JP2007093472A - Electric contact material and sliding liquid level detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric contact material having high reliability over a long period of time even by performing not only use under a normal environment but also use under sulfur component existence such as gasoline, and to provide a sliding liquid level detector even by possessing one contact without increasing an assembling cost. <P>SOLUTION: An electric contact material contains 13 wt.% or more of chromium, consists of iron-chromium alloy containing 30 wt.% or less, and contains 0.5-3 wt.% or less of molybdenum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrical contact material, particularly an electrical contact material suitable for a sliding contact. The present invention also relates to a sliding liquid level detector using such an electrical contact material.

  As a sliding-type liquid level detector (liquid level gauge) such as an automobile gasoline tank, a float that operates following the fluctuation of the liquid level, and increases or decreases in conjunction with the movement of the float. A sliding liquid level detector provided with a variable resistor that outputs an electric resistance value has been used.

  As a variable resistor, it has a sliding contact that interlocks with the movement of the float and a fixed contact that has an electric resistor, and depends on the electrical resistance value that is output according to the position of the sliding contact that slides on the fixed contact. A liquid level detector for detecting the liquid level position in the tank is used.

  Here, a variable resistor used in a liquid level detector according to a conventional technique (Japanese Patent Laid-Open No. 11-337387 (Patent Document 1)) will be described with reference to FIG.

  FIG. 3 shows the configuration of the variable resistor of the sliding type liquid level detector disclosed in the above-mentioned publication. FIGS. 3 (A) and 3 (B) are a front view and a cross section of the main part, respectively. FIG. In these drawings, the sliding type liquid level detector is formed by forming a radial array of a plurality of conductor patterns 104 on the insulating substrate 106 made of ceramic at an appropriate interval, for example, by printing, A part of the array consisting of 104 is covered with the electric resistors 105 by, for example, printing over a plurality of rows.

  Two sliding contacts 111 and 112 which are sliding contacts sliding on a fixed contact formed on the conductor pattern 104 serve as sliding contacts, and the contact plate 108 fixed by the caulking means floats according to the position of the liquid level. In contact with any one of the conductors of the plurality of rows of conductor patterns 104 according to the position of the liquid surface, and in contact with one end of the electric resistor 105. The electric resistance value formed between the contact plate 108 provided with the sliding contact is a value corresponding to the liquid level.

  Here, the contacts may be worn due to sliding, and a failure such as an incorrect value may occur due to loss of contact or the like.

  Furthermore, these contact portions may become poor in contact due to sulfuration or deterioration due to sulfur contained in gasoline or the like, and failure such as measurement being impossible or incorrect values may occur.

  Regarding the latter problem, in the technique described in this prior art publication, the two sliding contacts 111 and 112 include a silver palladium (AgPd) alloy, a silver nickel (AgNi) alloy, a silver tin (AgSn) alloy, nickel (Ni ), A contact material combining any one of nickel chrome (NiCr) alloys is proposed. The sliding contacts 111 and 112 made of these materials are fixed by caulking means and used in any combination. Durability and contact reliability are improved by complementing the characteristics of each material by contact with two contact points of different materials.

  However, in the above-mentioned prior art, there are problems that the contact material cost increases due to the two contact points, and that the assembly cost such as caulking increases, and the former problem is that the contacts wear due to sliding. The failure caused by the disappearance of the contacts, etc., could not be prevented.

Further, as disclosed in JP-A-2002-202179 (Patent Document 2), when Au—Co is used as an alloy that achieves both sulfidation resistance and wear resistance for the sliding contact, expensive gold is used. This increases the cost and uses a gold alloy having a low hardness, which causes a problem of severe wear and short life.
JP 11-337387 A JP 2002-202179 A

  The present invention improves the above-described conventional problems, that is, it can be used in a normal environment, as well as in the presence of a sulfur component such as gasoline, and has a highly reliable electrical contact over a long period of time. It is an object of the present invention to provide a sliding liquid level detector having a long life and high reliability even with one contact point without increasing the material and the assembly cost.

  In order to solve the above problems, the electrical contact material of the present invention comprises an iron-chromium alloy containing 13 wt% or more and 30 wt% or less of chromium and molybdenum as described in claim 1, and Further, it is characterized by containing molybdenum in an amount of 0.5 wt% to 3 wt%.

