Patent Publication Number: US-2021164672-A1

Title: Work hood

Description:
TECHNICAL FIELD 
     The present invention relates to a work hood used in environments requiring high air cleanliness for separating a worker from the environment. 
     BACKGROUND ART 
     In a work at a manufacturing or research and development stage of pharmaceutical products, environments requiring high air cleanliness such as a clean room and a dust-free room must be prepared. Specifically, workers often fill such pharmaceutical products into a sterile container manually, and potential work environment contamination is prevented by employing a work box operated in a sterile/dust-free state. Conversely, works for handling materials harmful to the human body and the like involve the use of work boxes sealed in operation to protect a worker from a contaminated environment. What is employed in these work boxes for a worker to perform a work is a glove box system using a glove from an outside of the work box or a work hood system using a work hood such as a half suit with the upper body projecting into the work box. 
     In the glove box system, a wall portion partially composed of a work box is formed of a transparent glass panel, and a worker can perform a work in the work box through a glove held at the transparent wall portion, while visually confirming the inside of the work box from the outside thereof through the transparent wall portion. Nonetheless, the glove box system provides a limited work area, and its fixed glove position restricts the movement of worker&#39;s arms, resulting in insufficient workability. 
     Meanwhile, the work hood system composed of a half suit requires a worker to wear a half suit from the outside of the work box. The worker in the half suit can perform a work with the upper body projecting into the work box, leading to more improved workability than the glove box system. 
     Illustrative example of the work box for a worker in the half suit to perform a work includes the one proposed in the following patent document 1: an aseptic filling/packaging apparatus including a half suit made of an air-impermeable and flexible material such that the half suit projects into the inside of an aseptic chamber. 
     Herein, the above half suit, formed of flexible materials such as rubber materials and vinyl chloride resins, provides a significantly improved workability compared to the glove box system. While a work hood formed of any of these flexible materials shows some degree of freedom for a worker to tilt the body forward/backward rightward/leftward, the degree of freedom for body rotation is low and thus further improvement in operating efficiency has been required. 
     For instance, the following patent document 2 proposes a work hood capable of freely and entirely rotating a half suit in a work box. The work hood is used primarily for manually sorting low-level radioactive waste at nuclear power plants. Thus, a sealing member is disposed at the boundary between a rotary half suit and the work hood to protect a worker from contaminants in the work box. 
     CITATION LIST 
     Patent Literature 
     Patent Document 1: JP-A-11-208623 A 
     Patent Document 2: JP-A-2001-074883 A 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     Meanwhile, in a work box (mainly an isolator) used in works for filling pharmaceutical products into a sterile container, the inside thereof needs frequent decontamination for sterilization or dust removal to strictly maintain an internal sterile/dust-free environment. Unfortunately, in ordinary decontamination works, a contact portion of a sealing member present at the boundary between a half suit and a work box (a contact portion between a rotary half suit and a bottom wall portion of a work box) can not sufficiently be decontaminated. For this reason, rotary half suits have not traditionally been employed in work boxes in a sterile environment. 
     The present invention was made in view of the situation to solve the problems, and has an object to provide a work hood that allows for free rotation in a work box to provide a wide work area and easy decontamination of a sealing portion at the boundary between the work hood and the work box. 
     Solution to the Problem 
     To solve the aforementioned problem, inventors of the present invention have carried out an extended investigation to find a technique of providing a small space on the external environmental side of a sealing member present at the boundary between a half suit and a work box (on the side of the worker&#39;s lower body opposite the work box), and using the small space, a decontamination gas is both discharged to the sealing member and sucked. Based on that technique, the inventors found that the cleanliness of the sealing member can sufficiently be maintained and the object of the present invention can be fulfilled, and the present invention was accomplished. 
     Specifically, a work hood according to the present invention is, according to description in claim  1 , a work hood ( 20 ,  120 ,  220 ,  320 ) including a hollow half suit ( 21 ,  121 ,  221 ,  321 ), the work hood being connected around an opening ( 13   a ) formed at part of a work box ( 12 ) and projecting into the inside of the work box, characterized in that 
     a connecting portion between the periphery of the opening and a hem portion ( 21   a,    121   a,    221   a,    321   a ) of the half suit is provided with an annular rotation support ( 30 ,  130 ,  230 ,  330 ) for rotatably supporting the entire half suit, 
     the rotation support includes a base portion ( 31 ,  131 ,  231 ,  331 ), a rotating portion ( 32 ,  132 ,  232 ,  332 ), a bearing portion ( 33 ,  133 ,  233 ,  333 ), a sealing member ( 34 ,  134 ,  234 ,  334 ), and a communication hole ( 35 ,  135 ,  235 ,  335 ), 
     the base portion is airtightly and annularly provided around the opening, 
     the rotating portion is rotatably and annularly provided so as to airtightly fix the hem portion of the half suit over the whole periphery and be opposite the base portion through the bearing portion around the base portion, 
     the sealing member is annularly provided over the whole periphery of the rotation support in an annular gap ( 38 ,  138 ,  238 ,  338 ) formed by the base portion and the rotating portion so as to separate the work box and the external environment, 
     the communication hole is provided in an annular small space ( 39 ,  139 ,  239 ,  339 ) formed by the sealing member together with the base portion, the rotating portion, and the bearing portion so as to lead to the external environmental side from the small space side, and 
     a supply means ( 41 ) for supplying clean air, a decontamination gas or a decontamination mist to the inside of the small space and/or a suction means ( 42 ) for sucking clean air, a decontamination gas or a decontamination mist from the inside of the small space are connected to the opening of the communication hole. 
