JP4827429B2 - Rotating electric machine - Google Patents

Description

  The present invention relates to a rotating electrical machine such as a motor or a generator mounted on a vehicle such as an automobile, and more particularly to a rotating electrical machine including a brush that can cope with a high voltage of an in-vehicle electrical component.

  In recent years, studies are being made to switch the power supply voltage of in-vehicle electrical components from the conventional 14V system (battery voltage: 12V) to the 42V system (battery voltage: 36V) from the viewpoint of fuel efficiency and higher output. For example, 42 V drive is also being studied for electric motors used in wiper devices, power slide doors, power windows, electric power steering devices, and the like. At that time, in the 42V drive motor, in order to increase the induced voltage generated by the winding as compared with the case of 14V drive, it is necessary to decrease the coil diameter and increase the number of turns. For this reason, in the 42V drive motor, there is a problem that sparks are likely to occur at the contact portion between the brush and the commutator, the brush life is reduced, and electromagnetic noise is increased. Further, in the 42V specification, the commutator is severely damaged, and it is difficult to select a brush that satisfies the specifications equivalent to the 14V specification.

  In particular, in the case of a multi-winding motor having more than two parallel circuits as shown in FIG. 3, when only the winding specification is 42V, the same-polarity brush (positive brush 51a, 51b or negative electrode) depends on the film formation state on the commutator. An imbalance is likely to occur in the contact state between the brushes 52a and 52b). For this reason, in combination with the variation of the windings, a circulating current is generated and the current flows through the brush. As a countermeasure against circulating current, a pressure equalization line connecting equipotential parts is conceivable. Then, it cannot cope with circulating current. Although measures such as increasing the number of amateur coils and the number of commutator segments can be taken, the number of man-hours increases and this increases costs.

  Here, in the contact portion between the brush and the commutator, a film is generated by depositing a graphite layer on the surface of the commutator under the positive brush. For this reason, the copper oxide layer formed in the lower layer of the graphite layer is in a state of being protected by the graphite layer even if the generation rate is inferior to that of the graphite layer. On the other hand, under the negative electrode brush, the removal of the oxide layer and the graphite layer is superior to the generation of the oxide layer and the graphite layer, and a film is hardly formed on the surface of the commutator. That is, the film state differs depending on the polarity on the surface of the commutator, and a film is easily formed under the positive electrode brush, and it is difficult to form a film under the negative electrode brush.

  As described above, it is difficult to form a stable film on the surface of the commutator. If the film is left as it is, the film on the surface of the commutator becomes non-uniform and current may flow intensively in a thin part of the film. When such a local current is generated, a spark is likely to be generated between the brush and commutator. In particular, in a motor having two or more homopolar brushes, an imbalance occurs in the amount of spark, and the wear deterioration of the brush is promoted. On the other hand, if the positive and negative electrode brushes are formed of a material that actively generates a film, the film formation is good and the commutator is less damaged. However, since the film becomes thick, it is difficult to control the film thickness, leading to an increase in contact voltage drop. In particular, in a motor having more than two parallel circuits, the contact voltage drop is unbalanced among the four circuits due to an increase in the coating, and the circulating current of the brush is increased and the durability is lowered.

Therefore, conventionally, various measures as shown in Patent Documents 1 to 5 have been proposed in order to make the film on the commutator uniform under both positive and negative brushes. For example, in patent document 1, the resistance value of a brush is changed along the rotation direction of a commutator, and the film | membrane is made uniform. In Patent Documents 2 to 4, a laminated brush is formed from a plurality of types of materials having different resistance values. In Patent Document 5, positive and negative electrode brushes are formed from different materials having different resistivities. The film is made uniform. By these measures, the occurrence of sparks between the brush and commutator is suppressed, the amount of brush wear is reduced, and the life of the brush is extended.
JP 61-203843 Japanese Unexamined Patent Publication No. 63-302744 Japanese Unexamined Patent Publication No. 1-202135 JP-A-5-15114 JP-A-2-106150

  However, as in Patent Documents 1 to 4, when the resistance value of the brush itself is changed or a laminated brush is formed, these brushes require a large number of manufacturing steps as compared with a single material brush. This is a factor of cost increase. In the laminated brush, the mechanical strength at the boundary between layers is weak and the durability is improved in terms of wear, but there is a problem in durability in terms of mechanical properties. Furthermore, in Patent Document 5, the resistivity of the positive and negative electrode brushes is adjusted by the contents of copper and graphite. However, the degree of film formation is not determined solely by the resistivity, and is a more effective countermeasure. Was demanded.

