JP2002125358A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor which can suppress the acceleration of wearing of a column and has a column with high strength. SOLUTION: A column 31 has a shaft part 32, screwed onto a rotary shaft 16 and a retainer 33, retained by a rotation stopping part 20e of a motor housing 20 for suppressing the rotation and is moved linearly in the axial direction of the rotary shaft 16 according to the rotation of the rotary shaft 16. The shaft part 32 of the column 31 is made of resin, filled with fibers and the retainer 33 of the column 31 is made of unfilled resin and formed, so as to almost cover the protrusion 32a of the shaft part 32. The shaft part 32 and the retainer 33 are integrally molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly, to a column for converting a rotation output of a rotor of a stepping motor into an axial direction of a rotating shaft.

[0002]

2. Description of the Related Art As shown in FIG. 4, a stepping motor 1 includes a substantially inverted bowl-shaped motor case 2, and a bearing recess 2a is formed in the center of the upper inner surface. A part of the outer peripheral portion of the motor case 2 (the left side surface of the motor case 2 in FIG. 4) is cut away, and the lower portion is open.

[0003] A first stator core 3 as a stator is disposed around the upper inner side surface of the motor case 2. The first stator core 3 is a magnetic material, and includes an upper pole stator core 3a and a lower pole stator core 3b having a plurality of pole teeth, and the outer shape thereof is formed in an annular shape. A first coil sub-assembly 4 is arranged in a concave portion having a U-shaped cross section formed on the outer periphery of the first stator core 3.

The first coil sub-assembly 4 includes a first coil bobbin 5 and a first coil 6. More specifically, the first coil bobbin 5 is made of resin, and its outer shape is formed in an annular shape. The first coil 6 is wound around a U-shaped recess formed on the outer periphery of the first coil bobbin 5.

[0005] A second stator core 8 as a stator is disposed below the first stator core 3 with a yoke 7 interposed therebetween and coaxially with the first stator core 3. The second stator core 8 is a magnetic material, and includes an upper pole stator core 8a and a lower pole stator core 8b having a plurality of pole teeth, and the outer shape thereof is formed in an annular shape. A second coil sub-assembly 9 is arranged in a concave portion having a U-shaped cross section formed on the outer periphery of the first stator core 3.

The second coil sub-assembly 9 includes a second coil bobbin 10 and a second coil 11. More specifically, the second coil bobbin 10 is made of resin, and its outer shape is formed in an annular shape. The second coil 11 is wound around a U-shaped recess formed on the outer periphery of the second coil bobbin 10.

A connector housing 12 is attached to a part of the outer peripheral portion of the motor case 2 which is partially cut away (the left side of the motor case 2 in FIG. 4).
A plurality of connection terminals 13 are provided in the connector housing 12, and the connection terminals 13 are connected to the first coil 6 and the second coil 6.
It is connected to the coil 11 (not shown). A drive device (not shown) is connected to the connection terminal 13, and a pulse signal is supplied from the drive device to the first coil 6 and the second coil 11 via the connection terminal 13.

An upper bearing 14 is provided in the bearing recess 2a of the motor case 2, and a rotor assembly 15 is supported by the upper bearing 14. The rotor assembly 15 includes a rotor shaft 16 as a rotation axis and a rotor section 17.

The rotor shaft 16 is formed in a substantially columnar shape, the center line of which is aligned with the center lines of the first stator core 3 and the second stator core 8, and the upper end of the rotor shaft 16 is connected to the upper bearing 14 It is pivoted on. A screw portion 16a having a male screw as a screw screw is formed at a lower portion of the rotor shaft 16. The rotor portion 17 is fixed to an upper portion of the rotor shaft 16.

The rotor section 17 has a support section 17a and a cylindrical section 17b as a rotor magnet. Support part 1
7a is formed in a substantially disk shape, and is fixed to the rotor shaft 16 that penetrates a central portion thereof. Also, the cylindrical portion 17
b is formed in a cylindrical shape, and the support portion 17a is formed on the inner peripheral surface thereof.
Is fixed at the outer peripheral end.

The cylindrical portion 17b is provided in the first stator core 3
And a space is provided inside the second stator core 8 with the inner peripheral surface thereof. The cylindrical portion 17b is formed of a magnetic material, for example, a thermoplastic synthetic resin (plastic magnet) containing ferrite as a magnetic material.

