JP2020126780A - Battery pack - Google Patents

Abstract

To provide a battery pack in which uneven current amount flowing in each of a plurality of switches connected in parallel is suppressed.SOLUTION: A battery pack includes a battery pack 10, and a first opening/closing portion 60a and a second opening/closing portion 60b electrically connected in parallel between a first terminal and a second terminal, and further includes a first power supply bus bar 51 that connects the plurality of opening/closing portion and the first terminal, and a second power supply bus bar 52 that connects the plurality of opening/closing portions and the second terminal. The electrical resistance of an energizing path between the first opening/closing portion and the first terminal of the first bus bar is lower than the electrical resistance of an energizing path between the second opening/closing portion and the first terminal of the first bus bar. The electric resistance of an energizing path between the first opening/closing portion and the second terminal in the second bus bar is higher than the electric resistance of an energizing path between the second opening/closing portion and the second terminal in the second bus bar.SELECTED DRAWING: Figure 6

Description

The disclosures described herein relate to battery packs.

As shown in Patent Document 1, a battery pack having a lithium storage battery and a switch is known.

JP, 2018-143044, A

In the battery pack described in Patent Document 1, a switch is provided on a power supply line that electrically connects two external connection terminals. The switch has a plurality of opening/closing sections in which two MOSFETs are connected in series. The plurality of opening/closing sections are connected in parallel between the two external connection terminals. If the electric resistance of the energizing path between each of the plurality of opening/closing sections and the two external connection terminals is uneven, the amount of current flowing through each of the plurality of opening/closing sections will be uneven.

Therefore, an object of the disclosure disclosed in the present specification is to provide a battery pack in which unevenness in the amount of current flowing through each of a plurality of switches connected in parallel is suppressed.

One of the disclosures is a battery (10),
A plurality of switches (60a-60e) electrically connected in parallel between a first terminal (100a, 12) and a second terminal (100b) electrically connected to the battery;
A first bus bar (51, 53) connecting each of the plurality of switches and the first terminal;
A second bus bar (52) connecting each of the plurality of switches and the second terminal,
When any two of the plurality of switches are the first switch and the second switch,
The electrical resistance of the energizing path between the first switch and the first terminal in the first bus bar is lower than the electrical resistance of the energizing path between the second switch and the first terminal in the first bus bar,
The electrical resistance of the energization path between the first switch and the second terminal in the second bus bar is higher than the electrical resistance of the energization path between the second switch and the second terminal in the second bus bar.

According to this, the electric resistance of the energization path between the first terminal (100a, 12) and the second terminal (100b) via the first switch, and the first terminal (100a, 12) via the second switch. ) And the electric resistance of the energization path between the second terminal (100b) are suppressed. Therefore, it is possible to prevent the amount of current flowing through each of the plurality of switches (60a to 60e) connected in parallel between the first terminal (100a, 12) and the second terminal (100b) from being unbalanced.

It should be noted that the reference numbers in the above parentheses only show the correspondence with the configurations described in the embodiments described later, and do not limit the technical scope in any way.

It is a block diagram which shows a power supply system. It is an exploded perspective view of a battery pack. It is a perspective view of a 1st switch and a 2nd switch. It is a chart showing a power supply bus bar. It is a front view which shows the connection state of an opening/closing part and an electric power feeding bus bar. It is a schematic diagram for demonstrating the electric current which each flows into a 1st opening/closing part and a 2nd opening/closing part. It is a front view which shows the modification of the 3rd electric power feeding bus bar. It is a front view which shows the modification of the connection state of an opening/closing part and a power supply bus bar. It is a circuit diagram for explaining the electrical resistance of the energization path. It is a circuit diagram for explaining a modification of an energization path. It is a circuit diagram for explaining a modification of an energization path. It is a circuit diagram for explaining a modification of an energization path.

Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
A battery pack 100 according to the present embodiment and a power supply system 200 including the battery pack 100 will be described based on FIGS. 1 to 6.

<Summary of power supply system>
Power supply system 200 is installed in a vehicle. The power supply system 200 includes a plurality of vehicle-mounted devices mounted on the vehicle and the battery pack 100. A storage battery 110 is one of the in-vehicle devices. The battery pack 100 has an assembled battery 10. The power supply system 200 constructs a dual power supply system by the storage battery 110 and the assembled battery 10.

An engine 140 is another on-vehicle device. The vehicle equipped with the power supply system 200 has an idle stop function of stopping the engine 140 when a predetermined stop condition is satisfied and restarting the engine 140 when a predetermined start condition is satisfied.

As shown in FIG. 1, the power supply system 200 includes a starter motor 120, a rotating electric machine 130, an electric load 150, a host ECU 160, and an MGECU 170 in addition to the storage battery 110 and the engine 140 described above. The electric load 150 has a first load 151 and a second load 152. The storage battery 110, the starter motor 120, and the first load 151 are electrically connected to the battery pack 100 via the first wire harness 210. The rotary electric machine 130 is electrically connected to the battery pack 100 via the second wire harness 220. The second load 152 is electrically connected to the battery pack 100 via the third wire harness 230.

The host ECU 160 and the MGECU 170 are electrically connected to the storage battery 110 and the assembled battery 10 of the battery pack 100, respectively, via wiring (not shown). Similarly, other various ECUs mounted on the vehicle are also electrically connected to the storage battery 110 and the assembled battery 10 via wires (not shown).

As described above, the power supply system 200 constitutes a dual power supply system that uses the storage battery 110 and the assembled battery 10 as power supplies.

<Power system components>
The storage battery 110 produces an electromotive voltage by a chemical reaction. The storage battery 110 has a larger storage capacity than the assembled battery 10. The storage battery 110 is specifically a lead storage battery. As the storage battery 110, for example, a lithium ion storage battery can be adopted.

The starter motor 120 starts the engine 140. The starter motor 120 is mechanically connected to the engine 140 when the engine 140 is started. The crankshaft of the engine 140 is rotated by the rotation of the starter motor 120. When the rotation speed of the crankshaft exceeds a predetermined rotation speed, mist-like fuel is injected from the fuel injection valve into the combustion chamber. At this time, a spark is generated by the spark plug. As a result, the fuel explodes and the engine 140 starts to rotate autonomously. The driving force of the vehicle is obtained by the power of the engine 140. When the engine 140 starts to rotate autonomously, the mechanical connection between the starter motor 120 and the engine 140 is released.

The rotary electric machine 130 performs power running and power generation. A power converter (not shown) is connected to the rotating electric machine 130. This power converter is electrically connected to the second wire harness 220.

The power converter converts a DC voltage supplied from at least one of the storage battery 110 and the assembled battery 10 into an AC voltage. This AC voltage is supplied to the rotary electric machine 130. This causes the rotating electric machine 130 to perform power running.

The rotating electric machine 130 is connected to the engine 140. The rotary electric machine 130 and the engine 140 can mutually transmit rotational energy via a belt or the like. Rotational energy generated by the power running of the rotary electric machine 130 is transmitted to the engine 140. This promotes the rotation of the engine 140. As a result, vehicle traveling is assisted. As described above, the vehicle equipped with the power supply system 200 has an idle stop function. The rotary electric machine 130 not only assists the vehicle running, but also functions to rotate the crankshaft when the engine 140 is restarted.

Rotating electric machine 130 also has a function of generating power by at least one of the rotational energy of engine 140 and the rotational energy of the wheels of the vehicle. The rotating electric machine 130 generates AC voltage by power generation. This AC voltage is converted into a DC voltage by the power converter. This DC voltage is supplied to each of the battery pack 100, the storage battery 110, and the electric load 150.

The engine 140 burns and drives the fuel to generate the propulsive force of the vehicle. As described above, when the engine 140 is started, the starter motor 120 rotates the crankshaft. However, when the engine 140 is once stopped by the idle stop and then restarted, the crankshaft is rotated by the rotating electrical machine 130 when the above-described predetermined starting condition is satisfied.

As described above, the electric load 150 has the first load 151 and the second load 152. The first load 151 includes a vehicle-mounted device such as a seat heater, a blower fan, an electric compressor, a room light, and a headlight that does not have to have a constant power supply. The second load 152 includes an in-vehicle device such as an electric shift position, an electric power steering (EPS), a brake (ABS), a door lock, a navigation system, and an audio device, which is required to have a constant power supply. The second load 152 illustrated here has the property of switching from the on state to the off state when the supply voltage falls below the reset threshold. The second load 152 includes an in-vehicle device that is more relevant to vehicle traveling than the first load 151.

