Battery pack

Abstract

The present application addresses the problem of providing a battery pack 40 that can flexibly handle changes in specifications. The problem is solved by the battery pack 40, which is installed in a hybrid system 10, the battery pack comprising: a battery module 50 for supplying power to a motor generator 2 of the hybrid system 10; a control circuit for controlling the battery module 50; and a housing 400 for accommodating the battery module 50 and the control circuit. The battery module 50 includes a plurality of battery cells 510, and a cell case 500 accommodating the plurality of battery cells 510 and including a fixing part 500a for the housing 400. The control circuit includes a BMU 85 for monitoring and controlling the whole state of the battery module 50, and a CMU 87 for monitoring a state of each of the plurality of battery cells 510 and transmitting information to the BMU 85. The CMU 87 is attached to the cell case 500 in one battery module 50.

Description

Battery pack

[0001] The present invention relates to a battery pack mounted on a hybrid system.

[0002] Patent Document 1 discloses a battery mounting structure for use in electric vehicles and hybrid vehicles. This battery mounting structure includes a case that houses multiple battery modules for driving the vehicle, located below a floor panel of a vehicle interior. The multiple battery modules are divided into lower and upper modules. The case includes a metal lower case member, a metal middle case member, and an upper case member that covers a predetermined area of ​​the upper surface of the middle case member from above. The lower module is fixed to the bottom of the lower case member, and the middle case member is fixed to the lower case member so as to cover the lower module from above, thereby watertightly housing the lower module. The upper module is fixed in a state where it is in close contact with the upper surface of the middle case member within a predetermined area. The upper case member is formed in a container shape with an opening at its bottom, covers a predetermined area, and is fixed with the periphery of the opening in close contact with the upper surface of the middle case member, thereby watertightly housing the upper module. The lower case member is then attached to the underside of the floor panel, thereby fixing the case to the vehicle.

[0003] Patent Literature 2 discloses a battery pack device for use in, for example, an electric vehicle, which is composed of batteries stacked in multiple layers. The battery pack device includes a first battery group consisting of multiple batteries arranged on the same plane, and a second battery group consisting of multiple batteries identical to the first battery group arranged on the same plane within the battery tray, sandwiched between the first battery group and the second battery group. The battery pack includes a battery unit in which the batteries are electrically connected to each other, and a main body case that houses the battery unit. The batteries are rectangular parallelepiped and can be installed in a first position in which the height in the direction in which the second battery group overlaps the first battery group is small, and a second position in which the positions of the battery terminals in the direction in which they overlap are higher than those in the first position. This battery pack device is characterized in that a first battery of a first battery group is arranged in a second position, a hole is formed in the battery tray through which the vicinity of the terminal of the first battery passes, allowing the terminal of the first battery to come out toward the second battery group, a second battery of the second battery group near the hole is arranged in the first position, and the first battery and the second battery are electrically connected to each other by a connecting member having a fixed shape.

[0004] The battery pack housing contains the number of battery cells required to obtain a desired voltage. The status of each battery cell is monitored by a cell management unit (CMU), and the overall status of the battery module including multiple battery cells is monitored by a battery management unit (BMU). For this reason, the battery pack design requires a control circuit that corresponds to the number and layout of battery cells required to obtain the desired voltage specification, making it difficult to flexibly respond to specification changes.

[0005] The battery pack housing contains the number of battery cells required to obtain the desired voltage. These battery cells are lithium-ion batteries or nickel-metal hydride batteries. The battery cells are arranged in a roughly rectangular parallelepiped shape, with multiple battery cells arranged in the limited space within the housing. Because the battery cells generate heat due to chemical reactions during charging and discharging, it is important to efficiently dissipate the heat emitted from the battery cells housed in a sealed state within the housing.

[0006] JP 2020-001451 A JP 2006-080042 A

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a battery pack that can flexibly respond to changes in specifications and that can efficiently release heat from the battery cells to the outside.

[0008] A first aspect of the present invention is a battery pack mounted on a hybrid system, comprising: a battery module that supplies power to a motor generator of the hybrid system; a control circuit that controls the battery module; and a housing that accommodates the battery module and the control circuit, wherein the battery module has a plurality of battery cells and a cell case that accommodates the plurality of battery cells, and the control circuit has a BMU (Battery Management Unit) that monitors and controls the overall state of the battery pack, and a CMU (Cell Management Unit) that monitors the state of each of the plurality of battery cells and sends information to the BMU, and the CMU is a battery pack that is attached to the cell case in the battery module.

[0009] A second aspect of the present invention is a battery pack mounted on a hybrid system, comprising: a battery module that supplies power to a motor generator of the hybrid system; a control circuit that controls the battery module; a housing that accommodates the battery module and the control circuit; and an insulating heat-conducting member that is provided between the battery module and the housing.

[0010] According to the present invention, it is possible to provide a battery pack that can flexibly respond to changes in specifications and that can efficiently release heat from the battery cells to the outside.

[0011] 1 is a block diagram showing a hybrid system. FIG. 1 is an external perspective view illustrating a battery pack according to the present embodiment. FIG. 2 is a partially exploded perspective view illustrating a battery pack according to the present embodiment. FIG. 3 is a partially exploded perspective view illustrating a battery module. FIG. 4 is a schematic perspective view illustrating a connection of a plurality of battery cells. FIG. 5 is a schematic perspective view illustrating an arrangement of a plurality of battery modules. FIG. 6 is a plan view illustrating an arrangement of a plurality of battery modules. FIG. 7 is a plan view illustrating an individual cell case. FIG. 8 is a plan view illustrating an example arrangement of individual cell cases (part 1). FIG. 9 is a perspective view illustrating an example arrangement of individual cell cases (part 2). FIG. 10 is a partially exploded perspective view illustrating another battery pack according to the present embodiment. FIG. 11 is a schematic cross-sectional view illustrating another battery pack according to the present embodiment. FIG. 12 is a perspective view illustrating a ceiling surface of a housing cover.

