KR20170013532A

KR20170013532A - A Centrifugal Pump

Info

Publication number: KR20170013532A
Application number: KR1020150106287A
Authority: KR
Inventors: 이종천
Original assignee: 주식회사 에이치티에프
Priority date: 2015-07-28
Filing date: 2015-07-28
Publication date: 2017-02-07
Also published as: KR101837139B1

Abstract

The present invention relates to an air conditioner comprising a casing including an intake port, a discharge port and an impeller accommodation space, a bearing housing connected to the rear of the casing, a shaft supported by a ball bearing in the bearing housing to receive a driving force of the motor, A casing cover detachably coupled to the casing through a fastening member between the casing and the bearing housing and supporting the shaft; And a bleed seal assembly positioned inside the casing cover to seal the shaft rotation shaft; Wherein the bleed seal assembly comprises: a sleeve sealing the shaft outer circumferential surface; A bushing disposed on the outer circumferential surface of the sleeve at a predetermined interval; A seal cage integrally provided on an outer peripheral surface of the bushing; And a return rotor integrally provided on an outer circumferential surface of the sleeve; The present invention relates to a centrifugal pump including a centrifugal pump and a centrifugal pump.

Description

A Centrifugal Pump

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal pump, and more particularly, to a centrifugal pump provided on a shaft and including a sealing means for effectively preventing backflow and leakage of fluid discharged from an impeller.

A centrifugal pump is a device for discharging a fluid having increased pressure and velocity energy by a centrifugal force due to the rotation of the impeller at a high pressure and a high speed after flowing the fluid into a casing in which a rotating space of the impeller is secured.

1 is a view showing a conventional centrifugal pump.

1, a general centrifugal pump includes a casing 1 constituting a pump body, a grand packing 4 which is sandwiched between a bearing housing 5 and a middle portion of a casing cover 2 to support a shaft 7, And a shaft 7 which is supported by a bearing 6 inside the bearing housing 5 to receive the driving force of the motor and a shaft 7 integrally assembled to the front end of the shaft 7, And an impeller 3 for sucking and discharging the fluid.

The rotational force transmitted to the shaft 7 through the motor in the centrifugal pump described above causes the impeller 3 to rotate and the casing 2 having the inlet 1a, the discharge port 1b and the receiving space for the impeller 3, The central portion is evacuated by the rotation of the impeller 3 and the fluid is sucked. At this time, the fluid having undergone centrifugal force due to the rotation of the impeller 3 passes between the casing 1 and the casing cover 2 and is discharged to the outside through the discharge port 1b.

On the other hand, one of the biggest causes of failure of a pump in general is that the fluid passing through the pump leaks to components other than the impeller and the pump. Therefore, a system for preventing the fluid from leaking to the external environment is essential in the pump.

To this end, various sealing means are conventionally provided on the shaft axis behind the impeller to prevent axial leakage of the fluid, and in Fig. 1 there is shown a sealing means such as a grand and a grand packing.

The sealing means, such as the gland packing, can prevent the fluid flowing into the impeller from leaking to the rear of the impeller through the micro gap of the impeller shaft, which can not escape to the casing discharge port.

The sealing means, such as the above-mentioned gland packing, surrounds the circumference of the shaft shaft with the ground, forcibly inserts the gland packing into the gaps, compresses the gland packing in the axial direction, tightly seals the packing and shaft, tightens the fastening means such as bolts, , Wear of the packing, abrasion of the shaft (not shown) or a sleeve (not shown) surrounding the shaft is liable to occur, and leakage is liable to occur. (See Fig. 1)

In addition, when the pressure of the fluid in the pump acts at a high pressure and high pressure, the damage of the sealing means and the shaft is increased by the pressure of the fluid. Therefore, in order to continuously maintain the sealing state, There is an inconvenience in that the fastening means of the fastening means must be tightened from time to time and periodic replacement and maintenance work must be carried out.

Also, due to the structure of the gland packing, there is always a certain amount of water leakage, so that the maintenance cost is high, and the grease or oil impregnated in the gland packing causes water pollution.

