Power supply device and vehicle

A power supply device to be mounted on a vehicle includes a battery module, a power storage casing for accommodating the battery module, a DC/DC converter stepping down an output voltage of the battery module to a first voltage and a DC/DC converter stepping down the output voltage of the battery module into a second voltage. The battery module, DC/DC converter and DC/DC converter are fixed to the power storage casing. This structure provides the power supply device of small sizes capable of supplying electricity of three or more kinds of voltages.

CROSS REFERENCE TO RELATED APPLICATION

This application is a National Stage of International Application No. PCT/JP2007/062071 filed Jun. 8, 2007, claiming priority based on Japanese Patent Application No. 2006-164964, filed Jun. 14, 2006, the contents of all of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a power supply device and a vehicle with the power supply device.

BACKGROUND ART

In recent years, electric vehicles using an electric motor as a drive source as well as so-called hybrid electric vehicles using a combination of an electric motor and another type of drive source such as an internal combustion engine or a fuel cell have been practically available. This kind of vehicle is provided with a power storage unit for supplying electricity, i.e., energy to the electric motor. A repetitively chargeable secondary battery, a capacitor or the like is arranged as the power storage unit.

A nickel cadmium battery, a nickel hydrogen battery or a lithium ion battery is used as the secondary battery. The secondary battery includes, e.g., a battery module having layered battery cells. The battery module is mounted on the vehicle together with a power storage casing accommodating it. The battery module supplies a DC power. Since the secondary battery mounted on the vehicle is required to provide a high voltage and a high output, it is formed of about thirty battery modules connected in series. Each battery cell is formed of about six cells connected in series and each having an output of about 1.2 V. This battery module achieves a high input/output voltage.

The motor providing a drive power of the vehicle is driven by an AC power. DC electricity provided from the power storage unit is converted into AC electricity, which is fed to the motor. The power supply device may be connected to control units and/or auxiliary devices such as an audio unit in addition to the inverter for driving the motor. These units and devices are driven with a low voltage. Therefore, the power supply device may be provided with a converter for stepping down the voltage of the power storage unit.

Japanese Patent Laying-Open No. 2004-114821 has disclosed a power supply package having power supply parts of a 42-V system and power supply parts of a 14-V system that are arranged and integrated in a package casing to be arranged in an engine room of a vehicle. In this power supply package, all power supply interconnections for mutual connection between power supply parts or for external connection thereof are formed of bus bars, and the bus bars of the power supply parts can be connected together only by sliding these parts in the attaching direction. According to the disclosure, this power supply package can provide a wiring-less structure, and can facilitate mounting and wiring operations. Also, according to the disclosure, the power supply package includes an inverter, a DC/DC converter, a 36-V battery, a 12-V battery and others that are arranged in the package casing, and are accommodated in the engine room of the vehicle together with the package casing.

Japanese Patent Laying-Open No. 2004-106807 has disclosed a hybrid vehicle having a high-potential battery supplying an electric power to a drive motor driving a vehicle as well as a low-potential battery supplying an electric power to auxiliary devices of the vehicle. The high-potential battery is formed of a plurality of divided battery units, and the divided battery units of the high-potential battery as well as the low-potential battery are arranged behind a rearmost seat of the vehicle, and are located in spaced two positions that neighbor to sidewalls of a vehicle body, respectively. According to the disclosure, this hybrid vehicle can achieve a good balance in vehicle weight, a flat baggage compartment and a trunk-through structure.

Japanese Patent Laying-Open No. 2005-297860 has disclosed a power supply device for a vehicle and particularly for a hybrid vehicle that uses in combination a high-voltage battery and an auxiliary battery (i.e., battery for auxiliary devices) arranged in the rear of the vehicle. In this power supply device, a fusible link box is arranged near the auxiliary battery of 12 V, and a power line that is an output line of a DC/DC converter performing voltage conversion between the high-voltage battery and the auxiliary battery is not returned to an engine room but is connected to the fusible link box. According to the disclosure, wiring paths of electric power lines can be easily ensured in this power supply device for the vehicle.

Japanese Patent Laying-Open No, 2005-178732 has disclosed a cooling device of a high-voltage electric device for a vehicle motor. In this device, a battery, an inverter, a DC-DC converter and a fan are arranged concentratedly under a rear seat, a cooling air inlet is arranged under one side, in a vehicle width direction, of the rear seat and a cooling air outlet is arranged under the other side. According to the disclosure, this device can efficiently cool high-voltage electric units without causing lowering of utility and the like.

