JP4467896B2 - Pump shaft seal structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shaft seal structure of a pump having a mechanical seal in a pump for transporting fluid.
[0002]
[Prior art]
Conventionally, a gland packing, an oil seal, a mechanical seal, or the like is used for a shaft seal structure of a pump that transports fluid. In these shaft seal structures, in particular, in the mechanical seal, pressure water is continuously poured into the shaft seal portion to prevent the pumped fluid from entering the shaft seal portion. However, a pump with a non-water-injection mechanical seal that does not need to continuously inject pressure water into the shaft seal because a water supply source is required to continuously inject pressure water into the shaft seal. The shaft seal structure has been adopted. Furthermore, when a liquid with a high slurry concentration or an aerobic liquid is a fluid to be delivered, the shaft seal structure of the pump having only one non-water-injection mechanical seal (single mechanical seal) has this mechanical seal. Dry sliding is likely to occur between the stationary ring and the rotating ring. For this reason, the shaft seal structure of the pump provided with two mechanical seals (double mechanical seal) is employ | adopted.
[0003]
Some shaft seal structures of double mechanical seal pumps supply lubricating oil to the double mechanical seal for the purpose of stable operation of the shaft seal structure. As an example of such a shaft seal structure of a pump, there is one in which a lubricating oil tank and a lubricating oil chamber are formed in a pump (conventional example 1) (see, for example, Patent Document 1).
5 includes an impeller 112, a rotary shaft 114, a casing 116, a bearing box 132, a double mechanical seal 138, a lubricating oil chamber 170, and a lubricating oil tank 172.
[0004]
The casing 116 is supported by a bridge portion 133 extending from the bearing box 132, and a first mechanical shaft 138 is formed between the rotary shaft hole 120 </ b> C formed in the back wall 118 of the casing 116 and the rotary shaft 114. The second mechanical seal 140 and the second mechanical seal 146 are provided. The first mechanical seal 140 has a first fixed ring 142 and a first rotating ring 144 that are in sliding contact with each other, and a second fixed ring 148 and a second rotating ring 150 that are also in sliding contact with each other. Have There is a spring 166 between the first fixed ring 142 and the second fixed ring 148, and the spring 166 presses the first fixed ring 142 toward the first rotating ring 144, and the second fixed ring 148. Is pressed toward the second rotary ring 150.
[0005]
A lubricating oil chamber 170 is formed on the outer periphery of the spring 166, and the lubricating oil chamber 170 and the lubricating oil tank 172 are connected by a lubricating oil injection pipe 174 and a lubricating oil return pipe 176.
The rotary shaft hole 120 </ b> C and the rotary shaft 114 are sealed by a double mechanical seal 138, and when the fluid to be fed is discharged from the pump 110, leakage of the fluid to be fed out of the casing 116 is prevented.
[0006]
The lubricating oil chamber 170 is always filled with the lubricating oil supplied from the lubricating oil tank 172, and the lubricating oil is slidably contacted with the first fixed ring 142 and the first rotating ring 144, the second fixed ring. 148 and the second rotating ring 150 are supplied to the sliding contact portion and the spring 166, and the double mechanical seal 138 is prevented from sliding.
The rotary shaft 114 is open to the atmosphere between the second mechanical seal 146 and the bearing box 132, and the oil pan portion that is open to the air is provided between the back wall 118 below the rotary shaft 114 and the bearing box 132. 134 is formed.
[0007]
In addition, as an example of the shaft seal structure of another double mechanical seal pump that supplies lubricating oil to the mechanical seal, a lubricating oil chamber is formed between the casing and the bearing box, and the lubricating oil is enclosed in this lubricating oil chamber. There is one (conventional example 2) (see, for example, Patent Document 2).
A pump 210 of Conventional Example 2 shown in FIG. 6 includes an impeller 212, a rotating shaft 214, a casing 216, a bearing box 232, a double mechanical seal 238, and a lubricating oil chamber 270.
[0008]
An edge 219 of the back casing cover 218 on the back surface of the casing 216 is continuous with the bearing box 232, and a sealed lubricating oil chamber 270 is formed between the back casing cover 218 and the bearing box 232, and a large amount of oil is contained in the lubricating oil chamber 270. Lubricating oil can be retained.
