JPH0129332Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to back-up springs for mechanical seals, and is particularly aimed at improving the thermal expansion resistance and low-friction characteristics of back-up springs in mechanical seals used under high pressure and high temperatures. This is related.

[Conventional technology]

FIG. 3 shows a schematic configuration of a conventional high-pressure, high-temperature mechanical seal device of this type. This third
In the figure, a mechanical seal device for high pressure and high temperature has a seal housing 1 provided with a seal flange 2, and a rotating shaft 3 rotatably mounted in the seal housing 1.
A stationary seal ring 4 fixed to the side, a rotating seal ring 5 that obtains a sealing effect by bringing a rotating seal surface 5a into contact with the stationary seal surface 4a of the stationary seal ring 4, and a rotating seal ring 5 that obtains a sealing action by bringing the rotating seal surface 5a into contact with the stationary seal surface 4a of the stationary seal ring 4. It has a rotation operating ring 6 that is held on the side and connected and fixed to the rotating shaft 3 side.

That is, the stationary seal ring 4 is attached to the seal flange 2 while being sealed by an O-ring 7 and prevented from rotating by a locking bolt 8, and the rotating ring 6 has a predetermined inner diameter. The rotating shaft 3 is fitted into the rotating shaft 3 through a back-up spring 10 on the inner end surface side of the ring 6 and an O-ring 11 in contact with the back-up spring 10 in the space 9 . From the other end side of the rotary actuating ring 6, the press ring 12, which is slidable only in the axial direction, is in contact with the guide pin 13 and the guide hole 14, and the spring 16 is held by a spring retainer 15 fixed to the rotary shaft 3. Therefore, the back-up spring 10 and the O-ring 11 are pressed through this pressing ring 12.

In the configuration of this conventional device, the interior of the stationary seal ring 4 is defined by the rotating pressure sealing surface formed by the seal surfaces 4a and 5a and the stationary pressure sealing surface of the O-ring 11 relative to the rotating shaft 3, respectively. The circumferential side is atmospheric pressure or low pressure side A,
The outer circumferential side of the rotary seal ring 5 and the pressure side of the press ring 12 that comes into contact with the O-ring 11 are set as the high-pressure side B of the in-machine fluid, so that a sealing effect can be obtained on each side.

[Problem that the invention attempts to solve]

However, in the case of the conventional configuration, the material of the back-up spring 10 interposed between the inner end surface of the rotary actuating ring 6 and the O-ring 11 is usually one that has excellent thermal expansion resistance and a low coefficient of friction. PTFE
Heat-resistant resins such as (polytetrafluoroethylene) and TFE (tetrafluoroethylene) are used.

However, these heat-resistant resins such as PTFE and TFE have a larger coefficient of linear expansion than metal materials such as shafts and rings to which they are applied.
For example, about 10 to 15 × 10 ^-6 /℃ for metal materials
When the shaft diameter is 100mm and the temperature is 100℃,
It is known that the diameter increases by 1.5 mm.
Therefore, the high-temperature back-up spring 10, which is provided to minimize the gap with the rotating shaft 3 and prevent the O-ring 11 from protruding, is designed to prevent linear expansion between the rotating shaft 3 and the rotating shaft 3 in the same part. It is necessary to use metal parts with similar coefficients, and in this case, the rotating shaft 3 and back-up spring 1
The gap with 0 cannot be made too small. In other words, the part where this back-up spring 10 is inserted is constantly moving slightly to ensure the sealing effect by following the radial movement on the sealing surface, and if the gap in this part is minute, the outer circumferential surface of the rotating shaft This may cause galling between the ring and the inner circumferential surface of the ring, or catch may occur due to partial contact, impairing the follow-up ability, and the resistance on the inner circumferential surface of the ring Not only this, but also a large resistance will be generated at the end face of the ring. As shown in FIG. 4, the back-up spring 10 is pressed against the axially inner end surface of the rotary actuating ring 6 by the thrust generated by the hydraulic pressure P on the high-pressure side B via the O-ring 11. Moreover, as a matter of course, the greater the hydraulic pressure P, the greater the coefficient of friction at the contact surface of this thrust force, and the back-up spring 10 itself acts as if it were integrated with the rotary actuating ring 6. Therefore, if the ability to follow the radial movement of the back up spring 10 is impaired in this way, the reason for its existence will be lost, so it is necessary to reduce the contact resistance of the back up spring 10 itself. are extremely important, and making the backup spring 10 made of metal is itself disadvantageous in achieving each of these points.

