JPH04147470A - Motor - Google Patents

Abstract

PURPOSE:To make the profile of a magnetic recorder thin by providing a stator to the outside of a rotor and designing part of an iron core of the stator to be smaller radially or removed. CONSTITUTION:An outer circumference of an iron core 3a in which a coil 6 is removed is formed to be recessed part 3c as if it were retreated toward the inner circumference, and a rotor 10 whose permanent magnet 9 is fixed to the outer circumference of a ring rotor yoke 8 made of a ferromagnetic metal material integrated with a holder mechanism 7 press-fit or integrated with a rotary shaft 1 is formed on the inside of the stator 3. Moreover, a washer shaped slide member 12 made of a resin or metal of a low friction coefficient is interposed between a rear face of the holder mechanism 7 and an end face of a bearing component 2 toward the support mwchanism 7. Thus, the thin profile of the magnetic recorder is easily attained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electric motor, particularly an electric motor that rotates a recording medium of a magnetic recording device having a magnetic head for reading and writing magnetic recording signals on a recording medium such as a disc-shaped magnetic disk. Regarding.

[Prior Art] The above-mentioned conventional electric motor of this type is, for example, the
The configuration is as disclosed in Japanese Patent No. 5863. That is, as shown in FIGS. 6 and 7, a rotating shaft 1 equipped with a holder [7] that holds a magnetic recording medium 11 is attached to a frame 20 via two bearings, one on the holding mechanism side and the other on the side opposite to the holding mechanism. It is rotatably held by a fixed cylindrical bearing holder 21.

A stator 22 having a donut-shaped iron core is fixed to the outside of the bearing holder 21 with a frame 20 sandwiched therebetween by screws.
A coil 23 is wound around the iron core. A yoke 25 having a permanent magnet 24 fixed thereto facing the stator 22 on its inner peripheral surface is screwed to the end of the rotating shaft 1 on the side opposite to the holding mechanism, and the rotor 26
is configured. The permanent magnet 24 generates magnetic force in the radial direction, and generates rotational torque and torque by the current applied to the coil 23 wound around the iron core of the stator 22. In the figure, reference numeral 27 denotes an index detection element constituting the index detection mechanism, and 28 denotes an index detection magnet also constituting the index detection mechanism.The index detection mechanism generates a -pulse signal in one rotation. Also, 14.1
Reference numeral 5 denotes a magnetic head, which is attached to the frame 20 and is configured to be movable linearly by a sliding member on a support shaft fixed via a member.

This type of electric motor has a rotor 26 disposed outside the stator 22.
It is called an outer rotor type in which the index detecting magnet 28 is located, and the magnetic flux of the index detecting magnet 28 is transferred to the index detecting element 2.
7, and based on this detection, the energization of the coil 23 wound around the iron core of the stator 22 is controlled to rotate.

[Problems to be Solved by the Invention] In the conventional electric motor described above, the rotor 26 is located outside, and the magnetic head 1 moves linearly in the radial direction with respect to the recording medium 11.
4.15 cannot be placed on the plane of the rotor 26, and it is difficult to reduce the thickness of the magnetic recording device.

This invention was made in order to solve these conventional problems, and its purpose is to provide an inner rotor type electric motor that can contribute to making magnetic recording devices thinner and moreover, can rotate recording media with high precision. do.

[Means for Solving the Problems] An electric motor according to the present invention is rotatably held perpendicularly to a frame by bearing parts such as oil-impregnated sintered metal, and includes a holding mechanism for holding a disc-shaped recording medium. A rotor consists of a permanent magnet fixed to a rotating shaft that generates magnetic force in the radial direction, and multiple coils are wound around an iron core that can pass magnetic flux in the radial direction. In an electric motor equipped with a stator placed outside the rotor that generates rotational force, a part of the outer periphery of the core of the stator is recessed or cut out to the inner periphery to form a recess or open part without a coil. At the same time, a sliding member made of resin or metal with a low coefficient of friction is placed between the back surface of the holding mechanism and the end face of the bearing component, and is constantly pressed toward the bearing component by the magnetic attraction force of the permanent magnet of the rotor. It is something that has been mediated.

Further, in each of the other electric motors according to the present invention, the holding mechanism or the sliding member is provided with a structure that particularly restricts relative sliding between the sliding member and the holding mechanism.

[Function] In this invention, the stator is located on the outside,
Since a part of the stator core is retreated or opened in the radial direction, by aligning the movement line of the magnetic head with the opening of the recess in the core, the magnetic head and other members can be aligned with the rotor and stator. This allows the magnetic recording device to be made thinner, and also allows the magnetic recording device to be placed between the back of the holding mechanism provided on the rotating shaft and the end face of the bearing component made of oil-impregnated sintered metal that supports the rotating shaft. By interposing a sliding member with a low coefficient of friction that is constantly pressed against the bearing component side by the magnetic attraction force of the rotor's permanent magnets, axial runout of the rotating shaft is suppressed and vibration of the holding mechanism is also suppressed. Therefore, the recording medium can be rotated with high precision.

