Abstract:
A base station, includes: an electronic unit; a housing, including a resin, configured to accommodate the electronic unit; a valve, provided in the housing and including a communication channel communicating an inside of the housing with an outside, configured to open the communication channel if an internal pressure of the housing exceeds a value.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2012-122382, filed on May 29, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to a base station. 
     BACKGROUND 
     A base station includes an electronic unit and a housing that is made of metal and accommodates the electronic unit. 
     Related techniques are disclosed in Japanese Laid-open Patent Publication No. 2007-115965, Japanese Unexamined Utility Model Registration Application Publication No. 2-41451, and Japanese Laid-open Patent Publication No. 2003-188569. 
     SUMMARY 
     According to one aspect of the embodiments, an base station, includes: an electronic unit; a housing, including a resin, configured to accommodate the electronic unit; a valve, provided in the housing and including a communication channel communicating an inside of the housing with an outside, configured to open the communication channel if an internal pressure of the housing exceeds a value. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates an exemplary base station; 
         FIGS. 2A through 2F  illustrate an exemplary housing; 
         FIG. 3  illustrates an exemplary perspective view of a housing; 
         FIG. 4  illustrates an exemplary longitudinal sectional view of a base station; 
         FIG. 5  illustrates an exemplary perspective view of a guide member and a valve; 
         FIG. 6  illustrates an exemplary side view of the guide member; 
         FIG. 7  illustrates an exemplary enlarged perspective view of a base station; 
         FIG. 8  illustrates an exemplary valve; 
         FIG. 9  illustrates an exemplary longitudinal sectional view of a base station; 
         FIG. 10  illustrates an exemplary perspective view of a base station; 
         FIG. 11  illustrates an exemplary longitudinal sectional view of a base station; 
         FIG. 12  illustrates an exemplary longitudinal sectional view of a base station; and 
         FIG. 13  illustrates an exemplary longitudinal sectional view of a base station. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Due to wind and rain outdoors, a base station may include an electronic unit that has high protection performance and is accommodated inside a housing. 
       FIG. 1  illustrates an exemplary base station device. An base station  10  (hereinafter, abbreviated as a base station  10 ) includes an electronic unit  20 , a heat sink  30 , a housing  40 , a valve  60 , a guide member  80 , a Peltier element  90 , and a temperature humidity sensor  100 . 
     The electronic unit  20  may include a circuit board  22  that has a plurality of implementation components (not illustrated), such as electronics, implemented therein, and is accommodated in the housing  40 . The heat sink  30  includes a plurality of fins  32  and is coupled to a heat generating component among the implementation components implemented in the circuit board  22 . The heat sink  30  may have an outer shape substantially identical to an outer shape of the housing  40 . A peripheral portion  34  of the heat sink  30  is joined to a flange  44  by a plurality of fastening members  36  in a state of being superimposed on the flange  44  that is formed in a peripheral portion of the housing  40 . 
       FIGS. 2A through 2F  illustrate an exemplary housing. In  FIGS. 2A through 2F , six orthogonal views of the housing  40  are illustrated. For example, the housing  40  may include a resin, such as polycarbonate, and may have a box shape having an opening portion (refer to  FIGS. 2A through 2F ). An opening portion  41  of the housing  40  is covered with the heat sink  30 . The housing  40  is provided with a plurality of, for example four, side wall portions  42 A through  42 D and a bottom wall portion  43  that is surrounded by the side wall portions  42 A through  42 D. 
     On outer surfaces of the side wall portions  42 A,  42 B, and  42 C among the plurality of side wall portions  42 A through  42 D, a plurality of ribs  45  that extend in a thickness direction of the housing  40 , for example, in an arrow T direction, are formed, respectively. On the bottom wall portion  43 , as illustrated in  FIG. 2B , a reinforcing portion  46  in a honeycomb pattern that spreads in a height direction and a transverse width direction of the housing  40 , for example, in an arrow H direction and an arrow W direction, is formed. The base station  10  having the housing  40  is installed outdoors in such a manner that the height direction of the housing  40  agrees with the vertical direction. 
