A pipe joint made of resin

Abstract: The present invention relates to a pipe joint made of resin used for laying pipes in which a high-purity liquid, ultra pure water or the like flow. According to the pipe joint made of resin in the present invention, a sealing surface pressure is generated in both axial and radial directions, thereby availing to keep an excellent sealing property for a long period, and facilitate controlling a torque for fastening the pushing ring. The pipe joint made of resin according to the present invention comprises a joint body (1) having a receiving port (11), a cylindrical portion (12), an annular groove portion (13) and a stepped surface (14). An inner ring (3) forcedly inserted by the pushing ring (5) is provided with an outer projection (34), an inner projection (35) and an annular recessed portion (36). On at least one portion among axially opposed portions (A1, A2, and A3) of each surface, an axial sealing portion S10 is disposed. On at least one portion among radially opposed portions (B1, B2, and B3) of each surface, an radial sealing portion R10 is disposed. The joint body (1), the inner ring (3) and the pushing ring (5) are individually made of an optional synthetic resin selected among PFA, PTFE, ETFE, CTFE, and ECTFE.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint made of resin, in particular, applied to laying pipes for a high-purity liquid and ultra pure water treated in production process in various kinds technical fields such as production of semiconductor, medical supplies and medicines, food process, and chemical industry. 2. Description of the Prior Art Conventionally, such a kind of pipe joint made of resin having a structure shown in FIG. 8 has been well known. The pipe joint made of resin comprises a joint body 81, an inner ring 82 and a pushing ring 83. The joint body 81 has a receiving port 84, a tapered receiving surface 85 projecting from a base portion of the receiving port 84, and a tapered receiving surface 86 disposed on a tip portion of the receiving port 84. Additionally, an outer periphery of the receiving port 84 is provided with a male thread portion 87. The inner ring 82 includes a connecting portion 89 having a swelling portion 88 whose section is chevron-shaped, and a protruding portion 90. A tip of the protruding portion 90 is provided with a tapered abutting surface 91. The pushing ring 83 includes a pressing portion 92. According to this pipe joint made of resin, a diameter of an end of a pipe material 7 made of resin forcedly inserted in the connecting portion 89 is increased, thereby forming a tapered abutting surface 93 on an outer peripheral surface of the pipe material 7. The end of the pipe material 7 is forcedly inserted into the connecting portion 89, the inner ring 82 connected to the pipe material 7 is forcedly inserted in the receiving port 84 of the joint body 81 with the result that a female thread portion 94 of the pushing ring 83 previously fitted in the pipe material 7 is threadedly connected to a male thread portion 87 of the receiving port 84, thus being fastened. Then, the pressing portion 92 of the pushing ring 83 pushes the inner ring 82 in a pressing direction, and the abutting surface 91 of the inner ring 82 forcedly abuts against the receiving surface 85 of the joint body 81, thereby forming an axial primary sealing portion S1, and the abutting surface 93 of the pipe material 7 forcedly abuts against the receiving surface 86 of the receiving port 84, thereby forming axial secondary sealing portion S2. In the conventional pipe joint made of resin referring to FIG. 8, the pushing ring 83 is fastened, thus generating a pressing-directional pressing force. Consequently, a sealing surface pressure in an axial direction is generated on two portions of the primary sealing portion S1 and the secondary sealing portion S2. In such a pipe joint made of resin, a creep and a stress relaxation are generated with time on the joint body 81 made of resin and the pushing ring 83, the pipe material 7 or the like, whereby the sealing surface pressures of the primary sealing portion S1 and the secondary sealing portion S2 are decreased with the result that there has been a fear wherein sealing property is relatively early lost. Furthermore, in order to secure a predetermined sealing property, an amount of threadedly connecting the pushing ring 83, a fastening torque or the like are controlled in high accuracy, a fastening force generated by the pressing ring 83 has been required to be strictly set at a predetermined magnitude. Therefore, there is a problem wherein an operation efficiency is lowered and a high technique and skill are required in operation. EP 0872678 A1, which is published after the application date of this invention but which is considered to the prior art under Art. 54 (3) EPC, discloses a pipe joint with a cylindrical collar member interposed between the tube inserted and fitted to the insert section and the opening of the joint body. The collar member comprises a thick-walled section in a sealing function abutting against tube and against the inner cylindrical surface of the pipe