JP2004248460A - Direct-current motor with brush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a lock current value at high-speed operation, and strive for the suppression of inverted torque at low speed and the improvement of rectifying capability at high speed in a dc motor with brushes. <P>SOLUTION: The dc motor with brushes comprises a stator which has two-pole field magnets, and a rotor which is rotatably disposed in the stator and has an armature coil and a commutator connected with the armature coil. The motor is provided with a paired brushes 2 for low-speed driving and a paired brushes 3 for high-speed driving. The paired brushes 2 comprise a positive-pole brush 2a and a negative-pole brush 2b, and the paired brushes 3 comprise a positive-pole brush 3a and a negative-pole brush 3b. The paired brushes 3 for high speed is eccentrically disposed by a predetermined angle in the positive angular direction relative to the brush pair 2 for low speed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor with a direct current brush, and more particularly to a technique that is effective when applied to a motor for a wiper device.
[0002]
[Prior art]
As a driving source of a wiper device for a vehicle such as an automobile, a DC brush motor having a two-pole field magnet has been widely used. FIG. 4 is an explanatory diagram showing a circuit configuration of such a conventional motor for a wiper device, FIG. 5A is an explanatory diagram showing a relationship between a winding and a brush in the motor of FIG. 4, and FIG. FIG. 4 is an explanatory diagram showing a brush arrangement in the motor of FIG.
[0003]
As shown in FIGS. 4 and 5, a conventional DC brush motor 51 (hereinafter abbreviated as motor 51) includes a common positive brush 52 and two negative brushes 53 and 54 (hereinafter, brushes 52, 53, and 52). 54 (abbreviated as 54). Brush 54 is disposed only mechanical angle theta ₁ advanced position with respect to the brush 53. The brushes 52 to 54 are in sliding contact with the commutator 55. The commutator 55 is connected to an armature coil 56, and a two-pole field magnet 57 is provided outside the armature coil 56. The brushes 53 and 54 are used for low-speed driving and high-speed driving, respectively, and by switching between them, the motor 51 is switched between two driving modes of a low speed and a high speed in accordance with the operation mode of the wiper device.
[0004]
[Problems to be solved by the invention]
By the way, as the size of the wiper system increases, the size of the wiper motor also increases year by year. However, as the size of the motor increases, the lock current of the motor increases accordingly. For this reason, the diameter of the harness to be used and the current capacity of the fuse are increased, which causes a problem that the weight of the vehicle body and the cost of the apparatus are further increased.
[0005]
In addition, when the low-speed brush 53 is used, the high-speed brush 54 is located at a position where the magnetic flux changes greatly, and thus an electromotive force is generated in the coil short-circuited by the brush 54 by the magnetic flux of the field magnet 57. For this reason, a short-circuit current flows through the short-circuit coil, thereby generating a reversing torque in the rotor, and thus causing a problem that the motor characteristics deteriorate. Further, there is a problem that current ripple is disturbed by the short-circuit current, which causes torque unevenness.
[0006]
On the other hand, as shown in FIG. 5A, the high-speed brush 54 short-circuits one of the circuits by the low-speed brush 53. That is, between the brush 52 and the brush 54, a circuit X (paths B, A, and C) extending from the brush 53 to the brush 54 and a circuit Y (path D) extending directly from the brush 52 to the brush 54 are established. I do. As can be seen from FIG. 5A, since there is a resistance difference between the two circuits X and Y and an electromotive force difference occurs between AB and CD, a circulating current flows between the brushes 52 and 54 and adversely affects rectification. Effect. In particular, in the case of a high voltage, the influence is large, and the improvement has been required.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to reduce a lock current value at the time of high-speed operation in a DC brush motor, suppress reversal torque at a low speed, and improve rectification at a high speed.
[0008]
[Means for Solving the Problems]
A DC brush motor according to the present invention is a DC brush comprising: a stator having a field magnet; and a rotor rotatably disposed in the stator and having an armature coil and a commutator connected to the armature coil. A first brush pair including a first positive electrode brush and a first negative electrode brush slidably contacting the commutator, and a predetermined angle from the first positive electrode brush and the second negative electrode brush slidably contacting the commutator. A second brush pair including a second positive electrode brush and a second negative electrode brush, which are arranged in the same manner.
[0009]
In the present invention, since the first brush pair and the second brush pair each having a pair of positive and negative brushes are provided, the lock current value can be reduced as compared with a conventional three-brush motor. it can. Therefore, the current capacity of the harness and the fuse can be suppressed, and the weight and cost of the vehicle body can be reduced.
[0010]
Also, since the deviation angle can be made smaller than that of the conventional motor, a short-circuit coil is formed avoiding the position where the magnetic flux change is large, the electromotive force due to the magnetic flux of the field magnet can be reduced, and the reversing torque can be reduced. It becomes. Further, the armature coil resistance value can be the same regardless of which brush pair is used, so that a difference in electromotive force can be eliminated. Therefore, it is possible to eliminate the adverse effect at the time of commutation due to the circulating current generated between the brushes, thereby reducing the brush wear and improving the durability.
