JPS6237573A - Shaft seal device - Google Patents

Abstract

PURPOSE:To eliminate the need of a sealed liquid pressure increasing device by providing spiral grooves extending from the vicinity of a boundary between sliding surfaces divided in the inside and outside diameter directions to the high pressure side where there is a sealed fluid on one of the inside and outside diameter sliding surfaces. CONSTITUTION:A plane sealing surface 11 of a rotary ring 1 fixed to a fixed shaft 3 and sealing surfaces 21a, 21b of static rings 2a, 2b divided in the directions of the inside and outside diameters are sliding surface which are adapted to slide through a liquid film. The sealing surface 21a comprises a spiral groove portion 9 where plane top portions 9a and spiral grooves 9b are alternately arranged, and a flat portion 10 which is positioned outside the spiral groove portion and on the same plane with the top portion 9a. The static ring 2a is provided with a supply hole 22 for connecting a space enclosing a spring 6 between the static rings 2a, 2b and a peripheral groove 19 disposed on the outer periphery of the static ring 2a, and the supply hole 22 is connected to a space L where there is a supply source for a sealed liquid by a supply hole 7 connecting the peripheral groove 19 and the space L.

Description

[Detailed Description of the Invention] [Objective of the Invention] "Industrial Application Field" The present invention is a shaft sealing device for a rotating shaft, in particular, an end face seal such as a mechanical seal, and a sealing device for sealing a rotary shaft such as a toxic or flammable gas or liquid. This invention relates to a shaft sealing device for fluid that must never leak.

``Prior Art'' An example of a conventional device of this kind is shown in Figure 1 in a vertical cross-sectional view. In the figure, a space H inside the casing is sealed with a high-pressure sealing fluid, and A is a space outside the casing where there is an atmosphere, and the sealing fluid in the space H flows out to the atmosphere side space A. The sealing surface of the rotating ring integrally or fixed to the rotating shaft 3 and the sealing surface 2 of the stationary ring slide in a state of fluid lubrication or boundary lubrication. There is.

The stationary ring is pushed in the axial direction by a spring 3 against the casing rod, but is locked to the casing rod by a rotation stopper (not shown) so that it does not rotate. In addition, a Q IJ ring is provided where the stationary ring slides into the casing and slides in the axial direction, separating the space H from the space. A floating ring seal 6 is attached to the end face of the cover/l which is sealed and fixed to the casing l and the air side space A is connected to the casing l and the floating ring seal 2.
It is pressed by a spring /3 arranged in the axial direction between the two.

A pressure fluid of p+Δp (Δp is several Kp/crR2) relative to the pressure p of the sealing fluid in the space H is supplied to the space through the supply hole 7, and the sealing surfaces of the rotating ring/ and the stationary ring// , 2/, due to the end face sealing effect, the pressure difference of Δp prevents the liquid in the space from leaking into the space H, and the sliding surface between the floating ring seal 2 and the rotating shaft 3 prevents the liquid in the space from leaking. leakage into the atmosphere side space A is suppressed.

``Problems to be Solved by the Invention'' This device requires: (1) When sealing high-pressure fluid, a special supply device is required to increase the pressure of the liquid to be sealed. ■It is necessary to always control the differential pressure between the sealing fluid and the liquid that confines it. ■Since it is a contact type seal, if the sealing conditions are strict, it will inevitably lack reliability and have a short lifespan. ■Space L LE is under high pressure, and when liquid leaks from the floating ring seal 26, it becomes atmospheric pressure, resulting in large losses. ■In order to seal the high-pressure fluid, a shaft sealing means is required to seal the liquid, which has a higher pressure than the high-pressure fluid, from the atmosphere side space, and because of the high pressure, a simple one may not be enough. In some cases, the axial length of the entire shaft sealing device must be made extremely long. I have such problems.

The present invention solves the above-mentioned problems in a shaft sealing device configured to seal a rotating shaft with an end face seal, and provides a shaft sealing device that is highly reliable, does not require a special pressure booster, and has a short axial length. The purpose is to provide equipment.

