JP2001202840A - Silver alloy contact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide silver alloy contacts which can largely reduce sulfurization although harmful cadmium is excluded and has good stability and durability. SOLUTION: Any one contact of a movable contact 10 and a static contact 11 is formed by silver alloy material being mixed with at least indium and gold, on the basis of silver as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a switch, a terminal,
Or used for movable contacts and fixed contacts such as connectors,
The present invention relates to a silver alloy contact containing silver as a main component and indium, gold or the like.

[0002]

2. Description of the Related Art A contact of this kind includes various switches for connecting and disconnecting current and signals, terminals for supplying power, and various connectors for electrically connecting video and audio signals. It is used in a wide range of applications for various devices. These various devices are often used in various environments from a high temperature to a low temperature, and there is a demand for a contact whose electrical characteristics do not change due to environmental changes.

Various types of contacts have been proposed and put into practical use, depending on the magnitude of the voltage or current to be energized, the type of signal, and the method of contacting / separating the fixed contact and the movable contact. In particular, silver alloys are often used as contacts for connecting and disconnecting relatively low voltage and low current power sources and signals. Further, in general, cadmium is blended with a silver alloy in order to improve electrical wear.

However, contact resistance of the above contacts may increase due to environmental changes, and a weak current or signal may not be transmitted. The reason why the contact resistance increases is that the surface of the contact is oxidized or sulfided to form an oxide film or a sulfide film which is an electrical insulator. In particular, in the case of a contact for transmitting a weak signal or the like, a means such as plating or cladding with a corrosion-resistant conductive metal made of gold is applied to the surface of the contact in order to prevent oxidation and sulfidation. It had been.

On the other hand, as a sliding contact, there is a commutator used for a motor. Conventionally, for this commutator, an alloy material composed of a ternary silver alloy containing 92% by weight of silver, 6% by weight of copper, and 2% by weight of cadmium is generally used. Such ternary silver alloys have been widely used for many years because of their relatively stable rectifying function, durability, and the ability to be manufactured at low cost.

However, the ternary silver alloy is relatively easily sulfided, and there is a problem that a sulfide film is formed on the surface over time to increase the contact resistance. In the case of the sliding contact, the movable contact and the fixed contact relatively slide to break the sulfide film, so that the dynamic contact resistance does not become a big problem, but the static contact resistance increases. Therefore, the commutator of the motor has a serious problem that it does not start. In addition, in a low-temperature environment, an insulator such as sludge is generated on the surface, and in the worst case, there is a problem that the motor does not start due to the insulator, and also a problem that wear occurs significantly.

On the other hand, in recent years, environmental problems have been highlighted, and it has been required to eliminate cadmium even at the contact points, particularly as cadmium is a main cause of pollution. As described above, since silver alloy used as a material of the contact contains cadmium, it is urgently necessary to deal with environmental problems in combination with characteristics problems.

[0008]

As described above, a contact made of a silver alloy is excellent in stability and durability,
There is a problem of forming a sulfide film on the surface, and therefore, rust prevention measures such as gold plating and cladding on the surface are required.
However, the gold material is expensive, and the plating and cladding processes are added, so that there is a problem that the cost is necessarily high.

It is necessary to eliminate cadmium in response to environmental problems. Cadmium has an important function of increasing arc resistance at contacts and reducing electrical wear to increase durability. It is impossible to simply exclude cadmium.

In view of the above situation, the present invention provides a silver alloy contact which can eliminate harmful substance, cadmium, greatly reduce sulfuration, and is excellent in stability and durability. Is to do.

[0011]

In order to solve the above-mentioned problems, the present invention according to claim 1 of the present invention provides a method according to the present invention, wherein one of the movable contact and the fixed contact has a main component of silver, indium and It is characterized by being formed of a silver alloy material containing at least a metal such as gold.

According to a second aspect of the present invention, in the first aspect, the contact is 0.1 to 2.5% by weight of gold as an alloy composition.
It contains 1 to 2.5% by weight of palladium, 1 to 5.0% by weight of indium, 1 to 3.0% by weight of tin, and unavoidable impurities, with the balance being silver.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a silver alloy contact according to the present invention will be described below.

