Valve with joint for resin pipes

Abstract

To provide a valve with a joint for resin pipes capable of also sufficiently maintaining a fixing force of a resin pipe to a resin pipe connection part while enabling a fixture ring to stay at an original fixture position after the ring is fixed.SOLUTION: In a valve with a joint for resin pipes, a joint part comprising a resin pipe connection part having ruggedness in an outer periphery is provided in a valve main body integrally or separately, a resin pipe is inserted into the resin pipe connection part and a fixture ring is press-fitted from an outer periphery of the resin pipe, such that the resin pipe is fixed to the joint part. In the valve with the joint for resin pipes, a wedge-shaped groove part is formed in an inner periphery of the fixture ring. When press-fitting the fixture ring to the outside of the resin pipe, a part of the resin pipe enters the groove part, a wedge part is formed in the resin pipe, and the wedge part is locked into the groove part. A depth of the groove part in a radial direction is larger than a shrinkage amount of an apex of the wedge part in the radial direction after shrinkage when the resin pipe achieves a limit of a creep state and is shrunk at a maximum.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a valve with a joint for plastic pipes and a joint for plastic pipes, and in particular to a valve with a joint for plastic pipes and a joint for plastic pipes that can prevent the fixing ring from coming off after the plastic pipe is fixed to the joint portion by pressing the fixing ring into the joint portion and can maintain the fixing force of the plastic pipe. [Background technology]

[0002] Conventionally, there has been known a plastic pipe joint having a so-called bamboo shoot groove on the outer periphery of a metal joint for joining (fixing) a pipe body made of synthetic resin such as polyethylene to a predetermined joining object such as a metal valve body.

[0003] The structure of such a joint portion is configured, for example, such that the tip face of the plastic pipe is inserted into the plastic pipe connection portion formed integrally or separately from the metal pipe joint body while expanding in diameter to the outer periphery of the joint portion, and then a ring-shaped fastening member (ring) provided on the plastic pipe is pressed into the joint while fastening the outer periphery of the plastic pipe.

[0004] Plastic pipes can shrink at low temperatures or become thinner over time. As a result, a gap can form between the outer periphery of the plastic pipe and the ring that is pressed into the outer periphery of the plastic pipe inserted into the outer periphery of the metal groove. If external forces such as vibration or impact are applied to the ring or plastic pipe, the ring can loosen or move from its initial fixed position and come out. There is also the risk that the plastic pipe will shrink due to the loosening of the ring, and come off the joint.

[0005] Various joint structures have been proposed to address this problem. In particular, the joint structure disclosed in Patent Document 1 has a recess on the inner circumference of a fastening ring, and a first convex portion is formed in a position facing this recess on a plastic pipe connection portion having a first convex portion and a second convex portion, the first convex portion being higher than the second convex portion, and the plastic pipe is bent radially in the portion sandwiched between the recess and the first convex portion.

[0006] The joint structure of Patent Document 2 discloses a joint structure in which multiple protrusions are formed on an expanded diameter section whose inner diameter increases toward the back of the tightening ring, and the protrusion with the largest outer diameter among the multiple protrusions of different heights is formed in a position facing the expanded diameter section on the inner circumference of the ring. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2015-166601 A [Patent Document 2] JP 2015-152064 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in Patent Document 1, the axial width of the recess on the inner circumference of the ring is made wider than the axial width of the opposing first convex portion, and a large amount of resin material from the resin tube is allowed to enter the recess, preventing the ring from coming off and suppressing the resin material from popping out of the ring at the back.However, in order to sufficiently fill the recess with resin material, the resin tube is bent radially by the tall first convex portion, and the resin material from the resin tube is allowed to enter the recess on the inner circumference of the ring that is opposite the convex portion.

[0009] Therefore, in order to prevent the ring from coming off, it is necessary to deform the plastic tube towards its outer diameter. However, the amount of plastic material filled into the recess of the bamboo shoot groove is reduced by the amount of plastic material that is deformed and forced into the recess, which may reduce the fixing force that fixes the plastic tube to the joint.

[0010] The joint structure of Patent Document 2 has an enlarged portion provided at the rear side of the ring, and as the ring is pressed into the plastic pipe, the inner surface of the ring and the outer surface of the plastic pipe are pressed together, and one end of the plastic pipe that is pressed against the enlarged portion of the ring expands in diameter toward the rear side along the inner diameter of the enlarged portion, and a protrusion formed on the enlarged portion bites into the outer surface of the plastic pipe, and the protrusion biting into the plastic pipe acts as a stopper to prevent the ring from coming off the plastic pipe.

[0011] However, the protrusions on the inner circumference of the ring are formed only on the enlarged portion, and the outer surface of the plastic pipe and the inner surface of the ring are brought into close contact with each other before the protrusions of the enlarged portion are caused to bite into the outer surface of the plastic pipe.Therefore, in order to make it easier to bring the outer surface of the enlarged plastic pipe into close contact with the inner surface of the ring, the height of the convex portion facing the enlarged portion is made greater than the other convex portions, and to the extent that it is made greater than the other convex portions, the resin material on the outer surface of the plastic pipe is more easily filled outward. As a result, there is a risk that the amount of resin material filled into the recesses of the groove, which is necessary to ensure close contact between the inner surface of the plastic pipe and the outer surface of the plastic pipe connection part, will decrease, resulting in a decrease in the fixing force that fixes the plastic pipe to the joint part.

[0012] In addition, the resin material that makes up the resin pipe initially retains an elastic force (internal stress) that attempts to restore it to its original shape in the event of an external deforming force; however, when repeated external stress is applied or when thermal changes are applied, this elastic force (internal stress) gradually decreases (creep), and eventually the internal stress becomes zero (creep limit).

[0013] If the plastic pipe has not yet reached its creep limit, even if it shrinks to a certain extent, its elastic force will be able to hold the ring in a fixed position. However, if the plastic pipe has reached its creep limit, it will no longer be able to exert an elastic force toward the ring, and so the effect of preventing the ring from moving will be significantly reduced. If it is not possible to reliably prevent the ring from coming loose, the fixing force that fixes the plastic pipe to the joint will decrease, and there is a risk that the plastic pipe will come loose from the joint.

[0014] In the joint structures of the above-mentioned documents 1 and 2, no consideration is given at all to preventing the ring from coming loose or to whether the fixing force for fixing the plastic pipe to the joint can be maintained until the plastic pipe reaches its creep limit.

[0015] Therefore, the present invention has been developed to solve the above problems, and its object is to provide a valve with a plastic pipe fitting and a plastic pipe fitting that enable the ring to remain in its original fixed position while sufficiently maintaining the fixing force of the plastic pipe to the plastic pipe connection portion. [Means for solving the problem]

[0016] In order to achieve the above object, the invention of claim 1 is a valve with a fitting for plastic pipes, in which a fitting portion equipped with a plastic pipe connection portion having an uneven outer circumference is provided integrally or separately from a valve body, a plastic pipe is inserted into this plastic pipe connection portion, and a fixing ring is pressed into the outer circumference of the plastic pipe to fix the plastic pipe to the fitting portion, wherein a wedge-shaped groove is formed on the inner circumference of the fixing ring, and when the fixing ring is pressed into the outside of the plastic pipe, part of the plastic pipe enters the groove to form a wedge portion in the plastic pipe, and this wedge portion is engaged in the groove, the valve with a fitting for plastic pipes is characterized in that the radial depth of the groove is greater than the amount of shrinkage of the radial top of the wedge portion after shrinkage when the plastic pipe reaches its creep limit and shrinks to its maximum.