joint. This collar member is an additional part which increases the costs of the tube joint. SUMMARY OF THE INVENTION The present invention has been conducted in view of the above mentioned circumstances. It is an object of the present invention to provide a pipe joint made of resin which enables early sealing property to be kept for a long time. It is another object of the present invention to provide a pipe joint made of resin wherein a radial sealing surface pressure is generated, thereby exhibiting an excellent sealing property regardless of an amount of fastening the pushing ring and a fastening torque, and the sealing property owing to a creep and a stress relaxation is not easily deteriorated. It is still another object of the present invention to provide a pipe joint made of resin wherein neither high technique nor skill is required in working operation. The present invention provides a pipe joint made of resin including a joint body defining an inside area, an inner ring, and a pushing ring, an end portion of a pipe being adapted for insertion in said inside area of said joint body, the end portion of the pipe being pressed by said pushing ring against said joint body in said inside area of said joint body, thereby connecting the pipe to said joint body, that pipe joint comprising: a cylindrical receiving port disposed on an end portion thereof; said joint body further comprising a cylindrical portion protruding from an end portion thereof and inside of the said cylindrical receiving port concentrically therewith, said cylindrical receiving port and said cylindrical portion defining an annular groove between them; wherein: said inner ring is sleeve-shaped and has a connecting portion and a protruding portion, said inner ring being insertable in the said receiving port, such that said connecting portion is forcedly inserted in the end portion of the pipe so as to be connected to the pipe, said protruding portion protruding from the end portion of the pipe and in said receiving port when said connecting portion is connected to the end of the pipe; said protruding portion has an annular outer projection and an annular inner projection both axially protruding therefrom, said annular outer projection being inserted in said annular groove on the outside of said cylindrical portion by inserting said protruding portion of said inner ring in said receiving port, said annular inner projection being inserted on the inside of said cylindrical portion by inserting said protruding portion of said inner ring in said receiving port, said annular outer projection and said annular inner projection defining an annular recessed portion disposed between said annular outer projection and said annular inner projection; said pushing ring has a pressing portion disposed thereon and is threadedly connected to said cylindrical receiving port, said pushing ring applying a pressing force with said pressing portion for pressing against said inner ring when said inner ring is connected to the end portion of the pipe and said cylindrical protruding portion is inserted in said receiving port, and when said pushing ring is threadedly connected to said receiving port; said joint body further comprising an annular stepped surface which protrudes from a base of said cylindrical portion in an inwardly radial direction; said cylindrical portion has an end surface; said annular inner projection has an end surface; said annular recessed portion has a bottom surface; and said annular groove has a grooved bottom surface. The pipe joint is characterized in that when said pressing force is applied to said inner ring by the pressing portion of said pushing ring, (i) said annular stepped surface is axially opposed to said end surface of said annular inner projection, (ii) said end surface of said cylindrical portion is axially opposed to said bottom surface of said annular recessed portion, (iii) said grooved bottom surface of said annular groove is axially opposed to said end surface of said annular outer projection, with the result that three axially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the axially opposed portions thereby forming an axial sealing portion, and (iv) said abutting surface on a side of the pipe forcedly abuts against the receiving surface of the joint body, thereby forming an axial sealing portion, and the pressing portion of the pushing ring forcedly abuts against the receiving surface on a side of the pipe, thereby forming an axial sealing portion. Further developments of the invention are subject of dependant claims. prefer- Thus when the pressing force is applied to the inner ring by the pressing portion of the pushing ring, an annular stepped surface disposed on the joint body, protruding from a base portion of the cylindrical portion to an inwardly radial direction, is axially opposed to an end surface of the inner projection, an end surface of the cylindrical portion is axially opposed to a bottom surface of the annular recessed portion and a grooved bottom surface of the annular groove portion is axially opposed to an end surface of the outer projection, with the result that three