JP7695151B2 - Pipe fitting and its installation method - Google Patents

Description

The present invention relates to a pipe joint and its installation method.

The pipe fitting comprises a female member (adapter) and a male member (body) that are connected to each other via an elastic ring member that can expand and contract in diameter. This type of pipe fitting is used in automobiles, including commercial vehicles (trucks, buses, etc.), construction machinery, machine tools, etc., to easily connect one pipe to another pipe with a single touch, and various proposals have been made regarding such pipe fittings (see, for example, Patent Documents 1 and 2, etc.).

Patent Document 1 discloses a pipe joint in which the female and male members of the pipe joint are connected via an elastic ring member, and the connection between the female and male members is unlikely to be inadvertently released even when high-pressure fluid acts on them.

Patent Document 2 also discloses a pipe joint in which the female and male members cannot be separated once they are connected. Specifically, when fluid pressure is applied, the increase in pressure applies a force to the male member in the opposite direction to the insertion direction (the direction in which the male member is removed), but this pipe joint is configured so that the female and male members cannot be separated by inserting an elastic ring member into a groove in the female member.

Here, an example of a conventional pipe joint is shown in Figure 16 and Figures 17A to 17C. Figure 16 is a vertical cross-sectional view cut in half of a conventional pipe joint, and Figures 17A to 17C are enlarged detailed views of part D in Figure 16, showing the change in behavior of the elastic ring member when fluid pressure acts on the conventional pipe joint shown in Figure 16.

The illustrated pipe joint 101 comprises a female member 102 and a male member 103 which are connected to each other. A first locking groove 105 having a rectangular cross section is formed on the inner peripheral surface of the female member 102 all around, and a partially cut-out elastic ring member 107 which can be expanded or contracted is held in the first locking groove 105. On the other hand, a second locking groove 115 is formed on the outer peripheral surface of the male member 103. When the male member 103 is inserted into the female member 102 from above, for example, the elastic ring member 107 held in the first locking groove 105 of the female member 102 is pushed open by the male member 103, allowing the male member 103 to be inserted into the female member 102.

As shown in FIG. 17A, when the second locking groove 115 of the male member 103 matches the first locking groove 105 of the female member 102, the elastic ring member 107, which had been enlarged as shown by the dashed line in FIG. 17A, contracts as shown by the solid line due to its own elastic restoring force and fits into and locks into the second locking groove 115 of the male member 103, so that the female member 102 and the male member 103 are connected to each other via the elastic ring member 107. Therefore, even if fluid pressure acts on the pipe joint 101, the male member 103 is prevented from coming off the female member 102.

Japanese Utility Model Application Publication No. 5-054891 JP 2008-180366 A

However, when the conventional pipe fitting 101 shown in Fig. 16 is subjected to fluid pressure, and relative rotation between the female member 102 and the male member 103 is repeated due to, for example, vibration, the contact portion between the corner of the elastic ring member 107 and the second locking groove 115 of the male member 103 is scraped off to form a tapered surface, as shown in Fig. 17B, and the two come into surface contact via this tapered surface. At this time, when an upward force in the figure (a force in the direction in which the male member 103 is pulled out) acts on the male member 103 due to fluid pressure, a force _f1 acts in the direction perpendicular to the contact surface between the elastic ring member 107 and the second locking groove 115, as shown in Fig. 17B, and the horizontal component _f11 of this force _f1 causes the elastic ring member 107 to expand in diameter (expand in the direction of the arrow in the figure). This causes a problem that the engagement between the elastic ring member 107 and the second engagement groove 115 of the male member 103 is released, causing the male member 103 to slip out upward in the figure, as shown in FIG. 17C.

The present invention was made in consideration of the above problems, and its purpose is to provide a highly durable pipe fitting and a method for attaching the pipe fitting that can prevent the male member from coming off the female member even if relative rotation between the female member and the male member is repeated due to vibration or the like while fluid pressure is acting.

In order to achieve the above object, the pipe fitting according to the present invention comprises a cylindrical female member holding an elastic ring member that can be expanded or contracted in a first engagement groove formed on the inner circumferential surface, and a cylindrical male member having a second engagement groove formed on the outer circumferential surface, which is inserted while pushing the elastic ring member apart, and which connects to the female member via the elastic ring member, the elastic ring member being configured as a circular ring with a rectangular cross section with a portion cut out, and a first tapered surface that reduces in diameter toward the opening of the female member is provided on the opening side of the first engagement groove of the female member. The method of mounting the pipe fitting according to the present invention is characterized in that the female member is attached to the device, and then the male member is connected to the female member.

