JP2008220046A - Speed switching motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent vibration and noise or the like of a speed switching motor. <P>SOLUTION: The speed switching motor has a stator 11 for forming a field magnetic flux, an armature 14 having a coil wire 19 wound therearound, a commutator 20 in which the coil wire 19 is connected to a plurality of segments 23 annularly arrayed while sandwiching each insulating part 25, a first brush 32 and a second brush 33 that are brought into sliding contact with the commutator 20 at positions apart by 180 degrees in the circumferential direction, and a third brush 34 brought into sliding contact with the commutator 20 at a position deviated from the brushes 32, 33 in the circumferential direction. Wide insulating parts 25A and narrow insulating parts 25B are arrayed in the commutator 20 at prescribed intervals. A non-conductive dummy segment 26 is arranged in each of the wide insulating parts 25A. It is possible to reduce a closed circuit formation period of the coil wire due to a short-circuit of the segments of the third brush. Therefore, it is possible to prevent vibration and noise or the like by suppressing a whirling force of the armature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a speed switching motor capable of switching between at least two speeds of low speed operation and high speed operation. About things.

  In general, in a wiper motor used in a wiper device that wipes raindrops, dust, etc. adhering to a windshield of an automobile, the driving speed according to the amount of rain, i.e., in the case of light rain such as drizzle, etc. It is configured so that low speed operation and high speed operation during heavy rain can be selected.

As such a wiper motor capable of speed switching, the one disclosed in Patent Document 1 is known.
That is, the wiper motor includes a first brush, a second brush, and a third brush, and these three brushes have the same circumferential width and are arranged on the same surface of the commutator (commutator). They are opposed to each other at an angle, and by switching operation, power is supplied to the armature through the first brush and the second brush, and the armature is supplied through the second brush and the third brush to operate at high speed. You can do that.
Japanese Patent Laid-Open No. 2005-12945

  However, in the wiper motor described above, during the low speed operation of the wiper motor, the high speed operation brush shorts adjacent segments in the circumferential direction to form a closed circuit of the coil wire connected between the segments. There is a problem that the armature's swaying force is generated in order to generate unbalance in the rotating magnetic field or to apply a brake torque to the armature, resulting in problems such as vibration and noise of the wiper motor. .

  An object of the present invention is to provide a speed switching motor capable of preventing the harmful effects of vibration and noise.

Typical means for solving the above-described problems are as follows.
(1) A speed-switching motor that can switch the rotation speed,
A stator forming a field device;
An armature in which a coil wire is wound around a core;
A plurality of segments are annularly arranged in the circumferential direction with an insulating portion interposed therebetween, and each segment is electrically connected to each segment, and a commutator that rotates integrally with the armature,
A pair of brushes fixed to the main body side of the electric motor and in sliding contact with the commutator at positions 180 degrees apart from each other in the circumferential direction;
A third brush that slidably contacts the commutator at a position displaced in the circumferential direction with respect to the pair of brushes,
The speed switching motor, wherein a circumferential width of at least one insulating portion of the commutator is set wider than a circumferential width of other insulating portions.

  According to said (1), the insulation part with a wide circumferential direction width | variety is arrange | positioned at a commutator, and it suppresses thru | or suppresses the closed circuit formation time of the coil by the short circuit of the adjacent segments of a 3rd brush. As a result, the swinging force of the armature can be suppressed, and adverse effects such as vibration and noise of the speed switching motor can be prevented.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the present embodiment, the speed switching motor according to the present invention is used in a wiper motor that drives a wiper device, as shown in FIG.
That is, the wiper motor 1 shown in FIG. 1 includes a speed switching motor (hereinafter referred to as a drive motor) 10 and a worm gear reduction device 2 according to the present embodiment.

