JPH04296259A - Noncontact sealing device - Google Patents

Abstract

PURPOSE:To maintain smoothness on a static side sealing end and parallelism with a turning side sealing end to the former by preventing both heat and pressure strains in the static side sealing end from exceeding the proper limit. CONSTITUTION:This sealing device is constituted so as to form a sealing part S by means of a fluid film in a seal case 1 in an interval between a turning seal ring 3, clamped to a turning shaft 2, and a static seal ring 4 energized to be pressed to the turning seal ring 3 by dint of a spring 6 via a holding ring 5. According to this method, an interval between both these rings 4 and 5 is kept in a noncontact state that is sealed by interposing an O-ring 10 between them in the axial direction.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a non-contact sealing device suitable for use in rotating equipment that mainly handles gas (nitrogen, argon, hydrogen, natural gas, air, etc.), such as turbines, blowers, and centrifugal compressors. Specifically, fluid is generated between a rotating sealing ring fixed to a rotating shaft and a stationary sealing ring that is biased toward the rotating sealing ring via a retaining ring by a spring in the seal case. The present invention relates to a non-contact sealing device configured to form a membrane seal.

0002

2. Description of the Related Art A conventional non-contact sealing device of this type includes a sealing end surface 3a of a rotary sealing ring 3 fixed to a rotating shaft 2, a retaining ring 5 and a spring 6 attached to a seal case 1, as shown in FIG. A fluid film is formed between the sealing end surface 4a of the stationary sealing ring 4 which is energized and movable in the axial direction via the dynamic pressure generating groove 3b provided on the rotating side sealing end surface 3a. It is well known that a sealing portion S, which is a membrane forming portion, is configured to seal between a high pressure fluid region H and a low pressure fluid region L. Here, the stationary sealing ring 4 and the retaining ring 5 are connected to the spring 6 (
and fluid pressure) and are held in contact with each other in the axial direction.

0003

[Problem to be solved by the invention] By the way, each ring 3, 4
, 5, thermal strain and pressure strain occur due to heat generated during operation and system pressure of equipment. The thermal strain is mainly caused by heat generation due to the shear force of the seal portion S, and the amount of heat generated is equivalent to the amount of work due to the shear force of the fluid. That is, the shear force of a fluid is generally μ (V/h) (μ
: Viscosity, V: Peripheral velocity, h: Fluid film (sealed end surfaces 2a, 6a
The amount of work, or heat generation, due to this shearing force is the shearing force plus the area of the seal, the balance diameter, and the angular velocity.

[0004]Then, the amount of thermal strain occurring in each ring 3, 4, 5,
The amounts of pressure strain differ from each other because these rings 3, 4, and 5 are made of different materials having different coefficients of thermal expansion and Young's modulus due to their different functions. For example, the rotary sealing ring 3 is W
The stationary sealing ring 4 is made of a relatively soft material such as carbon, and the retaining ring 5 is made of a metal material such as SUS304 or Ti.

On the other hand, in the non-contact sealing device, since a fluid film is formed between both sealed end surfaces 3a and 4a, in order to exhibit a good sealing function, it is necessary to It is extremely important to maintain the smoothness and parallelism of both sealed end surfaces 3a, 4a.

However, in the conventional sealing device described above, the rotating sealing ring 3 is made of an ultra-hard material with a small coefficient of thermal expansion, so the amount of thermal strain and pressure strain is small; Regarding the ring 4 and the retaining ring 5, the amount of such distortion is large. Furthermore, at the contact portion 12 of the static sealing ring 4 with the retaining ring 5, the retaining ring 5, which has a different amount of strain and strain state, is strongly pressed against the stationary sealing ring 4 by the spring 6 and fluid pressure. , retaining ring 5
This distortion interferes with the stationary sealing ring 4, resulting in a different strain state from that generated only from the stationary sealing ring 4.

When the distortion of the stationary sealing ring 4 interferes with the distortion of the retaining ring 5 as described above, the smoothness of the stationary side sealing end surface 4a and the parallelism between this and the rotating side sealing end surface 3a are impaired, and as a result, , the pressure distribution in the seal portion S becomes inappropriate, and a good sealing function cannot be exhibited.

