JP3399499B2 - Stepping motor - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stepping motor.

[0002]

2. Description of the Related Art For example, a hybrid type stepping motor is used for paper feeding of a printer or a copying machine. This stepping motor is rotatable by a stator composed of a stator core and windings applied to the stator core, a pair of brackets arranged at both ends of the stator, a pair of bearings fixed to each bracket, and each bearing. And a rotor supported by. The stator core is sandwiched between the pair of brackets, and these are fixed at a plurality of points with bolts and nuts.

In this case, conventionally, a bracket made of aluminum die cast has been used, and the aluminum die cast is cut to improve the coaxiality.

For this reason, there is a problem in that it takes time to process the bracket and the manufacturing cost is high.

Therefore, as a method that is easy to manufacture, a method of manufacturing a bracket by pressing a metal plate has been proposed. In this case, however, noise generated from the motor is lower than that of the die-cast one. There is a big problem.

Moreover, compared with the die cast one,
Since the strength is low, when the bracket is fixed with screws, the stress due to the tightening is concentrated in the central part of the bracket, which displaces (deforms) particularly in the central part of the bracket, impairing the parallelism of the bracket and Is tilted or is out of position. As a result, the coaxiality between the rotating shaft, the bearing and the stator core is reduced. Therefore, the rotor may not be installed or the rotor may not rotate smoothly.

It is possible to increase the strength by increasing the thickness of the metal plate, but in this case, the workability deteriorates,
Its advantages are diminished.

It is also conceivable to form reinforcing ribs on the bracket without changing the thickness of the metal plate, but noise and vibration from the motor, displacement of the central portion of the bracket due to screw tightening, and The relationship with the rib forming pattern has not been clarified at all.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stepping motor which has low noise and vibration and high coaxiality.

[0010]

In order to solve the problems] to achieve such a purpose
For this reason, the present invention has a rectangular shape with chamfers at each corner.
With a stator and a square shape with chamfers at each corner,
Opening is formed in the center and multiple screws are attached to the outer periphery
A base portion having a hole for use, and the base portion provided upright to the base portion.
Side walls and attached to both ends of the stator, respectively.
Pair of brackets and the opening of the base of each bracket
A pair of bearings fixed inside the stator and the stator;
It is inserted inside and is rotatably supported by both bearings.
A stepping motor having a rotor
At least one of the two brackets has a base
And an annular first rib formed along the outer circumference
And connect each side wall of the square shape
Note Connected to the first rib and passing near the opening
Along with it, form a straight line so that the opposing ones are parallel.
Formed second ribs.

(1) A stator, a base portion having an opening formed in a central portion and a plurality of screw holes formed in an outer peripheral portion, and a side wall bent with respect to the base portion, A pair of brackets attached to both ends of the stator, a pair of bearings fixed respectively in the openings of the base of the brackets, and inserted inside the stator,
A stepping motor having a rotor rotatably supported by the bearings, wherein at least one of the brackets has at its base a first rib surrounding the opening, and the first rib. A stepping motor having a second rib connecting the side wall.

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The stepping motor of the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 is an exploded perspective view showing an embodiment of the stepping motor of the present invention, FIG. 2 is a sectional view of the stepping motor shown in FIG. 1, and FIG. 3 shows a structure of a bracket of the stepping motor shown in FIG. 4 is a plan view of the bracket shown in FIG. 3, FIG. 5 is a sectional view taken along the line AA of FIG. 4, FIG. 6 is a front view of the bracket shown in FIG.
Is a rear view of the bracket shown in FIG. 3, FIG. 8 is a cross-sectional view showing the first rib of the bracket shown in FIG. 3 and its vicinity, and FIG. 9 is a perspective view showing the configuration of the bracket of the stepping motor shown in FIG. 10 and 11 are plan views showing the structure of the stator core of the stepping motor shown in FIG.

As shown in FIG. 1 and FIG. 2, the stepping motor 1 of this embodiment is a hybrid type stepping motor, and includes a stator 7 and a first bracket (hereinafter, simply referred to as a bracket) attached to one end of the stator 7. "bracket"
5) and a second bracket (hereinafter simply referred to as “bracket”) 6 attached to the other end, a bearing 3 fixed to a base portion (bottom portion) 51 of the bracket 5 and a base portion (top portion) of the bracket 6. Bearing 4 fixed to 61,
The rotor 14 is inserted inside the stator 7 and is rotatably supported by the bearings 3 and 4.

Each of the bearings 3 and 4 is a slide bearing made of a sintered body.

The rotor 14 includes a rotary shaft 15 and a rotary shaft 15
Disc-shaped (annular plate-shaped) permanent magnet 16 installed on the outer circumference of
And a rotor core 17 joined to one end of the permanent magnet 16 and a rotor core 18 joined to the other end.

In this case, the rotary shaft 15, the permanent magnets 16,
With the rotor cores 17 and 18, the rotary shaft 15 is press-fitted into the inner cavities of the permanent magnet 16 and the rotor cores 17 and 18, or the rotary shaft 15 is inserted (fitted) into the inner cavities.
However, they are fixed by welding or adhering with an adhesive.

