Electricity storage module

An electricity storage module includes: an electric storage unit block that is constituted by arraying a plurality of prismatic electric storage units through a holding member; and a cooling channel that is formed between the electric storage unit and the holding member, through which a cooling medium for cooling the electric storage unit flows. A part of a cooling medium inlet opening of the cooling channel is covered so that a flow speed of a cooling medium after flowing into the cooling channel is higher than a flow speed of a cooling medium before flowing into the cooling channel.

TECHNICAL FIELD

The present invention relates to an electricity storage module that is capable of storing and releasing electrical energy.

BACKGROUND ART

Performance of a electricity supply unit that includes an electricity storage module that is capable of storing and releasing electrical energy is dependent on how much heat generated by the work of a plurality of electric storage units that constitute the electricity storage module is controlled, in other words, how efficiently a plurality of electric storage units can be cooled. Normally, a plurality of electric storage units are cooled by supplying in a parallel direction or a perpendicular direction a cooling medium to the plurality of electrically connected electric storage units and, in order to efficiently cool the plurality of electric storage units, it is necessary to efficiently distribute a cooling medium to a plurality of electric storage units at a uniform flow rate. In addition, it is necessary to improve cooling performance of the electric storage units that lie downstream of the cooling medium. For this reason, it has conventionally been devised to cause turbulence in a cooling medium that flows on the surface of electric storage units and, using this turbulence effect, to improve heat transfer performance between the cooling medium and the electric storage unit surfaces or to increase a heat transfer area from the electric storage units to the cooling medium. The conventional cooling techniques described above are disclosed in Patent Literatures 1 and 2.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In order to achieve electric storage units with high performance, temperature reduction in the electric storage units by cooling and uniformization of temperature distribution (removal of temperature gradient) are very important. However, the conventional cooling techniques consider temperature reduction in the electric storage units but do not consider uniformization of temperature distribution of the electric storage units. In addition, the conventional cooling techniques do not consider cooling of an electrode terminal of the electric storage units.

Solution to Problem

An electricity storage module according to a first aspect of the present invention, comprises: an electric storage unit block that is constituted by arraying a plurality of prismatic electric storage units through a holding member; and a cooling channel that is formed between the electric storage unit and the holding member, through which a cooling medium for cooling the electric storage unit flows, wherein: a part of a cooling medium inlet opening of the cooling channel is covered so that a flow speed of a cooling medium after flowing into the cooling channel is higher than a flow speed of a cooling medium before flowing into the cooling channel.

According to a second aspect of the present invention, in the electricity storage module according to the first aspect, a covering member may be provided in the cooling medium inlet opening of the cooling channel so as to cover the part of the cooling medium inlet opening.

According to a third aspect of the present invention, in the electricity storage module according to the first or second aspect, a guiding member that deflects a flow of the cooling medium to a direction to a center of the electric storage unit may be provided on a most upstream side of the cooling channel.

According to a fourth aspect of the present invention, in the electricity storage module according to the third aspect, a guiding member that deflects a flow of the cooling medium to a direction outwards from the center of the electric storage unit may be provided on a most downstream side of the cooling channel.

According to a fifth aspect of the present invention, in the electricity storage module according to the fourth aspect, the cooling channel may be divided by connecting the guiding member that is provided on the most upstream side of the cooling channel with the guiding member that is provided on the most downstream side of the cooling channel.

According to a sixth aspect of the present invention, in the electricity storage module according to the first aspect, a conductive member for electrically connecting the electric storage units may be provided in the cooling medium inlet opening of the cooling channel so as to cover the part of the cooling medium inlet opening.

According to a seventh aspect of the present invention, in the electricity storage module according to the sixth aspect, it is preferable that a baffle plate is provided on a most upstream side or a most downstream side of the cooling channel.

According to an eighth aspect of the present invention, in the electricity storage module according to the sixth aspect, a baffle plate may be provided on a most upstream side and a most downstream side of the cooling channel.

According to a ninth aspect of the present invention, in the electricity storage module according to any of the sixth to eighth aspects, it is preferable that a guiding member that deflects a flow of the cooling fluid to a direction to a center of the electric storage unit is provided on a most upstream side of the cooling channel; and a guiding member that deflects a flow of the cooling fluid to a direction outwards from the center of the electric storage unit is provided on a most downstream side of the cooling channel.

Advantageous Effect of the Invention

According to a representative one of the present invention, since the flow speed of a cooling medium after having flown into a cooling channel formed between prismatic electric storage units becomes higher than the flow speed of a cooling medium before having flown into the cooling channel, the heat transfer performance of the cooling medium and the electric storage units can be improved. Due to this, according to the representative one of the present invention, temperature rise can be effectively reduced in a region with the highest temperature of the electric storage units, in particular, the center of the electric storage units, and uniformization of temperature distribution of the electric storage units can be facilitated. Thus, according to the representative one of the present invention, input/output characteristics of energy in individual electric storage units can be improved and the life of the electric storage units can be extended, variation in input/output characteristics of energy and the life between the plurality of electric storage units can be reduced and furthermore, the electricity storage module can be downsized and its reliability can be improved.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present invention will now be explained.

The embodiments will be explained below with an example in which the present invention is applied to an electrical storage device that constitutes an in-vehicle power supply unit of an electric-powered vehicle, in particular, an electric vehicle.

While as an electric vehicle, a hybrid electric vehicle that includes an engine that is an internal combustion engine and an electric machine as driving sources of the vehicle will be explained as an example, the present invention may be applied to another electric vehicle such as a pure electric vehicle, which has an electric machine as the only driving source of the vehicle and can be charged from mains electricity and at the charging station, and a plug-in hybrid electric vehicle, which has an engine and an electric machine as driving sources of the vehicle and can be charged from mains electricity and at the charging station.

While as an electrical storage device that constitutes an in-vehicle power supply unit, a lithium-ion battery device that includes a prismatic lithium-ion secondary battery cell (hereinafter referred to as a “prismatic battery cell”) as an electric storage unit will be explained as an example, the present invention may be applied to a device that includes another prismatic electric storage unit capable of storing and releasing electrical energy that includes, for example, a nickel-metal hydride battery, a lead-acid battery, a condenser, a capacitor, and the like.

