JPH08107652A - Drive of synchronous electric motor - Google Patents

Abstract

PURPOSE: To achieve rotary activation in a constant direction and at the same time obtain a required torque by regulating the drive force transmission and rotary direction with one cylindrical coil spring. CONSTITUTION: A diameter (b) of a through hole 4 drilled at the center of a load member is larger than a diameter (a) of a drive shaft 2 and the through hole 4 is loosely engaged when it passes through the drive shaft 2. Also, the inner diameter of a coil spring 5 is slightly smaller than the diameter of the drive shaft 2 in still state and is engaged into the drive shaft 2 while the diameter increases. Then, one edge of the coil spring 5 is gear-locked to the load member 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a synchronous motor, and more particularly to a drive device in which a coil spring is wound around a drive shaft.

[0002]

2. Description of the Related Art As a drive unit of a conventional synchronous motor, there is one shown in FIG. In the figure, 31 is a stator core, 32 is a permanent magnet rotor, a drive coil 34 is attached to a magnetic path piece 33 of the stator core 31, and a permanent magnet rotor 32 is provided above and below the magnetic poles. A bearing body 36 for rotatably supporting is fixed, and when an alternating current is applied to the drive coil 34, an alternating magnetic field is generated in the magnetic pole portion, and the alternating magnetic field activates the permanent magnet rotor 32. , The drive shaft 35 is rotated to shift to synchronous rotation. This type of synchronous motor has the advantages of high efficiency, simple structure, and high output, but the rotation direction is undefined each time it is started, and it cannot be set in one direction, and the starting torque is small. However, it has a drawback that it becomes impossible to start when a load is connected to the drive shaft, which restricts the use of the synchronous motor in various rotary devices and is inefficient even if the synchronous motor can be used. I am trying.

For example, a driving synchronous motor of the above principle is used to rotate blades that perform a pumping action on power equipment such as a water supply pump device. In this pump device, as shown in FIG. 4 (b), the vane and the pump casing 3 (not shown) are provided so that the pump action can be performed regardless of whether the drive shaft rotates leftward or rightward, and the load at startup is reduced.
A play section of about 180 ° is provided between the drive shaft 8 and 8, and a drive shaft (not shown) is started in this play section, and then the water flow is pressurized by the blades. This shape overcomes a large amount of water inertia and thus requires a large start-up torque, which not only increases the size of the electric motor, but also causes a collision noise at the boundary between the play section and the pressurization section. Moreover, the collision sound continues until the uniform speed is reached. In addition, since the rotation direction cannot be regulated, the pump structure becomes a bidirectional rotation type, and the pump efficiency cannot be improved.

Therefore, in Japanese Patent Publication No. 4-24943, a boss 19 which is rotatably loosely fitted is inserted into the drive shaft 16 as shown in FIGS. ing. Further, a conical torsion spring 21 including a conical portion 21a, a small diameter coil portion 21b and a large diameter coil portion 21c is inserted into the drive shaft. The small diameter coil portion 21b is attached to the drive shaft 16, and the large diameter coil portion 21c is attached to the boss 1.
It is press-fitted into 9 and wound. As a result, the boss having the blades 20 and the drive shaft are resiliently connected via the conical torsion spring 21. A clutch spring 22 which allows only one-direction rotation is wound around the boss in FIG. 5, and the other end 22b of the clutch spring is wound around a pin 24 standing on the bearing body 18 in parallel with the drive shaft. It is fixed. In another embodiment shown in FIG. 6, a boss 19 is also provided with a clutch spring 23 which allows rotation only in a fixed direction, and the other end 23b of the clutch spring is fixed to the boss portion 25 of the bearing body 18 with a screw. ing.

Small diameter coil portion 21 of conical torsion spring 21
b and the large-diameter coil portion 21c are tightly wound around the drive shaft 16 and the boss 19 so as not to slip in a certain direction of the drive shaft. Then, the conical torsion spring is displaced so as to enlarge the large-diameter coil portion 21c with respect to the rotational vibration in the B direction in the drawing. On the other hand, in the anti-B direction, the conical torsion spring is in the winding tightening direction, and as a result, the rotational force concentrates on the conical portion 21a which can be wound. When the same rotational vibration force acts, a difference occurs in the rotational displacement angle between the B direction and the anti-B direction, and the displacement angle in the B direction becomes large. Therefore, since the displacement angle of the permanent magnet rotor increases in the B direction as the rotational vibration increases, the permanent magnet rotor starts in the B direction and then shifts to the synchronous rotation.

