JPH0715338Y2 - Brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a brushless motor, and more particularly to improvement of a brushless motor suitable for a capstan motor such as a tape recorder.

(B) Conventional Technology Conventionally, as a brushless motor of this type, as shown in FIGS. 4 and 5, a cylindrical stator casing 1 includes an oilless metal 3 and a ball bearing 5 in which oil is impregnated. Mounting, a stator yoke 7 is mounted on the outer periphery of the stator casing 1, a circuit board 11 having a plurality of drive coils 9 is superposed on the stator yoke 7, and a rotor yoke 15 having a main magnet 13 facing the drive coils 9 is provided.
To the rotor shaft 19 via the mounting member 17
A configuration is known in which the rotor shaft 19 is formed, the rotor shaft 19 is projected from the ball bearing 5 side through the oilless metal 3, and the rotor 21 is rotatably supported by the ball bearing 5 and the oilless metal 3. .

A pulley 23 for rotating the hub shaft of the tape recorder is formed on the mounting member 17, and a cylindrical contact portion 25 is hung on the mounting member 17 to contact the inner ring of the ball bearing 5. ing.

Such a brushless motor has a pinch roller (not shown) on the rotor shaft 19 portion protruding from the oilless metal 3.
Can be brought into contact with each other, and the magnetic tape can be sandwiched between them to run at a constant speed.

However, in this brushless motor, if the rotor shaft 19 is held so as not to move in the axial direction by the attractive force between the main magnet 13 attached to the rotor yoke 15 and the stator yoke 7, a strong shock will occur. As the rotor shaft 19 may move in the axial direction due to factors such as the above, the rotor yoke 15 and the rotor shaft 19 may be distorted, or in extreme cases,
21 may be omitted.

Therefore, conventionally, the rotor 21 is covered with a stopper plate 26 so as not to come into contact with the rotor 21 and is attached to the circuit board 11.

(C) Problems to be solved by the invention However, in the brushless motor using the stopper plate 26 as described above, the presence of the stopper plate 26 is an obstacle to downsizing, particularly thinning, and it has a bad appearance. There is a bad drawback. Moreover, the work of screwing the stopper plate 26 to the circuit board 11 so as not to contact the rotor 21 is complicated.

The present invention has been made in order to solve such a conventional drawback, and an object of the present invention is to obtain a brushless motor which is small in size and has a good external appearance without the rotor coming off.

(D) Means for Solving the Problems In order to solve such problems, the present invention, as shown in FIGS. 1 to 3, includes a bearing portion including a ball bearing 1 on the stator side and a stator yoke. 7, a plurality of drive coils 9 are arranged on the upper side of the stator yoke 7, and a rotor yoke 15 having a main magnet 13 facing the drive coils 9 is attached to a rotor shaft 19 via an attachment member 17 to form a rotor. 21 is formed, the rotor shaft 19 is made to project the oilless metal 3 from the side of the ball bearing 5 and is axially supported by these, and the abutment portion 25 that abuts the inner ring of the ball bearing 5 from its mounting member 17. To project,
A flange 33 is formed on the abutting portion 25, and a slip-off preventing member 41 is formed by projecting an engaging portion 39 that engages with the flange 33 on the tip end portion in a radial direction.
The engaging portion 39 is erected from the stator side so that the engaging portion 39 is positioned with play in the space between the spaces 33.

(E) Action The brushless motor of the present invention equipped with such means is
When the rotor 21 rotates, the engaging portion 39 of the slip-off preventing member 41 does not abut the mounting member 17 such as the flange 33, so that the rotor 21 rotates smoothly, and if the impact is applied and the rotor 21 tries to slip out, the slip-off suppressing The engaging portion 39 of the member 41 engages with the flange 33 to prevent the flange 33 from coming off.

(F) Example An example of the present invention will be described below. The same parts as those in the conventional example are designated by the same reference numerals.

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

A hollow portion 27 is formed in the tubular stator casing 1, and an oilless metal 3 and a ball bearing 5 are attached to both ends of the hollow portion 27.

The stator yoke 7 is superposed on the support piece 29 provided on the outer periphery of the stator casing 1, and the circuit board 11 is superposed on the stator yoke 7 via an insulating layer. Drive coil 9 is arranged so as to surround the stator casing 1.

On the other hand, the rotor 21 has a main magnet 13 facing the drive coil 9 inside a cup-shaped flat rotor yoke 15, and the rotor yoke 15 is attached to a rotor shaft 19 via an attachment member 17. .

