JPH04151084A - Shaft sealing part structure - Google Patents

Abstract

PURPOSE:To facilitate exchange of a gland packing by mounting a shaft support member on a casing, holding a packing press member between the shaft support member and a gland packing, and forming a through-hole, in which a jig having a screw part is inserted and which allows the tip of the jig to make contact with the casing, in the shaft support member. CONSTITUTION:A through-hole 1a through which a valve stem 3 is inserted is formed in the wall body of a valve box 1. A gland packing 6 is contained on a packing support ring 5 of the through-hole 1a. The gland packing 6 is supported through a packing press member by means of a disc spring (a resilient member) 9, a disc spring support member 10 (a packing press member), and a press bolt 11 (a holding member). To support the valve stem 3, a valve stem support member 12 (a shaft support member) is mounted by means of a mounting bolt 16 (a mounting member). A tap hole (g) (a screw hole) in which a jig 21 is inserted is formed in the valve stem support member 12. As a result, when the gland packing is exchanged, the gland packing can be rapidly exchanged without breakage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shaft seal structure for sealing between a casing and a shaft penetrating portion passing through the casing.

In the following description, a valve, particularly a globe valve, is taken up as a typical example of a device having such a shaft seal structure, but the present invention has a shaft seal structure that has the following disadvantages. Insofar, it is also applicable not only to valves but also to rotating machines, such as pumps, for example.

[Prior Art] Generally, the other end of a valve stem having a valve body at one end extends outside through a valve box or casing, and is operated via an operating part such as a handle provided at the other end of the valve stem. A valve device of the type that adjusts the opening degree or opens and closes a valve body is provided with a shaft sealing portion in a penetrating portion where a valve stem passes through a valve body.

This shaft sealing part is equipped with a gland packing that is disposed in an annular space defined by the inner surface of the valve box and the outer surface of the valve stem penetration part, that is, a packing box, for sealing. In order to achieve this, the gland packing must be pressed against the above-mentioned surface defining the annular space. That is, a gland packing plate is provided above the gland packing, and the gland packing is compressed and tightened by pressing the packing holding plate against the gland packing in the axial direction with the packing holding bolt via the gland packing bushing. , to ensure sealing.

In a valve device having such a shaft seal structure, when replacing the gland packing, loosen the nut of the packing holding bolt to release the tightening force of the gland packing, and then
The packing press plate was shifted upward, and the resulting space was used to insert a special packing removal jig into the annular space from a diagonal ram to remove the gland packing stacked in multiple stages in order from the top.

[Problems to be Solved by the Invention] However, with the conventional shaft seal structure described above, when replacing the gland packing, it is necessary to pull out a plurality of gland packings individually. It took a lot of time.

In addition, graphite is often used as the material for gland packing, but especially when graphite is used, the shape of the gland packing tends to collapse when it is removed, and the gland packing comes out broken in pieces. Sometimes it even comes.

The gland packing itself is something to be replaced, so it may not be a problem if it gets damaged, but fragments will form as a result of the damage. If a fragment occurs, it is extremely difficult to check the inside of the packing box because there is a packing press plate etc. at the entrance of the packing box, so the fragment will remain as a residue inside the packing box at the shaft sealing part and reduce the sealing effect. It may be hindered.

Furthermore, since the gland packing plate is directly pressed by the nut of the gland packing bolt, if the volume of the gland packing decreases due to wear between it and the valve stem, the tightening force against the gland packing will suddenly decrease. There is also a possibility that the seal cannot be maintained.

Accordingly, a main object of the present invention is to provide a shaft seal structure configured such that the gland packing can be easily replaced without substantially causing damage to the gland packing.

Another object of the present invention is to provide a shaft seal structure that is not only configured as described above, but also does not substantially reduce the tightening force due to wear of the gland packing.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a shaft seal for sealing between a wall of a casing and a penetrating portion of a shaft passing through the wall. The structure includes a packing box formed on the wall, a packing support ring disposed within the packing box and surrounding the penetration part, and a packing support ring disposed in the packing box surrounding the penetration part. a gland packing supported by a ring; a shaft support member screwed onto the shaft and mounted on the casing to support the shaft; a mounting member for mounting the shaft support member on the casing; a packing pressing member surrounding and disposed between the shaft supporting member and the gland packing, and a holding member holding the packing pressing member in contact with the gland packing; A screw hole is formed through the casing for receiving a jig having a threaded portion and allowing the tip of the jig to come into contact with the wall of the casing.

