JP2005295747A - Electric contact mechanism for small motors - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric contact mechanism for a small motor in which mechanical wear and electric wear are reduced and durability of an electric contact can be improved.
In an electric contact mechanism of a small motor, in particular, a small motor with relatively large driving voltage or power consumption, a carbon-based material is used as the material of the contact material, and the carbon-based materials are entangled with each other, and the length The thickness is set to several hundreds μm to several mm, and the form is a brush shape to reduce mechanical sliding wear, further suppress arc generation, and reduce electrical wear (electric corrosion). It becomes possible to do.
[Selection] Figure 1

Description

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

  Conventionally, as an electrical contact of a small motor, particularly a contact material of a brush, a plurality of precious metal multi-component alloys, a pressure / fired body mainly composed of graphite and Cu, and the like are widely used. These materials are generally selected depending on the motor driving voltage, power consumption, and the like. The commutator material that contacts and slides is appropriately selected depending on the brush material or driving conditions. However, since the electric contact of the small motor slides when the motor is driven, mechanical sliding wear occurs. 4 and 5 are shown as means for improving the durability of the electrical contact by reducing the mechanical sliding wear.

  In FIG. 4, at least the outermost layer contains carbon nanofibers or carbon fibers made of carbon nanotubes that are conductive, and is a pressed and fired brush (more preferably containing graphite). There has been proposed reduction of mechanical sliding wear, contact resistance between commutators, and improvement of corrosion resistance due to improvement of brush surface roughness by filling carbon nanofibers or carbon nanotubes between particles (Patent Document 1).

In FIG. 5, the contact is formed of a carbon nanotube bundle composed of a plurality of carbon nanotubes, one end of which is fixed to the movable body and the other end of the contact is opposed to the electrode. It has been proposed that dynamic wear can be reduced, corrosion resistance can be improved, and elasticity can be adjusted (Patent Document 2).
JP2004-032963 JP 2003-284304 A

  Generally, when power consumption is relatively large, arc energy is large and electric wear (electric corrosion) tends to be dominant. This arc that causes electrical wear occurs when the brush-commutator electrical connection is interrupted. An arc is generated when the residual current Ie remaining without being rectified when the electrical connection is cut exceeds the minimum arc current Imin, which is a material specific value. Further, the arc energy Ea, which is considered to have a correlation with the brush wear, is expressed as follows:

(Equation 1)
Ea = Lc (Ie ² −Imin ² ) / 2

  It is indicated by. As the residual current decreases, the arc energy decreases, and it is considered that brush wear due to electrical wear is particularly suppressed.

  In order to reduce the residual current, it is desirable that the two are in contact with each other stably in a wide range as much as possible during energization between the brush and the commutator.

  However, neither of the above-mentioned Patent Documents 1 and 2 has been improved against this electric wear (electric corrosion). In patent document 1, since it is the structure which fills a solid carbon brush with a carbon nanotube, a shape is not different from the conventional carbon brush. That is, since the contact material cannot follow the commutator, it cannot be denied that the arc is easy to fly. In Patent Document 2, the carbon nanotubes are formed of a single crystal consisting of only covalent bonds of carbon atoms and are formed into a cylindrical shape. However, since the length is several hundred μm at the maximum, the carbon nanotubes are always in contact with the rotating commutator. Is difficult. Further, it has a structure that can change the rigidity of the entire bundle of carbon nanotubes by changing the density, but it tends to occur when the overall length with respect to the nano-order diameter has a high aspect ratio of several tens to several hundreds of micrometers. It cannot be said that sufficient consideration is given to the unexpected bending in the vicinity of the free end of the carbon nanotube, and as a result, it becomes impossible to make full use of the features of orientation.

  When these electric contact mechanisms are mounted on a small motor, the influence of electrical wear becomes more noticeable as the power consumption of the contact portion increases. Therefore, this contact portion often causes fusion, burnout, etc., and the life as a small motor is often reached.

  The present invention provides a material and form suitable for an electrical contact of a small motor, in particular, a small motor having a large driving voltage or power consumption, and a structure that suppresses the occurrence of arc itself during motor operation.

  As a brush in which a contact material is fixed to a conductive elastic material, the present inventors form a carbon-based material into a fiber and form an electrical contact mechanism that is oriented substantially perpendicular to the elastic material fixing surface. We found that it was possible to solve the problem. The electric contact mechanism for a small motor according to the present invention is characterized by having not only excellent wear resistance and heat resistance but also a structure that suppresses the occurrence of arc itself.

