JPH044365A - Mechanical seal - Google Patents

Abstract

PURPOSE:To enhance sealing performance by providing a shaft packing roughly in a U-shape in cross section having lip sections which come in contact with a rotating shaft and a driven ring with pressure respectively, and hereby providing an elastic body directly acting on the driven ring in order that the driven ring is brought into contact with a seat ring with pressure. CONSTITUTION:A shaft packing 31 in a U-shape in cross section furnished with lip sections 31a and 31b is interposed between the cylindrical section 30a of a driven ring 30 and a rotating shaft 21, and it is composed of a seal member 32 made of synthetic resin, and of a leaf spring 33 located within the seal member, which energizes the lip sections so as to be opened to the inner and the outer circumferential sides, so that a space between the rotating shaft 21 and the driven ring 30, that is, the space between the side X of fluid and the side Y of atmosphere is kept hermetic by means of stable contacting force with pressure. In addition, the driven ring 30 can rotatably slide while exerting bearing force to a seat ring 25 with energizing force directly imparted by an elastic body 28, and the side X of fluid within a stuff box 23 is hermetically sealed from the side Y of atmosphere, so that the side X of fluid and the side Y of atmosphere are rotatably sealed completely while the boundary is formed between the shaft packing 31 and a seal surface A.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a mechanical seal that is a shaft sealing device for a rotating machine.

<Conventional technology> A conventional mechanical seal will be explained with reference to FIG.

A seat ring 5 is firmly supported via an O-ring 4 to a stuffing box 3 provided on a container wall 2 through which a rotating shaft 1 passes.

An end surface (on the left side in the figure) of the seat ring 5 that is substantially perpendicular to the rotating shaft 1 forms a sealed end surface 5a against which a sealed end surface 12c of a driven ring 12, which will be described later, comes into pressure contact.

On the other hand, a stopper 6 is fixed to the rotating shaft 1 by a set screw 7, and locks the base end of the spring 8 and fixes the base end of the first drive pin 9.

Note that the first drive pin 9 is located at the center of the spring 8.

The compression ring 10 has a shape consisting of an enlarged diameter portion 10a on the proximal end side (left side in the figure) and a cylindrical portion 10b on the distal end side, and is slidably mounted on the outer periphery of the rotating shaft 1.

At the base end side of the enlarged diameter portion 10a, the tip of the spring 8 is locked, and a pin hole (not shown) having a diameter slightly larger than the first drive pin 9 is formed. The tip of the guide is inserted so that it can move forward and backward, and is guided by this.

Further, the base end of the second drive pin 11 is fixed to the distal end side of the enlarged diameter portion 10a of the compression ring 10.

The driven ring 12 has a shape consisting of a cylindrical part 12a on the base end side and a reduced diameter part 12b on the distal end side, and is slidably attached to the outer periphery of the rotating shaft 1 similarly to the compression ring 10. The cylindrical portion 12a of the driven ring 12 is arranged to cover the outer circumferential side of the cylindrical portion 10b of the compression ring 10.

A pin hole (not shown) having a diameter slightly larger than that of the second drive pin 11 is formed on the proximal end side of the cylindrical portion 12a of the driven ring 12, into which the tip of the second drive pin 11 is inserted so as to be able to move forward and backward. and is guided by this.

Between the base end side of the reduced diameter portion 12b of the driven ring 12 and the distal end side of the cylindrical portion 10b of the compression ring 10, there is provided a shaft packing 13 having lip portions 13a, 13b and a cross section convex toward the distal end side. It is located.

Here, the contact pressure of the sealed end surface 12c of the driven ring 12 against the sealed end surface 5a of the seat ring 5 (the contact pressure of the sealing surface A) is caused by the compression ring 10 being pressed toward the distal end side by the spring 8 and fluid pressure. The tip of the cylindrical part 10b of 10 is the shaft packing 1
3 by pressing the base end side of the reduced diameter portion 12b of the driven ring 12.

Also, at this time, the cylindrical portion 1 of the compression ring 10
0b tip expands the lips 13a and 13b of the shaft packing 13 toward the rotating shaft 1 side and the driven ring 12 side, and between these, the base end side (fluid side X) and the distal end side (atmospheric side) of the shaft packing 13 Side Y) is sealed air-tight (liquid-tight).

Further, the rotational force of the rotating shaft 1 is transmitted from the stopper 6 to the compression ring 10 via the first drive pin 9, and further transmitted to the driven ring 12 via the second drive pin 11.

