JPH10322957A - Shaft rotation type of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary shaft for a motor which can prevent the dissipation of lubricant used for a sintered oil-containing bearing, without performing the work required such as a labor to form a collar or a groove at the periphery of a rotary shaft. SOLUTION: In a motor 1 in this mode, an oil sump is constituted, with an outer end face 51 of a first sintered oil-containing bearing 5 indented from the edge of a bearing holder 4. Moreover, the outer end face 51 of the first sintered oil-containing bearing 5 is indented, and besides the interval between the outer end face 51 of the first sintered oil-containing bearing 5 is substantially widened by the formation of a circular groove 96 to a rotor case 8, whereby lubricant is prevented from adhering to the rotor case 8. A scattering path is made complex and narrow, so that a lubricant 38 does not scatter around, even if the lubricant 38 adheres into the circular groove 96 of the rotor case 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary shaft motor having a rotary shaft supported by a sintered oil-impregnated bearing. More specifically, the present invention relates to a structural technique for preventing the lubricating oil used for a sintered oil-impregnated bearing from disappearing.

[0002]

2. Description of the Related Art A motor for rotating a polygon mirror in an optical scanning device of a laser printer includes a stator having a cylindrical bearing holder in which a pair of sintered oil-impregnated bearings are coaxially fitted. A so-called rotary shaft motor having a rotary shaft rotatably supported on a stator by an oil-impregnated bearing and a rotor having a rotor case fixed to the rotary shaft is used. Here, of both ends of the bearing holder, the end facing the flat inner surface of the rotor case is an open end, and when assembling or inspecting the motor, lubricates the sintered oil-impregnated bearing therefrom. It is possible to supply oil.

[0003]

However, as the motor is made thinner, the distance between the end of the bearing holder and the inner surface of the rotor case is becoming narrower. An event has occurred in which the used lubricating oil disappears in a short period of time and oil runs out. That is, if the distance between the bearing holder and the inner surface of the rotor case opposed to the bearing holder is small, the lubricating oil supplied to the end surface of the sintered oil-impregnated bearing or the lubricating oil oozing out of the sintered oil-impregnated bearing may be reduced. The lubricating oil adhering to the inner surface and adhering thereto flows out therefrom due to the centrifugal force generated by the rotation of the rotor.

In order to avoid this problem, Japanese Patent Laid-Open Publication No.
No. 03047 discloses that a flange or a groove is formed on an outer peripheral surface of a rotating shaft exposed between a sintered oil-impregnated bearing and a rotor case so that lubricating oil used for the sintered oil-impregnated bearing reaches the inner surface of the rotor case. A disclosed structure is disclosed. However, in order to form such a structure, it is necessary to add a troublesome operation of forming a flange or a groove on the outer peripheral surface of the rotary shaft, and thus there is a problem that productivity is reduced.

Accordingly, an object of the present invention is to prevent the lubricating oil used in the sintered oil-impregnated bearing from disappearing without performing a troublesome operation of forming a flange or a groove on the outer peripheral surface of the rotating shaft. An object of the present invention is to provide a shaft rotation type motor.

[0006]

According to the present invention, there is provided a stator having a bearing housing in which a pair of sintered oil-impregnated bearings are coaxially arranged in a cylindrical portion; A rotary shaft rotatably supported by the stator with respect to the stator and a rotor having a rotor case fixed to the rotary shaft, wherein the rotor case comprises a pair of sintered oil-impregnated bearings. The sintered oil-impregnated bearing arranged on the side has an outer end surface located at a position retracted from an edge of the bearing housing, and a surface of the rotor case facing the sintered oil-impregnated bearing includes a periphery of the rotating shaft. An annular groove that is recessed by a groove is formed.

