WO2005096474A1

WO2005096474A1 - Electric contact mechanism for small motor

Info

Publication number: WO2005096474A1
Application number: PCT/JP2005/006251
Authority: WO
Inventors: Daichi Watanabe; Kazuya Nakamura
Original assignee: Namiki Seimitsu Houseki Kabusikikaisha
Priority date: 2004-04-02
Filing date: 2005-03-31
Publication date: 2005-10-13
Also published as: JP2005295747A

Abstract

[PROBLEMS] To provide an electric contact mechanism for a small motor in which durability of electric contacts can be improved by reducing mechanical abrasion and electrical abrasion. [MEANS FOR SOLVING PROBLEMS] In an electric contact mechanism for a small motor especially for one having a relatively high driving voltage or power consumption, carbonaceous materials are employed as the contact material. The carbonaceous materials are bundled together into a brush shape having lengths ranging from several hundreds μm to several mm. Consequently, mechanical sliding abrasion can be reduced, and furthermore generation of arc can be suppressed, thereby reducing electrical abrasion (electrical corrosion).

Description

Specification

Electric contact mechanism for small motor

Technical field

The present invention relates to an electric contact mechanism for a small motor! The present invention relates to an electric contact mechanism capable of reducing mechanical wear and electric wear.

Background art

Conventionally, as a contact material of a small motor, particularly a contact material of a brush, a pressurized and fired body mainly composed of a plurality of precious metal multi-element alloys, graphite and Cu has been widely used. These materials are generally selected according to the motor drive voltage, power consumption, and the like. The material of the commutator that slides in contact is appropriately selected depending on the brush material or driving conditions. However, the electric contacts of a small motor are slid when the motor is driven, so that mechanical sliding wear occurs. Figures 4 and 5 show the means to improve the durability of electrical contacts by reducing this mechanical sliding wear.

[0003] In Fig. 4, at least the outermost layer contains conductive carbon nanofibers or carbon fibers composed of carbon nanotubes, and is brushed under pressure and fired (further preferred with the inclusion of Kurofune), and is electrically operated. It has been proposed to improve conductivity, reduce mechanical sliding wear and contact resistance between commutators, and improve corrosion resistance due to the improvement of brush surface roughness by filling carbon nanofibres or carbon nanotubes between material particles. RU (Patent Document 1).

[0004] In FIG. 5, the contact is formed by a plurality of carbon nanotube bundles having a plurality of carbon nanotubes whose one end is fixed to the movable body and the other free end is opposed to the electrode. It has been proposed that the mechanical sliding wear of the contact can be reduced, the corrosion resistance can be improved, and the elasticity can be adjusted! (Patent Document 2).

Patent Document 1: JP 2004-033293

Patent-Document 2: JP 2003-284304

Disclosure of the invention

Problems the invention is trying to solve [0005] In general, when power consumption is relatively large, electric wear (electrolytic corrosion) with a large arc energy tends to be dominant. The arc that causes this electrical wear occurs when the brush commutator is electrically disconnected. An arc is generated when the residual current Ie that remains without being fully rectified when the electrical connection is interrupted exceeds a minimum arc current Imin that is a material intrinsic value. Arc energy Ea, which is considered to be correlated with brush wear, is expressed as

[0006] (number 1)

Ea = Lc (Ie —Imin) / 2

[0007] is shown. It is believed that the brush energy due to electrical wear is suppressed, especially as the arc energy decreases as the residual current decreases.

[0008] In order to reduce the residual current, it is desirable that the two contacts always and stably contact each other as widely as possible when energizing the brush commutator.

[0009] However, neither of Patent Documents 1 and 2 mentioned above has been improved with respect to this electrical wear (electrolytic corrosion). Patent Document 1 has a structure in which a solid carbon brush is filled with carbon nanotubes, so that the shape is not different from that of a conventional carbon brush. That is, since the contact material cannot follow the commutator, the arc is apt to fly. Further, in Patent Document 2, a carbon nanotube is formed in a cylindrical shape by a single crystal which has only a covalent bond of a carbon atom. Since the length is several hundred meters at a maximum, the carbon nanotube is always in contact with a rotating commutator. It is difficult. In addition, it has a structure that can change the rigidity of the whole carbon nanotube bundle by changing the density, while the overall length for a nano-order diameter is several tens of meters to several hundreds of μm. It is not possible to say that sufficient consideration is given to unexpected bending near the free end of the carbon nanotube, and as a result, the features of orientation cannot be fully utilized. It will be connected.

