KR20060019258A - Groove pattern of mechanical face seal - Google Patents

Abstract

The groove pattern structure of this invention consists of the Y-shaped groove 41, the straight groove | channel 42, the land part 47, and the dam part 48. As shown in FIG. The Y-shaped groove 41 has an inlet portion 43 is formed on the outer side of the rotor 11 in the radial direction, the outlet portion 44 is formed in the inner direction, the straight groove 42, The outer diameter direction is longer and the inner diameter direction is formed in a shorter trapezoidal shape.

Description

Groove pattern structure of mechanical face seal {GROOVE PATTERN OF MECHANICAL FACE SEAL}

1 is a view showing the structure of a general seal using the groove pattern of the present invention.

FIG. 2 is a diagram illustrating a part to which a groove is applied in FIG. 1.

3 is a perspective view showing a groove pattern structure according to the present invention.

FIG. 4 is a cross-sectional view taken along the line AA ′ of FIG. 3 and schematically showing the Y-shaped groove of the present invention.

5: is a figure which shows a straight groove | channel, FIG. 5 (a) is sectional drawing seen along the B-B 'line of FIG. 3, and FIG. 5 (b) is an enlarged plan view.

6 is a view schematically showing a land portion and a dam portion.

<Description of the symbols for the main parts of the drawings>

11: rotor 12: shroud

13: sleeve 14: means for applying force

16, 17, 23: O-ring 21: stator

41: Y-groove 42: straight groove

43: entrance of the Y-groove                 

44: exit of the Y-groove

45: center portion of the straight groove

46: end of straight groove

The present invention relates to a groove pattern structure used for a mechanical face seal, and more particularly, to a groove pattern structure that achieves a gas flow in the circumferential direction, and at the same time makes a gas flow returned to the outer diameter side again. It is about.

In general, a seal applied to a rotating shaft can be divided into two types.

One is that there is a direct contact between the two contact surfaces while the shaft is rotating. Such a seal is called a contacting seal. Contact seals have the advantage of easy design and low leakage, but wear and heat generation is high because the sealing surfaces are in contact. Therefore, good materials, hydro-pads, and face load reduction are essential. In addition, there is generally a relative limitation in operating pressure as compared to a non-contact seal.

The other is that there is no theoretical direct contact between the rotor and the stationary part. Such a seal is called a non-contacting seal. Non-contact seals are more difficult to design than the contact seals described above, and relatively little leakage occurs due to the small gaps between the sealing surfaces. However, there is less wear, there is a low heat generation, there is an advantage that can be applied to a high gas pressure environment. The mechanical seal having the groove pattern of the present invention belongs to such a non-contact seal.

Mechanical face seals have been developed to overcome the shortcomings of compression packing as devices absolutely necessary to prevent leakage of fluid on the rotating shaft. Advantages of mechanical face seals include: (1) prevention of visible leakage, (2) no abrasion of the shaft, and (3) all wear occurs only at the sealing surface, and (4) The seal is automatically compensated for as much as it is worn out, and the sealing is continued. In other words, the use of a mechanical face seal can reduce the leakage to a degree that satisfies the environmental regulations, and the maintenance cost can be reduced.

There are various ways of contactless seals. Basically all must be operable in a gaseous environment and the gas or liquid must be sealed even under pressure reversal. Non-contact seals form a thin gas film between the sealing surfaces for sealing and lubrication of the sealing surfaces.

The seal that makes a gas film between the sealing surfaces and seals it is called a gas seal. Areas of application for these gas seals include: (1) applications in the chemical industry, particularly where volatile hazardous air pollutants (VHAPs) are handled, and (2) new or existing double seals where safety, reliability, and emissions are critical factors. (double seal) (3) New and existing single seals where reliability and dry running due to cavitation are important factors.

The design of making this gas film of a non-contact seal is based on a hydrodynamic lift-off mechanism. A well known design is the spiral groove. Others include slotted face, wavy face and T-groove. The present invention relates to a pattern of grooves for making such a gas film.

On the sealing surface of a typical mechanical seal, a boundary layer of gas or liquid between the surfaces is lubricated. When designing a seal that meets the required leakage, service life, and energy consumption rate, the choice of a number of sealing surfaces should be chosen by considering the degree of lubrication between the surfaces. The present invention is specifically for lubrication by gas or gas among these various lubrication modes.

Among the patterns of various grooves for making a conventional gas film, a unidirectional groove is described in Korean Patent Application No. 10-1994-0019124 (name of the invention: machine surface seal). According to this technique, helical grooves in the machine face seal have a plurality of end corners that more evenly distribute the fluid pressure generated in the seal gap into individual pressure zones that may be disposed radially or circumferentially. .

However, this technique has the disadvantage that it can be applied only to rotation in a single direction. Therefore, even when the direction of rotation is different, or even the same size and shape depending on the arrangement in the double seal or the like must use different products for each direction of rotation. This reduces compatibility and greatly increases the burden of inventory. In addition, incorrect mounting may cause serious damage to the entire mechanical seal when operated in the opposite direction of rotation.                         

