Storage battery and battery case molds

Abstract

To easily eliminate defective molding of a battery case.SOLUTION: At the time of injection molding, in a container 1 manufactured by supplying a molten resin from the position corresponding to the lower part of the container 1, a plurality of ribs 21 and 22 extending in the vertical direction are provided on at least a second wall 12, which is the inner wall of the container, and the central rib 21 in the left and right direction is formed with a large width longer in the vertical direction than the remaining ribs 22, and also in the horizontal direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a storage battery having a battery case and a mold for the battery case. [Background technology]

[0002] Some storage batteries, such as lead-acid batteries, use a battery case whose interior space is divided into multiple cell chambers by partition walls. This type of battery case is manufactured, for example, by using an injection molding machine to inject molten resin into a mold of a predetermined shape and then solidifying it. A known structure of conventional battery cases is one in which the strength of the central portion is increased by providing multiple ribs extending in the vertical direction on the inner wall of the battery case facing the partition wall and on the partition wall, with the central ribs on the left and right sides being longer than the other ribs (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4374656 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the reasons for molding defects during injection molding is that the resin hardens before reaching every corner of the mold. For example, if the resin is supplied from a position corresponding to the bottom of the battery case, the resin may not reach the center of the left and right sides of the inner wall or partition wall of the battery case, resulting in molding defects. According to the inventors' research, when the central rib among multiple ribs is lengthened, as exemplified in Patent Document 1, although the groove in the mold corresponding to the central rib can guide the resin to the center of the left and right sides of the wall, this is still insufficient to eliminate molding defects.

[0005] Therefore, an object of the present invention is to easily eliminate molding defects in battery cases. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the internal space is divided into multiple cell chambers by partition walls. Ta Equipped with a battery case ,before At the bottom of the electrostat There are gate marks from injection molding In the storage battery, the battery case is at least The inner wall of the battery case facing the partition wall To, The seat belt has a plurality of ribs extending in the vertical direction, and the rib at the center of the plurality of ribs in the left and right directions is longer in the vertical direction and wider in the left and right direction than the remaining ribs.

[0007] In the above configuration, the plurality of ribs may have the same amount of protrusion from the inner wall of the battery case and / or the wall made of the partition wall on which the ribs are provided.

[0008] In the above configuration, of the multiple ribs, the ribs other than the left and right central rib are provided in equal numbers at positions symmetrical to the left and right with respect to the left and right central rib, and have the same shape including width, vertical length, lower end position and upper end position, and the left and right spacing of all the ribs including the left and right central rib may be the same.

[0009] In addition, in a mold for a battery case for manufacturing, by injection molding, a battery case whose internal space is divided into a plurality of cell chambers by partition walls, the mold for the battery case has a gate for injecting molten resin at a position corresponding to the lower part of the battery case, and has an internal space connected to the gate and corresponding to the battery case, and the internal space is at least The inner wall of the battery case facing the partition wall to The present invention is characterized in that it includes a space in which a plurality of ribs extending in the vertical direction are provided, and the rib at the center in the left and right directions among the plurality of ribs is longer in the vertical direction and wider in the left and right direction than the remaining ribs. [Effects of the Invention]

[0010] According to the present invention, molding defects caused by insufficient filling of the wall of the battery case can be easily eliminated. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a top view of a battery case of a lead-acid battery according to an embodiment of the storage battery of the present invention. FIG. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] FIG. 3 is a view taken along arrow B in FIG. 2. [Figure 4] 1A to 1C are diagrams schematically illustrating injection molding of a battery case according to a first reference example. [Figure 5] 10A to 10C are diagrams illustrating the injection molding of a battery case according to a second reference example. [Figure 6] 1A to 1C are diagrams schematically illustrating injection molding of a battery case according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a top view of a battery case for a lead-acid battery according to an embodiment of the storage battery of the present invention. The lead-acid battery includes a battery case 1 and a plate group 3 housed in the battery case 1. The battery case 1 has an internal space divided into multiple cell chambers 4 by multiple partition walls 13, and its upper opening is covered with a lid (not shown). The battery case 1 integrally includes a pair of first walls 11 erected on a pair of long sides of a rectangular bottom plate 19 (see FIG. 2, etc.), second walls 12 erected on a pair of short sides, and multiple partition walls 13 bridging the first walls 11. The partition walls 13 are parallel to the second walls 12 and are arranged at equal intervals. In this embodiment, five partition walls 13 are provided to divide the battery case into six cell chambers 4. However, the number of partition walls 13 may be changed as appropriate. Furthermore, the partition walls 13 do not have to be parallel to the second walls 12.

