JPH10281300A - Mechanical seal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain high sealing performance even at low speed rotation and prevent sliding deterioration of a sealing surface even in the case of low fluid supply pressure by providing a spiral groove to face on a ring groove of a fixed ring on a shaft seal part of a rotary ring and providing a circumferential groove on the outer peripheral side of the spiral groove. SOLUTION: A plural number of spiral grooves 31 are provided on a shaft seal part 3A of a rotary ring 1 and more than one circumferential grooves 3B and a bank part 3C are provided on the outside of them. Fluid from a high pressure chamber 3 enters a ring groove 2A of a fixed ring 2 through a communicating hole 12, led to the inside of the spiral grooves 31 and generates dynamic pressure in the spiral grooves 31 by rotation of the rotary ring 1. Thereafter, fluid runs over the bank part 3C from the extreme outer periphery of the spiral grooves 31 and flows in the circumferential grooves 3B. Hereby, flow of fluid in the radial direction is disturbed, and high static pressure is generated. It is possible to provide specified floating quantity of the shaft seal part 3A even by low speed rotation by combining dynamic pressure in the spiral grooves 31 and static pressure in the circumferential grooves 3B. Additionally, it is possible to float the shaft seal part 3A by low speed rotation even in the case when supply pressure of fluid is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mechanical seal device used for a rotary shaft of a rotary machine such as a gas compressor or various pumps.

[0002]

2. Description of the Related Art In a gas compressor, various pumps for sending a high-pressure fluid, etc., a mechanical seal device is used because an operating or operating fluid has a relatively high pressure and a more reliable shaft sealing effect is required. 5 and 6 show a conventional example of a mechanical seal device for such a rotary machine. FIG. 5 is a cross-sectional view (upper half of the axis) along the axis of the rotary machine, and FIG. 6 is a front view of the rotary ring. .

In FIGS. 5 and 6, reference numeral 5 denotes a rotating shaft which is connected to a driving source such as a motor (not shown) and rotates. Reference numeral 8 denotes a casing of a rotary machine. An annular seal housing 9 is fixed to the casing 8 by fitting an outer periphery 9 a of the seal housing 9 into the fitting hole 8 a of the casing 8.

A rotating ring 1, a fixed ring 2, and a movable ring 22 are arranged inside the annular seal housing 9 in the axial direction. Reference numeral 10 denotes a spring provided between the seal housing 9 and the side surface of the movable ring 22. A plurality of springs 10 are provided along the circumferential direction to press the movable ring 22 and the fixed ring 2 toward the rotating ring 1 side. I have.

[0005] Due to the pressing force from the spring 10, a shaft sealing portion 3A which slides in the circumferential direction is formed between the side surface of the fixed ring 2 and the side surface of the rotating ring 1 opposed thereto. High-pressure chamber 3 for storing high-pressure gas, high-pressure oil, etc.
And a low pressure chamber 4 such as the atmosphere.

[0006] A sleeve 6 and a sleeve 7 are attached to the rotating shaft 5, and the rotating ring 1 is supported on the rotating shaft 5 via the sleeves 6 and 7. Then, as shown in FIG.
Spiral groove 3 for transferring fluid to the high pressure chamber 3 side along
1 are provided at equal intervals in the circumferential direction.

In the axial direction of the fixed ring 2 and the movable ring 22, a plurality of communication holes 12 for connecting the shaft sealing portion 3A and the high pressure chamber 3 side are provided.
The gas on the high pressure chamber 3 side is introduced into the spiral groove 31. The fixed ring 2 is provided with an annular groove 2 </ b> A on a surface facing the rotating ring 1.
A is connected to the communication hole 12. 5a is a step portion of the rotating shaft 5, 6a is a front surface of the sleeve 6 abutting on the step portion 5a, and 21, 23, 24, 25, 26, 27 are O-rings.

During operation of a rotary machine equipped with such a conventional mechanical seal device, a plurality of helical grooves 31 provided at equal intervals in the circumferential direction on the rotary ring 1 are provided in a high-pressure chamber by rotation of the rotary ring 1. 3 side fluid through communication hole 1
2 and the outer circumferential direction along the shaft sealing portion 3A via the annular groove 2A. Then, a pressure difference is maintained between the shaft sealing portions 3A of the rotating ring 1 and the fixed ring 2 while allowing relative rotation. Of small gaps (intervals).