The configuration in which the above-described various vehicle-mounted devices are included in the first load 151 and the second load 152 is merely an example. Various in-vehicle devices can be appropriately distributed to the first load 151 and the second load 152 according to changes in the in-vehicle system. For example, a configuration in which the first load 151 includes EPS or ABS can be adopted.

The host ECU 160 and the MGECU 170 are one of various ECUs mounted on the vehicle. These various ECUs are electrically connected to each other via a bus wiring 161 to form an in-vehicle network. The various ECUs cooperatively control the combustion of the engine 140 and the power running and power generation of the rotary electric machine 130. The host ECU 160 controls the battery pack 100. MGECU 170 controls rotating electric machine 130.

Although not shown, the power supply system 200 includes, in addition to the above-described in-vehicle devices, sensors for measuring physical quantities such as various voltages and currents, and vehicle information such as accelerator pedal depression amount and throttle valve opening. Have Detection signals detected by these various sensors are input to various ECUs. ECU is an abbreviation for electronic control unit.

<Outline of battery pack>
As shown in FIG. 1, the battery pack 100 includes an assembled battery 10, a circuit board 20, a switch 30, a sensor unit 40, and a power supply bus bar 50. As shown in FIG. 2, the battery pack 100 has a pack case 90 and a suppression plate 97. Further, the battery pack 100 has a bus bar case (not shown). The bus bar case is made of an insulating resin material and has a function of housing the power feeding bus bar 50. The power supply bus bar 50 and the bus bar case form a bus bar module.

The pack case 90 has a housing 91 shown in FIG. The housing 91 is manufactured by aluminum die casting. The housing 91 can also be manufactured by pressing iron or stainless steel. The housing 91 has higher heat transfer performance than the wiring board 21. Therefore, the housing 91 has higher heat dissipation than the wiring board 21.

The housing 91 has a bottom wall 93 and a side wall 94 standing upright from the bottom wall 93. The side wall 94 constitutes an opening. A cover (not shown) is attached to the housing 91. As a result, the opening formed by the side wall 94 is covered by the cover. The housing 91 and the cover form a storage space. The assembled battery 10, the circuit board 20, the switch 30, the sensor unit 40, the suppression plate 97, and the bus bar module are stored in this storage space. The cover is made of resin or metal.

The assembled battery 10 is smaller in size and lighter in weight than the storage battery 110. The assembled battery 10 has the property of having a higher energy density than the storage battery 110.

The circuit board 20 has a wiring board 21 and a BMU 22. A part of the switch 30 and the BMU 22 are mounted on the wiring board 21. Then, the rest of the switch 30 and the assembled battery 10 are electrically connected to the wiring board 21 via the power supply bus bar 50. This constitutes the electric circuit of the battery pack 100. The sensor unit 40 is electrically connected to this electric circuit via an insulated wire or a metal terminal.

The electric circuit of the battery pack 100 is electrically connected to the external connection terminals indicated by double circles in FIG. The external connection terminals include a first external connection terminal 100a, a second external connection terminal 100b, a third external connection terminal 100c, and a fourth external connection terminal 100d.

The first external connection terminal 100 a is electrically connected to the storage battery 110, the starter motor 120, and the first load 151 via the first wire harness 210. The second external connection terminal 100b is electrically connected to the rotary electric machine 130 via the second wire harness 220. The third external connection terminal 100c is mechanically and electrically connected to the vehicle body via a bolt described later. The fourth external connection terminal 100d is electrically connected to the second load 152 via the third wire harness 230.

Each of the first wire harness 210 to the third wire harness 230 has a metal terminal with a hole formed therein. These first wire harness 210 to third wire harness 230 are crawling around in the vehicle.

Each of the first external connection terminal 100a, the second external connection terminal 100b, and the fourth external connection terminal 100d shares a part of the bus bar case. Although not shown, the connection bolt is embedded in the terminal block of the bus bar case made of resin. A nut is fastened to the shaft portion of the connection bolt. Each of the first external connection terminal 100a, the second external connection terminal 100b, and the fourth external connection terminal 100d shares the portion of the terminal block in which the connection bolt is embedded, the connection bolt, and the nut with the bus bar case.

The head side of the connection bolt is buried in the terminal block. The shaft portion of the connecting bolt projects from the terminal block. The through hole of the power supply bus bar 50 is passed through the shaft portion of the connection bolt. Then, the nut is fastened to the shaft portion of the connection bolt. As a result, the power supply bus bar 50 is fixed to the terminal block. A bus bar module is constructed. The bus bar module is fixed to the housing 91 by bolts (not shown).

Then, the hole of the metal terminal of the wire harness is passed through the shaft portion of the connection bolt. Then, a nut (not shown) is fastened to the tip side of the shaft portion of the connection bolt. This mechanically connects the metal terminal of the wire harness to the shaft portion of the connection bolt. At the same time, the metal terminal is electrically connected to the power supply bus bar 50.

The third external connection terminal 100c is a bolt hole formed in the housing 91. The third external connection terminal 100c is connected to the vehicle body via a bolt or a wire harness. As a result, the housing 91 is at the ground potential. The battery pack 100 is body-grounded.

<Battery pack components>
Next, the components of the battery pack 100 will be individually described. In doing so, hereinafter, the three directions which are orthogonal to each other will be referred to as the x direction, the y direction, and the z direction. The x direction is along the left-right direction of the vehicle. The y direction is along the front-rear direction of the vehicle. The z direction is along the vertical direction of the vehicle.

The assembled battery 10 has a plurality of battery cells connected in series and a battery case 11 that houses the plurality of battery cells. The battery cell is specifically a lithium ion storage battery. A lithium ion storage battery produces an electromotive voltage by a chemical reaction. A current flows through the battery cell due to the generation of the electromotive voltage. As a result, the battery cells generate heat and generate gas. Therefore, the battery cell expands. The battery cell is not limited to the above example. For example, as a battery cell, a secondary battery such as a nickel hydrogen secondary battery or an organic radical battery can be adopted.

The battery cell has a rectangular parallelepiped shape. The battery cell has two main surfaces facing in the z direction. The area of these two main surfaces is larger than that of the other four surfaces. The length (thickness) between the two main surfaces is thin. Thus, the battery cell has a flat shape with a small thickness in the z direction.

The assembled battery 10 of this embodiment has five battery cells. Three of these five battery cells are stacked in the z direction to form a first battery stack. The remaining two battery cells are stacked in the z direction to form a second battery stack. These two battery stacks are arranged in the x direction. The arrangement of the five battery cells shown above is held by the battery case 11.

The battery case 11 has a box made of resin and a connection terminal connected to the battery cell. As the connection terminal, there is a series connection terminal that connects five battery cells in series. The series connection terminal and the corresponding electrode terminals of the two battery cells are brought into contact with each other, and in the contact state, the two are welded and joined. As a result, five battery cells are connected in series.

As the connection terminals, in addition to the above-mentioned series connection terminals, the output terminal 12 connected to the positive terminal of the battery cell located at the highest potential among the five battery cells connected in series, and the output terminal 12 located at the lowest potential A ground terminal 13 connected to the negative terminal of the battery cell. The output terminal 12 is welded to the positive electrode terminal of the battery cell having the highest potential. The ground terminal 13 is welded to the negative terminal of the battery cell having the lowest potential.

The highest potential battery cell and the lowest potential battery cell are included in the first battery stack. These two battery cells are located at both ends of the three battery cells stacked in the z direction in the first battery stack. The battery cell with the lowest potential is located closer to the bottom wall 93 in the z direction than the battery cell with the highest potential.

The battery case 11 has a hole through which a bolt passes. Bolt holes for fastening bolts are formed in the housing 91. A bolt is passed through these holes and the bolt hole, and the bolt is fastened to the bolt hole. As a result, the battery case 11 is fixed to the housing 91.

Further, the two suppressing plates 97 are fixed to the housing 91. The two suppression plates 97 face the housing 91 via the assembled battery 10 in the z direction. One of the two suppression plates 97 is arranged side by side in the z direction with the second battery stack. The other of the two suppressing plates 97 is arranged side by side in the z direction with the first battery stack. The two suppression plates 97 may be separated from the battery case 11 in the z direction or may be in contact with each other.

Each of the two restraint plates 97 is formed with a notch for passing a bolt. Bolt holes for fastening bolts are formed in the housing 91. A bolt is passed through the notch and the bolt hole, and the bolt is fastened to the bolt hole. As a result, the suppression plate 97 is fixed to the housing 91. The suppression plate 97 suppresses expansion of the battery case 11 due to expansion of the battery cells.

