JPS6020596B2 - Submersible pump shaft sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft sealing device for a rotating shaft of a submersible suction pump as a mud lifting device in a muddy water construction method.

BACKGROUND ART In muddy water construction methods such as reverse circulation drills, a suction pump submerged in water for discharging excavated sand along with water to the ground has been put into practical use.
It is mounted directly above the drilling bit and advances deeper underground with the drilling bit as the drilling progresses. The problem here is that as the depth increases, the water pressure inside the borehole increases, and the pressure difference between the external pressure and the internal pressure of the submersible pump increases, requiring improved performance of the submersible pump's rotating shaft seal. be. Normally, suction pumps are installed on land, but the purpose of submerging them in water is to take advantage of the fact that the pump's performance is not limited to the suction head and can replace the entire head with the discharge head. The aim is to increase the mud ratio and to make it possible to pump water when the excavation depth becomes deeper. Therefore, a rotary shaft seal with very high performance is required for a submersible pump type shaft excavator. Therefore, as a method that can be used without increasing the rotary shaft sealing performance, a method has been devised in which a pressure medium is fed into the housing from the ground and circulated, so that the working pressure is higher than the external pressure.

Similar examples are disclosed in Japanese Utility Model Publication No. 48-21521, Japanese Unexamined Utility Model Publication No. 155005-1980, Japanese Unexamined Utility Model Publication No. 7644-1988, Japanese Utility Model Application Publication No. 49-9003, and Japanese Utility Model Application No. 49-10307. However, these proposals have the disadvantage that means for feeding the pressure medium must be prepared separately. By using a hydraulic motor as the recirculating drive source without separately feeding this pressure medium, the drain oil of the hydraulic motor is branched from the middle and guided to the rotating shaft sealed chamber, reducing the head pressure up to the oil tank on the ground. Tokuko Sho was developed as a system that acts on the koji sealing chamber, limits the internal and external pressure chambers to the difference in specific gravity of the external muddy water, eliminates special pressure loading means, and simplifies the internal and external pressure adjustment mechanism. No. 52-9921 is disclosed.

This device utilizes the pressure of drain oil from a hydraulic motor that rotates a cutter in an excavator.

Since the rotation speed of the cutter varies depending on the soil quality, the amount of drain oil in the hydraulic motor also changes. For this reason, some measures have been taken to ensure that only the head pressure is always applied so that the pressure remains constant even if the oil amount changes. Therefore, there is always a pressure difference due to the difference in specific gravity between hydraulic oil and mud water, and this pressure difference increases as the depth increases, and in the case of submersible pumps, the discharge head pressure is further applied to the shaft seal. Therefore, the internal pressure is always lower than the external pressure. For this reason, if a mechanical seal is used where a small amount of leakage is unavoidable, or if the seal is damaged due to its lifespan during use, leakage will always occur from the high pressure side to the low pressure side, so muddy water etc. will leak from the outside. There is a concern that this may cause problems with bearings, hydraulic motors, and even hydraulic equipment on the ground. The present invention relates to an improvement of the above-mentioned Japanese Patent Publication No. 52-9921, and reduces the pressure of the discharge head of a submersible pump that is applied to the shaft sealing part, thereby reducing the sealing pressure of the sealing part in contact with external liquid. In addition, by utilizing the pressure caused by the pipe resistance generated when the drain oil of the hydraulic motor is guided to the oil tank, the internal pressure is always maintained even when the excavation depth increases while the Fuji seal part is rotating. so that it is higher than the external pressure,
It is an object of the present invention to provide a highly reliable shaft sealing device for a submersible pump that prevents leakage from the shaft sealing portion to the outside but the opposite.

In order to achieve this object, the present invention arranges the shaft seals of a submersible pump driven by a hydraulic motor in two stages, upper and lower, and provides a back blade on the inflator of the submersible pump, and also provides the shaft seals of a submersible pump driven by a hydraulic motor. A labyrinth seal is formed integrally with the invera, and the housing is provided with a through hole through which a part of the liquid pumped by the submersible pump is guided to the lower seal through the labyrinth seal and then released to the outside, and the upper and lower seals are connected to the upper and lower seals. A space chamber filled with a liquid such as hydraulic oil is formed in between, and a pressure equalizer is installed to constantly balance the internal pressure and external pressure in the space chamber. The structure is configured such that the drain oil of the motor is inflowed and filled, and the drain oil is returned to the oil tank via the drain piping and a pipe resistance adding means provided in the middle of the drain piping, and the shafted seal is prevented when the hydraulic motor is driven. It is characterized in that the internal pressure of the internal space is made higher than the external pressure by the pipe resistance means.

