Patent Publication Number: US-11027233-B2

Title: Absorption rotor, rotor element, method of manufacturing absorption rotor, and method of manufacturing rotor element

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is entering into national phase of PCT Application No. PCT/JP2016/073989, filed on Aug. 17, 2016, the entire contents of which are hereby incorporated by reference into this application. 
     TECHNICAL FIELD 
     The present invention relates to an absorption rotor arranged in a flow passage of a gas containing a substance to be absorbed, the absorption rotor that absorbs the substance to be absorbed when the gas passes through, a rotor element, a method of manufacturing an absorption rotor, and a method of manufacturing a rotor element. 
     BACKGROUND ART 
     There is a need for detoxifying a gas containing a VOC (volatile organic compound) which is discharged from various plants such as a printing plant, a painting plant, and a semiconductor plant to discharge to the atmosphere. As a technology to treat such a gas containing a VOC, for example, there is a known system using an absorption rotor described in Patent Literature 1 below. 
     The absorption rotor described in Patent Literature 1 includes a honeycomb body (absorption member) placed between a boss positioned in a center portion and spokes extending from the boss to an outer circumferential ring, the honeycomb body that absorbs a VOC. In the above system, after the VOC is absorbed by letting the gas pass through while the absorption rotor is rotated about the rotation axis, the heated air is blown to a portion onto which the VOC is absorbed, so that the VOC is detached. 
     CITATION LIST 
     Patent Literature 
     PATENT LITERATURE 1: JP 2004-113844 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the above conventional technology, the spoke and the honeycomb body are adhered to each other via a caulking material. However, since the gas passing through the absorption rotor at the time of absorbing and detaching the VOC has a high temperature, there is a fear that adhesion between the spoke and the honeycomb body is removed upon continuous usage. When the adhesion between the spoke and the honeycomb body is removed, the honeycomb body could be dropped off when the absorption rotor is rotated. 
     Therefore, in order to prevent the honeycomb body from dropping off, it is thought that an edge portion of an end surface (surface through which the gas passes) of the honeycomb body and the spoke are fixed by a metal fitting or the like. However, the end surface of the honeycomb body is a flow passage of the gas. Thus, the honeycomb body may be buckled by the metal fitting due to an influence of wind pressure, so that the honeycomb body may be damaged. 
     In such a way, a problem to tackle is to prevent the honeycomb body from dropping off the absorption rotor without damaging the honeycomb body (absorption member). 
     The present invention is achieved to address the above problem, and an object thereof is to provide an absorption rotor capable of preventing an absorption member from dropping off while reducing damage to the absorption member, a rotor element, a method of manufacturing an absorption rotor, and a method of manufacturing a rotor element. 
     Solution to Problem 
     The above problem is solved by an absorption rotor according to the present invention, the absorption rotor being provided in a flow passage of a gas containing a substance to be absorbed, the absorption rotor through which the gas passes while the absorption rotor is rotated about the rotation axis, the absorption rotor including plural plate members extending in a radial manner from the circumference of the rotation axis, a tubular outer edge member coupling end portions of the plural plate members, an absorption member accommodated in a space which is surrounded by the plural plate members and the outer edge member, the absorption member that absorbs the substance to be absorbed when the gas passes through, and a drop-off prevention member respectively fixed to the plate member and the absorption member, the drop-off prevention member that prevents the absorption member from dropping off the plate member, wherein the drop-off prevention member is arranged between the absorption member and the plate member, and between a surface from which the gas flows into the absorption member and a surface from which the gas flows out of the absorption member. 
     With the above absorption rotor, by providing the drop-off prevention member fixed both to the absorption member and the plate member, the absorption member can be prevented from dropping off the plate member. 
     With the above absorption rotor, the drop-off prevention member is not attached to the surfaces through which the gas passes in the absorption member. Thus, the absorption member is not buckled by the drop-off prevention member due to wind pressure. 
     That is, with the above absorption rotor, the absorption member can be prevented from dropping off while reducing damage to the absorption member. 