As described in claim 2, the electrical contact material of the present invention is the electrical contact material according to claim 1, characterized in that the iron-chromium alloy contains 16% by weight or more of chromium.
Furthermore, as described in claim 3, the electrical contact material of the present invention is the electrical contact material according to claim 2, wherein the iron-chromium alloy contains 25% by weight or more of chromium.

  Further, in order to solve the above-mentioned problem, the sliding type liquid level detector of the present invention is linked to a float that operates following the fluctuation of the liquid level, and to the movement of the float. A liquid surface having a sliding contact and a fixed contact having an electric resistor, and detecting a liquid surface position in the tank by an electric resistance value generated by the sliding contact sliding on the fixed contact and the electric resistor It is a detector, Comprising: At least one of the said stationary contact and a sliding contact consists of the electrical contact material in any one of Claim 1 thru | or 3.

The electrical contact material according to the present invention according to claim 1 has high wear resistance and is extremely corrosive not only in use in a normal environment but also in the presence of a sulfur component such as gasoline. In addition to being a highly reliable electrical contact material, it is a highly reliable electrical contact material, and molybdenum disulfide (MoS ₂ ) generated by the chemical reaction between the sulfur component and molybdenum is applied to the sliding contact in the presence of the sulfur component. Since it functions as a barrier for the reaction between high chromium steel, which is a metal material, and sulfur, sulfidation resistance is further improved.

  Furthermore, since the generated molybdenum disulfide functions as a lubricant, the operation is smooth in sliding as a sliding contact, and the effect that the wear of the contact is prevented is also obtained.

  The liquid level detector according to the present invention according to claim 4 is reliable because the contact is not easily corroded not only in use in a normal environment but also in the presence of a sulfur component such as gasoline. In addition, when used in the presence of sulfur, molybdenum disulfide generated by a chemical reaction between the sulfur component and the molybdenum component functions as a lubricant. Smooth and good follow-up to fluctuations in the liquid level enables more accurate measurement, prevents contact wear, and increases the service life.

  The electrical contact material of the present invention comprises an iron-chromium alloy containing 13 wt% or more and 30 wt% or less of chromium and molybdenum, and contains 0.5 wt% or more and 3 wt% or less of molybdenum.

  In the above iron-chromium alloy, if the chromium content is less than 13% by weight, sufficient corrosion resistance against sulfuration or the like cannot be obtained. When the chromium content is 16% by weight or more, higher corrosion resistance can be obtained, but in order to obtain higher corrosion resistance, it is preferable to contain chromium by 25% by weight or more. In addition, it is preferable that the chromium content is 30% by weight or less in order to secure processability and assembling property and to suppress material costs.

  In the electrical contact material of the present invention, it is necessary that the addition amount of molybdenum be 0.5 wt% or more and 3 wt% or less of the whole. If the amount of molybdenum added is less than 0.5% by weight, a sufficiently high corrosion resistance cannot be obtained, and if it exceeds 3% by weight, workability and assemblability are remarkably deteriorated.

  As such an alloy, SUS434, SUS447JI, SUSXM27, etc. are known in the JIS standard and can be used. Further, each metal of iron, chromium and molybdenum, or an alloy and molybdenum made of iron and chromium are put in a graphite crucible and melted in a vacuum or an inert gas atmosphere (1600 to 1700 ° C.) in a high frequency melting furnace or the like. It can also be produced by stirring for 5 to 20 minutes and casting using a graphite or ceramic mold.

  In principle, the electrical contact material according to the present invention is composed of iron, chromium, and molybdenum, but may contain trace amounts of other components as long as the effects of the present invention are not impaired.

  The electrical contact material according to the present invention obtained as described above can be made into a desired contact shape through a material shape such as a plate shape or a rod shape, or a molten alloy is used as a mold. The desired contact shape can be obtained directly by casting or the like.

  Here, an example of a sliding liquid level detector using the electrical contact material according to the present invention will be described with reference to the drawings.