On the other hand, the conventional gas seal had a disadvantage that the gas consumption is large. For example, as in Korean Application No. 10-1992-0001981, in a structure in which the flow of gas is made only from the face outer diameter to the inner diameter due to the nature of the pattern, the gas is continuously removed from the face outer diameter in order to maintain continuous contact between the faces. It must flow into the inner diameter and therefore the gas on the inner diameter must escape to the atmosphere.

The present invention seeks to provide a bidirectional groove in which the groove can overcome this disadvantage of a single direction. According to the present invention, there is no need to distinguish according to the rotation direction, there is an advantage that the number and type of spare parts and assembly can be reduced by half. In addition, it is not necessary to consider the direction of rotation can be performed very easily and simply in assembling and installing the seal face.

In addition, the present invention is to provide a groove to achieve a flow in the circumferential direction to overcome the above-mentioned drawback of consuming a large amount of gas, and at the same time to create a flow of gas that is returned to the outer diameter again.

The flow of gas in the circumferential direction maintains non-contact between the continuous faces, which is the purpose of the original gas seal, and the flow of gas returned to the outer diameter returns the gas back to the outer diameter so that the gas does not leak to the face inner diameter and is wasted. It greatly reduces the consumption. At the same time, in the double seal, the inboard seal is used to release the impurity, which may be mixed in the gas, to the outside of the face so that it may not accumulate in the groove or be mixed into the pumping product.                         

According to the present invention, due to the flow and circulation of gas by this groove, the damage caused by heat by the cooling function that effectively lubricates between the sealing surfaces to minimize friction and wear on the contact surface and dissipate the generated heat as much as possible. And prevent sealing failure, and prevent inflow of impurity residues between sealing surfaces to prevent failure, thereby maximizing the life, performance, reliability and safety of the mechanical seal.

Hereinafter, with reference to the accompanying drawings, the configuration of the mechanical face seal according to the present invention will be described in more detail.

1 is a view showing the structure of a general seal using the groove pattern of the present invention, in which reference numeral 11 denotes a rotor and 21 denotes a stator.

Rotor 11 in FIG. 1 is configured to engage with a shroud 12 connected by a pin 15 to a sleeve or collar 13 coupled to a rotating shaft to rotate like a shaft. In contrast, the stator 21 is fixed to the housing 24 and configured to not rotate. The shroud 12 is configured to bring the rotor 11 into close contact with the stator 21 in response to a pressing force from the spring 14 to form a sealing surface between the rotor 11 and the stator 21. In addition, the O-rings 16, 17, and 23 block a path in which leakage may occur in addition to the sealing surface formed by the rotor 11 and the stator 21.

The sealing surface is realized by superimposing two very flat surfaces, both of which prevent leakage in the vertical direction of the axis. One of the two surfaces uses a material such as carbon-graphite so that galling does not occur, and the other one uses a relatively hard material. In addition, in order to prevent adhesion between the surfaces, the stator 21 and the rotor 11 use ones of different materials.

The grooves of the present invention have been developed to maximize the performance, reliability and safety of mechanical seals even in low lubricity environments. In addition, the lubrication at the interface is enhanced with the adjustment of the leakage level. It provides more reliable operation at lower cost without additional cooling, and greatly reduces friction at the contact surface for extended seal performance and longer life. Thus, for increased mean time between preventive maintenance (MTBPM), seal life can be used beyond that normally accepted by industry. Very low levels of leakage occur for increasingly demanding environmentally friendly operation.

This groove performs both directions of operation. This means a reduction in spare quantities and types of parts and assemblies. The same seals can be used at both ends in double suction pumps or beam compressors if the conditions, such as dimensions, are met. Allows for reverse rotation, so in reverse, in various situations, unlike unidirectional grooves, it does not harm seals and other equipment. In addition, it is not necessary to consider the direction of rotation can be performed very easily and simply in assembling, installing the seal face.

Hereinafter, the groove pattern of the present invention will be described in more detail with reference to FIGS. 2 to 5.

2 is a view showing a portion to which the groove according to the present invention is applied. As shown in Fig. 2, the groove according to the present invention is usually applied to the rotor 11, but may also be applied to the stator 21. Hereinafter, the case where it is applied to the rotor 11 is demonstrated as a representative.

3 is a view showing the groove according to the present invention shown in FIG. 2 in more detail. As shown in FIG. 3, the groove pattern structure by this invention consists of the Y-shaped groove 41, the straight groove | channel 42, the land part 47, and the dam part 48. As shown in FIG.

The Y-shaped groove 41 is formed in the radial direction of the rotor 11, the inlet portion 43 is formed in the outer diameter direction, that is, the outer portion, branched in the middle of entering the inner diameter direction, that is, inward direction from the inlet portion 43, As shown in FIGS. 3 and 6, the outlet portion 44 is located at the boundary between the land portion 47 and the dam portion 48. In addition, as shown in FIG. 4, the depth of the Y-shaped groove 41 is inclined so that the inlet 43 is deep and the outlet 44 is shallow. In addition, the width of the inlet 43 of the Y-shaped groove 41 is larger than that of the outlet 44.

