JPWO2014068895A1 - In-vehicle battery system - Google Patents

Abstract

Provided is a technique for improving the charge / discharge efficiency of a power storage unit in an in-vehicle battery system. An in-vehicle battery system (1) according to an aspect includes a lead storage battery, a first power storage module (10) including a first housing (14) for housing the lead storage battery, and the first power storage module (10). A power storage unit disposed and having a higher energy density than the lead storage battery, and a second power storage module (20) including a second housing (24) that houses the power storage unit. The second housing (24) is disposed on the first portion (24a) disposed on the first power storage module (10) side and on the side farther from the first power storage module (10) than the first portion (24a). Second portion (24b). The first portion (24a) is made of a material having higher thermal conductivity than the second portion (24b).

Description

  The present invention relates to an in-vehicle battery system.

  In general, a vehicle using an internal combustion engine as a drive source is equipped with a lead storage battery that supplies power to various electric loads such as a starter motor. Lead storage batteries are less expensive than high performance, high energy storage batteries such as nickel storage batteries and lithium ion storage batteries, but have low durability against frequent charging and discharging. Particularly in a vehicle having an idle stop function, the lead storage battery is frequently discharged, and there is a concern about early deterioration. In addition, when the alternator is generated and charged by the regenerative energy of the vehicle, the lead storage battery is frequently charged, so that early deterioration is further concerned. In response to these concerns, simply replacing the lead-acid battery with a high-performance battery results in a significant cost increase.

  On the other hand, a generator such as an alternator, a lead storage battery capable of charging the power generated by the generator, and electrically connected to the lead storage battery in parallel to be able to charge the power generated by the generator, and An in-vehicle battery device including a second storage battery having a higher output density or energy density than a lead storage battery is known (see Patent Document 1). Thus, by providing the 2nd storage battery which is a high performance storage battery in addition to a lead storage battery, coexistence with suppression of deterioration of a lead storage battery and cost reduction can be aimed at. That is, for example, power supply to an electric load or regenerative charging during an idle stop is performed preferentially by a high-performance storage battery, so that deterioration of the lead storage battery can be reduced. On the other hand, power supply required for a long time, such as when a vehicle is parked, is preferentially implemented by an inexpensive lead storage battery, so that the capacity of the high performance storage battery can be reduced and the cost increase can be suppressed. .

JP 2011-176958 A

  As a result of diligent research, the present inventors have found that there is room for improvement in the conventional in-vehicle battery system including a lead storage battery and a power storage unit as an auxiliary power source in order to improve the charge / discharge efficiency of the power storage unit. I found.

  This invention is made | formed in view of such a condition, The objective is to provide the technique which aims at the improvement of the charging / discharging efficiency of the electrical storage part in a vehicle-mounted battery system.

  One embodiment of the present invention is an in-vehicle battery system. The in-vehicle battery system includes a lead storage battery, a first power storage module including a first housing that houses the lead storage battery, and a power storage that is disposed adjacent to the first power storage module and has a higher energy density than the lead storage battery. And a second power storage module including a second housing that houses the power storage unit. The second housing includes a first portion disposed on the first power storage module side and a second portion disposed on a side farther from the first power storage module than the first portion. The first portion is made of a material having higher thermal conductivity than the second portion.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which aims at the improvement of the charging / discharging efficiency of the electrical storage part in a vehicle-mounted battery system can be provided.

1 is a perspective view schematically showing an in-vehicle battery system according to Embodiment 1. FIG. It is a perspective view which shows a 2nd electrical storage module typically. 1 is an electrical block diagram including an in-vehicle battery system according to Embodiment 1. FIG. It is sectional drawing along the AA in FIG. 6 is a cross-sectional view schematically showing a second power storage module of the in-vehicle battery system according to Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