[0013] This battery case 1 is manufactured by using an injection molding machine to heat and melt pellets to obtain a thermoplastic resin, which is then fed into a mold 31 (FIG. 6) and then cooled and solidified. The material of the battery case 1 is, for example, PE (polyethylene) or PP (polypropylene). The second wall 12 corresponds to the "inner wall of the battery case opposite the partition wall 13" in this invention.

[0014] 1, the arrangement direction of the cell chambers 4 is the X direction, and the horizontal direction perpendicular to the X direction is the Y direction. In each cell chamber 4, a plate group 3 that constitutes a cell battery is arranged. The electrode plate group 3 has a structure in which multiple negative and positive electrode plates are alternately stacked with separators interposed between them, with the lugs of each negative electrode plate connected by a negative electrode strap and the lugs of each positive electrode plate connected by a positive electrode strap. The negative electrode strap and the positive electrode strap are arranged at different positions in the width direction of the negative and positive electrode plates (the direction that corresponds to the Y direction when placed in the cell chamber 4). The electrode plate group 3 further has a negative electrode intermediate pole that protrudes upward from one end of the negative electrode strap in the X direction, and a positive electrode intermediate pole that protrudes upward from the other end of the positive electrode strap in the X direction.

[0015] FIG. 2 corresponds to a cross-sectional view taken along line AA in FIG. 1, and shows a part of a side cross section of the battery case 1. As shown in FIG. 3 corresponds to a view seen from the arrow B in FIG. 2, and shows a part of the second wall 12. FIG. As shown in FIG. 2, each partition wall 13 stands vertically, and each second wall 12 facing the partition wall 13 is integrally provided with a plurality of ribs 21, 22 extending in the vertical direction. It should be noted that ribs having the same shape as the ribs 21 and 22 provided on the second wall 12 may be provided on the partition wall 13.

[0016] The rib 21 is a rib provided at the left-right center (corresponding to the center in the Y direction) of the second wall 12. The ribs 22 are provided on the left and right of the left-right center rib 21. The left and right ribs 22 are a plurality of ribs provided in equal numbers at positions symmetrical to the left and right with respect to the left-right center rib 21. These ribs 22 differ from the left-right center rib 21 in their vertical length (length L2 shown in FIG. 3) and left-right length (width W2 shown in FIG. 3).

[0017] The walls 13, 12 and the ribs 21, 22 will now be described in detail. 2, in adjacent walls 13, 12, a separation distance P1 from the ribs 21, 22 of the second wall 12 to the surface of the partition wall 13 is set to a distance corresponding to the thickness of the electrode plate pack 3. The ribs 21, 22 provided on each second wall 12 have the same protrusion amount D1 (also referred to as protrusion height) from the corresponding wall 12. 2, each partition wall 13 is formed as a vertically erected wall, whereas the second wall 12 is formed as a wall having an inclined surface that functions as a so-called draft gradient. For this reason, the ribs 21, 22 provided on the second wall 12 are formed so that the protrusion amount D1 decreases downward so as to keep the separation distance P1 constant across the top and bottom.

[0018] If the second wall 12 is formed as a vertically erected wall, the second wall 12 and the partition wall 13 will be completely parallel, so the protrusion amount D1 of the ribs 21, 22 provided on the second wall 12 can be made the same value across the top and bottom.