As shown in FIG. 6, the spiral groove 31 is formed by a so-called outward-flow spiral groove 31 that can transfer a fluid in an outer radial direction when the rotating ring 1 rotates. When the gap, that is, the floating rotation speed for obtaining a predetermined floating amount (several μm) is high, and especially when the introduction pressure on the high pressure chamber 3 side is low, the floating rotation speed is extremely high. Here, the predetermined floating amount indicates a floating amount at which the rotating ring 1 and the fixed ring 2 do not come into mechanical contact with each other. That is, the surfaces of the rotating ring 1 and the fixed ring 2 are processed with extremely high finishing accuracy, but the surfaces of the rotating ring 1 and the fixed ring 2 are extremely small until reaching a predetermined floating amount (floating rotation speed). Contact sliding.

[0010]

In such a conventional mechanical seal device, as described above, the floating rotation speed for generating a load capacity required for a predetermined floating amount (opening) of the shaft sealing portion 3A is reduced. It was extremely high. For this reason, in the related art, when the starting and stopping of the rotating machine is repeated, the sealing surface 32 of the shaft sealing portion 3A is slidably deteriorated at a low speed equal to or lower than the floating rotation speed, and the sealing performance is deteriorated. There has been a problem that reliability is reduced.

As described above, when the supply pressure of the fluid is low, the floating speed is extremely high. However, in the actual operation of the gas compressor or the like, the supply pressure of the fluid is started at the atmospheric pressure. In many cases, the sealing surface 32 slides and deteriorates at a low speed equal to or lower than the floating rotation speed, and the reliability of the mechanical seal is reduced as described above.

Further, in the case where a low-speed aging operation on the driving device side is required in a steam turbine or the like, the operation is performed for a long time at the floating speed or lower, so that the sliding deterioration of the seal surface 32 also occurs in this case.

The present invention has been made in view of the above-mentioned problems of the prior art,
At low speed rotation, a larger flying height than the conventional technology is obtained to maintain the sealing performance of the shaft sealing part high, and even when the supply pressure of the fluid is low, there is no sliding deterioration of the sealing surface and reliability is improved. It is an object of the present invention to provide a mechanical seal device with high performance.

[0014]

According to the present invention, there is provided a rotating ring mounted on a rotating shaft, a movable ring mounted on a seal housing via a spring so as to be movable in an axial direction, and In a mechanical seal device configured to form a shaft sealing portion between a fixed ring pressed toward the rotating ring through the movable ring by a spring to seal between the high-pressure chamber and the low-pressure chamber, An annular groove is provided in the shaft sealing portion of the fixing ring, and a communication hole communicating the annular groove and the high-pressure chamber is provided in at least the fixing ring, and a shaft sealing portion of the rotating ring facing the annular groove is provided. Is characterized in that a plurality of spiral grooves for transferring the fluid in the annular groove are provided along the inner circumferential direction, and at least one circumferential groove is provided on the outer peripheral side of the spiral groove. To propose a mechanical seal device.

According to such a means, according to the mechanical seal of the present invention, the plurality of helical grooves provided in the shaft sealing portion of the rotating ring mounted on the rotating shaft can be moved from the communication hole into the annular groove of the fixed ring. The high pressure chamber and the low pressure chamber are sealed by transferring the fluid introduced into the chamber by rotation of the rotating ring. Fluid is introduced from the high pressure chamber into the annular groove through the communication hole of the fixing ring. Fluid from the annular groove is guided to the outward spiral groove, and dynamic pressure is generated in the spiral groove by rotation of the rotating ring. Further, the fluid flows from the outermost periphery of the spiral groove toward a circumferential groove provided on the outer peripheral side of the spiral groove, flows over a bank portion inside the circumferential groove, and flows into the circumferential groove. Here, the radial flow of the fluid is disturbed by the circumferential groove, and a high static pressure is generated. A floating force is generated by this static pressure, and the floating force allows the shaft sealing portion to float even at low speed rotation. The dynamic pressure generated in the spiral groove and the static pressure in the circumferential groove are combined to form a shaft sealing portion. Can be obtained.