[0012] Preferred embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are preferred specific examples of the present invention, and therefore various technically preferable limitations are applied. However, the scope of the present invention is not limited to these aspects unless otherwise specified in the following description to the effect that the present invention is limited. Furthermore, in each drawing, similar components are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0013] (Hybrid System) Fig. 1 is a block diagram showing a hybrid system. A battery pack 40 to which a housing according to this embodiment is applied is mounted in a hybrid system 10 shown in Fig. 1. The hybrid system 10 includes an engine 1, a motor generator 2, and the battery pack 40. The hybrid system 10 according to this embodiment further includes a DC / DC converter 70. The engine 1 is an internal combustion engine, such as a diesel engine. The engine 1 is mounted, for example, in a vehicle (such as a passenger car or a small mobile object) or in industrial machinery such as construction machinery or agricultural machinery.

[0014] The engine 1 is, for example, a multi-cylinder diesel engine such as a turbocharged, high-output, three-cylinder or four-cylinder engine. However, the engine 1 is not limited to a diesel engine. The engine 1 has an ECU (Engine Control Unit) 150. The ECU 150 controls the operation of the engine 1 and also controls the motor generator 2 and the DC / DC converter 70 by communicating with them via, for example, a CAN (Controller Area Network).

[0015] The motor generator 2 operates using power supplied from the battery pack 40 to support the engine 1 when power is needed, such as when starting or accelerating the vehicle or the like equipped with the hybrid system 10. The motor generator 2 also uses regenerative braking or the like to convert the kinetic energy of the industrial machinery or the like equipped with the hybrid system 10 into electrical energy to generate electricity.

[0016] The battery pack 40 includes a battery module 50, a positive contactor 75, a negative contactor 76, a current detector 65, a temperature detector 67, a battery management unit (BMU) 85, and a cell management unit (CMU) 87. The battery module 50 is provided as a drive power source for the motor generator 2 and supplies power to the motor generator 2. The battery module 50 includes at least one battery cell 510. In the hybrid system 10 shown in FIG. 1 , the battery module 50 includes the number of battery cells 510 necessary to obtain a voltage of, for example, 48 V. The battery cell 510 may be, for example, a lithium-ion battery (LiB). However, the battery cell 510 in this embodiment is not limited to a lithium-ion battery. The battery module 50 includes a positive (+) terminal 51 and a negative (-) terminal 52.

[0017] The positive contactor 75 is provided in an electrical circuit between the positive terminal 51 of the battery module 50 and the motor generator 2. Specifically, as shown in FIG. 1 , the positive contactor 75 is provided in positive wirings 173, 174 that connect the positive terminal 51 of the battery module 50 and the motor generator 2. In other words, the electrical circuit between the positive terminal 51 of the battery module 50 and the motor generator 2 includes the positive wiring 173 and the positive wiring 174. The positive contactor 75 is electrically connected to the ECU 150 by a signal line 181, and opens and closes the positive wirings 173, 174 based on a control signal transmitted from the ECU 150 via the signal line 181.

[0018] The positive electrode contactor 75 may be electrically connected to the BMU 85. In this case, the positive electrode contactor 75 opens and closes the positive electrode wirings 173, 174 based on a control signal transmitted from the BMU 85. In the description of this embodiment, a case where the positive electrode contactor 75 is electrically connected to the ECU 150 by a signal line 181 will be exemplified.

[0019] The negative contactor 76 is provided in an electrical circuit between the negative terminal 52 of the battery module 50 and the motor generator 2. Specifically, as shown in FIG. 1 , the negative contactor 76 is provided in a negative wiring 175 that connects the negative terminal 52 of the battery module 50 and the motor generator 2. In other words, the electrical circuit between the negative terminal 52 of the battery module 50 and the motor generator 2 includes the negative wiring 175. The negative contactor 76 is electrically connected to the BMU 85 by a signal line 182, and opens and closes the negative wiring 175 based on a control signal transmitted from the BMU 85 through the signal line 182.

[0020] The negative contactor 76 may be electrically connected to the ECU 150. In this case, the negative contactor 76 opens and closes the negative wiring 175 based on a control signal transmitted from the ECU 150. In the description of this embodiment, a case where the negative contactor 76 is electrically connected to the BMU 85 by a signal line 182 will be exemplified.

[0021] The BMU 85 is an example of a "control circuit" in the present invention. The BMU 85 controls the overall voltage of the battery module 50. That is, the BMU 85 is electrically connected to the ECU 150 by a signal line 193, and controls the negative contactor 76 based on a control signal transmitted from the ECU 150 through the signal line 193. The ECU 150 and the BMU 85 communicate with each other, for example, via a CAN, and monitor each other's status.

[0022] The BMU 85 also monitors the state of the battery module 50 and can detect abnormalities in the battery module 50. For example, the BMU 85 detects an overcharge (minor fault) abnormality or an overcharge (major fault) abnormality based on the voltage of the battery cell 510 acquired from the CMU 87. Alternatively, the BMU 85 detects an overdischarge (minor fault) abnormality or an overdischarge (major fault) abnormality based on the voltage of the battery cell 510 acquired from the CMU 87. Alternatively, the BMU 85 detects an overtemperature (minor fault) abnormality based on the temperature of the battery cell 510 acquired from the CMU 87. Alternatively, the BMU 85 detects an overcurrent abnormality based on a current value acquired from a current value detection unit 65 provided in the positive electrode wiring 174.

