JPH09137794A - Underwater pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable discharge quantity by using a DC brushless motor to generate highly efficient and high starting torque while restraining enlargement of an appearance shape. SOLUTION: An AC-DC electric power source conversion circuit 21 and a motor control circuit 20 to operate a DC brushless motor 1 to drive a pump runner 46 by an AC electric power source are arranged by dividing into a space formed above a head of the DC brushless motor 1 and a space formed along a side part of the DC brushless motor 1 by an end bracket 8 and a circuit protective cover 30. Consequently, enlargement of a shape is restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical submersible pump operated by an AC power source, which is suitable for use in wastewater treatment and the like.

[0002]

2. Description of the Related Art General vertical submersible pumps are
As disclosed in Japanese Patent No. 14591, an induction motor operated by a single-phase or three-phase AC power source is used.
In submersible pumps that use induction motors, it is inevitable that the rotational speed characteristics will change due to different frequencies of the AC power supply, and it is necessary to use pump runners and pump casings that are compatible with the power supply frequency. ,
Since the rotation speed of the induction motor changes due to the load change due to the change of the lift, etc., there is a problem that the fluctuation of the pump flow rate (discharge amount) becomes large.

On the other hand, it has been proposed to use a DC brushless motor for a deep well submersible pump. Since this well submersible pump has a DC power source drive system,
When operating in an environment where only C power is available, AC-
It is necessary to prepare a DC power converter, which is problematic in terms of usability.

[0004]

The induction motor can be operated at an arbitrary rotation speed that is not affected by the frequency of the AC power source by performing feedback control by adding a control circuit such as an inverter control. There is a problem that the submersible pump becomes large due to the addition of the control circuit. Moreover, the induction motor has a problem that it cannot obtain a high starting torque.

D that can generate a large starting torque with high efficiency
In order to be able to operate the submersible pump using the C brushless motor by using the AC power supply, the AC-DC power supply conversion device must be built in, and there is a problem that the size becomes large.

It is an object of the present invention to realize a submersible pump which can obtain a stable discharge amount by using a DC brushless motor which produces a high efficiency and a high starting torque while suppressing an increase in the external shape. Is.

[0007]

The present invention uses a DC brushless motor capable of generating a large starting torque, and an AC-DC power supply conversion circuit and a motor control for operating the DC brushless motor with an AC power supply. In order to suppress the enlargement of the shape by incorporating a circuit and efficiently incorporating the AC-DC power supply conversion circuit and the motor control circuit,
The AC-DC power supply conversion circuit and the motor control circuit are divided into a space formed above the DC brushless motor and a space formed along the side portion of the DC brushless motor.

The DC brushless motor uses an inversion type that easily dissipates heat, and the motor case made of a steel plate that houses the stator core is exposed to water for cooling.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the submersible pump according to the present invention comprises a motor section 110 as a center, a pump section 120 connected to the lower side thereof, and a control section 130 connected to the upper side thereof.

The motor section 110 is composed of an inner rotor type DC brushless motor, as will be described in detail with reference to FIGS. As shown in FIG. 2, the stator portion of the inner rotor type DC brushless motor 1 is configured such that the stator winding 3 is wound in a slot formed in the inner circumference of the stator core 2 through an electric insulator. The stator core 2 is press-fitted and fastened to a motor frame 4 made of a stainless steel plate in consideration of mechanical strength, water resistance and heat dissipation.
The rotor portion is configured by press-fitting and fastening a rotor yoke 6 onto a motor rotating shaft 5, and adhering and fixing a main magnet 7 that generates a magnetic field to the rotor yoke 6 with an adhesive or the like. The end brackets 8 and 9 made of synthetic resin are fitted with through bolts 10 so as to sandwich both ends of the motor frame 4.
The motor rotating shaft 5 is fastened by the ball bearing 11
It is rotatably supported by a and 11b. An FG yoke 13 to which an FG magnet 12 that generates a magnetic field for forming a frequency generator (FG) is adhered with an adhesive or the like is fastened to an end of the motor rotation shaft 5 by a lock nut 14.

Next, in accordance with the rotational position of the magnetic pole of the main magnet 7 in the DC brushless motor 1, the rotational position detecting means by the hall element for controlling the switching of the phases of the power feeding to the stator winding 3 and the rotation. The FG for detecting the rotation speed for speed control will be described.

