POWER STORAGE DEVICE

Abstract

A power storage device comprising a power storage cell having a first surface, a cooler having a second surface facing the first surface and cooling the storage cell from one side of the first surface, and a thermally conductive element attached to the second surface and in contact with the first surface. The thermally conductive element extends across the second surface in a first direction and in a second direction perpendicular to the first direction. The length of the thermally conductive element in the first direction and the length of the thermally conductive element in the second direction is 80 mm or less.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present disclosure relates to a power storage device. 2. Description of the related prior art

[0002] Electrified vehicles, such as battery-powered electric vehicles, hybrid electric vehicles, etc., are widely known. Such an electrified vehicle is powered by an electric motor using electrical energy stored in a power storage device. The power storage device comprises a module in which a multitude of power storage cells are stacked. Each power storage cell is cooled by a heat sink. A thermally conductive element is positioned between each power storage cell and the heat sink. Typically, the heat sink is coated with a thermally conductive material, and the module is then placed onto the heat sink. This causes the thermally conductive material to spread. Subsequently, the thermally conductive material is cured.

[0003] The unexamined Japanese patent application disclosure no. 2016-203050 (JP 2016-203050 A) discloses the formation of a coating film by applying a coating fluid containing a curing component to a sheet that is moving relatively and curing the applied coating fluid. In JP 2016-203050 A, one or three strips of the coating film are formed along a web transport direction. BRIEF SUMMARY OF THE INVENTION

[0004] During the curing process of the thermally conductive material, a change in its cross-linking density leads to volume shrinkage (curing shrinkage). Particularly when the thermally conductive material is continuously applied to the cooler over a long distance, stress concentration occurs at an interface (contact area) between the two end sections in the longitudinal direction of the thermally conductive material and the energy storage cells. As a result, both end sections can detach from the energy storage cells.

[0005] The present disclosure provides a power storage device capable of preventing the detachment of a heat-conducting element from a power storage cell.

[0006] According to one aspect of the present disclosure, a power storage device comprises a power storage cell comprising a first surface, a cooler comprising a second surface facing the first surface and cooling the power storage cell from one side of the first surface, and a thermally conductive element applied to the second surface and in contact with the first surface. The thermally conductive element extends on the second surface in a first direction and in a second direction perpendicular to the first direction. The length of the thermally conductive element in the first direction and the length of the thermally conductive element in the second direction is 80 mm or less.

[0007] This configuration prevents the heat-conducting element from detaching from the cooler.

[0008] Preferably, the first surface is a base surface. A plurality of the power storage cells are stacked in the first direction. The length of each of the heat-conducting elements in the first direction is equal to or less than the length of the base surface in the first direction. The length of each of the heat-conducting elements in the second direction is equal to or less than the length of the base surface in the second direction.

[0009] In this configuration, the thermally conductive elements are provided individually for each of the power storage cells, and accordingly, the effects of curing shrinkage can be reduced compared to a common thermally conductive element for the power storage cells.

[0010] Preferably, the heat-conducting element consists of urethane.

[0011] Preferably, the length of the heat-conducting element in the second direction is 12 mm.

[0012] According to the present disclosure, detachment of the heat-conducting element from the cooler can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Features, advantages and technical and industrial significance of embodiments of the invention are described below with reference to the accompanying drawings, in which the same symbols denote the same elements and in which: Fig. 1 is a top view of a power storage device; Fig. 2 is a cross-sectional view along line II-II in Fig. 1; Fig. Figure 3 is a cross-sectional view along line III-III in Fig. 2; and Fig. Figure 4 is a diagram showing the relationship between the length of a heat-conducting element in a longitudinal direction and the stress on the heat-conducting element. DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0014] An embodiment of the present disclosure is described below with reference to the drawings. In the following description, identical components are identified by the same symbols. The same applies to the designations and functions of the components. Accordingly, the detailed description is not repeated.

[0015] A power storage device, as described below, is installed in an electrified vehicle, such as a hybrid electric vehicle capable of driving with the motive power of at least one motor and an internal combustion engine, and an electrified vehicle that drives with motive power derived from electrical energy, and so on.

