JP7788210B2 - Valves with fittings for plastic pipes and fittings for plastic pipes - Google Patents

Description

The present invention relates to a valve with a plastic pipe joint and a plastic pipe joint, and in particular to a valve with a plastic pipe joint and a plastic pipe joint that, after the plastic pipe is fixed to the joint by press-fitting the fixing ring, prevents the fixing ring from coming off and maintains the fixing force of the plastic pipe.

Conventionally, plastic pipe fittings have been known that have a so-called bamboo-shaped groove on the outer periphery of the metal fitting, in order to join (fix) a pipe made of synthetic resin such as polyethylene to a specified joint, such as a metal valve body.

The structure of such a fitting is such that, for example, the tip surface of the plastic pipe is inserted into a plastic pipe connection part formed integrally or separately from the metal pipe fitting body while expanding its diameter around the outer periphery of the fitting, and then a ring-shaped clamping member (ring) attached to the plastic pipe is pressed into the fitting while clamping the outer periphery of the plastic pipe.

Resin pipes can shrink at low temperatures and thin over time. This can create a gap between the outer periphery of the resin pipe and the ring that is pressed into place around the outer periphery of the metal groove. When external forces such as vibration or impact are applied to the ring or resin pipe, the ring can loosen or move from its original fixed position and come out. There is also the risk that the loosened ring will cause the shrunk resin pipe to come off the fitting.

Various joint structures have been proposed to address this issue. In particular, Patent Document 1 discloses a joint structure in which a recess is formed on the inner circumference of the clamping ring, and a first convex portion is formed in a position facing this recess on a plastic pipe connection part having a first convex portion and a second convex portion, with the first convex portion being higher than the second convex portion, and the plastic pipe is deflected radially in the portion sandwiched between the recess and the first convex portion.

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 plastic pipe connection section has multiple protrusions of different heights, with the protrusion with the largest outer diameter formed in a position facing the expanded diameter section on the inner circumference of the ring.

Japanese Patent Application Laid-Open No. 2015-166601 JP 2015-152064 A

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 protrusion, and a large amount of resin material from the resin tube is allowed to fill the recess, preventing the ring from coming off and preventing the resin material from spilling out of the ring at the back. However, to fill the recess sufficiently with resin material, the resin tube is bent radially by the tall first protrusion, and the resin material from the resin tube is allowed to fill the recess on the inner circumference of the ring opposite the protrusion.

For this reason, to prevent the ring from coming off, it is necessary to deform the plastic pipe toward its outer diameter. However, the amount of plastic material that fills the recesses of the bamboo grooves is reduced by the amount of plastic material that is deformed and forced into the recesses, which may reduce the fixing force that secures the plastic pipe to the joint.

The joint structure of Patent Document 2 has an expanded diameter section at the rear of the ring. When 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. One end of the plastic pipe, which is pressed against the expanded diameter section of the ring, expands in diameter toward the rear along the inner diameter of the expanded diameter section. A protrusion formed on the expanded diameter section bites into the outer surface of the plastic pipe. The protrusion that bites into the plastic pipe acts as a stopper, preventing the ring from coming off the plastic pipe.

However, the protrusions on the inner circumference of the ring are formed only on the enlarged diameter portion, and the outer surface of the resin pipe and the inner surface of the ring are brought into close contact with each other before the protrusions on the enlarged diameter portion are forced into the outer surface of the resin pipe.In order to make it easier to bring the outer surface of the enlarged resin pipe into close contact with the inner surface of the ring, the height of the protrusion facing the enlarged diameter portion is made larger than the other protrusions, and as it is larger than the other protrusions, it becomes easier for the resin material on the outer surface of the resin pipe to be 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 resin pipe and the outer surface of the resin pipe connection part, will decrease, resulting in a decrease in the fixing force that fixes the resin pipe to the joint part.

In addition, the resin material that makes up the resin pipe initially retains an elastic force (internal stress) that attempts to restore its shape in response to external deforming forces. However, when repeated external stresses or thermal changes are applied, this elastic force (internal stress) gradually decreases (creep), and eventually the internal stress reaches zero (creep limit).

If the resin pipe has not reached its creep limit, its elastic force will be able to hold the ring in place even if it shrinks to a certain extent. However, if the resin pipe has reached its creep limit, it will no longer be able to exert elastic force toward the ring, and its effectiveness in preventing the ring from moving will be significantly reduced.
If the ring cannot be reliably prevented from coming off, the fixing force for fixing the plastic pipe to the joint portion will be weakened, and the plastic pipe may come off from the joint portion.

The joint structures in the above-mentioned documents 1 and 2 do not take into consideration whether the ring can be prevented from coming loose or whether the fixing force that secures the plastic pipe to the joint can be maintained until the plastic pipe reaches its creep limit.

The present invention was developed to solve the above problems, and its purpose is to provide a valve with a plastic pipe fitting and a plastic pipe fitting that allows the ring to remain in its original fixed position while still maintaining sufficient fixing force to the plastic pipe connection.

In order to achieve the above object, the invention of claim 1 is a valve with a plastic pipe fitting, in which a fitting portion having a plastic pipe connection portion with unevenness on its outer periphery 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 press-fitted from the outer periphery of the plastic pipe to fix the plastic pipe to the fitting portion, wherein the valve body side of the fixing ring is provided with a tapered surface which expands in diameter towards the valve body side, and a filling space into which the plastic pipe is filled is provided by this tapered surface and an engaging surface of a flange portion provided on the outer periphery of the fitting portion,
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 resin pipe intersect, which is pushed out by press-fitting the ring into the resin pipe, to the sum of the volume of the filling space and the total volume of the recessed portion of the resin pipe connecting portion is 0.8 or more and 1 or less;
A wedge-shaped groove having a smaller volume than the filling space is formed on the inner circumference of the fixing ring, and when the fixing ring is pressed onto the outside of the plastic pipe, the plastic pipe is compressed and deformed on the outer circumference of the plastic pipe and escapes into the filling space. A portion of the amount of plastic pipe filled into the volume of the filling space enters the volume of the groove that is not included in the total volume of the filling space, forming a wedge portion. This wedge portion is locked into the groove, and the depth of the groove is such that it exerts a fixing force on the plastic pipe and prevents the fixing ring from falling off without affecting the filling of the resin material into the concave portions of the unevenness, and is of a minimum depth that prevents the fixing ring from moving from its fixed position even if the plastic pipe reaches its creep limit.