[0017] The invention according to claim 2 is a valve with a joint for a plastic pipe, according to claim 1, further comprising a cross-sectional shape of the groove that is wedge-shaped, inverted V-shaped, or triangular.

[0018] The invention of claim 3 is a valve with a fitting for a plastic pipe, in which, in addition to the configuration of claim 1 or 2, a tapered surface is provided on the valve body side of the fixing ring, the diameter of which increases towards the valve body side, and the ratio of the volume of the resin material in the region where the inner circumference of the ring and the outer circumference of the plastic pipe intersect, which is pushed out by pressing the ring into the plastic pipe, to the sum of the volume of the filling space provided by this tapered surface and the engagement surface of a flange portion provided on the outer circumference of the fitting portion and the total volume of the recessed portion of the plastic pipe connection portion, is 0.8 or more and 1 or less.

[0019] The invention according to claim 4 is a valve with a joint for a plastic pipe, in which a joint part having a plastic pipe connection part with unevenness on the outer periphery is provided integrally or separately from a valve body, a plastic pipe is inserted into this plastic pipe connection part, and a fixing ring is pressed into the outer periphery of the plastic pipe to fix the plastic pipe to the joint part, a wedge-shaped groove is formed on the inner periphery of the fixing ring, and when the fixing ring is pressed into the outside of the plastic pipe, a part of the plastic pipe enters into the groove to form a wedge part in the plastic pipe, and the wedge part is engaged in the groove. In this valve with a fitting for a plastic pipe, a tapered surface is provided on the valve body side of the fixing ring, the diameter of which increases towards the valve body side, and the ratio of the volume of the resin material in the region where the inner circumference of the ring and the outer circumference of the plastic pipe intersect, which is pushed out by pressing the ring into the plastic pipe, to the sum of the volume of the filling space provided by this tapered surface and the engagement surface of a flange portion provided on the outer circumference of the fitting portion and the total volume of the recessed portion of the plastic pipe connection portion, is 0.8 or more and 1 or less.

[0020] The invention of claim 5 is a valve with a fitting for plastic pipes, in which a fitting portion including a plastic pipe connection portion having an uneven outer periphery and a flange portion with which the plastic pipe abuts is provided integrally with or separately from a valve body, a plastic pipe is inserted into this plastic pipe connection portion, and a fixing ring is pressed into the outer periphery of the plastic pipe to fix the plastic pipe to the fitting portion, wherein a wedge-shaped groove portion is formed on the inner periphery of the fixing ring, and when the fixing ring is pressed into the outside of the plastic pipe, part of the plastic pipe enters into the groove portion to form a wedge portion in the plastic pipe, and this wedge portion is engaged in the groove, the valve with a plastic pipe fitting, wherein a tapered surface expanding in diameter toward the valve body side of the fixing ring is provided on the valve body side, the plastic pipe joint portion is provided at a position facing the tapered surface at the boundary with the flange portion, and the groove portion is provided on the flat surface of the fixing ring facing the convex portion of the plastic pipe joint portion located at the innermost side not facing the tapered surface of the fixing ring. Effect of the Invention

[0021] According to the invention described in claim 1, a wedge-shaped groove is formed on the inner circumference of the fixing ring, and when the fixing ring is pressed onto the outside of the plastic pipe, a portion of the resin material on the outer circumference of the plastic pipe enters the groove and forms a wedge portion in the plastic pipe. This wedge portion engages with the groove in the fixing ring, and the wedge action can reliably fix the fixed position of the fixing ring which clamps and fixes the plastic pipe. Furthermore, since the radial depth of the groove is made greater than the amount of shrinkage of the radial apex of the wedge portion after shrinkage when the plastic pipe reaches its creep limit and shrinks to its maximum, the groove portion of the ring and the wedge portion remain engaged even when the plastic pipe has shrunk to its maximum and reached its creep limit, and the wedge does not come loose, and the wedge action of the wedge portion does not move the fixing ring from its specified fixed position, reliably preventing movement and detachment of the fixing ring.

[0022] The present invention is suitable for pipe fittings that are connected to valves, and even when the plastic pipe is prone to creep and reaches its creep limit, it is possible to maintain the fixing force of the plastic pipe fixed to the fitting while preventing the fixing ring from coming loose.

[0023] In the present invention, the ring's inner circumferential groove is provided at a depth that takes into account the state in which the plastic pipe reaches its creep limit. Therefore, compared to a case in which only the shrinkage of the plastic pipe is taken into consideration, even when the valve to which the plastic pipe is connected is used for a long period of time or under conditions of high load that make the plastic pipe more likely to creep, such as when the valve is subjected to repeated thermal cycles or stress is applied to the plastic pipe connection part, the ring can be reliably prevented from moving from its fixed position on the plastic pipe without reducing the fixing force of the plastic pipe.

[0024] According to the invention described in claim 2, the cross-sectional shape of the groove is wedge-shaped, inverted V-shaped, or triangular, so that the resin material easily enters the groove when the ring is pressed in, and a wedge portion is easily formed. The wedge-shaped, inverted V-shaped, or triangular wedge portion formed by filling the resin material easily gets caught in the groove on the inner circumference of the ring, and easily exerts a wedge action to prevent the ring from moving or coming off the resin pipe.

[0025] According to the invention of claim 3 or 4, if the ratio of the volume of the resin material in the region where the inner circumference of the ring intersects with the outer circumference of the resin pipe and that is pushed out by pressing the ring into the resin pipe to the sum of the volume of the filling space and the volume of the recesses of the resin pipe connection part is 1.0 or less, the resin material of the resin pipe can be at least maximally accommodated in terms of volume, so that the resin material can be reliably filled into each recess while reliably preventing the resin material from spilling out. Also, if the ratio is 0.8 or more, it is preferable because there is no risk of insufficient filling due to the excessive volume that can accommodate the deformation of the resin pipe being secured, which would lead to voids that are not filled with resin.

[0026] According to the invention described in claim 5, the first convex portion is provided at the innermost portion in a position facing the tapered surface of the fixing ring, and the concave portion of the connection portion at the innermost portion is located forward of the innermost portion of the tapered surface where the resin material of the resin tube is difficult to fill, making it easier to fill each concave portion with the resin material. Furthermore, by providing a groove on the inner circumference of the ring at a position that does not overlap with the tapered surface of the inner circumference of the ring and faces the innermost convex portion, it is possible to sufficiently fill the resin material into the inner circumference groove portion of the ring while preventing the resin tube from breaking. [Brief description of the drawings]

[0027] [Figure 1] FIG. 2 is a partially cutaway vertical cross-sectional view of the valve with a plastic pipe joint of the present embodiment. [Diagram 2] 2 is a cross-sectional view of the plastic pipe joint in which the joint portion is separated from the valve body of the plastic pipe joint-equipped valve of FIG. 1. FIG. [Diagram 3] 4 is a diagram for explaining a state in which a fixing ring is fixed to a joint portion in the joint for plastic pipes of this embodiment. [Figure 4] 4 is a diagram showing a schematic diagram of the plastic pipe joint of the present embodiment in a state where the plastic pipe is maximally contracted. [Diagram 5] FIG. 1 is an explanatory diagram showing a schematic diagram of the procedure for inserting a plastic pipe and pressing in a ring into the plastic pipe joint of this example, where (a) shows the state in the middle of inserting the plastic pipe, (b) shows the state after the insertion of the plastic pipe has been completed, and (c) shows the state in the middle of pressing in the ring. [Figure 6] FIG. 4 is a cross-sectional view of another example of a valve with a plastic pipe joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment (present example) of the present invention will be described in detail with reference to the drawings. Fig. 1 is a partially cutaway vertical cross-sectional view showing a valve with a plastic pipe joint 1 of the present invention in a fully closed state. As shown in the figure, this example is a gate valve in which a valve body is opened and closed by manually rotating a round handle.

