Pressure resistance pipe joint

Abstract

To provide a pressure-resistance pipe joint which does not use fire at the connection of a connected pipe body, does not need to use a dedicated tool, can maintain the insertion resistance of the connected pipe body low while securing excellent pressure resistance, and is suppressed in the number of components.SOLUTION: In a pipe joint 10 having: a joint main body 12 to which a copper pipe 22 is inserted and fixed; a regulation ring 14 including a plurality of lock claws 14b for preventing the withdrawal of the copper pipe 22; an O-ring 18 located axially outside an insertion hole 24 rather than the regulation ring 14 and sealing a clearance between the copper pipe 22 and the insertion hole 24; and a pressurization bush 20 screwed to the joint main body 12, and pressurizing and compressing the O-ring 18 by the progress of the screwing, a base part of the lock claw 14b is formed into a narrow width part 32 which becomes narrower in a width than a tip part which bites into an outer surface of the copper pipe 22, curved at the narrow width part 32, and inclined to an insertion direction front side of the copper pipe 22.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pressure-resistant pipe joint, and more particularly to a pressure-resistant pipe joint structure that can be suitably used for connecting pipes through which a fluid flows under high pressure, such as refrigerant pipes in air conditioning equipment. [Background technology]

[0002] Conventionally, various pipe fittings such as sockets, adapters, T-shaped, T-shaped, Y-shaped, cross-shaped, 90° elbows, etc. have been widely used to connect pipes that transport fluids such as liquids and gases to other pipes or to the desired equipment. For example, such pipe fittings have been used in connection work for water pipes, pipes for connecting hot water equipment, and refrigerant pipes in air conditioning equipment.

[0003] In the case of this type of pipe fitting, it has been common to use a brazing method to fasten the fitting to the pipe to be connected (connected pipe). However, because this requires the use of open flame during the work, it is difficult to employ this method for pipe connection work at piping sites such as above the ceiling. Therefore, various pipe fitting structures have been proposed that mechanically connect the connected pipe and the fitting without using open flame as in the conventional brazing method.

[0004] For example, in JP 2000-249268 A, as a joint structure that can be connected simply by inserting a connected pipe, when connecting a pipe and a joint body, a female thread formed on a pressing body is screwed into a male thread formed on the joint body, a lock ring or the like is sandwiched and fixed between the joint body and the pressing body, and a joint is proposed in which the pipe to be connected is inserted into the joint body through the pressing body, and the regulating piece of the lock ring is engaged with the outer peripheral surface of the pipe to prevent the pipe from being pulled out. In addition, JP 2019-90503 A also discloses a pipe joint structure in which a cap member is screwed into the opening of the joint body, and in a state in which a lock ring is sandwiched and fixed between the joint body and the cap member, the pipe to be connected is inserted into the joint body through the cap member, and the claws of the lock ring are allowed to bite into the outer peripheral surface of the pipe to restrict the insertion of the inserted pipe.

[0005] However, in pipe joint structures in which the connected pipe is inserted, in order to prevent leakage of the fluid flowing through the connected pipe, it is necessary to provide sealing means in at least two places, including a seal between the joint body and the pressing body or the cap member, and a seal between the connected pipe and the pressing body or the cap member.As a result, not only does the sealing structure in the pipe joint structure become complex, but there is also an inherent risk that the screwing of the pressing body or the cap member onto the joint body will loosen, causing leakage or causing the connected pipe to fall off.

[0006] In addition, JP 2003-42369 A discloses a one-touch joint structure in which an O-ring and a restricting ring are sequentially inserted and arranged in one opening of a cylindrical joint body, and a ring-shaped retaining member is further inserted, and the end of the opening of the joint body is crimped inward to crimp and fix the retaining member, and by inserting a pipe to be connected into the opening of the joint body, the tip of the restricting tongue of the restricting ring is made to bite into the outer circumferential surface of the pipe, preventing the pipe from coming off. However, since an O-ring sealing mechanism is disposed downstream in the pipe insertion direction, scratches are generated on the outer surface of the pipe that passes through the restricting ring when the pipe is inserted, and the O-ring seals the surface where the scratches occurred, so there is an inherent problem that the sealing characteristics cannot be fully exhibited.

[0007] Moreover, in the above-mentioned conventional insertion type coupling structure, the connected pipe is attached by simply inserting it into the insertion hole of the coupling body, and the resistance to the removal of the connected pipe is realized by the restricting piece or restricting tongue of the lock ring or restricting ring biting into the outer circumferential surface of the connected pipe, so there is an inherent problem that it is difficult to fully exert the pressure resistance and pull-out prevention force required for the connection in piping where a fluid flows under high pressure, such as refrigerant piping in an air conditioner. Furthermore, if the lock ring or restricting ring is installed in multiple stages or the restricting piece or restricting tongue of the lock ring or restricting ring is made hard or strong in order to increase the pull-out prevention force of the connected pipe, the insertion resistance of the connected pipe becomes excessive, resulting in a problem that it becomes difficult for an operator to insert it manually. In particular, the larger the diameter of the connected pipe, the greater the insertion resistance of the connected pipe. Specifically, when the diameter (outer diameter / nominal diameter) of the connected pipe is 22.22 mm or more, an insertion force that is greater than the strength of an average man is required. For example, to insert a connected pipe with a diameter of 28.58 mm, an insertion force of 0.6 kN or more is required, making it extremely difficult for an operator to insert the connected pipe with their bare hands.

