JPH094585A - Sewage pump - Google Patents

Abstract

PURPOSE: To provide a non-blocking sewage pump whose pump efficiency is not reduced too much and whose vibration is small. CONSTITUTION: In a sewage pump provided with a protector 4 on the inner surface of a casing 3 opposite to blades 2 of an impeller 1, a spiral groove 5 leading to an outlet side from an inlet side of the impeller is formed on the inner circumferential surface of the protector along the rotational direction of the impeller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage pump, and more particularly to a non-blocking sewage pump for pumping sewage containing foreign matter.

[0002]

2. Description of the Related Art Conventionally, in the sewage pump, in order to allow foreign matter to pass through the impeller blade and the protector provided on the inner surface of the casing opposed to the impeller, the foreign matter is passed through the gap between the protector and the blade. Attach a cutter to a larger one (more than twice as large as a normal pump) or an impeller,
It has been proposed that the foreign matter sandwiched between the edge of the blade and the protector be finely cut so as to pass through the gap between the blade and the protector.

[0003]

However, increasing the clearance between the protector and the blade causes leakage loss due to the secondary flow from this clearance, and the pump efficiency decreases as shown in FIG. 4B. . On the other hand, in the case where the impeller is provided with a cutter, the edge of the cutter is worn by solid matter such as earth and sand in the pumped water due to long-term use, and not only its function deteriorates, but also vibration and noise are generated when cutting foreign matter. Has the problem. An object of the present invention is to provide a sewage pump that does not significantly reduce pump efficiency, does not deteriorate foreign matter removal function for a long period of time, and does not generate vibration or noise.

[0004]

In order to achieve the above object, the present invention provides, in the invention of claim 1, a sewage pump provided with a protector on an inner surface of a casing facing an impeller blade. A spiral groove extending from the inlet side to the outlet side of the impeller is formed on the circumferential surface along the rotation direction of the impeller. In the invention of claim 2, the spiral groove has a plurality of threads, and the size and shape of each groove are different.

[0005]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In FIG. 1, reference numeral 1 is an impeller of a mixed flow pump attached to a rotary shaft 3, and its blades 2 are pump casings 3.
It is located with a gap a in the normal pump and the protector 4 provided on the inner surface of the. This gap a is about 0.6 mm when the pump outlet diameter is 300 mm, but increases with the pump outlet diameter. Then, as shown in FIG. 2, a spiral groove having an angle α with respect to the rotation direction of the impeller 1 and extending from the inlet side to the outlet side of the impeller on the inner peripheral surface of the protector 4 facing the blade 2. A plurality of 5 are provided. The spiral groove 5 has a width of 3 mm and a depth of 2 mm, for example.

Due to the above structure, during pump driving,
Even if the foreign matter S, which is slightly larger than the gap a, reaches the gap a,
As shown in FIG. 3, a part thereof enters the spiral groove 5, and the foreign matter S is pushed into the spiral groove 5 in the rotational direction by the tip of the blade 2 based on the rotation of the impeller 1 and is moved into the spiral groove 5. The liquid is discharged while moving in the gap a. Moreover, since the pumped water also flows in the spiral groove 5 toward the outlet due to the rotation of the impeller 1, the decrease in pump efficiency is small as shown in FIG.

The spiral groove 5 is not limited to one kind in shape and size, but various kinds of shapes and sizes are used to form a multi-row spiral groove, and foreign matter is spiraled according to its shape and size. It may be discharged from the groove. In FIG. 3, the spiral groove in FIG. 1 and a triangular groove having a width of 2 mm and a depth of 2 mm are used.

Further, the waste water pump is not limited to the mixed flow pump shown in the above embodiment, but can be applied to a pump provided with an open type impeller or an axial flow pump.

[0009]

As is apparent from the above description, according to the present invention, the protector and the blade of the impeller are made the same as before without increasing the gap between them, and the inner peripheral surface of the protector is arranged along the rotating direction of the impeller. Since the spiral groove extending from the inlet side to the outlet side of the impeller is formed, foreign matter larger than the gap is also discharged through the spiral groove and the gap by the rotation of the blade. Moreover, without increasing the gap between the protector and the blade of the impeller,
Moreover, since pumped water is also discharged outward from the spiral groove, the decrease in pump efficiency is extremely small.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of a sewage pump according to the present invention.

FIG. 2 is a front view of the protector showing the shape of the spiral groove.

FIG. 3 is a diagram showing a modification of FIG. 1 and a passing state of foreign matter.

FIG. 4 is a graph showing the relationship between the flow rate, total head and pump efficiency in the present invention and the conventional example.

[Explanation of symbols]

1 ... Impeller, 2 ... Blade, 3 ... Pump casing, 4 ... Protector, 5 ... Spiral groove.

Claims (2)

[Claims] 1. A sewage pump having a protector on an inner surface of a casing facing an impeller blade, wherein a spiral extending from an inlet side of the impeller to an outlet side of the inner peripheral surface of the protector along a rotation direction of the impeller. A sewage pump characterized by having a groove formed. 2. The wastewater pump according to claim 1, wherein the spiral groove has a plurality of threads, and the size and shape of the grooves are different.