  1 and 2 are a front view and a partially enlarged sectional view showing a sliding liquid level detector 1 according to the present invention, respectively. The sliding-type liquid level detector 1 includes a float that operates following changes in the liquid level, a sliding contact that moves in conjunction with the movement of the float, and a fixed contact that has an electrical resistor. A liquid level detector that detects a liquid level position in the tank based on an electric resistance value generated by a sliding contact that slides on the fixed contact and an electric resistor, and a plurality of fixed contacts are connected in the longitudinal direction. Then, at least one of the fixed contact and the sliding contact is made of the electrical contact material according to the present invention. The sliding type liquid level detector 1 includes a resin frame 2, a metal float arm 3, a resin holder 4, a contact plate 5, a float 6, and a resistor 7.

  One end portion of the float arm 3, that is, the sliding shaft portion 3a is inserted into a mounting hole 4a1 provided in the mounting portion 4a of the holder 4, and an intermediate portion 3b of the float arm 3 extends from the mounting portion 4a. In addition to being clamped and fixed by the claw portion 4b formed in this manner, the claw portion 4b is rotatably inserted into an attachment hole 2a1 provided in the attachment portion 2a of the frame 2. A float 6 is attached to the other end of the float arm 3, that is, the tip 3c.

  The holder 4 is connected to the frame 2 by the sliding shaft portion 3 a of the float arm 3 and biased by a coil spring 8 attached to the attachment portion 2 a of the frame 2, so that the attachment portion 2 a of the frame 2 and the holder 4 are attached. Although the portion 4a does not contact, the U-shaped cross-sectional portion 4c that is further bent and extended from the claw portion 4b of the holder 4 contacts over the swing stroke of the float arm 3 so as to sandwich the arc-shaped end portion 2b of the frame 2 Thus, it is attached to the frame 2 so as to rotate together with the float arm 3. The contact plate 5 has elasticity, is fixed to the holder 4, and a sliding contact 5 a is fixed to the tip of the contact plate 5 by caulking means or the like. The sliding contact 5 a is urged by the elasticity of the contact plate 5, and is at the rotational position of the float arm 3 among the plurality of fixed contacts 7 a each connected to the resistor 7 attached to the frame 2. It is in contact with the corresponding contact.

  The sliding type liquid level detector 1 is mounted in a tank (not shown) for storing liquid, and when the float 6 moves up and down due to fluctuations in the liquid level, the float arm 3 moves around the mounting hole 2a1. It rotates within an angle range (that is, a range between the lowest point and the highest point (F point) of the liquid level). By this rotation, the end face of the sliding contact 5a of the contact plate 5 slides on the plurality of fixed contacts 7a connected to the resistor 7 corresponding to the position of the float 6, and at this time, what is the sliding contact 5a? Since it is in electrical contact with any one of the plurality of fixed contacts 7a and a change in resistance value between one end of the resistor 7 and the sliding contact 5a is detected by a sensor circuit (not shown), A detection signal indicating the fluctuation amount can be extracted. In this example, the plurality of sliding contacts 5a are made of the electrical contact material according to the present invention.

  The electrical contact material is made of seven types of chromium-iron alloys containing 5%, 10%, 13%, 16%, 20%, 25%, or 30% by weight of chromium. Then, an alloy blended so that the molybdenum content of the obtained material is 0.3, 0.5, 1, 2, 3, or 5% by weight is obtained, and the materials shown in Tables 1 to 3 as alloy compositions are obtained. It was.

  In Tables 1 to 3, the number with “%” immediately before “Cr” in the alloy composition column indicates the chromium content in the raw chromium-iron alloy by weight%, and immediately before “Mo”. Molybdenum content in the material from which numbers with “%” are obtained is expressed in weight%.

  For comparison, in addition to these materials made of iron, chromium and molybdenum, an electrical contact material made of a gold alloy (according to Japanese Patent Laid-Open No. 2002-202179) made of 1 wt% cobalt and 99 wt% gold (Table 3). "Au-1% Co") and a silver alloy composed of 70% by weight of silver and 30% by weight of palladium (general materials for sliding contacts used in corrosive environments) (" Ag-30% Pd ").

