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Title:
A ROTARY UNION
Document Type and Number:
WIPO Patent Application WO/2004/090964
Kind Code:
A1
Abstract:
The present invention provides a rotary union that couples a rotary part to a stationary part while being capable of supplying a variety of fluids to a desired part. The rotary union includes an outer housing (2) having a bore (22), with a plurality of fluid oultets (24) formed on a sidewall of the outer housing; an intermediate housing (4) having a shaft hole (42), and inserted into the bore (22) of the outer housing (2) to be rotated; a feed shaft (6) having a plurality of fluid channels (62), and inserted into the shaft hole (42) of the intermediate housing (4); and a plurality of sealing members (43 and 46) placed around the inner surface of the outer housing and around the outer surface of the feed shaft to be in contact with the outer and inner surfaces of the intermediate housing (4), thus sealing a fluid.

Inventors:
RHEE HEE-JANG (KR)
Application Number:
PCT/KR2004/000833
Publication Date:
October 21, 2004
Filing Date:
April 10, 2004
Export Citation:
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Assignee:
SHIN WON CO LTD (KR)
RHEE HEE-JANG (KR)
International Classes:
H01L21/304; F16L39/06; H01L21/00; H01L21/687; (IPC1-7): H01L21/304
Domestic Patent References:
WO1990009053A11990-08-09
Foreign References:
US6085782A2000-07-11
DE4027623A11992-03-12
JPH1034407A1998-02-10
JP2001141149A2001-05-25
JP2002323185A2002-11-08
Attorney, Agent or Firm:
Kwon, Hyuk-sung (1330-9 Seocho-dong Seocho-gu, Seoul 135-858, KR)
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Claims:
Claims
1. A rotary union mounted at an end thereof to a rotary part (100) and coupled at an opposite end thereof to a fluid supply unit (200) connected to a fluid supply source, the rotary union comprising : an outer housing (2) having a bore (22) therein, with a plurality of fluid outlets (24) formed on a sidewall of the outer housing to communicate with the bore (22); an intermediate housing (4) having a shaft hole (42) therein, and inserted into the bore (22) of the outer housing (2) to be rotated, the intermediate housing being mounted at an end thereof to the rotary part (100) and at an opposite end thereof to a drive unit (300); a feed shaft (6) having a plurality of fluid channels (62) therein, and inserted into the shaft hole (42) of the intermediate housing (4), the feed shaft being mounted at an end thereof to the fluid supply unit (200); and a first sealing unit and a second sealing unit to prevent a leakage of a fluid, the first sealing unit being interposed between the outer housing (2) and the intermediate housing (4), and the second sealing unit being interposed between the intermediate housing (4) and the feed shaft (6).
2. The rotary union according to claim 1, wherein the first sealing unit comprises a plurality of first sealing members (43 or 43a); and the second sealing unit comprises a plurality of second sealing members (66 or 66b).
3. The rotary union according to claim 2, wherein each of the first and second sealing members (43 and 66) comprises a seal ring (430,660), with an annular groove (433,663) of a predetermined depth formed along a side surface of the seal ring, a reinforcing member (432,662) inserted into the annular groove, and a sealing edge (431,661) formed along an outside edge of an outer surface of the seal ring.
4. The rotary union according to claim 2, wherein each of the first sealing members (43a) comprises an annular seal ring (430a) with a curved lip (431a) formed along an inner surface thereof; and each of the second sealing members (66b) comprises an annular seal ring (660b) with a curved lip (661a) formed along an outer surface thereof.
5. The rotary union according to any one of claims 2 through 4, wherein the first sealing unit further comprises a plurality of first fixing rings (45); the second sealing unit further comprises a plurality of second fixing rings (65); both a second bearing (28) and a third bearing (26) are interposed between the outer housing (2) and the intermediate housing (4); and both a fourth bearing (61) and a fifth bearing (63) are interposed between the intermediate housing (4) and the feed shaft (6), wherein the plurality of first sealing members (43 or 43a) and the plurality of first fixing rings 45 are alternately placed between the second and third bearings (28 and 26), and the plurality of second sealing members (66 or 66b) and the plurality of second fixing rings (65) are alternately placed between the fourth and fifth bearings (61 and 63).
6. The rotary union according to any one of claims 1 through 4, wherein the intermediate housing (4) has a plurality of coolant outlet paths (44) that are formed in a sidewall of the intermediate housing (4) in lengthwise directions, and a plurality of path holes (440) that are formed through the sidewall of the intermediate housing (4) at positions between the plurality of coolant outlet paths (44) to communicate with the shaft hole (42), wherein the intermediate housing is mounted at the end thereof to the rotary part (100), with a first bearing (48) interposed between the intermediate housing and the rotary part.
7. The rotary union according to any one of claims 1 through 4, wherein the feed shaft (6) has a coolant inlet path (64) that is formed through a center of the feed shaft in a lengthwise direction, a plurality of fluid channels (62) having different lengths that are formed in a sidewall of the feed shaft in lengthwise directions while being spaced out at regular intervals, and a plurality of fluid inlets (640) that are formed on an outer surface of the feed shaft to communicate with ends of the fluid channels (62), wherein the drive unit (300) is supported around the end of the feed shaft with a bearing interposed between the drive unit and the shaft.
8. The rotary union according to claim 5, wherein the intermediate housing (4) has a plurality of coolant outlet paths (44) that are formed in a sidewall of the intermediate housing (4) in lengthwise directions, and a plurality of path holes (440) that are formed through the sidewall of the intermediate housing (4) at positions between the plurality of coolant outlet paths (44) to communicate with the shaft hole (42) ; the feed shaft (6) has a coolant inlet path (64) that is formed through a center of the feed shaft in a lengthwise direction, a plurality of fluid channels (62) having different lengths that are formed in a sidewall of the feed shaft in lengthwise directions while being spaced out at regular intervals, and a plurality of fluid inlets (640) that are formed on an outer surface of the feed shaft to communicate with ends of the fluid channels (62) ; and each of the first and second fixing rings (45 and 65) has a plurality of through holes (450,650) therein, wherein the fluid flowing from the fluid inlets (640) of the feed shaft (6) passes through the through holes (450 and 650), and is discharged through the fluid outlets (24) of the outer housing (2) at the moment the fluid inlets (640), the through holes (450 and 650), the path holes (440), and the fluid outlets (24) are aligned with each other while the feed shaft (6), the intermediate housing (4), the outer housing (2), and the rotary part (100) are rotated together by an operation of the drive unit (300).
Description:
A ROTARY UNION Technical Field The present invention relates, in general, to a rotary union which couples a rotary part to a stationary part while being capable of supplying a cleaning fluid to a desired part, and in more detail, to a rotary union which is provided in an outer housing with both an intermediate housing and a feed shaft to supply a fluid while an end of the intermediate housing is installed on a rotary part to be rotated, and which efficiently prevents a leakage of a variety of fluids that flow to the outer housing through the feed shaft in a pressurized or vacuum state.

