JPH0536145Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a bellows seal consisting of a rotating side assembly of unit structure held on a rotating shaft and a stationary sealing ring held on a casing. This invention relates to an outward flow mechanical seal using a fluororesin bellows as a secondary seal in an assembly.

[Conventional technology]

In general, a conventional bellows seal consists of a stationary sealing ring 1' held on a casing 2' and a rotating side assembly 3' of unit structure held on a rotating shaft 4', as shown in FIG. The assembly 3' includes a rotary seal ring 5', a retaining ring 7' that engages and holds the rotary seal ring 5' in a non-rotatable manner, and a front end portion 8'a that is fitted into the stationary seal ring 5' and the retaining ring 7'. A bellows 8' made of fluororesin that is in close contact with each other, a split annular bellows fixing ring 10' that tightly fixes the rear end 8'b of the bellows 8' to the rotating shaft 4', a retaining ring 7', and a bellows fixing ring. 10' and an interposed spring 9'.

[The problem that the idea aims to solve]

However, in the case of such a bellows seal, the spring 9' is placed between the retaining ring 7' that fixes the front end 8'a of the bellows 8' and the bellows fixing ring 10' that engages the rear end 8'b. Because it is inserted in
When the rotating side assembly 3' is not assembled on the rotating shaft 4' and is stored, the tension of the spring 9' always acts on the bellows 8' and therefore on the bellows-like elastic part 8'c, as shown in FIG. This expansion/contraction portion 8'c may expand non-uniformly and stress concentration may occur in a portion of the bellows 8', resulting in a very poor storage condition of the bellows 8'.

Furthermore, when the rotating assembly 3' is assembled into the rotating shaft 4', since the inner diameter of the bellows 8' is narrowed due to expansion, it is difficult to insert the bellows 8' into the rotating shaft 4' properly. In particular, this seal is often used to seal against corrosive fluids such as sulfuric acid, and the surface of the rotating shaft 4' is generally lined with ceramic, glass, etc. It is becoming more difficult to insert and incorporate.

In addition, the bellows 8' is tightly fixed to the rotating shaft 4' only by the tightening force of the bellows fixing ring 10', the bellows 8' is made of fluororesin with a low coefficient of friction, and the external In directional flow mechanical seals, fluid pressure is applied to the divided bellows fixed ring 1.
0', the holding force of the bellows 8' to the rotating shaft 4' is small, and therefore the sealing pressure is low. As mentioned above, this becomes more noticeable because the surface of the rotating shaft 4' is lined with a low-friction material such as ceramic or glass. As shown in FIG. 4, a stopper 16 for holding the bellows is fixed to the rotating shaft 4' to increase the holding force of the bellows 8'. Providing this prevents the unitization of the rotating assembly 3' and makes its assembly and storage difficult.

An object of the present invention is to provide a bellows seal that allows the rotating assembly to be stored as a unit with the bellows held at a free length and that can be easily assembled into the rotating shaft.

Another object of the present invention is to provide a bellows seal that can increase the bellows retaining force and significantly improve the seal pressure resistance.

[Means to solve the problem]

The bellows seal of the present invention which has solved this problem is particularly a bellows seal consisting of a stationary seal ring held in a casing and a rotating assembly of a unit structure held on a rotating shaft, the rotating assembly comprising a rotating seal ring capable of sliding against the stationary seal ring, an assembly fixed ring fixed to the rotating shaft, a retaining ring which engages and holds the rotating seal ring so that it cannot rotate relative to the stationary seal ring, a bellows made of fluorine resin interposed between the rotating seal ring and the assembly fixed ring, the front end of which is fitted and closely attached to the rotating seal ring and the retaining ring,
The assembly fixing ring is connected to the assembly fixing ring via a connecting bolt extending in the axial direction, and engages and holds the retaining ring so that it cannot rotate relative to the retaining ring but can move relative to the axial direction, and fastens and fixes the rear end of the bellows to the rotating shaft, and a spring is inserted between the assembly fixing ring and the retaining ring to press the rotating seal ring against the stationary seal ring, and the assembly fixing ring is configured so that it can be temporarily fixed to the bellows fixing ring by the connecting bolt while the bellows and the spring are held at their free lengths.
The rotating shaft in this invention is a general term for the rotating shaft and the sleeve fitted onto it.

