JP2558385Y2 - Stepping motor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized stepping motor, and more particularly to a stepping motor with reduced torque attenuation and noise during motor rotation.

[0002]

2. Description of the Related Art A so-called stepping motor is often used for a lens driving mechanism of an autofocus camera. Conventionally, as this kind of stepping motor, for example, the one shown in FIG. 4 or FIG. 5 is conventionally known.

FIG. 4 shows the structure of a standard stepping motor.
Shown in Reference numeral 1 denotes a stator including a pair of cylindrical yokes and a coil wound around these yokes. A space formed in the center of the stator 1 includes a rotating shaft 2 and a rotor 3 fixed around the rotating shaft 2. Rota assay product 4
Is inserted. One end of the rotating shaft 2 extends in the axial direction and is threaded around to form a lead screw 5. On the other hand, a leaf spring 6 for applying a preload to the other end of the rotating shaft 2 in the direction of one end of the rotating shaft 2 is fixed to the end face of the stator 1 on the other end side of the rotating shaft 2 by a method such as resistance welding.

Further, the stator 1 on the lead screw 5 side
One end of a flat plate 7 is fixedly abutted on the end surface of the plate 7, and a metal bearing 8 for rotatably supporting an intermediate portion between the rotary shaft 2 and the lead screw 5 is installed at the center of the plate 7. At the same time, one end of a bracket 9 extending in the tip direction of the lead screw 5 is abutted and fixed to the other end of the plate 7 by a method such as screwing.

A bearing member 10 is fixed to the leading end of the lead screw 5 of the bracket 9, and a mortar-shaped recess 1 is provided at a position facing the leading end of the lead screw 5 of the bearing member 10.
0a is formed. Then, the ball 11 is sandwiched between the concave portion 10a and the same mortar-shaped concave portion 5a formed on the end face of the lead screw 5, and the ball 11 is pressed from the concave portion 5a to the concave portion 10a by the action of the leaf spring 6. By doing so, the lead screw 5 is rotatably supported.

FIG. 5 shows a cross section of a concave portion 10a formed in the bearing member 10 in a U-shape.
This is an example in which the lead screw 5 is rotatably supported via a ball 11 disposed between the bottom surface of the lead screw 5 and the concave portion 5a on the end surface of the lead screw 5.

In each of the above stepping motors,
When the coil is energized, a magnetic pole is formed in the stator 1, and the action of the magnetic pole and the magnetic pole formed on the rotor 3 causes the rotor assay product 4 to rotate about the rotation axis 2. In this case, the ball 11 rotates together with the concave portion 5a by the contact pressure received from the concave portion 5a.

[0008]

In recent years, from the viewpoint of preventing noise generated between the recess 10a and the ball 11 during rotation of the motor, resin is frequently used as the material of the ball 11.
However, when the resin ball 11 is used, for example,
In the stepping motor having the structure shown in FIG.
Of the ball 11 and the recess 5a at the contact portion with the
The deformation of the ball 11 due to the contact pressure from
As a result, the contact area between the ball 1 and the recess 10a increases.
The frictional resistance between the motor 1 and the recess 10a increases, and the torque during motor rotation may be attenuated due to the increase in the resistance.

Further, the volume of the space S formed between the concave portion 10a and the ball 11 decreases as the contact area between the ball 11 and the concave portion 10a increases, and the inside of the space S becomes negative pressure with respect to the outside air pressure. As a result, the ball 11 is sucked into the concave portion 10a,
The rotation of the ball 11 sometimes stopped. In this case, new noise was generated at the contact portion between the non-rotating ball 11 and the rotating concave portion 5a.

On the other hand, in the stepping motor having the structure shown in FIG. 5, since the space S is not formed, the ball 11 is not sucked into the recess 10a. However, recess 1
Since the positioning of the ball 11 with respect to 0a is exclusively performed by pressing the ball 11 from the concave portion 5a, depending on the axial accuracy of the lead screw 5, a swing occurs in the motor rotation direction between the concave portion 10a and the ball 11, This causes a problem that noise and vibration are generated.
In particular, when used in an apparatus having a recording function such as a video camera, the influence of these noises was remarkable.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a rotating shaft and a cylindrical yoke provided around the rotating shaft and wound with a coil. And a bearing member that rotatably supports one end of the rotating shaft at its end face,
The bearing member is provided wherein one end of the end face and the opposite sliding pot-shaped recess is formed which Rutotomoni, a plurality of projections integrally extending radially along the radial direction from the center to the bottom of the recess
The projection supports the one end .

In this case, a mortar-shaped recess is formed in the end surface of the one end, and the rotating shaft is rotatably supported via a ball rotatably held between the recess and the recess of the bearing member. May be adopted.

[0013]

In the stepping motor of the action present invention, Rutotomoni sliding pot-shaped recess of the end face facing the rotation shaft of the motor to the bearing member is formed, extending radially along from the center to the bottom surface of the recess in the radial direction a plurality of protrusions are formed, this
Since the end face is supported by the projections , the contact area between the bearing member and the ball held between the end face or the end face and the bearing member is reduced.
Therefore, the frictional resistance generated between the bearing member and the end face or the ball when the motor rotates is reduced.

[0014]

Next, an embodiment of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a longitudinal sectional view of a bearing portion of a standard stepping motor showing one embodiment of the present invention. Since the present invention relates to a conventional stepping motor, particularly to an improvement of a bearing portion for rotatably supporting an end face of a lead screw, description of other portions of the stepping motor will be omitted.

