Sealing material used in pipe joint with spigot inserted into socket, and pipe joint using the same

Abstract

To provide a sealing material which is compressed to seal between a seal surface of a socket and an outer peripheral surface of a spigot, and which satisfies both requirements from a stress aspect during compression and requirements from a watertightness aspect.SOLUTION: A sealing material comprises: a heel part 13 that is fitted into a fitting groove 21 of a socket 2, and a valve part 10 that is compressed by being sandwiched between a sealing surface 23 of a socket 2 and an outer peripheral surface of a spigot 3. The valve portion 10 has a first convex part 11 formed on an outer peripheral side, and a second convex part 12 formed on an inner peripheral side. A first radius R1 of a first circle 11c including the arc-shaped outline of the first convex part 11 is smaller than a second radius R2 of a second circle 12c including the arc-shaped outline of the second convex part 12. The center C1 of the first circle is located inside the sealing surface 23 of the socket 2 in a pipe diameter direction, and is included in the circumference of the second circle 12c. The center-to-center distance between the center C1 of the first circle and the center C2 of the second circle in the pipe axial direction is smaller than the difference between the second radius R2 and the first radius R1.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sealing material used for a pipe joint in which an insertion port is inserted into a receiving port, and a pipe joint using this sealing material.

Background Art

[0002] Conventionally, as this type of sealing material, there is one used in a pipe joint 900 as shown in FIG. 9. In this pipe joint 900, an insertion port 3 formed at the end of one pipe to be connected to each other is inserted into a receiving port 2 formed at the end of the other pipe.

[0003] An annular sealing material 9 made of rubber is disposed in a sealing material placement recess 20 formed on the inner periphery of the receiving port 2, and a lock ring groove 24 is formed on the back side of the sealing material placement recess 20. A lock ring 25 is disposed in this lock ring groove 24. On the outer periphery of the tip 31 of the insertion port 3, a protrusion 31b that can be engaged with the lock ring 25 from the back side of the receiving port 2 is formed. An elastic member 26 for centering the lock ring 25 is disposed between the lock ring 25 and the lock ring groove 24.

[0004] As shown in FIGS. 9 and 10, the sealing material 9 has a heel portion 93 fitted into a first fitting groove 21 provided on the front side of the peripheral surface of the sealing material placement recess 20, and a sealing surface 23 on the peripheral surface and the outer peripheral surface of the insertion port 3. And a valve portion 90 fitted into a second fitting groove 22 provided on the back side of the peripheral surface of the sealing material placement recess 20, and generates a sealing surface pressure when compressed therebetween. The height of the valve portion 90 in the pipe diameter direction is referred to as the height H91 of the valve portion. FIG. 10 is a cross-sectional view in a direction orthogonal to the circumferential direction of the sealing material 9 before the insertion port 3 is inserted into the receiving port 2.

[0005] In addition, as a pipe joint using the sealing material 9 as described above, for example, it is described in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The material of the sealing member 9 has conventionally typically been an SBR (Styrene-Butadiene Rubber) material. However, in recent years, due to requirements such as oil resistance and chemical resistance, there has been a demand for sealing materials with high hardness such as NBR (Nitrile-Butadiene Rubber) materials. Here, when the hardness of the sealing member 9 increases, as shown in FIG. 11, when the sealing member 9 is compressed, high stress may occur at the contact portion A91 between the inner peripheral side of the sealing member 9 and the outer peripheral surface of the insertion port 3. FIG. 11 is a schematic of the stress analysis result by FEM (Finite Element Method) using the NBR material for the conventional sealing member 9 shown in FIG. 10 for verifying the generated stress in the sealed state. This high stress occurs in the process of inserting the insertion port 3 into the receiving port 2 to reach the sealed state (details will be described later). When the valve portion shown in FIG. 10 is pushed and expanded to the outer peripheral side as indicated by the arrow D91 in the figure, due to the high hardness of the sealing member 9, the bending and tensile stresses are particularly large on the inner peripheral side of the sealing member 9, and this stress remains in the sealed state.

