JPH07224948A - Mechanical seal - Google Patents

Abstract

PURPOSE:To constantly lubricate a mechanical seal sufficiently by guiding high pressure fluid into a lubrication guidance groove and forming a fluid film on the seal end by forming the lubrication guidance groove having its ends within an abutting range of the seal end and other end in the position displaced in the radial direction towards the high pressure fluid side from the abutting range. CONSTITUTION:When a rotary shaft 31 rotates, a rotational side seal ring 35 fixed to the rotary shaft 31 also rotates integratedly. A stationary side seal ring 55 fixed to a ring holder 53 is propelled rightwards as shown on the drawing by a compression spring 57 and pressed against the rotational side seal ring 35. An O ring 39 seals off the space between a casing 51 and the ring holder 53 arranged movably in the axial direction of the casing 51. In this case, high pressure fluid existing in the outside diameter of the sealed section advances into the inside of a lubrication guidance groove 35c, which is formed on the rotational side seal ring 35, from the section displaced in the outside diameter direction from an abutting range 35s of the lubrication guidance groove 35c. High pressure fluid is guided into the space between the seal ends of the abutting range 35c by relative rotational motion of the seal rings 35, 55 on both sides, so as to form a fluid film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical seal which is provided at a position where a rotary shaft of a rotary fluid machine penetrates a casing and seals fluid leakage, and more particularly to a dry sliding on a seal end surface of a seal ring. The present invention relates to a means for preventing abnormal wear and burnout due to.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional mechanical seal.
A rotary seal ring 35 is fixed to the rotary shaft 31 with a sleeve 33 inserted through an O-ring 39. A ring holder 53 is attached to the casing 51 via an O-ring 59 so as to be movable in the axial direction.
A stationary side seal ring 55 is integrally fitted to 3. A compression spring 57 and a rotation stop pin 56 are mounted between the casing 51 and the ring holder 53. The seal end surfaces of the rotary side seal ring 35 and the stationary side seal ring 55 are finished and assembled so as to be smooth surfaces that are perpendicular to the axis of the rotary shaft 31. Compression spring 5
7 pushes the ring holder 53 and the stationary seal ring 55 to the right in the figure, so that the seal end surface of the stationary seal ring 55 that does not rotate rotates the rotating seal ring 3
5 is pressed against the seal end surface of the rotary shaft 31 and the casing 51.
A tight seal is provided between and to prevent leakage of fluid.

[0003]

The conventional mechanical seal is as described above, but the fluid pressure becomes high and the pressing force of the stationary side seal ring 55 becomes high in order to prevent the leakage, and the rotating end face of the seal is rotated. When operating conditions become strict such as high speed, heat generation due to sliding of the seal part increases, and when the fluid to be sealed is water, for example, the water on the seal end face sliding part evaporates to dry. There is a problem that so-called dry sliding occurs and abnormal wear or seizure occurs.

The present invention has been made in order to solve the above-mentioned problems, and prevents the seal portion from being dry-sliding even under use conditions such as high seal pressure and high rotating peripheral speed. The purpose is to obtain a mechanical seal that prevents the occurrence of abnormal wear and seizure.

[0005]

In the mechanical seal according to the present invention, one end is in the contact range of the seal end face and the other end is in a position radially displaced from this contact range to the high-pressure fluid side. The guide groove is formed on the end face of the seal.

[0006]

The lubrication guide groove formed on the seal end surface of the mechanical seal according to the present invention has one end located within the contact range of the seal end surface and the other end located away from the contact range toward the high pressure fluid side. The high-pressure fluid flows into this groove from a portion outside the contact area of the lubrication guide groove, and the fluid that has flowed into this groove is drawn in between the seal end surfaces due to the relative rotational movement between the seal end surfaces, A fluid film is formed between the end faces of the seal. The interposition of this fluid film reduces solid contact between the seal end faces, and prevents abnormal wear and seizure of the seal faces. In this lubrication guide groove, the end opposite to the end outside the contact range is within the contact range of the seal end face and does not pass through the contact range in the radial direction. There is no increase in leakage of the seal end face through the guide groove.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B show a mechanical seal according to an embodiment of the present invention. FIG. 1A is a vertical sectional view and FIG. 1B is a plan view of a seal end surface. In FIG. 1, reference numeral 31 denotes a rotary shaft, and a rotary seal ring 35 is fixed to the rotary shaft 31 by inserting an O-ring 39, and a sleeve 33 is further fitted so that the rotary seal ring 35 is fixed to the rotary shaft 31. It is fixed to. A ring holder 53 is attached to the casing 51 via an O-ring 59 so as to be movable in the axial direction, and a stationary seal ring 55 is integrally fitted to the ring holder 53. Between the rear side of the ring holder 53 and the casing 51, the ring holder 53 and the stationary side seal ring 55 are provided.
Spring 5 for propelling the rotary seal ring 35 toward the rotary seal ring 35
7 and the rotation stop pin 56 for preventing the ring holder 53 and the stationary side seal ring 55 from rotating around. The rotating-side seal ring 35 may be made of high hardness steel or the like, and the stationary-side seal ring 55 may be made of carbon, ceramics, or a material such as fluororesin having a small friction resistance, which is suitable for use conditions. In the mechanical seal shown in FIG. 1, the outer diameter side of the seal portion is the high pressure fluid HP in the device, and the inner diameter side is the low pressure fluid LP such as air at atmospheric pressure.