In the present invention, between the sintered oil-impregnated bearing and the rotor case, the outer end surface of the sintered oil-impregnated bearing is located at a position retracted from the edge of the bearing housing, while facing the sintered oil-impregnated bearing of the rotor case. Since the annular groove is formed around the rotating shaft of the surface, that is, the portion facing the sintered oil-impregnated bearing, the distance between the outer end surface of the sintered oil-impregnated bearing and the opposing surface of the rotor case is substantially extended. Have been. Therefore, the lubricating oil used for the sintered oil-impregnated bearing does not reach the opposed surface of the rotor case without forming a flange or a groove on the outer peripheral surface of the rotating shaft. Also, the outer end surface of the sintered oil-impregnated bearing is located at a position retracted from the edge of the bearing housing, and the edge of the bearing housing protrudes from the outer end surface of the sintered oil-impregnated bearing. The upper surface is in a state where an oil reservoir is formed. Therefore, even if the lubricating oil oozes out of the sintered oil-impregnated bearing, or even if the lubricating oil is supplied to the sintered oil-impregnated bearing, the lubricating oil is only held in the oil sump, so that Does not adhere to the opposing surface. Therefore, since the lubricating oil is not scattered by the centrifugal force when the rotor rotates, the lubricating oil can be prevented from disappearing from the sintered oil-impregnated bearing, and no oil break occurs. Therefore, the life and rotation characteristics of the motor can be improved. Furthermore, since there is no scattering of the lubricating oil, the surroundings are not stained with the lubricating oil.

In the present invention, the opposed surface of the rotor case is bent so as to face the outer peripheral surface of the bearing housing, and the outer peripheral surface of the bearing housing is formed with a narrow gap of, for example, about 0.1 mm to 1.0 mm. It is preferable that a surrounding cylindrical inner peripheral side surface is formed. With this configuration, even if the lubricating oil adheres to the inside of the annular groove of the rotor case, the wall surface of the annular groove or the inner peripheral side surface of the rotor case acts as a barrier to prevent scattering to the outside. Since the lubricating oil cannot be scattered to the outside unless it passes through a complicated and narrow path from the sintered oil-impregnated bearing to the rotor case, the lubricating oil can be surely prevented from being scattered to the outside also by the labyrinth effect.

The rotating shaft type motor constructed as above does not run out of oil or scatter of lubricating oil, so that high rotational accuracy is required and dirt on lubricating oil is a fatal problem. Suitable for rotary drive of

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

(Overall Configuration) FIG. 1 is a cross-sectional view showing the structure of a rotary shaft type motor to which the present invention is applied.

The shaft rotation type motor 1 of the present invention shown in FIG.
The stator 2 is for rotating a polygon mirror 32 used in an optical scanning device of a laser beam printer. The stator 2 includes a motor substrate 21 and a cylindrical bearing holder 4 (bearing housing) fixed to the motor substrate 21.
And a stator core 26 in which the winding 24 is wound around a plurality of salient poles 25 extending radially. Bearing holder 4
, A first sintered oil-impregnated bearing 5 and a second sintered oil-impregnated bearing 6 are coaxially arranged. These sintered oil-impregnated bearings 5 are impregnated with a lubricating oil 38 and replenished with a lubricating oil 38 containing grease so as to be less likely to be scattered, thereby improving the lubricating properties. Also, the rotor 3
Has a rotating shaft 7 rotatably supported by the pair of sintered oil-impregnated bearings 5 and 6 and a rotor case 8. The rotor case 8 includes a boss 9 fixed to the rotating shaft 7, Rotor case body 1 fixed to rotating shaft 7 via boss 9
0.

The boss 9 has a thick disk shape, and the rotary shaft 7 is fitted and fixed in a fitting hole 91 formed in the center.
The lower half 92 of the boss 9 is formed to have a larger diameter than the upper half 93, and the polygon mirror 32 is mounted using the step. A mirror holding cap 33 having a diameter larger than that of the upper half portion 93 is attached to the upper surface of the boss 9, and the mirror holding cap 33 is fixed on the boss 9 by fixing a screw 34 in a screw hole 94 of the boss 9. . A spring 35 is arranged between the outer periphery of the mirror pressing cap 33 and the polygon mirror 32, and the polygon mirror 32 is pressed and fixed to the boss 9 by the spring 35.

