KR20070058870A - Core in electric motor - Google Patents

Abstract

A core in an electric motor is provided to reduce vibration generated from core when driving motor by forming a groove on a magnet facing a plane of a rotor core. A core in an electric motor includes a magnet(16), a core(30), and a driving shaft(20). The core(30) is installed in a cylindrical space provided by the magnet(16). The driving shaft(20) is installed on a rotation center of the core(30). The core(30) applies a rotation torque to the driving shaft(20) by rotating on an axis by an interaction with the magnet(16) with electricity supplied from the exterior. A magnet facing plane(30c) of the core(30) has two grooves(30d) which increase an average separation distance of the magnet facing plane(30c) from the magnet(16).

Description

Core in electric motor

1 is a plan sectional view of an electric motor shown in order to explain the configuration of a conventional core.

FIG. 2 is an enlarged view of a portion of the electric motor illustrated in FIG. 1.

3 is a plan sectional view of an electric motor provided with a core according to an embodiment of the present invention.

4 is a perspective view of the core shown in FIG. 3.

FIG. 5 is a diagram illustrating an example of a vibration detecting device configured to identify vibration characteristics generated from the electric motor shown in FIG. 3.

FIG. 6 is a diagram illustrating torque characteristics of a motor measured by using the vibration detector of FIG. 5. FIG. 6A is a torque characteristic of a conventional general motor, and FIG. 6B is a built-in core of the present invention. This image captures the screen displaying the torque characteristics of the motor.

<Explanation of symbols for the main parts of the drawings>

14: Casing 16: magnet

18: Core 18a: Coil winding unit

18b: space part 18c: magnet facing side

18e: core slot 18x, 18y: magnet facing side

20: Drive shaft 30: Core

30c: magnetic facing side 30d: groove

A: Motor B: Belt C: Torque detector D: Measuring motor

M: Permanent magnet

The present invention relates to a core of an electric motor.

The stator and the rotor are provided inside the casing of the electric motor. The stator includes a plurality of permanent magnets fixed to the inner wall of the casing, a brush for applying external electricity into the motor, and the like. The permanent magnet is symmetrical about the center of rotation of the rotor and forms a cylindrical space therebetween.

In addition, the rotor is rotatably installed in the inner cylindrical space provided by the permanent magnet, the outer peripheral surface of the core facing the permanent magnet, a drive shaft fixed to the central axis of rotation of the core, and to the core 18 Coils (not shown) wound around the core to induce electromagnetic, and a commutator (not shown) for transmitting external electricity to the coil.

The core is roughly cylindrical (although it depends on the specification and type of the motor) and its outer circumferential surface is positioned opposite to the inward face of the permanent magnet, and acts as a permanent magnet and rotates as the electromagnetic force is induced. In particular, the outer circumferential surface of the core is separated at equal intervals by a plurality of slits parallel to the longitudinal direction of the drive shaft.

1 is a plan sectional view of an electric motor schematically shown to explain the configuration of a conventional core.

As shown, four magnets 16 are fixed to the inner wall surface of the casing 14 of the electric motor, and a core 18 is provided in the interspace provided by the magnets 16.

The core 18 has a cylindrical shape as a whole, and a drive shaft 20 is fixed to the center of rotation thereof. In addition, as described above, core slots 18e extending in parallel with the drive shaft 20 and having a predetermined width are formed on the outer circumferential surface of the core 18 at equal intervals.

Moreover, the space part 18b is provided in the core 18 in the inner direction (from the core slot to the drive shaft direction) of the core slot 18e. Between the space portion 18b and the space portion is a coil winding portion 18a wound by a coil, and the space portion 18b is a passage through which a coil (not shown) passes upward or downward. A plurality of divided magnet opposing surfaces 18c are formed on the outer circumferential surface of the core 18 by the core slot 18e. Each of the magnet opposing surfaces 18c takes the form of a partial cylinder and is pulled toward the magnet 16 side.

In the motor having the above configuration, when electricity is applied to the coil, an electromagnetic force is induced to the core 18, and the core 18 rotates in the direction of the arrow c or vice versa according to Fleming's left hand law.

FIG. 2 is an enlarged view of a portion of the electric motor illustrated in FIG. 1.

As shown, it can be seen that the magnetic force of the magnet 16 extends into the core 18 through the magnet opposing surface 18c of the core 18 and the coil winding 18a. Basically, the core 18 is made of a metal attached to the magnet so that each magnet opposing surface 18c is pulled toward the magnet 16 side. However, as shown in FIG. 1, since the core 18 is symmetrical and the poles of the magnet 16 are also arranged symmetrically, there is no fear that the core 18 will be oriented to one side.

