JP5162919B2 - Power storage unit - Google Patents

Description

  The present invention relates to a power storage unit mainly used as an auxiliary power source for a vehicle.

  In recent years, automobiles (hereinafter referred to as vehicles) equipped with a hybrid system and an idling stop system have been rapidly developed from the viewpoint of protecting the global environment. Along with this, systems that regenerate braking energy of vehicles as electrical energy, Various proposals have been made on a system for assisting the motor drive of a hybrid vehicle during acceleration or the like.

  In such a system, in the case of regeneration, it is necessary to store braking energy that changes abruptly as much as possible in the energy storage element as electric energy, and in the case of motor drive assistance, it is necessary to supply a large current that can rapidly accelerate the vehicle. In any case, a system using a capacitor, which is superior in quick charge / discharge characteristics as compared with a battery, is attracting particular attention as a storage element.

  However, in order to store electric power that can accelerate the vehicle rapidly, an electric double layer capacitor having a large capacity, for example, is required. Further, since the charging voltage of this capacitor is as low as about 2.2V, a large number of capacitors are connected to the voltage. It is necessary to raise.

A configuration example in which a large number of power storage elements are held and connected as described above is described in Patent Document 1. This is an example of a power storage unit using a cylindrical battery as a power storage element. As shown in FIG. 6, the cylindrical battery 1 (shown in a perspective view) is connected to the battery holes 2a of the upper and lower supports 2 at both ends. It is held by inserting. At this time, since a step is provided in the battery hole 2a as shown in the lower support body 2 in FIG. 6, the battery hole 2a can be fixed by contacting the peripheral portions of both ends of the cylindrical battery 1 with the step. The support 2 is provided with electrode holes 2b, and the electrodes provided at both ends of the cylindrical battery 1 are exposed through the electrode holes 2b. The exposed electrodes are connected by a connection plate (bus bar) (not shown). The connection plate is accommodated in the groove 2c. With such a configuration, a power storage unit capable of simultaneously holding a large number of power storage elements can be obtained.
Japanese Patent No. 3777748

  Such a power storage unit can certainly hold a large number of power storage elements. However, when such a power storage unit is mounted on a vehicle, there are the following problems.

  The cylindrical battery 1 that is a power storage element has a structure in which, for example, a battery material is put into a bottomed cylinder and the upper part is sealed with an electrode lid. In this case, since the bottomed cylinder is generally manufactured by deep drawing using a press, the error of the cylinder diameter is small. On the other hand, when sealing with an electrode lid, two members (bottomed cylinder and electrode lid) are overlapped and caulked at the same time, so in addition to the dimensional error of each member, an error due to the caulking process is added. The height error of the cylindrical battery 1 becomes larger than the error of the cylindrical diameter.

  When a plurality of cylindrical batteries 1 having large errors in the height direction are inserted and held in the support 2 shown in FIG. 6, the step of the battery hole 2a is fixed. The interval is determined by the highest cylindrical battery 1. Therefore, the other cylindrical battery 1 cannot be reliably brought into contact with the step of the battery hole 2a, and is held in a state where a gap corresponding to the height error is generated. In this state, the cylindrical battery 1 is connected by the connection plate, so the cylindrical battery 1 having a low height is held in a so-called suspended state by the upper and lower connection plates.

  When a vehicle vibration is applied to the power storage unit, the cylindrical battery 1 having a low height has a gap between the step of the battery hole 2a, and thus the cylindrical battery 1 vibrates in the height direction within the gap. become. Since this vibration stress is applied to the connection part of the electrode and the connection plate and the connection plate itself, there is a possibility that the contact resistance of the connection part will increase and heat will be generated, and the connection plate may gradually cause fluctuating stress fatigue. As a result, there existed a subject that reliability fell.

  An object of the present invention is to solve the conventional problems described above, and to provide a highly reliable power storage unit that can reliably hold a power storage element having a height error.

In order to solve the above-described conventional problems, the power storage unit of the present invention has a column shape, and includes a plurality of power storage elements having an end surface electrode provided on one end surface of the column shape and a side electrode provided on a side surface as electrodes. And when the plurality of power storage elements are arranged and electrically and mechanically connected to each other, the power storage element having the side electrode that is either the highest voltage or the lowest voltage among the plurality of power storage elements. together are welded connected to the side electrode of the other of said power storage device except a bus bar part is welded and connected to the end face electrode of the electricity storage device of the next, the coercive Jiana the bottom is to be inserted in the storage element A lower case, and an upper case in which an upper portion of the power storage element is inserted and a contact portion with a part of the periphery of the end face having the end face electrode is provided. of the bottom side To the bottom and contact with the elastic portion of the electric storage element is provided, the displacement width of the elastic portion is made larger than the height error of a plurality of the storage element.

