JP4991983B2 - Sliding contact structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention typically has both a mechanical inter-sliding function between two members that are in relative motion and an electrical interconnection function, as seen in the example of a brush and slip ring in an electric motor. In particular, the sliding contact surface that governs the quality of the electrical interconnection function exclusively of both functions of such a sliding contact structure. This is related to the gradual improvement of electrical resistance.
[0002]
[Prior art]
With respect to the conventional structure of this type, the composition of a conductive agent including metal particles such as copper / nickel alloy (Cu—Ni), tin (Sn), titanium (Ti), boron nitride (BN), graphite, 2 A cylindrical sliding contact body formed of a sintered body in which the composition of a solid lubricant containing material particles such as tungsten sulfide (WS ₂ ) and mica (Si, Al, K) is uniformly distributed throughout. However, for example, it is widely used as a sliding contact member for a brush of an electric motor, and a sliding contact surface is formed on one end surface of such a cylindrical sintered body. For example, conductive sliding contacts such as copper rings, which are frequently used for slip rings of electric motors, and metal flat plates, which are frequently used for sliding members of other industrial machines, are relatively slidable. Sliding configured to slidably contact Tactile structure is known.
[0003]
[Problems to be solved by the invention]
However, in such a conventional sliding contact structure, the contact resistance that governs the electrical interconnection function, that is, the electrical resistance at the sliding contact surface, compared to the contact resistance between metals, For example, a value of about 18 mΩ is generally exhibited with respect to a 8.5 mmφ circular sliding contact surface under the adoption of a sliding contact body made of copper, for example. On the sliding contact surface formed on the sintered body as the sliding contact body of this type of sliding contact structure, the composition of the conductive agent and the composition of the solid lubricant are particles or granules on the order of 100 microns. Exposed in the form of a uniform distribution of lumps, which provides an electrical interconnection function in the form of a decreasing electrical resistance at the sliding contact surface, which is caused by the particles or granular lumps of conductive agent. The enhancement is realized at the expense of an increased mechanical inter-sliding contact function in the form of a decreasing coefficient of friction at the sliding contact surface as provided by the solid lubricant particles or granular masses. Therefore, harmony of the contradictory requirements of decreasing electric resistance and decreasing friction coefficient is achieved. Therefore, it can be said that it inherently tends to exhibit high resistance relative to the electrical resistance at the sliding contact surface between the metals.
[0004]
Furthermore, regarding the electrical resistance at the sliding contact surface, the mutual resistance caused by the interdependent action of the currents that flow in a concentrated manner in the particles or granular masses of the conductive agent composition uniformly distributed on the sliding contact surface. The generation mechanism of resistance is described in Greenwood theory (Source: JA Greenwood, “Consistency resistance and the real area of contact”, Brit. J. Appl. Phys., Vol. 17, 16-32), p. 1966), the inventor of the present application has conducted empirical research on the application of this theory to the generation mechanism of electrical resistance at the sliding contact surface of the sintered body. Conductive agent particles uniformly distributed in the central region on the sliding contact surface The lumps generate a relatively large mutual resistance due to the overall interaction from the current concentrated in a point on the conductive agent particles etc. on the entire sliding contact surface. While the electrical resistance on the upper surface is substantially controlled, the conductive agent particles distributed uniformly in the peripheral region on the sliding contact surface are exclusively used for the adjacent conductive agent particles in the peripheral region. Since the interaction from the current concentrated in a point only generates a relatively small mutual resistance, the current on the sliding contact surface is concentrated on the conductive agent particles in the peripheral region. (Source: Y. Watanabe, Analysis of Contact Resistance in Composite Materials for Sliding Contacts, IEICE Trans, E ectron.Japan vol.E83-C No.9.pp.1409-1413September 2000). According to the empirical clarification of the present inventor, the mutual resistance of the green wood generated on the sliding contact surface of the sintered body is due to the mixing of particles or agglomerates of solid lubricant for decreasing the friction coefficient there. Since the electrical resistance of the excess element exceeds the electrical resistance of the compensation, the electrical resistance generated on the entire sliding contact surface is large for the momentum and the decrease in the friction coefficient. There is a problem that the application range of the sliding contact structure is limited.
