JPH08219297A - Mechanical seal - Google Patents

Abstract

PURPOSE: To reduce the leakage of the fluid even under the condition of the high seal pressure difference by suppressing the deformation around a feed hole of a fixed ring when the high pressure is applied, and keeping the clearance between the slide surfaces small. CONSTITUTION: In a mechanical seal, a shaft seal surface is formed of a rotary ring 1 fixed to a rotary shaft and a fixed ring 2 to be pressed against the rotary ring to seal the space between a high pressure chamber 3 and a low pressure chamber 4. The mechanical seal is provided with a plurality of feed holes arranged in the circumferential direction on the shaft seal surface of the fixed ring so as to introduce the fluid, an annular groove 11 provided in the shaft seal surface of the rotary ring opposite to the feed holes, and a plurality of spiral grooves which are provided in the circumferential direction to the intermediate part between the annular groove and the outer circumferential part of the rotary ring and transfer the fluid in the annular groove in the outer circumferential direction as the shaft is rotated.

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 shaft seal portion of a high pressure rotating machine.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional mechanical seal, and FIG. 6 shows a surface view of a shaft sealing surface (sliding surface) of a rotary ring 1 shown in FIG. In these drawings, the mechanical seal forms a shaft sealing surface between the rotary ring 1 and the fixed ring 2 to seal between the high pressure chamber 3 and the low pressure chamber 4, and the rotary ring 1 is attached to the rotary shaft 5 as a pair. Shaft sleeves 6, 7
Fixed through. On the other hand, the fixed ring 2 is attached to the casing 8 surrounding the rotary shaft 5 via the seal housing 9 and the support ring 32, and is pressed toward the rotary ring 1 by the spring 10.

An annular groove 11 is provided on the shaft sealing surface of the fixing ring, and a plurality of communication holes 12 are provided in the circumferential direction of the fixing ring 2 for communicating the annular groove 11 with the high pressure chamber 3. Further, as shown in FIG. 6, at the portion of the shaft sealing surface of the rotating ring 1, the annular groove 1 of the fixed ring 2 is rotated by the rotation of the rotating shaft 5.
A plurality of spiral grooves 31 are provided in the circumferential direction for transporting the fluid in 1 toward the high pressure chamber 3 side.

Next, the acting force acting on the fixed ring 2 in the conventional example will be considered. The rotating ring 1 is rotated by the rotation of the rotating shaft 5.
The fluid pressure generated when the fluid in the annular groove 11 of the fixed ring 2 is transferred to the high pressure chamber 3 side by the plurality of spiral grooves 31 provided on the shaft sealing surface of the fixed ring 2 and the low pressure chamber from the annular groove 11 of the fixed ring 2. The fluid pressure flowing into 4 acts horizontally to the right from the shaft sealing surface in FIG.

The sum of the fluid force on the right rear surface of the fixing ring 2 and the force of the spring 10 acts leftward. That is, the axial movement is performed so that the sum of the fluid force acting from the fixed ring or the shaft sealing surface side and the sum of the fluid force acting from the rear surface and the force of the spring 10 become equal, and the axis of the rotating ring 1 and the fixed ring 2 The directional gap is determined.

[0006]

In the mechanical seal described above, in order to reduce the amount of fluid leaking from the high pressure chamber to the low pressure chamber side through the axial clearance between the rotary ring and the fixed ring, It is necessary to reduce the axial gap between the rings.

However, under a high seal differential pressure condition in which the pressure on the high pressure side is large, the amount of deformation of the rotary ring and the fixed ring due to the fluid pressure acting on the rotary ring and the fixed ring becomes large, and the gap between the sliding surfaces becomes small, for example ( 2 to 5 μm) is not possible.

In particular, in the fixed ring, the high-pressure fluid acting in the annular groove provided on the sliding surface causes the corners of the sliding surface to deform so as to protrude in the gap direction of the sliding surface. Therefore, under a high seal differential pressure condition, this corner portion comes into contact with the rotating ring during operation.

