Abstract:
A seal device includes a first resilient seal ring having a first resilient seal portion and first and second seal portions; and a second resilient seal ring. The first resilient seal portion urges a first seal surface of the first seal ring against the second seal surface of the second seal ring. The second seal portion mates with the first retainer portion of the first seal ring, while the first seal portion is in a sealing relation with one component. The second resilient seal ring has a second resilient seal portion, and first and second seal portions. The second resilient seal portion urges a second seal surface of the second seal ring against the first seal surface of the first seal ring, while the second seal portion mates with the second retainer portion of the second seat ring.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a seal device disposed between a pair of relatively rotating elements typically seen in the rollers of a crawler, track roller, reduction gear, hydraulic motor or the like. More particularly, the invention relates to a seal device in the reduction gear unit of automobiles or hydraulic motors of a variety of machinery, which provides an effective seal at the interface of relatively moving elements against a process fluid containing slurry or a high pressure process fluid. 
   2. Description of the Related Art 
   Primary related art of the present invention is found as a seal ring in U.S. Pat. No. 6,086,069. A similar type of seal ring as the one shown in U.S. Pat. No. 6,086,069 is illustrated, for example, in FIG. 8. The seal ring  101  in  FIG. 8  is, for example, mounted to a crawler unit  100 . 
   In  FIG. 8 ,  120  represents a shaft. The shaft  120  is disposed within a through bore of a roller  125 , and a ring seal  101  is disposed in the chamber formed between the shaft  120  and the roller  125 . The ring seal  101  provides a seal by preventing dusty water or muddy fluid from entering. 
   In this ring seal  101 , a primary resilient ring  102  has an annularly shaped body whose cross section is “J”-shaped and outer surface forms a curved concave face  105 . One end face of the primary resilient ring  102  is defined as outer fitting face  102 A while the other end face is defined as inner fitting face  102 B. Likewise, a secondary resilient ring  103  has also an annularly shaped body whose cross section is “J”-shaped and outer surface forms a curved concave face  105 . Therefore one end face of the secondary resilient ring  103  defines outer fitting face  103 A while the other end face defines inner fitting face  103 B. 
   Next a first seal ring  110  has an annularly shaped body whose cross section is “U”-shaped and its radially extending end face of the first seal ring  110  defines a seal face  110 A. An annular groove of the seal ring  110  which is located on the other side of the seal face  110 A defines a mount groove portion  110 B. Likewise, a second seal ring  111  has an annularly shaped body whose cross section is also “U”-shaped and its radially extending end face of the second seal ring  111  defines a mating seal face  111 A. An annular groove disposed on the other side of the seal face  111 A then defines a mount groove portion  111 B. 
   The first resilient ring  102  and the second resilient ring  103  thus constructed as well as the first seal ring  110  and the second seal ring  111  are all installed within the chamber formed between the shaft  120  and the roller  125 , as depicted in  FIG. 8 . Therefore the first resilient ring  102  and the second resilient ring  103  retain curved concave surfaces  105 ,  105  relative to an ambient passage chamber  126 . Also the first resilient ring  102  and the second resilient ring  103  possess curved convex surfaces relative to a lubricant-filled internal chamber  127 . The first resilient ring  102  exerts a resiliently urging force such that the seal surface  110 A of the first seal ring  110  is pressed against the second seal ring  103 . The opposed seal surfaces  110 A and  111 A being pressed against each other provide an effective seal for the process fluid coming into the ambient passage chamber  126 . 
   In addition a floating seal device  150  shown in  FIG. 9  is the second prior art related to the current invention. This floating seal device  150  include a first seal ring  152  and a second seal ring  153  which are disposed around the shaft in axially symmetric a manner. A seal surface  152 A of the first seal ring  152  and a seal surface  153 A of the second seal ring  153  therein exhibit a seal-tight joint. Such a joint between the seal surface  152 A of the first seal ring  152  and the seal surface  153 A of the second seal ring  153  is achieved by the resiliently urging forces due to compressed rubber materials as shown by the elliptic cross sections used for a first O-ring  155  and a second O-ring  156 . For that purpose, the first O-ring  155  and the second O-ring  156  are disposed, respectively, between a housing and the first seal ring  152  and the housing and the second seal ring  153  such that the elliptic cross section forms an angle to the radial direction. 
   A first seal face  155 A of the first O-ring  155  and a first seal face  156 A of the second O-ring  156  individually form a sealing contact with the housing while a second seal face  155 B of the first O-ring  155  and a second seal face  156 B of the second O-ring  156 , respectively, make a sealing contact with the first seal ring  152  and the second seal ring  153 . However, the degree of the sealing contact at the seal surfaces  152 A and  153 A urged by the first O-ring  155  and the second O-ring  156  relies on the reaction force of the compressed rubber materials. Therefore a choice of hardness in rubber materials may vary and it makes difficult to make an optimal decision of rubber materials. 
   This floating seal device  150  provides a seal for a process fluid containing slurry. It can also be applied to a fluid containing fine particles. The first O-ring  155  and the second O-ring  156  which are resiliently compressed and disposed in a symmetric manner, respectively, provide urging forces to the first seal ring  152  and the second seal ring  153  so that a sealing contact is made between the opposed seal surfaces  152 A and  153 A. Therefore the fact that the elastic reaction forces due to the rubber materials of the first O-ring  155  and the second O-ring  156  is the source of the sealing contact at the seal surfaces  152 A and  153 A will lead to an acceleration of abrasion of the seal surfaces  152 A and  153 A caused by large urging forces. 