[0016] Fig. Figure 1 is a top view of the power storage device according to the present embodiment. Fig. 2 is a cross-sectional view along line II-II in Fig. 1. Fig. Figure 3 is a cross-sectional view along line III-III in Fig. 2. As in the Fig. As shown in Figures 1 to 3, the power storage device 1 comprises a plurality of power storage modules 100, a cooler 200 and a plurality of heat-conducting elements 300.

[0017] In this example, three power storage modules 100 are arranged at equal intervals in an X-direction (second direction). Each of the power storage modules 100 comprises a plurality of power storage cells 110. In this example, a power storage module 100 is formed by stacking eight power storage cells 110 in a Y-direction (first direction). Each of the power storage cells 110 has a base surface (first surface) 111 and two side surfaces 112, the normal direction of which is the X-direction. The base surface 111 is rectangular. A transverse direction of the base surface 111 is the Y-direction, and a longitudinal direction of it is the X-direction, which is perpendicular to the Y-direction.

[0018] The cooler 200 cools each of the power storage modules 100. More precisely, the cooler 200 cools each of the power storage cells 110. More precisely, the cooler 200 cools each of the power storage cells 110 from the bottom surface 111. The cooler 200 cools each of the power storage cells 110 from the side of the bottom surface 111 via each of the heat-conducting elements 300, which will be described later.

[0019] As in Fig. As shown in Figure 2, the cooler 200 has upper surfaces (secondary surfaces) 211. The upper surfaces 211 face the bottom surfaces 111 of the power storage cells 110. The cooler 200 further comprises a plurality of channel-forming sections 210 and one channel-forming section 220. Note that in this example, the upper surfaces 211 are the uppermost surfaces of the channel-forming sections 210.

[0020] Each of the channel-forming sections 210 is located directly above the channel-forming section 220. Each of the channel-forming sections 210 extends in the Y-direction. In this example, three channel-forming sections 210 are arranged at equal intervals in the X-direction. Antifreeze flows in each of the channel-forming sections 210 (i.e., in the channel). In this example, a long-life coolant (LLC) is used as the antifreeze. Air flows in the channel-forming section 220. The cooler 200 cools each of the power storage cells 110 with the long-life coolant and the air.

[0021] The thermally conductive elements 300 are arranged between the cooler 200 and the power storage cells 110. In this example, three thermally conductive elements 300 are arranged between the channel-forming section 210 and the power storage cell 110. Note that the number of thermally conductive elements 300 is not limited to this.

[0022] The thermally conductive elements 300 are attached to the uppermost surfaces 211 of the cooler 200. The thermally conductive elements 300 are in contact with the bottom surfaces 111 of the power storage cells 110. In this example, three thermally conductive elements 300 are in contact with the bottom surface 111 of a power storage cell 110 ( Fig. 3) In this example, the thermally conductive elements 300 are made of urethane (especially manufactured by DuPont Corporation).

[0023] The thermally conductive elements 300 are manufactured using the following process. After a liquid thermally conductive material (e.g., gel) has been applied to the uppermost surface 211 with gaps, the power storage module 100 is placed on the cooler 200. The weight of the power storage module 100 distributes the thermally conductive material in the X and Y directions. The thermally conductive material is then cured. This process creates solid thermally conductive elements 300.

[0024] Each of the thermally conductive elements 300 has a cylindrical shape. Each of the thermally conductive elements 300 has a thin thickness that also extends in the XY plane. The thermally conductive elements 300 extend on the uppermost surface 211 in the X and Y directions. Due to the coating and contact with the bottom surfaces 111, the thermally conductive elements 300 extend in the Y direction and in the X direction, which runs perpendicular to the Y direction. In this example, the thermally conductive elements 300 have the same length in the X direction and in the Y direction.

[0025] As in Fig. As shown in Figure 3, the diameter of a base surface of each of the heat-conducting elements 300 is given by φ. The length of the base surface 111 of the power storage cell 110 in the Y-direction is given by D. Similarly, the length of the base surfaces 111 in the X-direction is given by W (> D). Note that φ denotes the diameter, and accordingly, the value of φ is the length of the heat-conducting element 300 in both the X-direction and the Y-direction.