As shown in FIG. 3, an FG coil pattern 16a and a lead pattern 16b soldered to the Hall elements 17a to 17c are formed on a motor circuit board 15 made of a composite material such as copper foil and paper phenol. Are formed of copper foil, and the motor cable 18 is connected to them. The motor circuit board 15 has a fixing screw 1 which penetrates the mounting hole 15a and is screwed into the end bracket 8.
It is fixed to the end bracket 8 by 9.

In the state in which the stator portion and the rotor portion are combined, the FG coil pattern 16a has the FG magnet 12 so that the magnetic field of the FG magnet 12 acts.
And a magnetic field of the FG magnet 12 rotates with the rotation of the motor rotation shaft 5 to induce a voltage having a frequency corresponding to the rotation speed and output it as a rotation speed signal. To do. Hall element 1
Similarly, 7a to 17c also have the FG magnet 12 of the rotor portion.
So as to act on the FG magnet 12 through a minute gap so that a magnetic pole position detection signal is generated and fixed when the magnetic pole of the main magnet 7 faces a predetermined phase of the stator winding 3. It is supplied as a control timing signal for controlling the switching of the power feeding phase of the subsidiary winding 3 to continuously generate the rotating torque.

Next, DC power is generated from the AC power and D
An electric circuit configuration of the control unit 130 for switching the feeding phase of the drive current flowing through the stator winding 3 of the C brushless motor 1 and controlling the rotation speed will be described with reference to FIG.

The electric circuit is basically a motor control circuit section 20 for controlling the feeding phase switching of the stator winding 3 in the DC brushless motor 1, rotation speed control and overload protection, and an AC power source for the DC power source. And an AC-DC power conversion circuit section 21 for converting into
Connected to C power supply 23, float switch cable 24
Connected to the float switches 25a to 25c via
Further, in the submersible pump, it is connected to the DC brushless motor 1 via the motor cable 18.

The motor control circuit section 20 includes an overload protection circuit 20a for monitoring the load state to prevent an overload state, a dedicated IC and a microcomputer, and is provided for the stator winding 3. A control IC 20b for performing power feeding phase switching control and rotation speed control, and a motor driver 20c for interrupting the winding current are provided. And
The AC-DC power supply conversion circuit unit 21 includes a rectification unit 21a that rectifies an AC voltage, a smoothing circuit 21b that smoothes a pulsating current obtained by rectification, and a switching regulator 21c.

The AC-DC power conversion circuit section 21 is mounted on the power circuit boards 26a and 26b, and the motor control circuit section 20 is mounted on the control circuit board 27. The power supply phase switching control transistor (motor driver) 20c in the motor control circuit section 20 is attached to the aluminum heat dissipation plate 28 for heat dissipation and connected to the control circuit board 27. The aluminum heat dissipation plate 28 is formed by combining a horizontal plate and a vertical plate into a substantially T-shaped cross section, and
a and 26b are mounted on the horizontal plate portion, and the control circuit board 27 is mounted on the vertical plate portion. Then, the power supply circuit boards 26a and 26b on which the AC-DC power supply conversion circuit section 21 is mounted are positioned horizontally above the DC brushless motor 1, and the control circuit board 27 on which the motor control circuit section 20 is mounted is the DC brushless motor 1. The aluminum heat radiating plate 28 is fixed to the end bracket 8 by a fixing screw 29 so that the aluminum heat radiating plate 28 is vertically positioned along the side surface of the. However, the motor control circuit unit 20 and the AC-DC power supply conversion circuit unit 21 can be partially mounted on a common circuit board.

Next, a description will be given of an outer structure in which the motor section and the circuit section are used as a submersible pump to normally operate under water and maintain functionality. With respect to the submersible pump, weight reduction and watertightness (airtightness) are important factors in product structure as well as improvement of pump performance. The outer components except the motor frame 4 are formed by molding a synthetic resin that can withstand various water qualities.

