JPH0771618A - Mechanical seal - Google Patents

Abstract

PURPOSE:To prevent roughening of the shaft seal surface or breakage of the fixed ring, by permitting a stationary ring and a rotary ring 10 to slide while in contact with each other during a low-speed rotation. CONSTITUTION:In a mechanical seal, shaft seal is performed while a rotary ring 10 is sliding against a stationary ring 11, and, on the other hand, an annular groove 14 is formed in a shaft seal surface of the stationary ring in a state of conducting to a high pressure side. In addition, a spiral groove 12b for transferring a fluid radially outwardly is formed in a shaft seal surface of the rotary ring. In this mechanical seal, the spiral groove is provided correspondingly from an inner-peripheral side to an outer-peripheral side of the annular groove 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical seal applied to a high speed, high pressure rotary fluid machine or the like.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view of a conventional mechanical seal used in a high speed, high pressure rotary fluid machine or the like. In the figure, in the present mechanical seal, a rotary ring 10 fixed to a rotary shaft 1 and a fixed ring 11 fixed to a casing 2 via a seal casing 3 slide with each other to form a shaft sealing surface. A seal is made between A and the low pressure side B. An annular groove 14 is provided on the shaft sealing surface of the fixing ring 11, and the annular groove 14
A communication hole 13 that connects the high pressure side A and the high pressure side A is provided.
On the shaft sealing surface of the rotating ring 10 corresponding to the surface on the high pressure side A in the radial direction defined by the annular groove 14 of the fixed ring 11, the fluid in the annular groove 14 is radially moved to the high pressure side A by the rotation of the rotating shaft 1. A plurality of spiral grooves 12a that move in the direction of are arranged side by side in the circumferential direction. The spiral groove 12a is a concave portion surrounded by two curved lines spirally extending from the center of the rotating ring 10 toward the outer periphery and two arcs parallel to the outer periphery of the rotating ring 10. In the drawings, reference numerals 4 and 5 are shaft sleeves, 7 is a pin, 8 is a spring, and 18 is a support ring.

[0003]

As described above, in the conventional mechanical seal, the plurality of spiral grooves 12a provided on the shaft sealing surface of the rotary ring 10 are formed on the shaft sealing surface of the fixed ring 11 by the rotation of the rotary shaft 1. The rotation shaft 1 is provided in a direction in which the fluid in the provided annular groove 14 is transferred to the high pressure side.
Rotation causes fluid in the annular groove 14 to be transferred in the spiral groove 12a, thereby increasing the fluid pressure in the gap between the sliding surfaces of both rings, and the axial pressure and high pressure acting on the fixed ring 11. It functions as a thrust bearing that keeps the rotating ring 10 and the fixed ring 11 from coming into contact with each other during rotation by balance with the fluid pressure on the side A. However, the force that hinders the contact between the rotating ring 10 and the fixed ring 11 generated by the function as the thrust bearing is substantially proportional to the rotation speed of the rotating shaft 1, so that both rings easily contact each other at low speed rotation. In particular, when the pressure on the high-pressure side A becomes higher, the force for bringing both rings into contact with each other increases due to the fluid pressure, so the number of rotations at which both rings can be kept in non-contact becomes high, and the number of rotations from the time of stop to the time of reaching that number There is a problem that the shaft sealing surface is roughened and the fixing ring 11 is damaged due to the contact and sliding of both rings at low speed rotation.

[0004]

SUMMARY OF THE INVENTION A mechanical seal according to the present invention is intended to solve the above problems. A rotary ring slides on a fixed ring to seal the shaft, and a high pressure side is applied to the shaft sealing surface of the fixed ring. In a mechanical seal provided with an annular groove in the circumferential direction which is continuous with and a spiral groove for transferring a fluid radially outward is provided on the shaft sealing surface of the rotating ring,
The spiral groove is provided so as to correspond to the inner peripheral side to the outer peripheral side of the annular groove.