As described above, since the problem of leakage of the fluid has an important influence on the performance of the pump, a micro-gap in the axial direction between the shaft and the casing cover prevents the pump from failing due to leakage of the fluid passing through the impeller, Means are required.

Korea Public Practice 1999-0022727

SUMMARY OF THE INVENTION It is an object of the present invention to provide a centrifugal pump improved in pump performance by maintaining watertightness between an impeller, a shaft, and a casing cover.

Another object of the present invention is to provide a centrifugal pump which can reduce wear of a sealing means provided between a shaft and a casing cover, thereby facilitating maintenance and improving the service life of the centrifugal pump.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to solve the above-mentioned problems, the present invention provides a bearing device comprising: a casing including an intake port, a discharge port and an impeller accommodation space; a bearing housing connected to the rear of the casing; a shaft supported by a ball bearing in the bearing housing, A casing cover detachably coupled to the casing through a fastening member and supporting the shaft between the casing and the bearing housing, the centrifugal pump including an impeller connected to an axial end of the shaft; And a bleed seal assembly positioned inside the casing cover to seal the shaft rotation shaft; Wherein the bleed seal assembly comprises: a sleeve sealing the shaft outer circumferential surface; A bushing disposed on the outer circumferential surface of the sleeve at a predetermined interval; A seal cage integrally provided on an outer peripheral surface of the bushing; And a return rotor integrally provided on an outer circumferential surface of the sleeve; And a centrifugal pump for rotating the centrifugal pump.

Further, the bushing may include a first bushing and a second bushing respectively provided at the front and rear of the return rotor, and the first bushing may have a predetermined first spacing distance from the outer circumferential surface of the sleeve wherein the second bushing includes a gap by a second spacing d2 between itself and the outer circumferential surface of the sleeve in labyrinth form, Pump.

The seal cage may include a first seal cage integrally formed on an outer circumferential surface of the first bushing and a second seal cage integrally formed on an outer circumferential surface of the second bushing,

Wherein the first seal cage includes a first flange portion at a rear side thereof and the second seal cage includes a second flange portion at a front side thereof and the engagement surfaces of the first flange portion and the second flange portion are in close contact with each other, And the coupling portion of the first flange portion and the second flange portion includes an internal space in which the return rotor is accommodated.

Further, according to the present invention, the seal cage further comprises a hole-shaped bypass hole through which one side of the pair of seal cages passes in a circumferential direction,

Wherein the bypass hole includes a first bypass hole provided on a first flange portion of the first seal cage and a second bypass hole provided on the second seal cage. to provide.

Further, in the present invention, the return rotor is accommodated in a space inside the engagement portion of the first flange portion and the second flange portion in association with the outer peripheral surface of the shaft shaft sleeve,

Wherein the blade includes a blade for conveying the flow of the fluid toward the impeller or for reducing the speed and pressure of the fluid.

According to the present invention as described above, the water tightness between the impeller, the shaft and the casing cover is maintained, and the pump performance is improved.

Further, according to the present invention, wear of the sealing means provided between the shaft and the casing cover is reduced, maintenance is easy, and the life of the pump is improved.

1 is a view showing a conventional pump.
2A is a cross-sectional view of a pump according to an embodiment of the present invention.
FIG. 2B is an enlarged view of the impeller portion of FIG. 2A.
FIG. 3A is a perspective view showing a sealing means applied to a pump according to an embodiment of the present invention, and FIG. 3B is a sectional view thereof.
4 is a schematic view showing an operating state of the sealing means according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. &Quot; and / or "include each and every combination of one or more of the mentioned items. &Lt; RTI ID = 0.0 >

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms " comprises "and / or" comprising "used in the specification do not exclude the presence or addition of one or more other elements in addition to the stated element.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

The terms spatially relative, "below", "beneath", "lower", "above", "upper" And can be used to easily describe a correlation between an element and other elements. Spatially relative terms should be understood in terms of the directions shown in the drawings, including the different directions of components at the time of use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element . Thus, the exemplary term "below" can include both downward and upward directions. The components can also be oriented in different directions, so that spatially relative terms can be interpreted according to orientation.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 shows a conventional pump, which is an example of a pump to which a sealing means by grand packing is applied.

