Patent Publication Number: US-2022221058-A1

Title: Sealing device

Description:
TECHNICAL FIELD 
     The present invention relates to a sealing device. 
     BACKGROUND ART 
     Conventionally, it is known that a gasket acts as a sealing device that is attached to an annular space like an annular groove formed between a plurality of members, such as a housing and a cover, placed face-to-face and immobilized relative to each other, to seal the annular space. Such a gasket and a plurality of members forming an annular space to which the gasket is attached make up a sealing structure. The gasket as described above including a tubular reinforcing ring formed annularly around an axis and extending in a direction of the axis and an elastic body part formed from an elastic body that is attached to the reinforcing ring is disclosed. In the gasket, the elastic body part includes a pair of lip portions each extending along the axis from both end portions of the reinforcing ring in the direction of the axis (for example, see Patent Literature 1). 
     In recent years, in response to reductions in size or weight of a component to which the gasket is applied, a cross section of the gasket has been made smaller due to downsizing of the gasket and the component to which the gasket is applied has been developed to be made thinner or to be made of resin. The smaller cross section of the gasket and the development of the component to which the gasket is applied being made thinner or being made of resin decrease a size of the annular space to which the gasket is attached and increase a degree of relative variation in the size of the space caused by manufacturing. As a result, it is conceivable that a gasket cannot provide intended sealing performance because of the variation in the size of the annular space to which the gasket is attached and thus techniques have been disclosed to resolve such a problem (for example, see Patent Literature 2). 
     DOCUMENT LIST 
     Patent Literatures 
     
         
         Patent Literature 1: Japanese Utility Model Laid-Open No. 6-32834 
         Patent Literature 2: International Publication No. WO 2015/137491 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     If the component to which the gasket is applied is a pipe that constitutes, for example, a hydraulic passage, the gasket receives pressure (internal pressure) from the hydraulic passage on an inner periphery side of the gasket. Thus, in general, the gasket for the pipe of the hydraulic passage is held in an annular groove formed in an inner periphery side of the pipe, as disclosed in the technique of Patent Literature 1, to prevent the gasket from being displaced by the internal pressure in a radial direction perpendicular to the direction of the axis. 
     Unfortunately, the conventional gasket as disclosed in Patent Literature 1 necessitates forming a groove in the inner periphery side of the pipe. Hence, the conventional gasket cannot be applied to a pipe that is, for example, thin in thickness and makes it difficult to form a groove. 
     In view of the problems described above, it is an object of the present invention to provide a sealing device that can possess improved attachability to a component to which the sealing device is applied. 
     Solution to Problem 
     A sealing device according to the present invention, accomplished to attain the object described above, is for sealing an annular space formed by a plurality of members, the sealing device including: a reinforcing ring formed annularly around an axis; and an elastic body part that is formed from an elastic body attached to the reinforcing ring and that is formed annularly around the axis, the reinforcing ring including: a tubular portion having a cylindrical shape around the axis; and a flange projecting annularly from an outer end portion of the tubular portion to an inner periphery side, wherein the elastic body part includes a lip portion that is an annular portion covering the flange from an outer side, projecting from the flange toward the outer side in a direction of the axis, and projecting toward the inner periphery side in a radial direction, the lip portion including: a seal lip portion that is an annular portion projecting toward the outer side in the direction of the axis; and a secondary lip portion that is an annular portion projecting toward an inner side in the direction of the axis. 
     In the sealing device according to one aspect of the present invention, the tubular portion has a tubular-portion inner peripheral surface on the inner periphery side, the flange has a flange inner side surface on the inner side, the tubular-portion inner peripheral surface enables the sealing device to be positioned relative to the plurality of members in the radial direction, and the flange inner side surface enables the sealing device to be positioned relative to the plurality of members in the direction of the axis. 
     In the sealing device according to one aspect of the present invention, the elastic body part includes an inner peripheral portion covering the tubular-portion inner peripheral surface from the inner periphery side. 
     In the sealing device according to one aspect of the present invention, the plurality of members include at least a cylindrical member, the tubular-portion inner peripheral surface enables the sealing device to be positioned in the radial direction by allowing the sealing device to be in contact with an outer peripheral portion included in the cylindrical member, and the flange inner side surface enables the sealing device to be positioned in the direction of the axis by allowing the sealing device to be in contact with an outer side surface formed on the cylindrical member. 
