Busbar module

Abstract

The busbar module is made smaller and lower profile while reducing the temperature measurement error of the battery cells using thermistors. [Solution] The busbar module 11 comprises a busbar 6 that connects the electrodes 91 of adjacent battery cells 9 in the battery 10, a case 2 that holds the busbar 6, an FPC 3 on which a thermistor 4 for detecting the temperature of the battery cells 9 is surface-mounted, and a metal heat collecting component 5 that surrounds the thermistor 4. The inside of the heat collecting component 5 and around the thermistor 4 is filled with resin. The busbar 6 and the heat collecting component 5 are spaced apart and connected by a resin part 7. The busbar body 61 and the heat collecting component 5 are positioned offset from each other in the thickness direction and the surface direction of the busbar body 61, and the resin part 7 is formed in an L shape.

Description

Technical Field

[0001] The present invention relates to a bus bar module attached to a battery cell assembly.

Background Art

[0002] As an example of a battery mounted in an electric vehicle or a hybrid vehicle, a battery cell assembly in which a plurality of battery cells are arranged in parallel and a bus bar module attached to the battery cell assembly are known.

[0003] FIG. 10 is a diagram showing a part of a conventional bus bar module (see Patent Document 1). The bus bar module in FIG. 10 is attached to a battery cell assembly. This bus bar module includes a plurality of bus bars 521, an FPC (Flexible Printed Circuit) 530, and a resin case 540 that holds these.

[0004] The bus bar 521 connects the electrodes 513 of adjacent battery cells 511 in the battery cell assembly. In the battery cell assembly, a plurality of battery cells 511 are connected in series by a plurality of bus bars 521. The bus bar 521 integrally has a rectangular plate-shaped bus bar main body portion 522 and an extension portion 523 extending from the edge of the bus bar main body portion 522. A through hole 525 is formed in the extension portion 523.

[0005] The FPC 530 has a first conductive path 531 and a second conductive path 532 formed thereon. A thermistor 526 for detecting the temperature of the battery cell 511 is connected to the first conductive path 531. The thermistor 526 is disposed in the through hole 525 of the extension portion 523. The through hole 525 is filled with resin. The second conductive path 532 is a circuit for detecting the voltage of the battery cell 511 and is connected to the bus bar 521 via a connecting portion 528. The connecting portion 528 is a metal plate separate from the bus bar 521 and is connected to the bus bar 521 and the second conductive path 532 by a method such as soldering.

[0006] In the battery equipped with the busbar module described above, the heat generated in the battery cell 511 when energized is transferred to the busbar 521 via the electrode 513. The heat transferred to the busbar 521 is conducted through the busbar 521 to the extension portion 523. The heat transferred to the extension portion 523 is then transferred to the resin filling the through hole 525. The heat transferred to the resin is then transferred to the thermistor 526. As a result, the temperature of the battery cell 511 can be measured by the thermistor 526. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 7004231 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the conventional busbar module shown in Figure 10, the thermistor 526 is integrated with the busbar 521 by resin filled in the through-hole 525, enabling a smaller and lower profile busbar module. However, the inventors of this invention have discovered a problem with the conventional busbar module shown in Figure 10: the temperature measurement error of the battery cell 511 by the thermistor 526 is large. Specifically, when energized, the busbar 521 generates heat due to contact resistance with the electrode 513, etc. Due to this energizing heat, the temperature of the busbar 521 becomes higher than the temperature of the battery cell 511, and the energizing heat temperature becomes dominant for the thermistor 526, making it impossible to perform measurements with low error.

[0009] Thermistors are used to measure the temperature of battery cells in order to detect battery life, driving performance (fuel efficiency), and smoke emission. Therefore, it is necessary to measure the battery cell temperature with as little error as possible. For example, if the thermistor outputs a temperature higher than the actual battery cell temperature, the current will be reduced, resulting in a decrease in driving performance.

