JPH0456020A - Dc contact for engine starter - Google Patents

Abstract

PURPOSE:To provide good anti-corrosiveness during service in a high oxidative atmosphere, cold environment, and saulty maritime environment by combining stationary cpntacts consisting of Ag-oxide series alloy with a movable contact consisting of tough pitch Cu or Cu-Cr-Zr series alloy. CONSTITUTION:At least one of a pair of stationary contacts 1a, 1b is made of a material obtained through internal oxidation of an alloy consisting of 2-10wt.% Sn, 1-5wt.% In, 0.2-6wt.% Cd, 0.01-1wt.% one of Fe group elements, and Ag as residue, plus some inevitable impurities. A movable contact 2 is, on the other hand, made of a Cu series material consisting of 0.05-1wt.% Cr, 0.005-0.5wt.% Zr, 5-60ppm C, 0.001-0.2wt.% Mg, 0.001-0.2wt.% Si, and Cu as residue, plus some inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a DC contact for an engine starter that has excellent environmental resistance and has a long life.

(2) Prior art The structure of a DC contact for an engine starter is as shown in FIG. 1, and consists of one disc-shaped movable contact 2 and a pair of fixed contacts 1a, lb.

In conventional DC contacts for engine starters, the movable contact side and the fixed contact side are both made of the same tough pitch copper, and the movable contact side is made of tough pitch copper and the fixed contact side is made of copper-tungsten alloy. Are known.

When the ignition key of the car is turned, the movable contact 2 is activated by the action of the electromagnet formed by the retraction coil 5.
is strongly pressed against the fixed contacts 1a and lb, and the pressure is 25g per 1mm (2.5Kg/l 00mm).
) or more, which is more than 100 times the contact pressure of the contacts in a normal electrical circuit. Furthermore, an excessive current of up to 120 OA instantaneously flows through the battery side contact (la) of the fixed contacts when the current is cut off, resulting in severe wear and tear.

Conventionally, fixed contacts,
Tough pitch steel has been adopted as the material for both the movable contacts. This combination of contacts can withstand approximately 50,000 uses under normal atmosphere and normal load current, and fully satisfies the requirements for use under normal operating conditions.

In addition, a combination of using tough pitch copper for the movable contact and copper-tungsten for the fixed contact was subsequently developed as a contact that can withstand even longer use. Contacts with this combination can withstand 3 to 4 times longer use under normal operating atmospheres and load currents than contacts using tough pitch copper, but are exposed to strong oxidizing atmospheres and repeated exposure to high and low temperatures. In cold environments where batteries are used, or in humid atmospheres containing salt water near the coast, oxidation or corrosion may occur, resulting in poor conductivity.

In addition, as a material for medium-load contacts that require a long life due to the large number of openings and closings, such as contacts for elevators and S-forces, Japanese Patent Application Laid-Open No. 50-2165 recommends that either Cu or Ag One contact is made of an alloy containing 15Ii% or more of C in the seeds, 01 to 1.5% by weight of Cr, 0.0% by weight of Zr.
A combination with the other contact made of a copper alloy containing any two of 1 to 1.0% by weight and 0.005 to 1.0% by weight of SiO is described. However, this contact is completely different from the contact of the present invention in terms of usage conditions and alloy composition.

Furthermore, according to Japanese Patent Publication No. 56-9257, 3 to 9% by weight of Sn and 1 to 9% by weight of In, which can withstand approximately 10,000 times of opening and closing.
3% by weight, CdO, 2~1% by weight, NiO, 01~
A material made by internally oxidizing an alloy consisting of 1% by weight and the balance being Ag is known, but this material is used as a contact for a medium load AC switch under low contact pressure, and as in the invention of the present application. It is not intended to be used under severe conditions such as direct current and high contact pressure. Incidentally, as is clear from the specification of this prior art, no evaluation test has been conducted in the Examples when the material described therein is used as a direct current contact.

Also used as a lead material for semiconductor devices.
Material No. 14 is known. This material is Cr0.05
-1% by weight, Zr O, 005-0.3% by weight, C5
~60ppm, if necessary, one or more elements selected from the group consisting of Nf, Sn, Fe, Co and Be.
oos ~ 2% by weight, the balance being Cu, and is intended for use in producing and using lead materials, which simultaneously has various properties such as excellent press punchability, heat resistance, heat dissipation, strength, and electrical conductivity. However, it is not intended to be used with electrical contacts at all.

(3) Problems to be Solved by the Invention In view of the above-mentioned prior art, it has been found that the life of contacts is longer than that of contacts made of a combination of tough pitch steel and copper-tungsten, and that they can be repeatedly exposed to strong oxidizing atmospheres and high and low temperatures. There is a strong demand for the development of contact materials that can operate safely even in humid environments containing salt water.

(4) Means to Solve the Problems Therefore, as mentioned above, the inventors of the present invention have conducted extensive research into combinations of materials that satisfy the severe usage conditions required for DC contacts for engine starters. , we have developed the following combination of contact materials. That is, ■ At least one fixed contact is made of tin 2 to 10
Weight%, Indium 1-5% by weight, Cadmium 0°2-
A pair of fixed contacts made of a material obtained by internally oxidizing an alloy consisting of 6% by weight, 0.01-1% by weight of one or more iron group elements, the balance being silver and unavoidable impurities, and a movable contact made of a copper-based material. DC contact for engine starter.