[Structure of the invention]

``Means for Solving the Problems'' The present invention provides that either a rotating ring or a stationary ring is divided in the inner and outer radial directions to form sliding surfaces of end faces in the inner and outer radial directions, and each of the divided rings in the inner and outer radial directions is The sliding surface of the rotary ring or the sliding surface of the end face of the undivided rotating ring or stationary ring are in pressure contact with each other by pressing means, and the divided portion of the rotating ring or stationary ring that is divided in the internal and external radial directions is The sliding surface is sealed so as to isolate it from the outside, and the sliding surface is divided into either the inner or outer radial direction. This is a shaft sealing device in which a spiral groove is provided so as to end in one direction, and a passage is provided on the stationary ring side to communicate the vicinity of the boundary with a low-pressure fluid supply source.

"Function" A low-pressure liquid is passed from a supply source through a passage containing a stationary ring to an annular gap that communicates the low-pressure side of a spiral groove near the boundary of the sliding surface of a rotating ring or a stationary ring that is divided in the radial direction. Low-pressure liquid is fed in, and when the rotating shaft rotates, the rotating ring rotates, and due to the effect of the spiral groove, the liquid on the low-pressure side moves to the high-pressure side where the spiral groove stops, increasing the pressure and generating dynamic pressure. This pressurized liquid seals the sealing fluid on the opposing flat surface of the sliding surface on the high pressure side. Shaft sealing with the atmosphere side is performed at the opposing flat portion of the sliding surface on the low pressure side that is pressed by a separate pressing means.

"Example" Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view. As in the conventional example shown in Fig. 5, a high-pressure sealed fluid is sealed in the space H in the casing, and A is the space on the outside of the casing on the atmosphere side. is supplied, but the pressure may be equal to or lower than the pressure of the sealing fluid in space H, and may be equal to atmospheric pressure.

A flat sealing surface of a rotating ring integrally or fixed to the rotating shaft 3, and a stationary ring core a divided in the inner and outer radial directions.
The sealing surfaces 2/& and -7b of 2b are sliding surfaces that slide through the liquid film. A spring guard is disposed in the axial direction between the stationary ring core a and the casing 1, and the spring guard allows the stationary ring 2 to
A is pushed in the axial direction toward the rotating ring l, or is locked to the casing plate with a rotation stopper (not shown), so that it does not rotate. In addition, the cylindrical part where the stationary ring 2a is slidably fitted to the casing ring is parallel to the QIJ ring.
is the provision.

The stationary ring b is slidably fitted to the stationary ring 2a at a cylindrical portion, and the ○ ring/J fitted into the circumferential groove of the stationary ring 2b at the sliding part creates a fit between the stationary ring 2a and b. Seal the joint and connect the rotating ring l and stationary ring 2a.
2b is isolated from the atmosphere side space A on the outside thereof.

The center hole of the stationary ring 2a has an enlarged diameter to form a circular hole 13, into which the enlarged diameter shaft portion 16 of the stationary ring λb is loosely fitted. Shoulder portion due to diameter expansion of stationary ring Ja, 2b/7. /l
The end turn portion of the compression spring 6 is in contact with. The spring 6 may be a helical spring centered around the rotating shaft 3, a disc spring, or a suitable number of helical springs arranged around the stationary ring 2b.

As shown in FIG. 2 in the front view, the sealing surface qa of the stationary ring 2a is located outside the spiral groove portion 9 in which the flat top portion 9a and the spiral groove 91 are arranged alternately and is flush with the top portion qa. Consists of flat part/Q. Each spiral groove 9
b penetrates through the center side. The stationary ring core a has a space containing a spring 6 between the stationary ring core a and J1+, and a QIJ ring j.

A supply hole here is provided which communicates with the circumferential groove /D provided on the outer periphery of the stationary ring core a between. It opens into a space with a source of liquid for use. The sealing surface 21b of the stationary ring 2b is a plane that can touch the sealing surface // of the rotating ring l.

The direction of rotation of the rotating shaft 3 is counterclockwise in FIG. 2, and a spiral groove is formed due to the pumping action. b involves the liquid from the open end on the center side, generates dynamic pressure toward the outer periphery, increases the pressure, and forms a spiral groove? Terminal part of b (outermost part)
In this case, a pressure slightly higher than that of the sealing fluid in space H is generated, and a liquid film is formed between the sealing surfaces ii, 2ta, and fluid lubrication occurs between the sealing surfaces ii, 2ta.