[0010] Therefore, the present invention aims to reduce the temperature measurement error of battery cells by thermistors while making the busbar module smaller and lower in profile. [Means for solving the problem]

[0011] The present invention relates to a busbar module comprising: a busbar connecting electrodes of adjacent battery cells in a battery; a thermistor for detecting the temperature of the battery cells; and a metal heat collecting component formed in a frame shape and surrounding the thermistor, wherein the busbar and the heat collecting component are spaced apart and connected by a material with lower thermal conductivity than the busbar. [Effects of the Invention]

[0012] According to the present invention, it is possible to reduce the size and height of the busbar module while minimizing the temperature measurement error of the battery cell using the thermistor. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows a part of a busbar module according to one embodiment of the present invention. [Figure 2] This is a view of the busbar module from Figure 1, but from a different angle. [Figure 3] This is a side view of the busbar module (case omitted) shown in Figure 1. [Figure 4] This diagram shows the busbar, heat collection component, and resin part shown in Figure 1. [Figure 5] This figure shows a part of the case in Figure 1. [Figure 6] This figure shows a portion of the busbar module of Comparative Example 1. [Figure 7] This figure shows a portion of the busbar module of Comparative Example 2. [Figure 8] This is a diagram showing a part of the busbar module of Comparative Example 3. [Figure 9] This table shows the battery cell temperatures detected by the busbar modules of the present invention and Comparative Examples 1-3. [Figure 10]It is a diagram showing a part of a conventional bus bar module.

Embodiment for Carrying out the Invention

[0014] The “bus bar module” according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIGS. 1 and 2 are diagrams showing a part of the bus bar module 11 according to an embodiment of the present invention. FIG. 3 is a diagram of the bus bar module 11 viewed from the side with the case 2 omitted. FIG. 4 is a diagram showing the bus bar 6, the heat collecting component 5, and the resin part 7 that constitute the bus bar module 11. FIG. 5 is a diagram showing a part of the case 2 that constitutes the bus bar module 11.

[0015] The bus bar module 11 shown in FIGS. 1 and 2 is attached to the battery cell assembly 12 and constitutes the battery 10 together with the battery cell assembly 12. This battery 10 is mounted on an electric vehicle or a hybrid vehicle and used as a driving power source for the vehicle.

[0016] The battery cell assembly 12 is formed by arranging a plurality of battery cells 9 in the direction of arrow X in FIGS. 1 to 3. In FIGS. 1 and 2, two battery cells 9 in the battery cell assembly 12 are shown, and illustration of other battery cells 9 is omitted.

[0017] Each battery cell 9 has a rectangular parallelepiped cell body 90 and a pair of electrodes 91 protruding from the upper surface 90a of the cell body 90. The pair of electrodes 91 protrude from one end and the other end in the longitudinal direction (arrow Z direction in FIGS. 1 to 3) of the upper surface 90a of the cell body 90. In FIGS. 1 to 3, only the electrode 91 at one end is shown, and illustration of the electrode 91 at the other end is omitted.

[0018] The "upper surface 90a of the cell body 90" means the surface located on the upper side in the direction of arrow Y in FIGS. 1 to 3 of the cell body 90. This "upper surface 90a" is a term for convenience in explaining the present invention, and in the actual state where the battery 10 is mounted on an automobile, the "upper surface 90a" may not be located on the upper side. Thus, in this specification, for convenience in explaining the present invention, the upper side in the direction of arrow Y in FIGS. 1 to 3 is defined as "up".

[0019] As shown in FIG. 3, the electrode 91 has a stepped portion 91b formed higher than the upper surface 90a of the cell body 90 and a bolt portion 91c protruding from the stepped portion 91b.

[0020] The bus bar module 11 includes a plurality of bus bars 6, a case 2, an FPC (Flexible Printed Circuit) 3, a plurality of heat collecting components 5, and a plurality of resin parts 7.

[0021] The bus bar 6 connects the electrodes 91 of adjacent battery cells 9 in the battery cell assembly 12. In FIGS. 1 and 2, only one bus bar 6 is shown, but since three or more battery cells 9 in the battery cell assembly 12 are arranged in the direction of arrow X, a plurality of bus bars 6 are also arranged in the direction of arrow X. Also, in FIGS. 1 and 2, the illustration of the electrode 91 at the other end of each battery cell 9 is omitted, but the electrodes 91 on the non-illustrated sides are also connected by the bus bar 6. Thus, in the battery cell assembly 12, a plurality of battery cells 9 are connected in series by a plurality of bus bars 6.

[0022] Each bus bar 6 is obtained by punching a single metal plate. As shown in FIG. 4, each bus bar 6 integrally has a bus bar main body portion 61 formed in a flat plate shape, a voltage detection portion 63 extending from the edge of the bus bar main body portion 61, and a protruding portion 62 protruding from the edge of the bus bar main body portion 61.