  It is an object of the present invention to suppress and stabilize the spark between the brush and commutator that increases with the increase in the voltage of in-vehicle electrical components, to improve the life of the brush, and to improve the durability of the rotating electrical machine. .

The rotating electrical machine according to the present invention includes a commutator fixed to a rotating shaft, positive and negative brushes that are in sliding contact with the commutator, and a multi-turn armature in which the number of parallel circuits electrically connected to the commutator is greater than two. And a positive electrode and a negative electrode brush, the positive electrode and the negative electrode brush are formed mainly of graphite, and the graphite film formed by depositing the graphite of the positive electrode and the negative electrode brush on the commutator. Is controlled by the graphite particle size of the positive electrode and the negative electrode brush, and the graphite film formed by the positive electrode brush is formed by using the positive electrode brush using graphite having a particle size larger than that of the negative electrode brush. Less than the graphite film formed by the negative electrode brush, and equalizing the film thickness of the graphite film under the positive and negative electrode brushes , Wherein the reduced circulating current generated in the armature coil by the imbalance of the contact state of the brush and the commutator between the poles brush.

  In the present invention, since a material with less graphite film formation than the negative electrode brush is used for the positive electrode brush on which the graphite film is easily formed on the commutator surface, the graphite film is evenly formed under the positive and negative electrode brushes on the commutator surface. Is done. For this reason, the occurrence of sparks between the brush and the commutator is suppressed, and the wear of the brush and the deterioration of the commutator due to the occurrence of the spark are suppressed.

In the rotating electrical machine, the amount of coating agent added to the negative electrode brush may be less than that of the positive electrode brush, and the amount of copper powder added to the negative electrode brush may be less than that of the positive electrode brush. In addition, the positive electrode brush is formed of graphite having an average particle diameter of more than 20 μm and not more than 80 μm, the negative electrode brush is formed of graphite having an average particle diameter of not more than 20 μm, and a film conditioner for the negative electrode brush The additive amount of copper powder is 0.5 wt% or less, the additive amount of copper powder is 0, the additive amount of the coating agent to the positive electrode brush is more than 0.5 wt% and 1.5 wt% or less, and the additive amount of copper powder is 35 wt% % may be the following.

On the other hand, the rotating electrical machine may be used as a 42V in-vehicle electrical component for automobiles, thereby reducing the difference in the amount of spark between the positive electrode brushes and reducing the amount of spark itself. Therefore, in a 42V motor with multiple windings with more than two parallel circuits, the circulating current due to imbalance between the same-polar brushes can be reduced, and the wear and deterioration of the brush and commutator can be suppressed, and the durability of the motor can be reduced. improves.

  According to the rotating electrical machine of the present invention, in the rotating electrical machine comprising the commutator fixed to the rotating shaft and the positive and negative brushes that are in sliding contact with the commutator, the material of the graphite film formation on the commutator is less than that of the negative brush. Since the positive electrode brush is formed, it is possible to uniformly form a graphite film under the positive and negative electrode brushes on the surface of the commutator. Therefore, the occurrence of sparks between the brush and the commutator can be suppressed, the wear of the brush and the deterioration of the commutator due to the occurrence of sparks can be suppressed, and the durability of the rotating electrical machine can be improved. In addition, since the graphite film can be equalized without the brush itself having a laminated structure, the manufacturing cost can be reduced and the mechanical strength can be improved.

  Further, according to the rotating electrical machine of the present invention, when the number of parallel circuits of the rotating electrical machine is larger than 2, the graphite film is uniformly formed under the positive and negative brushes on the surface of the commutator. Unbalance is reduced, and the circulating current generated in the armature coil can be reduced. Therefore, it is possible to suppress the circulating current from flowing through the brush, prevent the brush from being deteriorated, improve the rectification property, and reduce torque unevenness and swinging force.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a motor (rotating electrical machine) according to an embodiment of the present invention. The motor 1 is used as a driving source of a radiator fan for automobiles, and has a configuration in which an armature 3 is rotatably disposed in a bottomed cylindrical motor housing 2 as shown in FIG. Two pairs of permanent magnets 4 are fixed to the inner peripheral surface of the motor housing 2 in the circumferential direction. The permanent magnet 4 constitutes the motor 1 with 4 poles.

  The armature 3 includes an armature core 6 fixed to the rotating shaft 5 and an armature coil 7 wound around the armature core 6. The left end portion of the rotating shaft 5 in the figure is rotatably supported by a bearing 8 attached to the motor housing 2, and the armature 3 is rotatably mounted in the motor housing 2. The armature core 6 is configured by laminating a plurality of ring-shaped metal plates 9 and is fixed to the rotating shaft 5. A slot 11 is recessed along the axial direction on the outer periphery of the armature core 6. A winding 12 is wound between the slots 11. An armature coil 7 is formed on the outer periphery of the armature core 6 by the winding 12.

