JPH08121610A - Non-contact annular seal - Google Patents

Abstract

PURPOSE: To provide a non-contact annular seal excellent in the leaking characteristic, the contribution to the stability of the shaft system, and the cost. CONSTITUTION: An annular seal 11 is fixed in the axial direction by holding a fixing member 13 made of the elastic material such as rubber between the annular seal and a casing 12 installed on the outside of the annular seal 11 to reduce the leakage flowing in the small clearance between the outer circumferential surface of the annular seal 11 and the inner circumferential surface of the casing 12, and to allow the fluid whose supply source is identical to flow in the small clearance between the outer circumferential surface of a body of revolution and the inner circumferential surface of the annular seal 11, and the small clearance between the outer circumferential surface of the annular seal 11 and the inner circumferential surface of the casing 12 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact annular seal, and particularly contributes to the stability of the shaft system in rotary fluid machines such as pumps and compressors, and reduces the amount of fluid leakage between impeller stages. The present invention relates to a non-contact annular seal having a mechanism for operating.

[0002]

2. Description of the Related Art As a non-contact annular seal, a smooth seal,
Parallel grooved seal, thread grooved seal, spiral grooved seal mechanically machined on the inner peripheral surface, and damper with surface roughness provided on the inner peripheral surface of the seal by a mechanical surface treatment method such as mechanical or etching There is a non-contact annular seal fixed to a casing such as a seal or a honeycomb seal in which a honeycomb material is welded or adhered to a cylindrical surface. There is also a damper seal or the like in which the space sealed by the annular seal is filled with oil or the like to pursue the stability of the shaft.

Although a smooth seal has a low manufacturing cost, it has a relatively poor leak characteristic, and has a high risk of seizure if it should come into contact with the shaft system due to abnormal vibration of the shaft system. A grooved seal such as a parallel grooved seal has excellent leakage characteristics and has a low risk of seizure in the unlikely event that the rotating body comes into contact with the annular seal, but other rotary machine components cause the shaft system to vibrate. In this case, the effect of the stabilizing force acting on the shaft system is relatively small.

Further, although the damper seal and the honeycomb seal are excellent in terms of leak characteristics and the effect of stabilizing the shaft system, they are bonded to the metal cylindrical surface by spot welding or a special bonding method, or chemically surface-treated. There is a drawback that the manufacturing cost is high, such as providing a groove by the method. Further, in the mechanical seal or the damper seal having the oil supply mechanism, the oil supply mechanism causes an increase in the size of the rotary machine and an increase in cost.

[0005]

According to the above-mentioned prior art examples, the annular seals employed in the rotary machine have excellent surfaces, but also have drawbacks. It is important to reduce the above-mentioned drawbacks as much as possible in order to improve the operating efficiency of the rotating machine, improve the reliability during operation, reduce the cost, and reduce the size of the rotating machine.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-contact annular seal excellent in leak characteristics, contribution to the stability of a shaft system, and cost performance.

[0007]

The non-contacting annular seal of the present invention is a non-contacting annular seal for axially sealing a rotating body with its own liquid to reduce the amount of fluid leakage between impeller stages of a rotating fluid machine. , The axial seal is axially fixed by sandwiching an axial fixing member made of an elastic material such as rubber between the annular seal and a casing installed outside the annular seal, and suppressing the axial movement of the annular seal. At the same time, the amount of leakage that flows through the minute gap between the outer peripheral surface of the annular seal and the inner peripheral surface of the casing is reduced,
In addition, the same fluid is supplied from the same supply source to the minute gap between the outer peripheral surface of the rotating body and the inner peripheral surface of the annular seal, and the minute gap between the outer peripheral surface of the annular seal and the inner peripheral surface of the casing. By the action of the fluid flowing between the inner peripheral surfaces of the annular seal,
The annular seal follows the radial movement of the rotating body due to abnormal vibration, and the action of the fluid flowing in the gap between the inner peripheral surface of the casing and the outer peripheral surface of the annular seal and the action of the axial fixing member. Thus, elastic force and damping force are generated with respect to the radial movement of the rotating body, which contributes to stabilization of the shaft system.