   In addition if slurry particles or as such are trapped at the joint surface between the first O-ring  155  and the first seal ring  152  or the second O-ring  156  and the second seal ring  153 , the fine particles of slurry remain in the interface and cause the first O-ring  155  and the second O-ring  156  to be worn because of the resilient nature of the first O-ring  155  and the second O-ring  156 . Furthermore a constant compressive stress given to the first O-ring  155  and the second O-ring  156  causes a stress relaxation and permanent deformation, which will reduce the intended resilient urging forces. 
   In the first prior art when a pressure accumulated in the ambient passage chamber  126  is applied to the first resilient ring  102  and the second resilient ring  103  where the pressure is received by the respective curved concave surfaces  105 ,  105 , this will cause the curved concave surfaces  105 ,  105  to be further bent toward the internal chamber  127  which in turn will lessen the contact force at the seal surfaces  110 A and  111 A. 
   Promotion of the stress relaxation of the rubber material in the first resilient ring  102  and the second resilient ring  103  will lead to an unwanted permanent deformation in them. At the same time as the respective inner fitting faces  102 B,  103 B of the first resilient ring  102  and the second resilient ring  103 , respectively, undergo elastic deformation in such a manner to depart from the mount groove portions  110 B,  111 B, the seal capability of the inner fitting faces  102 B,  103 B will deteriorate. As a consequence, fine particles contained in the process fluid or sediment located to the side of the ambient passage chamber  126  are trapped between the gaps between the inner fitting faces  102 B,  103 B and the mount groove portions  110 B,  111 B, respectively, which cause an abrasion of the inner fitting faces  102 B,  103 B and a decrease in their seal capability. 
   In the second prior art the first seal ring  152  and the second seal ring  153  are supported by the first O-ring  155  and the second O-ring  156 , respectively. However, the urging force is originated from the resilient reaction force due to a small deformation in the compressed rubber materials of the first O-ring  155  and the second O-ring  156 . Therefore the resilient urging force will quickly decrease as the rubber deformation gets small. For that reason the initial resilient urging force of the first O-ring  155  and the second O-ring  156  needs to be set relatively high by taking a subsequent stress relaxation into consideration. This, however, leads to the acceleration of abrasion of the seal surfaces  152 A and  153 A due to the high urging contact force. 
   Since the first seal ring  152  and the second seal ring  153  are exerted a resiliently urging force by the first O-ring  155  and the second O-ring  156  which are elastically deformed under compressive forces, a progress of the stress relaxation in the first O-ring  155  and the second O-ring  156  decreases their elasticity, as time proceeds, to provide a resiliently urging force to the seal surfaces  152 A and  153 A. Furthermore if slurry is introduced to the joint surface of the first O-ring  155  or the second O-ring  156 , the slurry particles trapped at the joint surface of the first O-ring  155  or the second O-ring  156 , respectively, cause an abrasion of the first O-ring  155  or the second O-ring  156 . 
   The present invention is introduced to alleviate the above mentioned problems. A primary technical goal which this invention tries to achieve is to prevent the abrasion of seal surfaces even under the influence of a process fluid of high pressure or containing slurry. Another goal is to prevent the abrasion of seal surfaces attached with resilient seal rings and to improve the seal capability even when the seal surfaces are subjected to a muddy fluid or the like. Yet another goal is to prevent the stress relaxation of the resilient seal rings in conjunction with elastic deformation and to maintain the seal capability of the resilient seal rings. 
   BRIEF SUMMARY OF THE INVENTION 
   A primary object of the present invention is to alleviate the above mentioned technical disadvantages, and a solution to such disadvantages is embodied as follows. 
   A seal device constructed in accordance with the principles of the present invention is a seal device to provide a seal between one component and the other component which make a rotary motion relative to each other. 
   The seal device retains a first seal ring which has a first seal surface at one end and a first retainer portion on the opposite end of the first seal surface. 
   It also retains a second seal ring which has a second seal surface coming in a seal-tight contact against the first seal surface of the first seal ring and a second retainer portion on the opposite end of the second seal surface. 
   Furthermore the seal device disposes a first resilient seal ring, made of a rubber resilient material, which has a first resilient seal portion urging the first seal surface of the first seal ring against the second seal surface of the second seal ring, a second seal portion being located on one end of the first resilient seal portion and mating with the first retainer portion of the first seal ring, and a first seal portion being located on the other end of the first resilient seal portion and being in a sealing relation with the one component. 
   The seal device also disposes a second resilient seal ring, made of a rubber resilient material, which has a second resilient seal portion urging the second seal surface of the second seal ring against the first seal surface of the first seal ring, a second seal portion being located on one end of the second resilient seal portion and mating with the second retainer portion of the second seal ring, and a first seal portion being located on the other end of the second resilient seal portion and being in a sealing relation with the other component. 
   The first resilient seal ring disposes a first reinforcement ring which retains a first elastic portion providing a reinforcement to the first resilient seal portion, a first support portion providing a support to the first seal portion at one end of the first elastic portion and a second support portion providing a support to the second seal portion at the other end of the first elastic portion. 
   The second resilient seal ring disposes a second reinforcement ring which retains a second elastic portion providing a reinforcement to the second resilient seal portion, a first support portion providing a support to the first seal portion at one end of the second elastic portion and a second support portion providing a support to the second seal portion at the other end of the second elastic portion. 