As shown in FIG. 1, the worm gear reduction device 2 includes a gear case 3, and the gear case 3 is formed of a die-cast processed product or the like.
A shaft, which will be described later, is inserted into the gear case 3, and a worm 4 is integrally provided at the tip of the shaft. A worm wheel 5 is meshed with the worm 4. A drive gear 7 is meshed with the worm wheel 5 via an intermediate gear 6, and an output shaft 8 is fixed on the central axis of the drive gear 7.
A crank 9 (see an imaginary line in FIG. 1) interlocked with the wiper arm is fitted to the protruding end portion of the output shaft 8 and is fitted into a tapered portion formed at the protruding end portion, and a nut is screwed into a male screw portion (not shown). Are connected.

As shown in FIG. 1, the drive motor 10 includes a stator 11 that forms a field device, and the stator 11 is formed in a cylindrical shape with one end closed by a magnetic material such as iron and the other end opened. The yoke 12 and a pair of magnets 13 arranged concentrically on the inner peripheral surface of the yoke 12 and fixed thereto.
The pair of magnets 13 and 13 are permanent magnets having an arc-shaped cross section, and are configured as an inner N pole / outer S pole and an inner S pole / outer N pole, and are opposed to the inner peripheral surface of the yoke 12. Is arranged.

On the center line of the stator 11, an armature 14 is pivotally supported so as to be opposed to the magnets 13 and 13 through a minute gap (air gap).
That is, the shaft 15 of the armature 14 is pivoted on the center line of the yoke 12 and is rotatably supported by the closing wall side bearing 16 and the opening side bearing 17 fixed to the gear case 3.
A core 18 is fixed to the outer periphery of the intermediate portion of the shaft 15, and a coil wire 19 is wound around the core 18.
In the present embodiment, the armature 14 is composed of twelve magnetic poles by a core 18 and a wound coil wire 19.

  As shown in FIG. 1, a commutator 20 formed in a generally cylindrical shape is provided on the outer periphery of one side (the worm side in FIG. 1) of the armature 14 of the shaft 15, and the brush contact surface is the shaft. It is arranged and fixed so as to be concentric with 15.

  As shown in FIG. 2A and FIG. 2B, the commutator 20 includes a base 21 formed in a cylindrical shape using an insulating resin. A shaft hole 22 is formed on the center line of the base 21. The commutator 20 is fixed to the shaft 15 by press-fitting the shaft 15 into the shaft hole 22.

Twelve segments 23 formed in a rectangular shape are arranged on the outer peripheral surface, which is the brush contact surface of the base 21, with a predetermined interval (30 degrees) in the circumferential direction.
As shown in FIG. 2B, the segments 23 are respectively fixed to the base 21 by anchoring a anchoring portion (anchor portion) 23 a to the base 21. A riser 24 is integrally formed at one end of the segment 23 in the longitudinal direction of the rectangle. The riser 24 is folded back in the U shape radially outward and protrudes from the outer peripheral surface of the base 21.
After the coil wire 19 is hooked on the riser 24, each riser 24 is electrically connected by fusing.

As shown in FIG. 2A and FIG. 3, an insulating portion 25 that electrically insulates the adjacent segments 23, 23 is formed between the adjacent segments 23, 23 of the base 21. Yes. In principle, the insulating portion 25 is constituted by an air gap (slit).
In the present embodiment, twelve segments 23 are arranged in an annular shape, so that twelve insulating portions 25 are arranged.
Among the twelve insulating portions 25, the circumferential width Wa of the six insulating portions 25 is set wider than the circumferential width W of the other six insulating portions 25.
Insulators having a wide circumferential width (hereinafter referred to as a wide insulating portion 25A) and other insulating portions (hereinafter referred to as a narrow insulating portion 25B) are alternately arranged in the commutator 20.
That is, the number of wide insulating portions 25A is set so as to satisfy the following expression (1), and the wide insulating portions 25A and the narrow insulating portions 25B are regularly arranged at a constant period.
Nd = Ns / m (1)
In this formula (1), Ns is the number of segments, Nd is the number of wide insulating portions, and m is a divisor of Ns.
In the present embodiment, Ns = 12, m = 2, and Nd = 6.