As described above, the circuit board 20 has the wiring board 21 and the BMU 22. The wiring board 21 is a printed board on which a wiring pattern made of a conductive material is formed on an insulating substrate. The first feeder line 23, the second feeder line 24, the third feeder line 25, and the fourth feeder line 26 are formed as a wiring pattern on at least one of the surface and the inside of the insulating substrate.

The wiring board 21 is fixed to the housing 91 via bolts or the like. A part of the wiring board 21 (circuit board 20) is aligned with the second battery stack in the z direction. The circuit board 20 is aligned with the battery cell having the highest potential in the x direction.

Terminals that are electrically connected to the wiring pattern are formed on the wiring board 21. The terminals include a first internal terminal 28a, a second internal terminal 28b, a third internal terminal 28c, and a fourth internal terminal 28d. The electrical connection between each of the wiring patterns and the internal terminals will be described later when the circuit configuration of the battery pack 100 is described.

The switch 30 includes a first switch 31, a second switch 32, a third switch 33, a fourth switch 34, a fifth switch 35, and a sixth switch 36. The first switch 31 and the second switch 32 are mounted on the housing 91. Each of the third switch 33 to the sixth switch 36 is mounted on the wiring board 21.

Each of the first switch 31 to the fourth switch 34 has a semiconductor switch. This semiconductor switch is specifically an N-channel MOSFET. Therefore, each of the first switch 31 to the fourth switch 34 is closed by the input of the high level control signal. Each of the first switch 31 to the fourth switch 34 is opened by the input of a low level control signal.

As the semiconductor switch included in the first switch 31 to the fourth switch 34, an IGBT or the like can be adopted. In this case, a diode is connected in parallel with the IGBT.

The fifth switch 35 and the sixth switch 36 are mechanical relays. More specifically, the fifth switch 35 and the sixth switch 36 are normally closed electromagnetic relays. Therefore, the fifth switch 35 and the sixth switch 36 are opened by the input of the high level control signal. The fifth switch 35 and the sixth switch 36 are closed by inputting a low level control signal. In other words, the fifth switch 35 and the sixth switch 36 are closed when the input of the high level control signal is interrupted.

Each of the first switch 31 to the fourth switch 34 has at least one switching unit including two MOSFETs connected in series. The source electrodes of these two MOSFETs are connected to each other. The gate electrodes of the two MOSFETs are electrically independent. The MOSFET has a parasitic diode. The anode electrodes of the parasitic diodes of the two MOSFETs are connected to each other. The gate electrode is electrically connected to the circuit board 20.

Each of the first switch 31 to the fourth switch 34 has a plurality of opening/closing sections. The plurality of opening/closing sections are connected in parallel. Then, in the third switch 33 and the fourth switch 34, the source electrodes of two series-connected MOSFETs of the plurality of opening/closing sections are connected to each other.

In the present embodiment, each of the first switch 31 to the fourth switch 34 has two opening/closing sections. The number of these opening/closing sections and the connection form such as parallel connection and series connection are appropriately determined according to the amount of current and redundancy.

The two MOSFETs included in the opening/closing section are covered with the resin section 61. The resin portion 61 has a rectangular parallelepiped shape.

As described above, the sensor unit 40 is electrically connected to the electric circuit. The sensor unit 40 has sensor elements for detecting the states of the battery pack 10 and the switch 30, respectively. The sensor unit 40 has a temperature sensor, a current sensor, and a voltage sensor as sensor elements.

The sensor unit 40 detects the temperature, current, and voltage of the assembled battery 10. The sensor unit 40 outputs it to the BMU 22 as a status signal of the assembled battery 10. In addition, the sensor unit 40 detects the temperature, current, and voltage of the switch 30. The sensor unit 40 outputs it to the BMU 22 as a status signal of the switch 30.

The temperature sensor that detects the temperature of the switch 30 is a temperature detecting diode that is covered and protected by the resin portion 61 together with the two MOSFETs connected in series. The current sensor that detects the current of the switch 30 is a shunt resistor provided between two MOSFETs connected in series.

The sensor unit 40 has a submerged sensor in addition to the various sensors described above. This submersion sensor has two counter electrodes. When water is present between the two counter electrodes, the two counter electrodes are energized. As a result, the resistance value between the two opposing electrodes changes. This change in resistance value is input to the BMU 22 as a status signal. The BMU 22 detects whether the battery pack 100 is submerged in water, based on whether or not the change in the resistance value continues for a predetermined time.

The BMU 22 controls the switch 30 based on at least one of a state signal of the sensor unit 40 and a command signal from the host ECU 160. BMU is an abbreviation for battery management unit.

As described above, each of the first switch 31 to the fourth switch 34 has a plurality of semiconductor switches. For example, when controlling the opening and closing of the first switch 31, the BMU 22 controls all semiconductor switches of the first switch 31 to be in the closed state at the same time or in the open state at the same time. For example, the BMU 22 simultaneously outputs a high level control signal or a low level control signal to the control electrodes (gate electrodes) of all the semiconductor switches included in the first switch 31.

The BMU 22 may adjust the closing time of the semiconductor switch by intermittently outputting a high-level control signal during the period in which the semiconductor switch is closed. Briefly, the BMU 22 may pulse width control the semiconductor switch.

The BMU 22 determines the state of charge (SOC) of the assembled battery 10 and the abnormality of the switch 30 based on the state signal of the sensor unit 40. SOC is an abbreviation for state of charge. The BMU 22 outputs a signal (determination information) that determines these SOC and abnormality to the host ECU 160.

The host ECU 160 determines the control of the switch 30 based on the determination information input from the BMU 22 and the vehicle information input from other various ECUs. Then, the host ECU 160 outputs a command signal including the determined control of the switch 30 to the BMU 22.

The BMU 22 controls the switch 30 based on the command signal from the host ECU 160. However, when the BMU 22 determines that the battery pack 100 is submerged in water by the state signal of the submersion sensor, the BMU 22 arbitrarily stops the output of the control signal to the switch 30. As a result, the electrical connection of the assembled battery 10 is cut off.

When the BMU 22 determines that the temperature detected by the temperature detecting diode has risen to about the operation guarantee temperature of the switch 30, the BMU 22 limits the drive of the switch 30. Similarly, when the BMU 22 determines that the current detected by the shunt resistance has risen to the operation guaranteed current of the switch 30, the BMU 22 limits the drive of the switch 30. For example, when the semiconductor switch of the switch 30 is pulse-width controlled, the BMU 22 lowers its on-duty ratio. This shortens the energization time of the semiconductor switch. As a result, heat generation of the semiconductor switch is suppressed.

The power supply bus bar 50 is made of a conductive material such as aluminum or copper. The power supply bus bar 50 can be manufactured, for example, by the methods listed below. The power supply bus bar 50 can be manufactured by bending one flat plate. The power supply bus bar 50 can be manufactured by integrally connecting a plurality of flat plates. The power supply bus bar 50 can be manufactured by welding a plurality of flat plates. The power supply bus bar 50 can be manufactured by pouring a molten conductive material into a mold. The power supply bus bar 50 can be manufactured by a manufacturing method different from the manufacturing methods listed above. However, the power supply bus bar 50 of the present embodiment is manufactured by bending one flat plate.

The battery pack 100 has a first power feeding bus bar 51, a second power feeding bus bar 52, a third power feeding bus bar 53, and a fourth power feeding bus bar 54 as the power feeding bus bar 50. The battery pack 10, the circuit board 20, the first switch 31, the second switch 32, and the external connection terminals are electrically connected by the plurality of power supply bus bars. In FIG. 1, each of these four power supply bus bars is shown thicker than the power supply line of the wiring board 21.

As described above, the housing 91 has the bottom wall 93 and the side wall 94. The bottom wall 93 has a bottom surface 93a facing the z direction. The side wall 94 stands in the z direction from the bottom surface 93a.

As shown in FIG. 2, the bottom wall 93 is provided with a first heat radiating portion 95 and a second heat radiating portion 96 which are locally projected on the cover side in the z direction. The first heat radiating portion 95 and the second heat radiating portion 96 have a rectangular parallelepiped shape on the bottom surface 93a.

The first heat dissipation portion 95 has a heat dissipation surface facing the z direction. The first switch 31 is provided on the heat radiation surface via the first heat radiation sheet 31a. The first switch 31 is bolted to the first heat radiating portion 95 in such a manner that the first heat radiating sheet 31 a is sandwiched between the first switch 31 and the first heat radiating portion 95.

