Abstract:
A male coupling portion of a first split portion on one side of a split boot is coupled to a female coupling portion of a second split portion using a plurality of spaced male and female coupling portions. A worker can simply couple the split portions of split boot without using any machine while enhancing the coupling force of split faces.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a boot to be assembled in split for sealing the slide portion of flexible coupling mounted to a shaft. This invention relates in particular to the boot which can be opened from its lateral side for its fitting with the shaft being interconnected to the flexible coupling. 
     2. Description of the Related Art 
     The boot shown in FIG.  26  and FIG. 27 exists to the prior art relating to this invention. 
     FIG. 26 is an oblique view of the boot with its split face being opened. FIG. 27 is a cross sectional view with its split face being coupled. 
     The bellows status split boot  51  in FIG. 26 is split in the axial direction at one place, and the split face on one hand is not only formed on an insertion piece  52  and the split face on the other hand is formed to an annular concave  55  so that these split faces may be coupled mutually to each other. 
     FIG. 27 indicates the status where the insertion piece  52  is press-fitted for its coupling into this annular concave  55 . 
     In FIG. 27, the insertion piece  52  having the split face on one hand is formed into a sickle state from the split face and has an engaging stage portion  53  swollen out to both the sides. And, it is formed to a slope face  54  being throttled toward the tip from both the sides of engaging stage portion  53 . This insertion piece  52  is formed over the entire length in the axial direction along the bellows status split face. 
     Next, the annular concave portion  55  is formed to the split face on the other hand so that the insertion piece  52  can be inserted. This annular concave portion  55  opens with the protrusion piece  56  being provided on both the sides of split, and its interior is formed to the space of triangle shape in its cross section so that the tip side of insertion piece  52  can be engaged having an interval. 
     And, when the insertion piece  52  is press-fitted into the annular concave portion  55 , it can be fitted as shown in FIG. 27 with the engaging stage portion being engaged to the protrusion piece and both the split faces tend to maintain the coupled status. 
     SUMMARY OF THE INVENTION 
     Because the above mentioned boot is formed into a bellows shape and is but also structured flexibly, it includes a significant amount of rubber material. Therefore, because the friction of rubber material is great when inserting and coupling the insertion piece  52  into the annular concave portion  55 , the insertion process is difficult. Moreover, because the boot is crooked in order to from a bellows, the insertion process becomes further difficult and the work efficiency decreases. 
     Further, for improving the above mentioned prior art, there exists another prior art where the reinforcing materials are buried inside the annular concave portion and inside the insertion piece of FIG.  13 . The reinforcing material is made of a wire which is bent to a bellows status into the formation of flat face, and this plate shape material is formed into a concave status and buried into the outside circumference side in the space of annular concave portion. Further, the reinforcing material of insertion piece is made of wire that is bent into a bellows status into the formation of plate status and is buried in such that it may be laid toward the tip direction with the insertion piece at its center. 
     However, even in this split boot, the wire can not be thickened because the flexibility of boot entirety aggravates, and it is difficult to solve the above mentioned defects. Moreover, if a strong force acts on the boot  51 , the split faces open resulting in the outflow of lubricating oil. 
     The present invention has been conceived in consideration of the above mentioned problematic points, and its object resides in not only facilitating the coupling of split faces but also strengthening the coupling force between the split faces. 
     Another object of this invention resides in strengthening the joint force of split faces and enhancing the sealing force of split faces. A further object resides in enabling the split coupling even if a diversity of materials such as rubber material, resin material, etc. should be adopted to the material of the boot. 
     The present invention has been conceived for solving the above mentioned themes, and its technical means is structured as follows. 
     A boot according to the present invention includes a mounting portion on both of the end sides of an annular body. The boot is formed attachable to the shaft coupling and is split in an axial direction having a first split portion on a split face side and a second split portion on the split face side. The first split portion has a fixed portion fixed inside the first split portion and an insertion portion protruding from the fixed portion and a male coupling portion having an engaging portion protrusive to the insertion portion. The second split portion has an acceptance portion into which the insertion portion is to be inserted and a female coupling portion having an engaging female portion which closely mates the split face of the first split portion and the split face of the second split portion mutually to the acceptance portion for engagement to the engaging portion. 
     The engaging portion only protrude out of the lateral face of insertion portion, and at least one of the acceptance and the engaging portion is elastically deformed by the mutual pressure. 
     The empty chamber of the acceptance portion may be formed to a larger size against the insertion portion for its idle fitting. 
     The boot may be made of rubber state elastic material, and the coupling portion may be made of a harder material than the rubber state elastic material and the engaging portion may be formed on a top shape outside face tapering to its tip, and a female coupling portion may be made of a harder material than the rubber state elastic material and may also be formed to a female hole mating with the engaging portion for its engagement. 