The rotor case body 10 has an upper surface 11 extending outwardly along the lower surface of the boss 9 and an outer peripheral portion 12 which is bent at a right angle downward from the outer peripheral edge of the upper surface 11. A rotor magnet 31 is adhered and fixed to the inner peripheral surface of the rotor magnet so as to face the distal end surface of the salient pole 25. Therefore, the rotor magnet 31 and the stator core 2
Due to the magnetic force generated between the rotor 3 and the polygon mirror 32, the rotor 3 is integrated with the polygon mirror 32 and the axis of the rotating shaft 7 (motor axis 7
1) It is rotatable around.

(Structure of Bearing Part) The bearing holder 4
It comprises a cylindrical portion 41 corresponding to the body and a flange 42 connected to the lower end of the cylindrical portion 41. The cylindrical portion 41 of the bearing holder 4 has a holder mounting hole 22 of the motor substrate 21 and a center hole 27 of the stator core 26.
The motor board 2 is inserted in this state.
1 and the stator core 26 are fixed with screws 29. Note that a screw 29 is provided between the upper surface of the motor board 21 and the stator core 26 so that the coil winding 24 wound around the stator core 26 does not contact the motor board 21.
An insulating sleeve 30 is disposed over the insulating sleeve 30.

Inside the cylindrical portion 41 of the bearing holder 4,
A projection 46 protruding toward the center is formed at a central portion in the direction of the motor axis 71, and the first bearing 5 and the second bearing 6 are provided at the upper position and the lower position by using the projection 46. Are coaxially positioned and fixed.
Here, the height dimension of the cylindrical portion 41 of the bearing holder 4, the formation position of the protrusion 46, and the length dimension of the first sintered oil-impregnated bearing 5 are respectively set inside the cylindrical portion 41 of the bearing holder 4. When the sintered oil-impregnated bearing 5 is fixed, the outer end surface 51 of the first sintered oil-impregnated bearing 5 is fixed to the upper end edge 4 of the bearing holder 4.
9 is set so as to be retracted. Note that the first sintered oil-impregnated bearing 5 and the second sintered oil-impregnated bearing 6
The lower end surface 62 of the second sintered oil-impregnated bearing 6 is located at a position retracted from the lower end edge of the bearing holder 4.

The lower end surface of the bearing holder 4 is
6, a thrust bearing 37 is formed on the upper surface of the circular plate 36.

(Lubricant Oil Loss / Scattering Prevention Structure) In the shaft rotation type motor 1 thus configured, in the present embodiment,
From the viewpoint of preventing the loss of the lubricating oil used for the sintered oil-impregnated bearing without performing the troublesome work of forming a flange or a groove on the outer peripheral surface of the rotating shaft 7, the periphery of the bearing portion is as follows. It is composed.

First, as described above, of the first and second sintered oil-impregnated bearings 5 and 6, the first sintered oil-impregnated bearing 5 disposed on the rotor case 8 side has an outer end surface 51 having a bearing holder. 4 is retracted from the edge 49. Therefore, the distance between the outer end surface 51 of the first sintered oil-impregnated bearing 5 and the lower end surface 95 of the boss 9 (the opposing surface of the rotor case 8 opposed to the first sintered oil-impregnated bearing 5) is equal to the first sintered oil-impregnated bearing. Oil-impregnated bearing 5
The outer end surface 51 of the bearing holder 4 is wider than that of the end edge 49 of the bearing holder 4. Conversely, since the edge 49 of the bearing holder 4 protrudes from the outer end surface 51 of the first sintered oil-impregnated bearing 5, the upper surface of the outer end surface 51 of the first sintered oil-impregnated bearing 5 has the first surface. Of the lubricating oil 38 supplied to the sintered oil-impregnated bearing 5 described above.