Japanese Patent Laying-Open No. 9-149552 has disclosed a power supply device that includes a main battery having a voltage of 300 V, a voltage converter converting the voltage of the main battery into 12 V and a voltage converter converting the voltage of the main battery into 24 V.

Japanese Patent Laying-Open No. 9-200902 has disclosed a power supply device for an electric vehicle that includes a main power supply feeding a electric power to a drive motor controlled by a drive motor control device, and a plurality of sub-power supplies that are employed for supplying powers to electric loads of various rated voltages different from that of the drive motor, and are formed of voltage converters for converting the voltage of the main power supply into voltages corresponding to the various rated voltages of the plurality of sub-power supplies, respectively.

The voltages taken out from the power supply device are, e.g., about 12 V and 30 V, respectively. In recent years, a power supply for a voltage(s) different from these voltages has been required in some cases. In some cases, the voltage of about 12 V cannot provide a sufficient drive power, e.g., to an electric power steering device that is driven by an electric motor, and the voltage of about 300 V is excessively high for it. Accordingly, it has been studied to use electricity, e.g., of about 40 V as the power supply for driving the electric power steering. As described above, another kind of voltage is required in addition to the voltages supplied from the conventional power supply in some cases.

The power supply package disclosed in the above Japanese Patent Laying-Open No. 2004-114821 includes the 36-V battery and 12-V battery. These batteries arranged for the high and low voltage systems, respectively, increase the sizes of the power supply device. In the Japanese Patent Laying-Open No. 9-149552 or 9-200902, the main battery is connected to a plurality of voltage converters for supplying the electricity of a plurality of voltages, but the structures and arrangement of the various devices or units are not disclosed.

DISCLOSURE OF THE INVENTION

An object of the invention is to provide a power supply device of small sizes that can supply electricity of three or more kinds of voltages as well as a vehicle provided with the power supply device.

A power supply device according to the invention is a power supply device to be mounted on a vehicle, and includes a power storage unit; a power storage casing for accommodating the power storage unit; a first converter stepping down an output voltage of the power storage unit to a first voltage; and a second converter stepping down the output voltage of the power storage unit to a second voltage. The power storage unit as well as the first and second converters are fixed to the power storage casing.

Preferably, in the invention, the first converter is arranged at one end of the power storage casing. The second converter is arranged at the other end opposite to the one end of the power storage casing.

Preferably, in the invention, the first converter is configured to be forcedly cooled by a cooling device. The second converter is configured to be cooled by self-cooling.

A vehicle according to the invention is provided with the foregoing power supply device, and the first and second converters are arranged at widthwise opposite ends of a vehicle body, respectively. The first and second converters are arranged without protruding from front and rear end surfaces, on front and rear sides of the vehicle body, of said power storage casing.

The invention can provide the power supply device of small sizes that can supply three or more kinds of voltages as well as a vehicle provided with the power supply device.

BEST MODES FOR CARRYING OUT THE INVENTION

Referring toFIGS. 1 to 6, a power supply device and a vehicle provided with the power supply device according to an embodiment of the invention will be described below.

FIG. 1is a schematic perspective view of the power supply device according to the embodiment. The power supply device according to the embodiment is mounted on the vehicle. An arrow61indicates a forward direction of a vehicle body.

A power storage unit such as a secondary battery or a capacitor is mounted on the vehicle together with a power storage casing accommodating it. In this invention, a unit including the power storage unit and the power storage casing is referred to as a power storage pack. The power storage pack may include other components. The other components include, e.g., an air blower such as a cooling duct and/or a cooling fan for cooling the power storage unit.

The power supply device according to the embodiment includes a power storage pack1, which includes a battery module31as a power storage unit. The battery module in the embodiment is a secondary battery. Battery module31is configured to supply an electric power to a motor during start, acceleration or hill climbing, and to store an electric power regeneratively generated during deceleration.

Battery module31in the embodiment includes a plurality of battery cells. Battery module31is formed of an arrangement of the plurality of battery cells. In battery module31in the embodiment, the battery cells of 1.2 V are connected together in series to output a voltage of 288 V.