Referring to FIG. 1, in order to prevent the fluid that has not been discharged to the discharge port from leaking to the rear side of the impeller and flow into the motor side, the rotation shaft of the shaft 7 for rotating the impeller 3, More precisely, the gland 8 and the gland packing 7 are applied as a sealing means for preventing fluid leakage between the impeller rear casing cover 2 through which the shaft 7 passes and the outer circumferential surface of the shaft.

However, the sealing means such as the above-mentioned gland packing is liable to cause leakage due to wear of the packing, abrasion of the shaft or wear of the sleeve due to the lapse of the pump use period, and when the pressure of the fluid in the pump acts at a high- The means and the shaft are damaged, and there is an inconvenience that the pump is disassembled and the fastening means such as a bolt is tightened or the maintenance work is frequently performed in order to increase the squeezed force.

In addition, there is always a certain amount of leakage due to the structure of the gland packing itself, so that the maintenance cost is high and the grease or oil impregnated in the gland packing is a cause of water pollution.

Meanwhile, in recent years, a mechanical seal is used for a pump as a sealing means for solving the problem of the above-mentioned gland packing. However, the cost is limited to 10 times or more as high as that of the grand packing. Most industrial pumps produced in Korea adopt the grand packing as the sealing means, and the expensive mechanical seal is applied to the high price pump of the petrochemical and plant industry.

In addition, the mechanical seal can not function as a sealing device when the pump is stopped due to shock caused by reverse rotation of the shaft, damage caused by rapid pressure change of the fluid, foreign substance penetration, and the like. It becomes.

As such, there is a risk of pump accident due to a large amount of effluent when the pump is damaged by mechanical or fluid shock, and the maintenance cost is high and maintenance of the operator is needed continuously.

On the other hand, the conventional sealing means can leak the fluid not only to the central axis of the impeller but also to the rear of the impeller (see FIG. 1). This is because the impeller is provided with a minute gap in order to reduce the abrasion due to the rotating friction on the impeller rotating side and the casing adjacent to the impeller outlet side adjacent to the discharge port when the impeller pressurizes the fluid introduced from the suction port and discharges to the discharge port.

Therefore, the high-speed and high-pressure fluid which can not escape into the discharge port is impregnated to the rear side of the impeller, that is, the motor side through the fine gap of the impeller outlet and the casing, do.

Further, since the rotating shaft of the shaft connected to the impeller shaft is axially coupled to the casing cover, even if the conventional sealing means is provided, the casing cover easily wears due to continuous use of the pump, The friction between adjacent portions increases with the axial coupling portion as the center. The wear is continuously intensified and the micro gap becomes wider.

As a result, the conventional sealing means is susceptible to wear due to interference with other components in the pump which are in contact with the shaft axis and friction with the shaft due to rotation of the shaft and the impeller, i.e., This causes a leakage of the fluid passing through the impeller due to a minute gap, which may cause the pump to break down, cause an accident, and shorten the service life.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pump that includes a sealing means for effectively preventing the leakage of fluid by improving the above-mentioned problems.

FIG. 2A is a cross-sectional view of a pump according to an embodiment of the present invention, and FIG. 2B is an enlarged view of the impeller portion of FIG.

FIG. 3A is a perspective view showing a sealing means applied to a pump according to an embodiment of the present invention, and FIG. 3B is a sectional view thereof.

2A and 2B, a structure of a pump according to an embodiment of the present invention includes a casing 110 including a suction port 111, a discharge port 112, and an impeller receiving space; A bearing housing (150) connected to the rear of the casing; A shaft 170 supported in the bearing housing by a ball bearing 160 to receive a driving force of the motor; And an impeller (130) connected to an axial end of the shaft (170); .

Also, in the present invention, a casing cover 120 may be provided between the casing and the bearing housing to detachably couple with the casing through a fastening member (B) and support the shaft.

At this time, a bearing housing 150 is disposed at the rear of the casing 110 having the discharge / suction port and is connected by a connecting bolt or the like. A casing cover 120 is interposed between the casing and the bearing housing, And a bleed seal assembly 200 which is a sealing means of the pump according to the present invention to support the shaft. In addition, a ball bearing 160 is mounted on the inside of the bearing housing 120 to rotatably support the shaft 170.

