JPH04207949A - Motor - Google Patents

Abstract

PURPOSE:To make it possible to conduct an accurate relative positioning of a magnetic pole and a brush just by pushing a baseplate into a housing by installing a positioning piece which fits in a recessed part of an uneven part of the magnetic pole on the baseplate on which the brush is mounted. CONSTITUTION:As shown by the figure, a magnetic pole 1 has a flat part 1A on one end and an uneven part 1B on the other end. On a baseplate 8, a brush 10 is mounted which gets brought into contact with a bearing 9 and a commutator 7. A positioning piece 11 has a square-shaped cross section and is so installed on the inner face of the baseplate that a protruding part faces inwards. For positioning, the positioning piece 11 gets fit on the boundary part 1B' between the N pole and S pole in the uneven part 1B of the magnetic pole 1. Because the positioning piece 11 which fits in the recessed part of the uneven part of the magnetic pole 1 is mounted on the baseplate 8, a relative positioning of the brush and the magnetic pole is conducted automatically just by pushing the baseplate into a housing 2' so that the positioning piece may fit in the recessed part. Consequently, assembly can be done very easily.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention aims to improve the efficiency of assembly work in a motor with improved torque characteristics by devising the shape of a permanent magnet.

[Prior Art] Three-phase small motors are used in home appliances, office automation equipment, automobile parts, and the like. With the miniaturization of equipment, there has been a demand for reduction in torque ripple in these motors as well.

Figure 3 shows a motor with two pole magnets, three salient poles, and a delta connection, and the current quantity is also a general-purpose motor.

In this figure, 1 is a magnetic pole made of a ring-shaped permanent magnet, and N
i and S&, and is fixed to a housing 2 which also serves as a magnetic yoke. 3 is the armature, salient pole 4 and coil 5
are arranged opposite to the magnetic pole 1 with a gap g. Reference numeral 6 denotes a rotating shaft, which is supported together with the armature 3 and the magnetic pole 1 by a support member (not shown).

When assembling these motors, please refer to Figures 4(a) and (
A ring-shaped magnetic pole 1 as shown in FIG. 5 or a magnet 11 consisting of two C-shaped permanent magnets 1a and 1b is attached to the housing 2 in an unmagnetized state, and then the magnetic pole 1 as shown in FIG. Magnetic device 20 is sandwiched between magnetic poles 21 and 21, and magnetization is performed by passing a large current through winding 22, and magnetization is performed while attached to housing 2.

Figure 2 shows a magnet shape 1 of a motor that hardly causes torque ripple, which the inventor proposed in Japanese Patent Application No. 1-187252.
This is an example of a flat development of & minutes.

The principle of this motor will be explained below.

The torque TQ of the radial gap type motor is shown in (2) below.
It is given by Eq.

Here, F, (θ): Amount of magnetic flux in the radial direction in gear g. Fe (θ): Amount of magnetic flux in the rotational direction in gear g. R:
The radius ν at the position of the gap g. : Magnetic resistivity in gear g.

The simplest motor with two magnetic poles shown in Fig. 3 mentioned above,
This will be explained using a three salient pole motor as an example. ψ is the angle of one salient pole, θ
. Let be the angle of the end of a certain salient pole from the reference position. As shown in equation (2), the torque TQ is F, (θ)・F
o (θ), so it can be considered that it occurs only in the gear g between the salient pole 4 with a large magnetic flux density and the magnetic pole 1 made of a permanent magnet, and the integral of equation (2) is the product of the salient pole 4. Only a certain part is enough.

Let the radial direction magnetic flux amount F, (θ) be the magnetic flux distribution generated by the magnetic pole 1 in the radial direction, and the magnetic flux distribution generated by the magnetic fi1 is expressed as a composite value of the fundamental wave and harmonics of the sine wave. N
, one pair of S poles is 2π and one period T, so 2πnθ/2
By expressing π=nθ, it can be expressed by the following equation.

rr(θ)=F0(sinθ+Σβ,・sin nθ
)g2... (3) However, Fo is a constant. In addition, F by a permanent magnet,
In the distribution formula of (θ), n is 2.3°4,...
β is an integer of . represents the mixing ratio of the n-order component to the first-order component. In formula (3), β. = (b
n/b+) and FO=b, the form matches the expression in equation (1) when the constant ri and cosine component are zero. That is, in this invention, it is considered that the amount of magnetic flux F(θ) has the following relationship with the distance ah<θ) in the width direction of the permanent magnet.

Since the magnetic flux Fe (θ) in the rotational direction is given by the differential of Fr (θ) in the rotational direction, =-Fo(cosθ+Σ β, + n CO5nθ)
...... (4) It becomes. In terms of F and (θ)・Fe (θ) in equation (2), if we focus on the fundamental wave and one specific n component, we find that = −Fo” [−5ln2 f3 + ! (sin
(n+1)θ1.

-sin(n-1) e)+'--(sin(n-1)
θ)+sin (n-1) θ+ βn” sin
nθ1CO8nθ]... (5) Ratio β of the n-order component to the fundamental wave. is usually small and βn′(
1, the last term can be ignored.

Next, when the magnetic flux component F generated by the magnetic field 8i1 is only the order component of (θ), the term Fr(θ)・F(θ) in equation (2) is k.

Fr(θ)4e (θ)=-F, θ in 2--sin2
...... (6) becomes.

Cogging torque is calculated when magnetic pole 1 has a magnetic flux distribution of a single high-order sine wave, except when the order is an integral multiple of the salient pole (3, 6, 9, etc. in the case of this motor). Since it is zero, cogging torque occurs when n±1 becomes an integer multiple of 3 in equation (5). Part (5), (6
), it is clear that n±1 and 2k correspond.

