Brushless vibration motor

This application is a continuation of U.S. application Ser. No. 10/308,613, filed Dec. 3, 2002 now abandoned.

1. Field of the Invention

The present invention relates to a compact brushless vibration motor which contains a driving circuit member therein, while being used as a silent call device of a portable telecommunication apparatus such as a cellular phone, a personal communication system, a pager and the like.

2. Prior Arts

The present inventor had proposed a flat compact brushless vibration motor which is disclosed in the Japanese Utility Model laid-open Publication No. Heisei 4-137463 (already registered as Utility Model Registration No. 2549357) and the Japanese Patent laid-open Publication No. Heisei 10-248203.

Furthermore, Japanese Patent laid-open Publication No. 2000-166173 discloses the flat brushless vibration motor.

It is essential that the brushless motor should have a driving circuit member instead of a brush and a commutator. However, the conventional brushless motor has a structure in which no driving circuit member is contained, which also needs to have four or more lead lines to attach the driving circuit member to an outer surface of the motor. Therefore, there is a disadvantage in that the brushless motor cannot be handled as a DC motor having two electric terminals typically.

Furthermore, since a stator of the typical brushless motor has a plurality of armature coils which are evenly arranged around a periphery of the stator, there is a problem in that the electric parts including the driving circuit member and an integrated circuit (hereinafter, referred to as an IC) cannot be contained in the brushless motor.

Therefore, the present invention has been developed to solve the above-mentioned problems by making allowance for scarifying an efficiency of a brushless vibration motor as substantially operating in a non-load.

It is an object of the present invention to provide a compact brushless vibration motor containing a driving circuit member therein, thereby handling the brushless vibration motor as like a typical DC motor.

In order to accomplish the objects of the present invention, there is provided a brushless vibration motor comprising: an eccentric rotor having a rotor case, a magnet which has plural magnetic poles and which is arranged on an inner peripheral surface of the rotor case and an unbalance device disposed on a portion of an outer peripheral surface of the rotor case; a shaft for supporting the eccentric rotor; a housing for supporting the shaft, which has a stator base and a cover for enclosing the rotor; a stator for driving the rotor, which is disposed on the stator base to be around the shaft and which has a plurality of armature coils; and a circuit member for applying electric current to the stator, which is disposed at a predetermined portion on the stator base.

According to the present invention, particularly, the stator preferably is a cored type of stator including a plurality of salient poles on which the armature coils are respectively wound.

The stator includes at least two salient poles on which the armature coils are respectively wound, which is cooperated with the magnets having a southern magnetic pole and a northern magnetic pole alternatively arranged, leaving a radial gap therebetween.

Furthermore, the stator is consisting of at least two salient poles on which armature coils are respectively wound and which are arranged at an angular pitch of integer times to a width of a magnetic pole, and the driving circuit member having at least one sensor.

In the brushless vibration motor according to the present invention, a rotor cover is mounted on the stator to cover the eccentric rotor.

According to the present invention, the stator may include air-core armature coils.

According to the present invention, furthermore, the stator is accomplished by means of at least two three-phase air-core armature coils arranged at an angular pitch of 60 degrees.

According to the present invention, the driving circuit member may have no sensors.

According to the present invention, the stator has at least two air-core armature coils arranged at an angular pitch of integer times to a width of a magnetic pole, and a driving circuit member including at least one sensor.

According to the present invention, a rotor cover can be preferably mounted on the stator to cover the eccentric rotor.

According to the present invention, the brushless vibration motor contains a driving circuit member therein, resulting in only having two electricity supplying terminals, for example a plus pole terminal and a minus pole terminal.

According to the present invention, since a cored type of stator is used for the brushless vibration motor, parts having a relatively large height corresponding to a thickness of the stator can be mounted onto the motor.

According to the present invention, since the motor is a three-phase motor, no sensor may be adapted for the brushless vibration motor.

According to the present invention, one-phase type or two-phase type of one hole sensor can be mounted onto the brushless vibration motor.

According to the present invention, the brushless vibration motor has no danger, which can be easily handled.

According to the present invention, no three-phase sensor needs to be adapted for the brushless vibration motor.

According to the present invention, the brushless vibration motor may have one-phase type or two-phase type of one sensor.

According to the present invention, the brushless vibration motor has no danger, which can be easily handled.

Other features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a cored brushless vibration motor according to a first embodiment of the present invention, in which the brushless vibration motor is a three-phase DC motor to have a radial gap between a stator and a rotor;

FIG. 2 is a longitudinally sectional view of the brushless vibration motor shown in FIG. 1 ;

FIG. 3 is a cross-sectional view of the brushless vibration motor according to a first modified example of the present invention, shown in FIG. 1 ;

FIG. 4 is a cross-sectional view of the brushless vibration motor according to a second modified example of the present invention, shown in FIG. 1 ;

FIG. 5 is a cross-sectional view of the brushless vibration motor according to a third modified example of the present invention, shown in FIG. 1 ;

FIG. 6 is a cross-sectional view of a cored brushless vibration motor according to a second embodiment of the present invention, in which the brushless vibration motor has a radial gap between a stator and a rotor;

