Patent Application
20060192343
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-051432, filed Feb. 25, 2005, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The invention relates to a liquid-sealing shaft seal apparatus for a rotary electrical machine using liquid, such as lubrication oil or seal oil, and to a rotary electrical machine using the shaft seal apparatus.
2. Description of the Related Art
In general, large rotary electrical machines employ slider bearings using oil as a lubricant. In order to achieve the high efficiency, hydrogen-cooled rotary electrical machines employ oil seals using sealing oil to seal hydrogen gas for cooling the interior of the machine inside of the rotary electrical machine. Generally, labyrinth seals are used to prevent lubrication oil, seal oil, or the like from leaking to the interior or exterior of a rotary electrical machine. In this case, it is generally known that, as an inherent structural nature of the labyrinth seal, a relatively large gap exists between the seal and a rotation shaft of the rotary electrical machine, the fluid may leak responsively following, for example, liquid state variations. To minimize such leakage, measures are taken such that, for example, labyrinth seals are provided in multiple stages, or a labyrinth seal is arranged in a position sufficiently spaced away from a liquid source. However, according to such measures, the overall size of the rotary electrical machine has to be increased, and also the seal performance is not sufficient, so that it is difficult to prevent leakage of the fluid.
In recent years, in order to solve these problems, techniques are known that use brush seals to improve seal performance (for example, refer to Jpn. Pat. Appln. KOKAI Publication Nos. 2001-90842, 2001-295609, and 2002-303371. However, the techniques disclosed in Jpn. Pat. Appln. KOKAI Publication Nos. 2001-90842 and 2001-295609 are not intended to seal liquid but intended to seal gases.
In general, a conventional liquid-sealing shaft seal apparatus of a rotary electrical machine, which uses a brush seal, has a structure shown in
In any of Jpn. Pat. Appln. KOKAI Publication Nos. 2001-90842, 2001-295609, and 2002-303371, the structure of the brush seal apparatus itself is not described in detail, however, it is assumed that the shaft seal apparatus uses such a conventional brush seal of the type as described with reference to
In addition, there is a rotary electrical machine of the type that has different liquids and that uses a shaft seal apparatus to avoid mixture of the liquids. For example, in the construction shown in
According to one aspect of the present invention, there is provided a liquid-sealing shaft seal apparatus comprising: a rotation shaft; brush seals arranged in such a manner as to contact and surround the rotation shaft; and a brush holder which holds the brush seals, wherein more than one line of brush seals are arranged in the axial direction of the rotation shaft through a cavity; and the brush holder is provided with a liquid returning pass to return a liquid having leaked through the brush seals into the cavity to the side of an atmosphere in which a liquid is present as a sealing target.
According to another aspect of the present invention, there is provided a liquid-sealing shaft seal apparatus comprising: a rotation shaft; brush seals arranged in such a manner as to contact and surround the rotation shaft; and a brush holder which holds the brush seals, wherein more than one line of brush seals are arranged in an axial direction of the rotation shaft through a cavity, and a pressure in the cavity is higher than a pressure on the side of an atmosphere in which a liquid is present as a sealing target.
Embodiments of the present invention will be described herebelow with reference to the accompanying drawings.
Referring to
In space portions on the side of a bore of the brush holder 3 in the axial direction, two lines of brush seals spaced away from each other via a cavity 10 to be described later are stored. Namely, there are stored two-line brush seals formed of a brush seal 4a on the side of the liquid atmosphere S1 and a brush seal 4b on the side of the non-liquid atmosphere S2. The brush seals 4a, 4b each is formed in the manner that a brush 5 is clamped by a brush clamp 6. The brush seals 4a, 4b each is formed such that multiple brush segments circumferentially split are combined into an annular state as an array, and that two arrays are arranged by shifting circumferentially split planes of the brush segments.