     In the sealing device according to one aspect of the present invention, the seal lip portion projects to the outer side with respect to the flange in the direction of the axis, and the secondary lip portion projects to the inner side with respect to the flange in the direction of the axis. 
     In the sealing device according to one aspect of the present invention, a length of the seal lip portion in the direction of the axis is greater than a length of the secondary lip portion in the direction of the axis. 
     Effects of Invention 
     The sealing device according to the present invention can possess improved attachability to a component to which the sealing device is applied. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  A bottom view for illustrating a schematic configuration of a sealing device according to a first embodiment of the present invention. 
         FIG. 2  A cross-sectional view of the sealing device illustrated in  FIG. 1  taken from cross section A-A along an axis. 
         FIG. 3  A schematic view of the sealing device illustrated in  FIG. 1  and an attachment space to which the sealing device is attached taken from a cross section along an axis to illustrate a difference in shape between the sealing device and the attachment space. 
         FIG. 4  A cross-sectional view illustrating the sealing device illustrated in  FIG. 1  in a usage state. 
         FIG. 5  A cross-sectional view illustrating a sealing device according to a reference example in a usage state taken along an axis. 
         FIG. 6  A cross-sectional view illustrating the sealing device according to the reference example illustrated in  FIG. 5  in another usage state taken along an axis. 
         FIG. 7  A cross-sectional view illustrating the sealing device illustrated in  FIG. 1  in a modification example of a usage state taken along an axis. 
         FIG. 8  A bottom view for illustrating a schematic configuration of a sealing device according to a second embodiment of the present invention. 
         FIG. 9  A perspective cross-sectional view of the sealing device illustrated in  FIG. 8  taken from cross section B-B along an axis. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     First Embodiment 
       FIG. 1  is a bottom view for illustrating a schematic configuration of a sealing device  1  according to a first embodiment of the present invention.  FIG. 2  is a cross-sectional view of the sealing device  1  taken from cross section A-A along an axis x. 
     Hereinafter, a direction directed by an arrow a in a direction of the axis x (one side in the direction of the axis, see  FIG. 2 ) represents an outer side, and a direction directed by an arrow b in the direction of the axis x (another side in the direction of the axis, see  FIG. 2 ) represents an inner side, for convenience of explanation. In a direction perpendicular to the axis x (hereinafter also referred to as a “radial direction”), a direction away from the axis x (a direction directed by an arrow c in  FIG. 2 ) represents an outer periphery side, and a direction approaching the axis x (a direction directed by an arrow d in  FIG. 2 ) represents an inner periphery side. 
     As illustrated in  FIGS. 1 and 2 , the sealing device  1  according to the first embodiment of the present invention includes a reinforcing ring  10  formed annularly around the axis x and an elastic body part  20  that is formed from an elastic body attached to the reinforcing ring  10  and that is formed annularly around the axis x. The reinforcing ring  10  includes a tubular portion  14  having a cylindrical shape around the axis x and a flange  15  projecting annularly from an outer end portion of the tubular portion  14  to an inner periphery side d. The elastic body part  20  includes a lip portion  21  that is an annular portion covering the flange  15  from an outer side a, projecting from the flange  15  toward the outer side a in the direction of the axis x, and projecting toward the inner periphery side d in the radial direction. The lip portion  21  includes a seal lip portion  22  that is an annular portion projecting toward the outer side a in the direction of the axis x and a secondary lip portion  23  that is an annular portion projecting toward an inner side b in the direction of the axis x. Hereinafter, the sealing device  1  will be described in detail. 
     As illustrated in  FIG. 2 , the reinforcing ring  10  is a tubular or substantially tubular member extending along the axis x. The reinforcing ring  10  is, for example, a cylindrical or substantially cylindrical member centered about or substantially centered about the axis x. The reinforcing ring  10 , as described above, includes the tubular portion  14  and the flange  15 . The tubular portion  14  has a cylindrical or substantially cylindrical surface formed around the axis x. The tubular portion  14  has a reinforcing-ring inner side end  11  that is formed on an end portion on the inner side b and a reinforcing-ring outer side end  12  that is an end portion on the outer side a. The tubular portion  14  has a tubular-portion inner peripheral surface  14   a  that is a surface on the inner periphery side d. 
