JPH099605A - Stepping motor - Google Patents

Abstract

PURPOSE: To provide a stepping motor in which the reduction of a vibration sound due to the rotation of a rotating output shaft is not spoiled by means of lubricating grease and whose starting property can be enhanced. CONSTITUTION: A rotating output shaft 12 on which a lead screw 12a has been formed protrudes from a motor body 11. A frame body 13 through which the base part 12b of the rotating output shaft 12 is passed is mounted on, and attached to, the motor body 11. A movement nut 14 which is guided by the frame body 13 so as to be moved on the lead screw 12a is screwed to the lead screw 12a. A radial bearing 15 which supports and bears the base part 12b of the rotating output shaft 12 so as to be freely rotatable is installed so as to stretch over the frame body 13 and the motor body 11. Then, a clearance groove 12c at least a part of which is faced with the radial bearing 15 is formed on the outer circumferential face of the rotating output shaft 12, and lubricating grease 24 is applied to the clearance groove 12c.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a stepping motor,
In particular, the present invention relates to a stepping motor having a rotation output shaft formed with a lead screw.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 5A and 5B, a motor body 2 having a lead screw 1a formed in a predetermined range of a rotary output shaft 1 and a moving nut screwed to the lead screw 1a. 3, a frame body 4 mounted on the motor body 2 to guide the movement of the moving nut 3 and through which the base portion 1b of the rotary output shaft 1 penetrates, and a radial bearing 5 for rotatably supporting the base portion 1b of the rotary output shaft 1. There is known a stepping motor M provided with
882).

The frame body 4 is a mounting plate 2 for the motor body 2.
A substantially U-shaped frame 4a fixed to a and a guide frame 4 installed between the opposing wall portions of the frame 4a.
b, the moving nut 3 moves on the lead screw 1a as the rotation output shaft 1 rotates while being guided by the guide frame 4b via the sliding member 6.

As shown in FIG. 6, the radial bearing 5 straddles the frame 4a and the mounting plate 2a, and is fitted or press-fitted into a support hole 2c formed in the mounting plate 2a to mount the mounting plate 2a.
a.

On the other hand, the tip of the rotary output shaft 1 is attached to the frame 4
A thrust bearing 7 held by a is rotatably supported via a steel ball 8. Further, the lead screw 1a of the rotary output shaft 1 is processed by a method such as a rolling process in which it is rolled on a die, and the processed end portion is a relief for escaping the meat (surplus metal part) swelled by the screw. The groove 1c is formed.

Further, such a stepping motor M
In applications where low noise and low vibration are particularly required (for example, video cameras), lubricating grease 9 is attached to the outer peripheral surface of the base portion 1b of the rotary output shaft 1.

[0007]

By the way, in the stepping motor M configured as described above, since the lubricating grease 9 is attached to the outer peripheral surface of the rotary output shaft 1,
In particular, when the rotary output shaft 1 is rotated in a low temperature state, the viscosity of the lubricating grease 9 is high, so that the startability, particularly the startability, deteriorates.

This is because the spread of the lubricating grease 9, that is, the radius of rotation R (see FIG. 6) of the viscous resistance from the axis of the rotary output shaft 1 to the resistance center of the lubricating grease 9 becomes large at the time of starting at a low temperature. Is.

The present invention has been made in view of the above circumstances, and provides a stepping motor capable of improving startability without impairing reduction of vibration noise caused by rotation of a rotary output shaft by use of lubricating grease. The purpose is to do.

[0010]

In order to achieve the object, the invention described in claim 1 is a rotary output shaft projecting from a motor body and having a lead screw formed thereon, and a rotary output shaft mounted on the motor body and rotating. A frame body through which a base portion of the output shaft penetrates, a moving nut that is screwed into the lead screw and is guided by the frame body to move on the lead screw, and provided across the frame body and the motor body. In a stepping motor including a radial bearing that rotatably supports the base of the rotary output shaft, an escape groove is formed on the outer peripheral surface of the rotary output shaft so that at least a part of the radial groove faces the radial bearing. The gist is that the escape groove is used as a grease reservoir for lubricating grease.

