JP2003189548A - Dc motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC motor in which the lifetime of a brush is prolonged. <P>SOLUTION: The DC motor comprises an armature constituting a commutator by arranging a plurality of commutator segments radially on the outer circumference of a shaft while insulating from each other, a plurality of brushes formed by stacking high copper content materials 31, 32 and 33 and low copper amount materials 34 and 35 alternately in the radial direction from the inner diameter side and connecting the high copper content material 33 located on the outermost diameter side with a pigtail 30, and means for bringing each brush 3 into contact with the commutator segment with a specified pressure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush type DC electric motor in which a brush is arranged in a pressed state on a commutator of an armature to perform commutation between the brush and the commutator.

[0002]

2. Description of the Related Art In a direct current motor used as a starter for starting an engine, a metal graphite brush having a copper content of 60% by weight or more is generally adopted in order to secure a large current carrying capacity and improve output. .

[0003]

The metal graphite brush is
Since the specific resistance is small, there is little heat generation during high-power operation due to high-current energization. However, when a metal-graphite brush, which is disadvantageous in resistance rectification, is used, a large number of rectification sparks are generated on the contact surface with the commutator, and wear occurs at a high speed. The wear rate increases with the rough damage of the commutator. Therefore, when used at a high output, the service life of the DC motor using high carbon brushes used in industrial vehicles is shorter than the actual operation time (cumulative operation is about 30 hours).

An object of the present invention is to provide a DC electric motor having a brush having a long life.

[0005]

[Means for Solving the Problems] (Claim 1) An armature has a commutator in which a plurality of commutator pieces are radially arranged on the outer circumference of a rotary shaft.

In each brush, a high copper content material and a low copper content material are alternately laminated in the radial direction from the inner diameter side, and a pigtail is connected to the high copper content material located on the outermost diameter side. The brush pressure contact means brings each brush into contact with the commutator piece at a predetermined pressure.

At the initial stage of operation, the high copper content material comes into contact with the commutator piece, so that the high copper content material is worn away and the commutator piece is also roughened. While the high copper content material is in contact with the commutator element, the specific resistance of the brush is small, and the amount of heat generated is small even when high-power operation is performed with a large current. When the first high copper content part has worn out and the low copper content part comes into contact with the commutator piece,
Since the brush specific resistance increases, resistance rectification is performed.

In the operation stage in which the low copper content material portion contacts the commutator piece, the brush wear rate and the rough damage rate of the commutator piece decrease, and a lubricating film is formed on the surface of the commutator piece. As a result, the brush wear rate can be reduced in the operation stage in which the high copper content material then contacts the commutator piece. With the above-described operation, the DC motor can have a long brush life. In addition, in the operation stage in which the high copper content material portion comes into contact with the commutator piece, a high output is obtained by energizing a large current.

(Regarding Claim 2) The brush resistivity is reduced by using a metal-graphite high copper content material having a copper content of 55% by weight or more, and the high copper content material comes into contact with the commutator piece at an operating time. In, the amount of heat generated during high-power operation by energizing a large current is reduced.

During the operation period when the low copper content material portion contacts the commutator piece, the brush wear rate and the roughening speed of the commutator piece can be sufficiently reduced, and the formation of a lubricating film on the surface of the commutator piece can be achieved. As can be done, a high carbonaceous low copper content material with a copper content of less than 55 wt% is used to increase the brush resistivity.

(Regarding Claim 3) Since the lubricating film may be formed on the surface of the commutator piece at the operating time when the low copper content material portion contacts the commutator piece, the volume occupied by each low copper content material The ratio is made smaller than the volume ratio occupied by the high copper content material adjacent to the outer diameter side of the low copper content material.

(Claim 4) The copper content of the high copper content material located on the outer diameter side of the brush (excluding the high copper content material located on the outermost diameter side) is set to the copper content ratio on the inner diameter side of the brush. It is smaller than the copper content of the copper content material. As a result, the brush wear speed and the roughening speed of the commutator piece are reduced, and the life of the brush can be further extended.

(Claim 5) The volume ratio of the high copper content material located on the outer diameter side of the brush is set larger than that of the high copper content material located on the inner diameter side of the brush. As a result, the operating period in which the brush wear speed and the roughening speed of the commutator piece decrease decreases, so that the life of the brush can be further extended.