■ Movable contacts are 0.05-1% by weight of chromium, 0.5% by weight of zirconium, 5-60 pI of carbon) mm
Magnesium 0.001-0.2% by weight, silicon 0.0
01 to 0.2% by weight, the balance being steel and unavoidable impurities.

It is.

First, regarding fixed contacts, we investigated and tested several types of materials that could be used to replace the copper-tungsten in the fixed contacts in order to double the lifespan of conventional tough-pitch copper and copper-tungsten combination contacts. After repeated steps, it was finally determined that the silver-oxide material mentioned above was the most suitable. In copper-tungsten materials, tungsten selectively oxidizes in environments where copper-tungsten materials are exposed to oxidizing atmospheres, humid atmospheres containing seawater, and repeated high and low temperatures.
Otherwise, it may be oxidized and cause conduction failure.

In contrast, in silver-oxide materials, 5
n02-In, 0. Since silver is an oxide from the beginning, it is extremely stable in any usage atmosphere, whereas silver, even if it is oxidized or has a sulfide or chloride layer, is extremely stable under contact pressure during use. It was found that due to the high temperature, their insulating coatings were easily destroyed and there was no risk of conduction failure. Therefore, it is ideal as a material that can withstand opening and closing several times as many times as the normal number of uses under severe usage conditions. This is the reason why this material was selected as the only material for the fixed contact out of a large number of candidate materials in the present invention.

Next, the reason why Cu-Cr-Zr based material was selected for the movable contact is as follows. First, as a harder silver-oxide material was adopted as the fixed contact of the mating material, it became necessary to have better welding resistance and higher resistance to deflection than tough pitch copper, but Cu-C
r-Zr yarn material satisfies this requirement well. In addition, Cu-Cr-Zr materials have high thermal conductivity and excellent high-temperature properties, so when used as contacts,
This has the advantage that thermal deformation can be avoided. It is for this reason that this material was selected for the movable contact in the present invention.

In addition, in the actual combination of contact materials, of the pair of fixed contacts, only the battery side fixed contact, which has extremely harsh usage conditions compared to the motor side in terms of arc resistance, is made of silver-oxide material. It has been found that a sufficiently long life can be obtained.

(5) Regarding the materials of the fixed contact and the movable contact described above, the content of each component was selected within the range defined in the claims for the following reasons.

(Hereinafter, % represents weight %.) ■ Regarding the movable contact material (a) Cr Cr is dissolved in steel up to about 0.4%, and the softening temperature of copper (20
(around 0°C) to approximately 500°C. For this reason,
Cr has the effect of improving rigidity (flexibility resistance) and heat deformation resistance, but if the content is less than 0.05%, the desired effect cannot be obtained; on the other hand, if the content is 1% or more, Since this results in a decrease in conductivity, the content was determined to be 0.05 to 1%.

(b) Zr Zr precipitates at the grain boundaries of an alloy of copper and Cr, and has the effect of preventing welding when it comes into contact with dissimilar metals. If the content is less than o, oos%, the desired effect cannot be obtained; on the other hand,
If it exceeds 0.5%, segregation will occur during melting and the workability will be extremely deteriorated, so the content should be reduced to 0.5%.
It is set within the range of .

The component (c) forms carbides, contributes to the refinement of crystal grains and the size of inclusions in the matrix, and has the effect of improving rigidity, but when the content is 5 ppm If the content is less than 60 ppm, the desired stiffness cannot be obtained, and if it exceeds 60 ppm, the workability deteriorates, so the range of the content was determined to be 5 to 60 ppm.

(d) Mg and Si These components both have a deoxidizing effect and an effect of improving conductivity, but their content is 0.001
If the content is less than 0%, the desired effect cannot be obtained;
．． If it exceeds 2%, the above effects tend to deteriorate, so the range of the content of these elements is set to 0.0%.
It was set at 01 to 0.2%.

■ Regarding fixed contacts (a) Sn The content of Sn during melting is preferably 2 to 10%. If it is less than 2%, the current interrupting characteristics will not be sufficient, and if it exceeds 10%, the contact resistance will be excessive and during manufacturing. Oxidation treatment becomes difficult.

(b) In The appropriate In content during melting is 1 to 5%, and 1%
If it is less than 1%, the effect of promoting Sn oxidation will be small, and in order to enhance welding resistance and arc wear resistance for medium to heavy loads, it is preferably 1% or more. Moreover, if it exceeds 5%, the arc wear resistance deteriorates, so the upper limit was set at 5%.

(c) Cd Addition of Cd improves the castability of the ingot alloy. The content of Cd during melting is preferably 0.2 to 6%, and 0.2%.
If the Cd content is less than 6%, it is insufficient to maintain castability comparable to Ag-Cd base metal, and if the Cd content exceeds 6%,
Since arc wear resistance deteriorates, the upper limit was set to less than 6%.

