JP3269395B2 - 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 stepping motor suitable for use as a drive source for precisely driving a pointer such as a speedometer.

[0002]

2. Description of the Related Art At present, a stepping motor is used for a very wide range of applications, and is particularly remarkably applied to a rotating system requiring fine movement. FIG. 7 is a diagram illustrating an example of such a stepping motor, and is an exploded perspective view illustrating a configuration example of a stepping motor used for a speedometer or the like.

In FIG. 7, reference numerals 31 _-1 and 31 _-2 denote flat cylindrical bobbins, and a coil 32 is wound around the outer periphery thereof. Each of the bobbins 31 _-1 and 31 _-2 has a magnetic yoke 31a over both end surfaces and a central hollow portion.
Are formed.

The bobbin _31-1 and the bobbin _31-2 are overlapped with each other, and a cylindrical magnet 33 penetrates the hollow portion. A shaft 34 is provided at the center of the axis of the magnet 33.
Are attached to form a rotor.

Further, the bobbins 31 _-1 and 31 _-2 and the magnet 33 are superimposed on a plate 35 having a through bearing 35a at the center, and are covered from the bobbin _31-1 side by a cup 36 formed of a magnetic material. .

The cup 36 is formed in a cylindrical shape whose one end is closed by a plate portion 36b having a through bearing 36a at the center. Thus, the aforementioned shaft 34
Each end side is a through bearing 35a or a through bearing 36
The shaft 34 outputs a rotational driving force.

[0007]

By the way, the stepping motor is used as an actuator of various control devices, and is particularly applied to a rotary drive system device. Therefore, the stepping motor is not only inexpensive but also has an intermittent performance. There is a need for quick response during driving, accuracy of the stationary angle, and the like.

The above-described bobbins 31 _-1 and 31 _-2 each have pole teeth on the inner surface of the central cavity. In the stepping motor shown in FIG. 7, it is necessary and pole teeth having the pole teeth and the bobbin 31 _-2 with bobbin 31 _-1 during assembly are mutually have displacement in the predetermined angle.

However, according to the configuration shown in FIG.
Bobbin 31 during assembly_-1And bobbin 31 _-2Magnetic balance with
And the step angle error of the shaft 34
Was easy to occur.

Further, since the cup 36 is formed by pressing, the manufacturing cost is increased, and the cup 36 tends to be tapered at the time of forming. Therefore, the adhesion between the inner surface of the cylindrical portion and the yokes 31a, 31a is poor, and the generated torque and the step angle accuracy cannot be increased.

Further, one yoke 31a and the other yoke 31a
31a is a connecting portion 41 on the inner surface of the inner cylindrical portion of the cup 36.
Magnetically connected to the coil 32 to excite the coil 32
Depending on the pattern, one bobbin 31_-1Formed on the side
Magnetic circuit and other bobbin 31 _-2Magnetic circuit formed on the side
However, when the cup 36 conducts and magnetic interference occurs.
There was a thing.

Namely, as shown in FIG. 8 (a), the pole teeth 42a of one of the bobbins 31 _-1 side, the other bobbin 31 _-2
If the pole teeth 42b on the side have the same magnetic pole, they repel each other, so that no magnetic interference occurs between the bobbins 31 _-1 and 31 _-2 , but the excitation pattern changes to change the pole teeth. When the magnetic poles 42a and 42b have different magnetic poles, as shown in FIG.
2a, a magnetic field is generated in the direction of the pole teeth 42b.
1 _-1, magnetic interference occurs between 31 _-2.

As described above, there is a case where magnetic interference occurs and a case where magnetic interference does not occur due to a change in the excitation pattern, which causes a problem that rotation unevenness occurs. In particular, when used for a motor for driving a pointer such as a speedometer, there is a problem that the movement of the pointer is not smooth.

The present invention has been made under such a background, and an object of the present invention is to provide a stepping motor which can increase the generated torque and the step angle accuracy, reduce the rotation unevenness, and reduce the manufacturing cost. .

[0015]

According to a first aspect of the present invention, there is provided a rotor comprising a cylindrical magnet and a shaft mounted on a shaft of the cylindrical magnet. , A first yoke, a second yoke and first and second coils wound therearound, respectively, and a bobbin covering the rotor, and a first and a second yoke covering the bobbin. And a cylindrical magnetic body having elasticity that presses from outside in the radial direction.

