JPH0965595A - Small dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cost reduction and a simplified process by reducing the number of parts to be used in the pulling-out stopper part of a rotating structure for a small DC motor. SOLUTION: This DC motor is formed as follows: A yoke 14 is integrally- provided in the lower surface of a lower spindle magnet 8 in the rotating structure of a motor and pierced by a through-hole 15. The attracting force caused by the leaking flux of the lower spindle magnet 8 passing through the through- hole 15 is made to work upon the base 1 of a magnetic member, thus retaining the rotating structure of the motor against the base 1 so as not to come off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to household appliances and information and OA equipment such as CDs, DATs, radio-cassettes, and Cs.
The present invention relates to a brushless small DC motor that is used as a drive source for a D-ROM, FDD, camera, etc., and is thin and small, has torque, has a long life, and is maintenance-free.

[0002]

2. Description of the Related Art Small motors are widely used in various fields, and the type and drive system of a magnet as a constituent member is selected based on the required function of each. There are various types of small motors, for example, AC motors (induction motors) used in fans, water pumps, washing machines, FDDs, CD-ROMs, VTs.
There are DC motors (brushless DC motors) used in R, facsimiles, etc., stepping motors used in antenna drives, wipers, etc.

Recently, small DCs have been used for OA equipment and the like.
Motors are often used. The reasons are: 1. It operates stably over a wide range of speeds. 2. Be agile as needed. 3. It is small and can produce great power. 4. Reliable with microcomputer control. and so on.

Due to the above reasons, small DC motors are used for driving audio CDs, laser disks, CD-ROMs, write-once optical disks, rewritable optical disks and the like. Specifically, there are a spindle motor for rotating the disc, a feed motor for moving the optical pickup, and a loading motor used for taking out the disc. Above all, a spindle motor is required to have a large torque as the rotation speed of the disk increases to double speed or quadruple speed.

There are various small DC motors having various structures according to the purpose of use, but there are some that use two sets of magnets and coils to increase the rotational torque.
The small DC motor is fixed on a substrate called a base, but there are some methods for preventing the rotary component from slipping off in the thrust (axial) direction. Two methods will be described below, a retaining method for the rotating component using washers and a retaining method for the rotating body using retaining metal plates.

First, a method for preventing the rotor from coming off using washers will be described. FIG. 2 shows an enlarged sectional view of the small DC motor. The base 1 is made of a thin plate of magnetic material, and a cylindrical bearing portion 2 having a hardness equal to that of metal or metal is fixed by press fitting. The bearing portion 2 includes
A rotating shaft 3 having a metal or a hardness similar to that of metal is rotatably fitted, and the rotating shaft 3 stands perpendicular to the base 1. The turntable 4 is formed in a disk shape, and is press-fitted and coupled to the upper portion of the rotary shaft 3 so that the base 1 and the lower surface of the turntable 4 are parallel to each other.

A ring-shaped upper spindle magnet 5 is adhered to the lower surface of the turntable 4. Below the upper spindle magnet 5, a spindle coil substrate 7 having a spindle coil 6 bonded to the front and back is arranged, and a current is supplied to the spindle coil 6 on the surface of the spindle substrate 7 although not shown. Wiring is provided for. The spindle coil 6 is formed by winding a copper wire, and is usually arranged in a concentric circle on the spindle coil substrate 7. The thickness in the vertical direction is to reduce the thickness of a small DC motor. It is thin. As seen from above, there are various shapes such as triangles and squares that have been devised to increase the force in the direction of rotation.
The spindle coil substrate 7 of the spindle coil 6
Regarding the position above, there is also a one-sided half on a concentric circle. The upper spindle magnet 5 is magnetized so as to generate a magnetic flux in the vertical direction in order to cause the magnetic flux to enter the spindle coil 6. In addition, the spindle coil substrate 7 includes the upper spindle magnet 5
And the spindle coil 6 are not in contact with each other, and are fixed on a supporting projection standing on the base 1 and arranged in parallel with the turntable 4. Below the spindle coil substrate 7, a ring-shaped lower spindle magnet 8 similar to the upper spindle magnet 5 and a yoke 9 bonded to the lower spindle magnet 8 and also serving as a supporting member thereof are provided. , The lower spindle magnet 8 is the spindle coil 6
It is arranged in parallel with the turntable 4 so as not to come into contact with. Like the upper spindle magnet 5, the lower spindle magnet 8 is magnetized so as to generate a magnetic flux in the vertical direction in order to cause the magnetic flux to enter the spindle coil 6.