Similarly, the second heat dissipation portion 96 has a heat dissipation surface facing the z direction. The second switch 32 is provided on the heat dissipation surface via the second heat dissipation sheet 32a. The second switch 32 is bolted to the second heat radiating portion 96 in such a manner that the second heat radiating sheet 32 a is sandwiched between the second switch 32 and the second heat radiating portion 96.

The battery pack 100 of this embodiment is provided below the seat of the vehicle. However, the arrangement of the battery pack 100 is not limited to this. The battery pack 100 can also be arranged, for example, in a space between a rear seat and a trunk room, a space between a driver's seat and a passenger seat, or the like.

<Battery pack circuit configuration>
Next, the circuit configuration of the battery pack 100 will be described. The precharge resistor 60 shown in FIG. 1 is also connected to this circuit. The precharge resistor 60 is mounted on the wiring board 21.

Connection between each power supply bus bar and each switch shown below is performed by TIG welding. The connection between each power supply bus bar and the circuit board 20 is made by brazing. The power supply bus bars and the switches may be connected by laser welding.

As shown in FIG. 1, the first external connection terminal 100 a and one end of the first switch 31 are electrically connected via the first power supply bus bar 51. A part of the first power supply bus bar 51 branches off. The branch portion 55 of the first power supply bus bar 51 is electrically connected to the first internal terminal 28a of the wiring board 21.

The other end of the first switch 31 and the second external connection terminal 100b are electrically connected via the second power supply bus bar 52. A part of the second power supply bus bar 52 branches off. The branch portion 56 a of the second power supply bus bar 52 is electrically connected to one end of the second switch 32. Further, the branch portion 56b is connected to the fourth internal terminal 28d.

The other end of the second switch 32 and the positive electrode of the assembled battery 10 are electrically connected via the third power feeding bus bar 53. A part is branched from the third power feeding bus bar 53. The branch portion 57 of the third power supply bus bar 53 is electrically connected to the second internal terminal 28b of the wiring board 21. The negative electrode of the assembled battery 10 is electrically connected to the third external connection terminal 100c. Specifically, the ground terminal 13 is bolted to the third external connection terminal 100c via a fuse.

The second internal terminal 28b and the first internal terminal 28a of the wiring board 21 are electrically connected via the first power supply line 23. A third switch 33 and a fourth switch 34 are serially connected to the first power supply line 23 in order from the second internal terminal 28b to the first internal terminal 28a.

The third internal terminal 28c of the wiring board 21 is electrically connected to the midpoint between the first internal terminal 28a of the first power supply line 23 and the fourth switch 34 via the second power supply line 24. The third internal terminal 28c is electrically connected to the fourth external connection terminal 100d via the fourth power supply bus bar 54.

A fifth switch 35 is provided on the second power supply line 24. The midpoint between the third internal terminal 28c and the fifth switch 35 in the second power feed line 24 is connected to the midpoint between the fourth switch 34 and the third switch 33 in the first power feed line 23. There is.

One end of the third power supply line 25 is connected to the midpoint between the first internal terminal 28 a and the fourth switch 34 of the first power supply line 23. The other end of the third power supply line 25 is connected between the connection point of the second power supply line 24 with the first power supply line 23 and the fifth switch 35. A sixth switch 36 is provided on the third power supply line 25.

One end of the fourth power supply line 26 is connected to the midpoint between the first internal terminal 28 a and the fourth switch 34 in the first power supply line 23. The other end of the fourth power supply line 26 is connected to the fourth internal terminal 28d. A precharge resistor 60 is provided on the fourth power supply line 26.

As described above, the first switch 31, the second switch 32, the third switch 33, and the fourth switch 34 are sequentially connected in a ring shape. The midpoint between the first switch 31 and the second switch 32 is connected to the second external connection terminal 100b. The midpoint between the second switch 32 and the third switch 33 is connected to the assembled battery 10. The midpoint between the third switch 33 and the fourth switch 34 is connected to the fourth external connection terminal 100d. The midpoint between the fourth switch 34 and the first switch 31 is connected to the first external connection terminal 100a.

In addition, the first external connection terminal 100 a and the fourth external connection terminal 100 d are connected via the fifth switch 35. The midpoint between the fourth switch 34 and the third switch 33 is connected to the first external connection terminal 100a via the fifth switch 35. Similarly, the first external connection terminal 100a and the fourth external connection terminal 100d are connected via the sixth switch 36. The midpoint between the fourth switch 34 and the third switch 33 is connected to the first external connection terminal 100a via the sixth switch 36.

With the electrical connection configuration described above, the electrical connection between the first external connection terminal 100a and the second external connection terminal 100b is controlled by controlling the opening/closing of the first switch 31. In other words, the electrical connection between the storage battery 110 and the rotary electric machine 130 is controlled by controlling the opening/closing of the first switch 31.

By controlling the opening/closing of the second switch 32, the electrical connection between the second external connection terminal 100b and the assembled battery 10 is controlled. In other words, the electrical connection between the rotary electric machine 130 and the assembled battery 10 is controlled by controlling the opening/closing of the second switch 32.

By controlling the opening/closing of the third switch 33, the electrical connection between the second internal terminal 28b and the third internal terminal 28c is controlled. In other words, by controlling the opening/closing of the third switch 33, the electrical connection between the battery pack 10 and the second load 152 is controlled.

By controlling the opening/closing of the fourth switch 34, the electrical connection between the first internal terminal 28a and the third internal terminal 28c is controlled. In other words, the electrical connection between the storage battery 110 and the second load 152 is controlled by controlling the opening/closing of the fourth switch 34.

By controlling opening/closing of at least one of the fifth switch 35 and the sixth switch 36, the electrical connection between the third internal terminal 28c and the first internal terminal 28a is controlled. In other words, the electrical connection between the storage battery 110 and the second load 152 is controlled by controlling the opening and closing of at least one of the fifth switch 35 and the sixth switch 36.

As described above, the connection targets of the first switch 31 to the sixth switch 36 are different. Therefore, the energization amount of each of the first switch 31 to the sixth switch 36 is different. The heat generation amounts of the first switch 31 to the sixth switch 36 are different.

In particular, the first switch 31 and the second switch 32 are electrically connected to the rotating electric machine 130. Therefore, the first switch 31 and the second switch 32 have a larger amount of energization than the other four switches, and the amount of heat generated is likely to increase. Therefore, it is necessary to suppress the temperature rise of the first switch 31 and the second switch 32. In order to solve such a problem, the first switch 31 and the second switch 32 are provided in the housing 91 having higher heat dissipation than the wiring board 21.

The first external connection terminal 100a and the second external connection terminal 100b are electrically connected via the precharge resistor 60. As described above, the second wire harness 220 is connected to the second external connection terminal 100b. A power converter (not shown) is connected to the second wire harness 220.

The power converter includes a large-capacity smoothing capacitor. The smoothing capacitor is used in the state where the electric charge is charged. The electric charge of the smoothing capacitor is charged by the power supply from the storage battery 110.

The first wire harness 210 to the third wire harness 230 are connected to the battery pack 100. As a result, electric charge is supplied from the storage battery 110 to the smoothing capacitor via the precharge resistor 60. By thus supplying power to the smoothing capacitor via the precharge resistor 60, it is possible to suppress a rapid increase in the amount of current flowing from the storage battery 110 to the smoothing capacitor.

<First switch and second switch>
As described above, the amount of heat generated by the first switch 31 and the second switch 32 is higher than that of the other four switches. And, unlike the other four switches, the first switch 31 and the second switch 32 are directly connected to the power feeding bus bar. In the following, the first switch 31 and the second switch 32 will be described in detail in order to explain the connection form with the power supply bus bar.

As described above, the first switch 31 and the second switch 32 each have two opening/closing sections connected in parallel. In order to distinguish these opening/closing sections, hereinafter, the two opening/closing sections of the first switch 31 are referred to as a first opening/closing section 60a and a second opening/closing section 60b. The two opening/closing sections of the second switch 32 are shown as a third opening/closing section 60c and a fourth opening/closing section 60d. The first opening/closing section 60a to the fourth opening/closing section 60d have the same configuration.

As shown in FIG. 3, each of the first opening/closing portion 60a to the fourth opening/closing portion 60d includes a first connecting terminal 62, a second connecting terminal 63, and a resin portion 61 in addition to the above-described two MOSFETs connected in series. , And has a control terminal 64.