[0008]

With regard to the non-contact annular seal that reduces the amount of fluid leakage between the impeller stages of rotary machines such as pumps and compressors, an annular fixing member such as rubber is sandwiched and fixed between the casing and the casing to form an annular shape. Elastically restrains axial movement of the seal. Then, while the fluid flows in a minute gap between the rotating body and the inner peripheral surface of the annular seal, the fluid having the same supply source as the fluid also flows in the minute gap between the outer peripheral surface of the annular seal and the inner peripheral surface of the casing. Flowing. By the action of the fluid flowing in the gap between the rotating body and the inner peripheral surface of the annular seal, the annular seal follows the movement of the rotating body in the radial direction, and between the inner peripheral surface of the casing and the outer peripheral surface of the annular seal. Due to the action of the fluid and the action of the axial fixing member, a spring force and a damping force are generated with respect to the radial movement of the rotating body, which contributes to the stability of the shaft system. Further, the fixing member such as rubber reduces the leakage amount of the fluid flowing in the minute gap between the outer peripheral surface of the annular seal and the inner peripheral surface of the casing.

Therefore, the fixing member made of an elastic material such as rubber remarkably reduces the amount of fluid leakage, and absorbs the vibration of the rotating body by the spring force and the damping force to improve the stability of the shaft system.

Further, by providing a groove or uneven surface roughness on the inner peripheral surface of the annular seal, it is possible to reduce the amount of leakage flowing through the gap between the rotating body and the non-contact annular seal. In addition, by providing a groove or uneven surface roughness on the inner peripheral surface of the casing, and / or providing a groove or uneven surface roughness on the outer peripheral surface of the annular seal, a gap between the casing and the annular seal is formed. It is possible to reduce the leak amount that flows.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view showing an example in which the present invention is applied to an actual rotary machine. The non-contact annular seal 11 is provided in the concave portion of the casing 12 and seals the impeller 19 fixed to the rotating shaft 18 which is the rotating body 10. In the gap between the annular seal 11 and the rotating body 10, the fluid itself pressurized by the impeller 19 flows, so that the annular seal 11
Seals the rotating body 10 with its own liquid.

FIG. 2 is a vertical sectional view of a non-contact annular seal portion according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along the line AA '.

In a rotary fluid machine such as a pump or a compressor, a non-contact annular seal 11 for sealing the shaft by reducing the amount of fluid leakage between impeller stages and the like is arranged. The annular seal 11 is fixed in the axial direction by sandwiching a casing 12 installed on the outer peripheral portion of the annular seal and an axial direction fixing member 13 facing the casing 12 and made of an elastic member such as rubber. As shown in FIG. 3, the axial fixing member 13 has an annular seal 1 in an arc shape.
Since the one end surface is fixed to the end surface of the concave portion of the casing 12, the amount of leakage flowing through the minute gap between the outer peripheral surface of the annular seal and the inner peripheral surface of the casing is reduced. Further, the axial movement of the annular seal is suppressed, the fluid 14 flows into a minute gap between the outer peripheral surface of the rotating body 10 and the inner peripheral surface of the annular seal, and the outer peripheral surface of the annular seal and the inner peripheral surface of the casing are The fluid 14 having the same supply source as that of the fluid also flows in a minute gap therebetween.

The action of the fluid flowing between the outer peripheral surface of the rotating body 10 and the inner peripheral surface of the annular seal 11 causes the annular seal 11 to follow the radial movement of the rotating body 10 due to abnormal vibration, and Inner peripheral surface of casing 12 and annular seal 11
Due to the action of the fluid flowing through the gap on the outer peripheral surface of the rotor and the action of the axial fixing member 13 made of an elastic body such as rubber, elastic force and damping force are generated against the radial movement of the rotating body to stabilize the shaft system. It is configured to contribute to

FIG. 4 shows the operation of the non-contact annular seal of this embodiment. Abnormal vibration occurs in the rotating body 10, and FIG.
When the rotating body 10 moves in the radial direction, as shown in FIG. 5, the gap between the rotating body 10 and the annular seal 11 can be larger or smaller than the circumferential average gap. A fluid pressure that tends to widen the gap is applied to a relatively small portion, and a fluid pressure that tends to narrow the gap is applied to a relatively large portion.

