JP4659585B2 - DC motor - Google Patents

Description

  The present invention relates to a DC motor provided with an anode side and cathode side brush.

Conventionally, as a direct current motor, there is one that employs a stator having permanent magnets of 2P poles such as 4 poles and 6 poles (where P is an integer of 2 or more) in order to achieve high torque (for example, Patent Documents). 1). As such a DC motor, there is one in which the number of segments in the commutator and the number of teeth in the armature core are set to a number that is not divisible by 2P (for example, 10 for 4 poles). The direct current motor set in this way has an advantage that the pulsation of cogging torque, and hence vibration and noise are reduced compared to the case where the number of segments and the number of teeth are divisible by 2P.
JP-A-5-336719

  By the way, in the DC motor as described above, in a state where the anode side (cathode side) brush is in contact with (spanning) two segments adjacent in the circumferential direction, both ends are connected to these two segments and distributed winding is performed. The winding (coil) wound around the teeth becomes short-circuited and no current flows. In the conventional DC motor, the anode side and cathode side brushes are temporarily in contact with the two segments at the same time. That is, as shown in FIG. 6, the windings 103 are short-circuited on the anode side and cathode side brushes 101 and 102 side, respectively. Therefore, there is a problem that the total resistance value between the anode side and cathode side brushes 101 and 102 temporarily decreases, and a surge (overcurrent) S occurs as shown in FIG. This causes abnormal wear of the anode side and cathode side brushes and generation of noise and electromagnetic noise.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a DC motor capable of preventing the occurrence of a surge.

  In the first aspect of the present invention, a stator having a substantially cylindrical yoke and a 2P pole (where P is an integer of 2 or more) permanent magnet disposed on the inner peripheral surface of the yoke, and a rotating shaft A commutator in which Q segments, which are fixed and not divisible by 2P, are arranged in parallel with a gap in the circumferential direction, respectively, and an armature that is fixed to the rotating shaft and has Q teeth A core, a winding connected at both ends to the segment adjacent in the circumferential direction and wound around the teeth by distributed winding, and an anode supported by the stator and having a tip pressed against the commutator DC motor having a side brush and a cathode side brush, wherein either the anode side brush or the cathode side brush is in contact with the two segments, and the other is in contact with only one of the segments Set to be It has been.

  According to this configuration, when either one of the anode-side and cathode-side brushes is in contact with two segments, the other is in contact with only one segment. In other words, the anode side and cathode side brushes are not in contact with the two segments at the same time. Therefore, it is prevented that the anode side and cathode side brushes are simultaneously brought into contact with the two segments and the total resistance value between the anode side and cathode side brushes is reduced, and the occurrence of surge (overcurrent) is prevented. .

  According to a second aspect of the present invention, in the DC motor according to the first aspect, the arc length Wb of the tip portion of the anode side and cathode side brush is Wb ≦ ((Dc × π) / Q + Wu) / 2 (however, , Dc is set so as to satisfy the diameter of the commutator and Wu is a circumferential distance of the gap between the segments adjacent in the circumferential direction.

  According to this configuration, for example, when the anode side and cathode side brushes are alternately provided in the circumferential direction at equal angular (90 °) intervals, the configuration according to claim 1 can be easily realized. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, the direct current | flow motor which can prevent generation | occurrence | production of a surge can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the DC motor has a substantially cylindrical yoke 1 and a permanent magnet 2 having 2P poles (where P is an integer of 2 or more) fixedly disposed on the inner peripheral surface of the yoke 1. A stator 3, a rotor 4 rotatably supported inside the stator 3, and anode-side and cathode-side brushes 5 and 6 supported with respect to the stator 3 are provided. In the present embodiment, the permanent magnet 2 is provided with four poles (that is, P = 2 is set).

  The rotor 4 includes a rotating shaft 7, a commutator 9 fixed to the rotating shaft 7, and segments 8 arranged in parallel with gaps U in the circumferential direction, and also fixed to the rotating shaft 7 and extending radially. An armature core 11 having a tooth 10 and a winding 12 wound around the tooth 10 are provided.

  The number of segments 8 is Q, which is a number that cannot be divided by 2P (that is, 4 in the present embodiment), and 10 segments are provided in the present embodiment. The gap U is formed by a groove (undercut) that reaches the resin portion 13 that supports the segment 8 on the inside in the radial direction, and is formed at the same size (circumferential width) at equal angular intervals. Of course, each segment 8 is also formed in the same size (circumferential width).