  According to the present invention, since the elastic part provided in the lower case comes into contact with the bottom of the power storage element by inserting the power storage element into the lower case, the height error of the power storage element can be absorbed by the elastic part when assembled. As a result, even if there is a height error, all the power storage elements can be held and fixed, so that the influence of the vibration on the connection portion between the electrode and the bus bar and the bus bar itself can be reduced and high reliability can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a partially exploded perspective view of a power storage unit according to an embodiment of the present invention. FIG. 2 is a perspective view of a power storage element and a bus bar of the power storage unit in the embodiment of the present invention. FIG. 3 is a perspective view of a state in which the bent bar of the power storage unit according to the embodiment of the present invention is attached to the power storage element. FIG. 4 is a completed perspective view of the power storage unit according to the embodiment of the present invention. FIG. 5 is a cross-sectional view of the power storage unit in the embodiment of the present invention. Note that in this embodiment, a configuration example of a power storage unit for a vehicle will be described.

  In FIG. 1, a power storage element 11 that stores electric power is, for example, a cylindrical electric double layer capacitor having a diameter of 3 cm. The manufacturing method of the electrical storage element 11 is the same as that of the conventional cylindrical battery. Therefore, an end surface peripheral portion 13 that is raised by the caulking process is formed on one end surface (the upper surface in FIG. 1) of the power storage element 11. In addition, the cylindrical side surface of the electricity storage element 11 is made of aluminum, and is connected internally so as to be a negative electrode. Accordingly, the entire cylindrical side surface of the electricity storage element 11 forms the side electrode 15. Further, the end face is an aluminum lid, and a semicircular end face electrode 17 having a height higher than that of the end face peripheral portion 13 is formed by press-molding the lid. The end face electrode 17 is internally connected so as to be a positive electrode. Therefore, an insulating member (not shown) is caulked between the cylindrical portion and the lid portion of the electricity storage element 11. A pressure regulating valve 19 is provided at a position other than the end face electrode 17 in the lid portion. The pressure regulating valve 19 is used to release the electrolyte filled in the electric storage element 11 when it vaporizes. Thereby, the internal pressure rise of the electrical storage element 11 can be prevented.

  Next, a description will be given of the bus bar 21 used when a plurality of such power storage elements 11 are arranged and electrically and mechanically connected to each other. The bus bar 21 is made of the same aluminum as the side electrode 15 and the end electrode 17. Note that these may be other metals as long as they are the same metal, but since the internal electrode of the electric double layer capacitor is made of aluminum, when the internal electrode is welded to the side electrode 15 or the end surface electrode 17, Is also made of aluminum. Therefore, as will be described later, the bus bar 21 is also made of aluminum because welding is performed when the bus bar 21 is joined to the side electrode 15 or the end electrode 17. Further, by using the same metal, not only the weldability is improved, but also the corrosion resistance is improved because a local battery is not formed by moisture.

  As shown in FIG. 2, the bus bar 21 has a circumferential portion that fits into the side surface of the power storage element 11 and a flat portion that is welded to the end surface electrode 17 of the adjacent power storage element 11. It is obtained by press molding a 5 mm aluminum plate. As shown in FIG. 3, the shape of the bus bar 21 may be provided with a bent portion 23 between a portion (flat portion) connected to the end face electrode 17 and a portion (circumferential portion) connected to the side electrode 15. . In addition, the bending part 23 is easier to process if it is provided on the flat part side. The role of the bent portion 23 will be described later.

  The bus bar 21 is fitted into the side surface of the power storage unit 11 in the direction shown in FIG. 1 and is connected to the side electrode 15 by laser welding in order to obtain a reliable electrical and mechanical connection. The laser welding site is indicated by a cross in FIG. In FIG. 1, multiple points are welded in a spot shape, but this may be welded in a linear shape by sequentially shifting the welding position. In this case, the connection reliability is improved as compared with the spot shape. In this way, the storage element 11 integrated with the bus bar 21 is formed.