[0011]
In the DC brush motor, the first brush pair may be used for low-speed driving, and the second brush pair may be used for high-speed driving. Further, in the DC brush motor, the first brush pair may be arranged in a more advanced direction than the second brush pair. The DC brushed motor may be a DC brushed motor having a two-pole field magnet.
[0012]
Further, the DC brushed motor may be an electric motor used for a wiper device for an automobile. In the brush motor according to the present invention, the four-brush configuration makes it possible to reduce the electromagnetic force at the time of the DC brush-motor low speed as compared with the three-brush configuration. Therefore, when the motor is used as a wiper motor, noise and vibration are reduced, and the sound of the wiper device can be reduced.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a circuit configuration of a DC brush motor for a wiper device according to an embodiment of the present invention. FIG. 2A is an explanatory diagram showing a relationship between a winding and a brush in the motor of FIG. FIG. 2B is an explanatory diagram showing the brush arrangement in the motor of FIG.
[0014]
As shown in FIG. 1, a DC brush motor 1 (hereinafter abbreviated as motor 1) is provided with two brush pairs 2 and 3. The brush pair 2 (first brush pair) is used for low-speed driving, and is provided with one positive brush 2a (first positive brush) and one negative brush 2b (first negative brush). On the other hand, the brush pair 3 (second brush pair) is used for high-speed driving, and one positive brush 3a (second positive brush) and one negative brush 3b (second negative brush) are provided (hereinafter, positive brush). The brush 3a and the like are simply abbreviated as the brush 3a).
[0015]
As shown in FIG. 2B, the brushes 2a and the like are in sliding contact with the commutator 4. The commutator 4 is connected to the armature coil 5 and forms a rotor 6. The rotor 6 is housed in a stator 8 to which a two-pole field magnet 7 is attached. Further, the motor 1 is connected to the battery 9 and the switch 11 switches between OFF, Low, and High. A relay 12 is interposed between the battery 9 and the motor 1. The relay 12 is linked with the switch 11, and when the switch 11 is switched to High, the positive brushes 2a and 3a connected to the battery 9 are switched.
[0016]
The brushes 3a and 3b of the brush pair 3 are arranged at positions advanced with respect to the brushes 2a and 2b of the brush pair 2. The deviation angle between the brushes having the same polarity (between the brushes 2a and 3a, between the brushes 2b and 3b) is smaller than the deviation angle θ ₁ (for example, 63 °) of the conventional high-speed brush indicated by the broken line (θ ₂ (63 °)). For example, 45 °). Since the motor 1 has a configuration in which two brush pairs are provided, by moving the two high-speed brushes relatively, the bias angle per brush can be reduced while maintaining the same characteristics. It is smaller than the motor.
[0017]
In the motor 1, by switching the brush pairs 2 and 3, the driving mode can be switched between a low speed and a high speed in accordance with the operation mode of the wiper device. When the high-speed brush pair 3 is used, the magnetic flux of the field magnet 7 crosses the energized winding obliquely compared to when the brush pair 2 is used. Therefore, the amount of magnetic flux passing through the winding is reduced, and the rotational resistance due to the self-inductance is reduced. Therefore, when the brush pair 3 is used, the rotation speed of the motor 1 increases as in the advanced angle state, and the high speed mode is set.
[0018]
At low speed, the brush pair 2 for low speed is used. At this time, the coil is also short-circuited by the brush pair 3 in the motor 1. However, as described above, since the bias angle of the brush is smaller than that of the conventional motor 51, a short-circuit coil is formed avoiding a position where a change in magnetic flux is large. Therefore, the electromotive force due to the magnetic flux of the field magnet 7 can be reduced, and the reversal torque can be reduced. In addition, at low speed, the electromagnetic force is increased in the case of the three-brush configuration as shown in FIG. 5, whereas the electromagnetic force can be reduced in the motor 1 having the four-brush configuration. Therefore, when the motor is used as a wiper motor, noise and vibration are reduced, and the sound of the wiper device can be reduced.
[0019]
On the other hand, at the time of High speed, the brush pair 3 for high speed is used. At this time, as shown in FIG. 2A, the brush 3b is also interposed between the brushes 3a and 3b via the brush 2b. And a circuit Q (paths B and D) reaching the brush 3b via the brush 2a. However, as can be seen from FIG. 2A, in the motor 1, there is no resistance difference between the two circuits P and Q, and no electromotive force difference occurs between AB and CD. For this reason, it is possible to eliminate the adverse effect at the time of commutation due to the circulating current generated between the brushes 3a and 3b, thereby reducing the brush wear and improving the durability.
