JPH08140303A - Radial gap coreless dc motor - Google Patents

Abstract

PURPOSE: To obtain a radial gap coreless DC motor by which a magnetic circuit is improved, whose efficiency is made high even in a slender tube shape, which is started necessarily when the coreless motor is used as a brushless vibrating motor, in which a part of a magnetic field is used as a centrifugal-force generation means and in which it is not required to add an eccentric weight for an output shaft. CONSTITUTION: In a radial gap coreless DC motor, a cylindrical coreless winding and a magnet by which a magnetic field is given to the cylindrical coreless winding from the radial direction are arranged at the inside of a housing H. The magnet is constituted of a first cylindrical magnet 5 which is arranged at the inside of the cylindrical coreless winding 6 and of a second magnet 9 which is arranged at the outside. Preferably, the cross-section in the radial direction of the housing is formed as a short diameter part and a long diameter part, and one pair of second C-shaped magnets 9 are arranged in the long diameter part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in the characteristics of radial air gap type DC coreless motors, and more particularly to those suitable for use in vibration generating air gap type DC coreless motors as silent call means for pagers.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a cylindrical Choles DC motor M is used as a silent call means such as a pager.
An eccentric weight W made of a tungsten alloy is disposed on the output shaft S of the above, and the centrifugal force of the eccentric weight W is used to generate vibration during rotation, which is one of the application means of the cylindrical DC motor. Are known. At present, a motor having such a structure, which has a diameter of about 6 mm and a size of 7 mm including a mounting holder, is widely used.

[0003]

However, the thickness (that is, the diameter) is required to be 4.5 mm or less for mounting on a thin portable device such as a card type pager which has recently begun to appear on the market. If the product is simply made into a small size, the characteristics deteriorate, that is, the current consumption is large,
Moreover, there are drawbacks such as high rotation speed and poor battery life and poor sensation.

[0004]

OBJECT OF THE INVENTION The object of the present invention is that the thickness is about 4.2 mm, but there is some margin in the lateral direction. That is, it is intended to improve the magnetic circuit by being created from the characteristics of the structure of the non-cylindrical DC motor, and to provide a small DC motor that is thin cylinder type and efficient. Another object of the present invention is to use a part of the field as a centrifugal force generating means,
(EN) It is possible to provide a brushless coreless vibration motor that is reliably started and does not need to add an eccentric weight to an output shaft.

[0005]

The above object is to provide a cylindrical coreless winding inside the housing and a magnet for applying a magnetic field to the cylindrical coreless winding in the radial direction. In the radial air gap type DC coreless motor described above, the magnet can be achieved by being constituted by a first magnet disposed inside the cylindrical coreless winding and a second magnet disposed outside the cylindrical coreless winding. More specifically, it can be achieved by forming the radial cross section of the housing into a minor diameter portion and a major diameter portion and arranging a pair of second magnets in the major diameter portion, as in the invention described in claim 2.

Alternatively, for application to a brushless motor, as in the invention described in claim 3, the cylindrical coreless winding is fixed to a part of the housing, and the first magnet and the second magnet are integrated. It can be achieved by rotating it. The application of this to a vibration motor can be achieved by decentering at least the center of gravity of the second magnet with respect to the shaft, as in the invention described in claim 4.

[0007]

According to the object of the invention described in claim 1, since the magnetic field is applied from both the inner side and the outer side of the cylindrical coreless winding, the operating point permeance coefficient is increased and the characteristics are improved. According to the means for achieving the object of the invention as set forth in claim 2, since the substantial thickness is the short diameter portion, it is contributed to the thinning of the device by laying it sideways for use.

According to the means for attaining the object of the invention described in claim 3, a highly efficient brushless type DC coreless motor can be obtained. According to the means for achieving the problems of the invention described in claim 4,
The magnet can be easily activated, and the second magnet acts as an eccentric weight, so that the eccentric weight is not necessary outside.

[0009]

[First Embodiment] FIG. 1 shows an axial sectional view of a radial air gap type DC coreless motor as a first embodiment of the present invention. A case 1 constituting a housing H is as shown in FIG. The diametrical cross section is an oval type consisting of a major axis and a minor axis. The case 1 is an ultra-thin cylinder having a long diameter of 5 to 5.2 mm and a short diameter of 4 to 4.2 mm. Inside the case 1, a shaft 2 is rotatably supported by a bearing 3 in the center, and the bearing 3 is fixed to an integrated yoke 4 which is erected inward from the bottom of the case 1. A cylindrical first magnet 5 is arranged. Outside the magnet 5, a cylindrical coreless winding 6 is fixed to a holder 8 which is integral with a flat plate commutator 7 at one end through a slight gap.