The invention according to claim 2 is a valve with a fitting for a plastic pipe , in which the groove is provided at a position facing the convex portion of the plastic pipe connecting portion, not facing the tapered surface .

The invention of claim 3 is a valve with a fitting for plastic pipes, in which the width of the groove is smaller than the width of the upper surface of the convex portion of the plastic pipe connection part that faces the groove.

The invention of claim 4 is a valve with a fitting for plastic pipes, in which the top of the groove is positioned within the width of the upper surface of the convex part of the plastic pipe connection part that faces the groove.

The invention of claim 5 is a valve with a fitting for plastic pipes, in which the multiple protrusions formed on the outer periphery of the plastic pipe connection portion have the same radial height.

The invention of claim 6 is a valve with a fitting for plastic pipes, in which the cross-sectional shape of the groove is wedge-shaped, inverted V-shaped, or triangular.

The invention according to claim 7 is a plastic pipe joint in which a joint body is formed with a plastic pipe connecting portion having an uneven outer periphery, a plastic pipe is inserted into this plastic pipe connecting portion, and a fixing ring is press-fitted from the outer periphery of the plastic pipe to fix the plastic pipe to the joint body, and a tapered surface is provided on the joint body side of the fixing ring, the diameter of which increases towards the joint body side, and a filling space into which the plastic pipe is filled is provided by this tapered surface and an engaging surface of a flange portion provided on the outer periphery of the joint body,
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 resin pipe intersect, which is pushed out by press-fitting the ring into the resin pipe, to the sum of the volume of the filling space and the total volume of the recessed portion of the resin pipe connecting portion is 0.8 or more and 1 or less;
A wedge-shaped groove having a smaller volume than the filling space is formed on the inner circumference of the fixing ring, and when the fixing ring is press-fitted onto the outside of the plastic pipe, the plastic pipe is compressed and deformed on the outer circumference of the plastic pipe and escapes into the filling space, and a part of the amount of plastic pipe filled into the volume of the filling space enters into the volume of the groove that is not included in the total volume of the filling space, forming a wedge portion, which is locked into the groove, and the depth of the groove does not affect the filling of the resin material into the concave portions of the unevenness, but exerts a fixing force for the plastic pipe and prevents the fixing ring from falling off, and is of a minimum depth that prevents the fixing ring from moving from its fixed position even if the plastic pipe reaches its creep limit.

The invention according to claim 8 is a joint for plastic pipes , wherein the groove is provided at a position facing the convex portion of the plastic pipe connecting portion, not facing the tapered surface .

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 plastic material on the outer circumference of the plastic pipe enters the groove, forming a wedge portion in the plastic pipe. This wedge portion engages with the groove in the fixing ring, and the fixing ring, which clamps and fixes the plastic pipe by means of a wedge action, can be reliably fixed in its fixed position.
The compressed and deformed resin tube escapes into the filling space, and a portion of the resin tube filled in the volume of the filling space enters into the groove volume that is not included in the total volume of the filling space, forming a wedge portion, thereby minimizing the depth of the groove. Therefore, the filling space can be provided without considering the resin material that will enter the groove. When the resin material enters the groove to form a wedge portion, both the fixing force of the resin tube and the effect of the groove to prevent the ring from falling off are fully exerted, and even when the resin tube has shrunk to its maximum and reached its creep limit, the engagement between the groove portion of the ring and the wedge portion is maintained, so that the wedge does not come off and the wedge action of the wedge portion prevents the fixing ring from moving from its predetermined fixed position, reliably preventing the fixing ring from moving or coming off.
Furthermore, the volume of the extruded resin material escapes into the filling space as the resin material of the resin pipe escapes, filling the specified volume, and the filling of this resin material allows the resin pipe to exhibit sealing properties and pull-out resistance at the connection part.

In addition, the groove on the inner circumference of the fixing ring is just deep enough to prevent the fixing ring from moving from its fixed position even when the plastic pipe reaches its creep limit. This means that there is no need to make it excessively deep to prevent the fixing ring from coming loose, and only a minimum amount of plastic material gets into the groove. This allows the plastic material to be fully filled into the recesses of the bamboo-shaped groove, maintaining good adhesion (fixing the plastic pipe) between the inner surface of the plastic pipe and the outer surface of the plastic pipe connection part.

It is particularly suitable for pipe fittings that connect to valves, and even when plastic pipes are prone to creep and reach their limit, it can maintain the fixing force of the plastic pipe fixed to the fitting while preventing the fixing ring from coming loose.

In this 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 cases where only plastic pipe shrinkage is taken into consideration, 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, even when the valve connected to the plastic pipe is used for long periods of time or under heavy loads that make plastic pipe creep more likely, such as when the valve is subjected to repeated thermal cycles or stress is applied to the plastic pipe connection.

According to the invention described in claim 2, the groove portion is provided in a position facing the convex portion of the resin pipe connection portion that does not face the tapered surface . Therefore, the tapered surface of the fixing ring is filled with the resin material that escaped when the fixing ring was pressed in, and the convex portion located in a position facing the groove portion ensures that the resin material enters the groove portion, forming a wedge portion and reliably fixing the fixing ring in place.

In addition, if a groove is provided on the flat surface of the inner circumference of the ring, which is not tapered, the tapered surface makes it easier to press the fixing ring into place, and the flat surface distributes the stress when pressing the ring into place, preventing the plastic tube from breaking and reducing distortion and deformation of the plastic tube, while also fixing the position of the fixing ring and preventing it from coming loose.

According to the invention of claim 3 or claim 4, the width of the groove of the fixing ring is formed smaller than the width of the upper surface of the convex part of the resin pipe connection part that faces this groove, or the top of the groove is positioned within the width of the upper surface of the convex part of the resin pipe connection part that faces this groove. Therefore, the convex part that faces the groove of the ring can reliably push the resin material into the groove, and even if the groove depth of the groove is minimal, a wedge part is formed on the outer surface of the resin pipe, and the groove can be engaged with the wedge part so that the wedge action can be fully exerted, so that the fixing ring can be held in a predetermined fixed position.
Furthermore, the amount of resin material that gets into the groove is minimal, and the recess necessary for fastening the resin pipe and the resin pipe connecting portion can be filled with sufficient resin material, thereby fixing and holding the resin pipe to the joint portion.
Therefore, even if the resin pipe shrinks due to long-term use, the ring can be prevented from coming off and the resin pipe can be fixed and held in place.

