JPH0670512A - Brush device for bi-directional rotation - Google Patents

Abstract

PURPOSE:To provide a brush device for bi-directional rotation capable of performing good commutation by obtaining good commutation without spark discharge and particularly by switching a pig tail used even when a rotor performs bi-directional rotation. CONSTITUTION:A brush main body 22 having the resistance increasing toward the rotating direction of a rotor and a first feeder 24 and a second feeder 26 connected to both the sides of the rotating direction of the rotor of the brush main body 22 are provided. And a feeder at the upstream side of the rotating direction is selectively used in response to the rotating direction of the rotor thereby suppressing a short-circuit current generated in an armature coil 14 during commutation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush device, and more particularly to an improvement of a brush device used in a DC machine.

[0002]

2. Description of the Related Art Generally, a DC motor, a DC generator or the like is constructed so that any commutator is short-circuited with a brush to perform rectification. However, due to the inductance of the armature coil or the like, the change in current during rectification is extremely delayed, and the change in current becomes large at the end of rectification, so a large reactance voltage is generated due to the inductance of the short-circuit coil. This causes a spark discharge between the brush and the commutator, roughening the commutator surface and forming an uneven surface. Therefore, the amount of wear of the brush device is increased, the life of the brush device is significantly reduced, and the vibration noise of the brush itself is increased.

In particular, in order to realize downsizing of motors and the like,
When the magnet is thinned by using a high-performance magnet, the distance between the armature and the stator yoke becomes smaller. For this reason, the magnetic resistance of the armature is reduced, the influence of the inductance of the short-circuit coil is increased, and the above-mentioned problem appears more remarkably.

[0004]

Therefore, in the past,
Various methods have been implemented for performing sparkless rectification. One of the representative ones is to shift the position of the brush to the magnetic center. However, in a motor with a large load fluctuation or a motor with a large inductance as described above, the optimum shift angle of the brush is likely to fluctuate, so stable sparkless commutation cannot be performed.

There is also a method of increasing the contact resistance between the commutator and the brush to perform resistance rectification along a good rectification curve, but since the contact resistance increases, the voltage applied to the armature drops. However, there is a problem that a decrease in motor performance, especially output torque, cannot be avoided.

In addition to this, Japanese Patent Laid-Open No. 4-4654
The proposal according to Japanese Patent No. 6 is also known. In this proposal,
The front end of the brush is made of a low resistance material and the back end is made of a high resistance material to reduce the generation of sparks.

However, even in this conventional technique, the commutation characteristics do not approach the ideal commutation curve depending on the rotor rotation position, and the current changes rapidly at the boundary between the low resistance material and the high resistance material. However, there is a problem that it is difficult to completely suppress the generation of sparks.

In addition to the above, there is a problem that the above-mentioned conventional technique can be applied only to a one-way rotating type DC motor and cannot be applied to a two-way rotating type DC motor.

The present invention has been made in view of such conventional problems, and an object thereof is to realize good rectification without spark discharge without impairing the performance of the original DC machine. Moreover, it is an object of the present invention to provide a bidirectional rotating brush device capable of performing excellent rectification even on a bidirectional rotating DC machine.

[0010]

To achieve the above object, the present invention provides a brush main body having a large resistance in the rotor rotation direction, and a first power supply line connected to both sides of the brush main body in the rotor rotation direction. And a second power supply line, and selectively uses the power supply line on the upstream side in the rotation direction according to the rotor rotation direction to suppress the short-circuit current generated in the armature coil during rectification.

[0011]

As described above, the brush device of the present invention has the first and second power supply lines respectively connected to both sides of the brush body in the rotor rotation direction, and supplies the power supply on the upstream side in the rotation direction according to the rotor rotation direction. It is configured to selectively use an electric wire.

Therefore, the brush resistance from the feeding point to the brush main body to the rotor contact surface gradually increases from the upstream side to the downstream side in the rotor rotation direction, and as a result, the short-circuit current generated in the armature coil during commutation is reduced. Can be suppressed.

In particular, according to the present invention, in the initial stage of rectification, the brush resistance between the feeding point and the commutator piece on the rectification start side becomes extremely small, and a voltage is generated in the direction of canceling the short-circuit current. become. Therefore, the short-circuit current is effectively suppressed, and good rectification without spark discharge can be performed.