As shown in FIG. 5, a stopper surface 18 as a stopper is formed on the lower surface of the cylindrical portion 17b. Magnetic poles N and S having the same width in the circumferential direction are alternately magnetized at equal angular intervals on the outer peripheral surface of the cylindrical portion 17b.

A motor housing 20 made of a synthetic resin is attached to a lower portion of the motor case 2. At the upper part of the motor housing 20, a support cylinder 20a disposed in the cylindrical portion 17b is formed to extend upward. Note that there is a space between the outer peripheral surface of the support cylinder 20a and the inner peripheral surface of the cylindrical portion 17b. And the support cylinder 2
A lower bearing 19 is fixed to the upper inner surface of the upper shaft 0a, and the center of the rotor shaft 16 is rotatably supported by the support cylinder 20a via the lower bearing 19.

An annular groove 20b is formed in the motor housing 20 on the outer surface of the base end portion of the support cylinder 20a along the support cylinder 20a. The lower end of the cylindrical portion 17b fits into the annular groove 20b.

An output side recess 20c which is open downward is formed in the lower portion of the motor housing 20. A communication hole 20d communicating with the inside of the support cylinder 20a is formed in the output side recess 20c, and the rotor shaft 16 protrudes into the output side recess 20c via the communication hole 20d. As shown in FIG. 6, a plurality of sets (four sets in the figure) of rotation stopping portions 20e are formed on the inner surface of the output side recess 20c so as to extend downward.

Each of the rotation stopping portions 20e is provided with a wall plate 20.
f and the wall plate 20g, and the wall plate 20f and the wall plate 20g are formed apart from each other by a predetermined distance so as to have a space therebetween. Further, as shown in FIG. 4, the output side recess 2 between the wall plate 20f and the wall plate 20g.
An inner surface of Oc is cut out to form an introduction hole 20h penetrating through the annular groove 20b. In addition, the introduction hole 20h
Are formed at four locations at 90-degree intervals corresponding to the positions where the four sets of rotation stoppers 20e are formed.

The wall plate 20 in each of the rotation stopping portions 20e
The column 21 is screwed into the threaded portion 16a of the rotor shaft 16 between f and 20g. That is, as shown in FIG. 4, a shaft hole 21a is formed in the center of the column 21, and a female screw is formed on the inner peripheral surface of the shaft hole 21a.

As shown in FIG. 6, a plurality of (four in the drawing) engaging pieces 21b are provided on the outer peripheral surface of the lower part of the column 21.
Project from the outer peripheral surface of the column 21 and extend at equal angular intervals in the circumferential direction of the column 21. Each of the engaging pieces 21b is connected to the wall plate 20 of the four sets of the rotation stoppers 20e.
f and 20 g, respectively.
Therefore, when the rotor shaft 16 rotates, each engagement piece 2
1b is a wall plate 20f, 20g in each rotation stopping portion 20e.
, The column 21 moves in the axial direction without rotating.

One of the four engaging pieces 21b has an abutting portion 21c extending from the upper surface thereof. Accordingly, the column 21 moves upward in FIG. 4 with the rotation of the rotor shaft 16, and when the upper portion of the column 21 passes through the communication hole 20d and is located in the cylindrical portion 17b, the engagement having the contact portion 21c is established. The corresponding contact portion 21c of the piece 21b is guided to the annular groove 20b through the introduction hole 20h.

As shown in FIG. 5, a stopper surface 18 formed at the lower end of the cylindrical portion 17b is engaged with the contact portion 21c guided by the annular groove 20b. The position of the column 21 and the position of the rotor assembly 15 in this state are set as the starting points.

When the column 21 and the rotor assembly 15 are at the starting point, the first coil 6 and the second coil 11
When a pulse signal is input to the rotor assembly 15 and the rotor assembly 15 rotates clockwise, for example, the rotation of the column 21 screwed to the male screw of the rotor shaft 16 is restricted by the rotation stopper 20e (wall plate 20f) and moves downward. I do.

On the other hand, when the column 21 is at a position distant from the rotor assembly 15 and the rotor assembly 15 rotates left, the rotation is regulated by the rotation stopping portion 20e (wall plate 20g) and moves upward. Then, the engagement piece 21
The contact portion 21c of b contacts the stopper surface 18 to stop the rotation of the rotor assembly 15, and the column 21 and the rotor assembly 15 are again located at the starting point.