[0010] When these electric contact mechanisms are mounted on a small motor, the effect of electric wear on the contact portions becomes more remarkable as the power consumption increases. Therefore, the contact portion is likely to be fused or burnt out, and the life of the small motor is often reached.

The present invention relates to a small motor, particularly a small motor having a large driving voltage or large power consumption. The purpose is to obtain a material 'form suitable for electrical contacts and a structure that suppresses the arc itself during motor operation.

Means for solving the problem

[0012] The present inventors formed an electric contact mechanism that made a carbon-based material into a fibrous shape and oriented substantially perpendicular to the elastic material fixing surface as a brush in which a contact material was fixed to a conductive elastic material. It was found that the problem could be solved by doing so. The electric contact mechanism for a small motor according to the present invention is characterized by having a structure that suppresses the generation of an arc that is formed by a strong force and has excellent wear resistance and heat resistance.

[0013] The carbon-based material used for the contact material in the present invention is graphite fiber, CNT (SWNT, MWNT), peapod nanotube, CNF (Carbon Nano Fiber), FNW, fullerene chenole tube, carbon monorefass tube (Glass carbon tube). Since these carbon-based materials have high heat resistance, the brush sliding surface becomes brittle due to frictional heat generated during mechanical sliding, heat related to arc energy, or Joule heat due to contact resistance between brush commutators. Can be suppressed. In addition, since the heat conductivity is good, various kinds of heat can be efficiently dispersed from the brush-commutator sliding surface, and the coefficient of friction with the partner material is small, so that heat generation can be suppressed.

[0014] The invention according to claim 1 is a small motor in which a brush in which a contact material is fixed to a conductive elastic material slides in contact with a rectifier and commutates to an armature connected to a commutator. In the electrical contact mechanism for use, a carbon-based material is used for the contact material, and the carbon-based material is entangled with each other to form a fibrous shape, and the fibrous carbon-based material is attached to the elastic material fixing surface of the contact material. On the other hand, an electric contact mechanism for a small motor characterized by being oriented substantially vertically.

[0015] Since the carbon-based material has anisotropy in which the electrical conductivity in the interlayer direction of the crystal is significantly smaller than the electrical conductivity in the plane direction of the crystal layer, the carbon-based material must be oriented substantially perpendicular to the contact material fixing surface. Although the effective electrical conductivity can be maintained, the carbon fiber is entangled in a fiber shape. An electric contact mechanism for a small motor having such a contact material can be formed.

[0016] The invention according to claim 2 is the electric contact mechanism for a small motor according to claim 1, wherein the carbon-based material of the contact material is formed in a fibrous shape, so that the length is several hundred meters to several hundreds. mm, which is an electrical contact mechanism for small motors.

[0017] In the electric contact mechanism for a small motor, the length of the carbon-based material having a fibrous shape as a contact material of the brush is from several hundred m to several mm, so that the end of the conductive elastic material is formed. A brush fixed in a brush-like form. For this reason, this contact material is excellent in corrosion resistance and flexible, and is suitable for commutator vibration generated due to commutator roundness, eccentricity, rotation speed, etc. However, the contact material reliably follows the curved surface of the commutator, and the brush and the commutator can always make stable contact over a wide range.

[0018] The invention according to claim 3 is the electrical contact mechanism for a small motor according to claim 1 or claim 2, wherein the carbon-based material is SWNT (Single Wall Nano Tube), MWNT (Multi Wall Nano Tube), FNW. (Fullerene Nano Whisker), or a derivative thereof, is an electrical contact mechanism for small motors, characterized by having a contact material formed into a fibrous shape by entanglement of at least one or more molecules of each other. .

[0019] As the carbon-based material, at least one of CNT, FNW, or a derivative thereof (a chemical derivative such as a substituent-added substance, or a physical derivative such as a fullerene tube or a carbon amorphous tube (glass-carbon tube)). By using these molecules, the heat dissipation characteristics due to heat conduction show values comparable to diamond, the current capacity shows a maximum of 10 ⁹ AZcm ² , the electrical conductivity shows a maximum of 10 ^_4 Ω Ζ «η, the driving voltage, Or, an ideal contact material can be formed for a small motor with relatively large power consumption.

