JPH06113496A - Rotating magnetic-field generating coil in electromagnetic rotating machine - Google Patents

Abstract

PURPOSE:To make it possible to design an optimum motor with large starting torque and maximum on-load torque, and low consumption, by winding a coil in a contrived way with respect to a rotating field generating coil for a small motor like a spindle motor in a small and thin shape. CONSTITUTION:When a former 3 is moved forward and backward to turn a wire around projected poles 201 to 203 at a motor core, at least one adjoining upper layer having a smaller number of turns than that of a lower layer is formed, and the upper layer is provided in a place just off the center of the projected poles 201 to 203 and more distant from the lower layer. Then, a coil 12 in a completely wound shape doesn't prevent the former 3 from reciprocating to turn the coils 12 around adjoining projected poles 201 to 203. Moreover, the range to winding area around projected poles 201 to 203 is enlarged, while the total wire length of the coil 12 becomes shorter. As a result, a motor with small coil resistance and a larger torque constant can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating magnetic field generating coil for an electromagnetic rotating machine having a core having salient poles in a radial direction with respect to a rotating shaft, and particularly to a spindle motor used for information recording / reproducing equipment. Relates to the configuration of the rotating magnetic field generating coil.

[0002]

2. Description of the Related Art In recent years, information recording / reproducing devices such as 3.5 "floppy disk drives have become smaller and thinner, and the main element technology is to reduce the size and thickness of spindle motors. Due to space limitations, the starting torque and the maximum load torque at rated rotation are reduced, the head and media are attracted, the motor cannot rotate, and the load torque becomes large, the rotation accuracy deteriorates and read / write error occurs. May occur frequently.
Therefore, without reducing the starting torque and maximum load torque,
How to design a small and thin spindle motor is an important issue.

3 (a) and 3 (b) show a conventional winding method for a rotating magnetic field generating coil (hereinafter, simply referred to as coil) of a motor of this type. 3 (a) and 3 (b) are drawn by the one-angle method, and FIG. 3 (a) is a portion seen from the arrow C direction of the laminated core 2 of the motor in FIG. 3 (b), taken along broken line BB '. FIG. 4 is a cross-sectional view showing a state in which a wire rod is wound around salient poles 202. The cross section is indicated by diagonal lines. The mounting holes 5 are holes for fixing the laminated core 2 to a motor base (not shown) or the like. 3B is a partial plan view of the laminated core 2 seen from the direction of arrow A in FIG. 3A, in which the salient pole 201 of the laminated core 2 obtained by laminating three cores 1 is applied to the former 3 and the former 3. It shows that the wire 4 is wound by using. In FIG. 3, the former is used as the winding jig, but the same applies to the nozzle. The former 3 repeats the reciprocating motion along the radial direction arrow D while guiding the wire 4 with the tip portion 301 of the former. The wire rod 4 rotates around it while being guided by the former 3, so that the ultimate 201
Wrapped around. In FIG. 3B, the former 3
Is cut through its central axis for clarity. Further, the wire rod has already been wound on the salient pole 202, and the salient pole 203 has not yet been wound.

Next, the winding will be described in detail. Figure 3
In the example shown in (a), the copper wire with a wire diameter of 0.21 mm is the first
Layer 14 turn, second layer 13 turn, third layer 14 turn,
The fourth layer has 13 turns, for a total of 54 turns. Since the number of salient poles of the laminated core 2 is 15 and the number of phases of the coil is 3, 54 × 5 = 270 turns per phase. The coil resistance value is about 1.9Ω per phase. Number of turns 27
The 0 turn is optimized to achieve the target torque characteristic, and since the number of turns of the four layers is set to be almost the same, it is set to be smaller than the maximum possible number of turns of each salient pole of 23 turns. Also, because it is a thin motor, the number of layers is four.
Limited to layers. As shown in FIG. 3B, the wire 4 is wound on the outer circumference side of the salient pole. As can be seen from FIG. 3B, the tip of the former 3 hits the coil 6 wound on the adjacent ultimate 202, and the inner circumference side Because it cannot be wrapped around.
This is the same for other winding jigs such as nozzles.

FIG. 4 shows the torque-rotational speed characteristics (8, 9 ,, 9) of the motor when the winding core unit designed in FIG. 3 is used.
10 and 11) and the calculation result of the torque-current characteristic (7) are shown. In the torque-rotation speed characteristic, the curves 8 and 9 are the curves 10 and 11 when the rotation speed control is not performed.
The figures show the cases where the rotational speeds are controlled at 300 rpm and 360 rpm, respectively. Curve 8 is the characteristic when the two-phase excitation drive is performed, and curve 9 is the characteristic when the three-phase excitation drive is performed.