[0019] As shown in Figures 2 and 3, the left and right ribs 22 provided on the second wall 12 have the same shape in each part, including the lower end position, upper end position, and protrusion amount D1, and further have the same lower end position as the rib 21. 2 shows an example in which the upper portions of the ribs 21, 22 are formed in an inclined shape in which the protrusion amount D1 gradually decreases as the ribs go upward. This inclined shape makes it easier to smoothly insert the electrode plate group 3 between the cell chambers 4 at both left and right ends, with the separation distance P1. However, this inclined shape is not necessarily required. At least one of the cell chambers 4 at both the left and right ends is often located in the engine compartment, close to a heat source such as an engine. It is generally known that lead-acid batteries deteriorate more rapidly at higher operating temperatures. Furthermore, the greater the contact area between the electrode plates and the electrolyte, the more rapidly the battery deteriorates. Therefore, worn electrode plates deteriorate more rapidly. When inserting the electrode plate group 3 into the cell chamber 4, if a large force is applied to the electrode plate group 3 due to factors such as a small separation distance P1, the protrusions such as the ribs 21 and 22 may cause wear on the electrode plate surfaces. Forming the inclined shape shown in Figure 2 can suppress such wear and is expected to extend the life of the lead-acid battery.

[0020] As shown in Fig. 3, only one rib 21 is provided in the left-right center, and is longer in the up-down direction and wider in the left-right direction (corresponding to the Y direction) than the ribs 22 located on either side of this rib 21. The left and right ribs 22 are arranged at equal intervals on the left and right. In the following explanation, when the ribs 21 and 22 are to be particularly distinguished from each other, they will be referred to as the first rib 21 and the second rib 22, respectively.

[0021] In Fig. 3, the height of the second wall 12 (which is the same as the height of the partition wall 13 and the height of the battery case 1) is indicated by the symbol L0, the length of the first rib 21 (also referred to as rib length) is indicated by the symbol L1, and the length of the second rib 22 (also referred to as rib length) is indicated by the symbol L2. The width of the first rib 21 is indicated by the symbol W1, and the width of the second rib 22 is indicated by the symbol W2. The height L0 of the second wall 12 > the length L1 of the first rib 21 > the length L2 of the second rib 22. The symbol LC in Fig. 3 indicates the left-right center of the second wall 12 (which is the same as the left-right center of the partition wall 13).

[0022] The second ribs 22 are provided at positions where they contact the electrode plates located at one end of the electrode plate pack 3. Each of the second ribs 22 extends linearly upward from the bottom plate 19, and its upper end is set at a position spaced a predetermined value Z2 from the upper end of the second wall 12. For example, the upper end of the second rib 22 is set at a position where the second rib 22 can contact both the top and bottom of the electrode plate located at one end of the electrode plate pack 3. For example, the value Z2 is set in the range of 25% to 35% of the height L0 of the second wall 12; in other words, the length L2 of the second rib 22 is set in the range of 65% to 75% of the height L0 of the second wall 12.

[0023] The width W2 of the second ribs 22 and the spacing (also referred to as pitch) between the second ribs 22 are set to values ​​that ensure a sufficient contact area with the electrode plate pack 3 while ensuring gaps between the second ribs 22 and between the second ribs 22 and the first rib 21 that allow sufficient passage of air and reactive gases. This allows the second ribs 22 to suppress changes in the distance between the electrode plates of the electrode plate pack 3 and makes it easier to suppress temperature increases in the electrode plate pack 3. For example, the width W2 of the second rib 22 is preferably 2.0 mm or more and 5.0 mm or less, and in the range of 40 to 80% of the width W1 of the first rib 21, and the spacing between the second ribs 22 is preferably in the range of 8 to 30% of the left-right width of the second wall 12.

[0024] The first rib 21 extends linearly upward from the bottom plate 19 and extends to the vicinity of the upper end of the second wall 12, thereby extending higher than the second rib 22. In this embodiment, the upper end of the first rib 21 is set at a position spaced a predetermined distance Z1 from the upper end position of the second wall 12. The value Z1 is smaller than the value Z2. For example, the value Z1 is preferably in the range of 3 to 20% of the height L0 of the second wall 12. In other words, the length L1 of the first rib 21 is preferably in the range of 80 to 97% of the height L0 of the second wall 12. The first rib 21 can suppress expansion of the left-right center of the electrode plate pack 3 in the cell chamber 4, which is disposed on the outermost side and is likely to be closest to the heat source in the engine compartment. The width W1 of the first rib 21 is larger than the width W2 of the second rib 22, so expansion of the left-right center of the electrode plate pack 3 can be more effectively suppressed. These ribs 21, 22 also function as reinforcing ribs that reinforce the second wall 12.

