WO2022234764A1

WO2022234764A1 - Electric contact member, brush, and rotator

Info

Publication number: WO2022234764A1
Application number: PCT/JP2022/017492
Authority: WO
Inventors: 祥広足立; 敬弘野須; 純哉関川
Original assignee: 株式会社デンソー; 国立大学法人静岡大学
Priority date: 2021-05-07
Filing date: 2022-04-11
Publication date: 2022-11-10
Also published as: JPWO2022234764A1

Abstract

An electric contact member (1) has a contact surface (11) for facing an counterpart member. The electric contact member (1) includes: carbon particles (12); copper particles (13); and a low ionization-potential metal (14) having a lower ionization potential than copper. A brush (10) comprises the electric contact member (1). A rotator (2) comprises the brush (10). In a scanning electron microscope image of the contact surface (11) of the electric contact member (1), the low ionization-potential metal (14) is preferably provided within a circle (3) having a diameter of 50 μm, regardless of where the circle (3) is disposed on the scanning electron microscope image.

Description

Electrical contact members, brushes, and rotating machines

Cross-reference to related applications

This application is based on Japanese Application No. 2021-079010 filed on May 7, 2021, and the contents thereof are incorporated herein.

The present disclosure relates to electrical contact members, brushes, and rotating machines.

Conventionally, in various fields, electrical contact members have been used to achieve electrical connection with mating materials. For example, in the field of rotating machines such as motors, there are known brushes having contact surfaces that are brought into sliding contact with a mating commutator.

Specifically, for example, in Patent Document 1, zinc as a low boiling point material having a boiling point lower than that of copper is added to the electrical contact member, and zinc vapor increases the vapor density during arc discharge to suppress the electron velocity. Techniques for reducing electromagnetic noise have been disclosed.

JP 2020-68653 A

The conventional technology has the following issues. That is, zinc is more difficult to thermally ionize than copper. Therefore, according to the prior art, it is necessary to add a large amount of zinc in order to reduce electromagnetic noise. Therefore, zinc oxide tends to deposit on the surface of the mating material such as the commutator, and the contact resistance tends to increase. Further, if this electrical contact member is applied to a motor brush or the like, there is a possibility that problems such as a decrease in motor efficiency may occur.

An object of the present disclosure is to provide an electrical contact member capable of reducing electromagnetic noise without adding a large amount of zinc, and a brush and rotating machine using the same.

One aspect of the present disclosure has a contact surface for facing a mating member,
carbon particles;
copper particles;
a low ionization voltage metal having a lower ionization voltage than copper;
An electrical contact member comprising:

Another aspect of the present disclosure is a brush having the electrical contact member.

Yet another aspect of the present disclosure is a rotating machine having the brush.

The electrical contact member has the above configuration. Therefore, in the electrical contact member, when arc discharge occurs between the contact surface and the mating material, thermal ionization of the low ionization voltage metal occurs prior to the copper that constitutes the copper particles that are the conductive material. , the electron density in the arc space increases. Therefore, according to the electrical contact member, compared to the case where the electron density in the arc space is low, the force for moving electrons when the same current is applied, that is, the electric field intensity can be reduced. Therefore, the electrical contact member can reduce electromagnetic noise without adding a large amount of zinc.

The brush has the electrical contact member. Therefore, in the above brush, thermal ionization of the low ionization voltage metal occurs during arc discharge when sliding contact and separation are performed between the commutator, which is the mating material, and the contact surface of the electrical contact member, and the arc space The electron density in is increased, making it possible to reduce electromagnetic noise.

The rotating machine has the brush. As a countermeasure against electromagnetic noise, therefore, the rotating machine described above can eliminate a filter composed of coils, capacitors, and the like, a metal shield housing, and the like. Therefore, according to the rotating machine, it is possible to reduce the size, weight, and cost of the rotating machine.

It should be noted that the symbols in parentheses described in the claims indicate the correspondence with specific means described in the embodiments described later, and do not limit the technical scope of the present disclosure.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is a diagram schematically showing a brush of Embodiment 1 to which the electrical contact member of Embodiment 1 is applied; FIG. 2 is a diagram schematically illustrating a part of a scanning electron microscope image of the contact surface of the electrical contact member of Embodiment 1, FIG. 3 is an explanatory diagram for explaining the electrical contact member and the brush of Embodiment 3, (a) is a spherical powder of low ionization voltage metal used for manufacturing the electrical contact member and brush of Embodiment 3 FIG. 11 is a diagram showing an example, and (b) is a diagram showing an example of foil-like powder of a low-ionization voltage metal used for manufacturing the electrical contact member and the brush of Embodiment 3, 4A and 4B are explanatory diagrams for explaining the electrical contact member and the brush of Embodiment 4, and FIG. There is, (b) is a diagram schematically showing a state in which a defect is generated in the oxide film, and the low ionization voltage metal particles are partially metal-bonded at the defect, FIG. 5 is a cross-sectional view along the axial direction of the shaft of the rotating machine of Embodiment 5, FIG. 6 is a diagram schematically showing brushes and a commutator in a rotating machine of Embodiment 5, FIG. 7 is a diagram showing the relationship between temperature (K) and electron density (m ⁻³ ) for each element of Cu, Al, and Zn, obtained in Experimental Example 1. FIG. 8 is a diagram showing the filter voltage values (dB) for the brushes of samples 1 to 4 obtained in Experimental Example 2. FIG. 9 is a scanning electron microscope image of the contact surfaces of the brushes of Samples 1 to 4 obtained in Experimental Example 2. (a) is Sample 1, (b) is Sample 2, ( c) is a scanning electron microscope image of sample 3, and (d) is a scanning electron microscope image of sample 4;

(Embodiment 1)
An electrical contact member and a brush according to Embodiment 1 will be described with reference to FIGS. 1 and 2. FIG. As illustrated in FIGS. 1 and 2, the electrical contact member 1 of this embodiment has a contact surface 11 to face a mating member (not shown in FIGS. 1 and 2). The electrical contact member 1 contains carbon particles 12, copper particles 13, and a low ionization voltage metal 14 whose ionization voltage is lower than that of copper.