One end of the first connection terminal 62 is connected to one drain terminal of the two MOSFETs. One end of the second connection terminal 63 is connected to the other drain terminal of the two MOSFETs. One end of the control terminal 64 is connected to the gate electrodes of the two MOSFETs.

The resin portion 61 covers the two MOSFETs and one end side of each of the above three terminals. The other end side of each of the three terminals is exposed from the resin portion 61.

The resin portion 61 has a flat shape with a small thickness in the z direction. The resin portion 61 has two main surfaces facing in the z direction. The resin portion 61 is formed with a through hole penetrating the two main surfaces in the z direction. A bolt is passed through this through hole.

The resin portion 61 has two side surfaces facing in the y direction. The other end side of each of the first connection terminal 62 and the second connection terminal 63 projects out from one of the two side surfaces of the resin portion 61. The other end side of the control terminal 64 projects out from the other of the two side surfaces.

The other ends of the first connection terminal 62 and the second connection terminal 63 exposed from the resin portion 61 are connected to the power supply bus bar 50. The other end of the control terminal 64 exposed from the resin portion 61 is connected to the circuit board 20.

The resin portion 61 also covers the temperature detecting diode and the shunt resistor described above. One end side of the input/output terminal of the temperature detecting diode and the detection terminal for detecting the voltage across the shunt resistor is also covered with the resin portion 61. The other end side of the input/output terminal and the detection terminal sticks out of the resin portion 61 from the other of the two side surfaces of the resin portion 61. The other ends of the input/output terminals and the detection terminals are also connected to the circuit board 20.

As shown in FIG. 3, the first opening/closing portion 60a to the fourth opening/closing portion 60d are sequentially arranged in the x direction. The other end side of each of the first connection terminal 62 and the second connection terminal 63 of each of these four opening/closing sections is lined up in the x direction. The positions of the first connection terminal 62 and the second connection terminal 63 of these four opening/closing sections are the same in the y direction and the z direction.

The first power supply bus bar 51 is connected to the first connection terminals 62 of each of the first opening/closing section 60a and the second opening/closing section 60b. The second power supply bus bar 52 is connected to the second connection terminals 63 of each of the first opening/closing section 60a and the second opening/closing section 60b. As a result, the first power feeding bus bar 51 and the second power feeding bus bar 52 are electrically connected via the first opening/closing portion 60a and the second opening/closing portion 60b.

The second power supply bus bar 52 is connected to the first connection terminals 62 of the third opening/closing part 60c and the fourth opening/closing part 60d, respectively. The third power supply bus bar 53 is connected to the second connection terminals 63 of each of the third opening/closing part 60c and the fourth opening/closing part 60d. Thus, the second power feeding bus bar 52 and the third power feeding bus bar 53 are electrically connected via the third opening/closing portion 60c and the fourth opening/closing portion 60d.

<Power supply bus bar>
As described above, the power feeding bus bar 50 has the first power feeding bus bar 51 to the fourth power feeding bus bar 54. Each of the first power feeding bus bar 51 to the fourth power feeding bus bar 54 is formed by bending a thin metal plate. The thickness direction and the extension direction of the plurality of parts forming each of the power supply bus bars are the same or different depending on the bending.

Of these four power supply bus bars, the first power supply bus bar 51 to the third power supply bus bar 53 are connected to the first switch 31 and the second switch 32. In the following, the shapes of these three power supply bus bars will be described in detail. However, the description of the connection parts of these three power supply bus bars with the circuit board 20 is omitted.

<First power supply bus bar>
As shown in the column (a) of FIG. 4, the first power feeding bus bar 51 has a first terminal portion 51a, a first main body portion 51b, and a first connecting portion 51c. The first terminal portion 51a is integrally connected to the first connecting portion 51c via the first body portion 51b.

The connecting portion between the first terminal portion 51a and the first main body portion 51b is bent. Due to this bending, the thickness direction of the first terminal portion 51a is the z direction. The thickness direction of the first main body portion 51b is the y direction. The first terminal portion 51a extends in the y direction in a manner away from the connection portion with the first main body portion 51b. The first main body portion 51b extends in the x direction in a manner away from the connection portion with the first terminal portion 51a.

A through hole penetrating in the z direction is formed in the first terminal portion 51a. The connection bolt of the first external connection terminal 100a is passed through this through hole. The first terminal portion 51a is electrically connected to the first wire harness 210 via the first external connection terminal 100a.

The thickness direction of the first connecting portion 51c is the y direction, like the first main body portion 51b. The first connecting portion 51c extends in the z direction in a manner away from the connecting portion with the first main body portion 51b.

The two first connecting portions 51c are integrally connected to the first main body portion 51b. These two first connecting portions 51c are arranged side by side in the x direction with a space therebetween. Therefore, the distance between each of the two first connecting portions 51c and the first terminal portion 51a via the first main body portion 51b is different. The energization path length between each of the two first connecting portions 51c and the first terminal portion 51a is different.

As shown in FIG. 5, the two first connecting portions 51c extend in the z direction from the first main body portion 51b toward the first switch 31. One of the two first connection parts 51c is connected to the first connection terminal 62 of the first opening/closing part 60a of the first switch 31. The other of the two first connection parts 51c is connected to the first connection terminal 62 of the second opening/closing part 60b. Note that, in FIG. 5, the first opening/closing portion 60a to the fourth opening/closing portion 60d are schematically illustrated to clearly show the connection form.

<Second power supply bus bar>
As shown in the column (b) of FIG. 4, the second power feeding bus bar 52 has a second terminal portion 52a, a second main body portion 52b, and a second connecting portion 52c. The second terminal portion 52a is integrally connected to the second connecting portion 52c via the second body portion 52b.

The connecting portion between the second terminal portion 52a and the second main body portion 52b is bent. Due to this bending, the thickness direction of the second terminal portion 52a is the z direction. The thickness direction of the second main body portion 52b is the y direction. The second terminal portion 52a extends in the y direction in a manner away from the connection portion with the second main body portion 52b. The second main body portion 52b extends in the x direction in a manner away from the connection portion with the second terminal portion 52a.

A through hole penetrating in the z direction is formed in the second terminal portion 52a. The connection bolt of the second external connection terminal 100b is passed through this through hole. The second terminal portion 52a is electrically connected to the second wire harness 220 via the second external connection terminal 100b.

The thickness direction of the second connecting portion 52c is the y direction, like the second main body portion 52b. The second connecting portion 52c extends in the z direction in a manner away from the connection portion with the second main body portion 52b.

The four second connecting portions 52c are integrally connected to the second main body portion 52b. These four second connecting portions 52c are arranged side by side in the x direction with a space therebetween. Therefore, the distance between each of the four second connecting portions 52c and the second terminal portion 52a via the second main body portion 52b is different. The conduction path length between each of the four second connecting portions 52c and the second terminal portion 52a is different.

As shown in FIG. 5, two of the four second connecting portions 52c on the side separated from the second terminal portion 52a in the x direction are moved in the z direction from the second main body portion 52b toward the first switch 31. It is extended. One of these two second connecting parts 52c is connected to the second connecting terminal 63 of the first opening/closing part 60a of the first switch 31. The other of the two second connecting parts 52c is connected to the second connecting terminal 63 of the second opening/closing part 60b.

The remaining two of the four second connecting portions 52c located on the second terminal portion 52a side extend in the z direction from the second main body portion 52b toward the second switch 32. One of these two second connection parts 52c is connected to the first connection terminal 62 of the third opening/closing part 60c of the second switch 32. The other of the two second connecting parts 52c is connected to the first connecting terminal 62 of the fourth opening/closing part 60d.

<Third feeding bus bar>
As shown in the column (c) of FIG. 4, the third power feeding bus bar 53 has a third terminal portion 53a, a third main body portion 53b, and a third connecting portion 53c. The third terminal portion 53a is integrally connected to the third connecting portion 53c via the third body portion 53b.

The connecting portion between the third terminal portion 53a and the third main body portion 53b is bent. Due to this bending, the thickness direction of the third terminal portion 53a is the z direction. The thickness direction of the third main body portion 53b is the y direction. The third terminal portion 53a extends in the y direction in a manner away from the connection portion with the third main body portion 53b. The third main body portion 53b extends in the x direction in a manner away from the connection portion with the third terminal portion 53a.

A through hole penetrating in the z direction is formed in the third terminal portion 53a. The output terminal 12 of the assembled battery 10 has a through hole penetrating in the z direction. A through hole is also formed in the bus bar case. Bolts are inserted through the through holes of the third terminal portion 53a, the output terminal 12, and the bus bar case. Then, a nut is fastened to this bolt. As a result, the third power supply bus bar 53 and the assembled battery 10 are electrically connected.

