Battery cooling device

Abstract

The utility model provides a kind of battery cooling device capable of inhibiting the temperature uneven occurrence inside single cell.Battery cooling device has cooling flow path to the battery pack from upstream battery pack to downstream battery pack, cooling flow path includes first branch flow path and second branch flow path for cooling battery pack, first branch flow path is cooled to upstream battery pack at higher position than second branch flow path, and it is cooled to downstream battery pack at lower position than second branch flow path.

Description

Technical Field

[0001] This disclosure relates to a battery cooling device. Background Technology

[0002] In recent years, technologies related to cooling methods for battery packs composed of multiple individual cells have been disclosed. Here, an individual cell is also referred to as a battery unit. Furthermore, a battery pack can be referred to as a battery module or a battery pack. For example, the energy storage device disclosed in Patent Document 1 has a cooler installed on the opposite side of the battery pack, and a vertical wall portion of a frame is installed on the outside of the cooler. The cooler includes multiple cooling pipes in which a liquid refrigerant flows. The vertical wall portion is composed of an opposite portion and a back portion opposite to the cooler, and the opposite portion and the back portion are formed of materials with different coefficients of thermal expansion. When the cooler is activated, it cools not only the individual cells but also the vertical wall portion of the frame, so the vertical wall portion bends and deforms to press the cooler against the individual cells. As a result, the cooler can effectively cool the individual cells.

[0003] Patent document 1: Japanese Patent Application Publication No. 2018-106958.

[0004] In the cooler disclosed in Patent Document 1, the same cooling performance can be achieved for the battery pack as long as the flow rate of the cooling medium in each cooler is the same. However, when the installation height of the coolers differs, for example, if the coolers are respectively installed on the upper and lower surfaces of the battery pack in the vertical direction (direction of gravity), if the cooling flow paths of the upper and lower surfaces share a portion of the flow path in a certain section, the flow rate of the cooling medium between the upper and lower surfaces may differ during the upward and downward splitting of the cooling flow path. This phenomenon may occur, for example, when the cooler pump is controlled at a constant discharge pressure, due to the influence of gravity, causing changes in the flow velocity on the upper and lower surfaces. When the flow rate of the cooling medium on the upper and lower surfaces differs, the heat dissipation effect on the upper and lower surfaces will differ. As a result, uneven temperature occurs inside the individual cells within the battery pack. Uneven temperature refers to a state where there is a temperature difference inside the individual cells. Utility Model Content

[0005] This disclosure was made in view of the above circumstances, and its purpose is to provide a battery cooling device capable of suppressing temperature unevenness inside a single cell.

[0006] This specification discloses a battery cooling device as a first embodiment, which includes a cooling flow path for cooling multiple battery packs from an upstream battery pack to a downstream battery pack. The cooling flow path includes a first branch flow path and a second branch flow path for cooling the battery packs. The first branch flow path cools the upstream battery pack at a position higher than the second branch flow path and cools the downstream battery pack at a position lower than the second branch flow path.

[0007] Therefore, the battery cooling device of this disclosure, by swapping the vertical positional relationship between the cooling positions of the first branch flow path and the second branch flow path between the upstream and downstream battery packs, can suppress the flow rate differences between the branch flow paths in the downstream battery pack, thereby suppressing the differences in cooling performance between the branch flow paths. Thus, the battery cooling device of this disclosure can suppress the occurrence of uneven temperature within a single cell.

[0008] The second method is as follows: in the first method described above, the first branch flow path flows obliquely downward in the direction of gravity from the upstream battery pack toward the downstream battery pack, and the second branch flow path flows obliquely upward in the direction of gravity from the upstream battery pack toward the downstream battery pack.

[0009] The third method is as follows: In the first method described above, the first branch flow path cools the upstream battery pack from the upper surface in the direction of gravity and cools the downstream battery pack from the lower surface in the direction of gravity; the second branch flow path cools the upstream battery pack from the lower surface in the direction of gravity and cools the downstream battery pack from the upper surface in the direction of gravity.

[0010] The fourth method is that, in the first method described above, the first branch flow path cools the upstream battery pack at a position higher than the second branch flow path, and cools the downstream battery pack adjacent to the upstream battery pack at a position lower than the second branch flow path.