The structure of the embodiments explained below can be applied to an electrical storage device that constitutes a vehicle power supply unit for another electric-powered vehicle such as a railway vehicle such as a hybrid train, a share-ride vehicle such as a bus, a freight vehicle such as a truck, and an industrial vehicle such as a battery-powered forklift truck.

In addition, the structure of the embodiments explained below can also be applied to an electrical storage device that constitutes a power supply unit other than an electric-powered vehicle, such as an uninterruptible power supply unit that is used for a computer system, a server system, and the like, a power supply unit that is used for home electricity generation equipment, and a power supply unit that is used for electricity generation equipment using natural energy such as sunlight, wind power, and geothermal heat.

The embodiments of the present invention will now be specifically explained with reference to the drawings.

First Embodiment

The first embodiment of the present invention will be explained based uponFIG. 1toFIG. 5.

A lithium-ion battery device of the present embodiment (hereinafter simply referred to as a “battery device”) is constituted by housing in a battery case a prismatic battery module, a control device that manages and controls a state of the prismatic battery module, a cooling fan that circulates a cooling medium that cools the prismatic battery module (for instance, cooling air), and the like. The prismatic battery module includes a prismatic battery assembly (or a prismatic battery block)10. The prismatic battery assembly10is configured by alternately arranging vertically-placed prismatic battery cells1and cell holders2in a row and electrically connecting the plurality of prismatic battery cells in series. WhileFIG. 1andFIG. 2show four of the prismatic battery cells1, the prismatic battery assembly10is constituted with more prismatic battery cells1, for example, eight or twelve prismatic battery cells1practically.

The prismatic battery cell1includes a cell can1A, an electricity generating component group1B housed inside the cell can1A, and a pair of positive and negative electrode terminals4.

The cell can1A, which is a flat hexahedron or short prism metal can whose height dimension is less than each of its length and width dimensions, includes a top surface and a bottom surface whose areas are each the largest and four side surfaces whose areas are each less than each of the top surface and the bottom surface. The top surface, the bottom surface, and the side surfaces each have a rectangular (oblong) shape.

It is to be noted that the vertical placement of the prismatic battery cell1refers to a placement of the prismatic battery cell1so that the top surface and the bottom surface of the cell can1A are perpendicular to the mounting surface of the prismatic battery cell1. In addition, a placement of the prismatic battery cell1so that the top surface and the bottom surface of the cell can1A are parallel to the mounting surface of the prismatic battery cell1is referred to as a horizontal placement.

The electricity generating component group1B housed inside the cell can1A is a winding body in which a positive plate1cand a negative plate1bare wound through a separator1aand, as shown inFIG. 5, is a winding assembly in which the belt-like laminated body where the separator1a, the negative plate (negative sheet)1b, the separator1a, and the positive plate (positive sheet)1care laminated in this order is wound so that a cross section of the winding becomes elliptical or oval. In addition, there is electrolyte solution inside the cell can1A.

The positive plate1cis a thin foil current collector of, for example, 20 μm thick, more specifically, an aluminium foil with positive-electrode active material mix such as lithium manganate coated on both sides thereof as a positive-electrode active material. The negative plate1bis a thin foil current collector of, for instance, 20 μm thick, more specifically, a copper foil with negative-electrode active material mix such as graphite coated on both sides thereof as a negative-electrode active material. The separator1ais a thin member of, for example, 30 μm thick, more specifically, a resin microporous insulating film such as polyethylene and polypropylene.

The pair of positive and negative electrode terminals4are cylindrical or bolt-like conductive members that protrude from both longitudinal end portions of one of the side surfaces of the cell can1A, i.e., the side surface that is opposite to the side surface that serves as the mounting surface of the prismatic battery cell1. The positive electrode-side electrode terminal4is electrically connected to a positive electrode of the electricity generating component group1B. The negative electrode-side electrode terminal4is electrically connected to a negative electrode of the electricity generating component group1B.

It is to be noted that the electrode terminal4may be a terminal that has a flat, plate-like end portion.

The plurality of prismatic battery cells1are electrically connected in series by electrically connecting the positive electrode-side electrode terminal4of one of the adjacent prismatic battery cells1with the negative electrode-side electrode terminal4of the other of the adjacent prismatic battery cells1. Here, the adjacent prismatic battery cells1are arranged in a state where one of the adjacent prismatic battery cells1rotates 180 degrees with respect to the other of the adjacent prismatic battery cells1about the central axis that extends in the mounting direction of the prismatic battery cells1in a direction parallel to the top surface and the bottom surface when the prismatic battery cells1are placed vertically) as a rotational axis. By doing this, the positive electrode-side electrode terminal4of the one of the adjacent prismatic battery cells1and the negative electrode-side electrode terminal4of the other of the adjacent prismatic battery cells1, which is electrically connected thereto, are arrayed in the same position, thereby allowing the both to be connected with ease via a bus bar that is a conductive connection member.

The cell holder2is an irregularity member that electrically insulates between the adjacent prismatic battery cells1as well as forming a certain interval between the adjacent prismatic battery cells1and transferring to the prismatic battery cells1pressure (constraint force or holding force) that is applied from an array direction of the prismatic battery cells1(from a direction perpendicular to the to surface and the bottom surface when the prismatic battery cells1are vertically placed) to the prismatic battery assembly10so as to retain the prismatic battery cells1. The cell holder2is a plastic molding that is formed from an electrically insulating member.

The cell holder2includes a planar portion2aand a protrusion (ridge)2b. The planar portion2a, which is a plate member that faces opposite to the top surface or the bottom surface of the prismatic battery cell1, includes a plane that has the same size and the same shape as those of the top surface or the bottom surface of the prismatic battery cell1. The protrusion2bis a part that extends in a straight line from one longitudinal end of the planar portion2ato the other thereof and is formed so as to perpendicularly protrude from three locations on the front and back surfaces of the planar portion2a, i.e., both transverse end portions (edge portions) and the center portion of the planar portion2atowards the prismatic battery cell1. The protrusion heights of the three protrusions2bare the same. The protrusion2bof the center portion also serves as a restraint section that presses the center portion of the prismatic battery cell1from the opposite direction and restrains bulge that occurs at the center portion of the prismatic battery cell1.