As the permanent magnet 16, a magnet having excellent magnetic properties is used. For example, a rare earth magnet (for example, Sm-Co magnet) containing a rare earth element and a transition metal as basic components, or a rare earth element and a transition metal. A rare earth magnet (eg, Nd-Fe-B based magnet) containing as a basic component boron and boron is preferably used. The form (type) of the permanent magnet 16 may be any one such as a bond magnet, a sintered magnet, and a cast magnet.

The rotor cores 17 and 18 are respectively
It is composed of a plurality of laminated steel plates (metal plates).

On the outer peripheral side surfaces of the rotor cores 17 and 18, a plurality of tooth poles 171 and 181 are arranged in parallel along the circumferential direction. In this case, the rotor cores 17 and 18 are displaced by a half pitch, that is,
The tooth pole 181 is arranged so as to be located between the adjacent tooth poles 171 and 171.

Although not shown, these rotor cores 17,
The permanent magnet 16 and the permanent magnet 16 may be molded with resin, leaving the tips of the tooth poles 171 and 181.

A pulley 2 is fitted in the tip of the rotary shaft 15 (upper end in FIGS. 1 and 2).

Further, three washers 19 are inserted between the bearing 3 and the rotor core 17, and similarly, three washers 19 are inserted between the bearing 4 and the rotor core 18.
Has been inserted.

The stator 7 includes a stator core 8, insulating members 10 and 11, and a winding 9 formed on the stator core 8.
It consists of and.

The stator core 8 is composed of a plurality of laminated steel plates (metal plates).

As shown in FIG. 10, eight magnetic poles 81 are formed on the inner peripheral side of the stator core 8. Each of the magnetic poles 81 has a plurality of tooth poles 82 arranged in parallel along the circumferential direction. The tooth poles 82 are arranged equidistantly from the center of rotation (axis 151) of the rotor 14, that is, concentrically arranged.

Side surface 8 of the stator core 8 as seen from the axial direction
The shape of 6, that is, the outer shape of the stator core 8 in FIG. 10 is a quadrangle having a chamfered portion 84 at each corner 83. Each chamfered portion 84 is wider than the corresponding chamfered portion 53 of the bracket 5 described later.

In this way, each corner portion 83 of the stator core 8 is
By providing the chamfered portion 84 (by making a part of the stator core 8 cut out), the motor characteristics can be improved without increasing the motor shape (motor size).

Further, at each corner 83 of the stator core 8,
A through hole 85 into which the screw 21 is inserted is formed.

As shown in FIGS. 1 and 2, the stator core 8 has the insulating member 10 inserted from one end side and the insulating member 11 inserted from the other end side. A winding 9 is provided on the stator core 8 through the insulating members 10 and 11. In this way, the insulating member 10
And 11 are interposed, the stator core 8
And the winding 9 can be reliably insulated.

In the state where the rotor 14 is inserted inside the stator 7, the tooth poles 171 and 181 of the rotor cores 17 and 18 are
And the tooth poles 82 of the stator core 8 face each other without contact.
In this case, the tooth poles 171 and 181 of the rotor cores 17 and 18
Between the tooth poles 82 of the stator core 8 and
A gap of about 0.04 to 0.08 mm is formed.

A circuit board 12 is arranged on the lower side of the stator 7 in FIGS. 1 and 2. At the terminal portion of the circuit board 12, both ends of the winding 9 and one end of a lead wire 121 for supplying electric power to the winding 9 are respectively provided.
It is electrically connected. The other end of the lead wire 121 is electrically connected to a drive circuit (drive control circuit) (not shown) of the stepping motor 1.

An insulating sheet 13 for insulating the circuit board 12 and the bracket 5 is provided between the circuit board 12 and the bracket 5.

As shown in FIGS. 3 and 4, the bracket 5 has a substantially square (quadrangular) base 51 and a side wall 52. The side wall 52 is provided on the outer peripheral portion (outer side portion) of the base portion 51 in parallel with the axis 151 and standing toward the stator core 8 side. As will be described later, this side wall 5
2 is a plastic deformation of the metal plate, the main surface 510 of the base 51.
It is bent almost at a right angle to.

This bracket 5 has an end portion 52 of the side wall 52.
1 is attached so as to contact the end surface of the stator core 8. In this case, a predetermined space is formed between the end surface of the stator core 8 and the base 51, and the winding 9 is formed in the space.
Is stored in a state of not contacting the bracket 5. That is, the side wall 52 functions as a spacer for forming a storage space for the winding 9 between the end surface of the stator core 8 and the base 51.

As shown in FIG. 4, the shape of the side surface of the bracket 5 viewed from the axial direction, that is, the side wall 5 in FIG.
The outer shape of 2 is substantially the same as the outer shape of the stator core 8 and is a quadrangle having a chamfered portion 53 at each corner.

As shown in FIG. 3, the chamfered portions 53 of FIG.
A protrusion 523 that increases the height of the side wall 52 is formed on the upper middle side. That is, the protrusions 523 are arranged at the four corners of the bracket 5.