(Embodiment 1)
First, the basic knowledge will be described before the present embodiment is specifically described. The present inventor has come up with the idea that the power storage unit is installed in the engine room of the vehicle together with the lead storage battery in a vehicle battery system including a lead storage battery and a power storage unit having a high-performance storage battery. By arranging the power storage unit in the engine room, for example, when the power storage unit is installed in the vehicle's living space, the living space is narrowed and the wiring connection with the alternator or lead storage battery as a generator is complicated. Can be suppressed. Also, with this configuration, the power storage unit can be arranged near the alternator and the wiring can be made relatively short, so that electrical loss due to wiring resistance can be reduced. However, since the engine room is in a relatively high temperature environment, when the power storage unit is disposed in the engine room, the temperature of the power storage unit may increase, and the charge / discharge efficiency of the power storage unit may decrease. In particular, in the configuration in which the power storage unit is disposed in the engine room, even if the cooling air is sent to the power storage unit by the blower fan, the cooling power is high temperature, and therefore the power storage unit cannot be efficiently cooled. There is a fear. Based on such knowledge, the present applicant has developed an in-vehicle battery system according to the present embodiment.

  FIG. 1 is a perspective view schematically showing the in-vehicle battery system according to the first embodiment. FIG. 2 is a perspective view schematically showing the second power storage module. FIG. 3 is an electric block diagram including the in-vehicle battery system according to the first embodiment. 4 is a cross-sectional view taken along line AA in FIG. In FIGS. 2 and 4, some of the wirings are not shown, and the internal structure of the second power storage module is indicated by a broken line. Moreover, in FIG. 4, illustration of the internal structure of the storage battery which comprises an electrical storage part is abbreviate | omitted.

  The on-vehicle battery system according to Embodiment 1 is a battery system mounted on a vehicle using an internal combustion engine as a drive source. It is preferable that the vehicle has an idling stop function in which the internal combustion engine automatically stops when the vehicle stops, and the internal combustion engine restarts when a starting operation such as releasing the brake pedal is performed.

  As shown in FIGS. 1 and 2, the in-vehicle battery system 1 according to the present embodiment includes a first power storage module 10 and a second power storage module 20. The first power storage module 10 includes a lead storage battery 12 (see FIG. 3) and a first housing 14 that houses the lead storage battery 12. The lead storage battery 12 is a conventionally known lead storage battery in which cells of known lead storage batteries are housed in a case, and the structure thereof is not particularly limited. Specifically, in the single cell constituting the lead storage battery 12, lead is used as the negative electrode active material, lead dioxide is used as the positive electrode active material, and sulfuric acid is used as the electrolytic solution. The lead storage battery 12 is configured by electrically connecting a plurality of the single cells in series.

  The second power storage module 20 includes a power storage unit 22 having a higher energy density (Wh / kg) than the lead storage battery 12 and a second housing 24 that houses the power storage unit 22. A battery having a high energy density such as the power storage unit 22 stores high energy in a relatively small housing. Therefore, it has the characteristic that heat dissipation is low compared with a battery with low energy density.

  The power storage unit 22 is constituted by, for example, a lithium ion storage battery or a hydrogen battery. For example, when the storage battery constituting the power storage unit 22 is a lithium ion storage battery, the storage battery may be a cell structure of a known lithium ion storage battery, and is not particularly limited. For example, in a single cell constituting a lithium ion storage battery, a lithium metal oxide such as lithium cobaltate is used as a positive electrode active material, a carbon material such as carbon is used as a negative electrode active material, and an organic solution such as ethylene carbonate or propylene carbonate is used as an electrolyte. An electrolyte is used. A lithium ion storage battery is configured by electrically connecting a plurality of such single cells in series. The power storage unit 22 of the present embodiment is composed of ten cylindrical storage batteries 23. In addition, the number, shape, and arrangement of the storage battery 23 are not particularly limited. For example, the shape of the storage battery 23 may be rectangular.

  Each storage battery 23 is electrically connected in series with each other by a wiring 26 and is accommodated in the second housing 24. A part of the wiring 26 is exposed at the upper part of the second housing 24 to form a negative electrode terminal 28a. In addition, a part of the wiring 26 is exposed at the upper part of the second housing 24 to form a positive electrode terminal 28b. A through-hole 30 through which a fastening member (not shown) such as a screw is inserted is provided in the peripheral portion of the second housing 24. The second power storage module 20 is fixed to the first power storage module 10 by inserting the fastening member through the through hole 30. In addition, the fixing method of the 1st electrical storage module 10 and the 2nd electrical storage module 20 is not specifically limited to this.

