Patent Publication Number: US-2022228680-A1

Title: Hydraulic adapter unit, hydraulic pipe member, and method for manufacturing hydraulic pipe member

Description:
TECHNICAL FIELD 
     The techniques disclosed herein relate to a hydraulic adapter unit. 
     BACKGROUND ART 
     A hydraulic adapter member for coupling a hose with a hydraulic device has been known. The hydraulic adapter member includes: a tubular pipe body; a mouthpiece portion formed on one end side of the pipe body and to which a hose is caulked and fixed; and a flange portion formed on the other end side of the pipe body to project outward in the radial direction of the pipe body and fixed to the hydraulic device (see, for example, Patent Document 1). 
     CITATION LIST 
     Patent Literature 
     Patent Document1: Japanese Unexamined Patent Application Publication No. H06-229489 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the conventional hydraulic adapter member described above, the pipe body and the mouthpiece portion are integrally formed and inseparable. Therefore, for example, it is difficult or impossible to couple the flange portion of the hydraulic adapter member to the hydraulic device or to replace the hose. 
     This specification discloses techniques capable of solving at least some of the problems described above. 
     Solution to Problem 
     The techniques disclosed herein can be implemented in the following forms. 
     (1) A hydraulic adapter unit disclosed herein is a hydraulic adapter unit for coupling a hose with a hydraulic device, comprising: substantially cylindrical hose connecting member including: a hose fixing portion positioned at one end side of the hose connecting member and to which the hose is fixed; a first combining portion positioned at the other end side of the hose connecting member; and an intermediate portion linking the hose fixing portion and the first combining portion; and a pipe member including: a substantially tubular pipe body; a second combining portion disposed at the one end side of the pipe body and separably combined to the first combining portion of the hose connecting member; and a flange portion disposed at the other end side of the pipe body and formed so as to project outward in the radial direction of the pipe body and fixed to the hydraulic device. 
     In the hydraulic adapter unit, the hose connecting member to which a hose is fixed and the pipe member having the flange portion fixed to the hydraulic device are separably combined to each other. Thus, by separating the hose connecting member and the pipe member, the fixing work of the pipe member to the hydraulic device or the fixing work of the hose to the hose connecting member can be carried out independently. In other words, the present hydraulic adapter unit improves workability in coupling of the hose with the hydraulic device. 
     (2) In the hydraulic adapter unit, the first combining portion of the hose connecting member may have a male screw portion formed on an outer peripheral surface of the hose connecting member; and the second combining portion of the pipe member may have a female screw portion formed on an inner peripheral surface of the pipe member and screwed to the male screw portion of the first combining portion. 
     In the present hydraulic adapter unit, since the second combining portion of the pipe member has the female screw portion, it is possible to suppress the leakage of the hydraulic oil supplied from the hose to the hydraulic device from the portion between the hose connecting member and the pipe member as compared with a configuration in which the second combining portion has a male screw portion. 
     (3) In the hydraulic adapter unit, the second combining portion of the pipe member may be substantially annular and may include: one end portion positioned at the one end side of the second combining portion and having the female screw portion formed on the inner peripheral side; and the other end portion which is positioned at the other end side of the second combining portion and to which the pipe body is inserted and joined on the inner peripheral side, wherein the thickness of the one end portion may be greater than the thickness of the other end portion and greater than the thickness of the pipe body, and the thickness of the other end portion may be closer to the thickness of the pipe body than the thickness of the one end portion. In the hydraulic adapter unit, the thickness of one end portion of the second combining portion of the pipe member is thicker than the thickness of the other end portion or the pipe body. Therefore, for example, it is possible to improve the strength of the one end portion where the female screw portion is formed as compared with a configuration in which the thickness of the one end portion is as thin as the thickness of the other end portion. On the other hand, the thickness of the other end portion is closer to the thickness of the pipe body than the thickness of the one end portion. Therefore, the second combining portion (pipe member) can be reduced in size and weight as compared with a configuration in which the thickness of the other end portion is as large as the thickness of the one end portion. Further, for example, as compared with a configuration in which the thickness of the other end portion is closer to the thickness of the one end portion than the thickness of the pipe body, it is possible to suppress stress concentration which would otherwise be caused by the difference in thickness between the other end portion and the pipe body. 
     (4) In the hydraulic adapter unit, the outer diameter of the other end portion may be smaller than the outer diameter of the one end portion, and the outer peripheral surface of the other end portion may be substantially parallel to the axial direction of the second combining portion. In the hydraulic adapter unit, the other end of the second combining portion of the pipe member to which the pipe body is connected has an outer diameter smaller than that of the one end. The outer peripheral surface of the other end portion is substantially parallel to the axial direction of the second combining portion. Therefore, as compared with, for example, a configuration in which the outer diameter of the other end portion is relatively large, or a configuration in which the outer peripheral surface of the other end portion is inclined with respect to the axial direction, it is possible to relax stress concentration at the portion at which the pipe body is joined with the second combining portion while limiting the size of the second combining portion. 
