JPS5824639B2 - vortex pump impeller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impeller for a portex pump.

The Portex pump has an impeller with nearly radial blades spaced apart from the casing by a relatively large distance, which prevents the pump from clogging when there is foreign matter in the pumped liquid, and therefore prevents the pump from clogging. It is often used for processing.

In order to prevent such foreign objects, according to the prior art, the gap between the impeller and the pump casing is increased, the number of blades of the impeller is reduced, and the width of the blades is increased. , or the impeller was recessed away from the pump casing.

However, although this conventional technology solves the problem of pump clogging due to foreign objects, the impeller width and casing area become larger than necessary, resulting in a significant increase in water volume, which often results in overheating of the electric motor or prime mover. It was causing a load.

The present invention was invented in order to eliminate these drawbacks, and its purpose is to prevent the pump from clogging due to objects in the pumping liquid, and to ensure that the pump characteristics are compatible with the electric motor and prime mover at any water volume. An object of the present invention is to provide an impeller for a portex pump that does not cause overload.

For this purpose, the impeller of the portex pump according to the present invention is provided with a distance from the pump casing that allows foreign matter to pass through.
The impeller consists of a main plate and blades attached to the main plate and extending in the axial direction.The blades are curved from the suction side to the outlet side, and the spacing between the blades is equal to the distance between adjacent blades. When inscribed circles touching the blade are drawn, the diameters of the inscribed circles are small on the suction side, large between the suction side and the outlet side, and small again on the outlet side.

Before explaining the present invention, general matters regarding pump characteristics will first be explained.

There are various factors that control the characteristics of a pump, but
From the conventionally known concept, water volume Q due to specific speed NS
- Lifting head characteristics and water volume Q) - Power (KW) characteristics are shown in Fig. 1 A9.

Figure 1a. As shown in the figure, it can be seen that the power curve of the medium specific speed pump does not exceed the rated value at any water flow rate than the low specific speed pump.

Figure 2 shows the amount of water (Q - head (I()%) depending on the impeller exit angle.
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As shown in FIG. 2, it can be seen that the water displacement-head characteristic with a small impeller exit angle has a large slope, and the slope of the kneading property with a large impeller exit angle is small.

Therefore, as the amount of water permeated with a small impeller exit angle increases, the rate of reduction in head increases.

Further, the pump shaft power PKW is expressed as a value obtained by dividing the product of water volume, head, and pumped liquid specific gravity by pump efficiency, as shown in equation (1).

PKW=0.163γQH/η ・・・・・・・・・
・・・・・・・・・・・・(1) γ unit volume weight (kg/
m') Q - Water volume (m''/mvr) H - Head (m) η - Pump efficiency Based on this concept, when determining the dimensions of the pump casing and impeller, the specific speed NS is N- Number of rotations (r
pm) H - Head (m) Q - Water volume (m'/myr) From formula (2), to increase NS, high speed rotation, large water volume,
It can be seen that it is sufficient to design with a low head.

Now, when designing a pump, as can be seen from the beginning of Figure 1, it is preferable to have a medium specific speed NS from the viewpoint of shaft power.If the specific speed NS is small, the shaft power will be low due to large water flow, and the specific speed NS If is large, the shaft power will be large (becomes) when tightening (when the amount of water is zero).

On the other hand, in order to increase the lift height, the blades must have a diffuser effect, and as shown in Fig. 3 A2, in the conventional impeller, the blades 1'a, 1'b... The inscribed circle A'1. which touches the blades 1'a, 1'b in the adjacent blades 1'a, i'b with an interval of . If A2 + A'3 is drawn, the inscribed circle A/1° Al1. The diameter of Al1 is smallest on the suction side 2, gradually increases toward the outlet side 3', and becomes largest on the outlet side 3'.

However, in this conventional impeller, the outlet side 3'
Since it is open, the amount of water inevitably becomes large compared to the head, NS decreases, and the shaft horsepower becomes too large when the amount of water is large.

To do this, the outlet side 3' should be slightly narrowed down, but since the flow path of the impeller is formed almost radially, simply
If ′ is narrowed, the adjacent flow path will open up.

Therefore, in the present invention, the exit angle β2 of the impeller is made small to narrow the exit side a little, and as can be seen from FIG. Shaft horsepower can be limited during large amounts of water, and shaft horsepower does not increase even when the water is closed.

