JP2014062609A - Shaft seal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft seal device which achieves good balance between sealability and driving when a temperature of a working fluid is low.SOLUTION: A shaft seal device is composed of: a stem; a packing box; a gland packing; and a packing presser. In the shaft seal device, a contact pressure is applied to the gland packing by tightening the packing presser with a bolt. The gland packing is composed of a hull member made of a soft resin material and a core member made of a hard resin material. The hull member made of the soft resin material has the sealability, and the core member made of the hard resin material transmits the contact pressure.

Description

  The present invention relates to a shaft seal device.

  In the valve, a shaft seal device is used in order to prevent leakage from the stem portion (see Patent Document 1). As shown in FIG. 6, the shaft seal device includes a stem 2, a packing box 3, a gland packing 9, and a packing presser 5.

  The gland packing 9 is a component that maintains a sealing property during driving, and is made of a resin material that is deformed when pressure is applied to the surface. The gland packing 9 expands in the lateral direction by applying a surface pressure by the packing presser 5, and adheres to the stem 2 and the packing box 3 to obtain a sealing property. In order to obtain a sealing property, a plurality of gland packings 9 are used as shown in FIG. If the surface pressure is too large, the operating resistance increases and driving becomes difficult. The surface pressure during assembly is managed to maintain a balance between sealing performance and drive.

  Further, it is known that a gland packing of two or more different materials, for example, a gland packing 9a made of a hard resin and a gland packing 9b made of a soft resin are used in an overlapping manner to improve the sealing performance and driving.

JP 2002-181197 A

  When the working fluid becomes low temperature, a leak occurs because the difference in shrinkage rate due to material properties between the components of the shaft seal device is large. For example, when the working fluid is hydrogen, leakage occurs when the temperature difference from the environment where the valve equipped with the shaft seal device is installed exceeds 50 ° C. As a countermeasure, the bolt 6 is tightened, but the creep of the upper gland packing 9 is intense, and the surface pressure is not transmitted to the lower gland packing 9, so that the leak is not eliminated.

  A shaft seal device including a stem 2, a packing box 3, a gland packing 4 formed of a shell member made of a soft resin material and a core member made of a hard resin material, and a packing presser 5 is used. The gland packing 4 is a resin material with a soft outer skin and has a sealing property, and transmits a surface pressure with a resin material with a hard core.

Action

According to the present invention, the surface pressure is transmitted from the packing presser 5 to the lower gland packing 4 by retightening, and all the gland packings 9 are spread laterally from the upper part to the lower part, so that the stem 2 and the packing box 3 are in close contact with each other. Get. The seal and drive are well balanced.

  Even in an operating environment where the working fluid is at a low temperature, a good balance between sealing performance and driving can be obtained.

  Furthermore, even if the number of gland packings is reduced and the shape is reduced, sealing performance and ease of driving can be obtained, so that the volume of the packing box can be reduced, and the shape of the entire shaft seal device is also reduced.

  In addition, since there is only one type of gland packing used in the shaft seal device, there is no error in the type of gland packing, and assembly is facilitated.

The block diagram which shows typically the structure of the shaft seal apparatus in embodiment of this invention Perspective view of the gland packing of the present invention (most desirable form) Sectional view of the gland packing of the present invention (most desirable form) Sectional view of the gland packing of the present invention (another form) The perspective view of the gland packing of this invention (another form) The block diagram which shows typically the structure of the shaft seal apparatus using two types of conventional gland packings

Embodiments of the present invention will be described below.

In the shaft sealing device including the stem 2, the packing box 3, the gland packing 4, and the packing presser 5 shown in FIG. 1, the outer shell made of a soft resin material of the gland packing 4 as shown in FIGS. The member 7 is made of UPE, PTFE or thermoplastic elastomer, and the core member 8 made of a hard resin material is formed in a double structure using super engineering plastics such as PEEK and PPS (except PTFE).

The stem 2 moves valves such as a globe valve and a butterfly valve. The globe valve slides and the butterfly valve rotates. In addition to valves, it is also used for pumps and transmits driving force by rotating and reciprocating.

The packing box 3 is a portion that houses one or more gland packings at a location where the inner diameter changes at a through hole where the inner diameter changes midway. In order to store a large number of gland packings and attach the packing presser 5, the distance from the larger diameter of the penetrating term to the position where the inner diameter changes is larger than the inner diameter and is provided in a deep place.