[0008] In contrast, in order to relieve the generated stress, a seal material 9d obtained by improving the conventional seal material 9 by changing the height H91 of the valve portion 90d to be lower than the height H92 of the valve portion is shown in FIG. 12. As a result, the amount by which the valve portion 90d of the seal material 9d is pushed and expanded to the outer peripheral side, as shown by the arrow D92 in the drawing, is made smaller than that of the conventional seal material 9, so that high stress can be relieved. However, since the height H92 of the valve portion 90d is lower than the height H91 of the conventional valve portion (see FIG. 10), the compression allowance of the valve portion 90d in the sealed state decreases, and there is a risk that the watertightness deteriorates. Specifically, as shown in FIG. 13, when water pressure WP is applied from the inside of the pipe in the sealed state, the sealing surface pressure of the seal material 9d is lost, and a gap G is formed at the contact portion A92 between the outer peripheral side of the valve portion 90d and the sealing surface 23 of the receiving port 2, and there is a risk of water leakage from this gap G. FIG. 13 shows the result of a watertightness analysis performed on the improved seal material 9d.

[0009] As described above, the conventional seal material has a problem that it is difficult to satisfy both the requirements from the stress surface and the requirements from the watertightness in the sealed state, especially when the hardness of the seal material is high.

[0010] The present invention has been made in view of the above problems, and an object thereof is to provide a seal material that satisfies both the requirements from the stress surface and the requirements from the watertightness in a seal material compressed between the sealing surface of a receiving port and the outer peripheral surface of an insertion port.

Means for Solving the Problems

[0011] According to one aspect of the present invention, the seal material is an annular seal material made of an elastic material used for a pipe joint in which an insertion port formed at an end of a first pipe connected to each other is inserted into a receiving port formed at an end of a second pipe, a heel portion fitted into a fitting groove provided on the inner peripheral surface of the receiving port, a valve portion that is provided on the insertion direction side of the insertion port with respect to the fitting groove and has an inner diameter smaller than that of the fitting groove, and is sandwiched and compressed between the sealing surface of the receiving port and the outer peripheral surface of the insertion port and includes The valve part has a first convex part formed on the outer peripheral side and a second convex part formed on the inner peripheral side. In a cross-sectional view in a direction orthogonal to the circumferential direction of the sealing material in a state where the heel part is fitted into the fitting groove and the insertion port is not inserted into the receiving port, The first convex part and the second convex part have an arcuate outer contour line. A first radius of a first circle including the arcuate outer contour line of the first convex part is smaller than a second radius of a second circle including the arcuate outer contour line of the second convex part. The center of the first circle is located on the inner side in the pipe diameter direction of the seal surface of the receiving port and is included in the circumference of the second circle. A distance between the centers of the first circle and the second circle in the pipe axis direction (hereinafter referred to as the center distance) is smaller than a difference between the second radius and the first radius.

[0012] According to this, since the center of the first circle of the first convex part is included in the circumference of the second circle of the second convex part, the second convex part gets sufficiently close to the first convex part, and the deformation of the sealing material due to the valve part being pushed and expanded when the insertion port is inserted is suppressed, and the high stress generated on the inner peripheral side of the sealing material in the sealed state can be relaxed. Further, since the center distance is set to be smaller than the difference between the second radius and the first radius (hereinafter referred to as the radius difference), the center of the first circle of the first convex part and the center of the second circle of the second convex part are arranged to be substantially on the same straight line in the pipe diameter direction. Thereby, the sealing material efficiently generates a repulsive force in the valve part. As a result, the sealing material can obtain a sufficient seal surface pressure, and thus watertightness can be ensured.

[0013] In the cross-sectional view, the inner peripheral surface of the heel part and the inner peripheral surface of the second convex part of the sealing material according to the second invention are connected by an inclined surface. The inclined surface is inclined inward in the pipe diameter direction with respect to the insertion direction of the insertion port.

[0014] According to this, the inclined surface of the sealing material guides the tip of the insertion port inward in the pipe diameter direction when the insertion port is inserted, and reduces the insertion force of the insertion port by efficiently pushing and expanding the valve part to the outside of the pipe as the insertion port is inserted.

[0015] The sealing material according to the third invention has a center - to - center distance of zero in the cross - sectional view.