Further, the shaft seal structure described above can further include an elastic member disposed in engagement with the gland packing member in order to apply a tightening force to the gland packing.

[Operation] When you want to replace the gland packing, first remove the mounting member.Since the shaft support member is screwed onto the shaft,
Even if the mounting member is removed, it remains in the screwed state.

Next, after releasing the holding member of the packing holding member and hence the gland packing, insert the jig into the screw hole of the shaft support member and screw it in so that its tip comes into contact with the wall of the casing. When the jig is screwed in further, since the shaft support member is screwed onto the jig, the shaft support member and the shaft screwed thereon move upward in the embodiment.

At this time, the gland packing support ring, the gland packing, and the packing pressing member move upward together with the shaft, and as a result, the gland packing is removed from the packing box. To remove this, simply replace the gland padskin that came out.

If an elastic member is provided, this elastic member:
When the shaft seal structure is assembled, it usually engages with the packing pressing member to apply a tightening force to the gland packing, contributing to reliable sealing.

[Embodiments] Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which the same reference numerals indicate the same or corresponding parts. As mentioned above, the case where the present invention is applied to the shaft seal structure of a globe valve will be described, but the present invention can also be applied to other types of valves and shaft seal structures of rotating machines such as pumps. Applicable.

Referring to the drawings, FIG. 1 shows, in cross section, the overall structure of a globe valve V having a shaft seal structure according to the present invention.

The globe-shaped valve V has a valve box or casing 1, and inside the valve box, there is a cavity d having an annular valve seat a, and a valve body to be described later is in the open position through the cavity d. A fluid inlet passage d and a fluid outlet passage d2 communicating with each other are formed in a conventional manner. A valve stem (shaft) 3 extends upward through the valve body 1, and a valve body 2 having an annular valve seat in its lower part is attached to the lower end of the valve stem 3. A handle 19 is attached to the upper end of the handle 19 by means of a nut 20.

As will be explained in detail later, the valve body 2 attached to the lower end of the valve stem 3 can be moved up and down by operating the handle 19.
In FIG. 1, the valve sleeve of the valve body 2 is in a closed position in contact with the valve seat a in the cavity d, and in FIG. 2, the valve body 2 is in the seal replacement position where it has been moved to the uppermost position.

In order to attach the valve body 2 to the lower end of the valve stem 3, an opening 2a with a thread cut on the inner circumference is formed in approximately the upper half of the valve body 2, and a circular opening 2a near the lower end of the valve stem 3 is formed. Columnar small diameter part C
A two-piece holding nut 4 with a thread cut on the outer periphery is fitted into the opening 2 of the valve body 2.
It is designed to be screwed into the inside of a.

A through hole 1a defining a gasket box is formed in the wall of the valve box 1 at a portion of the wall through which the valve stem 3 passes. blank space d
The prize passage hole 1a communicating with the hole 1a has a shelf part 1b in the middle, and a plurality of gland packings 6 made of a material such as graphite are placed on the packing support ring 5 placed on the shelf part 1b. is accommodated. The diameter of the valve body 2 is smaller than the diameter of the through hole 1a.

In order to apply a tightening force to the gland packing 6, a disc spring (elastic member) 9 is disposed above the gland packing through a packing holding bush 7 and a spacer 8, which are packing holding members. 9 is a disc spring support member 10 (
The coned disc spring support member 1 is compressed in the axial direction by the presser bolt 11 (holding member) via the gasket presser member).
0, and is supported between the spacer 8 and the flange portion 10b of the disc spring support member 10.

In the embodiment, three disc springs 9 are used in combination, but the number is not limited to this number.

Moreover, instead of a disc spring, the cylindrical part 1 of the disc spring support member 10
It may be one coil spring that surrounds the cylindrical portion 10a, or it may be a plurality of coil springs that annularly surround the cylindrical portion 10a.