     (5) In the hydraulic adapter unit, the second combining portion of the pipe member may have a tapered portion linking the one end portion and the other end portion and having an outer diameter continuously decreasing from the one end portion toward the other end portion. In the hydraulic adapter unit, the second combining portion of the pipe member has a tapered portion linking the one end portion and the other end portion, and the tapered portion has an outer diameter continuously decreasing from the one end portion to the other end portion. Therefore, as compared with a configuration in which a step is formed between one end portion and the other end portion, it is possible to relax stress concentration between the one end portion and the other end portion and avoid a thin-walled portion to be formed at the second combining portion due to the existence of the step. 
     (6) In the hydraulic adapter unit, the intermediate portion of the pipe body in the pipe member may have a bent portion having a bent shape. In this hydraulic adapter unit, a pipe body in a pipe member has a bent portion. In such a configuration in which the pipe body of the pipe member has a bent portion, for example, the bent portion interfere the fixing work of the hose to the hose connecting member, thereby making the fixing work to be impossible or difficult. With regard to this, in the present hydraulic adapter unit, by separating the hose connecting member and the pipe member, the hose can be fixed to the hose connecting member without being interfered by the bent portion of the pipe member. 
     (7) A hydraulic pipe member disclosed herein is a hydraulic pipe member for coupling a hydraulic device with a hose connecting member having one end side to which a hose is fixed and the other end side on which a first combining portion is formed, comprising: a tubular pipe body; a second combining portion disposed on the one end side of the pipe body and separably combined to the first combining portion of the hose connecting member; and a flange portion disposed on the other end side of the pipe body and formed to project outward in the radial direction of the pipe body and fixed to the hydraulic device. The present hydraulic pipe member can improve the workability of the coupling of the hose with the hydraulic device. 
     (8) In the above hydraulic pipe member, the second combining portion of the hydraulic pipe member may be substantially annular and may include: one end portion positioned at the one end side of the second combining portion and having a female screw portion formed on the inner peripheral side, which can be screwed to a male screw portion of the first combining portion; and the other end portion positioned at the other end side of the second combining portion and to which the pipe body is inserted and joined on the inner peripheral side; and the thickness of the one end portion may be greater than the thickness of the other end portion and greater than the thickness of the pipe body, and the thickness of the other end portion may be closer to the thickness of the pipe body than the thickness of the one end portion. 
     (9) In the above hydraulic pipe member, the outer diameter of the other end portion may be smaller than the outer diameter of the one end portion, and the outer peripheral surface of the other end portion may be substantially parallel to the axial direction of the second combining portion. 
     (10) In the above hydraulic pipe member, the second combining portion may have a tapered portion linking the one end portion and the other end portion and having an outer diameter continuously decreasing from the one end portion toward the other end portion. 
     (11) A method for manufacturing a hydraulic pipe member disclosed herein is a method for manufacturing a hydraulic pipe member including a tubular pipe body and a second combining portion disposed on one end side of the pipe body and separably combined to a first combining portion of a hose connecting member to which a hose is fixed, comprising: a preparation step of preparing the pipe body and the second combining portion, wherein the second combining portion is substantially annular, and includes: one end portion positioned at the one end side of the second combining portion and having a female screw portion formed on the inner peripheral side, which can be screwed to a male screw portion of the first combining portion, and the other end portion positioned at the other end side of the second combining portion and having a thickness thinner than the thickness of the one end portion; a joining step of inserting the pipe body into the inner peripheral side of the other end portion of the second combining portion, and disposing a brazing material in the vicinity of the inner peripheral side of the other end portion, and performing a high-frequency induction heating treatment by flowing an alternating current to a first coil surrounding the pipe body, a second coil surrounding the other end portion, and a third coil surrounding the one end portion. According to the present method for manufacturing a hydraulic pipe member, it is possible to prevent the occurrence of a joint failure between the pipe body and the other end portion which would be caused in a case where the heat generated at the other end portion escapes to the one end portion. 
     The techniques disclosed herein can be implemented in a variety of forms, such as, for example, a hydraulic adapter unit, a hydraulic pipe member, a hydraulic hose connecting member, and a manufacturing methods of them, and a method of coupling a hose with a hydraulic device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an explanatory view illustrating an XZ cross-sectional configuration of a hydraulic adapter unit  10  according to a first embodiment. 
         FIG. 2  is an explanatory view illustrating an XZ plane configuration of a mouthpiece  100  and a pipe member  200  according to the first embodiment. 
         FIG. 3  is an explanatory view illustrating an XZ plane configuration of a hydraulic adapter unit  10   a  according to a comparative example. 
         FIG. 4  is an explanatory view illustrating an XZ cross-sectional configuration of a pipe member  200 X according to a second embodiment. 
         FIG. 5  is an explanatory view illustrating an XZ plane configuration of the pipe member  200 X according to the second embodiment. 
         FIG. 6  is a flow chart illustrating a method for manufacturing the pipe member  200 X. 