[0020] The invention according to claim 4 is the electrical contact mechanism for a small motor according to claim 1 or claim 2, wherein at least one of SWNT, MWNT, FNW, or a derivative thereof is used as the carbon-based material. A small-sized motor having a contact material in which molecules are entangled with each other in a mesh and are oriented in substantially one direction, are formed in a thin sheet shape, and are laminated so that the orientation direction is substantially constant. Electrical contact mechanism.

[0021] In the present embodiment in which the carbon-based material is entangled and oriented in a mesh shape and laminated in the form of a thin sheet, the electric contact mechanism for a small motor is most easily produced even when the raw material is in a cotton-like state. This is advantageous in terms of productivity. In addition, because of the thin sheet shape, unexpected bending occurs while maintaining the flexibility to reliably follow the curved surface of the commutator. The most frequent occurrence is that it is possible to form a contact mechanism for a small motor having a contact material that can reliably obtain an orientation effect.

[0022] The invention according to claim 5 provides the electrical contact mechanism for a small motor according to claims 1 and 2, wherein at least one of SWNT, MWNT, FNW, or a derivative thereof is used as the carbon-based material. A composite of a fibrous contact material, in which molecules are entangled with each other, and a contact material, which is entangled with each other in a mesh and formed in a thin sheet shape, and is substantially perpendicular to the contact material fixing surface. This is an electrical contact mechanism for a small motor, characterized by having a contact material oriented in a direction.

[0023] The present invention is not limited to one of the structure of the contact material formed of a carbon-based material in a fibrous form and the structure of the contact material formed of a thin sheet, and may be a composite of these structures. There is no problem at all.

[0024] The invention according to claim 6 is the electric contact mechanism for a small motor according to claims 3 to 5, wherein SWNT, MWNT, FNW, or a derivative thereof includes a spherical fullerene or a metal-containing spherical fullerene. This is the electrical contact mechanism for small motors.

[0025] By including the spherical fullerene in SWNT, MWNT, FNW, or a derivative thereof, electric conductivity can be improved. Furthermore, it is more preferable that the spherical fullerenes are encapsulated after they are superposed, because electrons released during polymerization impart conductivity and electric conductivity is improved. It is more preferable to include a spherical fullerene containing a metal having electric conductivity because conduction electrons of metal atoms improve electric conductivity.

[0026] The invention according to claim 7 is the electric contact mechanism for small motor according to any one of claims 1 to 6, characterized in that a metal is interposed in a carbon-based material. is there.

[0027] The present invention has one or both of the interposition of a metal on the surface of a carbon-based material and the interposition of inclusion of a metal in the carbon-based material. As a result, a contact material having both the high electrical conductivity of a metal and the heat resistance, heat dissipation, and arc resistance of a carbon-based material can be realized. In addition, if metal is included in carbon-based material, In such a case, the conduction electrons of the metal atoms produce a further effect of improving the electrical conductivity of the carbon-based material. When importance is placed on electrical conductivity, it is preferable to use a metal based on Au, Ag, Cu, or Al, or an alloy containing them.When importance is placed on thermal properties / arc resistance, Refractory metals based on refractory elements such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Pd, Pt, Fe, Co, Ni, or alloys containing them It is preferred that

[0028] The invention according to claim 8 is the electrical contact mechanism for a small motor according to claims 1 to 7, wherein the carbon-based material and the elastic material or the carbon-based materials are electrically joined by using a metal. This is an electrical contact mechanism for a small motor.

[0029] Since contact resistance always exists between the contact points of the materials, the resistance of the contact material on the visual acuity varies significantly depending on the contact state between the materials. In the present invention, a metal-carbon compound is formed between the carbon-based material and the contact point or between the carbon-based materials to thereby electrically connect them. By using a metal-carbon compound having good electrical conductivity as the bonding material, the contact resistance is reduced. Further, when the contact area is increased by burying the carbon-based material in the metal, the contact resistance is reduced, and it becomes possible to more smoothly transfer electrons. In particular, a metal based on an element compatible with carbon, such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, or Si, or an alloy containing them is preferable.