[0029] The present invention can be used not only for gate valves but also for various manual and automatic valves such as ball valves, globe valves, check valves, butterfly valves, and diaphragm valves. Furthermore, the present invention can be used not only for valves but also for various joint structures for connecting a resin pipe to an object, such as male-female thread sockets and couplers, as appropriate for the implementation.

[0030] As shown in Fig. 1, the valve body 2 of this example is a valve with a plastic pipe fitting 1, which comprises a body portion 3 and a fitting portion 4, and in which a plastic pipe 5 is fixed to the fitting portion 4 via a fixing ring 6 (hereinafter sometimes referred to as "ring"). A disc 7 (valve body) is housed within the body portion 3 so as to be movable up and down in a direction intersecting the axial direction of the flow passage, and a bonnet 8 having a mounting portion is connected to the upper portion of the body portion 3.

[0031] 1, a stem 9 is housed within the bonnet 8 concentrically with its axis, and a female thread 8a is provided on a portion of the inner peripheral surface of the bonnet 8, with a male thread 9a of the stem 9 screwed into the female thread 8a. A flange-shaped engagement portion that engages with the disk 7 is provided at the lower end of the stem 9, and a round handle 11 is fixed concentrically and rotatably with the stem 9 at the upper end of the stem 9 by tightening a hexagonal nut 10. A packing nut 14 that tightens a packing 13 via a gland 12 is screwed onto the upper end of the mounting portion of the bonnet 8, and the inside and outside of the mounting portion are sealed by tightening the packing nut 14.

[0032] 1, in the valve 1 with plastic pipe fitting of this example, by manually rotating the round handle 11, the stem 9 moves up and down within the range of the valve stroke in response to the screwing between the male thread 9a and the female thread 8a while the sealing of the mounting portion is maintained by the packing 13. In response to this movement, the disc 7 engaged at the engagement portion at the lower end of the stem 9 also moves up and down within the body portion 3, and the movement of this disc 7 closes or opens the flow path, opening and closing the valve.

[0033] A female thread 3a is formed in the body 3, and a joint 4 for connecting a plastic pipe can be connected to the female thread 3a. A hexagonal nut 15 is also formed in the body 3, and a jig can be engaged when the joint 4 is attached, when the plastic pipe 5 is inserted, or when the ring 6 is press-fitted.

[0034] In this example, the body 3 and the joint 4 are provided separately in the valve main body 2, and are configured to be detachable from the body 3. The joint 4 has a resin pipe connection portion 41 that can be connected to a resin pipe 5, and a male thread portion 43 is provided on the opposite side across the flange portion 42. This male thread portion 43 is screwed into the female thread portion 3a of the body 3, and the body 3 and the joint portion 4 are connected so as to be integrated. The flange 42 of the joint 4 has an outer periphery with a two-face width 44 that can be engaged with a jig for attaching the joint 4 to the valve body 2. This two-face width 44 can also be engaged with a jig used when press-fitting the fixing ring 6 after inserting the plastic pipe 5. Instead of the two-face width, the outer periphery of the flange 42 may be shaped like a hexagonal nut.

[0035] In this example, the joint portion and the body portion are formed separately, but as shown in Fig. 6, the joint portion 4 may be formed integrally with the body portion 3 to form a valve body, and the structure of the joint for plastic pipes of the present invention may be selected as desired depending on the implementation as long as it has at least the function of a joint structure. Note that a structure equipped with the joint portion of the present invention is referred to as a joint for plastic pipes.

[0036] The plastic pipe joint will be described in detail below with reference to Figures 2, 3, and 4. Figure 2 is a cross-sectional view of the plastic pipe joint with the joint portion 4 separated from the valve body 2 of the valve with plastic pipe joint 1 of this example in Figure 1. Figure 3 is a diagram for explaining the state in which the fixing ring 6 is fixed to the joint portion 4 in the plastic pipe joint of this example. Figure 4 is a diagram that diagrammatically shows the state in which the plastic pipe is maximally contracted in the plastic pipe joint of this example. Hereinafter, the side of the plastic pipe joint that connects with the body 3 of the valve body 2 (the valve body side or the joint body side) will be referred to as the back side, and the opposite side (the tip side) will be referred to as the front side.

[0037] 2 and 3, the joint 4 has a resin pipe connecting part (connecting part) 41 extending toward the tip side (axial direction), and the outer periphery of the connecting part 41 is uneven, and an inclined surface 46 tapering in diameter toward the front side is formed on the tip side of the connecting part 41. The inclination angle of the inclined surface 46 with respect to the axial direction of the joint (axial direction in FIG. 2) is preferably in the range of 15 to 30 degrees because this makes it easy to insert the resin pipe 5.

[0038] The unevenness of the connection part 41 is such that a plurality of convex parts (21, 22, 23, 24) and concave parts (26, 27, 28, 29) are arranged in an uneven manner, and all of the concave and convex parts are provided in an annular shape on the outer circumferential surface in a direction intersecting with the axial direction of the connection part. In this example, the cross-sectional shapes of all the concave parts (convex parts) are provided to be approximately the same, but the length and diameter of the connection part and the number and cross-sectional shape of the concave and convex parts are not limited to the structure of this example and can be arbitrarily selected depending on the implementation. Hereinafter, the convex part 21 may be referred to as the first convex part, and the convex part 22 may be referred to as the second convex part, etc.

[0039] As shown in FIGS. 3 and 4, each of the protrusions (21, 22, 23, 24) has a substantially trapezoidal cross-sectional shape and a flat upper surface. Each protrusion has an inclined surface that slopes toward the recess on the near side, and each of these inclined surfaces (21a, 22a, 23a, 24a) functions as a guide when inserting the resin pipe 5. When the ring 6 is pressed in, it can promote the resin material to enter each recess. The inclination angle of all or part of these inclined surfaces can be set within a range that provides such a function. Note that each inclined surface does not necessarily need to reach each recess, but in order to effectively provide the above function, it is preferable that each inclined surface reach the bottom of each recess.

[0040] 3, a convex portion (first convex portion) 21 is provided on the innermost side (innermost portion) of boundary portion 30 between engagement surface 45 of flange portion 42 and connection portion 41. The width and height of the upper surface portion of this convex portion 21 are the same as the width and height of the upper surface portions of the other convex portions. In this way, by providing the convex portion 21 at the innermost portion in a position opposite the tapered surface 62 of the fixing ring 6 described later, the concave portion 29 of the connection portion 41 at the innermost portion is positioned closer to the innermost portion of the tapered surface 62, where the resin material of the resin tube 5 is less likely to be filled, making it easier to fill the resin material into each concave portion (26, 27, 28, 29).

[0041] The resin pipe 5 connected to the joint 4 is a pipe body made of synthetic resin and capable of compressive deformation. For example, it can be applied to a polyethylene water pipe made of a relatively large diameter hard material, but it may also be a resin pipe made of other synthetic resins. When inserting the plastic pipe 5 into the connection portion 41 , the plastic pipe 5 is inserted to the innermost portion so that the tip surface 51 of the plastic pipe 5 abuts against the engagement surface 45 of the flange portion 42 of the joint portion 4 .