As shown in FIG. 1, the rotating side seal ring 3
The end surface of the stationary seal ring 55 facing the stationary side seal ring 55 and the end surface of the stationary side seal ring 55 facing and contacting the rotating side seal ring 35 are finished as smooth surfaces that are exactly perpendicular to the axis of the rotary shaft 31. It is assembled. At the seal end surface of the rotary side seal ring 35, the lubrication guide groove 3
5c has been cut down. The lubrication guide groove 35c has a shape similar to an oil groove on the bearing surface and is formed in the radial direction in the length direction,
Eight pieces are arranged at equal intervals in the circumferential direction, for example, at intervals of 45 degrees. The lubrication guide groove 35c is formed so that the inner end thereof is in the contact range 35s and the outer end thereof is outside of the contact range 35s in the outer radial direction, that is, at the place deviated to the high-pressure fluid HP side.
The contact range 35s is a range in which the seal end surface of the stationary seal ring 55 contacts. The point in the contact area 35s where the inner end of the lubrication guide groove 35c is located is determined in consideration of the lubricity and the leak sealability described later.

Next, the operation of the embodiment shown in FIG. 1 will be described. When the rotary shaft 31 rotates, the rotary seal ring 35 fixed to the rotary shaft 31 also rotates integrally. On the other hand, the ring holder 53 is provided in the casing 51 so as to be movable in the axial direction, the stationary side seal ring 55 is fixed to the ring holder 53, and the compression spring 57 propels the ring holder 53 to the right in the drawing. The seal end surface of the stationary side seal ring 55 that does not rotate is pressed against the seal end surface of the rotating side seal ring 35 that rotates to seal fluid leakage. The O-ring 39 seals the leak between the rotary shaft 31 and the rotary seal ring 35, and the O-ring 59 seals the leak between the casing 51 and the ring holder 53. However, when the operating condition becomes strict such that the static pressure of the stationary side seal ring 55 is high due to the high fluid pressure and the rotational peripheral speed of the seal portion is high, conventionally, heat generation due to sliding of the seal portion increases, Due to the heat, the sliding portion of the seal end surface dries and becomes so-called dry sliding, resulting in abnormal wear and seizure.

On the other hand, in the mechanical seal shown in FIG. 1, a radial lubrication guide groove 35c is formed in the seal end surface of the rotary seal ring 35, and the inner end of the lubrication guide groove 35c is within the contact range 35s. Yes, since the outer end is located outside the contact area 35s in the outer diameter direction on the high pressure fluid HP side,
High-pressure fluid HP existing on the outer diameter side of the seal portion during operation
Is introduced into the lubrication guide groove 35c from a portion outside the contact range 35s of the lubrication guide groove 35c in the outer diameter direction. Due to the relative rotational movement with respect to the seal ring 55, it is drawn between the seal end faces of the contact area 35s like a lubricating oil of the bearing to form a fluid film. This fluid film reduces solid contact between the rotating side seal ring 35 and the stationary side seal ring 55, reduces frictional heat generation, and prevents occurrence of abnormal wear and seizure without so-called dry sliding.

