JPH09201016A - Brush holding device for rotating electric machine - Google Patents

Abstract

(57) [PROBLEMS] To hold a brush for a rotating electric machine configured such that the brush does not come into contact with the metal cage of the brush holder and the brush does not wear abnormally even if the brush is inclined in the rotation direction or the axial direction. Provide equipment. A first insulating plate (6) is provided on the head of the brush (2) and a second insulating layer is provided on the lower part of the cage (10) so that the conductive layer (4) of the brush (2) and the inside of the cage (10) do not contact each other. Board 1
1 and a first insulating plate 6 provided on the head of the brush 2.
Moves toward the lower part of the cage box 10 as the brush 2 wears, and when the brush 2 reaches the wear limit, the first insulating plate 6 moves to the second insulating plate 11 attached to the lower part of the cage box 10. The brushes 2 are configured to come into contact with each other, and the brush 2 is locked by the contact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush holder for a rotary electric machine applied to a rotary electric machine, and more particularly to a brush holder for a rotary electric machine applied to an AC commutator motor such as an electric power tool and a vacuum cleaner. Is.

[0002]

2. Description of the Related Art In response to recent energy saving, AC commutator motors used in electric tools and vacuum cleaners are required to have high efficiency and high output. AC commutator motors generally do not have commutating poles to control the commutation action, and thus commutation is poor. So, the brushes of these electric motors
Graphite is used as the main raw material, and resinous brushes and graphite-carbonaceous brushes that use resin as the binder are used, and most of them have a high specific resistance of 10,000 μΩ-cm or more for resistance rectification.

Therefore, when the current supplied to the electric motor passes through this brush, the voltage drop generated becomes large, and the electric loss of the brush becomes large, which is one of the causes of the low motor efficiency.

As a solution to this, Japanese Patent Laid-Open No. 62-1714
As described in Japanese Patent Laid-Open No. 34-34, there has been proposed a brush configuration that reduces the resistance loss of the brush body. The feature is that a low resistance conductive layer is formed by applying a paint such as copper or silver to the surface of the high resistance brush body (the surface excluding the rubbing surface) and drying it. The voltage drop between the brush and the brush body is 25% or less of the voltage drop at the contact portion between the brush and the commutator. Therefore,
The voltage drop of the brush is naturally small and the electric loss of the motor is reduced, so that the efficiency of the motor is improved.

However, in this type of brush, an electric current flows from the metal cap portion of the brush head and the lead wire, and moreover, the brush is inclined in the rotating direction and the axial direction, so that the conductive layer (copper, silver, paint) is formed. ) And the cage contact each other, and a current flows through the contact portion. As a result, the contact part may be damaged by electric contact or the like, or may stiffen firmly and hinder the good contact of the brush to generate a spark, resulting in abnormal wear or inability of the electric motor to rotate. To prevent these problems, a gap is provided between the brush cap metal part and the cage metal part so that the metal part of the cage does not come into contact with each other so that no current flows. However, contact is not completely prevented. .

Further, as described in Japanese Patent Application Laid-Open No. 5-182733, a specific method for providing a low resistance layer around the brush has been proposed. The feature is that the entire surface of the brush base material (excluding the ground surface) is coated with an electrically conductive metal by electroless plating, which reduces the electric resistance (voltage drop) of the brush as a whole. Kai 62-1
Like the one described in Japanese Patent No. 71434, the electric loss is reduced to improve the motor efficiency.

In this case, since all the surfaces other than the ground surface of the brush are low resistance layers, electric contact, stickiness and the like are more likely to occur than the brush. Therefore, abnormal wear occurs in a short time, and countermeasures against it are desired, but at present, contact measures cannot be completely prevented because the same countermeasure method as described above is used.

[0008]

As described above, the metal cap portion of the brush head and the metal portion of the cage are in contact with each other, and a current is shunted between the cage side and the brush body (current flowing in the brush body, holding When the bottleneck current flows through the metal part of the container, the contact part between the conductive layer (copper, silver, paint) provided on the brush surface and the retainer is damaged (electrolytic contact), causing the brush to stick firmly and causing abnormal wear of the brush. The electric motor may not be able to rotate due to improper energization. As a countermeasure against this, a current is supplied to the cage by changing the current path by providing a clearance between the metal part of the brush head and the metal part of the cage to prevent them from contacting each other.
Has been reduced.