     The side wall portion  42 D (lower wall portion) located in a lower end portion of the housing  40  among the plurality of side wall portions  42 A through  42 D is provided with a plurality of connectors  47  as illustrated in  FIG. 1 . All of the plurality of connectors  47  are electrically coupled to the electronic unit  20 . 
       FIG. 3  illustrates an exemplary perspective view of a housing. In  FIG. 3 , an enlarged perspective view of a main part of the housing is illustrated. In the side wall portion  42 D, as illustrated in  FIG. 3 , an opening portion  48  for maintenance is formed. The opening portion  48  has a rectangular shape in which the transverse width direction of the housing  40  is a longitudinal direction, and is covered with a lid material  49  made of metal. Both between the opening portion  48  for maintenance and the lid material  49  and between the opening portion  41  of the housing  40  and the heat sink  30  may be tightly sealed with a sealing material or the like, not illustrated. 
     In a portion on a side wall portion  42 D side in the bottom wall portion  43 , a pair of notches  50 A and  50 B is formed. The pair of notches  50 A and  50 B may be located in a transverse width direction of the opening portion  48 , for example, on both sides across a central portion in the arrow W direction. In the bottom wall portion  43 , a plurality of auxiliary notches  52 A through  52 E are formed in a portion on a side opposite to the side wall portion  42 D relative to the pair of notches  50 A and  50 B. 
     The plurality of auxiliary notches  52 A through  52 E are formed in alignment in an arrangement direction of the pair of notches  50 A and  50 B, for example, in the arrow W direction, which is the transverse width direction of the housing  40 . Between the pair of notches  50 A and  50 B, a convex portion  54  is formed. The position of the convex portion  54  in the arrangement direction of the pair of notches  50 A and  50 B, for example, in the arrow W direction, may substantially agree with the position of the auxiliary notch  52 C at the center of the plurality of auxiliary notches  52 A through  52 E. 
       FIG. 4  illustrates an exemplary longitudinal sectional view of a base station. As illustrated in  FIG. 4 , the valve  60  may penetrate the side wall portion  42 D (lower wall portion) that is formed in the housing  40 . The valve  60  includes an outer cylinder  61 , a movable member  62 , and a spring  63 . The outer cylinder  61  may be placed in such a manner that an axial direction substantially agrees with the height direction of the housing  40 . An outer peripheral surface of the outer cylinder  61  is provided with an O ring  56 . By the O ring  56 , waterproofness between an inner peripheral surface of a through hole  58  in the side wall portion  42 D that is penetrated by the outer cylinder  61  and the outer peripheral surface of the outer cylinder  61  may be secured. 
     In the outer cylinder  61 , a communication channel  64  that penetrates in the axial direction is formed. The communication channel  64  communicates the inside of the housing  40  with the outside. The opening in the internal side of the housing  40  in the communication channel  64  may be an inlet  65  of the valve  60 . The opening in the external side of the housing  40  in the communication channel  64  may be an outlet  66  of the valve  60 . The outlet  66  of the valve  60  may be directed to a lower side in the height direction (lower side in the vertical direction) of the housing  40 . 
     The movable member  62  may be placed movably in the axial direction of the outer cylinder  61  inside the communication channel  64 . In the central portion of the movable member  62  in the axial direction, an expanded diameter portion  67  that has a diameter smaller than that of the communication channel  64  is formed. The peripheral portion of the inlet  65  is provided with an annular regulating member  68 . One end of the spring  63  is fixed to the regulating member  68 . The other end of the spring  63  is fixed to the expanded diameter portion  67 . The spring  63  gives tension to the expanded diameter portion  67 . The expanded diameter portion  67  is locked in a stopper portion  69  that is formed in the outer cylinder  61  by being pulled by the spring  63 . 
     At a tip end portion of the movable member  62 , a valve portion  70  is formed. In a portion of the communication channel  64  on an outlet  66  side, a valve sheet  71  is formed. The valve sheet  71  is provided with a gasket  72 . In a state that the expanded diameter portion  67  is locked in the stopper portion  69 , the valve portion  70  is closely attached to the gasket  72  and the space between the valve portion  70  and the valve sheet  71  is tightly sealed. For example, the communication channel  64  may be blocked. 