     With the above absorption rotor, the drop-off prevention member is provided at a position not exposed to the exterior. Thus, a design property of the absorption rotor becomes favorable. 
     In the above absorption rotor, the drop-off prevention member may have an embedded portion embedded in the absorption member, and an exposed portion exposed from the absorption member, and the embedded portion may be fixed to the absorption member, and the exposed portion may be fixed to the plate member. 
     By doing so, by embedding and attaching part of the drop-off prevention member into the absorption member, attachment of the drop-off prevention member to the absorption member can be strengthened. 
     In the above absorption rotor, the plate member and the drop-off prevention member may be respectively made of metal, and an outer end portion of the exposed portion on the side close to the outer edge member and the end portion of the plate member may be welded to each other. 
     By doing so, the number of welding points for fixing the drop-off prevention member to the plate member can be reduced. Thereby, a burden of a welding task can be reduced. 
     In the above absorption rotor, a hole from which the outer end portion of the drop-off prevention member and the end portion of the plate member are exposed may be formed in the outer edge member. 
     By doing so, the drop-off prevention member and the plate member can be welded from the outside of the outer edge member. Thereby, a working property in assembling of the absorption rotor can be improved. 
     From the hole formed in the outer edge member, a joining state between the drop-off prevention member and the plate member can be confirmed. 
     In the above absorption rotor, the exposed portion may be a flat plate extending from the vicinity of the center portion toward the outer edge member, and the embedded portion may have plural extending portions extending substantially perpendicularly from the exposed portion toward the absorption member. 
     By doing so, the drop-off prevention member can be strongly fixed to the absorption member. 
     In the above absorption rotor, the plate member may have a holding portion that holds an inner end portion of the exposed portion on the side close to the center portion. 
     By doing so, position displacement of the drop-off prevention member can be prevented. Thereby, the drop-off prevention member is not easily dropped off. 
     In the above absorption rotor, the holding portion may be formed by two metal blocks provided on a surface of the plate member facing the absorption member, the metal blocks that nip the inner end portion of the exposed portion. 
     By doing so, the holding portion can function as a guide at the time of attaching the absorption member to which the drop-off prevention member is attached to the plate member. Thereby, with the above absorption rotor, the absorption member can be attached to the spoke at the right position. 
     The above absorption rotor may include reinforcement members attached to the absorption member at positions across the drop-off prevention member with respect to the flow passage of the gas, the reinforcement members that reinforce fixing of the drop-off prevention member. 
     By doing so, the position displacement of the drop-off prevention member can be prevented. 
     The above problem is solved by a rotor element according to the present invention, the rotor element being provided in an absorption rotor which is provided in a flow passage of a gas containing a substance to be absorbed, the absorption rotor through which the gas passes while the absorption rotor is rotated about the rotation axis, the rotor element including an absorption member accommodated in a space which is surrounded by plural plate members extending in a radial manner from the circumference of the rotation axis and a tubular outer edge member coupling end portions of the plural plate members, the absorption member that absorbs the substance to be absorbed when the gas passes through, and a drop-off prevention member respectively fixed to the plate member and the absorption member, the drop-off prevention member that prevents the absorption member from dropping off the plate member, wherein the drop-off prevention member is arranged between the absorption member and the plate member, and between a surface from which the gas flows into the absorption member and a surface from which the gas flows out of the absorption member. 
     A method of manufacturing an absorption rotor according to the present invention is a method of manufacturing an absorption rotor including plural plate members extending in a radial manner from the circumference of the rotation axis, a tubular outer edge member coupling end portions of the plural plate members, an absorption member accommodated in a space which is surrounded by the plural plate members and the outer edge member, the absorption member that absorbs a substance to be absorbed when a gas containing the substance to be absorbed passes through, and a drop-off prevention member respectively fixed to the plate member and the absorption member, the drop-off prevention member that prevents the absorption member from dropping off the plate member, the method including the step of arranging the drop-off prevention member between the absorption member and the plate member, and between a surface from which the gas flows into the absorption member and a surface from which the gas flows out of the absorption member. 