On the other hand, when the core having the above configuration is rotated, the core 18 vibrates due to the rotation. This is a phenomenon because the core slot 18e is formed on the outer circumferential surface of the core 18.

The relationship between the force of the magnet 16 and the magnet opposing surface 18c when the core 18 is rotated in the direction of the arrow c, for example, by applying electricity to the core 18 will be considered microscopically.

As shown in Fig. 2, four magnet opposing surfaces 18c and 18x face the inner region of the magnet 16 and are pulled in the direction of the arrow f2. The magnet opposing surfaces 18c, 18x and the magnet opposing surfaces 18y to be described later are all the same, and for convenience of description, the symbols are divided into 18c, 18x, and 18y. The magnet opposing surfaces 18y on both sides of the four magnet opposing surfaces 18c and 18x are located in the outer region of the magnet 16, and the magnetic force in the direction of arrow f1 between the two mutually neighboring magnets 16 Is getting. It goes without saying that the magnetic force f1 on the magnet opposing face 18y is smaller than the magnetic force f2 on the other magnet opposing faces 18c and 18x.

In this state, when the external force is applied to move the core 18 in the direction of the arrow c (the distance at which the magnet facing surface 18y first enters the inner region of the magnet 16), the magnet facing surface 18y becomes the magnet 16 The magnetic field in the direction of f2 enters the inner region of) and the magnet facing surface 18x in the inner region falls into the outer region and receives the force in the direction of arrow f1.

However, in the case of moving the core 18 by one pitch as described above, since the force of f2 is larger than f1, the core 18 does not try to rotate at first. However, as the core 18 rotates due to an external force, the magnet opposing face 18x gradually moves away from the magnet, and the other magnet opposing face 18y approaches the magnet, and the force not to move gradually weakens.

When the core continues to rotate, the moment that the magnetic force applied to the magnet opposing face 18x and the magnetic force applied to the other magnet opposing face 18y becomes equal, and after that moment, the attraction force to the magnet opposing face 18y becomes larger to apply external force. If not, the core 18 tries to stop after half pitch movement by the magnetic force. Thus, the property of stopping is a cause of generating a fine vibration. This phenomenon occurs even when the core 18 is driven at a high rotational speed.

The vibration generated from the core when driving the motor as described above is transmitted to the outside of the motor through the drive shaft as well as the casing of the motor. Therefore, in the case of precision instruments or various measuring instruments, which are very sensitive to vibration, the operation precision may be poor due to the minute vibration from the motor used.

The present invention has been made to solve the above problems, and by forming a groove of a predetermined shape on the magnet opposing surface of the rotor, the vibration generated from the core during the driving of the motor is reduced as well as the weight is light, so that the power consumption can be reduced when starting. The purpose is to provide a core of an electric motor.

In order to achieve the above object, the present invention, the outer peripheral surface of the magnet provided on the inner wall surface of the casing of the electric motor, but has a magnet opposing surface divided by a plurality of core slots and rotates by electricity supplied from the outside In the core of the motor,

The magnet opposing surface is characterized in that at least one groove is formed.

In addition, the groove extends in a direction orthogonal to the direction of rotation of the core, characterized in that it has a predetermined width and depth.

Hereinafter, one embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a plan sectional view of an electric motor having a core 30 according to an embodiment of the present invention.

The same reference numerals as the above reference numerals denote the same members having the same function.

Referring to the drawings, it can be seen that the core 30 is installed in the cylindrical interspace provided by the magnet 16, and the drive shaft 20 is provided at the center of rotation of the core 30. The core 30 receives electricity from the outside and rotates the shaft by interaction with the magnet 16 to apply rotation torque to the drive shaft 20.

Two grooves 30d are formed in the magnet facing surface 30c of the core 30. As shown in FIG. 4, the grooves 30d are formed side by side on the respective magnet opposing surfaces 30c and increase the average separation distance of the magnet opposing surfaces 30c with respect to the magnet 16. That is, by forming the groove 30d as described above, the average separation distance of the magnet facing surface 30c with respect to the magnet 16 increases.

The separation distance is related to the strength of the magnetic force applied to the magnet facing surface 30c from the magnet, and the separation distance increases even if the number of the grooves 30d increases or the width or depth of the groove increases. When the separation distance increases, the magnetic force applied to the magnet opposing surface 30c becomes small.