[0023]

By the way, in recent years, as the output of the motor increases, it is required to increase the strength of the column 21 for converting the rotational output of the rotor in the axial direction of the rotating shaft of the rotor. For this reason, the column 21 which is axially moved by being screwed into the rotor shaft 16 (male screw).
For example, a method of increasing the strength of the inner peripheral surface (female screw) of the shaft hole 21a in the column 21 by adding a reinforcing fiber such as a glass fiber has been proposed.

However, when the strength of the column 21 is increased by such a method, the engagement piece 21 of the column 21 is increased.
The friction between the b and the rotation stopper 20e (wall plates 20f, 20g) becomes high, and the wear of the engagement piece 21b and the rotation stopper 20e (wall plates 20f, 20g) is promoted.

Therefore, a means has been proposed in which the shaft hole 21a to be screwed to the rotor shaft 16 and the engaging piece 21b to be engaged with the rotation stopper 20e are separately manufactured, and the column 21 is composed of two articles. ing. However, this method results in an increase in manufacturing costs due to an increase in the number of parts and an increase in the number of assembly steps. Further, when the position of the engagement piece 21b with respect to the shaft hole 21a varies at the time of assembly, the engagement piece 21b and the rotation stopper 20e (the wall plates 20f and 2) are not provided.
0 g).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a stepping motor having a high strength column, which suppresses the promotion of wear in the column. Is to do.

[0027]

Means for Solving the Problems In order to solve the above problems, an invention according to claim 1 includes a stator, a rotor disposed inside the stator and rotated by the stator, A rotation shaft fixed to the rotor and rotating with the rotor, a motor housing rotatably supporting the rotation shaft, a shaft screwed to a screw screw formed on the rotation shaft, and a rotation stopping portion of the motor housing; And a column that has an engagement piece that is engaged with the rotation thereof and is inhibited from rotating, and a column that linearly moves in the axial direction of the rotation shaft based on the rotation of the rotation shaft. The shaft portion is formed of a resin to which fibers are added, and the engagement piece is formed of a resin to which fibers are not added.

According to a second aspect of the present invention, in the stepping motor according to the first aspect, the column is formed by integrally molding the shaft portion and the engaging piece. According to a third aspect of the present invention, in the stepping motor according to any one of the first to second aspects, the engagement pieces project from an outer peripheral surface of the shaft portion, and are equiangularly spaced in a circumferential direction of the shaft portion. And formed parallel to the axis of the shaft.

The invention described in claim 4 is the invention according to claims 1 to 3
In the stepping motor according to any one of the above, the shaft portion protrudes from the outer peripheral surface of the shaft portion, is formed at equal angular intervals in the circumferential direction of the shaft portion, and with respect to the axis of the shaft portion. The projecting pieces formed in parallel are integrally formed.

According to a fifth aspect of the present invention, in the stepping motor according to the fourth aspect, the engaging piece is formed so as to cover the projecting piece, and the projecting piece is formed with the engaging piece. In this state, convex portions protruding from both ends in the axial direction of the engagement piece are formed.

The invention according to claim 6 is the invention according to claims 1 to 5
In the stepping motor according to any one of the above, the resin forming the engagement piece is the same as the resin forming the shaft portion.

[0032] The invention according to claim 7 is the invention according to claims 1 to 6.
In the stepping motor according to any one of the above, the rotor is provided with a stopper that engages with a contact portion of the column and stops the rotor at a predetermined rotation position, and the contact portion is formed. The engagement piece is formed in a plate shape that covers the shaft portion, and one surface of the plate surface is formed along a ray passing through the center of the axis of the shaft portion.

[0033] The invention according to claim 8 is the invention according to claims 1 to 7.
The method of molding a column according to any one of the above, wherein after forming the shaft portion with a resin to which fibers are added, holding the convex portion, using the same resin as the shaft portion without adding fibers. The engaging piece was formed, and the shaft portion and the engaging piece were integrally formed.

According to the first aspect of the present invention, the shaft portion of the column that is screwed to the screw screw formed on the rotating shaft of the rotor is formed of resin to which fibers are added, thereby improving the strength of the column. Can be raised. In addition, since the engaging piece of the column that engages with the motor housing and makes the column unrotatable is formed of a resin to which fiber is not added, it is necessary to suppress friction between the engaging piece and the rotation stopping portion of the motor housing. Can be.