  The carbon-based material used for the contact material in the present invention is a generic name for graphite fiber body, CNT (SWNT, MWNT), peapod nanotube, CNF (Carbon Nano Fiber), FNW, fullerene shell tube, and carbon amorphous tube (glassy carbon tube). It is a thing. Since these carbon-based materials have high heat resistance, the brush sliding surface is weakened by frictional heat generated during mechanical sliding, heat generation related to arc energy, or Joule heat due to contact resistance between the brush and commutator. Can be suppressed. Moreover, since heat conductivity is favorable, various heat can be efficiently disperse | distributed from a brush-commutator sliding surface, and since the friction coefficient with respect to a counterpart material is also small, heat generation can be suppressed.

  According to the first aspect of the present invention, there is provided an electric contact mechanism for a small motor in which a brush in which a contact material is fixed to a conductive elastic material abuts and slides on a commutator and commutates to an armature connected to the commutator. In the above, a carbon-based material is used for the contact material, and the carbon-based materials are 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. This is an electric contact mechanism for a small motor characterized by being oriented in the direction.

  Since carbon-based materials have anisotropy in which the electrical conductivity in the crystal layer direction is significantly smaller than the electrical conductivity in the plane direction of the crystal layer, it is effective by being oriented substantially perpendicular to the contact material fixing surface. It is possible to maintain a high electrical conductivity, but since it is entangled in a fibrous form, a contact material that can be surely obtained an orientation effect by bundling the unexpected bending near the free end of the carbon-based material with the carbon-based material. An electric contact mechanism for a small motor can be formed.

  According to a second aspect of the present invention, in the electric contact mechanism for a small motor according to the first aspect, the carbon-based material of the contact material is formed into a fiber shape, so that the length is several hundreds μm to several mm. This is a featured electric contact mechanism for a small motor.

  As a brush contact material in an electric contact mechanism for a small motor, the length of a carbon-based material that forms a fiber is several hundred μm to several mm, and is fixed to one end of a conductive elastic material in a brush shape. Brushes can be constructed. For this reason, this contact material is excellent in corrosion resistance and rich in flexibility, and when the commutator vibrations occur in relation to the roundness, eccentricity, rotation speed, etc. of the commutator when passing between the commutator pieces of the brush. However, the contact material reliably follows the curved surface of the commutator, so that the brush and the commutator can always stably contact in a wide range.

  According to a third aspect of the present invention, there is provided an electric contact mechanism for a small motor according to the first or second aspect of the present invention. Or an electrical contact mechanism for a small motor, characterized in that it has a contact material formed into a fibrous shape by entanglement of at least one kind of molecules among them.

As a carbon-based material, at least one molecule of CNT, FNW, or a derivative thereof (a chemical derivative such as a substituent group-provided substance or a physical derivative such as a fullerene shell tube or a carbon amorphous tube (glassy carbon tube)) When used, the heat dissipation characteristics due to heat conduction show values comparable to diamond, the current capacity is up to 10 ⁹ A / cm ² , the electric conductivity is up to 10 ⁻⁴ Ω / cm, and the drive voltage or power consumption An ideal contact material can be formed in a small motor having a relatively large size.

  According to a fourth aspect of the present invention, in the electric contact mechanism for a small motor according to the first or second aspect, at least one or more molecules of SWNT, MWNT, FNW, or a derivative thereof as a carbon-based material are mesh-like. An electric contact mechanism for a small motor, characterized in that it has a contact material that is intertwined with each other and oriented in approximately one direction, is formed in a thin sheet shape, and is laminated so that the orientation direction is substantially constant. is there.

  In the embodiment of the present invention in which carbon materials are entangled in a mesh, oriented, and laminated in the form of a thin sheet, it becomes possible to produce the electric contact mechanism for a small motor most easily even if the raw material is in a cotton-like state. This is advantageous in terms of productivity. In addition, because it is a thin sheet, it forms a contact mechanism for small motors with contact material that is most unlikely to cause unexpected bending while maintaining the flexibility to reliably follow the curved surface of the commutator. it can.

  According to a fifth aspect of the present invention, in the electric contact mechanism for a small motor according to the first or second aspect, at least one molecule of SWNT, MWNT, FNW, or a derivative thereof is entangled as a carbon-based material. The contact material formed in a fibrous shape and the contact material that is entangled with each other in a mesh shape and formed in a thin sheet shape, and is oriented substantially perpendicular to the contact material fixing surface It is an electric contact mechanism for small motors characterized by having.

  The present invention is not limited to the structure of any one of the contact material in which the carbon-based material is formed in a fiber shape and the contact material formed in a thin sheet shape, and there is no problem even if it is a composite of these structures. .

  A sixth aspect of the present invention is the electric contact mechanism for a small motor according to the third to fifth aspects, wherein the SWNT, MWNT, FNW, or a derivative thereof includes a spherical fullerene or a metal-encapsulated spherical fullerene. This is an electric contact mechanism for a small motor.