However, even in the above technique, when the brush is inclined in the rotation direction or the axial direction, the conductive layer (copper, silver,
The paint) and the holder come into contact with each other, and an electric current flows through the contact portion. As a result, the contact portion is damaged due to electric contact or the like and becomes astringent, and similarly to the above, there are adverse effects such as abnormal wear of the brush and inability to rotate the electric motor due to improper energization.

It is an object of the present invention to prevent the brush from contacting a metallic retainer of a brush retainer even if the brush is inclined in the rotational direction or the axial direction, and prevent the brush from being abnormally worn. To provide a device.

[0011]

In order to achieve the above object, the present invention provides a brush having a conductive layer on the surface except a sliding surface with a commutator, a cage for holding the brush, and A brush holding device for a rotating electric machine, which is arranged in a holder box and has a pressing spring that presses the brush to bring the sliding surface of the brush into contact with a ground surface of the commutator, wherein the conductive layer of the brush and the conductive layer are provided. A first insulating plate is provided on the head of the brush, and a second insulating plate is provided on the lower portion of the cage so as not to contact the inside of the cage.

Another feature of the present invention is that a brush having a conductive layer on a surface except a sliding surface with a commutator, a cage for holding the brush, and a cage arranged in the cage. In a brush holding device for a rotating electric machine having a pressure spring that presses a brush to bring the sliding surface of the brush into contact with the sliding surface of the commutator, the conductive layer of the brush and the inside of the cage are in contact with each other. The first insulating plate is provided on the head of the brush so that the first insulating plate is provided on the head of the brush and the second insulating plate is provided on the lower part of the cage.
Of the insulating plate moves toward the lower part of the cage as the brush wears, and when the brush reaches the wear limit, the first insulating plate is attached to the lower part of the cage to generate the second insulating plate. The brush is configured to come into contact with the plate, and the brush is locked by the contact.

According to the present invention, the first insulating plate is provided on the brush head and the second insulating plate is provided on the lower part of the cage. Further, the first insulating plate provided on the head of the brush moves toward the lower part of the cage as the brush wears, and when the brush reaches the wear limit, the first insulating plate moves to the lower part of the cage. The brush is locked by contacting the second insulating plate mounted on the.

Thus, even if the brush is tilted due to a rotational force or the like, it is possible to prevent the brush from contacting the metal portion of the cage, and prevent a bottleneck current from flowing to the brush. Further, when the brush reaches the wear limit, the first insulating plate on the brush head comes into contact with the second insulating plate on the lower portion of the cage to serve as a stopper, and the abrasion of the brush can be stopped. As a result, since the lead wire and the metal fitting do not come into contact with the commutator, damage to the lead wire and the metal fitting can be prevented. Further, by using a material having a vibration absorbing property for the insulating plate, it is possible to suppress the vibration of the brush, improve the frictional characteristics, and prevent electric contact, stickiness and abnormal wear of the brush.

That is, it is possible to improve the brush life while maintaining high efficiency and stable rectification performance from the beginning of operation of the rotating electric machine.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A brush holding device for a rotary electric machine and a brush for a rotary electric machine according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a brush holding device for a rotary electric machine according to an embodiment of the present invention. In the brush holding device for a rotating electric machine, a conductive layer (for example, copper, silver, conductive paint, etc.) is formed on the surface of the brush main body 3 excluding the sliding surface with the commutator 1.
4, a lead wire 5 for energizing the brush 2 and the metal cap 9, a first insulating plate 6 provided on the brush head, and a brush for pressing the brush 2 from above the insulating plate 6. A brush composed of a pressure spring 7 for bringing the sliding surface (rubbing surface) of 2 into contact with the rubbing surface of the commutator 1, a metal cap 9 to which the lead wire 5 of the brush 2 is connected, and a metallic cage box 10. The holder 8 and the second insulating plate 11 provided below the holder box 10 of the brush holder 8 are included.

