Battery pack

Abstract

The utility model provides a kind of battery pack that can more effectively uniformly cool multiple battery units.Battery pack has: battery stack, comprising multiple battery units;And chamber, for distributing refrigerant to multiple battery units, chamber has the partition that has multiple air vents, partition separates chamber into inflow side of chamber and battery stack side, the shape of partition is convex in the direction of inflow of chamber.

Description

Technical Field

[0001] This disclosure relates to a battery pack having a mechanism for uniformly cooling multiple battery cells. Background Technology

[0002] Patent Document 1 discloses a battery pack having a cooling structure capable of uniformly cooling the entire battery module. The battery pack includes a mechanism for uniformizing the flow rate of the refrigerant. By uniformizing the flow rate of the refrigerant, the entire battery module can be cooled uniformly.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2007-172982 If the cooling of multiple battery cells in a battery pack is uneven, the battery cells are prone to deterioration due to overheating or overcharging. Utility Model Content

[0004] One object of this disclosure is to provide a battery pack for more efficient uniform cooling of multiple battery cells.

[0005] The battery pack of the first type is mounted on a vehicle and includes: a battery stack comprising multiple battery cells; and a chamber for distributing refrigerant to the multiple battery cells, the chamber having a partition with multiple vents, the partition dividing the chamber into an inlet side and a battery stack side. The shape of the partition is convex in the direction of the inlet of the chamber.

[0006] The battery pack of the second type is in the first type, wherein the separator has an i-th portion and an i+1-th portion located further away from the chamber than the i-th portion, the plurality of vents including an i-th vent contained in the i-th portion and an i+1-th vent contained in the i+1-th portion, the area of ​​the i-th vent being smaller than the area of ​​the i+1-th vent.

[0007] The battery pack of the third type is the same as that of the first type, in which the area of ​​each of the plurality of vents is configured to be smaller as it gets closer to the inlet of the chamber.

[0008] The fourth type of battery pack is in the first type, wherein the separator has an i-th portion and an i+1-th portion located further away from the chamber than the i-th portion, the plurality of vents including an i-th vent contained in the i-th portion and an i+1-th vent contained in the i+1-th portion, the distribution of the i-th vents being more sparse than that of the i+1-th vents.

[0009] The fifth type of battery pack is the same as the first type, in which the plurality of vents are configured to be sparsely distributed closer to the inlet of the chamber.

[0010] When the refrigerant passes through the vents in the separator, a pressure loss occurs, resulting in a decrease in flow rate. The decrease in flow rate is more significant at locations where the flow rate was originally higher. This means that the amount of refrigerant distributed to each battery cell tends to be more uniform. As a result, the battery cells are cooled evenly. Furthermore, by making the separator convex in the direction of the chamber inlet, the refrigerant can flow more smoothly to the surrounding areas, thus achieving a more significant effect of flow rate uniformity. In other words, the effect of uniformly cooling multiple battery cells is more pronounced. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a battery pack mounted on a vehicle.

[0012] Figure 2 This is a schematic diagram illustrating an example of a battery pack cooling mechanism.

[0013] Figure 3 This is a schematic diagram illustrating another example of a battery pack cooling mechanism.

[0014] Figure 4 This is a schematic diagram illustrating an example of the configuration of a vent.

[0015] Figures 5A to 5C This is a schematic diagram illustrating another possible configuration of the vent.

[0016] Figure 6 This is a schematic diagram illustrating the relationship between the location of the chamber inlet and the shape of the partition. Detailed Implementation

[0017] Embodiments of this disclosure are described with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of a battery pack 10 mounted on vehicle 1. The battery pack 10 is used as a power source for electric vehicles such as BEVs, PEVs, and HEVs. In the diagram, the X direction indicates the direction of travel of vehicle 1. The Y direction indicates the left direction when viewing vehicle 1 from above. The Z direction indicates the upward direction of vehicle 1. These directions are provided for illustrative purposes and are not intended to limit the implementation method. For example, in… Figure 1 In the present invention, the battery cells 30, described later, are stacked along the Y direction. However, the actual loading direction is not limited to the Y direction; for example, it can also be the X direction.