The electrical contact member 1 can be suitably used for applications in which an arc is generated between the contact surface 11 and the mating member during use. In addition, the electrical contact member 1 can be suitably used for applications in which the contact surface 11 is in sliding contact with a mating member during use. Specifically, the electrical contact member 1 can be used, for example, as a brush (electrical machine brush) of a rotating machine such as a motor or a generator, an arc welding rod, or the like. In addition, the contact surface 11 may be in contact with the mating member, or may be separated from the mating member.

FIG. 1 shows an example in which the electrical contact member 1 is applied to a brush 10 of a rotating machine (not shown in FIG. 1). The brush 10 of this embodiment has the electrical contact member 1 of this embodiment. Specifically, the brush 10 has a contact portion 101 including the electrical contact member 1 and a lead wire 102 connected to the contact portion 101 . The lead wire 102 is sometimes called a pigtail, and is a portion through which electricity supplied from the outside flows. The brush 10 supplies power through a commutator to an armature coil wound around an iron core provided in a rotor of a rotating machine. In this case, the mating member is a commutator that constitutes a part of the rotor in the rotating machine, and the contact surface 11 is a surface that makes sliding contact with and separates from the mating member. The contact portion 101 may be composed of the electrical contact member 1 as illustrated in FIG. A configuration including a separate member different from the member 1 may be employed. As an example of the latter, for example, an example in which the electrical contact member 1 is formed as a surface layer on the surface of another member can be cited.

The electrical contact member 1 contains carbon particles 12, as illustrated in FIG. The carbon particles 12 form a lubricating film on the mating material when sliding contact and separation are performed between the mating material and the contact surface 11, and are particles useful for preventing fusion with the mating material. is. As the carbon particles 12, graphite particles can be exemplified as a suitable one from the viewpoint of lubricating coating formability, conductivity, cost, material procurement, and the like.

The electrical contact member 1 contains copper particles 13, as illustrated in FIG. The copper particles 13 are base particles of the electrical contact member 1 and are important particles mainly for imparting electrical properties such as conductivity to the electrical contact member 1 .

The electrical contact member 1 contains a low ionization voltage metal 14, as illustrated in FIG. The low ionization voltage metal 14 is a metal with a lower ionization voltage than copper. Also, the low ionization voltage metal 14 is a metal different from copper. The ionization voltage of copper is specifically 7.73 eV. Accordingly, the low ionization voltage metal 14 is selected from metals having an ionization voltage lower than 7.73 eV. The lower the ionization voltage, the less heat energy (J) required for thermal ionization and the increased electron density in the arc space.

Examples of the low ionization voltage metal 14 include Al (aluminum) (ionization voltage: 5.99 eV), Cr (chromium) (ionization voltage: 6.77 eV), Mg (magnesium) (ionization voltage: 7.65 eV), Rb (Rubidium) (ionization voltage: 4.18 eV), Ce (cesium) (ionization voltage: 3.89 eV), and the like can be exemplified. These can be used alone or in combination of two or more. The low ionization voltage metal 14 has a sufficiently low ionization voltage compared to copper, can exist as a solid near room temperature, and can maintain the shape of the electrical contact member 1. , Cr, or the like. These can be used alone or in combination of two or more. The low ionization voltage metal 14 more preferably has a lower ionization voltage, can increase the electron density by adding a small amount, becomes metal vapor at a temperature lower than the boiling point of copper, and is thermally ionized. Al is preferable from the viewpoint that the electrical contact member 1 can be hardened by sintering at a time (for example, when firing at a firing temperature of about 400° C. or higher and 1000° C. or lower). The melting point and boiling point of each metal are Al (melting point: 660°C, boiling point: 2467°C), Cr (melting point: 1857°C, boiling point: 2672°C), Mg (melting point: 639°C, boiling point: 1090°C), Rb (melting point: 39°C, boiling point: 688°C) and Ce (melting point: 29°C, boiling point: 678°C). Further, the low ionization voltage metal 14 is not limited to being a single element, and similar effects can be obtained even if it is contained as a compound (including thermal separation and thermal reduction).

The low-ionization voltage metal 14 may be included in the electrical contact member 1 as particles of the low-ionization-voltage metal 14 (hereinafter sometimes referred to as low-ionization-voltage metal particles 140), for example, as illustrated in FIG. can. According to this configuration, the electrical contact member 1 can be relatively easily manufactured by molding and firing a mixed powder containing carbon powder, copper powder, and low-ionization-voltage metal powder. In addition to the above, the low ionization voltage metal 14 can be included in the electrical contact member 1 as, for example, a coating layer (not shown) that covers the surfaces of the copper particles 13 . In this case, the coating layer can be formed by vapor-depositing the low ionization voltage metal 14 on the surface of the copper particles 13, or the like.

Specifically, FIG. 2 shows an example in which the electrical contact member 1 includes carbon particles 12 , copper particles 13 , and low-ionization-voltage metal particles 140 . More specifically, the electrical contact member 1 can be composed of a sintered body containing a plurality of carbon particles 12 , a plurality of copper particles 13 and a plurality of low-ionization-voltage metal particles 140 .

The electrical contact member 1 can further contain a low boiling point metal (not shown). A low boiling point metal is a metal with a boiling point lower than that of copper. According to this configuration, the low boiling point metal becomes metal vapor at a temperature lower than the boiling point of copper, and the air in the arc space can be eliminated. Nitrogen and oxygen contained in the air are difficult to thermally ionize, so the metal vapor of the low boiling point metal removes the air in the arc space, promoting the thermal ionization of the low ionization voltage metal and increasing the electron density in the arc space. easier. Note that the boiling point of copper is specifically 2567°C. Accordingly, the low boiling point metal can be selected from metals having a boiling point below 2567°C. The low boiling point metal is a metal different from the low ionization voltage metal 14, and if it has a boiling point lower than that of copper, it may have an ionization voltage lower than that of nitrogen or oxygen and higher than that of copper.