     The flange  15  annularly projects toward the inner periphery side d from the reinforcing-ring outer side end  12 , an end portion on the outer side a of the tubular portion  14 . The flange  15  has a reinforcing-ring inner peripheral end  16  that is an end portion on the inner periphery side d. The flange  15  has a flange inner side surface  15   a  that is a surface on the inner side d. 
     The reinforcing ring  10  is a part used to reinforce the elastic body part  20 . The tubular portion  14  and the flange  15  of the reinforcing ring  10  are formed, for example, by bending a metal material. The metal material used in the reinforcing ring  10  is, for example, stainless steel or SPCC (a cold rolled steel sheet). If the reinforcing ring  10  is made of a resin material, the resin material used in the reinforcing ring is, for example, nylon 66 (PA66) or a polyphenylene sulfide (PPS) resin. 
     The elastic body part  20  is formed so as to cover the reinforcing ring  10 . The elastic body part  20 , as described above, has the lip portion  21 , as well as the seal lip portion  22 , the secondary lip portion  23 , an outer peripheral portion  24 , and a base portion  25 . The outer peripheral portion  24  covers a surface on an outer periphery side c of the tubular portion  14 . The tubular portion  14  is formed annularly in the reinforcing ring  10 . The base portion  25  covers a part at the inner periphery side d of the outer peripheral portion  24 , i.e., a surface on the inner periphery side d of the tubular portion  14 . A portion of the base portion  25  facing the inner periphery side d is an inner peripheral portion  25   a . The inner peripheral portion  25   a  covers the tubular-portion inner peripheral surface  14   a  from the inner periphery side d. 
       FIG. 3  is a schematic view of the sealing device  1  and an attachment space S to which the sealing device  1  is attached taken from a cross section along an axis x 1  to illustrate a difference in shape between the sealing device  1  and the attachment space S. In  FIG. 3 , the sealing device  1  and the attachment space S to which the sealing device  1  is attached overlap in the cross section along the axis x 1  to schematically illustrate a difference in shape and size between the sealing device  1  and the attachment space S. As illustrated in  FIG. 3 , regarding the sealing device  1 , a length of the elastic body part  20  including the lip portion  21 , the seal lip portion  22 , the outer peripheral portion  24 , and the base portion  25  is longer than a length of the attachment space S in a direction of the axis x 1 . 
     As illustrated in  FIG. 2 , the outer peripheral portion  24  is a portion covering the reinforcing ring  10  from the outer periphery side c. The outer peripheral portion  24  has an outer-peripheral outer side end  24   a , an end portion on the outer side a, that is joined to the lip portion  21 . The outer peripheral portion  24  is formed such that an outer-peripheral inner side end  24   b , an end portion on the inner side b, covers the reinforcing-ring inner side end  11  of the tubular portion  14 . The outer peripheral portion  24  has an edge (a corner) formed on the outer periphery side c in the vicinity of the outer-peripheral inner side end  24   b . The outer-peripheral inner side end  24   b  is defined by an annular surface facing the inner side b and an outer peripheral surface portion  24   d  that is a tubular surface facing the outer periphery side c. 
     As illustrated in  FIG. 2 , the base portion  25  covers the tubular portion  14  of the reinforcing ring  10  from the inner periphery side d. An end portion on the outer side a of the base portion  25  is joined to the lip portion  21 . The base portion  25  is formed such that the inner peripheral portion  25   a  on the inner periphery side d covers the tubular-portion inner peripheral surface  14   a  of the tubular portion  14  from the inner periphery side d. In other words, in the sealing device  1 , the inner peripheral portion  25   a  of the base portion  25  is formed annularly around the axis x. 
     The lip portion  21  is disposed so as to cover the flange  15  of the reinforcing ring  10  from the outer side a. The lip portion  21  is formed annularly around the axis x. In the lip portion  21 , a lip body  211 , the seal lip portion  22 , and the secondary lip portion  23  are disposed. 