     The acceptance portion may be formed to an oval hole in the direction along the second split portion and the insertion portion mating to the acceptance portion may be formed to the long width corresponding to the oval hole of acceptance portion and have a concave portion formed toward the fixed portion from the tip face. 
     The fixed portion of male coupling portion may be integrally interconnected by an interconnection plate having a flexibility along the first split portion respectively and the female coupling portion may be integrally interconnected by an interconnection plate having a flexibility along the second split portion respectively. 
     The boot may be a male coinciding portion formed to a convex portion on one side of the first split portion and the second split portion and a female coinciding portion formed to a concave portion so that the other portion may mate to the male coinciding portion. The boot may have an engaging groove at the root of male coinciding portion and a hook portion coupling with the coinciding groove to the end portion of concave portion of female coinciding portion. 
     In the boot according to the present invention, when the engaging portions  8  and  108  a the first split portion should be elastically inserted into and coupled with the coinciding female portions  13  and  113  of acceptance portion of the second split portion, the respective split faces of the first split portion and second split portion get in close contact with each other to prevent the outflow or inflow of fluid into or out of the boot. At the same time, since the insertion portion and acceptance portion are coupled and engaged in one touch, the coupling of mutual split portions becomes facilitated. Because especially it is just all right to couple the male coupling portion with the female coupling portion even if the elasticity deformation should be large like the boot which is made of rubber material, the coupling can be made with no regard to the coupling handling due to the material of boot. 
     The acceptance portion may elastically open the space or the engaging portion may be pressed against the acceptance portion for its elastic deformation, or both of the parts may be elastically deformed so that both the parts may be inserted together and both of the parts are coupled when the acceptance portion  12  and the engaging portion  8  of insertion portion are mutually inserted into each other. For this reason, when both of the members should be restored from the elastic deformation, the coinciding male portion and the engaging portion can be engaged with each other so as to press fit the split faces of both the split portions. In this way, the male coupling portion  4  and the female coupling portion  5  provided along the axial direction of split faces are sequentially coupled with each other. As a result, the boot  1  can be inserted from the lateral side of flexible coupling. 
     Because the empty chamber  12   c  of acceptance portion may be formed to a larger size than the shape of insertion portion  6 , it can be strongly contacted with the split faces of both the split portions because the engaging portion  8  alone can be strongly engaged with the coinciding female portion  13  in the idle status even if the dimension accuracy of both the parties should be more or less incorrect in the engagement. 
     If the respective top status outer faces  110  of engaging portion  108  of the male coupling portion  104  should be sequentially engaged to the engaging coinciding portions  113  of the female coupling portion  105 , they can be easily coupled with each other because each top status outer face  110  is strongly coupled with each coinciding female portion  113 . And it becomes possible to close the flexible coupling by getting the male coupling portion  104  closely contacted with the female coupling portion  105 . And by making the male coupling portion  104  and the female coupling portion  105  from the resin material, both the parts can be press-fitted for their coupling to each other. 
     The insertion portion  106  and the acceptance portion  112  may be formed into a long shape in the longitudinal direction of split and a concave portion may be provided to the insertion portion for its structure of elasticity deformation during its insertion. Thus, both of the split portions can be strongly coupled with each other and the coupling work of both of the split portions can be made without difficulty. 
     Because the male coupling portion  104  and female coupling portion  105  may be integrally interconnected by use of the interconnection plate  117 , both of the parts can be correctly aligned with each other when coupling the male coupling portion with the female coupling portion. Further, the coupling force between the male coupling portion and the first split portion and the coupling force between the female coupling portion and the second split portion become strong. 
     In the boot of this invention, because the coinciding portion  118  may be formed to the first split portion  102  and the female coinciding portion  119  may be formed to the second split portion  103 , the coupled split face will not open and therefore can be securely contacted even if the boot should be subjected to the action of large deformation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a lateral face view before coupling the boot in the mode of one embodiment according to this invention. 
     FIG. 2 is a lateral face view on the larger diameter side mounted portion side of first split face of FIG.  1 . 
     FIG. 3 is a lateral face view of large diameter side mounted portion side of second split face of FIG.  1 . 
     FIG. 4 is a cross sectional view showing the male coupling portion and the female coupling portion owned to the split portion shown in FIG.  1 . 
     FIG. 5 is a cross sectional view having coupled the respective coupling portions of FIG.  4 . 
     FIG. 6 is a lateral face view having mounted the boot of FIG. 1 to the shaft coupling. 
     FIG. 7 is a cross sectional view of having coupled the first split portion and the second split portion, at each coupling portion, of boot in the mode of another embodiment relating to this invention. 
     FIG. 8 is a cross sectional view showing each coupling portion owned to the first split portion and the second split portion in the mode of still another embodiment relating to this invention. 