As shown in FIG. 1, the inner end of the lubrication guide groove 35c is within the contact area 35s, and the lubrication guide groove 35c does not pass completely through the contact area 35s.
The high-pressure fluid that has entered the lubrication guide groove 35c does not flow from a position outside the outer diameter of s to escape to the inner diameter side of the contact area 35s, and the fluid leakage does not increase. Also,
The fluid between the sealing surfaces of the contact area 35s, particularly in the lubrication guide groove 35c, tends to be swung in the outer radial direction due to the centrifugal force generated by the rotation of the rotation side seal ring 35, and from this point as well. Fluid does not easily leak to the inner diameter side. In addition,
If the length of the lubrication guide groove 35c is increased so that the position of the inner end of the lubrication guide groove 35c is closer to the inner diameter side of the contact range 35s, the lubricity is improved but leakage may increase, so that the length is reduced. If the inner end position is shortened to a position closer to the outer diameter side within the contact range 35s, the leakage may be small but the lubricity may not be improved. Groove 3
It is necessary to determine the length of 5c and the position of its inner end. When the lubrication guide groove 35c is formed on the seal end face, in order to keep the balance due to the fluid pressure on the seal end face different from the conventional one, compared with the outer diameter of the ring holder 53 at the O-ring 59 portion. The radial position of the seal end face needs to be slightly outward.

Next, the embodiment shown in FIG. 2 will be described. The mechanical seal shown in FIG. 2 has a low pressure fluid LP on the outer diameter side and a high pressure fluid HP on the inner diameter side of the seal portion. The radial lubrication guide groove 35c formed in the seal end surface of the rotary seal ring 35 has an inner end located inwardly of the inner diameter of the contact range 35s, and an outer end in the contact range 35s.
Is formed to be inside. Therefore, during operation, the high pressure fluid HP existing on the inner diameter side of the seal portion is
The fluid that has entered the lubrication guide groove 35c from a portion of the lubrication guide groove 35c that is displaced from the contact area 35s toward the inner diameter direction, and the fluid that has entered the lubrication guide groove 35c is drawn between the seal end surfaces as described above. By forming a fluid film, solid contact between the rotating side seal ring 35 and the stationary side seal ring 55 is reduced, frictional heat generation is reduced, and abnormal wear and seizure are prevented. Further, since the outer end of the lubrication guide groove 35c is within the contact range 35s and does not completely pass through the contact range 35s, the high pressure fluid entering the lubrication guide groove 35c from the inner diameter side of the contact range 35s contacts. It does not flow out on the outer diameter side of the range 35s to escape, and the leakage of fluid does not increase.

The number and shape of the lubrication guide grooves 35c may be appropriately determined depending on the type of fluid to which the mechanical seal is applied, the pressure, the temperature, the design conditions such as the rotation speed of the rotary shaft 31, and the like. Further, in the embodiment described above, the narrow seal end face of the stationary seal ring 55 is in contact with the contact range 35s of the seal end face of the rotating seal ring 35, but conversely, the narrow rotating seal ring 35 is in contact.
In the case where the seal end surface of is in contact with the seal end surface of the wide stationary seal ring 55, the stationary seal ring 5
The above-mentioned lubrication guide groove may be formed on the seal end surface of No. 5.

[0014]

As described above, according to the present invention, the fluid that has entered the lubrication guide groove formed in the seal end face is drawn between the seal end faces to form a fluid film, and the solid contact of the seal end faces is prevented. Since the amount is reduced, frictional heat generation is reduced, and abnormal wear and seizure are prevented. Since the lubrication guide groove does not entirely pass through the contact area of the seal end face in the radial direction, leakage of fluid does not increase.

[Brief description of drawings]

1A and 1B show a mechanical seal according to a first embodiment of the present invention, FIG. 1A is a longitudinal sectional view, and FIG. 1B is a plan view of a seal end face.

2A and 2B show a mechanical seal according to a second embodiment of the present invention, FIG. 2A is a semi-longitudinal sectional view, and FIG. 2B is a partial plan view of a seal end face.

FIG. 3 is a vertical sectional view of a conventional mechanical seal.

[Explanation of symbols]

31: rotating shaft, 35: rotating side seal ring, 35c:
Lubrication guide groove, 35s: contact area, 51: casing,
53: ring holder, 55: stationary side seal ring,
57: compression spring, HP: high pressure fluid, LP: low pressure fluid.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yo Oni 1-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Plant (72) Keiomi Sakuma, Niihama, Niihama, Arai-cho, Takasago, Hyogo Prefecture No. 1 Mitsubishi Heavy Industries Takasago Plant

Claims (1)

[Claims] 1. A mechanical seal for sealing fluid leakage by bringing a seal end surface of a rotating side seal ring and a seal end surface of a stationary side seal ring into pressure contact with each other, wherein one of the seal end surfaces has one end of the seal end surface. A mechanical seal characterized in that a lubrication guide groove is formed in the contact range and the other end is radially displaced from the contact range to the high-pressure fluid side.