Each protrusion 523 engages with a corresponding chamfered portion 84 (side surface of the stator core 8) of the stator core 8.

The four protrusions 523 constitute engaging portions which engage with the plurality of positions (four chamfered portions 84) on the side surface 86 of the stator core 8.

In this case, due to the engagement of the engaging portions, that is, each of the protrusions 523 has a corresponding chamfered portion 84.
When engaged with, the bearings 3 and 4 and the stator 7 (stator core 8) are aligned so that their centers are the same.
Therefore, each of the protrusions 523 and each of the chamfered portions 84 constitute positioning means for positioning the bracket 5 with respect to the stator 7 (stator core 8).

Since the stepping motor 1 has this positioning means, that is, each protrusion 523 and each chamfered portion 84, it has a high degree of coaxiality (centering accuracy) and can be easily attached to the bearings 3 and 4. , And the center of the stator 7 can be aligned with each other. Therefore, a stepping motor having extremely excellent characteristics can be obtained.

Here, as shown in FIG. 4, the distance between the axis 151 and the protrusion 523 is a, and as shown in FIG.
1 and the position where the protrusion 523 of the side face 86 of the stator core 8 engages, that is, where the distance between the axis 151 and the chamfered portion 84 is b, the relationship of a ≦ b (press fit) is satisfied. It is set.

As shown in FIGS. 4 and 10, the outer surface 522 of the side wall 52 excluding the protrusion 523 and the side surface 86 of the stator core 8 are substantially aligned when viewed in the axial direction. As a result, unnecessary irregularities do not occur on the side surface of the motor, which is advantageous for installation in the device.

As shown in FIGS. 3, 4 and 6, a rectangular notch 524 is formed in the central portion of the side wall 52, through which the wiring for energizing the winding 9, that is, the lead wire 121 is inserted. Has been done.

As shown in FIGS. 3, 4, 5, and 7, a circular opening 511 is formed in the center of the base 51 of the bracket 5. By caulking the bearing 3 on the edge 512 facing the opening 511, the bearing 3
Are fixedly installed on the base 51. Therefore, the opening 5
11 and the edge portion 512 form a bearing support portion that supports the bearing 3.

Further, through-holes (holes for screwing) 515 into which the screws 21 are inserted are formed at the corners (four corners) of the base 51, respectively.

As shown in FIGS. 3, 4 and 5, the base portion 51 of such a bracket 5 has one diagonal line of the base portion 51 (through holes 515, 5 facing each other through the opening 511).
Two straight ribs 56 parallel to the straight line connecting the centers of 15 (hereinafter the same), and two parallel ribs to the other diagonal line of the base 51.
A linear rib 57 of a book is formed. Ie 2
A lattice pattern is formed by the book ribs 56 and the two ribs 57 orthogonal to each other.

The ribs 56 and 57 reinforce the base portion 51 and improve the mechanical strength of the bracket 5.

As a result, the primary natural vibration frequency of the bracket 5 shifts to the high frequency band, so that the amount of vibration of the stepping motor 1 in the frequency band audible to humans is reduced. That is, noise when driving the stepping motor 1 is reduced.

The stress concentrated on the central portion of the bracket 5 when the bracket 5 is fixed with the screws 21 is
The ribs 56 and 57 distribute the ribs 56 and 57 to reduce the amount of displacement (maximum displacement) of the central portion of the bracket 5. As a result, the coaxiality (the degree to which the ideal rotation center of the rotor 14 and the center of the opening 511 coincide with each other) is improved, and thus the motor characteristics can be improved. Also, the yield is improved.

These ribs 56 and 57 are inside the base portion 51 of the bracket 5 (upper side in FIGS. 3 and 5).
Overhangs. Further, as shown in FIGS. 5, 6 and 7, grooves 58 corresponding to the ribs 56 and 57 are formed on the back surface of the base portion 51 (outside the bracket 5). When the ribs 56 and 57 project inside the bracket 5 as described above, there is an advantage that the ribs 56 and 57 do not get in the way even when the brackets 5 are stacked so that their rear surfaces are in contact with each other.

The ribs 56 and 57 are arranged so that the ribs and their extension lines do not intersect the openings 511 and the through holes 515, that is, the ribs pass in the vicinity of the diagonal through holes 515 and the openings 511 parallel to the ribs. Are arranged as follows. The ribs 56 and 57 are respectively
It is arranged at a position equidistant from the center (axis 151) of the opening 511.

Both ends of each rib 56, 57 are connected to the corresponding side wall 52.

The formation pattern of the ribs 56, 57 on the base 51, that is, the grid-like pattern, is defined by the openings 51.
A straight line on the base portion 51 that is point-symmetric with respect to the center of 1 and passes through the center (for example, the diagonal line of the base portion 51, the opening 511
Since it is line-symmetrical with respect to the straight line parallel to the side wall 52 passing through the center of, the balance is good. Therefore, the effects of the present invention described above, that is, the effects of reducing noise and vibration and improving coaxiality are more remarkable.