     A method of manufacturing a rotor element according to the present invention is a method of manufacturing a rotor element including an absorption member accommodated in a space which is surrounded by plural plate members extending in a radial manner from the circumference of the rotation axis and a tubular outer edge member coupling end portions of the plural plate members, the absorption member that absorbs a substance to be absorbed when a gas containing the substance to be absorbed passes through, and a drop-off prevention member respectively fixed to the plate member and the absorption member, the drop-off prevention member that prevents the absorption member from dropping off the plate member, the method including the step of arranging the drop-off prevention member between the absorption member and the plate member, and between a surface from which the gas flows into the absorption member and a surface from which the gas flows out of the absorption member. 
     Advantageous Effects of Invention 
     According to the present invention, the absorption member can be prevented from dropping off while reducing damage to the absorption member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an absorption rotor according to the present embodiment. 
         FIG. 2  is an exploded perspective view of a partial configuration of the absorption rotor. 
         FIG. 3  is an exploded perspective view of a rotor element. 
         FIG. 4  is a view for illustrating attachment of the rotor element to a spoke. 
         FIG. 5  is a view showing a state where the rotor element is attached to the spoke. 
         FIG. 6  is a sectional view taken along the line VI-VI of  FIG. 5 . 
         FIG. 7  is an enlarged view of the vicinity of a hole formed in a rim. 
         FIG. 8  is a view for illustrating another example of the attachment of the rotor element to the spoke. 
         FIG. 9  is a sectional view taken along the line IX-IX of  FIG. 8  in a state where the rotor element is attached to the spoke. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an absorption rotor  1  according to an embodiment of the present invention (hereinafter, referred to as the present embodiment) will be described with reference to  FIGS. 1 to 9 . The embodiment to be described below does not limit the present invention but only serves one example for facilitating understanding of the present invention. That is, the shape, size, arrangement, and the like of members to be described below can be modified or improved without departing from the gist of the present invention, and the present invention includes equivalents thereof as a matter of course. 
     Firstly, outlines of  FIGS. 1 to 7  will be described.  FIG. 1  is a perspective view of the absorption rotor  1  according to the present embodiment.  FIG. 2  is an exploded perspective view of a partial configuration of the absorption rotor  1 .  FIG. 3  is an exploded perspective view of a rotor element  10 .  FIG. 4  is a view for illustrating attachment of the rotor element  10  to a spoke  3 .  FIG. 5  is a view showing a state where the rotor element  10  is attached to the spoke  3 .  FIG. 6  is a sectional view taken along the line VI-VI of  FIG. 5 .  FIG. 7  is an enlarged view of the vicinity of a hole  6  formed in a rim  4 . 
     The absorption rotor  1  according to the present embodiment is a device provided in a flow passage of a gas containing a VOC which serves as a substance to be absorbed, for example, the device that absorbs the VOC when the gas passes through the interior of the absorption rotor  1 . 
     That is, as shown in  FIG. 1 , an input gas Ga containing a substance P to be absorbed flows into an inflow surface Fa of the absorption rotor  1 . At the time of passing through the absorption rotor  1 , the substance P to be absorbed is absorbed. In such a way, an output gas Gb from which the substance P to be absorbed is removed is discharged from an outflow surface Fb. Hereinafter, a configuration of the absorption rotor  1  will be described. 
     As shown in  FIG. 1 , the absorption rotor  1  has a hub  2  provided in a center portion, the spokes  3  extending in a radial manner from the hub  2 , and the tubular rim  4  coupling end portions of the spokes  3  as frame members. 
     As shown in  FIGS. 1 and 2 , an axial hole  2 A is formed in a center portion of the hub  2 , and an axial member  5  is inserted into the axial hole  2 A. In such a way, the absorption rotor  1  can be rotated with the axial member  5  as the rotation axis, and the gas passes through while the absorption rotor is rotated about the axial member  5 . 
       FIG. 2  shows a state where the rotor element  10  and the axial member  5  are detached from the frame members of the absorption rotor  1 . 