An inlet 131 for introducing the fluid is formed in the periphery of the front central axis of the impeller 130. A fluid is introduced from the casing inlet 111 through the inlet 131 and the pressure is increased along with the rotation of the impeller vane 133 Thereby discharging the fluid to the outlet 132.

The impeller 130 is integrally assembled to the shaft end of the shaft 170, and a driving motor (not shown) is connected to the other end of the shaft 170 to rotate the impeller 130. As a result, the impeller 130 connected to the end of the shaft rotates and the central portion is evacuated to suck the fluid into the casing inlet 111. At this time, the pressure of the fluid subjected to the centrifugal force is increased by the rotation of the impeller, (133), and is discharged to the outlet (132) through the casing outlet (112).

At this time, since the impeller outlet 132 includes a gap between the casing 110 and the casing cover 120, all the fluid discharged to the outlet port 132 does not escape to the discharge port 112, High-speed and high-pressure fluid leaks toward the casing cover 120 and flows to the sealing means, resulting in abrasion, etc., and the performance of the pump is deteriorated.

As described above, in the case of a pump in which a fluid pressure change is severe in the past, a sealing means such as a grand packing or a mechanical seal is frequently damaged due to mechanical or fluid shock. If the pump is not continuously inspected, It costs a lot.

Therefore, preventing leakage of the pump is a key to improve pump performance, and for this, the sealing means of the pump according to the present invention may include a bleed seal assembly.

In the embodiment of the present invention, the bleed seal assembly 200 is provided as a sealing means on the shaft 17 rotating inside the casing 110, more precisely on the outer circumferential surface of the shaft behind the rotating impeller 130 The sealing performance of the pump can be improved.

To this end, the bleed seal assembly includes: a sleeve 210 sealing the outer circumferential surface of the shaft 170; A bushing 220 spaced apart from the outer circumferential surface of the sleeve 210 by a predetermined distance; A seal cage 230 integrally formed on an outer peripheral surface of the bushing 220; And a return rotor (240) integrally provided on an outer circumferential surface of the sleeve (21); . &Lt; / RTI >

At this time, the sleeve 210 is cylindrical and surrounds the outer circumferential surface of the shaft 170, and is inserted and protected by the shaft.

The bushing 220 and the seal cage 230 are provided in a noncontact manner spaced apart from the outer circumferential surface of the sleeve 210 by a predetermined distance in the circumferential direction and unlike the rotating shaft 170, maintain.

Further, the clearance d between the sleeve and the bushing includes a minute gap between the bushing and the sleeve, so that fluid leaked through the gap is impregnated. The flow state of the leakage fluid through the bushing and the seal cage will be described later with reference to FIG.

Unlike the bushing 220 and the seal cage 230 which are spaced apart from the shaft and remain fixed, the return rotor 240 is integrally formed from the outer circumferential surface of the sleeve 210 in the circumferential direction So that it is maintained in the same operating state as that of the shaft since it is in contact with the sleeve fixed to the shaft 170. That is, when the shaft rotates, the return rotor also rotates, and when the shaft stops, the return rotor also stays in a stopped state. The flow state of the leakage fluid through the return rotor will be described later with reference to FIG.

Subsequently, the bushing 220 and the seal cage 230 may be provided in front of and behind the return rotor 240, respectively.

That is, the bushing 220 includes a first bushing 220a and a second bushing 220b provided at the front and rear of the return rotor 240, respectively, A first seal cage 230a integrally provided on the outer circumferential surface of the first bushing 220a and a second seal cage 230b integrally formed on the outer circumferential surface of the second bushing 220b.

The first bushing 220a has a cylindrical shape similar to that of the sleeve 210 and has a gap between the sleeve 210 and the first bushing 220a at a predetermined first separation distance d1 .

The second bushing 220b has a labyrinth shape provided on the outer circumferential surface of the sleeve 210 and also has a second spacing interval between the sleeve 210 and the second bushing 220b. (d2).

