JP3312673B2 - Non-contact annular seal - Google Patents

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 more particularly to a rotary fluid machine such as a pump or a compressor, which contributes to the stability of a shaft system and reduces the amount of fluid leakage between impeller stages and the like. The present invention relates to a non-contact annular seal having a mechanism for performing the operation.

[0002]

2. Description of the Related Art As a non-contact annular seal, a smooth seal,
Seals with parallel grooves, screw grooves, spiral grooves, and seals mechanically processed on the inner peripheral surface, and dampers with a surface roughness provided on the inner peripheral surface of the seal by a mechanical or etching or other chemical surface treatment method There is a non-contact annular seal fixed to a casing such as a honeycomb seal in which a seal or a honeycomb material is welded or bonded to a cylindrical surface. There is also a damper seal or the like in which the sealed space of the annular seal is filled with oil or the like to pursue shaft stability.

[0003] Although a smooth seal is inexpensive to manufacture, it has relatively poor leakage characteristics, causes abnormal vibration of the shaft system, and has a high risk of seizure in the event of contact. Slotted seals such as parallel grooved seals have excellent leakage characteristics and have a low risk of seizing in the event that the rotating body comes into contact with the annular seal, but the shaft system may vibrate due to other rotating machine components. In this case, the effect of the stabilizing force acting on the shaft system is relatively small.

[0004] Damper seals and honeycomb seals are excellent in terms of leakage characteristics and stabilization of a shaft system, but they are bonded to a metal cylindrical surface by spot welding or a special bonding method, or a chemical surface treatment. There is a disadvantage that the manufacturing cost is high, such as providing a groove by the method. In addition, a mechanical seal or a damper seal having an oiling mechanism causes the oiling mechanism to increase the size of a rotary machine and increase costs.

[0005]

From the above prior art examples, the annular seals employed in the rotary machine have excellent surfaces but have disadvantages. It is important to minimize the above-mentioned disadvantages to improve the operation efficiency of the rotating machine, or to 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 leakage characteristics, contribution to stability of a shaft system, and cost performance.

[0007]

SUMMARY OF THE INVENTION A non-contact annular seal according to the present invention is a non-contact annular seal for reducing the amount of fluid leakage between impeller stages of a rotary fluid machine and sealing a rotating body with own liquid. The annular seal is axially fixed by interposing an axial fixing member made of an elastic material such as rubber between the casing and the casing installed outside the annular seal, thereby suppressing the axial movement of the annular seal. At the same time, 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,
In addition, the same fluid flows through 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 caused by abnormal vibration and the like, and the action of the fluid flowing through the gap between the inner circumferential surface of the casing and the outer circumferential face of the annular seal and the action of the axial fixing member. Thus, an elastic force and a damping force are generated with respect to the radial movement of the rotating body, thereby contributing to stabilization of the shaft system.

[0008]

According to a non-contact annular seal for reducing the amount of fluid leakage between impeller stages of a rotary machine such as a pump or a compressor, an annular fixing member such as rubber is sandwiched between a casing and a casing to fix the annular seal. The axial movement of the seal is elastically suppressed. Then, the fluid flows into the minute gap between the rotating body and the inner peripheral surface of the annular seal, and the same fluid and the same supply source also flow into 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 through 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, thereby contributing to the stability of the shaft system. Further, the fixing member such as rubber reduces the amount of leakage of the fluid flowing through 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 also absorbs the vibration of the rotating body by the spring force and the damping force to enhance the stability of the shaft system.

[0010] Further, by providing a groove or uneven surface roughness on the inner peripheral surface of the annular seal, the amount of leakage flowing through the gap between the rotating body and the non-contact annular seal can be reduced. Also, by providing a groove or uneven surface roughness on the inner peripheral surface of the casing, and / or by providing a groove or uneven surface roughness on the outer peripheral surface of the annular seal, the gap between the casing and the annular seal can be reduced. The amount of leakage flowing can be reduced.

[0011]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

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

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

In a rotary fluid machine such as a pump or a compressor, a non-contact annular seal 11 for reducing the amount of fluid leakage between the impeller stages and sealing the shaft is provided. An annular seal 11 is axially fixed by sandwiching a casing 12 provided on the outer periphery of the annular seal and an axial fixing member 13 made of an elastic member such as rubber opposed thereto. As shown in FIG. 3, the axial direction fixing member 13 is an
Since one end face is fixed to the end face 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 through 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. The fluid 14 having the same supply source as the fluid flows also in the minute gap between the fluids.

By 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, the annular seal 11 follows the radial movement of the rotating body 10 caused by abnormal vibration or the like, and Inner peripheral surface of casing 12 and annular seal 11
By the action of the fluid flowing through the gap on the outer peripheral surface of the shaft and the action of the axial fixing member 13 made of an elastic body such as rubber, an elastic force and a damping force are generated with respect to the radial movement of the rotating body, and the shaft system is stabilized. It is configured to contribute to the conversion.

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. 7, the gap between the rotating body 10 and the annular seal 11 is larger and smaller than the average circumferential gap. A fluid pressure for widening the gap is applied to a relatively small portion, and a fluid pressure for narrowing the gap is applied to a relatively large portion.

When the fluid pressure acts on the annular seal, as shown in FIG.
Moves in the radial direction so as to keep the gap with the rotating body 10 constant. However, the destabilizing force is generated by the restoring force and the circumferential flow component of the gap. Further, 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 of the annular seal through a small gap. And the minute gap becomes uneven in the circumferential direction.
On the other hand, a high fluid pressure acts on a relatively narrow gap portion and a low pressure acts on a relatively wide gap portion.
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. In other words, as shown in FIG. 4 (c), the annular seal 11 is moved only in the radial direction by the action of the fluid liquid film so as to keep the gap with the casing 12 constant in the circumferential direction. Prevent rotation movement.