[0016] According to this, in the sealing material, the center of the first circle of the first convex portion and the center of the second circle of the second convex portion are arranged so as to be aligned on the same straight line in the pipe - diameter direction in the pipe - axis direction. As a result, the sealing material can efficiently generate a repulsive force in the valve and obtain a sufficient sealing surface pressure. As a result, the sealing material can improve the watertightness.

[0017] The sealing material according to the fourth invention has, in the cross - sectional view, the length of the chord connecting the intersection points of the first circle and the second circle being equal to the diameter of the first circle.

[0018] According to this, the cross - sectional area of the sealing material in the direction perpendicular to the pipe - diameter direction in the valve portion becomes large, so that the repulsive force of the sealing material can be increased, the watertightness can be improved, and the insertion force of the insertion port can also be reduced.

Advantages of the Invention

[0019] According to the present invention, in the sealing material compressed between the sealing surface of the receiving port and the outer peripheral surface of the insertion port, it is possible to satisfy both the requirement from the stress surface during compression and the requirement from the watertightness.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0021] Hereinafter, the sealing material 1 according to the embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description will not be repeated. Further, in the following description, terms such as "inside", "outside", "horizontal", and "vertical" that mean positions or directions may be used. These terms are used for convenience in order to facilitate the understanding of the embodiment and are not limited to the positions or directions in actual implementation.

[0022] Referring to FIG. 1, the configuration of the pipe joint 100 using the sealing material 1 according to an embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view of the pipe joint 100 using the sealing material 1.

[0023] As shown in FIG. 1, the pipe joint 100 includes an insertion port 3 formed at the end of the first pipe connected to each other, a receiving port 2 formed at the end of the second pipe into which the insertion port 3 is inserted, and an annular sealing material 1 made of an elastic material that seals between the receiving port 2 and the insertion port 3.

[0024] On the inner peripheral surface of the receiving port 2, a sealing material arrangement recess 20 where the sealing material 1 is arranged and a lock ring groove 24 located deeper than the sealing material arrangement recess 20 are formed over the entire circumference. A circumferentially spaced lock ring 25 is mounted in the lock ring groove 24. The insertion port 3 has a protrusion 31b formed over the entire circumference on the outer periphery of its tip portion 31 that can engage with the lock ring 25 from the back side of the receiving port 2. The tip portion 31 of the insertion port 3 is formed in a tapered shape with the outer peripheral surface of the protrusion 31b inclined inward in the pipe diameter direction with respect to the insertion direction of the insertion port. An elastic member 26 for centering the lock ring 25 is arranged between the lock ring 25 and the lock ring groove 24.

[0025] On the inner peripheral surface of the sealing material arrangement recess 20, a first fitting groove 21 (an example of a fitting groove), a sealing surface 23, and a second fitting groove 22 are connected in sequence from the opening end of the receiving port 2 toward the back side and are formed over the entire circumference. The sealing surface 23 is configured such that its inner diameter is smaller than the inner diameters of the first fitting groove 21 and the second fitting groove 22.

[0026] The sealing material 1 is compressed between the sealing surface 23 of the receiving port 2 and the outer peripheral surface of the insertion port 3 to generate a sealing surface pressure.

[0027] Next, referring to FIG. 2 in addition to FIG. 1, the configuration of the sealing material 1 will be described. FIG. 2 is a cross-sectional view in a direction orthogonal to the circumferential direction of the sealing material 1 alone not mounted on the pipe joint 100.

[0028] As shown in Fig. 2, the sealing material 1 has a heel portion 13 that is fitted into the first fitting groove 21, a valve portion 10 that is continuous with the heel portion 13 on the back side in the tube axis direction and is compressed between the sealing surface 23 of the receiving port 2 and the outer peripheral surface of the insertion port 3, a tapered portion 14 (an example of an inclined surface) that connects the inner peripheral surface of the heel portion 13 and the inner peripheral surface of the valve portion 10, and first to third recesses 16 to 18.

[0029] The valve portion 10 has an annular first valve portion 11 (an example of a first convex portion) formed on the outer peripheral side and an annular second valve portion 12 (an example of a second convex portion) formed on the inner peripheral side. The first valve portion 11 and the second valve portion 12 are formed over the entire circumference of the valve portion 10, the first valve portion 11 protrudes outward in the pipe diameter direction, and the second valve portion 12 protrudes inward in the pipe diameter direction. Hereinafter, in the same figure, the distance between the outer peripheral end of the first valve portion 11 and the inner peripheral end of the second valve in the pipe diameter direction is referred to as the first valve height H1.