According to the present invention, the male member is inserted into the female member and the elastic ring member is engaged with both the first engagement groove of the female member and the second engagement groove of the male member, thereby connecting the female member and the male member to each other, and when fluid pressure acts on the pipe joint, the corner of the elastic ring member engages with the first tapered surface of the first engagement groove. The elastic ring member is contracted in diameter by the horizontal component of the force (force perpendicular to the first tapered surface) acting on the engagement portion of the corner of the elastic ring member with the first tapered surface, and the inner surface of the elastic ring member is pressed against the second engagement groove of the male member. As a result of the above, relative rotation between the female member and the male member due to vibration or the like is unlikely to occur when fluid pressure is acting, and even if rotation is repeated, the male member is prevented from coming off the female member.

FIG. 2 is a vertical cross-sectional view cut in half showing a state before fastening between a female member and a male member that constitute a pipe joint according to the first embodiment. FIG. 2 is an enlarged detailed view of part A in FIG. FIG. 2 is an enlarged detailed view of part B in FIG. FIG. FIG. 4 is a vertical cross-sectional view cut in half of the pipe joint, showing the state in which the male member is inserted into the female member. 6 is an enlarged detailed view of part C in FIG. 5 , illustrating a procedure for fastening the pipe joint. FIG. 6B is a diagram showing a process following FIG. 6A. FIG. 6C is a diagram showing a process following FIG. 6B. FIG. 4 is a vertical cross-sectional view cut in half of the pipe joint, showing a state in which the male member is fastened to the female member. 5 is an enlarged cross-sectional view of a main portion showing a change in behavior of an elastic ring member when fluid pressure acts on the pipe joint according to the embodiment. FIG. 8B is a diagram showing a change in behavior of the elastic ring member subsequent to FIG. 8A. 8C is a diagram showing a change in behavior of the elastic ring member subsequent to FIG. 8B. 8D is a diagram showing a change in behavior of the elastic ring member subsequent to FIG. 8C. FIG. 11 is a half-sectional front view showing another embodiment of the elastic ring member. FIG. 11 is a half cross-sectional front view showing still another embodiment of the elastic ring member. FIG. 11 is a half cross-sectional front view showing still another embodiment of the elastic ring member. FIG. 11 is a half cross-sectional front view showing still another embodiment of the elastic ring member. FIG. 11 is a half cross-sectional front view showing still another embodiment of the elastic ring member. FIG. 11 is a half cross-sectional front view showing still another embodiment of the elastic ring member. 10 is a cross-sectional view of a main portion showing a change in behavior of an elastic ring member when fluid pressure acts on a pipe joint of a second embodiment. FIG. 10B is a diagram showing a change in behavior of the elastic ring member subsequent to FIG. 10A. FIG. 11 is a vertical cross-sectional view cut in half showing a state before fastening of a female member and a male member of a pipe joint according to a first modified example of the present invention. FIG. 11 is a vertical cross-sectional view cut in half of a female member of a pipe joint according to a second modified example of the present invention. FIG. 11 is a vertical cross-sectional view cut in half of a female member of a pipe fitting according to a modified example 3 of the present invention. FIG. 11 is a vertical cross-sectional view cut in half of a female member of a pipe joint according to a fourth modified example of the present invention. FIG. 11 is a vertical cross-sectional view cut in half of a female member of a pipe fitting according to a modified example 5 of the present invention. FIG. 11 is a vertical cross-sectional view cut in half of a conventional pipe joint. 17 is an enlarged detailed view of portion D in FIG. 16 , showing a change in behavior of the elastic ring member when fluid pressure acts on the conventional pipe joint. FIG. 17B is a diagram showing a change in behavior of the elastic ring member subsequent to FIG. 17A. 17B shows the change in behavior of the elastic ring member. FIG.

An embodiment of the present invention will be described below with reference to the attached drawings.

First Embodiment
FIG. 1 is a vertical sectional view cut in half showing a state before fastening between a female member and a male member which constitute a pipe joint according to this embodiment, FIG. 2 is an enlarged detailed view of part A in FIG. 1, FIG. 3 is an enlarged detailed view of part B in FIG. 1, and FIG. 4 is a plan view of an elastic ring member.