[0019] The battery pack 10 includes one or more battery stacks 20 (hereinafter referred to as battery stacks 20). The battery stacks 20 are constructed by stacking multiple battery cells 30 (also referred to as single cells). The battery cells 30 are rechargeable secondary batteries, such as lithium-ion secondary batteries. Additionally, the battery pack 10 typically has a casing (so-called battery housing) covering the battery stacks 20. The battery housing (not shown) is made of aluminum alloy or steel and functions to protect the battery cells 30 from external loads. The vehicle 1 is driven by rotating a motor using the electrical energy stored in the battery pack 10 (more specifically, the battery cells 30).

[0020] Battery cell 30 generates heat during charging or discharging. If this heat is not properly dissipated, the temperature of battery cell 30 will rise. Battery cell 30 deteriorates more rapidly when charged and discharged at high temperatures. Specifically, the increased temperature makes unwanted chemical reactions within battery cell 30 more active, resulting in reduced storage capacity or decreased charging efficiency.

[0021] To prevent the temperature of the battery cells 30 from rising, the battery pack 10 has a cooling mechanism. The cooling mechanism removes heat from the battery cells 30 by using a refrigerant that flows through them. As a result, the battery cells 30 can be kept at a low temperature. Air refrigerant or liquid refrigerant, etc., can be used as the refrigerant. To accurately supply the refrigerant to the battery cells 30, channels for the refrigerant to pass through are provided between each battery cell 30.

[0022] When the amount of refrigerant flowing between each battery cell 30 differs, the cooling degree of each battery cell 30 varies. As a result, the temperature of each battery cell 30 deviates. This temperature deviation leads to a deviation in charging efficiency. That is, the battery cell 30 that is sufficiently cooled charges faster, while the battery cell 30 that is not sufficiently cooled charges slower.

[0023] Consider the scenario where a battery stack 20 containing battery cells 30 with varying charging speeds is being charged. Fully charging the slower-charging battery cells 30 would mean overcharging the faster-charging cells 30, which would accelerate their degradation. Conversely, to prevent overcharging, if the faster-charging battery cells 30 are stopped charging once fully charged, the slower-charging battery cells 30 would be used before reaching full charge. In other words, the overall energy storage capacity of the battery stack 20 cannot be efficiently utilized. To keep the temperature of each battery cell 30 within the allowable range, enhanced cooling is necessary. To cool the hottest battery cell 30 to the allowable temperature, measures such as increasing the speed of the blower that flows the refrigerant are required. However, high-speed blower rotation causes noise and vibration, potentially compromising the comfort of the vehicle 1. Furthermore, using sound-absorbing or vibration-absorbing materials as noise or vibration countermeasures increases cost and weight. Moreover, intensifying the overall cooling of the battery stack 20 can lead to over-cooling of the already adequately cooled battery cells 30. This is undesirable from an energy efficiency perspective.

[0024] As mentioned above, temperature differences among the individual battery cells 30 within the battery stack 20 can cause various problems. Therefore, ensuring uniform cooling of each battery cell 30 is essential for achieving efficient utilization and extending the lifespan of the battery pack 10. Consequently, it is necessary to maintain a uniform amount of coolant distributed to each battery cell 30.

[0025] One of the factors determining the amount of refrigerant allocated to each battery cell 30 is the pressure (static pressure) difference between the inlet and outlet of the channel between the battery cells 30. When the pressure distribution at the inlet of the channel between the battery cells is uneven, the cooling of each battery cell 30 will also become uneven. Therefore, by making the pressure distribution at the inlet of the channel between the battery cells more uniform, the amount of refrigerant allocated to each battery cell 30 can also be made more uniform. Here, since the refrigerant flow rate corresponds to the pressure, uniformizing the refrigerant pressure distribution also corresponds to uniformizing the refrigerant flow rate.

