JPH0756344B2 - mechanical seal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical seal for sealing a shaft by relatively rotating two sealing rings in a contact state or in a non-contact state via a fluid film.

[0002]

2. Description of the Related Art In a conventional mechanical seal of this type, for example, as shown in FIG. 14, a retainer 14 is fixed to a rotary shaft member 11 and a rotary seal ring member 15 is fitted, and a casing 12 is made of carbon or the like. Stationary seal ring 1
A stationary seal ring member 13 provided with 3b is held so as to be slidable in the axial direction, and the stationary seal ring member 13 is attached to the coil spring 1
The rotary seal ring member 15 is pressed and biased by the switch 8.
The rotary shaft member 11 is formed by fitting a metal sleeve 11b onto the rotary shaft 11a, and the retainer 14 is integrally formed with the sleeve 11b. The rotary seal ring member 15 comprises a metallic reinforcing ring 1 on the outer periphery of a rotary seal ring 15a made of ceramics such as silicon carbide or cemented carbide such as tungsten carbide.
5b is shrink-fitted. The rotary seal ring 15a is held by the retainer 14 in a relatively non-rotatable manner by engaging a drive pin 16c (or key) attached to the retainer 14 side with a pin hole 16b (or key groove) formed in the rotary seal ring 15a. The rotary shaft 11a is rotated in accordance with the rotation of the rotary shaft 11a, and seals the fluid to be sealed by the relative rotating action with the stationary seal ring 13a facing the rotary shaft 11a. In the contact type seal, both seal rings 13
The sealed end faces, which are the opposite end faces of a and 15a, are pressed and contacted by the coil spring 18. On the other hand, in the non-contact type seal, a dynamic pressure generating groove is formed in the sealing end surface of the rotary seal ring 15a to generate a dynamic pressure between both sealing end surfaces, so that a fluid film is interposed between the sealing end surfaces. It is designed to be held in contact.

Further, between the inner peripheral surface of the rotary seal ring 15a and the outer peripheral surface of the sleeve 11b, a so-called tolerance is obtained by press-molding a thin band plate material made of stainless steel into a corrugated cross-section. The ring 17 is loaded, and the rotary seal ring 15a is biased and held concentrically with the rotary shaft member 11 by the radial elastic force of the tolerance ring 17. In other words, with the tolerance ring 17,
The rotary seal ring 51 is automatically centered.

Therefore, when the mechanical seal is assembled or the rotary seal ring 5a is replaced, the rotary seal ring 5a can be easily centered with respect to the rotary shaft member 1, and the rotary seal ring member 1 can be easily assembled. You can do it. Even during operation, the rotary seal ring 15a keeps the tolerance ring 1
7, the centering is performed automatically, and the radial positional relationship between this and the stationary seal ring 13b is properly maintained, and a good sealing function is exhibited.

[0005]

However, the sleeve 11b made of metal and the rotary seal ring 15a made of ceramics or the like are used.
The coefficient of thermal expansion differs greatly between and, so that the rotary seal ring 15a (or the sleeve 11) may vary depending on the operating conditions of the equipment.
If the temperature in b) rises, both 11b and 15
The tolerance ring 17 may be crushed due to the difference in the amount of thermal expansion of a. When the tolerance ring 17 is crushed as described above, a force (tensile stress) for expanding the inner diameter of the rotary seal ring 15a acts on the inner peripheral surface of the rotary seal ring 15a. Coupled with the fact that the constituent ceramics and the like are brittle materials that are weaker in tensile stress than in compressive stress, the rotary seal ring 15a may be damaged, and a good and stable sealing function may be provided for a long period of time. There was a problem that I could not expect.

Incidentally, the sleeve 11b and the rotary seal ring 15a
While a mechanical seal in which an O-ring is loaded instead of the tolerance ring 17 has been proposed, the O-ring has a lower deflection than the tolerance ring 17, and the amount of deflection is saturated. A highly accurate self-centering function like the tolerance ring 17 cannot be expected at all, and when the weight of the rotary seal ring 15a is large, the rotary seal ring 1 is used.
Since 5a is eccentric, a good sealing function cannot be exhibited.

The present invention solves such a problem and provides a mechanical seal capable of exhibiting a good and stable sealing function over a long period of time regardless of whether it is a contact type or a non-contact type. It is intended.

[0008]

MEANS FOR SOLVING THE PROBLEMS The mechanical seal of the present invention which has solved this problem, in particular, fixes a metal retainer having an annular holding surface concentric therewith to a rotary shaft member,
A rotary seal ring member, which is composed of a rotary seal ring made of ceramics or cemented carbide and a metal reinforcing ring shrink-fitted to the outer periphery of the retainer, is relatively unrotatable in a state of being loosely fitted to the rotary shaft member. A ring-shaped or arc-shaped spring member having elasticity in the radial direction is held between the ring-shaped holding surface and the outer peripheral surface of the reinforcing ring to urge and hold the rotary seal ring member in a concentric state with the rotary shaft member. It is loaded.

