Abstract:
A seal type storage battery has a battery case which has a sealing equipment to seal an opened portion of an outer case, which holds an electricity generating element. It has a pressure-sensitive conductive rubber in the battery case, whose resistance is changed continuously depending on a rise of inner pressure of the battery case. A lead connecting with the pressure-sensitive conductive rubber is extended to outside from the battery case, and the lead outputs a pressure detecting signal to outside.

Description:
[0001]    This application is based on applications No. 94296 filed in Japan on Mar. 30, 2000 and No. 68336 filed in Japan on Mar. 12, 2001, the content of which incorporated hereinto by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to a seal type storage battery such as a nickel-cadmium storage battery, a nickel metal hydride type storage battery or the like, especially improving a seal type storage battery having a pressure detector detecting inner pressure of the battery.  
           [0003]    A seal type storage battery such as a nickel-cadmium seal type storage battery, a nickel metal hydride storage battery or the like produces oxygen gas at a positive electrode when close to charge up, and in some cases hydrogen gas is produced at a negative electrode, so that inner pressure of the battery increases. For this reason, this kind of batteries has a relief valve equipment, which exhausts the gas out of the battery when the inner pressure is beyond predetermined pressure and seals again when the inner pressure is lower than the predetermined pressure after exhausting.  
           [0004]    In this case, it occurs decrease of battery capacity due to decrease of electrolyte in accordance with the process of charge-discharge cycles. Therefore various charging methods preventing overcharge are employed. For example, it is employed that a method, so-called - delta-V method, controls the charge with detecting decreased voltage delta-V from a peak point in accordance with a phenomenon which charged voltage shows the peak point in end of charging. It is also employed that a method controls the charge with detecting surface temperature of the battery in accordance with phenomenon that the surface temperature increases with the process of the charge.  
           [0005]    However the charged voltage depends on charging current or ambient temperature much, so that the delta-V method described above has a problem that dispersion of the detected delta-V value occurs overcharge. On the other hand, the method that controls the charge with detecting the surface temperature of the battery described above can detects the difference of the temperature comparatively with accuracy when charging current is small, but the temperature in short time charging increases quickly so that the method has a problem that delaying to detect the increasing temperature occurs overcharge.  
           [0006]    Therefore it was proposed that a method controls the charge by detecting a rise of inner pressure of the battery due to the charge, for example in Japanese Raid-Open Patent Publication No. TOKU-KAI-HEI 5-153,734 (1993), Japanese Raid-Open Patent Publication No. TOKU-KAI-HEI 5-36,442 (1993) etc. However in the method proposed in Japanese Raid-Open Patent Publication No. TOKU-KAI-HEI 5-153,734 (1993), a strain gauge is attached to the battery with adhesive to detect the inner pressure, and then deformation of the battery case is converted into variation of resistance so that its charging is controlled by detecting the variation of resistance. In this case, it has a problem that it cannot prevent overcharge sufficiently, since it cannot detect the inner pressure directly so that detection of the inner pressure delays, and sensitivity of the detection depends on condition of the attachment of the strain gauge so that it cannot detect the inner pressure certainly.  
           [0007]    On the other hand, in the method proposed in Japanese Patent Application HEI 5-3644, 1993, it has a problem that it cannot be used repeatedly when it cut the charging current directly in charging with huge amount of the charging current, since a detection signal detected by a pressure detector controls a switching device disposed in a charging circuit to cut the charging current directly so that the switching device can be broken. In addition, it is difficult that the pressure detector disposed in the trough operates stably for a long time, so that it makes difficult to detect its inner pressure with accuracy to protect the battery effectively. It causes that the detector is disposed under very hard circumstance such as hard variation of pressure or temperature, so that the detector is apt to aging. Further the detector is disposed under the circumstance to be exposed with electrolyte, which causes leakage.  
           [0008]    Therefore to solve these problems mentioned above, the object of the present invention is to provide a seal type storage battery that can detect inner pressure of the battery caused by charging directly not to occur overcharge.  
           [0009]    The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.  