The first insulating plate 6 and the second insulating plate 11 are
It is formed of a material having both insulating properties and elasticity, and for example, rubber, Teflon, Bakelite, etc. are good materials. In addition, since it is a material that has both insulating properties and elasticity, it can absorb brush vibration in the rotating direction and vibration from the commutator side, improve the brush rubbing characteristics, and have a good effect on abnormal brush wear and rectification performance. give.

Here, the first insulating plate 6 of the brush head is
As shown in FIGS. 2 and 3, the shape thereof is similar to that of the brush head, and the hole 12 through which the lead wire 5 is inserted in the central portion and the first insulating plate on the brush head. A recess 13 having substantially the same size and shape as that of the brush head is provided so that 6 can be mounted. By fitting the recess 13 in the brush head, the first insulating plate 6 can be fixed to the brush head and no positional deviation occurs, so that good squeezing characteristics can be maintained.

The width a and the thickness b of the first insulating plate 6 are larger than the width and thickness of the outer dimension of the brush 2, and are smaller than the width and thickness of the inner dimension of the cage 10. Determine the dimensions that do not hinder the sliding of the brush.

For example, as shown in FIG. 6A, when the brush 2 has a width of 10 mm, a thickness of 7 mm (not shown), and a length of 20 mm, the dimension of the first insulating plate 6 is determined. An example will be described below.

The actual processed size of the brush 2 is 9.7 in width.
mm, thickness 6.8 mm, the thickness t of the first insulating plate 6
Is 0.3 mm, the width of the first insulating plate 6 is 10.3 mm.
And the thickness is 7.4 mm. The gap between the inside of the cage 10 and the first insulating plate 6 is 0.15 mm wide and 0.1 mm thick.
When it is set to 1 mm, the inner width of the cage 10 is 10.45 m.
m, and the thickness is 7.5 mm, which is the same as when the conventional brush 2 alone is inserted into the cage 10.

That is, since the outer dimension of the first insulating plate 6 is larger than the outer dimension of the brush 2 by 0.3 mm in width and thickness, the conductive layer 4 contacts the metal part of the cage 10 even if the brush is inclined. do not do. In addition, the length C of the first insulating plate 6 in FIG.
Is determined by how much the brush wear limit described below is set.

Second attached to the lower part of the cage box 10
As shown in FIGS. 4 and 5, the insulating plate 11 of FIG.
A groove 14 is provided on the upper surface of the second insulating plate 11 so that it can be inserted into the end portion of 0. By inserting the groove 14 into the end portion of the cage 10, the second insulating plate 11 can be fixed to the cage 10 and positioned.

The inner widths d and e are determined according to the dimensions of the first insulating plate 6 with a nominal gap corresponding to the inner dimension of the conventional cage 10 and the outer dimension of the brush.

The length f is determined with the length C of the first insulating plate 6 of the brush head depending on how many mm the wear limit h'of the brush shown in FIG. 6 (b) is set.

For example, as shown in FIG. 6 (a), the length of the brush is 20 mm, and the size which allows the brush to wear is 12
mm, when the bad dimension due to wear is set to 8 mm (wear limit), the depth g of the first insulating plate 6 at the brush head is 3 mm, and the mounting position of the second insulating plate 11 at the bottom of the cage 10 When the distance j from the surface of the commutator 1 is 5 mm, g (3 mm)
+ J (5 mm) = h '(8 mm), and as shown in Fig. 6 (b), the size is the same as the wear limit of the brush of 8 mm, so that the brush can be locked to prevent abnormal wear.

The structure of the brush holding device for a rotary electric machine described above is standard, but the following structure is proposed for a small machine or a low-priced product that has a small current capacity and mechanical vibration.

As shown in FIG. 7, the third insulating plate 6'is
The shape of the first insulating plate 6 of the brush head is simplified and formed into a single plate. Hole for lead wire 12
2 is the same as that in FIG. 2, but the concave portion for inserting into the brush provided in FIG. 2 is omitted to form a flat plate. If you do this, brush 2
Since the third insulating plate 6'and the third insulating plate 6'cannot be fixed to each other, they can be fixed to each other by adhering them with an adhesive, and the same effect as in the case of FIG. 2 can be obtained.

