JP2002343168A - Current-carrying slide body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a current carrying slide body superior in heat resistance/ electroconductivity/lubricity. SOLUTION: This is that which is coated with a greasy lubricant 25 composed of 20 to 30 wt.% graphite whose average particle size is from 5 to 30 μm and 70 to 80 wt.% perfluoropolyether 22 whose viscosity is from 200 to 350 so that the film thickness becomes 10 μm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding energizer for an electric device having a sliding energizing portion such as a movable contact or a movable member that is energized and slid during opening and closing.

[0002]

2. Description of the Related Art Sliding current-carrying parts, such as movable contacts and mover receivers of electric equipment, for example, circuit breakers, are subjected to frictional heat due to sliding and Joule heat due to current flow when a conductor base such as copper or aluminum is used. The contact resistance may increase due to oxidation due to the heat generated by the heat treatment. For this reason, in order to prevent oxidation and stably maintain the current carrying capacity of the sliding contact element and the sliding contact piece, the sliding contact surface of the important sliding energizing portion is coated with silver plating. . However, the coating treatment by silver plating may cause chipping of the coating due to sliding,
Once chipping occurs, abrasion proceeds rapidly and the base of the movable contact and the movable element receiver is easily exposed, so that an organic lubricant is generally used together.

(Conventional example 1) For example, Japanese Patent Laid-Open No. 9-30632
No. 6 discloses about 5% by weight of graphite and about 1% by weight.
A method in which a sliding current-carrying part of a movable contact of a circuit breaker is immersed in a liquid obtained by mixing perfluoropolyether with a fluorosolvent and then pulled up is described. Since the fluorine solvent in the sliding current-carrying portion is easily dried, as shown in FIG. 6, a state in which graphite 23 adheres to silver plating film 21 provided on copper substrate 7 using perfluoropolyether 22 as a binder. become.

(Conventional example 2) For example, JP-A-8-22858
Japanese Patent Application Laid-Open Publication No. H11-157, discloses that a sliding component is coated with a fluorine-based grease using perfluoropolyether as a base oil and PTFE (ethylene tetrafluoride) having a high chemical affinity with the base oil as a thickener. .

[0005]

In the invention described in the prior art 1, the perfluoropolyether 22 and the graphite 23 are adhered by immersion in a solution diluted with a solvent. About 2μm thick
However, it is difficult to use it for a current-carrying sliding part which is inferior in load resistance and has a high load, and has a short durability life. In addition, because of the dip coating method, appropriate coating could not be performed at a required coating location depending on the shape of the component. The invention described in Conventional Example 2 is one in which a fluorine-based grease using perfluoropolyether as a base oil and PTFE (ethylene tetrafluoride) as a thickener is applied to a current-carrying sliding portion. In this case, the perfluoropolyether thermally decomposes above 250 ° C.
Even if the temperature is lower than C, the diffusion and outflow may occur over time. When the perfluoropolyether is thermally degraded in this way, PT
Although the FE remains in the current-carrying portion, the thermally degraded PTFE has high insulation properties and low cleavage. Therefore, the self-lubricating property is not excellent, and there is a problem that a current-carrying contact failure occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a sliding electric conductor excellent in load resistance and lubricity at high temperatures.

[0007]

According to the present invention, there is provided a sliding current-carrying member provided with a sliding portion of a conductor having a silver-plated surface.
It contains 0 to 30% by weight of graphite and 70 to 80% by weight of perfluoropolyether, and has a consistency of 200 to 35%.
0 grease-like lubricant is applied.

The average particle size of graphite is 5-30.
By setting the particle size to μm, diffusion and outflow of perfluoropolyether from the grease-like lubricant is small, and a decrease in lubricity can be prevented.