[0008] For this reason, the applicant of the present application proposed a pressure-resistant pipe joint in JP 2022-29434 A that allows connection work to be performed using the normal force of an operator, even when the connected pipe has a large outer diameter. In this structure, a plurality of locking claws of a regulating ring arranged in a fixed position within an insertion hole of a joint body are pushed outward in the radial direction, a predetermined guide cylinder is arranged within the regulating ring, and when the target connected pipe is inserted, the end of the connected pipe is pressed against the guide cylinder to push it into the back of the insertion hole, so that the connected pipe is inserted into the regulating ring instead of the guide cylinder, and the connected pipe is fixed and held by the plurality of locking claws being dug into the outer surface of the connected pipe. This makes it possible for the operator to insert and place such a connected pipe into the regulating ring relatively easily, simply, and quickly.

[0009] However, in a pressure-resistant pipe joint using such an induction cylinder, it is necessary to prepare a special member called the induction cylinder, which increases the number of parts that make up the pipe joint, and therefore there is a problem that an increase in costs is unavoidable.In addition, it is necessary to insert the induction cylinder into the insertion hole of the joint body of the pipe joint in advance and to position the multiple locking claws of the regulating ring by pushing them outward in the radial direction, which also poses the problem of an increase in the number of work steps. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2000-249268 A [Patent Document 2] JP 2019-90503 A [Patent Document 3] JP 2003-42369 A [Patent Document 4] Patent Publication No. 2022-29434 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made against the background of the above circumstances, and its problem to be solved is to provide a pressure-resistant pipe fitting with a small number of parts that can connect a pipe to be connected without the use of fire or special tools, while ensuring excellent pressure resistance and maintaining low insertion resistance of the pipe to be connected. Another problem is to provide a pressure-resistant pipe fitting that allows a worker to connect a large-diameter pipe to be connected, such as one with an outer diameter of 19 mm or more, using normal force. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems or problems understood from the description of the entire specification and the drawings, the present invention can be preferably implemented in various aspects as listed below, and each aspect described below can be adopted in any combination. It should be understood that the aspects and technical features of the present invention are not limited to those described below, but can be recognized based on the technical contents disclosed in the description of the entire specification and the drawings.

[0013] Therefore, in order to solve the above-mentioned problems, the present invention first provides a cylindrical coupling body having an insertion hole at least on one end side, into which a connected pipe is inserted from its pipe end and fixed; a restriction ring disposed in a fixed position within the insertion hole, the restriction ring having a plurality of elastically deformable locking claws positioned at predetermined intervals in the circumferential direction of the insertion hole, which bite into the outer surface of the connected pipe inserted into the insertion hole to prevent the connected pipe from being pulled out; sealing means consisting of an O-ring disposed axially outward of the restriction ring and exposed within the insertion hole, the O-ring contacting the outer surface of the connected pipe inserted into the insertion hole to seal between the outer surface of the connected pipe and the inner surface of the insertion hole; and a sealing member screwed into the end of the coupling body on which the connected pipe is inserted, the O-ring being screwed into the circumferential direction of the insertion hole as the screwing progresses. The gist of this pressure-resistant pipe coupling is that it has a cylindrical pressure bushing having an axially formed insertion hole for the connected pipe to be inserted into the insertion hole, and the O-ring is pressurized and compressed in the axial direction to expand the O-ring radially inward, thereby improving the pressing ability against the outer surface of the connected pipe, wherein the regulating ring has a circular plate-shaped ring body of a predetermined width that is held in a fixed position within the insertion hole of the coupling body, and the multiple locking claws are arranged so as to extend integrally from the inner peripheral portion of the ring body toward the center of the ring body, and at least one of the multiple locking claws has a narrow portion at its base that is narrower than the width of the tip portion that bites into the outer surface of the connected pipe, and is bent at the narrow portion so as to be inclined forward in the insertion direction of the connected pipe.

[0014] According to one preferred embodiment of the pressure-resistant pipe fitting of the present invention, the regulating ring is clamped and fixed by a thread collar member which screws into a threaded portion provided on the inner surface of the insertion hole and abuts against a stepped portion formed on the inner surface of the insertion hole.

[0015] According to another preferable aspect of the pressure-resistant pipe joint of the present invention, the pressure bushing is attached by being screwed into a threaded portion provided on the inner peripheral portion of the end portion of the joint body on the insertion side of the connected pipe.

[0016] Furthermore, according to another desirable aspect of the pressure-resistant pipe joint of the present invention, the pressure bushing has a knurled outer surface, and the pressure bushing can be screwed in by hand by gripping the knurled portion.

[0017] In addition, the present invention is advantageously characterized in that a plurality of the O-rings are arranged in the axial direction of the insertion hole with annular spacers interposed between adjacent O-rings.

