JP2952288B2 - DC contact for engine starter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial application field The present invention relates to a long-life DC contact for an engine starter having excellent environmental resistance.

(2) Prior Art The structure of a DC contact for an engine starter is as shown in FIG. 1 and comprises one disk-shaped movable contact 2 and a pair of fixed contacts 1a and 1b.

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 a copper-tungsten alloy. Are known.

When the ignition key of the car is turned, the movable contact 2 is strongly pressed against the fixed contacts 1a and 1b by the action of the electromagnet formed by the retracting coil 5, and the pressure is
A is 1 mm ² per 25g (2.5Kg / 100mm ²⁾ or more, it becomes more than 100 times the contact pressure of the contact in the normal electrical circuits. In addition, an excessive current, which reaches 1200 A instantaneously when the current is cut off, flows through the battery-side contact (1a) of the fixed contacts, thereby increasing the consumption thereof.

As one of the materials for the contact for the starter, conventionally, tough pitch copper has been adopted as a material for both the fixed contact and the movable contact. The contact of this combination withstands about 50,000 uses under a normal atmosphere and a normal load current, and sufficiently satisfies the requirements for use under normal operating conditions.

Further, a combination using tough pitch copper for the movable contact and copper-tungsten for the fixed contact was later developed as a contact that can withstand long-term use. This combination of contacts can withstand 3 to 4 times the use of tough pitch copper under normal use atmosphere and load current, but high humidity, NH ₃ containing atmosphere and NO _X containing atmosphere In some cases, a tungsten compound (mainly an oxide) having a strong insulating property was generated, and a conduction failure was sometimes caused.

Japanese Patent Application Laid-Open No. 50-2165 discloses that one of Cu and Ag is used as a material for a medium-load contact that requires a large number of switching times and a long life, such as a contact for an elevator or an escalator.
One contact made of an alloy containing 15% by weight or more of C as a seed, and 0.1 to 1.5% by weight of Cr, 0.1 to 1.0% by weight of Zr, and 0.005% by weight of Si
A combination with the other contact made of a copper alloy containing any two of 1.0% by weight is described. However, this contact is completely different from the contact of the present invention in the conditions of use and therefore the alloy composition.

Furthermore, according to Japanese Patent Publication No. 56-9257, Sn 3-9% by weight, In 1-3% by weight, Cd 0.2-1
A material obtained by internally oxidizing an alloy consisting of 0.01% by weight of Ni, 0.01 to 1% by weight of Ni and the balance of Ag is known, but this is a contact for a switch for medium load AC, which is used under a low contact pressure. ,
It is not intended to be used under severe conditions of receiving a high contact pressure for direct current as in the invention of the present application. By the way, it is clear from the specification of this prior art that no evaluation test is made in the examples when the materials described therein are used as DC contacts.

It is also used as a lead material for semiconductor devices.
No. materials are known. This material contains 0.05 to 1 wt% Cr, 0.005 to 0.3 wt% Zr, 5 to 60 ppm C, and if necessary, Ni, Sn,
0.005 to 2% by weight of at least one element selected from the group consisting of Fe, Co and Be, with the balance being Cu, and excellent press punching, heat resistance and heat dissipation for the production and use of lead materials It is intended to simultaneously have various properties such as strength, conductivity and the like, but is not intended to be used as an electrical contact at all.

(3) Problems to be Solved by the Invention In view of the above-described prior art, the contact life is longer than that of a contact made of a combination of tough pitch copper and copper-tungsten, and high humidity, containing NH ₃ and NO _X gas. There has been a strong demand for the development of a contact material that operates safely even in a changing atmosphere.

(4) Means for Solving the Problems Accordingly, as described above, the inventors of the present invention have conducted intensive studies on combinations of materials that satisfy the rigorous use conditions required for a DC contact for an engine starter. The following combinations of contact materials have been developed.
That is, at least one of the fixed contacts is obtained by internally oxidizing an alloy consisting of 3 to 12% by weight of tin, 1 to 5% by weight of indium, 0.01 to 1% by weight of at least one of iron group elements, and the balance of silver and unavoidable impurities. A DC contact for an engine starter consisting of a pair of fixed contacts and a movable contact made of a copper-based material.

The movable contact is 0.05-1% by weight of chromium, and zirconium is 0.1%.
005-0.5% by weight, carbon 5-60ppm, magnesium 0.001-
The direct current contact for an engine starter according to the above (1), comprising 0.2% by weight, 0.001 to 0.2% by weight of silicon, the balance being copper and inevitable impurities.

It is.

That is, first, for the fixed contact, in the conventional tough pitch copper and copper-tungsten combined contact,
In order to further extend the service life by a factor of two, several types of materials that can be substituted for the copper-tungsten of the fixed contact were examined, and the tests were repeated, and finally, the above-mentioned silver-oxide-based material was found to be the most suitable. found. This copper - tungsten-based material, a humid atmosphere, ammonia, the NO _X gas-containing atmosphere, may cause conduction failure tungsten is selectively oxidized.