A first mechanical seal 240 constituting a part of the double mechanical seal 238 is provided between the rotary shaft hole 220 </ b> C formed in the back casing cover 218 and the rotary shaft 214. The first mechanical seal 240 includes a first fixed ring 242 and a first rotating ring 244 that are in sliding contact with each other.
[0009]
A second mechanical seal 246 constituting a part of the double mechanical seal 238 is provided between the rotary shaft hole 220 </ b> B formed in the bearing box cover 233 of the bearing box 232 and the rotary shaft 214. The second mechanical seal 246 includes a second fixed ring 248 and a second rotating ring 250 that are in sliding contact with each other.
[0010]
Each of the first mechanical seal 240 and the second mechanical seal 246 has a spring 266, and each spring 266 presses the first fixed ring 242 toward the first rotating ring 244, and the second fixed. The ring 248 is pressed toward the second rotating ring 250.
The rotation shaft 214 and the rotation shaft hole 220 </ b> C are sealed by a first mechanical seal 240, and when the fluid to be fed is discharged from the pump 10, the fluid to be fed from the casing 216 into the lubricating oil chamber 270. Leakage is prevented.
[0011]
The rotation shaft 214 and the rotation shaft hole 220B are sealed by the second mechanical seal 246, and leakage of the lubricating oil from the lubricating oil chamber 270 into the bearing box 232 is prevented.
The lubricating oil in the lubricating oil chamber 270 is supplied to the sliding contact portion between the first fixed ring 242 and the first rotating ring 244 and the sliding contact portion between the second fixed ring 248 and the second rotating ring 250. Thus, dry sliding of the double mechanical seal 238 is prevented.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-182687 (FIG. 4)
[Patent Document 2]
Japanese Utility Model Publication No. 1-212295 (Fig. 4)
[0013]
[Problems to be solved by the invention]
However, in the shaft seal structure of the pump of Conventional Example 1, the capacity of the lubricating oil chamber 170 is small and the lubricating oil cannot be sufficiently stored. Accordingly, it is necessary to separately provide a large-capacity lubricating oil tank 172, a lubricating oil injection pipe 174, and a lubricating oil return pipe 176 to supply the lubricating oil to the lubricating oil chamber 170, and the structure of the pump 110 becomes large and complicated. To do. Therefore, in order to increase the capacity of the lubricating oil chamber, if the shaft seal structure of the pump as in Conventional Example 2 is used, if the fluid to be delivered leaks from the first mechanical seal 240 into the lubricating oil chamber 270, the fluid to be delivered Contaminated lubricating oil may leak from the second mechanical seal 246 into the bearing box 232 and damage the bearing 236.
[0014]
The present invention solves the above-described problems of the prior art, and in a pump having a shaft seal structure of a double mechanical seal, a sufficient amount of lubricating oil can be supplied to each mechanical seal without increasing the size of the pump. Another object of the present invention is to provide a shaft seal structure for a pump that can prevent the lubricating oil contaminated with the fluid to be fed into the bearing box from leaking out.
[0015]
[Means for Solving the Problems]
The present invention adopts the following configuration in order to solve the problem. That is, the shaft seal structure of the pump according to the first invention of the present invention is a pump comprising a casing, an impeller, a rotating shaft of the impeller, and a bearing box that supports the rotating shaft, and a back wall of the casing. A lubricating oil chamber and a sealed space, which are separated in the front and rear by a partition wall, are provided around a rotating shaft between the bearing box and a first mechanical unit between the back wall and the rotating shaft passing through the back wall. A second mechanical seal is provided between the seal and the partition wall and the rotating shaft passing through the partition wall, and lubricating oil is sealed in the lubricating oil chamber.
[0016]
According to the first invention , the volume of the lubricating oil chamber can be increased so that the entire amount of lubricating oil required to supply the first and second mechanical seals can be held in the lubricating oil chamber, and the lubricating oil tank is separately provided. do not need. In addition, there is a sealed space between the lubricating oil chamber and the bearing box. When the lubricating oil leaks from the lubricating oil chamber, the leaked lubricating oil accumulates in the sealed space and does not enter the bearing box directly. Therefore, even if the lubricating oil in the lubricating oil chamber is contaminated by the delivered fluid, the contaminated lubricating oil is prevented from reaching the bearings in the bearing box.