[0005]
Therefore, by suppressing the electrical resistance caused by the mutual resistance of the excess element to a minimum, the sintered body can be obtained without sacrificing the decreasing effect of the friction coefficient due to mixing of particles or granular lump of solid lubricant. It is an object of the invention according to claims 1 to 3 to provide a sliding contact structure which can greatly reduce the overall electrical resistance on the sliding contact surface.
[0006]
[Means for Solving the Problems]
In view of the problem of limited application range due to large electrical resistance on the sliding contact surface in the conventional structure, the invention according to claims 1 to 3 is a peripheral device on the sliding contact surface with little mutual resistance. In the region, the composition of the conductive agent is distributed at a high density, and from the opposite viewpoint, the composition of the solid lubricant is distributed at a high density in the central region on the sliding contact surface where the occurrence of mutual resistance is remarkable. By solving the above problems, the overall electrical resistance can be greatly reduced without sacrificing the decreasing effect of the friction coefficient on the sliding contact surface of the sintered body. A sliding contact structure is provided.
[0007]
[Action]
In the first aspect of the present invention, the sliding contact body is formed of a sintered body composed of a conductive agent composition and a solid lubricant composition, and has a sliding contact surface on one surface of the cube. The conductive sliding contact body includes a sliding contact surface that is slidably contacted relative to the sliding contact surface of the sliding contact body. The sliding contact surface of the sliding contact body The density of the conductive agent composition in the upper peripheral region is distributed so as to be relatively higher than the density of the conductive agent in the central region on the sliding contact surface. Current concentrates on particles or granular lumps of a relatively high density conductive agent composition, so that the current passes on the sliding contact surface against the relatively reduced mutual resistance, The relatively dense solid lubricant composition particles or granular masses in the region will exclusively reduce the coefficient of friction on the sliding contact surface. Acting on.
[0008]
According to a second aspect of the present invention, particles or granular masses of copper / nickel alloy (Cu—Ni), tin (Sn), and titanium (Ti) as the composition of the conductive agent on the sliding contact surface are in sliding contact. Boron nitride (BN), graphite, and tungsten disulfide as a composition of the solid lubricant of the sliding contact body, in which current is concentrated in a relatively high density in the peripheral region on the surface. (WS ₂ ), mica (Si, Al, K) particles or granular lumps are relatively densely distributed in the central region on the sliding contact surface, and the friction coefficient there is gradually decreased. Works.
According to a third aspect of the present invention, the sliding contact body is a cylindrical body formed of a sintered body, and one end surface thereof acts as a sliding contact surface.
