JPH0219351B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] "Industrial Application Field" The present invention relates to a shaft sealing device for a rotating shaft, especially an end face seal such as a mechanical seal, and a sealing device for sealing a rotary shaft such as a gas or liquid that is toxic or flammable. The present invention relates to a shaft sealing device for fluid that is absolutely prohibited from leaking.

"Prior Art" An example of a conventional device of this kind is shown in FIG. 8, which is a longitudinal sectional view. In the figure, a space H inside the casing 4 is sealed with high-pressure sealing fluid, and A is a space H inside the casing 4.
It is a space with an atmosphere on the outside side of 11 and the sealing surface 21 of the stationary ring 2 are adapted to slide under fluid lubrication or boundary lubrication.

The stationary ring 2 is pushed in the axial direction against the casing 4 by a spring 5, but is locked to the casing 4 by a rotation preventing member (not shown) so that it does not rotate. Further, an O-ring 8 is provided where the stationary ring 2 slides on the casing 4 and slides in the axial direction, and separates the space H and the space L. space L
and the atmosphere side space A has a floating ring seal 2 on the end face of the cover 14 which is sealed and fixed to the casing 4.
6 is pressed against the casing 4 and the floating ring seal 26 by a spring 15 disposed in the axial direction.

p+△p for the pressure p of the sealing fluid in space H
Pressure fluid (Δp is several kg/cm ² ) is supplied to the space L through the supply hole 7, and the sealing effect between the sealing surfaces 11 and 21 of the rotating ring 1 and the stationary ring 2 is due to the above-mentioned Δp. The pressure difference prevents the liquid in the space L from leaking into the space H, and the sliding surface between the floating ring seal 26 and the rotating shaft 3 prevents the liquid in the space L from leaking into the atmospheric side space A. I'm suppressing it.

``Problems to be Solved by the Invention'' When sealing a high-pressure fluid, this device requires a special supply device to increase the pressure of the liquid enclosing the high-pressure fluid. It is necessary to constantly 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 severe, it will inevitably lack reliability and have a short lifespan. Space L is under high pressure and floating ring seal 2
6, the liquid leaks and becomes atmospheric pressure, resulting in a large loss. To seal high pressure fluid,
A shaft sealing means is required to seal the high-pressure liquid that confines it from the atmosphere side space, and because of the high pressure, a simple one may not be enough. In some cases, the length in the direction must be made extremely large. I have the same problem.

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

[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.

"Operation" A low-pressure liquid is passed from a source of liquid 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 inner and outer radial directions. 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" Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view. As in the conventional row shown in FIG. 8, a space H inside the casing is sealed with a high-pressure sealing fluid, and A is a space on the outside of the casing 4 facing the atmosphere. Although the sealed liquid is supplied from the supply device provided in the space L, the pressure may be equal to or lower than the pressure of the sealed fluid in the space H, and may be equal to atmospheric pressure.

The flat sealing surface 11 of the rotating ring 1, which is integrally or fixed to the rotating shaft 3, and the sealing surfaces 21a, 21b of the stationary rings 2a, 2b, which are divided in the inner and outer radial directions, are sliding surfaces that slide through a liquid film. It's summery. A spring 5 is arranged in the axial direction between the stationary ring 2a and the casing 4, and the stationary ring 2a is pushed in the axial direction toward the rotating ring 1 by the spring 5, but the casing 4
It is locked by a rotation prevention member (not shown) to prevent it from rotating. Further, an O-ring 8 is provided in parallel to the cylindrical portion where the stationary ring 2a is slidably fitted to the casing 4.

The stationary ring 2a is slidably fitted to the stationary ring 2a at a cylindrical portion, and an O-ring 12 fitted into a circumferential groove of the stationary ring 2b at the sliding portion closes the fitting portion between the stationary rings 2a and 2b. The sliding surface between the rotating ring 1 and the stationary rings 2a and 2b is sealed off from the atmosphere side space A on the outside thereof.

The center hole of the stationary ring 2a is enlarged in diameter to form a circular hole 13, into which the enlarged diameter shaft portion 16 of the stationary ring 2b is loosely fitted. The end turn portion of the compression spring 6 is in contact with the shoulder portions 17, 18 due to the enlarged diameter of the stationary rings 2a, 2b. 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.