As shown in FIG. 1, the pipe fitting 1 of this embodiment includes an adapter 2, which is a female member made of metal, and a body 3, which is a male member made of resin. For example, the adapter 2 is connected to a device, and the body 3 is connected to a brake pipe.

In this embodiment, the adapter 2 is made of a lead-containing copper-zinc alloy (C3604), and the body 3 is made of polyamide 12 (PA12) reinforced with glass fiber (GF), but these materials are merely examples and are not limiting. The material constituting the adapter 2 may be metal or resin. Metals that can be used include brass materials, lead-free materials such as C6801, aluminum alloys, steel materials, and stainless steel materials. Materials that can be used to constitute the body 3 include PPA reinforced with GF, but not only resin, but also brass forgings (C3771), lead-free brass materials, aluminum alloys, stainless steel alloys, etc. can be used.

The adapter 2 is a cylindrical member, and a flow path 4 formed by large and small circular holes 2a and 2b of different diameters is provided through the center of the shaft. In this embodiment, the configuration of the large and small circular holes 2a and 2b is shown, but this is just one example, and the circular holes may be the same diameter. A nut portion 2A is integrally formed on the outer periphery of the adapter 2 at the middle height position in the vertical direction in FIG. 1, and a threaded portion 2B is engraved on the outer periphery of the lower end portion below the nut portion 2A. The adapter 2 can be attached to the equipment by turning the nut portion 2A with a tool such as a spanner or wrench (not shown) to screw the threaded portion 2B into a threaded hole of the equipment (not shown). The shape of the threaded portion of the adapter 2 is just one example and is not limited. It may be a tapered thread, a parallel thread and a seal material, a metal seal, or the like. It may also be a female thread. In this embodiment, a configuration having a nut portion 2A is shown, but this is just one example, and it may be a configuration having an internal hexagon on the inside of the thread of the adapter 2, so that it can be attached to the equipment using a hexagonal wrench. In this case, the outside may be cylindrical rather than having the shape of the nut portion 2A.

A first locking groove 5 and a ring groove 6, each with a rectangular cross section, are formed around the entire circumference of the inner peripheral surface of the large-diameter circular hole 2a of the adapter 2. A resin elastic ring member, C-ring 7, is fitted and held in the first locking groove 5, and a ring-shaped O-ring 8, a sealing member, is fitted into the ring groove 6. The O-ring 8 can be made of a material such as ethylene propylene diene rubber (EPDM), acrylonitrile butadiene rubber (NBR), or hydrogenated nitrile rubber (HNBR). The C-ring 7 is not limited to resin and may be made of metal.

Here, the first locking groove 5 is formed all around the upper part (the upper end opening side of the adapter 2) in the height direction of the inner peripheral surface of the large diameter side circular hole 2a of the adapter 2. As shown in detail in FIG. 2, a first tapered surface 5a that reduces in diameter toward the opening direction of the adapter 2 is provided on the opening side of the adapter 2 of the first locking groove 5. Furthermore, a small inner diameter portion 5b having an inner diameter smaller than that of the first locking groove 5 is connected to the first tapered surface 5a and provided on the opposite side of the opening direction of the adapter 2. The small inner diameter portion 5b has a surface (vertical surface) parallel to the axial direction of the adapter 2 (the up-down direction in FIG. 2). Furthermore, a second tapered surface 5c that reduces in diameter toward the opening direction of the adapter 2 is connected to the small inner diameter portion 5b and provided on the opposite side of the opening direction of the adapter 2. In this way, the upper end opening side portion of the adapter 2 is formed with a first tapered surface 5a and a second tapered surface 5c in two stages that decrease in diameter toward the top in FIG. 2, and the inner peripheral surface connecting the first tapered surface 5a and the second tapered surface 5c constitutes the small inner diameter portion 5b. The bottom surface 5d at the lower end of the first engagement groove 5 in FIG. 2 is a ring-shaped flat surface (horizontal surface) parallel to the axis perpendicular direction of the adapter 2 (left and right direction in FIG. 2). The bottom surface 5d and the second tapered surface 5c are connected to each other by a vertical surface 5e that is parallel to the axial direction of the adapter 2.