[0009]
Embodiment
An embodiment for supporting the invention according to claims 1 to 3 will be described below with reference to FIGS. As shown in the perspective view of the main part extraction in FIG. 1, the sliding contact structure P is composed of the sliding contact body A and the sliding contact body B, and is fixed to the sliding contact body A. A current supplied from a connected power supply system (not shown) is fixedly connected via the sliding contact body A to a sliding contact body B arranged so as to be slidable relative to the current. It flows into a load system (not shown). The sliding contact body A is a cylindrical firing formed by subjecting a mixture, which will be described later, to an after-mentioned sintering process in the outer region c1 of the peripheral region and the core region c2 of the central region surrounded by the outer region. It is comprised by the coupling body c3. The aforementioned sliding contact body A, the sliding contact surface c4 is provided which is formed on one end surface of the circular column as a sliding contact member. On the other hand, the sliding contact member slides RECEIVING member disposed against the A B is driven by an unillustrated rotary drive mechanism connecting the central opening b1, conductive disk which rotates in the counterclockwise direction in the drawing, Typically, it is comprised with the disk b2 made from copper (Cu), and the sliding contact surface b3 formed in the plane is provided on the surface of the disk b2. The sliding contact surface b3 is in sliding contact with the sliding contact surface c4 on the sliding contact body A side so as to be relatively slidable between the sliding contact body A and the sliding contact body B. mechanical mutual sliding function, both electrical interconnections function between the two is simultaneously ensured. In such a configuration, the outer cover c1 in the peripheral region of the cylindrical sintered body c3 of the sliding contact body A and the core portion c2 in the central region of the sintered body have different conductive agent compositions or solid lubricants at different densities. The particles or granular lumps of the agent composition are distributed. The particles or granular lumps such as copper (Cu) contained in the conductive agent composition ensure the action of reducing electric resistance, and the solid lubricant composition of 100 microns. -Tungsten disulfide (WS2), graphite, etc. rubbed out from the ordered particles or granular lump also move to the sliding contact surface b3 side that slides oppositely, and the sliding contact surface and the sliding contact surface c4 By forming a lubricating film between the two, a reduction in mechanical friction (coefficient of friction) between both surfaces is ensured. As a result, between the sliding contact surface c4 of the sliding contact body A and the sliding contact surface b3 of the sliding contact body B, energization with low electrical resistance is ensured under the pressure contact sliding state with mechanical friction. It is what is done.
[0010]
As clearly shown in the partial cross section of FIG. 2, the outer cover portion c1 in the peripheral region of the cylindrical sintered body c3 of the sliding contact body A and the core portion c2 in the central region of the sintered body c3 are provided. Is made of boron nitride (BN), graphite, tungsten dioxide (WS2), mica (Si, Al, K), etc. as the composition of the solid lubricant, and copper (Cu) particles or granular lumps as the composition of the conductive agent. The mixtures c1 and c2 are mixed at different densities for both parts c1 and c2.
[0011]
That is, in the specific configuration of the embodiment shown in FIG. 2, the columnar sintered body c3 extends along the columnar center line and serves as a peripheral region on the sliding contact surface c4 on one end surface. A mantle portion c1 which is exposed to face the sliding contact surface b3, and extends along the central axis surrounded by the mantle portion, and serves as a central region on the sliding contact surface c4. The core portion c2 facing and exposed to the surface b3 is integrally sintered so that a cylindrical body is formed. In the outer shell portion c1, particles or granular lumps of the conductive agent composition are fixed lubricant composition. In contrast, in the core portion c2, particles or granular lumps of the solid lubricant composition are densely distributed relative to that of the conductive agent composition. As a result, the density of particles or granular lumps of the conductive agent composition on the sliding contact surface c4 of the sliding contact body A is in the peripheral region corresponding to the mantle portion c1 of the sliding contact surface c4. The sintered body c3 is manufactured so as to be higher relative to that of the central region of the surface c4 corresponding to the core portion c2.
[0012]
The transition of the distribution density of the particles or granular masses of the conductive agent composition in the buffer region in the vicinity of the boundary perpendicular to the radial direction between the core portion c2 and the mantle portion c1 is as in the configuration of the embodiment shown in FIG. These may be discrete (stepped), but may be continuous as shown. In addition, the conductive agent composition in the mantle portion c1 of the sintered body c3 shown in FIG. 2 is not limited to copper (Cu), but generally copper-nickel alloy (90Cu-10Ni), tin A matrix material containing a conductive agent composition such as (Sn) or titanium (Ti) is also preferably used.
[0013]
【Example】
The perspective view of FIG. 3 shows a sintered body d3 as a conventional sliding contact body A, and a cylinder containing particles or granular masses of a conductive agent composition and a solid lubricant composition in a uniform distribution. The sliding contact surface d4 is provided in the one end surface. Such a conventional composite material sintered body d3 manufactured under the following specifications (CMML-1) is a reference for performance evaluation of the sintered body c3 of the embodiment of the present invention. Prepared as a specimen.