The sealing surface 21a of the stationary ring 2a is the second
As shown in the figure, the flat top 9a and the spiral groove 9
It consists of a spiral groove part 9 in which grooves b are arranged alternately and a flat part 10 located on the outside thereof and on the same plane as the top part 9a. Each spiral groove 9b penetrates through the center side. The stationary ring 2a is provided with a supply hole 22 that communicates between the space containing the spring 6 between the stationary rings 2a and 2b and the circumferential groove 19 provided on the outer periphery of the stationary ring 2a between the O-rings 8 and 8. Through the supply hole 7 which communicates with the circumferential groove 19 and the space L, the supply hole 22 communicates with the space L where there is a supply source of an encapsulating liquid (not shown). The sealing surface 21b of the stationary ring 2b is a plane that can be in contact with the sealing surface 11 of the rotating ring 1.

The rotating direction of the rotating shaft 3 is counterclockwise in FIG. 2, and the pumping action causes the spiral groove 9b to draw in liquid from the open end on the center side.
Dynamic pressure is generated and increased toward the outer periphery, and a pressure slightly higher than the pressure of the sealing fluid in the space H is generated at the terminal end (outermost periphery) of the spiral groove 9b, and a pressure is generated between the sealing surfaces 11 and 21a. A liquid film is formed, and fluid lubrication is provided between both sealing surfaces 11 and 21a. The maximum pressure of this fluid lubrication liquid film is set such that the sealing fluid in the space H does not enter, or the liquid in the space L side leaks a minute amount to the space H 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. Sealing surface 11, 21
The sealing action between b and 1 is obtained when the stationary ring 2b, which is pressed by the pressure of the spring 6 and the sealed liquid, attempts to come into pressure contact with the rotating ring 1, similar to a normal end seal.

If the load on the sealing surfaces 11 and 21a is W, and the pressure at the end of the spiral groove 9b is p _g , then the sealing surface 1 is completely
When a fluid film is formed at 1 and 21a, W=ap _g . . . . 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 on the sealing surfaces 11 and 21a is the pressure p of the sealing fluid, the pressure po of the sealed liquid, s ₁ and s ₂ are the areas of the pressing part, and S ₁ = π (r ₂ ² − r ₁ ² ), where 2r ₂ = 11 of the sealing surface,
Outer diameter of 21a, 2r ₁ = Diameter of the sliding portion of stationary ring 2a and casing 4, S ₂ = π(r ₄ ² − r ₃ ² ) However,
2r ₄ = outer diameter of sealing surfaces 11, 21b, 2r ₃ = diameter of sliding portion of stationary rings 2a, 2b, F ₁ is load of spring 5, F ₂ is load of spring 6, W = S ₁ p −S ₂ p ₀ +F ₁ −F ₂ ………. and from ap _g = S ₁ p−S ₂ p ₀ + (F ₁ −
F ₂ ), and if S ₁ is determined so that P ₀ =0 and S ₁ =a=k, then F ₁ −F ₂ =k(p _g −p). The differential pressure (p _g -p) at the annular flat portion 10 of the stationary ring 2a will always be constant regardless of the sealing pressure p if the spring load (F ₁ -F ₂ ) is determined.

In addition, the groove shape of the spiral groove 9b is adjusted so that the thickness of the fluid film on the sealing surfaces 11 and 21 is as thin as possible.
The groove depth shall be determined. Therefore, the sealing surface 11,
21a, due to the pumping action of the spiral groove 9b, △p (several Kgf/cm ² ) with respect to the pressure p of the sealing fluid.
The pressure is constantly increased to a high level to confine the sealing fluid, and the gap between the sealing surfaces 11 and 21a is minimized 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 loads of the springs 5 and 6.

From the supply hole 7 to the sealing surface 1 via the circumferential groove 19, the supply hole 22, and the gap 24 between the stationary rings 2a and 2b.
The liquid to be sealed in the sealing fluids 1, 21a, and 21b is selected from oil, water, or other liquid when the sealing fluid is a gas, and when the sealing fluid is a liquid, another safe clean liquid is selected. In particular, in the latter case, it is desirable to seal the liquid containing foreign matter with a clean liquid of the same kind. Also, the space H where there is a sealing fluid
The sealed liquid sent from the side of the space L that has leaked to the side can be easily separated if the sealed fluid in the space H is a gas, and is highly effective.If the sealed fluid is a liquid, it is effective when a small amount of liquid is allowed to be mixed in. It's large.

