Abstract:
An object is to prevent leakage of an electrolysis solution and reduce pressure loss. All air cell cartridge includes a plurality of air cells each including a positive electrode material, a negative electrode material and an electrolysis solution layer holding an electrolysis solution and interposed between the positive electrode material and the negative electrode material and each being provided with an air flow path through which air passes so as to come into contact with the positive electrode material, wherein a leakage prevention material (S) is provided to absorb the electrolysis solution leaked from the electrolysis solution layer and swell so as to block up the air flow path ( 20 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an air cell cartridge mounted on a vehicle or the like and an air cell system. 
       BACKGROUND ART 
       [0002]    There is known a configurable air cell in which a plurality of unit cells of air cells arranged in series are housed in a battery case, the battery case having a structure in which water-repellent fillers are attached to ventilation holes in order to prevent liquid leakage at the time of over-discharge (for example, refer to Patent Literature 1). 
         [0003]    There is also known a button-type air cell having a structure in which an air diffusion paper having a surface layer made of water-absorbing fiber is placed between an air electrode and a positive electrode case in order to prevent liquid leakage through air holes provided in the positive electrode case (for example, refer to Patent Literature 2). 
       CITATION LIST 
     Patent Literature 
       [0004]    Patent Literature 1: Japanese Unexamined Patent Application Publication No. 05-013113 
         [0005]    Patent Literature 2: Japanese Unexamined Patent Application Publication No. 06-349529 
       SUMMARY OF INVENTION 
       [0006]    However, in the configurable air cell described in Patent Literature 1, there is a risk of leakage of an electrolysis solution through the ventilation holes because of, for example, damage of the filters, and great pressure loss may be caused since the water-repellent filters are attached to the ventilation holes. In addition, in the air cell described in Patent Literature 2, there is a risk of leakage of an electrolysis solution through the air holes because of, for example, damage of the air diffusion paper, and great pressure loss may be caused since the air diffusion paper is attached to the air holes. 
         [0007]    An object of the present invention is to provide an air cell cartridge and an air cell system capable of preventing leakage of an electrolysis solution and reducing pressure loss. 
         [0008]    An air cell cartridge according to a first aspect of the present invention includes a plurality of air cells each including a positive electrode material, a negative electrode material and an electrolysis solution layer holding an electrolysis solution and interposed between the positive electrode material and the negative electrode material and each being provided with an air flow path through which air passes so as to come into contact with the positive electrode material, the air cells being arranged in a manner such that the air flow path is formed therebetween, wherein a leakage prevention material is provided in the air flow path to absorb the electrolysis solution leaked from the electrolysis solution layer and swell so as to block up the air flow path. 
         [0009]    An air cell system according to a second aspect of the present invention includes an air cell cartridge including a plurality of air cells each including a positive electrode material, a negative electrode material and an electrolysis solution layer holding an electrolysis solution and interposed between the positive electrode material and the negative electrode material and each being provided with an air flow path through which air passes so as to come into contact with the positive electrode material, the air cells being arranged in a manner such that the air flow path is formed therebetween, wherein an air supply pipe connected to the air flow path includes: a leakage prevention material which absorbs the electrolysis solution leaked from the electrolysis solution layer and swells so as to block up the air flow path; a leakage detection sensor which detects leakage of the electrolysis solution from the air cell cartridge; a switching valve which blocks the air flow path; and an air flow blocking means which closes the switching valve to block the air flow path when the leakage detection sensor detects the leakage of the electrolysis solution. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a block diagram showing a schematic configuration of an air cell system according to an embodiment of the present invention. 
           [0011]      FIG. 2  is a perspective view showing part of the air cell system according to the embodiment of the present invention. 
           [0012]      FIG. 3(A)  is a perspective view showing a state of connection between a busbar and air cell cartridges.  FIG. 3(B)  is a perspective view showing a flowing state of air through air cell cartridges connected to a busbar. 