[0017]
The shaft seal structure of the pump according to the second invention is the shaft seal structure of the pump according to the first invention, wherein an auxiliary sealed space communicating with the sealed space is provided in at least one of the casing and the bearing box. .
According to the second invention , the lubricating oil leaked into the sealed space flows and accumulates in the auxiliary sealed space, and the leaked lubricating oil can be held in the sealed space and the auxiliary sealed space. The frequency and effort of the can be kept small.
[0018]
A shaft seal structure for a pump according to a third invention is the shaft seal structure for a pump according to the second invention, wherein an auxiliary sealed space is provided in the lower portion of the bearing box.
According to the third invention , by forming the auxiliary sealed space using the space below the bearing box, the capacity capable of holding the lubricating oil leaked from the lubricating oil chamber is further increased.
[0019]
A shaft seal structure for a pump according to a fourth invention is the shaft seal structure for a pump according to the first invention, and has a liquid leakage sensor in the sealed space.
According to the fourth invention , the leakage sensor can detect the lubricating oil accumulated in the sealed space, collect the lubricating oil leaked at an appropriate time, and replenish the lubricating oil chamber with the lubricating oil.
The shaft seal structure of the pump according to the fifth invention is the shaft seal structure of the pump according to the second invention or the third invention , and has a liquid leakage sensor in the auxiliary sealed space.
[0020]
According to the fifth aspect of the invention , the liquid leakage sensor detects the lubricating oil accumulated in the auxiliary sealed space, and the lubricating oil leaked at an appropriate time can be recovered.
Sealing structure of the pump according to a sixth aspect sealing structure of the pump according to any one of of from the first aspect fifth invention, the first mechanical on the inner peripheral side of the set sleeve A double mechanical seal cartridge having a seal and a second mechanical seal mounted thereon is provided between the back wall and the partition wall and the rotating shaft.
[0021]
According to the sixth invention , the first mechanical seal and the second mechanical seal are unitized as a double mechanical seal cartridge, and positioning when mounting the double mechanical seal is to fix the outer peripheral side of the cartridge to the partition wall. Made in Then, a sufficient amount of lubricating oil is directly supplied to the sliding contact portions of the first mechanical seal and the second mechanical seal via the lubricating oil supply port having a large opening.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to the drawings.
First, the configuration of the present embodiment will be described with reference to FIG.
The pump 10 which is a spiral pump is comprised by the impeller 12, the rotating shaft 14, the casing 16, and the bearing box 32 like the conventional one. A lubricating oil chamber 22 and a sealed space 26 are provided around the rotary shaft 14 between the casing 16 and the bearing box 32. The lubricating oil chamber 22 and the sealed space 26 are separated from each other by a partition wall 24, and the partition wall 24 has a rotation shaft hole 20M through which the rotation shaft 14 passes.
[0023]
The rear wall 18 of the casing 16 has a rotation shaft hole 20C through which the rotation shaft 14 passes. The rotary shaft hole 20 </ b> C and the rotary shaft 14 are sealed with a first mechanical seal 40 that constitutes a part of the double mechanical seal 38.
The first mechanical seal 40 includes a first fixed ring 42 attached to the inner peripheral surface of the rotary shaft hole 20C and a first rotary ring 44 attached to the outer peripheral surface of the rotary shaft 14. The stationary ring 42 is pressed and urged by a spring and is in sliding contact with the first rotating ring 44.
[0024]
The rotation shaft hole 20M and the rotation shaft 14 are sealed by a second mechanical seal 46 that constitutes a part of the double mechanical seal 38. The second mechanical seal 46 includes a second fixed ring 48 attached to the inner peripheral surface of the rotary shaft hole 20M and a second rotary ring 50 attached to the outer peripheral surface of the rotary shaft 14. The second stationary ring 48 is pressed and urged by a spring and is in sliding contact with the second rotating ring 50.
[0025]
The end face 34 of the bearing box 32 has a rotary shaft hole 20B through which the rotary shaft 14 passes, and the rotary shaft hole 20B and the rotary shaft 14 are sealed by an oil seal 52 similar to the conventional one.
Lubricating oil is sealed in the lubricating oil chamber 22.
