JP2017091989A - Battery unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery unit capable of effectively cooling an inter-block bus bar.SOLUTION: A battery unit 10 comprising a plurality of cylindrical cells each including a positive electrode and a negative electrode in both ends in an axial direction comprises: a plurality of battery blocks configured by connecting two or more battery cells in parallel; a resin case 16 surrounding the plurality of battery cells, the resin case 16 including an outlet opening 36 of cooling air for cooling the plurality of battery cells on its peripheral surface; a plurality of inter-cell bus bars each electrically connecting positive electrodes or negative electrodes of two or more battery cells belonging to the same battery block with each other; and an inter-block bus bar 26 for connecting the inter-cell bus bar connecting the positive electrodes of one battery block with each other and the inter-cell bus bar connecting the negative electrode of the other neighboring battery block with each other. The inter-block bus bar 26 passes outside of the resin case 16 in such a manner that the inter-block bus bar partially opposes the outlet opening 36.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery unit including a plurality of cylindrical battery cells each provided with a positive electrode and a negative electrode at both axial ends.

  Conventionally, a battery unit including a plurality of cylindrical battery cells is known. For example, Patent Document 1 discloses a battery unit in which a plurality of cylindrical battery cells are held by a module base made of metal. As in Patent Document 1, by holding a plurality of battery cells with a metal member (module base), the heat of the battery cells is evenly distributed through the metal member. Variations in temperature can be reduced. Moreover, in patent document 1, cooling of a battery cell is aimed at by applying cooling air to a battery cell.

JP 2010-0113999 A

  By the way, some battery units are known in which a plurality of cylindrical battery cells are divided into several blocks. In such a battery unit, positive and negative electrodes of two or more battery cells are connected in parallel by inter-cell bus bars to form one battery block, and the battery blocks are connected in series by inter-block bus bars.

  In the battery unit having such a configuration, a large current flows through the inter-block bus bar connecting the battery blocks in series, and a large Joule heat is generated. Then, due to the Joule heat, the inter-block bus bar becomes high temperature, which causes problems such as a rise in the temperature of the battery cells in the vicinity of the inter-block bus bar.

  In the conventional technology such as Patent Document 1, cooling of the battery cell itself is considered, but cooling of the bus bar connecting the battery cells in series is not considered. Therefore, an object of the present invention is to provide a battery unit that can effectively cool the inter-block bus bar.

  The battery unit of the present invention is a battery unit including a plurality of cylindrical battery cells each provided with a positive electrode and a negative electrode at both ends in the axial direction, and a plurality of batteries configured by connecting two or more battery cells in parallel. A block, a holder for holding the plurality of battery cells in a state in which the directions of the positive electrode and the negative electrode are aligned, and a case surrounding the periphery of the plurality of battery cells held by the holder, A case provided with an outlet opening for cooling air for cooling a plurality of battery cells, and a plurality of inter-cell bus bars, each of which electrically connects positive electrodes or negative electrodes of two or more battery cells belonging to the same battery block. Inter-cell bus bar and a plurality of inter-block bus bars, each connecting an inter-cell bus bar connecting the positive electrodes of one battery block, and the negative electrode of another adjacent battery block An inter-cell bus bar for connecting an operator, and an inter-block bus bar for connecting the operator, wherein the inter-block bus bar passes outside the case so that a part of the bus bar faces the outlet opening. And

  According to the present invention, a part of the inter-block bus bar faces the outlet opening, so that the cooling air easily hits the inter-block bus bar. As a result, the inter-block bus bar is effectively cooled by the cooling air.

It is a perspective view of the battery unit which is embodiment of this invention. It is a side view of a battery unit. It is a perspective view which shows the state which hold | maintained the battery cell with the battery holder. It is a top view of a bus bar between cells. It is AA sectional drawing of FIG.

  Hereinafter, the battery unit 10 which is embodiment of this invention is demonstrated with reference to drawings. FIG. 1 is a perspective view of a battery unit 10 according to an embodiment of the present invention. 2 is a side view of the battery unit 10, FIG. 3 is a perspective view of the battery holder 14 holding the battery cells 12, FIG. 4 is a plan view of the inter-cell bus bar 24 on the negative electrode side, and FIG. It is AA sectional drawing of 2.

