JP2000166186A - Compact motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably prevent noise by forming an inclined shape where the front end part of a first resistance part is brought into contact with a commutator before wearing a brush contact surface for wearing due to the progress of brush wearing and hence gradually reaching the contact of an entire surface. SOLUTION: A brush 10 is an inclined double-layer brush, and is provided with a first resistance part 101 that is formed gradually narrower towered the rear side from the front side in the rotary direction of a commutator 3 and a second resistance part 102 that is formed gradually wider toward the rear side. Then, when the brush 10 is rotated, the contact surface of the brush 10, a tip corner 1 of the first resistance part 101 is brought into contact with a first segment of the commutator at the initial stage for the contact surface of the brush 10, and a triangular slide surface that is gradually thinned toward the rear is slid to a rear end corner 2. Further, wearing of the brush 10 proceeds and the tip corners 1 and 3 touch the commutator, thus spreading a slide zone to the second resistance part 102. After that, wearing proceeds further, thus resulting in entire surface sliding and hence reducing vibration and electromagnetic noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush structure of a small motor, and more particularly to a small motor that reduces magnetic noise caused by a short-circuit current between the brush and a commutator.

[0002]

2. Description of the Related Art Since a motor of a blower of an air conditioner for a vehicle is installed in a vehicle cabin, there is a problem in that metallic noise of 1 to 5 kHz is generated. The cause is that vibration of the motor causes resonance of the case. In particular, in a motor provided with a brush, a sharp current change occurs at the time of so-called commutation for switching the magnetic field. At this time, vibration of the motor occurs, which causes resonance of the motor case.

As a countermeasure against the above problem, Japanese Patent Laid-Open No.
According to No. 70511, there is proposed an oblique two-layer brush in which the contact resistance of the brush is devised. This brush is formed so that the resistance gradually increases from the front side to the downstream rear side in the rotation direction of the rotor, suppressing the short-circuit current generated in the armature coil and suppressing the generation of sparks caused by the reactance voltage. it can.

[0004]

However, in the prior art, the effect cannot be improved unless the rotating surface of the commutator and the contact surface of the brush are completely matched. There has been a problem that the contact state cannot be achieved as intended.

The present invention solves such a problem, and provides a small-sized motor that suppresses a sudden current change due to a short-circuit current and reliably prevents noise even when processing is uneven due to a shape change. The purpose is to:

[0006]

In order to achieve the above object, according to the present invention, there is provided a small motor having a stator and a rotor, wherein the stator is provided with a brush having a substantially rectangular parallelepiped shape, The brush has a first resistance portion formed such that a cross section viewed from the commutator side of the rotor is gradually narrowed from a front side to a rear side in a rotor rotation direction, and a cross section viewed from the commutator side of the rotor has a rotor rotation direction. It is formed so that it gradually becomes wider from the front side of the direction to the rear side,
And a second resistance portion having a larger resistance value than the first resistance portion, and a contact surface of the brush with a commutator has at least a front end in a rotor rotation direction of the first resistance portion before brush wear. First, the brush is brought into contact with the commutator, and is unevenly worn due to the progress of the brush wear to gradually come into contact with the entire surface, and has an inclined shape in which the resistance value is gradually increased toward each commutation end.

According to a second aspect of the present invention, in the small-sized motor according to the first aspect, the wear contact surface has a substantially triangular shape.

According to a third aspect of the present invention, in the small motor according to the first or second aspect, before the brush is worn, an end of the first resistance portion other than a front end in the rotor rotation direction is connected to the first resistance portion. The contact height is the same as the front end of the one resistance part in the rotor rotation direction.

[0009]

According to the above structure, the small motor according to the present invention has:
The next contacting adjacent commutator strip is that the current contacting commutator strip sharply reduces its area percentage,
This will rapidly increase the contact area. In addition, even if the commutator is assembled with a slight inclination due to dimensional variations, the low-resistance part is likely to come into contact first, and at the beginning of rectification, a potential difference occurs that cancels the short-circuit current between the shorted commutators. I do. Therefore, since there is almost no sudden current change caused by the short-circuit current, it is effective even when the generation of the spark caused by the reactance voltage as in the past is assembled at an initial stage and inclined due to the dimensional error. Can be suppressed.

Further, according to the second aspect, since the wear contact surface has a triangular shape, the shape is easy and the cost for manufacturing the brush can be suppressed. Further, according to the third aspect, the other end portion is mostly a high resistance portion and is several tens of times the low resistance portion, so that it is hardly affected even if it comes into contact with the other end portion. Sliding is more stable than single-point support at the end, and vibration and the like can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention shown in the drawings will be described. FIG. 1 is a sectional view of a small motor showing a first embodiment of the present invention. In FIG. 1, 1 is an armature,
Reference numeral 2 denotes a rotating shaft, and reference numeral 3 denotes a commutator fixed to the rotating shaft 2.
Reference numeral 4 denotes a yoke housing, and reference numeral 5 denotes a magnet fixed to the inner wall of the yoke housing 4. Reference numeral 6 denotes an end frame serving as a cover of the yoke housing, and reference numeral 10 denotes a brush. The rotating part including the armature 1 is called a rotor, and the non-rotating part supporting the rotating part is called a stator.