In the conventional structure as described above, the conical torsion spring for transmitting the rotational movement of the drive shaft needs to be formed with the small diameter coil portion 21b, the large diameter coil portion 21c and the conical portion 21a, and the spring has this shape. It requires special jigs and tools to form. Further, a clutch spring is required in addition to the conical torsion spring, and the boss always slides on the clutch spring even during synchronous rotation, resulting in a torque load.

[0007]

In view of the above situation, the present invention has one tubular coil spring for transmitting the driving force and restricting the rotational direction, and further, in the thrust direction at a position away from the end surface of the load member. By providing the regulating member on the drive shaft, the rotation is surely started in a fixed direction. As a result, a highly economical drive device for a synchronous motor is provided.

The drive device of the present invention can be applied to various load members, but is particularly useful as a drive synchronous motor for rotating the blades of a water feed pump device or the like. By installing this drive device, not only can the pump device have the required start-up torque but the electric motor can be made smaller, and collision noise can be prevented. Moreover, since the rotation direction is restricted to a fixed direction, pump efficiency can be improved. Therefore, not only the cost of the drive device itself is high, but also the cost of the pump device can be reduced.

[0009]

In view of the above-mentioned problems, in the drive device for a synchronous motor of the present invention, the drive shaft of the synchronous motor and the through hole of the load member penetrating the drive shaft have a loose fitting relationship.
A gist of the present invention is that a coil spring having a diameter slightly smaller than that of the drive shaft is fitted into the drive shaft, and one end of the coil spring is locked to an end surface of the load member.

[0010]

A coil spring having a diameter smaller than that of the drive shaft is wound around the drive shaft, and one end of the coil spring is locked to the load member, so that the coil spring starts to rotate in a fixed direction when the coil spring is started. At the same time, the load member is continuously rotated by the winding force of the coil spring.

When the drive device of the present invention is used to rotate a blade such as a water supply pump device as a load member,
By setting the winding force of the coil spring, that is, the tightening force, to a desired value, the pump device can easily obtain the required starting torque and rotation torque. In addition, since the winding force of the coil spring is exceeded when the load member is overloaded, the drive shaft idles and safety is ensured.

[0012]

1 is a side view of an embodiment of a drive device for a synchronous motor according to the present invention, FIG. 2 is a side view of a main portion thereof, and FIG. 3 is a plan view corresponding to FIG. In the figure, 1 is a synchronous motor that serves as a drive source, 2 is a drive shaft, 3 is a load member in which blades 11 that constitute, for example, a water flow pump are formed, and 4 is the load at which the drive shaft 2 is fitted. Through hole formed in the center of the coil spring, 5 is a coil spring, 6 is a spring locking portion formed by inserting one end of the coil spring into a hole formed in the lower end surface of the load member, and 7 is to the synchronous motor 1 side. Is a first restricting member that restricts the movement of the blades and slidably holds the other end of the coil spring, and is composed of a washer 9 and the like locked to the drive shaft 2. The washer 9 is fixed to the drive shaft 2 with a retaining ring 8 such as an E ring. Reference numeral 10 denotes the other end of the drive shaft, which is a second restricting member 12 including a retaining ring such as an E ring.
Is fixed to the drive shaft 2 in order to prevent the load member 3 from coming off the drive shaft 2. Reference numeral 13 is a sliding surface between the first regulating member 7 and the other end of the coil spring 5.

In the above construction, the diameter b of the through hole 4 formed in the central portion of the load member 3 is slightly larger than the diameter a of the drive shaft 2, and when the drive shaft 2 is penetrated through the through hole 4. It is loosely fitted. The inner diameter of the coil spring 5 is formed to be slightly smaller than that of the drive shaft 2 in a stationary state, and the coil spring 5 is inserted into the drive shaft 2 while expanding its diameter. One end thereof is slidably held by the locking portion 6, and the other end is slidably held by the sliding surface 13 of the first regulating member 7.

E-shaped retaining rings or the like can be used as the retaining rings 8 and 12. The E-shaped retaining ring is locked to the drive shaft 2 in a conventional manner. The washer 9 is for preventing the other end of the coil spring from being entangled with the cutout portion of the E-shaped retaining ring and allowing it to slide. Therefore, if slidability is guaranteed, the washer 9
The state where the above is removed, that is, the sliding surface 13 may be formed by the other end of the coil spring and the retaining ring 8. Other types of regulating members can be used as long as they serve this purpose.
Alternatively, the drive shaft may be provided with a large-diameter portion to form a stepped portion, and the other end of the coil spring 5 may be held at this stepped portion, or a color may be further press-fitted to be held.

