JPH04131583A - Sealing mechanism for mechanical joint - Google Patents

Abstract

PURPOSE:To keep surface pressure between a seal member and a joint body desirable by constructing sealing mechanism provided with a seal member interposed between the end part inner peripheral surface of a joint body and the outer peripheral surface of a pipe body in such a way as to change the storage space volume of the seal member according to the change of temperature. CONSTITUTION:A pressure ring 2 is screwed with the end part of a joint body 1, and a seal member 3 is fixed in close contact with the inner peripheral surface 1a of the joint body 1. and the outer peripheral surface of a pipe body A so as to prevent liquid or gas in the pipe body A from leaking outside. A pair of annular retainers 6, 7 and an annular transforming member 8 are interposed between the inner peripheral surface 2b of the pressure ring 2 and the seal member 3. The retainer 7 is in contact with the end face of the seal member 3, and the storage space volume of the seal member 3 is changed by the axial movement of the retainer 7. This results in suppressing or preventing the lowering of sealing performance even with the contraction of the seal member 3 so as to improve the reliability of the joint.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a mechanical joint for connecting pipe bodies such as gas pipes and water pipes, and in particular to a mechanical joint for connecting pipe bodies such as gas pipes and water pipes. The present invention relates to a sealing mechanism of the mechanical joint that achieves airtightness and watertightness between pipe bodies.

[Prior Art] As a mechanical joint as described above, one having a configuration as shown in FIG. 10 is known. This mechanical joint is
The joint body 1 which is fitted onto the outside of the tube body A and the press ring 2 are screwed together, and a sealing member 3 made of a rubber material is interposed between the inner peripheral surface of the joint body 1 and the outer peripheral surface of the tube body A. It's full. In order to bring the seal member 3 into close contact with the inclined inner circumferential surface of the joint body 1 and the outer circumferential surface of the tube body A, the end surface 3a of the seal member 3 and the press ring 2 are
An annular retainer 4 is provided between the radial inner circumferential surface 2b of the
is interposed. This retainer 4 has a small coefficient of friction with the press ring 2 (and by providing the lever retainer 4, the rotation of the press ring 2 is prevented from being transmitted to the sealing member 3. An inner circumferential surface 2a is formed which expands in diameter toward the joint body 1 side, and a lock ring 5 is interposed between this inner circumferential surface 2a and the outer circumferential surface of the tube body A.

This lock ring 5 bites into the outer peripheral surface of the tube A to prevent the tube A from being pulled out when some pulling force (arrow X) is applied to the tube A.

As mentioned above, in conventional mechanical joints, the joint body 1
When the screwing of the press ring 2 and the press ring 2 is completed, the sealing member 3 is stored in a storage space of a certain capacity formed by the joint body 1, the retainer 4, and the pipe body A, thereby forming a sealing mechanism. was.

[Problems to be Solved by the Invention] However, in the conventional sealing mechanism of the mechanical joint as described above, the sealing member 3 has a storage space of a certain capacity that is formed when the screwing of the joint body 1 and the press ring 2 is completed. Therefore, there was a problem in that the sealing member 3 made of a rubber material could not cope with contraction or expansion due to temperature changes. In other words, when the seal member 3 contracts within a storage space of a certain capacity as described above, the surface pressure between the seal member 3 and the inner circumferential surface of the joint body 1 decreases, resulting in a problem that the sealing performance is reduced. On the other hand, if the seal member 3 attempts to expand in the storage space, the seal member 3 will be pressed against the inner circumferential surface of the joint body 1 due to excessive pressure. There is a problem in that the deterioration of the sealing member 3 is accelerated at the contact area, especially near the end 3b of the storage space.In particular, the inner peripheral surface of the joint body 1 is coated with a synthetic resin such as polybutene to prevent galvanic corrosion. When a synthetic resin film is formed, the synthetic resin film side also expands and a larger surface pressure is generated, and the decrease in durability due to deterioration of the seal member 3 becomes more significant.

The invention was made in view of the above circumstances,
In a mechanical joint sealing mechanism in which a sealing member is interposed between the inner circumferential surface of the end of the joint body to which the press ring is screwed and the outer circumferential surface of the pipe body, even if the sealing member expands or contracts,
It is an object of the present invention to provide a sealing mechanism in which the surface pressure between the sealing member and the joint body is maintained well.

[Means for Solving the Problems] A seal mechanism for a mechanical joint according to a first invention that achieves the above object is characterized in that the capacity of the storage space of the seal member is changed in accordance with temperature changes. .