In such a bellows seal, the bellows fixing ring includes an annular main body connected to the assembly fixing ring via a connecting bolt, and is fitted internally into the main body and externally engaged with the rear end of the bellows. It consists of a split annular tightening body having a tapered outer peripheral surface whose diameter gradually expands in the direction of the assembly fixed ring, and the diameter of the tightening body is reduced by tightening the main body in the direction of the assembly fixed ring with a connecting bolt. It is preferable to leave it configured.

[Effect]

When the rotating assembly is not installed on the rotating shaft, each component of the rotating assembly can be interconnected by temporarily fixing the assembly fixing ring to the bellows fixing ring that engages the rear end of the bellows. The rotating assembly can be stored as a unit.

In such storage conditions, the retaining ring connects the bellows, but since the assembly fixing ring is an independent member from the bellows, the tension of the spring inserted between the retainer and the assembly fixing ring is , does not act directly on the bellows. Furthermore, by temporarily fixing the assembly fixing ring to the bellows fixing ring, there is a risk that the tension of the spring will indirectly act on the bellows fixing ring and therefore the bellows with which it engages. This problem can be reliably avoided by keeping the distance between the temporary fixing rings at a certain distance or more. That is, the temporary spacing between both fixed rings is set such that when the bellows fixed ring is brought to a position where the bellows is held at its free length, the assembly fixed ring is separated from the retaining ring by a distance equal to or more than the free length of the spring. If this is set, the rotating assembly can be made into a unit with the bellows and spring held at their free lengths.

Therefore, the rotating assembly can be stored with the bellows not extended. As a result, the bellows does not suffer from deformation or stress concentration during storage.
It can also be easily inserted and assembled into the rotating shaft.

After the rotating side assembly is inserted into the rotating shaft, the assembly fixing ring is fixed to the rotating shaft, and the connecting bolt is tightened to integrally connect the bellows fixing ring and the assembly fixing ring, and the bellows is attached to the rotating shaft by the bellows fixing ring. It is assembled into the rotating shaft by tightening and fixing.

When the bellows fixing ring is composed of an annular main body and a split annular tightening body as described above, when the main body is tightened with a connecting bolt toward the assembly fixing ring, the diameter of the tightening body is reduced and the bellows rotates. Tightly fixed to the shaft. The bellows is tightened and fixed by the non-divided main body through the tightening body, and the assembly fixing ring is integrally connected to the bellows fixing ring, and its holding force to the rotating shaft also acts as part of the bellows holding force. Therefore, the bellows retention force is significantly increased compared to conventional seals, and the seal pressure resistance is improved. By the way, the assembly fixing ring is the same as the stopper 16 in the conventional seal.
Similarly, the bellows retaining force is increased, but unlike the stopper 16, as described above, it does not hinder the unitization of the rotating assembly.

[Example] Hereinafter, the structure of the present invention will be specifically explained based on the example shown in FIGS. 1 to 3.

In the bellows seal shown in FIG. 1, 1 is a stationary sealing ring fixedly held on a casing 2, 3 is a rotating assembly of unit structure held on a rotating shaft 4, and a rotating sealing ring 5 and a fixed assembly ring 6 are connected to each other. It includes a retaining ring 7, a bellows 8, a plurality of springs 9... and a bellows fixing ring 10.

The rotary sealing ring 5 has a concave groove 5 formed on its outer peripheral surface.
By engaging the protrusion 7a formed at the front end of the retaining ring 7 with the retaining ring 7, the retaining ring 7 is engaged and held so as to be non-rotatable and movable in the axial direction.