     As shown in  FIGS. 1 and 2 , in each of spaces surrounded by the spokes  3  and the rim  4  (eight spaces in the present embodiment), the rotor element  10  having a substantially fan-shaped end surface is respectively accommodated. 
     As shown in  FIGS. 2 and 3 , the rotor element  10  includes an absorption member  11  that absorbs the substance P to be absorbed, a drop-off prevention member  12 , and reinforcement members  13 . The drop-off prevention member  12  and the reinforcement members  13  are provided on a side surface  11 C (surface facing the spoke  3 ) of the absorption member  11 . 
     The absorption member  11  is an absorption element of a honeycomb structure, in which the flow passage of the gas is formed in the direction along the axial member  5 . In the absorption member  11 , an absorbent such as activated carbon and hydrophobic zeolite is supported by a honeycomb structure body formed by corrugating an inorganic fabric paper, for example. 
     As shown in  FIG. 3 , a substantially fan-shaped end surface  11 A and an end surface  11 B of a back surface thereof in the absorption member  11  serve as surfaces through which the gas passes. 
     As shown in  FIG. 3 , the drop-off prevention member  12  is a metal member (such as a steel plate) having a substantially U-shaped section and extending substantially from an inner end portion  11 E to an outer end portion  11 F. 
     Specifically, as shown in  FIGS. 3 and 6 , the drop-off prevention member  12  includes a flat plate-shaped exposed portion  12 A placed along the side surface  11 C of the absorption member  11 , and embedded portions  12 B extending from the exposed portion  12 A to the side of the absorption member  11 . 
     The drop-off prevention member  12  is attached to the absorption member  11  as follows, for example. That is, in a state where a caulking material  14 A is applied to a surface of the drop-off prevention member  12  on the side facing the absorption member  11 , the embedded portions  12 B are inserted into slits  11 D formed on the side surface  11 C of the absorption member  11 . 
     The slits  11 D are formed in a substantially center part of the side surface  11 C (specifically, in a substantially center portion in the thickness direction which is orthogonal to the radial direction and the circumferential direction of the substantially fan-shaped absorption member  11  shown in  FIG. 3 ). Thereby, the drop-off prevention member  12  is attached to the substantially center part of the side surface  11 C. 
     An outer end portion  12 D of the drop-off prevention member  12  is attached at the substantially same position as the outer end portion  11 F of the absorption member  11 . 
     As shown in  FIG. 3 , the reinforcement member  13  is a metal member having an L-shaped section. Specifically, as shown in  FIGS. 3 and 6 , the reinforcement member  13  has a flat plate-shaped exposed portion  13 A placed along the side surface  11 C of the absorption member  11 , and an embedded portion  13 B extending from the exposed portion  13 A to the side of the absorption member  11 . 
     The reinforcement member  13  is attached to the absorption member  11  as follows, for example. That is, in a state where an adhesion layer made of the caulking material  14 A such as silicon is formed on a surface of the reinforcement member  13  on the side facing the absorption member  11 , the embedded portion  13 B is inserted at a position adjacent to the embedded portion  12 B. The insertion position of the embedded portion  13 B may be the slit  11 D, for example, or may be a slit separately formed at a position adjacent to the slit  11 D. 
     The reinforcement members  13  are attached on both the sides of the drop-off prevention member  12 . By attaching the reinforcement members  13  on both the sides of the drop-off prevention member  12  in such a way, position displacement or warp of the drop-off prevention member  12  is suppressed. 
     A side surface on the opposite side of the side surface  11 C shown in  FIG. 3  has the same configuration. 
     Next, the attachment of the rotor element  10  to the spoke  3  will be described with reference to  FIGS. 4 to 6 . 
       FIG. 4  extracts and shows part of the spoke  3 . As shown in  FIG. 4 , holding portions  7  are formed in a part coupled to the hub  2  on an attachment surface  3 A of the spoke  3  to which the rotor element  10  is attached. 