Examples of low boiling point metals include Zn (zinc) (boiling point: 907°C, ionization voltage: 9.39 eV), Mg (magnesium) (boiling point: 1090°C, ionization voltage: 7.65 eV), and the like. . These can be used alone or in combination of two or more. Zn can be selected as the low-boiling-point metal from the viewpoint that it has a lower boiling point and is easy to obtain the effect of removing air in the arc. In addition, as the low boiling point metal, Mg can be selected from the viewpoint that it has a lower boiling point than copper and an increase in electron density due to thermal ionization because it has a lower ionization voltage than copper.

The low boiling point metal can be contained in the electrical contact member 1 as, for example, low boiling point metal particles (hereinafter sometimes referred to as low boiling point metal particles). According to this configuration, the electrical contact member 1 can be relatively easily manufactured by molding and firing a mixed powder containing carbon powder, copper powder, low-ionization-voltage metal powder, and low-boiling-point metal powder. .

Although not shown, the electrical contact member 1 may specifically include, for example, carbon particles 12, copper particles 13, low ionization voltage metal particles 140, and low boiling point metal particles. In this case, more specifically, the electrical contact member 1 includes a plurality of carbon particles 12, a plurality of copper particles 13, a plurality of low ionization voltage metal particles 140, and a plurality of low boiling point metal particles. It can consist of a body.

As illustrated in FIG. 2, the electrical contact member 1 has a circle 3 with a diameter of 50 μm at any position on the scanning electron microscope (hereinafter sometimes referred to as SEM) image of the contact surface 11. Even if they are arranged, it is possible to have a configuration in which the low ionization voltage metal 14 that fits within the circle 3 exists. A circle 3 with a diameter of 50 μm is related to the arc bright spot diameter of the arc generated between the contact surface 11 and the mating member. Arc voltage varies depending on the material with which the arc bright spot is in contact. According to the above configuration, the material forming the electrical contact member 1 can be reduced in particle size and uniformly dispersed. According to the above configuration, even if an arc is generated at any position on the contact surface 11 and the arc moves, it is advantageous in suppressing arc voltage fluctuations. Further, according to the above configuration, regardless of the position and movement of the arc, the low-ionization-voltage metal 14 that fits within the diameter of the bright spot of the arc is always likely to exist. Therefore, according to the above configuration, thermal ionization of the low ionization voltage metal 14 can be reliably generated regardless of the position and movement of the arc, and the electron density in the arc space can be increased.

When the electrical contact member 1 contains a low boiling point metal, the electrical contact member 1 is a low boiling point metal that fits within the circle 3 in the SEM image of the contact surface 11 regardless of the position of the circle 3 on the SEM image. can be configured to exist. According to the above configuration, the material forming the electrical contact member 1 can be reduced in particle size and uniformly dispersed. According to the above configuration, even if an arc is generated at any position on the contact surface 11 and the arc moves, it is advantageous in suppressing arc voltage fluctuations. Moreover, according to the above configuration, regardless of the position or movement of the arc, it is easy to always have the low boiling point metal within the diameter of the bright spot of the arc. Therefore, according to the above configuration, the metal vapor of the low boiling point metal can be reliably generated regardless of the position and movement of the arc, and the air in the arc space can be eliminated by the metal vapor of the low boiling point metal. be possible.

Satisfying the above-described configuration involves placing a circle 3 with a diameter of 50 μm on the SEM image of the contact surface 11, moving the circle 3 over the entire area of the SEM image, and finding a low ionization voltage metal 14 or By confirming the presence of low boiling point metals. In acquiring the SEM image, the contact surface 11 can be polished as necessary. The presence of the low-ionization-voltage metal 14 within the circle 3 means that the low-ionization-voltage metal 14 whose entire outline is within the circle 3 exists. Further, the presence of a low boiling point metal that fits within the circle 3 means that there is a low boiling point metal whose entire outline is within the circle 3 . At this time, the outline of the circle 3 passes over the low ionization voltage metal 14 or the low boiling point metal (the outline of the circle 3 overlaps the low ionization voltage metal 14, or the outline of the circle 3 and the low boiling point metal overlap) are excluded. The contours of the low ionization voltage metal 14 and the low boiling point metal are, for example, when the low ionization voltage metal 14 and the low boiling point metal are contained in the electrical contact member 1 as particles, the low ionization voltage metal particles 140 and the low boiling point metal Particle outline.

As illustrated in FIG. 2 , the electrical contact member 1 has carbon particles 12 that fit within the circle 3 in the SEM image of the contact surface 11 even when the circle 3 with a diameter of 50 μm is placed at any position on the SEM image. can be configured to exist. According to the above configuration, the material forming the electrical contact member 1 can be reduced in particle size and uniformly dispersed. According to the above configuration, even if an arc is generated at any position on the contact surface 11 and the arc moves, it is advantageous in suppressing arc voltage fluctuations.

As illustrated in FIG. 2, the electrical contact member 1 has copper particles 13 that fit within the circle 3 in the SEM image of the contact surface 11 even when the circle 3 with a diameter of 50 μm is placed at any position on the SEM image. can be configured to exist. According to the above configuration, the material forming the electrical contact member 1 can be reduced in particle size and uniformly dispersed. According to the above configuration, even if an arc is generated at any position on the contact surface 11 and the arc moves, it is advantageous in suppressing arc voltage fluctuations. The meaning of the carbon particles 12 within the circle 3 and the copper particles 13 within the circle 3 can be understood by applying the above description of the low ionization voltage metal 14 within the circle 3 mutatis mutandis.

