JPH11108197A - Shaft seal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a static friction force of a contact part other than a sealing sliding surface, improve abrasion resistance and ensure a following performance for a shaft vibration and a shaft displacement. SOLUTION: A DLC membrane 3 which is shown with many dots is adhered to a contact face on which a static friction force act such as a rubbing face between an end face of a seal ring 103 close to a face 101a in a radial direction of a seal case 101 and an end face of a cover ring 104, a rubbing face between both ends 103a in a circumferential direction of each segment 103A in the seal ring 103, and an outer peripheral face of the seal ring 103 and an inner peripheral face of the cover ring 104 which is slid on the outer peripheral face of the seal ring 103. Accordingly, the static friction force on the contact face is kept small, and good sealing sliding state between an inner peripheral face of the seal ring 103 and an outer peripheral face of a rotating shaft 2 can be kept while following a shaft vibration accompanied with a rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing device for sealing a fluid around a rotating shaft of an apparatus.

[0002]

2. Description of the Related Art High-speed mechanical seals have conventionally been used as gas generators and shaft sealing devices for various high-speed rotating devices. Their importance has been increasing with the progress of higher speed and smaller size. is there.

[0003] The mechanical seal has a rotating side sliding ring that rotates integrally with the rotating shaft, and a non-rotating sliding ring provided on a housing of a device surrounding the outer periphery of the rotating shaft. The shaft is sealed by sliding closely. Since rotating equipment such as general industrial machines to which a mechanical seal is actually attached has a certain radial vibration or axial displacement on the rotating shaft, sealing and sliding follow such radial vibration and axial displacement. It is necessary to keep the surface pressure and sliding state of the surface constant. Usually, a mechanical seal holds a constant pressing force by a spring or packing, and responds to radial vibration and axial displacement.

[0004] The portion between the stationary sliding ring and the housing, between the sliding ring and the end face of the spring, or a portion engaged by a detent pin for locking the sliding ring to the housing or the rotating shaft side, etc. Sliding also occurs in portions other than the sealing sliding surface, and the static friction force of these portions is larger than the dynamic friction force on the sealing sliding surface. For this reason, when the surface pressure of the sealing sliding surface fluctuates due to the fluctuation of the pressure of the fluid to be sealed, or when the rotating shaft is greatly displaced, the following operation of the sliding ring is delayed (malfunction) due to the static friction force. Arises
Leakage may occur due to opening between the sealing sliding surfaces on the rotating side and the stationary side, or conversely, the surface pressure may become excessive. Such a tendency becomes more remarkable as the rotation speed increases, and has a significant effect on the sealing performance.

[0005] In addition, when the micro-sliding is applied for a long period of time at a portion where the locking pin is engaged, the following performance is further deteriorated due to the formation of a step between the worn portion and the non-weared portion. become. As a method for improving the following performance of the sealing sliding surface, the following method has conventionally been adopted. (1) A lubricant is applied to a portion to which a static friction force is applied (hereinafter referred to as a contact portion). (2) The contact surface is roughened or grooved to reduce the substantial contact area, thereby reducing the apparent static friction force. (3) A sheet or ring made of a material having excellent lubricity is interposed in the contact area.

[0006]

However, the prior art described above
The following problems are pointed out in (1) to (4). Method (1) ······························································································································································ Can not expect. Method (2) ·················· Although effective at low load, frictional force may increase at high load. Method (3): Sheets made of a material with excellent lubricating properties often have poor abrasion resistance. To ensure long-term lubricating effects, the sheet needs to be thickened to some extent. A clearance that allows a thick sheet to intervene must be ensured.

The present invention has been made in view of the above circumstances, and a technical problem thereof is to reduce the static friction force at the contact portion other than the sealing sliding surface and to improve the wear resistance. By doing so, it is possible to ensure sufficient follow-up performance for shaft vibration and shaft displacement.

[0008]

As a means for effectively solving the above-mentioned technical problem, a shaft sealing device according to the present invention is composed of a plurality of members including a sealing sliding element, and these plurality of members are combined. Are provided with a DLC film on a contact surface that generates a static frictional force by contacting with a relative displacement. Here, “DLC” is an abbreviation for diamond-like carbon, and as will be described in detail later, intermediate properties (structure) between high-purity calcined carbon containing graphite (hereinafter, referred to as graphite carbon calcined body) and diamond ), Which are harder than carbon materials and the like used as ordinary sliding materials. Further, the DLC film has a function of filling fine irregularities existing on the surface of the base material and smoothing it. Therefore, the solid lubrication property and the wear resistance are excellent, and the static friction force between the members that come into contact with each other so as to be relatively displaceable can be reduced.

The "DLC" in the present invention is defined as follows by Raman spectrum analysis.