     FIG. 9 is a cross sectional view showing the respective coupling portions owned to the first split portion and the second split portion of boot in the mode of still another embodiment relating to the present invention. 
     FIG. 10 is a plane view of split part on one hand of female coupling portion of FIG.  9 . 
     FIG. 11 is a lateral side view from the insertion side of split part on one hand of FIG.  10 . 
     FIG. 12 is a lateral side view of boot relating to the mode of first embodiment of this invention. 
     FIG. 13 is an oblique view of male coupling portion shown in FIG.  1 . 
     FIG. 14 is a plane view of engaging portion shown in FIG.  2 . 
     FIG. 15 is a lateral side view of engaging portion shown in FIG.  3 . 
     FIG. 16 is an oblique view of engaging portion shown in FIG.  1 . 
     FIG. 17 is a plane view of coinciding female portion shown in FIG.  5 . 
     FIG. 18 is a lateral side view of coinciding female portion shown in FIG.  6 . 
     FIG. 19 is a cross sectional view in the coupled status of both the coupling portions of boot shown in FIG.  1 . 
     FIG. 20 is a plane view of the boot according to this invention, which is assembled to the flexible coupling. 
     FIG. 21 is a partial plane view of first split face of boot relating to the mode of 2nd embodiment of this invention. 
     FIG. 22 is a partial plane view of second split face joining to the first split face shown in FIG. 10 of this invention. 
     FIG. 23 is a cross sectional view in the coupled status between the engaging portion and coinciding female portion of this invention. 
     FIG. 24 is a cross sectional view in the coupled status between the engaging portion and the coinciding female portion in the mode of another embodiment of this invention. 
     FIG. 25 is a lateral side view of split face side of boot in the mode of another embodiment of this invention. 
     FIG. 26 is an oblique view of conventional split boot. 
     FIG. 27 is a cross sectional view having coupled the split portions of FIG.  26 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereunder, the boot in the mode of embodiment according to this invention is to be expounded with reference to the drawings. 
     FIG. 1 is a lateral side view showing the boot in the mode of first embodiment of the present invention. 
     Numeral  1  in FIG. 1 stands for a boot. A large diameter side mounting portion  20  coupling to the flexible coupling at both the end sides and a small diameter side mounting portion  21  coupling to the shaft are formed on the boot  1 . And a bellows portion  22  is formed in the middle of both mounting portions  20  and  21 . The boot  1  made of rubber material is split at one place in the axial direction, and a first split face  2   a  is not only formed to the first split portion  2  but a second split face  3   a  is also formed to a second split portion  3 . 
     FIG. 2 is a major portion lateral face view looking at the first split portion  2  of FIG. 1 from the side of second split portion  3 . 
     To the first split portion  2 , a plurality of male coupling portions  4  are arranged along the axial direction. This arrangement is one of the embodiments, and the coupling portions are laid out in a great number according to the size of boot. Further, if the male coupling portion  4  and the female coupling portion  5  are also installed to the crest portion  10  and the valley portion  11 , the shapes of male coupling portion  4  and female coupling portion  5  are also formed to the crest shape and the valley shape when viewed from the front face of the respective split portions  2  and  3 . 
     Further, to the second split portion  3 , the female coupling portion  5  is arranged along the axial direction at the position corresponding to the male coupling portion  4  of first split face  2   a  as shown in FIG.  3 . 
     FIG. 4 is a cross sectional view showing the engaging portion  8  and the coinciding portion  13  taken along the line A—A of FIG.  1 . Out of them, the mounting structure of male coupling portion  4  is formed like the right side of FIG.  4 . The male coupling portion  4  is made of metal plate having a flexibility, which is shaped to a rectangularity when viewed from the plane face, and the engaging portion  8  forming a cantilever beam shape whose three sides are cut and inclined is formed to the insertion portion  6 . The inclination angle of this engaging portion  8  is shaped to 20°. Further, the inclination angle α should preferably be set to the range from 5 to 30°. Further, the size of distance “A” from the first split face  2   a  to the tip portion  8   a  of engaging portion  8  needs to be smaller than the size of distance “B” from the contact portion  13   a  of female coupling portion  5  to the second split face  3   a . In addition, the engaging portion may also be structured in a way to have an elasticity by the heat treatment. 
     An integral portion  7  by the through hole is provided to the fixed portion  9  coupling with the first split portion  2  of male coupling portion  4 , and the first split portion  2  penetrates though the integral portion  7  for its coupling integrally. This integral portion  7  may also be structured by coupling the pin to the fixed portion  9  in place of the hole. 
     The female coupling portion  5  interconnecting with the male coupling portion  4  is as shown on the left side of FIG. 4, and is adhered via the bonding agent  14  like a rubber paste to the second split portion  3 . 