Specifically, in FIG. 2, in the SEM image of the contact surface 11 of the electrical contact member 1, the carbon particles 12 that fit within the circle 3 and the circle An example is shown with copper particles 13 falling within circle 3 and low ionization voltage metal particles 140 falling within circle 3 . Although not shown, the electrical contact member 1 may further contain low boiling point metal particles that fit within the circle 3 . In these cases, each material particle (carbon particles 12, copper particles 13, low ionization voltage metal particles 140, low boiling point metal particles, etc.) constituting the electrical contact member 1 can be made small and uniformly dispersed. . When the contact surface 11 of the electrical contact member 1 is in sliding contact with the mating member, such as when the electrical contact member 1 is applied to a brush, the contact surface 11 wears due to the sliding contact, so the arc generation position is different. Easy to position. Therefore, in the above case, even when the contact surface 11 is in sliding contact with the mating member, the arc voltage fluctuation can be suppressed regardless of the position and movement of the arc.

In the electrical contact member 1, the size of the low ionization voltage metal 14 can be set to 1/2 or less of the diameter of the circle 3. Moreover, when the electrical contact member 1 contains a low boiling point metal, the size of the low boiling point metal can be set to 1/2 or less of the diameter of the circle 3 . According to these configurations, arc voltage fluctuations can be easily suppressed regardless of the position and movement of the arc.

The size of the low ionization voltage metal 14 and the low boiling point metal is preferably 2/5 or less of the diameter of the circle 3 from the viewpoint of ensuring the above-mentioned effects, more preferably the diameter of the circle 3 3/10 or less, more preferably 1/5 or less of the diameter of the circle 3, still more preferably 1/10 or less of the diameter of the circle 3.

To satisfy the above configuration, a size confirmation circle (not shown) having a predetermined diameter is applied to the circle 3 having a diameter of 50 μm on the SEM image of the contact surface 11, and the size is confirmed in the entire area of the SEM image. By moving the circle for size confirmation at each position, it is confirmed that the low ionization voltage metal 14 and the low boiling point metal are contained within the circle for size confirmation. The low ionization voltage metal 14 being contained within the size confirmation circle means that the entire contour of each low ionization voltage metal 14 is within the size confirmation circle. Further, the low boiling point metal being contained within the size confirmation circle means that the entire contour of each low boiling point metal is within the size confirmation circle. At this time, the outline of the size confirmation circle passes over the low ionization voltage metal 14 or the low boiling point metal (the outline of the size confirmation circle overlaps the low ionization voltage metal 14, or the size Those where the outline of the confirmation circle and the low boiling point metal overlap) are excluded. When the low ionization voltage metal 14 and the low boiling point metal are contained in the electrical contact member 1 as particles, the low ionization voltage metal particles 140 and the low boiling point metal particles are granulated. diameter.

Specifically, in FIG. 2, each particle size of the carbon particles 12, the copper particles 13, and the low-ionization-voltage metal particles 140 can be set to 1/2 or less of the diameter of the circle 3. Although not shown, if the electrical contact member 1 further contains low boiling point metal particles that fit within the circle 3, the particle size of the low boiling point metal particles should be 1/2 or less of the diameter of the circle 3. can be The particle diameters of the carbon particles 12, the copper particles 13, the low-ionization-voltage metal particles 140, and the low-boiling-point metal particles are preferably equal to the diameter of the circle 3 from the viewpoint of ensuring the above-described effects. 2/5 or less, more preferably 3/10 or less of the diameter of the circle 3, more preferably 1/5 or less of the diameter of the circle 3, still more preferably 1/10 or less of the diameter of the circle 3 can be done. The particle diameters of the carbon particles 12 and the copper particles 13 can be understood by applying the description of the sizes of the low ionization voltage metal 14 and the low boiling point metal described above.

In the electrical contact member 1, the content of the carbon particles 12 is 25 mass from the viewpoint of effectively suppressing fusion between the contact surface 11 and the mating member when the contact surface 11 is brought into sliding contact with the mating member. % or more and 85 mass % or less. Moreover, the content of the copper particles 13 can be selected from the range of 15% by mass or more and 75% by mass or less from the viewpoint of electrical properties such as electrical conductivity of the electrical contact member 1 . The content of the low-ionization voltage metal 14 is selected from the range of 2% by mass or more and 75% by mass or less from the viewpoints of ensuring the effect of addition, suppressing deterioration of electrical and mechanical coupling, raw material cost, etc. be able to. In addition, the content of the low boiling point metal can be selected from the range of 2% by mass or more and 30% by mass or less from the viewpoint of ensuring the effect of the addition and suppressing the increase of the insulating oxide film. In addition, the selection of the mass % is performed so that the total is 100 mass %.

In the electrical contact member 1 of the present embodiment, when arc discharge occurs between the contact surface 11 and the mating member, the low ionization voltage metal 14 precedes the copper constituting the copper particles 13 that are the conductive material. thermal ionization occurs, increasing the electron density in the arc space. Therefore, according to the electrical contact member 1 of the present embodiment, compared to the case where the electron density in the arc space is low, the force for moving electrons when the same current is applied, that is, the electric field strength can be reduced. Therefore, the electrical contact member 1 of this embodiment can reduce electromagnetic noise without adding a large amount of zinc.

The brush 10 of this embodiment has the electrical contact member 1 of this embodiment. Therefore, in the brush 10 of the present embodiment, during arc discharge when sliding contact and separation are performed between the commutator as a mating material and the contact surface 11 of the electrical contact member 1, the low ionization voltage metal 14 Thermal ionization occurs, increasing the electron density in the arc space and making it possible to reduce electromagnetic noise.

(Embodiment 2)
An electrical contact member and a brush of Embodiment 2 will be described. It should be noted that, of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the previously described embodiments represent the same components and the like as those in the previously described embodiments, unless otherwise specified.

In the electrical contact member 1 of this embodiment, part or all of the copper particles 13 are replaced with replacement particles (not shown) made of a metal different from copper. In other words, in the electrical contact member 1 of the present embodiment, at least part of the copper particles 13 are replaced with replacement particles.