  The number of teeth 10 is Q, and ten teeth are provided in the present embodiment. Both ends of the winding 12 are connected to the segments 8 adjacent to each other in the circumferential direction, and the winding 12 is wound by distributed winding over the two teeth 10. In FIG. 1, the winding 12 is schematically shown.

  The anode-side and cathode-side brushes 5 and 6 are provided two by two alternately, that is, a total of four circumferential directions at equiangular (90 °) intervals. The anode-side and cathode-side brushes 5, 6 are held by a brush holder (not shown) held with respect to the stator 3, and a tip portion that becomes a radially inner end portion by a biasing means such as a spring (not shown) is the commutator 9. Is pressed against. The anode-side and cathode-side brushes 5 and 6 are electrically connected to a power supply device (not shown), and supply drive current to the winding 12 through the commutator 9.

Here, in the present embodiment, the arc length Wb of the tip portion of the anode-side and cathode-side brushes 5 and 6 is:
Wb ≦ ((Dc × π) / Q + Wu) / 2 (where Dc is the diameter of the commutator 9 and Wu is the circumferential distance of the gap U between the adjacent segments 8 in the circumferential direction).
And a value slightly smaller than ((Dc × π) / Q + Wu) / 2 (see FIG. 2).

In other words, the angle θb about the rotation axis 7 at which the anode-side and cathode-side brushes 5 and 6 are in contact with the commutator 9 is
θb ≦ (360 ° / Q + θu) / 2 (where θu is an angle about the rotation axis 7 of the gap U between the adjacent segments 8 in the circumferential direction)
And a value slightly smaller than (360 ° / Q + θu) / 2.

  Thereby, the anode side and cathode side brushes 5 and 6 are set so that either one is in contact with two segments 8 and the other is in contact with only one segment 8. Yes. In other words, the anode-side and cathode-side brushes 5 and 6 are set so as not to be in contact with the two segments 8 at the same time.

Next, characteristic effects of the above embodiment will be described below.
(1) Since the number of segments 8 and the number of teeth 10 are set to 10 which cannot be divided by 4 for the 4-pole permanent magnet 2, the number of segments and the number of teeth can be divided by 4 Compared with (for example, 12), the pulsation of cogging torque, and hence vibration and noise are reduced.

  Moreover, the anode-side and cathode-side brushes 5 and 6 are set so that either one is in contact with the two segments 8 and the other is in contact with only one segment 8. . In other words, the anode-side and cathode-side brushes 5 and 6 are not in contact with the two segments 8 at the same time, and are in a state where the windings are short-circuited on both brush sides (see FIG. 6). There is nothing. That is, as shown in FIG. 3, the state in which the winding 12 is short-circuited only on one side of the anode side and cathode side brushes 5 and 6 (on the cathode side brush 6 side in FIG. 3) is the minimum resistance value. As shown in FIG. 4, the occurrence of surge (overcurrent) is prevented compared to the prior art (see FIG. 7). As a result, for example, abnormal wear of the anode-side and cathode-side brushes 5 and 6, noise and electromagnetic noise can be reduced.

The above embodiment may be modified as follows.
In the above embodiment, the anode-side and cathode-side brushes 5 and 6 are provided alternately two at a time, that is, a total of four at equal angular (90 °) intervals in the circumferential direction. Instead, the number of anode side and cathode side brushes may be changed, and the arrangement location (interval) may be changed.

  For example, you may change as shown in FIG. In the commutator 21 of this example, the segments 8 separated by 180 ° are short-circuited. The anode-side and cathode-side brushes 22 and 23 are provided one by one, that is, two in total, 90 degrees apart. In addition, in FIG. 5, the short-circuit member 24 which short-circuits the segments 8 is typically shown. The shapes of the anode-side and cathode-side brushes 22 and 23 (including the arc length Wb) are set similarly to the anode-side and cathode-side brushes 5 and 6 in the above embodiment. Even if it does in this way, the effect similar to the effect of the said embodiment can be acquired.