FIG. 7 is a cross-sectional view of the brushless vibration motor according to a first modified example of the present invention, shown in FIG. 6 ;

FIG. 8 is a cross-sectional view of a cored type of brushless vibration motor according to a third embodiment of the present invention, in which the brushless vibration motor has an axial gap between air-core armatures and a rotor;

FIG. 9 is a longitudinally sectional view of the brushless vibration motor shown in FIG. 8 ;

FIG. 10 is a cross-sectional view of the brushless vibration motor according to a modified example of the present invention, shown in FIG. 9 ; and

FIG. 11 is a cross-sectional view of a cored brushless vibration motor according to a fourth embodiment of the present invention, in which the brushless vibration motor has an axial gap between air-core armatures and a rotor.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 and 2 show a cored type of a compact brushless vibration motor that is a three-phase DC motor and which has a radial gap between a stator and a rotor. That is, a stepped shaft supporting portion 1 a is formed in such a manner of burring a center portion of a stator base 1 which is a part of a housing H. Then, a shaft 2 is press-fitted into the shaft supporting portion 1 a . A stator core 4 is mounted onto the shaft supporting portion 1 a with leaving a core cover (not shown) therebetween, which has a plurality of armature coils 3 a , 3 b and 3 c respectively wound on salient poles 4 a , 4 b and 4 c to establish a stator S.

The feature of the present invention is that three salient poles are removed from the stator having six salient poles which are arranged around a core of the stator at an even angular pitch of 60 degree, so as to form a space K in the stator base 1 , and then a driving circuit member 1 c having IC and chip typed electric parts attached on a glass fiber epoxy substrate 1 b is contained in the brushless vibration motor.

Here, it is preferable that a narrow coil is wound on the salient poles several times in order to obtain a performance equivalent to that of a series of armature coils opposite each other.

Meanwhile, a rotor R is comprised of a cylindrical rotor case 5 in which notches 5 a are formed in a ceiling portion thereof in order for the rotor case 5 to have a light weight and a small amount of eccentricity, and a narrow cylindrical magnet 6 securely attached on an inner side of the rotor case 5 , which is rotatably mounted on the shaft by means of a bearing 5 c installed at the center portion of the rotor case 5 . The rotor case 5 has a semi-cylindrical weight 5 b attached to an outer periphery surface thereof by welding, so as to reinforce an eccentric force of the rotor R. The magnet 6 has four southern magnetic poles and four northern magnetic poles alternatively arranged on the inner periphery of the rotor case 5 to help an operation of the rotor R.

Furthermore, a reference numeral 1 d in the drawings denotes a dummy core risen from the stator base 1 to evenly distribute magnetic force from the magnet, and a reference character C indicates a cover attached at an edge to the stator base 1 , which performs a protection of the eccentric rotor and which prevents a danger due to a roughness of an outer surface of the eccentric rotor when the rotor rotates.

The vibration motor is operated in a three phase unipolar manner or a bipolar manner without a sensor. The principle of operating the vibration motor is well known to those skilled in the art. Therefore, the description of the principle of the operating the vibration motor will be omitted.

Hereinafter, modified examples of the embodiment of the present invention or another embodiments of the present invention will be described. Like reference numerals are used to denote the like member or members having the same function, of which description will be omitted. Further, the cover C may not be shown in the following embodiments and modified examples.

FIG. 3 shows the first modified example of the present invention, in which the stator S 1 is provided with two salient poles having the armature coils 3 a and 3 b to reduce manufacturing cost. There is the stator S 1 in which four armature coils are removed from six armature coils arranged in the typical stator. Thereby, it is possible that the above mentioned circuit member 1 c is disposed at a space K 1 in the vibration motor, as described above. Where the driving circuit member has no sensor, the vibration motor can be operated in a bipolar manner because it is not needed one-phase terminal among the three-phase terminals. Thus, the driving circuit member 1 c can be reasonably received in the space K 1 in the vibration motor.

FIG. 4 shows the brushless vibration motor according to a second modified example of the present invention, in which a stator S 2 has four salient poles 4 a , 4 b , 4 c and 4 d of which one salient pole 4 a is opposite to another salient pole 4 d . That is, the stator S 2 has the same structure as that of the first embodiment of the present invention, except that the armature coils 3 a and 3 d respectively wound on the opposite salient poles 4 a and 4 d are in series connected with each other. Therefore, there is a space K 2 in the motor, which is corresponding to that of disposing the two salient poles and in which the circuit member 1 c can be disposed. It is preferable to mount a bare chip typed circuit member rather than an IC having no a sensor in this space K 2 .

FIG. 5 shows a brushless vibration motor according to a third modified example of the present invention, in which a stator S 3 has salient poles 4 e , 4 f and 4 g arranged at an even angular pitch of 80 degrees on which armature coils 3 e , 3 f and 3 g are respectively wound. A magnet having three southern magnetic poles and three northern magnetic poles alternatively arranged in the rotor case faces the stator S 3 , radially leaving a gap therebetween, which constructs the eccentric rotor R 3 .

In this case, the space K 3 has an area capable of receiving one or more armature coil, in which the circuit member 1 c can be mounted.