Examples of substituted particles include Al particles and Cr particles. When the replacement particles are Al particles, there are advantages such as light weight, low cost, easy material procurement, and low risk of depletion of reserves. Further, when the substituted particles are Cr particles, there are advantages such as increased mechanical strength and improved wear resistance.

In the case where the replacement particles are Al particles or the like, when the metal constituting the replacement particles can function as a low ionization voltage metal, the electrical contact member 1 includes, for example, carbon particles 12 and copper particles 13. , replacement particles, or a configuration including carbon particles 12 and replacement particles.

Further, the brush 10 of this embodiment has the electrical contact member 1 of this embodiment.

The description of the copper particles in Embodiment 1 can be applied mutatis mutandis to the replacement particles. Other configurations and effects are the same as those of the first embodiment.

(Embodiment 3)
An electrical contact member and a brush according to Embodiment 3 will be described with reference to FIG. In the electrical contact member 1 of Embodiment 3, the low ionization voltage metal 14 is composed of spherical particles or foil-like particles. FIG. 3(a) is a diagram showing an example of spherical powder of low ionization voltage metal 14 used for manufacturing the electrical contact member 1 and the brush 10 (described later) of Embodiment 3, and FIG. 3(b). [Fig. 10] is a view showing an example of foil-like powder of a low-ionization-voltage metal 14 used for manufacturing an electrical contact member 1 and a brush 10 (described later) of Embodiment 3. [Fig. The material of the spherical powder and the foil-like powder of the low ionization voltage metal 14 illustrated in FIG. 3 is specifically Al.

When the low-ionization-voltage metal 14 is composed of spherical particles, carbon powder for containing the carbon particles 12 and the low-ionization-voltage metal 14 composed of spherical particles are used when manufacturing the electrical contact member 1. A mixed powder containing spherical powder of the low ionization voltage metal 14 for inclusion is prepared. Since the spherical powder of the low ionization voltage metal 14 is excellent in uniform dispersibility with the carbon powder, according to the above configuration, the low ionization voltage metal 14 composed of the carbon particles 12 and spherical particles is excellent in uniform dispersibility. An electrical contact member 1 is obtained. The spherical powder of the low-ionization-voltage metal 14 can be prepared using, for example, an atomizing method.

On the other hand, when the low ionization voltage metal 14 is composed of foil-like particles, there are the following advantages. As described above, when the low-ionization-voltage metal 14 is composed of spherical particles, the contact between the spherical particles is less than when the low-ionization-voltage metal 14 is composed of foil-shaped particles. Since the surface of the particles is smooth, the mechanical and electrical coupling forces are small, and the spherical particles may fall off during sliding, which may increase the electrical resistance of the electrical contact member 1 . On the other hand, when the low ionization voltage metal 14 is composed of foil-like particles, the foil-like particles tend to entangle with each other, so that the mechanical and electrical bonding strengths are improved, and the foil-like particles fall off during sliding. Therefore, it is possible to suppress an increase in the electrical resistance of the electrical contact member 1 . As the foil-like powder of the low-ionization voltage metal 14 used in manufacturing the electrical contact member 1, for example, a powder obtained by pulverizing the foil of the low-ionization-voltage metal 14 (pulverized foil powder) can be suitably used.

The shape of the low ionization voltage metal 14 included in the electrical contact member 1 can be specified by observing the cross-sectional cut surface of the electrical contact member 1 with an SEM or the like. Spherical particles have a perfect circular or elliptical outer shape. On the other hand, in foil-like particles, the outer shape of the corners of the particles is neither perfect circle nor ellipse. Therefore, both particles can be distinguished relatively easily. Other configurations and effects are the same as those of the electrical contact members 1 of the first and second embodiments.

The brush 10 of this embodiment has the electrical contact member 1 of this embodiment. Therefore, when the electrical contact member 1 has the low ionization voltage metal 14 composed of spherical particles, the carbon particles 12 and the low ionization voltage metal 14 composed of spherical particles are uniformly dispersed. is obtained. In addition, when the electrical contact member 1 has the low ionization voltage metal 14 composed of foil-like particles, the foil-like particles are less likely to fall off during sliding, and an increase in electrical resistance due to this can be suppressed. A brush 10 is obtained. Other configurations and effects are the same as those of the brushes 10 of the first and second embodiments.

(Embodiment 4)
An electrical contact member and a brush according to Embodiment 4 will be described with reference to FIG. As illustrated in FIG. 4, in the electrical contact member 1 of Embodiment 4, the low ionization voltage metal 14 is included in the electrical contact member 1 as particles of the low ionization voltage metal 14 (low ionization voltage metal particles 140). there is In the electrical contact member 1 containing the low ionization voltage metal particles 140, the microstructure of the low ionization voltage metal particles 140 is at least one of the microstructures illustrated in FIGS. can be A specific description will be given below.

In FIG. 4(a), the entire surface of the low ionization voltage metal particles 140 is covered with an oxide film 141. In FIG. No missing portion 141a is generated in the oxide film 141, and no partial metal bonding is generated between the low ionization voltage metal particles 140. FIG. The electrical contact member 1 having the microstructure illustrated in FIG. 4(a) is, for example, heated to a temperature that does not exceed the melting point of the low ionization voltage metal 14 (does not cause deformation) during firing in the manufacture of the electrical contact member 1. It can be produced by firing at. When the low ionization voltage metal 14 is Al, for example, the melting point of Al is about 660.degree.