Further, unlike the conventional resistance rectification, the contact resistance between the brush and the commutator piece is not made larger than the resistance of the armature winding, so that the original performance of the DC machine is not impaired and the contact resistance is good. Rectification operation can be performed.

In addition to this, according to the present invention, it is possible to perform good rectification even when the rotor portion is normally rotated and when the rotor portion is reversely rotated only by switching the power supply line to be used.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

First Embodiment FIGS. 1 to 5 show a first preferred embodiment of a rectifying mechanism provided in a so-called double lap winding type small DC motor.

As shown in FIGS. 1 and 2, in the DC motor of the embodiment, the commutator 10 provided on the rotating shaft of the rotor and the commutator 10 are provided on the stator side so as to make sliding contact with the commutator 10. And a brush device 20.

The commutator 10 comprises a plurality of commutator pieces 12-1 arranged in a ring shape along the rotor rotation direction.
12-2, 12-3, ... Including each commutator piece 12-
.. are connected by the corresponding armature coils 14 every other one. Such a winding method of the armature winding 14 is generally called double lap winding.

The brush device 20 is connected to a brush main body 22 held by a brush holder (not shown) so as to be in sliding contact with the commutator 10 with a predetermined biasing force, and both sides of the brush main body 22 in the rotational direction. And a first pigtail 24 and a second pigtail 26.

FIG. 3A schematically shows an external perspective view of the brush main body 22. This brush body 22
Is a mixture obtained by press-mixing copper and carbon while stirring and mixing them in the x direction in the figure. By doing so, the brush main body 22 has a large resistance in the pressing direction (x direction). The resistance in the Y direction orthogonal to this is relatively small. In this embodiment, the pressing direction x is formed so as to be the rotor rotation direction.

Further, the brush main body 22 has a width corresponding to two commutator pieces 12, and when the commutator 10 is rotated in the arrow direction W in the drawing, the brush body 22 is short-circuited by the armature coil 14.
The commutator pieces 12-1 and 12-3 are formed so as to perform a rectifying operation.

Incidentally, the pair of pigtails 24, 26.
The attachment depth of is from the center of the side surface of the brush main body 22 to a position not so deep.

FIG. 3B schematically shows a circuit for selectively switching the pair of pigtails 24 and 26. The pigtail switch 30 is configured to selectively connect the pigtail located on the upstream side in the rotation direction to the power supply according to the rotation direction of the rotor. Such switching may be performed manually by an operator, or may be formed so that the pigtail switching unit 30 automatically receives a signal from the rotation direction setting unit 32.

FIG. 5 (A) shows the rectifying characteristics of the brush mechanism. In the figure, 100 indicates an ideal rectifying curve, and 110
Represents the rectification curve of this embodiment.

For example, as shown in FIGS. 1 and 2, when the commutator 10 is normally driven in the direction of arrow W, the pigtail switch 30 connects the first pigtail 24 on the upstream side in the rotational direction to the power source. Then, the second pigtail 26 on the downstream side is turned off. At this time, the feeding point 24a from the pigtail 24 to the brush main body 22 and the commutator contact surface 28
The brush resistance between and increases gradually from the upstream side 22a in the rotational direction toward the downstream side 22b.

In particular, since the brush main body 22 has a larger resistance in the rotation direction x than in the y direction in FIG. 3, the brush resistance on the downstream side 22b is relatively larger than that on the upstream side 22a in the rotation direction. Become.

In FIG. 4, a feeding point 24a from the pigtail 24 to the brush main body 22 and commutator pieces 12-1, 12-.
The brush resistance between 3 and 3 is shown as Ra and Rb. FIG. 5B shows changes in the brush resistances Ra and Rb within the rectification period T. The commutator 10 is
A commutator piece 12-1 that rotates in the direction of arrow W and plunges into the commutation
When the brush starts contacting the brush main body 22, the brush main body 2
The contact area between 2 and the commutator element 12-1 gradually increases, and the brush resistance Ra gradually decreases. On the contrary, the contact area between the brush main body 22 and the commutator piece 12-3 gradually decreases, and the brush resistance Rb increases.

