JP3624321B2 - Electric motor rotor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electric motor rotor.
[0002]
[Prior art]
In recent years, an electric motor used for home appliances such as an air conditioner or a washing machine is required to be an electric motor with less vibration and noise. Therefore, various methods have been taken to prevent vibrations generated from the electric motor. A conventional electric motor using a rotor for attenuating transmission of vibration will be described with reference to FIGS. 4 to 8 using a brushless DC motor as an example. FIG. 4 is a perspective view of the rotor of the first conventional example. FIG. 5 is a BB cross-sectional view of the rotor in FIG. FIG. 6 is a perspective view of a rotor of a second conventional example. 7 is a cross-sectional view of the rotor in FIG. 6 taken along the line CC. FIG. 8 is a side sectional view of a brushless DC motor using the rotor of the first conventional example.
[0003]
4 and 5, the rotor 35 is formed by laminating donut-shaped iron plates, and a rotor core 36 formed in a cylindrical shape, and a cylindrical rubber 37 fixed to the inner periphery of the rotor core 36. And a shaft 38 fixed to the inner periphery of the rubber 37 and a magnet 39 fixed to the outer periphery of the rotor core 36.
[0004]
6 and 7, the first rotor core 40a is formed in a cylindrical shape by stacking donut-shaped iron plates. The second rotor core 40b is formed in a cylindrical shape by stacking donut-shaped iron plates. The diameter of the outer periphery of the second rotor core 40b is smaller than the diameter of the inner periphery of the first rotor core 40a, so that the first rotor core 40a and the second rotor core 40b are made. When arranged on the same axis, a gap is provided between the inner periphery of the first rotor core 40a and the outer periphery of the second rotor core 40b. A cylindrical rubber 42 is inserted into the gap, and the first rotor core 40a and the second rotor core 40b are fixed by the rubber 42. Then, the shaft 43 is fixed to the inner periphery of the second rotor core 40b. And the magnet 44 is fixed to the outer periphery of the first rotor core 40a. The rotor 41 is configured as described above.
[0005]
In FIG. 8, the brushless DC motor 55 includes a frame 57 in which the stator 50 is molded by a premix 56 and a rotor 35 attached to the inside of the frame 57.
[0006]
When electric power is supplied to the brushless DC motor described above, a rotational torque with a constant force for rotating the rotor is generated in the gap between the surfaces where the stator and the rotor face each other. This rotational torque is transmitted to the load via the rotor core and the shaft.
[0007]
In addition, since this brushless DC motor uses a transistor in the drive circuit, it is caused by the switching noise of the transistor generated when switching the current flowing through each winding, and by the deviation of the magnetization pitch when magnetizing the magnet. A vibration torque is generated in which the direction of the force changes with time. This vibration torque generates vibration and is combined with the rotational torque described above, and is transmitted to the load, for example, a fan, etc. via the rotor core and shaft, and to the mounting plate etc. via the stator. It is divided into transmission paths, each of which generates noise due to resonance and the like.
[0008]
Therefore, the first conventional example and the second conventional example are intended to prevent vibration transmitted through the rotor core and the shaft. In other words, by inserting rubber between the inner circumference of the rotor core and the outer circumference of the shaft fixed to this inner circumference, and by inserting rubber inside the rotor core, vibration is absorbed by the rubber. Thus, vibration can be prevented.
[0009]
[Problems to be solved by the invention]
However, in the rotors of the first conventional example and the second conventional example, rubber is provided between the rotor iron core and the shaft or between the rotor iron cores. Due to the deterioration of the rotor core, the rotor core may be greatly decentered, becoming unbalanced, and conversely promoting vibration. Further, there is no gap between the rotor and the stator facing the rotor, and the rotor and the stator come into contact with each other, causing a problem that the rotor is locked.