[0025] Here, if the width W1 and rib length L1 of the first rib 21 are made larger than those of the second rib 22, when manufacturing the battery case 1 by injection molding, it becomes easier to flow molten resin into the space corresponding to the left-right center of the second wall 12 in a mold 31 (Figure 6) having an internal space corresponding to the battery case 1.Therefore, by setting the width W1 and length L1 of the first rib 21 so that the resin reaches the left-right center of the second wall 12, it becomes easier to eliminate molding defects in the battery case 1. Furthermore, from the viewpoint of obtaining the strength to suppress expansion of the left and right central portions of the electrode plate group 3 and from the viewpoint of reinforcing the second wall 12, it is effective to increase the width W1 and the length L1 of the first rib 21.

[0026] FIG. 4 is a diagram schematically showing injection molding of a battery case 1A according to a first reference example. In FIG. 4, reference numeral 31A denotes a mold having an internal space corresponding to the battery case 1A (the female mold forming the internal space is also called a cavity, and the corresponding male mold is also called a core). The battery case 1A according to the first reference example differs from the battery case 1 of this embodiment in that the length L1 and width W1 of the first rib 21 are the same as the length L2 and width W2 of the second rib 22. In injection molding, a gate G for injecting thermoplastic resin (hereinafter referred to as molten resin SM) into the mold 31A is provided at a position corresponding to the lower part of the battery case 1A. The location of the gate G is not limited to one position corresponding to the lower part of the battery case 1A, but may be two or more positions corresponding to the lower part of the battery case 1A. 4, the symbol SP schematically indicates the internal space of the mold 31A, which is also the internal space that forms the battery case 1A. In this internal space SP, locations corresponding to the various parts of the battery case 1A (ribs 21, 22, second wall 12, first wall 11, and bottom plate 19) are indicated by the symbols of the various parts.

[0027] As shown in Figure 4, the molten resin SM flowing in from the gate G is supplied into the mold 31A from the space corresponding to the bottom plate 19 of the battery case 1A, through the grooves corresponding to the ribs 21 and 22, the space corresponding to the second wall 12, and the space corresponding to the first wall 11. In the first reference example, although a portion of the molten resin SM can be guided to the space corresponding to the upper end of the second wall 12 by the grooves corresponding to the ribs 21, 22, as shown in Fig. 4, the amount of resin supplied to the space corresponding to the left-right center of the second wall 12 may be relatively smaller than the amount of resin supplied to the spaces corresponding to both left and right sides of the second wall 12. For this reason, the molten resin SM may solidify before reaching the left-right center of the second wall 12, which may result in molding defects as shown in the bottom row of Fig. 4.

[0028] FIG. 5 is a diagram schematically showing injection molding of a battery case 1B according to a second reference example. In FIG. 5, reference numeral 31B denotes a mold having an internal space SP corresponding to the battery container 1B. The battery case 1B according to the second reference example differs from the battery case 1 of this embodiment in that the width W1 of the first rib 21 is the same as the width W2 of the second rib 22. In the second reference example, the first rib 21 at the left and right center is longer than the second ribs 22 at the left and right, so that, compared to the second reference example, more of the molten resin SM can be guided to the space corresponding to the left and right center of the second wall 12 during injection molding. However, as shown in Figure 5, even in the second reference example, the amount of resin supplied to the space corresponding to the center of the second wall 12 is relatively less than the amount of resin supplied to the spaces corresponding to both the left and right sides of the second wall 12, which may result in molding defects such as those shown in the bottom row of Figure 5.

