JPH063748B2 - Method for forming a window for monitoring the state of electrolyte in a battery case - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a window on a side wall of a storage battery cell for monitoring an electrolytic solution state such as an amount or a specific gravity of the electrolytic solution. Is.

[Prior Art and Its Problems] A storage battery is loaded with an electrolytic solution. However, since the amount of such an electrolytic solution has a significant relationship with the performance of the storage battery and leakage, it is always within a certain range. It needs to be managed as it is. In general, it is preferable to give consideration to the storage battery cell so that the liquid level of the electrolytic solution can be monitored from the outside.

The simplest way to allow the liquid level of the electrolyte to be monitored from the outside is to construct the storage battery cell itself from a transparent or translucent material. However, in this case, not only the liquid level of the electrolytic solution but also the entire inside of the battery case can be seen through. Therefore, especially in a storage battery that has been used for a long period of time, the inside of the battery case becomes ugly due to the deterioration of the electrode plate, etc., or the dropping of the active substance from the electrode plate, etc., and this is visible from the outside. , Which results in a bad appearance of the storage battery.

Under these circumstances, storage battery manufacturers usually take measures to make only the part of the battery case showing the liquid level of the electrolytic solution transparent or semi-transparent while making other parts opaque. .

For example, in Japanese Utility Model Publication No. 29-12442, a paint is applied in order to make the battery case opaque except for the upper and lower parts of the normal liquid surface of the electrolytic solution while forming the battery container with a transparent or translucent synthetic resin. Techniques for doing so are disclosed.

However, according to the above-mentioned conventional technique, not only the process of applying a coating to a predetermined area becomes complicated, but also the coating may drop off due to long-term use of the storage battery or friction with other objects, and the like. This may result in unaesthetic appearance.

Next, in JP-B-40-27890, after the main part of the battery case is injection-molded with, for example, an opaque resin, this is inserted into a mold, and a transparent resin is poured into the mold to make the transparent part of the battery case. A technique for forming a part is disclosed. The transparent portion is for allowing the liquid surface of the electrolytic solution to be seen through from the outside.

However, according to the above-described conventional technique, the interface between the transparent portion and the opaque portion extends over the entire circumference of the battery case or over a relatively long distance, and the resins forming the respective portions are different from each other, so that they are joined to each other. As a result, there is a drawback that the reliability is poor and, as a result, the reliability against leakage of the electrolytic solution is poor.

Next, Japanese Utility Model Publication No. 38-2333 and Japanese Utility Model Publication No. 38-
Japanese Patent No. 6045 discloses a structure in which an opaque battery case is formed so that a hole penetrating the side wall is formed, and then a liquid level transparent body having a transparent portion is fitted into the hole. Particularly, in the former related art, the liquid level see-through member is fitted into the hole via packing, and in the latter related art, a fitting method using screws is adopted.

However, none of the above-mentioned conventional techniques involves the work of inserting the liquid level transparent body into the hole formed in the side wall of the battery case, and such an inserted state can completely prevent liquid leakage. Therefore, the work becomes complicated and the manufacturing efficiency is lowered. In addition, the structure in which a separately prepared liquid surface see-through member is fitted into the hole of the battery case has low reliability against liquid leakage even if packing or screws are adopted in the fitting portion, and in particular, the storage battery has been used for a long time. Later, the problem of liquid leakage becomes more noticeable.

The structure that allows the inside of the battery case to be seen through can be applied not only to monitor the amount of electrolyte, but also to monitor the condition of the electrolyte, including its specific gravity. Even if it is a structure for doing, you will encounter similar problems.

OBJECTS OF THE INVENTION Therefore, the present invention intends to provide a method of forming an electrolyte solution monitoring window in a storage battery cell, which can solve the problems encountered by the above-mentioned various conventional techniques. Is.

In particular, the present invention advantageously seeks to solve the problem of liquid leakage at the interface between the electrolyte condition monitoring window and other portions.

[Means for Solving the Problems] The present invention is directed to a method for forming a window for monitoring a state of an electrolytic solution in a storage battery cell having a side wall and a bottom wall. It is characterized by including the step of. That is, (1) a step of preparing an accumulator battery case which is made of an olefin resin and has a hole penetrating the side wall, (2) an inside of the hole while surrounding a peripheral wall portion defining the hole Arranging a pair of molding dies so as to sandwich the side wall so as to form a cavity positioned at (3) Inside the cavity, at least an optical solution state monitoring window, Injecting a permeable olefin resin, and (4) separating the molding die from the side wall after the injected olefin resin is solidified.