         SUMMARY OF INVENTION  
         [0010]    To achieve the objects mentioned above, the seal type storage battery of this invention has a pressure-sensitive conductive rubber whose resistance is changed continuously depending on a rise of inner pressure of the battery case is disposed in the battery case, a lead connecting with the pressure-sensitive conductive rubber which is disposed with extended to outside from the battery case, the lead disposed with extended to outside from the battery case outputs a pressure detecting signal.  
           [0011]    Since the seal type storage battery has the pressure-sensitive conductive rubber whose resistance is change continuously depending on the rise of inner pressure of a battery case so that the detection does not delay because the inner pressure can be output as the detecting signal immediately. In addition, the pressure-sensitive conductive rubber detecting the pressure has superior resistance for transmutation of pressure and temperature so that the structure can prevent its aging. Further, as shown in FIG. 4, the pressure-sensitive conductive rubber has a characteristics that its resistivity changes in accordance with load (pressure) sensitively is so high that it can detect rise of the inner pressure with accuracy. Especially, the resistitvity is extremely sensitive in early stage at which load operates, so that the increasing inner pressure can be detected more precisly. Further, the pressure-sensitive conductive rubber shows superior water-proof such that it can prevent the degradation caused by the electrolyte effectively. Accordingly, the seal type storage battery according to the present invention can detect the inner pressure of the battery with accuracy and immediacy using the pressure-sensitive conductive rubber thus it prevent overcharging for this type of battery for a long term with certainty. Further more, the seal type storage battery has the lead connecting with the pressure-sensitive conductive rubber, which is disposed in the battery case and extended to outside, so that simply connecting the extended lead from the battery case with the control circuit of the charging circuit can cut the charging current, it makes the connecting work between the seal type storage battery and charging circuit simple and easy.  
           [0012]    In this case, the seal type storage battery according to the present invention has a sealing equipment which has a sealing sheet having an opened hole in the center and sealing an opened hole of the outer case via an insulative gasket and an electrode cap as an outer terminal fixed on the outer surface of the sealing sheet, and an alkali-resisting rubber sheet is disposed between the sealing sheet and the electrode cap, wherein the pressure-sensitive conductive rubber is disposed in the position of the opened hole of the sealing sheet and sandwiched between the alkali-resisting rubber sheet and the electrode cap, so that the pressure due to gas produced in the battery can convey to the pressure-sensitive conductive rubber via the alkali-resisting rubber. Therefore the gas pressure produced in the battery can be conveyed to the pressure-sensitive conductive rubber immediately, and then it is output to out side as the electrical signal via the lead connected with the pressure-sensitive conductive rubber in an instant.  
           [0013]    Thereby, the seal type storage battery connected with the charging circuit can prevent overcharge, since the lead connecting with the pressure-sensitive conductive rubber disposed outside of the battery connects with the control circuit of the charging circuit so that the charging current can be cut immediately when the inner pressure of the battery is beyond the predetermined pressure value. In addition, even the sealing sheet has the opened hole in the center of it, the alkali-resisting rubber seals the opened hole so that the internal battery is retrain in airtight therefore the pressure-sensitive conductive rubber is not exposed to the alkali-ambient of the internal battery.  
           [0014]    In addition, the seal type storage battery may have a pressure-regulating valve equipment disposed between the sealing sheet which is a component of the sealing equipment and the electrode cap. The pressure-regulating valve equipment comprises a valve sealing the opened hole portion of the sealing sheet and an elastic body thrusting the valve to the opened hole. In the valve, the pressure-sensitive conductive rubber is disposed at position facing the opened hole portion of the sheet via an alkali-resisting rubber. The seal type storage battery can cut the charge current immediately by detecting rise of the inner pressure of the battery with the pressure-sensitive conductive rubber disposed inside of the valve. Further, in the seal type storage battery, the pressure-regulating valve can exhaust the gas in the battery case to outside by opening the valve instantly, even the charge current cannot be cut immediately when the inner pressure rising because of error at the pressure-sensitive conductive rubber.  