Here, in the rib 56, a portion between the ribs 57 and 57 is an intermediate portion 561, and portions on both sides of the intermediate portion 561 are end portions 562 and 563, respectively.
When the portions of the ribs 57 between the ribs 56 are the intermediate portions 571 and the portions on both sides of the intermediate portions 571 are the end portions 572 and 573, respectively, the intermediate portions 561 of the ribs 56 and the intermediate portions of the ribs 57. The opening 5 is formed by the portion 571.
A first rib 54 of a quadrangle (square) surrounding 11 is configured. That is, the first rib 54 is made of a linear combination and has four right-angled corners 541.

Further, the respective end portions 562 and 563 of the rib 56 and the respective end portions 572 and 573 of the rib 57 form a second rib 55 which connects the first rib 54 and the side wall 52. It That is, the second rib 55 is
It is a linear combination, and connects each corner 541 and the corresponding side wall 52.

Each through hole 515 is located in a different region defined by the first rib 54 and the second rib 55, respectively. As a result, the effects of reducing noise and vibration and improving coaxiality become more remarkable.

As shown in FIG. 8, the thickness of the base portion 51 is set to h1.
, Where the width of the first ribs 54, 55 is w and the height is h2, the height h2 of the first ribs 54, 55 is
About 10 to 300% of the thickness h1 of the base 51 is preferable,
About 40 to 60% is more preferable.

Height h of first rib 54 and second rib 55
If 2 exceeds 300% of the thickness h1 of the base portion 51, it becomes difficult to manufacture (work) the bracket 5, and if less than 10%,
Depending on various conditions such as the thickness h1 of the base portion 51 and the formation pattern of the first ribs 54 and the second ribs 55, the effects of reducing noise and vibration and improving coaxiality may be insufficient. .

The width w of the first rib 54 and the second rib 55 is preferably about 50 to 300%, more preferably about 130 to 180% of the thickness h1 of the base 51.

When the width w of the first rib 54 and the second rib 55 is set within the above range, the effects of reducing noise and vibration and improving coaxiality become more remarkable.

It is preferable that the surface of the bracket 5 is anticorrosive. Thereby, the chemical durability of the bracket 5 is improved, and the reliability of the stepping motor 1 can be improved. In this embodiment, the anticorrosion plating (zinc plated steel plate) is used as the material, but the bracket 5 may be subjected to anticorrosion treatment such as the same plating after processing.

As shown in FIGS. 1, 2 and 9, the base portion 61 of the bracket 6 is formed with a first rib 54 and a second rib 55. The configurations of the first ribs 54 and the second ribs 55 are the same as the first ribs 54 and the second ribs 55 of the bracket 5 described above, respectively, and therefore description thereof will be omitted.

Further, at each corner portion (four corners) of the base portion 61 of the bracket 6, a screw hole 6 to be screwed with the screw 21 is provided.
3 is formed. The side wall 62 of the bracket 6 has no cutout. The other configuration of the bracket 6 is almost the same as that of the bracket 5 described above, and thus the description thereof is omitted.

In this embodiment, the brackets 5 and 6 are
It is manufactured by using a metal plate such as a steel plate as a material, and subjecting this material to multi-stage continuous press working such as press punching and press bending, and cutting if necessary.

In this case, the first rib 54 and the second rib 55 are preferably formed at the time of molding the brackets 5 and 6, that is, for example, at a predetermined stage of the continuous press working. This makes it possible to form the first ribs 54 and the second ribs 55 on the base 51 without increasing the number of manufacturing steps of the stepping motor 1.

In such a manufacturing method, the shapes as described above, particularly the shapes of the side wall 52, the protrusion 523, the opening 511, the through hole 515, the first rib 54, the second rib 55, etc. can be easily formed. In addition, the brackets 5 and 6 can be formed with high dimensional accuracy, and the mechanical strength of the brackets 5 and 6 is sufficiently high.

The brackets 5 and 6 in the present invention are not limited to those manufactured in this way, but may be manufactured through any of the steps of press working, deep drawing and bending. May be

In the present invention, the brackets 5 and 6 are also included.
One of them may be formed by plastically deforming a metal plate to form a side wall.

In the present invention, the brackets 5 and 6 are also included.
The protrusion (engaging portion) 523 may be provided on only one of the above. Further, the protrusion 523 may be omitted from both the brackets 5 and 6.

In the stepping motor 1 described above, the screw 21 is screwed into the screw hole 63 of the bracket 6 while the stator 7 is sandwiched by the brackets 5 and 6, whereby the stator 7, the bracket 5 and the bracket 6 and 6 are fixed.

Then, when a pulse signal is supplied to the winding 9 through the lead wire 121 and the circuit board 12 by the drive circuit of the stepping motor 1, the winding 9 is excited and a torque for rotationally driving the rotor 14 is generated. . Then, the rotor 14 rotates a predetermined number of steps, that is, a predetermined angle, according to the number of pulses of the input pulse signal.

As described above, in the stepping motor 1, since the first ribs 54 and the second ribs 55 described above are formed on the base portions 51 and 61 of the brackets 5 and 6, respectively, the brackets 5 and 6 are formed. The mechanical strength of 6 is improved, which reduces noise and vibration when the stepping motor 1 is driven.