   In a seal device related to the present invention, since a first seal portion of a first resilient body element and a first seal portion of a second resilient body element are supported by individual first support portions the respective first seal portions effectively maintain stable sealing relations with individual mounting surfaces. Also the individual support portions are capable of providing a secure support to the first resilient seal portion and the second resilient seal portion even when the individual first seal portions are subject to external forces. Therefore the individual first seal portions hardly allow slurry or impurities to go into the interface between the first seal portion and its mating fixing portion, and a decline of the seal capability at the interfaces due to wear of the first seal portions is effectively prevented. A second seal portion of the first resilient body element as well as a second seal portion of the second resilient body element provide a similar effect to the first seal portions do. In particular, the individual second seal portions provide a secure support against the seal rings. And a first elastic portion and second elastic portion give a resilient reinforcement to the first resilient seal portion and the second resilient seal portion, respectively, such that a decrease in the elastic force due to a stress relaxation of the first resilient seal portion and the second resilient seal portion is supplemented. 
   According to the seal device, attaching a first reinforcement ring and a second reinforcement ring in an integral manner to the first resilient seal ring and the second resilient seal ring further effects a secure contact by urging the individual first seal portions against one component and the other component, respectively, by means of the individual first support portions. Also the individual second support portions resiliently urge the individual second seal portions against the first seal ring and the second seal ring, respectively. Therefore even if slurry gets into the interface between the second seal portion and the first seal ring or between the second seal portion and the second seal ring the impurities resiliently held by the interfaces of the second seal portions do not cause wear of the interfaces. In addition resilient forces of the first resilient seal portion and the second resilient seal portion can be adjusted, respectively, by means of the first reinforcement ring and the second reinforcement ring. This enables an accurate design of the resilient forces of the first resilient seal portion and the second resilient seal portion. Furthermore possible stress relaxations in the first resilient body element and the second resilient body element can be compensated, respectively, by the first reinforcement ring and the second reinforcement ring for the lasting exhibition of substantial elastic forces against the first seal ring and the second seal ring. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of a half portion of a seal device illustrating a first embodiment related to the present invention; 
       FIG. 2  is a cross-sectional view of a half portion of a reduction gear unit mounting the seal device of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of a half portion of a first resilient seal ring used for a seal device illustrating a second embodiment related to the present invention; 
       FIG. 4  is a cross-sectional view of a half portion of a first resilient seal ring used for a seal device illustrating a third embodiment related to the present invention; 
       FIG. 5  is a cross-sectional view of a half portion of a first resilient seal ring used for a seal device illustrating a fourth embodiment related to the present invention; 
       FIG. 6  is a cross-sectional view of a half portion of a first resilient seal ring used for a seal device illustrating a fifth embodiment related to the present invention; 
       FIG. 7  is a cross-sectional view of a half portion of a seal device illustrating a sixth embodiment related to the present invention; 
       FIG. 8  is a cross-sectional view of a seal device of a first prior art related to the present invention; and 
       FIG. 9  is a cross-sectional view of a half portion of a seal device of a second prior art related to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Described below is details of the figures of preferred embodiments of the present invention according to actual design drawings with accurate dimensional relations.  FIG. 1  is a cross-sectional view of a half portion of a seal device  1  illustrating a first embodiment related to the present invention.  FIG. 2  is a cross-sectional view of a half portion of a reduction gear unit mounting the seal device  1  of  FIG. 1 . 
   In  FIG. 1  and  FIG. 2 , the seal device  1  is disposed within a seal chamber  70  which is formed between a roller  50  and a shaft  60 . The seal chamber  70  is defined as an inner space surrounded by the shaft  60 , a first fixture surface  51 A of a bushing  51  which is mounted via a O-ring  20  at the end portion of the roller  50 , and a second fixture surface  61 A of a cover  61  which is attached to the shaft  60 . This seal chamber  70  communicates with an ambient communication passage A. 
   The seal device  1  retains a first resilient seal ring  2  and a second resilient seal ring  3 . The first resilient seal ring  2  consists of an annularly shaped first resilient body member  12  made of rubber and a first reinforcement ring  22  made of metal which are joined together to form an integral part. The main body of the first resilient body member  12  defines a slanted first resilient seal portion  12 A. Furthermore the outer perimeter wall of the first resilient seal portion  12 A defines a first seal portion  12 B (it is hereafter called a first outer perimeter seal portion) while the inner perimeter wall defines a second seal portion  12 C (it is hereafter called a second inner perimeter seal portion). The outer surface of the first outer perimeter seal portion  12 B may dispose a plurality of ridges such that the outer surface exhibits a better contact with the first fixture surface  51 A. The second inner perimeter seal portion  12 C fits the outer diameter surface of a cylindrical first retainer portion  4 B of a first seal ring  4 . A bent corner of the second inner perimeter seal portion  12 C, defined as a first joint portion  12 D, make a sealing contact with a first corner portion  4 B 1  of the first seal ring  4 . The contact surface of the second inner perimeter seal portion  12 C may well be prepared with a wavy surface profile in its cross-section for a better contact (not shown in the figure). 
   The first resilient body member  12  of the first resilient seal ring  2  is made of a rubber material such as nitrile rubber (NBR) of hardness DuroA 60 to 70, urethane rubber (U), fluoro rubber (FKM), isobutylene-isoprene rubber(IIR), elastic resin or the like. 
   The first reinforcement ring  22  is adhesively joined with the annularly shaped sidewall of the first resilient body member  12 . The overall shape of the first reinforcement ring  22  is similar to the first resilient body member  12  and the ring  22  is made of a steel plate or a resin which is harder than the first resilient body member  12 . The main body of the first reinforcement ring  22  defines a first elastic portion  22 A which is slanted similarly to the first resilient seal portion  12 A. The outer perimeter surface of the first elastic portion  22 A defines a first support portion  22 B (it is hereafter called a first outer perimeter support portion). The first outer perimeter support portion  22 B comes in an adhesive contact with the inner surface of the first outer perimeter seal portion  12 B, and provides the first outer perimeter seal portion  12 B with an elastic support by forming a close contact between the first outer perimeter seal portion  12 B and the first fixture surface  51 A. 