According to the invention described in claim 5, the multiple protrusions on the outer periphery of the resin pipe connection part of the joint part have the same radial height, so that the resin material pushed out radially by these protrusions can be reduced while more resin material from the resin pipe can be filled into the recesses of the bamboo-shaped grooves of the resin pipe connection part when the ring is pressed in, thereby increasing the adhesion between the resin pipe and the resin pipe connection part.
Therefore, even if creep occurs in the plastic pipe of the plastic pipe fitting connected to the valve and the plastic pipe shrinks to its maximum, the fixing force of the plastic pipe fixed to the fitting portion can be maintained, preventing the plastic pipe from coming loose from the fitting portion.

According to the invention described in claim 6, the cross-sectional shape of the groove is wedge-shaped, V-shaped, or triangular, which makes it easy for the resin material to enter the groove when the ring is press-fitted, making it easy to form a wedge portion. Furthermore, the wedge-shaped, V-shaped, or triangular wedge portion formed by filling the cross-sectional shape with the resin material easily catches in the groove on the inner circumference of the ring, easily exerting a wedge effect to prevent the ring from moving or slipping out of the resin tube.

According to the invention of claim 7, in a plastic pipe joint, a wedge-shaped groove is formed on the inner circumference of the fixing ring, and when the fixing ring is press-fitted onto the outside of the plastic pipe, a portion of the resin material on the outer circumference of the plastic pipe enters and forms a wedge portion in the plastic pipe. This wedge portion engages with the groove in the fixing ring, and the fixing ring, which tightens and fixes the plastic pipe by means of a wedge action, can be reliably fixed in place.
Furthermore, the compressed and deformed resin pipe escapes into the filling space, and a portion of the resin pipe filled into the volume of the filling space enters into the groove volume that is not included in the total volume of the filling space, forming a wedge portion, thereby minimizing the depth of the groove. Therefore, the filling space can be provided without considering the resin material that will enter the groove. When the resin material enters the groove to form a wedge portion, both the fixing force of the resin pipe and the effect of the groove to prevent the ring from falling off are fully exerted, and even when the resin pipe has shrunk to its maximum and reached its creep limit, the engagement between the groove portion of the ring and the wedge portion is maintained, so that the wedge does not come off and the wedge action of the wedge portion prevents the fixing ring from moving from its predetermined fixed position, reliably preventing the fixing ring from moving or coming off.
Furthermore, the volume of the extruded resin material escapes into the filling space as the resin material of the resin pipe escapes, filling the specified volume, and the filling of this resin material allows the resin pipe to exhibit sealing properties and pull-out resistance at the connection part.

In addition, the groove on the inner circumference of the fixing ring is only deep enough to prevent the fixing ring from moving from its fixed position even when the plastic pipe reaches its creep limit. This means that there is no need to make it excessively deep to prevent the fixing ring from coming loose, and only a minimum amount of plastic material gets into the groove. This allows the plastic material to be fully filled into the recesses of the bamboo-shaped groove, maintaining good adhesion between the inner surface of the plastic pipe and the outer surface of the plastic pipe connection.

According to the invention described in claim 8, the groove portion is provided at a position opposite the convex portion of the resin pipe connection portion that does not face the tapered surface . Therefore, the tapered surface of the fixing ring is filled with the resin material that escaped when the fixing ring was pressed in, and the convex portion located at a position opposite the groove portion ensures that the resin material enters the groove portion, forming a wedge portion and thereby reliably fixing the fixing ring in position.

In addition, if a groove is provided on the flat surface of the inner circumference of the ring, which is not tapered, the tapered surface makes it easier to press the fixing ring into place, and the flat surface distributes the stress when pressing the ring into place, preventing the plastic tube from breaking and reducing distortion and deformation of the plastic tube, while also fixing the position of the fixing ring and preventing it from coming loose.

1 is a partially cutaway vertical cross-sectional view of a valve with a joint for a plastic pipe according to the present embodiment. 2 is a cross-sectional view of the plastic pipe joint with the valve body of the plastic pipe joint-equipped valve of FIG. 1, with the joint portion separated from the valve body. 4 is a diagram illustrating a state in which a fixing ring is fixed to a joint portion in the joint for plastic pipes of this example. 1 is a diagram schematically illustrating a state in which the plastic pipe is maximally contracted in the plastic pipe joint of this example. 1A and 1B are explanatory diagrams showing the procedure for inserting a plastic pipe into a plastic pipe fitting of this example and pressing in a ring, 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 in the ring. FIG. 10 is a cross-sectional view of another example of a valve with a joint for a plastic pipe.

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

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, it can be used not only for valves, but also for various joint structures for connecting plastic pipes to objects, such as male/female thread sockets and couplers, as appropriate for the implementation.

As shown in Figure 1, the valve body 2 in this example is a valve 1 with a plastic pipe fitting, which includes a body portion 3 and a fitting portion 4, with a plastic pipe 5 fixed to the fitting portion 4 via a fixing ring 6 (hereinafter sometimes referred to as the "ring"). A disc 7 (valve element) is housed within the body portion 3 so that it can move up and down in a direction intersecting the axial direction of the flow path, and a bonnet 8 with a mounting portion is connected to the top of the body portion 3.

In Figure 1, a stem 9 is housed within the bonnet 8, concentric with its axis. A female thread 8a is provided on part of the inner surface of the bonnet 8, and the male thread 9a of the stem 9 is threadedly engaged with this 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 to the upper end of the stem 9 concentrically and rotatably with the stem 9 by tightening a hexagonal nut 10. A packing nut 14 that tightens a packing 13 via a gland 12 is threadedly attached to the upper end of the mounting portion of the bonnet 8, and the inside and outside of the mounting portion are sealed by tightening this packing nut 14.

In Figure 1, in this example of a valve with plastic pipe fitting 1, by manually rotating the round handle 11, the stem 9 moves up and down within the valve stroke range in response to the threading between the male thread 9a and the female thread 8a, while the seal of the shaft mounting portion is maintained by the packing 13. In response to this movement, the disc 7, which is 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.

The body 3 has a female thread 3a that can be connected to a fitting 4 for connecting plastic pipes. The body 3 also has a hexagonal nut 15 that can be used to lock a jig when attaching the fitting 4, inserting the plastic pipe 5, or press-fitting the ring 6.