The fourth insulating plate 11 'attached to the lower part of the cage 10 has a cage 1 as shown in FIG.
Only the portions corresponding to the two end portions of 0 are U-shaped, and the width of the groove of the insulating plate is the same as or slightly narrower than the plate thickness of the retainer box 10 and inserted and fixed. The fixing method is possible by press-fitting with a small tolerance of the adhesive or the inner groove, which enables positioning and facilitates mounting. Fourth insulating plate 11 '
The shape and dimension of is determined by the same method as described above.

The first insulating plate 6 of FIG. 2 and the fourth insulating plate of FIG.
Insulating plate 11 ', third insulating plate 6'of FIG. 7 and second insulating plate of FIG.
Even if the combination with the insulating plate 11 is arbitrarily performed, the same effect as the above-described effect can be obtained.

In order to confirm the effect of this embodiment, as shown in FIG. 9, the first insulating plate 6 and the second insulating plate 11 are not provided, and as shown in FIG. 6, in the case where the second insulating plate 11 was provided, the occurrence of electric contact on the side surface of the brush and the life characteristics of the brush were measured.

As a result, when the insulating plate is not provided, when the electric motor is rotated, the brush 2 is inclined and the conductive layer 4 of the brush comes into contact with the cage 10 as shown in FIG. The electricity is supplied from the cage box 10 of (a), (b), (c), and (d) to (e). Here, the portions B and E are places where the conductive portion 4 of the brush and the cage box 10 contact.

Here, the fluctuation value of the voltage drop between the brush and the commutator, which shows the brush abrasion state (a large value indicates that the brush abrasion state is bad), and a brush life test of 1 kW
A class AC commutator motor was used. The results are shown in FIGS. 11 and 12.

As shown in FIG. 11, in the case of the conventional method (without an insulating plate), the fluctuation value of the voltage drop becomes large after about 100 hours of operation, and as shown in FIG. The electric motor stopped for 200 hours. When the side surface of the brush at this time was observed, electric contact was generated at the contact portion as shown in FIGS. That is, the convex portion on the surface of the brush adhered to the inside of the mating cage box 10, hindered good sliding, generated sparks, wasted, and stopped the electric motor.

Then, the life test of the brush was similarly conducted by using the apparatus equipped with the insulating plate according to the present embodiment. FIG.
As shown in the results in FIGS. 1 and 12, the brush life according to the present embodiment is only the voltage drop fluctuation due to the deterioration of the condition of the commutator and the like with the passage of time, and the brush life is not deteriorated. When the side surface of the brush after the test was observed, there was no damaged portion as shown in FIGS. 10C and 10D, and the slidability in the cage 10 did not change from the initial stage.

Another reason why the brush life is long is that the materials of the insulating plate 6 on the brush head and the insulating plate 11 on the lower part of the cage box 10 absorb the vibration of the brush 2 so that the sliding characteristics are remarkably improved. it is conceivable that.

Another major effect of this embodiment is that in the conventional method, when the brush 2 is abnormally worn, it is worn beyond the brush wear limit, so that the lead wire 5 or the like slides directly on the commutator 1 and step wear or the like occurs. It causes a short circuit accident and burns out. Therefore, in the present embodiment, as described above, by using the first insulating plate 6 and the second insulating plate 11 having proper lengths, as shown in FIG.
As shown in FIG. 5, brush abrasion can be stopped, and abnormal wear of the brush 2 and burnout of the electric motor can be prevented.

[0039]

According to the present invention, it is possible to suppress the bottleneck current flowing to the brush and the brush holding device and prevent electrolytic corrosion of the brush surface and abnormal wear of the brush, so that the life of the brush can be improved. Therefore, the reliability of the rotary electric machine can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a brush holding device for a rotary electric machine according to an embodiment of the present invention.

2 is a configuration diagram of an insulating plate of a brush head of the brush holding device for a rotary electric machine of FIG. 1. FIG.

3 is a cross-sectional view taken along line XX of the insulating plate of FIG.

FIG. 4 is a configuration diagram of an insulating plate attached to a lower portion of a brush holding box of the brush holding device for a rotary electric machine of FIG.

5 is a cross-sectional view taken along line YY of the insulating plate of FIG.

FIG. 6 is an explanatory diagram of a dimensional configuration of the brush holding device for a rotary electric machine of FIG. 1.

FIG. 7 is a configuration diagram of an insulating plate of a brush head, showing another embodiment.

FIG. 8 is a configuration diagram of an insulating plate under the cage box 10, showing another embodiment.

FIG. 9 is a view showing an electric contact state of a conventional rotating machine brush.

FIG. 10 is a view showing an electric contact state of a brush for a rotating electric machine according to the method of the present invention.

FIG. 11 is a diagram showing the results of a variation test of brush voltage drop according to the conventional method and the method of the present invention.

FIG. 12 is a diagram showing the results of a brush life test according to the conventional method and the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Commutator, 2 ... Brush, 3 ... Brush body, 4 ... Conductive layer, 5 ... Lead wire, 6 ... 1st insulating plate, 6 '... 3rd insulating plate, 11 ... 2nd insulating plate , 11 '... Fourth insulating plate, 7
... Pressure spring, 8 ... Brush holder, 9 ... Metal cap, 1
0 ... Retainer box, 12 ... Lead wire passage hole, 13 ... Recessed portion, 1
4 ... groove

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mika Takahashi 7-2-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Co., Ltd. 3-3-1, Machi Yamazaki Factory, Hitachi Chemical Co., Ltd.

Claims (9)

[Claims] 1. A brush having a conductive layer on a surface other than a sliding surface with a commutator, a cage for holding the brush, a cage arranged in the cage for pressing the brush, and In a brush holding device for a rotating electric machine having a pressure spring for bringing a sliding surface into contact with the ground surface of the commutator, the head of the brush is provided so that the conductive layer of the brush and the inside of the cage are not in contact with each other. A brush holding device for a rotating electric machine, wherein a first insulating plate is provided in a portion and a second insulating plate is provided in a lower portion of the cage box. 2. The brush according to claim 1, wherein the first insulating plate provided on the head of the brush moves toward the lower part of the cage as the brush wears, and the brush reaches the wear limit. Then, the first insulating plate comes into contact with the second insulating plate provided at the lower portion of the cage, and the brush is locked by the contact. Brush holding device for electric machines. 3. The first insulating plate according to claim 1 or 2, wherein the first insulating plate has a plate shape having a thickness, a width and a length, and the dimensions of the thickness and the width are the same as those of the brush. A brush holding device for a rotary electric machine, having a size larger than a size and smaller than a thickness and a width inside the brush holder box. 4. The first insulating plate according to claim 1, wherein the first insulating plate has a recess on the lower surface of the first insulating plate so that the first insulating plate can be mounted on the head of the brush. A brush holding device for a rotating electric machine, characterized by being provided. 5. The second insulating plate according to claim 1 or 2, wherein the second insulating plate is a rectangular cylinder having a thickness, a width and a length,
The rotating electrical machine is characterized in that the inner thickness and width of the second insulating plate are larger than the thickness and width of the brush and smaller than the inner thickness and width of the cage. Brush holding device. 6. The second insulating plate according to claim 1, 2 or 5, wherein the second insulating plate is attached to the lower part of the cage. A brush holding device for a rotating electric machine, characterized in that it has a groove on its upper surface. 7. The brush according to claim 1, wherein the length of the first insulating plate and the length of the second insulating plate are within the wear limit of the brush. A brush holding device for a rotary electric machine, characterized in that the size is set so that it can be locked. 8. The brush holding device for a rotating electric machine according to claim 1, wherein the first insulating plate and the second insulating plate are made of a material having both insulating properties and elasticity. . 9. A brush having a conductive layer on a surface other than a sliding surface with respect to a commutator, a cage for holding the brush, and a brush arranged in the cage to press the brush to push the brush. In a brush holding device for a rotating electric machine having a pressure spring for bringing a sliding surface into contact with the ground surface of the commutator, the head of the brush is provided so that the conductive layer of the brush and the inside of the cage are not in contact with each other. Part is provided with a first insulating plate and a lower part of the cage is provided with a second insulating plate, and the first insulating plate provided on the head of the brush is attached to the cage as the brush wears. Move towards the bottom of
When the brush reaches the wear limit, the first insulating plate comes into contact with the second insulating plate mounted on the lower portion of the cage,
A brush holding device for a rotating electric machine, characterized in that the brush is locked by the contact.