[0018] According to another preferable aspect of the pressure-resistant pipe fitting of the present invention, there is provided a stopper means which is provided on the inner surface of the insertion hole deeper than the position of the regulating ring, against which the connected pipe inserted into the insertion hole abuts, thereby preventing its movement.

[0019] Furthermore, according to still another preferable aspect of the pressure-resistant pipe joint of the present invention, the joint body has an insertion hole at each end, and the two connected pipes are connected by inserting and fixing the connected pipes into the insertion holes using the regulating ring, the sealing means and the pressure bushing.

[0020] Furthermore, in a preferred embodiment of the pressure resistant pipe joint according to the present invention, the connected pipe body is a large-diameter pipe body having an outer diameter of 19 mm or more. Effect of the Invention

[0021] In such a pressure-resistant pipe joint according to the present invention, the multiple locking claws of the regulating ring are arranged in a fixed position within the insertion hole of the joint body, and at least one of them has a narrow portion formed at its base which is narrower than the width of the tip and is bent at this narrow portion. Therefore, when a specific connected pipe is inserted, the locking claws having such a narrow portion are easily spread radially outward, thereby effectively reducing the insertion resistance of the connected pipe into the regulating ring. Thus, without using the guide cylinder previously proposed by the applicant of the present application, the work of fitting and arranging the connected pipe into the regulating ring can be relatively easily, simply and quickly performed by the operator, and thus the joint can be advantageously used as a so-called one-touch joint.

[0022] Moreover, the force preventing the connected pipe from being pulled out, which is based on the locking claws of the regulating ring, is exerted when the tip of the locking claw bites into the outer surface of the connected pipe. Therefore, even if the base of the locking claw is narrow, there is no change in the width of its tip. Therefore, there is almost no change in the pull-out resistance force exerted when such a tip bites into the outer surface of the connected pipe. Therefore, sufficient pull-out resistance force can be exerted. In addition, when the pressure bushing that is screwed onto the end of the coupling body is further screwed in, the O-ring that seals between the inner surface of the insertion hole of the coupling body and the outer surface of the connected pipe to be inserted is pressurized and compressed, causing it to bulge radially inwardly from the insertion hole. This effectively enhances the adhesion or crimping ability to the outer surface of the inserted connected pipe, and thereby makes it possible to realize a coupling structure with excellent pressure resistance.

[0023] Thus, with the pressure-resistant pipe fitting according to the present invention, no fire or special dedicated tools are used, and there is no need to spread the locking claws of the restricting ring on the guide cylinder. Instead, the connection between the connected pipe and the pipe fitting can be completed simply by inserting the desired connected pipe through the insertion hole in the pressure bush of the pipe fitting and into the insertion hole of the fitting body with low insertion resistance using only the bare hands of the operator. Since the number of parts can be reduced while still exhibiting excellent pressure resistance, it can be advantageously used for connecting connected pipes through which a high-pressure refrigerant or other fluid flows. It can also be advantageously used to connect not only pipes with small outer diameters, but also refrigerant pipes with large outer diameters of 19 mm or more, even as large as 38.1 mm. [Brief description of the drawings]

[0024] [Figure 1] 1 is a partial longitudinal sectional view showing an example of a pressure-resistant pipe joint according to the present invention; [Diagram 2] 2 is an explanatory vertical sectional view showing the entire joint body used in the pressure-resistant pipe joint shown in FIG. 1. [Diagram 3] 2A and 2B are explanatory diagrams showing a state before the locking claws of a restriction ring used in the pressure-resistant pipe joint shown in FIG. 1 are bent, in which (a) is an explanatory plan view thereof, (b) is an explanatory right side view thereof, and (c) is an enlarged explanatory view of part A in (a). [Figure 4] 3 is an explanatory diagram showing a shape of a restricting ring used in the pressure-resistant pipe joint shown in FIG. 1 in which the locking claws are bent as shown in FIG. 3, (a) being its planar explanatory view, (b) being a cross-sectional view taken along line BB in (a), and (c) being an enlarged explanatory view of the cross section of the locking claws at part C in (b). [Diagram 5] 2A and 2B are explanatory diagrams showing a thread collar used in the pressure-resistant pipe joint shown in FIG. 1, in which (a) is a front explanatory diagram, and (b) is a DD cross-sectional explanatory diagram in (a). [Figure 6]2A and 2B are explanatory diagrams showing a pressure bushing used in the pressure-resistant pipe joint shown in FIG. 1, in which (a) is an explanatory front view, and (b) is an explanatory E-E cross-sectional view of (a). [Figure 7] FIG. 2 is an explanatory longitudinal cross-sectional view showing the process of inserting and connecting a connected pipe body to the pressure-resistant pipe joint shown in FIG. 1, where (a) shows the state during the process of inserting the connected pipe body, and (b) shows the state after the connected pipe body has been inserted. [Figure 8] 2 is a longitudinal sectional view corresponding to FIG. 1 of a pressure-resistant pipe joint in which a pressure bush having a different structure is used. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In order to clarify the configuration of the present invention more specifically, representative embodiments of the present invention will be described in detail below with reference to the drawings.