[0011] The fifth method is that, in the third method described above, at least one or both of the first branch flow path and the second branch flow path bends relative to the direction of travel of the branch flow path between the upstream battery pack and the downstream battery pack.

[0012] According to this disclosure, a battery cooling device is provided that can suppress temperature unevenness inside a single cell. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the battery system involved in this disclosure.

[0014] Figure 2 This diagram illustrates an example of a conventional battery cooling device.

[0015] Figure 3 This is a schematic diagram of a traditional battery cooling system cooling four battery packs.

[0016] Figure 4 This is a schematic diagram of the battery cooling device involved in this disclosure cooling four battery packs.

[0017] Figure 5 This is a schematic diagram of the pressure loss generated by a conventional battery cooling device and the battery cooling device of this disclosure. Detailed Implementation

[0018] The embodiments involved in this disclosure will be described below with reference to the accompanying drawings. Figure 1 This is a schematic diagram of the battery system 1 disclosed herein. The battery system 1 includes multiple battery casings 2 and a battery cooling device 3. The battery system 1 is primarily installed in vehicles. Vehicles equipped with the battery system 1 are vehicles that operate using electricity as part of their power source. Specifically, this refers to HEV (Hybrid Electric Vehicle), BEV (Battery Electric Vehicle), PHEV (Plug-in Hybrid Electric Vehicle), FCEV (Fuel Cell Electric Vehicle), etc. The components of the battery system 1 are described in detail below.

[0019] Battery casing 2 is a frame that houses the battery pack (not shown). A battery pack is a rechargeable secondary battery constructed by arranging multiple individual cells connected in series within it. The battery pack can be a lithium-ion battery, a nickel-metal hydride battery, or other types of secondary batteries. Battery packs are typically rectangular in shape.

[0020] The shape of a single cell can be square, cylindrical, oval, or stacked. Furthermore, when a single cell has electrode terminals, the battery pack can configure the single cell so that its electrode terminals face horizontally or vertically. For example, if a single cell normally has vertical electrode terminals, the battery pack can also lay the single cell horizontally with its electrode terminals facing horizontally.

[0021] When individual cells are stacked in a predetermined direction, the stacking direction can be either horizontal or vertical. That is, in this case, Figure 1 The individual cells in the array can be arranged in the X-axis direction, the Y-axis direction, or the Z-axis direction. Stacked individual cells are also called battery stacks.

[0022] Multiple battery packs can be arranged in any orientation. They can be arranged side-by-side horizontally or vertically. When the battery pack is rectangular, and its length is horizontal, multiple battery packs can be arranged at intervals along that length. Alternatively, multiple battery packs can be arranged at intervals along the shorter side of the horizontal plane of the battery pack. Furthermore, multiple battery packs can also be arranged at intervals in the vertical direction. Figure 1 In the middle, multiple battery packs are arranged in the X-axis direction.

[0023] At least a portion of the battery casing 2 is formed of a material with high thermal conductivity. In other words, the battery casing 2 has surfaces that allow heat exchange between the heat generated by the housed battery pack and the outside of the battery casing 2. That is, all surfaces of the battery casing 2 can be formed of a material with high thermal conductivity. Specifically, a portion of the battery casing 2 can be formed of a metal such as aluminum or copper, or the entire battery casing 2 can also be formed of a metal such as aluminum or copper.

[0024] The battery casing 2 can be formed to house the entire battery pack, or it can be formed to cover only a portion of the battery pack. For example, the battery casing 2 can be formed to cover only the vertically opposite surfaces of the battery pack, or it can be formed to cover only the horizontally opposite surfaces. Alternatively, the battery casing 2 can be formed to cover two non-opposing surfaces of the battery pack. Furthermore, the battery casing 2 can also be formed to integrally cover multiple battery packs. For example, the battery casing 2 can be formed to integrally cover two battery packs, or it can be formed to integrally cover three or more battery packs. Figure 1 In the middle, the battery casing 2 houses an entire battery pack.