FIG. 2 is an explanatory view of a brush device housed inside the small motor of FIG. 1 and fixed to the end frame 6. Reference numeral 7 denotes a brush holder, which is a rectangular parallelepiped brush 10
The brush 10 is housed and guided by a resin so as not to transmit the vibration of the end frame 6 to the end frame 6. Reference numeral 8 denotes a coil spring, which is in contact with the brush holder 7 and the rear end of the brush 10 and forms an elastic member that presses the brush 10 in the direction of the commutator 3.
In the brush holder 7.

FIGS. 3 and 4 are illustrations of the brush of the present invention. The brush 10 is a diagonal two-layer brush, and 101 is a first resistance portion formed so as to gradually narrow from the front side to the rear side in the rotation direction of the commutator 3. Reference numeral 102 denotes a second resistance portion formed so as to gradually increase from the front side to the rear side in the rotation direction of the commutator 3, and has a larger resistance value than the first resistance portion. The brush 10 is numbered at each corner for explanation. Is a corner of the first resistance portion 101 having a low resistance, is a corner of the second resistance portion 102 having a high resistance, is a front corner in the rotation direction of the commutator 3, and is a rear corner. As shown by the outline contour lines, the height of each corner is from the highest to the lowest →
It is an inclined shape of →→. And this brush 1
In the contact surface of 0, the corner at the front end of the first resistance portion 101 first comes into contact with the commutator 3 before the brush wear, and the wear is unevenly worn as the wear progresses, so that the entire surface gradually comes into contact.

Next, the operation of the above configuration will be described. First, when the drive switch is turned on, the brush 10, the commutator 3, and the armature 1 are supplied with power from an external power supply (not shown) through the power supply connector, and the armature 1 is rotated, and the rotational driving force is transmitted from the rotating shaft 2 to the driven body. Is transmitted to and rotated. At this time, at the initial stage of shipping the motor, the contact surface of the brush 10 is such that the tip corner of the first resistance portion 101 first contacts the first commutation segment of the commutator 3 and gradually narrows rearward. Slide the triangular sliding surface to the rear corner. At this time, brush 10
As shown in FIG. 5A, the contact resistance during the sliding of the first commutation segment of the commutator 3 gradually increases toward each commutation termination as shown in FIG. A sudden current change due to a short-circuit current at the time of transition from the first rectifying segment to the second rectifying segment can be suppressed, sparks can be prevented from occurring, and vibration noise can be reliably prevented.

As the use of this motor progresses, uneven wear of the brush 10 progresses, and the sliding zone between the brush 10 and the commutator 3 becomes wider as shown in FIG. 4b. At this time, the sliding zone has a wide triangular shape at the contact tip and gradually narrows rearward, and the contact resistance during the sliding is reduced toward each commutation terminal as shown in FIG. The value gradually increases. Therefore, it is possible to suppress a sudden current change at the time of transition to each rectification segment, and to prevent noise.

Further, as the use of the motor progresses, uneven wear of the brush 10 progresses, and as shown in FIG.
Comes into contact with the commutator 3 and the sliding zone extends from the first resistance portion 101 to the second resistance portion 102. Then, brush 10
The uneven wear further progresses, and after 50 to 100 hours have elapsed from the start of use, the entire surface comes into contact as shown in FIG. In this case as well, the contact resistance during sliding of the brush 10 gradually increases toward each rectification end as shown in FIGS. It is possible to suppress the occurrence of sparks and to reliably prevent vibration noise.

As described above, since the contact surface of the brush 10 has an inclined shape and is brought into contact with the leading end corner of the front end of the first resistance portion 101 at the initial stage of motor shipment, the brush is slid on the commutator 3. Even when the commutator 3 and the brush 10 are assembled with a slight inclination due to dimensional variations, the commutator 3 can be brought into contact with the first resistance portion 101 having a low resistance value and slid first, and the resistance can be adjusted toward the commutation end. The value gradually increases, and stable operation can be secured from the initial stage of shipment.

FIGS. 6 and 7 show a second embodiment. In this embodiment, the height of the corner is changed from that of the first embodiment. The brush 11 was shaped so as to be point-symmetric as shown by the contour lines. The height of each corner is an inclined shape that becomes → in the descending order. Thereby, the brush 11
First, after the front corner contacts the commutator 3, the rear corner slides (the state of FIG. 7A). When the brush becomes unevenly worn, the corner becomes low and the sliding zone becomes large (the state shown in FIG. 7B). Thereafter, the entire surface slides due to the entire surface contact. Thus, at the end of the contact segment from the time of shipment of the motor, the contact portion always hits the high-resistance second resistance portion, and the contact resistance gradually increases in resistance toward each rectification termination. Becomes calm.
At the same time, stability of the vibration of the brush can be obtained.