According to the second aspect of the present invention, since the shaft portion of the column and the engaging piece are integrally formed, the position of the engaging piece with respect to the shaft portion is set with high precision, thereby preventing rotation. It is possible to suppress friction between the parts and to prevent an increase in manufacturing cost.

According to the third aspect of the present invention, since the engagement piece of the column is formed parallel to the axis of the shaft, the engagement position with the stopper of the rotor can be set with high accuracy. That is, the starting origin position of the motor can be set with high accuracy.

According to the fourth and fifth aspects of the present invention, the engaging piece of the column is formed so as to cover the projecting piece formed of resin to which fibers are added. Therefore, the engagement piece can be reinforced while maintaining the effect of suppressing wear on the engagement piece. Further, by forming the protruding piece, the deformation of the shaft portion can be suppressed by the molding pressure at the time of molding the engaging piece.

According to the sixth aspect of the present invention, since the resin used for the shaft portion and the engagement piece are the same, the shaft portion and the engagement piece can be securely brought into close contact with each other. In addition, by using the same resin, the thermal expansion coefficient can be made substantially the same, and a column having excellent thermal characteristics can be obtained.

According to the seventh aspect of the present invention, in particular, in the motor of the right specification in which the stopper surface of the rotor portion engages with the flat plate surface passing through the center of the axis, the starting origin position can be made highly accurate. it can.

According to the eighth aspect of the present invention, since the engaging piece is formed while holding the projection, the position of the engaging piece with respect to the protruding piece can be easily determined.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the configuration of the column 21 in the conventional stepping motor 1 is changed, and other identical components are given the same names and the same reference numerals.

In the motor case 2 of the stepping motor 1, first and second stator cores 3, 8 as stators made of a magnetic material are disposed vertically and coaxially via a yoke 7. . The first stator core 3 includes an upper pole stator core 3a having a plurality of pole teeth and a lower pole stator core 3b, and the outer shape is formed in an annular shape. Similarly, the second stator core 8 includes an upper pole stator core 8a having a plurality of pole teeth and a lower pole stator core 8b, and the outer shape thereof is formed in an annular shape.

First and second coil sub-assemblies 4 and 9 are provided in concave portions having a U-shaped cross section formed on the outer periphery of the first and second stator cores 3 and 8, respectively. The first coil sub-assembly 4 includes an annular first coil bobbin 5 made of resin and a first coil 6 wound around the outer periphery of the first coil bobbin 5. Similarly, the second coil sub-assembly 9 includes an annular second coil bobbin 10 made of resin and a second coil 11 wound around the outer periphery of the second coil bobbin 10.

The first coil 6 and the second coil 1 are mounted on the connector housing 12 attached to the motor case 2.
1 is provided with a connection terminal 13. And
When a pulse signal is supplied from a driving device (not shown) to the first and second coils 6, 11 via the connection terminal 13, the first and second coils 6, 11 are connected to the first and second coils 6, 11, respectively. N poles or S poles alternating with the plurality of pole teeth of the stator cores 3 and 8 are generated.

The first and second stator cores 3, 8
A rotor assembly 15 including a rotor shaft 16 as a rotation axis and a rotor portion 17 fixed to the rotor shaft 16 is disposed at the center of the rotor shaft 16.

The rotor section 17 comprises a support section 17a and a cylindrical section 17b as a rotor magnet.
b, magnetic poles N and S having the same width in the circumferential direction
Are alternately magnetized at equal angular intervals. Also, the cylindrical portion 17
A stopper surface 18 as a stopper is formed on the lower surface of b. The cylindrical portion 17b is a magnetic material, and is formed of, for example, a thermoplastic synthetic resin (plastic magnet) containing ferrite as the magnetic material.

A motor housing 20 made of a synthetic resin is attached to a lower portion of the motor case 2, and a support cylinder 20a provided in the cylindrical portion 17b extends upward at an upper portion of the motor housing 20. It has been formed.

The upper end of the rotor shaft 16 is rotatably supported by the upper bearing 14 in the upper part of the motor case 2, and the center of the rotor shaft 16 is on the inner surface of the upper part of the support cylinder 20 a inside the cylindrical part 17 b. It is rotatably supported by the lower bearing 19 to be fixed. The upper portion of the rotor shaft 16 is fixed to a support portion 17a formed on the rotor portion 17. That is, the rotor shaft 1
6 rotates integrally with the rotor unit 17. At the lower end of the rotor shaft 16, a screw portion 16a having a male screw as a screw screw is formed.