FIG. 1 shows an example of a commutator for a motor to which a silver alloy according to the present invention is applied. The commutator described here has the same structure as a known commutator, and a detailed description is omitted. The commutator shown in FIG. 1 is an example of an assembled commutator.

The commutator 1 includes an insulating base 2 having a flange 2b formed at one end of a cylindrical section 2a,
Commutator pieces 3 made of conductive metal attached to
And an insulating washer 4 fitted into the outer periphery of the commutator piece 3 to press the commutator piece 3 against the outer peripheral surface of the insulating base 2 to integrally fix the two. The commutator piece 3 is formed to be curved in an arc shape, and has a commutator portion 3a and a riser portion 3b radially connected from one end of the commutator portion 3a. An end of an armature winding (not shown) is connected to the riser portion 3b.

A slit 5 having a predetermined width S is provided between the adjacent commutator pieces 3 to determine a switching timing of energization to the armature winding. Therefore, in order to make the width S of the slit 5 constant, a concave groove 2c is provided in the flange portion 2b of the insulating base 2, and the riser portion 3b of the commutator piece 3 is locked in the concave groove 2c, A spacer portion 2d is formed at the base of the portion 2b, and each commutator piece 3
Is positioned. The commutator portion 3 of such a commutator 1
A brush (not shown) is in sliding contact with a, and a current from a power supply or a control circuit is supplied to the armature winding through each commutator piece 3. As a commutator type, in addition to the above-described assembled commutator, a mold-type commutator is generally provided for practical use, but the description thereof is omitted here.

In the commutator element described above, each commutator piece 3 has a function as a movable contact, and is made of a silver alloy material containing silver as a main component and a metal material such as indium and gold. . That is, as a preferable example, silver is a main component, gold is 0.1 to 2.5% by weight, palladium 1 to 1.
2.5% by weight, indium 1 to 5.0% by weight, tin 1 to
A silver alloy material containing 3.0% by weight is used. A remarkable point in such a silver alloy material is that there is no cadmium which is generally used in the conventional commutator.

As is well known, the silver alloy material is processed into a cylindrical material or a plate material by plastic working or the like to form a material of the commutator piece 3. In the case of the assembled commutator 1 illustrated in FIG. 1, a plate-shaped commutator material is used. When the commutator 1 has a relatively large outer diameter in a completed state in the assembled commutator, as shown in FIG. 2, one side of the base material 6 made of, for example, copper is applied to the commutator material. A material on which a cladding layer 7 for cladding is formed is used. On the other hand, when the outer diameter is small, as shown in FIG.
An arc-shaped commutator piece 8 is formed using the pure commutator material.

The commutator shown in FIG. 1 using the above silver alloy material is subjected to a sulfuration resistance test and a motor mounting test, and the results after the test will be described. (1) Sulfidation resistance test As an acceleration test for testing the sulfuration of the commutator pieces, the commutator pieces 3 were immersed in a 10-fold diluted solution of ammonium sulfide.
Surface sulfidation was observed. As a result, a black sulfide film was formed on the surface of the conventional ternary silver alloy composed mainly of silver, copper and cadmium several seconds later. Further, since the sulfide film has an electrical insulating property, the contact resistance value was several kilohms or more. On the other hand, when the commutator piece 3 made of the silver alloy material according to the present invention is similarly immersed in a 10-fold diluted solution of ammonium sulfide, no change appears on its surface, and the contact resistance value after that is the same as before the test. The values were the same. That is, as a result of the test, it was found that the sulfur of the commutator piece 3 made of this silver alloy material was hardly confirmed.

(2) Motor mounting test A commutator comprising a commutator piece 3 using the above silver alloy material is provided on the rotating shaft of the rotor in the motor, and a blade is attached to the rotating shaft of the motor (not shown). , The load is 1.4
２．５2.5 g-cm. The motor was installed so that the rotation axis was horizontal. Under the following conditions, 10 test samples each of the conventional commutator made of the above-mentioned ternary silver alloy and the commutator 1 made of the silver alloy material according to the present invention were prepared. Was tested.