Further, since the fluid flowing into the circumferential groove has a uniform static pressure over the entire circumference in the circumferential direction, the axial clearance of the shaft sealing portion is made uniform, and the rotating ring and the fixed ring are formed around the entire circumference in the circumferential direction. Thus, a good floating state can be obtained, and the shaft sealing portion can be uniformly levitated even at low speed rotation.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

FIG. 1 is a cross-sectional view of the upper half of the mechanical seal according to the embodiment of the present invention along the axis of rotation, FIG. 2 is an enlarged cross-sectional view of the shaft sealing portion, and FIG. FIG. 4 is a diagram showing the flying height of the shaft sealing portion.

1 to 3, reference numeral 5 denotes a rotating rotary shaft connected to a driving source (not shown) such as a motor, and reference numeral 8 denotes a casing of a rotary machine. An annular seal housing 9 is fitted in the fitting hole 8a of the casing 8 and its outer periphery 9a.
Is sealed in the casing 8 by being firmly inserted into the fitting hole 8a.

A rotary ring 1, a fixed ring 2, and a movable ring 22 are arranged inside the annular seal housing 9 in the axial direction. The rotary ring 1 is fixedly inserted into the outer periphery of the rotary shaft 5, and between the sleeve 6 whose shoulder front surface 6 a is pressed against the stepped surface 5 a of the rotary shaft 5 and the sleeve 7 fixedly inserted in the outer periphery of the sleeve 6. It is pinched and rotates with the rotating shaft 5.

The fixed ring 2 includes a spring 10 provided between the movable ring 22 and the seal housing 9.
(A plurality of them are provided in the circumferential direction) through the movable ring 22 to be pressed by the shaft sealing portion 3A with the rotating ring 1. The shaft sealing portion 3A seals a fluid chamber between a high-pressure chamber 3 in which a high-pressure fluid such as high-pressure gas and pressure oil is stored and a low-pressure chamber 4 such as the atmosphere.

In the axial direction of the fixed ring 2 and the movable ring 22, a plurality of communication holes 12 for connecting the shaft sealing portion 3A and the high-pressure chamber 3 are provided. An annular groove 2A is provided on the surface facing the ring 1,
The annular groove 2A is connected to the communication hole 12.

The high pressure chamber 3 and the low pressure chamber 4 are
A, in addition to an O-ring 25 between the movable ring 22 and the seal housing 9, an O-ring 26 between the movable ring 22 and the fixed ring 2, and the like, and a seal between the members fixed to each other. O-rings 21, 23, 2 for
4, 27 are fitted. The above basic configuration is the same as the mechanical seal according to the related art shown in FIGS.

In the embodiment of the present invention, the shaft sealing portion 3
A is configured by combining the spiral groove 31 and the circumferential groove 3B. That is, as shown in FIGS. 2 and 3, the shaft sealing portion 3A of the rotating ring 1 has a plurality of spiral grooves 31 and one or a plurality of circumferential grooves 3 provided on the outer peripheral side of the spiral groove 31.
B and a bank (flat surface) 3C are formed, so that the fluid in the annular groove 2A of the fixed ring 2 can be transferred to the high-pressure chamber 3 and the low-pressure chamber 4 by the rotation of the rotating ring 1 and sealed. I have.

During the operation of the rotary machine having the mechanical seal device having the above-described configuration, the plurality of spiral grooves 31 provided on the shaft sealing portion 3A of the rotary ring 1 are moved in the radial direction by the rotation of the fixed ring 1. By transferring
An axial bearing of the shaft sealing portion 3A is formed.

When the rotating shaft 5 is stationary and rotating, the sealing surface 3
2 is closed, but when it starts to rotate, the shaft sealing portion 3A slides due to the solid lubrication action, the levitation force starts to work at the lowest possible rotational speed, and the contact pressure between the sealing surfaces 32 is reduced. In addition, the sliding deterioration of the seal surface is reduced. During rotation, the fluid from the high pressure chamber 3 enters the annular groove 2A via the communication hole 12 of the movable ring 22 and the fixed ring 2. Then, the fluid from the annular groove 2 </ b> A is guided into the spiral groove 31, and a dynamic pressure is generated in the spiral groove 31 by the rotation of the rotating ring 1. Further, the fluid flows from the outermost periphery of the spiral groove 31 to the circumferential groove 3B provided on the outer peripheral side.
And gets over the bank 3C and flows into the circumferential groove 3B. Here, the radial flow of the inflowing liquid is disturbed by the circumferential groove 3B, and a high static pressure is generated. The floating force by the static pressure allows the shaft sealing portion 3A to float even at a low speed rotation. By combining the dynamic pressure in the groove 31 and the static pressure in the circumferential groove 3B, a predetermined floating amount of the shaft sealing portion 3A can be obtained.