As explained above, the driven ring 12 is indirectly pressed against the seat ring 5 by the spring 8 via the compression ring 10 and the shaft packing 13, and is rotated and slid while generating a contact pressure to seal the shaft. I am supposed to do it.

As a result, the fluid side X and the atmosphere side Y are completely sealed between the shaft packing 13 and the sealing surface A.

<Problems to be Solved by the Invention> However, in the above-mentioned mechanical seal, if the fluid to be sealed is in the form of a slurry or a substance with adhesive or polymerizable properties, the
As shown in the figure, lip portions 13a, 1 of the shaft packing 13
The fluid hardens and accumulates near 3b, forming deposit H.
There was a problem in that the lip portions 13a and 13b bit the deposits H and the sealing performance was impaired.

In addition, the deposits H fix the lips 13a and 13b, preventing them from expanding, which not only impairs the sealing performance of the shaft seal 13 but also prevents the shaft seal 13 from moving in the axial direction. is suppressed, so driven ring 1
There was also a problem in that the urging force in the axial direction of the seat ring 2 was impaired, the contact pressure against the seat ring 5 was reduced, and the sealing performance at the sealing surface A was also impaired.

Furthermore, as shown in FIG. 9, even if the lip portion 13a (or 13b) of the shaft packing 13 creeps into the gap between the inner and outer circumferential sides of the compression ring 10 during use and gets caught, a similar problem may occur. A problem arises.

Furthermore, as shown in FIG. 10, when an O-ring type shaft packing 13' is used, the same problem occurs because smooth movement is obstructed by deposits.

In view of the above problems, the present invention aims to provide a mechanical seal with good sealing performance.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a seat ring fixed to a stuffing box, which is attached to the outer periphery of a rotating shaft, rotates integrally with the seat ring, and is slidable in the axial direction. A mechanical seal that seals a shaft by pressing a driven ring has the following configuration.

(1) Distortion between the rotating shaft and the driven ring: A shaft packing is provided that has a lip that presses against it and has an approximately U-shaped (including V-shaped) cross-sectional shape, and is driven by the seat ring. In order to press the ring, an elastic body is provided that acts directly on the driven ring.

(2) Assuming that the driven ring has a reduced diameter part near the seat ring, between the rotating shaft and the driven ring and on the side opposite to the seat ring of the reduced diameter part of the driven ring, A shaft packing having opposing lip portions is provided, and a main elastic body that acts directly on the driven ring is provided in order to press the seat ring against the driven ring, and
An auxiliary elastic body is provided which acts on the shaft packing and presses the driven ring against the seat ring via the shaft packing, and expands and presses the lip portion of the shaft packing toward the rotating shaft side and the driven ring side.

<Operation> According to the configuration (1) above, the lip portion of the shaft packing comes into pressure contact with the rotating shaft and the driven ring, and the driven ring, on which the elastic body acts directly, comes into pressure contact with the seat ring, without using a compression ring.

Therefore, the shaft packing and the driven ring exhibit a sealing effect without influencing each other.

According to the configuration (2) above, as in the past, the lip of the shaft packing is brought into pressure contact with the rotating shaft and the driven ring by the auxiliary elastic body via the compression ring, the main elastic body acts directly, and the auxiliary elastic body presses against the rotating shaft and the driven ring. The elastic body acts on the shaft packing, and the driven ring is pressed against the seat ring via the elastic body.

Therefore, since the driven ring mainly obtains the biasing force against the seat ring by the main elastic body, the shaft packing and the driven ring can perform the sealing action with almost no influence on each other, as described above. Demonstrate.

<Examples> Examples according to the present invention will be described below based on FIGS. 1 to 6, but the present invention is not limited to the following examples unless it exceeds the gist thereof. .

First, a first embodiment will be described with reference to FIG.

A seat ring 25 is firmly supported via an O-ring 24 to a stuffing box 23 provided on a container wall 22 through which a rotating shaft 21 passes.

The end surface (left side in the figure) of the seat ring 25 that is substantially perpendicular to the rotating shaft 21 is a sealed end surface 30c of a driven ring 30, which will be described later.
forms a sealed end surface 25a that is pressed into contact.

On the other hand, a stopper 26 is attached to a set screw 27 on the rotating shaft 21.
The base end of an elastic body 28 made of a spring, bellows, etc. is locked, and the base end of a drive pin 29 is fixed.