         FIG. 7  is an explanatory view illustrating a part of a manufacturing process of the pipe member  200 X. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A. First Embodiment: 
     A-1. Configuration of Hydraulic Adapter Unit  10 : 
       FIG. 1  is an explanatory view illustrating an XZ cross-sectional configuration of a hydraulic adapter unit  10  according to a first embodiment, and  FIG. 2  is an explanatory view illustrating an XZ plane configuration of a mouthpiece  100  and a pipe member  200  according to the first embodiment.  FIG. 1  shows the hydraulic adapter unit  10  in a state in which the mouthpiece  100  and the pipe member  200  are connected, and  FIG. 2  shows the hydraulic adapter unit  10  in a state in which the mouthpiece  100  and the pipe member  200  are separated. In each view, mutually orthogonal XYZ axes for specifying directions are shown. Although the positive Z-axis direction is referred to herein as an upward direction and the negative Z-axis direction is referred to herein as a downward direction for convenience, the hydraulic adapter unit  10  may actually be installed in a direction different from such a direction. The same applies to  FIG. 3  and subsequent figures. 
     As shown in  FIG. 1 , the hydraulic adapter unit  10  couples the hose  60  with the hydraulic device  50  to allow hydraulic fluid to be supplied from the hose  60  to the hydraulic device  50 . The hydraulic device  50  is, for example, a device for driving a hydraulic pump (not shown) by an external drive source (electric motor or engine) to operate an actuator (for example, hydraulic motor or hydraulic cylinder) by a hydraulic fluid (hydraulic oil) having a pressure generated by the hydraulic pump. Examples of the hydraulic device  50  include: construction machines such as hydraulic excavators; industrial vehicles such as forklifts; agricultural machines such as tractors; specially equipped vehicles such as dump trucks; general industrial machines such as iron making machines, machining tools, and injection molding machines; and seismic isolation devices for buildings. In this embodiment, the hose  60  is a hose for high pressure, and is formed of, for example, rubber or resin. One end of the hose  60  is connected to an oil supply (not shown). Hereinafter, with regard to each member, the hose  60  side is referred to as the “proximal end”, and the hydraulic device  50  side is referred to as the “distal end”. 
     As shown in  FIGS. 1 and 2 , the hydraulic adapter unit  10  includes a mouthpiece  100  and a pipe member  200 , and as described later, the mouthpiece  100  and the pipe member  200  can be separated from each other (see  FIG. 2 ). The mouthpiece  100  corresponds to the hose connecting member in the claims. 
     Configuration of Mouthpiece  100   
     The mouthpiece  100  is a substantially cylindrical member as a whole, and has a mouthpiece through-hole  102  formed therein and penetrating from the proximal end to the distal end. The mouthpiece through-hole  102  is a hole extending substantially straightly along the axial direction of the mouthpiece  100 . The mouthpiece  100  includes a hose fixing portion  110 , a mouthpiece side combining portion  120 , and an intermediate portion  130 . The hose fixing portion  110 , the mouthpiece side combining portion  120 , and the intermediate portion  130  are integrally formed of, for example, metal, steel material (carbon steel, alloy steel, stainless steel, or the like), or resin, among other materials. The mouthpiece side combining portion  120  corresponds to the first combining portion in the claims. 
     The hose fixing portion  110  is disposed on the proximal end side (hose  60  side) of the mouthpiece  100 . The hose fixing portion  110  has an inner cylindrical portion  112  having a substantially cylindrical shape and an outer cylindrical portion  114  having a substantially cylindrical shape and disposed so as to surround the inner cylindrical portion  112 . The inner peripheral surface of the inner cylindrical portion  112  constitutes the mouthpiece through-hole  102 . The outer diameter of the inner cylindrical portion  112  is smaller than the outer diameter of the intermediate portion  130 . The inner diameter of the outer cylindrical portion  114  is larger than the outer diameter of the inner cylindrical portion  112 . Therefore, a groove  116  is formed between the inner cylindrical portion  112  and the outer cylindrical portion  114 . The groove  116  extends from the proximal end of the mouthpiece  100  toward the distal end (pipe member  200  side). The groove  116  has a substantially annular shape in the axial view of the mouthpiece  100 . The distal end portion of the hose  60  is inserted into the groove  116 , and is caulked with the hose fixing portion  110  (outer cylindrical portion  114 ) by a caulking tool (not shown). Therefore, the distal end portion of the hose  60  is sandwiched and fixed between the inner cylindrical portion  112  and the outer cylindrical portion  114 . The inner cylindrical portion  112  protrudes from the outer cylindrical portion  114  toward the hose  60 . The outer peripheral surface of the outer cylindrical portion  114  forms a part of the outer peripheral surface of the mouthpiece  100 . 
     The mouthpiece side combining portion  120  is disposed on the distal end side (hydraulic device  50  side) of the mouthpiece  100 . The mouthpiece side combining portion  120  has a male screw portion  122  formed on the outer peripheral surface of the mouthpiece  100 . The intermediate portion  130  is disposed between the hose fixing portion  110  and the mouthpiece side combining portion  120  to link them. The outer shape of the intermediate portion  130  in the axial direction is polygonal (e.g., hexagonal). The outer diameter of the intermediate portion  130  is substantially the same as the outer diameter of the hose fixing portion  110 . 
     As shown in  FIG. 2 , a seal member (O-ring  150 ) is fitted to the outer peripheral surface of a portion of the mouthpiece  100  between the male screw portion  122  and the intermediate portion  130 . 