The sealed space 26 includes a lubricating oil drain 54 and a liquid leakage sensor 56. The lubricating oil drain 54 has a configuration capable of discharging the lubricating oil accumulated in the sealed space 26 to the outside of the sealed space 26. The liquid leakage sensor 56 is similar to a conventional sensor capable of detecting the presence of liquid and has a configuration capable of detecting the lubricating oil accumulated in the sealed space 26.
[0026]
This embodiment is configured as described above, and the operation thereof will be described next.
During operation of the pump 10, the fluid to be fed also flows behind the impeller 12, and the rotary shaft hole 20C in the casing 16 is filled with the fluid to be fed. The rotation shaft hole 20 </ b> C and the rotation shaft 14 are sealed by a first mechanical seal 40, so that the fluid to be fed is prevented from leaking from the casing 16 into the lubricating oil chamber 22.
[0027]
In the first mechanical seal 40, the lubricating oil flows from the lubricating oil chamber 22 into the sliding contact portion between the first fixed ring 42 and the first rotating ring 44, and the sliding contact portion is lubricated by the lubricating oil. Thus, dry sliding is prevented.
The rotation shaft hole 20M and the rotation shaft 14 are sealed with a second mechanical seal 46, and the lubricating oil in the lubricating oil chamber 22 is prevented from leaking into the sealed space 26. Also in the second mechanical seal 46, the lubricating oil flows from the lubricating oil chamber 22 into the sliding contact portion between the second stationary ring 48 and the second rotating ring 50, and this sliding contact portion is always lubricated by the lubricating oil. The state is maintained and dry sliding is prevented.
[0028]
The lubricating oil chamber 22 has a large capacity, and since the retained lubricating oil is sufficient to always lubricate the first mechanical seal 40 and the second mechanical seal 46, the lubricating oil is continuously supplied. There is no need, and there is no need to install a lubricant tank or an attached installation.
The rotation shaft hole 20B and the rotation shaft 14 are sealed with an oil seal 52, and even if the lubricating oil leaks and accumulates in the sealed space 26, the lubricating oil cannot immediately enter the bearing box 32. Absent. When the lubricating oil accumulates in the sealed space 26, the leak sensor 56 detects this lubricating oil, and according to this detection signal, the lubricating oil in the sealed space 26 can be discharged through the lubricating oil drain 54, and the lubricating oil leaks from the oil seal 52. Intrusion into the bearing box 32 is prevented beforehand.
[0029]
Therefore, even if the lubricating oil in the lubricating oil chamber 22 is contaminated by the delivered fluid that has leaked through the first mechanical seal 40, the contaminated lubricating oil leaks from the lubricating oil chamber 22 into the sealed space 26. This is prevented by the second mechanical seal 46, and even if the lubricating oil contaminated from the second mechanical seal 46 leaks into the sealed space 26, the contaminated lubrication is caused from the sealed space 26. By properly discharging the oil, the contaminated lubricating oil is prevented from entering the bearing box 32, and the bearing 36 is also prevented from being damaged by the contaminated lubricating oil.
[0030]
In the present embodiment, the lubricating oil drain 54 and the liquid leakage sensor 56 are provided in the sealed space 26. However, a configuration as shown in FIG. 2 is also possible. That is, an auxiliary sealed space 28 connected to the lower portion of the bearing box 32 via the communication path 30 is formed, and instead of providing the lubricating oil drain 54 and the leak sensor 56 in the sealed space 26, the auxiliary sealed space 26 is provided. 28 is provided with a lubricating oil drain 54b and a leak sensor 56b.
[0031]
When the auxiliary sealed space 28 is provided, the capacity for storing the lubricating oil leaked from the lubricating oil chamber 22 is further increased, and the frequency and labor of discharging the leaked lubricating oil can be reduced.
Next, a second embodiment of the present invention will be described with reference to the drawings.
First, the configuration of the present embodiment will be described with reference to FIGS. 3 and 4. In addition, the same code | symbol is attached | subjected about the structure similar to the structure in 1st Embodiment, and the overlapping description is abbreviate | omitted.
[0032]
The pump 10 shown in FIG. 3 includes an impeller 12, a rotating shaft 14, a casing 16, and a bearing box 32. The pump 10 includes a lubricating oil chamber 22, a partition wall 24, and a sealed space 26. And a liquid leakage sensor 56.