The thickness direction of the third connection portion 53c is the y direction similarly to the third main body portion 53b. The third connecting portion 53c extends in the z direction in a manner away from the connecting portion with the third main body portion 53b.

The two third connecting portions 53c are integrally connected to the third main body portion 53b. These two third connecting portions 53c are arranged side by side in the x direction with a space therebetween. Therefore, the distance between each of the two third connecting portions 53c and the third terminal portion 53a via the third main body portion 53b is different. The energization path length between each of the two third connecting portions 53c and the third terminal portion 53a is different.

As shown in FIG. 5, the two third connecting portions 53c extend in the z direction from the third main body portion 53b to the second switch 32. One of the two third connecting portions 53c is connected to the second connecting terminal 63 of the third opening/closing portion 60c of the second switch 32. The other of the two third connecting portions 53c is connected to the second connecting terminal 63 of the fourth opening/closing portion 60d.

<Arrangement of power supply bus bars>
As described above, the power feeding bus bar 50 is housed in the bus bar case. The bus bar case is formed with a plurality of groove portions for accommodating each of the first power feeding bus bar 51 to the fourth power feeding bus bar 54 individually and independently.

The first power feeding bus bar 51 to the fourth power feeding bus bar 54 are accommodated in the groove portion, and the first power feeding bus bar 51 to the third power feeding bus bar 53 are sequentially arranged in the y direction. As shown in FIG. 5, the second power feeding bus bar 52 is located between the first power feeding bus bar 51 and the third power feeding bus bar 53 in the y direction.

As described above, the other ends of the first connection terminals 62 and the second connection terminals 63 of the first opening/closing section 60a to the fourth opening/closing section 60d are arranged in the x direction. The positions of the first connecting terminal 62 and the second connecting terminal 63 of these four opening/closing portions are the same in the y direction and the z direction.

The other ends of the four first connecting terminals 62 and the second connecting terminals 63 are connected to the connecting portions of the first power feeding bus bar 51 to the third power feeding bus bar 53 in a manner to face each other in the y direction. In order to take such a connection form, at least four of the connection portions of these three power supply bus bars extend in the z direction from the main body portion, then bend in the y direction once, and extend in the z direction again. As a result, the positions in the y direction of the connection portions of the connection portions of the three power supply bus bars and the connection terminals are the same.

The first terminal portion 51a and the second terminal portion 52a are separated from each other in the x direction while the first power feeding bus bar 51 to the third power feeding bus bar 53 are sequentially arranged in the y direction. The first switch 31 and the second switch 32 are located between these two terminal portions. The first switch 31 is located on the side of the first terminal portion 51a. The second switch 32 is located on the side of the second terminal portion 52a. The first opening/closing portion 60a to the fourth opening/closing portion 60d are sequentially arranged from the first terminal portion 51a side to the second terminal portion 52a side. Due to this arrangement, the first opening/closing portion 60a is located on the first terminal portion 51a side in the x direction. The second opening/closing portion 60b is located on the second terminal portion 52a side in the x direction. In other words, the first opening/closing part 60a is located on the first external connection terminal 100a side and the second opening/closing part 60b is located on the second external connection terminal 100b side in the x direction. The x direction corresponds to the arrangement direction.

The extension directions of the first terminal portion 51a and the second terminal portion 52a in the y direction are the same. On the other hand, the extending direction of the third terminal portion 53a in the y direction is opposite to the extending direction of the first terminal portion 51a and the second terminal portion 52a in the y direction.

<Electrical path length between first external connection terminal and second external connection terminal>
Next, the energization path length between the first external connection terminal 100a and the second external connection terminal 100b via the first opening/closing part 60a and the second opening/closing part 60b will be described. As described above, the first external connection terminal 100a is connected to the first terminal portion 51a of the first power feeding bus bar 51. The second external connection terminal 100b is connected to the second terminal portion 52a of the second power supply bus bar 52. Therefore, the energization path length between the first external connection terminal 100a and the second external connection terminal 100b is equal to the energization path length between the first terminal portion 51a and the second terminal portion 52a.

The first opening/closing portion 60a corresponds to the first switch. The second opening/closing unit 60b corresponds to the second switch. The first external connection terminal 100a corresponds to the first terminal. The second external connection terminal 100b corresponds to the second terminal. The first power supply bus bar 51 corresponds to the first bus bar. The second power supply bus bar 52 corresponds to the second bus bar.

As described above, the first connecting portion 51c of the first power feeding bus bar 51 is connected to each of the first opening/closing portion 60a and the second opening/closing portion 60b. The lengths of these two first connecting portions 51c extending from the first main body portion 51b are the same. The two first connecting portions 51c have the same shape. Therefore, the electric resistances of the two first connecting portions 51c are equal to each other.

Similarly, the second connection part 52c of the second power supply bus bar 52 is connected to each of the first opening/closing part 60a and the second opening/closing part 60b. The lengths of the two second connecting portions 52c extending from the second main body portion 52b are the same. The two second connecting portions 52c have the same shape. Therefore, the electric resistances of the two second connecting portions 52c are equal to each other.

Further, as described above, the first opening/closing part 60a and the second opening/closing part 60b have the same configuration. Therefore, the first opening/closing part 60a and the second opening/closing part 60b have the same electric resistance.

Due to the relationship of the electrical resistances described above, the electrical resistance of the energizing path between the first main body portion 51b and the second main body portion 52b via the first opening/closing portion 60a and the first electrical resistance via the second opening/closing portion 60b. The electric resistances of the energizing paths between the main body portion 51b and the second main body portion 52b are equal to each other.

However, as clearly shown in FIG. 6, the first connecting portion 51c connected to the first opening/closing portion 60a and the first connecting portion 51c connected to the second opening/closing portion 60b are arranged side by side in the x direction with a space therebetween. Specifically, the first connecting portion 51c connected to the first opening/closing portion 60a is located closer to the first terminal portion 51a than the first connecting portion 51c connected to the second opening/closing portion 60b.

Therefore, the energization path length between the first connection part 51c connected to the first opening/closing part 60a and the first terminal part 51a in the first main body part 51b is equal to the first connection part connected to the second opening/closing part 60b. It is shorter than the current-carrying path length between 51c and the first terminal portion 51a. Due to the difference in the energization path length, the energization path length between the first opening/closing section 60a and the first terminal section 51a is greater than the energization path length between the second opening/closing section 60b and the first terminal section 51a. It's getting shorter.

As a result, the electric resistance of the energization path between the first opening/closing portion 60a and the first terminal portion 51a of the first power feeding bus bar 51 is the same as that of the second opening/closing portion 60b and the first terminal portion 51a of the first power feeding bus bar 51. It is lower than the electrical resistance of the energizing path between them. In other words, the electric resistance of the energization path between the first opening/closing part 60a and the first external connecting terminal 100a in the first power feeding bus bar 51 is determined by the second opening/closing part 60b and the first external connecting terminal in the first power feeding bus bar 51. It is lower than the electric resistance of the energization path to 100a.

Further, as shown in FIG. 6, the second connecting portion 52c connected to the first opening/closing portion 60a and the second connecting portion 52c connected to the second opening/closing portion 60b are also arranged side by side in the x direction. Specifically, the second connecting portion 52c connected to the first opening/closing portion 60a is farther from the second terminal portion 52a than the second connecting portion 52c connected to the second opening/closing portion 60b.

Therefore, the energization path length between the second terminal portion 52a and the second connecting portion 52c connected to the first opening/closing portion 60a in the second main body portion 52b is equal to the second connecting portion connected to the second opening/closing portion 60b. It is longer than the energization path length between 52c and the second terminal portion 52a. Due to the difference in the energization path length, the energization path length between the first opening/closing section 60a and the second terminal section 52a is greater than the energization path length between the second opening/closing section 60b and the second terminal section 52a. It's getting longer.

As a result, the electric resistance of the energization path between the first opening/closing portion 60a and the second terminal portion 52a of the second power feeding bus bar 52 is the same as that of the second opening/closing portion 60b and the second terminal portion 52a of the second power feeding bus bar 52. It is higher than the electrical resistance of the energizing path between them. In other words, the electric resistance of the energization path between the first opening/closing part 60a and the second external connection terminal 100b in the second power feeding bus bar 52 is determined by the second opening/closing part 60b in the second power feeding bus bar 52 and the second external connection terminal. It is higher than the electric resistance of the energization path between the electrode and 100b.