The lower end surface 95 of the boss 9 (the surface facing the rotor case 8) is provided around the rotary shaft 7 (a portion facing the outer end surface 51 of the first oil-impregnated bearing 5). An annular groove 96 is formed by a circular recess 97 that is vertically recessed at the center of the lower end surface 95 and the outer peripheral surface of the rotating shaft 7. Therefore, the distance between the outer end surface 51 of the first sintered oil-impregnated bearing 5 and the lower end surface 95 of the boss 9 (the surface facing the rotor case 8) is increased by the depth of the annular groove 96. That is, the annular groove 96 serves as a relief portion for preventing the lubricating oil 38 used for the first sintered oil-impregnated bearing 5 from adhering to the rotor case 8 as described later. For example, when the distance L1 between the outer end surface 51 of the first sintered oil-impregnated bearing 5 and the lower end surface 95 of the boss 9 is about 1.0 mm, the depth L2 is 0.4 m.
m, the distance between the outer end surface 51 of the first sintered oil-impregnated bearing 5 and the boss 9 is substantially 1.4 mm, which is the sum of the above dimensions L1 and L2. In addition, the annular groove 96 sufficiently functions as a relief portion for preventing the lubricating oil 38 from adhering to the rotor case 8 as described later. Further, as long as the recess 97 is formed in the lower end face 95 of the boss 9 to form the annular groove 96, press working or simple working is sufficient.

As described above, in this embodiment, since the distance between the outer end surface 51 of the first sintered oil-impregnated bearing 5 and the facing surface of the rotor case 8 is substantially expanded, the outer peripheral surface of the rotating shaft 7 Even without forming a flange or a groove, the lubricating oil 38 used for the first sintered oil-impregnated bearing 5 does not reach the facing surface of the rotor case 8.
Even if the lubricating oil 38 oozes out of the first sintered oil-impregnated bearing 5, the lubricating oil 3
Even if the lubricating oil 8 is replenished, the lubricating oil 38 is merely held in the oil sump surrounded by the edge 49 of the bearing holder 4 above the outer end surface 51 of the first sintered oil-impregnated bearing 5. Does not adhere to the opposite surface of Therefore, the lubricating oil 38 does not scatter due to the centrifugal force when the rotor 3 rotates, so that the loss of the lubricating oil 38 from the first sintered oil-impregnated bearing 5 can be prevented, and Does not occur. Therefore,
The life and rotation characteristics of the motor 1 can be improved. Furthermore, since the distance between the outer end surface 51 of the first sintered oil-impregnated bearing 5 and the opposing surface of the rotor case 8 is substantially extended, the first sintered oil-impregnated bearing 5 is attached to the motor 1 during assembly and inspection. Even when the lubricating oil 8 is supplied, the lubricating oil 8 supplied thereto does not adhere to the rotor case 8, so that the assembling work of the motor 1 is easy. Moreover, the rotor case 8
Since the lubricating oil 38 does not adhere to the rotor 3, the lubricating oil 38 does not scatter and does not pollute the surroundings even when the rotor 3 rotates.

Further, in the present embodiment, the lower end face 95 of the boss 9 is vertically bent downward so as to face the outer peripheral side face 44 of the bearing holder 4.
A cylindrical inner peripheral side surface 98 surrounding the outer peripheral side surface 44 of the bearing holder 4 is formed. Moreover, the inner peripheral side surface 98 of the boss 9
The gap L3 between the outer peripheral side surface 44 of the bearing holder 4 and
It is as narrow as 0.1 mm to 1.0 mm. Therefore, even if the lubricating oil 38 adheres to the annular groove 96 of the rotor case 8, the side wall of the annular groove 38 and the inner peripheral side surface 98 of the boss 9 (the inner peripheral side surface of the rotor case 8) serve as a barrier and lubricate. The lubricating oil 38 cannot be scattered outside unless it passes through a complicated and narrow path from the first sintered oil-impregnated bearing 5 to the rotor case 8 such that scattering of the oil 38 to the outside is prevented. Accordingly, it is possible to prevent the lubricating oil 38 from scattering to the outside.

Therefore, the motor 1 according to the present embodiment requires high rotational accuracy, as is the case with a motor for rotating the polygon mirror 32 in an optical scanning device of a laser printer, and causes dirt from the lubricating oil 38 to be fatal. It is particularly suitable for applications that may cause problems.