     Configuration of Pipe Member  200   
     The pipe member  200  includes a pipe body  210 , a pipe side combining portion  220 , and a flange portion  230 . The pipe body  210 , the pipe side combining portion  220 , and the flange portion  230  are integrally formed of, for example, metal, steel material (carbon steel, alloy steel, stainless steel, or the like), or resin, among other materials. The pipe side combining portion  220  corresponds to the second combining portion in the claims. 
     The pipe body  210  is substantially tubular and has a pipe through-hole  212  formed therein and penetrating from the proximal end to the distal end of the pipe body  210 . The length of the pipe body  210  in the axial direction is longer than the length of the mouthpiece  100  in the axial direction. The pipe body  210  has a bent portion  214 . In this embodiment, the bent portion  214  is bent so that an angle formed by a pair of straight portions  216 ,  218  located on both sides of the bent portion  214  is approximately 90 degrees. 
     The pipe side combining portion  220  is disposed on the proximal end side (the mouthpiece  100  side) of the pipe body  210 . The pipe side combining portion  220  has a substantially annular shape (nut-like shape) with a nut through-hole  222  formed therein. The proximal end portion of the pipe body  210  is inserted and fixed to the inner peripheral surface (nut through-hole  222 ) on the distal end side of the pipe side combining portion  220 . The pipe body  210  may be fixed to the pipe side combining portion  220  by press-fitting, for example, but it is particularly preferable that the pipe body is firmly fixed by frictional compression bonding. On the inner peripheral surface (the nut through-hole  222 ) on the proximal end side of the pipe side combining portion  220 , a female screw portion  224  is formed. The female screw portion  224  can be screwed to the male screw portion  122  formed on the mouthpiece  100 . Therefore, the mouthpiece side combining portion  120  of the mouthpiece  100  and the pipe side combining portion  220  of the pipe member  200  are separably combined to each other. When the mouthpiece side combining portion  120  and the pipe side combining portion  220  are combined, the O-ring  150  is sandwiched between them. Thus, the gap between the mouthpiece  100  and the pipe member  200  is sealed to prevent the leakage of the hydraulic oil. 
     In order to secure the strength of the pipe side combining portion  220 , the thickness (the distance between the inner peripheral surface and the outer peripheral surface) of the pipe side combining portion  220  is greater than the thickness (the distance between the inner peripheral surface and the outer peripheral surface) of the pipe body  210 . Further, the outer diameter of the pipe side combining portion  220  is larger than the outer diameter of the pipe body  210 . The pipe side combining portion  220  is disposed at a position separated from the bent portion  214  of the pipe body  210 , in other words, at the straight portion  216  of the pipe body  210  on the mouthpiece  100  side. The outer shape of the pipe side combining portion  220  in the axial direction is polygonal (e.g., hexagonal). Thus, since the outer shape of the intermediate portion  130  in the axial direction and the outer shape of the pipe side combining portion  220  in the axial direction are both polygonal, they can be screwed firmly using a fastening jig (not shown) as compared with a configuration in which the outer shapes are circular. 
     The flange portion  230  is disposed on the distal end side (hydraulic device  50  side) of the pipe body  210 . The flange portion  230  is formed to project outward in the radial direction of the pipe body  210 . The flange portion  230  has a substantially circular flat plate shape in the axial view of the pipe body  210 . The flange portion  230  has a facing surface  232  disposed to face a wall surface  52  of the housing of the hydraulic device  50 . The facing surface  232  of the flange portion  230  is disposed on the wall surface  52  of the hydraulic device  50  so that the pipe through-hole  212  of the pipe body  210  communicates with an introduction hole  51  formed on the wall surface  52  of the hydraulic device  50 . On the facing surface  232  of the flange portion  230 , there are formed a plurality of recessed portions  234  into which a plurality of projecting portions  56  formed on the wall surface  52  of the hydraulic device  50  are respectively inserted, so that the flange portion  230  is positioned with respect to the hydraulic device  50  by engagement of the plurality of projecting portions  56  and the plurality of recessed portions  234 . 
     The flange portion  230  of the pipe member  200  is fixed to the hydraulic device  50  by a pressing member  20 . Specifically, the pressing member  20  is a substantially flat member that covers a opposite surface  236  on the side opposite to the facing surface  232  and a side surface  238  of the flange portion  230 . In the pressing member  20 , a plurality of bolt holes  28  are formed, and bolts  30  inserted into the plurality of bolt holes  28  are screwed into screw holes  54  formed in the wall surface of the hydraulic device  50 , whereby the flange portion  230  is fixed to the hydraulic device  50 . The pressing member  20  may be formed of a single component (so-called square flange) or a plurality of components (so-called split flange). 