In measuring the Raman spectrum of a carbon-based sample, the surface of the sample is irradiated with an argon laser beam, and the spectrum of Raman scattered light from the sample surface is measured by a spectroscope. As shown in FIG. 5, in the Raman spectrum obtained by this, a sharp peak appears only in a graphite band (hereinafter, referred to as G band) around 1680 cm ^{−1 in} the case of single crystal graphite, and as a general seal sliding material. In the case of the graphite carbon fired body used, sharp peaks appear in both the G band and a diamond band around 1370 cm ^-1 (hereinafter referred to as D band). In the case of natural diamond, a sharp peak appears only in the D band.

[0011] In contrast, the hydrogen and the high content non-crystalline graphite film (a-CH coating), a hard coating (hard DLC film) comprising a diamond organization G band and 1370cm around ^-1 around 1680 cm ^-1 Of the D band, one or both of which are significantly broader than the spectral peaks of single crystal graphite, graphite carbon fired body or natural diamond, and the spectral intensity between both peaks is entirely It is getting bigger. The DLC referred to in the present invention includes all carbon-based materials having such a spectral pattern, and has a property (structure) intermediate between graphite carbon fired body and diamond. Relatively hard.

In the case where the shaft sealing device is, for example, a segment seal, the DLC film is formed on one or both of the contact surfaces of each segment and one of the contact surfaces of the segment and the seal case accommodating the segment. It is attached to both sides. For example, in the case of a mechanical seal, D
The LC film has a contact surface between the rotation side sliding ring and the rotating shaft side in the rotation preventing means, a contact surface between the stationary side sliding ring and the rotation preventing means between the housing side of the device, and the rotation side or the stationary side. The sliding ring is attached to a contact surface with a packing that supports the sliding ring on the rotation shaft side or the housing side so as to be movable in the axial direction.

[0013]

1 and 2 show a segment seal 100 as a first embodiment to which the present invention is applied, wherein 1 is an equipment housing and 2 is a rotary shaft. A cylindrical runner is mounted on the outer peripheral surface of the rotating shaft 2. The segment seal 100 is formed in a stepped shape in a circumferentially continuous annular receiving recess 102 formed in an inner peripheral portion of an annular seal case 101 closely fitted to an inner peripheral surface of the device housing 1. The seal ring 103 is composed of a plurality of segments 103A, which are arc-shaped carbon fired bodies that are annularly combined in a state where the circumferential ends 103a are rubbed slidably in the circumferential direction. It has a structure in which a cover ring 104 composed of a plurality of segments 104A, which is an arcuate graphite carbon fired body, is housed in a state of being bound in an annular shape by an extension spring 105 mounted on the outer periphery of the cover ring 104. Then, the inner peripheral surface 1 of the seal ring 103
03b is brought into close contact with the outer peripheral surface of the runner 2a, and one axial end face 103c of the seal case 101 faces the housing recess 102 by the axial urging force of the compression spring 107 backed up by the end plate 106. 101a, which shields the high pressure side space S _H and the low pressure side space S _L around the shaft.

Each segment 104 of the covering 104
A, a key 108 arranged at a predetermined position in the circumferential direction
The key 108 is provided with the seal ring 1
03 is engaged with a concave portion formed on the outer peripheral surface of each segment 103A. An engagement groove 108a formed through the key 108 in the radial direction is provided in the seal case 101.
The seal ring 103 is held in a non-rotating state by loosely engaging with the knock pin 109 which is driven into the radial surface 101a, and comes into sliding contact with the outer peripheral surface of the runner 2a. Further, since the engagement groove 108a of the key 108 which engages with the knock pin 109 has a shape extending in the radial direction,
The sealed sliding element assembly including the seal ring 103, the cover ring 104, the extension spring 105, and the key 108 can be displaced in the radial direction.

The inner peripheral surface 103 of the seal ring 103
b is gradually worn over a long period of use by being in sliding contact with the outer peripheral surface of the runner 2a, but the sealing sliding element assembly receiving the tightening force of the extension spring 105 Since the radial displacement is allowed as described above, the seal ring 103 is attached to the circumferential ends 1 of each of the segments 103A with the wear.
The gap G at 03a is reduced in diameter while being reduced. For this reason, the inner peripheral surface 103a of the seal ring 103 always keeps a close contact state with the outer peripheral surface of the runner 2a unless the wear progresses until the both ends 103a come into abutment with each other and the gap G disappears, Demonstrates the required sealing performance.

The end face 103c of the seal ring 103 and the end face 104a of the cover ring 104, which are in close contact with the radial face 101a of the seal case 101, the rubbing face between the circumferential ends 103a of each segment 103A of the seal ring 103, and the seal The outer peripheral surface of the ring 103 or the inner peripheral surface of the cover ring 104 rubbed against this is
Each of them is a "contact surface on which a static friction force acts" defined in the present invention. Therefore, these contact surfaces are shown in FIG.
A DLC film 3 is attached with a number of dots.
For this reason, the static frictional force of each of the contact surfaces is reduced, and when the rotating shaft 2 moves eccentrically relative to the seal case 101, the sealed sliding element assembly can favorably follow this. Always the inner peripheral surface 10 of the seal ring 103
The close contact between 3b and the outer peripheral surface of runner 2a is maintained.