As shown in FIG. 4, a resin C-ring 7 with a part of its outer circumference cut out is fitted and held in the first locking groove 5 formed in the adapter 2. Here, the C-ring 7 is a circular ring with a rectangular vertical section, and when the body 3 is not connected to the adapter 2 (when the C-ring 7 is in its initial state (unloaded state)), as shown in FIG. 2, its inner circumferential surface protrudes by ε as shown in the figure from the inner circumferential surface of the large-diameter circular hole 2a of the adapter 2, and a gap δ as shown is formed between the outer circumferential surface of the C-ring 7 and the vertical surface 5e of the first locking groove 5. In this embodiment, the C-ring 7 is made of polyamide 12 (PA12) reinforced with glass fiber (GF), which is the same material as the body 3, but is not limited to this.

As shown in FIG. 1, the body 3 is a cylindrical member that is bent in a horizontal L-shape, and includes a vertical portion 3A and a horizontal portion 3B that is bent at a right angle from the upper end of the vertical portion 3A and extends horizontally as one unit. A seal ring 9, a buckling ring 10, a lock ring 11, a lock ring holder 12, and a release ring 13 are provided at the open end of the horizontal portion 3B. A flow path 14 that is bent in a horizontal L-shape is also provided inside the body 3 through circular holes 3a and 3b of different diameters. In this embodiment, the body 3 is constructed from a member that is bent in a horizontal L-shape, but the body 3 may also be constructed from a T-shaped or Y-shaped member.

Furthermore, a flange portion 3C is integrally formed at the mid-height position of the outer periphery of the vertical portion 3A of the body 3, and the portion below this flange portion 3C constitutes the insertion portion 3A1 to be inserted inside the adapter 2. A tapered surface 3c that narrows downward is formed on the outer periphery of the lower end of this insertion portion 3A1. Here, a second locking groove 15 is formed around the entire circumference of the outer periphery of the insertion portion 3A1. As shown in detail in FIG. 3, a tapered surface 15a that widens upward is formed at the upper end of this second locking groove 15, and the bottom surface 15b of the lower end, which is the end surface of the second locking groove 15 on the opening side of the body 3, is a plane (horizontal plane) perpendicular to the vertical axis of the insertion portion 3A1 of the body 3. The tapered surface 15a and the bottom surface 15b of the lower end of this second locking groove 15 are connected to each other by a vertical surface 15c.

Next, the procedure for connecting the adapter 2 and the body 3 of the pipe fitting 1 configured as described above will be explained below with reference to Figures 5 to 7.

Figure 5 is a vertical cross-sectional view of the pipe fitting 1 showing the state in which the body 3 is inserted into the adapter 2, Figures 6A to 6C are enlarged detailed views of part C in Figure 5 showing the process steps for fastening the pipe fitting, and Figure 7 is a vertical cross-sectional view of the pipe fitting 1 showing the state in which the body 3 has been fastened to the adapter 2.

The pipe fitting 1 of this embodiment can be used for air piping, such as air brake piping for vehicles such as trucks. The pipe fitting 1 of this embodiment can be installed without interfering with other pipe fittings 1 even at narrow pitches by first attaching the adapter 2 to the equipment using a tool such as a torque driver.

As shown in FIG. 5, the pipe fitting 1 of this embodiment is used by inserting the insertion portion 3A1 of the body 3 from above into the inside of the adapter 2 that is fixed vertically to the pipe fitting 1.

As described above, when the insertion portion 3A1 of the body 3 is inserted from above into the inside of the adapter 2, as shown in Figure 6A, the tapered surface 3c formed on the outer peripheral edge of the lower end of the insertion portion 3A1 of the body 3 comes into contact with the inner peripheral edge of the upper end of the C-ring 7 that is fitted and held in the first locking groove 5 of the adapter 2, pushing the C-ring 7 in the direction of the arrow in the figure, expanding the diameter of the C-ring 7. Then, as shown in Figure 6B, the C-ring 7 sinks into the first locking groove 5, allowing the body 3 to pass (be pushed in).

As shown in Figure 6C, when the second locking groove 15 of the body 3 matches the first locking groove 5 of the adapter 2, the force expanding the diameter of the C-ring 7 is released, and the C-ring 7 contracts in diameter due to its own elastic restoring force, returning to its original initial state and being locked in the second locking groove 15 of the body 3. As a result, as shown in Figure 7, the body 3 is connected to the adapter 2 via the C-ring 7 by the simple operation of simply inserting the body 3 into the adapter 2 from above. Therefore, for example, in the limited space inside the bonnet of a truck, the pipe fittings 1 can be attached with good workability while preventing interference between multiple pipe fittings 1.