On the other hand, in FIG. 4(b), for example, firing at a temperature exceeding the melting point of the low ionization voltage metal 14 causes deformation of the particles due to melting. The surface of the low ionization voltage metal particles 140 is covered with an oxide film 141 . However, the oxide film 141 has a partial defect 141a, and the low ionization voltage metal particles 140 are partially metal-bonded in the defect 141a. In addition, the metal bonding may be specifically, for example, fusion bonding. Moreover, as illustrated in FIG. 4B, low ionization voltage metal particles 140 having an oxide film 141 with no defects 141a may be included. The electrical contact member 1 having a microstructure as exemplified in FIG. 4B is manufactured by, for example, firing at a temperature equal to or higher than the melting point of the low ionization voltage metal 14 during firing in the manufacture of the electrical contact member 1. can do. The electrical contact member 1 having a microstructure as illustrated in FIG. 4(b) has a lower ionization voltage than the electrical contact member 1 having a microstructure as illustrated in FIG. 4(a). Due to the partial metal bonding between them, the mechanical bonding strength and the electrical bonding strength are improved, the low ionization voltage metal particles 140 are less likely to fall off during sliding, and an increase in the electrical resistance of the electrical contact member 1 can be suppressed. Become. In particular, when the material of the low-ionization-voltage metal particles 140 is Al, a thin oxide film 141 (for example, about 5 nm) tends to be formed on the surface of the low-ionization-voltage metal particles 140 during firing. The oxide film 141 reduces the mechanical bonding force between particles and increases electrical resistance due to its insulating properties. Therefore, according to the electrical contact member 1 having the microstructure illustrated in FIG. It becomes possible to fully exhibit the effect of this. It should be noted that the density of the partial metal bonding can differ, for example, in the depth direction of the electrical contact member 1 . This is because the firing temperature may differ in the depth direction of the electrical contact member 1 during manufacturing.

In addition, the microstructure of the low ionization voltage metal particles 140 in the electrical contact member 1 is obtained by EPMA (X-ray elemental mapping) analysis of the cross-sectional cut surface of the electrical contact member 1, and the oxide film 141 provided on the surface of the low ionization voltage metal particles 140 It can be grasped by confirming the presence or absence of the missing portion 141a. If there is a missing portion 141a in the oxide film 141, it can be said that metal bonding between the low ionization voltage metal particles 140 has occurred. Other configurations and effects are the same as those of the electrical contact members 1 of the first and second embodiments.

The brush 10 of this embodiment has the electrical contact member 1 of this embodiment. In particular, in the electrical contact member 1, the oxide film 141 on the surface of the low ionization voltage metal particles 140 has a defect 141a, and the low ionization voltage metal particles 140 are partially metal-bonded at the defect 141a. In this case, the low ionization voltage metal particles 140 are less likely to come off during sliding, and the brush 10 can be obtained which can suppress an increase in electrical resistance caused by this. Other configurations and effects are the same as those of the brushes 10 of the first and second embodiments.

(Embodiment 5)
A rotating machine according to Embodiment 5 will be described with reference to FIGS. 5 and 6. FIG. As illustrated in FIGS. 5 and 6, the rotating machine 2 of this embodiment has the brush 10 of the first embodiment. Specifically, the rotating machine 2 is a rotating electrical machine, and more specifically, is configured as a DC motor with brushes. The rotating machine 2 can be used, for example, as a motor for driving an on-vehicle device, a motor for driving household electricity, a motor for driving general industrial machines, and a motor for driving various devices. The rotating machine 2 may be configured as an electric motor, or may be configured as a motor-generator having both functions of an electric motor and a generator.

In this embodiment, the axial direction of the shaft 20 constituting the rotating machine 2 is indicated by the arrow X, and the radial direction of the shaft 20 is indicated by the arrow Y, unless otherwise specified. The direction of rotation, which is one of the circumferential directions of the shaft 20, is indicated by an arrow Za.

The rotating machine 2 has a cylindrical shaft 20 that is a rotating shaft, and is configured such that the shaft 20 is rotationally driven by electric power supplied from the power source E. The rotating machine 2 includes a housing 22 composed of a case 23 and a cover 24, and a plurality of components for rotationally driving the shaft 20. The plurality of components are accommodated within the housing 22. . The plurality of components include a plurality of supports 25 that rotatably support the shaft 20, a rotor 220 as a rotor, a commutator 231, two

brushes

10, 10, and a magnet 240 as a stator. include.

The rotor 220 is fixed to the shaft 20. The rotor 220 has an iron core 221 formed by laminating a plurality of electromagnetic steel sheets and an armature coil 222 , and the armature coil 222 is wound around the iron core 221 .

The magnet 240 is fixed to the inner surface of the case 23 forming the housing 22 with a gap between it and the rotor 220 . The magnet 240 has a function of applying a magnetic field to the armature coil 222, and is configured as a magnetic field permanent magnet (S pole and N pole) having mutually different polarities.

The commutator 231 has a plurality of commutator segments 232 and is electrically connected to the armature coils 222 . As shown in FIG. 6 , a plurality of commutator segments 232 are arranged side by side in the circumferential direction of the shaft 20 in the commutator 231 . Adjacent commutator bars 232 are circumferentially spaced from each other and electrically connected to each other by armature coils 222 .

Both of the two brushes 10 are rectangular brushes that are electrically connected to the power source E and are in sliding contact with the plurality of commutator segments 232 as the commutator 231 rotates. One first brush 10 is electrically connected to the positive terminal of the power supply E. As shown in FIG. The other second brush 10 is configured to be electrically connected to the negative terminal of the power source E and paired with the first brush 10 . The two brushes 10 are arranged at positions shifted by 180° in the circumferential direction. Therefore, the first brush 10 can be called a "positive brush" and the second brush 10 can be called a "negative brush".

The first brush 10 is capable of sliding contact and separation with the plurality of commutator bars 232 , and when slidingly contacted or separated, the first brush 10 is relatively potential with respect to the plurality of commutator bars 232 . becomes higher. The second brush 10 is capable of sliding contact and separation with the plurality of commutator bars 232, and when slidingly contacted or separated, the second brush 10 is relatively potential with respect to the plurality of commutator bars 232. becomes lower. Thus, each of the plurality of commutator bars 232 can be on the high potential side or the low potential side depending on the sliding contact relationship with the two brushes 10 . In this embodiment, both of the two brushes 10 are constructed using the electrical contact member 1 .