Further, in another aspect of the invention, since the friction between the holding mechanism and the sliding member is particularly restricted and friction in this area is suppressed, stable bearing function over a long period of time can be obtained.

[Embodiment] FIG. 1 is a sectional view of a motor showing an embodiment of the present invention, and FIG. 5 is a sectional view showing a structure in which a motor equivalent to this embodiment is applied to a magnetic recording device. In FIGS. 1 and 5, a bearing component 2 made of oil-impregnated sintered metal, etc., which rotatably supports a rotating shaft 1 in the center, is vertically mounted on a flat motor frame 4 on which a stator 3 is attached. It is fitted into a fixed holder. The stator 3 is screwed and fixed concentrically to the bearing component 2 on the motor frame 4 via a spacer 5, and a plurality of coils 6 are wound inside the iron core 3a. The coil 6 is wound around 15 consecutive core teeth obtained by dividing the inner circumference of the core 3a into 18 equal parts, and the inner diameter portion of the core 3a corresponding to three consecutive core teeth is a bridge. It is formed as a connecting portion 3b. That is, the iron core 3a
The outer periphery of the missing portion of the coil 6 is formed as a recessed portion 3c that recedes toward the inner periphery. The number of coils 6 is 3
Xm (m is a positive integer of 2 or more), and the number of missing coils is 3Xn (a positive integer of 4 or more). Inside the stator 3, there is a rotor in which a permanent magnet 9 is fixed to the outer circumferential side of a ring-shaped rotor yoke 8 made of ferromagnetic metal that is integrated into a holding mechanism 7 that is press-fitted or integrally molded into the rotating shaft 1. 10 is configured to be rotatable. The holding mechanism 7 holds a disc-shaped magnetic recording medium 11 and rotates it. Further, the permanent magnet 9 generates magnetic force in the radial direction, and faces the inner circumferential surface of the stator 3 with a predetermined gap therebetween. Between the back surface of the holding mechanism 7 and the end surface of the bearing component 2 on the holding mechanism 7 side, there is a washer-shaped sliding member 12 made of resin or metal with a low coefficient of friction.
is mediated. This sliding member 12 has a magnetic attraction force of the permanent magnet 9 of the rotor 10 applied to the holder [7].
A force of gf to 300 gf is constantly applied to the bearing component 2 side. Above the plurality of coils 6 of the stator 3, the inner circumferential edge of a shaft insertion hole that covers the end surfaces of the coils 6 and the iron core 3a on the holding mechanism side, and into which the rotating shaft 1 is loosely fitted, is permanently attached to the rotor 10. A magnetic shielding plate 13 is provided that is located closer to the rotating shaft than the maximum outer circumferential portion formed by the magnet 9 . This magnetic shielding plate 1
Reference numeral 3 indicates several mounting legs formed on the outer periphery, which are collinear with the iron core 3a by the mounting screws of the stator 3 which are screw-fixed through the spacer 5, and the magnetic head 14° 1
5 and the recording medium 11 held by the holding mechanism 7 is blocked to protect the coil 6. Note that the reference numeral 16 in the figure indicates a drive pin provided on the holding mechanism 7.

Figures 2 to 4 and Figure 5 all show other embodiments of the sliding member 12 interposed between the holding mechanism 7 and the bearing component 2, and Figure 2 is a cross section showing the electric motor. Figure, 3rd
The figure is an exploded perspective view, FIG. 4 is a perspective view of the sliding member 12 and the holding mechanism 7, and FIG. 5 is a sectional view showing a configuration in which the electric motor is applied to a magnetic recording device. The electric motor of this embodiment has a structure that prevents the sliding member 12 from rotating together with the holding machine iI7. That is, a projection 7a is formed on the back surface of the holding mechanism 7, and the projection 7a is formed on the outer periphery of the sliding member 12.
A protrusion 12a is formed to stop the hook. Of course, only the holding mechanism 7 side or only the sliding member 12 side may be provided with a structure that prevents the sliding member 12 from rotating together with the holding mechanism 7.

As a result, there is almost no friction between the holding mechanism 7 and the sliding member 12, resulting in low friction sliding between the sliding member 12 and the bearing component 2, and improved durability.

Regarding the iron core 3a, the above-mentioned conditions regarding the number of coils 6 are the same, and the iron core 3a may be formed into a substantially C-shaped planar shape by opening the portions of the iron core 3a corresponding to the missing coils.