[0029] Here, the degree of insufficiency in the amount of resin supplied to the space corresponding to the center of the second wall 12 is affected by various parameters related to the gate G and the pressure and temperature of the molten resin SM, in addition to parameters related to the shape of the battery container, such as the surface shape and thickness distribution of the second wall 12. According to the inventors' studies, there is a limit to the adjustment range when only adjusting the length of the first rib 21, and it may not be possible to sufficiently suppress molding defects, or it may be necessary to reconsider the above multiple parameters in order to sufficiently suppress molding defects. Furthermore, the lower the height of the second wall 12, or the higher the ratio of the length L2 of the second rib 22 to the height of the second wall 12, the smaller the effect of suppressing molding defects by adjusting the length of the first rib 21. For example, if the height of the second wall 12 is less than 180 mm or the ratio of the length L2 of the second rib 22 to the height of the second wall 12 exceeds 75%, it becomes more difficult to suppress molding defects as described above.

[0030] FIG. 6 is a diagram schematically showing injection molding of the battery case 1 according to this embodiment. In Fig. 6, reference numeral 31 denotes a mold having an internal space SP corresponding to the battery case 1. This mold 31 corresponds to the "battery case mold" in this invention. In this battery case 1, the first rib 21 is longer in the up-down direction and wider in the left-right direction than the second rib 22, so the fluidity of the molten resin SM is improved compared to the first and second reference examples. As a result, as shown in Fig. 6, more of the molten resin SM can be guided to the space corresponding to the left-right center of the second wall 12, and the molten resin SM can be spread throughout the entire space corresponding to the second wall 12, making it easier to prevent molding defects in the second wall 12. If ribs 21, 22 are provided on the partition wall 13 (see FIG. 2), the first rib 21 can be made longer in the up-down direction and wider in the left-right direction than the second rib 22 in the partition wall 13, thereby improving the fluidity of the molten resin SM in the partition wall 13. This allows more of the molten resin SM to be guided to the space corresponding to the center of the left and right of the partition wall 13, allowing the molten resin SM to spread throughout the entire space corresponding to the partition wall 13, making it easier to suppress molding defects in the partition wall 13.

[0031] Furthermore, even if the shape of the battery case 1 is different, by combining the length and width adjustments of the first rib 21 provided on the second wall 12, it becomes easy to eliminate molding defects caused by insufficient filling at the center of the left and right of the second wall 12. Therefore, when the design of the battery case 1 is changed, it becomes easy to eliminate molding defects of the second wall 12 simply by adjusting the length and width of the first rib 21. As a result, it is also expected to have the effect of reducing the labor required to adjust various parameters of the injection molding machine.

[0032] Although the above description has been given of a case in which the length and width of the first rib 21 of each wall 12 are made larger than the second rib 22 so as to eliminate molding defects of each wall 12 only for the second wall 12, the present invention is not limited to this. For example, when manufacturing conditions are such that molding defects are likely to occur in both walls 13, 12, and molding defects can be sufficiently suppressed by adjusting the length and width of the first rib 21 provided on each wall 13, 12, the length and width of the first rib 21 provided on the other of the walls 13, 12 may be adjusted to be larger than the second rib 22.

[0033] As described above, in the battery container 1 manufactured by supplying molten resin SM into a mold having an internal space SP corresponding to the shape of the battery container 1 from a position corresponding to the lower part of the battery container 1, at least the second wall 12 of the walls 13, 12 of the battery container 1 is provided with a plurality of ribs 21, 22 extending in the vertical direction, and the rib 21 at the center of the left and right is formed to be longer in the vertical direction and wider in the horizontal direction than the remaining ribs 22. This improves the fluidity of the molten resin SM in the wall 12, making it easier to eliminate molding defects caused by an insufficient filling amount into the wall 12 during injection molding.

[0034] Furthermore, the ribs 21, 22 are formed so that the amount of protrusion D1 from any of the second walls 12 on which these ribs are provided is the same if the ribs are at the same height in the vertical direction between the ribs. This aligns the protruding surfaces of the ribs 21, 22 provided on the second wall 12 in the same plane, making it easier to evenly press the electrode plate group 3 arranged in the cell chamber 4.

