JP3060826B2 - Motor bearing structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a motor, and more particularly to a bearing structure capable of preventing shaft run-out of a motor and shaft slippage due to movement of the shaft in a thrust direction.

[0002]

2. Description of the Related Art Generally, when a shaft supported by a journal bearing is rotated, besides whirling due to unbalance of the shaft, whirling of the shaft is caused by the action of an oil film of lubricating oil between the shaft and the bearing surface. The phenomenon occurs. This phenomenon is called the Whirl phenomenon, and can lead to the destruction of the bearing and, in some cases, the entire system.In particular, in the development of high-speed, high-performance rotary motors, it is extremely important to devise ways to reduce the occurrence. It is an issue.

FIG. 7 shows a journal bearing 100 having the most general structure of a bearing, in which a bearing portion 101 has a smooth cylindrical donut shape. The most basic smooth cylindrical journal bearing 100 has a whirling phenomenon accompanied by revolution of the rotating shaft when the rotating shaft rotates, but is the most unstable bearing with respect to the whirl.

As a typical measure for suppressing the occurrence of the whirl phenomenon, the shape of the bearing surface is changed from a smooth surface to a grooved surface to give a change, and the centrifugal force due to the turning motion applied to the shaft is reduced to suppress the whirl phenomenon. There are times when you do.

FIG. 8 shows a bearing 200 in which measures are taken to prevent the occurrence of the whirl phenomenon. The bearing 200 includes a bearing 201
Grooves 202 _{1-202 4} of the inner circumferential surface 4 spaced along the entire length in the circumferential direction of the for preventing whirl is formed.

[0006]

As shown in FIG. 9, when one end of a bearing portion 101 of a bearing 100 having a structure shown in FIG. 7 is closed with a closing member 102 such as a mold, the bearing 100 is used. In this case, a space A is formed between the circular end of the shaft 110 inserted into the bearing 101 and the closing member. A minute clearance exists between the linear portion a of the shaft 110 and the bearing portion 101, but in actual use, this clearance contains lubricating oil,
The clearance is blocked by the oil film,
When the space A at the end and the outside of the bearing 100 are disconnected from each other, the space A forms a closed space. The presence of the closed space A is such that when a force acts on the shaft 110 in the direction of arrow X, that is, when a force acts in a direction in which the shaft 110 comes off the bearing 100, a force acts in a direction to suppress the force. When a force in the direction opposite to the arrow X acts on the shaft 110, the sealed space A functions as a damper. Therefore, the presence of the closed space A has a function of suppressing the shaft from moving in the thrust direction.

On the other hand, in the case of the grooved bearing portion 200 for preventing whirling shown in FIG. 8, as shown in FIG.
The presence of a groove formed 202 _{1-202 4} to the bearing portion 201, the lower portion of the space A is in communication with the outside of the bearing 200, the lower space A is not a closed space. Therefore, in this case, even if a force acts on the shaft 110 in a direction in which the shaft is pulled out, no force is generated in a direction to suppress the force, and no damper effect is generated.

The present invention has been made in view of the above problems, and is intended to compensate for the disadvantages of a bearing structure having a smooth circular bearing surface and the disadvantages of a bearing structure having a grooved bearing surface. In a plain bearing that supports the spindle shaft of a motor, it is possible to prevent the occurrence of shaft runout due to the whirl phenomenon and to apply a force in the direction to suppress the thrust force when the spindle shaft is applied. The present invention provides a bearing structure that can be used.

[0009]

SUMMARY OF THE INVENTION A bearing structure for a motor according to the present invention has a magnet mounted and a magnetic disk.
A spindle shaft for supporting the rotor projection is provided to engage with the engagement holes of the click, and pivotally supports the spindle shaft, the coil
And a bearing structure of a magnetic disk motor comprising a stator portion provided with a sliding bearing fixed to a substrate to which a core is fixed , wherein the sliding bearing is provided on a side opposite to a side supporting the rotor. An end is sealed, and a space formed by the end of the spindle shaft and the slide bearing communicates with the outside of the slide bearing on the inner peripheral surface of the bearing portion of the slide bearing or the outer peripheral surface of the spindle bearing. It is characterized in that a groove is formed so as not to occur.

[0010]

According to the present invention, a groove for preventing whirl is formed on the bearing surface of a sliding bearing in which whirl is likely to occur to prevent shaft runout due to whirl. The space between the bearing and the end of the spindle shaft does not communicate with the outside of the bearing, and the space at the end can be kept in a closed space. Accordingly, when a force acts on the spindle shaft of the motor in a direction in which the shaft comes off, a force in a direction to suppress the force can be generated, and the shaft of the motor can be prevented from coming off.