[0023] The CMU 87 is an example of a "control circuit" of the present invention. The CMU 87 monitors the states of the battery cells 510 included in the battery module 50 and sends the information to the BMU 85. If the battery module 50 includes multiple battery cells 510, the CMU 87 monitors the voltage of each battery cell 510 and sends information about the voltage of each battery cell 510 to the BMU 85 via a signal line 191. The CMU 87 also obtains information about the temperature of the battery cell 510 detected by the temperature detection unit 67 via a signal line 183 and sends the information about the temperature of the battery cell 510 to the BMU 85 via the signal line 191. The CMU 87 may be provided separately from the BMU 85 or may be provided integrally with the BMU 85.

[0024] As described above, the negative electrode wiring 175 electrically connects the negative electrode terminal 52 of the battery module 50 to the motor generator 2 and serves as the ground 100B. For example, the negative electrode wiring 175 is connected to the body of a vehicle or the like in which the hybrid system 10 is mounted and is grounded. The positive electrode wiring 173 electrically connects the positive electrode terminal 51 of the battery module 50 to the motor generator 2 and also electrically connects the motor generator 2 to the DC / DC converter 70. In the hybrid system 10 shown in FIG. 1 , when the battery module 50 is a 48V lithium-ion battery, the potential of the positive electrode wirings 173, 174 relative to the negative electrode wiring 175 is 48V.

[0025] The DC / DC converter 70 is electrically connected to the battery 80 via a positive wiring 171 and a negative wiring 172. An example of the battery 80 is a 12V lead-acid battery. The negative wiring 172 electrically connects the negative terminal 82 of the battery 80 to the DC / DC converter 70 and serves as ground 100B. For example, the negative wiring 172 is connected to the body of a vehicle or the like in which the hybrid system 10 is mounted and is grounded. The positive wiring 171 electrically connects the positive terminal 81 of the battery 80 to the DC / DC converter 70. If the battery 80 is a 12V lead-acid battery as in the hybrid system 10 shown in FIG. 1 , the potential of the positive wiring 171 relative to the negative wiring 172 is 12V.

[0026] As described above, the motor generator 2 generates electricity by converting kinetic energy of a vehicle or the like equipped with the hybrid system 10 into electrical energy using regenerative braking or the like. The motor generator 2 supplies voltage to the battery module 50 to charge the battery module 50, and also supplies voltage to the battery 80 to charge the battery 80. Taking the hybrid system 10 shown in FIG. 1 as an example, the potential of the positive wiring 173 relative to the negative wiring 175 is 48 V. That is, the voltage generated by the motor generator 2 is 48 V. Meanwhile, the potential of the positive wiring 171 relative to the negative wiring 172 is 12 V. Therefore, the DC / DC converter 70 converts the 48 V voltage generated by the motor generator 2 to a 12 V voltage. As a result, the motor generator 2 can supply a 12 V voltage to the battery 80 via the DC / DC converter 70, thereby charging the battery 80.

[0027] Furthermore, DC / DC converter 70 is electrically connected to battery module 50 and battery 80, and can charge and discharge between battery module 50 and battery 80 based on control signals transmitted from ECU 150. For example, DC / DC converter 70 can discharge battery module 50 and charge battery 80 by converting voltage and causing a constant current (e.g., 10 A) to flow from battery module 50 to battery 80. Alternatively, for example, DC / DC converter 70 can discharge battery 80 and charge battery module 50 by converting voltage and causing a constant current (e.g., 10 A) to flow from battery 80 to battery module 50.

[0028] The hybrid system 10 according to this embodiment has the function of safely shutting off the electrical circuit that supplies power from the battery module 50 to the motor generator 2 when an abnormality occurs in the battery module 50 or when the entire hybrid system 10 is shut down.

[0029] For example, when the ignition switch is turned on, the ECU 150 transmits a control signal to the positive contactor 75 through a signal line 181 and executes control to close the positive contactor 75, thereby electrically connecting the positive wiring 174. Furthermore, the BMU 85 executes control to close the negative contactor 76 based on a control signal transmitted from the ECU 150 through a signal line 193, thereby electrically connecting the negative wiring 175. This enables the battery module 50 to supply power to the motor generator 2.

[0030] On the other hand, for example, when the ignition switch is turned off, the ECU 150 transmits a control signal to the positive contactor 75 through a signal line 181 and executes control to open the positive contactor 75, thereby electrically disconnecting the positive wiring 174. Furthermore, the BMU 85 executes control to open the negative contactor 76 based on a control signal transmitted from the ECU 150 through a signal line 193, thereby electrically disconnecting the negative wiring 175. This stops the supply of power from the battery module 50 to the motor generator 2.

[0031] Furthermore, when the BMU 85 detects an abnormality in the battery module 50, for example, the ECU 150 transmits a first disconnection signal R1 to the positive contactor 75 via a signal line 181 and executes control to open the positive contactor 75, thereby electrically disconnecting the positive wiring 174. Furthermore, the BMU 85 independently transmits a second disconnection signal R2 to the negative contactor 76 via a signal line 182, without relying on a control signal transmitted from the ECU 150, and executes control to open the negative contactor 76, thereby electrically disconnecting the negative wiring 175.

[0032] Alternatively, as described above, the ECU 150 and the BMU 85 communicate with each other and monitor each other's states. When the ECU 150 detects an abnormality in the BMU 85, the ECU 150 transmits a first shutoff signal R1 to the positive contactor 75 via a signal line 181 and executes control to open the positive contactor 75, thereby electrically shutting off the positive wiring 174. When the BMU 85 detects an abnormality in the ECU 150, the BMU 85 independently transmits a second shutoff signal R2 to the negative contactor 76 via a signal line 182, without relying on a control signal transmitted from the ECU 150, thereby executing control to open the negative contactor 76, thereby electrically shutting off the negative wiring 175.