           [0013]      FIG. 4(A)  is a cross-sectional view showing a leakage prevention material in a non-swelling state placed in an air supply pipe.  FIG. 4(B)  is a cross-sectional view showing the leakage prevention material in a swelling state placed in the air supply pipe. 
           [0014]      FIG. 5  is a perspective view of an air cell composing part of an air cell cartridge according to an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0015]    Hereinafter, the present embodiment will be explained with reference to the drawings; however, the scope of the present invention should be defined based on the claims and is not limited only to the embodiment described below. It should be noted that dimensional ratios in the drawings are magnified for convenience of explanation and may be different from actual ratios. 
         [0016]    As shown in  FIG. 1 , an air cell system A according to the embodiment of the present invention includes a plurality of air cell cartridges (hereinafter, simply referred to as “cartridges”) B, a cartridge box C from which the plural cartridges B are removable, and an electrolysis solution tank  5  connected to the cartridge box C via a supply pipe  6 . 
         [0017]    Each of the cartridges B includes a plurality of injection-type air cells  60  arranged therein. It should be noted that, although the air cell  60  is exemplified as an injection-type air cell in the embodiment of the present invention, the air cell  60  is not limited thereto, and various types of cells may be applicable. Although  FIG. 1  shows three cartridges B, the number of the cartridges B is not particularly limited. Further, the number of the air cells  60  included in each cartridge B is not particularly limited. 
         [0018]    The electrolysis solution tank  5  stores an electrolysis solution W to be injected into the air cells  60 . As an example of the electrolysis solution W, an aqueous solution or a non-aqueous solution mainly containing potassium hydroxide (KOH) or chloride, may be used. The supply pipe  6  connected to the electrolysis solution tank  5  is connected to each of the cartridges B installed in the cartridge box C. The supply pipe  6  supplies the electrolysis solution W stored in the electrolysis solution tank  5  to each of the cartridges B. The supply pipe  6  is provided with a switching valve  7 . The switching valve  7  is connected to a control unit D on the output side so that the control unit D operates to open and close the switching valve  7  as appropriate. 
         [0019]    The cartridge box C includes a casing  10  for housing the plural cartridges B, and a busbar  50  installed in the casing  10 . The busbar  50  is connected to connectors  64  of each of the cartridges B. The casing  10  of the cartridge box C is connected with an air supply pipe (hereinafter, also referred to as “an air flow path”)  20  for supplying air to the cartridge box C and connected with an air discharge pipe (hereinafter, also referred to as “an air flow path”)  30  for discharging the air from the cartridge box C. 
         [0020]    The air supply pipe  20  is sequentially provided with, from the side from which the air is introduced into the air cell system A (from the upstream side) to the cartridge box C side (to the downstream side), a filter  21  for removing dust or the like, a blower  22  for sending the air with pressure, a temperature sensor  23 , a pressure detection sensor  24 , a switching valve  25 , and a leakage detection sensor  26 . 
         [0021]    The blower  22  and the switching valve  25  are connected to the control unit D on the output side so as to be driven by the control unit D as appropriate. The temperature sensor  23 , the pressure detection sensor  24  and the leakage detection sensor  26  are connected to the control unit D on the input side. 
         [0022]    The temperature sensor  23  detects the temperature in the air supply pipe  20  and outputs the detected temperature data to the control unit D. The pressure detection sensor  24  detects the pressure in the air supply pipe  20  and outputs the detected pressure data to the control unit D. The leakage detection sensor  26  detects the occurrence of liquid leakage in the air supply pipe  20  and outputs the information of the liquid leakage thus detected to the control unit D. 
         [0023]    The air discharge pipe  30  is sequentially provided with, from the upstream side of the air discharged from the cartridge box C to the downstream side, a leakage detection sensor  31 , a temperature sensor  32 , a pressure detection sensor  33 , and a switching valve  34 . The switching valve  34  is connected to the control unit D on the output side so that the control unit D operates to open and close the switching valve  34  as appropriate. The leakage detection sensor  31 , the temperature sensor  32  and the pressure detection sensor  33  are connected to the control unit D on the input side. 