In any of the embodiments described above, since a part of the iron core 3a is made into a recessed part 3c or an open part, a significant unbalanced force is generated in the magnetic force acting in the radial direction with respect to the permanent magnet 9 of the rotor 10. A force in a certain direction acts as a preload at all times, preventing the shaft runout of the rotating shaft 1.
As shown in the figure, a magnetic head 14.15 is installed on a support shaft fixed to the motor frame 4 via a member so as to be movable linearly by means of a sliding member 12.
By aligning the movement line of 5 with the recess 3C or open portion of the iron core 3a, the rotor 10, stator 3, and magnetic heads 14 and 15 can be arranged substantially in the same plane. Thereby, it is possible to easily achieve a thinner magnetic recording device. Furthermore, part or all of the inner peripheral edge of the magnetic shielding plate 13
Since the permanent magnet 9 is located closer to the rotation axis than the maximum outer circumference formed by the permanent magnet 9, the extraction of the rotor 10 in the axial direction l\ can be restricted by the magnetic shielding plate 13 without any special dedicated parts. , cost reduction can also be planned. And sliding member 1
2 suppresses the axial vibration of the rotating shaft 1 and also suppresses the vibration of the holding mechanism 7, so that the recording medium 11 can be rotated with high precision.

[Effects of the Invention 1] As is clear from the above description of the embodiments, according to the present invention, the stator is located on the outside and a part of the iron core of the stator is retreated or opened in the radial direction. By aligning the movement line of the magnetic head with the recess or open portion of the core, members such as the magnetic head can be housed within the plane of the rotor and stator, making it possible to make the magnetic recording device thinner. In addition, between the back surface of the holding mechanism provided on the rotating shaft and the end face of the bearing component made of oil-impregnated sintered metal, etc. that supports the rotating shaft, a permanent magnet of the rotor is made of resin or metal with a low coefficient of friction. By interposing a sliding member that is constantly pressed against the bearing component side by the magnetic attraction force, the vibration of the rotating shaft is suppressed, and the vibration of the holding mechanism is also suppressed, making it possible to rotate the recording medium with high precision. You can get the desired effect.

Further, according to another invention, rubbing between the holding mechanism and the sliding member is particularly restricted, and stable bearing function over a long period of time can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an electric motor as an embodiment of the present invention, FIG. 2 is a sectional view showing an electric motor as another embodiment of the invention, FIG. 3 is an exploded perspective view thereof, and FIG. 5 is a perspective view showing the relationship between the holding mechanism and the sliding member, and FIG. 5 is a sectional view showing the configuration in which the electric motor is applied to a magnetic recording device.
FIG. 6 is a sectional view of a conventional electric motor, and FIG. 7 is a front view of a magnetic recording device using a conventional electric motor. In the figure, 1 is a rotating shaft, 3 is a stator, 3a is an iron core, 3
C is a recess, 6 is a coil, 7 is a holding mechanism, 7a is a protrusion, 9
10 is a permanent magnet, 10 is a rotor, 11 is a recording medium, 12 is a sliding member, and 12a is a protrusion. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent: Masuo Oiwa (and 2 others) Procedural amendment (voluntary) Relationship with the April 10, 1995 Electric Motor 3 case and the person making the amendment Patent applicant address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name Title (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4, Agent Address 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo, Detailed description of the invention in the specification to be amended. 6. From the first line of page 4 of the statement of contents of the amendment to the second line of the same page, “
The description of ``index detection element 27'' of the index detection magnet 28 is corrected to ``magnetic detection element (not shown).''that's all

Claims (3)

[Claims] (1) A permanent magnet that is rotatably held perpendicular to the frame by bearing parts such as oil-impregnated sintered metal and that generates magnetic force in the radial direction on a rotating shaft that is equipped with a holding mechanism that holds a disc-shaped recording medium. A rotor is fixed to the rotor, and a plurality of coils are wound around an iron core through which magnetic flux can pass in the radial direction, and the outside of the rotor generates a rotational force in the rotor through magnetic interaction with the permanent magnet. In the electric motor, a part of the outer periphery of the iron core of the stator is set back or cut inward to form a recessed part or an open part without a coil, and the above-mentioned holding part is A sliding member is interposed between the back surface of the mechanism and the end face of the bearing component, which is made of resin or metal with a low friction coefficient and is constantly pressed toward the bearing component by the magnetic attraction force of the permanent magnet of the rotor. An electric motor featuring: (2) The electric motor according to claim 1, wherein the holding mechanism is provided with a structure that restricts relative sliding between the sliding member and the holding mechanism. (3) The electric motor according to claim 1, wherein the sliding member is provided with a structure that restricts relative sliding between the sliding member and the holding mechanism.