JP2001314061A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor wherein preloading can be applied even if the magnetic centers of the stator and the rotor magnetic substantially match each other, vibration of the rotor holder is suppressed for the enhancement of motor characteristics, and the dimensions in the axial direction are reduced. SOLUTION: The motor comprises a rotating shaft 4 rotatably held by radial sliding bearings 3 and a thrust plate 8 for supporting the shaft end, a cup-shaped rotor holder 5 fixed to the rotating shaft 4, and a stationary portion 11 having a boss portion 2 into which the rotating shaft 4 is inserted through the radial sliding bearings 3 and a stator 7. In addition, the motor is provided between the inner surface of the top wall portion 5a of the cup-shaped rotor holder 5 and the stationary portion 11 with a preload applying means 20 that produces suction force in the direction of thrust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a motor using a sliding bearing.

[0002]

2. Description of the Related Art Generally, a motor is mounted on a base plate 40, as shown in FIG.
The rotating shaft 43 is supported on cylindrical bosses (bearing housings) 41 mounted on the shaft via sliding bearings 42, 42 made of sintered oil-impregnated bearings, and a bowl-shaped rotor holder 44 is fixed to the rotating shaft 43, An annular rotor magnet 45 is provided on the inner surface of the outer peripheral wall of the mold rotor holder 44, and a stator 46 is fitted and fixed to the outer peripheral surface of the boss 41 so as to face the rotor magnet 45 in the radial direction.

The rotary shaft 43 is supported by bearings 42, 42 in the radial direction (radial direction), and the lower opening of the boss 41 in the axial direction (thrust direction).
The lower end of the rotary shaft 43 is supported on a thrust plate 47 provided so as to close the 41a by contacting the lower end of the rotary shaft 43 via a bush 48.

Conventionally, the magnetic centers of the stator 46 and the rotor magnet 45 are shifted by a predetermined distance ε in the axial direction, so that the bowl-shaped rotor holder 44 including the rotating shaft 43 is moved to the thrust plate 47 side (in the direction of arrow A). ) (By applying a preload) so that it can be stably supported in the axial direction.

[0005]

However, since the axial preload of the bowl-shaped rotor holder 44 depends only on the displacement of the magnetic center between the stator 46 and the rotor magnet 45, the bowl-shaped rotor holder 44 may vibrate. There is. This is because magnetic attraction and repulsion are repeated between the rotor magnet 45 and the stator 46. Also, depending on the structure and application of the motor, a large preload may be required. In such a case, it is necessary to set a large predetermined distance ε for deviation, and the motor characteristics (bowl-shaped rotor holder)
44) and the size of the motor in the axial direction may increase. Further, since the magnetic center between the stator 46 and the rotor magnet 45 must be intentionally shifted by a predetermined distance, precision is required at the time of assembling, and there is a difficulty in assembling.

Accordingly, the present invention provides a preload in the thrust direction even when the magnetic centers of the stator and the rotor magnet are substantially coincident with each other, suppresses vibration of the bowl-shaped rotor holder, improves motor characteristics, and improves shaft characteristics. It is an object of the present invention to provide a motor whose dimension in the center direction is suppressed.

[0007]

In order to achieve the above-mentioned object, a motor according to the present invention comprises: a rotary shaft rotatably held by a radial slide bearing and a shaft end supporting thrust plate; An inner surface of a top wall portion of the bowl-shaped rotor holder in a motor including a fixed bowl-shaped rotor holder, and a stationary portion having a boss portion and a stator into which the rotating shaft is inserted via the radial slide bearing. And a preload applying means for generating a suction force in the thrust direction between the stationary part and the stationary part.

[0008] With this configuration, even when the magnetic centers of the stator and the rotor magnet are substantially aligned, a preload in the thrust direction can be applied, vibration of the bowl-shaped rotor holder is suppressed, and motor characteristics are improved. Further, the dimension in the thrust direction (axial direction) can be suppressed. Further, since it is not necessary to intentionally shift the magnetic center between the stator and the rotor magnet by a predetermined distance, high accuracy is not required at the time of assembling, and the assembling can be easily performed.

[0009] The preload applying means includes a preload magnet. Therefore, a simple structure can be obtained, and a preload can be reliably applied.

