JP5018204B2 - 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, a large-capacity capacitor (for example, an electric double layer capacitor) is required to store electric power that can accelerate the vehicle rapidly. Further, since the charging voltage of this capacitor is as low as about 2.2 V, many capacitors are connected. To increase the voltage.

  A configuration example in which such a large number of power storage elements are held and connected is described in Patent Document 1 below. This is an example of a power storage unit using a cylindrical battery as a power storage element, but as shown in FIG. 8, 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 2 in FIG. 8, the battery hole 2a can be fixed by the peripheral portions of both ends of the cylindrical battery 1 coming into contact 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.

Further, when a power storage unit using a capacitor instead of the cylindrical battery 1 is applied to a hybrid vehicle, charging and discharging of the capacitor during rapid acceleration and regeneration is repeated many times within a short time, and the internal resistance of the capacitor Heat is generated due to the connection resistance with the bus bar. If this is left as it is, the capacitor will deteriorate and its life will be shortened and the reliability will be reduced. However, according to the configuration of FIG. 8, the capacitor is held by the upper and lower supports 2, so In addition, the electrodes at both ends of the capacitor are also exposed through the electrode holes 2b. Therefore, since the generated heat is dissipated from the exposed portion without being trapped, a highly reliable power storage unit that can reduce deterioration of the capacitor can be obtained.
Japanese Patent No. 3777748

  Such a power storage unit can surely hold a large number of power storage elements and at the same time provide good heat dissipation. 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, the bottomed cylinder and the electrode lid are overlapped via an insulating member, and these members are caulked at the same time. In addition to the dimensional error of each member, the caulking process Since an error 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 such a large height error are inserted and held in the support 2 shown in FIG. 8, the step of the battery hole 2a is fixed. The interval is determined by the cylindrical battery 1 having the highest height. 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 strength of the connection part will be weakened and the contact resistance will increase, or mechanical fatigue due to fluctuating stress of the connection plate may occur. As a result, there is a problem that reliability is lowered.

  The present invention solves the above-described conventional problems, and provides a power storage unit that can secure high heat dissipation and can reliably hold a large number of power storage elements having a height error, and can obtain high reliability. Objective.

In order to solve the conventional problems, a power storage unit of the present invention is a columnar shape, each side surface electrodes on the side surfaces and end surfaces, have a edge electrode, a plurality of aligned perpendicularly to the height direction an electric storage device, a bus bar side electrodes and the end electrode each other of the storage element adjacent to the series connection, the with the bottom of the power storage element has a holding hole which are respectively inserted, the end surface of the bottom portion abutting the plurality of resilient portions Are formed on the bottom surface of the holding hole, and an upper case into which the upper part of the power storage element is inserted and at least a part of the end face of the upper part abuts , and each end face of the plurality of power storage elements electrodes are provided in the same direction, at the bottom of the elastic portion is the holding hole is formed in a cantilever shape toward the central upward from the wall surface side of the holding hole, adjacent the elastic During, and a central portion of the bottom surface of the holding hole and the through-hole, 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 plurality of elastic portions have a cantilever shape extending from the wall surface side of the holding hole toward the center upper side, the elastic portion is located at the bottom of the energy storage device when the energy storage device is inserted into the lower case. It abuts and is pressed down. As a result, the elastic part absorbs the height error of the storage element when assembled, so that even if there is a height error, all the storage elements are securely held and fixed, and the connection part between the electrode and bus bar due to vibration or the bus bar itself Can be reduced. Furthermore, between the adjacent elastic parts and the central part of the bottom surface of the holding hole is a through hole, the bottom part of the power storage element is exposed and good heat dissipation can be ensured. From these things, the electrical storage unit which can obtain high reliability is realizable.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In addition, the structural example of the electrical storage unit for vehicles is demonstrated here.