Next, the behavior of the C-ring 7 when fluid pressure acts on the pipe fitting 1 in which the adapter 2 and the body 3 are fastened by the above procedure will be explained below with reference to Figures 8A to 8D.

8A to 8D are enlarged cross-sectional views of the main part showing the behavior of the C-ring 7 when fluid pressure acts on the pipe joint 1 according to this embodiment. When no fluid pressure acts on the pipe joint 1, the C-ring 7 is in the state shown in FIG. 6C. However, when fluid pressure acts on the pipe joint 1, that is, when high-pressure air flows through the flow passage 4 of the adapter 2 and the flow passage 14 of the body 3, the body 3 receives a force in the direction of coming out of the adapter 2 (upward in FIG. 8A to FIG. 8D). Then, as shown in FIG. 8A, the body 3 moves upward until the corner of the upper end outer circumferential edge of the C-ring 7 engages with the second tapered surface 5c of the first engagement groove 5 at the engagement point p. At this engagement point p of the C-ring 7 with the second tapered surface 5c of the first engagement groove 5, the C-ring 7 is reduced in diameter by the horizontal component force _F11 of the force _F1 acting on the C-ring 7 (the force perpendicular to the second tapered surface 5c).

Furthermore, the bottom surface 7b of the C ring 7 comes into surface contact with the bottom surface 15b of the second locking groove 15 of the body 3, and an upward normal force N acts on this contact surface. At this time, if the friction coefficient of the contact surface is μ, then a frictional force of μ·N acts on the bottom surface 7b of the C ring 7. This frictional force μ·N and the horizontal component _F11 of the force _F1 acting on the engagement point p are equal in magnitude and act in opposite directions to each other, so that a couple M (see FIG. 8B) in the direction of the arrow (clockwise) acts on the C ring 7, and when the corner of this C ring 7 reaches the end of the second tapered surface 5c of the first locking groove 5 as shown in FIG. 8B, the C ring 7 is tilted by the couple M.

When the engagement point p of the corner of the C-ring 7 is disengaged from the second tapered surface 5c of the first locking groove 5, as shown in FIG. 8C, the upper end of the C-ring 7 enters the space S formed between the small inner diameter portion 5b of the first locking groove 5 and the vertical surface 15c of the second locking groove 15, and the corner engages with the first tapered surface 5a of the first locking groove 5 at the engagement point q. At this time, the width w of the space S formed between the small inner diameter portion 5b of the first locking groove 5 and the vertical surface 15c of the second locking groove 15 becomes larger than the thickness t of the C-ring 7 (w>t), and the upper end of the C-ring 7 enters the space S. Therefore, the inclination of the C-ring 7 is restricted and kept small by the small inner diameter portion 5b of the first locking groove 5.

In the above state, the C ring 7 and the body 3 can move upward (in the direction in which the body 3 comes off) until the corner of the C ring 7 engages with the first tapered surface 5a of the first locking groove 5 at the engagement point q as shown in Fig. 8C, and further movement, i.e., the body 3 is prevented from coming off from the adapter 2. At this time, a force _F2 perpendicular to the first tapered surface 5a acts on the engagement point q of the corner of the C ring 7 with the first tapered surface 5a, and the C ring 7 is contracted in diameter by a horizontal component _F21 of this force _F2 , and its inner peripheral surface is pressed against the vertical surface 15c of the second locking groove 15 of the body 3. Therefore, the engagement allowance (hanging allowance) ε2 of the C ring 7 with the bottom surface 15b of the second locking groove 15 becomes larger than the engagement allowance ε1 shown in Fig. 8A (ε2>ε1), and the body 3 is further prevented from coming off from the adapter 2. Therefore, even if relative rotation between the adapter 2 and the body 3 is repeated due to vibration or the like while fluid pressure such as air pressure is acting, the body 3 is prevented from coming off the adapter 2, and the durability of the pipe fitting 1 against rotation is increased.

8D, even if the corners of the C-ring 7 are scraped off by rubbing against the second tapered surface 5c of the first locking groove 5 to form a tapered surface 7a, the C-ring 7 is pressed in the diameter-reducing direction by a horizontal component force _F31 of a force F3 perpendicular to the first tapered surface _5a of the first locking groove 5. As a result, the inner peripheral surface of the C-ring 7 is pressed against the vertical surface 15c of the second locking groove 15, so that an engagement allowance (hanging allowance) ε3 of the C-ring 7 with the second locking groove 15 is sufficiently secured, and the body 3 is prevented from coming off the adapter 2 even when fluid pressure is acting on the pipe fitting 1.