(Other Embodiments) As shown in FIG. 1, the structure of the annular groove 96 formed in the rotor case 8 has a constant depth and the bottom surface 99 has the first sintered oil-impregnated bearing 5.
Not only the annular groove 96 parallel to the outer end surface 51 of the rotary shaft 7 but also a bottom surface 99 having a taper such that the side of the rotating shaft 7 (the inner peripheral side) is deep and the outer peripheral side is shallower from the side as shown in FIG. The annular groove 96 may be provided. With this configuration, the annular groove 96 is deep on the side of the rotating shaft 7 (the inner peripheral side) where the lubricating oil used for the first sintered oil-impregnated bearing 5 is most easily reached, so that the lubricating oil 38 adheres to the rotor case 8. Can be effectively prevented.

Although the shaft rotation type motor 1 for rotating the polygon mirror 32 has been described, the present invention is not limited to a shaft rotation type motor using a sintered oil-impregnated bearing, as long as the polygon mirror 32 is rotated. Absent.

Further, the example in which the sintered oil-impregnated bearing is disposed in the bearing holder has been described, but the sintered oil-impregnated bearing is not limited to the bearing holder, and is constituted by using a part of various devices. It may be arranged in a housing.

[0027]

As described above, in the rotary shaft type motor according to the present invention, since the distance between the sintered oil-impregnated bearing and the rotor case is substantially extended, the motor is used for the sintered oil-impregnated bearing. The lubricating oil does not reach the opposing surface of the rotor case without forming a flange or a groove on the outer peripheral surface of the rotating shaft. Also, the outer end surface of the sintered oil-impregnated bearing is located at a position retracted from the edge of the bearing housing, and the edge of the bearing housing protrudes from the outer end surface of the sintered oil-impregnated bearing. The upper surface is in a state where an oil reservoir is formed. Therefore, even if the lubricating oil oozes out of the sintered oil-impregnated bearing, or even if the lubricating oil is supplied to the sintered oil-impregnated bearing, the lubricating oil is only held in the oil sump, so that Does not adhere to the opposing surface. Therefore, since the lubricating oil is not scattered by the centrifugal force when the rotor rotates, the lubricating oil can be prevented from disappearing from the sintered oil-impregnated bearing, and no oil break occurs. Therefore, the life and rotation characteristics of the motor can be improved. Furthermore, since there is no scattering of the lubricating oil, the surroundings are not stained with the lubricating oil.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a rotary shaft type motor to which the present invention is applied.

FIG. 2 is a cross-sectional view showing a modified example of an annular groove formed in a lower end surface of a boss in the motor shown in FIG.

[Explanation of symbols]

 1 shaft rotary type motor 2 stator 3 rotor 4 bearing holder (bearing housing) 5 first sintered oil-impregnated bearing 6 second sintered oil-impregnated bearing 7 rotary shaft 8 rotor case 9 boss 10 rotor case body 38 lubricating oil 44 bearing Outer peripheral surface of holder 49 Upper edge of bearing holder 51 Upper surface of first sintered oil-impregnated bearing 96 Annular groove formed in boss (annular groove of rotor case) 98 Inner peripheral surface of boss (inner peripheral surface of rotor case)

Claims (4)

[Claims] A stator having a bearing housing in which a pair of sintered oil-impregnated bearings are coaxially arranged within a cylindrical portion;
A shaft rotating type motor having a rotating shaft rotatably supported by the sintered oil-impregnated bearing with respect to the stator and a rotor having a rotor case fixed to the rotating shaft; Among them, the sintered oil-impregnated bearing arranged on the rotor case side has an outer end surface at a position retracted from an edge of the bearing housing, and a surface of the rotor case facing the sintered oil-impregnated bearing, A shaft rotation type motor, wherein an annular groove recessed around the rotation shaft is formed. 2. The bearing surface according to claim 1, wherein the opposed surface of the rotor case is bent so as to face the outer peripheral surface of the bearing housing to form a cylindrical inner peripheral surface surrounding the outer peripheral surface of the bearing housing. A rotary shaft type motor. 3. The shaft rotary type according to claim 2, wherein a clearance dimension between an inner peripheral side surface of the rotor case and an outer peripheral side surface of the bearing housing is in a range of 0.1 mm to 1.0 mm. motor. 4. The method according to claim 1, wherein
A shaft rotation type motor, wherein a polygon mirror is mounted on the rotor case.