The rotor of brushless DC motor
Technical field
The present invention relates to the rotor of motor such as brushless DC motor (Block ラ シ レ ス DC モ one タ), single-phase synchronous motor.
Background technology
The rotor of motor such as brushless DC motor is in order to obtain the form (reference example such as patent documentation 1) that magnetic force becomes the S utmost point and the N utmost point to replace configurations of magnets.
In such rotor, the rotor of the SPM type (SURFACE PERMANENT MAGNET type) at the surface configuration magnet of rotor core is arranged.
Patent documentation 1: TOHKEMY 2004-48827 communique
The employed magnet of the rotor of SPM type as described above, mostly being ferrite is plastic magnet, interior external diameter is concentric annular, and is integrally formed or constitute ordinatedly with rotor core.And,, the field orientation of each diversity of magnetic pole is set at each predetermined angular.
In such toroidal magnet, irrespectively more weak at the boundary member of the S utmost point and the N utmost point with the power of orientation, use with the center of each magnet, be the magnet of the center same amount of magnetic pole.
When the magnet that uses in this wise with the center same amount of magnetic pole, exist the amount of plastic magnet to increase, the problem that cost improves.
In addition,, when more weak, exist only rotor core to rotate to the cooperation of rotor core owing to be the magnet of annular, or the problem of toroidal magnet rotation only.
Summary of the invention
The present invention provides the rotor of the brushless DC motor that a kind of amount that can reduce plastic magnet and magnet do not rotate relative to rotor core in view of the above problems.
The invention of technical scheme 1, be with the rotor outer circumferential side be magnetized to S extremely in all sides be magnetized to the plastic magnet of the N utmost point and described rotor outer circumferential side be magnetized to N extremely in all sides plastic magnet one utmost point one utmost point of being magnetized to the S utmost point alternately be arranged on the rotor of the brushless DC motor on the outer peripheral face of rotor core, wherein, to be formed for the axis hole of axle at the central part of described rotor core and form a plurality of semicircular recesses in the mode of five equilibrium configuration and to constitute the steel plate of star stacked at peripheral part, the section configuration of interior all sides of the plastic magnet of described each utmost point has formed semicircular a plurality of protuberances that central portion is swelled, the plastic magnet of described each utmost point forms as one ringwise, and described plastic magnet and described rotor core are integrally formed.
In the present invention, the section configuration of interior all sides of the plastic magnet of described each utmost point is for roughly semicircle.
In the present invention, the plastic magnet of described each utmost point and described rotor core are integrally formed.
In the present invention, described rotor core is a cydariform, axially has a curvilinear recess at its peripheral part.
In the present invention, described motor is a brushless DC motor.
In the present invention, described motor is a single-phase synchronous motor.
In the rotor of the motor of the invention of claim 1, though plastic magnet is an annular, but the section configuration of interior all sides of the plastic magnet of each utmost point is the curve form that makes central portion swell, become thin more by the end more, so compare the amount of use with the annular plastics magnet of prior art few, in addition, the magnetization waveform of magnetic flux is near sinusoidal wave, and the characteristic of motor improves, and then, the situation of rotating relative to rotor core can not appear.
According to the present invention because the section configuration of the plastic magnet of each utmost point is for roughly semicircle, so the magnetization waveform of magnetic flux near sinusoidal wave, the characteristic raising of motor.
According to the present invention,, can more positively cooperate with rotor core plastic magnet because the plastic magnet and the rotor core of each utmost point are integrally formed, easy to manufacture.
According to the present invention, because rotor core is cydariform, so the plastic magnet relative stator iron core that each utmost point can not occur coming off in the axial direction.
According to the present invention,, can improve the characteristic of motor because motor is a brushless DC motor.
According to the present invention,, can improve the characteristic of motor because motor is a single-phase synchronous motor.
Description of drawings
Fig. 1 is the figure of the flat shape of the rotor of expression the present invention one example.
Fig. 2 is the A-A line sectional view of Fig. 1.
Embodiment
Below, with reference to Fig. 1 and Fig. 2 the rotor 10 of the present invention's one example is described.
The rotor 10 of this example is the rotor of brushless DC motor, is configured in interior all sides of annular stator.
The structure of rotor 10
Structure and its manufacture method to rotor 10 together describe.
At first, make the rotor core 12 of rotor 10.
As shown in Figure 1, the flat shape of rotor core 12, by the star steel plate that the peripheral part in circle is provided with 8 semicircular recesses 14 carry out stacked, the riveted joint make.At this moment, as shown in Figure 2, for forming the such shape of recess, global shape is a cydariform to the axial shape of rotor core 12 at axial central portion.
Then, the above-mentioned rotor core that makes like that 12 is received into metal die inside, the ferrite that is formed with each utmost point at the peripheral part of rotor core 12 integratedly is a plastic magnet 16.In addition, make axle 18 as rotation axis connect centers in rotor core 12.At this moment, as shown in Figure 1, the plastic magnet 16 of each utmost point is the annular that links with the end, and shape of all sides and recess 14 is coincide in it, and section configuration is the curve form that central portion swells, becomes thin more by the end more, and is promptly roughly semicircle.It is the circular concentric at center that the section configuration of the outer circumferential side of the plastic magnet 16 of each utmost point becomes with axle 18.
The interior perimembranous of metal die is magnetized or is disposed permanent magnet, makes the plastic magnet 16 of each utmost point alternately be magnetized to the S utmost point and the N utmost point.
The above-mentioned rotor 10 that is shaped is integratedly like that taken out from metal die.
The effect of rotor 10
Above-mentioned rotor 10 has following such effect.
As the 1st effect, to compare with the situation of the annular plastics magnet that uses prior art, the use amount of the plastic magnet 16 of each utmost point reduces, can cutting down cost.Promptly, as shown in Figure 1, if the words of the annular plastics magnet of the circular concentric of prior art, be necessary to use plastic magnet until the position shown in the dotted line 20, but at this example because plastic magnet 16 is configured to the shaped form of coincideing with recess 14, so can reduce the use amount of the so much plastic magnet 16 of the use amount that is equivalent to Fig. 1 intermediate cam shape than prior art.
As the 2nd effect, owing at the peripheral part of rotor core 12 recess 14 is set, the shape of plastic magnet 16 for being mated can not rotated relative to rotor core 12 so connect into the plastic magnet 16 of annular.That is, play the effect of this recess 14 of stop.
As the 3rd effect, because rotor core 12 be cydariform, so can prevent the disengaging of plastic magnet 16 on Fig. 2 axial.
As the 4th effect and since interior all sides of the plastic magnet 16 of each utmost point be shaped as semicircle, so the magnetization waveform of magnetic flux near sinusoidal wave, the characteristic of motor improves.
(modified example)
The invention is not restricted to above-mentioned example, only otherwise breaking away from its purport can carry out various changes.
Modified example 1
Is integrally formed at above-mentioned example rotor unshakable in one's determination 12 with plastic magnet 16, but also can not be shaped like this, can be the manufacturing process that is inserted into the blank part at its center after the plastic magnet 16 that formerly only is shaped, with rotor core 12.
Modified example 2
In above-mentioned example, used brushless DC motor, but also be not limited thereto,, for example, also can be used in the rotor of single-phase synchronous motor if rotor uses the words of permanent magnet also can be suitable for the present invention as motor.
Industrial applicibility
The present invention is applicable to the rotor of brushless direct current motor, single-phase synchronous motor etc.