JPS6354157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft sealing device that protects the shaft sealing portion of a pump by forming an air layer between the shaft sealing portion and the pump internal liquid.

Today, shaft sealing devices for pumps are highly developed, and there are gland packing systems, oil seals, mechanical seals, etc., but in sand pumps and slurry pumps that handle liquids containing solids, these shaft seals are damaged due to solids in the liquid. At present, it is difficult to avoid damage to the equipment.

The present invention aims to provide a device that solves the above-mentioned drawbacks by forcibly interposing an air layer between the shaft seal and the liquid. In a pump having an inverted impeller behind a partition wall, the tip of a ventilation pipe that passes through the seal cover and leads to the outside is opened in the shaft seal between the inverted impeller and the shaft sealing device, and the same This is a shaft sealing device for a pump characterized in that a check valve is provided at a required position of a ventilation pipe. In addition, in the case of vertical shaft type submerged pumps, the bearings are damaged due to dew droplets and intruding water generated inside the outer cylinder, so in order to eliminate this drawback, a partition wall is installed behind the main impeller with a back blade. In a vertical shaft type submerged pump having a reverse impeller, an air intake hole is provided at the upper end of the outer cylinder that protects the drive shaft, and small holes are formed vertically through each bearing in the outer cylinder, The other end of the communication pipe, one end of which communicates with the small hole at the bottom, passes through the seal cover and opens at the shaft periphery between the reverse impeller and the shaft sealing device, and a non-return check is provided at a required position of the communication pipe. A pump shaft sealing device characterized by being provided with a valve is effective.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing an embodiment in which the present invention is applied to a tank external type vertical shaft slurry pump integrated with a motor. A shaft sealing device 5 is attached above the reverse impeller 2, and a bearing 6 is disposed further above the shaft sealing device 5. In the figure, 7 is a seal cover, 8 is a casing, 9 is a suction port, 10 is a discharge port, and 11 is a bed.

In the pump shown in FIG. 1, a vent pipe 13 is opened in the space 12 between the inverted impeller 2 and the shaft sealing device 5, passing through the seal cover 7 and leading to the outside. A check valve 14 as shown in an enlarged view in FIG. 2 is provided at the outer end so that air can only enter the inside.

If this pump device with the above configuration is installed outside the tank at the same position as the bottom of the tank, and the pump suction port 9 is connected to the piping near the bottom of the tank, the water in the tank will flow inside the pump. into the pump outlet 1
The discharge pipe connected to the water tank will be raised to the same height as the tank water level.

In the pump, the air also flows into the reverse impeller 2, and the air inside is pushed upward and remains in the lower space 12 of the shaft sealing device 5 and above the reverse impeller 2, and the water level of the water tank is The pressure becomes equal to the pressure and it comes to rest.

In this case, the check valve 14 is closed because the pressure in the space 12 becomes higher than the outside atmospheric pressure.

If you start the pump in this condition, impeller 1
The main blade starts pumping water from the aquarium. At the initial stage of startup, the pressure inside the pump casing 8 has not risen sufficiently, so the back blade provided on the main impeller 1 also performs a pumping action, pumping up the water around the reverse impeller 2, which causes the space to rise. When the pressure in the section 12 becomes lower than the atmospheric pressure, air is taken in through the check valve 14, but when the pressure inside the pump casing increases and becomes normal pressure, the impeller 1 becomes the same as when the outer diameter of the main blade and the outer diameter of the back blade are the same. The water pumping action is approximately equal to the pressure, and the water tank water level pressure is applied to the suction end of the main impeller, and the pressure inside the pump casing is the sum of the water tank water level pressure and the pressure generated by the main impeller. The water inside the casing becomes larger than the pressure generated by the blade, and the water inside the casing flows back inside the back blade, but when it reaches the inside of the reverse impeller 2, the pumping action of the reverse impeller 2 works, and the water becomes balanced, and the reverse flow is caused by the reverse impeller 2.
It stops at a radial position midway inside, and air remains on the inner circumferential side, which prevents the pumped liquid from coming into direct contact with the shaft sealing device 5.

However, as is known, it is not possible to achieve a complete shaft seal no matter what kind of shaft sealing device is used, and sealing a gaseous shaft is much more difficult than sealing a liquid shaft. The remaining air is also dissipated and reduced due to leakage from the shaft sealing device 5, the check valve 14, or the action of air mixture within the reverse impeller 2.

However, even in such a case, in the case of the device of the present invention, by setting the generated pressure of the reverse impeller 2 to an outer diameter of the reverse impeller 2 whose capacity is greater than the pressure equivalent to the water tank water level, it is possible to ensure against reverse flow. However, when the pressure in the space 12 becomes lower than atmospheric pressure, external air is sucked in through the check valve 14 to ensure the amount of air and prevent a large negative pressure.

Therefore, unlike the conventional method of providing an air layer below this type of shaft sealing device, the pump characteristic curve is a stable curve, the water depth is shallow, and the pump head is sufficiently high (30M or more). There is no need to set any restrictive conditions, and the pump can be made highly reliable.

Generally, a foot valve is not used in the suction piping of sand pumps and slurry pumps, and a check valve is provided in the discharge piping, but in the case of low-lift pumps, the check valve in the discharge piping is often omitted. Therefore, when the pump is stopped, a backflow of pumped water occurs.