It is to be noted that the cell holder2may have a structure in which the prismatic battery cell1is surrounded and held. In this case, a protrusion that protrudes toward the prismatic battery cell1more than the protrusion2bdoes may be provided outside the protrusion2bprovided at the both transverse end portions of the planar portion2aof the cell holder2.

Between the cell holder2and the prismatic battery cell1, a cooling channel9through which a cooling medium3that cools the prismatic battery cell1, e.g., cooling air, flows is formed. In the prismatic battery cell1, the top and bottom surfaces of the cell can1A are cooled by the cooling medium3that flows through the cooling channel9formed on the both sides of the array direction of the prismatic battery cells1. The cooling channel9is formed with the planar portion2aand the protrusions2bof the cell holder2and the top surface or the bottom surface of the prismatic battery cell1so that the cooling channel9extends from one end portion side of the prismatic battery cell1in the longitudinal direction to the other end portion side in a straight line in order to cause the cooling medium3to flow from the one end portion side of the prismatic battery cell1towards the other end portion side in the longitudinal direction while cooling a surface of the cell can1A and to be divided into two in the transverse direction of the prismatic battery cell1. The divided two cooling channels9have the same width in the transverse direction.

A cooling medium inlet opening9a(the most upstream of the cooling channel9) formed at the one end portion in the longitudinal direction of the prismatic battery cell1is provided with a baffle plate5. The baffle plate5is a rectangular (oblong) flat plate member that is integrally formed on the cell holder2so as to be perpendicular to the protrusion2bat the front end of the one longitudinal side (the one end portion side in the longitudinal direction of the prismatic battery cell1) of the protrusion2bprovided at the transverse center portion of the cell holder2. The baffle plate5covers a part of the cooling medium inlet opening9aat the transverse center portion of the cell holder2(the boundary portion of the two cooling channels9formed by being divided in the transverse direction of the prismatic battery cell1). In addition, the baffle plate5is provided to protrude perpendicularly from the front and back surfaces of the planar portion2aof the cell holder2towards the prismatic battery cell1. The protrusion height of the baffle plate5is the same as the protrusion height of the protrusion2b.9brepresents a cooling medium outlet opening

It is to be noted that the baffle plate5may be integrated with or separated from the protrusion2b.

In this manner, a member that covers a part of the cooling channel9, for example, the baffle plate5is provided on an upstream side of the cooling channel9, preferably the most upstream thereof. The baffle plate5can be provided with ease by being formed integrally with the cell holder2provided between the prismatic battery cells1. When the baffle plate5covers a part of the cooling medium inlet opening9a, an inflow area of the cooling medium3at the cooling medium inlet opening9abecomes less than an outflow area of the cooling medium outlet opening9b(the most downstream of the cooling channel9) formed at the other end portion in the longitudinal direction of the prismatic battery cell1or a flow area inside the cooling channel9. Accordingly, if the cooling medium3is caused to flow in at the same flow rate as that without the baffle plate5, the flow speed of the cooling medium3inside the cooling channel9becomes higher than the flow speed of the cooling medium3before flowing into the cooling channel9through the cooling medium inlet opening9a.

As the flow speed of the cooling medium3becomes higher, the heat transfer rate between the top surface or the bottom surface of the prismatic battery cell1and the cooling medium3becomes greater in a region more downstream than the cooling medium inlet opening9a, so that temperature rise due to charge/discharge of the prismatic battery cell1can be reduced in a region more downstream than the cooling medium inlet opening9a, the region where temperature becomes high, in particular, the center portion of the prismatic battery cell1. This allows temperature in the center portion of the prismatic battery cell1, i.e., the region where temperature becomes highest to be brought close to temperature in another region, and hence temperature distribution at the prismatic battery cell1can be brought close to uniformity.

Hence, according to the cooling structure of the battery module of the present embodiment, cooling performance of the prismatic battery cell1can be improved more than ever. Due to this, according to the prismatic battery cell1of the present embodiment, high performance, for instance, improvement in charge/discharge characteristics (or input/output characteristics), extension of the life, and the like can be achieved. In addition, according to the battery module of the present embodiment, improved cooling performance reduces variation in charge/discharge characteristics between the plurality of prismatic battery cells1and variation in their lives. In addition, according to the battery module of the present embodiment, improved cooling performance allows improvement in downsizing and reliability to be achieved.

It is to be noted that although in a region immediately after the baffle plate5, there is a part in which the flow speed of the cooling medium3becomes low and cooling efficiency is slightly reduced, an appropriate selection of the size of the baffle plate5can limit reduction in cooling efficiency due to reduction in the flow speed of the cooling medium3.

In addition, another shape, for example, a half circle shape may be adopted in the baffle plate5as long as the operations and advantageous effects mentioned above can be achieved.

In addition, the cooling medium3is guided to the cooling medium inlet opening9aby a blower (cooling fan) and a ventilation duct not shown in the figures and is released from the cooling medium outlet opening9b.

Second Embodiment

The second embodiment of the present invention will be explained based uponFIG. 6toFIG. 8.

The present embodiment, which is an improvement example of the first embodiment, has a part of the structure of the cell holder2that is different from that of the first embodiment. The other parts of the structure are the same as those of the first embodiment. For this reason, parts that are the same as those of the first embodiment are designated by the same reference numerals of the first embodiment, and their description will be curtailed.

In the present embodiment, a baffle plate6with the same shape and the same size as the baffle plate5provided in the cooling medium inlet opening9ais provided, symmetrically to the baffle plate5, in the cooling medium outlet opening9b, which is the most downstream of the cooling channel9. This causes the cooling medium outlet opening9bto be partially covered in the transverse center portion of the cell holder2(the boundary portion of the two cooling channels9formed by being divided in the transverse direction of the prismatic battery cell1).