According to the present invention, the cylindrical magnetic body having elasticity presses the first and second yokes from the outside in the radial direction. A circuit can be formed.

According to a second aspect of the present invention, in the stepping motor according to the first aspect, the magnetic body covers the outer peripheral surface of the first yoke;
The second yoke and the second magnetic body covering the outer peripheral surface are divided at an interval from each other.

According to the present invention, the magnetic body covering the outer peripheral surface of the yoke comprises: the first magnetic body covering the outer peripheral surface of the first yoke;
The second yoke is divided into a second magnetic body that covers the outer peripheral surface of the second yoke, and these magnetic bodies are arranged at an interval. Therefore, one bobbin and the other bobbin are magnetically connected to each other. And the magnetic interference between both bobbins can be suppressed.

According to a third aspect of the present invention, in the stepping motor according to the first or second aspect, the first yoke and the second yoke are formed of a non-magnetic material (1).
c) are formed integrally with the bobbin with the first pole tooth row (11a _-1 , 11a _-2.
-) and the second pole tooth arrays included in the second yoke (11b _-
1 , 11b _-2 ...) Are characterized by being arranged with a predetermined angular shift in the circumferential direction.

According to the present invention, since the first yoke and the second yoke are formed integrally with the bobbin with the non-magnetic material interposed therebetween, the axes of these yokes are displaced when assembling the stepping motor. Without the first yoke of the first yoke
And the second pole tooth row of the second yoke are securely arranged at predetermined angular deviations in the circumferential direction.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Note that the stepping motor described in this embodiment will be described as an example in which the stepping motor is used for an application such as a speedometer.

FIG. 1 is an exploded perspective view showing the configuration of a stepping motor according to an embodiment of the present invention. FIG. 2 is a sectional view showing an AA ′ section and a BB ′ section in FIG.

FIG. 3 is a perspective view showing the external structure of the stepping motor shown in FIG. 1 or 2 after assembly is completed.

1 and 2, reference numeral 1 denotes a cylindrical bobbin. The bobbin 1 includes a yoke 1a _-1 and the pole teeth 11a of the annular magnetic body pole teeth 11a _-1 · · · protrudes perpendicularly _-2
· Yoke 1a _-2 annular magnetic body projecting perpendicularly, and the pole teeth 11b _-1 · · · is the yoke 1b _-1 and the pole teeth 11b _-2 · · · annular magnetic body projecting perpendicularly A vertically protruding annular magnetic yoke 1b- ₂ is laminated with a nonmagnetic spacer 1c interposed therebetween.

The above-mentioned yokes 1a- ₁ , 1a- ₂ , 1b- ₁ and 1b- ₂ have the same diameter and are formed coaxially.
A coil 2a is wound between the yokes 1a- ₁ and 1a- _2, and a coil 2 is wound between the yokes 1b- ₁ and 1b _- 2.
b is wound.

The pole teeth 11a- ₁ ... And the pole teeth 11a- _2.
.. or pole teeth 11b- ₁ ... and pole teeth 11b- ₂ ...
Project from each other and each yoke 1a _-1 , 1
a- ₂ , 1b- ₁ and 1b- ₂ are arranged so as to be shifted by a predetermined angle α with respect to the circumferential direction. Is determined by a magnetizing angle interval of the magnet 3 described later.

The pole teeth 11a _-1 ... And the pole teeth 11b _-1.
.. or pole teeth 11a- ₂ ... and pole teeth 11b- ₂ ...
Are also shifted by a predetermined angle β with respect to the circumferential direction of each of the yokes 1a- ₁ , 1a- ₂ , 1b- ₁ and 1b- ₂ . A through bearing 1f is formed at the center of the bottom 1e (see FIG. 2) of the bobbin 1.

The above-mentioned magnet 3 has a cylindrical shape and is magnetized at predetermined angular intervals in the circumferential direction (not shown). Reference numeral 4 denotes a shaft for extracting the rotational force of the magnet 3, which is attached to the center of the magnet 3 and forms a rotor.

Reference numeral 5 denotes a cover having a flange 5a, and has a through bearing 5b at the center.