  Note that the bus bar 21 is connected to other power storage elements 11 except for the power storage element 11 having the side electrode 15 that has either the highest voltage or the lowest voltage among the plurality of power storage elements 11. That is, in the present embodiment, as shown in FIG. 1, five power storage elements 11 are connected in series, and the side electrode 15 is a negative electrode and the end surface electrode 17 is a positive electrode. When connected in series, the side electrode 15 of the foremost power storage element 11 in FIG. 1 has the lowest voltage. Accordingly, the bus bar 21 is connected to the other four power storage elements 11 except the frontmost power storage element 11. When the internal connection of the power storage element 11 is reversed, the side electrode 15 of the frontmost power storage element 11 has the highest voltage. Even in this case, the structure of the power storage unit is the same only by reversing the positive electrode and the negative electrode.

  Instead of the bus bar 21, a negative electrode terminal bus bar 25 is connected to the foremost power storage element 11. The configuration of the negative electrode terminal bus bar 25 is substantially the same as that of the bus bar 21, but since there is no adjacent power storage element 11, a portion connected to the end face electrode 17 becomes unnecessary. However, in order to make an electrical connection to the outside of the power storage unit, the negative terminal bus bar 25 is provided with a screw hole 27 for connecting to a power line or an external bus bar described later. Moreover, in order to make it easy to connect with an electric power line or an external bus bar, the bending process is given so that it may fit in the edge part of the upper case mentioned later. This portion is not limited to the structure shown in FIG. 1, and may be appropriately changed depending on the shape of the power storage unit, the power line, and the like. Note that the connection between the side electrode 15 of the foremost power storage element 11 and the negative terminal bus bar 25 is welded in the same manner as when the bus bar 21 is connected to another power storage element 11.

  In this way, the bottom 29 of the power storage element 11 to which the bus bar 21 or the negative terminal bus bar 25 is welded is inserted into the holding hole 33 provided in the lower case 31. The lower case 31 is made of resin, and an elastic portion 35 is integrally formed on the bottom surface of the holding hole 33. Further, the diameter of the holding hole 33 is, for example, about 0.1 to 0.2 mm larger than the outer diameter of the power storage element 11 so that the power storage element 11 can be smoothly stored.

  As shown in FIG. 1, the elastic portion 35 has a cantilever shape and is formed so that the tip thereof is higher than the bottom surface of the holding hole 33. Therefore, when the bottom portion 29 of the power storage element 11 comes into contact with the elastic portion 35, the power storage element 11 is pushed upward. Note that the height from the bottom surface of the holding hole 33 at the tip of the elastic portion 35 corresponds to the displacement width of the elastic portion 35, but this should be larger than the height error of the plurality of power storage elements 11 obtained in advance. is there. In FIG. 1, the elastic portions 35 are provided at four locations. However, the elastic portions 35 may be more or less than four locations as long as they have elasticity capable of holding the power storage element 11. However, at least one is necessary. Also, the shape of the elastic portion 35 is such that the tip of the cantilever becomes higher toward the center of the bottom surface of the holding hole 33, but this also has a reverse direction (higher toward the periphery of the bottom surface), an oblique direction, You may arrange | position in the circumferential direction. Furthermore, the elastic portion 35 may be configured separately from the lower case 31 and an elastic material such as a spring may be disposed on the bottom surface of the holding hole 33, but in this case, the elasticity of the elastic material may vary. Therefore, it is desirable to form them integrally because elastic variation can be reduced.

  In addition, a fixing rod 37 is attached in advance to the lower case 31 in order to be firmly fixed to an upper case described later. In the present embodiment, four fixing rods 37 are used. The fixing rod 37 is formed with female screws at both ends, while the lower case 31 is provided with a fixing screw hole 39. Therefore, the lower case 31 and the fixing rod 37 are fixed by tightening the fixing screw 41 in a state where the fixing rod 37 is arranged at the position of the fixing screw hole 39. At this time, for example, the fixing screw 41 is a countersunk screw so that the head of the fixing screw 41 does not protrude from the lower case 31.

  Next, when the power storage element 11 is inserted into the holding hole 33 of the lower case 31, the flat portion of the bus bar 21 needs to be covered with the end face electrode 17 of the adjacent power storage element 11, so that as shown in FIG. It inserts from the electrical storage element 11 toward the back in order. As a result, the flat portion of the bus bar 21 connected to the adjacent power storage element 11 contacts the end face electrode 17. However, the end electrode 17 of the innermost power storage element 11 in FIG. 1 does not have the adjacent power storage element 11, so the bus bar 21 is not covered. A positive terminal bus bar, which will be described later, is connected to this, which will be described later.