Hereinafter, one embodiment of the present invention will be explained according to FIGS. 1 to 3.
This will be explained more specifically.

FIG. 1 is an overall side view showing a state in which a pit excavator according to the present invention is in the middle of excavating a pit. Reference numeral 1 denotes a base installed on the ground, and a rotary table 2, which is an excavation torque supply device, is fixed on the base.

A Kelly bar 3 is inserted into the center of the rotary table 2 and engaged in a shape that allows it to receive excavation torque as the rotary table 2 rotates. It is configured to drive a drill pipe 4, a cross-over sub 5, a stabilizer 6, a submersible pump unit 7 with a stabilizer, and a bit 8, which are sequentially connected to the lower end of the Kelly bar 3. A swivel joint 9 is connected to the upper part of the Kelly bar 3, and a hydraulic rotary joint 10 is connected to the upper part of the swivel joint 9, so that pressure oil supplied through a hydraulic hose from a hydraulic motor unit 11 installed on the ground is connected to the submersible pump. It is designed to lead to unit 7. In addition, a suspension 9a is attached to the swivel joint 9,
A drill string from a swivel joint 9 to a bit 8 is suspended by a crane 12. Further, a suction port is provided at the center of the lower end of the bit 8, and the excavated earth and sand is sucked up together with water by the drive of the submersible pump unit 7, and passes through the inner cylinder of each drill string.
Delivery hose 1 attached to swivel joint 9
3 to the settling tank 14. Then, the supernatant liquid is sucked up by a submersible pump 15 installed in the settling tank 14 and returned to the borehole. By repeating this process, a pit is excavated. Next, the drive system of the submersible pump unit 7 will be explained using FIG.

The oil tank 16 of the hydraulic pump unit 11 installed on the ground is divided into two tanks.
Hydraulic oil is sucked up from a through the filter 7 by a hydraulic pump 19 driven by an electric motor 18. Then, by operating the control valve 20 from the illustrated neutral state to the "hydraulic motor forward rotation" side, the hydraulic fluid is introduced into the piping that rotates the hydraulic motor 21 in the forward direction, and then the hydraulic fluid is introduced into the rotary joint 10 shown in FIG. From the fixed boat,
It flows through the internal pipe to the rotating side internal pipe located in the center, and is guided to the Kerry bar 3 through the internal pipe of the swivel joint 9. Here, even if the drill string rotates, the rotary joint 10 is provided with a rotation stopper OA on the fixed side so that the hydraulic hose extending from the hydraulic pump unit 11 to the rotary joint does not rotate. Then, the hydraulic oil that has done work in the hydraulic motor 21 goes through the external piping of the drill pipe 4, cross-over sub 5, and stabilizer 6, and is guided from the Kelly bar 3 to the hydraulic motor 21 of the submersible pump unit 7. Follow the path and return to the second oil tank 16b.And,
The oil passes through the filter 29 and flows into the first oil tank 16a again. In the middle of this return piping, there is a line filter 2 equipped with a clogging detector and a bypass circuit in case of clogging.
2. It is equipped with an oil cooler 23 that operates only when the oil temperature is high. The hydraulic pump 19 is equipped with an electric regulator 24 to change the discharge amount. Further, the pressure setting of the discharge amount is performed by the relief valve 25. Drain oil from the hydraulic motor 21 passes through a drain pipe 26, passes through a line filter 27 with a clogging detector and a bypass circuit in case of clogging, and a sequence valve 28, and flows into the third oil tank 16c.
The hydraulic oil overflowing from the third oil tank 16c flows into the first oil tank 16a. The second barrel oil tank 16b is the third barrel oil tank 16c, and each of the first barrel oil tanks 16
The reason why the manner of inflow into a is different is due to the difference in the amount of inflow of each hydraulic fluid. That is, the drain oil amount to the third oil tank 16c is 2 to 5% of the discharge amount of the hydraulic pump 19, while the return oil amount to the third oil tank 16b is 2% to 5% of the discharge amount of the hydraulic pump 19. 19 is very large, approximately 95 to 98% of the discharge amount, so if muddy water or the like is mixed in the oil, there is a risk that it will flow into the first oil tank 16a without settling in the oil tank 16b. This is due to consideration of this point. Capacitance-type muddy water mixing detectors 30 and 31 attached to the oil tanks 16b and 16c, respectively, detect the capacitance of the hydraulic oil and the capacitance when muddy water gets mixed into the tank. Detecting the change, hydraulic pump 1
This is to stop the drive of 9. Similarly, if the line filters 22, 27 become clogged, it is detected electrically and an alarm is sounded. This is because the borehole is filled with muddy water, so if the piping inside the borehole or the shaft sealing device of the submersible pump is severely damaged and muddy water gets mixed in, the problem can be caught quickly and it can lead to serious problems. This allows countermeasures to be taken in advance. Furthermore, each drill pipe is provided with external piping as described above, and when the drill pipes are connected, these external pipings are connected to each other by self-sealing joints 32 and 33.