     Moreover, the present invention is, according to description in claim  2 , the work hood according to claim  1 , characterized in that 
     the bearing portion includes a large bearing having an outer diameter corresponding to the periphery of the opening, and 
     the rotating portion is rotated opposite the base portion by fixing an inner race ( 33   a,    133   a,    233   a ) of the bearing to the outer periphery of the base portion and an outer race ( 33   b,    133   b,    233   b ) of the bearing to the inner periphery of the rotating portion such that a rotating shaft of the large bearing is orthogonal to an opening surface of the opening. 
     Furthermore, the present invention is, according to description in claim  3 , the work hood according to claim  1 , characterized in that 
     the bearing portion includes a plurality of small bearings ( 333   a ), 
     the plurality of small bearings is annularly arranged over the outer periphery of the base portion and the respective shaft portions ( 333   c ) are provided toward the center of the ring, and 
     the rotating portion is rotated opposite the base portion by allowing the annular periphery of the rotating portion to come into contact with the outer race ( 333   b ) of each of the small bearings. 
     Moreover, the present invention is, according to description in claim  4 , the work hood according to any one of claims  1  to  3 , characterized in that 
     the sealing member ( 434 ) is projected onto either of wall surfaces ( 431   c,    432   c ) of the base portion and the rotating portion forming the annular gap, and includes control mechanisms ( 434   a,    434   b,    434   c ) for changing the height of a projecting portion of the sealing member, and 
     the control mechanisms are activated to allow a projection end of the sealing member to move such that the projection end comes into contact with the wall surface of the rotating portion or the base portion in opposition thereto. 
     Furthermore, the present invention is, according to description in claim  5 , the work hood according to any one of claims  1  to  4 , including 
     a drive unit ( 50 ) for rotating opposite the base portion the rotating portion fixing the half suit, the drive unit including:
         a stationary disk portion ( 51 ) having a diameter engageable on the annular inner periphery of the base portion;   a rotary disk portion ( 52 ) having a diameter engageable on the annular inner periphery of the rotating portion;   a support shaft portion ( 53 ) passing through the central axis with the stationary disk portion and the rotary disk portion;   a drive portion ( 54 ) for rotating the rotary disk portion opposite the stationary disk portion concentrically; and   a compressed air supply portion ( 55 ) for expanding the half suit, characterized in that   the stationary disk portion includes a first annular expansion packing ( 51   b ) on the outer periphery of the base portion such that the discoid outer periphery comes into contact with the annular inner periphery of the base portion to be fixed,   the rotary disk portion includes a second annular expansion packing ( 52   b ) on the outer periphery of the rotating portion such that the discoid outer periphery comes into contact with the annular inner periphery of the rotating portion to be fixed,   the support shaft portion is composed of double pipes, with a first pipe ( 53   a ) supporting the stationary disk portion and a second pipe supporting the rotary disk portion, and the second pipe ( 53   b ) operated with the drive portion to rotate the rotary disk portion, and   the compressed air supply portion supplies compressed air to the inside of the half suit hermetically sealed by the rotating portion and the rotary disk portion through a supply pipe ( 55   a ) passing through the support shaft portion from a compressed air supply source in the external environment.       

     Advantageous Effects of the Invention 
     According to the above configuration, the work hood according to the present invention is provided with an annular rotation support at a connecting portion between the periphery of an opening formed at part of a work box and a hem portion of a half suit. The rotation support includes a base portion, a rotating portion, a bearing portion, a sealing member, and a communication hole. The base portion is airtightly and annularly provided around the opening. Meanwhile, the rotating portion is rotatably and annularly provided through the bearing portion around the base portion. Also, in the rotating portion, the hem portion of the half suit is airtightly fixed over the whole periphery. These configurations allow the rotation support to rotatably support the entire half suit, resulting in a wider work area for a worker in the half suit. 
     The sealing member is annularly provided over the whole periphery of the rotation support in an annular gap formed by the base portion and the rotating portion so as to separate the work box and the external environment. The communication hole is provided in an annular small space formed by the sealing member together with the base portion, the rotating portion, and the bearing portion so as to lead to the external environmental side from the small space side. A supply means for supplying clean air, a decontamination gas or a decontamination mist to the inside of the small space can be connected to the opening of the communication hole. Accordingly, in decontamination works, while a decontamination gas or a decontamination mist can be supplied not only to a work box, but also to a small space to achieve decontamination of the sealing member both from the work box side and the external environmental side. Therefore, the sealing member present at the boundary between the work hood and the work box can readily and completely be decontaminated. 
     Also, to the opening of the communication hole can be connected a suction means for sucking clean air, a decontamination gas or a decontamination mist from the inside of the small space. Accordingly, in decontamination works, a decontamination gas or a decontamination mist can readily be removed or aerated. Therefore, the sealing member present at the boundary between the work hood and the work box can readily and completely be decontaminated. Furthermore, even when the work box is operated in a sterile state, the suction means can always suck clean air in the work box through the sealing member and the small space, thereby favorably maintaining clean environment inside the work box. 
     Moreover, according to the above configuration, the bearing portion of the rotation support may include a large bearing having a diameter corresponding to the periphery of the opening. In this case, an inner race of the bearing is fixed to the outer periphery of the base portion and the outer race of the bearing is fixed to inner periphery of the rotating portion such that a rotating shaft of the large bearing is orthogonal to an opening surface of the opening. Accordingly, the rotating portion can be rotated opposite the base portion. Therefore, the rotation support can rotatably support the entire half suit, resulting in a wider work area for a worker in the half suit. 
     Additionally, according to the above configuration, the bearing portion of the rotation support may include a plurality of small bearings. In this case, the plurality of small bearings is annularly arranged over the outer periphery of the base portion, the respective shaft portions are provided toward the center of the ring, and the annular periphery of the rotating portion comes into contact with the outer race of each of the small bearings. Accordingly, the rotating portion can be rotated opposite the base portion. Therefore, the rotation support can rotatably support the entire half suit, resulting in a wider work area for a worker in the half suit. 