  As shown in FIG. 3, the lead storage battery 12 and the power storage unit 22 of the in-vehicle battery system 1 are electrically connected to an alternator 230 (power generation unit) that converts regenerative energy into electric power, a starter motor 240, and a vehicle-side electrical unit 250. Connected in parallel. In addition, the vehicle battery system 1 includes a voltage detection circuit 122, a CPU 124, and a control circuit 126. The 1st electrical storage module 10, the 2nd electrical storage module 20, and the alternator 230 are arrange | positioned in the engine room 102 of a vehicle. Voltage detection circuit 122 detects the voltage of power storage unit 22. The CPU 124 instructs the control circuit 126 to turn on and off the switches (switches 90 and 92) according to the voltage detected by the voltage detection circuit 122 and the driving situation of the vehicle. The control circuit 126 turns on and off the switches in accordance with instructions from the CPU 241. For example, the voltage detection circuit 122, the CPU 124, and the control circuit 126 are incorporated in the second power storage module 20.

  The switch 90 is installed between a branch point A1 between the power storage unit 22 and the vehicle-side electrical unit 250 and a branch point A2 between the lead storage battery 12 and the alternator 230. Energization and interruption between the power storage unit 22 and the alternator 230 are switched. The switch 92 is provided between the branch point A <b> 1 and the power storage unit 22, and energization and disconnection between the power storage unit 22, the switch 90, and the vehicle-side electrical unit 250 are switched by turning on / off the switch 92.

  Alternator 230 converts the rotational energy of the crankshaft into electric power. The starter motor 240 is a motor that rotates the crankshaft when the internal combustion engine is started. The starter motor 240 is connected to a branch point A3 between the branch point A2 and the alternator 230. A switch 94 is provided between the branch point A3 and the starter motor 240. By turning on and off the switch 94, energization and shutoff from the lead storage battery 12 or the power storage unit 22 to the starter motor 240 are switched. On / off of the switch 94 is controlled by an ECU (not shown).

  The vehicle-side electrical unit 250 is a general electric device such as a navigation system, an audio device, or the like that requires a stable power supply voltage, such as an electrical load, a headlight, a wiper, or a blower fan for an air conditioner. It is a load.

(During regenerative charging)
When charging the lead storage battery 12 and the power storage unit 22 with regenerative energy generated when the vehicle is decelerated, the switch 90 is turned on. The lead storage battery 12 is sequentially charged while regenerative energy is generated, and is kept in a state close to full charge. On the other hand, when the voltage of the power storage unit 22 detected by the voltage detection circuit 122 is lower than a predetermined lower limit voltage, the switch 92 is turned on, and the power storage unit 22 is charged while the switch 92 is turned on. The During the charging operation using regenerative energy, the switch 94 is turned off and the starter motor 240 is disconnected from the discharge / charge circuit.

(Normal discharge)
During engine operation other than the charging operation using regenerative energy described above, both the switch 90 and the switch 94 are turned off. On the other hand, when the voltage of power storage unit 22 detected by voltage detection circuit 122 is equal to or higher than a predetermined lower limit voltage, switch 92 is turned on and the power of power storage unit 22 is supplied to vehicle-side electrical unit 150.

(During idle stop and starter motor operation)
The switch 94 is turned on and the switch 90 is turned off during idle stop when the engine is automatically stopped and when the starter motor is activated when the engine is started. Further, the switch 92 is turned on. Thereby, power storage unit 22 and vehicle-side electrical unit 250 are disconnected from alternator 230 and starter motor 240, and discharge from power storage unit 22 to starter motor 240 is prevented. In this state, when the voltage of the power storage unit 22 detected by the voltage detection circuit 122 is equal to or higher than a predetermined lower limit voltage, the switch 92 is turned on, and the power of the power storage unit 22 is supplied to the vehicle-side electrical unit 250. The

