JPH0720352B2 - Rotating core of small motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotary core of a small motor having three core salient poles.

Structure of conventional example and its problems In recent years, there has been a strong demand for high-performance, low-priced small DC motors, especially at low prices, the cost competition of finished products is fierce, and the motors among the parts used in those products are Since it is more expensive than the parts, it is effective to reduce the motor price as a cost reduction. Factors that influence the motor cost include the material of the magnet, the material of the bearing, the structure of the communication section, the number of core slots, etc. The present invention focuses on the number of core slots. Now, it is possible to reduce the coking and torque unevenness of the motor characteristics by increasing the number of core slots, but the cost also increases at the same time because the number of winding and connecting processes increases. Therefore, a low-priced motor can be supplied by reducing coking and torque unevenness with three slots, which have a small number of slots.

Conventionally, the rotary core of a three-slot small DC motor has a shape as shown in FIG. That is, 30 is a core salient pole right, 31 is a core salient pole left, and 32 is a slot. However, the core salient pole right 30 and the core salient pole left 31 have symmetrical shapes, and because of three slots, the coking and torque unevenness are large to some extent. For example, in a three-slot symmetrical core with an outer diameter of 23 mm, the effective total flux changes depending on the rotational position of the core. In Fig. 5, the core position is 0 °, and in Fig. 6, the core position is 30 °.
Magnetic flux distribution at ° is shown. In FIGS. 5 and 6, 33 is a magnet, 34 is a frame, 35 is a magnetic flux distribution, 36
Is the rotating core. The effective total flux in Fig. 5 shows the maximum value at 3900 Maxwell, and the effective total flux in Fig. 6 shows the minimum value at 3500 Maxwell. The coking torque is 1.7 gcm due to the change of this effective total flux. Has a large value. In order to reduce the coking and torque unevenness with three slots, it is common to add a skew at the time of stacking the cores, but there is a problem that the process becomes complicated and the cost increases.

OBJECT OF THE INVENTION An object of the present invention is to provide a small direct current motor with low cocking and low torque unevenness at low cost.

Configuration of the Invention The present invention includes three core salient poles formed by three slots, and a pair of protrusions projecting from the tips of each core salient pole on both sides of the adjacent slots with different protrusion amounts. It is a thing.

According to the configuration of the present invention, since the three salient poles formed by the three slots are formed asymmetrically,
The coking torque and torque unevenness of the three slots can be reduced, and a small motor can be realized at low cost. Furthermore, since it has 3 slots, it can be self-started and there is no problem of indeterminate rotation direction.

Description of Embodiments One embodiment of the present invention will be described with reference to FIGS. 1 to 3. That is, this rotating core is
One core salient pole 2 is formed, and a pair of protrusions 3 and 4 are protruded in the slots on both ends of the core so that the protrusion amounts a and b of the protrusions 3 and 4 are different.

The effective total flux of the core of this embodiment configured as described above will be described. Similar to the configuration of the conventional example described above, the core outer diameter is 23 mm and the core has a three-slot core.
The magnetic flux distribution diagrams for the asymmetric type of 3 and 4 with a symmetry degree of 2.6 mm are shown in FIG. 2 when the core position is 0 ° and in FIG. 3 when the core position is 30 °. 2 and 3, 5 is a magnet, 6 is a frame, 7 is a magnetic flux distribution, and 8 is a rotating core. As a result of the measurement, the effective total flux when the position of the rotating core 8 was 0 ° showed the maximum value at 3900 Maxwell, and the effective total flux when it was 30 ° showed the minimum value of 3600. As a result, the minimum value is 100 Maxwell better than the conventional core, so the coking torque is 1.3gcm, which is 23% better than the conventional symmetrical core.

As described above, according to this embodiment, the coking torque is improved by 23% by using the asymmetric core having the outer diameter of 23 mm and the three-slot core salient pole portion with the symmetry degree of 2.6 mm.

EFFECTS OF THE INVENTION As described above, according to the present invention, since the three core salient poles formed by the three slots are each formed asymmetrically, the coking torque and the torque unevenness of the three slots can be reduced, and A small motor can be realized at low cost. Furthermore, since it has 3 slots, it can be self-started, and there is an effect that there is no problem of indefinite rotation direction.

[Brief description of drawings]

FIG. 1 is a plan view of a three-slot core in one embodiment of the present invention, FIG. 2 is a magnetic flux distribution diagram at a core position of 0 °, and FIG. 3 is a magnetic flux distribution diagram when the core is moved to a 30 ° position, FIG. 4 is a plan view of the conventional example, FIG. 5 is a magnetic flux distribution diagram of the core position of 0 °, and FIG. 6 is a magnetic flux distribution diagram of the core moved to the 30 ° position. 1 ... slot, 2 ... core salient pole, 3,4 ... projection, 8 ...
… Rotating core

Claims (1)

[Claims] 1. A small-sized apparatus comprising three core salient poles formed by three slots and a pair of projecting portions projecting from the tips of each core salient pole on both sides of the adjacent slots with mutually different projecting amounts. The rotating core of the motor.