  The electrical conductivity can be improved by encapsulating the spherical fullerene in SWNT, MWNT, FNW, or a derivative thereof. Furthermore, it is more preferable that the spherical fullerenes are encapsulated and then encapsulated, so that electrons released during polymerization give conductivity and electrical conductivity is improved. In addition, since the spherical fullerene in which the metal having electric conductivity is included is included, the conduction electrons of the metal atom are more preferable because the electric conductivity is improved.

  A seventh aspect of the present invention is the electric contact mechanism for a small motor according to any one of the first to sixth aspects, wherein a metal is interposed in the carbon-based material.

  The present invention has either or both of metal interposition on the carbon-based material surface and metal inclusion in the carbon-based material, and by interposing the metal on the carbon-based material surface, A contact material that combines high electrical conductivity with the heat resistance, heat dissipation, and arc resistance of carbon-based materials can be realized. Furthermore, when a metal is included in the carbon-based material, the conduction electrons of the metal atom produce an effect of further improving the electrical conductivity of the carbon-based material. When electric conductivity is important, it is preferable to use a metal based on Au, Ag, Cu, Al, or an alloy containing them, and Ti is important when thermal properties and arc resistance are important. Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Pd, Pt, Fe, Co, refractory metals based on refractory elements such as Ni, or alloys containing them Preferably there is.

  The invention according to claim 8 is the electric contact mechanism for a small motor according to any one of 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 electric contact mechanism for a small motor.

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

  From the above, by applying the electric contact mechanism for a small motor of the present invention, the unexpected bending that occurs near the free end of the carbon-based material can be bundled with the carbon-based material, and an orientation effect can be reliably obtained, and flexible Since the brush has the ability to reliably follow the curved surface of the commutator and the brush and commutator are in stable contact with each other over a wide area, the generation of arc is suppressed, electrical wear is reduced, and mechanical sliding wear is reduced. An electric contact mechanism for a small motor having a contact material excellent in suppression, heat resistance and corrosion resistance, electric wear (electric corrosion), and excellent electrical conductivity can be formed.

  The present invention uses a fibrous carbon-based material as a material for a brush structure of an electric contact of a small motor, particularly a small motor with relatively large driving voltage or power consumption, and the length of the fibrous carbon-based material is several. Since it is formed of 100 μm to several mm, and the form thereof is a brush structure that is a brush-like form, mechanical sliding wear can be reduced, and furthermore, generation of arc can be suppressed. It is possible to reduce.

(First embodiment)
The schematic diagram of the contact material 1 of the contact mechanism of the small motor as 1st Embodiment is shown in FIG. The contact material 1 is made of a carbon-based material in a fiber shape, has a length L of several hundred μm to several mm, and is oriented substantially perpendicular to the contact material fixing surface.

  Next, the manufacturing method of the fibrous carbonaceous material of this 1st Embodiment is demonstrated. First, various carbon-based materials intertwined in a cotton-like shape were poured into a glass container containing an organic solvent such as an appropriately selected polymer and solvent to obtain a mixed liquid in which the carbon-based material was dispersed in the organic solvent. When the carbon-based material was dispersed in the liquid, it was sufficiently stirred or kneaded so that the carbon-based material was not unevenly distributed.

  Then, the obtained mixed liquid was 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 was pressurized and injected to obtain a fibrous carbon-based material oriented in the injection direction. . The fibrous carbon-based material was oriented in a substantially vertical direction on a 2 mm (D) × 0.1 mm (W) surface and adjusted to a length of 0.3 mm to obtain the contact material 1. The remaining organic solvent was removed using a solvent.

(Second Embodiment)
FIG. 2 shows a contact material 3 of a contact mechanism of a small motor as a second embodiment. The contact material 3 is formed of a thin sheet sheet in which carbon materials are entangled with each other. The thin-leaf sheet-like carbon-based material is laminated, and the contact material 3 is formed by orienting substantially perpendicular to the contact material fixing surface.

  Next, the manufacturing method of the fibrous carbonaceous material of this 2nd Embodiment is demonstrated. First, various carbon-based materials intertwined in a cotton-like shape were poured into a glass container containing an organic solvent such as an appropriately selected polymer and solvent to obtain a mixed liquid in which the carbon-based material was dispersed in the organic solvent. When the carbon-based material was dispersed in the liquid, it was sufficiently stirred or kneaded so that the carbon-based material was not unevenly distributed.