[0026] First, in Fig. 1, a representative example of a pressure-resistant pipe joint according to the present invention is shown in a longitudinal cross-sectional form, here in its left half. In this, the pipe joint 10 is configured to include a joint body 12 having an overall cylindrical shape, a restricting ring 14, a thread collar 16, and two O-rings 18, 18 each arranged in the joint body 12, and a pressure bush 20 screwed into an end opening of the joint body 12. The other half of the joint body 12 (the part on the right side not shown in Fig. 1) also has a structure similar to that of the left side part shown in the figure. And, a copper pipe 22 made of a material such as copper or a copper alloy is inserted as a connected pipe body into such a pipe joint 10 to be connected.

[0027] Specifically, the joint body 12, which is one of the components constituting the pipe joint 10, is made of a metal pipe of a predetermined length with a small diameter portion at the axial center, as shown in Fig. 2, and the pipes (copper pipes 22 in this case) to be connected are inserted from both ends of the joint body 12, respectively, and for this purpose, insertion holes 24, 24 for the pipes (copper pipes 22) are provided, which open at both ends. A ring-shaped protrusion 26 as a stopper means is integrally formed on the inner circumferential surface of the joint body 12 between the insertion holes 24, 24, protruding from the inner circumferential surface at a predetermined height so as to be located at the axial center of the joint body 12. The protrusion 26 is intended to prevent the movement of the copper pipe 22 by contacting the tip of the inserted copper pipe 22, as described later.

[0028] The insertion hole 24 of the joint body 12 is opened in a stepped form in which the diameter gradually increases toward the end of the joint body 12. An inlet side female thread 28 into which the pressure bush 20 is screwed is provided on the inner peripheral surface of the end opening where the inner diameter of the insertion hole 24 is the largest, and an inner female thread 30 into which the thread collar 16 is screwed is provided at an intermediate position between the opening and the protrusion 26. A tapered portion 24a consisting of an inclined surface that inclines toward the end opening of the joint body 12 and expands in diameter is provided between the insertion hole 24 located at the most central part in the axial direction and the innermost stepped part that provides the smallest inner diameter, so that the free elastic deformation of the restriction ring 14 in the radially outward direction is not hindered.

[0029] Further, the restriction ring 14 is formed in the form shown in Figs. 4(a)-(c) by bending the tongue-shaped locking claws 14b at their bases using the restriction ring precursor 14' shown in Figs. 3(a)-(c). Specifically, the restriction ring precursor 14' is configured to have a ring body 14a having a predetermined width and a plurality of (here, 12) plate-shaped locking pieces 14b having a predetermined width, which are integrally extended from the inner periphery of the ring body 14a toward the center of the ring body and are radially arranged at predetermined intervals in the circumferential direction. Here, the bases of the locking pieces 14b are configured as narrow width portions 32 having a width x narrower than the width y of the tip side. The restriction ring precursor 14' in this form can be easily manufactured, for example, by punching a predetermined elastic metal plate with a press.

[0030] The restriction ring precursor 14' has its multiple locking claws 14b bent at the narrow portion 32 at its base toward the front in the insertion direction of the copper tube 22, which is the connected tube, and inclined at a predetermined angle α, for example, about 30° to 40°, with respect to the plane perpendicular to the axis of the joint body 12, in other words, with respect to the plate surface of the ring body 14a, thereby forming the restriction ring 14 shown in Fig. 4. The inner diameter of the restriction ring 14 formed at the tips of the bent locking claws 14b of the restriction ring 14 is designed to be smaller than the outer diameter of the copper tube 22. The restriction ring is made of a hard metal material having elasticity, such as SUS301, that can exhibit elastic properties, so that the locking claws 14b can dig into, or in other words, catch on, the outer surface of the copper pipe 22 when the copper pipe 22 connected by the pipe joint 10 is pulled out, thereby making the locking claws 14b elastically deformable. Also, by making the restriction ring 14 out of a metal material such as SUS301, it is possible to advantageously maintain the necessary pull-out prevention force for a long period of time.

[0031] 1, the restriction ring 14 is disposed in a fixed position in such a manner that it abuts against the stepped portion at the innermost part of the insertion hole 24 in the joint body 12. As a result, when the copper tube 22, which is the connected pipe body, is inserted into the insertion hole 24 of the fitting body 12, the locking claws 14b of the regulating ring 14 are elastically pushed outward in the radial direction by the insertion force of the copper tube 22. At that time, since the base of the locking claws 14b is made into the narrow portion 32, the bending deformation resistance of that portion is effectively reduced, so that the copper tube 22 can be inserted into the regulating ring 14 without applying a large pushing force to the copper tube 22. On the other hand, after the copper tube 22 is inserted, the tip of the locking claws 14b is made into a pin angle at the corner on the side that contacts the copper tube 22, so that it bites into or gets caught on the outer surface of the copper tube 22, and therefore, even if a pulling force is applied to the copper tube 22, it can be effectively prevented from slipping out.