(Embodiment 1)
FIG. 1 is a partially exploded perspective view of a power storage unit according to Embodiment 1 of the present invention. FIG. 2 is a perspective view of a power storage element and a bus bar of the power storage unit according to Embodiment 1 of the present invention. FIG. 3 is a plan view of the lower case of the power storage unit according to Embodiment 1 of the present invention. FIG. 4 is a completed perspective view of the power storage unit according to Embodiment 1 of the present invention. 5A and 5B are cross-sectional views of the power storage unit according to Embodiment 1 of the present invention, where FIG. 5A is a partial cross-sectional view when the power storage element is inserted into the lower case, and FIG. 5B is a cross-sectional view after completion. . 6 is a partial cross-sectional view of another configuration of the power storage unit according to Embodiment 1 of the present invention. FIG. 6 (a) is a partial cross-sectional view when the power storage element is inserted into the lower case, and FIG. A partial cross-sectional view is shown.

  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 22 that fits into the side surface of the power storage element 11 and a flat portion 23 that is welded to the end surface electrode 17 of the adjacent power storage device 11. It is obtained integrally by press molding a 0.5 mm aluminum plate. The bus bar 21 may have a bent portion (not shown) between the portion connected to the end face electrode 17 (flat portion 23) and the portion connected to the side electrode 15 (circumferential portion 22). . As a result, stress applied during welding or vehicle vibration applied to the bus bar 21 or displacement due to thermal expansion can be absorbed by the bent portion, so that reliability is further improved. In addition, it is easier to process the bent portion in the flat portion 23.

  The bus bar 21 is fitted into the side surface of the power storage unit 11 in the direction shown in FIG. 2 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.

  The bus bar 21 is connected to other power storage elements 11 excluding 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 first 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 face electrode 17 is a positive electrode. Are 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. At this time, 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.

  The lower case 31 is made of resin, and a plurality of elastic portions 35 are integrally formed on the bottom surface of the holding hole 33. The shape of the elastic portion 35 is a cantilever shape from the wall surface side of the holding hole 33 toward the upper center on the bottom surface of the holding hole 33. In the first embodiment, eight fan-shaped cantilevers are formed as the elastic portion 35 as shown in FIG. Further, a through hole 36 is formed between the adjacent elastic portions 35 and the central portion of the bottom surface of the holding hole 33. The shape of the through hole 36 is shown in FIG. FIG. 3 is a plan view of the lower case 31 as viewed from above. The through hole 36 has a shape in which a circular hole provided in the center portion of the bottom surface of the holding hole 33 and eight radial holes centered on the circular hole are continuous. In addition, the wall surface side tip of the holding hole 33 in the radial hole is provided with a radius as shown in FIG. This is to reduce stress concentration on the wall surface side of the elastic portion 35. Moreover, since the hole provided in the center part of the bottom face of the holding hole 33 is circular, the tip of the elastic portion 35 has an arc shape. However, this is not limited to the arc shape, and may be a linear shape, for example. .

  As described above, since the elastic portion 35 has a cantilever shape extending from the wall surface side of the holding hole 33 toward the upper center, the tip thereof is positioned higher than the bottom surface of the holding hole 33. Therefore, when the bottom portion 29 of the power storage element 11 contacts the elastic portion 35, the tip of the elastic portion 35 is pushed downward in FIG. At this time, the height from the bottom surface of the holding hole 33 at the tip of the elastic portion 35, that is, the displacement width of the elastic portion 35 is set to be larger than the height error of the plurality of power storage elements 11 obtained in advance. Even if the power storage element 11 having any height error is inserted into the holding hole 33, the elastic portion 35 is displaced and absorbs the error, so that the power storage element 11 can be reliably held.

  Further, since the through hole 36 is provided in the bottom surface of the holding hole 33, the bottom surface of the power storage element 11 is exposed through the through hole 36 even if the power storage element 11 is inserted into the holding hole 33. Therefore, heat dissipation is ensured as in the conventional configuration, and further heat dissipation can be obtained by arranging the power storage unit so as to ventilate the through hole 36.

