The structure of the inlet of a reserve tank, characterized in that one end of the inlet is open in a direction intersecting the side wall of the reserve tank body, and the other end of the inlet is open in a direction along the extension direction of the side wall of the reserve tank body.

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