JP2004248443A - Dc brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC brushless motor which can be manufactured inexpensively and can be assembled easily in a short time. <P>SOLUTION: The rotor comprises a central shaft 1, and a rotor core 2 consisting of two rotor modules 2A and 2B being fitted, side by side in the axial direction, over the central shaft 1. The central shaft 1 is provided with a key groove 9 in parallel with the axial direction and each rotor module is provided with a key groove 8 in parallel with the axial direction while being shifted by a specified pitch angle in the order of the key grooves 8 being fitted over the central shaft 1. When a linear key 10 is fitted in the key groove 9 of the central shaft 1 and the key groove 8 of each rotor module while arranging the key grooves 8 in the axial direction, each rotor module is secured while being skewed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a DC brushless motor.
[0002]
[Prior art]
Conventionally, in a DC brushless motor, a permanent magnet supported by the rotor is twisted around the rotor axis in order to prevent the output torque from being rippled (torque ripple) due to cogging torque and generating noise and vibration. (Skewed).
[0003]
For example, while forming a keyway twisted on the outer peripheral surface of the center shaft, a keyway inclined with respect to the axial direction at a predetermined rotation phase is formed on the inner peripheral surface of the rotor module, and A technique has been proposed in which the key grooves of each rotor module are aligned, and keys are fitted into these key grooves to fix each rotor module, thereby providing equivalent skew (see the following document).
[0004]
[Patent Document 1]
JP-A-8-317882
[Problems to be solved by the invention]
However, according to the above-mentioned prior art, there is a problem that the key groove cannot be easily formed because it is a spiral groove, and a skill is required for assembling the rotor module and the center shaft.
[0006]
Therefore, an object of the present invention is to provide a DC brushless motor that can be manufactured at low cost and that can be easily and quickly assembled.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a DC brushless motor according to the present invention is directed to a DC brushless motor including a rotor including a central shaft and a plurality of rotor modules that are externally fitted to the central axis in an axial direction. A linear key groove parallel to the axial direction is formed in the outer peripheral portion of the rotor module, and the inner peripheral portion of each rotor module is deflected by a predetermined pitch angle in the order in which the key groove is fitted to the central axis. The key grooves of the respective rotor modules are aligned in the axial direction, and the linear keys are fitted into the key grooves of the central shaft and the key grooves of the respective rotor modules. Each rotor module is skewed and fixed by the pitch angle with respect to the center axis.
[0008]
Here, the number of rotor modules may be an even number of 2 or more or an odd number of 3 or more. Further, the pitch angle for biasing the key groove of each rotor module may be set to a value obtained by equally dividing the optimum skew angle p of the DC brushless motor by one less than the number of rotor modules used in the DC brushless motor. .
[0009]
According to the present invention, since the rotor can be divided in the axial direction and equivalently skewed, the cogging torque can be reduced to reduce torque ripple, and the cogging torque can be reduced to reduce noise and vibration. And the effect that the high frequency component of the induced voltage can be reduced.
[0010]
Further, according to the present invention, the key groove of the central axis used for fixing each rotor module with respect to the central axis and the key groove of each rotor module can be linearly parallel to the axial direction. Can be used, the key groove can be formed simply and inexpensively, and each rotor module can be easily and quickly assembled to the central shaft.
[0011]
By the way, in the present invention, since each rotor module is formed so as to be deviated by a predetermined pitch angle in the order in which the key grooves are fitted to the center axis, the same number of kinds of rotor modules as the number of rotor modules used in the DC brushless motor are used. Although a different rotor module may be used, the rotor module may be turned upside down so that it can be externally fitted to the center shaft, so that the number of necessary rotor modules may be reduced.
[0012]
That is, when the number of rotor modules is 2 m (m is an integer of 1 or more), the first to m-th rotor modules have a predetermined pitch angle ( For example, p / (2m-1)) is formed so as to be deviated, and the (m + 1) -th to (2m) -th rotor modules use the first to m-th rotor modules upside down. And the (m-1) th rotor module can be turned upside down to be the (m + 1) th rotor module, and the (m-1) th rotor module can be turned upside down to be the (m + 2) th one. . With this configuration, a DC brushless motor configured using 2m rotor modules can be configured with m types of different rotor modules, and the DC brushless motor can be manufactured at lower cost.
[0013]
When the number of rotor modules is 2m + 1 (m is an integer of 1 or more), the first to m + 1th rotor modules have a predetermined pitch angle (e.g., p / 2m), and the m + 2th to 2m + 1th rotor modules are used with the first to mth rotor modules upside down. That is, the mth rotor module is used upside down. Inversely, the (m + 2) -th module can be reversed, the (m−1) -th rotor module can be reversed, and the (m + 3) -th module can be reversed. In this way, a DC brushless motor configured using 2m + 1 rotor modules can be configured with m + 1 different types of rotor modules, and a DC brushless motor can be manufactured at lower cost.