Note that when the control valve 20 is operated from the neutral state to "hydraulic motor reverse rotation", the piping exiting the control valve 20 of the hydraulic pump unit 11 is
The ``forward'' and ``return'' directions are reversed in the case of forward rotation.

Further, 34 indicates a bell gauge, and 35 indicates a mud water mixing monitoring window. Next, based on FIG. 2, the submersible pump unit 7
The configuration will be specifically explained. The submersible pump unit 7 is
It is installed directly above the bit 8, and the pump suction and discharge port diameters are the same so that excavated earth and sand will not clog the pump.

The pump is a centrifugal pump, and the invera 3 inside the casing 36
7 is driven by a hydraulic motor 21 via a shaft 38. The shaft 38 is connected to the shaft of the hydraulic motor 21 by a chain coupling 39. and,
The shaft 38 has a bearing 41 attached to the housing 40' and a bearing 4 attached to the housing 42.
3 is supported. A case 44 is interposed between the hydraulic motor 21 and the housing 40, which are connected to each other by bolts while being sealed by O-rings 45 and 46, respectively. The case 44 is provided with lids 47 on the left and right sides for attaching the chain coupling 39.
It is attached with bolts through an O-ring. Since the shaft of the hydraulic motor 21 is not provided with a seal, drain oil flows into the case 44. A plurality of through holes 49 are bored in the upper part of the housing 40 so that the drain oil filled in the case 44 and the vertical seal space C in the housing 40 can easily circulate. There is. An outlet (not shown) for draining oil is provided at the bottom of the housing 40.
The housing 40 and the housing 42 are connected by bolts with a ring 50 in between. An air vent hole 51 is bored in the upper part of the space A formed in the housing 42 and is closed by a plug 52 . An upper rotary shaft seal 55 and a lower rotary shaft seal 56 are installed spaced apart between the housing 42 and the sleeve 54 which rotates integrally with the shaft 38 by a key 53 at the lower part of the bearing 43. The space between the upper rotary shaft seal 55 and the lower rotary shaft seal 56 communicates with the space A of the housing 42 . A bellows type pressure equalizer 57 and a cover 58 are exposed and attached to the housing 42 . The inner diameter of the cover 58 is set to be approximately equal to the outer diameter of the pressure equalizer 57 when it is pressurized to its maximum, with a slight gap. Therefore, when expanding and contracting the pressure equalizer,
Since the inner folded portion of the cover 58 has a guiding shape, it can be attached laterally. Further, the bellows of the pressure equalizer 57 is not spiral-shaped but is formed by an assembly of rings, and a discharge port 5 is provided on the bottom surface of the cover 58.
A plurality of holes 8a are bored. For this reason, it is difficult for mud to adhere to the bellows, and it can be easily discharged, resulting in a thick structure that does not interfere with expansion and contraction of the bellows. This is because the expansion and contraction of the hydraulic fluid filled in the space A of the housing 42 due to heat and the balance between the internal pressure and the external pressure of the space A are necessary to ensure smooth expansion and contraction. Also,
The length of the cover 58 is set to have a margin for the amount of expansion and contraction of the bellows. A discharge port is provided at the bottom of the space A of the housing 42 and is closed by a plug 59 . In addition, thin back blades 37a and 37b are attached to the inflator 37 in order to reduce the pressure on the back side thereof.