         [0024]    The leakage detection sensor  31  detects the occurrence of liquid leakage in the air discharge pipe  30  and outputs the information of the liquid leakage thus detected to the control unit D. The temperature sensor  32  detects the temperature in the air discharge pipe  30  and outputs the detected temperature data to the control unit D. The pressure detection sensor  33  detects the pressure in the air discharge pipe  30  and outputs the detected pressure data to the control unit D. 
         [0025]    The switching valve  25  on the upstream side in the air supply pipe  20  and the switching valve  34  on the downstream side in the air discharge pipe  30  are connected to the respective ends of a bypass pipe  40 . In  FIG. 1 , one end of tire bypass pipe  40  is connected to the air supply pipe  20  between the switching valve  25  and the pressure detection sensor  24 . The bypass pipe  40  is provided with a switching valve  41 . The switching valve  41  is connected to the control unit D on the output side so that the control unit D operates to open and close the switching valve  41  as appropriate. Due to the switching valve  41  opened as appropriate, the air introduced into the air cell system A can pass through the bypass pipe  40  towards the discharge side. 
         [0026]    The control unit D includes a central processing unit (CPU), an interface circuit, and the like. The control unit D fulfills the following functions by executing predetermined programs. The control unit D (first air flow blocking means D 1 ) operates to close the switching valve  25  or  34  so as to block the air flow path  20  or  30  when the leakage detection sensor  26  or  31  detects leakage of the electrolysis solution W. Accordingly, the control unit D can stop the operation of the air cells  60 . In addition, the control unit D (second air flow blocking means D 2 ) operates to close the switching valve  25  or  34  so as to block the air flow path  20  or  30  when the pressure detection sensor  24  or  33  detects an increase in pressure in the air flow path  20  or  30 . 
         [0027]    For example, the casing  10  of the cartridge box C has a rectangular parallelepiped as shown in  FIG. 1  and  FIG. 2 . The casing  10  includes a rectangular bottom plate  11 , side plates  12  to  15  vertically extending from the four sides of the bottom plate  11 , and an upper plate  16  placed on the side plates  12  to  15 . 
         [0028]    As shown in  FIG. 2 , the upper plate  16  of the casing  10  is provided with cartridge attachment ports  16   a  to  16   c  at predetermined intervals for attaching and removing the plural cartridges B. The plural cartridges B are inserted into the casing  10  via the cartridge attachment ports  16   a  to  16   c  as indicated by the arrows in  FIG. 2 . 
         [0029]    The side plate  12  of the casing  10  is provided with an introduction port  12   a  located towards the side plate  15  for introducing air into the casing  10 . The side plate  14  of the casing  10  is provided with a discharge port  14   a  located towards the side plate  13  for discharging the air passing through the casing  10 . The introduction port  12   a  and the discharge port  14   a  are connected to the air supply pipe  20  and the air discharge pipe  30 , respectively. 
         [0030]    As shown in  FIG. 1  and  FIG. 3 , the busbar  50  is placed on the bottom plate  11  of the casing  10 . The busbar  50  is electrically connected to the plural cartridges B mounted thereon so as to extract electricity from the cartridges B to the outside thereof. The busbar  50  includes a base  53  on which the plural cartridges B are mounted, connectors  51  projecting from the mounting surface of die base  53  and electrically connected to the plural cartridges B, and partition members  52  for partitioning the plural cartridges B provided on the mounting surface of the base  53 . 
         [0031]    As shown in  FIG. 2 , the introduction port  12   a  and the discharge port  14   a  are respectively located at offset positions on the respective side plates  12  and  14 , so that the air introduced from the introduction port  12   a  passes through the casing  10  while coming into contact with the air cells  60  included in the respective cartridges B mounted on the busbar  50  and is then discharged from the discharge port  14   a,  as shown in  FIG. 3 . 