The purpose of the mechanical seal according to the present invention is to
It is an object of the present invention to provide a mechanical seal capable of suppressing the deformation around the supply hole of the fixed ring at the time of high pressure operation and keeping the gap of the sliding surface small to reduce the amount of fluid leakage even under the high pressure differential pressure condition.

[0010]

The mechanical seal of the present invention comprises a rotary ring 1 fixed to a rotary shaft and a fixed ring 2 pressed toward the rotary ring 1 by a spring 10 attached to a casing surrounding the rotary shaft. In a mechanical seal that forms a shaft sealing surface with and seals the high-pressure chamber 3 and the low-pressure chamber 4, a supply provided in the shaft sealing surface of the stationary ring in the circumferential direction to guide the fluid in the outer peripheral portion of the stationary ring to the shaft sealing surface. A hole 40, an annular groove 11 provided on the shaft sealing surface of the rotary ring 1 facing the supply hole, a plurality of annular shafts extending to an intermediate portion between the annular groove and the outer peripheral portion of the rotary ring 2 and provided in the circumferential direction. It is characterized by having a spiral groove 31 for transferring the fluid in the annular groove in the outer peripheral direction with the rotation of 5.

[0011]

Since the mechanical seal of the present invention is constructed as described above, the high pressure side fluid is supplied to the shaft of the fixed ring 2 and the rotary ring 1 by the plurality of supply holes 40 provided in the fixed ring 2 in the circumferential direction. It is introduced into the sealing gap and flows into the annular groove 11 provided in the rotating ring 1. The fluid in the annular groove 11 is rotated by the rotation of the rotating shaft, and when it is provided on the rotating ring 1, the rotating groove 31
The fluid pressure is increased by being transferred in the outer peripheral direction by.

The fluid in the annular groove 11 is the low pressure portion 4 on the inner peripheral side.
Flows into. Next, consider the lateral balance acting on the fixing ring 2. Then, the fluid pressure acting on the fixed ring 2 from the sliding surface is the fluid pressure acting from the gap between the outer peripheral portion and the inner peripheral portion of the annular groove 11, and the fluid force acting from the opposite sliding surface side of the fixed ring 2. The fixed ring 2 moves in the axial direction so that the four forces, which are the spring force and the spring force, are balanced, and the two rings 1, 2 are maintained in a non-contact state.

At this time, since the pressure deformation due to the high pressure in the supply hole 40 of the fixed ring 2 moves the annular groove provided in the conventional fixed ring to the rotating ring 1 side, the rigidity around the supply hole 40 in the fixed ring 2 is increased. The amount of deformation can be suppressed to a small value. Further rotating ring 1
In the newly provided annular groove 11, since the rotating ring is usually made of a high-rigidity material such as a ceramic material, the annular groove can be machined to a shallow (5-10) μm like a spiral groove. Therefore, the amount of deformation can be suppressed to a small amount, the pressure deformation of both rings can be reduced, the contact of both rings during rotation can be prevented, and the clearance of the sliding portion can be kept small.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is a sectional view of a mechanical seal according to a first embodiment of the present invention, and FIG. 3 is a sectional view of the rotating ring, and FIG. 4 is a sliding surface view of the rotating ring. In addition, in these figures, FIG.
The same parts as those of the conventional example shown in FIG.

The mechanical structure of the present invention comprises a rotary ring 1 fixed to a rotary shaft 5 and a fixed ring 2 pressed toward the rotary ring by a spring 10 mounted on a casing 8 surrounding the rotary ring 3 to form a high pressure chamber 3. And the low-pressure chamber 4 are sealed. In the present invention, the fixing ring 2 has a supply hole 4 for introducing the fluid in the high pressure chamber 3 on the outer periphery thereof to the shaft sealing surface.
A plurality of 0s are provided in the circumferential direction. An annular groove 11 having a width larger than the diameter of the supply hole 40 of the shaft sealing surface of the fixed ring 2 is provided on the shaft sealing surface of the rotating ring 1 facing the supply hole 40 of the shaft sealing surface. A plurality of spiral grooves 31 are provided on the sliding surface of the rotating ring 1 in the circumferential direction in the outer peripheral direction.

