JPH09209974A - Submersible motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve product reliability by fixing an FG magnet to an FG yoke having only a little gap to a motor circuit board provided on an outer side surface of an upper end bracket, and pushing an upper shaft bearing to a bearing support part by an insert provided on the upper end bracket. SOLUTION: A motor circuit board 14 is fixed to an upper end bracket 11 by a screw 16. An FG coil inverter is set to face an FG magnet 7 having a micro-gap between them in such a way that a magnetic field of the FG magnet is applied. When a rotor part rotates, the magnetic field of the FG magnet 7 is rotated, so an excited voltage in an FG coil pattern in accordance with rotation speed is outputted as a rotation signal. The lower side of a bearing 10a supporting the upper side of a motor rotation shaft 4 is supported by an insert 49 as a presser plate fixed on the upper end bracket 11 by a bolt 48. In this constitution, precession rotation can be prevented.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an underwater motor,
For example, the present invention relates to improvement of a submersible motor used by incorporating it into a vertical submersible pump used for treating wastewater.

[0002]

2. Description of the Related Art A commonly used sewage treatment system is
It consists of a water storage tank, aeration tank, settling tank, and disinfection tank, and the submersible pump is located at the first stage of sewage treatment.

The submersible pump uses three float switches (for high water level detection, medium water level detection and low water level detection) installed externally. The operation method is as follows: dirty water flows into the water tank and the water level rises. Then, the low water level detection float switch is turned on, the water level further rises, and the pump motor is started when the medium water level detection float switch is turned on. At that time, the pump motor is controlled at a constant rotation speed.

Then, when the water level is lowered and the medium water level detection float switch is turned off, speed-up rotation control is performed.

Although the water level is further lowered and the head height is increased by the speed-increasing rotation control, this problem is solved by supplying a certain amount of waste water to the next aeration tank by increasing the rotation speed of the pump. You can

The motor is stopped at the time when the water level is lowered and the medium water level detection float switch is turned off, and the water level is further lowered and the low water level detection float switch is turned off.

Further, the high water level detecting float switch lowers the motor rotation speed to suppress the drainage amount when the inflow amount of the dirty water is large despite the rotation of the motor.

As a conventional vertical submersible pump, an induction motor using a single-phase or three-phase AC power source is generally used, as shown, for example, in Japanese Utility Model Publication No. 5-14591.

However, in the case of an induction motor, it is unavoidable that the motor rotation speed changes due to the difference in the power supply frequency of the AC power supply.

It is possible to arbitrarily set the number of revolutions independent of the frequency of the AC power source, improve the starting torque, change the number of revolutions, etc. by adding a control circuit such as an inverter control to the conventional induction motor. According to this, in addition to the induction motor of the conventional submersible pump, in order to newly add a control unit,
The submersible pump will be upsized, and in the case of an induction motor, large torque cannot be generated at startup.

Further, in the case of an AC power source, the number of revolutions is determined by the frequency, and therefore in order to obtain the same performance in the same model, it is necessary to have a pump runner and a pump casing for each frequency.

On the other hand, as a brushless motor type submersible pump, a deep well submersible pump has been conventionally proposed.
In the case of a brushless motor using a DC power supply, the AC power supply cannot be used directly, and when operating with the AC power supply, a new power supply switching device is required, which is a problem in terms of usability.

On the other hand, the present inventors set the motor to DC.
A brushless motor, a rotation speed detection unit for controlling the rotation speed, a control unit for arbitrarily setting the rotation speed, and an AC
A submersible pump that has a DC power conversion circuit built in rather than a power source was proposed first, and according to this, unlike the conventionally proposed deep well submersible pump, which requires a new power switching device. In addition, the brushless motor is more efficient than the induction motor, and generates a large torque at the time of start-up, which is advantageous in the use of a highly viscous liquid.

[0014]

However, conventionally,
The bearing, which is press-fitted to the upper side of the motor rotating shaft to support it, rotates little by little under the influence of the rotation of the motor rotating shaft. Friction is generated in the bearing and outer ring creep is generated in the bearing, and a gap is created between the bearing and the end bracket.