The baffle plate6is a flat plate member in a rectangular (oblong) shape integrally formed with the cell holder2so as to be perpendicular to the protrusion2bat the front end of the other longitudinal side (the other end portion side in the longitudinal direction of the prismatic battery cell1) of the protrusion2bprovided in the transverse center portion of the cell holder2. In addition, the baffle plate6is in a position relationship symmetrical to the baffle plate5. In addition, the baffle plate6is provided so as to perpendicularly protrude from the front and back surfaces of the planar portion2aof the cell holder2towards the prismatic battery cell1(it is to be noted that whileFIG. 8illustrates a case in which the protrusion2bis provided only on one surface, it is provided on the both surfaces in practice as explained.). The protrusion height of the baffle plate6is the same as the protrusion height of the protrusion2b.

It is to be noted that the baffle plate6may be integrated with or separated from the protrusion2b.

In the present embodiment, since the same operations and advantageous effects as those in the first embodiment can be achieved and the baffle plate6is provided symmetrically to the baffle plate5, holding force applied from the cell holder2to the prismatic battery cell1can act uniformly.

Third Embodiment

The third embodiment of the present invention will be explained based uponFIG. 9.

The present embodiment, which is an improvement example of the second embodiment, has a part of the structure of the cell holder2that is different from that of the second embodiment. The other parts of the structure are the same as those of the second embodiment. For this reason, parts that are the same as those of the second embodiment are designated by the same reference numerals of the second embodiment, and their description will be curtailed.

In the present embodiment, a pair of guide plates7are provided in the vicinity of the baffle plate5provided in the cooling medium inlet opening9a. The pair of guide plates7, which are each a flat plate member in a rectangular (oblong) shape that deflects a part of the flow of the cooling medium3to the center portion (the center portion of the prismatic battery cell1) of the cell holder2, are integrally formed with the cell holder2. In addition, the pair of guide plates7are arranged axisymmetrically about the protrusion2bprovided in the transverse center portion of the cell holder2as a central line. More specifically, the pair of guide plates7are members arranged in an A shape that slope inward from the transverse end portion sides of the cell holder2in a direction from the one side of the cell holder2in the longitudinal direction towards the other side thereof. In other words, the pair of guide plates7are members that are arranged so as to spread out in a direction from the other longitudinal side of the cell holder2to the one side thereof. In addition, the pair of guide plates7are provided so as to perpendicularly protrude from the front and back surfaces of the planar portion2aof the cell holder2towards the prismatic battery cell1. The protrusion heights of the pair of guide plates7are each the same as the protrusion height of the protrusion2b.

It is to be noted that another shape, for example, a circular arc shape in a quarter circle shape may be adopted in the guide plate7as long as the operations and advantageous effects mentioned above can be achieved.

In the present embodiment, the same operations and advantageous effects as those in the second embodiment can be achieved, and since the pair of guide plates7are provided, the flow of the cooling medium3can be deflected to the center portion of the prismatic battery cell1. Due to this, in the present embodiment, the center portion of the prismatic battery cell1where heat relatively remains can be effectively cooled, and cooling performance of the prismatic battery cell1can be further improved.

Fourth Embodiment

The fourth embodiment of the present invention will be explained based uponFIG. 10.

The present embodiment, which is an improvement example of the third embodiment, has a part of the structure of the cell holder2that is different from that of the third embodiment. The other parts of the structure are the same as those of the third embodiment. For this reason, parts that are the same as those of the third embodiment are designated by the same reference numerals of the third embodiment, and their description will be curtailed.

In the present embodiment, a pair of guide plates8that are arranged differently from the pair of guide plates7provided in the cooling medium inlet opening9aare provided, symmetrically to the pair of guide plates7, in the cooling medium outlet opening9b, which is the most downstream of the cooling channel9.

The pair of guide plates8are provided in the vicinity of the baffle plate6provided in the cooling medium outlet opening9b. The pair of guide plates8, which are each a flat plate member in a rectangular (oblong) shape that deflects a part of the flow of the cooling medium3in the center portion of the cell holder2(the center portion of the prismatic battery cell1) to the transverse end portion sides of the cell holder2, are integrally formed with the cell holder2. In addition, the pair of guide plates8are arranged axisymmetrically about the protrusion2bprovided in the transverse center portion of the cell holder2as a central line. More specifically, the pair of guide plates8are members arranged in an A shape that slope from inside the cell holder2towards the transverse end portion sides thereof in a direction from the one side of the cell holder2in the longitudinal direction towards the other side thereof. In other words, the pair of guide plates8are members that are arranged so as to spread out in a direction from the one longitudinal side of the cell holder2to the other side thereof. In addition, the pair of guide plates8are provided so as to perpendicularly protrude from the front and back surfaces of the planar portion2aof the cell holder2towards the prismatic battery cell1. The protrusion heights of the pair of guide plates8are each the same as the protrusion height of the protrusion2b.

It is to be noted that another shape, for example, a circular arc shape in a quarter circle shape may be adopted in the guide plate8of downstream as long as the operations and advantageous effects mentioned above can be achieved.

In the present embodiment, the same operations and advantageous effects as those in the third embodiment can be achieved, and since the pair of guide plates8are provided, the flow of the cooling medium3can be deflected outward from the center portion of the prismatic battery cell1. Thus, the flow of the cooling medium3can be regulated and the flow rate of the cooling medium3can be further increased. Due to this, in the present embodiment, the center portion of the prismatic battery cell1where heat relatively remains can be effectively cooled, and cooling performance of the prismatic battery cell1can be further improved.

Fifth Embodiment

The fifth embodiment of the present invention will be explained based uponFIG. 11.

The present embodiment, which is an improvement example of the fourth embodiment, has a part of the structure of the cell holder2that is different from that of the fourth embodiment. The other parts of the structure are the same as those of the fourth embodiment. For this reason, parts that are the same as those of the fourth embodiment are designated by the same reference numerals of the fourth embodiment, and their description will be curtailed.

In the present embodiment, the end portion, toward the guide plate8, of one (one transverse side of the cell holder2) of the pair of guide plates7and the end portion, toward the guide plate7, of one (one transverse side of the cell holder2) of the pair of guide plates8are connected through a protrusion (ridge)2cthat extends in the longitudinal direction of the cell holder2. In addition, the end portion, toward the guide plate8, of the other (the other transverse side of the cell holder2) of the pair of guide plates7and the end portion, toward the guide plate7, of the other (the other transverse side of the cell holder2) of the pair of guide plates8are connected through a protrusion (ridge)2cthat extends in the longitudinal direction of the cell holder2. Due to this, each of the cooling channels9that has been divided into two in the transverse direction of the cell holder2by the protrusion2bof the center portion in the transverse direction of the cell holder2is further divided into two in the transverse direction of the cell holder2. That is, in the present embodiment, the cooling channels9divided into four in the transverse direction of the cell holder2are formed. Each of the two cooling channels9(the cooling channels9formed between the protrusion2bof the center portion in the transverse direction of the cell holder2and the protrusions2c) arranged at the transverse center portion of the cell holder2has the same transverse width that is less than the transverse width of each of the two cooling channels9(the cooling channels9formed between the protrusions2bin the transverse end portions of the cell holder2and the protrusions2c) arranged at the both transverse end portions of the cell holder2. Each of the two cooling channels9arranged at the both transverse end portions of the cell holder2has the same transverse width. The protrusions2care integrally formed with the cell holder2so as to protrude from the planar portion2aof the cell holder2towards the top surface or the bottom surface of the prismatic battery cell1. The protrusion height of the protrusions2cis the same as the protrusion height of the protrusion2b. In addition, the protrusions2care integrally formed with the guide plate7and the guide plate8.

It is to be noted that the protrusions2cmay be formed in close proximity to the end portion of each of the guide plate7and the guide plate8separately from the guide plate7and the guide plate8or in contact with them.

In the present embodiment, the same operations and advantageous effects as those in the fourth embodiment can be achieved, and since the cooling channel9is divided by the protrusions2cinto the transverse end portion side and the center side of the cell holder2, the flow of the cooling air3that has been deflected by the guide plate7to the center portion of the cell holder2(the center portion of the prismatic battery cell1) can be assured to flow in the center portion of the cell holder2(the center portion of the prismatic battery cell1). Due to this, in the present embodiment, the center portion of the prismatic battery cell1where heat relatively remains can be cooled more effectively, and cooling performance of the prismatic battery cell1can be further improved.

In addition, in the present embodiment, since the two protrusions2care formed in addition to the three protrusions2b, pressure (constraint force or holding force) applied from the array direction of the prismatic battery cells1to the prismatic battery assembly10can be transmitted in a more dispersed manner from the cell holder2to each of the prismatic battery cells1, so that a holding strength of the prismatic battery cell1can be further improved. Due to this, in the present embodiment, vibration resistance and strength of the prismatic battery module can be improved. In addition, in the present embodiment, the center portion of the prismatic battery cell1is pressed from the opposite direction by the three protrusions, i.e., the protrusion2bof the center portion in the transverse direction of the cell holder2and the two protrusions2c, thereby further increasing force to restrain bulge that occurs in the center portion of the prismatic battery cell1. Due to this, in the present embodiment, bulge of the prismatic battery cell1can be further reduced and the performance of the prismatic battery cell1can be further improved.

Sixth Embodiment

The sixth embodiment of the present invention will be explained based uponFIG. 12andFIG. 13.

The present embodiment, which is an improvement example of the fifth embodiment, has a part of the structure of the cell holder2that is different from that of the fifth embodiment. The other parts of the structure are the same as those of the fifth embodiment. For this reason, parts that are the same as those of the fifth embodiment are designated by the same reference numerals of the fifth embodiment, and their description will be curtailed.

In the present embodiment, the cooling channel9formed between the protrusion2bprovided in the transverse end portion of the cell holder2and the protrusion2cis further divided into two in the transverse direction of the cell holder2. Due to this, in the present embodiment, a protrusion (ridge)2d, which has the same length, height, and shape as those of the protrusion2b, is provided between the protrusion2bprovided in the transverse end portion of the cell holder2and the protrusion2c. Due to this, in the present embodiment, the cooling channel9that is divided into six in the transverse direction of the cell holder2is formed. Each of the two cooling channels9that are formed between the protrusions2bin the both transverse end portions of the cell holder2and the protrusions2dhas the same transverse width that is less than the transverse width of the cooling channel9formed between the protrusion2dand the protrusion2cand is less than the transverse width of the cooling channel9formed between the protrusion2bof the center portion in the transverse direction of the cell holder2and the protrusion2c. Each of the two cooling channels9formed between the protrusion2dand the protrusion2chas the same transverse width that is greater than the transverse width of the cooling channel9formed between the protrusion2bof the center portion in the transverse direction of the cell holder2and the protrusion2c. The protrusions2dare integrally formed with the cell holder2so as to protrude from the planar portion2aof the cell holder2towards the top surface or the bottom surface of the prismatic battery cell1. The protrusion height of the protrusions2dis the same as the protrusion height of each of the protrusions2band2c.

In the present embodiment, since the two protrusions2dare formed in addition to the five protrusions2band2c, pressure (constraint force or holding force) applied from the array direction of the prismatic battery cells1to the prismatic battery assembly10can be transmitted in a further dispersed manner from the cell holder2to each of the prismatic battery cells1, so that a holding strength of the prismatic battery cell1can be further improved. Due to this, in the present embodiment, vibration resistance and strength of the prismatic battery module can be improved.

