JP2000004564A - Electrical sliding contact material and small dc motor equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the service life of a small DC motor by restraining the friction of a brush commutator of the small DC motor used for OA, AV apparatus or the like. SOLUTION: In this electrical sliding contact point, where a flat-plate metallic brush 1 in which an electrical sliding contact material formed of any one of Ag, Ag alloy, Cu, and Cu alloy is embedded in a base material, having spring elasticity conducts sliding-energization with a commutator piece 4n having the electrical sliding contact material formed of any one of arc-shaped Ag, Ag alloy, Cu, Cu alloy, an electrical sliding contact material is formed by ion- implanting one, two or more types of metal elements selected from groups IIIa and IIIb elements in the periodic table into the electric sliding contact material of the brush 1 or/and the commutator piece 4n at implantation concentration of 1015-1020 dose (ions/cm2), thus it is possible to restrain wear to the brush commutator and increase the life of the small DC motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric sliding contact material used for a brush and / or a commutator piece of a small DC motor.

[0002]

2. Description of the Related Art FIG. 1 is a perspective external view showing an electric sliding contact material according to the present invention and a brush and a commutator commonly used in the prior art. In the figure, 1 is a brush piece, 2 is a brush-commutator sliding portion, 3 is a brush base, 4 is a commutator, and 5 is a rotating shaft. Here, the brush piece 1 is made of, for example, Cu-Be.
A thin strip formed by embedding an electric sliding contact material 1b such as an Ag-Pd alloy by a so-called cladding method or the like on a base material 1a such as a base alloy. The commutator 4 is made of an electric sliding contact material 4 such as an Ag-Cd alloy.
A plate material in which k and a conductive material 4m such as Cu are compounded by a cladding method or the like is punched, and a plurality of commutator pieces 4n which are bent into an arc shape are embedded in an insulating member 4a.

The above-described electric sliding contact material 1b is constantly pressed by the brush-commutator sliding portion 2 against the electric sliding contact material 4k of the commutator piece 4n due to the spring elasticity of the base material 1a. The electric sliding contact material 1b buried in the surface of the base material 1a is rectified by sliding current with the electric sliding contact material 4k of the commutator piece 4n, generating a rotating magnetic field, and rotating by the electromagnetic force. The small DC motor is driven around the shaft 5.

Therefore, in particular, the electric sliding contact materials 1b, 4k
Considering the electrical characteristics of being excellent in arc resistance, welding resistance, and wear resistance, and having low electric resistance, and the mechanical characteristics that mechanical wear due to intermetallic adhesion due to sliding is small, A
u, Ag, Pd, Pt, Ru, Rh, Cu, Ir, I
1 selected from n, Ni, Sn, Zn, Ru, Be, etc.
One or more alloy ribbons are used.

For example, Japanese Unexamined Patent Publication No. 63-2574 discloses a base material 1a.
Be _{0. 5} ~ _0.15 Fe ≦ 0.2C listed in 37 JP
_{o 0.15 ~ 0.6 Si ≦ 0.2Al Cu} -Be alloys, such as ≦ 0.2, the electrical sliding contact material Ag ₃₀ Pd ₃₅ Cu ₁₄ Pt ₁₀
Examples of the Ag—Pd-based alloy such as Au ₁₀ Zn ₁ and the sliding contact material 4 k of the commutator piece include Au ₆₅ to ₇₅ Pt ₃ to _{7.
Ag 7 ~ 13 Cu 11 ~ 17} Ni 0.5 ~ 1.5 alloy is widely used.

The electric sliding contact member suffers from electrical wear due to arc discharge at the time of current switching due to rectification and mechanical wear due to adhesion between metals. That is, it is known that electrical and mechanical wear characteristics due to commutation and sliding have a significant effect on the drive characteristics of a small DC motor.

In particular, in a frequent drive mode of starting and stopping, the current passing through the sliding contact material increases, so that the current density of the contact portion increases, and electrical wear due to arc spark discharge becomes dominant. This hinders the driving characteristics of the small DC motor and has a drawback of shortening the life.