[0030] As shown in the figure, the first valve portion 11 and the second valve portion 12 have an outer contour line with an arc shape, the arc shape of the first valve portion 11 includes a first circle 11c, and the arc shape of the second valve portion 12 includes a second circle 12c.

[0031] In the same cross-sectional view, the center C1 of the first circle is included within the circumference of the second circle 12c. Also, the first radius R1 of the first circle 11c is smaller than the second radius R2 of the second circle 12c.

[0032] Also, the center C1 of the first circle is located on the inner side in the pipe diameter direction of the sealing surface 23 of the receiving port 2. That is, the first valve portion 11 is disposed in the vicinity of the sealing surface 23.

[0033] The distance CD between the centers in the tube axis direction between the center C1 of the first circle and the center C2 of the second circle (hereinafter simply referred to as "center distance CD") is set to be smaller than the difference between the second radius R2 and the first radius R1 (hereinafter simply referred to as "radius difference"). Although details will be described later, this causes the center C1 of the first circle and the center C2 of the second circle to be arranged so as to be substantially on the same straight line in the pipe diameter direction.

[0034] The heel portion 13 is an annular member with a square cross-section in the cross-sectional view. The tapered portion 14 is an inclined surface that continuously reduces in diameter from the inner peripheral surface of the heel portion 13 to the inner peripheral surface of the second valve portion 12, and is formed over the entire circumference to connect the heel portion 13 and the valve portion 10. The heel portion 13 is generally formed of an elastic member having a higher hardness than the valve portion 10. 19 is a joint surface for integration. Hereinafter, the height of the first valve portion 11 in the direction orthogonal to the inclined surface of the tapered portion 14 is referred to as the second valve height H2.

[0035] The first recess 16, the second recess 17, and the third recess 18 are each arc-shaped in the cross-sectional view and are formed over the entire circumference in the valve portion 10. The first recess 16 is formed between the heel portion 13 and the first valve portion 11, the second recess 17 is formed between the first valve portion 11 and the second valve portion 12, and the third recess 18 is formed between the second valve portion 12 and the tapered portion 14.

[0036] Hereinafter, the operation of the sealing material 1 configured as described above will be described.

[0037] First, in addition to FIG. 2, with reference to FIGS. 3A to 3D, the process of inserting the insertion port 3 into the receiving port 2 and the operation related to the stress will be described. FIGS. 3A to 3D are longitudinal sectional views of the pipe joint 100 showing the joining procedure of the insertion port 3 to the receiving port 2.

[0038] From the state before the insertion of the insertion port 3 into the receiving port 2 shown in Fig. 3A, when the insertion port 3 is inserted as shown in Fig. 3B, the outer peripheral surface of the tip portion 31 of the insertion port 3 abuts against the inner peripheral surface of the tapered portion 14 of the sealing material 1, and the second valve portion 12 is pushed and expanded toward the inner peripheral back side of the receiving port 2 by the outer peripheral surface of the tip portion 31 (arrow D1 in the figure). Thereafter, as the insertion of the insertion port 3 proceeds as shown in Fig. 3C, since the tip portion 31 of the insertion port 3 is inclined toward the inside of the pipe in the insertion direction, the valve portion 10 receives acting forces in the pipe axis direction and the pipe diameter direction from the tip portion 31. As a result, by the insertion of the insertion port 3, the valve portion 10 is compressed in the pipe diameter direction and stretched in the pipe axis direction. Thereafter, as shown in Fig. 3D, the insertion is completed when the tip portion 31 passes through the second valve portion 12, the first valve portion 11 is pressed against the sealing surface 23, and the second valve portion 12 is pressed against the outer peripheral surface of the insertion port 3 to be sealed. Also, at this time, since the second valve portion 12 fits into the second fitting groove 22, the sealing material 1 is prevented from coming off on the front side of the pipe, and the sealing material 1 can stably ensure the sealing property.