Here, in the present embodiment, the brush resistance from the feeding point 24a of the brush main body 22 to the commutator contact surface 28 is formed so as to gradually increase from the upstream side to the downstream side in the rotor rotation direction. . Therefore, immediately after the start of the rectification, the brush resistance Ra for the commutator piece 12-1 that enters the rectification becomes small, and the brush resistance Rb for the commutator piece 12-3 that tries to separate from the brush body 22 becomes large. Therefore, at a relatively early time point t ₁ immediately after the start of rectification, the brush resistance Ra falls below Rb, the voltage Va of the commutator piece 12-1 exceeds the voltage Vb of the commutator piece 12-3, and both commutators Piece 12-1, 1
An armature coil 14 that short-circuits 2-3 (hereinafter short-circuit coil 1
4) in the direction of canceling the short circuit current i _0.
Is energized.

Next, the operation of this embodiment will be described in comparison with the conventional brush mechanism.

FIG. 10 shows a conventional brush mechanism. In this brush device, one pigtail 26 is connected to the central position of the brush main body 22 in the rotational direction. Here, when the commutator 10 is driven in the normal direction in the direction of the arrow in the figure to start contact between the brush body 22 and the commutator piece 12-1 that plunges into the commutation, the brush body 22 moves the commutator piece 12-1. Until the contact with the entire surface of the brush body 22 is completed (until the brush main body 22 is completely separated from the commutator piece 12-3). In this rectification cycle T, when the brush body 22 short-circuits the commutator pieces 12-1 and 12-3, the short-circuit coil 14, the commutator piece 12-3, the brush body 22, and the commutator piece 12-1 are connected. A short circuit is formed by, and a short circuit current flows in the i ₀ direction due to the induced voltage of the short circuit coil 14.
At this time, the current flowing through the short-circuit coil 14 is in the i ₀ direction at the beginning of the rectification cycle, but is i by the end of the rectification.
Change in _one direction. The ideal rectification curve at this time is
It is represented by 100 in FIG. However, in the conventional brush mechanism, 110, 12 are affected by the inductance of the coil and the induced voltage generated in the short-circuit coil 14.
Insufficient rectification indicated by 0 occurs, and spark discharge occurs between the brush main body 22 and the commutator piece 12-3 at the final stage of rectification.

On the other hand, in this embodiment, the brush main body 2
2 has a large resistance in the rotation direction W, and a current is always supplied from the upstream pigtail 24 in the rotor rotation direction. Therefore, at the initial stage of commutation shown in FIG. 1, the brush resistance Ra with respect to the commutator piece 12-1 is reduced to the commutator piece 12-.
3 is lower than the brush resistance Rb for 3 and both commutator pieces 12-
A voltage is generated between 1 and 12-3 in a direction to cancel the short-circuit current i ₀ . In addition to this, since the resistance in the rotating direction of the brush main body 22 is formed to be relatively large, the short-circuit current i ₀ is suppressed also from this surface.

As described above, in this embodiment, the current flowing in the short-circuit coil 14 changes from i ₀ to i ₁ at an early stage of the initial stage of rectification.
However, since the influence of the induced voltage and the inductance described above actually exists even if the influence of the induced voltage is reduced, they are combined and, as a result, in FIG. Commutation will be initiated along a commutation curve as shown at 130.

Then, in the latter stage of rectification shown in FIG.
The commutator piece 12-1 is in sufficient contact with the high voltage region of the brush body 22, whereas the commutator piece 12-3 is only in contact with the low voltage region of the brush body 22 in a small area. . Therefore, in the short-circuit coil 14, a current substantially equal to the armature current I / 2 flowing in the short-circuit coil 14 after the rectification is finished flows in the direction i ₁ , and the rectification is finished in a state where the current change is very small. become.

Particularly, according to this embodiment, the brush resistance Ra,
Rb changes gently with the progress of rectification, and no sudden current change occurs during the entire rectification period.

Therefore, according to the present embodiment, FIG.
The rectification curve 13 close to the ideal rectification curve 100 as shown in FIG.
It is possible to perform rectification along 0, and it is possible to perform good rectification without generating sparks even in a DC motor that cannot be subjected to rectification measures such as brush shift.