As the fluid pressure acts on the annular seal, the non-contact annular seal 11 as shown in FIG. 4 (b).
Moves in the radial direction so as to keep a constant gap with the rotating body 10. However, the destabilizing force is generated by this restoring force and the circumferential flow component of this gap. In addition, as described above, the annular seal 11 follows the movement of the rotating body 10, and the outer peripheral surface of the annular seal 11 and the inner peripheral surface of the casing 12 installed on the outer periphery through a minute gap with the annular seal. The minute gap between and becomes uneven in the circumferential direction, and the annular seal 1
1, a high fluid pressure is applied to a relatively narrow gap and a low pressure is applied to a relatively wide gap.
1 tries to return to the central axis.

This gap has no circumferential flow component,
Since it is only the axial component, it has the effect of stabilizing the movement of the seal. That is, as shown in FIG. 4C, the action of the fluid liquid film causes the annular seal 11 to move in the radial direction so that the gap between the annular seal 11 and the casing 12 is constant in the circumferential direction. Prevents rotational movement.

As a result, the rotary body 10 also moves in the radial direction by the action of the similar fluid liquid film so as to keep the gap between the rotary body 10 and the annular seal 11 constant, returns to the central axis, and is stabilized. . This state is shown in FIG. In other words, even when the rotating body vibrates due to other rotating fluid mechanical components, the bearing action that suppresses the motion of the rotating body acts on the non-contact annular seal portion, contributing to the improvement of the stability of the shaft system. To do.

Further, by the series of operations described above, the rotating body 1
Since the gap between 0 and the annular seal 11 is kept in a constant non-contact state, it is possible to prevent the contact (seizure) between the rotating body 10 and the annular seal 11. Therefore, compared with the conventional product, the gap between the inner peripheral surface of the rotating body 10 and the annular seal 11,
It is possible to narrow it. By making it possible to narrow it, at the same time, it becomes possible to reduce the amount of leakage. Further, since the fixing member 13 such as rubber between the casing 12 and the annular seal 11 makes the cross-sectional area of the inflow and outflow of the fluid at the inlet and the outlet between the casing 12 and the annular seal 11 extremely small, the leakage amount is extremely small. End

Further, by providing grooves (for example, parallel grooves, screw grooves, etc.) or unevenness having a large surface roughness on the inner peripheral surface of the annular seal 11, it is possible to further reduce the amount of fluid leakage. become. Similarly, the amount of liquid leakage can be reduced by providing a groove or unevenness for increasing the surface roughness on the surface of the rotating body 10 facing the inner peripheral surface of the annular seal 11. Then, by sandwiching the axial direction fixing member 13 such as rubber between the annular seal and the casing,
Not only it is possible to suppress a large axial movement caused by the axial fluid force acting on the non-contact annular seal 11, but also a damping force can be applied to the vibration of the annular seal 11. .

The outer peripheral surface of the annular seal 11 and /
Alternatively, it is possible to further reduce the amount of leakage by providing a groove or unevenness for increasing the surface roughness on the inner peripheral surface of the casing 12. Since the supply source of the fluid flowing through the minute gap between the annular seal 11 and the rotating body 10 is the same as the supply source of the fluid flowing through the gap between the annular seal 11 and the casing 12, oil such as squeeze film damper is not supplied from the outside. Since it is not necessary to supply the rotary machine, the rotary machine itself can be downsized and the cost can be reduced.

Next, FIG. 5 shows a cross section of the annular seal 11 in the circumferential direction in which the high pressure side is relatively small and the low pressure side is relatively large. It is preferable that the force for moving the annular seal in the axial direction due to the difference between the fluid pressure applied to the annular seal 11 on the high pressure side and the fluid pressure applied to the annular seal 11 on the low pressure side can be balanced and canceled. In the embodiment shown in FIG. 5, the outer peripheral surface is linearly changed from the high pressure side to the low pressure side, but it may be changed into a stepped shape or a tapered shape including a curved line.