   The inner perimeter surface of the first elastic portion  22 A defines a second support portion  22 C (it is hereafter called a second inner perimeter support portion). The second inner perimeter support portion  22 C comes in an adhesive contact with the outer surface of the second inner perimeter seal portion  12 C, and provides the first outer perimeter seal portion  12 B with an elastic support by forming a close contact between the second inner perimeter seal portion  12 C and the first seal ring  4 . The first reinforcement ring  22  is made of spring steel, stainless steel, hard resin or the like. Such a material in a sheet form is press-formed to fabricate the first reinforcement ring  22 . 
   The second resilient seal ring  3 , which is disposed in a symmetric manner relative to the first resilient seal ring  2 , has a symmetric shape relative to the first resilient seal ring  2 . The second resilient seal ring  3  consists of a second resilient body member  13  and a second reinforcement ring  23  which are assembled in an integral manner. The second resilient body member  13  retains a second resilient seal portion  13 A which is disposed at an angle. Furthermore the outer perimeter wall of the second resilient seal portion  13 A defines a first seal portion  13 B (it is hereafter called a first outer perimeter seal portion) while the inner perimeter wall defines a second seal portion  13 C (it is hereafter called a second inner perimeter seal portion). The outer surface of the first outer perimeter seal portion  13 B may dispose a plurality of ridges which do not appear in the figure such that the outer surface exhibits a better contact with the second fixture surface  61 A. The second inner perimeter seal portion  13 C fits the outer diameter surface of a cylindrical first retainer portion  4 B of a second seal ring  5 . A bent corner of the second inner perimeter seal portion  13 C, defined as a second joint portion  13 D, make a sealing contact with a second corner portion  5 B 1  of the second seal ring  5 . The contact surface of the second inner perimeter seal portion  13 C may well be prepared with a wavy surface profile in its cross-section for a seal-tight contact which is not shown in the figure. 
   The second resilient body member  13  of the second resilient seal ring  3  is, similarly to the first resilient body member  12 , made of a rubber material such as nitrile rubber (NBR) of hardness DuroA 60 to 70, urethane rubber (U), fluoro rubber (FKM), isobutylene-isoprene rubber (IIR), elastic resin or the like. 
   The second reinforcement ring  23  is adhesively joined with the annularly shaped sidewall of the second resilient body member  13 . The overall shape of the second reinforcement ring  23  is similar to the second resilient body member  13  and the ring  23  is made of a steel plate or a resin which is harder than the second resilient body member  13 . The main body of the second reinforcement ring  23  defines a second elastic portion  23 A which is slanted similarly to the second resilient seal portion  13 A. The outer perimeter surface of the second elastic portion  23 A defines a first support portion  23 B (it is hereafter called a first outer perimeter support portion). In addition a second elastic support portion  23 C (it is hereafter called a second inner perimeter support portion) is disposed at the radially inward end of the second elastic portion  23 A where the second inner perimeter support portion  23 C comes in an adhesive contact with the second inner perimeter seal portion  13 C. The second reinforcement ring  23  is made of spring steel, stainless steel, hard resin or the like. Such a material in a sheet form is press-formed to fabricate the second reinforcement ring  23 . 
   The pair of the first seal ring  4  and the second seal ring  5  are disposed in a symmetrical manner, and the first seal ring  4  and the second seal ring  5  have a symmetrically identical shape with respect to the interface where the first seal surface  4 A and the second seal surface  5 A come in contact with each other. In more details, the first seal ring  4  has an annularly shaped body with an L-shaped cross-section, which consists of a flange portion and a cylinder portion. The end face of the flange portion of the first seal ring  4  defines the first seal surface  4 A. The radially inward portion of the first seal surface  4 A forms a tapered surface such that the first seal surface  4 A does not come in contact with the opposed radially inward portion of the second seal surface  5 A. The cylindrical portion of the first seal ring  4  defines a first retainer portion  4 B. The flange side of the first retainer portion  4 B then defines a first corner portion  4 B 1 , and an inner diameter surface  4 E of the first seal ring  4  defining a bore maintains a clearance relative to the shaft  60 . 
   The mating second seal ring  5  has an annularly shaped body with an L-shaped cross-section, which consists of a flange portion and a cylinder portion. The end face of the flange portion of the second seal ring  5  defines the second seal surface  5 A. The radially inward portion of the second seal surface  5 A forms an axially tapered surface such that the second seal surface  5 A does not come in contact with the opposed radially inward portion of the first seal surface  4 A. The cylindrical portion of the second seal ring  5  defines a second retainer portion  5 B. The flange side of the second retainer portion  5 B then defines a second corner portion  5 B 1 , and an inner diameter surface  5 E of the second seal ring  5  defining a bore maintains a clearance relative to the shaft  60 . 
   The first seal ring  4  and the second seal ring  5  are made of cast iron, SiC, super-hard alloy, alumina ceramics or the like. Or one of the first seal ring  4  and the second seal ring  5  can be made of carbon material. Compression molding is applied to these materials for forming the first seal ring  4  and the second seal ring  5 . 
   In the first resilient seal ring  2  thus constructed, as seen in  FIG. 1  and  FIG. 2 , the first outer perimeter seal portion  12 B fits the first fixture surface  51 A of the bushing  51  while the inner diameter surface of the second inner perimeter seal portion  12 C fits the first retainer portion  4 B of the first seal ring  4 . Under this circumstance, the first joint portion  12 D engages the first corner portion  4 B 1  so as to provide a resilient support for the first seal ring  4 . The first seal surface  4 A of the first seal ring  4  is resiliently urged toward the second seal surface  5 A of the second seal ring  5  by the spring force which is generated by the first resilient seal portion  12 A as well as the first elastic portion  22 A of the first resilient seal ring  2 . Therefore, the first reinforcement ring  22  disposing the first elastic portion  22 A effectively prevents the second inner perimeter seal portion  12 C from being displaced toward the internal chamber B by the pressure coming through the ambient passage A. 