     This female coupling portion  5  not simply bends a metallic plate to a U-shape, but both the ends are further bent to a flange shape, and its interior forms an acceptance portion  12  into which the male coupling portion  4  can be inserted easily. The acceptance portion  12  of U-letter shape is structured to elasticity like a leaf spring. This female coupling portion  5  is structured to have an elasticity by spring steel, etc. or by hardening. 
     The coinciding female portion  13  of V-shape space coinciding with the engaging portion  8  is formed to the acceptance portion  12  into which the insertion portion  6  of this male coupling portion  4  is to be inserted. This coinciding portion  13  is formed to the shape approximate with the engaging portion  8 , and is formed to a concave accepting the engaging portion  8 . 
     The female coupling portion  5  is inserted in such a way that if the insertion portion  6  of male coupling portion should be press-fitted, the engaging portion  8  is not only pressure fitted but the acceptance portion  12  of U-shape may be opened slightly elastically. And when the engaging portion  8  should reach the stipulated position, it restores to its original shape by the elasticity and gets coincided with the coinciding female portion  13 . At this time, the “A” size of male coupling portion  4  shown in FIG. 4 is made smaller than the “B” size of female coupling portion  5  so that both the split faces  2   a  and  3   a  may be pressure fitted. This dimensional difference should preferably be set to the size from 0.5 to 1.0 mm. 
     FIG. 5 is a status view which has coupled FIG.  4 . In FIG. 5, the tip portion  8   a  of engaging portion  8  of male coupling portion  4  is pressed against and engaged with the contact portion  13   a  of coinciding female portion  13  of female coupling portion  5 . Unless this engaging portion  8  should be pressed and deformed so that it may be the identical plane state with the insertion portion  6 , the first split portion  2  can not be separated from the second split portion  3 . 
     FIG. 6 is a lateral face view where the male coupling portion  4  and female coupling portion  5  of boot  1  shown in FIG. 1 are coupled together and mounted to the shaft coupling. Further, it shall be so considered that the shaft coupling is structured of the flexible coupling  30  and shaft  31 . 
     In FIG. 6, the flexible coupling  30  is interconnected in free angle with the shaft  31  via the bearing owned inside. And, the lubricating oil is intervened for protecting the sliding face on the side of this bearing. 
     For preventing the outflow of lubricating oil on the side of this bearing and the invasion of dust, etc., the boot  1  shall be fitted to the shaft coupling. As mentioned earlier, the space between the split faces  2   a  and  3   a  of boot  1  shall be opened from the lateral side of shaft coupling for its insertion, and the male coupling portion  4  and female coupling portion  5  shall be mutually coupled to each other into the status as shown in FIG.  6 . And, not only the large diameter side mounting portion  20  shall be tightened via the first band  32  to the outside ring of flexible coupling  30  but the small diameter side mounting portion  21  shall also be tightened to the shaft  31  with the second band  33 . 
     As a result, it becomes possible to eliminate such difficult needs as disassembling the flexible coupling from the unit, inserting the boot into this flexible coupling from the axial direction for its fitting, and assembling the flexible coupling  30  again to the drive unit of shaft  31  as conventionally required. 
     FIG. 7 is a cross sectional view of coupling portion of boot showing the mode of second embodiment according to this invention. 
     In FIG. 7, a through-hole  15  is provided to the female coupling portion  5  and the elastic support portion  16  of the second split portion  3  is passed through this through-hole  15  during the formation and formed integrally in up/down sides. The elastic support portion  16  passing though this through-hole  15  is structured at the position in contact with the end face  17  of insertion portion  6 . 
     And, by this elastic support portion  16 , the tip face of male coupling portion  4  is not only supported, but the female coupling portion  5  is also coupled strongly to the second split portion  3 . 
     Also, one piece of coinciding female portion  13  is installed on one side to the female coupling portion  5 . 
     The female coupling portion  5  is structured of a metallic plate or a hard plastic material. And, during the molding of second split portion  3 , the coupling portion  5  is integrally molded. Or, the parts may be bonded by use of a bonding agent  14 . 
     The another structure of boot shown in FIG. 7 is approximately identical to the boot  1  shown in FIG. 1, as the parts are shown with the same symbols. And, in the boot  1  shown in FIG. 7, the male coupling portion  4  strongly couples inside the female coupling portion  5  by use of the elastic support portion  16 . 
     FIG. 8 is further a major portion cross sectional view of coupling portion in the boot  1  showing the mode of 3rd embodiment according to this invention. 
     The engaging portion  8  of coupling portion  4  in FIG. 8 is formed to a convex portion of semi-sphere state. This engaging portion  8  exists in one piece, but may also be installed in plural number like two pieces, three pieces, etc. according to the necessity. Further, a part of outer circumference of engaging portion  8  may be cut so as to have an elasticity. 
