Patent Publication Number: US-2022235813-A1

Title: Washer and fastening structure

Description:
TECHNICAL FIELD 
     The present invention relates to a washer and a fastening structure. 
     BACKGROUND ART 
     Conventionally, a seal washer has been known that, when two fixing members are fixed by bolts, secures a sealing property between the fixing member and the bolt. There is a seal washer that has, for example, a washer body formed of a metal in a ring shape, and a seal portion formed of an elastic material on the surface of the washer body. The seal washer seals the space between the head of the bolt or the washer that is in contact with the head of the bolt and the fixing member with a seal portion. 
     However, for example, when a plurality of members having an insulating film are fastened and fixed, it may be difficult to conduct the plurality of members to the same potential while securing the sealing property. 
     PRIOR ART DOCUMENTS 
     Patent Document 
     [Patent Document 1] 
     Japanese Unexamined Patent Application, First Publication No. 2013-2621 
     SUMMARY OF INVENTION 
     Problems to be Solved by the Invention 
     The problem to be solved by the present invention is to provide a washer and a fastening structure that can fix a plurality of fixing members in a conductive state while securing sealing properties. 
     Means for Solving the Problems 
     The washer of the embodiment includes a conductive main body, a first seal portion, and a second seal portion. The main body has an annular plate-shaped body and a protruding portion. The protruding portion protrudes in the thickness direction from the outer peripheral portion of the plate-shaped body. The first seal portion covers the inner peripheral surface at the inner peripheral portion and both surfaces in the thickness direction of the plate-shaped body. The second seal portion covers at least the distal end portion of the protruding portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a fastening structure according to an embodiment. 
         FIG. 2  is an exploded perspective view of the fastening structure according to the embodiment. 
         FIG. 3  is a sectional view showing before and after fastening of fastening structure of the embodiment 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a washer and a fastening structure of the embodiment will be described with reference to the drawings. 
       FIG. 1  is a perspective view of a fastening structure  10  according to the embodiment.  FIG. 2  is an exploded perspective view of the fastening structure  10  according to the embodiment.  FIG. 3  is a sectional view showing before and after fastening of fastening structure  10  of the embodiment. 
     Hereinafter, the X-axis, Y-axis, and Z-axis directions orthogonal to each other in the three-dimensional space are directions parallel to the respective axes. For example, the left-right direction of the fastening structure  10  is parallel to the X-axis direction. The front-back direction of the fastening structure  10  is parallel to the Y-axis direction. The axial direction of the fastening structure  10  is parallel to the Z-axis direction. 
     The fastening structure  10  according to the embodiment is provided, for example, on the housing of various panels provided in electrical equipment or the like. The panels are a power distribution panel, a power distribution panel, a control panel, and the like that constitute a power conversion device, a power supply device, a motor drive device, and the like. The housing houses various electric devices inside. Various electric devices include a transformer, a switch, a circuit breaker, a measuring device, a control device, and the like. 
     As shown in  FIGS. 1, 2, and 3 , the fastening structure  10  according to the embodiment includes a screw  11 , a first washer (an example of a washer in claim  1 )  12 , and a second washer (an example of an annular member in the claims)  13  to be used by being superimposed on the first washer  12 . The fastening structure  10  fixes, for example, a first fixing member  21  and a second fixing member  22  that are stacked and arranged in the thickness direction. The thickness direction of the first fixing member  21  and the second fixing member  22  is parallel to the axial direction. 
     The first fixing member  21  and the second fixing member  22  include conductive main bodies  21   a ,  22   a  and electrically insulating coatings (coating layers)  21   b ,  22   b . Each coating  21   b ,  22   b  covers the surface of each main body  21   a ,  22   a . The first fixing member  21  and the second fixing member  22  are electrically insulated by being in contact with each other via the coatings  21   b  and  22   b  in a state where the fastening structure  10  is in a non-fastened state. 
     The screw  11  is formed of a conductive material. The screw  11  has a head  31  and a shaft  32  protruding from the head  31 . 
     The head  31  includes a flange portion  31   a  provided at an end on the side of the shaft portion  32  in the axial direction. The outer shape of the flange portion  31   a  is, for example, an annular plate protruding radially outward from the surface of the head portion  31 . The radial direction is parallel to a direction orthogonal to the axial direction. The surface of the flange portion  31   a  on the shaft portion  32  side in the axial direction is a seat surface  31 A that contacts the first washer  12  in a state where the fastening structure  10  is in a fastening state. The outer diameter of the seat surface  31 A is larger than the outer diameter of the end of the head  31 . 
     The shaft portion  32  is connected to an end surface of the head portion  31  on the flange portion  31   a  side. The outer diameter of the shaft  32  is smaller than the outer diameter of the end of the head  31 . The shaft portion  32  includes a screw portion  32   a  provided with a screw thread from the base portion on the head  31  side to the distal end portion in the axial direction. 
