JPH09177990A - Mechanical seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an intended sealing performance and to enlarge an operation range having a constant floating up quantity (opening). SOLUTION: Fluid sent from a high pressure chamber enters an annular groove 2A through the connecting hole 12 of a fixed ring, and when the fluid is led into the spiral groove of a rotary ring, pressure in the spiral groove is risen by the rotation of the rotary ring to produce a prescribed floating up quantity (opening) in a sealed shaft part. In the case where pressure in the high pressure chamber is lower than a set value, a fixed ring 2 is pressed against a rotary ring on the side of the high pressure chamber by a spring 10 and a movable ring 22 to form the sealed shaft part 3A on an opposite face, but in the case where the pressure in the high pressure chamber is higher than the set value, the fixed ring moves against the spring, and is pressed against the rotary ring 1b on the side of a low pressure chamber to form a sealed shaft part 3B on mutually opposite faces. Thus the opening of the sealed shaft part 3A is compensated, and the intended sealing performance can be wholly obtained.

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 rotary device such as a gas compressor or a pump.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show an example of a conventional mechanical seal. In FIG. 3, a seal housing 9 is provided between the rotary shaft 5 and the inside of the stationary casing 8.
And a spring 1 is attached to the seal housing 9.
0 is attached, and by this spring 10, the movable ring 22
The fixed ring 2 and the fixed ring 2 are pressed in the direction of the rotary ring 1 to form a shaft sealing portion 3A of the fixed ring 2 with respect to the rotary ring 1, and the shaft sealing portion 3A seals between the high pressure chamber 3 and the low pressure chamber 4. Has been done.

A sleeve 6 and a sleeve 7 are attached to the rotary shaft 5, and the rotary ring 1 is supported on the rotary shaft 5 by the sleeves 6, 7. And the rotating ring 1
Is provided with a plurality of spiral grooves 31 for transferring the fluid to the high pressure chamber 3 side along the shaft sealing portion 3A. The fixed ring 2 and the movable ring 22 are provided with a plurality of communication holes 12 that connect the shaft seal portion 3A and the high pressure chamber 3 side, and the spiral groove 31 provided in the rotary ring 1 has a plurality of communication holes 12. Supplying fluid from. Further, the fixed ring 2 is provided with an annular groove 2A on the surface facing the rotary ring 1, and the annular groove 2A communicates with the communication hole 12.

The plurality of spiral grooves 31 provided in the rotating ring 1 allow the fluid on the high pressure chamber 3 side to pass through the communication hole 12 and the annular groove 2A by the rotation of the rotating ring 1 along the shaft sealing portion 3A. It is transferred in the radial direction and the pressure difference is maintained while allowing rotation between the rotary ring 1 and the shaft sealing portion 3A of the fixed ring 2. During the rotation, a gap of only a few μm is maintained by the action of the spiral groove 31. doing. In the spiral groove 31, when the rotating ring 1 rotates in the direction of the arrow as shown in FIG. 4, the flow direction of the fluid in the spiral groove 31 becomes an outward flow as shown by the arrow, and the fluid is transferred in the outer diameter direction. It becomes a so-called outward flow spiral groove.

[0005]

In the conventional mechanical seals shown in FIGS. 3 and 4, the radial length of the spiral groove 31 is increased in order to generate the load capacity required for the floating (opening) of the shaft sealing portion. Need to be long. However, since the radial length of the shaft sealing portion is limited, if the radial length of the spiral groove 31 is increased, the radial length of the sealing surface 32 becomes shorter.

For this reason, when it is attempted to obtain a predetermined flying height (several μm), the radial length of the sealing surface 32 becomes shorter as the radial length of the spiral groove 31 becomes longer.
There is a problem that the amount of fluid leaking from the sealing surface increases. In particular, when the high-pressure chamber 3 has a high pressure, this problem becomes remarkable, and as the opening of the shaft sealing portion 3A becomes larger, the predetermined floating amount and the leak amount become unbalanced, and the leak amount increases and the leak amount increases at the same time. There has been a problem that the shaft seal portion 3A becomes unstable, the floating amount of the shaft seal portion 3A is not constant, and the required performance as a mechanical seal cannot be secured.

The present invention has been proposed in view of the above problems, and an object of the present invention is to provide a mechanical seal which has a predetermined sealing performance and has a large flying range (opening) and a large operating range. And there is a point.