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 of the flange portion 42. This male thread portion 43 is threaded into the female thread portion 3a of the body 3, connecting the body 3 and the joint portion 4 together as a single unit.
The flange 42 of the joint 4 has a two-sided width 44 formed on its outer periphery, which can be engaged with a jig used to attach the joint 4 to the valve body 2. This two-sided width 44 can also be engaged with a jig used to press-fit the fixing ring 6 after inserting the plastic pipe 5. Instead of a two-sided width, the outer periphery of the flange 42 may be shaped like a hexagonal nut.

In addition, while the fitting and body are formed separately in this example, a valve body in which the fitting 4 is integrally formed with the body 3, as shown in Figure 6, may also be used. As long as it at least functions as a fitting structure, the structure of the plastic pipe fitting of the present invention can be selected as desired depending on the implementation. Note that a structure equipped with the fitting of the present invention is referred to as a plastic pipe fitting.

The plastic pipe fitting 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 fitting, with the fitting portion 4 separated from the valve body 2 of the plastic pipe fitting-equipped valve 1 of this example in Figure 1. Figure 3 is a diagram illustrating the state in which the fixing ring 6 is fixed to the fitting portion 4 of the plastic pipe fitting of this example. Figure 4 is a diagram schematically illustrating the state in which the plastic pipe fitting of this example has been maximally contracted. Hereinafter, the side of the plastic pipe fitting that connects to the body 3 of the valve body 2 (the valve body side or fitting 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.

As shown in Figures 2 and 3, the fitting 4 has a plastic pipe connection portion (connection portion) 41 that extends toward the tip (axial direction). The outer periphery of the connection portion 41 is uneven, and the tip side of the connection portion 41 is formed with an inclined surface 46 that tapers toward the front. The inclination angle of the inclined surface 46 with respect to the axial direction of the fitting (axial direction in Figure 2) is preferably in the range of 15 to 30 degrees, as this facilitates insertion of the plastic pipe 5.

The unevenness of the connection portion 41 consists of multiple convex portions (21, 22, 23, 24) and concave portions (26, 27, 28, 29) arranged in an uneven pattern, with each concave and convex portion being annularly arranged on the outer circumferential surface in a direction intersecting the axial direction of the connection portion. In this example, the cross-sectional shapes of each concave (convex) portion are arranged to be approximately the same, but the length and diameter of the connection portion, as well as the number and cross-sectional shape of the concave and convex portions, are not limited to the structure of this example and can be selected as desired depending on the implementation. Hereinafter, convex portion 21 may be referred to as the first convex portion, and convex portion 22 as the second convex portion, etc.

As shown in FIGS. 3 and 4, each of the convex portions (21, 22, 23, 24) has a substantially trapezoidal cross section and a flat upper surface.
Each protrusion has an inclined surface that slopes toward the recess on the near side, and these inclined surfaces (21a, 22a, 23a, 24a) function as guides when inserting the resin tube 5. When the ring 6 is pressed into place, they 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 this function. Note that each inclined surface does not necessarily need to reach each recess, but in order to effectively provide this function, it is preferable that each inclined surface reach the bottom of each recess.

3, a convex portion (first convex portion) 21 is provided at the innermost side (innermost portion) of the boundary portion 30 between the engagement surface 45 of the flange portion 42 and the connecting portion 41. The width and height of the upper surface of this convex portion 21 are the same as the width and height of the upper surfaces of the other convex portions.
In this way, the convex portion 21 is provided at the innermost portion in a position opposite the tapered surface 62 of the fixing ring 6 described later, so that 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, which is difficult to fill with the resin material of the resin tube 5, making it easier to fill the resin material into each concave portion (26, 27, 28, 29).

The resin pipe 5 connected to the joint 4 is made of synthetic resin and has compressive deformation properties. For example, it can be applied to a relatively large diameter hard material such as polyethylene water pipe, but it can also be a resin pipe made of other synthetic resins.
When inserting the resin pipe 5 into the connecting portion 41 , the resin pipe 5 is inserted to the deepest part so that the tip end surface 51 of the resin pipe 5 abuts against the engagement surface 45 of the flange portion 42 of the joint portion 4 .

When inserting the plastic pipe 5 into the connection part 41, a fixing ring 6 is attached to the plastic pipe 5 in advance. After inserting the plastic pipe 5 into the connection part 41, the fixing ring 6 tightly fastens the plastic pipe 5 to the connection part 41, completely securing the plastic pipe 5 to the fitting part 4.

Furthermore, when the ring 6 is press-fitted into the plastic pipe 5, part of the outside of the plastic pipe 5 enters the groove 61 of the ring 6, and a wedge portion 52 is formed integrally with the outer periphery of the plastic pipe 5. This wedge portion 52 engages with the groove 61 of the ring 6, exerting the wedge action described below, which can secure the ring 6 in a predetermined fixed position.

The fixing ring 6 is an annular fastening member that is integrally formed from metal and has a predetermined thickness. As shown in Figure 2, a wedge-shaped groove 61 is provided on the inner peripheral surface of the fixing ring 6, and one end surface forms an insertion end 63 that abuts against the engagement surface 45 of the flange 42. The inner peripheral surface of the insertion end 63 forms a tapered surface 62 that expands in diameter toward the back.
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).

Furthermore, if the tapered surface 62 of the ring 6 has a certain degree of surface roughness, it can 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 are rounded, this is preferable because it makes it less likely for damage to occur to the plastic pipe 5 and makes it easier to prevent breakage of the plastic pipe 5 when it is fixed.

The inner diameter of the fixing ring 6 is set smaller than the outer diameter of the resin pipe 5, and the ring 6 is previously arranged in a loose fit state in the resin pipe 5 before being fixed, 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 connecting portion 41 and the filling space (described later) satisfies a predetermined relationship with the compressed volume of the resin material of the compressed resin pipe 5.

The groove 61 on the flat surface 65 of the ring 6 has a wedge-shaped, V-shaped, or triangular cross-sectional shape. The groove 61 is preferably located in the vicinity of the tapered surface 62 of the ring 6, facing a convex portion that does not face the tapered surface 62 that expands in diameter toward the valve body (joint body).

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

When the ring 6 is press-fit onto the outside of the plastic pipe 5, part of the outside of the plastic pipe 5 enters the groove 61, forming a wedge portion 52 on the outer surface of the plastic pipe 5. This wedge portion 52 engages within the groove 61, allowing the ring 6 to be fixed in a predetermined position.