(Test condition 1) At normal ambient temperature, by applying a motor application voltage of 4.5 V (DC), ON and OFF are alternately repeated for 6 seconds and OFF for 2 seconds, and the motor is rotated forward and reverse in each cycle. Repeated 20,000 cycles. (Test condition 2) At a low temperature (−10 ° C.) atmosphere temperature, by applying a motor application voltage of 4.5 V (DC), ON for 7 seconds and OFF for 3 seconds are alternately repeated, and forward and reverse rotations are performed in each cycle. This was repeated for 10,000 cycles.

Test Results: Changes in Load Current and Load Speed The commutator according to the prior art and the present invention showed no significant difference in test conditions 1 and 2. That is, as compared with a silver alloy composed of silver, copper, and cadmium, which has been widely used in the past, the results that the changes in the load current and the load rotation speed were equivalent were obtained.

Test Result: Observation Result by Decomposition Under Test Condition 1, although about half of the conventional commutators were within the allowable range, commutator wear was observed. on the other hand,
In the commutator according to the present invention, such commutator wear was hardly observed. Under the test condition 2, about 60% of the conventional commutator showed commutator wear out of the allowable range, and severe brush wear was observed on the brush slidably contacting the commutator. On the other hand, one commutator according to the present invention showed slight commutator wear without any effect, but the others showed little commutator wear.

As is evident from the above test results, the commutator according to the present invention shows no formation of a sulfide film peculiar to silver by adding gold and indium. Almost no wear was observed. It is considered that silver sulfide was suppressed by gold and indium. Regarding commutator wear in a low-temperature environment, it is considered that the wear resistance and arc resistance were improved by the incorporation of indium. In the silver alloy material, in order to maintain the characteristics of silver required as a commutator, 0.1 to 2.5% by weight of gold and 0.1 to 5% of indium are required.
It is confirmed that the range of 0% by weight is appropriate, and when the range is exceeded, the properties of silver change to affect the properties.

Furthermore, 0.1 to 2.5% by weight of palladium
When blended, the hardness of the commutator increases,
It has been found that the wear resistance is further enhanced. But,
If palladium is added in an amount of 2.5% by weight or more, the hardness required as a commutator will be exceeded. Also, in the workability of the silver alloy material, there is a problem in performing the rolling and the plastic working, so that the mixing ratio is set in a balance between these.

Further, when 0.1 to 3.0% by weight of tin is blended, the welding resistance is improved. When a brush is slid on the commutator and an electric current is applied, an arc is generated when the brush passes through the slit of the commutator, and the welding phenomenon is likely to occur. Is secured, and the welding phenomenon is suppressed. Moreover, it has been found that sludge and the like are also suppressed. When the mixing ratio of tin is increased, the occurrence of the arc releases tin oxide (SnO2), which is an electrically insulating oxide, and adheres to the surface of the commutator, causing an increase in electric resistance. Usually, it can be scattered and removed from the surface of the commutator by sliding the brush, but when the mixing ratio is increased, the generation of tin oxide increases.
For this reason, the mixing ratio is set to a range that can secure the necessary welding resistance.

FIG. 2 shows a contact contact. That is, the fixed contact 10 is formed in a flat plate shape, and one end is bent to form the terminal portion 10a. On the other hand, the movable-side contact 11 joined to the fixed-side contact 10 has a substantially hemispherical tip, and is configured to be able to contact and separate from the fixed-side contact 10.

The fixed contact 10 and the movable contact 1 of the contact contacts
Both or one of them is formed of a silver alloy material containing silver as a main component and a metal material such as indium and gold. That is, preferred examples include silver as a main component, 0.1 to 2.5% by weight of gold, and 1 to 2.5% of palladium.
Wt%, indium 1-5.0 wt%, tin 1-3.0
A silver alloy material in which the weight% is blended is used. What is noteworthy in such silver alloy materials is that cadmium, which is commonly used in conventional silver alloy contacts, is not present.