[0032] In this way, by forming the locking claws 14b of the regulating ring 14 as narrow portions 32 at their bases, it is possible to advantageously reduce the reaction force due to the elastic deformation of the locking claws 14b. The width x of the narrow portions 32 is appropriately selected depending on the deformation resistance of the locking claws 14b. However, if the width is too narrow, problems such as buckling may occur. Therefore, in general, the ratio (x / y) of the width x of the narrow portions 32 at the bases of the locking claws 14b to the width y of the tip portions of the locking claws 14b is set to a value of about 0.2 to 0.9, preferably about 0.3 to 0.8. In order to satisfy such a ratio, the width x of the narrow portion 32 of the locking claw 14b is generally set to 0.6 to 1.6 mm, and the width y of the tip of the locking claw 14b is generally set to 1.6 to 3.0 mm. Furthermore, the thickness of the locking claw 14b is set to a value within the range of 0.5 to 1.0 mm, which is smaller than the width x of the narrow portion 32.

[0033] 5(a) and (b), the thread collar 16 is made of a metal tube having a thick-walled cylindrical shape, and on its outer circumferential surface, a male thread portion 16a and a stepped portion are formed in a form parallel to the axial direction. Four tool holes 16b are formed with a phase difference of 90° so as to open on the end face on the side on which the male thread portion 16a is formed. Furthermore, the inner part of the end opposite to the side on which the tool holes 16b are formed is configured as a protrusion 34 that protrudes outward in the axial direction, and the outer circumferential portion of this protrusion 34 is a tapered portion that extends at an angle toward the center.

[0034] The thread collar 16 is turned with a tool using the tool hole 16b, so that the male thread portion 16a on its outer periphery is screwed into the internal female thread portion 30 on the inner surface of the insertion hole 24 of the joint body 12, thereby clamping and fixing the ring body 14a of the restriction ring 14 between the stepped portion provided at the innermost part of the insertion hole 24 of the joint body 12, as shown in Fig. 1. The stepped portion on the outer periphery of the thread collar 16 abuts against the stepped portion on the inner periphery of the insertion hole 24 of the joint body 12, so that further screwing can be prevented in a state in which the restriction ring 14 is fixed and held with a predetermined tightening force, and the inner hole 16c has an inner diameter large enough to allow the copper pipe 22 to be inserted therethrough.

[0035] Furthermore, the protrusion 34 provided on the end of the screw collar 16 on the side where the regulating ring 14 is placed has a tapered inclined surface that suppresses or prevents large deformation of the locking claws 14b when a pull-out force is applied to the copper tube 22, thereby advantageously increasing the pull-out prevention force for the copper tube 22.

[0036] In this way, the threaded collar 16 fixes the regulating ring 14 and advantageously suppresses or prevents the locking claws 14b from being significantly deformed by the pulling force of the copper tube 22. It also contributes to the fixing of the O-ring 18 described later, and functions as a guide for the connected copper tube 22. It also has a vibration-damping effect that reduces the transmission of vibrations of the copper tube 22 to the regulating ring 14 and the O-ring 18 when the copper tube 22 vibrates.

[0037] The O-ring 18 is a ring with a circular cross section made of a rubber material such as IIR or H-NBR, and as shown in Fig. 1, two O-rings 18, 18 with different wire diameters but the same inner diameter are arranged with a circular plate-shaped spacer 36 sandwiched between them, and are arranged so that they are positioned axially outside the restriction ring 14 and threaded collar 16 of the insertion hole 24 and exposed to the inner surface of the insertion hole 24 by being pressed by a pressure bushing 20 screwed onto the inner peripheral portion of the end of the joint body 12. The inner diameter of the two O-rings 18, 18 is made smaller than the outer diameter of the copper tube 22 so that a seal between the O-rings and the outer peripheral surface of the inserted copper tube 22 can be effectively achieved. Also, since the two O-rings 18, 18 have different wire diameters, a stepped portion is formed on the inner surface of the fitting body 12 so that the inner diameter on the side where the O-ring 18 with the smaller wire diameter is placed is smaller, thereby allowing the two O-rings 18, 18 to be placed at the same inner diameter.

[0038] 6(a) and 6(b), the pressure bushing 20 is made of the same metal material as the joint body 12, has a thick-walled cylindrical shape, and has an insertion hole 20a large enough to insert a copper tube 22 as an inner hole. The pressure bushing 20 has a knurled portion 20b on the outer circumferential surface of the cylindrical wall thereof, which is knurled to be held by the operator's hand, and a male screw portion 20c that is screwed into the inlet female screw portion 28 of the joint body 12, with a circumferential groove of a predetermined depth therebetween. A ring-shaped hollow portion 20d is formed to a predetermined depth so as to open on the end face of the pressure bushing 20 on the side where the knurled portion 20b is provided, thereby reducing the weight of the pressure bushing 20. The pressure bushing 20 is screwed at its male thread portion 20c into the inlet female thread portion 28 of the fitting body 12, so that the pressure bushing 20 can be attached in a form having an outer shape that is small enough to be smaller than the outer shape of the fitting body 12, as shown in FIG. 1, thereby making it possible to make the entire pipe fitting 10 compact.

[0039] 1, the male threaded portion 20c of the pressure bushing 20 is screwed into the inlet side female threaded portion 28 of the joint body 12, and the pressure bushing 20 is attached to the end of the joint body 12, so that the two O-rings 18, 18 arranged via a spacer 36 are pressed by the screw-in end face of the pressure bushing 20, and the O-rings 18, 18 are accommodated and held in the end of the joint body 12 in a state in which they are sandwiched between the thread collar 16 and the spacer 36. In this state, the two O-rings 18, 18 are not compressed and deformed, so that no large insertion resistance occurs when the copper tube 22 is inserted.