Furthermore, since the cross-sectional shape of the groove 61 is wedge-shaped, V-shaped, or triangular, the resin material easily enters the groove 61 when the ring is press-fitted, easily forming a wedge portion. The wedge portion formed by filling the resin material easily becomes caught in the groove portion on the inner periphery 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 wedge-shaped, V-shaped, or triangular, but other shapes are also acceptable as long as the wedge portion 52 can be formed. Examples of other shapes include a U-shaped, C-shaped, arc-shaped, or U-shaped cross-sectional shape. Multiple grooves may also be provided on the inner circumference of the ring. However, from the viewpoint of filling as much resin material as possible into the recess of the resin pipe connecting portion, it is preferable to have as few grooves as possible.

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 surface 51 side of the resin pipe fills the tapered surface 62 and the bamboo-strip groove (recess) before filling the groove, which may result in an insufficient filling of the resin material in the groove, and may not be able to sufficiently prevent 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 also preventing the resin tube from breaking.

As shown in Figure 4, the axial width a of the groove 61 is within the axial width b of the opposing protrusion 22, but is smaller than the axial width b of the protrusion 22. To make it easier for the opposing protrusion to push the resin material into the groove 61, it is more preferable for a to be less than half the width b.

The depth c of the groove 61 is set to the minimum depth that prevents the ring 6 from moving from its fixed position even when the resin pipe 5 reaches the limit of its creep state.
Here, "the ring 6 does not move from its fixed position even when the plastic pipe 5 reaches its creep limit" means that even when repeated stress, etc. is applied to the plastic pipe 5, it reaches its creep limit, and maximum shrinkage occurs in the plastic pipe 5, but the ring 6 does not move from its original 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 can 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 d of the radial top of the wedge portion 52 after shrinkage when the resin pipe 5 has shrunk to the maximum.

In this way, even if the resin pipe 5 shrinks, the depth of the groove 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 resin pipe.

Furthermore, the positional relationship between the groove 61 of the ring 6 and the convex portion 22 facing this 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 ensures that the resin material of the resin tube 5 can be filled up to the top of the groove 61. The width a of the groove 61 is preferably set within the width of the convex portion 22 and the inclined surface 22a on its front side. 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 forward, the resin material pressed by the top surface of the convex portion 22 when the ring 6 is pressed into the groove 61 will be more easily filled.

After connecting the resin pipe, if it is used for a long period of time and subjected to temperature changes and various stresses, the resin pipe will creep, but by providing a groove in 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 that can occur 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 plastic pipe, and by providing a groove that is 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 portion 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 groove depth, it can be preferably within 3 times, more preferably within 2 times.

Here, a valve is a pressure vessel placed between flow paths that allows, stops, and controls the flow of fluid within the flow paths, and the parts that come into contact with the fluid are affected by the fluid's pressure and temperature. For this reason, pressure and temperature fluctuations are likely to occur before and after the valve switches between opening and closing, and the joints that connect to the valve tend to be susceptible to pressure fluctuations and temperature changes as well, making creep likely to occur in the plastic pipes connected to the joints.

For this reason, if the plastic pipe in a plastic pipe fitting shrinks due to pressure fluctuations or temperature changes, the plastic pipe will creep over long-term use and lose its elasticity when it reaches its limit.

If the resin pipe has not reached its creep limit, its elastic force will be able to hold the ring in place even if it shrinks to a certain extent. However, if the resin pipe has reached its creep limit, it will no longer be able to exert elastic force toward the ring, and its effectiveness in preventing the ring from moving will be significantly reduced.
If the ring cannot be reliably prevented from coming off, the fixing force for fixing the plastic pipe to the joint portion will be weakened, and the plastic pipe may come off from the joint portion.

With conventional joint structures, there is a risk that the retaining ring may not be reliably prevented from coming off the plastic pipe when the plastic pipe has shrunk to its maximum and reached its creep limit. If the ring cannot be prevented from coming off when the plastic pipe has reached its creep limit, the retaining ring may become loose or rattle, reducing not only the retaining force (clamping force) of the retaining ring but also the force securing the plastic pipe to the joint, potentially causing the plastic pipe to come off the joint.

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.
Therefore, it is suitable even when the resin pipe shrinks and reaches its creep limit, making it susceptible to maximum shrinkage, and is particularly suitable for resin pipe joints that are connected to valves.
Furthermore, since the depth of the 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 the resin pipe connection portion 41 described below, while increasing the adhesion between the inner surface of the resin pipe 5 and the outer surface of the resin pipe connection portion 41.

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 part 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.

In Figure 3, the innermost side surfaces of the recesses 26, 27, 28, and 29 are tapered inclined surfaces 21a, 22a, 23a, and 24a whose outer periphery slopes toward the innermost side, and the inclination angle of these surfaces is an angle _θ1 (e.g., approximately 60 degrees) with respect to the axial direction (horizontal direction in Figure 3) of the joint portion 2. On the other hand, the outer side surfaces facing these inclined surfaces 21a, 22a, 23a, and 24a are vertical surfaces oriented in a direction intersecting the axial direction of the joint portion 4. As shown by dashed lines in the figure, the volumes of the annular spatial regions within the recesses 26, 27, 28, and 29 are denoted by _A1 , _A2 , _A3 , and _A4 , respectively. The width of the cylindrical bottom surface of each recess (the horizontal length in FIG. 3) is indicated by m, the diameter of each bottom surface 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, this n is referred to as the width of the recess. Furthermore, if the diameter of the cylindrical top surface of each protrusion 21, 22, 23, 24, 25 is indicated by _φD1 and the height of each protrusion is indicated by 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 connecting portion 41.

The angle _θ2 is preferably in the range of 15 to 30 degrees. If this angle is too small, the resin pipe 5 is easier to insert but may be more likely to come out, while if the angle is too large, stress is applied to the resin pipe 5 during insertion, making it more 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 resin pipe connecting portion 41, as this makes it easier to insert the resin pipe 5.

In addition, in the same figure, the inner diameter of the ring 6 is shown as _φd2 , the diameter of the outer boundary 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 between the opposite tapered surface 64 and the cylindrical inner surface and the position of the insertion end 63 is shown as _L2 .

