JP2623675B2 - Vertical shaft non-self-priming centrifugal pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a discharge chamber formed in an upper portion of a casing, a discharge port is opened, and a shaft sealing device is provided at an upper end of the casing so as to be located in the discharge chamber. A motor shaft is passed through the shaft sealing device, an impeller is attached to a lower portion of the motor shaft extending below the discharge chamber, a suction port is opened at a lower portion of the casing, and liquid sucked from the suction port is provided. The present invention relates to a vertical non-self-priming centrifugal pump that is pressurized by an impeller and discharged from a discharge port of a discharge port.

[Conventional technology]

Vertical shaft centrifugal pumps are classified into a self-priming type and a non-self-priming type according to the presence or absence of a self-priming function. The former is further classified into those having a self-priming chamber on the discharge side and those having a self-priming chamber on the suction side. If the self-priming chamber has a self-priming chamber on the discharge side, the self-priming chamber has a water / water separation function, but if the self-priming chamber is quite large and a small pump, the overall size and weight tend to be large. . Those with a self-priming chamber on the suction side
As disclosed in -117298, the sliding surface of the shaft sealing device can be lubricated with the pump handling liquid because the shaft sealing device is located on the suction side of the pump and is under a pressure lower than the atmospheric pressure. It is difficult and the life of the shaft sealing device is likely to be short.

Therefore, conventionally, as shown in FIG. 3, a non-self-priming type in which a shaft sealing device is positioned on the discharge side of a pump is known as a non-self-priming type.
In FIG. 3, the discharge casing 1a and the suction casing 1b
A casing 1 is formed from the above. A motor 3 is mounted on a shaft sealing device 2 such as a mechanical seal provided at the upper end of the casing 1.
, And two impellers 5 are attached to the tip of the shaft 4. The impellers 5 are respectively housed in an inner casing 7 provided with guide vanes 6 to form a two-stage centrifugal pump, and mounted in the casing 1. A discharge chamber 8 is formed in the upper part of the casing 1 and a discharge port 9 is opened.
The lower portion forms a suction chamber 10, and the suction port 11 is opened.
The liquid sucked in from the pipe 11a is pressurized by the pump and discharged from the pipe 9a of the discharge port 9.

In this conventional centrifugal pump, since the shaft sealing device 2 is located on the discharge side of the pump, the discharge pressure of the pump is applied to the sliding surface 2a of the shaft sealing device 2, and the atmospheric pressure side having a low pressure passes through the sliding surface. A very small amount of the pump handling liquid leaks to lubricate the sliding surface 2a with the small amount of liquid.

[Problems to be solved by the invention]

In the conventional centrifugal pump shown in FIG. 3, since the shaft sealing device is located on the discharge side, the original function of the mechanical seal, that is, lubrication of the sliding surface 2a with a small amount of liquid is alive and long-term operation is possible.

However, if air is mixed in the liquid handled by the pump for some reason, it will adversely affect the shaft sealing device even on the discharge side. The cause may be, for example, residual air in various spaces of pipes 11a and accessories such as a check valve (not shown), particularly an inverted U-shaped space, and a small amount of air leakage from a connection portion on the suction side. And suction of air from the liquid level when the tip of the suction pipe opens at a shallow position below the liquid level, and adheres to the impeller 5, guide blades 6 and the like at the pump itself at the time of start. It is the air that has been generated and is the gas generated by cavitation. As a result, the air and the like rotate together with the liquid 12 in the discharge chamber 8 in the rotation direction of the motor. As a result, the air having a low specific gravity stays near the axis as shown in the figure, and does not easily flow out of the discharge port 9 together with the liquid 12. Even if the air leaks to some extent, the above-mentioned air generation always occurs in a small amount, so that the shaft sealing device often remains constantly exposed to air. This means that there is no lubrication on the sliding surface of the shaft sealing device 2, and the life is shortened. And the frictional heat of the sliding surface further shortens the life. Further, from the viewpoint of the performance of the pump, the presence of compressible air in the discharge chamber 8 means that the expansion and compression of this air are repeated irregularly, which may cause instability of the pump operation and deterioration of the pump performance. Become.

As a solution, in the discharge casing 1a of FIG. 3, a cylindrical body surrounding the shaft sealing device is provided from the mounting surface at the upper end where the shaft sealing device 4 is mounted, and the impeller 5
It is also conceivable to form a casing in which a circular disc is extended to extend to the upper end again, leaving a discharge flow path. However, not only is the shape of the casing complicated, but also air accumulates in the cylinder surrounding the shaft sealing device, causing the same poor lubrication as described above. Although it is possible to provide a pipe for injecting pressurized water from the discharge channel into the cylindrical body, the structure becomes more complicated.

Thus, the present invention provides a pump sealing device provided on the discharge side which is always placed in a liquid to maintain good lubrication and cooling even if air is mixed into the handled liquid, and to improve the pump performance due to expansion and contraction of the residual air. The purpose is to prevent decline and instability.