  A commutator (commutator) 13 is disposed adjacent to one end side of the armature core 6. The commutator 13 is externally fixed to the rotating shaft 5. A plurality of commutator pieces 14 made of a conductive material are attached to the outer peripheral surface of the commutator 13. The commutator piece 14 is made of a plate-like metal piece that is long in the axial direction, and is fixed in parallel along the circumferential direction while being insulated from each other. A riser 15 is formed at the end of each commutator piece 14 on the armature core 6 side. A winding 12 serving as a winding start end and a winding end end of the armature coil 7 is suspended around the riser 15 and fixed by fusing. Thereby, the commutator piece 14 and the armature coil 7 corresponding to this are electrically connected.

  A bracket 16 is provided at the open end of the motor housing 2, and a holder stay 17 is attached to the inside of the bracket 16. Two pairs of brush holders 18 are formed facing the holder stay 17 at four locations in the circumferential direction, and the motor 1 has a 4-parallel circuit 4-brush configuration as shown in FIG. Each brush holder 18 is internally provided with a brush 19 that can be moved up and down. The protruding tip (inner diameter side tip) of the brush 19 is in sliding contact with the commutator 13, and the brush 19 is pressed against the commutator 13 by a spring 21. A pigtail 22 is attached to the brush 19 and is electrically connected to a power source (not shown) via the pigtail 22. Electric power is supplied to the commutator 13 from an external power source via the pigtail 22 and the brush 19.

  On the other hand, in the motor 1 having such a configuration, the material of the brush 19 is made different between the positive electrode and the negative electrode in order to make the coating on the commutator 13 uniform under each brush. As described above, a film is easily formed on the surface of the commutator under the positive brush, and a film is difficult to be formed under the negative brush. Therefore, in the motor 1 according to the present invention, the brush 19 on the positive electrode side (hereinafter referred to as the positive electrode brush) has a material with little graphite film formation, specifically, a large raw material graphite particle size (for example, an average particle size of 20 μm). More than 80 [mu] m, preferably an average particle size of about 40-60 [mu] m). Further, the negative electrode side brush 19 (hereinafter referred to as negative electrode brush) is an active material for forming a graphite film, that is, the raw material graphite particle size is smaller than that of the positive electrode brush (for example, the average particle size is 20 μm or less, preferably the average particle size). A material having a particle size of about 5 to 10 μm is used.

  Thus, when a material with little graphite film formation is used for the positive electrode brush and a material with much graphite film formation is used for the negative electrode brush, the graphite film is formed evenly under the positive and negative electrode brushes, and the film formation / removal of the commutator 13 is also 2 It is performed stably between circuits. For this reason, the occurrence of sparks between the brush and commutator is suppressed, and unbalance due to the difference in contact voltage drop between the brushes of the same polarity is reduced. Therefore, the wear of the brush 19 and the deterioration of the commutator 13 due to the occurrence of sparks are suppressed, and the durability of the motor 1 is also improved. Further, the circulating current generated in the armature coil 7 is also reduced, the rectification is improved, and the torque unevenness and the swinging force are also reduced. Further, the brush 19 itself does not have a laminated structure, is easy to manufacture and advantageous in terms of cost, and mechanical strength is improved.

The amount of graphite film formation can be adjusted not only by the size of the raw graphite particle size, but also by the amount of material with grinding action and the amount of copper powder. That is, if the amount of a film adjusting agent having a grinding action (for example, a metal oxide such as SiO ₂ ) is reduced, the formed film is difficult to remove, and as a result, the film is easily formed. The amount of film modifier added to the brush is less than that of the positive brush. For example, the negative electrode brush the amount of coating modifier and less 0.5 wt%, the positive electrode brush or less 1.5 wt% exceed 0.5 wt%. Moreover, since a film | membrane will be easy to be formed when content of copper powder is decreased, the amount of copper powder addition to a negative electrode brush is made less than a positive electrode brush. For example, the negative electrode brush without added copper powder (0 wt%), the positive electrode brush added degree of copper powder below 35 wt%. In addition, you may use together adjustment of the raw material graphite particle size, and adjustment of the addition amount of a film regulator and copper powder.