In addition, in order to support the valve stem 3 in a vertically movable manner,
A frame e, usually called a yoke, extends upward from the top of the valve body 1, and a valve stem support member 12 is attached to the upper annular flange e1 of the frame e by a mounting bolt 16 (attachment member).
(shaft support member) is attached. The mounting bolt 16 is
Although only one is shown in the drawing to simplify the drawing, it is preferable to provide an appropriate number of them symmetrically. Further, the number of presser bolts 11 may be plural.

The valve stem 3 has a threaded portion f at and near its upper end, and extends vertically through a bush 12a inserted into the center of the valve stem support member 12. The threaded portion f of the valve stem 3 is threaded into the bush 12a, but not into the disc spring support member 10. Further, the bush 12a is connected to the valve stem support member 1.
It is fixed by screwing into 2.

The above-mentioned presser bolt 11 is screwed into the valve stem support member 12, and its head 11a protrudes from the upper surface of the valve stem support member 12, and its lower end is in contact with the upper surface of the disc spring support member 10. Further, a columnar indicator 15 having a threaded portion at the lower end is provided in a through hole drilled in the axial direction of the valve stem support member 12.
is inserted, and the same threaded portion is screwed and fixed to the disc spring support member 10.

When the assembly is completed as shown in FIG. 1, the gland packing 6 is compressed by further screwing in the presser bolt 11, and the disc spring support member 10 is further lowered.If the screwing is continued, the gland packing 6 is It will be over compressed. The indicator 15 prevents this, and as the disc spring support member 10 lowers, the indicator 15
By moving downward, the position of the top surface of the indicator 15 relative to the top surface of the valve stem support member 12 changes, and the amount of compression of the gland packing 6 can be determined from this change.

In the embodiment, the disc spring support member 10 is held by the presser bolt 11.
is pressed and the lower end of the cylindrical portion 10a comes into contact with the upper surface of the spacer 8 as shown in FIG.
5 and the top surface of the valve stem support member 12 are on the same plane, indicating that the gland packing 6 is properly compressed.

Further, a two-split stopper 13 having a larger diameter than that of the same threaded portion is attached to the lower end of the threaded portion f of the valve stem 3.

This stopper 13 functions to limit further movement of the valve stem 3 by engaging with the bush 12a of the valve stem support member 12 when the valve stem 3 is moved as shown in FIG.

On the other hand, between the upper end of the threaded part f and the handle 19, an appropriate ring-shaped protrusion 17a (which does not need to protrude as long as it has a different color from other parts) is provided at the lower end of the outer peripheral surface. A cylindrical indicator 17 is attached.

Reference numeral 18 designates an indicator plate having a scale portion 18a extending vertically so as to face the indicator 17, and the indicator plate 18 can be appropriately fixed to the valve stem support member 12. When the valve stem 3 moves up and down, the position of the projection 17m of the indicator 17 relative to the scale carved on the scale 18a of the indicator plate 18 changes, and the open/closed state or degree of opening of the valve body 2 can be known.

Next, the operation of the globe valve (2) having the above-mentioned shaft seal structure will be explained. FIG. 1 shows the globe valve V after assembly with the valve body 2 in the fully closed position. In this state, when the handle 19 is rotated in a predetermined direction, the two valve stem support members 12
The valve stem 3, which is screwed into the bush 12m, moves upward while rotating, and the valve body 2 moves from the fully closed position shown in the figure to the fully open position (
(not shown). The movement of the valve body 2 from the fully open position to the fully closed position is performed in substantially the same manner by reversing the procedure. As this operation is repeated, the valve stem 3 is attached to the gland packing 6.
However, since the gland packing 6 is constantly urged downward by the disc spring 9 held in a compressed state, the volume decreases as described above. is compensated for, and the seal tightening force will not be insufficient.

When it is time to replace the gland packing 6, it is necessary to take out the gland packing 6 from the packing box. In that case, by operating the handle described above, move the valve stem 3 upward so that the valve body 2 is in the fully open position, then remove the nut 20 and remove the handle 19.
1 to release the compression force of the disc spring 9, and then tighten the mounting bolt 16.
At this time, the valve stem 3 is held in the upper position because it is screwed into the bush 12m.