As shown in FIGS. 5 and 6, the end bracket 8 has a centering protrusion 8a for alignment with the motor frame 4, a bearing mounting portion 8b for mounting the ball bearing 11a, and the through bolt. A through hole 8c for passing through 10, a screw hole 8d for fixing the motor circuit board 15, a projection 8e with a screw hole for mounting the aluminum heat sink 28, and a joint surface with a circuit protection cover 30 described later. A rubber ring mounting groove 8f for mounting a watertight securing rubber ring to make a watertight state, a through hole 8g for penetrating a coupling bolt for coupling the end bracket 8 and the circuit protection cover 30, and a vertical plate of the aluminum heat sink 28 and its portion. Mounted control circuit board 27 (motor control circuit unit 2
0) is provided with a motor control circuit unit accommodation space 8h extending along the outer side of the DC brushless motor 1.

As shown in FIG. 1, the circuit protection cover 30 is attached to the end bracket 8 and is fastened by a coupling bolt 31 and a coupling nut 32 to be supported by a watertight holding rubber ring 33 to support the Ed bracket 8. Bond in a watertight condition.

This circuit protection cover 30 is shown in FIGS.
As described in detail below, a handle 30a for transporting and installing the submersible pump, a post screw hole 30b for attaching a post for a float switch, and the AC-DC power supply conversion circuit unit 21 receives power from an external AC power supply. The power supply cable 22 and the motor control circuit section 20 for inputting the float switch cable 24 for inputting the water level detection signal from the water level detection float switches 25a to 25c penetrate the circuit protection cover 30 while maintaining the watertightness. Cable through holes 30c, 30d and set screw holes 30e, 3 for
With 0f.

The detailed structure of the cable outlet portion will be described with reference to FIG. The penetrating portions of the power supply cable 22 and the float switch cable 24 penetrating the circuit protection cover 30 are provided with flanged output rings 34 and 35 integrally formed with the power supply cable 22 and the float switch cable 24 by a rubber material, This each ring 3
4, 35 are through holes 30c, 30d of the circuit protection cover 30.
The circuit protection cover 3 by inserting the collars 34a, 35a into the circuit protection cover 3
Fixing screw 38 in which the metal sealing caps 36 and 37, which are in contact with the outer surface of 0 and are respectively in contact with the outer surfaces thereof, are screwed into the lead-out portion set screw holes 30e and 30f provided in the lead-out portion of the circuit protection cover 30. , 39 to tighten the collar 34a, 3
The water-tightness is obtained by closely adhering 5a with the elasticity of rubber. The support column 40 is fitted into the support column screw hole 30b, stands up from the circuit protection cover 30, and supports the float switches 25a to 25c.

As shown in FIG. 1, the intermediate casing 41 is joined to the bottom of the end bracket 9 by a fixing screw 43 so as to penetrate the motor rotating shaft 5 with a mechanical seal 42 interposed, and the joining surface is O-shaped. Ring 4
By forming a watertight structure by 4, the mechanical seal protective oil chamber 45 in a hermetically sealed state is formed around the mechanical seal 42.

The pump section 120 is a vortex type pump. The pump runner 46 has a fixing screw 47 attached to the shaft end of the motor rotating shaft 5 penetrating the intermediate casing 41.
Fixed by The upper pump casing 48 and the lower pump casing 49 are coupled to the lower side of the intermediate casing 41 by casing coupling screws 50 and 51 to form a pump chamber that accommodates the pump runner 46. A suction hole 49a is formed in the pump lower casing 49,
The upper pump casing 48 is provided with a flange 52 having a male screw portion for connecting a pipe.

The components constituting these are also formed by molding the same synthetic resin as the end bracket 8 and the circuit protection cover 30.

The submersible pump thus constructed is connected (distributed) to the flange 52 and put (installed) in the water to be drained. The AC-DC power conversion circuit unit 21 converts the AC power received via the power cable 22 into a DC power. Then, the motor control circuit 20 uses the DC power supply to detect the water level detection float switches 25a to 25c.
DC brushless motor 1 referring to the water level detection signal from
The drainage operation is executed by turning on / off the power supply to (3) operation (stop and operation).

The motor characteristics of the DC brushless motor 1 in this submersible pump and the induction motor in the conventional submersible pump are shown in comparison with FIG. DC brushless motor 1
The characteristic is that the torque and the rotation speed change linearly when the rotation speed is not controlled (state where the rotation speed is not controlled), and the torque at the time of "0", that is, the torque at the time of startup becomes maximum. Therefore, it is possible to improve the starting performance by increasing the torque at the time of starting. Further, unlike the induction motor, the maximum rotation speed can be arbitrarily set depending on the magnetic flux of the main magnet 7 and the specifications of the stator winding 3, and a desired rotation speed can be obtained without being influenced by the frequency of the AC power supply. be able to.