         [0032]    Here, a leakage prevention material S is placed in the air supply pipe  20  as shown in  FIG. 4(A) . The leakage prevention material S absorbs the electrolysis solution W and swells so as to block up the air supply pipe (the air flow path)  20 . Examples of the leakage prevention material S include a polymer, inorganic salt forming hydrate, and a mixture of the polymer and the inorganic salt. 
         [0033]    The leakage prevention material S is placed, for example, between the switching valve  25  and the leakage detection sensor  26  shown in  FIG. 1 . The leakage detection sensor  26  is preferably located closer to the cartridges B than the leakage prevention material S. In other words, the leakage prevention material S is preferably placed on the upstream side of the leakage detection sensor  26 . The leakage detection sensor  26  located closer to the cartridges B than the leakage prevention material S can detect leakage of the electrolysis solution W immediately and reliably. 
         [0034]    The leakage prevention material S placed does not block up the air supply pipe  20  before absorbing the electrolysis solution W, namely, in a non-swelling state. The way to place the leakage prevention material S is not particularly limited and may be determined, as appropriate. For example, the leakage prevention material S may be placed along the inner circumference of the air supply pipe  20 . Alternatively, the leakage prevention material S may be provided at two points opposite to each other or at three points at even intervals on the inner circumference of the air supply pipe  20 . The leakage prevention material S may also be provided at several points in the longitudinal direction of the air supply pipe  20 . 
         [0035]    The cross-sectional area of the leakage prevention material S in a non-swelling state perpendicular to the longitudinal direction of the air supply pipe  20 , is preferably 1/20 to ½ of the cross-sectional area of the air supply pipe (the air flow path)  20 . When the cross-sectional area of the leakage prevention material S in a non-swelling state is less than or equal to ½ of the cross-sectional area of the air supply pipe  20 , good air supply can be ensured. When the cross-sectional area of the leakage prevention material S in a non-swelling state is greater than or equal to 1/20 of the cross-sectional area of the air supply pipe  20 , the leakage prevention material S in a swelling state can surely block up the air supply pipe  20 . 
         [0036]    When the electrolysis solution W leaks out of the cartridge box C into the air supply pipe  20 , the leakage prevention material S absorbs the electrolysis solution W and swells so as to block up the air supply pipe (the air flow path)  20  as shown in  FIG. 4(B) . As a result, the electrolysis solution W can be prevented from leaking towards the upstream side of the leakage prevention material S. 
         [0037]    The leakage prevention material S may also be placed in the air discharge pipe  30  as in the case of the air supply pipe  20 . The leakage prevention material S is placed, for example, between the leakage detection sensor  31  and the temperature sensor  32  in the air discharge pipe  30 . When the electrolysis solution W leaks out of the cartridge box C into the air discharge pipe  30 , the leakage prevention material S placed in the air discharge pipe  30  absorbs the electrolysis solution W and swells so as to block up the air discharge pipe  30 . As a result, the electrolysis solution W can be prevented from leaking towards the downstream side of the leakage prevention material S. 
         [0038]    Each cartridge B is an assembled battery including the plural air cells  60  as shown in  FIG. 5 . The plural air cells  60  are connected to each other in series or in parallel. It should be noted that  FIG. 5  shows only two air cells  60  for convenience of explanation; however, three or more of the air cells  60  may be connected to each other. Here, for reason of convenience,  FIG. 5  does not show the connectors  64  connected to the busbar  50  that are shown in  FIG. 1 . 
         [0039]    Each of the air cells  60  according to the embodiment of the present invention includes a square frame  61  with the upper surface open and further includes a liquid-tight air-permeable film  62 , a positive electrode layer, an electrolyte layer and a negative electrode layer (each not shown in the figure) which are sequentially stacked from the above in the frame  61 . 
         [0040]    The material usable for the frame  61  may be resin having electrolysis solution resistance such as polypropylene (PP) and engineering plastic. 