In the above embodiment, the first regulating member 7
The coil spring 5 is placed between the lower end surface of the load member and the synchronous motor 1, and the coil spring 5 is inserted between them. Conversely, the coil spring 5 is inserted between the second restricting member 12 and the load member 3. The same effect can be obtained.

When the drive shaft 2 is rotated by energizing the synchronous motor 1 with the above-described structure, the coil spring 5 easily rotates in the loosening direction, but in order to rotate the coil spring in the tightening direction, the drive shaft 2 rotates. Since a torque for rotating the load member 2 and the load member 3 at the same time is necessary, it is impossible to rotate due to an overload in this direction. That is, the spring is rotatable in only one direction with respect to the rotation axis. As a result, when the synchronous motor 1 is energized, the drive shaft 2 rotates in the direction in which the coil spring 5 loosens. At this time, the rotating force of the drive shaft 2 is applied to the coil spring and the load member 3 due to friction generated by the coil spring.
Is transmitted and the load member 3 is rotated.

Moreover, in the initial stage of energization, the load through hole 4 and the drive shaft 2 are loosely fitted to each other, and the load member 3 and the drive shaft 2 are engaged with each other via the coil spring.
Even if a load is applied to the coil spring, the coil spring can be driven only by the torque in the slackening direction. Also,
When the load member is overloaded, slippage occurs beyond the range of the coil spring winding force, and the drive shaft 2 idles.

FIG. 4 (a) is a plan view of a water feed pump when the drive device of the present invention is used for the water feed pump in contrast to FIG. 4 (b). In the figure, 26 is a discharge port and 27 is a suction port. The mouth 28 is a casing. A stator of a synchronous motor (not shown) causes a magnetic action by applying an electric current to rotate the rotor, and a drive shaft (not shown) fixed to the rotor also rotates. By setting the frictional force generated by the winding force of the coil spring to a value that ensures the torque required for the pump when the load against water applied to the blade (not shown) of the load member is rotated at a constant speed, A desired internal pressure is applied during the period, the water supply pump rotates in a stable state, and water is discharged from the discharge port 26.

In the above description, an example of using it in a water feed pump has been described, but the load member to be driven is not limited to the blade of the water feed pump, but can be applied to various devices having a large inertial load as a synchronous motor.

[0020]

As described above, the drive device for a synchronous motor according to the present invention is rotated in a direction in which the coil spring is wound and loosened at the time of starting and gradually follows the drive shaft, and is finally driven by the winding force of the coil spring. Since the shaft and the load member rotate at a constant speed, the starting torque of the electric motor can be reduced. Therefore, the motor rotor can be downsized, and the startup load of the rotor inertia can be reduced. For example, when the present device is used for a water feed pump, the acceleration of the water flow can be reduced, so that the output of the electric motor can be reduced, and thus the synchronous motor may be small.

When the coil spring rotates in the tightening direction, the acceleration load of the load member is much larger than when the coil spring rotates in the loosening direction, so that the motor is a one-way rotating electric motor. For example, when this device is used for a water supply pump, the electric motor rotates in one rotation direction, so that the blade, casing, and discharge port can be formed into a generally efficient shape. In addition, there is no collision noise and you can drive quietly.
As a result, the electric motor rotates stably for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a drive device for a synchronous motor of the present invention.

FIG. 2 is a side view of the essential parts of an embodiment of a drive device for a synchronous motor of the present invention.

FIG. 3 is a plan view corresponding to FIG. 1 of the present invention.

FIG. 4A is an example of a water supply pump using the synchronous motor drive device of the present invention, and FIG. 4B is an example of a conventional water supply pump using the synchronous motor drive device.

FIG. 5 is a side view of an embodiment of a conventional synchronous motor drive device.

FIG. 6 is a side view of another embodiment of a conventional synchronous motor drive device.

FIG. 7 is a side view showing a drive unit of a conventional synchronous motor.

[Explanation of symbols]

 1 Synchronous Motor 2 Drive Shaft 3 Load Member 4 Through Hole 5 Coil Spring 6 Locking Part 7 First Regulation Member 13 Sliding Surface

Claims (1)

[Claims] 1. A drive shaft of a synchronous motor and a through hole of a load member penetrating the drive shaft have a loose fitting relationship, and a coil spring having a diameter slightly smaller than that of the drive shaft is inserted into the drive shaft. A drive device for a synchronous motor, wherein one end of the motor is locked to the end surface of the load member.