That is, the first bushing 220a and the second bushing 220b serve as non-contact type sealing means for preventing frictional resistance due to contact motion with the sleeve 210 surrounding the shaft shaft, the speed of the fluid is gradually reduced as the fluid flows between the gaps defined by the first spacing d1 and the second spacing d2, thereby enhancing the sealing performance and increasing the life of the pump.

The labyrinth of the second bushing 220b may be formed by alternately arranging a plurality of fins or ring-shaped metal or an elastic material such as a ceramic or a carbon composite material in a passage through which the fluid is lost, And the fluid passing through the second bushing passes through the narrow gap and the wide gap formed by the labyrinth rinse several times alternately, and the pressure and the velocity energy of the fluid are lost, and as a result, the fluid is prevented from leaking .

Meanwhile, in the embodiment of the present invention, a hole 221 may be formed at one side of the second bushing 220b of the labyrinth shape. The fluid passing through the labyrinth gradually decreases in speed and then passes through the hole 221 to the second bypass hole 232b described later.

The first seal cage 230a and the second seal cage 230b provided at the front and rear of the return rotor 240 may include a flange portion 231. [

That is, the first seal cage 230a includes a first flange portion 231a on the rear side and the second seal cage 230b may include a second flange portion 231b on the front side, The first flange portion and the second flange portion can be tightly coupled with each other so that the fluid does not leak.

The return rotor 240 includes an internal space 233 in which the return rotor 240 is accommodated, and the return rotor 240 includes a first flange 231a and a second flange 231b, The first flange portion 231a and the second flange portion 231b and is coupled with the shaft shaft sleeve 210 to be rotatable as described above, And is rotated or stopped according to the operating state of the shaft 170.

The seal cage 230 may further include a bypass hole 232 for discharging the leakage fluid passing through the gap d between the sleeve 210 and the bushing 220 .

A bypass pipe (not shown) is connected to the end of the bypass hole 232 to transfer or drain the fluid leaked from the impeller to the suction port 111. The fluid conveyed or drained to the suction port 111 is introduced into the pump And discharged or discharged to the discharge port 112 through the impeller 130 repeatedly.

3A and 3B, the bypass hole 232 may be provided on the first seal cage 230a and the second seal cage 230b, respectively, and more precisely, The first bypass hole 232a may be included in the first flange portion 231a of the first seal cage and the second bypass hole 232b may be formed on the second seal cage 230b.

The first bypass hole 232a has a hole shape having one side in the circumferential direction of the first flange portion 231a and a return rotor 240 provided in the inner space 233 of the first flange portion. As shown in Fig. Accordingly, the high-speed, high-pressure fluid flows in the motor-side direction through the gap between the sleeve 210 and the first bushing 220a and flows backward or forward by the rotational force of the return rotor 240, The pressure and the pressure of the first bypass hole 232a are reduced, and the first and second bypass holes 232a and 232a are connected to the pump inlet 111, respectively.

The second bypass hole 232b is formed in a hole shape through which one side of the second seal cage 230b passes in the circumferential direction and communicates with a hole 221 passing through a side surface of the second bushing . Therefore, the fluid left without being able to escape to the first bypass hole 232a of the first seal cage 230a flows through the gap between the second bushing 230b and the sleeve 210 due to the labyrinth separation distance d2 The speed and pressure are continuously reduced while being finally passed through the second bypass hole 232b to the pump suction port 111, or drained.

The return rotor 240 provided between the first seal cage 230a and the second seal cage 230b and closely attached to the outer circumferential surface of the sleeve 210 fixed on the axis of the shaft 170 rotates the blade 241).

In the embodiment of the present invention, the blade 241 provided in the return rotor 240 has a shape of a wing for controlling the flow of fluid, similar to the impeller 130, and has a wing direction opposite to the impeller .

The fluid flowing into the impeller 130 is discharged to the impeller center axis or the impeller center axis rather than to the discharge port 112 by the blade 241 of the return rotor 240. [ When the fluid leaks to the motor-side shaft 170 through the rear of the impeller, the high-speed, high-pressure fluid hits the blade 241, and strikes the fluid in a direction opposite to that in which the fluid leaks toward the motor side, Even if a part of the fluid passes through the return rotor, the velocity and the pressure of the fluid to be leaked are reduced.

