JPH11294396A - Electric pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a nonconformity, since a drain plug is likely installed near the angle part where the chamfering of the casing inner wall of a pump is given, and in this case, a cross section part is formed near a drain hole to be a water passage, and thereby, a cavitation is generated, so as to generate an abnormal sound. SOLUTION: Of the casing inner wall angle part 5a where a chamfering is given to the inner wall of a casing 5 around the full periphery, only a partial scope near a drain plug is made into an edge, it is changed from R to an edge smoothly, a drain plug hole is provided to the part of the edge part 5c, the structure of the drain plug hole is made in the form to form no cross section, and the generation of a cavitation resulting from the cross section at the drain plug hole is suppressed, so as to prevent the generation of an abnormal sound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric pump provided with a pump casing in which a drain plug is arranged near a chamfered corner of an inner wall.

[0002]

2. Description of the Related Art In recent years, small-sized electric pumps have been built in hot water supply / heating machines and the like for additional cooking and circulation of baths or for circulation of antifreeze and the like for central heating.

[0003] In these electric pumps, if the circulating water in the pump room freezes in winter, the pump casing may be damaged due to the freezing and expansion of the circulating water in the pump room. Therefore, when there is a possibility that the circulating water freezes, a caution is given to discharge the circulating water in the pump chamber. For this reason, the electric pump is provided with a drain plug for discharging circulating water in a part of the pump casing in order to discharge circulating water in the pump chamber.

Conventionally, this type of electric pump has a configuration as shown in a sectional view of a conventional electric pump shown in FIG.
Hereinafter, the configuration will be described with reference to the drawings.

[0005] In FIG. 3, reference numeral 1 denotes an electric motor, and a rotating shaft 2 protrudes from one side of the motor. An impeller 3 is attached to a tip end of the rotating shaft 2. The impeller 3 is housed in a pump chamber 6 formed by a casing 5 and a separation plate 4.

The casing 5 is provided with a drain plug 8 for discharging circulating water filled in the pump chamber 6. The drain plug 8 is connected to the outside of the equipment body 11 such as a hot water supply / heating unit by a dedicated connection pipe 10. When drainage of the circulating water is necessary, for example, when there is a possibility that the circulating water is frozen, the connection is performed. The circulating water can be discharged to the outside via the pipe 10.

[0007] In addition to the internal pressure caused by the operation of the pump, the pump chamber 6 may be subjected to a pushing pressure, a primary water supply pressure, or the like. Therefore, the pump housing needs to have sufficient strength. For this reason, the casing inner wall corner 5a is chamfered at least R2 or more.

The bracket 7 holds the separation plate 4 and connects the motor unit and the pump unit. Further, the motor unit and the pump unit are sealed by the shaft sealing device 9. A commonly used shaft sealing device is a mechanical seal, which is inexpensive, but is liable to leak water over a long period of operation, so that a magnet coupling system using a magnetic coupling force of a magnet is becoming widespread. is there.

Next, the operation of the electric pump configured as described above will be described. When the electric motor 1 is operated, the impeller 3 attached to the tip of the rotating shaft 2 rotates. As a result, a pressure difference is generated between the suction side A and the discharge side B of the pump chamber 6, and the circulating water is sucked from the suction side joint 5A and discharged toward the outer periphery of the blade with the rotation of the impeller 3.

Further, the discharged circulating water is supplied to the casing 5
Is guided along the rotation direction of the impeller 3, and is discharged from a discharge hole of a discharge side joint 5B provided on a part of the inner wall of the casing 5.

FIG. 4 is a view taken in the direction of arrows FF in FIG.
As shown in this figure, the circulating water sucked from the suction side joint 5A is discharged toward the outer periphery of the impeller 3, reaches the inner wall of the casing, moves along the direction of the arrow, and is discharged from the discharge side joint 5B. Is done. At this time, the circulating water is guided toward the joint B via the drain plug hole 8a.