In addition, in the present embodiment, since the channel distribution and the flow speed of the cooling medium3can be appropriately set in accordance with the temperature distribution of the prismatic battery cell1by using the cooling channel9formed by the seven protrusions2b,2c, and2d, the baffle plates5and6, and the guide plates7and8, the temperature distribution of the prismatic battery cell1can be further uniformed. More specifically, cooling performance by the cooling medium3is controlled in accordance with the temperature distribution of the prismatic battery cell1as cooling performance of the cooling medium3flowing in the transverse center portion of the prismatic battery cell1is set to the maximum, cooling performance of the cooling medium3flowing in the both transverse end portions of the prismatic battery cell1is set to the minimum, and cooling performance of the cooling medium3in the intermediate portion between the transverse center portion of the prismatic battery cell1and the both transverse end portions of the prismatic battery cell1is set to the midway between the maximum and the minimum. This allows the temperature distribution of the prismatic battery cell1to be more uniformed than that of the first to the fifth embodiments. Hence, in the present embodiment, cooling performance of the prismatic battery cell1can be improved more than that of the first to the fifth embodiments.

Analysis Example

An example of analysis conducted using universal thermo-fluid analysis software will be explained based uponFIG. 14.

The analysis was conducted on the battery assemblies10according to the first to the sixth embodiments and a comparison example in which a battery assembly was configured using a cell holder2of the first embodiment from which the baffle plate5was removed.FIG. 14shows the maximum temperature rise (° C.) by heating at one prismatic battery cell of the first to the sixth embodiment and the comparison example.

As main analysis conditions, the cooling air temperature was set to 35° C., the heating value of the prismatic battery cell was set to approximately 6 W, the flow rate of the cooling air was set to 0.03 m3/minute (the surface flow speed of the prismatic battery cell was approximately 1.5 m/second), and the height of the protrusions that forms the cooling channel9was se to 2 mm.

As a result of the analysis, on the basis of the temperature 35° C. of the cooling air, while the maximum temperature on the surface of the prismatic battery cell was 49.1° C. in the comparison example, it was 48.9° C. in the first embodiment, 48.9° C. in the second embodiment, 46.3° C. in the third embodiment, 44.8° C. in the fourth embodiment, 45.6° C. in the fifth embodiment, and 42.6° C. in the sixth embodiment.

In each of the embodiments, a temperature reducing effect was achieved compared to the comparison example. Thus, the cooling structure according to the first to the sixth embodiments using the baffle plates5and6, the guide plates7and8, and the like is an effective means for improving cooling performance of a prismatic battery cell and, as well as improving the cooling efficiency of the prismatic battery cell, it can achieve uniformization of temperature distribution at the prismatic battery cell. Among the embodiments, the sixth embodiment has the highest effect and thus it is concluded to be the most effective means for improving cooling performance of a prismatic battery cell.

Seventh Embodiment

The seventh embodiment of the present invention will be explained based uponFIG. 15andFIG. 16.

The present embodiment, which is an example of achievement of the structure of the second embodiment by varying the first embodiment, has differences from the first embodiment in the position of the electrode terminals4of the prismatic battery cell1and the arrangement of the cell holder2. The other parts of the structure are the same as those of the first embodiment. For this reason, parts that are the same as those of the first embodiment are designated by the same reference numerals of the first embodiment, and their description will be curtailed.

In the present embodiment, one pole of the electrode terminals4(for example, the positive electrode terminal4) is provided in the longitudinal center portion of the side surface of one longitudinal end portion of the prismatic battery cell1and the other pole of the electrode terminal4(for instance, the electrode terminal4of negative electrode) is provided in the longitudinal center portion of the side surface of the other longitudinal end portion of the prismatic battery cell1. There is a difference in polarity between the electrode terminals4on the one longitudinal end side of the two prismatic battery cells1that are adjacent through the cell holder2and between the electrode terminals4on the other longitudinal end side. For this reason, the polarity of the electrode terminal4on one longitudinal end side of the prismatic battery cell1and the polarity of the electrode terminal4on the other end side in the array of the plurality of prismatic battery cells1(the prismatic battery assembly10) are alternated in accordance with the array order of the prismatic battery cells1.

In the two prismatic battery cells1that are adjacent through the cell holder2, the electrode terminals4are electrically connected via a bus bar11in the longitudinal center portion of either the side surface on one longitudinal end side or the side surface on the other end side. In addition, the electrode terminals4on the other side of either the side surface on the one longitudinal end side or the side surface on the other end side of the two prismatic battery cells1that are adjacent through the cell holder2are each electrically connected via the bus bar11with the electrode terminal4of opposite polarity of the prismatic battery cell1that is adjacent on the other side. Due to this, in the array of the plurality of prismatic battery cells1(the prismatic battery assembly10), a connection section of the electrode terminals4on one longitudinal end side of the two adjacent prismatic battery cells1and a connection section of the electrode terminals4on the other end side thereof are alternated in accordance with the array order of the prismatic battery cells1. In other words, in the array of the plurality of prismatic battery cells1(the prismatic battery assembly10), the connection section of the electrode terminals4on one longitudinal end side of the two adjacent prismatic battery cells1and the connection section of the electrode terminals4on the other end side thereof are alternately provided in a staggering manner in accordance with the array order of the prismatic battery cells1.

The bus bar11is a strip-like, copper or aluminium conductive member that, in the transverse center portion of the prismatic battery cell1, spans over and covers the cooling medium inlet opening9aor the cooling medium outlet opening9bof the cooling channel9across the adjacent prismatic battery cells1. In addition, the dimension of the bus bar11in the transverse direction of the prismatic battery cell1is substantially the same as that of the baffle plate5. Due to this, the bus bar11can serve similarly to the baffle plate5of the cell holder2and the bus bar11can be cooled by the cooling medium3. The bus bar11and the electrode terminal4may be connected by welding or by fixing with a screw member.