   As for the second resilient seal ring  3 , the first outer perimeter seal portion  13 B, just like in the first resilient seal ring  2 , fits the second fixture surface  61 A while the inner diameter surface of the second inner perimeter seal portion  13 C fits the second retainer portion  5 B of the second seal ring  5 . Under this circumstance, the second joint portion  13 D engages the second corner portion  5 B 1  so as to provide a resilient support for the second seal ring  5 . The second seal surface  5 A of the first seal ring  5  is resiliently urged toward the first seal surface  4 A of the first seal ring  4  by the spring force which is generated by the second resilient seal portion  13 A as well as the second elastic portion  23 A of the second resilient seal ring  3 . Consequently, the second reinforcement ring  23  disposing the second elastic portion  23 A effectively prevents the second inner perimeter seal portion  13 C from being displaced toward the internal chamber B by the pressure coming through the ambient passage A. Therefore, the second resilient seal ring  3  is able to provide the second seal surface  5 A with a sufficient, resilient force for maintaining a seal-tight contact relative to the first seal surface  4 A. In the seal device  1  illustrated in  FIG. 2 , the first seal ring  4  is subjected to a rotary motion as the roller  50  rotates. The second seal ring  5 , on the other hand, remains stationary. Arrangement of the rotating first seal ring  4  and the stationary second seal ring  5  can be swapped depending on the purpose of a machine wherein the seal device  1  is installed. 
   The seal device  1  effects a seal against a gradually increased pressure fluid, muddy water or the like which is allowed to flow in through the ambient passage A as the roller  50  rotates. In an adjacency of the internal chamber B, the roller  50  and the shaft  60  dispose bearings  25  therebetween and lubricants applied thereto. Even if the lubricants exert a pressure to the first resilient seal ring  2  and the second resilient seal ring  3 , the support offered by the first reinforcement ring  22  and the second reinforcement ring  23 , respectively, maintain elastic deformation of the rings without a drop of the seal capability. The resilient forces of the first reinforcement ring  22  and the second reinforcement ring  23  will rather lead to enhancing the seal capability as the result of more secure contact between the two seal surfaces  4 A,  5 A. 
     FIG. 3  shows a half cross-sectional view of a first resilient seal ring  2  as a second preferred embodiment of the present invention. As clearly seen in  FIG. 1 , the second resilient seal ring  3  is made symmetric in relation to the first resilient seal ring  2  in terms of its arrangement and shape. Description of the second resilient seal ring  3  is therefore omitted. The first resilient seal ring  2  (similarly the second resilient seal ring  3 ) of  FIG. 3  differs from that of  FIG. 1  in the sense that the end portion of the first outer perimeter support portion  22 B of the first reinforcement ring  22  is bent radially inward, which is defined as a first reinforcement portion  22 B 1 , and also that the second inner perimeter support portion  22 C is bent radially outward, which is defined as a second reinforcement portion  22 C 1 . 
   The first reinforcement ring  22  thus arranged results in the improved strength of the first outer perimeter support portion  22 B and the second inner perimeter support portion  22 C after being mounted therein. Also arranging a plurality of ridge-shaped seal portions, not shown in the figure, on the perimeter surfaces of the first outer perimeter seal portion  12 B and the second inner perimeter seal portion  12 C not only is capable of the resilient fit thereof but also is able to improve the seal performance thereof. Parts indicated by other numerals in  FIG. 3  can be considered to be more or less the same in their forms and dimensions as those at the same numerals of  FIG. 1 . 
     FIG. 4  shows a half cross-sectional view of a first resilient seal ring  2  as a third preferred embodiment of the present invention. A first resilient seal ring  2  of  FIG. 4  is obtained by bending a second inner perimeter support portion  22 C of the first resilient seal ring  2  shown in  FIG. 1  to form a circular arc which is defined as a third support portion  22 D (bending support portion). Embedding, in this way, the third support portion  22 D of the first reinforcement ring  22  in a second inner perimeter seal portion  12 C makes the third support portion  22 D be integrated with the second inner perimeter seal portion  12 C and enables the third support portion  22 D to effect a secure, seal fit in relation to a first seal ring  4  via the second inner perimeter seal portion  12 C. As the result, the seal performance of the second inner perimeter seal portion  12 C against the first seal ring  4  will improve. In addition a sufficient, resilient support of the first elastic portion  22 A is provided for accommodating to excursions of the first seal ring  4  in use. Parts indicated by other numerals in  FIG. 4  can be considered to be more or less the same in their forms and dimensions as those at the same numerals of  FIG. 1 . 
     FIG. 5  shows a half cross-sectional view of a first resilient seal ring  2  as a fourth preferred embodiment of the present invention. The first resilient seal ring  2  of  FIG. 5  differs from that of  FIG. 3  in that a plurality of slit portions  26  are disposed along the circumference of a first elastic portion  22 A of a first reinforcement ring  22  wherein the slit portions  26  are located essentially in a equally spaced manner. This makes it possible that when the first resilient body member  12  is molded with a rubber material, a portion of a first resilient seal portion  12 A gets inside the slit portions  26  of the first reinforcement ring  22  to form an integral structure therewith (note that every resilient seal portion  12 A,  13 A does not need to be integral with its mating slit portion  26  to obtain a similar effect). Disposing the slit portions  26  in this way in the first reinforcement ring  22  of the first resilient seal ring  2  effects an optimal design for the resilient strength by means of adjusting the leaf spring means between adjacent slit portions  26  as well as for the degree of contact between the first reinforcement ring  22  and the first resilient body member  12 . 