Background Art Generally, semiconductor equipment has been used for mass- production of integrated circuits (IC) that are important semiconductor devices useful in a variety of industrial fields.

In other words, integrated circuits are layered on a circuit board of a silicon device. In the above-mentioned IC layering process, a polishing process must be executed using an apparatus for chemical-mechanical polishing (CMP) applications.

In the CMP process, a polishing pad that contains deionized water, an etching solution and a chemical including polishing slurries is rotated on an active surface of a circuit board of a

silicon device while being in contact with the active surface, thus causing a chemical-mechanical reaction on the active surface to remove impurities from the surface and increase the smoothness of the surface.

The apparatus for CMP applications is provided with a rotary union to supply a fluid from a stationary part to a rotary part.

The rotary union is a rotary pipe coupling device that can supply a pressurized fluid or another fluid under a vacuum pressure lower than the atmospheric pressure from a stationary pipe to a rotary part of a variety of machines, and drain the fluid from the rotary part to the stationary pipe while completely sealing the fluid. For example, the rotary union may be used to supply a heat medium, such as steam, hot water or hot oil, or a refrigerant, such as water, ammonia or Freon, to a rotary part, such as a rotary drum or a rotary cylinder, thus heating or cooling the rotary part.

Furthermore, the rotary union may be used to supply an actuation medium, such as compressed air or actuation oil, to a fluid- actuated rotary device, such as a clutch or a brake.

FIG. 8 shows the construction of a conventional rotary union.