[0042] When inserting the plastic pipe 5 into the connection portion 41, a fixing ring 6 is provided on the plastic pipe 5 in advance, and after the plastic pipe 5 has been inserted into the connection portion 41, the fixing ring 6 tightly fixes the plastic pipe 5 to the connection portion 41, thereby completely fixing the plastic pipe 5 to the joint portion 4.

[0043] Furthermore, when the ring 6 is press-fitted into the plastic pipe 5, a part of the outside of the plastic pipe 5 enters the groove 61 of the ring 6, and a wedge portion 52 is integrally formed on the outer periphery of the plastic pipe 5. This wedge portion 52 engages with the groove 61 of the ring 6, and exerts a wedge action, which will be described later, and the ring 6 can be fixed at a predetermined fixed position.

[0044] The fixing ring 6 is an annular fastening member having a predetermined thickness and formed integrally from metal. As shown in Fig. 2, a wedge-shaped groove 61 is provided on the inner peripheral surface of the fixing ring 6, one end surface of which is an insertion end 63 that abuts against the engagement surface 45 of the flange 42, and a tapered surface 62 is formed on the inner peripheral surface of the insertion end 63, the diameter of which increases toward the back side. A tapered surface 64 of a similar shape may be formed on the opposite side of the tapered surface 62. These tapered surfaces are inclined at a predetermined angle (for example, about 15 to 30 degrees).

[0045] Furthermore, if the tapered surface 62 of the ring 6 has a certain degree of surface roughness, it is possible to improve the pull-out resistance of the plastic pipe 5 to the joint portion 4. Furthermore, if the boundary 62a of the tapered surface 62 and the boundary with the insertion end 63 have a rounded shape, this is preferable because it makes it difficult for damage to occur to the plastic pipe 5 and makes it easier to prevent breakage, etc. of the plastic pipe 5 in the fixed state.

[0046] The inner diameter of the fixing ring 6 is set smaller than the outer diameter of the resin pipe 5, and before being fixed, the ring 6 is arranged in advance in a loosely fitted state in the resin pipe 5 and is then pressed into the resin pipe 5 and fixed. As shown in FIG. 3, the inner diameter φd2 of the ring 6 is set so that the total volume of the recess of the resin pipe connection portion 41 and the filling space described later satisfy a predetermined relationship with the compressed volume of the resin material of the compressed resin pipe 5.

[0047] The groove 61 provided on the flat surface 65 of the ring 6 has a cross-sectional shape that is wedge-shaped, V-shaped, or triangular. The groove 61 is preferably provided in a position facing a protrusion that does not face a tapered surface 62 that expands in diameter toward the valve body side (joint body side), and in the vicinity of the tapered surface 62 of the ring 6.

[0048] That is, as shown in Figures 3 and 4, when pressed into the plastic pipe 5 and fixed, this groove portion 61 is positioned to face the adjacent protrusion 22 (second protrusion) located on the front side of the protrusion 21 (first protrusion) located at the innermost side of the plastic pipe connection portion 41. If the groove portion 62 is located at a position facing the protrusion of the resin pipe connecting portion 42, the resin material of the resin pipe can be easily pressed into the groove portion 62 when the ring 6 is press-fitted.

[0049] When the ring 6 is pressed onto the outside of the plastic pipe 5, a part of the outside of the plastic pipe 5 enters the groove portion 61 and a wedge portion 52 is formed on the outer peripheral surface of the plastic pipe 5. This wedge portion 52 is engaged within the groove portion 61, thereby holding the ring 6 in a predetermined fixed position.

[0050] In addition, since the cross-sectional shape of groove 61 is wedge-shaped, V-shaped, or triangular, the resin material easily enters groove 61 when the ring is pressed in, and a wedge portion is easily formed. The wedge portion formed by filling the resin material easily becomes caught in the groove portion on the inner circumference of the ring, and easily exerts a wedge action to prevent the ring from moving or coming off the resin pipe. For this reason, the cross-sectional shape is preferably a wedge shape, a V shape, or a triangle shape, but other shapes are also acceptable as long as the wedge portion 52 can be formed. As other shapes, for example, the cross-sectional shape may be a U-shape, a C-shape, an arc shape, a U-shape, etc. Also, a plurality of grooves may be provided on the inner circumference of the ring. However, from the viewpoint of filling the recess of the resin pipe connection portion with a large amount of resin material, it is preferable that the number of grooves is small.

[0051] The groove 61 does not necessarily have to be provided at the back side, but is preferably provided on the flat surface 65 at the back side of the ring 6. If the groove on the inner circumference of the ring is too close to the end side where the resin pipe 5 is inserted, the resin material on the tip end surface 51 side of the resin pipe fills the tapered surface 62 and the bamboo shoot groove (recess) before filling the groove, which may result in insufficient filling of the resin material in the groove and insufficient effect of preventing the ring from coming off. Therefore, by providing a groove on the inner circumference of the ring 6 at a position opposite the innermost convex portion but not overlapping with the tapered surface 62 on the inner circumference of the ring 6, it is possible to sufficiently fill the resin material into the inner circumference groove of the ring while preventing the resin tube from breaking.

[0052] 4, the axial width a of the groove 61 is within the axial width b of the opposing protrusion 22 and is smaller than the axial width b of the protrusion 22. To make it easier to push the resin material into the groove 61 by the opposing protrusion, it is more preferable that a be equal to or less than half the width b.

[0053] Further, the depth c of the groove 61 is set to a minimum depth at which the ring 6 does not move from the fixed position even if the resin pipe 5 reaches the limit of the creep state. Here, "the ring 6 will not move from its fixed position even when the plastic pipe 5 reaches its creep limit" means that even when the plastic pipe 5 is subjected to repeated stress, etc., reaches its creep limit, and experiences maximum shrinkage, the ring 6 will not move from its initial fixed position. The maximum shrinkage is the maximum shrinkage expected in actual use of the plastic pipe 5, and mainly refers to thermal shrinkage that may occur at the expected operating temperature of the plastic pipe 5. That is, as shown in FIG. 4, the radial depth c of the groove portion 61 is greater than the amount of shrinkage cd of the radial top of the wedge portion 52 after shrinkage when the resin pipe 5 has shrunk to the maximum.

[0054] In this way, even if the plastic pipe 5 shrinks, the depth of the groove portion 61 is set to a depth that maintains the engagement between the wedge portion 52 and the groove portion 61 and maintains the wedge action without the wedge coming off, thereby fixing the position of the fixing ring and preventing the ring from coming off the plastic pipe.

[0055] In addition, the positional relationship between the groove 61 of the ring 6 and the convex portion 22 facing the groove 61 is preferably such that at least the top (deepest part) of the groove 61 is located within the width b of the convex portion 22. This allows the resin material of the resin tube 5 to be reliably filled up to the top of the groove 61. The width a of the groove 61 is preferably provided within the width of the convex portion 22 and the inclined surface 22a on the front side thereof. The width a of the groove 61 may extend beyond the width b of the convex portion 22, but in this case, if the width a of the groove 61 extends to the front side, the resin material pushed by the upper surface of the convex portion 22 when the ring 6 is pressed in is more easily filled into the groove 61.