     Moreover, according to the above configuration, the sealing member provided in an annular gap formed by the base portion and the rotating portion is projected onto either of wall surfaces of the base portion and the rotating portion. The sealing member may include control mechanisms for changing the height of a projecting portion of the sealing member. The control mechanisms are activated to allow a projection end of the sealing member to move such that the projection end comes into contact with the wall surface of the rotating portion or the base portion in opposition thereto by changing the height of the sealing member. 
     In cases where the projection end of the sealing member comes into contact with the wall surface in opposition thereto, the annular gap formed by the base portion and the rotating portion can airtightly be separated into the work box side and the external environmental side. Accordingly, the clean environment inside the work box can favorably be maintained. Meanwhile, in cases where the gap is slightly left without allowing the projection end of the sealing member to come into contact with the wall surface in opposition thereto, the rotating portion can readily be rotated opposite the base portion, and the sealing member present at the boundary between the work hood and the work box can readily and completely be decontaminated. 
     In addition, according to the above configuration, the work hood according to the present invention may include a drive unit for rotating opposite the base portion the rotating portion fixing the half suit. The drive unit includes a stationary disk portion, a rotary disk portion, a support shaft portion, a drive portion, and a compressed air supply portion. The stationary disk portion has a diameter engageable on the annular inner periphery of the base portion, and includes a first annular expansion packing on the outer periphery of the base portion such that the discoid outer periphery comes into contact with the annular inner periphery of the base portion to be fixed. The rotary disk portion has a diameter engageable on the annular inner periphery of the rotating portion, and includes a second annular expansion packing on the outer periphery of the rotating portion such that the discoid outer periphery comes into contact with the annular inner periphery of the rotating portion to be fixed. 
     The support shaft portion is composed of double pipes passing through the central axis of the stationary disk portion and the rotary disk portion, with a first pipe supporting the stationary disk portion and a second pipe supporting the rotary disk portion. Also, the second pipe is operated with the drive portion to rotate the rotary disk portion opposite the stationary disk portion coaxially. The compressed air supply portion supplies compressed air to the inside of the half suit hermetically sealed by the rotating portion and the rotary disk portion through a supply pipe passing through the support shaft portion from a compressed air supply source in the external environment to expand the half suit. 
     Accordingly, in decontamination works, clean air, a decontamination gas or a decontamination mist can thoroughly be delivered to an annular small space formed by the sealing member together with the base portion, the rotating portion, and the bearing portion. Also, the sealing member present at the boundary between the work hood and the work box can be decontaminated in rotation. Therefore, the sealing member can readily and completely be decontaminated. 
     The reference letters in parenthesis for each of the above means correspond to the specific means described in each of the following embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view showing an isolator including a work hood viewed from the front; 
         FIG. 2  is a schematic cross-sectional view (taken along the line A-A of  FIG. 1 ) showing the isolator in  FIG. 1  viewed from the top; 
         FIG. 3  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in a work hood in a first embodiment; 
         FIG. 4  is a schematic cross-sectional view showing the rotation support of the work hood operated in s sterile environment viewed from the front; 
         FIG. 5  is a schematic cross-sectional view showing the rotation support of the work hood during a decontamination work viewed from the front; 
         FIG. 6  is a schematic cross-sectional view showing a rotation support of a work hood during a decontamination work that is different from that in  FIG. 5  viewed from the front; 
         FIG. 7  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of the rotation support included in the work hood; 
         FIG. 8  is a schematic cross-sectional view showing the relationship between a small space and a communication hole in a second embodiment viewed from the top; 
         FIG. 9  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in a work hood in a third embodiment; 
         FIG. 10  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in a work hood in a fourth embodiment; 
         FIG. 11  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in a work hood in a fifth embodiment; and 
         FIG. 12  is a schematic cross-sectional view showing a rotation support of a work hood including a drive unit in a sixth embodiment viewed from the front. 
     
    
    
     DETAILED DESCRIPTION 
     A work hood according to the present invention will be described with reference to each embodiment. The present invention is not restricted to each of the following embodiments. 
     First Embodiment 
     A first embodiment of the work hood according to the present invention will be described with reference to the drawings.  FIG. 1  is a schematic cross-sectional view showing an isolator including a work hood viewed from the front.  FIG. 2  is a schematic cross-sectional view (taken along the line A-A of  FIG. 1 ) showing the isolator viewed from the top. In  FIGS. 1 and 2 , an isolator  10  is composed of leg portions  11  placed on the floor, a work box (chamber)  12  placed on the leg portions  11 , and a work hood  20  including a hollow half suit  21  connected at an circular opening  13   a  formed at a bottom wall portion  13  inside the chamber  12  and projecting into the inside of the chamber  12 . In  FIG. 2 , the work hood  20  is rotatable horizontally at any angle including 360°. 
     Subsequently, the configuration of a rotation support for allowing the work hood to rotate will be described.  FIG. 3  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in the work hood  20 . In  FIG. 3 , the work hood  20  is connected around the circular opening  13   a  formed at the bottom wall portion  13  inside the chamber  12  by an annular rotation support  30 . The rotation support  30  includes a base portion  31 , a rotating portion  32 , a bearing portion  33 , a sealing member  34 , and a communication hole  35 . 