[0040] When an operator holds a copper tube 22, which is a pipe to be connected, with his bare hands and inserts and connects it to the pipe fitting 10 assembled in the form shown in Fig. 1, the copper tube 22 is advanced further from the position shown in Fig. 1 and further from the position shown in Fig. 7(a) to be inserted into the pipe fitting 10, and the copper tube 22 is inserted further into the pipe fitting 10 after passing through the O-rings 18, 18 and the threaded collar 16 from the insertion hole 20a of the pressure bush 20. As a result, the copper tube 22 is pushed into the restriction ring 14, but since the base of the locking claws 14b of the restriction ring 14 is made into the narrow portion 32 and can be easily pushed outward, the copper tube 22 can be easily pushed into the restriction ring 14. As the copper tube 22 advances further, the tip of the copper tube 22 comes into contact with the protrusions 26 provided on the inner surface of the fitting body 12, thereby restricting the insertion length of the copper tube 22. Meanwhile, the locking claws 14b of the restricting ring 14 elastically come into contact with the outer surface of the copper tube 22, and the locking claws 14b bite into the outer surface of the copper tube 22 at the pin-angled corners at their tip. As a result, even if a pull-out force is applied to the copper tube 22, a large pull-out resistance can be exerted, and thus an excellent pull-out prevention force for the copper tube 22 is achieved.

[0041] Next, as described above, in a state in which the copper tube 22 abuts against the ring-shaped ridge 26 on the inner surface of the joint body 12 and is prevented from moving further, the pressure bushing 20 is rotated by the operator using the knurled portion 20b for rotation provided on its outer periphery to further advance the screwing, whereby the two O-rings 18, 18 are pressurized and compressed in the axial direction of the insertion hole 24 by the pressing force exerted by the abutment of the end faces of the pressure bushing 20. This causes the O-rings 18, 18 to bulge radially inward, increasing the pressing force against the outer periphery of the copper tube 22. As a result of the pressure and compression action caused by further screwing in of the pressure bushing 20, the O-rings 18, 18 take on a roughly rectangular cross-sectional shape as shown in Figure 7(b).As a result, the O-rings 18, 18 are strongly pressed against the outer circumferential surface of the copper tube 22 while increasing the pressure contact area, thereby further improving the seal between the outer circumferential surface of the copper tube 22 and the inner surface of the insertion hole 24.

[0042] The compression ratio of the O-ring 18 is generally recognized as being most effective in terms of pressure resistance and durability, and is set to approximately 25%±5%. The O-rings 18, 18 are pressed against the end face of the pressure bushing 20 so that such a compression ratio is achieved, in other words, so that the final compression ratio (%) is realized.

[0043] Therefore, with the pipe fitting 10 configured as described above, when connecting the copper pipe 22 to be connected, the worker need only grasp the copper pipe 22 with his bare hands and insert the end of the pipe through the insertion hole 20a of the pressure bushing 20 and into the insertion hole 24 of the fitting body 12, thereby easily and simply completing the connection. This not only eliminates the need to use fire, as in the conventional brazing method, but also completely eliminates the need to use special tools for crimping work, as in the conventional crimping method. Therefore, all of the various problems caused by the use of fire and special tools can be completely eliminated.

[0044] Moreover, the insertion operation of the copper tube 22 is performed by pushing the multiple locking claws 14b of the regulating ring 14 radially outward. Since the locking claws 14b have narrow portions 32 at their bases, which make it easy to push them radially outward, no large insertion force is required when inserting the copper tube 22 into the regulating ring 14. Therefore, the copper tube 22 can be easily inserted by hand by the worker. In addition, since there is no need to use components such as an induction cylinder, this also contributes to a reduction in the number of parts.

[0045] Therefore, when the outer diameter of the copper tube 22 is increased, the force preventing the copper tube 22 from coming out must be increased, but even in such a case, the structure of the pipe joint 10 as illustrated can advantageously deal with it. In short, the larger the diameter of the copper tube 22 to be connected, the greater the resistance to insertion of the copper tube 22. In order to reduce the resistance to insertion of the copper tube 22, the base of the locking claws 14b of the regulating ring 14 is made narrow 32, and the existence of the narrow 32 allows the locking claws 14b of the regulating ring 14 to be easily expanded. As a result, even if the outer diameter of the inserted copper tube 22 is 19 mm or more, the resistance to insertion can be effectively reduced, and the insertion operation can be advantageously performed by the bare hands of the worker. This reduction in insertion resistance also allows the number of restriction rings 14 to be increased.

