RU2425271C1 - Seal with zigzag-shaped pins - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: pin-type seal includes annular parts adjacent to each other, each of which includes pins uniformly distributed in circumferential direction and formed by means of slots made in annular parts. At least one of annular parts has protruding platforms made as an integral part of the corresponding pins. Annular parts are installed so that pins of each annular part can cover the slots of other annular part adjacent to it. Slots and pins formed between them have zigzag shape mating to each other.

EFFECT: invention allows increasing efficiency of pin-type seal at considerable deviations of rotor during operation and improving reliability of the seal owing to better flexibility of pins.

5 dwg

Description

The invention relates to the field of turbo and engine building and can be used in the construction of gas turbine engines and steam turbines for sealing radial clearances.

The presence of radial clearances in the flowing part of gas turbine equipment is necessary to eliminate the "jamming" of the rotor and stator during operation. Thus, there is a need to install seals in the flow part, which allow to minimize the flow of the working medium (gas, steam, oil) through the annular gap between the rotor and stator (between the working blades and the nozzle apparatus, shaft and housing, etc.).

One of the most effective classes of radial clearance seals is finger seals. A common disadvantage of the known designs of finger seals is that they have fingers with a relatively simple structural form - in the form of a cantilever fixed rod of small curvature. As a result, the fingers are not flexible enough to compensate for significant rotor deflections. This does not allow them to be used for large rotor deviations.

A reversible finger seal is known, containing at least two pairs of thin ring parts folded into a stack, each of which contains an annular array of radially and tangentially entering fingers, between which there are gaps. The ring parts of each of the pairs are arranged so that the fingers of one ring part overlap the slots in the other. Moreover, the fingers of the ring parts of one of the pairs are located at an angle in the clockwise direction, and the fingers of the ring parts of the other pair are in the counterclockwise direction [US 5031922, F16J 15/447, 07/16/1991].

The disadvantage of this seal is that it cannot compensate for significant deviations of the rotor due to thermal and mechanical deformation, because the shape of the fingers is not optimal in terms of the elastic properties of this design. The insufficient flexibility of the fingers leads to the fact that during operation due to excessive compression of the sealing surface, burns may occur on the contacting surfaces of the fingers and the rotor surface, a decrease in power on the motor shaft, and increased wear of the contacting pairs.

The closest in technical essence to the proposed one is a finger seal containing two adjacent ring parts, each of which contains fingers evenly spaced around the circumference, formed by making slits in the ring parts, at least one of which has protruding pads made integrally with the corresponding fingers, and the annular parts are mounted so that the fingers of each annular part overlap the slots adjacent to the other ring Second part. All fingers have the same thickness and are separated from each other by the same slots. Fingers have a curvature defined by an exponential expression [US 5755445, F16J 15/447, 05.26.1998].

The disadvantage of this invention, as well as the previous one, is the insufficiently high flexibility of the fingers, which does not allow it to be used with significant deviations of the rotor during operation. Another disadvantage of this seal is that due to the one-sided tilt of the fingers (clockwise or counterclockwise), it cannot be used for efficient sealing of rotors with the possibility of reverse movement.

The technical result of the claimed invention is to increase the efficiency of the finger seal with significant deviations of the rotor during operation and increase the reliability of the seal by improving the flexibility of the fingers.

The indicated technical result is achieved in that the finger seal contains annular parts adjacent to each other, each of which contains fingers evenly spaced around the circumference, formed by making slits in the annular parts, at least one of which has protruding pads made in one piece with the corresponding fingers, and the annular parts are mounted so that the fingers of each annular part overlap the slots of the adjacent other annular part, the slit and azovannye fingers therebetween are reciprocal to each other zigzag shape.

In addition, the width of the fingers in any section perpendicular to their axis is less than the thickness of the annular part.

The implementation of the ring parts with slots and the fingers formed in a zigzag shape between them allows you to increase the flexibility of the fingers, reduce wear and eliminate damage to the contacting pairs, which, accordingly, increases the efficiency and reliability of the finger seal.

The proposed design of the finger seal is explained in the schematic drawings.

Figure 1 schematically shows an isometric view of a finger seal; figure 2 is an enlarged isometric view of the finger seal with a cross section in the axial plane, figure 3 is an enlarged fragment of the annular part of the finger seal in the radial plane; figure 4 is an isometric view of the components of a finger seal; figure 5 is an isometric view of the finger seal and the shaft being sealed.

The finger seal consists of two annular parts 1 and 2 adjacent to each other (Fig. 1), each of which contains zigzag fingers 3 and 4 evenly spaced around the circumference (Figs. 2, 3), between which there are zigzag slots mating to them 5 and 6. On the annular part 1, located on the side of the low-pressure cavity, there are protruding pads 7 made in one piece with the corresponding fingers 3. The annular parts 1 and 2 are oriented through the through holes 8 (made in the annular parts 1 and 2) and positioned ( getting) relative to each other so that the fingers of each annular gap between overlapping parts fingers in the other annular part, and the width of the fingers more than the width of the slits.

In an expanded embodiment of the design of the finger seal, the annular parts 1 and 2 can be pressed from the side of the low and high pressure cavities by the ring caps 9, 10 (Fig. 4) to increase the rigidity of the structure in the axial direction.

A package of annular parts 1, 2 and annular covers 9, 10 can be secured using connecting elements, for example rivets (not shown in the drawings) located in through holes 8 around the circumference of a finger seal.

To increase the mechanical stability of the fingers, their width in any section perpendicular to the axis of the finger should be less than the thickness of the annular part.

The above description of the finger seal is made for the case of using two ring parts with fingers, but does not exclude the use of a larger number of ring parts.

Finger seal works as follows.

Between the rotor part 11 (Fig. 5) and the fingers 3 and 4, the minimum allowable clearance is set, which is selected from the condition that the rotor part 11 does not touch the protruding pads 7 during normal operation (depending on the dimensions of the rotor and the operating conditions, the gap is 0.05 ... 0.2 mm).

In the process of starting and changing the engine operating mode, when significant deviations of the rotor part 11 occur, the fingers 3 and 4 come into contact with the surface of the rotor part 11. In this case, the fingers 3 and 4 are deformed, which prevents “jamming” of the rotor and stator parts.

Unlike finger seals with a simple finger shape, the proposed design has increased elastic properties, which allows the use of this seal with significant rotor vibrations without compromising the performance of the structure.

Another advantage of the proposed design is that the protruding platforms due to the zigzag shape of the fingers deviate mainly in the radial direction, which allows you to use this design to seal rotors with the possibility of reverse movement (figure 5).

To obtain zigzag gaps of finger seals, the most rational is the use of pulsed electrochemical processing, the main advantages of which are the following: no wear of the electrode tool during processing, no thermally changed layer, sharp edges and burrs on the treated surface, the ability to simultaneously process all inter-finger grooves with a special electrode tool with many zigzag protrusions, fairly low processing error (not more than 20 ... 30 microns), good indicators of roughness (R _a 0,2 ... 1,25 mm - depending on the material).

Thus, the proposed invention due to the increased flexibility of the zigzag fingers allows you to use it with significant rotor deviations during operation, and also increases the reliability of the seal by reducing wear and the likelihood of damage to the contacting pairs.

Claims (1)

A finger seal containing annular parts adjacent to each other, each of which contains fingers evenly spaced around the circumference, formed by making slits in the annular parts, at least one of which has protruding pads made in one piece with the corresponding fingers, the ring the parts are installed so that the fingers of each annular part overlap the slots of the adjacent other annular part, characterized in that the slots and the finger formed between them and have a zigzag shape reciprocal to each other.

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