[Means for solving the problem]

In order to achieve such an object, the present invention provides a vertical-shaft non-self-priming centrifugal pump of the type described at the beginning, in which a partition partitioning a discharge port and an impeller is provided in a discharge chamber, and a center of the partition is provided. A cylindrical portion is formed surrounding the shaft sealing device, and the inside thereof forms a communication port, so that the liquid flows around the shaft sealing device through the communication port toward the discharge port.

Further, in the centrifugal pump, a partition partitioning the discharge port and the impeller is provided in the discharge chamber, a number of small holes are provided as a communication port on the entire surface of the partition, and the liquid passes through the communication port to form a shaft sealing device. It flows around and goes to the discharge port.

[Action]

The partition wall has an action of preventing the high-speed rotation flow in the discharge chamber from being generated from the beginning, and the pump handling liquid always passes through a small hole provided inside the cylindrical portion formed in the partition wall as a communication port or on the entire surface of the partition wall, and the shaft sealing device. Flows around to the discharge port,
There is no air stagnation around the shaft sealing device, and the cooling and lubrication of the shaft sealing device are always properly performed.

〔Example〕

FIG. 1 is a sectional view showing a first embodiment of the present invention. In FIG. 1, components having the same functions as those in FIG. 3 are denoted by the same reference numerals. That is, an impeller 5 is attached to a shaft sealing device 2 provided at an upper end of a casing 1 composed of a discharge casing 1a and a suction casing 1b by penetrating a shaft 4, and a discharge chamber 8 is formed in an upper part of the casing 1 to form a discharge port. 9, a suction chamber 10 is formed in the lower part of the casing 1, and a suction port 11 is formed.
And an impeller 5 is provided with an inner casing 7 having a guide blade 6.
And driven by the motor 3.

In FIG. 1, the partition 42 divides the discharge chamber 8 in the axial direction. The partition 42 has a disk portion that divides the discharge chamber 8, and a central cylindrical portion surrounds the shaft sealing device 2 to form a communication port 43. Since the pump handling liquid discharged from the communication port 43 no longer generates a rotational flow in the discharge chamber 8 from the beginning,
There is no stagnation of air near the axis as in the conventional example. Therefore, the sliding surface of the shaft sealing device 2 is sufficiently lubricated and cooled.

FIG. 2 is a sectional view showing a second embodiment of the present invention. In FIG. 2, a large number of small holes 53 are provided over the entire surface of the partition wall 52 as communication ports.

Thus, the liquid discharged from the communication port 43 in FIG. 1 or the small hole 53 in FIG. 2 actively removes air that easily stays around the shaft sealing device.

〔The invention's effect〕

In the present invention, since the partition wall that separates the discharge port and the impeller is provided, there is an effect that the shaft sealing device always maintains good lubrication and cooling and has a long life even if air is mixed. Further, there is also an effect that the air retention is eliminated and the pump performance is maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view showing a second embodiment of the present invention, and FIG. 3 is a sectional view showing a conventional vertical shaft non-self-priming centrifugal pump. It is. DESCRIPTION OF SYMBOLS 1 ... Casing, 2 ... Shaft sealing device, 3 ... Motor, 5
... impeller, 6 ... guide blade, 8 ... discharge chamber, 9 ... discharge port, 11 ... suction port, 42 ... partition wall, 43 ... communication port, 52 ...
... partition walls, 53 ... small holes.

Claims (2)

(57) [Claims] 1. A discharge chamber is formed in an upper part of a casing, a discharge port is opened, and a shaft sealing device is provided at an upper end of the casing so as to be located in the discharge chamber. A motor shaft is passed through the shaft sealing device. An impeller is attached to a lower portion of a motor shaft extending below the discharge chamber, a suction port is opened in a lower portion of the casing, and the liquid sucked from the suction port is pressurized by the impeller to discharge the liquid. In a vertical-shaft non-self-priming centrifugal pump discharged from a discharge port of a chamber, a partition partitioning the discharge port and the impeller is provided in the discharge chamber, and the shaft sealing device is surrounded at the center of the partition and the inside thereof is formed. A vertical-shaft non-self-priming centrifugal pump, wherein a cylindrical portion forming a communication port is formed, and liquid flows through the communication port around the shaft sealing device toward the discharge port. 2. A discharge chamber is formed at an upper portion of a casing, a discharge port is opened, and a shaft sealing device is provided at an upper end of the casing so as to be located in the discharge chamber. A motor shaft is passed through the shaft sealing device. An impeller is attached to a lower portion of a motor shaft extending below the discharge chamber, a suction port is opened in a lower portion of the casing, and the liquid sucked from the suction port is pressurized by the impeller to discharge the liquid. In a vertical axis non-self-priming centrifugal pump discharged from a discharge port of a chamber, a partition partitioning the discharge port and the impeller is provided in the discharge chamber, and a number of small holes as communication ports are formed on the entire surface of the partition. A vertical-shaft non-self-priming centrifugal pump, wherein a liquid flows through the communication hole around the shaft sealing device toward the discharge port.