As a better method, the axial movement of the annular seal due to the unbalanced fluid pressure caused by the axial pressure difference (or pulsation) on the high-pressure side and the low-pressure side of the fluid is applied to the annular seal. In order to suppress completely, it is preferable to connect springs sealed from a fluid in parallel in addition to an elastic material such as rubber. Alternatively, as shown in FIG. 6, it is more preferable to insert a spring into a hollow rubber-like elastic material to form an axial member between the casing and the annular seal. When the pressure difference between both ends of the annular seal is extremely large, only an elastic material such as hard rubber is used as the axial member as in the above-mentioned embodiment.
This is because the annular seal may be moved in the axial direction.

Furthermore, it is more preferable to provide a detent pin between the annular seal and the casing to prevent the annular seal from rotating due to fluid or the like. As described above, various modified embodiments are possible without departing from the spirit of the present invention.

[0026]

According to the present invention as described above,
The amount of fluid leakage can be reduced and the rotating body can be sealed with a shaft.
In addition, the stability of the bearing can be improved. Further, the manufacturing cost can be reduced due to the simple structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a pump showing an arrangement position of a non-contact annular seal.

FIG. 2 is a vertical sectional view of a non-contact annular seal according to an embodiment of the present invention.

3 is a cross-sectional view taken along the line AA ′ in FIG.

FIG. 4 is a sectional view showing the operation of the non-contact annular seal.

FIG. 5 is a vertical cross-sectional view of a non-contact annular seal according to another embodiment of the present invention.

FIG. 6 is a vertical sectional view of a non-contact annular seal according to another embodiment of the present invention.

[Explanation of symbols]

 10 Rotating Body 11 Annular Seal 12 Casing 13 Fixed Member

Claims (9)

[Claims] 1. A non-contact annular seal for axially sealing a rotating body with its own liquid by reducing the amount of fluid leakage such as between the impeller stages of a rotary fluid machine, between a casing installed outside the annular seal. The annular seal is axially fixed by sandwiching an axial fixing member made of an elastic material such as rubber between the annular seal and the axial movement of the annular seal is suppressed, and at the same time, between the annular seal outer peripheral surface and the casing inner peripheral surface. The amount of leakage flowing through the minute gap is reduced, and the supply source is the same for the minute gap between the outer peripheral surface of the rotating body and the inner peripheral surface of the annular seal and the minute gap between the outer peripheral surface of the annular seal and the inner peripheral surface of the casing. A fluid flows, and the action of the fluid flowing between the outer peripheral surface of the rotating body and the inner peripheral surface of the annular seal causes the annular seal to follow the radial movement of the rotating body due to abnormal vibration, and the casing. Inner peripheral surface and outside of the annular seal By the action of the fluid flowing through the gap in the peripheral surface and the action of the axial fixing member, elastic force and damping force are generated with respect to the radial movement of the rotating body, which contributes to the stabilization of the shaft system. Non-contact annular seal to be used. 2. The non-contact ring according to claim 1, wherein the inner peripheral surface of the ring seal is provided with grooves or uneven surface roughness to reduce a leakage amount between the rotating body and the ring seal. sticker. 3. The non-contact according to claim 1, wherein the inner peripheral surface of the casing is provided with a groove or an uneven surface roughness to reduce a leakage amount between the annular seal and the casing. Annular seal. 4. The non-contact annular seal is provided with a groove or an uneven surface roughness on an outer peripheral surface thereof to reduce a leakage amount between the annular seal and the casing.
The non-contact annular seal according to any one of claims 1 to 3. 5. The axial cross-section of the annular seal is relatively small on the high pressure side and large on the low pressure side so that the axial pressure of the fluid acting on the annular seal is balanced. The non-contact annular seal according to any one of claims 1 to 4. 6. The inner peripheral surface of the annular seal, and / or
The non-contact annular seal according to any one of claims 1 to 5, wherein the outer peripheral surface changes in a step shape or a taper shape in the axial direction from the high pressure side to the low pressure side. 7. The non-contact annular seal according to claim 1, wherein a spring sealed from a fluid is connected in parallel to the axial fixing member. 8. The rubber-like elastic material constituting the axial fixing member is hollow, and a spring is inserted into the rubber-like elastic material so as to connect the casing and the annular seal. The non-contact annular seal according to any one of claims 1 to 6. 9. The rotation preventing mechanism is provided between the annular seal and the casing to prevent the annular seal from rotating under the influence of a fluid flowing through the gap. The non-contacting annular seal according to claim 1.