     In a case that an internal pressure of the housing  40  exceeds a prescribed value, the expanded diameter portion  67  is subjected to the internal pressure of the housing  40 . Therefore, the entire movable member  62  including the expanded diameter portion  67  moves against the tension of the spring  63 . As the movable member  62  moves, a gap is created between the valve portion  70  and the valve sheet  71 , and the communication channel  64  is released. The regulating member  68  may be movable in the axial direction of the outer cylinder  61 . By the movement of the regulating member  68 , the tension of the spring  63  or the prescribed value of the internal pressure of the housing  40  to release the communication channel  64  may be altered. 
       FIG. 5  illustrates an exemplary perspective view of a guide member and a valve.  FIG. 6  illustrates an exemplary side view of a guide member. The guide member and the valve illustrated in  FIG. 5  may be the guide member and the valve illustrated in  FIG. 1 . The guide member illustrated in  FIG. 6  may be the guide member illustrated in  FIG. 1 . The guide member  80  is provided inside the housing  40  and is mounted integrally to the valve  60 . The guide member  80  may be placed in such a manner that the height direction agrees with the height direction of the housing  40 . As illustrated in  FIGS. 5 and 6 , the guide member  80  includes a standing wall portion  81  that extends in the height direction and a lower wall portion  82  that is bent from the lower end portion of the standing wall portion  81 , and has an approximate L shape in a side view. In side portions of the guide member  80 , guide walls  83  that protrude to the tip end portion side of the lower wall portion  82  are formed, respectively. The guide walls  83  may be formed from an upper end portion of the standing wall portion  81  over the tip end portion of the lower wall portion  82 . 
     In the lower wall portion  82 , a guide hole  84  that penetrates along the height direction of the guide member  80  is formed. The guide hole  84  may be coupled to, for example, an inlet  65  of the valve  60  illustrated in  FIG. 4 . The lower wall portion  82  is formed on a slant so as to be directed towards an upper side in the height direction of the guide member  80  as getting closer to the tip end portion side. In an upper portion of the standing wall portion  81 , an accommodation portion  85  that penetrates in a plate thickness direction is formed. Hydrophilic treatment or water repellent treatment may also be applied on the guide member  80 . 
     As illustrated in  FIG. 5 , the Peltier element  90  is held by the guide member  80  in a state of being accommodated in the accommodation portion  85 . A cooling surface  91  of the Peltier element  90  may be a low temperature portion and is exposed inside the housing  40 .  FIG. 7  illustrates an exemplary an enlarged perspective view of a base station. The base station illustrated in  FIG. 7  may be the base station illustrated in  FIG. 1 . As illustrated in  FIG. 7 , a heating surface  92  of the Peltier element  90  is coupled to the bottom wall portion  43  of the housing  40 . The heating surface  92  may also be coupled directly to the bottom wall portion  43 , and may also be coupled via a member, such as a thermally conductive adhesive. 
     The temperature humidity sensor  100  illustrated in  FIG. 1  may be provided in the central portion in the height direction inside the housing  40 . A detection signal from the temperature humidity sensor  100  is output to a control portion  102 . The control portion  102  calculates a dew point inside the housing  40  based on the detection signal output from the temperature humidity sensor  100 . The control portion  102  controls the Peltier element  90  in such a manner that the Peltier element  90  becomes lower in temperature than the dew point inside the housing  40 . 
     As the cooling surface  91  illustrated in  FIG. 4  is cooled based on driving of the Peltier element  90 , dew condensation water is produced on the cooling surface  91 . The dew condensation water is guided to the inlet  65  of the valve  60  by the guide member  80 . For example, after falling down the standing wall portion  81  of the guide member  80 , the dew condensation water produced on the cooling surface  91  may be guided through the guide hole  84  to the inlet  65  of the valve  60 . 
     For example, the housing  40  of the base station  10  is provided with the valve  60  that has the communication channel  64  communicating the inside of the housing  40  with the outside. In a case that the internal pressure of the housing  40  exceeds a prescribed value, the valve  60  opens the communication channel  64 . 