As shown in FIG. 2, the gland packing 4 has a donut shape with a quadrangular cross section. The inner diameter surface is in close contact with the stem 2 surface and the outer diameter surface is in close contact with the side surface of the packing box 3. To do. The inner diameter surface slides against the surface of the stem 2 as the stem moves. The outer diameter surface does not move relative to the side surface of the packing box 3. The cross-sectional shape does not have to be a square, and may be, for example, a parallelogram or another shape. When assembling, the gland packing 4 is installed by pushing the gland packing 4 from the larger penetrating diameter to the part where the inner diameter changes. On the other hand, when repairing and replacing, the gland packing 4 is taken out from the part where the inner diameter changes. After that, a new gland packing 4 is pushed in and installed. There is one type of gland packing 4. Because of the excellent characteristics, desirable sealing performance and drivability can be obtained even with a smaller number than the conventional one.

For the core member 8 made of a hard resin member of the gland packing 4, a member having a large elastic modulus with a large stress against strain is selected, a tensile strength of 49 MPa or more, a bending elastic modulus of 2.5 GPa or more, and a heat resistance temperature of 150 ° C. or more. Super engineering plastic is desirable as the core member 8 of the present invention because of its high mechanical strength including elastic modulus. Among them, PEEK and PPS are most desirable because they are strong against creep.

As the outer skin member 7 made of a soft resin member of the gland packing 4, a member having a smaller elastic modulus than the core member 8 is selected. It is desirable for sealing performance to be largely distorted by stress. Since the surface of the inner diameter of the gland packing 4 slides with respect to the movement of the stem, a material with good slidability is desirable. UPE, PTFE or thermoplastic elastomer is a material excellent in slidability and is desirable as the outer skin member 7.

As long as it has sealing properties and ease of driving, the outer skin member 7 may be made of another resin material. The core member 8 may be made of another resin material as long as the surface pressure is transmitted well. Even in that case, the core member 8 must be made of a material harder than the outer skin member 7. For example, when the outer skin member 7 is PTFE, the core member 8 must be a material harder than PTFE.

As shown in FIG. 3, integral molding is used to form the outer skin member 7 and the core member 8 in a two-layer structure. For example, after the ring-shaped core member 8 is molded with PEEK having a high melting point, the core member 8 is floated and installed in a predetermined container using a needle, and the outer skin member 8 is integrally molded by filling the surrounding with a low melting point UPE. Super engineering plastic, which is a hard material, has a high heat resistance temperature, and therefore it is easy to form the outer skin member 7 on the outer side after the core member 8 is formed. The position of the needle that floats the core member 8 is set to a location that is not the surface of the inner surface of the gland packing 4 and the surface of the outer surface.

Next, as shown in FIG. 4, two or more sheet-like members may be bonded to each other, or after forming a string made of the core member 7 and the outer skin member 8 as shown in FIG. 5. Alternatively, it may be formed by cutting into a ring shape. A method not shown here may be used. Among them, the gland packing 4 formed by integral molding is most desirable because the surface pressure is evenly transmitted to the outer skin material 7. When two or more sheet-like members are bonded together vertically, or when a string is cut and then cut into a ring shape, the surface pressure may vary due to the cut and may leak from that portion.

The packing presser 5 is a circular pipe having a flange on one side. The shape on the side in contact with the gland packing 4 is the same as that of the gland packing. If the shape is small, the surface pressure cannot be evenly transmitted to the gland packing, and desirable sealability and driveability cannot be obtained. When the shape is large, the surface pressure is transmitted to the gland packing 4 and the gland packing spreads in the lateral direction. When the seal 2 is in close contact with the stem 2 and the packing box 3 to obtain the sealing performance, the packing presser 5 becomes an obstacle, and desirable sealing performance and driving performance are obtained. Cannot be obtained. The plunge has a through hole. A surface pressure is applied to the gland packing 4 by passing the bolt 6 and inserting it into a screw hole cut in the body of the shaft seal device.

DESCRIPTION OF SYMBOLS 1 Shaft seal device 2 Stem 3 Packing box 4 Gland packing formed with a skin member and a core member 5 Packing retainer 6 Bolt 7 Skin member 8 Core member 9 Gland packing 9a Gland packing made of hard resin 9b Gland packing made of soft resin

Claims (5)

Packing box,
Stem,
Packing presser,
A shaft seal device comprising: an outer skin member made of a soft resin material; and a gland packing formed of a core member made of a hard resin material.   The shaft seal device according to claim 1, wherein the gland packing is formed by integral molding.   The outer skin member made of the soft resin material is made of UPE, PTFE, or a thermoplastic elastomer, and the core member made of the hard resin material is provided with a gland packing made of super engineering plastic (excluding PTFE) such as PEEK, PPS. Alternatively, the shaft seal device according to claim 2.   A valve comprising the shaft seal device according to any one of claims 1 to 3.   A gland packing used in the shaft seal device according to any one of claims 1 to 3.

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