[0033] According to the hybrid system 10 described above, two contactors (in the present embodiment, the positive electrode contactor 75 and the negative electrode contactor 76) are provided in the electric circuit (in the present embodiment, the positive electrode wirings 173, 174 and the negative electrode wiring 175) that supplies electric power from the battery module 50 to the motor generator 2, and the ECU 150 controls the positive electrode contactor 75, and the BMU 85 controls the negative electrode contactor 76. Therefore, even if an abnormality occurs in the battery module 50 or in either the ECU 150 or the BMU 85, the hybrid system 10 according to the present embodiment can shut off the electric circuit that supplies electric power from the battery module 50 to the motor generator 2. This allows the hybrid system 10 to improve the safety of the battery module 50 that supplies electric power to the motor generator 2.

[0034] (Battery Pack) FIG. 2 is an external perspective view illustrating a battery pack according to this embodiment. FIG. 3 is a partially exploded perspective view illustrating a battery pack according to this embodiment. FIG. 3 shows a state in which the housing cover 420 of the housing 400 of the battery pack 40 is open. The battery pack 40 includes a battery module 50, a control circuit including a BMU 85 and a CMU 87, and the housing 400 that houses the battery module 50 and the control circuit. The housing main body 410 and the housing cover 420 are formed by casting using a metal material including, for example, aluminum. A seal (not shown) is provided at the joint between the housing main body 410 and the housing cover 420. By placing the housing cover 420 on the housing main body 410 and fastening it in place with screws, for example, the inside of the housing 400 becomes watertight.

[0035] The battery module 50 housed in the housing 400 has a plurality of battery cells 510. The plurality of battery cells 510 are housed in a cell case 500. The cell case 500 has a fixing portion 500a for fixing the plurality of battery cells 510 housed in the cell case 500 to the housing 400. One battery module 50 may be housed in one housing 400, or a plurality of battery modules 50 may be housed in one housing 400.

[0036] 2 and 3, two battery modules 50 are housed in one housing 400. For example, when configuring a 48V battery pack 40, in this embodiment, two 24V battery modules 50 are housed in the housing 400 and connected in series. Nine battery cells 510 are housed in the cell case 500 of one battery module 50.

[0037] In this embodiment, the CMU 87 is attached to the cell case 500 in one battery module 50. That is, the CMU 87, which monitors the state of each of the multiple battery cells 510 housed in the cell case 500, is attached to the cell case 500 that houses the battery cell 510.

[0038] 3 , when two battery modules 50 are housed in the housing 400 of one battery pack 40, a configuration is adopted in which one BMU 85 is shared. That is, one BMU 85 is provided in the housing 400, and this BMU 85 performs control to monitor the entirety of multiple (e.g., two) battery modules 50. Since each battery module 50 has a CMU 87 in the cell case 500 that monitors the multiple battery cells 510 in that battery module 50, even when the number of battery modules 50 housed in the battery pack 40 is changed, it is only necessary to change the arrangement of the battery modules 50 without changing the BMU 85.

[0039] For example, in the case of the battery pack 40 according to this embodiment, two battery modules 50 are housed in the housing 400 and are configured for 48V specifications, but if these are combined into one to change to a 24V specification, this can be achieved by removing one of the two battery modules 50 from the housing 400. Also, if three battery modules 50 are housed in one housing 400 to achieve a 72V specification, this can be achieved without requiring a major design change to the BMU 85 by changing the size of the housing 400 so that it can house three battery modules 50.

[0040] (Battery Module) FIG. 4 is a partially exploded perspective view illustrating an example of a battery module. FIG. 4 shows a state in which one battery cell is removed from the cell case. The cell case 500 is formed of, for example, resin. The cell case 500 has an accommodation portion 501 that accommodates the battery cells 510 and a mounting portion 502 on which the CMU 87 is placed. The accommodation portion 501 is box-shaped so that it can accommodate multiple battery cells 510, and the mounting portion 502 is flat so that the substrate of the CMU 87 can be easily placed thereon. In this embodiment, the multiple battery cells 510 are arranged side by side and stacked in the accommodation portion 501.

[0041] The battery cell 510 is provided in a generally rectangular parallelepiped shape having a flat surface 510a and a bottom surface 510b facing each other, and four side surfaces 510c each having a smaller area than the flat surface 510a and the bottom surface 510b. The battery cells 510 are arranged side by side along the bottom surface 400a (see FIG. 3 ) of the housing 400 so that the bottom surface 510b faces the bottom surface 400a. Specifically, the battery cells 510 are arranged so that the bottom surface 510b faces a mounting surface 501a, which is the inner bottom of the accommodation portion 501 of the cell case 500. When the cell case 500 is accommodated in the housing 400, the mounting surface 501a of the accommodation portion 501 is generally parallel to the bottom surface 400a of the housing 400. Therefore, the bottom surface 510b of the battery cell 510 faces the bottom surface 400a of the housing 400. By placing each of the plurality of battery cells 510 with the bottom surface 510b facing the placement surface 501a, the battery module 50 can be made thinner.

[0042] 4, the battery cells 510 are housed in a two-tiered stack in the housing portion 501 of the cell case 500. Five battery cells 510 are arranged side by side in the first tier, and four battery cells 510 are arranged side by side in the second tier. The very end has only one tier of battery cells 510, and a mounting portion 502 for mounting the CMU 87 is provided in the space above that, which will be the second tier.