Even in the above-mentioned contact contacts, the formation of a sulfide film peculiar to silver was not recognized by the addition of gold and indium, and almost no wear was recognized even in a low temperature environment. This is presumably because gold and indium suppressed silver sulfide. In particular, a connector or a charging terminal in a portable electronic device is often exposed to the outside and comes into contact with a human finger or the like in many cases. Even in such a state, discoloration or contact due to formation of a sulfide film may occur. No increase in resistance was observed. In addition, since the wear resistance and arc resistance are improved by the indium blend, even if the fixed contact 10 and the movable contact 11 are repeatedly contacted and separated several million times, no welding or wear that hinders the function is observed. Was.

In the above-mentioned silver alloy material, in order to maintain the characteristics of silver required as a contact point, gold 0.1 to 2.
The range of 5% by weight and the range of 0.1 to 5.0% by weight of indium were appropriate, and it was confirmed that when the range was exceeded, the properties of silver were changed to affect the properties.

FIG. 3 shows a modified example of the contact contact, in which the movable contact 12 to be joined to the fixed contact 10 is formed of a plate-like metal plate having a spring property, and the tip side is formed in an arc shape to form an outer surface. The fixed contact 10 is configured to be able to contact and separate therefrom. This type of contact contact can be used as a terminal such as a jack, a connector, or a plug in an electronic device.

In the modified example shown in FIG. 3, both the fixed contact 10 and the movable contact 12 or one of them has a main component of silver and a metal material such as indium and gold is compounded in the same manner as in the above-described example. It is formed of a silver alloy material, and as a preferable example, 0.1 to 2.5% by weight of gold, 1 to 2.5% by weight of palladium, and 1 to 1% by weight of silver as a main component.
A silver alloy material containing 5.0% by weight and 1 to 3.0% by weight of tin is used. Also, even in such a silver alloy material, cadmium generally used in conventional silver alloy contacts does not exist. Further, features such as the absence of a sulfide film on the surface of the contact are the same as in the above-described example, and description thereof will be omitted.

FIG. 4 shows an example in which the silver alloy material is clad on a metal base plate. As the metal base plate 13, copper having excellent conductivity and relatively low cost is selected. Then, a clad layer 14 made of the silver alloy material is formed on one surface of the metal base plate 13. The contact thus configured is used for a relatively large contact, and can be formed at a low cost because the silver alloy material is clad at a portion necessary for the fixed contact to come into contact.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and can be variously modified without departing from the gist thereof.
For example, a silver alloy containing gold and indium with silver as the main component, tin and palladium are mixed, and the electrical properties required for the contacts are changed. It is also possible to use

[0035]

As described above, according to the present invention,
Since the contacts are made of an alloy material containing silver as the main component and a metal such as indium and gold, it is possible to eliminate cadmium, which is a harmful substance, while ensuring the necessary electrical characteristics of the contacts, thereby reducing environmental problems. Can be eliminated. Further, since sulfuration is greatly suppressed, electrical characteristics, stability, and durability can be improved. For this reason, it is also possible to omit the rust prevention treatment for the contact surface which has been required conventionally, and it is possible to reduce the cost. In addition, since deterioration of characteristics in a low temperature environment can be improved, stable performance and durability can be obtained even at a low temperature.

[Brief description of the drawings]

FIG. 1 is a perspective view of a commutator according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a contact contact according to the present invention.

FIG. 3 is a sectional view showing a modification of the contact contact according to the present invention.

FIG. 4 is a sectional view showing an example in which a silver alloy material is clad on a metal base plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commutator 2 Insulating base 3 Commutator piece 3a Commutator part 3b Riser part 4 Slit 10 Fixed side contact 11 Movable side contact 13 Cladding layer

Claims (2)

[Claims] 1. A silver alloy contact, wherein one of the movable contact and the fixed contact is formed of a silver alloy material containing silver as a main component and at least a metal such as indium and gold. 2. The contact is made of a metal having an alloy composition of 0.1-2.
5% by weight, 1 to 2.5% by weight of palladium, 1 indium
2. The silver alloy contact according to claim 1, wherein the silver alloy contact contains up to 5.0% by weight, tin 1 to 3.0% by weight, and unavoidable impurities, and the balance is silver.