     The lip body  211  is formed so as to extend from the outer peripheral portion  24  and the base portion  25  of the elastic body part  20  toward the outer side a. The lip body  211  is, for example, formed such that an outer peripheral surface portion  21   a , a surface on the outer periphery side c, is flush with the outer peripheral surface portion  24   d  of the outer peripheral portion  24 . The lip body  211  is formed such that a surface on the outer side a of the lip body is parallel to or substantially parallel to a surface on the outer side a of the flange  15 . The elastic body part includes the seal lip portion  22  and the secondary lip portion  23  on the inner periphery side d of the lip body  211 . An inner peripheral surface portion  21   b  is formed between the seal lip portion  22  and the secondary lip portion  23  on the inner periphery side d of the lip body  211 . The secondary lip portion  23  is formed so as to extend from an end portion on the inner periphery side d of the lip body  211  to the inner side b in the direction of the axis. 
     The seal lip portion  22  projects diagonally from the end portion on the inner periphery side d of the lip body  211  toward the outer side a and the inner periphery side d. The seal lip portion  22  is, for example, a portion that increases in diameter as progress toward the inner side b (that decreases in diameter as progress toward the outer side a) in the direction of the axis x. An extent to which the seal lip portion  22  increases in diameter is not particularly limited. The seal lip portion  22  is a conical cylindrical or substantially conical cylindrical portion centered about or substantially centered about the axis x. The seal lip portion  22  projects to the outer side a with respect to the reinforcing-ring outer side end  12  and the flange  15 . A seal-lip distal end  22   a  that is an end portion on the outer side a of the seal lip portion  22  is positioned on the outer side a with respect to the reinforcing-ring outer side end  12  and the flange  15  in the direction of the axis x. The elastic body part  20  of the sealing device  1  may be formed so as to increase in diameter as progress from the lip body  211  toward the seal-lip distal end  22   a . An extent to which the elastic body part  20  of the sealing device  1  increases or decreases in diameter as progress from the lip body  211  toward the seal-lip distal end  22   a  may be constant or may vary place by place. The seal-lip distal end  22   a  is thinner than a seal-lip root  22   b  that is a portion joined to the lip body  211 . The seal lip portion  22  may increase in thickness as progress from the seal-lip root  22   b  toward the seal-lip distal end  22   a , for example. 
     The seal lip portion  22  projects in a direction of the outer side a that is a direction, indicated by an arrow O 1  in  FIG. 3 , in which the sealing device comes off in a sealing structure where the sealing device  1  is attached. The seal-lip distal end  22   a  of the seal lip portion  22  projects to the outer side a with respect to the reinforcing ring  10  and the surface on the outer side a of the lip body  211  in a direction of an axis x 1 . The seal lip portion  22  projects to the inner periphery side d with respect to the reinforcing ring  10  and the lip body  211  in the radial direction. In other words, the seal lip portion  22  has a length and an outer peripheral surface so as to be in contact with an outer-side sealing surface  102   a , a sealing surface on the outer side a, with a predetermined interference in a usage state described later. Note that the length of the seal lip portion  22  is a width in a direction of extension (a direction of projection, the direction of the outer side a in  FIG. 3 ) of the seal lip portion  22 . 
     As illustrated in  FIG. 2 , the secondary lip portion  23 , for example, projects diagonally from a place on the inner side b of the end portion on the inner periphery side d of the lip body  211  toward the inner side b and the inner periphery side d. Specifically, the secondary lip portion  23  is a portion that decreases in diameter as progress toward the inner side b in the direction of the axis x. The secondary lip portion  23  is a conical cylindrical or substantially conical cylindrical portion centered about or substantially centered about the axis x. The secondary lip portion  23  projects to the inner side b with respect to the reinforcing-ring inner peripheral end  16  on the inner side b of the flange  15 . A secondary-lip distal end  23   a  is an end portion on the inner side b of the secondary lip portion  23 . The secondary-lip distal end  23   a  is positioned on the inner side b with respect to the lip portion  21  and the flange  15  in the direction of the axis x. The secondary-lip distal end  23   a  is thinner than a secondary-lip root  23   b  that is a portion joined to the base portion  25 . The secondary lip portion  23 , for example, extends from the lip body  211  toward the inner side b and the inner periphery side d. The secondary lip portion  23  decreases in thickness as progress from the secondary-lip root  23   b  toward the secondary-lip distal end  23   a . The secondary lip portion  23  has a length so as to be in contact with a pipe end portion  122  on the outer side a of a pipe  120 , a sealing surface on the inner side b, with a predetermined interference in the usage state described later. The secondary lip portion  23  is short in an amount of projection (a length of a projecting part) in the direction of the axis x as compared to the seal lip portion  22 . The secondary lip portion  23  is also short in a dimension in the radial direction as compared to the seal lip portion  22 . In other words, a total volume of the secondary lip portion  23  formed into a conical cylinder or a substantially conical cylinder is small as compared to that of the seal lip portion  22 . 