In addition, the straight groove 42 is formed in a trapezoidal shape having a longer outer diameter direction and a shorter inner diameter direction. As shown in FIG. 5 (b), the trapezoidal long side portion is curved concave toward the outer diameter direction of the rotor 11, that is, outward. In addition, the depth of the straight groove 42 is formed so that the central portion 45 is larger than the end portion 46, the end portion 46 is formed so as to face the radially outward of the rotor (11) It is.

The gas flow in the mechanical seal of the present invention having the Y-shaped groove 41 and the straight groove 42 as described above will be described.

While the rotor 11 is rotating, gas enters the inlet 43 of the Y-groove 41. The gas entering the inlet 43 is collected at either of the two branched ends of the Y-shaped groove 41, that is, the outlet 44, according to the rotational direction of the rotor 11. As described above, the depth of the Y-shaped groove 41 is formed such that the inlet 43 is deep and the outlet 44 is shallow, and the width of the Y-shaped groove 41 is the inlet 43. Since it is formed larger than the (44) side, the gas is compressed at this outlet 44 side to form a high pressure zone. Thus, a strong hydrodynamic pressure and force is generated at this outlet 44 to separate the sealing surfaces with a reliable gas film, perform lubrication, and reduce face wear.

Then, the gas out of the high pressure region toward the exit 44 moves circumferentially through the land 47. The circumferentially moving gas passes through the straight grooves 42. While passing through this straight groove 42, part of the gas moves to the next Y-shaped groove 41 to form a continuous flow of gas. This gas flow maintains a continuous, stable non-contact of the sealing surface.

On the other hand, the rest of the gas passing through the straight groove 42 reaches the end portion 46 of the straight groove 42 and corresponds to the long side of the trapezoidal shape on the outer diameter side of the tip portion 46 as described above. It moves toward the outer diameter by the shape of the shape and exits the sealing surface and returns to the gas 30 in the sealing region.

The return action of the gas by the straight groove 42 is generated in the internal parts or serves to discharge debris, impurities, etc. introduced from the outside out of the sealing surface. As a result, it is possible to prevent these impurities from accumulating in the grooves and preventing the formation of the gas film, obstructing the gas flow, or damaging the sealing surface or the grooves themselves. Moreover, this return action also has the effect of cooling the face by dissipating heat generated in the sealing surface to the gas 30 in the sealing region.

The presence of this return gas means that the gas consumption of the groove design of the present invention is extremely low. In unidirectional helical grooves, the pumping action in the inward direction becomes stronger with rotation, whereas there is no circulation or return path, which eventually consumes a lot of gas. However, in the groove of the present invention, the flow in the circumferential direction is formed instead of the flow in the inner radial direction, and there is a return path, which can greatly reduce leakage to the atmosphere.

The dam part 48 is formed in this face inner diameter side. The dam portion 48 is not formed with a groove unlike the land portion 47 where the Y-shaped groove 41 and the straight groove 42 are formed. Accordingly, the dam portion 48 prevents leakage between the sealing surfaces even in the stationary state. In addition, during operation, the gas flows to the inner diameter to prevent leakage and prevents leakage even when the pressure state is reversed.

The groove of the present invention causes the flow and circulation of gas by its inherent pattern. By the Y-shaped groove and the straight groove according to the present invention, it is possible to form a continuous flow of gas, the flow and circulation of the gas can be effective lubrication between the sealing surface to minimize friction and wear on the contact surface In addition, the cooling function that dissipates the generated heat to the maximum prevents heat damage and sealing failure, and prevents impurities from remaining in the sealing surface in advance, causing trouble. Maximize performance, reliability and safety.

Claims (3)

A sleeve 13 coupled to the rotating shaft, a shroud 12 connected to the sleeve 13 by a pin 15, a rotor 11 coupled to the shroud 12 and configured to rotate like a shaft; A stator 21 fixed to the housing 23, a means 14 for applying a force to the shroud, and an O-ring 16, 17, 23, wherein the shroud 12 applies the force ( 14, the rotor 11 and the stator 21 are brought into close contact with each other to form a sealing surface between them, and the rotor 11 has a groove pattern structure of a mechanical face seal in which grooves are formed. In The groove pattern structure includes a Y-shaped groove 41, a straight groove 42, a land portion 47 in which the groove is formed, and a dam portion 48 in which the groove is not formed. The Y-shaped groove 41 has an inlet portion 43 is formed on the outer side in the radial direction of the rotor 11, the outlet portion 44 is formed in the inner direction, The linear groove 42 is a mechanical face seal, characterized in that formed in a trapezoidal shape is longer in the outer diameter direction, and shorter in the inner diameter direction. The depth of the inlet 43 is larger than the depth of the outlet 44, and the width of the inlet 43 is larger than the width of the outlet 44. The mechanical face seal which is formed large. The mechanical face seal according to claim 1 or 2, characterized in that the shape of the circumferential end portion (46) in the straight groove (42) is directed radially outward.

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