[0025] The battery casing 2 is formed with a surface made of a material with high thermal conductivity, arranged along the battery pack. This is to facilitate heat exchange between the individual cells within the battery pack and the external structure of the battery casing 2. That is, this surface in the battery casing 2 can be in contact with the battery pack, or it can be formed with a small gap separating it from the battery pack. On the other hand, if the battery casing 2 has a surface not made of a material with high thermal conductivity, this surface can be formed outside the battery pack, or there can be sufficient space between it and the surface of the battery pack opposite to this surface. For example, if the battery pack is cuboid, the battery casing 2 can also be formed in a cuboid shape to cover the shape of the battery pack. Figure 1 In the battery casing 2, the entire casing is made of a material with high thermal conductivity.

[0026] Next, the battery cooling device 3 will be described. The battery cooling device 3 is a device used to remove heat generated in individual cells and lower their temperature by exchanging heat with the individual cells housed within the battery pack in the battery casing 2. The battery cooling device 3 uses a cooling medium to cool the battery pack. The cooling medium is primarily a coolant such as water, but air can also be used. The use of a coolant as the cooling medium in the battery cooling device 3 will be described later.

[0027] The battery cooling device 3 includes a cooling flow path 30 and a coolant pump. The cooling flow path 30 is the piping through which the coolant flows. That is, the cooling flow path 30 is the part of the battery cooling device 3 that directly exchanges heat with the individual cells in the battery pack. Cooling the battery pack by the battery cooling device 3 means that heat is exchanged between the coolant on the cooling flow path 30 and the individual cells in the battery pack.

[0028] The cooling flow path 30 is formed of a material with high thermal conductivity. For example, the cooling flow path 30 is formed of a metal such as copper.

[0029] The cooling flow path 30 can be either entirely filled with coolant or only partially filled with coolant. Furthermore, the cooling flow path 30 can be formed in either a cylindrical or rectangular shape. Figure 1 In the middle, the cooling flow path 30 is formed in the shape of a cuboid.

[0030] A coolant pump circulates coolant along cooling flow path 30, delivering it to battery casing 2. This allows the coolant to exchange heat with the individual cells within battery casing 2, thus cooling the individual cells. Figure 1 The coolant pump is not shown in the image.

[0031] The coolant pump is controlled, for example, to maintain a constant spray pressure. That is, the coolant pump increases the coolant pressure to a predetermined value and controls the spray by compensating for pressure loss (pressure drop) caused by coolant eddies due to factors such as friction between the coolant and the wall of the cooling flow path 30 and path bends.

[0032] The battery cooling device 3 can be configured as a single device to cool multiple battery packs, or as two or more devices to cool multiple battery packs. Specifically, the battery cooling device 3 can be configured with a single cooling flow path 30 and a coolant pump for each of the multiple battery packs, or it can be configured with two or more systems for each of the multiple battery packs. Furthermore, the battery cooling device 3 can also be configured with only one coolant pump for each of the multiple battery packs, and with cooling flow paths 30 corresponding to the number of battery packs. In this case, the number of cooling flow paths 30 can be less than or more than the number of battery packs.

[0033] The cooling flow path 30 is designed to cool two or more battery packs. In other words, two or more battery packs are connected in series in the cooling flow path 30. When one battery pack is housed in a single battery housing 2, the cooling flow path 30 is designed to pass through two or more battery housings 2. When one battery housing 2 houses two or more battery packs, the cooling flow path 30 can also be designed to cool two or more battery packs housed in one battery housing 2. Figure 1 In the middle, the cooling flow path 30 is designed to cool the two battery housings 2, each housing a battery pack.

[0034] The coolant flow path is designed so that coolant sprayed from the coolant pump cools two or more battery packs via the cooling flow path 30 and returns to the pump. Here, in the case of two battery packs cooled by a single cooling flow path 30, the battery pack initially cooled by the cooling flow path 30 is referred to as the upstream battery pack, and the battery pack subsequently cooled is referred to as the downstream battery pack. The upstream and downstream battery packs may or may not be adjacent. Figure 1 In the middle, the battery casing 2a houses the upstream battery pack, and the battery casing 2b houses the downstream battery pack.