Next, the leakage fluid whose speed and pressure have been reduced in one or two stages through the first bushing 220a and the return rotor 240 is transferred to the second bushing 220b and the second seal cage 230b to further reduce the speed and pressure of the fluid and to escape through the second bypass hole 232b formed on the second bushing and the second seal cage. Thus, the high-speed, high-pressure fluid leaking to the rear of the impeller is finally conveyed or drained to the pump inlet 111 through the second bypass hole 232b.

Next, how the flow of the fluid leaking to the rear of the impeller is controlled by the sealing means of the pump according to the embodiment of the present invention will be described.

4 is a schematic view showing an operating state of the sealing means according to the present invention.

Generally, in the case of a centrifugal pump, the fluid introduced into the impeller 130 through the inlet port 111 passes through the impeller, increases in speed and pressure, and is discharged to the discharge port 112 at a high speed and high pressure.

However, when the impeller pressurizes the fluid introduced from the suction port and discharges the fluid to the discharge port, a fine gap is provided on the impeller exit side adjacent to the pump discharge port 112 in order to reduce wear caused by rotational friction on the rotating impeller and the casing The fluid can leak to the impeller rearward as well as the central axis of the impeller.

Referring to FIG. 1, it can be seen that the fluid can leak not only to the center axis of the impeller but also to the rear of the impeller as shown by arrows.

Accordingly, since the high-speed, high-pressure fluid that has not yet escaped into the discharge port is impregnated to the rear side of the impeller, that is, the motor side through the fine gap of the impeller outlet and the casing, do.

However, according to the schematic diagram of FIG. 4, the high-speed and high-pressure fluid that has passed through the impeller by means of the bleed seal assembly 200 serving as the sealing means according to the present invention reduces the speed and pressure of the leaked fluid over three stages, do.

The high-speed, high-pressure fluid that has not been able to escape to the discharge port 112 in the first stage and is lost to the impeller center shaft or the impeller rearward can be separated from the gap d1 between the sleeve 210 on the shaft and the first bushing 220a, Through the gap created by the fluid passage, to the rear side of the motor side, and the fluid velocity and pressure are primarily reduced.

Subsequently, a part of the fluid that has escaped to the rear of the motor in the second step is escaped by the first bypass hole 232a provided in the first flange 231a of the first seal cage 230a, The blade 241 of the return rotor 240 rotating on the shaft axis hits the fluid and transports the fluid forward, A part of the fluid flows out to the first bypass hole 232a and a part of the fluid is conveyed between the gap by the distance d1 between the sleeve and the first bushing, .

Meanwhile, the first bypass hole 232a is connected to the pump suction port 111 by a bypass pipe (not shown). Therefore, the fluid that has escaped through the first bypass hole 232a is conveyed or drained to the pump inlet 111 along the bypass pipe, so that the impeller passes and discharges together with the fluid flowing into the pump.

Finally, in step 3, in step 2, the fluid that has leaked through the return rotor 240 without passing through the first bypass hole 232a is separated from the second bushing 220b and the sleeve 210 And flows through the gap due to the interval d2. At this time, the flow velocity and the pressure of the leaked fluid have already passed through the constituent devices of the first and second stages of the bleed seal assembly, and are greatly reduced and small.

Accordingly, the low-speed low-pressure leakage fluid passes between the second bushing 220b in the form of a labyrinth and the gap of the sleeve, and the velocity and the pressure gradually decrease. Finally, the second bushing 220b and the labyrinth- And then passes through the second bypass hole 232b formed in the second seal cage 230b formed integrally with the outer surface of the second bushing.

The fluid that has escaped through the second bypass hole 232b is connected by a bypass pipe (not shown) and is transported or drained to the pump suction port 111 through the bypass pipe, The impeller is repeatedly passed and discharged.

As described above, the pump to which the bleed seal assembly 200 as the sealing means according to the embodiment of the present invention is applied is easy to maintain because the leaked fluid has a prefabricated structure in which the speed and pressure are reduced stepwise in three stages. That is, since the primary flow rate is reduced by the first bushing, the secondary flow rate is reduced by the return rotor, and the tertiary flow rate is reduced by the secondary bushing, the mechanical damage and the shock due to the leakage fluid are reduced.