As shown in the drawing, the rotary union comprises a housing 1'that defines an appearance of the rotary union, with a rotary pipe 2'installed in the housing 1'to be rotated. A siphon pipe mounting unit 3'is mounted to an inner surface of an inside end of the rotary pipe 2'while being sealed by both a grand cover 5'and a grand packing 4'. An elbow 6'is mounted to an end of the

housing 1'to communicate with a fluid path of a siphon pipe (not shown) that is installed in the siphon pipe mounting unit 3'. The rotary union further comprises a mechanical seal 7'that is installed at a junction part between the rotary pipe 2'and the housing 1'to seal the junction part, and thereby, prevent a leakage of a fluid that flows in the rotary pipe 2'.

The housing 1'is opened at front and rear ends thereof, with a bore defined in the housing 1'and a fluid inlet la'formed on an intermediate portion of the housing 1'to introduce the fluid into the housing 1'. Both a cover lb'and a stopper lc'are mounted to the opened rear end of the housing 1'from which an extension part of the rotary pipe 2'extends outward. First and second caps ld'and le'are placed in the bore of the housing 1'.

The rotary pipe 2'is installed in the housing 1'to be rotated. The rotary pipe 2'is also coupled to a rotary drum or a rotary cylinder of a variety of rotary machines at an outside end thereof, so that the rotary pipe 2'is rotated by a rotating motion of the rotary drum or the rotary cylinder. A sealing surface 2a' is provided around an outer surface of an inside part of the rotary pipe 2'while extending outward in radial directions. Furthermore, a plurality of fluid inlets 2b'are formed around a sidewall of the rotary pipe 2'at positions to correspond to the fluid inlet la'of the housing 1'.

The siphon pipe mounting unit 3'is mounted to the inside end of the rotary pipe 2'while being sealed by both the grand packing 4'and the grand cover 5'. The siphon pipe (not shown) is

installed in the siphon pipe mounting unit 3'to drain the fluid from the rotary drum or the rotary cylinder of a variety of machines to an outside of the housing.

The elbow 6'is mounted to the front end of the housing 1' to communicate with an interior of the siphon pipe mounting unit 3'. Thus, the elbow 6'discharges the fluid, which has been drawn by the siphon pipe (not shown) that is installed in the siphon pipe mounting unit 3', to the outside of the housing.

The mechanical seal 7'has been installed on a variety of rotary shafts, which rotate at high speeds under high temperatures and high pressures, in an effort to prevent a leakage of fluids, in the related art. The mechanical seal 7'comprises a first packing 7a', a second packing 7b', and an elastic member 7c'.

The first packing 7a'is made of a carbon material, and is placed to face the sealing surface 2a'of the rotary pipe 2'.

Thus, the first packing 7a'is rotated along with the rotary pipe 2'to come into rotary contact with the first cap ld'of the housing 1'.

The second packing 7b'is made of a carbon material, and is placed between the sealing surface 2a'of the rotary pipe 2'and the second cap le'of the housing 1'. The second packing 7b'thus comes into rotary contact with the sealing surface 2a'of the rotary pipe 2'in response to a rotating motion of the rotary pipe 2'.

The elastic member 7c'is shaped as a coil spring, and is placed between the sealing surface 2a'of the rotary pipe 2'and

the first packing 7a', thus applying the elasticity thereof to both the rotary contact part of the first packing 7a'and the rotary contact part of the second packing 7b'in response to a rotating motion of the rotary pipe 2'. Therefore, a desired sealing effect is accomplished at the rotary contact parts of the packings 7a'and 7b'.

Accordingly, the mechanical seal 7'prevents a leakage of the fluid flowing in the rotary pipe 2'by the elastic sealing functions provided between the first packing 7a'and the first cap ld'and between the second packing 7b'and the second cap le'.

Due to the above-mentioned construction with both the rotary pipe 2'and the siphon pipe, the rotary union supplies a fluid from a stationary pipe to a rotary part of a variety of machines, and drains the fluid from the rotary part to the stationary pipe.

However, the conventional rotary union is problematic in that, because the first cap ld'of the housing 1'and the sealing surface 2a'of the rotary pipe 2'that are respectively in rotary contact with the packings 7a'and 7b'are made of metal materials, severe abrasion results from the contact between the carbon materials and the metal materials. Thus, the sealing effect of the rotary union is reduced to cause a reduction in the operational reliability thereof. Furthermore, the expected life span of the rotary union is reduced, and thereby, the rotary union must be frequently repaired or changed with a new one, so that the economic efficiency of the conventional rotary union is reduced.