Further, by setting the thickness of the applied grease-like lubricant to 10 μm or more, a sliding electric conductor having more excellent load resistance can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a cross-sectional view showing a surface state of a current-carrying sliding portion according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 7 denotes a copper base material having a thickness of 2 mm, for example, a sliding contact or a sliding contact piece in a switch or a circuit breaker. 21 is a silver plating film having a thickness of about 5 μm, 30 is a grease-like lubricant composed of perfluoropolyether 22 and graphite 23, and has a thickness of about 20 μm. Perfluoropolyether 22 is a fluorine-based synthetic lubricating oil that has high heat resistance and does not oxidize or decompose at 250 ° C. or lower, and does not produce a solid residue even when decomposed at a high temperature. And does not adversely affect wear resistance. Graphite 23 is a solid lubricant,
It has heat resistance of 400 ° C. or higher, high conductivity of specific resistance 10 ⁻² Ω · mm, and high cleavage (high cleavage) due to a layered crystal structure. Here, the grease-like lubricant means a substance similar to the properties of grease which is a semi-solid lubricant composed of a base oil and a thickener, and the perfluoropolyether 22 and the graphite 23 are each a base in the grease. Equivalent to oil and thickener.

The proportion of graphite 23 in the grease-like lubricant is preferably in the range of 20 to 30% by weight. When the ratio of the graphite 23 is less than 20% by weight, the degree of oil separation increases, and the perfluoropolyether 22 easily flows out of the grease-like lubricant. On the other hand, if it is more than 30% by weight, the amount of graphite 23 is large, so that it is difficult to disperse in the perfluoropolyether 22, and the production of a grease-like lubricant tends to be difficult.

The consistency of the grease-like lubricant is 20
A range of 0 to 350 is desirable. When the consistency is higher than 350, it is unsuitably soft for use as a grease-like lubricant and has a high degree of oil separation. As a result, it was difficult to maintain the shape of the grease-like lubricant, the lubricant retention on the sliding surface was poor, and the lubrication performance tended to decrease. on the other hand,
When the consistency is lower than 200, it is unsuitably hard to use as a grease-like lubricant, the sliding resistance on the sliding surface increases, and the required lubricity tends to be not obtained. .

The average particle size of the graphite 23 is 5 to 5.
A range of 30 μm is desirable. That is, when the average particle size of the graphite 23 is less than 5 μm, the crystallinity is poor, cleavage is difficult, the friction coefficient of the sliding portion is increased, and the sliding surface is easily worn. On the other hand, when the average particle size of the graphite 23 is larger than 30 μm, the degree of oil separation of the grease-like lubricant increases. When the degree of oil separation increases, the perfluoropolyether 22 diffuses out of the grease-like lubricant, and the lubricity decreases. In addition, when the perfluoropolyether 22 flowing out of the sliding surface is applied to a peripheral portion of the sliding surface, for example, to a circuit breaker, there is a possibility that the perfluoropolyether 22 adheres to a mechanism of the circuit breaker and exerts an adverse effect.

In the grease-like lubricant for the current-sliding body according to the present invention, the graphite 23 is preferably a scaly natural graphite having a high cleavage property and a high effect of reducing friction and wear.

As described above, perfluoropolyether 2
By applying a grease-like lubricant obtained by kneading No. 2 with graphite 23 as a solid lubricant, for example, by applying a brush, it was possible to obtain a sliding energizer having excellent sliding energizing performance. That is, in the application (immersion) method according to Conventional Example 1, the lubricant adhering to the sliding portion is a thin film, but in the method of the present invention, the lubricant is grease-like, so that a thick film can be applied to the sliding portion. Lubrication performance and load resistance are improved. In addition, since the conventional example 1 was an immersion method, it was not possible to perform appropriate application at a required application location. However, in the method of the present invention,
Since the lubricant is in the form of grease, it has become possible to locally apply the lubricant, which was difficult with the immersion method.

Further, in the above-mentioned conventional example, the case where a lubricant is applied is described. However, since the lubricant is usually applied by diluting with a solvent, the film thickness of the perfluoropolyether 22 is large. It is about 2μm and graphite 23
Is small. On the other hand, the thing of the present invention has a strong adhesive force because it is grease-like, and it is hard to flow,
The film thickness can be 10 μm or more. 10μ thickness
When the thickness can be increased to m or more, the graphite 23 and the perfluoropolyether 22 are adhered in a large amount, so that the load resistance is excellent and the heat resistance is also excellent. Further, even if the perfluoropolyether 22 and the graphite 23 are temporarily removed from the current-carrying part by the sliding operation, the perfluoropolyether 22 and the graphite 23 which are filled around are instantaneously supplemented. As compared with the example, the sliding current conductor is excellent in stability and lubricity.