     As illustrated in  FIG. 2 , the elastic body part  20  may not cover the flange inner side surface  15   a  on the inner side b of the flange  15 . The elastic body part  20  may be flush with the flange inner side surface  15   a  in the direction of the axis x. The elastic body part  20  may not be flush with the flange inner side surface  15   a  in the direction of the axis x. The elastic body part  20  may cover the flange inner side surface  15   a . In this case, the elastic body part  20  is formed such that the secondary-lip distal end  23   a  is positioned on the inner side b with respect to a part of the elastic body part  20  covering the flange inner side surface  15   a  in the direction of the axis x. 
     Examples of the elastic body of the elastic body part  20  include various rubber materials. The various rubber materials are, for example, synthetic rubber such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM). 
     The reinforcing ring  10  is manufactured by press working or forging, for example. The elastic body part  20  is molded with a mold by cross-linking (vulcanization). During the cross-linking, the reinforcing ring  10  is placed in the mold. The elastic body part  20  is bonded to the reinforcing ring  10  by cross-linking bonding, and the elastic body part  20  is integrally molded with the reinforcing ring  10 . 
     Thereafter, the sealing device  1  in the usage state described above will be described. 
       FIG. 4  is a cross-sectional view illustrating the sealing device  1  in a usage state. As illustrated in  FIG. 4 , the sealing device  1  gets into the usage state when the sealing device is attached to an attachment space S, an annular space. The attachment space S is an annular or substantially annular space that is formed around an axis x 1  by a plurality of members. The attachment space S is, for example, formed by a housing  110  and the pipe  120 , a cylindrical member. The housing  110  has a through-hole  111 , and the pipe  120  has a through-hole  121  communicating with the through-hole  111  of the housing  110 . The pipe  120  has the pipe end portion  122 , a pipe inner peripheral surface  123 , and a pipe surface  124 . The pipe surface  124  is annular around the axis x 1  and is exposed to the outer periphery side c. The pipe end portion  122  is annular in the radial direction. The pipe inner peripheral surface  123  faces the inner periphery side d and is formed around the axis x 1 . In the attachment space S, a space is formed between the housing  110  and the pipe  120  to only allow the sealing device  1  to be interposed between the members. 
     The housing  110  is disposed such that a housing surface  112   a  of the housing faces the pipe end portion  122  of the pipe  120 . The housing  110  is configured such that the through-hole  111  of the housing is coaxial or substantially coaxial with respect to the through-hole  121  of the pipe  120 . Thus, the through-hole  111  and the through-hole  121  communicate to form a single through-tube  130 . The housing surface  112   a  is an annular flat surface facing the pipe end portion  122  of the pipe  120  in the direction of the axis x 1 . In the housing  110 , the housing surface  112   a  is an outer-side sealing surface. The attachment space S is an annular space defined by the above-described housing surface  112   a  and the pipe end portion  122  and the pipe inner peripheral surface  123  of the pipe  120 . The sealing device  1  in the attachment space S seals the through-tube  130  formed by a through-hole  101  and the through-hole  111 . In the attachment space S, the inner peripheral surface portion  21   b  of the lip portion  21  of the sealing device  1  faces the through-tube  130 . In the through-tube  130 , pressure (internal pressure P 1 ) is exerted from the inner periphery side d toward the outer periphery side c. 
     In the usage state, the sealing device  1  is attached to the pipe end portion  122  of the pipe  120  coaxially or substantially coaxially with respect to the through-tube  130 . In other words, in the usage state, the axis x of the sealing device  1  illustrated in  FIG. 2  and the axis x 1  coincide with or slightly diverge from each other. 