[0005]

In the mechanical seal according to the present invention, the rotary ring slides on the fixed ring to seal the shaft, and the shaft sealing surface of the fixed ring is provided with an annular groove in the circumferential direction in conduction with the high pressure side. The shaft seal surface of the ring is provided with spiral grooves for transporting the fluid to the outside in the radial direction.The spiral groove in the mechanical seal is provided from the inner circumference side to the outer circumference side of the annular groove, and the shaft seal surface of the rotary ring. Since the spiral groove for transferring the fluid to the outer side in the radial direction is provided so as to face the outer peripheral portion to the inner peripheral portion of the annular groove of the fixing ring, the spiral groove located on the outer peripheral portion of the annular groove is the annular groove of the fixing ring. The fluid inside is transferred to the outside in the radial direction to function as a thrust bearing, and the spiral groove located on the inner peripheral portion of the annular groove is on the shaft sealing surface of the fixed ring even when the rotating ring and the fixed ring are in contact with each other. High pressure fluid in the annular groove It is introduced into the line groove to transfer the fluid spiral groove into an outer annular groove of the fixing ring by the rotation of the rotary shaft. As a result, the force acting in the direction of separating the fixed ring and the rotating ring increases.

[0006]

1 is an explanatory view of a mechanical seal according to an embodiment of the present invention. In the figure, the mechanical seal according to the present embodiment is used for a high-speed, high-pressure rotary fluid machine or the like, and includes a rotary ring 10 fixed to a rotary shaft 1.
The fixed ring 11 fixed to the casing 2 via the seal casing 3 slides on each other to form a shaft sealing surface, and seals between the high pressure side A and the low pressure side B. An annular groove 14 is provided on the shaft sealing surface of the fixed ring 11, and a communication hole 1 that connects the annular groove 14 and the high pressure side A to each other.
3 is provided. The shaft sealing surface of the rotating ring 10 corresponding to the annular groove 14 of the fixed ring 11 is provided with a plurality of spiral grooves 12b for discharging the fluid in the annular groove 14 in the radial direction toward the high pressure side A by the rotation of the rotating shaft 1. They are arranged side by side in the circumferential direction. The spiral groove 12b is a concave portion surrounded by two curved lines spirally extending from the center of the rotating ring 10 toward the outer periphery and two arcs parallel to the outer periphery of the rotating ring 10. In the figure, reference numerals 4 and 5 are shaft sleeves, 7 is a pin, 8 is a spring, and 18 is a support ring.

In the thrust bearing of the present invention, as shown in the figure, the high pressure in the radial direction of the shaft sealing surface divided into two in the radial direction by the annular groove 14 communicating with the high pressure side A provided on the shaft sealing surface of the fixed ring 11. From the shaft sealing surface of the rotary ring 10 corresponding to the shaft sealing surface of the side A to the shaft sealing surface of the rotary ring 10 corresponding to the shaft sealing surface of the fixed ring 11 on the low pressure side B radially divided by the annular groove 14 in the inner circumferential direction. A plurality of spiral grooves 12b are provided side by side in the circumferential direction. Symbols C-C and D-D in the drawings respectively indicate positions corresponding to the outer circumference and the inner circumference of the annular groove 14 provided on the shaft sealing surface of the fixed ring 11, and are arranged in the circumferential direction on the shaft sealing surface of the rotating ring 10. The plurality of spiral grooves 12b provided at the position are arranged starting from the outer peripheral side of the arc C-C and continuing to the inner peripheral side of the arc D-D.

In this way, the annular groove 14 of the fixing ring 10 is
By providing a plurality of spiral grooves 12b arranged in the circumferential direction on the shaft sealing surface of the rotary ring 10 corresponding to the outer peripheral portion to the inner peripheral portion of the rotary ring 10, the spiral groove 12b located on the outer peripheral portion of the annular groove 14 can be formed by the conventional method. Similar to the mechanical seal, the fluid in the annular groove 14 of the fixed ring 11 is transferred to the outer periphery and functions as a thrust bearing. Further, the spiral groove 12b located on the inner peripheral portion of the annular groove 14
Introduces the high-pressure fluid in the annular groove 14 of the fixed ring 10 into the spiral groove 12b even when the rotary ring 10 and the fixed ring 11 are in contact with each other, and the rotation of the rotary shaft 1 causes the high pressure fluid in the spiral groove 12b. The fluid is transferred toward the annular groove 14 of the outer fixed ring 11 to increase the fluid force acting in the axial direction so as to prevent the fixed ring 11 and the rotating ring 10 from coming into contact with each other.