     The holding portions  7  are formed by plural nipping bodies that nip an inner end portion  12 C, and the above nipping bodies are, for example, blocks made of metal (such as steel plates). In the present embodiment, two nipping bodies are attached to the attachment surface  3 A of the spoke  3 . The two nipping bodies are separated from each other so that the drop-off prevention member  12  can be inserted between both the nipping bodies. The holding portions  7  may be attached to the attachment surface  3 A of the spoke  3  by, for example, welding. The above method of welding is not particularly limited but, for example, arc welding, laser welding, and the like can be used. 
     The step of attaching the rotor element  10  between the two spokes  3  extending from the hub  2  is as follows, for example. That is, in a state where an adhesion layer made of a caulking material  14 B such as silicon is formed on the attachment surface  3 A, the rotor element  10  is attached between the two spokes  3  extending from the hub  2 . The rotor element  10  is pushed into the spoke  3  in such a manner that the inner end portion  12 C of the drop-off prevention member  12  is nipped between the two holding portions  7 . 
     By attaching the rotor element  10  between the spokes  3 , the absorption rotor  1  is manufactured. 
     By the above step, the rotor element  10  in which the drop-off prevention member  12  is arranged between the absorption member  11  and the spoke  3 , and between the end surface  11 A from which the gas flows into the absorption member  11  and the end surface  11 B from which the gas flows out of the absorption member, and the absorption rotor  1  including such a rotor element  10  can be manufactured. 
       FIG. 5  shows a state where the rotor element  10  is attached to the spoke  3 . The side surface  11 C of the rotor element  10  and the attachment surface  3 A are adhered to each other via the caulking material  14 B. Thereby, in a state where a gap between the rotor element  10  and the spoke  3  is charged with the caulking material  14 B, the rotor element  10  is fixed to the spoke  3 . 
     In such a way, the gap between the rotor element  10  and the spoke  3  is filled with the caulking material  14 B. Thus, the gas flowing into the absorption rotor  1  can be secured to pass through the absorption member  11 . 
     In a state where the inner end portion  12 C of the drop-off prevention member  12  provided in the rotor element  10  is nipped by the two holding portions  7  provided in the spoke  3 , the outer end portion  12 D of the drop-off prevention member  12  is welded to the spoke  3 . 
     Thereby, both ends of the drop-off prevention member  12  are fixed to the spoke  3 . As a result, the attachment between the rotor element  10  and the spoke  3  can be more strengthened, so that the rotor element  10  is prevented from dropping off the spoke  3 . 
     As shown in  FIGS. 1 and 7 , in the rim  4 , the hole  6  may be formed at a position where the spoke  3  and the outer end portion  12 D of the drop-off prevention member  12  are abutted with each other. The spoke  3  and the outer end portion  12 D exposed from the hole  6  may be welded from the exterior of the rim  4 . 
     A welded portion  15  shown in  FIG. 7  shows a welding mark of the outer end portion  12 D of the drop-off prevention member  12  and the spoke  3 . The above method of welding is not particularly limited but, for example, arc welding, laser welding, and the like can be used. 
     Another example of the attachment of the rotor element  10  to the spoke  3  will be described with reference to  FIGS. 8 and 9 . 
       FIG. 8  is a view for illustrating another example of the attachment of the rotor element to the spoke.  FIG. 9  is a sectional view taken along the line IX-IX of  FIG. 8  in a state where the rotor element is attached to the spoke. 
     In the example to be described below, the drop-off prevention member  12  is attached to the spoke  3  in advance, and then the absorption member  11  is attached to the spoke  3  to which the drop-off prevention member  12  is attached. 
     As shown in  FIG. 8 , a through hole  21  is formed in a rear end of the spoke  3  which is a part facing the drop-off prevention member  12 . A through hole is also formed in a part of the drop-off prevention member  12  facing the through hole  21 . 
     As shown in  FIG. 9 , two drop-off prevention members  12  are arranged to face each other across the spoke  3 . The inner end portion  12 C of the drop-off prevention member  12  is nipped by the holding portions  7 . 