   That is, adjusting the strip width between adjacent slit portions  26  of the first elastic portion  22 A allows one to choose a desirable, resiliently urging force against a first seal ring  4 . Therefore, the resiliently, urging, contact force thus provided at a first seal surface  4 A effectively leads to avoiding wear of the first seal surface  4 A and a second seal surface  5 A as well as excessive contact forces at these seal surfaces. The slit portion  26  has a narrow width extending along the circumference wherein the slit is manufactured by a machine tool such as slotting or end-mill. The slit portion  26  whose width is relatively wide may be defined as a notch portion. Such a notch portion may be fabricated as a rectangular window radially extending in the first elastic portion  22 A and the second elastic portion  23 A. The slit portion  26  (or notch portion) can be further extended to a portion of a first support portion  22 B and/or a second support portion  22 C of the first reinforcement ring  22 . The dimension of the notch portion can be arbitrarily determined according to considerations taken on the slit portion  26  of  FIG. 5 . Parts indicated by other numerals in  FIG. 5  can be considered to be more or less the same in their forms and dimensions as those at the same numerals of  FIG. 1 . 
     FIG. 6  shows a half cross-sectional view of a first resilient seal ring  2  as a fifth preferred embodiment of the present invention. The first resilient seal ring  2  of  FIG. 6  disposes a protruded mating portion  15  on one of the annular side surfaces of a first resilient body member  12 . The first reinforcement ring  22  also disposes, at a location corresponding to the mating portion  15 , a mount bore  25  which is a through hole. Inserting the mating portion  15  into the mount bore  25  makes an integral construction of the first resilient body member  12  and the first reinforcement ring  22 . The first resilient body member  12  thus arranged is able to improve elastic support capability against a first seal ring  4  of a first elastic portion  22 A by means of the mount bore  25  disposed in the first reinforcement ring  22 . In addition the first resilient body member  12  and the first reinforcement ring  22  can be manufactured individually and be assembled when needed. Since the mount bore  25  of the first reinforcement ring  22  is capable of mating with the mating portion  15 , detachment of the first reinforcement ring  22  from the first resilient body member  12  can effectively be prevented even if the contact strength between the two components decreases due to a rubber material used in the first resilient body member  12 . Parts indicated by other numerals in  FIG. 6  can be considered to be more or less the same in their forms and dimensions as those at the same numerals of  FIG. 1 . 
     FIG. 7  shows a half cross-sectional view of a seal  1  as a sixth preferred embodiment of the present invention. The seal  1  of  FIG. 7  differs from that of  FIG. 1  in that the first reinforcement ring  22  and the second reinforcement ring  23 , respectively, are embedded within the first resilient body member  12  adjacent the first opposing surface  2 P 1  (ambient passage A side) and the second resilient body member  13  adjacent the second opposing surface  3 P 1  (ambient passage A side). The first reinforcement ring  22  and the second reinforcement ring  23  are preferably located toward the first opposing surface  2 P 1  relative to the neutral line N of the first resilient body member  12  and toward the second opposing surface  3 P 1  relative to the neutral line N of the second resilient body member  13 , respectively. The individual neutral lines N are defined at a distance X 1  from the opposing surface  2 P 1  of the first resilient body member  12  and also X 1  from the opposing surface  3 P 1  of the second resilient body member  13 , respectively, and X 2  from a first back surface  2 P 2  and a second back surface  3 P 2 , respectively. 
   Comparing with the first resilient body member  12  and the second resilient body member  13  in  FIG. 1 , thickness of the first resilient body member  12  and the second resilient body member  13  in  FIG. 7  is increased to X 1 +X 2 . In this way, the first reinforcement ring  22  and the second reinforcement ring  23  of  FIG. 7  can be made thinner than the first reinforcement ring  22  and the second reinforcement ring  23  of  FIG. 1 , and the end portions of the first outer perimeter support portion  22 B of the first reinforcement ring  22  and the second outer perimeter support portion  23 B of the second reinforcement ring  23  are both bent radially inward, which are defined as a first reinforcement portion  22 B 1  and a second reinforcement portion  23 B 1 , respectively. Also the second inner support portion  22 C and the second inner support portion  23 C of  FIG. 1  are circularly bent, respectively, to form a fourth support portion (elastic support portion)  22 E and a fourth support portion (elastic support portion)  23 E. 
   The first resilient seal ring  2  is disposed between the first seal ring  4  and the bushing  51  while the second resilient seal ring  3  is between the second seal ring  5  and the cover  61 . For an improvement of the seal capability, the first opposing surface  2 P 1  and the second opposing surface  3 P 1  and, respectively, the first back surface  2 P 2  and the second back surface  3 P 2  preferably undergo elastic deformation, as shown in  FIG. 7 , such that they form a convex shape toward the ambient passage side A. Such elastic deformation as shown in  FIG. 7  of the first resilient seal ring  2  and the second resilient seal ring  3  enables the first resilient seal ring  2  and the second resilient seal ring  3  to sustain high pressure of the fluid incoming from the ambient passage A, owing to the reaction forces provided by the first reinforcement ring  22  and the second reinforcement ring  23 . The first reinforcement ring  22  also prevents the second inner perimeter seal portion  12 C from coming off the first seal ring  4  toward the internal chamber B. Similarly the second reinforcement ring  23  prevents the second inner perimeter seal portion  13 C from coming off the second seal ring  5  in the outward direction. Therefore an improvement of the contact between the second inner perimeter seal portion  12 C and the first seal ring  4  is achieved. So is the contact between the second inner perimeter seal portion  13 C and the second seal ring  5 . 