     The shaft portion  32  is inserted into the first washer  12 , the second washer  13 , and the through hole  21   c  of the first fixing member  21 . The shaft portion  32  is fastened and fixed to the second fixing member  22  by, for example, fitting the screw portion  32   a  to a female screw  22   c  of the second fixing member  22 . For example, the wall surface forming the through hole  21   c  of the first fixing member  21  is covered with an electrically insulating film  21   b . The female screw  22   c  of the second fixing member  22  is formed by a conductive main body  22   a , and the surface of the female screw  22   c  is exposed from the electrically insulating film  22   b.    
     The outer shape of the first washer  12  is, for example, a cylindrical shape having a bottom with a through hole formed therein. The first washer  12  is disposed with its bottom facing the opposite side of each of the fixing members  21  and  22 . The first washer  12  includes a conductive main body  41 , and a first seal portion  42  and a second seal portion  43  that are electrically insulating and cover a part of the main body  41 . 
     The outer shape of the main body  41  is, for example, an annular shape having an L-shaped cross section in the circumferential direction. The main body  41  includes a plate-shaped body  51 , a protruding portion  52 , and a radial protruding portion  53 . 
     The outer shape of the plate-shaped body  51  is, for example, an annular plate whose axial direction is the Z direction. The inner diameter of the plate-shaped body  51  is larger than the outer diameter of the shaft portion  32  and smaller than the outer diameter of the seat surface  31 A of the flange portion  31   a . The outer diameter of the plate-shaped body  51  is larger than the outer diameter of the seat surface  31 A of the flange portion  31   a . Part of the plate-shaped body  51  is sandwiched between the seat surface  31 A of the screw  11  and the second washer  13  from both sides in the axial direction in a state where the fastening structure  10  is in a fastening state. 
     The outer shape of the protruding portion  52  is, for example, a cylindrical shape whose axial direction is the Z direction. The protruding portion  52  protrudes in the thickness direction from the outer peripheral portion  51   a  of the plate-shaped body  51 . The thickness direction of the plate-shaped body  51  is parallel to the axial direction. 
     The outer shape of the radial protruding portion  53  is, for example, an annular plate whose axial direction is in the Z direction. The radial protruding portion  53  protrudes radially inward and outward from a distal end portion  52   a  of the protruding portion  52  in the axial direction. 
     The outer shape of the first seal portion  42  is, for example, a cylindrical shape in which both ends in the axial direction are bent radially outward. The first seal portion  42  is formed of an electrically insulating elastic material such as resin or rubber. The first seal portion  42  covers the inner peripheral surface  51 B of the inner peripheral portion  51   b  and both surfaces  51   b A and  51   b B in the thickness direction of the plate-shaped body  51 . The first seal portion  42  is sandwiched from both sides in the axial direction by the seat surface  31 A of the screw  11  and the second washer  13  in a state where the fastening structure  10  is in a fastening state. 
     The outer shape of the second seal portion  43  is, for example, an annular shape in which a concave groove is formed along the circumferential direction. The second seal portion  43  is formed of an electrically insulating elastic material such as resin or rubber. The second seal portion  43  covers at least the distal end portion  52   a  of the protruding portion  52  and the surface of the radial protruding portion  53 . The second seal portion  43  contacts the first fixing member  21  in a state where the fastening structure  10  is in a fastening state. 
     The second washer  13  is, for example, a chrysanthemum seat (toothed washer). The second washer  13  includes, for example, an annular plate-shaped portion  13   a  and a plurality of external teeth (an example of a tooth portion in the claims)  13   b.    
     The inner diameter of the annular plate-shaped portion  13   a  is larger than the outer diameter of the shaft portion  32  and smaller than the inner diameter of the first seal portion  42  of the first washer  12 . The annular plate-shaped portion  13   a  contacts the first seal portion  42  of the first washer  12  and the first fixing member  21  in a state where the fastening structure  10  is in a fastening state. 
     The plurality of external teeth  13   b  are arranged on the outer peripheral portion of the annular plate-shaped portion  13   a  at predetermined intervals along the circumferential direction. The outer diameter of the plurality of external teeth  13   b  is larger than the outer diameter of the first seal portion  42  of the first washer  12  and smaller than the inner diameter of the second seal portion  43  of the first washer  12 . 
     The plurality of external teeth  13   b  protrude radially outward from the outer peripheral portion of the annular plate-shaped portion  13   a , for example, while being alternately bent in different axial directions along the circumferential direction. Among the plurality of external teeth  13   b , an external teeth  13   b  that are bent toward the first washer  12  side in the axial direction come into contact with the plate-shaped body  51  of the first washer  12  in a state where the fastening structure  10  is in a fastening state. Among the plurality of external teeth  13   b , an external teeth  13   b  that are bent toward the first fixing member  21  side in the axial direction penetrate the coating  21   b  of the first fixing member  21  and come into contact with the main body  21   a  in a state where the fastening structure  10  is in a fastening state. 
     As shown in  FIGS. 1 and 3 , for example, the main body  22   a  of the second fixing member  22  is grounded. Since the first fixing member  21  and the second fixing member  22  are electrically insulated in the non-fastened state of the fastening structure  10 , the potential of the main body  21   a  of the first fixed member  21  is indefinite. 