     Therefore, even when the internal pressure of the housing  40  increases due to a change in the surrounding environment temperature, in a case that the internal pressure of the housing  40  exceeds the prescribed value, an air inside the housing  40  is discharged to outside. Stress strain of the housing  40  which is made of a resin, based on the change in internal pressure may be reduced, and deformation of the housing  40  may also be reduced. Damage or defects in waterproofness in association with variation in internal pressure of the housing  40  may be reduced to improve the protection performance of the electronic unit  20  that is accommodated inside the housing  40 . 
     On the plurality of side wall portions  42 A through  42 C, the plurality of ribs  45  that extend in the thickness direction of the housing  40 , for example, in the arrow T direction, are formed. By the plurality of ribs  45 , deformation in association with variation in internal pressure of the housing  40  may be reduced. In the bottom wall portion  43 , the reinforcing portion  46  in a honeycomb pattern that spreads in the height direction and the transverse width direction of the housing  40 , for example, in the arrow H direction and the arrow W direction, is formed. By the reinforcing portion  46 , deformation in association with variation in internal pressure of the housing  40 , for example, deformation of the bottom wall portion  43  having a large area may be reduced. 
     The Peltier element  90  is provided inside the housing  40 . The Peltier element  90  may be controlled in such a manner that the cooling surface  91  becomes lower in temperature than the dew point inside the housing  40 . The dew condensation water produced on the cooling surface  91  is guided to the inlet  65  of the valve  60  by the guide member  80 , and is discharged to outside the housing  40  together with an air inside the housing  40  when the communication channel  64  is released. Therefore, in a case that a moisture permeation phenomenon occurs in the housing  40  made of a resin, humidity inside the housing  40  may decrease. Troubles, such as defects in insulation of the electronic unit  20  that is accommodated in the housing  40 , may be reduced. 
     Since the dew condensation water produced on the cooling surface  91  is guided to the inlet  65  of the valve  60  by the guide member  80 , the dew condensation water is smoothly discharged to outside the housing  40 . For example, in the side portions of the guide member  80 , the guide walls  83  that protrude to the tip end portion side of the lower wall portion  82  are formed, respectively. The lower wall portion  82  is formed on a slant so as to be directed towards the upper side in the height direction of the guide member  80  as getting closer to the tip end portion side. Therefore, since the dew condensation water falling down the standing wall portion  81  is smoothly guided to the guide hole  84 , the dew condensation water may be smoothly discharged to outside the housing  40 . 
     In the opened communication channel  64 , an air flows from inside the housing  40  to outside. The outlet  66  of the valve  60  is directed to the lower side in the height direction of the housing  40 , for example, to the lower side in the vertical direction. Therefore, it may be reduced that a foreign substance, a water droplet, and the like enter from the outlet  66  of the valve  60  while the communication channel  64  is opened. In a case that there is no pressure difference between inside and outside the housing  40 , the movable member  62  returns to the home position by the tension of the spring  63 . The valve portion  70  is closely attached with the gasket  72  and the communication channel  64  is blocked. In a case that the internal pressure of the housing  40  is not more than a prescribed value as well, it may be reduced that a foreign substance, a water droplet, and the like enter inside the housing  40 . 
     The heating surface  92  of the Peltier element  90  is coupled to the housing  40 . Therefore, since heat is not easily transferred directly to the electronic unit  20 , heating of the electronics and the like that have implemented in the electronic unit  20  may be reduced. 
     In a portion on the side wall portion  42 D side in the bottom wall portion  43 , the pair of notches  50 A and  50 B is formed. The pair of notches  50 A and  50 B is located on both sides across the central portion in the transverse width direction of the opening portion  48 . Therefore, even when the lid material  49  that covers the opening portion  48  is made of metal having a linear expansion coefficient lower than that of the housing  40  made of a resin, thermal deformation in a surrounding area of the opening portion  48  may be reduced by the pair of notches  50 A and  50 B. Tight sealability between the opening portion  48  for maintenance and the lid material  49  may be secured. 