Furthermore, an angular pitch of three salient poles can be changed in a range of 70 degrees to 100 degrees by varying the size and shape of the salient poles.

FIG. 6 shows a compact cored brushless vibration motor a ccording to the second embodiment of the present invention, in which air-core typed armatures having a one hole IC are adapted to the brushless motor.

That is, a stator S 4 drives an eccentric rotor R 4 having a magnet that has two southern magnetic poles and two northern magnetic poles that are alternatively arranged on an inner periphery of a rotor case. The stator S 4 includes a stator core 44 which is disposed on a stator base 11 to have two salient poles 44 a and 44 b which are arranged at an angular pitch (i.e. 90 degrees) corresponding to a width of a magnetic pole, and armature coils 33 a and 33 b respectively wound on each salient pole. As a space K 4 , capable of receiving two salient poles, is formed in the brushless motor, the driving circuit member including the one hole IC used as a sensor and another electric part can be received in the space K 4 .

FIG. 7 shows a brushless motor according to a modified example of the present invention shown in FIG. 6 , in which a stator S 5 is provided with three salient poles. That is, one salient pole 44 c is opposite to another salient pole 44 a . An armature coil 33 c wound on the salient pole 44 c is, in series, connected to an armature coil 33 a opposite thereto.

In this case, there is a space K 5 enough to receive an armature coil in the brushless motor, in which the circuit member 11 c having the one hole IC and another electric parts is received. Further, a narrow cylindrical magnet 66 , constructing an eccentric rotor R 5 , has six magnetic poles of which three southern magnetic poles and three northern magnetic poles are alternatively arranged on the inner periphery of the rotor case.

FIGS. 8 and 9 show a compact brushless vibration motor a ccording to a third embodiment of the present invention, in which the vibration motor has no core. In those drawings, a bearing 111 a is integrally secured as a shaft supporting port ion to a center portion of a stator base 111 . Three air-core armature coils 333 a , 333 b and 333 c are disposed around the bearing 111 a on the stator base 111 at an even angular pitch of 60 degrees. Thus, a space K 6 having a region in which three armature coils are disposed is formed in the brushless motor, in which the driving circuit member 1 c having no a sensor is mounted.

Furthermore, a thrust bearing 111 b consisting of a ball is disposed on a bottom surface of a thrust bearing 111 a in order to decrease a sliding area of a shaft 22 for a purpose of reducing a braking force of a magnet 666 disposed in the rotor.

Meanwhile, the brushless vibration motor according to the third embodiment of the present invention has the same structure as that of the brushless vibration motor according to the first embodiment of the present invention, except that a ring type magnet 666 has four southern magnetic poles and four northern magnetic poles which are alternatively arranged, which is securely attached to a ceiling portion of the rotor case 55 , and that the shaft 22 is press-fitted in a burring portion 55 a . Such eccentric rotor R 6 is rotatably mounted on the bearing 111 a . An unbalance device such as an eccentric weight 55 b is directly adhered to a part thereof to a periphery of a ring type of the flat magnet 666 .

FIG. 10 shows a brushless vibration motor according to a first modified example of the present invention as shown in FIG. 8 , in which a stator S 7 has three air-core armature coils 333 d , 333 e and 333 f arranged at an even angular pitch of about 80 degrees. The stator S 7 faces a thin cylindrical magnet 666 , which has three southern magnetic poles and three northern magnetic poles alternatively arranged, leaving a gap therebetween.

In the case, there is a space K 7 in the brushless vibration motor, which corresponds to an area of an armature coil and in which the circuit member 1 c is disposed.

Furthermore, an angular pitch of three air-core armature coils can be changed in a range of 70 degrees to 100 degrees in a manner of changing the size and shape of the armature coil.

FIG. 11 shows a brushless vibration motor according to a second modified example of the present invention, in which a stator S 8 has two air-core armature coils 333 g and 333 h arranged on the stator base at an angular pitch of 90 degrees. There is a space K 8 in the brushless vibration motor, which corresponds to an area of two armature coils and in which the circuit member 11 c is disposed.

An eccentric rotor facing the stator S 8 has a magnet in which two southern magnetic poles and two northern magnetic poles are alternatively arranged at an angular pitch of 90 degrees. However, the magnet may have six magnetic poles according to the angular pitch of the magnetic poles.

In addition, three air-core armature coils, as not shown, may be arranged at an angular pitch of 90 degrees in the brushless vibration motor, thereby obtaining a space corresponding to an area of an air-core armature coil.

Further, while being mainly mounted on the stator base as a part of the housing in the respective embodiments and modified examples, the shaft supporting portion may be mounted in a cover as the other part of the housing. That is, the shaft supporting portion can be constituted as like that of the brushless vibration motor shown in FIG. 3 of the Japanese laid-open Patent Publication No. Heisei 10-248203 which the present applicant had applied.

Meanwhile, the stator base can be formed with a printed circuit iron board instead of a fiberglass epoxy substrate 1 b , on which the driving circuit member 1 c is additionally mounted. Thereby, emitting heat from the driving circuit member can be preferably performed.

While the present invention has been particularly shown and described with reference to particular embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.