[0026] As in Fig. As shown in Figure 3, in this example, viewed from the base surface 111 of the power storage cell 110, each of the heat-conducting elements 300 is attached to the cooler 200 such that each heat-conducting element 300 does not protrude beyond the base surface 111. Accordingly, the value of φ is equal to or less than the value of D. That is, the length (φ) of the heat-conducting elements 300 in the Y-direction is equal to or less than the length (D) of the base surfaces 111 of the power storage cells 110 in the Y-direction. It should be noted that the value of W is greater than the value of D, and accordingly, the length (φ) of each of the heat-conducting elements 300 in the X-direction is equal to or less than the length (W) of the base surfaces 111 in the X-direction.

[0027] More precisely, in this example, focusing on a power storage cell 110, three thermally conductive elements 300 are arranged in the X direction, and accordingly, the value of 3φ is smaller than the value of W. In one example, the value of D is 40 mm. In another example, the value of φ is 12 mm. This is not a limitation. The value of φ can be adjusted accordingly under the conditions described below. For example, by setting the value of φ to 40 mm, the contact area between the thermally conductive element 300, the cooler 200, and the power storage cell 110 can be increased.

[0028] Note that in this example, the thermally conductive element 300 is circular when viewed from the base surface 111, but is not restricted to this shape. The shape of the thermally conductive element 300 can be essentially rectangular when viewed from the base surface 111. The length of the thermally conductive element 300 in the X direction and its length in the Y direction need not be equal. Furthermore, each of the thermally conductive elements 300 can protrude from a base surface 111 when viewed from it. For example, a configuration can be made in which each of the thermally conductive elements 300 is in contact with several power storage cells 110.

[0029] Fig. Figure 4 is a diagram showing the relationship between the longitudinal length of the heat-conducting element and the stress on the heat-conducting element. Each of the ten values ​​in Fig. 4 assumes that the length (width) of the heat-conducting element in the transverse direction is 12 mm. In Fig. 4. The longitudinal length of the thermally conductive element is specified as L (mm). The thermally conductive element is made of urethane, manufactured by DuPont Corporation, and is identical to that of the 300 series thermally conductive elements. The ambient temperature during coating is 25°C.

[0030] The longer the longitudinal length of the thermally conductive material coating, the greater the volume of the thermally conductive material. Consequently, the volumetric shrinkage (curing shrinkage) of the thermally conductive material during curing is also greater. This, in turn, increases the stress caused by curing shrinkage. Therefore, if the longitudinal length of the thermally conductive material coating is adjusted so that the stress generated by curing shrinkage is equal to or less than the bond strength at the interface (contact area) between the thermally conductive material and the energy storage cell, the thermally conductive element can be prevented from detaching from the energy storage cell.

[0031] As in Fig. As shown in Figure 4, the stress on the thermally conductive element is less than 1.0 MPa when the value of L is 20 mm, 40 mm, 60 mm, and 80 mm, which corresponds to the bond strength at the interface between the thermally conductive element and the power storage cell. Conversely, the stress on the thermally conductive element is greater than 1.0 MPa when the value of L is 100 mm, 200 mm, 400 mm, 600 mm, 800 mm, and 1000 mm.

[0032] If the voltage in the thermally conductive element exceeds 1.0 MPa, the thermally conductive element detaches from the power storage cell. Accordingly, the thermally conductive element can be prevented from detaching from the power storage cell as long as the value of L is set to 80 mm or less.

[0033] As described above, in the power storage device 1 of this example, the detachment of the heat-conducting elements 300 from the power storage cells 110 (base surfaces 111) can be suppressed by setting each of the lengths of the heat-conducting element 300 in the X-direction and in the Y-direction to 80 mm or less. In the example above, it is sufficient to adjust the length of the heat-conducting elements 300 in the X-direction and in the Y-direction to 80 mm or less. Fig. 3. Set the value of φ shown to 80 mm or less.