Further, since the fluid flowing into the circumferential groove 3B has a uniform static pressure over the entire circumference in the circumferential direction, the axial clearance of the shaft seal portion 3A is made uniform, and The fixed ring 2 is in a state where there is no contact on the entire circumference in the circumferential direction, a good floating state is obtained, and the shaft sealing portion 3A can be floated even at low speed rotation. A plurality of circumferential grooves 3B and banks 3C can be provided to increase the floating force due to static pressure. However, the pressure loss due to the circumferential grooves 3B and the banks 3C increases from the inner circumference toward the outer circumference. Since the static pressure of the circumferential groove 3B becomes lower toward the outer peripheral side, the optimal number of the circumferential grooves 3B is selected.

As described above, in the embodiment of the present invention, the circumferential groove 3B is formed on the outer peripheral side of the spiral groove 31, and the high-pressure generated in the circumferential groove 3B causes the spiral groove 31 to float even at low rotation. Due to the combined floating force of the dynamic pressure generated in the spiral groove 31 and the static pressure generated in the circumferential groove 3B, even when the rotational peripheral speed V is small as shown by the solid line B in FIG. It is possible to obtain a larger flying height than that of the prior art shown by.

In the above-described embodiment, an example is shown in which the spiral groove 31 and the circumferential groove 3B are provided on the rotary ring 1 side, but separately from this, the spiral groove 31 and the circumferential groove 3 are provided on the fixed ring 2 side.
The same operation and effect can be obtained by providing B.

[0030]

As described above, according to the present invention, a spiral groove is provided in a shaft sealing portion of a rotating ring fixed to a rotating shaft, and at least one circumferential groove is provided on an outer peripheral side of the spiral groove. The floating force is generated by the high static pressure generated in the circumferential groove, and the floating amount is uniformed over the entire circumference in the circumferential direction, so that the shaft sealing portion floats at a lower rotation speed than the conventional technology. A predetermined floating amount of the shaft sealing portion can be obtained by a floating force obtained by combining the dynamic pressure generated in the spiral groove and the static pressure generated in the circumferential groove as described above.

Further, since the contact sliding of the seal surface in the shaft sealing portion is reduced, high sealing performance is maintained and the life of the mechanical seal is extended. Furthermore, even when the supply pressure of the fluid is low, the shaft sealing portion can be floated at low speed rotation. With the above, the sealing performance of the shaft sealing part is reliably maintained,
A highly reliable mechanical seal device can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an upper half of a mechanical seal according to an embodiment of the present invention along a rotation axis.

FIG. 2 is an enlarged sectional view of a shaft sealing portion in the embodiment.

FIG. 3 is a front view of a rotating ring in the embodiment.

FIG. 4 is a diagram illustrating a relationship between a floating amount of a shaft sealing portion and a rotating circumferential link;

FIG. 5 is a view corresponding to FIG. 1 showing a conventional mechanical seal device.

FIG. 6 is a front view of a rotating ring in a conventional mechanical seal device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating ring 2 Fixed ring 3 High pressure chamber 3A Shaft sealing part 3B Circumference part 3C Bank part 4 Low pressure chamber 5 Rotating shaft 6 Sleeve 7 Sleeve 8 Casing 9 Seal housing 10 Spring 12 Communication hole 31 Spiral groove

Claims (1)

[Claims] 1. A rotating ring mounted on a rotating shaft, a movable ring attached to a seal housing via a spring so as to be movable in an axial direction, and the spring moving toward the rotating ring via the movable ring. In a mechanical seal device configured to form a shaft sealing portion between the pressing ring and the sealing ring to seal between the high-pressure chamber and the low-pressure chamber, the shaft sealing portion of the fixing ring is provided with an annular groove. ,
A communication hole for communicating the annular groove and the high-pressure chamber is provided at least in the fixing ring, and a spiral groove for transferring fluid in the annular groove is provided in a shaft sealing portion of the rotating ring facing the annular groove. A mechanical seal device comprising a plurality of grooves provided along a circumferential direction, and at least one circumferential groove provided on an outer peripheral side of the spiral groove.