Furthermore, the mechanical seal in the conventional rotary

union provides a sealing function by the elastic member that elastically biases the first and second packings. However, when at least one of the rotary part and the stationary part is in a vacuum state in the interior thereof, the sealed state of a remaining one of the two parts is released regardless of the elastic biasing force of the elastic member, thus allowing for a leakage of the fluid. Furthermore, when the rotary union has been used for lengthy periods, the elasticity of the elastic member is lowered to reduce the sealing function provided by the mechanical seal.

In addition, the construction of the conventional mechanical seal is complex, and thus, it is very difficult to manufacture the mechanical seal, or to assemble or repair the rotary union.

Furthermore, an 0-ring 4b'made of rubber cannot effectively resist chemicals, so that the use of the conventional rotary union is limited when requiring to use it under severe operational conditions at a high speed, high temperature and high pressure.

Particularly, because the conventional mechanical seal provides the sealing effect to prevent a leakage of the fluid by a formation of an oil layer caused by surface contact, the lubrication oil must be supplied to the mechanical seal. Thus, the mechanical seal must be provided with a lubrication oil supply system that supplies the lubrication oil to the seal.

However, the supply of the lubrication oil to the mechanical seal reduces the yield of products in semiconductor equipments requiring very high accuracy. Furthermore, the lubrication oil may infiltrate into the semiconductor equipments. Thus, the rotary

union having the conventional mechanical seal is problematic in that the life span thereof is too short due to the above-mentioned problems caused by the lubrication oil.

Furthermore, the conventional sealing method of providing a sealing effect caused by the surface contact cannot prevent infiltration of slurry, including ultrafine particles, into the seal. Thus, the expected life span of the rotary union is further reduced.

Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a rotary union which comprises a feed shaft, an intermediate housing and an outer housing, wherein the shaft is constructed as a stationary shaft, while the intermediate housing is constructed to rotate within the outer housing, and which enhances sealing effects between the feed shaft, the intermediate housing and the outer housing, thus preventing a leakage of a fluid in a pressurized or vacuum state, and which has a simple sealing structure to cause easy manufacture, maintenance and repairing of the rotary union, and which has a minimum size to reduce the volume of a space in which the rotary union is installed.

Another object of the present invention is to provide a rotary union in which a sealing unit is in linear contact with a

rotary object, thus minimizing the friction at a junction between the sealing unit and the rotary object and thereby removing the necessity to supply lubrication oil to the junction.

In order to accomplish the above objects, the present invention provides a rotary union mounted at an end thereof to a rotary part (100) and coupled at an opposite end thereof to a fluid supply unit (200) connected to a fluid supply source, the rotary union comprising: an outer housing (2) having a bore (22) therein, with a plurality of fluid outlets (24) formed on a sidewall of the outer housing to communicate with the bore (22); an intermediate housing (4) having a shaft hole (42) therein, and inserted into the bore (22) of the outer housing (2) to be rotated, the intermediate housing being mounted at an end thereof to the rotary part (100) and at an opposite end thereof to a drive unit (300); a feed shaft (6) having a plurality of fluid channels (62) therein, and inserted into the shaft hole (42) of the intermediate housing (4), the feed shaft being mounted at an end thereof to the fluid supply unit (200); and a first sealing unit and a second sealing unit to prevent a leakage of a fluid, the first sealing unit being interposed between the outer housing (2) and the intermediate housing (4), and the second sealing unit being interposed between the intermediate housing (4) and the feed shaft (6).

Brief Description of the Drawings The above and other objects, features and other advantages

of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which : Fig. 1 is an exploded perspective view showing the construction of a rotary union according to the present invention ; Fig. 2 is a side sectional view showing an embodiment of the rotary union according to the present invention ; Fig. 3 is a front sectional view of an outer housing included in the present invention; Fig. 4 is a front sectional view of an intermediate housing included in the present invention; Fig. 5 is a front sectional view of a feed shaft included in the present invention; Figs. 6a and 6b are front sectional views of first and second fixing rings included in the present invention ; Figs. 7a and 7b are partially broken perspective views of first and second sealing members included in the present invention; and Fig. 8 is a sectional view of a conventional rotary union.