In the conventional mechanical seal, the plurality of spiral grooves provided on the shaft sealing surface of the rotary ring transfer the fluid in the annular groove provided on the shaft sealing surface of the fixed ring to the high pressure side by the rotation of the rotary shaft. The fluid in the annular groove is transferred in the spiral groove due to the rotation of the rotating shaft, and the fluid pressure in the gap between the sliding shaft sealing surfaces of both rings rises to the fixed ring. The acting axial pressure balances with the fluid pressure on the high pressure side, and functions as a thrust bearing that keeps the rotating ring and the fixed ring from coming into contact with each other during rotation. However, the force that prevents the contact between the rotating ring and the fixed ring, which is generated by the function as the thrust bearing, is substantially proportional to the rotation speed of the rotating shaft, so that both rings easily contact each other at low speed rotation. In particular, when the pressure on the high pressure side becomes higher, the force that brings both rings into contact with each other increases due to the fluid pressure, so the number of rotations that can keep both rings out of contact increases, and the low speed from the time of stopping until reaching that speed. There is a problem that the shaft sealing surface is roughened or the fixed ring is damaged due to the contact and sliding of both rings during rotation, but in this mechanical seal, the shaft sealing surface of the rotating ring 10 is arranged in the circumferential direction. With multiple spiral grooves 12b
Is provided from a radial position that is larger than the outer diameter of the annular groove 14 of the fixed ring 11 to a radial position that is smaller than the inner diameter of the annular groove 14, so that the rotary ring 10 and the fixed ring 11 are in contact with each other. Even in the state, the high-pressure fluid in the annular groove 14 of the fixed ring 11 can be guided to the spiral groove 12b, particularly to the shaft sealing surface corresponding to the inner peripheral portion of the annular groove 14 of the fixed ring 11, so that the fixed ring 11 and the rotating ring 10 can be guided. It is possible to prevent the contact between both rings even at low speed rotation, in which the force in the direction for separating the and is increased as compared with the conventional case and the effect of the spiral groove 12b corresponding to the outer peripheral portion generated by the rotation as a thrust bearing is small. Further, at the time of high speed rotation, the spiral groove 12b corresponding to the outer peripheral portion acts as a thrust bearing, so that both rings are kept in non-contact state. At this time, the spiral groove 12b corresponding to the inner peripheral portion is the annular groove of the fixed ring 11. The fluid flowing from 14 to the inner peripheral side is pushed back to the outer peripheral side, and the amount of the fluid flowing out can be reduced.

[0010]

The mechanical seal according to the present invention is constructed as described above, and the force acting in the direction of separating the fixed ring and the rotating ring increases, so that both rings come into contact with each other at low speed rotation and slide. By doing so, it is possible to prevent the shaft sealing surface from being roughened and the fixing ring from being damaged.

[Brief description of drawings]

FIG. 1 (a) is a vertical sectional view of a mechanical seal according to an embodiment of the present invention, and FIG. 1 (b) is a front view of a rotating ring thereof.

FIG. 2 (a) is a vertical sectional view of a conventional mechanical seal, and FIG. 2 (b) is a front view of a rotating ring thereof.

[Explanation of symbols]

 1 rotating shaft 2 casing 3 seal casing 4 shaft sleeve 5 shaft sleeve 7 bin 8 spring 10 rotating ring 11 fixing ring 12b spiral groove 13 communication hole 14 annular groove 18 support ring A high pressure side B low pressure side

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kei Hashizume 2-1-1, Niihama, Arai-cho, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Takasago Plant

Claims (1)

[Claims] 1. A rotary ring slides on a fixed ring to seal the shaft, and a circumferential annular groove is provided on the shaft sealing surface of the fixed ring so as to be electrically connected to the high pressure side, and a fluid is applied to the shaft sealing surface of the rotary ring. A mechanical seal provided with a spiral groove that moves to the outside in the radial direction, wherein the spiral groove is provided from the inner peripheral side to the outer peripheral side of the annular groove.