     A-2. Effect of the Present Embodiment: 
       FIG. 3  is an explanatory view illustrating an XZ plane configuration of the hydraulic adapter unit  10   a  according to a comparative example. As shown in  FIG. 3 , the hydraulic adapter unit  10   a  according to the comparative example includes: a tubular pipe body  210   a ; a mouthpiece portion  100   a  formed on one end side of the pipe body  210   a  and to which the hose  60  is fixed; and a flange portion  230   a  formed on the other end side of the pipe body  210   a  so as to project outward in the radial direction of the pipe body  210   a  and fixed to the hydraulic device  50 . In the hydraulic adapter unit  10   a , the pipe body  210   a , the mouthpiece portion  100   a , and the flange portion  230   a  are integrally formed and inseparable. Therefore, in the hydraulic adapter unit  10   a  in the comparative example, when the hose  60  fixed to the mouthpiece portion  100   a  deteriorates and needs to be replaced, the entire hydraulic adapter unit  10   a  has to be replaced. When fixing the hose  60  to the mouthpiece portion  100   a  of the hydraulic adapter unit  10   a , the pipe body  210   a  and the flange portion  230   a  interfere the work, so that it is difficult or impossible to perform caulking using a caulking tool. In the hydraulic adapter unit  10   a  according to the comparative example, the pipe body  210   a  has a bent portion  214   a . Therefore, the presence of the bent portion  214   a  further makes it difficult or impossible to carry out the caulking. 
     On the contrary, in the hydraulic adapter unit  10  according to the present embodiment, the mouthpiece  100  to which the hose  60  is fixed and the pipe member  200  having the flange portion  230  fixed to the hydraulic device  50  are separably combined to each other (see  FIGS. 1 and 2 ). Thus, by separating the mouthpiece  100  and the pipe member  200 , the fixing work of the pipe member  200  to the hydraulic device  50  or the fixing work of the hose  60  to the mouthpiece  100  can be carried out independently. In other words, according to the present embodiment, it is possible to improve the workability of the coupling between the hose  60  and the hydraulic device  50 . 
     Further, in the present embodiment, since the pipe side combining portion  220  of the pipe member  200  has the female screw portion  224 , the hydraulic oil supplied from the hose  60  to the hydraulic device  50  can be prevented from leaking out from the portion between the mouthpiece  100  and the pipe member  200  as compared with a configuration in which the pipe side combining portion  220  has a male screw portion. Further, in the pipe member  200  in which the mouthpiece  100  is removed from the hose and left fixed to the hydraulic device  50  when replacing the hose, the screw portion is not exposed to the outside, so that it is possible to prevent, for example, the damage of the screw portion which would otherwise be caused by receiving an impact from the outside. 
     In this embodiment, the pipe body  210  of the pipe member  200  has the bent portion  214 . In such a configuration in which the pipe body  210  of the pipe member  200  has the bent portion  214  as described above, for example, the bent portion  214  interfere the fixing work of the hose  60  to the mouthpiece  100 , thereby making the fixing work to be impossible or difficult. With regard to this, in the present embodiment, by separating the mouthpiece  100  and the pipe member  200 , the hose  60  can be fixed to the mouthpiece  100  without being interfered by the bent portion  214  of the pipe member  200 . 
     B. Second Embodiment: 
     B-1. Configuration of Pipe Member  200 X: 
       FIG. 4  is an explanatory view illustrating an XZ cross-sectional configuration of a pipe member  200 X according to a second embodiment, and  FIG. 5  is an explanatory view illustrating an XZ plane configuration of the pipe member  200 X according to the second embodiment. The pipe member  200 X of the second embodiment is a member for coupling the mouthpiece  100  with the hydraulic device  50  as with the pipe member  200  of the first embodiment. The same components of the pipe member  200 X as those of the pipe member  200  of the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted. 
     The pipe member  200 X includes a pipe body  210 X, a pipe side combining portion  220 X, and a flange portion  230 . The pipe body  210 X, the pipe side combining portion  220 X, and the flange portion  230  are each formed of, for example, a metal or a steel material (carbon steel, alloy steel, stainless steel, or the like). The pipe side combining portion  220 X corresponds to the second combining portion in the claims. 
     The pipe side combining portion  220 X is disposed at the proximal end side of the pipe body  210 X (the mouthpiece  100  side in  FIG. 1 ). The pipe side combining portion  220 X has a substantially annular shape (nut-like shape) with a nut through-hole  222 X formed therein. The pipe side combining portion  220 X has a thick-walled portion  225 , a thin-walled portion  226  and a tapered portion  227 . The thick-walled portion  225  corresponds to one end portion in the claims, and the thin-walled portion  226  corresponds to the other end portion in the claims. 
     The thick-walled portion  225  is positioned at the proximal end side of the pipe side combining portion  220 X (the mouthpiece  100  side in  FIG. 1 ). The outer peripheral surface of the thick-walled portion  225  is substantially parallel to the axial direction (X-axis direction in  FIG. 4 ) of the pipe side combining portion  220 X. In this specification, “A and B are substantially parallel” means that the angle difference between A and B is ±5 degrees or less (the same applies hereinafter). On the inner peripheral surface of the thick-walled portion  225 , the female screw portion  224  is formed. In this embodiment, the outer shape of the thick-walled portion  225  in the axial direction is substantially circular. However, the outer shape of the thick-walled portion  225  in the axial direction may be, for example, a polygon (e.g., hexagon). 