*Description of the elements in the drawings* 2: outer housing 4: intermediate housing 6: feed shaft 22: bore 24: fluid outlet 26: third bearing 28: second bearing 42 : shaft hole 43: first sealing member 44: coolant outlet path

45: first fixing ring 47: first support ring 48 : first bearing 62: fluid channel 63 : fifth bearing 64 : coolant inlet path 65: second fixing ring 66: second sealing member 67: second support ring 70a, 70b : support ring 440,650 : path hole 450, 650: through hole 430, 660 : seal ring 431,661 : sealing edge Best Mode for Carrying Out the Invention Herein below, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the accompanying drawings, Fig. 1 is an exploded perspective view showing the construction of a rotary union according to the present invention. Fig. 2 is a side sectional view showing an embodiment of the rotary union according to the present invention. Fig. 3 is a front sectional view of an outer housing included in the present invention. Fig. 4 is a front sectional view of an intermediate housing included in the present invention. Fig. 5 is a front sectional view of a feed shaft included in the present invention. Figs. 6a and 6b are front sectional views of first and second fixing rings included in the present invention.

Figs. 7a and 7b are partially broken perspective views of first and second sealing members included in the present invention.

As shown in the drawings, the rotary union according to the

present invention comprises an outer housing 2, an intermediate housing 4 inserted in the outer housing 2, and a feed shaft 6 inserted in the intermediate housing 4. In the rotary union, the intermediate housing 4 is constructed to rotate in the outer housing 2. To enhance a sealing effect of the rotary union, a sealing unit to prevent a leakage of a fluid is provided in the rotary union. The sealing unit comprises a plurality of first sealing members 43 that are placed around an inner surface of the outer housing 2 to be in contact with the intermediate housing 4, and a plurality of second sealing members 66 that are placed around an inner surface of the intermediate housing 4 to be in contact with the feed shaft 6.

The outer housing 2 is a cylindrical body that has a bore 22 of a predetermined size to receive the intermediate housing 4 therein. A plurality of fluid outlets 24 are formed on a sidewall of the outer housing 2 in radial directions perpendicular to an axis of the bore 22. Furthermore, the plurality of the first sealing members 43, a second bearing 28 and a third bearing 26 are placed around the inner surface of the outer housing 2 to be in contact with an outer surface of the intermediate housing 4.

In the embodiment of the present invention, eight fluid outlets 24 are formed on the sidewall of the outer housing 2 as shown in Fig. 3. To prevent a deformation of the outer housing 2 caused by a reduction in the strength of the outer housing, the fluid outlets 24 are arranged in a zigzag pattern.

The intermediate housing 4 is a cylindrical body that has a shaft hole 42 of a predetermined size to receive the feed shaft 6

therein. A plurality of coolant outlet paths 44 is formed in a sidewall of the intermediate housing 4 in lengthwise directions. A plurality of path holes 440 are formed through the sidewall of the intermediate housing 4 at positions between the plurality of coolant outlet paths 44. Thus, the shaft hole 42 communicates with an outside of the outer surface of the intermediate housing 4 through the path holes 440. The intermediate housing 4 passes through a rotary part 100 at an end thereof with a first bearing 48 interposed between the intermediate housing 4 and the rotary part 100. The intermediate housing 4 is also inserted into the bore 22 of the outer housing 2, while a drive unit 300 is mounted to a tapped slot 41 formed on the opposite end of the intermediate housing 4.

In the embodiment of the present invention, as shown in Fig.

4, twelve coolant outlet paths 44 are formed in the sidewall of the intermediate housing 4 in the lengthwise directions, while twelve path holes 440 are formed through the sidewall of the intermediate housing 4 in radial directions at positions between the plurality of coolant outlet paths 44.

The feed shaft 6 is a longitudinal body of a predetermined length which is inserted in the shaft hole 42 of the intermediate housing 4. To prevent an undesired increase in the temperature of the shaft 6, a coolant inlet path 64 is formed through a center of the shaft 6 in a lengthwise direction. Furthermore, a plurality of fluid channels 62 having different lengths are formed in a sidewall of the feed shaft 6 in lengthwise directions while being spaced apart from each other at regular angular intervals. The plurality of

second sealing members 66, a fourth bearing 61 and a fifth bearing 63 are placed around and end of the outer surface of the feed shaft 6. The drive unit 300 is supported around the opposite end of the feed shaft 6 with a bearing interposed between the drive unit 300 and the shaft 6. Furthermore, a plurality of fluid inlets 640 is formed on the outer surface of the feed shaft 6 to communicate with inside ends of the fluid channels 62.