[0056] After connection, the plastic pipe will creep when used for a long period of time and subjected to temperature changes and various stresses. However, by providing a groove at a specified position, the fixing ring can be prevented from coming loose. In this case, the depth of the groove is important, but the test results described below have shown that the shrinkage of the plastic pipe when creep reaches its limit is not greatly affected by the diameter of the plastic pipe and is within a certain range. Therefore, by taking into account the amount of shrinkage when creep reaches its limit depending on the material of each type of plastic pipe, and providing a groove deeper than the maximum amount of shrinkage, it is possible to reliably prevent the ring from falling off. On the other hand, if the groove size is too large, the resin pipe material filling the resin pipe connection part will escape, so the depth of the groove of the ring in the present invention should be within 5 times the maximum shrinkage of the resin pipe when creep reaches its limit. From the viewpoint of reliably preventing the ring from coming off and minimizing the depth of the groove, it is preferably within 3 times, more preferably within 2 times.

[0057] Here, the valve is a pressure vessel that is placed between flow paths to allow, stop, and control the flow of fluid in the flow paths, and is affected by the pressure and temperature of the fluid at the parts that come into contact with the fluid. For this reason, pressure and temperature changes are likely to occur before and after the valve switches between opening and closing, and the joints that connect to the valves tend to be easily affected by pressure and temperature changes, so creep is likely to occur in the plastic pipes connected to the joints.

[0058] Therefore, when the plastic pipe of a plastic pipe joint shrinks due to pressure fluctuations or temperature changes, the plastic pipe creeps over a long period of use and when it reaches its limit, it loses its elasticity.

[0059] If the plastic pipe has not yet reached its creep limit, even if it shrinks to a certain extent, its elastic force will be able to hold the ring in a fixed position. However, if the plastic pipe has reached its creep limit, it will no longer be able to exert an elastic force toward the ring, and so the effect of preventing the ring from moving will be significantly reduced. If it is not possible to reliably prevent the ring from coming loose, the fixing force that fixes the plastic pipe to the joint will decrease, and there is a risk that the plastic pipe will come loose from the joint.

[0060] With conventional joint structures, there was a risk that it would not be possible to reliably prevent the fixing ring from coming off the plastic pipe when the plastic pipe had shrunk to its maximum and reached its creep limit. If the ring could not be prevented from coming off when the plastic pipe had reached its creep limit, the fixing ring would loosen or rattle, not only reducing the fixing force (fastening force) of the fixing ring, but also reducing the fixing force securing the plastic pipe to the joint, which could cause the plastic pipe to come off the joint.

[0061] In the present invention, taking into consideration the state in which the plastic pipe has reached its creep limit, the depth is set to the minimum value that can reliably prevent the ring from coming off the plastic pipe and maintain the fixing force that fixes the plastic pipe to the joint, even when the plastic pipe has shrunk to its maximum. For this reason, it is suitable even when the plastic pipe shrinks and reaches its creep limit, making it susceptible to maximum shrinkage, and is particularly suitable for use as a plastic pipe joint for connection to a valve. Furthermore, since the depth of groove portion 61 is kept to a minimum, it is possible to reliably prevent the ring from coming off the resin pipe without affecting the filling of the resin material into the recess of resin pipe connection portion 41 (described later), while increasing the adhesion between the inner surface of resin pipe 5 and the outer surface of resin pipe connection portion 41.

[0062] Next, the relationship between the compressed volume of the resin pipe compressed by the ring 6 and the total volume of the recess of the resin pipe connecting portion 41 and the filling space will be described. The compressed volume of the resin pipe compressed by the inner circumference of the ring is set to be equal to or smaller than the sum of the volume of the recess of the resin pipe connection portion 41 and the volume of the filling space formed by the tapered surface 62 and the engagement surface 45 into which the resin pipe is filled.

[0063] In FIG. 3, the inner side surfaces of the recesses 26, 27, 28, 29 are tapered inclined surfaces 21a, 22a, 23a, 24a whose outer periphery is inclined toward the inner side, and the inclination angle of these surfaces is an angle θ1 (for example, about 60 degrees) with respect to the axial direction of the joint part 2 (horizontal direction in FIG. 3). On the other hand, the outer side surfaces facing these inclined surfaces 21a, 22a, 23a, 24a are vertical surfaces facing in a direction intersecting the axial direction of the joint part 4. Also, as shown by the dashed lines in the figure, the volumes of the annular spatial regions in the recesses 26, 27, 28, 29 are indicated by A1, A2, A3, A4, respectively. Also, the width (horizontal length in FIG. 3) of the cylindrical bottom surface portion of each recess is indicated by m, the diameter of each bottom surface portion is indicated by φd1, and the value obtained by adding m to the width (horizontal length in FIG. 3) of each inclined surface 21a, 22a, 23a, 24a is indicated by n. In this example, n is referred to as the width of the recess. Furthermore, if the diameter of the cylindrical upper surface of each of the protrusions 21, 22, 23, 24, and 25 is φD1 and the height of each protrusion is h, the height h of the protrusion is approximately equal to φD1-φd1. φD1 is also equal to the outer diameter of the resin pipe connection portion 41.

[0064] The angle θ2 is preferably in the range of 15 to 30 degrees. If this angle is too small, the plastic pipe 5 is easier to insert but may easily come off, whereas if the angle is too large, stress is applied to the plastic pipe 5 during insertion, making it difficult to insert. It is preferable that the angle θ2 is approximately the same as the angle θ3 of the inclined surface 46 of the plastic pipe connecting portion 41, since this makes it easier to insert the plastic pipe 5.

[0065] In addition, in the same figure, the inner diameter of the ring 6 is shown as φd2, the diameter of the outer boundary portion between the tapered surface 62 and the insertion end 63 is shown as φD3, and the distance (horizontal length in the same figure) between the position of the boundary portion between the opposite tapered surface 64 and the cylindrical inner surface and the position of the insertion end 63 is shown as L2.

[0066] In Fig. 3, when the insertion end 63 of the ring 6 abuts against the engagement surface 45 and the fixing of the plastic pipe 5 is completed, an annular space having a substantially triangular cross section shown as A5 in the figure is formed as an area surrounded by the tapered surface 62, the engagement surface 45, and the outer peripheral surface of the plastic pipe 5 shown imaginarily by a two-dot chain line. This spatial area is called the filling space. This filling space is a space into which the plastic material of the plastic pipe 5 that has been compressed and deformed by the press-fitting of the ring 6 escapes. In addition, by abutting the insertion end 63 of the ring 6 against the engagement surface 45 in this manner, it is possible to accurately determine the positional relationship between the convex portion of the resin pipe connection portion 41 and the groove portion 61 on the inner circumference of the ring 6, which is advantageous for filling the resin material into the groove portion 61. In this example, it is preferable to take into account the resin material that enters the groove 61 on the inner circumference of the ring 6 when calculating the total volume of the filling space; however, since this groove is of a "minimum depth," even if it is not taken into account, the effects of both the fixing force of the resin tube and the prevention of the ring falling out due to the groove are fully exerted, so in this example, it is not a problem if it is not included in the total volume of the filling space.

[0067] In FIG. 3, the annular space region indicated by cross-hatching virtually indicates the region where the inner circumference of the ring 6 and the resin pipe 5 intersect.

[0068] That is, when the resin pipe 5 is fitted into the outer periphery of the joint part 4 while expanding its diameter without changing its thickness, if we imagine a state in which the inner periphery of the ring 6 at the press-fit completion position is overlapped with the outer periphery of the resin pipe 5 in this state, an intersection region is generated between the inner periphery of the ring 6 and the outer periphery of the resin pipe 5. The annular space region shown by cross-hatching in the figure indicates this intersection region. Also, the thickness of the resin pipe 5 is generally equal to φD2-φD1 in the figure.