In Figure 3, when the insertion end 63 of the ring 6 abuts against the engagement surface 45 and the fixation of the plastic pipe 5 is completed, an annular space with a substantially triangular cross section, designated by _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, which is 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, which has been compressed and deformed by the press-fitting of the ring 6, escapes.
Furthermore, 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 amount of 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 groove preventing the ring from falling out 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.

In Figure 3, the annular spatial area indicated by cross-hatching virtually represents the area where the inner circumference of the ring 6 and the resin tube 5 intersect.

That is, when the resin pipe 5 is fitted onto the outer periphery of the joint 4 while expanding in diameter without changing its thickness, and the inner periphery of the ring 6 at the press-fit completion position is imagined to overlap the outer periphery of the resin pipe 5 in this state, an intersecting 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 intersecting region. Also, the thickness of the resin pipe 5 is generally equal to _φD2 - _φD1 in the figure.

Incidentally, the area into which the resin material can escape due to such extrusion, disregarding deformation or escape of the resin material outward from the area compressed by the ring 6, is, in this example, the volume within all of the recesses 26-29 and the volume of the filling space. Therefore, if the total volume of all of these recesses 26-29 and the volume of the filling space is the same or smaller than the volume of the intersection area, it can accommodate at most the escape volume of the resin material due to compression deformation. Therefore, as the ring 6 is pressed into place, the compressed and deformed resin material will not extrude from the back side of the ring 6, i.e., from between the insertion end 63 and the engagement surface 45, unless the resin expands.

In contrast, _A1 to _A4 are the volumes inside the recesses 26 to 29, respectively, and _A5 is the volume of the filling space. Furthermore, _A6 is the volume of the resin material to be extruded, and is approximately equal to the volume of the intersection region, so if _A6 is the same as or smaller ( _1.0 or less) than the sum of A1 to _A5 , it will be possible to accommodate at least the maximum volumetric amount of compressive deformation of the resin material of the resin tube 5, thereby ensuring that the resin material is reliably filled into each of the recesses 26 to 29 while reliably preventing the resin material from spilling out.

On the other hand, if the volume that can tolerate deformation of the resin pipe 5 is too large, it may result in voids that are not filled with resin, resulting in insufficient filling. Therefore, it is preferable to set an appropriate lower limit for this ratio. However, if this lower limit is too close to 1.0, the volume that can tolerate resin deformation may be insufficient. For example, if a hard resin is subjected to uneven compressive deformation, it may partially deform beyond the allowable volume, resulting in resin overflow. Furthermore, it is preferable to set a lower limit that is somewhat common to different resin materials depending on the type of resin pipe 5. An example of such a lower limit is 0.8. To summarize the above, the following relationship is obtained.

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.

Although not shown, the present invention is not limited to the structure of this example, and can also be applied to general joints, plastic pipes, and rings. When a ring is imagined at the fully inserted position for a plastic pipe in a joint, an intersection region is created between the inner circumference of the ring and the outer circumference of the plastic pipe. The volume _V1 of this intersection region is approximately equal to the volume of the resin material extruded into the ring. Furthermore, 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 , then as long as at least _V2 + _V3 > _V1 , the resin material can be reliably filled into each recess while the volumetric structure ensures that the resin material does not spill out.

3, in this example, the protrusion 21 disposed at the boundary portion 30 is set to approximately the same height h as the protrusion 22 immediately outside it, but the height of the protrusion 22 may also be set slightly lower than h. In this case, even if the distal end surface 51 of the resin pipe 5 has not yet expanded in diameter when fully inserted into the fitting 4, the distal end surface 51 can reliably reach the engagement surface 45 without getting caught on the protrusion 21. Furthermore, in this fully inserted state, a small gap can be secured between the inner periphery near the distal end surface 51 and the upper surface of the protrusion 21, providing a space for the resin to escape as it is compressed and deformed, further reliably preventing the resin material from spilling out.
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 has been installed.

Next, we will explain the valve with a plastic pipe fitting and the method for fixing a plastic pipe to the connection portion of the plastic pipe fitting according to the present invention, as well as the operation of the plastic pipe fitting of the present invention. Figure 5 is an explanatory diagram that schematically shows the steps for inserting a plastic pipe into the plastic pipe fitting of this example and pressing in a ring. (a) shows the state in the middle of inserting the plastic pipe, (b) shows the state after the plastic pipe has been inserted, and (c) shows the state in the middle of pressing in the ring.

5(a), the inner periphery of the resin pipe 5 is brought close to the connecting portion 41 so as to fit into it, and the resin pipe 5 is inserted into the connecting portion 41 while expanding its diameter. When the resin pipe 5 is inserted toward the back side of the axial center of the connecting portion 41, the inclined surface 46 slides onto the inner periphery of the resin pipe 5 while expanding the diameter of the resin pipe 5.
The inner diameter of the resin pipe 5 is smaller than the outer diameter of the connecting part 41 by a predetermined ratio, and the inclined surface 46 protrudes toward the front side, so that the inside of the tip surface 51 of the resin pipe 5 can be easily covered over the entire circumference while being centered on the inclined surface 46, making it easy to insert the resin pipe 5.

Figure 5(b) shows the state in which the tip surface 51 is in even contact with the engagement surface 45 of the flange 42 over the entire circumference, completing the insertion of the plastic pipe 5. In this state, the area near the inner periphery of the tip surface 51 of the plastic pipe 5 evenly covers the entire circumference of the top surface of the innermost convex portion 21 (first convex portion).

Figure 5(c) shows the state in the middle of press-fitting the ring. The ring 6 is press-fitted onto the plastic pipe 5, which has been completely inserted into the connection part 41, completely fixing the plastic pipe 5 to the joint part 4 and completing the connection of the plastic pipe 5.

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 has an expanded diameter, and then the fixing ring 6 is press-fitted.
Here, the tapered surface 62 is adapted to 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.

When the ring 6 is pressed into the resin pipe 5, the flat inner surface 65 of the ring 6 compresses the outer surface of the resin pipe 5, the inner surface of the resin pipe 5 and the outer surface of the connecting portion 41 come into close contact, and the resin material on the inner surface of the resin pipe 5 is pushed into the recesses of the connecting portion 41, and the resin material fills all of the recesses of the connecting portion.
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 , forming a wedge portion 52 integrally with the outer periphery of the resin pipe 5 .