Reference numeral 6 denotes a wound spring wound around the bobbin 1 except for the terminal 1d. The winding spring 6 is made of a cylindrical magnetic material having elasticity such that the yokes 1a- ₁ , 1a- ₂ , 1b- ₁ and 1b- ₂ are pressed from the outside in the radial direction.
The yokes 1a _-1 , 1a _-2 , 1b _-1 and 1b _-2 are formed into a cylindrical shape smaller than the outer diameter.

In the stepping motor shown in FIGS. 1 and 2, one end (lower end in the figure) 4a of the shaft 4 is penetrated through the through bearing 1f and rotatably supported to assemble the magnet 3 in the central cavity of the bobbin 1 during assembly. Incorporate in.

The other end of the shaft 4 (the upper end in the figure)
4b, penetrating through bearing 5b and rotatably supported,
The open surface of the cavity of the bobbin 1 is closed by the cover 5. Then, the outer peripheral portion of each of the yokes 1a _-1 , 1a _-2 , 1b _-1 and 1b _-2 is covered with a winding spring 6.

7 (see FIG. 2) is a cavity formed by the pole teeth 11a _-1 , 11a _-2 , 11b _-1 , 11b _-2 ... In the center of the bobbin 1. When the rotor (magnet 3 and shaft 4) is installed inside
This is a leaf spring that eliminates backlash generated in the axial direction of the shaft 4. By the leaf spring 7, the magnet 3 is connected to the bobbin 1.
The play is eliminated by being urged toward the bottom 1e side of the tire, thereby eliminating play.

The winding spring 6 of the present embodiment comprises a magnetic material having elasticity, which is composed of yokes 1a- ₁ , 1a- ₂ , 1b- ₁ and 1b.
_-2 , so that they are pressed from the outside in the radial direction.
a- ₁ , 1a _-2 , 1b _-1, and 1b _-2 are formed into a cylindrical shape smaller than the outer diameter, and the respective yokes 1a _-1 , 1a _-2 , 1
It easily adheres to the outer periphery of b- ₁ or 1b- ₂ .

For this reason, the winding spring 6 and each of the yokes 1a _-1 , 1
The magnetic circuit is strongly formed by a- ₂ , 1b- ₁ and 1b- ₂ . Therefore, the generated torque and the step angle accuracy can be improved.

Each yoke 1a_-1, 1a_-2, 1b_-1You
And 1b_-2Is formed integrally with the bobbin 1 and
At the time of assembly_-1..., 11a_-2... 1
1b _-1... and 11b_-2... are predetermined for each other
Are arranged with an angle deviation of. Therefore, the shaft 4
Angle error is reduced.

FIG. 4 shows that the coil spring 6 is connected to the first yoke 1.
a_-1, 1a_-2First spring 6 covering the outer peripheral surface of_-1And the second
Yoke 1b_-1, 1b_-2Second spring 6 covering the outer peripheral surface of the spring
_-2It is divided into These springs 6_-1, 6
_-2Is the yoke 1a_-1, 1a_-2Outer peripheral surface and yoke 1b
_-1, 1b_-2Cover each other at an interval
Each forms an independent magnetic path.

That is, the excitation pattern changes and the pole teeth 11a _{- 2} on the yoke 1a- ₂ side and the pole teeth 11 on the yoke 1b- ₁ side.
Even if b _-1 has different magnetic poles, these yoke 1
Since a _-1 and 1a _-2 and yoke 1b _-1 and 1b _-2 are not magnetically connected, no magnetic interference occurs. Therefore, it is possible to avoid the occurrence of rotational unevenness due to magnetic interference due to a change in the excitation pattern.

FIG. 6 is a perspective view showing the appearance of a stepping motor according to an application example of the embodiment when the winding spring 6 is used. The present invention has a terminal 1d- ₁ for supplying an exciting current to the coil 2a and a terminal 1d- ₂ for supplying an exciting current to the coil 2b, as shown in FIG.
The terminal pins may be configured to protrude in the shaft end direction. FIG. 6 is also the same when the coil springs 6 _-1 and 6 _-2 are used.

Further, in addition to the structure having the terminal 1d at the center in the axial direction as shown in FIG. 3, the terminal 1d is provided at one of the shaft ends as shown in FIG. It may be configured to protrude toward the shaft end.