[0035] The cooling flow path 30 has a branch point 31, an upstream upper branch flow path 32, an upstream lower branch flow path 33, a descending flow path 34, an ascending flow path 35, a downstream upper branch flow path 36, a downstream lower branch flow path 37, and a confluence point 38. The following describes each component.

[0036] First, the branch point 31 will be explained. Branch point 31 is the location in the cooling flow path 30 where a flow path branches into an upstream upper branch flow path 32 and an upstream lower branch flow path 33. Branch point 31 is further positioned upstream of the upstream battery pack, i.e., at the outlet side of the coolant pump. Branch point 31 branches the upstream upper branch flow path 32 to a higher position than the upstream lower branch flow path 33.

[0037] Branch point 31 may not necessarily branch the upstream upper branch flow path 32 to a position higher than the height of branch point 31. Additionally, branch point 31 may not necessarily branch the upstream lower branch flow path 33 to a position lower than the height of branch point 31. That is, branch point 31 and the upstream upper branch flow path 32 can be at the same height, and branch point 31 and the upstream lower branch flow path 33 can also be at the same height. Branch point 31 can have a T-shape or a Y-shape. Figure 1 In the middle, the branch point 31 has a T-shape, which branches the upstream upper branch flow path 32 to a position higher than the branch point 31, and branches the upstream lower branch flow path 33 to a position lower than the branch point 31.

[0038] Next, the upstream upper branch flow path 32 and the upstream lower branch flow path 33 will be described. The upstream upper branch flow path 32 and the upstream lower branch flow path 33 are branch flow paths that branch off via branch point 31. The upstream upper branch flow path 32 is also referred to as the first branch flow path. Furthermore, the upstream lower branch flow path 33 is also referred to as the second branch flow path. From this point forward, the upstream upper branch flow path 32 and the upstream lower branch flow path 33 will be collectively referred to as the upstream branch flow path.

[0039] The upstream branch flow path is configured along the battery housing 2, thereby cooling the upstream battery pack. Specifically, the upstream branch flow path is configured close to a surface in the battery housing 2 that houses the upstream battery pack, formed of a material with high thermal conductivity. Here, the upstream branch flow path can be in contact with this surface of the battery housing 2, or it can be configured to be isolated from the battery housing 2 with a small gap. Furthermore, the upstream branch flow path can have a width equal to the width of this surface of the battery housing 2 relative to the direction of coolant travel, or it can be wider or narrower than the width of this surface. Moreover, the upstream branch flow path can be straight or curved. Figure 1 In the middle, the upstream branch flow path is designed to be narrower than the width of the opposite battery casing 2a.

[0040] The upstream upper branch flow path 32 cools the upstream battery pack from a higher position relative to the upstream lower branch flow path 33. Therefore, the upstream upper branch flow path 32 is positioned higher than the upstream lower branch flow path 33. The upstream upper branch flow path 32 and the upstream lower branch flow path 33 can be configured to be close to opposite faces of the battery housing 2, close to non-opposing faces, or both close to one side of the battery housing 2.

[0041] For example, if the battery casing 2 has a cuboid shape, the upstream upper branch flow path 32 and the upstream lower branch flow path 33 can be respectively disposed on the upper and lower surfaces in the vertical direction. Alternatively, the upstream branch flow path can also be disposed on the side opposite to the direction of travel. Furthermore, the upstream upper branch flow path 32 can also be disposed on the upper surface relative to the vertical direction, and the upstream lower branch flow path 33 can also be disposed on the side relative to the direction of travel. Additionally, both the upstream upper branch flow path 32 and the upstream lower branch flow path 33 can be disposed on one side relative to the direction of travel. Figure 1 In the middle, the upstream upper branch flow path 32 is disposed on the vertical upper surface of the battery housing 2a, and the upstream lower branch flow path 33 is disposed on the vertical lower surface of the battery housing 2a.

[0042] The upstream upper branch flow path 32 and the upstream lower branch flow path 33 can also be configured to face two or more surfaces of the battery housing 2. For example, if the battery housing 2 is cuboid in shape and both the upstream upper branch flow path 32 and the upstream lower branch flow path 33 have U-shaped cross-sections, the upstream upper branch flow path 32 can be configured on the upper side of the cuboid of the battery housing 2, and the upstream lower branch flow path 33 can be configured on the lower side of the cuboid of the battery housing 2. In this case, the upstream upper branch flow path 32 faces the vertically upward upper surface and the two sides in the direction of travel. Similarly, the upstream lower branch flow path 33 faces the vertically downward lower surface and the two sides in the direction of travel.