[0043] Fig. 5 is a perspective view illustrating the connection of multiple battery cells. Fig. 5 shows a perspective view of multiple battery cells 510 in Fig. 4 as seen from the opposite side to that in Fig. 4. For convenience of explanation, the cell case 500 and the CMU 87 are omitted in Fig. 5. For the cell case 500 and the CMU 87, refer to Fig. 4. When one cell case 500 accommodates an odd number (n) of battery cells 510, it is preferable that one cell case 500 accommodates a first-stage cell group CG1 in which {(n+1) / 2} battery cells 510 are juxtaposed in a direction along the bottom surface 400a of the housing 400 (see Figure 3) (hereinafter simply referred to as the "first direction D1"), and a second-stage cell group CG2 in which {(n-1) / 2} battery cells 510 are juxtaposed in the first direction D1 and stacked with the first-stage cell group CG1 in a normal direction of the bottom surface 400a of the housing 400 (hereinafter simply referred to as the "normal direction D3").

[0044] 5 , when nine battery cells 510 are housed in one cell case 500, the battery cells are stacked in two tiers, with the first tier being a first-tier cell group CG1 and the second tier being a second-tier cell group CG2. In the first-tier cell group CG1, five battery cells 510 are arranged side by side in the first direction D1, and in the second-tier cell group CG2, four battery cells 510 are arranged side by side in the first direction D1. The nine battery cells 510 arranged in this manner are housed in the housing portion 501 of the cell case 500.

[0045] The CMU 87 is disposed on the second-stage cell group CG2 side of the first-stage cell group CG1, aligned with the second-stage cell group CG2 in the first direction D1. For example, in the case of nine battery cells 510, five battery cells 510 are arranged side by side as the first-stage cell group CG1, and four battery cells 510 are arranged side by side as the second-stage cell group CG2, and these are stacked in the normal direction D3. As a result, a vacant space equivalent to one cell is formed in the second-stage cell group CG2. This vacant space is used as the mounting portion 502 shown in FIG. 4, and the CMU 87 is disposed therein. This allows for efficient use of the space in the battery module 50. Note that, although the present embodiment illustrates an example in which an odd number of battery cells 510 are provided in one battery module 50, an even number of battery cells 510 may also be provided.

[0046] As shown in FIG. 5 , one of the side surfaces 510c of the rectangular parallelepiped battery cell 510 is provided with a positive electrode (+), a negative electrode (-), and a gas release valve V (cell valve). When multiple battery cells 510 are placed and stacked, the side surfaces 510c with the positive electrode (+) and negative electrode (-) are oriented to face the same side. In this case, the arrangement of the positive electrodes (+) and negative electrodes (-) of the battery cells 510 is reversed between the first-stage cell group CG1 and the second-stage cell group CG2. That is, in the first-stage cell group CG1, the battery cells 510 are arranged such that the electrodes of the multiple battery cells 510 are arranged in the order of positive electrode (+), negative electrode (-), positive electrode (+), negative electrode (-), ... from one end to the other end in the first direction, while in the second-stage cell group CG2, the battery cells 510 are arranged in the opposite order of negative electrode (-), positive electrode (+), negative electrode (-), positive electrode (+), ...

[0047] The plurality of battery cells 510 constituting the first-stage cell group CG1 are conductively connected by a first connecting bus bar B1 in the order of arrangement from one end to the other end in the first direction D1. The plurality of battery cells 510 constituting the second-stage cell group CG2 are conductively connected by a second connecting bus bar B2 in the order of arrangement from one end to the other end in the first direction D1. The battery cell 510 arranged at the other end of the first-stage cell group CG1 and the battery cell 510 arranged at the other end of the second-stage cell group CG2 are conductively connected by a third connecting bus bar B3. Here, the bus bar is a metal (e.g., copper) plate formed into a predetermined shape. In this embodiment, a bus bar is used as a member for conductively connecting adjacent battery cells 510, but a conductor other than a bus bar may also be used. In the battery cells 510 arranged at the other end of each of the first-stage cell group CG1 and the second-stage cell group CG2 (two battery cells 510 stacked at the other end), the electrode polarities are aligned in the stacking direction with positive pole + and negative pole -, so simply by attaching the third connecting bus bar B3 straight in the stacking direction, the multiple battery cells 510 of the first-stage cell group CG1 and the second-stage cell group CG2 are connected in series.

[0048] FIG. 6 is a perspective view illustrating an arrangement of multiple battery modules. FIG. 7 is a plan view illustrating an arrangement of multiple battery modules. Here, FIGS. 6 and 7 illustrate an example in which two battery modules 50 shown in FIG. 5 are arranged. For ease of explanation, the cell case 500 and CMU 87 are omitted from FIG. 6. For the cell case 500 and CMU 87, refer to FIG. 4. When arranging multiple battery modules 50, the multiple battery modules 50 may be arranged side by side in a second direction (hereinafter simply referred to as the "second direction D2") that intersects with the first direction D1 along the bottom surface 400a (see FIG. 2) of the housing 400 (see FIG. 2). In this arrangement of the multiple battery modules 50, the battery cells 510 are arranged so that the positive poles (+), negative poles (-), and valves (V) of adjacent battery modules 50 face each other.

[0049] As a result, the first connecting bus bar B1, the second connecting bus bar B2, and the third connecting bus bar B3 in each battery module 50 are arranged to face each other between adjacent battery modules 50. By having the first connecting bus bar B1, the second connecting bus bar B2, and the third connecting bus bar B3 in each battery module 50 facing each other, it becomes easier to unify the conduction paths in the multiple battery modules 50, and space savings in the battery pack 40 can be achieved.

[0050] Furthermore, the battery modules 50 adjacent to each other in the second direction D2 are electrically connected to each other at one end in the first direction D1 by a fourth connecting bus bar B4. In this case, it is preferable that the two battery cells 510 connected by the fourth connecting bus bar B4 are arranged in the same row. This allows the fourth connecting bus bar B4 to be attached in the same row.