     For the drop-off prevention members  12  arranged to face each other across the spoke  3 , in a state where a bolt  22  is inserted into the through hole  21  via a washer  24 , an end portion of the bolt  22  is fastened by a nut  23 . Thereby, the drop-off prevention members  12  are fixed to the spoke  3 . 
     Next, the adhesion layer made of the caulking material such as silicon is formed on the attachment surface  3 A of the spoke  3  to which the drop-off prevention member  12  is attached. The absorption member  11  to which the reinforcement members  13  are attached is pushed in to the spoke  3  to which the drop-off prevention member  12  is attached, so that the embedded portions  12 B of the drop-off prevention member  12  are inserted into the slits  11 D of the absorption member  11 . In such a way, the rotor element  10  can be attached to the spoke  3 . 
     By attaching the rotor element  10  between the spokes  3 , the absorption rotor  1  is manufactured. 
     By the above step, the rotor element  10  in which the drop-off prevention member  12  is arranged between the absorption member  11  and the spoke  3 , and between the end surface  11 A from which the gas flows into the absorption member  11  and the end surface  11 B from which the gas flows out of the absorption member, and the absorption rotor  1  including such a rotor element  10  are manufactured. 
     With the absorption rotor  1  according to the present embodiment described above, by providing the drop-off prevention member  12  fixed both to the absorption member  11  and the spoke  3 , the absorption member  11  can be prevented from dropping off the spoke  3 . 
     With the absorption rotor  1 , the drop-off prevention member  12  is not attached to the end surface  11 A and the end surface  11 B through which the gas passes in the absorption member  11 . Thus, the absorption member  11  is not buckled by the drop-off prevention member  12  due to wind pressure of the gas. 
     That is, with the absorption rotor  1 , the absorption member  11  can be prevented from dropping off while reducing damage to the absorption member  11 . 
     With the absorption rotor  1 , the drop-off prevention member  12  is provided at a position not exposed to the exterior. Thus, a design property of the absorption rotor becomes favorable. 
     With the absorption rotor  1 , by embedding and attaching part of the drop-off prevention member  12  into the absorption member  11 , attachment of the drop-off prevention member  12  to the absorption member  11  can be strengthened. 
     With the absorption rotor  1 , welding points for fixing the drop-off prevention member  12  to the spoke  3  may be only the outer end portion  12 D of the drop-off prevention member  12 . Thus, the number of the welding points can be reduced. Thereby, a burden of a welding task at the time of attaching the drop-off prevention member  12  to the spoke  3  can be reduced. 
     With the absorption rotor  1 , the hole  6  from which the outer end portion  12 D of the drop-off prevention member  12  and the end portion of the spoke  3  are exposed is formed in the rim  4 . Thus, the drop-off prevention member  12  and the spoke  3  can be welded from the outside of the rim  4 . Thereby, a working property in assembling of the absorption rotor is improved. 
     From the hole  6  formed in the rim  4 , a joining state between the drop-off prevention member  12  and the spoke  3  can be confirmed. 
     With the absorption rotor  1 , the drop-off prevention member  12  is formed by a metal member having a substantially U-shaped section, and both the end portions are embedded in the absorption member  11 . Thus, the drop-off prevention member  12  can be strongly fixed to the absorption member  11 . 
     With the absorption rotor  1 , the spoke  3  includes the holding portions  7  that hold the inner end portion  12 C of the drop-off prevention member  12  (exposed portion  12 A) on the side close to the hub  2 . Thus, the position displacement of the drop-off prevention member  12  can be prevented. Thereby, the drop-off prevention member  12  is not easily dropped off the spoke  3 . 
     The holding portions  7  function as a guide at the time of attaching the rotor element  10  to the spoke  3 . Thus, the rotor element  10  is easily attached to the spoke  3  at the right position. 
     The absorption rotor  1  includes the reinforcement members  13  attached to the absorption member  11  at positions across the drop-off prevention member  12  with respect to the flow passage of the gas. Thus, the position displacement of the drop-off prevention member  12  can be prevented. 