In the rotary union, water or another coolant flows through the coolant inlet path 64, thus cooling the heated feed shaft that rotates at a high speed and other parts around the feed shaft.

The sealing unit comprises the plurality of first sealing members 43 and a plurality of first fixing rings 45 which are alternately placed around the inner surface of the outer housing 2 at positions between the second and third bearings 28 and 26. The sealing unit further comprises the plurality of second sealing members 66 and a plurality of second fixing rings 65 which are alternately placed around the outer surface of the feed shaft 6 at positions between the fourth and fifth bearings 61 and 63.

As shown in the drawings, each of the first sealing members 43 and the second sealing members 66 is provided along each of both side surfaces thereof with an annular groove 433,663 of a predetermined depth. Reinforcing members 432 and 662 are inserted into the annular grooves 433 and 663, respectively. Two sealing edges 431,661 are formed along opposite outside edges of an inner surface of each first sealing member 43 or of an outer surface of each second sealing member 66.

In the embodiment of the present invention, two seal rings 430, 660 are placed to face each other, thus providing a first sealing member 43 or a second sealing member 66 in which the two sealing edges 431,661 are opposite to each other. The plurality of annular first fixing rings 45 are interposed between the first sealing members, while the plurality of annular second fixing rings 65 are interposed between the second sealing members.

In the above state, the ridges of the sealing edges 431 of each first sealing member 43 are in contact with the outer surface of the intermediate housing 4. In the meantime, the ridges of the sealing edges 661 of each second sealing member 66 are in contact with the inner surface of the intermediate housing 4. Therefore, desired sealing effects are preferably provided by linear contact between the sealing edges and the intermediate housing.

The first sealing members and the second sealing members may be changed in shapes thereof as shown in Figs. 7a and 7b.

In a detailed description, a curved lip 431a may be formed along an inner surface of an annular seal ring 430a of a first sealing member 43a, while a curved lip 661a may be formed along an outer surface of an annular seal ring 660b of a second sealing member 66b.

The fixing rings support the sealing members 43 and 66 that are respectively placed around the outer surfaces of the intermediate housing 4 and the feed shaft 6. The fixing rings also allow for a feeding of the fluid, and comprise the first fixing rings 45 that are placed around the outer surface of the

intermediate housing 4 and the second fixing rings 65 that are placed around the feed shaft 6.

Furthermore, as shown in Figs. 6a and 6b, each of the first and second fixing rings 45 and 65 is provided with a plurality of through holes 450,650. Thus, the fluid, which has been introduced into the rotary union through the plurality of fluid inlets 640 of the feed shaft 6, flows to the plurality of fluid outlets 24 of the outer housing 2 through the through holes 450 and 650, prior to being discharged to the outside of the rotary union.

In the embodiment of the present invention, six through holes 450 are formed in each first fixing ring 45 at regular angular intervals, while four through holes 650 are formed in each second fixing ring 65 at regular angular intervals.

Therefore, the feed shaft 6, the rotary intermediate housing 4, the outer housing 2, and the plurality of first and second fixing rings 45 and 65 that are interposed between them provide a fluid communication structure which is defined by the fluid inlets 640, the through holes 450 and 650, the path holes 440, and the fluid outlets 24. Thus, the fluid, which has been introduced into the rotary union through the fluid channels 62 of the feed shaft 6, can be discharged to the outside of the rotary union through the fluid outlets 24 of the outer housing 2.

In other words, during a rotation of the intermediate housing 4, the path holes 440 of the intermediate housing 4 intermittently communicate with the through holes 450 and 650 of the first and second fixing rings 45 and 65. Thus, the fluid under a predetermined

pressure flows to the outer housing 2 through the path holes and the through holes.

The assembling process and the operation of the above- mentioned rotary union according to the present invention is as follows.

First, the plurality of first sealing members 43 and the plurality of first fixing rings 45 are alternately placed around the inner surface of the outer housing 2, and thereafter, the second and third bearings 28 and 26 are placed in the front and rear ends of the outer housing 2.

In the above case, the through holes 450 of the first fixing rings 45 must be aligned with the fluid outlets 24, respectively.