As shown in FIG. 2A and FIG. 3, one dummy segment 26 is arranged in the wide insulating portion 25A.
Each dummy segment 26 is electrically insulated from the segments 23, 23 on both sides, and is electrically nonconductive without being grounded.
That is, as shown in FIG. 2A, slits 27, 27 are formed on both sides of the dummy segment 26, and the dummy segment 26 is divided into segments 23, 23 by the slits 27, 27 on both sides. Insulated from.
As shown in FIG. 2B, the dummy segments 26 are respectively fixed to the base 21 by anchoring the anchoring portion 26 a to the base 21.

A method for manufacturing the cylinder type commutator 20 according to the above configuration will be described.
A cylindrical body, which is a material, is formed in advance by rolling a copper plate having a riser 24 formed at the end thereof into a cylindrical shape through a plurality of steps.
Subsequently, a throwing portion 23a of the segment 23 and a throwing portion 26a of the dummy segment 26 are formed at the axial end portion on the inner peripheral surface of the cylindrical body.
Next, the inside of the cylindrical body is filled with an insulating resin, and the base 21 and the shaft hole 22 are formed.
Thereafter, slits 27, 27 on both sides of the dummy segment 26 for forming the air gap which is the narrow insulating portion 25B and the dummy segment 26 for forming the wide insulating portion 25A are axially formed on the cylindrical body on which the base 21 is molded. Cut from one end to the other and deeper than the thickness of the cylinder.
According to the above commutator manufacturing method, the cylinder type commutator 20 in which the wide insulating portion 25A and the narrow insulating portion 25B are mixed can be mass-produced efficiently.

The coil wires 19 connected to the risers 24 of the twelve segments 23 are wound around the slots between the twelve teeth of the armature 14 as shown in the developed view of FIG. Thus, the armature 14 constitutes a coil having 12 poles.
FIG. 3 is an exploded view of the armature, in which 12 segments 23 and 12 teeth 28 are numbered 1 to 12, respectively.
For example, in FIG. 3, the coil wire 19 a is unwound from the riser 24 of the third segment 23, and is rotated a plurality of times into a slot 29 a between the first and second teeth and a slot 29 f between the sixth and seventh teeth. After being wound to form a coil, it is connected to the riser 24 of the fourth segment 23.

As shown in FIG. 1, a brush device 30 is installed outside the commutator 20 fixed to the shaft 15.
The brush device 30 includes a brush holder stay 31 formed of a flat plate shape using an insulating resin. The brush holder stay 31 is fixed to the bracket 10 a of the drive motor 10.
The main surface of the brush holder stay 31 on the side of the commutator 20 includes a first brush 32 and a second brush 33 that are a pair of brushes that are in sliding contact with the commutator 20 at positions 180 degrees apart from each other in the circumferential direction, and one first brush. A third brush 34 (see FIGS. 2 and 3) that is in sliding contact with the position 32 in the circumferential direction is disposed.
The brushes 32, 33, and 34 are accommodated in the brush holders 35 so as to be slidable with the commutator 20, and the brush commutator surface of the commutator 20 (brush contact surfaces of the segment 23 and the insulating portion 25) by the brush spring 36. It is pressed.

As shown in FIG. 2 (a) and as shown in FIG. 3, the first brush 32 and the second brush 33 are arranged at positions 180 degrees apart from each other in the circumferential direction. The third brush 34 is at a position away from the first brush 32 in the circumferential direction by a predetermined angle (63 degrees in the present embodiment) and is spaced from the second brush 33 in the circumferential direction by a predetermined angle (117 degrees in the present embodiment). ) It is located at a distance.
As shown in FIG. 3, the first brush 32 and the third brush 34 are connected to the positive side of the battery 41 of the drive electric circuit 40 of the drive motor 10, and the second brush 33 is a part of the wiper switch. Are connected to the negative side via a speed changeover switch 42 constituting the.