     On the other hand, the coinciding female portion  13  of female coupling portion  5  for engaging the engaging portion  8  is formed with a punched hole. And the engaging portion  8  of male coupling portion  4  is fitted to and engaged with the coinciding female portion  13  of this hole shape. Further, the mutually bent and opposed side plates  19  are joined so as to enclose the lateral side of acceptance portion  12  to both the sides of acceptance portion  12 . 
     Further, an integral portion  18  by pin is formed inside the acceptance portion  12 , and plays a role of strongly coupling the female coupling portion to the second split portion  3 . This pin shaped integral portion  18  can hold the interval of acceptance portions  12  so that it may not become smaller and can facilitate the insertion of insertion portion  6  of male coupling portion  4 . 
     The merit of boot  1  in FIG. 8 resides in such facts that the shape of respective coupling portions  4  and  5  can be easily fabricated and the cost can be decreased. Namely, the engaging portion  8  can be easily fabricated because it can be formed by press-stamping a steel ball. Further, the coinciding female portion  13  can be quite easily fabricated because it may be a through-hole by the punching or drilling. 
     FIG. 9 is a major portion cross sectional view of coupling portion of boot  1  showing the mode of still another embodiment according to this invention. 
     In FIG. 9, the male coupling portion  4  is formed to a plate shape, and the integral portion  7  coupling with the first split portion  2  at one end side is bent to a semi-circular shape. This integral portion  7  is formed to a semi-circular shape, but may also be formed to an L-shape or a circular shape. In case of the circular shape, a pit may be fitted inside the circular shape. 
     An engaging portion  8  is formed to the insertion portion  6  of male coupling portion  4  protruding out of the first split face  2   a  of first split portion  2 . The coinciding portion  8  having an elasticity to this leaf spring shape is partially cut in the plate shape and bent to an inclination state. This male coupling portion  4  is made of metallic material but can also be made of resin material. 
     FIG. 10 is a plane view of split part  23  on one side of female coupling portion  5 . Further, FIG. 11 is this lateral face view. 
     The female coupling portion  5  made of resin material is buried into the second split portion  3 . The split part  23  on one side formed as shown in the plane view of FIG. 10 is opposed to the split part  24  on the other side formed in the same way with the split part  23  on said one side and not shown in the figure and they are deposited and integrally formed into the formation of this female coupling portion  5  as shown in FIG.  9 . And, a chamfer  12   b  is provided to the insertion inlet  12   a  of acceptance portion  12  and formed so that the male coupling portion  4  can be easily inserted. 
     In the deposition of this female coupling portion  5 , the first deposition portion  25  protruding to a triangle shape in cross section in the split face  29  and the second deposition portion  26  protruding to a conical shape in cross section are mutually deposited flatly to the counterpart split faces  29 , and the acceptance portion  12  is formed to an empty chamber  12   c  as shown in FIG.  9 . Moreover, Numeral  27  is a positioning pin. Further, Numeral  28  is a positioning pin hole fitting with this positioning pin  27 . 
     The coinciding female portion  13  for accepting the engaging portion  8  formed on the male coupling portion  4  is formed to the female coupling portion  5 . And the tip portion  8   a  provided to the engaging portion  8  coincides to the contact portion  13   a  of coinciding female portion  13  and joins the first split face  2   a  with the second split face  3   a.    
     The layout of this male coupling portion  4  and female coupling portion  5  should preferably be integrated into the film in the midway between the crest portion  10  and the valley portion  11  as shown in FIG.  2  and FIG.  3 . For information, the split part  23  on one side and the split part  24  on the other side can also be bonded in addition to the deposition. These parts can also be made of metallic material in addition to the resin material. 
     Because this female coupling portion  5  is formed to a box shape, this portion is convenient for preventing the inflow of mold material during the molding and for integrally being molded with the second split portion  3 . 
     For information, FIG.  4  and FIG. 7 employ such a design similarly to FIG.  8  and obtain a favorable result that the lateral plates bent to the side face of acceptance portion  12  of female coupling portion  5  are opposed to each other and the acceptance portion  12  is enclosed to a square shaped empty chamber. 
     FIG. 12 is a lateral face view showing the coupling portion side in the boot  100  in the pattern of 4th embodiment relating to this invention. 
     In FIG. 12, Numeral  100  stands for a boot. The boot is fabricated by cure-molding the rubber material, but this boot  100  is split at one place in axial direction, and the split face side on one side is separately formed from the first split portion  102  and the split face side on the other side is separately formed from the second split portion  103 . 