[Shape dimensions]
Diameter: 8.5 mmφ cylindrical body [composition of the entire conductive material of sintered body d3 (Wt%)]
Copper-nickel alloy (90Cu-10Ni): 80.748
Tin (Sn): 7.099
Titanium (Ti): 0.887
[Composition of the entire solid lubricant (Wt%) of sintered body d3]
Boron nitride (BN): 0.229
Graphite: 2.364
Tungsten disulfide (WS ₂ ): 7.609
Mica: 1.064
[0014]
A cylindrical body made of copper (Cu) having the same appearance as that of FIG. 3 and having a sliding contact surface on one end face thereof is often used as the sliding contact body A. Such a conventional sliding contact body A made of a metal material, which is manufactured under the following specifications (Cu), is a reference specimen for performance evaluation of the sintered body c3 of the embodiment of the present invention. Prepared as.
[Shape dimensions]
Diameter: 8.5 mmφ cylinder [total conductive agent composition (Wt%)]
Copper (Cu): 100
[Composition of the entire solid lubricant (Wt%)]
None.
[0015]
The following specifications (CMML-1W) were manufactured as a sintered body c3 of the sample of the example to be evaluated for performance in comparison with the above two reference samples.
[Shape dimensions]
Outer diameter: 8.5 mmφ, inner diameter 5.0 mmφ sleeve diameter 5.0 mmφ core portion [conducting agent composition of outer mantle portion c 1 (Wt%)]
Copper-nickel alloy (90Cu-10Ni): 78.669
Tin (Sn): 6.916
Titanium (Ti): 0.864
However, the composition of the solid lubricant is not contained.
[Lubricant composition of core portion c2 (Wt%)]
Boron nitride (BN): 0.276
Graphite: 2.843
Tungsten disulfide (WS ₂ ): 9.152
Mica: 1.280
However, the composition of the conductive gas agent is not contained.
[0016]
Here, the sintered body c3 of the sample (CMML-1W) of the example whose performance is to be evaluated is the reference sample (CMML-) of the composite material described above in the weight% distribution of the contained composition per unit axial length (unit volume). The identity with the sintered body d3 of 1) is maintained. Therefore, only the conductive agent composition of the conductive agent composition and the solid lubricant composition that are uniformly distributed in the sintered body d3 of the reference specimen (CMML-1) of the composite material is collected in the mantle portion c1. Thus, it can be said that the structure in which all of the remaining lubricant composition is concentrated in the core portion c2 is the sintered body c3 of the sample (CMML-1W) of the example.
[0017]
Here, referring again to FIG. 1, the composite material reference specimen (CMML-1) and the sliding contact surface b3 on the copper (Cu) disk b2 that is rotationally driven as the sliding contact B Each sliding contact surface of the reference specimen (Cu) of the metal material and the specimen (CMML-1W) of the embodiment of the present invention is subjected to a relative rotational speed of 10 RPM (relative peripheral speed of 0.0105 m / min) under a pressing force of 100 g. In order to empirically compare and evaluate the electrical performance of the specimen with respect to the reference specimen, the contact resistance (electrical resistance) between the sliding contact face and the sliding contact face is set to the value of the disk b2. FIG . 4 is an electrical characteristic diagram measured as a total average value for each cumulative number of rotations (up to 500) and plotted for each amount of current passing between the sliding contact surface and the sliding contact surface . The empirical contrast of the mechanical performance of the specimen relative to the reference specimen Therefore, the friction coefficient between the sliding contact surface and the sliding contact surface is measured as a total average value for each cumulative number of rotations (up to 500 times) of the disk b2, and the sliding contact surface and the sliding contact surface FIG . 5 is a mechanical characteristic diagram plotted for each amount of current passing between the two. According to the electrical characteristic diagram of FIG. 4 , the contact resistance of the sample (CMML-1W) of the example of the present invention shows a low value of about 3 to 4 mΩ in a passing current amount region of 10 A or less, and 5 A Compared to the reference sample (CMML-1) of the composite material that shows approximately 18 mΩ in the following passing current amount region, it is significantly lower than that of the composite material reference sample (CMML-1). ) Is roughly comparable.