     The base portion  31  is an annular structure including an L-shaped section composed of a cylindrical portion  31   a  and an annular plate portion  31   b  projecting into the outside in the normal direction from an end of the cylindrical portion. The annular plate portion  31   b  is circular on the inner periphery and airtightly fixed to the bottom wall portion  13  of the chamber  12  with bolts  36   a  over the whole periphery such that the inner periphery of the annular plate portion overlaps the inner periphery of the circular opening  13   a  of the chamber  12 . The inner periphery portion of the cylindrical portion  31   a  forms an opening of the work hood  20  into which a worker inserts the upper body. Meanwhile, an inner race  33   a  of the bearing portion  33  is fixed to the outer periphery of the cylindrical portion  31   a.  In the first embodiment, a large ball bearing constitutes the bearing portion  33 . 
     The rotating portion  32  is an annular structure including an inverted L-shaped section composed of a cylindrical portion  32   a  and an annular plate portion  32   b  projecting into the inside in the normal direction from an end of the cylindrical portion. The cylindrical portion  32   a  is placed outside the cylindrical portion  31   a  of the base portion  31  so as to be coaxial therewith, and an outer race  33   b  of the bearing portion  33  is fixed to the inner periphery of the cylindrical portion  32   a.  Meanwhile, the annular plate portion  32   b  is circular on the inner periphery and airtightly fixed to an upper surface of the cylindrical portion  32   a  with a bolt  36   b  over the whole periphery such that the inner periphery of the annular plate portion overlaps the inner periphery of the cylindrical portion  31   a  of the base portion  31 . A base end portion  21   a  of the half suit  21  (see  FIG. 1 ) formed of a flexible material is airtightly fixed to an outer peripheral side surface of the rotating portion  32  (an outer peripheral side surface of the rotating portion  32 ) configured by the cylindrical portion  32   a  and the annular plate portion  32   b  by two O-rings  22 . 
     Thus, in this first embodiment, the base portion  31  and the rotating portion  32  of the rotation support  30  are fixed through the bearing portion  33  (a large ball bearing). Accordingly, in the rotation support  30 , the rotating portion  32  fixing the half suit  21  can be rotatable at any angle including 360° opposite the base portion  31  fixed to the bottom wall portion  13  of the chamber  12 . 
     Herein, the large ball bearing that constitutes the bearing portion  33  may be airtight or non-airtight. In cases where a non-airtight large ball bearing is used, a packing may be used in an annular gap  37  (see  FIG. 3 ) between the cylindrical portion  31   a  of the base portion  31  and the annular plate portion  32   b  of the rotating portion  32 . In this first embodiment, the bearing portion  33  used is an airtight large ball bearing. 
     The sealing member (lip seal)  34  is annularly projected on a lower end surface  32   c  of the cylindrical portion  32   a  in an annular gap  38  formed by the lower end surface  32   c  of the cylindrical portion  32   a  of the rotating portion  32  and the upper surface  31   c  of the annular plate portion  31   b  of the base portion  31 . The lip seal  34  is formed of an elastic body such as synthetic rubber. The tip of the lip seal  34  may slightly come into contact with the upper surface  31   c  of the annular plate portion  31   b,  and more preferably, may have a slight gap. Accordingly, a decontamination gas is readily supplied to the tip of the lip seal  34 , thereby ensuring a decontamination effect at the sealing portion. 
     In  FIG. 3 , the lip seal  34  forms an annular small space  39  surrounded by the base portion  31 , the rotating  32 , and the bearing portion  33  (large ball bearing). A communication hole  35  for leading to the external environment is provided from the small space  39 . As to the communication hole  35 , only one hole may be provided through the small space  39 , or a plurality thereof may be provided annularly. The direction of the small space  39  formed may be any direction such as the vertical or horizontal direction as long as the space leads to the external environment. In this first embodiment, one communication hole  35  is provided in the vertical direction. The communication hole  35  is connected to a decontamination gas supply unit, a compressed air supply unit, and a vacuum suction unit disposed in the external environment through pipes (see below). 
     Herein, works in a sterile environment inside the chamber  12  and decontamination works will be described. In this first embodiment, the rotatable work hood  20  is disposed inside the chamber  12 . Consequently, the configuration of the rotating portion of the work hood  20 , particularly the lip seal  34  and the small space  39  are complicated in stricture, thereby requiring regular cleaning and accurate decontamination at these portions. 
     First, works in a sterile environment will be described.  FIG. 4  is a schematic cross-sectional view showing the rotation support of the work hood operated in s sterile environment viewed from the front. In  FIG. 4 , the inside of the decontaminated chamber  12  is maintained at positive pressure compared to the external environment. In  FIG. 4 , the positive pressure is denoted by a symbol (+). A clean air supply unit to the inside of the chamber  12  and a positive pressure control apparatus are not shown. 
     In addition, a decontamination gas supply unit  41  and a depressurizing suction device  42  are connected to an opening on the external environmental side of the communication hole  35  via a pipe  43 . The pipe  43  is provided with a three-way valve  44  for shifting the communication between the decontamination gas supply unit  41  and the depressurizing suction device  42 . In this first embodiment, the decontamination gas used is a hydrogen peroxide gas. A HEPA filter  45  and a catalytic device  46  for decomposing hydrogen peroxide are provided between the depressurizing suction device  42  and the three-way valve  44  in the pipe  43 . 
     The effect of the communication hole  35  thus piped will be described. During the operation in a sterile environment, the three-way valve  44  is shifted to communicate the communication hole  35  and the depressurizing suction device  42  through the pipe  43 . By operating the depressurizing suction device  42 , the clean air inside the chamber  12  passes through the gap between the base portion  31  and the rotating portion  32  of the rotation support  30  to be sucked from the pipe  43  to the depressurizing suction device  42  through a gap of the lip seal  34  and the small space  39  (the direction indicated by an arrow). Meanwhile, the positive pressure inside the chamber  12  is controlled by a clean air supply unit and a positive pressure control apparatus (both not shown). Accordingly, even when a worker (not shown) performs a work by rotating the work hood  20 , the sterile environment inside the chamber  12  is maintained. 