  After the storage element 11 is inserted into the lower case 31, the upper part 45 of the storage element 11 is inserted into the upper case 43. The upper case 43 has a “B” shape when viewed from above so that the bus bar 21 and the pressure regulating valve 19 are exposed. Further, the upper case 43 is provided with a contact portion 47 with which a part of the end surface peripheral portion 13 of the power storage element 11 contacts. Since the contact portion 47 is integrally formed with the upper case, the contact portion 47 serves as a reference for the fixed position of each power storage element 11. The upper case 43 is also provided with a fixing screw hole 39 similar to that of the lower case 31 for mechanical connection with the fixing rod 37. Further, an insert nut 49 is embedded at a position facing the screw hole 27 of the negative terminal bus bar 25. In addition, since the end surface electrode 17 provided in the innermost power storage element 11 in FIG. 1 has the highest voltage, a positive terminal bus bar 51 is attached to perform external wiring here, but the positive terminal bus bar 51 also has a negative terminal. A screw hole (not shown) similar to the screw hole 27 of the bus bar 25 is provided. Therefore, an insert nut (not shown) is also embedded at a position facing the screw hole of the positive terminal bus bar 51. Further, since the upper case 43 is made of the same resin as the lower case 31, the above-described components are integrally formed by injection molding.

  When the upper portion 45 of the power storage element 11 is inserted into the upper case 43, a part of the end surface peripheral portion 13 of the power storage element 11 comes into contact with the contact portion 47. However, since the elastic portion 35 pushes the power storage element 11 upward in FIG. 1, a gap is generated between the upper case 43 and the fixing rod 37 accordingly. Here, the fixing screw 41 is tightened in a state where the upper case 43 is pushed down so that the gap is eliminated. As a result, the upper case 43 and the lower case 31 are connected and fixed.

  The state assembled so far is shown in FIG. Since the bus bar 21 covers the end face electrode 17 of the adjacent power storage element 11, the bus bar 21 is laser-welded to be electrically and mechanically connected. At this time, since the height of the end face electrode 17 is higher than that of the end face peripheral portion 13, the bus bar 21 does not come into contact with the end face peripheral portion 13 to be short-circuited. Further, although the laser welding portion is indicated by a cross mark in FIG. 4, similarly to the laser welding with respect to the side electrode 15, it may be welded in a spot-like manner or in a linear manner.

  At this time, the end face electrode 17 of the innermost storage element 11 in FIG. 4 is covered with the positive terminal bus bar 51, and this is also laser-welded in the same manner as the other bus bars 21. Thereby, external wiring can be performed on the positive terminal bus bar 51. On the other hand, as shown in FIG. 4, since the bent portion of the negative terminal bus bar 25 is fitted to the upper case 43, external wiring can also be performed on the negative terminal bus bar 25. In the present embodiment, external wiring is performed by the external bus bar 53. The external bus bar 53 is made of copper having a thickness of 1 mm, and a bent portion 55 is integrally formed at a part thereof. The bent portion 55 is for absorbing stress due to vibration or thermal expansion when the external bus bar 53 is fixed. A screw hole 57 for fixing the screw is also provided. Accordingly, the external bus bar 53 is arranged so that the screw hole 57 is aligned with the screw hole 27 of the negative terminal bus bar 25 and the screw 59 is fastened to the insert nut 49 together with the washer 60, whereby the external bus bar 53 and the negative terminal bus bar 25 are connected. Electrically connected. This is similarly connected to the positive terminal bus bar 51. Although omitted in FIG. 4, the other end of the external bus bar 53 is connected to another power storage unit 61. Thereby, many more electrical storage units 61 can be connected.

  The adjacent power storage elements 11 have a gap when inserted into the upper case 43 and the lower case 31. Thereby, since the flat part of the bus bar 21 becomes longer by the gap, the displacement of the bus bar 21 is facilitated. As a result, since the bus bar 21 can be easily displaced when the power storage element 11 is pushed in by the contact portion 47, the influence of pressing of the other power storage elements 11 by the bus bar 21 can be reduced. Can be fixed more independently. As shown in FIG. 3, if the bent portion 23 is provided in the bus bar 21, it is possible to further absorb the influence of pressing the other power storage element 11 by the bus bar 21. In addition, the bent portion 23 also has a role of absorbing stress due to vibration or thermal expansion when the bus bar 21 is fixed, like the bent portion 55 described above.

