JP2000120557A - Seal device of fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently regulate flow speed of a seal part, suppress leaking flow, and prevent self-excited vibration of a rotary shaft by changeably forming a seal part passage shape using a shape memory alloy and bimetal for a material for forming a fin part or a groove part of a seal part. SOLUTION: In a turbo machine, after passing through a space (a) a fluid passes an impeller 11, and discharged to a passage 10. A part thereof passes a clearance (b) formed on a back surface of the impeller 11, and leaks from a space (d) passing through a seal part passage 15. The seal part passage 15 is divided into several chambers by fins 17 attached on a seal ring 16, and a flow rate of the fluid leaked from the seal part passage 15 is reduced by energy loss caused by friction when the fluid passes those chambers. In this time, the fin 17 is formed of shape memory alloy or bimetal. When a fluid temperature in a seal changes, the fin 17 is deformed. It is thus possible to reduce leaking flow of the seal part, and it is also possible to prevent self-excited vibration of a rotary shaft 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device inside a fluid machine, which reduces or prevents leakage of a fluid from a high-pressure portion to a low-pressure portion, and that a fluid force generated in a seal acts on a rotating shaft. The present invention relates to a technique for preventing self-excited vibration of a rotating shaft caused by a cause.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 2-130296 discloses a conventional sealing device for reducing or preventing a leakage flow rate from a seal portion by changing the shape of the seal. In this patent, a shaft seal of a turbomachine having a rotating shaft and an impeller attached to the rotating shaft, and having a shaft sealing mechanism in a shaft penetrating portion of a casing that separates a high pressure region and a low pressure region on an impeller outlet side. In the apparatus, a means for flowing a coolant inside the seal member of the shaft sealing mechanism, and a means for detecting a gap between the rotating shaft and the seal member are provided, and the amount of refrigerant flowing into the seal member is determined according to a detection value of the detection means. Controlling.

[0003] As a conventional seal device for preventing self-excited vibration of a rotating shaft caused by a fluid force generated in a seal acting on the rotating shaft, as disclosed in JP-A-58-152974, Uniform circumferential imbalance of fluid pressure in the clearance between the rotating part and the fixed part is achieved by a shaft sealing device that has a space part that communicates in the circumferential direction at the part distant from the open end of the honeycomb seal fixed to the fixed part. To prevent self-excited vibration of the rotating shaft.

[0004]

In the prior art as described above, for example, when the entire seal is cooled, a gap is opened between the casing and the seal when the seal shrinks, and the entire seal is cooled. There is a problem that a large amount of cooling water is required in order to do so.

[0005] In an example of preventing self-excited vibration of the rotating shaft caused by the fluid force generated in the sealing device acting on the rotating shaft, the fluid efficiently enters and exits between the play space and the space. Therefore, the pressure is not sufficiently diffused into the space, and there is a problem that the action of equalizing the fluid pressure imbalance in the circumferential direction in the circumferential direction is not sufficient.

An object of the present invention is to reduce or prevent a leakage flow in a seal portion by changing a shape of a flow passage in the seal portion, and to cause a fluid force generated in the seal to act on a rotating shaft. An object of the present invention is to provide a sealing device for a fluid machine that prevents self-excited vibration of a rotating shaft.

[0007]

The object of the present invention is to change the shape of the flow path of the seal by changing the shape of the flow path of the seal using a shape memory alloy or a bimetal as a material for forming the fins or grooves of the seal. Can be adjusted efficiently, thereby reducing or preventing leakage flow,
It is possible to prevent self-excited vibration of the rotating shaft caused by the fluid force generated in the seal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described. FIG. 1 shows an example in which the present invention is used for a labyrinth seal of a turbo machine. In FIG. 1, 11 is an impeller, 1
Reference numeral 2 denotes a rotating shaft, and 13 denotes a casing. A sleeve 14 is fitted on the rotating shaft, and the sleeve 14 and the seal ring 16
There is a seal part flow path 15 between them. The arrows in the figure indicate the direction of the flow, and the flow passing through a is discharged to the flow path 10 after passing through the impeller 11, but a part of the flow passes through the gap b on the back of the impeller and c Through the seal portion flow path 15 and d
Leaks from

Generally, the seal portion flow path 15 is
The room is divided into several rooms by the fins 17 attached to the space 6, and the flow rate of leakage from the seal portion flow path 15 is reduced by utilizing energy loss due to friction when the fluid passes through these rooms.

In FIG. 1, the fins are provided on both the sleeve 14 and the seal ring 16, but may be provided on only one side. There are various shapes of the fins 17.

Referring to FIG. 2, a description will be given of a method of controlling a leakage flow of a seal portion according to the present invention. (A) is the sleeve 14
This shows a case where fins are provided only on the fin, and the leakage flow is controlled by the gap width e between the fin tip and the seal ring 16. The arrows in the figure indicate the direction of flow. In the present invention, the fin 1
7 is characterized in that a shape memory alloy or a bimetal is used, and a fin shape is deformed by temperature to control a leakage flow.