Then, the stress concentrated on the central portion of the bracket 5 when the stator 7, the bracket 5, and the bracket 6 are fixed by the screw 21 is caused by the first rib 54 and the second rib 55. By the action, the brackets 5 and 6 are dispersed, and the displacement amount of the central portions of the brackets 5 and 6 is reduced, thereby improving the coaxiality.

Further, in the stepping motor 1, the metal plate is plastically deformed mainly by press working, and the side wall 52,
Since the brackets 5 and 6 each having 62 are manufactured and the stator 7 is sandwiched between the brackets 5 and 6, the motor can be manufactured easily and inexpensively. It is also advantageous for small size, light weight and mass production.

For example, as compared with the case where an aluminum die-cast bracket is used, the bracket can be easily manufactured (processed) and the cost can be reduced.

Further, since the stepping motor 1 is a hybrid type stepping motor, it has a higher resolution, that is, a smaller step angle than the PM type stepping motor, which is advantageous when performing precise control. is there.

Next, another embodiment of the stepping motor of the present invention will be described. In this case, description of common points with the stepping motor 1 described above will be omitted, and main differences will be described.

FIG. 11 is a plan view showing the construction of a bracket of another embodiment of the stepping motor of the present invention, FIG.
11 is a rear view of the bracket shown in FIG. 11, FIG. 13 is a plan view showing the configuration of the bracket of another embodiment of the stepping motor of the present invention, FIG. 14 is a rear view of the bracket shown in FIG. 13, and FIG. FIG. 16 is a plan view showing a configuration of a bracket of another embodiment of the stepping motor of the present invention, FIG. 16 is a rear view of the bracket shown in FIG. 15, and FIG. 17 is a bracket of another embodiment of the stepping motor of the present invention. FIG. 18 is a plan view showing the configuration, and FIG. 18 is a rear view of the bracket shown in FIG.

As shown in these figures, each stepping motor 1 includes the above-described stepping motor 1 and the first rib 54 and the second rib 55 formed on the base portions 51 and 61 of the brackets 5 and 6. Only the pattern is different, and other configurations are almost the same.

The base 51 of the bracket 5 shown in FIGS. 11 and 12 is provided with a first rib 54 of a quadrangle (square) surrounding the opening 512. This first rib 54
Are arranged such that one side of the base portion 51 and one side of the first rib 54 are parallel to each other, and the distance from the center of the opening 511 to each side of the first rib 54 is the same.

The first rib 5 is provided on the base 51.
The second ribs 55 extending in the extension direction of the sides of the first ribs 54 are formed from the respective corner portions 541 of No. 4. The ends of the second ribs 55 are connected to the corresponding side walls 62, respectively.

The first rib 54 and the second rib 5
5 forms a grid pattern parallel to one side of the base 51.

The rib pattern formed on the base portion 61 of the bracket 6 is similar to the pattern of the first rib 54 and the second rib 55 formed on the base portion 51 of the bracket 5 shown in FIG. Therefore, illustration and description thereof are omitted.

The base 51 of the bracket 5 shown in FIGS. 13 and 14 has a circular first rib 54 surrounding the opening 512.
Are formed. The first rib 54 has an opening 512.
It is arranged concentrically with.

The first rib 5 is provided on the base 51.
Second ribs 55 extending radially from 4 are formed in four directions. The ends of the second ribs 55 are respectively
It is connected to the corresponding side wall 62. Further, the second ribs 55 are arranged at equal angular intervals (equal intervals).

The pattern of the ribs formed on the base portion 61 of the bracket 6 is the same as the pattern of the first ribs 54 and the second ribs 55 formed on the base portion 51 of the bracket 5 shown in FIG. Therefore, illustration and description thereof are omitted.

Here, in the present invention, the second rib 55 may be appropriately inclined or curved so that the second rib 55 and its extension line do not intersect the opening 511.

The base 51 of the bracket 5 shown in FIGS. 15 and 16 is provided with a quadrilateral (square) first rib 54 surrounding the opening 512. This first rib 54
Is parallel to the diagonal line of the base 51 and one side of the first rib 54, and the first rib 54 extends from the center of the opening 511.
Are arranged so that the distance to each side is the same.

The first rib 5 is provided on the base 51.
Second ribs 55 that connect the respective corner portions 541 of No. 4 and the central portion of the side wall 52 are formed. This second rib 55
Are arranged so as to be parallel to one side of the base portion 51.

Further, the base 51 is formed with four linear ribs 591 that connect the adjacent side walls 52 to each other. Both ends of each rib 591 are respectively provided with the second rib 55.
Connected to or near the end of the. Further, the rib 591 may be omitted.

The pattern of the ribs formed on the base portion 61 of the bracket 6 is the pattern of the first ribs 54, the second ribs 55, and the ribs 591 formed on the base portion 51 of the bracket 5 shown in FIG. Since it is the same as, the illustration and description will be omitted.

The base portion 51 of the bracket 5 shown in FIGS. 17 and 18 has a first rib 54 and a second rib having the same pattern as that of the first rib 54 and the second rib 55 shown in FIG. 55 is formed.

