JPH0441999A - Jet pump - Google Patents

Abstract

PURPOSE:To prevent lock due to solid matters and decrease of pump discharge due to arrangement of an air inlet pipe by providing two tubes having the same internal diameter, and by attaching a driving flow pipe to an annular tapered aperture, which makes inner and outer walls of the intersecting points of the tubes and the plural cones which have the same axis as the tubes. CONSTITUTION:An external thread 1a is provided on an outside surface of a rear half part of an inner tube 1 having a uniform inside diameter. A front end 1b of this inner tube 1 is a conical surface, which is co-axial with the inner tube 1 and reduces its diameter toward its front end. On the other hand, on the rear end of an outer tube 2, an internal thread 2a is provided for engaging with the above-mentioned external thread 1a, and also a bearing nut 3 is screwed to prevent looseness between the inner tube 1 and the outer tube 2. Furthermore, the front part of the outer tube 2 is formed so as to have almost the same internal diameter as that of the inner tube 1, and a front end 2b of the inner surface at the middle portion of the outer tube 2 is formed so as to be a cone which is co-axial with the outer tube 2 and reduces its diameter toward the front end.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a jet pump, and particularly to a jet pump suitable for conveying a fluid containing solids.

``Problems to be solved by the prior art and the invention 1 Conventionally, jet pumps have a driving flow piping 5, as shown in Fig. 2.
In the center flow jet pump, the flow path 6b of the driven flow piping 6 is annular because the flow path 6b of the driven flow piping 6 is arranged coaxially inside the driven flow piping 6. is generally formed in a circular shape, so if the flow path cross-sectional area of the driven flow pipe 6 from the inlet end 6a to the annular flow path 6b of the die pump section is made the same, a sphere that can just pass through the inlet end 6a. is the annular flow path 6 of the jet pump section
b.Therefore, when the object to be conveyed contains solids, such as in a sand pump for a sand settling basin, there is a risk of blockage of the pump. In addition, since there is a strong risk of cavitation occurring in this central flow jet pump, it is generally necessary to blow air to prevent cavitation from occurring.On the other hand, there is the problem that blowing air reduces the pumping amount of the driven flow. It also had

Further, Japanese Patent Publication No. 63-25200 discloses a jet pump that ejects a driving flow from a number of nozzles provided on the outer periphery of the terminal end of a driven flow pipe.

In this configuration, the cross-sectional area of the flow passage expands in a stepwise manner at the end of the driven flow piping, that is, at the beginning of the mixing region of the driving flow and the driven flow, but in order to increase the efficiency of the jet pump, generally It is necessary to narrow down the expanded mixing area,
If the pipe diameter is narrowed, there is a risk that the flow path will be blocked by solid matter at that part6.Furthermore, although this technology has a structure in which a number of central flow jet pumps are arranged in a ring, it is difficult to connect the air introduction pipe. However, as a result, the amount of pumped water is inevitably reduced, and the above-mentioned problems in the central flow jet pump have not been solved.Therefore, the present invention is directed to It is an object of the present invention to provide a jet pump that has no risk of clogging due to solid matter during conveyance, does not require the provision of an air introduction pipe, and therefore does not cause a decrease in pumped water.6 [Problems solved] [Means for achieving the above object] The present invention has been made to achieve the above object, that is, a pipe having substantially the same inner diameter is provided, and first and second conical shapes sharing an axis with the pipe are provided. In this jet pump, an annular tapered opening is provided in the piping and a driving flow piping is attached to the opening, the inner wall and the outer wall being the positions where the piping intersects with the piping.

[Operation] The driven flow piping, that is, the piping before the part where the opening is provided,
Since the mixing region, that is, the piping after the opening is formed to have substantially the same inner diameter, there is no risk of blockage due to solids even when transporting a fluid containing solids. Further, according to the experimental results according to one embodiment of the present invention, cavitation did not occur at all even without blowing air. The reason for this is, firstly, that the piping has no expanding or decreasing diameter portions, and secondly, since both the inner and outer walls forming the opening are formed in a conical shape, the driving flow at the opening is This seems to be due to the fact that there is no component parallel to the axis, that is, any minute flow mass of the driving flow flows toward the axis of the piping, making it difficult for pressure gradients to occur in the radial direction.

[Example] The present invention will be explained with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view of an embodiment of a jet pump according to the present invention, in which a male thread la is carved on the outer peripheral surface of the central rear part of an inner cylinder 1 having a uniform inner diameter, and a front end 1b of the outer surface of the inner cylinder 1 is formed. has a conical shape that shares an axis with the inner cylinder 1, and its diameter decreases toward the front end.