[0011]

In the above-mentioned structure according to claim 1,
The rotation output shaft that forms the lead screw is projected from the motor body, the frame body through which the base of the rotation output shaft penetrates is attached to the motor body, and the moving nut that is guided by the frame body and moves on the lead screw is the lead screw. A radial bearing, which is screwed and rotatably supports the base of the rotary output shaft, is provided so as to straddle the frame body and the motor body, and a clearance groove at least a part of which faces the radial bearing faces the rotary output shaft. It is formed on the outer peripheral surface of and the lubricating groove is provided in this clearance groove.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the stepping motor of the present invention will be described with reference to the drawings.

In FIGS. 1A and 1B, a stepping motor 10 includes a motor body 11 and a lead screw 1.
2a has a rotary output shaft 12, a frame body 13 fixed to the motor body 11, a moving nut 14 screwed to a lead screw 12a, and a radial bearing 15 rotatably supporting a base portion 12b of the rotary output shaft 12. .

The motor body 11 is a substantially cylindrical motor case 16 and a lid 1 fixed to one end of the motor case 16.
7, coil 1 provided on the inner wall surface of the motor case 16
8, a drive magnet 19 fixed to the base 12b of the rotary output shaft 12, and a mounting plate 20 fixed to the other end of the motor case 16. The drive magnet 19 faces the coil 18.

The frame body 13 is provided with a substantially U-shaped frame 13a fixed to the mounting plate 20 and a guide frame 13d installed between the opposing wall portions 13b and 13c of the frame 13a. Is guided by the guide frame 13d via the sliding member 21 and moves on the lead screw 12a as the rotary output shaft 12 rotates. A thrust bearing 22 is provided on the wall portion 13c of the frame 13a, and a protruding end of the rotary output shaft 12 is rotatably supported by the thrust bearing 22 via a steel ball 23.

The radial bearing 15 is, as shown in FIG.
It is provided so as to straddle the wall portion 13b of the frame 13a and the mounting plate 20, is inserted into the support hole 13e of the wall portion 13b, and is fitted or press-fitted into the support hole 20a formed in the mounting plate 20. Further, in the bearing peripheral surface 15a of the radial bearing 15, a portion corresponding to the support hole 20a, that is, a portion where the radial bearing 15 is fitted or press-fitted into the mounting plate 20, is deformed by the fitting or press-fitting. An escape hole 15b is formed to prevent this.

On the other hand, the lead screw 12a is processed by a method such as a rolling process in which it is rolled on a die, and the outer peripheral surface of the rotary output shaft 12 located at the processed end (screw groove end) is expanded by a screw. An escape groove 12c is formed for escaping the meat (excess metal portion).

The clearance groove 12c is formed so that at least a part thereof faces the radial bearing 15. That is, as shown in the figure, the radial bearing 15 may be partially overlapped with the radial bearing 15, or the entire clearance groove 12c may be positioned within the radial bearing 15. Lubrication grease 24 is attached to the escape groove 12c, and the rotation output shaft 12 is smoothly supported by the radial bearing 15 by the lubrication grease 24, and the generation of vibration noise accompanying the rotation of the rotation output shaft 12 is reduced. To be done.
Further, the escape groove 12c also plays a role of not hindering the rotation of the rotation output shaft 12 at the time of starting even if the lubricating grease 24 has a high viscous resistance at a low temperature.

That is, when the same amount of lubricating grease 24 as the conventional lubricating grease 9 is attached to the escape groove 12c, the radius of rotation r (of the viscous resistance from the axis of the rotary output shaft 12 to the resistance center of the lubricating grease 24) 2) can be made smaller than the turning radius R by the depth of the escape groove 12c,
The small rotation radius r improves the rotatability of the rotation output shaft 12 even when the viscosity is high at low temperatures.

In order to assemble the stepping motor 10 in the above construction, first, the mounting plate 20 and the motor case 16 are joined by spot welding or the like, and then the radial bearing 15 is laid over the mounting plate 20 and the frame body 13. To the radial bearing 15 by fitting or press fitting,
The moving nut 14, the sliding member 21, and the thrust bearing 22 are mounted on the frame body 13.

Next, the rotary output shaft 12 having the drive magnet 19 fixed to the base portion 12b is inserted from the motor body 11 side, the base portion 12b is supported by the bearing peripheral surface 15a of the radial bearing 15, and the thrust is passed through the steel ball 23. The bearing 22 is made to support the protruding end. At this time, the lead screw 12a
A moving nut 14 is screwed into the.

Then, the motor case 16 and the lid 17 are joined by spot welding or the like, and the lubricating grease 24 is attached to the escape groove 12c.