Meanwhile, the bleed seal assembly 200 may be manufactured by manufacturing a sleeve, a bushing, a seal cage, and a return rotor by a casting method or an injection molding method, respectively, and then assembling the assembly. Therefore, partial replacement and repair due to wear of the component can be facilitated.

Conventionally, due to the characteristics of the centrifugal pump, the pressure fluctuation of the fluid in the pump is so severe that high-speed, high-pressure fluid causes damages to the sealing means and the shaft. In order to continuously maintain the sealing state, It is necessary to perform the parts replacement and repair work. However, according to the present invention, the mechanical damage is reduced by the gradual leakage preventing means by the three steps, the life is increased, and the sealing means can be easily repaired by a simple assembled structure.

As described above, since the pump including the bleed seal assembly according to the present invention is a non-contact type sealing means unlike the prior art, there is no fear of occurrence of mechanical accident due to a rapid pressure change of the fluid and the pressure at the shaft shaft sealing portion is gradually reduced, The lifetime is remarkably improved because frequent abrasion, sudden accidental risk and overall damage of the pump do not occur due to changes in the pressure of the fluid.

Therefore, the watertightness between the impeller, the shaft and the casing cover is ensured so that the operation failure due to the leakage, the corrosion of the peripheral parts and the water pollution do not occur and the pump can be replaced with the sealing means. have.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: centrifugal pump 110: casing
120: casing cover 130: impeller
140: Grand packing 150: Bearing housing
160: Bearing 170: Shaft
200: sealing means 210: sleeve
220: Bushing 230: Seal cage
240: Return rotor

Claims

A bearing housing connected to the rear of the casing, a shaft supported by a ball bearing in the bearing housing to receive a driving force of the motor, and an impeller connected to an axial end of the shaft, wherein the impeller includes a casing including a suction port, In the centrifugal pump,
A casing cover detachably coupled to the casing through a fastening member between the casing and the bearing housing and supporting the shaft; And
A bleed seal assembly located inside the casing cover to seal the shaft rotation shaft; Lt; / RTI >
Wherein the bleed seal assembly comprises:
A sleeve sealing the outer circumferential surface of the shaft;
A bushing disposed on the outer circumferential surface of the sleeve at a predetermined interval;
A seal cage integrally provided on an outer peripheral surface of the bushing; And
A return rotor integrally provided on an outer circumferential surface of the sleeve; And a centrifugal pump.

The method according to claim 1,
The bushing
And a first bushing and a second bushing provided respectively in front and rear of the return rotor,
Wherein the first bushing includes a gap defined by a first spacing d1 between the sleeve and the outer circumferential surface of the sleeve,
Wherein the second bushing includes a labyrinth-shaped gap with the outer circumferential surface of the sleeve at a predetermined second spacing distance d2.

3. The method of claim 2,
The seal cage,
A first seal cage integrally formed on an outer circumferential surface of the first bushing, and a second seal cage integrally formed on an outer circumferential surface of the second bushing,
The first seal cage including a first flange portion at the rear,
The second seal cage including a second flange portion forwardly,
Wherein the coupling surfaces of the first flange portion and the second flange portion are in close contact with each other and the coupling portion of the first flange portion and the second flange portion includes an internal space in which the return rotor is accommodated Centrifugal pump.

The method of claim 3,
The seal cage,
Further comprising a hole-shaped bypass hole through which one side of the twisted seal cage passes in the circumferential direction,
Wherein the bypass hole includes a first bypass hole provided on a first flange portion of the first seal cage and a second bypass hole provided on the second seal cage.

4. The method according to any one of claims 1 to 3,
The return rotor includes:
A first flange portion and a second flange portion which are engaged with an outer circumferential surface of the shaft shaft sleeve and are accommodated in an inner space of a coupling portion of the first flange portion and the second flange portion,
Wherein the blades, including the blades, convey the flow of fluid in the direction of the impeller or reduce the velocity and pressure of the fluid.