Further, the conventional PTFE (ethylene tetrafluoride) has a high insulating property and does not have a cleavage property, so that when perfluoropolyether flows out, there is a possibility that a current-carrying contact failure may occur. According to the present invention, graphite 23 has a heat resistance of 400 ° C. or more and a specific resistance of 10 −2 Ω.
-High conductivity of 1 mm and high cleavage due to the layered crystal structure, so that even if the perfluoropolyether 22 flows out, no current contact failure occurs, and the current-carrying durability of the sliding current-carrying portion can be maintained.

Embodiment 1 FIG. Regarding the characteristics of the grease-like lubricant in the above embodiment, materials, measurement methods, measurement results, and the like will be described in actual examples. (Material) Sumitec F oil manufactured by Sumiko Lubricant Co., Ltd. was used as perfluoropolyether 22 in graphite 2
As scale 3, graphite of flaky natural graphite was used. (Grease-like lubricant preparation and measurement items) Perfluoropolyether 22 and graphite 23 were mixed at 25 ° C ± 0.5 °.
The consistency, the dropping point, the degree of oil separation, and the lubricating properties of the grease-like lubricant obtained by mixing 60 times with C were measured. The measurement results for each graphite ratio and each graphite particle size are shown in Tables 1 and 2 below, respectively.

(Measurement method) The consistency is one of the indexes indicating the hardness of grease, and is defined by Japanese Industrial Standard JIS K222.
The measurement was carried out according to the rules given in 5.3 of O. The dropping point is one of the indices indicating the phase change of the grease depending on the temperature, and was measured according to the provisions in 5.4 of JIS K222O. The degree of oil separation is one of the indexes indicating the flow of the base oil from the grease, and is based on the conditions described in 5.7 of JIS K222O under the condition (% by weight) of the base oil which flowed out at 100 ° C for 24 hours. Measured.

(Measurement results) When the graphite ratio in the grease-like lubricant was in the range of 20 to 30% by weight, the characteristics of dropping point and oil release were excellent. When the ratio of graphite indicated by “*” in Table 1 was 10% by weight, the test was not performed because it was not grease-like. When the ratio of graphite indicated by “**” in Table 1 was 40% by weight, the ratio of graphite was high, and the graphite was not uniformly dispersed.

The consistency of the grease-like lubricant is 20
It has been found that a range of 0 to 350 is desirable. When the consistency was higher than 350, it was unsuitably soft for use as a grease-like lubricant and the oil separation increased. As a result, it was difficult to maintain the shape of the grease-like lubricant, the lubricant retention on the sliding surface was deteriorated, and the lubrication performance tended to decrease. On the other hand, if the consistency is lower than 200,
When used as a grease-like lubricant, it is unsuitably hard, and the sliding resistance of the sliding portion tends to increase, resulting in poor lubricity.

The average particle size of graphite is 5 to 30.
It was found that, in the range of μm, preferably 20 to 25 μm, the properties of dropping point and oil release were excellent, and the lubrication properties were comprehensively excellent. If the average particle size of graphite is less than 5 μm, the crystallinity becomes poor, cleavage becomes difficult, the friction coefficient of the sliding portion increases, and the sliding surface is easily worn. On the other hand, when the average particle size of graphite is larger than 30 μm, the degree of oil release of the grease-like lubricant increases.

[0023]

[Table 1]

[0024]

[Table 2]

Embodiment 2 In the second embodiment, a case will be described in which the grease-like lubricant of the first embodiment is applied to a sliding contact portion serving as a rotation center of a movable contact of a circuit breaker. FIG. 2 is a side sectional view of a circuit breaker according to Embodiment 2 of the present invention, FIG. 3 is a plan view partially showing a movable contact device of the circuit breaker of FIG. 2, and FIG. It is a side view which shows the movable contactor apparatus of a circuit breaker in partial cross section. In the figure, reference numerals 1 and 2 denote a synthetic resin base and a cover forming a main body case of the circuit breaker. Reference numeral 3 denotes a fixed conductor on the power supply side fixed to the base 1, and a fixed contact 4 is fixed to a tip portion. Reference numeral 5 denotes an automatic tripping device, and reference numeral 6 denotes a load-side fixed conductor connected to the automatic tripping device 5. Reference numeral 7 denotes a silver-plated copper movable contact having a movable contact 8 which comes into contact with and separates from the fixed contact 4.