In contrast, copper-oxide-based materials are skeletal materials
Since SnO ₂ -In ₂ O ₃ is an oxide from the beginning, it is extremely stable in any use atmosphere, while silver is oxidized or sulfide or chloride layer is formed. It has been found that since the contact pressure during use is extremely high, these insulating films are easily broken, and there is no possibility of causing poor conduction. Therefore, it is most suitable as a material that can withstand opening and closing that can be several times the number of times of normal use under severe use conditions. It is for this reason that this material is the only one selected from a number of candidate materials for the fixed contact in the present invention.

Next, the reason why the Cu-Cr-Zr-based material was selected for the movable contact is as follows. First, the adoption of a harder silver-oxide material as the fixed contact of the mating material required higher welding resistance and higher resistance to deflection than tough pitch copper, but Cu-Cr- Zr-based materials satisfy this requirement well. In addition, Cu-
The Cr-Zr-based material is rich in thermal conductivity and excellent in high-temperature characteristics, and therefore has an advantage that thermal deformation can be avoided when used as a contact. In the present invention, this material is selected for the movable contact for such a reason.

In the actual combination of contact materials, only the fixed contact on the battery side, whose use condition is extremely severe compared with the motor side with respect to the arc resistance, of the pair of fixed contacts is made of a silver-oxide-based material. It has been found that a sufficiently long life can be obtained.

(5) Function The reason why the content of each component is selected within the range defined in the claims for each material of the above-mentioned fixed contact and movable contact is as follows.

(Hereinafter,% represents weight%.) About movable contact material (a) Cr Cr forms a solid solution in copper to about 0.4% and raises the softening temperature (about 200 ° C.) of copper to about 500 ° C. For this reason, Cr
It has the effect of improving rigidity (deflection resistance) and heat deformation resistance. However, 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, the conductivity is reduced. Therefore, 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 an effect of preventing welding when coming into contact with a dissimilar metal. Its content
If the content is less than 0.005%, the desired effect cannot be obtained. On the other hand, if the content is 0.5% or more, segregation occurs during dissolution and workability is extremely deteriorated. Therefore, the content is set in the range of 0.005 to 0.5%.

(C) C This component forms carbides and contributes to the refinement of crystal grains and the size of inclusions in the matrix, and has the effect of improving rigidity. However, the content is desired if the content is 5 ppm or less. Stiffness cannot be obtained. On the other hand, if it exceeds 60 ppm, the workability will be deteriorated.
6060 ppm.

(D) Mg and Si Each of these components has a deoxidizing effect and an effect of improving conductivity, but the content is 0.001%.
If less than the desired effect is not obtained, while the content is 0.2
%, The effect tends to deteriorate.
The range of the content of these elements is 0.001 to 0.2, respectively.
%.

Regarding Fixed Contacts (a) The content of Sn in molten Sn is preferably 2 to 10%, and if it is less than 2%, the current interrupting characteristics are not sufficient. Oxidation treatment becomes difficult.

(B) In The content of In at the time of melting is preferably 1 to 5%,
If it is less than 1, the effect of promoting the oxidation of Sn is small, and 1% or more is preferable in order to enhance the welding resistance and arc wear resistance for medium to heavy loads. If it exceeds 5%, the arc wear resistance is reduced, so the upper limit is made 5%.

(C) Iron group element The iron group at the time of smelting is known as an additive that finely disperses other oxides and refines the Ag matrix. In the present invention, the content of 0.01 to 1% is appropriate. is there. If the content is less than 0.01%, the effect of the addition will not be exhibited.
%, The oxide cannot be uniformly dispersed in Ag.

(6) Examples Hereinafter, the present invention will be specifically described with reference to examples.

Each material having the composition shown in Table 1 below is processed into the shape shown in the drawings to form a combined contact, and a durability test (Example 1) and an environmental test (Example 2) are performed on these contacts.
Was carried out.

Example 1 (Durability test) A contact test in which various materials listed in Table 1 were combined was subjected to a durability test under the following test conditions.

Power when energized: DC 12 volts, 100 amps Contact force: 500 g Separation force: 1000 g Switching frequency: 1200 times / hour Test environment: indoor air atmosphere Number of times of switching: 10,000 times Shape of contact test piece: See Fig. 2 As shown, both the fixed contact and the movable contact have the same rivet shape.

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

Among the conventional contacts, in a contact obtained by combining tough pitch copper and tough pitch copper, the cause of finally becoming unusable is poor conduction due to wear of the contact portion.

The tough pitch copper and copper-tungsten alloy contacts may eventually become unusable due to poor electrical conduction due to wear, but they have a variable life cycle and are subject to high-temperature, high-humidity environments and corrosive gases. Corrosion may occur in an atmosphere containing.