As shown in the figure, when the internal load torque of the motor is 7 gfcm, the starting torque is 110 gfcm, and the maximum load torques are 75 gfcm and 70 gfcm at 300 rpm and 360 rpm, respectively. This is a value that does not sufficiently satisfy the target characteristics (starting torque 100 gfcm or more, maximum load torque 70 gfcm). Also,
The design value of the power consumption of the motor at the rated load torque of 40 gfcm is 0.732w.

[0007]

First, the concept of the motor characteristics will be described, and then the problems of the conventional example will be described.

The motor torque constant is Kt, and the starting current is I
If s, the starting torque Ts is given by the following equation: Ts = Kt × Is ……………………………… (1). The torque constant is proportional to the number of turns of the drive coil (coil 6), and the starting current is inversely proportional to the resistance value R of the drive coil. Therefore, in order to increase the starting torque, it is sufficient to realize a winding method in which the number of turns of the coil is large and the coil resistance value is small. On the other hand, the maximum load torque is the torque value at the rated rotation speed on the straight line connecting the no-load rotation speed ω ₀ (ω ₀ = Vin / Kt: Vin is the power supply voltage value) and the starting torque. If Kt is increased, the maximum value should be obtained at a certain place.

In the above conventional example, the starting torque is larger than the target value by about 10 gfcm, but the maximum load torque is the same value as the target value. In the conventional example shown in FIGS. 3A and 3B, when the number of turns is increased and the torque constant Kt is increased, the coil resistance R increases, and as a result, the starting torque Ts decreases. Further, as the torque constant increases, the no-load rotation speed decreases, so the maximum load torque also decreases. If the number of turns is reduced and the torque constant is decreased, the starting current increases and the starting torque increases.
Since the no-load rotation speed also increases, the maximum load torque also increases. However, since the drive current at the rated load also increases, there is a problem that power consumption increases. Further, since heat loss in the motor drive IC also increases, it is necessary to fully consider the thermal design in the output stage, which may result in a high cost.

Further, in the case of designing a smaller and thinner device than the conventional example, it is impossible to achieve the target characteristics only by designing the winding, and it is necessary to redesign the drive magnet, core, etc. There is a drawback that the amount of investment is generated and the cost of the motor itself is increased due to the change of the magnet material.

[0011]

In order to solve the above-mentioned drawbacks, the present invention proposes a method of winding a coil having a large number of coil turns and a small coil resistance value.

That is, the coil for generating a rotating magnetic field of the electromagnetic rotating machine of the present invention is formed of two or more winding layers wound around each salient pole of each phase, and among the winding layers adjacent to each other, The upper layer has a smaller number of turns than the lower layer, and the upper layer has at least one coil portion wound at a position farther outward in the radial direction from the center of the core than the adjacent lower layer. And the external shape of the rotating magnetic field generating coil wound around the salient pole is such that the winding of the rotating magnetic field generating coil is wound around the adjacent salient pole by using a winding jig such as a former or a nozzle. At this time, it is limited to a range such as a former and a nozzle that does not hinder the radial reciprocating motion of the winding jig with respect to the salient pole. The number of turns in the lower layer is
The maximum possible number of turns is set for the winding range of each salient pole of the core in the radial direction.

With such a winding structure, a motor having a large torque constant and a small coil resistance value, that is, a motor which has a large starting torque and a maximum load torque and consumes less power, is suitable for a small and thin motor. Can be designed.

[0014]

EXAMPLE An example of the present invention will be described with reference to FIG. Descriptions of components and the like indicated by the same numbers as in the conventional example are omitted.

FIG. 1A is a partial sectional view of the laminated core 2 of the motor taken along the broken line BB ′ in FIG. 1B and seen from the direction of arrow C. The wire rod is wound around the salient pole 202. The situation is shown. The cross section is indicated by diagonal lines. FIG. 1B is the same as FIG.
It is a partial top view of the laminated core 2 which looked at (a) from the arrow A direction.

Only the coil 12 is different from the conventional example. That is, the feature is that the wire rod 4 is wound around the salient pole. Figure 1
As shown in (a), the coil is wound in four layers. However, this is a thin motor, so there is a limit in the height direction.
This is because only layers can be wound. As shown, the wire diameter is 0.
A 21 mm copper wire is wound around the first layer 23 turns, the second layer 22 turns, the third layer 5 turns, and the fourth layer 4 turns, for a total of 54 turns. The total number of turns is also set to be the same as the conventional example.
Since the number of salient poles of the laminated core 2 is 15 and the number of phases of the coil is 3, 54 × 5 = 270 turns per phase.
The number of turns of 270 turns is optimized to achieve the target torque characteristic. Since the total number of turns of the third and fourth layers is adjusted, it is considerably less than the maximum possible number of turns. Since the winding positions of the wire rod 4 on the third and fourth layers are set on the outer circumferential side of the salient poles, the tip 301 of the former 3 is disposed on the first and second layers as can be seen from FIG. 1 (b). Since the inner circumference side is inserted without hitting the coil of the salient pole 202, the maximum possible winding number of each salient pole is set to be equal to or close to 23 turns. Therefore, since the average diameter of the coil is smaller than the conventional example for the same number of turns,
The wire length is shortened and the coil resistance value is about 1.8Ω per phase.
Is about 0.1Ω smaller than that of the conventional example. Although the former is used as the winding jig in this embodiment, another winding jig such as a nozzle may be used.