  In order to obtain good heat dissipation, the area of the through hole 36 at the bottom of the holding hole 33 (here, the area is defined as a projected area when the lower case 31 is viewed from the top as shown in FIG. 3). The same applies hereinafter.) Is larger than the entire area of the elastic portion 35 and the end face of the bottom 29 is exposed as much as possible. However, if the area of the through hole 36 is too large, the following problems occur.

  That is, for example, if the central circular hole in the through hole 36 in FIG. 1 is too large, the length of the elastic portion 35 is shortened. Therefore, when a displacement width equal to or greater than the height error of the power storage element 11 is secured in the elastic portion 35, a large stress is applied to the bottom surface of the power storage element 11 when the power storage element 11 is inserted into the holding hole 33 and the power storage unit is assembled. End up. As a result, depending on the stress, there is a possibility that the elastic part 35 is damaged or the bottom surface of the electricity storage element 11 is deformed.

  On the other hand, if the width of the radial hole in the through hole 36 is too large, the width of the elastic portion 35 becomes narrow and the holding power of the power storage element 11 becomes weak. As a result, there is a possibility that the power storage element 11 cannot be sufficiently held against stress due to vehicle vibration or the like.

  From the above, it is desirable that the through hole 36 is designed to be as large as possible within a range in which the elastic portion 35 can secure a displacement width and a holding force sufficient to hold the power storage element 11. In this case, the number of the elastic portions 35 is eight in the first embodiment, but may be increased or decreased so that the area of the through hole 36 is as large as possible under the above conditions. These designs vary depending on conditions such as the size and weight of the power storage element 11 to be used, further applied vehicle vibrations and necessary heat dissipation characteristics, and may be appropriately designed in consideration of them.

  Here, the description returns to the configuration of FIG. A fixing rod 37 is attached in advance to the lower case 31 in order to firmly fix it to an upper case described later. In the first 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 23 of the bus bar 21 needs to cover the end surface electrode 17 of the adjacent power storage element 11, and as shown in FIG. Are sequentially inserted from the power storage element 11 toward the back. Accordingly, the flat portion 23 of the bus bar 21 connected to the adjacent power storage element 11 contacts the end surface 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 electrode terminal bus bar, which will be described later, is connected here.

  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. In the first embodiment, the abutting portion 47 is configured to abut against a part of the end surface surrounding portion 13, but this may be configured such that the entire end surface surrounding portion 13 abuts. 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 first 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 23 of the bus bar 21 becomes long 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. In addition, if the above-mentioned bending part is provided in the bus-bar 21, the influence of pressing by the bus-bar 21 of the other electrical storage element 11 etc. can be absorbed further.

  Here, a cross-sectional view of a portion indicated by a dotted line in FIG. 4 is shown in FIGS. FIG. 5A is a partial cross-sectional view showing a state in which the bottom 29 of the electricity storage device 11 is inserted in the holding hole 33 in the direction of the arrow with the fixing rod 37 attached to the lower case 31 in advance. FIG. 5B is a cross-sectional view when the power storage unit 61 is completed. 5A and 5B, the clearance due to the difference in diameter between the storage element 11 and the holding hole 33 is omitted.