[0023] Two bolt holes 61a are formed in the busbar body 61. The bolt portions 91c of each adjacent battery cell 9 are passed through these bolt holes 61a. The stepped portions 91b of each adjacent battery cell 9 are stacked on the lower surface of the busbar body 61. In this example, the busbar body 61 and the stepped portions 91b are welded together, but instead of welding, nuts may be fastened to the bolt portions 91c, and the busbar body 61 may be sandwiched between the nuts and the stepped portions 91b.

[0024] The voltage detection unit 63 and the protruding portion 62 protrude from the edge of the busbar body 61 in the same direction (arrow Z direction). The voltage detection unit 63 protrudes more from the edge of the busbar body 61 than the protruding portion 62. The busbar body 61, the voltage detection unit 63, and the protruding portion 62 are arranged on the same plane.

[0025] The voltage detection unit 63 is superimposed on the FPC3 and connected to the voltage detection circuit of the FPC3. A rectangular through-hole 63a is formed in the voltage detection unit 63. A circuit protection fuse 8 is incorporated into the voltage detection circuit of the FPC3, and this fuse 8 is located inside the through-hole 63a. The protruding part 62 is embedded in the resin part 7, which will be described later.

[0026] Case 2 is made of an insulating synthetic resin. Case 2 integrally includes a plurality of busbar housing sections 21 arranged in the direction of arrow X, and a connecting section 20 that connects adjacent busbar housing sections 21 to each other.

[0027] The busbar housing section 21 is the part that houses the busbars 6 described above. One busbar 6 is housed in one busbar housing section 21. As shown in Figures 1, 2, and 5, each busbar housing section 21 has a bottom plate 22 located on the lower side of the busbar body 61 and walls 23, 24, 25, and 26 surrounding the busbar body 61.

[0028] A pair of openings 22a are formed in the bottom plate 22 of the busbar housing 21. The stepped portion 91b of the electrode 91 is positioned in each opening 22a. The bolt portion 91c is then passed through the bolt hole 61a of the busbar body 61 and positioned inside the busbar housing 21.

[0029] The wall 24 of the busbar housing 21 is provided with two locking claws 27. These locking claws 27 engage with the edge of the busbar body 61 to prevent the busbar 6 from lifting up.

[0030] Notches 26a and 26b are formed in the wall 26 of the busbar housing 21. Notch 26a is for passing the voltage detection unit 63 through. Notch 26b is for passing the resin part 7 and the protruding part 62 through.

[0031] FPC3 is a well-known type in which an electrical circuit is formed on a thin, flexible base film. As shown in Figures 1 and 2, FPC3 has a main line section 31 extending in the direction of arrow X, and a plurality of branch sections 32 branching off from the main line section 31.

[0032] A thermistor 4 for detecting the temperature of the battery cell 9 is surface-mounted at the end portion 34 of each branch 32. The end portion 34 is located on the upper surface 90a of the cell body 90. A metal heat collector component 5 is superimposed on the upper surface of the end portion 34.

[0033] The heat collecting component 5 is obtained by press-forming a metal plate. As shown in Figure 4, the heat collecting component 5 integrally comprises a main body portion 51 formed in a frame shape with a rectangular through hole 51a and an upright portion 52 bent upward from the end of the main body portion 51.

[0034] The thermistor 4, surface-mounted on the upper surface of the end portion 34, is positioned within the through-hole 51a of the main body portion 51 of the heat collecting component 5. In other words, the main body portion 51 of the heat collecting component 5 surrounds the thermistor 4. The inside of the through-hole 51a and around the thermistor 4 are filled with resin 14 (see Figure 3; not shown in Figures 1 and 2). The resin 14 transfers heat from the heat collecting component 5 to the thermistor 4. The resin 14 also fixes and integrates the end portion 34 and the heat collecting component 5. The upright portion 52 of the heat collecting component 5 is embedded in the resin portion 7, which will be described later.

[0035] A fuse 8 for protecting the voltage detection circuit is surface-mounted in the intermediate section 33 of each branch section 32. A voltage detection unit 63 is superimposed on the upper surface of the intermediate section 33, and the circuit protection fuse 8 is placed in the through-hole 63a of the voltage detection unit 63. The inside of the through-hole 63a and around the fuse 8 are filled with resin 14.