  Here, FIG. 5 shows a cross-sectional view of a portion indicated by a dotted line in FIG. When the upper case 43 is fastened to the fixing rod 37 with the fixing screw 41, a part of the end surface peripheral portion 13 of the power storage element 11 is pushed down by the contact portion 47. Thereby, the bottom part 29 of the electrical storage element 11 is fixed by pushing down the elastic part 35. Since the displacement width of the elastic portion 35 at this time is larger than the height error of the power storage element 11 as shown in FIG. 5, it is assumed that there is an error in the height of the power storage element 11 with reference to the contact portion 47. However, the error can be absorbed by changing the displacement amount of the elastic portion 35. Therefore, all the power storage elements 11 can be reliably fixed, the vehicle vibration stress to the welded connection portion and the bus bar 21 is reduced, and high reliability is obtained.

  With the above-described configuration and operation, the elastic portion 35 absorbs the height error of the power storage element 11, so that heat generation at the welded connection portion and fluctuating stress fatigue of the bus bar 21 are reduced, and a power storage unit with high reliability can be realized. .

  In this embodiment, the screw 59 is tightened with the insert nut 49. However, this is because the nut housing portion having an inner width with which the nut abuts is integrated with the upper case 43 at a position facing the screw hole 27. It is good also as a structure which provides by molding and accommodates a nut in a nut accommodating part. In this case, since the corners of the nut come into contact with the wall surface of the inner width portion of the nut storage portion, the screw 59 can be tightened without causing the nut to idle. The same configuration may be provided on the positive electrode terminal bus bar 51 side.

  In the present embodiment, power storage element 11 has been described as having a cylindrical shape, but this may be a prismatic shape. Furthermore, although the structure using the electric double layer capacitor for the power storage element 11 has been described, this may be another capacitor such as an electrochemical capacitor, a secondary battery, or the like.

  In the present embodiment, the case where the power storage unit is applied to a vehicle has been described. However, the present invention is not limited to this, and can be applied to a general emergency auxiliary power source or the like.

  The power storage unit according to the present invention has a configuration in which the elastic portion absorbs the height error of the power storage element, so that heat generation at the welded connection portion and fluctuating stress fatigue of the bus bar can be reduced, and high reliability is obtained. It is useful as a power storage unit used for an auxiliary power source for vehicles.

The partial exploded perspective view of the electrical storage unit in embodiment of this invention The perspective view of the electrical storage element and bus bar of the electrical storage unit in embodiment of this invention The perspective view of the state which attached the bus-bar with a bending part of the electrical storage unit in embodiment of this invention to the electrical storage element The completed perspective view of the electrical storage unit in embodiment of this invention Sectional drawing of the electrical storage unit in embodiment of this invention A perspective view of a conventional power storage unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Power storage element 13 End surface peripheral part 15 Side electrode 17 End surface electrode 21 Bus bar 23 Bending part 29 Bottom part 31 Lower case 35 Elastic part 37 Fixing rod 39 Fixing screw hole 41 Fixing screw 43 Upper case 45 Upper part 47 Contact part

Claims (7)

A plurality of power storage elements having a column shape and having an end surface electrode provided on one end surface of the column shape as an electrode and a side electrode provided on a side surface;
When the plurality of power storage elements are arranged side by side and electrically and mechanically connected to each other, the power storage elements other than the power storage elements having the side electrodes that are either the highest voltage or the lowest voltage among the plurality of power storage elements are excluded. A bus bar that is welded and connected to the side electrode of the power storage element, and a part of which is welded to the end face electrode of the adjacent power storage element;
A lower case having a holding hole into which the bottom of the electricity storage element is inserted;
The upper part of the electricity storage element is inserted, and the upper case is provided with a contact portion with a part of the periphery of the end face having the end face electrode,
Provided only on the bottom surface side of the holding hole of the lower case is an elastic part in contact with the bottom of the electricity storage element,
A power storage unit in which a displacement width of the elastic portion is larger than a height error of the plurality of power storage elements. The power storage unit according to claim 1, wherein the elastic portion is integrally formed with the lower case. The power storage unit according to claim 1, wherein the side electrode, the end surface electrode, and the bus bar are made of the same metal. 2. The power storage unit according to claim 1, wherein the bus bar and the side surface electrode, and the bus bar and the end surface electrode are respectively connected in a linear shape by laser welding. The power storage unit according to claim 1, wherein the adjacent power storage elements have a gap when inserted into the upper case and the lower case. The power storage unit according to claim 1, wherein a bent portion is provided between a portion connected to the end face electrode and a portion connected to the side electrode in the bus bar. 2. The power storage unit according to claim 1, wherein the upper case and the lower case are connected and fixed by tightening fixing screws to fixing rods having female screws formed at both ends through fixing screw holes provided in the upper case and the lower case, respectively.

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