The smaller the magnetic force of the magnet 16 applied to the magnet opposing surface 30c, the easier the core is to move one pitch as described above, and the smaller the magnitude of vibration generated at the end of one pitch movement. However, since the area projected onto the magnet 16 of the magnet opposing surface 30c is not reduced, the induced magnetic force of the core 30 induced by the coil is not changed, so that a decrease in torque does not occur.

4 is a perspective view of the core shown in FIG. 3.

As shown, two rows of grooves 30d are formed in each of the magnet opposing surfaces 30c which are divided at equal intervals by the core slots 18e as the outer circumferential surface of the core 30 and located opposite to the magnets 16. It is. Of course, the number or shape of the grooves 30d can be modified as much as the case may be.

FIG. 5 is a diagram illustrating an example of a vibration detecting device configured to identify vibration characteristics generated from the electric motor shown in FIG. 3. Such a vibration detecting device is known.

Referring to the drawings, the torque detector C is connected to the measurement motor D to which the core 30 according to the present embodiment is applied, and the torque detector C is connected to the motor A through the belt B. It can be seen that the power joint is). Therefore, when the motor A is driven, the rotational force of the motor A is transmitted to the measurement motor D through the torque detector C to rotate the core 30 inside the measurement motor D. At this time, the torque detector C measures the torque required to rotate the core 30 and displays the torque to the outside. Of course, when the force applied to the magnet facing surface of the core 30 is strong, the maximum and minimum values of the torque become large.

6A and 6B are graphs showing, as a reference, torque characteristics of a motor measured using the vibration detection device shown in FIG. FIG. 6A shows a torque characteristic of a motor in which a conventional general core (18 in FIG. 1) is embedded, and FIG. 6B captures a shape screen displaying the torque characteristic of a motor in which the core (30 in FIG. 3) of the present invention is embedded. Indicated. In particular, in the core used in the test, the sizes of the other portions except for the grooves 30d are the same.

In the graphs shown in Figs. 6A and 6B, the Y axis is torque and the X axis is time.

Referring to the drawings, it can be seen that irregular sinusoids are displayed in each graph. One cycle of the sinusoid represents the change in torque applied to the drive shaft 20 while the core is moved by one pitch as described above.

In addition, the maximum point in each cycle of the sinusoidal curve is that the rotation axis of the torque detector C rotates the drive shaft of the motor so that the magnet opposing surface 18y enters the inner region of the magnet as shown in FIG. The torque value at the moment, and the minimum value is the torque value at the moment when the magnet opposing surface 18y enters the inner region of the magnet. Since the entrance of the magnet opposing surface 18y after the maximum value is made only by the magnetic force of the magnet 16, the torque applied to the torque detector C becomes a negative value.

The difference between the maximum and minimum values of the torque is proportional to the magnitude of the vibration. For example, if there is no difference between the maximum value and the minimum value, there will be no vibration due to the rotation of the core. On the contrary, the larger the difference, the greater the vibration generated between the core and the magnet.

In any case, by forming a groove in the magnet opposing face as described above, by extending the average separation distance of the magnet opposing face with respect to the magnet, it was possible to reduce the difference between the maximum and minimum values of the torque to reduce the vibration generated from the motor. Applicant's test confirmed a vibration reduction effect of 20% or more.

In addition, since the inertia moment of the core 30 is reduced by forming the groove 30d, the inertia force at the moment when the core rotates and stops by one pitch becomes small, so that the minimum value of the torque is also reduced. In other words, the groove serves to reduce the weight of the core and at the same time reduce the vibration.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to the said Example, A various deformation | transformation is possible for a person with ordinary knowledge within the scope of the technical idea of this invention.

According to the present invention made as described above, by forming a groove of a predetermined shape on the magnet opposing surface of the rotor core, the vibration generated from the core when driving the motor is reduced as well as the weight is light, so that the power consumption can be reduced accordingly.

Claims (2)

In the core of the electric motor that is opposed to the magnet provided on the inner wall surface of the casing of the electric motor, the outer peripheral surface thereof has a magnet opposing surface divided by a plurality of core slots and rotates by electricity supplied from the outside, The core of the electric motor, characterized in that at least one groove is formed on the magnet opposing surface. The method of claim 1, The groove extends in a direction perpendicular to the direction of rotation of the core and has a predetermined width and depth of the core of the electric motor.

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