[0009]

The rotary seal ring member is automatically aligned with the rotary shaft member (directly, with respect to the annular holding surface concentric with the rotary shaft member) by the spring member. Since this spring member is loaded between the metal retainer and the reinforcing ring, it is not crushed by the difference in thermal expansion amount and can exhibit a good self-centering function. In addition, since the radial direction of the rotary seal ring member is held by the spring member on the outer peripheral side of the rotary seal ring member, the inner diameter of the rotary seal ring can be made larger than the outer diameter of the rotary shaft member. Therefore, it is possible to reliably prevent tensile stress from being generated on the inner peripheral surface of the rotary seal ring due to the difference in thermal expansion between the two. Therefore, the rotary seal ring is not distorted or damaged, and a good sealing function can be exhibited for a long period of time regardless of the mechanical seal type (contact type, non-contact type) or the operating conditions of the equipment. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be specifically described below based on the embodiments shown in FIGS. In the mechanical seal shown in FIG. 1, 1 is a rotary shaft member that penetrates the casing 2, 3 is a stationary seal ring member held by the casing 2,
4 is a retainer fixed to the rotary shaft member 1, 5 is a rotary seal ring member loosely fitted in the rotary shaft member 1, 6 is a torque transmission mechanism interposed between the retainer 4 and the rotary seal ring member 5, 7
Is a spring member mounted between the retainer 4 and the rotary seal ring member 5.

The rotary shaft member 1 is formed by fitting a metal sleeve 1b on the rotary shaft 1a. The stationary sealing ring member 3 is composed of a holding ring 3a held slidably in the casing 2 in the axial direction and a stationary sealing ring 3b internally fitted and fixed to the holding ring 3a, and is inserted between the holding ring 3a and the casing 2. A plurality of (only one is shown) coil springs 8 are pressed and urged toward the rotary seal ring member 5.

As shown in FIG. 1, the retainer 4 is made of metal integrally formed with the sleeve 1b and has an annular wall portion 4a and a tubular portion 4b. The inner peripheral surface of the tubular portion 4b is formed as an annular holding surface 4c that is concentric with the rotary shaft member 1.

As shown in FIG. 1, the rotary seal ring member 5 includes a rotary seal ring 5a made of ceramics such as silicon carbide or cemented carbide such as tungsten carbide, which is inserted in the sleeve 1b, and a metal which is shrink-fitted on the outer periphery thereof. It is made of a reinforcing ring 5b. The rotary seal ring 5a is held in contact with the annular wall portion 4a of the retainer 4 by the sleeve retainer 1c, and an O-ring 9 is interposed in the contact portion. Rotating seal ring 5a
Has an inner diameter set to be larger than the outer diameter of the sleeve 1b by an appropriate amount so that the sleeve 1b can be easily assembled into the rotary shaft member 1 and stress due to a difference in thermal expansion between the two 1b and 5a is not generated. Has been done.

As shown in FIGS. 2 and 3, the torque transmission mechanism 6 includes the inner peripheral portion of the annular tubular portion 4b of the retainer 4 and the reinforcing ring 5.
By engaging a parallel key 6c having a rectangular cross section with the key grooves 6a and 6b formed on the outer peripheral portion of b, torque transmission from the rotary shaft member 1 to the rotary seal ring member 5 is performed. The key grooves 6a, 6b and the key 6c are preferably provided at a plurality of locations at equal intervals in the circumferential direction, and in this embodiment, they are provided at two locations facing each other in the radial direction. As shown in FIGS. 12 and 13, a round rod-shaped pin 6d may be used instead of the key 6c. Of course, the retainer 4 and the reinforcing ring 5b may be directly engaged with the concave and convex without interposing the key 6c or the pin 6d. By the way, as shown in FIG. 14, the rotary seal ring 15a
When the pin hole 16b and the key groove are formed in the pin hole 16b and the like, since the constituent material of the rotary seal ring 15a is a super-hard brittle material such as ceramics, it is of course difficult to process the pin hole 16b and the like. There is a possibility that a crack may occur in the portion where the pin hole 16b and the like are formed due to stress concentration, and the rotary seal ring 15a may be damaged. However, as described above, the retainer 4 and the reinforcing ring 5
If b is to be engaged indirectly or directly via the key 6c or the pin 6d, such a problem does not occur at all.