Although the motor rotating shaft is preloaded in the upward direction by the leaf spring below the bearing supporting the lower side of the motor rotating shaft, the bearing and the end supporting the upper side of the motor rotating shaft are supported. If a gap is created between the bracket and the rotation of the motor rotation shaft,
This movement leads to a variation in the distance between the FG yoke attached to the motor rotation shaft and the motor rotation board attached to the end bracket, resulting in pulse omission in the control of the motor rotation detection system. It causes trouble.

It is an object of the present invention to provide an improved submersible pump capable of improving product reliability as compared with the conventional one.

[0017]

[Means for Solving the Problems] The object is to provide a stator,
A rotor arranged inside the stator, a cylindrical motor housing that fits on the outer circumference of the stator and surrounds the outer circumference, and an upper end bracket and a lower end that are provided at both ends of the motor housing, respectively. Bracket and
An upper side bearing an upper side bearing for supporting the rotation shaft of the rotor, and an inner side surface of the upper side end bracket having a tightening bolt for tightening the upper side and the lower side end brackets so as to hold the motor housing from both ends. In a submersible motor having a bearing support portion and a lower bearing support portion on which the lower bearing supporting the rotation shaft of the rotor is fitted on the inner surface of the lower end bracket, the outer surface of the upper end bracket. A motor circuit board is attached to the motor circuit board, and the FG magnet is fixed to the FG yoke fixed to the rotary shaft so as to face the motor circuit board with a slight gap G therebetween.
This is accomplished by providing the upper end bracket with an insert (presser plate) that presses the upper bearing against the upper bearing support.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

First, the structure of the brushless motor will be described with reference to FIGS. 1, 2, and 5.

The stator portion of the brushless motor has a stator winding 2 in a slot formed in the inner circumference of the stator core 1.
Is directly wound by a winding machine via an electrical insulator, and is further press-fitted and fastened to the motor housing 3.

In the rotor portion of the brushless motor, the rotor yoke 5 is press-fitted and fastened to the motor rotating shaft 4, and the main magnet 6 for producing a magnetic field as a motor is fixed to the rotor yoke 5 with an adhesive or the like, and FG The FG magnet 7 that forms a magnetic field as a sensor is fixed to the FG yoke 8 with an adhesive or the like, and the FG yoke 8 is fixed to the motor rotation shaft 4 by the lock nut 9, thereby the bearing 1
The upper end bracket 11 and the lower end bracket 12 are rotatably supported by 0a and 10b.

The motor housing 3 is preferably made of a stainless steel plate in consideration of mechanical strength, corrosion resistance, heat dissipation of the stator winding 2, and the like.

Next, the rotation speed detecting means by the hall element 13 (see FIG. 6) for switching the phase of the power supply to the stator winding 2 and the FG sensor for detecting the rotation speed for controlling the rotation speed. Will be described.

In FIG. 6, an FG coil pattern 14a and a lead pattern 14b soldered to the Hall elements 13a to 13c are provided on a motor circuit board 14 made of a composite material such as copper foil and paper phenol. And the motor cable 15 is connected to them.

The motor circuit board 14 is fixed to the upper end bracket 11 with screws 16. FG coil pattern 1 in a state where the stator part and the rotor part are combined
As shown in FIG. 5, the magnetic field of the FG magnet 7 in the rotor portion 4a faces the FG magnet 7 through a minute gap so that the magnetic field of the FG magnet 7 rotates when the rotor portion rotates. By doing so, the voltage induced in the FG coil pattern 14a according to the rotation speed is output as a rotation signal.

The Hall elements 13a to 13c face the FG magnet 7 with a minute gap therebetween so that the magnetic field of the FG magnet 7 in the rotor portion acts on the Hall elements 13a to 13c.
Rotational torque is generated by controlling the switching of the feeding phase of the stator winding 2 based on the magnetic pole position detection signals of the Hall elements 13a to 13c.

Next, referring to FIG. 1 and FIG. 4, a circuit configuration for generating a DC power source from an AC power source, switching the feeding phase of a drive current flowing through the stator winding 2 of the brushless motor, and controlling the rotation speed will be described. explain.