As shown in FIGS. 2A and 3, the first brush 32, the second brush 33, and the third brush 34 are made of the same material and have the same dimensions. Therefore, the contact area with respect to the commutator 20 of the 1st brush 32, the 2nd brush 33, and the 3rd brush 34 is the same.
The dimension in the circumferential width of the first brush 32, the second brush 33, and the third brush 34 is set to a predetermined dimension that straddles two segments 23 but does not straddle three.
The circumferential width Wb of the third brush 34 is set to be equal to or smaller than the circumferential width Wa of the wide insulating portion 25A, that is, Wb ≦ Wa.

  Next, the operation of the wiper motor according to the above configuration will be described mainly with respect to the operation of the drive motor commutator.

When the speed change switch 42 is turned on to the first brush 32 side, which is the low speed operation side of the wiper device, by the operation of the wiper switch by the driver, the current from the battery 41 is changed to the speed change switch 42 → first brush 32 → segment. 23 → coil wire 19 → the second brush 33 separated by 180 ° → the earth flows, whereby a predetermined magnetic pole of the armature 14 is excited.
The armature 14 rotates when the magnetic flux of the excited predetermined magnetic pole cuts the field magnetic flux of the stator 11.
When the armature 14 rotates 30 degrees, the contact positions of the first brush 32 and the second brush 33 with respect to the commutator 20 are relatively advanced by one segment 23, so that the magnetic pole excited by the armature 14 is 30 degrees in the circumferential direction. move on.
In this way, the armature 14 continues to rotate as the brush device 30, the commutator 20, and the coil wire 19 form a rotating magnetic field in a self-controlling manner.

Similarly, when the speed changeover switch 42 is turned on to the third brush 34 side which is the high speed operation side of the wiper device by the operation of the wiper switch, the current from the battery 41 is changed to the speed changeover switch 42 → the third brush 34 → the segment. 23 → coil wire 19 → second brush 33 separated by 117 degrees → ground, and thereby a predetermined magnetic pole of the armature 14 is excited.
The armature 14 rotates when the magnetic flux of the excited predetermined magnetic pole cuts the field magnetic flux of the stator 11.
When the armature 14 rotates 30 degrees, the contact positions of the third brush 34 and the second brush 33 with respect to the commutator 20 are relatively advanced by one segment 23, so that the magnetic pole excited by the armature 14 is 30 degrees in the circumferential direction. move on.
Thus, the armature 14 continues to rotate as the brush device 30, the commutator 20, and the coil wire 19 form a rotating magnetic field.

The rotation of the shaft 15 accompanying the rotation of the armature 14 by the above action is decelerated by the worm gear reduction device 2 and transmitted to the output shaft 8.
The output shaft 8 rotates a crank 9 interlocked with a wiper arm (not shown).
The crank 9 wipes the front window glass by converting the rotational movement of the armature 14 into a reciprocating rocking movement that reciprocally rocks the wiper arm by a link mechanism (not shown).

By the way, when the speed changeover switch 42 is turned on to the first brush 32 side, which is the low speed operation side of the wiper device, the third brush 34 is in a non-conducting state and therefore does not form a rotating magnetic field.
However, the third brush 34 short-circuits the adjacent segments 23, 23 to form a closed circuit of the coil wire 19 connected to both the segments 23, 23, thereby causing imbalance due to the rotating magnetic field of the armature 14. At the same time, a swinging force is generated in the armature 14 to urge the armature 14 with a brake torque. As a result, adverse effects such as vibration of the wiper motor, noise, and deterioration of output characteristics are derived.
Such a whirling force is generated due to a difference in resistance in the parallel circuit and an unbalanced conductor distribution, and a brake torque is generated in a closed circuit by the third brush 34 in a different polarity, and the motor rotates. Thus, an electromotive force is generated in the closed circuit, and a force generated by the electromotive force is generated (brake) in a direction opposite to the rotation direction of the motor.

  In the present embodiment, since the wide insulating portion 25A is arranged, the period during which the third brush 34 short-circuits the adjacent segments 23 across the wide insulating portion 25A is shortened. The period for forming the closed circuit of the coil wire 19 connected to the segments 23, 23 on both sides of the insulating portion 25A can be shortened, and an unbalance can be generated in the rotating magnetic field of the armature 14, or the armature 14 can be braked. The phenomenon that exerts torque can be suppressed or suppressed.