In addition to this, according to the present embodiment, since the brush body 22 has a small resistance in the y direction which is orthogonal to the rotation direction, the brush body 22 as a whole has a high resistance, and compared with the case where the rectification is improved. As a result, the voltage drop in the brush main body 22 is reduced, and the original performance of the DC machine such as the decrease in output torque is not impaired.

Further, in the apparatus of the present embodiment, even when the rotor is rotationally driven in the direction opposite to the arrow W, the pigtail switching device 30 is used to supply electric power from the second pigtail 26 so that the rotor is positively moved. Good rectification can be performed as in the case of rolling.

Second Embodiment FIG. 6 shows a second preferred embodiment of the present invention.
The brush main body 22 of the embodiment has commutator piece contact surfaces 44, 46.
Are formed by integrally bonding the brush parts 40 and 42 in the shape of a right-angled triangular prism with an insulating material 48. Each of these brush parts 40 and 42 is the first
Similar to the embodiment, it is formed as a material having high resistance in the x direction,
The both are integrally bonded to each other to form a rectangular prism shape similar to that of the first embodiment.

Here, assuming that the contact portions between the brush portions 40, 42 and the commutator pieces 12-1, 12-2, 12-3 are, ... The brush device described in (1) has the effect of changing the current flowing in the short-circuit coil 14 from i ₀ to i ₁ faster than in the first embodiment.

That is, in the initial stage of the rectification, the current which tries to flow in the short circuit coil 14 in the i ₀ direction is
Similar to the embodiment, the brush portions 40 and 42 have a high resistance in the x direction, so that they are quickly damped.

In addition to this, when the commutator 10 rotates in the direction of the arrow W, the potential in the brush portion 40 gradually decreases in the order of, with respect to the pigtail 24 connected to the power source, and further, the brush portion 40. The contact resistance between the and the commutator piece becomes particularly large in the region where the contact area is small. Further, the conduction path of is → → commutator piece 12-2 →
→ becomes Here, since the contact resistance between the brush main body 22 and the commutator 10 is generated in the portion of → 12-2 →, the resistance of the conductive path of is larger than that of the first embodiment, and the area of The potential at will be lower.

Therefore, in the rectification cycle T, the action of changing the current flowing in the short-circuit coil 14 from i ₀ to i ₁ is more effective than that in the first embodiment.

Third Embodiment FIG. 7 shows a third preferred embodiment of the present invention.
In the embodiment shown in FIG. 6, a quadrangular prism is cut into two brush parts 40 and 42 so as to connect a diagonal line of a rectangle, and both brush parts 40 and 42 are adhesively fixed using an insulating material 48.

On the other hand, in this embodiment, the quadrangular prism shape is divided into two brush portions 40 and 42 each having a trapezoidal cross section, and both brush portions 40 and 42 are bonded and fixed with an insulating material 48.

By doing so, the brush portion 40
The contact area between the commutator piece 12-3 and the commutator piece 12-3 is much smaller than that in the second embodiment, and the conduction path connecting between is also →→ 12-2 →→.
Since there is a contact resistance portion of 12-2 →, the resistance also becomes large. Therefore, the brush body 22 of the embodiment
The brush resistance from the feeding point 24a to the rotor contact surface becomes higher from the upstream side to the downstream side in the rotor rotation direction than in the first and second embodiments. Therefore, the short-circuit current i ₀ flowing in the short-circuit coil 14 can be effectively suppressed. In addition, since the contact area of is smaller than that of the second embodiment, the current is changed from i _o to i
_The action of changing to the direction of ₁ is also more effective than the second embodiment.

In addition to this, in the present embodiment, the rectification is finished early in the latter half of the rectification, but the two brush portions 40 and 42 are electrically connected through the commutator 10 although the resistance is high. Therefore, the rectification cycle T does not become short.

Furthermore, in the present embodiment, as described above, the two brush portions 40 and 42 are combined to form the brush main body 22.
The resistance in the direction of rotor rotation is larger than that in the first and second embodiments. Therefore,
Even if the brush portions 40 and 42 are not formed with high resistance in the rotor rotation direction, the resistance of the brush body 22 as a whole in the rotor rotation direction increases, and good rectification can be performed.