  The battery unit 10 includes a plurality of cylindrical battery cells 12. The battery cell 12 is a chargeable / dischargeable secondary battery, such as a nickel hydride battery or a lithium ion battery housed in a cylindrical case. A positive electrode and a negative electrode that are electrodes of the battery cell 12 are provided at both axial ends of the battery cell 12. The battery unit 10 illustrated in FIG. 2 has 60 battery cells 12, and the 60 battery cells 12 are arranged in an array of 4 columns and 15 rows. The 60 battery cells 12 are divided into blocks every 15 cells to form four battery blocks. Fifteen battery cells 12 belonging to the same battery block are connected in parallel by an inter-cell bus bar 24 described later. A battery block in which 15 battery cells 12 are connected in parallel is connected in series to another battery block by an inter-block bus bar 26 described later.

  On the negative electrode side end face of the battery cell 12, a discharge valve (not shown) that allows release of gas generated in the battery cell 12 is provided. The configuration of the discharge valve is not particularly limited as long as it can be opened when the internal pressure of the battery cell 12 increases. The discharge valve can be configured, for example, by locally thinning the outer case of the battery cell 12. When gas is generated inside the battery cell 12 due to overcharge, overdischarge, short circuit, or the like, and the internal pressure of the battery cell 12 increases, the discharge valve (thin portion) breaks, and the gas flows into the battery cell 12. To the outside.

  Each battery cell 12 is held upright with the directions of the positive electrode and the negative electrode aligned. In the present embodiment, the battery cell 12 is held in an upright posture with the end face with the positive electrode facing upward. Each battery cell 12 is accommodated in the accommodation hole 15 provided in the battery holder 14 at the lower end thereof, and held by the battery holder 14. The battery holder 14 has a substantially plate shape, and the accommodation holes 15 are two-dimensionally arranged on the plate plane. In this embodiment, the accommodation holes 15 are arranged in an array of 4 columns and 15 rows, and the accommodation holes 15 in the adjacent columns are arranged so as to be shifted by a half pitch.

  Each accommodation hole 15 has a round hole shape that fits into the cylindrical shape of the battery cell 12, and the battery cell 12 is inserted into the round hole and held upright by the battery holder 14. The length of the accommodation hole 15 in the central axis direction is sufficiently long so that the held battery cell 12 does not wobble. The accommodation hole 15 penetrates the battery holder 14 in the plate thickness direction, and the lower end of the battery cell 12 is exposed downward. The battery holder 14 is made of a high heat transfer material such as aluminum in order to evenly disperse the generated heat and reduce temperature variations between the battery cells 12.

  The periphery of the plurality of battery cells 12 held by the battery holder 14 is covered with a resin case 16. The resin case 16 has a substantially box shape with a completely open bottom, and has a ceiling plate 30 (see FIG. 5) in the vicinity of the upper end thereof. The ceiling plate 30 is provided with holding openings 32 respectively corresponding to the arranged battery cells 12. Further, the upper part of the resin case 16 is covered with an upper cover 18.

  An inlet opening 34 (see FIG. 5) and an outlet opening 36 (see FIGS. 1, 2, and 5) are formed on the peripheral surface of the resin case 16. The inlet opening 34 is an opening for allowing cooling air for cooling the battery cells 12 to flow into the battery unit 10. The inlet opening 34 is provided on one side wall of the resin case 16. The inlet openings 34 are slit holes that are elongated in the height direction, and a plurality of inlet openings 34 are provided at intervals in the longitudinal direction.

  The outlet opening 36 is an opening for releasing cooling air that has flowed into the battery unit 10 to the outside. The outlet opening 36 is provided on the side wall opposite to the inlet opening 34 across the plurality of battery cells 12. The outlet opening 36 is a slit hole elongated in the longitudinal direction. A plurality of outlet openings 36 are two-dimensionally arranged on the side wall of the resin case 16. An upper end edge and a lower end edge of the outlet opening 36 protrude outward and constitute a rib 38.

  An exhaust cover 20 is disposed below the battery holder 14. The exhaust cover 20 has a substantially boat shape with a peripheral edge raised upward. Between the battery holder 14 and the exhaust cover 20, an exhaust passage 28 through which the gas released from the battery cell 12 flows is formed. The gas discharged from the battery cell 12 to the exhaust passage 28 is discharged to the outside of the battery unit 10 and guided to an appropriate position by a duct or the like.