As shown in FIG. 4, the first mechanical seal 41, the second mechanical seal 47, and the set sleeve 64 are provided between the rotary shaft hole 20 </ b> C of the back wall 18 of the casing 16 and the rotary shaft hole 20 </ b> M of the partition wall 24. A cartridge of the double mechanical seal 39 configured is provided. The first mechanical seal 41 has a first fixed ring 42 and a first rotating ring 44 that are in sliding contact with each other, and the second mechanical seal 47 is a second fixed ring 48 and a second rotating ring that are in sliding contact with each other. 50.
[0033]
In this cartridge, the first fixed ring 42 is mounted on the inner peripheral surface of the set sleeve 64 on the rotary shaft hole 20C side, and the second fixed ring 48 is mounted on the inner peripheral surface of the rotary shaft hole 20M side. A first rotating ring 44 and a second rotating ring 50 are mounted side by side between the fixed ring 42 and the second fixed ring 48, and the first fixed ring 42 is provided by a spring 66 included in the set sleeve 64. Is pressed and urged toward the first rotating ring 44, and the second fixed ring 48 is pressed and urged toward the second rotating ring 50 to constitute an integrated unit.
[0034]
The set sleeve 64 has a lubricating oil supply port 68 having a large opening area penetrating from the outer peripheral surface to the inner peripheral surface in the central portion in the axial direction, and the first fixed ring 42 and the first rotation through the lubricating oil supply port 68. The sliding contact portion of the ring 44 and the sliding contact portion of the second fixed ring 48 and the second rotating ring 50 communicate with the lubricating oil chamber 22.
This embodiment is configured as described above, and the operation thereof will be described next.
[0035]
During operation of the pump 10, the rotary shaft hole 20C is filled with the fluid to be delivered. The rotation shaft hole 20 </ b> C and the rotation shaft 14 are sealed by a first mechanical seal 41, so that the fluid to be fed is prevented from leaking into the lubricating oil chamber 22.
In the first mechanical seal 41, the lubricating oil in the lubricating oil chamber 22 is not obstructed by the set sleeve 64 from the lubricating oil supply port 68 at the sliding contact portion between the first fixed ring 42 and the first rotating ring 44. The sliding contact portion is always lubricated by lubricating oil, and dry sliding is prevented.
[0036]
The rotation shaft hole 20M and the rotation shaft 14 are sealed by a second mechanical seal 47, so that the lubricating oil is prevented from leaking from the lubricating oil chamber 22 into the sealed space 26. Also in the second mechanical seal 47, the lubricating oil flows into the sliding contact portion between the second fixed ring 48 and the second rotating ring 50 from the lubricating oil supply port 68 without being obstructed by the set sleeve 64. The part is always lubricated with lubricating oil to prevent dry sliding.
[0037]
The lubricating oil chamber 22 holds an amount of lubricating oil sufficient to always lubricate the first mechanical seal 41 and the second mechanical seal 47, and it is also necessary to provide a lubricating oil tank and attached piping. Absent.
A typical double mechanical seal cartridge has a set sleeve on the inner peripheral side and a first mechanical seal and a second mechanical seal on the outer peripheral side. The first fixed ring, the first rotating ring, The lubricating oil is supplied to the sliding contact portion between the mechanical seal and the set sleeve through a narrow gap formed between the mechanical seal and the set sleeve. The amount of lubricating oil flowing through this gap is small, and it was difficult to supply a sufficient amount of lubricating oil. However, this cartridge can be directly supplied from the lubricating oil supply port 68 having a large opening area, and good lubrication is performed. Is called.
[0038]
The rotation shaft hole 20B and the rotation shaft 14 are sealed by an oil seal 52. Even if the lubricating oil leaks and accumulates in the sealed space 26, the lubricating oil immediately enters the bearing box 32. There is nothing. When the lubricating oil accumulates in the sealed space 26, the liquid leakage sensor 56 detects the lubricating oil, and the lubricating oil can be discharged from the lubricating oil drain 54 in accordance with this detection signal.