  Fig. 2 shows (A) when positive and negative brush materials are used for film formation, (B) when positive and negative brush materials are used with less film formation, (C) positive electrode brush materials with less film formation, It is a table | surface which shows the experimental result in the case (material) with much film formation is used for a negative electrode brush (structure of this invention). In the experiment shown in FIG. 2, as an active material for film formation, a material graphite having an average particle diameter of 20 μm, a film conditioner of 0.2 wt% added, and copper powder not added (0 wt%) is used. did. Further, as a material with little film formation, a material graphite having an average particle diameter of 50 μm, a film conditioner added at 1.0 wt%, and copper powder at 35 wt% was used. The applied voltage is 42V in all cases, and the motor is also in the 42V specification. In this experiment, the spark state is observed with the positive electrode brush because the effect of the present invention can be confirmed more clearly by observing the spark with the brush on the side where the coating is easily formed.

  As can be seen from the table in FIG. 2, the brush wear rate is clearly smaller in (C) than in (A) and (B). Further, the wear rate of the commutator (the wear rate at the normal sliding portion at the central portion in the circumferential direction of the commutator) is large because (B) has little film formation, and (A) and (C) are almost the same. On the other hand, in (A) and (B), there is a difference in the amount of spark between the two positive brushes, and both are in an unbalanced state. In particular, in the case of (B), the difference in the amount of sparks is large and the imbalance is remarkable, and the amount of sparks generated is also large. On the other hand, in (C), the difference in spark amount between the two positive brushes is small, the balance is good, and the spark amount itself is small.

  As described above, when a material with little film formation is used for the positive electrode brush and a material with much film formation is used for the negative electrode brush, the amount of sparks between the positive electrode brushes can be clearly understood from the result of (C) even if the motor 1 is 42V specification. Difference can be kept small, and the amount of sparks is small. Therefore, by adopting the configuration (C) according to the present invention, it is possible to reduce the circulating current due to imbalance between the same-polarity brushes in a motor of 42V specification, particularly a multi-winding motor having more than two parallel circuits. The wear and deterioration of the brush and commutator are suppressed, and the durability of the motor is improved.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, an example in which the motor of the present invention is used as a drive source for a radiator fan is shown. However, the application is not limited to this, and a power slide door, a power window, a wiper device, and an electric power steering are used. It can also be used as a drive source for in-vehicle electrical products such as motors and motors used in other electrical products. Further, the raw material graphite particle size and the coating agent / copper powder addition ratio shown in the above-described examples are merely examples, and the present invention is not limited to only those values.

It is sectional drawing which shows the structure of the motor which is one Example of this invention. It is a table | surface which shows the experimental result of the structure by this invention, and its comparative example. It is explanatory drawing which shows the winding circuit structure of the double winding motor with two or more parallel circuits.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Motor housing 3 Armature 4 Permanent magnet 5 Rotating shaft 6 Armature core 7 Armature coil 8 Bearing 9 Metal plate 11 Slot 12 Winding 13 Commutator 14 Commutator piece 15 Riser 16 Bracket 17 Holder stay 18 Brush holder 19 Brush 21 Spring 22 Pigtail 51a , 51b Positive electrode brush 52a, 52b Negative electrode brush

Claims (4)

A rotating electrical machine comprising: a commutator fixed to a rotating shaft; positive and negative brushes in sliding contact with the commutator; and a multi-turn armature coil having more than two parallel circuits electrically connected to the commutator. Because
The positive electrode and the negative electrode brush are formed mainly of graphite,
The graphite film of the positive electrode and the negative electrode brush is controlled by the graphite particle size of the positive electrode and the negative electrode brush.
By forming the positive electrode brush using graphite having a larger particle diameter than the negative electrode brush, the graphite film formed by the positive electrode brush is less than the graphite film formed by the negative electrode brush, The film thickness of the graphite film under the positive and negative electrode brushes is equalized, and the circulating current generated in the armature coil due to the imbalance of the contact state between the brush and the commutator between homopolar brushes is reduced. Rotating electric machine.   2. The rotating electrical machine according to claim 1, wherein a coating agent addition amount to the negative electrode brush is smaller than that of the positive electrode brush, and a copper powder addition amount to the negative electrode brush is smaller than that of the positive electrode brush. Rotating electric machine. 3. The rotating electrical machine according to claim 1, wherein the positive electrode brush is formed of graphite having an average particle diameter of more than 20 μm and not more than 80 μm, and the negative electrode brush is formed of graphite having an average particle diameter of not more than 20 μm. As
The negative electrode brush has an addition amount of a film modifier of 0.5 wt% or less and an addition amount of copper powder of 0,
The positive electrode brush is a rotating electrical machine characterized in that the amount of coating agent added is more than 0.5 wt% and not more than 1.5 wt%, and the amount of copper powder added is not more than 35 wt%. The rotating electrical machine according to any one of claims 1 to 3, wherein the rotating electrical machine is used as a 42V in-vehicle electrical component for an automobile.

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