     The thin-walled portion  226  is located on the distal end side (the pipe body  210 X side) of the pipe side combining portion  220 X. The outer diameter (diameter of the circumscribed circle) of the thin-walled portion  226  is smaller than the outer diameter (diameter of the circumscribed circle) of the thick-walled portion  225 . The outer peripheral surface of the thin-walled portion  226  is substantially parallel to the axial direction (X-axis direction in  FIG. 4 ) of the pipe side combining portion  220 X. In this embodiment, the outer shape of the thin-walled portion  226  in the axial direction is substantially circular. However, the outer shape of the thin-walled portion  226  in the axial direction may be, for example, a polygon (e.g., hexagon). The thickness T 1  of the thick-walled portion  225  in the radial direction is larger than the thickness T 2  of the thin-walled portion  226  in the radial direction and larger than the thickness T 3  of the pipe body  210 X in the radial direction. The thickness T 2  of the thin-walled portion  226  is closer to the thickness T 3  of the pipe body  210 X than the thickness T 1  of the thick-walled portion  225 . In this embodiment, the thickness T 2  of the thin-walled portion  226  and the thickness T 3  of the pipe body  210 X are substantially the same. The thickness T 1  of the thick-walled portion  225  in the radial direction is 2 times or more of the thickness T 2  of the thin-walled portion  226  or the thickness T 3  of the pipe body  210 X. 
     The tapered portion  227  is positioned between the thick-walled portion  225  and the thin-walled portion  226  in the axial direction (X-axis direction in  FIG. 4 ), and links the thick-walled portion  225  and the thin-walled portion  226 . The outer diameter of the tapered portion  227  continuously decreases from the thick-walled portion  225  to the thin-walled portion  226 . The outer peripheral surface of the tapered portion  227  is formed flush with the outer peripheral surface of the thin-walled portion  226 . That is, in the outer peripheral surface of the pipe side combining portion  220 X, the outer peripheral surface formed by the tapered portion  227  and the thin-walled portion  226  are smooth curved surfaces without steps or corners. In the present embodiment, the outer peripheral surface of the tapered portion  227  is a concave curved and inclined surface, but may be a straightly inclined surface or a stepwise inclined surface. 
     In the present embodiment, with regard to the nut through-hole  222 X of the pipe side combining portion  220 X, the diameter D 1  of the proximal end side hole into which the mouthpiece side combining portion  120  of the mouthpiece  100  is inserted is larger than the diameter D 2  of the distal end side hole into which the pipe body  210 X is inserted. On the inner peripheral side of the pipe side combining portion  220 X, there is formed a rib  228  positioned between the proximal end side hole and the distal end side hole and projecting toward the center of the pipe side combining portion  220 X. The proximal end face of the pipe body  210 X is positioned by abutting on this rib  228 . A step portion (near the rib  228 ) between the proximal end side hole and the distal end side hole is positioned at the inner peripheral side of the tapered portion  227 . 
     B-2. Method for Manufacturing Pipe Member  200 X: 
       FIG. 6  is a flowchart illustrating a method for manufacturing the pipe member  200 X, and  FIG. 7  is an explanatory view illustrating a part of a manufacturing process of the pipe member  200 X. For convenience, the heating unit  330  described later is shown by a virtual line. 
     First, the pipe body  210 X, the pipe side combining portion  220 X, and the flange portion  230  described above are prepared (S 110 ). This step corresponds to the preparation step in the claims. The pipe body  210 X, the pipe side combining portion  220 X, and the flange portion  230  can be formed by casting, for example. 
     Next, the pipe body  210 X and the pipe side combining portion  220 X are joined (S 120 ). This step corresponds to the joining step in the claims. That is, the pipe body  210 X is inserted into the inner peripheral side of the thin-walled portion  226  of the pipe side combining portion  220 X, a brazing material  310  is disposed in the vicinity of the inner peripheral side of the thin-walled portion  226 , and a high-frequency induction heating treatment is performed by flowing an alternating current to a heating unit  330  (a first coil  332 , a second coil  334 , and a third coil  336 ) disposed so as to surround the thin-walled portion  226 . 
     Specifically, as shown in  FIG. 7 , a high-frequency brazing machine (a high-frequency induction heating device) is used. For example, the pipe side combining portion  220 X is placed on a table  300  of the high-frequency brazing machine. In this placement, the pipe side combining portion  220 X is arranged so that the thick-walled portion  225  is positioned at the lower side and the thin-walled portion  226  is positioned at the upper side. Next, the brazing material  310  (for example, annular silver braze) is disposed in the peripheral portion of the opening of the thin-walled portion  226 . Thereafter, the annular heating unit  330  provided in the high-frequency brazing machine is disposed so as to surround the whole periphery of at least the tapered portion  227  in the pipe side combining portion  220 X. In this case, the heating unit  330  is provided therein with three coils (the first coil  332 , the second coil  334 , and the third coil  336 ) arranged vertically. The first coil  332  is disposed so as to surround the periphery of the pipe body  210 X. The second coil  334  is disposed so as to surround the periphery of the thin-walled portion  226  of the pipe side combining portion  220 X. The third coil  336  is disposed so as to surround the periphery of the thick-walled portion  225  of the pipe side combining portion  220 X. 