[0020]
In the motor 1, the combined resistance between the brushes 3a and 3b is larger than the combined resistance between the brushes 52 and 54 in FIG. That is, assuming that the resistance value between AB and CD is r ₀ and the divided resistance value between CDs by the brush 54 is r ₁ , r ₂ (r ₁ + r ₂ = r ₀ ), the brush in the case of FIG. the combined resistance value _{R 1} between 52 and _54, a _{R 1 = r 2 (r 0} + r 1) / 2r 0. In contrast, in the case of FIG. 2 (a), the combined resistance value _{R 2} between the brushes 3a, 3b _{becomes R} 2 _{= r} 0/2. Comparing R ₁ and _{R 2, R 2 -R 1 =} r 0 / 2- {r 2 (r 0 + r 1) / 2r 0} = r 1 2 / 2r 0> 0 , and the better the _{R 2} R _It becomes larger than ₁ . Accordingly, the lock current value of the motor 1 at the time of the high speed becomes smaller than that of the motor 51, and becomes the same as that at the time of the low speed.
[0021]
FIG. 3 is an explanatory diagram showing characteristics of the motor 1. As shown by the solid line in FIG. 3, the lock current value of the motor 1 at the time of the High speed is smaller than the lock current value of the conventional motor 51 shown by the broken line. Therefore, the current capacity of the harness and the fuse can be suppressed, and the weight and the cost of the vehicle body can be reduced even though the motor has the High speed mode.
[0022]
The present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention.
For example, the inter-pole brush (interproximal brushes 2a, 3a, brushes 2b, among 3b) shows the case of 45 ° as an example of a biasing angle theta ₂ of, but not limited to that value 45 °. Further, the characteristics in FIG. 4 are merely examples, and the current amount and the number of rotations are not limited to these characteristics.
[0023]
Furthermore, in the above-described embodiment, an example is shown in which the motor according to the present invention is applied to a wiper device for a vehicle, but it is also possible to apply the motor to another rotating electric machine. For example, the present invention is also effective for other in-vehicle motors for automobiles, motors used in industrial machines, home appliances, IT devices, and the like.
[0024]
【The invention's effect】
According to the DC brush motor of the present invention, since the first brush pair and the second brush pair each having a pair of positive and negative brushes are provided, the lock current value can be reduced as compared with a conventional three-brush motor. Can be reduced. Therefore, the current capacity of the harness and the fuse can be suppressed, and the weight and cost of the vehicle body can be reduced.
[0025]
In addition, since the deviation angle can be reduced as compared with the conventional DC brush motor, a short-circuit coil is formed avoiding a position where the magnetic flux change is large, the electromotive force due to the magnetic flux of the field magnet can be reduced, and the reversing torque can be reduced. It becomes possible. Further, the armature coil resistance value can be the same regardless of which brush pair is used, so that a difference in electromotive force can be eliminated. Therefore, it is possible to eliminate the adverse effect at the time of commutation due to the circulating current generated between the brushes, thereby reducing the brush wear and improving the durability.
[0026]
In addition, at low speed, the electromagnetic force increases in the case of the three-brush configuration, but the electromagnetic force can be reduced by the four-brush configuration. Therefore, when the motor is used as a wiper motor, noise and vibration are reduced, and the sound of the wiper device can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a circuit configuration of a DC brush motor for a wiper device according to an embodiment of the present invention.
2A is an explanatory diagram showing a relationship between a winding and a brush in the DC brush motor of FIG. 1, and FIG. 2B is an explanatory diagram showing a brush arrangement in the DC brush motor of FIG.
FIG. 3 is an explanatory diagram showing characteristics of the DC brush motor of FIG. 1;
FIG. 4 is an explanatory diagram showing a circuit configuration of a conventional DC brush motor for a wiper device.
5A is an explanatory diagram showing a relationship between a winding and a brush in the DC brush motor of FIG. 4, and FIG. 5B is an explanatory diagram showing a brush arrangement in the DC brush motor of FIG.
[Explanation of symbols]
1 DC brushed motor 2 Brush pair (first brush pair)
2a positive brush (first positive brush)
2b Negative electrode brush (first negative electrode brush)
3 brush pairs (second brush pair)
3a positive brush (second positive brush)
3b Negative electrode brush (second negative electrode brush)
4 Commutator 5 Armature coil 6 Rotor 7 Field magnet 8 Stator 9 Battery 11 Switch 12 Relay 51 DC brush motor 52 Positive brush 53 Negative brush 54 Negative brush 55 Commutator 56 Armature coil 57 Field magnet θ ₁ Deviation angle θ ₂ Deviation angle

Claims (4)

A DC brush motor having a stator having a field magnet and a rotor rotatably disposed in the stator and having an armature coil and a commutator connected to the armature coil,
A first brush pair including a first positive electrode brush and a first negative electrode brush slidably contacting the commutator; and a first brush pair slidably contacting the commutator and displaced by a predetermined angle from the first positive electrode brush and the second negative electrode brush. A DC brush motor having two positive brushes and a second brush pair including a second negative brush. 2. The motor according to claim 1, wherein the first brush pair is used for low-speed driving, and the second brush pair is used for high-speed driving. 3. The motor with a DC brush according to claim 1, wherein the first brush pair is arranged in a more advanced direction than the second brush pair. The motor with a DC brush according to any one of claims 1 to 3, wherein the motor is a motor used for an automobile wiper device.

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