On the other hand, in the combined contact of the silver-oxide based alloy fixed contact and the tough pitch copper movable contact according to the present invention starting from the Ag-Sn-In based alloy, the chromium matrix added as described above is used. Of the tough pitch copper and the tough pitch copper combined contact of the conventional product, shows about four times the number of lifetimes due to the strengthening action of the alloy and the action of preventing the hard intermetallic compound generated by chromium and zirconium respectively. In the combined contact of a fixed contact of a silver-oxide-based alloy and a movable contact of a copper-chromium-zirconium-based alloy starting from an Ag-Sn-In-based alloy,
The lifetime count is further improved based on the absence of image sticking.

Example 2 (Environmental test of contacts for starter) An environmental test was performed on the contacts in which various materials listed in Table 1 were combined under the following test conditions.

Among various combinations of fixed contacts and movable contacts, Ag-Sn-In alloy (indicated by the composition before internal oxidation treatment) is used as the fixed contact, and tough pitch copper or copper-chromium-zirconium is used as the movable contact. The contact using the alloy is the contact of the present invention.

 Table 3 shows the results of the environmental test.

Each contact was exposed to a high-temperature and high-humidity atmosphere containing ammonia gas, a high-temperature and high-humidity atmosphere containing ammonia gas, and a high-temperature and high-humidity atmosphere containing nitric acid, respectively, for 150 hours, and then their contact resistance values were measured.

A contact using tough pitch copper for both the fixed contact and the movable contact has a high contact resistance value in any of the above three kinds of atmospheres, and a deteriorated layer (mainly an oxide film) is easily formed on the contact surface under high temperature and high humidity. Is shown.

Next, the contact using copper-tungsten for the fixed contact and tough pitch copper for the movable contact shows good environmental resistance even under high temperature and high humidity, and the contact resistance is maintained at a low value. It can be seen that in a humid atmosphere and a high-temperature, high-humidity atmosphere containing nitric acid, the progress of corrosion of copper-tungsten is remarkable, leading to a state of poor conduction where contact resistance cannot be measured.

On the other hand, the contact of the present invention, that is, the fixed contact of silver-oxide alloy and the tough pitch copper or copper-chromium-
A contact formed by a combination with a movable contact made of a zirconium-based alloy shows a stable low contact resistance value in all three types of atmospheres.

(7) Effects of the Invention As described in detail above, the contact of the present invention is a DC contact for an engine starter that repeatedly opens and closes, and is used in a high-temperature, high-humidity atmosphere, and at a high temperature, high temperature containing NOx gas or ammonia gas. It is sufficiently resistant to corrosion in a humid atmosphere and is optimal as a starter contact.

[Brief description of the drawings]

FIG. 1 is a view showing the structure of a DC contact for an engine starter. FIG. 2 is a view showing a shape of a contact test piece used for a durability test. 1a, 1b ... fixed contact, 2 ... movable contact, 3 ... operation switch,
4 ... Battery, 5 ... Retraction coil, 6 ... Support coil, 7 ... Motor, 8 ... Operation shaft.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuo Iwamura 1-297 Kitabukurocho, Omiya City, Saitama Mitsubishi Metals Central Research Laboratory (72) Inventor Toyozo Kusaka 2--22 Higashisakura, Naka-ku, Nagoya-shi, Aichi Prefecture No. 18, Nikko Building, 4th Floor, Mitsubishi Metal Corporation Name: Furuya Branch (56) References JP-A-50-5867 (JP, A) JP-A-58-172822 (JP, A) JP-A-58-145006 (JP, A) A) JP-A-59-123108 (JP, A) JP-A-1-55358 (JP, A) JP-A-50-2165 (JP, A) JP-A-53-106625 (JP, A) JP-A-62 -70542 (JP, A) JP-A-50-109467 (JP, A) JP-A-63-196001 (JP, A) JP-A-55-21548 (JP, U) (58) Fields investigated (Int. . ^6, DB name) H01H 1/00 - 1/04

Claims (2)

(57) [Claims] (1) at least one fixed contact is composed of 3 to 12% by weight of tin, 1 to 5% by weight of indium, and at least one of iron group elements;
A DC contact for an engine starter, comprising a pair of fixed contacts and a movable contact made of a copper-based material, which is a material obtained by internally oxidizing an alloy comprising 01 to 1% by weight, the balance being silver and unavoidable impurities. 2. A movable contact comprising 0.05 to 1% by weight of chromium, 0.005 to 0.5% by weight of zirconium, 5 to 60ppm of carbon, 0.001 to 0.2% by weight of magnesium, 0.001 to 0.2% by weight of silicon, balance of copper and inevitable impurities. 3. A DC contact for an engine starter according to claim 1.