An annular groove 20b is formed along the support cylinder 20a in the motor housing 20 on the outer surface of the base end of the support cylinder 20a. And this annular groove 20b
The lower end of the cylindrical portion 17b fits inside.

An output side recess 20c which is opened downward is formed in the lower portion of the motor housing 20. A communication hole 20d communicating with the inside of the support cylinder 20a is formed in the output side recess 20c, and the rotor shaft 16 protrudes into the output side recess 20c via the communication hole 20d. As shown in FIG. 2, a plurality of sets (four sets in the figure) of rotation stopping portions 20e are formed to extend downward on the inner surface of the output side recess 20c.

Each of the rotation stoppers 20e is provided on the wall plate 20.
f and the wall plate 20g, and the wall plate 20f and the wall plate 20g are formed apart from each other by a predetermined distance so as to have a space therebetween. As shown in FIG. 1, the output side recess 2 between the wall plate 20f and the wall plate 20g.
An inner surface of Oc is cut out to form an introduction hole 20h penetrating through the annular groove 20b. In addition, the introduction hole 20h
Are formed at four places at 90-degree intervals corresponding to the positions where the four rotation stoppers 20e are formed.

As shown in FIG. 1, each of the rotation stopping portions 20
The column 31 is screwed into the threaded portion 16a of the rotor shaft 16 between the wall plates 20f and 20g in e. A shaft hole 31a is formed at the center of the column 31, and a female screw is formed on the inner peripheral surface of the shaft hole 31a. The screw portion 16 a is screwed into the shaft hole 31 a of the column 31, and the upper portion of the column 31 is located in the support cylinder 20 a of the motor housing 20.

The column 31 includes a shaft portion 32 having the shaft hole 31a and an engagement piece 33. Shaft 3
As shown in FIG. 3, a plurality (4 in FIG.
The projections 32a protrude from the outer peripheral surface of the shaft portion 32 in parallel with its axis, and extend at equal angular intervals in the circumferential direction of the shaft portion 32. As shown in FIG. 3, the protrusion 32a extends in the axial direction at the upper end and the lower end of the protrusion 32a.
b is formed.

The engagement piece 33 is formed in a flat plate shape so as to substantially cover the outside of the protruding piece 32 a, and one surface of the flat plate surface is formed along a ray passing through the center of the axis of the shaft portion 32. . One of the four protruding pieces 32a is formed such that its upper surface is higher than the upper surface of the other protruding piece 32a, and an engaging piece formed at the position of the protruding piece 32a. As shown in FIG. 1, the upper portion of 33 is extended beyond the other engaging pieces 33 to form a contact portion 33 a.

In order to form the column 31 as described above, first, the shaft 32 having the protruding pieces 32a and the protruding parts 32b is made of a synthetic resin, for example, PPS (Poly Phenylene Sulphate).
fide) and the like. Glass fiber as a fiber is added to the synthetic resin forming the shaft portion 32. That is, the shaft portion 32 is formed of a synthetic resin reinforced with glass fiber.

Next, after the shaft portion 32 is formed, the engagement piece 33 is formed so as to substantially cover the outside of the shaft portion 32 as described above. The engagement piece 33 is formed of the same synthetic resin as the synthetic resin forming the shaft portion 32, and no glass fiber is added to the synthetic resin. That is, in the column 31, after forming the shaft portion 32, the engaging piece 33 is formed of the same synthetic resin as the shaft portion 32 which is not reinforced by glass fiber, and the column 31 is integrally formed.

When the engagement piece 33 is formed, the projection 32b
Is held in a concave portion (not shown) provided in the molding die of the engaging piece 33, the position of the engaging piece 33 with respect to each protruding piece 32a is determined, and the deformation of the protruding piece 32a due to the molding pressure is controlled. To prevent it.

Then, the column 3 configured as described above
1, the four engaging pieces 33 are disposed between the wall plates 20f and 20g of the rotation stopper 20e, as shown in FIG. Therefore, when the rotor shaft 16 rotates, each engagement piece 33 engages with each rotation stopper 20e, and the column 31 moves in the axial direction without rotating. When the column 31 moves upward in FIG. 1 with the rotation of the rotor shaft 16 and the upper portion of the column 31 passes through the communication hole 20d and is located in the cylindrical portion 17b, the engagement having the contact portion 33a is established. The corresponding contact portion 33a of the piece 33 is guided to the annular groove 20b through the introduction hole 20h.