  The obtained mixed liquid was poured onto a filter having a pore diameter of 1 μm, filtered, and the deposit on the filter was peeled off to form a thin-leaf sheet-like carbon material. Furthermore, the sheet | seat orientated to the tension direction was able to be obtained by applying the tensile stress to the formed thin sheet-like carbon-type material to a uniaxial direction. These were oriented in a substantially vertical direction with respect to the contact material fixing surface and laminated to form the rectangular parallelepiped contact material 3 of 2 mm (D) × 0.1 mm (W) × 0.3 mm (H). The remaining organic solvent was removed using a solvent.

  A metal carbon compound was formed and fixed between the contact materials 1 and 3 obtained by the above production method and the elastic materials 2 and 4 having conductivity to form a brush shape. Energization between the contact material and the elastic material was confirmed using a tester.

  For example, when a conventional precious metal brush or carbon brush is mounted on a small motor, and a life test is performed with a drive voltage of 12 V and a drive mode of no-load forward rotation continuous operation, Burnout occurs and stops in 80 to 100 hours.

  In addition, a small motor mounted with a carbon brush causes contact failure due to wear of the brush and stops in about 90 hours. Conventional carbon brushes are prone to wear during sliding and have a large volume to compensate for the effects of wear and ensure the service life, but with the miniaturization, the volume that can be secured decreases, As a result, the life of the small motor has been greatly reduced.

  On the other hand, the use of the fibrous carbon-based material of the present invention as a contact material can be expected to improve the life several times to several tens of times compared to the conventional electric contact mechanism. This is because a carbon-based material is used for the contact material, it can withstand high power consumption, and its structure has flexibility, so there is little mechanical wear, and the contact material surely follows the commutator, This is because the electrical wear can be reduced by suppressing the generation of the arc.

  As described above, the electric contact mechanism for a small motor according to the present invention is suitable for a small motor, particularly a small motor with a large driving voltage or power consumption, and it is extremely effective to suppress the generation of arc itself when the motor is driven. It can be said that it is a simple structure.

  By using the electrical contact mechanism with the above structure, it is possible not only to suppress mechanical sliding wear and improve corrosion resistance, but also to suppress electrical wear, that is, the occurrence of arcs that directly cause electric corrosion. It becomes. In order to surely obtain the above effects, it is more practically preferable that the length is several hundred μm to several mm.

  The present invention uses not only mechanical sliding wear but also electrical sliding contact by using a fibrous carbon-based material that is entangled, oriented, and configured as a brush contact material in an electric contact mechanism for a small motor. Wear can be reduced and the durability of the electrical contact can be improved.

The schematic diagram which shows the 1st Embodiment of this invention Schematic diagram showing a second embodiment of the present invention Enlarged view of part a in FIG. Schematic diagram of cross section of conventional brush in Patent Document 1 The schematic diagram which shows schematic structure of the electrical contact apparatus in which the conventional contactor was integrated in patent document 2

Explanation of symbols

1, 3 Contact material 2, 4 Conductive elastic material

Claims (8)

In an electric contact mechanism for a small motor in which a brush in which a contact material is fixed to a conductive elastic material abuts and slides on a commutator and commutates to an armature connected to the commutator.
A carbon-based material is used for the contact material, and the carbon-based materials are entangled with each other to form a fiber shape, and the fibrous carbon-based material is oriented substantially perpendicular to the contact material fixing surface of the elastic material. An electrical contact mechanism for small motors.   2. The electric contact mechanism for a small motor according to claim 1, wherein the carbon material of the contact material is formed in a fiber shape so that the length is several hundreds μm to several mm. mechanism.   The electric 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 a derivative thereof. An electrical contact mechanism for a small motor, comprising a contact material formed into a fibrous shape by entanglement of at least one or more kinds of molecules.   3. The electric contact mechanism for a small motor according to claim 1, 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 network shape, and approximately one. An electric contact mechanism for a small motor, characterized in that it has a contact material that is oriented in a direction, is formed in a thin sheet shape, and is laminated so that the orientation direction is substantially constant.   3. The electric contact mechanism for a small motor according to claim 1, wherein at least one molecule of SWNT, MWNT, FNW, or a derivative thereof as a carbon-based material is entangled with each other and formed into a fiber shape. A compact motor comprising a contact material and a composite of contact materials entangled with each other in a mesh shape and formed in a thin sheet shape, and having a contact material oriented substantially perpendicular to the contact material fixing surface Electric contact mechanism.   6. The electric contact mechanism for a small motor according to claim 1, wherein SWNT, MWNT, FNW, or a derivative thereof includes a spherical fullerene or a metal-encapsulated spherical fullerene. .   7. The electric contact mechanism for a small motor according to claim 1, wherein a metal is interposed in the carbon-based material.   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 joined by using a metal. Contact mechanism.

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