Accordingly, conductive fine powder having a high resistance to the brush sliding portion, fine powder of oxide of conductive material, fine powder of semiconductive material, carbon, etc. Or a mixture of these in a liquid adhesive is baked to form a resistive layer, thereby suppressing arc spark discharge and suppressing brush abrasion (Japanese Patent Laid-Open No. 54-706). Attempts have been made to improve the abrasion resistance by forming an ion-implanted layer of Ti and C on the surface of a silver-cadmium oxide-based contact material (JP-A-3-246831). However, when a resistance layer is formed on the surface, although there is an arc suppression effect at high voltage,
When the voltage is low, the small DC motor may not be able to start.

On the other hand, not an electrical contact material intended for a sliding contact portion such as a brush and a commutator piece, but an Ag-oxide electrical contact material for an on-off contact portion such as a relay.
g, Zr, Hf, V, Nb, Ta, Cr,
Attempts have also been made to reduce the transfer of material components at the contact points by arcs by ion implantation of elements such as Mo, W, Re, Ru, Os, Rh, Ir, and Pt (Japanese Patent Laid-Open No. 3-203133). Gazette). However, Ag-oxide based electrical contact materials have poor plastic workability, are difficult to be thinned, and have electrical conductivity of Ag, Ag alloy, Cu, Cu.
It cannot be used as an electric sliding contact material for small DC motors because of its lower electric resistance and higher electric resistance than alloys.

In a switching contact portion such as a relay, a contact material made of any of silver, a silver alloy and a silver-oxide system has a surface of Ti, Zr, H having a melting point higher than that of silver.
f, V, Nb, W, Re, Ru, Os, Rh, Ir, P
Attempts have also been made to reduce the transfer of material components at contact portions by arcing by performing ion beam mixing using a combination of thin film growth by vapor deposition of elements such as t and ion implantation of elements such as Ar and O. JP-A-3-20313
No. 5). However, since ion beam mixing is a process involving film formation, the physical properties of the surface, particularly electrical conductivity, are dominated by the film forming material, making it difficult to achieve both mechanical and electrical characteristics. There is a disadvantage that it is difficult to obtain a stable driving characteristic over time.

Although it is not an electrical contact material intended for a sliding contact portion such as a brush and a commutator piece, the surface of a contact base material made of any material of Ag, Ag alloy, Cu, and Cu alloy is Ru, Rh, P by ion implantation
It has been proposed to implant at least one noble metal ion of d, Os, Ir, and Pt to reduce welding and transfer of contacts by arcing (Japanese Patent Laid-Open No. 5-20).
962).

Next, in order to improve the mechanical wear characteristics, for example, a brush having an alloy composition of Au ₁₀ Pt ₁₀ Pd ₃₅ Ag ₃₀ Cu ₁₄ Zn ₁ and a commutator piece having an alloy composition of Au ₇₀ Pt ₅ Ag ₁₀ Cu ₁₄ Ni ₁ A different metal having a thickness of about 0.01 to 3 μm by a method such as sputtering, ion plating, vapor deposition, or CVD, and
Attempts have been made to suppress the adhesion between metals during sliding and improve wear resistance by thermally diffusing at 00 ° C. In such a heat diffusion alloying method,
Nb, In, Ba, Cd (JP-A-63-89035), Sb, Te, Pb, S
e, As, Zn, (JP-A-63-89036),
B, Si, Ge, Tl (JP-A-63-89037), Al, Ga, Mn (JP-A-63-89038) Co, Sn, Ti (JP-A-63-89039) Cr, Mg, Zr, P (JP-A-63-89040) and the like. However, in the process of diffusing a film-forming material by heat, a concentration gradient of a diffusion element from the surface is inevitable, and the physical properties of the surface, particularly electric conductivity, are governed by the film-forming material. There is a disadvantage that it is difficult to achieve both, and it is essentially difficult to obtain stable driving characteristics over time.