           [0015]    Further more, the seal type storage battery may seal the opened portion of the outer case with the sealing sheet via a insulative gasket. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 shows a cross section view of the process to produce the sealing equipment of the present invention having the pressure-sensitive conductive rubber.  
         [0017]    [0017]FIG. 2 shows a cross section view of the finished sealing equipment of the present invention having the pressure-sensitive conductive rubber.  
         [0018]    [0018]FIG. 3 shows a partial cross section view of the main part of the nickel-cadmium storage battery having the seal equipment of FIG. 2.  
         [0019]    [0019]FIG. 4 shows the relationship of the pressure-sensitive conductive rubber of the present invention between compression pressure (load stress) and resistivity.  
         [0020]    [0020]FIG. 5 shows a block diagram of the charging circuit to charge the seal type storage battery according to the present invention.  
         [0021]    [0021]FIG. 6 shows a cross section view of the finished sealing equipment of another embodiment having the pressure-sensitive conductive rubber.  
         [0022]    [0022]FIG. 7 shows a cross section view of the completed sealing equipment having the pressure-sensitive conductive rubber of another embodiment according to the present invention.  
         [0023]    [0023]FIG. 8 shows a magnified cross section view of the valve of the sealing equipment shown in FIG. 7.  
         [0024]    [0024]FIG. 9 shows a cross section view of the valve under pressure shown in FIG. 8.  
         [0025]    [0025]FIG. 10 shows a cross section view of the completed sealing equipment having the pressure-sensitive conductive rubber of another embodiment according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    An embodiment of the present invention applying to the nickel-cadmium seal type storage battery is described with FIG. 1-FIG. 3 below. Here, FIG. 1 shows a cross section view of the process to produce the sealing equipment of the present invention having the pressure-sensitive conductive rubber, FIG. 2 shows a cross section view of the finished sealing equipment of the present invention having the pressure-sensitive conductive rubber, and FIG. 3 shows a partial cross section view of the main part of the nickel-cadmium storage battery having the sealing equipment of FIG. 2.  
         [0027]    1.P roducing the Sealing Equipment  
         [0028]    First, preparing a lead  12  having a pressure-sensitive conductive rubber  11  (for example Inastmar manufactured by Inaba Rubber Inc.), covering covers one side of the pressure-sensitive conductive rubber  11  joined to the lead  12  with an insulative sheet  13 , attaching an alkali-resisting rubber (for example ethylene-propylene diethylene rubber (EPDM)) sheet  14  attached to the other side not joined to the lead  12 , then a pressure-sensor is produced. The pressure-sensitive conductive rubber  11  is mainly made of a pressure-sensitive conductive material having a character that decrease its resistivity in accordance with the increase of the pressure (load stress) as shown in FIG. 4. And one side end of the lead  12  exposes a pair of core wire  12   a,    12   b.    
         [0029]    Next, preparing a sealing sheet  15  with an opened hole  15   a  in the center, and a electrode cap  16  having a projection  16   a  in the center with a pierced hole  16   b  at its bottom, then disposing the pressure-sensor described above between the sealing sheet  15  and the electrode cap  16 . In the battery of this embodiment, the electrode cap  16  explained as a positive electrode. In this case, after the lead  12  of pressure-sensor is inserted into the pierced hole  16   b  of the electrode cap  16 , disposing the pressure-sensitive conductive rubber  11  to position at the opened hole  15   a  of the sealing sheet  15 . Subsequently, the pressure-sensitive conductive rubber  11  is sandwiched between the sealing sheet  15  via the alkali-resisting rubber  14  and the electrode cap  16  by caulking the periphery  15   b  of the sealing sheet  15  with bending. As described above, the pressure-sensitive conductive rubber  11  sandwiched between the sealing sheet  15  and the electrode cap  16  has an advantageous feature to locate at predetermined position with certain. Further, since the pressure-sensitive conductive rubber  11  is disposed such that the opposite side of the surface facing the opened hole  15   a  is surface-contacting with the electrode cap  16 , the electrode cap  16  can firmly receive the load affecting to the surface facing to the opened hole  15   a  and detect the pressure with accuracy. Next, producing a sealing equipment  10  by attaching an insulative gasket  17  to around the portion of the caulked sealing sheet  15 .  