In other words, during the process of pressing the ring 6 into the plastic pipe 5, a volume equivalent to the plastic material of the plastic pipe that abuts against the flat surface 65 is pushed out by compression and deformation, filling the recess in the connection portion 41, and some of the plastic material escapes into the filling space at the back, filling the filling space. Meanwhile, a wedge portion 52 is integrally formed on the outer circumferential surface of the plastic pipe.

If there is no compression or expansion of the resin material, the volume of the extruded resin material will escape into the recess or filling space due to this extrusion, filling the specified volume. As a result of this filling of the resin material, the resin pipe 5 will be fixed to the connection part 41, providing sealing properties and pull-out resistance.

The innermost convex portion 21 (first convex portion) is located at the boundary 30 between the engagement surface 45 and the connection portion 41. This makes it 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 improved, giving the resin pipe 5 high pull-out resistance and sealing properties.

Furthermore, a groove 61 is provided on the inner periphery of the fixing ring 6, and when the fixing ring 6 is completely press-fitted into the resin pipe 5, a wedge portion 52 formed on the outer periphery of the resin pipe 5 engages with the groove on the inner periphery of the ring 6, so that the wedge portion 52 exerts a wedge action against the movement of the ring 6 fixed to the resin pipe 5. In other words, when a moving force acts on the ring 6 fixed to the resin pipe 5, the wedge portion 52 acts as 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 original fixed position.

The depth of the groove 61 is set to the minimum depth that prevents the fixing ring 6 from moving from its fixed position even when the resin pipe 5 reaches its creep limit. Therefore, even when the resin pipe 5 reaches its creep limit and shrinks to its maximum, the fixing ring 6 will not come off the resin pipe 5, and the fixing ring 6 can be kept in its original fixed position.
That is, as shown in FIG. 4, the radial depth c of the groove 61 is greater than the radial shrinkage d of the top of the wedge portion 52 when the resin pipe 5 shrinks. Therefore, even when the resin pipe 5 shrinks to its maximum, the groove 61 of the ring 6 and the wedge portion 52 remain engaged with each other, and the wedge action of the wedge portion 52 reliably prevents the fixing ring from moving or coming off, and the fixing ring 6 can be held in its original fixed position.

In addition, the groove 61 on the inner circumference of the ring 6 is of a minimum depth that prevents 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 it excessively deep to prevent the ring 6 from coming off, and only a minimum amount of plastic material needs to enter the groove 61. This allows the plastic material to be sufficiently filled into the recess of the bamboo-shaped groove, maintaining good adhesion between the inner surface of the plastic pipe 5 and the outer surface of the plastic pipe connection part 41. This makes it easier to maintain the fixing force that secures the plastic pipe 5 to the fitting part 4 even when the plastic pipe 5 shrinks to its maximum.

The present invention therefore reliably prevents the ring 6 from coming off the plastic pipe 5 even when the plastic pipe 5 reaches its creep limit, while maintaining the fixing force that secures the plastic pipe 5 to the joint 4, thereby improving pull-out resistance and maintaining good sealing performance.

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 faces the protrusion 22 (second protrusion) on the near side adjacent to the protrusion 21 (first protrusion) at the innermost part of the resin pipe connecting portion 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 surface of the resin pipe 5.
Furthermore, only a minimum amount of resin material is required to form the wedge portion 52, and sufficient 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.

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 less likely to be damaged when the ring 6 is press-fitted.
Here, when the ring 6 is pressed in, the resin material on the outer surface of the resin pipe 5 is filled to fill the tapered surface 62, and the outer side of the resin pipe 5 is bent along the tapered surface 62, but the strength of the area around this bent portion tends to be inferior to other parts.
If the groove 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 resin pipe 5, which may become the starting point for the resin pipe 5 to break. However, since the groove 61 is provided so as to face 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 resin pipe 5 bends, making the resin pipe 5 less likely to break.

In addition, a tapered surface 62 is provided on the tip surface 63 of the fixing ring 6, so as the resin tube 5 is compressed and deformed, the resin material near the innermost region is pushed out and filled into the void filling space. The resin material of the compressed resin tube is reliably filled into the specified filling area, preventing the resin material of the resin tube from spilling out of the fixing ring 6.

Furthermore, since the groove 61 is provided on the inner side of the ring, the resin material of the resin tube can be sufficiently filled in the groove 61. If the groove 61 of the ring were provided closer to the front side (tip side), the resin material on the inner side would fill the tapered surface and the recesses of the bamboo shoot groove before being filled into the groove 61, which could result in an insufficient filling of the resin material in the groove 61 and the possibility that the ring 6 would not be able to be sufficiently prevented 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) that does not overlap 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, if the press-fitting direction of the ring 6 is fixed, there is a possibility that the operator may insert the ring 6 in the wrong direction. If it is important to prevent such an incorrect insertion direction, it is preferable to make the groove 61 on the inner periphery of the ring 6 face the central protrusion of the resin pipe connecting portion 41.

Furthermore, when the heights of the multiple protrusions provided on the outer periphery of the resin pipe connection part 41 are made the same, the amount of resin material of the resin pipe 5 pushed outward is minimized while a sufficient amount of resin material is secured to fill the recesses of the resin pipe connection part 41, and when the ring 6 is pressed in, a large amount of resin material of the resin pipe 5 can be filled into the recesses of the bamboo-shaped grooves of the resin pipe connection part 41, thereby increasing the adhesion between the resin pipe 5 and the resin pipe connection part 41.
Therefore, even if creep occurs in the plastic pipe of the plastic pipe fitting connected to the valve and the plastic pipe shrinks to its maximum, the fixing force of the plastic pipe fixed to the fitting portion can be maintained, preventing the plastic pipe from coming loose from the fitting portion.
In addition, when the fixing ring 6 is pressed into place, 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 place.

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 peripheral surface of the resin pipe.
Furthermore, the wedge portion 52 formed by filling the resin material easily catches in the groove portion 61 on the inner periphery of the ring 6, so that the wedge portion 52 easily fits into the groove portion 61 and exerts a wedge action on the ring 6. This allows the press-fitted fixing ring 6 to be held in a predetermined fixed position.

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

Furthermore, the present invention can be applied regardless of the diameter of valves, fittings, or plastic pipes, and does not require complex processing or design, which also contributes to cost reduction.