  Then, the structure of the 2nd housing | casing 24 of the 2nd electrical storage module 20 is demonstrated in detail. As shown in FIGS. 1, 2, and 4, the second power storage module 20 is disposed adjacent to the first power storage module 10. And the 2nd housing | casing 24 of the 2nd electrical storage module 20 is the 1st part 24a arrange | positioned at the 1st electrical storage module 10 side, and the 1st part arrange | positioned in the side far from the 1st electrical storage module 10 rather than the 1st part 24a. And two portions 24b. In the present embodiment, each of the first portion 24a and the second portion 24b has a flat rectangular parallelepiped shape, and is disposed so that the main surfaces of each of the first portion 24a and the second portion 24b are in contact with each other, and the second casing 24 is formed. Therefore, the second casing 24 has a flat rectangular parallelepiped shape, and one main surface and a part of the side surface thereof are constituted by the first portion 24a, and the other main surface and the remaining part of the side surface are constituted by the second portion 24b. Is done.

  On the main surface of the first portion 24a on the side in contact with the second portion 24b, a number of recesses 32a corresponding to the storage battery 23 constituting the power storage unit 22 is provided. In addition, the number of recesses 32b corresponding to the storage battery 23 is provided on the main surface of the second portion 24b on the side in contact with the first portion 24a. The concave portion 32a and the concave portion 32b are arranged so as to face each other in a state where the first portion 24a and the second portion 24b are in contact with each other, and a housing space for the storage battery 23 is formed by the concave portion 32a and the concave portion 32b.

  The first portion 24a of the second housing 24 is made of a material having higher thermal conductivity than the second portion 24b. That is, the first part 24a has higher heat dissipation than the second part 24b, and the second part 24b has higher heat insulation than the first part 24a. Examples of the material constituting the second portion 24b include polycarbonate, polypropylene, and a phenol resin.

  As a material constituting the first portion 24a, for example, a resin filled with a filler having high thermal conductivity can be used. As such a material, for example, a resin that is a constituent material of the second portion 24b described above and filled with a metal filler such as copper or aluminum can be cited. In addition, it is preferable that the material which comprises the 1st part 24a is a material which can ensure the insulation between the lead storage battery 12 and the electrical storage part 22. FIG. The thermal conductivity can be measured by a conventionally known method such as a laser flash method.

  In the present embodiment, the first portion 24 a having a high heat dissipation property is disposed on the side closer to the first power storage module 10 than the power storage unit 22, and the first heat insulating property is higher on the side farther from the first power storage module 10 than the power storage unit 22. Two portions 24b are arranged.

  In this way, by making the heat dissipation of the first portion 24a disposed on the side closer to the first power storage module 10 higher than the heat dissipation of the second portion 24b disposed on the side far from the first power storage module 10. The heat generated by charging / discharging of the power storage unit 22 can be efficiently transmitted to the first power storage module 10 via the first portion 24a. The first power storage module 10 has a relatively large heat capacity. Therefore, the cooling efficiency of the 2nd electrical storage module 20 is improved by arrange | positioning the 1st part 24a with high heat dissipation in the 1st electrical storage module 10 side, and utilizing the 1st electrical storage module 10 for cooling of the electrical storage part 22. Can do.

  On the other hand, by making the heat insulating property of the second part 24b arranged on the side far from the first power storage module 10 higher than the heat insulating property of the first part 24a arranged on the side close to the first power storage module 10, external Heat transfer from the environment to the power storage unit 22 can be suppressed. In particular, when the in-vehicle battery system 1 is disposed in the engine room 102, the inside of the engine room 102 is relatively hot. Therefore, the temperature rise of the electrical storage part 22 can be suppressed by arrange | positioning the 2nd part 24b with high heat insulation in the side far from the 1st electrical storage module 10, ie, the atmosphere side of the engine room 102. FIG.