The maximum pressure of the liquid film of this fluid lubrication is determined by the fact that the sealing fluid in the space H does not enter, or the liquid on the space side is in a very small amount.
Allow it to leak to the side. This is particularly effective when the sealing fluid on the space H side is harmful, or even if it is not harmful in itself, it will cause serious problems if it leaks. The sealing effect between the sealing surfaces // and 21b is obtained when the stationary ring 2b, which is pressed by the pressure of the spring 6 and the sealed liquid, tries to come into pressure contact with the rotating ring /, similar to a normal end seal.

Load on sealing surface //, -/a W, spiral groove? b If the pressure at the end is pg, then the completely sealed surface //, 2/
When a fluid film is formed on FL, W=a pg...
It becomes... a is a coefficient determined by the shape of the spiral groove 9b, the number of grooves, the groove depth, etc. On the other hand, the pressing load W of the sealing surface //, ko/IL is the pressure p of the sealing fluid, the pressure po of the sealed liquid, Sl, s2 is the area of the pressing part, 81 = π
(r22-r12) However.

ko l"2 = outer diameter of sealing surface //, ko/a, ko rl = diameter of sliding part of stationary ring roller and casing hiro, 82-π
(r42-r52) However, 2r4=sealing surface //, λ/
Assuming that the outer diameter of 1), 2 rs = diameter of the stationary ring 2a and the sliding portion of cob, the load of the FT spring 3, and F2 is the load of the spring 6, W = 131p-8zpa + F1-72...
becomes @. from and @ apg=S, p E32
1) O+(I'+72), pa=0, and 81 is determined so that 51=a=k, then FT
−72=]((pg−p). Stationary ring 2
The differential pressure (pg-p) in the annular flat portion 10 of a will always be constant regardless of the sealing pressure p if the spring load (FT-F'2) is determined.

Further, the groove shape and groove depth of the spiral groove b are determined so that the thickness of the fluid film on the sealing surfaces // and 2/ is as thin as possible. Therefore, the sealing surface //.

27B, due to the pumping action of the spiral groove yb, Δp (several Kff/1ytt"
) is constantly raised to a high pressure to confine the sealing fluid and minimize the gap between the sealing surfaces /1, 1/eL to reduce leakage. Note that the value of Δp does not depend on the rotational speed, sealing pressure, or type of sealed liquid, but is determined only by the magnitude of the spring load of the spring 6.

From the supply hole 7, the circumferential groove/95 supply hole 22, the stationary ring,
Through the gap between 2a and 2b, the sealing surface //, j/a,
If the sealing fluid is a gas, choose oil, water, or another liquid to seal in the co/b; if the sealing fluid is a liquid, choose another safe clean liquid.

In particular, in the latter case, it is desirable to seal the liquid containing foreign matter with a clean liquid of the same kind. In addition, the sealed liquid sent from the space side leaking to the space H side where the sealed fluid is located can be easily separated if the sealed fluid in the space H is a gas, which is highly effective; It is very effective in cases where it is acceptable.

The liquid sealed from the space may be at atmospheric pressure,
It may be supplied by a low head pump or, if the pump uses this sealing device, the liquid itself may be introduced at low pressure on the suction side of the pump. Therefore, the pressure of the sealed liquid can be determined by the sealing ability between the sealing surfaces // and c/b that form the end seal portion. spiral groove 9
Although b was on the stationary ring 2a side, it may also be on the rotating ring side. In this embodiment, the depth of the spiral groove 9b is 3 to goμ.
m, and the liquid film thickness on the sliding surface is about 3 μm.

FIG. 3 is a longitudinal sectional view of another embodiment of the invention. While the flow in the spiral groove portion D in the previous embodiment is an outward flow, in the embodiment shown in FIG. 3, it is an inward flow.

A sealing fluid exists in the space H, a liquid for sealing the sealing fluid exists in the space, and the atmosphere exists in the space A.

A stationary ring 2b is slidably fitted into the cylindrical hole of the casing l, and the sliding surface is sealed by a ring g fitted into a circumferential groove provided on the cylindrical outer periphery of the stationary ring 21. The sealing surface 21b of the stationary ring b is pressed against the sealing surface // of the rotating ring / by a compression spring j inserted in the axial direction between the rotary ring b and the casing da.