Reference numeral 9 denotes a movable plate receiver made of a silver-plated copper plate, and a pair of support plates 9a and 9 each formed in an L shape.
b (see FIGS. 3 and 4). Support plate 9
One end of each of a and 9b is connected to a connection conductor 19 connected to the automatic tripping device 5. The support plate 9
a and 9b are mounting screws 20 screwed into the screw holes 9c and 9d.
Is fixed to the base 1 together with the connection conductor 19.
Reference numeral 10 denotes a movable contact 7 sandwiched between a pair of support plates 9a and 9b.
The movable contact 7 is rotatably supported by the movable member receiver 9 via an opening / closing shaft 10 with an opening / closing shaft inserted through holes opened in the support plates 9a and 9b. Reference numeral 11 denotes a synthetic resin holder, which is rotatably supported by the base 1 and is opened and closed (rotated) by an opening and closing mechanism described later. Reference numeral 11a denotes a concave portion formed in the holder 11, which holds both ends of the opening / closing shaft 10. Reference numerals 12 denote coil-shaped compression springs (see FIGS. 3 and 4) fitted to both sides of the opening / closing shaft 10, respectively, and support plates 9a and 9 of the holder 11 and the movable member receiver 9.
b, and presses the inner wall surfaces of the support plates 9 a and 9 b against the side surface of the movable contact 7.

A contact pressure spring 13 is stretched between the holder 11 and the movable contact 7. 14 is an operation handle, 1
Reference numeral 5 denotes a circuit breaker opening / closing mechanism, which includes a handle receiver 15a, a cradle 15b, an upper link 15c, a lower link 15d, and the like. 16 is a stopper pin provided on the cradle 15b, 17 is a connection pin for connecting the lower link 15d to the holder 11, and 18 is an arc extinguishing chamber. In the closed state of the movable contact device, in FIG. 2, the fixed conductor 3 on the power supply side → the fixed contact 4 → the movable contact 8 → the movable contact 7 → the movable receiver 9 → the connecting conductor 19 → the automatic tripping device 5
→ An electric current flows like the fixed conductor 6 on the load side. In this case, in a circuit breaker corresponding to a large current circuit, the spring constant of the compression spring 12 is increased in order to resist the electromagnetic repulsion of the energizing contact portion, and the sliding surface of the movable contact 7 and the movable member receiver 9 is increased. The contact pressure needs to be increased.

In the lubricant of the first conventional example, the movable contact device (see FIGS. 3 and 4) equivalent to the second embodiment uses a lubricant 140 that is higher than the maximum temperature of the energized portion assumed at the time of the rated maximum load of the circuit breaker. After holding at ゜ C for one month, a reciprocating sliding test was performed, and the re-sliding test was passed 30,000 times. However, in the specification in which the spring constant of the compression spring 12 was increased for a large current circuit, a sliding test of 30,000 times was impossible. on the other hand,
Under these conditions, the case where the grease-like lubricant of the first embodiment was applied showed that the change in contact resistance was within the allowable range even after the 30,000-time sliding test, and was acceptable. Further, no clear wear was detected in the measurement of the wear amount due to the change in the plating film thickness using a fluorescent X-ray film thickness meter.

In Conventional Example 1, perfluoropolyether 22
When the contact pressure is large, the oil film easily breaks and the lubricating performance tends to decrease because the film thickness is as thin as about 2 μm. It is considered to have stable lubricating performance because it adheres to the surface. Next, as an overload test for the circuit breaker, after generating abnormal heat due to the passage of an excessive current for a short time,
As a result of performing the reciprocating sliding test again, no abnormality was found in both lubricity and conductive properties. As described above, it is possible to obtain a movable contact device of a circuit breaker which has excellent load resistance and heat resistance and has little change in sliding resistance with time.

Embodiment 3 In a third embodiment, a case will be described in which the grease-like lubricant of the first embodiment is applied to a sliding connection terminal of a switching device. FIG. 5 is a configuration diagram showing a sliding connection terminal of the switchgear according to the third embodiment. Of the circuit breakers and disconnecting switchgear, particularly those housed in cubicles, the input and output main circuit terminals have a sliding connection structure that can be inserted and removed for maintenance, replacement of the switchgear, etc. .