axially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the axially opposed portions thereby forming an axial sealing portion. Thus, at least one portion among the three axially opposed portions is provided with an axial sealing portion. The sealing surface pressure generated on the axial sealing portion keeps the sealing property. When the pressing force is applied to the inner ring by the pressing portion of the pushing ring, an inner peripheral surface of the cylindrical portion is radially opposed to an inside surface of the annular recessed portion, an inside surface of the annular groove portion is radially opposed to an inner peripheral surface of the outer projection, and an outside surface of the annular groove portion is radially opposed to an outer surface of the outer projection, with the result that three radially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the radially opposed portions, thereby forming a radial sealing portion. Thus, at least one portion among the three axially opposed portions is provided with a radial sealing portion. The sealing surface pressure generated on the radial sealing portion keeps the sealing property. The sealing surface pressure generated on the radial sealing portion is generated regardless of.an amount of fastening the pushing ring and a fastening torque. When the pressing force is applied to the inner ring by the pressing portion of the pushing ring, an annular stepped surface disposed on the joint body, protruding from a base portion of the cylindrical portion to an inwardly radial direction, is axially opposed to an end surface of the inner projection, an end surface of the cylindrical portion is axially opposed to a bottom surface of the annular recessed portion and a grooved bottom surface of the annular groove portion is axially opposed to an end surface of the outer projection, with the result that three axially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the axially opposed portions thereby forming an axial sealing portion, and when the pressing force is applied to the inner ring by the pressing portion of the pushing ring, an inner peripheral surface of the cylindrical portion is radially opposed to an inside surface of the annular recessed portion, an inside surface of the annular groove portion is radially opposed to an inner peripheral surface of the outer projection, and an outside surface of the annular groove portion is radially opposed to an outer surface of the outer projection, with the result that three radially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the radially opposed portions, thereby forming a radial sealing portion. Thus, at least one portion among the three axially opposed portions is provided with an axial sealing portion. The sealing surface pressure generated on the axial sealing portion keeps the sealing property. Moreover, at least one portion among the three radially opposed portions is provided with a radial sealing portion. The sealing surface pressure generated on the radial sealing portion keeps the sealing property. The sealing surface pressure generated on the radial sealing portion is generated regardless of an amount of fastening the pushing ring and a fastening torque. A bulged portion is annularly disposed on an outer surface of the outer projection, and the outside surface of the annular groove portion may be overlapped with the bulged portion so as to form the radial sealing portion. Moreover, a number of bulged portions may be axially arranged in line, on the outer surface of the outer projection. Thus, the sealing surface pressure of the radial sealing portion is concentrated on an overlapping portion wherein the outer surface of the annular groove is overlapped with the bulged portion, thereby exhibiting the excellent sealing property. By the connecting potion of the inner ring, a diameter of the pipe material in which the connecting portion is forcedly inserted, is increased, the outer surface of the pipe material is provided with a swelling portion whose section is chevron, including a tapered abutting surface whose diameter is decreased as going to a tip of the pipe material and a tapered receiving surface whose diameter is increased as going to a tip of the pipe material, a tip of the receiving port is provided with a tapered receiving surface forcedly abutting against the abutting surface, in a state of widening toward a tip thereof, and a radially smaller end portion of the receiving surface on a side of the pipe material, whose diameter is smaller than the other end portion thereof, is subjected to the pressing force for pressing it in a pressing direction by the pressing portion of the pushing ring. Thus, the abutting surface on a side of the pipe material forcedly abuts against the receiving surface on a side of the receiving port, thereby forming the primary sealing portion S1 shown in FIG. 8, and the pressing portion of the pushing ring forcedly abuts against the radially smaller end portion of the receiving surface on a side of the pipe material. A cylindrical overlapping piece overlapped with the receiving surface may be continuously formed on