[0039] In the process from the state of Fig. 3B to the state of Fig. 3C, since the center C1 of the first circle of the first valve portion 11 is included in the circumference of the second circle 12c of the second valve portion 12, that is, the first valve portion 11 and the second valve portion 12 approach each other in the pipe diameter direction, when the second valve portion 12 is pushed and expanded in the D1 direction shown in Fig. 3B, the amount by which the second valve portion 12 is pushed and expanded is smaller than that in the case of the conventional sealing material 9 (see Fig. 10). That is, the amount of bending and tension on the inner peripheral side of the sealing material 1 is smaller. As a result, the sealing material 1 can relieve the high stress generated on the inner peripheral side of the sealing material 1 in the sealing state of Fig. 3D.

[0040] Also, since the center C1 of the first circle of the first valve portion 11 is included in the circumference of the second circle 12c of the second valve portion 12, the center C1 of the first circle and the center C2 of the second circle approach each other, and the length SL of the chord connecting the intersection points of the first circle 11c and the second circle 12c can be increased. As a result, since the cross-sectional area in the direction orthogonal to the pipe diameter direction in the valve portion 10 becomes large, the sealing material 1 can increase the repulsive force in the valve portion 10.

[0041] However, if the center C1 of the first circle and the center C2 of the second circle approach each other too closely, the first valve height H1 and the second valve height H2 of the valve part 10 become small, resulting in a decrease in the compression allowance of the valve part 10. Therefore, the center C1 of the first circle approaches the center C2 of the second circle within a range where the sealing surface pressure can be ensured in the valve part 10.

[0042] Specifically, the first circle 11c and the second circle 12c are arranged such that as the centers C1 of the first circle and C2 of the second circle approach each other, the length SL of the chord becomes equal to the diameter of the first circle 11c (i.e., twice the first radius R1). This allows the sealing material 1 to obtain sufficient repulsive force due to the large cross-sectional area in the direction orthogonal to the pipe diameter direction in the valve part 10 and prevent a decrease in the compression allowance. As a result, the sealing material 1 can satisfy both the requirements from the stress surface and the requirements for watertightness.

[0043] In addition, in the process from the state of FIG. 3C to the state of FIG. 3D, the sealing material 1 makes it difficult for the second valve part 12 to come out of the second fitting groove 22 because the second radius R2 of the second circle 12c is larger than the first radius R1 of the first circle 11c and the inner diameter of the sealing surface 23 is larger than the inner diameter of the second fitting groove 22.

[0044] Next, referring to FIGS. 4A and 4B in addition to FIG. 2, the operation regarding watertightness will be described. FIGS. 4A and 4B are longitudinal sectional views of the pipe joint 100 in a state where the water pressure WP has not yet been applied in the watertightness analysis described above. FIG. 4A shows the case where the sealing material 1 according to the present invention is used, and the sealing material 1 in the sealed state is shown by a virtual line. FIG. 4B shows the case where a modified example of the sealing material 1, i.e., the sealing material 1d, is used for comparison with the sealing material 1 according to the present invention.

[0045] Note that, as shown in FIG. 5, for the watertightness analysis, it was assumed that a vertical misalignment BC occurred between the pipe axis of the receiving port 2 and the pipe axis of the insertion port 3, and the gap CL between the upper side of the receiving port 2 and the upper side of the insertion port 3 in the pipe joint 100 was the largest. At this time, as shown by the virtual line in FIG. 4A, due to the maximum gap CL, the valve portion 10 of the sealing material 1 is in a low compression state where it is not compressed much. The sealing material 1 needs to satisfy watertightness in this low compression state.

[0046] On the other hand, in the sealing material 1, in the range where the center - to - center distance CD is smaller than the radius difference (the difference between the second radius R2 and the first radius R1), the first circle 11c and the second circle 12c are arranged such that, as shown in the figure, the projection line L1 of the first circle 11c onto the pipe axis PC is within the range of the projection line L2 of the second circle 12c onto the pipe axis PC. That is, the first circle 11c is inside the second circle 12c in the pipe axis direction. Thereby, the center C1 of the first circle and the center C2 of the second circle are arranged to be aligned on substantially the same straight line L in the pipe diameter direction. Therefore, in the sealing material 1, the action point P1 of the repulsive force F1 by the first valve portion 11 on the sealing surface 23 and the action point P2 of the repulsive force F2 by the second valve portion 12 on the outer peripheral surface of the insertion port 3 are aligned on substantially the same straight line L in the pipe diameter direction, so that the repulsive forces F1 and F2 of the valve portion 10 can be increased. As a result, the sealing material 1 can obtain a sufficient sealing surface pressure, thereby ensuring watertightness.