This circuit configuration basically has a motor control circuit 17 for controlling the power feeding phase switching control of the stator winding 2, rotation speed control, overload protection and the like, and an AC power source converted to a DC power source. And a DC power conversion circuit 18 for

A motor control circuit board 20 having a power supply phase switching control transistor (motor driver) 19 is attached to an aluminum heat dissipation plate 21 for heat dissipation. Details of the upper end bracket 11 are shown in FIGS.
This will be described with reference to FIG.

The upper end bracket 11 is provided with a centering protrusion 11a for aligning with the motor housing 3 and a tightening bolt (see FIG. 2) in order to fix the brushless motor in a fixed position and install it vertically. A plurality of motor fixing screw holes 11b for fixing the motor housing 3 are provided by the reference numeral 44).

As will be described later, the end bracket 11 has a rubber ring for keeping watertightness (reference numeral 23 in FIG. 1) for ensuring watertightness of the joint surface when the circuit protection cover 22 is butted and screwed and fixed. The rubber ring mounting groove 11c (see the reference) is provided.

Next, the circuit protection cover 22 will be described with reference to FIGS.
This will be described with reference to FIG.

The circuit protection cover 22 is placed on the upper end bracket 11, and is screwed and coupled with the case coupling bolt 24 and the case coupling nut 25, so that the upper end bracket 11 is secured by the watertight retaining rubber ring 23.
And are joined in a watertight state.

The circuit protection cover 22 includes a handle 22a for transporting and installing the submersible pump, a support screw 22b for mounting the float switch support 26 shown in FIGS. 1 and 3, and a DC power conversion circuit 18. External AC
A cable through hole 22c for penetrating the circuit protection cover 22 and pulling it out to the outside with a power supply cable (see reference numeral 27 in FIG. 1 and FIG. 2) for receiving the power supply kept watertight, and a motor control circuit 17 And a cable through hole 22d for penetrating the circuit protection cover 22 and pulling it out to the outside in a state where the water level detection float switch cable (see reference numeral 28 in FIGS. 2 and 3) is kept watertight.

The detailed structure of the cable outlet portion will be described with reference to FIG.

The power supply cable 27 and the float switch cable 28, which are made of rubber and are integrally molded with the bridging lead-out rings 29 and 30, respectively.
Of the flanges 31a, 31b while being inserted into the cable through holes 22c, 22d of the flanges 31a, 31b.
Metal sealing caps 32a, 32b abutting the outside of the
Lead protection screw holes 22e, 22 of the circuit protection cover 22
By tightening the screws 33a and 33b screwed to f, the flanges 31a and 31b are brought into close contact with each other by the elasticity of rubber to obtain watertightness.

In FIG. 1, the intermediate casing 34, with the mechanical seal 35 interposed, is used for the rotary shaft 9 of the motor.
Is fixed to the bottom of the lower end bracket 12 with a screw 36, and the connecting surface thereof is fixed to the O-ring 37.
To make it watertight.

The pump portion is a vortex type pump, and the pump runner 38 is fixed to the shaft end of the motor rotating shaft 4 penetrating the intermediate casing 34 by a screw 39.

The upper pump casing 40 and the lower pump casing 41 are connected to each other to form a pump runner 38.
To form a pump chamber for housing the.

The pump lower casing 41 has a suction hole 41.
a is formed, and the upper pump casing 31 is provided with a flange 42 having a male screw portion for pipe connection.

The circuit protection cover 22, the upper end bracket 11, the lower end bracket 12, the intermediate casing 34, the pump upper casing 40, and the pump lower casing 41 are made of synthetic resin material.

In the figure, reference numeral 11d indicates a packing mounting groove provided on the lower side of the upper end racket 11, and 12a indicates a packing mounting groove provided on the upper side of the lower end racket 12.

Here, the motor characteristics of the brushless motor and the induction motor are compared and shown in FIG.

The characteristic of the brushless motor is that the torque and the rotational speed change linearly when the rotational speed is not controlled (when the rotational speed is not controlled), and when the rotational speed is 0, that is, the torque at startup is It will be the maximum.

Unlike the induction motor, the brushless motor can set the maximum number of revolutions arbitrarily by changing the magnetic flux of the magnet and the coil winding specifications, and the desired number can be obtained without being influenced by the frequency of the AC power source. The number of rotations can be obtained.

