JPH05219603A - Current collector - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the abrasion resistance of the contact plate used in the current collector of an electric vehicle and to improve the dynamic followability during running by reducing the weight. [Structure] Conductive ceramics whose sliding portion is composed of one or more kinds of compounds, or ceramics base composite material containing conductive ceramics as a main material and one or more kinds of auxiliary materials for improving toughness and lubricity ( It is a current collecting strip characterized by being composed of CMC).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact plate used in a vehicle current collector.

[0002]

2. Description of the Related Art Conventionally, a powder sintered body containing iron, copper, or carbon as a main component has been mainly used for a contact plate of a current collector for a vehicle. The current collector sliding plate collects current while sliding on the trolley wire while the vehicle is traveling, and therefore it is required to have abrasion resistance and heat resistance against arc heat generated by disconnection. All of the metal-based friction plates having iron or copper as a main component have the advantages of high conductivity and high mechanical strength, and have an overwhelming track record of use including high-speed vehicles. However, since the trolley wire of the copper component is metal-to-metal contact, the lubricant is mixed to improve the wear resistance, but as the speed of the vehicle increases, the wear rate increases, which is a maintenance problem. ing. The reason for this is that the higher the speed of the train, the more likely it is that the trolley wire will separate from the trolley wire, and the heat generated by the arc will melt part of the strip. One of the causes of derailment is that these metal-based contact plates have a large mass and occupy most of the sprung mass of the pantograph, which deteriorates the dynamic followability of the vehicle motion and the trolley wire motion. There is also a point. On the other hand, carbon-based friction plates are relatively lightweight, and since carbon itself has lubricity, it has a characteristic that metal-based friction plates are less aggressive to trolley wires, but it has low electrical conductivity. It has the disadvantage of low mechanical strength. In order to make up for these drawbacks, a rubbing plate in which metal powder or metal fibers are mixed to form a composite is used, but the mass is increased and the advantage of light weight is lost.

[0003]

As described above, the conventional metal-based friction plates have the drawbacks of low arc resistance and large mass. In addition, the carbon-based friction plate,
Since it has a low electrical conductivity and a low mechanical strength, a metal is compounded as an auxiliary material, and there is a drawback that the mass is as large as a metal. In order to overcome these drawbacks, the present invention was invented for the purpose of increasing the heat resistance and weight saving of the contact plate.

[0004]

In order to solve the above-mentioned problems, in the present invention, a conductive ceramic is applied to a current collecting strip. Ceramics generally have high heat resistance because of their high melting points, and have excellent wear resistance because of their high hardness, and have been used in various sliding members. In addition, ceramics have a lower density and are lighter than metal-based contact plates. However, many ceramics are insulators, and those to be applied here are borides, carbides, nitrides, silicides and the like having low specific resistance and conductivity as shown in Table 1.

One of the important conditions that the contact plate should have is that the specific resistance is small. As a value that can keep the temperature of the trolley wire below 90 ° C even if 100A of current is collected while the vehicle is stopped,
300 μΩ · cm or less is recommended, and the specific resistance of the conductive ceramics shown in Table 1 is 200 μΩ · cm or less, which is well within the allowable limit.

[Table 1]

On the other hand, ceramics is a brittle material, and whether or not the mechanical strength that the contact plate should have is satisfied is a problem. Therefore, it is necessary to use an auxiliary material that is useful for improving the toughness, and this must be a material that can withstand the high temperature required for firing ceramics. Ceramics and carbon materials that are available in fiber form are particularly effective for this purpose, but the conductivity of these auxiliary materials is not always above 300 μm.
It does not satisfy Ω · cm or less. Therefore, if these are mixed, the resistivity increases as a friction plate, and the mixing ratio of these is determined by the balance between the resistivity and the toughness. Similarly, regarding the carbon-based grounding plate, which is a brittle material, the recommended bending strength is 100 MPa or more, but the ceramics used in the present invention can sufficiently secure room temperature bending strength of 300 MPa or more.

Since ceramics have extremely high hardness,
The question is whether or not to accelerate the wear of the trolley wire.
One of the causes of wear of the trolley wire is the adhesion with the contact plate, and the other is the cutting and grinding action by the contact plate. The former is a big problem with metals that are easy to bond,
There is no problem with ceramics and carbon, which have low wettability with metals. On the other hand, with regard to the latter, in the case of ceramics, it is possible to keep the roughness of the contact surface small because it is hard and has extremely high wear resistance.If the surface finish is sufficiently smooth at the beginning, the trolley wire will not wear out. There is no promotion. Further, by using a lubricant that withstands the firing temperature of ceramics such as carbon, the smoothness can be maintained more easily.

[0008]

EXAMPLES Examples of the present invention will be described below.

Example 1 70% TiC + 30% SiC fired by hot pressing Dimensions 10 × 10 ×
Table 2 shows the results of the abrasion test of the 100 mm test piece with and without current collection.

[Table 2] The test conditions were a sliding speed of 50 km / h, a pressing force of 20 N, and a current collection current density of 80 A / cm ² . The physical properties of the test piece are as follows.

[Table 3] Density: 4.2 g / cm ³ Bending strength: 550 MPa Hardness: Hv ₁₀ 2000 Fracture toughness value: K _Ic = 5.4 MPa ・ m ^1/2 Specific resistance: 200 μΩ ・ cm

Example 2 Table 2 shows the results of a wear test performed on a test piece in which 15% by mass of graphite was mixed in TiC in order to impart lubricity to the TiC in the non-current collecting state and the current collecting state. The test conditions and test piece dimensions are the same as in Example 1. The physical properties of the test piece are as follows.

[Table 4] Density: 4.1 g / cm ³ Bending strength: 373 MPa Hardness: Hv ₁₀ 690 Fracture toughness value: K _Ic = 4.2 MPa ・ m ^1/2 Specific resistance: 100 μΩ ・ cm

For comparison, Table 2 also shows the results of the current iron-based and copper-based ground sheet materials, and it can be seen that the abrasion resistance of the examples of the present invention is superior to these.

[0012]

As described above, the current collecting contact plate according to the present invention is made of conductive ceramics or a ceramic matrix composite material (CMC) in which a reinforcing material and a lubricating material are added to the conductive ceramics. Compared with other contact plates made of iron-based or copper-based sintered alloy, it has superior wear resistance,
In addition, the lighter weight improves the dynamic followability of the trolley wire. These characteristics are particularly suitable as a current collecting sliding plate for a vehicle traveling at high speed, and are useful for reducing maintenance by extending the replacement life.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Ono 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation

Claims (1)

[Claims] 1. A sliding plate for a current collector for a vehicle, wherein a sliding portion is made of conductive ceramics composed of one or more kinds of compounds, or is made of conductive ceramics as a main material for improving toughness and lubricity. A scraping plate for current collection, characterized by comprising a ceramic matrix composite (CMC) containing the above-mentioned auxiliary materials.