The rotating machine 2 of this embodiment has the brush 10 of the first embodiment. Therefore, in the rotating machine 2 of the present embodiment, it is possible to eliminate filters configured by coils, capacitors, and the like, metal shield housings, and the like as countermeasures against electromagnetic noise. Therefore, according to the rotating machine 2 of the present embodiment, it is possible to reduce the size, weight, and cost of the rotating machine 2 .

In addition, in the present embodiment, the input power of the rotating machine 2 is not particularly limited, but can be, for example, 10 W or more and 800 W or less. In this case, the effect of the above-described electrical contact member 1 is sufficiently exhibited in relation to the size of the diameter of the arc bright spot of the arc formed between the electrical contact member 1 of the brush and the commutator 231. be able to.

Further, in the present embodiment, the case where the rotating machine 2 has the brush 10 of Embodiment 1 has been described, but the rotating machine 2 may have the brush 10 having the electrical contact member 1 of Embodiments 2 to 4. good.

(Experimental example 1)
For each element Cu (ionization voltage: 7.72 eV), Al (ionization voltage: 5.99 eV), and Zn (ionization voltage: 9.39 eV) ^, it is defined by temperature and the number of thermally ionized electrons per 1m The relationship with electron density was determined by simulation. In this simulation, it was assumed that the elements Cu, Al, and Zn were all gasified (vaporized) at atmospheric pressure regardless of temperature. At this time, it was assumed that each element was in a 100% metallic gas state and that no air (N ₂ , O ₂ ) was mixed. Further, the electron density was obtained by calculating the number of electrons ionized from the thermally ionized energy for each element. FIG. 7 shows the relationship between temperature (K) and electron density (m ⁻³ ) for each element of Cu, Al, and Zn. In this experimental example, a compact brushed DC motor with an input power of 50 W was assumed, and the arc discharge temperature was set to 4000 K (Kelvin).

According to Figure 7, the following can be seen. Each element of Cu, Al, and Zn is almost 100% ionized (electron density is saturated) above 10000K (9727°C). Zn has a higher ionization voltage than Cu. On the other hand, Al has a lower ionization voltage than Cu. At around 4000K arc discharge temperature, Al can increase the electron density in the arc space compared to Zn. From this, in the electrical contact member containing copper particles, by using Al instead of Zn, that is, by using a low ionization voltage metal such as Al, which has a lower ionization voltage than Cu, the contact surface and the counterpart material When an arc discharge occurs between them, the thermal ionization of the low ionization voltage metal occurs prior to the copper that constitutes the copper particles that are the conductive material, and it becomes possible to increase the electron density in the arc space. I can say. Therefore, according to such an electrical contact member, compared with the case where the electron density in the arc space is small, the force for moving electrons when the same current is applied, that is, the electric field strength can be reduced. It can be said that it is possible to reduce electromagnetic noise without adding

(Experimental example 2)
Cu (copper) powder with an average particle size of 50 μm and C (graphite) powder with an average particle size of 5 μm are blended in a mass ratio of 50:50 (about 20:80 in volume ratio), stirred and mixed. did. Next, the obtained mixed powder was compression-molded in a mold. Next, the obtained compression-molded body was sintered in a deoxidized atmosphere at a temperature at which the components did not undergo thermal change, and was sintered. Thus, a sample 1 brush was produced. The average particle size of the raw material powder refers to the particle size when the volume integrated value in the particle size distribution determined by the laser diffraction/scattering method is 50% (the same shall apply hereinafter).

A sample 2 brush was prepared in the same manner as in the preparation of the sample 1 brush, except that the materials were stirred and mixed so as to improve the uniform dispersibility.

Except for the fact that Cu powder with an average particle size of 20 μm and C powder with an average particle size of 5 μm were blended so that the mass ratio was 50:50 (the volume ratio was about 20:80) in the preparation of the brush of Sample 1. prepared a sample 3 brush in the same manner.

Except for the fact that Cu powder with an average particle size of 2 μm and C powder with an average particle size of 5 μm were blended so that the mass ratio was 50:50 (the volume ratio was about 20:80) in the preparation of the brush of Sample 1. prepared a sample 4 brush in the same manner.

In a sliding electrical contact circuit equivalent to an actual motor using each brush, the voltage waveform between electrical contacts was captured, and the filtered voltage value (magnitude of the voltage waveform) after a 250 MHz bandpass filter was measured. Since the magnitude of the filter voltage value fluctuates depending on the contact state, there is a range. Therefore, data measurement was repeated with the same settings, and the upper limit value, lower limit value, and average value of the filter voltage values were obtained. For each sample, the number of samples was 2, the number of repetitions was 4, and n=8. FIG. 8 shows filter voltage values (dB) for the brushes of samples 1 to 4. FIG. 9 shows SEM images of the contact surfaces of the brushes of Samples 1 to 4. FIG. In addition, in FIG. 9, the white part is Cu and the gray part is C. As shown in FIG.

　According to Figures 8 and 9, the following can be understood. As shown in FIGS. 8 and 9, with the brush of sample 1, when a circle with a diameter of 50 μm is placed on the SEM image, each material particle (here, Cu particles and C particles) constituting the electrical contact member does not exist within the above circle. Therefore, the brush of sample 1 had a wide range of filter voltage values. Therefore, it can be said that the brush of sample 1 cannot suppress the arc voltage fluctuation regardless of the position and movement of the arc. The same applies to the sample 2 brush. The brush of sample 2 had the same raw material particle size as the brush of sample 1, but only the dispersibility was improved. On the other hand, in the brushes of Samples 3 and 4, each material particle constituting the electrical contact member exists within the circle regardless of the position of the SEM image where the circle with a diameter of 50 μm is placed. Therefore, in the brushes of Samples 3 and 4, the width of the filter voltage value was narrowed by reducing the particle size of the material particles and achieving uniform dispersion. From this result, it can be said that the brushes of Samples 3 and 4 can suppress the arc voltage fluctuation regardless of the position and movement of the arc. In addition, when comparing the brushes of Samples 1 to 4, the smaller the particle size of the material particles and the more uniform dispersion is promoted, the smaller the width of the filter voltage value becomes, making it easier to suppress arc voltage fluctuations. I understand. It is also found that by setting the particle size of the material particles to 1/2 or less of the diameter of the circle, it becomes easier to ensure that the material particles are present within the circle.