Here, different forms of the C-ring 7 are shown in Figures 9A to 9F. As shown in Figure 9A, the corners of the outer peripheral edge of the upper end (one axial end) of the C-ring 7 may be cut diagonally to form a tapered surface 7c. In this case, there is a possibility that the C-ring 7 may be misassembled by turning it upside down when assembling the pipe fitting 1, so as shown in Figure 9B, both corners of the outer peripheral edge of the upper and lower parts (both axial ends) of the C-ring 7 may be cut diagonally to form each of these parts into a tapered surface 7c. In addition, as shown in Figure 9C, a tapered surface 7c may be formed at the corners of the upper inner peripheral edge of the C-ring 7, and as shown in Figure 9D, a tapered surface 7c may be formed at each corner of the upper inner and outer peripheral edges of the C-ring 7. Alternatively, as shown in FIG. 9E, tapered surfaces 7c may be formed on each corner of the upper inner peripheral edge and the lower outer peripheral edge of the C-ring 7, and as shown in FIG. 9F, tapered surfaces 7c may be formed on each corner of the upper inner peripheral edge and the lower outer peripheral edge of the C-ring 7, excluding the lower inner peripheral edge.

According to the pipe fitting 1 of this embodiment, the horizontal components F21, F31 of the forces _F2 , _F3 (forces perpendicular to the first tapered surface 5a) acting on the engaging portion of the corner of the C ring 7 with the first tapered surface _5a cause the C ring 7 to contract in diameter, and the inner peripheral surface of the C ring 7 is pressed against the second locking groove 15 of the body 3. As a result of the above, even if relative rotation _between the adapter 2 and the body 3 is repeated due to vibration or the like while fluid pressure is acting, the body 3 is prevented from coming off the adapter 2, and the durability of the pipe fitting 1 against rotation is improved.

In addition, with the pipe fitting 1 of this embodiment, the frictional force at the contact surface between the C-ring 7 and the body 3 is reduced, which reduces the amount of wear at the contact surface between the C-ring 7 and the body 3, preventing the body 3 from coming off the adapter 2.

Second Embodiment
In the pipe joint of this embodiment, the configuration of the first locking groove 205 differs from that of the first embodiment as described below, but apart from this point, the configuration is similar to that of the first embodiment.

Figures 10A and 10B are enlarged cross-sectional views of the main parts showing the behavior of the C-ring when fluid pressure acts on the pipe joint according to this embodiment.

As shown in FIG. 10A, the first engagement groove 205 has a first tapered surface 205a on the opening side of the adapter 202, the first tapered surface 205a narrowing in diameter toward the opening of the adapter 202. The bottom surface 205d at the lower end of the first engagement groove 205 in FIG. 10A is a ring-shaped flat surface (horizontal surface) parallel to the axis perpendicular to the adapter 202 (left-right direction in FIG. 10A). The bottom surface 205d and the first tapered surface 205a are connected to each other by a vertical surface 205e parallel to the axial direction of the adapter 202.

In a pipe fitting having the above-described locking structure, as shown in FIG. 10A, when the adapter 202 and the body 203 are connected, the C-ring 207 is locked in both the first locking groove 205 of the adapter 202 and the second locking groove 215 of the body 203, preventing the body 203 from coming off the adapter 202.

When fluid pressure acts on the pipe joint and the body 203 receives a force in a direction to come out of the adapter 202 (upward in Fig. 10A), as shown in Fig. 10B, the corner of the C-ring 207 comes into contact with the tapered surface 205a of the first locking groove 205 formed in the adapter 202 at engagement point a, and also comes into contact with the second locking groove 215 formed in the body 203 at engagement point b. At this time, a force _f2 perpendicular to the tapered surface 205a of the first locking groove 205 acts on the engagement point a.

According to the pipe joint of this embodiment, the horizontal component force _f21 of the force (force perpendicular to the tapered surface 205a) _f2 acting on the engagement portion between the corner of the C-ring 207 and the tapered surface 205a causes the C-ring 207 to contract in diameter, and the inner peripheral surface of the C-ring 207 is pressed against the second locking groove 215 of the body 203. As a result of the above, even if relative rotation between the adapter 202 and the body 203 is repeated due to vibration or the like while fluid pressure is acting, the body 203 is prevented from coming off the adapter 202, and the durability of the pipe joint against rotation is increased.