  On both sides of the battery cell 12 in the axial direction, inter-cell bus bars 24 that electrically connect the positive electrodes or the negative electrodes of the battery cells 12 are provided. The configuration of the inter-cell bus bar 24 on the positive electrode side and the inter-cell bus bar 24 on the negative electrode side are substantially the same. Therefore, hereinafter, only the configuration of the inter-cell bus bar 24 on the negative electrode side will be described with reference to FIG.

  Below the battery holder 14, the same number of inter-cell bus bars 24 as the battery blocks, that is, four inter-cell bus bars 24 are provided. The four inter-cell bus bars 24 are integrated with a resin 43 (see FIG. 5) while maintaining an insulation with a space therebetween.

  Each inter-cell bus bar 24 electrically connects the negative electrodes of the 15 battery cells 12 constituting one battery block. The inter-cell bus bar 24 is a flat plate member made of a conductive material such as copper. The inter-cell bus bar 24 is provided with through openings 40 corresponding to the arranged battery cells 12. One through opening 40 is provided for each battery cell 12 so that the lower end surface of the corresponding battery cell 12 is exposed to the exhaust passage 28. The gas released from the battery cell 12 passes through the through opening 40 and reaches the exhaust passage 28.

  A connection piece 42 that is a part of the inter-cell bus bar 24 is located in the through opening 40. The connection piece 42 has a leaf spring shape with appropriate elasticity, and is inclined so as to approach the negative electrode of the battery cell 12 as it approaches the tip. And the front-end | tip of all the connection pieces 42 contacts the negative electrode of the corresponding battery cell 12, and connects the negative electrodes of these 15 battery cells 12 electrically. One end in the width direction of the inter-cell bus bar 24 is bent upward to form a bent portion 44. The bent portion 44 is a portion connected to the inter-block bus bar 26 on the outside of the resin case 16.

  Above the battery cell 12, a positive-side inter-cell bus bar 24 having the same shape as the negative-side inter-cell bus bar is disposed. The inter-cell bus bar 24 on the positive electrode side also electrically connects the positive electrodes of the 15 battery cells 12 constituting one battery block. Then, the 15 battery cells 12 constituting one battery block are connected in parallel by the inter-cell bus bar 24 on the negative electrode side and the positive electrode side.

  The four battery blocks are connected in series by an inter-block bus bar 26. Specifically, the inter-block bus bar 26 electrically connects the positive-side inter-cell bus bar 24 connected to one battery block and the negative-side inter-cell bus bar 24 connected to another adjacent battery block. Connect to. The inter-block bus bar 26 is a substantially flat plate member made of a conductive material such as copper, and is disposed outside the resin case 16 as shown in FIGS. 1, 2, and 5. The inter-block bus bar 26 has its upper end connected to the inter-cell bus bar 24 on the positive side of one battery block and its lower end connected to the inter-cell bus bar 24 on the negative side of the adjacent battery block. As it progresses (right side in FIG. 2), it has a substantially parallelogram shape that proceeds downward (negative electrode side). Further, the width of the inter-block bus bar 26 is substantially the same as that of the bent portion 44 standing from the end of the inter-cell bus bar 24. The inter-block bus bar 26 is formed, for example, by pressing a thin metal plate and punching it into a desired shape. In the present embodiment, a metal thin plate that is sufficiently wider than the final width of the inter-block bus bar 26 is prepared, and the inter-block bus bar 26 is configured by folding both ends of the metal thin plate in the width direction toward the center in the width direction. Has been.

  The inter-block bus bar 26 of the present embodiment is arranged such that a part thereof faces the outlet opening 36. With this configuration, the cooling air supplied to the battery unit 10 can easily hit the inter-block bus bar 26. Further, in the present embodiment, ribs 38 standing from the upper and lower edges of the outlet opening 36 are brought into contact with the inter-block bus bar 26. With this configuration, a flow path surrounded by the inter-block bus bar 26 and the rib 38 is configured.

  Here, the reason for adopting such a configuration will be described. Even in the conventional battery unit, an inlet opening 34 and an outlet opening 36 for cooling air are formed on the peripheral surface of the resin case 16. Conventionally, the inter-block bus bar 26 has a position and shape that do not overlap with the outlet opening 36 so as not to hinder the discharge of cooling air from the outlet opening 36. In this case, the inter-block bus bar 26 has to be relatively narrow.