         [0030]    2. Producing the Nickel-cadmium Storage Battery  
         [0031]    On the other hand, applying positive activating material slurry having a positive activating material mainly made of nickel hydroxide and adhesive on the both side of a core plate made of a punching metal, after drying, producing a nickel positive electrode plate by cutting it into a predetermined form. In addition, applying negative activating material slurry having a negative activating material mainly made of cadmium oxide and adhesive on the both side of a core plate made of a punching metal, after drying, producing a cadmium negative electrode plate by cutting it into a predetermined form.  
         [0032]    Next, producing a rolled electrode agglomerate  21  by rolling these the nickel positive electrode and the cadmium negative electrode with a separator between of them in a roll shape, then welding a positive collector  21   a  onto the positive core plate exposed upper surface of the rolled electrode agglomerate  21 , and welding a negative collector (not shown) onto the negative core plate exposed lower surface of the rolled electrode agglomerate  21 . Next, disposing the rolled electrode agglomerate  21  into an outer case  22  formed in a drum shape having a bottom (the outside of the bottom is a negative electrode terminal) made of iron with nickel plating.  
         [0033]    After then, spot-welding a positive collector lead  21   b  extended from the positive collector  21   a  to the bottom of the sealing sheet  15  of the sealing equipment  10  described above. Next, after forming a circular groove portion  22   a  by drawing to the upper outline part of the outer case  22 , attaching the sealing equipment  10  into an opened portion of the outer case  22  with disposing the insulative gasket  17  onto the circular groove portion  22   a.  Next, producing the nickel-cadmium storage battery  20  by caulking the opened edge portion  22   b  of the outer case  22  toward inside with sealing the battery.  
         [0034]    3. Connecting with the Charging Circuit  
         [0035]    Next, an embodiment that disposes the nickel-cadmium storage battery  20  produced as mentioned above with connecting with a charging circuit is described with FIG. 5 below.  
         [0036]    Here, the charging circuit has a DC source  29 (also the DC source can be used a current source commutating an AC source) providing the charging current to the nickel-cadmium storage battery  20 , a switching circuit  27  applying or cut the current source  29  to the nickel-cadmium storage battery  20 , and a control circuit  25  judging whether the inner pressure of the nickel-cadmium battery  20  is higher than a predetermined threshold or not and outputting a cutting signal to the switching circuit  27  when the inner pressure is higher than the threshold. The switching circuit  27  may be a switching device as a semiconductor device such as a transistor or FET or the like. The switching circuit  27  makes contact with AC current or cut the AC current with controlled by On or Off of the signal provided from the control circuit  25 . The switching device applied to the semiconductor switching device can be used for a long term stably without breakdown even in use charging with high-current repeatedly. This is because the semiconductor switching device does not break due to the On and Off operation of switching, which differs from a switching device having mechanical contact.  
         [0037]    When the nickel-cadmIum storage battery  20  is connected with the charging circuit described above, connecting the positive side of the DC source with the projection (positive terminal)  16   a  of the electrode cap  16  of the nickel-cadmium storage battery  20  via the switching circuit, connecting the negative side of the DC source with the bottom (negative terminal) of the outer case  22 . On the other hand, control circuit  25  connects with one core wire  12   a  of lead wire  12  which connects with the pressure-sensitive conductive rubber  11  and is extended from the pierced hole  16   b  of the electrode cap  16  to outside of the battery. The other core wire  12   b  is connected with connecting portion of the DC source  20  and the negative electrode of the battery  20 . Therefore the battery  20  connects with the charging circuit.  
         [0038]    4. Charge Operation  
         [0039]    Next, the operation of the charging circuit connecting with the storage battery  20  as mentioned above is described below. First, switching on a DC source switch (not shown) makes the switching circuit  27  on state, then the DC source  29  provides the charging current (constant current) with the battery  20 . With keeping constant-current charging, the charged voltage rises, and when close to the end of charging, the inner pressure due to gas produced in the battery rises. When the inner pressure rises, the resisitivity of the pressure-sensitive rubber  11  drops as shown in FIG. 4.  