In addition to this, a rib 592 which is concentric and similar to the first rib 54 is formed on the base portion 51. Each corner 593 of the rib 592 is connected to the center of the side wall 52. This rib 592 is
It also serves as the rib and the second rib.

The pattern of the ribs formed on the base portion 61 of the bracket 6 is the pattern of the first ribs 54, the second ribs 55, and the ribs 592 formed on the base portion 51 of the bracket 5 shown in FIG. Since it is the same as, the illustration and description will be omitted.

Also in the stepping motor 1 shown in FIGS. 11 to 18, the first ribs 5 are provided on the base portions 51 and 61 as in the stepping motor 1 shown in FIGS.
4, the provision of the second rib 55 and the like improves the mechanical strength of the bracket 5, which reduces noise and vibration when the stepping motor 1 is driven, and the screw 21.
Thus, the amount of displacement of the central portions of the brackets 5, 6 when the stator 7, the bracket 5, and the bracket 6 are fixed is reduced, which improves the coaxiality.

The use of the stepping motor of the present invention is not particularly limited.
It can be used for paper feeding of printers, facsimiles, scanners, copiers, etc.

[0117]

EXAMPLES Next, specific examples of the stepping motor of the present invention will be described.

Example 1 A stepping motor shown in FIGS. 1 to 10 was manufactured. The patterns of the ribs of the pair of brackets in the stepping motor according to the first embodiment are the same and are as shown in FIGS. 4 and 9, respectively. The various conditions for this stepping motor are as follows.

Outer diameter of rotor: 25 mm Bracket material: SPCE Bracket dimensions: 42 mm length × 42 mm width × 8 mm height Bracket base thickness h1: 1.2 mm Rib height h2: 0.6 mm (of h1 50%) Width w of rib: 2.0 mm (167% of h1) (Example 2) Stepping motor similar to Example 1 except that both brackets were changed to the rib patterns shown in FIGS. 11 and 12. Was manufactured.

(Example 3) A stepping motor similar to that of Example 1 was manufactured except that both brackets were changed to the rib patterns shown in Figs. 13 and 14.

Example 4 A stepping motor similar to that of Example 1 was manufactured except that both brackets were changed to the rib patterns shown in FIGS. 15 and 16.

(Embodiment 5) A stepping motor similar to that of Embodiment 1 was manufactured except that both brackets were changed to the rib patterns shown in FIGS. 17 and 18.

(Comparative Example) Both brackets have the rib pattern shown in FIGS. 19 and 20, that is, the opening 511.
A stepping motor similar to that of Example 1 was manufactured, except that a rib in which the rib 540 and the side wall 52 were not connected was changed to a bracket. The various conditions for this stepping motor are as follows.

Outer Diameter of Rotor: Same Bracket Material as in Example 1: Same Bracket Dimension as in Example 1: Same Bracket Base Thickness h 1 as in Example 1: Same Rib 540, 550 Height as in Example 1 H2: Width w of the same rib 540 as in the first embodiment: Width w of the same rib 550 as in the first embodiment: 2.0 to 5.0 mm (167 to h1)
417%) Next, for each of the stepping motors of Examples 1 to 5 and Comparative Example, the maximum displacement of the bracket when assembled by tightening with four screws under the following conditions, and the primary natural vibration frequency of the bracket Then, the amount of vibration in the finished motor product and the noise in the finished motor product were obtained. The results are shown in FIGS.

<Maximum displacement of bracket when tightening screws>
Both brackets were fixed with four screws so that a tightening torque of 100 kgf per screw was applied, the displacement amount of each part of the base of the bracket was measured, and the maximum value (maximum displacement amount) was obtained.

In the brackets of the stepping motors of Examples 1 to 5, the maximum value was shown in the vicinity of the screw at the base of the bracket, whereas in the bracket of the stepping motor of the comparative example, the central part of the base of the bracket was used. Shows the maximum value.

<Primary Natural Vibration Frequency of Bracket> The primary natural vibration frequency of one of the brackets was measured by itself. The measuring method is as follows.

As shown in FIG. 25, the acceleration pickup 224 connected to one input terminal of the amplifier 223 was attached to the base of the bracket, and the bracket was suspended by the thread 221. Then, the blacket is hit once with the impulse hammer 222 connected to the other input terminal of the amplifier 223, the output from the amplifier 223 at this time is analyzed by the FFT analyzer 225, and the frequency at which the vibration amount becomes maximum (primary The natural vibration frequency) was obtained.

<Vibration Amount in Complete Motor Product> A stepping motor was rotationally driven to measure a vibration amount (frequency characteristic of the vibration amount), and a total value of the vibration amounts of 20 to 16000 Hz was obtained. The driving conditions for the stepping motor were two-phase excitation, 4000 pps, and voltage 35V.

<Noise in finished motor> As shown in FIG. 26, in a soundproof room, on a stand 227 having a height of 75 cm,
The stepping motor 1 is arranged so that the output shaft of the motor faces the back side of the paper in FIG. Also, the microphone 22
6 from the stepping motor 1 to the left side in FIG.
It was installed at a position of 150 cm from the floor 228 to the upper side in FIG. 26 (position of stepping motor 1 to 125 cm).

