JPH0541387U - Brushless motor - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to obtain a brushless motor capable of simplifying the structure of the pressurizing means and facilitating the manufacture of the rotating shaft of the rotor. Structure: A pressurizing means 32 for applying a thrust force in the direction of the hub 8 to a ball bearing 8 remote from the hub 11 of a rotor 9 and a mounting hole 35 having a size equal to the outer diameter of a rotary shaft 31 of the rotor 9. A spring receiving plate 33, which has a passive portion 36 which is provided in the center portion and which receives a rotational driving force when the rotating body attachment surface 15 of the hub 8 is finished by cutting, and the spring receiving plate 33. It is formed by a ring-shaped thrust spring 34 sandwiched between the plate 33 and the ball bearing 8 in a compressed state, and the spring receiving plate 33 is fixed to the outer circumference of the rotary shaft 31 by press fitting or an adhesive. Characterize.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a brushless motor used, for example, for rotating a polygon mirror of a laser beam printer, and more particularly to a brushless motor with improved preload means for applying thrust force to a ball bearing that supports a rotating shaft.

[0002]

[Prior Art]

 FIG. 6 shows a conventional brushless motor for driving a polygon mirror. A plurality of projections 1a are integrally provided on the upper surface of the housing 1 of the motor, and a printed circuit board 2 provided over the projections 1a is screwed. The housing 1 integrally has an upward cylindrical portion 3 that penetrates the printed circuit board 2 and a downward cylindrical portion 4 that communicates with the cylindrical portion 3. On the printed circuit board 2, a plurality of drive coils 5 located around the upward cylindrical portion 3 are attached, and a motor drive circuit portion 6 for controlling energization of these coils 5 is attached.

In the housing 1, a pair of ball bearings 7 and 8 are provided separately from each other. That is, one ball bearing 7 is accommodated in the upward cylindrical portion 3, and the other ball bearing 8 is accommodated in the downward cylindrical portion 4. The outer race of the ball bearing 7 is positioned on the upper annular step 1b formed on the housing 1, and the outer race of the ball bearing 8 is positioned on the lower annular step 1c formed on the housing 1. ..

A pair of ball bearings 7 and 8 rotatably supports a rotor 9. The rotor 9 includes a rotating shaft 10, a hub 11 connected to one end of the rotating shaft 10, a back yoke 12, and a rotor magnet 13.

The rotary shaft 10 passes through the ball bearings 7 and 8 and is rotatably supported by them. The hub 11 is connected to, for example, the upper end of the rotary shaft 10, and the inner race of the ball bearing 7 is pushed down on the lower surface of the center of the hub 11 to sandwich the ball bearing 7 from above and below with the upper annular step 1b. It has a shaped protrusion 14. This clamping eliminates the play between the inner and outer races of the ball bearing 7 and the steel ball.

The hub 11 has a rotating body mounting surface 15 and a fitting projection 16 protruding upward from the center of the surface 15. A polygon mirror 17 as a rotated body is mounted on the hub 11 by superposing one surface thereof on a rotating body mounting surface 15 and fitting a central hole 17a of the mirror 17 into a fitting projection 16 Is being made available.

The back yoke 12 has a ring shape arranged around the upward cylindrical portion 3, and is attached to the lower surface of the peripheral portion of the hub 11. The rotor magnet 13 also has a ring shape, which is magnetized along the thickness direction and attached to the lower surface of the back yoke 12. Thereby, the rotor magnet 13 is arranged above the drive coil 5 in correspondence with the drive coil 5.

At the lower end of the rotary shaft 10, a pressurizing means 18 for applying a thrust force in the direction of the hub 11 to the ball bearing 8 farther from the hub 11 is provided. As shown in detail in FIGS. 7 and 8, this means 18 is formed of a retaining ring 19, a spring bearing plate 20, and a thrust spring 21.

The retaining ring 19 is immovable in the axial direction of the rotating shaft 10 by fitting the inner peripheral portion thereof into an annular groove 22 formed continuously in the lower end portion of the rotating shaft 10 in the axial direction thereof. Installed on. The spring receiving plate 20 is a circular plate having a central hole 20a and having a diameter larger than that of the retaining ring 19, and the central hole 20a is loosely fitted to the lower end portion of the rotary shaft 10 and is attached. The retaining ring 19 prevents movement in the axial direction. The thrust spring 21 is composed of a ring-shaped wave washer or the like, and is sandwiched between the spring bearing plate 20 and the ball bearing 8 in a compressed state. The thrust spring 21 is brought into contact with the inner race of the ball bearing 8 and applies a thrust force toward the hub 11 to the inner race so that the ball bearing 8 is provided between the thrust spring 21 and the lower annular step portion 1c. Is sandwiched from above and below. Therefore, due to this sandwiching, the play between the inner and outer races and the steel ball in the ball bearing 8 is eliminated.

A slot 23 is formed on the lower end surface of the rotary shaft 10. This groove 23 is provided in the rotor 11 when the rotating object mounting surface 15 is subjected to finishing processing in order to reduce the contact of the rotating object mounting surface 15 of the hub 11 after the brushless motor having the above structure is assembled. It is used to rotate 9 with external power.

That is, in the state where the assembled brushless motor is attached to the finishing jig, the plate-shaped tip of the rotary drive shaft (not shown) is fitted into the slot 23, and the drive is performed. The rotor 9 is rotated by the rotation of the shaft. Under this rotation, the rotating body mounting surface 15 is cut by the cutting tool.

[0012]

[Problems to be solved by the device]

 However, since the pressurizing means 18 having the above-described structure has the spring bearing plate 20 loosely fitted to and attached to the rotary shaft 10, the snap ring 19 is required, and therefore there is a problem that the number of parts is large. In addition, an annular groove 22 is provided on the rotary shaft 10 for fixing the retaining ring 19, and a slit groove 23 for receiving a rotational power from the outside is also provided at the end of the rotary shaft 10. Therefore, there is a problem that it takes time to manufacture the rotary shaft 10. An object of the present invention is to obtain a brushless motor which can simplify the structure of the pressurizing means and can easily manufacture the rotary shaft of the rotor.

[0013]

[Means for Solving the Problems]

 In order to achieve the above object, the brushless motor of the present invention comprises a pressurizing means for applying a thrust force in the direction of the hub to a ball bearing farther from the hub of the rotor and having a size equal to the outer diameter of the rotating shaft of the rotor. A spring bearing plate having a mounting hole at the center thereof and having a receiving portion around the mounting hole for receiving a rotational driving force when finishing the rotating body mounting surface of the hub by cutting. It is formed of a ring-shaped thrust spring that is sandwiched in a compressed state between a receiving plate and a ball bearing farther from the hub, and the spring receiving plate is fixed to the outer circumference of the rotary shaft by press fitting or an adhesive. It is a thing.

[0014]

[Action]

 In the above structure, the spring bearing plate is press-fitted or fixed to the rotating shaft by an adhesive and is provided without moving in the axial direction and the circumferential direction of the rotating shaft to support the thrust spring. Therefore, the retaining ring for stopping the movement of the spring receiving plate can be omitted, and accordingly, the groove processing on the rotating shaft for attaching the retaining ring to the rotating shaft can be omitted. In addition, the passive part of the spring bearing plate receives the rotational power from the outside that is applied when finishing the surface of the hub to be rotated with a bit after the motor is assembled, and transmits it to the rotating shaft to rotate the rotor. .. Therefore, it is possible to omit the machining of the slits on the rotary shaft for rotating the rotor by the external rotary power.

[0015]

【Example】

 An embodiment of the present invention will be described with reference to FIGS. In this description, the same configurations as those of the conventional example shown in FIGS. 6 to 8 are designated by the same reference numerals as those of the conventional example, and the description thereof will be omitted. Only the configurations different from the conventional example will be described below.

The present invention is different from the conventional example shown in FIGS. 6 to 8 in the configuration of the rotating shaft and the configuration of the pressurizing means. As the rotary shaft 31, a simple round bar whose outer peripheral surface does not change in diameter and whose end surface is formed into a flat surface is adopted.

The pressurizing means 32 includes a spring receiving plate 33 and a thrust spring 34. The thrust spring 34 has a ring shape and is sandwiched in a compressed state between the inner race of the ball bearing 8 remote from the hub 11 and the spring receiving plate 33. The thrust spring 34 is formed of a wave washer or the like.

As shown in FIG. 3, the spring receiving plate 33 has a mounting hole 35 having a size equal to the outer diameter of the rotary shaft 31 at the center, and a passive portion 36 around the hole 35. It is provided and formed. The passive portion 36 is formed of a pair of slit-shaped concave grooves cut from the outer periphery of the spring receiving plate 33 toward the mounting hole 35.

The spring receiving plate 33 is fixed to the outer circumference of the lower end of the rotary shaft 31 by press fitting or an adhesive so that the spring receiving plate 33 does not move either in the circumferential direction of the rotary shaft 31 or in the axial direction. The thrust spring 34 is supported on the upper surface.

In the brushless motor having the above structure, the spring bearing plate 33 of the pressurizing means 32 is fixed to the lower end portion of the rotary shaft 31 by press fitting or adhesive, so that the thrust spring is provided between the spring bearing plate 33 and the ball bearing 8. 34 can be clamped in a compressed state. Therefore, it is possible to apply a thrust force in the direction of the hub 11 to the ball bearing 8 and reduce the surface contact and whirling of the hub 11 caused by the ball bearing 8.

Since the spring bearing plate 33 fixed by press fitting or adhesive can support the thrust spring 34 without moving in the axial direction of the rotary shaft 31, a retaining ring for stopping the spring bearing plate 34 is omitted. it can. Therefore, the number of parts of the pressurizing means 32 can be reduced, and the cost can be reduced.

Moreover, since the retaining ring is not required, it is not necessary to form an annular groove for attaching the retaining ring to the rotary shaft 31 on the outer peripheral portion of the rotary shaft 31. Therefore, since a simple round bar whose diameter does not change on the outer peripheral surface can be used for the rotary shaft 31, the outer peripheral surface of the rotary shaft 31 can be easily cut.

In addition, when the rotating body mounting surface 15 of the hub 11 and the fitting protrusion 16 are finished with a cutting tool after the motor is assembled, the passive portion 36 of the spring bearing plate 33 is used to perform external rotation. The power can be transmitted to the rotating shaft 31 to rotate the rotor 9. In this case, the tip end of the rotary drive shaft (not shown) is formed into a bifurcated shape so as to fit the pair of passive parts 36, and that part is inserted into the pair of passive parts 36 to fix the rotary shaft 31 to the spring receiving plate 33. It is to rotate through. Since the rotor 9 is rotated by engaging the rotary drive shaft with the passive portion 36 of the spring receiving plate 33 in this manner, it is necessary to form a slot groove for receiving an external rotational power at the end of the rotary shaft 30. Instead, the rotary shaft 31 having a flat end surface can be used. Since the metal or synthetic resin spring bearing plate 33 is obtained by press molding or injection molding, the passive portion 36 can be formed at the same time as the molding, and the labor for specially processing the passive portion 36 is not required. Since the annular groove is not formed on the outer peripheral portion of the rotating shaft 31 and the slit groove is not formed on the end portion as described above, the rotating shaft 31 can be easily and inexpensively manufactured.

Further, the present invention is not limited to the above-mentioned embodiment, and may be implemented by using the spring receiving plate 33 having the passive portion 36 as a pair of through holes as shown in FIG. 4, for example. Alternatively, as shown in FIG. 5, the passive portion 36 may be implemented by using a spring bearing plate 33 that is a pair of protrusions extending radially outward.

[0025]

[Effect of the device]

 As described in detail above, according to the present invention, the pressurizing means for applying the thrust force in the hub direction to the ball bearing farther from the hub is centered on the mounting hole having a size equal to the outer diameter of the rotating shaft of the rotor. And a hub receiving plate that has a passive portion around the mounting hole that receives a rotational driving force when the rotating body mounting surface of the hub is finished by cutting, and the receiving plate and the hub. It is composed of a ring-shaped thrust spring that is sandwiched in a compressed state between it and a ball bearing that is farther from, and the spring bearing plate is press-fitted onto the outer circumference of the rotary shaft or fixed with an adhesive. The number of parts is reduced and the structure can be simplified, and it is not necessary to form grooves on the rotary shaft, and the rotary shaft can be manufactured easily.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a pressurizing means included in a brushless motor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of the brushless motor according to the embodiment.

FIG. 3 is a plan view showing the configuration of a spring bearing plate according to the embodiment.

FIG. 4 is a plan view showing the configuration of another spring receiving plate.

FIG. 5 is a plan view showing the configuration of still another spring receiving plate.

FIG. 6 is a sectional view showing a configuration of a brushless motor according to a conventional example.

7 is a cross-sectional view showing a configuration of a pressurizing unit included in the brushless motor shown in FIG.

8 is a bottom view showing the structure of the pressurizing means shown in FIG. 7. FIG.

[Explanation of symbols]

1 ... Housing, 7, 8 ... Ball bearing, 9 ... Rotor, 11 ...
Hub, 15 ... Rotating body mounting surface, 16 ... Fitting protrusion, 17
... Polygon mirror (rotating body), 17a ... Center hole, 31
... Rotating shaft, 32 ... Pressurizing means, 33 ... Spring receiving plate, 34 ...
Thrust spring, 35 ... Mounting hole, 36 ... Passive part.

Claims (1)

[Scope of utility model registration request] 1. A pair of rotating shafts, each of which has a hub having a surface to be rotated and a fitting projection protruding from a central portion of the surface and which is connected to one end thereof, and which is spaced from each other in a housing. Is rotatably supported by a ball bearing, and the other end of the rotary shaft is provided with a pressurizing means for applying a thrust force in the direction of the hub to the ball bearing farther from the hub. While superposing one surface on the rotating body mounting surface,
In a brushless motor in which the center hole is fitted to the fitting projection and the rotated body is mounted to the hub, the pressurizing means is centered on a mounting hole having a size equal to the outer diameter of the rotating shaft. And a spring receiving plate having a passive portion around the mounting hole for receiving a rotational driving force when finishing the mounting surface of the rotated body by cutting, and a spring receiving plate farther from the receiving plate and the hub. It is formed from a ring-shaped thrust spring that is sandwiched between it and a ball bearing in a compressed state,
A brushless motor, characterized in that the spring bearing plate is press-fitted or fixed to the outer periphery of the other end of the rotary shaft with an adhesive.