The driven ring 30 has a shape consisting of a cylindrical portion 30a on the base end side and a reduced diameter portion 30b on the distal end side, and is slidably mounted on the outer periphery of the rotating shaft 21. A stepped portion 30d for preventing the shaft packing 31 from being removed, which will be described later, is formed on the inner peripheral side of the base end of the cylindrical portion 30a.

At the proximal end of the cylindrical portion 30a, the tip of the elastic body 28 is locked, and a pin hole 30e having a slightly larger diameter than the drive pin 29 is formed, into which the tip of the drive pin 29 is inserted so as to be able to move forward and backward. ing.

A shaft packing 31 is fitted between the cylindrical portion 30a of the driven ring 30 and the rotating shaft 21.

This shaft packing 31 has a substantially U-shaped cross-section and has lip portions 31a and 31b, and a sealing member 32 made of synthetic resin such as polytetrafluoroethylene (PTFE) and the lip portion on the inside thereof. It consists of an elastic member 33 made of a plate spring that is biased to expand toward the inner and outer circumferential sides.

Then, between the rotating shaft 21 and the driven ring 30, the base end side (fluid side ) is sealed.

Here, the contact pressure of the sealed end surface 30c of the driven ring 30 against the sealed end surface 25a of the seat ring 25 (the contact pressure of the seal surface A) can be directly applied by the elastic body 28, and in the state where the contact pressure is obtained. , can rotate and slide.

Moreover, the rotational force can be obtained from the rotation shaft 21 via the stopper 26 and the drive bin 29.

As described above, the shaft packing 31 can airtightly partition the fluid side X in the stuffing box 23 from the atmosphere side Y between the rotating shaft 21 and the driven ring 30.

Further, the driven ring 30 obtains a direct biasing force from the elastic body 28 and can rotate and slide while maintaining the contact pressure on the seat ring 25, so that the fluid side X in the stuffing bollus 23 is separated from the atmospheric side Y. , can be hermetically sealed and partitioned.

As a result, the fluid side X and the atmosphere side Y are completely sealed between the shaft packing 31 and the sealing surface A.

Also, since there is no compression ring, the rotating shaft 21
The gap between the driven ring 30 and the driven ring 30 is widened, making it difficult for the fluid to harden and accumulate, and also preventing the lip from getting caught.

Therefore, malfunction of the driven ring 30 will not occur.

Furthermore, even if the fluid hardens and accumulates near the lips 31a and 3Ib of the shaft packing 31, the shaft packing 31 is not biased in the axial direction, so the lips 31a and 31b can overcome the deposits, preventing leakage. There is no fear that this will occur, and the operation of the driven ring 30 will not be affected in any way.

In addition, various other types of shaft packing 31 can be used, such as those made of a material that itself has both sealing properties and elasticity, such as rubber, As shown in (a) a perspective view and (b) a cross-sectional view, inside the sealing member 32, which is made of synthetic resin such as PTFE and has a substantially U-shaped cross-sectional shape, a
A combination of elastic members 33 made of letter-shaped leaf springs, a modified version of the elastic member 33 as shown in FIG.
a) Perspective view.

As shown in the sectional view (b), the elastic member 33 is a coiled spring, and as shown in FIG. 5, the elastic member 33 is an O-ring made of rubber or the like.

The above-mentioned "U-shaped" seal member does not necessarily mean U-shaped.
The shape is not limited to the shape of a letter, and may include variations such as a U-shape, a ■-shape, and a semicircle.

Next, a second embodiment will be described with reference to FIG.

The same parts as in the first embodiment are given the same reference numerals.
The explanation will be omitted.

The base end of the main elastic body 41 is locked to the stopper 26 from the outside, and the base end of the auxiliary elastic body 42 is locked to the stopper 26 from the inside. Furthermore, in the vicinity of the auxiliary elastic body 42, a first
The base end of the drive pin 43 is fixed.

The compression ring 44 has almost the same shape as the conventional example, and has a shape consisting of an enlarged diameter portion 44a on the proximal end side and a cylindrical portion 44b on the distal end side, and can freely slide around the outer periphery of the rotating shaft 21. is installed on.

The distal end side of the auxiliary elastic body 42 is locked on the proximal end side of the enlarged diameter portion 44a, and a pin hole (not shown) having a diameter slightly larger than the first drive pin 43 is formed. The tip of the pin 43 is fitted so that it can move forward and backward.