  These materials are processed by cutting or sticking to form a cylindrical contact material having a diameter of about 2 mm and a height of about 4 mm, and fixed as a sliding contact 5 a of the sliding liquid level detector shown in FIGS. 1 and 2 by caulking. did. If the workability was low and could not be processed, or if the workability was sufficient but could not be assembled to the sliding liquid level detector by caulking, the "workability and assembly" It was evaluated as “defective” and no subsequent durability test was conducted. As the fixed contact 7a, a gold alloy composed of 70% by weight of gold and 30% by weight of palladium was used.

  The endurance test is a 1,000,000 sliding test that assumes long-term use in gasoline (with a sulfur content of 100 ppm) and falls between the lowest and highest points (F point) of the liquid level. Went by.

  Here, if the wear amount of the sliding contact is 60 μm or less and the wear amount of the fixed contact is 4 μm or less, it is evaluated that it has sufficient durability as a contact in the sliding liquid level detector, and increases. When the contact resistance is 100Ω or less, it is evaluated that there is sufficient electrical connection stability as a contact point in the sliding liquid level detector.

  Moreover, if there is no discoloration in the visual observation of the sliding surface, it is evaluated that there is sufficient corrosion resistance as a contact point in the sliding liquid level detector.

  Further, the contact material cost was evaluated as “inexpensive” when no noble metal was used as a raw material, and “expensive” when noble metal was used as a raw material. These evaluation results are shown in Tables 1 to 3.

  According to Tables 1 and 2, the sliding contact using the electrical contact material according to the present invention is formed with less wear and wear as a sliding contact while having sufficient workability and assembly. Due to the excellent lubricity effect of molybdenum sulfide, the wear amount of the fixed contact on the other side can be kept low, the increase in contact resistance is small, and the degree of corrosion is little, or there is little discoloration of the appearance. It can be understood that it will be inexpensive. Here, the fixed contact is generally formed by printing or the like and is very thin, and it is extremely important to suppress the wear amount of the fixed contact in order to improve the life and reliability of the contact.

  In the above, evaluation was made as a contact with a sliding liquid level detector. However, the electrical contact material of the present invention is not only an urban environment rich in sulfur oxide (SOX), but also an industrial zone, a hot spring or a volcanic zone. It can be suitably used as an electrical contact material for electrical contacts used in motors, switches, relays, and the like in a sulfurized atmosphere.

  The electrical contact material of the present invention is excellent in wear resistance and corrosion resistance and is lubricated when used in an environment where a sulfur component is present, such as a sliding liquid level detector for detecting the liquid level of a fuel containing a sulfur component. Since this improves the wear, it is possible to prevent wear of the counterpart metal to be slid, so that it can be used particularly suitably not only as a general electric contact but also in an environment containing a sulfur component.

It is a figure (front view) which shows the example of the sliding-type liquid level detector using the electrical contact material which concerns on this invention. It is a figure (partial expanded sectional view) which shows the example of the sliding-type liquid level detector using the electrical contact material which concerns on this invention. It is a figure (partial enlarged view) which shows the example of the sliding type liquid level detector using the electrical contact material which concerns on a prior art. (A) Partial enlarged view (front), (B) Partial enlarged view (side).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sliding liquid level detector according to the present invention 2 Frame 3 Float arm 4 Holder 5 Contact plate 5a Sliding contact 6 Float 7 Resistor 7a Fixed contact

Claims (4)

  An electrical contact material comprising an iron-chromium alloy containing 13 wt% or more and 30 wt% or less of chromium and molybdenum, and containing 0.5 wt% or more and 3 wt% or less of molybdenum.   The electrical contact material according to claim 1, wherein the iron-chromium alloy contains chromium in an amount of 16% by weight or more.   The electrical contact material according to claim 2, wherein the iron-chromium alloy contains chromium in an amount of 25% by weight or more. A float that operates following the fluctuation of the liquid level, a sliding contact that interlocks with the movement of the float, and a fixed contact that has an electric resistor, a sliding contact that slides on the fixed contact, and an electric resistance A liquid level detector for detecting a liquid level position in the tank based on an electrical resistance value generated by the body,
A sliding liquid level detector, wherein at least one of the fixed contact and the sliding contact is made of the electrical contact material according to any one of claims 1 to 3.

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