[0051] When adjacent battery modules 50 are connected in series, to arrange two battery cells 510 connected by the fourth connecting bus bar B4 in the same row, the arrangement of the positive electrodes + and negative electrodes − of two battery cells 510 facing each other (two battery cells 510 facing each other in the second direction D2 between adjacent battery modules 50) can be reversed among the multiple battery cells 510 of adjacent battery modules 50. This causes the positive electrodes + and negative electrodes − of the two battery cells 510 connected by the fourth connecting bus bar B4 to face each other, and enables the connection of the positive electrodes + and negative electrodes − at the fourth connecting bus bar B4 to be performed over the shortest distance.

[0052] For example, the battery module 50 on one side of two adjacent battery modules 50 is connected by a first connecting bus bar B1 in order from the battery cell 510 at one end in the first direction D1 of the first stage cell group CG1 to the battery cell 510 at the other end, the battery cell 510 of the first stage cell group CG1 located at the other end and the battery cell 510 of the second stage cell group CG2 are connected by a third connecting bus bar B3, and the battery cell 510 at the other end in the first direction of the second stage cell group CG2 is connected by a second connecting bus bar B2 in order from the battery cell 510 at the other end in the first direction to the battery cell 510 at one end.

[0053] On the other hand, the battery module 50 on the other side of two adjacent battery modules 50 is connected in the opposite direction to the battery module 50 on one side by a second connecting bus bar B2 from the battery cell 510 at one end of the second-stage cell group CG2 in the first direction D1 to the battery cell 510 at the other end, the battery cells 510 of the second-stage cell group CG2 located at the other end and the battery cells 510 of the first-stage cell group CG1 are connected by a third connecting bus bar B3, and the battery cells 510 at the other end of the first-stage cell group CG1 in the first direction are connected by a first connecting bus bar B1 from the battery cell 510 at the other end of the first-stage cell group CG1 in the first direction to the battery cell 510 at one end.

[0054] In two adjacent battery modules 50, the battery cells 510 at one end in the first direction D1 of the respective second-stage cell groups CG2 are connected to each other by the fourth connecting bus bar B4.

[0055] In other words, the connection configuration using the first connecting bus bar B1 to the fourth connecting bus bar B4 connects from one end to the other end of the first-stage cell group CG1 on one side of two adjacent battery modules 50, connects at the other end to the second-stage cell group CG2 and returns to one end, connects at the other end of the second-stage cell group CG2 to the battery module 50 on the other side, connects from one end to the other end of the second-stage cell group CG2, and connects at the other end to the first-stage cell group CG1 and returns to one side. This connection configuration enables connections to be made via the shortest route.

[0056] Furthermore, the battery module 50 is provided with wiring (not shown) that sends information indicating the state (voltage and temperature) of the battery cells 510 to the CMU 87. When multiple battery modules 50 are arranged, this wiring is arranged so that it sends information to the CMU 87 between adjacent battery modules 50. This makes it possible to effectively use the space between adjacent battery modules 50 and send the wiring together to the CMU 87.

[0057] In addition, by arranging the valves V of each battery cell 510 in each battery module 50 so that they face each other between adjacent battery modules 50, the space between adjacent battery modules 50 can be used as a flow path for gas released from the valves.

[0058] 3, when the housing cover 420 is provided with a vent valve 425 that opens when the internal pressure of the housing 400 reaches a predetermined pressure, it is preferable to position the vent valve 425 so that it overlaps the space between adjacent battery modules 50 when viewed in the normal direction (see the figure). This allows gas released from the valve to be efficiently discharged from the vent valve 425 using the space between adjacent battery modules 50 as a flow path.

[0059] Although the above example shows five battery cells 510 arranged side by side in the first-stage cell group CG1 and four battery cells 510 arranged side by side in the second-stage cell group CG2, which is one less than the number of battery cells 510 in the first-stage cell group CG1, the present invention is not limited to this. The number of battery cells 510 in the second-stage cell group CG2 may be two or more less than the number of battery cells 510 in the first-stage cell group CG1, the juxtaposition of the multiple battery cells 510 in the second-stage cell group CG1 may be discontinuous, and the position of the mounting portion 502 (see FIG. 4 ) may not be at the end of the second-stage cell group CG2.

[0060] (Individual Cell Case) FIG. 8 is a plan view illustrating an example of an individual cell case. The individual cell case 550 is a case that houses one battery cell 510. The individual cell case 550 includes an individual cell case main body 551 that houses one battery cell 510, and a connecting portion 552 provided on the periphery of the individual cell case main body 551. The individual cell case main body 551 is box-shaped and houses one battery cell 510 therein. The individual cell case main body 551 has a substantially rectangular (e.g., square) outer shape in a plan view. The connecting portion 552 is provided at each corner of the individual cell case main body 551. The connecting portion 552 may be provided at the center of each side of the individual cell case main body 551. The connecting portion 552 may be provided with a hole for bolt fastening, or may be provided with an engagement portion that is fitted by recesses and projections or the like.

[0061] FIG. 9 is a plan view showing an arrangement example (part 1) of individual cell cases. In the example shown in FIG. 9, a configuration is shown in which a plurality of individual cell cases 550 are connected vertically and horizontally along a plane. A single cell case 500 is formed by connecting a plurality of individual cell cases 550. Adjacent individual cell cases 550 in both the vertical and horizontal directions are connected using their connecting portions 552. A plurality of individual cell cases 550 may be connected vertically and horizontally along the same plane, or a plurality of individual cell cases 550 may be connected in one direction, vertically or horizontally, on the same plane. Furthermore, a multi-tier configuration may be formed by stacking a plurality of individual cell cases 550 connected on the same plane.