         [0040]    Thereby, the voltage value through the pressure-sensitive rubber  11  decreases. The control circuit  25  does not output the detecting signal when the voltage value is higher than the predetermined threshold so that charging is kept, and output the detecting signal to the switching circuit  27  when the voltage value is lower than the threshold. Therefore, the switching circuit  27  is in off state so that the charging current is not provided with the battery  20 . Accordingly the battery  20  is prevented overcharge.  
         [0041]    5. Another Embodiment  
         [0042]    Although it is explained that the embodiment described above has the pressure-sensitive conductive rubber  11  sandwiched between the sealing sheet  15  via the alkali-resisting rubber  14  and the electrode cap  16 , the pressure-sensitive conductive rubber can be disposed in the negative electrode side. In this case, as shown in FIG. 6, an insulative sheet  33  covers one side of a pressure-sensitive conductive rubber  31  joined to a lead  32 , and an alkali-resisting rubber sheet  34  is attached to the other side not joined to the lead  32 , then a pressure-sensor is produced. Next, the pressure sensor is disposed between a sealing sheet  35  and a electrode cap  36 . In this sealing equipment  30 , the electrode cap  36  explained as a negative electrode.  
         [0043]    In this case, inserting one of a core wire  32   a  of the lead  32  extended from the pressure-sensitive rubber  31  into the pierced hole  36   b  of the electrode cap  36 , and disposing the pressure-sensitive conductive rubber  31  to position at an opened hole  35   a  of the sealing sheet  35  after welding the other core wire  32   b  to the bottom of the projection  36   a  of the electrode cap  36 . Subsequently, the pressure-sensitive conductive rubber  31  is sandwiched between sealing sheet  35  via the alkali-resisting rubber  34  and the electrode cap  36  by caulking the periphery  35   b  of the sealing sheet  35  with bending. Next, producing a sealing equipment  30  by attaching an insulative gasket  37  to around the caulked portion of the sealing sheet  35 .  
         [0044]    Next, welding a negative collector onto a rolled electrode agglomerate produced as same as described above, and welding a positive collector onto the lower surface of the rolled electrode agglomerate, then, disposing the rolled electrode agglomerate to be held into a cylindrical shaped and bottom closed outer case made of iron with nickel plating (in this case, the outer surface of the bottom is a positive electrode terminal). Consequently, spot-welding a positive collector lead extended from the negative collector to the bottom of the sealing sheet  35  of the sealing equipment  30 , after forming a drawn portion by drawing to the upper outline part of the outer case, attaching the sealing equipment into an opened portion of the outer case with disposing the insulative gasket  37  onto the drawn portion. Next, producing the nickel-cadmium storage battery with sealing the battery by caulking the opened edge portion of the outer case toward inside.  
         [0045]    In this another embodiment of the nickel-cadmium storage battery, the other side of the core wire  32   b  of the lead  32  extended from the pressure-sensitive rubber  31  is welded to the bottom of the projection of the electrode cap  36 , so that the lead connecting with the control circuit  25  (See FIG. 5) of the charging circuit is only the one side of core wire  32   a,  it makes connecting work more easier.  
         [0046]    Also, the sealing equipment  30  described above can be disposed in the bottom of the cylindrical outer case and a conventional sealing equipment can be disposed in the top of the outer case. In this case, the conventional sealing equipment has a structure that has a pressure-regulating valve having a valve to shut a hole for exhaust formed in center of a sealing sheet and a spring to thrust the valve, between the sealing sheet and a electrode cap which is a positive electrode. Thus disposing the conventional sealing equipment, the pressure-regulating valve can work even the pressure-sensitive conductive rubber  31  disposed in the sealing equipment  30  is not in operate, so that the safety of the battery is further improved.  