[0043] Next, the descending flow path 34 and the ascending flow path 35 will be described. The descending flow path 34 is a part of the cooling flow path 30 in which the coolant flowing in the upstream upper branch flow path 32 flows towards the downstream battery pack. In other words, the descending flow path 34 is the flow path connecting the upstream upper branch flow path 32 and the downstream lower branch flow path 37.

[0044] The rising flow path 35 is a part of the cooling flow path 30 in which the coolant flowing in the upstream lower branch flow path 33 flows towards the downstream battery pack. In other words, the rising flow path 35 is the flow path connecting the upstream lower branch flow path 33 and the downstream upper branch flow path 36. Hereinafter, the falling flow path 34 and the rising flow path 35 will be referred to together as the connecting flow path.

[0045] The coolant flowing through the upstream upper branch flow path 32 and the coolant flowing through the upstream lower branch flow path 33 pass through the descending flow path 34 and the ascending flow path 35, respectively, thereby causing the coolant flowing through the upstream upper branch flow path 32 to flow at a lower position than the coolant flowing through the upstream lower branch flow path 33. In other words, by connecting the flow paths, the vertical positional relationship between the coolant flowing through the upstream upper branch flow path 32 and the coolant flowing through the upstream lower branch flow path 33 is reversed.

[0046] For example, the adjacent upstream and downstream battery packs have a cuboid shape, and the upstream upper branch flow path 32 and the upstream lower branch flow path 33 are respectively arranged to approach the upper and lower surfaces of the battery pack relative to the vertical direction. In this case, the descending flow path 34 is configured to allow the coolant flowing in the upstream upper branch flow path 32 to flow towards the vertical lower surface of the downstream battery pack via the descending flow path 34. In addition, the ascending flow path 35 is configured to allow the coolant flowing in the upstream lower branch flow path 33 to flow towards the vertical upper surface of the downstream battery pack via the ascending flow path 35.

[0047] The connecting flow path can be configured such that the coolant flowing on the side of the upstream battery pack flows close to the side of the downstream battery pack corresponding to that side, or it can be configured differently. For example, if the battery pack is cuboid in shape and the upstream upper branch flow path 32 is configured with the side closest to the direction of travel, the descending flow path 34 can be configured such that the coolant flowing in the upstream upper branch flow path 32 flows on the side of the downstream battery pack opposite to that side, or it can be configured such that it flows on the same side as the upstream battery pack.

[0048] Furthermore, the connecting flow path can be straight or S-shaped. For example, the descending flow path 34 can be designed to allow the coolant flowing in the upstream upper branch flow path 32 to flow obliquely downward in the vertical direction, or it can be designed to flow downward in the vertical direction. Similarly, the ascending flow path 35 can be designed to allow the coolant flowing in the upstream lower branch flow path 33 to flow obliquely upward in the vertical direction, or it can be designed to flow upward in the vertical direction.

[0049] The descending flow path 34 may not be designed to allow the coolant to descend. For example, if the upstream battery pack is positioned lower than the downstream battery pack, the descending flow path 34 can be designed to allow the coolant to rise. Similarly, the ascending flow path 35 may not be designed to allow the coolant to rise. For example, if the upstream battery pack is positioned higher than the downstream battery pack, the ascending flow path 35 can be designed to allow the coolant to descend.

[0050] The descending flow path 34 and the ascending flow path 35 are independent. In other words, the descending flow path 34 and the ascending flow path 35 are designed so that the coolant flowing in each other flows independently without intersecting. When the descending flow path 34 and the ascending flow path 35 are configured to cross each other, the flow paths are connected in a way that prevents the flow paths from contacting each other.