the pressing portion of the pushing ring, by mounting the overlapping piece on the receiving surface on a side of the pipe material to increase the diameter in a state of widening a tip thereof. Thus, a friction resistance is generated between the receiving surface on a side of the pipe material and a cylindrical overlapping piece whose diameter is increased as going to the tip thereof to be overlapped with the receiving surface, thereby preventing the pushing ring from being loosened. The stepped surface may be overlapped with an end surface of the inner projection, thereby forming the axial sealing portion. By adopting this structure, a liquid passing through the axial sealing portion and a pipe path subsequently, does not intrude into a gap between the end surface of the cylindrical portion and the bottom surface of the annular recessed portion, which are axially opposed to each other, a gap between the grooved bottom surface of the annular groove portion and the end surface of the outer projection, which are axially opposed to each other, a gap between the inner peripheral surface of the cylindrical portion and the inside surface of the annular recessed portion, which are radially opposed to each other, a gap between the inside surface of the annular groove portion and the inner peripheral surface of the outer projection which are axially opposed to each other and a gap between the outside surface of the annular groove portion and the outer surface of the outer projection, which are opposed to each other, thereby preventing the liquid from staying on a pipe connecting portion. In case that the stepped surface is overlapped with an end surface of the inner projection, a shape of the overlapping portion can be variously selected. It is allowed to select any one of the following cases. In case that the above stepped surface and the end surface of the inner protrusion are formed as a flat surface, the overlapping surface is flat. In case that the above stepped surface and the end surface of the inner protrusion are formed in a stepped state, the overlapping surface is stepped. In case that the above stepped surface and the end surface of the inner protrusion are formed in a tapered state, the overlapping surface is tapered. In case that the above stepped surface and the end surface of the inner protrusion are formed in a radially wavelike state, the overlapping portion is wavelike. The cylindrical portion is supported by the inner projection, from a radially inward direction. In this arrangement, the cylindrical portion on a side of the joint body is supported by the inner projection on a side of the inner ring, from a radially inward direction. Therefore, even if the cylindrical portion is going to be deformed so as to fall down in a direction of decreasing the diameter, under the influence of a case wherein the outer projection on a side of the inner ring is forcedly inserted in the annular groove portion on a side of the joint body, a force for causing such a deformation of the cylindrical portion is received by the inner projection on a side of the inner ring, thereby preventing the cylindrical portion from falling and being deformed in a direction of decreasing the diameter. As the result of it, this is useful for restricting decrease of the sealing property owing to creep. The pipe joint made of resin mentioned above, means not only a single pipe joint made of resin for connecting the pipe materials to each other, but also a pipe joint made of resin whose joint body is integrally included by an end of the pipe material or a fluid device. As mentioned above the early sealing property can be kept for a long period without severely controlling a torque for fastening the pushing ring, thereby making it possible to provide the pipe joint made of resin wherein neither high technique nor skill is required in connecting operation. A number of features of the present invention are obviously shown by embodiments as below. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional side view of an embodiment of a pipe joint made of resin according to the present invention. FIG. 2 is a longitudinal sectional side view of a pushing ring. FIG. 3 is an enlarged sectional view of enlarging a main portion of FIG. 1. FIG. 4 is an enlarged sectional view of enlarging each main portion of a joint body and an inner ring. FIG. 5 is a sectional view illustrating a shape of an overlapping portion of an axial sealing portion. FIG. 6 is a sectional view illustrating another shape of the overlapping portion of the axial sealing portion. FIG. 7 is a sectional view illustrating a still another shape of the overlapping portion of the axial sealing portion. FIG. 8 is a longitudinally sectional side view of a conventional pipe joint made of resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing, preferred embodiments of the invention are described below. A pipe joint made of resin as shown in FIGs. 1 and 7 includes a cylindrical joint body 1, a cylindrical inner ring 3, and a cap nut shaped pushing ring 5. The joint body 1, the inner ring 3 and the pushing ring 5 are individually made of a synthetic