[0008]

In order to achieve this object, the mechanical seal of the present invention comprises a high pressure chamber side rotary ring and a low pressure chamber side rotary ring which are mounted on a rotary shaft at intervals, and the respective rotary rings. The surrounding seal housing, the fixed ring arranged between the rotary rings, and the spring attached to the seal housing move in the direction of the high pressure chamber side rotary ring to press the fixed ring against the high pressure chamber side rotary ring. A movable ring is provided, and an annular groove is provided in the shaft sealing portion of the fixed ring with respect to the high-pressure chamber side rotating ring, and a plurality of communication holes that connect the annular groove and the high-pressure chamber side are provided in the fixed ring. A plurality of spiral grooves for transferring fluid along the circumferential direction are provided on the surface of the low pressure chamber side rotating ring facing the fixed ring, and the difference between the pressure on the high pressure chamber side and the spring force is provided. Forming a shaft seal part between each other more pressing the fixing ring to the high pressure chamber side rotating ring.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a mechanical seal of the present invention will be described with reference to an embodiment shown in FIGS. 1 and 2, the same parts as those of the conventional mechanical seals of FIGS. 3 and 4 are designated by the same reference numerals. Figure 1 is a vertical side view of this mechanical seal. 3 is a high pressure chamber, 4 is a low pressure chamber,
In order to seal the space between the high pressure chamber 3 and the low pressure chamber 4, the mechanical seal is provided between the rotary shaft 5 and the seal housing 9 inside the casing 8. That is, the high pressure chamber side rotating ring 1a and the low pressure chamber side rotating ring 1b are sandwiched between the spacer 7A, the sleeve 6 and the sleeve 7, and are supported on the rotating shaft 5 with a space therebetween. A fixed ring 2 is disposed between the high-pressure chamber side rotary ring 1a and the low-pressure chamber side rotary ring 1b so as to be capable of minute movement in the axial direction. The fixed ring 2 is attached to a seal housing 9 to form a spring 1.
0 and the movable ring 22 are pressed against the high-pressure-chamber-side rotating ring 1a, and the fixed ring 2 has the high-pressure-chamber-side rotating ring 1a.
A shaft sealing portion 3A for the shaft is configured.

The shaft sealing portion 3A of the high pressure chamber side fixing ring 2 is provided with an annular groove 2A, and a plurality of communication holes 12 communicating with the annular groove 2A and the high pressure chamber 3 are provided in the outer diameter direction. Has been. A plurality of spiral grooves 31 (see FIG. 4) are circumferentially provided in the shaft sealing portion 3A of the high-pressure chamber-side rotary ring 1a, and the high-pressure chamber-side rotary ring 1a is rotated clockwise (arrow in FIG. 4). The fluid in the annular groove 2A is guided to the spiral groove 31 and the outward flow is generated.

Further, the shaft sealing portion 3B of the rotary ring 1b on the low pressure chamber side
A plurality of spiral grooves 31 (see FIG. 4) similar to the above are provided in the circumferential direction of the low pressure chamber side rotary ring 1b.
Rotates in the counterclockwise direction (the direction opposite to the arrow in FIG. 4), the fluid flowing from the high-pressure chamber 3 is guided to the spiral groove 31 and an inward flow is generated. When the groove direction of the spiral groove 31 is provided in the direction opposite to that of FIG. 4 and the counterclockwise rotation is performed like the above-described rotary ring, the fluid guided to the spiral groove 31 becomes an outward flow.

Next, the operation of the mechanical seal shown in FIGS. 1 and 2 will be specifically described. 2A and 2B show the moving state of the fixed ring 2 of the mechanical seal. Fluid from the side of the high pressure chamber 3 has a communication hole 12 of the fixed ring 2.
And enters the annular groove 2A. Then, the fluid from the annular groove 2A is guided to the spiral groove 31 of the rotating ring, and the outward flow spiral groove 3
The pressure in 1 is increased, and a predetermined floating amount (opening) is obtained on the shaft sealing portion 3A.

In a normal case (when the pressure on the side of the high pressure chamber 3 is lower than the set value), the fixed ring 2 is moved to the left (see FIG. 2) by the spring 10 and the movable ring 22 as shown in FIG.
(A) in the direction of the dotted line arrow) and is pressed against the high pressure chamber side rotating ring 1a to form shaft sealing portions 3A on the surfaces facing each other, and the fluid from the high pressure chamber 3 side is fixed in the fixing ring 2. When entering the annular groove 2A via the communication hole 12, the fluid from the annular groove 2A is guided to the spiral groove 31 of the high pressure chamber side rotating ring 1a by the rotation of the high pressure chamber side rotating ring 1a, and an outward flow is generated, The pressure in the spiral groove 31 is increased, and a predetermined floating amount (opening) is obtained on the shaft sealing portion 3A.