     And on the side of first split portion  102 , the coupling portion in the shape as shown in FIG. 13 is formed. In this FIG. 13, a part of male coupling portion is an oblique view. In FIG. 13, the male coinciding portion  118  protruding to a concave portion in its cross section is provided to this coupling portion. Further, a coinciding groove  114  is formed on the root side of lateral face of male coinciding portion  118 . Furthermore, the male coupling portion  104  made of resin material as shown in FIG.  13  and FIG. 14 not only buries the side of larger diameter fixed portion  109  to the first split portion  102  but also the insertion portion  106  is integrally adhered as if it protrudes out to the side of end face  107  of male coinciding portion  118 . FIG. 14 is a plane view of male coupling portion  104 , and FIG. 15 is a lateral face view. 
     In FIG.  14  and FIG. 15, the male coupling portion  104  is structured in such a manner that the coinciding portion  108  formed on the conical shaped top state outside face  110  is not only formed to the tip but this coinciding portion  108  is also engaged with the stage portion  121  fitted to and provided inside the female hole  116  corresponding to the coinciding female portion  113  being described later. The top state outside face  110  is the embodiment mode of engaging portion  108 . 
     It is recognized that the similar function can be exhibited even if this top state outside face  110  should be formed to a spherical shape or a column shape in addition to the conical shape. 
     Further, it is recognized favorable to split the insertion portion  106  by the slitting work to the axial direction from the tip face and to provide an elastic portion for facilitating its insertion. Especially, it is favorable to split the insertion portion into three equal portions. The mode of this favorable embodiment is to be described later. 
     Moreover, it is also recognized more favorable to provide a split portion coinciding with the protruded wedge to the coinciding portion  108  for expanding the coinciding portion  108 , and to coincide it so that it may not get separated from the coinciding female portion  113 . 
     The fixed portion  109  of male coupling portion  104  is interconnected by use of a thin interconnection plate  117 . This interconnection plate  117  is formed to a thin thickness so that it may exhibit its flexibility. However, because this interconnection plate  117  is not a part of the structure of male coupling portion  104  but is an ancillary one, the function is available even if there is no interconnection plate  117 . 
     Further, as shown in FIG. 12, the coupling portion is formed to the side of second split portion  103 . The detailed view of coupling portion is as shown in FIG.  16 . FIG. 16 is an oblique view showing a part of coupling portion. In FIG. 16, the male coinciding portion  118  and the fitting concave state female coinciding portion  119  are formed on the coupling portion. Further, a hook portion  115  is formed on the outside concave shape end portion to this female coinciding portion  119  and is structured in such that it may be inserted together with the engaging groove  114 . 
     Further, to the female coinciding portion  119 , the female coupling portion  105  made of resin material is buried to the bottom face  122  of concave portion and is integrally fixed. 
     This female coupling portion  105  is made of resin material and is formed to the shape shown in FIG.  17  and FIG.  18 . FIG. 17 is a plane view of this female coupling portion  105  and FIG. 18 is its lateral face view. 
     In FIG.  17  and FIG. 18, an acceptance portion  112  is formed on the female coupling portion  105  of cylindrical shape having a bottom, and the stage portion  121  by use of a large diameter female hole corresponding to the coinciding female portion  113  is formed to the interior. This stage portion  121  is structured in such that it may get engaged with the engaging portion  108  formed on the top shape outside face  110 . 
     In the female coupling portion  105 , the respective fixed portions  109  are integrally interconnected with each other by use of the interconnection plate  117 . This interconnection plate  117  is structured in such as exhibiting the flexibility similar to the interconnection plate  117  of male coupling portion  104 . However, this interconnection plate  117  is not a structural part of female coupling portion  105  but is an additional technique. 
     The protrusive wedge coinciding with the split portion of coinciding portion  108  is provided to the bottom face of acceptance portion  112 , and it is recognized favorable if the coinciding portion  108  formed on the top shape outside face  110  should be expanded by the wedge and coincided securely to the stage portion  121 . Further, it is also possible to enter a slit up to the midway along the shaft of acceptance portion  112  into the female coupling portion  105  for providing an elasticity and to make it easier to insert the coinciding portion  108 . 
     The above mentioned male coupling portion  104  and female coupling portion  105  are processed by molding the resin material according to the separate manufacturing process. And, when cure-molding the boot  100 , the male coupling portion  104  and the female coupling portion  105  are arranged inside the molding die for their cure-bonding and integration. 
     The acceptance portion  112  of female coupling portion  105  may also be formed to an oval hole in cross section in addition to the circular hole. And if both the side faces of top shape coinciding portion  108  should be cut for form a parallel face, and if the engaging portion  108  should be inserted into the oval hole from this parallel face and engaged with the stage portion  121 , the insertion becomes easier. 
     FIG. 19 is a cross sectional view showing the coupling status between the coupling portions of both the parties. 