As a method of applying the DLC film 3, for example, an ion beam evaporation method is used for a hard film containing a diamond structure, and for example, a plasma CVD (chemical vapor deposition) method is used for an a-CH film. However, the method is not particularly limited. It has been experimentally found that the thicker the DLC film 3 is, the longer the holding time of the film is. However, when the thickness exceeds 5 μm, the film tends to be easily worn. For this reason, the film thickness is set within 5 μm, preferably about 2 μm.

The DLC film 3 may be applied to both two surfaces (for example, the radial surface 101a of the seal case 101 and the end surface 103c of the seal ring 103 which is in close contact with the two surfaces). May be applied only to In this case, if one of the contact surfaces contains carbon or silicon, the adherence to the surface is higher, so in this embodiment, the seal ring 103 and the cover ring made of a carbon fired body are used. DLC on 104 side
The coating 3 is applied. In addition, when the surface to be adhered of DLC is made of a material not containing a large amount of carbon, it is difficult to obtain a large adhesion strength. Therefore, the DLC film 3 contains unbonded carbon or silicon particles and is bonded to the surface to be adhered. It is applied via an intermediate layer having good properties, typically an intermediate layer made of SiO ₂ or TiC. That is, when DLC is vapor-deposited on the intermediate layer, carbon of DLC bonds to unbonded carbon and silicon particles contained in the intermediate layer, and a film is formed with these carbon and silicon particles as nuclei. The silicon particles function as an anchor between the DLC film 3 and the intermediate layer, and can improve the adhesion strength with the base material.

FIG. 3 shows the results of a leak test performed on the segment seal 100 according to the above embodiment and a conventional segment seal. The test conditions were the following, which are generally not suitable for segment seals. The peripheral speed of the outer peripheral surface of the differential pressure · · · 8 kgf / cm ² runners 2a of the test conditions the high pressure side space S _H and the low-pressure side space S _L .......................・ 50m / s Fluid to be sealed ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Air temperature ・ ・ ・ ・ ・ ・ ・··········· 200 ° C Material of outer peripheral surface of runner 2a ······ Hard chrome coating

As is clear from the above test results, in the conventional segment seal, the amount of leakage increased rapidly immediately after the start of the test, whereas in the segment seal according to the embodiment, even after 100 hours from the start of the test, the leakage was large. No increase in leakage occurred. This is because even if the pressure difference between the high pressure side space S _H and the low pressure side space S _L is large, in the segment seal 100 of the embodiment, the seal case 101 and the seal ring 10
3 and the cover ring 104, the close contact surface between the seal ring 103 and the cover ring 104, and the static frictional force of the rubbing surface between the segments 103A of the seal ring are kept small by the DLC film 3.
This is because a good sealed sliding state between the inner peripheral surface 103b of the seal ring 103 and the outer peripheral surface of the runner 2a is maintained by favorably following the vibration of the rotating shaft 2.

FIG. 4 shows a mechanical seal 200 according to a second embodiment of the present invention. Reference numeral 1 denotes an equipment housing, and 2 denotes a rotating shaft. Mechanical seal 2
Reference numeral 00 denotes a stationary sliding ring 201 provided on the equipment housing 1 side and a rotating sliding ring 210 provided on the rotating shaft 2 and rotating so that the end faces substantially perpendicular to the axis slide close to each other. By doing so, it is possible to prevent the fluid in the sealed space S from leaking from the shaft circumference to the outside.

The stationary side sliding ring 201 is
3 and is closely fitted to the stationary-side retainer 202 through engagement with the knock pin 204.
02 is prevented from rotating relative to the stationary housing 202, and the stationary retainer 202 is axially movable via an operation packing 205 on a case 206 whose outer periphery is fixed to the device housing 1 via a pair of packings 207. Case 2
06, the rear surface is pressed by coil springs 208 arranged at predetermined intervals in the circumferential direction.
09, the relative rotation with the case 206 is prevented. That is, the stationary side sliding ring 201 is
The housing 1 is provided in a non-rotating state via the knock pin 204, the stationary side retainer 202, the drive pin 209, the case 206, and the like. It is pressed against the sliding ring 210.