As a result, the rotating body 10 also moves in the radial direction by the same action of the fluid liquid film so as to keep the gap between the rotating 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 machine components such as bearings, the bearing action to suppress the motion acts on the non-contact annular seal portion, contributing to the improvement of the stability of the shaft system. I do.

Further, by the above series of operations, the rotating body 1
Since the gap between 0 and the annular seal 11 is kept in a constant non-contact state, contact (seizure) between the rotating body 10 and the annular seal 11 can be prevented. Therefore, the gap between the rotating body 10 and the inner peripheral surface of the annular seal 11 is smaller than that of the conventional product.
It is possible to narrow it. By being able to narrow it, it is possible to reduce the amount of leakage at the same time. 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 very small, the leakage amount is extremely small. Help me.

Further, by providing a groove (for example, a parallel groove, a screw groove, or the like) 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. By providing grooves or irregularities for increasing the surface roughness on the surface of the rotating body 10 facing the inner peripheral surface of the annular seal 11, the amount of liquid leakage can be similarly reduced. Then, by inserting an axial fixing member 13 such as rubber between the annular seal and the casing,
It is possible not only to suppress a large axial movement caused by an axial fluid force acting on the non-contact annular seal 11, but also to apply a damping force to the vibration of the annular seal 11. .

The outer peripheral surface of the annular seal 11 and / or
Alternatively, by providing grooves or irregularities for increasing the surface roughness on the inner peripheral surface of the casing 12, the leakage amount can be further reduced. Since the supply source of the fluid flowing through the minute gap between the annular seal 11 and the rotating body 10 and the fluid flowing through the gap between the annular seal 11 and the casing 12 are the same, oil or the like is supplied from outside, such as a squeeze film damper. Since there is no need to supply, it is possible to reduce the size and cost of the rotary mechanical device itself.

Next, FIG. 5 shows a circumferential cross section of the annular seal 11 in which the high pressure side is relatively small and the low pressure side is relatively large. This is preferable because 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 changes linearly from the high pressure side to the low pressure side, but it may be changed stepwise or tapered including a curve.

As a better method, the annular seal is caused to move in the axial direction by an unbalanced fluid pressure caused by an axial pressure difference (or pulsation) between the high pressure side and the low pressure side of the fluid. For complete suppression, it is preferable to connect a spring 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 that a spring is inserted 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 the elastic member such as hard rubber is used as the axial member as in the above-described embodiment.
This is because the annular seal may be moved in the axial direction.

Further, it is more preferable to provide a detent pin between the annular seal and the casing so as to prevent the annular seal from rotating due to a fluid or the like. Thus, various modifications can be made without departing from the spirit of the present invention.

[0026]

According to the present invention as described above,
The rotating body can be sealed by reducing the amount of fluid leakage,
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 the drawings]

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

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

FIG. 3 is a sectional view taken along line AA ′ in FIG. 2;

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotating body 11 Annular seal 12 Casing 13 Fixing member

Continuation of the front page (56) References JP-A-53-117158 (JP, A) JP-A-57-195969 (JP, A) Japanese Utility Model Application No. 53-120672 (JP, U) Japanese Utility Model Application No. Sho 61-172261 (JP) , U) Japanese Utility Model Showa 58-1555459 (JP, U) Japanese Utility Model Showa 62-147766 (JP, U) Japanese Utility Model Utility Model No. 3-114678 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB Name) F16J 15/44 F16J 15/54

Claims (9)

(57) [Claims] 1. A non-contact annular seal for reducing the amount of fluid leakage between impeller stages of a rotary fluid machine and sealing a rotating body with self-liquid, both end surfaces of a concave portion of a casing accommodating the annular seal. An arc-shaped axial fixing member made of an elastic member for fixing the annular seal in the axial direction is arranged between the both ends of the annular seal in a circumferential direction. A non-contact annular seal, wherein the same fluid flows from a supply source to a minute gap between seal inner peripheral surfaces and a minute gap between the annular seal outer peripheral surface and the casing inner peripheral surface. 2. The non-contact annular member according to claim 1, wherein a groove or an uneven surface roughness is provided on an inner peripheral surface of the annular seal to reduce an amount of leakage between the rotating body and the annular seal. sticker. 3. The non-contact device according to claim 1, wherein an inner peripheral surface of the casing is provided with grooves or uneven surface roughness to reduce an amount of leakage between the annular seal and the casing. Annular seal. 4. The non-contact annular seal is provided with grooves or uneven surface roughness on an outer peripheral surface thereof to reduce a leakage amount between the annular seal and the casing.
A non-contact annular seal according to any one of claims 1 to 3. 5. The axial pressure of the fluid acting on the annular seal is balanced by making the circumferential cross section of the annular seal relatively small on the high pressure side and large on the low pressure side. The non-contact annular seal according to any one of claims 1 to 4, wherein 6. An inner peripheral surface of the annular seal, and / or
The non-contact annular seal according to any one of claims 1 to 5, wherein an outer peripheral surface changes stepwise or tapered in an axial direction from a high pressure side to a 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. A 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 a casing and the annular seal. Non-contact annular seal according to any one of claims 1 to 6. 9. provided detent mechanism between the annular seal and the casing, in such influence of the fluid flowing through the gap, any one of claims 1 to 8 wherein the annular seal is characterized by being prevented from rotating A non-contact annular seal according to claim 1.