[0018]
Furthermore, according to the mechanical characteristic diagram of FIG. 5 , the friction coefficient of the sample (CMML-1W) of the example of the present invention is a low value of about 0.2 to 0.3 in the passing current amount region of 10 A or less. In the same passing current amount region, it is much lower than the reference sample (Cu) of the metal material showing 1.2 to 1.8, and moreover, the composite material sample (CMML) in the same passing current amount region A gradual improvement is recognized for the value of -1). As described above, based on the electrical characteristic diagram of FIG . 4 and the mechanical characteristics of FIG . 5 , the sliding contact structure of the present invention reduces the friction coefficient by mixing the solid lubricant composition particles or granular lumps. The overall electrical resistance on the sliding contact surface of the sintered body can be greatly reduced without sacrificing at all, and the electrical interconnection function on the sliding contact surface can be enhanced. It was proved that it meets the contradictory demand of enhancing the mechanical sliding contact function.
[0019]
In addition, the sintered body c3 of the sliding contact body A exemplified as the above-described embodiment is formed in a cylindrical body , and is provided with a sliding contact surface c4 having a circular cross section at one end surface. Therefore, the sliding contact surface c4 is only required to have a mechanical mutual sliding function and an electrical interconnection function with the sliding contact surface b3 that is in sliding contact with each other. It never is, cuboid triangular or cross a square-shaped cross-section triangular also be employed as appropriate, if Fuen encompasses all of these, in the sense of having a closed contour in three-dimensional space Three-dimensional is enough.
[Brief description of the drawings]
1 to 2 and FIGS. 4 to 5 relate to an embodiment of the present invention.
FIG. 1 is a perspective view showing a main part of a sliding structure P in an extracted manner.
FIG. 2 is a partial cross-sectional perspective view showing an example of the structure of a sliding contact body A. FIG.
FIG. 3 is a perspective view showing an example of a structure of a conventional sliding contact body A. FIG.
FIG. 4 is an electrical characteristic diagram showing electrical resistance between the sliding contact surfaces c4 and d4 and the sliding contact surface b3 .
FIG. 5 is a mechanical characteristic diagram showing a coefficient of friction between the sliding contact surfaces c4 and d4 and the sliding contact surface b3 .
[Explanation of symbols]
A Sliding contact body B Sliding contact body P Sliding contact structure c1 Circle-like mantle
c2 Cylindrical core part
Sintered body of c3 and d3 mixture
c4, d4 sliding contact surface b1 center opening b2 conductive disc b3 sliding contact surface

Claims (3)

A sliding contact body having a sliding contact surface on one surface of a solid body integrally formed as a sintered body composed of a conductive agent composition and a solid lubricant composition, and sliding contact of the sliding contact body A conductive sliding contact surface having a sliding contact surface that is in contact with the surface so as to be freely slidable relative to the surface. The conductive agent composition particles or granular lumps are distributed such that the density of the granular lumps is relatively higher than the density of the conductive agent composition particles or granular lumps in the central region of the sliding contact body, The density of the solid lubricant composition particles or granular lumps in the central region of the sliding contact body is relative to the density of the solid lubricant composition particles or granular lumps in the peripheral region of the sliding contact body. as increases, the sliding contact, characterized in that the particles or the granular mass of the solid lubricant are distributed Structure. The composition of the conductive agent of the sliding contact includes copper / nickel alloy (Cu—Ni), tin (Sn), and titanium (Ti), and the composition of the solid lubricant of the sliding contact is nitrided The sliding contact structure according to claim 1, comprising boron (BN), graphite, tungsten disulfide (WS ₂ ), and mica (Si, Al, K). The sliding contact structure according to claim 1, wherein the sliding contact body includes a sliding contact surface on one end surface of a cylindrical body formed of the sintered body.

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