[0047] Here, it is most preferable that the first circle 11c and the second circle 12c are arranged such that the center - to - center distance CD is such that the centers C1 of the first circle and C2 of the second circle overlap on the same straight line in the pipe diameter direction with respect to the radius difference. Thereby, the sealing material 1 can increase the repulsive forces F1 and F2 of the valve portion 10.

[0048] On the other hand, as shown in FIG. 4B, when the center-to-center distance CD is greater than the difference in radius, that is, as shown in the drawing, the projection line L1 of the first circle 11c onto the pipe axis PC is not within the range of the projection line L2 of the second circle 12c onto the pipe axis PC, that is, when the first circle 11c is not inside the second circle 12c in the pipe axis direction, the center C1 of the first circle and the center C2 of the second circle are displaced from each other in the pipe axis direction. As shown in FIGS. 10 and 12, in the conventional sealing materials 9 and 9d, since the center-to-center distance between the centers C91, C91d of the first circle and the centers C92, C92d of the second circle (not shown in FIGS. 10 and 12) is greater than the difference in radius, they are displaced from each other in the pipe axis direction as in the present modification 1d. When the valve portion 10 configured in this way is compressed as shown by the phantom line in FIG. 4B, the displacement amount in the pipe axis direction between the action point F11 of the repulsive force F11 of the first valve portion 11 on the sealing surface 23 and the action point F12 of the repulsive force F12 of the second valve portion 12 on the outer peripheral surface becomes large, so that the rotational moment M acting on the valve portion 10 becomes large. As a result, in the sealing material 1d, the repulsive forces F11 and 12 in the valve portion 10 are smaller than the repulsive forces F1 and F2 in the case of the sealing material 1, and there is a possibility that sufficient sealing surface pressure cannot be obtained.

[0049] Hereinafter, with reference to FIGS. 6 to 7, specific effects due to the actions described above will be described. FIG. 6 is an example of the stress analysis result obtained for the sealing material 1 for verifying the generated stress. FIG. 7 is an example of the water tightness analysis result obtained for the sealing material 1 for verifying the water tightness.

[0050] From FIG. 6, the bending and tensile stresses generated at the contact portion A1 between the inner peripheral side of the sealing material 1 and the outer peripheral surface of the insertion port 3 are relaxed in the inner peripheral side of the sealing material 1 as compared with the case of the conventional sealing material 9 shown in FIG. 11. Specifically, the maximum stress generated at the same portion A1 is significantly (47%) reduced compared to the case of the conventional sealing material 9.

[0051] Also, as shown in FIG. 7, at the contact portion A2 between the first valve portion 11 and the sealing surface 23 of the receiving port 2, even when water pressure is applied, there is no generation of a gap G (see FIG. 13) as seen in the conventional sealing material 9, and the sealing material 1 satisfies the requirements regarding watertightness.

[0052] Further, in the process of inserting the insertion port 3 into the receiving port 2 described above, when analyzing the insertion force required for insertion, although the maximum insertion force of the sealing material 1 slightly increases (by 4%) compared to the maximum insertion force of the conventional sealing material 1, it is almost equivalent and also satisfies the requirements regarding the insertion force.

[0053] From the above, the sealing material 1 can satisfy the requirements regarding the insertion force and can also reconcile the requirements regarding the generated stress and watertightness.

[0054] Note that the tapered portion 14 of the sealing material 1 does not have to be continuously formed from the heel portion 13 as shown in FIG. 2. That is, the sealing material 1 may be configured like the sealing material 4 shown in FIG. 8. FIG. 8 is a cross-sectional view in a direction orthogonal to the circumferential direction of the sealing material 4 which is a modified example of the sealing material 1 according to the embodiment of the present invention.