FIGS. 8 and 9 show a third embodiment. This embodiment also differs from the first embodiment in the height of the corners. The brush 12 was shaped so as to be axisymmetric as indicated by the contour lines. Assuming that the intermediate point on the front side in the rotation direction of the commutator 3 is the intermediate point on the rear side, the heights of the corners are inclined in the order of increasing height →→→. As a result, the corner of the brush 12 first contacts the commutator 3, and then the corner slides (the state of FIG. 9A). Corners when the brush wears unevenly,
And the sliding zone becomes large (the state shown in FIG. 9B).
As the wear further advances, the intermediate point also slides (9).
FIG. C). Thereafter, the entire surface slides due to the entire surface contact. Thus, at the end of the contact segment from the time of shipment of the motor, the contact portion always hits the high-resistance second resistance portion, and the contact resistance gradually increases in resistance toward each rectification termination. Becomes calm. Commutator 3
Since the contact area on the front side in the rotation direction is large, the stability of the vibration of the brush can be obtained.

FIGS. 10 and 11 show a fourth embodiment. In this embodiment, the height of the corner is changed from that of the above-described third embodiment, and a brush 13 in which the first resistance portion and the second resistance portion are separated by a curve is used. The brush 13 was symmetrical with respect to the line as shown by the contour line, and was shaped so as to be point symmetrical. The height of each corner is an inclined shape in which the height is ascending in the order of →, and the central part is configured to be lower. Thereby, brush 1
Even if the sliding zone 3 is not limited to a triangle, the front, rear, left and right brushes can obtain stable sliding.

FIGS. 12 and 13 show a fifth embodiment. In the present embodiment, the first resistance section and the second
A brush 14 in which a curve dividing a resistance portion does not pass through a diagonal was used. The contour of the brush 14 is the same as that of the brush 13 described above.
The center is low. Thereby, even if the brush 14 does not limit the sliding zone to a triangle, the front, rear, left and right brushes can obtain stable sliding.

[0022]

As is apparent from the above description, according to the present invention, the low resistance portion on the front side in the rotational direction of the commutator mainly comes into contact first, and the contact resistance between the brush and the commutator from the time of shipment of the motor. By limiting the shape so that it starts at the low resistance portion and always separates at the high resistance portion, the effect of the two-layer brush can be reliably obtained, and vibration and electromagnetic noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a small motor according to a first embodiment.

FIG. 2 is an explanatory diagram of the brush device according to the first embodiment.

FIG. 3 is an explanatory diagram of a brush according to the first embodiment.

FIG. 4 is an explanatory diagram for explaining the operation of the first embodiment.

FIG. 5 is a contact resistance characteristic diagram of the first embodiment.

FIG. 6 is an explanatory diagram of a brush according to a second embodiment.

FIG. 7 is an explanatory diagram for explaining the operation of the second embodiment.

FIG. 8 is an explanatory view of a brush according to a third embodiment.

FIG. 9 is an explanatory diagram for explaining the operation of the third embodiment.

FIG. 10 is an explanatory view of a brush according to a fourth embodiment.

FIG. 11 is an explanatory diagram for explaining the operation of the fourth embodiment.

FIG. 12 is an explanatory view of a brush according to a fifth embodiment.

FIG. 13 is an explanatory diagram for explaining the operation of the fifth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Armature, 2 ... Rotating shaft, 3 ... Commutator, 4 ... Yoke housing, 5 ... Magnet, 6 ... End frame, 7
... brush holder, 8 ... coil spring, 10, 11,
12, 13, 14 ... brush, 101 ... first resistance part, 1
02 ... second resistance part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H613 AA01 BB04 BB15 BB27 GA10 GB01 GB05 GB08 GB09 GB12 KK01 PP03 QQ05 QQ06 SS05 SS07

Claims (3)

[Claims] 1. A small motor having a stator and a rotor, wherein the stator is provided with a brush having a substantially rectangular parallelepiped shape, wherein the rotor has a rotating shaft, and is substantially equal to the brush mounted on the rotating shaft. A commutator composed of a plurality of commutator pieces having a width, and a winding connecting adjacent commutators to each other, wherein the brush has a cross section viewed from a commutator side of the rotor in a forward direction in a rotor rotation direction. A first resistance portion formed so as to be gradually narrowed from a side toward a rear side, and a cross section viewed from a commutator side of the rotor is formed so as to be gradually widened from a front side to a rear side in a rotor rotation direction, and A second resistance portion having a larger resistance value than the first resistance portion, and a contact surface of the brush with the commutator has at least a front end in the rotor rotation direction of the first resistance portion before the brush wears. Commutator first Contact is, a small motor, characterized in that with gradually extending the entire surface contact by uneven wear due to the progress of brush abrasion was gradually increasing slope shape resistance toward each commutation end. 2. The small motor according to claim 1, wherein said wear contact surface forms a substantially triangular shape at an initial stage of wear. 3. The small motor according to claim 1, wherein before the brush is worn, an end of the first resistance portion other than a front end in the rotor rotation direction is connected to the rotor of the first resistance portion. A small motor having the same contact height as the front end in the rotation direction.