[0013]

As described above, the brush and the commutator of the small DC motor made of the metal-based electric sliding contact material are particularly suitable for the arc discharge between the contacts in the frequent sliding mode of starting and stopping. There is a drawback that the wear caused by the motor is severe, which hinders the starting characteristics and shortens the life of the small DC motor.

The present invention provides an electric sliding contact made of a brush or / and a commutator piece of a small DC motor using an electric sliding contact made of a specific surface modification, especially in a frequent sliding mode of starting and stopping. An object of the present invention is to suppress wear caused by arc discharge while maintaining high electrical conductivity of a portion, and extend the life of a small DC motor.

[0015]

SUMMARY OF THE INVENTION According to the present invention, a brush or / and a commutator element are made of Au, Ag, Pd, Pt, Ru,
Rh, Cu, Ir, In, Ni, Sn, Zn, Ru, B
e, one or more alloys selected from the group consisting of a metal element selected from the group IIIa and IIIb elements of the periodic table, especially A
g, a metal whose oxidation activity is higher than that of Cu is ion-implanted into a contact material such as Ag, Ag-based alloy, Cu, or Cu-based alloy without being alloyed with the contact material. It is an electric sliding contact material for DC motors. Further, the present invention provides a method in which a brush or / and a commutator piece is made of Au, Ag, Pd, Pt, Ru, Rh, Cu, I
One or more alloys selected from the group consisting of r, In, Ni, Sn, Zn, Ru and Be are added to the periodic table IIIa, II
A metal element selected from the group Ib elements, in particular, a metal having a higher oxidation activity than Ag and Cu, is ion-implanted into a contact material of Ag, Ag-based alloy, Cu, and Cu-based alloy without being alloyed. An electric sliding contact material for a small DC motor in which a metal oxide of a metal having a higher oxidizing activity than Ag and Cu is dispersed in the contact material by direct ion implantation into the material and then oxidized after the implantation. is there.

In particular, the metal ion species is one or more of Al, Y and Ge, and the implantation amount is 1 × 10 ¹⁵ to 1
× 10 ²⁰ dose (ions / cm ² ), injection depth 0.1 μm to 10
When the thickness is set to 0 μm, the effect of suppressing wear caused by arc discharge can be significantly improved even in a frequent start-stop mode.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The ion implantation of the metal substrate into the electric sliding contact material is performed, for example, by causing an arc discharge in a vacuum to evaporate and ionize the cathode material, accelerated by a grid electrode to which a high voltage is applied, and extracted as an ion beam. inject.

FIG. 2 shows BROWN.
I. G,; "The Metal Vapor Vacuum Arc (MEVVA) High
Current Ion Source ".IEEE Trans.on Nuclear Sience V
FIG. 1 is a configuration diagram of a MEVVA ion beam generator described in ol. NS-32, No. 5 (1985).

In the figure, when an arc discharge occurs between the cathode 6 and the anode 7 in a vacuum, the periodic table IIIa, IIIb
The cathode material made of a metal element selected from the group III elements evaporates and is ionized. When a high voltage is applied to the grid electrode 8, the ions α are accelerated and extracted as a beam β. When the beam β is irradiated on the brush piece 1, ion implantation can be performed.

The metal-based electric sliding contact material is Au,
Ag, Pd, Pt, Ru, Rh, Cu, Ir, In, N
One or more alloy ribbons selected from i, Sn, Zn, Ru, Be, and specific alloy compositions include:
Ag ₅₀ Pd ₅₀ , Ag ₃₀ Pd ₃₅ Cu ₁₄ Pt ₁₀ Au ₁₀ Z
n ₁ , Au ₆₅ to ₇₅ Pt ₃ to ₇ Ag ₇ to ₁₃ Cu ₁₁ to ₁₇ Ni _0.5
~ _1.5 such as Ag, Cu base alloy can be exemplified.