     For example, in the bottom wall portion  43 , the plurality of auxiliary notches  52 A through  52 E are formed in a portion on a side opposite to the side wall portion  42 D relative to the pair of notches  50 A and  50 B. The position of the convex portion  54  in the arrangement direction of the pair of notches  50 A and  50 B, for example, in the arrow W direction may substantially agree with the position of the auxiliary notch  52 C at the center of the plurality of auxiliary notches  52 A through  52 E. By the plurality of auxiliary notches  52 A through  52 E, the thermal deformation in the surrounding area of the opening portion  48  is reduced. 
       FIG. 8  illustrates an exemplary valve. In the base station  10  illustrated in  FIG. 1 , the Peltier element  90  is held by the guide member  80 . In  FIG. 8 , the Peltier element  90  may be mounted to an inner wall surface of the communication channel  64  on an upstream side than the valve portion  70 . 
     In the base station  10  illustrated in  FIG. 1 , the ribs  45  are formed in the side wall portions  42 A through  42 C among the plurality of side wall portions  42 A through  42 D. As illustrated in  FIG. 8 , the ribs  45  may also be formed in at least one side wall portion among the plurality of side wall portions  42 A through  42 D. 
     The reinforcing portion  46  that is formed in the bottom wall portion  43  may also have a honeycomb pattern that spreads in the height direction and the transverse width direction of the housing  40 , and may also have other patterns, such as a grid pattern or a zigzag pattern that spreads in the height direction and the transverse width direction of the housing  40 . 
     While the Peltier element  90  is used to produce dew condensation water in the base station  10  illustrated in  FIG. 1 , other members may also be used. 
       FIG. 9  illustrates an exemplary longitudinal sectional view of a base station. In  FIG. 9 , a main part of the base station is illustrated. A base station  110  (hereinafter, abbreviated as a base station  110 ) illustrated in  FIG. 9  may have a valve configuration that is different from a configuration of the valve  60  of the base station  10  illustrated in  FIG. 1 . 
     The valve  60  illustrated in  FIG. 9  may be an electromagnetic type and includes a valve main body  122  having an outer cylinder  121 , a valve portion  130 , and an actuator  140 . 
     The outer cylinder  121  is placed in such a manner that an axial direction substantially agrees with the height direction of the housing  40 . An outer peripheral surface of the outer cylinder  121  may be provided with an O ring  56  as illustrated in  FIG. 9 . By the O ring  56 , waterproofness between an inner peripheral surface of a through hole  58  in the side wall portion  42 D that is penetrated by the outer cylinder  121  and the outer peripheral surface of the outer cylinder  121  may be secured. 
     In the outer cylinder  121 , a communication channel  124  that penetrates in the axial direction is formed. The communication channel  124  communicates the inside of the housing  40  with the outside. The opening in the internal side of the housing  40  of the communication channel  124  may be an inlet  125  of the valve  60 . The opening in the external side of the housing  40  in the communication channel  124  may be an outlet  126  of the valve  60 . The outlet  126  of the valve  60  is directed to a lower side in the height direction, for example, the lower side in the vertical direction of the housing  40 . 
     The valve portion  130  is placed movably in a radial direction of the communication channel  124  inside the communication channel  124 . The valve portion  130  is coupled to a movable core  145  of the actuator  140  via a rod  132  and is moved in association with driving of the actuator  140 . The actuator  140  may be an electromagnetic type that includes the movable core  145 , a coil  146 , a case  147 , and a spring  148 , and is coupled to a control portion  142 . To the control portion  142 , a pressure sensor  143  that outputs a signal in accordance with the internal pressure of the housing  40  is coupled. 
     In a position corresponding to the valve portion  130  of the communication channel  124 , a valve sheet  131  is provided. The actuator  140  is driven by the control portion  142 . In a state that the valve portion  130  is advanced by the actuator  140 , the valve portion  130  is closely attached to the valve sheet  131 , and the space between the valve portion  130  and the valve sheet  131  becomes in a state of being tightly sealed. For example, the communication channel  124  is blocked. 
     In a case that the internal pressure of the housing  40  exceeds a prescribed value, the actuator  140  is driven by the control portion  142  and the valve portion  130  retracts. A gap is created between the valve portion  130  and the valve sheet  131  based on the retraction of the valve portion  130 , and the communication channel  124  is released. 