resin such as PFA (perfluoro-alkoxyfluoro plastics), PTFE (polytetrafluoroetylene), ETFE (etylene-tryfluoro-etylene), CTFE (chloro-tryfluoro-etylene), ECTFE (etylene-chloro-tryfluoro-etylene), having a superior feature in resistance to chemicals and resistance to heat. The joint body 1 has a cylindrical receiving port 11 on at least axial one end portion thereof. The joint body 1 is provided with a short cylindrical portion 12 protruding to an inside of the receiving port 11, and being concentrical with the receiving port 11, an annular groove portion 13 disposed between the cylindrical portion 12 and the receiving port 11, and an annular stepped surface 14 protruding from a base of the cylindrical portion 12 to a radial direction. Moreover, on a tip of the receiving port 11, a receiving surface 15 which is tapered so as to be widened toward a tip thereof and concentrical with the receiving port 11, is disposed. Furthermore, the receiving port 11 has a male thread portion 16 on an outer peripheral portion thereof. The inner ring 3 is formed so that an inner diameter thereof may have the same measurements as an inner diameter of the pipe material 7 made of synthetic resin and an inner diameter of the joint body 1. Therefore, when the inner ring 3 as shown in FIG. 1 is employed, so as to connect the pipe material 7 to the pipe body 1, a fluid (or a liquid) flows smoothly inside each path of the pipe material 7, the inner ring 3 and the joint body 1. As shown in FIG. 1, the inner ring 3 includes a connecting portion 31 connected to the pipe material 7 by being forcedly inserted in an end of the pipe material 7, and a protruding portion 32 projected from the end of the pipe material 7 when the connecting portion 31 is connected to the end of the pipe material 7. The connecting portion 31 of the inner ring 3 includes a swelling portion 33 whose section is chevron. When the connecting portion 31 is forcedly inserted into an end of the pipe material 7, the diameter of the forcedly inserted pipe material 7 of the connecting portion 31 is increased, thus forming a tapered abutting surface 71 whose diameter is decreased as going to a tip of the pipe material 7 and a tapered receiving surface 72 whose diameter is increased as going to a tip of the pipe material 7. By inserting the protruding portion 32 in the receiving port 11, the protruding portion 32 is protrusively provided with an annular outer projection 34 which is inserted in the annular groove portion 13 arranged outside the cylindrical portion 12, and an annular inner projection 35 inserted in an inside of the cylindrical portion 12, in an axial direction. An annular recessed portion 36 is disposed between the outer projection 34 and the inner projection 35. Additionally, as shown clearly in FIGs. 3 and 4, on an outer peripheral surface 37 of the outer projection 34, a number of bulged portions 38 (for example, three bulged portions in the figure) being annular, are axially disposed at intervals. Though a section of the bulged portions 38 illustrated in the figure is trapezoid, it may be arc-shaped. Moreover, the number of the bulged portions may be one or three or more. The pushing ring 5 has a female thread portion 52 on an inner peripheral portion of an outer ring portion 51. Additionally, an annular pressing portion 53 protruding to a radially inward direction is continuously formed on an outer end portion of the outer ring portion 51, a cylindrical overlapping piece 54 and a cylindrical protruding piece 55 are respectively continuously formed on an axially inward side and an axially outward side of an inner peripheral side of the pressing portion 53. The inner diameter of the pressing portion 53 has measurements which enable the pressing portion 53 to be fitted in the pipe material 7, and is equal to that of the end on a radially smaller side of the receiving surface 72 on a side of the pipe material 7. Furthermore, the diameter of the cylindrical overlapping piece 54 can be increased owing to a feature of the resin. According to the above pipe joint made of resin, as shown in FIG. 1, the connecting portion 31 is forcedly inserted into an end portion of the pipe material 7 thereby inserting the protruding portion 32 of the inner ring 3 connected to the pipe material 7 into the receiving port 11 of the joint body 1, whereby the female thread portion 52 of the pushing ring 5 previously inserted in the pipe material 7 is threadedly connected to the male thread portion 16 of the receiving port 1 of the joint body 1 by means of screw connection for fastening with the result that the pressing portion 53 of the pushing ring 5 presses the end on the radially smaller side of the receiving surface 72 formed on a side of the pipe material 7. Therefore, the inner ring 3 is subjected to the pressing force in a pressing direction. Furthermore, the pushing ring 5 is fastened, whereby the cylindrical overlapping piece 54 of the pushing ring 5 is mounted on the receiving surface 72 on a side of the pipe material 7. The diameter of the overlapping piece 54 is increased in a state of widening toward a tip thereof whereby the overlapping piece 54 is