Power storage pack1in the embodiment includes a power storage casing21for accommodating the power storage unit. Power storage casing21has a box-like form, and includes a lower casing22and upper casings23and24. Lower casing22has plates25. Plates25can be fixed to a carrier member of the vehicle body. Plates25are formed at a rear end (i.e., an end on the rear side of the vehicle) of power storage casing21.

Power storage pack1in the embodiment includes an electric unit34. Power storage pack1includes a DC/DC converter2that is electrically connected to battery module31and serves as a first converter for stepping down the voltage to a first voltage. DC/DC converter2in the embodiment is configured to convert the output of 288 V of battery module31into 12 V. DC/DC converter2is arranged inside power storage casing21.

Power storage pack1includes a DC/DC converter3that serves as a second converter for stepping down the voltage of battery module31to a second voltage. DC/DC converter3in the embodiment is configured to convert the output of 288 V of battery module31into 42 V.

In the embodiment, DC/DC converter3is arranged outside power storage casing21. DC/DC converter3is fixed to an outer surface of upper casing23. DC/DC converter3is connected to battery module31via a lead wire (not shown).

Upper casing24in the embodiment has an intake duct24afor leading a cooling air into power storage casing21. Upper casing24has an exhaust duct24bfor discharging the cooling air from the inside of power storage casing21.

FIG. 2is a schematic cross section of the vehicle provided with the power supply device according to the embodiment. The vehicle according to the embodiment is a so-called sedan type of automobile. The vehicle includes a body41, which has a longitudinal direction. The vehicle of the embodiment includes tires42and47. Tires42are front tires, and tires47are rear tires.

The vehicle according to the embodiment has two rows of seats, i.e., front seats43aand43bas well as a rear seat44. Rear seat44is the most rearmost seat. The vehicle has a steering wheel45arranged in front of front seat43a, i.e., a driver's seat.

Power storage pack1in the embodiment is arranged behind rear seat44. Power storage pack1is arranged such that a longitudinal direction thereof is substantially parallel to the width direction of the vehicle. Power storage pack1is arranged inside a trunk room.

FIG. 3is a schematic exploded perspective view of the power storage pack in the embodiment. In the embodiment, various units are arranged in lower casing22. Upper casings23and24are configured to cover the various units arranged in lower casing22. Upper casings23and24are fitted to lower casing22as indicated by arrows62and63.

Lower casing22has a base plate22afor arranging electric unit34, DC/DC converter2and the like thereon. Base plate22ahas a through hole (not shown) to pass the cooling air therethrough.

Electric unit34includes a relay for controlling a voltage circuit receiving electricity from battery module31, various sensors or a battery computer for sensing states of battery module31and the like. Electric unit34is arranged near a side of battery module31.

Power storage pack1in the embodiment has a service plug32. Service plug32is configured such that a high-voltage circuit can be interrupted by pulling out service plug32from the body of power storage pack1for inspecting or maintaining power storage pack1. Upper casing24has an opening24dfor exposing service plug32.

DC/DC converter2can step down the high voltage provided from battery module31to a voltage for use in auxiliary devices such as lamps of the vehicle and an audio device as well as various ECUs (Electronic Control Units) mounted on the vehicle.

DC/DC converter2in the embodiment can charge the auxiliary battery (not shown). DC/DC converter2has a rectangular parallelepiped form. DC/DC converter2is fixed to base plate22aof lower casing22. A longitudinal direction of DC/DC converter2is substantially parallel to the width direction of power storage pack1.

DC/DC converter2has fins2a. Each fin2ahas a plate-like form. DC/DC converter2is arranged with fins2adirected outward. DC/DC converter2in the embodiment is arranged with fins2aextending in a sideway direction of the vehicle body. Fins2aare arranged at an end of power storage casing21.

DC/DC converter2has a connection unit2bfor supplying the stepped-down electricity. Connection unit2bin the embodiment is directed toward the rear side of the vehicle body from DC/DC converter2. Upper casing24has an opening24cfor exposing connection unit2b. A lead wire is connected to connection unit2bfor supplying the electricity of 12 V.

Power storage pack1in the embodiment has an output terminal33for externally supplying the electricity of 288 V of battery module31. Output terminal33is connected, e.g., to an inverter for supplying AC electricity to the motor. Output terminal33is arranged near the side of battery module31. Output terminal33in the embodiment is directed to the front side of the vehicle body.

Power storage pack1in the embodiment has a communication cable35for external communications. Communication cable35allows communications with external control units. Upper casing24has an opening24efor passing communication cable35therethrough.