Then, the stepping motor 1 was rotationally driven to measure the noise. The driving conditions for the stepping motor were two-phase excitation, 4000 pps, and voltage 35V.

<Consideration of Results> As shown in the graph of FIG. 1, in the stepping motors of Examples 1 to 5, the ribs improve the mechanical strength of the brackets and are concentrated in the central portion of the brackets. It can be seen that the stress is dispersed by the action of the ribs, and therefore the maximum displacement of the bracket during screw tightening is small. As described above, the maximum displacement amount of the bracket of the stepping motor according to the first to fifth embodiments is a value in the vicinity of the screw of the bracket, so that the displacement amount of the central portion of the bracket is smaller. The coaxiality is high. Of these examples, Example 1,
In Nos. 2 and 3, particularly, the maximum displacement amount is small and the coaxiality is high.

On the other hand, in the stepping motor of the comparative example, the maximum displacement amount of the bracket when tightening the screw is large,
As described above, this maximum displacement amount is the value at the central portion of the bracket, so the coaxiality is low.

In each of the stepping motors of Examples 1 to 5, as shown in the graph of FIG. 2, the primary natural vibration frequency of the bracket 5 is high, and as shown in the graph of FIG. It is understood that the amount of vibration (total value) in the frequency band audible to human beings is small, and the noise in the completed motor product is small, as shown in the graph of FIG. Of these examples, the examples 1 and 3 have particularly low noise.

On the other hand, in the stepping motor of the comparative example, as shown in the graph of FIG. 2, the primary natural vibration frequency of the bracket 5 is low, and as shown in the graph of FIG. The vibration amount (total value) in the frequency band is large, and as shown in the graph of FIG. 4, the noise in the completed motor product is large.

The stepping motor of the present invention has been described above based on the illustrated embodiments. However, the present invention is not limited to these, and in particular, each constituent element of the stepping motor has the same structure. It can be appropriately replaced with any that can generate a function.

For example, in each of the illustrated embodiments, the first rib and the second rib protrude inside the bracket, but in the present invention, the first rib and the second rib protrude outside the bracket. May be.

Further, in the present invention, the first rib and the second rib
The rib may be formed on only one of the brackets.

Further, in the present invention, the first rib and the second rib
The conditions such as the dimensions of the ribs, the patterns of the first ribs and the second ribs, and the like are not limited to the illustrated embodiments.

In each of the illustrated embodiments, the hybrid type stepping motor has been described, but the present invention is not limited to this and may be a VR type or PM type stepping motor.

However, among these modes, a hybrid type or VR type stepping motor is preferable.

[0142]

As described above, according to the stepping motor of the present invention, by providing the above-mentioned first and second ribs on the base portion of the bracket, it is possible to increase the thickness of the base portion (workability). , The mechanical strength of the bracket can be improved without impairing productivity.

As a result, the primary natural vibration frequency of the bracket shifts to the high frequency band, so that the amount of vibration of the stepping motor in the frequency band audible to humans is reduced. That is, noise when driving the stepping motor is reduced.

In the present invention, the stress concentrated in the central portion of the bracket when the bracket is fixed with screws is dispersed by the action of the first and second ribs, and the central portion of the bracket is dispersed. The amount of displacement decreases. As a result, the coaxiality is improved, and thus the motor characteristics can be improved. Also, the yield is improved.

Further, when the first rib has a corner portion, particularly when the formation pattern on the base portions of the first and second ribs is a lattice shape, noise is further reduced and coaxiality is further improved. improves.

Further, when the first rib and its extension line are constructed so as not to intersect with the opening and / or hole formed in the base, or the second rib and its extension line are provided with the opening and / or hole. If it is configured so as not to intersect with the hole, the noise is reduced and the coaxiality is further improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a stepping motor of the present invention.

FIG. 2 is a sectional view of the stepping motor shown in FIG.

3 is a perspective view showing a configuration of a bracket of the stepping motor shown in FIG. 1. FIG.

FIG. 4 is a plan view of the bracket shown in FIG.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is a front view of the bracket shown in FIG.

FIG. 7 is a rear view of the bracket shown in FIG.

8 is a cross-sectional view showing a first rib of the bracket shown in FIG. 3 and its vicinity.

9 is a perspective view showing a configuration of a bracket of the stepping motor shown in FIG. 1. FIG.

10 is a plan view showing a configuration of a stator core of the stepping motor shown in FIG.

FIG. 11 is a plan view showing a configuration of a bracket of another embodiment of the stepping motor of the present invention.

FIG. 12 is a rear view of the bracket shown in FIG.

FIG. 13 is a plan view showing the configuration of a bracket of another embodiment of the stepping motor of the present invention.

FIG. 14 is a rear view of the bracket shown in FIG.

FIG. 15 is a plan view showing a configuration of a bracket of another embodiment of the stepping motor of the present invention.

16 is a rear view of the bracket shown in FIG.

FIG. 17 is a plan view showing the configuration of a bracket of another embodiment of the stepping motor of the present invention.

18 is a rear view of the bracket shown in FIG.