The above-mentioned metal-substrate sliding contact material has a periodic table
The reason for injecting metal elements selected from the group IIIa and IIIb elements is that these elements have a lower oxidative active melting point than Ag and Cu, and easily become metal oxides due to the arc energy at the time of driving the actual machine. This is because, by dispersing the metal oxide in the contact metal, the arc resistance of the contact material can be improved, and the effect of reducing electric wear due to arc discharge can be expected. Further, by adding an oxidation step after the ion implantation, the metal oxide can be more uniformly dispersed.

The depth of the ion implantation is 0.1 μm to 1 μm.
The thickness is preferably 00 μm, and if it is 0.1 μm or less, the effect of reducing electric wear is small. If the injection is 100 μm or more, the energy at the time of injection becomes too high and the surface of the sliding contact material is dissolved.

The degree of vacuum at the time of ion implantation is 10 ^-5 to
10 ^-8 Torr is preferred. At 10 ^-5 Torr or less, impurities are often mixed, and at 10 ^-8 Torr or more, ionization of the cathode material becomes difficult. The ion implantation amount is 10 ¹⁵ -10 ²⁰
dose (ions / cm ²⁾ is preferred, fewer injection effect is 10 ¹⁵ or less. Further, even if it is injected in an amount of 10 ²⁰ or more, the elongation of the performance improvement is small, and a surface crack due to blister is formed on the surface of the electric sliding material, which is not preferable.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

An electric sliding contact material 1b having an alloy composition of Ag ₅₀ Pd ₅₀ was buried in a base material 1a having an alloy composition of CuNiCr with a clad, and adjusted to a total thickness of about 80 μm and a thickness of the sliding contact material of 20 μm by rolling. Metal ions were implanted into the ribbon at an acceleration voltage of 70 kV,
It injected so that it might become x10 ¹⁷ dose (ions / cm ² ).

A thin strip in which the above-mentioned electric sliding contact material 1b was buried by cladding was processed into a brush piece 1 shown in FIG. 1, a brush base 3 was assembled, and a brush into which ions were implanted was produced. As a comparative example, a brush into which metal (Ti) and C were implanted twice and a brush without ion implantation as a conventional example were also prepared.

Separately, the outermost layer is made of Au having a thickness of 1 μm.₆₀Ag₄₀
Alloy, intermediate layer of 30 μm thick Ag ₉₉Cd₁Alloys, more
Made of electric sliding contact material with inner layer of 1mm thick Cu
The commutator piece 4n is formed in an annular shape with an outer diameter of 3 mm, and is used as an insulating member 4a.
A commutator 4 was embedded and fixed.

The small DC mounted with the brush and the commutator.
Table 1 shows the number of times the motor is driven until it stops when the motor is operated in the shift mode shown in FIG. 3 (one cycle of 0.8 sec).

[0030]

[Table 1]

As is clear from Table 1, the metal-based electric sliding contact material such as an Ag-based alloy has a standard free energy of formation of oxide lower than that of Ag or Cu.
When a metal element selected from the group Ia and IIIb and Ti and C are double-injected, this suppresses electrical abrasion of the sliding contact portion due to arc spark discharge and prevents abrasion of commutator pieces and brushes.
As a result, the number of times the small DC motor can be driven in a drive mode in which starting and stopping and shifting are severe can be doubled or more, and a long life and high reliability of the small DC motor can be achieved.

On the other hand, a torque load of 20 g · cm is applied to the output shaft of the small DC motor on which the brush and the commutator are mounted.
Table 2 shows whether or not start-up is possible when the drive voltage is set to 0.4, 0.6, 0.8, and 1.0 V.

[0033]

[Table 2]

As is evident from Table 2, the electric sliding contact material of this embodiment shows a stable starting characteristic even at a low voltage.

On the other hand, as shown in Comparative Examples 1 and 2, IVa, Va, VIa
When C is additionally injected into the group III element, the electric resistance of C is high.
There is a problem that the contact resistance of the sliding portion of the brush commutator becomes high and the brush commutator cannot be started at a low voltage.