DC/DC converter3has a rectangular parallelepiped form. A longitudinal direction of DC/DC converter3is substantially parallel to the width direction of the power storage pack. A length of DC/DC converter3in the longitudinal direction is shorter than a length of upper casing23in its width direction. DC/DC converter3thus arranged does not protrude from the end surfaces, on the front and rear sides of the vehicle body, of upper casing23.

DC/DC converter3has a connection unit3bfor supplying the stepped-down electricity. By connecting a lead wire to connection unit3b, the stepped-down electricity of 42 V is supplied. DC/DC converter3in the embodiment has fins3afor cooling the DC/DC converter. Each fin3ahas a plate-like form.

The power of 42 V supplied from DC/DC converter3is used, e.g., for the electric power steering. The electric power steering has a function of adding an axial force for the steering wheel by an electric motor or the like. For example, an axis-rotating force of a steering wheel may be large in a large vehicle. Even in a small vehicle, an axis-rotating force of a steering wheel may increase depending on grounding conditions of tires. In these vehicles, the power supply of 12 V cannot provide a sufficient axis-rotating force. The power supply device according to the embodiment can supply the electricity of the voltage of 42 V, and can stably assist the steering even in the vehicle requiring a large axis-rotating force for the steering wheel.

Upper casing24has a partition24gfor arranging battery module31in a closed space. Partition24gis spaced from battery module31with intake duct24atherebetween.

FIG. 4is a first schematic cross section showing the battery pack arranged in the vehicle according to the embodiment.FIG. 5is a second schematic cross section showing the battery pack arranged in the vehicle according to the embodiment.FIG. 4is the schematic cross section taken along a vertical plane.FIG. 5is the schematic cross section taken along a horizontal plane.

Referring toFIGS. 4 and 5, the vehicle according to the embodiment includes side members52, which are arranged on the widthwise opposite ends of the vehicle, respectively. Each side member52extends in the longitudinal direction of the vehicle. The vehicle of the embodiment has a cross member53. Cross member53extends in the width direction of the vehicle. Cross member53is fixed to side members52to couple them together.

The vehicle according to the embodiment includes a floor panel48, which has a plate-like form. Floor panel48in the embodiment is fixed to the lower surfaces of side members52. Floor panel48has a portion carried by cross member53. Floor panel48carries rear seat44.

A partition panel49is arranged behind rear seat44. Partition panel49is arranged to partition a space into a cabin for persons and a trunk room for baggage. Partition panel49has a lower end fixed to floor panel48and an upper end fixed to an upper back50. Opposite ends in the vehicle width direction of partition panel49are fixed to strainers (not shown), respectively.

Power storage pack1in the embodiment is arranged behind partition panel49. Power storage pack1is arranged in the trunk room. Power storage pack1is fixed to floor panel48. Power storage pack1is arranged in a region between side members52that are arranged on the opposite sides spaced in the vehicle width direction from each other, respectively.

An end of power storage pack1opposed to the cabin is fixed to floor panel48via a bracket28. An end of power storage pack1remote from the cabin is fixed to floor panel48via a bracket27. In power storage pack1, plates25are fixed to bracket27. In power storage pack1, plates26are fixed to bracket28.

The power supply device in the embodiment includes first and second converters. The power storage unit and the first and second converters are fixed to the power storage casing. This structure can provide the power supply device that can supply at least three kinds of voltages. The power supply device in the embodiment can supply the electricity of DC voltages of 288 V, 42 V and 12 V. Further, the respective converters and the power storage unit are integrated to form the pack so that the power supply device can be small in size.

DC/DC converter2according to the embodiment is arranged at the longitudinal end of power storage pack1remote from the side on which battery module31is arranged. DC/DC converter2is arranged at one end of power storage pack1. When power storage pack1is mounted on the vehicle body, DC/DC converter2is located near the right end of the vehicle body.

DC/DC converter3in the embodiment is arranged at the longitudinal end of power storage pack1on the same side as battery module31. DC/DC converter3is arranged at the end remote from the foregoing one end. When power storage pack1is mounted on the vehicle body, DC/DC converter3is located near the left end of the vehicle body.