[Means for solving problems]

This idea was made to improve these conventional problems, and the back-up spring itself was made of a metal with approximately the same coefficient of linear expansion as the rotating shaft to which it was applied, and A resin layer such as PTFE or TFE, which has excellent thermal expansion resistance and low friction properties, is formed on at least the pressure-receiving surfaces of both end faces of the manufactured backup spring, or a ring-shaped resin plate is provided. .

That is, this invention brings the seal surfaces of both the stationary and rotating seal rings into contact with each other to form a rotating pressure seal surface, and also connects the rotating seal ring, or the rotating actuating ring that holds the rotating seal ring, and the rotating shaft. A back-up spring member and an O-ring are successively interposed on the inner end surface of the ring to form a stationary pressure sealing surface, with the inner circumference of the stationary seal ring being the low pressure side and the outer circumference of the rotating seal ring being the low pressure side. In the mechanical seal with the side facing the high pressure side, the back-up spring member is made of a metal having approximately the same coefficient of linear expansion as the rotating shaft, and both pressure-receiving end surfaces of the metal back-up spring are made of PTFE, This mechanical seal back-up spring device is characterized by forming a resin layer such as TFE with excellent thermal expansion resistance and low friction properties, or by disposing a ring-shaped resin plate.

〔Example〕

Hereinafter, embodiments of the backup springing device according to this invention will be described in detail with reference to FIG. 1 and FIGS. 2a and 2b.

These FIG. 1 and FIGS. 2a and 2b each show an outline of the device configuration according to the first and second embodiments, and in each figure, the above-mentioned FIGS.
The same reference numerals as in the conventional device in the figure indicate the same or corresponding parts.

First, in the first embodiment shown in FIG. 1, as a backup spring member 2 corresponding to the backup spring 10 in the conventional device, the entire circumferential surface of a metal backup spring 22 has thermal expansion resistance, A resin layer 23 made of PTFE, TFE, etc., which has excellent low friction properties, is adhered and formed by coating.The coating thickness of the resin layer 23 varies depending on the sealing conditions of the part to be used, but it is 20~
It is sufficient if the coating thickness is about 100 μm, and in this case, if the coating thickness is too thick, especially at the portion in contact with the rotating shaft 3, that is, the inner circumferential surface, there is a risk that the same problems as those caused by using the same resin alone as mentioned earlier may occur. Therefore, it is desirable to pay sufficient attention to its thickness.

Further, in the second embodiment device shown in FIG. 2a, similarly, as the back-up spring member 21, a metal back-up spring 22, and a thermal expansion resistant material disposed on both end surfaces of the metal back-up spring 22,
A ring-shaped resin plate 24 made of PTFE, TFE, etc. with excellent low friction properties is provided, and the ring-shaped resin plate 24 has an inner diameter that creates a predetermined gap 25 between it and the rotating shaft 3. It should be able to absorb thermal expansion under high-temperature usage conditions, and its axial thickness may vary depending on the sealing conditions of the part to be used, but may be about 1 to 1.5 mm.

In the case of this second embodiment device, the second b.
As shown in the figure, it is effective to cut out a part of the ring-shaped resin plate 24 at a predetermined gap 26 to absorb thermal expansion under high-temperature usage conditions. .

Therefore, when using the device configuration of each of these embodiments, a metal backup spring 22 and a coating resin layer 23 of PTFE, TFE, etc. on its entire circumference, or a ring of PTFE, TFE, etc. on both end surfaces thereof. By using the shaped resin plate 24 in combination, the frictional resistance of the radial movement to ensure the sealing effect is determined by the difference in the coefficient of friction between metal and PTFE, which is approximately 0.3 and 0.06, respectively. can be reduced to about 1/5, which is equal to
For this reason, for example, when the sealing conditions are sealing oil at a pressure of 80 kg/cm ² and a temperature of 250°C, the conventional device could not seal due to poor followability, but this example device can seal without leakage. could function.