  As described above, since the elastic portion 35 has a cantilever shape extending from the wall surface side of the holding hole 33 toward the upper center, the tip of the elastic portion 35 in FIG. 5A is lifted upward. After the storage element 11 has been inserted into the holding hole 33, the upper portion 45 of the storage element 11 is inserted into the upper case 43 while the end face of the bottom 29 is in contact with the tip of the elastic portion 35, and the upper case 43 is fixed to the fixing screw 41. Then, as shown in FIG. 5B, a part of the end surface peripheral portion 13 of the power storage device 11 is pushed down by the contact portion 47. However, since the fixing screw 41 is a flat head screw, it is not shown in FIG. With this configuration, the bottom 29 of the electricity storage element 11 is fixed by pushing down the elastic portion 35. The displacement width of the elastic part 35 at this time is larger than the height error of the electricity storage element 11 as indicated by an arrow in FIG. Even if there is an error in height, 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. In addition, since the through hole 36 is provided between the elastic portions 35 and the central portion of the bottom surface of the holding hole 33, for example, by arranging the power storage unit 61 so as to ventilate the bottom surface of the lower case 31, The heat generated in the electricity storage element 11 is dissipated through. Therefore, good heat dissipation can be secured and high reliability can be obtained.

  With the above configuration, heat dissipation by the through hole 36 and absorption by the elastic portion 35 of the height error of the power storage element 11 are reduced, so heat generation of the power storage element 11 and fluctuating stress fatigue of the bus bar 21 are reduced, and high reliability. We were able to realize a power storage unit with

  In the configuration of FIGS. 1 to 5, since the power storage element 11 has the side electrode 15, there is no need to attach the bus bar 21 to the bottom surface of the power storage element 11. When the electrodes are provided only at both ends, the bus bar 21 needs to be connected to the bottom surface of the power storage element 11. 6A and 6B are partial sectional views of the power storage unit 61 in this case. 6A is a partial cross-sectional view showing a state in which the bottom 29 of the power storage element 11 is inserted in the holding hole 33 in the direction of the arrow with the fixing rod 37 attached to the lower case 31 in advance. . FIG. 6B is a partial cross-sectional view after the storage element 11 is inserted. 6A and 6B, the clearance due to the difference in diameter between the storage element 11 and the holding hole 33 is omitted.

  The bus bar 21 is connected to the bottom surface of the bottom portion 29 of the power storage element 11 and has a structure that is pulled out to connect to another power storage element 11. Therefore, as shown to Fig.6 (a), the cross section of the bus-bar 21 in the bottom part 29 becomes L shape. In this state, when the bottom portion 29 is inserted into the holding hole 33 in the direction of the arrow, the tip of the elastic portion 35 comes into contact with the bottom surface of the bottom portion 29 and is pushed down, but the bus bar 21 is connected to the bottom surface. The bottom surface is not a plane as shown in FIG. In this case, as shown by the thick dotted line in FIG. 6B, the elastic portions 35 (two on the right side) where the bus bar 21 is connected are replaced with the elastic portions 35 (two on the left side) where the bus bar 21 is not connected. Compared with the thickness of the bus bar 21, the displacement is greatly increased. Accordingly, the elastic portion 35 absorbs not only the height error of the power storage element 11 but also the non-uniformity of the bottom surface due to the thickness of the bus bar 21, so that the bus bar 21 is connected to the bottom surface. All the power storage elements 11 can be reliably fixed, and high reliability can be obtained. In order to cope with any non-uniformity of the bottom surface, it is desirable that the number of elastic portions 35 is large.

  In the first 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 placed at a position facing the screw hole 27 of the upper case 43. It is good also as a structure which provides by integral 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.

(Embodiment 2)
7A and 7B are partial cross-sectional views illustrating a method for assembling the power storage unit according to Embodiment 2 of the present invention, in which FIG. 7A is a partial cross-sectional view when the power storage element is inserted into the lower case, and FIG. (C) is a partial cross-sectional view when the power storage unit is removed from the assembly table, and (d) is a partial cross-sectional view after applying the insulating high thermal conductive grease to the back surface of the lower case. Sectional view, (e) shows a partial cross-sectional view after application of insulating high thermal conductive grease to the back surface of the lower case, and (f) shows a partial cross-sectional view after attachment to the base of the power storage unit. 7A to 7F, the clearance due to the difference in diameter between the electric storage element 11 and the holding hole 33 is exaggerated from the actual one for the sake of clarity.