Figure 4A5 shows an impeller embodying the present invention.

In FIG. 4, the blades 1a, 1b, .

When inscribed circles A4, A2, and A3 that touch 1b are drawn, the diameters of the inscribed circles A1 s A2 and A3 are small on the suction side 2, large between the suction side 2 and the outlet side 3, and small again on the outlet side 3. There is.

With this configuration, the outlet side 3 of the impeller is throttled, so the outlet angle β2 becomes small, the shaft horsepower becomes small when the amount of water is large, and the amount of water is also limited by the throttle on the outlet side 3.

The squeezed water volume is converted into pressure energy or head.

A pump with a conventional impeller shown in Fig. 3 A and the 4th port.
5 and 6 show the differences in characteristics from the pump equipped with the impeller according to the present invention shown in FIG.

These figures conceptually illustrate the characteristics.

In the conventional impeller shown in Fig. 3 A with 2 ports, the inlet inscribed circle A
/1 is determined so that filth or solids can pass through, and as it continues toward the exit, the inscribed circle becomes A'2, A'
As shown in Figure 5, it becomes larger as shown in Figure 3.
If the amount of water increases, the rated power value will be exceeded.

When this pump is used as a drainage pump, the pump operating point will shift due to the water level drop due to drainage, and the actual pump head will be small at the beginning of drainage, so a large amount of water will be produced, so the electric motor will be operated with overload, and in the worst case, the thermal relay Protective devices such as these are activated, the electric motor stops, and the pump stops draining.

In order to prevent this from happening, the motor must have a high output in order to drain the water with sufficient margin, which increases equipment costs.

However, in the present invention, as shown in FIG. 4A, the blades of the impeller have a shape that is curved from the suction side to the outlet side, and the interval between the blades is such that the interval between adjacent blades is such that there is an inscribed contact between adjacent blades. When a circle is drawn, the diameter of the inscribed circle is small on the suction and reverse side, large between the suction and outlet sides, and small again on the outlet side, so the water volume is constricted when there is a large amount of water, and the exit angle is small. As a result, the shaft horsepower can be reduced below the rated power value as shown in FIG.

That is, according to the present invention, the slope of the shaft horsepower becomes flat as the amount of water increases.

Therefore, according to the present invention, no amount of water exceeds the rated power value.

Therefore, there is no need to use a particularly high-output electric motor in consideration of the pump's drainage function stopping, as is the case in the past, and therefore equipment costs can be reduced accordingly.

Furthermore, since the rated power value is not exceeded at any water volume, it is suitable for equipment that cannot handle pulp operations. This characteristic is particularly exhibited in the following.

When implementing the present invention, the diameter of the inscribed circle A3 is the diameter of the inscribed circle A2
It is sufficient to make the diameter slightly smaller, but not much smaller than the diameter.

[Brief explanation of the drawing]

Figure 1A is a graph showing the water volume-head characteristics of the pump depending on the specific speed, Figure 1 is a graph showing the water volume-power characteristics of the pump depending on the specific speed, and Figure 2 is the graph showing the water volume-head characteristics depending on the impeller outlet angle. The graph shown in Fig. 3A is a plan view of the impeller used in the conventional portex pump, and the cross-sectional view is shown in Fig. 4A. The port is a plan view and a sectional view of the impeller according to the present invention, FIG. 5 is a graph showing the pump characteristics of a pump equipped with a conventional impeller shown in FIG. It is a graph conceptually showing the pump characteristics of a pump equipped with an impeller according to the present invention shown in two ports. 1a, 1b...impeller blades, 2...suction side, 3...exit side.

Claims (1)

[Claims] 1. In the impeller of a portex pump, which is installed at a distance from the pump casing that allows foreign matter to pass through, the impeller consists of a main plate and a blade attached to the main plate and extending in the axial direction. It has a shape that is curved from the suction side to the outlet side, and when an inscribed circle is drawn that touches the blades between adjacent blades, the diameter of the inscribed circle is smaller on the suction side and the diameter of the inscribed circle is smaller on the suction side and the outlet side. The impeller of the portex pump is characterized by a different spacing, which is larger in the middle of the sides and smaller again on the outlet side.