For example, with reference to
In
Numeral 10 denotes a cavity as described above, which is provided by the spacer 8 between the brush seals 4a and 4b axially provided in the two stages. The cavity 10 is a space having an external diameter larger than that of the sealing plane which can reduce the flow of gas in the periphery of the rotation shaft 1 generated with the rotation of the rotation shaft 1. Numeral 11 denotes a through-hole provided on the side of the external diameter of the brush holder 3. The through-hole 11 is configured to allow communication of pressure between the axial atmosphere spaces S1 and S2 of the rotary electrical machine separated by the brush holder 3, thereby to keep the pressures on the both outer sides of the brush seals 4a, 4b equal. Numeral 12 is a liquid returning pass that continuously extends through the spacer 8, the brush holder 3, and the holding plate 9. The liquid returning pass 12 is thus formed to return liquid QL, which has leaked into the cavity 10 from the liquid atmosphere space S1, to the liquid atmosphere space S1. Exterior portions of an axial-end bore portion 3a of the brush holder 3 and a bore portion 9a of the holding plate 9, respectively, are largely chamfered to form an inclined plane. This prevents liquid from accumulating in gaps between the respective exterior portions and the rotation shaft 1, but falls down under gravity.
Operation of the present embodiment will be described herebelow.
While the liquid atmosphere space S1 in the interior of the frame 2 of the rotary electrical machine enters the state in which the liquid is dispersed by the rotation of the rotation shaft 1, a large amount of dispersing liquid is sealed by the brush seal 4 on the liquid atmosphere S1. However, part of the dispersing liquid passes through, for example, gaps between the brushes 5 of the brush seal 4a and between the brushes 5 and the rotation shaft 1 and leaks as a leakage liquid QL into the cavity 10. In this event, the resin sheet packing 7 is deformed by the holding plate 9 being press tightened against the brush holder 3, thereby to seal gaps with the brush holder 3, the holding plate 9, and the brush clamp 6. Consequently, liquid leakage from a gap between the rear face of the brush seal 4a and the brush holder 3 can be prevented. In addition, since the initial gap with the rotation shaft 1 is set to zero, initial abrasion is caused when the rotation shaft 1 rotates. Thereby, the gaps with the rotation shaft 1 and the resin sheet packing 7 are reduced to minimum gaps in size set in consideration factors including, for example, whirling resulting from eccentricity and the like of the rotation shaft 1, and the area of contact between the liquid and the brush 5 of the brush seal 4a is minimized. Therefore, since the liquid is permeated into the brush 5 of the brush seal 4a, the amount of the liquid QL leaking into the cavity 10 is significantly reduced. Moreover, since the cavity 10 exists, the leakage liquid QL is not influence by the rotation of the rotation shaft 1, but falls in the gravitation direction and then flows into the liquid returning pass 12, whereby the liquid QL is returned into the liquid atmosphere space S1.
In addition, the liquid atmosphere space S1 and the non-liquid atmosphere space S2 are in communication with each other through the through-hole 11, so that the pressure is the same in the spaces S1 and S2. Accordingly, no differential pressure is applied to the brush seal 4a, 4b, so that the amount of leakage liquid QL is not increased. Further, since the axial-end bore portion 3a of the brush holder 3 and the bore portion 9a of the holding plate 9 are largely chamfered to form the inclined plane, the liquid does not accumulates in the gaps between the respective chamfered portions and the rotation shaft 1. Consequently, the amount of liquid possibly in contact with the brush 5 of the brush seal 4a can be reduced.
As described above, according to the present embodiment, it is possible to reduce the amount of leakage liquid QL leaking through the brush seal 4a through the resin sheet packing 7, the axial-end bore portion 3a of the brush holder 3, the bore portion 9a of the holding plate 9, and the through-hole 11. Further, with the cavity 10 being arranged, the leakage liquid QL having leaked through the brush seal 4a on the side of the liquid atmosphere is prevented from dispersing in the cavity 10, but is guided to fall along the gravitation direction. Thereby, the liquid QL can be returned to the liquid atmosphere space S1 through the liquid returning pass 12. Consequently, the amount of liquid leaking into the non-liquid atmosphere space S2 through the brush seal 4b can be significantly reduced.
Referring to
Operation of the present embodiment will be described herebelow.
The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical machine, which is constructed as described above, operates as follows. While the liquid QL in the liquid atmosphere Q is dispersed in the liquid atmosphere space Q in conjunction with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4c on the side of liquid atmosphere Q. In this case, as in the first embodiment, the amount of the leakage liquid QL leaking from the brush seal 4c on the side of the liquid atmosphere Q is reduced to be smaller than in the conventional techniques. This is implemented by the functions of the resin sheet packings 7, the shape of the brush-holder axial-end bore portion 3a, and the structure including the through-hole 11. In addition, by virtue of the cavity 10a, the leakage liquid QL having leaked into the cavity 10a does not disperse in the cavity 10a, but is guided to flow down under gravity, whereby the liquid is returned into the liquid atmosphere space Q through the returning pass 12a for the liquid QL. Consequently, the amount of leakage liquid QL leaking through the brush seal 4e to the side of the cavity 10b is significantly reduced.