As shown in FIGS. 1 and 3, the assembly fixing ring 6 is divided into two parts in the radial direction, and is tightly fixed to the rotating shaft 4 with tightening bolts 11, 11.

The bellows 8, as shown in FIGS. 1 and 3,
Annular front and rear ends 8a, 8b and bellows-shaped extensible part 8c
It is made of fluororesin and is expandable and contractible in the axial direction, and the front end 8a is tightly fitted to the rear end of the rotary sealing ring 5 and the front end of the retaining ring 7 via the pressing ring 12. The end portion 8b is tightly fixed to the rotary shaft 4 by a bellows fixing ring 10, thereby providing a secondary seal between the rotary sealing ring 5 and the rotary shaft 4 while allowing the rotary seal ring 5 to move in the axial direction.

The springs 9 are interposed between the assembly fixed ring 6 and the retaining ring 7, and press the rotating sealing ring 5 against the stationary sealing ring 1. Spring 9...
are held at one end in a holding hole 7b formed at the rear end of the holding ring 7, and are arranged around the rotating shaft 4 at regular intervals.

As shown in FIGS. 1 and 3, the bellows fixing ring 10 includes an annular main body 13 and a split annular tightening body 14.
It consists of.

This main body 13 is connected to the assembly fixing ring 6 by a plurality of connecting bolts 15 extending in the axial direction. A plurality of drive pins 13a are protruded from the front end of the main body 13, and by engaging each drive pin 13a into each engagement hole 7c formed at the rear end of the retaining ring 7, the retaining ring 7 are engaged and connected so that they cannot rotate relative to each other and can move in the axial direction. Further, the main body 13 is formed with insertion holes 13b through which the springs 9 are inserted, so that the tension of the springs 9 does not directly apply to the bellows fixing ring 10. In addition, when the spring groups 9 are arranged in an annular region having a larger diameter than the outer diameter of the bellows fixed ring 10, that is, the main body 13,
It is not necessary to provide such insertion holes 13b. Further, a diameter reducing portion 13c is formed in the inner circumferential portion of the main body 13, and the diameter is gradually enlarged toward the rear.

On the other hand, the tightening body 14 has a divided structure in which the outer circumferential surface is formed into a tapered surface 14a whose diameter gradually expands rearward, and the inner circumferential portion thereof has an engagement member that externally engages with the rear end portion 8b of the bellows 8. A stepped portion 14b is formed.
This tightening body 14 is operated by moving the main body 13 backward, that is, in the direction of the assembly fixing ring 6, with its rear end in contact with the assembly fixing ring 6.
By moving the contact position of the diameter reduction action portion 13c with respect to the tapered surface 14a rearward, the diameter is gradually reduced and the rear end portion 8b of the bellows 8 is tightened and fixed to the rotating shaft 4. In this example,
The slope θ of the tapered surface 14a is set to about 10°. Generally, this slope θ is appropriately set in the range of 5°≦θ≦45° (more preferably 5°≦θ≦20°) according to various conditions such as the friction coefficient μ of the bellows 8.

When the rotating assembly 3 is not assembled into the rotating shaft 4, it is maintained in a unitized state as shown in FIG.

That is, the assembly fixing ring 6 is temporarily fixed to the main body 13 of the bellows fixing ring 10 by connecting bolts 15 . The spacing between the fixed rings 6 and 10 due to this temporary fixing is such that when the bellows fixed ring 10 is brought to a position where the bellows 8 is held at a free length, the assembly fixed ring 6 is moved from the retaining ring 7 to the spring 9.
They are set so that they are separated by a distance equal to or more than the free length of. Therefore, the rotating assembly 3 includes the bellows 8 and the spring 9...
It is stored as a unit with the length maintained at its free length. Therefore, problems such as stress concentration on the bellows 8 do not occur during storage.

Further, the rotation side assembly 3 is assembled into the rotation shaft 4 in the following manner.