[0010]
[Means for Solving the Problems]
According to the present invention, in the rotor of the electric motor, the rotating body having a hole penetrating the central portion, the shaft inserted into the hole of the rotating body, the bearing inserted into the shaft, and the rotating body side of the bearing A washer disposed on a side surface; a spring washer disposed between the rotating body and the bearing; and a washer fixing device disposed at an arbitrary position of the shaft. By making it larger than the outer periphery of the shaft, a slight gap is provided between the inner peripheral surface of the rotating body and the outer peripheral surface of the shaft facing the inner peripheral surface, and this clearance minimizes the eccentricity of the rotating body with respect to the shaft. And a gap is formed in which the rotating body can move slightly in the circumferential direction and the rotating body can move freely in the axial direction, and between the bearing and the end face of the rotating body via the washer The spli By pressing the Guwassha, it provides rotor of the electric motor, characterized in that holding the rotating body to the shaft.
[0011]
[Action]
When electric power is supplied to the motor, the direction of the force for rotating the rotor in a predetermined direction on the rotating body is constant, and the torque of the force is almost constant, as well as the switching noise of the transistor described above, etc. As a result, vibration torque is generated in which the direction of the force changes with time.
[0012]
The rotational torque and vibration torque are transmitted from the rotating body to the load via the shaft.
[0013]
At that time, since the rotational torque is constant, when the rotating body rotates in an arbitrary direction, a part of the inner peripheral surface of the rotating body comes into contact with a part of the outer peripheral surface of the shaft and the shaft from the rotating body. Rotational torque is transmitted to. On the other hand, since the direction of the force of vibration torque changes with time, when the rotating body rotates in a direction opposite to the rotating direction in which the rotating torque is transmitted, the rotating body and the shaft are not in contact with each other and do not transmit the vibration torque. Therefore, only rotational torque is transmitted from the shaft to the load.
[0014]
【Example】
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a partial cross-sectional view of a rotor according to the present invention. FIG. 2 is a cross-sectional view of the AA portion of the rotor in FIG. FIG. 3 is a side sectional view of a brushless DC motor using the rotor according to the present invention.
[0015]
1 and 2, the rotating body 1 includes a rotor core 2 formed in a cylindrical shape by stacking donut-shaped iron plates, and a magnet 3 fixed to the outer periphery of the rotor core 2. ing. A hole 2a at the center of the rotor core 2 is formed in a D shape. The shaft 3 is formed such that the outer diameters at both ends are smaller than the outer diameter at the center, and the stepped portions 4a and 4b are formed at the boundary between the both ends and the center, respectively. The central portion of the shaft 3 is formed in a D shape so as to correspond to the hole 2 a of the rotor core 2.
[0016]
Then, the shaft 4 is inserted into the hole 2 a of the rotor core 2, and the rotating body 1 is temporarily fixed to the central portion of the shaft 4. Further, by making the inner diameter of the rotor core 2 larger than the outer diameter of the shaft 5, a slight gap S is provided between the inner peripheral surface of the rotor core 2 and the outer peripheral surface of the shaft 5 facing the inner peripheral surface. . The clearance S is such that the eccentricity of the rotating body 1 with respect to the shaft 4 can be minimized, the rotating body 1 can move slightly in the circumferential direction, and the rotating body 1 is free in the axial direction. Leave enough clearance to move to Then, spring washers 6a and 6b are inserted from both ends of the shaft 4, respectively. Then, by inserting the bearings 7a and 7b from the both ends of the shaft 4 to the stepped portions 4a and 4b, the spring washers 6a and 6b are pressed between the bearings 7a and 7b and both end surfaces of the rotating body 1, respectively. To. A retaining ring or the like may be used as a washer fixing device instead of the bearing. And the rotary body 1 is fixed between the spring washers 6a and 6b. The rotor 5 is configured as described above.
[0017]
In FIG. 3, the brushless DC motor 10 includes a frame 13 in which a stator 11 is molded by a premix 12 and a rotor 5 attached to the inside of the frame 13.