Then, in the present embodiment, the baffle plate5of the cell holder2is arranged between the adjacent prismatic battery cells1so as to be arranged on the opposite side of the side on which the bus bar11is arranged. More specifically, between the adjacent prismatic battery cells1on the near side shown inFIG. 15(the prismatic battery cell1on the nearest side is not shown in the figure), the center portion of the cooling medium inlet opening9aof the cooling channel9is covered by the baffle plate5and the center portion of the cooling medium outlet opening9bof the cooling channel9is covered by the bus bar11. Between the next adjacent prismatic battery cells1, the center portion of the cooling medium inlet opening9aof the cooling channel9is covered by the bus bar11(not shown in the figure) and the center portion of the cooling medium outlet opening9bof the cooling channel9is covered by the baffle plate5. Between the further next adjacent prismatic battery cells1, the center portion of the cooling medium inlet opening9aof the cooling channel9is covered by the baffle plate5(not shown in the figure) and the center portion of the cooling medium outlet opening9bof the cooling channel9is covered by the bus bar11. In this manner, as a means for covering the center portion of the cooling medium inlet opening9aand the cooling medium outlet opening9bof the cooling channel9, the baffle plate5of the cell holder2and the bus bar11are used alternately in accordance with the array order of the prismatic battery cells1.

In the present embodiment, a connection member that electrically connects the electrode terminals4between the adjacent prismatic battery cells1, i.e., the bus bar (conductive member)11functions also as a member that covers a part of the cooling channel9provided on an upstream side, preferable the most upstream, of the cooling channel9. Thus, in the present embodiment, since the same structure as that of the second embodiment can be achieved by varying the first embodiment, the same operations and advantageous effects as those of the second embodiment can be achieved. In addition, in the present embodiment, since the bus bar11can be cooled by the cooling medium3, heat at the prismatic battery cell1can be released from the electrode terminal4through the bus bar11and thus cooling performance of the prismatic battery cell1can be further improved.

Eighth Embodiment

The eighth embodiment of the present invention will be explained based uponFIG. 17.

The present embodiment is an improvement example of the seventh embodiment and an example in which the cell holder2of the second embodiment in which the baffle plates5and6are formed is applied to the cell holder2of the prismatic battery assembly10of the seventh embodiment. The other parts of the structure are the same as those of the seventh embodiment. For this reason, parts that are the same as those of the seventh embodiment are designated by the same reference numerals of the seventh embodiment, and their description will be curtailed.

As shown inFIG. 17, the bus bar11is provided so as to cover a part of the cooling medium inlet opening9aor the cooling medium outlet opening9bof the cell holder2in which the baffle plates5and6are formed. Due to this, in the present embodiment, the same operations and advantageous effects as those of the seventh embodiment can be achieved and the bus bars11can be supported by the baffle plates5and6, and thus the supporting strength of the bus bar11can be improved.

Ninth Embodiment

The ninth embodiment of the present invention will be explained based uponFIG. 18.

The present embodiment is an improvement example of the seventh embodiment and an example in which the cell holder2of the sixth embodiment is applied to the cell holder2of the prismatic battery assembly10of the seventh embodiment. The other parts of the structure are the same as those of the seventh embodiment. For this reason, parts that are the same as those of the seventh embodiment are designated by the same reference numerals of the seventh embodiment, and their description will be curtailed.

In addition, in the present embodiment, the size of the baffle plates5and6formed in the cell holder2is less than the size of the bus bar11. More specifically, the area of the baffle plates5and6in the flow direction of the cooling medium3, i.e., the area of the baffle plates5and6along the transverse direction of the cell holder2, is less than the area of the bus bar11. Such structure allows a part of the bus bar11arranged on the cooling medium outlet opening9bside of the cooling channel9to be partially cooled from the flow direction side of the cooling medium3, i.e., the upstream side of the bus bar11.

In the present embodiment, the same operations and advantageous effects as those of the seventh embodiment can be achieved and a part of the bus bar11arranged on the cooling medium outlet opening9bside of the cooling channel9can be partially cooled from the flow direction side of the cooling medium3. Due to this, the problem in the eighth embodiment of difficulty in cooling the bus bar11arranged on the cooling medium outlet opening9bside of the cooling channel9can be solved in the present embodiment.

Tenth Embodiment

The tenth embodiment of the present invention will be explained based uponFIG. 19.

In the present embodiment, an example in which a prismatic battery module100is configured using the prismatic battery assembly10of any of the first to the ninth embodiments is shown.

It is to be noted thatFIG. 19illustrates the prismatic battery assembly10of the sixth embodiment as a representative example. In addition, inFIG. 19, an illustration of the electrode terminals4of the prismatic battery cell1is curtailed.

The prismatic battery assembly10of the present embodiment is configured by vertically placing the eight prismatic battery cells1, alternately arranging the prismatic battery cells1and the cell holders2in a row, and electrically connecting the eight prismatic battery cells1in series. A cell holder2′ is arranged at the both end portions of the prismatic battery assembly10in the array direction of the prismatic battery cells1. An end surface plate110is arranged further outward of the cell holder2′. The arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110is held and fixed by four connection plates120.

The cell holder2′ is a member with irregularity on one side that electrically insulates between the prismatic battery cell1arranged at the both end portions of the prismatic battery assembly10and the end surface plate110and transmits pressure (constraint force or holding force) that has been transmitted from the end surface plate110to the prismatic battery cell1arranged at the both end portions of the prismatic battery assembly10so as to hold the prismatic battery cell1. The cell holder2′ is, similarly to the cell holder2, a plastic molding formed from an electric insulating member. More specifically, the cell holder2′ is a molding with the same size as the size of the planar portion2aof the cell holder2and an irregularity member in which, similarly to the cell holder2, the protrusions2b,2c, and2d, the baffle plates5and6, and the guide plates7and8are formed on the prismatic battery cell1side and the end surface plate110side is configured to be a plane.

When the irregularity side of the cell holder2′ is arranged on the opposite side of the prismatic battery cells1arranged at the both end portions of the prismatic battery assembly10, with the opposite side being opposite to a side arranged next to another rectangular battery cell1, the cooling channel9that is the same as the cooling channel9formed between the adjacent prismatic battery cells1is formed on the opposite side of the side next to another prismatic battery cell1of the prismatic battery cells1arranged at the both end portions of the prismatic battery assembly10.