As shown in FIGS. 4 to 7, the spring member 7 is formed by pressing a thin band plate material made of stainless steel or the like into a corrugated cross-section having bulged portions 7a ... Is cut into pieces and curved in an arc shape or an annular shape so that the bulging portions 7a are located inside, and the annular holding surface 4c and the reinforcing ring 5b of the retainer 4 are pressed with the bulging portions 7a.
It is loaded between the outer peripheral surface of the bulge portion 7a, ...
Due to the elastic force in the radial direction, the rotary shaft member 5 is biased and held in a concentric state with respect to the annular holding surface 4c and thus the rotary shaft member 1. In this embodiment, as shown in FIG. 1 and FIG. 2 or FIG. 12, in the annular gap between the annular holding surface 4c and the outer peripheral surface of the reinforcing ring 5b, an arc shape excluding the installation positions of the keys 6c, 6c or the pins 6d, 6d. A pair of spring members 7, 7 curved in a substantially semi-circular shape are loaded in the portions with the inner peripheral portions thereof being engaged with the annular groove 5c formed in the outer peripheral portion of the reinforcing ring 5b. .

Therefore, the self-aligning function of the spring members 7, 7 makes it possible to easily perform the centering work of the rotary seal ring 5a when assembling the mechanical seal or replacing the rotary seal ring member 5. Inside, both sealing rings 3
It is possible to maintain a proper radial positional relationship between b and 5a and exert a good sealing function. Moreover, since the spring members 7 and 7 are loaded between the metal retainer 4 and the metal reinforcing ring 5b, they are crushed by the difference in thermal expansion amount between the two even under high temperature conditions. Therefore, the self-centering function of the spring members 7 is not impaired. Further, radial holding of the rotary seal ring member 5 by the spring members 7, 7 is performed on the reinforcing ring 5b side, and between the inner peripheral surface of the rotary seal ring 5a and the outer peripheral surface of the sleeve 1b,
Since the filling such as the tolerance ring 17 does not intervene and the sufficient space 10 is secured, the rotary seal ring 5a is not distorted or damaged due to the difference in thermal expansion amount between the two 1b and 5a, and the contact type In that case, a good sealing function is exhibited regardless of the non-contact type.

By the way, the spring member 7 of the above embodiment has substantially the same shape as the tolerance ring 17 described at the beginning, but by forming the spring member 7 into a shape as shown in FIGS. It is possible to provide a mechanical seal that is more excellent in terms of functions and the like.

That is, this spring member 7 is shown in FIGS.
As shown in FIG. 1, it has a shape in which a portion between the adjacent bulged portions 7b, 7b is cut out, and has a shape as compared with that of the above-mentioned embodiment.
Due to the presence of the cutouts 7c, the bending property as a whole and the elasticity of the bulging portions 7b, and thus the self-centering property can be significantly improved. Therefore, the spring member 7 having such a shape
By using, the loading between the retainer 4 and the reinforcing ring 5b can be performed more easily, and the balance between the sealing rings 3b and 5a during operation can be significantly improved. Concretely, the "grade of good balance" referred to in JIS B0905 is G
It can be 2.5 or less.

[0019]

As is apparent from the above description, according to the present invention, even when a large thermal expansion difference occurs between the rotary shaft member and the rotary seal ring due to the operating conditions of the equipment, the spring The centering function of the rotary seal ring member is not impaired, and the rotary seal ring made of brittle material is not distorted or damaged. Therefore, in both the contact type and the non-contact type, a good and stable sealing function can be exerted for a long period of time.

[Brief description of drawings]

FIG. 1 is a half-section vertical side view showing an embodiment of a mechanical seal according to the present invention.

FIG. 2 is a vertical cross-sectional front view of the seal (a cross section taken along line II-II in FIG. 1).

FIG. 3 is a cross-sectional view showing a main part of the seal (the cross-section is II in FIG. 2).
It is along the line I-III).

FIG. 4 is a development view of a main part (spring member) of the seal.

5 is a sectional view taken along line VV of FIG.

6 is a sectional view taken along line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

8 is a partially cutaway sectional view corresponding to FIG. 2 showing a modified example of the torque transmission mechanism.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a developed plan view showing a modified example of the spring member.

11 is a sectional view taken along line XI-XI of FIG.

12 is a sectional view taken along line XII-XII in FIG.

13 is a sectional view taken along line XIII-XIII in FIG.

FIG. 14 is a vertical cross-sectional side view showing a conventional mechanical seal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating shaft member, 4 ... Retainer, 4c ... Annular holding surface, 5
... Rotary seal ring member, 5a ... Rotary seal ring, 5b ... Reinforcement ring,
6 ... Torque transmission mechanism, 7 ... Spring member.

Claims (1)

[Claims] 1. A metal retainer having an annular holding surface concentric with the rotary shaft member is fixed to the rotary shaft member, and the retainer is fixed to the rotary shaft member.
A rotary sealing ring member comprising a rotary sealing ring made of ceramics or cemented carbide and a metal reinforcing ring shrink-fitted to the outer periphery of the rotary sealing ring member is held in a relatively non-rotatable state while being loosely fitted to the rotary shaft member, Between the annular holding surface and the outer peripheral surface of the reinforcing ring, a ring-shaped or arc-shaped spring member having elasticity in the radial direction is loaded so as to urge and hold the rotary sealing ring member in a concentric state with the rotary shaft member. Characteristic mechanical seal.