Furthermore, the plurality of second sealing members 66 and the plurality of second fixing rings 65 are alternately placed around the outer surface of the feed shaft 6, and thereafter, the fourth and fifth bearings 61 and 63 are placed around the front and rear ends of the feed shaft 6.

In the above case, the through holes 650 of the second fixing rings 65 must be aligned with the fluid inlets 640, respectively.

Thereafter, the intermediate housing 4 is inserted into the bore 22 of the outer housing 2.

Thereafter, the feed shaft 6 is inserted into the shaft hole 42 of the intermediate housing 4. In the above case, after the fluid inlets 640 are aligned with the through holes 650 of the second fixing rings 65, respectively, a first support ring 47 is fitted into the front end of the intermediate housing 4. Furthermore, a

second support ring 67 is fitted into the rear end of the intermediate housing 4, so that the second support ring 67 comes into contact with the outer surface of the feed shaft 6.

After the rotary union A is completely assembled, the rotary part 100 is mounted to the front end of the intermediate housing 4, while the drive unit 300 is mounted to the rear end of the intermediate housing 4. Furthermore, a fluid supply unit 200 that is connected to a fluid supply source is coupled to the rear end of the feed shaft 6 such that the fluid supply unit 200 communicates with both the fluid channels 62 and the coolant inlet path 64. A coolant drain unit (not shown) is coupled to the ends of the coolant outlet paths 44 formed in the intermediate housing 4.

Thus, the feed shaft 6, the intermediate housing 4 and the outer housing 2 rotate along with the rotary part 100 by the drive unit 300.

In the above state, the feed shaft 6, the intermediate housing 4 and the outer housing 2 rotate at different high speeds. During the above-mentioned rotation, the fluid inlets 640, the through holes 450 and 650, the path holes 440, and the fluid outlets 24 are frequently and intermittently aligned with each other, so that the inlet fluid is discharged to the outside-of the rotary union.

In a detailed description, when the drive unit 300 is operated, the intermediate housing 4 is first rotated, so that the feed shaft 6 and the outer housing 2 are secondarily rotated by the rotation of the intermediate housing 4. During such a rotation, the fluid inlets 640, the through holes 450 and 650, the path holes 440,

and the fluid outlets 24 are intermittently aligned with each other, and at that time, the fluid inlets 640, the through holes 450 and 650, the path holes 440, and the fluid outlets 24 communicate with each other. Thus, the inlet fluid can be discharged to the outside of the rotary union.

In the above state, the inlet fluid passes through the through holes 650 of the second fixing rings 65, and thereafter, passes through the path holes 440 of the intermediate housing 4 when the path holes 440 are aligned with the through holes 650. Thereafter, the fluid passes through the through holes 450 of the first fixing rings 45, and is discharged to the outside of the rotary union through the fluid outlets 24 of the outer housing 2.

In the meantime, the coolant, which has been supplied from the rear end of the feed shaft 6, sequentially passes through the coolant inlet path 64 and the coolant outlet paths 44 of the intermediate housing 4, and is discharged to the outside through the rear end of the intermediate housing 4.

In the above-mentioned process, the fluid is completely sealed by both the first sealing members 43 and the second sealing members 66.

In other words, because each of the first and second sealing members 43 and 66 is formed by two seal rings which are placed such that two sealing edges 431,661 thereof are opposite to each other, the sealing unit provides a double sealing structure to completely seal the fluid. Thus, the sealing effect of the rotary union is enhanced.

Furthermore, in the first and second sealing members 43 and 66 of the rotary union according to the present invention, the sealing edges 431 and 661 are in linear contact with the outer surface and the inner surface of the intermediate housing, respectively. Thus, the friction at the junctions between the sealing members and the intermediate housing is minimized, and thereby, the rotary union of the present invention is free from the necessity to supply lubrication oil to the junctions.

Industrial Applicability As described above, the present invention provides a rotary union which enhances sealing functions between a feed shaft, an intermediate housing and an outer housing, thus preventing a leakage of a fluid. The rotary union also has a simple sealing structure to cause easy manufacture, maintenance and repairing thereof, and has a minimum size to reduce the volume of a space in which the rotary union is installed. Furthermore, each of the sealing members included in the rotary union is in linear contact with a rotary object, thus minimizing the friction at junctions between the sealing members and the rotary object and thereby removing the necessity to supply lubrication oil to the junctions.

Thus, the simpleness and compactness of the construction of the rotary union is achieved.