(Experimental example 3)
Cu (copper) powder with an average particle size of 5 μm, C (graphite) powder with an average particle size of 10 μm, and Al (aluminum) powder with an average particle size of 5 μm are blended in a mass ratio of 50:45:5. , were stirred and mixed using a ball mill. Next, the obtained mixed powder was compression-molded in a mold. Next, the obtained compression-molded body was sintered in a deoxidized atmosphere at a temperature at which the components did not undergo thermal change, and was sintered. Thus, a sample 6 brush was obtained. Note that the brush of Sample 6 contains Al particles as the low ionization voltage metal particles.

Cu (copper) powder with an average particle size of 5 μm, C (graphite) powder with an average particle size of 10 μm, Al (aluminum) powder with an average particle size of 5 μm, and Zn (zinc) powder with an average particle size of 5 μm are mixed by mass. They were blended in a ratio of 50:40:5:5 and stirred and mixed using a ball mill. Next, the obtained mixed powder was compression-molded in a mold. Next, the obtained compression-molded body was sintered in a deoxidized atmosphere at a temperature at which the components did not undergo thermal change, and was sintered. Thus, a sample 7 brush was obtained. The brush of Sample 7 contains Al particles as low-ionization-voltage metal particles and Zn particles as low-boiling-point particles.

The present disclosure is not limited to the above embodiments and experimental examples, and various modifications can be made without departing from the scope of the present disclosure. That is, although the present disclosure has been described in accordance with embodiments, it is understood that the present disclosure is not limited to such embodiments, structures, and the like. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure. Moreover, each configuration and each effect shown in each embodiment, each experiment example, and the following reference forms can be combined arbitrarily.

Examples of reference forms are added below.
[Section 1]
An electrical contact member having a contact surface for facing a mating member,
In the scanning electron microscope image of the contact surface,
Even if a circle with a diameter of 50 μm is placed at any position on the scanning electron microscope image,
The material particles that make up the electrical contact member are present within the circle.
Electrical contact member.
According to the electrical contact member of item 1, the particle size of the material particles constituting the electrical contact member 1 can be reduced and uniformly dispersed. Therefore, according to the electrical contact member of item 1 above, it is possible to solve the problem of suppressing the arc voltage fluctuation even when the arc is generated at any position on the contact surface and the arc moves.
[Section 2]
Item 2. The electrical contact member according to Item 1, wherein the particle size of the material particles is set to be 1/2 or less of the diameter of the circle.
According to the electrical contact member of item 2, it is possible to ensure that the material particles constituting the electrical contact member are present within the circle.
[Section 3]
The material particles include copper particles,
Item 3. The electrical contact member according to item 1 or item 2, wherein the particle diameter of the copper particles is set to be 1/2 or less of the diameter of the circle.
[Section 4]
The material particles include low ionization voltage metal particles having a lower ionization voltage than copper,
Item 4. The electrical contact member according to any one of Items 1 to 3, wherein the particle size of the low ionization voltage metal particles is set to 1/2 or less of the diameter of the circle.
[Section 5]
Item 5. The electrical contact member according to Item 4, wherein the metal constituting the low ionization voltage metal particles is at least one metal selected from the group consisting of Al and Cr.
[Section 6]
The material particles contain low boiling point metal particles having a boiling point lower than that of copper,
Item 6. The electrical contact member according to any one of Items 1 to 5, wherein the particle size of the low boiling point metal particles is set to be 1/2 or less of the diameter of the circle.
[Section 7]
Item 7. The electrical contact member according to Item 6, wherein the metal constituting the low boiling point metal particles is at least one metal selected from the group consisting of Zn and Mg.
[Item 8]
The material particles include carbon particles,
Item 8. The electrical contact member according to any one of Items 1 to 7, wherein the particle diameter of the carbon particles is 1/2 or less of the diameter of the circle.
[Item 9]
Some or all of the copper particles are replaced with replacement particles composed of a metal different from copper,
Item 4. The electrical contact member according to item 3.
[Item 10]
A brush comprising the electrical contact member according to any one of items 1 to 9.
According to the brush of item 10, it is possible to obtain a brush capable of suppressing arc voltage fluctuations regardless of the position and movement of the arc.
[Item 11]
Item 11. A rotating machine having the brush according to item 10.
According to the rotating machine of item 11, it is possible to obtain a rotating machine having brushes capable of suppressing arc voltage fluctuations regardless of the position and movement of the arc.

Claims

It has a contact surface (11) for facing the mating material,
carbon particles (12);
copper particles (13);
a low ionization voltage metal (14) having a lower ionization voltage than copper;
An electrical contact member (1) comprising:
In the scanning electron microscope image of the contact surface,
Even if the circle (3) with a diameter of 50 μm is placed at any position on the scanning electron microscope image,
2. The electrical contact member of claim 1, wherein there is said low ionization voltage metal that falls within said circle.
The electrical contact member according to claim 2, wherein the size of the low ionization voltage metal is 1/2 or less of the diameter of the circle.
The electrical contact member according to any one of claims 1 to 3, wherein the low ionization voltage metal is at least one metal selected from the group consisting of Al and Cr.
The electrical contact member according to any one of claims 1 to 4, further comprising a low boiling point metal having a boiling point lower than that of copper.
The electrical contact member according to claim 5, wherein the low boiling point metal is at least one metal selected from the group consisting of Zn and Mg.
Some or all of the copper particles are replaced with replacement particles composed of a metal different from copper,
The electrical contact member according to any one of claims 1 to 6.
A brush (10) having the electrical contact member according to any one of claims 1 to 7.
A rotating machine (2) having the brush according to claim 8.