JP2728467B2 - Vertical pump with suction side self-priming chamber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a technique for providing a self-priming chamber on the suction side of a centrifugal pump in order to provide the centrifugal pump with a self-priming function. Related.

[Conventional technology]

An outline of the self-priming function, types of the self-priming method, and a conventional technique of the high-lift pump will be described.

a) Since the suction pressure of the centrifugal pump reaches the suction pipe in the normal operation state, it is logically about 10 m below the pump according to the Trichielli principle, and actually 5 to 8 m due to cavitation and the like.
Can absorb water from the water surface. When the pump starts operation from an empty state, the suction pressure becomes substantially zero and water cannot be absorbed.Therefore, a check valve is provided in the suction pipe, a large amount of water is primed to the entire suction pipe, and the pump is started. You.

b) Non-return valves have a cause of failure, and a large amount of priming water is difficult, and may be required every time the pump is stopped. In the self-priming type, a device provided with a steam-water separation chamber on the discharge side is often used, for example, as shown in JP-B-57-44835 and JP-B-59-48319. This ensures that water remains in the impeller chamber and the air / water separation chamber even when the pump stops, and that the water level in the suction pipe gradually rises with the suction pressure of the pump during the self-priming operation, and only air in the air / water separation chamber And return water to the impeller chamber to continue self-priming. At this time, since the impeller mixes water and air, a centrifugal pump that generates a head in proportion to the density of the handled fluid has a small flow rate and suction pressure, depending on the length and thickness of the suction pipe and the quality of the self-priming function. Normally, self-priming is completed within several minutes to 10 minutes, that is, the water level in the suction pipe reaches the pump, and normal operation is started.

This discharge side water-water separation chamber type self-priming pump requires only a small amount of priming water only at the first time after installation or for a long time after the operation of the water-water separation chamber is evaporated and the water is re-operated. It is convenient because it starts normal operation. However, there is a property that the self-priming time always exists. Therefore, in a coolant pump that sends a grinding fluid or a cutting fluid to a machine tool, there is a possibility that a blade or the like may seize within the self-priming time.

c) On the other hand, pumps of the suction side self-priming chamber type are often used, for example, those disclosed in Japanese Patent Application Laid-Open No. Sho 56-110593 and Japanese Utility Model Application Laid-Open No. Sho 56-165996.
2 (1970) Self-priming type of "coolant pump". The suction side self-priming chamber type pump has no self-priming time in principle. Since the above document does not explain this principle, the main points of this principle will be described below.

The basic structure of the suction-side self-priming chamber type pump is such that an inlet of an impeller chamber for storing a centrifugal impeller is arranged upward, and a suction-side self-suction chamber communicating with the upper part of the impeller chamber through the inlet is provided. A suction port of the pump is formed above the suction-side self-priming chamber, and a discharge flow path communicating with the outlet of the impeller chamber is provided upward, and a discharge port of the pump is formed at the upper end thereof. No check valve is required.

When the pump stops and the tip of the discharge pipe is open to the atmosphere, the water communicating with the discharge pipe, the pump, the suction pipe, and the water storage tank flows backward. In the pump, a discharge port, a discharge flow path, an impeller chamber, a suction-side self-priming chamber, and a water passage communicating with the suction port are U-shaped. Therefore, when the water surface in the discharge pipe descends to the lower end of the discharge flow path, the so-called siphon is cut off, and only air flows backward through the impeller chamber, the suction-side self-priming chamber, and the suction port into the reverse flow pipe. . The water surface generated in the suction pipe descends, reaches near the water surface of the water storage tank, balances, and the backflow stops. During this time, most of the water in the suction-side self-priming chamber and the impeller chamber remains.

When the pump is restarted, the impeller filled with water instantaneously exhibits the normal pumping action to pump water into the discharge pipe, and the water level in the suction pipe rises. Instant self-priming. This continues until the air in the upper part of the suction-side self-priming chamber increases and its water level drops and becomes empty. If the water in the suction pipe reaches the suction-side self-supply chamber by that time, the water falls in this chamber, continuously supplies water to the impeller chamber, and the pump continues to operate normally. The basic condition that the suction-side self-priming chamber does not become empty is that the volume of the suction-side self-priming chamber is the internal volume of the suction pipe (tube cross-sectional area ×
Length). The air that accumulates in the upper part of the suction-side self-priming chamber gradually mixes with water during normal operation and is discharged.However, this does not significantly reduce the density of the fluid handled in the impeller, and the above-mentioned discharge-side gas-water separation chamber There is no significant decrease such as a decrease in flow rate and head during self-priming.

d) JP-B-59-44518 and JP-A-60-128997 are examples of vertical multi-stage centrifugal pumps and are non-self-priming types. To increase the diameter of the impeller in order to obtain a high head, there is a limit due to the specific speed and the like, so that the impeller is configured in multiple stages. There is no restriction on specific speed,
In some cases, the diameter of the impeller is reduced and the number of stages is increased, so that the installation floor area of the vertical shaft pump is advantageous. In each of the above documents, the inlet of the multi-stage impeller chamber is arranged downward, and a suction port is provided at the lower part of the pump. The latter is simply provided at the upper part of the pump in the latter, whereas the former is provided with the outlet by guiding from the upper part to the lower part in the return passage. In any case, even if something like a suction side self-priming chamber is added to the suction side, as can be seen from the above-mentioned principle of operation of the suction side self-priming chamber, the suction side self-priming function cannot be exhibited, and the discharge side gas-water separation chamber is not provided. It is conceivable to add this to improve the self-priming type.

[Problems to be solved by the invention]

To summarize the above prior art: a) The non-self-priming type has no problem when the water level of the water reservoir on the suction side is higher or lower than that of the pump when almost continuous operation is performed. However, when the water level is lower than that of the pump, there is a cause of failure of the check valve, and a large amount of priming water is required every time the pump is restarted.

b) If the discharge side gas-water separation chamber type is within the maximum suction head of the pump, self-priming is easily performed with a small amount of priming water and normal operation is started. Applications It is not suitable for use, for example, for transferring coolant liquids for industrial machines.

c) Suction pipe volume (tube cross-sectional area x length) for suction side self-priming chamber type
There is a limit, but self-priming at the moment.

d) When a high-lift multistage pump is of a self-priming type, a discharge side steam-water separation chamber type can be applied, but it is difficult to apply to a suction side self-priming chamber type.

It is an object of the present invention to provide a pump having a small installation floor area and a high head, and capable of instantaneously self-priming from a suction water surface lower than the pump.

[Means for solving the problem]

According to the present invention, a plurality of impeller chambers which accommodate centrifugal impellers, and whose inlets are arranged upward and are connected in multiple stages, are provided at the top of the impeller chambers. An annular shape formed by a suction-side self-priming chamber communicating with the inlet of the impeller chamber, a pump suction port formed above the suction-side self-priming chamber, and an outer casing surrounding the outside of the plurality of impeller chambers. A flow path, a discharge flow path provided upward and communicating with the annular flow path, and a discharge port of a pump formed at an upper end of the discharge flow path; This is achieved by making the suction side self-priming chamber communicate with the outlet and the annular flow path and the discharge flow path.

[Action]

1) Suction port 8, suction side self-priming chamber 11, multi-stage impeller room 5m, 5
n, the annular flow path 12, the discharge flow path 10 (10a, 10b, 10c, 10d) and the discharge port 9 communicate in a U-shape. In this U-shaped flow path, the suction port 8 and the discharge port 9 are U-shaped. The start and end of the U-shape, and the exit 5h of the impeller chamber 5n is the lower end of the U-shape (corresponding to all drawings).

Such a configuration has the function of a suction-side self-priming chamber type pump although it has multiple stages. Therefore, when the pump is restarted after stopping without providing a check valve for the suction pipe, the pump automatically self-primes from the suction water surface lower than the pump and discharges the original flow rate of the pump, and there is no self-priming time. However, it is outside the problem of this technique that when the discharge pipe is empty, the pump fills the inside of the discharge pipe with water and then the water comes out from the tip. The time is also extremely short in principle compared to the discharge side steam-water separation chamber type. Although there are multiple stages, the impeller chamber is surrounded by the outer casing 7 so that even if there is leakage from the joint surface of the impeller chamber, water does not leak out of the pump.
Since the annular flow path 12 is located on almost the entire circumference, even if the dimension in the radial direction is small, the fluid resistance is not small, and the floor area for installing the pump can be reduced.

2) The installation floor area can be further reduced by making the discharge passage 10 project inward from the outer diameter of the impeller to make the suction-side self-priming chamber slightly higher (corresponding to FIGS. 1 and 2).

〔Example〕

FIGS. 1 and 2, FIGS. 3 and 4, FIGS. 5 and 6, FIGS. 7 and 8, and FIGS. 9 and 10 are different from FIGS. An example will be described.

1 and 2, the drive motor shaft 2 penetrates through the wall of a self-priming chamber casing 1 forming a suction-side self-priming chamber 11 through a shaft sealing device 2a such as a mechanical seal. Cars 3 and 3a are fixed with bolts 4. Each impeller is formed by the inner casing 5, 5a, and the inlet 5g is directed upward.
Are stored in the impeller chambers 5m and 5n having the outlet 5h downward and connected in multiple stages. An outer casing 7 surrounding these impeller chambers 5m and 5n and having a flange 6 for installing a pump supports the inner casing 5a by a projection 7a provided continuously on the circumference of the inner lower surface thereof. On the other hand, the upper end of the outer casing 7 is in liquid-tight contact with the self-priming chamber casing 1 via an O-ring 13 and is fixed by bolts 13a. Thus, impeller room 5
An annular flow path 12 is formed between m and 5n and the outer casing 7, and this annular flow path 12 communicates with the outlet of the lowermost impeller chamber 5a through the intermittent projections 7a.

As can be seen from FIG. 2, the self-priming chamber casing 1 has a portion 1a on the circumference projecting from the outer diameter of the impeller chamber 5m toward the axis. In other words, a part of the upper part of the annular flow path 12 on the circumference protrudes toward the axis, and the discharge port 9 communicates with the upper part.
On the other hand, the self-priming chamber casing 1 is provided with a suction port 8 communicating with the suction-side self-priming chamber 11.

After all, the suction port 8, the suction side self-priming chamber 11, the multi-stage impeller chamber 5
m, 5n, the annular flow path 12, the discharge flow path 10, and the discharge port 8 communicate in a U-shape. In this U-shaped flow path, the suction port 8 and the discharge port 9 become the start and end of the U-shape, and the outlet 5h of the impeller chamber 5n.
Is the lower end of the U-shape. Even when the pump is stopped and water flows backward from a discharge pipe (not shown) connected to the discharge port 9, when the water surface in the discharge pipe reaches the lower end of the U-shape, the so-called siphon is cut off, and air flows from this lower end, that is, the outlet 5h. The water in the impeller chambers 5m and 5n and the suction-side self-priming chamber 11 no longer flows backward when sucked into the suction side.

Since the annular flow path 12 is located on the entire circumference, the radial dimension may be small, and since the discharge flow path 10 protrudes from the axis, the maximum diameter of the pump, that is, the installation floor area is reduced. Since the joint surfaces of the inner casings 5 and 5a, which are formed due to the multi-stage formation, are surrounded by the outer casing 7, if only the O-ring 13 is liquid-tightly treated, the liquid leaks from the entire pump. Does not pollute the outside. At the same time, the external casing 7 receives external force and does not reach the inner casings 5 and 5a, so that the strength of the inner casing is small. Since the multi-stage pump has extremely flat impellers and inner casings in terms of specific speed, it is possible to pursue liquid dimensions and shapes, which is useful for improving pump efficiency.

A modification of this embodiment will be described. The drive may be provided below the pump. If the bolt hole 6a portion of the flange 6 is projected toward the axis at the projection 7a, the installation floor area is further reduced. At this time, the annular channel 12 is divided on the circumference, but the annular channel 12 is continuous above the projection 7a. Impeller room 5, 5a
The outer casing may be eccentrically inscribed instead of concentrically, and the inner contact may be located on the opposite side of the discharge flow path 10.

3 and 4 showing the second embodiment, those denoted by the same reference numerals as those in FIG. 1 have substantially the same functions. The larger the outer diameters of the self-priming chamber casing 31 and the outer casing 37, the larger the cross-sectional area of the annular flow path 12 is. Therefore, the protrusion 31a facing the axis of the self-priming chamber casing 31 is close to the outer diameter of the impeller 5m, and the volume can be increased without increasing the height of the suction-side self-priming chamber 11. That is, it is suitable for a thick and long suction pipe. Since the self-priming chamber casing 31 is larger than the impeller chambers 5m and 5n, a disc 30 that connects the two is provided, and the disc 30 is provided with a notch 30a that connects the annular flow path 12 and the discharge flow path 10.

In FIGS. 5 and 6 showing the third embodiment and FIGS. 7 and 8 showing the fourth embodiment, the discharge passage 10 is formed outside the annular self-priming chamber casing 51 or 71. A discharge flow path is provided outside the annular outer casing 57 or 77 facing this.
10a is formed. When the self-priming casing 51 or 71 and the outer casing 57 or 77 are opposed to each other in a liquid-tight manner, the two discharge passages 10 and 10a become an integral discharge passage. In the third embodiment, the O-rings 52 and the O-ring 53 for making the liquid-tightness of the O-rings 52, 10 and 10a are separate parts in the liquid-tight contact. The difference is that the ball-shaped flat packing 72 makes the liquid tight at once.

In FIGS. 9 and 10 showing the fifth embodiment, a discharge passage 10a is formed outside an annular outer casing 97, and a pipe 10c and an elbow 10d are connected to a pipe screw 10b at the distal end thereof. 9 is formed, and the external piping 99 can be connected. Therefore, the outside of the self-priming chamber casing 91 is annular.

As a modification of the fifth embodiment, the pipes up to the discharge flow path 10a provided with the pipe thread 10b may be produced in a factory and used at the installation site of the pump by piping as shown in FIG. It is also within the scope of the present invention to provide a connection port through which an external pipe can be directly provided in the annular outer casing forming the annular flow path 12, and to provide a pipe corresponding to FIG. 9 to this connection port.

〔The invention's effect〕

This invention communicates the suction port, the suction side self-priming chamber, the multi-stage impeller chamber, the annular flow path, the discharge flow path and the discharge port in a U-shape,
In this U-shaped flow path, the suction port and the discharge port are the start and end of the U-shape, the outlet of the lowermost impeller chamber is at the lower end of the U-shape, and the outer casing further surrounds the impeller chamber. Since the annular flow path is formed in the multi-stage, it has the function of a suction side self-priming chamber type pump even though it is multi-stage, and has the effect of being a so-called momentary self-priming type without self-priming time. There is the effect that water leakage from a large number of connection surfaces of the chamber can be prevented only at one contact surface between the outer casing and the suction-side self-priming chamber. Therefore, the flat impeller and the impeller chamber are free from the mounting strength and water leakage countermeasures for high lift,
The effect is that you can concentrate only on the pursuit of pump characteristics,
The annular flow path having a small liquid resistance has the effect of reducing the installation floor area. The floor area can be further reduced by projecting the discharge passage inward from the outer diameter of the impeller chamber (FIGS. 1 and 2).

[Brief description of the drawings]

1 is a sectional view of the embodiment, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is a sectional view of the second embodiment, and FIG.
5 is a cross-sectional view of the third embodiment, FIG. 6 is a cross-sectional view of VI-VI of FIG. 5, FIG. 7 is a cross-sectional view of the fourth embodiment, 8 is a sectional view taken along line VII-VII of FIG. 7, FIG. 9 is a sectional view of the fifth embodiment, and FIG. 10 is a sectional view taken along line XX of FIG. 1,31,51,71,91 …… Self-priming chamber casing, 2 …… Shaft, 3,3
a… impeller, 5,5a… inner casing, 5g… entrance, 5h
… Exit, 5m, 5n… Impeller room, 7, 37, 57, 77, 97… Outer casing, 10, 10a… Discharge channel, 11… Suction side self-priming chamber,
12: annular flow path, 30: disk.

Claims (1)

(57) [Claims] 1. A plurality of impeller chambers accommodating a centrifugal impeller and having inlets arranged upward and connected in multiple stages, and communicating with an inlet of an uppermost impeller chamber provided above the impeller chamber. A suction-side self-priming chamber, a suction port of a pump formed above the suction-side self-priming chamber, and an annular flow path formed by an outer casing surrounding the outside of the plurality of impeller chambers. A discharge flow path communicating with the annular flow path, and a discharge port of a pump formed at an upper end of the discharge flow path. The annular flow path communicates with an outlet of a lowermost impeller chamber, and A vertical pump of a suction side self-priming chamber type, wherein the side self-priming chamber is not communicated with the annular flow path and the discharge flow path.