The liquid to be sealed from the space L may be at atmospheric pressure, and may be supplied by a low head pump, or if this sealing device is used for the pump, the liquid itself at low pressure on the suction side of the pump may be introduced. It's okay. Therefore, the sealing surface 1 which becomes the end face seal portion
The pressure of the sealed liquid can be determined by the sealing ability between 1 and 21b. Although the spiral groove 9b was placed on the stationary ring 2a side, it may be placed on the rotating ring side. In this embodiment, the depth of the spiral groove 9b is 3
~50μm, and the liquid film thickness on the sliding surface is 1~3μm.
It is about m.

FIG. 3 is a longitudinal sectional view of another embodiment of the invention. While the flow in the spiral groove portion 9 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 L, and the atmosphere exists in the space A.

The stationary ring 2b is slidably fitted into the cylindrical hole of the casing 4, and the sliding surface is sealed by an O-ring 8 fitted into a circumferential groove provided on the cylindrical outer periphery of the stationary ring 2b. By means of a compression spring 5 inserted axially between the casings 4, the stationary ring 2b is pressed with its sealing surface 21b against the sealing surface 11 of the rotating ring 1.

The stationary ring 2a is attached to the inner cylindrical part of the stationary ring 2b.
are slid together and sealed by an O-ring 12 fitted into a groove provided in the circumferential direction on the cylindrical outer periphery of the stationary ring 2a, and shoulders 27, 28 of the stepped shaft portion and stepped hole portion of the stationary rings 2a, 2b. Compression springs 6 are inserted so as to abut on each of them, and the sealing surface 21a of the stationary ring 2a is pressed against the sealing surface 11 of the rotating ring 1. The sealed liquid is supplied from a supply source in the space L to the supply hole 7, a circumferential groove 19 on the outer periphery of the stationary ring 2b that communicates with the supply hole 7, and a supply hole in the stationary ring 2b that communicates with the circumferential groove 19 and the space housing the spring 6. 23, and from the space where the spring 6 is housed, the stationary rings 2a, 2
It communicates with the vicinity of the boundary between the stationary rings 2a and 2b in the radial direction of the inside and outside on the sliding surface through the gap 24 between b.

FIG. 4 is a front view of the stationary ring 2. A flat portion 10 disposed on the inner circumferential side of the stationary ring 2a slides on the end face of the rotating ring 1 to seal the sealing fluid in the space H. The outer circumferential side of each spiral groove 9b penetrates through, and the inner circumferential side has a dead end. The sealing surface 21b of the stationary ring 2b is a flat surface that closely contacts the sealing surface 11 of the rotating ring 1.

When the rotary shaft 3 rotates clockwise in FIG. 4, the sealed liquid that is being sent from the space L to the vicinity of the boundary between the inner and outer diameters of the sliding surfaces of the stationary rings 2a and 2b is caught in the spiral groove 9b, and is drawn toward the center side. Dynamic pressure is generated. This pressure creates a pressure slightly higher than the pressure of the sealing fluid in the space H on the center side of the sealing surfaces 11 and 21a, and sealing is performed. Between the sealed liquid and the atmosphere side space L, there is a spring 5 and a stationary ring 2b which is pressed by the pressure of the sealed liquid, similar to a normal end seal.
The sealing surface 21b of the rotary ring 1 and the sealing surface 11 of the rotary ring 1 provide a seal.

In the second embodiment, the depth of the spiral groove 9b varies depending on, for example, the viscosity of the sealed liquid so as to generate sufficient dynamic pressure and form a fluid film as thin as possible.
The size should be ~50 μm. The thickness of the liquid film between the sliding surfaces is about 1 to 3 μm.

Rotating ring 1 and stationary ring 2 in each embodiment
The material of a is a hard material on the side where the spiral groove is provided,
Especially ceramics (silicon carbide SIC or silicon nitride)
Si ₃ N ₄ is preferable) and the mating sliding member is alumina ceramics, cemented carbide, stainless steel, high lead bronze, ordinary cast iron, carbon, or spiral groove 9
It is preferable to use the same material as the material on which b is provided. The sliding surfaces of the rotating ring 1 and the stationary ring 2a have a mirror finish, and the sliding is based on complete fluid friction due to the dynamic pressure effect of the spiral groove, so the coefficient of friction is as low as 0.003 according to experiments, and cooling is not necessary. There are almost no In addition, the part provided with the spiral groove may be formed into a thin disk shape and adhered to the stationary ring 2a or the rotating ring 1, and if this mating member is also made of ceramics, it may be made of a plate as well. It may also be glued together.