     As illustrated in  FIGS. 3 and 4 , the inner peripheral portion  25   a  of the base portion  25  centered about and formed annularly around the axis x 1  at the inner periphery side d of the tubular-portion inner peripheral surface  14   a  is in contact with the pipe surface  124 , an outer side surface of the pipe  120 , across a range indicated by an arrow O 2  in the direction of the axis x. In other words, the tubular-portion inner peripheral surface  14   a  formed in the sealing device  1  allows the sealing device to be put into contact with the pipe surface  124 , an outer peripheral portion of the pipe  120 , and movement of the sealing device in the radial direction is restricted by an inside diameter of the tubular-portion inner peripheral surface  14   a . This configuration enables the sealing device to be positioned in the radial direction. 
     The flange inner side surface  15   a  is in contact with the pipe end portion  122  of the pipe  120 . The secondary lip portion  23  is pressed by the pipe end portion  122  of the pipe  120  and is in contact with the pipe end portion  122  with a predetermined interference or squeeze. In other words, in the sealing device  1 , the flange inner side surface  15   a  of the reinforcing ring  10  and the secondary lip portion  23  of the elastic body part  20  are disposed. The members formed in this way allows the sealing device  1  to be put into contact with the pipe end portion  122 , a surface on the outer side a of the pipe  120 , and movement of the sealing device in the direction of the axis x is restricted. This configuration enables the sealing device to be positioned in the direction of the axis x. 
       FIG. 5  is a cross-sectional view of a sealing device  2  according to a reference example taken along an axis x.  FIG. 6  is a cross-sectional view of the sealing device  2  according to the reference example taken along the axis x. 
     As illustrated in  FIGS. 5 and 6 , in the sealing device  2  according to the reference example, a reinforcing ring  214  does not include a tubular portion  14  and a flange  15  unlike the sealing device  1 . In the sealing device  2  according to the reference example, an elastic body part  220  does not include a lip portion  21  projecting from a reinforcing ring  10  toward the outer side a in the direction of the axis x unlike the sealing device  1 . 
     In the sealing device  2 , the reinforcing ring  214  does not include the tubular portion  14  and the flange  15  unlike the sealing device  1 . This necessitates forming a groove  228  with an increased diameter in the inner periphery side d of a pipe  320  to which the sealing device  2  is attached to hold the sealing device  2  from the outer periphery side c. 
     As illustrated in  FIG. 6 , a sealing device  2 B is configured in a similar way to the sealing device  2 . Thus, in some cases, an inner peripheral wall part  328   b  is inevitably thin in thickness depending on a dimension and a thickness of the pipe  320  in the radial direction, and this makes it difficult to provide a groove  328 . 
     Meanwhile, as described above, the sealing device  1  is designed to be positioned in the radial direction by the tubular-portion inner peripheral surface  14   a  of the reinforcing ring  10  and the inner peripheral portion  25   a  of the base portion  25  of the elastic body part  20  and is designed to be positioned in the direction of the axis x by the flange inner side surface  15   a  and the secondary lip portion  23 . As a result, the sealing device  1  can be, for example, attached to even a pipe  120  that is thin in thickness and makes it difficult to form a groove without formation of a groove in the inner periphery side d of the pipe. 
     Thus, the sealing device  1  can possess improved attachability to a component to which the sealing device is applied. 
     In the sealing device  1 , the seal lip portion  22  and the secondary lip portion  23  of the lip portion  21  are formed from the elastic body part  20 , which is a single elastic body. Here, the secondary lip portion  23  projecting to the inner side b in the direction of the axis x is smaller than the seal lip portion  22  projecting to the outer side a in the direction of the axis x. As a result, in the lip portion  21 , the secondary lip portion  23  is low in rigidity and can readily deform compared to the seal lip portion  22 . In other words, the secondary lip portion  23  deforms positively when being compressed by an external force or when receiving the internal pressure P 1  from the through-tube  130  toward the outer periphery side c. In this way, the secondary lip portion  23  deforms positively and the flange inner side surface  15   a  is thereby put into contact with the pipe end portion  122  of the pipe  120 . This enables the sealing device  1  to be positioned in the direction of the axis x. 
     The lip portion  21  configured as described above enables the sealing device  1  to inhibit posture deformation caused by the internal pressure P 1  and thus provide stable sealing performance. The lip portion  21  configured as described above enables the sealing device  1  to offset a difference (a variation) in a size of the attachment space S by the seal lip portion  22  having a large size. Further, the lip portion  21  configured as described above enables the sealing device  1  to inhibit the tubular-portion inner peripheral surface  14   a  and the inner peripheral portion  25   a  from moving to the outer side a in the direction of the axis x and being detached from the pipe surface  124  of the pipe  120 . This prevents the sealing device  1  from coming off. 