  In the above embodiment, the arc length Wb of the tip of the anode-side and cathode-side brushes 5 and 6 is set to a value slightly smaller than ((Dc × π) / Q + Wu) / 2, but Wb ≦ Any value that satisfies ((Dc × π) / Q + Wu) / 2 may be used.

  In the above embodiment, the permanent magnet 2 is provided with 4 poles, but may be changed to other numbers as long as it is 2P poles (where P is an integer of 2 or more). Further, although 10 segments 8 and 10 teeth are provided, the number may be changed to another number as long as it is not divisible by 2P (that is, the number of permanent magnets 2).

The technical idea that can be grasped from the above embodiments will be described below together with the effects thereof.
(A) In the DC motor according to claim 2, the permanent magnet is provided with 4 poles (P = 2), the segment and the teeth are provided 10 (Q = 10), and the anode side and cathode side brushes are provided. Is provided at equal angular intervals in the circumferential direction two by two alternately.

  According to this configuration, the permanent magnet is provided with 4 poles (P = 2), 10 segments and teeth (Q = 10), and the anode side and cathode side brushes are alternately provided at equal angular intervals in the circumferential direction. In the direct current motor, the configuration and the operation effect of the first aspect can be easily realized.

  (B) In the DC motor according to claim 2, the permanent magnet is provided with 4 poles (P = 2), the segments and 10 teeth (Q = 10) are provided, and the segments separated from each other by 180 ° are provided. Is a short circuit, and the anode side and cathode side brushes are provided one by one with a separation of 90 °.

  According to this configuration, the DC motor is provided with 4 permanent magnets (P = 2), 10 segments and teeth (Q = 10), and the segments separated by 180 ° are short-circuited, and the anode side In the DC motor in which the brushes on the cathode side and the cathode side brushes are provided one by one at 90 °, the configuration and the operation effect of the first aspect can be easily realized.

  (C) In the DC motor according to claim 1, the angle θb about the rotation axis at which the anode-side and cathode-side brushes contact the commutator is θb ≦ (360 ° / Q + θu) / 2 (however, , Θu is set so as to satisfy an angle around the rotation axis of the gap between the segments adjacent in the circumferential direction.

  According to this configuration, for example, when the anode side and cathode side brushes are alternately provided in the circumferential direction at equal angular (90 °) intervals, the configuration according to claim 1 can be easily realized. Can do.

The schematic block diagram of the direct-current motor in this Embodiment. The schematic diagram for demonstrating the anode side and cathode side brush in this Embodiment. The circuit diagram in case it becomes the minimum resistance value of the DC motor in this Embodiment. The motor rotation angle-current characteristic view of the DC motor in the present embodiment. The schematic block diagram of the DC motor in another example. The circuit diagram in case it becomes the minimum resistance value of the DC motor in a prior art. The motor rotation angle-current characteristic figure of the direct current motor in a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Yoke, 2 ... Permanent magnet, 3 ... Stator, 5, 6, 22, 23 ... Brush on anode side and cathode side, 7 ... Rotating shaft, 8 ... Segment, 9, 21 ... Commutator, 10 ... Teeth, 11 ... Armature core, 12 ... winding, Dc ... commutator diameter, Q ... number of segments and teeth, U ... gap, Wb ... arc length, Wu ... circumferential distance.

Claims (2)

A stator having a substantially cylindrical yoke and a permanent magnet having 2P poles (where P is an integer of 2 or more) disposed on the inner peripheral surface of the yoke;
A commutator fixed to the rotating shaft and arranged in parallel with Q segments each having a number that is not divisible by 2P with a gap in the circumferential direction;
An armature core fixed to the rotating shaft and having the Q teeth;
Winding wound around the teeth in a distributed winding with both ends connected to the segment adjacent in the circumferential direction;
A direct current motor comprising an anode side and a cathode side brush that is supported with respect to the stator and whose tip is pressed against the commutator;
The anode side brush and the cathode side brush are set so that either one is in contact with the two segments and the other is in contact with only one of the segments. DC motor. The direct current motor according to claim 1,
The arc length Wb of the tip of the anode side and cathode side brush is:
Wb ≦ ((Dc × π) / Q + Wu) / 2
(However, Dc is the diameter of the commutator, Wu is the circumferential distance of the gap between the segments adjacent in the circumferential direction)
DC motor characterized by being set to satisfy

Images