RU2516472C2 - Borehole motor - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to electrical engineering and machine building, particularly, to borehole motors to lift bed fluid. Proposed borehole motor comprises stator with toothed magnetic core accommodating the rotor. Stator teeth internal surface has grooves regularly arranged in circle in axial direction, the number making three, or being multiple of three.

EFFECT: lower reactionary torque, hence, vibration, better starting properties.

2 cl, 8 dwg, 2 tbl

Description

The invention relates to the field of electrical engineering and mechanical engineering, in particular to submersible motors for lifting formation fluid.

Known submersible electric motor containing a stator with a toothed magnetic circuit, on the inner surface of which grooves are made in the axial direction, and a rotor placed inside it (USSR author's certificate No. 255397, Н02К 5/12, publ. March 31, 1970).

The disadvantage of this design is the increased reactive moment due to the presence in the engine bore of two diametrically spaced grooves that serve to fix the bearings.

The closest in technical essence to the claimed one is a submersible electric motor containing a stator with a toothed magnetic circuit, on the inner surface of which one or two grooves are made in the axial direction, and a rotor placed inside it (patent RU 2192700 C1, H02K 5/16, F04D 13/08 , published on November 10, 2002).

The known engine has an increased reactive moment, due to the fact that during the rotation of the magnetic field, due to the uneven magnetic conductivity of the gap, pulsations of the magnetic flux occur. The reactive moment leads to an increase in the amplitude of vibration and impairs the reliability of the start-up.

In submersible motors with permanent magnet excitation, the influence of the reactive moment is more pronounced than in asynchronous electric motors. To reduce the reactive moment in asynchronous electric motors, the angular displacement of the rotor packages by half of the tooth division of the stator is used, and in electric motors with excitation from permanent magnets, the angular displacement of the magnets in the package is also used. However, the reactive moment of these technical solutions is not properly eliminated.

The objective of the present invention is to reduce vibration and improve the starting properties of submersible engines by reducing reactive torque.

The specified technical result is achieved due to the fact that in the submersible electric motor containing a stator with a toothed magnetic circuit, on the inner surface of which grooves are made in the axial direction, and a rotor located inside it, three or a multiple of three number of grooves evenly spaced along the stator are made the circumference of the inner surface of the stator.

In addition, in the particular case of implementation, in the submersible motor with excitation from permanent magnets, the rotor is made with the offset of the magnets of the package.

The invention is illustrated by drawings, where figure 1 shows a section of the proposed submersible electric motor with three grooves; figure 2 is a section of a submersible motor with 12 grooves; figure 3 - package of the rotor with permanent magnets; figure 4 - package of the rotor made with the offset of the magnets of the package; figure 5 is a graph of the specific (per unit length of the active part of the electric motor) reactive moment from the angular position of the rotor with the number of grooves 1, 2 and 3 on the inner surface of the stator; figure 6 is a graph of the specific reactive moment on the angular position of the rotor with the number of grooves 2, 6 and 12 on the inner surface of the stator; Fig.7 is a graph of the specific reactive moment on the angular position of the rotor with the number of grooves 1, 2 and 3 on the inner surface of the stator for the motor, the rotor of which is made with the displacement of the magnets of the package; on Fig is a graph of the specific reactive moment on the angular position of the rotor with the number of grooves 2, 6 and 12 on the inner surface of the stator for the motor, the rotor magnet packages of which are made with an offset.

Submersible electric motor contains a stator 2 and a rotor 3. On the inner surface of the stator 2 there are grooves 1, evenly spaced on its circumference (figure 1, 2). The grooves 1, made in the axial direction, are designed to protect the outer ring of the bearing from rotation and are used when assembling the stator package. The number of grooves is equal to or a multiple of three. Depending on the number of grooves, the maximum value of the reactive moment changes.

The designs of plain bearings used in submersible induction motors and permanent magnet excitation motors are similar.

In engines with excitation from permanent magnets (figure 3), half of the magnets 4 of the package is shifted by half the tooth division of the stator (figure 4).

The proposed technical solution allows for a minimal change in design to sharply reduce the reactive moment.

Table 1 Number of grooves Useful moment, Nm / m Reactive moment without pole shift, Nm / m Reactive moment with pole shift, Nm / m one 156.4 1.53 1.11 2 156.2 3.02 1.93 3 156.1 0.96 0.32 6 155.6 1.02 0.45 12 154.7 1.17 0.90

Table 1 shows the estimated typical ratio of useful and reactive moments at equal currents in the armature winding for a different number of grooves on the inner surface of the stator (Figs. 1, 2) for various rotor designs (Figs. 3 and 4). From table 1 and the graphs in figure 5, 6, 7, 8 it follows that in an engine with the number of grooves up to 3N, where N = 1, 2, 3 ..., on the inner surface of the stator, the magnitude of the reactive moment decreases. But with an increase in the number of grooves, the value of the useful moment decreases, which is explained by an increase in the equivalent magnetic gap. Optimal, in terms of the ratio of reactive and useful moments, the result is achieved with three grooves on the inner surface of the stator.

Table 2 shows the estimated typical ratios in percent of useful and reactive moments at equal currents in the armature winding for a different number of grooves on the inner surface of the stator, for an electric motor with 7 pairs of poles on the rotor, made without biasing the magnets of the package. As a starting point for comparison, a design with two diametrically located grooves on the inner surface of the stator and 7 pairs of poles on the rotor was chosen. As in the previous case, the optimal result is achieved with three grooves on the inner surface of the stator.

table 2 Number of grooves Useful moment in% of the prototype moment Reactive moment in% of useful moment one 100.8 8.02 2 100.0 11/15 3 99.2 2.80 6 97.6 4.49 12 92.6 0.70

Thus, the proposed design provides a reduction in reactive moment, which helps to reduce vibration and improve the starting properties of submersible engines.

Claims (2)

1. Submersible electric motor containing a stator with a toothed magnetic circuit, on the inner surface of which grooves are made in the axial direction, and a rotor located inside it, characterized in that on the inner surface of the stator there are three or three times three number of grooves evenly spaced around the circumference. 2. Submersible motor according to claim 1, characterized in that the rotor is made with packages of permanent magnets located with an offset around the circumference.

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