  It is preferable that at least a part of the first portion 24 a is in direct contact with the first power storage module 10. In the second power storage module 20 of the present embodiment, the entire one main surface of the second housing 24 configured by the first portion 24 a is in direct contact with the first power storage module 10. Since the first portion 24 a is in direct contact with the first power storage module 10, the heat generated in the power storage unit 22 can be easily transferred by the first power storage module 10. Moreover, in the vehicle-mounted battery system 1 of this embodiment, the 1st electrical storage module 10 is a rectangular parallelepiped shape, and the whole main surface of the 2nd housing | casing 24 is in contact with the whole one main surface of the 1st electrical storage module 10. FIG. . That is, the area of the main surface of the 1st electrical storage module 10 and the area of the main surface of the 2nd housing | casing 24 correspond. Thereby, the utilization efficiency of the 1st electrical storage module 10 as a cooling medium of the electrical storage part 22 can be improved.

  Note that at least a portion of the first portion 24a may be in contact with the first power storage module 10 via another member having higher thermal conductivity than the second portion 24b. Also in this case, compared to the case where the power storage unit 22 and the second housing 24 are arranged with a space therebetween, or when the entire surface of the second housing 24 is configured by the second portion 24b, The heat of the power storage unit 22 can be easily transmitted to the first power storage module 10.

  Of the surface of the second housing 24, it is preferable that an unevenness is provided in a region in contact with the first power storage module 10. By providing irregularities on the surface of the second housing 24, the contact area between the first power storage module 10 and the second housing 24 can be increased. As a result, the cooling efficiency of the power storage unit 22 can be further increased.

  As described above, in the in-vehicle battery system 1 according to the present embodiment, the second power storage module 20 includes the second housing 24 including the first portion 24a and the second portion 24b. The first portion 24a is disposed on the first power storage module 10 side, and the second portion 24b is disposed on the side farther from the first power storage module 10 than the first portion 24a. And the 1st part 24a is comprised with the material whose heat conductivity is high compared with the 2nd part 24b. That is, the surface of the second housing 24 that is in contact with the first power storage module 10 is configured by the first portion 24a having high heat dissipation, and at least part of the surface of the second housing 24 that is not in contact with the first power storage module 10 is It is comprised by the 2nd part 24b with high heat insulation.

  Accordingly, the first power storage module 10 having a large heat capacity can be efficiently used for cooling the power storage unit 22 of the second power storage module 20. Therefore, the temperature rise of power storage unit 22 can be suppressed and the charge / discharge efficiency of power storage unit 22 can be increased. Further, even when the in-vehicle battery system 1 is placed in a high temperature environment such as the engine room 102, heat transfer from the outside to the inside of the second power storage module 20 can be suppressed. Therefore, it is possible to suppress a decrease in charge / discharge performance of power storage unit 22 due to a temperature rise. And as a result, stabilization of the charging / discharging performance of the vehicle-mounted battery system 1 can be achieved. Moreover, since the temperature range which can use the vehicle-mounted battery system 1 can be expanded, the installation freedom degree of the vehicle-mounted battery system 1 can be raised. In addition, since the first power storage module 10, the second power storage module 20, and the alternator 230 are disposed in the engine room 102, for example, compared with a configuration in which the second power storage module 20 is disposed outside the engine room 102, The wiring to be connected can be shortened. Thereby, electrical loss due to wiring resistance can be reduced.

(Embodiment 2)
The in-vehicle battery system according to the second embodiment is common to the configuration of the in-vehicle battery system according to the first embodiment except that the shapes of the first part and the second part of the second housing are different. Hereinafter, the vehicle battery system according to the second embodiment will be described focusing on the configuration different from the first embodiment.

  FIG. 5 is a cross-sectional view schematically showing a second power storage module of the in-vehicle battery system according to the second embodiment. In FIG. 5, illustration of a part of the wiring is omitted, and the internal structure of the second power storage module is illustrated by a broken line. Moreover, illustration of the internal structure of the storage battery which comprises an electrical storage part is abbreviate | omitted.

