JPH057586B2 - - Google Patents

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 type is shown in FIG. 5, which is a longitudinal sectional view. In the figure, a space H inside the casing 4 is sealed with a high-pressure sealing fluid, and A is a space H inside the casing 4.
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 6 on the end face of the cover 14 which is sealed and fixed to the casing 4.
is the casing 4 and floating ring seal 6
They are pressed together by a spring 15 disposed in the axial direction between them.

p+△p for the pressure p of the sealing fluid in space H
(△p is several kg/cm ² ) pressurized liquid is supplied to the space L through the supply hole 7, and the end face sealing effect between the sealing surfaces 11 and 12 of the rotating ring 1 and the stationary ring 2 causes the above △ The pressure difference p prevents the liquid in the space L from leaking into the space H, and the sliding surface between the floating ring seal 6 and the rotating shaft 3 prevents the liquid in the space L from leaking into the atmospheric side space A. is suppressed.

``Problems to be Solved by the Invention'' When sealing high-pressure fluid, this device requires a special supply device to increase the pressure of the liquid containing it. 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 severe, it will inevitably lack reliability and have a short lifespan. The space L is under high pressure, and when liquid leaks from the seal 6, the pressure becomes atmospheric, resulting in a large loss. 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.
The purpose of the present invention is to provide a shaft sealing device that is highly reliable and does not require a special boosting device.

[Structure of the invention]

``Means for Solving the Problems'' The present invention is characterized in that the sliding surfaces of a rotating ring that rotates together with a rotating shaft and a stationary ring that is attached to a casing are pressed and slide, and the sliding surfaces seal the ring. In a shaft sealing device that performs This shaft sealing device is equipped with a passage that communicates the low-pressure side liquid with the space in which the low-pressure side liquid exists through a constriction part.

"Operation" When the rotating shaft rotates, the rotating ring rotates, and due to the effect of the spiral groove and the constriction part, the liquid on the low pressure side moves to the high pressure side where it stops, increasing the pressure and generating dynamic pressure. This pressurized liquid flows into the low-pressure side space through a passage that communicates with the high-pressure side terminal end of the spiral groove and the space where the low-pressure side liquid exists, and is circulated. As a result, the sealing fluid on the high pressure side is axially sealed by the liquid on the low pressure side whose pressure is increased at the terminal end of the spiral groove.

"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 example shown in FIG. 5, a space H inside the casing 4 is sealed with a high-pressure sealing fluid, and A is a space outside the casing 4 facing the atmosphere. Although the sealed liquid is supplied to 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. Further, the space L may only be filled with a sealing liquid.

The sealing surface 11 of the rotating ring 1, which is integrally or fixed to the rotating shaft 3, and the sealing surface 21 of the stationary ring 2 are sliding surfaces that slide through a liquid film. A spring 5 is disposed in the axial direction between the stationary ring 2 and the casing 4, and the stationary ring 2 is pushed in the axial direction toward the rotating ring 1 by the spring 5, but is not engaged with the casing 4 by a rotation prevention member (not shown). It is stopped so that it does not rotate. Further, an O-ring 8 is provided at the portion where the stationary ring 2 is slidably fitted to the casing 4 to separate the space H and the space L. The space L and the atmosphere side space A are arranged in the axial direction between the casing 4 and the floating ring seal 6 on the end face of the cover 14, which is sealed and fixed to the casing 4, with the floating ring seal 6 slidingly fitted on the rotating shaft 3. It is sealed and shut off by being pressed by a spring 15.

As shown in FIG. 2 in the front view, the sealing surface 21 of the stationary ring 2 is formed from a spiral groove portion 9 in which a flat top portion 9a and a spiral groove 9b are arranged alternately, and a flat portion 10 located on the outside thereof and coplanar with the top portion 9a. Become. The center side of the spiral groove 9b penetrates through,
The outer circumference side is designed to stop.

The annular groove 13 provided to communicate the terminal end of the spiral groove 9b and the low-pressure side space L are communicated through a communication hole 17 with a constriction part 16 machined in the stationary ring 2, and the enclosed liquid pressurized in the spiral groove 9b is kept under low pressure. It flows to the side and performs a cooling effect on the sealing surfaces 11 and 12.
The size of the constricted portion 16 is appropriately selected depending on the degree of pressure increase and cooling.

Reference numeral 7 denotes a supply hole for a liquid used for sealing into a space L provided in the casing 4, and the space L is filled with a low-pressure liquid.

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 increases 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 21. A liquid film is formed, and fluid lubrication is provided between both sealing surfaces 11 and 21. The pressure of this fluid lubrication liquid film is such that the sealing fluid in the space H does not enter, or the liquid in the space L side leaks a small amount to the space H side. By doing this,
This is particularly effective when the sealing fluid on the space H side is harmful, or even if it is not harmful itself, it will cause serious problems if it leaks. The sealed liquid that enters the annular groove 13 from the end of the spiral groove 9b flows through the constriction part 16 to the space L through the communication hole 17 and circulates between the rotating shaft 3 and the stationary ring 2 in the axial direction. Note that when the rotating shaft 3 is stopped, the stationary ring 2 is connected to the rotating ring 1.
The flat part of the sealing surface closes the sealing fluid in the space H.

The degree of pressure increase of the sealed liquid in the space L by the spiral grooves 9b of the sealing surfaces 11 and 21 is determined by the pressure of the sealing fluid in the space H and the sealing surface 1 by the pressure of the sealing fluid in the space H and other pressing means (for example, the spring 5).
It is determined by selecting the pressing load in 1 and 21. Here, the pressing load due to the pressure of the sealing fluid in space H is the pressing part area s = π (r ² ₂ − ^{r 2} ₁ ): However, 2r ₂ is the sealing surface 11, 2
The outer diameter of 1, 2r _1, is determined by the diameter of the sliding portion of the stationary ring 2 and the casing 4.