On the other hand, the rotating side sliding ring 210 is tightly fitted to the rotating side retainer 211 via a packing 212 and is provided with a knock pin 213.
1, and the rotation side retainer 211 is
The packing 21 is attached to the collar 216 mounted on the outer peripheral surface of the rotating shaft 2 by the packing 217 and the set screw 218.
4 and the knock pin 215 prevents the relative rotation with the collar 216. That is, the rotation side sliding ring 210 is
3. The rotating force of the rotating shaft 2 is transmitted via the rotating side retainer 211, the knock pin 215, the collar 216, and the set screw 218, and the rotating shaft 2 is rotated in close contact with the stationary side sliding ring 201.

In the mechanical seal 200, packings 203, 205, 207,
Reference numerals 212, 214, and 217 have not only a sealing function between the members, but also a function of absorbing minute vibrations and keeping the sliding surface pressures of the stationary and rotating sliding rings 201 and 210 constant. 217, so that the contact surfaces of the packings 203... 217 have a low frictional force, and have excellent wear resistance so that the operability of the packings 203. Is desirable. Also, the engaging portions formed by the knock pins 204, 213, 215 and the drive pin 209 are portions where the static friction force acts. If the engaging portions are worn, the operability between the members is impaired, and the stationary side and the rotating side are reduced. Not only cannot the sliding surface pressure of the sliding rings 201 and 210 be kept constant, but also the knock pins 204 and 21
If 3,215 or the drive pin 209 itself wears, it may be broken by excessive torque. Therefore, in this embodiment, the contact surfaces with the packings 203... 217, the contact surfaces with the knock pins 204, 213, 215 and the drive pin 209, and the knock pins 20
4,213,215 and the surface of the drive pin 209,
A DLC film 3 is applied respectively.

When the DLC film 3 is applied, the target surface is wrapped or polished, and after cleaning, DLC is deposited by, for example, a plasma CVD method. Also, the knock pin 204 ...
The deposition of the DLC film 3 on the outer peripheral surface of the drive pin 209 and the inner peripheral surface of the hole engaging with these pins is performed while rotating these members.

The surface of the drive pin 209 has a DLC
A cycle test was performed on the mechanical seal on which the coating 3 was applied by a seal rotation tester under the following conditions. As a result, the surface of the drive pin 209 was sound without any wear. Test conditions Sealed space pressure ... 20 kgf / cm ^2- axis rotation speed ... 2,000 rpm Fluid to be sealed・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Room temperature Number of cycles ・ ・ ・ ・ ・ ・ ・ ・ ・ ・…… 2,000 times 1 cycle test time ……………………… 10 minutes

[0027]

According to the shaft sealing device of the present invention, the static frictional force of the contact surface where a plurality of members including the sealing sliding element come into contact with each other so as to be relatively displaceable is reduced by the application of the DLC film and the wear resistance is improved. Therefore, the sealing sliding surface smoothly follows the shaft vibration and the shaft displacement, and maintains a good sealing sliding state. For this reason, sealing performance can be improved.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a first embodiment in which the present invention is applied to a segment seal, cut along a plane passing through an axis.

FIG. 2 is a perspective view partially showing an assembly structure of the segment seal.

FIG. 3 is an explanatory diagram showing test results.

FIG. 4 is a sectional view showing a second embodiment in which the present invention is applied to a mechanical seal, cut along a plane passing through an axis.

FIG. 5 is an explanatory diagram showing a Raman spectrum pattern of a carbon-based material for defining DLC used in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Device housing 2 Rotating shaft 3 DLC film 100 Segment seal 101 Seal case 103A, 104A Segment (sealed sliding element) 200 Mechanical seal 201 Stationary side sliding ring (sealed sliding element) 203, 205, 207, 212, 214, 217 Packing 204, 213, 215 Dowel pin (detent pin) 209 Drive pin (detent pin) 210 Rotary side sliding ring (sealed sliding element)

Claims (3)

[Claims] A plurality of members including a sealing sliding element are combined, and a DLC film is applied to a contact surface which generates a static friction force when the plurality of members come into contact with each other so as to be relatively displaceable. Shaft sealing device. 2. The method according to claim 1, wherein the sealing sliding element comprises a plurality of segments which are annularly bound by an extension spring, and the contact surface on which the DLC film is applied is a contact between the segments. A shaft sealing device, which is one or both of one or both surfaces and a mutual contact surface between the segment and a seal case accommodating the segment. 3. The rotating sliding ring according to claim 1, wherein the sealing sliding element is fixed to a rotating sliding ring that is integrally rotated with the rotating shaft and to an equipment housing, and the rotating sliding ring is substantially aligned with the shaft center. The contact surface on which the DLC film is to be adhered is a contact surface of the rotation-side sliding ring and the rotation shaft side in a detent means, and the stationary surface is a stationary sliding ring which is slidably contacted by vertical end surfaces. The contact surface between the side sliding ring and the device housing side in the detent means and the contact surface between the rotating side or the stationary side sliding ring and the packing that supports the sliding ring so as to be axially movable on the rotating shaft side or the device housing side. A shaft sealing device characterized by a static friction force generating surface.