[0062] Fig. 10 is a perspective view showing an arrangement example (part 2) of individual cell cases. In the example shown in Fig. 10, a configuration is shown in which a plurality of individual cell cases 550 are stacked and connected. A single cell case 500 is formed by connecting a plurality of individual cell cases 550. Adjacent individual cell cases 550 in the stacking direction are connected to each other using their connecting portions 552. Bolts may be fastened so as to penetrate the connecting portions 552 of all of the stacked individual cell cases 550.

[0063] When connecting multiple individual cell cases 550 as shown in Figures 9 and 10, the positive electrode + or negative electrode - of the battery cell 510 may be electrically connected to the connecting portion 552, and adjacent (or overlapping) individual cell cases 550 may be connected to each other by the connecting portion 552, thereby making it possible to electrically connect the battery cells 510 of the multiple individual cell cases 550 in series or in parallel.

[0064] According to this embodiment, it is possible to provide a battery pack 40 that can flexibly respond to changes in specifications.

[0065] (Another Battery Pack) Next, another battery pack will be described. Note that, where components of the other battery pack 40 are similar to those of the battery pack 40 described above with reference to FIGS. 2 to 10 , redundant description will be omitted as appropriate, and the following description will focus on the differences. FIG. 11 is a partially exploded perspective view illustrating another battery pack according to this embodiment. FIG. 11 shows the housing 400 of the battery pack 40 with the housing cover 420 and the thermal conduction member 600 open. FIG. 12 is a schematic cross-sectional view illustrating the battery pack according to this embodiment. Note that the external perspective view of the other battery pack viewed obliquely is similar to the external perspective view shown in FIG. 2. The battery pack 40 includes a battery module 50, a control circuit including a BMU 85 and a CMU 87, and a housing 400 that accommodates the battery module 50 and the control circuit. The housing main body 410 and the housing cover 420 are formed by casting using a metal material, such as aluminum. A seal (not shown) is provided at the joint between the housing body 410 and the housing cover 420, and by placing the housing cover 420 over the housing body 410 and fastening it in place with screws, for example, the inside of the housing 400 becomes watertight.

[0066] The battery module 50 housed in the housing 400 includes, for example, a plurality of battery cells 510. One battery module 50 may be housed in one housing 400, or a plurality of battery modules 50 may be housed in one housing 400.

[0067] The battery cells 510 are provided in a generally rectangular parallelepiped shape having flat surfaces (top surface 510a and bottom surface 510b) facing each other and four side surfaces 510c each having a smaller area than the top surface 510a and bottom surface 510b. The battery cells 510 are arranged side by side along the bottom surface 400a of the housing 400 so that the bottom surface 510b faces the bottom surface 400a.

[0068] The battery module 50 may have a plurality of battery cells 510. In this case, the plurality of battery cells 510 are preferably arranged side by side along the bottom surface 400a of the housing 400. The battery cells 510 may be arranged in a single row or in a plurality of rows in the housing 400. In the case of a plurality of rows, the battery cells 510 are preferably arranged such that the top surface portions 510a and bottom surface portions 510b of two battery cells 510 in the stacking direction face each other.

[0069] An insulating heat-conducting member 600 is provided between the battery module 50 accommodated in the housing 400 and the housing 400. The heat-conducting member 600 is made of, for example, a silicone sheet having insulating and thermally conductive properties. The heat-conducting member 600 is disposed between the upper surface 510a of the battery cell 510 and the ceiling surface 420a of the housing cover 420 (housing 400) that faces the bottom surface 400a of the housing 400. The heat-conducting member 600 is preferably in contact with both the upper surface 510a of the battery cell 510 and the ceiling surface 420a of the housing cover 420. Note that some other member may be interposed between the heat-conducting member 600 and the upper surface 510a and between the heat-conducting member 600 and the ceiling surface 420a.

[0070] The battery cell 510 is arranged so that the bottom surface portion 510b faces the bottom surface 400a of the housing 400, and thus the top surface portion 510a of the battery cell 510 faces the ceiling surface 420a of the housing cover 420. In the battery cell 510, the area of ​​the top surface portion 510a is larger than the area of ​​the side surface portion 510c. Therefore, when the top surface portion 510a and the heat conduction member 600 come into contact (including when the contact is via a member), heat generated in the battery cell 510 can be effectively conducted to the heat conduction member 600. Furthermore, when the heat conduction member 600 comes into contact (including when the contact is via a member) with the ceiling surface 420a of the housing cover 420, heat conducted from the battery cell 510 to the heat conduction member 600 can be effectively conducted to the housing cover 420, and can be easily dissipated from the housing 400 to the outside.

[0071] The battery pack 40 may include a plurality of battery modules 50. In this case, the plurality of battery modules 50 are preferably arranged side by side along the bottom surface 400a of the housing 400. This prevents the upper surface portions 510a of the battery cells 510 in the plurality of battery modules 50 from overlapping, which is advantageous in terms of heat dissipation.

[0072] In a configuration in which a plurality of battery modules 50 are arranged side by side, the heat conduction member 600 may have a portion that is disposed between adjacent battery modules 50 among the plurality of battery modules 50. By disposing a portion of the heat conduction member 600 between adjacent battery modules 50, heat can be more easily conducted to the heat conduction member 600 not only from the upper surface portion 510 a of the battery cell 510 but also from a portion of the side surface portion 510 c.

[0073] FIG. 13 is a perspective view illustrating the ceiling surface of the housing cover. The housing cover 420 is formed, for example, by casting using aluminum. The ceiling surface 420a of the housing cover 420 has a first region A1 facing the battery module 50 (see FIG. 11) and a second region A2 outside the first region A1. In the housing cover 420, the surface roughness of the first region A1 is preferably lower than that of the second region A2. For example, when the housing cover 420 is formed by casting, the surface of the casting mold is transferred to both the first region A1 and the second region A2, resulting in a relatively rough surface roughness. Therefore, the first region A1 is subjected to a cutting process or the like to reduce the surface roughness of the first region A1 compared to the second region A2. This improves the adhesion between the first region A1 and the thermal conduction member 600 on the ceiling surface 420a of the housing cover 420, allowing for more effective heat transfer from the thermal conduction member 600 to the housing cover 420.