     With the absorption rotor  1 , for the rotor element  10  and the spoke  3 , two types of joining including the joining using the caulking material and the joining by welding are used. Thus, redundancy of the joining between the rotor element  10  and the spoke  3  can be enhanced. Thereby, the rotor element  10  is not easily dropped off the spoke  3 . 
     The present invention is not limited to the above embodiment. For example, in the above embodiment, the example in which the absorption rotor  1  is applied to a VOC treatment device is described. However, the absorption rotor  1  may be applied to a dehumidifying device, a deodorizing device, and the like. 
     In the above embodiment, the outer end portion  12 D of the drop-off prevention member  12  and the spoke  3  are joined to each other by welding. However, the outer end portion and the spoke may be joined mechanically by using bolts, nuts, and the like. 
     In the above embodiment, the example in which the two reinforcement members  13  are provided for the drop-off prevention member  12  is described. However, the number of the reinforcement members  13  may be one, three, or more. 
     Arrangement of the reinforcement members  13  is also not limited to the one shown in  FIG. 3  and the like. For example, regarding the rotor element  10  shown in  FIG. 3 , right and left positions of the reinforcement members  13  arranged on the upper and lower sides of the drop-off prevention member  12  may be displaced from each other. 
     In the above embodiment, the drop-off prevention member  12  has the exposed portion  12 A and the embedded portions  12 B. However, the drop-off prevention member  12  may be formed only by an embedded portion  12 B. In this case, one end portion of the embedded portion  12 B can be fixed to the spoke  3  and the other end portion can be embedded in the absorption member  11 . 
     In the above embodiment, the two (two streaks of) embedded portions  12 B of the drop-off prevention member  12  are provided. However, one, three, or more (streaks of) embedded portions  12 B may be provided. 
     In the above embodiment, the holding portions  7  are formed by the two nipping bodies. However, the holding portions may be formed by three or more nipping bodies. 
     In the above embodiment, as one example of the attachment of the rotor element  10  to the spoke  3 , the drop-off prevention member  12  is attached to the spoke  3  in advance as in  FIGS. 8 and 9 , and then the absorption member  11  (rotor element  10 ) is attached to the drop-off prevention member  12 . However, the present invention is not limited to this. For example, the drop-off prevention member  12  may be attached to the absorption member  11  in advance, and then the drop-off prevention member  12  may be attached to the spoke  3 . In this case, at the time of attaching one drop-off prevention member  12  to the spoke  3 , firstly, part of a portion of the absorption member  11 , the portion to which the drop-off prevention member  12  is attached is cut out, and a space for installing any one of a head portion of a bolt and a nut to be screwed onto the leading end side of a threaded portion of the bolt is provided in the absorption member  11 . Then, the head portion of the bolt or the nut is arranged in the space, and the drop-off prevention member  12  and the spoke  3  are fixed by the bolt and the nut. 
     REFERENCE SIGNS LIST 
     
         
           1 : Absorption rotor 
           2 : Hub (center portion) 
           2 A: Axial hole 
           3 : Spoke (plate member) 
           3 A: Attachment surface 
           4 : Rim (outer edge member) 
           5 : Axial member (rotation axis) 
           6 : Hole 
           7 : Holding portion (nipping body) 
           10 : Rotor element 
           11 : Absorption member 
           11 A: End surface 
           11 B: End surface 
           11 C: Side surface 
           11 D: Slit 
           11 E: Inner end portion 
           11 F: Outer end portion 
           12 : Drop-off prevention member 
           12 A: Exposed portion 
           12 B: Embedded portion 
           12 C: Inner end portion 
           12 D: Outer end portion 
           13 : Reinforcement member 
           13 A: Exposed portion 
           13 B: Embedded portion 
           14 A: Caulking material 
           14 B: Caulking material 
           15 : Welded portion 
           20 : Vicinity of hole 
           21 : Through hole 
           22 : Bolt 
           23 : Nut 
           24 : Washer 
         Fa: Inflow surface 
         Fb: Outflow surface 
         Ga: Input gas 
         Gb: Output gas 
         P: Substance to be absorbed