FIG. 2 shows a motor torque-rotational speed characteristic (14, 1) when the winding core unit designed in FIG. 1 is used.
5, 16 and 17) and the calculation results of the torque-current characteristic (13) are shown. In the torque-rotational speed characteristic, the curves 14 and 15 show the case where the rotation speed control is not performed, and the curves 16 and 17 show the cases where the rotation speed control is performed at 300 rpm and 360 rpm, respectively. The curve 14 is the characteristic when the two-phase excitation drive is performed, and the curve 15 is the characteristic when the three-phase excitation drive is performed.

As shown, when the internal load torque of the motor is 7 gfcm, the starting torque is 113 gfcm, and the maximum load torque is 78 gfcm and 73 gfcm at 300 rpm and 360 rpm, respectively. This is a design value that is almost appropriate for the target characteristics (starting torque 100 gfcm or more, maximum load torque 70 gfcm).
The torque can be earned by about 3 gfcm as compared with the conventional example. Further, the design value of the power consumption of the motor at the rated load torque of 40 gfcm is 0.732w, which is the same as the conventional example and does not increase.

Further, another embodiment will be described.

In the embodiment shown in FIG. 1A, the number of turns is set to 23/22/5/4 turns in order from the first layer. However, the winding method for increasing the number of turns by reducing the increase in the coil resistance value is the main method. For the purpose of patent, the number of turns can be changed within the range.

For example, depending on the shape of the salient poles of the core, when two layers are wound on the inner peripheral side, the former 3 is wound when the adjacent salient poles are wound.
If the first layer cannot be wound on the inner side because the inner layer does not need to be wound on the inner side, it is possible to set it so that the inner side of the second layer is not wound, for example, 23/18/9/4 turns. Is.

In the embodiment shown in FIGS. 1 (a) and 1 (b), the third layer and the fourth layer are wound on the outer peripheral side. However, the third layer and the fourth layer should be wound on the inner peripheral side within a range where they do not abut the former 3. Is also possible. When the uppermost layer is on the inner peripheral side, it becomes easier to pass the wire rod 4 from the salient pole that has finished winding to the salient pole that starts winding.

In this embodiment, the wire diameter is 0.21 mm and the number of layers is four, but it is also possible to change these parameters within the range permitted by the winding space of the motor for optimum design.

[0024]

As described above, by winding such that the coil resistance value becomes smaller with respect to the number of turns of the coil, a motor having a large torque constant and a small coil resistance value, that is, There is an effect that it is possible to design a motor that is large in starting torque and maximum load torque and consumes less power, and that is suitable for miniaturization and thinning.

[Brief description of drawings]

FIG. 1A is a view for explaining one embodiment of the present invention,
FIG. 3B is a partial cross-sectional view of the laminated core of the motor, and FIG.

FIG. 2 is a graph showing calculation results of rotation speed-torque characteristics and current-torque characteristics of the motor shown in FIG.

3A is a partial cross-sectional view of a laminated core of a motor having a coil of a conventional example, and FIG. 3B is a partial plan view of the laminated core.

FIG. 4 is a graph showing calculation results of a rotation speed-torque characteristic and a current-torque characteristic of a motor having a conventional coil.

[Explanation of symbols]

 1 core 2 laminated core 3 former 4 wire rod 6,12 coil 201,202,203 salient pole 8,9,14,15 rpm-torque characteristic

Claims (2)

[Claims] 1. An electromagnetic rotating machine having a core with salient poles and generating a rotating magnetic field by a multiphase alternating current flowing through a coil wound around a salient pole of each phase using a winding jig such as a former or a nozzle. In the above, the coil wound around each salient pole of each phase is formed of two or more winding layers, and among the winding layers adjacent to each other, the number of turns of the upper layer is smaller than that of the lower layer and The winding layer has at least one coil portion wound at a position radially outward from the center of the core with respect to the adjacent lower winding layer, and is for generating a rotating magnetic field wound around the salient pole. The outer shape of the coil is such that it does not hinder the radial reciprocating motion of the winding jig with respect to the salient pole when the winding of the rotating magnetic field generating coil is wound around the adjacent salient pole by using the winding jig. Generation of rotating magnetic field of electromagnetic rotating machine limited to Coil. 2. The coil for generating a rotating magnetic field according to claim 1, wherein the number of turns of the lower layer of the coil for generating a rotating magnetic field is the maximum possible number of turns with respect to a winding range of the salient pole in the radial direction.