[0036] The FPC3 is connected to the in-vehicle control unit. In this example, the busbar module 11 detects the voltage and temperature of each battery cell 9, and the in-vehicle control unit monitors these voltages and temperatures.

[0037] As shown in Figures 3 and 4, the busbar 6 and the heat collecting component 5 are spaced apart and connected by a resin part 7. The resin part 7 is made of a synthetic resin material with lower thermal conductivity than the busbar (which generally refers to the metal wiring plate called a "busbar," including the busbar 6 in this example). In this example, when viewed from above, the heat collecting component 5 is positioned on the extension of the protruding portion 62, and the voltage detection unit 63 and the heat collecting component 5 are aligned in the direction of arrow X. When viewed from the side, the heat collecting component 5 is positioned below the busbar 6. That is, the busbar body 61 and the heat collecting component 5 are positioned offset from each other in the thickness direction (arrow Y direction) and the surface direction (arrow Z direction) of the busbar body 61. For this reason, the resin part 7 is formed in an L shape. In addition, the protruding portion 62 of the busbar 6 and the upright portion 52 of the heat collecting component 5 are embedded in the resin part 7.

[0038] As mentioned above, the reason the heat collector 5 is positioned below the busbar 6 is to bring the heat collector 5 and the thermistor 4 at the end portion 34 closer to the upper surface 90a of the cell body 90. The closer the distance between the upper surface 90a and the thermistor 4, the more accurately the temperature of the cell body 90 can be measured. In this example, the battery cell 9 has electrodes 91 protruding from the upper surface 90a of the cell body 90, so a step is provided between the busbar 6 and the heat collector 5 as described above. However, in the case of a battery cell structure where the electrodes do not protrude, the busbar 6 and the heat collector 5 can be positioned at the same height.

[0039] As mentioned above, the busbar 6 and the heat collecting component 5 are connected and integrated by the resin part 7. In this example, the busbar 6, heat collecting component 5, and resin part 7 are integrated by insert molding. In addition to insert molding, the busbar 6, heat collecting component 5, and resin part 7 may also be integrated by bonding, press-fitting, or locking. The busbar 6 and heat collecting component 5 can perform their respective functions even if they are not integrated, but by integrating them, the busbar module 11 can be made smaller and lower profile, and the number of parts can be reduced. Furthermore, in this example, the FPC 3 and thermistor 4 are integrated with the heat collecting component 5 by resin 14, so the busbar module 11 can be made even smaller and lower profile, and the number of parts can be reduced even further. Fewer parts make it easier to assemble the busbar module 11, leading to cost reduction.

[0040] In the battery 10 of this example, the busbar 6 generates heat due to contact resistance, etc., when power is applied. In this example, the busbar 6 and the heat collecting component 5 are connected by a resin part 7 made of a resin material with a much lower thermal conductivity than metal, so that the heat generated by the busbar 6 does not affect the heat collecting component 5 and thermistor 4. Therefore, the thermistor 4 at the end portion 34 is hardly affected by the heat generated by the busbar 6 and can accurately measure the temperature of the cell body 90 by the heat transmitted from the upper surface 90a.

[0041] Figures 6-8 show comparative examples considered by the inventor of the present invention when adopting the configuration of the present invention. Figure 6 shows a part of the busbar module of Comparative Example 1, which is equipped with busbar 6A instead of busbar 6. Figure 7 shows a part of the busbar module of Comparative Example 2, which is equipped with busbar 6B instead of busbar 6. Figure 8 shows a part of the busbar module of Comparative Example 3, which is equipped with busbar 6C instead of busbar 6. The busbar modules in Figures 6-8 have the same configuration as the busbar module 11 described above, except for the busbars. Also, in Figures 6-8, the battery cell 9 has the same configuration as the battery cell 9 in Figures 1-3 described above, and constitutes the battery cell assembly 12.

[0042] The busbar 6A in Figure 6 integrally comprises a main body 61, a connecting portion 62A corresponding to a protruding portion 62, a heat collecting portion 65 that serves as a heat collecting component 5, and a connecting portion 64A that is continuous with the heat collecting portion 65 and the connecting portion 62A. That is, the busbar 6A having these parts is obtained by punching and bending a single metal plate. The heat collecting portion 65, the connecting portion 64A, and the connecting portion 62A are formed to be of equal width. The heat collecting portion 65 is formed in a frame shape with a rectangular through hole 65a. A thermistor 4 for detecting the temperature of the battery cell 9 is placed inside the through hole 65a. In addition, the inside of the through hole 65a and around the thermistor 4 are filled with resin. This comparative example 1 is similar to the conventional busbar module shown in Figure 10.