<Effect>
In FIG. 6, a current flowing from the first terminal portion 51a to the second terminal portion 52a via the first opening/closing portion 60a and the second opening/closing portion 60b is indicated by an arrow. It is expected that this current mainly flows along the extension direction at the centers of the first power feeding bus bar 51 and the second power feeding bus bar 52 in the thickness direction and the width direction, respectively. It is expected that the current mainly flows in the main body along the x direction at the centers of the main body in the y direction and the z direction. It is expected that the current mainly flows in the terminal portion along the z direction at the centers of the terminal portion in the y direction and the x direction.

As shown in FIG. 6, the current flows from the first terminal portion 51a to the first main body portion 51b. In the first main body portion 51b, the current flows away from the first terminal portion 51a. Then, the current is shunted toward the two first connecting portions 51c in the first main body portion 51b. These divided currents flow through the first opening/closing part 60a and the second opening/closing part 60b, respectively, and then flow to the second main body part 52b via the two second connecting parts 52c. These two electric currents merge in the second main body 52b. The merged current flows toward the second terminal portion 52a in the second body portion 52b. Then, the current flows from the second main body portion 52b to the second terminal portion 52a.

In FIG. 6, among the currents flowing from the first terminal portion 51a to the second terminal portion 52a, the currents before being divided in the first main body portion 51b and the currents after being merged in the second main body portion 52b are respectively indicated by solid arrows. Showing. The current shunting points and merging points are indicated by black circles. The current flowing through the first opening/closing part 60a is indicated by a dashed arrow. The current flowing through the second opening/closing part 60b is indicated by the alternate long and short dash line arrow.

If there is a difference in the electrical resistance of the energization path between the first terminal portion 51a and the second terminal portion 52a via the first opening/closing portion 60a and the second opening/closing portion 60b, respectively, the first opening/closing portion 60a and the second opening/closing portion A difference occurs in the amount of current flowing through the portion 60b. There is a difference in the amount of current between the current indicated by the dashed arrow shown in FIG. 6 and the current indicated by the dashed-dotted arrow.

On the other hand, in the battery pack 100, the electric resistance of the energization path between the first opening/closing portion 60a and the first terminal portion 51a of the first power feeding bus bar 51 is the same as that of the second opening/closing portion 60b of the first power feeding bus bar 51. It is lower than the electric resistance of the energization path to the 1-terminal portion 51a. At the same time, the electric resistance of the energization path between the first opening/closing portion 60a and the second terminal portion 52a of the second power feeding bus bar 52 is the same as that of the second opening/closing portion 60b and the second terminal portion 52a of the second power feeding bus bar 52. It is higher than the electrical resistance of the energizing path between them.

This may cause a difference in the electric resistance between the first terminal portion 51a and the second terminal portion 52a between the energization path via the first opening/closing part 60a and the energization path via the second opening/closing part 60b. It is suppressed. In other words, the electric resistance between the first external connection terminal 100a and the second external connection terminal 100b is different between the energization path via the first opening/closing part 60a and the energization path via the second opening/closing part 60b. It is suppressed from occurring.

Therefore, it is possible to prevent a difference in the amount of current between the current indicated by the broken line arrow flowing through the first opening/closing section 60a and the current indicated by the alternate long and short dash line flowing through the second opening/closing section 60b. Via the first power supply bus bar 51 and the second power supply bus bar 52, to the first opening/closing part 60a and the second opening/closing part 60b connected in parallel between the first external connection terminal 100a and the second external connection terminal 100b, respectively. The occurrence of bias in the amount of current flowing is suppressed.

Therefore, for example, one of the first opening/closing section 60a and the second opening/closing section 60b is suppressed from being heated to a degree exceeding the operation guarantee temperature. Due to this temperature increase, the drive of the switch 30 is suppressed from being limited by the BMU 22. Similarly, it is possible to suppress the flow of a current exceeding one of the guaranteed operation currents in one of the first opening/closing section 60a and the second opening/closing section 60b. Due to this increase in the amount of energized current, the drive of the switch 30 is suppressed from being limited by the BMU 22. As a result, it is possible to prevent the drive of the power supply system 200 from being restricted.

Further, it is possible to prevent the lifetimes of the first opening/closing section 60a and the second opening/closing section 60b from varying. It is possible to prevent the battery pack 100 from malfunctioning due to an extremely shortened life of one of the plurality of opening/closing sections. As a result, malfunction of the power supply system 200 is suppressed.

The first terminal portion 51a and the second terminal portion 52a are separated from each other in the x direction. The first switch 31 and the second switch 32 are located between the first terminal portion 51a and the second terminal portion 52a in the x direction. The first opening/closing portion 60a of the first switch 31 is located on the first terminal portion 51a side, and the second opening/closing portion 60b is located on the second terminal portion 52a side.

According to this, the increase in the energization path length between the first terminal portion 51a and the first opening/closing portion 60a in the first power feeding bus bar 51 is suppressed. In the second power supply bus bar 52, the increase in the energization path length between the second terminal portion 52a and the second opening/closing portion 60b is suppressed.

(Modification of the third power feeding bus bar)
In the present embodiment, the first power supply bus bar 51 and the second power supply bus bar 52, and the first opening/closing part 60a connected in parallel between the first external connection terminal 100a and the second external connection terminal 100b. The configuration has been shown in which unevenness in the amount of current flowing through the second opening/closing portion 60b is suppressed. As a matter of course, by adopting this configuration, the third opening/closing part 60c connected in parallel between the second external connection terminal 100b and the assembled battery 10 via the second power feeding bus bar 52 and the third power feeding bus bar 53. It is also possible to suppress the occurrence of bias in the amount of current flowing through the fourth opening/closing unit 60d.

For example, as shown in FIGS. 7 and 8, the third opening/closing portion 60c and the fourth opening/closing portion 60d of the second switch 32 are positioned between the second terminal portion 52a and the third terminal portion 53a. The connection position of the 3rd terminal part 53a with respect to the 3 main-body part 53b is determined. In this case, the third opening/closing portion 60c is located on the third terminal portion 53a side in the x direction. The fourth opening/closing portion 60d is located on the second terminal portion 52a side in the x direction. In addition, in FIG. 8, in order to clearly show the position of the third terminal portion 53a, a part of the third power feeding bus bar 53 which is not visible due to the overlapping of the second power feeding bus bar 52 is shown by a broken line.

In the case of such a configuration, the third connecting portion 53c connected to the third opening/closing portion 60c is located closer to the third terminal portion 53a than the third connecting portion 53c connected to the fourth opening/closing portion 60d. Therefore, the energization path length between the third terminal portion 53a and the third connecting portion 53c connected to the third opening/closing portion 60c in the third main body portion 53b is the third connecting portion connected to the fourth opening/closing portion 60d. It is shorter than the energization path length between 53c and the third terminal portion 53a. As a result, the electrical resistance of the energization path between the third opening/closing portion 60c and the third terminal portion 53a of the third power feeding bus bar 53 is the same as that of the fourth opening/closing portion 60d of the third power feeding bus bar 53 and the third terminal portion 53a. It is lower than the electric resistance of the energizing path between them.

The second connecting portion 52c connected to the third opening/closing portion 60c is farther from the second terminal portion 52a than the second connecting portion 52c connected to the fourth opening/closing portion 60d. Therefore, the energization path length between the second terminal portion 52a and the second connecting portion 52c connected to the third opening/closing portion 60c in the second main body portion 52b is the second connecting portion connected to the fourth opening/closing portion 60d. It is longer than the length of the energizing path between 52c and the second terminal portion 52a. As a result, the electric resistance of the energization path between the third opening/closing portion 60c and the second terminal portion 52a of the second power feeding bus bar 52 is the same as that of the fourth opening/closing portion 60d and the second terminal portion 52a of the second power feeding bus bar 52. It is higher than the electric resistance of the energizing path between them.

As a result, the electric resistance between the second terminal portion 52a and the third terminal portion 53a may differ between the energization path via the third opening/closing part 60c and the energization path via the fourth opening/closing part 60d. It is suppressed. In other words, the electric resistance between the second external connection terminal 100b and the output terminal 12 of the battery pack 10 is different between the energization path via the third opening/closing part 60c and the energization path via the fourth opening/closing part 60d. Is suppressed from occurring.

In the present embodiment, an example is shown in which the shapes and electric resistances of various parts are the same. However, in reality, due to manufacturing errors, the shapes and electric resistances of various parts are not completely equal. "Equal shape" and "equal electric resistance" mean that the shapes are equal and the electric resistance is equal within a manufacturing error range.