The preload applying means comprises a preload magnet provided on a boss portion of the stationary portion, and the top wall portion made of a magnetic material. Therefore,
It is possible to prevent the magnetic flux of the preload magnet from flowing into the stator. Further, the preload can be reliably applied to the bowl-shaped rotor holder.

Further, the stator core of the stator constituting the stationary portion is an annealed core. Therefore, since the magnetic resistance of the stator core is reduced, the current value to the stator (coil) required for obtaining the required magnetic characteristics can be reduced.

Further, the preload magnet is an annular magnet multipolarly magnetized in a circumferential direction. Therefore, the magnetic flux from the preload magnet does not spread so much, and the influence on the stator is greatly reduced, and the current value to the stator (coil) necessary for obtaining the required magnetic characteristics can be further reduced. In addition, cogging torque (rotational unevenness) can be reduced.

[0013] Further, the preload magnet is disposed in the stationary portion via a shielding member. Therefore,
The magnetic force (magnetic flux) of the preload magnet is prevented from flowing into the stator, and the influence on the electric characteristics of the motor is reduced. Accordingly, it is not necessary to weaken the magnetic force of the preload magnet, and the preload can be more reliably applied to the bowl-shaped rotor holder.

In the bowl-shaped rotor holder, a clamp magnet for clamping the recording disk is disposed on an outer surface of a top wall portion facing the recording disk to be mounted. Accordingly, it is possible to prevent the recording disk from spinning and to reliably hold the recording disk.

The preload applying means includes a preload magnet, and the preload magnet is disposed on an inner surface of a top wall of the bowl-shaped rotor holder, and the preload magnet and the clamp magnet are integrally formed. It is a thing. Therefore, the number of parts can be reduced and the number of assembling steps can be simplified.

Further, the preload magnet and the clamp magnet are formed by injection molding.
Therefore, it can be easily formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments.

FIG. 1 is a side sectional view showing a DC (brushless) motor as an embodiment of the motor of the present invention. This motor has a pair of cylindrical radial sliding bearings 3 composed of sintered oil-impregnated sliding bearings. And a rotating shaft 4 rotatably held by a shaft end supporting thrust plate 8;
It comprises a bowl-shaped rotor holder 5 fixed to the rotating shaft 4 and a stationary portion 11 having a boss 2 into which the rotating shaft 4 is inserted and a stator 7. The rotary shaft 4 is inserted into the boss portion 2 of the stationary portion 11 via the radial slide bearings 3, 3.

More specifically, the stationary part 11 includes a base plate 1, a cylindrical boss (bearing housing) 2 attached to the base plate 1, and a stator 7 fitted and fixed to the outer peripheral surface of the boss 2. , Have. The stator 7 includes a stator core 9 fixed to the boss 2 and a coil 10 wound around the stator core 9.

The bowl-shaped rotor holder 5 is made of metal (magnetic material)
A top wall portion (annular plate portion) 5a at the center of which the rotary shaft 4 penetrates and is fixed, and an outer peripheral wall portion 5b hung on the outer peripheral surface of the top wall portion 5a. On the inside,
The annular rotor magnet 6 is disposed so as to face the stator 7 in the radial direction.

The rotary shaft 4 is supported by radial sliding bearings 3 and 3 in the radial direction (radial direction), and has the lower opening 2a of the boss 2 in the axial direction (thrust direction). The lower end of the rotary shaft 4 is connected to a thrust plate 8 for supporting the shaft end provided so as to be closed.
It is supported by abutment via 18.

The top wall 5a of the bowl-shaped rotor holder 5
A preload applying means 20 for generating a suction force in the thrust direction is provided between the inner surface of the base member and the stationary portion 11. More specifically, the preload applying means 20 includes a preload magnet 12 provided on the boss portion 2 of the stationary portion 11 and a top wall portion 5a made of a magnetic material. A preload is applied in the direction and on the stationary portion 11 side. Therefore, the bowl-shaped rotor holder 5 including the rotating shaft 4 is urged toward the thrust plate 8 (in the direction of the arrow A) (preload is applied) so that it can be stably supported in the axial direction.

The preload magnet 12 is, as shown in FIG.
It is formed in a ring shape and is multipolarly magnetized in the circumferential direction. As shown in FIG. 1, it is mounted on the upper surface of the boss portion 2 and acts on the top wall portion 5 a of the bowl-shaped rotor holder 5 to exert a magnetic attraction force. Let it. Here, in the case of a single-pole magnetized preload magnet, the magnetic loop greatly spreads around the outer periphery of the magnet, and the influence on the stator 7 is increased. However, as described above, the preload magnet 12 Since the magnetic loop from the coil is suppressed to a small extent and the influence on the stator 7 can be reduced, the current value to the stator 7 (coil 10) required to obtain the required magnetic characteristics can be reduced. This magnetic field is not affected by other magnetic fields, so that no magnetic imbalance occurs and cogging torque (rotational unevenness) can be reduced.

The magnetic center of the stator 7 and the magnetic center of the rotor magnet 6 are made substantially coincident with each other, so that the displacement of the magnetic center (a predetermined distance ε in FIG. 7) as in the prior art is eliminated, and the vibration of the bowl-shaped rotor holder 5 is suppressed. Thus, the motor characteristics can be improved. Further, the dimension of the motor in the axial direction can be suppressed.

It is desirable that the stator core 9 be an annealed core, so that the current value to the stator 7 (coil 10) can be further reduced.

Next, FIG. 3 shows another embodiment of the present motor, in which a preload magnet 12 is disposed on a stationary portion 11 via a shielding member 13. More specifically, a flat annular shielding member 13 (which is a non-magnetic material such as permalloy) is attached (attached) to the upper surface of the boss 2 and the upper surface of the stator core 9, and the preload magnet 12 is attached to the shielding member 13. Mounted on the top.

Therefore, the shielding member 13 blocks the magnetic force of the preload magnet 12, prevents the magnetic flux of the preload magnet 12 from flowing into the stator 7, and reduces the influence on the magnetic characteristics of the motor. Further, it is not necessary to weaken the magnetic force of the preload magnet 12 in consideration of the influence on the stator 7,
Preload can be more reliably applied to the bowl-shaped rotor holder 5 (applying a suction force in the axial direction). Further, there is no need to change the number of poles of the preload magnet 12, and it is possible to reduce the current value and the cogging torque, as described above, without any trouble. In short, the influence on the motor characteristics can be reduced while maintaining the magnetic attraction.

As shown in FIG. 4, the shielding member 13 is
The outer peripheral surface of the preload magnet 12 may be covered, so that leakage of magnetic flux from the outer peripheral surface of the preload magnet 12 can be blocked, and the magnetic flux of the preload magnet 12 can be reliably prevented from flowing into the stator 7. As described above, adjustment can be performed by changing the shape of the shielding member 13.

Next, FIG. 5 shows another embodiment of the present motor, in which a bowl-shaped rotor holder 5 is mounted (high capacity F
A clamp magnet 15 for clamping the recording disk 14 is provided on the outer surface (upper surface) of the top wall 5a facing the recording disk 14 (D, optical disk, etc.).

More specifically, the bowl-shaped rotor holder 5
Has a protruding receiving portion 22 for receiving the recording disk 14,
Further, the clamp magnet 15 faces the metal portion 16 near the center of the recording disk 14.

As described above, the clamp magnet 15 is disposed so as to face the metal portion 16, and the metal portion 16 can be clamped by applying a magnetic attraction (in the axial direction). As a result, idling of the recording disk 14 can be prevented and the recording disk 14 can be reliably held.

Next, FIG. 6 shows still another embodiment of the present motor. Compared with FIG. 5, the following configuration is obviously different. That is, the preload magnet 12 and the clamp magnet 15 are formed integrally.

Specifically, the preload magnet 12 is
The bowl-shaped rotor holder 5 is provided on the inner surface (lower surface) of the top wall portion 5 a and is formed integrally with the clamp magnet 15. This is because a plurality of holes 17 are provided in the circumferential direction in the vicinity of the center of the top wall portion 5a, and the preloaded magnet 12 and the clamp magnet 15 are injection molded by pouring the melted magnet by injection. By integral molding.

In this case, the preload magnet 12 is
A magnetic attraction force is applied to the boss portion 2 (made of a magnetic material), and as a result, a preload in the axial direction is applied to the bowl-shaped rotor holder 5.

Therefore, by integrally molding (commonizing) the preload magnet 12 and the clamp magnet 15, the number of parts can be reduced and the number of assembling steps can be simplified. The magnet used for injection molding is
Although it was difficult to use many ferrites and low magnetic force, high-performance materials have recently been developed for injection and are effective.

In the above-described embodiments shown in FIGS. 1 to 6, the rotor magnet 6 has a so-called outer rotor type structure in which the rotor magnet 6 is disposed on the outer peripheral side of the stator 7. It is also possible to adopt a so-called inner rotor type structure which is arranged on the peripheral side, or a so-called axial gap type structure in which the rotor magnet 6 is arranged to face the axial direction of the stator 7.

The present invention is not limited to the above-described embodiment, and a plurality of preload magnets 12 may be provided as single-pole magnetized magnets to reduce the cost. Further, a shielding member 13 may be attached to the preload magnet 12 shown in FIG. 5 to prevent leakage of magnetic force. Further, the preload magnet 12 may be provided on the stator core 9, and the design can be changed without departing from the gist of the present invention.

[0038]

According to the present invention, even when the magnetic centers of the stator 7 and the rotor magnet 6 are substantially aligned in the axial direction, the preload in the thrust direction can be applied, and the vibration of the bowl-shaped rotor holder 5 can be suppressed. , Improve motor characteristics, and
The dimension in the axial direction can be suppressed. Also, since no accuracy is required in assembling, the assembling can be easily performed.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of a preload magnet.

FIG. 3 is a side sectional view showing another embodiment of the present invention.

FIG. 4 is a side sectional view showing still another embodiment of the present invention.

FIG. 5 is a side sectional view showing another embodiment of the present invention.

FIG. 6 is a side sectional view showing still another embodiment of the present invention.

FIG. 7 is a side sectional view showing a conventional example.

[Explanation of symbols]

 2 Boss part 3 Radial sliding bearing 4 Rotary shaft 5 Bowl-shaped rotor holder 5a Top wall part 7 Stator 8 Shaft end supporting thrust plate 9 Stator core 11 Stationary part 12 Preload magnet 13 Shielding member 14 Recording disk 15 Clamp magnet 20 Preload applying means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shoji Hishinuma 248 Nakajuku, Aichigawa-machi, Aichi-gun, Aichi-gun, Shiga F-term in Nidec Shiga R & D Center (Reference) 5H605 AA05 BB05 CC02 CC03 DD05 EA03 EB39

Claims (9)

[Claims] A rotary shaft rotatably held by a radial slide bearing and a shaft end supporting thrust plate; a bowl-shaped rotor holder fixed to the rotary shaft;
In a motor including a boss portion into which the rotating shaft is inserted via the radial slide bearing and a stationary portion having a stator, the motor includes a stationary portion having a top wall portion of the bowl-shaped rotor holder and the stationary portion. A motor provided with a preload applying means for generating a suction force in a thrust direction. 2. The motor according to claim 1, wherein said preload applying means includes a preload magnet. 3. The motor according to claim 1, wherein said preload applying means comprises a preload magnet provided on a boss portion of said stationary portion, and said top wall portion made of a magnetic material. 4. The motor according to claim 1, wherein the stator core of the stator constituting the stationary portion is an annealed core. 5. The motor according to claim 2, wherein the preload magnet is an annular magnet multipolarly magnetized in a circumferential direction. 6. The motor according to claim 2, wherein said preload magnet is disposed on said stationary portion via a shielding member. 7. The motor according to claim 1, wherein the bowl-shaped rotor holder is provided with a clamp magnet for clamping the recording disk on an outer surface of a top wall portion facing the recording disk to be mounted. 8. The preload applying means includes a preload magnet, and the preload magnet is disposed on an inner surface of a top wall of the bowl-shaped rotor holder, and the preload magnet and the clamp magnet are formed integrally. The motor of claim 7. 9. The motor according to claim 8, wherein said preload magnet and said clamp magnet are formed by injection molding.