A stationary ring 2a is slidably fitted into the inner cylindrical portion of the stationary ring b, and is sealed by a QIJ ring fitted into a groove provided in the circumferential direction on the cylindrical outer periphery of the stationary ring 2a. Waste λ on the corrugated shaft part and corrugated hole part of cob, cod tζ
A compression spring 6 is inserted so that these are still in contact with each other, and the stationary ring core a has its sealing surface Ko/a aligned with the sealing surface/l of the rotating ring L.
is being forced on. The sealed liquid is supplied from a supply hole in the space through a circumferential groove on the outer periphery of the stationary ring b that communicates with the supply hole 7. , passes through the supply hole J in the stationary ring xb through the circumferential groove /9 and the space housing the spring 6, and from the space housing the spring t through the gap 214 between the stationary rings 2a and 21, the stationary ring core a on the sliding surface. , 2b in the vicinity of the boundaries in the inner and outer radial directions.

Fig. 3 is a front view of the stationary ring. Stationary ring core a
A flat portion 10 disposed on the inner circumferential side of the rotary ring l slides on the end face of the rotary ring l to seal the sealing fluid in the space H. Each spiral groove? 1) The outer periphery side penetrates through, and the inner periphery side stops. Sealing surface u/1 of stationary ring, 21)
) is a plane that comes into close contact with the sealing surface l/ of the rotating ring /.

When the rotary shaft 3 rotates clockwise in FIG. Dynamic pressure is generated on the side. Due to this pressure, a pressure slightly higher than the pressure of the sealing fluid in the space H is created on the center side of the sealing surfaces 1/ and 2/a, and sealing is performed. The space between the sealed liquid and the atmosphere side space B is sealed by the sealing surface 1 of the stationary ring 2b, which is pressed by the spring and the pressure of the sealed liquid, and the sealing surface 1 of the rotating ring 1, similar to a normal end seal. .

In the fourth embodiment, the depth of the spiral groove 9b is set to 3 to 30 .mu.m, depending on the viscosity of the sealed liquid, so as to generate sufficient dynamic pressure and form a fluid film as thin as possible. The thickness of the liquid film between the sliding surfaces is approximately 3 μm.

The material of the rotating ring l and stationary ring 2a in each embodiment is that the side on which the spiral groove is provided is made of a hard material, especially ceramics (preferably silicon carbide SiO or silicon nitride 5isN4), and the mating sliding member is made of alumina ceramics or cemented carbide. , stainless steel, high lead bronze, ordinary cast iron, carbon, or the same material as the side on which the spiral groove 9b is provided are suitable. The sliding surfaces of the rotating ring/ and the stationary ring core a have a mirror finish, and the sliding is based on complete fluid friction due to the dynamic pressure effect of the spiral groove, so experiments have shown that the coefficient of friction is extremely low at 0.00 j, making it easy to cool. There's almost no need. In addition, the part provided with the spiral groove may be formed into a thin disk shape and bonded to the stationary ring λa or the rotating ring l, and if this mating member is also made of ceramics, it may be a plate as well. It may also be glued together.

In each of the embodiments, the stationary rings 2a, 2b are slid together with each other, but they may be slid on the stationary ring side, or the stationary rings 2a, 2b may be slid together with each other.
A, 21) remain as they are with the stationary rings 2a, 2b.
may be sealed together to the casing. The same applies to the method of arranging the resilient means such as springs, 6, etc.

In each of the embodiments, in order to press the sliding surface of the end seal, the stationary ring side is elastically pressed against the rotating ring, but the rotating ring side may be elastically pressed against the stationary ring.

That is, the present invention is capable of various modifications, and some examples are shown in FIGS. 3 to 7.

Figure 3 shows a case where the sealed liquid flows outward in the spiral groove part D, and the O-ring between the stationary ring cores a and 25 is replaced with the O-ring/2 between the stationary ring xb and the casing holder, and the stationary ring core b is pressed. The spring 6 is elastically repelled with respect to the casing da, and the stationary ring cores a and b
are in good agreement.

In the figure, the liquid enclosed in the spiral groove is flowing outward, and the stationary ring cores A and B are not in contact with each other. A stationary ring 2b is inserted through the inner cylindrical part of the stationary ring Ja, and the stationary ring 2b is slidably fitted with the cylindrical hole of the casing da, which is fitted with the stationary ring Ja, and sealed by the O-ring/co. It is pressed by a spring 6 which is elastically repelled based on da.

In the embodiments shown in FIGS. 3 and 6, the pressing force of the spring 6 that applies the pressing force of the stationary ring λb does not affect the stationary ring rollers, so the spring! , 6 can be determined independently.