[0069] Incidentally, the area into which the resin material can escape by such extrusion is the volume of all the recesses 26-29 and the volume of the filling space in this example, if deformation and escape of the resin material toward the outside of the area compressed by the ring 6 are not taken into consideration. Therefore, if the total volume of all the recesses 26-29 and the volume of the filling space is equal to or smaller than the volume of the intersection area, the escape volume of the resin material due to compression deformation can be accommodated at the maximum. Therefore, the compressed and deformed resin material will not protrude from the back side of the ring 6, i.e., between the insertion end 63 and the engagement surface 45, as the ring 6 is pressed in, unless the resin expands.

[0070] Meanwhile, A1 to A4 are the volumes inside the recesses 26 to 29, respectively, and A5 is the volume of the filling space. Also, A6 is the volume of the extruded resin material, and is approximately equal to the volume of the intersection region, so if A6 is equal to or smaller than the sum of A1 to A5 (1.0 or less), it can accommodate at least the maximum volumetric amount of the compressive deformation of the resin material of the resin tube 5, so that the resin material can be reliably filled into each of the recesses 26 to 29 while reliably preventing the resin material from spilling out.

[0071] On the other hand, if the volume that can tolerate the deformation of the resin pipe 5 is secured excessively, there is a risk that voids that are not filled with resin will be generated and the filling will be insufficient, so it is preferable to set an appropriate lower limit value for this ratio. However, even if this lower limit value is too close to 1.0, it may be insufficient as a volume that can tolerate the deformation of the resin. For example, when a hard resin is subjected to a biased compression deformation, it is possible that deformation that exceeds the allowable volume will occur in parts, causing the resin to overflow, etc. In addition, it is preferable to set a lower limit value that can be tolerated to a certain extent in common for different resin materials depending on the type of the resin pipe 5. For example, 0.8 can be given as such a lower limit value. To summarize the above, the following relationship is obtained.

[0072]

number

[0073] However, the resin material may actually be compressed to some extent in volume by pressing the ring 6. In this case, the volume A6 of the resin material actually pushed out by pressing the ring 6 is smaller than the volume of the intersection region shown in FIG.

[0074] Although not shown, the present invention can be applied to general joints, plastic pipes, and rings, not limited to the structure of this example. When imagining a ring at a position where press-fitting is completed for a plastic pipe in a state where insertion is completed into a joint, an intersection area occurs between the inner circumference of the ring and the outer circumference of the plastic pipe. The volume V1 of this intersection area is approximately equal to the volume of the resin material extruded into the ring. In addition, in this imaginary state, if the sum of the volumes of the gaps between the inner circumference of the ring and the outer circumference of the plastic pipe is V2, and the sum of the volumes of the gaps between the outer circumference of the joint and the inner circumference of the plastic pipe is V3, if at least V2+V3>V1, the resin material can be reliably filled into each recess while preventing the resin material from overflowing in a volumetric structure.

[0075] 3, in this example, the convex portion 21 disposed in the boundary portion 30 is set to a height h that is approximately the same as the convex portion 22 located one outside of it, but for example, the height of this convex portion 22 may be slightly lower than h. In this case, for example, even if the tip surface 51 of the plastic pipe 5 is not expanded in diameter when it is fully inserted into the joint portion 4, the tip surface 51 can reliably reach the engagement surface 45 without being caught by the convex portion 21. In addition, in this insertion complete state, a small gap can be secured between the inner circumference near the tip surface 51 and the upper surface of the convex portion 21, so that a space is secured for the resin to escape to as it is compressed and deformed, and the extrusion of the resin material is more reliably prevented. This prevents the resin material of the resin pipe from popping out after the fixing ring is press-fitted into the resin pipe and fixed, improving the appearance after the resin pipe is completely installed.

[0076] Next, we will explain the valve with a plastic pipe joint and the method for fixing a plastic pipe to the connection part of the plastic pipe joint in the present invention, and the function of the plastic pipe joint of the present invention. Figure 5 is an explanatory diagram that shows the procedure for inserting a plastic pipe and pressing a ring into the plastic pipe joint of this example, where (a) shows the state in the middle of inserting the plastic pipe, (b) shows the state after the insertion of the plastic pipe is completed, and (c) shows the state in the middle of pressing the ring.

[0077] 5(a), the inner circumference of the plastic pipe 5 is brought close to the connecting portion 41 so as to be fitted therein, and the plastic pipe 5 is inserted into the connecting portion 41 while expanding its diameter. When the plastic pipe 5 is inserted toward the axial back side of the connecting portion 41, the inclined surface 46 slides onto the inner circumference surface of the plastic pipe 5 while expanding the diameter of the plastic pipe 5. The inner diameter of the plastic pipe 5 is smaller than the outer diameter of the connecting portion 41 by a specified percentage, and the inclined surface 46 protrudes toward the front side, so that the inside of the tip surface 51 of the plastic pipe 5 can be easily covered all around while aligning it with the inclined surface 46, making it easy to insert the plastic pipe 5.

[0078] 5(b) shows a state where the tip surface 51 is in contact with the engagement surface 45 of the flange 42 evenly over the entire circumference and the insertion of the plastic pipe 5 is completed. In this state, the upper surface of the innermost protrusion 21 (first protrusion) is evenly covered over the entire circumference of the tip surface 51 of the plastic pipe 5.

[0079] 5(c) shows the state in the middle of pressing the ring in. The ring 6 is pressed into the plastic pipe 5 that has been completely inserted into the connection part 41, and the plastic pipe 5 is completely fixed to the joint part 4, completing the connection of the plastic pipe 5.

[0080] After the resin pipe 5 is completely inserted, the tapered surface 62 of the ring 6 is brought closer to the engagement surface 45, and the tapered surface 62 is positioned up to the upper surface of the resin pipe 5 which is fitted into the connection part 41 and expanded in diameter, and the fixing ring 6 is pressed in. Here, the tapered surface 62 matches the shape of the outer periphery of the resin pipe 5, which similarly expands in diameter in a tapered manner, so the ring 6 can be press-fitted while being aligned evenly around the entire circumference of the tapered surface 62. When the insertion end 63 of the ring 6 is brought into contact with the engagement surface 45 evenly around the entire circumference, the press-fitting of the ring 6 is completed.

[0081] When the ring 6 is pressed into the plastic pipe 5, the inner flat surface 65 of the ring 6 compresses the outer surface of the plastic pipe 5, so that the inner surface of the plastic pipe 5 and the outer surface of the connection part 41 come into close contact with each other, and the resin material on the inner surface of the plastic pipe 5 is forced into the recesses of the connection part 41, filling all of the recesses of the connection part with the resin material. Furthermore, on the outer peripheral surface of the resin pipe 5 , compression by the ring causes the resin material to enter part of the outer periphery of the resin pipe 5 into the groove portion 61 , and a wedge portion 52 is integrally formed on the outer periphery of the resin pipe 5 .

[0082] That is, in the process of pressing the ring 6 into the plastic pipe 5, a volume of the plastic material of the plastic pipe that comes into contact with the flat surface 65 is pushed out by compression deformation and fills the recess of the connection part 41, and a part of the plastic material escapes into the filling space at the back side and fills the filling space. Meanwhile, a wedge part 52 is integrally formed on the outer circumferential surface of the plastic pipe.