A lower portion of the fixing member 10 is connected to the yoke 9, and an upper portion thereof is press-fitted into the lower surface of the turntable 4. The rotary shaft 3 has a cylindrical shape so as to pass through without contacting the center, and the turntable 4 and the upper and lower spindle magnets 5 and 8 are connected to each other.

As a result, the turntable 4, the upper spindle magnet 5, the lower spindle magnet 8, the yoke 9 and the rotary shaft 3 are integrated to form a rotary component and rotate as the rotary component. As a force for rotating the turntable 4, a driving force generated by passing a current through the spindle coil 6 is used.

The rotary shaft 3 penetrates through the base 1, and a groove is provided in a portion of the rotary shaft 3 below the base 1. By mounting a washer 11 in this groove, the rotary component is held on the base 1.

Next, a retaining method of the rotary component using the retaining sheet metal will be described. The sectional view is shown in FIG. The basic configuration is the same as when a washer is used. Rotating shaft 3
The lower end of the abuts against the upper surface of the base 1 without penetrating the base 1. The diameter of the yoke 12 is larger than that of the lower spindle magnet 8. The base 1
A retaining metal plate 13 having a shape partially covering the upper portion of the yoke 12 is fixed on the top. The retaining metal plate 13 prevents the rotary component including the yoke 12 from falling off the base 1.

[0012]

However, in the method for preventing the rotating body from coming off by the washer shown in FIG. 2, a washer must be prepared in addition to the components of the rotating component, and the rotating shaft 3 must be provided. Processing to cut the groove is also required.
Further, also in the retaining method of the rotating component by the retaining sheet metal 13 shown in FIG. 3, similarly, the retaining sheet metal 13 must be prepared, and the retaining sheet metal 13 is fixed on the base 1. Also in this case, new processing and parts are required, and the number of parts and the number of works increase as a retaining portion of the rotary component.

The present invention has been made in order to solve the above problems. By utilizing the property of the components of the rotary component, the rotary component can be retained and retained on the base, and the number of components of the retainer can be reduced and the cost can be reduced. Compact D for down and simplification of process
The purpose is to provide a C motor.

[0014]

In order to achieve the above object, the present invention provides a yoke integrally with the lower surface of a lower spindle magnet in a rotary component of a motor, and a through hole is formed in the yoke. A small DC motor is constructed in which an attracting force due to a leakage magnetic flux of a lower spindle magnet passing through a magnetic material is applied to a base of a magnetic material so that a rotating component of the motor is retained and held in the base.

[0015]

In the above structure, the lower spindle magnet is attracted to the base by using the leakage flux of the lower spindle magnet in the rotating component of the motor, and the rotating component including the lower spindle magnet does not require a special holding member. It is retained and retained on the base.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A small DC motor according to an embodiment of the present invention will be described below with reference to the sectional view of FIG. In addition,
The same components as the components of the small DC motor of the conventional example described above are designated by the same reference numerals and described.

As shown in the figure, the base 1 is made of a thin plate of magnetic material, and a metal or a cylindrical bearing portion 2 having a hardness similar to that of metal is press-fitted and fixed to the base 1. A rotating shaft 3 having a hardness equal to that of metal or metal is fitted into the bearing portion 2, and the rotating shaft 3 stands perpendicular to the base 1. The turntable 4 has a disc shape, and is press-fitted and coupled to an upper portion of the rotary shaft 3 so that a lower surface thereof is parallel to the base 1.