[Operation] In the present invention, after the battery case having the hole penetrating the side wall is obtained, the hole is formed in the cavity formed by the pair of molding dies arranged so as to sandwich the side wall. Is located. Then, at least a light-transmitting olefin resin is injected into the cavity, and an electrolyte solution state monitoring window corresponding to the shape of the cavity is formed of the olefin resin.

[Effects of the Invention] According to the present invention, the storage battery battery case is made of an olefin resin, and the olefin resin is similarly injected so as to fill the hole provided so as to penetrate the side wall of the battery, and the electrolytic solution is injected. The condition monitoring window is formed by so-called "secondary" molding. Injection molding is then applied to the "secondary" molding of the electrolyte status monitoring window. Therefore, the injection pressure of the resin into the cavity formed by the molding die can be sufficiently increased, and both the battery case and the electrolytic solution state monitoring window are made of an olefin resin, which is advantageously integrated. As a result, a strong and highly reliable joint can be obtained. Therefore, the problem of liquid leakage does not occur during long-term use.

Further, the formation of the electrolyte state monitoring window by the "secondary" molding using the mold can be efficiently proceeded.

Forming the electrolyte solution monitoring window in such a shape that the resin forming the electrolyte solution monitoring window has portions in contact with both sides of the peripheral wall that defines the hole is effective in further preventing leakage. Target. In addition, it is also effective to further prevent liquid leakage by providing an uneven shape at the interface where the resin forming the electrolyte solution monitoring window and the battery case are in contact with each other.

In addition, the electrolytic solution state monitoring window is formed by a process different from the manufacturing process of the storage battery battery case, and the outer shape thereof is determined by the cavity formed by the molding die. An arbitrary shape can be given to. For example, it is easy to adjust the wall thickness of the electrolyte condition monitoring window by using a molding die. For example, the wall thickness of the electrolyte condition monitoring window is thinner than the wall thickness of the battery case. You can also do it. In this way, when the thickness of the electrolyte state monitoring window is reduced, the inside of the battery case can be better seen even if the material has a relatively low transparency.

[Embodiment] FIGS. 1 to 4 are views for explaining one embodiment of the present invention. FIG. 1 is a perspective view showing the external appearance of a storage battery battery case obtained by carrying out an embodiment of the present invention. The embodiments described below relate to the case where a liquid level display window is formed as the electrolyte state monitoring window.

As shown in FIG. 1, the battery case 1 has a side wall 2 and a bottom wall 3. As indicated by the dotted line on the side wall 2, the battery case 1 is divided into, for example, 6 cells, and a liquid level display window 4 as an electrolyte state monitoring window is formed in association with each cell. ing. For the method of forming the liquid level display window 4,
A detailed description will be given later with reference to FIGS. 2 to 4.

The upper surface of the battery case 1 is closed by a lid 5. On the lid 5,
A liquid port 6 is provided corresponding to each cell formed in the battery case 1. The liquid port 6 is for injecting a liquid, and is closed by a liquid port plug (not shown) except for injecting the liquid. Further, the pole 5 is arranged in the lid 5 so as to penetrate therethrough.

The battery case 1 and the lid 5 are formed by injection molding using an olefin resin. In particular, among olefin resins, it is preferable that the battery case 1 is made of, for example, a polypropylene copolymer. This is because this material generally has a high impact resistance, while the transparency is relatively low. In addition, in order to give the battery case 1 an opaque or relatively low transparency state, the olefin resin may be colored by containing an appropriate pigment.

As shown in FIGS. 2 to 4, a through hole 8 is formed in the side wall 2 of the battery case 1. The hole 8 corresponds to, for example, a mold used for injection molding the battery case 1. It can be formed by giving the shape of. In this embodiment, the hole 8 has a vertically elongated oval shape so that the shape of the window 4 shown in FIGS. 1 and 3 can be inferred.
However, the shape of the hole 8 can be any shape such as a circle or a quadrangle. It should be noted that the hole 8 has a range of upper and lower limits of the liquid surface 10 when the liquid surface 10 of the electrolytic solution 9 shown in FIG. 2 and FIG. Is formed in such a position and size as to cover the.

After the battery case 1 in which the holes 8 are formed is prepared, as shown in the enlarged sectional view of FIG. 4, a pair of molds 11 and 12 is formed.
Are arranged with the side wall 2 sandwiched therebetween. Molds 11 and 1
2 forms a cavity 14 in which the hole 8 is located while surrounding the peripheral wall portion 13 defining the hole 8.

Next, at least the light-transmissive olefin-based resin to be the liquid level display window 4 is injected into the cavity 14 described above. This injected olefin resin is
It flows into the cavity 14 through the sprue 15 communicating with the cavity 14.