[0083] Here, if there is no compression or expansion of the resin material, the volume of the extruded resin material will be such that the resin material of the resin pipe 5 escapes into the recess or the filling space and fills a specified volume, and as a result of this filling of the resin material, the resin pipe 5 becomes fixed to the connection part 41, providing sealing properties and resistance to withdrawal.

[0084] Since the innermost convex portion 21 (first convex portion) is located at the boundary portion 30 between the engagement surface 45 and the connection portion 41, it is possible to fill all of the concave portions of the connection portion 41 with resin material, compared to when the innermost portion is a concave portion. If the innermost region is sufficiently filled with resin material, the adhesive strength to the engagement surface 45 is also good, and the resin pipe 5 can be given high pull-out resistance and sealing properties.

[0085] Furthermore, since a groove 61 is provided on the inner circumference of the fixing ring 6, when the fixing ring 6 has been press-fitted into the plastic pipe 5, a wedge portion 52 formed on the outer circumference of the plastic pipe 5 engages with the groove on the inner circumference of the ring 6, and the wedge portion 52 exerts a wedge action against the movement of the ring 6 fixed to the plastic pipe 5. In other words, when a moving force acts on the ring 6 fixed to the plastic pipe 5, the wedge portion 52 becomes a stopper and acts to restrain the movement of the ring 6. Therefore, the wedge action of the wedge portion 52 prevents the fixing ring 6 from moving or coming off, and allows the fixing ring 6 to be held in the initial fixed position.

[0086] In addition, the depth of the groove 61 is set to a minimum depth that prevents the fixing ring 6 from moving from the fixed position even if the plastic pipe 5 reaches the limit of the creep state. Therefore, even if the plastic pipe 5 reaches the limit of the creep state and shrinks to the maximum, the fixing ring 6 will not come off the plastic pipe 5, and the fixing ring 6 can be kept in the initial fixed position. That is, as shown in FIG. 4, the radial depth c of groove portion 61 is greater than the amount of shrinkage cd of the radial apex of wedge portion 52 when plastic pipe 5 shrinks. Therefore, even when plastic pipe 5 has shrunk to its maximum, the groove portion 61 of ring 6 and wedge portion 52 remain engaged with each other, and the wedge action of wedge portion 52 reliably prevents the fixing ring from moving or coming off, without the wedge coming loose, and the fixing ring 6 can be held in its original fixed position.

[0087] Furthermore, the groove 61 on the inner circumference of the ring 6 is of a minimum depth that will prevent the fixing ring 6 from moving from its fixed position even when the plastic pipe 5 reaches its creep limit. Therefore, there is no need to make the groove 61 excessively deep to prevent the ring 6 from coming off, and the amount of resin material that enters the groove 61 is minimal. This allows the resin material to be sufficiently filled into the recess of the bamboo shoot groove, maintaining good adhesion between the inner surface of the plastic pipe 5 and the outer surface of the plastic pipe connection part 41, and making it easier to maintain the fixing force that fixes the plastic pipe 5 to the joint part 4 even when the plastic pipe 5 shrinks to its maximum.

[0088] Therefore, the present invention can maintain the fixing force fixing the plastic pipe 5 to the joint portion 4 while reliably preventing the ring 6 from coming off the plastic pipe 5 even when the plastic pipe 5 reaches its creep limit, thereby improving pull-out resistance and maintaining good sealing performance.

[0089] Furthermore, when the fixing ring 6 has been press-fitted into the resin pipe 5, the groove 61 of the fixing ring 6 faces a protrusion that does not face the tapered surface 62. That is, as shown in Figures 3 and 4, when the fixing ring 6 has been press-fitted into the resin pipe 5, the groove 61 of the ring 6 is located in a position facing the protrusion 22 (second protrusion) on the near side adjacent to the protrusion 21 (first protrusion) at the innermost part of the resin pipe connection part 41. As a result, the second convex portion 22 pushes the resin material outward, ensuring that the resin material of the resin pipe 5 is filled up to the top (deepest part) of the groove portion 61, thereby forming a wedge portion 52 on the outer peripheral surface of the resin pipe 5. Moreover, only a minimum amount of resin material is required to form the wedge portion 52, and a sufficient amount of resin material can be secured to fill the recess of the resin pipe connection portion 41, thereby maintaining the fixing force that fixes the resin pipe 5 to the joint portion 4 without reducing the adhesion between the inner surface of the resin pipe 5 and the outer surface of the connection portion 41.

[0090] Furthermore, since the groove 61 is provided not on the tapered surface 62 but on the flat surface 65 on the inner periphery of the ring 6 near the tapered surface 62, the resin pipe 5 is unlikely to be damaged when the ring 6 is press-fitted. Here, when the ring 6 is pressed in, the resin material on the outer peripheral surface of the resin pipe 5 fills the tapered surface 62, and the outer peripheral side of the resin pipe 5 bends along the taper 62 side, but the strength of the area near this bent portion tends to be inferior to other parts. If the groove portion 61 on the inner circumference of the ring 6 is too close to the tapered surface 62, the convex portion of the bamboo shoot groove will inevitably face this weaker portion, and the corners of this convex portion will act on the weaker portion of the plastic pipe 5, which may become the starting point for the breakage of the plastic pipe 5. However, since the groove portion 61 is provided so as to face at least the second convex portion 22 which does not overlap with the tapered surface 62 of the ring 6, the convex portion of the bamboo shoot groove will not face a position close to the portion where the plastic pipe 5 is bent, making the plastic pipe 5 less likely to break.

[0091] In addition, since a tapered surface 62 is provided on the tip surface 63 side of the fixing ring 6, the resin material near the innermost region is pushed out and filled into the filling space, which is a gap, as the resin pipe 5 is compressed and deformed. The resin material of the compressed resin pipe is reliably filled into the specified filling region, and it is possible to prevent the resin material of the resin pipe from protruding from the fixing ring 6.

[0092] In addition, since groove 61 is provided on the back side of the ring, the resin material of the resin tube can be sufficiently filled in groove 61. If groove 61 of the ring were provided closer to the front side (tip side), the resin material on the back side would fill the tapered surface and the recesses of the bamboo shoot groove before being filled into groove 61, which may result in insufficient filling of the resin material in groove 61 and insufficient effect of preventing ring 6 from coming off. Therefore, by providing a groove on the inner circumference of the ring 6 at a position opposite the innermost convex portion 22 (second convex portion) and not overlapping with the tapered surface 62 on the inner circumference of the ring 6, it is possible to sufficiently fill the resin material into the inner circumference groove portion 61 of the ring 6 while also preventing the resin tube 5 from breaking. On the other hand, when the press-fitting direction of the ring 6 is fixed, there is a possibility that the worker may insert it in the wrong direction. If it is important to prevent such an inserting direction error, it is preferable that the groove 61 on the inner circumference of the ring 6 faces the central protrusion of the resin pipe connecting part 41.

[0093] Furthermore, when the heights of the multiple convex portions provided on the outer periphery of the resin pipe connection portion 41 are made the same, a sufficient amount of resin material can be secured to fill the concave portions of the resin pipe connection portion 41 while minimizing the amount of resin material of the resin pipe 5 pushed outward, and a large amount of resin material of the resin pipe 5 can be filled into the concave portions of the bamboo shoot groove of the resin pipe connection portion 41 when the ring 6 is pressed in, thereby increasing the adhesion between the resin pipe 5 and the resin pipe connection portion 41. Therefore, even if creep occurs in the plastic pipe of the plastic pipe joint connected to the valve and the plastic pipe shrinks to its maximum, the fixing force of the plastic pipe fixed to the joint portion can be maintained, preventing the plastic pipe from coming loose from the joint portion. In addition, when the fixing ring 6 is pressed into the resin tube 5, the stress applied to the resin tube 5 can be dispersed, which is effective in reducing deformation and bending of the resin tube 5 and preventing breakage of the resin tube when the ring is pressed into the resin tube.