First, the rotating assembly 3 is inserted into the rotating shaft 4. At this time, the bellows 8 is maintained at a free length and is not deformed non-uniformly due to narrowing of the inner diameter, so that it can be easily inserted into the rotating shaft 4.

Then, the assembly fixing ring 6 is tightly fixed to the rotating shaft 4 by tightening the tightening bolts 11, 11, and then the bellows 8 is tightly held to the rotating shaft 4.
That is, the connecting bolts 15 are tightened to draw the main body 13 of the bellows fixing ring 10 toward the assembly fixing ring 6, thereby reducing the diameter of the tightening body 14 and tightening and fixing the rear end portion 8b of the bellows 8 to the rotating shaft 4. be.

In this way, the bellows 8 is tightened and fixed by the non-divided main body 13 via the tightening body 14, and the assembly fixing ring 6 is integrally connected to the bellows fixing ring 10, and the rotation axis 4 is Since the retaining force also acts as a part of the bellows retaining force, the retaining force of the bellows 8 is greatly increased compared to conventional seals, and the seal pressure resistance is improved.

[Effect of idea]

In the bellows seal of claim 1, since the rotating assembly can be stored as a unit in which the bellows and spring are held at free lengths, the bellows does not have uneven tension due to the tension of the spring during storage. It does not cause any inconveniences such as deformation or stress concentration, ensuring good storage conditions, and easy insertion into the rotating shaft.
It can also be easily integrated.

Furthermore, in the bellows seal of claim 2,
It is possible to increase the holding force of the bellows to the rotating shaft, and it is possible to significantly improve the sealing pressure resistance.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view showing an embodiment of the bellows seal according to the present invention, Fig. 2 is a longitudinal side view showing the storage state of the rotating side assembly, and Fig. 3 is an exploded perspective view of the rotating side assembly. Yes, 4th
The figure is a half-cut vertical side view showing a conventional bellows seal, and FIG. 5 is a half-cut vertical side view showing the storage state of the rotating assembly. 1... Stationary sealing ring, 2... Casing, 3...
Rotating side assembly, 4... Rotating shaft, 5... Rotating sealing ring, 6... Assembly fixing ring, 7... Retaining ring, 8... Bellows, 8a... Front end of bellows, 8b... Rear end of bellows Part, 9... Spring, 10... Bellows fixed ring, 13... Main body, 1
4...Tightening body, 14a...Tapered surface, 15...Connecting bolt.

Claims (1)

[Claims for Utility Model Registration] (1) A bellows seal consisting of a stationary sealing ring held in a casing and a rotating side assembly having a unit structure held on a rotating shaft, wherein the rotating side assembly is connected to the stationary sealing ring. A rotary sealing ring that can be slidably contacted, an assembly fixed ring fixed to the rotating shaft, a retaining ring that engages and holds the rotary sealing ring in a manner that prevents relative rotation, and is inserted between the rotary sealing ring and the assembly fixed ring. A bellows made of fluororesin whose front end is tightly fitted to the rotary sealing ring and the retaining ring is connected to the assembly fixed ring via a connecting bolt extending in the axial direction, so that the retaining ring cannot be rotated relative to the A bellows fixing ring that engages and holds the bellows relatively movably in the axial direction and tightly fixes the rear end of the bellows to the rotating shaft, and a stationary sealing ring that is inserted between the assembly fixing ring and the retaining ring, and a spring for pressing the bellows, and the bellows is configured such that the assembly fixing ring can be temporarily fixed to the bellows fixing ring with a connecting bolt while the bellows and the spring are held at a free length. sticker. (2) The bellows fixing ring includes an annular body connected to the assembly fixing ring via a connecting bolt, and a bellows fixing ring that is fitted inside the main body and externally engaged with the rear end of the bellows. Consisting of a split annular tightening body having a tapered outer circumferential surface that gradually expands in diameter, the tightening body is configured so that the diameter of the tightening body can be reduced by tightening the main body in the direction of the assembly fixing ring with a connecting bolt. The bellows seal according to claim 1, characterized in that: