JPH0794837B2 - Centrifugal pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a centrifugal pump in which at least an impeller is made of synthetic resin, and particularly to an impeller and a liner ring slidingly contacting the impeller or a sliding contact portion of a liner ring portion. The present invention relates to an improved centrifugal pump.

[Background technology]

Conventionally, the components of the centrifugal pump casing and impeller are
Many are made by casting cast iron. However, the cast iron centrifugal pump has a problem in corrosion resistance, which causes red rust and rusting.

In order to avoid this, at least the impeller of the centrifugal pump may be made of plastic. If the centrifugal pump is configured in this way, corrosion resistance is improved, weight is reduced, and cost can be reduced.

FIG. 2 is a side sectional view of the essential parts showing the assembled state of the casing 7, the liner ring 2, and the impeller 3 in this type of centrifugal pump.

As shown in the figure, the casing 7 is cast from cast iron, and the casing 7 has a metallic annular liner ring 2
Is attached and fixed.

Further, the impeller 3 is formed of polyamide 66 (nylon 66), and the impeller suction port outer diameter 1 is fitted with a slight clearance so as to slidably contact the inner diameter of the liner ring 2.

[Problems to be Solved by the Invention]

By the way, the polyamide 66 (nylon 66) that constitutes the impeller 3 has a high water absorbency and a large swelling property.

FIG. 3 is an enlarged side cross-sectional view showing the positional relationship between the liner ring 2 and the impeller 3, and FIG. 3 (a) is before the impeller 3 swells (when the centrifugal pump is assembled) and FIG. 4] is a diagram showing after the impeller 3 has swollen (after passing a long time through a centrifugal pump for a long time).

As shown in the figure, when the centrifugal pump is assembled and its gap t3 is set to an optimum dimension, the impeller 3
When the swells, as shown in the figure (b),
As t3 disappears, the outer diameter 1 of the impeller suction port comes into full contact with the liner ring 2 or the state becomes a shrink fit. Therefore, there is a problem that the rotation of the impeller 3 is hindered and the outer diameter 1 of the impeller suction port is worn in a short period of time.

Then, in order to prevent this phenomenon, it is necessary to set the gap t3 to be large in consideration of the swelling amount of the impeller 3.

However, it takes a considerable amount of time for the impeller 3 to absorb water and completely swell. Therefore, if the gap t3 is increased, the gap until the impeller 3 is completely swollen.
There was a problem that leakage occurred from t3 and the original performance of the centrifugal pump could not be fully exhibited.

The present invention has been made in view of the above points, and a centrifugal pump capable of sufficiently exhibiting the original performance of the centrifugal pump when the impeller 3 is not swollen and when it is swollen. To provide.

[Means for Solving the Problems]

In order to solve the above problems, the present invention comprises at least the impeller made of a plastic material, and a part of the inner peripheral surface of the liner ring or the liner ring portion or one of the outer peripheral surfaces of the suction port outer diameter of the impeller. Before the swelling of the impeller, only a part of the facing surface of the both was directly in contact with the circumference, and a contact portion was provided to keep the airtightness.

[Action]

By configuring the centrifugal pump as described above, when the impeller is not swollen, the liner ring (or the liner ring portion) and the outer diameter of the impeller suction port are in contact with each other in a circumferential shape, Leakage does not occur between the two and the hermeticity of the pump is maintained.

On the other hand, when the impeller swells, the outer diameter of the impeller suction port outer diameter increases, but the contact resistance with the liner ring is small,
Not only does the impeller rotate with great resistance, and the contact portion is crushed and worn down, the resistance does not increase, and a proper gap can be finally formed.

Therefore, this centrifugal pump can maintain a proper gap between the outer diameter of the impeller inlet and the liner ring even when the impeller is not swollen or when the impeller is sufficiently swollen. The original performance of the centrifugal pump can be sufficiently exerted both at the time of starting and at the time of constant operation.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an enlarged side sectional view showing a positional relationship between a liner ring 2 and an impeller 3 of a centrifugal pump according to the present invention. FIG. 1 (a) is a first embodiment of the present invention, and FIG. Second embodiment, FIG. 7C is a diagram showing a third embodiment.

First, in the first embodiment of the present invention shown in FIG.
The outer peripheral surface of the impeller suction port outer diameter 1 of the impeller 3 is formed in a tapered shape with respect to the inner peripheral surface of the liner ring 2, and the impeller suction port outer diameter 1 contacts the liner ring 2 in the vicinity of its root portion. Is configured.

That is, the liner ring 2 is lightly contacted at its end with the outer circumference of the impeller suction port outer diameter 1 by one circumferential wire (contact portion 5).

With such a structure that the impeller suction port outer diameter 1 of the impeller 3 and the liner ring 2 are lightly contacted at the contact portion 5,
The hermeticity of the pump is maintained, and when the centrifugal pump is started, the pumping water does not get wet between the two, and the original performance of the centrifugal pump can be sufficiently exhibited.

Next, a centrifugal pump is used so that the impeller 3
Is swollen. At this time, since the liner ring 2 and the impeller suction port outer diameter 1 are in contact with each other only at the contact portion 5 formed by one circumferential line, the contact area is small. Therefore, even if the impeller 3 swells and the outer diameter of the impeller suction port outer diameter 1 increases, the contact resistance with the liner ring 2 is small, and the impeller 3 does not have a large resistance to rotate. .

Further, since the material of the impeller 3 is soft and the contact with the liner ring 2 is a line contact, when the outer diameter 1 of the impeller suction port is further expanded, the contact portion 5 portion of the outer diameter 1 of the impeller suction port is bent and worn down. By the way, the resistance does not increase.

Furthermore, the impeller suction port outer diameter 1 swells while buckling the contact portion 5 with the liner ring 2, and finally, FIG. 1 (a).
Expand to the position of the gap t2 shown in. This gap t2 is the optimum size as the gap between the liner ring 2 and the impeller suction port outer diameter 1. That is, the outer diameter of the impeller 3 may be designed to be small in advance so that when the impeller 3 swells, this dimension is finally obtained.

Therefore, there is no hindrance to the rotation of the impeller 3 after swelling,
The original performance of the centrifugal pump can be fully demonstrated.

Next, in the second embodiment shown in FIG. 1 (b), the outer diameter of only the root portion of the outer peripheral surface of the impeller suction port outer diameter 1 of the impeller 3 is increased so that the portion lightly contacts the liner ring 2. It is configured to touch.

Further, in the third embodiment shown in FIG. 1 (c), the outer peripheral surface of the impeller suction port outer diameter 1 of the impeller 3 is provided with screw-shaped irregularities, and the convex portions lightly contact the liner ring 2. It is configured to touch.

Even if the outer diameter 1 of the impeller suction port of the impeller 3 and the liner ring 2 are brought into contact with each other as in the second and third embodiments, the first
The same effect as in the case of the embodiment is produced.

That is, when the centrifugal pump is started, the liner ring 2
Since the outer diameter 1 of the impeller inlet of the impeller 3 and the outer diameter 1 of the impeller suction port of the impeller 3 are in contact with each other at the contact portion 5 in a circular shape (in the case of FIG. 6C, they are in contact with each other in a spiral shape), so that no leakage occurs between them and the sealing property of the pump is To be kept.

On the other hand, when the impeller 3 swells, the outer diameter of the impeller suction port outer diameter 1 increases, but the contact resistance between them is small,
Rotation of the impeller 3 does not give a great resistance, and the contact portion is crushed and worn away, so that the resistance does not become large and finally an appropriate gap t2 is formed.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to this, and various modifications such as the following are possible.

Needless to say, the material forming the impeller 3 is not limited to the polyamide 66, and other plastic materials may be used.

Further, in the centrifugal pump according to the present invention, it is not necessary that only the impeller 3 is made of a plastic material, and the casing 7
The liner ring 2 may also be made of a plastic material.

When the casing 7 and the liner ring 2 are made of the same plastic material, they may be integrated. At this time, the liner ring 2 does not become a separate part from the casing 7, and constitutes the liner ring portion as a part of the casing 7.

The shape of the outer peripheral surface of the impeller suction port outer diameter 1 is not limited to the above embodiment, and various modifications are possible.

Further, in the above embodiment, the shape of the outer peripheral surface of the impeller suction port outer diameter 1 is changed, but conversely, the shape may be changed by providing a taper on the inner peripheral surface of the liner ring 2. .

That is, the point is that the inner surface of the liner ring or the liner ring portion and the outer surface of the outer diameter of the suction port of the impeller face the facing surface, and only a part of the facing surface contacts in the circumferential direction. Any structure may be used as long as the contact portion is provided.

〔The invention's effect〕

As described in detail above, according to the centrifugal pump according to the present invention, even if the impeller is not swollen, the hermeticity between the outer diameter of the suction port of the impeller and the liner ring (or the liner ring portion) is improved. Can be maintained, and even after the impeller swells, an appropriate gap can be maintained between them. Therefore, the centrifugal pump has an excellent effect that the original performance of the centrifugal pump can be sufficiently exerted both at the time of starting the centrifugal pump and at the time of continuous operation.

[Brief description of drawings]

FIG. 1 is an enlarged side sectional view showing a positional relationship between a liner ring 2 and an impeller 3 of a centrifugal pump according to the present invention. FIG. 1 (a) is a first embodiment of the present invention, and FIG. 2nd Example, the same figure (c) is a figure which shows 3rd Example, FIG. 2 is a principal part side sectional view which shows the assembly state of the casing 7, liner ring 2, and impeller 3 of a centrifugal pump, FIG. FIG. 3 is an enlarged side cross-sectional view showing a positional relationship between a conventional liner ring 2 and an impeller 3, FIG. 1A shows a state before the impeller 3 swells, and FIG. 2B shows a state after the impeller 3 swells. FIG. In the figure, 1 ...... impeller suction port outer diameter, 2 ...... liner ring,
3 ... impeller, 5 ... contact part, 7 ... casing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-114899 (JP, A) Actual-open Sho-48-70101 (JP, U) Actual-open Sho-53-165302 (JP, U) Actual-open Sho-63- 36693 (JP, U) Suke 38-28157 (JP, Y1)

Claims (2)

[Claims] 1. A casing and an impeller, wherein an outer peripheral surface of an outer diameter of a suction port of the impeller is rotatably housed in a liner ring attached to the casing or an inner peripheral surface of a liner ring portion integrated with the casing. In a centrifugal pump having a structure, at least the impeller is made of a plastic material, and a part of an inner peripheral surface of the liner ring or a liner ring portion or a part of an outer peripheral surface of an outer diameter of a suction port of the impeller,
A centrifugal pump, characterized in that, before swelling of the impeller, only a part of the opposing surfaces of the two impinges directly on the circumference and is provided with a contact portion for maintaining its airtightness. 2. A taper, a large-diameter portion, or a screw-shaped projection is provided on the outer peripheral surface of the suction port outer diameter of the impeller, and the taper, the large-diameter portion, or the projection is formed on the liner ring or the liner before the impeller swells. The centrifugal pump according to claim 1, wherein the inner peripheral surface of the ring portion is directly contacted circumferentially.