[0012]

In the electric pump having the above construction, the position of the drain plug 8 in the casing 5 of the pump section is shown in a sectional view of the pump section when the drain plug does not cover the corner of the inner wall of the casing in FIG. There is no problem if it is located in the plane portion 5b of the casing 5 as described above, but due to the attachment to the equipment, the drain plug hole 8a is inevitably formed in the inner wall corner 5 of the casing 5 on which the R is provided.
In some cases, it is necessary to dispose it at a location such as a.

FIG. 5 is a perspective view showing the vicinity of a drain plug of a casing of a conventional electric pump. When the drain plug hole 8a is arranged at a location where it covers the casing inner wall corner 5a of the casing 5, the casing inner wall corner 5a of the casing 5 is rounded. A cross section 8b occurs.

As described above, when the circulating water sucked from the suction side joint 5A flows in the direction of the arrow, a part of the circulating water collides with the cross section 8b formed near the drain plug hole 8a.
There is no particular problem if the temperature of the circulating water is normal temperature or about 50 to 60 ° C. However, when the equipment is used for heating or the like, the water temperature becomes 80 ° C. or more, and the circulating water passage has a cross section 8b. Cavitation occurs when there is such an edge part,
May cause abnormal sound.

Further, from the viewpoint of the mold structure for molding the casing 5 made of resin, the mold pin for molding the drain plug hole 8a of the casing 5 needs to be set up from the cavity side, and the core side mold is touched. Structure. If the drain cock hole 8a is at the position shown in FIG. 8 described above, as shown in the sectional view of the casing molding die of FIG.
Drainage tap hole 8 simply raised from cavity side mold 13
Only by touching the drainage plug mold pin 12 of a with the core mold 14, there is no problem in terms of mold structure and mold strength. However, when the drain plug 8 hangs on the corner 5a of the inner wall of the casing 5 on which the inner wall of the casing 5 is rounded, the drain plug hole 8a is formed as shown in the sectional view of the conventional touch mold for forming a casing shown in FIG. The drain plug pin 12 and the core-side die 14 of R are touched by R, and the drain plug die pin 12
Since the sharp edge 12a of the thin portion is formed at the same time, the strength of the mold becomes insufficient, and it is difficult to adjust the radius to cause burrs, so that the touch structure is very difficult.

For this reason, as shown in the sectional view of the conventional in-lock structure mold for casing molding shown in FIG. 7A, the drain plug pin 12 of the drain plug hole 8a is inserted into the core side mold 14. It becomes a structure to be locked. However, also in this structure, a sharp edge 14a of a thin portion is formed in a part of the core-side mold 14, as shown in a view taken along a line GG in FIG. 7A shown in FIG. There is concern about early breakage due to insufficient mold strength.

The present invention has been made in consideration of the above-mentioned conventional problems, and an electric pump which does not generate cavitation due to a drainage plug hole in a pump casing and has a simple structure for a mold for molding the pump casing. The purpose is to provide.

[0018]

In order to achieve this object, an electric pump according to the present invention is provided at the corner of the inner wall of a casing forming a pump chamber over the entire circumference for the purpose of increasing the strength of the casing. Of the R, only a part of the R near the drain plug is eliminated, and a cross section is not formed in this part.

According to the present invention, since no cross-section is formed at the corner of the inner wall of the pump casing, cavitation does not occur even when the circulating water is at a high temperature, and abnormal noise can be suppressed. Further, a mold for forming the pump casing can be realized with a simple touch structure of the pin and the core, and there is no problem in terms of the strength of the mold.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention comprises an electric motor, an impeller fixed to a rotating shaft of the electric motor, and a casing for forming a pump chamber for accommodating the impeller. Comprising a drain plug disposed near the corner where the chamfer of the inner wall of the casing is provided,
An electric pump having a casing shape in which a cross section is not formed in a direction perpendicular to a flow of circulating water along a corner of the inner wall in a hole portion of the drain plug serving as a water passage. Since there is no cross section perpendicular to the flow of circulating water near the hole, cavitation does not occur even if the circulating water is at high temperature, abnormal noise can be eliminated, pump efficiency can be improved, and the mold structure Has the effect of simplifying the process and having no problem in strength.