   The first resilient seal ring  2  which appears in  FIG. 3  through  FIG. 7  is made of a rubber material such as nitrile rubber, silicone rubber, fluoro-rubber, acrylic rubber, styrene rubber, ethylene propylene rubber, urethane rubber or the like. Although  FIG. 3  through  FIG. 6  show the first resilient seal ring  2  alone, the second resilient seal ring  3  is merely arranged in a symmetric manner relative to the first resilient seal ring  2  and a shape and material used is more or less the same as the first resilient seal ring  2 . 
   The first resilient body member  12  of the first resilient seal ring  2  and the second resilient body member  13  of the second resilient seal ring  3  are reinforced with respect to elasticity by means of the first reinforcement ring  22  and the second reinforcement ring  23 , respectively. Therefore a soft rubber or resin can be used as a material for the second resilient body member  13  as well as for the first resilient body member  12 . In this way, the first outer perimeter seal portion  12 B, the first outer perimeter seal portion  13 B, the second inner perimeter seal portion  12 C, and the second inner perimeter seal portion  13 C, can improve the seal capability at the respective seal surfaces with their corresponding mating portions, i.e., the first fixture surface  51 A, the second fixture surface  52 A, the first retainer portion  4 B and the second retainer portion  5 B. 
   Furthermore the use of a soft rubber material for the inner and outer seal portions  12 B,  12 C,  13 B,  13 C effectively prevents wear of the inner and outer seal portions  12 B,  12 C,  13 B,  13 C even if slurry deposits on the contact surfaces of the inner and outer seal portions  12 B,  12 C,  13 B,  13 C. Also the first resilient seal ring  2  of  FIG. 1  can be substituted by first resilient seal ring  2  of  FIG. 7 . Likewise the second resilient seal ring  3  of  FIG. 1  can be substituted by the second resilient seal ring  3  of  FIG. 3 . This implies that different forms of the first resilient seal ring  2  and the second resilient seal ring  3  can be combined according to the operational conditions of the fluid and pressure of the internal chamber B. This kind of combination allows the first seal surface  4 A and the second seal surface  5 A to effectively come in sealing contact even under the above mentioned difficult situations. Thus a seal capability of the first and second seal surfaces  4 A,  5 A improves. 
   Described next is an alternative embodiment related to the present invention. 
   In a seal device  1  as a second preferred embodiment related to the present invention, at least one of a first elastic portion  22 A of a first reinforcement ring  22  and a second elastic portion  23 A of a second reinforcement ring  23  retains a plurality of notch portions  26  or slit portions  26  along the perimeter surface. 
   Since the seal device  1  related to the second embodiment disposes the first reinforcement ring  22  and/or the second reinforcement ring  23  with notch portions  26  or slit portions  26  therein, the individual elastic portions  22 A,  23 A between the adjacent notches  26  or slits  26  can be considered as leaf springs, so that the resilient forces exerted by the elastic portions  22 A,  23 A can be arbitrarily designed (or spring forces of the elastic portions  22 A,  23 A can be adjusted according to design specifications). At the same time, introducing a portion of the material of the resilient seal portions  12 A,  13 A into the notch portions  26  or the slit portions  26  in the manufacturing process of the resilient seal portions  12 A,  13 A, provides an improvement on the integral force between the individual resilient seal portions  12 A,  13 A and corresponding reinforcement rings  22 ,  23 , respectively. The notch portion  26  or slit portion  26  may be fabricated like a rectangular window in the elastic portions  22 A,  23 A. Also as an alternative way of forming the first elastic portions  22 A and the second elastic portions  23 A, the notch portion  26  or slit portion  26  may be disposed in either one of the first support portion  22 B or the second support portion  23 B 
   Furthermore a seal device  1  as the second embodiment related to the present invention provides the following advantages. Disposition of slit portions  26  or notch portions  26  in a first reinforcement ring  22  and a second reinforcement ring  23  enables an optimal design of elastic forces generated by the first reinforcement ring  22  and the second reinforcement ring  23 . This in turn provides an optimal, resiliently urging, support at the seal surfaces  4 A,  5 A of a first seal ring  4  and a second seal ring  5 , respectively. In addition the integration of a first resilient body member  12  and a second resilient body member  13 , respectively, with the first reinforcement ring  22  and the second reinforcement ring  23  by means of the slit portions  26  or the notch portions  26 , not only enhances the bonding strength of the first reinforcement ring  22  and the second reinforcement ring  23  but also is capable of providing a substantial resilient support even for a non-adhesive material in use for the both components. 
   A seal device  1  as a third embodiment related to the present invention disposes a first reinforcement ring  22  of a first resilient seal ring  2  at the opposite side of the first resilient seal ring  2  with respect to a process fluid and a second reinforcement ring  23  of a second resilient seal ring  3  at the opposite side of the second resilient seal ring  3  with respect to the fluid. 
   In the seal device  1  as a third embodiment related to the present invention, since the first reinforcement ring  22  and the second reinforcement ring  23  are mounted onto the first resilient seal ring  2  and the second resilient seal ring  3 , respectively, at the opposite side relative to the process fluid, it is less likely for inclusions in the fluid to go into between the mating surfaces at the individual contact surfaces, i.e., first seal portions  12 B,  13 B and second seal portions  12 C,  13 C, and this prevents the inclusions from causing abrasion of the mating contact surfaces and the individual seal portions  12 B,  13 B,  12 C,  13 C. Wear of the seal portions  12 B,  13 B,  12 C,  13 C is thus avoided and their seal capability can be exhibited in a satisfactory manner. Also the absence of contact with the fluid effectively prevents the reinforcement rings  22 ,  23  from capturing rust. Furthermore the individual reinforcement rings  22 ,  23  are not only capable of providing the resilient seals  12 A,  13 A with a reinforcement support from the opposite side of the resilient seal rings  2 ,  3  relative to the fluid, respectively, and but also capable of producing resiliently, urging forces against the individual seal rings  4 ,  5  in a long term. 