[0034] The present disclosure is not limited to the above example, and the thermally conductive element 300 can be continuously applied to the cooler 200 by moving a nozzle, which dispenses the thermally conductive element 300 onto the cooler 200, relative to the cooler 200. For example, a nozzle can be used in which the length of the thermally conductive element 300 in a width direction (X-direction) is 12 mm, as shown in Fig. Figure 4 shows that in this case, too, the exit of the heat-conducting material from the nozzles can be controlled so that the length of the heat-conducting elements is 80 mm or less in the Y direction. Summaries (1) As described above, the power storage device 1 comprises the power storage cells 110 with base surfaces 111. The power storage device 1 has upper surfaces 211 facing the base surfaces 111 and includes the cooler 200, which cools the power storage cells 110 from the side of the base surfaces 111. The power storage device 1 includes the heat-conducting elements 300, which are formed by being applied to the upper surfaces 211 and are in contact with the base surfaces 111. The heat-conducting elements 300 extend in the Y direction and in the X direction, which is perpendicular to the Y direction. The length of the heat-conducting elements 300 in the Y direction and their length in the X direction is 80 mm or less. This arrangement prevents the heat-conducting elements 300 from detaching from the power storage cells 110. (2) The power storage cells 110 are stacked in the Y direction. The length of each of the thermally conductive elements 300 in the Y direction is equal to or less than the length of the base surface 111 in the Y direction. The length of each of the thermally conductive elements 300 in the X direction is equal to or less than the length of the base surface 111 in the X direction. According to such a configuration, the thermally conductive elements 300 are provided individually for each of the power storage cells 110, and accordingly, the effects of curing shrinkage can be reduced compared to the case where one thermally conductive element is shared by several power storage cells 110. (3) The heat-conducting elements 300 are made of urethane. (4) The length of the heat-conducting elements 300 in the X direction is 12 mm. (5) The power storage device 1 comprises several thermally conductive elements 300, each of which is in contact with the same base surface 111. The thermally conductive elements 300 are spaced apart from each other in the X direction. According to such a configuration, the power storage cells 110 can be cooled more efficiently than if only one thermally conductive element 300 is in contact with a base surface 111. Changes

[0035] The length of the heat-conducting elements 300 in the X-direction and their length in the Y-direction do not have to be the same. The heat-conducting elements 300 can have a transverse direction in the X-direction and a longitudinal direction in the Y-direction. That is, the heat-conducting elements 300 can extend further in the Y-direction. In other words, the heat-conducting elements 300 can extend further in the Y-direction than in the X-direction. In this case, it is sufficient if the length of the heat-conducting elements 300 in the longitudinal direction (Y-direction) in the XY top view is 80 mm or less.

[0036] Conversely, the longitudinal direction of the heat-conducting elements 300 can be the X-direction and the transverse direction the Y-direction. That is, the heat-conducting elements 300 can extend in the X-direction. In other words, the heat-conducting elements 300 can extend further in the X-direction than in the Y-direction. In this case, it is sufficient if the length of the heat-conducting elements 300 in the X-direction, as viewed from the XY plane, is 80 mm or less.

[0037] The 300 heat-conducting elements can be arranged in a state inclined relative to the X-axis and the Y-axis. Even in this case, a longitudinal length of 80 mm or less is sufficient.

[0038] The above description is an example of a configuration in which the heat-conducting elements 300 are brought into contact with the bottom surfaces 111 of the power storage cells 110, and the power storage cells 110 are cooled from the side of the bottom surface 111 by the cooler 200, but this is not limiting. For example, the power storage device 1 can be configured such that the cooler cools the side surfaces 112 ( Fig. 2) the power storage cells 110 are cooled via the heat-conducting elements.

[0039] The embodiment disclosed herein should in every respect be regarded as illustrative and not as limiting. The scope of this disclosure is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2016-203050 A

[0003]

Claims

[1] Power storage device with: a power storage cell that has a first surface; a cooler that has a second surface facing the first surface and that cools the power storage cell from one side of the first surface; and a heat-conducting element that is applied to the second surface and is in contact with the first surface, wherein the heat-conducting element spreads on the second surface in a first direction and in a second direction that is perpendicular to the first direction, and The length of the heat-conducting element in the first direction and the length of the heat-conducting element in the second direction are 80 mm or less. [2] Power storage device according to claim 1, wherein: the first area is a ground surface; a large number of the power storage cells are stacked in the first direction; the length of each of the heat-conducting elements in the first direction is equal to or less than a length of the floor area in the first direction; and the length of each of the heat-conducting elements in the second direction is equal to or less than the length of the floor area in the second direction. [3] Power storage device according to claim 1, wherein the heat-conducting element is made of urethane. [4] Power storage device according to claim 1, wherein the length of the heat-conducting element in the second direction is 12 mm.

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