         [0047]    As described above, according to the prevent invention the seal type storage battery has an alkali-resisting rubber sheet  14 ( 34 ) between a sealing sheet  15 ( 35 ) and an electrode cap  16 ( 36 ), wherein a pressure-sensitive conductive rubber  11  ( 31 ) is disposed in position of an opened hole  15   a ( 35   a ), which is an opened hole portion, on the sealing sheet  15 ( 35 ) and sandwiched between the alkali-resisting rubber sheet  14 ( 34 ) and the electrode cap  16 ( 36 ), so that the pressure due to gas produced in the battery can convey to the pressure-sensitive conductive rubber  11 ( 31 ) via the alkali-resisting rubber  14 ( 34 ). Therefore the gas pressure produced in the battery can be conveyed immediately, and then it is output to outside or the battery as an electrical signal via a lead wire  12 ( 32 ), which Is a lead, connected with the pressure-sensitive conductive rubber  11 ( 31 ) in an instant.  
         [0048]    Thereby, connecting the lead  12 ( 32 ) extended to the outside of the battery with a control circuit  25  of a charging circuit, so that the control circuit  25  can cut the charging current immediately with operation of a switching circuit  27  when the inner pressure of the battery is beyond a predetermined value input in the control circuit  25 . Therefore, the seal type storage battery  20  connected with the charging circuit can prevent overcharge.  
         [0049]    6. Another Embodiment  
         [0050]    Further more, the sealing equipment of another embodiment according to the present invention which has a pressure-sensitive conductive rubber and a pressure-regulating valve is shown in FIG. 7. The sealing equipment  50  shown in FIG. 7 has the pressure-regulating valve  60  having a valve  61  and an elastic body  62  between the sealing sheet  55  and electrode cap  56 .  
         [0051]    The sealing sheet  55  and the electrode cap  56  are produced with pressing metal sheet. The sealing sheet  55  has a projection  55   c  projecting below in center, and has opened hole  55   a  in the center area of the lower surface of the projection  55   c.  The electrode cap  56  has a projection  56   a  projecting upward in the center area. Here, the projection  56   a  is a positive electrode in this electrode cap  56 . In addition, the electrode cap  56  has an opened pierced hole  56   b  in the side surface of the projection  56   a . The pierced hole  56   b  serves as a port exhausting the gas in the battery case to outside when the pressure-regulating valve  60  operate, and also serves as a port to pull out the lead wire  52  connected with the pressure-sensitive conductive rubber  51  disposed inside of the valve  61  to outside. The sealing sheet  55  and the electrode cap  56  are laminated so as to form space inside by reentrant portion defined at their projections  55   c  and  55   a , which are projecting upward and downward respectively, by facing each other so that the valve  61  and the elastic body  62  are disposed in this space formed inside. In the sealing equipment  50 , after disposing the valve  61  and the elastic body  62  between the sealing sheet  55  and electrode cap  56 , the sealing sheet  55  and the electrode cap  56  are coupled by bending and then caulking the periphery  55   b  of the sealing sheet  55 . Altenatively the sealing sheet  55  and the electrode cap  56  may be connected by spot-welding at peripheral portion.  
         [0052]    The pressure-regulating valve  60  opens the valve when the inner pressure of the battery case is higher than the predetermined pressure to prevent that the extremely high pressure breaks the outer case. The pressure-regulating valve  60  has the valve  61  which seals the opened hole  55   a  of the sealing sheet  55 , and the elastic body  62  which apply a force to the valve  61  toward the opened hole  55   a.    