[0035] Furthermore, the ribs 22, excluding the rib 21 at the center of the left and right sides, are provided in equal numbers at symmetrical positions with respect to the rib 21 at the center of the left and right sides, and are formed with the same shape, including the width W2, the length L2 in the vertical direction, and the lower and upper end positions. This makes it easier for the ribs 21, 22 to feed resin evenly to the left and right sides. With this configuration, adjusting the width W1 and length L1 of the rib 21 at the center of the left and right sides to compensate for the insufficient filling amount at the center of the left and right sides makes it easier to eliminate molding defects throughout the second wall 12.

[0036] 6, the mold 31 used to produce the battery case 1 by injection molding has a gate G for introducing molten resin SM at a position corresponding to the lower part of the battery case 1, and has an internal space SP connected to the gate G and corresponding to the battery case 1. The internal space SP includes a space in at least the second wall 12 where a plurality of ribs 21, 22 extending in the vertical direction are provided, and the central rib 21 of the plurality of ribs 21, 22 is formed to be longer in the vertical direction and wider in the horizontal direction than the remaining ribs 22. This improves the fluidity of the molten resin SM in the region corresponding to the second wall 12, making it easier to eliminate molding defects caused by insufficient filling of the second wall during injection molding.

[0037] The present invention is not limited to the above-described embodiment, and various modifications and changes are possible based on the technical concept of the present invention. For example, although the case has been described where the protrusion amounts D1 of the ribs 21, 22 from the second walls 12, 13 are the same, a configuration where these protrusion amounts D1 are not the same may be adopted as long as there is no problem in supporting the electrode plate pack 3. Furthermore, although the case has been described where the ribs 22, excluding the central rib 21 on the left and right, are provided in equal numbers at positions symmetrical to the central rib 21 on the left and right, and have the same shape including the width W2, the length L2 in the vertical direction, the lower end position, and the upper end position, any of these may not be the same, a configuration where these are not the same may be adopted. Furthermore, although the present invention has been exemplified as being applied to a battery case 1 for a lead-acid battery and a mold 31 used for injection molding the battery case 1, the present invention may also be applied to battery cases other than lead-acid batteries and molds used for injection molding battery cases other than lead-acid batteries. [Explanation of symbols]

[0038] 1 battery case Battery containers according to reference examples 1A and 1B 3 Plate group 4 Cell Room 11 The First Wall 12 Second wall (inner wall of the battery container facing the partition wall 13) 13 Partition Wall 21 Center rib on both sides (first rib) 22 Left and right ribs (second ribs) 31 Mold (mold for battery case) 31A, 31B Molds related to reference examples L0 Height of partition wall (height of battery case) L1 Length of the center rib L2 Length of left and right ribs W1 Width of the center rib W2 Width of left and right ribs SM molten resin SP mold internal space

Claims

1. A storage battery comprising a battery case whose internal space is divided into a plurality of cell chambers by partition walls, and a gate mark formed by injection molding at the bottom of the battery case, The battery case has a plurality of ribs extending in the vertical direction at least on an inner wall of the battery case facing the partition wall, A storage battery characterized in that the central rib of the plurality of ribs is longer in the vertical direction and wider in the horizontal direction than the remaining ribs.

2. 2. The storage battery according to claim 1, wherein the plurality of ribs have the same amount of protrusion from the inner wall of the battery case on which the ribs are provided.

3. Among the plurality of ribs, the ribs other than the left-right central rib are provided in equal numbers at symmetrical positions with respect to the left-right central rib, and have the same shape including width, vertical length, lower end position, and upper end position, The left and right arrangement intervals of all the ribs, including the left and right central ribs, are the same.

3. The storage battery according to claim 1 or 2.

4. A mold for a battery case is used to manufacture, by injection molding, a battery case whose internal space is divided into a plurality of cell chambers by partition walls, The mold for the battery case has a gate for injecting molten resin at a position corresponding to the lower part of the battery case, and has an internal space connected to the gate and corresponding to the battery case, the internal space includes a space in which a plurality of ribs extending in the vertical direction are provided on at least an inner wall of the battery case facing the partition wall, A mold for a battery container, wherein the rib at the center of the left and right sides of the plurality of ribs is longer in the vertical direction and wider in the horizontal direction than the remaining ribs.

Images