  In the components of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. That is, the feature of the second embodiment is that when a power storage device is configured by arranging a plurality of power storage units 61, heat dissipation can be ensured even if they are arranged so as not to ventilate the bottom surface of the lower case 31. In order to realize this, in the second embodiment, the following configuration is added to the configuration of the first embodiment.

  1) A configuration in which a plurality of power storage units 61 are arranged by fixing the lower case 31 to a metal base 71.

  2) Insulating high thermal conductive grease 73 was disposed between the bottom 29 of the energy storage device 11 and the pedestal 71 and between the lower case 31 and the pedestal 71.

  3) A step 74 is provided at a part of the lower case 31 facing the pedestal 71.

  In the second embodiment, the metal pedestal 71 is made of aluminum with good thermal conductivity and light weight. The insulating high thermal conductive grease 73 has a structure in which a ceramic (alumina) filler is mixed with a silicon resin, for example. Further, the step 74 is formed integrally with the lower case 31 and its height is set to about 0.2 mm from the lower case 31 to the pedestal 71 in order to obtain as good heat dissipation as possible. By providing the step 74 in this way, the thickness of the insulating high thermal conductive grease 73 disposed in the portion where the lower case 31 and the pedestal 71 face each other becomes equal to the height of the step 74 (0.2 mm). As a result, when the plurality of power storage units 61 are arranged on the pedestal 71, the thickness of the insulating high thermal conductive grease 73 between the lower case 31 and the pedestal 71 becomes equal, so that variation in heat dissipation between the power storage units 61 can be reduced. .

  Next, an assembly method for realizing the above configuration will be described with reference to FIG.

  First, as shown in FIG. 7A, the lower case 31 to which the fixing rod 37 is fixed in advance is attached to the assembly table 75. Although not shown, the attachment is performed by tightening the screw into the assembly base 75 through the screw hole of the fixing portion formed integrally with the lower case 31.

  Next, insulating high thermal conductive grease 73 is injected into the bottom surface of the holding hole 33. The injection amount at this time is determined in advance as an amount that can fill the space between the bottom 29 and the base 71 after the power storage unit 61 is attached to the base 71. In the second embodiment, the elastic portion 35 is buried in the insulating high heat conductive grease 73 by the injection of a predetermined amount of the insulating high heat conductive grease 73 as shown by the dotted line in FIG. Accordingly, the through hole 36 is filled with the insulating high thermal conductive grease 73. A dispenser was used to inject the insulating high thermal conductive grease 73 by the determined amount.

  Next, the bottom portion 29 of the electric storage element 11 is inserted into the holding hole 33 in the direction of the arrow. Although not shown, the upper case 43 is fixed to the fixing rod 37 as in the first embodiment, and the bus bar 21 is welded. Thus, the assembly of the power storage unit 61 is completed. A cross-sectional view of the vicinity of the lower case 31 at this time is shown in FIG. By inserting the bottom portion 29 into the holding hole 33, the bottom surface of the bottom portion 29 comes into contact with the tip of the elastic portion 35, and the elastic portion 35 is pushed down. As a result, similar to the first embodiment, the height error of the power storage element 11 can be absorbed, and reliable holding can be achieved.

  In addition, the space surrounded by the bottom surface of the bottom portion 29, the wall surface of the holding hole 33, and the assembly table 75 is filled with the insulating high heat conductive grease 73. At the same time, by inserting the bottom 29 into the holding hole 33, the insulating high thermal conductive grease 73 rises through the gap (clearance portion) between the two, and fills the gap. As a result, the gap between the bottom 29 and the holding hole 33, that is, the space and the clearance portion, is entirely filled with the insulating high thermal conductive grease 73. At this time, since the power storage element 11 is inserted into the holding hole 33 while compressing the insulating high heat conductive grease 73 at the bottom 29, the insulating high heat conductive grease 73 can be disposed without generating bubbles that deteriorate the heat conduction. . Further, a part of the insulating high thermal conductive grease 73 also extends to the gap between the lower case 31 and the assembly table 75 formed by the step 74.