(d) When iron group elements are melted, other oxides are finely dispersed.
It is known as an additive that refines the g matrix, and in the present invention, it is appropriate to contain it in an amount of 0.01 to 1%. This is because if the content is less than 0.01%, the effect of addition will not appear, while if it exceeds 1%, the oxide will not be uniformly dispersed in Ag.

(6) Examples The present invention will be specifically explained below using examples.

Each material having the composition shown in Table 1 below was processed into the shape shown in the drawing to make a combination contact, and these contacts were subjected to a durability test (Example 1) and an environmental test (Example 2). .

Example 1 (Durability Test) A durability test was conducted on contacts made of various combinations of materials listed in Table 1 under the following test conditions.

Electric crab DC 24 ports when energized, 50 ampere Contact crab 500 g Opening force + 1000 g Opening/closing frequency: 1200 times/hour Environmental atmosphere test in two rooms Opening/closing frequency: 10,000 times Contact test piece shape: Figure 2 As shown in , both the fixed contact and the movable contact have the same rivet shape.

Table 2 shows the total amount of wear and contact resistance of the movable contact and fixed contact test pieces after opening and closing 10,000 times using a large relay.

Among conventional contacts, contacts made of a combination of tough-pitch copper and tough-pitch copper eventually become unusable due to poor conduction due to wear and tear of the contact portion.

In addition, contacts made of a combination of tough pitch steel and copper-tungsten alloy eventually become unusable due to poor conductivity due to wear and tear; Corrosion may occur in atmospheres containing

On the other hand, in the combined contact of the silver-oxide based alloy fixed contact and the tough pitch copper movable contact made of the Ag-5nIn based alloy as a starting material in the present invention, the chromium matrix is strengthened as described above. Due to the adhesion prevention effect of the hard intermetallic compounds produced by chromium and zirconium, the service life is approximately four times longer than that of the conventional contact made of tough pitch copper and tough pitch copper. A combination of a fixed contact made of a silver-oxide alloy and a movable contact made of a copper-chromium-zirconium alloy made from a 5n-1% alloy as a starting material has a lifespan of more than improves.

Example 2 (Environmental test of starter contacts) Environmental resistance tests were conducted on contacts made of various combinations of materials listed in Table 1 under the following test conditions.

Among various combinations of fixed contacts and movable contacts, Ag-5n-In alloy (shown as composition before internal oxidation treatment) is used as the fixed contact, and tough pitch copper or copper-chromium-zirconium alloy is used as the movable contact. The contact of the present invention uses an alloy.

The results of the environmental test are shown in Table 3.

Table 3 y1 environment test (left for 500 hours in various atmospheres) Each contact was tested in ■ ozone atmosphere, ■ high temperature (12
0°C) and low temperature (-30°C), and exposed to an atmosphere of sprayed salt water for 500 hours, their contact resistance values were measured.

Contacts using tough pitch copper for both fixed and movable contacts are
The contact resistance value is high in any of the above three atmospheres, indicating that a deteriorated layer (mainly an oxide film) is likely to be formed on the contact surface.

Second, contacts using copper-tungsten for the fixed contacts and tough pitch copper for the movable contacts exhibit good environmental resistance in environments subjected to thermal cycles and sprayed salt water, and have low contact resistance. However, it can be seen that corrosion of copper-tungsten is somewhat large in an atmosphere containing ozone.

On the other hand, the contact of the present invention, which is a combination of a fixed contact made of silver-oxide alloy and a movable contact made of tough pitch copper or copper-chromium-zirconium alloy, can be used in all three types of atmospheres. It shows a stable and low contact resistance value.

(7) Effects of the Invention As detailed above, the contact of the present invention can be used as a DC contact for an engine starter that frequently opens and closes, in a highly oxidizing atmosphere, and in environments in cold regions.
Furthermore, it exhibits sufficient corrosion resistance in environments with strong salt damage near the coast, making it ideal as a contact point for stators.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a DC contact for an engine starter. FIG. 2 is a diagram showing the shape of a contact test piece used in the durability test. In, lb,, fixed contact, 211. Movable contact, 3
039 activation switch, 408. battery 590
．． retraction coil, 680. Support coil, 700.
Motor, L11 operating axis. Figure 1

Claims (2)

[Claims] (1) At least one fixed contact contains 2 to 10% by weight of tin
, a material obtained by internally oxidizing an alloy consisting of 1 to 5% by weight of indium, 0.2 to 6% by weight of cadmium, 0.01 to 1% by weight of one or more iron group elements, and the balance being silver and unavoidable impurities. A DC contact for engine starters consisting of a pair of fixed contacts and a movable contact made of copper-based material. (2) The movable contact contains 0.05 to 1% by weight of chromium, 0.005 to 0.5% by weight of zirconium, and 5 to 60 ppm of carbon.
Magnesium 0.001-0.2% by weight, silicon 0.0
The direct current contact for an engine starter according to claim 1, comprising 0.01 to 0.2% by weight, the balance being copper and unavoidable impurities.