  However, a relatively large current normally flows through the inter-block bus bar 26 that connects battery blocks in series. If the current value is large, the generated Joule heat is correspondingly increased, and the inter-block bus bar 26 is likely to be hot. If the inter-block bus bar 26 becomes hotter than the battery cell 12, the temperature of the battery cell 12 in the vicinity of the inter-block bus bar 26 rises, causing a variation in temperature between the battery cells 12. It was.

  Therefore, in the present embodiment, the inter-block bus bar 26 is set to a position and size that overlaps the cooling air outlet opening 36, and the inter-block bus bar 26 is easily hit by the cooling air. In such a configuration, the inter-block bus bar 26 is effectively cooled by the cooling air, and the inter-block bus bar 26 can be prevented from becoming hotter than the battery cell 12. In addition, the cooling air discharged | emitted from the exit opening 36 is a wind after heat-exchanging with the battery cell 12, and temperature is comparatively high. However, since the temperature of the inter-block bus bar 26 is usually higher than that of the battery cell 12, the inter-block bus bar 26 can be sufficiently cooled even with cooling air after heat exchange with the battery cell 12.

  Further, as described above, in this embodiment, the inter-block bus bar 26 is brought into contact with the rib 38 of the outlet opening 36. Therefore, the cooling air flows along a narrow flow path surrounded by the inter-block bus bar 26 and the rib 38. When the cooling air flows through the narrow flow path, the wind speed of the cooling air increases, and the heat transfer efficiency between the inter-block bus bar 26 and the cooling air can be improved. As a result, the inter-block bus bar 26 can be cooled more effectively. Further, by bringing the inter-block bus bar 26 into contact with the rib 38 protruding from the resin case 16, heat transfer from the inter-block bus bar 26 to the resin case 16 is promoted, and the cooling efficiency of the inter-block bus bar 26 can be further improved. .

  In the present embodiment, the inter-block bus bar 26 has a shape overlapping with the outlet opening 36. As a result, the inter-block bus bar 26 can be made wider than in the prior art. As the inter-block bus bar 26 becomes wider and the cross-sectional area increases, the electrical resistance decreases accordingly. By reducing the electrical resistance, the amount of heat generated by energization can be reduced, and overheating of the inter-block bus bar 26 can be more effectively prevented.

  The configurations described above are only examples, and other configurations may be appropriately changed as long as the inter-block bus bar 26 faces the outlet opening 36. In the present embodiment, the inlet opening 34 and the outlet opening 36 are provided on the two opposing surfaces of the resin case 16, but the positions of these openings may be changed as appropriate. For example, the inlet opening 34 may be provided at the front end or the rear end of the resin case 16, and the outlet openings 36 may be provided on both side surfaces of the resin case 16. Further, the shape of the inter-block bus bar 26 may be appropriately changed as long as adjacent battery blocks can be connected in series. For example, the inter-block bus bar 26 may not be a substantially parallelogram, but may be a substantially L shape that is bent halfway.

  DESCRIPTION OF SYMBOLS 10 Battery unit, 12 Battery cell, 14 Battery holder, 15 Housing hole, 16 Resin case, 18 Upper cover, 20 Exhaust cover, 24 Bus bar between cells, 26 Bus bar between blocks, 28 Exhaust passage, 30 Ceiling plate, 32 Holding opening, 34 inlet opening, 36 outlet opening, 38 rib, 40 through opening, 42 connection piece, 44 bent part.

Claims (1)

A battery unit including a plurality of cylindrical battery cells each provided with a positive electrode and a negative electrode at both ends in the axial direction,
A plurality of battery blocks configured by connecting two or more battery cells in parallel;
A holder for holding the plurality of battery cells in a state in which the directions of the positive electrode and the negative electrode are aligned;
A case that surrounds a plurality of battery cells held by the holder, and a case provided with an outlet opening for cooling air that cools the plurality of battery cells on a peripheral surface thereof;
A plurality of inter-cell bus bars each of which electrically connects positive or negative electrodes of two or more battery cells belonging to the same battery block;
A plurality of inter-block bus bars, each connecting an inter-cell bus bar that connects positive electrodes of one battery block and an inter-cell bus bar that connects negative electrodes of other adjacent battery blocks. When,
With
The inter-block bus bar passes through the outside of the case so that a part thereof faces the outlet opening.
A battery unit characterized by that.