     Subsequently, decontamination works will be described.  FIG. 5  is a schematic cross-sectional view showing the rotation support of the work hood during a decontamination work viewed from the front. In  FIG. 5 , a decontamination gas (hydrogen peroxide gas) is supplied to the inside of the chamber  12 . In  FIG. 5 , a decontamination gas is denoted by a symbol (H 2 O 2 ). A decontamination gas supply unit to the inside of the chamber  12  and a decontamination gas concentration control apparatus are not shown. To the opening on the external environmental side of the communication hole  35  are connected the above decontamination gas supply unit  41 , the depressurizing suction device  42 , the pipe  43 , the three-way valve  44 , the HEPA filter  45 , and the catalytic device  46 . 
     The effect of the communication hole  35  thus piped will be described. During a decontamination work, the three-way valve  44  is switched to communicate the communication hole  35  and the depressurizing supply unit  41  through the pipe  43 . By operating the depressurizing supply unit  41 , a decontamination gas (H 2 O 2 ) is supplied to the small space  39  and the lip seal  34  from the pipe  43  and the communication hole  35 , and passes through a gap between the base portion  31  and the rotating portion  32  of the rotation support  30  through the gap of the lip seal  34  to be introduced to the inside of the chamber  12  (the direction indicated by an arrow). In this first embodiment, the supply pressure in the depressurizing supply unit  41  is controlled so as to be higher than the internal pressure of the chamber  12 . 
     During an aeration after a decontamination work by the decontamination gas (H 2 O 2 ), the decontamination gas (H 2 O 2 ) inside the chamber  12  is removed and the gas is normalized using clean air by the depressurizing suction device  42  through the same route as the above positive pressure control. In this case, the decontamination gas (H 2 O 2 ) sucked is decomposed by the catalytic device  46  in the pipe. Accordingly, the lip seal  34  complicated in structure and the small space  39  are decontaminated with high precision. During an aeration, rather than sucking clean air inside the chamber  12  by the depressurizing suction device  42 , the depressurizing supply unit  41  may be replaced with a clean compressed air supply unit (not shown) to supply clean air to the inside of the chamber  12  through the same route as the decontamination work. 
     Then, a decontamination work different from the above decontamination work will be described.  FIG. 6  is a schematic cross-sectional view showing a rotation support of a work hood during a decontamination work that is different from that in  FIG. 5  viewed from the front. In  FIG. 6 , a decontamination gas (hydrogen peroxide gas) is supplied to the inside of the chamber  12 . In  FIG. 6 , a decontamination gas is denoted by a symbol (H 2 O 2 ). A decontamination gas supply unit to the chamber  12  and a decontamination gas concentration control apparatus are not shown. To the opening on the external environmental side of the communication hole  35  are connected the above decontamination gas supply unit  41 , the depressurizing suction device  42 , the pipe  43 , the three-way valve  44 , the HEPA filter  45 , and the catalytic device  46 . 
     The effect of the communication hole  35  thus piped will be described. During a decontamination work, the three-way valve  44  is switched to communicate the communication hole  35  and the depressurizing suction device  42  through the pipe  43 . By operating the depressurizing suction device  42 , a decontamination gas (H 2 O 2 ) inside the chamber  12  passes through a gap between the base portion  31  and the rotating portion  32  of the rotation support  30  to be sucked to the depressurizing suction device  42  from the pipe  43  through the gap at the lip seal  34  and the small spaces  39  (the direction indicated by an arrow). Meanwhile, the concentration of the decontamination gas (H 2 O 2 ) inside the chamber  12  is controlled by a decontamination gas supply unit and a decontamination gas concentration control unit (both are not shown). 
     Herein, the sucked decontamination gas (H 2 O 2 ) is decomposed by the catalytic device  46  in the pipe. During an aeration after a decontamination work by the decontamination gas (H 2 O 2 ), the decontamination gas (H 2 O 2 ) inside the chamber  12  is removed and the gas is normalized using clean air by the depressurizing suction device  42  through the same route as the decontamination work. In this case, the decontamination gas (H 2 O 2 ) sucked by the catalytic device  46  in the pipe is also decomposed. Accordingly, the lip seal  34  complicated in structure and the small space  39  are decontaminated with high precision. 
     Second Embodiment 
     A second embodiment of the work hood according to the present invention will be described with reference to the drawings. In this second embodiment, the position and number of communications holes leading to the external environment from a small space are different from those in the first embodiment.  FIG. 7  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in the work hood.  FIG. 8  is a schematic cross-sectional view showing the relationship between a small space and a communication hole in the second embodiment viewed from the top. 
     In  FIG. 7 , a work hood  120  is connected around a circular opening  13   a  formed at a bottom wall portion  13  inside a chamber  12  by an annular rotation support  130 . The rotation support  130  includes a base portion  131 , a rotation portion  132 , a bearing portion  133 , a lip seal  134 , and a communication hole  135 . The configurations of the base portion  131 , the rotation portion  132 , the bearing portion  133 , and the lip seal  134  are identical to those in the above first embodiment. 
     In  FIGS. 7 and 8 , the lip seal  134  forms an annular small space  139  surrounded by the base portion  131 , the rotation portion  132 , and the bearing portion  133  (large ball bearing). The small space  139  is provided with the communication hole  135  leading to the external environment. In this second embodiment, 4 communication holes  135  equally spaced in the annular small space  139  are provided horizontally. Each of the 4 communication holes  135  has a predetermined angle from the annular central direction of the small space  139  (see  FIG. 8 ). The 4 communication holes are each connected to a decontamination gas supply unit, a compressed air supply unit, and a vacuum suction unit disposed in the external environment through a pipe. In this second embodiment, works in a sterile environment inside the chamber  12  and decontamination works are performed in the same manner as in the above first embodiment. 