On the other hand, while the liquid on the side of the liquid atmosphere R is dispersed in the liquid atmosphere space R in conjunction with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4d on the side of liquid atmosphere R. In this case, however, similarly as in the case of the brush seal 4c on the side of the liquid atmosphere Q, the amount of leakage liquid RL leaking from the brush seal 4d on the side of the liquid atmosphere R is smaller than in the conventional techniques. This is implemented by the functions of the resin sheet packings 7, the shape of the bore portion 9a of the holding plate 9, and the structure including the through-hole 11. In addition, by virtue of the cavity 10b, the leakage liquid RL having leaked into the cavity 10b does not disperse in the cavity 10a, but is guided to flow down under gravity, whereby the liquid is returned into the liquid atmosphere space R through the returning pass 12b for the liquid RL. Consequently, the amount of leakage liquid RL leaking through the brush seal 4e to the side of the cavity 10b is significantly reduced.
As described above, according to the present embodiment, the respective amounts of leakage liquid leaking through the brush seal 4e can be reduced. This is implemented by the functions of the resin sheet packings 7, the shapes of the axial-end bore portion 3a of the brush holder 3 and the bore portion 9a of the holding plate 9, and the structure including the through-hole 11. In addition, by virtue of cavities 10a, 10b, the respective leakage liquids QL, RL having leaked through the brush seals 4c, 4d on the liquid atmosphere do not disperse in the cavities 10a, 10b, but flows down in the gravitation direction, whereby the liquids can be returned into the liquid atmosphere spaces Q, R through the liquid returning passes 12a, 12b. Consequently, the amount of leakage liquid leaking through the brush seal 4e to the other liquid atmosphere space, and the amount of mixture between the liquids Q and R can be significantly reduced.
Referring to
Operation of the present embodiment will be described herebelow.
The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical machine, which is constructed as described above, operates as follows. While the liquid in the liquid atmosphere Q is dispersed in the liquid atmosphere space Q in conjunction with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4c on the side of liquid atmosphere Q. In this case, as in the first embodiment, the amount of the leakage liquid QL leaking from the brush seal 4c on the side of the liquid atmosphere Q into the cavity 10a is reduced to be smaller than in the conventional techniques by the functions of the resin sheet packings 7. In addition, when a pressure higher than that in the liquid atmosphere space Q is applied to the cavity 10a through the cavity through-hole 13 from the outside of the rotary electrical machine, a pressure in the reverse direction with respect to the leakage direction of the leakage liquid QL is exerted on the brush seal 4c. Thereby, the leakage liquid QL having leaked through, for example, the gap with the brush 5 constituting the brush seal 4c and the gap between the brush 5 and the rotation shaft 1 is returned to the liquid atmosphere space Q. Consequently, the leakage liquid QL is significantly reduced in amount, and does not accumulate in the cavity 10a.
On the other hand, while the liquid in the liquid atmosphere R disperses in the liquid atmosphere space R in conjunction with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4d on the side of liquid atmosphere R. In this case, as in the first embodiment, the amount of leakage liquid RL leaking from the brush seal 4d on the side of the liquid atmosphere R into the cavity 10b is reduced to be smaller than in the conventional techniques by the functions of the resin sheet packings 7. In addition, when a pressure higher than that in the liquid atmosphere space R is applied to the cavity 10b through the cavity through-hole 14 from the outside of the rotary electrical machine, a pressure in the reverse direction with respect to the leakage direction of the leakage liquid RL is exerted on the brush seal 4d. Thereby, the leakage liquid RL having leaked through, for example, the gap with the brush 5 constituting the brush seal 4d and the gap between the brush 5 and the rotation shaft 1 is returned to the liquid atmosphere space R. Consequently, the leakage liquid RL is significantly reduced in amount, and does not accumulate in the cavity 10b.
In a general rotary electrical machine, a cooling fan is provided for intra-machine ventilation, so that the intra-machine pressure is negative with respect to the atmospheric pressure. In this case, through-holes corresponding to the cavity through-holes 13 and 14 are opened to the atmosphere, so that the pressure is increased, whereby effects equivalent to the case of pressurization can be obtained.