Further, a second drive pin 4 is provided on the distal end side of the enlarged diameter portion 44a.
The proximal end of 5 is fixed.

The driven ring 46 has a shape consisting of a cylindrical portion 46a on the proximal end side and a reduced diameter portion 46b on the distal end side, and is slidably mounted on the outer periphery of the rotating shaft 21.

At the proximal end side of the cylindrical portion 46a, the distal end side of the main elastic body 41 is locked, and a pin hole (not shown) having a diameter slightly larger than the second drive pin 45 is formed. The tip of the pin 45 is fitted so that it can move forward and backward.

Between the proximal end of the reduced diameter portion 46b of the driven ring 46 and the distal end of the cylindrical portion 44b of the compression ring 44, there is provided a shaft packing 47 having lip portions 47a, 47b and a convex cross-sectional shape toward the distal end. It is located.

Here, the contact pressure of the driven ring 46 to the seat ring 25 can be applied directly from the main elastic body 41, and additionally via the compression ring 44 and the shaft packing 47. It can also be obtained indirectly from the elastic body 42.

Further, the rotational force is applied from the rotating shaft 21 to the stopper 26° first
Drive pin 43. Compression ring 44° 2nd
It can be obtained via the drive pin 45.

As explained above, according to this embodiment, the shaft packing 4
7 obtains a biasing force from the auxiliary elastic body 42 via the compression ring 44, and a lip portion 47a.

47b is expanded, and the fluid side X in the stuffing box 23 can be sealed and partitioned from the atmospheric side Y between the driven ring 46 and the rotating shaft 21.

In addition, the driven ring 46 can obtain the biasing force to the seat ring 25 directly from the main elastic body 41, so regardless of the state of the shaft packing 47, the contact pressure is always stable. Can be rotated, slid and sealed.

As a result, the fluid side X and the atmosphere side Y are completely sealed between the shaft packing 47 and the sealing surface A.

<Effects of the Invention> As explained above, according to the present invention, the shaft packing and the driven ring can each perform their sealing functions almost independently, so even if a problem occurs with either of them, there is no problem. , each sealing function can be exerted without being affected by it.

As a result, the operational state of the driven ring is no longer influenced by the state of the shaft packing, as in the past, and a mechanical seal with excellent shaft sealing performance can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a mechanical seal showing a first embodiment of the present invention, FIGS. 2(a), (b), 3, and 4 (
a), (b), and FIG. 5 are partial perspective views and sectional views showing an example of the shaft packing, and FIG. 6 is a partial perspective view and a sectional view showing a second embodiment.
FIG. 7 is a sectional view of a main part of a conventional mechanical seal, and FIGS. 8 to 10 are sectional views of main parts showing problems with the conventional mechanical seal. 21... Rotating shaft 22... Container wall 23...
Stuffing box 25... Seat ring
26... Stopper 28... Elastic body 30.
... Driven ring 31 ... Shaft packing 31a,
30b...Lip portion 41...Main elastic body 42
... Auxiliary elastic body 44 ... Compression ring 46 ... Driven ring 47 ... Shaft packing 47a, 47b ... Lip part

Claims (2)

[Claims] (1) A mechanical seal that performs shaft sealing by press-contacting a driven ring that is attached to the outer periphery of the rotating shaft and that rotates integrally and is slidable in the axial direction to a seat ring that is firmly supported on a stuffing box. and the driven ring, a shaft packing having a lip portion that presses against each other and having a substantially U-shaped cross section is provided, and a shaft packing that acts directly on the driven ring in order to press the driven ring against the seat ring. A mechanical seal characterized by having an elastic body. (2) A driven ring, which is attached to the outer periphery of the rotating shaft and rotates integrally with it, is slidable in the axial direction, and has a reduced diameter portion near the seat ring is pressed into contact with the seat ring fixed to the stuffing box. In a mechanical seal for sealing, a shaft packing having a lip portion facing the rotating shaft and the driven ring, respectively, between the rotating shaft and the driven ring and on a side opposite to the seat ring of a reduced diameter portion of the driven ring. In order to press the driven ring against the seat ring, a main elastic body is provided that acts directly on the driven ring, and acts on the shaft packing to press the driven ring against the seat ring. A mechanical seal characterized in that an auxiliary elastic body is provided that expands and presses the lip portion of the shaft packing toward the rotating shaft side and the driven ring side.