(Claim 6) A high copper content material having a copper content ratio higher than that of each of the high copper content materials is arranged at a portion which comes into contact with the commutator element in an initial stage of operation. As a result, the brush fits into the commutator piece at an early stage, and sliding noise due to contact between the commutator piece and the brush can be reduced from the initial stage of operation.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention (claims 1 to 1)
DC motor A according to (corresponding to 3) will be described based on FIGS. 1 to 4. The DC motor A is a starter DC motor for starting an engine, and includes an armature 2 having a commutator 1,
The brush 3, the brush pressing means 4, the yoke 5, the permanent magnet 6 and the like are provided.

The commutator 1 is composed of commutator pieces 12 and insulating portions 13 which are alternately arranged in a cylindrical shape on the outer circumference of a shaft 11. Each commutator piece 12 is connected to an armature coil, and the insulating portion 13 is formed so that its surface is retracted inward from the surface of the commutator piece 12.

The armature 2 includes inner and outer armature cores, armature coils wound around these armature cores, and the commutator 1.
Etc. A pipe having a pair of bearings fitted therein is press-fitted and fixed in the hollow portion of the inner armature core, and is rotatably supported by the shaft 11 via the bearings.

The brushes 3 (for positive poles and for negative poles) have a substantially square pole shape, are connected to a pigtail 30 for energization, and are in sliding contact with the rotating commutator piece 12 on the inner diameter side.

This brush 3 comprises high copper content materials 31, 32, 3
3 and low copper content materials 34 and 35 are alternately (described later) laminated in the radial direction (see FIG. 4). -In order from the commutator piece 12 side, the order of the high copper content material 31-the low copper content material 34-the high copper content material 32-the low copper content material 35-the high copper content material 33. Further, the contact surface of the high copper content material 31 that comes into contact with each commutator piece 12 is a curved surface corresponding to the curved surface of the commutator piece 12.

The high copper content materials 31, 32 and 33 are metallic graphite materials having a high copper content (70% by weight in this embodiment). The low copper content materials 34 and 35 are high carbonaceous materials having a low copper content (45% by weight in this embodiment). Further, in this embodiment, the ratio of the volume occupied by each low copper content material (low copper content materials 34, 35) and the volume occupied by each high copper content material (high copper content materials 31, 32) is 1: I have set it to 2.

The pigtail 30 is a coated copper wire, and is connected (caulked, copper powder, mold, etc.) to the side surface of the high copper content material 33 of the brush 3. Each pigtail 30 is electrically connected to a terminal, and a battery voltage is applied when the engine is started.

The brush pressing means 4 comprises a brush holder 41 for accommodating the brush 3 and a brush spring 42 for bringing the brush 3 into contact with the commutator piece 12 at a predetermined pressure (FIG. 3).
reference). The brush holder 41 made of insulating plastic has a notch for exposing the pigtail 30, and accommodates the brush 3 in a displaceable manner.

The brush spring 42 (coil spring) is
The base end faces the back of the brush holder, and the tip is the brush holder 4
The brush 3 (high copper content material 33) is pressed in the inside 1. The brush spring 42 may be the spiral spring 420 shown in FIG.

The DC motor A of this embodiment operates as follows and has the following advantages. In the initial stage of operation of the DC motor A, the metal-graphite high copper content material 31 having a copper content of 70% by weight comes into contact with the commutator piece 12, and during this time, the brush specific resistance is small, and a high current is applied to produce a high output. The amount of heat generated is small even during operation. The first high copper content material 31 is worn and finished (the commutator piece 12 is also rough), and the low copper content material 34 portion is commutator piece 1.
When it comes into contact with 2, the brush specific resistance increases, so that resistance rectification is performed.

During the operation stage in which the high carbon low copper content material 34 having a copper content of 45% by weight contacts the commutator element 12, the brush wear rate and the roughening rate of the commutator element 12 are sufficiently reduced. A lubricating film is formed on the surface of the commutator piece 12. As a result, next, the brush wear rate can be reduced in the operation stage in which the high copper content material 32 contacts the commutator piece 12.

By the above-mentioned operation, the DC motor A of this embodiment can secure a high output by energizing a large current and can achieve a long life of the brush (about 40 hours or more in cumulative operation). In addition, the operating time when the low copper content materials 34 and 35 come into contact with the commutator element 12 may be such that a lubricating film is formed on the surface of the commutator element 12, so that the volume ratio occupied by the low copper content materials 34 and 35. Is smaller than the volume ratio occupied by the high copper content materials 31 and 32.

Next, a DC motor B according to a second embodiment of the present invention (corresponding to claims 1, 2, 3 and 6) will be described with reference to FIGS. 1 to 3 and 5. The brush 3 (for positive electrode, for negative electrode) is made by alternately stacking high copper content materials 37, 38, 39 and low copper content materials 34, 35 in the radial direction, and at the same time, high copper content material 37. , 38, 39 having a copper content of 80% by weight, which is higher than the copper content of 38, 39, is laminated (described in detail below) at a portion in contact with the commutator piece 12 in the initial stage of operation. .

High copper content material 36 in order from the commutator piece 12 side
-High copper content 37-Low copper content 34-High copper content 38-Low copper content 35-High copper content 39 in this order. Further, the contact surface of the high copper content material 36, which is in contact with each commutator piece 12, is made flat.

The high copper content materials 37, 38 and 39 are metallic graphite materials having a copper content of 60% by weight. Low copper content materials 34, 35
Is a high carbonaceous material having a copper content of 45% by weight.

In this embodiment, the ratio of the volume occupied by each low copper content material (low copper content material 34, 35) to the volume occupied by each high copper content material (high copper content material 37, 38). Is set to 1: 2. Further, the volume occupied by the high copper content material 36 is set to be approximately the same as the volume occupied by each low copper content material (low copper content materials 34, 35).

The DC motor B of this embodiment is composed of a commutator piece 12
On the other hand, the brush 3 becomes familiar to the user early, and the sliding noise due to the contact between the commutator piece 12 and the brush 3 can be reduced from the initial stage of operation. It should be noted that high output can be secured by energizing a large current, and the life of the brush 3 can be extended (cumulative operation for about 48 hours).

Next, a third embodiment of the present invention (claims 1 to 3)
DC motor C according to (corresponding to No. 4) will be described based on FIGS. 1 to 3 and 6. The brush 3 shown in FIG. 6 has high copper content materials 301, 302, 303 and low copper content materials 304, 305.
Are alternately laminated (described later) in the radial direction. -In order from the commutator piece 12 side, the order of the high copper content material 301, the low copper content material 304, the high copper content material 302, the low copper content material 305, and the high copper content material 303. Further, the contact surface of the high copper content material 301, which is in contact with each commutator piece 12, is flat.

The high copper content materials 301 and 303 are metal graphite materials having a high copper content (65% by weight). The high copper content material 302 is a metal graphite material having a high copper content (55% by weight).

The low copper content materials 304 and 305 are high carbonaceous materials having a low copper content (45% by weight). further,
The ratio of the volume occupied by each low copper content material (low copper content materials 304 and 305) and the volume occupied by the high copper content materials 301 and 302 is set to 1: 2.

High copper content material 30 located on the outer diameter side of the brush 3.
The copper content of 2 (excluding the high copper content material 303 located on the outermost diameter side) is set to the high copper content material 301 located on the inner diameter side of the brush 3.
It is smaller than the copper content of. As a result, the brush wear speed and the roughening speed of the commutator piece are reduced, and the life of the brush 3 can be extended. The DC motor C that employs this brush 3 has a long service life (about 5
5 hours) can be achieved.

Next, a fourth embodiment of the present invention (claims 1 to 1)
DC motor D according to (corresponding to 5) will be described based on FIGS. 1 to 3 and 7. The brush 3 shown in FIG. 7 has high copper content materials 311, 312, 313 and low copper content materials 314, 315.
Are alternately laminated (described later) in the radial direction. The order of the high copper content material 311 to the low copper content material 314 to the high copper content material 312 to the low copper content material 315 to the high copper content material 313 in this order from the commutator piece 12 side. Further, the contact surface of the high copper content material 311 that contacts each commutator piece 12 is flat.

The high copper content materials 311 and 313 are metal graphite materials having a high copper content (65% by weight). The high copper content material 312 is a metal graphite material having a high copper content (55% by weight).

The low copper content materials 314 and 315 are high carbonaceous materials having a low copper content (45% by weight). further,
The ratio of the volume occupied by each low copper content material (low copper content materials 314, 315) to the volume occupied by the high copper content material 311 and the high copper content material 312 is 1: 2: 3. As a result, the operating period in which the brush wear speed and the rough damage speed of the commutator piece 12 decrease becomes longer, and therefore the DC motor D employing this brush 3 is used.
Extends the life of brush 3 (cumulative operation over about 46 hours)
Can be achieved.

Next, a DC electric motor E (corresponding to claims 1, 2, and 3) according to a fifth embodiment of the present invention will be described with reference to FIGS. 1 to 3 and 8. The brush 3 shown in FIG. 8 includes high copper content materials 321, 322, 323, 324 and a low copper content material 32.
5, 326 and 327 are alternately (to be described later) laminated in the radial direction.

High copper content material 32 in order from the commutator piece 12 side
1 to Low Copper Content Material 325 to High Copper Content Material 322 to Low Copper Content Material 326
-High copper content 323-Low copper content 327-High copper content 324 in this order. Further, the contact surface of the high copper content material 321 that is in contact with the commutator piece 12 is flat.

The high copper content material 321 has a copper content of 80% by weight.
Is a metallic graphite material. High copper content materials 322, 323, 32
No. 4 is a metallic graphite material having a copper content of 60% by weight. The low copper content materials 325, 326, 327 are high carbonaceous materials having a copper content of 45% by weight.

Further, in this embodiment, the volume occupied by each low copper content material (low copper content material 325, 326, 327) and the volume occupied by each high copper content material (high copper content material 322, 323). Ratio is 1: 2. Furthermore, the volume occupied by the high copper content material 321 is the low copper content material (low copper content material 325, 326, 327).
It is about the same as the volume occupied by.

The DC motor E of this embodiment is composed of a commutator piece 12
On the other hand, the brush 3 becomes familiar to the user early, and the sliding noise due to the contact between the commutator piece 12 and the brush 3 can be reduced from the initial stage of operation. Further, it is possible to secure a high output by energizing a large current, and to extend the life of the brush 3 (about 40 hours or more in cumulative operation).

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a DC motor according to first to fifth embodiments of the present invention.

FIG. 2 is an explanatory view around brush holders of those DC motors.

FIG. 3 is a cross-sectional view around brush holders of those DC motors.

FIG. 4 is an explanatory diagram of a brush of the DC motor according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a brush of a DC motor according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a brush of a DC electric motor according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a brush of a DC electric motor according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a brush of a DC electric motor according to a fifth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing another example of the brush spring.

[Explanation of symbols]

A, B, C, D, E DC motor 1 commutator 2 armature 3 brush 4 brush holding means 11 shaft (rotating shaft) 12 commutator piece 30 pigtail 31, 32, 33, 36, 37, 38, 39, 301 ,
302, 303, 311, 312, 313, 321, 3
22, 323, 324 High copper content materials 34, 35, 304, 305, 314, 315, 32
5,326,327 Low copper content materials

Claims (6)

[Claims] 1. An armature having a commutator formed by radially arranging a plurality of commutator pieces on the outer circumference of a rotating shaft to form a commutator, and a high copper content material and a low copper content material in a radial direction from an inner diameter side. A direct current electric motor comprising: a plurality of brushes, which are alternately laminated and have a pigtail connected to a high copper content material located on the outermost diameter side, and a brush pressure contact means for contacting each brush with the commutator piece at a predetermined pressure. 2. The high copper content material is a metallic graphite having a copper content of 55% by weight or more, and the low copper content material has a copper content of 55%.
The DC motor according to claim 1, which has a high carbon content of less than wt%. 3. The volume ratio occupied by each low copper content material is made smaller than the volume ratio occupied by a high copper content material adjacent to the outer diameter side of the low copper content material. Two
DC motor described. 4. Excluding the high copper content material located on the outermost diameter side,
The copper content of the high copper content material located on the outer diameter side of the brush,
The DC motor according to any one of claims 1 to 3, wherein the brush content is smaller than the copper content of the high copper content material located on the inner diameter side of the brush. 5. The volume ratio occupied by the high copper content material positioned on the outer diameter side of the brush is set larger than the volume ratio occupied by the high copper content material positioned on the inner diameter side of the brush. The DC motor according to any one of claims 1 to 4. 6. The high copper content material having a copper content ratio higher than that of each of the high copper content materials is arranged at a portion in contact with the commutator element in an initial stage of operation. The DC motor according to claim 5.