In the stepping motor 10 thus assembled, when a current is passed through the coil 18, the rotary output shaft 12 is rotated by the current flowing through the coil 18 and the magnetic force of the drive magnet 19.

At this time, a part of the escape groove 12c overlaps with the radial bearing 15 or the escape groove 12c is located in the radial bearing 15, so that the conventional escape groove 1
It is possible to bring the lead screw 12 closer to the motor body 11 than c, so that even if the rotation output shaft 12 and the conventional rotation output shaft 1 have the same shaft length,
It is possible to secure the movement allowable range of the moving nut 14 by a longer than the movement allowable range of the moving nut 3 by the conventional lead screw 1a.

When the rotary output shaft 12 is started, the radius of rotation r of the viscous resistance from the axis of the rotary output shaft 12 to the resistance center of the lubricating grease 24 becomes smaller due to the depth of the relief groove 12c. Since the rotation radius r is small, the rotation output shaft 12 starts to rotate smoothly even when the viscosity is high at low temperature, and the startability is improved.

By the way, the clearance groove 12c is formed as a necessary member when the lead screw 12a is formed by the rolling process, and is not newly formed as a special dedicated member. The processing cost of 12 does not rise so much.

Further, as shown in FIGS. 3 and 4, the radial bearing 15 can provide the same effect even if it is provided in the opposite direction as the radial bearing 25 having the same function.
Incidentally, in FIGS. 3 and 4, the same components as those of the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

That is, the radial bearing 25, like the radial bearing 15, has the wall portion 13b of the frame 13a and the mounting plate 20.
And is inserted into the support hole 20a formed in the mounting plate 20 and is fitted or press-fitted into the support hole 13e of the wall portion 13b. In addition, the bearing peripheral surface 25a of the radial bearing 25
Of the above, a portion corresponding to the support hole 13e, that is, a portion where the radial bearing 25 is fitted or press-fitted into the wall portion 13b,
An escape hole 25b is formed to prevent the radial bearing 25 from being deformed by this fitting or press fitting. The escape hole 25b
Faces the escape groove 12c, and the lubricating grease 24 is provided across the escape hole 25b and the escape groove 12c.
The clearance groove 12c is formed so that at least a part thereof faces the radial bearing 25. That is, as shown, the radial bearing 25 may be partially overlapped with the radial bearing 25.
The entire escape groove 12c may be formed in the inside of the groove 5.

[0029]

As explained above, in the stepping motor of the present invention, the clearance groove is formed on the outer peripheral surface of the rotary output shaft so that at least a part thereof faces the radial bearing, and By using the escape groove as the grease reservoir of the lubricating grease, the lubricating grease can improve the startability without impairing the reduction of the generation of vibration noise due to the rotation of the rotation output shaft.

[Brief description of drawings]

FIG. 1 shows a stepping motor of the present invention, (A) is a side view of the stepping motor, and (B) is a sectional view of the stepping motor.

FIG. 2 is likewise an enlarged cross-sectional view of a main part.

FIG. 3 shows a second embodiment of the stepping motor of the present invention, and is a sectional view of the stepping motor.

FIG. 4 is also an enlarged cross-sectional view of a main part.

FIG. 5 shows a conventional stepping motor, (A) is a side view of the stepping motor, and (B) is a sectional view of the stepping motor.

FIG. 6 is likewise an enlarged cross-sectional view of a main part.

[Explanation of symbols]

 10 ... Stepping motor 11 ... Motor body 12 ... Rotation output shaft 12a ... Lead screw 12b ... Base part 12c ... Escape groove 13 ... Frame body 14 ... Moving nut 15 ... Radial bearing 24 ... Lubrication grease

Claims (2)

[Claims] 1. A rotation output shaft protruding from a motor body and having a lead screw formed thereon, and a frame body mounted on the motor body and having a base portion of the rotation output shaft penetrating therethrough.
A moving nut that is screwed into the lead screw and is guided by the frame body to move on the lead screw, and is provided so as to extend over the frame body and the motor body and to allow the base of the rotation output shaft to rotate. In a stepping motor having a radial bearing to be supported, an escape groove is formed on the outer peripheral surface of the rotary output shaft so that at least a part of the escape groove faces the radial bearing, and the escape groove is filled with lubricating grease. A stepping motor characterized by a grease reservoir. 2. The stepping motor according to claim 1, wherein the clearance groove is a clearance groove formed by a rolled screw.