     In a case that the internal pressure of the housing  40  exceeds the prescribed value, an air inside the housing  40  is discharged to outside. Therefore, stress strain of the housing  40  made of a resin due to a change in internal pressure or deformation of the housing  40  may be reduced. Since damage or defects in waterproofness in association with variation in internal pressure of the housing  40  is reduced, the protection performance of the electronic unit  20  that is accommodated inside the housing  40  may also be improved. 
     The Peltier element  90  is mounted to a site on an upstream side than a contact area with the valve sheet  131  of the valve portion  130 . For example, the Peltier element  90  may also be held by the guide member  80  (refer to  FIGS. 1 through 7 ) mounted to the valve  60 . 
       FIG. 10  illustrates an exemplary perspective view of a base station.  FIG. 11  illustrates an exemplary longitudinal sectional view of an base station. In  FIG. 11 , a longitudinal sectional view of a main part of the base station illustrated in  FIG. 10  may be illustrated. 
     In a base station  150  (hereinafter, abbreviated as a base station  150 ) illustrated in  FIGS. 10 and 11 , a spherical metal body  160  is used instead of the Peltier element  90  illustrated in  FIG. 1 . The metal body  160  may include a material having a high thermal conductivity, for example, aluminum, an aluminum alloy, copper, or the like. The metal body  160  is supported by an upper portion  61 A of the outer cylinder  61  via support members  161  and is placed above the valve  60 . 
     In the outer cylinder  61  of the valve  60 , as illustrated in  FIG. 11 , a flange portion  151  and a threaded portion  152  are formed. To the threaded portion  152 , a nut  153  is screwed. Since the side wall portion  42 D is sandwiched by the nut  153  and the flange portion  151 , the valve  60  is fixed to the side wall portion  42 D. 
     The upper portion  61 A of the outer cylinder  61  is inserted inside the housing  40 , and a lower portion  61 B of the outer cylinder  61  is exposed to outside the housing  40 . The upper portion  61 A of the outer cylinder  61  may be a part of the outer cylinder. The lower portion  61 B of the outer cylinder  61  may be another part of the outer cylinder. In  FIG. 11 , a member inside the valve  60 , for example, the valve portion  70 , the valve sheet  71 , and the like illustrated in  FIG. 4  may be omitted. 
     As the metal body  160  becomes lower in temperature than the dew point inside the housing  40 , dew condensation water is produced on a surface of the metal body  160 . In a case that the internal pressure of the housing  40  exceeds a prescribed value, the communication channel  64  of the valve  60  is opened and the dew condensation water is discharged to outside the housing  40  together with an air inside the housing  40 . Therefore, even in a case that a moisture permeation phenomenon occurs in the housing  40  made of a resin, the humidity inside the housing  40  decreases. Troubles, such as defects in insulation of the electronic unit  20  that is accommodated in the housing  40 , may be reduced. 
     Since a simple structure using the metal body  160  is employed, the costs may be reduced. 
     While the metal body  160  is supported by the valve  60  via the support members  161 , it may also be supported by other members, such as the housing  40 , for example. 
     The metal body  160  may also have a spherical shape and may also have other shapes. 
     The valve  60  may also be an electromagnetic type. 
     The outer cylinder  61  of the valve  60 , the metal body  160 , and the support members  161  may include an identical material that has thermal conductivity, for example, aluminum, an aluminum alloy, copper, or the like. Since a part of the outer cylinder  61  is exposed to outside the housing  40 , the heat of an ambient air is introduced by thermal conduction and a continuous difference in temperature may occur in the metal body  160 . 
       FIG. 12  illustrates an exemplary longitudinal sectional view of a base station. 
     In a base station  170  (hereinafter, abbreviated as a base station  170 ) illustrated in  FIG. 12 , the Peltier element  90  is mounted to an inner wall surface of the communication channel  64 . The outer cylinder  61  of the valve  60  may be made of metal. The outer cylinder  61  may include a material having a high thermal conductivity, for example, aluminum, an aluminum alloy, copper, or the like. The upper portion  61 A of the outer cylinder  61  is inserted inside the housing  40 . The lower portion  61 B of the outer cylinder  61  is exposed to outside the housing  40 . An upper end portion and a lower end portion of the outer cylinder  61  are provided with a pair of fins  171  and a pair of fins  172 , respectively. The upper portion  61 A of the outer cylinder  61  may be a part of the outer cylinder. The lower portion  61 B of the outer cylinder  61  may be another part of the outer cylinder. 