Further, in the brushless motor, the starting performance can be improved by increasing the torque at the time of starting.

The submersible pump configured as described above is installed in water by connecting a water distribution pipe to the flange 42.

The DC power conversion circuit 18 includes the power cable 2
The AC power received through 7 is converted to DC power. The motor control circuit 17 uses this DC power source to turn on / off the power supply to the brushless motor by referring to the water level detection signals from the water level detection float switches (reference numerals 43a to 43c in FIG. 3) to operate the pump. And stop.

If the rotation speed control is executed using the rotation detection signal from the FG sensor, the rotation speed can be controlled to be constant with respect to the load torque in a certain range. This means that the amount of change in the pump discharge flow rate is reduced by keeping the rotation speed constant with respect to changes in the load such as the pump head.

If feedback control is performed so that the pump discharge flow rate is constant, a constant discharge quantity can be stably obtained regardless of the lifting process.

Further, by providing the motor control circuit 17 with a protection circuit such as a current limiter, it is possible to perform a safety protection operation such as stopping the motor at the time of overload.

Here, the characteristic features of this embodiment will be described below.

First of all, in this embodiment, the lower side of the bearing 10a that supports the upper side of the motor rotating shaft 4 is fixed to the upper end bracket 11 by a bolt 48, which is an insert (this insert). Can be made of an iron material, a synthetic resin material, or any other suitable material) 49.

That is, as described above, the motor rotating shaft 4
The bearing 10a press-fitted to the motor rotating shaft 4 for supporting the upper side of the bearing 10a rotates little by little under the influence of the rotation of the motor rotating shaft 4, and the bearing 10a and the upper end bracket 11 on the outer periphery of the bearing 10a are rotated by the aging. A friction is generated between the bearing 10a and the outer ring creep on the bearing 10a.
A gap is created between a and the upper end bracket 11.

As described above, the motor rotating shaft 4 receives the upward preload by the leaf spring 50 below the bearing 10b supporting the lower side of the motor rotating shaft 4, but When a gap is formed between the bearing 10a that supports the upper side of the rotating shaft 4 and the upper end bracket 11, the rotation of the motor rotating shaft 4 is microscopically viewed as a "pestle" shape, and the movement of the motor rotating shaft 4 is The FG yoke 8 attached to the shaft 4 and the upper end bracket 11
This leads to a variation in the distance between the motor rotation boards 14 attached to the motor rotation board 14 and causes a defect such as a missing pulse in the control of the motor rotation detection system.

On the other hand, according to the present embodiment, by supporting the lower side of the bearing 10a supporting the upper side of the motor rotating shaft 4 by the insert 50, the bearing 10a and the upper end of the outer periphery thereof are supported by the above-mentioned phenomenon. Bracket 1
Even when friction occurs between the bearing 10a and the outer ring creep in the bearing 10a, the rotation of the motor rotation shaft 4 does not cause the "pestle" -like rotation motion as described above, and the motor rotation detection system is controlled. It is possible to improve the reliability of the product by eliminating problems such as missing pulses.

Secondly, in the present embodiment, as shown in FIG. 2, the motor housing 3 located between the upper end bracket 11 and the lower end bracket 12 has a bulging portion (protruding portion) bulging outward. 3a is provided, and a tightening bolt 44 for connecting the motor housing 3 between the upper end bracket 11 and the lower end bracket 12 is provided inside the bulging portion 3a.
Is located outside the tightening bolts 44 composed of a plurality of parts, and seals the upper end bracket 11 and the motor housing 3 in a watertight manner. For example, a packing 45 made of a rubber material and the motor housing 3 and the lower side. A packing 46 that seals the space between the end brackets 11 in a watertight manner is arranged, and according to this configuration, between the upper end bracket 11 and the motor housing 3 around the entire circumference of each of the plurality of tightening bolts. Furthermore, it is not necessary to seal the motor housing 3 and the lower end bracket 11 one by one, so that the number of assembling steps of the submersible pump can be reduced and the product cost can be reduced. it can.