A second aspect of the present invention is characterized in that a shape memory alloy is interposed between the press ring and the seal member to change the capacity of the storage space in accordance with temperature changes.

A sealing mechanism for a mechanical joint according to a third aspect of the invention that achieves the above object is characterized in that the capacity of the storage space for the sealing member is variable in accordance with expansion and contraction of the sealing member.

A sealing mechanism for a mechanical joint according to a fourth invention discloses a specific configuration of the third invention, in which an elastic member is interposed between the press ring and the sealing member, thereby increasing the capacity of the storage space for the sealing member. is variable.

[Function] According to the first invention, even if the sealing member expands or contracts due to a temperature change, the capacity of the storage space of the sealing member also expands or contracts in accordance with the temperature change, so that the sealing member and the joint The contact pressure between the bodies hardly changes.

According to the second invention, the shape memory alloy deforms to expand the storage space as the temperature rises, and deforms to narrow the storage space as the temperature falls, so that the shape memory alloy can be sealed even when temperature changes occur. The surface pressure between the member and the joint body is kept almost constant.

According to the third invention, since the capacity of the storage space for the seal member is variable by the expansion and contraction of the seal member,
This prevents the surface pressure between the seal member and the joint body from becoming abnormally large due to expansion, and conversely from decreasing the surface pressure due to contraction.

According to the fourth invention, the sealing member expands to press the elastic member and expand the storage space thereof.

Further, when the sealing member contracts, the elastic member returns to its original position following the contraction, thereby narrowing the storage space for the sealing member.

[Embodiments] Several embodiments of the sealing mechanism of a mechanical joint according to the invention will be described below with reference to the drawings.

In the sealing mechanism of the mechanical joint shown in FIG. 1, parts corresponding to those shown in FIG. 10 are given the same reference numerals, and some explanations are omitted. That is, even in the sealing mechanism of the mechanical joint shown in FIG.
By screwing the press ring 2 onto the end of the joint body 1,
A resilient sealing member 3 made of, for example, a rubber material is brought into close contact with the inclined inner circumferential surface 1a of the joint body 1 and the outer circumferential surface of the tube body A, thereby preventing the liquid or gas inside the tube body A from leaking to the outside. I have to.

Between the radial inner peripheral surface 2b formed on the press ring 2 and the radial end surface 3a of the seal member 3,
A pair of annular retainers 6.7 and a similarly annular transformation member 8 arranged between these retainers 6.7 are interposed.

The retainer 6 is in contact with the inner peripheral surface 2b of the press ring 2.

The retainer 6 is made of a material that has a small coefficient of friction with the press ring 2, and therefore the rotation of the press ring 2 is hardly transmitted to the transformation member 8.

The retainer 7 is in contact with the end surface of the seal member 3, and therefore, the capacity of the storage space of the seal member 3 changes as the retainer 7 moves in the axial direction.

The annular transformation member 8 is made of a shape memory alloy, and the second
As shown in the figure, it is formed in the shape of a disc spring with a truncated conical external shape. In this way, the height of the transformation member 8 made of the shape memory alloy changes as shown in FIG. 3 in response to changes in temperature. For example, the transformation member 8, which has a height hO as shown by a solid line at room temperature, has a height hO as shown by a dashed line when the temperature rises to a predetermined temperature higher than room temperature.
1 (ho>hl), and when the temperature drops to a predetermined temperature below room temperature, the height h2 increases as shown by the two-dot chain line.
(hO<h2). The transformation start temperature when the temperature rises and the transformation start temperature when the temperature falls do not necessarily match, and therefore the transformation member 8 does not change its height in a predetermined temperature range around room temperature even if the temperature changes. That is, the height of the transformation member 8 does not change in accordance with changes in temperature in all temperature ranges.

Further, it is preferable that the amount of change in the height of the transformation member 8 due to a temperature change is smaller than the amount of change in the axial direction of the seal member 3 due to the same temperature change.

As a shape memory alloy used for such a transformation member 8, for example, a Ti-Ni alloy or the like is employed.

In the mechanical joint sealing mechanism constructed as described above, the height of the transformation member 8 decreases when the temperature becomes high, and the height of the transformation member 8 increases when the temperature decreases. Therefore, the position of the retainer 7 moves in the axial direction in response to temperature changes, and the capacity of the storage space for the seal member 3 is expanded or contracted. That is, the seal member 3 can move the retainer 7 and expand as the temperature rises, but even if it contracts as the temperature drops, it is pressed against the retainer 7, so there is no gap between the seal member 3 and the retainer 7. Does not occur.