The cause of the difference in the amount of current flowing through the plurality of switching parts connected in parallel is not only the difference in the electric resistance of the power supply path of the power supply bus bar described above but also the characteristic variation of the semiconductor switches such as MOSFETs forming the switching part. and so on. Due to variations in the characteristics of the semiconductor switch and variations in the electric resistance of the power supply path of the power supply bus bar, the amount of current flowing through the plurality of switching units connected in parallel differs by several tens of percent. Due to such a current difference, when the battery pack 100 is used, it is a serious problem that a specific opening/closing portion of the plurality of opening/closing portions connected in parallel has a higher temperature than other opening/closing portions. It has become.

On the other hand, as described above, the difference in electrical resistance between the power supply paths of the power supply bus bars of the plurality of opening/closing sections connected in parallel is reduced. As a result, the temperature of a specific opening/closing portion among the plurality of opening/closing portions is suppressed from rising compared to the other opening/closing portions.

Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be variously modified and implemented without departing from the gist of the present disclosure.

<Equivalent circuit>
In order to simplify the description of the modified example, FIG. 9 shows a first power feeding bus bar 51 and a second power feeding bus bar 52 via the first opening/closing part 60a and the second opening/closing part 60b shown in FIG. An energization path between the two is schematically shown. In this schematic diagram, the path length of the energizing path is proportional to the electrical resistance. A broken line is given to the boundary between the main body portion and the connection portion. Each of the first connection terminal 62 and the second connection terminal 63 is shown thicker than the line showing the energization path.

(First modification)
FIG. 10 shows a modification of the power feeding bus bar 50 according to the schematic diagram shown in FIG. In this modification, the first switch 31 includes three opening/closing sections. The first opening/closing portion 60a, the second opening/closing portion 60b, and the fifth opening/closing portion 60e are arranged in order in the x direction.

In this modification, the electrical resistance of the energization path between the first opening/closing part 60a and the first external connection terminal 100a is greater than the electrical resistance of the energization path between the second opening/closing part 60b and the first external connection terminal 100a. Is also low. The electrical resistance of the energizing path between the second opening/closing part 60b and the first external connecting terminal 100a is lower than the electrical resistance of the energizing path between the fifth opening/closing part 60e and the first external connecting terminal 100a. ..

Further, the electrical resistance of the energization path between the first opening/closing part 60a and the second external connection terminal 100b is higher than the electrical resistance of the energization path between the second opening/closing part 60b and the second external connection terminal 100b. ing. The electrical resistance of the energizing path between the second opening/closing part 60b and the second external connecting terminal 100b is higher than the electrical resistance of the energizing path between the fifth opening/closing part 60e and the second external connecting terminal 100b. ..

Therefore, when the electric resistance of the energization path between the first external connection terminal 100a and the second external connection terminal 100b passes through the first opening/closing part 60a, the second opening/closing part 60b, and the fifth opening/closing part 60e. The difference is suppressed. It should be noted that this action and effect also occurs when the first switch 31 includes four or more opening/closing sections. In this way, it is possible to suppress the occurrence of a difference in the electric resistance of the current-carrying path between the two terminals via any two opening/closing sections among the three or more opening/closing sections.

(Second modified example)
Further, FIG. 11 shows a modified example in which the extension direction of the first main body portion 51b is changed. In this modification, the first terminal portion 51a and the second terminal portion 52a are located on the second opening/closing portion 60b side of the first opening/closing portion 60a and the second opening/closing portion 60b. The first main body portion 51b extends in the x direction in a state of being separated from the first terminal portion 51a, then bends, and extends in the x direction toward the first terminal portion 51a side. The first connecting portion 51c is integrally connected to a portion of the first main body portion 51b that is returned to the first terminal portion 51a side and extends in the x direction.

Also in such a modified example, the electric resistance of the energization path between the first opening/closing part 60a and the first external connection terminal 100a is equal to that of the energization path between the second opening/closing part 60b and the first external connection terminal 100a. It is lower than the electrical resistance. The electrical resistance of the energization path between the first opening/closing part 60a and the second external connection terminal 100b is higher than the electrical resistance of the energization path between the second opening/closing part 60b and the second external connection terminal 100b. .. Therefore, the electric resistance of the energization path between the first external connection terminal 100a and the second external connection terminal 100b is different between when the first opening/closing portion 60a is interposed and when the second opening/closing portion 60b is interposed. Is suppressed. As a result, the same operational effects as the operational effects shown in the present embodiment are produced.

This action and effect can be obtained even when the first switch 31 includes three opening/closing portions as shown in FIG. 12, for example. As a matter of course, this action and effect also occurs when the first switch 31 includes four or more opening/closing sections.

(Third Modification)
In the present embodiment, since there is a difference in the current-carrying path length between each of the plurality of opening/closing sections and one terminal, there is a difference in the electrical resistance of the current-carrying path between each of the plurality of opening/closing sections and one terminal. There is an example. However, for example, a local notch may be formed in the power feeding bus bar, or the thickness may be locally increased, so that the power feeding bus bar may locally have a portion having a different electric resistance. The plurality of power supply bus bars may have different thicknesses and widths. Since the average electric resistance per unit length in the energization path of each of the plurality of power supply busbars is different, a configuration is adopted in which the electric resistance of the energization path between each of the plurality of opening/closing sections and one terminal section is different. You can also In the case of such a configuration, there is no need to make a difference in the energization path length between each of the plurality of opening/closing sections and one terminal section.

(Fourth Modification)
The element connected in parallel between the two power supply bus bars is not limited to the one in which two semiconductor switches are connected in series like an opening/closing section. It is also possible to adopt a configuration in which one semiconductor switch or a switch including one mechanical relay is connected in parallel between two power supply bus bars.

(Other modifications)
In each embodiment, the example in which the battery pack 10 has five battery cells is shown. However, the assembled battery 10 is not limited to the above example as long as it has a plurality of battery cells. Further, the number of battery stacks may be one or three or more instead of two. Further, the battery stack may be configured by arranging the battery cells in the x direction.

In each embodiment, the example in which the vehicle equipped with the power supply system 200 has the idle stop function is shown. However, the vehicle equipped with the power supply system 200 is not limited to the above example. For example, a hybrid vehicle or an electric vehicle can be adopted. In this case, the starter motor 120 and the rotary electric machine 130 shown in the present embodiment replace the motor generator.

10... Assembly battery, 12... Output terminal, 30... Switch, 51... 1st electric power feeding bus bar, 52... 2nd electric power feeding bus bar, 53... 3rd electric power feeding bus bar, 60a... 1st opening/closing part, 60b... 2nd opening/closing part, 60c ... 3rd opening/closing part, 60d... 4th opening/closing part, 60e... 5 opening/closing part, 100a... 1st external connection terminal, 100b... 2nd external connection terminal, 110... Storage battery, 120... Starter motor, 130... Rotating electric machine, 150 …Electrical load, 160…Upper ECU, 200…Power supply system

Claims (4)

A battery (10),
A plurality of switches (60a-60e) electrically connected in parallel between a first terminal (100a, 12) and a second terminal (100b) electrically connected to the battery;
A first bus bar (51, 53) connecting each of the plurality of switches and the first terminal;
A second bus bar (52) connecting each of the plurality of switches and the second terminal,
When any two of the plurality of switches are the first switch and the second switch,
The electrical resistance of the conduction path between the first switch and the first terminal in the first bus bar is higher than the electrical resistance of the conduction path between the second switch and the first terminal in the first bus bar. Low,
The electrical resistance of the energizing path between the first switch and the second terminal in the second bus bar is higher than the electrical resistance of the energizing path between the second switch and the second terminal in the second bus bar. High battery pack. An energization path length between the first switch and the first terminal in the first bus bar is shorter than an energization path length between the second switch and the first terminal in the first bus bar,
The energization path length between the first switch and the second terminal in the second bus bar is longer than the energization path length between the second switch and the second terminal in the second bus bar. The battery pack described in. A plurality of the switches are arranged in a line direction,
The first terminal and the second terminal are arranged side by side in the arrangement direction at a distance from each other,
A plurality of the switches are located between the first terminal and the second terminal in the arrangement direction,
The first switch is located closer to the first terminal than the second switch in the alignment direction, and the second switch is located closer to the second terminal than the first switch. The battery pack according to Item 2. A plurality of the switches are arranged in a line direction,
The first terminal and the second terminal are located on one side of the switches located on two end sides of the plurality of switches arranged in the arranging direction. Battery pack described.

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