[0008] The present invention has been made in view of the above points, and is capable of properly maintaining the smoothness and parallelism of both sealed end faces by preventing excessive thermal strain and pressure strain, especially on the stationary side sealed end face. The object of the present invention is to provide a non-contact sealing device devised as described above.

[0009]

[Means for Solving the Problems] In order to achieve the above object, in the non-contact sealing device of the present invention, an O-ring is interposed between the stationary sealing ring and the retaining ring in the axial direction. By doing so, it is proposed to perform a sealing function and maintain the contactless state.

0010

[Operation] The stationary sealing ring and the retaining ring are held in a state where they are strongly pressed against each other by springs and fluid pressure, but this pressing is done through the O-ring, which is an elastic material, and there is no direct contact between the two rings. It is not done through contact.

Therefore, in the pressing parts of both rings, the strain of each ring is absorbed by the O-ring and does not interfere with the strain of the other ring, so even if the amounts of thermal strain and pressure strain of both rings are different, The strain distribution of the stationary sealing ring is not affected by the strain of the retaining ring. As a result, the smoothness of the stationary side sealed end face and the parallelism between this and the rotating side sealed end face are not impaired.

[0012] The stationary sealing ring and the retaining ring are well sealed by the O-ring. In addition, since the pressing force from the spring is applied from the retaining ring to the stationary sealing ring via the O-ring, the pressing force of the stationary sealing ring against the rotating sealing ring is maintained appropriately and does not have any adverse effect on the sealing function. .

[0013] In this way, the O-ring has, in addition to its original sealing function, the function of holding the stationary sealing ring and the function of absorbing strain.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be specifically explained below based on the embodiment shown in FIGS. 1 and 2.

In the non-contact sealing device shown in FIG.
2 is a seal case that partitions a high-pressure side sealed fluid region (for example, a high-pressure gas region inside a turbine or the like) H and a low-pressure side sealed fluid region (for example, an atmospheric region outside a turbine or the like) L; 2 is a seal; A rotary shaft such as a turbine shaft passing through the case 1; 3 a rotary sealing ring fixed to the rotary shaft 2; 4 a smooth sealing end surface 4 parallel to the sealing end surface 3a of the rotary sealing ring 3;
5 is a retaining ring held by the seal case 1 on the back side of the stationary seal ring 4; 6 is a spring interposed between the seal case 1 and the retainer ring 5.

For example, a spiral dynamic pressure generating groove 3b is formed on the rotation side sealing end surface 3a, and both sealing rings 3,
Dynamic pressure is generated with the relative rotation of 4, and a fluid film is formed between the sealed end surfaces 3a and 4a. That is, in the seal portion S, which is the portion where the fluid film is formed, the two sealed fluid regions H and L are sealed.

The stationary sealing ring 4 is made of carbon or the like, and is held by a retaining ring 5 via a drive pin 7 so as to be non-rotatable and relatively movable in the axial direction.

The retaining ring 5 is made of a metal material such as SUS304 or titanium and has a substantially L-shaped cross section and includes a cylindrical held portion 5a and an annular spring receiving portion 5b. It is held movable in the axial direction in a sealed state via a first O-ring 8 and non-rotatably via a drive pin 9. In addition, drive pins 7 and 9
can also be made common.

As shown in FIGS. 1 and 2, the stationary sealing ring 4 and the retaining ring 5 are maintained in a sealed, non-contact state by interposing a second O-ring 10.

