CN100438308C - Single-phase motor for submersible pump - Google Patents

Abstract

A single-phase motor (10) for a submersible pump comprises a box-shaped main body (11), a stator winding group (12), a rotor (13), and a pump connection head (15) housed in the main body (11). The motor is characterized in that an annular capacitor (14) is also housed in the main body (11), and the annular capacitor is placed between the pump connection head (15) and the stator winding group (12). With this motor, a control panel and corresponding connecting wires can be omitted, and electrical wiring can be prevented from passing through the stator winding, thereby simplifying the motor structure.

Description

Single phase motors for submersible pumps

technical field of invention

The invention relates to a single-phase motor for a submersible pump.

Background technique

The commonly used motor is a single-phase asynchronous motor that requires two stator windings with a 90° phase difference to start.

One method used to phase shift the two windings is to insert a permanently connected capacitor at the power supply of one of the windings.

This type of motor consists of a generally cylindrical body containing a stator winding set which drives a rotor whose head protrudes at the pump coupling.

This motor and pump combination is used in wells that can be as deep as several hundred meters.

If the capacitor is integrated in the control panel of the motor, it is necessary to run the wires from the capacitor to the motor, thus using a cable with three leads plus a ground wire.

One possible solution to this problem is that the motor is equipped with an internal capacitor which has a connection inside said motor and is brought out of the motor with a 2-conductor cable with a ground wire.

This solution allows the motor to be connected directly to the mains supply.

In some existing solutions, the cylindrical container of the electric motor is provided in the lower part, ie the part opposite the coupling head of the pump, with a compartment for accommodating a capacitor.

Although integrating the capacitors within the motor body can eliminate the need for a control panel, this solution has drawbacks.

As mentioned, the capacitors are actually placed in the lower part of the motor, at the end opposite the stator windings and the electrical connections usually from the pump coupling.

The supply cables for the capacitors must therefore be properly insulated and run through the entire motor adjacent to the stator winding sets, adding to the geometrical complexity of the motor; Suitable windings for capacitive connections, but even if automatic production of such assemblies was possible, it would complicate it.

Contents of the invention

It is an object of the present invention to solve or significantly alleviate the problems associated with conventional single-phase motors for submersible pumps.

An important object is to provide a motor which can be directly connected to the line without interposing a board containing the capacitor and which reduces the number of wires.

Another object of the invention is to eliminate electrical wiring passing through the stator windings, also without providing special windings.

This object, and these and other objects which will become clearer hereinafter, are achieved by a single-phase motor for a submersible pump comprising a box-shaped body and a A stator winding group, a rotor and a pump coupling head, wherein: a ring capacitor is also accommodated in the main body, and the ring capacitor is placed between the pump connection head and the stator winding group.

With this motor, the control panel and corresponding connecting wires can be omitted, and the electrical wiring can be avoided from passing through the stator winding, thereby simplifying the structure of the motor, reducing the volume of the main body of the motor, and ensuring effective sealing of electrical parts.

Brief description of the drawings

Other features and advantages of the invention will become clearer from the description of a preferred but not exclusive embodiment of the invention. This embodiment is illustrated in the drawings by way of non-limiting example only. In these drawings:

Fig. 1 is a longitudinal sectional view of an electric motor according to the present invention;

Fig. 2 is a perspective view of a capacitor used in the motor shown in Fig. 1;

FIG. 3 is a cross-sectional view of the capacitor shown in FIG. 2 .

Detailed ways

Referring to the drawings, an electric motor for a submersible pump according to the present invention is generally identified by the reference numeral 10 .

The motor 10 is a single-phase asynchronous motor housed in a generally cylindrical box-shaped body 11 .

A set of stator windings 12 is housed in the body 11 and a rotor 13 is included in these stator windings.

The stator winding set 12 consists of two separate stator windings. One of the two stator windings is connected to a power supply, the other is connected to a capacitor, generally identified by the reference numeral 14 .

The capacitor 14 is a ring capacitor placed between the stator winding set 12 and the pump connection 15 .

In fact, the coupling head 15 is provided with a screw 16 for fastening the pump, not shown in the figures but of any known type. And the head 17 of the rotor 13 protrudes from the coupling head 15 .

The head 17 is coupled to the pump shaft.

Capacitor 14 is advantageously a thin-film capacitor formed by a longitudinally elongated plate 18 surrounding a tubular support 19 and housed in a tubular box 20 . The box 20 is filled with resin at the ends for insertion of the board 18 .

The box 20 is provided with inner and outer longitudinal grooves 21 at the tubular inner wall 22 .

In particular, the inner longitudinal slot 21 a is used for the passage of the connecting wires 23 of the plate 18 , while the outer longitudinal slot 21 b is for the passage of the power supply wires of the stator winding group 12 .

Finally, the tubular box 20 is filled with resin 24 to insulate the plate 18 .

In practice it has been found that the intended aim and objects have been achieved by the present invention.

In particular, it is evident that the specific shape of the capacitor allows said capacitor to be placed in a favorable position.

The disclosures in Italian Patent Application No. PD2000A000085 from which this application claims priority are incorporated herein by reference.

Claims (4)

1. A single-phase motor (10) for a submersible pump, comprising a box-shaped main body (11) and a stator winding group (12), a rotor (13) and a rotor (13) contained in the main body (11) A pump coupling (15), characterized in that: an annular capacitor (14) is also accommodated in the main body (11), and the annular capacitor is placed between the pump coupling (15) and the stator winding group ( 12) Between. 2. An electric motor as claimed in claim 1, characterized in that said capacitor consists of a longitudinally extending film capacitor which surrounds a tubular support (19) and is housed in a resin-filled tubular box (20). 3. The electric motor according to claim 2, characterized in that said tubular box (20) is provided with an external longitudinal groove (21b) at the tubular inner wall (22). 4. The electric motor according to claim 2, characterized in that said tubular box (20) is provided with internal longitudinal grooves (21a) at the tubular inner wall (22).

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