That is, as shown in FIG. 2, the rotor yoke 15 has a through hole 31 in the center thereof and a pulley formed on the mounting member 17.
23 is fixed to one end surface of 23 by caulking the edge of the through hole 31, and the mounting member 17 has a cylindrical contact portion 25 extending so as to contact the inner ring of the ball bearing 5, A flange 33 is integrally formed from the outer circumference of the contact portion 25.

The flange 33 has a larger diameter than the ball bearing 5.

The rotor shaft 19 protrudes from the ball bearing 5 side through the oilless metal 3 and is rotatably supported by the ball bearing 5 and the oilless metal 3.

On the circuit board 11 on the outer circumference of the stator casing 1,
As shown in FIG. 3, a ring-shaped base portion 35, three restraining pieces 37 standing upright from the inner end thereof, and an engaging portion 39 projecting inward from the top of the restraining piece 37. The slip-off preventing member 41 consisting of is overlapped with the screw hole 43 formed in the base portion 35.
Is attached by screwing the screw 45 to the support piece 29 of the stator casing 1.

The restraining piece 37 is formed so as to be spaced from the outer periphery of the flange 33, and the engaging portion 39 at the tip of the restraining piece 37.
Are positioned so that the space between the mounting member 17 and the flange 33 has a play so that they do not come into contact with each other.

Further, as shown in FIG. 2, the attachment member 17 has a pulley 23 at a position corresponding to the engaging portion 39 of the slip-off preventing member 41.
An insertion hole 47 is formed so as to penetrate the rotor 21, and the rotor 21 can be pulled out by inserting a jig 49 and expanding the holding piece 37 of the coming-off prevention member 41.

Although only one insertion hole 47 is shown for the sake of convenience, it is formed according to the retaining piece 37 of the retaining member 41.

When assembling the brushless motor of the present invention as described above, the rotor shaft 19 of the rotor 21 is inserted from the ball bearing 5 side toward the oilless metal 3, and the flange 33 of the mounting member 17 prevents the detachment member 41. When the rotor 21 is removed, the jig 49 is inserted into the insertion hole 47 and removed.

It is to be noted that the above-described brushless motor slip-off prevention member 41 is independently formed, and is stacked on the circuit board 11 and attached to the stator casing 1 together with the circuit board 11 and the stator yoke 7 by the screw 45. 41
In this case, the stator casing 1 can be integrally formed by outsert molding.

(G) Effects of the Invention As described above, the brushless motor of the present invention includes the mounting member 17 for mounting the rotor yoke 15 on the rotor shaft 19,
A flange is provided on the contact portion 25 extending to the inner ring of the ball bearing 5.
A retaining member 41 having an engaging portion 39 for forming the 33 and engaging with the flange 33 is provided in the space between the mounting member 17 and the flange 33 so that the engaging portion 39 has a play. Since it is attached to the stator side, the conventional stopper plate 26
Even if is omitted, the rotor 21 does not come off, the size is reduced, especially the thickness is reduced, and the assembly is easy and the appearance is good.

[Brief description of drawings]

1 is a cross-sectional view showing an embodiment of the brushless motor of the present invention, FIG. 2 is an enlarged cross-sectional view for explaining the essential parts of FIG. 1, and FIG. 3 is a perspective view of the slip-out prevention member of FIG. FIG. 4 and FIG. 5 are a half sectional view and a plan view showing a conventional brushless motor. 1 …… stator casing, 3 …… oilless metal,
5 ... Ball bearing, 7 ... Stator yoke, 9 ...
… Drive coil, 11 …… Circuit board, 13 …… Main magnet,
15 …… Rotor yoke, 17 …… Mounting member, 19 …… Rotor shaft, 21 …… Rotor, 25 …… Abutting part, 33 …… Flange, 35
...... Base part, 37 ...... Retainer, 39 ...... Engagement part, 41 ...... Detachment prevention member, 45 ...... Screw, 47 ...... Insertion hole.

Claims (1)

[Scope of utility model registration request] 1. A stator having a bearing portion including a ball bearing, to which a stator yoke is attached, a drive coil disposed above the stator yoke, and a rotor shaft rotatably supported by the bearing portion. A mounting member for mounting a rotor yoke having a main magnet facing the drive coil to the rotor shaft, the mounting member being mounted on the end of the rotor shaft projecting from the ball bearing side, and abutting against the inner ring of the ball bearing. A brushless motor comprising: a mounting member having a protruding contact portion; and a flange formed at the contact portion of the mounting member, the engaging portion being erected from the stator side and protruding in the radial direction at the tip end portion. A retaining member having a retaining side formed with an arrangement is arranged so that the engaging portion is positioned with play in the gap between the mounting member and the flange. Brushless motor, characterized in that it is.