Hereinafter, embodiments of the electric pump according to the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is an enlarged perspective view of the vicinity of a drain plug of a pump casing in an electric pump according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view of a molding die of the pump casing. Note that the basic operation of the electric pump is not different from that of the related art, and the description thereof is omitted. In addition, the same reference numerals are given to the same components as those in the above-described conventional example in each drawing.

The feature of the electric pump according to the first embodiment lies in the shape of the casing of the pump section, that is, as shown in FIG. 1, the electric pump is provided on the entire periphery of the casing inner wall corner 5a of the casing 5. Of R, the edge portion 5c is formed only in the vicinity of the drain plug hole 8a, and smoothly changes from the casing inner wall corner portion 5a to the edge portion 5c. Then, a drain plug hole 8a is provided in the edge portion 5c.

Due to this shape, the cross section 8b as shown in FIG. 5 is not formed near the drain plug hole 8a. Further, of the chamfered casing inner wall corner 5a of the casing 5, the edge 5c near the drain plug hole 8a is in a small range, so that the mechanical strength of the casing 5 is not different from that of the conventional casing.

Further, as for the mold for molding the resin casing 5, as shown in FIG. 2, the drain plug pin 12 of the drain plug 8 set on the cavity mold 13 is simply a core side mold. All you have to do is touch the mold 14,
Since neither the drain plug pin 12 nor the core-side die 14 has a thin portion, a structure having no problem in strength can be realized.

[0025]

As is apparent from the above description, the electric pump of the present invention has a cross section formed in the drain plug hole located near the corner of the inner wall, which is a water passage for circulating water, in the casing of the pump. As a result, even when the temperature of the circulating water is high, there is no cavitation caused by the drain plug and the effect of suppressing the occurrence of abnormal noise can be obtained.

Also, a mold for molding the pump casing can be realized with a simple touch structure of a pin and a core, and there can be no problem in strength of the mold.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of the vicinity of a drain plug of a pump casing in an electric pump according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a molding die for the pump casing.

FIG. 3 is a cross-sectional view of a conventional electric pump.

FIG. 4 is a view taken in the direction of arrows FF in FIG. 3;

FIG. 5 is a perspective view of the vicinity of a drain plug of a casing of a conventional electric pump.

FIG. 6 is a sectional view of a conventional touch structure mold for casing molding.

7A is a cross-sectional view of a conventional mold for forming an in-lock structure for casing molding, and FIG. 7B is a view taken along a line GG in FIG. 7A (core-side mold).

FIG. 8 is a cross-sectional view of the pump section when the drain plug does not cover the corner of the inner wall of the casing.

FIG. 9 is a sectional view of the casing molding die of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric motor 2 Rotating shaft 3 Impeller 4 Separation plate 5 Casing 5A Suction side joint 5B Discharge side joint 5a Casing inner wall corner 5b Flat part 5c Edge part 6 Pump room 7 Bracket 8 Drain plug 8a Drain tap hole 8b Cross section 9 Shaft sealing Apparatus 10 Connecting pipe 11 Equipment main body 12 Drain tap mold pin 12a Sharp edge 13 Cavity side mold 14 Core side mold 14a Sharp edge

Claims (1)

[Claims] An electric motor, an impeller fixed to a rotating shaft of the electric motor, and a casing for forming a pump chamber for accommodating the impeller, wherein a corner portion of an inner wall of the casing is chamfered. It is a configuration in which a drain cock is disposed in the vicinity, and in a hole portion of the drain cock that becomes a water passage, a casing shape that does not form a cross section in a direction perpendicular to the flow of circulating water along the inner wall corner portion. An electric pump, characterized in that: