JPH09103043A - Motor with sleeve bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a thrust member from being deformed and destroyed against vibration by forming a groove in the axial direction of the inner periphery of a sleeve bearing, and filling a groove with grease. SOLUTION: At the outer periphery of a sleeve bearing 22, six grooves (grease retaining groove) 22a are formed along the thrust direction (axial direction). If the groove 22a is filled with grease 32, grease 32 is attracted in the bearing from the groove 22a by negative pressure created in the sleeve bearing 22 when the shaft 28 of a rotor moves in such a direction as it gets out of the sleeve bearing 22 together with the vibration of an apparatus equipped with a motor, and goes out in a space between the shaft 28 and a thrust part 24. Grease 32 serves as a buffering member even if the direction of the vibration alternates and acceleration is applied downwards by the rotor, therefore, the impact generated by a contact with the thrust member 24 is relieved. It is thus possible to prevent the thrust member from being deformed and destroyed due to the vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a motor equipped with a sleeve bearing suitable for, for example, a flexible disk drive or a CD-ROM spindle motor, and is provided with a sleeve bearing that is resistant to vibration and can be used at high temperatures. Motors.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional motor having a sleeve bearing, which is a flat motor base 1 made of a metal plate.
A thrust member holding portion 1a for holding the thrust member 2 is formed on the inside by press drawing or the like. The armature core 4 provided with the armature winding 3 is integrally fixed to the motor base 1 by screws 6 via a bearing holder 5 on the motor base 1. The sleeve bearing 7 is press-fitted and fixed to the inner circumference of the bearing holder 5.

A cup-shaped rotor yoke 9 in which a shaft 8 is fitted in a sleeve bearing 7 has a drive magnet 1 on its inner circumference.
No. 0 is fixed, and a drive pole of 16 poles is magnetized on the inner peripheral surface of the drive magnet 10 facing the outer periphery of the armature iron core 4 with a slight gap, and the printed circuit board 11 on the motor base 1 is magnetized. FG magnetic poles of 120 poles are magnetized on the end faces facing each other with a slight gap therebetween. The armature core 4 is provided with a three-phase armature winding 3 with 12 slots, and is energized and driven by a rotor position detection means and a brushless motor drive circuit (not shown) to generate a field magnetic field and rotate the drive magnet 10. Generate the driving force. An FG is formed on a portion of the printed circuit board 11 facing the drive magnet 10.
A repetitive pattern coil for power generation is formed, and this FG pattern coil generates and outputs a signal whose frequency is proportional to the rotation speed of the rotor. The rotation speed of the motor is kept constant by being configured to control the drive current of the armature winding according to the frequency of the power generation output signal,
Perform the intended function.

[0004]

By the way, the conventional motor having the sleeve bearing described above has the following problems.

The first problem is that the rotor moves up and down mainly in the thrust direction along with the vibration of the equipment to which the motor is attached. When upward vibration acceleration is applied to the rotor, the rotor and the shaft 8 move together with the rotor 8 in a direction away from the sleeve bearing 7. At this time, the sleeve bearing 7 and the shaft 8 act like a cylinder and a piston, and as the upward movement amount of the shaft 8 increases, a negative pressure is generated in the sleeve bearing 7 and a force for sucking the shaft 8 downward is generated. Become.

Here, when the vibration direction alternates and a downward acceleration is applied to the rotor, a combined force of the suction force due to the negative pressure acts on the shaft 8 and the shaft 8 is rapidly accelerated downward and collides with the thrust member 2. . According to the experiment, it was found that when the device equipped with the motor is subjected to normal-use vibration, the thrust member 2 is repeatedly subjected to a shock of 200 G at peak time,
This phenomenon causes deformation or destruction of the thrust member 2 and shortens the rotational life of the motor.

Next, the second problem will be described. Generally, in order to prolong the rotational life of the sleeve bearing, the sleeve bearing is used by impregnating a porous sintered metal with lubricating oil. The sleeve bearing and the shaft made of sintered metal have a pumping action, and as the shaft 8 rotates, the lubricating oil leaks into the gap between the inner periphery of the bearing 7 and the outer periphery of the shaft 8 to provide a lubricating action.
However, when rotating for a long time, this lubricating oil oozes out from the boundary surface between the sleeve bearing 7 and the shaft 8. The lubricating oil that oozes out is retained by surface tension, and the portion in contact with the surface of the bearing is taken into the bearing by the pump action and circulates, but in this example, the amount that can be retained in the portion indicated by the arrow in FIG. 6 is small, There is a phenomenon that many parts are transmitted along the surface of the shaft and flow out.

On the other hand, as the density of equipment incorporating a motor increases, the temperature rise inside the equipment during use becomes large, and the temperature rises easily.
It is predicted that the temperature will rise to 0 ° C or higher, but this lubricating oil outflow phenomenon becomes noticeable due to the decrease in the viscosity of the lubricating oil when the temperature rises to around 80 ° C, and oil shortage easily occurs, resulting in an extremely short rotation life. There is. In addition, the lubricating oil that leaks may contaminate the equipment or cause a malfunction.

The present invention has been made in view of these problems, and provides a motor provided with a sleeve bearing in which the thrust member is not deformed and broken by vibration and has a long life, and the life is not shortened due to the outflow of lubricating oil. Is.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first invention is to dispose an armature core having an armature winding on a motor base, a sleeve bearing and a thrust member. And a sleeve bearing provided with a rotatable magnet having a shaft fitted to the sleeve bearing, the rotor yoke having a drive magnet having a drive magnetic pole facing the armature core through a predetermined gap. Also provided is a motor having a sleeve bearing, characterized in that a groove is provided in an inner peripheral direction of the sleeve bearing and the groove is filled with grease.

According to a second aspect of the invention, an armature coil, a sleeve bearing, and a thrust member are arranged on a motor base, a shaft is inserted into the sleeve bearing and rotatably supported, and a rotor yoke is fixed to the shaft. In the motor having a sleeve bearing in which the rotor yoke is provided with a drive magnet having a drive magnetic pole on a surface facing the armature coil with a slight gap, the motor is provided with a shaft end of the shaft of the sleeve bearing. The present invention provides a motor having a sleeve bearing, which is characterized in that a lubricating oil holding groove is provided at a boundary portion of each.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a motor having a sleeve bearing according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a sectional view of an embodiment of a motor provided with a sleeve bearing of the present invention.

The motor base 20 made of a metal plate is integrally formed by press drawing and the like.
1. A protruding disk-shaped iron core fitting portion 20a for fitting and positioning the inner periphery of the iron core 1 so as to be mounted, and this iron core fitting portion 20a.
A cylindrical bearing fitting portion 20b that is connected to one side of the sleeve bearing 22 to fit the outer circumference of the sleeve bearing 22 to hold the bearing 22, and a metal printed circuit board 23 that is connected to the other of the iron core fitting portion 20a. And a printed circuit board fitting portion 20c for fitting the inner circumference of the printed circuit board 23 to position the printed circuit board 23.

The armature iron core 21 is fitted to the other side of the printed board fitting portion 20c and the thrust holder 25 for holding the thrust member 24 together with a screw 26 on the iron core fitting portion 20a which serves as a pedestal of the motor base 20. It is fixed at.

The armature core 21 has 12 slots and three-phase armature windings 27 as in the conventional case.

A drive magnet 30 is fixed to the inner periphery of a cup-shaped rotor yoke 29 in which the shaft 28 is fitted in the sleeve bearing 22, and a slight gap is provided between the drive magnet 30 and the outer periphery of the armature core 21. 16 poles of the drive magnetic poles are magnetized on the inner peripheral surfaces facing each other, and 120 poles of the FG magnetic poles are magnetized on the end surface facing the printed circuit board 23 positioned on the motor base 20 with a slight gap. Has been done. Further, a notch is provided in a part of the bottom surface of the sleeve bearing 22, and a rubber O-ring 31 is sandwiched between the sleeve bearing 22 and the thrust member 25 to improve airtightness.

The rotor position detecting means (not shown) and a brushless motor drive circuit are energized to generate a field magnetic field, which causes the drive magnet 30 to generate a rotational drive force. A repeating pattern coil for FG power generation is formed in a portion of the printed circuit board 23 facing the drive magnet 30, and this FG pattern coil generates and outputs a signal whose frequency is proportional to the rotation speed of the rotor. By configuring so as to control the drive current of the armature winding according to the frequency of the power generation output signal, the rotation speed of the motor is kept constant and the desired function is achieved.

As described above, since the main parts such as the armature core 21, the sleeve bearing 22 and the printed circuit board 23 on which the FG pattern coil is arranged are positioned concentrically on the motor base 20, each part is highly accurate. Can be assembled.
Therefore, the deflection of the outer periphery of the armature core 21 with respect to the shaft rotation center and the deflection of the inner periphery of the drive magnet 30 are both improved, and the gap between them can be designed small, and the torque is increased. Similarly, since the printed circuit board is also assembled so as to be directly fitted to the motor base, the fluctuation of the FG pattern is small and the frequency fluctuation of the output FG signal is small, and the uneven rotation is small.

The functions of the groove and the grease filled in the groove will be described below. As shown in FIG. 2, six grooves (grease holding grooves) 22a are formed on the inner circumference of the sleeve bearing 22 along the thrust direction (axial direction). If this groove 22 is filled with grease, the rotor shaft 2 will be vibrated along with the vibration of the equipment in which the motor is mounted.
When 8 moves in the direction of coming out of the sleeve bearing 22,
Due to the negative pressure generated in the sleeve bearing 22, FIG.
As shown in FIG. 5, the grease 31 is sucked into the bearing from the groove 22a and comes out in the space between the shaft 28 and the thrust member 24. Here, even if the direction of vibration alternates and the rotor is accelerated downward, as shown in FIG. 3C, since the grease 32 acts as a cushioning material, the impact upon contact with the thrust member 24 is alleviated. According to the experiment, when the device equipped with the motor is subjected to normal use vibration, the thrust member 24 is relaxed to an impact of about 30 G even at the peak time, and the thrust member 24 is not deformed by such an impact. There was found. Further, in the experiment, when the shaft diameter is 3 to 6 mm, the width of the groove is about 0.5 to 1 mm, but the depth of the groove is 30.
Approximately 150 μm, and the number of approximately 4 to 12 exhibited a preferable effect.

As described above, according to the present invention, there is an effect that the impact applied to the thrust receiving member due to the vibration is mitigated, its deformation is prevented, and the rotation life of the motor is extended.

Further, the function of the sleeve bearing 22 having the lubricating oil holding groove 22b at the boundary portion with the shaft end of the shaft 28 of the sleeve bearing 24 described in claim 2 will be described. The holding groove is circumferentially formed with a width of 0.3 mm and a depth of 0.3 mm at the boundary between the sleeve bearing 22 and the shaft 28. Even if the lubricating oil oozes out from the boundary surface between the sleeve bearing and the shaft for a long time, the lubricating oil is retained by the surface tension in the retaining groove as shown in FIG. 4 (A), and its amount is about five times that of FIG. 6 shown in the conventional example. . Since the lubricating oil attached to the outer circumference of the sleeve bearing 22 made of sintered metal is taken inside by this pump action, the lubricating oil held in the holding groove is also taken inside and circulates. FIG. 7 shows the results of a comparative experiment of the structure of the boundary between the bearing and the shaft and the outflow rate. With the structure of this embodiment, 100 H at 80 ° C. is about 1/10 of that of the conventional example.

Further, as shown in FIG. 4 (B), if the lubricating oil holding groove 22b is formed with the groove overhanging portion 22b1, the oil retaining effect is further enhanced.

[0024]

The motor equipped with the sleeve bearing according to the present invention, which has been described in detail above, has the effect of reducing the outflow of lubricating oil at high temperatures and prolonging the rotational life. Also, the outflow of lubricating oil is prevented from contaminating the equipment.

Furthermore, since the main parts such as the armature core, the sleeve bearing, and the printed circuit board are positioned on the motor base, the parts are assembled with high accuracy and the runout of the armature core around the shaft rotation center is eliminated. And the deflection of the inner circumference of the drive magnet are both improved, and the gap between them can be designed to be small, which has the effect of increasing the torque.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a motor having a sleeve bearing of the present invention.

FIG. 2 is an explanatory diagram of a sleeve bearing.

FIG. 3 is an operation explanatory view showing the relationship between the sleeve bearing and the shaft.

FIG. 4 is a partial enlarged view of a sleeve bearing and a shaft end portion showing another embodiment of the present invention.

FIG. 5 is a sectional view of a motor having a conventional sleeve bearing.

6 is a partially enlarged view of a sleeve bearing and a shaft end portion in FIG.

FIG. 7 is a comparative graph of the amount of lubricating oil outflow.

[Explanation of symbols]

20 ... Motor base, 21 ... Armature core, 22 ... Sleeve bearing, 22a ... Groove, 23 ... Printed circuit board, 30 ... Drive magnet, 32 ... Grease.

[Procedure amendment]

[Submission date] January 30, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Motor having a sleeve bearing

Claims (5)

[Claims] 1. A motor base is provided with an armature core having an armature winding, a sleeve bearing and a thrust member, and a rotatable rotor yoke having a shaft fitted to the sleeve bearing is provided. A motor provided with a sleeve bearing provided with a drive magnet having a drive magnetic pole facing the armature core through a predetermined gap, wherein a groove is provided in an axial direction of an inner circumference of the sleeve bearing, and the groove is filled with grease. A motor provided with a sleeve bearing characterized in that 2. An armature coil, a sleeve bearing and a thrust member are arranged on a motor base, a shaft is inserted into the sleeve bearing and rotatably supported, and a rotor yoke is fixed to the shaft and the rotor yoke is fixed to the rotor yoke. In a motor having a sleeve bearing provided with a drive magnet having a drive magnetic pole on a surface facing the armature coil with a slight gap, a lubricating oil is provided at a boundary portion between the sleeve bearing and the shaft end of the shaft. A motor provided with a sleeve bearing, which is provided with a holding groove. 3. The motor base is provided with a protruding iron core fitting portion that fits and positions on the inner circumference of the armature iron core so that the armature iron core is placed on the motor base. A bearing fitting portion that fits on the outer circumference of the bearing to hold the bearing, and a printed circuit board that is connected to the other of the iron core fitting portions and that fits on the inner circumference of the printed board to position the printed board. 3. The fitting part is integrally formed with the fitting part.
A motor provided with the sleeve bearing described. 4. A motor having a sleeve bearing according to claim 3, wherein the motor base is formed by press molding. 5. A motor having a sleeve bearing according to claim 4, wherein a repeating pattern coil for FG power generation is formed on the printed circuit board facing the driving magnet surface.