In FIG. 1, reference numeral 20 denotes a bearing member fixed to the leading end of the lead screw 5 of the bracket 9, and a concave portion having a mortar-shaped bottom surface 21a is provided at a position facing the leading end of the lead screw 5 of the bearing member 20. 21 are formed. Here, the diameter of the recess 21 is slightly larger than the diameter of the lead screw 5.

As shown in FIGS. 2 and 3, a plurality of projections 21b are formed radially from the center of the bottom surface 21a in the radial direction and protrude toward the distal end of the lead screw 5 on the bottom surface 21a. I have. In the case of this embodiment, the protrusion 2
1b is gradually increasing its projection amount radially outward from the center of the bottom surface 21a forming the taper portion 21c, but the bottom surface 21
A flat portion 21d is formed on the plane without protruding from the plane formed by the circumference of a. In addition, six protrusions 21b are formed, the angle α between the adjacent protrusions 21b is 30 °, and the angle β between the tapered portions 21c and 21c of the opposed protrusions 21b is 90 °.

The ball 11 is sandwiched between the tapered portion 21c and the same mortar-shaped concave portion 5a formed on the end surface of the lead screw 5, and the ball 11 is tapered from the concave portion 5a by the action of a leaf spring (not shown). By pressing against the portion 21c, the lead screw 5
It is supported rotatably. As a material of the ball 11, for example, a hard ball such as SUJ2 or SUS, or a sintered product of a powder made of resin or ceramic is used.

When a coil (not shown) is energized, the lead screw 5 rotates around its axis. In this case, the ball 11 rotates together with the concave portion 5a by the contact pressure received from the concave portion 5a.

By the way, in the stepping motor of the present embodiment, the ball 11 has a tapered portion 21 on the bottom surface 21a.
c and the recess 5 a of the lead screw 5. That is, since the ball 11 and the bottom surface 21a do not come into contact with each other except for the tapered portion 21c, the contact area between the bottom surface 21a and the ball 11 is reduced. In the case of the present embodiment, since six protrusions 21b are formed and the angle α formed by the adjacent protrusions 21b is 30 °, the contact area between the bottom surface 21a and the ball 11 is smaller than that in the case without the protrusions 21b. 1/2
Becomes

Accordingly, the frictional resistance generated between the bottom surface 21a and the ball 11 during rotation of the motor is reduced, so that the torque attenuated during rotation of the motor due to the frictional resistance is suppressed and the wear of the ball 11 is reduced.

Since the space S formed between the bottom surface 21a and the ball 11 is open to the outside air through the space formed between the adjacent projections 21b, the resin ball 11 is used. However, even when the contact area between the ball 11 and the tapered portion 21c increases, the pressure in the space S is equal to the external pressure. Therefore, the rotation of the ball 11 is stopped by the suction of the ball 11 to the bottom surface 21a, and the ball 11
Noise is prevented from being generated at the contact portion between the groove and the concave portion 5a.

Further, lubricant such as grease is evenly distributed through the space formed between the adjacent projections 21b.
a, the rotation of the ball 11 is smooth, and even if a foreign object enters between the bottom surface 21a and the ball 11, the foreign object falls into the space.
There is also an effect that the smooth rotation of 1 is not hindered.

[0023]

As described above, in the stepping motor having the above structure, the bearing member rotatably supporting the end face of the rotating shaft, and the end face of the rotating shaft or between the end face and the bearing member. Since the contact area with the ball is reduced, the frictional resistance generated between the bearing member and the end face or the ball during rotation of the motor is reduced, and the attenuation of the torque due to the frictional resistance is suppressed, and the frictional resistance is reduced. Generation of noise due to the increase is prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a bearing portion of a stepping motor according to a first embodiment of the present invention.

FIG. 2 is a front view of the recess according to the first embodiment of the present invention as seen from the direction II.

FIG. 3 is a view showing a structure of a bottom surface according to the first embodiment of the present invention;

FIG. 4 is a longitudinal sectional view of a conventional stepping motor.

FIG. 5 is a longitudinal sectional view of a bearing portion of a conventional stepping motor.

[Explanation of symbols]

 Reference Signs List 1 stator 2 rotating shaft 3 rotor 4 rotor assay product 5 lead screw 5a, 10a, 21 recess 6 leaf spring 7 plate 8 metal bearing 9 bracket 10, 20 bearing member 11 ball 21a bottom surface 21b protrusion 21c taper portion 21d flat surface α adjacent Angle between projections β Angle between the opposite projection and the center of the bottom

Claims (2)

(57) [Scope of request for utility model registration] A rotating shaft, a rotor provided around the rotating shaft, a cylindrical yoke provided around the rotor at a distance from the rotor, and wound with a coil;
In the stepping motor comprising a bearing member for rotatably supporting one end of said rotary shaft at its end faces, the bearing member, sliding pot-shaped recess facing the end face of the one end is formed Rutotomoni, of the recess A plurality of projections are provided integrally on the bottom surface and extend radially from the center in the radial direction.
A stepping motor characterized in that the one end is supported by these projections . 2. A mortar-shaped concave portion is formed on an end surface of the one end, and the rotary shaft is rotatable via a ball rotatably held between the concave portion and the concave portion formed on the bearing member. A stepping motor characterized by being supported by a motor.