     The first coil  332 , the second coil  334 , and the third coil  336  have substantially the same cross-sectional areas (cross sections) perpendicular to the axial direction. Further, the inner diameter of the first coil  332  and the inner diameter of the second coil  334  are substantially the same, and the inner diameter of the third coil  336  is larger than the inner diameter of the first coil  332  and the inner diameter of the second coil  334 . Therefore, in the radial direction of  220 X, the distance between the first coil  332  and the pipe body  210 X, the distance between the second coil  334  and the thin-walled portion  226 , and the distance between the third coil  336  and the thick-walled portion  225  are substantially the same. In the vertical direction (Z-axis direction), the distance between the second coil  334  and the third coil  336  is longer than the distance between the first coil  332  and the second coil  334 . In the heating unit  330 , the first coil  332 , the second coil  334 , and the third coil  336  are covered with an insulating material. 
     Next, the straight portion  216  of the pipe body  210  is inserted via the heating unit  330  and the brazing material  310  to the inner peripheral side of the thin-walled portion  226  of the pipe side combining portion  220 X. Thus, an assembly  200 P before joining the pipe body  210 X and the pipe side combining portion  220 X is formed. Then, the high-frequency brazing machine is activated to flow an alternating current to the heating unit  330  (the coils  332 ,  334 ,  336 ), whereby the pipe body  210 X and the thin-walled portion  226  of the pipe side combining portion  220 X generate heat by self-heating. 
     As described above, since the thick-walled portion  225  is thicker than the thin-walled portion  226 , the heat generated in the thin-walled portion  226  easily escaped to the thick-walled portion  225 , and the thin-walled portion  226  might not be heated to the same temperature as the pipe body  210 X. However, in this embodiment, since the thick-walled portion  225  of the pipe side combining portion  220 X also generates heat by self-heating caused by the third coil  336 , the thin-walled portion  226  can be sufficiently heated. By heating the pipe body  210 X and the thin-walled portion  226 , the brazing material  310  melts and enters between the thin-walled portion  226  and the pipe body  210 X. Thus, the pipe body  210 X and the pipe side combining portion  220 X are brazed to be firmly joined. Before heating by the heating unit  330 , brazing flux may be applied to at least one of the pipe body  210  and the thin-walled portion  226  of the pipe side combining portion  220 X. Thus, the oxide film between the pipe body  210  and the pipe side combining portion  220 X is removed, and both can be joined more firmly. 
     The thin-walled portion  226  in the pipe side combining portion  220 X has an outer diameter smaller than the outer diameter of the thick-walled portion  225 , and the outer peripheral surface is substantially parallel to the axial direction of the pipe side combining portion  220 X. Therefore, for example, as compared with a configuration in which the outer diameter of the thin-walled portion  226  is relatively large or a configuration in which the outer peripheral surface of the thin-walled portion  226  is inclined with respect to the axial direction, the thin-walled portion  226  can be heated efficiently and uniformly, so that the pipe body  210  and the pipe side combining portion  220 X can be joined more firmly. 
     Next, the pipe body  210 X and the flange portion  230  are joined (S 130 ). The pipe body  210 X and the flange portion  230  can be joined by a known joining method or the joining method in step  120 , among other methods. Thus, the manufacture of the pipe member  200 X is completed. It should be noted that, before the processing in step  120 , the pipe body  210 X and the flange portion  230  may be joined together in advance. 
     B-3. Effect of the Present Embodiment: 
     In this embodiment, with regard to the pipe side combining portion  220 X of the pipe member  200 X, the thickness T 1  of the thick-walled portion  225  is thicker than the thickness T 2  of the thin-walled portion  226  and the thickness T 3  of the pipe body  210 X (see  FIG. 4 ). Thus, for example, as compared with the constitution in which the thickness T 1  of the thick-walled portion  225  is as thin as the thickness T 2  of the thin-walled portion  226 , it is possible to improve the strength of the thick-walled portion  225  where the female screw portion  224  is formed. On the other hand, the thickness T 2  of the thin-walled portion  226  is closer to the thickness T 3  of the pipe body  210 X than the thickness T 1  of the thick-walled portion  225 . Therefore, as compared with a configuration in which the thickness T 2  of the thin-walled portion  226  is as thick as the thickness T 1  of the thick-walled portion  225 , it is possible to reduce the size and weight of the pipe side combining portion  220 X (the pipe member  200 X). Further, for example, as compared with a configuration in which the thickness T 2  of the thin-walled portion  226  is closer to the thickness T 1  of the thick-walled portion  225  than the thickness T 3  of the pipe body  210 X, it is possible to suppress stress concentration which would otherwise be caused by the thickness difference between the thin-walled portion  226  and the pipe body  210 X. For example, it is possible to prevent damage which would otherwise be caused by stress concentration at a predetermined portion of the thin-walled portion  226  due to the hydraulic pressure (e.g., 350 kPa) or pressure changes of the hydraulic fluid flowing through the pipe member  200 X. 
     In the present embodiment, in the pipe side combining portion  220 X of the pipe member  200 X, the thin-walled portion  226  to which the pipe body  210 X is joined has an outer diameter smaller than that of the thick-walled portion  225 . In addition, the outer peripheral surface of the thin-walled portion  226  is substantially parallel to the axial direction of the pipe side combining portion  220 X. Therefore, as compared with, for example, a configuration in which the outer diameter of the thin-walled portion  226  is relatively large or a configuration in which the outer peripheral surface of the thin-walled portion  226  is inclined with respect to the axial direction, it is possible to relax stress concentration at the portion at which the pipe body  210 X is joined with the pipe side combining portion  220 X while limiting the size of the pipe side combining portion  220 X. 