   In addition a seal device  1  as the third embodiment related to the present invention provides the following advantages. Disposing the first reinforcement ring  22  and the second reinforcement ring  23  within the side wall of the annularly-shaped body of the first resilient body member  12  and the second resilient body member  13 , respectively, provides a seal-tight contact at the first seal portions  12 B,  13 B against the first fixing portion  51 A and the second fixing portion  61 A, respectively, as well as at the second seal portions  12 C,  13 C against the first seal ring  4  and the second seal ring  5 , respectively. Hence the contact forces at the individual contacting surfaces are enhanced. Furthermore even when slurry particles get into at the interface between the first seal portions  12 B,  13 B and the mating first fixing portion  51 A and the second fixing portion  61 A, respectively, and/or at the interface between the second seal portions  12 C,  13 C and the mating first seal ring  4  and the second seal ring  5 , respectively, rubber materials used for the first seal portions  12 B,  13 B and the second seal portions  12 C,  13 C effectively prevents the slurry particles from causing wear. 
   In a seal device  1  as a fourth embodiment related to the present invention, individual second support portions  22 C,  23 C have a shape of circular-arc or are bent at several points to form a piecewise straight contour and also are embedded in the second seal portions  12 C,  13 C, respectively. 
   In the seal device  1  of the fourth embodiment related to the present invention, second support portions  22 C,  23 C not only are bent in a circular shape or at multiple inflection points but also are embedded inside second seal portions  12 C,  13 C. The second seal portions  12 C,  13 C embedding the bent, strong second support portions  22 C,  23 C therewithin can provide a support such that the seal surfaces  4 A,  5 A come in a seal-tight contact. This effectively prevents slurry particles from entering the interface formed between the contact surfaces of the second seal portions  12 C,  13 C and their opposed, mating contact surfaces. It also prevents wear due to slurry particles being present at the interface. 
   Furthermore the rubber elastic force in the second seal portions  12 C,  13 C enables a seal-tight contact of the second seal portions  12 C,  13 C against the second retainer portions  4 B,  5 B. The seal capability at the interface between the second seal portions  12 C,  13 C and the second retainer portions  4 B,  5 B, respectively, is thus improved. Also the second seal portions  12 C,  13 C are securely fit with the second retainer portions  4 B,  5 B, respectively, by using a small contact width. It can therefore be used to support seal rings  4 ,  5  of a small size. 
   In a seal device  1  as a fifth embodiment related to the present invention, a first reinforcement ring  22  and a second reinforcement ring  23  are disposed toward the fluid side relative to the neutral line along the thickness direction of a first resilient seal ring  2  and relative to the neutral line along the thickness direction of a second resilient seal ring  3 , respectively 
   The seal device  1  of the fourth embodiment related to the present invention is particularly effective when the individual seal rings  2 ,  3  are made large in thickness. It is also effective when first seal portions  12 B,  13 B and second seal portions  12 C,  13 C are made in a large size. It is most suitable for such a case that resilient forces of resilient seal portions  12 A,  13 A and resilient forces of elastic portions  22 A,  23 A are to be carefully designed. In the seal device  1  thus arranged, the individual reinforcement ring  22 ,  23  can be made slim relative to the resilient seal portions  12 A,  13 A. Embedding the reinforcement rings  22 ,  23  toward the fluid side of the resilient seal portions  12 A,  13 A not only promotes the elastic deformation on the installation but also prevents slurry from going into the joint surfaces of the individual seal portions  12 B,  13 B,  12 C,  13 C by means of the coordination of the reinforcement rings  22 ,  23  embedded in the fluid side and the rubber resilient material of a large thickness located toward the fluid side relative to the reinforcement rings  22 ,  23 . 
   Furthermore in the seal device  1  of the fourth embodiment related to the present invention, the individual third support portions  23 D of the first reinforcement ring  22  and the second reinforcement ring  23  which are bent in a circularly arc shape or at multiple inflection points not only improve the contact forces against the second seal portions  12 C,  13 C but also provide a resiliently, urging force in order to urge the seal surfaces  4 A,  5 A of the first seal ring  4  and the second seal ring  5 , respectively, to a seal-tight contact. In addition embedding the first reinforcement ring  22  and the second reinforcement ring  23  toward the oppositely facing direction of the first resilient body member  12  and the second resilient body member  13 , respectively, as well as making the resilient body members  12 ,  13  thick enables the first elastic portion  22 A and the second elastic portion  23 A to exhibit a resilient support. Also softening the rubber elastic force of the first elastic portion  22 A and the second elastic portion  23 A effectively prevents the joint surfaces of the first seal portions  12 B,  13 B and the second seal portions  12 C,  13 C from being worn by the slurry remaining in the joint surfaces, and accordingly improves the seal capability of the individual joint surfaces of the first seal portions  12 B,  13 B and the second seal portions  12 C,  13 C. 
   Having described specific embodiments of the invention, however, the descriptions of these embodiments do not cover the whole scope of the present invention nor do they limit the invention to the aspects disclosed herein, and therefore it is apparent that various changes or modifications may be made from these embodiments. The technical scope of the invention is specified by the claims.