[0046] The above-mentioned features of the present invention are also evident from the experimental results shown in Table 1 below. That is, in this experiment, the restriction rings 14 used in the pipe joint 10 shown in Fig. 1 were prepared with different thicknesses, tip widths, base narrow widths, and numbers of the locking claws 14b as shown in Table 1 below, and three of them were arranged in a three-tiered configuration with a spacer interposed therebetween, and the wire diameters and inner diameters of the two O-rings 18, 18 were the same, except that the pipe joint 10 was constructed as in Fig. 1. Then, the insertion resistance of a copper tube 22 with an outer diameter of 22.22 mm into each pipe joint 10 was examined. In addition, in the prepared pipe joint 10, the dimensions of the O-ring 18 were: outer diameter: 31.22 mm, inner diameter: 21.22 mm, thickness: 5.0 mm. In addition, the initial compression rate of the O-ring 18 was 10%, the final compression rate due to tightening of the pressure bush 20 was 25%, and the tightening allowance of the pressure bush 20 was 1.0 mm. The insertion resistance of the copper pipe 22 into the pipe joint 10 using the restriction rings 14 of various sizes was then investigated, and the evaluation results are shown in Table 1 below.

[0047] [Table 1]

[0048] As is clear from the results of Table 1 above, in the pipe fittings 10 of Experiments 1 to 4, in which the width of the base of the locking claws 14b of the regulating ring 14 is narrower than the width of the tip, and a narrow width portion 32 is provided, it is recognized that the insertion resistance is small and the insertion operation can be performed only with the bare hands of the worker (evaluation: ○) in all cases. In contrast, in the pipe fittings 10 of Experiments 5 and 6, in which the width of the tip and the width of the base of the locking claws 14b are the same and no narrow width portion 32 is provided, it is recognized that the insertion resistance is large and it is difficult to insert the fittings using only the bare hands of the worker (evaluation: ×).

[0049] In addition, the pipe fittings 10 of Experiments 1 to 4 used in the above-mentioned insertion resistance evaluation test were each pulled up to a limit load of 11.7 kN using a tensile testing machine to evaluate the pull-out prevention force. It was found that in none of the pipe fittings 10 did the copper pipe 22 come out, and furthermore, no leakage occurred even when a specified pressure was applied in an airtightness test.

[0050] Although typical embodiments of the present invention have been described in detail above, it should be understood that these are merely examples, and that the present invention should not be construed in any way as being limited by the specific descriptions of such embodiments.

[0051] For example, in the above-described embodiment, a pipe fitting for linearly connecting two copper pipes 22 as the connected pipes has been described as an example, but the present invention is in no way limited to this, and can be advantageously applied to any of the various types of conventionally known pipe fittings with various names, such as sockets, adapters, tee, T-shaped, Y-shaped, cross-shaped, 90° elbows, etc., which are used to connect a pipe for transporting a fluid such as a liquid or gas to another pipe of a different diameter, or to connect to the target equipment.

[0052] In addition, in the present invention, instead of the pressure bush 20 having the structure as illustrated, a pressure bush 40 having a thinned shape as shown in Fig. 8 can be advantageously used. This pressure bush 40 has a shape in which the cylindrical wall portion located radially outside the hollowed-out portion 20d in the previous pressure bush 20 is removed, and the outer surface of the cylindrical wall portion located radially inside the hollowed-out portion 20d is knurled to form a knurled portion 40b, so that an operator can hold the knurled portion 40b and rotate the pressure bush 20 with bare hands. Note that, like the previous pressure bush 20, the pressure bush 40 has an insertion hole 40a, and a male screw portion 40c that screws into the inlet side female screw portion 28 provided on the inner peripheral portion of the end of the joint body 12 is provided on the outer peripheral surface.

[0053] Furthermore, in the illustrated embodiment, twelve locking claws 14b are provided integrally with the regulating ring 14 at predetermined intervals in the circumferential direction, but the number is appropriately selected in consideration of the insertion resistance and pull-out prevention force of the copper tube 22, and is generally provided at equal intervals in a ratio of 6 to 18. All such locking claws 14b are formed as narrow-width portions 32 at their bases, but the number of locking claws 14b provided with such narrow-width portions 32 is appropriately selected according to the desired insertion resistance, and the insertion resistance of the copper tube 22 can be reduced as the number of locking claws 14b provided with such narrow-width portions 32 increases. As for the width of the narrow-width portions 32 provided at the bases of the locking claws 14b, in addition to the illustrated case in which all the narrow-width portions 32 are provided with the same width, it is also possible to make the width of the narrow-width portions 32 different for each locking claw 14b.

[0054] Furthermore, the number of restriction rings 14 is appropriately selected so that effective pressure resistance and pull-out prevention force can be exhibited depending on the diameter of the copper pipe 22 to be connected and the pressure of the fluid flowing therethrough, and there is no problem with using one stage as in the illustrated embodiment, using three stages as adopted in the performance evaluation, or using other stages. When using a plurality of restriction rings 14 and arranging them in a plurality of stages, they are arranged in the insertion hole 24 of the joint body 12 in a form in which a spacer of a predetermined thickness is interposed between each ring body 14a to avoid mutual interference of the locking claws 14b. However, such a spacer is not necessarily required as long as an appropriate interval can be secured between adjacent restriction rings 14, 14. For example, it is possible to form a predetermined gap between them by increasing the thickness of the ring body 14a.

[0055] In the illustrated embodiment, O-rings 18 having different wire diameters (thickness) are used, but it is also possible to use two O-rings 18 having the same wire diameter and inner diameter, which provides advantages such as eliminating the need to provide a stepped portion with a different inner diameter on the inner surface of the fitting body 12.

[0056] In addition, in the method of manufacturing the regulating ring 14, as illustrated, a regulating ring precursor 14' shown in Figure 3 is formed, and then the locking claws 14b are bent at the narrow portion 32 of the base to complete the regulating ring 14 in the form shown in Figure 4. In addition, various known methods can be adopted, such as a method in which the inner diameter shape of the ring body 14a and the locking claws 14b are punched out of a metal plate using a press, the locking claws 14b are then bent at the narrow portion 32 of the base, and then the outer diameter shape of the ring body 14a is punched out of the metal plate by press processing, thereby obtaining the desired regulating ring 14.

[0057] In addition, the connected pipe may be made of any metal material such as aluminum or its alloy, other than the copper pipe 22, and generally, a pipe made of a soft metal material is advantageously used. Furthermore, the material of the restricting ring 14 is not limited to SUS, and a metal material harder than the connected pipe is advantageously used.

[0058] In addition, although we will not list them one by one, the present invention can be implemented in various forms with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art, and it goes without saying that all such implementation forms fall within the scope of the present invention as long as they do not deviate from the spirit of the present invention. [Explanation of symbols]

[0059] 10 Pipe joint 12 Joint body 14 Regulating ring 14a Ring body 14b Locking claw 14' Restriction ring precursor 16 Thread collar 16a Male thread 16b Tool hole 16c Inner hole 18 O-ring 20 Pressure bush 20a Insertion hole 20b Knurled portion 20c Male thread 20d Hollowed out part 22 Copper tube 24 Insertion hole 24a Tapered portion 26 Ridge 28 Inlet side female thread 30 Inside female thread 32 Narrow width part 34 Projection part 40 Pressure bush 40a Insertion hole 40b Knurled portion 40c Male thread portion

Claims

1. a cylindrical joint body having an insertion hole at least on one end side into which a connected pipe is inserted from its pipe end and fixed; a restriction ring disposed in a fixed position within the insertion hole, the restriction ring having a plurality of elastically deformable locking claws positioned at predetermined intervals in the circumferential direction of the insertion hole, the locking claws dig into the outer surface of the connected pipe inserted into the insertion hole to prevent the connected pipe from being pulled out; and a restriction ring disposed axially outward of the insertion hole relative to the restriction ring and exposed within the insertion hole, the restriction ring being disposed axially outward of the insertion hole relative to the insertion hole and exposed within the insertion hole before being inserted into the insertion hole. a sealing means consisting of an O-ring that contacts an outer surface of the connected pipe and seals between the outer surface of the connected pipe and the inner surface of the insertion hole; and a cylindrical pressure bushing that is screwed onto an end of the connected pipe insertion side of the joint body, and has an insertion hole formed in the axial direction of the connected pipe that is inserted into the insertion hole, and that is screwed onto the end of the connected pipe insertion side of the joint body, and as the screwing progresses, the O-ring is pressurized and compressed in the axial direction of the insertion hole, causing the O-ring to bulge radially inward, thereby improving the pressing ability against the outer surface of the connected pipe, a pressure-resistant pipe joint characterized in that the regulating ring has a ring body in the shape of a circular ring plate of a predetermined width that is held in a fixed position within the insertion hole of the joint body, and the multiple locking claws are arranged so as to extend integrally from the inner circumference of the ring body toward the center of the ring body, and at least one of the multiple locking claws has a narrow portion at its base that is narrower than the width of the tip portion that bites into the outer surface of the connected pipe, and is bent at the narrow portion so as to be inclined forward in the insertion direction of the connected pipe.

2. 2. A pressure-resistant pipe fitting as described in claim 1, characterized in that the regulating ring is abutted against a stepped portion formed on the inner surface of the insertion hole by a thread collar member that screws into a threaded portion provided on the inner surface of the insertion hole, and is clamped and fixed therein.

3. 2. A pressure-resistant pipe joint according to claim 1, characterized in that the pressure bush is attached by being screwed into a threaded portion provided on an inner peripheral portion of an end portion of the joint body on which the connected pipe is inserted.

4. 4. A pressure-resistant pipe joint as claimed in claim 3, characterized in that the pressure bushing has a knurled outer surface, and the pressure bushing can be screwed in by hand by gripping the knurled portion.

5. A pressure-resistant pipe joint as described in claim 1, characterized in that a plurality of the O-rings are arranged in the axial direction of the insertion hole with annular spacers interposed between adjacent O-rings.

6. 2. The pressure-resistant pipe joint according to claim 1, further comprising a stopper means provided on the inner surface of the insertion hole deeper than the position of the regulating ring, against which the connected pipe inserted into the insertion hole abuts to prevent its movement.

7. 2. The pressure-resistant pipe joint according to claim 1, characterized in that the insertion holes are provided at both ends of the joint body, and the two connected pipes are connected to each other by inserting and fixing the connected pipes into the insertion holes using the regulating ring, the sealing means and the pressure bushing.

8. 8. The pressure-resistant pipe joint according to claim 1, wherein the connected pipe is a large-diameter pipe having an outer diameter of 19 mm or more.

Images