FIG. 4 is a graph showing the effect of the present embodiment in comparison with the conventional example, where (a) shows the electromagnetic force Lissajous waveform, and (b) shows the relationship between the electromagnetic force in the Fx direction and the armature rotation angle. Is shown.
In FIG. 4A, the vertical axis indicates the force (Newton) in the Y direction, and the horizontal axis indicates the force (Newton) in the X direction. The solid line curve shows the case of a conventional example (speed switching motor having a commutator in which insulating portions having a constant circumferential width are arranged), and the broken line curve shows the case of the present embodiment.
As can be seen from FIG. 4A, in the case of the present embodiment as well, the whirling force is generated as in the conventional example.
In FIG. 4B, the vertical axis represents the force (Newton) in the X direction, and the horizontal axis represents the rotation angle (deg). The solid line waveform indicates the case of the conventional example, and the broken line waveform indicates the case of the present embodiment.
According to FIG. 4B, it can be seen that the number of generations of electromagnetic force in the case of the present embodiment is halved compared to that in the case of the conventional example.
From this result, it can be considered that the frequency of vibration and motor noise generated by the whirling force can be reduced by half.

Here, if the rotational speed of the speed switching motor is 3000 rpm, the fundamental frequency component due to the swinging force is 3000 rpm / 60 × 12 (number of occurrences of swinging) = 600 Hz in the case of the conventional example.
On the other hand, in the case of the present embodiment, 3000 rpm / 60 × 6 (number of occurrences of swinging) = 300 Hz.
That is, in the case of the present embodiment, the swing frequency can be reduced by half compared to the conventional example.

When the speed changeover switch 42 is turned on to the third brush 34 side, which is the high speed operation side of the wiper device, the first brush 32 is in a non-conductive state, but does not form a rotating magnetic field. The first brush 32 forms a closed circuit of the coil wire 19 connected to both the segments 23 and 23 by short-circuiting the adjacent segments 23 and 23.
However, since almost no electromotive force is generated in the closed circuit in which the first brush 32 and the second brush 33 are respectively straddling the segment 23, there is almost no generation of brake torque.

  According to the embodiment, the following effects can be obtained.

1) By periodically arranging wide and narrow insulating parts on the commutator, the period during which the third brush shorts adjacent segments across the insulating part is shortened, and both sides sandwiching the insulating part Since the period in which the portion of the coil wire connected to the segment forms a closed circuit can be shortened, an unbalance can be generated in the rotating magnetic field of the armature, and the phenomenon of applying a brake torque to the armature can be suppressed.

2) By preventing the unbalance of the rotating magnetic field and the phenomenon of applying brake torque to the armature, it is possible to prevent the armature's swinging force from being suppressed. .

3) By placing the dummy segment in the wide insulating part formed by the air gap (slit), the air gap of the wide insulating part can be filled with the dummy segment, so each brush is prevented from falling into the wide insulating part can do.

4) By arranging the dummy segment formed with the segment in the wide insulating part, it is possible to efficiently mass-produce commutators in which a wide insulating part and a narrow insulating part are mixed, thus increasing the manufacturing cost of the commutator. Can be prevented.

  FIG. 5 is a development view showing an armature of the drive motor of the wiper device according to the second embodiment of the present invention.

This embodiment is different from the first embodiment described above in that the number of wide insulating portions 25A is set by substituting m = 3 into the above-described equation (1), and four wide insulating portions. 25A is that it is regularly arranged with a fixed period of every three insulating portions 25B that are narrow.
The number of wide insulating portions 25A in the first embodiment is six, whereas the number of wide insulating portions 25A in the present embodiment is as small as four. The decrease in is less.
However, in the case of the first embodiment, since the fundamental frequency component is halved, the harmonic component may overlap with other vibration components.
In such a case, according to the present embodiment, the harmonic component of the fundamental frequency component is set so as not to overlap the slot order frequency component and the harmonic component of the speed switching motor.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  For example, the number of segments of the commutator is not limited to 12, and the number of wide insulating portions is not limited to 6 or 4. These numbers may be set so as to satisfy the above-described equation (1).