     In the fastening state of the fastening structure  10 , the screw portion  32   a  of the screw  11  and the female screw  22   c  of the second fixing member  22  are brought into a conductive state by being fitted together. The screw  11  and the main body  22   a  of the second fixing member  22  have the same potential. The flange portion  31   a  of the screw  11  and the plate-shaped body  51  of the first washer  12  are brought into a conductive state by being in contact with each other. The screw  11  and the main body  41  of the first washer  12  have the same potential. 
     The plurality of external teeth  13   b  of the second washer  13  and the plate-shaped body  51  of the first washer  12  and the main body  21   a  of the first fixing member  21  are brought into a conductive state by being in contact with each other. The main body  41  of the first washer  12 , the second washer  13 , and the main body  21   a  of the first fixing member  21  have the same potential. The main bodies  21   a  and  22   a  of the first fixing member  21  and the second fixing member  22  are in a conductive state and the same potential through the screw  11 , the main body  41  of the first washer  12 , and the second washer  13 . 
     In the fastening state of the fastening structure  10 , the first seal portion  42  of the first washer  12  is sandwiched between the seat surface  31 A of the screw  11  and the second washer  13  from both sides in the axial direction. The space between the seat surface  31 A of the screw  11  and the second washer  13  is sealed by the first seal portion  42 . The second seal portion  43  of the first washer  12  contacts the first fixing member  21  radially outward from the second washer  13 . The space between the main body  41  of the first washer  12  and the first fixing member  21  is sealed by the second seal portion  43 . 
     According to the embodiment described above, by providing the first washer  12  having the bottomed cylindrical shape, it is possible to arrange the second washer  13  for conduction between the plate-shaped body  51  and the first seal portion  42  of the first washer  12  and the first fixing member  21 . The first washer  12  can make the flange portion  31   a  of the screw  11  and the main body  21   a  of the first fixing member  21  brought into a conductive state and have the same potential via the second washer  13 . The shaft portion  32  of the screw  11  is fitted to the female screw  22   c  of the second fixing member  22 . Thereby, the main body  21   a  of the first fixing member  21  and the main body  22   a  of the second fixing member  22  can be brought into a conductive state and have the same potential. 
     The first washer  12  can secure desired sealing properties between the flange portion  31   a  of the screw  11  and the second washer  13  and the first fixing member  21  by the first seal portion  42  and the second seal portion  43 . 
     The first washer  12  has a radial protruding portion  53  that protrudes radially from a distal end portion  52   a  of the protruding portion  52  in the axial direction. Therefore, for example, the contact area between the second seal portion  43  and the first fixing member  21  can be increased as compared with the case where the radial protruding portion  53  is not provided. The radial protruding portion  53  can improve the sealing performance between the second seal  43  and the first fixing member  21 . 
     The second washer  13  is provided to have the external teeth  13   b  penetrating the coating  21   b  of the first fixing member  21  and contacting the conductive body  21   a  and the external teeth  13   b  contacting the conductive plate-shaped body  51  of the first washer  12 . Thereby, the conductive state between the screw  11  and the first fixing member  21  can be easily and accurately secured. 
     Hereinafter, modified examples will be described. 
     In the embodiment described above, the head  31  of the screw  11  is provided with the flange portion  31   a , but it is not limited thereto and the flange portion  31   a  may be omitted. In this case, the outer diameter of the seat surface of the head  31  is set to be larger than the inner diameter of the plate-shaped body  51  of the first washer  12 . 
     In the above-described embodiment, the screw  11  is fastened and fixed to the second fixing member  22  by fitting the screw portion  32   a  to the female screw  22   c  of the second fixing member  22 , but it is not limited thereto. The screw  11  may be fixed to the second fixing member  22  by, for example, fitting the screw portion  32   a  to a conductive nut or the like that is in electrical contact with the main body  22   a  of the second fixing member  22 . 
     In the embodiment described above, the main body  41  of the first washer  12  is provided with the radial protruding portion  53 , but the present invention is not limited thereto and the radial protruding portion  53  may be omitted. 
     According to at least one embodiment described above, by having the bottomed cylindrical first washer  12 , it is possible to arrange the second washer  13  for conduction between the plate-shaped body  51  and the first seal portion  42  of the first washer  12  and the first fixing member  21 . The first washer  12  can make the flange portion  31   a  of the screw  11  and the main body  21   a  of the first fixing member  21  brought into a conductive state and have the same potential via the second washer  13 . 
     Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof. 
     REFERENCE SIGNS LIST 
       10 : Fastening structure,  11 : Screw,  12 : First washer (Washer),  13 : Second washer (Annular member),  13   b : External teeth (Tooth portion),  21 : First fixing member,  21   b ,  22   b : Coating (Coating layer),  22 : Second fixing member,  31 : Head,  31   a : Flange portion,  31 A: Seat surface,  32 : Shaft portion,  32   a : Screw portion,  41 : Body,  42 : First seal portion,  43 : Second seal portion,  51 : Plate-shaped body,  51   a : Outer peripheral portion,  51   b : Inner peripheral portion,  51 B: Inner peripheral surface,  51   b A,  51   b B: Both surfaces,  52 : Protruding portion,  52   a : Distal end portion,  53 : Radial protruding portion