The above is a case in which the flow on the sealing surface is directed outward, but the embodiment shown in FIG. 3 can be modified using the concepts shown in FIGS. 3 and 6.

In FIG. 7, the member on the rotating ring side is a double ring so that the sealing surface is divided into inner and outer parts. A rotary ring /b is slidably fitted to the rotary shaft 3, and is elastically repelled in the axial direction by a spring inserted between the rotary shaft 3 and the sealing surface llb of the stationary ring fixed to the casing. / and is prevented from rotating with respect to the one-rotation axis 3. The rotating ring /a is slidably fitted to the rotating ring /b, and is sealed with an O IJ song 2 provided between the rotating rings /a and /b, and its inner diameter is fixed by a spring j inserted between the rotating ring 3. A sealing surface //a provided with a spiral groove yb so as to stop at the outer circumferential side from the end is pressed against a flat sealing surface //a of the stationary ring.

The sealed liquid is supplied through the supply hole 7, the circumferential groove/9, and the supply hole to the vicinity of the boundary of the sliding surface, that is, the vicinity of the side appearing on the sealing surface of the sliding portion of the rotating rings ia and ib. In this embodiment, the rotating ring 1) is fixed to the rotating shaft 3, the stationary ring is slid onto the casing, and a spring 51 is provided between the casing and the stationary ring as shown by the chain double-dashed line. Good too.

〔Effect of the invention〕

In the present invention, either a rotating ring or a stationary ring is divided in the inner and outer radial directions to form sliding surfaces of end faces in the inner and outer radial directions, and the rotating ring or the undivided rotating ring or The sliding surfaces on the end faces of the stationary ring are in pressure contact with each other by pressing means, and the rotating ring divided in the inner and outer radial directions or the divided parts in the inner and outer radial directions of the stationary ring isolate the sliding surfaces from the outside. A spiral groove is provided on one of the sliding surfaces in the inner and outer radial directions, starting near the boundary of the sliding surface that is divided into the inner and outer radial directions and ending toward the high pressure side where the sealing fluid is present. Moreover, since the shaft sealing device is provided with a passage on the stationary ring side that communicates the vicinity of the boundary with the low-pressure fluid supply source, a special supply device for increasing the pressure of the sealed liquid is not required.

■ No device is required to control the pressure difference between the sealed liquid and the sealed fluid.

■ The sealing surface of the low-pressure liquid booster for sealing the sealed fluid is in a non-contact state, and the differential pressure between the sealing surface and the outside that seals the low-pressure liquid from the outside is extremely small, resulting in excellent reliability. Therefore, the lifespan can be extended.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a front view of the stationary ring of FIG. 1, and FIG. 3 is a longitudinal sectional view of another embodiment.
Figure 3 is a front view of the stationary ring in Figure 3, Figures 5 to 7.
Each figure is a longitudinal sectional view of another embodiment, and the first figure is a longitudinal sectional view of a conventional example. Me, /a, /b... Rotating ring C, Ko a, Co b... Stationary ring 3... Rotating axis Da... Casing j-, j'
, A...Spring 7...Supply hole j...Q IJ Songta...Spiral groove part 9a...Top part 9b...Spiral groove IO...Flat part //, //fL, //b--Sealing surface /2 --0 ring / da war - cover / 3rd reference - spring 16. Expanded diameter shaft part /7. /l...Shoulder /9...
Circumferential groove, 2/, 2/a, J/b # - Sealing surface 22.
23--Supply hole Column/Gap Colo... Floating ring Core, Cog... Shoulder A, H, L... Space. Patent applicant Ebara Research Institute, Ltd. Ebara Corporation

Claims (1)

[Claims] 1. Either a rotating ring or a stationary ring is divided in the inner and outer radial directions to form a sliding surface of the end face in the inner and outer radial directions, and the rotating ring or the stationary ring that is not divided into the respective sliding surfaces divided in the inner and outer radial directions The sliding surfaces on the end faces of the rings are in pressure contact with each other by pressing means, and the divided portions of the rotating ring or the stationary ring in the radially inner and outer directions isolate the sliding surfaces from the outside. A spiral groove is provided on one of the sliding surfaces in the inner and outer radial directions so as to start near the boundary of the sliding surface and end toward the high pressure side where the sealing fluid is present. The shaft sealing device further includes a passage on the stationary ring side that communicates the vicinity of the boundary with a low-pressure fluid supply source.