An upward normal force N acts on the engagement point b between the corner of the C-ring 207 and the bottom surface 215b of the second locking groove 215, and if the friction coefficient at the engagement point b is μ, then a frictional force μ·N in the direction of the arrow in the figure acts on this engagement point b. Therefore, a couple of forces in the clockwise direction in Fig. 10B acts on the C-ring 207 due to the horizontal component force _f21 of the force _f2 and the frictional force μ·N, and this couple of forces may cause the C-ring 207 to fall inside the first locking groove 205 and the second locking groove 215, and the engagement allowance (hanging allowance) of the C-ring 207 with the second locking groove 215 at the engagement point b may become smaller. In this case, as shown in the first embodiment, a small inner diameter portion is provided in the first locking groove 205, and the C-ring 207 is configured to enter the space between the first locking groove 205 and the second locking groove 215, so that the collapse of the C-ring 207 can be restricted and kept small by the small inner diameter portion of the first locking groove 205.

The present invention is not limited to the application of the embodiments described above, and various modifications are possible within the scope of the technical ideas described in the claims and the specification and drawings. For example, the second tapered surface may be a surface parallel to the axis perpendicular to the adapter, i.e., a surface parallel to the bottom surface of the lower end of the first engagement groove. Also, contrary to the above embodiments, the adapter may be a male member and the body a female member. Furthermore, the pipe fitting may have multiple female members and multiple male members.

Here, various modified examples of the pipe joint according to the present invention will be described below with reference to Figures 11 to 15.

<Modification 1>
Fig. 11 is a half-cut vertical cross-sectional view showing the female and male members of a pipe fitting according to a first modified example of the present invention before fastening, and in the pipe fitting 1A according to this modified example, the female and male members are reversed compared to the pipe fitting 1 according to the first embodiment (see Fig. 1). That is, the body 3, which is the male member located below the adapter 2, which is the female member located at the top of Fig. 11, is inserted into the adapter 2, which is the female member located at the top of the pipe fitting, and the adapter 2 and the body 3 are easily connected with a single touch. In reality, the body 3 is fastened to an unillustrated device using a tool not shown, and then the body 3 is inserted into the adapter 2 from below to connect the two.

In FIG. 11, the same elements as those shown in FIG. 1 are given the same reference numerals, and in the adapter 2, a C-ring 7 is fitted and held in the first locking groove 5, and an O-ring 8 is fitted in the ring groove 6. In addition, in the body 3, a second locking groove 15 is formed on the outer periphery of the insertion portion 3A1.

The basic configuration of the pipe fitting 1A of this modified example, configured as described above, is the same as that of the pipe fitting 1 of the first embodiment (see FIG. 1), so the pipe fitting 1A of this modified example also provides the same effects as those obtained in the first embodiment.

<Modification 2>
Fig. 12 is a vertical cross-sectional view cut in half of the female member of a pipe joint according to Modification 2 of the present invention, in which an O-ring 17 for preventing foreign matter is fitted in a ring groove 16 formed around the entire circumference of the inner periphery of the upper end of the female member, the adapter 2, and the other configuration is the same as that of the adapter 2 according to the first embodiment (see Fig. 1). Therefore, in Fig. 12, the same elements as those shown in Fig. 1 are given the same reference numerals.

<Modification 3>
Fig. 13 is a vertical cross-sectional view of the female member of the pipe joint according to the third modified example of the present invention. In this modified example, a circular hole 2c of the same diameter is provided through the axial center of the adapter 2, which is the female member, and a C-ring 7 and an O-ring 8 are fitted and held in the first locking groove 5 and ring groove 6 formed above and below this circular hole 2c, respectively. In addition, an O-ring 18 is fitted on the outer periphery between the nut portion 2A and the threaded portion 2B in the height direction (vertical direction). The other configurations are the same as those of the adapter 2 according to the first embodiment (see Fig. 1). Therefore, in Fig. 13, the same elements as those shown in Fig. 1 are given the same reference numerals.

<Modification 4>
FIG. 14 is a half-cut vertical cross-sectional view of the female member of a pipe fitting according to a fourth modified example of the present invention. In this modified example, an O-ring 17 for preventing foreign matter is fitted in a ring groove 16 formed at the upper end of the circular hole 2c in the adapter 2 according to the third modified example, and the other configuration is the same as that shown in the third modified example (see FIG. 13).