For example, when the retainer 7 is placed at the position shown by the solid line in FIG. 1 at room temperature, when the temperature rises to a predetermined temperature higher than room temperature, the difference in height of the transformed member 8 at this predetermined temperature and at room temperature is hO- It becomes possible to move in the direction away from the sealing member 3 by hl. That is, the storage space for the seal member 3 increases by hO-hl in the axial direction, and therefore the seal member 3 can also expand by hO-hl in the axial direction as the temperature rises. Conversely, when the temperature of the retainer 7 decreases to a predetermined temperature below room temperature, the transform member 8 moves the retainer 7 in a direction approaching the seal member 3 by the difference hO−h2 between the heights of the transform member 8 at the predetermined temperature and at room temperature. be moved. That is, the storage space for the seal member 3 is hO-h in the axial direction.
It becomes smaller by 2. Therefore, even if the seal member 3 contracts due to a decrease in temperature, the seal member 3
can be pressed with a pressure greater than a predetermined pressure.

According to the seal mechanism of the mechanical joint as described above, even if the seal member 3 expands in response to a rise in temperature, the surface pressure between the seal member 3 and the inner peripheral surface of the joint body 1 will not increase abnormally. Moreover, even if the sealing member 3 contracts as the temperature decreases, the surface pressure will not drop significantly and the sealing performance will not be impaired.

The sealing mechanism of the mechanical joint shown in FIG. 4 has substantially the same construction as that shown in FIG. 1 above.

However, the aspect of the transformation member 18 made of a shape memory alloy is different from that of the transformation member 8, and accordingly, a retainer 16 is employed in place of the retainer 6. Other parts are the same as those in FIG. 1, and corresponding parts are denoted by the same reference numerals and detailed explanations thereof are omitted.

The transformation members 18 of this embodiment constitute a set of four having the same shape, and each transformation member 18 is arranged at intervals of 90° in the circumferential direction. As shown in FIG. 6, the individual transformation members 18 are formed with a V-shaped cross section, and as the temperature rises, the depth of the groove becomes shallower, and as the temperature decreases, the depth of the groove becomes deeper. As shown in FIG. 5, the annular retainer 16 has 90
Recesses 16a of the same shape are formed at intervals of .degree., and the transformation member 18 is placed in each of these recesses 16a.

Due to the above-described transformation, each of the transformation members 18 has a recess 16a...
・Change the amount of protrusion from. Therefore, the position of the retainer 7 changes in the axial direction, and the capacity of the storage space of the seal member 3 changes.

The process of changing the capacity of the storage space due to the transformation of the transformation members 18 is the same as that shown in FIG. 1 above, and detailed explanation thereof will be omitted here.

Note that the shape of the transformation members arranged at intervals in the circumferential direction like the transformation members 18 does not necessarily have to have a V-shaped cross section as shown in FIG. It may have a spiral shape, that is, it may have a coil spring-like appearance.

The seal mechanism of the mechanical joint shown in FIG. 7 includes a transformation member 28 made of a shape memory alloy in place of the transformation member 8 in the one shown in FIG. As shown in FIG. 8, this transformation member 28 is integrally formed with a plurality of protrusions 28b that protrude in the radial direction and are arranged at equal intervals in the circumferential direction on the outer peripheral edge of the annular seal member abutting portion 28a. A transformed portion 28c is formed by bending each tip of these projecting pieces 28b into a V-shape. In this transformation member 28, the bending angle of the transformation portion 28c and the protruding piece 28b changes according to temperature changes. That is, as the temperature increases, the bending angle of the transformed portion 28c and the protruding piece 28b becomes smaller, as shown by the dashed line in FIG.
The capacity of the storage space for the seal member 3 is increased.

Furthermore, when the temperature becomes low, the bending angle of the transformed portion 28c and the protruding piece 28b becomes large, and the capacity of the storage space of the seal member 3 becomes small. Even if the member 3 expands, the surface pressure between the seal member 3 and the inner circumferential surface 1a of the joint body 1 will not become abnormally large, and even if the seal member 3 contracts due to low temperature, the surface pressure will not increase abnormally. The pressure does not decrease and the sealing performance does not deteriorate.When the above-mentioned transformation member 28 is used, the retainer 7 in FIGS.
is not necessary. The other parts shown in Fig. 7 are the same as those in Fig. 1, and corresponding parts are given the same reference numerals.
A detailed explanation thereof will be omitted.