     As described above, the sealing device  1  according to the first embodiment of the present invention can possess improved attachability to a component such as the pipe  120  to which the sealing device is applied. 
       FIG. 7  is a cross-sectional view illustrating the sealing device  1  in a modification example of a usage state taken along an axis. Unlike the sealing device in an example of the usage state illustrated in  FIG. 3 , the sealing device  1 , as illustrated in  FIG. 7 , is attached such that the inner peripheral portion  25   a  of the base portion  25  of the elastic body part  20  is in contact with a pipe inner peripheral surface  123 B of a pipe  120 B and the inner peripheral surface portion  21   b  of the lip portion  21  faces the outer periphery side c of the attachment space S. Being attached in this way, the sealing device  1  can also be applied to a component to seal the component against pressure (external pressure P 2 ) from the outer periphery side c. 
     Second Embodiment 
     Thereafter, a sealing device  1 C according to a second embodiment of the present invention will be described. Hereinafter, components of the sealing device  1 C that are identical or similar in function to those of the sealing device  1  according to the first embodiment described above are assigned the same reference signs, and descriptions thereof are omitted. Only components that differ between the sealing devices will be described. 
       FIG. 8  is a bottom view for illustrating a schematic configuration of the sealing device  1 C according to the second embodiment of the present invention.  FIG. 9  is a perspective cross-sectional view of the sealing device  1 C taken from cross section B-B along an axis x. 
     As illustrated in  FIGS. 8 and 9 , in the sealing device  1 C, protrusions  25   b C each projecting toward the inner periphery side d may be formed on an inner peripheral portion  25   a C of a base portion  25 C. The inner peripheral portion  25   a C faces the inner periphery side d and covers a tubular-portion inner peripheral surface  14   a  from the inner periphery side d. When the sealing device  1 C is in a usage state, the protrusions  25   b C are in contact with a pipe surface of a pipe. The protrusions  25   b C position the sealing device relative to the pipe surface in the radial direction. With the protrusions  25   b C formed on the inner peripheral portion  25   a C, the sealing device  1 C is kept from coming off in the usage state. The other components of the sealing device  1 C are similar to those of the sealing device  1  described above. 
     In a similar way to the sealing device  1  described above, the sealing device  1 C according to the second embodiment can possess improved attachability to a component to which the sealing device is applied. 
     Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments of the present invention, and includes any modes falling within the scope of the concept and claims of the present invention. Respective configurations may be appropriately selectively combined to solve at least part of the above-described problems and achieve at least part of the above-described effects. For example, in the above-described embodiments, the shape, material, arrangement, size and the like of each component can be appropriately changed according to a specific use mode of the present invention. 
     LIST OF REFERENCE SIGNS 
     
         
           1  sealing device, 
           10  reinforcing ring, 
           11  reinforcing-ring inner side end, 
           12  reinforcing-ring outer side end, 
           14  tubular portion, 
           14   a  tubular-portion inner peripheral surface, 
           15  flange, 
           15   a  flange inner side surface, 
           16  reinforcing-ring inner peripheral end, 
           20  elastic body part, 
           21  lip portion, 
           21   a  outer peripheral surface portion, 
           21   b  inner peripheral surface portion, 
           22  seal lip portion, 
           22   a  seal-lip distal end, 
           22   b  seal-lip root, 
           23  secondary lip portion, 
           23   a  secondary-lip distal end, 
           23   b  secondary-lip root, 
           24  outer peripheral portion, 
           24   a  outer-peripheral outer side end, 
           24   b  outer-peripheral inner side end, 
           24   d  outer peripheral surface portion, 
           25 ,  25 C base portion, 
           25   a ,  25   a C inner peripheral portion, 
           25   b C protrusion, 
           101  through-hole, 
           102   a  outer-side sealing surface, 
           110  housing, 
           111  through-hole, 
           112   a  housing surface, 
           120  pipe, 
           121  through-hole, 
           122  pipe end portion, 
           123  pipe inner peripheral surface, 
           124  pipe surface, 
           130  through-tube