[0030] As described above, by applying the electric contact mechanism for a small motor of the present invention, unexpected bending that occurs near the free end of the carbon-based material is bound by the carbon-based material, and the orientation effect can be reliably obtained. In addition, the brush force having flexibility has the ability to reliably follow the curved surface of the commutator, and since the brush and the commutator are in stable contact over a wide range, the occurrence of arc is suppressed, electrical wear is reduced, and mechanical sliding is achieved. In addition to suppressing dynamic wear, improving heat resistance and corrosion resistance, it is possible to form an electric contact mechanism for a small motor having a contact material excellent in electric wear (electrolytic corrosion) and electric conductivity.

The invention's effect

The present invention relates to a brush structure of an electric contact of a small motor, particularly a small motor having relatively large driving voltage or power consumption, wherein a fibrous carbon-based material is used for the material, and the fibrous carbon-based material is used. Is formed with a length of several hundred m to several mm, and the form is brush Since the brush structure is in the form of a brush, it is possible to reduce mechanical sliding wear and to suppress the occurrence of arcs, thereby reducing electrical wear.

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

FIG. 1 shows a schematic view of a contact member 1 of a contact mechanism for a small motor according to a first embodiment. The contact material 1 is formed of a carbon-based material in a fiber shape, has a length L of several hundreds to several mm, and is oriented substantially perpendicular to the contact material fixing surface.

Next, a method for producing the fibrous carbon-based material according to the first embodiment will be described. First, various carbon-based materials entangled in a flocculent form are poured into a glass container containing an organic solvent such as a polymer and a solvent appropriately selected, and mixed with a mixed liquid in which the carbon-based material is dispersed in an organic solvent. did. When the carbon-based material was dispersed in a liquid, the carbon-based material was sufficiently stirred or refined so that the carbon-based material was not unevenly distributed.

Then, the obtained mixed liquid is poured into a nozzle having a tip hole diameter of 10 μm and a tip length of about 5 mm, and the inside of the nozzle is pressurized and ejected, whereby fibrous carbon oriented in the ejection direction is injected. A base material was obtained. The fibrous carbon-based material was oriented in a direction substantially perpendicular to a surface of 2 mm (D) X O. 1 mm (W), and the length was adjusted to 0.3 mm. The remaining organic solvent was removed using a solvent.

(Second Embodiment)

FIG. 2 shows a contact material 3 of a contact mechanism for a small motor according to a second embodiment. The contact material 3 is made of a carbon-based material entangled with each other to form a thin sheet. The contact material 3 is formed by stacking the thin sheet-like carbon-based materials and orienting the carbon material substantially perpendicularly to the contact material fixing surface.

Next, a method for producing the fibrous carbon-based material of the second embodiment will be described. First, various carbon-based materials entangled in a flocculent form are poured into a glass container containing an organic solvent such as a polymer and a solvent appropriately selected, and mixed with a mixed liquid in which the carbon-based material is dispersed in an organic solvent. did. When the carbon-based material was dispersed in a liquid, the carbon-based material was sufficiently stirred or refined so that the carbon-based material was not unevenly distributed.

[0037] Then, the obtained mixed liquid was poured onto a filter having a pore size of 1 µm, and filtration was performed. The deposit on the filter was peeled off to form a thin sheet carbonaceous material. Furthermore, by applying a tensile stress to the formed thin sheet carbonaceous material in a uniaxial direction, a sheet oriented in the tensile direction could be obtained. These were oriented in a direction substantially perpendicular to the contact material fixing surface, and were laminated to obtain the contact material 3 having a rectangular parallelepiped shape of 2 mm (D) X O. lmm (W) X O. 3 mm (H). The remaining organic solvent was removed using a solvent.

[0038] A metal carbon compound was formed and fixed between the contact materials 1 and 3 obtained by the above-described production method and the elastic materials 2 and 4 having conductivity to obtain a brush shape. Using a tester, energization between the contact material and the elastic material was confirmed.

[0039] For example, when a conventional noble metal brush or carbon brush is mounted on a small motor, and a life test is performed with a driving voltage of 12V and a driving mode of continuous no-load rotation, a small motor with a conventional noble metal brush is mounted. Motor burns severely and stops at 80 ~: L00 hours

[0040] In addition, a small motor equipped with a carbon brush causes a contact failure due to wear of the brush, and stops in about 90 hours. Conventionally, carbon brushes have a large volume that easily causes wear during sliding to compensate for the effects of wear and ensure a long life.However, as the size becomes smaller, the volume that can be secured is reduced. As a result, the life of small motors has been significantly reduced.