[0074] According to this embodiment, it is possible to provide a battery pack 40 that can efficiently release heat from the battery cells 510 to the outside.

[0075] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. For example, the configurations of the above embodiments can be partially omitted or arbitrarily combined in a different manner from the above.

[0076] 1...engine, 2...motor generator, 10...hybrid system, 40...battery pack, 50...battery module, 51...positive terminal, 52...negative terminal, 65...current value detection unit, 67...temperature detection unit, 70...DC / DC converter, 75...positive contactor, 76...negative contactor, 80...battery, 81...positive terminal, 82...negative terminal, 85...BMU, 87...CMU, 100B...ground, 150...ECU, 171...positive wiring, 172...negative wiring, 173...positive wiring, 174...positive wiring, 175...negative wiring, 181...signal line, 182...signal line, 183...signal line, 191...signal line, 193...signal line, 400...housing, 400a...bottom, 410...housing body , 420...housing cover, 420a...ceiling surface, 425...vent valve, 500...cell casing, 500a...fixing portion, 501...accommodating portion, 501a...mounting surface, 502...mounting portion, 510...battery cell, 510a...upper surface (flat portion), 510b...bottom surface (flat portion), 510c...side portion, 550...individual cell casing, 551...individual cell casing body, 552...connecting portion, 600...heat conducting member, A1...first region, B1...first connecting bus bar, B2...second connecting bus bar, B3...third connecting bus bar, B4...fourth connecting bus bar, CG1...first stage cell group, CG2...second stage cell group, D1...first direction, D2...second direction, D3...normal direction, R1...first shut-off signal, R2...second shut-off signal, V...valve

Claims

1. A battery pack mounted on a hybrid system, comprising: a battery module that supplies power to a motor generator of the hybrid system; a control circuit that controls the battery module; and a housing that accommodates the battery module and the control circuit, wherein the battery module has a plurality of battery cells and a cell case that accommodates the plurality of battery cells, the control circuit has a BMU (Battery Management Unit) that monitors and controls the overall state of the battery pack, and a CMU (Cell Management Unit) that monitors the state of each of the plurality of battery cells and sends information to the BMU, and the CMU is attached to the cell case in the battery module.

2. The battery pack according to claim 1, wherein the cell case has a cell case body and a plurality of housing portions provided in the cell case body and housing each of the plurality of battery cells.

3. The battery pack of claim 1, wherein the cell case has a plurality of individual cases housing each of the plurality of battery cells.

4. The battery pack according to claim 1, wherein the plurality of battery cells are arranged side by side along a bottom surface of the housing and stacked in a normal direction to the bottom surface.

5. The battery pack of claim 1, wherein all of said plurality of battery cells are arranged side-by-side along a bottom surface of said housing.

6. The battery pack as described in claim 1, wherein each of the plurality of battery cells is provided in a generally rectangular parallelepiped shape having a flat surface and a bottom surface facing each other and four side surfaces narrower in area than the flat surface and the bottom surface, and the plurality of battery cells are juxtaposed along the bottom surface of the housing such that the bottom surface faces the bottom surface.

7. The battery pack of claim 1, wherein the battery module has n battery cells (n is an odd number), the cell case accommodates a first stage cell group in which {(n+1) / 2} battery cells are juxtaposed in a first direction along a bottom surface of the housing, and a second stage cell group in which {(n-1) / 2} battery cells are juxtaposed in the first direction and stacked with the first stage cell group in a direction normal to the bottom surface, and the CMU is positioned on the side of the first stage cell group that is adjacent to the second stage cell group and aligned with the second stage cell group in the first direction.

8. The battery pack according to claim 7, comprising a plurality of the battery modules, the plurality of battery modules being arranged side by side with one another along the bottom surface in a second direction intersecting the first direction.

9. The battery pack according to claim 8, wherein the battery cells have cell valves that open when pressure within the cells exceeds a predetermined value, and the cell valves of the battery cells facing each other between adjacent battery modules among the plurality of battery modules are arranged so as to face each other.

10. The battery pack as described in claim 9, further comprising a vent valve provided in the housing that opens when the internal pressure of the housing reaches a predetermined pressure, the vent valve being positioned so as to overlap with a gap between adjacent ones of the plurality of battery modules when viewed in the normal direction.

11. The battery pack according to claim 8, wherein the battery cells have positive and negative electrode terminals, and the electrode terminals of the battery cells facing each other between adjacent battery modules among the plurality of battery modules are arranged so as to face each other.

12. The battery pack according to claim 11, wherein wiring is arranged between adjacent battery modules among the plurality of battery modules for sending information indicating a state of each of the plurality of battery cells to the CMU.

13. The battery pack as described in claim 7, wherein the plurality of battery cells constituting the first stage cell group are conductively connected by a first connecting bus bar in the order of arrangement from the one end to the other end in the first direction, the plurality of battery cells constituting the second stage cell group are conductively connected by a second connecting bus bar in the order of arrangement from the one end to the other end in the first direction, and the battery cell arranged at the other end of the first stage cell group and the battery cell arranged at the other end of the second stage cell group are conductively connected by a third connecting bus bar.

14. The battery pack according to claim 13, comprising a plurality of the battery modules, the plurality of battery modules being juxtaposed to one another in a second direction intersecting the first direction along the bottom surface, and the battery modules adjacent to each other in the second direction being conductively connected at the one ends by a fourth connecting bus bar.

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