In this case, a pressure lower than the actual head is temporarily applied inside the pump casing, so the reverse impeller 2 and the space 12 are also raised to the same pressure, but the pump casing 8
is open to the water tank via the suction pipe, and most of the pressure applied is due to flow velocity and pipe resistance, so the pressure does not become large.

Next, FIG. 3 shows an embodiment of a horizontal shaft type slurry pump, and the structure and function of the shaft water sealing section are the same as those in FIG. 1.

As described above, according to the invention recited in claim 1 of the present patent application shown in FIGS. By providing the wheel 2 and configuring it so that outside air can be introduced into the space 12 in front of the inlet of the reverse impeller 2 and below the shaft sealing device 5 with a check valve 14 interposed, Although the pressure applied to the sealing device 5 is applied depending on the water level of the water tank when the pump is stopped, it is kept almost equal to atmospheric pressure when the pump is in operation, and moreover, at the time of startup and during operation, the pressure is applied to the space 12 while drawing in insufficient air. By ensuring air is interposed, it is possible to prevent the pumped liquid from directly contacting the shaft sealing device 5, and there is an effect that the shaft sealing device 5 is not damaged by solids contained in the pumped liquid.

Next, the invention recited in claim 2 of the present application will be described in detail with reference to FIG. This invention also has the same concept of isolating the shaft sealing device from the liquid with an air layer, but it also has the same concept as the above-mentioned invention. This device is designed to eliminate damage to the bearing 6' at the same time. In other words, in a vertical shaft type submerged pump, the drive shaft 4, which is longer than the motor 3, is extended downward, the main impeller 1 with back blades, the reverse impeller 2, etc. are installed at the bottom, and an outer cylinder for protecting the drive shaft 4 is installed. Bearings 6', 6', . . . are arranged within the bearing 15 at required intervals. In this device, an air intake hole 16 is provided through the upper end of the outer cylinder 15 in a portion exposed to the air.
A small hole 17 is provided through each bearing 6' in the bearing. Also, a communication pipe 13' whose one end is connected to the small hole 17 at the lowest stage is passed through the seal cover 7, and the other end is connected to the reverse impeller 2.
This structure opens to a space 12 between the shaft sealing device 5 and the shaft sealing device 5. In this illustrated example, the check valve 14 is provided at a lower portion of the communication pipe 13'.

In the device configured as shown in FIG. 4, water droplets generated in the outer cylinder 15 or infiltrated water that enters by some means sequentially flow downward through the small holes 17 penetrated through each bearing 6' and finally reach the communication pipe 13'. It flows inside and accumulates there.

When the pump is driven, the space 12 between the inverted impeller 2 and the shaft sealing device 5 becomes negative pressure, so that the communication pipe 1
The water accumulated in 3' is taken into the pump inner space 12 through the check valve 14 along with the air, and is discharged as pumped water from the discharge port 10 by the pumping action of the back blades of the reverse impeller 2 and the main impeller 1. After the water in the outer cylinder 15 is removed, air is taken in, and the pressure in the space 12 is maintained at approximately the same pressure as the atmosphere. Next, when the pump is stopped, due to the action of the check valve 14, the air in the space 12 and the air on the inner circumferential side of the reverse impeller 2 have no escape route, so the water tank level pressure is raised above the liquid level in the pump. This air layer prevents the liquid from coming into direct contact with the shaft sealing device.

As described above, the invention described in claim 2 of the present invention, in addition to the effect of the invention described in claim 1, eliminates dew droplets and intrusion water that occur inside the outer cylinder due to temperature changes and other factors, and This has the effect of reducing and preventing problems caused by rusting of bearings, etc.

[Brief explanation of the drawing]

Fig. 1 is an explanatory cross-sectional view of an embodiment in which the invention recited in claim 1 of the present application is applied to a tank external vertical shaft slurry pump, Fig. 2 is an enlarged sectional view of the same check valve portion, and Fig. 3 is an explanatory cross-sectional view of an embodiment in which the invention described in claim 1 of the present patent application is applied to a tank external vertical shaft slurry pump. FIG. 4 is a cross-sectional explanatory diagram of an embodiment in which the invention as claimed in claim 1 is applied to a horizontal shaft type slurry pump. Figure 5 is a cross-sectional explanatory diagram of the main part. In the figure, 1: Main impeller with back blade, 4: Drive shaft,
5: Shaft sealing device, 12: Space, 13: Ventilation pipe, 1
4: Check valve.

Claims (1)

[Scope of Claims] 1. In a pump having an inverted impeller with a partition wall behind the main impeller with a back impeller, a seal cover may be penetrated around the shaft between the inverted impeller and the shaft sealing device. A shaft sealing device for a pump, characterized in that the tip of a vent pipe leading to the outside is opened, and check valves are provided at required positions on the vent pipe. 2. In a vertical shaft type submerged pump having a reverse impeller with a partition wall behind the main impeller with a rear blade, an air intake hole is provided at the upper end of the outer cylinder that protects the drive shaft, and an air intake hole is provided in the upper end of the outer cylinder that protects the drive shaft. A small hole is formed vertically through each of the bearings, and the other end of the communication tube, one end of which is communicated with the bottom small hole, is passed through the seal cover and connected to the shaft periphery between the reverse impeller and the shaft sealing device. A shaft sealing device for a pump, characterized in that it is opened and furthermore, a check valve is provided at a required position of the communicating pipe.