[0014]
In the present invention, the structure in which each rotor module supports the permanent magnet and the shape of the permanent magnet are not particularly limited, and a known structure or a known shape may be adopted.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A DC brushless motor according to an embodiment of the present invention will be specifically described below with reference to the drawings.
[0016]
As shown in FIG. 1, the rotor of the DC brushless motor according to the first embodiment of the present invention includes a center shaft 1 and a rotor core 2, and the rotor core 2 includes two upper and lower rotor modules 2A and 2B.
[0017]
FIG. 2 is a perspective view of the rotor module 2A. As shown in FIG. 2, the rotor module 2A is arranged at a certain distance from the axis of the core 3 and is equiangular in the rotation direction, here 90 degrees. And four permanent magnets 4 mounted at four places at an angle.
[0018]
The core 3 is formed by laminating a predetermined number of core plates 5 in the axial direction. As shown in FIG. 3, the contour of each core plate 5 is formed in a circular shape, and the central axis 1 is inserted through the center thereof. A shaft insertion hole 7 is formed at the periphery of the shaft insertion hole 7 in a slit shape orthogonal to the radial direction at every 90 °. Each core plate 5 is formed with a pair of key grooves 8 for externally fitting the rotor module 2A to the central shaft 1.
[0019]
The key groove 8 is formed continuously with the shaft hole 6 at a position opposed to the axis of the core plate 5 with respect to the axis thereof, and is shifted circumferentially by a predetermined pitch angle p / 2 from a reference position indicated by a broken line in FIG. It is formed at a deviated position. Here, the reference position is set on a straight line C passing through the center point of the two permanent magnets 4 facing each other. The angle p is an optimum skew angle in the DC brushless motor, and is set in consideration of torque ripple, magnetic interference of a permanent magnet used in each rotor module, and the like.
[0020]
As shown in FIG. 2, the core 3 is formed by laminating a predetermined number of the same core plates 5 with the front and back directions aligned, so that the shaft hole 6, the magnet insertion hole 7, and the key groove 8 are all parallel to the axial direction. It will be formed in a shape penetrating linearly. The permanent magnet 4 is formed in the shape of a rectangular flat plate, and is inserted into each of the magnet insertion holes 7 that are stacked and communicated as shown in FIG.
[0021]
The rotor module 2B has exactly the same configuration as the rotor module 2A. As shown in FIG. 1, the upper and lower rotor modules 2A and 2B are turned upside down with respect to each other so that the center axis is aligned with the key groove 8 aligned. 1 outside. Here, since the key groove 8 is formed at a position deviated in the circumferential direction by a predetermined pitch angle p / 2 from the reference position, the key groove is formed by turning the rotor module 2A upside down with the rotor module 2B. 8 are deflected by an angle p which is twice the pitch angle p / 2 in the order in which the rotor modules 8 are externally fitted to the center shaft 1. By fitting the key grooves 8 of the respective rotor modules and externally fitting them, the rotor module is It is skewed by the angle p in the circumferential direction. Note that the angle p that is deviated in the order in which the key grooves 8 are fitted to the center shaft 1 as described above is equal to the skew angle p, and the skew angle p is one less than the number of rotor modules (2), that is, one. It is something that is divided.
[0022]
On the other hand, on the outer peripheral surface of the center shaft 1, two key grooves 9 are formed in the axial direction, and a common linear key 10 is engaged in the key grooves 9 and the key grooves 8 of both rotor modules 2A, 2B. This prevents the two rotor modules 2A, 2B from rotating relative to the center axis 1.
[0023]
In this embodiment, the upper and lower rotor supports 11 are externally fitted to the central axis with the upper and lower rotor modules 2A and 2B interposed therebetween, and these rotor supports 11 are supported on the central axis 1 so as to be unable to advance and retreat in the axial direction. The position of the upper and lower rotor modules 2A, 2B in the axial direction with respect to the central axis 1 is regulated.
[0024]
Now, according to this embodiment, the rotor 2 can be divided into two parts in the axial direction and equivalently skewed, whereby the cogging torque can be reduced and the torque ripple can be reduced. To reduce noise and vibration, and to reduce the high frequency component of the induced voltage.
[0025]
Further, according to this embodiment, since the same rotor modules 2A and 2B are arranged upside down, only one kind of the rotor module and the core plate is required, thereby reducing the manufacturing cost by mass production of a small number of kinds. At the same time, it is not necessary to pay attention to the order of lamination of the core plates 5 during lamination, and the rotor module can be easily assembled in a short time. Further, according to this embodiment, the key groove 9 formed in the center shaft 1 is formed linearly, and the linear key 10 is engaged with the key groove 9 and the key groove 8 of each rotor module 2A, 2B. Therefore, the key grooves can be formed more easily and inexpensively than when a spiral key groove is formed on the central shaft 1, and each rotor module 2A, 2B can be easily and quickly connected to the central shaft 1. Can be assembled.