[0039]
Therefore, even if the lubricating oil in the lubricating oil chamber 22 is contaminated by the delivered fluid that has leaked through the first mechanical seal 41, the contaminated lubricating oil leaks into the sealed space 26 second. Even if the lubricating oil contaminated from the second mechanical seal 47 is leaked into the sealed space 26, the contaminated lubricating oil is appropriately discharged from the sealed space 26, Contaminated lubricating oil is prevented from entering the bearing box 32.
[0040]
The cartridge of the double mechanical seal 39 is mounted from the impeller 12 side, and positioning is performed by fixing the outer peripheral surface to a predetermined position of the partition wall 24. Therefore, the mounting is simplified, and assembly, disassembly, maintenance, etc. of the pump 10 are performed. Work is done efficiently.
In the present embodiment, the lubricating oil drain 54 and the liquid leakage sensor 56 are provided in the sealed space 26. However, an auxiliary sealed space connected to the sealed space 26 via the communication path is formed below the bearing box 32. Instead of providing the lubricating oil drain 54 and the liquid leakage sensor 56 in the sealed space 26, it is possible to provide a lubricating oil drain and a liquid leakage sensor in the auxiliary sealed space.
[0041]
【The invention's effect】
Since the present invention has the shaft seal structure of the pump as described above, in the pump having the shaft seal structure of the double mechanical seal, the capacity of the lubricating oil chamber is increased and a sufficient amount of the sliding contact portion of the double mechanical seal is provided. Lubricating oil can be supplied, and the lubricating oil contaminated with the delivered fluid can be prevented from leaking into the bearing box.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pump provided with a shaft seal structure according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a pump having a shaft seal structure according to a modification of the first embodiment.
FIG. 3 is a sectional view of a pump provided with a shaft seal structure according to a second embodiment of the present invention.
4 is an enlarged view of the double mechanical seal of FIG. 3. FIG.
5 is a cross-sectional view of a pump including a shaft seal structure according to Conventional Example 1. FIG.
6 is a cross-sectional view of a pump including a shaft seal structure according to Conventional Example 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pump 12 Impeller 14 Rotating shaft 16 Casing 18 Casing back wall 20C, 20M, 20B Rotating shaft hole 22 Lubricating oil chamber 24 Partition 26 Sealed space 28 Auxiliary sealed space 30 Communication path 32 Bearing box 34 Bearing box end surface 36 Bearing 38, 39 Double Mechanical seal 40 First mechanical seal 42 First fixed ring 44 First rotary ring 46 Second mechanical seal 48 Second fixed ring 50 Second rotary ring 52 Oil seal 54 Lubricating oil drain 56 Leak sensor 64 Set sleeve 66 Spring 68 Lubricating oil supply port

Claims (5)

In a pump comprising a casing, an impeller, a rotation shaft of the impeller, and a bearing box that supports the rotation shaft,
Around the rotating shaft between the back wall of the casing and the bearing box, a lubricating oil chamber and a sealed space separated by a partition wall are provided,
A first mechanical seal is provided between the back wall and a rotary shaft penetrating the back wall; a second mechanical seal is provided between the partition wall and the rotary shaft penetrating the partition wall;
A shaft seal structure for a pump, wherein a lubricating oil is sealed in a lubricating oil chamber, and an auxiliary sealed space communicating with the sealed space is provided in at least one of a casing and a bearing box . 2. The shaft seal structure for a pump according to claim 1, wherein an auxiliary sealed space is provided in a lower portion of the bearing box . In a pump comprising a casing, an impeller, a rotation shaft of the impeller, and a bearing box that supports the rotation shaft,
Around the rotating shaft between the back wall of the casing and the bearing box, a lubricating oil chamber and a sealed space separated by a partition wall are provided,
A first mechanical seal is provided between the back wall and a rotary shaft penetrating the back wall; a second mechanical seal is provided between the partition wall and the rotary shaft penetrating the partition wall;
The lubricating oil is sealed in the lubricating oil chamber, the shaft seal structure of the pump characterized in that a leakage sensor in a closed space. 3. The pump shaft sealing structure according to claim 1 , wherein a leakage sensor is provided in the auxiliary sealed space . The double mechanical seal cartridge in which the first mechanical seal and the second mechanical seal are mounted on the inner peripheral side of the set sleeve is provided between the back wall and the partition wall and the rotating shaft. The shaft seal structure of the pump according to any one of 1 to 4 .

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