In the device of the above embodiment, the rotary actuating ring 6 that holds the rotary seal ring 5 and the rotary shaft 3
In the configuration of the O-ring 11 that is interposed between the
Although the description has been made regarding the back-up spring member 21 for receiving pressure on the ring 11, it goes without saying that this invention can also be similarly applied to the case where the back-up spring member 21 is directly interposed between the rotary seal ring 5 and the rotary shaft 3. be.

[Effect of idea]

As described in detail above, according to this invention, in a pressure-receiving back-up spring member for an O-ring that forms a stationary pressure-contact sealing surface, this back-up spring member can be attached to a rotating shaft or the like with a coefficient of linear expansion that is approximately In addition to being made of equal metal, both pressure-receiving end surfaces of this metal back-up spring are made of PTFE, TFE, etc.
Since a resin layer such as , or a ring-shaped resin plate is provided, both of these, that is, metal and
The advantages and disadvantages of resins such as PTFE and TFE can be mutually compensated for, making it possible to sufficiently reduce frictional resistance and dramatically improve lubricity, especially when used under high temperature and high pressure conditions. In addition to being able to improve the performance of the device, it also has a simple configuration and can be provided easily and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view showing the general configuration of a first embodiment of the back-up spring device according to the invention, and FIGS. 2a and 2b are partial longitudinal cross-sectional views showing the general configuration of the second embodiment of the same. and a front view of a ring-shaped resin plate; FIG. 3 is a partial vertical sectional view showing the general configuration of a mechanical seal to which a conventional back-up spring device is applied; FIG. 4 is an enlarged view of the main parts of the same device. FIG. 1... Seal housing, 2... Seal flange, 3... Rotating shaft, 4... Stationary seal ring, 4
a... Stationary seal surface, 5... Rotating seal ring,
5a... Rotating seal surface, 6... Rotating operating ring,
8... Fixing bolt, 9... Space, 11... O ring, 12... Pressing ring, 15... Spring retainer, 16... Spring, 21... Backup spring member, 22... Metal backup ring , 23...Coating resin layer such as PTFE or TFE, 24...Ring-shaped resin plate such as PTFE or TFE, 25, 26...Gap, A...Low pressure side, B...High pressure side, P...Fluid liquid Pressure.

Claims (1)

[Claims for Utility Model Registration] (1) The sealing surfaces of both stationary and rotating seal rings are brought into contact with each other to form a rotating pressure sealing surface,
Furthermore, between the rotary seal ring or the rotary operation ring that holds the rotary seal ring and the rotary shaft, a back-up spring member and an O-ring are successively interposed on the inner end surface of the ring to form a stationary pressure seal surface. In a mechanical seal in which the inner circumferential side of the stationary seal ring is the low pressure side and the outer circumferential side of the rotating seal ring is the high pressure side, the back-up spring member is made of a metal having approximately the same coefficient of linear expansion, such as the rotating shaft. In addition, we have formed a resin layer such as PTFE or TFE with excellent thermal expansion resistance and low friction characteristics on both pressure-receiving end surfaces of this metal back-up spring, or provided a ring-shaped resin plate. Features mechanical seal back-up spring device. (2) The mechanical seal according to claim 1 of the utility model registration claim, characterized in that a resin layer such as PTFE or TFE is formed by coating on at least both end surfaces and the inner peripheral surface of a metal back-up spring. Backup spring device. (3) At least both end surfaces of the metal back-up spring should have a specified gap between them and the rotating shaft.
A back-up spring device for a mechanical seal according to claim 1, characterized in that a ring-shaped resin plate made of PTFE, TFE, etc. is disposed. (4) A back-up spring device for a mechanical seal according to claim 3, wherein a part of the ring-shaped resin plate is cut out at a predetermined gap.