Next, Figure 6 is a cross-sectional view of another example of a valve with a fitting for plastic pipes 100. In Figure 6, except that the fitting portion 4 is integrally formed with the valve body 2, it is the same as the valve with a fitting for plastic pipes 1 described above, and the structure of the fitting portion is also the same, so identical parts are given the same reference numerals and their description will be omitted.

As shown in Figure 6, in this example, the fitting 4 is integral with the valve body 2, and the fitting 4 has a flow path formed within the plastic pipe connection portion 41 that protrudes linearly from both sides of the body 3. Because the fitting 4 is formed integrally with the body 3, plastic pipes can be connected directly to the valve body 2 without the need to prepare and attach a plastic pipe fitting.

The above describes the valve with fitting for plastic pipe of the present invention, but the same effects can be achieved when this fitting structure is applied to a fitting for plastic pipe. When applying the structure of the present invention to a valve or fitting, there are no size restrictions, but sizes of 20A to 100A, for example, are particularly suitable.

Furthermore, the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the invention as set forth in the claims of the present invention.

<Test Example>
The resin 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 resin pipe shrinks before and after a creep test.
The creep test involved polyethylene water supply pipes of various diameters, each connected to the aforementioned resin pipe joint structure. The polyethylene pipes were subjected to 1,000 hours of water temperature 80°C and internal pressure of 1.0 MPa. These conditions correspond to 50 years of use at 20°C (ISO 12162, 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 structures connected to both ends was measured. The difference between the outer diameters was used as the total pipe shrinkage, and half of this value was used as the shrinkage of the polyethylene pipe thickness.

Table 1 shows the test results. These results show that for polyethylene water supply pipes, the amount of shrinkage in pipe thickness is between 0.05 and 0.10 mm. Therefore, for example, if the depth of the groove 61 on the inner circumference of the fixing ring 6 is approximately 0.5 mm, it is possible to prevent the ring from coming loose even when the creep limit is reached and the plastic pipe shrinks to its maximum.

1 Resin pipe valve for resin pipe 2 Valve body 4 Joint part 5 Resin pipe 6 Fixing ring (ring)
21 convex portion (first convex portion)
22 convex portion (second convex portion)
41 Resin pipe connection part (connection part)
45 Engagement surface 51 Tip surface 52 Wedge portion 61 Groove portion 62 Tapered surface 63 Insertion end 65 Flat surface a Width of groove portion b Width of second convex portion c Depth of groove portion d Amount of shrinkage of the top of the wedge portion when the resin pipe shrinks

Claims (8)

A valve with a plastic pipe fitting has a fitting portion provided integrally with or separately from a valve body, the fitting portion having a plastic pipe connection portion with unevenness on its outer periphery, a plastic pipe is inserted into the plastic pipe connection portion, and a fixing ring is press-fitted from the outer periphery of the plastic pipe to fix the plastic pipe to the fitting portion, wherein the fixing ring has a tapered surface on the valve body side that expands in diameter toward the valve body side, and a filling space into which the plastic pipe is filled is formed by an engagement surface of a flange portion provided on the outer periphery of the fitting portion,
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 resin pipe intersect, which is pushed out by press-fitting the ring into the resin pipe, to the sum of the volume of the filling space and the total volume of the recessed portion of the resin pipe connecting portion is 0.8 or more and 1 or less;
a wedge-shaped groove formed on the inner periphery of the fixing ring, the groove having a volume smaller than that of the filling space; when the fixing ring is press-fitted onto the outside of the plastic pipe, the plastic pipe is compressed and deformed on the outer periphery of the plastic pipe and escapes into the filling space; a portion of the amount of plastic pipe filled into the volume of the filling space enters into the volume of the groove that is not included in the total volume of the filling space, forming a wedge portion; this wedge portion is locked into the groove; and the depth of the groove is such that it exerts a holding force for the plastic pipe and prevents the fixing ring from falling off without affecting the filling of the resin material into the concave portions of the unevenness; and the minimum depth is such that the fixing ring does not move from its fixed position even if the plastic pipe reaches its creep limit. A valve with a plastic pipe fitting as described in claim 1, wherein the groove is provided at a position facing a convex portion of the plastic pipe connecting portion that does not face the tapered surface. A valve with a plastic pipe fitting as described in claim 1 or 2, wherein the width of the groove is smaller than the width of the upper surface of the convex portion of the plastic pipe connecting portion that faces the groove. A valve with a plastic pipe fitting according to any one of claims 1 to 3, wherein the top of the groove is positioned within the width of the upper surface of the convex portion of the plastic pipe connecting part that faces the groove. A valve with a plastic pipe fitting according to any one of claims 1 to 4, wherein the multiple protrusions formed on the outer periphery of the plastic pipe connection portion have the same radial height. A valve with a fitting for a plastic pipe according to any one of claims 1 to 5, wherein the cross-sectional shape of the groove is wedge-shaped, inverted V-shaped, or triangular. A plastic pipe joint has a joint body formed with a plastic pipe connecting portion having an uneven outer periphery, a plastic pipe is inserted into this plastic pipe connecting portion, and a fixing ring is press-fitted from the outer periphery of the plastic pipe to fix the plastic pipe to the joint body, wherein the fixing ring has a tapered surface on the joint body side that expands in diameter toward the joint body, and a filling space into which the plastic pipe is filled is formed by an engagement surface of a flange portion provided on the outer periphery of the joint body,
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 resin pipe intersect, which is pushed out by press-fitting the ring into the resin pipe, to the sum of the volume of the filling space and the total volume of the recessed portion of the resin pipe connecting portion is 0.8 or more and 1 or less;
a wedge-shaped groove having a volume smaller than the filling space is formed on the inner periphery of the fixing ring, and when the fixing ring is press-fitted onto the outside of the plastic pipe, the plastic pipe is compressed and deformed on the outer periphery of the plastic pipe and escapes into the filling space, and a part of the amount of plastic pipe filled into the volume of the filling space enters into the volume of the groove that is not included in the total volume of the filling space, forming a wedge portion, which is locked into the groove, and the depth of the groove is such that it exerts a fixing force for the plastic pipe and prevents the fixing ring from falling off without affecting the filling of the resin material into the concave portions of the unevenness, and the depth is set to the minimum value that prevents the fixing ring from moving from its fixed position even if the plastic pipe reaches its creep limit. A plastic pipe fitting as described in claim 7, wherein the groove is provided at a position facing a convex portion of the plastic pipe connecting portion that does not face the tapered surface.