Next, after the olefin resin injected as described above and filled in the cavity 14 is solidified, the molds 11 and 1 are
2 is separated from the side wall 2. As a result, the liquid level display window 4 is formed so as to close the hole 8 as shown in FIG. 2, FIG. 3, and FIG. The olefin resin that constitutes the liquid level display window 4 is advantageously integrated with the olefin resin that constitutes the side wall 2 of the battery case 1.

When the second member is added by the so-called "secondary" molding on the preformed first member as in the case of forming the liquid level display window 4 described above, the first member It has been found that the strength of the mutual bonding is extremely high when both the first member and the second member are made of an olefin resin in particular. Currently, such joint strength is
It cannot be obtained with resins other than olefin resins.
Therefore, as described above, the olefin-based resin forming the liquid level display window 4 and the olefin-based resin forming the battery case 1 are firmly joined and advantageously integrated, whereby It is possible to obtain high reliability for liquid leakage prevention.

As can be seen from FIGS. 2 and 3, the liquid level display window 4
Is thinner than the side wall 2. Such control of the wall thickness can be arbitrarily performed depending on the shapes of the molds 11 and 12. The thin wall of the liquid level display window 4 means that even if the material has a relatively low transparency,
It means that light transmission can be provided. Therefore, even if the liquid level display window 4 is formed of the same olefin resin as the battery case 1, the liquid level display window 4 can be in a state in which the inside can be better seen through.

Further, the olefin resin that constitutes the liquid level display window 4 is
It does not have to be exactly the same as the olefin resin that constitutes the battery case 1. For example, as described above, when battery case 1 is made of a copolymer containing polypropylene, liquid level display window 4 is preferably made of a homopolymer or a random copolymer of polypropylene. This is because these polymers have higher transparency than ordinary copolymers. Further, the random copolymer is also more preferable because it is excellent in impact resistance.

FIG. 5 is a diagram for explaining another embodiment of the present invention.

The embodiment shown in FIG. 5 is characterized in that the olefin-based resin forming the liquid level display window 4a has portions in contact with both surfaces of the peripheral wall portion 13 defining the hole 8, respectively.
The shape of the mold for forming such a liquid level display window 4a can be easily inferred from the outer shape of the liquid level display window 4a, and therefore is not shown.

Liquid level display window 4a integrated with the side wall 2 in the above-described manner
According to this, since the interface area between the liquid level display window 4a and the side wall 2 increases, it is possible to expect higher performance in preventing liquid leakage.

FIG. 6 is a diagram for explaining still another embodiment of the present invention.

In the embodiment shown in FIG. 6, the liquid level display window 4b is
It has substantially the same shape as the liquid level display window 4a in the figure. The feature of this embodiment is that the interface between the olefin resin forming the liquid level display window 4b and the side wall 2 of the battery case 1 is provided with an uneven shape. That is, in FIG. 6, rough surfaces 16 are formed on both surfaces of the peripheral wall portion 13 that defines the hole 8. Such a rough surface 16 can be easily formed by, for example, a sandblast method. A V-shaped groove 17, for example, is formed on the inner peripheral surface defining the hole 8. The presence of such an uneven shape provided by the rough surface 16 and the groove 17 further enhances the integration of the liquid level display window 4b and the side wall 2.

The rough surface 16 and the groove 17 shown in FIG. 6 may be only one of them, or the positions where they are formed may be reversed. Further, as the means for imparting the uneven shape, other mechanical or chemical means can be adopted.

In each of the embodiments described above, it is intended to monitor the amount of the electrolytic solution 9 by directly showing the liquid level 10 of the electrolytic solution 9 through the liquid level display window 4 as shown in FIG. It had been. However, as shown by an imaginary line in FIG. 2, a float 33 that floats on the liquid surface 10 of the electrolytic solution 9 may be arranged so that the float 33 can be seen through the electrolytic solution display window 4. In this case, the float 33 is markedly colored so that the liquid surface 10 of the almost colorless and transparent electrolytic solution 9 is
It is possible to provide a display that is easier to see than when directly looking. The float 33 may be configured to move up and down while being guided by, for example, a guide rod 34 that extends vertically through the float 33.

Also, the liquid level display windows 4 and 4 in the illustrated embodiments
The vertical dimension of each of a and 4b is at least
The size was selected so that the upper limit and the lower limit of the liquid surface 10 could be shown. However, the vertical dimension of the liquid level display window does not necessarily have to be selected so as to cover the upper and lower limits of the liquid level. For example, when the float is used as in the embodiments described with reference to FIG. 7 and subsequent figures, the vertical dimension of the liquid level display window is set shorter than the length between the upper and lower limits of the liquid level. Even in this case, the normal state and the abnormal state of the liquid surface can be displayed.