The rear part of the outer cylinder 2, which is arranged to fit the inner cylinder 1, is provided with a female thread 2a that engages with the male thread 1a of the inner cylinder. A bearing nut 3 is screwed into the outer cylinder 2 to prevent loosening of the screw connection between the outer cylinder 2 and the outer cylinder 2. The front part of the outer cylinder 2 is formed to have substantially the same inner diameter as the inner cylinder 1, and the front end 2b of the inner surface of the intermediate part of the outer cylinder 2 has a conical shape that shares an axis with the outer cylinder 2 and extends toward the front end. Although the diameter reduction angle of the outer surface front end 1b of the inner cylinder 6 and the diameter reduction angle of the intermediate inner surface front end 2b of the outer cylinder are not necessarily formed to be the same, in this example, are identically formed and therefore the outer surface of the inner cylinder l! The cross-sectional area of the flow path formed by 1ii1b and the front end 2b of the inner surface of the intermediate portion of the outer cylinder decreases toward the front. An annular region 4 is formed between the inner surface of the intermediate part of the outer cylinder 2 and the outer surface of the inner cylinder 1, and a driving flow pipe 5 is attached so as to communicate with the rear part of the annular region 4. The example is configured as described above, and when the distance between the front end 1b of the outer surface of the inner cylinder and the front end 2b of the inner surface of the intermediate part of the outer cylinder is adjusted by the bearing nut 3, and high pressure fluid is caused to flow from the drive flow pipe 5, The high-pressure fluid flows in from between the front end 1b of the outer surface of the inner cylinder and the front end 2b of the inner surface of the intermediate part of the outer cylinder, and becomes a driving flow.
The driven fluid in the inner cylinder 1 is driven. However, in this jet pump, all pipe diameters in the portion through which the driven fluid flows are formed to have substantially the same diameter, so even when the driven fluid contains solids, there is no risk of blockage due to solids. No, and the experimental results of this example showed that no cavitation occurred at all.

Next, the outer front end 1b of the inner cylinder and the inner front end 2b of the intermediate part of the outer cylinder.
The apex angle of the cone is the same as that of 20°,
Table 1 shows an example of the experimental results when the angle was changed to 30° and 40°. In this experiment, the inner diameter of the inner cylinder in Table 1 was formed to be the same diameter as the piping with a nominal diameter of 50A, and the piping with a nominal diameter of 50A was installed at the rear end of the inner cylinder of this jet pump.
A pipe with a nominal diameter of 100A was connected to the front end of the outer cylinder. As is clear from Table 1, when the apex angle is about 30°, the flow rate of the driven fluid and the pump efficiency are the highest, and it was found that it is preferable to set the apex angle to at least 20 to 40°.

[Effects of the Invention] In the present invention, since the pipes are formed to have substantially the same inner diameter, there is no risk of blockage due to solids even when conveying a fluid containing solids, and the driving flow is Since there is no component parallel to the pipe axis, there is no need to provide an air introduction pipe, and therefore a jet pump that does not cause a drop in the pumping amount of the driven flow has been obtained6.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of one embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a conventional example. 1...Inner tube 1a...Male thread 1b...Outer surface front end 2...Outer tube 2a...Female thread 2b...Intermediate inner surface front end 3...Bearing nut 4...Annular region 5 ... Drive flow piping

Claims (4)

[Claims] (1) Pipes having substantially the same inner diameter are provided, and first and second conical shapes that share an axis with the piping have an annular tapered opening whose inner and outer walls are the positions where the piping intersects with the piping, respectively. A jet pump provided in the piping and having a driving flow piping attached to the opening. (2) A thread is carved on the outer circumferential surface of an inner cylinder having substantially the same inner diameter, and the front end of the outer surface of the inner cylinder is reduced in diameter into a first conical shape that shares an axis with the inner cylinder; A female thread that engages with the male thread is carved in the rear part of the outer cylinder into which the inner cylinder is inserted, a front part of the outer cylinder is formed to have substantially the same inner diameter as the inner cylinder, and a middle part of the outer cylinder is formed. an annular region between the inner surface of the intermediate portion of the outer cylinder and the outer surface of the inner cylinder; A jet pump having an annular region having a rear portion thereof communicating with a driving flow piping. (3) The jet pump according to claim 1 or 2, wherein the first and second conical shapes have substantially the same apex angle. (4) The jet pump according to claim 3, wherein the substantially same apex angle is 20 to 40 degrees.