For example, when the rotating machine is started, the fins 17
In order to increase the gap width e so that the seal ring 16 does not come into contact with the seal ring 16 and reduce the gap width e at the time of rated rotation to reduce the leakage flow, the fin shape shown in FIG. The fluid temperature at this time is made possible by deforming the fin 17 into the shape shown in FIG.

When a shape memory alloy or bimetal is used for the fin portion, when the fluid temperature in the seal changes from T1 to T2 while the fluid temperature in the seal changes from time t1 to t2 as shown in FIG. When the fluid temperature inside the seal changes from T1 to T2 as shown in FIG. 3 (b), the effect shown in FIG. 2 can be realized by using a material that changes the deformation amount of the fin from d1 to d2. You. Since the gap width e in FIG. 2 is a function of the temperature T, it is represented by e (T). If the gap width at the temperature T1 is e0, the gap widths are e (T1) = e0, e (T
2) = e0− (d2−d1).

By using the fins 17 for both the sleeve 14 and the seal ring 16 as shown in FIG. 4, the leakage flow rate can be reduced efficiently. There are various fin shapes other than those shown in FIG.
For example, a fin shape as shown in FIG. 5 is also conceivable. FIG.
In this case, it is possible to reduce the leakage flow at the time of high-speed rotation by deforming the fin shape as shown in (a) and (b).

FIG. 6 shows a method of deforming the fin portion by giving a temperature change to the fin portion made of a shape memory alloy or bimetal from the outside, separately from the case of using the fluid temperature in the seal. (A) is a method in which a fluid such as cooling water or hot water is caused to flow through the fin portion to give a temperature change to the fin portion, and (b)
Is a method of giving a temperature change using a heating means such as a heater. 18A is a flow path for cooling water or the like, and the cooling water flows in the direction of the arrow. Also, 19 in (b) indicates a heater.

FIG. 7 shows an example in which a groove is provided instead of a fin in the seal portion flow path of the sleeve 14 and the seal ring 16 of FIG. 1 and a "groove ring 20" for changing the depth of the groove is provided. It is. The groove 20 is made of a shape memory alloy or a bimetal, and the temperature of the groove changes to change the depth of the groove as shown in FIGS. In this embodiment, the same cooling / heating means as in FIG. 6 can be used.

Although the method for reducing or preventing the leakage flow in the seal portion has been described above, a method for preventing the self-excited vibration of the rotating shaft caused by the fluid force generated in the seal portion of the rotating machine will be described below. . The self-excited vibration of the rotating shaft is generated when the circumferential pressure in the seal becomes uneven due to the eccentricity of the rotating shaft and a fluid force acts on the rotating shaft. This self-excited vibration can be prevented by increasing the width of the gap in the seal. The gap width in the seal can be realized by increasing the gap width e in FIG. 2 or increasing the groove depth in FIG. Therefore, self-excited vibration of the rotating shaft can be prevented by deforming the flow path shape of the seal portion using a shape memory alloy or a bimetal for the fin portion or the groove portion of the seal portion. As a method of changing the shapes of the fins and the grooves in order to prevent self-excited vibration of the rotating shaft, it is of course possible to use the cooling / heating means of FIG.

In the above description, an example is shown in which the present invention is applied to a rotating machine such as a turbomachine. However, the present invention is naturally applicable to a sealing device of a fluid device other than the rotating machine. For example, the present invention can be applied to a sealing device having a very narrow flow path such as a micromachine.

[0019]

According to the present invention, the shape of the fin portion and the groove portion of the seal portion is deformed to reduce or prevent the leakage flow of the seal portion, and the rotation caused by the fluid force of the seal portion acting on the rotating shaft. It is possible to prevent self-excited vibration of the shaft.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a labyrinth seal of a turbo machine which is Embodiment 1 of the present invention.

FIGS. 2A and 2B are partial cross-sectional views showing an example of the fin shape of FIG. 1;

FIGS. 3A and 3B are characteristic diagrams when a fin portion is deformed.

4A and 4B are cross-sectional views showing an example of a fin shape.

FIGS. 5A and 5B are cross-sectional views showing an example of a fin shape.

FIGS. 6A and 6B are cross-sectional views showing an example of a groove shape.

FIGS. 7A and 7B are cross-sectional views illustrating an example of a cooling / heating method of a fin portion.

[Explanation of symbols]

11 impeller, 12 rotating shaft, 13 casing, 14
... sleeve, 16 ... seal ring.

Claims (1)

[Claims] 1. A sealing device inside a fluid machine, wherein a shape memory alloy or a bimetal is used for a fin or a groove, or a material of both the fin and the groove, and the shape of the fin or the groove is changed. Sealing device for fluid machinery.