  Next, as shown in FIG. 7C, the power storage unit 61 is removed from the assembly table 75. Specifically, the power storage unit 61 is lifted after removing a screw (not shown) to which both are attached. By this step, the insulating high thermal conductive grease 73 adheres to both the lower case 31 side and the assembly base 75 side, and the surface thereof becomes uneven as shown in FIG.

  Therefore, in order to smooth the unevenness and simultaneously apply insulating high heat conductive grease 73 corresponding to the height of the step 74 on the bottom surface of the lower case 31, the removed power storage unit 61 is turned upside down. The state at this time is shown in FIG. Here, by using the squeegee 77 and moving it in the direction of the arrow, the insulating high thermal conductive grease 73 is applied to the bottom surface of the lower case 31 other than the step 74. At this time, since the fixing screw 41 is a flat head screw as described in the first embodiment, the head of the fixing screw 41 does not protrude from the lower case 31. Therefore, as shown in FIG. 7E, the insulating high thermal conductive grease 73 can be smoothly and smoothly applied to the entire bottom surface (except for the step 74) of the lower case 31 by the squeegee 77 at a time. At this time, even if it has open pores (open bubbles), by applying the insulating high thermal conductive grease 73 again with the squeegee 77, there can be no open pores.

  After that, as shown in FIG. 7 (f), the power storage unit 61 is turned upside down and returned to its original position, and in that state, fixed to the pedestal 71 with screws (not shown), thereby completing the mounting of the power storage unit 61. .

  By such an assembling method, bubbles are generated in the space surrounded by the bottom surface of the bottom portion 29, the wall surface of the holding hole 33 and the pedestal 71, the clearance portion between the holding hole 33 and the bottom portion 29, and between the lower case 31 and the pedestal 71. The insulating high thermal conductivity grease 73 can be disposed in a uniform amount without any problem, so that the heat of the power storage element 11 can be efficiently transferred to the pedestal 71 without variation as shown by the arrow in FIG. Is possible.

  With the above configuration, the bottom portion 29 of the power storage element 11 is thermally coupled to the base 71 via the insulating high thermal conductive grease 73, so that heat can be efficiently dissipated even in a configuration in which ventilation to the bottom surface of the lower case 31 is not possible. In addition, since the power storage element 11 having a height error can be securely held, a highly reliable power storage unit can be realized.

  In addition, in order to further improve the heat dissipation, the pedestal 71 may be provided with fins on the back side of the surface to which the power storage unit 61 is fixed, or may be provided with a water channel through which cooling water flows inside or outside the pedestal 71. .

  In the second embodiment, when assembling the power storage unit 61, the assembly unit 75 is once assembled and then attached to the base 71. To simplify the process, the base 71 is used from the beginning without using the assembly base 75. A method of fixing and assembling the lower case 31 is also conceivable. However, in this case, there is no step of removing the lower case 31 from the assembly table 75 as shown in FIG. 7C, and therefore whether or not the insulating high thermal conductive grease 73 is reliably filled also on the back surface of the elastic portion 35 is determined. In addition, if it is not filled and has bubbles, it cannot be filled with the insulating high thermal conductive grease 73 later. Furthermore, in the case of a power storage device using a large number of power storage units 61, the pedestal 71 has a large area and the assembling workability becomes extremely poor. For these reasons, a process using the assembly table 75 is desirable.

  Further, in the second embodiment, the step 74 is integrally provided in the lower case 31, but instead of the step 74, for example, a thickness of 0.2 mm is provided at a part between the lower case 31 and the base 71. The spacer may be interposed. As a material for the spacer, a material having a high thermal conductivity (for example, metal or carbon) equal to or higher than that of the lower case 31 may be used. Thereby, compared with the case where the level | step difference 74 is provided, although the number of components increases, the improvement of the further heat dissipation from the lower case 31 to the base 71 can be aimed at.