From the above results, IIIa,
The electric sliding contact material ion-implanted with a Group IIIb element realizes a long life in a drive mode with a large current load, and also achieves a stable starting characteristic even at a low voltage.

[0037]

As described above, the brush and the commutator of the small DC motor composed of the electric sliding contact material of the metal substrate are particularly suitable for the electric discharge caused by the arc discharge in the frequent sliding mode of starting / stopping and shifting. There is a drawback that the wear is severe, which hinders the driving characteristics and shortens the life of the small DC motor.

The present invention relates to one or two metal elements selected from the group IIIa and IIIb elements of the periodic table, particularly Al, Y and Ge, which have lower standard free energy of formation of oxides than Ag and Cu. By using the ion-implanted electric sliding contact material as a brush and / or a commutator piece of a small DC motor, it is possible to suppress electric wear caused by arc discharge particularly in a sliding mode in which starting and stopping and shifting are frequently performed. The life of the small DC motor can be extended.

[Brief description of the drawings]

FIG. 1 is a perspective external view showing a brush and a commutator.

FIG. 2 is a configuration diagram of an ion beam generator.

FIG. 3 is a drive mode diagram of a small DC motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brush piece 1a Base material 1b Electric sliding contact material 2 Brush commutator sliding part 3 Brush base 4 Commutator 4k Electric sliding contact material 4m Conductive material 4n Commutator piece 5 Rotation axis 6 Cathode 7 Anode 8 Grid electrode α ion β beam

Claims (7)

[Claims] 1. A flat metal brush in which an electric sliding contact material made of one of Ag, an Ag-based alloy, Cu, and a Cu-based alloy is embedded in a base material having a spring elasticity is formed by an arc-shaped Ag. Commutator piece having an electric sliding contact material made of any one of Ag, Ag-based alloy, Cu, and Cu-based alloy, and a brush or / and an electroslider of the commutator piece in an electric sliding contact portion that performs sliding energization. One or two or more metal elements selected from the group IIIa and IIIb elements of the periodic table having a low standard free energy of oxide formation were implanted into the contact material by direct ion implantation. Electric sliding contact material. 2. A flat metal brush in which an electric sliding contact material made of any one of Ag, Ag alloy, Cu, and Cu alloy is embedded in a base material having spring elasticity, has an arc-shaped A shape.
g, Ag alloy, Cu, and a commutator piece having an electric sliding contact material made of any one of a Cu alloy and a brush or / and an electric sliding of the commutator piece in an electric sliding contact portion that performs sliding energization. One or two metal elements selected from the group IIIa and IIIb elements of the periodic table whose standard free energy of oxide formation is smaller than that of the electric sliding contact material Ag, Ag-based alloy, Cu, Cu-based alloy as the contact material An electric sliding contact material in which the metal oxide of the implanted element is dispersed in the contact material by the direct ion implantation method and then oxidized after the implantation. 3. The method according to claim 1, wherein the metal element injected into the sliding contact material is A
l, Y, Ge or one or more of them, and the injection amount is 1
The electric sliding contact material according to claim 1 or 2, wherein the material has a dose of 10 ¹⁶ to 1 10 ²⁰ (ions / cm ² ). 4. The electric sliding contact material according to claim 1, wherein an injection depth of the metal element injected into the sliding contact material is 0.1 μm to 100 μm. 5. The sliding contact material of the brush and / or the commutator piece is made of Au, Ag, Pd, Pt, Ru, Rh, C
The electric sliding contact material according to claim 1 or 2, wherein the material is one or more alloys selected from u, Ir, In, Ni, Sn, Zn, Ru, and Be. 6. The dispersed metal oxide has a particle size of 10 to 50.
3. The electric sliding contact material according to claim 2, which has a thickness of 0 nm. 7. A DC motor provided with the electric sliding contact material according to claim 1.