Fourth Embodiment FIG. 8 shows a fourth preferred embodiment of the present invention.
In this embodiment, the brush main body 22 is divided into three parts in the rotor rotation direction, and three brush parts 50, 52 and 54 are integrally bonded and formed using an insulating material 56. With the above configuration, the brush parts 50, 52, 54
Since the gaps are connected to each other via the commutator pieces 12, the brush main body 22 as a whole has an extremely large resistance in the rotor rotation direction as compared with the respective embodiments.

In particular, even when each of the brush portions 50, 52 and 54 is not so large in resistance in the x direction, the brush main body 22 as a whole has very high resistance in the rotor rotation direction. It becomes large, and good rectification can be realized.

Further, in this embodiment, the central brush portion 52
Better rectification can be achieved by forming only the high resistance material.

Fifth Embodiment FIG. 9 shows a preferred fifth embodiment of this embodiment.

The brush main body 22 of the embodiment does not have a high resistance in the x direction but a high resistance in the center by setting the pressing direction at the time of molding the brush main body to x as in the first embodiment. The brush main body 22 is formed as a laminated brush using a material and a low resistance material at both ends.

Good rectification can also be realized with the above configuration.

Other Embodiments FIGS. 12 and 13 show another embodiment of the present invention. In each of the above-described embodiments, the case where the present invention is applied to a double-lap winding DC machine has been described as an example, but the present invention is not limited to this, and for example, as shown in FIGS. It can also be applied to the DC machine.
In this case, the width of the brush main body 22 in the rotor rotating direction is smaller than that of the double lap winding DC motor.
Therefore, although the rectifying effect is not equal to that of the double lap winding, an effect similar to that can be obtained.

[0056]

As described above, according to the present invention,
Without compromising the original performance of the DC machine, good rectification without spark discharge can be performed, and especially when the rotor rotates in both directions, by switching the power supply line to be used,
There is an effect that it is possible to obtain a bidirectional rotating brush device capable of performing good rectification.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a first preferred embodiment of a bidirectional rotating brush device to which the present invention is applied.

FIG. 2 is an explanatory view of the first embodiment of the brush device of the present invention.

FIG. 3A is a schematic perspective explanatory view of the brush main body of the first embodiment, and FIG. 3B is a block diagram of a pigtail switching circuit connected to the brush main body.

FIG. 4 is an equivalent circuit diagram of the brush device according to the first embodiment.

FIG. 5A is an explanatory diagram of a rectifying characteristic of the brush device according to the first embodiment, and FIG. 5B is an explanatory diagram showing how the brush resistance changes during the rectifying period.

FIG. 6 is a schematic explanatory view of a second preferred embodiment of the brush device of the present invention.

FIG. 7 is a schematic explanatory view of a third preferred embodiment of the brush device of the present invention.

FIG. 8 is a schematic explanatory view of a preferred fourth embodiment of the brush device of the present invention.

FIG. 9 is a schematic explanatory view of a fifth preferred embodiment of the brush device of the present invention.

FIG. 10 is a schematic explanatory view of a conventional brush device.

FIG. 11 is an explanatory diagram of rectification characteristics of a conventional brush device.

FIG. 12 is a schematic explanatory view of another embodiment of the present invention.

FIG. 13 is a schematic explanatory view of another embodiment of the present invention.

[Explanation of symbols]

 10 commutator 12 commutator piece 14 armature coil 20 brush device 22 brush body 24 pigtail 26 pigtail 28 commutator contact surface 30 pigtail switch 32 rotation direction setting part

Claims (2)

[Claims] 1. A rotor rotation direction comprising: a brush main body having a large resistance to a rotor rotation direction; and a first power supply line and a second power supply line respectively connected to both sides of the brush main body in the rotor rotation direction. A brush device for bidirectional rotation, characterized in that a short-circuit current generated in an armature coil during rectification is suppressed by selectively using a power supply line on the upstream side in the rotation direction according to the above. 2. The brush device for bidirectional rotation according to claim 1, further comprising a power supply line switching unit that selectively connects a power supply line on the upstream side in the rotation direction to a power source in accordance with the rotor rotation direction.