【発明の詳細な説明】[Detailed description of the invention]
本発明は、直流小型モータの整流子用摺動接点
材料（以下「摺動接点材料」という。）の改良に
関する。
従来より摺動接点材料の一つとして硬さに優れ
たAg―Cu合金が用いられてきたが、Ag―Cu合
金の摺動接点材料は酸化し易くて摩耗し易く接触
抵抗が高く不安定になるという欠点があり、従つ
てこの摺動接点材料で小型モータの整流子の外周
の接点片を製作して使用した場合には刷子接点と
の接触抵抗が変化し、整流子の回転速度が大きく
ばらついて不安定なものとなつていた。
本発明は、かかる欠点を解消すべくなされたも
のであり、Ag―Cu合金の酸化を抑制し、硬さを
維持しつつ耐摩耗性を向上させ、しかも接触抵抗
を低く安定させた摺動接点材料を提供せんとする
ものである。
本発明の摺動接点材料は、Cu5〜10重量％、
Tl0.5〜２重量％及び残部Agの銀合金から成るも
のである。
かかる本発明の摺動接点材料に於いて、Ag中
に５〜10重量％（以下、「ｗ／ｏ」という。）の
Cuを添加した以外にTlを0.5〜2w／ｏ添加するの
は、TlがCuよりも酸化し易いので、Tlの添加さ
れた材料より成る整流子の外周の接点片はAg―
Cu合金での酸化が抑制され、つまり前記の添加
された元素の酸化により、CuOの生成が抑制さ
れ、Ag―Cu合金の有する硬さが維持されて耐消
耗性が向上すると共に接触抵抗が低く安定するか
らであり、0.5w／ｏ未満ではAg―Cu合金での酸
化が抑制されず、つまりCuOが生成されて接触抵
抗が高く不安定になり、2w／ｏを超えるとAg―
Cu合金の電気抵抗が高くなるので、結局0.5〜
2w／ｏの添加が必要である。
次に本発明による摺動接点材料と従来の摺動接
点材料にて作つた小型モータの整流子の接点片に
ついて説明する。
後記の表の右欄に示す成分組成の本発明の実施
例である摺動接点材料と従来例の摺動接点材料に
て、図面に示す如く小型モータの直径６mm、長さ
９mmの整流子１の外周に厚さ0.2mmの接点片１ａ
が形成され、この接点片１ａの外周面の上下に、
Au―Ag―Cu―Pt合金より成る直径0.25mm、長さ
10mmの３本の刷子線材２を有する刷子接点３を相
対向するように摺動させて、後記の試験条件にて
整流子１の回転試験を行い、接点片１ａの消耗量
と整流子１の回転数のばらつきを測定した処、後
記の表の右欄に示すような結果を得た。
試験条件
電 圧 ：12V
電 流 ：直流60mA
整流子の回転数 ：2800回転／分
整流子の回転時間：500時間
刷子接点の接触力：５ｇ／３本
The present invention relates to improvements in sliding contact materials for commutators of small DC motors (hereinafter referred to as "sliding contact materials"). Ag-Cu alloy, which has excellent hardness, has traditionally been used as a sliding contact material, but the Ag-Cu alloy sliding contact material is easily oxidized and worn, and has high contact resistance and is unstable. Therefore, if this sliding contact material is used to manufacture and use a contact piece around the commutator of a small motor, the contact resistance with the brush contact will change, and the rotation speed of the commutator will increase. It had become scattered and unstable. The present invention was made to eliminate these drawbacks, and provides a sliding contact that suppresses oxidation of the Ag-Cu alloy, maintains hardness and improves wear resistance, and has low and stable contact resistance. The aim is to provide materials. The sliding contact material of the present invention contains Cu5 to 10% by weight,
It consists of a silver alloy of 0.5 to 2% by weight of Tl and the balance being Ag. In the sliding contact material of the present invention, 5 to 10% by weight (hereinafter referred to as "w/o") of Ag is added to the sliding contact material of the present invention.