Further, as the liquid to be sealed in the space L, if the sealing fluid is a gas, select oil, water, or another liquid, and if the sealing fluid is a liquid, select 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. Furthermore, the sealed liquid in the space L that leaks to the side of the space H where the sealing fluid is located can be easily separated when the sealing fluid in the space H is a gas, which is highly effective.
In the case of a liquid, it is most effective when a small amount of it can be mixed in.

The liquid sealed in the space L may be at body 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. Furthermore, since this liquid is under low pressure, leakage can be limited as much as possible with a simple seal such as the floating ring seal 6. The seal on the atmospheric pressure side may, of course, be a mechanical seal or other seal, and is selected depending on the situation. Although the spiral groove 9b was placed on the stationary ring 2 side, it may also be placed on the rotating ring side. In this case, the annular groove 13 may be placed on the rotating ring 1 side or on the stationary ring 2 side.

FIG. 3 is a longitudinal sectional view of another embodiment of the invention. While the flow in the spiral groove 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 attachment relationship of the stationary ring 2 to the casing 4 and the relationship of the rotating ring 1 to the rotating shaft 3 are the same as in the previous embodiment. The space L is configured on the rotating ring side, and the floating ring seal 6 is pressed against the cover 14 that is sealed and fixed to the member ⁴¹ that is sealed and fixed to the casing 4, and the space between the floating ring seal 6 and the rotating shaft 3 is It is a rotating seal.

FIG. 4 is a front view of the stationary ring 2. The spiral grooves 9b provided in the stationary ring 2 penetrate to the outer periphery, have a dead end on the center side, each spiral groove 9b is connected by an annular groove 13, and there is a flat portion 10 on the center side from the annular groove 13. . The annular groove 13 is a constricted portion 16 provided in the axial direction of the rotating ring 1.
It communicates with the space L through a communication hole 17 attached thereto.

When the rotating shaft 3 rotates clockwise in FIG. 4, the liquid in the space L is drawn into the spiral groove 9b,
Dynamic pressure is generated on the center side, and at the terminal end (innermost circumference) of the spiral groove 9b, the pressure is slightly higher than the pressure of the sealing fluid in the space H, and sealing is performed. The liquid that has entered the annular groove 13 from the spiral groove 9b flows through the constriction portion 16 to the space L through the communication hole 17 and is circulated.

In this embodiment as well, the spiral groove 9b and the annular groove 13 may be provided on either side of the rotating ring 1 or the stationary ring 2. In the second embodiment, the depth of the spiral groove 9b is set to, for example, 3 to 50 μm, depending on the viscosity of the sealed liquid, so as to generate sufficient dynamic pressure and form a fluid film as thin as possible.

Rotating ring 1 and stationary ring 2 in each embodiment
The material on which the spiral groove is provided is a hard material, especially ceramics (silicon carbide Si or silicon nitride Si ₃₎ .
(N ₄ is preferred) 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 2 have a mirror finish, and the sliding is completely based on fluid friction due to the dynamic pressure effect of the spiral groove, so the coefficient of friction is 0.003 according to experiments, which is extremely low and requires cooling. There are almost no Therefore, in addition to the cooling effect of the circulating low-pressure side liquid for shaft sealing, temperature rise is completely prevented.
In addition, in the part provided with the spiral groove, the member provided with the spiral groove in the above may be in the form of a disc of grooved material and may be adhered to the stationary ring 2 or the rotating ring 1.
If this mating member is also made of ceramics, it may be similarly made into a plate shape and bonded.

[Effects of the Invention] The present invention provides a shaft sealing device in which a rotating ring that rotates together with a rotating shaft and a stationary ring that is attached to a casing side are pressed against each other so that the sliding surfaces thereof slide, and the sliding surfaces provide a seal. In this method, a spiral groove is provided on one of the sliding surfaces so that the liquid on the low pressure side is drawn in toward the high pressure side by the rotation of the rotary ring so as to end on the high pressure side, and the end of the spiral groove on the high pressure side is connected to the liquid on the low pressure side. Since the shaft sealing device is equipped with a passage communicating with the existing space, there is no need for a special supply device to increase the pressure of the sealed liquid.

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

Since the sealing surface is non-contact, it is highly reliable and has a long life.

Leakage of the sealed liquid to the outside is extremely small, and losses are also small.

The cooling effect of the sealing surface can be increased.

The effects of

[Brief explanation of the drawing]

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, and FIG. 5 is a longitudinal sectional view of a conventional example. 1... Rotating ring, 2... Stationary ring, 3...
Rotating shaft, 4... Casing, 4 ₁ ... Member, 5...
...Spring, 6...Floating ring seal, 7
... Supply hole, 8 ... O-ring, 9 ... Spiral groove, 9a ... Top, 9b ... Spiral groove, 1
0... Flat part, 11, 21... Sealing surface, 13
...Annular groove, 14...Cover, 15...Spring, 1
6...Aperture part, 17...Communication hole..., A, H, L
……space.

Claims (1)

[Claims] 1. In a shaft sealing device in which the sliding surfaces of a rotating ring that rotates with the rotating shaft and a stationary ring attached to the casing side are pressed and slide, and the sliding surfaces create a seal, either sliding A spiral groove is provided on the surface so that the liquid on the low-pressure side is drawn in toward the high-pressure side by the rotation of the rotating ring so as to end on the high-pressure side, and the end of the spiral groove on the high-pressure side is connected to the space where the liquid on the low-pressure side exists through a constriction part. A shaft sealing device equipped with a passage that communicates with the shaft.