That is, by fitting and holding the second O-ring 10 in a protruding manner into the annular groove 5d formed on the end surface 5c of the retaining ring 5, both rings 4 and 5 are held in the annular groove 5d formed on the end surface 5c of the retaining ring 5.
They are held so as to be pressed against each other via the second O-ring 10 in a non-contact state with an appropriate clearance 11a between them. Further, an annular convex portion 5e is provided on the end surface 5c of the retaining ring 5 and extends to the inner circumferential side wall of the annular groove 5d to prevent the second O-ring 10 from protruding or shifting in the inner circumferential direction. It has been devised as follows. In addition, in the holding ring 5, the outer diameter of the held portion 5a is set not to be larger than the outer diameter of the annular convex portion 5e. Further, an annular stepped portion 4c is formed on the inner peripheral portion of the stationary sealing ring 4, into which the annular convex portion 5e of the retaining ring 5 can be fitted with a slight clearance 11b.

In the non-contact sealing device constructed as described above, the stationary sealing ring 4 and the retaining ring 5 are not in direct contact with each other, but are pressed against each other via the second O-ring 10. Since the rings 4 and 5 are held in contact with each other, the thermal strain and pressure strain of the rings 4 and 5 are absorbed by the second O-ring 10, which is an elastic material, at the pressed portions, so that they do not interfere with each other. Therefore, the strain distribution of the stationary sealing ring 4 is not affected by the strain of the retaining ring 5. As a result, the smoothness of the stationary-side sealed end surface 4a and the parallelism with the rotating-side sealed end surface 3a are not impaired, and a good sealing function is exhibited over a long period of time.

Further, although the rings 4 and 5 are not in direct contact with each other, they are held in a state where they are pressed against each other via the second O-ring 10, so that the holding function of the stationary sealing ring 4 and The sealing function between both rings 4 and 5 will also be satisfactorily exhibited.

In particular, this function can be achieved by providing the stepped portions 4c and convex portions 5e on both rings 4 and 5, as described above, to prevent the O-ring 10 from protruding or shifting toward the inner circumference. This will ensure more reliable performance.

By the way, when the rotary shaft 2 axially oscillates or when the stationary side sealing elements 4 and 5 follow, the accompanying axial displacement of the stationary side sealing elements 4 and 5 is absorbed and dealt with by the first O-ring 8. Therefore, no load is applied to the second O-ring 10. Therefore, the strain absorption function of the stationary sealing ring 4 by the second O-ring 10 is not affected by shaft vibration or the like.

It should be noted that the non-contact sealing device of the present invention is not limited to the above-mentioned embodiments, but can be appropriately improved and changed without departing from the basic principles of the present invention. For example, the radial position where the second O-ring 10 is provided and the clearance between the rings 4 and 5 are appropriately set depending on conditions such as the shape of the constituent members and the fluid pressure. In particular, the radial position of the second O-ring is set in consideration of the strain absorbing function and holding function of the stationary sealing ring 4. Moreover, any means for forming a fluid film between both sealed end surfaces 3a and 4a is also available.

[0026]

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, the stationary sealing ring and the retaining ring need to be made of different materials due to their different functions. , the smoothness of the stationary side sealed end face and the parallelism between this and the rotating side sealed end face can be properly maintained for a long period of time, eliminating the inevitable drawbacks caused by the difference in the amount of pressure strain. It is possible to exhibit a good sealing function over a period of time.

[Brief explanation of drawings]

FIG. 1 is a half-cut sectional view showing an embodiment of a non-contact sealing device according to the present invention.

FIG. 2 is a detailed view showing an enlarged main part of FIG. 1;

FIG. 3 is a half-cut sectional view showing a conventional non-contact sealing device.

[Explanation of symbols]

1 Seal case 2 Rotation axis 3 Rotating sealing ring 3a　Rotation side sealed end surface 4. Stationary sealing ring 4a　Stationary side sealed end surface 5 Retaining ring 6 Spring 10 Second O-ring (O-ring) S　　　Seal part by fluid film

Claims (1)

[Claims] Claim 1: A fluid film sealing portion is provided between a rotating sealing ring fixed to a rotating shaft and a stationary sealing ring that is pressed against the rotating sealing ring via a retaining ring by a spring in a seal case. In the non-contact sealing device configured to form a stationary seal ring, the stationary seal ring and the retaining ring are maintained in a sealed non-contact state by interposing an O-ring in the axial direction. Non-contact sealing device