[0055] From FIG. 8, the sealing material 4 further has a third valve portion 43 and a fourth recess 49 with respect to the sealing material 1 described above. The tapered portion 44 of the sealing material 4 has a different shape from the tapered portion 14 of the sealing material 1. The third valve portion 43 is formed on the inner peripheral front side of the heel portion 13. The tapered portion 44 is an inclined surface that continuously reduces in diameter from the pipe inner side of the third valve portion 43 to the inner peripheral surface of the second valve portion 42, and by being formed over the entire circumference, it connects the third valve portion 43 and the second valve portion 42. The fourth recess is formed over the entire circumference of the sealing material 4 between the third valve portion 43 and the tapered portion 44.

[0056] Even if the sealing material 4 is configured as described above, since the first valve portion 11 and the second valve portion 12 are configured as described above, the sealing material 4 exhibits the same operational effects as the sealing material 1. Although not shown, specifically, in a stress analysis by FEM similar to the FEM analysis described above, the maximum stress was significantly reduced (by 26%) compared to the case of the conventional sealing material 9. Also, in the analysis result of watertightness, no gap G (see FIG. 13) as seen in the conventional sealing material 9 was formed. Furthermore, in the analysis result of the insertion force, the maximum insertion force was 6.7 kN, which was equivalent to the case of the conventional sealing material 9 (6.5 kNPa). That is, like the sealing material 1, the sealing material 4 can satisfy both the requirements from the stress surface and the requirements from watertightness.

[0057] As described above, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the gist thereof. The drawings schematically show each component mainly for easy understanding, and the thickness, length, number, interval, etc. of each illustrated component are different from the actual ones for convenience of drawing creation. Also, the material, shape, dimensions, etc. of each component shown in the above embodiments are examples and are not particularly limited, and various modifications can be made without substantially departing from the configuration of the present invention.

Explanation of Reference Numerals

[0058] 1 Sealing material 2 Receiver 3 Insertion port 10 Valve portion 11 First valve portion (first convex portion) 11c First circle C1 Center of the first circle R1 First radius 12 Second valve portion (second convex portion) 12c Second circle C2 Center of the second circle R2 Second radius 13 Heel portion 14 Taper portion (inclined surface) 16 First concave portion 17 Second recess 18 Third recess 20 Seal material placement recess 21 First fitting groove (fitting groove) 22 Second fitting groove 23 Sealing surface 24 Lock ring groove 25 Lock ring 26 Rubber material 30 Tip 100 Pipe joint

Claims

1. An annular sealing material made of an elastic material used for a pipe joint in which a socket formed at an end of a first pipe connected to each other is inserted into a socket formed at an end of a second pipe, a heel portion fitted into a fitting groove provided on the inner peripheral surface of the socket, a valve portion sandwiched and compressed between a sealing surface of the socket provided on the insertion direction side of the socket with respect to the fitting groove and having a smaller inner diameter than the fitting groove and the outer peripheral surface of the socket comprising, the valve portion has a first convex portion formed on the outer peripheral side and a second convex portion formed on the inner peripheral side, in a cross-sectional view in a direction orthogonal to the circumferential direction of the sealing material in a state where the heel portion is fitted into the fitting groove and the socket is not inserted into the socket, the first convex portion and the second convex portion have an arcuate outer contour line, a first radius of a first circle including the arcuate outer contour line of the first convex portion is smaller than a second radius of a second circle including the arcuate outer contour line of the second convex portion, the center of the first circle is located on the inner side in the pipe diameter direction of the sealing surface of the socket and is included in the circumference of the second circle, a distance between the centers of the first circle and the second circle in the pipe axis direction (hereinafter, center distance) is smaller than a difference between the second radius and the first radius The sealing material is characterized by that.

2. In the cross-sectional view, the inner peripheral surface of the heel portion and the inner peripheral surface of the second convex portion are connected by an inclined surface, The inclined surface is inclined inward in the pipe diameter direction with respect to the insertion direction of the socket The sealing material according to claim 1, characterized in that.

3. The center distance in the cross-sectional view is zero The sealing material according to claim 1 or claim 2, characterized in that.

4. In the cross-sectional view, the first circle and the second circle are such that the length of a chord connecting the intersection points of the first circle and the second circle is equal to the diameter of the first circle The sealing material according to claim 1 or claim 2, characterized in that.

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