     In FIG. 19, the insertion portion  106  is fitted to the acceptance portion  112  of female coupling portion  105 , and the engaging portion  108  provided on the insertion portion  106  engages to the stage portion  121  of female hole  116  for closely contacting the first split portion  102  to the second split portion  103 . At the same time, by inserting the male coinciding portion  118  into the female coinciding portion  119  and also by coupling the hook portion  115  to the coinciding groove  114 , the prevention of outflow of grease and the like toward the interior can be securely done but the prevention of dust invading from the outside can also be effectively exhibited. For reference, it is also acceptable to intervene the bonding agent to the joint face between the male coinciding portion  118  and the female coinciding portion  119 . 
     Next, the favorable boot as the mode of 5th embodiment is shown in FIG.  21  and FIG.  22 . 
     FIG. 21 is a plane view of split face on the side of larger diameter mounting portion of first split  102  of boot  1 . 
     The male coupling portion  104  having an engaging portion  108  which is wide in width to the longitudinal direction of first split face  102   a  is integrally mounted to the mounting portion of first split face  102   a  and to the split portion between the crest portion and the valley portion. This male coupling portion  104  can be integrated through integral molding or by providing the mounting hole to the boot  100  and fitting its mounting hole to the male coupling portion  104 . 
     FIG. 22 is a plane view of split face on the side of large diameter mounting portion of the second split face  103   a  of boot  100 . To this second split face  103   a , the female coupling portion  105  is installed to the position corresponding to the male coupling portion  104  installed on the first split face  102   a . This female coupling portion  105  is also integrally molded to or adhered to the boot  10  by its fitting. For information, Numeral  132  is a band for mounting the boot  100  to the shaft coupling  130 . 
     FIG. 23 is a cross sectional view taken along the line A—A shown in FIG. 25 in the status coupling the above mentioned male coupling portion  104  with the female coupling portion  105 . 
     In FIG. 23, the fixed portion  109  is not only integrally coupled to the interior of first split portion of boot  100 , but the tip side of protrusive insertion portion  106  also has an inclined face  120   a  on both the sides and is formed to a wide width wedge shape in a right angle direction against the cross sectional view in the male coupling portion  104  made of resin material. And the engaging portion  108  having a stage portion is formed on the side of root. Further, a concave portion  125  leading to the interior from the tip face is formed on the insertion portion  106 . This concave portion  125  penetrates in the wider width direction and is structured in such that the wedge status portion of engaging portion  108  may get elastically deformed for its easier insertion into the female hole  116 . 
     Further, the female coupling portion  105  made of resin material is fixed to the interior of second split portion  103 . This female coupling portion  105  not only has an acceptance portion  112 , but a stage portion  121  engaging with the engaging portion  108  of insertion portion  106  is also formed to the acceptance portion  112 . And the acceptance portion  112  is structured in such a manner that it is formed to an oval hole in a right direction against the cross sectional view and gets coincided with the insertion portion  106 . 
     If this insertion portion  106  should be inserted into the acceptance portion  112 , the insertion portion  106  is elastically deformed by the concave portion  125  for its insertion into the acceptance portion  112 . And, the engaging portion  108  engages to the stage portion  121  of coinciding female portion  113  and makes the first split portion  102  contacted with the second split portion  103 . The entire joined status of both the split portions  102  and  103  shall be made the situation as shown in FIG.  20 . Further, the joining force in circumferential direction can be made stronger by elongating the insertion portion  106  and the acceptance portion  112  in a right angle direction against the cross sectional view. Especially, because the inclined face whose tip side of engaging portion  108  becomes thinner is not only provided but the concave portion  125  is also provided, the insertion portion  106  can be inserted easily and moreover engaged easily. 
     FIG. 25 is a lateral face view before both the split portions  102  and  103  are coupled together. The male coupling portion  104  and the female coupling portion  105  owned on the side of respective split faces  102   a  and  103   a  are integrally coupled in opposition to the first split portion  102  and the second split portion  103  singularly without being coupled with the interconnection plate  117 . This integral coupling molding can be done easily by arranging and molding the male coupling portion  104  and the female coupling portion  105  at the stipulated position inside the molding die. 
     Further, in the mode of this embodiment, the split face in radial direction or the inclined split face having no male engaging portion  118  and female engaging portion  119  in FIG. 12 is closely coupled directly by the male coupling portion  104  and the female coupling portion  105 . 
     Furthermore, in the mode of this embodiment, a concave and a convex portion forming the annular state of semi-sphere may be provided to the inside and outside of boot radial direction of coupling face for their close contact against the male coupling portion  104  and female coupling portion  105 . 
     As shown in FIG. 25, a great number of male coupling portions  104  are arranged and fixed in the state protruding from the insertion portion  106  along the split face on the first split face  102   a . Further, on the second split face  103   a , the entirety of female coupling portion  105  is arranged at the position corresponding to a great number of male coupling portions  104  along the second split face  103   a  so that the entirety may be buried in. FIG. 20 is a plane view assembling the boot  100  to the shaft coupling  130  and the shaft  131 . In FIG. 20, the first and second split faces  102   a  and  103   a  of boot  100  shall be opened and the boot shall be assembled from the side direction of shaft coupling  130 . 