As described above, according to the present embodiment, in addition to the effects of the resin sheet packings 7, the cavity through-holes 13 and 14 are either applied with pressure or opened to the atmosphere. In this case, the brush seals 4c and 4d, respectively, are applied with pressure differences in the reverse direction with respect the leakage directions of the leakage liquids QL and RL. Consequently, the respective liquids do not leak through the brush seal 4e into the cavities 10a and 10b, nor do the respective liquids mix into one another. Further, when the cavity through-holes 13 and 14 are opened to the atmosphere, a compressor is not necessary, thereby simplifying the construction and reducing the cost thereof.
Referring to
Operation of the present embodiment will be described herebelow.
The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical machine, which is constructed as described above, operates as follows. While the liquid in the liquid atmosphere S1 is dispersed in the liquid atmosphere space S1 in conjunction with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4a on the side of liquid atmosphere S1. In this case, as in the first embodiment, the amount of leakage liquid leaking from the brush seal 4a on the side of the liquid atmosphere S1 into the cavity 10 is reduced to be smaller than in the conventional techniques by the functions of the resin sheet packings 7 and the shape of the bore portion 9a of the holding plate 9. In addition, most of the liquid having leaked to the cavity 10 is captured by the short brush 16, and permeates into the short brush 16 through capillarity or capillary action. The short brush 16 has a length not contacting the rotation shaft 1. The liquid permeated in the short brush 16 is directed under gravity to flow downward along the short brush clamp 17, and then is returned to the liquid atmosphere space S1 through the liquid returning pass 12 from the holes H in the radial direction provided in the short brush clamp 17. Consequently, the liquid leaking through the brush seal 4b into the non-liquid atmosphere space S2 is significantly reduced.
As described above, according to the present embodiment, in addition to the effects of the resin sheet packings 7 and the shape of the bore portion 9a of the holding plate 9, even a small amount of liquid having leaked through the brush seal 4a is securely trapped by the short brush seal 15 provided in the cavity 10, and then is returned to the liquid atmosphere space S1 by using the liquid returning pass 12. Consequently, liquid sealing performance in the case of a rotary electrical machine containing the liquid is significantly improved. Further, even mist-state liquid can be securely captured through the capillary action of the short brush 16. Consequently, advantages can be obtained in that the size of the cavity 10 can be reduced, and hence the overall size of the brush seal apparatus can be reduced.
Referring to
Operation of the present embodiment will be described herebelow.
The present embodiment of the liquid-sealing shaft seal apparatus in the rotary electrical machine, which is constructed as described above, operates as follows. While the liquid in the liquid atmosphere S1 is dispersed in the liquid atmosphere space S1 in conjunction with the rotation of the rotation shaft 1, the gap is sealed by the brush seal 4a on the side of liquid atmosphere S1. In this case, as in the first embodiment, the amount of the leakage liquid QL leaking from the brush seal 4a on the side of the liquid atmosphere S1 into the cavity 10 is reduced to be smaller than in the conventional techniques by the functions of the resin sheet packings 7 and the shape of the bore portion 9a of the holding plate 9. In addition, most of the liquid having leaked into the cavity 10 is captured by the porous spacer 18 arranged on the side of the external diameter of the cavity 10. The liquid thus captured is directed under gravity to flow downward through the interior of the porous spacer 18, and then is returned to the liquid atmosphere space S1 through the porous filler material 19 filled into the liquid returning pass 12 arranged below the cavity 10. Consequently, the amount of liquid leaking through the brush seal 4b into the non-liquid atmosphere space S2 is significantly reduced.
As described above, according to the present embodiment, in addition to the effects of the resin sheet packings 7 and the porous filler material 19, even a small amount of liquid having leaked through the brush seal 4a is securely captured by the porous spacer 18 formed of the porous material and provided in the cavity 10. Further, the liquid is guided to return to the liquid atmosphere space S1 through the porous filler material 19 filled in the liquid returning pass 12. Thereby, the amount of liquid leaking through the brush seal 4b into the non-liquid atmosphere space S2 is significantly reduced. Consequently, liquid sealing performance is significantly improved. Further, as in the fourth embodiment shown in
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-051432 | Feb 2005 | JP | national |