[0041] On the other hand, by using the fibrous carbon-based material of the present invention as a contact material, a life improvement of several times to several tens of times compared to a conventional electric contact mechanism can be expected. This uses a carbon-based material for the contact material, so it can withstand high power consumption and has a flexible structure, so there is little mechanical wear and the contact material follows the commutator reliably. This is because the occurrence of arcs was suppressed and electrical wear was reduced.

[0042] As described above, the present invention is suitable for a small motor, particularly a small motor having a large driving voltage or power consumption, in the present invention, and suppresses the generation of an arc itself when the motor is driven. It is a very effective structure.

[0043] By using the electric contact mechanism having the above structure, it is possible to suppress not only mechanical sliding wear and improvement of corrosion resistance but also electric wear, that is, generation of an arc which directly causes electrolytic corrosion. It becomes possible. To ensure the above effects, the length must be several hundred It is practically more preferable that it is from μm to several mm.

Industrial applicability

The present invention provides only mechanical sliding wear by using a fibrous carbon-based material that is entangled, oriented, and configured with each other as a brush contact material in an electric contact mechanism for a small motor. The electrical abrasion is reduced, and the durability of the electrical contacts can be improved.

Brief Description of Drawings

FIG. 1 is a schematic view showing a first embodiment of the present invention.

FIG. 2 is a schematic view showing a second embodiment of the present invention.

[Fig.3] Enlarged view of part a in Fig.1

[FIG. 4] A schematic diagram of a cross section of a conventional brush in Patent Document 1.

FIG. 5 is a schematic view showing a schematic configuration of an electric contact device in which a conventional contact is incorporated in Patent Document 2.

Explanation of symbols

[0046] 1, 3 contact materials

2, 4 Elastic material with conductivity

Claims

The scope of the claims

[1] An electric contact mechanism for a small motor in which a brush in which a contact material is fixed to a conductive elastic material slides in contact with a commutator and commutates to an armature connected to the commutator.

A carbon-based material is used as the contact material, and the carbon-based material is entangled with each other to form a fiber, and the fibrous carbon-based material is substantially perpendicular to the contact material fixing surface of the elastic material. An electrical contact mechanism for small motors characterized by being oriented.

[2] The electrical contact mechanism for a small motor according to claim 1, wherein the carbon-based material of the contact material is formed in a fibrous shape to have a length of several hundred m to several mm. Electric contact mechanism for motor.

[3] The electrical contact mechanism for a small motor according to claim 1 or 2, wherein the carbon-based material is SWNT (Single Wall Nano Tube), MWNT (Multi Wall Nano Tube), FNW (Fullerene Nano Whisker), or An electrical contact mechanism for a small motor, comprising: a contact material formed into a fibrous shape by entanglement of at least one kind of molecule among the derivatives.

[4] The electrical contact mechanism for a small motor according to claim 1 or 2, wherein at least one molecule of SWNT, MWNT, FNW, or a derivative thereof as a carbon-based material is entangled with each other in a mesh shape. An electric contact mechanism for a small motor, characterized by having contact materials which are combined and oriented in substantially one direction, are formed into a thin sheet shape, and are laminated so that the orientation direction is substantially constant.

[5] The electrical contact mechanism for a small motor according to claim 1 or 2, wherein at least one molecule of SWNT, MWNT, FNW, or a derivative thereof as a carbon-based material is entangled with each other. And a contact material that is entangled with each other in a mesh form, is formed into a thin sheet shape, and is oriented substantially perpendicular to the contact material fixing surface. Electrical contact mechanism for small motors.

[6] The electrical contact mechanism for a small motor according to any one of claims 1 to 5, further comprising SWNT, MWNT, F NW, or a derivative fullerene or metal-containing spherical fullerene thereof. Electric contact mechanism for small motors.

[7] The electrical contact mechanism for a small motor according to any one of claims 1 to 6, wherein a metal is used for the carbon-based material. Electrical contact mechanism for small motors, characterized by being interposed.

8. The electric contact mechanism for a small motor according to claim 1, wherein the carbon-based material and the elastic material, or the carbon-based materials are electrically connected to each other by using a metal. Electric contact mechanism.