     In the present embodiment, the pipe side combining portion  220 X of the pipe member  200 X has a tapered portion  227  linking the thick-walled portion  225  and the thin-walled portion  226 , and the tapered portion  227  has an outer diameter continuously decreasing from the thick-walled portion  225  toward the thin-walled portion  226 . As a result, as compared with, for example, a configuration in which a step is formed between the thick-walled portion  225  and the thin-walled portion  226 , it is possible to relax stress concentration between the thick-walled portion  225  and the thin-walled portion  226  and avoid a thin-walled portion with low strength to be formed at the pipe side combining portion  220 X due to the existence of the step. 
     C. Modifications: 
     The techniques disclosed herein are not limited to the embodiments described above, but may be modified in various forms without departing from the spirit and scope thereof, and the following modifications, for example, are also possible. 
     The configuration of the hydraulic adapter unit  10 , the mouthpiece  100 , or the pipe members  200 ,  200 X in the above embodiment is merely an example and can be variously modified. For example, the mouthpiece  100  may be a substantially square cylindrical member. The mouthpiece  100  may have a shape having a bent portion. The outer shape of the intermediate portion  130  and the pipe side combining portion  220  in the axial direction may be, for example, substantially circular. 
     In the above embodiment, the bent portion  214  may be a rectangularly bent portion (L-shape) or a curved portion (C-shape). Specifically, the angle formed by the pair of straight portions  216 ,  218  in the bent portion  214  of the pipe body  210 ,  210 X may be, for example, about 30 degrees, about 45 degrees, about 60 degrees, about 90 degrees, or about 120 degrees. Further, the pipe body  210 ,  210 X may be a substantially straight tubular member. 
     In the above embodiment, the mouthpiece  100  may have a female screw portion and the pipe member  200  may have a male screw portion. Alternatively, the mouthpiece  100  and the pipe member  200  may be formed with respective male screw portions and the mouthpiece  100  and the pipe member  200  may be separably combined to each other by a nut member (not shown) formed with a pair of female screw portions screwed to each of the male screw portion of the mouthpiece  100  and the male screw portion of the pipe member  200 . Alternatively, the mouthpiece  100  and the pipe member  200  may be formed with respective female screw portions and the mouthpiece  100  and the pipe member  200  may be separably combined to each other by a nut member (not shown) formed with a pair of male screw portions screwed to each of the female screw portion of the mouthpiece  100  and the female screw portion of the pipe member  200 . In addition, the mouthpiece  100  and the pipe member  200  may be separably combined by a combining mechanism other than the screw mechanism (for example, a fitting mechanism or an engagement mechanism). 
     In the above embodiment, the flange portion  230  of the pipe member  200  may be formed with a bolt hole and fixed to the hydraulic device  50  by a bolt inserted in the bolt hole without using the pressing member  20 . 
     Further, in the above embodiment, at least two of the pipe body  210 ,  210 X, the pipe side combining portion  220 ,  220 X, and the flange portion  230  may be integrally formed instead of the configuration formed by joining separate parts. The pipe side combining portion  220 ,  220 X may have an uniform outer diameter over the entire length or may have a uniform thickness over the entire length. 
     The material for forming the hydraulic adapter unit  10 , the mouthpiece  100 , or the pipe member  200  in the above embodiment is merely an example and can be variously modified. 
     The method for manufacturing the pipe side combining portion  220 X in the above embodiment is merely an example and can be variously modified. For example, in step  120 , the pipe body  210 X and the pipe side combining portion  220 X may be joined by a brazing material other than silver braze, or may be joined by a method other than brazing, such as friction bonding. 
     REFERENCE SIGNS LIST 
       10 : hydraulic adapter unit,  10   a : hydraulic adapter unit,  20 : pressing member,  28 : bolt hole,  30 : bolt,  50 : hydraulic device,  51 : introduction hole,  52 : wall surface,  54 : screw hole,  56 : projecting portion,  60 : hose,  100 : mouthpiece,  100   a : mouthpiece portion,  102 : mouthpiece through-hole,  110 : hose fixing portion,  112 : inner cylindrical portion,  114 : outer cylindrical portion,  116 : groove,  120 : mouthpiece side combining portion,  122 : male screw portion,  130 : intermediate portion,  150 : O-ring,  200 ,  200   x : pipe member,  200 P: assembly,  210 ,  210   a ,  210 X: pipe body,  212 : pipe through-hole,  214 ,  214   a : bent portion,  216 ,  218 : straight portion,  220 ,  220 X: pipe side combining portion,  222 ,  222 X: nut through-hole,  224 : female screw portion,  225 : thick-walled portion,  226 : thin-walled portion,  227 : tapered portion,  230 ,  230   a  flange portion,  232 : facing surface,  234 : recessed portion,  236 : opposite surface,  238 : side surface,  300 : table,  310 : brazing material,  330 : heating unit,  332 : first coil,  334 : second coil,  336 : third coil