The invera 37 is inserted through a shaft 38 and a key 60 so as to rotate together, and the invera nut 61
It is prevented from falling out by. Further, a plate 62 is attached to the housing 42 connected to the casing 36, and the plate 62 and the inflator 37 form a labyrinth seal 62a. This can prevent large fluids from entering the space B formed between the boss portion of the inflator 37 and the housing 42. Moreover, the housing 42 is directed toward this space B.
A fixed blade 42a is provided at . This is installed with the aim of preventing wear around the space B caused by the earth and sand flowing in through the back blade 37a of the inflator 37 swirling in the space B. However, since it is also necessary to cool the lower rotary shaft seal 56, a through hole 63 leading to the outside is provided to guide the tin liquid from the back blade 37a. In other words, the total length of a submersible pump for construction is usually about 10 to 20 m, and the internal pressure of the casing 36 is always 1 to 2 k9 higher than the external pressure. It is. The present invention is constructed as described above, and the space A shown in FIG. When this occurs, the pumped liquid flows into space A. As a result, the pressure equalizer 57 gradually swells, and the shape of the bellows eventually collapses, causing the cover 5
It will stick perfectly to the inner wall of 8. However, if the upper rotating shaft seal 55 is not damaged, there is no risk of causing trouble to the rotating shaft sealing section. Since the pressure equalizer 57 is lifted to the ground level after one excavation hole has been dug, abnormalities can be detected by inspecting the pressure equalizer 57 at this time. Next, consider the seal pressure of the upper rotating shaft seal.
If we consider the head pressure of the hydraulic oil as disclosed in Japanese Patent Publication No. 52-9921, then the seal pressure can be considered as the ratio of the specific gravity of the muddy water, 1.1, to the specific gravity of the hydraulic oil, 0.85. Therefore, at a depth of 100 feet, it is 2.5k9/
Female seal pressure. However, since the aim of the present invention is to make the drain pressure of the hydraulic oil, that is, the pressure in the ceramic sealing space C higher than the pressure in the space A, it is necessary to If we consider the worst situation where water flows from B into space A, the drain pressure should be 2.8 to 3.8 k.
9/ It is better to raise it higher than the ground. As mentioned above, the drain oil returns to the 2-5% oil tank at the discharge port of the hydraulic pump. Therefore, in a submersible pump that rotates at a nearly constant rotation rate during work, the amount of drain oil is also almost constant, and the piping resistance can be easily determined from this, so if the piping size is selected arbitrarily, the drain pressure Since the drain pressure can also be determined, setting the drain pressure is easy. In addition, there is a method of providing an orifice such as a variable throttle in the circuit 26 (not shown), and as shown in FIG.
．． By setting 8k9/Chu, housing 40,
The working oil pressure in 42 can be 2.8 to 3.8 kg/. Of course, it goes without saying that this value is a value assuming the excavation depth and the capacity of the submersible pump. Another method is to take advantage of the fact that as the excavation depth increases, the drill pipes 4 must be added.
For this joint, a self-sealing joint 33 shown in FIG. 3 may be used.

In this way, the size of the self-sealing joint 33 is selected in consideration of pressure loss. In other words, as the excavation depth increases, the pressure difference due to the difference in specific gravity between oil and mud increases, so if this increase is compensated for by the pressure loss of the self-seal joint 33, the seal pressure can be kept almost constant even if the excavation depth changes. can be kept. Furthermore, if the desired pressure loss cannot be obtained due to a small amount of drain oil, the return piping from the hydraulic motor 21 may be branched in the middle to allow the required amount of oil to flow to the drain piping. As described above, from the drain outlet of the hydraulic motor 21 to the oil tank 16c
If pressure loading means such as an orifice such as a variable restrictor, a sequence valve 28, and a self-shield joint 33 that takes pressure loss into account are used at any point in the drain piping 26,
The pressure within the shaft-sealed space C can always be set higher than the external pressure. Furthermore, if the sealing performance of the lower rotary shaft seal 56 is also improved, it will be possible to reduce the occurrence of trouble in the upper rotary shaft seal 55, which will lead to an improvement in the sealing performance of the entire sealing section device.