         [0053]    As shown a magnified cross section view in FIG. 8, the valve  61  has the pressure-sensitive conductive rubber  51  inside. The valve  61  shown in FIG. 8 has a sheet material  63  coupled with the lower end of the elastic body  62 , a cylindrical body  64  fixed on the lower surface of the periphery of the sheet material  63 , and the alkali-resisting rubber sheet  54  which is fixed on the bottom of the cylindrical body  64  and seals the bottom opening of the cylindrical body  64 . The valve  61  disposes a pressure-sensitive conductive rubber  51  in the space formed with the sheet material  63 , the cylindrical body  64  and the alkali-resisting rubber sheet  54 . In the valve  61 , the pressure-sensitive conductive rubber  51  is located at predetermined position by being fixed in the center portion of lower surface of the sheet material  63 . The sheet material  63  is preferably made of hard plastic sheet or metal sheet. This type of the sheet material  63  reduces errors caused by responsibility of the pressure-sensitive conductive rubber  51  for the gas pressure. In addition, in the valve  61 , the lead wire  52  connected with the pressure-sensitive conductive rubber  51  is pulled out to outside of the valve  61 . The lead wire  52  is pulled out through the pierced hole  56   b  of the electrode cap  56  to outside of the battery. As shown in FIG. 7, the valve  61  is disposed at the position such that it seals the opened hole  55   a  of the sealing sheet  55  and the pressure-sensitive conductive rubber  51  faces the opened hole  55   a . Therefore the pressure-sensitive conductive rubber  51  detects rise of the inner pressure of the battery. The pressure detecting signal detected by the pressure-sensitive conductive rubber  51  is outputted via the lead wire  52 .  
         [0054]    In addition, in the valve  61  shown In FIG. 8, the inner shape of the cylindrical body  64  is larger than the outer shape of the pressure-sensitive conductive rubber  51  such that the pressure-sensitive conductive rubber  51  does not contact the cylindrical body  64 . As for the valve  61 , the height of the cylindrical body  64  is higher than the thickness of the alkali-resisting rubber sheet  54  such that a gap is formed between the pressure-sensitive conductive rubber  51  and the alkali-resisting rubber sheet  54  not to contact the pressure-sensitive conductive rubber  51  with the alkali-resisting rubber sheet  54 . The gap between the pressure-sensitive conductive rubber  51  and the alkali-resisting rubber sheet  54  is designed 0-2 mm, preferably 0.2-1 mm, most preferably 0.5 mm. In this valve  61 , given the inner pressure of the battery rising and the alkali-resisting rubber sheet  54  compressed, as shown in FIG. 9, the alkali-resisting rubber sheet  54  is deformed and the pressure-sensitive conductive rubber  51  is compresses thereby the pressure is detected. In normal battery state, the surface of the pressure-sensitive conductive rubber  51  does not contact with the cylindrical body  64  or the alkali-resisting rubber sheet  54 , so that the valve  61  of this structure can prevent error detection of the inner pressure certainly. Also, the pressure-sensitive conductive rubber  51  may be disposed with contacting with the cylindrical body  64  or the alkali-resisting rubber sheet  54 .  
         [0055]    One end of the elastic body  62  is joined to the valve  61 , the other end is joined to the bottom of reentrant potion of the electrode cap  56 . The elastic body  62  impels the valve toward the opened hole  55   a . The elastic body  62  shown in the figure is a coil spring with elastic line-shaped material. The elastic body  62  using a spring is fixed to the valve  61  and the electrode cap  56  by welding or adhering. Thus the elastic body  62  disposed between the sealing sheet  55  and the electrode cap  56  disposes the valve  61  to predetermined position, and seals the opened hole  55   a  with pussing and compressing the valve  61  to the bottom of reentrant potion of the sealing sheet  55 . The elastic body  62  has optimal elastic force to open the valve with moving the valve  61  when the inner pressure of the battery is higher than predetermined pressure.  
         [0056]    In addition, another embodiment in which a rubbery elastic body applies the elastic body is shown in FIG. 10. The sealing equipment  70  shown In FIG. 10 has the pressure-regulating valve  80 , which has the valve  81  having the pressure-sensitive conductive rubber  71  inside and the elastic body  82  which is the rubbery elastic body, between the sealing sheet  75  and the electrode cap  76 . In the valve  81 , the pressure-sensitive conductive rubber  71  is fixed to the lower surface of the sheet material  83  joined to the lower end of the elastic body  82 , and disposed in the space formed with the sheet material  83 , the cylindrical body  84  and the alkall-resisting rubber sheet  74 . The valve  81  is disposed to seal the opened hole  75   a  of the sealing sheet  75  via the elastic body  82 . For example, the rubbery elastic body, which is the elastic body  72 , can be fixed to predetermined position with adhered to the valve  81  and the electrode cap  76 . The lead wire  72  connected with the pressure-sensitive conductive rubber  71  is extended from the pierced hole  76   b  of the electrode cap  76  to outside of the battery, and outputs the pressure detecting signal detected in the pressure-sensitive conductive rubber  71 . In the sealing equipment  70 , the sealing sheet  55  and the electrode cap  56  are also coupled by caulking the periphery  75   b  of the sealing sheet  75  with bending.  