Next, as shown in the second Ug, a threaded portion 21 like a long hexagonal bolt is inserted into the tap 6g (threaded hole) formed in the valve stem support member 12 separately from the threaded hole for the mounting bolt 16.
When the jig 21 having the shape a is inserted and screwed so that the lower end of the jig 21 comes into contact with the upper flange e1 of the frame e, the jig 21 and the valve stem support member 12 are in a threaded engagement, so that Using the upper surface of the upper flange e of the frame e as a repulsion seat, the valve stem support member 12 gradually floats upward as shown in FIG. Further, at this time, the valve stem 3 also floats upward together with the valve stem support member 12, and all the parts between the valve body 2 and the valve stem support member 12 move upward. That is, the gland packing 6 placed on the packing support ring 5 of the valve stem 3 also comes out upward. The gland packing 6 thus removed is taken out.

In addition, in the above embodiment, the spacer 8 and the disc spring support member 1
A disc spring 9 is arranged between the
Although the gland packing 6 is pressed by pressing the disc spring support member 10, the disc spring 9 may be provided as necessary and may be omitted together with the columnar indicator 15. In that case, as shown in FIG. Thus, the seal can be deformed so as to directly press the seal bushing 7 with the presser bolt.

In the above case, although not shown, the spacer 8, the disc spring 9, the disc spring support member 10, the presser bolt 11, and the columnar indicator 15 are all omitted, and instead, a well-known clamp mechanism is installed at an appropriate position on the frame e. A holding member (holding member) may be provided, and this may be removably engaged with the packing presser bushing 7, and the gland packing 6 may be held down by the clamp mechanism.

[Effects of the Invention] As described above, according to the present invention, the shaft support member attached to the casing threadably supports the shaft, and the shaft support member receives a jig having a threaded portion. A screw hole is formed through the jig to allow the tip of the jig to come into contact with the casing, so if you want to replace the gland packing, first release the holding member holding the gland packing by the holding member, and then Insert a simple jig such as a hexagonal bolt into the threaded hole of the support member, screw it in until its tip contacts the casing, and then screw it in further to remove the packing support ring and gland packing together with the shaft. Since the gland packing member moves upward and the gland packing is removed from the packing box without being damaged, the removed gland packing can be easily and quickly replaced.

Moreover, since the gland packing is not damaged, no residue remains in the packing box.

In addition, when the gland packing is held down by an elastic member, this elastic member applies a clamping force to the gland packing and prevents the reduction in pressing force resulting from volume reduction due to its use. It is possible to reliably eliminate leakage from the

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing a closed state of a globe valve with a shaft seal structure according to a preferred embodiment of the present invention when assembled, and FIG. 2 is an exploded view of the globe valve of FIG. 1. FIG. 3 is a longitudinal sectional view of a globe valve having a modified embodiment of the shaft seal structure according to the present invention. 1... Casing (valve box) 1a... Packing box (through hole) 3... Shaft (valve stem) 5... Packing support ring 6... Gland packing 7... Packing holding member (packing presser foot) 8
... Packaging pressing member (spacer) 9 ... Elastic member (disc spring) 10 ... Packaging pressing member (disc spring support member 11...
・Holding member (presser/rut) 12... Shaft support member (valve stem support member) 16... Mounting member (mounting bolt) 21... Jig (hex bolt) 21a... Threaded part g...・Screw hole (tapped hole) Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1) A shaft seal structure for sealing between a wall of a casing and a penetrating portion of a shaft passing through the wall, the structure comprising a packing formed on the wall. a box, a packing support ring arranged in the packing box and surrounding the penetration part, a gland packing arranged in the packing box surrounding the penetration part and supported by the packing support ring; A shaft support member that is screwed onto the shaft and attached to the casing for support, a mounting member that attaches the shaft support member to the casing, and a space between the shaft support member and the gland packing that surrounds the shaft. and a holding member that holds the packing presser member in contact with the gland packing, and the shaft support member receives a jig having a threaded portion for fixing the same. A shaft seal structure, wherein a screw hole is formed through the casing to allow the tip of the tool to abut against the wall of the casing. 2) The shaft seal structure according to claim 1, further comprising an elastic member disposed in engagement with the packing pressing member to apply a tightening force to the gland packing.