In each of the embodiments, the stationary rings 2a, 2b are slidably fitted to each other, but they may be slidably fitted to the casing 4, respectively.Also, the stationary rings 2a, 2b may be slidably fitted to the casing 4, while the stationary rings 2a, 2b are slidably fitted to each other. It may also be sealed against. The same applies to the method of arranging the resilient means such as the springs 5 and 6.

In each embodiment, 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. 5 to 7.

In FIG. 5, when the sealed liquid flows outward in the spiral groove 9, the O-ring between the stationary rings 2a and 2b is replaced with the O-ring 12 between the stationary ring 2b and the casing 4, and a spring 6 that presses the stationary ring 2b is used. The stationary rings 2a and 2b are adapted to be elastically resilient with respect to the casing 4, and the stationary rings 2a and 2b are slidably fitted together.

In FIG. 6, the sealed liquid in the spiral groove 9 flows outward, and the stationary rings 2a and 2b are not in contact with each other. A stationary ring 2b is inserted through the inner cylindrical part of the stationary ring 2a, and the stationary ring 2b is slidably fitted with the cylindrical hole of the casing 4 to which the stationary ring 2a is fitted and sealed by the O-ring 12, and the casing 4 is sealed. It is pressed by a spring 6 that springs against the reference.

In the embodiments shown in FIGS. 5 and 6, the pressing force of the spring 6 that applies the pressing force of the stationary ring 2b is the same as that of the stationary ring 2a.
The springs 5 and 6 can each have their requirements 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. 5 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.
The rotating ring 1b is slidably fitted to the rotating shaft 3, and the rotating shaft 3
The spring 6 inserted between the casing 4 and the casing 4 is elastically resilient in the axial direction, and its sealing surface 11b is pressed against the sealing surface 21 of the stationary ring 2 fixed to the casing 4, so that it does not rotate with respect to the rotating shaft 3. It's stopped. The rotating ring 1a is slidably fitted onto the rotating ring 1b, and is sealed with an O-ring 12 provided between the rotating rings 1a and 1b. A sealing surface 11 provided with a spiral groove 9b so as to stop the flow.
a is pressed against the flat sealing surface 21 of the stationary ring 2.

The sealed liquid passes through the supply hole 7, the circumferential groove 19, and the supply hole 7, and reaches the vicinity of the boundary of the sliding surface, that is, the rotating ring 1a,
It is supplied near the side that appears on the sealing surface of the sliding portion of 1b. In this embodiment, the rotating ring 1b is fixed to the rotating shaft 3, the stationary ring 2 is slid onto the casing 4, and a spring 5' is provided between the casing 4 and the stationary ring 2 as shown by the chain double-dashed line. It's okay.

〔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. In addition, 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.

A device for controlling the pressure difference between the sealed liquid and the sealed fluid is not required.The sealing surface of the low-pressure liquid pressurizing section for sealing the sealed fluid is in a non-contact state and is sealed against the outside of the low-pressure liquid. The differential pressure between the surface and the outside is extremely small, resulting in excellent reliability and a long service life.

[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, FIG. 3 is a longitudinal sectional view of another embodiment, and FIG. 4 is a stationary ring of FIG. 3. A front view of the ring, FIGS. 5 to 7 are longitudinal cross-sectional views of still other embodiments, and FIG. 8 is a vertical cross-sectional view of a conventional example. 1, 1a, 1b...rotating ring, 2, 2a, 2
b... Stationary ring, 3... Rotating shaft, 4... Casing, 5, 5', 6... Spring, 7... Supply hole, 8
...O-ring, 9...Spiral groove, 9a...
Top part, 9b...Spiral groove, 10...Flat part, 11, 11a, 11b...Sealing surface, 12...
O-ring, 14...Cover, 15...Spring, 16
...Expanded diameter shaft portion, 17, 18...Shoulder portion, 19...Circumferential groove, 21, 21a, 21b...Sealing surface, 22,
23... Supply hole, 24... Between, 26... Floating ring, 27, 28... Shoulder, A, H, L
……space.

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 is not divided into the respective sliding surfaces divided in the inner and outer radial directions. are in pressure contact with the sliding surfaces of the end faces of the rings by means of pressing means, and the dividing portions of the rotating ring or the stationary ring in the radially inner and outer directions are designed to block the sliding surfaces from the outside. A spiral groove is provided on one of the sealed 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, and A shaft sealing device provided with a passage on the stationary ring side that communicates the vicinity of the boundary with a low-pressure fluid supply source.