For example, by configuring the terminals as shown in FIGS. 6A and 6B, the stepping motor can be directly mounted on a printed circuit board or the like. That is, wiring becomes unnecessary, and the number of fixed parts and the number of man-hours are reduced, so that the stepping motor can be easily incorporated.

Although the stepping motor described in the present embodiment has been described as an example used for applications such as a speedometer, the present invention is also applicable to a stepping motor used for a printer or a sensor. Applicable.

[0043]

As is clear from the above description, according to the present invention, the following effects can be obtained. (A) In the stepping motor according to the first aspect,
The cylindrical magnetic body having elasticity that covers the first and second yokes and compresses the first and second yokes from the outside in the radial direction easily adheres to the first and second yokes and has a strong magnetic circuit. Is formed, the generated torque and the step angle accuracy can be increased, and the manufacturing cost can be reduced.

(B) In the stepping motor according to the second aspect, the magnetic material covering the outer peripheral surface of the yoke is composed of the first magnetic material covering the outer peripheral surface of the first yoke and the outer peripheral surface of the second yoke. It is divided into a second magnetic body to be covered, and these magnetic bodies are arranged at an interval from each other, so that one bobbin and the other bobbin are not magnetically connected, and Magnetic interference between them can be suppressed, and rotation unevenness can be reduced.

(C) In the stepping motor according to the third aspect, the first yoke has the first yoke since the first yoke and the second yoke are formed integrally with the bobbin with the nonmagnetic material interposed therebetween. The first pole tooth row and the second pole tooth row of the second yoke are securely arranged at predetermined angular deviations in the circumferential direction, and when the stepping motor is assembled, the axes of these yokes are aligned with each other. The magnetic balance can be maintained without deviation, and the occurrence of a step angle error can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing an AA ′ section and a BB ′ section in FIG. 1;

FIG. 3 is a perspective view showing an external configuration of the stepping motor shown in FIG. 1 or 2 after assembly is completed.

FIG. 4 is an exploded perspective view of a stepping motor according to another embodiment of the present invention.

FIG. 5 is a sectional view showing an AA ′ section and a BB ′ section in FIG. 4;

FIG. 6 is a perspective view showing the appearance of a stepping motor according to an application of the present embodiment.

FIG. 7 is an exploded perspective view showing a configuration example of a conventional stepping motor.

FIG. 8 is an enlarged development view of pole teeth of the stepping motor.

[Explanation of symbols]

1 bobbin 1a- ₁ , 1a- ₂ yoke (first yoke) 1b- ₁ , 1b- ₂ yoke (second yoke) 1c spacer (non-magnetic material) 2a, 2b Coil (first, second coil) 3 Magnet (cylindrical magnet) 4 Shaft 6 Winding spring (cylindrical magnetic body) _6-1 Winding spring (first magnetic body) _6-2 Winding spring (second magnetic body) 11a _-1 , 11a _-2 ... Pole teeth (first pole tooth row) 11b _-1 , 11b _-2 ... pole teeth (second pole tooth row)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02K 37/00-37/24 H02K 1/00-1/16 H02K 1/18-1/26 H02K 1 / 28-1/34 H02K 21/00-21/48

Claims (3)

(57) [Claims] 1. A rotor comprising a cylindrical magnet (3) and a shaft (4) mounted on the axis of the cylindrical magnet, a first yoke (1a- ₁ , 1a- ₂ ) and a second yoke. A bobbin (1) having yokes (1b- ₁ and 1b- ₂ ) and first and second coils (2a and 2b) wound therearound, and covering the rotor, and covering the bobbin, A stepped motor, comprising: a cylindrical magnetic body (6) having elasticity for compressing the first and second yokes from the outside in the radial direction. Wherein said cylindrical magnetic body, the first of the first magnetic body covering an outer peripheral surface of the yoke (6 _-1), a second magnetic body covering an outer peripheral surface of the second yoke ( _6-2) in the stepping motor according to claim 1, characterized by being divided at a mutual distance. 3. The first yoke and the second yoke are formed integrally with the bobbin with a non-magnetic material (1c) interposed therebetween, and a first pole tooth row ( 11a
_-1 , 11a _-2 ...) And the second pole tooth row (11b _-1 , 11b _-2 ...) Of the second yoke are arranged at predetermined angular deviations in the circumferential direction. 3. The stepping motor according to claim 1, wherein