FIG. 19 is a plan view showing a bracket of a stepping motor of a comparative example.

20 is a rear view of the bracket shown in FIG.

FIG. 21 is a graph showing the maximum displacement of the bracket when tightening the screws.

FIG. 22 is a graph showing a primary natural vibration frequency of a bracket.

FIG. 23 is a graph showing a vibration amount (total value) in a completed motor product.

FIG. 24 is a graph showing noise in a completed motor product.

FIG. 25 is a diagram showing a method for measuring a primary natural vibration frequency of a bracket.

FIG. 26 is a diagram showing a method of measuring noise in a completed motor product.

[Explanation of symbols]

1 stepping motor 2 pulley 3, 4 bearing 5 First bracket (bracket) 51 base 510 main surface 511 opening 512 edge 515 through hole 52 Side wall 521 Edge 522 exterior 523 protrusion 524 Notch 53 Chamfer 54 First Rib 541 Corner 55 Second Rib 56 ribs 561 middle part 562, 563 edge 57 ribs 571 middle part 572, 573 Edge 58 groove 591 and 592 ribs 593 Corner 6 Second bracket (bracket) 61 base 62 Side wall 63 screw holes 7 Stator 8 Stator core 81 magnetic pole 82 Tooth pole 83 corners 84 Chamfer 85 through hole 86 side 9 windings 10, 11 Insulation member 12 circuit board 121 lead wire 13 Insulation sheet 14 rotor 15 rotation axis 151 axis 16 permanent magnet 17, 18 rotor core 171, 181 tooth pole 19 washers 21 screws 221 thread 222 impulse hammer 223 amplifier 224 Accelerometer 225 FFT Analyzer 226 microphone 227 units 228 floor 540 and 550 ribs

Continuation of the front page (56) Reference JP-A-6-189488 (JP, A) JP-A-51-108215 (JP, A) JP-A-7-75281 (JP, A) JP-A-5-276708 (JP , A) Actual development Sho-255-251 (JP, U) Actual development 3-11349 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 37/00 H02K 5/00

Claims (15)

(57) [Claims] 1. A quadrangular stator having chamfers at each corner, and a quadrangular stator having chamfers at each corner, having an opening formed at the center and a plurality of screw holes at the outer periphery. A pair of brackets each having a base portion formed with a base portion and side walls provided upright with respect to the base portion, and attached to both ends of the stator; and fixed in respective openings of the base portions of the brackets. A stepping motor having a pair of bearings and a rotor inserted inside the stator and rotatably supported by the bearings, wherein at least one of the brackets has a base portion and an outer peripheral portion. An annular first rib formed along the first rib is connected to the first rib so as to connect the respective side walls of the quadrangular shape, and the first rib passes near the opening and faces each other. Stepping motor and having a second rib that is formed linearly in parallel. 2. A quadrangular stator having chamfers at each corner, and a quadrangular stator having chamfers at each corner, having an opening formed in the center and a plurality of holes for screwing in the outer periphery. A pair of brackets each having a base portion formed with a base portion and side walls provided upright with respect to the base portion, and attached to both ends of the stator; and fixed in respective openings of the base portions of the brackets. A stepping motor having a pair of bearings and a rotor inserted inside the stator and rotatably supported by the both bearings, wherein the both brackets are formed along the outer periphery at the base thereof. Connected to the first rib so as to tie the annular first rib and the respective side walls forming the quadrangle,
A stepping motor having a second rib formed in a straight line so as to pass in the vicinity of the opening and parallel to each other. 3. The stepping motor according to claim 1, wherein at least one of the both brackets is formed by plastically deforming a metal plate. 4. The stepping motor according to claim 3, wherein the bracket is manufactured through a press working process, a deep drawing process or a bending process. 5. The first rib and the second rib are formed at the time of molding the bracket.
Alternatively, the stepping motor according to item 4. 6. The stepping motor according to claim 1, wherein the first rib has a corner portion. 7. The stepping motor according to claim 1, wherein the first rib is a linear combination. 8. The stepping according to claim 1, wherein the first rib is configured such that the first rib and its extension line do not intersect with the opening and / or the hole. motor. 9. The stepping according to claim 1, wherein the second rib is configured so that the second rib and its extension line do not intersect with the opening and / or the hole. motor. 10. The stepping motor according to claim 1, wherein the second rib is connected to a plurality of portions of the side wall. 11. The stepping motor according to claim 1, wherein the hole is located in two or more different areas defined by the first rib and the second rib. 12. The hole portion is formed at each of four corners of the base portion, and each hole portion is located in a different region defined by the first rib and the second rib, respectively. 1. The stepping motor according to 1. 13. The stepping motor according to claim 1, wherein the first ribs and the second ribs have a lattice shape. 14. The stepping motor according to claim 1, wherein the grid in the formation pattern is parallel to one side of the base portion or parallel to a diagonal line of the base portion. 15. The formation pattern of the first rib and the second rib on the base is point-symmetric with respect to the center of the opening, or is a line with respect to a straight line on the base passing through the center. The stepping motor according to claim 1, which is symmetrical.