[0018]
When electric power is supplied to the brushless DC motor 10 described above, the direction of the force for rotating the rotor 5 in a predetermined direction on the rotating body 1 is constant, along with the rotational torque at which the magnitude of the force is substantially constant, Due to the switching noise of the transistors described above, vibration torque is generated in which the direction of force changes with the direction of rotation with time. The rotational torque and vibration torque are transmitted from the rotating body 1 to the load via the shaft 4.
[0019]
At that time, since the rotational torque is constant, when the rotating body 1 rotates in an arbitrary direction, a part of the inner peripheral surface of the rotor core 2 contacts a part of the outer peripheral surface of the shaft, Rotational torque is transmitted from the rotating body 1 to the shaft 4. On the other hand, since the direction of the force of vibration torque changes with time, when the rotating body 1 rotates in a direction opposite to the rotating direction in which the rotating torque is transmitted, the rotating body 1 and the shaft 4 are in a non-contact state, and the vibration torque Do not communicate. Therefore, only rotational torque is transmitted from the shaft 4 to the load. Furthermore, even when axial vibration due to magnet skew or the like occurs, the vibration can be attenuated by the spring washers 6a and 6b and transmitted to the load. Further, the rotating body may be fixed by arranging a spring washer only on one end face of the rotor core and using a retaining ring or the like on the other end face.
[0020]
Further, the shape of the hole 2a of the rotor core 2 and the central portion of the shaft 4 may be a polygonal shape or a keyhole shape in addition to the D shape. That is, there is a degree of freedom that allows slight movement in the circumferential direction, and rotational torque can be transmitted to the shaft 4 when the rotating body 1 rotates.
[0021]
In the present embodiment, the brushless DC motor has been described, but the same effect can be obtained also in other electric motors in which vibration torque is generated in the gap between the rotor and the stator facing the rotor.
[0022]
【The invention's effect】
According to the present invention, the vibration transmitted to the load can be attenuated without causing the rotor core to be eccentric, and noise due to resonance can be reduced.
[Brief description of the drawings]
FIG. 1 is a front view of a rotor according to the present invention as viewed from an axial direction.
2 is a cross-sectional view of the AA portion of the rotor in FIG. 1. FIG.
FIG. 3 is a side sectional view of a brushless DC motor using a rotor according to the present invention.
FIG. 4 is a perspective view of a first conventional rotor.
5 is a cross-sectional view taken along the line BB of the rotor in FIG. 4;
FIG. 6 is a perspective view of a rotor of a second conventional example.
7 is a cross-sectional view taken along the line CC of FIG.
FIG. 8 is a side sectional view of a brushless DC motor using a rotor of a first conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotating body 2, 36 ... Rotor core 3, 39, 44 ... Magnet 4, 38, 43 ... Shaft 5, 35, 41 ... Rotor 6a, 6b ... Spring Washers 7a, 7b ... bearings 10, 55 ... brushless DC motors 11, 50 ... stators 12, 56 ... premixes 13, 57 ... frames 37, 42 ... rubber

Claims (1)

In the rotor of the motor,
A rotating body having a hole penetrating through the central portion;
A shaft inserted into the hole of the rotating body;
A bearing inserted into the shaft;
A washer disposed on the side of the bearing on the rotating body;
A spring washer disposed between the rotating body and the bearing,
A washer fixing device disposed at an arbitrary position of the shaft,
By making the hole of the rotating body larger than the outer periphery of the shaft, a slight gap is provided between the inner peripheral surface of the rotating body and the outer peripheral surface of the shaft opposite to the inner peripheral surface. The bearing is configured to form a gap in which the rotating body can move slightly in the circumferential direction and the rotating body can freely move in the axial direction, and the washer is interposed therebetween. A rotor of an electric motor, wherein the rotor is held on the shaft by pressing the spring washer with an end face of the rotor.

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