That is, in this motor, cogging torque occurs when the fundamental wave includes a component such that (n±1)/2 is a multiple of 3 among the harmonic magnetic flux components of the first mode. For example, n=
In the case of 5, cogging torque does not occur in the 5th mode alone, but when the 5th mode is slightly added to the fundamental mode, (5 + 1) / 2 = 3, and the cogging torque is generated by a single 3rd order translated wave magnetic flux component. A torque pattern occurs. vice versa,
Even if the mode generates cogging torque by itself, if it is combined with the fundamental wave, β in equation (5). It only affects the term ′, and rather cogging torque does not occur much. In other words, when a higher-order mode is mixed with the fundamental wave, a cogging torque pattern of the higher-order mode alone is not generated, but acts nonlinearly.

In order to reduce the cogging torque in this way, it is necessary to correct the shape of the magnetic pole 1 in the width direction as shown in equation (1). That is, in order to precisely control the magnetic flux distribution generated in the field section, the permanent magnets constituting the magnet 8ii have a special shape, but it is also necessary to accurately distribute the magnetization. Therefore, in this type of motor, it is usually necessary to precisely magnetize a single permanent magnet and then attach the permanent magnet to the housing 2, and setting the permanent magnet to an accurate position on the housing 2 is time-consuming. Such was the work. This invention has such a special shape, that is, one end side of the permanent magnet of the field part has an uneven shape.

To provide a motor which can smoothly attach a normally magnetized magnet to an accurate position in a housing 2 by utilizing the special shape of the magnet.

[Means for Solving the Problems] The motor according to the present invention has a permanent magnet that is flat at one end and has an uneven shape at the other end to control higher-order components of magnetization to correct torque ripple. An armature that includes a field part as a magnetic pole, a salient pole facing the field part, a winding attached to the salient pole and a shaft passing through the salient pole, and a front north field part. , and includes a housing including a bearing that supports one end of the shaft of the salient pole, a bearing that supports the other end of the shaft, and a brush for the salient pole, and engages with the uneven shape of the field part, It consists of a bottom plate equipped with a positioning piece that determines the relative position with the field part.

[Effect]

In this invention, after inserting a magnetized permanent magnet into the housing at an approximate position, the permanent magnet is rotated relative to the housing by inserting a bottom plate having a positioning piece on the inner side that engages with the recess of the permanent magnet. , the positional relationship between the permanent magnet and the brush can be determined accurately.

(Embodiment) FIG. 1 is an exploded perspective view of an embodiment of the present invention before assembly. In this figure, the same reference numerals as in FIG. 3 indicate the same parts. For example, in equation (1), the magnetic pole 1 is b5=
0. The permanent magnet represented by I X'H0,b7 =0.05×Ho has one end 1A flat and the other end uneven 1B as shown in FIG. A commutator 7 is provided on the rotating shaft 6 of the salient pole 4 .

Reference numeral 8 denotes a bottom plate, which includes a brush 1 that contacts the bearing 9 and the commutator 7.
0 is set. ] 1 is a positioning piece, for example, the cross section is 3
It has a rectangular shape and is provided on the inner surface of the bottom plate 8 so that the protrusion faces inward, and engages with the boundary part IB' between the N& and S poles of the unevenness 1B of the 6i[il for positioning. Thereby, relative positioning of the brush 10 and the magnetic pole 1 is performed. 12 is a bearing provided in the housing 2.

Next, assembly will be explained with reference to FIG.

The magnetic pole 1 is inserted into the housing 2, and then the rotating shaft 6 of the salient pole 4 is inserted into the bearing 12 of the housing 2. Then,
While passing the rotating shaft 6 through the bearing 9 of the bottom plate 8, insert the positioning piece 11.
When the bottom plate 8 is pushed into the boundary portion 1B', the positioning piece 11 and the recessed portion of the boundary portion 1B' are engaged with each other, and the positioning piece 11 is automatically positioned.

[Effects of the Invention] As explained above, the present invention provides a motor consisting of a permanent magnet that is flat on one end and has an uneven shape on the other end in the axial direction for correction of lubrication and sobble. In,
Since a positioning piece that locks into the uneven recess is provided on the bottom plate to which the brush is attached, when assembling the brush and the field part, just push the positioning piece into the bottom plate housing so that it engages with the recess. Since the relative positioning is done self-help, there is an advantage that assembly is extremely easy.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of various parts showing an embodiment of the present invention.
FIG. 2 is a developed plan view showing an example of the north pole of the permanent magnet used in the present invention, and FIG. 3 is a schematic cross-sectional view of a conventional motor.
FIGS. 4(a) and 4(b) are perspective views showing the shape of a conventional permanent magnet with magnetic poles, and FIG. 5 is a schematic perspective view showing a conventional magnetizing device for a field section. In the figure, 1 is 1if1 pole, 2 is housing, 3 is armature, 4 is salient pole, 5 is coil, 6 is rotating shaft, 7 is commutator, 8 is bottom plate, 9 is bearing, 10 is brush, 11 is positioning Part 2 is η'+h. L and -, + Ni - (N ("") ka LI-1 ■ Figure 2 Figure 3 Figure 4 (a) (b)

Claims (1)

[Claims] A field section whose magnetic poles are permanent magnets that are flat on one end in the axial direction and have an uneven shape on the other end to control higher-order components of magnetization for correction of torque ripple. an armature comprising a salient pole facing the field part, a winding applied to the salient pole and a shaft penetrating the salient pole; a housing including a bearing that supports one end of the shaft; a bearing that supports the other end of the shaft; and a brush for the salient pole; A motor comprising: a bottom plate having a positioning piece that determines a relative position with a field part;