A ring-shaped upper spindle magnet 5 is bonded to the lower surface of the turntable 4. Below the upper spindle magnet 5, there is a spindle coil substrate 7 having a spindle coil 6 adhered to the front and back thereof, and on the surface of the spindle coil substrate 7, although not shown, wiring for supplying a current to the spindle coil 6 is provided. It has been subjected. The spindle coil 6 is formed by winding a copper wire, and is usually arranged in a concentric circle on the spindle coil substrate 7. The thickness in the vertical direction is to reduce the thickness of a small DC motor. It's thin. As for the shape seen from above, there are various shapes such as a triangle and a square that have been devised to increase the force in the direction of rotation.
Regarding the position of the spindle coil 6 on the base 1, there is also a concentric circle on one side only. The upper spindle magnet 5 is magnetized so as to generate a magnetic flux in the vertical direction in order to cause the magnetic flux to enter the spindle coil 6. Further, the spindle coil substrate 7 is fixed on a supporting protrusion provided upright on the base 1, and is arranged in parallel with the turntable 4 so that the magnet 5 and the spindle coil 6 are not in contact with each other. There is. Below the spindle coil substrate 7, a ring-shaped lower spindle magnet 8 similar to the upper spindle magnet 5 and the lower spindle magnet 8 are joined together, and the yoke 1 also serves as a support material for the lower spindle magnet 8.
4 is arranged, and the spindle magnet 8 is arranged parallel to the turntable 4 so as not to contact the spindle coil 6. Like the upper spindle magnet 5, the lower spindle magnet 8 is magnetized so as to generate a magnetic flux in the vertical direction in order to cause the magnetic flux to enter the spindle coil 6.

The small DC motor of this embodiment is characterized by the following structure. That is, the yoke 14 has a plurality of through holes 15. The through hole 15 is provided from the bonding surface of the lower spindle magnet 8 toward the upper surface of the base 1, and when viewed from the lower surface of the yoke 14, the central angle is equally divided at a uniform distance from the rotation center. Are arranged as follows.

A fixing member 1 is provided on the lower surface of the turntable 4.
The upper part of 0 is press-fitted. The fixing member 10 has a cylindrical shape so that the rotary shaft 3 can pass through without contacting the center, and connects the turntable 4 and the upper and lower spindle magnets 5 and 8, and the yoke 14 is fixed. It is bonded to the lower part of the member 10. As a result, the turntable 4, the upper spindle magnet 5, the lower spindle magnet 8 and the yoke 14 are integrated to form a rotary component including the rotary shaft 3. As a force for rotating the rotary component, a driving force generated by passing a current through the spindle coil 6 is used.

In the above-mentioned structure, the base 1 is provided with the yoke 1 by the leakage magnetic flux generated from the lower spindle magnet 8 passing through the through hole 15 of the yoke 14.
The rotary component integrally formed with 4 is suction-held.
Although the shape of the through holes 15 is not limited, the holding force of the rotary component of the motor can be adjusted by increasing or decreasing the number and area of the through holes 15.

[0022]

As is clear from the above description of the embodiments, the small DC motor according to the present invention utilizes the leakage flux of the spindle magnet for generating the rotational force, and attracts the rotating component of the motor to the base. By doing so, since the retaining structure of the rotary component is retained, it is possible to reduce the number of parts of the retaining structure and reduce the cost and simplify the process.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a small DC motor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a conventional small DC motor.

FIG. 3 is a cross-sectional view showing the configuration of another conventional small DC motor.

[Explanation of symbols]

 1 Base 2 Bearing 3 Rotating Shaft 4 Turntable 5 Upper Spindle Magnet 6 Spindle Coil 7 Spindle Coil Board 8 Lower Spindle Magnet 10 Fixing Member 14 Yoke 15 Through Hole

Claims (1)

[Claims] 1. A rotating shaft, a turntable mounted on the rotating shaft, upper and lower magnets, a yoke joined to a lower surface of a lower magnet, and a fixing member for integrally fixing the turntable, the upper and lower magnets and the yoke. The rotary component has a structure, a driving coil located between magnets above and below the rotary component, and a base having a bearing for receiving a rotation axis of the rotary component. The base is made of a magnetic material. And a through hole through which the leakage magnetic flux of the lower magnet passes, is formed in the yoke of the rotating component, and the attracting force of the leakage magnetic flux is applied to the base to hold the rotating component in the base so as to be retained. Small DC motor.