The stopper portion 18 formed at the lower end of the cylindrical portion 17b is engaged with the contact portion 33a guided by the annular groove 20b. The column 31 in this state
And the position of the rotor assembly 15 are set as the starting origin.

Next, the operation of the stepping motor configured as described above will be described. Now, when the column 31 and the rotor assembly 15 are at the starting origin, a pulse signal is input to the first coil 6 and the second coil 11 and, for example, when the rotor assembly 15 rotates clockwise, it is screwed into the external thread of the rotor shaft 16. The column 31 is rotated by the rotation stopper 20e.
The rotation is regulated by the (wall plate 20f), and moves downward.

On the other hand, when the column 31 is at a position away from the rotor assembly 15 and the rotor assembly 15 rotates counterclockwise, the column 31 is rotated by the rotation stopper 20e (the wall plate 20).
The rotation is regulated by g), and moves upward. Then, the contact portion 33a of the engaging piece 33 contacts the stopper surface 18 to stop the rotation of the rotor assembly 15, and the column 31
And the rotor assembly 15 is again located at the starting point.

Therefore, the following features can be obtained in the stepping motor configured as described above. (1) The shaft 32 of the column 31 screwed to the rotor shaft 16 was formed of a synthetic resin to which glass fiber was added. With such a configuration, the strength of the shaft portion 32 on which the female screw is formed can be increased. On the other hand, the shaft 3
Since the engaging piece 33 formed on each of the projecting pieces 32a of No. 2 was formed of a synthetic resin to which glass fiber was not added,
Similarly, friction between the rotation stoppers 20e formed of synthetic resin can be suppressed.

(2) The column 31 includes the shaft portion 32 and the engagement piece 3
3 is integrally molded, so that an increase in manufacturing cost can be prevented. In addition, since the step of assembling the shaft portion 32 and the engagement piece 33 is unnecessary, there is no displacement of the engagement piece 33 with respect to the shaft portion 32 during the assembly.

(3) The engaging piece 33 is connected to the projecting piece 32a of the shaft 32.
Are formed so as to cover almost all of them, and a contact portion 33a is provided by extending an upper surface of any one of the engagement pieces 33, so that the contact portion 33a is provided below the cylindrical portion 17b. It can be reliably engaged with the formed stopper surface 18. That is, the accuracy of the motor starting origin position can be improved. In the present embodiment, the stopper surface 18 engages with the flat surface of the engagement piece 33 on the surface formed along the radiation passing through the center of the axis of the shaft portion 32. , The accuracy of the starting origin position can be improved.

(4) The projecting piece 32 a is attached to the shaft 32 of the column 31.
The deformation of the female screw formed on the shaft portion 32 due to the molding pressure during the formation of the engagement piece 33 can be suppressed.

(5) Each engaging piece 33 of the column 31 was formed so as to cover only each protruding piece 32a formed of resin to which fiber was added. Therefore, the engagement piece 33 can be reinforced while maintaining the effect of suppressing the wear on the engagement piece 33.

(6) Each protruding piece 32a is formed with convex portions 32b at both ends in the axial direction, and each engaging piece 33 is
The engaging piece 33 was formed by holding the convex portion 32b in a concave portion (not shown) of the molding die. Therefore, it is possible to easily position the formation position of the engagement piece 33 with respect to the protruding piece 32a, and to suppress the deformation of the female screw formed on the shaft portion 32 by the molding pressure when the engagement piece 33 is formed. it can.

(7) The synthetic resin forming the engagement piece 33 is
It was the same as the resin forming the shaft portion 32. Therefore, the shaft 3
The degree of close contact between 2 and the engagement piece 33 can be increased. or,
Since the thermal expansion coefficients of the shaft portion 32 and the engagement piece 33 can be substantially the same, the column 31 having excellent cooling / heating characteristics can be obtained.

This embodiment may be embodied with the following modifications. -The fiber added to the synthetic resin forming the shaft portion 32 is not limited to glass fiber, and may be another fiber.