The reason for adding 0.5 to 2 w/o of Tl in addition to Cu is that Tl is more easily oxidized than Cu, so the contact piece on the outer periphery of the commutator made of material to which Tl is added is Ag-
Oxidation in the Cu alloy is suppressed, that is, due to the oxidation of the added elements mentioned above, the formation of CuO is suppressed, the hardness of the Ag-Cu alloy is maintained, the wear resistance is improved, and the contact resistance is low. If it is less than 0.5w/o, oxidation in the Ag-Cu alloy is not suppressed, which means that CuO is generated, resulting in high contact resistance and instability.If it exceeds 2w/o, the Ag-Cu alloy becomes unstable.
As the electrical resistance of Cu alloy increases, it ends up being 0.5 ~
It is necessary to add 2w/o. Next, a contact piece for a commutator of a small motor made of a sliding contact material according to the present invention and a conventional sliding contact material will be explained. A commutator 1 of a small motor with a diameter of 6 mm and a length of 9 mm as shown in the drawings was prepared using the sliding contact material according to the embodiment of the present invention and the conventional sliding contact material having the compositions shown in the right column of the table below. A contact piece 1a with a thickness of 0.2 mm is placed on the outer periphery of the
are formed on the top and bottom of the outer peripheral surface of this contact piece 1a,
Made of Au-Ag-Cu-Pt alloy, diameter 0.25mm, length
A rotation test was performed on the commutator 1 under the test conditions described below by sliding the brush contacts 3 having three 10 mm brush wires 2 so as to face each other, and the wear amount of the contact piece 1a and the commutator 1 were When we measured the variation in rotational speed, we obtained the results shown in the right column of the table below. Test conditions Voltage: 12V Current: DC 60mA Commutator rotation speed: 2800 rotations/min Commutator rotation time: 500 hours Contact force of brush contacts: 5g/3 pieces
【表】
前記の表で明らかなように従来例の接点片の消
耗量は３〜5.5μmであつたのに対し、実施例の接
点片の消耗量は2.0〜4.0μmで減少していて耐消耗
性に優れていることが判る。また従来例の接点片
を有する整流子の回転数のばらつきは7.5〜10％
であつたのに対し、実施例の接点片を有する整流
子の回転数のばらつきは3.5〜5.0％で著しく減少
していることが判る。これはひとえに実施例の接
点片がAg―Cu合金での酸化が抑制されて接触抵
抗が低く安定しているからに他ならない。
以上詳記した通り本発明の摺動接点材料は、
Ag―Cu合金の酸化が抑制され、硬さが維持され
ているので、これにより作つた小型モータの整流
子の接点片の耐消耗性は向上するものである。ま
たAg―Cu合金の酸化が抑制されて接触抵抗が低
く安定しているので、小型のモータの整流子の回
転数のばらつきが大幅に減少する等の優れた効果
がある。[Table] As is clear from the above table, the amount of wear of the contact piece of the conventional example was 3 to 5.5 μm, while the amount of wear of the contact piece of the example was reduced to 2.0 to 4.0 μm, indicating that the contact piece of the example had a reduced amount of wear of 2.0 to 4.0 μm. It can be seen that it has excellent consumability. In addition, the variation in rotation speed of the commutator with conventional contact pieces is 7.5 to 10%.
On the other hand, it can be seen that the variation in the rotation speed of the commutator having the contact piece of the example is significantly reduced to 3.5 to 5.0%. This is simply because the contact piece of the example has a low and stable contact resistance due to the suppressed oxidation of the Ag--Cu alloy. As detailed above, the sliding contact material of the present invention is
Since the oxidation of the Ag-Cu alloy is suppressed and its hardness is maintained, the wear resistance of the commutator contact pieces of small motors made using this alloy is improved. Furthermore, since the oxidation of the Ag--Cu alloy is suppressed and the contact resistance is low and stable, it has excellent effects such as greatly reducing variations in the rotation speed of the commutator of small motors.
【図面の簡単な説明】[Brief explanation of drawings]
図は小型モータの整流子と刷子接点との接触状
態を示す斜視図である。
１……整流子、１ａ……接点片、２……刷子線
材、３……刷子接点。
The figure is a perspective view showing the state of contact between the commutator and brush contacts of a small motor. 1...Commutator, 1a...Contact piece, 2...Brush wire, 3...Brush contact.