[0094] Furthermore, if the cross-sectional shape of the groove 61 is wedge-shaped, V-shaped, or triangular, the resin material can easily enter the groove 61, and the wedge 52 can easily be formed integrally with the outer circumferential surface of the resin pipe. And, wedge portion 52 formed by filling with resin material becomes easily caught in groove portion 61 on the inner circumference of ring 6, so that wedge portion 52 is easily locked in groove portion 61 and can exert a wedge action on ring 6. Therefore, the pressed-in fixing ring 6 can be held in a predetermined fixed position.

[0095] In this way, with the present invention, even if the plastic pipe is used in an environment prone to creep and there is a possibility that the plastic pipe may reach its creep limit, the fixing ring that secures the plastic pipe inserted into the connection portion of the plastic pipe joint is reliably prevented from moving or coming off, making it possible to sufficiently maintain the fixing force that secures the plastic pipe to the joint portion.

[0096] Furthermore, the present invention can be applied regardless of the diameter of the valve, joint, or plastic pipe, and does not require complex processing or design, which also contributes to reducing costs.

[0097] Next, Fig. 6 is a cross-sectional view of another example of a valve with a joint for plastic pipes 100. In Fig. 6, except that the joint portion 4 is provided integrally with the valve body 2, it is the same as the valve with a joint for plastic pipes 1 described above, and the structure of the joint portion is also the same, so the same parts are given the same reference numerals and their explanation will be omitted.

[0098] 6, in this example, the joint 4 is integral with the valve body 2, and the joint 4 has a flow path formed within a plastic pipe connection part 41 that protrudes linearly from both side surfaces of the body 3. Because the joint 4 is integral with the body 3, a plastic pipe can be directly connected to the valve body 2 for use, without the need to prepare and attach a joint for a plastic pipe.

[0099] Although the valve with a joint for plastic pipe of the present invention has been described above, the same effects can be obtained when this joint structure is applied to a joint for plastic pipe. When the structure of the present invention is applied to a valve or joint, the size is not limited, but a size of 20A to 100A, for example, is particularly suitable.

[0100] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention as described in the claims of the present invention.

[0101] <Test Example> The plastic pipe joint of the present invention was tested. The test examples are not intended to limit the present invention. As an example, a polyethylene water supply pipe was tested to see how much the plastic pipe shrinks before and after a creep test. The creep test was carried out using polyethylene water supply pipes of various diameters, with the above-mentioned plastic pipe joint structure connected to both ends, and was held for 1000 hours under conditions of 80°C water temperature and 1.0 MPa internal pressure. These conditions are equivalent to 50 years of use at 20°C (ISO12162, PE100 test), which is the condition at which creep reaches its limit. Before and after the test, the outer diameter of the polyethylene pipe near the rings of the joint structure connected to both ends was measured, and the difference between these values ​​was regarded as the amount of shrinkage of the entire pipe, and half this value was regarded as the amount of shrinkage of the polyethylene pipe thickness.

[0102] [Table 1]

[0103] Table 1 shows the test results. From these results, it was found that the shrinkage of the thickness of a polyethylene water supply pipe is 0.05 to 0.10 mm. Therefore, if the depth of the groove 61 on the inner circumference of the fixing ring 6 is set to about 0.5 mm, for example, it is possible to prevent the ring from coming off even if the creep limit is reached and the plastic pipe shrinks to the maximum. [Explanation of symbols]

[0104] 1 Valve with resin pipe for resin pipe 2 Valve body 4 Joint 5 Plastic pipe 6 Fixing ring (ring) 21 Convex portion (first convex portion) 22 Convex portion (second convex portion) 41 Plastic pipe connection (connection) 45 Engagement surface 51 Tip surface 52 Wedge part 61 Groove 62 Tapered surface 63 Insertion end 65 Flat surface a Groove width b Width of second protrusion c Groove depth d Height of the top of the wedge when the plastic pipe shrinks

Claims

1. 1. A valve with a fitting for plastic pipes in which a fitting portion having a plastic pipe connection portion having an uneven outer circumference is provided integrally with or separately from a valve body, a plastic pipe is inserted into this plastic pipe connection portion, and a fixing ring is pressed into the outer circumference of the plastic pipe to fix the plastic pipe to the fitting portion, wherein a wedge-shaped groove is formed on the inner circumference of the fixing ring, and when the fixing ring is pressed into the outside of the plastic pipe, part of the plastic pipe enters into the groove to form a wedge portion in the plastic pipe, and this wedge portion is engaged in the groove,

2. 2. The valve with a joint for a plastic pipe according to claim 1, wherein a cross-sectional shape of the groove is a wedge shape, an inverted V shape or a triangle shape.

3. 3. The valve with plastic pipe fitting according to claim 1 or 2, wherein a tapered surface is provided on the valve body side of the fixing ring, the diameter of which increases towards the valve body side, and the ratio of the volume of the resin material in a region where an inner circumference of the ring and an outer circumference of the plastic pipe intersect and which is pushed out by pressing the ring into the plastic pipe, to the sum of the volume of a filling space provided by this tapered surface and an engagement surface of a flange portion provided on the outer circumference of the fitting portion and the total volume of the recessed portion of the plastic pipe connection portion is 0.8 or more and 1 or less.

4. A valve with a resin pipe fitting is provided with a fitting portion having a resin pipe connection portion with unevenness on the outer periphery, either integrally with or separately from a valve body, a resin pipe is inserted into this resin pipe connection portion, and a fixing ring is pressed into the outer periphery of the resin pipe to fix the resin pipe to the fitting portion, wherein a wedge-shaped groove is formed on the inner periphery of the fixing ring, and when the fixing ring is pressed into the outside of the resin pipe, a part of the resin pipe enters into the groove to form a wedge portion in the resin pipe, and this wedge portion is engaged in the groove. a valve with a fitting for a plastic pipe, characterized in that a tapered surface is provided on the valve body side of the fixing ring, the diameter of which increases towards the valve body side, and the ratio of the volume of the resin material in a region where the inner circumference of the ring and the outer circumference of the plastic pipe intersect, which is pushed out by pressing the ring into the plastic pipe, to the sum of the volume of a filling space provided by this tapered surface and an engagement surface of a flange portion provided on the outer circumference of the fitting portion and the total volume of a recess in the plastic pipe connection portion, is 0.8 or more and 1 or less.

5. 1. A valve with a plastic pipe fitting, in which a fitting portion including a plastic pipe connection portion having an uneven outer periphery and a flange portion with which the plastic pipe abuts is provided integrally with or separately from a valve body, a plastic pipe is inserted into this plastic pipe connection portion, and a fixing ring is pressed into the outer periphery of the plastic pipe to fix the plastic pipe to the fitting portion, wherein a wedge-shaped groove is formed on the inner periphery of the fixing ring, and when the fixing ring is pressed into the outside of the plastic pipe, part of the plastic pipe enters into the groove portion to form a wedge portion in the plastic pipe, and this wedge portion is engaged in the groove.

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