  A wide insulating part is not limited to a dummy segment disposed in a wide insulating part (air gap), but may be configured by filling an insulating resin in a wide air gap (slit), or a drop of a brush. If it can be prevented, it may be constituted by a slit (air gap).

  The commutator is not limited to a cylindrical shape, i.e., a cylinder type commutator, but may be a disk shape, i.e., a disk type commutator.

  In the above-described embodiment, the speed-switchable motor has been shown to be capable of switching to a two-stage operation speed of low speed operation and high-speed operation. However, the present invention is not limited to this, and is switched to an operation speed of three or more stages. It can also be applied to possible speed-switching motors. In this case, two or more third brushes are provided.

  In the above-described embodiment, the case where the present invention is applied to a wiper motor used in a vehicle wiper device has been described. However, the present invention is not limited to this, and may be applied to all speed-switching motors having brushes for each speed. Can do.

It is a partially cut front view which shows the wiper motor which is one embodiment of this invention. The commutator is shown, (a) is front sectional drawing, (b) is sectional drawing which follows the bb line of (a). It is an expanded view which shows an armature. It is a graph which compares the effect of this Embodiment with a prior art example, (a) has shown the electromagnetic force Lissajous waveform, (b) has shown the relationship between the electromagnetic force of Fx direction, and an armature rotation angle. Yes. It is an expanded view which shows the armature of the drive motor of the wiper apparatus which is 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wiper motor, 2 ... Worm gear reduction device, 3 ... Gear case, 4 ... Worm, 5 ... Worm wheel, 6 ... Intermediate gear, 7 ... Drive gear, 8 ... Output shaft, 9 ... Crank, 10 ... Drive motor (speed change) Motor, 11 ... stator, 12 ... magnet, 14 ... armature, 15 ... shaft, 16 ... blocking wall side bearing, 17 ... opening side bearing, 18 ... core, 19 ... coil wire,
DESCRIPTION OF SYMBOLS 20 ... Commutator, 21 ... Base, 22 ... Shaft hole, 23 ... Segment, 23a ... Throwing part, 24 ... Riser, 25 ... Insulating part, 25A ... Wide insulating part, 25B ... Narrow insulating part, 26 ... Dummy segment, 26a ... Throwing part, 27 ... slit, 28 ... teeth, 29 ... slot,
DESCRIPTION OF SYMBOLS 30 ... Brush apparatus, 31 ... Brush holder stay, 32 ... 1st brush (one of a pair of brush), 33 ... 2nd brush (the other of a pair of brush), 34 ... 3rd brush, 35 ... Brush holder, 36 ... Brush spring,
40: driving electric circuit, 41: battery, 42: changeover switch.

Claims (3)

A speed-switching motor capable of switching the rotation speed,
A stator forming a field device;
An armature in which a coil wire is wound around a core;
A plurality of segments are annularly arranged in the circumferential direction with an insulating portion interposed therebetween, and each segment is electrically connected to each segment, and a commutator that rotates integrally with the armature,
A pair of brushes fixed to the main body side of the electric motor and in sliding contact with the commutator at positions 180 degrees apart from each other in the circumferential direction;
A third brush that slidably contacts the commutator at a position displaced in the circumferential direction with respect to the pair of brushes,
The speed switching motor, wherein a circumferential width of at least one insulating portion of the commutator is set wider than a circumferential width of other insulating portions.   When the number of segments is Ns and the divisor of Ns is m, the number Nd of insulating portions having a wide circumferential width is set to satisfy Nd = Ns / m, and the circumferential width is 2. The speed switching motor according to claim 1, wherein the wide insulating portion and the other insulating portion are regularly arranged at a constant cycle.   3. The speed switching motor according to claim 1, wherein a non-conductive dummy segment is disposed in the coil wire in the insulating portion having a wide circumferential width.

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