In the embodiment, as described above, DC/DC converters2and3are arranged on the widthwise opposite ends of the vehicle body, respectively. This structure can space the DC/DC converters from each other. Also, this structure can space the parts outputting the different voltages, respectively, from each other. Consequently, it is possible to suppress short circuit between the power supply systems of different voltages as well as generation of noises. For example, if the DC/DC converter were located at the end, on the forward side of the vehicle body, of the power storage pack, the DC/DC converter might be caught between the power storage pack body and the rear seat when a collision from the rear side occurred. By arranging the DC/DC converter on the widthwise opposite ends of the vehicle body, it is possible to avoid the catching of the DC/DC converter between the power storage pack body and the rear seat even when the collision from the rear side occurs.

In the embodiment, DC/DC converters2and3are configured not to protrude from the front and rear end surfaces of the vehicle body, respectively. In a plan view of power storage pack1, DC/DC converters2and3are arranged within a region of power storage casing21. This structure can suppress damages of the DC/DC converter when the power supply device receives an impact in any one of the directions.

For example, when the power supply device receives an impact in a sideway direction of the vehicle body, the impact is directly applied to power storage casing21so that it is possible to suppress the direct application of the impact to DC/DC converters2and3. Consequently, the damages of DC/DC converters2and3can be suppressed.

The power storage pack of the embodiment is arranged in the region between the side members that are arranged on the sides spaced from each other in the width direction of the vehicle body, respectively. The side members are parts forming a framework of the vehicle body, and have a high strength. Therefore, even when the impact is applied sideways, the side members can protect the power storage pack.

FIG. 6is a schematic cross section of the power supply device according to the embodiment.FIG. 6is the schematic cross section taken along line VI-VI inFIG. 1. Partition24gof upper casing24partitions the interior into a region where electric unit34is arranged and a region where battery module31is arranged.

Battery module31is placed on base plate22a. An air blower (not shown) supplies a cooling air as indicated by an arrow64into the power supply device according to the embodiment. The air blower is configured, e.g., to supply the air taken from the trunk room.

The cooling air is supplied through intake duct24a. The cooling air flows through spaces between the battery cells of battery module31as indicated by arrows65, and thereby cools each battery cell.

The cooling air passes through a space between the bottom plate of lower casing22and base plate22aas indicated by an arrow66. The cooling air is discharged from exhaust duct24bas indicated by an arrow67. Exhaust duct24bis connected to a duct (not shown) through which the cooling air is discharged from the vehicle.

When the cooling air is discharged from power storage pack1, the cooling air passes through a region where fins2aof DC/DC converter2are arranged. The cooling air cools fins2a, and thereby cools DC/DC converter2itself.

This embodiment is configured to cool forcedly DC/DC converter2, i.e., the first converter by the cooling device. In the embodiment, the air passage is artificially formed, and at least a part of DC/DC converter2is located in this air passage so that DC/DC converter2is cooled. Conversely, DC/DC converter3is arranged above upper casing23, and is cooled by self-cooling without performing forced cooling.

The vehicle carries many units that use, as power supplies, the electricity of 12 V supplied from DC/DC converter2of the embodiment. DC/DC converter2is used frequently, and therefore generates a large amount of heat. However, DC/DC converter2is forcedly cooled so that it can perform stable driving.

Conversely, only a small number of units uses, as power supplies, the electricity of 42 V supplied from DC/DC converter3in the embodiment. DC/DC converter3is used less frequently than DC/DC converter2, and generates a smaller amount of heat. Therefore, DC/DC converter3can be sufficiently cooled by the self-cooling and thereby can perform stable driving.

By cooling the DC/DC converter generating a small amount of heat by the self-cooling, the electric power required for the forced cooling can be small, and also the structure of the power supply device can be simple.

In the embodiment, DC/DC converter2is arranged inside power storage casing21, and DC/DC converter3is arranged outside power storage casing21. This is not restrictive, and each DC/DC converter may be arranged on either side of the power storage casing.

In the embodiment, the converters are arranged at the longitudinally opposite ends of the power storage casing. However, another form may be employed, and each converter can be arranged in arbitrary position. In the embodiment, two DC/DC converters are employed for one power supply device. However, another form may be employed, and three of more DC/DC converters may be arranged. The foregoing structures of the power supply device in the embodiment may be appropriately combined or only a part of these structures may be used to form a new power supply device.

In the foregoing drawings, the same or corresponding portions bear the same reference numbers.

Industrial Applicability

The invention is primarily applied to a vehicle provided with a power storage unit such as a secondary battery or a capacitor.