     Herein, the reason for providing 4 communications holes  135  horizontally and then providing the same at a predetermined angle from the annular central direction of the small space  139  will be described. In a decontamination work, a decontamination gas (H 2 O 2 ) flowing into the small space  139  from the 4 communication holes  135  runs in a constant direction inside the small space  139  (clockwise in  FIG. 8 ). Thus, the decontamination gas flowing into the small space  139  contacts each of the walls of the small space  139  in flow and is introduced to the inside of the chamber  12  through the lip seal  134 . Accordingly, the lip seal  134  complicated in structure and the small space  139  are decontaminated with higher precision. 
     A cylindrical portion  132   a  of a rotating portion  132  that constitutes the small space  139  may be provided with a plurality of resistance plates (not shown in  FIG. 8 ). By allowing the decontamination gas flowing in a constant direction to hit the small space  139  from the 4 communication holes  135 , the rotating portion  132  of the rotation support  130  is slightly rotated opposite the base portion  131 . Accordingly, the lip seal  134  complicated in structure and the small space  139  are decontaminated with much higher precision. 
     Third Embodiment 
     A third embodiment of the work hood according to the present invention will be described with reference to the drawings. In this third embodiment, the configuration of a rotating portion of a rotation support is different from that in the above first embodiment.  FIG. 9  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in the work hood in the third embodiment. 
     In  FIG. 9 , a work hood  220  is connected around a circular opening  13   a  formed at a bottom wall portion  13  inside a chamber  12  by an annular rotation support  230 . The rotation support  230  includes a base portion  231 , a rotation portion  232 , a bearing portion  233 , a lip seal  234 , and a communication hole  235 . The configurations of the base portion  231 , the bearing portion  233 , the lip seal  234 , and the communication  235  are identical to those in the above first embodiment. 
     In  FIG. 9 , the rotating portion  232  is an L-shaped annular structure composed of a circular portion  232   a  and an annular plate portion  232   b  projecting upward in the cylindrical axis direction from the outer peripheral end. The circular portion  232   a  is disposed outside a cylindrical portion  231   a  of the base portion  231  so as to be coaxial therewith, and an outer race  233   b  of the bearing portion  233  is fixed to the inner periphery. Meanwhile, the annular plate portion  232   b  is cylindrical on the outer periphery, and is airtightly fixed to an upper surface of the cylindrical portion  232   a  with a bolt  236   b  over the whole periphery so as to overlap the outer periphery of the cylindrical portion  232   a.  Also, two flat bands  223  are airtightly fixed to inner and outer surfaces of a base end portion  221   a  of a half suit  221  formed of a flexible material on an outer peripheral side surface of a circular plate portion  232   b.    
     Thus, in this third embodiment, the base portion  231  and the rotating portion  232  of the rotation support  230  are fixed through the bearing portion  233  (large ball bearing). Accordingly, in the rotation support  230 , the rotating portion  232  fixing the half suit  221  can be rotatable at any angle including 360° opposite the base portion  231  fixed to the bottom wall portion  13  of the chamber  12 . 
     The communication hole  235  is connected to a decontamination gas supply unit, a compressed air supply unit, and a vacuum suction unit disposed in the external environment through a pipe. In this third embodiment, works in a sterile environment inside the chamber  12  and decontamination works are performed in the same manner as in the above first embodiment. Accordingly, the lip seal  234  complicated in structure and a small space  239  are decontaminated with high precision. 
     Fourth Embodiment 
     A fourth embodiment of the work hood according to the present invention will be described with reference to the drawings. In this fourth embodiment, the configuration of the bearing portion is different from that in the above third embodiment.  FIG. 10  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in the work hood in the fourth embodiment. 
     In  FIG. 10 , a work hood  320  is connected around a circular opening  13   a  formed at a bottom wall portion  13  inside a chamber  12  by an annular rotation support  330 . The rotation support  330  includes a base portion  331 , a rotation portion  332 , a bearing portion  333 , a lip seal  334 , and a communication hole  335 . The configurations of the base portion  331 , the rotation portion  332 , the lip seal  334 , and the communication  335  are identical to those in the above third embodiment. 
     In  FIG. 10 , the base portion  331  is an L-shaped annular structure composed of a cylindrical portion  331   a  and an annular plate portion  331   b  projecting outward in the normal direction from one end of the cylindrical portion. The annular plate portion  331   b  is cylindrical on the inner periphery, and is airtightly fixed to a bottom wall portion  13  of the chamber  12  with bolts  336   a  over the whole periphery so as to overlap the inner periphery of a circular opening  13   a  of the chamber  12 . An inner peripheral portion of a cylindrical portion  331   a  forms an opening of the work hood  20  into which a worker inserts the upper body. 
     Meanwhile, the bearing portion  333  is fixed to the outer periphery of the cylindrical portion  331   a . In this fourth embodiment, a plurality of small ball bearings  333   a  constitutes the bearing portion  333 . These small ball bearings  333   a  are arranged annularly on the outer periphery of the cylindrical portion  331   a  of the base portion  331  and fixed at equal intervals with each shaft portion  333   c  toward the center of the ring. 