Next, the operation of the first embodiment will be described.
First, let us consider the balance of forces acting horizontally from the left and right of the fixing ring 2 in FIG. A fluid force generated by transferring the fluid to the outer peripheral side by the spiral groove 31 provided on the outer peripheral side of the annular groove 11 with respect to the shaft sealing surface side of both rings 1 and 2 by the rotation of the shaft, and the annular groove. On the inner peripheral side, the total of the fluid forces generated by reducing the pressure from the high pressure in the annular groove 11 to the low pressure in the low pressure chamber 4 acts.

On the back surface of the shaft-sealing surface of the fixing ring 2, the sum of the fluid force acting in the direction opposite to the fluid force and the force of the spring 10 pressing the fixing ring 2 through the support ring 32 acts. The axial position of the fixed ring is set by these forces, the two rings do not come into contact with each other, the gap between the sliding surfaces is kept small, and the amount of fluid leakage can be reduced even under the high pressure differential pressure condition.

[0018]

As described above, the plurality of supply holes 40 arranged in the circumferential direction are provided in the fixed ring, and the annular groove 11 of the rotary ring is provided at the position opposed to the supply holes 40. The deformation around the supply hole can be suppressed, and the amount of fluid leakage can be reduced even under the high pressure differential pressure condition. Furthermore, the annular groove provided on the rotating ring is provided inside the outer circumferential position of the supply hole, so that when the fluid in the annular groove flows to the inner circumferential side, the shaft sealing surface gap (circular groove depth) Since (+ the axial gap between the rotary ring and the fixed ring) changes to (the axial gap between the rotary ring and the fixed ring), it has a characteristic that it is easier to follow the change in the gap than the conventional seal.

[Brief description of drawings]

FIG. 1 is a sectional view of a mechanical seal according to a first embodiment of the present invention.

FIG. 2 is a view showing a shaft sealing surface of a rotary ring of the mechanical seal of the above.

FIG. 3 is a cross-sectional view of the above rotary ring.

FIG. 4 is a view showing a shaft sealing surface of the rotating ring of the above.

FIG. 5 is a diagram corresponding to FIG. 1 of a conventional example.

FIG. 6 is a corresponding diagram of FIG. 2 of a conventional example.

[Explanation of symbols]

1 ... Rotating ring, 2 ... Fixed ring, 3 ... High pressure chamber, 4 ... Low pressure chamber, 5 ... Rotating shaft, 6, 7 ... Shaft sleeve, 8 ... Casing, 9 ... Seal housing, 10 ... Spring, 11 ... Annular groove, 12 ... communication hole, 13 ... spiral groove, 32 ... support ring,
40 ... Supply hole.

Claims (1)

[Claims] 1. A rotating ring (1) fixed to a rotating shaft and a spring (1) attached to a casing surrounding the rotating shaft.
0) A mechanical seal that forms a shaft-sealing surface with a fixed ring (2) pressed against the rotary ring (1) to seal a high pressure chamber (3) and a low pressure chamber (4). The shaft sealing surface has a supply hole (4) arranged in the circumferential direction for guiding the fluid in the outer peripheral portion of the fixing ring (2) to the shaft sealing surface.
0), an annular groove (11) provided on the shaft sealing surface of the rotary ring (1) facing the supply hole, and extending in the circumferential direction to an intermediate portion between the annular groove and the outer periphery of the rotary ring (2). A mechanical seal having a plurality of spiral grooves 31 provided to transfer the fluid in the annular groove in the outer peripheral direction as the rotary shaft (5) rotates.