Therefore, the control I of the motor control circuit section 20
If the C20b uses the rotation detection signal from the FG to control the rotation of the DC brushless motor 1 at a constant speed, the rotation speed can be kept constant with respect to a change in the load torque within a certain range. If constant speed control is performed, it is possible to reduce the amount of change in the pump discharge flow rate by maintaining the rotation speed at a constant speed with respect to changes in load due to changes in head and the like. Further, if feedback control is performed to make the pump discharge flow rate constant, a constant discharge amount can be stably obtained regardless of the height of the head. Furthermore, the overload protection circuit 2
By providing 0a with a protection control function such as a current limiter, it is possible to perform a safety protection operation such as stopping the motor at the time of overload.

In the inversion type DC brushless motor 1, the motor frame 4 made of stainless steel plate, into which the stator core 2 having the stator winding 3 having a large amount of heat generation is press-fitted, is exposed to water and radiates heat efficiently. The temperature rise can be suppressed.

Further, the length of the submersible pump is increased due to the increase in the axial length due to the use of the inner rotor type DC brushless motor 1, so that the motor control circuit portion 20 is controlled to extend to the side portion of the DC brushless motor 1. Circuit part accommodation space 8h
It has been installed and suppressed.

[0032]

As described above, in the submersible pump of the present invention, by using the DC brushless motor as the drive motor, the efficiency is high, the starting torque is high, and the constant discharge amount is stable regardless of the height of the head. can get.

In addition, an AC-DC power supply conversion circuit unit is incorporated to enable operation by using an AC power supply, thereby increasing the size of an electric circuit and increasing the length by using an inversion type DC brushless motor. Since a part of the electric circuit is installed and absorbed in the motor control circuit unit accommodation space that extends to the side of the DC brushless motor, it is possible to suppress the increase in size in the height direction.

Further, since the stator iron core having the stator winding which generates a large amount of heat is exposed to water by exposing the motor frame made of steel plate to water, the temperature rise can be suppressed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a submersible pump according to the present invention using a DC brushless motor.

FIG. 2 is a vertical sectional side view of a motor unit in the submersible pump shown in FIG.

FIG. 3 is a plan view of a motor circuit board in the motor section shown in FIG.

FIG. 4 is a block diagram of a control unit including a DC brushless motor in the submersible pump shown in FIG.

5 is a plan view of an end bracket of a motor unit of the submersible pump shown in FIGS. 1 and 2. FIG.

6 is a vertical sectional side view of the end bracket shown in FIG.

FIG. 7 is a plan view of a circuit protection cover in the submersible pump shown in FIG.

8 is a vertical sectional side view of the circuit protection cover shown in FIG.

9 is a vertical sectional side view showing a detailed configuration of a circuit protection cover cable outlet portion in the submersible pump shown in FIG.

FIG. 10 is a characteristic comparison diagram of a DC brushless motor and an induction motor.

[Explanation of symbols]

 1 Inner rotation type DC brushless motor 2 Stator iron core 3 Stator winding 4 Motor frame 5 Motor rotating shaft 7 Main magnet 8, 9 End bracket 20 Motor control circuit section 21 AC-DC power conversion circuit section 30 Circuit protection cover 46 Pon Planner 48 Pump upper casing 49 Pump lower casing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fusunori Ohira 1-1-1 Higashitaga-cho, Hitachi-shi, Ibaraki Hitate Taga Engineering Co., Ltd.

Claims (3)

[Claims] 1. A submersible pump including an AC-DC power supply conversion circuit and a motor control circuit, wherein a pump section is driven by a DC brushless motor, wherein the AC-DC power supply conversion circuit and the motor control circuit are D
A submersible pump characterized by being divided into a space formed above the head of the C brushless motor and a space formed along the side of the DC brushless motor. 2. The submersible pump according to claim 1, wherein the DC brushless motor is an inner rotor type, and a stator core of the DC brushless motor is installed in a motor frame made of a steel plate exposed to water. 3. The end bracket formed of synthetic resin, which is coupled to an end of a motor frame of the DC brushless motor, and a circuit protection are provided in a space for accommodating the AC-DC power supply conversion circuit and the motor control circuit. A submersible pump characterized by being formed by a cover.