[0026] Figure 2 This is a schematic diagram illustrating an example of the cooling mechanism of the battery pack 10. To eliminate uneven velocity distribution at the channel inlet, the battery pack 10 is provided with a chamber 40 connected to the channel inlet between battery cells 30. The chamber 40 is a space for distributing refrigerant to each battery cell 30, and its shape is narrower at the chamber inlet 41 and wider on the battery stack 20 side. The refrigerant flows into the chamber 40 through a conduit and diffuses within the chamber 40 toward the battery stack 20. During this process, the refrigerant velocity within the chamber 40 is higher at the front of the chamber inlet 41 and lowers further away from the front of the chamber inlet 41. In other words, the uneven velocity distribution cannot be eliminated by the chamber 40 alone.

[0027] To ensure a uniform flow velocity distribution at the inlet of the channel between battery cells, chamber 40 is equipped with a partition 50. The partition 50 divides chamber 40 into a chamber inlet 41 side and a battery stack 20 side. The partition 50 has multiple vents 51. The partition 50 can be made of metal, for example. The shapes of the multiple vents 51 can be, for example, slit-like, circular, etc. For example, a perforated metal sheet (i.e., a sheet of steel or aluminum with numerous holes) used in industrial applications can function as a partition 50 with vents 51.

[0028] The refrigerant flows to the battery cell 30 through the vent 51 of the separator 50. When passing through the vent 51, the refrigerant experiences a greater pressure loss in areas with higher flow velocities, resulting in a significant decrease in flow velocity after passing through. Conversely, in areas with lower flow velocities, the pressure loss is relatively smaller, leading to a less significant decrease in flow velocity. As a result, the refrigerant velocity (pressure) distribution tends to be more uniform after passing through the vent 51.

[0029] exist Figure 2 In this example, the baffle 50 extends in a straight line from one side wall of the chamber 40 to the other side wall. To further enhance the effect of uniform flow velocity distribution, the baffle 50 is designed as follows: Figure 3 The shape shown is valid. Figure 3 In this example, the baffle 50 is convex in the direction toward the chamber inlet 41. Alternatively, the baffle 50 can be considered as a curved shape that bulges toward the chamber inlet 41. When the baffle 50 has such Figure 3 When the bending shape is shown, with Figure 2 Compared to the straight shape shown, the refrigerant can flow more smoothly along the partition 50 to the surrounding parts (the walls of the chamber 40). Therefore, when the partition 50 is curved, the flow rate can be smoother and more uniform compared to the straight shape.

[0030] By providing a baffle 50 with a vent 51 within the chamber 40, the flow rate distribution of the refrigerant flowing in the battery cell 30 tends to be uniform. This means that the amount of refrigerant distributed to each battery cell 30 also tends to be uniform. As a result, the battery cell 30 is cooled uniformly. Furthermore, by making the shape of the baffle 50 convex in the direction toward the chamber inlet 41, the refrigerant can flow more smoothly to the peripheral parts, thereby achieving a more significant flow rate uniformity effect.

[0031] Figures 4 to 5C This is a schematic diagram illustrating an example of the configuration of the vent 51. Figure 4 In this case, the shape and distribution of the vents 51 are all identical. Or, as... Figures 5A to 5C As shown, the shape of the vent 51 can also vary depending on its location. For example, the shape and distribution of the vent 51 can be changed according to the distance of the chamber 40 relative to the chamber inlet 41. In this disclosure, the partition 50 has an i-th portion and an (i+1)-th portion further away from the chamber inlet 41 than the i-th portion. The plurality of vents 51 includes an i-th vent disposed in the i-th portion and an (i+1)-th vent disposed in the (i+1)-th portion. Figures 4 to 5CIn this configuration, the portion 50a is located on the front of the chamber inlet 41. Second portions 50b are located on the left and right sides of the first portion 50a. In this case, the distances between the second portions 50b on the left and right sides of the first portion 50a and the chamber inlet 41 are equal. Furthermore, the chamber inlet 41 is located at the center of the width direction of the chamber 40.