overlapped with the receiving surface 72. Then, a friction resistance is caused between the overlapping piece 54 and the receiving surface 72, thereby preventing the pushing ring 5 from loosening. When the inner ring 3 is pressed in a pressing direction, a cylindrical portion 12 on a side of the joint body 1 is inserted into the annular recessed portion 36 on a side of the inner ring 3, and the inner projection 35 and the outer projection 34 on a side of the inner ring 3 are respectively inserted in the annular groove portion 13 outside the cylindrical portion 12 and an inside of the cylindrical portion 12. Therefore, as shown in FIGs. 3, 5 to 7, the stepped surface 14 is axially opposed to an end surface 39 of the inner projection 35, an end surface 17 of the cylindrical portion 12 is axially opposed to a bottom surface 41 of the annular recessed portion 36, and a grooved bottom surface 18 of the annular groove portion 13 is axially opposed to an end surface 42 of the outer projection 34. Additionally, an inner peripheral surface 19 of the cylindrical portion 12 is radially opposed to an inside surface 43 of the annular recessed portion 36, an inside surface 21 of the annular groove portion 13 is radially opposed to an inner peripheral surface 44 of the outer projection 34, and an outside surface 22 of the annular groove portion 13 is radially opposed to the outer peripheral surface 37 of the outer projection 34 (in particular, the bulged portions 38 of the outer peripheral surface 37). Herein, as shown in FIG. 3, an axially opposed portion where the stepped surface 14 is axially opposed to the inner projection 39 is designated as A1, an axially opposed portion where an end surface 17 of the cylindrical portion is axially opposed to the bottom surface 41 of the annular recessed portion is designated as A2, and an axially opposed portion where the grooved bottom surface 18 of the annular groove portion is axially opposed to the end surface 42 of the outer projection is designated as A3. In addition, a radially opposed portion where the inner peripheral surface 19 of the cylindrical portion is radially opposed to the inside surface 43 of the annular recessed portion is designated as B1, a radially opposed portion where the inside surface 21 of the annular groove portion is radially opposed to the inner peripheral surface 44 of the outer projection is designated as B2, a radially opposed portion where the outside surface 22 of the annular groove portion is radially opposed to the outer peripheral surface 37 of the outer projection is designated as B3. On at least one portion among axially opposed portions A1 to A3, the opposed surfaces are overlapped with each other so as to form an axial sealing portion, and on at least one portion among radially opposed portions B1 to B3, the opposed surfaces are overlapped with each other so as to form a radial sealing portion. In the figure, the axially opposed portion A1 forms an axial sealing portion S10, and the radially opposed portion B3 forms a radial sealing portion R10. As a means for forming the axial sealing portion S10 on the axially opposed portion A1, the measurements of each surface of the members may be determined so that, when the end surface 39 of the inner projection abuts against the stepped surface 14 by means of pressure, the end surface 17 of the cylindrical portion may be separated from the bottom surface 41 of the annular recessed portion, and the grooved bottom surface 18 of the annular groove portion may be separated from the end surface 42 of the outer projection. Moreover, as a means for forming the radial sealing portion R10 on the radially opposed portion B3, as shown in an assumption line in FIG. 3, an outer diameter of the each bulged portion 38 of the outer peripheral surface 37 of the outer projection is slightly larger than a diameter of outside surface 22 of the annular groove portion, thus forcedly inserting the outer projection 34 in the annular groove portion 13 to make the outer peripheral surface 37 of the outer projection forcedly abut against the outside surface 22 of the annular groove portion. As mentioned above, the axially opposed portion A1 is provided with the axial sealing portion S10, and the radially opposed portion B3 is provided with the radial sealing portion R10, whereby a sealing surface pressure occurred in these sealing portions S10 and R10 keeps a sealing property. In this case, the sealing surface pressure occurred in the radial sealing portion R10 is generated regardless of a fastening amount or a fastening torque of the pushing ring 5, thereby obtaining the stable sealing surface pressure. Consequently, it is not required to strictly control the fastening torque of the pushing ring 5. Moreover, in this embodiment, the pressing portion 53 of the pushing ring 5 presses the inner ring 3 in a pressing direction, the abutting surface 71 on a side of the pipe material 7 forcedly abuts against the receiving surface 15 of the joint body 1, thereby forming an axial sealing portion S20, and the pressing portion 53 of the pushing ring 5 forcedly abuts against the receiving surface 72 on a side