A female screw may be formed on the rotor shaft 16. In the case of such a configuration, the shaft portion 3 of the column 31
2 is formed with a male screw to be screwed with the female screw. The shaft portion 32 of the column 31 is provided with four protrusions 32a on the outer peripheral surface thereof at equal angular intervals, and the same number (four) of the engagement pieces 33 are formed at the positions of the protrusions 32a. The engagement pieces 33 may be formed in an arbitrary number. in this case,
The same number of protrusions 32a and engagement pieces 33 are formed.

Although the engagement piece 33 is formed in a flat plate shape, the width is not limited to a flat plate shape but may be changed. In the case of such a configuration, the rotation stopper 20e is provided with the wall plates 20f,
It is configured by changing the interval of 20 g. Even with such a configuration, the same features as those described in the above embodiment can be obtained.

[0072]

As described above, according to the present invention, it is possible to provide a stepping motor including a column having high strength while suppressing the promotion of wear in the column.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a stepping motor according to an embodiment.

FIG. 2 is a bottom view showing the same stepping motor.

FIG. 3 is a bottom view showing the same column.

FIG. 4 is a sectional view showing a conventional stepping motor.

FIG. 5 is a front view showing the rotor portion and the column when the contact portion is engaged with a stopper surface.

FIG. 6 is a bottom view showing the same stepping motor.

[Explanation of symbols]

3, 8 ... 1st stator core and 2nd stator core as a stator, 15 ... rotor assembly as a rotor, 1
Reference numeral 6 denotes a rotor shaft as a rotating shaft, 17b a cylindrical portion as a rotor magnet, 18 a stopper surface as a stopper, 20 a motor housing, 31 a column, 32 a shaft, 33 an engagement piece, and 33a a column. Abutment as part.

Claims (8)

[Claims] A stator (3, 8) and a stator (3, 8) disposed inside the stator (3, 8).
Rotor (17) and its rotor (17)
A rotating shaft fixed to the rotor and rotating together with the rotor, a motor housing rotatably supporting the rotating shaft, and a screw screw formed on the rotating shaft. An engagement piece (33) that is engaged with the shaft (32) screwed to the (16a) and the rotation stopper (20e) of the motor housing (20) to prevent rotation.
And a column (31) that linearly moves in the axial direction of the rotary shaft (16) based on the rotation of the rotary shaft (16), wherein the column (31) includes: (32) is formed of resin to which fibers are added,
A stepping motor, wherein the engagement piece (33) is formed of a resin to which fibers are not added. 2. The stepping motor according to claim 1, wherein the column (31) is formed by integrally molding the shaft portion (32) and the engagement piece (33). Stepper motor. 3. The stepping motor according to claim 1, wherein the engagement piece (33) protrudes from an outer peripheral surface of the shaft portion (32), and the circumference of the shaft portion (32). A stepping motor formed at equal angular intervals in the direction and formed parallel to the axis of the shaft portion (32). 4. The stepping motor according to claim 1, wherein the shaft portion (32) protrudes from an outer peripheral surface of the shaft portion (32), and the circumference of the shaft portion (32). A stepping motor characterized by being formed at equal angular intervals in the direction and integrally formed with a protruding piece (32a) formed in parallel with the axis of the shaft portion (32). 5. The stepping motor according to claim 4, wherein the engaging piece (33) is formed so as to cover the projecting piece (32a), and the projecting piece (32a) is provided with the engaging piece (32). 3
A stepping motor characterized in that a projection (32b) projecting from both ends in the axial direction of the engagement piece (33) is formed in a state where 3) is formed. 6. The stepping motor according to claim 1, wherein the resin forming the engagement piece (33) is formed of a resin.
2) A stepping motor characterized in that it is the same as the resin forming step 2). 7. The stepping motor according to claim 1, wherein the rotor (17) is engaged with a contact portion (33a) of the column (31). A stopper (18) for stopping the shaft at a predetermined rotation position is formed, and the engaging piece (33) in which the contact portion (33a) is formed is formed in a flat plate shape covering the shaft portion (32), A stepping motor characterized in that one surface of the flat surface is formed along a ray passing through the center of the axis of the shaft portion (32). 8. The method for forming a column according to claim 1, wherein the shaft (32) is formed of a resin to which fibers are added, and then the protrusion (32b) is held. The engaging piece (33) is made of the same resin as the shaft (32) to which no fiber is added.
Wherein the shaft portion (32) and the engaging piece (33) are integrally formed.