  Moreover, although Embodiment 1 and 2 demonstrated that the electrical storage element 11 was cylindrical, this may be 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.

  Further, the power storage unit 61 described in the first and second embodiments is not limited to an auxiliary power source for a vehicle, and can be applied to a general emergency auxiliary power source.

  The power storage unit according to the present invention has high reliability due to the high heat dissipation due to the through-holes and the reduced stress fatigue of the bus bar due to the configuration in which the elastic portion absorbs the height error of the power storage element. This is useful as a power storage unit for a vehicle which is severe and receives vibration.

The partial exploded perspective view of the electrical storage unit in Embodiment 1 of this invention The perspective view of the electrical storage element and bus bar of the electrical storage unit in Embodiment 1 of this invention Plan view of lower case of power storage unit in Embodiment 1 of the present invention Completion perspective view of power storage unit in Embodiment 1 of the present invention It is sectional drawing of the electrical storage unit in Embodiment 1 of this invention, (a) Partial sectional view at the time of insertion of the electrical storage element to a lower case, (b) Sectional drawing after completion It is a partial cross section figure of other composition of the electrical storage unit in Embodiment 1 of the present invention, (a) Partial sectional view at the time of insertion of an electrical storage element to a lower case, (b) Partial sectional view after insertion It is a partial cross section figure which shows the assembly method of the electrical storage unit in Embodiment 2 of this invention, (a) Partial sectional view at the time of insertion of the electrical storage element to a lower case, (b) One after completion of an electrical storage unit Partial sectional view, (c) Partial sectional view when removing the power storage unit from the assembly table, (d) Partial sectional view when applying the insulating high thermal conductive grease to the lower case back surface, (e) To the lower case rear surface Partial cross-sectional view after application of insulating high thermal conductive grease, (f) Partial cross-sectional view after attachment of power storage unit to pedestal A perspective view of a conventional power storage unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Power storage element 21 Bus bar 29 Bottom part 31 Lower case 33 Holding hole 35 Elastic part 36 Through hole 43 Upper case 45 Upper part 47 Contact part 71 Base 73 Insulating high heat conduction grease 74 Step

Claims (7)

The plurality of power storage elements that are pillar-shaped , have side-surface electrodes and end-surface electrodes on side surfaces and end surfaces, respectively, and are arranged in a direction perpendicular to the height direction ;
A bus bar for connecting side electrodes and end electrodes of the power storage elements adjacent to each other in series ;
A lower case provided with a plurality of elastic parts on the bottom surface of the holding hole, each having a holding hole into which the bottom part of the electricity storage element is inserted, and an end surface of the bottom part;
The upper part of the power storage element is inserted, and is configured from an upper case with which at least a part of the end face of the upper part comes into contact,
Each end face electrode of the plurality of power storage elements is provided in the same direction,
The elastic part is formed in a cantilever shape from the wall surface side of the holding hole toward the upper center on the bottom surface of the holding hole,
Between the adjacent elastic parts and the central part of the bottom surface of the holding hole as a through hole,
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 an area of the through hole is larger than a total area of the elastic portion at a bottom portion of the holding hole. The power storage unit according to claim 1, wherein the lower case is fixed to a metal pedestal, and insulating high thermal conductive grease is disposed between the bottom and the pedestal, and between the lower case and the pedestal. The power storage unit according to claim 3, wherein the insulating high thermal conductive grease has a configuration in which a ceramic filler is mixed with a resin. The power storage unit according to claim 3, wherein a step is provided in a part of a portion of the lower case facing the pedestal. The power storage unit according to claim 3, wherein a spacer is interposed in a part between the lower case and the pedestal. The power storage unit according to claim 6, wherein the spacer is made of a material having a high thermal conductivity equal to or higher than that of the lower case.

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