  In the in-vehicle battery system 1 according to the present embodiment, the second housing 24 of the second power storage module 20 includes a first portion 24a disposed on the first power storage module 10 side and a first power storage than the first portion 24a. And a second portion 24b disposed on the side far from the module 10. In the present embodiment, a flat plate portion 24b1 in which the second portion 24b is a flat rectangular parallelepiped shape, and a frame portion 24b2 protruding in a direction perpendicular to the main surface from the peripheral portion of one main surface of the flat plate portion 24b1. Have. An accommodation space 34 of the first portion 24a is formed by the central portion of one main surface of the flat plate portion 24b1 and the inner peripheral surface of the frame portion 24b2. The first portion 24a has a flat rectangular parallelepiped shape that is slightly smaller than the second portion 24b, and is accommodated in the accommodation space 34 of the second portion 24b. In a state of being accommodated in the accommodation space 34, the side surface of the first portion 24a abuts on the inner peripheral surface of the frame portion 24b2.

  Therefore, the second casing 24 has a flat rectangular parallelepiped shape, and one main surface and side surfaces thereof are constituted by the second portion 24b. Moreover, the peripheral part of the other main surface is comprised by the 2nd part 24b, and the remaining part is comprised by the 1st part 24a. And the 2nd electrical storage module 20 is arrange | positioned so that the main surface of the 2nd housing | casing 24 by which the 1st part 24a is exposed faces the 1st electrical storage module 10 side (refer FIG. 1). Therefore, in the 2nd electrical storage module 20 of this embodiment, the surface of the 2nd housing | casing 24 is comprised by the 2nd part 24b except the area | region which contact | connects the 1st electrical storage module 10. FIG. In other words, the entire surface of the second casing 24 that is exposed to the external atmosphere is configured by the second portion 24b.

  Thereby, compared with Embodiment 1 with which a part of side surface of the 2nd housing | casing 24 comprises the 1st part 24a, the transmission of the heat | fever from the exterior to the electrical storage part 22 can be suppressed further. Therefore, the charge / discharge performance of the power storage unit 22 can be further prevented from being lowered, and the charge / discharge performance of the in-vehicle battery system 1 can be further stabilized.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art, and the embodiments to which such modifications are added are also possible. It can be included in the scope of the present invention. Moreover, what combined suitably each element of each embodiment mentioned above can also be contained in the scope of the present invention.

  In each above-mentioned embodiment, although the electrical storage part 22 has the storage battery 23, it is not limited to this in particular. For example, the power storage unit 22 may be a capacitor (capacitor) such as an electric double layer capacitor. Moreover, although the vehicle-mounted battery system 1 of each above-mentioned embodiment does not include the alternator 230 as a power generation unit in its configuration, it is not particularly limited to this. For example, the in-vehicle battery system 1 may include the alternator 230 as a configuration.

  DESCRIPTION OF SYMBOLS 1 Vehicle-mounted battery system, 10 1st electrical storage module, 12 Lead storage battery, 14 1st housing | casing, 20 2nd electrical storage module, 22 Electrical storage part, 24 2nd housing | casing, 24a 1st part, 24b 2nd part

Claims (6)

A first storage module including a lead storage battery and a first housing for housing the lead storage battery;
A second power storage module including a second power storage unit disposed adjacent to the first power storage module and having a higher energy density than the lead storage battery, and a second housing that houses the power storage unit;
With
The second housing includes a first portion disposed on the first power storage module side, and a second portion disposed on a side farther from the first power storage module than the first portion,
The in-vehicle battery system, wherein the first portion is made of a material having higher thermal conductivity than the second portion.   The in-vehicle battery system according to claim 1, wherein at least a part of the first portion is in contact with the first power storage module directly or via another member having higher thermal conductivity than the second portion.   The in-vehicle battery system according to claim 2, wherein the surface of the second casing is configured by the second portion except for a region in contact with the first power storage module directly or via the other member.   The in-vehicle battery system according to any one of claims 1 to 3, wherein the lead storage battery and the power storage unit are electrically connected in parallel to a power generation unit that converts regenerative energy into electric power.   The in-vehicle battery system according to claim 4, further comprising the power generation unit that converts regenerative energy into electric power and charges the lead storage battery and the power storage unit.   The on-vehicle battery system according to claim 4 or 5, wherein the first power storage module, the second power storage module, and the power generation unit are disposed in an engine room of a vehicle.

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