         [0041]    The liquid-tight air-permeable film  62  has liquid-tight air-permeability. Namely, the liquid-tight air-permeable film  62  is provided with a plurality of fine pores for supplying gas (air) to the positive electrode layer. At the same time, the liquid-tight air-permeable film  62  has high water repellency so as to prevent the electrolysis solution W from leaking out. The material usable for the liquid-tight air-permeable film  62  may be fluorine resin. 
         [0042]    The positive electrode layer may be made of a porous material including a catalyst and having electric conductivity. The material usable for the negative electrode layer may be pure metal such as lithium (Li), aluminum (Al), iron (Fe), zinc (Zn) or magnesium (Mg), or an alloy thereof. 
         [0043]    The plural air cells  60  are arranged to overlap each other in such a manner as to define an air flow path α therebetween. When power is generated, the air from the air supply pipe  20  is introduced into the cartridge box C. The introduced air flows through the air flow path α between the air cells  60  adjacent to each other as indicated by the arrow in  FIG. 5  to come into contact with the positive electrode layer via the liquid-tight air permeable film  62  in each air cell  60 . 
         [0044]    The frame  61  includes a plurality of partitions  63  extending in parallel to separate the air cells  60  adjacent to each other at a predetermined interval. The air flow path α between the respective air cells  60  is divided into several paths by the partitions  63 . It should be noted that, although the air flow path α is divided into several paths by the partitions  63  in  FIG. 5 , the air flow path α may be a single path as long as the air cells  60  adjacent to each other are separated at a predetermined interval so as to define the air flow path α. 
         [0045]    The leakage prevention material S is placed in the air flow path α on an intake port α 1  side. The leakage prevention material S absorbs the electrolysis solution W leaked out of the air cells  60  and swells so as to block up the intake port α 1 . Accordingly, the electrolysis solution W can be prevented from leaking out of the cartridge B. The cross-sectional area of the leakage prevention material S in a non-swelling state is preferably 1/20 to ½ of the cross-sectional area of the air flow path α as in the case that the leakage prevention material S is placed in the air supply pipe  20 . Here, there are a plurality of intake ports oil defined by the partitions  63  in  FIG. 5  and therefore the leakage prevention material S is provided at each of the intake ports α 1 . 
         [0046]    According to the embodiment of the present invention, the leakage prevention material S is placed in the air flow path a on the intake port α 1  side; however, the leakage prevention material S may be placed on a discharge port α 2  side instead of the intake port α 1  side or may be placed on both the intake port α 1  side and the discharge port α 2  side. 
         [0047]    In the air cell system A according to the embodiment of the present invention, even when the electrolysis solution W leaks from the air cells  60  because of damage or the like, the leakage prevention material S placed in each of the air flow paths  20 ,  30  and α absorbs the leaked electrolysis solution W and swells so as to block up the air flow paths  20 ,  30  and α. As a result, the spread of leakage of the electrolysis solution W can be prevented. Further, since a filter for preventing leakage of the electrolysis solution W is not used in the air flow path  20 ,  30  or α, the pressure loss can be reduced compared with the case where a filter is provided. 
         [0048]    In addition, since the leakage prevention material S swells to block up the air flow paths  20 ,  30  and α, only a small volume is required for preventing leakage of the electrolysis solution W. 
         [0049]    In addition, since the cross-sectional area of the leakage prevention material S in a non-swelling state is 1/20 to ½ of the cross-sectional area of each of the air flow paths  20 ,  30  and α, good air flow can be ensured in the air flow paths  20 ,  30  and α, and the leakage of the electrolysis solution W can be reduced to a minimum. 
         [0050]    In addition, since the leakage prevention material S is placed in the air flow path α on either the intake port α 1  side or the discharge port α 2  side or on both the intake port al side and die discharge port α 2  side adjacent to each other, the leakage of the electrolysis solution W can surely be prevented. Further, the spread of leakage of the electrolysis solution W can surely be prevented even if the leakage of the electrolysis solution W from the injection-type air cells  60  occurs because of an increase in pressure resulting from the injection of the electrolysis solution W therein even though the air cells  60  are not damaged. 