A pair of C-shaped second magnets 9, 9 are arranged outside the cylindrical coreless winding 6 to face the inner cylindrical magnet 5 to form a magnetic field.
In the figure, reference numeral 10 is a brush that is in sliding contact with the flat plate commutator 7, and its base end is placed on a bracket 11 that also serves as a brush base. The bracket 11 is arranged in the opening of the case 1, and is connected to the brush 10 from the pair of lead wires 12 and 13.
Is to be powered. By doing so, the operating point permeance coefficient can be made high by the first cylindrical magnet and the second pair of C-shaped magnets.

[0011]

[Second Embodiment] FIG. 3 is a sectional view of an essential part in the axial direction applied to a brushless vibration motor as a second embodiment of the present invention, and FIG. 4 is a sectional view of the essential part in the radial direction of the motor. It is a figure. In the figure, reference numeral 14 is a shaft made of magnetic stainless steel, to which a cylindrical magnet 15 is directly fixed, and further, a cylindrical coreless winding 6 is fixed to a bracket 16 at one end through a gap to form a stator. A second C-shaped magnet 17 is attached to the outside of the cylindrical coreless winding 6 through a gap in a modified case 18 which also serves as a yoke. The crescent-shaped magnet 1 of the modified case 18
The other side of 7 is formed so as to prevent the magnetic circuit loss by reducing the gap to a position equal to the inner diameter of the magnet 17.

According to this structure, the second externally arranged
Since the C-shaped magnet 17 is largely eccentric with respect to the center, a large centrifugal force is generated during rotation and vibration can be obtained. Moreover, since the first cylindrical magnet 15 generates a magnetic field in all directions, there is no possibility that a starting failure will occur even if it is driven without a sensor.

In the second embodiment, the outer second
Although the magnet is eccentrically used as the vibration motor, the second magnet may be formed in a cylindrical shape to be a normal rotation type without eccentricity.

[0014]

As described above, according to the present invention, the magnetic field is applied by the first magnet having the cylindrical coreless windings arranged inside and the second magnet arranged outside, so that the operating point permeance is improved. A large coefficient can be obtained, and high efficiency can be realized with a small diameter. In particular, if the housing is made of an oval type consisting of a long diameter portion and a short diameter portion, a low profile radial air gap type DC coreless motor can be obtained, and if the second magnet is eccentric, a brushless type A vibration motor having good starting characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a radial air gap type DC coreless motor according to the present invention, which is an axially cutting main part.

FIG. 2 is a cross-sectional view of a main part of the motor in a radial direction.

FIG. 3 is a cross-sectional view of a main part of a radial air gap type DC coreless motor according to a second embodiment of the present invention in an axial direction.

FIG. 4 is a sectional view of the same radial cutting main part.

FIG. 5 is a perspective view of a conventional radial air gap type DC coreless motor for vibration generation.

[Explanation of symbols]

 H housing 1 case 2 axis 5 cylindrical first magnet 6 cylindrical coreless winding 9 C type second magnet 15 cylindrical magnet 17 C type magnet 18 modified case

Claims (4)

[Claims] 1. A radial air gap type DC coreless motor in which a cylindrical coreless winding is arranged inside a housing, and a magnet which gives a magnetic field to the cylindrical coreless winding in a radial direction is arranged. A radial air gap type DC coreless motor comprising a first magnet disposed inward and a second magnet disposed outward. 2. The radial air gap type DC coreless motor according to claim 1, wherein a radial cross section of the housing is formed into a minor diameter portion and a major diameter portion, and a pair of second magnets are arranged in the major diameter portion. 3. The radial air gap type DC coreless according to claim 1, wherein the cylindrical coreless winding is fixed to a part of a housing, and the first magnet and the second magnet are integrally rotated. motor. 4. The radial air gap type DC coreless motor according to claim 3, wherein at least the center of gravity of the second magnet is eccentric with respect to the shaft.