On the other hand, in the state of FIG. 2, in the case of a simple motor housing having no bulging portion 3a as described above, a space between the upper end bracket and the motor housing and a space between the motor housing and the lower end bracket are provided. Although the tightening bolts to be connected come out to the outside of the motor housing, according to this configuration, in addition to the packings 45 and 46 described above, a plurality of tightening bolts 1 are provided.
It is necessary to seal the entire circumference of each book between the upper end bracket and the motor housing and between the motor housing and the lower end bracket by packing.

Further, when the tightening bolt is located outside the motor housing, the tightening bolt is bent by an impact when an unexpected external force is applied, and the sealing effect between the upper end bracket or the lower end bracket and the motor housing is improved. It may be damaged and water may enter the motor housing.

Instead of the above, the lateral dimension of the upper end bracket and the lower end bracket is increased so that the upper end bracket and the lower end bracket are not related to the watertight seal between the upper end bracket and the lower end bracket. Connect the end bracket with a tightening bolt,
Although it is conceivable to clamp and hold the motor housing between the two end brackets, this configuration inevitably leads to an increase in size of the device.For example, in terms of product transportation, material, and cost. It is disadvantageous in terms. On the other hand, on the outside of the motor housing,
If a notch for inserting the tightening bolt that connects the upper end bracket and the lower end bracket is provided,
Due to this notch, the magnetic path on the stator side is partially blocked, effective magnetic flux cannot be obtained, and the magnetic circuit characteristics of the stator core are impaired. It cannot be adopted due to possible problems such as occurrence.

Thirdly, in the present embodiment, the motor housing 3 is a motor housing made of a stainless steel plate that is drawn and pressed into a tubular shape. Unlike those molded by welding, corrosion cracking does not occur from the welded part due to long-term use in water, excellent watertightness, and no deterioration in life. Further, the drawing process has better dimensional accuracy than the welding process, and can also reduce the cost as compared with the welding process which requires a lot of time and labor. The cost of the motor housing obtained by drawing was able to be reduced by about 10% as compared with the motor housing obtained by processing.

Fourthly, in the present embodiment, as shown in FIGS. 18 to 19, the stator inlet of the motor housing 3 has a large diameter, and a taper portion 3b directed to the rear side is formed. According to the configuration, the large diameter portion functions as a guide for smoothly introducing the stator before the stator is gradually press-fitted along the taper portion 3b of the motor housing 3 and set in the fixed position, When the stator is set, the stator core 1 and the stator winding 2 are attached to the motor housing 3
It is possible to eliminate the problem of being deformed or damaged due to useless collision.

At this time, if a taper is provided only on the inside of the motor housing 3 and the outer circumference of the motor housing 3 has the same outer diameter, a packing 45 for sealing between the motor housing 3 and the upper end bracket 11, Also, parts can be commonly used as the packing 46 that seals between the motor housing 3 and the lower end bracket 12, which is economical.

Fifthly, in this embodiment, in this type of submersible pump, a stator positioning protrusion 3c is provided inside the motor housing 3. According to this construction, the stator is provided inside the motor housing 3. Even if there are variations in the press-fitting force when the press-fitting is performed, it is possible to easily set the press-fitting force at a fixed position and improve the workability of assembling the submersible motor.

Sixthly, in this embodiment, an electric circuit board such as the motor control circuit board 20 is attached to the upper end bracket 11 together with the radiator plate 21 mounted integrally with the electric circuit board.
It is mounted in a pocket portion 11e provided on the side of the underwater motor. According to this configuration, the size of the underwater motor in the height direction can be suppressed, and the underwater motor can be installed around the electric circuit board. The liquid in the tank can be efficiently cooled, and the frequency of troubles caused by the thermal influence of the electric circuit board can be reduced.

At this time, a slope 11f for guiding the electric circuit board / heat sink assembly unit to the fixing groove 47 at the bottom of the pocket is provided on the side wall of the electric circuit board mounting pocket 11e.
By attaching, the positioning work of the electric circuit board / heat sink incorporated unit in the narrow pocket 11e can be performed well.