Referring to FIGS. 7 and 8, at the position where the liquid level display window 4c is provided, inside the battery case 1, a float 18 which is vertically long and can float in the electrolyte solution. Are placed. The float 18 is freely placed in a guide member 19 in which the upper and lower limits of its ups and downs are defined.
About the upper half of the float 18, for example, a red colored region 20 is provided, and about the lower half thereof is, for example, a green colored region 21.
It is said that In FIGS. 7 and 8, the upper one of the two one-dot chain lines extending in the lateral direction indicates the upper limit liquid level 22 of the electrolytic solution, and the lower one is the lower limit liquid level 23. Is shown.

FIG. 7 shows the position of the float 18 when the electrolytic solution is in the state of the upper limit liquid level 22. In this state, the green colored region 21 can be seen through the liquid level display window 4c. On the other hand, FIG. 8 shows the position of the float 18 when the electrolytic solution is in the state of the lower limit liquid level 23. In this state,
The red colored region 20 can be seen through the liquid level display window 4c.

In the intermediate state between the state shown in FIG. 7 and the state shown in FIG. 8, both the red colored region 20 and the green colored region 21 may sometimes be visible from the liquid level display window 4c, and the decrease of the electrolyte may be reduced by 2%. It can be recognized by the position of the boundary line between the two colored regions 20 and 21. Even if the amount of the electrolytic solution decreases below the lower limit liquid level 23 of the electrolytic solution, the floating member 18 maintains the state shown in FIG. 8 due to the presence of the guide member 19, and the red colored region 20 has the liquid level display window. It can continue to be displayed via 4c.

Upper limit liquid level 22 and lower limit liquid level 2 shown in FIGS. 7 and 8.
As can be seen by comparing the distance between the liquid level display window 4c and the vertical dimension of the liquid level display window 4c, the vertical dimension of the liquid level display window 4c is the upper limit liquid level 22 and the lower limit liquid level 23. It is shorter than the distance.

In the embodiment shown in FIGS. 9 and 10, the float 24
Is rotatably provided around the fixed shaft 25. The rotation range of the float 24 is limited to a predetermined range by the upper limit stopper 26 and the lower limit stopper 27. A display member 28 extending in an arc shape is attached to the side opposite to the float 24 around the fixed shaft 25. This display member 28
Has, for example, a green colored region 29 formed on the top thereof,
A red colored region 30, for example, is formed underneath. Further, in FIGS. 9 and 10, 31 indicates the upper limit liquid level and 32 indicates the lower limit liquid level.

In the state shown in FIG. 9, the electrolytic solution has the upper limit liquid level 31. At this time, the float 24 contacts the upper limit stopper 26, and the display member 28 directs its green colored region 29 toward the liquid level display window 4d. Therefore, a green display can be seen from the liquid level display window 4d. On the other hand, in FIG. 10, the electrolytic solution has the lower limit liquid level 32, and the float 2
4 is in contact with the lower limit stopper 27. At this time, the display member 28 directs the red colored region 30 toward the liquid level display window 4d, and accordingly, the liquid level display window 4d.
Is displayed in red.

In the embodiment shown in FIGS. 9 and 10, the vertical dimension of the liquid level display window 4d is made smaller than that of the embodiment shown in FIGS. 7 and 8 described above. If the vertical dimension of the liquid level display window 4d is further reduced, the distance between the float 24 and the fixed shaft 25 may be further increased.

Like the embodiment shown in FIGS. 7 and 8, and further the embodiment shown in FIGS. 9 and 10, the liquid level display window 4
Reducing the size of c or 4d is advantageous in the following points. That is, even if a polypropylene homopolymer having relatively low impact resistance but high transparency is used as the material for the liquid level display window, the decrease in strength given to the entire battery case can be minimized.

In the various embodiments described above, the liquid level display windows 4, 4
As described above, the through holes 8 through which a, 4b, 4c, and 4d are to be formed are given a shape corresponding to the mold used for injection molding of the battery case 1, so that the injection of the battery case 1 is performed. Although they can be formed simultaneously at the molding stage, for example, after molding the battery case 1 without the holes 8, the side wall 2 thereof is formed.
In addition, for example, it can be formed by mechanical processing such as punching and cutting. In this way, when the holes 8 are formed after the battery case 1 is obtained, the following advantages can be expected.

First, the mold for molding the battery case does not need to consider the formation of the holes, so that the mold has a simple structure. Further, when a mold for forming the battery case is provided with a shape for forming a hole, the resin cannot smoothly flow in the portion where the hole is formed during injection molding. In particular, in normal injection molding, the gate for injecting the resin is located on the bottom side of the battery case, while the hole is generally formed in a relatively upper portion of the battery case, so that the hole from the gate is not formed. The flow path of the resin to reach the part tends to be long. Therefore, in combination with the above-mentioned poor flow of resin in the hole portion, heat is absorbed by the mold in the hole portion and its vicinity, and as a result, solidification of the resin is likely to occur quickly, and weld lines are generated. It is likely to cause problems such as. However, as described above, when the holes are formed after the battery case is obtained, the problem of the occurrence of weld lines and the like due to the fluidity of the resin can be advantageously solved. In addition, forming a hole after obtaining the battery case is easier to operate as compared with the case of forming the hole at the stage of forming the battery case, and thus the shape, size, and The position, etc. can be more easily selected as desired.

In addition, in the above-mentioned embodiment, the case where the liquid level display window for displaying the liquid amount of the electrolytic solution is formed as the electrolytic solution state monitoring window is described, but other electrolytic solution states, for example, specific gravity are monitored. The present invention is equally applicable to a method of forming a window for making

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of a storage battery battery case 1 obtained by applying an embodiment of the present invention. FIG. 2 is an enlarged sectional view taken along the line II-II in FIG. FIG. 3 is a perspective view showing the part shown in FIG. 2 with a part thereof cut away. Fourth
The figure is an enlarged cross-sectional view showing a state in which molding dies 11 and 12 for injection-molding a resin to be the liquid level display window 4 are arranged so as to sandwich the side wall 2. FIG. 5 is a view corresponding to FIG. 2, showing a part of the battery case 1 obtained by carrying out another embodiment of the present invention. FIG. 6 is an enlarged sectional view showing a part of the side wall 2 obtained by carrying out still another embodiment of the present invention. 7 and 8 show an embodiment in which the liquid level display window 4c is modified so that the float 18 can be seen. 9 and 10, the liquid level display window 4d has a float 24.
An embodiment modified so as to show the display member 28 interlocked with is shown. In the figure, 1 is a battery case, 2 is a side wall, 3 is a bottom wall, and 4 and 4.
a, 4b, 4c, 4d are liquid level display windows (electrolyte condition monitoring windows), 8 is a hole, 9 is an electrolytic solution, 10 is a liquid level, 11, 12
Is a molding die, 13 is a peripheral wall portion, 14 is a cavity, 16
Is a rough surface (uneven shape), 17 is a groove (uneven shape), 22, 3
1 is an upper limit liquid level, and 23 and 32 are lower limit liquid levels.

Claims (6)

[Claims] 1. A method for forming a window for monitoring an electrolytic solution state in a battery case having a side wall and a bottom wall, the hole being made of an olefin resin and penetrating the side wall. A step of preparing a storage battery battery case formed with, forming a cavity for positioning the hole inside while surrounding the peripheral wall portion defining the hole, a pair of molding dies, the side wall Placing in a sandwiched state, to be an electrolyte state monitoring window into the cavity, injecting at least a light-transmitting olefin resin, after solidification of the injected olefin resin, the A step of separating the molding die from the side wall, and forming a window for monitoring an electrolyte state in the storage battery battery case. 2. The method for forming an electrolyte solution condition monitoring window in a storage battery cell according to claim 1, wherein the thickness of the electrolyte solution condition monitoring window is smaller than that of the side wall. . 3. The olefin resin forming the window for monitoring the state of the electrolytic solution has a portion in contact with both surfaces of a peripheral wall portion defining the hole, respectively. Of forming a window for monitoring the state of electrolyte in the storage battery battery case of. 4. An uneven shape is provided on an interface at which the olefin resin forming the electrolyte state monitoring window and the storage battery case contact each other, and an uneven shape is given to the interface. A method for forming a window for monitoring the state of an electrolytic solution in the battery case according to any one of 1. 5. The olefin resin forming the window for monitoring the state of the electrolytic solution is selected from those having a relatively higher transparency than the olefin resin forming the battery case of the storage battery. Item 5. A method for forming an electrolytic solution state monitoring window in the storage battery cell according to any one of items 4 to 4. 6. The olefin resin forming the storage battery case and the olefin resin forming the electrolyte state monitoring window are both polypropylene based. A method of forming a window for monitoring the state of an electrolyte in the storage battery cell according to any one of items.