[0043] The bus bar 6B in Figure 7 has a connecting portion 62B that is narrower than the connecting portion 62A of the bus bar 6A in Figure 6, but otherwise it has the same configuration as the bus bar 6A in Figure 6. The bus bar 6C in Figure 8 has a connecting portion 64C that is narrower than the connecting portion 64A of the bus bar 6B in Figure 7, but otherwise it has the same configuration as the bus bar 6B in Figure 7.

[0044] Figure 9 is a table showing the temperature (in °C) of the battery cell 9 detected by the busbar module 11 of the present invention and the busbar modules of Comparative Examples 1 to 3. The ambient temperature at the time of detection was 25 °C, and the actual temperature of the upper surface 90a of the cell body 90 was 60 °C. In addition, the temperature of the electrode 91 of the battery cell 9 was set to 100 °C and 150 °C, and the temperature of the battery cell 9 was measured under each condition.

[0045] In these temperature measurements, if the thermistor 4 is not affected by the heat generated by the current flow in the busbar, it often detects a temperature lower than the cell temperature of 60°C due to heat dissipation to the ambient temperature. Looking at the table in Figure 9, when the electrode temperature is 100°C, Comparative Examples 1 to 3 are above 60°C, and only the present invention is slightly below 60°C. It can be said that the busbar module 11 of the present invention is able to accurately measure the temperature of the cell body 90 without being affected by the heat generated by the current flow in the busbar 6. When the electrode temperature is 150°C, Comparative Examples 1 to 3 are above 70°C, and although the present invention is also slightly above 60°C, there is a temperature measurement error of more than 10°C between Comparative Examples 1 to 3 and the present invention. Furthermore, in Comparative Examples 2 and 3, the temperature is slightly lower than in Comparative Example 1 by narrowing the width of the connecting parts 62B and 64C, and it can be said that the effect of the heat generated by the current flow in the busbar is slightly reduced, but it is nowhere near as good as the present invention.

[0046] Thus, according to the present invention, the busbar module 11 can be made smaller and lower profile while reducing the temperature measurement error of the battery cell 9 by the thermistor 4. Furthermore, since the battery 10 equipped with this busbar module 11 can accurately measure the temperature of the battery cell 9, its performance can be maximized, and fuel efficiency can be improved.

[0047] In the embodiments described above, the busbar and the heat collecting component were connected by a resin part. However, in the present invention, the connection between the busbar and the heat collecting component is not limited to a resin part; it is sufficient if the connection is made by a material with a lower thermal conductivity than the busbar.

[0048] The embodiments described above merely represent typical forms of the present invention, and the present invention is not limited to these embodiments. That is, it can be implemented with various modifications without departing from the core principles of the present invention. As long as such modifications still possess the configuration of the present invention, they are of course included within the scope of the present invention. [Explanation of Symbols]

[0049] 2 cases 3 FPC 4 Thermistor 5 Heat collection parts 6 Bass 7. Resin part 9 battery cells 10 batteries 11 Busbar Modules 12 Battery cell assemblies

Claims

1. A busbar connects the electrodes of adjacent battery cells in a battery, A thermistor for detecting the temperature of the battery cell, It comprises a metal heat collecting component formed in a frame shape and surrounding the thermistor, The busbar and the heat collecting component are spaced apart and connected by a material with lower thermal conductivity than the busbar. A busbar module characterized by the following features.

2. The flexible printed circuit board is equipped with the thermistor mentioned above, The heat collecting component is arranged on the surface of the flexible printed circuit board. The inside of the heat collecting component and the area around the thermistor are filled with resin. The busbar module according to feature 1.

3. The busbar comprises a busbar body formed in the shape of a flat plate, and a voltage detection unit extending from the edge of the busbar body and connected to the flexible printed circuit board. The busbar module according to feature 2.

4. The busbar and the heat collecting component are connected by a resin part. The aforementioned busbar has a busbar body portion formed in the shape of a flat plate, The busbar body and the heat collecting component are positioned offset from each other in the thickness direction and surface direction of the busbar body, and the resin portion is formed in an L-shape. The busbar module according to feature 1.

Images