         [0057]    Although it is not shown, the sealing equipment shown in FIG. 7 and FIG. 10 is attached to the opened portion of the outer case after the insulative gasket is attached to periphery of the calked portion of the sealing sheet. Then sealing the battery by caulking the opened edge portion of the outer case toward inside. In addition, as shown in FIG. 7 and FIG. 10, connecting the lead wire  52  ( 72 ) extended from the pierced hole  56   b  ( 76   b ) of the electrode cap  56  ( 76 ) to outside of the battery with the charge circuit (not shown). Connecting one core wire  52   a  ( 72   a ) of the lead wire  52  ( 72 ) with the control circuit of the charge circuit, connecting another core wire  52   b  ( 72   b ) with the connector of the power source and the negative electrode of the battery.  
         [0058]    Although it is not shown, in addition, when the electrode cap be used as negative electrode, one lead wire can be extended from the pierced hole of the electrode cap to outside of the battery, and another core wire of the lead wire can be connected electrically in the electrode cap with welding or the like, in the sealing equipment. The seal type storage battery makes connecting work easier, cause only one core wire of the lead wire extended to outside should be connected with the control circuit of the charge battery.  
         [0059]    The sealing equipment described above outputs the pressure detecting signal to the charge circuit via the lead extended to outside with detecting ride of the inner pressure of the battery by the pressure-sensitive conductive rubber disposed inside of the valve. The control circuit of the charge circuit cuts the charge current to prevent overcharge in the seal type storage battery, when the inner pressure of the battery becomes higher than the predetermined pressure. In addition, the sealing equipment prevents the inner pressure of the battery becomes extremely high pressure with the pressure-regulating valve opening the valve, even the control circuit does not cut the charge current in some reasons when the inner pressure is higher than the predetermined pressure. Therefore, predetermined pressure with the pressure-regulating valve opening is set higher than the predetermined pressure with the control circuit cutting the charge current.  
         [0060]    States of the battery attached the sealing equipment described above, in which the charge current is cut by the pressure detecting signal from the pressure-sensitive conductive rubber and the gas is exhausted by the pressure-regulating valve with opening the valve, was experimented below.  
       EXAMPLE 1  
       [0061]    The batteries A-D (500 mAh) having the sealing equipment shown in Fig. 7 were produced. The inner pressure to stop charging with the pressure detecting signal detected by the pressure-sensitive conducting rubber were set 0.6 MPa, 0.8 MPa, 1.0 MPa and 1.2 MPa respectively. In addition, in the batteries A-D, the inner pressure to operate the pressure-regulating valve opening the valve was set 1.5 MPa. These batteries were charged with the charge current  10  A. The charge current of all batteries A-D were cut when the Inner pressure of the batteries became each of the predetermined pressure, which were 0.6 MPa, 0.8 MPa, 1.0 MPa and 1.2 MPa respectively.  
       EXAMPLE 2  
       [0062]    Next, In the batteries A-D, the control circuit which stops charging with the pressure detecting signal detected by the pressure-sensitive conducting rubber turned off, and these batteries A-D were charged with the charge current  10  A. It was confirmed that the gas was exhausted by the pressure-regulating valve with opening the valve, when the inner pressure became 1.5 MPa or over 1.5 MPa.  
         [0063]    Here, in the embodiments described above, although the present invention is explained to apply to the nickel-cadmium storage batteries, this invention can also apply to a nickel metal hydride seal type storage battery or the like.  
         [0064]    As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within meets and bounds of the claims, or equivalence of such meets and bounds thereof are therefore intended to be embraced by the claims.