[0051] For example, imagine guiding coolant flowing vertically upwards in an upstream battery pack to flow vertically downwards in a downstream battery pack, and vice versa, guiding coolant flowing vertically downwards in an upstream battery pack to flow vertically upwards in a downstream battery pack. When the connecting flow paths are configured in a straight line, the descending flow path 34 and the ascending flow path 35 may come into contact at their intersection. To avoid this, either the descending flow path 34 or the ascending flow path 35 can be configured to be curved relative to the direction of travel at the intersection. Alternatively, the descending flow path 34 and the ascending flow path 35 can be configured to be curved in opposite directions at their intersection.

[0052] exist Figure 1In the design, the descending flow path 34 is straight, allowing the coolant flowing in the upstream upper branch flow path 32 to flow obliquely downwards in the vertical direction within the descending flow path 34, and to flow onto the lower vertical surface of the downstream battery pack. Similarly, the ascending flow path 35 is straight, allowing the coolant flowing in the upstream lower branch flow path 33 to flow obliquely upwards in the vertical direction within the ascending flow path 35, and to flow onto the upper vertical surface of the downstream battery pack. To avoid mid-path contact, the descending flow path 34 and the ascending flow path 35 are designed such that at least one or both of the connecting flow paths are curved in the Y-axis direction.

[0053] Next, the downstream upper branch flow path 36 and the downstream lower branch flow path 37 will be described. The downstream upper branch flow path 36 and the downstream lower branch flow path 37 are flow paths used for cooling the downstream battery pack. Hereafter, the downstream upper branch flow path 36 and the downstream lower branch flow path 37 will be collectively referred to as the downstream branch flow path. Furthermore, descriptions that overlap with the upstream branch flow path will be omitted where appropriate.

[0054] The downstream upper branch flow path 36 allows coolant flowing in the upstream lower branch flow path 33 and the rising flow path 35 to flow. In other words, the upstream lower branch flow path 33, the rising flow path 35, and the downstream upper branch flow path 36 constitute a flow path. Similarly, the downstream lower branch flow path 37 allows coolant flowing in the upstream upper branch flow path 32 and the descending flow path 34 to flow. In other words, the upstream upper branch flow path 32, the descending flow path 34, and the downstream lower branch flow path 37 constitute a flow path. In other words, the upstream upper branch flow path 32, the descending flow path 34, and the downstream lower branch flow path 37 constitute a first branch flow path, and the upstream lower branch flow path 33, the rising flow path 35, and the downstream upper branch flow path 36 constitute a second branch flow path.

[0055] The downstream branch flow path is configured along the battery housing 2, thereby cooling the downstream battery pack. Specifically, the downstream branch flow path is configured close to a surface in the battery housing 2 that houses the downstream battery pack, formed of a material with high thermal conductivity. Here, the downstream branch flow path can be in contact with this surface of the battery housing 2, or it can be configured to be isolated from the battery housing 2 with a small gap.

[0056] The downstream upper branch flow path 36 cools the downstream battery pack from a higher position relative to the downstream lower branch flow path 37. Therefore, the downstream upper branch flow path 36 is positioned higher than the downstream lower branch flow path 37. Figure 1 In the middle section, the downstream upper branch flow path 36 is disposed on the vertical upper surface of the battery casing 2b, and cools the downstream battery pack from the upper surface. In addition, the downstream lower branch flow path 37 is disposed on the vertical lower surface of the battery casing 2b, and cools the downstream battery pack from the lower surface.

[0057] In the downstream battery pack, the location of the downstream upper branch flow path 36 can be the same as or different from the location of the upstream lower branch flow path 33 in the upstream battery pack. Similarly, in the downstream battery pack, the location of the downstream lower branch flow path 37 can be the same as or different from the location of the upstream upper branch flow path 32 in the upstream battery pack.

[0058] Finally, the confluence point 38 will be explained. The confluence point 38 is the location in the cooling flow path 30 where the upper downstream branch flow path 36 and the lower downstream branch flow path 37 merge to form a single flow path. The confluence point 38 is further positioned downstream of the downstream battery pack, specifically at the suction port side of the coolant pump.