         [0051]    In addition, the plural air cells  60  are connected to each other in series, which contributes to easily increasing the output power. Alternatively, the plural air cells  60  may be connected to each other in parallel so as to keep the operation of power generation even if the electrolysis solution W leaks out. 
         [0052]    In addition, the system A includes the leakage detection sensors  26  and  31  for detecting the leakage of the electrolysis solution W from the cartridges B and the switching valves  25  and  34  for blocking the air flow paths, and further includes the air flow blocking means D 1  which closes the switching valves  25  and  34  to block the air flow paths  20  and  30 . Accordingly, the operation of power generation can surely be stopped when the leakage of the electrolysis solution W is detected. 
         [0053]    In addition, since the leakage detection sensors  26  and  31  are each positioned closer to the cartridge box C than the leakage prevention material S, the leakage can be detected immediately and reliably. 
         [0054]    In addition, the system A includes the air flow blocking means D 2  which closes the switching valves  25  and  34  to block the air flow paths  20  and  30  when an increase in pressure is detected in the air flow paths  20  and  30 . Accordingly, the operation of power generation can surely be stopped when the increase in pressure is caused in association with the leakage of the electrolysis solution W. 
         [0055]    In addition, since the pressure detection sensors  24  and  33  are each positioned closer to the cartridges B than the leakage prevention material S, the leakage can be detected immediately and reliably. 
         [0056]    The present invention is not limited to the embodiment described above and may be applicable to the modified example described below. 
         [0057]    Although the embodiment of the present invention has exemplified the cartridge B including the air cells  60  which are arranged in such a manner as to define the air flow path a therebetween, the air flow path may be formed in other parts other than the region between the air cells  60 . For example, opposed frame members of the frame  61  are provided with intake holes and discharge holes penetrating the frame  61  at a height corresponding to the liquid-tight air-permeable film  62 , so that the liquid-tight air-permeable film  62  located between the intake holes and the discharge holes may serve as the air flow path. 
         [0058]    Although the embodiment of the present invention has exemplified the case that the leakage prevention material S is placed in each of the air cells  60 , the cartridges B and the air cell system A, the leakage prevention material S may be placed in one of the air cells  60 , the cartridges B and the air cell system A. Alternatively, the leakage prevention material S may be placed in two of them. 
         [0059]    Although the embodiment of the present invention has exemplified the case that the leakage prevention material S is placed at the intake ports α 1  or the discharge ports α 2  of the air cells  60 , the leakage prevention material S may be placed adjacent to the positive electrode layer of each air cell  60 . In that case, the leakage of the electrolysis solution W can be reduced to a minimum. 
         [0060]    The entire contents of Japanese Patent Application No. P2012-052418 (filed on Mar. 9, 2012) and Japanese Patent Application No. P2013-03857 (filed on Feb. 28, 2013) are incorporated herein by reference. 
         [0061]    Although the present invention has been described above by reference to the embodiment, the present invention is not limited to the description thereof, and it will be apparent to those skilled in the art that various modifications and improvements can be made. 
       INDUSTRIAL APPLICABILITY 
       [0062]    The present invention can prevent leakage of the electrolysis solution and can be applied to the air cell cartridge and the air cell system capable of reducing pressure loss. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               20 ,  30 , α AIR FLOW PATH 
               24 ,  33  PRESSURE DETECTION SENSOR 
               25 ,  34  SWITCHING VALVE 
               26 ,  31  LEAKAGE DETECTION SENSOR 
               60  AIR CELL 
             B AIR CELL CARTRIDGE 
             D 1  FIRST AIR FLOW BLOCKING MEANS 
             D 2  SECOND AIR FLOW BLOCKING MEANS 
             S LEAKAGE PREVENTION MATERIAL