<Modification 5>
15 is a vertical cross-sectional view cut in half of the female member of a pipe joint according to the fifth modified example of the present invention, in which the adapter 2 is configured as a T-shaped tubular member, and three openings (two at the top and bottom and one at the side) are formed in the adapter 2. A C-ring 7 and an O-ring 8 are respectively fitted in each of the three openings.

Therefore, elbow-shaped or Y-shaped bodies (not shown) can be inserted and connected to this adapter 2 from three directions.

<How to install pipe fittings>
The pipe joints of the above-described embodiments and modified examples are attached, for example, by attaching the adapter 2 to a device and then connecting the body 3 to the adapter 2 .

1 Pipe joint 2 Adapter (female member)
3 Body (male member)
5 First locking groove 5a First tapered surface of first locking groove 5b Small inner diameter portion of first locking groove 5c Second tapered surface of first locking groove 5d Bottom surface of first locking groove 5e Vertical surface of first locking groove 7 C-ring 7a Tapered surface of C-ring 7b Bottom surface of C-ring 7c Tapered surface of C-ring 15 Second locking groove 15a Tapered surface of second locking groove 15b Bottom surface of second locking groove 15c Vertical surface of second locking groove

Claims (5)

a cylindrical female member having an elastic ring member that can be expanded or contracted in a first engagement groove formed on an inner circumferential surface of the female member;
a male member having a cylindrical shape with a second locking groove formed on an outer circumferential surface thereof, the male member being coupled to the female member via the elastic ring member by being inserted into the male member while pushing the elastic ring member apart,
The elastic ring member is formed of a circular ring having a rectangular longitudinal section with a portion cut out,
a first tapered surface having a diameter decreasing toward the opening direction of the female member is provided on a portion of the first engagement groove on the opening side of the female member ,
a small inner diameter portion having an inner diameter smaller than that of the first engagement groove is connected to the first tapered surface and is provided on the opposite side in the opening direction of the female member,
a second tapered surface, the second tapered surface being tapered in diameter toward the opening direction of the female member, is connected to the small inner diameter portion and is provided on the opposite side of the opening direction of the female member;
an end surface of the first engagement groove opposite to an opening direction of the female member is formed as a flat surface perpendicular to an axial direction of the female member,
The end surface of the first engagement groove and the second tapered surface are connected to each other by a surface parallel to the axial direction of the female member,
In the female member, the elastic ring member is held in the first engagement groove such that a corner of an outer peripheral edge portion at one axial end of the elastic ring member and the second tapered surface face each other in the axial direction of the female member,
When the male member and the female member are fastened together and the elastic ring member is engaged in both the first engagement groove and the second engagement groove, a fluid pressure acts on the male member to apply a force in a direction in which the male member is removed from the female member, and the corners of the elastic ring member facing each other and the second tapered surface are engaged with each other, and the elastic ring member is reduced in diameter by a horizontal component of a force perpendicular to the second tapered surface that acts on the engagement point between the corners of the elastic ring member and the second tapered surface,
When the corner portion of the elastic ring member comes off the second tapered surface due to the diameter reduction of the elastic ring member, the corner portion of the elastic ring member enters into a space formed between the small inner diameter portion and the second engagement groove, thereby engaging the corner portion of the elastic ring member with the first tapered surface, and the diameter of the elastic ring member is reduced by a horizontal component of a force perpendicular to the first tapered surface that acts on an engagement point between the corner portion of the elastic ring member and the first tapered surface, and the inner peripheral surface of the elastic ring member is pressed against the second engagement groove.
Pipe fittings. 2. The pipe fitting according to claim 1 , wherein the reduced inner diameter portion has a surface parallel to an axial direction of the female member. 3. The pipe joint according to claim 1, wherein an end face of the second locking groove on the opening side of the male member is formed as a flat surface perpendicular to an axial direction of an insertion portion of the male member into the female member. 4. The pipe joint according to claim 1 , wherein a tapered surface is provided on an outer circumferential edge portion at one axial end or at both axial ends of the elastic ring member. A method for mounting a pipe joint according to any one of claims 1 to 4 , comprising the steps of:
A method for attaching a pipe joint, comprising the steps of attaching the female member to an apparatus and then connecting the male member to the female member.

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