That is, the space A has a pressure almost equal to the external pressure, partly because the bellows type lagoon pressure device 57 is provided.
However, as mentioned above, when the submersible pump is operating, the pressure in space B is higher than the external pressure by about 1 to 2 k9/swim, so the seal pressure applied to the lower rotary shaft seal 56 is 1 This means ~2 kg/ground. Therefore, if this pressure difference can be reduced by 4, the lower rotating shaft seal 5
The burden on the sealing performance of No. 6 will also be reduced.
In the present invention, by providing the back blades 37a and 37b on the invera 37 and forming a labyrinth seal 62a between the plate 62 and the invera 37, the pressure in the space B can be reduced to 0.75k9/mass when the submersible pump is operated. It can be seen that the degree of deterioration is reduced. Therefore, the pressure in space B is 0
．． The lower rotating shaft seal 5
It is possible to measure the improvement in the sealing performance of 6. These seal pressures were taken into consideration during rotation, but seals are usually more severe during rotation or sliding than when they are stationary, and even if they have a considerable seal pressure when stationary, they are The general concept is that when sliding, even a small amount of sealing pressure may not be maintained.

Therefore, the best effects can be obtained by applying the present invention to ball seals during rotation and sliding, which are particularly problematic. As described above, according to the shaft sealing device for a submersible pump of the present invention, the drain oil of the hydraulic motor is filled in the shaft sealing section, and the pressure there is greater than the external pressure via the shaft seal at the excavation depth. A pressure loading means is provided in the middle of the drain piping so that the pressure is always high, and the shaft seals are arranged in two stages, upper and lower, and a space chamber filled with a liquid such as hydraulic oil is formed between the upper and lower seals, We have installed a lagoon pressure device that balances the internal pressure and external pressure within the space chamber, so if a mechanical seal is used where a slight leak is unavoidable, or if the seal breaks due to its lifespan during use, a slight gap will be prevented. Even if the hydraulic oil filled in the sealed part leaks to the outside, muddy water will never enter the sealed part from the outside, so there will be no trouble with bearings, hydraulic motors, etc. can be completely avoided from occurring.

In addition, a hair vane is attached to the in-bella of the submersible pump, and a labyrinth seal integrated with the in-bella is formed in the passage leading to the lower rotary shaft seal, thereby reducing the sealing pressure. By providing this, the tin liquid of the submersible pump can circulate and cool the lower rotary shaft seal, reducing the load on the sealing function of the lower rotary shaft seal.As a result, the reliability of the entire scale sealing device is improved. This can lead to improvement. Further, even if a leak occurs in the 01'' ring or the like that is in direct contact with external pressure, it is possible to prevent immediate damage to the liquid chamber filled with the hydraulic drain in which the sealed body such as the bearing is located.

[Brief explanation of drawings]

FIG. 1 is an overall side view of a pit excavator which is an embodiment of the submersible pump sealing device of the present invention, FIG. 2 is an enlarged sectional view of the submersible pump unit shown in FIG. 1, and FIG. The figure is a hydraulic circuit diagram for explaining the drive of the submersible pump unit and the principle of the sealing device of the present invention. 7... Submersible pump unit, 8... Bit, 21. ．．・Hydraulic motor, 26...Drain piping, 28...Sequence valve, 33...Self-seal joint ~ 36...Casing, 37...Invera, 37a, 37b...Fall blades,
38...Shaft, 40, 42...Housing, 44...
Case, 49...Through hole, 53...Sleeve, 55...Upper rotating shaft seal, 56...Lower rotation seal, 57...
Bellows type pressure equalizer, 58...Cover, 62...Plate, 6
2a... Labyrinth seal "A... Space of housing 42, B... Space formed between invera 37 and housing 42, C... Labyrinth seal space. Fig. 1 Fig. 2 Fig. 3

Claims (1)

[Claims] 1. Shaft seals of a submersible pump driven by a hydraulic motor are arranged in two stages, upper and lower, a back blade is provided on the impeller of the submersible pump, and a labyrinth seal integrated with the impeller is provided in the flow path to the lower seal. The housing is provided with a through hole through which a part of the liquid pumped by the submersible pump is guided to the lower seal through the labyrinth seal and then released to the outside, and liquid such as hydraulic oil is formed between the upper and lower seals. A pressure equalizer is installed to constantly balance the internal pressure and external pressure in the space chamber, and the drain oil of the hydraulic motor is supplied to the shaft-sealed space provided above the upper seal. At the same time, the drain oil is returned to the oil tank through the drain piping and a pipe resistance adding means provided in the middle of the drain piping, and the internal pressure of the shaft-sealed space is reduced when the hydraulic motor is driven. A shaft sealing device for a submersible pump, characterized in that the pipe line resistance means allows the pressure to be higher than the external pressure.