FIG. 9 shows a sealing mechanism for a mechanical joint according to another invention. Similar to the sealing mechanism shown in FIG. 1, this sealing mechanism is also similar to the sealing mechanism shown in FIG.
A sealing member 3 is interposed between the outer circumferential surface of the tube body A and the outer circumferential surface of the tube body A. In this sealing mechanism as well, the inner peripheral surface 2b of the press ring 2 and the sealing member 3
A pair of annular retainers 6.7 and a transformation member 38 disposed between the retainers 6.7 are interposed between the end surfaces 3a of the retainers 6.7. However, the transformation member 38 of this sealing mechanism is not a shape memory alloy (it is an elastic material, that is, a coil spring here).The other configuration of the sealing mechanism shown in FIG.
There is no difference from what is shown in the figure.

In the seal mechanism of the mechanical joint constructed as described above, when the seal member 3 expands, the transformation member 38, that is, the coil spring is compressed by being pushed by the seal member 3, and the position of the retainer 7 moves toward the retainer 6 side. In other words, the capacity of the storage space for the seal member 3 is expanded as the seal member 3 expands. Therefore, even if the seal member 3 expands, the surface pressure between the seal member 3 and the inner circumferential surface 1a of the joint body 1 does not increase significantly. Further, when the seal member 3 contracts, the retainer 6 remains in contact with the end surface 3a of the seal member 3 and moves away from the retainer 6 due to the return force of the coil spring serving as the transformation member 38. That is, as the seal member 3 contracts, the storage space capacity of the seal member 3 is reduced. Therefore, even if the seal member 3 contracts, the seal member 3 and the inner peripheral surface 1 of the joint body 1
The sealing performance will not be impaired due to a significant decrease in the surface pressure between a.

Note that the type and shape of the elastic material used as the transformation member 38 can be arbitrarily selected.

The sealing mechanisms of mechanical joints according to all of the inventions described above can also be applied to cases where a synthetic resin coating made of polybutene or the like is formed on the inner peripheral surface of the joint body 1 to prevent electrolytic corrosion.

[Effects of the Invention] According to claims 1 to 4, even if the sealing member 3 contracts, the surface pressure between it and the inner circumferential surface of the joint body 1 is small (reducing or preventing a decrease in sealing performance). This improves the reliability of the joint.Furthermore, even if the seal member expands, the surface pressure between the seal member and the inner circumferential surface of the joint body does not become abnormally large, so the joint body and joint body of the seal member This has the effect of preventing accelerated deterioration at the contact area and providing high durability.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a main part showing the sealing mechanism of the mechanical joint according to the invention, Fig. 2 is a perspective view of the transformation member, Fig. 3 is an explanatory diagram showing the transformation state of the transformation member, and Fig. 4 is another embodiment. Fig. 5 is a front view of the retainer, Fig. 6 is a perspective view of the transformation member, Fig. 7 is an enlarged longitudinal sectional view of the main part of another embodiment, and Fig. 8 is the transformation member. 9 is a longitudinal sectional view showing a sealing mechanism of a mechanical joint according to another invention, and FIG. 10 is a longitudinal sectional view of a conventional example. 1... Joint body 2... Push ring 3... Seal member 8, 18.28... Transformation member (shape memory alloy) 38.
...Transformation member (elastic member) No. 91 Patent applicant Nippon Steel Pipe Fittings Co., Ltd.

Claims (4)

[Claims] (1) In a mechanical joint sealing mechanism in which a sealing member is interposed between the inner circumferential surface of the end of the joint body to which the push ring is screwed and the outer circumferential surface of the pipe body, the capacity of the storage space of the sealing member is determined by the temperature. A sealing member for a mechanical joint, characterized in that it changes according to changes. (2) A sealing mechanism for a mechanical joint according to claim 1, characterized in that a shape memory alloy is interposed between the press ring and the sealing member to change the capacity of the storage space in accordance with temperature changes. (3) In a mechanical joint sealing mechanism in which a sealing member is interposed between the inner circumferential surface of the end of the joint body to which the press ring is screwed and the outer circumferential surface of the pipe body, the capacity of the storage space for the sealing member is A sealing mechanism for a mechanical joint characterized by being variable according to the expansion and contraction of a sealing member. (4) The sealing mechanism for a mechanical joint according to claim 3, wherein the capacity of the storage space is made variable by interposing an elastic member between the pushing ring and the sealing member.