[0032] Figures 5A to 5C In the example shown, the shape and distribution of the vent 51 differ between Part 1 50a and Part 2 50b.

[0033] exist Figure 5A In this configuration, the area of ​​the first vent 51a in part 1 50a is smaller than the area of ​​the second vent 51b in part 2 50b. Therefore, the amount of refrigerant flowing through the higher-velocity part 50a is reduced, thereby contributing to uniform cooling of the battery cell 30. Figure 5A The structure can be summarized as follows: the area of ​​the i-th vent is smaller than the area of ​​the (i+1)-th vent.

[0034] exist Figure 5B In the first part 50a, the distribution of the first vent 51a is sparser than that of the second vent 51b in the second part 50b. This reduces the amount of refrigerant flowing through the higher-velocity first part 50a, thus contributing to more uniform cooling of the battery cell 30. Figure 5B The structure can be summarized as follows: the i-th vent is configured to be sparser than the (i+1)-th vent.

[0035] exist Figure 5C In this part 50a, the area of ​​the first vent 51a is smaller than the area of ​​the second vent 51b in part 50b. Furthermore, the distribution of the first vent 51a in part 50a is also sparser than that of the second vent 51b in part 50b. That is to say, Figure 5C The structure can be regarded as Figure 5A and Figure 5B The combination of these factors results in a reduction in the amount of refrigerant flowing through section 50a, which helps to achieve uniform cooling of the battery cell 30.

[0036] Figure 6 This is a schematic diagram illustrating the relationship between the position of the chamber inlet 41 and the shape of the partition 50. The position of the chamber inlet 41 does not necessarily need to be located on the centerline of the chamber 40. Figure 6In this configuration, the chamber inlet 41 is offset to the right relative to the center of the chamber 40. Furthermore, the septum 50 is convex (i.e., bulging out on the right) in the direction towards the chamber inlet 41. Starting from the right side near the chamber inlet 41, the septum 50 is divided into three parts: part 1 50a, part 2 50b, and part 3 50c. The area of ​​the first vent 51a, the second vent 51b, and the third vent 51c corresponding to each part decreases as they approach the chamber inlet 41.

[0037] In the aforementioned example, the vent 51 has an i-th vent corresponding to a discontinuous segment such as the i-th portion of the partition 50. However, the structure of the vent 51 is not limited to this, and can also be continuously (gradually) varied without depending on the discontinuous segment. That is, it is also possible to adopt a structure in which the area of ​​the vent 51 gradually decreases closer to the chamber inlet 41, or a structure in which the vent 51 is gradually sparsely distributed closer to the chamber inlet 41.

Claims

1. A battery pack, mounted on a vehicle, characterized in that, have: A battery stack, comprising multiple battery cells; and A chamber for distributing refrigerant to the plurality of battery cells. The chamber is equipped with a partition having multiple vents. The partition divides the chamber into an inlet side and a battery stack side. The shape of the partition is convex in the direction of the inlet of the chamber.

2. The battery pack according to claim 1, characterized in that, The partition has an i-th portion and an (i+1)-th portion located further away from the chamber than the i-th portion. The plurality of vents includes the i-th vent contained in the i-th part, and the i+1-th vent contained in the (i+1)-th part. The area of ​​the i-th vent is smaller than the area of ​​the (i+1)-th vent.

3. The battery pack according to claim 1, characterized in that, The area of ​​each of the plurality of vents is configured to be smaller as it gets closer to the inlet of the chamber.

4. The battery pack according to claim 1, characterized in that, The partition has an i-th portion and an (i+1)-th portion located further away from the chamber than the i-th portion. The plurality of vents includes the i-th vent contained in the i-th part, and the i+1-th vent contained in the (i+1)-th part. The distribution of the i-th vent is sparser than that of the (i+1)-th vent.

5. The battery pack according to claim 1, characterized in that, The plurality of vents are configured to be sparsely distributed as they are closer to the inlet of the chamber.

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