[0011]

FIG. 1 shows a bearing structure of a motor according to an embodiment of the present invention. The bearing structure of the motor of the present invention is applied to a magnetic disk drive motor mounted on a magnetic disk drive. An example is shown.

The motor 1 comprises a rotor 2 having a bearing 2 made of sintered metal fixed on a substrate 11, a spindle shaft 3 supported by the bearing 2, and a magnet 4 fixedly supported on the spindle shaft 3. And a stator portion 8 including a core 6 and a coil 7 fixed on a substrate 11. The protrusion 9 provided on the rotor 5 is a drive protrusion that engages with an engagement hole of a magnetic disk (not shown).

[0013] lower end of the bearing 2 with a cylindrical bearing surface is sealed by a shaft sealing 9 of nylon, and supporting the circular end 3 ₁ of the spindle shaft 3 which is inserted into the bearing 2.

The spindle 3 for holding the rotor 5
Are merely inserted and supported by the bearing 2, and are held against the upward force of the spindle shaft 3 by the gravity of the rotor 5 and the attractive force acting on the magnet 4. FIG. 2 shows details of the bearing 2. The inner peripheral surface of a circular bearing portion 21 of the bearing 2 is provided with four circumferentially spaced whirl preventing grooves 21 ₁ at approximately upper half positions of the bearing. ~ 21
₄ are formed.

[0015] Once the inserting the spindle shaft 3 while blocked with the shaft stopper 10, the space A between the shaft end portion 3 ₁ and the shaft stopper 10 which forms a circular curved surface of the spindle shaft 3 is formed. Groove prevention grooves 21 _{1 to} 21
₄ does not reach the lower end, so the space A and each groove 21
₁ to 21 ₄ and are interrupted by the spindle shaft 3, the space A, is blocked with an external bearing 2, by the same reason as described in conjunction with FIG. 9, the enclosed space.

The operation of this embodiment will be described.

[0017] When the spindle shaft 3 of the motor that is inserted into the bearing 2 is rotated by the presence of the grooves 21 ₁ to 21 ₄ for preventing whirl formed on the inner surface of the bearing portion 21, the generation of axial deflection due to whirl phenomenon Is suppressed.

Next, the bearing 2 is attached to the spindle shaft 3 of the motor 1.
A case in which a force is applied in the direction (arrow X) from the exit will be described with reference to FIG.

FIG. 3A shows that the spindle shaft 3 is
1 shows a state where the shaft end 31 of the spindle shaft 3 is inserted into the shaft stopper _{1 and} is in contact with the shaft stopper 10.

Now, assuming that the volume of the sealed space A formed between the spindle shaft 3 and the bearing 21 is V, and that the pressure in the space and the external pressure at that time are P, PV = constant (however,
(The temperature is constant).

At this time, as shown in FIG. 3B, a force for pulling the spindle shaft 3 upward in the axial direction indicated by the arrow X is applied, and the spindle shaft 3 is displaced upward by Δx.
Assuming that the volume increases from V to V + Δv and the pressure at that time is P ′, P ′ (V + Δv) = PV (1) holds, and therefore P ′ = PV / (V + Δv) (2)

At this time, the pressure difference between the external pressure P and the space pressure P ′ is expressed by the following equation: PP ′ = P−PV / (V + Δv) = PΔv / (V + Δv) (3) It works in the direction to negate. Thus, when a force is applied to the spindle shaft 3 of the motor 1 from the bearing 2 to remove the force, a force acting in a direction to cancel the force acts on the spindle shaft 3, thereby preventing the spindle shaft 3 from coming off.

When a force in the direction opposite to the arrow X acts on the spindle shaft 3, the gas in the closed space is compressed, and functions as a damper.

FIG. 4 shows a bearing 30 of another motor according to the embodiment of the present invention. The bearing 30 is formed with four whirl prevention groove 31 _{1-31 4} spaced on the inner peripheral surface of the substantially lower half portion in the circumferential direction of the bearing portion 31.

In this embodiment, as in the embodiment shown in FIG. 2, communication between the space A below the bearing and the outside 31 of the bearing is cut off by the spindle shaft 3, and the lower space A becomes a closed space.

[0026] Therefore, as in the embodiment, the whirl prevention groove 31 _{1-31 4} suppresses the deflection axis by whirl phenomenon, enclosed space A which is formed in the lower bearing
Can prevent the spindle shaft from coming off.

FIG. 5 shows a motor bearing 40 according to a third embodiment of the present invention.

In the bearing 40 according to the present embodiment, four upper grooves 42 are provided on the inner peripheral surface of the bearing portion 41 as grooves for preventing whirl.
_{1-42 4} as being four ones to form a lower groove 43 _{1-43 2.}

[0029] to form out of phase with one another circumferentially and upper grooves 42 ₁ to 42 ₄ for preventing whirl and lower grooves 43 ₁ to 43 _2. Therefore, when the spindle shaft 3 of the motor is inserted into the bearing 40, the space A below the bearing is isolated from the outside of the bearing by the spindle shaft 3, and the lower space A becomes a closed space.

[0030] In this embodiment, as in the previous embodiment, with axial runout due to whirl phenomenon can be suppressed by the upper groove 42 _{1-42 4} and the lower groove 43 _{1-43 4} for preventing whirl, bearing lower The formation of the closed space A prevents the spindle shaft from coming off. According to this embodiment, since the groove for preventing whirl is formed over the entire length of the bearing, the effect of suppressing shaft runout due to the whirl phenomenon can be more effectively achieved.

In each of the embodiments described above, the groove for preventing whirl is formed on the inner peripheral surface of the bearing portion of the bearing. However, the groove for preventing whirl is not limited to this, and may be formed on the outer peripheral surface of the spindle shaft. It can also be formed.

FIG. 6 shows an example in which a whirling prevention groove is formed on the outer peripheral surface of the spindle shaft.

The spindle shaft 50 is equivalent to the spindle shaft 3 of the motor in FIG. 1. On the outer peripheral surface of the spindle shaft 50, there are four whirling prevention grooves in the upper half of the spindle shaft 30. grooves 51 ₁ to 51 _4, also in the bottom half four lower grooves 52 ₁ to 52 ₄ are formed. The upper grooves 51 _{1 to} 51 ₄ and the lower grooves 52
_{1-52 4} and is disposed out of phase in the circumferential direction.

The spindle shaft 50 is used by inserting the bearing into a bearing having a smooth inner peripheral surface.

In this embodiment, the whirl grooves formed in the bearing surface in the embodiment shown in FIG. 5 are provided on the spindle shaft side, and the same operation and effect as those in the embodiment shown in FIG. 5 can be obtained.

Similarly, it goes without saying that the present invention can be implemented by forming the whirl grooves formed on the bearing side of the embodiment shown in FIGS. 2 and 4 on the spindle shaft side.

[0037]

According to the present invention, a groove for preventing whirl is formed on the bearing surface of a plain bearing in which whirl is liable to occur to prevent shaft wobble due to the whirl and to provide a groove for preventing whirl. Also, the space between the bearing and the end of the spindle shaft does not communicate with the outside of the bearing, and the space at the end can be kept in a closed space. Accordingly, when a force acts on the spindle shaft of the motor in a direction in which the shaft comes off, a force in a direction to suppress the force can be generated, and the shaft of the motor can be prevented from coming off. Further, since the sealed space also functions as a kind of damper, even if a shock or vibration is applied to the motor in the axial direction of the motor, the influence can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a motor to which the present invention is applied.

FIG. 2 is a view showing one embodiment of a bearing structure according to the present invention.

FIG. 3 is an operation explanatory view of the present invention.

FIG. 4 is a view showing one embodiment of a bearing structure according to the present invention.

FIG. 5 is a view showing one embodiment of a bearing structure according to the present invention.

FIG. 6 is a view showing one embodiment of a bearing structure according to the present invention.

FIG. 7 is a view showing a conventional smooth cylindrical slide bearing.

FIG. 8 is a diagram showing a conventional grooved plain bearing.

FIG. 9 is a view showing an end structure of a conventional smooth cylindrical plain bearing.

FIG. 10 is a view showing an end structure of a conventional grooved plain bearing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Motor 2, 30, 40 Bearing 3, 50 Spindle shaft 4 Magnet 5 Rotor 6 Core 7 Coil 8 Stator part 10 Shaft stop 21 _{1 to} 21 ₄ Whirl preventing groove 31 _{1 to} 31 ₄ Whirl preventing groove 42 _{1 to} 42 ₄ whirl prevention groove 43 _{1-43 4} whirl prevention groove 51 _{1-51 4} whirl prevention groove 52 _{1-52 4} whirl prevention groove

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16C 33/08 F16C 17/02

Claims (1)

(57) [Claims] A magnet mounted on the magnetic disk;
A spindle shaft for supporting the rotor projection is provided to engage with the engagement holes of the disc, journalled said spindle shaft, co
A bearing structure for a magnetic disk motor, comprising a stator portion provided with a sliding bearing fixed to a substrate on which the coil and the core are fixed , wherein the sliding bearing supports the rotor. The end opposite to the side to be sealed is sealed, and a space formed by the end of the spindle shaft and the slide bearing is formed on the inner peripheral surface of the bearing portion of the slide bearing or the outer peripheral surface of the spindle bearing. A bearing structure for a magnetic disk motor in which a groove is formed so as not to communicate with the outside of the slide bearing.