     As the lower portion  61 B of the outer cylinder  61  is cooled by an ambient air and the upper portion  61 A of the outer cylinder  61  becomes lower in temperature than the dew point inside the housing  40 , dew condensation water is produced on a surface of the upper portion  61 A of the outer cylinder  61 . The Peltier element  90  is driven to cool the cooling surface  91 . As the cooling surface  91  becomes lower in temperature than the dew point inside the housing  40 , dew condensation water is produced on the cooling surface  91 . In  FIG. 12 , illustration of a member inside the valve  60 , for example, the valve portion  70 , the valve sheet  71 , and the like illustrated in  FIG. 4  may be omitted. 
     In a case that the internal pressure of the housing  40  exceeds a prescribed value, the communication channel  64  of the valve  60  is opened. The dew condensation water is discharged to outside the housing  40  together with an air inside the housing  40 . When a moisture permeation phenomenon occurs in the housing  40  made of a resin, the humidity inside the housing  40  decreases. Therefore, development of troubles, such as defects in insulation of the electronic unit  20  that is accommodated in the housing  40 , may be reduced. 
     Since the outer cylinder  61  of the valve  60  is utilized as a low temperature portion to produce dew condensation water, cost reduction may be achieved. 
     Since the upper end portion of the outer cylinder  61  is provided with the pair of fins  171 , a heat transfer coefficient of the upper portion of the outer cylinder  61  may be improved. Since the lower end portion of the outer cylinder  61  is provided with the pair of fins  172 , the outer cylinder  61  may be cooled. An amount of producing the dew condensation water in the upper portion  61 A of the outer cylinder  61  may increase. 
     The inner wall surface of the communication channel  64  may also be provided with the Peltier element  90  and may also not be provided with it. 
     The valve  60  may be an electromagnetic type. 
       FIG. 13  illustrates an exemplary longitudinal sectional view of a base station. 
     In a base station  180  (hereinafter, abbreviated as a base station  180 ) illustrated in  FIG. 13 , the Peltier element  90  is provided in an upper portion  40 A inside the housing  40 . Inside the housing  40  is provided with a guide portion  190  that guides dew condensation water produced on the cooling surface  91  of the Peltier element  90  to the inlet  65  of the valve  60  that is provided in a lower portion of the housing  40 . The guide portion  190  may be formed integrally with the housing  40  made of a resin and may also be mounted to the housing  40  as a separated body. 
     The Peltier element  90  is provided in the upper portion  40 A inside the housing  40 . Since a warm air rises, the upper portion  40 A inside the housing  40  may be higher in temperature than a lower portion  40 B. Due to a water vapor pressure difference, more dew condensation water may be produced on the cooling surface  91  of the Peltier element  90 . Therefore, the humidity inside the housing  40  may decrease more. The lower portion  40 B inside the housing  40  may be another region. The upper portion  40 A inside the housing  40  may be one example of a region that is higher in temperature than other regions. 
     Between the Peltier element  90  and the valve  60 , the guide portion  190  is provided. By the guide portion  190 , the dew condensation water produced on the cooling surface  91  of the Peltier element  90  is guided to the inlet  65  of the valve  60 . Therefore, the dew condensation water may be smoothly discharged to outside the housing  40 . 
     The Peltier element  90  may be provided in the upper portion  40 A inside the housing  40  and may also be placed in a region that is higher in temperature than other regions inside the housing  40 . The region that is higher in temperature than other regions inside the housing  40  may include, for example, the upper portion  40 A inside the housing  40 , a region for placement of a heat generating component of the electronic unit  20 , or the like. 
     In  FIG. 10  as well, the metal body  160  may also be placed in a region that is higher in temperature than other regions inside the housing  40 . In  FIG. 12  as well, the upper portion  61 A of the outer cylinder  61  may also be placed in a region that is higher in temperature than other regions inside the housing  40 . 
     The valve  60  may be an electromagnetic type. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.