When the pressure on the side of the high pressure chamber 3 increases due to the operating conditions, the fixing ring 2 resists the pressing force of the spring 10 to the right (see FIG. 2 (b), as shown in FIG. 2 (b)). b) in the direction of the dotted line arrow) and pressed against the low pressure chamber side rotating ring 1b to form shaft seal portions 3B on the surfaces facing each other, and the fluid from the high pressure chamber 3 side passes through the gap to the low pressure chamber side. It flows in the direction of the rotating ring 1b.

Then, by the rotation of the low pressure chamber side rotating ring 1b, it is guided to the spiral groove 31 of the low pressure chamber side rotating ring 1b,
An inward flow or an outward flow is generated, the pressure in the spiral groove 31 is increased, and a predetermined floating amount is obtained on the shaft sealing portion 3B. Therefore, even if the pressure on the high-pressure chamber side becomes high, an appropriate shaft seal portion is formed on the low-pressure chamber side, so the leak amount decreases,
The sealing performance is stable.

According to the present invention, since the fixing ring 2 is moved in the axial direction by the pressure on the high pressure chamber side to form a proper shaft seal portion as described above, the leak amount is small even if the pressure changes. The sealing performance is stable. In the above embodiment, the outward flow spiral groove 31 is provided on the rotating rings 1a, 1b side, but the outward flow spiral groove 31 is provided on the fixed ring 2.
Even if it is provided on the side, the same operation is performed.

[0017]

The mechanical seal of the present invention is constructed as described above, and a plurality of spiral grooves provided in the shaft sealing portion of the rotary ring are mounted on the rotary shaft with fluid from the annular groove provided in the fixed ring. By rotating the rotary ring to transfer it to the high-pressure chamber side, it functions as a thrust bearing.
In this spiral groove, the fluid from the high pressure chamber enters the annular groove through the communication hole of the fixed ring, the fluid from the annular groove is guided to the spiral groove of the rotating ring, the pressure in the spiral groove is increased, and A predetermined floating amount (opening) is obtained in the sealed portion. Then, in a normal case (when the pressure in the high pressure chamber is lower than the set value), the fixed ring 2 is pressed against the high pressure chamber-side rotating ring by the spring and the movable ring, and the shaft sealing portion 3A is provided on the mutually opposing surfaces. However, when the pressure in the high pressure chamber becomes higher than the set value due to the operating conditions, the fixed ring moves against the spring and is pressed against the low pressure chamber side rotating ring to face each other. Since the shaft seal portion 3B is formed on the surface, even if the pressure on the high pressure chamber side becomes high, the floating amount (opening) of the shaft seal portion on the high pressure chamber side becomes large, but the shaft on the low pressure chamber side becomes large. Since the proper shaft seal part is formed in the seal part, the leak amount does not increase,
The leak amount is stable and the desired sealing performance is obtained.

Further, even if the pressure in the high pressure chamber becomes high, the fixed ring moves to form a proper shaft seal portion, so that the leak amount is stable even if the pressure changes, and the fluid leaks from the seal surface. It is possible to provide a mechanical seal that has a small flying height and a large operating range with a constant flying height (opening).

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a mechanical seal of the present invention.

FIG. 2A and FIG. 2B are explanatory views of the operation of the mechanical seal.

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

FIG. 4 is a front view showing a spiral groove provided in a rotary ring of the mechanical seal.

[Explanation of symbols]

 1 rotating ring 1a high pressure chamber side rotating ring 1b low pressure chamber side rotating ring 2 fixed ring 2A annular groove 3 high pressure chamber 3A, 3B shaft seal part 4 low pressure chamber 5 rotating shaft 6 sleeve 7 sleeve 8 casing 9 seal housing 10 spring 12 communication hole 22 movable ring 31 spiral groove

Claims (1)

[Claims] 1. A high-pressure chamber-side rotary ring and a low-pressure chamber-side rotary ring mounted on a rotary shaft at intervals, a seal housing surrounding each rotary ring, and a fixed ring arranged between the rotary rings. A movable ring that moves in the direction of the high pressure chamber side rotating ring by a spring attached to the seal housing to press the fixed ring against the high pressure chamber side rotating ring, and the shaft of the fixed ring with respect to the high pressure chamber side rotating ring. An annular groove is provided in the sealing portion, and a plurality of communication holes that connect the annular groove and the high pressure chamber side are provided in the fixed ring, and the rotation direction of the low pressure chamber side rotary ring faces the fixed ring in the circumferential direction. A plurality of spiral grooves for transferring the fluid are provided, and the fixed ring is pressed against the high-pressure chamber-side rotating ring by a difference between the pressure on the high-pressure chamber side and the spring force, and an axis is provided between them. A mechanical seal characterized by having a sealed portion.