In FIG. 5, reference numeral 27 denotes a copper fixed terminal which remains on the cubicle body side when the switchgear is pulled out, and is plated with silver. Reference numeral 25 denotes a circuit terminal conductor on the switchgear side, and reference numeral 24 denotes a copper contact plate fixed to the terminal conductor 25 with screws 26, and is provided with silver plating. Reference numeral 28 denotes a contact spring. The minimum distance between the open ends of the contact plate 24 is smaller than the thickness of the fixed terminal 27 in the state shown in FIG. In this configuration, the contact plate is pressed from the outside by the contact spring 28 to apply the connection pressure to the fixed terminal 27 so as to be connected. In the third embodiment, the grease-like lubricant of the first embodiment is applied to the sliding surface between the fixed terminal 27 and the contact terminal 25.

Although the sliding portion of the second embodiment is a surface contact,
Since the sliding connection terminal of the third embodiment is in line contact, the contact pressure is high. In addition, since the sliding surfaces are always in contact with each other, the circuit terminal conductors 2
In No. 5, the grease-like lubricant is easily peeled off. However, by using the grease-like lubricant according to the present invention, the sliding connection terminal of the third embodiment can exhibit stable lubrication characteristics for a long time.

In each of the above embodiments, examples have been described in which the grease-like lubricant according to the present invention is applied to the movable contact of the circuit breaker and the sliding connection terminal of the switching device. Instead, the grease-like lubricant according to the present invention can be applied to the current-carrying parts of all electric devices that require heat resistance, conductivity, and lubricity.

[0034]

According to the present invention, the current-carrying member has a sliding portion of 20 to 30% by weight of a conductor whose surface is coated with silver.
And 70 to 80% by weight of perfluoropolyether, and a grease-like lubricant having a consistency of 200 to 350 is applied, so that the grease-like lubricant can be formed into a thick film, and the load resistance, A sliding energizer having excellent lubrication at high temperatures can be obtained.

The average particle size of graphite is 5 to 30.
By setting the thickness to μm, a sliding conductor having more excellent lubricity can be obtained.

Further, the thickness of the grease-like lubricant is 10 μm.
By setting m or more, a sliding current-carrying body having more excellent load resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a surface state of a current-carrying sliding portion according to Embodiment 1 of the present invention.

FIG. 2 is a side sectional view of a circuit breaker according to Embodiment 2 of the present invention.

FIG. 3 is an enlarged plan view showing a movable contact device of the circuit breaker of FIG. 2 in a partial cross section.

FIG. 4 is an enlarged side view showing the movable contact device of the circuit breaker of FIG. 2 in a partial cross section.

FIG. 5 is a configuration diagram showing a sliding connection terminal of the switchgear according to Embodiment 3 of the present invention.

FIG. 6 is a cross-sectional view showing a surface state of a conventional sliding energizing section.

[Explanation of symbols]

Reference Signs List 1 base, 2 cover, 3 fixed conductor, 4 fixed contact, 5 automatic trip device, 6 fixed conductor, 7 movable contact, 9 mover receiver, 9a, 9b support plate, 10 opening / closing axis, 11 holder, 12 compression spring , 13 contact pressure spring, 14 operating handle, 15 opening / closing mechanism, 16 stopper pin, 17 connecting pin, 18 arc extinguishing chamber, 19 connection conductor, 21 silver plating film, 22 perfluoropolyether, 23 graphite, 24 contact plate, 25 Circuit terminal conductor on switchgear side, 27 fixed terminal, 28 contact plate, 30 grease-like lubricant.

Claims (3)

[Claims] 1. A sliding part of a conductor whose surface has been subjected to silver plating contains 20 to 30% by weight of graphite and 70 to 80% by weight of perfluoropolyether and has a consistency of 20%.
A sliding energizer coated with a grease-like lubricant of 0 to 350. 2. An average particle size of graphite is 5 to 30 μm.
2. The sliding energizer according to claim 1, wherein: 3. The applied grease-like lubricant has a thickness of 1
The sliding energizer according to claim 1 or 2, wherein the thickness is 0 µm or more.