[0059] The merging point 38 may not be located lower than the downstream upper branch flow path 36. Alternatively, the merging point 38 may not be located higher than the downstream lower branch flow path 37. That is, the merging point 38 and the downstream upper branch flow path 36 may be at the same height. Or, the merging point 38 and the downstream lower branch flow path 37 may be at the same height. The merging point 38 may have a T-shape or a Y-shape. Figure 1 In the middle, the merging point 38 has a T-shape, and the downstream upper branch flow path 36 and the downstream lower branch flow path 37 merge at a position that is lower than the downstream upper branch flow path 36 and higher than the downstream lower branch flow path 37.

[0060] In this way, in the battery cooling device 3 disclosed herein, in the upstream battery pack, the cooling position provided by the upstream upper branch flow path 32 is designed to be higher than the cooling position provided by the upstream lower branch flow path 33, while in the downstream battery pack, the cooling position provided by the downstream lower branch flow path 37 is designed to be lower than the cooling position provided by the downstream upper branch flow path 36. In other words, in the upstream battery pack, the first branch flow path (upstream upper branch flow path 32) cools the upstream battery pack at a position higher than the second branch flow path (upstream lower branch flow path 33). Furthermore, in the downstream battery pack, the first branch flow path (downstream lower branch flow path 37) cools the downstream battery pack at a position lower than the second branch flow path (downstream upper branch flow path 36). The vertical positional relationship between the first and second branch flow paths is interchanged via connecting flow paths, namely, the descending flow path 34 and the ascending flow path 35.

[0061] use Figure 1 and Figure 2 The effects of the battery cooling device 3 disclosed herein will be explained. Figure 2 This diagram illustrates an example of a conventional battery cooling device. Figure 1 The difference is, Figure 2The battery cooling device shown merges the coolant into a cooling flow path as it flows from the upstream battery pack to the downstream battery pack, and then splits the coolant again into two directions, one upstream and one downstream, when cooling the downstream battery pack. Figure 2 Other structures of the battery cooling device shown are similar to Figure 1 Same. After that, for Figure 2 The conventional battery cooling devices shown have the same structure as the battery cooling device 3 involved in this disclosure, and will be described using the same names.

[0062] exist Figure 2 In a scenario where the coolant pump (not shown) operates with constant ejection pressure control, the pressure of the coolant flowing in the upstream upper branch flow path and the upstream lower branch flow path in the upstream battery pack reaches similar values. By branching the upstream upper branch flow path to a higher position relative to the upstream lower branch flow path, the flow velocity of the coolant flowing in the upstream lower branch flow path becomes faster than the flow velocity of the coolant flowing in the upstream upper branch flow path. Therefore, the flow rate of the coolant flowing in the upstream lower branch flow path is greater than the flow rate of the coolant flowing in the upstream upper branch flow path.

[0063] Figure 2 The battery cooling device involved merges the cooling flow path between the upstream and downstream battery packs into one before splitting the flow. Therefore, similar to the upstream side, the flow rate of the coolant flowing in the downstream lower branch flow path is greater than the flow rate of the coolant flowing in the downstream upper branch flow path.

[0064] If the cooling flow rate of the upper branch flow path is less than that of the lower branch flow path, the heat dissipation effect of the upper branch flow path will be lower than that of the lower branch flow path, thus causing temperature unevenness within the single cell. In conventional structures, the heat dissipation effect of the upper branch flow path is lower than that of the lower branch flow path, both upstream and downstream. Furthermore, the difference in cooling flow rate results in a greater pressure loss from the lower branch flow path than from the upper branch flow path, leading to a difference in path pressure drop between the upper and lower branch flow paths.

[0065] exist Figure 2 In the diagram, the thickness of the arrows along the upstream and downstream branch flow paths indicates the amount of coolant flow, while the thickness of the arrows extending up and down along the battery cells (single cells) indicates the strength of the heat dissipation effect.

[0066] on the other hand, Figure 1The battery cooling device 3 involved interchanges the vertical positions of the cooling positions of the first cooling flow path and the second cooling flow path by connecting the flow paths. This reduces the difference in flow velocity and the deviation in cooling flow rate between the downstream upper branch flow path 36 and the downstream lower branch flow path 37 in the downstream battery pack. This also suppresses the uneven cooling performance between the downstream upper branch flow path 36 and the downstream lower branch flow path 37, and suppresses temperature unevenness within individual cells. Furthermore, by improving the flow velocity difference, the difference in path pressure loss caused by the first and second cooling flow paths can also be suppressed.