     And, by fitting the male coupling portion  104  into the female coupling portion  105 , the first split face  102   a  and the second split face  103   a  as shown in FIG. 20 become the joined status. Next, the mounting portions of both the end sides shall be tightened by the bands  132  and  133  for their fixation and fitting. 
     FIG. 24 is a view where a convex portion  126  is provided innermost of the acceptance portion  112  of female coupling portion  105  for its fitting with the concave portion  125  so that the insertion portion  106  may be caught mutually to the side of concave portion  125  and the engaging portion  108  and the stage portion  121  may not get separated. The effect of sealing the inside and outside of boot  100  can be exhibited by the joint between this convex portion  126  and the engaging portion  108  on the side of concave portion  125 . In the mode of these embodiments, it may be acceptable to install semi-spherical concave and convex forming an annular state to the side of inside and outside diameters of male coupling portion  104  and female coupling portion  105  of both the split face, for their close contact with each other and for providing the sealing ability. 
     For information, when integrally molding the male coupling portion  104  and the female coupling portion  105  into the formation of boot  100 , it is also possible to coat a bonding agent to the fixed portions  109  and  109 , fitting them to the mounting hole provided on the boot  100  and baking it by the secondary curing in addition to directly baking and molding it inside the above mentioned molding die. 
     Because the boot of this invention is structured in such a way that the male coupling portion structured of the similar material is inserted into the female coupling portion having the elasticity with the hard quality material for engaging the engaging portion to the coinciding female portion, its insertion is easy, and moreover because this engaging portion is engaged mechanically with the coinciding female portion, the separation can be effectively prevented even if the joined split face of boot should be subjected to the outside force. 
     Moreover, because the pull-out engagement between the engaging portion and the coinciding female portion is elastically deformed for their engagement, it becomes possible to couple them with each other so as to pressure contact the first and second split faces with each other. Therefore, it becomes possible to join the mutually joined split faces to a sealed status. 
     Especially it is difficult to mutually join the split faces with each other because the split faces of boot are in bellows status, but it is easy to join the split faces mutually with each other because they are coupled to each other strongly only by pressure contacting the male coupling portion to the female coupling portion. 
     In the boot of this invention, because the engaging portion of male coupling portion having an elasticity is not only engaged to the coinciding female portion but the insertion portion also won&#39;t get contacted strongly with the acceptance portion, only the engaging portion can be pressure contacted with the coinciding female portion. For this reason, even if the first split face and the second split face are not formed to the same plane face, it becomes possible for the engaging portion to get pressure contacted to the coinciding female portion so that the first split face and the second split face may be joined. As a result, the present invention provides such an effect for the sealing force of split faces to be reinforced by seal-joining the first split face with the second split face. 
     The boot of this invention may have the male coupling portion of harder material than the boot arranged and coupled respectively along the axial direction to the coupling portion, and has an engaging portion in protrusion to this male coupling portion. The female coupling portion on the other side is also formed and arranged in such a way that it can be coupled in correspondence to the male coupling portion. For this reason, because the respective coupling portions are arranged so that they may exist sporadically in the axial direction of each split portion, if the male coupling portion should be coupled to the female coupling portion one by one, they can be easily coupled with each other even if the coupling portion should be crooked to a bellows status. Moreover, because the male coupling portion and the female coupling portion are harder in material than the boot, the coupling force of both the parties becomes stronger when they are press-fitted. In addition, because the male coupling portion and the female coupling portion are independent from each other, such an effect can be expected to exhibit the flexibility without aggravating the flexibility of boot even if the male coupling portion and the female coupling portion are harder material. 
     Because the boot of this invention according to may enlarge the male coupling portion and the female coupling portion in one direction, the coupling force in circumferential direction becomes stronger. Further, because a concave portion is provided to the insertion portion and the male coupling portion and the female coupling portion are elongated in the longitudinal direction of split face, the insertion becomes easier when they are to be coupled. 
     In the boot of this invention, because the male coupling portion and the female coupling portion are interconnected by use of the interconnection plate with each other, the positioning of both the parties during the molding is simple, and moreover it becomes possible to couple them strongly with the coupling portions. 
     In the boot of this invention, because the opposing concave portion male coinciding portion and convex portion female coinciding portion are installed to both the coupling portions, the seal joining can be expected if both the coinciding portions should be coupled by means of the male coupling portion and female coupling portion. Moreover, because the coinciding groove and the hook groove existing on both the coinciding portions are fitted with each other, further the sealing effect can be expected.