     In  FIG. 10 , the rotating portion  332  is an L-shaped annular structure composed of a cylindrical portion  332   a  and an annular plate portion  332   b  projecting upward in the cylindrical axis direction from an outer peripheral end of the cylindrical portion. The cylindrical portion  332   a  is disposed outside the cylindrical portion  331   a  of the base portion  331  so as to be coaxial therewith. An eaves portion  332   c  is formed on an upper portion of the inner periphery of the cylindrical portion  332   a  over the whole periphery. The eaves portion  332   c  is disposed so as to come into contact with an upper portion of an outer race  333   b  of a plurality of small bearings  333   a  fixed at equal intervals to the outer periphery of the cylindrical portion  331   a  of the base portion  331 . 
     In this fourth embodiment, since a plurality of small ball bearings  333   a  is used as the bearing portion  333 , a packing may be used in an annular gap  337  between the outer periphery of the cylindrical portion  331   a  of the base portion  331  and the eaves portion  332   c  of the upper portion of the inner periphery of the cylindrical portion  332   a  of the rotating portion  332 . 
     Meanwhile, the annular plate portion  332   b  is cylindrical on the outer periphery, and is airtightly fixed to an upper surface of the cylindrical portion  332   a  with a bolt  336   b  over the whole periphery so as to overlap the outer periphery of the cylindrical portion  332   a.  Also, two flat bands  323  are airtightly fixed to inner and outer surfaces of a base end portion  21   a  of a half suit  321  formed of a flexible material on an outer peripheral side surface of a circular plate portion  332   b.    
     Thus, in this fourth embodiment, the base portion  331  and the rotating portion  332  of the rotation support  330  come into contact with each other through the bearing portion  333  (a plurality of small ball bearings  333   a ). Accordingly, in the rotation support  330 , the rotating portion  332  fixing the half suit  321  can be rotatable at any angle including 360° opposite the base portion  331  fixed to the bottom wall portion  13  of the chamber  12 . 
     The communication hole  335  is connected to a decontamination gas supply unit, a compressed air supply unit, and a vacuum suction unit disposed in the external environment through a pipe. In this fourth embodiment, works in a sterile environment inside the chamber  12  and decontamination works are performed in the same manner as in the above first embodiment. Accordingly, the lip seal  334  complicated in structure and a small space  339  are decontaminated with high precision. 
     Fifth Embodiment 
     A fifth embodiment of the work hood according to the present invention will be described with reference to the drawings. In this fifth embodiment, the projecting position and functions of a sealing member (lip seal) are different from those in the above first embodiment.  FIG. 11  is a cross-sectional view (taken along the line C-C of  FIG. 2  at Part B in  FIG. 1 ) showing the configuration of a rotation support included in the work hood in the fifth embodiment. 
     In  FIG. 11 , a sealing member (lip seal)  434  is annularly projected on an upper surface  31   c  of an annular plate portion  431   b  in an annular gap  438  formed by a lower end surface  432   c  of a cylindrical portion  432   a  of a rotating portion  432  of a rotation support  430  and the upper surface  431   c  of an annular plate portion  31   b  of a base portion  431 . The lip seal  434  is formed of an elastic body such as synthetic rubber. The configurations of the base portion  431 , the rotation portion  432 , the bearing portion  433 , and the communication  435  are identical to those in the above first embodiment. 
     The lip seal according to this fifth embodiment, as described above, has different functions from the above first embodiment. In function, the lip seal  434  according to this fifth embodiment is configured to change the height of a projecting portion of the lip seal  434  projecting from the upper surface  31   c  of the annular plate portion  31   b . Thus, the lip seal  434  is slidably buried vertically from the annular plate portion  31   b,  and includes control mechanisms  434   a,    434   b,    434   c  for controlling the height of the projecting portion. 
     The control mechanisms include an air chamber  434   a  sealed at a base end portion (a portion buried inside the annular plate portion  31   b ) of the lip seal  434 . The air chamber  434   a  communicates into a pump  434   c  in the external environment through a pipe  434   b.  In cases where air is supplied to the air chamber  434   a  by operating the pump  434   c,  the air chamber  434   a  expands to push up the lip seal  434  from the upper surface  31   c  of the annular plate portion  31   b . Meanwhile, in cases where the air is discharged from the air chamber  434   a  by shifting and operating the pump  434   c,  the air chamber  434   a  shrinks to push down the lip seal  434  from the upper surface  31   c  of the annular plate portion  31   b.    
     Accordingly, the height of the projecting portion of the lip seal  434  can be adjusted depending on each work in a sterile environment inside the chamber  12  or each decontamination work. Specifically, the distance between a projecting tip portion of the lip seal  434  and a wall surface in opposition thereto (the lower end surface  432   c  of the cylindrical portion  432   a  of the rotating portion  432 ) can be controlled, or the projecting tip portion and the wall surface can come into contact with each other. 
     For example, in cases where a work is performed in a sterile environment inside the chamber  12 , the sterile state can readily be maintained and the work hood can readily be rotated by preparing a slight gap between the projecting tip portion of the lip seal  434  and the wall surface or allowing the same to slightly come into contact with each other. Meanwhile, in cases where a decontamination gas is supplied or aerated in a decontamination work, a gap is prepared between the projecting tip portion of the lip seal  434  and the wall surface to allow a decontamination gas or clean air for aeration to pass readily, resulting in ensured decontamination effects at the sealing portion. 
     In this fifth embodiment, the projecting position of the lip seal  434  is on the upper surface  31   c  of the annular plate portion  31   b  of the base portion  431 , but it is not restricted thereto, and it may project into the lower end surface  432   c  of the cylindrical portion  432   a  of the rotating portion  432  as in the above first embodiment. In this fifth embodiment, the lip seal  434  is moved up and down by operating the control mechanisms  434   a,    434   b,    434   c,  but it is not restricted thereto, and an expansion packing may be used as a sealing member by air pressure and the air pressure in the expansion packing may be adjusted to control the distance between the expansion packing and a wall surface in opposition thereto. 