The end surface plate110is a metal member that uniformly applies tightening force of the connection plate120to the arrangement that is constituted with the prismatic battery assembly10and the cell holder2′ from both sides of the array direction thereof. The end surface plate110has a plane with the same size as the size of the top and bottom surfaces of the prismatic battery cell1and the plane of the cell holder2′.

The connection plate120, which is a metal member that extends in the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110and spans across the two end surface plates110, is an elongated, crown-shaped plate member whose both end portions are bent at a right angle in the same direction. The four connection plates120are provided at the both end portions (four corners) of the arrangement in the flow direction of the cooling medium3so as to hold the arrangement from the direction perpendicular to the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110and the flow direction of the cooling medium3(the vertical direction ofFIG. 19), and the array direction of the arrangement (the horizontal direction ofFIG. 19). That is, the four connection plates120press the arrangement from the both sides of the array direction of the arrangement at the four corners on the opposite side of the cell holder2′ side of the end surface plate110, and press the arrangement from the direction perpendicular to the array direction of the arrangement and the flow direction of the cooling medium3. Pressure applied from the connection plates120to the end surface plates110are uniformly dispersed by the end surface plates110and transmitted to the arrangement that is constituted with the prismatic battery assembly10and the cell holders2′. This allows the eight prismatic battery cells1to be firmly held.

In the present embodiment, since the prismatic battery assembly10of any of the first to the ninth embodiments, which can improve cooling performance of the prismatic battery cell1, is mounted, the same operations and advantageous effects as those of the first to the ninth embodiments can be achieved, and downsizing of the prismatic battery module100and reliability improvement of the prismatic battery module100can be achieved.

Eleventh Embodiment

The eleventh embodiment of the present invention will be explained based uponFIG. 20.

The present embodiment is an improvement example of the tenth embodiment and differs from the tenth embodiment in the structure in which a control device130, which manages and controls a state of the electricity storage module100, is integrated with the electricity storage module100. The other parts of the structure are the same as those of the tenth embodiment. For this reason, parts that are the same as those of the tenth embodiment are designated by the same reference numerals of the tenth embodiment, and their description will be curtailed.

The control device130includes a cell control device that performs voltage detection, adjustment of the state of charge, overcharge/discharge detection, and the like of each of the eight prismatic battery cells1and a battery control device that detects charge/discharge voltage, current, and temperature at the prismatic battery assembly10, calculates the state of charge and the state of health of the prismatic battery assembly10and allowable charge/discharge electric power or current for controlling charge/discharge of the prismatic battery assembly10, and outputs this calculation information to another control device. A plurality of electronic components that constitute the cell control device and the battery control device, for instance, an integrated circuit, a microcomputer, a resistor, a semiconductor switch, a photocoupler, and the like are mounted on a wiring board and housed inside a metal case. The metal case is mounted and fixed on an upper portion of the electricity storage module100(one side of the prismatic battery module100in the direction perpendicular to the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110and the flow direction of the cooling medium3).

In the present embodiment, the same operations and advantageous effects as those of the tenth embodiment can be achieved.

Twelfth Embodiment

The twelfth embodiment of the present invention will be explained based uponFIG. 21.

The present embodiment is an improvement example of the tenth embodiment and differs from the tenth embodiment in a structure of a gas release mechanism of the prismatic battery cell1. The other parts of the structure are the same as those of the tenth embodiment. For this reason, parts that are the same as those of the tenth embodiment are designated by the same reference numerals of the tenth embodiment, and their description will be curtailed.

The prismatic battery cell1is provided with a gas release valve. The gas release valve is a safety valve that, when any abnormality occurs in the prismatic battery cell1so that electrolyte solution is evaporated and internal pressure rises, is actuated at a predetermined internal pressure and emits misty gas to the outside of the cell can1A, thereby protecting the cell can1A. The misty gas is released from the prismatic battery module100together with the cooling medium3but, depending upon the mounting position of the battery device, the misty gas may be released separately from the cooling medium3. In such case, the gas release valve of the prismatic battery cell1is connected with a gas release pipe140and, if the gas release valve is actuated, gas that has been released from the prismatic battery cell1is released to the outside though the gas release pipe140. In the present embodiment, the gas release pipe140protrudes on an upper portion of the electricity storage module100(one side of the prismatic battery module100in the direction perpendicular to the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110, and the flow direction of the cooling medium3). The gas release pipes140are arranged in a row in the array direction of the prismatic battery cells1corresponding to the array of the prismatic battery cells1.

In the present embodiment, the same operations and advantageous effects as those of the tenth embodiment can be achieved.

Thirteenth Embodiment

The thirteenth embodiment of the present invention will be explained based uponFIG. 22.

The present embodiment is an improvement example of the tenth embodiment and an example in which the eleventh embodiment and the twelfth embodiment are combined. The other parts of the structure are the same as those of the tenth embodiment. For this reason, parts that are the same as those of the tenth embodiment are designated by the same reference numerals of the tenth embodiment, and their description will be curtailed.

In the present embodiment, the gas release pipes140shown in the twelfth embodiment are arranged on an upper portion of the prismatic battery module100(one side of the prismatic battery module100in the direction perpendicular to the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110, and the flow direction of the cooling medium3) and the control device130shown in the eleventh embodiment is arranged on a lower portion of the prismatic battery module100(the other side of the prismatic battery module100in the direction perpendicular to the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110, and the flow direction of the cooling medium3).

The gas release pipes140are covered by a gas release duct150that extends in the array direction of the arrangement that is constituted with the prismatic battery assembly10, the cell holders2′, and the end surface plates110(for ease of comprehension, a gas release pipe140is illustrated as viewable from the gas release duct150but in practice, the end surface of the gas release duct150is covered by a wall). A gas outlet pipe160is provided at the end of one side of the gas release duct150. Gas released from the gas release pipes140to the gas release duct150is guided and released to the outside of the vehicle through the gas outlet pipe160.

In the present embodiment, the same operations and advantageous effects as those of the tenth embodiment can be achieved.

Although the variety of embodiments and examples of variations are described above, the present invention is not to be limited only to those contents. The scope of the present invention includes other possible embodiments invented within the scope of the technical idea of the present invention.