[0067] Furthermore, the battery cooling device 3 disclosed herein can improve battery cooling performance. By providing independent descending flow path 34 and ascending flow path 35, the battery cooling device 3 has an increased surface area compared to the connected flow path in conventional battery cooling devices, thereby improving heat dissipation from the cooling flow path. As a result, the temperature of the coolant flowing through the cooling flow path decreases, thus improving the cooling performance of the downstream battery pack.

[0068] Furthermore, the battery cooling device 3 of this disclosure enables miniaturization of the mounting space for the battery system 1. In conventional battery cooling devices, the connection flow paths between the upstream and downstream battery packs cause the upstream branch flow paths to merge and then branch off to the downstream branch flow paths. Therefore, conventional battery cooling devices require space for concentrating and distributing the cooling flow paths. The battery cooling device 3 of this disclosure does not require this space, thus enabling miniaturization of the mounting space for the battery system 1.

[0069] Furthermore, the battery cooling device 3 of this disclosure can reduce pressure loss. In conventional battery cooling devices, the connecting flow paths, in order to merge upstream branch flow paths and then branch again into downstream branch flow paths, contain points where pressure losses occur due to the expansion, contraction, or bending of the cooling flow paths. In the battery cooling device 3 of this disclosure, the connecting flow paths consist of independent descending flow path 34 and ascending flow path 35, thus reducing the number of pressure loss points compared to conventional technologies. Therefore, the battery cooling device 3 can reduce pressure loss.

[0070] When using the battery cooling device 3 disclosed herein, the reduction effect on pressure loss increases with the number of battery packs cooled by a single cooling flow path. A schematic diagram of a conventional battery cooling device cooling four battery packs is shown. Figure 4 This is a schematic diagram of the battery cooling device 3 disclosed herein used to cool four battery packs. Figure 5 This is a schematic diagram of the pressure loss generated by a conventional battery cooling device and the battery cooling device 3 of this disclosure.

[0071] As the number of battery packs cooled by conventional battery cooling devices increases, the flow of coolant becomes turbulent each time the cooling flow path merges and diverges at each battery pack. Consequently, the pressure loss along the entire cooling flow path increases. In contrast, when the number of battery packs cooled by the cooling flow path 30 of this disclosure increases, although the cooling flow path diverges and merges at the upstream and downstream battery packs, there is no merging and diverging between the battery packs. Therefore, as... Figure 5 As shown, when using the battery cooling device 3 of this disclosure, the effect of reducing pressure loss is further enhanced as the number of battery packs cooled by a cooling flow path increases.

[0072] This disclosure is not limited to the above-described embodiments, and appropriate modifications may be made without departing from its spirit and intent.

Claims

1. A battery cooling device having a cooling flow path that cools a plurality of battery groups from an upstream battery group to a downstream battery group, characterized by the cooling flow path including a first branch flow path and a second branch flow path for cooling the battery groups, the first branch flow path cooling the upstream battery group at a position higher than the second branch flow path and cooling the downstream battery group at a position lower than the second branch flow path.

2. The battery cooling device according to claim 1, characterized by the first branch flow path flowing obliquely downward in a gravitational direction from the upstream battery group toward the downstream battery group, and the second branch flow path flowing obliquely upward in the gravitational direction from the upstream battery group toward the downstream battery group.

3. The battery cooling device according to claim 1, characterized by the first branch flow path cooling the upstream battery group from an upper surface in the gravitational direction and cooling the downstream battery group from a lower surface in the gravitational direction, and the second branch flow path cooling the upstream battery group from the lower surface in the gravitational direction and cooling the downstream battery group from the upper surface in the gravitational direction.

4. The battery cooling device according to claim 1, characterized by the first branch flow path cooling the upstream battery group at a position higher than the second branch flow path and cooling the downstream battery group adjacent to the upstream battery group at a position lower than the second branch flow path.

5. The battery cooling device according to claim 3, characterized by at least one of the first branch flow path and the second branch flow path or both of them are bent with respect to a traveling direction of the branch flow path between the upstream battery group and the downstream battery group.

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