[0026]
FIG. 4 is an exploded perspective view of a rotor of a DC brushless motor according to another embodiment of the present invention. The rotor of this embodiment includes upper and lower three rotor modules 2A, 2E, and 2B. The rotor modules 2A and 2B at both the upper and lower ends are configured in the same manner as in the above embodiment except for the axial dimension (the rotor module 2A and the rotor module 2B have the same configuration and are used upside down with respect to each other). The keyway 8 is formed at a position deviated in the circumferential direction by a predetermined pitch angle p / 2 from the reference position. The central rotor module 2E has a key groove 8 formed at the reference position of the core 3, and the other configuration is the same as the rotor modules 2A and 2B according to this embodiment.
[0027]
The rotor modules 2A, 2B are arranged upside down with respect to each other, and the rotor module 2E is arranged therebetween. The key grooves 8 of the three rotor modules 2A, 2E, 2B are aligned. The linear key 10 is fitted into the key shaft 9 and the key groove 9 formed on the central shaft 1, thereby being fixed to the central shaft 1.
[0028]
Here, the key grooves 8 of the rotor modules 2A, 2B are formed at positions offset from the reference position by a predetermined pitch angle p / 2 in the circumferential direction. It is deviated by a pitch angle of p / 2 in the order of external fitting. That is, the key groove 8 of the rotor module 2A is deviated from the key groove 8 of the rotor module 2E by the pitch angle p / 2, and the key groove 8 of the rotor module 2B is pitched by the pitch angle p with respect to the key groove 8 of the rotor module 2E. / 2, and the keyway 8 of the rotor module 2A is offset from the keyway 8 of the rotor module 2B by an angle p that is twice the pitch angle p / 2. Then, by fitting the key grooves 8 of the respective rotor modules to each other and fitting them outside, the respective rotor modules are skewed by the pitch angle p / 2 in the circumferential direction, and the entire rotor is skewed by the angle p. become. Note that the angle p / 2 at which the keyway 8 is deviated in the order in which the keyway 8 is externally fitted to the central shaft 1 as described above is a value obtained by dividing the skew angle p by one less than the number of rotor modules (3), that is, by two. Have been.
[0029]
According to this embodiment, the rotor 2 can be divided into three parts in the axial direction and equivalently skewed, whereby the cogging torque can be reduced and the torque ripple can be reduced, and the cogging torque can be reduced. As a result, an effect that noise and vibration can be reduced, an effect that a high-frequency component of an induced voltage can be reduced, and the like can be obtained.
[0030]
Further, according to this embodiment, there can be two types of rotor modules constituting the three-tiered rotor 2, and since each rotor module is composed of one type of core plate, the rotor module and A relatively small number of types of core plates is required, so that the cost can be reduced by mass production of a small number of types, and the effect that the assembly can be easily performed in a short time can be obtained.
[0031]
【The invention's effect】
As described above, according to the present invention, the rotor can be divided in the axial direction and equivalently skewed, whereby the cogging torque can be reduced and the torque ripple can be reduced. The effect that noise and vibration can be reduced by reducing the cogging torque, the effect that the high frequency component of the induced voltage can be reduced, and the like can be obtained.
[0032]
Further, according to the present invention, since the rotor module can be fixed to the central axis using the linear key, the key groove can be formed easily and inexpensively, and the key can be formed at low cost. And the effect that each rotor module can be easily attached to the center axis in a short time.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of the present invention.
FIG. 2 is a perspective view of the present invention.
FIG. 3 is a plan view of the present invention.
FIG. 4 is an exploded perspective view of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Center axis 2 Rotor core 2A Rotor module 2B Rotor module 2E Rotor module 4 Permanent magnet 5 Core plate 6 Shaft hole 8 Keyway 9 Keyway 10 Straight key p Skew angle

Claims (2)

In a DC brushless motor including a central shaft and a rotor including a plurality of rotor modules that are externally arranged side by side in the axial direction on the central shaft,
A linear keyway parallel to the axial direction is recessed on the outer periphery of the center shaft, and a predetermined pitch angle is formed on the inner periphery of each rotor module in the order in which the keyways are fitted to the center shaft. Are deviated one by one, and penetrate in parallel to the axial direction,
The key grooves of each rotor module are aligned in the axial direction, and the linear keys are fitted into the key grooves of the central axis and the key grooves of the rotor modules, whereby each rotor module is skewed by the pitch angle with respect to the central axis. DC brushless motor characterized by being fixed. The DC according to claim 1, wherein the pitch angle is set to a value obtained by equally dividing an optimum skew angle of the DC brushless motor by one less than the number of rotor modules used in the DC brushless motor. Brushless motor.

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