     Sixth Embodiment 
     A sixth embodiment of the work hood according to the present invention will be described with reference to the drawings. In this sixth embodiment, in a decontamination work inside a chamber  12 , a drive unit for automatically rotating a half suit is provided. The configurations of the portions other than the drive unit are the same as those in the above first embodiment.  FIG. 12  is a schematic cross-sectional view showing a rotation support of the work hood including the drive unit in the sixth embodiment viewed from the front. 
     In  FIG. 12 , a drive unit  50  comes into contact with an inner peripheral portion of a rotation support  30  provided in a circular opening  13   a  formed at a bottom wall portion  13  inside the chamber  12  to be fixed. The drive unit  50  includes a stationary disk portion  51 , a rotary disk portion  52 , a support shaft portion  53 , a drive motor  54 , and a compressed air supply unit  55 . 
     The stationary disk portion  51  includes a disk  51   a  having a diameter engageable into an annular inner peripheral surface of a base portion  31  of the rotation support  30  and an annular expansion packing  51   b  around the outer peripheral surface thereof. In  FIG. 12 , the expansion packing  51   b  expands to come into contact with the annular inner peripheral surface of the base portion  31  to be airtightly fixed. The rotary disk portion  52  includes a disk  52   a  having a diameter engageable into an annular inner peripheral surface of a rotating portion  32  of the rotation support  30  and an annular expansion packing  52   b  around the outer peripheral surface thereof. In  FIG. 12 , the expansion packing  52   b  expands to come into contact with the annular inner peripheral surface of the rotating portion  32  to be airtightly fixed. 
     The support shaft portion  53  is composed of double pipes  53   a,    53   b,  passing through the axis of center with the stationary disk portion  51  and the rotary disk portion  52  to allow an outer pipe  53   a  and an inner pipe  53   b  to support the stationary disk portion  51  and the rotary disk portion  52 , respectively. The inner pipe  53   b  is operated with the drive motor  54  disposed on a lower surface of the stationary disk portion  51  to rotate the rotary disk portion  52  opposite the stationary disk portion  51 . In addition, the compressed air supply unit  55  supplies compressed air to the inside of the half suit  21  fixed at the rotary disk portion  52  through a supply pipe  55   a  passing through the inside of the support shaft portion  53  in the external environment to expand the half suit  21 . 
     Thus, in this sixth embodiment, the drive unit  50  is fixed to the inner periphery of the rotation support  30 . Accordingly, the half suit  21  fixed at the rotating portion  32  of the rotation  30  can be rotated opposite the base portion  31  fixed at the bottom wall portion  13  of the chamber  12  by driving the drive motor  54  in an expansion state. 
     The communication hole  35  is connected to a decontamination gas supply unit, a compressed air supply unit, and a vacuum suction unit disposed in the external environment through a pipe. In this sixth embodiment, a decontamination work inside the chamber is performed in the same manner as in the above first embodiment. Accordingly, a lip seal  34  complicated in structure and a small space  39  are decontaminated with higher precision. 
     Therefore, each of the above embodiments can provide a work hood that allows for free rotation in a work box to provide a wide work area and easy decontamination of a sealing portion at the boundary between the work hood and the work box. 
     REFERENCE SIGNS LIST 
       10  . . . Isolator device,  11  . . . Leg portion,  12  . . . Work box (Chamber),  13  . . . Bottom wall portion,  13   a  . . . Opening,  20 ,  120 ,  220 ,  320 ,  420  . . . Work hood,  21 ,  121 ,  221 ,  321 ,  421  . . . Half suit,  22 ,  122 ,  422  . . . O-ring,  223 ,  323  . . . Flat band,  30 ,  130 ,  230 ,  330 ,  430  . . . Rotation support,  31 ,  131 ,  231 ,  331 ,  431  . . . Base portion,  31   a,    131   a,    231   a,    331   a ,  431   a  . . . Cylindrical portion,  31   b,    131   b,    231   b,    331   b ,  431   b  . . . Annular plate portion,  32 ,  132 ,  232 ,  332 ,  432  . . . Rotating portion,  32   a,    132   a,    232   a,    332   a ,  432   a  . . . Cylindrical portion,  32   b,    132   b,    232   b,    332   b ,  432   b  . . . Annular plate portion,  33 ,  133 ,  233 ,  333 ,  433  . . . Bearing portion,  333   a  . . . Small bearing,  33   a,    133   a ,  233   a,    433   a  . . . Inner race,  33   b,    133   b,    233   b,    333   b ,  433   b  . . . Outer race,  333   c  . . . Shaft portion,  34 ,  134 ,  234 ,  334 ,  434  . . . sealing member (lip seal),  434   a  . . . Air chamber,  434   b  . . . Pipe,  434   c  . . . Pump,  35 ,  135 ,  235 ,  335 ,  435  . . . Communication hole,  36 ,  136 ,  236 ,  336 ,  436  . . . Bolt,  37 ,  38 ,  137 ,  138 ,  237 ,  238 ,  337 ,  338 ,  437 ,  438  . . . Gap,  39 ,  139 ,  239 ,  339 ,  439  . . . Small space,  41  . . . Decontamination gas supply unit,  42  . . . Depressurizing suction device,  43  . . . Pipe,  44  . . . Three-way valve,  45  . . . HEPA filter,  46  . . . Catalytic device,  50  . . . Drive unit,  51  . . . Stationary disk portion,  52  . . . Rotary disk portion,  51   a,    52   a  . . . Disk,  51   b ,  52   b  . . . Expansion packing,  53  . . . Support shaft portion,  53   a  . . . Outer pipe,  53   b  . . . Inner pipe,  54  . . . Drive motor,  55  . . . Compressed air supply unit,  55   a  . . . Supply pipe.