[0067]

As described above, according to the present invention, a stator, a rotor arranged inside the stator, a cylindrical motor housing fitted to the outer circumference of the stator and surrounding the outer circumference, The upper end bracket and the lower end bracket respectively provided at both ends of the motor housing, and the tightening bolts for tightening the upper and lower end brackets so as to hold the motor housing from both ends are provided. An upper bearing support portion on which an upper bearing that supports the rotation shaft of the rotor fits is provided on a side surface, and a lower bearing that fits a lower bearing that supports the rotation shaft of the rotor on an inner surface of the lower end bracket. In a submersible motor provided with a support portion, a motor circuit board is provided on the outer surface of the upper end bracket, and a slight gap G is separated from the motor circuit board. The FG magnet is fixed to the FG yoke fixed to the rotary shaft so as to face, and the insert (pressing plate) for pressing the upper bearing against the upper bearing support portion is provided on the upper end bracket. According to this configuration, , Even if the bearing causes outer ring creep on the bearing due to friction between the bearing and the upper end bracket on the outer periphery of the bearing due to the phenomenon described above, a "pestle" -like rotary motion is generated in the rotation of the motor rotating shaft. Therefore, it is possible to improve the reliability of the product by eliminating the problem that a pulse drop occurs in the control of the motor rotation detection system.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the internal structure of a pump incorporating a submersible motor according to the present invention.

FIG. 2 is a partially exploded perspective view of FIG.

3 is a partial cross-sectional view in the lateral direction of FIG.

FIG. 4 is a block diagram of a pump drive unit including a motor.

FIG. 5 is an explanatory view of the internal structure showing only the underwater motor in FIG.

6 is a plan view of a motor circuit board 14. FIG.

7 is a plan view of the upper end bracket 11. FIG.

8 is a longitudinal sectional view of FIG.

9 is a bottom view of FIG. 7. FIG.

FIG. 10 is a perspective view of an upper end bracket 11.

11 is a bottom perspective view of the upper end bracket 11. FIG.

FIG. 12 is an exploded perspective view of an upper end bracket 11, a circuit protection cover 22, a motor control circuit board (20) / heat sink (51) built-in unit.

FIG. 13 is a plan view of the circuit protection cover 22.

FIG. 14 is an explanatory diagram of the internal structure of the circuit protection cover 22.

FIG. 15 is a characteristic comparison diagram of a brushless motor and an induction motor.

FIG. 16 is a perspective view of a motor housing 3 showing a second embodiment of the present invention.

FIG. 17 is a plan view of FIG. 16;

18 is a sectional view taken along line AA of FIG.

19 is a view corresponding to FIG. 18, showing a state where the stator of the motor housing 3 is press-fitted.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stator core, 2 ... Stator winding, 3 ... Motor housing, 3a ... Bulging part (protruding part), 3b ... Tapered part, 3c ...
Stator positioning protrusion, 4 ... Motor rotating shaft, 5 ... Rotor yoke, 6 ... Main magnet, 7 ... FG magnet, 8
... FG yoke, 10a ... upper bearing, 10b ... lower bearing,
11 ... Upper end bracket, 11d ... Packing mounting groove, 11e ... Pocket part, 11f ... Gradient, 12 ... Lower end bracket, 14 ... Motor circuit board, 20 ... Motor control circuit board, 21 ... Aluminum heat sink, 43a-4
3c ... water level detection float switch, 44 ... tightening bolt,
45 and 46 ... Packing, 49 ... Insert (holding plate).

Claims (1)

[Claims] 1. A stator, a rotor disposed inside the stator, a cylindrical motor housing that fits on the outer periphery of the stator and surrounds the outer periphery, and both ends of the motor housing. An upper end bracket and a lower end bracket provided respectively, and a tightening bolt for tightening the upper and lower end brackets so as to sandwich the motor housing from both ends, and the rotor is provided on an inner surface of the upper end bracket. An upper bearing support portion to which an upper bearing supporting the rotating shaft of is fitted, and a lower bearing support portion to which a lower bearing supporting the rotating shaft of the rotor is fitted is provided on an inner surface of the lower end bracket. In the submersible motor, a motor circuit board is provided on the outer surface of the upper end bracket so that the motor circuit board faces the motor circuit board with a slight gap G. Water motor secured to FG yoke has a G magnet fixed to a rotating shaft, characterized in that the insert is pressed against the upper bearing in the upper bearing support (pressing plate) is provided in the upper end bracket.