of the pipe material 7, thereby forming an axial sealing portion S30 (see FIG. 1). Therefore, there are three axial sealing portions S10, S20 and S30. Consequently, even if the sealing property in axial sealing portion of any portion among them is decreased, the other axial sealing portions exhibit the necessary sealing property. Especially, in this embodiment, on the axially opposed portion A1 where the stepped surface 14 is axially opposed to the end surface 39 of the inner projection, the axial sealing portion S10 is formed, thereby preventing a fluid flowing in the pipe path from entering B1, A2, B2, A3, B3, with the result that the fluid is not retained in the each pipe connecting portion. As mentioned above, in case that, on the axially opposed portion A1, the axial sealing portion S10 is formed, a shape of the portion where the stepped surface 14 is overlapped with the end surface 39 of the inner projection, may be flat as shown in FIG. 3, stepped as shown in FIG. 5, taper as shown in FIG. 6 wherein the diameter is subsequently reduced from a direction of an inner diameter to an axial direction, or radially wavelike as shown in FIG. 7, made of a combination of an axial convex portion and an axial concave portion. According to the present embodiment, the cylindrical portion 12 on a side of the joint body 1 is reinforcedly supported by the inner projection 35 on a side of the inner ring 3 and the stepped surface 14 of the receiving port 11, from a radially inward direction. Owing to it, even if the cylindrical portion 12 is going to be deformed so as to fall down in a direction of decreasing the diameter, under an influence of a case wherein the outer projection 34 on a side of the inner ring 3 is forcedly inserted in the annular groove portion 13 on a side of the joint body 1, a force for causing the deformation of the cylindrical portion 12 is received by the inner projection 35 on a side of the inner ring 3, thereby preventing the cylindrical portion 12 from falling and being deformed in a direction of decreasing the diameter. As the result of it, this is useful for restricting decrease of the sealing property owing to creep. In this embodiment, among three axially opposed portions A1, A2 and A3, the axial sealing portion S10 is formed on the axially opposed portion A1. However, the axial sealing portion may be formed on at least one portion selected among the three axially opposed portions A1, A2, and A3. Similarly, in this embodiment, the radial sealing portion R10 is formed on one radially opposed portion B3 among three radially opposed portions B1, B2 and B3. However, the radial sealing portion may be formed on at least one portion selected among the three radially opposed portions B1, B2, and B3. In addition, either the axial sealing portion or the radial sealing portion may be formed. Furthermore, the radial sealing portion R10 may be formed by making the outer peripheral surface of the outer projection 34 having the straight outer peripheral surface forcedly abut against the outside surface of the annular groove portion.

Claims: A pipe joint made of resin, including a joint body (1) defining an inside area, an inner ring (3), and a pushing ring (5), an end portion of a pipe (7) being adapted for insertion in said inside area of said joint body, the end portion of the pipe being pressed by said pushing ring against said joint body in said inside area of said joint body, thereby connecting the pipe to said joint body, that pipe joint comprising: a cylindrical receiving port disposed on an end portion thereof; said joint body further comprising a cylindrical portion (11) protruding from an end portion thereof and inside of the said cylindrical receiving port (11) concentrically therewith, said cylindrical receiving port and said cylindrical portion (12) defining an annular groove (13) between them; wherein: said inner ring (3) is sleeve-shaped and has a connecting portion (31) and a protruding portion (32) , said inner ring being insertable in the said receiving port, such that said connecting portion is forcedly inserted in the end portion of the pipe so as to be connected to the pipe, said protruding portion protruding from the end portion of the pipe and in said receiving port when said connecting portion is connected to the end of the pipe; said protruding portion (32) has an annular outer projection (34) and an annular inner projection (35) both axially protruding therefrom, said annular outer projection being inserted in said annular groove (13) on the outside of said cylindrical portion by inserting said protruding portion of said inner ring in said receiving port, said annular inner projection (35) being inserted on the inside of said cylindrical portion (12) by inserting said protruding portion of said inner ring in said receiving port, said annular outer projection and said annular inner projection defining an annular recessed portion disposed between said annular outer projection and said annular inner projection; said pushing ring (5) has a pressing portion (53) disposed thereon and is threadedly connected to said cylindrical receiving port, said pushing ring applying a pressing force with said pressing portion for pressing against said inner ring (33) when said inner ring is connected to the end portion of the pipe and said cylindrical protruding portion is inserted in said receiving port (11), and when said pushing ring is threadedly connected to said receiving port; said joint body further comprising an annular stepped surface (14) which protrudes from a base of said cylindrical portion (12) in an inwardly radial direction; said cylindrical portion has an end surface (17); said annular inner projection (35) has an end surface (39); said annular recessed portion (36) has a bottom surface (41); and said annular groove (13) has a grooved bottom surface (18), characterized in that when said pressing force is applied to said inner ring (3) by the pressing portion (53) of said pushing ring, (i) said annular stepped surface (14) is axially opposed to said end surface (39) of said annular inner projection (35), (ii) said end surface (17) of said cylindrical portion (12) is axially opposed to said bottom surface (41) of said annular recessed portion, (iii) said grooved bottom surface (18) of said annular groove (13) is axially opposed to said end surface (42) of said annular outer projection (34), with the result that three axially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the axially opposed portions thereby forming an axial sealing portion, and (iV) said abutting surface (71) on a side of the pipe (7) forcedly abuts against the receiving surface (15) of the joint body (1), thereby forming an axial sealing portion (S20), and the pressing portion (53) of the pushing ring (5) forcedly abuts against the receiving surface (72) on a side of the pipe (7), thereby forming an axial sealing portion (S30). A pipe joint according to claim 1, wherein the stepped surface (14) is overlapped with an end surface of the inner projection, thereby forming the axial sealing portion with the result that the stepped surface and the end surface of the inner projection are formed as a flat surface. A pipe joint according to claim 1, wherein the stepped surface (14) is overlapped with an end surface of the inner projection, thereby forming the axial sealing portion with the result that the stepped surface and the end surface of the inner projection are formed in a stepped state. A pipe joint according to claim 1, wherein the stepped surface (14) is overlapped with an end surface of the inner projection, thereby forming the axial sealing portion with the result that the stepped surface and the end surface of the inner projection are formed in a tapered state. A pipe joint according to claim 1, wherein the stepped surface (14) is overlapped with an end surface of the inner projection, thereby forming the axial sealing portion with the result that the stepped surface and the end surface of the inner projection are formed in a radially wavelike state. A pipe joint according to claim 1, wherein the cylindrical portion (12) is supported by the inner projection (35), from a radially inward direction. A pipe joint according to claim 1, further wherein said cylindrical portion (12) has an inner peripheral surface; said annular recessed portion has an inside surface; said annular groove portion has an inside surface and an outside surface; and said annular outer projection has an inner peripheral surface and an outer surface, such that when said pressing force is applied to said inner ring by the pressing portion of said pushing ring. (i) said inner peripheral surface of said cylindrical portion is radially opposed to said inside surface of said annular recessed portion, (ii) said inside surface of said annular groove portion is radially opposed to said inner peripheral surface of said annular outer projection, and (iii) said outside surface of said annular groove portion is radially opposed to said outer surface of said annular outer projection, with the result that three radially opposed portions are disposed, and the opposed surfaces are overlapped with each other on at least a portion among the radially opposed portions, thereby forming a radial sealing portion. A pipe joint according to claim 7, wherein the cylindrical portion (12) is supported by the inner projection, from a radially inward direction. A pipe joint according to claim 7, further wherein said connecting portion includes a bulged portion annularly disposed on an outer surface thereof; and the outside surface of said annular groove portion is overlapped with said bulged portion to form the radial sealing portion. A pipe joint according to claim 9 further wherein a plurality of bulged portions are axially arranged in line on the outer surface of said connecting portion. A pipe joint according any one of claims 1 to 10 wherein the inner ring and the pushing ring are individually made of an optional synthetic resin selected among PFA, PTFE, ETFE, CTFE, and ECTFE.

Inventors: NISHIO KIYOSHI, NISHIO, KIYOSHI, Nishio, Kiyoshi c/o Nippon Pillar Packing Co.,Ltd.
Applicants: NIPPON PILLAR PACKING, NIPPON PILLAR PACKING CO. LTD.
Application year: 1998
Main classification: F16L47
IPC codes: F16L19, F16L47